Haraguchi Naoki, Ota Koki, Tsunoda Naoya, Seike Koji, Kanetake Yoshihiko, Tsutaya Atsushi
Departments of Orthopaedic Surgery (N.H., K.O., N.T., and K.S.) and Radiology (Y.K. and A.T.), Tokyo Metropolitan Police Hospital, 4-22-1 Nakano, Nakanoku, Tokyo 164-8541, Japan. E-mail address for N. Haraguchi:
J Bone Joint Surg Am. 2015 Feb 18;97(4):333-9. doi: 10.2106/JBJS.M.01327.
We determined the preoperative and postoperative passing points of the mechanical axis of the lower limb at the level of the tibial plafond using a new method involving a full-length standing posteroanterior radiograph that includes the calcaneus (a hip-to-calcaneus radiograph) and correlated them to the clinical results after supramalleolar osteotomy for ankle osteoarthritis.
We reviewed the hip-to-calcaneus radiographs of fifty lower limbs of forty-one patients treated for lower limb malalignment at our institution. The mechanical axis point of the ankle was the point at which the mechanical axis divides the coronal length of the plafond, expressed as a percentage. Four independent observers performed all measurements twice. Supramalleolar tibial osteotomy was performed in twenty-seven ankles (twenty-four patients) to treat moderate varus-type osteoarthritis of the ankle. The mean follow-up period was 2.8 years (range, two to 5.3 years). Clinical assessment was based on the American Orthopaedic Foot & Ankle Society (AOFAS) scale.
Interobserver and intraobserver reliability in identifying the mechanical ankle joint axis point were very high. The mean postoperative mechanical axis point was 50% (range, 13% to 70%) in ankles for which the preoperative point was ≤0%, whereas the mean postoperative point was 81% (range, 48% to 113%) in ankles for which the preoperative point was >0%. The mean change in AOFAS score was significantly less for patients with a preoperative point of ≤0% than for those with a preoperative point of >0% (p=0.004). Improvement was significantly greater in ankles with a postoperative mechanical ankle joint axis point of ≥80% than in ankles with a postoperative mechanical ankle joint axis point of <60% (p=0.030).
Traditional tibial correction resulted in great variation in the locations of the postoperative mechanical ankle joint axis point. In ankles with the preoperative point more medial than the tibial plafond, the point was insufficiently moved to the lateral side, and the clinical outcomes were less satisfactory.
我们采用一种新方法，即拍摄包含跟骨的下肢全长站立位正位X线片（髋至跟骨X线片），确定了踝关节平面下肢机械轴的术前和术后通过点，并将其与踝关节骨关节炎行踝上截骨术后的临床结果相关联。
我们回顾了在本机构接受下肢畸形治疗的41例患者50个下肢的髋至跟骨X线片。踝关节的机械轴点是机械轴将胫骨平台冠状长度划分的点，以百分比表示。四名独立观察者对所有测量进行了两次。对27个踝关节（24例患者）行踝上胫骨截骨术，以治疗中度内翻型踝关节骨关节炎。平均随访期为2.8年（范围2至5.3年）。临床评估基于美国矫形足踝协会（AOFAS）评分。
观察者间和观察者内确定机械踝关节轴点的可靠性非常高。术前点≤0%的踝关节术后机械轴点平均为50%（范围13%至70%），而术前点>0%的踝关节术后机械轴点平均为81%（范围48%至113%）。术前点≤0%的患者AOFAS评分的平均变化明显小于术前点>0%的患者（p = 0.004）。术后机械踝关节轴点≥80%的踝关节改善明显大于术后机械踝关节轴点<60%的踝关节（p = 0.030）。
传统的胫骨矫正导致术后机械踝关节轴点位置差异很大。术前点比胫骨平台更靠内侧的踝关节，该点向外侧移动不足，临床结果不太令人满意。
