Abstract
BackgroundThere have been conflicting studies published regarding the ability of various total knee arthroplasty (TKA) techniques to correct preoperative deformity. The purpose of this study was to compare the postoperative radiographic alignment in patients with severe preoperative coronal deformity (≥10° varus/valgus) who underwent three different TKA techniques; manual instrumentation (MAN), computer navigated instrumentation (NAV) and patient specific instrumentation (PSI).MethodsPatients, who received a TKA with a preoperative coronal deformity of ≥10° with available radiographs were included in this retrospective study. The groups were: MAN; n = 54, NAV; n = 52 and PSI; n = 53. The mechanical axis (varus / valgus) and the posterior tibial slope were measured and analysed using standing long leg- and lateral radiographs.ResultsThe overall mean postoperative varus / valgus deformity was 2.8° (range, 0 to 9.9; SD 2.3) and 2.5° (range, 0 to 14.7; SD 2.3), respectively. The overall outliers (>3°) represented 30.2% (48 /159) of cases and were distributed as followed: MAN group: 31.5%, NAV group: 34.6%, PSI group: 24.4%. No significant statistical differences were found between these groups. The distribution of the severe outliers (>5°) was 14.8% in the MAN group, 23% in the NAV group and 5.6% in the PSI group. The PSI group had significantly (p = 0.0108) fewer severe outliers compared to the NAV group while all other pairs were not statistically significant.ConclusionsIn severe varus / valgus deformity the three surgical techniques demonstrated similar postoperative radiographic alignment. However, in reducing severe outliers (> 5°) and in achieving the planned posterior tibial slope the PSI technique for TKA may be superior to computer navigation and the conventional technique. Further prospective studies are needed to determine which technique is the best regarding reducing outliers in patients with severe preoperative coronal deformity.
Highlights
There have been conflicting studies published regarding the ability of various total knee arthroplasty (TKA) techniques to correct preoperative deformity
The introduction of computer navigation has been associated with fewer outliers [8], but on the other hand, there is conflicting data regarding the radiographic accuracy in the coronal alignment
We decided to use the mean of the two readers (A.H. and C.L.)
Summary
There have been conflicting studies published regarding the ability of various total knee arthroplasty (TKA) techniques to correct preoperative deformity. The purpose of this study was to compare the postoperative radiographic alignment in patients with severe preoperative coronal deformity (≥10° varus/valgus) who underwent three different TKA techniques; manual instrumentation (MAN), computer navigated instrumentation (NAV) and patient specific instrumentation (PSI). The generally accepted radiographic goal in total knee arthroplasty (TKA) is the restoration of a neutral mechanical axis (zero degree +/− three degrees). The three most commonly used techniques for TKA are: 1) the conventional technique with manual instrumentation (MAN) using intramedullary and/or extramedullary jigs to position the cutting blocks; 2) computer navigated instrumentation (NAV) using either an optical or, recently introduced, an electromagnetic wireless system to intraoperatively position the cutting jigs correctly and 3) patient specific instrumentation technique (PSI) using individualized cutting jigs designed from 3D images from the patient’s anatomy (based on a preoperative computer tomography (CT) scan or magnetic resonance imaging (MRI)). The majority of orthopaedic surgeons have not been convinced of computer navigation due to the uncertainty of a true benefit and potential downsides such as longer operating times, issues with bicortical tibial and femoral pins (iatrogenic fractures, infection) and higher costs [15,16,17]
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