Body Mass Index Is Associated With Myocutaneous Free Flap Reliability: Overcoming the Obesity Obstacle With a Proposed Clinical Algorithm to Identify and Manage High-Risk Patients Undergoing Gracilis Free Flap With Skin Paddle Harvest.

INTRODUCTION: The purpose of this study was to evaluate the role of body mass index (BMI) in predicting postoperative complications following myocutaneous free flap transfer. In addition, we sought to identify certain body composition variables that may be used to stratify patients into low- versus high-risk for gracilis myocutaneous free flap with skin paddle failure. METHODS: Using the National Surgical Quality Improvement Program database, we collected data for all patients who underwent myocutaneous free flap transfer from 2015 to 2021. Demographic data, medical history, surgical characteristics, and postoperative outcomes, including complications, reoperations, and readmissions, were collected. Body mass index was correlated with outcome measures to determine its role in predicting myocutaneous free flap reliability. Subsequently, we retrospectively obtained measurements of perigracilis anatomy in patients who underwent computed tomography angiography bilateral lower extremity scans with intravenous contrast at our institution. We compared body composition data with mathematical equations calculating the potential area along the skin of the thigh within which the gracilis perforator may be found. RESULTS: Across the United States, 1549 patients underwent myocutaneous free flap transfer over the 7-year study period. Being in obesity class III (BMI ≥40 kg/m2) was associated with a 4-times greater risk of flap complications necessitating a return to the operating room compared with being within the normal BMI range. In our computed tomography angiography analysis, average perigracilis adipose thickness was 18.3 ± 8.0 mm. Adipose thickness had a strong, positive exponential relationship with the area of skin within which the perforator may be found. CONCLUSIONS: In our study, higher BMI was associated with decreased myocutaneous free flap reliability. Specifically, inner thigh adipose thickness can be used to estimate the area along the skin within which the gracilis perforator may be found. This variable, along with BMI, can be used to identify patients who are considered high-risk for flap failure and who may benefit from additional postoperative monitoring, such as the use of a color flow Doppler probe and more frequent and prolonged skin paddle monitoring.

Evaluation of instrumentation and pedicle screw design for posterior lumbar fixation: A pre-clinical in vivo/ex vivo ovine model.

Background: Stabilization procedures of the lumbar spine are routinely performed for various conditions, such as spondylolisthesis and scoliosis. Spine surgery has become even more common, with the incidence rates increasing ~30% between 2004 and 2015. Various solutions to increase the success of lumbar stabilization procedures have been proposed, ranging from the device's geometrical configuration to bone quality enhancement via grafting and, recently, through modified drilling instrumentation. Conventional (manual) instrumentation renders the excavated bony fragments ineffective, whereas the "additive" osseodensification rotary drilling compacts the bone fragments into the osteotomy walls, creating nucleating sites for regeneration. Methods: This study aimed to compare both manual versus rotary Osseodensification (OD) instrumentation as well as two different pedicle screw thread designs in a controlled split animal model in posterior lumbar stabilization to determine the feasibility and potential advantages of each variable with respect to mechanical stability and histomorphology. A total of 164 single thread (82 per thread configuration), pedicle screws (4.5 × 35 mm) were used for the study. Each animal received eight pedicles (four per thread design) screws, which were placed in the lumbar spine of 21 adult sheep. One side of the lumbar spine underwent rotary osseodensification instrumentation, while the contralateral underwent conventional, hand, instrumentation. The animals were euthanized after 6- and 24-weeks of healing, and the vertebrae were removed for biomechanical and histomorphometric analyses. Pullout strength and histologic analysis were performed on all harvested samples. Results: The rotary instrumentation yielded statistically (p = 0.026) greater pullout strength (1060.6 N ± 181) relative to hand instrumentation (769.3 N ± 181) at the 24-week healing time point. Histomorphometric analysis exhibited significantly higher degrees of bone to implant contact for the rotary instrumentation only at the early healing time point (6 weeks), whereas bone area fraction occupancy was statistically higher for rotary instrumentation at both healing times. The levels of soft tissue infiltration were lower for pedicle screws placed in osteotomies prepared using OD instrumentation relative to hand instrumentation, independent of healing time. Conclusion: The rotary instrumentation yielded enhanced mechanical and histologic results relative to the conventional hand instrumentation in this lumbar spine stabilization model.

