A 64-year-old man comes to the office for evaluation of leg pain. The patient underwent a below-the-knee amputation 3 months ago due to a nonhealing plantar ulcer associated with osteomyelitis. He has been trying to be fitted for a walking prosthesis but bearing weight on the stump has caused significant pain. The patient describes the pain as an intermittent burning sensation that has not improved with pain medication. Medical history is notable for type 2 diabetes mellitus, hypertension, and peripheral vascular disease. The patient smokes a pack of cigarettes a day and has 1-2 drinks every night. On physical examination, the amputation incision is well healed, and the distal flap has no areas of blanching. There is slight bogginess over the end of the skin flap. Gentle pressure over the flap reproduces the pain, which radiates up the leg. Which of the following is the most likely cause of this patient's leg pain?

Question

A 64-year-old man comes to the office for evaluation of leg pain.  The patient underwent a below-the-knee amputation 3 months ago due to a nonhealing plantar ulcer associated with osteomyelitis.  He has been trying to be fitted for a walking prosthesis but bearing weight on the stump has caused significant pain.  The patient describes the pain as an intermittent burning sensation that has not improved with pain medication.  Medical history is notable for type 2 diabetes mellitus, hypertension, and peripheral vascular disease.  The patient smokes a pack of cigarettes a day and has 1-2 drinks every night.  On physical examination, the amputation incision is well healed, and the distal flap has no areas of blanching.  There is slight bogginess over the end of the skin flap.  Gentle pressure over the flap reproduces the pain, which radiates up the leg.  Which of the following is the most likely cause of this patient's leg pain?

Quizplus · Accepted Answer

11ec25c8_d962_5640_bc81_1da8f1600da1_MD0003_00 This patient has intermittent stump pain despite good wound healing following lower extremity amputation. The pain is elicited by focal palpation near the operative site, which suggests a post-traumatic neuroma. Post-traumatic neuromas are initiated by the transection of nerve fibers, which leads to an inflammatory reaction and formation of a tangled mass of unmyelinated nerve endings. These nerve endings have decreased depolarization thresholds that cause pain signals spontaneously or in response to nonpainful stimuli. Post-traumatic neuromas form over several weeks to months following injury or amputation. Because the pain is worsened by local pressure, neuromas can complicate fittings for prosthetic devices. The diagnosis is based primarily on clinical grounds, but injection of a local anesthetic can provide transient pain relief and confirm the diagnosis. Management typically involves excision of the neuroma; tricyclic antidepressants and antiepileptic medications can be used for pain management prior to surgical intervention. (Choice A) Heterotopic ossification is characterized by abnormal soft tissue calcification. It is more common in traumatic amputation, in which the amputation line passes through a region of damaged tissue, than in surgical amputation. Common associated findings include swelling, erythema, fever, and skin ulceration. (Choice C) Chronic osteomyelitis is a common complication of amputation, especially in patients with comorbid diabetes. It is typically associated with swelling, chronic wounds, or formation of weeping sinus tracts. However, minor bogginess at the amputation site is normal, and this patient has no other signs of osteomyelitis. (Choice D) Phantom limb pain is common following amputation and has a highly variable presentation. However, it is typically apparent in the first week following amputation, causes sensations felt in the distal amputated limb, and is less likely than neuroma to be elicited by point palpation. (Choice E) Stump hematoma typically presents with swelling, ecchymosis, and skin breakdown in the first several days following amputation. Formation of a chronic, expanding hematoma may occur but is rare and would not cause point tenderness with only minor soft tissue swelling. Educational objective: Post-traumatic neuromas are due to the transection of nerve fibers and form over several weeks to months following injury or amputation. They cause pain with local pressure that can complicate fittings for amputational prosthetics. Injection of a local anesthetic can provide transient pain relief and confirm the diagnosis. Management typically involves excision of the neuroma. References: Mechanisms and treatment of painful neuromas. (http://www.ncbi.nlm.nih.gov/pubmed/29306933)

A 64-Year-Old Man Comes to the Office for Evaluation of Leg