Coxa vara

presentation on coxa vara

1. COXA VARA Dr Manoj Das Ortho Resident

2. Coxa Vara Normal neck shaft angle 120-140 deg Neck shaft angle of <120deg is called coxa vara

3. Classification Developmental Isolated (may be bilateral) Associated with a skeletal dysplasia o   Cleidocranial dysostosis o        Metaphyseal dysostosis o        Other skeletal dysplasias Congenital Femoral Deficiency with Coxa Vara   Acquired   Slipped capital femoral epiphysis    Sequelae of avascular necrosis of the femoral epiphysis o        Legg- Calvé - Perthes disease o        Traumatic o        Femoral neck fracture o        Traumatic hip dislocation o        Post reduction for developmental dysplasia of the hip o        Septic necrosis o        Other causes of avascular necrosis of the immature femoral head   Coxa vara associated with pathologic bone disorders - Osteogenesis imperfecta - Fibrous dysplasia - Renal osteodystrophy   - Osteopetrosis -   Other bone-softening conditions affecting the femoral neck  

4. Congenital Coxa Vara Presence at birth extremely rare associated with other congenital anomalies such as - proximal femoral focal deficiency -fibular hemimelia -anomalies in other part of the body such as cleidocranial dyastosis The femoral deformity is present in the subtrochantric area where the bone is bent

5. Congenital Coxa Vara cortices are thickened and may be associated with overlying skin dimples External rotation of the femur with valgus deformity of knee may be noted condition does not resolve and requires surgical management

6. Developmental Coxa Vara Developmental abnormality characterized by primary cartilaginous defect in the femoral neck with an abnormal decrease in the femoral neck–shaft angle shortening of the femoral neck relative overgrowth of the greater trochanter and shortening of the affected lower limb

7. Developmental Coxa Vara Incidence : 1 in 25,000 live births in the Scandinavian population M:F=1:1 unilateral to bilateral cases in between 1:2and 3:1 Bilateral cases more likely to be associated with a generalized skeletal dysplasia

8. Pathophysiology of Developmental Coxa Vara precise cause is unknown primary defect in enchondral ossification of the medial part of the femoral neck

9. Pathophysiology of Developmental Coxa Vara

10. Pathophysiology of Developmental Coxa Vara

11. Pathophysiology of Developmental Coxa Vara

12. Pathophysiology of Developmental Coxa Vara large amounts of fibrous tissue rather than cancellous bone found in the medial part of the metaphysis of the femoral neck the mechanically weak femoral neck could be passively deformed into a varus angulation under the stress of muscle forces and body weight and the capital physis could migrate inferiorly through this weakened portion of the femoral neck

13. Biomechanics compressive force (R) perpendicular to the center of the hip joint physeal cartilage and hyaline cartilage of the acetabulum under compressive force (D), evenly distributed throughout physis is perpendicular to the resultant compressive force R Stresses on the medial side of the femoral neck are compressive (D), whereas on the lateral side are tensile (Z).

14. Biomechanics In coxa vara , with a progressive decrease in the femoral neck–shaft angle the physis changes its position from horizontal to vertical, thereby becoming increasingly inclined relative to force R shearing force (S) across the physis gradually increases upper femoral epiphysis tends to tilt and become displaced medially tensile stresses (Z) increase Growth of the femoral neck is less on the medial side than on the lateral side.

15. Biomechanics Effects of decrease neck shaft angle the tip of the greater trochanter elevated- Abductor muscle length is shortened position and direction of muscular force (M) are altered point of intersection (X) of muscular force M with the line of action of the partial body weight (K) lowered resultant compressive force R diverges more than normal in coxa vara - Increase shearing force

16. Biomechanics Effects of shortened femoral neck The length of the lever arm (h) of the muscular force (M) is diminished In response to efforts to preserve equilibrium, the muscle forces and resultant compressive forces (R) increase Therefore, shortening of the femoral neck increases bending stress

