The discovery of a relatively complete Australopithecus sediba adult female skeleton permits a detailed locomotor analysis in which joint systems can be integrated to form a comprehensive picture of ...gait kinematics in this late australopith. Here we describe the lower limb anatomy of Au. sediba and hypothesize that this species walked with a fully extended leg and with an inverted foot during the swing phase of bipedal walking. Initial contact of the lateral foot with the ground resulted in a large pronatory torque around the joints of the foot that caused extreme medial weight transfer (hyperpronation) into the toe-off phase of the gait cycle (late pronation). These bipedal mechanics are different from those often reconstructed for other australopiths and suggest that there may have been several forms of bipedalism during the Plio-Pleistocene.
OBJECTIVES:Estimating the likely success of limb revascularization in patients with lower-extremity arterial trauma is central to decisions between attempting limb salvage and amputation. However, ...the projected outcome is often unclear at the time these decisions need to be made, making them difficult and threatening sound judgement. The objective of this study was to develop and validate a prediction model that can quantify an individual patientʼs risk of failed revascularization.
METHODS:A BN prognostic model was developed using domain knowledge and data from the US joint trauma system. Performance (discrimination, calibration, and accuracy) was tested using ten-fold cross validation and externally validated on data from the UK Joint Theatre Trauma Registry. BN performance was compared to the mangled extremity severity score.
RESULTS:Rates of amputation performed because of nonviable limb tissue were 12.2% and 19.6% in the US joint trauma system (n = 508) and UK Joint Theatre Trauma Registry (n = 51) populations respectively. A 10-predictor BN accurately predicted failed revascularizationarea under the receiver operating characteristic curve (AUROC) 0.95, calibration slope 1.96, Brier score (BS) 0.05, and Brier skill score 0.50. The model maintained excellent performance in an external validation populationAUROC 0.97, calibration slope 1.72, Brier score 0.08, Brier skill score 0.58, and had significantly better performance than mangled extremity severity score at predicting the need for amputation AUROC 0.95 (0.92–0.98) vs 0.74 (0.67–0.80); P < 0.0001.
CONCLUSIONS:A BN (https://www.traumamodels.com) can accurately predict the outcome of limb revascularization at the time of initial wound evaluation. This information may complement clinical judgement, support rational and shared treatment decisions, and establish sensible treatment expectations.
Critical limb ischemia (CLI) is the most serious complication of peripheral artery disease (PAD).
The purpose of this study was to characterize pathology of PAD in below- and above-knee amputation ...specimens in patients presenting with CLI.
Peripheral arteries from 95 patients (121 amputation specimens) were examined; 75 patients had presented with CLI, and the remaining 20 had amputations performed for other reasons. The pathological characteristics were separately recorded for femoral and popliteal arteries (FEM-POP), and infrapopliteal arteries (INFRA-POP).
A total of 299 arteries were examined. In the 239 arteries from CLI patients, atherosclerotic plaques were more frequent in FEM-POP (23 of 34, 67.6%) compared with INFRA-POP (79 of 205, 38.5%) arteries. Of these 239 arteries, 165 (69%) showed ≥70% stenosis, which was due to significant pathological intimal thickening, fibroatheroma, fibrocalcific lesions, or restenosis in 45 of 165 (27.3%), or was due to luminal thrombi with (39 of 165, 23.6%) or without (81 of 165, 49.1%) significant atherosclerotic lesions. Presence of chronic luminal thrombi was more frequently observed in arteries with insignificant atherosclerosis (OR: 16.7; p = 0.0002), more so in INFRA-POP compared with FEM-POP (OR: 2.14; p = 0.0041) arteries. Acute thrombotic occlusion was less frequently encountered in INFRA-POP than FEM-POP arteries (OR: 0.27; p = 0.0067). Medial calcification was present in 170 of 239 (71.1%) large arteries.
