Summary

This study brings attention to the potential for a high rate of soft tissue interposition especially for overweight patients. The study identified a protocol and technique for proper ALS deployment

Abstract

Background

During multiligament knee reconstructions, grafts can be fixed by interference screw, cross-pin, or suspensory fixation, in order to achieve graft tension. Interference screw fixation (IS) is the most common method of graft fixation, but does not allow for graft tension adjustments once a graft is secure. Establishing a graft tensioning sequence for multiligament knee injuries is challenging because of the multiple planes of laxity encountered and debate exists as to the best graft tensioning sequence. Adjustable loop suspensory (ALS) fixation offers the ability to re-tension grafts and potentially minimizes the importance of committing to an established tension order. One of the most frequently reported complications of adjustable loop fixation is improper deployment of the fixation leaving soft tissue interposed between the button and bone. Tissue interposition can lead to tissue irritation. This study aims to investigate the rates of soft tissue irritation associated with ALS fixation in a large clinical cohort of patients where ALS fixation was used. Additional clinical, radiographic, and patient-reported outcomes will also be reported.

Methods

A retrospective review of radiographic, clinical, and patient-reported outcomes following knee ligament reconstruction from a Level 1 trauma centre was completed. Inclusion criteria were patients 18 years or older undergoing ACL, PCL, MCL, and/or LCL reconstruction using ALS fixation for a least one end of the graft, with a minimum of six-month post-operative follow-up. Knee dislocations (KD) were classified using the Schenck Classification. The primary outcome measure was implant removal rate. Secondary outcomes were rates of revision surgery, deep infection, soft tissue interposition, radiographic laxity, radiographic malposition, clinical laxity, and Lysholm and Tegner scores. Descriptive statistics were used and comparisons between those with and without radiographic malposition of the device were compared using independent samples t-test.

Results

Sixty-one patients (mean age = 34.1 +/- 10.2 years; 67.7% male) were included. A total of 266 ALS fixation were included. Median follow-up duration was 270.5 (range = 117 to 953) days. Most injuries were KD type III. Intraosseous deployment occurred in 1.5% of ALS fixation (6.6% of cases) and 3.3% of ALS fixation (14.8% cases) had implants secured in soft tissue, rather than directly on bone. However, the implant removal rate was only 6.6% (n = 4). The majority of those who met radiographic criteria for soft tissue interposition 45.5% were considered overweight (BMI >25), while 90.9% were considered obese (BMI >30). Graft revision surgery rate was 1.6% (n = 1). Stress radiographs demonstrated the following median side to side difference: PCL 1.55 mm (0-15) MCL 1.55 mm (0-5.1) and LCL 0 (0-2.8). Mean Lysholm and Tegner scores were 82.8 (SD = 13.5) and 4.8 (SD = 2.1), respectively.

Conclusion

This study brings attention to the potential for a high rate of soft tissue interposition especially for overweight patients. However, adjustable loop suspensory fixation demonstrates a low revision surgery rate, a high rate of implant retention, excellent radiographic stability, and patient-reported outcome scores. Additionally, the study identified a protocol and technique for ALS deployment that eliminated the occurrence of soft tissue interposition.