Success of transmetatarsal amputation for limb salvage in patients with peripheral artery disease

Abstract

Limb salvage is a difficult path for patients to travel as there is no guarantee of the outcome, often the major factor is perfusion. For patients who underwent transmetatarsal amputation (TMA), success rate is crucial as the next option is most likely a major amputation. We performed a 10 years (2010–2020) retrospective review of patients that underwent a TMA and had an angiogram or computed tomography angiography (CTA) perioperatively at the Dallas VA Medical Center. Failure after TMA was defined as a patient requiring a proximal amputation within 1 year. There were 125 TMAs performed between 2010 and 2020 at the institution. Forty‐four (35.2%) patients had an angiogram/CTA peri‐operative and met the inclusion criteria. Seventeen subjects (38.6%) had a higher level of amputation. Of the 17 failures, 2 (11.8%) patients had no patent vessel runoff to the foot, 9 (52.9%) had one vessel, 4 (23.5%) had two vessels, and 2 (11.8%) had three vessels runoff. One vessel runoff to the foot yielded a high rate of poor outcomes (56.3%) defined as a higher level of amputation. Two or more vessels runoff to the foot had over 75% success of limb salvage with a TMA.

1. INTRODUCTION

There are nearly 2 million people living with limb loss in the United States with the main cause of amputation being vascular disease (54%)—this includes patients with diabetes and peripheral arterial disease. ¹ Of this population, about half will die within 5 years, making the mortality rate of amputation higher than that of breast cancer, colon cancer, and prostate cancer. ² , ³ Furthermore, if the patient has diabetes, then up to 55% will require a contralateral amputation within 2–3 years. ⁴ This highlights the importance of limb salvage procedures.

As a limb salvage procedure, transmetatarsal amputation (TMA) is an attractive option because of the potential for good functional outcomes and no requirements for bracing. ⁵ , ⁶ TMA are mainly done in patients who have significant infection, deformity, or gangrene in the forefoot. However, there are no previous studies, to the authors' knowledge, that evaluate limb salvage success rate with TMA.

Most TMA incisions cross through three angiosomes (dorsalis pedis artery, medial plantar artery, and lateral plantar artery). ⁷ The dorsalis pedis artery, a branch of the anterior tibial (AT) artery, supplies the dorsal skin flap while the two plantar arteries supply the medial and lateral plantar flaps, which are branches of the posterior tibial (PT) artery. If there is only one patent vessel to the foot, then only the dorsal or plantar flap would receive direct blood flow to support wound healing. More importantly, if the patent single vessel was the peroneal artery, then the TMA site would be dependent on only collateral flow to heal the amputation site. We, therefore, hypothesize that limb salvage rates in patients undergoing transmetatarsal amputation with single‐vessel runoff is lower than in patients with 2 or 3 vessel runoff and that patients with single‐vessel peroneal artery runoff have lower limb salvage rates than those with single‐vessel anterior tibial or posterior tibial artery runoff.

2. METHOD

This study was approved by the Institutional Review Board. It was a retrospective review of all patients who presented to, underwent a TMA, and had an angiogram or computed tomography angiography (CTA) at the Dallas VA Medical Center from 2010 to 2020. Electronic medical records were used to extract the following data on the patients: laboratory data [white blood count (WBC), glycated hemoglobin (Hgb A1c), c‐reactive protein (CRP), estimated glomerular filtration rate (ESR), albumin, and pre‐albumin], treatment characteristics, demographic data, and co‐morbidities (congested heart disease, chronic kidney disease, coronary arterial disease, and diabetes). Failure of the TMA was defined as subjects that required a higher level of amputation (below‐knee or above‐knee amputation). Vitamin D deficiency was defined as <30 ng/mL. Failure after TMA was defined as a patient requiring a proximal amputation within 1 year.

Data were compiled using Microsoft Excel (Microsoft Corporation, Redmond, WA). Continuous data were reported as mean, median, 95% confidence intervals (CI), and standard deviation. A chi‐square test was used to compare dichotomous variables. A one‐way Analysis of Variance (ANOVA) was used to evaluate continuous variables, and the Mann–Whitney U Test was used for non‐parametric data. For all comparisons and modelling, the level of significance was set at p < 0.10 due to the low number of subjects. Data were analysed using calculators on www.socscistatistics.com.

