Hirayama Disease: Surgical Restoration of Hand Function.

PURPOSE: Hirayama disease (HD) is a rare, nonfamilial, self-limiting, progressive lower cervical myelopathy, resulting in debilitating distal upper-extremity motor deficits, mimicking high ulnar neuropathy, lower trunk brachial plexopathy, or C8-T1 radiculopathy. Although most literature focuses on pathophysiology and prevention of disease progression, there remains limited discussion regarding treatment to improve upper-extremity function in patients with stable disease. The upper-extremity manifestations of HD are reviewed along with surgical options for restoring hand function. METHODS: A retrospective review of patients with HD who underwent reconstruction to improve hand function was undertaken. Demographic data, preoperative electrodiagnostic and electromyographic, and physical examination findings were collected. Outcome data involved postoperative grip, pinch, and functional assessment documented on clinical visits. Qualitative descriptions of the surgical techniques are described. RESULTS: Among six patients identified, four met the inclusion criteria and underwent tendon transfers and selected joint arthrodeses. All patients were diagnosed as teenagers, were right hand-dominant, and three were male. Unilateral symptoms were present in one patient and were bilateral in the rest. All patients were treated with tendon transfers for thumb opposition, grasp, anticlaw, and thumb interphalangeal joint arthrodesis. All patients had postoperative grip strength improvement. The average follow-up was 3.2 years. CONCLUSIONS: Hirayama disease is a rare disease often managed by spine surgeons and neurologists who may be unaware of options for restoring hand function deficits. Technical strategies and outcomes of improving hand function in HD have not been adequately described. Surgical options to improve hand function are tailored to the deficits and include tendon transfers, select joint arthrodeses, and/or tenodeses. Risk of disease progression and expectations following hand reconstruction must be managed carefully. TYPE OF STUDY LEVEL OF EVIDENCE: Therapeutic V.

Validation of the Root Analysis Score for C5 Viability in Patients With Pan-Brachial Plexus Injury.

PURPOSE: Pan-brachial plexus injury patients present a reconstructive challenge. The root analysis score, developed from parsimonious multivariable modeling of 311 pan-brachial plexus injury patients, determines the probability of having a viable C5 nerve based on four categories: positive C5 Tinel test, intact C5 nerve on computed tomography myelogram, lack of hemidiaphragmatic elevation, and absence of midcervical paraspinal fibrillations. METHODS: Root analysis scores were calculated for a separate cohort of patients with pan-brachial plexus injuries. Scores were validated by the presence or absence of a graftable C5 root, based on supraclavicular exploration and intraoperative electrophysiologic testing. Receiver operating characteristic curve, accuracy, and concordance statistic of the scores were calculated. Patients were divided into three root analysis score cohorts: less than 50 (low), 50-75 (average), and 75-100 points (high) based on dividing the score into quartiles and combining the lowest two. The probability, sensitivity, and specificity of each cohort having an available C5 nerve were based on the intraoperative assessment. RESULTS: Eighty patients (mean age, 33.1 years; 15 women and 65 men) were included. Thirty-one patients (39%) had a viable C5 nerve. The root analysis calculator had an overall accuracy of 82.5%, a receiver operating characteristic of 0.87, and a concordance statistic of 0.87, demonstrating high overall predictive value; 6.5% of patients with a score of less than 50 (94% sensitivity and 43% specificity), 16.1% of patients with a score of 50-75 (94% sensitivity and 67% specificity), and 77.4% of patients with a score of 75-100 (77% sensitivity and 90% specificity) had a graftable C5 nerve. CONCLUSIONS: The root analysis score demonstrated high accuracy and predictive power for a viable C5 nerve. In patients with a score of less than 50, the necessity of supraclavicular root exploration should balance patient factors, presentation timing, and concomitant injuries. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnosis II.

Superficial Branch of the Radial Nerve Versus Sural Nerve Grafting After Traumatic Adult Brachial Plexus Injury.

