Limited Open Osteochondroplasty for the Treatment of Anterior Femoroacetabular Impingement

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CHAPTER 29 Limited Open Osteochondroplasty for the Treatment of Anterior Femoroacetabular Impingement

Murat Pekmezci, John C. Clohisy

Introduction

An abnormal relationship of the femur and the acetabulum that is characterized by repetitive abutment of the anterolateral femoral head–neck junction against the acetabular rim–labral complex is called the femoroacetabular impingement syndrome (FAI). Repetitive anterolateral impingement produces acetabular articular cartilage delamination, labral disease, and, eventually, osteoarthritis. To date, there is no prospective data that shows the natural history of untreated hip impingement. However, there are several retrospective case series that analyzed the structural anatomy associated with hip arthritis. These series demonstrated that deformity at the head–neck junction is commonly associated with osteoarthritis and that this may have a causative role in the disease pathogenesis. Currently, many investigators believe that untreated FAI has a poor prognosis and that the joint pathomechanics will lead to labral tears, articular cartilage injury, and progressive joint degeneration.

Pathophysiology

An appropriate relationship between the femoral head–neck junction and the acetabulum is a prerequisite for normal hip function. Normal hip range of motion requires a specific orientation of the acetabulum as well as of the proximal femur. The wide range of motion of normal hip function requires the appropriate orientation of the proximal femur and the acetabulum as well as normal femoral head–neck anatomy. Any deviation from this optimal orientation and alignment of the acetabulum and the femur may result in a decreased range of motion. For example, a decreased head–neck offset (i.e., the distance between the most prominent part of the anterior femoral neck and the articular surface of the anterior femoral head at the widest diameter of the head) results in less clearance between the neck and the bony acetabulum. As a result, the impingement of the femoral neck against the acetabulum and the labrum may occur within the normal range of hip motion. Activities that involve deep hip flexion (e.g., squatting, cycling) may aggravate the symptoms.

FAI has two types that depend on the anatomic location of the abnormality. The abnormality may be on the acetabular side (e.g., acetabular retroversion, coxa profunda) and result in abnormal coverage or overcoverage of the femoral head; this is called pincer-type impingement. If the abnormality is on the femoral side in the form of an aspheric head–neck junction or an abnormal head–neck junction with a decreased head–neck offset (e.g., slipped capital femoral epiphysis, Perthes abnormalities, femoral neck malunions), it is called cam-type impingement. The third type of FAI is a combination of the cam and pincer types of impingements. In all scenarios, the impingement of either the femoral neck or the head–neck junction at the edge of the acetabulum results in repetitive trauma to the labrum. This leads to degenerative tears in the labrum and the disruption of the labrochondral junction, which leads to osteoarthritis of the hip. Although the degeneration starts in the anterolateral joint space, it may also affect the posteroinferior joint space as a result of the levering of the femoral head on the anterior edge of the acetabulum caused by anterior impingement.

Indications

• The surgical strategy presented here has been primarily used for the treatment of cam-type deformities.
• Pincer abnormalities may be addressed with arthroscopic techniques or open procedures.
• Ideal surgical candidates have symptomatic anterior FAI, are well conditioned, are less than 50 years old, and have no or mild secondary osteoarthritis.

History and physical examination

The most common clinical presentation is activity-related groin pain in the young to middle-aged athletic individual. Associated lateral and posterior hip pain is also commonly observed. The symptoms are frequently intermittent, and the intensity ranges from mild to severe. High-demand sport activities that involve running, cutting, pivoting, and repetitive hip flexion (e.g., soccer) frequently exacerabate symptoms. Patients also complain of groin discomfort with prolonged sitting. Mechanical symptoms of locking and catching may also be problematic, and these presumably result from labral disease or unstable articular cartilage flaps. A history of hip trauma, childhood hip disease, and previous surgeries and treatments should be determined. These patients are commonly evaluated by multiple physicians and have been treated for tendonitis and synovitis. However, conservative treatment commonly fails as a result of the persistent structural abnormalities of the joint.

