Department of Orthopaedics and Trauma, Level 4, Bice Building, North Terrace, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.
J Bone Joint Surg Am. 2012 Jun 20;94(12):1095-102. doi: 10.2106/JBJS.K.00570.
The use of larger femoral heads has been proposed to reduce the risk of dislocation after total hip arthroplasty, but there is a lack of evidence to support this proposal. The aim of this multicenter randomized controlled trial was to determine whether the incidence of dislocation one year after total hip arthroplasty is significantly lower in association with the use of a 36-mm femoral head articulation as compared with a 28-mm articulation.
Six hundred and forty-four middle-aged and elderly patients undergoing primary or revision arthroplasty were randomized intraoperatively to receive either a 36 or 28-mm metal femoral head on highly cross-linked polyethylene. Patients who were at high risk of dislocation (including those with dementia and neuromuscular disease) and those undergoing revision for the treatment of recurrent hip dislocation or infection were excluded. Patients were stratified according to other potential risk factors for dislocation, including diagnosis and age. Diagnosis of hip dislocation required confirmation by a physician and radiographic evidence of a dislocation.
Overall, at one year of follow-up, hips with a 36-mm femoral head articulation had a significantly lower incidence of dislocation than did those with a 28-mm articulation (1.3% [four of 299] compared with 5.4% [seventeen of 316]; difference, 4.1% [95% confidence interval, 1.2% to 7.2%]) when controlling for the type of procedure (primary or revision) (p = 0.012). The incidence of dislocation following primary arthroplasty was also significantly lower for hips with a 36-mm femoral head articulation than for those with a 28-mm articulation (0.8% [two of 258] compared with 4.4% [twelve of 275]; difference, 3.6% [95% confidence interval, 0.9% to 6.8%]) (p = 0.024). The incidence of dislocation following revision arthroplasty was 4.9% (two of forty-one) for hips with a 36-mm articulation and 12.2% (five of forty-one) for hips with a 28-mm articulation; this difference was not significant with the relatively small sample size of the revision group (difference, 7.3% [95% confidence interval, -5.9% to 21.1%]) (p = 0.273).
Compared with a 28-mm femoral head articulation, a larger 36-mm articulation resulted in a significantly decreased incidence of dislocation in the first year following primary total hip arthroplasty. However, before a 36-mm metal-on-highly cross-linked polyethylene articulation is widely recommended, the incidence of late dislocation, wear, periprosthetic osteolysis, and liner fracture should be established.
人们提出使用更大的股骨头来降低全髋关节置换术后脱位的风险，但目前缺乏支持这一建议的证据。本多中心随机对照试验的目的是确定在全髋关节置换术后 1 年，使用 36mm 股骨头关节与使用 28mm 关节相比，脱位的发生率是否显著降低。
644 名接受初次或翻修关节置换术的中老年患者在术中被随机分为使用高交联聚乙烯的 36mm 或 28mm 金属股骨头。排除脱位风险高的患者（包括痴呆和神经肌肉疾病患者）和因复发性髋关节脱位或感染而接受翻修的患者。根据其他潜在脱位危险因素（包括诊断和年龄）对患者进行分层。髋关节脱位的诊断需要医生确认和影像学证实脱位。
在 1 年的随访中，控制手术类型（初次或翻修）后，使用 36mm 股骨头关节的髋关节脱位发生率明显低于使用 28mm 关节的髋关节（1.3%[299 例中的 4 例]比 5.4%[316 例中的 17 例]；差异为 4.1%[95%置信区间，1.2%至 7.2%]）（p = 0.012）。初次关节置换术后使用 36mm 股骨头关节的髋关节脱位发生率也明显低于使用 28mm 关节的髋关节（0.8%[258 例中的 2 例]比 4.4%[275 例中的 12 例]；差异为 3.6%[95%置信区间，0.9%至 6.8%]）（p = 0.024）。使用 36mm 关节的髋关节翻修后脱位发生率为 4.9%（41 例中的 2 例），使用 28mm 关节的髋关节翻修后脱位发生率为 12.2%（41 例中的 5 例）；但由于翻修组的样本量相对较小，差异无统计学意义（差异为 7.3%[95%置信区间，-5.9%至 21.1%]）（p = 0.273）。
与 28mm 股骨头关节相比，在初次全髋关节置换术后的第一年，较大的 36mm 关节可显著降低脱位的发生率。然而，在广泛推荐使用 36mm 金属-高交联聚乙烯关节之前，应确定晚期脱位、磨损、假体周围骨溶解和衬垫骨折的发生率。
