Sports Medicine
SECTION 2 THIGH, HIP, AND PELVIS
SECTION 3 LEG, FOOT, AND ANKLE
V. Impingement Syndrome/Rotator Cuff Disease
VI. Superior Labral and Biceps Tendon Injuries
VII. Acromioclavicular and Sternoclavicular Injuries
section 1 Knee
1. Hinge joint that also incorporates both gliding and rolling, which are essential to its kinematics
2. See Chapter 2, Anatomy, for a thorough discussion of knee anatomy.
Anterior cruciate ligament (ACL)
Despite intensive research, the function and anatomy of the ACL are still debated.
Femoral attachment: semicircular area on the posteromedial aspect of the lateral femoral condyle (Figure 4-1)
Has two “bundles” named on the basis of tibial insertion:
Anteromedial: tight in flexion; primarily an anterior restraint; evaluated by Lachman and anterior drawer tests
Posterolateral: tight in extension; primarily a rotatory restraint; evaluated by pivot shift test
Composition: 90% type I collagen and 10% type III collagen
Mechanoreceptor nerve fibers within the ACL have been found and may have a proprioceptive role.
Posterior cruciate ligament (PCL)
Femoral attachment: broad, crescent-shaped area on the anterolateral medial femoral condyle
Tibial insertion: tibial sulcus below articular surface (see Figure 4-1)
Medial collateral ligament (MCL)
Lateral collateral ligament (LCL); also known as the fibular collateral ligament
Origin: lateral femoral epicondyle
Insertion: anterolateral aspect of the fibular head
Tight in extension and lax in flexion because of its location behind the axis of knee rotation
Deep and posterior to the superficial MCL, contiguous with the deep MCL
Increasingly important factor in the treatment of the multiple ligament injured knee
Originates on the back of the tibia
The femoral insertion is inferior, anterior, and deep to the LCL.
Arcuate ligament (which is contiguous with the oblique popliteal ligament medially)
Fabellofibular ligament (lateral two are really just thickenings of the joint capsule)
The PLC is the primary stabilizer of external tibial rotation.
4. Medial structures of the knee (three layers) (Table 4-1; Figure 4-2)
Table 4-1
| Layer | Components |
| I | Sartorius and fascia |
| II | Superficial MCL, posterior oblique ligament, semimembranosus |
| III | Deep MCL, capsule |
MCL, medial collateral ligament.
Note: The gracilis, semitendinosus, and saphenous nerves run between layers I and II.
5. Lateral structures of the knee (three layers) (Table 4-2; see Figure 4-2)
Table 4-2
Lateral Structures of the Knee
| Layer | Components |
| I | Iliotibial tract, biceps, fascia |
| II | Patellar retinaculum, patellofemoral ligament |
| III | Arcuate ligament, fabellofibular ligament, capsule, LCL |
The order of insertion of structures on the proximal fibula is, from anterior to posterior, the LCL, the popliteofibular ligament, and the biceps femoris.
Crescent-shaped, fibrocartilagenous structures
Composed predominantly of type 1 collagen
Only the peripheral 20% to 30% of the medial meniscus and the peripheral 10% to 25% of the lateral meniscus are vascularized (medial and lateral genicular arteries, respectively; see Figure 4-1).
Medial meniscus is more C-shaped; lateral meniscus is more circular (see Figure 4-1).
The two menisci are connected anteriorly by the transverse (intermeniscal) ligament.
Articulation between the patella and femoral trochlea
Patella has variably sized medial and lateral facets.
Articular surface of the patella is the thickest in the body.
The patella can withstand forces several times those of body weight.
The medial patellofemoral ligament is present in the second medial layer (Figure 4-4).
1. Ligamentous biomechanics: The role of the ligaments of the knee is to provide passive restraints against abnormal motion (Table 4-3).
Table 4-3
Biomechanics of Knee Ligaments
| Ligament | Restraint |
| ACL | Minimizing anterior translation of the tibia in relation to the femur (85%) |
| PCL | Minimizing posterior tibial displacement (95%) |
| MCL | Minimizing valgus angulation |
| LCL | Minimizing varus angulation |
| MCL and LCL | Acting in concert with posterior structures to control axial rotation of the tibia on the femur |
| PCL and posterolateral corner | Acting synergistically to resist posterior translation and posterolateral rotary instability |
2. Structural properties of ligaments: The tensile strength of a ligament, or maximal stress that a ligament can sustain before failure, has been characterized for all knee ligaments. However, it is important to consider age, ligament orientation, preparation of the specimen, and other factors before determining which graft to use.
