Background Adequate neuromuscular control of the knee could be one element to prevent secondary injuries after an anterior cruciate ligament (ACL) injury. However, it is unclear which measurements should be used to assess neuromuscular control of the knee for a safe return to sports (RTS).

Objective To summarize assessments for neuromuscular control after an ACL injury to decide upon a safe RTS.

Design Systematic literature review, registered in PROSPERO (CRD42019122188).

Setting MEDLINE, EMBASE, CINAHL, Cochrane Library, SPORTDiscus, PEDro, and Web of Science were searched from inception to March 2019 and updated in November 2020. Risk of bias was assessed with a modified Downs & Black checklist.

Patients (or Participants) Male or female adults after an ACL injury, either treated surgically or conservatively. Time from injury until the assessment should be at least six months and the participants should have medical clearance for RTS.

Interventions (or Assessment of Risk Factors) Assessments for neuromuscular control in ACL-injured adults compared to the contralateral limb or healthy controls during dynamic activities.

Main Outcome Measurements Outcome measures describing neuromuscular control of lower limb muscles in domains of time, amplitude or activity related to electromyography (EMG).

Results From initially 1388 hits, a total of 38 mainly cross-sectional, case-controlled studies were included for qualitative analysis. Most studies provided surface EMG outcomes of thigh muscles during jumping, running or squatting. Outcomes measures described neuromuscular control of the knee in domains of time, amplitude or activity. Risk of bias was medium to high due to an unclear description of participants and prior interventions, confounding factors and incompletely reported results.

Conclusions Despite a wide range of EMG outcome measures for neuromuscular control, none was used to decide upon a safe RTS. Additional studies are needed to assess neuromuscular control in adult ACL patients to prevent secondary injuries.