The Utility of Continuous Passive Motion After Anterior Cruciate Ligament Reconstruction: A Systematic Review of Comparative Studies

BACKGROUND: The application of continuous passive motion (CPM) after anterior cruciate ligament reconstruction (ACLR) was popularized in the 1990s, but advancements in the understanding of ACLR rehabilitation have made the application of CPM controversial. Many sports medicine fellowship-trained surgeons report using CPM machines postoperatively. PURPOSE: To determine the efficacy of CPM use for recovery after ACLR with respect to knee range of motion (ROM), knee swelling, postoperative pain, and postoperative complications. STUDY DESIGN: Systematic review; Level of evidence, 3. METHODS: The PubMed (MEDLINE), EMBASE, Cochrane, Cumulative Index of Nursing, and Allied Health Literature databases were searched from inception to January 1, 2020, for studies with evidence levels 1 to 3 on the use of CPM for ACLR rehabilitation. Included studies were those that comparatively evaluated postoperative outcomes after ACLR between at least 2 groups of patients, with 1 having received CPM rehabilitation and the other not having received CPM. RESULTS: A total of 12 studies from 1989 to 2019 met the inclusion criteria. These studies included 808 patients who underwent ACLR. There was no evidence of CPM improving knee stability, final postoperative ROM, or subjective pain scores. Additionally, CPM did not lead to decreased muscle atrophy or improved International Knee Documentation Committee scores. Regarding pain medication intake during postoperative hospitalization, 2 studies found that the CPM group used less pain medication, 1 study found the CPM group used more pain medication, and 1 study found that there was no difference between the 2 groups. Complications varied widely, with 2 of 12 studies reporting complications that required a return to the operating room. CONCLUSION: A clinical benefit of postoperative CPM use after ACLR was not identified in this review. While our systematic review identified a number of studies that suggest CPM use may be associated with lower usage of pain medication in hospitalized patients, this cannot be confirmed without further investigation with standardized CPM protocols and larger sample sizes. Routine CPM use after ACLR was not supported by this systematic review.