Perthes disease refers to self-limiting idiopathic avascular necrosis of capital femoral epiphysis in a child. There is no consensus for the optimum treatment of Perthes disease even 100 years after the first description. The prime aim of the treatment is to maintain the sphericity of the femoral head and the congruency of the femur-acetabulum relationship to prevent secondary degenerative arthritis. Early diagnosis and management can help the collapse of femoral head, progressive femoral head deformity, and impingement.
Key points
- •
The primary goal of the treatment is to prevent irreversible femoral head deformation, incongruent hip, and femoroacetabular impingement.
- •
Preventable treatment strategy is more effective in the early stage (before the stage of advanced fragmentation) than in the late stage of the disease. The timing of the surgery is more important than the type of surgery.
- •
Epiphyseal extrusion is the most important and the only factor that modulates the preventable treatment in early Perthes disease.
- •
Most younger children can be managed conservatively. Surgical containment is essential for children with late-onset Perthes disease. Normal hip joint movements and absence of hinge abduction are the prerequisites for surgical containment.
Introduction
Perthes disease is one of the most common pediatric disorders. It is an aseptic, noninflammatory, self-limiting, idiopathic, avascular necrosis of capital femoral epiphysis in a child. One hundred years after its first description, the exact cause of the Perthes disease is not known. The treatment of Perthes disease may be preventive, remedial, or salvageable in nature depending on when the child is diagnosed.
The aim of treating Perthes disease is to prevent secondary degenerative arthritis of the hip in adult life, which can be achieved by preventing the femoral head from getting deformed if the child is diagnosed early, by minimizing the adverse effects of early deformation of the femoral head if it has already occurred, and by salvaging hips with established deformation of the femoral head.
Introduction
Perthes disease is one of the most common pediatric disorders. It is an aseptic, noninflammatory, self-limiting, idiopathic, avascular necrosis of capital femoral epiphysis in a child. One hundred years after its first description, the exact cause of the Perthes disease is not known. The treatment of Perthes disease may be preventive, remedial, or salvageable in nature depending on when the child is diagnosed.
The aim of treating Perthes disease is to prevent secondary degenerative arthritis of the hip in adult life, which can be achieved by preventing the femoral head from getting deformed if the child is diagnosed early, by minimizing the adverse effects of early deformation of the femoral head if it has already occurred, and by salvaging hips with established deformation of the femoral head.
Natural history
Perthes is a self-limiting disorder as blood supply of the femoral head restores to normal within 2 to 4 years’ duration following initial avascularization. Single or multiple recurrent episodes of interruption of blood supply of the femoral head occur. Once the blood supply to the femoral head is compromised, a series of events occur within and outside the femoral head. Avascular necrosis of part or all of the epiphysis occurs; the necrotic bone is resorbed by osteoclasts. The weakened trabeculae collapse and the epiphysis fragments. Woven bone is laid down on the periphery of the epiphysis and over a period of time this woven bone is replaced by mature lamellar bone and the epiphysis heals completely. Concomitant changes take place outside the femoral head. Hypertrophy of the synovium, ligamentum teres, and the articular cartilage occurs. These soft tissue changes along with muscle spasm initiate femoral head extrusion that tends to increase progressively. The extruded femoral head, when subjected to stresses that pass across the acetabular margin, lead to irreversible deformation of the femoral head. A little remodeling of the femoral head may then occur. Any residual femoral head deformity and joint incongruity will then persist throughout life. Recent evidence has clearly shown that irreversible deformation occurs when the disease has progressed to the late stage of fragmentation or soon after.
Variables that make femoral head deformity worse are femoral head weakening and significant loading. Femoral head weakening correlates with the extent of head involvement. Loading depends on the patient’s activity level, type of activities, and weight. Intervention should necessarily precede the onset of irreversible deformation of the femoral head.
Evaluation of prognostic factors
It is important to know the prognostic factors that affect the final outcome of the disease.
Short-term Prognostic Factors
The factors that determine the shape of the femoral head at the time of healing of the disease include age at onset of the disease, extent of epiphyseal avascularity, extent of epiphyseal collapse, and extent of epiphyseal extrusion. Early onset of the disease, less than 50% of head involvement, less severe collapse, and the absence of epiphyseal extrusion are good indicators of the outcome. Of these factors, epiphyseal extrusion is the most important and the only factor that can be modulated by treatment.
Long-term Prognostic Factors
The factors that predispose to the development of secondary degenerative arthritis include shape of the femoral head at the time of healing of the disease, congruency between the femur and the acetabulum, and age at onset of Perthes disease. Degenerative arthritis of the hip joint is correlated with the irregular shape of the femoral head, incongruent hip, and the late onset of the disease.
Evaluation
Patient Evaluation
The age of onset of symptoms and duration of the disease must be determined. The exact age of onset can guide the planning of the management. Long duration of the disease may cause one to miss the timing for the preventable management strategy. History of passive smoking, which should be evaluated as maternal smoking, at least one smoker living in the child’s household, and wood smoke, are associated with increased risk of Perthes disease.
