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 musculosk eletal 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 inj ury, 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 p ercentage 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 l imb. Results: Decrements were seen in mean isometric and peak isometric, concent ric, and eccentric quadriceps activity (p <.0001) and isometric plantarflex or activity (p <.05) in the injured limb, with the type of injury influenci ng the size of the decrement. Minimal difference was found in the hamstring muscles. Conclusions: The decrements in performance in the quadriceps muscle imply t hat full recovery las defined by the preinjury state) is frequently not ach ieved and stress the need for accurate, objective assessment of muscle stre ngth and further investigation into the nature and duration of rehabilitati on after musculoskeletal injury. (C) 1999 by the American Congress of Rehab ilitation Medicine and the American Academy of Physical Medicine and Rehabi litation.