Wongsak Siwadol, Kawinwonggowit Viroj, Mulpruck Pornchai, Channoom Thanaphot, Woratanarat Patarawan
Department of Orthopaedics, Faculty of Medicine Ramathibodi Hospital, Mahidol Universit, Bangkok, Thailand.
J Med Assoc Thai. 2009 Dec;92 Suppl 6:S85-90.
Accurate preoperative templating to predict implant size and position can facilitate precise, efficient, and reproducible knee replacement operations. Preoperative templating for total knee arthroplasty can be performed with digital images of the knee implants on digital radiographs of the knee.
To determine the accuracy of knee implants sizing predicted by digital images.
A retrospective study was done to assess the accuracy of the knee implant sizing predicted by digital images in 100 Thai adults, who had osteoarthritis of the knee. Digital anteroposterior and lateral radiographs of the knee were used in measuring the level of distal femoral resection and the level of proximal tibial resection. Anteroposterior and mediolateral diameter of femur and tibia were determined and the implant size was choosen. The results from digital images were compared with the size of actual femoral and tibial implants used at the time of surgery. All variables were analyzed. The correlation coefficients were calculated to determine interobserver and intraobserver reliability.
The accuracy of digital preoperative plans for femoral component was 53.1%. The accuracy of digital preoperative plans for tibial component was 59.3%. The digital preoperative planning predicted 79 of 81 (97.6%) femoral implants to within one size and predicted 77 of 81 (95.1%) measurements of the tibial implants to within one size.
Digital images can help to focus the thoughts and plans of the operation. When planning is performed, it can identify extremes of sizes that may require special order, and planning can predict size mismatches between femoral and tibial implants. When recognized ahead of time, these limitations can be accommodated during the surgical procedure or a different implant system chosen. Predicting implant sizes to within one size allows efficient anticipation by the orthopaedic surgeon.
准确的术前模板设计以预测植入物大小和位置，有助于实现精确、高效且可重复的膝关节置换手术。全膝关节置换术的术前模板设计可通过膝关节数字X线片上的膝关节植入物数字图像来进行。
确定通过数字图像预测的膝关节植入物大小的准确性。
进行一项回顾性研究，以评估100名患有膝关节骨关节炎的泰国成年人通过数字图像预测的膝关节植入物大小的准确性。使用膝关节的前后位和侧位数字X线片测量股骨远端截骨水平和胫骨近端截骨水平。确定股骨和胫骨的前后径及内外侧径，并选择植入物大小。将数字图像的结果与手术时使用的实际股骨和胫骨植入物的大小进行比较。对所有变量进行分析。计算相关系数以确定观察者间和观察者内的可靠性。
股骨部件数字术前计划的准确性为53.1%。胫骨部件数字术前计划的准确性为59.3%。数字术前计划将81个股骨植入物中的79个（97.6%）预测在一个尺寸范围内，将81个胫骨植入物测量中的77个（95.1%）预测在一个尺寸范围内。
数字图像有助于聚焦手术思路和计划。在进行计划时，它可以识别可能需要特殊订购的极端尺寸，并能预测股骨和胫骨植入物之间的尺寸不匹配。如果提前识别出这些局限性，可在手术过程中加以应对，或选择不同的植入系统。将植入物大小预测在一个尺寸范围内可让骨科医生进行有效的预期。
