Wrist Motion Assessment in Tennis Players using Three-Dimensional Motion Capture and Dynamic Electromyography.

Background Tennis players often present with ulnar-sided wrist pain, which may reflect repetitive stress and/or faulty mechanics. There is a role for investigating the biomechanics of tennis strokes and how they may relate to wrist pathology. The purpose of this study was to investigate whether three-dimensional motion capture technology and dynamic electromyography (EMG), when used to study groundstrokes in elite junior tennis players, reveals patterns of upper extremity motion that may correlate with the development of clinically relevant pathology. Case Description Three-dimensional kinematic and EMG data were collected from two United States Tennis Association-ranked adolescent tennis players during groundstrokes. There were several observed differences in the two players' degree and timing of pronation/supination, ulnar/radial deviation, and flexion/extension during their strokes. Clinical Significance Advanced motion capture technology facilitates a nuanced understanding of complex movements involved in groundstroke production. This methodology may be useful for identifying athletes who are at risk for injury and guiding rehabilitation for players experiencing pain. Level of Evidence IV.

The role of vascularized bone grafting for scaphoid nonunions in adolescents.

A total of 26 adolescent patients were treated for scaphoid nonunion with a vascularized bone graft from either the medial femoral condyle or dorsal distal radius. There was an 85% union incidence, improved carpal alignment and a low incidence of complications.

Modified Frailty Index predicts postoperative complications following adult-acquired buried penis surgery: A retrospective cohort study.

BACKGROUND: Given that patients with morbid obesity are predisposed to frailty, we sought to determine whether the 5-Factor Modified Frailty Index (mFI-5) predicts postoperative complications following surgery for adult-acquired buried penis, and secondarily, to compare the mFI-5 to body mass index (BMI) and American Society of Anesthesiologists (ASA) status as preoperative risk stratification measures. METHODS: We included all patients who underwent surgical management for adult-acquired buried penis at an academic Level I trauma center between 2015 and 2023. A manual chart review was performed to collect data on patient demographics, modified frailty index variables, intraoperative data, postoperative outcomes, and complications. RESULTS: A total of 55 patients underwent surgical repair of adult-acquired buried penis, with 26 experiencing postoperative complications (47.3%). Univariable regression analyses revealed that the mFI-5 was a significant predictor of postoperative complications (odds ratio [OR] 3.40, 95% confidence interval [CI]: 1.56-7.42, p = .002), ongoing postoperative urinary problems (OR 2.03, 95% CI: 1.02-4.05, p = .045), patient dissatisfaction with outcomes (OR 3.29, 95% CI: 1.35-8.02, p = .009), and persistent postoperative symptoms (OR 2.42, 95% CI: 1.10-5.35, p = .029). There was no significant association between ASA classification and postoperative complications (OR 1.59, 95% CI:.544-4.63, p = .398). Multivariable analysis demonstrated that the mFI-5 was an independent predictor of postoperative complications (OR 5.34, 95% CI: 1.80-15.9, p = .003) when controlling for BMI and age. CONCLUSION: The mFI-5 is an independent predictor of postoperative complications in patients undergoing surgical repair of adult-acquired buried penis. The simplicity of the index permits efficient preoperative risk stratification of adult-acquired buried penis patients and provides important counseling information that may not be reflected by age or BMI alone.

Expanding Our Role in Headache Management: A Systematic Review and Algorithmic Approach to Surgical Management of Postcraniotomy Headache.

BACKGROUND: Chronic postcraniotomy headache (PCH) is common and debilitating. Unfortunately, the literature on this topic is sparse without clear management algorithms. Possible etiologies of PCH include nerve injury and/or entrapment, hardware, dural adhesions, or musculoskeletal injury. The purpose of this study was to present the results of both a systematic review of the literature and a single-center case series, both of which informed the development of a novel treatment algorithm that may be applied to this patient population. METHODS: Using Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we performed a systematic review of the literature, identifying articles describing the surgical management of PCH. A retrospective chart review was performed to identify patients who met the criteria for PCH treated at our institution. A patient's history and physical examination determined the etiology and management, and pain severity scores were the primary outcome measured. RESULTS: Nineteen articles encompassing 131 patients described surgical management techniques for PCH. 83 patients (63.3%) had complete resolution of pain (χ2 = 52.1, P < 0.0001). At our institution, 19 patients underwent surgical management for PCH. A significant reduction in pain scores from 7.57 to 2.16 (P < 0.001) was demonstrated, and 84 percent of patients achieved complete or significant pain reduction. CONCLUSIONS: Through a literature review and our own case series, we demonstrate that surgical management of PCH can achieve remarkable results. Plastic surgeons, with their expanding role in treating migraine and headaches, are well suited to manage these patients. We present an algorithmic approach to simplify the management of this common and debilitating condition.

