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

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

3. 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

4. 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%)

5. 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

6. 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)

7. 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

8. 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

9. 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

10. -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

11. 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

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

13. 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

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

15. Initial Stage
-same on frog

16. 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

17. Fragmentation Stage
-fragmented epiphyseal bone, radiodense and lucent areas

18. Fragmentation Stage

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

20. Reossification Stage
-note shape deformity on R vs L

21. Reossification Stage

22. 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

23. 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

24. 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

25. 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

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

27. 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

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

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

30. 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

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

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

33. 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)

34. 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

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

36. 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

37. Bracing

38. 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

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

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

41. Varus Osteotomy

42. 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

43. The End