What A New Study Reveals About Tendon Lengthening For Diabetic Plantar Foot Ulcers

Monroe Laborde, MD

Presenting the results of a recent retrospective study and offering a review of the related literature, this author says tendon lengthening compares favorably to other modalities in terms of efficacy and reduced complications.

Foot ulcers are a common cause of infection and amputation in patients with neuropathy. Diabetes is the most common cause of neuropathy.1 The treatment of foot ulcers with tendon lengthening has good literature support.2-15 Ulcers from types of neuropathy other than diabetes seem to respond in the same way to tendon lengthening.2,12,13

   Pecoraro and colleagues reported that 84 percent (67/80) of amputations in patients with diabetes were preceded by foot ulcers.16 The prevention or cure of foot ulcers could potentially prevent most of these amputations.

   The treatment of foot ulcers from diabetes and other causes of neuropathy consists of managing infection, arterial insuffiency and high plantar pressure in the foot. Neuropathy causes decreased sensation and tendon tightness.2,4,6 Increased pressure from tendon tightness causes foot ulcers.4,5

   Tendon lengthening decreases plantar pressure in the foot.5 Various researchers have demonstrated that tendon lengthening is successful in healing and preventing recurrence of forefoot and midfoot ulcers with a low complication rate.2-15 With this in mind, let us take a closer look at a retrospective study of tendon lengthening for patients with diabetic neuropathic ulcers of the forefoot and midfoot. This study involves a larger number of patients and longer follow-up in comparison to previously reported studies.

Reviewing The Methodology And Protocol Of The Study

Between 1995 and 2006, I performed tendon lengthening for 105 consecutive patients with 130 plantar foot ulcers. The ulcers were months to years in duration with patients receiving previous non-operative treatment elsewhere. For this study, I included all plantar foot ulcers (from diabetes and other causes of neuropathy without gangrene (Wagner types I, II and III).17 The most common type of diabetic foot ulcer in this study was a Wagner type II. Most patients had a pedal pulse. I did include in the study patients who didn’t have a pedal pulse and sent them for vascular evaluation. No patients had vascular surgery either because their disease was too mild or it was not correctable.

   Patients with toe ulcers underwent a percutaneous toe flexor tenotomy at the level of the proximal phalanx. Those with ulcers plantar to metatarsal heads had a gastrocnemius-soleus recession. I cut the gastrocnemius tendon and soleus fascia transversely in the mid-calf just distal to the gastrocnemius muscle. I subsequently stretched the soleus muscle about 2 cm. in the operating room by dorsiflexing the ankle. Usually, I did not debride the ulcers and only removed bone for osteomyelitis in two patients with metatarsal head ulcers. I usually changed dry sterile dressings on a weekly basis.

   I added peroneus longus tendon lengthening for first metatarsal ulcers and posterior tibial tendon lengthening for fifth metatarsal ulcers. I cut the peroneus longus tendon in a Z fashion to lengthen it about 2 cm, and subsequently repaired it with 0 suture. The incision was vertical and 2 inches long, 2 to 4 inches proximal to the tip of the lateral mallelous. I lengthened the posterior tibial tendon about 1 cm. by cutting fascia over the muscle and everting the foot to stretch the muscle. The incision for this was vertical and 2 inches long, 4 to 6 inches proximal to the tip of the medial mallelous. I also performed a gastrocnemius recession for patients with midfoot ulcers.

   Postoperatively, I allowed patients full weightbearing in a removable cam walking boot for six weeks with a subsequent transition into diabetic shoes. Diabetic shoes are extra-depth, oxford-type shoes with custom inserts. Only patients with midfoot ulcers had a custom-molded insert inserted into the boot for six weeks prior to the diabetic shoe.

   I reviewed the charts in a retrospective fashion. If I had not seen the patients for more than two years after surgery, I asked them to return for follow-up. If they returned, I observed their gait and examined their feet for recurrent ulcers, deformity, amputation or other problems. If the patients would not return, I questioned them on the phone regarding recurrence and complications. Phone questioning included whether they had any problems after tendon surgery and ulcer healing such as ulcer recurrence, other wounds or subsequent surgery, amputation, deformity, weakness or gait problems.

A Closer Look At The Retrospective Study Results

I lost 30 patients to follow-up, leaving 100 ulcers in 75 patients. The last follow-up was for a person who had 14 toe ulcers, 15 metatarsal head ulcers and five midfoot ulcers. The last follow-up on the remaining patients was by phone. All patients had over two years follow-up unless they died or had an earlier amputation. Patients who died or had an amputation before two years of follow-up were included in the calculation of average follow-up. There were 46 toe ulcers, 44 metatarsal ulcers and 10 midfoot ulcers. Six patients had more than one type of ulcer.

