Flexor Tendon Repair in Zone II Augmented With an Externalized Detensioning Suture: Protected Flexor Tendon Repair.

Flexor tendon repair in zone II benefits from early finger motion to prevent stiffness. This article presents a technique that serves to augment a zone II flexor tendon repair with an externalized detensioning suture that can be used following any commonly employed repair method. This simple technique enables early active motion and is suited for patients who are less likely to be compliant after surgery or when the soft-tissue injury to the finger and hand is substantial. Although this technique substantially strengthens the repair, a possible drawback is that the tendon excursion distal to the repair is limited until the externalized suture is removed, which may lead to less motion of the distal interphalangeal than what may have occurred without the detensioning suture.

Composite Tissue Preservation.

Composite tissue (CT) preservation is important to outcomes after replant or transplant. Since the first limb replant, the mainstay of preservation has been static cold storage with the amputated part being placed in moistened gauze over ice. Historically, the gold-standard in solid organ preservation has been static cold storage with specialized solution, but this has recently evolved in the last few decades to develop technologies such as machine perfusion and even persufflation. This review explores the impact of cooling and oxygenation on CT, summarizes the work done in the area of CT preservation, discusses lessons learned from our experience in solid organ preservation, and proposes future directions.

Characterization of Adipose Tissue Product Quality Using Measurements of Oxygen Consumption Rate.

BACKGROUND: Fat grafting is a common procedure in plastic surgery but associated with unpredictable graft retention. Adipose tissue (AT) "product" quality is affected by the methods used for harvest, processing and transfer, which vary widely amongst surgeons. Currently, there is no method available to accurately assess the quality of AT. OBJECTIVES: In this study, we present a novel method for the assessment of AT product quality through direct measurements of oxygen consumption rate (OCR). OCR has exhibited potential in predicting outcomes following pancreatic islet transplant. Our study aim was to reapportion existing technology for its use with AT preparations and to confirm that these measurements are feasible. METHODS: OCR was successfully measured for en bloc and postprocessed AT using a stirred microchamber system. OCR was then normalized to DNA content (OCR/DNA), which represents the AT product quality. RESULTS: Mean (±SE) OCR/DNA values for fresh en bloc and post-processed AT were 149.8 (± 9.1) and 61.1 (± 6.1) nmol/min/mg DNA, respectively. These preliminary data suggest that: (1) OCR and OCR/DNA measurements of AT harvested using conventional protocol are feasible; and (2) standard AT processing results in a decrease in overall AT product quality. CONCLUSIONS: OCR measurements of AT using existing technology can be done and enables accurate, real-time, quantitative assessment of the quality of AT product prior to transfer. The availability and further validation of this type of assay could enable optimization of fat grafting protocol by providing a tool for the more detailed study of procedural variables that affect AT product quality.

Characterization of adipose tissue for autologous fat grafting.

Fat grafting is a common procedure in aesthetic and reconstructive plastic surgery, but variable graft retention limits its utility. Unpredictable clinical outcomes with fat grafting can be explained in part by the lack of standardized protocols for harvesting, processing, and transplanting adipose tissue (AT). Historically, plastic surgeons have relied on trial and error and their clinical experience to develop fat grafting protocols. Optimization of fat grafting protocols requires systematic assessment of the impact that key variables have on the quality of the AT preparation at each step of the procedure. In this article, we review recent findings regarding the composition and quality of AT prepared for fat grafting and the strengths and limitations of existing AT characterization assays. We discuss the need for an assessment of the viability of intact AT (ie, conventionally harvested AT that has not been disrupted further) by means of an operator-independent, quantitative assay that can be performed in real time and generates reproducible data. Promising assays for the characterization of cell product quality have been developed for other therapeutic applications, such as transplantation of pancreatic islet cells. The development or adaptation of a gold-standard assay to determine the quality of an AT preparation may help to standardize fat grafting protocols and improve clinical outcomes.

Temperature profiles of different cooling methods in porcine pancreas procurement.

