TRADITIONAL SEQUENTIAL MEDIAL SOFT TISSUE RELEASE MAY NOT BE THE BEST SEQUENCE FOR BALANCING IN TOTAL KNEE ARTHROPLASTY FOR VARUS KNEES
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IntroductionSoft tissue balancing is an important aspect of total knee replacement surgery. Traditionally sequential medial soft tissue release is performed for balancing in varus deformity. Its effects on kinematics and dynamic Femoro-Tibial-Mechanical-Angle (FTMA) have been described in extension and 90° flexion in coronal plane. However most studies have missed what happens when the knee flexes from 0 to 90 degrees This study is one of the first to describe its effects on knee kinematics throughout flexion. The aim was to look at deviation of FTMA in coronal plane with traditional sequential medial release with and without measured stress applied in varus and valgus at each point of measurement through the range of flexion.Methods12 cadaveric knees were studied using a computer navigation system. Rigid bodies were fixed to femur and tibia. The knee was exposed as per doing TKR surgery with medial parapatellar approach with no disturbance to the collateral ligaments. The anatomy was registered using a i...Keywords:
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Medial collateral ligament
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This cadaver study examined the effects of medial structure release for varus deformity correction during total knee arthroplasty. Twelve specimens were used to investigate the amount of varus correction achieved with sequential release of medial structures. Varus-valgus and internal-external rotation angles were measured using the Isotrack II motion tracking system. Each release sequence was tested at full extension and 45 degrees and 90 degrees of flexion to compare any differences obtained in the joint gaps. After release of the posteromedial capsule oblique ligament complex, superficial medial collateral ligament (MCL), pes anserinus, and semimembranosus tendons, valgus rotation increased to 6.9 degrees in full extension and 13.4 degrees in 90 degrees of flexion. The largest increase (3.2 degrees) in valgus rotation occurred after the superficial MCL was released. Initial release of the superficial MCL led to a more gradual correction with release of subsequent structures. Changes seen in 90 degrees flexion were significantly greater than those in full extension. While the cadaveric model is limited by the lack of deformity in the specimens, the data provide several clinically relevant conclusions. In many cases requiring major medial release for severe varus deformity, potential flexion-extension differences in the resulting tibiofemoral gaps may require new consideration. These data may help explain the heightened interest in and variety of approaches for addressing femoral component rotation and issues of flexion stability since a significantly larger correction is obtained in flexion. Minimal changes in internal-external rotation of the tibia occurred until both the pes anserinus and semimembranosus tendons were released (4 degrees of external rotation).
Cadaveric spasm
Medial collateral ligament
Varus deformity
Valgus deformity
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PurposeSurgeons sometimes encounter moderate or severe varus deformed osteoarthritic cases in which medial substantial release including semimembranosus is compelled to appropriately balance soft tissues in total knee arthroplasty (TKA). However, medial stability after TKA is important for acquisition of proper knee kinematics to lead to medial pivot motion during knee flexion. The purpose of the present study is to prove the hypothesis that step by step medial release, especially semimembranosus release, reduces medial stability in cruciate-retaining (CR) total knee arthroplasty (TKA).MethodsTwenty CR TKAs were performed in patients with moderate varus-type osteoarthritis (10° < varus deformity <20°) using the tibia first technique guided by a navigation system (Orthopilot). During the process of medial release, knee kinematics including tibial internal rotation and anterior translation during knee flexion were assessed using the navigation system at 3 points; (1) after anterior cruciate ligament resecti...
Varus deformity
Internal Rotation
Posterior cruciate ligament
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