Pain in the hip and knee

Childhood

A child with hip disease may not present with pain or a history of trauma but with an unexplained limp. Unexplained knee pain should raise the suspicion of hip abnormality.

Congenital dislocation of the hip—Ultrasound screening should detect children at risk, but missed cases may present with a delay in walking, limp, or discrepancy in leg length. Children usually present before the age of 5 years. Missed diagnosis can lead to a non-congruent joint and early osteoarthritic degeneration in adulthood.

Perthes' disease—Disintegration of the femoral head, with subsequent healing and deformity of the hip, usually occurs in boys aged 5-10 years. The precise cause is unclear, but segmental avascular necrosis of the femoral head is probably responsible. A limp, hip pain, or knee pain may result. Treatment aims to contain the femoral head in the acetabulum to reduce the risks of future osteoarthritis.

Anteroposterior radiograph of child with dislocated right hip. Note the lateral displacement of the femur and the poorly developed ossific nucleus of the hip

Slipped upper femoral epiphysis is typically seen in overweight, hypogonadal boys, who often present with pain referred to the knee, although girls can also be affected. Diagnosis can be difficult, but a “frog lateral” radiograph will show the deformity. Surgical stabilisation is needed urgently to prevent further slippage of the epiphysis. The contralateral hip is at high risk of slippage, and patients and parents should be warned to return if any knee or hip pain occurs.

Septic arthritis is relatively uncommon, but it should be suspected in a child who is ill, toxic, and unable to walk. Pain prevents movement of the affected joint. Diagnosis is confirmed by raised white cell count and erythrocyte sedimentation rate and perhaps by effusion on ultrasound images. Urgent surgical drainage is vital to reduce the …