Toru Sunagawa

Three-dimensional CT imaging of flexor tendon ruptures in the hand and wrist

Objective The purpose of this study is to determine the applicability of 3D CT imaging in the evaluation of flexor tendon rupture in the hand and wrist. Design Twenty-four digits in 22 patients (18 adults, 4 children) with a spectrum of finger flexion disturbances were investigated by a multidetector-row CT scanner, and diagnosed by 3D CT image with the volume rendering technique. The accuracy of the image diagnosis was confirmed operatively in 20 digits. Results 3D CT imaging gave a precise analysis in all adult cases. It clearly depicted the location of rupture and tendon stump. All of the 12 digits diagnosed from the images as tendon rupture were operated on, and the operational finding correlated well with the diagnosis based on the image. In the children, the image analysis was equivocal. Conclusions 3D CT imaging can be useful when the diagnosis of flexor tendon rupture cannot be made based on trauma history and clinical examinations, and can be helpful in surgical planning.

Three-dimensional computed tomography imaging: its applicability in the evaluation of extensor tendons in the hand and wrist.

Objective: The purpose of this study was to determine whether 3-dimensional (3D) computed tomography (CT) imaging with volume rendering can accurately evaluate extensor tendons in the hand and wrist. Methods: Three-dimensional CT imaging was used to evaluate 14 cases. The location where the rupture was suspected was the wrist level in all cases. The accuracy of the image diagnosis was confirmed during surgery in 13 cases. Results: Three-dimensional CT could identify all extensor tendons proximal to the metacarpophalangeal joint. In the cases with rupture, the location of the distal stump could be identified, whereas that of the proximal stump was uncertain. The tendon stump location confirmed during surgery correlated well with the images. Conclusions: This study revealed the usefulness of 3D CT imaging in defining extensor tendons proximal to the metacarpophalangeal joint. This method increased the accuracy and ease of diagnosis and was always useful in surgical planning and patient education.

Platelet-rich plasma accelerated surgical angio-genesis in vascular-implanted necrotic bone: an experimental study in rabbits.

Background Platelets contain many kinds of growth factors with the ability to accelerate angiogenesis. We analyzed whether a single injection of platelet-rich plasma (PRP) would accelerate surgical angiogenesis in necrotic bone implanted with vascular tissue. Methods We used 24 Japanese White rabbits. PRP was refined from autologous blood by separation twice with centrifugation. A removed iliac bone was frozen in liquid nitrogen to ensure complete cellular necrosis. A narrow hole was made in the bone and the saphenous vascular bundle was passed through the hole. The bone was wrapped after injection of either 1 mL (1) PRP, or (2) saline solution into the hole, and was placed subcu-taneously in the thigh. In both groups, angiogenesis was compared 1 week and 2 weeks after surgery. Result Angiogenesis was observed along the implanted vascular bundle in both groups. At 1 and 2 weeks after surgery, both the vessel density and the average length of newly formed vessels of the experimental group were significantly greater than in the control group. Both the vessel density and the length were greater after 2 weeks than after 1 week. Interpretation A single injection of PRP accelerates surgical angiogenesis in vascular-implanted necrotic bone.

Regeneration of peripheral nerve after transplantation of CD133+ cells derived from human peripheral blood.

OBJECT Despite intensive efforts in the field of peripheral nerve injury and regeneration, it remains difficult to achieve full functional recovery in humans following extended peripheral nerve lesions. In this study, the authors examined the use of blood-derived CD133(+) cells in promoting the repair of peripheral nerve defects. METHODS The authors transplanted phosphate-buffered saline (control), mononuclear cells, or CD133(+) cells embedded in atelocollagen gel into a silicone tube that was used to bridge a 15-mm defect in the sciatic nerve of athymic rats (12 animals in each group). At 8 weeks postsurgery, molecular, histological, and functional evaluations were performed in regenerated tissues. RESULTS The authors found that sciatic nerves in which a defect had been made were structurally and functionally regenerated within 8 weeks after CD133(+) cell transplantation. From macroscopic evaluation, massive nervelike tissues were confirmed only in rats with CD133(+) cell transplantation compared with the other groups. Morphological regeneration in the samples after CD133(+) cell transplantation, as assessed using toluidine blue staining, was enhanced significantly in terms of the number of myelinated fibers, axon diameter, myelin thickness, and percentage of neural tissue. Compound muscle action potentials were observed only in CD133(+) cell-treated rats. Furthermore, it was demonstrated that the transplanted CD133(+) cells differentiated into Schwann cells by 8 weeks after transplantation. CONCLUSIONS The results show that CD133(+) cells have potential for enhancement of histological and functional recovery from peripheral nerve injury. This attractive cell source could be purified easily from peripheral blood and could be a feasible autologous candidate for peripheral nerve injuries in the clinical setting.

