Incidence of Skin Breakdown and Higher Amputation After Transmetatarsal Amputation: Implications for Rehabilitation

Transcription

1 50 Incidence of Skin Breakdown and Higher Amputation After Transmetatarsal Amputation: Implications for Rehabilitation Michael J. Mueller, PhD, PT, Brent T. Allen, MD, David R. Sinacore, PhD, PT ABSTRACT. Mueller M J, Allen BT, Sinacore DR. Incidence of Skin Breakdown and Higher Amputation After Transmetatarsal Amputation: Implications for Rehabilitation. Arch Phys Med Rehabil 1995;76:50-4. The purpose of this study of patients with transmetatarsal amputation (TMA) is to describe multiple patient characteristics, including the incidence of subsequent skin breakdown and higher amputation, that may influence rehabilitation treatment and outcomes. Data were gathered on all patients having a TMA at this facility between April 1989 and September One hundred twenty TMAs were performed on 107 patients with a mean age of 62.4 _ years. There were 55 men and 52 women. Thirteen patients (12%) had a bilateral TMA. Twentynine patients (27%) developed skin breakdown. Of these, 48% occurred within the first 3 months after surgery. Thirty patients (28%) required a higher amputation. Of these, 60% occurred in the first month after TMA. In addition, this group of patients had a high incidence of diabetes meilitus (77 %), hypertension (54 %), electrocardiogram (EKG) abnormalities (60%), congestive heart failure (22%), and prior ipsilateral vascular surgery (51%). These results indicate that patients with TMA often present with a complicated medical condition and that they are at high risk of skin breakdown or higher amputation, especially in the first 3 months after surgery. The investigators conclude that patients with TMA may benefit from a rehabilitation program emphasizing protection of the residuum during their return to functional activities. Additional research is needed to determine optimal acute and long-term rehabilitation of patients with TMA by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Transmetatarsal amputation (TMA) is a relatively common procedure. In 1991, the National Center for Disease Statistics reported there were 32,000 above-knee amputations, 22,000 below-knee amputations, and 10,000 TMAs performed in the United States. t TMA is now considered preferable to a below-knee or above-knee amputation because it allows a weight-bearing residuum 2'3 and has a lower mortality rate. 4 Despite the common occurrence of TMA, there is little research to aid clinicians involved in the rehabilitation of patients with TMA. Several authors have suggested that patients with TMA require only a shoe with a toe filler and perhaps a reinforced sole. 2'5'6 This prescription may be acceptable for patients with no other complications but does not appear adequate for patients with significant peripheral neuropathy or vascular disease. Patients with TMA and significant peripheral neuropathy or vascular disease are at high risk for skin breakdown and subsequent amputation. 7 Peripheral neuropathy can allow excessive, repeated pressures on the neuropathic foot leading to skin breakdown. 8'9 Inadequate blood flow can prevent or From the Program of Physical Therapy (Drs. Mueller, Sinacore), and the Department of Surgery (Dr. Allen), Washington University School of Medicine, St. Louis, MO. Submitted for publication April 4, Accepted in revised form August 16,!994. This research supported by the National Institutes of Health grant HD No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Michael J. Mueller, PhD, PT, Assistant Professor, Washington University School of Medicine, Campus Box 8502, 660 S. Euclid Ave, St. Louis, MO by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation /95/ /0 complicate primary healing. 7 Pecoraro and colleagues reported that a causal sequence of minor trauma, skin ulceration, and wound healing failure occurred in 72% of the 80 lower extremity amputations they studied. 