Background

ACL suture repair techniques (ACLrep) has been subject to a renewed interest in the recent years. Although several clinical studies have yielded good short-term results, high quality evidence is lacking in regard to the effectiveness of this treatment compered eth ACL reconstruction (ACLrec). Moreover, it is nowadays well accepted that anterolateral ligament (ALL) contributes to anterolateral (AL) rotational instability in the ACL deficient knee. Lateral extra-articular tenodesis (LET), used in addition to ACLrec, have shown to improve knee stability and reduce rate of failure.

PURPOSE/HYPOTHESIS
To assess the 2 years patients-reported outcomes (PROMs) and instrumented anteroposterior (AP) knee laxity with arthrometer KT-1000 2 years after surgery of combined ACL and ALL repair as compared with a standard ACLRec + LET.
The hypothesis of this study is that in an acute AL knee instability resulting from a combined proximal ACL tears and ALL injury in adults, repair is not inferior to a standard ACL reconstruction and LET at 2 years.

Methods

Patients with acute severe AL instability (ACL + ALL tears) who underwent early ACL surgery (injury-surgery interval < 14 days) were prospectively enrolled in the study for a total of 58 patients.
ACL tears were graded according to Sherman classification in 4 types.
Patients with a proximal tear (type 1 and 2) were assigned to receive ACLrep (n= 37) while patients with type 3 and 4 and fair tissue quality (n=21) were assigned to receive ACLrec with DGST + LET.
Repair consisted in a trans-osseus pull out suture of the tibial remnant over the anatomic origin of the ACL augmented with direct repair of the ALL. Reconstruction consisted in a standard DGST ACL reconstruction plus a Macintosh modified lateral tenodesis.

PROMs included International Knee Documentation Committee (IKDC), Tegner Lysholm Knee Scoring Scale (TLKSS), Knee Injury and Osteoarthritis Outcome (KOOS), and instrumented anteroposterior (AP) knee laxity evaluation with KT-1000 at 2 years of follow-up.

Results

A sample size calculation demonstrated the need for 21 patients in each group for a Power of 95% (with a 95% CI) to show the noninferiority of the repair group considering at least +1,5 of arthrometric side-to-side difference. Patients in the ACLrep group showed better results in all scales: mean IKDC was 95,51±52,4 respect to 86,92±13,92 (p=0,02); mean koos was 97,49±2,71 respect to 93,50±7,05 (p=0,009); mean TLKSS was 96,98±5,14 respect to 91,69±10,08 (p=0,02);
The mean arthrometric side-to-side differences with KT-1000 showed no differences (ACLrep: 1,70±1,02; ACLrec: 2,21±0,80; p=0,11). The unilateral 95% CI for side-to-side differences in ACLrep was 1,7 (to 2,02) (< to 3,01 limits for noninferiority) and in ACLrec was 2,21 (to 2,46), p=0,147. Hence, there are non-statistically differences between the two groups according to the arthrometric side-to-side differences and the noninferiority was proven.

Conclusions

In acute anterolateral instability resulting from a combined injury of ACL and ALL direct repair is noninferior in PROMs and knee laxity when compared with standard ACLrec plus LET at 2 year of follow-up.