"Postoperative Outcomes Following Buried Penis Reconstruction: A Single-Institution Experience Using the Wisconsin Classification System".

BACKGROUND: Adult acquired buried penis (AABP) is a complex condition often necessitating surgical intervention. This study seeks to examine the validity of the Wisconsin Classification System (WCS) in guiding the surgical management of AABP. Additionally, we aimed to identify which factors contribute to postoperative complications and persistent symptoms following AABP repair. METHODS: We retrospectively reviewed all patients who underwent surgical repair of AABP from 2015-2021 by the senior author at our institution. Patients were categorized according to anatomic characteristics using the WCS. Preoperative symptoms, postoperative symptoms, and postoperative complications were evaluated. RESULTS: Fifty-two patients underwent AABP repair. The mean age was 56.5±14.8 years, and the mean duration of follow-up was 350.0±517.4 days. The assigned preoperative WCS score was congruent with operative management in most patients (86.0%). Morbid obesity (BMI>40.0kg/m2) and postoperative complications were associated with persistent symptoms following AABP repair (p=0.026 and p=0.021, respectively). Increased WCS score was not associated with persistent postoperative symptoms (p=0.314). Morbid obesity (p=0.003), diabetes (p=0.029) and having a panniculectomy during AABP repair (p=0.046) increased the odds for developing postoperative complications. Patients with Type I AABP had significantly fewer complications than those with Type II, III, or IV (p=0.032). CONCLUSIONS: The Wisconsin Classification System serves as a preoperative guide, an educational tool for patients, and provides a framework for the discussion of intraoperative maneuvers and the likelihood of complications. It is imperative to counsel patients on the surgical management of AABP and the postoperative course, as this may permit realistic patient expectations and optimize outcomes.

Measuring Success in Headache Surgery: A Comparison of Different Outcomes Measures.

BACKGROUND: Studies of migraine surgery have relied on quantitative, patient-reported measures like the Migraine Headache Index (MHI) and validated surveys to study the outcomes and impact of headache surgery. It is unclear whether a single metric or a combination of outcomes assessments is best suited to do so. METHODS: All patients who underwent headache surgery had an MHI calculated and completed the Headache Impact Test, the Migraine Disability Assessment Test, the Migraine-Specific Quality-of-Life Questionnaire, and an institutional ad hoc survey preoperatively and postoperatively. RESULTS: Twenty-seven patients (79%) experienced greater than or equal to 50% MHI reduction. MHI decreased significantly from a median of 210 preoperatively to 12.5 postoperatively (85%; P < 0.0001). Headache Impact Test scores improved from 67 to 61 (14%; P < 0.0001). Migraine Disability Assessment Test scores improved from 57 to 20 (67%; P = 0.0022). The Migraine-Specific Quality-of-Life Questionnaire demonstrated improvement in quality-of-life scores within all three of its domains ( P < 0.0001). The authors' ad hoc survey demonstrated that participants "strongly agreed" that (1) surgery helped their symptoms, (2) they would choose surgery again, and (3) they would recommend headache surgery to others. CONCLUSIONS: Regardless of how one measures it, headache surgery is effective. The authors demonstrate that surgery significantly improves patients' quality of life and decreases the effect of headaches on patients' functioning, but headaches can still be present to a substantial degree. The extent of improvement in migraine burden and quality of life in these patients may exceed the amount of improvement demonstrated by current measures.

Abductor Pollicis Longus Tendon Abnormalities and Release in Children With Congenital Clasped Thumb.