7 The investigators speculate that prevention of minor trauma may help to reduce the number of amputations. Patients with significant neuropathy or vascular disease may benefit from rehabilitation and footwear that protects their residuum from the minor trauma that can begin the cascade of events leading to skin breakdown or higher amputation. A first step in prescribing appropriate rehabilitation and footwear for patients with TMA is to better understand the characteristics of the population. The purpose of this study is to describe multiple characteristics of patients with TMA, including the incidence of subsequent skin breakdown and higher amputation, that may influence rehabilitation treatment and outcomes. METHODS Data were gathered from the Vascular Registry at the Department of Surgery at our school of medicine, which is affiliated with a 1,200-bed hospital serving the St. Louis and Midwest area. Data were analyzed on all patients having a TMA over a 4.5-year time period between April 1989 and September For the purposes of this study, the following data are described: number of patients with TMA; number of TMAs performed; age; gender; mortality rates; number of patients with TMA that had subsequent foot ulcers; number of patients with TMA that required subsequent higher amputation (ie, below-knee or above-knee amputation); time after TMA to subsequent skin breakdown or higher amputation; history of diabetes mellitus (DM), hypertension, smoking, electrocardiographic (EKG) abnormalities

2 COMPLICATIONS AFTER AMPUTATION, Mueller 51 1 I = 12 o 0to3 4tG6 71o o o 18 > 18 TIME (months) from TMA to Skin Breakdown Fig 1--Frequency of skin breakdown according to time after TMA. Note that most skin breakdown occurred in the first 3 months after TMA. consistent with coronary artery disease, congestive heart failure, and prior vascular reconstructive surgery. Patients with DM were questioned regarding their current glycemic control (diet, oral agents, or insulin). Diagnoses of hypertension and congestive heart failure were documented by the primary medical physician. EKG abnormalities were defined as the presence of S-T segment wave changes, bundle branch blocks, or evidence of previous myocardial infarction, which are indicative of myocardial ischemia. The occurrence of subsequent death, ulcer, or amputation was determined during regular follow-up visits (usually every 3 months). Skin breakdown was defined as any open wound on the foot or ankle after TMA. Selection criteria for level of amputation were based on the clinical judgment of the surgeon. Factors included in the decision were level of infection and pain, and blood flow as measured by angiogram and doppler studies. RESULTS One hundred twenty TMAs were performed on 107 patients with a mean age of 62.4 _ years. Thirteen patients (12%) had a bilateral TMA. There were 55 men and 52 women with mean ages of _ 12.6 and years, respectively. During this 4.5 year follow-up period, 17 patients (16%) died. Hospital mortality rate, defined as death within 1 month of surgery, was 2.8% (3 patients). Three patients died within 1 to 2 months after surgery; 7 died more than 2 months after amputation; the time between surgery and the death of 4 patients was unknown. Twenty-nine patients (27%) developed subsequent skin breakdown on the residuum (fig 1). Of the 29, 31% developed skin breakdown in the first 2 months, and 48% occurred in the first 3 months after TMA. Thirty patients (28%) required a subsequent higher amputation on the same lower extremity as the TMA. Of these 30 patients, 25 were below-knee amputations, and 5 were above-knee amputations. Of the 30 higher amputations, 18 (59%) occurred in the first month after TMA (fig 2). Of the 30 higher amputations, 17 (57%) patients had vascular reconstructive surgery within 1 month of TMA. Of the 5 patients who required an above-knee amputation, all 5 (100%) had vascular surgery within 1 month of TMA. Briefly, 77% had diabetes mellitus, 54% had hypertension, 60% had EKG abnormalities consistent with coronary artery disease, 22% had congestive heart failure, and 56% reported a history of smoking. Fifty-five patients (51%) had some type of vascular reconstructive surgery a mean time of 129 days before TMA. DISCUSSION Twenty-seven percent of patients with TMA developed subsequent skin breakdown, and 28% required a higher amputation. Most of these complications occurred within the first 1 to 3 months after TMA. These results emphasize that the residuum is at high risk for subsequent skin breakdown or higher amputation, especially in the first 1 to 3 months after TMA (figs 1 to 2). The first 3 months is the time period when these patients are resuming their weight-bearing activities and may inadvertently injure their residuum or when the grafts from vascular surgery can fail. These findings are consistent with other reports. In their study of 64 midfoot amputations, Sage and colleagues reported early wound failure or reulceration in 42% of the cases, and 25% of cases required a higher amputation. 