Evaluation of instability after transtrochanteric anterior rotational osteotomy for nontraumatic osteonecrosis of the femoral head.
BACKGROUND
Transtrochanteric anterior rotational osteotomy results in improvement of joint congruity and prevention of progressive collapse and osteoarthritic changes in patients with femoral head osteonecrosis. However, this procedure remains controversial for patients with extensive collapse due to potential osteoarthritis caused by postoperative instability. The purpose of this study was to evaluate hip instability after osteotomy and determine the relation between instability and radiological and clinical outcomes.


METHODS
In all, 27 hips of 24 patients that were followed up for a mean period of 3.8 years were included. Instability was defined as more than 1 mm translation of the femoral head in transverse computed tomography scans obtained at 0 degrees and 45 degrees flexion of the hip joint. Hips were divided into instability and stability groups.


RESULTS
Eleven hips (40%) developed instability after surgery. Osteophytes on the femoral head in 10 hips of the instability group and 2 hips of the stability group had increased in size at follow-up. There was a significant relation between postoperative instability and osteophyte formation. Joint space narrowing was not seen in any of the cases. There was no significant difference between the groups in either the postoperative intact ratio of the femoral head or the Japanese Orthopaedic Association hip score.


CONCLUSIONS
Neither instability nor osteophyte formation on the femoral head after transtrochanteric anterior rotational osteotomy correlated with progressive osteoarthritic changes or clinical outcome in the presence of an adequate femoral head intact ratio facing the weight-bearing area.
Department of Orthopaedic Surgery, Fujigaoka Hospital, Showa University School of Medicine, Yokohama, Japan.
Yasunari
Y
Hiranuma
Takashi
T
Atsumi
Toshihisa
T
Kajiwara
Satoshi
S
Tamaoki
Yasuhiro
Y
Asakura
D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000601:surgery*; D005271:Femur Head Necrosis / Q000150:complications / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000209:etiology; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000209:etiology; D010027:Osteotomy / Q000009:adverse effects* / Q000379:methods*; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D055815:Young Adult