Yann Diesinger

High Activity Arthroplasty Score has a Lower Ceiling Effect Than Standard Scores After Knee Arthroplasty

The tested hypothesis was following: the High Activity Arthroplasty Score has a significant lower ceiling effect than American Knee Society Score and Oxford Knee Score after total knee arthroplasty. One hundred patients operated on for total knee arthroplasty with more than one-year follow-up have been included. The ceiling effect was 53% for the American Knee Society Score, 33% for the Oxford Knee Score, and 0% for the High Activity Arthroplasty Score. High Activity Arthroplasty Score had a significantly lower ceiling effect than American Knee Society Score and Oxford Knee Score. High Activity Arthroplasty Score has the potential to detect more subtle differences in level of function than standard scoring systems among a non-selected total knee arthroplasty population.

Measurement of the knee flexion angle with smartphone applications: Which technology is better?

AbstractPurpose The range of motion of the knee is a critical element of clinical assessment. The tested hypothesis was that the measurement of the knee flexion angle measured with two specific smartphone applications using either inclinometer or camera technology was different from the reference measurement with a navigation system designed for total knee arthroplasty (TKA).MethodsTen consecutive patients were selected for navigation-assisted TKA. Five navigated, five inclinometer and five camera measurements of knee flexion angle were obtained for each patient throughout the complete range of motion. The difference, the correlation and the coherence between all measurements and all paired sub-groups were analysed.ResultsThere was a strong correlation and a good coherence between the three techniques of measurements, but the knee flexion angle reported by the inclinometer differed substantially from the camera- and navigation-based measurements. The camera-based measurement was clinically identical to the navigated data, with a mean difference of <1° and only 1/50 difference >3°.ConclusionCamera-based smartphone measurement of the knee range of motion is fit for purpose in a routine clinical setting. The accuracy may be higher than other conventional measurement techniques, allowing a more precise rating of the clinical outcomes after TKA.Level of evidenceII.

Navigated revision TKR: a comparative study with conventional instruments.

We selected 86 cases for the study: 50 navigated revision total knee replacements (TKRs) and 36 conventional revision TKRs. We hypothesized that the rate of satisfactory implantation would be higher for navigated revision TKR than for conventional revision TKR. The primary criterion was the rate of optimally implanted prostheses on postoperative anteroposterior and lateral long leg radiographs. Thirty-one navigated cases (62%) and 14 conventional cases (39%) had an optimal global implantation (P<.05). The use of a standard navigation software for revision TKR allows a significant improvement of the accuracy of implantation. However, development of dedicated software will allow addressing more precisely the specific features of a revision TKR, such as stem extension navigation, defects filling, and joint line reconstruction.

Paper # 226: Navigated Total Knee Prosthesis Exchange: A Comparative Study With Conventional Technique

INTRODUCTION Revision total knee replacement (TKR) is a challenging procedure, especially because most of the standard bony and ligamentous landmarks used during primary TKR are lost due to the index implantation. However, as for primary TKR, restoration of the joint line, adequate limb axis correction and ligamentous stability are considered critical for the short- and long- term outcome of revision TKR. Navigation system might address this issue. MATERIAL AND METHODS We are using an image-free system (ORTHOPILOT TM, AESCULAP, FRG) for routine implantation of primary TKR. The standard software was used for revision TKR. Registration of anatomic and cinematic data was performed with the index implant left in place. The components were then removed. New bone cuts as necessary were performed under the control of the navigation system. The system did not allow navigation for intra-medullary stem extensions and any bone filling which may have been required. This technique was used for 37 patients. The accuracy of implantation was assessed by measuring following angles on the post-operative long-leg radiographs: mechanical femoro-tibial angle, coronal orientation of the femoral component in comparison to the mechanical femoral axis, coronal orientation of the tibial component in comparison to the mechanical tibial axis, sagittal orientation of the tibial component in comparison to the proximal posterior tibial cortex. Individual analysis was performed as follows: one point was given for each fulfilled item, giving a maximal accuracy note of 4 points. Prosthesis implantation was considered as satisfactory when the accuracy note was 4 (all fulfilled items). The rate of globally satisfactory implanted prostheses and the rate of prostheses implanted within the desired range for each criterion were recorded. The results of the 37 navigated revision TKR were compared to 26 cases of revision TKR performed with conventional intramedullary guiding systems. RESULTS We observed a significant improvement of all radiological items by navigated cases. Limb alignment was restored in 82% of the navigated cases and 74% of the conventional cases. The coronal orientation of the femoral component was acceptable in 85% of the navigated cases and 76% of the conventional cases. The coronal orientation of the tibial component was acceptable in 95% of the navigated cases and 89% of the conventional cases. The sagittal orientation of the tibial component was acceptable in 77% of the navigated cases and 66% of the conventional cases. Overall, 50% of the implants were oriented satisfactorily for the four criteria for navigated cases, and only 40% for conventional cases. DISCUSSION The navigation system enables reaching the implantation goals for implant position in the large majority of cases, with a rate similar to that obtained for primary TKA. The rate of optimally implanted prosthesis was significantly higher with navigation than with conventional technique. The navigation system is a useful aid for these often difficult operations, where the visual information is often misleading.