Bilaterality in slipped upper femoral epiphysis.

The frequency of slipping and osteoarthritis of the contralateral hip was recorded in 260 patients with slipped upper femoral epiphysis between 1910 and 1960. Twenty-three of these patients (9%) had primary bilateral slipping, 32 (12%) had a contralateral slip diagnosed later during adolescence and a further 104 (40%) had signs of contralateral slipping at follow-up 16 to 66 years later, giving a total of 159 cases (61%) with bilateral slips. Of the 104 slippings diagnosed at follow-up, 25% showed osteoarthritis. It is concluded that, with a slipped epiphysis, prophylactic contralateral pinning should be performed to avoid slipping and to reduce the risk of osteoarthritis.