# CIM Case: Perthes Disease ## Clinical Scenario **Patient:** 6-year-old boy **Presentation:** 3-month history of progressive limp and intermittent left hip pain, referred to groin and anterior thigh, worse with activity **Relevant history:** No trauma, no recent illness, previously active and healthy, pain sometimes wakes him at night, no fever, no weight loss **Examination findings:** - Antalgic gait with shortened stance phase on left - Left leg held in slight flexion and external rotation - Reduced hip flexion (100° vs 130°), limited internal rotation (10° vs 40°), limited abduction (20° vs 45°) - Positive log roll test (pain with rotation) - No leg length discrepancy currently - Trendelenburg negative - No muscle wasting - Knee examination normal bilaterally --- ## Investigations Provided ### Laboratory Results | Test | Result | Normal Range | Interpretation | |------|--------|--------------|----------------| | Hb | 128 g/L | 115-135 g/L | Normal | | WCC | 7.5 ×10⁹/L | 5-15 ×10⁹/L | Normal | | Platelets | 298 ×10⁹/L | 150-400 ×10⁹/L | Normal | | ESR | 8 mm/hr | <10 mm/hr | Normal (helps exclude infection/inflammation) | | CRP | <3 mg/L | <5 mg/L | Normal | ### Imaging **Image 1: AP Pelvis and Frog-leg Lateral Radiographs** **Radiological features:** - Left femoral epiphysis smaller and denser than right (sclerosis) - Widening of medial joint space (lateral subluxation) - Crescent sign visible on lateral (subchondral fracture) - Metaphyseal lucency present - Physis appears horizontal - Lateral pillar involvement - partial collapse (Herring B) - Catterall Group III (50-75% head involvement) **Image 2: MRI of Pelvis (if obtained)** **MRI findings:** - Low signal on T1 in anterolateral femoral epiphysis - High signal on T2/STIR indicating oedema and revascularisation - Extent of necrosis more clearly defined - No physeal bar - Labral changes minimal ## Questions & Model Answers **Clinical Diagnosis: Legg-Calvé-Perthes Disease (LCPD)** **Diagnostic Features:** - Classic age (4-8 years), male predominance (4:1) - Insidious onset limp with activity-related hip pain - Limited ROM, especially internal rotation and abduction - Radiographic changes of AVN **Staging Systems:** **Waldenström Stages (Disease Progression):** | Stage | Duration | Radiographic Features | |-------|----------|----------------------| | **Initial (necrosis)** | 6 months | Sclerosis, crescent sign | | **Fragmentation** | 6-12 months | Head fragmentation, lateral pillar collapse | | **Reossification** | 1-3 years | New bone formation | | **Healed** | - | Remodelled head (spherical vs aspherical) | **Herring Lateral Pillar Classification (at fragmentation):** | Type | Description | Prognosis | |------|-------------|-----------| | **A** | Lateral pillar full height | Excellent | | **B** | >50% lateral pillar height preserved | Good if <8 years | | **B/C border** | 50% height, narrow or depressed | Fair | | **C** | <50% lateral pillar height | Poor | **This Patient:** Herring B (partial lateral pillar collapse, >50% height preserved) > **Consultant Tip:** Herring classification is made at the BEGINNING of fragmentation stage. It's the most important prognostic classification. **Prognostic Factors:** **Age at Onset (Most Important):** | Age | Prognosis | Rationale | |-----|-----------|-----------| | <6 years | Excellent | More time for remodelling before skeletal maturity | | 6-8 years | Good | Moderate remodelling potential | | >8 years | Poor | Limited remodelling potential | **Radiological Prognostic Factors:** **Favourable:** - Herring A or B - Less than 50% head involvement - No lateral subluxation - No metaphyseal cysts - Spherical head at healing **Unfavourable (Head-at-Risk Signs):** | Sign | Description | |------|-------------| | **Gage sign** | V-shaped lucency in lateral epiphysis | | **Lateral subluxation** | Widened medial joint space | | **Horizontal physis** | Growth plate horizontalization | | **Metaphyseal cysts** | Lucencies at physis | | **Calcification lateral to epiphysis** | Indicates extrusion | **Stulberg Classification (Outcome):** | Class | Head Shape | Congruency | Prognosis | |-------|------------|------------|-----------| | I | Spherical | Concentric | Excellent | | II | Spherical | Coxa magna/brevis | Good | | III | Ovoid | Congruent | Fair | | IV | Flat | Incongruent | Poor | | V | Flat | Severe incongruence | Poor (early OA) | **This Patient:** Age 6 with Herring B - moderate prognosis, may benefit from containment treatment. > **Consultant Tip:** Age >8 years + Herring B/C or C = poor prognosis regardless of treatment. These are the "bad" Perthes. **Principle of Containment:** - Keep the femoral head well seated within the acetabulum - Acetabulum acts as a "mould" during