Open Treatment for Hip Cartilage Injuries

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CHAPTER 33 Open Treatment for Hip Cartilage Injuries

Michael K. Shindle, Dean G. Lorich, Robert L. Buly, Bryan T. Kelly

Introduction

Articular cartilage injuries of the hip are one of the most challenging orthopedic injuries to treat, and they have received considerably less attention as compared with other joints. Before the advent of cartilage-sensitive magnetic resonance imaging, hip pain in a young patient was typically diagnosed as early arthritis, and it resulted in progressive generalized joint deterioration (e.g., osteoarthritis, rheumatoid arthritis).

Nonarthritic cartilage injuries in the hip refer to focal chondral defects on either the acetabular or femoral side of the joint. Focal chondral defects on the femoral head are relatively uncommon and may result from shear injury or the axial loading of the head within the socket. Traumatic instability from either a hip dislocation or subluxation, as occurs during high-energy contact sports or motor vehicle accidents, may result in these types of focal chondral injuries. Another mechanism of injury includes a lateral impact injury in which there is loading at the greater trochanter in association with a high-energy activity. The subcutaneous location of the greater trochanter limits its ability to absorb large forces. Thus, an impact on this area can transfer a significant amount of energy and load to the hip joint surfaces, thereby resulting in chondral lesions of the femoral head or acetabulum without associated osseous injury. In addition to trauma, other mechanisms that can cause focal chondral lesions of the femoral head include osteonecrosis, underlying bony deformity, and dysplastic conditions.

In a patient with osteonecrosis, the articular cartilage injury of the femoral head is a result of the loss of structural integrity of the subchondral bone. The degree of chondral pathology depends on the extent of the collapse of the underlying subchondral bone. The spectrum of cartilaginous lesions associated with osteonecrosis is wide and may range from mild chondromalacia to severe chondral fractures with complete collapse.

Anatomic abnormalities such as congenital hip disease (e.g., Legg-Calvé-Perthes disease, dysplasia) or slipped capital femoral epiphysis can lead to cartilage lesions of the femoral head. Acute chondrolysis may occur after slipped capital femoral epiphysis, and narrowing of the joint space may occur as early as 1 year after the acute slip injury.

The grade and character of the cartilage lesions depend on the mechanism of injury and the stage at which the lesion is detected. Lesions can be classified as shear injuries, delamination, fissuring, chondral flaps, fractures, and punch or impaction injuries. As these lesions progress to an advanced-stage degenerative condition, they often lose their specific characteristics.

Cartilage injuries on the acetabulum are more common and typically present as localized cartilage delamination defects in the anterosuperior weight-bearing zone of the acetabular rim. The cause of these defects is most commonly femoroacetabular impingement, which will be discussed in chapter 28.

Basic science

The normal thickness of articular cartilage ranges from 2 mm to 5 mm, and it is determined by the contact pressures that occur across a joint. The articular cartilage of the femoral head is thickest on the central and medial surfaces, which corresponds with the loading pattern of the hip joint. The majority of the femoral head chondral surface is involved in load transfer across the joint, which makes the area particularly vulnerable to injury.

Even with minor trauma, cartilage injury may occur, and chondrocyte death has been reported to occur at 20% to 30% of strain of the articular cartilage specimens. Injured cartilage that loses it congruity by fragmentation, indentation, or a crush injury results in a loss of joint function and progressive joint deterioration. Animal models suggest that large, full-thickness osteochondral defects will undergo degenerative changes around the rim of the defect, which can progress to global joint degradation in as little as 1 year. Finite-element models of osteochondral damage have also predicted a similar progression, because compressive strains reach maximum values around the rim of a defect, and the compressive strain values increase concomitantly as the defects become larger.

Indications

Patients with continued pain despite conservative treatment (e.g., activity modification, weight reduction, physical therapy, bracing, medications), who have imaging that is consistent with cartilage defects, and who demonstrate a positive response to an intra-articular injection are candidates for surgical intervention. Larger cartilage defects may be amenable to cartilage resurfacing procedures such as autogenous osteochondral transfer or fresh or fresh-frozen allograft femoral head transplants.

Conventional joint replacements have a long history of restoring function and relieving pain among patients with arthritis. However, primary total hip arthroplasty procedures have high rates of failure in young (i.e., less than 40 years old) and early–middle-aged (i.e., 40 to 60 years old) patients. To preserve bone stock, partial resurfacing procedures that require a minimum amount of bone removal have been developed. Devices have been developed that only require the removal of the affected area of cartilage in an attempt to maintain the natural radius of the curvature of the femoral head.