ACL: approximately 2200 N and up to 2500 N in young individuals
The tensile strength of a 10-mm patellar tendon graft (young specimen) is more than 2900 N and is about 30% stronger when it is rotated 90 degrees. However, this strength quickly diminishes in vivo.
PCL: approximately 2500 to 3000 N, but this has been disputed
3. Kinematics: The motion of the knee joint and interplay of ligaments have been described as a four-bar cruciate linkage system (Figure 4-5).
As the knee flexes, the center of joint rotation (intersection of the cruciate ligaments) moves posteriorly, causing rolling and gliding at the articulating surfaces.
The collagen fibers of the menisci are arranged radially and longitudinally (Figure 4-6).
Studies have shown that an ACL deficiency may result in abnormal meniscal strain, particularly in the posterior horn of the medial meniscus (Figure 4-7).
1. Complete history of the injury
2. Clarification of mechanism of injury
4. Important key historical points (Table 4-4)
Table 4-4
Key Historical Points That Indicate Mechanism of Injury
| History | Significance |
| Pain after sitting or climbing stairs | Patellofemoral cause |
| Locking or pain with squatting | Meniscal tear |
| Noncontact injury with “popping” sound/sensation | ACL tear, patellar dislocation |
| Contact injury with “popping” sound | Collateral ligament tear, meniscal tear, fracture |
| Acute swelling | ACL tear, peripheral meniscal tear, osteochondral fracture, capsule tear |
| Knee “gives way” | Ligamentous laxity, patellar instability |
| Anterior force: dorsiflexed foot | Patellar injury |
| Anterior force: plantar-flexed foot | PCL injury |
| Dashboard injury | PCL or patellar injury |
| Hyperextension, varus angulation, and tibial external rotation | Posterolateral corner injury |
ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.
1. Key examination points are shown in Table 4-5.
Table 4-5
Most common causes of an acute hemarthrosis: ACL tear (70%), patella dislocation, osteochondral fracture, and isolated meniscal tear
2. Examination performed with the patient under anesthesia may be helpful in some cases.
C Instrumented measurement of knee laxity
1. KT-1000 and KT-2000 Knee Ligament Arthrometers (MEDmetric, San Diego, California) are the devices most commonly used for standardized laxity measurement.
Weight-bearing 45-degree posteroanterior view
Merchant or Laurin view of the patella
Several findings and their significance are listed in Table 4-6.
Table 4-6
Knee Injuries: Radiographic Findings
| View/Sign | Findings | Significance |
| Lateral-high patella | Patella alta | Patellofemoral pathologic process |
| Congruence angle | µ = −6 degrees; SD = 11 degrees | Patellofemoral pathologic process |
| Tooth sign | Irregular anterior patella | Patellofemoral chondrosis |
| Varus/valgus stress view | Opening | Collateral ligament injury; Salter-Harris fracture |
| Lateral capsule (Segond) sign | Small tibial avulsion off lateral tibia | ACL tear |
| Pellegrini-Stieda lesion | Avulsion of medial femoral condyle | Chronic MCL injury |
| Lateral-stress view: stress to anterior tibia with knee flexed 70 degrees | Asymmetric posterior tibial displacement | PCL injury |
| Weight-bearing posteroanterior view flexion | Early DJD, OCD, notch evaluation | |
| Fairbank changes | Square condyle, peak eminences, ridging, narrowing | Early DJD (postmeniscectomy) |
| Square lateral condyle | Thickened joint space | Discoid meniscus |
Normal bony anatomy is demonstrated in Figure 4-8, A. Many of these findings are illustrated in Figure 4-8, B.
Evaluation of patella height is accomplished by one of three commonly used methods (see Figure 4-8, C).
2. Stress radiographs: These are useful for evaluating injuries to the femoral physis (to differentiate from MCL injury) and are becoming the “gold standard” in diagnosing and quantifying PCL injury. They can also be used to evaluate LCL and PLC injuries.
