Staying within the Envelope of Function: Both Joint Overloading and Under Loading can be Detrimental to Cartilage Health Early after Acl Reconstruction
Abstract:
Purpose: Under/over-loading following anterior cruciate ligament reconstruction (ACLR) have been reported to affect postoperative cartilage. Conflicting rehabilitation programs promote joint loading at different time points. The purpose of this review was to determine whetherunder/overloading is associated with imaging/biochemical biomarkers of cartilage degradation after ACLR and whether these associations are time-dependent.
Methods: PubMed literature search was conducted identifying ACL-reconstructed patients, knee joint moments/ vertical ground reaction forces, and imaging or biochemical biomarkers of cartilage degeneration. Initial search produced 357 publications. Fifteen studies (510 patients) published between 2016-2021 satisfied inclusion crite ria. Method of cartilage degeneration measurement, whether under/over-loading was associated with cartilage degradation, and time points were assessed.
Results: Three studies reported underloading, while two studies reported overloading, was associated with car tilage degradation. Between 18-months and 8-years after ACLR, overloading was consistently associated with degenerative cartilage changes on MRI/ultrasound (7/7 studies). Two studies reported under-loading two years or later after ACLR was associated with increased plasma bio markers of cartilage degradation. While underloading compared to the contralateral limb was associated with serum/plasma cartilage biomarkers at later time-points, it remains unclear if systemic biomarkers are evidence of increased cartilage remodeling in the involved or uninvolved limb.
Conclusion: Under/over-loading 6-months after ACLR were associated with biomarkers of cartilage degradation, whereas overloading was more consistently associated with imaging biomarkers of cartilage changes 18-months after ACLR. The ineffectively-rehabilitated knee continues to threaten joint health, and current results suggest re habilitation strategies are needed 28 to promote optimal early postoperative loading while avoiding overloading 18 months after ACLR.
