Team Approach: Treatment of Diabetic Foot Ulcer

At any point in time, 3% to 4% of the 29.1 million diabetic patients in the United States (9.3% of the population) will have a foot ulcer. Diabetes-associated foot ulcers and infection lead to >70,000 lower-extremity amputations yearly in the United States. Between one-third and one-half of diabetic patients undergoing a major lower-extremity amputation will die within 2 years after the amputation. Multidisciplinary population health-management strategies have been developed to decrease the rate and magnitude of this important comorbidity in the diabetic population. The goal of the present review is to provide the reader with a framework for the development of a health-care-system strategy for addressing this complex patient population.

Surgical treatment of the Charcot foot

With the increased number of diabetics worldwide and the increased incidence of morbid obesity in more prosperous cultures, there has become an increased awareness of Charcot arthropathy of the foot and ankle. Outcome studies would suggest that patients with deformity associated with Charcot Foot arthropathy have impaired health related quality of life. This awareness has led reconstructive-minded foot and ankle surgeons to develop surgical strategies to treat these acquired deformities. This article outlines the current clinical approach to this disabling medical condition.

Pin Tract Infection Following Correction of Charcot Foot With Static Circular Fixation

BACKGROUND

The traditional nonsurgical accommodative treatment for diabetes-associated Charcot foot arthropathy has been unsuccessful in improving the quality of life in affected individuals. This has led to the growing interest in surgical correction of the acquired deformity with either "super construct" internal fixation implants or fine-wire static circular external fixation. The use of static circular external fixation without implants has been demonstrated to achieve high rates of deformity correction with low complication rates. The goal of this investigation was to assess the risk of pin site infection in this high-risk patient population.

METHODS

Over an 11-year period, 283 consecutive diabetic patients underwent single-stage correction of Charcot foot deformity with static fine-wire circular external fixation and no internal fixation devices. Pin care was minimal.

RESULTS

Fifty-nine (20.8%) patients developed clinical signs of pin tract infection in at least 1 pin site. Forty-nine occurred in patients undergoing surgical correction of deformity in the foot. Eight occurred in patients undergoing surgical correction at the ankle level and 2 in patients undergoing complex reconstruction for combined foot and ankle deformity. Higher rates of pin site infections were observed in patients with osteomyelitis present at the time of surgery (25.6%) as compared with patients without evidence of infection (17.8%), although the difference was not statistically significant (P = .1184). There was no correlation between body mass index and pin site infection (P = .288). There was a statistically significant trend (P < .05) for higher rates of pin site infection in patients with elevated hemoglobin A1C levels. Erythema and drainage resolved in all patients with local pin care and empiric oral antibiotic therapy. None of the wires were removed prematurely, and all infections resolved following removal of the circular external fixator at the scheduled time for removal.

CONCLUSIONS

Pin site infection was common following surgical correction of the acquired deformity associated with Charcot foot. These acquired pin site infections were a nuisance but did not appear to add permanent morbidity or require additional surgery to resolve.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Tibial Stress Fracture Secondary to Half-Pins in Circular Ring External Fixation for Charcot Foot

BACKGROUND

There is an increasing trend for surgical correction of the deformity associated with Charcot neuroarthropathy of the foot and ankle (Charcot foot) in order to allow ambulation with commercially available therapeutic footwear. The significant rate of surgical and medical morbidity associated with extensive conventional operative correction has led many surgeons to use limited surgical dissection and stabilization with circular ring external fixation.

METHODS

A retrospective chart review was performed on 254 patients at 2 academic medical centers who underwent surgical correction for diabetes-associated Charcot foot deformity with limited soft tissue dissection and stabilization accomplished with a statically applied circular external fixator. Tibial stress fractures developed in 10 of the patients.

RESULTS

Seven of the fractures developed in the 42 patients in whom tibial block fixation was accomplished with half-pins (16.7%), and 3 fractures developed in the 202 patients in whom tibial block fixation was accomplished with tensioned fine wires (1.5%). Three of the tibial stress fractures were successfully treated with extension of the circular frame above the level of the stress fracture. Four fractures were successfully treated with closed intramedullary nailing and 3 with weight-bearing total contact casts. Two tibial fractures occurred through pin sites (all half-pins) in 120 nonneuropathic patients who underwent application of circular ring external fixators during the same 6-year period.

CONCLUSION

Tibial stress fracture is an unusual complication associated with the use of circular ring external fixation. This investigation highlights the significantly greater risk for the development of this complication in diabetic patients undergoing surgical correction for Charcot foot deformity when half-pins are used for tibial block stabilization, compared with tensioned fine wires. We now recommend the universal use of tensioned fine wires for tibial block fixation when circular ring fixation is performed in patients with Charcot foot arthropathy.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Site selection and pain outcome after autologous bone graft harvest

BACKGROUND

In foot and ankle surgery, there are multiple sites used for autologous bone graft, including the proximal (PT) or distal tibia (DT), calcaneus (C), and iliac crest (ICBG). There has been no comparison between these anatomic areas and the potential for acute or persistent pain at 1 year. The purpose of this study was to prospectively compare patient-reported outcomes of acute and persistent pain at 1 year after surgery to determine if harvest site selection made a difference.

METHODS

As part of a clinical trial examining ankle and hindfoot fusion rates with autograft compared with synthetic graft, the autologous bone graft harvest sites were assessed with visual analog pain outcome scores at 3, 24, 36, and 52 weeks after surgery. Patients with a score of 20+ defined clinically significant pain. Four harvest sites were compared: ICBG, PT, DT, and C. Fisher exact test was used to compare the graft site pain between locations.