3. RESULTS

Over 10 years, 125 TMAs were performed at the institution. Forty‐four patients (35.2%) had an angiogram/CTA peri‐operative; 29 patients (23.2%) had an ankle‐brachial index (ABI) done peri‐operative; and 52 patients (41.6%) had no pre‐operative vascular study [Figure 1]. Thus, 44 patients were included in the analysis, of which there were 17 TMA failed (38.6%).

FIGURE 1.

Breakdown of patients with TMA outcome between 2010 and 2020.

The most common co‐morbidities for the entire cohort were diabetes mellitus, heart disease (coronary arterial disease, congested heart failure), kidney disease, and vitamin D deficiency. When comparing co‐morbidities in patients with failed and successful TMA, there was no statistically significant difference between the two groups. Similarly, there was no significant difference in WBC, glycated hemoglobin, ESR, CRP, albumin, and pre‐albumin between patients who had failed compared to successful TMA [Table 1].

TABLE 1.

Laboratory values between patients who had angiogram and/or CTA.

	Failed TMA	Healed TMA	95% CI	OR	p‐value
n (Total = 44)	17 (38.6)	27 (61.4)
Male	17 (100)	27 (100)
Diabetes mellitus	11 (64.7)	24 (88.9)	0.05–1.09	0.23	0.05
Chronic kidney disease	5 (29.4)	8 (26.6)	0.26–3.74	0.99	0.99
On haemodialysis	3 (17.6)	6 (22.2)	0.16–3.51	0.75	0.71
Heart disease	8 (47.1)	14 (51.9)	0.24–2.78	0.83	0.76
Labs
White blood count	11.6, 10.7 (5.2)	11.9, 11 (4.8)	10.28–13.22		0.85
Erythrocyte sedimentation rate	67.3, 61 (32.8)	61, 65 (30.6)	56.18–80.98		0.85
C‐reactive protein	9.4, 9.3 (8.1)	6.8, 5.3 (5.0)	5.72–10.06		0.26
Glycated hemoglobin (%)	7.4, 6.8 (2.3)	7.3, 7.1 (1.4)	6.84–7.91		0.86
Albumin	2.8, 2.6 (0.7)	2.7, 2.7 (0.5)	2.57–2.91		0.78
Pre‐albumin	10.9, 9 (3.3)	11.8, 10.5 (5.1)	9.06–13.60		0.72
Vitamin D deficiency	9 (52.9)	7 (25.9)	0.89–11.6	3.21	0.70
Runoff vessels (AT, PT, Peroneal)
Zero/Unnamed vessel	2 (100)	0
One	9 (56.3)	7 (43.8)	0.89–11.6	3.21	0.07
Two	4 (17.6)	14 (77.8)	0.07–1.10	0.29	0.06
Three	2 (25)	6 (75)	0.08–2.64	0.47	0.38
Tarsal arch filled
Yes	6 (35.3)	13 (48.1)	0.17–2.05	0.59	0.40
No	3 (17.6)	4 (14.8)	0.24–6.34	1.23	0.80
Unknown	8 (47.1)	10 (37.0)	0.44–5.18	1.51	0.51
Pedal arch filled
Yes	3 (17.6)	7 (25.9)	0.13–2.79	0.61	0.52
No	7 (41.2)	13 (48.1)	0.22–2.57	0.75	0.65
Unknown	7 (41.2)	7 (25.9)	0.55–7.29	2	0.29

Note: Descriptive variables are represented as N (%). Continuous variables are represented as mean, median (standard deviation).

Abbreviations: 95% CI, 95% confidence interval; AT, anterior tibial artery; DM, diabetes mellitus; OR, odds ratio; PT, posterior tibial artery.

The most common indication for amputation was gangrene (81.8%), osteomyelitis (11.4%), and infection (4.5%) [Figure 2]. The mortality rate was 48.1% in patients with successful outcomes, and 41.2% in patients with failed outcomes [Figure 3].

FIGURE 2.

Diagnosis for TMA for cohort with angiogram/CTA.

