胫骨后倾角的解读依赖于测量方法：初次与复发性ACL断裂中定义异常无通用阈值
简介
本研究回顾性分析609例受试者（ACL完整组470例、初次ACL断裂组88例、ACL再断裂组51例），采用5种方法在标准化侧位X线片上测量胫骨后倾角（PTS）。结果显示：ACL完整组平均PTS为5.9°-8.2°，异常PTS通常>12°-15°（因测量方法而异）。基于参考人群的阈值，初次ACL断裂组中18.2%-22.7%存在异常PTS，ACL再断裂组中这一…
英文摘要
PURPOSE: To determine method-specific normal posterior tibial slope (PTS) values, define abnormal PTS using two statistical approaches, and assess how abnormal PTS classification varies in primary anterior cruciate ligament (ACL) rupture and ACL re-rupture. METHODS: In this retrospective single-centre study, all patients undergoing knee imaging during the study period were screened and categorized into three groups based on clinical and imaging findings: ACL-intact, primary ACL rupture and ACL re-rupture. PTS was measured on standardized lateral radiographs using five techniques. Normal values were defined as the 95% reference interval (2.5th-97.5th percentiles). Abnormal PTS was defined using both a quantile-based approach and a standard deviation-based approach. Statistical significance was set at p < 0.05. RESULTS: A total of 609 subjects were included (mean age 30 ± 5 years; 304 males and 305 females), comprising an ACL-intact reference group (n = 470), a primary ACL rupture group (n = 88) and an ACL re-rupture group (n = 51). Mean PTS in the reference group ranged from 5.9° to 8.2°, with increased PTS generally observed above 12-15°, depending on the technique. Using reference-based thresholds, abnormal PTS was identified in 18.2%-22.7% of ACL patients and 35.3%-41.2% of ACL re-rupture patients, with significantly higher proportions in the latter (p = 0.009-0.036). Using standard deviation-based thresholds, abnormal PTS was identified in 17.0%-20.5% and 27.5%-37.3% of patients, respectively. When thresholds were derived from the ACL population, abnormal PTS classification in ACL re-rupture decreased (2.0%-9.8%) and was no longer significantly different (all p ≥ 0.532). CONCLUSION: PTS interpretation is highly method-dependent. Normal ranges and abnormal classification vary according to measurement technique, statistical definition and reference population. A universal PTS cut-off is therefore inappropriate. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort study.