RESULTS

Twelve percent of subjects reported clinically significant pain at 24 weeks and 8.5% at 52 weeks postoperatively. Each lower extremity harvest site (C, DT, PT) showed higher rates of clinically significant graft harvest site pain than the ICBG at 52 weeks.

CONCLUSIONS

Autologous bone graft harvest carried a risk of persistent pain at up to 1 year (weeks 24-52) in 18% of patients. Lower-extremity bone graft sites had the greatest risk for persistent pain at 1 year.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Establishing the relationship between clinical outcome and extent of osseous bridging between computed tomography assessment in isolated hindfoot and ankle fusions

BACKGROUND

Determining the success of joint fusion operations is often a diagnostic dilemma, and many factors may be considered. Most would agree that the broad categories of clinical success and radiographic success are likely most useful to determine the overall success of a joint fusion operation. Very little evidence exists to assist the surgeon in determining what constitutes a successful radiographic fusion. The aim of this study was to determine the extent of osseous bridging as measured by computed tomography (CT) that was associated with a good clinical outcome as measured by the 12-Item Short Form (SF-12), Foot Function Index (FFI), and American Orthopaedic Foot & Ankle Society (AOFAS) clinical outcomes questionnaires at 24 weeks.

METHODS

Patients who had isolated joint fusions were evaluated (n = 275) to determine the correlation of extent of osseous bridging with clinical outcome. The extent of osseous bridging across the joint in question was categorized as absent (0%-24%), minimal (25%-49%) moderate (50%-74%), or complete (75%-100%). Clinical outcome scores included the SF-12, FFI, and AOFAS outcomes score.

RESULTS

Patients evaluated to have at least minimal osseous bridging at fusion sites (25%-49%) on CT reported a clinically important improvement in SF-12, FFI, and AOFAS, whereas those with "absent" osseous bridging (0%-24%) did not report a clinically important improvement in outcome scores.

CONCLUSION

This study suggests that osseous bridging of greater than 25% to 49% at the fusion site measured by CT may be necessary to consider a hindfoot or ankle fusion clinically successful.

LEVEL OF EVIDENCE

Level IV, case series.

Survey on the need for bone graft in foot and ankle fusion surgery

BACKGROUND

Generally, autologous bone graft is felt to be an important treatment adjunct in the presence of structural deformity, surface irregularities, defects (due to trauma, surgery, or degenerative changes), or underlying comorbidities that predispose the patient to healing challenges. This study assessed the prognostic and predictive factors used in the clinical decision making for bone graft supplementation in foot and ankle fusion surgery.

METHODS

Utilizing standard survey research methodology, key-informant interviews, pretesting, and pilot testing; a survey was constructed. The survey consisted of a web-based 5-point Likert-type scale (never, seldom, sometimes, almost always, always) listing 14 clinical and 11 radiologic criteria that may influence the use of autologous bone grafting or other biologic augmentation in foot and ankle surgery. This survey was sent to Orthopaedic Foot and Ankle Surgeons in North America and Canada.

RESULTS

A total of 48 foot and ankle surgeons completed the blinded survey (73% response rate). More than 70% of responders felt bone graft was almost always (AA) or always (A) indicated in prior nonunion of the indicated joint (96%). Fewer than 50% of respondents felt poor soft tissue integrity (20%), prior foot and ankle infection (20%), and current foot and ankle infection (4%) needed bone graft. Radiologic factors marked as AA or A in over 70% of responders include radiographic evidence of nonunion (96%), avascular necrosis (87%), and others. Factors chosen as AA or A by fewer than 50% of surgeons include prior adjacent joint fusions (47%), intra-articular deformity (31%), and extra-articular deformity (13%).

CONCLUSIONS

There was some uniformity of agreement on the number of both clinical and radiologic factors that prompt a surgeon to utilize autologous bone graft to try to avoid the complication of nonunion. Surgeons may wish to consider these factors when making a decision on the use of bone graft to supplement fusion.

Inpatient management of diabetic foot disorders: a clinical guide

The implementation of an inpatient diabetic foot service should be the goal of all institutions that care for patients with diabetes. The objectives of this team are to prevent problems in patients while hospitalized, provide curative measures for patients admitted with diabetic foot disorders, and optimize the transition from inpatient to outpatient care. Essential skills that are required for an inpatient team include the ability to stage a foot wound, assess for peripheral vascular disease, neuropathy, wound infection, and the need for debridement; appropriately culture a wound and select antibiotic therapy; provide, directly or indirectly, for optimal metabolic control; and implement effective discharge planning to prevent a recurrence. Diabetic foot ulcers may be present in patients who are admitted for nonfoot problems, and these ulcers should be evaluated by the diabetic foot team during the hospitalization. Pathways should be in place for urgent or emergent treatment of diabetic foot infections and neuropathic fractures/dislocations. Surgeons involved with these patients should have knowledge and interest in limb preservation techniques. Prevention of iatrogenic foot complications, such as pressure sores of the heel, should be a priority in patients with diabetes who are admitted for any reason: all hospitalized diabetic patients require a clinical foot exam on admission to identify risk factors such as loss of sensation or ischemia. Appropriate posthospitalization monitoring to reduce the risk of reulceration and infection should be available, which should include optimal glycemic control and correction of any fluid and electrolyte disturbances.