1 Hodge and associates report that 39 of 124 (31%) extremities required higher amputation. H In a study of 152 TMAs, Miller and associates report that 67 (44%) failed to heal or had a major amputation in 3 months) Slightly lower failure rates (17% to 19%) are provided by McKittrick and colleagues 2 and Sanders and Dunlap.12 These studies indicate that wound failure or higher amputation can occur in 17% to 44% of patients with TMA. These results highlight the fact that patients with TMA are at high risk for wound failure or additional skin breakdown. This patient population has many characteristics that may contribute to skin breakdown or higher amputation. Our data indicate that 77% of patients with TMA also had DM. These data are consistent with other reports on patients with TMA. 3'I~-~2 Patients with DM have a high incidence of foot disease. Foot disease is the most common complication of DM leading to hospitalization. ~3 Additionally, individuals with DM experience an age-adjusted rate of lower-extremity amputation about 15 times greater than individuals without DM. 14 2O i ~. ;o 8.o 6 Z 4 2 o < 1 1 to2 2to3 3to 12 > 12 TIME (months) from TMA to Higher Amputation Fig 2--Frequency of higher amputation according to time after TMA. Note that most higher amputations occurred in the first month after TMA.

3 52 COMPLICATIONS AFTER AMPUTATION, Mueller Peripheral neuropathy is a common complication of DM. Sanders and Dunlap report that 89% of the patients with TMA and DM had evidence of peripheral neuropathy.~2 Neuropathy is a significant factor leading to lower extremity amputation because it can allow unnoticed minor trauma to progress to skin breakdown, and eventually, infection. 7-9 Brand described the gradual decrease in sensation observed in patients with diabetes and noted a certain "threshold" of insensitivity that must be exceeded before patients are at risk for ulceration. 9 Independent investigations have identified the 5.07 Semmes-Weinstein monofilament as the best discriminator between neuropathic feet with ulceration and those without ulceration Sensory neuropathy reduces or eliminates protective sensation, and motor neuropathy leads to paralysis of the intrinsic foot muscles causing muscle imbalances and the typical claw foot deformity of the neuropathic foot. 8'9 These foot types typically are associated with prominent metatarsal heads that place increased pressure on the plantar forefoot, the site of most plantar ulcerations. 8'9 Infection of the forefoot ulcer can lead to TMA. 2 TMA reduces the weightbearing area of the foot and may further increase the peak plantar pressure and risk of skin breakdown on the residuum. Peripheral neuropathy also can cause instability during walking. Cavanagh and colleagues report that subjects in a group of patients with DM and peripheral neuropathy were 15 times more likely to report an injury during walking or standing than subjects in a control group of patients having DM but no peripheral neuropathy. ~8 Mueller et al found that patients with DM and peripheral neuropathy showed less ankle mobility, ankle moments, ankle power, velocity, and stride length during walking than age-matched control subjects. ~9 Patients with DM, peripheral neuropathy, and a TMA would be expected to have even more difficulty during weight-bearing activities, but there is little data to describe the functional level of this population accurately. In addition to peripheral neuropathy, lower extremity ischemia is an important factor in patients with TMA. The interplay between vascular and neuropathic problems appears to be particularly dangerous. 