Risk Factors for Wound Complications Following Transmetatarsal Amputation in Patients With Diabetes

Comparing perioperative outcomes after transmetatarsal amputation in patients with or without peripheral vascular disease

BACKGROUND

Transmetatarsal amputation (TMA) is a commonly performed procedure for gangrene in the setting of diabetes or peripheral vascular disease. The purpose of this study is to investigate the incidence of and risk factors for reoperation and perioperative complications after TMA in patients undergoing surgery for primarily infectious/diabetic wounds versus peripheral vascular disease.

METHODS

Patients undergoing TMA between January 1, 2015 and December 31, 2020 were identified using the American College of Surgeons National Surgical Quality Improvement Program database. The indication for surgery was reported using the International Classification of Disease 9/10 codes. Patients were categorized into two groups: patients undergoing surgery for primarily infectious/diabetic wounds versus peripheral vascular disease. The incidence of 30-day mortality, readmission, reoperation, nonhome discharge, and various medical and surgical complications was reported. Outcome measures were compared between the diabetic and peripheral vascular disease groups. Logistic regression was used to identify independent risk factors for each outcome measure of interest.

RESULTS

3392 patients were included in the final cohort. There was a 30-day mortality rate of 2.9%, reoperation rate of 13.8%, readmission rate of 16.8%, surgical complication rate of 22.2%, and medical complication rate of 15.8%. Patients undergoing surgery for a vascular indication had a higher rate of mortality, reoperation, hospital readmission, nonhome discharge, and various medical complications (p < 0.05). Patients undergoing surgery for infectious/diabetic wounds had a higher rate of deep surgical site infection and systemic sepsis (p < 0.05). A vascular surgical indication was independently associated with reoperation and overall medical complications (p < 0.05). Various factors, including age, body mass index, medical comorbidities, and the presence of preoperative sepsis were associated with poor outcomes.

CONCLUSION

Significant rates of mortality, reoperation, and hospital readmission were reported after TMA. The presence of peripheral vascular disease was independently associated with reoperation and medical complications. Patients undergoing TMA, particularly for peripheral vascular disease, should be counseled about perioperative risks and indicated for surgery carefully.

Risk Factors Associated with Failure of Toe Amputation in Diabetic Foot Infections

We aim to identify the factors associated with the failure of amputation of one to three toes (index toe amputation) in patients with diabetes and foot infection. We conducted a retrospective cohort of 175 patients with diabetes who were hospitalized for moderate to severe foot infection and underwent amputation of one to three toes. A Poisson regression model was used to determine the prevalence ratio (PR) as a measure of association. The mean age was 63.3 ± 11.4 years. Fifty-three patients presented failure after undergoing toe amputation (30.3%). Multivariate analysis, adjusted for age and sex, showed the following significant variables: severe infection (PR: 1.78; 95% confidence interval [CI]: 1.14-2.78; P = 0.011), infection by Escherichia coli (PR: 2.21; 95% CI: 1.42-3.43; P < 0.001), infection by Pseudomonas aeruginosa (PR: 2.11; 95% CI: 1.29-3.43; P = 0.003) and prothrombin time (PR: 1.13; 95% CI: 1.05-1.21; P = 0.001), obesity (PR: 0.58; 95% CI: 0.37-0.93; P = 0.024), and haemoglobin value (PR: 0.92; 95% CI: 0.86-0.99; P = 0.023). About one-third of patients who underwent amputation of one to three toes for diabetic foot infection presented a failure and required a more proximal surgery. Severe infections, isolation of Pseudomonas aeruginosa and Escherichia coli, and prolonged prothrombin time were associated with a higher prevalence of failure. However, obesity and an elevated haemoglobin level were associated with a lower prevalence of failure.

Above-ankle Reamputation and Mortality following Transmetatarsal Amputation in Diabetic and Nondiabetic Peripheral Artery Disease

The risk of above-ankle reamputation following a transmetatarsal amputation is around 30%. Patient selection may be crucial to achieve good outcomes, and to avoid futile operations and suffering. We are aware of no previous comparison between the two largest patient groups that undergo lower extremity amputations: patients with diabetes, and patients with non-diabetic peripheral artery disease. Patients with diabetes or nondiabetic peripheral artery disease who had undergone a transmetatarsal amputation from 2004 to 2018 at our institution were included. Patient characteristics and perioperative details were analyzed retrospectively. Subjects with diabetes were compared with subjects with nondiabetic peripheral artery disease regarding above-ankle reamputation, reamputation level, and mortality. Five-hundred-and-sixty transmetatarsal amputations in 513 subjects were included. The majority of transmetatarsal amputations (86%) occurred in diabetic subjects. Subjects with non-diabetic PAD had a higher risk of above-ankle reamputation (p = .008), and death (p < .001). At the time of data collection, only multiple-ray amputation (vs. single-ray) was an independent risk factor for above-ankle reamputation. Only age, medical comorbidity in general, and chronic heart failure were independent risk factors of death. To our knowledge, this study is the first to report marked differences in above-ankle reamputation rates and mortality following transmetatarsal amputation, comparing diabetics with non-diabetic patients with peripheral artery disease. However, the differences may be attributed to non-diabetics being older, having more medical comorbidities, and having more advanced foot ulcers at the time of transmetatarsal amputation. In patients exhibiting several of these risk factors, transmetatarsal amputation may be futile.