Human platelet-rich plasma promotes axon growth in brain-spinal cord coculture

Platelet-rich plasma (PRP) contains several growth factors, including platelet-derived growth factor (PDGF), transforming growth factor-&bgr;1 (TGF-&bgr;1), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF), that are associated with repair processes after central nervous system injury. Although PRP have been applied to some regenerative therapies, the regeneration effects of PRP on spinal cord injury have not been reported. This study applied a rat organ coculture system to examine the ability of PRP to enhance axonal growth in spinal cord tissues and to identify the growth factors in PRP that contribute to the regulation of axon growth. PRP from human peripheral blood was added to organ cocultures. Furthermore, neutralizing antibodies against PDGF-AB, TGF-&bgr;1, IGF-1, or VEGF were added to the cocultures with PRP. Axon growth from the brain cortex into the spinal cord was assessed quantitatively using anterograde axon tracing with DiI. Addition of PRP to the cocultures promoted axon growth, and the axon growth was significantly suppressed by the addition of neutralizing antibodies against IGF-1 and VEGF, but not PDGF-AB. In contrast, axon growth was promoted significantly by the addition of neutralizing antibodies against TGF-&bgr;1. These findings indicate that PRP promotes axon growth in spinal cord tissues through mechanisms associated with IGF-1 and VEGF, and that TGF-&bgr;1 in PRP exerts negative effects on axon growth.

Pollicization of the index finger for traumatic thumb amputation.

Background: Indications for pollicization of the index finger have decreased since the toe-to-thumb transfer and wraparound flap have been developed for thumb reconstruction. Pollicization, however, remains a useful method of thumb reconstruction depending on the amputation level, age, and patients’ requests. The purpose of this study was to evaluate the authors’ results and to clarify indications for pollicization. Methods: Eight patients treated by pollicization of the index finger after thumb amputation were reviewed retrospectively. Five men and three women were included. The age at surgery ranged from 24 to 66 years, with a mean age of 43 years. Amputation levels included the metacarpophalangeal joint in four patients, the first metacarpal in three, and the carpometacarpal joint in one. The period between injury and pollicization ranged from 0 days to 4 years. Postoperative evaluations included thumb range of motion, opposition and pinch function, grasp and pinch strength, sensation, conversion of position sense, a “picking-up” test, and appearance. Results: The follow-up period ranged from 5 to 28 years, with an average of 15 years, excluding one patient who died during the follow-up period. The thenar muscles were retained in four patients, who had excellent postoperative function and satisfactory results. Conclusions: Pollicization gives excellent results if the thenar muscles can be retained; opposition can be expected after this procedure. However, if the thenar muscles cannot be preserved, the reconstructed thumb may function as a post against the fingers to regain grasping and pinching functions.

Fate of donor cells in vascularized bone grafts: Identification of systemic chimerism by the polymerase chain reaction

Systemic chimerism, or the movement of cells from a transplanted tissue into host organs, is a phenomenon known to occur in association with development of immunological tolerance in allotransplantation. However, little is known about the fate and movement of cells into or out of autogenous free tissue transfers, including vascularized bone grafts. The purpose of this study was to identify systemic chimerism in vascularized bone grafts by transplantation of a vascularized tibiofibular graft from isogenous (inbred) male Lewis rats to female recipients. Donor (male) cells could be identified in the recipient (female) tissues by semiquantitative polymerase chain reaction analysis for a Y chromosome-specific DNA sequence. Chimerism was assessed at 1, 12, 18, and 24 weeks after transplantation. Competitive polymerase chain reaction study using the specific primers for a Y-chromosome marker ( gene) and an autosomal gene (GAPDH) allowed detection of small amounts of male cells in a large pool of female cells and measurement of their relative proportions as a function of time. Of 19 nonimmunosuppressed recipients, nine animals (47 percent) showed low-level chimerism (<0.1 percent) in the peripheral blood. Nine (47 percent), three (16 percent), and two (11 percent) recipients showed high-level chimerism (>1 percent) in the spleen, liver, and thymus, respectively, at final assessment. Donor cells were detected in all bone grafts and in six contralateral tibial bones (i.e., 67 percent of sampled contralateral tibial bones) at 18 and 24 weeks after transplantation. Twenty-four recipients were immunosuppressed with FK506 (tacrolimus) to suppress reaction to a minor histocompatibility barrier present on the Y chromosome. In this group, 14 animals (58 percent) showed low-level chimerism in peripheral blood and 12 (50 percent), eight (33 percent), and one (4 percent) recipients showed high-level chimerism in the spleen, thymus, and liver, respectively. Transplanted cells were detected in nine contralateral tibial bones (i.e., 60 percent of sampled contralateral tibial bones) at 12 and 18 weeks after surgery. The results indicate that polymerase chain reaction for the Y chromosome is a useful tool for differentiating between donor and recipient cell populations experimentally using sex-mismatched tissues in a rat model. This study demonstrated that systemic chimerism occurs after successful vascularized bone transplantation. Transplanted cells not only survive in the graft but also gradually migrate into the recipients body.

