Abstract
INTRODUCTION
Studies have reported that only 70–80% of the total knee arthroplasty (TKA) cases using conventional instruments can achieve satisfactory alignment (within ±3° of the mechanical axis). Computer-assisted orthopaedic surgery (CAOS) has been shown to offer increased accuracy and precision to the bony resections compared to conventional techniques [1]. As the early adopters champion the technology, reservation may exist among new CAOS users regarding the ability of achieving the same results. The purpose of this study was to investigate if there are immediate benefits in the accuracy and precision of achieving surgical goals for the novice surgeons, as compared to the experienced surgeons, by using a contemporary CAOS system.
Materials and Methods
Two groups of surgeons were randomly selected from TKAs between October 2012 and January 2016 using a CAOS system (ExactechGPS, Blue-Ortho, Grenoble, FR), including:
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Novice group (7 surgeons): no navigation experience prior to the adoption of the system and have performed ≤20 CAOS TKAs. To investigate the intra-group variation, this group was further divided into surgeons with extensive experience in conventional TKA (novice-senior), and surgeons who were less experienced (novice-junior).
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Experiences group (6 surgeons): used the CAOS system for more than 150 TKAs.
All the surgeries from the novice group (86 cases) and the most recent 20 cases from each surgeon in the experienced group (120 cases) were studied. Deviations in the resection parameters between the following were investigated for both tibia and femur: 1) planned resection, resection goals defined prior to the bone cuts; 2) checked resection, digitization of the realized bone cuts. The deviations were compared within the novice group (novice-senior vs novice-junior), as well as between the novice and experience groups. Knees with optimal resection (deviation<2°/mm, without clinically alter the joint mechanics [2]) and acceptable resection (deviation<3°/mm, as commonly adopted) were identified. Significance was defined as p<0.05.
Results
A summary of the deviations is presented in Table 1. No statistical differences were found between the senior and the junior surgeons in the novice group. Similarly, no differences were found between the experienced group and novice group, except for that the cases in the novice group tended to resect slightly more bone in the tibia (p<0.01), and had slightly larger standard deviations compared to the experienced group. The experienced and novice groups had comparable, high percentages of the knees in both the optimal and acceptable categories (Fig 1).
Discussion
This study demonstrated that regardless of the surgeon's experience with TKA, new adoption of the CAOS system investigated can immediately benefit the accuracy and precision of the bony resections at a comparable level with experience CAOS users. Although significant difference was found between novice and experienced groups in tibial resection depth, the difference (0.57mm) was clinically irrelevant. The CAOS system offers substantial reduction of the outliers compared to TKAs performed with conventional instruments [3].
