CHAPTER SYNOPSIS
Osteonecrosis of the hip is a disease with many different etiologies that often leads to femoral head collapse and premature hip arthritis. This disease often occurs in the younger patient; thus appropriate and timely treatment is critical for preservation of the native hip joint. No consensus exists regarding the appropriate treatment for the different stages of osteonecrosis. This chapter reviews the current standards of care as well as some historic and potential future treatment options.
IMPORTANT POINTS
- 1
With core decompression, the stage and site of the lesion influence the outcome. Supplementing the procedure with nonvascular bone graft may improve clinical success by up to 86%. The ideal candidate has Ficat stage I or II lesions that are sclerotic, with less than 30% involvement.
- 2
The free vascularized fibular graft has a complication rate as high as 20%, with better results in precollapse lesions. Ideal candidates are patients younger than 35 years with precollapse lesions and less than 30% head involvement.
- 3
With proximal femoral osteotomies, transtrochanteric osteotomies in North America have given unfavorable results, but intertrochanteric osteotomies show more successful results. Ideal candidates are patients younger than 40 years with precollapse or early postcollapse lesions with no acetabular involvement and a small Kerboul angle.
- 4
Hemi-resurfacing has shown favorable results in early and mid-term follow-up. The ideal candidate is younger than 30 years with no acetabular cartilage involvement.
- 5
Total hip resurfacing has shown quite promising early-to mid-term results. The ideal candidate has less than 50% head involvement. The risk of metal ion exposure must be discussed with women of child-bearing age.
- 6
Bipolar hemiarthroplasty has shown poor results and has limited indications.
- 7
Total hip arthroplasty has shown excellent long-term results. Ideal candidates are patients older than 50 years with acetabular involvement.
CLINICAL/SURGICAL PEARLS AND PITFALLS
- 1
Careful discussion with the patient regarding expectations after hemi-resurfacing is important, especially regarding pain relief, because results often are not comparable to arthroplasty. Reserve these techniques for the patient younger than 40 years with no to minimal cartilage involvement.
- 2
With total hip replacement patients are at high risk of dislocation; thus sparing and repair of the posterior capsule/short external rotators are important. Maximizing femoral head diameter with the use of wear-resistant bearings should be strongly considered.
- 3
With metal-on-metal hip resurfacing, head involvement should be less than 50%. During curing of the cement, copious irrigation of the femoral prosthesis should be done to minimize thermal necrosis. Women of child-bearing age as well as patients with a history of metal hypersensitivity must be carefully counseled about the risk of metal debris exposure.
INTRODUCTION
Osteonecrosis of the hip is a disease with many different etiologies that often leads to femoral head collapse and premature hip arthritis. This disease process generally occurs in the younger patient; therefore appropriate and timely treatment is critical for preservation of the native hip joint. However, the literature on the outcome of the various treatment options for osteonecrosis can be overwhelming, spanning medical treatment to osteotomies and joint replacements with few randomized clinical trials. This was highlighted in the recent report by McGrory et al, who found no real consensus in the treatment of osteonecrosis among members of the American Association of Hip and Knee Surgeons. With the Steinberg staging system and various case presentations, each surgeon was given 11 treatment options for the cases, ranging from nonoperative treatment to total hip arthroplasty (THA). They found that although core decompression and THA were the most common procedures for precollapse and postcollapse, respectively, consensus for these procedures was quite variable in terms of size of lesion and different patient age groups. This chapter reviews current nonsurgical and surgical management techniques of osteonecrosis of the hip.
NONSURGICAL TREATMENT
The use of nonsurgical treatment in osteonecrosis of the hip is uncommon. It generally is reserved for early and precollapse stages of the disease. The concern about nonsurgical treatment is whether it delays or stops the natural progression of the disease process or if it allows a more catastrophic collapse of the head, which may preclude any less invasive surgical procedures. Nonsurgical options include restricted weight bearing as well as the use of pharmacologic agents. Altering the weight-bearing status is used to relieve the necrotic segment of the femoral head, allowing it to heal without progressing to collapse. This mode of treatment has had less than 5% success in the literature. Restricting the weight-bearing status for osteonecrosis of the hip currently is reserved for patients who are unable to undergo surgery or want to delay surgery for a short period and in cases of small, asymptomatic lesions.