Administration of microRNA-210 promotes spinal cord regeneration in mice.

Study Design. Experimental animal study of treatment of spinal cord injury (SCI). Objective. To investigate the therapeutic effects of administering microRNA-210 (miR-210) to promote angiogenesis in a mouse SCI model. Summary of Background Data. Despite many previous studies regarding SCI, there is no established treatment in clinical practice. miRNAs have attracted immense attention because of their crucial role in human disease, and they have been proposed as potential new therapeutic targets for SCI. Methods. At specific times after administration, mice were analyzed by several methods to examine the distribution of miR-210, histological angiogenesis and neurogenesis, functional recovery from SCI, and the expression levels of target genes of miR-210. Results. After injection of miR-210 into the lesion of the injured spinal cord, expression of endogenous miR-210 increased until 6 days after injection. The administration of miR-210 promoted angiogenesis and astrogliosis, and improved functional recovery after SCI compared with the noninjected controls. Furthermore, the area made up of axons and myelin in the spinal cord tissues caudal to the injury site was larger in mice injected with miR-210 than those of the controls. Apoptotic cell death was lower in mice administered miR-210. After administration of miR-210, the expressions of protein-tyrosine phosphate 1B and ephrin-A3, both gene targets of miR-210, were downregulated at the protein level and protein-tyrosine phosphate 1B expression was also downregulated at the transcriptional level. Conclusion. MiR-210 might contribute to spinal cord repair by promoting angiogenesis via the inhibition of protein-tyrosine phosphate 1B and ephrin-A3. Level of Evidence: N/A

HIGH-RESOLUTION ULTRASONOGRAPHIC EVALUATION OF ''HOURGLASS-LIKE FASCICULAR CONSTRICTION'' IN PERIPHERAL NERVES: A PRELIMINARY REPORT

An hourglass-like constriction is a focal fascicular lesion observed in one or a few places in one or a few fascicles of a peripheral nerve trunk, and usually affects the anterior interosseous (AIN) or posterior interosseous (PIN) nerve. Constrictions have previously been discovered only by surgical exploration, and have been unable to be recognized on pre-operative imaging. We encountered some cases in which the lesion was able to be diagnosed pre-operatively by high-resolution ultrasonography; these findings were then confirmed intra-operatively. Five consecutive cases were included in this study. In three cases with constrictions revealed on pre-operative ultrasound, the findings were confirmed intra-operatively. In the remaining two cases in which no constrictions were detected pre-operatively, no constriction was revealed intra-operatively. High-resolution ultrasonography may play a significant role in the diagnosis of hourglass-like constrictions, and may thus lead to significant changes in treatment strategies for AIN and PIN palsy.

Short Interposed Pedicle of Flow-Through Anterolateral Thigh Flap for Reliable Reconstruction of Damaged Upper Extremity

In microvascular reconstructive surgery, the recipient vessel in free flap transfer is often sacrificed to provide the vascular pedicle anastomosis. As the recipient vessel is likely to be necessary for distal circulation in the damaged upper extremity, preserving its patency is critical. Flow-through anastomosis is one method that preserves the recipient vessels patency. We present here eight patients who underwent upper-extremity reconstructions with a free flow-through anterolateral thigh flap. The flaps short vascular pedicle was interposed into a division of the radial artery and anastomosed on both sides of the pedicles T-shaped arterial segment. The flow-through flap has various advantages, not only making it possible to reconstruct both vessels and soft tissues but also preserving recipient vessels and balancing the blood supply or pressure in the flap. In clinical situations that do not require reconstruction of the artery, the short interposed pedicle of the free anterolateral thigh flow-through flap offers a versatile and reliable option for microsurgical reconstruction of defects in the upper extremities.