3. Nuclear imaging: Technetium-99m bone scans are useful in diagnosing stress fractures, early degenerative joint disease, and complex regional pain syndrome.
4. Magnetic resonance imaging (MRI): This has become the imaging modality of choice for diagnosis of ligament injuries, meniscal disease, avascular necrosis, spontaneous osteonecrosis of the knee, and articular cartilage defects and has replaced the use of arthrography. On coronal MRI sequences, meniscal root tears are seen as a band of low-signal fibrocartilage. Occult fractures of the knee can be identified by a double fluid-fluid layer, which signifies lipohemarthrosis.
5. Magnetic resonance arthrography: Intraarticular magnetic resonance arthrography is the most accurate imaging method for confirming the diagnosis of repeated meniscal tears after repair.
6. Computed tomography (CT): CT has been replaced largely by MRI, but it is still useful in the evaluation of bony tumors, patellar tilt, and fractures. CT has been advocated as a tool to assist in operative planning for patellar realignment by allowing measurement of the tibial tuberosity–trochlear groove (TT-TG) distance; authors recommend distal realignment procedures for a TT-TG distance exceeding 20 mm. MRI can also be used to measure TT-TG distance.
7. Arthrography: This technique was useful historically for the diagnosis of MCL tears and has been supplanted by MRI. However, it can be useful when MRI is not available or tolerated by the patient, and it can be combined with CT.
8. Tomography: Tomograms are preferred to CT in the evaluation of tibial plateau fractures at some medical centers.
9. Ultrasonography: This technique is useful for detecting soft tissue lesions about the knee, including patellar tendinitis, hematomas, and extensor mechanism ruptures, in some centers. Ultrasonography has begun to be used to evaluate meniscal tears but is not as sensitive as MRI.
See Supplemental Images on expertconsult.com.
1. The “gold standard” for the diagnosis of knee disease
2. The benefits of arthroscopic over open techniques include smaller incisions, less morbidity, improved visualization, and decreased recovery time.
2. Accessory portals, sometimes helpful for visualizing the posterior horns of the menisci and PCL
1. Each knee arthroscopy should include an evaluation of the suprapatellar pouch; patellofemoral joint and tracking; medial and lateral gutters; medial compartment, including the medial meniscus and the articular surface; the lateral compartment, including the lateral meniscus and the articular surface; and the intercondylar notch to visualize the ACL and PCL.
2. The posteromedial corner can be best visualized with a 70-degree arthroscope placed through the notch (modified Gillquist view) or a posteromedial portal.
Meniscal tears are the most common injury to the knee that necessitates surgery.
The medial meniscus is torn approximately three times more often than the lateral meniscus.
There is an increased rate of osteoarthritis in knees after both meniscal tears and meniscectomy.
Traumatic meniscal tears are common in young patients with sports-related injuries.
Degenerative tears usually occur in older patients and can have an insidious onset.
Meniscal tears can be classified according to their location in relation to the vascular supply, their position (anterior, middle, or posterior third), and their appearance and orientation (Figure 4-10).
Meniscal root tears completely disrupt the circumferential fibers of the meniscus and can lead to meniscal extrusion.
The vascular supply of the meniscus is a primary determinant of healing potential.
In the absence of intermittent swelling, catching, locking, or giving way, meniscal tears—particularly those degenerative in nature—may be treated conservatively.
Tears that are not amenable to repair (e.g., peripheral, longitudinal tears)—excluding those that do not necessitate any treatment (e.g., partial-thickness tears, those <5 to 10 mm in length, and those that cannot be displaced >1 to 2 mm)—are best treated by partial meniscectomy.
Should be done for all peripheral longitudinal tears, especially in young patients and in conjunction with an ACL reconstruction
Four techniques are commonly used: open, “outside-in,” “inside-out,” and “all-inside” (Figure 4-12).
The latest generation of “all-inside” devices allows tensioning of the construct.
Regardless of the technique used, it is essential to protect the saphenous nerve branches (anterior to both the semitendinosis and gracilis muscles and posterior to the inferior border of the sartorius muscle) during medial repairs and to protect the peroneal nerve (posterior to the biceps femoris) during lateral repairs (Figure 4-13).
