Meniscus Function

The menisci provide several vital mechanical functions in the knee joint. They act as a spacer between the femoral condyle and the tibial plateau and, when there are no compressive weight-bearing loads across the joint, limit contact between the articular surfaces. The amount of joint narrowing due strictly to the physical absence of the menisci is in the range of 1 to 2 mm.

Critical Points CLINICAL BIOMECHANICS

Functions of the Menisci

• Spacer, prevents contact between articular surfaces.

• Load-bearing:

50% compressive load of knee joint transmitted through menisci at 0° extension.

85% compressive load of knee joint transmitted through menisci at 90° flexion.

• Increase contact area, reduce contact stress

Partial meniscectomy (15%–34%) increases contact pressures by >350%.

• Contributes to joint stability.

• Shock absorption during walking.

• May assist in overall lubrication of articular surfaces.

Suture Repair Biomechanics

• Studies comparing biomechanical properties of vertical and horizontal sutures, and sutures to meniscus repair devices

Vertical sutures superior initial fixation strength and stiffness during load-to-failure testing compared with horizontal sutures and repair devices.

Vertical sutures lower displacements under cyclical loading conditions compared with horizontal sutures and repair devices.

Under static-loading conditions, the menisci assume a significant load-bearing function in the tibiofemoral articulation.^2,26,45 At least 50% of the compressive load of the knee joint is transmitted through the menisci in 0° of extension, and approximately 85% of the load is transmitted at 90° of flexion.² The presence of the menisci increases the contact area to 2.5 times the size of a meniscectomized joint. The larger contact area provided by the menisci reduces the average contact stress (force/unit area) acting between the joint surfaces. Removal of as little as 15% to 34% of a meniscus increases contact pressures by more than 350%.¹²⁴

Lee and colleagues⁷⁵ evaluated the biomechanical effects of serial meniscectomies in the posterior segment of the medial meniscus. Compared with the intact state, the medial contact area decreased from 20% (after removal of 50% of the posterior segment of the medial meniscus) to 54% (total meniscectomy). Medial contact stress increased from 24% (50% meniscectomy) to 134% (total meniscectomy). Medial peak contact stress increased from 43% (50% meniscectomy) to 136% (total meniscectomy). The peripheral portion of the medial meniscus provides a greater contribution to increasing contact area and decreasing contact stresses than the central portion. Peak contact stresses increase proportionally with the amount of meniscus removed.

Medial meniscectomy performed after sectioning of the ACL results in increased anterior translation at 20° of knee flexion compared with that measured in knees with an intact ACL.⁷⁷ Thus, the loss of the medial meniscus after an ACL rupture is problematic, especially in varus-angulated knees. In knees with posterior cruciate ligament (PCL) ruptures, the increase in posterior tibial translation allows a change in tibiofemoral contact in which the menisci posterior horns have a reduced weight-bearing function. This is sometimes referred to as a “PCL meniscectomy.” The effect is greater for the medial compartment in which the middle and anterior thirds of the medial meniscus have less weight-bearing function than the lateral meniscus.

The menisci remain in constant congruity to the tibial and femoral articular surfaces throughout knee flexion and extension^135,146 and are thus believed to contribute to stability to the knee joint.⁹² The lateral meniscus provides concavity to the lateral tibiofemoral joint owing to the normal posterior convexity of the lateral tibial condyle, allowing the stabilizing effect of joint weight-bearing forces to reduce lateral compartment anterior and posterior translations.⁸² Total lateral meniscectomy results in a 45% to 50% decrease in total contact area and a 235% to 335% increase in peak local contact pressure.¹⁰³

Loss of the medial meniscus results in a smaller, more medial displacement of the center of pressure. Load is subsequently transmitted through the articular cartilage and subchondral bone to the underlying cancellous bone through this more central route, thus stress-shielding the proximal aspects of the medial tibial cortex. The deleterious effects of meniscectomy on tibiofemoral compartment articular cartilage have been demonstrated in multiple experimental studies.^{65,104,132,145} For these reasons, it is paramount to preserve meniscal function, if possible, in knees with varus osseous malalignment.

In addition, the menisci provide shock absorption to the knee joint during walking and are theorized to assist in overall lubrication of the articular surfaces.^92,141

Meniscus Suture Repair Biomechanics

Various suture repair techniques and suture materials have been tested experimentally to determine initial fixation strength and performance under cyclical loading.^13,106 Suture techniques have also been compared with several meniscus repair devices.* Post and coworkers¹⁰⁶ compared the pull-out strength of vertical mattress, horizontal, and knot-end sutures in a porcine model using either 2-0 Ethibond, 0-polydioxanone sutures (PDS), or 1-PDS suture material. The vertical mattress technique with 1-PDS suture had significantly greater (P < .05) mean load-to-failure values than any other combination (146 ± 17 N). This was followed by the vertical mattress technique with 0-PDS suture material (116 ± 28 N). The vertical mattress technique had significantly greater mean load-to-failure values than the horizontal mattress technique, regardless of suture type (P < .0001). There was no difference in the relative strength between horizontal and knot-end suture techniques.

Asik and coworkers¹³ compared the failure strengths of vertical, vertical mattress, vertical loop, horizontal mattress, and knot-end suture techniques in a bovine model. Each group consisted of four medial menisci, and 1-Prolene suture material was used in all specimens. The vertically oriented sutures showed significantly higher initial fixation strengths (mean, ∼131 N) compared with the knot-end (64 N; P < .001) and horizontal (98 N; P < .001) techniques. In another study, Asik and Sener¹² compared the mean load to failure of a variety of meniscus repair devices with that of horizontal and vertically oriented sutures in a bovine model. The strongest repair method was the vertical sutures with 0 PDS (mean, 104.7 N). The mean failure strengths of all of the devices were lower than both suturing techniques (range, 9.8 N for the Arthrex dart to 51.4 N for the T-Fix device).

Miller and associates⁸⁸ assessed healing rates and chondral injuries of three all-inside devices in a goat model 6 months after implantation. A 15-mm longitudinal tear was created in the peripheral 25% of the posterior-central horn and then repaired with either two Meniscal Fasteners (Mitek, Ethicon, Westwood, MA), two 10-mm BioStingers (Linvatec, Largo, FL), or two 10-mm Clearfix Meniscal Screws (Mitek). A group of goats that had undergone repair with two vertical mattress sutures for a similar lesion was used for control.⁸⁹ The authors reported that the suture group had a significantly higher rate of healing (93% completely healed, 7% no healing) than all three of the device groups (P < .01), which ranged from 43% to 54% complete healing and from 0% to 25% no healing. In addition, significant chondral injury was observed in the majority of animals in all three device groups.

Several investigations compared the biomechanical properties of meniscus arrows with those of vertical and horizontal sutures.^{4,12,16,24,37,110,126,143} Vertical sutures are superior to both horizontal sutures and meniscus arrows in mean load-to-failure values.^12,42,143 Dervin and colleagues³⁷ reported that the meniscus arrow had approximately one half the failure strength of vertical sutures (30 N and 58 N, respectively; P < .001). Song and Lee¹²⁶ found that the maximum tensile strength of the meniscus arrows was significantly lower (38 N) than both vertical (114 N) and horizontal (75 N) sutures (P < .05). Walsh and coworkers¹⁴³ reported that the meniscus arrow and meniscus staple had significantly lower mean force-at-failure values (44.3 N and 17.8 N, respectively) than vertical suture (73.9 N; P < .005).