7 The diffuse nature of vascular disease in our patients is demonstrated not only by the high incidence of hypertension (54%), EKG abnormalities (60%), and congestive heart failure (22%), but also by the fact that 51% of the patients required vascular reconstruction before TMA to maximize the potential for healing. This high incidence of vascular insufficiency underscores the importance of arterial ischemia as an etiologic factor for skin breakdown and TMA. However, it is clear that vascular reconstruction before TMA is not always protective because 57% of the patients who required a more proximal amputation had prior vascular reconstructive surgery. Failure of a TMA to heal after vascular reconstruction may be caused by vascular graft thrombosis. 3 Finally, the intermittent claudication, commonly found in patients with arterial insufficiency, may compromise walking ability and therefore the potential for rehabilitation in this patient population. The mortality rate in this study was 2.8% for the first month and 16% over the 4.5 years reviewed. In other studies of patients with TMA, McKittrick reported a hospital mortality rate of 1%, 2 whereas Miller and associates reported an operative mortality of 5.6%. 3 The mortality rate of patients with TMA is generally lower than patients with higher amputations. 4 In an 8-year follow-up study of Native Americans with DM, Lee and colleagues report mortality rates of 39% of patients with toe or foot amputations, 44% of patients with below-knee amputation, and 67% of patients with above-knee amputations. 4 Implications for Rehabilitation In a general sense, clinicians working in rehabilitation should be cognizant of the accompanying chronic diseases that patients with TMA may have, monitor patients closely, and set goals appropriately. More research is needed to document the level of disability in this population with multiple chronic diseases and what might be accomplished to enhance their functional outcomes. Although there is considerable data on surgical management of TMA, 2'3'6'1 '11 there is little information in the rehabilitation literature to guide treatment. Perhaps skin breakdown, subsequent amputation, and injury rates could diminish with more appropriate rehabilitation techniques. Although it is true that these patients do not require as much rehabilitation or as an elaborate prosthesis as a patient with a below-knee amputation, they appear to require more than simply providing traditional footwear and a toe filler. As indicated in figures 1 and 2, the results of this study indicate that the patient with TMA is at highest risk for skin breakdown or higher amputation in the first 1 to 3 months after their surgery. The first 3 months after surgery is the time when patients are becoming ambulatory, and may inadvertently injure their foot or surgical incision site during weight-bearing activities. Because of the many medical complications of this patient population, we believe their condition and rehabilitation should not be further complicated with prolonged periods of bed rest. Therefore, the residuum should be protected adequately during the immediate postoperative period while activity increases. Perhaps the high TMA success rate (83%) reported by Sanders and Dunlap can be attributed, in part, to aggressive protection of the residuum during postoperative management. They describe using a posterior splint during the early postoperative period, and then fitting patients with a shortleg, non-weight-bearing cast for ambulation. 12 A similar approach is used to heal neuropathic ulcers with total contact casting, a treatment with established efficacy. 2 A limitation of total contact casting is that it does not allow easy wound inspection. An alternative to a cast may be some type of total contact, clamshell orthotic that protects the residuum but allows inspection of the residuum. We have used a walking brace on several patients with good results. A resting orthotic and early initiation of active dorsiflexion exercises also may help reduce the incidence of equinus deformity after TMA. An equinus deformity can contribute to skin breakdown on the distal aspect of an insensitive residuum. 2~ Additional research is needed to determine the optimal methods of protecting the residuum and preventing equinus deformity while progressing weight-bearing activities after TMA. After the primary surgical incision is healed, patients with TMA require definitive footwear. Because patients have a Arch Phys Med Rehab l Vol 76, January 1995