The purpose of this study was to compare two sources of nerve graft for brachial plexus reconstruction: the denervated superficial branch of the radial nerve (SBRN) and the sural nerve. Ninety-seven patients who underwent brachial plexus reconstruction with denervated SBRN nerve (24 patients with 24 grafts) or with sural nerve grafting (73 patients with 83 nerve grafts) were included. The two groups were compared with respect to postoperative muscle reinnervation, disabilities of the arm, shoulder, and hand (DASH) scores. In the SBRN group, only four (17%) of the nerve grafts provided grade III or higher muscle function. In the sural nerve group, 31 (37%) of the nerve grafts provided grade III or higher muscle function. Smoking had a negative impact on muscle recovery. Denervated SBRN grafts are associated with inferior outcomes when compared with sural nerve grafts in the treatment of traumatic adult brachial plexus injuries. (Journal of Surgical Orthopaedic Advances 33(2):080-083, 2024).

The diagnostic utility of inspiratory-expiratory radiography for the assessment of phrenic nerve palsy associated with brachial plexus injury.

BACKGROUND: The phrenic nerve is commonly injured with trauma to the brachial plexus. Hemi-diaphragmatic paralysis may be well-compensated in healthy individuals at rest but can be associated with persistent exercise intolerance in some patients. This study aims to determine the diagnostic value of inspiratory-expiratory chest radiography compared to intraoperative stimulation of the phrenic nerve for assessing phrenic nerve injury associated with brachial plexus injury. METHODS: Over a 21-year period, the diagnostic utility of three-view inspiratory-expiratory chest radiography for identification of phrenic nerve injury was determined by comparison to intraoperative phrenic nerve stimulation. Multivariate regression analysis was used to identify independent predictors of phrenic nerve injury and having an incorrect radiographic diagnosis. RESULTS: A total of 237 patients with inspiratory-expiratory chest radiography underwent intraoperative testing of phrenic nerve function. Phrenic nerve injury was present in approximately one-fourth of cases. Preoperative chest radiography had a sensitivity of 56%, specificity of 93%, positive predictive negative of 75%, and negative predictive value of 86% for identification of a phrenic nerve palsy. Only C5 avulsion was found to be a predictor of having an incorrect diagnosis of phrenic nerve injury on radiography. CONCLUSION: While inspiratory-expiratory chest radiography has good specificity for detecting phrenic nerve injuries, a high number of false negatives suggest that it should not be relied upon for routine screening of dysfunction after traumatic brachial plexus injury. This is likely multifactorial and relates to variation in diaphragm shape and position, as well as limitations regarding static image interpretation of a dynamic process.

Surgical management of peroneal nerve injuries.

BACKGROUND: Traumatic peroneal nerve injuries are typically associated with high-energy injuries. The aim of this study was to evaluate the demographics and outcomes following surgical management of peroneal nerve injuries. METHODS: Patients evaluated at a single institution with peroneal nerve injuries between 2001 and 2022 were retrospectively reviewed. Mechanism of injury, time to surgery, pre- and postoperative examinations, and operative reports were recorded. Satisfactory outcome, defined as the ability to achieve anti-gravity dorsiflexion strength or stronger following surgery, was compared between nerve grafting and nerve transfers in patients with at least 9 months of postoperative follow-up. RESULTS: Thirty-seven patients had follow-up greater than 9 months after surgery, with an average follow-up of 3.8 years. Surgeries included neurolysis (n=5), direct repair (n=2), tibial motor nerve fascicle transfer to the anterior tibialis motor branch (n=18), or interposition nerve grafting using sural nerve autograft (n=12). At last follow-up, 59.5% (n=22) of patients had anti-gravity strength or stronger dorsiflexion. Nineteen (51.4%) patients used an ankle-foot orthosis during all or some activities. In patients that underwent nerve grafting only across the peroneal nerve defect, 44.4% (n=4) were able to achieve anti-gravity strength or stronger dorsiflexion. In patients that had a tibial nerve fascicle transfer to the tibialis anterior motor branch of the peroneal nerve, 42.9% (n=6) were able to achieve anti-gravity strength or stronger dorsiflexion at last follow-up. There was no statistical difference between nerve transfers and nerve grafting in postoperative dorsiflexion strength (p = 0.51). CONCLUSION: Peroneal nerve injuries frequently occur in the setting of knee dislocations and similar high-energy injuries. Nerve surgery is not universally successful in restoration of ankle dorsiflexion, with one-third of patients requiring an ankle-foot orthosis at mid-term follow-up. Patients should be properly counseled on the treatment challenges and variable outcomes following peroneal nerve injuries.

