Traction during Total Knee Arthroplasty leads to a Bone-Conserving Tibial Resection. A Retrospective Comparative Study

Abstract

Objective. In Total Knee Arthroplasty, an insert is selected to give optimal movement and stability. The depth of tibial resection is the major influence on insert thickness. A deep resection has drawbacks: it may destabilise the posterior cruciate insertion, the cut may not be through strong subchondral bone, and inserts up to 20mm must be available. In-line traction has been used in some centres to select the resection depth, but has not been described. This paper compares the depth of resection achieved with stylus technique against manual in-line traction technique using the spacer block.

Methods. Retrospective comparative study. 70 'Stylus' cases versus 70 'Traction' cases. Insert thickness utilised as a surrogate of the depth of resection. Numbers of inserts used of each thickness, and data about potential confounding factors, retrieved from e-record. Wilcoxon rank-sum test for increase / decrease in the median insert thickness for 'Traction' compared to 'Stylus'. Observations made on limb alignment, joint line obliquity and kinematic resurfacing.

Results. 'Traction' (median 8mm) gives a more bone-conserving cut than 'Stylus' (median 10mm)(p=0.013). Numbers of inserts implanted (Stylus, Traction): Tibial re-cut (6,6); 8mm insert (23,39); 10mm insert (26,18); 12.5mm insert (13,7); 15mm insert (2,0).

Discussion and Conclusion. Study findings suggest in-line traction can reference from the distal femoral cut, appropriately tensioning the capsule and ligaments, to give a bone-conserving tibial cut. The technique can be used with existing instruments. Further investigation is proposed into limb alignment: specifically, intra-operative traction as a complement to kinematic resurfacing of the femur.