Rankin and associates¹¹⁰ used a bovine model to compare vertical sutures, horizontal sutures, meniscus arrows, and T-Fix repairs in which three sutures or devices were used for each repair. Vertical sutures were stronger than all other repair methods and showed the smallest average residual displacement (0.21 mm). The force required to generate 2 mm of tear displacement was greatest for the vertical sutures and least for the arrow (143 N and 43.6 N, respectively; P < .0001). The superior strength of vertical sutures is believed to be due to the perpendicular orientation to the circumferential collagen bundles of the meniscus.¹¹⁰

Becker and colleagues²¹ compared the biomechanical behavior of several biodegradable implants for meniscus repair with that of vertical and horizontal mattress sutures in response to cyclical loading and load-to-failure testing. Seventy lateral menisci were removed from patients aged 52 to 60 years prior to total knee replacement. One suture or device was used for each repair. The pull-out strength of the vertical and horizontal sutures was superior to those of the implants. Superior stiffness during load-to-failure testing and lower displacement under cyclical loading were found for the vertical sutures compared with horizontal sutures and all implants.

Nyland and associates¹⁰⁰ evaluated displacement (repair site gapping) of all-inside vertically or horizontally placed FasT-Fix (Smith & Nephew, Endoscopy Division, Andover, MA) devices to horizontally placed RapidLoc devices (Mitek Surgical Products, Westwood, MA) under cyclical loading conditions in human cadavers (mean age, 65 ± 7.7 yr). Two implants placed 5 mm apart were used for each repair. The vertical FasT-Fix group had significantly less displacement after 500 cycles than the other two groups (P < .01) and greater stiffness.

Meniscus Repair Healing

There are few published experimental studies on the strength of a healing meniscus suture repair (without cell-based therapy or growth factors) subjected to tensile loads. Newman and associates⁹⁴ measured the mechanical behavior of canine joints after repair of peripheral and radial meniscus tears. Contralateral limbs served as controls. The peripheral tears were repaired with four vertically oriented sutures, and the radial tears were repaired with two horizontally oriented sutures. Thirteen weeks later, the peripheral repairs demonstrated no statistically significant differences between the repaired and the control limb in compressive force-displacement behavior, input energy, and ratio of dissipated to input energy. All of the peripheral repairs healed, with no gapping at the repair site. However, the radial repairs showed significant differences in the structural and material properties compared with the control limb. These repairs healed with 3- to 5-mm-wide fibrovascular scars, and 10 of 17 (59%) specimens failed to refill the gap completely to the inner meniscal rim. The authors concluded that the mechanical function was restored after peripheral repairs, but not after radial repairs in this animal model.

In a rabbit model, Roeddecker and colleagues¹¹⁷ studied tissue strength after repair of longitudinal meniscal lesions located in the central third region. A 3-mm lesion was created and then either left alone, repaired using one suture, or repaired with a fibrin sealant. The contralateral limb was used as a control. After 6 weeks, the mean relative strength of the healing tissues were 26% (suture) and 42.5% (fibrin glue) of the control values. These strength values remained similar after 13 weeks.

Patient Preparation

The patient is instructed to use a soap scrub of the operative limb (“toes to groin”) the evening before and morning of surgery. Lower extremity hair is removed by clippers, and not a shaver. Antibiotic infusion is begun one hour prior to surgery. A nonsteroidal anti-inflammatory drug (NSAID) is given to the patient with a sip of water upon arising the morning of surgery (which is continued until the 5th postoperative day unless there are specific contraindications to the medicine). The use of an NSAID and a postoperative firm double-cotton, double-Ace compression dressing for 72 hours (cotton, Ace, cotton, Ace layered dressing) has proved very effective in diminishing soft tissue swelling and is used in all knee surgery cases. A urinary indwelling catheter is not used unless there are specific indications. The patient’s urinary output and total fluids are carefully monitored during the procedure and in the recovery room. The knee skin area is initialized by both the patient and the surgeon before entering the operating room, with a nurse observing the procedure. The identification process is repeated with all operative personnel with a “time-out” before surgery to verify the knee undergoing surgery, procedure, allergies, antibiotic infusion, and special precautions that apply. All personnel provide verbal agreement.

The patient is placed in the supine position on the operating table so that the affected leg is elevated (Fig. 28-5). The foot of the surgical bed is adjusted to allow 90° of knee flexion. A tourniquet and leg holder are used, but the tourniquet is inflated only for the initial exposure. The leg holder is placed at the middle of the thigh, which allows an assistant to open the tibiofemoral compartment under maximum tension for visualization and meniscus surgery. The extremity is draped free to allow easy positioning during surgery. Standard medial and lateral patellar arthroscopic portals, placed directly adjacent to the patellar tendon, are used for the diagnostic arthroscopy. A common mistake is to place the arthroscopic portals too far medially or laterally over the femoral condyles, where instrument passage damages the femoral articular cartilage. The safe area for instrument passage is with the portal just medial and lateral to the patellar tendon with passage into the femoral notch region.

FIGURE 28-5 Operating room setup for meniscus repair. A figure-four position for a lateral meniscal repair is shown with the assistant seated with a headlight to grasp the inside-out sutures.

Diagnostic arthroscopy is performed and the meniscus tear analyzed according to its location, type, and size. The meniscus tissue and synovial junction are rasped to stimulate bleeding at the meniscus-synovium border. Loose, unstable meniscus fragments are removed. In bucket-handle tears, the meniscus rim is prepared before the displaced meniscus is reduced because there are often fragments or partial horizontal clefts in the rim preventing close apposition of the meniscus body to the meniscus rim. Once the synovial fringe and meniscal edges are roughened, the meniscus tear is reduced anatomically. The goal is to restore the meniscus to its original size and shape to promote healing and restore its normal hoop stresses and biomechanical properties.

The inside-out meniscus repair technique requires an accessory posteromedial or posterolateral incision. This exposure allows protection of the neurovascular structures during suture retrieval and knot tying. In the authors’ opinion, an outside-in repair does not allow for the meticulous placement of vertical divergent sutures required for a meticulous meniscus repair for complex and avascular repairs, although it may be adequate for a peripheral meniscus repair. The outside-in–directed needle cannot be controlled adequately to position the sutures along the tear site. Rather, the meniscus tear is only approximated, which reduces the healing capabilities and success rates.

Exposure for Medial Meniscus Repair

With the surgeon seated, using a headlight, and the sterile prepared foot in the surgeon’s lap, the knee is flexed to 60° and a 3-cm vertical skin incision is made just posterior to the superficial medial collateral ligament (SMCL; Fig. 28-6). The tourniquet is inflated for the surgical exposure. The incision is centered just below the joint line (one third above, two thirds below) to allow retrieval of sutures. Avoid placing the incision too posterior in order to protect the saphenous vein and nerve. The subcutaneous dissection proceeds from the superior aspect of the wound down to the fascia. Care must be taken in the inferior aspect of the wound to avoid damage to the saphenous vein and nerve. Two retractors are used to provide visualization of the next layer of structures, the crural fascia and sartorius.

FIGURE 28-6 The accessory posteromedial approach is shown for a medial meniscus repair. A, Site of the posteromedial skin incision. B, The incision is shown through the anterior portion of the sartorius fascia. C, The interval is opened between the posteromedial capsule and the gastrocnemius tendon, just proximal to the semimembranosus tendon (arrow). The fascia over the semimembranosus tendon is excised to its tibial attachment to facilitate retrieval of the posterior meniscus sutures.

