Myofibroblast Upregulators are Elevated in Joint Capsules in Posttraumatic Contractures

We hypothesized specific growth factors are increased in the elbow capsules of patients with post traumatic elbow contractures. A model of surgically induced joint contracture in rabbit knees was developed to study the growth factor expression in joint contractures. This study demonstrates this model mimics the human condition and analyzes how the growth factor levels decrease with time in rabbit knees with contractures. Reverse transcription polymerase chain reaction was used to measure mRNA levels of transforming growth factor-beta1, connective tissue growth factor, ED-A of fibronectin, and alpha-smooth muscle actin normalized to a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. In the joint capsules of patients with elbow contractures, mRNA levels were increased for transforming growth factor- beta1, connective tissue growth factor, and alpha-smooth muscle actin. In the joint capsules of rabbit knees with contractures, mRNA levels were increased for transforming growth factor- beta1, connective tissue growth factor, ED-A of fibronectin, and alpha-smooth muscle actin. The mRNA levels for transforming growth factor-beta1, connective tissue growth factor, and alpha-smooth muscle actin decreased with time in rabbit knees. The elevated levels of these myofibroblast up-regulators and fibrogenic growth factors could explain the previously reported increase in myofibroblasts and collagen mRNA levels. The rabbit knee model correlated well with the human post traumatic elbow contractures.