Predictors for reoperation after lower limb amputation in patients with peripheral arterial disease

Comparative evaluation of transcutaneous oxygen tension and ankle-brachial index as predictors of reoperation following below-knee amputation

OBJECTIVE

Decision-making regarding level of lower extremity amputation is sometimes challenging. Selecting an appropriate anatomic level for major amputation requires consideration of tradeoffs between postoperative function and risk of wound complications that may require additional operations, including debridement and/or conversion to above-knee amputation (AKA). We evaluated the utility of common, non-invasive diagnostic tests used in clinical practice to predict the need for reoperations among patients undergoing primary, elective, below knee-amputations (BKAs) by vascular surgeons.

METHODS

Patients undergoing elective BKA over a 5-year period were identified using Current Procedural Terminology codes. Medical records were reviewed to characterize demographics, pre-amputation testing transcutaneous oxygen tension (TcPO2), and ankle-brachial index (ABI). The need for ipsilateral post-BKA reoperation (including BKA revision and/or conversion to AKA) regardless of indication was the primary outcome. Associations were evaluated using univariable and multivariable logistic regression models. Cutpoints for TcPO2 values associated with amputation reoperation were evaluated using receiver operating characteristic curves.

RESULTS

We identified 175 BKAs, of which 46 (26.3%) required ipsilateral reoperation (18.9% BKA revisions and 14.3% conversions to AKA). The mean age was 63.3 ± 14.8 years. Most patients were male (65.1%) and White (72.0%). Mean pre-amputation calf TcPO2 was 40.0 ± 20.5 mmHg, and mean ABI was 0.64 ± 0.45. In univariable models, post-BKA reoperation was associated with calf TcPO2 (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.94-0.99; P = .013) but not ABI (OR, 0.53; 95% CI, 0.19-1.46; P = .217). Univariable associations with reoperation were also identified for age (OR, 0.97; 95% CI, 0.94-0.990; P = .003) and diabetes (OR, 0.43; 95% CI, 0.21-0.87; P = .019). No associations with amputation revision were identified for gender, race, end-stage renal disease, or preoperative antibiotics. Calf TcPO2 remained associated with post-BKA reoperation in a multivariable model (OR, 0.97; 95% CI, 0.94-0.99; P = .022) adjusted for age (OR, 0.98; 95% CI, 0.94-1.01; P = .222) and diabetes (OR, 0.98; 95% CI, 0.94-1.01; P = .559). Receiver operating characteristic analysis suggested a TcPO2 ≥38 mmHg as an appropriate cut-point for assessing risk for BKA revision (area under the curve = 0.682; negative predictive value, 0.91).

CONCLUSIONS

Reoperation after BKA is common, and reoperation risk was associated with pre-amputation TcPO2. For patients undergoing elective BKA, higher risk of reoperation should be discussed with patients with an ipsilateral TcPO2 <38 mmHg.

Quantification of Skeletal Muscle Perfusion in Peripheral Artery Disease Using 18F-Sodium Fluoride Positron Emission Tomography Imaging

BACKGROUND

Perfusion deficits contribute to symptom severity, morbidity, and death in peripheral artery disease (PAD); however, no standard method for quantifying absolute measures of skeletal muscle perfusion exists. This study sought to preclinically test and clinically translate a positron emission tomography (PET) imaging approach using an atherosclerosis-targeted radionuclide, fluorine-18-sodium fluoride (18F-NaF), to quantify absolute perfusion in PAD.

METHODS AND RESULTS

Eight Yorkshire pigs underwent unilateral femoral artery ligation and dynamic 18F-NaF PET/computed tomography imaging on the day of and 2 weeks after occlusion. Following 2-week imaging, calf muscles were harvested to quantify microvascular density. PET methodology was validated with microspheres in 4 additional pig studies and translated to patients with PAD (n=39) to quantify differences in calf perfusion across clinical symptoms/stages and perfusion responses in a case of revascularization. Associations between PET perfusion, ankle-brachial index, toe-brachial index, and toe pressure were assessed in relation to symptoms. 18F-NaF PET/computed tomography quantified significant deficits in calf perfusion in pigs following arterial occlusion and perfusion recovery 2 weeks after occlusion that coincided with increased muscle microvascular density. Additional studies confirmed that PET-derived perfusion measures agreed with microsphere-derived perfusion measures. Translation of imaging methods demonstrated significant decreases in calf perfusion with increasing severity of PAD and quantified perfusion responses to revascularization. Perfusion measures were also significantly associated with symptom severity, whereas traditional hemodynamic measures were not.

CONCLUSIONS

18F-NaF PET imaging quantifies perfusion deficits that correspond to clinical stages of PAD and represents a novel perfusion imaging strategy that could be partnered with atherosclerosis-targeted 18F-NaF PET imaging using a single radioisotope injection.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03622359.

Health Care Utilization After Major Limb Loss in Adults (18-64) Receiving Care in the Military Health System From 2001 to 2017

OBJECTIVE

To characterize and quantify health care utilization of Military Health System beneficiaries with major limb loss.