Porcine islet xenotransplantation is a promising alternative to human islet allotransplantation. Porcine pancreas cooling needs to be optimized to reduce the warm ischemia time (WIT) following donation after cardiac death, which is associated with poorer islet isolation outcomes. This study examines the effect of four different cooling Methods on core porcine pancreas temperature (n = 24) and histopathology (n = 16). All Methods involved surface cooling with crushed ice and chilled irrigation. Method A, which is the standard for porcine pancreas procurement, used only surface cooling. Method B involved an intravascular flush with cold solution through the pancreas arterial system. Method C involved an intraductal infusion with cold solution through the major pancreatic duct, and Method D combined all three cooling Methods. Surface cooling alone (Method A) gradually decreased core pancreas temperature to <10 °C after 30 min. Using an intravascular flush (Method B) improved cooling during the entire duration of procurement, but incorporating an intraductal infusion (Method C) rapidly reduced core temperature 15-20 °C within the first 2 min of cooling. Combining all methods (Method D) was the most effective at rapidly reducing temperature and providing sustained cooling throughout the duration of procurement, although the recorded WIT was not different between Methods (P = 0.36). Histological scores were different between the cooling Methods (P = 0.02) and the worst with Method A. There were differences in histological scores between Methods A and C (P = 0.02) and Methods A and D (P = 0.02), but not between Methods C and D (P = 0.95), which may highlight the importance of early cooling using an intraductal infusion. In conclusion, surface cooling alone cannot rapidly cool large (porcine or human) pancreata. Additional cooling with an intravascular flush and intraductal infusion results in improved core porcine pancreas temperature profiles during procurement and histopathology scores. These data may also have implications on human pancreas procurement as use of an intraductal infusion is not common practice.

Silicone rubber membrane devices permit islet culture at high density without adverse effects.

Introduction: Conventional culture conditions, such as in T-flasks, require that oxygen diffuse through the medium to reach the islets; in turn, islet surface area density is limited by oxygen availability. To culture a typical clinical islet preparation may require more than 20 T-175 flasks at the standard surface area density of 200 IE/cm2. To circumvent this logistical constraint, we tested islets cultured on top of silicon gas-permeable (GP) membranes which place islets in close proximity to ambient oxygen. Methods: Oxygenation of individual islets under three culture conditions, standard low-density, non-GP high density, and GP high density, were first modeled with finite element simulations. Porcine islets from 30 preparations were cultured for 2 days in devices with GP membrane bottoms or in paired cultures under conventional conditions. Islets were seeded at high density (HD, ∼4000 IE/cm2, as measured by DNA) in both GP and non-GP devices. Results: In simulations, individual islets under standard culture conditions and high density cultures on GP membranes were both well oxygenated whereas non-GP high density cultured islets were anoxic. Similarly, compared to the non-GP paired controls, islet viability and recovery were significantly increased in HD GP cultures. The diabetes reversal rate in nude diabetic mice was similar for HD GP devices and standard cultures but was minimal with non-GP HD cultures. Discussion: Culturing islets in GP devices allows for a 20-fold increase of islet surface area density, greatly simplifying the culture process while maintaining islet viability and metabolism.

Antihypertensive pharmacotherapy and long-term outcomes in pediatric kidney transplantation.

Hypertension (HTN) is common in pediatric recipients following kidney transplantation (KT). We retrospectively assessed the impact of HTN on long-term (>10-yr) outcomes in pediatric KT recipients (aged < 18 yr) at our center. Two hundred and ninety-three pediatric KT recipients (83% living donor [LD]) with graft survival (GS) for ≥5 yr were studied. HTN was defined by antihypertensive medication use at five yr post-KT. One hundred and sixty (55%) recipients did not have HTN, and 133 (45%) had HTN at five yr post-KT. There were no differences in actuarial patient survival between cohorts. Actuarial GS at 15 and 20 yr was 68% and 53% for recipients without HTN, and 53% and 33% for recipients with HTN (p = 0.006). Among LD recipients using one antihypertensive, GS at 15 yr was 100% for those using an angiotensin-converting enzyme inhibitor (ACEI) and 44% for those not using an ACEI (p = 0.04). Among these recipients, HTN treated with no ACEI was a significant risk factor for graft failure at >5 yr (hazard ratio [HR] = 2.5, p = 0.02), but HTN treated with an ACEI was not (HR = 0.6, p = 0.7). HTN at five yr post-KT is associated with poorer long-term GS in pediatric recipients, but ACEI therapy may enable better outcomes and should be studied further.