One of the more promising fields is the use of pharmacologic agents targeted at the underlying etiology and/or optimization of the repair process. These agents include lipid-lowering drugs, vasodilators, anticoagulants, and bisphosphonates, of which the latter two have shown the most promise. Bisphosphonates function by inhibiting osteoclasts, thereby slowing the bone resorption process to ultimately prevent femoral head collapse. Lai et al performed a randomized, controlled trial of 40 patients with Steinberg stage II or III nontraumatic osteonecrosis of the femoral head with a necrotic area of less than 30%. One group received alendronate 70 mg/week for 25 weeks and the other received a placebo. At 24 months of follow-up, 19 of 25 femoral heads collapsed in the placebo group, whereas only two of 29 collapsed in the alendronate group. Similarly, Argawala et al found that alendronate reduced pain, improved function, and slowed osteonecrosis progression in 100 hips. The use of bisphosphonates shows much promise, but its use is limited to early precollapse stages of the disease and requires further validation of its efficacy.
Other pharmacologic agents that have shown promise are anticoagulants. Many patients with osteonecrosis of the femoral head are widely believed to have thrombophilic-hypofibrinolytic disorders. Therefore some centers have proposed that patients with early precollpase stages of osteonecrosis be treated with anticoagulants such as enoxaparin. Glueck et al treated 35 patients with early precollapse stage of osteonecrosis with enoxaparin; 31 hips did not require surgery and showed little progression from their precollapse stage after 2 years. Although promising, as with other pharmacologic agents further long-term studies are required.
Ideal Candidate
Because research is ongoing in the use of pharmacologic treatments, these are still not considered part of standard care. The hope is that these agents would be most effective in the precollapse stage, with the impact of the lesion size still remaining to be determined.
SURGICAL TREATMENT
Despite the use of various nonsurgical treatment modalities, most patients with osteonecrosis of the hip require some form of surgical intervention. The most critical aspect is determining the appropriate indications of the various surgical procedures, with the symptomatic precollapse lesions having the best chance of avoiding a joint replacement. Surgical treatment of osteonecrosis of the hip can be divided into joint-preserving surgery and joint arthroplasty.
Joint-Preserving Surgery
Joint-preserving surgery is mainly indicated for hips in the early stages of the disease, that is, precollapse and postcollapse with some necrotic lesions ( Fig. 25-1 ). Such procedures include core decompression, vascularized and nonvascularized bone grafting, and proximal femoral osteotomies. These procedures have shown varying degrees of success in the literature as a result of the varying indications based on presence or absence of collapse, size of the osteonecrotic lesion, and surgical technique used.
Core Decompression
The goal of core decompression is to remove a tract of necrotic bone from the femoral head to reduce the intraosseous pressure and promote neovascularization and optimize femoral head blood flow. Core decompression was first performed by Ficat and Arlet, but for more of a diagnostic purpose to obtain histologic samples of the necrotic segment from the femoral head. However, when they also noticed symptomatic improvement of the patients’ hip pain, its use and indications expanded. Since then numerous studies have been published on this procedure with varying results, in part because of the different indications and techniques used. In a prospective, randomized study of 55 hips comparing core decompression with nonsurgical treatment, Stulberg et al concluded that core decompression was more effective for early stages of osteonecrosis. In contrast, Koo et al found no difference between nonsurgical treatment and core decompression. These contrasting findings led several authors to perform systematic literature reviews to determine the efficacy of core decompression. Smith et al looked at 702 hips that underwent core decompression, defining success as no reoperation. A total of 78% of Ficat I, 62% of Ficat II, and 41% of Ficat III hips at an average of 38 months had a successful treatment. Similarly, Mont et al reviewed 42 studies that included 1206 hips treated with core decompression and 819 hips treated nonsurgically. Overall they found a good result in 71% of hips treated with core decompression before collapse and only 35% good results in hips treated with nonoperative measures. Because core decompression is a relatively simple and less invasive procedure, postcollapse lesions also were treated with this technique, but the results were much less predictable. Smith et al found that the success of core decompression dropped to 20% for hips with a crescent sign and 0% in hips with definitive collapse. Fairbank et al showed only a 27% success rate in patients with collapse. In a more detailed analysis, Steinberg concluded that stage and site of lesion clearly influenced the results of core decompression. In his study only 22% of stage I and stage II hips with 15% or less head involvement treated with core decompression and loose cancellous graft required THA compared with 39% and 40% for stage I hips and stage II hips with 15% or more involvement, respectively. Another factor to consider is the appearance of the femoral head lesion—that is, cystic versus sclerotic. Bozic et al reported that in 54 hips treated for osteonecrosis, zero out of seven stage I sclerotic precollpase lesions had evidence of radiographic or clinical failure. In contrast, 13 of 16 stage I cystic lesions showed radiographic and/or clinical failure. This led them to conclude that core decompression has a limited role in cystic precollapse lesions. To improve the results of core decompression, researchers have been combining core decompression with grafting, ranging from bone substitute, to allograft to autogenous allograft, with free vascularized fibular graft representing the most aggressive form.
