Approximately 3 percent of the United States population has diagnosed diabetes mellitus.1 Diabetic foot problems, however, are the leading cause of amputation.2,3 The risk of amputation is 15 times greater in patients with diabetes than in other people.2 Up to 15 percent of patients with diabetes will require amputation.1,3 Over 50,000 amputations in patients with diabetes occur annually in the U.S.4 In one study of patients with diabetes mellitus, 84 percent of lower extremity amputations were preceded by foot ulcers.2
Among people with diabetes, about 15 percent will eventually have foot ulcers.1,5 In the absence of large vessel disease, diabetic forefoot ulcers result from the combination of neuropathy and abnormal mechanical stress.1,6,7 Deformity that increases stress on a portion of the foot can instigate ulceration in a patient with diabetic neuropathy.1,6,7 Peripheral neuropathy results in the loss of protective sensation and a lack of recognition of repetitive mechanical stress, which often cause forefoot ulcers in patients with diabetes.1,7
Diabetic motor neuropathy and glycosylation of collagen may contribute to calf tightness and decreased dorsiflexion of the ankle, which increase pressure on the forefoot.7,8 The high forefoot pressure is consistent with the most common locations (the plantar surface of the metatarsal heads and the hallux) of foot ulcers.7,8
Patients who have experienced previous foot ulceration have abnormally high pressures at healed ulcer sites.9 Plantar foot ulcers occur at sites of high pressure.7,10 The combination of neuropathy and decreased ankle dorsiflexion has been implicated in the cause of forefoot ulcers.7,11,12 One should reduce the risk of neuropathic ulceration of the forefoot by decreasing pressure on the forefoot.9 One may accomplish pressure relief via shoe modification, total contact casts (TCCs) and tendo-Achilles lengthening (TAL).13,14
Total contact casting is an effective technique for healing diabetic neuropathic foot ulcerations.5,15,16 However, separate studies have shown that between 20 percent (20 of 102) to 81 percent (21 of 26) of the ulcers healed by TCC have recurred in two years.15,16 Dorsiflexion of the metatarsal osteotomy also is effective in healing chronic neuropathic forefoot ulcers but has a much higher complication rate.17
Tendo-Achilles lengthening promotes healing of chronic foot ulcers in patients with neuropathy (see photos on page 26 and page 29).12,18,19 When researchers employed TAL, they found that healing occurred in patients who did not heal by TCC and there were fewer ulcer recurrences in patients who underwent TAL as compared to patients who had ulcers healed with TCC.18
Assessing The Impact Of TL Procedures On Plantar Forefoot Ulcers
We performed a study to assess the impact of tendon lengthening (TL) in treating patients with plantar forefoot ulcers. Between May of 1995 and October of 2002, we offered TL procedures to all patients who presented with plantar forefoot ulcers without active infection or gangrene. Twenty-four patients with one or more plantar forefoot ulcers agreed to undergo the TL procedure.
When it came to metatarsal head ulcers, we performed lengthening of the gastrocnemius-soleus mechanism. Using the Vulpius technique, we transected the proximal tendon of the gastrocnemius muscle and underlying aponeurosis of the soleus muscle in the mid-calf.20 Peroneus longus (z-type) lengthening for first metatarsal ulcers and posterior tibial (intramuscular) lengthening for fifth metatarsal and cuboid ulcers improved varus-valgus alignment. We proceeded to place the patient’s ankle in a neutral position in a short leg walking cast for six weeks bearing full weight. The Vulpius procedure lengthens the gastrocnemius tendon and soleus aponeurosis proximal to the actual Achilles tendon. Both the Vulpius procedure and Achilles TL increase ankle dorsiflexion in a similar manner.
For toe ulcers, the physicians in the study performed a toe flexor tendon tenotomy percutaneously at the proximal phalanx. Patients usually underwent toe tenotomy in the office whereas patients usually underwent the calf surgery on an outpatient basis. Due to a higher recurrence rate of first toe ulcers, physicians recommended both calf and toe procedures to patients with first toe ulcers. Patients bore full weight on the operated side and left the hospital the day of surgery unless they were in the hospital for another reason.
The physicians involved in the study measured the amount of active ankle dorsiflexion with the knee in full extension preoperatively with a goniometer. They measured pulses via palpation of the dorsalis pedis and posterior tibial arteries. All patients without pulses received referrals for evaluation and treatment by a vascular surgeon but none of these patients were considered candidates for vascular surgery.
Using the Wagner classification, physicians graded ulcers as follows:
Grade 1: superficial;
Grade 2: deep, extending to ligament, tendon, joint capsule, fascia or bone;
Grade 3: Grade 2 with infection (abscess, osteitis or osteomyelitis);
Grade 4: gangrene of the toe or forefoot; and
Grade 5: gangrene of the entire foot.