4 COMPLICATIONS AFTER AMPUTATION, Mueller 53 high incidence of skin breakdown and instability in walking, ~8 primary goals of footwear should be on protecting the skin and providing overall stability. Traditional footwear with a toe filler does not appear to be adequate to meet these goals for many patients. The addition of a steel shank may provide more stability compared with a regular shoe, but Millstein and colleagues reported that 90% of the patients fitted with a custom-made shoe with a steel shank, a toe filler, and molded insoles still complained of footwear problems. 22 Several authors recommend using a custom-made shortened shoe with a rigid rocker bottom (RRB) sole to help protect the insensitive residuum There is evidence to suggest a RRB can decrease peak plantar forefoot pressures in full length shoes 25'26 and in shortened feet. 27 The effect of a RRB on overall stability has not been determined, but because it further shortens the available lever arm of the foot, theory and clinical practice indicate that stability 28 and cosmesis 26 can be adversely affected. A full-length shoe with a polypropylene ankle-foot-orthosis may be required for some patients with TMA who have persistent problems with skin breakdown or falling to provide improved skin protection and postural stability. 28 We currently are conducting research to determine the benefits and limitations of these orthotic and footwear components in the treatment of patients with diabetes and TMA. Furthermore, patients with TMA may require training in alternative walking strategies to enhance stability and protect the residuum. There is some evidence to suggest that training patients to walk using a hip strategy may be beneficial. 19'29 Rather than pushing from the ankle using plantar flexor muscles, training patients to use a hip strategy emphasizes pulling the lower extremity forward using the hip flexor muscles. This gait pattern results in less ankle motion, a shorter step length, and lower peak plantar forefoot pressures compared with walking normally. 29 Further research is needed to determine whether training patients with TMA to walk using a hip strategy can reduce the incidence of skin breakdown. Meticulous care is required for both feet of patients at risk for foot problems. Patients should be educated in proper self-inspection, skin care, and footwear selection for the contralateral extremity. Detailed instructions for daily foot care and footwear prescription recommendations are reviewed elsewhere, s Recent legislation has provided Medicare coverage for therapeutic footwear including extra-depth shoes and custom-molded inserts to patients with diabetes. 3~ There is evidence to suggest that improved skin care and use of therapeutic shoes by patients with diabetes and severe foot disease can reduce the high rate of foot ulcers and lower extremity amputation in this patient population. 32 In summary, the results of this study indicate that patients with TMA are at high risk for skin breakdown (27%) or higher amputation (28%), especially in the first 3 months after surgery. In addition, this group of patients had a high incidence of DM (77%), hypertension (54%), EKG abnormalities (60%), congestive heart failure (22%), and prior vascular reconstructive surgery (51%). We conclude that patients with TMA may benefit from a rehabilitation program emphasizing protection of the residuum during their return to functional activities. Traditional footwear with a toe filler does not appear adequate in providing skin protection and overall patient stability. Additional research is needed to determine optimal acute and long-term rehabilitation of patients with TMA. References 1. National Center for Health Statistics. National hospital discharge survey, Hyattsville, MD: National Center for Health Statistics, McKittrick LS, McKittrick JB, Risley TS. Transmetatarsal amputation for infection or gangrene in patients with diabetes mellitus. Ann Surg 1949; 130: Miller N, Dardik H, Wolodiger F, Pecoraro J, Kahn M, Ibrahim IM, et al. Transmetatarsal amputation: the role of adjunctive revascularization. J Vasc Surg 1991; 13: Lee JS, Lu M, Lee VS, Russell D, Bahr C, Lee