The anterior sartorial fascia is incised, avoiding the sartorius muscle. The pes muscle group is retracted posteriorly. The infrapatellar bundles of the saphenous nerve are identified to avoid injury. The retractors are repositioned to expose the posterior capsule and the semimembranosus sheath and tendon attachments. The key step is to incise the sheath overlying the semimembranous tendon. This opens a window to visualize the medial gastrocnemius tendon. Often, a small synovial Baker cyst is encountered in this interval, which is easily excised. The interval between the medial gastrocnemius tendon and the posterior capsule is bluntly dissected. This plane is developed superior to the semimembranosus tendon. This may be difficult because the semimembranosus tendon may be partially adhered to the posterior capsule. In some knees, the oblique popliteal ligament attachment to the semimembranosus tendon is partially incised to allow the tendon to be posteriorly displaced for exposure and suture retrieval.

Blunt dissection with an index finger allows development of a plane between the medial gastrocnemius tendon and the posterior capsule. A Henning retractor or spoon is inserted, allowing safe suture placement and needle retrieval (Fig. 28-7). The anesthesiologist is asked to provide muscle relaxation so that the gastrocnemius and semimembranosus muscles can be retracted. If the exposure is inadequate at this point, an alternative approach is to further dissect the semimembranosus tendon, which is elevated proximally to gain exposure just distal to the tendon. This is a less ideal approach because it is necessary to avoid placing sutures through the semimembranosus tendon just above its tibial attachment site.

FIGURE 28-7 Cross-section shows popliteal retractor between the capsule and the medial gastrocnemius. The suture cannula is placed through the lateral or medial portal with care taken to angle the needle away from the neurovascular structures.

Exposure for Lateral Meniscus Repair

The tourniquet is inflated and the surgeon seated using a headlight with the sterile prepared foot in the surgeon’s lap. The knee is flexed to 60° and a 3-cm skin incision is made just behind the fibular collateral ligament (FCL; Fig. 28-8). The incision is centered just below the joint line (one third above, two thirds below) to allow retrieval of sutures. The interval between the biceps tendon insertion and the iliotibial band is identified and incised, staying superior to the biceps short head muscle fibers. The fascia overlying the posterolateral structures and FCL is gently dissected and peeled from superior to the fibular head. This is performed by applying tension with forceps to the incised fascia and using a thin-blade scissors to peel and strip the fascial tissues to the head of the fibula, protecting the FCL. The retractors are positioned between the biceps tendon and the iliotibial band. The deep layer consists of the posterior capsule and the lateral gastrocnemius tendon. The gastrocnemius tendon has a normal proximal attachment to the posterior capsule, making it necessary to gently dissect the tendon with scissors off the posterior capsule at the joint line. The peroneal nerve inferior to the biceps tendon is palpated and protected, but is not dissected.

FIGURE 28-8 A, Site of the posterolateral incision for a lateral meniscus repair.

The surgeon must be careful to remain posterior to the FCL and other posterolateral structures. The key step is to initially enter the space anterior to the lateral gastrocnemius tendon just above the fibular head. This avoids penetrating and opening the posterior capsule. The space between the posterolateral capsule and the lateral gastrocnemius tendon is further developed bluntly with the index finger. A Henning retractor is used to push the neurovascular bundle medially (Fig. 28-9). The inferior lateral geniculate artery may be visualized in the inferior aspect of the exposure and may be damaged and require electrocoagulation (which is avoided if possible to maintain the vascular supply to the lateral meniscus). The retractor must always be positioned anterior to the gastrocnemius muscle and tendon and directly posterior to the posterior capsule and posterior meniscus bed. The retractor blocks the suture needles from passing too posterior and potentially injuring the common peroneal nerve. During the meniscus suture steps, the surgeon should frequently check the position of the retractor to always ensure that it is anterior to the gastrocnemius muscle. If the retractor is mistakenly placed posterior to the gastrocnemius muscle, the peroneal nerve may be injured.

FIGURE 28-9 Cross-section shows popliteal retractor between the lateral gastrocnemius and the posterior capsule. A curved suture cannula is also used to angle the needles away from the neurovascular structures.

Patient Positioning and Equipment for Inside-Out Suture Repair

An assistant sits in a chair on the medial or lateral side of the knee with a headlight to visualize the posterior meniscus and capsule penetration of the inside-out–directed suture needles. The assistant has a needle holder to catch the suture needles and suture scissors. An inverted clamp is attached to the drapes to act as an instrument holder for this equipment. A scrub nurse stands opposite the surgeon to pass sutures through the single cannula, one at a time, after the surgeon has positioned the cannula. An assistant holds the lower leg with the knee at 20° to 30° of flexion and applies the force required to open the tibiofemoral compartment. The articular cartilage is carefully protected at all times to avoid damage.

Instruments required in addition to routine arthroscopic equipment are a ball-tipped rasp for synovial rasping, a Henning or similar popliteal retractor for protection of the posterior neurovascular structures, a single-barrel straight and curved cannula for suture passage, and 10-inch double-armed meniscal sutures. Nonabsorbable sutures are used for interbody tears.

Suture Repair Techniques

For medial meniscus repairs, the knee is flexed 30° and an abduction load is applied. A 30° arthroscope is positioned through the medial portal to visualize the meniscus. The cannula is positioned through the lateral portal and pointed to the exact location of suture placement. This allows the suture needle to angle away from the midline neurovascular structures. Occasionally, the tibial spines block access for the suture cannula and the surgeon must place the suture cannula in the medial portal. The suture cannula with a large radius curve is selected to angle the needle away from the neurovascular structures posteriorly. The second assistant passes a 10-inch flexible needle through the cannula. The first assistant, seated on the medial side of the knee, catches the needle with the needle holder as it exits through the exposed meniscus bed. The next suture is passed in the same manner. The first assistant catches the double-armed needles and pulls the suture through. Both needles are cut, and the suture is tied with five knots. The surgeon closely observes the reduction of the meniscus body and closure of the tear site with passage and tying of the vertical divergent sutures. The next sutures are placed in a similar fashion. Vertical divergent sutures are alternated; the sutures are placed, first, on the superior surface to reduce the meniscus and, second, on the inferior surface to close the inferior tear.

The neurovascular structures are protected throughout the procedure with the appropriate posteromedial exposure and a Henning retractor. For tears of the medial meniscus that extend entirely to the posterior horn, the surgeon must always place the needle cannula in the lateral portal to angle the sutures away from the neurovascular structures.

For lateral meniscus repairs, the first assistant is seated on the lateral side of the knee, and an adduction stress is applied to the flexed knee. Otherwise, the positioning and technique are the same as those described for the medial meniscus repair.

Multiple 2-0 braided polyester nonabsorbable sutures (Ticron, Davis and Geck Co., Danbury, CT; or Ethibond, Ethicon Inc., Somerville, NJ) are used on a 10-inch straight cutting needle to repair all meniscus tears. The sutures are inserted through the superior and inferior meniscal surfaces in an interrupted vertical fashion to close the meniscus tear both superiorly and inferiorly. The vertical placement is used owing to its higher failure strength than that of horizontally placed sutures.¹¹¹ In addition, the vertical suture orientation mimics the function of the radial collagen fibers within the meniscus, which can improve its load-carrying capacity.²⁹

In addition, a single-barrel straight or curved arthroscopic cannula is used that allows for accurate placement of the sutures along the edge in tissue that will hold the stitches. A double-barrel cannula is not advocated, because the distance between the barrels is insufficient and needle control is compromised. The location of sutures depends on the tear pattern to be described.

