The "kick-off" position: A new sign for early diagnosis of complex regional pain syndrome in the leg

Background: Complex regional pain syndrome (CRPS) is a clinical entity that develops after a precipitating injury. It involves dysfunction of the sensory, autonomic, and motor systems and frequently is missed on initial presentation. The purpose of this report was to describe a simple clinical sign that can aid in its diagnosis. Methods: A retrospective review was conducted of 39 consecutive patients with CRPS type I or II seen in a foot and ankle clinic between October, 2001, and May, 2005. The diagnosis was based on clinical findings. Results: Twenty-six patients had type I (67%) and 13 patients had type II (33%) CRPS. The most common nerve involved in type II was the superficial peroneal nerve. Each patient, while sitting on the exam table, held the affected extremity with the knee extended against gravity. When the leg was pushed back to a relaxed and suspended position, the patient eventually involuntarily resumed the extended position. This position in which the patients held their legs was termed the "kick-off" position sign. Nine patients were seen at the foot and ankle clinic within 6 weeks of the initial inciting event and had an established "kick-off" position sign within 3 months from the time of injury. The disappearance of this sign correlated with the subsidence of pain. Conclusions: Patients with CRPS have variable clinical presentations. The awareness of this simple observation in the right clinical setting should raise the index of suspicion of CEPS in the differential diagnosis. Early treatment of this syndrome is associated with better outcome.