Radiographic Thumb Metacarpal Subsidence Following Ligament Reconstruction With Tendon Interposition and Suture-Only Suspension Arthroplasty in the Treatment of Basal Joint Arthritis.

BACKGROUND: The thumb carpometacarpal (CMC) joint is a common source of osteoarthritis. Following trapeziectomy, ligament reconstruction with tendon interposition (LRTI) is considered a "gold standard" treatment, but suture-only suspension arthroplasty (SSA) has recently emerged as a simpler alternative. Currently, there is no objective radiographic study comparing subsidence following these 2 techniques. METHODS: This study is a retrospective review of 23 patients (10 LRTI, 13 SSA) that had at least 6 months of radiographic follow-up following thumb CMC arthroplasty. Posteroanterior radiographs at a preoperative timepoint, and at the 2-week and greater than 6-month postoperative timepoints were evaluated for actual trapezial height, as well as trapezial height normalized to capitate, thumb metacarpal, and proximal phalangeal heights. Normalized trapezial heights were calculated, and preoperative values were compared with greater than 6-month postoperative values. In addition, actual and normalized trapezial heights following LRTI and SSA were compared at each timepoint. RESULTS: Mean trapezial height decreased from approximately 12 to 5 mm (reduction of ~60%, P < .05) in both groups with no differences when comparing LRTI and SSA at each timepoint. All normalized trapezial heights revealed differences from preoperative to greater than 6-month postoperative timepoints, but no differences between LRTI and SSA. CONCLUSIONS: Ligament reconstruction with tendon interposition and SSA exhibit equivalent actual and normalized trapezial heights over a greater than 6-month postoperative time course.

Prospective Cohort Study Comparing Ligament Reconstruction with Tendon Interposition and Suture-Only Suspension Arthroplasty.

BACKGROUND: Basal joint arthritis is a common form of osteoarthritis. There is no consensus procedure for maintenance of trapezial height following trapeziectomy. Suture-only suspension arthroplasty (SSA) is a simple method for stabilizing the thumb metacarpal following trapeziectomy. METHODS: This single-institution, prospective, cohort study compares trapeziectomy followed by either ligament reconstruction with tendon interposition (LRTI) or SSA for the treatment of basal joint arthritis. Patients underwent LRTI or SSA from May of 2018 to December of 2019. Visual analogue scale pain scores; Disabilities of the Arm, Shoulder and Hand questionnaire functional scores; clinical thumb range of motion, pinch, and grip strength data; and patient-reported outcomes were recorded and analyzed preoperatively and at 6 weeks and 6 months postoperatively. RESULTS: Total number of study participants was 45 (LRTI, n = 26; SSA, n = 19). Mean ± SE age was 62.4 ± 1.5 years; 71% were female patients; and 51% underwent surgery on the dominant side. Visual analogue scale scores improved for LRTI and SSA ( P < 0.0001) over 6 months, with no differences between groups at any time point ( P > 0.3). Disabilities of the Arm, Shoulder and Hand questionnaire scores improved for LRTI and SSA over 6 months ( P < 0.0001), with no differences between groups at any time point ( P > 0.3). Following SSA, opposition improved ( P = 0.02), but not as well for LRTI ( P = 0.16). Grip and pinch strength decreased following LRTI and SSA at 6 weeks but recovered similarly for both groups over 6 months. Patient-reported outcomes were generally no different between groups at all time points. CONCLUSION: LRTI and SSA are similar procedures following trapeziectomy relative to pain, function, and strength recovery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Hypoxia within subcutaneously implanted macroencapsulation devices limits the viability and functionality of densely loaded islets.

Introduction: Subcutaneous macroencapsulation devices circumvent disadvantages of intraportal islet therapy. However, a curative dose of islets within reasonably sized devices requires dense cell packing. We measured internal PO2 of implanted devices, mathematically modeled oxygen availability within devices and tested the predictions with implanted devices containing densely packed human islets. Methods: Partial pressure of oxygen (PO2) within implanted empty devices was measured by noninvasive 19F-MRS. A mathematical model was constructed, predicting internal PO2, viability and functionality of densely packed islets as a function of external PO2. Finally, viability was measured by oxygen consumption rate (OCR) in day 7 explants loaded at various islet densities. Results: In empty devices, PO2 was 12 mmHg or lower, despite successful external vascularization. Devices loaded with human islets implanted for 7 days, then explanted and assessed by OCR confirmed trends proffered by the model but viability was substantially lower than predicted. Co-localization of insulin and caspase-3 immunostaining suggested that apoptosis contributed to loss of beta cells. Discussion: Measured PO2 within empty devices declined during the first few days post-transplant then modestly increased with neovascularization around the device. Viability of islets is inversely related to islet density within devices.