17. Developmental Coxa Vara Clinical Features - does not manifest until after birth and usually not until walking age -painless limp -Easy fatigability or aching pain around the gluteal muscles - bilateral involvement: waddling gait

18. Developmental Coxa Vara On Examination - Limitation of abduction and internal rotation - Trendelenburg test positive -Shortening in unilateral cases ( seldom exceeds 3 cm at skeletal maturity, even in untreated patients )

19. Developmental Coxa Vara Radiographic Findings - decreased neck–shaft angle of the affected hip -widened radiolucent line corresponding to the proximal femoral physis -relative overgrowth of the greater trochanter -shortening of the femoral neck -vertical orientation of thecapital physis - inverted “V” Sign

20. Developmental Coxa Vara Quantification of Varus deformity 1.Neck-Shaft angle 2.Head-Shaft angle 3.Helgenreiner-Epiphyseal angle(H-E angle)

21. Developmental Coxa Vara Helgenreiner - Epiphyseal angle(H-E angle) Normal : 0-25 degree( Avg 16 degree) prognostic value of the H-E angle > 60 degrees : deformity invariably progress and merit surgical correct <45 degrees: stable or improves 45 and 59 degrees: indeterminate

22. Developmental Coxa Vara Treatment Goals of treatment - stimulate ossification and healing of the defective femoral neck -restore the femoral head–shaft angle to normal - restore normal mechanical muscle function to the hip abductors

23. Developmental Coxa Vara Modality of treatment CORRECTIVE VALGUS OSTEOTOMIES Valgus osteotomy of the upper femur at the intertrochanteric or subtrochanteric level is the most effective way to correct the varus deformity, - to rotate the proximal femoral physis from a vertical to horizontal position (relieving shear stress on it), - to enhance ossification of the defect

24. Developmental Coxa Vara Indications of Surgery - H-E angle of 60 degrees or greater -Neck shaft angle less than 110 degree -symptomatic limp - Trendelenburg gait -progressive deformity

25. Developmental Coxa Vara Timing of Surgery as soon as bony development is deemed adequate by the treating surgeon to allow secure fixation of the surgeon's preference(Usually 4-5 yrs)

26. Developmental Coxa Vara Fixation options Steinmann pins to the proximal and distal fragments incorporated in plaster transfixing crossed Steinmann pins external fixation with monolateral half-pin fixators hybrid circular external fixation with wires and half-pins bifid plates (as described in Muller, Allgower , and Willenegger ) vitallium mold arthroplasty for degenerative disease standard blade plates dynamic hip compression plates

27. Developmental Coxa Vara Amount of valgus correction -plays an important role in the recurrence of deformity with growth, which has been estimated to occur in 30% - 70% of cases “A postoperative HE angle of 35 degrees or less and a HS angle of 130 degrees or more was correlated with consistently satisfactory results” “if Hilgenreiner's epiphyseal angle was corrected to < 38 degrees, 95% of children had no recurrence of varus ”.

28. Developmental Coxa Vara PAUWEL’S VALGUS OSTEOTOMY - more complex osteotomy -cuneiform Y-shaped intertrochanteric osteotomy objective -to place the capital femoral physis perpendicular to the resultant compressive force and to decrease the bending stress in the femoral neck

29. Developmental Coxa Vara PAUWEL’S VALGUS OSTEOTOMY Preoperative planning horizontal line (H) 4 to 6 cm below the lesser trochanter line (Ps, corresponding to the epiphyseal line) is drawn From the point of intersection of the lines H and Ps, a third line is drawn inclined upward 16 degrees from the horizontal The angle formed between the third line (inclined upward) and the line Ps is the size of the wedge to be resected

30. Developmental Coxa Vara PAUWEL’S VALGUS OSTEOTOMY Wedge Resected upper line of the intertrochanteric osteotomy

31. PAUWEL’S VALGUS OSTEOTOMY

32. PAUWEL’S VALGUS OSTEOTOMY

33. Developmental Coxa Vara BORDEN AND COLLEAGUES guidewire is inserted into the center of the superior half of the femoral neck parallel to its upper border the blade of a blade plate of appropriate size with an angle of 140 degrees is inserted into the neck parallel to the long axis of the femoral neck.