The physical examination starts with an observation of the patient’s gait and sitting posture. Patients with FAI may avoid sitting erect in a chair. These patients may also have an antalgic gait, depending on the extent of the disease, and abductor weakness is common. Previous surgical scars are inspected to clarify the nature of previous procedures and to facilitate preoperative planning. A Trendelenburg test is used to assess abductor strength. During physical examination, the most common finding is the limited internal rotation of the hip, particularly with simultaneous hip flexion. The anterior impingement test is performed by passively flexing (90 degrees to 100 degrees), adducting (10 degrees to 20 degrees), and internally rotating (5 degrees to 20 degrees) the hip. This motion elicits the groin pain by moving the proximal anterolateral part of the femoral neck into contact with the rim of the acetabulum. A positive test can be indicative of anterior FAI. The Patrick test is performed by flexing, externally rotating, and abducting the hip by placing the ipsilateral foot on the contralateral knee. A positive test (i.e., the presence of groin pain) suggests the irritability of the hip joint and intra-articular hip disease. Finally, an examination of the lumbar spine and the entire limb is necessary to eliminate other sources of pain.

Imaging and diagnostic studies

Plain radiographs are the traditional imaging modality for this condition. They can include a standing or supine anteroposterior pelvic view, a cross-table lateral view with 15 degrees of internal rotation, and a Dunn view or a frog-leg lateral view. The rotation and tilt of the pelvic x-ray should be assessed by observing the symmetry of the obturator foramens and the distance of the symphysis pubis to the sacrococcygeal joint, respectively. The normal value for the latter is 47 mm in females and 32 mm in males. Acetabular inclination and femoral head coverage should be evaluated to rule out associated hip dysplasia (i.e., structural instability). Acetabular version can also be assessed by looking for the presence of a crossover sign, which indicates acetabular retroversion. In addition, joint space narrowing, subchondral sclerosis, and periarticular cysts should be noted as indicators of secondary articular degeneration. The cross-table lateral view is helpful to evaluate the femoral head–neck junction. The femoral head–neck offset, the head–neck offset ratio, and alpha angle can be measured with the use of this view. These measurements have been shown to demonstrate abnormal femoral head morphology that is observed with cam-type impingement, and they can also be analyzed with the 45-degree and 90-degree Dunn views or the frog-leg lateral radiograph.

The next step in imaging should be magnetic resonance arthrography. This modality is sensitive for detecting intra-articular abnormalities (e.g., labral tears, chondral defects), and it is also helpful for excluding other diagnoses (e.g., osteonecrosis of the femoral head, stress fracture, neoplasm, infection). When evaluating patients with FAI, a computed tomography scan with three-dimensional reconstruction is informative with regard to the osseous deformity. The contour of the femoral head–neck junction and the extent of the femoral-sided disease can be appreciated in detail. The version of the acetabulum and associated osseous anomalies of the acetabular rim can also be defined.

Finally, diagnostic intra-articular hip injections provide valuable information about the presence or absence of intra-articular disease. Patients with intra-articular hip diseases (e.g., labral tears) usually report significant pain relief after injection. Alternatively, patients who do not have any pain relief should be re-evaluated for other causes of extra-articular hip disease (e.g., abdominal wall hernia, trochanteric bursitis, spinal stenosis).

Surgical treatment

The goal of the surgical treatment of FAI is to restore a more normal bony anatomy while addressing the associated soft-tissue problems (e.g., labral tears, acetabular cartilage lesions). The ideal surgical approach should possess the following properties:

• It should allow the surgeon to accurately visualize and evaluate disease characteristics.
• It should allow the surgeon to accurately reconstruct the structural hip anatomy.
• It should allow the surgeon to accurately treat the associated labral or acetabular cartilage disease.
• It should cause minimal morbidity while achieving these goals.

