The final outcome of Legg-Calvé-Perthes Disease (LCPD) is variable and depends mostly on the age of the patient at onset and the amount of femoral head involvement. The goals of treatment are to achieve a round femoral head with a congruous hip joint and to contain the femoral head to avoid extrusion.
The final radiographic outcome at maturity was described by Stulberg et al.1 The classification radiographic characteristics are found in patients with LCPD at maturity but before they developed arthritis. It takes into account, among other things, the relationship between the femoral head and the acetabulum. It also correlates with the development of hip osteoarthrosis. Class I is a normal hip joint and developed normal hip ratings. Class II hips presents a spherical femoral head, but with one or more of these: spherical coxa magna, coxa breva, and/or an abnormally steep acetabulum with fair results. Class III is a ovoid femoral head (mushroom shaped) with the abnormalities described for class II. Class IV is a flat femoral head and the abnormalities of head, neck, and acetabulum. Class III and IV had poor outcomes. Class V encompasses a flat femoral head with normal neck and acetabulum (aspherical incongruity). Class V hips had the worst outcomes as most of the heads did not heal completely and led to early osteoarthrosis.
A younger age at onset of the disease correlates with better prognosis. Several studies have demonstrated that when LCPD develops in late childhood or the adolescent years, the results are poor. This is especially true after 10 years of age, at which the outcomes are almost 100% failure with observation.1,2 The age of onset that led to Stulberg class V was around 10 years and developed the worst outcomes.1–4
After an age of 12 years, Joseph et al2 described 3 radiographic femoral head patterns associated with LCPD. The first one is similar to infantile LCPD (late-onset Perthes). Most of these patients will become a Stulberg class III. The second type presents with permanent epiphyseal collapse and more severe symptoms with poor results. The destructive pattern, as expected, had the worst results. This destructive pattern showed little evidence remodeling and was incapacitated long term. In all 3 patterns, there was femoral head enlargement with little or no acetabular growth.
We recommend the term “juvenile osteonecrosis” in this age group because the osteonecrosis course is more similar to adult osteonecrosis than it is to LCPD in younger patients. These juvenile patients are more likely to become Stulberg class V regardless of size of the necrotic segment.1,2 Therefore, the results are mainly affected by the amount of femoral head collapse that exists. However, unlike adults, there may be enough plasticity to allow reconstitution of the necrotic segment at a later stage of involvement. Labral support may also allow the necrotic fragment to become a stable osteochondral defect due to deeper support of the acetabulum to share load on the lateral femoral head. The treatment of this condition is controversial in this older age group. Patients older than the age of 11 years are the focus of this review and treatment proposal.
WHAT MAKES JUVENILE OSTEONECROSIS DIFFERENT FROM PERTHES?
Patients with juvenile osteonecrosis have several different characteristics, which make them unique for treatment. The first is that the femoral head does not undergo the normal revascularization process seen in Perthes. Second, there is little-to-no remodeling of the femoral head or the acetabulum.2,3,5 The other characteristic is that the acetabulum is normal in shape and rarely leads to lateral migration.1 Most of the deformity comes from the collapse and enlargement in size of the femoral head. Therefore, the treatment rationale should be tailored to address these differences.
WHAT SURGICAL TREATMENTS HAVE BEEN ATTEMPTED BEFORE? WHAT HAVE BEEN THEIR RESULTS?
There are reports of various forms of surgical treatment to prevent poor outcomes expected from the natural history studies. However, outcomes from these procedures have been disappointing.
Ippolito et al5 evaluated 13 hips treated by traction and spica casting until radiographic resolution. Nine of the 10 hips followed to maturity-exhibited arthritis. Noonan et al6 and Joseph et al2 have independently reported results of femoral osteotomy for containment in older children. Both of these reports indicate that patients older than 10 years have poor outcomes with varus osteotomy alone.
Shelf acetabuloplasty can produce satisfactory results in younger patients, and does not require joint congruency.4,7–9 Core decompression in the young adult population and late adolescent has shown promising results if performed in the early Ficat stages.9–12 Patients in the precollapsed stages have a better femoral head survivorship (77.6%) than those in the postcollapse stage (27%).
A DIFFERENT WAY TO TACKLE JUVENILE OSTEONECROSIS
We agree with Joseph et al2 that there has to be a different method of the treatment for the juvenile patients. He concluded that the success of any type of treatment will depend on necrotic bone resorption (elimination), new bone formation in its place, and remodeling process that is protected from further deformation by adequate containment.
