Legg‑Calvé‑Perthes — Staging & Prognosis

Overview & Pathophysiology

Legg-Calvé-Perthes disease (LCPD) is idiopathic avascular necrosis (osteonecrosis) of the capital femoral epiphysis in children, named after three surgeons who independently described it in 1910 (Georg Legg, Jacques Calvé, Georg Perthes). The condition involves temporary interruption of the blood supply to the femoral head, causing ischaemic necrosis of the epiphyseal bone, followed by resorption of dead bone, revascularisation, and attempted repair by subchondral bone regeneration. The ultimate shape of the femoral head after healing determines the long-term outcome — a round head within a congruent acetabulum → good prognosis; a flat, aspherical head (coxa plana) with a large femoral head (coxa magna) → poor prognosis, early osteoarthritis.

Epidemiology: incidence approximately 1–10 per 100,000 children per year; peak age 4–8 years (range 2–12 years); male:female 4–5:1; White children predominantly; bilateral in 10–12% of cases (typically asynchronous — different stages in each hip); associated with growth retardation, low birth weight, short stature, and skeletal age delay; socioeconomic factors and passive tobacco smoke exposure have been reported as risk factors
Pathophysiology: the blood supply to the capital femoral epiphysis in children is particularly vulnerable — the lateral epiphyseal vessels (branches of the medial circumflex femoral artery) are the primary supply; they run across the femoral neck and enter the epiphysis through the periphery; these vessels are at risk from increased intracapsular pressure (e.g., from synovial effusion), trauma, thrombotic events (coagulation abnormalities — elevated Factor V Leiden, protein C/S deficiency — found in some cases), or reduced blood flow from other causes; the cause in most cases remains unknown (hence `idiopathic`); whatever the mechanism, ischaemia of the femoral epiphysis is followed by a predictable biological sequence of events over 2–4 years
Biological stages: Stage 1 — ischaemia/early necrosis (new bone formation ceases; the epiphysis becomes radiodense relative to surrounding osteoporotic bone; subchondral fracture may occur; joint effusion); Stage 2 — fragmentation/resorption (dead bone is resorbed; the epiphysis appears fragmented on X-ray; the physis is compressed; the head may collapse and lose sphericity); Stage 3 — reossification/healing (new bone laid down in the resorbed areas; the density of the epiphysis returns; the final shape of the femoral head is determined during this stage — it is `plastic` and can be influenced by the forces applied to it); Stage 4 — healed (ossification complete; the final femoral head shape is fixed)

Staging Systems

Classification	Basis	Categories	Clinical Use
Waldenstrom stages (radiological progression)	Describes the biological stages of LCPD visible on plain X-ray	Stage 1 (Initial/Ischaemic): increased density, may see subchondral fracture; Stage 2 (Fragmentation): resorption, fragmented appearance; Stage 3 (Reossification/Healing): new bone deposition, density returning; Stage 4 (Residual/Healed): final shape established	Communicates the stage of disease; most interventions are targeted to the early fragmentation stage when the femoral head is most `plastic` and containment has the greatest potential to influence final head shape
Catterall classification (1971)	Based on the extent of epiphyseal involvement seen on AP and lateral X-ray at the fragmentation stage	Group I: anterior head involved only (<25%); Group II: anterior head with sequestrum, preserved metaphyseal reaction on medial and lateral sides; Group III: large sequestrum (>75% involvement), lateral column partially involved; Group IV: total epiphyseal involvement (100%)	Historically important; Groups I–II generally good prognosis; Groups III–IV poor; superseded by the simpler Herring lateral pillar classification for most purposes; difficult interobserver reproducibility
Herring lateral pillar classification (1992, revised 2004) — THE MOST CLINICALLY IMPORTANT	Assesses the height of the lateral pillar of the femoral head (the lateral 15–30% of the epiphysis on AP X-ray) during the fragmentation stage; the lateral pillar is the structural column most critical for maintaining femoral head height and preventing collapse	Group A: lateral pillar height fully maintained (>100% of original height); Group B: lateral pillar height maintained >50% of original; Group B/C border: lateral pillar >50% height BUT narrow (<3 mm) OR barely ossified; Group C: lateral pillar height <50% of original (severe collapse)	Best validated classification for prognosis and treatment decisions; Group A = almost universally good outcome; Group B = intermediate (age-dependent — see below); Group C = poor outcome regardless of treatment; the Herring classification was validated in the landmark multicentre Herring trial (2004) which also established age at onset as the most important outcome modifier
Stulberg classification (outcome assessment)	Assesses the final shape of the femoral head and congruence of the hip joint after healing is complete; applied in adulthood or at skeletal maturity	Class I: normal spherical head; Class II: spherical head + coxa magna/breva/steep acetabulum (spherical but abnormal size); Class III: non-spherical (ovoid) head, non-spherical acetabulum — congruent; Class IV: flat head, non-spherical acetabulum — congruent flat joint; Class V: flat head, spherical acetabulum — incongruent (worst)	Used for long-term outcome research and prognosis; Classes I–II = excellent prognosis (no or minimal OA); Classes III–IV = fair (moderate OA in 4th–5th decade); Class V = poor (significant early OA); determines prognosis for counselling and planning THA timing

