Perthes Containment Surgery (Femoral & Pelvic Osteotomy)

The containment principle. During the necrosis and fragmentation stages of Legg-Calvé-Perthes disease, the femoral head is biologically plastic and deformable. If it is kept deeply seated within the spherical acetabulum, the acetabulum acts as a mould and the head reossifies as a sphere — the 'ball in a mould' concept. If the head is allowed to extrude or sublux laterally, it deforms into a non-spherical shape and becomes incongruent, leading to early osteoarthritis. The biological principle exploited by surgery is that the plastic head will remodel to the shape of whatever it is moulded against. The decision-making framework. The aim of all treatment is containment — keeping the femoral head within the acetabulum during the plastic phase so it remodels spherically and congruently. Not every Perthes hip needs surgery; the decision integrates age, lateral pillar grade, range of motion, and head-at-risk signs.

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Prognostic factors (decision drivers):

• Age at onset — the single most important factor. In the Herring study no treatment effect was seen below a chronological age of 8 years (or a skeletal age of 6 years), so younger children usually do well non-operatively; children older than 8 years at onset remodel poorly and are more likely to benefit from surgery.
• Lateral pillar grade — A (good regardless), B/B-C (benefits from surgery if older), C (poor regardless).
• Head-at-risk signs — especially lateral subluxation — favour intervention.
• Loss of containment / extrusion and progressive loss of abduction.
• Hinge abduction — if present, varus containment is contraindicated. Non-operative containment — largely abandoned:
• Abduction bracing / casting (e.g. Petrie casts, Scottish-Rite orthosis) was historically used to hold the hip abducted and contained.
• High-quality evidence (including the Herring multicentre study) showed bracing is ineffective at altering outcome and is poorly tolerated — it is no longer recommended as a containment strategy.
• Modern non-operative management focuses on symptomatic care: activity modification, physiotherapy to maintain range of motion (especially abduction and internal rotation), analgesia, and observation — appropriate for the younger child and lateral pillar A. Indications for surgical containment:
• Best-supported indication — chronological age older than 8 years at onset with lateral pillar B or B/C — this is the group with demonstrated benefit from operative containment (femoral or pelvic osteotomy) in the Herring multicentre prospective study. (Wiig used a chronological-age threshold of 6 years with greater than 50% head necrosis to recommend femoral varus osteotomy.)
• Progressive subluxation / extrusion of the head (head-at-risk signs) with loss of containment.
• Failure to maintain containment with conservative measures in an at-risk hip.
• Lateral pillar B/B-C in the early (initial/fragmentation) stage while the head is still reducible and congruent in abduction. Contraindications to containment (varus/Salter):
• Healed or late reossification stage — head no longer plastic, deformity fixed.
• Hinge abduction confirmed on dynamic arthrogram — abduction worsens congruity (needs valgus osteotomy or shelf).
• Uncontainable head (markedly enlarged coxa magna that cannot be seated) — consider lateral shelf / Chiari salvage.
• Stiff, incongruent hip with fixed deformity. Prerequisite assessment before surgery:
• Dynamic arthrogram under anaesthesia — the key planning step. Confirms the head reduces and is congruent in abduction and internal rotation and excludes hinge abduction.
• Restore range of motion first if the hip is stiff (traction, adductor release / physiotherapy) — a hip must abduct before it can be contained.

The goal is to keep the deformable femoral head seated within the acetabular mould so it reossifies as a sphere. Containment can be achieved on the femoral side (redirect the head into the socket by reorienting the proximal femur), the pelvic side (redirect the acetabulum to cover the head), or both. Salvage procedures (shelf, Chiari) are used when the head is too large or uncontainable, or when hinge abduction is present. Every case is opened with a dynamic arthrogram under anaesthesia to confirm the head reduces and is congruent in abduction and to exclude hinge abduction before any bone is cut.