BACKGROUND: Congenital clasped thumb is associated with deficient thumb extensor tendons. Reconstruction includes tendon transfer. Here, we describe a variant of the abductor pollicis longus (APL) tendon, not previously reported, contributing to the flexion deformity. The purpose of this study is to report examples of and offer surgical repair techniques for APL variants identified in patients with clasped thumb. METHODS: We reviewed records of 11 consecutive patients undergoing reconstruction for clasped thumb. Surgical anatomy of the APL tendon was evaluated in all patients, followed by release of aberrant APL attachments. Participants were invited to return for an in-person assessment with a certified hand therapist. Data were collected regarding intraoperative findings, surgical techniques for reconstruction, postoperative thumb motion, and patient and caregiver satisfaction. RESULTS: Eleven children (12 thumbs) underwent aberrant APL release and rerouting between 2019 and 2021. Preoperatively, all thumbs were passively correctible to 0° of extension. In all patients, the APL was found to terminate palmar to the metacarpophalangeal (MCP) joint, creating an MCP flexion moment when tensioned. The average age at surgery was 7 years (range: 1-15 years), and the average follow-up was 14.2 months (range: 1-21 months). The mean postoperative thumb radial abduction was 55° (range: 20°-75°). CONCLUSIONS: When reconstructing clasped thumbs, surgeons should explore the presence of APL abnormalities. Release and centralization of the APL can improve thumb position and function. This technique may avoid the need for extra-anatomical tendon transfer in patients with clasped thumb.

Local Environment Induces Differential Gene Expression in Regenerating Nerves.

INTRODUCTION: Approximately 80% of amputations are complicated by neuromas. Methods for neuroma management include nerve translocation into bone and implantation into skeletal muscle grafts, which have also facilitated the development of regenerative neural interfaces to enable fixation of prosthetics with motor and sensory feedback. However, molecular-level differences between nerves in these environments have not been investigated. This study aimed to elucidate the physiology of regenerating nerves in different settings by assessing gene expression. MATERIALS AND METHODS: New Zealand white rabbits underwent transfemoral amputation with sciatic nerve transposition into the femur or tacked to skeletal muscle. At 5 wk, ribonucleic acid (RNA) sequencing of samples of distal nerve terminating in bone or muscle and nerve of the contralateral limb (control) identified differentially expressed genes (DEGs) and biochemical pathways (α = 0.05). RESULTS: Three samples of nerve housed in bone, four of nerve tacked to muscle, and seven naïve controls were analyzed. Relative to controls, nerve housed in bone had little within-group variation and 13,028 DEGs, and nerve tacked to muscle had dramatic within-group variation and 12,811 DEGs. These samples upregulated the following pathways: lysosome, phagosome, antigen processing/presentation, and cell adhesion molecule. Relative to nerve housed in bone, nerve tacked to muscle had 12,526 DEGs, demonstrating upregulation of pathways of B-cell receptor signaling, focal adhesion, natural killer-cell mediated cytotoxicity, leukocyte transendothelial migration, and extracellular matrix-receptor interactions. CONCLUSIONS: Nerve housed in bone has a more predictable molecular profile than does nerve tacked to muscle. Thus, the intramedullary canal may provide a more reliable setting for neuroma prevention and neural interfacing.

The Effect of Tension on Gene Expression in Primary Nerve Repair via the Epineural Suture Technique.

INTRODUCTION: The precise mechanism through which excessive tension confers poor outcomes in nerve gap repair is yet to be elucidated. Furthermore, the effect of tension on gene expression in regenerating nerves has not been characterized. This study investigated differential gene expression in transected nerves repaired under high and minimal tension. METHODS: Male Lewis rats underwent right sciatic nerve transection with either minimal-tension or high-tension repair. Fourteen weeks postoperatively, segments of the right sciatic nerves were harvested along with equal-length segments from the contralateral, healthy nerve to serve as internal controls (naïve nerve). Differentially expressed genes (DEGs) and differentially regulated biochemical pathways between the samples were identified. RESULTS: Seventeen animals were studied. The gene expression profiles of naïve nerve and minimal-tension repair demonstrated minimal within-group variation, whereas that of high-tension repair demonstrated heterogeneity. Relative to naïve nerve, high-tension repair samples had 4276 DEGs (1941 upregulated and 2335 downregulated) and minimal-tension repair samples had 3305 DEGs (1479 upregulated and 1826 downregulated). High-tension repair samples had 360 DEGs relative to minimal-tension repair samples (68 upregulated and 292 downregulated). Upregulated biological pathways in all repaired nerves included steroid biosynthesis, extracellular matrix-receptor interaction, and ferroptosis. Finally, upregulated pathways in high-tension repair samples relative to minimal-tension repair samples included tumor necrosis factor signaling, interleukin-17 signaling, cytokine-cytokine receptor interaction, and mitogen-activated protein kinase signaling. CONCLUSIONS: The improved outcomes achieved with minimal-tension nerve repair may take root in a favorable gene expression profile. Future elucidation of biochemical pathways in nerve regeneration may identify potential therapeutic targets to optimize primary nerve repair outcomes.

