Summary

LEAT does not affect ACL graft healing but does reduce post operative femoral and tibial tunnel widening at one year post surgery

Abstract

Objectives
Lateral extra-articular tenodesis (LEAT) is a well-established technique used to reduce re-injury after ACL reconstruction (ACLR). LEAT is utilized to reduce anterolateral rotatory instability and protect the ACL graft. Biomechanical studies have revealed LEAT significantly reduces intra-articular forces across the ACL graft and affects overall knee biomechanics. We hypothesized that LEAT could improve graft healing, or conversely stress shield it and impair healing. We aimed to assess graft healing in patients who underwent ACLR versus those who underwent ACLR+LEAT using a previously standardized MRI protocol at one-year post-surgery.

Methods

A matched cohort comparison was performed on patients who underwent ACLR with and without the addition of the LEAT. 40 patients were included in each group and matched for age, sex, body mass index, and reamed tunnel diameter. All ACLRs were single bundle quadrupled hamstring grafts with suspensory fixation on the femur and tibia. All ACLR+LEAT surgeries were using a modified deep Lemaire technique with a PEEK screw fixation to the lateral femoral condyle. No revision ACLRs or meniscectomies were included. Patients underwent a standardized rehabilitation protocol. 12 months post-surgery, patients underwent a standardized 3T MRI scan utilizing a validated protocol which included volumetric and near isotropic (0.5mm x0.5mm x 0.65mm) turbo spin echo sequences optimized for graft assessment. MRI analysis was performed on 3 x20-mm2 regions of interest on the graft (proximal, middle, and distal) using oblique reconstructions parallel and perpendicular to the graft. The Signal Noise Quotient (SNQ) was calculated with the formula SNQ= graft signal-PCL signal/background signal. Tunnel aperture signal and areas were also measured using multi planar reformation. Tunnel widening was evaluated by determining the difference between the initial intra-operative drilled tunnel diameter and the MRI measured tunnel diameters.
Patient reported outcomes were measured pre-injury and at 12 months post-surgery. Post operative side to side anterior laxity was determined using and Genourob arthrometer.

Results

The mean age was 18.6±3.74 in the ACLR+LEAT group and 18.6±3.95 in the ACLR group (P>0.05). The average preoperative BMI was 21.95±8.15 in the ACLR+LEAT group and 23.89±3.23 in the ACLR group (P>0.05). Mean femoral tunnel widening in the ACLR +LEAT group was 3.4±1.2 mm2 and 4.7±1.1 in the ACLR group (P=<0.05). Mean tibial tunnel widening in the ACLR +LEAT group was 2.7±1.1 mm2 and 4.0±0.9 in the ACLR group (P=<0.05). The mean adjusted graft SNQ was 9.0±14.9 in the ACLR+LEAT group and 9.5±11.4 in the ACLR group (P>0.05). No significant difference in clinical outcome scores and laxity were noted.

Conclusion

One year post-operatively we noted significantly less femoral and tibial tunnel widening in the ACLR+LEAT group. LEAT procedures have been shown to increase constraint of the knee, particularly reducing internal rotation of the tibia possibly reducing the phenomenon of tunnel widening. LEAT does not seem to effect ACL graft healing as graft healing was not statistically different in either group.