What is the cause of leg pain to the knee following toe amputation in a patient with diabetes (Diabetes Mellitus)?

From the Guidelines

Pain in the leg extending to the knee after toe amputation in a diabetic patient should be managed with a multi-faceted approach, prioritizing wound care, blood glucose control, and pain management with medications such as gabapentin or pregabalin, as recommended by recent guidelines 1.

Key Considerations

• The patient's risk factors for foot ulcers, including peripheral neuropathy, foot deformity, and history of foot ulceration or amputation, should be assessed and addressed according to the International Working Group on the Diabetic Foot (IWGDF) guidelines 1.
• Proper wound care is essential to prevent infection, including keeping the surgical site clean and dry, changing dressings as directed, and monitoring for signs of infection such as increased redness, warmth, swelling, or drainage.
• Blood glucose control is crucial as high blood sugar can worsen neuropathy and delay healing.
• Pain management should include medications such as gabapentin (300mg daily, gradually increasing to 300mg three times daily as tolerated) or pregabalin (75mg twice daily, increasing to 150mg twice daily if needed) to address neuropathic pain.
• Physical therapy focusing on gentle exercises and proper gait training with appropriate assistive devices can help prevent complications from altered walking patterns.

Additional Recommendations

• The patient should be educated on proper foot care, including daily foot inspections, proper footwear, and avoidance of walking barefoot or in thin-soled slippers 1.
• The patient's vascular supply should be assessed, and revascularization considered if necessary, as peripheral artery disease (PAD) is a common comorbidity in diabetic patients with foot ulcers 1.
• The patient's mental health and emotional well-being should be supported, as the experience of amputation and chronic pain can have a significant impact on quality of life.

From the Research

Pain in Leg to Knee Post Toe Amputation in Diabetic Patient

• The risk of nonhealing or infection of a wound and the need for revision are increased in diabetes-related amputations 2.
• Diabetic patients are frail, with an increased postoperative morbidity and mortality after major amputation, and factors detrimental to functional outcome include advanced age, end-stage renal disease, dementia, and above-knee amputation 2.
• Peripheral artery disease (PAD) is a significant risk factor for amputation in patients with diabetes mellitus, and patients with PAD have more than four-fold higher risk of lower limb amputation 3.
• The risk of amputation in patients treated with sodium-glucose cotransporter type-2 inhibitors and incretins is not higher compared with other anti-diabetic drugs, but pre-existing PAD is the greatest driver of amputation risk 3.
• Genetic variation in neuronal nitric oxide synthase associated protein (NOS1AP) is associated with lower extremity amputation and diabetic peripheral neuropathy in patients with diabetes mellitus 4.

Management of Pain

• First-line drug therapy for painful diabetic peripheral neuropathy includes duloxetine, gabapentin, amitriptyline, and pregabalin, but these medications do not restore sensation to affected extremities 5.
• Second-line drug therapy includes nortriptyline, imipramine, venlafaxine, carbamazepine, oxcarbazepine, topical lidocaine, and topical capsaicin, and periodic, objective monitoring of medication response is critical 5.
• Nondrug therapies with low- to moderate-quality evidence include exercise and neuromodulation with spinal cord stimulation or transcutaneous electrical nerve stimulation, and peripheral transcutaneous electrical nerve stimulation is well tolerated and inexpensive, but benefits are modest 5.

Epidemiology and Risk

• Diabetes mellitus is known to increase the incidence of PAD, accelerate disease progression, and increase disease severity, and patients with concomitant diabetes mellitus and PAD are at high risk for major complications, such as amputation 6.
• Despite a decrease in the overall number of amputations performed annually in the United States, amputation rates among those with both diabetes mellitus and PAD have remained stable or even increased in high-risk subgroups, including residents of rural areas, African-American and Native American patients, and those of low socioeconomic status 6.