Energetic recovery in porcine grafts by minimally invasive liver oxygenation.

BACKGROUND: Gaseous insufflation of oxygen via the venous vascular system has proven to be an effective tool for preventing anoxic tissue injury after extended time periods of ischemic liver preservation. Most experimental studies so far have been undertaken in rat models and include a series of pinpricks into postsinusoidal venules as an outlet for the insufflated gas. Here, we describe a simplified technique for minimally invasive liver oxygenation in porcine grafts, representing a hassle-free access to organ oxygenation without vascular lesions. METHODS: We retrieved livers from Landrace pigs and cold-stored them in histidine-tryptophan-ketoglutarate solution. Subsequent to 18 h preservation, we treated some livers for an additional 2 h with gaseous oxygen, insufflated via silicone tubing inserted into the suprahepatic caval vein. Gas pressure was limited to 18 mm Hg. We occluded the infrahepatic caval vein with a bulldog clamp. Gas bubbles left the graft via the portal vein. We assessed liver integrity by energetic tissue status and by controlled in vitro reperfusion with autologous blood. RESULTS: Magnetic resonance imaging demonstrated homogeneous gas distribution in the persufflated tissue without major shunting. Biochemical analyses revealed effective and homogeneous restoration of energetic homeostasis in the ischemic graft before reperfusion. Sinusoidal endothelial clearance of hyaluronic acid was significantly improved upon reperfusion, as was hepatic arterial flow. Parenchymal enzyme loss was concordantly mitigated after minimally invasive liver oxygenation. CONCLUSIONS: Our results indicate that gaseous oxygen persufflation of the porcine liver is possible without tissue trauma, and significantly enhances post-preservation recovery of the graft.

Outcome of living kidney donors left with multiple renal arteries.

Individuals with kidneys having ≥ 2 arteries appear to have an increased incidence of hypertension. Whether kidney donors in whom the remaining kidney has ≥ 2 arteries are at increased risk of hypertension is unknown. Therefore, we studied 3685 kidney donors to determine whether donors left with a kidney having ≥ 2 arteries were at increased risk of hypertension, impaired renal function, or death. Cohorts were assigned based on our practice pattern and the anatomy of the donated kidney. Of the 3685 donors, 1211 were estimated to have a remaining kidney with ≥ 2 arteries. Mean follow-up time for the single-artery group was 14.1 (± 11.0) yr and 15.3 (± 11.2) yr for the ≥ 2 artery group. Six-month hospital readmission rate was 1.4% and 1.2%, hypertension was noted in 22.4% and 21.8% and proteinuria in 9.7% and 9.6%, and estimated glomerular filtration rate at last follow-up was 62 (± 28) and 62 (± 16) for single vs. ≥ 2 renal artery groups, respectively. Our data suggest no adverse clinical sequelae nor any decrease in long-term survival for donors left with a kidney having ≥ 2 renal arteries.

Persufflation (or gaseous oxygen perfusion) as a method of organ preservation.

Improved preservation techniques have the potential to improve transplant outcomes by better maintaining donor organ quality and by making more organs available for allotransplantation. Persufflation, (PSF, gaseous oxygen perfusion) is potentially one such technique that has been studied for over a century in a variety of tissues, but has yet to gain wide acceptance for a number of reasons. A principal barrier is the perception that ex vivo PSF will cause in vivo embolization post-transplant. This review summarizes the extensive published work on heart, liver, kidney, small intestine and pancreas PSF, discusses the differences between anterograde and retrograde PSF, and between PSF and other conventional methods of organ preservation (static cold storage, hypothermic machine perfusion). Prospective implications of PSF within the broader field of organ transplantation, and in the specific application with pancreatic islet isolation and transplant are also discussed. Finally, key issues that need to be addressed before PSF becomes a more widely utilized preservation strategy are summarized and discussed.