FIGURE 3.

Overall number mortality of patients with TMA and had angiogram/CTA.

Of the 17 patients with failed TMA, 2 (11.8%) patients had no patent vessel runoff to the foot, 9 (52.9%) patients had one patent vessel, 4 (23.5%) patients had two patent vessels, and 2 (11.8%) patients had three patent vessels to the foot [Figure 4].

FIGURE 4.

Number of vessel runoff to the foot and the outcome.

4. DISCUSSION

Wound healing is a multifactorial process and while perfusion to the foot is one of the most important factors, there are other factors that play an important role as well. These include glycated hemoglobin, creatinine, estimated glomerular filtration rate, albumin, prealbumin, and vitamin D. Previous studies mainly evaluated limb salvage in term of critical limb ischemia. ⁸ , ⁹ , ¹⁰ , ¹¹ Johnson et al., found that after revascularization of the posterior tibialis artery, the limb salvage success rate was 91% at 1 year, but that decreased to 57% at 1 year. ¹¹ Dardik et al. found 84.2% limb salvage success rate with peroneal angioplasty. ⁸

Yammine et al. did a meta‐analysis reviewing the mortality rate of patients undergoing TMA and found that there is a mortality rate of 15.5% in 1 year, 23.5% in 3‐year, and 54.5% in 5‐year. ¹² Joyce et al. also reported a similar 5‐year mortality rate of 43% after a TMA. ¹³ Zambetti et al. performed an analysis of early failure of TMA, but they exclude patients who undergo additional procedures with the TMA. ¹⁴ The majority of TMA needed to be supplemented with Achilles tendon lengthening to prevent an increased forefoot pressure that would cause a breakdown of the surgical site and ulceration. By excluding additional procedures to the TMA in their study, they are evaluating patients who innately have higher risks for failure. Their study also does not look at perfusion as a cause of failure.

There are multiple studies that evaluate limb salvage success rate in patients with limb ischemia and wounds. ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸ , ¹⁹ , ²⁰ However, those studies are looking at different types of limb salvage. Anand et al. did a review of the literature on single vs multiple tibial artery revascularization in clinic limb ischemia and its limb salvage outcome. They found that single vessel intervention has no significant difference in wound healing and limb salvage vs multiple vessels interventions. ¹⁵ Soares et al. looked at the outcome of limb salvage based on how many infrapopliteal arteries were treated and found that it is more important to treat the most amendable artery as opposed to the number of arteries. ¹⁶ Varela et al. echoed similar findings and found that collateral flow through indirect revascularization (IR) yielded similar wound healing result to direct revascularization (DR). ¹⁷ However, these studies only evaluate patients who have foot wounds and not those who have TMA.

Kabra et al., Kret et al., and Elbadawy et al. all look at limb salvage from angiosome perspective. Kabra studied 69 patients who has single vessel runoff to the foot. In the DR group, 84% had success in limb salvage, and in the IR group, only 75% achieved limb salvaged. There was a 10.2% and 20% mortality rate at 6 months, respectively. Even though the result was not statistically significant (p = 0.06), the authors still recommend DR whenever possible. ¹⁸ Kret et al. looked at 106 limbs—54 DR and 52 IR. However, in their case, they found that there were statistical significance in both percentage of complete wound healing and time to healing in the DR group. Interestingly, the presence of a complete pedal plantar arch did not seem to influence wound healing. ¹⁹ Elbadawy et al. studied 212 patients and found superiority in DR over IR as well. ²⁰ This shows that angiosome direct revascularization has significant improvement in the outcome of limb salvage. It is important to point out that all these studies were done in patients with a foot wound, not TMA. A TMA incision crosses through multiple angiosomes in the foot. Thus, a DR would require successful intervention of both the anterior tibialis and posterior tibialis arteries to perfuse those angiosomes.

