Risk Factors for Lower Extremity Minor Amputation Conversion to Major Amputation.

BACKGROUND: Minor lower extremity amputations (LEAs) have become an important part of the limb salvage approach but are not as benign as previously thought. This study investigates the difference in outcome between toe/ray versus midfoot amputations and the risk factors for major amputation conversion associated with each procedure. METHODS: We performed retrospective chart review of foot amputation patients at a single tertiary care medical center with a primary end point of conversion to major amputation and secondary end points of 1-year wound healing and mortality rate. We collected data on relevant medical comorbidities, noninvasive vascular imaging, revascularization, repeat amputations, wound healing rate, and 1-year mortality. Patients were separated into toe/ray amputations versus midfoot amputation groups and compared using descriptive statistics, Chi-squared tests, Cox proportional hazards, and a multivariate logistic regression model. RESULTS: A total of 375 amputations were included in the analysis. 65.3% (245 patients) included toe/ray amputations and 34.7% (130 patients) included midfoot amputations. We compared these 2 cohorts with regard to their rate of conversion to repeat minor and/or major amputation in addition to overall mortality. The toe/ray group underwent more repeat minor amputations within 1 year after index amputation (34.7% vs. 21.5%, P = 0.008) and wound healing (epithelization) at 90 days was also higher in this group. The midfoot group had a higher conversion to major LEA within 1 year on univariate analysis (20.8 vs. 6.9%, P < 0.001). Overall 1-year mortality was 6.17% and there was no significant difference between groups. CONCLUSIONS: While there is a consistency with previous studies that found no significant overall difference in mortality between types of minor LEA, we have extended this previous work by demonstrating the independent risk factors for conversion to major amputation between types of minor LEA. Comparing these 2 groups will assist surgeons in choosing the appropriate level of amputations and will enhance patient's understanding of their chance of wound healing and risk of repeat amputation.

An investigational time course study of titanium plasma spray on osseointegration of PEEK and titanium implants: an in vivo ovine model.

BACKGROUND CONTEXT: Methods to improve osseointegration of orthopedic spinal implants remains a clinical challenge. Materials composed of poly-ether-ether-ketone (PEEK) and titanium are commonly used in orthopedic applications due to their inherent properties of biocompatibility. Titanium has a clinical reputation for durability and osseous affinity, and PEEK offers advantages of a modulus that approximates osseous structures and is radiolucent. The hypothesis for the current investigation was that a titanium plasma spray (TPS) coating may increase the rate and magnitude of circumferential and appositional trabecular osseointegration of PEEK and titanium implants versus uncoated controls. PURPOSE: Using an in vivo ovine model, the current investigation compared titanium plasma-sprayed PEEK and titanium dowels versus nonplasma-sprayed dowels. Using a time course study of 6 and 12 weeks postoperatively, experimental assays to quantify osseointegration included micro-computed tomography (microCT), biomechanical testing, and histomorphometry. STUDY DESIGN/SETTING: In-vivo ovine model. METHODS: Twelve skeletally mature crossbred sheep were equally randomized into postoperative periods of 6 and 12 weeks. Four types of dowel implants-PEEK, titanium plasma-sprayed PEEK (TPS PEEK), titanium, and titanium plasma-sprayed titanium (TPS titanium) were implanted into cylindrical metaphyseal defects in the distal femurs and proximal humeri (one defect per limb, n=48 sites). Sixteen nonoperative specimens (eight femurs and eight humeri) served as zero time-point controls. Half of the specimens underwent destructive biomechanical pullout testing and the remaining half quantitative microCT to quantify circumferential bone volume within 1 mm and 2 mm of the implant surface and histomorphometry to compute direct trabecular apposition. RESULTS: There were no intra- or perioperative complications. The TPS-coated implants demonstrated significantly higher peak loads at dowel pullout at 6 and 12 weeks compared with uncoated controls (p<.05). No differences were observed across dowel treatments at the zero time-point (p>.05). MicroCT results exhibited no significant differences in circumferential osseointegration between implants within 1 mm or 2 mm of the dowel surface (p>.05). Direct appositional osseointegration of trabecular bone based on histomorphometry was higher for TPS-coated groups, regardless of base material, compared with uncoated treatments at both time intervals (p<.05). CONCLUSIONS: The current in vivo study demonstrated the biological and mechanical advantages of plasma spray coatings. TPS improved histological incorporation and peak force required for implant extraction. CLINICAL SIGNIFICANCE: Plasma spray coatings may offer clinical benefit by improving biological fixation and osseointegration within the first 6 to 12 weeks postoperatively- the critical healing period for implant-based arthrodesis procedures.

