Arthroscopic mobilization for metacarpophalangeal joint extension contracture.

BACKGROUND: As a first-line surgical treatment for treating metacarpophalangeal (MCP) joint extension contractures, mobilization surgery with open dorsal approach has been indicated. However, this procedure has the possibility to result in postoperative recurrence over the course of time because its invasive open dorsal approach has a negative impact on the postoperative gliding of the extensor mechanism. We report the preliminarily outcomes of patients who underwent a minimally invasive arthroscopic mobilization to alter and enhance their existing surgical strategy in place of MCP joint extension contractures. METHODS: This retrospective study included seven patients with 13 MCP joint extension contractures who had received an arthroscopic release of the bilateral collateral ligament and/or dorsal capsule of affected MCP joint. The extension contractures were caused by long-time immobilization with inadequate extended position of the MCP joint after either hand and wrist fractures, extensor tendon injury, or peripheral nerve palsy. All patients received sufficient exercise under the supervision of a physical therapist for more than 3 months before surgery. However, physical therapy did not improve the MCP joint extension contractures. We measured the active and passive flexion angles preoperatively at 1 and 6 months after surgery. The passive flexion angle was also measured after arthroscopic mobilization on the operation table. Surgery-related complications regarding nerve, vessel, skin, and tendon were also assessed. RESULTS: In all patients, significant improvements were observed in both the active and passive flexion angles 1 month after surgery, and continued to improve 6 months after surgery. Two out of 13 metacarpophalangeal joints developed blisters on the dorsal side of the joint, but conservatively recovered. CONCLUSIONS: Based on the positive improvements observed in our patients, we conclude that this minimally invasive arthroscopic technique has the potential to alter and enhance the surgical treatment strategy for MCP joint extension contractures.

Monitoring Vascular Compromise Using Ultrasound After Free Tissue Transfer.

OBJECTIVES: To report the clinical utility of high-resolution ultrasound (US) for monitoring vascular compromise after free tissue transfer. METHODS: Fifty-two tissue transfers in the extremities were included in this study. Blood flow around the anastomotic pedicle and subcutaneous tissue of the grafted flap was monitored with pulsed color and power Doppler US whenever the conventional monitoring method, comprising the bedside assessment of the temperature, capillary refill, and flap color, showed abnormalities until 1 week after reconstruction. RESULTS: All flaps were indicated for US monitoring, with 44 flaps showing Doppler signals in each position, even though conventional flap monitoring showed an abnormality. Forty of the 44 flaps showed no flap failure, whereas the remaining 4 flaps developed partial necrosis. Abnormal US findings were noted in 8 of the 52 flaps. Ultrasound revealed interruption of venous blood flow around the anastomotic pedicle in 6 of 8 flaps. Emergent exploration revealed venous occlusion at the anastomotic pedicle, similar to the US finding. In 2 of the 8 flaps, US showed no blood flow to either the anastomotic pedicle or subcutaneous tissue. Emergent exploration revealed arterial occlusion at the anastomotic pedicle. Seven of the 8 reexplored flaps were salvaged after revision surgery with complete flap survival. Partial flap survival was noted in 1 case, but complete flap failure was avoided. CONCLUSIONS: Ultrasound is a useful adjunct that enables a direct assessment of perfusion in grafted tissues, which may reduce unnecessary exploration when conventional flap monitoring shows an abnormality.

Macroscopic investigation of failed Kudo type 5 total elbow arthroplasty.

BACKGROUND: On the basis of the intra-articular findings during Kudo type 5 elbow prosthesis revision surgery, we infer the mechanisms leading to implant failure. MATERIALS AND METHODS: We performed primary Kudo type 5 total elbow arthroplasty on 60 rheumatoid elbows in 45 patients between 1994 and 2003. Revision surgery was performed in 8 patients (9 elbows) because of implant failure. We radiographically assessed their status before this surgical procedure and then assessed the surgical intra-articular findings based on surgery records and photographs. RESULTS: In all cases, revision surgery was necessitated by failure of the ulnar component. There were 2 types of implant failure: fracture of the ulnar component neck (n = 3) and loosening of the ulnar component (n = 6). In the latter group, 2 elbows exhibited valgus deformity of the retrieved ulnar component. There were no cases of metallosis or wear of the articular surface. CONCLUSION: This study describes the types of implant failure in unlinked Kudo type 5 total elbow arthroplasties with all-polyethylene ulnar components based on the intra-articular findings. Failure of the all-polyethylene ulnar component could have been caused by ulnar neck distortion that occurred prior to polyethylene wear on the joint surface. In addition, valgus stress on the elbow joint may have contributed to these implant failures.