Nonvascularized bone grafting as an adjunct to core decompression was introduced by Phemister. Since then various techniques have evolved, but the ultimate goal was to provide structural support as well as a scaffold for repair and remodeling of the femoral head during the revascularization process. The core tract procedure involves the removal of an 8- to 10-cm cylindrical core of bone from the femoral head and neck, which is subsequently filled with cortical strut graft. The largest series is that of Smith et al, which had poor clinical results in 71% of patients at 14 years of follow-up. This is in contrast to the results of Buckley et al, who reported satisfactory to excellent results in 18 of 20 patients at a mean follow-up of 8 years. More recently, Lieberman et al, using a combination of morselized allograft and bone morphogenetic protein placed in the core tract, reported an overall clinical success rate of 86% in 17 hips at a mean follow-up of 53 months.
The currently favored technique for core decompression is the percutaneous drilling technique with the use of a 3.2-mm Steinmann pin. This technique involves placing the patient on a fracture table and drilling the lesion under fluoroscopic guidance with the Steinmann pin, starting at a level above the lesser trochanter and ensuring that the pin does not penetrate the articular cartilage of the femoral head. This technique was described by Mont et al and has been shown by Song et al to have a lower rate of collapse (14.3% vs. 45%) compared with the more traditional techniques using a large core tract. Postoperatively the patient should remain partial weight bearing with crutches for at least 6 weeks to prevent fracture. Subtrochanteric fracture, which is a devastating complication, can occur if the entry site of the drill is below the lesser trochanter. Camp et al reported four subtrochanteric fractures in 40 hips after core decompression.
Ideal Candidate
The ideal candidates for core decompression have early Ficat stage I or II lesions that are sclerotic. In terms of size of lesion, the best results are in patients who have less than 30% involvement of the femoral head. Poor outcomes occur in patients with Ficat II cystic lesions and those on long-term steroids. No definitive evidence shows that bony substitutes and/or growth factors significantly improve the clinical outcome of core decompression.
Open Nonvascularized Bone Grafting
To provide a more effective way to remove the necrotic bone before grafting, techniques such as the “light bulb” or “trapdoor” procedures have been developed. The light bulb procedure, developed by Rosenwasser et al, involves making a window in the femoral head-neck junction and filling in the defect in the femoral head with autogenous cancellous bone graft. In a series of 15 hips, they reported that all were asymptomatic at a mean of 12 years. More recently, Mont et al reported an overall clinical success rate of 86% in 21 hips at a mean of 48 months. The trapdoor procedure is yet another variation to the technique of nonvascularized bone grafting. In this procedure the hip joint is exposed and the necrotic segment of the head is identified. Once identified, the edges of the segment are elevated like a trapdoor. The necrotic bone is subsequently removed and replaced with cancellous and/or cortical strut graft. The “trapdoor” is then put back and held in place securely. The results of this technique have been reported to be successful in a majority of patients but are limited to small groups of patients and short-term follow-up.
Ideal Candidate
The ideal candidate for nonvascularized bone grafting of osteonecrotic lesions of the femoral head is similar to that for core decompression: patients with precollapse or early postcollapse lesions with less than 2 mm of head depression. Whether grafting the necrotic lesion could potentially be of benefit for lesions with greater than 30% of head involvement is unclear. In addition, these patients also should have an intact articular surface without acetabular involvement and not be on high-dose or long-term steroids. Patient age has no specific cutoff. Obviously the younger the patient, the more aggressively this technique should be pursued, but most would agree that a patient older than 45 years should strongly be considered for a joint replacement.
