Regional variation is present in elbow capsules after injury.

Myofibroblast numbers and alpha-smooth muscle actin expression are increased in anterior joint capsules of patients with posttraumatic elbow contractures. The purpose of our study was to determine whether these changes occur regionally or throughout the entire joint capsule. We hypothesized that the alpha-smooth muscle actin mRNA expression and the myofibroblast numbers in posterior joint capsules would be elevated in elbows obtained from patients with posttraumatic joint contractures compared with joint capsules obtained from organ donor elbows without contractures. Semiquantitative reverse transcription-polymerase chain reaction was used to evaluate relative mRNA levels of alpha-smooth muscle actin. Glyceraldehyde-3-phosphate dehydrogenase was used to normalize the levels. Immunohistochemical analysis was used to determine the myofibroblast cell numbers. Higher alpha-smooth muscle actin mRNA levels were observed in elbows of patients with contractures compared with organ donor elbows without contractures. Immunohistochemical studies determined that myofibroblast numbers and the percentage of total cells that were myofibroblasts were elevated (2-2.5-fold) in the joint capsules from patients with posttraumatic joint contractures compared with similar tissue obtained from organ donor elbows without contractures. These results suggest elevated myofibroblast numbers occur throughout the whole joint capsule in posttraumatic elbow contractures, although there is some regional variation.