Current Concepts In Surgical Offloading Of DFUs

When one ensures proper patient selection, surgical offloading may offer key benefits for patients with diabetic foot ulcerations. Accordingly, these authors offer insights and review study findings on the use of flexor tenotomies, metatarsal head resection, Achilles tendon lengthening and external fixation to help facilitate optimal outcomes.

   For decades, the treatment of diabetic foot ulcerations has presented a major challenge for patients and podiatric surgeons alike. Traditionally, much of the treatment of diabetic foot ulcerations has centered on conservative therapy with the primary treatment focusing on eliminating abnormal pressure on the foot.

   However, patients with diabetes typically possess many more comorbidities than the average patient. These comorbidities may include abnormal biomechanics, vascular/arterial compromise, diminished protective sensation, renal disease and altered nutritional status. These factors not only put the patient with diabetes at risk for the development of ulcerations but also delay the effectiveness, and often cause conservative treatments to fail.

   In 2007, the Centers for Disease Control and Prevention (CDC) estimated that 7.8 percent of the U.S. population (or approximately 23.6 million Americans) have diabetes with the disease population growing at alarming rates.1 In 2007, the CDC also reported 1.6 million new cases of diabetes in individuals 20 years old or older.1

   Among this population, researchers have estimated that the lifetime incidence of developing foot ulcerations is as high as 15 percent.2 Despite the numerous treatments available, these ulcerations commonly become chronic wounds. These chronic wounds present a huge burden to patients with diabetes as well as to the healthcare system with costs estimated at nearly $13,200 per ulcer-related episode.3

   Some conventional modalities that physicians utilize in the treatment of diabetic foot ulcerations include padding, sharp debridement of calluses and ulcerations, orthotics, diabetic shoes, enzymatic debriders and bioengineered skin substitutes. While all of these treatments have been effective in some individuals, the “gold standard” for reducing abnormal pressure in diabetic foot ulcers, especially plantar ulcers, is a total contact cast (TCC).

   Total contact casts accomplish offloading by evenly distributing pressure across the plantar aspect of the foot. This modality therefore eliminates excessive pressure at one specific point and redistributes some of the forefoot pressure to the rear foot. Alternatives to the TCC include a removable cast boot. However, the TCC is often more effective since patient compliance is not usually an issue.

   Although total contact casts and these other non-surgical approaches can be effective, the surgical approach provides a more definitive result and tends to be more cost-effective.4 Even though it is controversial, non-emergent surgical treatment of diabetic foot ulcers has become an increasingly popular approach in comparison to conventional treatment.

Emphasizing Appropriate Patient Selection

   When should one consider surgery? This is often dependent upon the opinion of the surgeon but the general consensus is that one should consider surgery when flexible deformities have failed all conservative methods or when a rigid deformity exists.

   Due to the number of comorbidities that exist among the diabetic population, not all patients may be appropriate candidates for surgical intervention.

   Therefore, careful patient selection is of the utmost importance and one should assess several criteria. These criteria include but are not limited to: adequate circulation, absence of infection, general medical status, nutritional status and patient compliance. Physicians should ensure medical clearance and perform non-invasive vascular testing.

Understanding The Potential Benefits Of Surgical Offloading

   As the population of patients with diabetes continues to rise, finding a method to quickly and adequately close, and/or prevent ulcerations will be of the utmost importance. Surgical offloading may represent the new direction in the treatment of diabetic foot ulcers. It reduces the time needed to close the ulcer and possibly prevents infection, which commonly leads to amputation.

   Whether one utilizes surgical or non-surgical methods, one of the key principles in the offloading of diabetic foot ulcers is eliminating the causative pressure point leading to tissue breakdown and creating a more functional foot in the process. One can accomplish this in a number of ways including:

   • addressing any digital deformities or bony prominences;
   • performing soft tissue correction of contractures or tendon lengthenings; or
   • ensuring complete offloading via an Ilizarov external ring fixator.

