Is the Use of Spreaders an Accurate Method for Ligament Balancing?

Abstract

Background: To analyze 2 methods of manual spreader gap assessment accuracy, visual vs blinded, compared with a controlled tensioner in total knee arthroplasty.

Methods: Twenty-two fresh frozen cadaver knees were used to perform total knee arthroplasty by 22 surgeons. Extension and flexion gaps were measured with empirical manual force application with spreaders in 2 different manners: (1) surgeons were blinded to gap geometry formation-blind method group (BM) and (2) surgeons viewed them-viewing method group (VM). A tensioner was used to measure the corresponding ligament tension applied during spreader measurements and to measure the extension and flexion gaps with standard force of 100 and 80 N (tensioner method [TM]) in each femorotibial compartment.

Results: All measurements with spreaders (VM and BM) presented extension and flexion gaps oversized and asymmetric (P < .0001), when compared with the same gaps measured with the tensioner. Approximately 63% (P = <0.001) and 77.3% (P = .161) of the VM group and 68.2% (P = .018) and 77.3% (P = .161) of the BM group demonstrated asymmetry for extension and flexion gaps up to 3 mm to the TM. Gaps measured in the VM group presented results with slightly less oversizing and asymmetries than the measurements in the BM group compared with TM, although significantly different (P < .0001).

Conclusion: The assessment of extension and flexion gaps with empirical manual applied force spreaders produced oversized and asymmetric gaps compared with the use of tensioner. No visual influence was observed during the spreader applied empirical manual force compared with the blinded assessment.

Keywords: arthroplasty; gap balance; knee; soft tissue balance; subvastus; tension.