Morbidity and Mortality of the Transmetatarsal Amputation: A Comparative NSQIP Analysis

The objective of this investigation was to compare the morbidity and mortality of transmetatarsal amputation to other frequently performed surgical procedures utilizing a large US database. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was interrogated for the purposes of this investigation. We initially extracted data related to the Current Procedural Terminology (CPT) code 28805 (amputation, foot; transmetatarsal) and the variable labels "estimated probability of morbidity" and "estimated probability of mortality." We subsequently performed a CPT code search for those procedures occurring at a frequency greater than 10,000 in the database, and additionally extracted data for estimated probability of morbidity and estimated probability of mortality for these procedures. This resulted in identification of 17 additional procedures. CPT code 28805 was associated with the highest estimated probability of morbidity of the cohort (0.1360 ± 0.0669), and this demonstrated statistical significance higher than all other CPT codes (p < .001). CPT code 28805 was associated with the second-highest estimated probability of mortality of the cohort (0.0327 ± 0.0596). This demonstrated statistical significance less than that of CPT code 27245 (0.0327 ± 0.0596 vs 0.0547 ± 0.0661; p < .0001), but statistical significance higher than all other CPT codes (p<0.001). The results of this investigation indicate that transmetatarsal amputation carries a substantial risk for morbidity and mortality in comparison to other commonly performed surgical procedures.

Risk Factors for a Failed Transmetatarsal Amputation in Patients with Diabetes

BACKGROUND

Transmetatarsal amputation (TMA) is a well-recognized limb-salvage procedure, often indicated for the treatment of diabetic foot infections. Currently, there is no widespread agreement in the literature with regard to the factors associated with failure of TMA. This study aimed to define risk factors for the failure of TMA, defined as below-the-knee or above-the-knee amputation, in patients with diabetes.

METHODS

This retrospective cohort study included 341 patients who underwent primary TMA. Patients who had a revision to a higher level (the failed TMA group) were compared with those who did not have failure of the initial amputation (the successful TMA group).

RESULTS

This study showed a higher frequency of renal impairment, defined as a high creatinine level and/or a previous kidney transplant or need for dialysis, in the failed TMA group (p = 0.002 for both). Furthermore, a Charlson Comorbidity Index (CCI) threshold value of 7.5 was identified as the optimal predictive value for failure of TMA (p = 0.002), and patients with a CCI of >7.5 had a median time of 1.13 months until the initial amputation failed.

CONCLUSIONS

TMA is associated with a high risk of revision. CCI may be used as a preoperative selection criterion, as 71.8% of patients with a CCI of >7.5 had failure of the TMA.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Remnant Metatarsal Parabola Structure on Transmetatarsal Amputation Primary Healing and Durability

Although generally considered to be both a durable and functional procedure for limb preservation, the transmetatarsal amputation (TMA) has high rates of complication, failure, revisional operation, and progression to more proximal amputation. The objective of this investigation was to determine the effect of remnant metatarsal parabola structure on healing outcomes following TMA. A retrospective chart review was performed of subjects undergoing a complete TMA with primary closure. We considered 4 patterns of remnant metatarsal parabola structure. TMA pattern type 1 was a normal parabola with the remnant second metatarsal extending furthest distally and slightly longer than the remnant first and third metatarsals with a gradual lateral taper. TMA pattern type 2 was the first metatarsal remnant extending furthest distally with a gradual lateral taper. TMA pattern type 3 was a relatively long fifth metatarsal remnant without the presence of a gradual lateral taper. And TMA pattern type 4 was a relatively short first metatarsal remnant with a relatively long second metatarsal with a gradual lateral taper. Seventy-three transmetatarsal amputations in 73 subjects met selection criteria. Thirty-nine (53.4%) amputations healed primarily at 90 days. No statistically significant differences were observed between groups with respect to the 90-day primary healing rate (p = .571) or 1-year ambulation rate without wound recurrence or reoperation (p = .811). These results might indicate that the remnant metatarsal structure does not have an effect on transmetatarsal amputation outcome. It is our hope that these results add to the body of knowledge and lead to further investigations into outcomes of limb preservation surgical interventions.

