- Deformity of the hip in which the angle between the head and shaft of the femur is reduced to less than 120o
- Associated with an ossification defect in inferior femoral neck
Epidemiology
- Males and females affected equally
- 1/3 cases are bilateral
Etiology
- Developmental
- Congenital – congenital short femur
- Acquired – SCFE , infection, Perthes Disease
- Dysplasia – Osteogenesis imperfecta , Jansen
- Cretinism
Pathophysiology
- There is abnormal development of the proximal femoral growth plate (physis) and defective ossification of the adjacent metaphysis
- Results in progressive decrease of the neck-shaft angle
- The proximal femoral physis is in a vertical position
- Can lead to increased physeal shearing forces
Clinical features
- Usually painless
- Gait abnormality – waddling/limp (Trendelenburg gait)
- Due to abductor weakness from tension abnormality
Diagnosis
History
- Previous hip trauma or infection
- Associated skeletal abnormalities
- Prenatal and developmental history
- Family history of similar deformity
Physical exam
- Leg length discrepancy
- High riding greater trochanter
- Limb shortening
- Excessive lumbar lordosis
- Restricted range of motion in hip (painless)
X-ray
- The neck-shaft angle <120o
- Vertical physis
- Increased Hilgenreiner’s epiphyseal angle (HEA) – normal is <25o
CT – for surgical planning
Treatment
- Observation
- If HEA is 45-60o
- Operative – valgus derotation osteotomy (VDRO)
- If HEA is >60o
- Aims to correct neck-shaft angle, leg length discrepancy and abductor weakness
- Requires post-operative hip-spica casting