Single and Double Longitudinal Tears

Only select double longitudinal tears are repaired; those with a peripheral meniscal-capsular disruption and those in which the second tear is at or close to the red-white junction. A tear entirely within the central meniscus third is only 6 to 7 mm in width and is not repaired. A longitudinal tear of the anterior horn of the medial or lateral meniscus that is at the periphery or extends into the red-white junction that fulfills the repair criteria is occasionally encountered. The senior author performs a mini-open direct 2- to 3-cm incision for an open repair. An outside-in placement of sutures for a simple tear is a second option.

A double-stacked suture technique is used for single and double longitudinal meniscus tears. This technique consists of two layers of sutures (Figs. 28-10 and 28-11) placed at 3- to 4-mm intervals along the length of the tear. The first layer of sutures is placed superiorly to anchor the meniscus to its bed and prevent superior migration of the meniscus during the repair. The cannula is used to hold and reduce the torn meniscus on the tibia.

FIGURE 28-10 Double-stacked vertical suture pattern used in the repair of longitudinal meniscus tears. A, The superior sutures are placed first to close the superior gap and to reduce the meniscus to its bed. B, Then, the inferior suture is placed through the tear to close the inferior gap.

FIGURE 28-11 A 35-year-old woman 20 years after a repair of an avascular 15-mm longitudinal medial meniscus tear involving the posterior horn. An inside-out technique with multiple vertical sutures was performed. The tear extended from the red-white to white-white region, with a 4- to 6-mm meniscus rim. A, The patient is entirely asymptomatic and participates in recreational activities. B and C, A 3-Tesla MRI shows an intact medial meniscus and normal-appearing articular cartilage. D, T₂-weighted cartilage mapping shows no definite abnormality.

The first pass of the double-armed suture is placed in the meniscal-synovial junction (periphery) of the intact portion of the meniscus. The second pass of the double-armed suture is placed through the torn portion of the meniscus in a vertical plane so that it bridges the tear (Fig. 28-12). The inferior sutures are placed next in a vertical plane, crossing the tear in the same manner as the superior sutures. The sutures are brought out through the accessory incision and tied directly over the posterior meniscal attachment and capsule. The sutures are tied as they are passed to determine the apposition of the tear surfaces. The tension in each suture is confirmed arthroscopically after the knot is tied. This double-stacked technique provides stable fixation of the meniscal tear on both sides and entirely closes the meniscus gap at the repair site (Fig. 28-13).

FIGURE 28-12 Double-stacked repair technique for double longitudinal tears. The peripheral tear is repaired first with superior and inferior vertical divergent sutures (A), followed by repair of the inner tear in the same fashion (B).

FIGURE 28-13 A longitudinal meniscal tear site demonstrates some fragmentation inferiorly. This tear required multiple superior and inferior vertical divergent sutures to achieve an anatomic reduction.

(Reprinted with permission from Noyes, F. R.; Barber-Westin, S. D.: Arthroscopic repair of meniscal tears extending into the avascular zone in patients younger than twenty years of age. Am J Sports Med 30:589–600, 2002.)

Double longitudinal meniscus tears require an additional set of sutures. The peripheral tear is repaired in the same manner as a single longitudinal tear with superior and inferior sutures. The longitudinal tear located in the middle body is repaired with two or three additional superior and inferior sutures. Care is taken to avoid excessive suture placement between tears in order to maintain meniscus integrity and function.

Radial Tears

Horizontal sutures are placed at 2- to 4-mm intervals along the tear to repair radial meniscus tears. The inner sutures are placed first and securely tied, followed by sutures located in the periphery (Fig. 28-14). Three to four sutures are used on the superior surface, and one or two sutures are used on the inferior surface. The initial sutures are placed first through the body using the needle to place the meniscus toward the tear site, followed by needle passage through the meniscus bed. This allows the tear site gap to be closed. Only radial tears that extend to the outer third of the meniscus body are repaired, because those that are confined to the inner and middle zones have a poor blood supply and will not heal. A radial tear that extends to the meniscus rim compromises the hoop stress and is equivalent to a total loss of meniscus function. Occasionally, the edges of the radial tear are degenerative with poor suture-holding capability and repair is not possible. Traumatic radial tears have a better chance of healing. The goal is to retain partial meniscus function, if possible, because it is rare to have successful healing of a tear in the inner aspect of the meniscus. Because only a limited number of sutures are used, the holding strength is low and a period of non–weight-bearing for 4 weeks is required to prevent disruption of the repair site. The patient is advised that this type of repair has a guarded prognosis in terms of providing function. The repair may heal, but the meniscus tear edges separate in the healing process with the interval replaced with poorly organized fibrous tissue with an elongated meniscus structure that displaces from the joint.

FIGURE 28-14 Repair technique for radial meniscal tears. The inner sutures (A) are placed first, followed by the peripheral sutures (B). The first suture needle is placed midway through the meniscus body and then used to apply a circumferential tension to reduce the tear gap, then advanced through the posterior meniscus bed. The second suture needle is placed in a similar manner. This reduces the radial gap, allowing subsequent sutures to be placed. Usually, 3 to 4 sutures are placed superiorly and two sutures, inferiorly. C, Occasionally, superior vertical divergent sutures are placed along the tear site to help stabilize the repair.

Lateral Radial Tears Associated with a Cyst

Because partial meniscectomy and cyst excision may remove a substantial portion of the meniscus body and disrupt its peripheral rim, a cyst should be excised through a limited open lateral exposure (Fig. 28-15). This is followed by repair of the peripheral rim of the meniscus using an open technique. Then, the radial tear and any associated horizontal tears may be repaired using the arthroscopic techniques described previously. It is not recommended to evacuate the cyst through the intra-articular radial tear site because this damages meniscus tissues and prevents repair. A lateral meniscus cyst is commonly associated with combined radial and horizontal tears that are not reparable; however, this is difficult to determine preoperatively. The mistake is to excise the meniscus in a patient 50 years of age or younger in whom a repair is possible to preserve some meniscus function where progression to lateral compartment arthritis occurs in a short time, particularly in a valgus-aligned lower extremity.

FIGURE 28-15 Demonstration of repair of lateral meniscus horizontal tear with a meniscal cyst. A, A 3-cm lateral joint incision placed directly over cyst shows the iliotibial band and an obvious protruding cyst. B, Iliotibial band is split in a line of fibers over the cyst and retracted, the cyst is removed, and repair is performed of the remaining meniscus to the attachments. C, Closure of the iliotibial band over the meniscus. Vertical sutures placed through the peripheral meniscus and iliotibial band help stabilize the repair. Then the arthroscopic inside-out repair of the meniscus body tear is performed.

