Monitoring changes in knee surface morphology after anterior cruciate ligament reconstruction surgery using 3D surface scanning

Study design: Prospective case series. Background: After surgical reconstruction of the anterior cruciate ligament, recovery to pre-injury levels of knee function is challenging. Postoperative edema and muscle atrophy are common roadblocks to full function and are evident in changes to the surface morphology of the knee. There are currently few accessible objective tools to accurately track these morphological changes. Objectives: We aimed to determine if 3D surface scanning can be used to monitor changes in the external shape of the knee after surgery and throughout the rehabilitation process. Methods: Thirty participants had 3D surface scans taken of their knee, along with questionnaire-based functional outcomes prior to surgery (baseline), and at two-week, six-week, 12 week, and 26-week timepoints post-surgery. Volumetric changes relative to pre-op were assessed using generalized linear growth models for key anatomical regions and correlated with functional outcomes. Results: Significant swelling of the patella region compared to baseline was evident immediately after surgery (14%, p < 0.001), before returning to pre-operative levels. Changes in volume at this region were significantly associated with patient-reported functional outcomes. Reductions in volume of the regions corresponding to the vastus medialis and lateralis muscles were significant at 12 weeks post-surgery (p = 0.018 and 0.01 respectively) but returned to baseline levels at six months. Conclusion: We demonstrate the use of 3D surface scanning as a method for capturing detailed measurements of knee surface morphology after surgery. Significant changes in external morphology are evident during the rehabilitation process. (C) 2019 Elsevier B.V. All rights reserved.