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.

Detailed study description available in the published study protocol:

"The effect of targeted exercise on kneemuscle function in patients with persistent hamstring deficiency following ACL reconstruction - study protocol for a randomized controlled trial".

Bo Bregenhof1,3\* , Uffe Jørgensen1, Per Aagaard2, Nis Nissen3, Mark W. Creaby4, Jonas Bloch Thorlund2, Carsten Jensen3, Trine Torfing5 and Anders Holsgaard-Larsen1 Published: Trials. 2018; 19: 75. Published online 2018 Jan 26. doi: 10.1186/s13063-018-2448-3

Eligibility Criteria:
Inclusion Criteria:

* Age between 18-40 years,
* ACL-reconstructed using hamstring tendon auto-grafts, and a pathological defined between limb asymmetry ratio (operated/non-operated) of more than 10 % for maximal isometric strength of the knee flexors, at 1 year follow-up.

Exclusion Criteria:

* Other known pathology conditions in hip, knee, or ankle,
* BMI above 35, and
* Not understanding written Danish language.