34. Developmental Coxa Vara BORDEN AND COLLEAGUES… An intertrochanteric transverse osteotomy made at level o2 to 2.5 cm distal to the angle of the blade head and neck of the femur are adducted by using the blade as a lever, and the femoral shaft is abducted . lateral cortex of the upper fragment is thus approximated to the upper end of the lower fragment. Adducted Abducted

35. Developmental Coxa Vara WAGNER FIXATION performed with a bifurcated plate driven through the intramedullary surface of the proximal fragment and secured to the distal fragment with screws

36. SUBTROCHANTRIC VALGUS OSTEOTOMY A closing wedge osteotomy just distal to the greater trochanter pediatric lag screw with a side plate or proximal femoral locking plate for internal fixation the amount of valgus necessary to align the hip properly is determined preoperatively by comparing radiographs with those of the contralateral hip.

37. SUBTROCHANTRIC VALGUS OSTEOTOMY the length of the femoral head and neck fragment does not change only the angles and the leg length change amount of change in leg length can be computed by determining the change in the two angles change in leg length (ΔH) is equal to the length of the point from the middle of the osteotomy site to the middle of the femoral head (L) times the cosine of one angle minus the cosine of the new angle: H = L(cos @ 1 − cos @ )

38. SUBTROCHANTRIC VALGUS OSTEOTOMY

39. SUBTROCHANTRIC VALGUS OSTEOTOMY When the angle of correction is determined, the appropriate laterally based closing wedge osteotomy can be determined First determine the diameter of the bone by drilling a guide pin transversely through the femur Determine the correct size of the wedge by using a template, tangent tables ( W = tangent of the angle × the diameter), or the formula W = 0.02 × diameter × angle. Outline the appropriate closing wedge osteotomy in the subtrochanteric area .

40. SUBTROCHANTRIC VALGUS OSTEOTOMY After Treatment: A spica cast can be worn until union is Complete Cast can be removed at 8-12 wks

41. Complications 1. Recurrence Regardless of method of osteotomy the deformity can recur recurrence ranges from 30- 70%. children should be examined periodically after surgery; until their growth is complete

42. Complications 2. Development of Coxa Valga more frequently seen complication of the intertrochanteric osteotomy procedure attributed to injury of the greater trochanteric apophysis , resulting in premature growth arrest continued growth of the capital epiphysis after healing of cervical defect without the normal restraining influence of the greater trochanteric apophysis

43. Complications 3. Premature epiphyseal plate closure It has not been documented to relate to surgical trauma, patient age or degree of valgus osteotomy correction more likely it represents a possible surgically induced acceleration of natural epiphyseal plate closure 50% to 89% of operated hips demonstrate premature closure of the proximal femoral epiphyseal plate usually occurs within 12 to 24 months of surgery

44. Complications 4. Avascular necrosis reported in osteotomies above the level of the greater trochanter attributed to abnormal sublaxation of the femoral head or impairment of the vascular supply of the femoral head.

45. Complications 5. Degenerative changes degenerative changes in developmental coxa vara appear in upto 28.5 % of the patients. develop late (after the age of 30-40 years) and in 15.8% of patients they are mild, in 12.6 % of patients they reach a considerable degree.

46. Complications Other complications LLD Pseudoarthrosis Trochantric overgrowth

47. Take home message Clinical evaluation at infancy/childhood to identify coxa vara early and timely intervention as per degree of severity Non surgical interventions has got greater degree of failure and asso.complications Surgery can be delayed until the child 4-5yrs old to make internal fixation easier

48. Take home message currently, the most effective surgical treatment is a valgus producing proximal femoral osteotomy ( subtrochanteric and intertrochanteric procedures have similar results) Postoperative followup is adviced in children until epiphyseal fusion is complete till adult age group

49. THANK YOU