Joint distraction and early mobilization using a new dynamic external finger fixator for the treatment of fracture-dislocations of the proximal interphalangeal joint.

BACKGROUND: Dynamic external fixation is a useful treatment option for unstable fracture-dislocations of the proximal interphalangeal (PIP) joint, because it simultaneously reduces axial pressure load on the joint surface, maintains congruent joint reduction, and permits early joint motion. However, most current devices are large, hindering finger movement, and unstable. To address these problems, we developed a dynamic external finger fixator, named the Micro Ortho Fixator®. The purpose of this study was to review the results of using the new external finger fixator to treat unstable fracture-dislocations of the PIP joint. MATERIALS AND METHODS: Nine patients who sustained unstable fracture-dislocation injuries of the PIP joint were treated with the Micro Ortho Fixator®. Seven fractures were accompanied by depressed bony fragments at the base of the middle phalanx. All patients were evaluated for pain and range of PIP motion at the final follow-up. Radiographs of the affected fingers were evaluated for PIP congruity and reduction. The mean follow-up duration was 11.1 months (range: 6-33 months). RESULTS: At the final follow-up, pain averaged 0.3 (range: 0-2) on the Numeric Pain Rating Scale, and the total arc of motion at the PIP joint averaged 91.2° (range: 50-110°). All fractures had healed, and the intra-articular step-off improved from 1.9 mm (SD: 1.0) before surgery to 0.2 mm (SD: 0.4) at the final follow-up. The patients who sustained sports injuries returned to competition after an average of 3.5 months (range: 2.5-4 months). CONCLUSION: The external fixator is compact and facilitates range-of-motion (ROM) exercises, has high stability, and achieves good joint congruity and an ROM equivalent to the healthy joint of the patient. STUDY DESIGN/LEVEL OF EVIDENCE: Therapeutic/IV.

Nerve regeneration in chitosan conduits and in autologous nerve grafts in healthy and in type 2 diabetic Goto-Kakizaki rats.

Knowledge about nerve regeneration after nerve injury and reconstruction in appropriate diabetic animal models is incomplete. Short-term nerve regeneration after reconstruction of a 10-mm sciatic nerve defect with either a hollow chitosan conduit or an autologous nerve graft was investigated in healthy Wistar and diabetic Goto-Kakizaki (GK) rats. After 21 days, axonal outgrowth, the presence of activated and apoptotic Schwann cells and the thickness of the formed matrix in the conduits were measured. In general, nerve regeneration was superior in autologous nerve grafts. In chitosan conduits, a matrix, which was thicker in diabetic rats, was formed and was positively correlated with length of axonal outgrowth. Axonal outgrowth in conduits and in nerve grafts extended further in diabetic rats than in healthy rats. There was a higher percentage of activating transcription factor 3 (ATF3)-immunostained cells in nerve segments from healthy rats than in diabetic rats after autologous nerve graft reconstruction. In chitosan conduits, more cleaved caspase 3-stained Schwann cells were generally observed in the matrix from the diabetic rats than in healthy rats. However, there were fewer apoptotic cells in the distal segment in diabetic rats reconstructed with a chitosan conduit. Preoperative glucose levels were positively correlated with axonal outgrowth after both reconstruction methods. Axonal regeneration was better in autologous nerve grafts than in hollow chitosan conduits and was enhanced in diabetic GK rats compared to healthy rats after reconstruction. This study provides insights into the nerve regeneration process in a clinically relevant diabetic animal model.

The neutralizing function of the anti-HTLV-1 antibody is essential in preventing in vivo transmission of HTLV-1 to human T cells in NOD-SCID/γcnull (NOG) mice.