Systematic Review of Replant Salvage and Cost Utility Analysis of Inpatient Monitoring After Digit Replantation.

PURPOSE: Digit replantation is a high-stakes procedure that has been shown to be cost-effective, especially for multiple-digit replantation. However, it is associated with prolonged lengths of stay (LOS) for monitoring and attempts at salvage. The cost-effectiveness of prolonged inpatient stays presumes that this is necessary and inherent to the replantation. We hypothesized that prolonged monitoring of replanted digits, in the hope of possible salvage after primary failure, is cost-ineffective due to the low rates of vascular compromise and salvage after replantation. METHODS: Using previously published data comparing quality adjusted life years lost after traumatic digit amputation versus digit replantation, we devised a cost utility model to evaluate the incremental cost-effectiveness ratio of inpatient monitoring. To determine rates of vascular compromise and salvage after digit replantation, we performed a systematic review of the literature through MEDLINE and SCOPUS database searches to identify relevant articles on digital replantation since 1990. Cost-effectiveness was stratified based on the number of digits replanted. RESULTS: Fewer than 9% of replanted digits both experience vascular compromise and are successfully salvaged. Adjusting for this, inpatient monitoring for single-digit and thumb replantation becomes cost-ineffective after 1 day of admission and monitoring for multiple-digit replantation becomes cost-ineffective after 2 days of admission. CONCLUSIONS: In the United States, prolonged admissions for inpatient monitoring quickly become cost-ineffective, especially with relatively low rates of salvage. Surgeons should avoid extended hospitalizations for replant monitoring and should pursue enhanced recovery protocols for replantation, especially considering burgeoning health care costs in the United States. TYPE OF STUDY/LEVEL OF EVIDENCE: Economic/Decision Analysis III.

Transradial Amputation With Pedicled Pronator Quadratus Interposition and Advanced Neuroma-Prevention Techniques.

Transradial amputation is a reconstructive option for upper-extremity trauma, infection, malignancy, and ischemia. The possible postoperative complications include residual radioulnar impingement and the development of a painful neuroma. In this report, a pedicled pronator quadratus flap interposition between the distal radius and ulna has been described. Additionally, various techniques to mitigate the development of symptomatic neuromas have been described.

Qualitative Analysis of Single-Site Headache Surgery: Is It Different From Multiple-Site Surgery?

BACKGROUND: Migraine surgery has been shown to be efficacious, but nuanced effects of surgery on pain and individuals' lives remain incompletely understood. Surgery may be performed at a single or multiple "primary" sites. The aims of this study were to investigate patient perceptions following single-site surgery and compare themes in patients undergoing single-site surgery with those from a previously published conceptual framework generated with patients undergoing multisite surgery. METHODS: Patients who underwent single-site headache surgery participated in open-ended interviews at least 1 year after surgery. Participants (n = 14) had undergone either occipital, temporal, or nasoseptal site surgery. A multidisciplinary team analyzed transcripts. Recurring themes were identified and compared and contrasted to those observed in patients who underwent multiple-site surgery (n = 15) in a previous study (Plast Reconstr Surg 2019;144(4):956-964). RESULTS: Similar recurring themes emerged from the single-site cohort, and the conceptual framework was applicable to all participants. Two new themes emerged from the single-site analysis. First, 5 of 14 participants described being "migraine-free" postoperatively, a finding not observed in the multisite group. Second, several individuals described financial benefits after surgery, via decreased prescription medication requirements, raises at work, and improved productivity. CONCLUSIONS: Single-site headache surgery appears to positively impact patients' lives in ways that support and expand upon previously published outcomes. Patients undergoing surgery at a single site may be more likely to experience a "pain-free" state, which may relate to the underlying pathophysiology of chronic headache. The effect of surgery on finances appears to be an outcome of interest to patients, which should be explored further.

Recovery and Regrowth After Nerve Repair: A Systematic Analysis of Four Repair Techniques.

