大多数骨科医师拒绝对极度肥胖的患者进行关节成形术，并引用术后并发症的高发率作为理由。然而，这一建议没有考虑手术时间（肥胖患者的手术时间通常更长）与肥胖相关的关节成形术结果（如再入院、再手术和术后并发症）之间的关系。如果手术时间与这些肥胖相关结果有关联，那么应该进行纠正并加以解决，以正确评估肥胖患者进行THA手术的风险。因此，我们提出以下问题：（1）相对于正常BMI的患者，超重和肥胖患者所见的增加风险是否与手术时间的增加相关？（2）手术时间是否独立于BMI类别是再入院、再手术和术后医学并发症的风险因素？（3）手术时间是否会改变肥胖相关不良结果的方向或强度？本回顾性比较研究检查了在2014年1月至2020年12月间在全国外科质量改进项目（NSQIP）中接受THA手术的247,108名患者。其中，排除了紧急情况（1% [2404]）、双侧手术（1% [1605]）、缺失和/或空值数据（1% [3280]）、极端BMI和手术时间的异常值（1% [2032]）以及患有非典型选择性手术的合并症，如广泛性癌症、创口、脓毒症和通气依赖（1% [2726]），留下95%的选举，单侧THA病例供分析。由于NSQIP包括手术时间，而其他国家数据库没有，因此选择了NSQIP。BMI分为体重过轻、正常体重、超重、I级肥胖、II级肥胖和III级肥胖。正常体重患者中，69%（44,556中的30,932）为女性。36%（44,556中的16,032）至少有一种合并症，平均手术时间为86±32分钟，平均年龄为68±12岁。肥胖患者往往年轻、男性、更有可能有术前并发症，手术时间更长。多变量逻辑回归模型检查了肥胖对30天内再入院、再手术和医学并发症的影响，同时调整了年龄、性别、种族、吸烟状况和术前合并症的数量。在调整手术时间后重复分析后，进行相互作用模型以测试手术时间是否改变BMI类别和不良结果的关系方向或强度。计算了调整后的相对比值（AOR）和95%置信区间（CI），并绘制了相互作用效应。将III级肥胖的患者与正常体重的患者进行比较，调整手术时间后，再入院的可能性从45%（AOR 1.45 [95% CI 1.32至1.59]; p <0.001）降至27%（AOR 1.27 [95% CI 1.01至1.62]; p =0.04），再手术的可能性从93%（AOR 1.93 [95% CI 1.72至2.17]; p <0.001）降至81%（AOR 1.81 [95% CI 1.61至2.04]; p <0.001），术后并发症的可能性从96%（AOR 1.96 [95% CI 1.58至2.43]; p <0.001）降至84%（AOR 1.84 [95% CI 1.48至2.28]; p <0.001）。每增加15分钟手术时间，再入院的可能性增加7%（AOR 1.07 [95% CI 1.06至1.08]; p <0.001），再手术的可能性增加10%（AOR 1.10 [95% CI 1.09至1.12]; p <0.001），术后并发症的可能性增加10%（AOR 1.10 [95% CI 1.08至1.13]; p <0.001）。对于再入院和再手术，手术时间和BMI之间存在积极的相互作用效应，这表明手术时间更长强调了肥胖患者对再入院和再手术的风险。手术时间很可能是外科复杂性的代理变量，并在很大程度上有助于以前仅归因于肥胖患者的不良结果。因此，关注调节手术时间延长所带来的强调风险，而不是肥胖本身，对增加THA的可及性和安全至关重要。外科医生可以通过特定的外科技术、培训和实践来做到这一点。未来研究应考虑与肥胖相关的THA结果与手术时间的关联，以便更好地确定与肥胖独立的联合症。第三级，疗法研究。版权所有©2023年骨科医师协会。

Most orthopaedic surgeons refuse to perform arthroplasty on patients with morbid obesity, citing the higher rate of postoperative complications. However, that recommendation does not account for the relationship of operative time (which is often longer in patients with obesity) to obesity-related arthroplasty outcomes, such as readmission, reoperation, and postoperative complications. If operative time is associated with these obesity-related outcomes, it should be accounted for and addressed to properly assess the risk of patients with obesity undergoing THA.We therefore asked: (1) Is the increased risk seen in overweight and obese patients, compared with patients in a normal BMI class, associated with increased operative time? (2) Is increased operative time independent of BMI class a risk factor for readmission, reoperation, and postoperative medical complications? (3) Does operative time modify the direction or strength of obesity-related adverse outcomes?This retrospective, comparative study examined 247,108 patients who underwent THA between January 2014 and December 2020 in the National Surgical Quality Improvement Project (NSQIP). Of those, emergency cases (1% [2404]), bilateral procedures (1% [1605]), missing and/or null data (1% [3280]), extreme BMI and operative time outliers (1% [2032]), and patients with comorbidities that are not typical of an elective procedure, such as disseminated cancer, open wounds, sepsis, and ventilator dependence (1% [2726]), were excluded, leaving 