Surgical Insights On Neuropathic Ulcers

Author(s): 
Clinical Editor: Lawrence Karlock, DPM

Neuropathic ulcers can be extremely problematic for diabetes patients and podiatrists alike. Exploring the ins and outs of surgical treatment, our expert panelists take a closer look at specific ulcers, helpful techniques, the merits of preoperative vascular testing and postoperative protocols.

Q: Do you perform prophylactic diabetic foot surgery? If yes, what are the common types of situations in which you would use this treatment option?
A:
All of the panelists consider prophylactic surgery in diabetes patients when conservative treatment options have failed to resolve an ulcer. John Steinberg, DPM, says these patients generally have a more rigid deformity that you can no longer sufficiently offload with corrective shoes or other devices.

Alan Catanzariti, DPM, also considers prophylactic surgery to treat a deformity with a significant sensory deficit in order to prevent ulceration. Dr. Steinberg concurs, emphasizing that ideally you want to perform this procedure prior to the patient ever ulcerating or requiring an amputation. After all, patients with a prior history of ulceration or amputation generally have higher rates of dehiscence and infection after prophylactic surgery than those who do not have that history, according to Dr. Steinberg.

Q: How do you surgically approach the plantar first metatarsal head neuropathic ulcer?
A:
Dr. Catanzariti says your approach depends upon the structural deformity causing the ulcer or the foot type. All the panelists agree you should perform a sesamoidectomy if that’s the cause of the ulcer. When he’s dealing with more rigid foot types, Dr. Steinberg says he also considers a dorsiflexory osteotomy with fixation. Lawrence Karlock, DPM, prefers to concentrate on the metatarsal itself, employing a dorsiflexory wedge at the first metatarsal base with large bone staple fixation and/or screw fixation. Dr. Karlock adds that if there’s also an equinus deformity, he will address this at the same time.
If the patient has a pes cavus foot type and a plantarflexed first metatarsal, Dr. Catanzariti says he may consider a dorsal approach to performing a metatarsal osteotomy. If the deformity is somewhat flexible, Dr. Steinberg notes he’ll generally perform a Jones tenosuspension with hallux interphalangeal joint fusion and percutaneous tendo Achilles lengthening. Dr. Catanzariti adds he will sometimes perform primary closure of these wounds.

Q: Do you use tourniquets in diabetic patients who have palpable foot pulses?
A:
While Dr. Catanzariti doesn’t use tourniquets for diabetes patients, he says it’s OK to use tourniquets for patients who have normal lower arterial perfusion. Dr. Karlock says he has no problem doing this for those who have a palpable pulse. If you adhere to accepted guidelines, Dr. Steinberg says using a tourniquet can enhance your surgical view and help facilitate better outcomes.
He says it is sometimes necessary to use a thigh tourniquet when patients have arterial calcification at the ankle. However, Dr. Steinberg cautions he would never use a tourniquet when the patient has a history of peripheral arterial bypass or other contraindications. Dr. Karlock adds diabetic patients can be treated with elective surgery just the same as non-diabetic patients “as long as their diabetic glycemic control is within the normal range” and they don’t have vascular disease.

Q: What is the role of pre-op noninvasive vascular tests in your practice? Which ones do you use and why?
A:
Drs. Catanzariti and Steinberg routinely perform preoperative non-invasive vascular testing for diabetes patients who are undergoing elective foot surgery. Dr. Catanzariti says he typically orders pulse volume recordings, toe pressures and transcutaneous oximetry. In addition, Dr. Steinberg says he’ll get Doppler waveforms, segmental pressures, TBI and ABI. He emphasizes paying more attention to the TBI over the ABI given the medial arterial calcification that commonly occurs at the ankle, which can cause false elevation of the ABI measurement.
When Dr. Karlock is treating a patient with diabetes who has palpable dorsalis pedis and posterior tibial pulses, he feels that he doesn’t have to do any vascular testing in this situation. However, if he is unsure of vascular flow to the foot, he will order testing with an accredited vascular lab at the local hospital.
In these scenarios, Dr. Karlock says he is primarily looking for an absolute toe pressure number. He relies upon toe pressures above 55mmHg, noting that patients with this number have had uneventful healing in up to 97 percent of diabetic foot surgery cases.
If Dr. Karlock is still unsure after vascular testing, he will refer the patient to an accredited, board-certified vascular surgeon for preoperative vascular clearance.

