There is increasing evidence that patients with ACL reconstruction using ipsilateral graft harvest are at greater risk of rupture (12.5%) on their contralateral compared to their surgical side (7.9%). The purpose of this study is to re-evaluate patients from a previous study comparing ipsi- versus contralateral graft harvest to compare ACL rupture rate at a minimum 10 year follow-up.

An attempt to contact all participants from a previously published study was made to invite them to return for a follow-up. The assessment included an International Knee Documentation Committee Knee Clinical Assessment (IKDC), isokinetic concentric knee flexion and extension strength testing, as well as the ACL-Quality of life (ACL-QOL). A chart review was conducted to identify or confirm subsequent ipsi- or contralateral knee surgeries.

In patients with ipsilateral graft, 3/34 (8.8%) re-ruptured and 3/34 (8.8%) had contralateral rupture. In the contralateral group, 1/28 (3.6%) re-ruptured and 2/28 (7.1%) had contralateral rupture. The relative risk (RR) of re-rupture with ipsilateral graft was 2.47 compared to using the contralateral site (p=0.42). RR of rupture on the contralateral side when ipsilateral graft was used was 1.23 compared to the alternate approach. Current contact information was unavailable for 21 patients. Of the 47 remaining, 37 were consented (79%). No difference in the ACL-QOL between groups (ipsilateral 68.4±24.4, contralateral 80.1±16.0, p=0.17) was observed. There were no differences in knee flexion strength between groups (peak torque flexion affected leg: ipsilateral 77.8nm/kg±27.4, contralateral: 90.0 nm/kg±35.1; p=0.32; Unaffected leg: ipsilateral: 83.3 nm/kg±30.2 contralateral 81.7 nm/kg±24.4; p= 0.89).

This study suggests that using the contralateral hamstring in ACL rupture is not associated with an increase in ACL rupture on either side. The risk of ACL injury was low in all limbs; therefore, a larger study would be required to definitively state that graft side had no impact.

C-Arm fluoroscopy is limited by its 2D imaging modality and is incapable of providing accurate 3D quantitative assessment of operative anatomy. In High Tibial Osteotomy (HTO), assessing the distance between the mechanical axis of the leg and the centre of the knee joint is difficult to accomplish due to limited fluoroscopic view size. A previously developed sensor-based tracking system (TC-Arm)adds on to C-arm equipment to provide additional quantitative capabilities. A new image-based tracking module was developed for TC-Arm using a reference panel with an array of fiducial markers. The image analysis software segments the marker positions in each image and identifies image coordinates with respect to the panel. Each image's parameters are identified by 2D-3D matching of the panel's 3D model to the marker's epipolar geometries. Finally, the defined linear transformation matrices are applied for positioning all the fluoroscopic images with respect to the same global reference. A Sawbone model of the leg was used as a phantom and marked with radio-dense fiducial markers at the centres of each joint.

An Optotrak optoelectronic tracking system data was used to validate the new module's functions. First, tracking accuracy was determined by comparing orthogonal-stereo views and the reconstructed positions of the panel's design. Secondly, TC-Arm's results were compared to the corresponding digitised references points on the Sawbone model to calculate errors in the varus/valgus angle and mechanical axis deviation. The new addition to the TC-Arm has a reasonable tracking accuracy (<3.6mm, <4°) considering HTO: The system measured the mechanical axis deviation for HTO application with an accuracy of 1.3 mm and 1.4°. Comparing these results with the acceptable tolerance of less than 10 mm for MAD reported in the literature, our demonstrated results are considered to be within an acceptable range. With the new module, the capability for three-dimensional quantitative assessments of operative anatomies of any size can be added to any C-arm equipment in the OR. This can have great potential for many complex orthopaedic trauma, reconstruction, or preservation surgeries including HTO.