BACKGROUND: Outcome assessments that evaluate post-transection nerve repair do not often correlate with one another. The aims of this study were twofold: to compare four nerve repair techniques with each other and incorporate both negative and positive control groups and to identify possible correlations between outcome assessments. MATERIALS AND METHODS: Sciatic nerve transection and repair was performed in Lewis rats using one of the following techniques: interrupted epineural, running epineural, grouped fascicular, epineural with absorbable type I collagen wrap, and high tension for incorporation of a negative control. A sham surgery group was also included as a positive control group. Outcomes were compared using assessments of functional recovery (behavior and electrophysiology) and nerve regrowth (imaging and histomorphometry). Three-dimensional printed custom electrode stabilization and imaging devices were designed and fabricated to provide standardization in assessment between subjects. RESULTS: Nerve repair was performed in 48 male Lewis rats. In all animals, functional testing was performed at week 13. The sham group (n = 7) performed the best on both behavioral assays (P < 0.001) and electrophysiology assessments (P < 0.001). The negative control group (high tension) performed poorest on multiple assessments, and there were no significant differences observed for any of the four repair types. Positive correlations were observed between behavioral and histomorphometric tests. CONCLUSIONS: There was no difference in outcome between the four types of nerve repair. High-tension nerve repair represents an ideal negative control. Not all assessment methods correlate equally, and consistent use of complimentary outcome assessments could allow for improved comparison between studies.

Medicaid for the Plastic and Reconstructive Surgeon.

Medicaid is a complex federally and state funded health insurance program in the United States that insures an estimated 76 million individuals, approximately 20 percent of the U.S. population. Many physicians may not receive formal training or education to help understand the complexities of Medicaid. Plastic surgeons, residents, and advanced practice practitioners benefit from a basic understanding of Medicaid, eligibility requirements, reimbursement methods, and upcoming healthcare trends. Medicaid is implemented by states with certain federal guidelines. Eligibility varies from state to state (in many states it's linked to the federal poverty level), and is based on financial and nonfinancial criteria. The passage of the Affordable Care Act in 2010 permitted states to increase the federal poverty level eligibility cutoff to expand coverage for low-income adults. The aim of this review is to provide a brief history of Medicaid, explain the basics of eligibility and changes invoked by the Affordable Care Act, and describe how federal insurance programs relate to plastic surgery, both at academic institutions and in community practice environments.

Challenging Traditional Thinking: Early Free Tissue Transfer for Active Hemifacial Atrophy in Children.

BACKGROUND: Hemifacial atrophy (Parry-Romberg syndrome) is an enigmatic craniofacial disorder characterized by progressive facial atrophy. Early age at onset is associated with significant skeletal involvement and jaw abnormalities. Standard reconstructive dogma dictates that the disease should "burn out," with at least 2 years of no disease progression, before pursuing reconstructive intervention. The purpose of this article is to present the senior author's (J.W.S.) experience treating preadolescent children with free soft-tissue transfer for reconstruction of progressing hemifacial atrophy, and to review surgical techniques in this patient population. METHODS: Pediatric free tissue transfer cases performed by the senior author were reviewed. Free tissue transfer using a circumflex scapular adipofasciocutaneous flap was performed to treat deformities arising from hemifacial atrophy. RESULTS: Thirty-six patients aged 3 to 6 years underwent free tissue transfer in the presence of progressing, active disease. Follow-up ranged from 7 months to 25 years. There were no cases of flap loss. In all patients, the disease process seemed to be altered, with no symptoms recurring to date. CONCLUSIONS: The authors believe that early microsurgical correction of hemifacial atrophy in children as young as 3 years is reliable and effective. The authors theorize that the interposition of vascularized, healthy tissue may alter or even halt the progression of disease, and may also prevent the skeletal hypoplasia classically seen in older patients. Further study incorporating autologous fat grafting as a control procedure may provide additional insight into this challenging disease process. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Targeted Muscle Reinnervation in the Hand: Treatment and Prevention of Pain After Ray Amputation.

Targeted muscle reinnervation (TMR), originally developed as an experimental technique for prosthetic control, has been shown to be safe and effective for the treatment and prevention of postamputation pain. Targeted muscle reinnervation involves coaptation of residual nerve ends to nearby motor nerve branches of healthy but expendable muscles proximal to an amputation. It has been shown to prevent and reduce residual limb pain and phantom limb pain after major upper and lower extremity amputation. However, the use of this technique has not been described distal to the forearm because bioprosthetic use is not a consideration at that level. The aim of this article was to (1) present 2 cases of TMR performed in the setting of ray amputation, and (2) provide technical strategies for maximizing success and efficiency.

Methodology for creating a chronic osseointegrated neural interface for prosthetic control in rabbits.

