Legg Calve Perthes Disease Joseph Donnelly, M.D. December 10, 2001

Overview History Epidemiology/ Etiology Pathogenesis Radiographic stages Presentation/ Exam Imaging Treatment

History Late 19th century: “hip infections” that resolved without surgery First described in 1910 Early path studies: cartilaginous islands in the epiphysis -described 1910 independently by Legg, Calve, Perthes, and Waldenstrom -Legg= “obscure affectation of the hip”, thought secondary to pressure injury flattening the femoral head -Calve: same year, 10 cases non inflamm/self limiting disease due to delayed osteogenesis. Also reported coxa vara and increased femoral head size -Perthes- “arthritis deformans juveniles, possible inflammatory condition -Waldenstrom: thought it was TB

Epidemiology Disorder of the hip in young children Usually ages 4-8yo As early as 2yo, as late as teens Boys:Girls= 4-5:1 Bilateral 10-12% No evidence of inheritance -incidence of positive family hx ranges from 1.6% to 20%, but no hard evidence of predisposition -is more common in certain geographic areas (urban>rural)=nutritional?, later born children, strong association with ADHD (33%)

Etiology Unknown Past theories: infection, inflammation, trauma, congenital Most current theories involve vascular compromise Sanches 1973: “second infarction theory” -Phemister- thought it was infectious but cx neg -Axhausen- thought bacillary embolism with weak infection which healed quickly -1975 Matsoukas showed association with prenatal rubella -1973 Sanches, infarcted animal femoral heads, unable to produce typical histologic picture of LCPdz with one infarction, could do it with a second. Supported by Inoue using human histologic material

Etiology: blood supply -blood supply description (terminology)varies -3 main sources to the proximal femur: 1)extracapsular ring, 2)ascending cervical (retinacular branches) vessels 3)artery of the ligamentum teres -extracapsular ring: med and lat fem circumflex, gives rise to ascending cervical branches (extracapsular) which give of metaphyseal and epiphyseal branches -ant portion=mainly lat fem circ, post/lat/med=med fem circ -Chung found that greatest volume of flow= from lat ascending cervical (end of med fem circ)

Pathogenesis Histologic changes described by 1913 Secondary ossification center= covered by cartilage of 3 zones: Superficial Epiphyseal Thin cartilage zone Capillaries penetrate thin zone from below -few human specimens have been studied, each showing only a stage of the dz and usually from sample of just one part of the involved head. Histologically not well illucidated

Pathogenesis: cartilage zones -Superficial zone=like adult articular cartilage -epiphyseal (middle) cartilage zone= becomes thinner as skeleton matures, epiphyseal bone enlarges -Deep thin zone= small clusters of cartilage cells that hypertrophy and degenerate -capillaries from below

Pathogenesis Epiphyseal cartilage in LCP disease: Superficial zone is normal but thickened Middle zone has 1)areas of extreme hypercellularity in clusters and 2)areas of loose fibrocartilaginous matrix Superficial and middle layers nourished by synovial fluid Deep layer relies on blood supply -changes in zone 2 are abnormal, have different histochemical and US properties vs normal, also see small 2ndary ossification centers directly on the abnormal cartilage matrix -synovial fluid nourishes 2 superficial layers, continue to proliferate -deep layer affected by ischemic process

-a) superficial zone: area of disorganized cartilage -c) junction btwn normal and abnormal epiphyseal cartilage, note hypercellularity -d) extensive abnormal cartilage, bone forms directly on abnormal cartilage

Pathogenesis Physeal plate: cleft formation, amorphis debris, blood extravasation Metaphyseal region: normal bone separated by cartilaginous matrix Epiphyseal changes can be seen also in greater trochanter, acetabulum -physeal plate: thinner than normal, irregular cell columns and cartilage masses -metaphysis: cartilage does not ossify, proliferates with bone, causes tongues of cartilage extending into metaphysis -skeletal surveys shows contour irregularities in 48% of normal contralateral capital epiphysis, suggesting it is a generalized disorder, more appropriately named a syndrome

Radiographic Stages Four Waldenstrom stages: 1) Initial stage 2) Fragmentation stage 3) Reossification stage 4) Healed stage

Initial Stage Early radiographic signs: Failure of femoral ossific nucleus to grow Widening of medial joint space “Crescent sign” Irregular physeal plate Blurry/ radiolucent metaphysis -growth failure due to lack of blood supply -affected femoral ossific nucleus appears radiodense (relative osteopenia of surrounding bone vs. increased mass in that area?) -affected femoral head appears smaller vs. other side -wide med joint space due to: synovitis? Decreased head volume from necrosis and collapse? Due to increased blood flow to soft tissues (eg. Lig teres) causing lateral displacement? Most likely due to epiphyseal cartilage hypertrophy (x-ray phenomenon) -crescent sign= subchondral radiolucent zone, likely results from a subchondral stress fracture and the extent of this zone determines the extent of the necrotic fragment

