Delivery of nitric oxide-releasing silica nanoparticles for in vivo revascularization and functional recovery after acute peripheral nerve crush injury.

Nitric oxide (NO) has been shown to promote revascularization and nerve regeneration after peripheral nerve injury. However, in vivo application of NO remains challenging due to the lack of stable carrier materials capable of storing large amounts of NO molecules and releasing them on a clinically meaningful time scale. Recently, a silica nanoparticle system capable of reversible NO storage and release at a controlled and sustained rate was introduced. In this study, NO-releasing silica nanoparticles (NO-SNs) were delivered to the peripheral nerves in rats after acute crush injury, mixed with natural hydrogel, to ensure the effective application of NO to the lesion. Microangiography using a polymer dye and immunohistochemical staining for the detection of CD34 (a marker for revascularization) results showed that NO-releasing silica nanoparticles increased revascularization at the crush site of the sciatic nerve. The sciatic functional index revealed that there was a significant improvement in sciatic nerve function in NO-treated animals. Histological and anatomical analyses showed that the number of myelinated axons in the crushed sciatic nerve and wet muscle weight excised from NO-treated rats were increased. Moreover, muscle function recovery was improved in rats treated with NO-SNs. Taken together, our results suggest that NO delivered to the injured sciatic nerve triggers enhanced revascularization at the lesion in the early phase after crushing injury, thereby promoting axonal regeneration and improving functional recovery.

A Case of Disseminated Herpes Zoster Presenting as Vesicles Limited to Skin Lesions with Lymphoma Cutis Involvement.

After primary infection, varicella zoster virus (VZV) causes prolonged latent infections that may reactivate, depending on the immunologic status of the host. We present a case of VZV reactivation in a 10-year-old male patient that underwent unrelated peripheral blood stem cell transplantation (uPBSCT) for T-lymphoblastic lymphoma with lymphoma cutis lesions. This patient had a history of herpes zoster involving the right L2-5 dermatome and trigeminal V1 dermatome prior to uPBSCT. Three months post-uPBSCT, the patient's underlying disease relapsed, and the patient presented with lymphoma cutis lesions. A few days after a skin biopsy was performed to pathologically confirm skin relapse, vesicles appeared only involving the skin areas with lymphoma cutis. This case illustrates how decreased areas of epidermal immune mechanisms may cause atypical presentations of varicella infection.

Comparison of two different decellularization methods for processed nerve allograft.

The use of processed nerve allografts as an alternative to autologous nerve grafts, the gold standard treatment for peripheral nerve defects, is increasing. However, it is not widely used in Korea due to cost and insurance issues. Moreover, the main detergent used in the conventional Hudson method is unavailable. Therefore, a new nerve allograft decellularization process is needed. We aimed to compare the traditional Hudson method with a novel decellularization process that may remove cellular content more efficiently while preserving the extracellular matrix (ECM) structure using low concentration sodium dodecyl sulfate (SDS) and nuclease. After each decellularization process, DNA content was measured in nerve tissue. Masson's trichrome staining and scanning electron microscopy were performed to determine the state of preservation of the ECM. A significantly greater amount of DNA content was removed in the novel method, and the ECM structure was preserved in both methods. For the in vivo study, a 15-mm long sciatic nerve defect was created in two groups of Sprague-Dawley rats, and processed nerve allografts decellularized using the Hudson or novel method were transplanted. Functional and histological recovery results were measured 12 weeks post-transplantation. Ankle contracture angle, maximal isometric tetanic force of the tibialis anterior (TA), and the TA mass were compared between the groups, as well as the percent neural tissue (100 × neural area/intrafascicular area). There was no significant difference in functional and histological nerve recovery between the methods. The novel method is appropriate for developing a processed nerve allograft.

The Combined Procedure of Ulnar Metaphyseal Shortening Osteotomy With Triangular Fibrocartilage Complex Foveal Knotless Repair.

Ulnar impaction syndrome (UIS) and triangular fibrocartilage complex (TFCC) tear are common causes of ulnar-sided wrist pain. As a standard surgical treatment, ulnar-shortening osteotomy (USO) and TFCC repair are used respectively. Patient spectrums of UIS accompanied by distal radioulnar joint instability or traumatic TFCC foveal tear with UIS symptoms exist, and both USO and TFCC repair are necessary for treating some of these patients. However, there have been few reports on the procedure for performing these 2 operations concurrently. We introduce a combined procedure to concurrently perform USO and TFCC repair. We performed a USO in the ulnar metaphysis using a locking plate and open TFCC knotless repair using a suture anchor at the ulnar fovea. In this technique, USO is conducted in the metaphysis, which is favorable to union, using a small plate that is easy to handle, and knotless TFCC repair can be performed simultaneously through a single small incision.

