Summary

The ACLISS allows to easily and rapidly identify different injury severity profiles in primary ACLR. Injury severity was associated with an increased involvement of the medial tibiofemoral compartment. The ACLISS is convenient to use in daily clinical practice and represents a feasible grading and documentation tool for a reproducible comparison of clinical data in ACL injured patients.

Abstract

Purpose

To describe the magnitude of structural tissue damage occurring in patients with a primary ACL injury by developing a semiquantitative score, the ACL Injury Severity Scale (ACLISS). It was hypothesized that the ACLISS would provide an easy description and categorization of a wide spectrum of injuries, reaching from isolated ACL tears to ACL injuries with a complex association of structural tissue damage.

Methods

A stepwise approach was used by selecting a series of individual items of associated structural tissue damage parameters. The eligibility of each item within the score was based on a literature search and a consensus between the authors after considering the diagnostic modalities and clinical importance of associated injuries to the menisci, subchondral bone, articular cartilage or collateral ligaments. Then, a retrospective analysis of associated injuries was performed in a series of 100 patients with primary ACLR by a single surgeon. The following exclusion criteria were applied: skeletal immaturity, revision ACLR and realignment procedures or multiligament reconstructions, previous knee surgeries, time from ACL injury to MRI > 8 weeks. Analysis of associated injuries was based on acute preoperative MRI and intraoperative arthroscopic findings. The number of items was then reduced depending on their prevalence as well as to avoid a floor or ceiling effect in the final score. Finally, an analysis of the overall scale distribution was performed to classify the patients according to different injury profiles.

Results

100 patients with a primary ACLR were included (58 males/42 females, median age at surgery 26 (22–32), median BMI 23.4 (21.7–25.8), 46 left/54 right knees). The median time from injury to MRI was of 9 days (4–23). The median time from injury to ACLR was 99 days (48–200). A final scoring system of 12 points was developed (12 = highest severity). Six points were attributed to injuries of the medial and lateral tibiofemoral compartment respectively. The number of associated injuries increased with ACLISS grading. The median scale value was 4.5 (lower quartile 3.0; higher quartile 7.0). Based on these quartiles, a score < 4 was considered to be an injury of mild severity (grade I), a score between≥4 and≤7 was defined as moderately severe (grade II) and a score>7 displayed the most severe cases of ACL injuries (grade III). The knees were graded ACLISS I in 35%, ACLISS II in 49% and ACLISS III in 16% of patients. Overall, damage to the lateral tibiofemoral compartment was predominant (p < 0.01), but a proportional increase of tissue damage could be observed in the medial tibiofemoral compartment with the severity of ACLISS grading (p < 0.01).

Conclusions

MRI and arthroscopic assessment of ACL-associated structural tissue damage allowed to develop a documentation tool, which easily and rapidly identified 3 different injury severity profiles (ACLISS I to III) in patients with primary ACLR. Although injuries were overall more frequent in the lateral tibiofemoral compartment, injury severity was associated with a higher involvement of the medial compartment. The ACLISS is convenient to use in daily clinical practice and represents a feasible grading and documentation tool allowing for a reproducible comparison of clinical data in ACL injured patients.