   Many of these surgical offloading procedures are considered curative as they assist in healing open wounds in patients at high risk for amputation. One may also use the procedures prophylactically to reduce the risk of ulceration and/or re-ulceration in patients who are at low risk for amputation and who have not yet developed an ulceration.5

   However, using these procedures as prophylactic means of treatment in the patient with diabetes remains controversial, and these methods tend to be reserved for patients with existing ulcerations or a history of previous ulcerations.

What One Study Reveals About The Impact Of Surgery For Non-Infected DFUs

   In 1997, Piaggesi and colleagues published a groundbreaking study, which evaluated the effectiveness of surgical versus non-surgical management of diabetic ulcerations.6 The randomized trial included 42 patients with diabetic neuropathy who had non-infected and uncomplicated foot ulcerations. While one group underwent treatment with conservative methods such as non-weightbearing and regular dressing changes, the other group received resection and/or debridement of bone underlying the ulcerations.

   Results of the study showed that the surgical group had greater rates of healing, less time required to heal, fewer associated infections as well as a lower degree of discomfort and mobility restrictions.7 While this study was not a blinded study, there is at least level II evidence. The study provided some of the first evidence in favor of surgical versus conventional non-surgical management in the treatment of diabetic foot ulcers.6

Key Insights On Metatarsal Head Resection And First MPJ Arthrodesis

   In instances in which metatarsal heads are prominent or plantarflexed, resection might be indicated. A retrospective study, conducted over 11 years on 101 patients with diabetic foot ulcerations, found that metatarsal head resection was effective in healing 88 percent of the ulcerations and did so in a more timely fashion than conservative measures.7

   Our experience with metatarsal head resection has been positive. Depending on the depth of the ulcer, ancillary skin replacement with bioengineered tissue with or without negative pressure wound therapy has showed promise.

   Ulcerations at the interphalangeal joint of the hallux are other common locations. This can be due to biomechanics of the first ray, an exostosis or a sesamoid. One can utilize first metatarsophalangeal joint (MPJ) arthroplasty but be sure to emphasize careful patient selection by looking at factors such as age and desired functional status.

   In 2003, a case control study evaluated the outcomes of healing, reulceration, infection and amputation rates in patients receiving conservative versus surgical intervention.8 Researchers divided 41 patients into two groups with one group receiving a first MPJ arthroplasty and the control group receiving conservative offloading and wound care only.

   While both groups had similar rates of infection and amputation after a six-month follow-up period, the surgical group had increased rates of healing as well as less recurrence of ulcerations in comparison to the control group.

Flexor Tenotomies: Can They Be Effective For Claw Toe Deformities?

   Surgeons often use flexor tenotomies in the treatment of ulcerations in diabetic patients with claw toe deformities. Historically, physicians attempted to address such deformities with conservative measures such as supportive shoe gear and orthotics to help offload the distal aspect of the digits.

   However, offloading is often not effective when physicians use this alone. Correction of the actual deformity may be required for both healing and prevention of infection. Although flexor tenotomies do not always completely correct the claw toe deformity, tenotomies do function to offload the distal pressure enough to allow for adequate healing of ulcerations as well as to prevent ulcer recurrence.

   A 2008 study retrospectively reviewed the effectiveness of percutaneous flexor tenotomies in patients with diabetes who had claw toe deformities as well as ulcerations on the distal aspect of their digits.9 The study found after an average follow-up time of 13 months, all 14 patients with diabetes receiving percutaneous flexor tenotomy procedures were able to completely heal all 34 digital ulcerations without any significant complications.

   Even in the three cases in which osteomyelitis was present, the study authors found that with the addition of antibiotics, digital ulcerations healed with flexor tenotomies although the healing time was greater than twice as long as that for patients without osteomyelitis.9

A Closer Look At The Results Of Achilles Tendon Lengthening Procedures

   Limited dorsiflexion at the ankle joint has also been associated with the formation of forefoot ulcerations in patients with diabetes. Therefore, in order to change the biomechanical forces on the plantar aspect of the forefoot, surgeons can often perform lengthening of the Achilles tendon in patients with diabetes with existing ulcerations who are at a high risk for amputation. Surgeons commonly perform this procedure on patients who undergo a transmetatarsal amputation.

