A Guide To Surgical Offloading In The Neuropathic Foot
The neuropathic foot presents unique challenges when treating and preventing chronic wounds. One of the most difficult challenges is offloading the neuropathic foot without compromising function or causing a transfer of pressure that leads to further ulceration. When performing a limb salvage procedure, the goal is to provide the patient with a stable, plantargrade foot while still allowing for ambulation.1
In choosing the appropriate procedure to offload the foot, it is important to consider minimal bone resection versus a partial pedal amputation. In addition, one should consider specific tendon balancing procedures to maintain a functional limb. Accordingly, let us take a closer look at common pedal ulcerations and their corresponding surgical management.
How To Offload Hallux And Lesser Digital Ulcerations
As hammer digit syndrome, including hallux hammertoe, is inherent to the progressively insensate foot, so are the distal clavi and tuft ulcerations. For these patients, the anatomical consideration is the combination of increased distal pressure, the rigidity of the deformity and subcutaneous fat protection of the distal phalanx. One may extrapolate the stepwise process of reduction in these deformities — which has been useful in normal hammertoe correction (as popularized by Green) — to prevention and cure in the patient with neuropathy.
Often, simple arthroplasty procedures, tenotomy and capsulotomy, or more aggressive treatment such as distal interphalangeal joint disarticulation will be definitive in solving this issue. While flexor tenotomy is one of the last considerations in the stepwise approach, one should consider it as a viable treatment option for hammer digit syndrome in the progressively insensate foot. When choosing this alternative, take care to avoid extension contractures or a lack of toe purchase.
Hallux IPJ ulcerations are also frequently present in the neuropathic foot. Neuropathy combined with limited joint mobility at the metatarsophalangeal joint (leading to increased plantar pressure) becomes the aggravating factor. Keller arthroplasty is warranted when conservative treatment fails to heal or maintain healing of ulcers of the great toe.2 One might also consider the range of options in the surgical management of hallux limitus and rigidus as other alternatives. The success of the procedure depends on increasing the range of motion of the hallux.3
A recent retrospective review reported on the healing rates of hallux ulcerations following a Keller procedure.4 In this retrospective study, researchers examined 11 patients with 13 ulcerations after a modified Keller procedure. At the six-month follow-up, all hallux ulcerations were healed. However, transfer ulcerations developed in five patients as a late complication. Other reported complications of the Keller procedure include lack of hallux purchase, dorsal toe contracture and lesser metatarsal stress fractures.5 Occasionally, an IPJ sesamoid might be the culprit for ulcer formation. Always obtain radiographic studies to determine the best course of action in surgical planning.
Keys To Addressing Plantar Ulceration At The Metatarsal Heads
Building upon the effects of digital deformities, we find ulcerations inferior to a metatarsal head to be a recurrent issue in patients with neuropathic feet. Retrograde force from contracted digits lead to prominent, plantarflexed metatarsal heads. Again, the rigidity of the bony deformity, gait abnormality and the presence of fat pad atrophy lead to ever increasing plantar pressures and eventual soft tissue breakdown. Surgical options might include: addressing the digital deformity as previously discussed in order to reduce retrograde force; soft tissue balancing; single or multiple metatarsal head resection; or an elevation osteotomy.