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-1) causes both neoplastic and inflammatory diseases, including adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Because these life-threatening and disabling diseases are not yet curable, it is important to prevent new HTLV-1 infections. FINDINGS: In this study, we have established a simple humanized mouse model of HTLV-1 infection for evaluating prophylactic and therapeutic interventions. In this model, HTLV-1-negative normal human peripheral blood mononuclear cells (PBMCs) are transplanted directly into the spleens of severely immunodeficient NOD-SCID/γcnull (NOG) mice, together with mitomycin-treated HTLV-1-producing T cells. Using this model, we tested the efficacy of monoclonal antibodies (mAbs) specific to HTLV-1 as well as human IgG isolated from HAM/TSP patients (HAM-IgG) in preventing HTLV-1-infection. One hour before and 24 h after transplantation of the human cells, each antibody sample was inoculated intraperitoneally. On day 14, human PBMCs isolated from the mouse spleens were tested for HTLV-1 infection. Whereas fresh CD4-positive and CD8-positive T cells isolated from untreated mice or mice treated with isotype control mAb, HTLV-1 non-neutralizing mAbs to envelope gp46, gag p19, and normal human IgG were all infected with HTLV-1; the mice treated with either HTLV-1 neutralizing anti-gp46 mAb or HAM-IgG did not become infected. CONCLUSIONS: Our data indicate that the neutralizing function of the antibody, but not the antigen specificity, is essential for preventing the in vivo transmission of HTLV-1. The present animal model will also be useful for the in vivo evaluation of the efficacy of candidate molecules to be used as prophylactic and therapeutic intervention against HTLV-1 infection.

The first isolation of Clostridium massiliodielmoense from a dead beef cow in Japan and pitfalls to be aware of in identifying the Clostridium species.

Clostridium sp. was detected in the organs of a cow with black watery diarrhea in Japan. Results identifying this species were inconsistent; Clostridium novyi type A infection was suggested by PCR assay targeting Clostridium fliC region (fliC-multiplex PCR), while 16S rRNA gene sequencing identified the isolated bacteria as Clostridium massiliodielmoense. Sequencing of fliC-multiplex PCR products from the isolates revealed the presence of fliC region in C. massiliodielmoense, which had 92.7% nucleotide similarity to that of C. novyi type A JCM 1406T, leading to the false positive detection of C. novyi by the PCR. This is the first C. massiliodielmoense isolation from clinical specimens, suggesting the need for further research on its pathogenicity and improvement in fliC-multiplex PCR.

Association between three-dimensional motion analysis of the thumb and clinical parameters in patients with carpal tunnel syndrome.

We analysed the relationship between motor dysfunction of the thumb and the clinical parameters of carpal tunnel syndrome using three-dimensional motion analysis. This single-centred, prospective study included 65 hands in 51 patients with idiopathic carpal tunnel syndrome and 30 healthy hands. Three-dimensional thumb kinematics were acquired using a motion capture system with a retroreflective surface-based marker method. The trajectory area of thumb tip, adduction and abduction of the trapeziometacarpal joints and metacarpophalangeal joints were correlated with the clinical parameters. There was no significant correlation between the results of motion analysis values and patient-reported outcomes measures. Thumb movement disorder associated with carpal tunnel syndrome affected specific activities of daily living based on the pinching movements, such as 'writing' and 'buttoning clothes' among the patient-reported outcome measure items.Level of evidence: III.

On-Top Osteotomy of the Phalanx Base Combined With Modified Bilhaut: Cloquet Procedure for Atypical Radial Polydactyly.

In this report, we present the combination of on-top plasty with a modified Bilhaut-Cloquet procedure for treating atypical radial polydactyly with duplication at the metacarpophalangeal (MP) joint and triphalangism of the radial and ulnar phalanges, hypoplastic middle phalanx of the radial thumb, and hypoplastic phalanx base of the ulnar thumb. To preserve the stable MP and interphalangeal joints of the radial and ulnar thumbs, respectively, on-top plasty involved osteotomizing the middle phalanx and transferring the distal end of the middle phalanx of the ulnar finger to the phalanx base of the radial thumb. A modified Bilhaut-Cloquet procedure was used to combine the tips and nails of both thumbs. Twelve months postoperatively, good joint alignment and thumb tip appearance were achieved. On-top plasties effectively combined the desirable parts of both thumbs. The modified Bilhaut-Cloquet technique is particularly well-suited for atypical cases, such as the present case.

Three-dimensional motion analysis of pre- and postoperative thumb movement in trapeziometacarpal joint osteoarthritis-Comparison of arthrodesis and trapeziectomy with suspensionplasty.