Grade 3 to 5 ulcers were not included in the study unless the physicians could convert Grade 3 ulcers to Grade 1 or 2 ulcers with antibiotics.21 Some patients with prior ulcers and infections had been treated in the past by other physicians with amputation of toes and/or metatarsal heads but were not excluded from this study. If patients were unable to feel the 5.07 nylon monofilament in multiple areas without callus or ulcer on the plantar foot, researchers considered these patients neuropathic.22
Employing the monofilament test, the researchers noted that all 24 patients who agreed to undergo the TL procedure had neuropathy. Twenty had diabetes mellitus, two had lumbar radiculopathy, one had hemiplegia and one had alcoholism. The patients’ ages ranged from 33 to 81 at the time of surgery with an average age of 60. There were 11 males and 13 females.
Researchers treated 34 ulcers, which included 17 metatarsal ulcers (14 metatarsal head ulcers), 11 first toe ulcers, five lesser toe ulcers and one cuboid ulcer. All patients had calf tightness with inability to dorsiflex the ankle beyond 10 degrees with the knee extended and the average active dorsiflexion was -6 degrees for the 34 ulcers.
Twenty ulcers were Grade 1 and 14 were Grade 2. Thirteen ulcers had associated cellulitis that was treated with antibiotics prior to surgery. Once the infection appeared to be under control, patients underwent TL. Five patients had one or more toes previously removed and three had one or more metatarsal heads removed. The ulcer duration prior to surgery ranged from one month to seven years (an average of 10 months in ulcer duration). Most patients had unsuccessful attempts to heal the ulcers with decreased weightbearing, debridement and shoe modification.
Strong Results, Little Recurrence
Out of the 34 ulcers that were treated with TL procedures, 33 healed. All incisions healed primarily without any infections. Thirty-two of these ulcers healed within two months while the cuboid ulcer healed in five months. Pulses were not palpable in seven patients. One patient had no pulse, was on dialysis and the ulcer did not heal. He later developed gangrene of the foot and required a transfemoral amputation.
There were four ulcer recurrences among the 33 healed ulcers. One patient with a recurrent toe ulcer agreed to undergo a toe TL and the ulcer healed. A transfer ulcer on the heel of another patient occurred when the patient got the cast wet and broke the heel of the cast and failed to return to the office immediately. This ulcer also healed. Two other patients had transfer ulcers in toes. Both healed after a toe tenotomy.
No new deformities developed and no patient had development or progression of Charcot arthritis after the TL procedures. The follow-up ranged from 12 months to 81 months with the average follow-up being 36 months for the 34 ulcers. There were three complications in addition to the aforementioned ulcer recurrences. One patient had a pulmonary embolus more than three months after the first surgery but recovered completely. Another patient developed gangrene without a foot ulcer 12 months after surgery and had a transtibial amputation. Another patient had a traumatic open dislocation of her fifth toe and underwent a subsequent amputation.
What The Literature Comparison Reveals On Recurrence Rates And Complications
Ulcer recurrence rates for all groups in this study were much lower than the previously reported recurrence rates in patients with no surgery and TCCs with and without subsequent Achilles lengthening.16,23
Yosipovitch and Sheskin and Lin, et. al., previously reported the association of gastrocnemius-soleus contracture, neuropathy and chronic ulceration of the forefoot in this group of patients.11,18 The high rate of successful healing of forefoot ulcers after Achilles lengthening in these studies, seven of eight (88 percent) and 14 of 15 (93 percent) respectively, was similar to the success rate in our study: 33 of 34 (97 percent).11,18
In regard to the ulcers that did recur in our study, three were on the first toes. The first toe ulcers may have recurred because the short flexors were not cut in a percutaneous tenotomy at the proximal phalanx in the first toe whereas both short and long toe flexors were cut in the other toes. Both short and long first toe flexors are now cut percutaneously with no recurrences thus far. Another patient experienced an ulcer recurrence at the third metatarsal head but this may have been partially related to a prior first ray amputation.
The reported recurrence rate of foot ulcers in patients with diabetes treated without TL after three years was 61 percent (280 of 458).23 After performing TAL, Yosipovitch and Sheskin had three ulcer recurrences in eight patients (38 percent) in a four- to five-year follow-up, and Mueller, et. al., saw recurrence in 38 percent (10 of 26) at a two-year follow-up.11,16 The low rate of ulcer recurrence, 12 percent (four of 33), in our series compares favorably to previous studies, in which patients underwent treatment without TL, with TL and in the aforementioned TCC studies, which revealed a 20 percent (20 of 102) and 81 percent (21 of 26) recurrence at a two-year average follow-up.11,15,16,23 Lin, et. al., saw no recurrences but had shorter follow-up (17 months vs. 36 months) and treated fewer ulcers (15).18
The controlled, randomized study of Mueller, et. al., showed a high rate of ulcer healing: 89 percent (29 of 33) with TCC and 100 percent (30 of 30) when they combined TCC with TAL.16
Their results are similar to our study in which 97 percent (33 of 34) healed with TL alone. This study indicates that TCC is not necessary for forefoot ulcer healing. Mueller, et. al., reported a 38 percent ulcer recurrence rate with TL (10 of 26) while our ulcer recurrence rates were 12 percent (4 of 33) in healed ulcers or 10 percent (1 of 10) of healed metatarsal head ulcers in patients with diabetes. Both of these results are much less than the reported ulcer recurrence rate – 81 percent (21 of 26) – with TCC alone.16,23
Dorsiflexion metatarsal osteotomy also had a high rate of successful healing of neuropathic forefoot ulcers of 95 percent (21 of 22).17 However, there was a 68 percent complication rate with seven patients developing acute Charcot disease, three developing midfoot ulcers, three deep wound infections, two transfer ulcers under adjacent metatarsal heads and one below-knee amputation. Our study revealed no new or worsening Charcot disease, new midfoot ulcers, transfer metatarsal ulcers or wound infections. As I noted previously, there were three transfer lesions, all of which eventually healed.
