Restoration of the Joint Line Configuration Reproduces Native Mid-Flexion Biomechanics after Total Knee Arthroplasty: A Matched-Pair Cadaveric Study

Abstract

Background: Recent evidence supports that restoration of the pre-arthritic condition via total knee arthroplasty (TKA) is associated with improved post-TKA performance and patient satisfaction. However, whether the restored pre-arthritic joint line simulates the native mid-flexion biomechanics remains unclear. Objective: We performed a matched-pair cadaveric study to explore whether restoration of the joint line via kinematically aligned (KA) TKA reproduced native knee biomechanics more accurately than the altered joint line associated with mechanically aligned (MA) TKA. Methods: Sixteen fresh-frozen cadaveric knees (eight pairs) were affixed onto a customized knee-squatting simulator for measurement of femoral rollback and medial collateral ligament (MCL) strain during mid-flexion. One knee from each cadaver was randomly designated to the KA TKA group (with the joint line restored to the pre-arthritic condition) and the other to the MA TKA group (with the joint line perpendicular to the mechanical axis). Optical markers were attached to all knees and rollback was analyzed using motion capture cameras. A video extensometer measured real-time variations in MCL strain. The kinematics and MCL strain prior to and following TKA were measured for all specimens. Results: KA TKA was better for restoring the knee kinematics to the native condition than MA TKA. The mid-flexion femoral rollback and axial rotation after KA TKA were consistently comparable to those of the native knee. Meanwhile, those of MA TKA were similar only at ≤40° of flexion. Furthermore, KA TKA better restored the mid-flexion MCL strain to that of the native knee than MA TKA. Over the entire mid-flexion range, the MCL strain of KA TKA and native knees were similar, while the strains of MA TKA knees were more than twice those of native knees at >20° of flexion. Conclusions: The restored joint line after KA TKA effectively reproduced the native mid-flexion rollback and MCL strain, whereas the altered joint line after MA TKA did not. Our findings may explain why patients who undergo KA TKA experience superior outcomes and more natural knee sensations during daily activities than those treated via MA TKA.

Effects of Unrestricted Kinematically Aligned Total Knee Arthroplasty with a Modified Soft-Tissue Respecting Technique on the Deformity of Limb Alignment in Japanese Patients

“…Theoretically, KA-TKA can reproduce medial stability in the entire range of motion to restore the positional relationship between the pre-osteoarthritic joint line and MCL. Unrestricted KA-TKA has been reported to better reproduce the native mid-flexion rollback and MCL strain compared to MA-TKA [25,26], indicating that restoring the pre-osteoarthritis relationship between the medial side of the femur and tibia may improve knee kinematics. Moreover, unrestricted KA-TKA with the modified STRT requires double-checking by surgeons.…”

A Pilot Experiment to Measure the Initial Mechanical Stability of the Femoral Head Implant in a Cadaveric Model of Osteonecrosis of Femoral Head Involving up to 50% of the Remaining Femoral Head

“…This enables orthopedic surgeons to assess biomechanical characteristics and properties. Indeed, biomechanical cadaveric studies play a role in performing a pre-clinical assessment of new surgical techniques and implant designs [ 54 , 55 , 56 ]. This justifies the current biomechanical cadaveric study.…”

Advances in Biomechanics-Based Motion Analysis

“…Using multibody models, Herteleer et al [ 11 ] continuously monitored shoulder joint angles in patients after surgeries of humerus fractures, and examined the effects of different rehabilitation protocols, i.e., early postoperative mobilization vs. immobilization, on the shoulder joint motions. Similarly, Kwak et al [ 2 ] compared knee joint kinematics following two different protocols of total knee arthroplasty to evaluate the effectiveness of the treatments. However, when some newly proposed interventions cannot be conducted directly on human subjects due to ethical reasons, FEMs can help simulate how interventions may cause changes in specific biomechanical indicators in vitro and simulate the possible clinical outcomes.…”

“…Moreover, the in-depth biomechanical/neuromuscular mechanisms of motion patterns are poorly understood. Therefore, in this Special Issue, we have assembled 23 research articles and review papers on the state-of-the-art advances in motion analysis from fundamental in vitro cell [ 1 ] and cadaveric studies [ 2 ] to in vivo experiments on human subjects. These studies have either applied validated biomechanical models and neuromuscular analyses to answer unresolved clinical/sports-related questions or focused on the development of novel motion analysis methods.…”