95% (235,061) of elective, unilateral THA cases for analysis. The NSQIP was selected due to its inclusion of operative time, which is not found in any other national database. BMI was subdivided into underweight, normal weight, overweight, Class I obesity, Class II obesity, and Class III obesity. Of the patients with a normal weight, 69% (30,932 of 44,556) were female and 36% (16,032 of 44,556) had at least one comorbidity, with a mean operative time of 86 ± 32 minutes and a mean age of 68 ± 12 years. Patients with obesity tend to be younger, male, more likely to have preoperative comorbidities, with longer operative times. Multivariable logistic regression models examined the effects of obesity on 30-day readmission, reoperation, and medical complications, while adjusting for age, sex, race, smoking status, and number of preoperative comorbidities. After we repeated this analysis after adjusting for operative time, an interaction model was conducted to test whether operative time changes the direction or strength of the association of BMI class and adverse outcomes. Adjusted odds ratios (AOR) and 95% confidence intervals (CIs) were calculated, and the interaction effects were plotted.A comparison of patients with Class III obesity to patients with normal weight showed that the odds of readmission went from 45% (AOR 1.45 [95% CI 1.32 to 1.59]; p < 0.001) to 27% after adjusting for operative time (AOR 1.27 [95% CI 1.01 to 1.62]; p = 0.04), the odds of reoperation went from 93% (AOR 1.93 [95% CI 1.72 to 2.17]; p < 0.001) to 81% after adjusting for operative time (AOR 1.81 [95% CI 1.61 to 2.04]; p < 0.001), and the odds of a postoperative complication went from 96% (AOR 1.96 [95% CI 1.58 to 2.43]; p < 0.001) to 84% after adjusting for operative time (AOR 1.84 [95% CI 1.48 to 2.28]; p < 0.001). Each 15-minute increase in operative time was associated with a 7% increase in the odds of a readmission (AOR 1.07 [95% CI 1.06 to 1.08]; p < 0.001), a 10% increase in the odds of a reoperation (AOR 1.10 [95% CI 1.09 to 1.12]; p < 0.001), and 10% increase in the odds of a postoperative complication (AOR 1.10 [95% CI 1.08 to 1.13]; p < 0.001). There was a positive interaction effect of operative time and BMI for readmission and reoperation, which suggests that longer operations accentuate the risk that patients with obesity have for readmission and reoperation.Operative time is likely a proxy for surgical complexity and contributes modestly to the adverse outcomes previously attributed to obesity alone. Hence, focusing on modulating the accentuated risk associated with lengthened operative times rather than obesity is imperative to increasing the accessibility and safety of THA. Surgeons may do this with specific surgical techniques, training, and practice. Future studies looking at THA outcomes related to obesity should consider the association with operative time to focus on independent associations with obesity to facilitate more equitable access.Level III, therapeutic study.Copyright © 2023 by the Association of Bone and Joint Surgeons.