The anatomy of the saphenous and sural nerves as a source of processed nerve allografts.

As an alternative to autologous nerve donors, acellular nerve allografts (ANAs) have been studied in many experiments. There have been numerous studies on processing ANAs and various studies on the clinical applications of ANA, but there have not been many studies on sources of ANAs. The purposes of the present study were to evaluate the course of the saphenous and sural nerves in human cadavers and help harvest auto- or allografts for clinical implications. Eighteen lower extremities of 16 fresh cadavers were dissected. For the saphenous nerve and sural nerve, the distances between each branch and the diameters at the midpoint between each branch were measured. In the saphenous nerve, the mean length between each branch ranged from 7.2 to 28.6 cm, and the midpoint diameter ranged from 1.4 to 3.2 mm. In the sural nerve, the mean length between each branch ranged from 17.4 to 21 cm, and the midpoint diameter ranged from 2.3 to 2.8 mm. The present study demonstrates the length of the saphenous and sural nerve without branches with diameters larger than 1 mm. With regard for the clinical implications of allografts, the harvest of a selective nerve length with a large enough diameter could be possible based on the data presented in the present study.

Comparison of the regeneration induced by acellular nerve allografts processed with or without chondroitinase in a rat model.

There have been various studies about the acellular nerve allograft (ANA) as the alternative of autologous nerve graft in the treatment of peripheral nerve defects. As well as the decellularization process methods of ANA, the various enhancement methods of regeneration of the grafted ANA were investigated. The chondroitin sulfate proteoglycans (CSPGs) inhibit the action of laminin which is important for nerve regeneration in the extracellular matrix of nerve. Chondroitinase ABC (ChABC) has been reported that it enhances the nerve regeneration by degradation of CSPGs. The present study compared the regeneration of ANA between the processed without ChABC group and the processed with ChABC group in a rat sciatic nerve 15 mm gap model. At 12 weeks postoperatively, there was not a significant difference in the histomorphometric analysis. In the functional analysis, there were no significant differences in maximum isometric tetanic force, wet muscle weight of tibialis anterior. The processed without ChABC group had better result in ankle contracture angle significantly. In conclusion, there were no significant differences in the regeneration of ANA between the processed without ChABC group and the processed with ChABC group.

Changes in Ulnar Variance after a Triangular Fibrocartilage Complex Tear.

Purpose The relationship between triangular fibrocartilage complex (TFCC) tear and ulnar impaction syndrome has not been fully understood. We hypothesized that a TFCC tear could change the ulnar variance, which may be the cause of ulnar impaction syndrome. Patients and Methods A total of 72 patients who underwent TFCC foveal repair between January 2011 and June 2016 were included in this retrospective study. Among them, 44 patients diagnosed with TFCC foveal tear with distal radioulnar joint instability and no ulnar impaction syndrome underwent TFCC foveal repair only (group A) and 28 patients diagnosed with TFCC foveal tear with ulnar impaction syndrome underwent TFCC foveal repair and ulnar shortening osteotomy simultaneously (group B). We measured their ulnar variances in preoperative, postoperative, and last follow-up plain radiography. We also compared them with the ulnar variance of the contralateral (uninjured) wrist. Postoperative clinical outcomes, such as range of motions of the wrist, the visual analog scale (VAS) for pain, grip strength, and Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, were assessed. Results Ulnar variance increased after TFCC tears compared with that on the uninjured side in both groups (group A: 0.98 vs. 0.52 mm, p = 0.013; group B: 2.71 vs. 2.13 mm, p = 0.001). Once the TFCC was repaired, ulnar variance decreased (group A: 0.98 to 0.01 mm, p < 0.01; group B: 2.71 to 0.64 mm, p < 0.01). However, it was increased on the last follow-up radiograph (group A: 0.01 to 0.81 mm, p < 0.01; group B: 0.64 to 1.05 mm, p = 0.004). There were no significant improvement of range of motion, except for pronation-supination motion ( p = 0.04). Mean grip strength increased from 56.8 to 70.8% of the contralateral unaffected hand at the last assessment ( p = 0.01). Mean VAS for pain decreased from 7.4 ± 2.5 preoperatively to 2.7 ± 2 postoperatively ( p = 0.001). The QuickDASH score significantly improved from 45 to 9 ( p = 0.001). Conclusion Ulnar variance may be changed after a TFCC tear. In our study, it decreased after TFCC foveal repair. However, as time went on, the ulnar variance increased again, which could be one of the causes of ulnar impaction syndrome and ulnar-sided wrist pain. Level of Evidence This is a therapeutic Level IV study.