In this study, researchers considered gangrene to be a contraindication to TL. However, they considered patients without pulses potentially salvageable. There were no incision problems and ulcers healed in all but one of these patients.
In a study of diabetic amputations, 84 percent (67 of 80) were attributed to ulcers.23 Two of the 24 patients (8 percent) in our study required amputation of the leg for gangrene but none required amputation for progressive infection from an ulcer at average follow-up of 36 months. This is less than the reported total amputation rate of 22 percent (101 of 458) at three years of observation of patients with diabetes with prior foot ulcers.23 Their rate of amputation for complications of recurrent ulcers – 21 percent (98 of 458) – was much higher than our study, in which there were no amputations caused by recurrent ulcer complications. Granted, the number of patients in our study is small by comparison so another study of more patients is necessary to confirm the decrease in amputation rate when clinicians employ TL procedures.
A Closer Look At The Vulpius Technique
Lin, et. al., and Mueller, et. al., lengthened the Achilles tendon by Hoke’s method of hemisection at three levels of the tendon.16,17,24 Yosipovitch and Sheskin used the subcutaneous tenotomy method of Strohmeyer.24,25 Nishimoto, et. al., preferred gastrocnemius recession for diabetic forefoot ulceration because of the lower risk of over-lengthening, calcaneal gait and plantar heel ulceration with a 16 percent recurrence rate.26
I chose the Vulpius technique because of prior favorable experience using this technique in children with cerebral palsy. This technique allows immediate full weightbearing in a cast with less over-correction and incision problems.20 Takahashi and Shrestha successfully used the Vulpius procedure to correct equinus deformity of the ankle in 230 adults after cerebrovascular accident.27 The average age was 68 and 98 patients had diabetes. They had no wound or tendon problems and allowed standing in a brace (ankle foot orthosis) the next day.
When it comes to determining the TL technique for treating forefoot ulcers, it is up to the surgeon’s discretion. The addition of peroneus longus or posterior tibial and/or toe flexor lengthening may have been the reason for the lower ulcer recurrence rate (12 percent) in this study as compared to the 38 percent recurrence rate reported by Mueller, et. al.
The purpose of TL procedures is to decrease stress on the area of ulceration. Tenotomy of the toe flexor tendons decreases stress on the plantar surface of the toe. Peroneus longus lengthening should decrease pressure on the first metatarsal head and the posterior tibial lengthening should decrease pressure on the fifth metatarsal.
Lengthening the gastrocnemius-soleus mechanism should decrease stress on the entire plantar forefoot. Armstrong, et. al., confirmed that Achilles lengthening decreases pressure on the forefoot, recommending the procedure as an adjunctive therapeutic and prophylactic measure to reduce the risk of neuropathic ulceration.14 Performing TL prophylactically on these and other patients with prior ulcers, impending ulcers or progressive callus has shown no recurrences thus far.
Another study should determine if daily calf stretching can prevent calf tightness and progression to forefoot callus, forefoot ulceration and Charcot arthritis in patients with diabetes. Since calf stretching might help and probably would not harm patients with diabetes, it now seems reasonable to recommend prophylactic calf stretching to these patients.
The results of this series of patients suggest that lengthening of the tendon-muscle units is effective treatment for neuropathic forefoot ulcerations. Tendon lengthenings would not be expected to prevent amputation in patients with severe peripheral vascular disease and gangrene. However, by healing most forefoot ulcerations and lowering their recurrence rate, this procedure appears to lower the incidence of progression of forefoot ulceration to infection and subsequent amputation. A follow-up study to document these findings better with more patients and larger groups of different ulcer locations is underway.
Dr. Laborde is a Consulting Surgeon in the Department of Orthopedic Surgery at Touro Infirmary. He is a Clinical Assistant Professor of Orthopaedic Surgery at the Tulane University School of Medicine. Dr. Laborde is affiliated with the Louisiana State University Health Sciences Center in New Orleans, La.
Dr. Steinberg (pictured) is an Assistant Professor in the Department of Surgery at the Georgetown University School of Medicine in Washington, D.C. He is a Fellow of the American College of Foot and Ankle Surgeons.
This article was adapted with permission from the May 2005 issue of WOUNDS: A Compendium Of Clinical Research And Practice.
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