Introduction: This study examined the outcomes of applying transtrochanteric rotational osteotomy (TRO) for posttraumatic osteonecrosis of the femoral head (ON).
Patients and methods: We retrospectively reviewed 28 hips in 28 patients (male, n = 17; female n = 11) with a mean age of 34.8 years (12-61 years) at the time of TRO. Transtrochanteric anterior rotational osteotomy (ARO) was used when the lesion was localized on the anterior aspect of the femoral head, and transtrochanteric posterior rotational osteotomy (PRO) was indicated in patients with lesions limited to the posterior aspect of the femoral head. The mean follow-up period was 12.3 years (5.0-21.3 years). We investigated the patients' clinical and radiological factors, including age, sex, body mass index, preoperative Harris Hip Score (HHS), type of antecedent trauma, preoperative stage, and postoperative intact ratio (the ratio of the intact articular surface of the femoral head to the weight-bearing surface of the acetabulum). We divided the patients into a hip-survival group and a conversion-to-total hip arthroplasty (THA) group and then compared these factors between the two groups.
Results: At the final follow-up, 22 hips had survived with a mean HHS of 85.8. The remaining six hips underwent THA at a mean of 10.2 years after TRO. The preoperative stage was correlated with hip survival. Furthermore, the postoperative intact ratio was significantly lower in the conversion-to-THA group. Based on the receiver operating characteristic curve, a ratio of less than 33.6 % was found to be associated with the need to convert to THA.
Conclusions: TRO to correct posttraumatic ON resulted in favorable midterm results. The possible risk factors for conversion to THA were an advanced preoperative stage and a postoperative intact ratio of less than 33.6 %.