COXA VARA AND COXA VALGA, DEVLOPMENTAL COXA VARA.pptx

COXA VARA AND VALGA, HIP BIOMECHANICS, DEVELOPMENTAL COXA VARA

1. COXA VARA AND COXA VALGA PRESENTER: DR. KISAN NEPALI

2. Content Introduction Development of neck shaft angle Related biomechanics Biomechanics changes in coxa valga and coxa vara Coxa valga Coxa vara Developmental coxa vara

3. Introduction: Neck shaft angle Varies according to age. Freedom of motion. Deviation in either ways alter force relationship and biomechanics of hip joint. Understanding balance of force and moments to estimate effects of alteration.

4. Development of Neck shaft angle Crescentic cartilage column Trochanteric epiphysis Greater Trochanter Cervical epiphysis Neck and head

5. Progressive weight bearing Muscular force Fig: development of Neck shaft angle

6. In adult , NSA: 120 Range: 115-140 Decrease in Neck shaft angle below normal: Coxa Vara Increase in Neck shaft angle above normal: Coxa Valga

7. Biomechanics Effort Load Fulcrum: Hip joint Abductor tension Body weight Resultant joint force Effort X Effort arm= load X Load arm

8. W= 2/3 OF TBW W= 1/3 OF TBW W= 1/3 OF TBW LL= (1/6+1/6) OF TBW =2/6 OF TBW =1/3 OF TBW DOUBLE LEG STANCE

9. 3W W ---X--- -------3X------- Effort X Effort arm= load X Load arm SINGLE LEG STANCE

10. Effect of NSA on loading Ref: Biomechanics of normal and diseased hip

11. Effect of NSA on stress on proximal femur Ref: Biomechanics of normal and diseased hip

12. Effect of neck length on proximal femur Ref: Biomechanics of normal and diseased hip

13. Articular congruency Ref: Biomechanics of normal and diseased hip

14. Summary Coxa vara reduces the load supported by the hip joint and the upper end of the femur, but greatly increases the stressing of the femoral neck. Inversely, coxa valga augments the load supported by the hip and neck but reduce the stressing of the femoral neck. Stressed in pure compression and either slightly or not at all in shearing.

15. Coxa valga Infants valgus to varus ( 148 to 120) under the influence of the abductor force and walking. Most of this correction actually occurs by the time children are 2 to 3 years of age. The direct cause of the coxa valga is the abnormal force on the proximal femoral growth plate.

16. Causes of coxa valga Bilateral Neuromuscular disorders, e.g. cerebral palsy often have concurrent femoral anteversion Skeletal dysplasias , e.g. Turner syndrome, mucopolysaccharidoses Medical condition: Rickets Unilateral Trauma causing growth plate arrest

17. Clinical feature Generally asymptomatic in infants. Older kids and adult: Pain Limit mobility of hip LL discrepancy Walking difficulty

18. Treatment In many cases, is a symptom of another medical condition. No need of treatment as long as acetabulum shows adequate development When required, Varus derotation osteotomy and angled blade-plate fixation is effective. Osteotomy is done at intertrochanteric or subtrochanteric level .

19. Coxa vara: Classification CONGENITAL FEMORAL DEFICIENCY WITH COXA VARA DEVELOPMENTAL COXA VARA Isolated (may be bilateral) Associated with a skeletal dysplasia Cleidocranial dysostosis Metaphyseal dysostosis Other skeletal dysplasias . ACQUIRED COXA VARA Slipped capital femoral epiphysis Sequela of avascular necrosis of the femoral epiphysis Legg- Calvé -Perthes disease Traumatic coxa vara Femoral neck fracture Traumatic hip dislocation Sequela of reduction for developmental dysplasia of the hip Septic necrosis 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

20. Congenital Coxa Vara Present at birth Extremely rare a/w: Proximal femoral focal deficiency Fibular hemimelia Anomalies in other part of body: cleidocrainal dysostosis

21. Developmental Coxa Vara Often B/L progressive decrease in the femoral neck shaft angle shortening of the affected lower limb Presence of defect in the medial part of the neck

22. Epidemiology Incidence: 1: 25000 live birth in Scandinavian population M:F=1:1 Unilateral to bilateral cases in between 1:2 and 3:1 Bilateral cases more likely to be a/w a generalized skeletal dysplasia

23. Pathoanatomy Primary defect in endochondral ossification of the medial part of the femoral neck. Dystrophic bone along medial inferior aspect of femoral neck. Fatigues with weight bearing Progressive varus deformity.