Horizontal Tears

The majority of horizontal tears are degenerative with poor tissue quality and are not reparable. These irreparable tears have thickened tissues, fatty deposition, and partial flap tears. Occasionally, a large horizontal flap tear is encountered in patients younger than 50 years of age in which the tear extends throughout the body creating superior and inferior segments, but the meniscal tissue is of good quality, has not displaced outside the tibiofemoral compartment, and can be repaired. The meniscus is rasped through the superior and inferior synovial attachments and within the horizontal tear. Minor meniscus fragments are removed. Vertical divergent sutures are used to close the tear site. The soft Ethibond sutures are preferred that, by experience, do not damage articular cartilage. A fibrin clot may be added to the repair site, placed within the horizontal tear. However, whether or not this technique increases the repair success rate has not been scientifically proved.

Meniscus Attachment Root Tears

An important reparable meniscus tear is one in which the posterior horn is torn directly at its posterior attachment, producing a complete loss of meniscus function as it displaces under weight-bearing loads. Instruments used in shoulder rotator cuff tears can be used to pass two mattress-type sutures for firm fixation of the meniscus (Fig. 28-16). Alternatively, a suture lasso instrument can be passed through a small tibial tunnel. The suturing instrument is passed twice through the medial or lateral portal using a cannula. The mattress suture is performed rather than a single throw of the suture to increase holding strength. A leg holder is required to allow sufficient joint opening for passing and using the suture device, particularly for medial meniscus root tears. Without suturing, the tear results in complete loss of meniscus function. A 4- to 5-mm tibial tunnel using an ACL tibial guide is placed directly at the attachment site. The sutures are tied over a tibial post. Weight-bearing is restricted for 4 weeks.

FIGURE 28-16 Posterior meniscus root attachment tear: Demonstration of the use of the Scorpion (Arthrex, Naples, FL) suture-passing device. A, Placement of two mattress sutures; the device can be passed in and out of the portal to place higher–holding strength mattress sutures over a single suture. B, Final placement of sutures brought out through a 4-mm transtibial tunnel and tied over a post to restore meniscus attachment.

Flap Tears

Two sets of sutures are required to repair flap tears (Fig. 28-17). Tension sutures are inserted first through the flap and then into the intact meniscal rim to anchor and reduce the flap into its anatomic bed. This restores the longitudinally running fibers of the meniscus and is performed in a manner similar to that for a radial tear repair. With the meniscus reduced, the remaining tear is repaired in the same fashion as a longitudinal tear, with superior and inferior vertical divergent sutures. The radial portion of the flap tear may only partially heal; however, the more peripheral longitudinal tear may heal, retaining partial meniscus function. Flap tears that represent 75% of the meniscus with the tear at the periphery or red-white junction are amenable for repair. Smaller flap tears 10 to 12 mm in length that occupy the red-white and white-white zones are not repaired.

FIGURE 28-17 Repair technique for flap tears. A, The tear is identified and reduced. B, Horizontal tension sutures are placed to anchor the radial component of the tear. C, The longitudinal component is sutured using the double-stacked suture technique.

Repair of the Lateral Meniscus Popliteomeniscal Fascicles and Attachments

At arthroscopy, a nerve hook is placed at the superior and then inferior popliteal hiatus to displace the lateral meniscus anteriorly and superiorly. The knee joint is placed in 60° to 90° of flexion with a figure-four varus load applied to allow lateral tibiofemoral joint opening and maximum meniscus displacement (which is otherwise obstructed by the lateral femoral condyle). The posterior horn may be subluxated anteriorly 8 mm or more (usually not enough for locking into the joint) and superior “lift-off ” of 10 to 12 mm is usually present, indicating laxity of the meniscotibial attachments. There is usually a tear of the meniscotibial attachments in which the normal inferior popliteal hiatus is enlarged with attenuation or tearing of the meniscus attachments.

The repair of the popliteomeniscal fascicles requires a meticulous inside-out technique with multiple sutures to obtain stability of the lateral meniscus and alleviate clinical symptoms. All-inside meniscus fixators or use of only a few sutures is not suitable to provide a stable construct and repair. The arthroscope is placed in the lateral portal and the suture cannula in the medial portal. The superior and inferior sites are rasped to encourage healing. The inside-out meniscus repair technique requires placement of multiple vertical divergent sutures, placed superiorly at the anteroinferior and posterosuperior fascicle attachments (either side of the popliteus tendon) to reduce the lateral meniscus posterior horn to a normal tibial position and restore the meniscus attachments.

The more difficult repair involves inferior vertical divergent sutures at the inferior popliteal hiatus and meniscotibial meniscus attachments. The tissues may be thin and four to six sutures must be placed through the inferior capsule at the level of the tibial attachment, and then in a vertical manner through the inferior outer third of the meniscus posterior horn. It is important that the previously placed superior vertical sutures retain the meniscus reduction so that placement of the inferior sutures does not displace the meniscus in an abnormal cephalad direction.

Techniques to Stimulate Healing of Meniscus Repairs

The initial vascular response of the meniscus to injury and tearing is characterized by the formation of a fibrin clot that is rich in inflammatory cells. This clot acts as a scaffold through which cells from the synovial membrane adjacent to the meniscus migrate.^7,8 The meniscal fibrochondrocytes may add to the intrinsic healing process.

Several experimental studies have investigated techniques to stimulate meniscus healing, including trephination or vascular ingrowth,^8,46,149,150 abrasion of the meniscal-synovial region,^51,93,112 grafting of the synovial pedicle,⁴⁷ incorporation of a fibrin clot,^93,112 and use of growth factors and cell-based therapy.* Although trephination, or creation of vascular access channels, has been demonstrated experimentally to promote healing, the creation of these channels disrupts the normal peripheral structure of the meniscus. Investigations of growth factors and cell-based therapies have all been experimental to date, with no published clinical trials to document the potential effectiveness.

The incorporation of a fibrin clot⁵² at the repair site is theoretically beneficial because it provides a scaffold to support the reparative cells and provide chemotactic and mitogenic stimuli.¹⁴⁴ The absence of a well-defined fibrin clot in the initial healing period along with a limited vascular supply may be the most important factors limiting meniscus healing in tears located in the middle third region. The problem is that a fibrin clot inserted between the tear edges of the meniscus prevents meticulous suturing of the tear both superiorly and inferiorly. A fibrin clot may be beneficial in horizontal tears in which the clot may be placed between the superior and the inferior tear sites. The clot is prepared with a glass stirring rod. The clot is passed into the knee joint through a cannula, guided by a loop of suture placed around the clot from previously passed meniscus suture needles.

Ritchie and coworkers¹¹² found that abrasion of the parameniscal synovium was more effective than the incorporation of a fibrin clot in central meniscus repairs. Synovial abrasion stimulates vessels and mesenchymal cells to form a proliferate vascular pannus that migrates into the repair site.^35,50,123

Several studies have demonstrated that an ACL reconstruction performed concomitantly with meniscal repair increases the success rate because the reconstruction protects the meniscus repair site owing to the restored knee stability and provides the beneficial healing effects of the postoperative hemarthrosis.^{33,36,60,91,134} In the majority of meniscus repairs done without concomitant ACL reconstruction, the meniscal-synovial junction is abraded and a micropick used in the intercondylar notch region to produce bleeding that promotes adherence of platelets and fibrin at the repair site. The meticulous suture placement described in this chapter stabilizes the tear and prevents gap formation at the repair site, allowing the subsequent repair process to progress.

The remodeling events and extent of reformation of a normal collagen architecture after meniscus repair remain unknown. Whether repaired meniscal tears in the middle third region have normal load-sharing capabilities and mechanical and material properties to prevent joint arthrosis remains unanswered. In the future, specific chemotactic and mitogenic agents may play an important role in stimulating the repair process of tears that extend into the avascular portions of the meniscus.