ET. Lower-extremity amputation: incidence, risk factors, and mortality in the Oklahoma Indian Diabetes study. Diabetes 1993;42: Shun" DG, Cook TM. Prosthedcs and orthotics. Norwalk, CT: Appleton Lange, Durham JR, McCoy DM, Sawchuk AP, Meyer JP, Schwarz TH, Eldrup- Jorgensen J, et al. Open transmetatarsal amputation in the treatment of severe foot infections. Am J Surgery 1989; 158: Pecoraro RE, Reiber GE, Burgess EM. Pathways to diabetic limb amputadon: basis for prevention. Diabetes Care 1990; 13: Boulton AJM, Betts RP, Franks CI, Newrick PG, Ward JD, Duckworth T. Abnormalities of foot pressure in early diabetic neuropathy. Diabet Med 1987;4: Brand PW. The diabetic foot. In: Ellenberg M, Rifkin H, editors. Diabetes mellitus: theory and practice. 3rd rev. ed. New Hyde Park, NY: Medical Examination Publishing Co, 1983: Sage R, Pinzur MS, Cronin R, Preuss HF, Ostelman H. Complications following midfoot amputation in neuropathic and dysvascular feet. J Am Pod Med Assoc 1989;79: Hodge M J, Peters TG, Efird WG. Amputation of the distal portion of the foot. South Med J 1989;82: Sanders LJ, Dunlap G. Transmetatarsal amputation: a successful approach to limb salvage. J Am Pod Med Assoc 1992;82: Kozak GP. Diabetic foot disease: a major problem. In: Kozak GP, editor. Management of diabetic foot problems. Philadelphia: Saunders, 1984: Most RS, Sinnock P. The epidemiology of lower extremity amputation in diabetic individuals. Diabetes Care 1983;6: Mueller MJ, Diamond JE, Delitto A, Sinacore DR. Insensitivity, limited joint mobility, and plantar ulcers in patients with diabetes mellitus. Phys Ther 1989;69: Birke JA, Sims DS: Plantar sensory threshold in the Hansen's Disease ulcerative foot. Read at the Proceedings of the International Conference on Biomechanics and Clinical Kinesiology of Hand and Foot. Madras, India, December 16-18, Holewski JJ, Stress RM, Graf PM, Grunfeld L: Aesthesiometry: Quantification of cutaneous pressure sensation in diabetic peripheral neuropathy. J Rehab Res Dev 1988;25: Cavanagh PR, Derr JA, Ulbrecht JS, Maser RE, Orchard TJ. Problems in gait and posture in neuropathic patients with insulin-dependent diabetes mellitus. Diabet Med 1992;9: Mueller MJ, Minor SD, Sahrmann SA, Schaaf JA, Stlube MJ. Differences in the gait characteristics of patients with diabetes and peripheral neuropathy compared with age-matched controls. Phys Ther 1994; 74: Mueller MJ, Diamond JE, Sinacore DR, Delitto A, Blair VP, Drury DA, et al. Total contact casting in treatment of diabetic plantar ulcers: controlled clinical trim. Diabetes Care 1989; 12: Barry DC, Sabacinski KA, Habershaw GM, Giurini JM, Chrzan JS. Tendo achilles procedures for chronic ulcerations in patients with transmetatarsal amputations. J Am Pod Med Assoc 1993;83: Millstein SG, McCowan SA, Hunter GA. 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5 54 COMPLICATIONS AFTER AMPUTATION, Mueller 24. Cavanagh PR, Ulbrecht JS. Biomechanics of the foot in diabetes mellitus. In: Levin ME, O'Neal LW, Bowker JH, editors. The Diabetic Foot. 5th ed. St Louis: Mosby-Year Book, Schaff PS, Cavanagh PR. Shoes for the insensitive foot: the effect of a "rocker bottom" shoe modification on plantar pressure distribution. Foot Ankle 1990; 11: Nawoczenski DA, Birke JA, Coleman WC. Effect of rocker sole design on plantar forefoot pressures. J Am Pod Med Assoc 1988;78: Bauman JH, Girding J, Brand PW. Plantar pressures and trophic ulceration: an evaluation of footwear. J Bone Joint Surg [Br] 1963;45: Mueller M J, Sinacore DR. Rehabilitation factors following transmetarsal amputation: a clinical perspective. Phys Ther 1994;74: Mueller MJ, Sinacore DR, Hoogsrate S, Daly L. Effect of hip and ankle walking strategies on peak plantar pressures: implications for neuropathic ulceration. Arch Phys Med Rehab. In press. 30. Sims DR, Cavanagh PR, Ulbrecht JS. Risk factors in the diabetic foot; recognition and management. Phys Ther 1988; 12: Wooldridge J, Moreno L: Evaluation of the costs to Medicare of covering therapeutic shoes for diabetic patients. Diabetes Care 1994; 17: Edmonds ME, Blundell MP, Morris ME, Thomas EM, Cotton LT, Watkins PJ. Improved survival of the diabetic foot: the role of a specialized foot clinic. Q J Med 1986;232: Suppliers a. Aircast Inc., PO Box 709, Summit, NJ