Up to 50% of patients who sustain an elbow injury subsequently develop some type of contracture, making elbow contracture following trauma a common and vexing clinical scenario. While we do not completely understand the molecular basis or structural mechanisms underlying these contractures, we do know that active range-of-motion (ROM) exercises and gentle stretching are often helpful, whereas prolonged immobilization and forceful passive ROM exercises are often, if not always, detrimental.
In the March 6, 2019 issue of The Journal, Dunham and colleagues document with a rat model a better understanding about which specific tissues around the elbow account for this condition. They performed a surgical procedure on rat elbows to simulate a dislocation and then immobilized the injured extremity for 6 weeks. After the authors obtained ROM measurements at that point, some of the rats were allowed an additional 3 or 6 weeks of free active motion before a postmortem surgical dissection was performed to determine which soft tissues were most responsible for the subsequent contracture.
While the authors hypothesized that all soft tissues (muscles/tendons, anterior capsule, and ligaments/cartilage) would play a significant role in posttraumatic stiffness, they found in fact that the ligaments and cartilage caused 52% of the lost motion after 21 days of free motion and 74% of the contracture after 42 days of free motion. With this information, clinical therapies such as pharmacologic infiltrations or biophysical energy delivered to the ligaments or cartilage could be investigated. In addition, refined surgical techniques focused on these structures could be proposed and analyzed. This study represents a small preclinical step in further understanding the mechanisms of joint contracture, but it provides a foundation on which further investigations can be built.
Marc Swiontkowski, MD