There are multiple studies looking at number of vessels runoff to the foot and/or angiosome‐directed intervention in term of limb salvage outcome in foot wound, but there are limited studies that evaluate limb salvage success rate with TMA. ²¹ , ²² , ²³ Zhang et al. reported TMA success rate in patients with DM is dependent on ABI. ²¹ With an ABI 0.7–0.9 had 87.8% success rate, ABI 0.41–0.69 had 35.5%, and ABI 0.4 only 11.1%. Marston et al. reported that ABI was independently associated with amputation at 1‐year and that ABI <0.5 has significant increased risk of amputation. ²² Pinzur et al. reported up to 92.2% limb salvage success rate after TMA if the patient's ABI >0.5, serum album >30 g/L, and a normal total lymphocyte count. ²³ However, if one or two of those criteria are below normal, then the success rate dropped to 38.5%.

Anecdotally, we have treated people with single‐vessel runoff to the foot and we have seen mixed results, with the majority resulting in surgical site dehiscence and requiring long‐term wound care. Some patients eventually ended up with a lower extremity amputation. If we can predict the success rate of limb salvage prior to surgery and educate the patient on the success rate of their procedure, then we can prevent those unnecessary procedures that have high likelihood of failure and spare the patient from the extensive process of local wound care that would ultimately result in a more proximal amputation. This prediction will help save the healthcare system from unnecessary expenditure of resources (operating room time, procedures, wound care supplies and products, skin grafts, home health, office visits, and hospital readmission for infection).

This is the first study to our knowledge that evaluate the success rate of TMA in patients with peripheral arterial disease with an assessment of the number of patent vessels to the foot. This study is interesting as it offered perspective into the success and failure rate of patients with PAD with the number of vessels runoff to the foot. The data showed that there was no statistical difference between the two groups in terms of co‐morbidities (except for diabetes), infection, and diagnosis. Interestingly, there were more patients with diabetes in the healed group, suggesting that diabetes may not play as important of a role in healing compared to perfusion. If we chose a p‐value of <0.10 (because of the low subject numbers), then we found a statistically significant between healed and failed TMA groups in patients with one‐ and two‐vessel runoffs. This study showed that if the patient has one‐vessel runoff to the foot, the patient is three times more likely to have failed TMA procedure with only a 43.8% success rate. However, if there are two‐vessels runoff to the foot, then the success rate of TMA increased to 77.8%.

The data in this study showed no difference in the limb salvage rate with regard to the presence or absence of tarsal and pedal arch filled. However, this is most likely because of the low subject number; thus, affecting the power analysis. The number of tarsal and pedal arch fill were too under power to confidently draw any conclusion from it [Figure 5]. The authors hypothesize that if pedal/tarsal arch filled is present, then the success rate will further increase as it will allow more perfusion to the soft tissue in the area.

FIGURE 5.

Patients with tarsal arch filled and outcome.

There are several limitations to this study. The first limitation is the retrospective nature of the study. Retrospective studies are often limited by the type and quality of data that are available for analysis. In this study, for instance, we had missing data on a large proportion of subjects regarding if there was filling of the arch observed on the angiogram. Not all patient with angiogram or CTA has a visible foot to be evaluated for presence of tarsal or pedal arch filled. Furthermore, since this was a 10‐years study, multiple providers from different services evaluated the study subjects. The operational definitions used to define important variables such as healing, infection, and criteria for proximal amputation were probably varied widely. For the earlier part of this retrospective review, a podiatrist was not involved in the care until more recently. In addition, this was a small study, and it was not powered adequately to measure s important variables. Selection bias may also be present as this study was conducted at a Veterans Affairs hospital; thus, it only offers care to veterans. Some veterans lived far away and may not be able to come to the hospital for care as frequently as other veterans who live closer. The population is disproportionately men. Our results therefore may not be generalizable to other populations.

In summary, if the patient has no vessel runoff to the foot, the success rate was extremely low. If there was only one vessel runoff to the foot, the patient has a 56.3% chance of failure that will result in a more proximal amputation. Two or more vessels runoff in the foot yielded over a 75% success rate in limb salvage after a TMA.

FUNDING INFORMATION

None.

CONFLICT OF INTEREST STATEMENT

None.

Truong DH, Ngoo AK, Tsai S, Yang AK, Wukich DK, Lavery LA. Success of transmetatarsal amputation for limb salvage in patients with peripheral artery disease. Int Wound J. 2024;21(1):e14360. doi: 10.1111/iwj.14360

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.