Degree of Soft Tissue Injury is a Major Determinant of Successful Arterial Repair in the Extremity: A New Classification of Extremity Arterial Injury?

BACKGROUND: This study aimed to investigate outcomes after extremity arterial injury repair and examined the association between outcomes and the degree of soft tissue injury and vascular repair methods. METHODS: A retrospective study was conducted on 106 patients (108 cases) who underwent emergent microsurgical repair of extremity arterial injury due to trauma and non-perfusion of the affected extremity. The cases were divided into three groups by degree of associated soft tissue injuries: (A) adequate soft tissue coverage over the injured major vessels after radical debridement, (B) inadequate soft tissue coverage over the injured major vessels after radical debridement, and (C) radical debridement was not feasible due to unclear extent of injured soft tissue. Differences in vascular repair methods and outcomes among the three groups were analyzed. RESULTS: In Group A (n = 61), microvascular suture and vessel graft achieved 95.1% and 85.0% successful limb reperfusion, respectively. In Group B (n = 31), vessel reconstruction with flap coverage achieved 100% successful reperfusion. Vessel graft achieved 28.6% successful limb reperfusion, while there were no cases of successful reperfusion using microvascular sutures. In Group C (n = 16), no vascular repair method achieved successful reperfusion. There were significant differences among the three groups in successful reperfusion (p < 0.001) and limb salvage (p < 0.001). CONCLUSION: The extent of associated soft tissue injury was associated with different vascular repair methods and outcomes. We propose a new system for classifying these injuries according to the degree of associated soft tissue injury.

Physiochemical and bactericidal activity evaluation: Silver-augmented 3D-printed scaffolds-An in vitro study.

HYPOTHESIS: Injuries requiring resection of tissue followed by autogenous bone transfer may be prone to infection by Staphylococcus aureus, impeding recovery and increasing medical costs. For critical sized defects, the common approach to reconstruction is a tissue transfer procedure but is subject to limitations (e.g., donor site morbidity, cost, operating time). Utilizing beta tricalcium phosphate (ß-TCP) as bone grafting material augmented with silver (Ag), a custom graft may be 3D printed to overcome limitations and minimize potential infections. EXPERIMENTS: Scaffolds were 3D printed and augmented with Ag by external attack on the surface by silver nitrate (AgNO3 ) at varying concentrations (0.1, 1.0, 10% wt/wt of scaffold). The augmented scaffolds were evaluated utilizing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectroscopy (ICP-MS) to verify the presence of Ag and phosphate (PO4 ) groups followed by electron microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to gather information of chemical and physical properties. Preliminary biocompatibility and bactericidal capacity of the scaffolds were tested using human osteoprogenitor (hOP) cells and methicillin-sensitive S. aureus strain, respectively. RESULTS: XRD, FTIR, ICP-MS, TGA, and DSC confirmed presence of Ag and PO4 groups, whereas electron microscopy showed a decrease in Ca and an increase in Ag ions, decreasing Ca/P ratio with increasing surfactant concentrations. PrestoBlue assays yielded an increase in fluorescence cell counts among experimental groups with lower concentrations of Ag characterized by their characteristic trapezoidal shape whereas cytotoxicity was observed at higher concentrations. Similar observations were made with alkaline phosphatase assays. Antimicrobial evaluation showed reduced colony-forming units (CFU) among all experimental groups when compared to 100% ß-TCP. ß-TCP scaffolds augmented with Ag ions facilitate antibacterial effects while promoting osteoblast adhesion and proliferation.

Perforator Detection by Thermographic Imaging Augmented With Tourniquet-Reperfusion: A Modified Approach and Preliminary Report in Distal Lower Leg Reconstruction.

