POSTEROMEDIAL MENISCAL AND ANTERIOR CRUCIATE LIGAMENT STRAINS DURING DYNAMIC ACTIVITIES FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background: Meniscal strain patterns are not well understood during dynamic activities. Furthermore, the impact of ACL reconstruction on meniscal strain has not been thoroughly investigated. The purpose of this study was to characterize ACL and meniscal strain during dynamic activities and investigate the strain difference between ACL-intact and ACL-reconstructed ligament conditions. Methods: ACL and medial meniscal strain were measured in-vitro during gait, a double leg squat, and a single leg squat. For each activity kinematics and muscle forces were applied to seven cadaveric specimens using a dynamic knee simulator. Testing was performed in the ACL-intact and ACL-reconstructed ligament conditions. Results: Both the ACL and meniscus had distinct strain patterns that were found to have a significant interaction with knee angle during gait and double leg squat ([Formula: see text]). During gait, both tissues experienced lower strain during swing than stance (ACL: 3.0% swing, 9.1% stance; meniscus: 0.2% swing, 1.3% stance). Meniscal strain was not found to be different between ACL-intact and ACL-reconstructed conditions ([Formula: see text]). Conclusions: During dynamic activities, the strain in the meniscus was not altered between ACL ligament conditions. This indicates that meniscal mechanics after ACL reconstruction are similar to a healthy knee. These results help further the understanding of osteoarthritis risk after ACL reconstruction.

Computational Muscle Driven Knee Simulator for Assessment of Total Knee Replacement Post-Cam Mechanics

Biomechanics of post-cam mechanism is essential in determining the longevity of knee implant. Computational knee simulator is an efficient method in characterizing TKA performance under various boundary conditions. The existing knee simulators, however, were actuated only by quadriceps translation and hip load to perform squatting motion. The present computational knee simulator was developed based on lower limb of Japanese female subject having body weight, W = 51 kg and height, H = 148 cm. Two different designs of PS-type knee prostheses were tested namely Superflex and NRG. The knee motion was driven by three major muscles; quadriceps, hamstrings and gastrocnemius. The biomechanical behavior of tibiofemoral articulation associated with post-cam engagement mechanics was observed. Post-cam engagement occurred at 80° and 65° of flexion angles for Superflex and NRG, respectively. Maximum von Mises stresses at tibial post were 80 MPa and 50 MPa for Superflex and NRG, respectively. The developed computational muscle driven knee simulator has successfully assessed the performance of TKA prostheses.

Efficacy of a Virtual Arthroscopic Simulator for Orthopaedic Surgery Residents by Year in Training

Background: Virtual reality arthroscopic simulators are an attractive option for resident training and are increasingly used across training programs. However, no study has analyzed the utility of simulators for trainees based on their level of training/postgraduate year (PGY). Purpose/Hypothesis: The primary aim of this study was to determine the utility of the ArthroS arthroscopic simulator for orthopaedic trainees based on their level of training. We hypothesized that residents at all levels would show similar improvements in performance after completion of the training modules. Study Design: Descriptive laboratory study. Methods: Eighteen orthopaedic surgery residents performed diagnostic knee and shoulder tasks on the ArthroS simulator. Participants completed a series of training modules and then repeated the diagnostic tasks. Correlation coefficients ( r2) were calculated for improvements in the mean composite score (based on the Imperial Global Arthroscopy Rating Scale [IGARS]) as a function of PGY. Results: The mean improvement in the composite score for participants as a whole was 11.2 ± 10.0 points ( P = .0003) for the knee simulator and 14.9 ± 10.9 points ( P = .0352) for the shoulder simulator. When broken down by PGY, all groups showed improvement, with greater improvements seen for junior-level residents in the knee simulator and greater improvements seen for senior-level residents in the shoulder simulator. Analysis of variance for the score improvement variable among the different PGY groups yielded an f value of 1.640 ( P = .2258) for the knee simulator data and an f value of 0.2292 ( P = .917) for the shoulder simulator data. The correlation coefficient ( r2) was –0.866 for the knee score improvement and 0.887 for the shoulder score improvement. Conclusion: Residents training on a virtual arthroscopic simulator made significant improvements in both knee and shoulder arthroscopic surgery skills. Clinical Relevance: The current study adds to mounting evidence supporting virtual arthroscopic simulator–based training for orthopaedic residents. Most significantly, this study also provides a baseline for evidence-based targeted use of arthroscopic simulators based on resident training level.

Efficacy of an Arthroscopic Virtual Based Simulator for Orthopedic Surgery Residents by Year in Training

Objectives: Arthroscopic virtual-reality stimulators are an attractive option for resident training and are increasing across training programs. However, no study has analyzed the utility of the simulator for trainees based on their post-graduate level of training (PGY-level). The primary aim of this study was to determine the utility of the ArthroSTM arthroscopic simulator for orthopedic trainees based on their level of training (to determine at what point in training the simulator offers the most benefit for trainees). We hypothesized that all levels would show similar improvements in performance following completion of the training modules. Methods: Eighteen orthopedic surgery residents performed pre-training diagnostic knee and shoulder tasks on the ArthoSTM simulator. Subjects completed a series of training modules, then repeated the diagnostic tasks. Mean composite scores were calculated. Group differences for discrete variables were evaluated using ANOVA (analysis of variance). Correlation coefficients (R2) were calculated for improvements in mean composite score as a function of subject year-in-training. Results: Average improvement in composite score for participants as a whole was 11.2 points [SD 10; p-value 0.0003] for the knee simulator and 14.9 points [SD 10.9; p-value 0.0352] for the shoulder simulator. When broken down by PGY-level, all groups showed improvement, with greater improvements seen for junior-level residents in the knee simulator and greater improvements seen for senior-level residents in the shoulder simulator. ANOVA for the score improvement variable in the knee simulator data amongst the different PGY-groups yielded an f-value of 1.640 (p-value 0.2258) and that for the shoulder simulator data amongst the different PGY-groups yielded an f-value of 0.2292 (p-value 0.917). The correlation coefficient (r2) was -0.866 for the knee score improvement and 0.887 for the shoulder score improvement (Image 1). Conclusion: We found that residents training on a virtual arthroscopic simulator made significant improvements in both knee and shoulder arthroscopic skills. Most importantly, we report for the first time that the knee simulator appears to be more beneficial for junior residents, while the shoulder simulator appears to be more beneficial for senior residents. Our study adds to the mounting evidence supporting virtual arthroscopic simulator-based training for orthopedic surgery residents.