Research Center, University of Bern, Stauffacherstrasse 78, CH-3014 Bern, Switzerland.
J Bone Joint Surg Am. 2010 Aug 18;92(10):1954-63. doi: 10.2106/JBJS.F.01184.
Studies about the influence of patient characteristics on mechanical failure of cups in total hip replacement have applied different methodologies and revealed inconclusive results. The fixation mode has rarely been investigated. Therefore, we conducted a detailed analysis of the influence of patient characteristics and fixation mode on cup failure risks.
We conducted a case-control study of total hip arthroplasties in 4420 patients to test our hypothesis that patient characteristics of sex, age, weight, body mass index, and diagnosis have different influences on risks for early mechanical failure in cemented and uncemented cups.
Women had significantly reduced odds for failure of cups with cemented fixation (odds ratio = 0.59; 95% confidence interval, 0.43 to 0.83; p = 0.002) and uncemented fixation (odds ratio = 0.63; 95% confidence interval, 0.5 to 0.81; p = 0.0003) compared with that for men (odds ratio = 1). Each additional year of patient age at the time of surgery reduced the failure odds by a factor of 0.98 for both cemented cups (odds ratio = 0.98; 95% confidence interval, 0.96 to 0.99; p = 0.016) and uncemented cups (odds ratio = 0.98; 95% confidence interval, 0.97 to 0.99; p = 0.0002). In patients with cemented cups, the weight group of 73 to 82 kg had significantly lower failure odds (odds ratio = 0.63; 95% confidence interval, 0.4 to 0.98) than the lightest (<64 kg) weight group or the heaviest (>82 kg) weight group (odds ratios = 1.00 and 1.07, respectively). No significant effects of weight were noted in the uncemented group. In contrast, obese patients (a body mass index of >30 kg/m(2)) with uncemented cups had significantly elevated odds relative to patients with a body mass of <25 kg/m(2) (odds ratio = 1.41; 95% confidence interval, 1.03 to 1.91) for early failure of the cups compared with an insignificant effect in the cemented arm of the study. Compared with osteoarthritis as the reference diagnosis (odds ratio = 1), developmental dysplasia (odds ratio = 0.52; 95% confidence interval, 0.28 to 0.97) and hip fracture (odds ratio = 0.38; 95% confidence interval, 0.16 to 0.92) were significantly protective in cemented cups.
Female sex and older age have similarly protective effects on the odds for early failure of cemented and uncemented cups. Although a certain body-weight range has a significant protective effect in cemented cups, the more important finding was the significantly increased risk for failure of uncemented cups in obese patients. Patients with developmental dysplasia and hip fracture were the only diagnostic groups with a significantly decreased risk for cup failure, but only with cemented fixation.
Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.
有关患者特征对全髋关节置换术中杯假体机械失效影响的研究采用了不同的方法，得出的结果并不一致。固定方式很少被研究。因此，我们对患者特征和固定方式对杯假体失败风险的影响进行了详细分析。
我们对 4420 例全髋关节置换术患者进行了病例对照研究，以检验我们的假设，即患者的性别、年龄、体重、体重指数和诊断等特征对骨水泥固定和非骨水泥固定杯假体早期机械失效风险有不同的影响。
与男性（比值比=1）相比，女性骨水泥固定杯（比值比=0.59；95%置信区间，0.43 至 0.83；p=0.002）和非骨水泥固定杯（比值比=0.63；95%置信区间，0.5 至 0.81；p=0.0003）的失败风险显著降低。手术时患者年龄每增加 1 岁，骨水泥固定杯（比值比=0.98；95%置信区间，0.96 至 0.99；p=0.016）和非骨水泥固定杯（比值比=0.98；95%置信区间，0.97 至 0.99；p=0.0002）的失败风险降低 1 倍。在骨水泥固定杯组中，体重为 73 至 82kg 的患者失败风险显著降低（比值比=0.63；95%置信区间，0.4 至 0.98），而体重最轻（<64kg）或最重（>82kg）的患者失败风险则更高（比值比分别为 1.00 和 1.07）。非骨水泥固定组中体重没有显著影响。相比之下，肥胖患者（体重指数>30kg/m2）非骨水泥固定杯的早期失败风险明显高于体重指数<25kg/m2的患者（比值比=1.41；95%置信区间，1.03 至 1.91），而在骨水泥固定臂中，这一影响并不显著。与骨关节炎（比值比=1）相比，发育性髋关节发育不良（比值比=0.52；95%置信区间，0.28 至 0.97）和髋部骨折（比值比=0.38；95%置信区间，0.16 至 0.92）是骨水泥固定杯的保护性因素。
女性和年龄较大对骨水泥固定和非骨水泥固定杯早期失败的风险具有类似的保护作用。尽管骨水泥固定杯在一定的体重范围内有显著的保护作用，但更重要的发现是肥胖患者非骨水泥固定杯的失败风险显著增加。发育性髋关节发育不良和髋部骨折的患者是唯一具有较低杯假体失败风险的诊断组，但仅见于骨水泥固定。
治疗性研究 III 级。有关证据水平的完整描述，请参见《作者须知》。