Q: Are there any different postoperative protocols you follow with these patients?
A:
Emphasizing that he is “extra cautious” in the postoperative period, Dr. Karlock says he limits weightbearing in these patients as much as possible and gives them oral antibiotics. Dr. Karlock notes that the rate of soft tissue infection when operating in the face of an open ulceration ranges between 15 and 20 percent, according to most of the literature on the subject. He says he usually places these patients on an antibiotic that covers gram-positive organisms. Dr. Steinberg says he generally emphasizes cephalexin 500mg qid for seven to 10 days and observes the wounds more closely.

While Dr. Catanzariti feels the postoperative course for diabetic patients is essentially the same as for non-diabetic patients, he says there are several things he does differently. When these patients need a cast, Dr. Catanzariti notes he will typically use a total contact cast or a cast that specifically offloads any areas of osseous prominence.
Given that a patient’s lack of protective sensation may predispose him or her to iatrogenic ulceration with any cast, Dr. Catanzariti emphasizes that he’ll often have diabetic patients return to his office more frequently and at shorter intervals. He says the more frequent office visits allows him to ensure there are no iatrogenic ulcers or impending infection from the cast. Even when he doesn’t apply a cast, Dr. Catanzariti recommends more frequent dressing changes given the higher risk of infection.
Dr. Steinberg adds that employing unna boots or other compression systems can be helpful in controlling the common postoperative edema in these patients and preventing dehiscence of the incision site.
Dr. Catanzariti also considers taking serial radiographs more frequently for diabetic patients after elective foot surgery to evaluate for any impending Charcot process. He notes a relatively high incidence of acute Charcot changes following elective foot surgery or trauma in the diabetic foot. Accordingly, Dr. Catanzariti has a higher index of suspicion with these patients and makes a point of educating them about possible Charcot changes.

Q: How often do you address an equinus deformity in diabetics with plantar ulcerations? What procedure do you prefer?
A:
When Dr. Catanzariti sees equinus deformity in these situations and believes it is a contributing factor, he says he’ll consider performing an Achilles tendon lengthening as an ancillary procedure to the primary elective procedure whether it’s in the forefoot or hindfoot. Dr. Catanzariti says his typical approach is a three-incisional hemisection Achilles tendon lengthening.

Dr. Steinberg, who sees this deformity “very often” in these patients, generally uses the same approach as Dr. Catanzariti. Dr. Steinberg adds that the “simple procedure” can be performed outpatient with a local block of lido with epi to the incision sites along the posterior leg. Specifically, he says he performs the distal site medially, the central site laterally and the proximal site medially, and closes each with single prolene suture.
Dr. Karlock also opts for the Achilles tendon lengthening procedure to address an equinus deformity. He prefers the open technique unless there is an isolated gastrocnemius equinus. In those cases, Dr. Karlock will perform a strayer-type gastrocnemius recession.
He says this is an important deformity to address surgically for even forefoot ulceration, as it basically “makes these patients less propulsive and decreases the forefoot pressure and sheer forces.” For patients who have a transmetatarsal amputation or a Chopart’s amputation with recurrent plantar ulceration, Dr. Karlock says he will perform an Achilles tenectomy through a small incision and make a through and through cut through the Achilles tendon.

Dr. Catanzariti is the Director of Residency Training within the Division of Foot and Ankle Surgery at the Western Pennsylvania Hospital in Pittsburgh, Pa. He is a Fellow of the American College of Foot and Ankle Surgeons.
Dr. Steinberg is an Assistant Professor in the Department of Orthopaedics/Podiatry Service at the University of Texas Health Science Center in San Antonio. He is a Fellow of the American College of Foot and Ankle Surgeons.

Dr. Karlock (pictured at the right) is a Fellow of the American College of Foot and Ankle Surgeons and practices in Austintown, Ohio. He is a member of the Editorial Advisory Board for WOUNDS, A Compendium of Clinical Research and Practice.

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