Can Targeted Exercise Improve Knee Strength Following ACLR (RATE)

Anterior cruciate ligament reconstruction (ACLR) is high volume surgery, carried out in about 2800 patients annually in Denmark per year. ACLR patients (using hamstring auto-graft) have persistent hamstring strength deficiency when evaluated more than 1-2 years after ACL-reconstruction. The investigators have designed this randomized controlled trial (RCT) with the main purpose to investigate the effect of a targeted muscle strength exercise intervention on the neuromuscular rehabilitation of ACLR-patients compared with 'care-as- usual'.

The study is designed as a prospective, superiority, parallel-group with balanced randomization (1:1) RCT (Level of evidence: II) with blinded allocation, and outcome assessment according to the CONSORT statement (Consolidated Standards of Reporting Trials). 50 patients with ACL reconstruction and persistent hamstring muscle deficiency, will be recruited at the outpatient clinic 1-year follow-up, and allocated to one of two 12 weeks' interventions, either a) the supervised progressive strength and neuromuscular exercise group (SNG) with supervised training twice weekly. Or b) the control group (CON) receiving patient education based on a home-based exercise regime of low intensity, defined as 'care as usual'. Outcome measures include, maximal isometric knee flexor muscle strength (primary outcome), knee extensor strength, and the Knee injury and Osteoarthritis Outcome Score (KOOS) (secondary outcomes). In addition, the following explorative outcomes will be investigated; hamstring to quadriceps strength ratios, the International Knee Documentation Committee Subjective Knee Form (IKDC), magnetic resonance imaging (MRI) to evaluate tendon regeneration of the hamstrings and finally kinetic/kinematic biomechanical outcomes of knee related functional tasks.

To the investigators knowledge, this is the first RCT to investigate the efficacy of combined progressive resistance training and neuromuscular exercise in the late rehabilitation phase in patients demonstrating persistent limb-to-limb knee muscle asymmetry following ACLR. Reduced hamstring strength represents a potential risk factor for secondary ligament rupture and accelerated progression of osteoarthritis (OA). If deemed effective, the intervention paradigm introduced in this study may help to improve current treatment strategies.