Patient-reported Outcomes and Muscle Strength after a Physiotherapy-led Exercise and Support Brace Intervention in Patients with Acute Injury of the Posterior Cruciate Ligament: A Two-year Follow-up Study

BACKGROUND: While outcomes of posterior cruciate ligament (PCL) injuries treated surgically are well described, prospective studies reporting outcomes of exercise interventions are lacking. PURPOSE: The purpose of this study was to investigate changes in patient-reported outcomes of a physiotherapy-led exercise and support brace intervention in patients with acute injury of the PCL over a two-year follow-up period. Furthermore, this study sought to investigate changes in isometric knee muscle strength over an eight-month follow-up period, and finally to report conversion to surgical reconstruction over a two-year follow-up period. STUDY DESIGN: Case series study, prospective METHODS: Fifty patients with an acute injury of the PCL were treated with a brace and a physiotherapy-led exercise intervention and followed prospectively. Changes in patient-reported outcomes were measured with the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF) and the Knee injury and Osteoarthritis Outcome Score (KOOS) from baseline (diagnosis) to two-year follow-up. Furthermore, changes in isometric knee flexion and extension strength were measured with a static strength dynamometer from 16 weeks after diagnosis to one-year follow-up. Conversion to surgery was prospectively extracted from medical records. Mean changes were analyzed with a mixed effects model with time as a fixed factor. RESULTS: The IKDC-SKF score improved 28 (95%CI 24-33) IKDC points from baseline to two-year follow-up. Isometric knee flexion strength of the injured knee increased 0.18 (95%CI 0.11-0.25) Nm/kg from 16 weeks after diagnosis to one-year follow-up, corresponding to an increase of 16%. In contrast, isometric knee extension strength of the injured knee did not change (0.12 (95%CI 0.00-0.24) Nm/kg, p=0.042). Over two years, seven patients converted to PCL surgical reconstruction. One and two-year follow-up were completed by 46 and 31 patients, respectively. CONCLUSIONS: The physiotherapy-led exercise and support brace intervention demonstrated clinically relevant improvements in patient-reported outcomes and knee flexion strength, and the risk of PCL surgical reconstruction was considered low within the first two years. LEVEL OF EVIDENCE: 3b