Trapeziometacarpal osteoarthritis (TMC-OA) reduces the range of motion (ROM) of the thumb. However, the kinematic change achieved through surgical treatment remains unclear. Therefore, to quantify the kinematic change following TMC-OA surgery, we performed a three-dimensional motion analysis of the thumb using an optical motion capture system preoperatively and 1 year postoperatively in 23 patients with TMC-OA scheduled for arthrodesis (AD) or trapeziectomy with suspensionplasty (TS). Eighteen hands of nine healthy volunteers were also included as controls. Both procedures improved postoperative pain and Disability of the Arm, Shoulder and Hand scores, and AD increased pinch strength. The ROM of the base of the thumb was preserved in AD, which was thought to be due to the appearance of compensatory movements of adjacent joints even if the ROM of the TMC joint was lost. TS did not improve ROM. Quantifying thumb kinematic changes following TMC-OA surgery can improve our understanding of TMC-OA treatment and help select surgical procedures and postoperative assessment.

Natural OX40L expressed on human T cell leukemia virus type-I-immortalized T cell lines interferes with infection of activated peripheral blood mononuclear cells by CCR5-utilizing human immunodeficiency virus.

BACKGROUND: OX40 ligand (OX40L) co-stimulates and differentiates T cells via ligation of OX40 that is transiently induced on T cells upon activation, resulting in prolonged T cell survival and enhanced cytokine production by T cells. This view has led to the targeting of OX40 as a strategy to boost antigen specific T cells in the context of vaccination. In addition, the ligation of OX40 has also been shown to inhibit infection by CCR5-utilizing (R5) but not CXCR4-utilizing (X4) human immunodeficiency virus type-1 (HIV-1) via enhancement of production of CCR5-binding ß-chemokines. It was reasoned that human T cell leukemia virus type-I (HTLV-1) immortalized T cell lines that express high levels of OX40L could serve as an unique source of physiologically functional OX40L. The fact that HTLV-1+ T cell lines simultaneously also express high levels of OX40 suggested a potential limitation. RESULTS: Results of our studies showed that HTLV-1+ T cell lines bound exogenous OX40 but not OX40L, indicating that HTLV-1+ T cell lines express an active form of OX40L but an inactive form of OX40. Anti-OX40 non-blocking monoclonal antibody (mAb), but not blocking mAb, stained HTLV-1+ T cell lines, suggesting that the OX40 might be saturated with endogenous OX40L. Functionality of the OX40L was confirmed by the fact that a paraformaldehyde (PFA)-fixed HTLV-1+ T cell lines inhibited the infection of autologous activated peripheral blood mononuclear cells (PBMCs) with R5 HIV-1 which was reversed by either anti-OX40L blocking mAb or a mixture of neutralizing mAbs against CCR5-binding ß-chemokines. CONCLUSIONS: Altogether, these results demonstrated that autologous T cell lines immortalized by HTLV-1 can be utilized as a conventional source of physiologically functional OX40L.

Outcomes of Revision Unlinked Total Elbow Arthroplasty for Rheumatoid Elbow.

Background: Although unlinked total elbow arthroplasty (TEA) is a treatment option for end-stage rheumatoid arthritis (RA) of the elbow, its long-term outcomes were inferior. Moreover, revision TEA could be technically challenging. The unlinked TEA procedure comprises the ease of implant removal at revision and advantage of bone preservation. This study evaluated the clinical outcomes in patients who underwent revision TEA using primary unlinked TEA for rheumatoid elbows. It also aimed to determine whether selecting the unlinked prosthesis for the primary TEA would make revision more accessible and successful. Methods: We retrospectively reviewed data of 13 consecutive patients (14 elbows) who underwent revision TEAs for implant failure due to different aetiologies, excluding septic loosening. Three different unlinked TEA implants were used: the Kudo type-5 with all-polyethylene (AP) ulnar component, Kudo type-5 with metal-backed (MB) ulnar component and K-Now TEA. We evaluated the patients' pre- and postoperative outcomes, including the range of motion, pain score and Mayo Elbow Performance Index (MEPI). Results: Among the 14 elbows, 11 were revised using the Kudo type-5 ulnar component (nine and two with AP and MB ulnar component, respectively), and three using the K-Now. We found that each model of TEA had different tendencies to indication for revision surgery. Three more resulted in further failure. The clinical outcomes were assessed in the 11 surviving elbows. Eight of the 11 elbows showed no pain at the final follow-up. However, the remaining three showed only mild pain. The MEPI revealed that seven cases were excellent, two were good and two were fair. Conclusions: The mode of implant failure was largely dependent on the implant design. Furthermore, partial revision with the same implant design was sufficient in managing implant failure in the early phase. However, conversion from unlinked to linked design could be recommended in patients with progressive failure or instability. Level of Evidence: Level IV (Therapeutic).

