Incidence of life-style related diseases such as diabetes mellitus, hypertension, and hyperlipidemia has been increasing. Patients with life-style related diseases tend to have a shoulder joint contracture following joint immobilization due to fractures or inflammatory conditions. If once this joint contracture occurs, total period of treatment becomes longer and disability becomes serious. We developed a diabetes mellitus and hyperlipidemia (DM-HL) rat model to investigate the pathomechanism of joint contracture.
Materials and Methods
Streptozosin (45mg/kg) was injected. Rats were fed by 1% cholesterol addition special food. Blood sugar value, weight, total cholesterol, triglyceride were measured. After breeding for 12 weeks, a left knee joint was immobilized. Saline was continuously injected into knee joint to measure the change of internal pressure to estimate the elasticity of joint capsule. Contractile function of the gastrocnemius muscle was measured and the tissue around th
e joint was histologically examined.
Average values of blood sugar, cholesterol, and triglyceride were 495, 739 and, 185 mg/dl after breeding for 12 weeks, respectively. The significant contracture was observed four weeks after immobilization in the experimental group. Joint motion was restricted and muscle contractile function was deteriorated. The initial phase of the intra-articular pressure caused by continuous saline injection was lower in the DM-HL rat group than that in control rats. Histologically, fibrous tissue growth and muscular atrophy were recognized in gastrocnemius muscles in DM-HL rats.
We developed DM-HL rat model. Four weeks immobilization of the knee joint produced joint contracture. In the control group, restriction of joint mobility was supposed to be produced by loss of joint capsule elasticity. Whereas, in the DM-HL rat group, a restriction of joint mobility was supposed to be produced by degeneration of skeletal muscle around the joint, not by loss of joint capsule elasticity. Less