Different surgical approaches have been proposed to reach these goals. Ganz and colleagues popularized surgical dislocation and showed that this technique allowed for the 360-degree evaluation of the femoral head with complete access to the acetabulum. They did not observe any evidence of avascular necrosis after 2 to 7 years of follow up. Murphy and colleagues reported about 23 patients who were treated with open osteochondroplasty; 15 patients did not require further surgery, whereas 1 patient required hip arthroscopy to address a torn labrum. Seven patients were later converted to total hip arthroplasty. Spencer and colleagues reported about 19 patients who had osteochondroplasty or intertrochanteric osteotomy via surgical dislocation, and they concluded that this approach is safe and efficacious for treating FAI. Inferior clinical outcomes were observed among patients who had articular cartilage degeneration. Peters and Erickson reported about 20 patients with a minimum of 2 years of follow up. The authors noted severe acetabular cartilage lesions that were not appreciated on preoperative radiographs or magnetic resonance arthrography in 18 hips. Eight hips demonstrated a progression of arthritis, 3 hips were later converted to total hip arthroplasty, and 1 patient was considering total hip arthroplasty. The authors concluded that the prognosis of FAI largely depends on the status of the acetabular cartilage. Finally, Beck and colleagues reported excellent outcome among 13 out of 19 patients who had an open osteochondroplasty procedure after an average of 4.7 years. In summary, surgical dislocation of the hip seems to be an effective procedure for the treatment of FAI, and it is associated with clinical improvement for most patients.

To avoid the potential complications of surgical dislocation, Pierannunzii and d’Imporzano reported a modified anterior approach without surgical dislocation to address FAI. The authors proposed that this approach is advantageous because there is no risk of interference with the posterior blood supply. In addition, the approach provides direct exposure of the anterolateral head–neck junction. However, this approach relies on imaging for the evaluation of the acetabular cartilage, because it does not allow dislocation of the femoral head. The authors reported about 7 patients; all except 1, who had advanced arthritis, demonstrated significant clinical improvement.

An arthroscopic osteochondroplasty technique was proposed to avoid the potential complications involved with open surgical procedures and to expedite the recovery of the patients. Hip arthroscopy allows the surgeon to evaluate the labral and acetabular lesions with the use of a minimally invasive approach. The impingement can also be evaluated and addressed during the same procedure. However, the learning curve of the arthroscopic osteochondroplasty is steep, and the procedure usually takes longer than an open procedure. In addition, the evaluation of the adequacy of the resection is limited by the technique itself. Guanche and Bare reported about 10 patients who were treated with arthroscopic osteochondroplasty procedures with an average of 16 months of follow up. Eight patients without cartilage lesions did substantially better than the 2 patients who did have associated cartilage lesions.

Preferred Surgical Technique

We prefer the surgical dislocation of the hip for cases that involve nonfocal impingement problems or severe deformities and for most cases that require acetabular rim trimming with labral repair. Specific examples include hips with nonfocal femoral head deformities or circumferential pincer impingement abnormalities. Alternatively, hip arthroscopy with limited open osteochondroplasty is an attractive treatment option for the management of cam-type impingement. Hip arthroscopy is performed first, and the surgeon evaluates and treats the intra-articular problems (e.g., labral tears, chondral flaps). If the surgeon chooses to proceed with osteochondroplasty, it is performed through a limited direct anterior approach. This approach eliminates the risk of interfering with the blood supply of the femoral head as well as the risk of trochanteric nonunion while allowing for the direct visualization of the anterolateral rim and the head–neck junction. The soft-tissue dissection is less than that required for a surgical dislocation, and the procedure does not require a trochanteric osteotomy.

Anesthesia and Positioning of the Patient

We prefer general endotracheal anesthesia with muscle relaxation to help with the distraction of the joint. The patient is positioned supine on a fracture table with a hip arthroscopy traction attachment. The first stage of the operation is a hip arthroscopy to evaluate the severity of the disease and to address labral and articular cartilage lesions. The affected lower extremity and hip are maintained in a neutral position of flexion, extension, slight abduction (i.e., 5 degrees to 10 degrees), and neutral rotation. The contralateral extremity is placed in 40 degrees of abduction and 20 degrees of flexion. With the appropriate amount of countertraction on the contralateral extremity, the hip joint is distracted 8 mm to 10 mm with the use of the fracture table traction. The amount of distraction is monitored by fluoroscopy.