reossification - Prevents lateral extrusion and promotes spherical remodelling - Head must be in the "biological plastic" phase (fragmentation stage) **Treatment Algorithm:** **Observation Indications:** - Age <6 years regardless of classification - Herring A at any age - Minimal symptoms, good ROM **Containment Treatment Indications:** - Age >6 years with Herring B or B/C - Loss of containment (lateral subluxation) - Significant loss of ROM **Containment Options:** | Method | Type | Description | |--------|------|-------------| | **Abduction bracing** | Non-operative | Scottish Rite orthosis (rarely used now) | | **Petrie casts** | Non-operative | Abduction casts (poor compliance) | | **Femoral varus osteotomy** | Operative | Redirect head into acetabulum | | **Innominate osteotomy** | Operative | Redirect acetabulum over head | | **Shelf acetabuloplasty** | Operative | Increase coverage, older children | **Operative Containment:** **Femoral Varus Osteotomy:** - Most common surgical option - Intertrochanteric osteotomy with blade plate fixation - 15-25° valgus correction (to produce 10-15° varus) - Improves coverage but causes LLD, Trendelenburg **Pelvic Osteotomy (Salter):** - Redirects acetabulum anterolaterally - Better for older children with stiff hips - Can combine with femoral osteotomy **This Patient:** Age 6 with Herring B - at threshold for containment surgery. Would recommend ROM exercises initially, reassess in 6-8 weeks. > **Consultant Tip:** Surgery doesn't change the disease - it optimises the environment for healing. The head will heal; we want it to heal round. **Principles:** - ROM restoration is critical before any surgical containment - Stiff hip cannot be contained - Synovitis and muscle spasm cause restriction **Non-operative ROM Management:** **First Line:** - Activity modification (avoid running, jumping) - NSAIDs for synovitis - Physiotherapy for gentle stretching - Pool therapy (non-weight-bearing abduction exercises) **Second Line (if refractory):** - Hospital admission - Skin traction (1-2 kg) for 1-2 weeks - Traction in abduction position - Consider epidural for pain control **Third Line (rare):** - Adductor tenotomy - Psoas lengthening - Examination under anaesthesia with arthrogram **Assessment of ROM Restoration:** | Motion | Target | This Patient | |--------|--------|--------------| | Flexion | >100° | 100° ✓ | | Abduction | >30° | 20° ✗ | | Internal rotation | >20° | 10° ✗ | **This Patient's Management:** 1. Cease weight-bearing sports 2. NSAIDs (ibuprofen 10mg/kg TDS) 3. Physiotherapy referral 4. Pool exercises 5. Review in 4-6 weeks with repeat X-ray 6. If ROM not improved, consider traction **If ROM Restored and Surgery Indicated:** - Proceed to containment surgery (femoral or pelvic osteotomy) - Timing at beginning of fragmentation stage > **Consultant Tip:** Never do containment surgery on a stiff hip. The head will hinge rather than reduce. ROM first, surgery second. **Natural History:** - Disease is SELF-LIMITING - all heads revascularise - Process takes 2-4 years - Outcome depends on shape of head at skeletal maturity - Deformed head leads to early osteoarthritis **Timeline:** | Phase | Duration | Events | |-------|----------|--------| | Ischemia | Weeks-months | Initial insult, sclerosis | | Revascularisation | 6-12 months | Fragmentation, resorption | | Reossification | 1-3 years | New bone formation | | Residual | Lifelong | Remodelling until skeletal maturity | **Long-term Outcomes by Stulberg Class:** | Stulberg Class | Head Shape | 25-year OA Risk | 50-year OA Risk | |----------------|------------|-----------------|-----------------| | I-II | Spherical | <5% | <10% | | III | Ovoid, congruent | 20% | 50% | | IV-V | Flat, incongruent | 50% | 90% | **Factors Predicting Poor Long-term Outcome:** - Age at onset >8 years - Herring C classification - Persistent lateral subluxation - Coxa magna with aspherical head - Premature physeal closure - Hinge abduction **Hinge Abduction:** - Deformed head "hinges" on lateral acetabular margin - Pain with abduction - Poor prognosis, difficult to treat - May require salvage procedures (shelf, Chiari, valgus osteotomy) > **Consultant Tip:** Young + Herring A = great outcome (90% Stulberg I-II). Old + Herring C = poor outcome regardless of treatment (most Stulberg IV-V). **Differential Diagnosis of Limp in a Child:** **Inflammatory/Infectious:** | Condition | Distinguishing Features | |-----------|------------------------| | **Transient synovitis** | Younger (3-6 years), acute onset, resolves 1-2 weeks, normal X-ray | | **Septic arthritis** | Febrile, toxic, elevated WCC/CRP/ESR, urgent aspiration | | **Osteomyelitis** | Fever, point tenderness metaphysis, elevated markers | | **JIA** | Prolonged symptoms, other joints, systemic features | **Other Hip Pathology:** | Condition | Distinguishing Features | |-----------|------------------------| | **SUFE** | Older (10-16), obese, physeal widening, metaphyseal blanch | | **DDH (late)** | Female, abnormal Shenton's line, no AVN changes | | **Multiple epiphyseal dysplasia (MED)** | Bilateral, symmetrical, other epiphyses involved | | **Spondyloepiphyseal dysplasia** | Bilateral, spine involvement, short stature | | **Meyer dysplasia** | <4 years, irregular ossification, normal outcome | **Key Investigations to Differentiate:** | Investigation | Purpose | |---------------|---------| | **FBC, CRP, ESR** | Exclude infection (normal in Perthes) | | **X-ray pelvis** | Characteristic Perthes changes | | **Ultrasound** | Effusion (present in Perthes but also synovitis/sepsis) | | **MRI** | Extent of necrosis, exclude tumour/infection | | **Aspiration** | If septic arthritis suspected | **This Patient:** - Age and sex typical for Perthes - Insidious onset (not acute like transient synovitis) - Normal inflammatory markers (not infection) - Unilateral with classic X-ray changes - **Diagnosis: Perthes disease confirmed** > **Consultant Tip:** The irritable hip algorithm: Kocher criteria help, but if any doubt, aspirate. Never miss septic arthritis. --- ## Key Teaching Points ### Pattern Recognition **This pattern suggests Perthes Disease:** - School-age boy (4-8 years) with insidious limp - Groin/thigh pain worse with activity - Limited internal rotation and abduction - Radiographs: small, dense, fragmented femoral head **Distinguish from Transient Synovitis:** | Feature | Perthes | Transient Synovitis | |---------|---------|---------------------| | Onset | Insidious (weeks) | Acute (days) | | Duration | Months-years | 1-2 weeks | | X-ray | Abnormal | Normal | | Age | 4-8 years | 3-6 years | | Outcome | Permanent changes | Complete resolution | ### Critical Management Points 1. **Age is the most important prognostic factor** - younger is better 2. **Herring classification at fragmentation** - determines treatment and prognosis 3. **ROM must be restored before surgery** - stiff hip cannot be contained 4. **Disease is self-limiting** - treatment optimises outcome, doesn't cure 5. **Head-at-risk signs indicate need for containment** - lateral subluxation, Gage sign 6. **Long-term OA depends on Stulberg class** - aspherical heads fare poorly --- ## Common Examiner Follow-ups **Q: "When would you do an MRI?"** MRI indications in Perthes: - **Early diagnosis:** X-ray equivocal but clinical suspicion high - **Extent of necrosis:** Planning treatment, assessing lateral pillar - **Atypical presentation:** Exclude other pathology (tumour, infection) - **Bilateral involvement:** Consider MED or other skeletal dysplasia - **Poor response to treatment:** Assess for complications MRI provides earlier detection than X-ray and better defines extent of involvement. --- **Q: "This child is 9 years old with Herring C. What would you do?"** This is a "bad" Perthes with poor prognosis regardless of treatment: - **Expectation setting:** Counsel family about likely outcome (Stulberg IV-V) - **ROM maintenance:** Priority is preventing stiff hip - **Containment role limited:** Evidence does not show containment helps Herring C at this age - **Observe:** Serial X-rays, physiotherapy, activity modification - **Salvage surgery later if needed:** Shelf acetabuloplasty, Chiari osteotomy, valgus osteotomy for hinge abduction, or eventual hip replacement Surgery for poor prognosis Perthes is controversial - may not change outcome. --- **Q: "What is the evidence for containment surgery?"** Key evidence: - **Herring Prospective Study (2004, JBJS):** - Age >8 with Herring B/C: surgical containment better than non-operative - Age <8 or Herring A: no benefit from surgery - **Systematic reviews:** Weak evidence overall, no clear superiority of one surgical method - **Recent trends:** Moving away from bracing, selective surgery based on age and classification Bottom line: Surgery helps selected patients (older children with Herring B) but doesn't change outcome for very good or very poor prognosis groups. --- **Q: "What if this child has bilateral involvement?"** Bilateral Perthes (~10-12%): - Usually **asynchronous** (different stages) - Treat each hip according to its stage and classification - If **synchronous and symmetrical** - consider MED or other skeletal dysplasia - Order lateral spine X-ray (vertebral changes in MED) - Consider genetics referral --- ## Related Topics - Developmental Dysplasia of the Hip - Slipped Upper Femoral Epiphysis - Transient Synovitis - Paediatric Hip Fractures - Proximal Femoral Osteotomy - Pelvic Osteotomies