Clinical Evaluation
The child with Perthes disease limps and complains of occasional pain in the groin, hip, or knee. These symptoms may be present for weeks or even months. The examination shows a mild limp and decreased range of motion in abduction and internal rotation. Occasionally, there may be gross limitation of all range of motion. Persistent hip stiffness is a poor prognostic sign. It is essential to gain normal range of motion of the hip joint before considering containment treatment.
Radiological Evaluation
Plain radiographs (anteroposterior [AP] and frog lateral) are useful to diagnose the stage, the extent, and the severity of involvement of the femoral head. The sequential changes of natural history can be divided into two groups: active disease and healed disease. Disease is considered active when the capital femoral epiphysis looks sclerotic with or without the presence of collapse and reossification. The disease is considered healed when no remnant of avascular bone can be identified on both views. Contrast-enhanced magnetic resonance imaging can clearly define the area of the involvement in the early stage of the disease.
Active stage of disease
Early Stage of the Disease
The femoral head is subjected to deformation in the late stage of fragmentation or soon after this stage, so the active stage of the disease is divided into the early and late stages. The early stage refers to the stage between early avascular necrosis and early stage of fragmentation. The late stage refers to the stage between late fragmentation and early reossification of capital femoral epiphysis.
Management
The age of the child at onset of symptoms, the extent of involvement, stage of the disease, the range of motion of the hip, and the presence of the extrusion of the femoral head must be considered for treatment in the early stage of the disease.
The age of onset can be further divided into less than 5 years, 5 to 8 years, 8 to 12 years, and more than 12 years (adolescent Perthes disease). Adolescent Perthes disease behaves differently from early onset Perthes disease. Nonsurgical treatment is effective and indicated for children who are young (ie, less than 5 years of age).
Containment
Containment refers to repositioning of the anterolateral part of the femoral epiphysis within the confines of the acetabulum to protect the femoral head from being subjected to deforming forces. Containment can be done by casting, bracing, femoral, or innominate osteotomy.
Nonsurgical containment
Abduction cast and brace are commonly prescribed for nonsurgical containment. Various types of orthosis (abduction splint) are available. Rich and Schoenecker recently showed excellent results with an A-frame orthosis with hip range of motion. The disadvantages of the brace are that it requires excellent patient compliance and must be worn for a longer period of time. An abduction orthosis is preferred for children less than 5 years who present with extrusion. Abduction orthosis and cast treatment are tedious and psychologically difficult for the older child (ie, more than 5 years old). The author does not use any brace or splint as a definitive treatment for children older than 5 years of age.
Surgical containment
Surgical methods provide prolonged containment to maintain normal femoral head sphericity during revascularization. The age of onset, the presence of epiphyseal extrusion, the extent of the femur head involvement, and the hip range of motion are key variables to be considered before doing containment.
Children with age of onset less than 8 years have a better prognosis than children with age of onset more than 8 years. The prognosis is very good with the age of onset less than 5 years. Most children do not require surgical containment. The author considers surgical containment only in those children with extrusion during the course of the disease and noncomplaince with the brace.
For children with age of onset between 5 and 8 years, extrusion is the prime factor for deciding surgical containment. A close follow-up is necessary to monitor extrusion in these children. Surgical containment is indicated for children with more than half of the femoral head involved and the presence of extrusion during the course of the disease. For children with less than 50% head involvement without extrusion, nonoperative treatment with non-weight-bearing is preferred. Regular close follow-up of these children is required until the stage of reossification to detect early extrusion.
The natural history of children with the age of onset more than 8 years is not favorable. Surgical containment is more effective than no treatment or brace treatment in older children. Surgical containment is preferred, irrespective of the presence of extrusion, because extrusion is inevitable in these children. The traditional containment treatment cannot be considered for adolescent Perthes disease (age of onset more than 12 years), because the disease behaves entirely differently from the early onset of the disease.
Normal range of motion of the hip joint is a prerequisite for surgical containment. An abduction cast for 6 weeks is preferred before considering surgical containment in children who fail to regain the normal range of motion after a few days of traction.
Type of osteotomy
No consensus exists about the type of surgical containment (femoral and or innominate osteotomy). Proximal femur varus, varus derotation, varus extension, and varus extension derotation are various proximal femoral osteotomies, whereas Salter, triple, and shelf acetabuloplasty are various pelvic osteotomies. There is no consensus on the type of femoral or pelvic osteotomy to be considered. The results are essentially the same with both femoral and pelvic containment. However, normal range of motion of the hip joint and absence of hinge abduction are essential prerequisites for surgical containment.
The authors prefer subtrochantric femur varus derotation osteotomy for surgical containment. Proximal femur osteotomy is performed with 20° varus, open wedge osteotomy, trochanteric epiphyseodesis, and 20° external rotation. No external immobilization is used following surgery. The implant is kept up until complete healing of the disease. There have been no nonunion or hardware failures.
There are several advantages of femur varus osteotomy: it is technically easy to perform; it is as effective as a pelvic osteotomy; and it does not increase intra-articular pressure. The distinct advantage of this osteotomy is that the duration of the disease can be shortened and it can bypass the stage of fragmentation in one-third of children if it is performed in the stage of avascular necrosis ( Fig. 1 ).