DESIGN

Retrospective cohort study.

SETTING

Military treatment facilities and civilian health care facilities that accept TRICARE insurance across the United States.

PARTICIPANTS

A total 5950 adult Military Health System beneficiaries with major limb amputation(s) acquired between January 1st, 2001, and September 30th, 2017 (N=5950).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

This study was an exploratory analysis designed to identify common care specialties, services, and devices utilized by Military Health System beneficiaries with major limb loss.

RESULTS

Most beneficiaries were retirees/dependents (63.3%), men (73.1%), and had a single amputation (88.7%), with a mean age of 42 years. Differences between beneficiary categories were found. Active-duty service members used a larger proportion of inpatient, emergency, primary care, physical and occupational therapy, prosthetics and orthotics, physical medicine and rehabilitation, and psychiatry services than retirees/dependents. Most common procedures included "revision of amputation stump" (57.2%) for the active-duty population and "other amputation below knee" (24.3%) for the retirees/dependents.

CONCLUSIONS

These findings highlight the rehabilitation trajectories of beneficiaries receiving treatment for major limb loss in military and civilian care settings. The results could inform staffing decisions and training programs for military treatment facilities, American trauma centers, rehabilitation hospitals, and outpatient health care providers treating individuals with amputation.

Does the advantage of transcutaneous oximetry measurements in diabetic foot ulcer apply equally to free flap reconstruction?

BACKGROUND

Transcutaneous oxygen pressure (TcpO₂) is a precise method for determining oxygen perfusion in wounded tissues. The device uses either electrochemical or optical sensors.

AIM

To evaluate the usefulness of TcpO₂ measurements on free flaps (FFs) in diabetic foot ulcers (DFUs).

METHODS

TcpO₂ was measured in 17 patients with DFUs who underwent anterolateral thigh (ALT)-FF surgery and compared with 30 patients with DFU without FF surgery.

RESULTS

Significant differences were observed in the ankle-brachial index; duration of diabetes; and haemoglobin, creatinine, and C-reactive protein levels between the two groups. TcpO₂ values were similar between two groups except on postoperative days 30 and 60 when the values in the ALT-FF group remained < 30 mmHg and did not increase > 50 mmHg.

CONCLUSION

Even if the flap is clinically stable, sympathectomy due to adventitia stripping during anastomosis and arteriovenous shunt progression due to diabetic polyneuropathy could lead to low TcpO₂ values in the ALT-FF owing to its thick fat tissues, which is supported by the slow recovery of the sympathetic tone following FF. Therefore, TcpO₂ measurements in patients with DFU who underwent FF reconstruction may be less accurate than in those who did not.

Determinants of healing and readiness for prosthetic fitting after transtibial amputation: Integrative literature review

BACKGROUND

Healing after an amputation is a critical step in the recovery process. Delayed wound healing can lead to deconditioning and flexion contractures which reduce a patient's ability to use a prosthesis, ambulate independently, and return to community participation. The purpose of this integrative literature review was to determine the evidence-based physiological factors, comorbidities, postoperative management, and outcome measures associated with healing after transtibial amputation and address how these factors clinically guide readiness for prosthetic intervention.

METHODS

Authors completed Google Scholar searches to identify the most effective search terms to locate salient publications. Authors also completed literature searches of Ovid MEDLINE and Epub Ahead of Print, In-Process, and Other Nonindexed Citations and Daily <1946 to August 6, 2020>; Embase Classic + Embase <1947 to August 6, 2020>; and CINAHL Complete <1946 to August 6, 2020> databases using the following search terms: "transtibial," "trans-tibial," "below knee," "BKA," "amputation," amputation stump," "amputee," "wound healing," and "heal/s/ed/ing." The authors decided to include all levels of evidence to capture the maximum number of articles related to the determinants of healing and readiness for prosthetic fitting after transtibial amputation.

RESULTS

The searches identified 2067 potential articles for review, and after removing articles not relevant to the topic, authors completed full-text assessment on 20 articles. These included review and synthesis on three randomized controlled trials and 12 cohort studies.

CONCLUSION

Preamputation assessment is most critical in patients who present with a longer list of comorbidities and suboptimal physiologic factors known to predict wound complications. Clinical judgment is most subjective when determining the degree of healing over time. Readiness for prosthetic treatment need not wait for complete healing of the residuum. Future research is needed to assess transcutaneous oxygen profusion along with other noninvasive measures of blood flow and perfusion as a more objective way to track progression of healing over time. This objective methodology would quantify healing, reduce subjectivity, and promote research to compare different enhanced recovery after surgery protocols for their impact on healing after amputation.

Mid- and Hindfoot Amputations in Diabetic Patients

Several surgical options exist to avoid or at least to delay a below-the-knee amputation (BKA). These are the so-called mid- or hindfoot amputations. They are a valuable treatment option in order to maintain the ability to ambulate without major auxiliary means (eg, a prosthesis). Hence, these amputations allow the patients to maintain certain autonomy. The acceptance of these amputations is significantly higher than a BKA, as the body image is less disturbed. The complication rate in hindfoot amputations in diabetic patients is high due to the comorbidities, in particular peripheral arterial disease and polyneuropathy.

