Padmanabha Anand, Li Michael T, Tybor David J, Smith Eric L
Department of Orthopedic Surgery, Boston Medical Center, Boston, Massachusetts.
Boston University School of Medicine, Boston, Massachusetts.
J Knee Surg. 2020 Mar;33(3):301-305. doi: 10.1055/s-0039-1677817. Epub 2019 Feb 6.
Incidences and risk factors for tibial component oversizing in total knee arthroplasty (TKA) have been well described, predominantly in Caucasian samples. Component oversizing has been linked to variations in proximal tibial shape and morphology, which has been found to be objectively different in African Americans compared with Caucasians. These anthropometric differences may affect the conformity of modern TKA systems to the anatomy of African Americans undergoing TKA. We sought to investigate the incidence and risk factors for tibial baseplate oversizing in an exclusively African American population undergoing TKA with a symmetric tibial baseplate. We reviewed the records of self-reported African American patients who had undergone a primary TKA at a single academic institution between 2005 and 2016. The primary outcome was incidence of tibial baseplate oversizing in the coronal and sagittal planes as determined by a single set of appropriately rotated postoperative orthogonal radiographs. Logistic regression models identified trends in oversizing within the population based on age, sex, body mass index (BMI), and TKA model. Among all 525 knees being evaluated, the occurrences of medial and lateral overhang were 14.2 and 15.2%, respectively. Increase in age was associated with lower risk of medial tibial overhang (odds ratio = 0.97 for each 1-year increase in age). Simple linear regression models described a linear relationship between BMI and overhang, with every one-unit increase in BMI, medial tibial overhang is 0.031 mm higher and posterior tibial overhang is 0.062 mm higher. Mediolateral oversizing was approximately twice more likely in females than males. Among TKA models used, the Stryker Triathlon had the least risk for mediolateral oversizing and the P.F.C. SIGMA demonstrated the least propensity for anteroposterior oversizing. To conclude, incidence of mediolateral tibial oversizing in this population was common. Previously identified variables affecting proximal tibial morphology, including age, body morphotype, and gender, may be equally applicable to the conformity of tibial baseplates in this population. Surgeons must pay particular attention to avoid mediolateral tibial oversizing in this population, especially in obese and older patients.
全膝关节置换术（TKA）中胫骨假体尺寸过大的发生率及危险因素已得到充分描述，主要是在白种人样本中。假体尺寸过大与近端胫骨形状和形态的变化有关，研究发现非裔美国人与白种人的近端胫骨形状和形态存在客观差异。这些人体测量学差异可能会影响现代TKA系统与接受TKA的非裔美国人解剖结构的匹配度。我们试图调查在接受使用对称胫骨基板的TKA的纯非裔美国人中胫骨基板尺寸过大的发生率及危险因素。我们回顾了2005年至2016年间在单一学术机构接受初次TKA的自我报告为非裔美国人患者的记录。主要结局是通过一组适当旋转的术后正交X线片确定的冠状面和矢状面胫骨基板尺寸过大的发生率。逻辑回归模型根据年龄、性别、体重指数（BMI）和TKA模型确定了人群中尺寸过大的趋势。在所有接受评估的525个膝关节中，内侧和外侧悬垂的发生率分别为14.2%和15.2%。年龄增加与内侧胫骨悬垂风险降低相关（年龄每增加1岁，优势比=0.97）。简单线性回归模型描述了BMI与悬垂之间的线性关系，BMI每增加一个单位，内侧胫骨悬垂增加0.031毫米而后侧胫骨悬垂增加0.062毫米。女性中外侧尺寸过大的可能性约为男性的两倍。在所使用的TKA模型中，史赛克Triathlon外侧尺寸过大的风险最低，而P.F.C. SIGMA前后尺寸过大的倾向最低。总之，该人群中外侧胫骨尺寸过大的发生率很常见。先前确定的影响近端胫骨形态的变量，包括年龄、身体形态类型和性别，可能同样适用于该人群中胫骨基板的匹配度。外科医生必须特别注意避免该人群中外侧胫骨尺寸过大，尤其是肥胖和老年患者。