Free Vascularized Fibular Grafts
Free vascularized fibular graft was introduced as a means to reconstitute a blood supply to necrotic bone while also providing structural support. The five principles of this technique include (1) decompression of femoral head, (2) removal of necrotic bone, (3) replacement of the necrotic bone with autogenous cancellous bone, (4) support of the subchondral bone with viable strong strut bone, and (5) revascularization and osteogenesis of the femoral head. In general the patient’s fibula is harvested as the source of the graft, with its pedicle being the peroneal vessels. The vascularized fibular graft is then inserted into a core tract through the femoral neck while the pedicle is anastomosed to the ascending branch of the lateral femoral circumflex vessels. Complications of this procedure include femoral neck fracture, subtrochanteric fracture, graft failure, donor site morbidity, and heterotopic ossification. Vail and Urbaniak reported a rate of 2.5% for proximal femur fractures with a 19% overall complication rate, which included donor site pain (1.6%) and nerve injury (15%).
This procedure generally is reserved for small to medium precollapse lesions; some have extended the indications to early postcollapse lesions. Urbaniak et al reported on 103 patients who underwent vascularized fibular grafting and found that 31 patients required conversion to a THA at a mean of 7 years. They also found that a worse outcome occurred in those who had preoperative collapse of the femoral head. Similarly, Urbaniak reviewed 1523 hips in the literature that underwent this procedure between 1979 and 2000. He found that the best results occurred in patients who had no collapse. In these patients success was 91% at 6 months to 22 years of follow-up compared with 85% success if collapse was present. As a result, he concluded that free vascularized fibular grafting be performed on patients younger than 50 years with precollapse lesions. Other centers have reported on this technique with inferior clinical results. Louie et al reported a success rate of 73% of 59 hips followed up for an average of 50 months after treatment with vascularized fibular grafts. These patients were treated consecutively, and 80% of the patients were described as having advanced osteonecrosis (Steinberg stages IV and V). Similarly, Sotereanos et al showed that a patient group treated with free vascularized fibular grafts did better than those with nonvascularized fibular grafting, with 70% of patients having an improved Harris hip score compared with only 34% with a nonvascularized graft. The best results have been with earlier stage lesions, with a survivorship of 89% at 50 months for Ficat stage II compared with 65% for core decompression alone.
The poor survivorship of free vascularized fibula grafts for Ficat stage III osteonecrosis also was reported in a series by Sotereanos et al in which the probability of conversion to a THA was 38% for both Ficat stages III and IV at a mean follow-up of 5.5 years. Louie et al reported a 27% conversion rate to THA at a mean of only 2.6 years for patients with Ficat stage III and early stage IV osteonecrosis.
Ideal Candidate
The authors believe that free vascularized fibular grafting of osteonecrotic lesions should be reserved for patients younger than 35 years with precollapse lesions with less than 30% head involvement.
Proximal Femoral Osteotomies
The principle of proximal femoral osteotomy is to remove the necrotic area from the principal weight-bearing area. Proximal femoral osteotomies can be performed to put the hip in varus or valgus and in the subtrochanteric, intertrochanteric, or transtrochanteric regions. Like most other joint-preserving surgeries performed for osteonecrosis of the femoral head, osteotomies have had variable results. The transtrochanteric rotational osteotomy first reported by Wagner and Zeiler in 1960 involves a double osteotomy with a maximal rotation of 180 degrees. This procedure produced optimal results in patients with minimal osteoarthritic changes and a small Kerboul angle. Sugioka et al had the best results with a 78% success rate in 295 patients at a mean of 11 years. Additional satisfactory results were reported by Masuda et al and Sugano et al in Japan. However, the experience in North America was significantly worse, with failure rates as high as 70% at short-term follow-up. The current consensus is that transtrochanteric rotational osteotomies are unpredictable and technically difficult and should have limited or no use in North America. The more common osteotomy procedures are the varus or valgus intertrochanteric osteotomy, which often is combined with flexion or extension depending on the location of the lesion. Merle D’Aubigne et al were one of the first to report on the outcome of this procedure in 1965, with 79% good to excellent results in patients with Ficat stage II or III at a mean follow-up of 6 years. More recently, Maistrelli et al reported 71% successful clinical results at 2 years postoperatively, with 58% good or excellent results at 8 years and 23% requiring a THA or hip arthrodesis. Similarly, Mont et al reported a 76% good or excellent Harris hip score at a mean of 11.5 years after varus osteotomy. Based on that experience, they recommended that a varus or valgus osteotomy not be performed if a 20-degree arc of disease-free medial or lateral femoral head is not present. One of the disadvantages of proximal osteotomies is the difficulty encountered at the time of conversion to a THA. Benke et al, in their report of 105 THAs performed in patients who had a previous proximal femoral osteotomy, reported a 17% complication rate. These complications included difficulty in hardware removal, broken screws, reaming difficulties, and proximal femur fractures.