Flap Monitoring Using Transcutaneous Oxygen or Carbon Dioxide Measurements.

Free tissue transfer is a cornerstone of complex reconstruction. In many cases, it represents the last option available for a patient and their reconstruction. At high-volume centers, the risk of free flap failure is low but its occurrence can be devastating. Currently, the mainstay for flap monitoring is the clinical examination. Though reliable when performed by experienced clinicians, the flap exam is largely subjective, is performed discontinuously, and often results in significant time delay between detection of flap compromise and intervention. Among emerging flap monitoring technologies, the most promising appear to be those that rely on noninvasive transcutaneous oxygen and carbon dioxide measurements, which provide information regarding flap perfusion. In this article, we review and summarize the literature on various techniques but primarily emphasizing those technologies that rely on transcutaneous gas measurements. We also define characteristics for the ideal flap monitoring tool and discuss critical barriers, predominantly cost, preventing more widespread utilization of adjunct monitoring technologies, and their implications.

Paramagnetic microparticles do not elicit islet cytotoxicity with co-culture or host immune reactivity after implantation.

BACKGROUND: Paramagnetic microparticles (MPs) may be useful in pancreatic islet purification, in particular purification of porcine islets as a potential xenotransplantation product. We assessed whether MPs affect islet function or induce an adverse effect following implantation. METHODS: Porcine islets were co-cultured with 0, 500, and 1500 MPs per islet equivalent (IE) for 1 day and with 0 and 1500 MPs/IE for 7 days. Fractional viability was assessed using oxygen consumption rate normalized to DNA content (OCR/DNA) and after 7-day co-culture by perifusion glucose-stimulated insulin secretion (GSIS) and by transplantation under the renal capsule of diabetic nude mice. To assess an inflammatory response or immune reaction, MPs (∼10(7)) were implanted under the renal capsule of C57BL/6 mice. RESULTS: No statistically significant differences were measured in OCR/DNA (mean ± SE) following 1-day co-culture with 0, 500, or 1500 MPs/IE (243.3 ± 4.5, 211.3 ± 8.1, or 230.6 ± 11.3 nmol/min·mgDNA, respectively) or following 7-day co-culture with 0 or 1500 MPs/IE (248.5 ± 1.4 or 252.9 ± 4.7 nmol/min·mgDNA, respectively). GSIS was not affected by the presence of MPs; first- and second-phase insulin area-under-the-curve (mean ± SE) reflected no statistically significant differences after 7-day co-culture between 0 and 1500 MPs/IE (8.36 ± 0.29 and 8.45 ± 0.70 pg/ml·min·ngDNA for first-phase; 69.73 ± 2.18 and 65.70 ± 4.34 pg/ml·min·ngDNA for second-phase, respectively). Islets co-cultured with MPs normalized hyperglycemia in diabetic nude mice, suggesting no adverse effects on in vivo islet function. Implantation of MPs did not elicit tissue injury, inflammatory change or immune reactivity. CONCLUSION: MPs do not adversely affect islet viability or function during co-culture, and MPs are not immune reactive following implantation.

Consecutive Bilateral Breast Reconstruction Using Stacked Abdominally Based and Posterior Thigh Free Flaps.

BACKGROUND: Multiple perforator flap breast reconstruction is an option that avoids implants in selected patients with minimal donor tissue. The technique addresses the need for additional skin to help create a breast envelope with more natural ptosis and additional volume to help create a body-appropriate breast mound while avoiding serial fat grafting. Using four flaps for the reconstruction of two breasts (bilateral stacked flap reconstruction) has recently become feasible with the advancement of microsurgical techniques, increased experience with alternative perforator flaps, and use of co-surgery. In this article, we describe our early experience with bilateral stacked flap breast reconstruction. METHODS: From January of 2014 to October of 2018, the senior co-surgeons performed 50 consecutive bilateral stacked flap operations at a single institution. All reconstructions were performed in delayed fashion with a mean operative time of 10 hours. Most breasts (94 percent) were reconstructed with a deep inferior epigastric perforator flap combined with a profunda artery perforator flap. Most flap microanastomoses (91.5 percent) were performed directly with internal mammary vessels. The larger of the two flaps was typically placed inferiorly (66 percent), but there was significant inset variability. RESULTS: Of 200 flaps, five were lost (2.5 percent). Seven take-backs were needed for a flap-related concern, which included two negative explorations and a flap salvage. The most common non-flap-related complication was a thigh wound (17 total, eight requiring a procedure). CONCLUSION: The authors' early experience suggests that bilateral stacked flap breast reconstruction is a powerful tool that can be performed with an acceptable microsurgical risk and an acceptable complication profile in highly selected patients. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Three-dimensional (3D) synthetic printing for the manufacture of non-biodegradable models, tools and implants used in surgery: a review of current methods.