Stem cell therapy for traumatic brachial plexus injury.

Stem cell therapy is rapidly evolving, with preclinical studies showing various stem cell types successfully promoting peripheral nerve regeneration. Despite the lack of clinical studies demonstrating efficacy and safety, the number of commercial entities marketing and promoting this treatment direct to patients is also increasing. We describe three adult traumatic brachial plexus injury (BPI) patients who had stem cell therapies prior to consultation in a multidisciplinary brachial plexus clinic. No functional improvement was noted at long-term follow-up despite claims reported by the commercial entities. Considerations and implications of stem cell application in BPI patients are reviewed.

Osteochondral Autograft Transplantation for Proximal Pole Scaphoid Nonunions.

PURPOSE: Osteochondral autograft transplantation (OAT) is a technique to reconstruct the proximal pole scaphoid nonunion associated with an intact dorsal and volar scapholunate ligament. This study aimed to report the clinical and radiographic outcomes in patients who underwent OAT for this indication. METHODS: A retrospective review of patients who underwent proximal pole scaphoid nonunion reconstruction with a femoral trochlea OAT was undertaken between 2018 and 2022. Patient demographics, scaphoid nonunion characteristics, surgery details, and clinical and radiographic outcomes were obtained. RESULTS: Eight patients underwent the procedure at an average of 18.2 months from injury. Four patients failed prior attempts at scaphoid union surgery, one of whom failed two prior surgeries. Four had no prior surgery. The average follow-up was 11.8 months. The postoperative wrist flexion-extension arc of motion was 125° or 87% of the contralateral wrist. Grip strength averaged 30.0 kg or 86% of the contralateral side. Adjusted grip strength for hand dominance was 81% of the contralateral side. All OATs healed. Computed tomography scan confirmed the union in 6 patients between 6 and 10 weeks. Two patients whose radiographs demonstrated OAT incorporation at the time of follow-up did not undergo advanced imaging. CONCLUSIONS: Osteochondral autograft transplantation is an attractive surgical reconstructive procedure for patients with proximal pole scaphoid nonunions associated with an intact scapholunate ligament. Osteochondral autograft transplantation mitigates the need for vascularized bone grafting, has a rapid time to osseous incorporation, and has a simple postoperative course in which patients can expect early union, near-full range of motion, and grip strength. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Triceps-to-Biceps Tendon Transfer for Restoration of Elbow Flexion in Brachial Plexus Injury.

PURPOSE: Restoring elbow flexion is a reconstructive priority in patients with brachial plexus injuries. This study aimed to evaluate the results and assess factors contributing to outcomes of triceps-to-biceps tendon transfer in patients presenting with delayed or chronic upper brachial plexus injury. METHODS: Patients with traumatic brachial plexus injuries undergoing triceps-to-biceps tendon transfer at a single institution's multidisciplinary brachial plexus center between 2001 and 2021 were retrospectively reviewed. The entire triceps tendon was transferred around the lateral aspect of the arm, secured to the radius with a tenodesis button, and reinforced with a side-to-side tendon transfer to the biceps tendon. Primary outcomes include the modified British Medical Research Council (mBMRC) elbow flexion strength and active elbow range of motion. RESULTS: Twelve patients (eight men and four women; mean age, 45.2 years) were included. The mean follow-up was 10.4 (range, 5-34) months. Nine patients achieved mBMRC ≥3. Five patients achieved mBMRC 4. Average active elbow flexion was 119°, with average extension deficit of 11°. There were three patients with unsatisfactory results, achieving mBMRC 2 elbow flexion. CONCLUSIONS: Triceps-to-biceps tendon transfer is an excellent tendon transfer option for restoring elbow flexion in certain patients with an adequately functioning triceps muscle, who present with a delayed or chronic brachial plexus injury. Although most patients achieved mBMRC ≥3 elbow flexion, there was an expected permanent loss of elbow active extension with a residual elbow flexion contracture. LEVEL OF EVIDENCE: Therapeutic IV.