Thrombotic luminal occlusion associated with insignificant atherosclerosis is commonly observed in CLI and suggests the possibility of atherothromboembolic disease. The pathological characteristics of arteries in CLI suggest possible mechanisms of progression of PAD to CLI, especially in INFRA-POP arteries, and may support the preventive role of antithrombotic agents.
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Patients with peripheral artery disease have an increased risk of cardiovascular morbidity and mortality. Antiplatelet agents are widely used to reduce these complications.
This was a multicentre, ...double-blind, randomised placebo-controlled trial for which patients were recruited at 602 hospitals, clinics, or community practices from 33 countries across six continents. Eligible patients had a history of peripheral artery disease of the lower extremities (previous peripheral bypass surgery or angioplasty, limb or foot amputation, intermittent claudication with objective evidence of peripheral artery disease), of the carotid arteries (previous carotid artery revascularisation or asymptomatic carotid artery stenosis of at least 50%), or coronary artery disease with an ankle–brachial index of less than 0·90. After a 30-day run-in period, patients were randomly assigned (1:1:1) to receive oral rivaroxaban (2·5 mg twice a day) plus aspirin (100 mg once a day), rivaroxaban twice a day (5 mg with aspirin placebo once a day), or to aspirin once a day (100 mg and rivaroxaban placebo twice a day). Randomisation was computer generated. Each treatment group was double dummy, and the patient, investigators, and central study staff were masked to treatment allocation. The primary outcome was cardiovascular death, myocardial infarction or stroke; the primary peripheral artery disease outcome was major adverse limb events including major amputation. This trial is registered with ClinicalTrials.gov, number NCT01776424, and is closed to new participants.
Between March 12, 2013, and May 10, 2016, we enrolled 7470 patients with peripheral artery disease from 558 centres. The combination of rivaroxaban plus aspirin compared with aspirin alone reduced the composite endpoint of cardiovascular death, myocardial infarction, or stroke (126 5% of 2492 vs 174 7% of 2504; hazard ratio HR 0·72, 95% CI 0·57–0·90, p=0·0047), and major adverse limb events including major amputation (32 1% vs 60 2%; HR 0·54 95% CI 0·35–0·82, p=0·0037). Rivaroxaban 5 mg twice a day compared with aspirin alone did not significantly reduce the composite endpoint (149 6% of 2474 vs 174 7% of 2504; HR 0·86, 95% CI 0·69–1·08, p=0·19), but reduced major adverse limb events including major amputation (40 2% vs 60 2%; HR 0·67, 95% CI 0·45–1·00, p=0·05). The median duration of treatment was 21 months. The use of the rivaroxaban plus aspirin combination increased major bleeding compared with the aspirin alone group (77 3% of 2492 vs 48 2% of 2504; HR 1·61, 95% CI 1·12–2·31, p=0·0089), which was mainly gastrointestinal. Similarly, major bleeding occurred in 79 (3%) of 2474 patients with rivaroxaban 5 mg, and in 48 (2%) of 2504 in the aspirin alone group (HR 1·68, 95% CI 1·17–2·40; p=0·0043).
Low-dose rivaroxaban taken twice a day plus aspirin once a day reduced major adverse cardiovascular and limb events when compared with aspirin alone. Although major bleeding was increased, fatal or critical organ bleeding was not. This combination therapy represents an important advance in the management of patients with peripheral artery disease. Rivaroxaban alone did not significantly reduce major adverse cardiovascular events compared with asprin alone, but reduced major adverse limb events and increased major bleeding.
Bayer AG.
Prediction of amputation wound healing is challenging due to the multifactorial nature of critical limb ischemia and lack of objective assessment tools. Up to one-third of amputations require ...revision to a more proximal level within 1 year. We tested a novel wound imaging system to predict amputation wound healing at initial evaluation.
