Summary

ACL-PCL ligament reconstruction associated with medial or lateral instability has 9.6 time higher risk of failure.

Abstract

Objectives
Multiple Ligament Knee Injuries (MLKI) are as rare as possibly devastating condition. Of these, bi-cruciate (Anterior Cruciate Ligament – ACL; Posterior Cruciate Ligament – PCL) injuries is often associated with medial and/or lateral structures involvement representing one of the most severe situations. A crucial topic to be investigated is the likelihood for patients to undergo further surgical procedures and which are the correlated risk factors.
Hence the purpose of the present study was to assess the survival rate and associated risk factors of a wide cohort of patient’s underwent surgical treatment for PCL based MLKI at long term-follow-up.

Methods

The institutional database was retrospectively searched for patients who underwent isolated and/or combined PCL reconstruction between January 2000 and December 2019.
Medical charts were reviewed to collect patients’ information, anamnesis, surgical data. All the patients were contacted to assess the occurrence of further surgical procedures.
Survival analysis was performed via the Kaplan-Meier method with surgical failure (re-operation to one of the reconstructed ligaments) as endpoint. The mean estimated survival time was calculated for the entire cohort, furthermore, the survivorship of ACL-PCL-MCL and ACL-PCL-PLC and of up to two ligaments reconstructed and more than two ligaments reconstructed was compared. The log-rank test with hazard ratio was calculated, with p<0.05 set as level of statistical significance. A logistic regression was also performed by using sex, BMI (=25 vs >25), age at surgery, limb, presence of cartilage lesions, diabetes, smoke, meniscal lesion as independent variables.

Results

A total of 42 patients fulfilled the inclusion criteria and were included in the analysis. The mean follow-up time was 9.6±5.6 years [range 1.3 – 28.0]. Six patients (14.3%) underwent reoperation and were considered as surgical failures. The survivorship was 95.2%, 92.6%, 87.1%, and 74.7% at 2, 5, 12, and 15 years, respectively. The survivorship in patient undergoing more than two ligaments’ reconstructions (ACL-PCL-PMC or ACL-PCL-PLC) was significantly lower than patients undergoing one or two reconstructions (15.4 years [10.5 – 20.3] vs 25.2 years [18.3 – 32.1], p=0.019). No survival differences were found between the ACL-PCL-PMC and the ACL-PCL-PLC (p=0.063). No significant outcome interaction emerged from the multiple regression analysis (p=0.069).

Discussion

The most important finding of the present study was that bi-cruciate ligament reconstruction associated with medial or lateral instability is burdened by a higher risk of failure.
Overall, more than 92% of reconstructed knees still were revision-free at 5 years follow-up, and only after the first decades these patients underwent a revision of at least one ligament previously reconstructed, with a relevant drop at 15 years.
The clinical relevance derives from the deepening of the knowledge into the MLKI; in particular, regarding the need of further surgical major procedures which can help the surgeon to set patient’s expectations in these complex scenarios.