Pearls and Pitfalls of the Volar Locking Plating for Distal Radius Fractures.

Volar locking plate fixation has been widely accepted method for the treatment of unstable distal radius fractures. Although the results of volar locking plate fixation are encouraging, it may cause implant-related complications such as flexor or extensor tendon injuries. In depth understanding of anatomy of the distal radius is mandatory in order to obtain adequate fixation of the fracture fragments and to avoid these complications. This article will review the anatomic characteristics of the distal radius because selecting proper implant and positioning of the plate is closely related to the volar surface anatomy of the distal radius. The number and the length of distal locking screws are also important to provide adequate fixation strength to maintain fracture fixation. We will discuss the pros and cons of the variable-angle locking plate, which was introduced in an effort to provide surgeons with more freedom for fixation. Finally, we will discuss about correcting radial length and volar tilt by using eccentric drill holes and distal locking first technique.

The influence of vascularization of transplanted processed allograft nerve on return of motor function in rats.

Processed nerve allografts have become an alternative to repair segmental nerve defects, with results comparable with autografts regarding sensory recovery; however, they have failed to reproduce comparable motor recovery. The purpose of this study was to determine how revascularizaton of processed nerve allograft would affect motor recovery. Eighty-eight rats were divided in four groups of 22 animals each. A unilateral 10-mm sciatic nerve defect was repaired with allograft (group I), allograft wrapped with silicone conduit (group II), allograft augmented with vascular endothelial growth factor (group III), or autograft (group IV). Eight animals from each group were sacrificed at 3 days, and the remaining animals at 16 weeks. Revascularization was evaluated by measuring the graft capillary density at 3 days and 16 weeks. Measurements of ankle contracture, compound muscle action potential, tibialis anterior muscle weight and force, and nerve histomorphometry were performed at 16 weeks. All results were normalized to the contralateral side. The results of capillary density at 3 days were 0.99% ± 1.3% for group I, 0.33% ± 0.6% for group II, 0.05% ± 0.1% for group III, and 75.6% ± 45.7% for group IV. At 16 weeks, the results were 69.9% ± 22.4% for group I, 37.0% ± 16.6% for group II, 84.6% ± 46.6% for group III, and 108.3% ± 46.8% for group IV. The results of muscle force were 47.5% ± 14.4% for group I, 21.7% ± 13.5% for group II, 47.1% ± 7.9% for group III, and 54.4% ± 10.6% for group IV. The use of vascular endothelial growth factor in the fashion used in this study improved neither the nerve allograft short-term revascularization nor the functional motor recovery after 16 weeks. Blocking allograft vascularization from surrounding tissues was detrimental for motor recovery. The processed nerve allografts used in this study showed similar functional motor recovery compared with that of the autograft.

Effect of Vascular Endothelial Growth Factor Administration on Nerve Regeneration after Autologous Nerve Grafting.

BACKGROUND: The aim of this study was to evaluate the effect of vascular endothelial growth factor (VEGF) administration around the autologous nerve graft on nerve recovery in a rat model. METHODS: A total of 69 rats were randomly divided into three experimental groups. A 10-mm sciatic nerve defect was made and reconstructed with the reversed nerve segment. Group I received an osmotic pump with saline, group II received an osmotic pump with VEGF, and group III added a silicone tube around the nerve graft to decrease the surrounding blood supply. Nine animals in each group were sacrificed on day 3 to evaluate improvement in new vessel formation. In each group 14 animals were sacrificed at 16 weeks after the initial procedure to evaluate the functional motor nerve regeneration using compound muscle action potential, isometric tetanic force, wet muscle weight, and nerve histomorphometry. RESULTS: The average vascular density on day 3 was 10.7% in group I, 21.4% in group II, and 0.9% in group III. These differences were significant. However, the average maximum isometric tetanic force at 16 weeks was 54.4% in group I, 57.5% in group II, and 47.6% in group III. No difference was found with or without VEGF administration. Histomorphometric analysis was also not significantly different between the groups. CONCLUSIONS: New vessel formation on autologous nerve graft was enhanced by VEGF administration. However, the neovascularization effect of VEGF administration did not translate into better motor nerve recovery.