Persistent and profound peripheral nerve injuries following reverse total shoulder arthroplasty.

BACKGROUND: Peripheral nerve injuries associated with reverse total shoulder arthroplasty (rTSA) are rarely reported and are often dismissed as neuropraxias, particularly in the setting of perioperative nerve blocks. The purpose of this study was to evaluate nerve injuries following rTSA to determine if there is a pattern of injury and to evaluate outcomes of patients who sustain an intraoperative nerve injury. METHODS: A retrospective review was performed identifying patients who underwent rTSA and had a concomitant major nerve injury who were referred to a multidisciplinary peripheral nerve injury clinic. Demographic data, preoperative nerve block use, physical examination, electrodiagnostic studies, injury pattern, and time from injury to referral was collected. Radiographs, Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) score, and outcomes surveys were obtained at final follow-up. RESULTS: Twenty-two patients were identified with postoperative nerve injuries. Average time from injury to referral was 9.0 months, with 18.8 months' follow-up. Eight patients had undergone prior shoulder surgery, and 11 patients had prior shoulder trauma. Injury patterns were variable and involved diffuse pan-plexopathies with severity localized to the posterior and medial cords (11), the upper trunk (5), lateral cord (2), and axillary nerve (4). The average postoperative acromiohumeral distance (AHD) was 3.7 cm, with an average change of 2.9 cm. The average postoperative lateral humeral offset (LHO) was 1.1 cm, with an average change of 0.2 cm. Seventeen patients were confirmed to have undergone preoperative nerve blocks, which were initially attributed as the etiology of nerve injury. Eighteen patients were initially treated with observation: 11 experienced residual debilitating neuropathic pain and/or disability, and 7 had substantial improvement. One patient underwent nerve transfers, whereas the others underwent procedures for hand dysfunction improvement. The average QuickDASH score was 53.5 at average of 4 years post rTSA. CONCLUSIONS: Although uncommon, permanent peripheral nerve injuries following rTSA do occur with debilitating effects. Preoperative regional blocks were used in most cases, but none of the blocks could be directly attributed to the nerve injuries. Nerve injuries were likely secondary to traction at the time of arthroplasty and/or substantial distalization and lateralization of the implants. Patients with medial cord injuries had the most debilitating loss of hand function. Surgeons should be cognizant of these injuries and make a timely referral to a peripheral nerve specialist.

Relocating the C5 nerve stump in C5 nerve grafting to prevent iatrogenic phrenic nerve injury.

BACKGROUND: Exploration and grafting of the brachial plexus remains the gold standard for post-ganglionic brachial plexus injuries that present within an acceptable time frame from injury. The most common nerves available for grafting include C5 and C6. During the surgical exposure of C5 and C6, the phrenic nerve is anatomically anterior to the cervical spinal nerves, making it vulnerable to injury while performing the dissection and nerve stump to graft coaptation. We describe a novel technique that protects the phrenic nerve from injury during supraclavicular brachial plexus exposure and grafting of C5 or upper trunk ruptures or neuromas in-continuity. METHODS: A 4-step technique is illustrated: (1) The normal anatomic relationships of the phrenic nerve anterior to C5 is displayed in the face of the traumatic scarring. (2) The C5 spinal nerve stump is then transposed from its anatomic position posterior to the phrenic nerve to an anterior position. (3) The C5 stump is then moved medially for retrograde neurolysis of C5 from its phrenic nerve contribution. The graft coaptation to C5 is performed in this medial position, which minimizes retraction of the phrenic nerve. (4) The normal anatomic relationship of the phrenic nerve and the C5 nerve graft is restored. RESULTS: We have been routinely relocating the C5 spinal nerve stump around the phrenic nerve for the past 10 years. We have experienced no adverse respiratory events. CONCLUSION: This technique facilitates surgical exposure and prevents iatrogenic injury on the phrenic nerve during nerve reconstruction.

Distal Nerve Transfers to the Triceps Brachii Muscle: Surgical Technique and Clinical Outcomes.

