We systematically reviewed the published literature on the complications of closing wedge high tibial osteotomy for the treatment of unicompartmental osteoarthritis of the knee. Publications were identified using the Cochrane Library, MEDLINE, EMBASE and CINAHL databases up to February 2012. We assessed randomised (RCTs), controlled group clinical (CCTs) trials, case series in publications associated with closing wedge osteotomy of the tibia in patients with osteoarthritis of the knee and finally a Cochrane review. Many of these trials included comparative studies (opening wedge versus closing wedge) and there was heterogeneity in the studies that prevented pooling of the results.

We designed this study to determine the clinical evidence to support use of the five degree tibial extra-medullary cutting block over the zero degree cutting block.

We identified three groups of patients from the databases and clinical notes at St Michaels Hospital, Toronto. Group one were primary total knees performed using the five degree cutting block, group two were primary total knees performed using the zero degree cutting block and the third group were computer navigated primary total knees. Patients in all three groups were age and sex matched. The senior author advocating use of the five degree block aimed to obtain a five degree posterior slope. The senior author who advocated the use of computer navigation, or the traditional zero degree cutting block, aimed to obtain a three degree posterior slope. All operations were performed by residents or clinical fellows, under the supervision of the senior authors. Patient radiographs were assessed to obtain the optimal direct lateral view obtained and they were saved on a database. Two independent blinded researchers assessed the posterior slope using Siemens Magicweb Software Version VA42C_0206. Two methods were used and the results averaged. The average posterior slope for the navigated total knee replacements was 0.1 degrees (−2 to 4). The average posterior slope for the five degree cutting block was 5.2 degrees (−2 to 16). The average posterior slope for the zero degree block was 3.79 degrees (−2 to 13). Computer navigated knee arthroplasty patients had significantly less variation in outlier measurements compared to the traditionally jigged arthroplasty patients. They were however, less accurate. The five degree cutting block tended to provide a more consistent posterior slope angle, but both the five degree and zero degree cutting blocks had variability in outliers. Computer Navigated Total Knee replacement provides a more consistent and reproducible tibial cut with less variability in alignment than extra-medullary jigs. The traditional five degree cutting block tended to provide a more reliable five degree posterior slope than the zero degree block, but was still subject to outliers.

The purpose of this study was to evaluate 3 methods used to produce posterior tibial slope.

Purpose: The purpose of this study was to evaluate the accuracy and precision of 3 common methods used to produce posterior tibial slope during total knee arthroplasty.

Method: The study population consisted of 110 total knee arthroplasties in 102 patients that underwent total knee arthroplasty. All procedures were performed using a standard medial parapatellar approach and all knees were replaced using the Scorpio Knee System (Stryker, Mahwah, NJ) of implants and instruments. Three treatment groups were identified retrospectively based on the method used to produce the posterior tibial slope. Group 1 used an extramedullary guide with a 0 degree cutting block tilted by placing 2 fingers between the tibia and the extramedullary guide proximally and three fingers between the tibia and guide distally to produce a 3 degree posterior slope (N=40). Group 2 used computer navigation (Stryker Navigation System, Stryker, Mahwah, NJ) to produce a 3 degree posterior slope (N=30). Group 3 used an extramedullary guide placed parallel to the anatomic axis of the tibia with a 5 degree cutting block to produce a 5 degree posterior slope (N=40). Posterior tibial slope was measured from lateral radiographs by 2 independent reviewers that were blinded to the treatment group. The reported posterior tibial slope for each sample was an average of these two measurements. Accuracy of the treatment group was evaluated using a one sample t test. Groups 1 and 2 were tested for an ideal slope of 3 degrees, and Group 3 was tested for an ideal slope of 5 degrees. An a priori sample size calculation with α=0.05 and β=0.20 showed that at least 24 samples in each treatment group were required to determine a difference of 1.5 degrees between the treatment group mean posterior tibial slope and the ideal posterior tibial slope.

Results: The mean posterior slope measurements for treatment Group 1 (4.15±3.24 degrees) and treatment Group 2 (1.60±1.62 degrees) were both significantly different than the ideal slope of 3 degrees (p=0.03 for Group 1 and p< 0.01 for Group 2). This indicates that treatment Groups 1 and 2 failed to accurately produce the ideal posterior tibial slope of 3 degrees. The mean posterior tibia slope of treatment Group 3 (5.00±2.87 degrees) was not significantly different than the ideal posterior tibial slope of 5 degrees (p=1.00). This indicates that Group 3 accurately produced the ideal tibial slope of 5 degrees.

Conclusion: The most accurate method to produce posterior tibial slope was the 5 degree cutting block with an extramedullary guide. Computer navigation had the lowest standard deviation and therefore was the most precise method. However, computer navigation was not as accurate in producing the desired posterior tibial slope as the extramedullary guide with the 5 degree cutting block. The manual method of producing tibial slope with an extramedullary guide and a 0 degree cutting block was the least precise method and not as accurate as the extramedullary guide with a 5 degree cutting block.