24. Pathoanatomy Studies reports Defects in cartilage production and secondary metaphyseal bone formation Cartilage cell no. reduced Not well organized in regular column Adjacent metaphyseal bone osteoporotic and infiltrated with nest of cartilage cells. Acetabulum: decreased volume Femoral head: small Femoral neck: shorter Physis: wider

25. Biomechanics

26. Compression and tensile force in normal and abnormal hip

27. Effects of decrease neck shaft angle

28. Effect of shortened femoral neck

29. Clinical Features Does not manifest until after birth and usually not until walking age Painless limp Abductor weakness LL discrepancy Painless but easy fatigability or aching pain around the gluteal muscles after prolonged exercise Trendelenberg gait, B/L: waddling gait.

30. On examination: GT more prominent and proximal Limitation of abduction and internal rotation Trendelenburg test positive Shortening in u/l cases (seldom exceeds 3cm at skeletal maturity, even in untreated patients) Evidence of skeletal dysplasia

31. Radiographic findings: Decreased NSA of the affected hip More vertical orientation of physeal plate Short neck Abnormal bony fragment inferolateral to the physeal plate and contained in inverted Y shaped lucency Acetabular dysplasia

32. Quantification of varus deformity Neck –shaft angle Head shaft angle Helgenreiner -Epiphyseal angle (H-E angle)

33. Helgenreiner – Epiphyseal angel (H-E) angle Normal : 0-25 (avg: 16) Prognostic value of H-E angle >60 degree: deformity invariably progress and need surgical correction. <45 degree: stable or improves 45 and 59 degree : indeterminate

34. Natural history Increase tensile force on superior femoral neck Progressive varus deformity Stress-fracture related non union of femoral neck Premature degenerative arthritis changes Does is occur in all cases? Weinstein et al. Determining factor H-E angle (60,60-45,45)

35. Treatment No cause- no cure Aimed at preventing secondary deformities. Goals of treatment Correction of the varus angulation into a more normal physiological range Changing the loading characteristics seen by femoral from shear to compression Correction of limb length inequality Reestablishment of a proper abductor muscle length-tension relation.

36. Nonsurgical H-E angle of <45 degree and are asymptomatic Assess for evidence of skeletal dysplasia LL inequality Periodic radiographic assessment to assess deformity till maturity. HE angle between 45-60 degree Serial radiographs to assess for progression For symptomatic limp, Trendelenburg gait, or progressive deformity surgery is done.

37. Operative Indication of surgery HE angle of 60 degree or greater Neck shaft angle less than 110 degree Symptomatic limp Trendelenburg gait Progressive deformity

38. Surgery Corrective valgus osteotomies intertrochanteric or subtrochanteric level To rotate the proximal femoral physis from a vertical to horizontal position (convert shear force into compressive force) To allow remodeling and normal ossification to occur Restore hip abductor function.

39. Timing of surgery Two problem Early: weak fixation Late : acetabular dysplasia become permanent As soon as bony development is deemed adequate (usually 4-5 years)

40. Osteotomy Intertrochanteric osteotomy Langenskiold Valgus producing osteotomy Pauwel osteotomy Subtrochanteric osteotomy Borden Osteotomy

41. Pawel’s valgus osteotomy Cuneiform Y-shaped intertrochanteric osteotomy

42. Borden and colleagues The blade of a blade plate of appropriate size with an angle of 140 degree is inserted into the neck parallel to the long axis of the femoral neck.

43. Wagner fixation Performed with a bifurcated plate driven through the intramedullary surface of the proximal fragment and secured to the distal fragment with screws.

44. After treatment : A spica cast can be worn until union is complete. Cast can be removed at 8-12 wks Implant removal after 1-2 years following healing of osteotomy

45. Complication: Recurrence 30-70% Development of coxa valga Mc: intertrochanteric osteotomy Premature epiphyseal plate closure Avascular necrosis Degenerative changes Others: LLD, Pseudoarthrosis, trochanteric overgrowth.

46. Summary NSA is very crucial for facilitating hip ROM. Any deviation has severe impact on hip biomechanics . Developmental coxa vara has characteristic clinical and radiological finding . The first step in treating development coxa vara is to find out any other possible cause for this condition(Table) Once diagnosed, child follow up every 4 to 6 month and radiograph evaluated for H-E angle , symptomatic limp or Trendelenburg gait. Valgus producing osteotomy with appropriate rotational osteotomy is preferred treatment.

47. References Biomechanics of normal and diseased hip Campbell’s operative orthopedics, 14th edition Tachdjian's Pediatric Orthopaedics 6th Ed lovell and winter's pediatric orthopedics 8th edition Related article Internet

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