سنسور متعادل کننده حرکتی در آرتروپلاستی زانو
Abstract
Introduction
Material and methods
Results
Discussion
Conclusions
References
Abstract
Background: Dynamic tibial tray sensors are playing an increasing role in total knee arthroplasty (TKA) coronal balancing. Sensor balance is proposed to lead to improved patient outcomes compared with sensor-unbalanced TKA, and traditional manual-balanced TKA. However, the “learning curve” of this technology is not known, and also whether sensor use can improve manual TKA balance skills once the sensor is taken away, effectively “training” the surgeon.
Methods: We conducted a single-surgeon prospective study on 104 consecutive TKAs. In Nonblinded Phase I (n ¼ 49), sensor-directed releases were performed during trialing and final intercompartmental load was recorded. In Blinded Phase II (n ¼ 55), manual-balanced TKA was performed and final sensor readings were recorded by a blinded observer after cementation. We used cumulative summation analysis and sequential probability ratio testing to analyze the surgeon learning curve in both phases. Results: In Nonblinded Phase I, sensor balance proficiency was attained most easily at 10, followed by 90, and most difficult to attain at 45 of flexion. In Blinded Phase II, manual balance was lost most quickly at 45, followed by 90, and preserved for longest at 10 of flexion. The number of cases in the steady state periods (early phase periods where there is a mix of sensor balance and sensor imbalance) for both phases is similar.
Conclusions: A surgeon who consistently uses the dynamic sensor demonstrates a learning curve with its use, and an “attrition” curve once it is removed. Consistent sensor balance is more predictable with constant sensor use.
Introduction
Recent studies suggest that a balanced total knee arthroplasty (TKA) may lead to better functional outcomes and patient satisfaction [1-5]. Manual coronal plane balance has been achieved primarily through tactile feedback and visual cues. Whether a knee is “balanced” is subjective and is affected by various factors including surgeon training, experience, and surgical volume [6,7]. Furthermore, unlike joint alignment, cut angles, and magnitude of component rotation, there has not been a widely accepted metric for “balance.” Asymmetric radiographic joint space gapping is but one sign of gross extension space coronal imbalance. There are as yet no comparable markers for finer magnitudes of imbalance and imbalance at varying degrees of flexion. In recent years, dynamic sensors have played an increasing role in coronal plane balancing. These sensors display tibiofemoral contact points and measure load (or force) to provide real-time intraoperative feedback on whether the knee is truly “sensorbalanced”. Various authors suggest that sensor-balanced TKA may lead to improved patient satisfaction and patient-reported outcomes [1-5], improved survivorship, and a reduced need for revision [8].