Comparison of functional outcome after anterior cruciate ligament reconstruction resulting in low, normal and increased laxity

The aim of the study was to analyse and compare the results after arthroscopic anterior cruciate ligament (ACL) reconstruction using patellar tendon autografts in three groups of patients. The groups were determined by knee laxity as measured with the KT-1000 arthrometer at the follow-up two to five years after the reconstruction. Group A (n=15) had an anterior side-to-side laxity difference of <-3 mm (i.e. the reconstructed knee was less lax than the contralateral non-injured knee), Group B (n=376) had a difference of ≥-1, but ≤+2 mm and Group C (n=38) had a difference of 6 mm. All the patients had a normal contralateral knee. In Group A, 7115 (47%) patients and, in Group B, 82/375 (22%) patients had an extension deficit of ≥5° (P=0.052). The corresponding values in terms of flexion deficit were 8/15 (53%) and 99/375 (26%) respectively (P=0.04) (one missing value in Group B). In Group C, 14/38 (37%) had an extension deficit (P=0.04; Group B vs Group C). Group C displayed worse results than Group B in terms of the Lysholm score and the one-leg-hop test (P=0.001 and P=0.011 respectively). The corresponding comparison between Group A and Group B revealed no significant differences. We conclude that a considerable number of patients showed persisting deficits in range of motion (ROM) after an ACL reconstruction. No major differences were found if they were analysed in subgroups with decreased, near normal or with increased knee laxity. The worst residual functional impairment, as measured with the Lysholm score and one-leg-hop test, was found in the group with increased knee laxity and most ROM deficits in the knees with decreased laxity.