In contrast to LCPD in younger children, there is an urgency to treat these patients. Several investigators identified that the femoral epiphyseal height is unlikely to improve after collapse. These investigators recommended that surgery should be performed as early as possible to prevent collapse.4,8 If this is a key ingredient to achieve a better outcome, then the treatment should start immediately after the diagnosis. Delays in treatment for observation in this age range are not supported by the literature because the outcomes are almost uniformly poor with observation alone.13
If the natural history of juvenile osteonecrosis is so devastating without treatment, why wait and do nothing? It is our opinion that early core decompression combined with containment in the form of a shelf acetabuloplasty can improve outcomes compared with the natural history and compared with previous treatment methods for this age group. Figures 1–4 will demonstrate a case example.
Two questions will be discussed regarding this opinion:
Why do a Core Decompression?
It is our opinion that the key portion of the procedure is the core decompression. The core and bone grafting will achieve several things. First, it removes the necrotic bone, which has been shown to be a key component of the success of the decompression.11,12 Second, the core allows immediate revascularization from metaphyseal capillaries through the growth plate, which is a barrier to the blood supply of the femoral head in the growing child. Third, in some instances, it may provide some structural support to the collapsing fragment, while enhancing the revascularization process.11 Mont et al11 completed a meta-analysis comparing core decompression with the conservative treatment. Twenty-three percent of those treated nonoperatively had a satisfactory result clinically. Poor results increased with higher Ficat staging.14 Those treated with core decompression fared better with an improved femoral head survival rates.9 Stulberg et al9 also prospectively compared nonoperative management with core decompression. Their results showed that those treated with core decompression had a clinical success of approximately 70% for Ficat stages I to III. Those treated with observation had a clinical success of 20%, 0%, and 10%, respectively for Ficat stages I to III. Patients in stage IV had poor results regardless of treatment. Fairbank et al10 compared Ficat staging and success rates after core decompression. They had better survival rates with core decompression compared with observation in the early stages of necrosis.
Others have performed core decompression followed by grafting with tibia or fibula.12 Their results were poor in 54% of the patients at a mean of 4.5 years. However, they found that patients younger than 30 years of age had better results. They concluded that the most critical portion of the procedure was the removal of the necrotic tissue and packing of bone graft, as the type of strut graft had minimal effect on the procedure. Urbaniak et al15 used vascularized fibular grafting and reported a reoperation rate at a median of 7 years in 30% of their patients. They had a high conversion rate to total hip arthroplasty (more tahn 70% across the border) within 5 years in those with Ficat II or higher.
Why do a Shelf?
Yoo et al8 presented their results of shelf acetabuloplasty in children older than 7 years of age. They found that the best results were in those patients without epiphyseal collapse and reducible head extrusion on attempted abduction without placing increased pressure on the labrum. Two studies have shown that there is remodeling and an increased acetabular depth when a shelf acetabuloplasty is performed.8,16 Daly et al4 reported the results of shelf acetabuloplasty on children older than 8 years. Good results were observed in 22 of 27 hips with a final Stulberg class 1 to 3.
A shelf may be also protective to avoid the development of early arthritis.17,18 Saito et al19 reported that patients that developed arthrosis after LCPD had in average a center-edge angle of 11.6 degrees versus 22.6 degrees in nonarthritic hips. Roush et al20 reported on adult osteonecrosis treated with vascularized fibular graft. The results indicated that those with center-edge angle of ≤25 degrees were 11 times more prone to have progression of collapse and 7 times more prone to require a total joint arthroplasty. Therefore, femoral head coverage with a greater center-edge angle may improve results.
OUR RECOMMENDATION BASED ON THE LITERATURE
First, juvenile osteonecrosis does not fare well after observation or previously reported methods of treatment. Surgery is indicated in these patients based on the natural history studies.1–5
Second, the necrotic tissue should be debrided to allow reconstitution of the femoral head.2,12,21 In addition, bone grafting of the femoral head is warranted. The earlier this is performed in the course of disease, the better the outcomes for preventing femoral head collapse and residual deformity.
Third, the labrum and femoral head should be supported to distribute the forces across the joint and prevent lateral migration. This also provides better acetabular roof and may prevent early degenerative changes.
On the basis of these 3 premises for juvenile osteonecrosis, our recommendation is to perform early core decompression with bone grafting combined with a shelf acetabuloplasty as soon as the diagnosis is made. Parents should be made aware that the natural history has dismal results.
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