Oxidation-treated carbon nanotube yarns accelerate neurite outgrowth and induce axonal regeneration in peripheral nerve defect.

Carbon nanotubes (CNTs) have the potential to promote peripheral nerve regeneration, although with limited capacity and foreign body reaction. This study investigated whether CNTs hydrophilized by oxidation can improve peripheral nerve regeneration and reduce foreign body reactions and inflammation. Three different artificial nerve conduit models were created using CNTs treated with ozone (O group), strong acid (SA group), and untreated (P group). They were implanted into a rat sciatic nerve defect model and evaluated after 8 and 16 weeks. At 16 weeks, the SA group showed significant recovery in functional and electrophysiological evaluations compared with the others. At 8 weeks, histological examination revealed a significant increase in the density of regenerated neurofilament and decreased foreign body giant cells in the SA group compared with the others. Oxidation-treated CNTs improved biocompatibility, induced nerve regeneration, and inhibited foreign-body reactions.

Bacille Calmette-Guérin Vaccine-Induced Tuberculous Elbow Osteomyelitis in an Infant: A Case Report.

CASE: We report a case of Bacillus Calmette-Guérin (BCG) vaccine-induced osteomyelitis of the distal end of the right humerus in a 1-year and 8-month-old girl. The patient was treated with debridement and a 12-month antituberculosis drug. After 3 years of follow-up, no growth disturbances or sequelae were observed. CONCLUSION: BCG osteomyelitis is difficult to diagnose because of its rarity. It is important to suspect BCG osteomyelitis based on symptoms and blood tests and to perform PCR testing. Long-term follow-up after treatment is necessary to monitor for recurrence and avoid growth disturbances until epiphyseal line closure occurs.

Dual Corrective Osteotomy of the Radius and Ulna for Mature Madelung Deformity Using CT-based 3D Simulation: A Case Report.

We report a patient with mature Madelung deformity who underwent radial and ulnar corrective osteotomy using three-dimensional (3D) simulation. An osteotomy model was created using the computer-aided design (CAD) software based on the computed tomography (CT) data. After correcting the ulna, the osteotomy angle of the radius was determined using the location of the lunate as a landmark in the 3D plane created by the longitudinal axis of the corrected ulna. Consequently, the ulna was flexed 3° and shortened by 5 mm, and the radius was extended at 36° and ulna deviated at 25° by open wedge osteotomy. The radial inclinations, volar tilt and ulnar variance were 25°, 45° and 5 mm preoperatively, and improved to 22°, 10° and 0 mm after surgery. At the 18-month follow-up, the patient reported no pain even during sports activity. The preoperative 3D simulation enabled precise preoperative planning and accurate correction of the Madelung deformity. Level of Evidence: Level V (Therapeutic).

Refracture of a Regenerated Hook of Hamate in a Professional Baseball Player: A Case Report.

Hook of hamate fracture occurs in baseball players during bat swing. These fractures are usually treated by excision of the fracture fragment and the players can return to the game without delay. We report a professional baseball player who presented with a hook of hamate fracture. He gave history of undergoing excision of the hook 4 years earlier for a fracture of the hook. He underwent re-excision of the regenerated hook and was asymptomatic at his final follow-up. Level of Evidence: Level V (Therapeutic).

Point-of-care ultrasound in musculoskeletal field.

The musculoskeletal field is relatively new in point-of-care ultrasound (POCUS), a modality that has been gaining significance with the evolution of ultrasound (US) equipment and high-frequency probes. Images have become progressively clearer over the past decade, making it possible to diagnose many pathological conditions without exposure to radiation. Ultrasonography reveals many soft tissue pathologies that cannot be visualized using plain radiographs, which have historically been the first choice for the evaluation of musculoskeletal disorders. US saves money and time compared to magnetic resonance imaging (MRI). Although it is difficult to diagnose a disorder inside bone, its surface can be visualized very clearly, and it is also possible to visualize cartilage. Furthermore, with POCUS, it is possible to confirm a disorder and the continuity of the fibrous structures of muscles, tendons, and ligaments. In addition, the understanding of pathological conditions of motor disturbances, such as nerve or muscle/tendon injury, nerve paralysis, adhesions of the tendons, and joint instability, is deepened by observing the movement of these structures. Peripheral nerves, even small branches, can be visualized, and pathological conditions can be pinpointed by observing the nerve morphology, continuity, and relationship with the surrounding tissues. Children can be examined in a safe, relaxed environment, without leaving their parents. In addition, US is significantly different from other modalities in that it can be used for both diagnosis and treatment. Being able to visualize target sites improves safety and route accuracy of needle insertion for injection or puncture. Musculoskeletal POCUS is indispensable in routine medical care and is a technique that medical residents should acquire.