   In a 2003 randomized clinical trial involving 64 patients with diabetes, researchers studied the effectiveness of Achilles tendon lengthening on the healing rates of neuropathic plantar ulcerations.10 While both groups received a TCC, only one group underwent the Achilles tendon lengthening procedure. The study authors recorded ulceration measurements both before and after treatment in both groups, and patients presented for follow-up at seven months and for a final two-year evaluation.10

   Results after the two-year follow-up showed that 100 percent of the patients treated with Achilles tendon lengthening and TCC were able to heal their ulcerations versus 88 percent of the patients receiving TCC alone. In addition, the Achilles tendon lengthening group showed fewer recurrences of ulcerations and increased dorsiflexion of the ankle joint varying from 11.4 degrees to 15.2 degrees greater than the ankle dorsiflexion of the TCC-only group.10

   Therefore, the results of the study suggest that by increasing the amount of dorsiflexion at the ankle joint, one may be able to reduce the pressure on the forefoot significantly by means of percutaneous Achilles tendon lengthening, thus helping to heal and/or prevent plantar ulcerations in patients with diabetes.10

Pertinent Pointers On Offloading With External Fixation

   Diabetic ulcerations to the plantar heel present an even greater challenge. There are several methods podiatric physicians utilize to facilitate closure of these ulcerations. These methods include delayed primary closure, skin grafts, local flaps and free flaps.

   However, the difficulty with these procedures is finding a successful way to completely offload and prevent shearing forces to the plantar aspect of the foot. Traditional immobilization using a cast does not allow easy access to the wound for follow-up care and does not completely prevent shearing forces that disrupt the various skin closure techniques.

   On the other hand, using external fixation allows for proper immobilization and prevention of shearing forces along the plantar foot, while allowing for adequate access to the wound and proper visualization.11 The fixator is able to maintain bone and joint alignment, shorten healing time, decrease pin tract infections, and allow early weightbearing through the addition of a protective plantar plate.12 Patient compliance with offloading can sometimes be difficult due to other factors. At our institution, we have used a weightbearing external fixator with two foot plates.

   A recent study reviewed 24 patients over a six-year period to study the efficacy of using external fixation to offload and protect soft tissue on the plantar foot after surgical intervention.11 Patients were divided into two groups with one group receiving a multiplanar external fixator to allow for complete offloading and the other group receiving a monoplanar external fixator to immobilize wounds located near a joint.

   Both groups had failed several conservative methods for greater than 200 days. Both groups also underwent various modes of reconstructive efforts to address the plantar ulcerations. These reconstructive efforts included primary closure, skin grafting, local and free flaps in addition to the external fixator.

   The rate of limb salvage in the two groups ranged from 73 to 83 percent with an average time to heal ranging from 66 to 128 days after application of the external frame. The study authors concluded that the application of an external fixator with the use of a plantar foot plate provides superior offloading and prevention of shearing forces in comparison to other offloading utilities.11

   Due to the high cost and the level of expertise required to assemble ring fixators, researchers have studied a variety of other external fixation devices in the prevention of plantar pressure after wound closure.

   One such fixator is the hybrid “kickstand” external fixator, which was developed for pressure relief after soft tissue reconstruction of heel ulcerations. The benefits of this system are that it is simple to construct, durable and moderately priced in comparison to the highly expensive and difficult to construct ring fixators. This may therefore provide an alternative to casting for one who may not be as experienced with external fixation.13

In Conclusion

   Surgical offloading of diabetic foot ulcerations has proven to be an effective and inexpensive approach in comparison to non-surgical conventional methods. One can perform these procedures safely in the outpatient setting when done in a timely fashion. Surgical offloading may help in reducing both infection and amputation rates in patients with diabetes by decreasing the time required for healing.

