Combined ACL-PCL injuries predict poorer prognosis after MLKR: One-year results on work, sport, and muscle recovery.

Background: The prognosis of multi-ligament knee injury (MLKI) can be severe despite modern treatment approaches. It is influenced by the severity of associated damage, lesion pattern, and the course of pre-, peri-, and postoperative management.The aim of our study was to compare multiligament knee reconstruction (MLKR) cases involving both the ACL and PCL with those involving either the ACL or PCL in terms of one-year postoperative outcomes. Additionally, we assessed factors influencing outcomes at one year, functional and clinical results, as well as return to work (RTW) and return to sport (RTS) at the one-year follow-up.

Hypothesis: We hypothesized that MLKR cases involving both the ACL and PCL would lead to poorer outcomes compared to those involving only one of the cruciate ligaments.

Methods: Seventy-two patients were included in the study between October 2019 and April 2023. Diagnosis was based on a 3 T MRI combined with clinical examination, and MLKI was classified according to the five-level Schenck classification. Anatomical ligament reconstruction was performed, followed by a structured postoperative physiotherapy program in a specialized reference center. Functional outcomes were assessed using IKDC, KOOS, and Tegner, along with isokinetic muscle strength testing (quadriceps, hamstrings), VAS pain scores, and return to sport and work at the one-year follow-up. IKDC and KOOS scores were compared between patients with a single cruciate ligament injury (Schenck I) and those with both cruciate ligaments involved (Schenck > I). A multivariate analysis was conducted to identify factors associated with poor outcomes at one year postoperatively.

Results: Patients with only one cruciate ligament involved in the MLKR had better IKDC and KOOS at one-year post- operative in comparison with patients with both cruciate ligaments involved (p < 0.05). Age has a negative correlation with KOOS and IKDC (p < 0.05), Tegner has a positive correlation with KOOS (p < 0.05). All patients had a strength deficit in quadriceps and hamstring contraction at one-year post-operative compared to the uninjured knee. Mean KOOS was 72.1 ± 20.1 [19;100], mean IKDC was 71.1 ± 19.9 [18;95.4] and mean VAS was 1.6 ± 1.9 [0;8]. Return to work was observed in 89% (n = 64), and 76.4% (n = 55) returned to sports.

Conclusion: Combined injuries involving both the ACL and PCL are associated with a poorer prognosis compared to isolated injuries of either ligament. At one-year follow-up, MLKR allows most patients to return to work; however, return to physical activity remains more uncertain. Residual strength deficits persist in both the quadriceps and hamstring muscles.

Level of evidence: III; Retrospective comparative study.