Improved long-term functional outcomes and mortality of patients with vascular-related amputations utilizing the lower extremity amputation pathway.

BACKGROUND: Enhanced recovery after surgery pathways lead to improve perioperative outcomes for patients with vascular-related amputations; however, long-term data and functional outcomes are lacking. This study evaluated patients treated by the lower extremity amputation pathway (LEAP) and identified predictors of ambulation. METHODS: A retrospective review of LEAP patients who underwent major amputation from 2016 to 2022 for Wound, Ischemia, and foot Infection stage V disease was performed. LEAP patients were matched 1:1 with retrospective controls (NOLEAP) by hospital, need for guillotine amputation, and final amputation type (above knee vs below knee). The primary end point was the Medicare Functional Classification Level (K level) (functional classification of patients with amputations) at the last follow-up. RESULTS: We included 126 patients with vascular-related amputations (63 LEAP and 63 NOLEAP). Seventy-one percent of the patients were male and 49% were Hispanic with a mean state Area Deprivation Index of 9/10. There were no differences in baseline demographics or comorbidities. All patients had a K level of >0 (ambulatory) before amputation and an average Modified Frailty Index of 4. The median follow-up was 270 days (interquartile range, 84-1234 days) in the NOLEAP group and 369 days (interquartile range, 145-481 days) in the LEAP group. Compared with NOLEAP patients, LEAP patients were more likely to receive a prosthesis (86% vs 44%;P > .001). LEAP patients were more likely to have a K level of >0 (60% vs 25%; P = .003). On multivariable logistic regression, participation in LEAP increased the odds of a K level of >0 at follow-up by 5.8-fold (odds ratio, 5.8; 95% confidence interval, 2.5-13.6). Patients with a K level of >0 had significantly higher survival at 4 years (93% vs 59%; P = .001). In a Cox proportional hazards model, adjusted for demographics, comorbidities and amputation level, a K level of >0 at follow-up was associated with an 88% decrease in the risk of mortality compared with a K level of 0. CONCLUSIONS: LEAP leads to improved ambulation with a prosthesis in a socioeconomically disadvantaged and frail patient population. Patients with a K level of >0 (ambulatory) have significantly improved mortality.

Oxidative metabolism is impaired by phosphate deficiency during fracture healing and is mechanistically related to BMP induced chondrocyte differentiation.

Prior studies of acute phosphate restriction during the endochondral phase of fracture healing showed delayed chondrocyte differentiation was mechanistically linked to decreased bone morphogenetic protein signaling. In the present study, transcriptomic analysis of fracture callus gene expression in three strains of mice was used to identify differentially expressed (FDR = q ≤ 0.05) genes in response to phosphate (Pi) restriction. Ontology and pathway analysis of these genes showed that independent of genetic background, a Pi-deficient diet downregulated (p = 3.16 × 10-23) genes associated with mitochondrial oxidative phosphorylation pathways as well as multiple other pathways of intermediate metabolism. Temporal clustering was used to identify co-regulation of these specific pathways. This analysis showed that specific Ox/Phos, tricarboxylic acid cycle, pyruvate dehydrogenase. Arginine, proline metabolism genes, and prolyl 4-hydroxylase were all co-regulated in response to dietary Pi restriction. The murine C3H10T½ mesenchymal stem cell line was used to assess the functional relationships between BMP2-induced chondrogenic differentiation, oxidative metabolism and extracellular matrix formation. BMP2-induced chondrogenic differentiation of C3H10T½ was carried out in culture media in the absence or presence of ascorbic acid, the necessary co-factor for proly hydroxylation, and in media with normal and 25 % phosphate levels. BMP2 treatment led to decreased proliferation, increased protein accumulation and increased collagen and aggrecan gene expression. Across all conditions, BMP2 increased total oxidative activity and ATP synthesis. Under all conditions, the presence of ascorbate further increased total protein accumulation, proly-hydroxylation and aggrecan gene expression, oxidative capacity and ATP production. Lower phosphate levels only diminished aggrecan gene expression with no other effects of metabolic activity being observed. These data suggest that dietary phosphate restriction controls endochondral growth in vivo indirectly through BMP signaling, which upregulates oxidative activity that is linked to overall protein production and collagen hydroxylation.

Community-wide feasibility of the Lower Extremity Amputation Protocol amongst vascular amputees.

