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.

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.

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).

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).

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).

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.

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.

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.

Treatment of Intra-Articular Distal Phalanx Fractures in Baseball Players by Joint Distraction and Early Mobilization Using a New Dynamic External Finger Fixator.

In baseball players, a high degree of functional recovery is required for the treatment of fractures in the distal interphalangeal (DIP) joint, especially on the throwing side. While dynamic external fixation is a useful treatment option to restore the joint function, existing external fixators are too large for use on DIP joints. Three cases of DIP joint intra-articular comminuted fractures in baseball players treated using the new dynamic external finger fixator which we developed are reported. The external fixator was kept attached for four weeks. The patients returned to play baseball 7-8 weeks after surgery. The total arc of the DIP joint was 90-100% of the contralateral side. Follow-up radiographs demonstrated that joint congruity had been reacquired. This technique was adaptive in the treatment of comminuted intra-articular fractures of the DIP joint and resulted in a near-normal range of joint motion and remodeling of the joint surface.

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.

Plantar Partial Pressure Analysis in a Patient with Reverse Extensor Digitorum Brevis Flap for the Treatment of Hallux Injury.

INTRODUCTION: An extensor digitorum brevis (EDB) flap can be used to cover a small soft-tissue defect and has been widely used as pedicled flap to cover defects around the ankle and foot. However, its post-operative functional recovery is unknown. Few reports have evaluated gait after foot flap surgeries, although gait assessment is considered to be necessary for functional evaluation after foot reconstruction. We performed a reverse EDB flap to treat a right hallux injury and conducted a plantar partial pressure (PPP) analysis as a postoperative functional evaluation. CASE REPORT: A 30-year-old laborer suffered an injury resulting in necrosis of the distal phalanx and soft-tissue defect of the proximal phalanx. After amputation, the proximal phalanx was covered with a reverse EDB flap. PPP analysis involved a 4-m-long platform system (P-Walk) and was conducted 3- and 12-month post-surgery. Walking velocity and the single-support phase on the affected limb had increased markedly after 12 months. After 12 months, the PPP of the first metatarsal head was greater than on the unaffected side, and the cadence and single-leg support rate were equal to the unaffected side. CONCLUSION: A nearly normal gait was obtained by covering the basal part of the hallux with an EDB flap and preserving the metatarsophalangeal joint.

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.

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.

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.

Elimination of human T cell leukemia virus type-1-infected cells by neutralizing and antibody-dependent cellular cytotoxicity-inducing antibodies against human t cell leukemia virus type-1 envelope gp46.

Human T cell leukemia virus type-1 (HTLV-1) is prevalent worldwide with foci of high prevalence. However, to date no effective vaccine or drug against HTLV-1 infection has been developed. In efforts to define the role of antibodies in the control of HTLV-1 infection, we capitalized on the use of our previously defined anti-gp46 neutralizing monoclonal antibody (mAb) (clone LAT-27) and high titers of human anti-HTLV-1 IgG purified from HAM/TSP patients (HAM-IgG). LAT-27 and HAM-IgG completely blocked syncytium formation and T cell immortalization mediated by HTLV-1 in vitro. The addition of these antibodies to cultures of CD8(+) T cell-depleted peripheral blood mononuclear cells (PBMCs) from HAM/TSP patients at the initiation of culture not only decreased the numbers of Tax-expressing cells and the production of HTLV-1 p24 but also inhibited the spontaneous immortalization of T cells. Coculture of in vitro-HTLV-1-immortalized T cell lines with autologous PBMCs in the presence of LAT-27 or HAM-IgG, but not an F(ab')2 fragment of LAT-27 or nonneutralizing anti-gp46 mAbs, resulted in depletion of HTLV-1-infected cells. A 24-h (51)Cr release assay showed the presence of significant antibody-dependent cellular cytotoxicity (ADCC) activity in LAT-27 and HAM-IgG, but not F(ab')2 of LAT-27, resulting in the depletion of HTLV-1-infected T cells by autologous PBMCs. The depletion of natural killer (NK) cells from the effector PBMCs reduced this ADCC activity. Altogether, the present data demonstrate that the neutralizing and ADCC-inducing activities of anti-HTLV-1 antibodies are capable of reducing infection and eliminating HTLV-1-infected cells in the presence of autologous PBMCs.

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.

A novel and simple method for generation of human dendritic cells from unfractionated peripheral blood mononuclear cells within 2 days: its application for induction of HIV-1-reactive CD4(+) T cells in the hu-PBL SCID mice.

