Biomechanical Evaluation of Anterolateral Ligament Repair Augmented with Internal Brace

Kinematic effects of unilateral TKA on the contralateral knee in Chinese patients with advanced osteoarthritis: a prospective gait analysis study

Background

Patients with knee osteoarthritis (OA) who receive unilateral total knee arthroplasty (TKA) often report reduced pain and enhanced function in the untreated knee, yet the kinematic mechanisms are not fully understood. Our study aimed to clarify these effects through a gait analysis of the untreated knee following unilateral TKA.

Methods

This study enrolled 118 end-stage OA patients with varus deformity scheduled for TKA, categorized into the contralateral osteoarthritis group (Contra-OA), consisting of patients with end-stage OA in both knees requiring surgical treatment, and the contralateral TKA group (Contra-TKA), which included patients who had undergone TKA on one knee and had end-stage OA in the untreated knee awaiting surgery. Kinematic data of the knee joint during treadmill walking were collected using the Opti_Knee gait analysis system, and a comparative analysis was conducted.

Results

The Contra-TKA group exhibited improvements in step length, anterior-posterior translation, range of motion, vertical translation, and internal-external rotation compared to the Contra-OA group (p-values ranging from 0.0013 to 0.0463). Notable differences in flexion-extension angles and abduction/adduction rotation were also observed (p = 0.0013 and 0.0166, respectively). At the initial contact (IC), obvious differences in internal-external rotation, anterior/posterior translation, and vertical translation were noted. At the opposite toe-off (OT), significant differences in internal-external rotation. At the tibia vertical (TV) moment, significant differences were observed in all three translation indicators of joint translation. At other pivotal gait cycle points, vertical and anterior/posterior translations in Contra-TKA group continued to exhibit more meaningful decrease. Collectively, these findings underscore the protective kinematic effects of TKA on the untreated contralateral knee, indicating an improved biomechanical adaptation following TKA surgery.

Conclusion

In summary, the study's findings indicate that unilateral TKA imparts kinetic effects on the untreated contralateral knee, as evidenced by significant improvements in key gait parameters. These enhancements, observed at both initial contacts and throughout the gait cycle, suggest a positive biomechanical support post-TKA, might contribute to better gait efficiency and reduced load on the contralateral untreated knee.

Ulnar Collateral Ligament Repair With Suture Tape Augmentation: Can You Overtighten?

BACKGROUND

There has been a renewed interest and, recently, wider implementation of ulnar collateral ligament (UCL) repair in throwing athletes because of improvement in ligament repair technology and corresponding outcome data.

PURPOSE

To compare the biomechanical parameters and failure mode between 2 brace-tightening techniques for UCL repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven matched pairs of cadaveric arms were procured. One limb from each pair underwent UCL repair with suture tape augmentation with either (1) attempted restoration of physiologic ligament tension or (2) maximal tension. Each specimen was subjected to 10 cycles of subfailure valgus torque at 90º of flexion in the intact state after UCL avulsion and then after UCL repair. Specimens were then torqued to failure. Articular contact mechanics, linear gap distance, angular displacement, failure torque, failure stiffness, and suture tape pull-through length were recorded. Two-way analysis of variance and paired t tests were used to test for statistical differences.

RESULTS

There was a significant effect (P = .01) of tightening on joint contact area. There was a significant decrease in gap distance (P = .03) and angular displacement (P = .004) from the torn condition to the repaired condition for the maximum tension group, without a significant difference in gap distance from the intact condition. Failure torque and stiffness were not significantly different between groups, although there was a significant difference (P = .001) in the overall suture tape pull-through length.

CONCLUSION

Although there are potential physiologic changes at time zero-including significant decreases in contact area, normalized gap distance, and normalized angular displacement with maximal tension repair-examination of failure biomechanics suggests that these effects may be mitigated over time within the construct by suture tape pull-through at the tape-anchor interface. Neither method of UCL repair with suture tape augmentation resulted in overconstraint of the elbow joint compared with the native ligament biomechanics.

CLINICAL RELEVANCE

As more long-term outcome data from UCL repair with suture tape augmentation emerge, there will be wider implementation with various techniques to tension the suture tape. Examining the potential biomechanical sequelae of the UCL repair construct applied under maximal tension will help further refine recommendations for surgeons who utilize this technique for UCL repair.