The influence of primary and subsequent limb amputation on the overall rate of limb amputation in Saskatchewan, Canada, 2006-2019: a population-based study

Background

Understanding trends in limb amputation (LA) can provide insight into the prevention and optimization of health care delivery. We examine the influence of primary (first report) and subsequent (multiple reports) limb amputation on the overall (all reports) rate of limb amputation in Saskatchewan considering amputation level.

Methods

Hospital discharged data associated with LA from 2006 to 2019 and population estimates in Saskatchewan were used. LA cases were grouped based on overall, primary, and subsequent LA and further divided by level into major (through/above the ankle/wrist) and minor (below the ankle/wrist). Incidence rates were calculated using LA cases as the numerator and resident population as the denominator. Joinpoint and negative binomial were used to analyze the trends. In addition, the top three amputation predisposing factors (APF) were described by LA groups.

Results

The rate of overall LA and primary LA remained stable (AAPC − 0.9 [95% CI − 3.9 to 2.3]) and (AAPC −1.9 [95% CI −4.2 to 0.4]) respectively, while the rate of subsequent LA increased 3.2% (AAPC 3.2 [95% CI 3.1 to 9.9]) over the 14-year study period. The rate of overall major LA declined 4.6% (AAPC − 4.6 [95% CI −7.3 to −1.7]) and was largely driven by the 5.9% decline in the rate of primary major LA (AAPC − 5.9 [95% CI − 11.3 to –0.2]). Subsequent major LA remained stable over the study period (AAPC −0.4 [95% CI − 6.8 to 6.5]). In contrast, the overall rate of minor LA increased 2.0% (AAPC 2.0 [95% CI 1.0 to 2.9]) over the study period which was largely driven by a 9.6% increase in the rate of subsequent minor LA (AAPC 9.6 [95% CI 4.9 to 14.4]). Primary minor LA rates remained stable over the study period (AAPC 0.6 [95% CI − 0.2 to 1.5]). The study cohorts were 1.3-fold greater risk of minor LA than major LA. Diabetes mellitus (DM) was the leading APF representing 72.8% of the cohort followed by peripheral vascular disease (PVD) and trauma with 17.1 and 10.1% respectively. Most (86.7%) of subsequent LA were performed on people with DM.

Conclusions

Overall LA rates remained stable over the study period with declining rates of major LA countered by rising rates of minor LA. Minor LA exceeded major LA with the largest rate increase identified in subsequent minor LA. Diabetes was the greatest APF for all LA groups. This rising rate of more frequent and repeated minor LA may reflect changing intervention strategies implemented to maintain limb function. The importance of long-term surveillance to understand rates of major and minor LA considering primary and subsequent intervention is an important step to evaluate and initiate prevention and limb loss management programs.

Transtibial Amputation with Removal of the Tibial Intramedullary Nail: Hardware Removal in a Retrograde Manner

Transtibial amputation is the preferred strategy for treating a diabetic foot with an infection and necrosis. However, if a tibial intramedullary nail was previously inserted into the ipsilateral lower extremity, the nail must be removed to perform the transtibial amputation. In this special situation, the removal of the tibial intramedullary nail can cause various complications after transtibial amputation. We present a case and surgical technique report of a 46-year-old male with an uncontrolled diabetic foot with tibial intramedullary nail insertion. With the nail and ankle fixed by distal interlocking screws, a below-knee amputation was performed by removing the nail and the amputated limb together. This surgical method is expected to reduce postoperative complications such as infections and patella instability after the amputation of a diabetic foot.

What Is Currently the Role of TcPO2 in the Choice of the Amputation Level of Lower Limbs? A Comprehensive Review

Some patients still require major amputation for lower extremity peripheral arterial disease treatment. The purpose of pre-operative amputation level selection is to determine the most distal amputation site with the highest healing probability without re-amputation. Transcutaneous oximetry (TcPO2) can detect viable tissue with the highest probability of healing. Several factors affect the accuracy of TcPO2; nevertheless, surgeons rely on TcPO2 values to determine the optimal amputation level. Background about the development of TcPO2, methods of measurement, consequences of lower limb amputation level, and the place of TcPO2 in the choice of the amputation level are reviewed herein. Most of the retrospective studies indicated that calf TcPO2 values greater than 40 mmHg were associated with a high percentage of successful wound healing after below-knee-amputation, whereas values lower than 20 mmHg indicated an increased risk of unsuccessful healing. However, a consensus on the precise cut-off value of TcPO2 necessary to assure healing is missing. Ways of improvement for TcPO2 performance applied to the optimization of the amputation-level are reported herein. Further prospective data are needed to better approach a TcPO2 value that will promise an acceptable risk of re-amputation. Standardized TcPO2 measurement is crucial to ensure quality of data.