Reflex sympathetic dystrophy of the patellofemoral joint.

Eighteen patients with a diagnosis of reflex sympathetic dystrophy (RSD) affecting the knee were reviewed. Minor isolated injuries and operations about the knee triggered the original episode. The symptoms, regardless of location and mechanism of injury, occurred in the patellofemoral joint. Roentgenographic features of patchy demineralization and abnormal uptake on a 99mTc scan were typically located in the patella and corresponding femoral articular surface. At the initial stage of the syndrome, pain, hypersensitivity to touch, and inhibition of the quadriceps muscle were the most prominent features. In the later stages of the syndrome, functional instability due to quadriceps weakness created dependence on a knee brace or crutch support. Six patients whose RSD was initially misdiagnosed underwent numerous unsuccessful surgical procedures. In three of these patients, the knee was ultimately fused. All patients had an initial isolated knee injury (usually after minor trauma), and prolonged periods of immobilization and a cast, and 12 of the 18 patients were involved with workers' compensation. Early diagnosis and prompt treatment with an epidural block, followed by intensive physiotherapy, are recommended. A personal doctor/patient relationship that offers guidance and encouragement is key to successful management of this syndrome.