BACKGROUND: Dynamic infrared thermography provides a new imaging method of perforator detection. This study introduces an augmented technique to improve its accuracy by tourniquet-reperfusion and reports its preliminary use in the distal lower leg reconstruction. METHODS: A tourniquet (450 mm Hg) was applied for 3 minutes on proximal thighs. After the tourniquet release, the rewarming rate and pattern of hotspots were observed by thermography to delineate the location and quality of perforators. The results were compared with those detected by computed tomographic angiography. Clinically, the local transferred posterior tibial artery or peroneal artery propeller perforator flap was performed in 9 patients for the distal lower leg reconstruction. RESULTS: There was a 20- to 140-second "perforator observing window" after the tourniquet release. Tourniquet-reperfusion augmented thermal imaging method (TRATIM) had a sensitivity of 90.3% and a positive predictive value of 93.3%. The TRATIM and computed tomographic angiography had an excellent concordance with a kappa index value of 0.839 (P < 0.001). Based on the TRATIM, 9 propeller perforator flaps were successfully designed and raised for the distal lower leg resurfacing. All flaps survived entirely, except one with size of 1.0 cm × 2.0 cm that had terminal necrosis. CONCLUSIONS: The TRATIM is a quick, easy, cheap, and reliable approach for perforator detection in the lower leg. With the aid of TRATIM, a customized propeller perforator flap could be raised efficiently for the distal lower leg reconstruction.

Osseodensification drilling vs conventional manual instrumentation technique for posterior lumbar fixation: Ex-vivo mechanical and histomorphological analysis in an ovine model.

Lumbar fusion is a procedure associated with several indications, but screw failure remains a major complication, with an incidence ranging 10% to 50%. Several solutions have been proposed, ranging from more efficient screw geometry to enhance bone quality, conversely, drilling instrumentation have not been thoroughly explored. The conventional instrumentation (regular [R]) techniques render the bony spicules excavated impractical, while additive techniques (osseodensification [OD]) compact them against the osteotomy walls and predispose them as nucleating surfaces/sites for new bone. This work presents a case-controlled split model for in vivo/ex vivo comparison of R vs OD osteotomy instrumentation in posterior lumbar fixation in an ovine model to determine feasibility and potential advantages of the OD drilling technique in terms of mechanical and histomorphology outcomes. Eight pedicle screws measuring 4.5 mm × 45 mm were installed in each lumbar spine of eight adult sheep (four per side). The left side underwent R instrumentation, while the right underwent OD drilling. The animals were killed at 6- and 12-week and the vertebrae removed. Pullout strength and non-decalcified histologic analysis were performed. Significant mechanical stability differences were observed between OD and R groups at 6- (387 N vs 292 N) and 12-week (312 N vs 212 N) time points. Morphometric analysis did not detect significant differences in bone area fraction occupancy between R and OD groups, while it is to note that OD showed increased presence of bone spiculae. Mechanical pullout testing demonstrated that OD drilling provided higher degrees of implant anchoring as a function of time, whereas a significant reduction was observed for the R group.

Cross limb vessel transfer for salvage of the extremity with irreparable artery injury.

PURPOSE: Complex injuries of the extremity can be very challenging to treat. In the setting of soft tissue infection and vascular defect, arterial reconstructions are at high risk of failure. Historically, there have not been good options to successfully salvage limbs with these serious injuries. We describe our experience of utilizing a cross limb vessel transfer to salvage the limb. METHODS: Patients were identified retrospectively with complex vascular injuries of the extremity and wound infection, who were treated with a cross limb vessel transfer. Once the infection has successfully been cleared, flow-through flap transfer was performed for definitive reconstruction of the arterial injury. Data collated included patient demographics, injury and operation details, and post-operative outcomes including blood supply of the limb, wound infection and complications. RESULTS: Between April 2014 and January 2017, 3 patients with an average age of 21 years (range, 16-29) were admitted. The median length of hospital stay was 62 days (range, 26-122). The average number of operation was 7.3 times (range, 6-10). Two patients' upper limb had survived with limited movement, relatively minor donor site morbidity and confirmed flow through the vessel reconstruction using CTA, while one patient had lower limb amputation due to severe infection and prolonged ischemia time. CONCLUSIONS: This series of patients demonstrates that cross limb vessel transfer is an invaluable technique to salvage the limb in patients with complex vascular injury and wound infection. However, for lower limb with prolonged ischemia time and severe infection, limb salvage is not recommended.