Outcome of rectus femoris muscle flaps performed by vascular surgeons for the management of complex groin wounds after femoral artery reconstructions.

OBJECTIVE: Groin wound complications after femoral artery reconstructions are highly morbid and notoriously difficult to treat. Successful techniques include long-term antibiotic therapy, operative débridement, and muscle flap coverage. Historically, more complex muscle flap coverage, such as a rectus femoris muscle flap (RFF), has been performed by plastic and reconstructive surgeons. In this study, the experience of vascular surgeons performing RFF in the management of wound complications after femoral artery reconstructions is reported. METHODS: Clinical data between 2012 and 2018 were retrospectively analyzed. Data were summarized, and standard statistical analysis was performed. RESULTS: There were 23 patients who underwent 24 RFFs for coverage of complex groin wounds after femoral artery reconstructions. One of the 23 patients underwent bilateral RFFs. In this study cohort, patients had a median age of 67.5 years, and 79% (n = 19) were male. Median body mass index was 28.0 kg/m2, and 38% of patients were classified as obese on the basis of body mass index criteria. A history of tobacco use was present in 88%; however, only 29% were current smokers. Diabetes was present in 38% of patients and chronic kidney disease in 29%. Of the 24 RFFs, 14 (58%) were constructed in patients with reoperative groin surgery resulting in the need for muscle flap coverage. Femoral endarterectomy was the most common index procedure (46%), followed by infrainguinal leg bypass surgery (17%) and aortobifemoral bypass (17%). Grafts used during the original reconstruction included 12 bovine pericardial patches (50%), 6 Dacron grafts (25%), 4 PTFE grafts (17%), and 2 autogenous reconstructions (8%). Microbiology data identified 33% of patients (n = 8) to have gram-positive bacterial infections alone, 21% (n = 5) to have gram-negative infections alone, and 29% (n = 7) to have polymicrobial infections; 4 patients (13%) had negative intraoperative culture data. Median hospital stay after RFF was 8 days, and median follow-up time was 29.3 months. Major amputation was avoided in 20 of 24 limbs (83%) undergoing RFF. Eight patients underwent intentional graft or patch explantation (33%) before RFF, whereas 14 of the remaining 15 patients (93%) had successful salvage of the graft or patch after RFF. Two of the patients (13%) who underwent RFF with the intention of salvaging a prosthetic graft or patch required later graft excision. After RFF, 30-day and 1-year survival was 96% and 87%, respectively. CONCLUSIONS: RFF coverage of complex groin wounds after femoral artery reconstructions may safely be performed by vascular surgeons with excellent outcomes.

Age-related differences in the morphology of microdamage propagation in trabecular bone.

Microdamage density has been shown to increase with age in trabecular bone and is associated with decreased fracture toughness. Numerous studies of crack propagation in cortical bone have been conducted, but data in trabecular bone is lacking. In this study, propagation of severe, linear, and diffuse damage was examined in trabecular bone cores from the femoral head of younger (61.3±3.1 years) and older (75.0±3.9 years) men and women. Using a two-step mechanical testing protocol, damage was first initiated with static uniaxial compression to 0.8% strain then propagated at a normalized stress level of 0.005 to a strain endpoint of 0.8%. Coupling mechanical testing with a dual-fluorescent staining technique, the number and length/area of propagating cracks were quantified. It was found that the number of cycles to the test endpoint was substantially decreased in older compared to younger samples (younger: 77,372±15,984 cycles; older: 34,944±11,964 cycles, p=0.06). This corresponded with a greater number of severely damaged trabeculae expanding in area during the fatigue test in the older group. In the younger group, diffusely damaged trabeculae had a greater damage area, which illustrates an efficient energy dissipation mechanism. These results suggest that age-related differences in fatigue life of human trabecular bone may be due to differences in propagated microdamage morphology.

Age-related changes in human trabecular bone: Relationship between microstructural stress and strain and damage morphology.

Accumulation of microdamage in aging and disease can cause skeletal fragility and is one of several factors contributing to osteoporotic fractures. To better understand the role of microdamage in fragility fracture, the mechanisms of bone failure must be elucidated on a tissue-level scale where interactions between bone matrix properties, the local biomechanical environment, and bone architecture are concurrently examined for their contributions to microdamage formation. A technique combining histological damage assessment of individual trabeculae with linear finite element solutions of trabecular von Mises and principal stress and strain was used to compare the damage initiation threshold between pre-menopausal (32-37 years, n=3 donors) and post-menopausal (71-80 years, n=3 donors) femoral cadaveric bone. Strong associations between damage morphology and stress and strain parameters were observed in both groups, and an age-related decrease in undamaged trabecular von Mises stress was detected. In trabeculae from younger donors, the 95% CI for von Mises stress on undamaged regions ranged from 50.7-67.9MPa, whereas in trabeculae from older donors, stresses were significantly lower (38.7-50.2, p<0.01). Local microarchitectural analysis indicated that thinner, rod-like trabeculae oriented along the loading axis are more susceptible to severe microdamage formation in older individuals, while only rod-like architecture was associated with severe damage in younger individuals. This study therefore provides insight into how damage initiation and morphology relate to local trabecular microstructure and the associated stresses and strains under loading. Furthermore, by comparison of samples from pre- and post-menopausal women, the results suggest that trabeculae from younger individuals can sustain higher stresses prior to microdamage initiation.