Patients planned to undergo amputation due to critical limb ischemia were prospectively enrolled. Clinicians evaluated the patients in traditional fashion, and all clinical decisions for amputation level were determined by the clinician's judgement. Multispectral images of the lower extremity were obtained preoperatively using a novel wound imaging system. Clinicians were blinded to the machine analysis. A standardized wound healing assessment was performed on postoperative day 30 by physical exam to determine whether the amputation site achieved complete healing. If operative revision or higher level of amputation was required, this was undertaken based solely upon the provider's clinical judgement. A machine learning algorithm combining the multispectral imaging data with patient clinical risk factors was trained and tested using cross-validation to measure the wound imaging system's accuracy of predicting amputation wound healing.
A total of 22 patients undergoing 25 amputations (10 toe, five transmetatarsal, eight below-knee, and two above-knee amputations) were enrolled. Eleven amputations (44%) were non-healing after 30 days. The machine learning algorithm had 91% sensitivity and 86% specificity for prediction of non-healing amputation sites (area under curve, 0.89).
This pilot study suggests that a machine learning algorithm combining multispectral wound imaging with patient clinical risk factors may improve prediction of amputation wound healing and therefore decrease the need for reoperation and incidence of delayed healing. We propose that this, in turn, may offer significant cost savings to the patient and health system in addition to decreasing length of stay for patients.
Purpose
This longitudinal study examined the major physiological mechanisms that determine the age-related loss of lower extremity muscle power in two distinct groups of older humans. We hypothesized ...that after ~3 years of follow-up, mobility-limited older adults (mean age: 77.2 ± 4,
n
= 22, 12 females) would have significantly greater reductions in leg extensor muscle power compared to healthy older adults (74.1 ± 4,
n
= 26, 12 females).
Methods
Mid-thigh muscle size and composition were assessed using computed tomography. Neuromuscular activation was quantified using surface electromyography and vastus lateralis single muscle fibers were studied to evaluate intrinsic muscle contractile properties.
Results
At follow-up, the overall magnitude of muscle power loss was similar between groups: mobility-limited: −8.5 % vs. healthy older: −8.8 %,
P
> 0.8. Mobility-limited elders had significant reductions in muscle size (−3.8 %,
P
< 0.01) and strength (−5.9 %,
P
< 0.02), however, these parameters were preserved in healthy older (
P
≥ 0.7). Neuromuscular activation declined significantly within healthy older, but not in mobility-limited participants. Within both groups, the cross-sectional areas of type I and IIA muscle fibers were preserved while substantial increases in single fiber peak force (>30 %), peak power (>200 %) and unloaded shortening velocity (>50 %) were elicited at follow-up.
Conclusion
Different physiological mechanisms contribute to the loss of lower extremity muscle power in healthy older and mobility-limited older adults. Neuromuscular changes may be the critical early determinant of muscle power deficits with aging. In response to major whole muscle decrements, major compensatory mechanisms occur within the contractile properties of surviving single muscle fibers in an attempt to restore overall muscle power and function with advancing age.
Lower extremity free flap failure rates are higher than in other areas of the body. While prior studies assessed the effect of intraoperative technical variables, these generally investigated ...individual variables and did not examine relationships between the many individual technical decisions made during free tissue reconstruction. Our purpose was to investigate the effect of variation in intraoperative microsurgical techniques on flap outcomes in a diverse cohort of patients requiring lower extremity free flap coverage.
Consecutive patients undergoing free flap reconstruction of the lower extremity at two level 1 trauma centers from January 2002 to January 2020 were identified using Current Procedural Terminology codes, followed by a review of medical records. Information regarding demographics and comorbidities, indications, intraoperative technical details, and complications was collected. Outcomes of interest included an unplanned return to the operating room, arterial thrombosis, venous thrombosis, partial flap failure, and total flap failure. Bivariate analysis was performed.
