Degenerative osteoarthritis after Perthes' disease: a 36-year follow-up.

Background: Although the prognosis of Perthes' disease at skeletal maturity is considered favorable, little is known about the long-term results after middle age.

Methods: We retrospectively analyzed the radiographic and functional outcomes of 67 patients (70 hips) who had been treated for Perthes' disease. Of these patients, 28 patients (29 hips) were evaluated using JOA (Japanese Orthopaedic Association) score and radiographs at follow-up (Group 1), 39 patients (41 hips) were evaluated by a postal questionnaire (Group 2). The mean follow-up period was 36.1 years. The mean age at follow-up was 43.1 years.

Results: Group 1, good radiographic results (Stulberg class I or II) were achieved in 59% of hips. No osteoarthritis (Tönnis Grade 0) was observed in only 48% of hips. The clinical results were good (JOA score ≥ 70) in 79% of hips. Disturbance of walking ability and activities of daily living was little. The Tönnis grade and JOA score declined after 40 years of age. All patients older than 50 years showed severe osteoarthritis. The severity of osteoarthritis correlated significantly with age at follow-up. Group 2, the clinical results were good (JOA score ≥ 56) in 76% of hips. In both groups, no patient had undergone total hip arthroplasty. Younger age at diagnosis (<8 years) correlated significantly with a better result. The JOA score correlated significantly with age at follow-up.

Conclusion: Patients who were treated for Perthes' disease have a risk of osteoarthritis and a clinically poor outcome after the age of 40-50 years.