Coxa Vara
Elaine Tran, PGY-4
7/24/2017
Overview
Introduction
Classification and Etiology
Pathophysiology
Biomechanics
Patient Evaluation
Treatment
Definition
- Neck Shaft Angle- 120-135 degrees
- Coxa Vara
- Abnormal decrease in femoral neck-shaft angle
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
- (1) Developmental
- Congenital
- Cervical
- Infantile
- (3) Congenital Femoral Deficiency w/ Coxa Vara
Classification
- Anatomic Site
- Physis
- Trochanteric
- Subtrochanteric
- Clinical
- Developmental
- Congenital
- Dysplastic
- Traumatic
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
- 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
- Femoral anteversion 10-15 degrees
- Neck shaft angle- 120-135 degrees
Cervicofemoral Angle
- Common Physis
- Captial Femoral Epiphysis
- Greater Trochanter
- Cervicofemoral angle
- Infancy- 35 degrees
- Skeletal maturity- 45 degrees
- Coxa vara- increase angle
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
Elevation of Greater Trochanter
Patient Evaluation
Clinical Presentation
Imaging
Patient Evaluation
Clinical Presentation
- Manifest after walking age
- Painless limp
- Fatigability or aching pain
- PE
- Decreased AB, IR
- + Trendelenburg
- LLD (< 3 cm)
- Skeletal dysplasia
Imaging
- Plain radiographs
- AP
- Neck-shaft angle
- Widened proximal femoral physis
- Inverted V
- Acetabular dysplasia
- Lateral
- Femoral anteversion
- CT
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
- Stimulate ossification and healing
- Over-correct neck shaft angle
- Correct LLD
- Correct hip anteversion/retroversion
- Restore mechanics of abductors
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
- 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
Cuneiform Y-Shaped IT Osteotomy
Complications
- Loss of correction
- Premature closure of proximal femoral physis
- Overgrowth of proximal femur
- Dysplasia of acetabulum
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