   The average follow-up for 46 toe ulcers in 31 patients was 39 months. Pedal pulses were palpable in 27 patients and 26 patients had diabetes. All ulcers healed in less than two months (see Figure 1). No lesser toe ulcers recurred. Three first toe ulcers recurred but healed again after repeat tenotomy for the ulcer recurrence. Two patients had major amputations for gangrene and four patients died. These patients were included in the average follow-up.

   The average follow-up for 44 ulcers plantar to metatarsal heads in 40 patients was 38 months. Pedal pulses were palpable in 34 patients and 37 patients had diabetes. Only one of these ulcers did not heal. The ulcers that healed did so in less than two months. Seven ulcers recurred but healed again if patients had repeat tendon lengthening for ulcer recurrence. There were eight forefoot transfer ulcers, four toe ulcers and four metatarsal head ulcers, all of which healed after tendon lengthening. One patient had a major amputation for gangrene, four patients died and three patients developed heel ulcers. Two of the heel ulcers were posterior and one was a plantar heel ulcer. The superficial plantar heel ulcer healed with a few weeks of wound care.

   The average follow-up for 10 midfoot ulcers in 10 patients was 31 months. Pedal pulses were usually not palpable because of swelling from Charcot arthropathy. Nine patients had diabetes. Nine ulcers healed in less than four months and none recurred. In addition to tendon lengthening, one patient had an exostectomy and one patient had a midfoot fusion. If those two patients were excluded, seven of eight ulcers healed and none recurred. Two patients had amputation for gangrene and one died. They were included in the average follow-up.

   The overall results of this study, at an average follow-up of 38 months, revealed that a total of 98 percent (98/100) ulcers healed, 10 percent (10/98) ulcers recurred, 11 percent (11/98) transfer ulcers including 2 posterior heel ulcers, 1 percent (1/98) plantar heel ulcer, 7 percent (5/75) of the patients had amputation, and 12 percent ( 9/75) died. All amputations were for gangrene, which developed after ulcer healing because of ischemia. None of these amputations were due to infection from ulcers. Deaths were caused by medical problems but were not due to post-operative complications. There were no incision problems, no new foot wound infections, no new Charcot arthropathy and no progression of midfoot deformity after tendon lengthening.

Comparing Results And Complication Rates With Those From Other Studies

The strength of this study is the larger number of patients and longer follow-up than prior studies on tendon lengthening for foot ulcers from diabetes and other causes of neuropathy.2-15 The main weaknesses are the retrospective chart review and telephone follow-up of patients.

   An analysis of control groups of randomized studies revealed that “good” wound care healed only 31 percent (142/458) of diabetic foot ulcers in five months.18 Total contact casting (TCC) healed an average of 80 percent of diabetic foot ulcers.19 The present study results for tendon lengthening demonstrated a 98 percent healing rate (98/100). These non-operative approaches appear to heal fewer ulcers than tendon lengthening.

   A comparison of complications is challenging because of variable lengths of follow-up and variable reporting of complications in the literature. Guyton reported that 31 percent (22/70) of patients with TCC had developed new ulcers with a short term follow-up.20 Mueller reported an 81 percent (21/26) recurrence rate within two years after patients healed with TCC.7 There were no incision problems in the present study and only one recurrence with a new plantar heel ulcer and an 11 percent (11/98) recurrence rate at 38 months follow-up. The TCC seems to have more initial complications and a much higher recurrence rate than tendon lengthening. Dayer and Assal agree that tendon lengthening, rather than TCC, should become the “gold standard” treatment for plantar forefoot ulcers if additional studies have similar results.14

   In my study, the rates of plantar heel ulceration were 3 percent (1/40) for metatarsal head ulcers and 1 percent (1/75) for all ulcers. These rates are much lower than the 15 percent rates (11/75) reported by Holstein and colleagues.9 These lower rates are probably explained by the low rate of over-correction of equinus from gastocnemius-soleus recession in comparison to the triple-cut Achilles tendon lengthening.8,12

   Weiman and colleagues performed metatarsal head resection for 202 metatarsal ulcers in 98 patients with a mean 35-month follow-up. Death occurred in 28 percent (27/98) of patients and 13 percent (13/98) had major amputations. Eighty-eight percent (142/162) of the remaining ulcers healed. Wound infection occurred in 8 percent (17/202) of the ulcers. Transfer ulcers occurred in 72 percent (117/162) of ulcers in 54 percent (53/98) of patients.21 Their complication rates were higher than tendon lengthening.