Arthroscopic Assessment of Meniscus Repairs in the Outer and Middle Third Regions

An investigation was conducted on 66 patients who underwent a concomitant meniscus repair and ACL reconstruction, then follow-up arthroscopy 6 to 25 months postoperatively.³¹ There were a total of 79 meniscus repairs; 51 were done for tears located in the outer third region (periphery) and 28 were done for complex tears that extended into the middle third avascular region. Follow-up arthroscopy was indicated for symptoms related to either tibial hardware or tibiofemoral joint pain.

All patients were placed into a postoperative rehabilitation program that included immediate knee motion exercises the 1st postoperative day. During the time period of this study (1983–1988), knee motion was limited to 20° to 90° for the first 4 weeks, with full extension then achieved by the 8th postoperative week. Early partial weight-bearing was initiated between the 1st and the 3rd postoperative weeks and was progressed to full by the 8th to 10th week. Postoperative strengthening exercises were initiated on the 2nd postoperative day and included patellar mobilization, straight leg raises, isometrics, and electrical muscle stimulation.

Critical Points AUTHORS’ CLINICAL STUDIES: ARTHROSCOPIC ASSESSMENT OF MENISCUS REPAIRS IN THE OUTER AND MIDDLE THIRD REGIONS

• N = 79 meniscus repairs: 51 tears located in outer third region, 28 extended into middle third region.

• All had anterior cruciate ligament reconstruction with meniscus repair.

• Follow-up arthroscopy average 12 mo (range, 6–25 mo) after repair.

• Healing rates

Outer third: 94% healed, 4% partially healed, 2% failed.

Middle third: 54% healed, 32% partially healed, 14% failed.

• No effect on meniscus repair healing rates: length of meniscus tear, tibiofemoral compartment of repair, patient age, length of time from injury to repair, length of follow-up, arthroscopic vs. open procedure.

• Use of immediate knee motion and early weight-bearing not deleterious to healing meniscus repair.

The arthroscopic videotapes and operative records were reviewed by a surgeon who had not been involved in the care of the patients. The rate of meniscus healing was classified as either completely healed (no visible surface defect), partially healed (at least 50% healed with meniscus stability and continuity restored), or failed (no visible healing). The effects of rim width, length of the tear, tibiofemoral compartment, patient age, length of time from injury to repair, length of follow-up, and arthroscopic versus open procedure were analyzed on the healing rates. The three healing categories were analyzed separately, and then the categories of healed and partially healed were combined and this category (retained meniscus) was compared with the failure rates.

Repairs of tears located in the outer third region were classified as completely healed in 94%, partially healed in 4%, and failed in 2% (Table 28-1). Repairs of tears that extended into the avascular region were classified as completely healed in 54%, partially healed in 32%, and failed in 14%. The other factors analyzed in this study had no significant effect on the healing rates.

The use of immediate knee motion and early weight-bearing was not deleterious to the healing meniscus repairs. Upon the completion of this study, the postoperative program was adjusted to allow full extension the 1st postoperative day in all patients undergoing meniscus repairs. This was one of the first investigations to demonstrate that repair of meniscus tears located in either the outer third or that extended into the middle third region have a satisfactory rate of healing when clinical grounds warrant the procedure.

The increase in healing of meniscus tears with concurrent ACL surgery is well appreciated. In knees that undergo meniscus repairs without ACL surgery, the femoral notch region is trephinated to induce joint bleeding and potentially aid in the deposition of blood products at the healing site for the initial fibrin clot formation.

Outcome of 198 Meniscus Repairs in the Middle Third Region

The clinical outcome of 198 meniscus tears that extended into the middle third region, or that had a rim width of 4 mm or greater, was determined in a prospective study.¹²¹ Either a clinical examination a minimum of 2 years postoperatively or follow-up arthroscopy were used for inclusionary criteria. The 198 meniscus repairs were performed in 177 patients. Of these, 180 repairs (91%) were evaluated with a clinical examination a mean of 42 months (range, 23–116 mo) postoperatively. In addition, 91 repairs (46%) were evaluated with a follow-up arthroscopic examination a mean of 18 months (range, 2–81 mo) after the initial repair.

Seventy-six of the meniscus repairs were performed for acute or subacute tears and 122 for chronic tears. ACL ruptures also occurred in 128 patients. Of these, 126 (71%) underwent ACL reconstruction either with the meniscus repair (96 patients) or a mean of 22 weeks after the repair (30 patients). The ACL reconstructions were done with allografts in 72 knees and with bone–patellar tendon–bone (B-PT-B) autografts in 54 knees. After surgery, patients began immediate knee motion from 0° to 90°. Flexion was advanced to 125° by the 3rd postoperative week. Crutches were used for the first 4 weeks for longitudinal tears and for the first 6 weeks for horizontal, radial, or complex multiplanar tears. Squatting or deep knee flexion greater than 125° was not permitted for 4 to 6 months postoperatively. Full sports activity was restricted for 6 months.

At follow-up arthroscopy, the meniscus repairs were classified as healed if full-thickness apposition of the original tear occurred with no more than 10% of the original tear remaining. Repairs were considered partially healed if at least 50% of the original tear was healed and was stable when probed and the meniscus body was in its normal position in the tibiofemoral joint. Repairs were considered failed if more than 50% of the original tear was present or if unstable fragments required additional sutures. On clinical examination, a McMurray test was used with joint line palpation and compression to detect tibiofemoral joint symptoms.

Critical Points AUTHORS’ CLINICAL STUDIES: OUTCOME OF 198 MENISCUS REPAIRS IN MIDDLE THIRD REGION

• N = 198 meniscus repairs in 177 patients.

• 71% had anterior cruciate ligament reconstruction either with or after meniscus repair.

• 91% evaluated clinically 23–116 mo postoperatively.

• 46% evaluated follow-up arthroscopy 2–81 mo postoperatively.

• Advanced rehabilitation program allowed 0°–90° of knee motion immediately postoperatively.

• Deep knee flexion, full sports delayed for 6 mo to protect repair site.

• Overall reoperation rate for tibiofemoral symptoms: 20%.

• 80% asymptomatic for tibiofemoral symptoms, not interpreted as rate of healing.

• Significant differences in healing rates in menisci evaluated with follow-up arthroscopy:

Higher rate of retention lateral meniscus compared with medial meniscus.

Higher rate of healing repairs assessed ≤12 mo compared with repairs assessed >12 mo with follow-up arthroscopy.

Higher rate of healing in knees without tibiofemoral joint symptoms compared with those with joint line pain.

• Results support repair of meniscus tears that extend into middle avascular region, especially in patients in their 20s and 30s.

The overall reoperation rate for tibiofemoral symptoms was 20% (39 meniscus tears). All patients who had tibiofemoral pain underwent follow-up arthroscopy. The reoperation rates according to the type of tear are shown in Table 28-2. The limited number of meniscal tears in the individual classification categories precludes specific conclusions on the outcome for each tear pattern. Of the 39 menisci examined, 2 were classified as healed, 13 as partially healed, and 24 as failed. The reoperation rates for tibiofemoral joint symptoms were 12% for single longitudinal tears, 28% for double longitudinal tears, and 27% for the most difficult complex multiplanar tears.

