Between 1972 and 1979, 128 patients with idiopathic ONFH underwent osteotomy in our department. Fifteen hips of 9 patients, who had been visiting our outpatient office and had their living hip joints more than 25 years after operation, were examined. The hips were separated into two groups (Table 1). One group includes the hips that had advanced or terminal osteoarthritis (OA) at the last follow-up. Another group includes those that had no OA or early OA. Age at operation and period after operation were similar in both the groups. Clinical scores were assessed according to the hip scoring system by the Japanese Orthopaedic Association.
Table 1. Characterization of the hips in two groups
With advanced OA
Without advanced OA
Number of examined hips Age at operation (years) Involved in the contralateral side Period after operation (years) Stage
JOA scorea at the last follow-up
OA, osteoarthritis a In the clinical scoring system for hip joints developed by the Japanese Orthopaedic Association, the maximum score is 100 points
All hips that had no or early OA at the last follow-up were at stage 3A at operation and had no collapse progression after osteotomy (see Table 1). The average of their clinical scores was promising. In contrast, approximately half of the hips that had advanced or terminal OA at the last follow-up were at stage 3B at operation. Furthermore, all of them had collapse progression and had poor clinical scores at the last follow-up.
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