BACKGROUND: Chronic stability and high degrees of selectivity are both essential but somewhat juxtaposed components for creating an implantable bi-directional PNI capable of controlling of a prosthetic limb. While the more invasive implantable electrode arrays provide greater specificity, they are less stable over time due to compliance mismatch with the dynamic soft tissue environment in which the interface is created. NEW METHOD: This paper takes the surgical approach of transposing nerves into bone to create neural interface within the medullary canal of long bones, an osseointegrated neural interface, to provide greater stability for implantable electrodes. In this context, we describe the surgical model for transfemoral amputation with transposition of the sciatic nerve into the medullary canal in rabbits. We investigate the capacity to create a neural interface within the medullary canal histolomorphologically. In a separate proof of concept experiment, we quantify the chronic physiological capacity of transposed nerves to conduct compound nerve action potentials evoked via an Osseointegrated Neural Interface. COMPARISON WITH EXISTING METHOD(S): The rabbit serves as an important animal model for both amputation neuroma and osseointegration research, but is underutilized for the exploration neural interfacing in an amputation setting. RESULTS: Our findings demonstrate that transposed nerves remain stable over 12 weeks. Creating a neural interface within the medullary canal is possible and does not impede nerve regeneration or physiological capacity. CONCLUSIONS: This article represents the first evidence that an Osseointegrated Neural Interface can be surgically created, capable of chronic stimulation/recording from amputated nerves required for future prosthetic control.

"Like a Normal Person Again": A Qualitative Analysis of the Impact of Headache Surgery.

BACKGROUND: Outcomes after migraine surgery have been previously assessed using quantitative measurements, including the migraine headache index. Qualitative methodologies offer the ability to analyze patients' perceptions and pain experience, and may point to changes in domains not captured by quantitative instruments. The purpose of this study was to characterize individual patients' experiences with migraines and to analyze how patients' experience of headaches changes in relation to surgery. METHODS: Patients who previously underwent migraine surgery performed by a single surgeon participated in semistructured interviews at least 1 year after surgery. Purposive sampling was used to recruit patients [n = 15 (73 percent female)]. Interviews were transcribed verbatim. A multidisciplinary team with backgrounds in surgery, pain management, medicine, and health services research coded and analyzed transcripts. RESULTS: Participants reported improvements in one or more domains of pain following surgery, and changes in medication use and effectiveness. Even in individuals with persistent pain postoperatively, surgery appeared to facilitate an improvement in headache self-efficacy, including an ability to participate in daily activities. Migraineurs frequently described a new degree of control over at least one aspect of their pain. CONCLUSIONS: Migraine surgery appears to positively impact patients' lives in ways that support and expand on previously published outcomes. Patients report benefiting from surgery in ways that are not currently captured in commonly used metrics. This study's findings support the need for more specific patient-reported outcome measures to help clinicians and patients understand the impact of surgery and which outcomes matter most to patients.

Major Histocompatibility Complex-Matched Arteries Have Similar Patency to Autologous Arteries in a Mauritian Cynomolgus Macaque Major Histocompatibility Complex-Defined Transplant Model.

Background Arterial bypass and interposition grafts are used routinely across multiple surgical subspecialties. Current options include both autologous and synthetic materials; however, each graft presents specific limitations. Engineering artificial small-diameter arteries with vascular cells derived from induced pluripotent stem cells could provide a useful therapeutic solution. Banking induced pluripotent stem cells from rare individuals who are homozygous for human leukocyte antigen alleles has been proposed as a strategy to facilitate economy of scale while reducing the potential for rejection of induced pluripotent stem cell-derived transplanted tissues. Currently, there is no standardized model to study transplantation of small-diameter arteries in major histocompatibility complex-defined backgrounds. Methods and Results In this study, we developed a limb-sparing nonhuman primate model to study arterial allotransplantation in the absence of immunosuppression. Our model was used to compare degrees of major histocompatibility complex matching between arterial grafts and recipient animals with long-term maintenance of patency and function. Unexpectedly, we (1) found that major histocompatibility complex partial haplomatched allografts perform as well as autologous control grafts; (2) detected little long-term immune response in even completely major histocompatibility complex mismatched allografts; and (3) observed that arterial grafts become almost completely replaced over time with recipient cells. Conclusions Given these findings, induced pluripotent stem cell-derived tissue-engineered blood vessels may prove to be promising and customizable grafts for future use by cardiac, vascular, and plastic surgeons.