PURPOSE: To report the clinical outcomes and describe the surgical technique of triceps muscle reinnervation using 2 different distal nerve transfers: the flexor carpi ulnaris (FCU) fascicle of the ulnar nerve and the posterior branch of the axillary nerve (PBAN) to the triceps nerve branch. METHODS: A retrospective review of patients undergoing FCU fascicle of ulnar nerve or PBAN to triceps nerve branch transfer was performed. Outcome measures included preoperative and postoperative modified British Medical Research Council (MRC) score, EMG results, and complications. RESULTS: Between September 2003 and April 2017, 6 patients were identified. Four patients with a traumatic upper trunk and posterior cord palsy underwent ulnar nerve fascicle to triceps nerve transfer. Two patients with a recovering upper trunk following a pan-brachial plexus palsy underwent PBAN to triceps nerve branch transfer. The median age was 30.0 years (range, 18-68 years). Surgery was performed at a median of 6.9 months (range, 5.0-8.9 months) postinjury, with a median follow-up of 18.4 months (range, 7.6-176.3) months. Before surgery, 4 patients exhibited grade M0 and 2 patients exhibited grade M1 triceps strength. Four patients had M5 donor muscle strength and 2 had grade M4. Postoperatively, 4 patients regained MRC grade M4 triceps muscle strength, 1 regained M3, and 1 regained M2. There was no noticeable donor muscle weakness. CONCLUSIONS: Nerve fascicles to the FCU and PBAN are viable options for obtaining meaningful triceps muscle recovery in a select group of patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

New methods for objective angiogenesis evaluation of rat nerves using microcomputed tomography scanning and conventional photography.

INTRODUCTION: Nerve regeneration involves multiple processes, which enhance blood supply that can be promoted by growth factors. Currently, tools are lacking to visualize the vascularization patterns in transplanted nerves in vivo. The purpose of this study was to describe three-dimensional visualization of the vascular system in the rat sciatic nerve and to quantify angiogenesis of nerve reconstruction. MATERIALS AND METHODS: In 12 Lewis rats (weighing 250-300 g), 10 mm sciatic nerve gaps were repaired with ipsilateral reversed autologous nerve grafts. At 12 and 16 weeks of sacrifice, Microfil® contrast compound was injected in the aorta. Nerve autografts (N = 12) and contralateral untreated nerves (N = 12) were harvested and cleared while preserving the vasculature. The amount of vascularization was measured by quantifying the vascular surface area using conventional photography (two-dimensional) and the vascular volume was calculated with microcomputed tomography (three-dimensional). For each measurement, a vessel/nerve area ratio was calculated and expressed in percentages (vessel%). RESULTS: The vascular volume measured 3.53 ± 0.43% in autografts and 4.83 ± 0.45% vessels in controls at 12 weeks and 4.95 ± 0.44% and 6.19 ± 0.29% vessels at 16 weeks, respectively. The vascular surface area measured 25.04 ± 2.77% in autografts and 26.87 ± 2.13% vessels in controls at 12 weeks, and 28.11 ± 3.47% and 33.71 ± 2.60% vessels at 16 weeks, respectively. The correlation between both methods was statistically significant (p = .049). CONCLUSIONS: Both methods are considered to successfully reflect the degree of vascularization. Application of this technique could be used to visualize and objectively quantify angiogenesis of the transplanted nerve graft. Moreover, this simple method is easily reproducible and could be extrapolated to any other desired target organ ex vivo in small animals to investigate the vascular network.

Adipose derived mesenchymal stem cells seeded onto a decellularized nerve allograft enhances angiogenesis in a rat sciatic nerve defect model.