Prognostic Factors

Age at onset — the MOST IMPORTANT prognostic factor: children who develop LCPD younger than 6 years have an inherently better prognosis than those who develop it older; younger children have more growth remaining, the femoral head has greater remodelling potential, and the acetabulum is more plastic and can adapt to a slightly abnormal femoral head shape; the landmark Herring multicentre RCT (2004) stratified outcomes by age — children <8 years at symptom onset with Group B lateral pillar had equivalent outcomes with treatment (bracing/containment surgery) or symptomatic management (no significant difference — controversial finding); children ≥8 years at symptom onset with Group B or B/C had significantly better outcomes with surgical treatment (containment osteotomy) versus symptomatic management
Herring lateral pillar: Group A — good prognosis regardless of age or treatment; Group C — poor prognosis regardless of treatment; Group B — age-dependent outcome (see above)
Gage`s head-at-risk signs: radiological signs that indicate the femoral head is at risk of severe deformity; (1) small V-shaped osteoporotic segment in lateral epiphysis; (2) calcification lateral to the epiphysis; (3) diffuse metaphyseal reaction; (4) lateral subluxation of the femoral head (loss of Shenton`s line continuity); (5) horizontal growth plate; presence of 2 or more of these signs indicates a head at risk and is an indication for active containment treatment
Range of hip motion: loss of hip motion (particularly abduction and internal rotation) is associated with worse outcome — a `hinged` abduction pattern (the femoral head levers against the lateral acetabular rim on abduction — causing pain and blocking motion) indicates loss of sphericity and congruence and predicts poor outcome

Management

Scenario	Age / Herring Group	Management	Evidence / Notes
Symptomatic management (activity modification)	Any age; Group A; children <8 years Group B	Activity modification (avoid high-impact activities during active fragmentation); physiotherapy to maintain hip range of motion (ROM); NSAIDs for pain; hydrotherapy (non-weight-bearing exercise); Petrie abduction casts for regaining abduction in `hinged` hips; no bracing (bracing no longer recommended — Herring RCT showed no benefit over symptomatic management in children <8 with Group B)	Herring multicentre RCT 2004: Group A — excellent regardless of treatment; Group B under age 8 — no significant benefit of containment treatment over symptomatic management; Group B/C and C — worse outcome regardless; management most impactful in Group B age ≥8 years
Containment — rationale	Group B or B/C; age ≥8 years at onset; head at risk signs	Containment places the vulnerable `plastic` femoral head within the mould of the acetabulum during the reossification stage; the acetabulum acts as a biological mould to encourage a spherical femoral head shape during healing; containment can be achieved surgically or rarely by bracing	The theoretical basis for all containment interventions; most evidence supports surgical containment for Group B age ≥8 years and Group B/C (all ages are debated)
Surgical containment — femoral osteotomy	Group B / B/C; age ≥8 years; early fragmentation stage; adequate hip motion	Varus derotation osteotomy (VDRO) of the proximal femur — redirects the femoral head into the acetabulum by creating a varus position of the neck (places the femoral head more directly under the acetabular dome); typically 15–20° of varus; must be performed before the `plastic` window closes (early fragmentation); followed by removal of the hardware after healing	Effective and reproducible; the most commonly used surgical containment method in the UK; produces a temporary Trendelenburg gait (from the varus position — improved by the remodelling that occurs with growth); secondary coxa vara if over-corrected
Surgical containment — pelvic osteotomy	Alternative or additional to femoral osteotomy; Salter or Dega innominate osteotomy	Redirects the acetabulum to provide better anterior and lateral coverage of the femoral head; may be combined with femoral VDRO for maximum containment; Salter osteotomy well-established for LCPD containment	Particularly useful when femoral head cannot be adequately contained by femoral osteotomy alone (e.g., large lateral pillar collapse or significant lateral subluxation)
Hinged abduction pattern	Any age; usually later disease or healed stage; loss of abduction with femoral head levering against acetabular rim	Valgus extension osteotomy (Chiari osteotomy or shelf procedure) — redirects the femoral head below the acetabular rim; improves congruence; reduces levering; Shelf acetabuloplasty — builds up the acetabular rim to provide coverage for a flat femoral head that has extruded laterally	Indicated for symptomatic hinged abduction; not a `containment` procedure per se — it is a salvage procedure for established deformity; may reduce pain and improve function before THA becomes necessary

Exam Pearls

LCPD: idiopathic AVN of capital femoral epiphysis; peak age 4–8 years; boys 4–5:1; presents with painless limp, groin/knee pain, limited internal rotation and abduction; bilateral 10–12%
Herring lateral pillar: most clinically important classification; measured at fragmentation stage; Group A (>100% height) — excellent always; Group B (>50%) — age-dependent; Group B/C — borderline; Group C (<50%) — poor always
Age at onset = MOST IMPORTANT prognostic factor: <6 years = generally good; <8 years + Group B = symptomatic management (Herring RCT — no benefit from containment); ≥8 years + Group B or B/C = surgical containment significantly better outcome (Herring RCT)
Waldenstrom stages: Initial → Fragmentation (critical treatment window) → Reossification → Healed; treatment must be in fragmentation/early reossification
Gage`s head-at-risk signs: 5 signs (V-shaped osteoporosis, lateral calcification, metaphyseal reaction, lateral subluxation, horizontal physis); ≥2 signs = head at risk = containment indicated
Stulberg outcome: Classes I–II (spherical head = good, minimal OA); Class III–IV (ovoid/flat congruent = moderate OA in 4th–5th decade); Class V (flat head in spherical acetabulum = incongruent = early severe OA)
Containment rationale: acetabulum acts as biological mould during plastic reossification stage; surgical containment — VDRO (most common) or pelvic osteotomy (Salter); bracing NOT recommended (no evidence)
Hinged abduction: femoral head levers against lateral acetabular rim → pain + limited ROM → poor prognosis; Petrie casts to regain abduction early; valgus osteotomy or shelf procedure for established hinged abduction
Long-term: 50% of Stulberg III/IV patients develop significant OA by age 50; THA when OA symptomatic; young patients may benefit from periacetabular osteotomy (PAO) or femoral osteotomy to delay THA if cartilage preserved

Legg‑Calvé‑Perthes — Staging & Prognosis

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