Hip Arthroscopy

We make use of the anterior, anterolateral, and posterolateral portals for arthroscopic surveillance (Figure 29-1). These portals are established with fluoroscopic assistance by placing 4.0-mm, 4.5-mm, and 5.0-mm hip arthroscopy cannulas. The joint is systematically evaluated with 70-degree and 30-degree angled arthroscopes. The articular cartilage of the femoral head, the acetabulum, and the acetabular labrum are inspected. In patients with an anterior FAI complex, degenerative tears of the anterior and acetabular labrum are common. These lesions are frequently associated with the delamination of the adjacent articular cartilage at the transition zone, and they are addressed with the appropriate arthroscopic technique. After the joint is inspected, the final arthroscopic plan is developed.

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Figure 29–1 A, Hip arthroscopy is performed with the patient in the supine position through the anterior, anterolateral, and posterolateral portals. B, A 10-cm longitudinal incision is made just distal to the anterosuperior iliac spine. The anterior incision can also be made 2 cm to 3 cm farther lateral to minimize the risk to the lateral femoral cutaneous nerve.

Limited Open Osteochondroplasty

During the second part of the procedure, the patient remains in the same position. After the traction is released, the central post is removed. An anterior longitudinal incision of 8 cm to 10 cm is made starting just distal and lateral (2 cm to 3 cm) to the anterosuperior iliac spine (see Figure 29-1). The dissection is extended laterally in the subcutaneous tissue to dissect directly onto the fascia of the tensor fascia lata muscle. The fascia is incised, the muscle belly is retracted laterally, and the fascia is retracted medially (Figure 29-2). This medial sleeve of tissue contains the lateral femoral cutaneous nerve, which should be protected by placing the fascial incision lateral to the tensor sartorius interval. The interval between the tensor and the sartorius is then developed, and the origin of the rectus femoris is identified (Figure 29-3). Next, the direct and reflected heads of the rectus femoris are released. The rectus is reflected distally, and the adipose tissue and the iliocapsularis muscle fibers are dissected off of the anterior hip capsule (Figure 29-4). Alternatively, the direct head of the rectus may remain intact and be retracted medially. An “I”-shaped capsulotomy is then performed to provide adequate exposure of the anterolateral head–neck junction (Figure 29-5). Most commonly, an outgrowth of osteochondral tissue is observed along the anterolateral head–neck junction (Figure 29-6). The offset from the femoral head to the neck in this region is deficient. The normal head–neck offset anteromedially serves as a reference point for the resection of the abnormal osteochondral lesion. In addition, we almost always observe a marked delineation between the normal articular cartilage of the femoral head and the impinging rim (see Figure 29-6). A ½-inch curved osteotome is used to perform an osteoplasty at the head–neck junction. The osteotome is directed distally and posteriorly to perform a beveled resection to prevent the delamination of the retained femoral head articular cartilage (Figure 29-7). After the osteoplasty is performed and the head–neck offset is re-established, the accuracy of the surgical resection is confirmed with intraoperative fluoroscopy. The Dunn view or the frog-leg lateral view is effective for visualizing the anterolateral head–neck junction and for assessing the reconstruction. The hip can also be examined at this time to assess impingement during hip flexion and during combined flexion and internal rotation; this is performed while palpating the anterior hip to test for residual impingement. If the anterior acetabular rim was overgrown as a result of labral calcification or osteophyte formation, this is carefully debrided until adequate clearance is achieved. Hip motion should improve at least 5 degrees to 15 degrees in flexion and 5 degrees to 20 degrees in internal rotation. The goal of the osteoplasty is to remove all prominent anterolateral osteochondral tissue that contributes to an aspheric shape of the femoral head (Figure 29-8). Bleeding from the surface of the osteoplasty is controlled with bone wax. The joint is irrigated, and the longitudinal and superior transverse arms of the arthrotomy are closed with absorbable sutures. The direct and reflected heads of the rectus tendon, if released, are repaired with nonabsorbable suture, and the remainder of the wound is closed in a standard fashion.

