Unilateral lower limb injury: Its long-term effects on quadriceps, hamstring, and plantarflexor muscle strength

Objective: To ascertain if long-term deficits in quadriceps, hamstring, and plantarflexor muscle strength remain after unilateral lower-limb musculoskeletal injury and to quantify whether improvements in performance continue once a subject concludes rehabilitation and returns to everyday activities. The relation between the size of decrement and limb dominance, type of injury, and time since injury was also considered. Design: Isometric and/or dynamic muscle strength of both legs was measured (using the KinCom 500H isokinetic dynamometer) in 48 subjects. Setting: A physiological laboratory at Brunel University. Patients: Patients were recruited locally via a district general hospital, sports injury clinic, and university. Main Outcome Measures: Muscle strength in the injured limb, reported as a percentage of muscle strength in the uninjured limb. It was assumed that the preinjury state of the injured limb was similar to that of the uninjured limb. Results: Decrements were seen in mean isometric and peak isometric, concentric, and eccentric quadriceps activity (p <.0001) and isometric plantarflexor activity (p <.05) in the injured limb, with the type of injury influencing the size of the decrement. Minimal difference was found in the hamstring muscles. Conclusions: The decrements in performance in the quadriceps muscle imply that full recovery las defined by the preinjury state) is frequently not achieved and stress the need for accurate, objective assessment of muscle strength and further investigation into the nature and duration of rehabilitation after musculoskeletal injury. (C) 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.