The advent of three-dimensional (3D) printing in the 1980s ushered in a new era of manufacturing. Original 3D printers were large, expensive and difficult to operate, but recent advances in 3D printer technologies have drastically increased the accessibility of these machines such that individual surgical departments can now afford their own 3D printers. As adoption of 3D printing technology has increased within the medical industry so too has the number of 3D printable materials. Selection of the appropriate printer and material for a given application can be a daunting task for any clinician. This review seeks to describe the benefits and drawbacks of different 3D printing technologies and the materials used therein. Commercially available printers using fused deposition modelling or fused filament fabrication technology and relatively inexpensive thermoplastic materials have enabled rapid manufacture of anatomic models and intraoperative tools as well as implant prototyping. Titanium alloys remain the gold-standard material for various implants used in the fixation of craniofacial or extremity fractures, but polymers and ceramics are showing increasing promise for these types of applications. An understanding of these materials and their compatibility with various 3D printers is essential for application of this technology in a healthcare setting.

Comparison of Fracture Location and Extent of Comminution in Isolated Scaphoid Fractures Versus Transscaphoid Fracture-Dislocations.

Background: Isolated scaphoid fractures (ISFs) are common, whereas transscaphoid fracture-dislocations (TSFDs) are not. Scaphoid fracture location and the extent of comminution are factors that affect treatment and outcome. The purpose of this study is to compare the radiographic characteristics of ISFs with TSFDs associated with greater arc injury. Methods: This study is a retrospective review of all ISFs and TSFDs that presented to our institution during a 5-year period. Fracture location (along the long axis of the scaphoid) was calculated by dividing the distance from the proximal pole to the fracture by the entire length of the scaphoid. The extent of comminution was measured in millimeters along the mid-axis of the scaphoid and divided by the entire length of the scaphoid. Results: One-hundred thirty-eight scaphoid fractures in 137 patients were identified. One-hundred twelve fractures (81%) were ISFs, and 26 (19%) were associated with a TSFD. The mean fracture location was more proximal in TSFDs than in ISFs. However, fractures occurred in the distal third of the scaphoid in 12% of ISFs compared with 0% of TSFDs. Nine percent of ISFs demonstrated comminution as compared with 12% of TSFDs. Extent of comminution was 16% and 28% for ISFs and TSFDs, respectively. Conclusion: Scaphoid fractures associated with greater arc injuries are located more proximally and are more comminuted than ISFs, and distal pole fractures rarely occur in the setting of TSFDs. The increased incidence and extent of comminution in TSFDs may be suggestive of a higher energy injury mechanism.

Systematic Surgical Approach to Alar Base Surgery in Rhinoplasty.

In an era with smartphone photography and social media (specifically, "selfies"), basal view aesthetics is becoming increasingly important. Achieving balance between the nasal base and the remainder of the nose and face while preserving or restoring external valve function are essential to a successful rhinoplasty. Without a systematic approach to the nasal base, it is more difficult to achieve an ideal outcome from both aesthetic and functional standpoints. This article outlines an organized and systematic approach to the nasal base, beginning with comprehensive nasofacial analysis. The authors continue by describing idealized basal view aesthetics and provide a treatment algorithm for common deformities that include alar flaring and a wide nasal base. The authors attempt to provide a comprehensive approach to the treatment of the nasal base by discussing the implications of treating columellar deformities, tip positioning, or alar-columellar discrepancies on the overall aesthetics of the lower third of the nose. Furthermore, technical considerations are given for common surgical maneuvers addressing the alar base to help guide treatment and prevent complications such as poor scarring, notching, nostril asymmetry or stenosis (external valve obstruction), and alar deformities ("parenthesis" or "bowling pin"), to name a few.