Brief history and physical examination

In the young patient, hip pain is often characterized by nonspecific symptoms, vague clinical findings, and normal radiographs. Common causes of groin and hip pain among young patients include hip flexor tendonitis, adductor muscle pathology, osteitis pubis, and trochanteric bursitis. However, the goal of the history and physical examination is to narrow down the differential diagnosis to intra-articular pain, extra-articular pain, or central pubic pain associated with athletic pubalgia. The intra-articular nonarthritic pathology of the hip joint includes disorders of the labrum, the iliofemoral ligament, the ligamentum teres, and the chondral surfaces of the femoral head and the acetabulum.

Patients with an intra-articular cause of hip pain may present with pain in the anterior groin, the anterior thigh, the greater trochanter, the buttock, or the medial knee. Other symptoms may include catching, clicking, locking, giving way, or restricted range of motion. Symptoms may be insidious in onset, or they may be preceded by a traumatic event.

Physical examination should include an assessment of the patient’s gait and posture as well as of his or her pelvic obliquity, limb-length inequality, muscle contractures, and scoliosis. The examination of the hip begins with the palpation of specific regions, but, if the pain is truly intra-articular, palpation does not typically cause pain. The active and passive range of motion of both hips should be performed with the patient in both the seated and supine positions. Mechanical symptoms that result from intra-articular pathology can be elicited by applying an axial load while performing an internal rotation of the hip or by having the patient perform a resisted leg raise while in the supine position.

Imaging and diagnostic studies

The initial workup of a patient with a suspected hip injury should include a standing anteroposterior view of the pelvis, a cross-table lateral view, and false-profile views of both hips. The main purpose of radiographs is to evaluate for the presence of femoroacetabular impingement, joint space narrowing, or acetabular dysplasia. A variety of normal radiographic indices have been described to differentiate normal from abnormal bony anatomy and include the center-edge angle, the Tönnis angle, the neck-shaft angle, the anterior offset, and the crossover sign.

With appropriate pulse sequencing, magnetic resonance imaging has become the examination of choice for the evaluation of unexplained hip pain and for noninvasively evaluating articular cartilage. Some authors have advocated the use of magnetic resonance arthrography to improve the contrast between the cartilage and the synovial fluid; however, this technique converts magnetic resonance imaging into a more invasive procedure. Noncontrast imaging with an optimized protocol can identify labral and chondral abnormalities noninvasively. At our institution, a screening examination of the whole pelvis is performed with use of coronal inversion recovery and axial proton density sequences. Detailed hip imaging is obtained with the use of a surface coil over the hip joint, with high-resolution cartilage-sensitive images acquired in three planes (sagittal, coronal, and oblique axial) with the use of fast-spin-echo pulse sequences and an intermediate echo time.

Intra-articular injections are a reliable indicator of intra-articular problems in the hip joint and should be used as an adjunct to the diagnostic workup. Significant pain relief after an intra-articular injection provides strong evidence that the patient will respond favorably to the surgical management of focal chondral lesions.

Surgical technique

Larger cartilage defects may be amenable to cartilage resurfacing procedures such as autogenous osteochondral transfer or fresh-frozen allograft femoral head transplants. Fresh osteochondral allograft has been shown to be a successful procedure for other weight-bearing joints in both acute and nonacute settings. The success of the allograft depends on the viability of the articular cartilage and the stability of the graft–bone–host bone interface. When placed into an optimal biomechanical environment and prepared properly, the allograft can successfully incorporate into native bone and cartilage. By contrast, the use of frozen grafts may not be as optimal, because the freezing process has been shown to kill chondrocytes and to limit graft survival. The possible risks of disease transmission and graft availability are issues that are relevant to the use of this treatment strategy. An open surgical dislocation is necessary to match allograft tissue with the patient’s joint surface.

Osteochondral Autograft Transfer

Osteochondral autograft transfer is a cartilage repair technique in which an osteochondral plug is transferred from an area of less contact pressure to the full-thickness focal chondral defect. There has been limited experience with autologous osteochondral transplantation in the hip, but early results have been encouraging. The donor site for this procedure can be the ipsilateral knee or the non–weight-bearing portion of the femoral head–neck junction.

With the use of an osteochondral autograft transfer system (OATS, Arthrex, Inc., Naples, FL), a guidewire is drilled perpendicular to the central portion of the cartilage defect of the femoral head after a surgical hip dislocation has been performed as described by Ganz and colleagues (Figure 33-1). Next, an appropriately sized flat acorn reamer is carried down to the subchondral bone over the guidewire. A recipient punch guide with a diameter that is large enough to encompass the chondral defect in its entirety is selected and tapped down to the subchondral surface of the femoral head. The depth of the osteochondral plug is then measured.

Figure 33–1 A focal chondral defect of the femoral head after a surgical hip dislocation has been performed.