In total, 410 patients underwent 420 free tissue transfers. The median follow-up time was 17 months (interquartile ranges: 8.0-37). Total flap failure occurred in 4.9% (
= 20), partial flap failure in 5.9% (
= 24), and unplanned reoperation in 9.0% (
= 37), with arterial thrombosis in 3.2% (
= 13) and venous thrombosis in 5.4% (
= 22). Overall complications were significantly associated with recipient artery choice, with arteries other than PT and AT/DP having a higher rate (
= 0.033), and with arterial revisions (
= 0.010). Total flap failure was also associated with revision of the arterial anastomosis (
= 0.035), and partial flap failure was associated with recipient artery choice (
= 0.032).
Many interoperative options and techniques are available when performing microvascular lower extremity reconstruction that leads to equally high success rates. However, the use of arterial inflow outside of the posterior tibial and anterior tibial arteries leads to a higher overall complication rate and partial flap failure rate. Intraoperative revision of the arterial anastomosis portends poorly for ultimate flap survival.
Limb salvage after lower extremity (LE) trauma requires optimal blood flow for successful microsurgical reconstruction. Peripheral arterial disease (PAD) decreases LE perfusion, affecting wound ...healing. Patients who present with LE trauma may have undiagnosed PAD, particularly those with atherosclerotic risk factors. This study assesses outcomes after LE salvage in patients at risk for PAD.
This retrospective review evaluated patients who underwent LE reconstruction at a level 1 trauma center between 2007 and 2022. Patients with a nontraumatic mechanism of injury, missing postoperative records, and unspecified race were excluded. Demographics, flap characteristics, and postoperative complications were abstracted. The prevalence of LE PAD was calculated using a validated risk assessment tool.
At our institution, 285 LE flaps performed on 254 patients were included in the study. Patients were categorized by prevalence of PAD, including 12 (4.7%) with high risk, 45 (17.7%) with intermediate risk, and 197 (77.6%) patients with low risk. The high-risk cohort had higher rates of partial flap necrosis ( P = 0.037), flap loss ( P = 0.006), and amputation ( P < 0.001) compared with the low-risk group. Fewer high-risk patients achieved full ambulation compared with the low-risk ( P = 0.005) cohort. Overall flap survival and limb salvage rates were 94.5% and 96.5%, respectively. Among the intermediate- and high-risk cohorts, only 50.9% of patients received a preoperative vascular assessment, and 3.8% received a vascular surgery consultation.
Peripheral arterial disease represents a reconstructive challenge to microvascular surgeons. Patients with high-risk for PAD had higher rates of partial flap necrosis, flap loss, and amputation. In the setting of trauma, emphasis should be placed on preoperative vascular assessment for patients at risk of having undiagnosed PAD. Prospective studies collecting ankle-brachial index assessments and/or angiography will help validate this study's findings.
To determine the rate of emergency versus elective lower extremity amputations in the United States.
Lower extremity amputation is a common endpoint for patients with poorly controlled diabetes and ...multilevel peripheral vascular disease. Although the procedure is ideally performed electively, patients with limited access may present later and require an emergency operation. To what extent rates of emergency amputation for lower extremities vary across the United States is unknown.
Evaluation of Medicare beneficiaries who underwent lower extremity amputation between 2015 and 2020. The rate was determined for each zip code and placed into rank order from lowest to highest rate. We merged each beneficiary's place of residence and location of care with the American Hospital Association Annual Survey using Google Maps Application Programming Interface to determine the travel distance for patients to undergo their procedure.
Of 233,084 patients, 66.3% (154,597) were men, 69.8% (162,786) were White. The average age (SD) was 74 years (8). There was wide variation in rates of emergency lower extremity amputation. The lowest quintile of zip codes demonstrated an emergency amputation rate of 3.7%, whereas the highest quintile demonstrated 90%. The median travel distance in the lowest emergency surgery rate quintile was 34.6 miles compared with 10.5 miles in the highest quintile of emergency surgery ( P < 0.001).
There is wide variation in the rate of emergency lower extremity amputations among Medicare beneficiaries, suggesting variable access to essential vascular care. Travel distance and rate of amputation have an inverse relationship, suggesting that barriers other than travel distance are playing a role.
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