Evaluation of long-term outcomes after anterior cruciate ligament reconstruction. Operative methods, clinical and radiological findings, and their relationship to patient-reported acceptable knee function

Abstract

The overarching theme of this thesis was to evaluate long-term clinical, subjective and radiological results after anterior cruciate ligament (ACL) reconstruction in regard to: different surgical methods, specifically anatomic single-bundle (SB) and double-bundle (DB) graft techniques (study II); changes in the Knee Osteoarthritis Outcome Score (KOOS) in mid- to long-term follow-up in relation to ACL injury with or without concomitant injuries (study I); tibial tunnel enlargement in anatomic SB and DB ACLR using biocomposite interference screws containing ß-tricalcium phosphate (ß-TCP) (study III); and the definition of the Patient Acceptable Symptom State (PASS) for the KOOS at 5-, 10- and 15- year follow-up in a Swedish population (Study IV). Study I demonstrated that patients with both concomitant meniscal and cartilage injuries reported worse KOOS scores at 10-year follow-up. Study II could not demonstrate any significant difference in any measure examined in the SB and DB ACLR methods. Study III showed 76% of SB patient radiographs did not reveal any tibial tunnel enlargement at 10-year followup compared to early postoperative images. This was the case in 69% of posterolateral (PL) tunnels and 63% of anteromedial tunnels in those participants that received DB ACLR. Study IV showed no change over time for PASS values for KOOS subscales, and that predictive modelling can reliably define PASS. The studies presented here demonstrated the largest depreciation in subjective outcomes via the KOOS at 10-year follow-up in those with concomitant meniscal and cartilage injuries when compared to 5-years previous, providing weight to the argument for performing ACLR before instability events cause concomitant injury; that there was no significant difference in rotational nor anteroposterior (AP) laxity between the SB and DB methods, with similar subjective and radiological OA measures, with the vast majority of radiographs from both cohorts not demonstrating any tunnel enlargement at 10-year follow-up. Finally, robust and reliable PASS cut-offs for the KOOS subscales were defined for 5-, 10- and 15- year follow-up in a Swedish population using a predictive modelling approach, demonstrating a lower PASS-Sports & Recreation cut-off than published data on an American -Norwegian population; suggesting it may not be possible to assume all populations adhere to the same PASS values for the KOOS.