Identification of an unique CXCR4 epitope whose ligation inhibits infection by both CXCR4 and CCR5 tropic human immunodeficiency type-I viruses.

BACKGROUND: Small chemical compounds which target chemokine receptors have been developed against human immunodeficiency virus type 1 (HIV-1) and are under investigation for use as anti-HIV-1 microbicides. In addition, monoclonal antibodies (mAbs) against chemokine receptors have also been shown to have anti-HIV-1 activities. The objective of the present study was to screen a panel of three anti-CXCR4 specific monoclonal antibodies (mAbs) for their ability to block the HIV-1 infection using in vitro activated primary peripheral blood mononuclear cells (PBMCs). RESULTS: PBMCs from normal donors were pre-activated with anti-CD3 and anti-CD28 mAbs for 1 day, and aliquots were infected with a low dose of CCR5-tropic (R5), CXCR4 tropic (X4) or dual tropic (X4R5) HIV-1 isolates and cultured in the presence of a panel of anti-CXCR4 mAbs. The panel included clones A145 mAb against the N-terminus, A120 mAb against a conformational epitope consisting of extracellular loops (ECL)1 and ECL2, and A80 mAb against ECL3 of CXCR4. Among these mAbs, the A120 mAb showed the most potent inhibition of infection, by not only X4 but surprisingly also R5 and X4R5 HIV-1. The inhibition of R5 HIV-1 was postulated to result from the novel ability of the A120 mAb to induce the levels of the CCR5-binding ß-chemokines MIP-1α, MIP-1ß and/or RANTES, and the down modulation of CCR5 expression on activated CD4+ T cells. Neutralizing anti-MIP-1α mAb significantly reversed the inhibitory effect of the A120 mAb on R5 HIV-1 infection. CONCLUSIONS: The data described herein have identified a unique epitope of CXCR4 whose ligation not only directly inhibits X4 HIV-1, but also indirectly inhibits R5 HIV-1 infection by inducing higher levels of natural CCR5 ligands.

Three-dimensional analysis of thumb motion recovery after carpal tunnel release.

This study quantified recovery of thumb motion in patients with carpal tunnel syndrome after carpal tunnel release using three-dimensional motion analysis with a retroreflective surface-based marker method. Eighteen hands from 14 patients who underwent carpal tunnel release for idiopathic carpal tunnel syndrome were included. The angular movements of the three joints of the thumb, the path length of the thumb tip and the area enclosed by the perimeter path of the thumb tip were measured during circumduction. The range of joint movement, including abduction/adduction of the trapeziometacarpal joint, and flexion/extension of the interphalangeal and metacarpophalangeal joints and the path length of the thumb tips, improved significantly 1 year after surgery. The quantification of thumb kinematics helps to better understand motor dysfunction in carpal tunnel syndrome, assess the severity of the condition and decide on treatment.Level of evidence: IV.

Carbon-nanotube yarns induce axonal regeneration in peripheral nerve defect.

Carbon nanotubes (CNTs) are cylindrical nanostructures and have unique properties, including flexibility, electrical conductivity, and biocompatibility. We focused on CNTs fabricated with the carbon nanotube yarns (cYarn) as a possible substrate promoting peripheral nerve regeneration with these properties. We bridged a 15 mm rat sciatic nerve defect with five different densities of cYarn. Eight weeks after the surgery, the regenerated axons crossing the CNTs, electromyographical findings, and muscle weight ratio of the lower leg showed recovery of the nerve function by interfacing with cYarn. Furthermore, the sciatic nerve functional index (SFI) at 16 weeks showed improvement in gait function. A 2% CNT density tended to be the most effective for nerve regeneration as measured by both histological axonal regeneration and motor function. We confirmed that CNT yarn promotes peripheral nerve regeneration by using it as a scaffold for repairing nerve defects. Our results support the future clinical application of CNTs for bridging nerve defects as an off-the-shelf material.