PURPOSE: Adipose derived mesenchymal stem cells (MSCs) are hypothesized to supplement tissues with growth factors essential for regeneration and neovascularization. The purpose of this study was to determine the effect of MSCs with respect to neoangiogenesis when seeded onto a decellularized nerve allograft in a rat sciatic nerve defect model. METHODS: Allograft nerves were harvested from Sprague-Dawley rats and decellularized. MSCs were obtained from Lewis rats. 10 mm sciatic nerve defects in Lewis rats were reconstructed with reversed autograft nerves, decellularized allografts, decellularized allografts seeded with undifferentiated MSC or decellularized allografts seeded with differentiated MSCs. At 16 weeks, the vascular surface area and volume were evaluated. RESULTS: The vascular surface area in normal nerves (34.9 ± 5.7%), autografts (29.5 ± 8.7%), allografts seeded with differentiated (38.9 ± 7.0%) and undifferentiated MSCs (29.2 ± 3.4%) did not significantly differ from each other. Unseeded allografts (21.2 ± 6.2%) had a significantly lower vascular surface area percentage than normal nonoperated nerves (13.7%, p = .001) and allografts seeded with differentiated MSCs (17.8%, p = .001). Although the vascular surface area was significantly correlated to the vascular volume (r = .416; p = .008), no significant differences were found between groups concerning vascular volumes. The vascularization pattern in allografts seeded with MSCs consisted of an extensive nonaligned network of microvessels with a centripetal pattern, while the vessels in autografts and normal nerves were more longitudinally aligned with longitudinal inosculation patterns. CONCLUSIONS: Neoangiogenesis of decellularized allograft nerves was enhanced by stem cell seeding, in particular by differentiated MSCs. The pattern of vascularization was different between decellularized allograft nerves seeded with MSCs compared to autograft nerves.

The rabbit brachial plexus as a model for nerve injury and repair Part 1: Anatomic study of the biceps and triceps innervation.

PURPOSE: Animal models can be helpful in evaluating new surgical strategies for brachial plexus reconstruction. While several groups have already used the rabbit brachial plexus to model injury, reports conflict in anatomic detail and do not identify a nerve-muscle pair to measure motor function recovery after reconstruction. The purpose of the current study is to describe the innervations of the biceps and triceps muscles in rabbits, which are both amenable to study in brachial plexus injury models. MATERIALS AND METHODS: Thirteen rabbits weighing 2-2.5 kg were anesthetized. Six rabbits were sacrificed and dissected using loupe and microscope magnification to understand the overall morphology of the brachial plexus. Seven rabbits underwent electrophysiologic investigation. A bipolar nerve stimulator was used to systematically stimulate the roots, trunks and divisions, and nerve branches of the rabbit brachial plexus and compound muscle action potential was used to record muscle response. Nerve length and width measurements were not recorded. RESULTS: Roots contributing to the brachial plexus were C5, C6, C7, C8, and T1. In contrast to other anatomical studies, T2 did not contribute to the brachial plexus. The triceps was innervated by the radial nerve, which received contributions from C6 (1.6 mA), C7 (1.9 mA), C8, and T1 (12.2 mA).The biceps had dual innervation (proximally and distally). The proximal branch received contributions from C6 (3.5 mA) and C7 (5mA). The distal portion was innervated by a branch from the median nerve, which received innervation from C6, C7, C8, and T1. CONCLUSIONS: The overall structure of rabbit brachial plexus is described and innervation of the biceps and triceps is described in detail. This anatomic investigation will form the basis of a future brachial plexus model of injury and repair.

Description and validation of a simple histological nerve tissue scoring system for nerve allografts.

BACKGROUND: In nerve allograft development, currently used subjective histological scoring systems to evaluate nerve structure in experimental studies are not uniform and have not been validated. The aim of this study was to describe and validate a simple, fast and inexpensive method to compare structural properties of nerve allografts on a histological level. MATERIALS AND METHODS: A total of 113 histological sections of rat (sciatic nerves) and human peripheral nerve segments (thoracodorsal and long thoracic nerve for motor and sural for sensory nerve) treated with various decellularization protocols were analyzed. Slides were stained with Hematoxylin & Eosin (H&E), Toluidine Blue and Laminin. A subjective scoring system using a 5-point scale was used to score each nerve section by four independent researchers. For validation of this score both inter- and intra-rater reliability were calculated using the Intraclass Correlation Coefficient (ICC). RESULTS: Overall, an excellent correlation between the different observers was found for the Toluidine Blue (ICC = 0.919, 95% CI: 0.891-0.941), H&E (ICC = 0.9, 95% CI: 0.865-0.927) and Laminin staining (ICC = 0.897, 95% CI: 0.860-0.926). Intra-rater reliability was good for all three staining techniques (ICC >0.8). CONCLUSION: This study demonstrates the validity of this simple scoring system to evaluate nerve structure after different processing protocols. All three evaluated staining techniques can reliably be used for both rat and human nerve tissue. We believe this method is suitable to compare different processing techniques to create processed nerve allografts, especially when the average scores of multiple raters are used.