Predictive Factors for Mortality Following Major Lower Extremity Amputation.

BACKGROUND: Despite advances in techniques and care, major amputation bears a high risk for mortality. Previously identified factors associated with increased risk of mortality include amputation level, renal function, and pre-operative white cell count. METHODS: A single center retrospective chart review was conducted identifying patients who had undergone a major amputation. Chi-squared, t-testing, and Cox proportional hazard modeling were performed examining death at 6 months and 12 months. RESULTS: Factors associated with an increased risk of six-month mortality include age (OR 1.01-1.05, P < .001), sex (OR 1.08-3.24, P < .01), minority race (OR 1.18-18.19, P < .01), chronic kidney disease (OR 1.40-6.06, P < .001), and use of pressors at the induction of anesthesia for index amputation (OR 2.09-7.85, P < .000). Factors associated with increased risk of 12 month mortality were similar. DISCUSSION: Patients undergoing major amputation continue to suffer high mortality. Those patients who received their amputation under physiologically stressful conditions were more likely to die within 6 months. Reliably predicting six-month mortality can assist surgeons and patients in making appropriate care decisions.

The Caged Knickerbocker: A Novel Modification to Targeted False Lumen Management in Complex Aortic Dissection.

INTRODUCTION: Targeted false lumen management has been described for complex presentations of aortic dissection. The "Knickerbocker" technique is often referenced and includes dilating a focal portion of an oversized endograft in the true lumen to purposefully rupture the false lumen septum, but at the expense of increased risk for visceral propagation and malperfusion. This case series describes a novel modification of the Knickerbocker technique by caging the distal end of the endograft prior to focal dilation. METHODS: A retrospective chart review was conducted at a tertiary academic center from 2018-2020. Patients were included if they had a history or current presentation of aortic dissection and underwent a Caged Knickerbocker (CKB) repair. Data were collected to include demographics, indications for repair, technical success, perioperative outcomes, hospital course, mortality, and further aortic interventions. RESULTS: Five patients were included in our evaluation. Four patients (80%) presented with chronic Type B aortic dissection (cTBAD) and concomitant aneurysmal degeneration of the thoracic aorta; 1 patient (20%) presented with an acute rupture secondary to cTBAD. Three patients (60%) had previous aortic repairs, 2 of which were for Type A Aortic Dissection that additionally required redo sternotomy and total arch replacement prior to CKB. CKB was technically successful in all cases with no peri-operative complications. Two (40%) patients required further aortic intervention due to aneurysmal degeneration. CONCLUSION: Achieving complete false lumen thrombosis is a considerable challenge when managing complex aortic dissections. Our data demonstrate the technical feasibly and early successful outcomes with the CKB approach. Importantly, CKB facilitates future distal extension into the para-visceral aorta in cases of complex thoracoabdominal aortic aneurysms. Further research should focus on discerning individual patients who will benefit from targeted false lumen management and compare outcomes between different approaches.

Open Proximal Endarterectomy with Retrograde Access and Stenting: A Novel Technique for Lower Extremity Revascularization.