There are several disadvantages of femur varus osteotomy, such as trochanteric prominence, persistent abductor lurch, shortening, lack of remodeling of varus, worsening of coxa brevis, and the necessity of second surgery for implant removal. However, open-wedge osteotomy with trochanteric epiphyseodesis has shown minimal shortening and negligible abductor lurch in skeletally mature patients.
The pelvic osteotomy is indicated in older children with total head involvement. There are several advantages of pelvic osteotomy, including absence of shortening of the affected limb and no change in the abductor lever arm. No major second surgery is required for implant removal. However, limitations of the pelvic osteotomy are that there is no evidence to suggest that innominate osteotomy alters the natural healing of the disease and overcoverage with triple osteotomy can be associated with pincer impingement.
The use of a combined salter and proximal femoral varus osteotomies has been described for severe disease in older patients, in children more than 10 years of age with severe subluxation, and in those children where either single femur or innominate osteotomy is insufficient to provide adequate containment.
Trochanteric Epiphyseodesis
Premature fusion of the capital femoral growth plate occurs in a sizable proportion of older children with Perthes disease, which leads to “greater trochanteric overgrowth” and a Trendelenburg gait. Because premature fusion of the femoral capital growth plate cannot be predicted in Perthes, prophylactic trochanteric epiphyseodesis is recommended at the time of containment surgery in children greater than 7 years of age. The author routinely combines trochanteric epiphyseodesis with varus derotation femur osteotomy.
Weight-Bearing Status
The absence of weight-bearing in isolation has proved to be ineffective. Kim and colleagues showed that weight-bearing played a significant role in the development of the femoral head deformity and that less flattening occurred with a non-weight-bearing treatment using a large animal model. However, the optimum duration of non-weight-bearing has not been identified. The author thinks prolonged non-weight-bearing up to the late stage of re-ossification prevents the collapse of the soft bone.
Late Stage of the Disease
Children who present late in the late fragmentation stage or reossification stage often have associated femoral head flattening and extrusion. Hinge abduction is common with femur head flattening and extrusion.
Hinge abduction
Hinge abduction is defined as an impingement of the lateral part of the femoral head on the lateral margin of the acetabulum ( Fig. 2 ). It can be suspected clinically by sudden deterioration of movements of the hip joint (mainly abduction), out-toeing, or in-toeing gait as a compensatory mechanism. AP radiographs typically show widening of medial joint space in abduction. Dynamic arthrogram can add to the diagnosis of reducible or irreducible hinge abduction; it also helps to decide the best congruent position of the hip joint and the diagnosis of anterior and lateral impingement.
Reducible hinge abduction
If the femoral head is centered within the acetabulum without pressing on the lateral margin of the acetabulum, it is considered reducible hinge abduction. Containment surgery can be performed at this stage; however, the anticipated outcome of the surgery is more modest than the anticipated outcome of the early stage surgery. The odds ratio of obtaining a spherical head at healing is 16.8 times less than if surgery is performed early in the course of the disease. Lateral shelf acetabuloplasty can prevent the subluxation of the femoral head and stimulate lateral acetabular growth.
Irreducible hinge abduction
If the femoral head does not center within the acetabulum and the lateral part of the femoral head imposes pressure on the lateral margin of the acetabulum, it is considered irreducible hinge abduction. Various surgeries are described for these noncontainable hips, such as proximal femur valgus osteotomy, articulated hip distraction, shelf and Chiari acetabuloplasty, and femoral head reshaping.
A proximal femur valgus osteotomy is commonly indicated for irreducible hinge abduction to restore joint congruity and to reduce femoroacetabular impingement. It is indicated if the femoral head and acetabulum become congruent when the joint is adducted, but incongruent in a neutral or abducted position. Valgus osteotomy has several advantages: it repositions the abnormal hinge segment away from the acetabulum margin; it increases the weight-bearing surface under acetabulum; it corrects the neck shaft angle; and it increases the abductor muscle length.
The degree of valgus should be decided by the maximum joint congruent position in adduction. Valgus osteotomy may also be combined with additional sagittal components. Valgus extension osteotomy is effective when hinge abduction is combined with flexion deformity of the hip with soft anterior hinge that can be contained within the acetabular socket. When the anterior hump is relatively large and noncontainable, extension combination is not indicated because the hump may cause anterior impingement. The rotation component can also be added with valgus, if the hip shows better congruence in internal or external rotation with adduction. If there is an increased subluxation and the hip remains unstable after a valgus osteotomy, a concomitant acetabular procedure (innominate, shelf, or Chiari osteotomy) is necessary to obtain adequate coverage.
Valgus osteotomy is contraindicated in stiff hips. Articulated hip distraction is useful in children who present late with stiff hips and nonreducible hinge abduction. Articulated hip distraction can be combined with soft tissue release. However, the outcome following valgus osteotomy or articulated hip distraction is modest compared with preventable surgery performed in the earlier stage of the disease.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