   Regardless of the specific method, surgical intervention is not only an advantage to the patient who may have to suffer through months or years of conservative therapy, but also provides a direct benefit to the U.S. healthcare system as well by significantly decreasing the financial burden. Therefore, with the increasing costs of healthcare and the expected financial burden as the growing U.S. population ages, it seems that a shift toward early surgical intervention in appropriate patients with diabetes may be a likely means of treatment and/or prevention of diabetic foot ulcers in the near future.

Dr. Kimmel is the Residency Director of the PM&S 36 program at the Louis Stokes Cleveland Veterans Affairs Medical Center in Cleveland. He is board certified by the American Board of Podiatric Surgery.

Dr. Regler is a first-year resident at the aforementioned facility and a graduate of the Ohio College of Podiatric Medicine.

Dr. Gray is a second-year resident at the aforementioned facility and a graduate of the Ohio College of Podiatric Medicine.

For further reading, see “A Guide To Surgical Offloading In The Neuropathic Foot” in the March 2007 issue of Podiatry Today or “A Guide To Offloading The Diabetic Foot” in the September 2005 issue.

To access the archives or get information on reprints, visit www.podiatrytoday.com.

References:

1. 2007 National Diabetes Fact Sheet, Centers for Disease Control and Prevention. https://apps.nccd.cdc.gov/DDTSTRS/FactSheet.aspx 2. Gordois A, et al. The health care costs of diabetic peripheral neuropathy in the US. Diabetes Care 2003; 26(6):1790-1795. 3. Stockl K, et al. Costs of Lower-extremity ulcers among patients with diabetes. Diabetes Care 2004; 27(9):2129-2134. Caputo W. Surgical management of the diabetic foot: diabetes and lesion of the foot. WOUNDS 2008; 20(3):74-83. 5. Bevilacqua NJ, Rogers LC, Armstrong DG. Diabetic foot surgery: classifying patients to predict complications. Diabetes Metab Res Review 2008; 24(1):S81-S83. 6. Piaggesi A, et al. Conservative surgical approach versus non-surgical management for diabetic neuropathic foot ulcers: a randomized trial. Diabetic Medicine 1997; 15(5):412-417. 7. Wieman TJ, et al. Resection of the metatarsal head for diabetic foot ulcers. Am J Surg 1998; 176(5):436-441. 8. Armstrong DG, et al. Clinical efficacy of the first metatarsophalangeal joint arthroplasty as a curative procedure for hallux IPJ wounds in patients with diabetes. Diabetes Care 2003; 26(12):3284-3287. 9. Tamir E, et al. Outpatient percutaneous flexor tenotomies for management of diabetic clawtoe deformities with ulcers: a preliminary report. Can J Surg 2008; 51(1):41-44. 10. Mueller M, et al. Effect of Achilles tendon lengthening on neuropathic plantar ulcers: a randomized clinical trial. J Bone Joint Surg 2003; 85-A(8):1436-1445. 11. Clemens M, et al. External fixators as an adjunct to wound healing. Foot Ankle Clin N Amer 2008; 13(1):145-156. 12. McKee MD, Yoo D, Schemitisch EH. Health status after Illizarov reconstruction of post-traumatic lower-limb deformity. J Bone Joint Surg Br 1998; 80(2):360-4. 13. Roukis T, et al. Use of a hybrid “kickstand” external fixator for pressure relief after soft tissue reconstruction of heel defects. J Foot Ankle Surg 2003; 42(4):240-243. Additional References 14. Singh N, Armstrong DG, Lipsky BA. Preventing foot ulcers in patients with diabetes. JAMA 2005; 293(2):217-228. 15. Wu SC, et al. Foot ulcers in the diabetic patient, prevention and treatment. Vascular Health and Risk Management 2007; 3(1):65-76.