Comparison of anterior knee laxity measurements recorded by manual versus mechanical arthrometers in ACL reconstruction patients at return to sport

Background

Arthrometers are devices used to evaluate knee laxity by quantifying anterior tibiofemoral displacement. The purpose of this study was to assess the congruence of tibiofemoral displacement measurements between manual and mechanical knee arthrometers in anterior cruciate ligament reconstructed (ACLR) patients.

Methods

This investigation evaluated 44 limbs in 22 subjects who underwent ACLR. All subjects were cleared for return to sport prior to enrollment. Participants underwent manual and mechanical arthrometer assessments of anterior knee laxity in the same visit. Both involved and uninvolved limbs were assessed. The magnitude of raw knee laxity measurements between arthrometers, inter-device associations, and rank-order significance of limb measurements were assessed. The impact of different post-operative training protocols on device measurements was also evaluated.

Results

Mean tibiofemoral displacement measurements for involved and uninvolved limbs were comparable for the mechanical arthrometer at 134 N and manual arthrometer at 89 N (P = 0.33), however, mean displacement values varied significantly between the two arthrometers at 134 N (P < 0.01). Overall, significant associations between mechanical and manual arthrometer measurements were not observed. Rank order trended toward lower difference when comparing Side and Device (P > 0.06). Consilience between mechanical and manual arthrometers was not observed in this investigation.

Conclusions

Multi-center studies or literature syntheses that incorporate more than one type of arthrometer should focus on reporting delta values as the present data demonstrated no significant repeated measures deltas between-devices.