Patients with knee hyperextension who regained preoperative range of motion after ACL reconstruction have worse knee stability but better subjective outcomes than patients who did not regained preoperative range of motion

Abstract

Objectives To evaluate patients submitted to ACL reconstruction with preoperative hyperextension and compare patients who recovered the entire range of motion with patients who recovered full extension but not hyperextension. Methods Patients submitted to surgery from June 2013 to June 2021 were evaluated. Patients aged 18 to 60 years with acute or chronic ACL injuries submitted to anatomical ACL reconstruction with a single bundle and any graft with at least 24 months of follow-up were included. The following data were collected: age, sex, time from injury to surgery, passive knee hyperextension, pre-and postoperative KT-1000 arthrometer laxity and pivot-shift, associated meniscal injury and treatment (meniscectomy or repair), type of graft used, intra-articular graft diameter, associated extra-articular procedure, follow-up time, and postoperative Lysholm Knee Scoring Scale and International Knee Documentation Committee (IKDC) subjective scores. Results Among 225 patients evaluated, 48 (21.3%) did not recover preoperative hyperextension, and 177 recovered range of motion. Regarding the pre-and intraoperative variables, there was no difference between the groups, except that who did not recover hyperextension had a larger diameter graft than patients who recovered hyperextension (8.7 ± 0.7 vs. 8.3 ± 0.7; p = 0.018). Regarding the postoperative variables evaluated, patients who recovered the preoperative hyperextension showed improvement on all scales evaluated compared to patients who did not recover the range of motion. However, patients who recovered hyperextension showed more laxity on physical examination, measured by the KT-1000 and the pivot-shift. Conclusion Patients with knee hyperextension greater than 5 degrees who regained preoperative range of motion after ACL reconstruction have worse knee stability according to KT-1000 and pivot-shift tests than patients who regained full extension but not hyperextension. However, patients who recover full range of motion show improvement on all subjective function scales.