   Using the same method of reporting complications in my study, I found that out of the 40 patients with 44 metatarsal ulcers, 10 percent (4/40) died and 3 percent (1/40) had a major amputation for gangrene. Accordingly, there were 35 patients remaining who had 38 months follow-up. Ninety-eight percent (43/44) of the ulcers healed. There was a 16 percent (7/43) recurrence rate but these ulcers healed again with repeat tendon lengthening. Accordingly, 94 percent (33/35) of the remaining patients’ forefeet healed at 38 months follow-up. There were no wound infections and a 5 percent (11/44) incidence of transfer ulcers in 40 patients. These forefoot transfer ulcers all healed after additional tendon lengthening.

   The metatarsal osteotomy for 22 ulcers plantar to metatarsal heads in 20 patients resulted in a 95 percent (21/22) healing rate. However, there was also a 91 percent (20/22) complication rate with 17 months average follow-up.22 Complications after metatarsal osteotomy included acute Charcot arthropathy in 32 percent (7/22) of the ulcers, transfer ulcers in 23 percent (5/22), wound infection in 32 percent (7/22), a below-knee amputation in 5 percent (1/22) and no recurrences. In the present study on tendon lengthening for the same problem, 98 percent (43/44) of ulcers healed with a 52 percent (23/44) incidence of complications at 38 months average follow-up. Complications included a 16 percent rate (7/43) of ulcer recurrence, a 28 percent (11/40) incidence of transfer ulcers and a 3 percent (1/40) incidence of a subsequent major amputation for gangrene. There were no wound infections and no new or acute Charcot arthropathy. Ten percent (4/40) of patients died.

   The recent thinking is that midfoot ulcers are caused by a combination of gastrocnemius-soleus tightness and a loss of protective sensation. Gastrocnemius-soleus tightness and protective sensation loss theoretically cause midfoot arthritis and/or arch collapse, which leads to midfoot plantar bony prominence and a subsequent midfoot ulcer.23,24 This theory is consistent with the lack of progression of Charcot deformity after tendon lengthening.

   Weiman and co-workers healed 60 percent (32/54) of midfoot ulcers with exostectomy but 39 percent (21/54) had an amputation.25 Early and Hansen healed 7 of 10 midfoot ulcers with fusion but noted complications in eight of these cases. Complications included two transfer ulcers, three "wound problems," two amputations and one death.26 The present study on 10 midfoot ulcers in 10 patients had an average follow-up of 31 months. Nine of 10 healed and none recurred. Two patients had amputation for gangrene and one patient died. Accordingly, there was a 30 percent complication rate in this study.

   The aforementioned studies described results of metatarsal head resection, metatarsal osteotomy, exostectomy and fusion. Tendon lengthening appears to heal more ulcers with less complications than these bony procedures.

   Ray amputation has a high 18 percent (16/89) rate of additional amputation in patients with diabetes and forefoot ulcers.27 Krause and colleagues used transmetatarsal amputation to treat chronic diabetic forefoot ulcers.28 Krause and colleagues used transmetatarsal amputation to treat chronic diabetic forefoot ulcers.28 In their study, wound breakdown occurred in 12 percent (8/65) of feet, transtibial amputation occurred in 26 percent (17/65). In addition, three of 60 patients were lost to follow up and 30 percent (17/57) died. In comparison to the complications with partial foot amputation, complication rates with tendon lengthening in the present study were lower. There was a 7 percent (5/75) incidence of amputation, no incision problems and 12 percent (9/75) died.

   The 7 percent (5/75) amputation rate in this study is less than the 16 percent (75/468) amputation rate that Apelqvist and co-workers reported in another study three years after ulcers healed after non-operative treatment.29 All amputations in this study were from gangrene due to arterial insufficiency. None of the amputations were due to ulcer infection. This amputation rate is much less than the 84 percent (67/80) amputation rate secondary to foot ulcers reported by Pecararo and colleagues.1 This is consistent with a reduced amputation rate after tendon lengthening.

   Tendon lengthening may also prevent the progression of Charcot arthropathy.15 Another study with more patients and longer follow-up is underway to further evaluate this possibility.

   Tendon lengthening is my first choice for the treatment of diabetic and other causes of ulcers plantar to the toe, metatarsal head and midfoot.2-15

In Conclusion

This study suggests that tendon lengthening is an effective treatment for plantar foot ulcers. The results of this study compare favorably with the published results of other operative and non-operative treatments for forefoot and midfoot ulcers. Tendon lengthening heals more ulcers with much less recurrence and less complications than the reported results of other treatments I have discussed above.

   Dr. Laborde is an Orthopaedic Surgeon at Touro Infirmary. He is a Clinical Assistant Professor of Orthopaedic Surgery at the Tulane University School of Medicine at Louisiana State University Health Sciences Center in New Orleans, La. and is director of Foot Clinic at LSUHSC.

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