The donor site should be harvested from an area of less contact pressure. At our institution, for the treatment of focal chondral injuries of the femoral head, we have used the ipsilateral knee (i.e., the superolateral aspect of the lateral femoral condyle) as the donor site. With the use of a donor punch guide of the same diameter, the guide is malleted down to the same depth as the recipient plug, and the plug is removed. The donor osteochondral plug can be press fit into the recipient site and lightly impacted with a mallet until it is continuous with the surrounding articular cartilage of the femoral head (Figure 33-2). Multiple plugs may be necessary, depending on the size of the chondral defect (Figure 33-3).

Figure 33–2 A demonstration of the osteochondral autograft transfer system procedure with a single cylindrical core graft of articular cartilage and subchondral bone taken from non–weight-bearing regions of the knee (i.e., the donor site) and transplanted into the prepared holes within the defect (i.e., the recipient site).

Figure 33–3 A demonstration of the osteochondral autograft transfer system procedure, with multiple cylindrical grafts in place.

Arthrosurface HemiCAP

The Arthrosurface HemiCAP (Arthrosurface, Inc., Franklin, MA) was designed to treat articular surface defects with an implant that can match the surface and contour of the femoral head (Figure 33-4). The device consists of a titanium fixation screw and a cap-like implant made from a cobalt chrome alloy with a central post on its underside. A surgical hip dislocation is performed as previously described by Ganz and colleagues. The diameter of the defect is measured, and a guidewire is introduced into the middle of the defect (Figure 33-5). The fixation component is used as a central axis, and reamers are then used to map the contours of the patient’s articular cartilage defect (Figure 33-6, A and B). After the surface is prepared, the articular cap implant is seated into position (Figure 33-7, A and B).

Figure 33–4 The different articular surface caps that are available.

Figure 33–5 A focal chondral defect of the femoral head has been identified and marked.

Figures 33–6 A and B, Reamers are used to precontour the articular surface to accept the articular cap.

Figures 33–7 A, The final positioning of the arthrosurface articular component adjacent to the surrounding articular cartilage. B, Postoperative plain films that demonstrate the adequate positioning of the implant.

Postoperative rehabilitation

As a general guideline, postoperative rehabilitation after a surgical dislocation of the hip for a partial resurfacing procedure or a chondral transplant is much lengthier as compared with an arthroscopic hip procedure. Patients are usually hospitalized for 5 to 7 days, and they do not bear weight for 12 weeks to avoid the nonunion of the trochanteric flip osteotomy site. Isometric quadriceps contractions and early hip motion are encouraged. A return to full activity usually occurs between 6 and 12 months postoperatively.

Technical Pearls

• During the surgical dislocation, meticulous dissection in combination with excellent hemostasis will decrease the incidence of heterotopic ossification. For the OATS procedure, careful surgical planning from the donor site is necessary for the more accurate recreation of the femoral head geometry. The use of precise OATS instrumentation is required.

• During the arthrosurface procedure, the center of the osteochondral lesion has to be precisely identified. The guide pin has to be inserted into the center of the osteochondral defect perfectly perpendicular to the defect; when drilling occurs, this will allow for the best restoration of the articular geometry. In addition, during the tapping portion of the procedure, sclerotic bone is commonly encountered, which may cause instrument breakage. After the screw is inserted, precise measurements need to be taken in four quadrants to allow for accurate implant selection. The largest standard-diameter prosthesis is 35 mm, so careful planning is necessary to determine whether a larger custom prosthesis is necessary.

Results and outcomes

Siguier and colleagues reported about their results with the use of the MS prosthesis (Tornier, Saint-Ismier, France) for osteonecrosis of the femoral head. Thirty-seven procedures were performed, and there was an average follow up time of 49 months. The average age of the patients was 43 years, and the preoperative Ficat classification was stage III in 26 hips, stage IV in 10 hips, and stage II in 1 hip. There were nine failed procedures that were related to the extension of the osteonecrosis. Of the 28 surviving implants, 24 patients had excellent or good hip scores according to the Merle d’Aubigné system.

Complications

Although these treatments have been used clinically for more than 5 years, there is a notable absence of comparative studies and long-term outcome information. Siguier and colleagues reported about 37 partial surface replacements for osteonecrosis; there were nine failures that were mainly attributable to the extension of the osteonecrosis. The failures were treated with total hip arthroplasty. However, there were no immediate postoperative general or surgical complications.

Both procedures have complications related to the surgical hip dislocation, including the nonunion of the osteotomy site, heterotopic ossification between the gluteus minimus and the capsule, and blood clots. During the OATS procedure, complications may include a lack of incorporation of the osteochondral plugs, difficulty with restoring the normal congruity of the femoral head, and donor site pain from the superolateral aspect of the knee.

During the arthrosurface procedure, complications may include the inability to reestablish the normal congruence of the femoral head, persistent pain caused by cartilage degeneration along the acetabular side as a result of metallic irritation, the progressive collapse in the presence of osteonecrosis, and the progressive degeneration of the surrounding cartilage that leads to osteoarthritis.