BACKGROUND: Treatment of chronic limb threatening ischemia (CLTI) poses a significant clinical challenge despite recent medical advancements. Chronic total occlusion (CTO) lesions make endovascular approaches to CLTI particularly challenging. Open proximal exposure with retrograde access and stenting (OPERAS) aims to solve this challenge through retrograde subintimal crossing of a CTO with direct visualization of proximal re-entry into the true lumen. We describe this novel technique and present its efficacy in eight patients. METHODS: We conducted a retrospective case series at a single tertiary academic center. Data for patients who received OPERAS intervention included demographics, peri-operative details, and follow-up information. Statistical analysis was performed on length of stay, major post-operative complications, further intervention, clinical progression at 1 year, and amputation-free survival at 1 year. Immediate technical failure (ITF) and limb-based patency (LBP) at 1 year were calculated. RESULTS: Nine limbs underwent OPERAS between January 2019 and March 2020. Inflow was achieved with common femoral artery endarterectomy. All limbs underwent balloon angioplasty and stenting of the SFA, and seven underwent the same procedure in the popliteal artery. ITF was 0% for all nine cases. There were no major post-operative complications, and ankle-brachial index significantly improved pre-and post-operatively (P < .001). Eight limbs (88.9%) sustained amputation-free survival at 1 year, and overall LBP was 67% at 1 year. CONCLUSION: Our study presents a hybrid revascularization option to address severe, anatomically complex limbs (GLASS III) that lack a single autogenous conduit for open surgical revascularization. OPERAS addresses a main point of technical failure of subintimal techniques by directly visualizing the wire in the true lumen. Our data suggest that OPERAS can be effective to: (1) improve technical success of luminal re-entry following a subintimal approach; (2) address inflow concurrently with severe femoropopliteal disease; and (3) can be utilized when distal tissue loss is involved.

Patients value their own pain over braking safety when deciding when to return to driving: a discrete choice experiment on lower extremity injuries.

Objective: To quantify patient preferences towards time to return to driving relative to compromised reaction time and potential complication risks. Design: Cross-sectional discrete choice experiment. Setting: Academic trauma center. Patients: Ninety-six adult patients with an operative lower extremity fracture from December 2019 through December 2020. Intervention: None. Main Outcome Measurement: Patient completed a discrete choice experiment survey consisting of 12 hypothetical return to driving scenarios with varied attributes: time to return to driving (range: 1 to 6 months), risk of implant failure (range: 1% to 12%), pain upon driving return (range: none to severe), and driving safety measured by braking distance (range: 0 to 40 feet at 60 mph). The relative importance of each attribute is reported on a scale of 0% to 100%. Results: Patients most valued a reduced pain level when resuming driving (62%), followed by the risk of implant failure (17%), time to return to driving (13%), and braking safety (8%). Patients were indifferent to returning to driving at 1 month (median utility: 28, interquartile range [IQR] -31 to 80) or 2 months (median utility: 59, IQR: 41 to 91) postinjury. Conclusion: Patients with lower extremity injuries demonstrated a willingness to forego earlier return to driving if it might mean a decrease in their pain level. Patients are least concerned about their driving safety, instead placing higher value on their own pain level and chance of implant failure. The findings of this study are the first to rigorously quantify patient preferences toward a return to driving and heterogeneity in patient preferences. Level of Evidence: V.

Hip Fracture With Elevated Troponin: Harbinger of Mortality or Need for Accelerated Surgery?

OBJECTIVE: To determine the association of elevated troponin levels with time to surgery and the risk of mortality and other key clinical outcomes among elderly patients with hip fracture who had measured troponin levels at hospital admission. DESIGN: Retrospective cohort study. SETTING: Single academic trauma center. PATIENTS: We included 299 consecutive patients 60 years of age or older with a hip fracture and cardiac troponin levels measured at the time of hospital admission. INTERVENTION: Patients with elevated cardiac troponin levels at hospital admission (n = 43) compared with patients with normal troponin levels at admission (n = 256). MAIN OUTCOME MEASURES: Time to surgery, 90-day mortality, and major complications within 90 days of injury. RESULTS: The median age of the cohort was 80 years (interquartile range, 70-87 years), 59% were female, and 86% were living independently before their injury. Elevated troponin levels were associated with a 21-hour [95% confidence interval (CI), 12 to 32, P < 0.001] increase in the median time from admission to surgery (43 vs. 22 hours). Elevated troponin levels were also associated with a 14% (95% CI, 0% to 29%, P = 0.01) absolute increase in 90-day mortality (28% vs. 14%). Patients with elevated troponins were 15% (95% CI, -1% to 30%, P = 0.06) more likely to have a major complication (37% vs. 23%); however, the difference did not reach statistical significance. CONCLUSIONS: Among patients with a hip fracture and measured troponin levels, elevated troponin levels were associated with significant delays in surgery and increased 90-day mortality. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.