Review Question - QID 218731

Total contact casting in isolation is associated with treatment failure of plantar diabetic foot ulcers when an Achilles tendon contracture is present. In these cases, Tendoachilles lengthening (TAL) is recommended to reduce the risk of treatment failure and/or recurrence.

Diabetic foot ulcers are very common in diabetics with peripheral neuropathy and account for up to 85% of lower extremity amputations. Early treatment and prevention are crucial to prevent the progression to gangrene. The first line of treatment involves local wound care and dressing maintenance, with the goal of providing a clean, moist environment for healing while absorbing exudate and providing a barrier to deep infection. The gold standard for mechanical relief in terms of off-loading plantar ulcerations is the total contact cast when they are clean and not actively infected, given that they are typically worn for 3-4 weeks at a time and prevent daily wound care. Unfortunately, when co-existing Achilles tendon or gastrocnemius contractures exist, a disproportionate amount of pressure is placed on the plantar forefoot in the neuropathic patient, which typically leads to ulcer recurrence within 3-4 weeks of cast removal if concurrent tendon Achilles lengthening and/or gastrocnemius recession is not performed.

Mueller et al. published a randomized clinical trial on the effect of Achilles tendon lengthening on neuropathic ulcers treated with total-contact casting. The authors randomized 64 patients and followed them for seven months, measuring the outcomes of time to ulcer healing, ulcer recurrence rate, range of dorsiflexion of the ankle, peak torque (strength) of the plantar flexor muscles, and peak plantar pressures on the forefoot. They found that all ulcers healed in the Achilles tendon lengthening group and the risk for ulcer recurrence was 75% less at seven months and 52% less at two years than that in the total-contact cast group, leading them to conclude that Achilles tendon lengthening should be considered an effective strategy to reduce recurrence of neuropathic ulceration of the plantar aspect of the forefoot in patients with diabetes mellitus and limited ankle dorsiflexion (≤5°).

Colen et al. reviewed Achilles tendon lengthening in the management of diabetic feet. The authors retrospectively compared the rates of recurrent ulceration between two patient groups who had undergone soft-tissue repair of diabetic forefoot or midfoot wounds either with or without concomitant Achilles tendon–lengthening surgery. They found that 25% of patients in the non-lengthening group and 2% of patients in the lengthened group developed recurrent ulceration requiring reoperation, which resulted in a 94% relative risk reduction for ulceration recurrence. The authors, thus, concluded that if one avoids excessive Achilles lengthening, the addition of an Achilles tendon–lengthening procedure can significantly reduce the risk of recurrent diabetic foot ulceration.

Searle et al. published a randomized controlled trial involving static calf muscle stretching in patients with diabetes and equinus contractures (≤5° dorsiflexion). They found no statistically significant or clinically meaningful effect of static calf muscle stretching on ankle range of motion, or plantar pressures, in people with diabetes and ankle equinus, leading them to conclude that static stretching without heel cord lengthening, though widely used in physical therapy, is ineffective when used as a stand-alone modality to increase ankle joint range of motion in this population.

Figure A is a clinical photograph of a chronically infected plantar foot ulceration with active purulence that has progressed to involve gangrenous transformation of the third toe.

Incorrect Answers:
Answer 2: Flexor digitorum longus tenotomy/release is effective for ulcers on the tip of toes that dynamically claw during gait, but would not have likely helped prevent this plantar forefoot ulceration from progressing to the state shown in Figure A.
Answer 3: An isolated gastrocnemius recession would not address the tight heel cord, given that knee flexion does not improve the patient's ability to dorsiflex, as noted on the patient's Silverskiold test.
Answer 4: A Keller resection arthroplasty has been described for recalcitrant plantar ulcerations of the Hallux, which this patient does not have.
Answer 5: Though pneumatic walking shoes can be used in lieu of contact casting, there is no evidence to suggest this method to be superior in terms of recurrence, and in fact may reduce compliance with off-loading given that the pneumatic walker is removable.