Rare case of autonomic instability of the lower limb presenting as painless Complex Regional Pain Syndrome type I following hip surgery: two case reports

INTRODUCTION: According to the International Association for the Study of Pain criteria of 1994, pain is a diagnostic requirement for Complex Regional Pain Syndrome type I. However, other authors have suggested that patients can rarely present with the sensory and vascular symptoms of Complex Regional Pain Syndrome without pain. This entity has not been reported following hip surgery in the English medical literature. CASE PRESENTATION: We present two cases of Complex Regional Pain Syndrome-like symptoms following hip surgery and with the total absence of pain. The first case was a 29-year-old Caucasian woman who had a reattachment of the greater trochanter following non-union of an intertrochanteric osteotomy of the hip. Five weeks later, the patient presented with features of Complex Regional Pain Syndrome but with the absence of pain. The second patient was a 20-year-old Caucasian woman who had undergone an open debridement and repair of a torn acetabular labrum. Ten days later, the patient presented with features suggestive of Complex Regional Pain Syndrome which was again painless. Both patients were non-weight bearing at presentation and the symptoms resolved following recommencement of weight bearing. CONCLUSIONS: The authors believe these symptoms are manifestations of vascular changes to the lower limb as a result of non-weight bearing status. Painless Complex Regional Pain Syndrome-like symptoms may occur in patients who are kept non-weight bearing following hip surgery. However, vascular insufficiency and deep venous thrombosis must be excluded before this diagnosis is made. If the clinical situation permits, early weight bearing may relieve symptoms. Orthopaedic and vascular surgeons should be aware of this entity when a postoperative patient presents to them with the above clinical picture. This is also relevant to general practitioners who are likely to see the patients in the postoperative period.