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General Orthopaedics

INTERNAL MALROTATION OF THE TIBIAL COMPONENT IS A CAUSE OF FLEXION CONTRACTURE AFTER TOTAL KNEE ARTHROPLASTY: IN VIVO STUDY

The International Society for Technology in Arthroplasty (ISTA), 30th Annual Congress, Seoul, South Korea, September 2017. Part 2 of 2.



Abstract

Introduction

Stiffness post Total Knee Replacement (TKR) is a common, complex and multifactorial problem. Many reports claim that component mal-rotation plays an important role in this problem. Internal mal-rotation of the tibial component is underestimated among surgeons when compared to femoral internal mal-rotation. We believe the internal mal-rotation of the tibial component can negatively affect the full extension of Knee. We performed an in-vivo study of the impact of tibial internal mal-rotation on knee extension in 31 cases.

Method

During TKR, once all bony cuts were completed and flexion/extension gaps balanced, we assessed the degree of knee extension using the trial component in the setting of normal tibial rotation and with varying degrees of internal rotation (13–33°, mean 21.2±4.6°). Intra-operative lateral knee X-ray was done to measure the degree of flexion contracture in both groups. We also compared the degree of flexion contracture between CR and PS spacers.

Results

The average degree of knee flexion contracture with normal rotation of the tibial component was 0.7±4.1° (range: −9 to 10), whereas after tibial internal rotation was 7.3±4.6° (range: −1 to 23) (P – value:0.001). The increase in the flexion contracture deformity was higher with PS spacer (7.18±2.61) than with CR spacers (5.22±2.05)

Conclusion

The internal mal-rotation of the tibial component limits the ability of the tibia to externally rotate on the femur, thereby limiting full knee extension and leading to flexion contracture.


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