Because dendritic cells (DCs) play a critical role in the regulation of adaptive immune responses, they have been ideal candidates for cell-based immunotherapy of cancers and infections in humans. Generally, monocyte-derived DCs (MDDCs) were generated from purified monocytes by multiple steps of time-consuming physical manipulations for an extended period cultivation. In this study, we developed a novel, simple and rapid method for the generation of type-1 helper T cell (Th1)-stimulating human DCs directly from bulk peripheral blood mononuclear cells (PBMCs). PBMCs were cultivated in the presence of 20 ng/ml of granulocyte-macrophage colony-stimulating factor, 20 ng/ml of interleukin-4 (IL-4) and 1,000 U/ml of interferon-ß for 24 h followed by 24 h maturation with a cytokine cocktail containing 10 ng/ml of tumor necrosis factor-α (TNF-α), 10 ng/ml of IL-1ß and 1 µg/ml of prostaglandin E2. The phenotype and biological activity of these new DCs for induction of allogeneic T cell proliferation and cytokine production were comparable to those of the MDDCs. Importantly, these new DCs pulsed with inactivated HIV-1 could generated HIV-1-reactive CD4(+) T cell responses in humanized mice reconstituted with autologous PBMCs from HIV-1-negative donors. This simple and quick method for generation of functional DCs will be useful for future studies on DC-mediated immunotherapies.

In vivo bioluminescence imaging of magnetically targeted bone marrow-derived mesenchymal stem cells in skeletal muscle injury model.

The purpose of this study is to clarify the kinetics of transplanted mesenchymal stem cells (MSCs) in rat skeletal muscle injury model and the contribution of the magnetic cell delivery system to muscle injury repair. A magnetic field generator was used to apply an external magnetic force to the injury site of the tibia anterior muscle, and 1 × 10(6) MSCs labeled with ferucarbotran-protamine complexes, which were isolated from luciferase transgenic rats, were injected into the injury site. MSCs were injected with and without an external magnetic force (MSC M+ and MSC M- groups, respectively), and phosphate-buffered saline was injected into injury sites as a control. In vivo bioluminescence imaging was performed immediately after the transplantation and, at 12, 24, and 72 h, and 1 and 4 weeks post-transplantation. Also, muscle regeneration and function were histologically and electromechanically evaluated. In vivo bioluminescence imaging showed that the photon of the MSC M+ group was significantly higher than that of the MSC M- group throughout the observation period. In addition, muscle regeneration and function in the MSC M+ group was histologically and functionally better than that of the MSC M- group. The results of our study indicated that magnetic cell delivery system may be of use in directing the transplanted MSCs to the injury site to promote skeletal muscle regeneration.

The effect of intra-articular injection of microRNA-210 on ligament healing in a rat model.

BACKGROUND: It is known from clinical and experimental studies that the healing potential of the anterior cruciate ligament (ACL) is extremely poor and that early phases of ligament healing require an augmented blood supply. MicroRNA (miRNA) is a type of small, noncoding RNA that negatively regulates gene expression, and miRNA (miR)-210 is reported to be crucial for cell response to hypoxia, vascular endothelial growth factor (VEGF)-driven endothelial cell migration, and formation of capillary-like structures. PURPOSE: The purpose of this study was to examine the effect of intra-articular injection of miRNA miR-210 on acceleration of ACL healing. STUDY DESIGN: Controlled laboratory study. METHODS: Two experiments were performed in this study. The ACLs of 12-week-old male LEW/CrlCrlj rats were partially transected. First, the temporal expression change of miR-210 after ACL injury was analyzed using real-time polymerase chain reaction (PCR) on day zero, and 1, 2, and 4 weeks after injury (n = 5 at each time point). Next, intra-articular injection of double-stranded (ds) miR-210 with atelocollagen was performed soon after injury. The control group was injected with control small interfering RNA (siRNA). Four weeks after injection, biomechanical and histological assessments of samples stained with H&E as well as Masson trichrome, and immunohistochemistry for VEGF, fibroblast growth factor 2 (FGF2), isolectin B4, and collagen type I, were performed. Real-time PCR analysis was also performed for quantitative evaluation of miR-210, VEGF-A, and collagen type I. RESULTS: Real-time PCR analysis revealed that miR-210 expression was decreased soon after injury but gradually increased thereafter. Histological analysis confirmed that the transected area was covered with healing tissue in the miR-210 group but remained devoid of any tissue in the control group 4 weeks after injury. Biomechanical analysis confirmed the improvement of biomechanical properties in the miR-210 group; the ultimate failure loads 4 weeks after injection were 30.5 ± 3.1 N in the miR-210 group and 22.8 ± 3.1 N in the control group (P < .05). Real-time PCR analysis showed that endogenous miR-210, VEGF, and collagen type I were highly expressed compared with controls, and immunohistochemistry for VEGF, FGF2, isolectin B4, and collagen type I showed that VEGF and FGF2 were highly upregulated, and there were abundant blood vessels and fibrotic deposition in the miR-210 group. CONCLUSION: Injection of ds miR-210 was effective in promoting the healing of partially torn ACLs through enhancement of angiogenesis via upregulation of VEGF and FGF2. CLINICAL RELEVANCE: It might represent a potential therapeutic approach for treatment of ACL injury.