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Figure 29–2 To protect the lateral femoral cutaneous nerve, the tensor fascia lata sheath is incised, and the muscle belly is retracted laterally. The soft-tissue sleeve with the lateral femoral cutaneous nerve is reflected medially.

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Figure 29–3 The rectus femoris tendon, which lies just above the anterior hip capsule, is exposed.

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Figure 29–4 The rectus femoris tendon is released from its insertion into the anteroinferior iliac spine, which exposes the anterior hip capsule. Alternatively, the tendon can be reflected medially without release.

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Figure 29–5 An “I”-shaped arthrotomy is performed, and the femoral head is exposed. A, Anterior hip capsule is shown before and B, after capsulotomy.

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Figure 29–6 A, This limited anterior approach allows the surgeon to evaluate the deformity at the head–neck junction (arrow) and B, acetabulum.

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Figure 29–7 The head–neck junction is reconstructed with the use of direct visualization.

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Figure 29–8 Preoperative AP pelvis A, and frog-leg lateral B, x-rays of a patient with cam-type impingement. The frog-leg lateral view demonstrates the deformity of the head–neck junction (arrow). The postoperative AP pelvis C, and frog-leg lateral D, x-rays demonstrate that all of the bony deformity was removed and that the head–neck offset was re-established (arrow).

Technical Pearls

Labral Debridement or Repair

• Labral repair is considered when the tear is located at the capsular side, where there is increased vascularity and potential for healing.
• It is extremely important to be technically conservative with the partial labral resection.
• Unstable intra-articular flaps of the labrum should be removed.
• The stable capsular labral remnant should be preserved, when possible.
• Full-thickness resection of the labrum should be avoided.

Articular Cartilage

• Articular cartilage delamination along the anterior and superolateral acetabular rim is common.
• Articular flaps should be debrided back to stable articular cartilage.
• Microfracture of acetabular rim disease can be performed for full-thickness defects.

Limited Open Osteochondroplasty

• Wide exposure of the femoral head–neck junction should be obtained to safely and precisely perform the osteochondroplasty.
• Exposure can be enhanced with the release of the rectus tendon, if needed, and an “I”-shaped arthrotomy can be used to enable wide access to the anterolateral head–neck junction.
• A combination of 1/4-inch and 1/2-inch angled and curved osteotomes facilitates the ostoechondroplasty with the use of this surgical approach. A power burr may also be used.
• The dynamic examination of the hip and palpation through the arthrotomy ensures complete decompression of the impinging structures.
• Fluoroscopic examination of the hip after osteochondroplasty assists with the judging of the adequacy of the femoral head–neck junction recontouring.

Postoperative rehabilitation

Patients are observed overnight in the hospital. A pillow is placed under the thigh to maintain hip flexion, thereby decreasing the stresses placed over the rectus repair. Active hip flexion exercises are also prohibited for the first 6 weeks. Abductor strengthening is instituted immediately and continued with a home exercise program. We currently have the patients bear 50% weight during the first 4 weeks, which is followed by gradual weight bearing as tolerated. Nevertheless, it is recommended that these patients avoid contact sports and impact activities (e.g., running) for at least 4 months to minimize the risk of pathologic femoral neck fracture. Enteric-coated aspirin (325 mg) is taken as thromboembolic prophylaxis, and sustained-release indomethacin (75 mg) is used for heterotrophic ossification prophylaxis. Both of these medications are taken for 6 weeks.

Results and outcomes

The results of these procedures are summarized in Table 29-1, but highlights include the following:

• The documentation of clinical outcomes for the surgical treatment of hip impingement disease is limited.
• Early to mid-term results are now available for treament with surgical dislocation of the hip; these results are encouraging for most patients.
• Our experiences with hip arthroscopy and with combined limited open osteochondroplasty have been encouraging. An analysis of our first 36 consecutive cases demonstrated that 29 of the 36 hips had good or excellent clinical results at a mean of 24 months of follow up.