BACKGROUND: The Lower Extremity Amputation Protocol (LEAP) is a multidisciplinary enhanced recovery after surgery pathway for vascular amputees. The objective of this study was to examine feasibility and outcomes of community-wide implementation of LEAP. METHODS: LEAP was implemented at three safety net hospitals for patients with peripheral artery disease or diabetes requiring major lower extremity amputation. Patients who underwent LEAP (LEAP) were matched 1:1 with retrospective controls (NOLEAP) on hospital location, need for initial guillotine amputation, and final amputation type (above- vs below-knee). Primary endpoint was postoperative hospital length of stay (PO-LOS). RESULTS: A total of 126 amputees (63 LEAP and 63 NOLEAP) were included with no difference between baseline demographics and co-morbidities between the groups. After matching, both groups had the same prevalence of amputation level (76% below-knee vs 24% above-knee). LEAP patients had shorter duration of postamputation bed rest (P = .003) and were more likely to receive limb protectors (100% vs 40%; P ≤ .001), prosthetic counseling (100% vs 14%; P ≤ .001), perioperative nerve blocks (75% vs 25%; P ≤ .001), and postoperative gabapentin (79% vs 50%; P ≤ .001). Compared with NOLEAP, LEAP patients were more likely to be discharged to an acute rehabilitation facility (70% vs 44%; P = .009) and less likely to be discharged to a skilled nursing facility (14% vs 35%; P = .009). The median PO-LOS for the overall cohort was 4 days. LEAP patients had a shorter median PO-LOS (3 [interquartile range, 2-5] vs 5 [interquartile range, 4-9] days; P < .001). On multivariable logistic regression, LEAP decreased the odds of a PO-LOS of ≥4 days by 77% (odds ratio, 0.23; 95% confidence interval, 0.09-0.63). Overall, LEAP patients were significantly less likely to have phantom limb pain (5% vs 21%; P = .02) and were more likely to receive a prosthesis (81% vs 40%; P ≤ .001). In a multivariable Cox proportional hazards model, LEAP was associated with an 84% reduction in time to receipt of prosthesis (hazard ratio, 0.16; 95% confidence interval, 0.085-0.303; P < .001). CONCLUSIONS: Community wide implementation of LEAP significantly improved outcomes for vascular amputees demonstrating that utilization of core ERAS principles in vascular patients leads to decreased PO-LOS and improved pain control. LEAP also affords this socioeconomically disadvantaged population a greater opportunity to receive a prosthesis and return to the community as a functional ambulator.

Lower extremity amputation protocol: a pilot enhanced recovery pathway for vascular amputees.

Vascular patients, an inherently older, frail population, account for >80% of major lower extremity amputations (transtibial or transfemoral) in the United States. Retrospective data have shown that early physical therapy and discharge to an acute rehabilitation facility decreases the postoperative length of stay (LOS) and expedites ambulation. In the present study, we sought to determine whether patients treated with the lower extremity amputation protocol (LEAP) will have improved outcomes. We performed a nonrandomized prospective study of vascular patients undergoing an amputation from January 2019 to February 2020. Patients who were nonambulatory or had undergone a previous contralateral major amputation were excluded. LEAP is a multidisciplinary team approach to the perioperative care of amputees using an outlined protocol. The prospective patients were compared with historic controls treated before the initiation of LEAP (January 2016 to December 2018). The primary outcomes included the postoperative LOS, time to receipt of a prosthesis, and time to ambulation. Of the 141 included patients, 130 were in the retrospective group and 11 in the LEAP group. The demographics and comorbidities were similar. All 11 LEAP patients had undergone a below-the-knee amputation, with 1 requiring revision to an above-the-knee amputation. Of the 130 retrospective patients, 122 (94%) had undergone a below-the-knee amputation, with 1 requiring revision to an above-the-knee amputation. The LEAP patients were more likely to be discharged to acute rehabilitation (100% vs 27%; P < .001), receive a prosthesis (100% vs 45%; P < .001), and ambulate with the prosthesis (100% vs 43%; P < .001). The LEAP patients had received physical therapy 2 days sooner than had the retrospective controls (P = .006) with a shorter postoperative LOS (3 days vs 6 days; P < .001). Of the patients who had received their prosthesis, the LEAP patients had received their prosthesis, on average, 2 months sooner than had the retrospective cohort (81 ± 39 days vs 137 ± 97 days, respectively; P = .002) and had ambulated with their prosthesis sooner (86 ± 53 days vs 146 ± 104 days, respectively; P = .002). No differences were found in the incidence of surgical site complications or unplanned readmissions between the two groups. The results from the present pilot study have demonstrated that the use of LEAP can significantly decrease postoperative LOS and expedite the time to independent ambulation with a prosthesis for vascular patients undergoing a major lower extremity amputation. These findings suggest a powerful ability to bridge the healthcare gap for this high-risk, underserved, and ethnically diverse population using a disease-specific standardized protocol.

Serum proteomic assessment of the progression of fracture healing.

A targeted proteomic analysis of murine serum over a 35-day course of fracture healing was carried out to determine if serum proteomic changes could be used to monitor the biological progression of fracture healing. Transverse, closed femoral fractures where generated and stabilized with intramedullary fixation. A single stranded DNA aptamer-based multiplexed proteomic approach was used to assay 1,310 proteins. The transcriptomic profiles for genes matching the 1,310 proteins were obtained by microarray analysis of callus mRNA. Of the 1,310 proteins analyzed, 850 proteins showed significant differences among the time points (p-value <0.05). Ontology assessment associated these proteins with osteoblasts, monocyte/macrophage lineages, mesenchymal stem cell lines, hepatic tissues, and lymphocytes. Temporal clustering of these data identified proteins associated with inflammation, cartilage formation and bone remodeling stages of healing. VEGF, Wnt, and TGF-ßsignaling pathways were restricted to the period of cartilage formation. Comparison of the proteomic and transcriptomic profiles showed that 87.5% of proteins in serum had concordant expression to their mRNA expression in the callus, while 12.5% of the protein and mRNA expression patterns were discordant. The discordant proteins that were elevated in the serum but down regulated in callus mRNA expression were related to clotting functions, allograft rejection, and complement function. While proteins down regulated in the serum and elevated in callus mRNA were associated with osteoblast function, NF-ĸb, and activin signaling. These data show the serum proteome may be used to monitor the different biological stages of fracture healing and have translational potential in assessing human fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1153-1163, 2018.