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Salvage and hinge-abduction procedures. When the head is too large to contain anatomically, or hinge abduction is present, containment is abandoned in favour of realignment or augmentation: a shelf acetabuloplasty augments lateral coverage of a large head with a bone shelf; a Chiari osteotomy medialises and salvages an incongruent/uncontainable hip by capsular metaplasia; and a valgus (± extension) osteotomy is the procedure of choice for hinge abduction, because the head is congruent in adduction — bringing that congruent medial portion under load relieves the hinge and improves abduction and gait.

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Post-operative care by procedure:

• Femoral osteotomy — hip spica or protected weight-bearing depending on fixation rigidity; plate removal commonly at 6-12 months once united.
• Salter osteotomy — single hip spica for approximately 6 weeks, then mobilise; remove threaded wires once healed.
• Rehabilitation — regain abduction and internal rotation; physiotherapy; monitor for trochanteric overgrowth and leg-length discrepancy to maturity. Complications

Critical decision points and exam traps

Epidemiology and pathoanatomy. Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the proximal femoral epiphysis in the growing child. Interruption of blood supply (predominantly via the lateral epiphyseal vessels of the medial femoral circumflex artery) leads to a self-limiting but staged sequence of necrosis, revascularisation, collapse, and repair. The vulnerable window is the period of necrosis and fragmentation, during which the softened, plastic epiphysis can deform under load. Typical age is 4-8 years with a male predominance of about 4-5:1; disease is bilateral in up to 10-15% (usually asynchronous — synchronous bilateral symmetrical disease should prompt consideration of epiphyseal dysplasia or hypothyroidism). Presentation is a painless or mildly painful limp, restricted abduction and internal rotation, and occasionally referred knee pain.

Key timing principle: containment surgery is effective only in stages 1-2 while the head is plastic and reducible. By stages 3-4 the final shape is largely set.

Determinants of outcome. The long-term outcome of Perthes is determined chiefly by the final shape and congruence of the femoral head (Stulberg class). Treatment aims to achieve a spherical or aspherical-congruent (Stulberg I-III) hip and to avoid an incongruent (IV-V) hip, which leads to early osteoarthritis. The most important prognostic factors are age at onset, lateral pillar grade, final head sphericity and congruence, head-at-risk signs (especially lateral subluxation/extrusion), and range of motion maintained throughout the disease. Femoral vs Salter — outcome comparison. Comparative series show no consistent difference in final sphericity or congruence (Stulberg outcome) between femoral and Salter osteotomy when the hip is congruent and reducible — both achieve containment. In the most-cited direct comparison (Kitakoji et al., 2005), the two procedures produced equivalent head sphericity and hip congruity, but the Salter group had a neck-shaft angle, acetabular coverage, and articular-trochanteric distance closer to normal, and avoided the surgical scarring and coxa vara seen after femoral osteotomy. Choice is guided by deformity pattern, surgeon experience, and limb-length considerations.

Long-term and natural history. Many patients function well into adulthood; significant osteoarthritis typically presents in the 5th-6th decade, correlating with Stulberg class. Stulberg I-II carries minimal long-term OA risk; Stulberg III moderate OA in middle age; Stulberg IV-V a high risk of early, severe OA requiring joint-preserving osteotomy or arthroplasty. Counselling should be realistic: containment improves the odds of a congruent hip but cannot guarantee a normal hip, especially in older children and lateral pillar C.

Further reading:

• Catterall A (1971). The natural history of Legg-Calvé-Perthes disease. J Bone Joint Surg Br 53(1):37-53. — Original Catterall classification and the head-at-risk signs guiding prognosis.
• Salter RB (1984). The present status of surgical treatment for Legg-Perthes disease. J Bone Joint Surg Am. — Rationale and technique for innominate osteotomy as a containment procedure.
• Joseph B, Nair NS, Narasimha Rao K, et al. Optimal timing for containment surgery for Perthes disease. J Pediatr Orthop. — Evidence that containment is effective only in the early (avascular/fragmentation) stages.