股骨远端肿瘤型膝关节假体中长期假体存留及失败类型分析

A comparative statistical long-term survival analysis of modern distal femoral tumor megaprostheses

目的本研究旨在明确股骨远端骨肿瘤切除、肿瘤型膝关节假体重建术后假体的中长期存留使用情况、假体失败的类型,并探讨导致假体失败的主要原因。方法选自1998年至2013年因股骨远端骨肿瘤于我中心行肿瘤切除、股骨远端肿瘤型膝关节假体重建和假体翻修的335个假体进行回顾性研究。对手术性质、假体固定方式、假体设计参数,并发症及处理方式进行统计,同时对患者进行影像学、功能学、肿瘤学随访。平均随访(85.4±49.7)个月,采用Kaplan-Meier法计算存留曲线及假体预期存留率,Log-rank检验行单因素分析,Cox回归进行多因素分析。假体失败根据其原因按国际保肢学会(ISOLS)推荐分类方法分为五型并记录:Ⅰ型:软组织失败;Ⅱ型:无菌性松动;Ⅲ型:结构性失败;Ⅳ型:假体周围感染和Ⅴ型:肿瘤复发累及假体。结果截止到最后一次随访,293例接受股骨远端肿瘤型膝关节假体重建或翻修患者,其中190例无瘤生存,46例带瘤生存,57例死亡,18例截肢。其中8例因假体周围感染截肢,10例因肿瘤复发截肢。对于入组的335个假体,应用K-M曲线法进行假体存留分析中,股骨远端肿瘤型膝关节假体5年存留率78.7%,10年存留率69.2%。根据假体失败的定义标准,共出现假体失败73例。根据ISOLS推荐假体失败类型分类:其中Ⅰ型失败3例,Ⅱ型18例,Ⅲ型16例,Ⅳ型26例,Ⅴ型10例。假体周围感染是导致假体失败的最常见原因,金黄色葡萄球菌为最常见的致病菌。国产与进口型假体总存留间差异无统计学意义(P=0.06);假体缺损段骨水泥固定与生物固定方式间假体存留差异无统计学意义(P=0.95);初治手术假体显著优于翻修手术假体(P=0.04);组配型假体存留优于定制型假体(P=0.02)。针对股骨远端假体应用设计参数的多因素分析显示,股骨远端假体截骨长度<12.5 cm(P=0.03)、假体柄直径>12.5 mm(P=0.01)、柄长>127.5 mm(P=0.003)者存留较优。结论股骨远端肿瘤型膝关节假体能够较好地重建膝关节周围骨肿瘤切除后的骨缺损,但其仍存在一定的失败率,假体周围感染是导致假体失败的最主要原因,须进一步延长随访时间进行观察,同时积极探索降低假体失败率的方式。

Objective To analyze the results of the modern tumor knee megaprosthesis after resection of distal femur bone tumor in regard to：（ 1） prosthesis survivorship;（ 2） major complications and incidence;（ 3） comparative survivorship against different types of reconstruction details. Methods Between 1998 and 2013, 335 cases of tumor resection and prosthetic reconstruction or revision were analyzed especially of distal femur in our center. Prosthetic failures were classified according to the ISOLS recommended classification： Type 1（ soft tissue failure）, Type 2（ aseptic loosening）, Type 3（ structural failure）, Type 4（ infection）, and Type 5（ tumor progression）. The average duration of follow-up was（ 85.4 ± 49.7） months. Kaplan-Meier actuarial curves of implant survival to major failures were done. Comparative statistical analysis of factors affecting survival was made using the Log-rank test and Cox regression method. Results At last follow-up, Kaplan-Meier curve showed an overall prosthetic survival of 78.7% at 5 years and 69.2% at 10 years. 73 failures were recognized in 335 implants（ 21.8%）. Type 1 failure occurred in 3 cases, Type 2 in 18 cases, Type 3 in 16 cases, Type 4 in 26 cases, and Type 5 in 10 cases. Periprosthetic infection was the most dominant reason for prosthetic failure. Staphylococcus aureus was the most common pathogenic bacteria. No statistically significant differences were observed between cemented and uncemented stems（ P = 0.95）, domestic and imported implants（ P = 0.06）. Better implant survival results were found in primary reconstruction group than revision（ P = 0.06）, in modular prostheses than custom-made prostheses（ P = 0.02）. In cox regression analysis of prosthetic design parameters, bone-defect more than 12.5 cm（ P = 0.03）, stem diameter less than 12.5 mm（ P = 0.01）, stem length less than 127.5 mm（ P = 0.003） may result in worse prognosis. Conclusions Results at an average of 7 years follow-up with modern distal femoral prosthesis are satisfactory in terms of survivorship and failure rate whereas infection is the most common failure type. The particularity of each failure type needs further discussion and continuous follow-up.