TABLE 28-2 Reoperation Rates for Meniscal Repairs due to Tibiofemoral Joint Symptoms

A total of 91 meniscus repairs were evaluated by follow-up arthroscopy; the 39 described above and 52 others that underwent surgery for reasons other than tibiofemoral joint symptoms. Of these 91, 23 (25%) were classified as healed, 35 (38%) as partially healed, and 33 (36%) as failed.

The effect of six factors on healing rates of meniscal repairs was evaluated (Table 28-3). Statistically significant differences were found in the rates of healing for three factors: tibiofemoral compartment of the meniscus repair (higher healing rate in lateral meniscus repairs than in medial meniscus repairs), time from repair to follow-up arthroscopy (higher healing rate in patients evaluated ≤12 mo compared with those evaluated >12 mo postoperatively), and the presence of tibiofemoral symptoms (higher healing rate in asymptomatic patients than in symptomatic patients). A trend (P = .06) was observed for the factor of time from the original knee injury to the meniscus repair (higher healing rate in patients operated on ≤10 wk than in those operated on >10 wk after the injury).

Menisci examined with arthroscopy greater than 1 year postoperatively had a higher rate of tibiofemoral joint symptoms and failed repairs than those examined less than 1 year postoperatively. The average time from the repair to the follow-up arthroscopy in the 39 menisci with tibiofemoral symptoms attributed to a failed repair was 24 months (range, 3–81 mo). Of these 39, 25 (64%) had an interval longer than 12 months between procedures. Of the 33 menisci proven failed by follow-up arthroscopy, 21 (64%) had an interval of greater than 1 year between procedures: 15 were between 1 and 3 years, and 6 were between 3 and 5 years after repair.

There was no statistical difference in the rate of meniscus healing or in the percentage of menisci that required follow-up arthroscopy when an ACL reconstruction was performed concurrently or after the meniscus repair. There was also no difference between the reoperation rate and the function of the ACL graft as determined by arthrometer and pivot shift testing.

The significantly higher rate of retention of lateral meniscus repairs found in this study agrees with those of other reports.^91,120,123 The reasons for the higher failure rate of medial meniscus repairs are unknown at present. The results of this investigation support the repair of meniscus tears that extend into the middle avascular region, especially in patients in their 20s and 30s and highly competitive athletes. The study’s reoperation rate should not be interpreted as the rate of meniscal healing. The long-term function and chondroprotective effects of the repaired menisci need to be determined, and this group of patients is under prospective long-term evaluation.

Outcome of Meniscus Repairs in the Middle Third Region in Patients 40 Years of Age and Older

The clinical outcome of meniscus tears that extended into the avascular region in patients 40 years of age and older was prospectively determined.⁹⁷ Thirty of 31 consecutive meniscus repairs in 29 patients were followed by either clinical examination or arthroscopy after the initial repair. A clinical evaluation was conducted in 27 patients (28 meniscus repairs) a mean of 34 months (range, 23–71 mo) postoperatively. Six repairs were evaluated with arthroscopy a mean of 24 months (range, 16–36 mo) after the repair.

ACL reconstruction was performed at the time of the meniscus repair in 21 patients (72%). Ten meniscus repairs were done for acute knee injuries (≤10 wk from injury) and 20 were done for chronic injuries.

At follow-up arthroscopy, the meniscus repairs were classified as healed if full-thickness apposition of the original tear occurred with no more than 10% of the original tear remaining. Repairs were considered partially healed if at least 50% of the original tear was healed, it was stable when probed, and the meniscus body was in its normal position in the tibiofemoral joint. Repairs were considered failed if more than 50% of the original tear was present or if unstable fragments required additional sutures. On clinical examination, a McMurray test was used with joint line palpation and compression to detect tibiofemoral joint symptoms.

At follow-up, 26 meniscus repairs (87%) both were asymptomatic for tibiofemoral joint symptoms and had not required further surgery (Table 28-4). There was no significant effect of the tibiofemoral compartment of the meniscus repair, chronicity of injury, concomitant ACL reconstruction, or condition of the articular cartilage on the presence of tibiofemoral pain or meniscus resection (Table 28-5).

A subjective evaluation using the Cincinnati Knee Rating System was completed at follow-up on 25 knees; 3 knees whose meniscal repairs failed and required removal at follow-up arthroscopy and 1 other knee that had follow-up arthroscopy but not a clinical evaluation 2 years postoperatively were not included. Of these 25 knees, 17 had chronic meniscal tears and 8 had acute tears before the index repair procedure. Nineteen had a concomitant ACL reconstruction.

The 17 knees with chronic symptoms had statistically significant improvements at follow-up in the mean scores for pain, swelling, and giving-way (P < .01). The mean preoperative pain score of 4.4 improved to 7.1, and the mean preoperative giving-way score of 5.9 improved to 8.8 (scale, 0–10). These knees also had significant improvements in the mean scores for squatting (P < .05), running, jumping, and cutting (P < .0001).

Before the meniscal repair, patients with 12 of the knees with chronic injuries had given up sports and 5 were participating with symptoms and functional limitations. At follow-up, 12 had returned to sports without problems, 1 was participating with symptoms, and 4 had not returned to sports owing to the knee condition. In the patient rating of the overall knee condition, 11 rated their knees as normal or very good; 3, good; 2, fair; and 1, poor.

Seven of the 8 patients with an acute injury were involved in athletics prior to their injury. The 1 patient who was not involved in athletics returned to normal activities of daily living without symptoms. Six patients returned to athletics without problems. Only 1 patient reported difficulty with squatting, and 1 patient had problems with running, jumping, and cutting. All 8 patients rated their overall knee condition as normal or very good.

There were no infections, knee motion problems, saphenous neuritis, or other major complications.

With many patients remaining active in middle age, the ability to retain the meniscus after an injury is an important goal. The treatment of tears that extend into the middle third avascular zone represents a problem in these patients. Usually, these tears are removed to the extent at which the remainder of meniscal tissue is nonfunctional. This study demonstrated that repair of complex tears in older adults is feasible and that the majority are asymptomatic for tibiofemoral joint symptoms an average of 3 years postoperatively. In athletically active patients, the indications of meniscus repair are based on current and future activity levels and the authors recommend the preservation of meniscal tissue wherever possible regardless of age. It should be noted that the majority of meniscus tears in patients over 40 years of age are degenerative and not reparable. This group of select patients had tears that were classified as amenable to repair by the criteria already provided.

Outcome of Meniscus Repairs in the Middle Third Region in Patients Younger than 20 Years of Age

A prospective study was conducted on 71 of 74 consecutive meniscus repairs (96% follow-up) that had been done in 58 patients under the age of 20 to determine the clinical outcome.⁹⁶ Sixty-seven meniscal repairs were examined clinically a mean of 51 months (range, 24–196 mo) after the operation. Thirty-six menisci in 28 knees were evaluated during follow-up arthroscopy a mean of 18 months (range, 3–60 mo) postoperatively. Of these, only 4 menisci were not examined a minimum of 2 years postoperatively.

There were 36 males and 25 females whose mean age at the time of the meniscus repair was 16 years (range, 9–19 yr). Two patients were 9 years of age and the remainder were in the second decade. Skeletal maturity, according to closed or nearly closed physes on roentgenograms of the distal femur and proximal tibia, had been reached in 54 knees (88%). The mean time from the original injury to the meniscus repair was 40 weeks (range, 1–256 wk). Forty meniscal repairs were done for an acute knee injury (1–12 wk after the injury) and 31 meniscal repairs were done for a chronic knee injury.