Outcomes of Vascularized Bone Allotransplantation with Surgically Induced Autogenous Angiogenesis in a Large Animal Model: Bone Healing, Remodeling, and Material Properties.

BACKGROUND: Bone vascularized composite allotransplantation (VCA) is a possible alternative for the treatment of large bone defects. Clinical application of VCAs is limited by the need for life-long immunosuppression (IS). We report an alternative method to maintain bone allotransplant viability in a large animal model without the need for life-long IS by using autogenous vessel implantation. METHODS: Fourteen bone only VCAs were transplanted in a porcine tibia defect model with short-term IS. Two groups were used to evaluate the effect of the implantation of an autogenous arteriovenous (AV)-bundle, therefore the only difference between the groups was the patency of the AV-bundle. We radiographically evaluated bone healing and allogenic pedicle patency. AV-bundle patency and union were evaluated with micro-CT. Bone remodeling was assessed with histomorphometry and material properties were evaluated with axial compression testing and cyclic reference point indentation. RESULTS: Two subjects did not reach the final time point. Twelve tibiae healed proximally, and nine at the distal transplant-bone interface. Bone allotransplants showed their viability in the first 4 to 6 weeks by significant periosteal bridging arising from the transplant and maintained pedicle patency. Bone material properties were not affected by the implantation of an AV-bundle when compared with ligated AV-bundle controls, but diminished compared with normal bone. Significantly higher bone formation rates resulted from the implantation of a patent AV-bundle. CONCLUSION: New periosteal bone formation and subsequent bone healing result from blood flow through the microsurgically repaired nutrient blood supply, demonstrated by maintained allogenic pedicle patency. The implantation of a patent autogenous AV-bundle has no adverse effect on material properties, but a positive effect on bone remodeling of endosteal surfaces despite thrombosis of the allogenic pedicle. Bone material properties change after transplantation compared with normal bone, although 20-weeks survival time is relatively short for the final evaluation of bone material properties.

Overstuffing of Unstable Scaphoid Nonunions: A Radiographic Analysis of Carpal Parameters.

PURPOSE: The purpose of this study was to radiographically evaluate scaphoid length and carpal parameters before and after reconstruction of nonunions with interposition vascularized medial femoral condyle (MFC) bone graft to determine if the scaphoid was overstuffed or if normal anatomy was restored and to determine the effect on ulnar carpal translocation when the volar radiocarpal ligaments were left unrepaired. METHODS: Thirty-nine patients with established scaphoid nonunions with carpal collapse were reconstructed by interposition vascularized MFC bone grafts without repair of the volar radiocarpal ligaments. Pre- and postoperative radiographs and computed tomography scans of the 39 patients were reviewed. The scaphoid length, capitate-ulnar distance ratio (CUDR), modified carpal height ratio (MCHR), radiolunate (RL) and scapholunate (SL) angles were measured before and 3 months after surgery. Thirteen of these patients had contralateral wrist radiographs that were used for analysis of scaphoid length restoration. RESULTS: No significant changes were observed for CUDR and MCHR before and after surgery. The length of the scaphoid significantly improved after reconstruction from 21.9 ± 3.3 to 23.7 ± 3.4 mm on posteroanterior x-ray views and from 24.0 ± 2.2 to 27.7 ± 2.8 mm on lateral views. The RL and SL angles also changed significantly after surgery from 19.5° ± 13.5° to 4.1° ± 16.9° and from 67.5° ± 12.5° to 56.0° ± 12.5°, respectively. Regarding the 13 patients with contralateral x-rays, no differences were seen on CUDR, MCHR, or scaphoid length on posteroanterior x-ray views. However, the scaphoid length on lateral x-ray views increased from 23.1 ± 2.40 to 27.6 ± 2.78 mm and was significantly longer than the contralateral side by 9.6%. The RL and SL angles were restored and comparable with the contralateral side. CONCLUSIONS: The use of vascularized MFC bone graft increased scaphoid length by 9.6% and restored normal carpal alignment. Despite the increased scaphoid length compared with the contralateral side, the lack of repair of the volar radiocarpal ligaments did not cause ulnar carpal translocation in short-term follow-up. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Brachial plexus nerve injury and repair in a rabbit model part II: Does middle trunk injury result in loss of biceps function while repair results in recovery of biceps function.