Table 29–1 Results Summary

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Complications

• Neurovascular injury
• Deep venous thrombosis
• Heterotopic ossification
• Femoral neck fracture
• Infection
• Articular cartilage scuffing
• Arthroscopic instrument breakage

Annotated references and suggested readings

Beaule P.E., Allen D.J., Clohisy J.C., Schoenecker P., Leunig M. The young adult with hip impingement: deciding on the optimal intervention. J Bone Joint Surg Am.. 2009;91(1):210-221.

Beck M., Leunig M., Parvizi J., Boutier V., Wyss D., Ganz R. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res. (418); 2004:67-73.

Byrd J.W. Hip arthroscopy. J Am Acad Orthop Surg.. 2006;14(7):433-444.

This article reviews the indications and the hip arthroscopy surgical technique used to treat various intra-articular hip pathologies..

Clohisy J.C., McClure J.T. Treatment of anterior femoroacetabular impingement with combined hip arthroscopy and limited anterior decompression. Iowa Orthop J.. 2005;25:164-171.

This article reviews the general characteristics of FAI. In addition, it provides a detailed description of the limited open osteoplasty technique..

Ganz R., Parvizi J., Beck M., Leunig M., Nötzli H., Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. (417); 2003:112-120.

This article reviews the pathomechanism of the development of osteoarthritis as a result of FAI. The authors propose that surgical treatment may decelerate the development of secondary arthritic changes by alleviating the femoral abutment against the acetabular rim..

Guanche C.A., Bare A.A. Arthroscopic treatment of femoroacetabular impingement. Arthroscopy. 2006;22(1):95-106.

Murphy S., Tannast M., Kim Y.J., et al. Debridement of the adult hip for femoroacetabular impingement: indications and preliminary clinical results. Clin Orthop.. 2004;429:178-181.

Peters C.L., Erickson J.A. Treatment of femoro-acetabular impingement with surgical dislocation and debridement in young adults. J Bone Joint Surg Am.. 2006;88:1735-1741.

Philippon M.J., Maxwell R.B., Johnston T.L., Schenker M., Briggs K.K. Clinical presentation of femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc.. 2007;15(8):1041-1047.

The authors report the common symptoms and physical examination findings of 301 patients who had surgical treatment for the treatment of FAI..

Philippon M.J., Stubbs A.J., Schenker M.L., Maxwell R.B., Ganz R., Leunig M. Arthroscopic management of femoroacetabular impingement: osteoplasty technique and literature review. Am J Sports Med.. 2007;35(9):1571-1580.

This article provides a review of certain aspects of FAI as well as arthroscopic osteoplasty and rim-trimming techniques that are used to address cam- and pincer-type impingement, respectively..

Pierannunzii L., d’Imporzano M. Treatment of femoroacetabular impingement: a modified resection osteoplasty technique through an anterior approach. Orthopedics. 2007;30(2):96-102.

The authors describe a new approach to the treatment of FAI that involves an anterior approach without dislocation of the hip. They report favorable outcomes for 8 patients who had osteochondroplasty with the use of this technique..

Spencer S., Millis M.B., Kim Y.J. Early results of treatment of hip impingement syndrome in slipped capital femoral epiphysis and pistol grip deformity of the femoral head-neck junction using the surgical dislocation technique. J Pediatr Orthop.. 2006;26(3):281-285.

Tannast M., Siebenrock K.A., Anderson S.E. Femoroacetabular impingement: radiographic diagnosis—what the radiologist should know. AJR Am J Roentgenol.. 2007;188(6):1540-1552.

This article reviews the radiographic criteria that are used to diagnose FAI as well as the potential pitfalls of pelvic imaging..

Tanzer M., Noiseux N. Osseous abnormalities and early osteoarthritis: the role of hip impingement. Clin Orthop Relat Res. (429); 2004:170-177.

This article combines the results of three different studies that demonstrated that the anterior femoral head offset deficiency is a common cause of various hip disorders, including labral tears, FAI, and idiopathic hip osteoarthritis..

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