Conclusions

As a result of increased awareness and the advent of magnetic resonance imaging cartilage-sensitive pulse sequences, focal chondral injuries of the hip are becoming increasingly recognized as occult sources of hip pain that may be amenable to a variety of different surgical interventions. Focal chondral lesions of the femoral head are usually caused by direct traumatic events, whereas cartilage delamination injuries on the acetabular rim are more commonly caused by femoroacetabular impingement. Appropriate management depends on the location and size of the lesion as well as a number of patient factors, including symptoms, age, activity level, and the patient’s ability to comply with postoperative rehabilitation.

The OATS and arthrosurface techniques that are discussed in this chapter are relatively new and continue to evolve. In the short term, patients have symptomatic improvement, but long-term follow up is necessary. As we develop a better understanding of the relevant disease processes, biologic solutions should be implemented in an attempt to alter the natural progression of cartilage degeneration.

Annotated references

Byrd J.W. Lateral impact injury. A source of occult hip pathology. Clin Sports Med.. 2001;20:801-815.

This article describes a lateral impact injury that results in an isolated traumatic chondral injury that can occur as a result of impact loading over the greater trochanter. Arthroscopy can be a valuable tool for both the assessment and management of chondral injuries..

Byrd J.W., Jones K.S. Diagnostic accuracy of clinical assessment, magnetic resonance imaging, magnetic resonance arthrography, and intra-articular injection in hip arthroscopy patients. Am J Sports Med.. 2004;32:1668-1672.

This retrospective review of 40 patients with hip pain included clinical assessment, high-resolution magnetic resonance imaging, magnetic resonance arthrography with gadolinium, intra-articular bupivacaine injection, and arthroscopy. The parameters were assessed for reliability with the use of arthroscopy for the definitive diagnosis. Response to an intra-articular injection of anesthetic was a 90%-reliable indicator of an intra-articular abnormality..

Ganze R., Gill T.J., Gautier E., et al. Surgical dislocation of the adult hip: a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg.. 2001;83B:1119-1124.

The surgical treatment of femoroacetabular impingement focuses on improving clearance for hip motion and alleviating femoral abutment against the acetabular rim. This article describes the principles of a surgical dislocation of the hip..

Gardner M.J., Suk M., Pearle A., Buly R.L., Helfet D.L., Lorich D.G. Surgical dislocation of the hip for fractures of the femoral head. J Orthop Trauma. 2005;19:334-342.

This article describes a surgical dislocation of the hip to provide superior visualization and fracture stabilization for the treatment of a femoral head fracture..

Lavigne M., Parvizi J., Beck M., Siebenrock K.A., Ganz R., Leunig M. Anterior femoroacetabular impingement: part I. Techniques of joint preserving surgery. Clin Orthop Relat Res.. 2004;418:61-66.

This article reviews open surgical treatment options for cam and pincer impingement..

Shindle M.K., Foo L.F., Kelly B.T., et al. Magnetic resonance imaging of cartilage in the athlete: current techniques and spectrum of disease. J Bone Joint Surg Am.. 2006;88:27-46.

This article reviews the basic science of articular cartilage and reviews different pulse sequences and terminology related to cartilage-sensitive magnetic resonance imaging..

Shindle M.K., Ranawat A.S., Kelly B.T. Diagnosis and management of traumatic and atraumatic hip instability in the athletic patient. Clin Sports Med.. 2006;25:309-326.

Hip instability can be considered either traumatic or atraumatic in nature. The spectrum of hip instability ranges from subluxation to dislocation with or without concomitant injuries. This review article discusses the treatment algorithm for traumatic instability..

Siguier M., Judet T., Siguier T., Charnley G., Brumpt B., Yugue I. Preliminary results of partial surface replacement of the femoral head in osteonecrosis. J Arthroplasty. 1999;14:45-51.

This study reported the initial results of the use of partial surface replacement for osteonecrosis of the femoral head. Twenty-five patients with prostheses were followed for a mean of 43 months. Overall, 78.9% of patients who retained the component had excellent or good hip scores according to the Merle d’Aubigné system, and there were six failures that led to total hip arthroplasty..

Siguier T., Siguier M., Judet T., Charnley G., Brumpt B. Partial resurfacing arthroplasty of the femoral head in avascular necrosis. Methods, indications, and results. CORR. 2001;386:85-92.

This study reports about the results of the use of a partial surface replacement for the treatment of osteonecrosis of the femoral head. Thirty-seven patients were followed for a mean of 49 months. Overall, 85.7% of patients who retained the component had excellent or good hip scores according to the Merle d’Aubigné system, and there were nine failures that led to total hip arthroplasty..

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