A Comparison of Adverse Short-Term Outcomes Following Forefoot Amputation Performed on an Inpatient Versus Outpatient Basis

The objective of this investigation was to evaluate short-term adverse outcomes following forefoot amputation with a specific comparison between those procedures performed on an inpatient versus outpatient basis. The 2018 American College of Surgeons National Surgical Quality Improvement Program database was interrogated to select those subjects with a 28805 current procedural terminology code (amputation, foot; transmetatarsal) that underwent the procedure with "all layers of incision (deep and superficial) fully closed." This resulted in 326 subjects who underwent the procedure on an inpatient basis and 72 subjects who underwent the procedure on an outpatient basis. Results of the primary outcome measures found no significant differences between groups with respect to the development of a superficial surgical site infection (5.8% vs 5.6%; p = .950), deep incisional infection (3.4% vs 5.6%; p = .380), or wound disruption (3.4% vs 6.9%; p = .163). Additionally, no significant differences were observed between groups with respect to unplanned reoperations (15.6% vs 12.5%; p = .500) or unplanned hospital readmissions (21.8% vs 23.6%; p = .957). The results of this investigation demonstrate no difference in short-term adverse outcomes following the performance of forefoot amputation with primary closure when the procedure is performed on an inpatient or outpatient basis. We hope that this information is utilized in future investigations specifically examining this clinical scenario as it relates to hospital admission criteria related to lower extremity tissue loss, length of hospital stay considerations, the timing of partial foot amputation following revascularization, and the economics of limb preservation.

Transmetatarsal Amputation Outcomes When Utilized to Address Foot Gangrene and Infection: A Retrospective Chart Review

A transmetatarsal amputation (TMA) is a widely utilized procedure to address foot gangrene and infection. Although a common procedure, so too are the associated complications. The purpose of this review was to evaluate TMA healing and to explore if there were associated variables correlating with healed vs. failed to heal TMA sites. To do so, the Medical Department Orthopaedics Division Electronic Database, West Virginia University, College of Medicine was retrospectively searched to identify all cases of TMAs (CPT code 28805) during the period of January 2011 through June 2019, and those variables that might impact TMA healing. Then both univariate and multivariable logistic regression analyses were performed to investigate the associations between these variables and TMA healing, and sensitivity analyses were also conducted to determine if the results resisted the influence of one unmeasured confounder. There were 39 patients (41 procedures) who would undergo a TMA. The mean average patient age was 53 (range 29-73) years old. The median postoperative follow-up period was 617 (range 199-3632) days. TMA mortality data revealed 0 deaths at 30 days, 2 (5.1%) at 1 year, 8 (20.5%) at 5 years. In our study, 29 (70.7%) of the TMAs would achieve primary healing at a median of 31 (range 16-253) days. When comparing the TMA healed group to the failed to heal group the following independent variables were considered: diabetes mellitus, HgA1c >8%, neuropathy, peripheral arterial disease, chronic kidney disease, active smoking status, previous surgery, and a clean margin metatarsal bone pathology specimen positive for osteomyelitis. Of the aforementioned, only neuropathy (odds ratio [OR] = 0.056, 95% confidence interval [CI] = 0-0.501, p = .0062) and positive bone margin (OR = 0.144, 95% CI = 0.022-0.835, p = .0385) were found to be significant in univariate logistic regression analysis. In multivariable logistic regression analyses where the potential confounders age, gender, and body mass index were accounted for, of the 8 independent variables of interest, only neuropathy (OR = 0.037, 95% CI = 0-0.497, p = .0036) remained significantly associated with the healing status. Neuropathy was present in 17 (58.6%) of the healed TMAs and in 12 (100%) of the failed to heal TMAs. However, the positive bone margin failed to reach statistical significance (OR = 0.079, 95% CI = 0-1.39, p = .1331). Results from another multivariable logistic regression model where a quadratic term for age was added revealed that positive bone specimen correlated with the TMA healing status with significance (OR = 0.051, 95% CI = 0.001- 0.560, p = .0404). A positive clean margin bone specimen was found in 3 (10.3%) of the healed TMAs and in 4 (44.4%) of the failed to heal TMAs. The sensitivity analysis where current ulceration was used as an unmeasured confounder indicated that the results regarding the association between neuropathy or positive bone margin and TMA healing, though inconclusive, resisted the influence of this unmeasured confounder. Hopefully these findings will be a beneficial addition to the current TMA literature and as such, further assist with informed surgical decision making.