Ganokroj Phob, Polklaew Trakul, Lertwanich Pisit
Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Department of Orthopaedic Surgery, Paholpolpayuhasena Hospital, Kanchanaburi, Thailand.
Asia Pac J Sports Med Arthrosc Rehabil Technol. 2018 Dec 21;16:1-7. doi: 10.1016/j.asmart.2018.12.001. eCollection 2019 Apr.
BACKGROUND/OBJECTIVE: Graft-tunnel length mismatch is a common intraoperative technical problem for anterior cruciate ligament reconstruction (ACLR) using a bone-patellar tendon-bone graft (BPTB). The patella-to-condyle and the patella-to-notch distances are two measurements in an anteroposterior knee radiograph. The objective of this study was to evaluate the sensitivities, specificities and reliabilities of those 2 measurements for detecting patients who had a patellar tendon length exceeding 45 mm.
Preoperative plain radiographs of patients who underwent ACLR with a BPTB graft were evaluated independently by two orthopaedic surgeons 3 times each at 2-weekly intervals. The sensitivities and specificities of the two measurements for detecting patients who have a patellar tendon length exceeding 45 mm were calculated. The optimal cutoff point was estimated using Youden index, and the receiver operating characteristic (ROC) curve and area under the curve (AUC) were evaluated with a 95% CI. As for the inter- and intra-rater reliabilities, intraclass correlation coefficients (ICC) were determined.
One hundred and twenty-seven patients with an average age of 29.5 years old were evaluated. The mean patellar tendon length was 41.3 ± 5.0 mm. Patients with a length more than 45 mm (20 patients, 16%) had significantly higher patella-to-condyle and patella-to-notch distances, and more frequent use of bone staples for distal graft fixation than patients with a length ≤ 45 mm. To detect patients with a patellar tendon length over 45 mm, the optimal cutoff point for the patella-to-condyle distance was set at 14.5 mm, which had a sensitivity of 80%, specificity of 71%, and AUC of 0.76. In the case of the patella-to-notch distance, the cutoff point of 5.5 mm had a sensitivity of 80%, specificity of 66%, and AUC of 0.73. The intra- and inter-rater reliabilities of the two measurements were excellent, with ICCs of over 0.90.
Preoperative measurements of the patella-to-condyle and the patella-to-notch distances in AP knee radiographs can be valuable tools, with good sensitivities and specificities, for the determination of the patellar tendon length when using a BPTB graft for an ACLR. They had an acceptable level of discrimination capability and excellent reliability.
背景/目的：移植物-隧道长度不匹配是使用骨-髌腱-骨移植物（BPTB）进行前交叉韧带重建（ACLR）时常见的术中技术问题。髌骨至髁间和髌骨至髁间切迹的距离是膝关节前后位X线片上的两项测量指标。本研究的目的是评估这两项测量指标在检测髌腱长度超过45 mm患者时的敏感性、特异性和可靠性。
对接受BPTB移植物ACLR的患者术前X线平片，由两名骨科医生独立评估，每隔2周评估3次。计算两项测量指标在检测髌腱长度超过45 mm患者时的敏感性和特异性。使用约登指数估计最佳截断点，并评估受试者工作特征（ROC）曲线和曲线下面积（AUC），95%置信区间。对于评估者间和评估者内的可靠性，确定组内相关系数（ICC）。
共评估了127例平均年龄29.5岁的患者。髌腱平均长度为41.3±5.0 mm。髌腱长度超过45 mm的患者（20例，16%）的髌骨至髁间和髌骨至髁间切迹距离显著更高，且与髌腱长度≤45 mm的患者相比，远端移植物固定时使用骨钉的频率更高。为检测髌腱长度超过45 mm的患者，髌骨至髁间距离的最佳截断点设定为14.5 mm，其敏感性为80%，特异性为71%，AUC为0.76。对于髌骨至髁间切迹距离，截断点为5.5 mm时，敏感性为80%，特异性为66%，AUC为0.73。两项测量指标的评估者间和评估者内可靠性均极佳，ICC超过0.90。
膝关节前后位X线片上术前测量髌骨至髁间和髌骨至髁间切迹的距离，对于使用BPTB移植物进行ACLR时确定髌腱长度而言，可能是具有良好敏感性和特异性的有价值工具。它们具有可接受的辨别能力水平和出色的可靠性。
