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Coxa Vara

Elaine Tran, PGY-4

7/24/2017

Overview

Introduction

Classification and Etiology

Pathophysiology

Biomechanics

Patient Evaluation

Treatment

Introduction

Definition

Incidence

Introduction

Definition

Definition

  • Neck Shaft Angle- 120-135 degrees

  • Coxa Vara
  • Abnormal decrease in femoral neck-shaft angle

Incidence

Incidence

  • 1:25,000 live births
  • M = F
  • No racial predilection
  • Bilateral- 30-50%
  • Generalized skeletal dysplasia

Classification and Etiology

Classification

Subtypes

  • Developmental
  • + Dysplasia
  • Acquired
  • Congenital Femoral Deficiency

Genetic Association

Classification

Classification

  • (1) Developmental
  • Congenital
  • Cervical
  • Infantile

  • (2) Acquired

  • (3) Congenital Femoral Deficiency w/ Coxa Vara

Classification

  • Anatomic Site
  • Physis
  • Trochanteric
  • Subtrochanteric
  • Clinical
  • Developmental
  • Congenital
  • Dysplastic
  • Traumatic

Developmental

Developmental

  • "Congenital" or "Infantile"
  • At the physis
  • +/- Skeletal dysplasia
  • Progression is common
  • Biomechanical stress on physis
  • Need to monitor
  • Radiographs
  • Dense triangular portion of femoral calcar

Developmental + Dysplasia

  • Most are metaphyseal
  • Progressive
  • Symmetric delay of ossification
  • Prognosis varies

  • Examples
  • Jansen, Schmid, Strudwick
  • Spondylometaphyseal dysplasia
  • Spondyloepiphyseal dysplasia
  • Cleidocranial dysplasia

Acquired- Traumatic

  • Perinatal epiphyseal separation
  • Fracture or osteotomy
  • Physeal sepsis/Trochanteric overgrowth
  • Vascular injury to physis/Trochanteric overgrowth

Impaired Growth of Capital Femoral Physis

Acquired- Pathologic Bone

  • Disease
  • Vitamin D resistant rickets
  • Fibrous dyspasia
  • Paget's disease
  • Osteopetrosis

  • Characteristics
  • Subtrochanteric Region
  • Bowing of Femur

Congenital Femoral Deficiency

  • Congenitally short femur
  • Percentage is constant
  • Usually unilateral
  • Deformity in the subtrochanteric region
  • Thickened cortices
  • Overlying skin dimple
  • Femoral retroversion and valgus knee
  • Other associated skeletal anomalies
  • Fibular deficiency

Genetics

Genetics

  • Skeletal Dysplasias- Autosomal Dominant
  • Cleidocranial dysostosis
  • Metaphyseal dysostosis
  • Jansen Type
  • Spondylometaphyseal dysplasia

  • Isolated Developmental
  • Homozygous and heterozygous twins

Pathophysiology

Normal Development

Coxa Vara

Pathophysiology

Normal Development

Normal Development

  • Ossification Centers

  • Femoral anteversion 10-15 degrees

  • Neck shaft angle- 120-135 degrees

Femoral Anteversion

Cervicofemoral Angle

  • Common Physis
  • Captial Femoral Epiphysis
  • Greater Trochanter

  • Cervicofemoral angle
  • Infancy- 35 degrees
  • Skeletal maturity- 45 degrees
  • Coxa vara- increase angle

Neck Shaft Angle

Coxa Vara

Coxa Vara

  • Anatomic descriptions
  • Fibrous tissue @ medial metaphysis of femoral neck
  • Mechanically weak femoral neck--> deformed into varus angulation

  • Histologic descriptions
  • Disorganized, decreased cartilage
  • Decreased bloody supply
  • Absent bony trabecular network in medial neck

Biomechanics

Normal force across the hip

Increasing Shear Force

Elevation of Greater trochanter

Shortened Femoral Neck

Biomechanics

Normal Force across the Hip

Normal Force across the Hip

Increase Shear Force

Elevation of Greater Trochanter

Shortened Femoral Neck

Patient Evaluation

Clinical Presentation

Imaging

Patient Evaluation

Clinical Presentation

Clinical Presentation

  • Manifest after walking age
  • Painless limp
  • Fatigability or aching pain
  • PE
  • Decreased AB, IR
  • + Trendelenburg
  • LLD (< 3 cm)
  • Skeletal dysplasia

Imaging

Imaging

  • Plain radiographs
  • AP
  • Neck-shaft angle
  • Widened proximal femoral physis
  • Inverted V
  • Acetabular dysplasia

  • Lateral
  • Femoral anteversion
  • CT

Inverted V/Y

Hilgenreiner-Epiphyseal Angle

Weinstein et al. 1984

  • Normal- 0-25
  • average 16
  • < 45 degrees--> stable/improved
  • 45-60 degrees--> indeterminate
  • > 60 degrees--> progress

Treatment

Goals

Indications for surgery

Valgus Osteotomy

Complications

Goals of Surgery

Goals of Surgery

  • Stimulate ossification and healing
  • Over-correct neck shaft angle
  • Correct LLD
  • Correct hip anteversion/retroversion
  • Restore mechanics of abductors

Indications for Surgery

Indications for Surgery

  • Symptoms
  • Limp
  • Trendelenburg gait
  • Severity of deformity
  • H-E angle > 60 degrees
  • Chondrodysplasia syndrome
  • High rates of recurrence
  • Poor functional outcome after valgus correction

H-E Angle < 45

  • Observation and Monitoring
  • Asymptomatic
  • Assess for LLD (if unilateral)
  • Minor
  • Shoe lift
  • Contralateral epiphysiodesis

H-E Angle 45-59

  • Observation and monitoring
  • Surgical intervention
  • Symptomatic
  • Progressive deformity

H-E angle > 60- Valgus Osteotomy

H-E angle > 60- Valgus Osteotomy

  • Young Patients w/ severe deformity
  • Timing--> bone development for fixation
  • Techniques
  • Steinmann pins
  • Ex-fix
  • Bifid plates
  • Blade plates
  • Dynamic hip compression plates

Recurrence of Deformity

  • Recurrence rate 30-70%

  • Caroll et al. 1997
  • H-E < 38--> 95% success rate
  • Overal recurrence- 50%
  • Cordes et al. 1991
  • H-E < 40 @ 11 yrs f/u
  • Desai et al. 1993
  • H-E < 35 and Neck-shaft angle < 130 @ 20 yrs

Valgus Osteotomy

Cuneiform Y-Shaped IT Osteotomy

Complications

Complications

  • Loss of correction
  • Premature closure of proximal femoral physis
  • Overgrowth of proximal femur
  • Dysplasia of acetabulum

Summary

Summary

  • Decrease in neck-shaft angle or increase in H-E angle
  • Eval for skeletal dysplasia
  • Surgical considerations- symptoms and H-E angle
  • Monitor for H-E angle < 59
  • Valgus osteotomy for H-E angle < 60
  • Obtain adequate correction to decrease rate of recurrence

References

Thank you!

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