Ideal Candidate
Patients who may benefit from a proximal femoral osteotomy are younger than 40 years with a symptomatic late precollapse or early postcollapse lesion and no acetabular involvement. The lesion should be relatively small, with a Kerboul angle of 200 degrees or less, and the patient should not be on long-term steroids. For patients between ages 40 and 45 years a proximal femoral osteotomy can still be performed with the same selection criteria; however, the risk/benefit ratio must be carefully weighed against the excellent results of joint replacement.
Joint Replacement
Joint replacement surgery has been quite successful in the treatment of osteoarthritis of the hip; however, in the treatment of osteonecrosis of the hip the results have been variable. These surgeries include hemi-resurfacing arthroplasty, total resurfacing arthroplasty, hemiarthroplasty, and THA.
Hemi-resurfacing
Hemi-resurfacing arthroplasty was designed to preserve femoral bone stock with a metal femoral component articulating against the native acetabular cartilage. The prime advantage of this procedure is that by being able to preserve femoral bone stock, if the procedure fails it can be easily converted to a primary THA with satisfactory clinical results. Also, because the size of the resurfaced femoral head is matched in diameter to the native acetabulum, this construct is stable. Hemi-resurfacing has shown favorable results in the literature both in the early and mid-term stages. Krackow et al reported 84% good to excellent results in Ficat stage III hips at 3 years. Similarly, Scott et al reported 88% good to excellent results at 37 months. Few series have included long-term follow-up. Hungerford et al followed the study group of Krackow and Scott and found good to excellent results in 91% and 61% at 5 years and 10.5 years, respectively. In another study with longer follow-up, Beaulé et al reported good or excellent results in 79% at 5 years and 62% at 10 years. Mont et al compared the outcome of hemi-resurfacing to conventional THA and found that at a mean follow-up of 7 years for the resurfacing and 8 years for THA, a higher percentage of patients who underwent hemi-resurfacing were involved in sports activity. More recently, negative outcomes have been reported after limited hemi-resurfacing arthroplasty from the unpredictable pain relief. Adili and Trousdale reported that only 62% of patients treated with hemi-resurfacing described improvement in symptoms at 3 years, with 27.6% of the hips requiring conversion to THA. Similarly, Cuckler et al reported failure in 32% of their hemi-resurfacing procedures in 16 patients after a mean of 4.5 years from groin pain, with the end point of these failures being conversion to THA.
If hemi-resurfacing is considered within the realm of joint-preserving procedures because the acetabulum is not resurfaced, thus eliminating the issue of bearing surfaces, it offers a quicker recovery and is simpler to convert to THA compared with free vascularized fibular grafts and proximal femoral osteotomies. In addition, it has shown comparable clinical outcomes in terms of pain control and function relative to other joint-preserving procedures for early postcollapse stages of osteonecrosis. Finally, if a femoral component of total hip resurfacing system initially was used, the surgeon may leave it in situ and simply implant an acetabular component, thus converting the hemi-resurfacing to a total metal-on-metal resurfacing.
Ideal Candidate
The ideal candidate for hemi-resurfacing arthroplasty is the active patient younger than 30 years with an osteonecrotic lesion in the precollapse or early postcollapse stage that is too large for other types of joint-preserving procedures ( Fig. 25-2 ). Radiographically, the Kerboul angle usually is greater than 200 degrees with more than 30% involvement of the femoral head. It also is ideal for the young, active patient with Ficat stage III disease. The native acetabulum of these patients also should have little to no evidence of damage.
Related posts:
The Primary Cemented Femoral Stem
Total Hip Arthroplasty in Developmental Dysplasia of the Hip
Proximal Femur Fracture: The Challenging Primary Total Hip Arthroplasty
The Minimally Invasive Total Hip Arthroplasty with Two Incisions
Component Removal: Tricks of the Trade
Impaction Grafting of the Femur
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