Forty-three meniscal repairs (61%) in 36 knees were performed concurrently with an ACL reconstruction. Fourteen meniscal repairs (20%) were done in 11 knees a mean of 34 weeks (median, 4 wk; range, 4–176 wk) prior to an ACL reconstruction. Skeletal maturity had been completed in all knees that had ACL reconstructions.

At follow-up, 53 of 71 meniscal repairs (75%) had no tibiofemoral symptoms and had not been classified as failed on follow-up arthroscopy.

Fourteen meniscal repairs (20%) developed tibiofemoral joint symptoms; all but 1 of these had follow-up arthroscopy a mean of 19 months (range, 3–49 mo) postoperatively. One repair had healed and 4 had partially healed with small segments of the original tear requiring removal. Eight repairs had failed: 2 required removal at the prior repair site, 3 required near-total meniscectomy, and 2 had a repeat repair. In 1 knee that required a near-total lateral meniscectomy, a meniscus allograft was implanted.

Critical Points AUTHORS’ CLINICAL STUDIES: OUTCOME OF MENISCUS REPAIRS IN MIDDLE THIRD REGION IN PATIENTS YOUNGER THAN 20 YEARS OF AGE

• N = 71 meniscus repairs in 58 patients.

• 61% had anterior cruciate ligament reconstruction either with or after meniscus repair.

• 94% evaluated clinically 24–196 mo postoperatively.

• 51% evaluated by follow-up arthroscopy 3–60 mo postoperatively.

• 75% had no tibiofemoral symptoms or failed meniscus repair according to arthroscopic classification.

• Reoperation rates owing to tibiofemoral joint symptoms: 8% single longitudinal tears, 33% double longitudinal tears, 14% complex multiplanar tears.

• No effect on tibiofemoral joint symptoms or arthroscopic classification of failure: tibiofemoral compartment of meniscal repair (medial vs. lateral), chronicity of injury, concomitant anterior cruciate ligament reconstruction.

• Presence of tibiofemoral pain: sensitivity rate of 57%, specificity rate of 93% in identifying repairs classified as failed at follow-up arthroscopy.

• Knees with concomitant meniscus repair and ACL reconstruction

No problems with daily activities.

73% return to sports without problems.

87% rated overall knee condition as normal or very good.

No complications, arthrofibrosis.

• Presence of tibiofemoral pain not always indicative of a failed meniscus repair, consider magnetic resonance imaging before arthroscopy to determine source of pain.

• Results allow recommendation of repair meniscus tears that extend into middle third region when conditions indicate that stable repair can be obtained.

• This recommendation is particularly appropriate in young active individuals in whom removal of meniscus tear that extends into middle avascular region would result in major loss of meniscus function and risk for future joint arthrosis.

The reoperation rates due to tibiofemoral joint symptoms were 8% for single longitudinal tears, 33% for double longitudinal tears, and 14% for complex multiplanar tears. Twenty-three other meniscal repairs had follow-up arthroscopy for reasons other than tibiofemoral symptoms a mean of 17 months postoperatively (range, 7–60 mo). Twelve of these meniscal repairs had healed. Seven repairs had partially healed; in 5, partial meniscectomy was required, and in 2, the meniscal tears were deemed stable and left intact. Four of these 23 meniscal repairs (in 3 knees) failed. A lateral and a medial meniscus allograft were implanted 40 months and 42 months, respectively, after the index repair procedure in 1 knee. A repeat meniscus repair was done in 1 knee, and a partial meniscectomy at the prior repair site was required in another knee.

There was no statistically significant effect of the tibiofemoral compartment of the meniscal repair, chronicity of injury, or concomitant ACL reconstruction on the presence of tibiofemoral joint symptoms or arthroscopic classification of failure. The presence of tibiofemoral pain on the physical examination was found to have a sensitivity rate of 57% and a specificity rate of 93% (Table 28-6) in identifying meniscus repairs classified as failed or that required partial resection at follow-up arthroscopy. The positive predictive value was 92%, and the negative predictive value was 61%.

TABLE 28-6 Diagnostic Test Rates of Tibiofemoral Joint Pain on Clinical Examination in Identifying Failed Meniscal Repairs

Of the 45 knees that had a concomitant meniscal repair and ACL reconstruction, 26 (58%) had no pain, 34 (76%) had no swelling, and 38 (84%) had no giving-way with sports activities involving jumping, cutting, and pivoting at follow-up (Fig. 28-18). None of these knees had functional limitations with walking, stair-climbing, or squatting. Forty (89%) had no or only slight problems with running, jumping, and twisting.

FIGURE 28-18 Analysis of symptoms at follow-up (mean, 47 mo after the operation) for the 45 knees that had anterior cruciate ligament reconstruction and meniscus repair procedures.

(From Noyes, F. R.; Barber-Westin, S. D.: Arthroscopic repair of meniscal tears extending into the avascular zone in patients younger than twenty years of age. Am J Sports Med 30:589–600, 2002.)

Before the meniscus repair, 34 patients were participating in various types of athletic activities and 11 had given up sports owing to knee problems (Table 28-7). At follow-up, 33 (73%) had returned to athletics without symptoms or limitations, and 3 (7%) were participating in sports with symptoms against advice. Two (4%) had not returned to sports owing to the knee condition, and 7 (16%) had given up sports activities owing to factors unrelated to the knee condition. At follow-up, 39 (87%) rated the overall knee condition as normal or very good; 2 (4%), as good; 3 (7%), as fair; and 1 (2%), as poor.

TABLE 28-7 Sports Activities of Patients before the Meniscal Repair and at Follow-up*

* In 45 knees that had an anterior cruciate ligament reconstruction and a meniscal repair.

There were no instances of infection, accessory posteromedial or posterolateral incision pain, saphenous neuritis, or arthrofibrosis. Two patients who had a concomitant ACL reconstruction required a gentle manipulation under anesthesia for a limitation of knee flexion in the early postoperative period. At follow-up, all patients had at least 135° of flexion and 0° of extension.

The major limitations of this study were the inability to obtain objective data in all patients on meniscus healing and to determine the functional capabilities of the repaired menisci. Although follow-up arthroscopy and MRI provide an indication of meniscal healing and function, cost-containment issues preclude the use of these procedures in asymptomatic knees. This leaves clinical evaluation as the primary method for assessing meniscal healing after repair in the majority of cases.

In patients who had subsequent surgery, the sensitivity rate of the clinical tibiofemoral joint pain test was low (57%). The presence of tibiofemoral pain is not always indicative of a failed meniscus repair, and it can be difficult to determine the source or origin of this pain. The specificity rate was very high (93%), indicating that when no tibiofemoral pain was present clinically, there usually was no meniscal tear found during follow-up arthroscopy. The positive predictive value was also high (92%), indicating that when a meniscus tear was observed at arthroscopy, tibiofemoral pain would most likely be demonstrated clinically. When tibiofemoral pain is present, other diagnostic tests such as MRI are indicated to exclude other sources of pain prior to considering arthroscopy.

The results of this study allow recommendation of repair of simple or complex meniscal tears that extend into the avascular zone when the conditions are met that a stable repair of a potentially functional meniscus can be obtained. This recommendation is particularly appropriate in young active individuals in whom removal of a meniscus tear that extends into the middle avascular region would result in major loss of meniscus function and risk for future joint arthrosis.