INTRODUCTION: There is conflicting anatomic and innervation data regarding the rabbit brachial plexus injury model. This study aims to validate a rabbit brachial plexus injury model. We hypothesize the middle trunk (C6, C7) is the primary innervation of the biceps, and when cut and unrepaired, would demonstrate lack of recovery and when repaired would demonstrate evidence of recovery. MATERIALS AND METHODS: Twenty two male New Zealand white rabbits (3-4 kg) underwent unilateral surgical division of the middle trunk. Five rabbits were randomly assigned to the "no-repair" group while the remaining 17 rabbits underwent direct coaptation ("repair" group). Rabbits were followed for 12 weeks, with ultrasound measurement of biceps cross-sectional area performed preoperatively, and at 4, 8, and 12 weeks postoperatively. At a euthanasia procedure, bilateral compound muscle action potential (CMAP) and isometric tetanic force (ITF) were measured. Bilateral biceps muscles were harvested and wet muscle weight was recorded. The operative side was expressed as a percentage of the non-operated side, and differences between the no repair and repair rabbits were statistically compared. RESULTS: The repair group demonstrated significantly higher CMA (23.3 vs. 0%, p < .05), ITF (25.6 vs. 0%, p < .05), and wet muscle weight (65.8 vs. 52.0%, p < .05) as compared to the unrepaired group. At 4 weeks postoperatively, ultrasound-measured cross-sectional area of the biceps demonstrated atrophy in both groups. At 12 weeks, the repair group had a significantly larger cross-sectional area as compared to the no-repair group (89.1 vs. 59.3%, p < .05). CONCLUSIONS: This injury model demonstrated recovery with repair and lack of function without repair. Longer survival time is recommended for future investigations.

Bone vascularized composite allotransplantation model in swine tibial defect: Evaluation of surgical angiogenesis and transplant viability.

INTRODUCTION: In prior small animal studies, we maintained vascularized bone allotransplant viability without long-term immunotherapy. Instead, an autogenous neoangiogenic circulation is created from implanted vessels, sufficient to maintain bone viability with only 2 weeks immunosupression. Blood flow is maintained despite rejection of the allogeneic vascular pedicle thereafter. We have previously described a large animal (swine) pre-clinical model, reconstructing tibial defects with vascularized tibial allotransplants. In this manuscript, autologous angiogenesis is evaluated in this model and correlated with bone viability. MATERIALS AND METHODS: Allogeneic tibial segments were transplanted across a major swine leukocyte antigen mismatch. Microvascular repair of the bone VCA pedicle was combined with intraosseous implantation of an autogenous arteriovenous (AV) bundle. The bundle was ligated in group 1 (n = 4), and allowed to perfuse in group 2 (n = 4). Three-drug immunotherapy was given for 2 weeks. At 16 weeks micro-CT angiography quantified neoangiogenic vessel volume. Bone viability, rejection grade, and bone healing were analyzed. RESULTS: A substantial neoangiogenic circulation developed from the implanted AV-bundle in group 2, with vessel density superior to ligated AV-bundle controls (0.11 ± 0.05 vs. 0.01 ± 0.01, P = .029). Bone allotransplant viability was also significantly enhanced by neoangiogenesis (78.7 ± 4.4% vs. 27.7 ± 5.8%, P = .028) with higher bone healing scores (21.4 ± 2.9 vs. 12.5 ± 3.7, P = .029). Ligated control tibias demonstrated disorganized bone morphology and higher local inflammation (P = .143). CONCLUSION: Implantation of autogenous AV bundles into vascularized bone allotransplants resulted in the rapid formation of a neoangiogenic autogenous blood supply in a swine tibia model that maintained bone viability, improved bone healing, and minimized rejection.