Initial Stage -note smaller, denser ossific nucleus on L hip -crescent (fracture) sign -irregular physeal plate -blurry, radiolucent metaphysis

Initial Stage -same on frog

Fragmentation Stage Bony epiphysis begins to fragment Areas of increased lucency and density Evidence of repair aspects of disease -increased radiodensity due to new bone forming on old bone

Fragmentation Stage -fragmented epiphyseal bone, radiodense and lucent areas

Fragmentation Stage

Reossification Stage Normal bone density returns Alterations in shape of femoral head and neck evident

Reossification Stage -note shape deformity on R vs L

Reossification Stage

Healed Stage Left with residual deformity from disease and repair process Differs from AVN following Fx or dislocation -AVN process after fx/dislocation does not undergo fragmentation

Presentation Often insidious onset of a limp C/O pain in groin, thigh, knee 17% relate trauma hx Can have an acute onset -must recognize thigh & knee pain as possible hip pathology -pain usually mild and relieved by rest, often present late due to mild sx

Physical Exam Decreased ROM, especially abduction and internal rotation Trendelenburg test often positive Adductor contracture Muscular atrophy of thigh/buttock/calf Limb length discrepency -early decreased abduction due to synovitis/spasm, may become permanent after development of femoral head deformity -adduction contracture due to long standing spasm -atrophy due to disuse due to pain, shows long standing nature -short limb due to head collapse= poor prognosis

Imaging AP pelvis Frog leg lateral Key= view films sequentially over course of dz Arthrography MRI role undefined -frog leg= better for crescent sign -compare films with previous to determine change -arthrography can show status of cartilage not shown on x-ray, check ROM to r/o hinging abduction -hinging abduction due to large femoral head extruding laterally & hinging over edge of acetabulum

Differential Diagnosis Important to rule out infectious etiology (septic arthritis, toxic synovitis) Others: Chondrolysis -Neoplasm JRA -Sickle Cell Osteomyelitis -Traumatic AVN Lymphoma -Medication

Radiographic Classifications Describe extent of epiphyseal disease Catterall classification= most commonly used 4 groups based on amount of femoral head involvement Also presence of sequestrum, metaphyseal rxn, subchondral fx

Group I -25% of anterocentral head involved -no sequestrum, no subchondral fx’s, normal metaphysis

Group II -50% of anterolateral region involved -evidence of sequestrum/ subchondral (anterior) fx, med/lat pillars intact

Group III -75% of head involved -large sequestrum, lat pillar (column) involved, sclerotic junction btwn normal/abnormal -subchondral fx line extends into post ½ of epiphysis

Group IV -whole head involved, widespread epiphyseal collapse -diffuse or central metaphyseal lesion -Posterior remodeling of ephiphysis -poor prognosis

Lateral Pillar Classification 3 groups: A) no lateral pillar involvment B) >50% lat height intact C) <50% lat height intact

Salter-Thompson Classification Simplification of Catterall Based on status of lateral margin of capital femoral epiphysis Group A (Catterall I & II equivalent) Group B (Catterall III & IV equivalent)

Prognosis 60% of kids do well without tx AGE is key prognostic factor: <6yo= good outcome regardless of tx 6-8yo= not always good results with just containment >9yo= containment option is questionable, poorer prognosis, significant residual defect -Catterral 1 and usually 2 do well without treatment

Prognosis Flat femoral head incongruent with acetabulum= worst prognosis Do not treat in reossification stage (>15mos) -to late to treat after 15mos

Non-operative Tx Improve ROM 1st Bracing: Removable abduction orthosis Pietrie casts Hips abducted and internally rotated Wean from brace when improved x-ray healing signs -abduction usually affected most of ROM -use PT to regain abduction (overcome spasm) and internal rotation -may require several weeks of abduction traction -don’t start bracing until abd/int rot restored to normal -arthrography pre-bracing to determine congruency throughout ROM -head collapse is independent of weight bearing, not necessarily NWB -hips braced in abd/ int rotation to transmit weight over wide area of acetabulum, prevents head collapse

Bracing

Non-operative Tx Check serial radiographs Continue bracing until: Q3-4 mos with ROM testing Continue bracing until: Lateral column ossifies Sclerotic areas in epiphysis gone Cast/brace uninvolved side -Study by Futami and Suzuki 1997, 6% of uninvolved contralat hips develop LCP when unbraced, 0 when braced -length of casting usually 6 weeks to start out

Operative Tx If non-op tx cannot maintain containment Surgically ideal pt: 6-9yo Catterral II-III Good ROM <12mos sx In collapsing phase

Surgical Tx Surgical options: Excise lat extruding head portion to stop hinging abduction Acetabular (innominate) osteotomy to cover head Varus femoral osteotomy Arthrodesis

Varus Osteotomy

Late Effects of LCP Coxa magna Physeal arrest patterns Irregular head formation Osteochondritis dessicans -coxa magna due to ossiffication of hypertrophied articular cartilage -OD=rare, occurs with the late onset of dz and with prolonged ineffectual repair stage

The End