Post-traumatic joint contracture (PTJC) is a debilitating condition, particularly in the elbow. Previously, we established an animal model of elbow PTJC quantifying passive postmortem joint mechanics and histological changes temporally. These results showed persistent motion loss similar to what is experienced in humans. Functional assessment of PTJC in our model was not previously considered; however, these measures would provide a clinically relevant measure and would further validate our model by demonstrating persistently altered joint function. To this end, a custom bilateral grip strength device was developed, and a recently established open-source gait analysis system was used to quantify forelimb function in our unilateral injury model. In vivo joint function was shown to be altered long-term and never fully recover. Specifically, forelimb strength in the injured limbs showed persistent deficits at all time points; additionally, gait patterns remained imbalanced and asymmetric throughout the study (although a few gait parameters did return to near normal levels). A quantitative understanding of these longitudinal, functional disabilities further strengthens the clinical relevance of our rat PTJC model enabling assessment of the effectiveness of future interventions aimed at reducing or preventing PTJC.

Background. Post-traumatic joint contracture (PTJC), characterized by loss of motion and permanent stiffness, affects up to 50% of patients following elbow joint dislocation or fracture. Mechanisms governing successful conservative treatment methods aimed at preventing elbow PTJC and avoiding operative treatments (e.g., physical therapy) are poorly understood. Using a previously established rat model of elbow PTJC, the purpose of this study was to explore the effect of varying timing, intensity and duration of active, functional exercise on joint motion outcomes. Methods. Following a surgically-induced unilateral elbow dislocation in rats, injured limbs were immobilized in bandages for 42 days followed by free mobilization for 42 additional days producing long-term PTJC. This work summarizes several studies (Phases I-III) that investigated the effects of early versus delayed therapy (timing), free mobilization versus forced treadmill walking (intensity), and limited-time versus unlimited use (duration) on elbow PTJC. Results. Joint motion outcomes in therapy groups showed no improvements compared to non-treated injured animals when therapy began day 14 post-injury or later regardless of timing, intensity or duration. Improved joint range-of-motion was only achieved when bandages were permanently removed at day 3 post-injury, regardless of whether added treadmill walking was performed. Conclusions. Early motion is essential to preserving range-of-motion following traumatic elbow injury in a rat model.

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