The influence of nerve conduits diameter in motor nerve recovery after segmental nerve repair.

Many conduits have demonstrated potential to substitute nerve autografts; however, the influence of conduit inner diameter (ID) has never been studied as a separate parameter. This experimental study compared motor recovery after segmental nerve repair with two different ID collagen conduits: 1.5 and 2.0 mm. In addition, the conduits were analyzed in vitro to determine the variations of ID before and after hydration. Thirty rats were divided into three groups: 2.0 mm ID, 1.5 mm ID, and a control group autograft. After 12 weeks, the 1.5 mm ID group demonstrated significant increase in force (P < 0.0001) and weight (P < 0.0001) of the tibialis anterior muscle and better histomorphometry results of the peroneal nerve (P < 0.05) compared to 2.0 mm ID group; nevertheless, autograft results outperformed both conduits (P < 0.0001). Conduits ID were somewhat smaller than advertised, measuring 1.59 ± 0.03 mm and 1.25 ± 0.0 mm. Only the larger conduit showed a 6% increase in ID after hydration, changing to 1.69 ± 0.02 mm. Although autografts perform best, an improvement in motor recovery can be achieved with collagen conduits when a better size match conduit is being used. Minimal changes in collagen conduits ID can be expected after implantation.

Does the addition of a nerve wrap to a motor nerve repair affect motor outcomes?

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non-operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar-decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats.

The Result of In Situ Pinning for Valgus Impacted Femoral Neck Fractures of Patients over 70 Years Old.

PURPOSE: We aimed to evaluate the outcome of fixation with cannulated screws for valgus impacted femoral neck fractures in patients over 70 years of age. MATERIALS AND METHODS: We reviewed the outcome in 33 patients older than 70 years with valgus impacted femoral neck fractures who were treated with cannulated screws fixation from May 2007 to December 2010. These patients were followed for at least a year. We assessed the fixation failure rate, body mass index (BMI), bone mineral density (BMD) of proximal femur, distance between screw tip and joint, number of screws and time from fracture to operation. RESULTS: We identified six patients (18.2%) with failure. Two patients with subtrochanteric fractures through the screw insertion site and another patient with osteonecrosis were excluded from the fixation failure group. No difference was found in age, BMI, BMD of proximal femur, distance between screw tip and joint, number of screws and time from fracture to operation between failure and non-failure groups. CONCLUSION: The failure rate of cannualted screw fixation for valgus impacted femoral neck fractures in the elderly patients was not low. Risk of failure should be considered in the management of these patients and accurate assessment for fracture type should be performed using computed tomogram and clinical evaluation.

Rupture of flexor tendons as a complication of a distal radius fracture.

Two cases are reported of flexor tendon rupture of ulnar side fingers as a complication after distal radius fracture. One was associated with a prominent distal volar lip of fracture site, the other with a relatively volarly displaced ulnar head due to the dorsally tilted distal radius due to malunion. These may be unique cases of flexor tendon rupture with conservatively treated patients.

Return of motor function after repair of a 3-cm gap in a rabbit peroneal nerve: a comparison of autograft, collagen conduit, and conduit filled with collagen-GAG matrix.

BACKGROUND: The purpose of this study was to evaluate the motor nerve recovery in a rabbit model after repair of a 3-cm gap in the peroneal nerve with a conduit filled with a collagen-GAG (glycosaminoglycan) matrix and compare the results with those after reconstruction with an autograft or an empty collagen conduit. METHODS: Forty-two male New Zealand rabbits were divided into three experimental groups. In each group, a unilateral 3-cm peroneal nerve defect was repaired with a nerve autograft, an empty collagen conduit, or a conduit filled with a collagen-GAG matrix. At six months, nerve regeneration was evaluated on the basis of the compound muscle action potentials, maximum isometric tetanic force, and wet muscle weight of the tibialis anterior muscle as well as nerve histomorphometry. RESULTS: The autograft group had significantly better motor recovery than the conduit groups. The empty collagen conduits and conduits filled with the collagen-GAG matrix led to results that were similar to each other. CONCLUSIONS: On the basis of this rabbit model, autologous nerve grafting remains the gold standard in the reconstruction of 3-cm segmental motor nerve defects. CLINICAL RELEVANCE: Segmental motor nerve defects should be reconstructed with autograft nerves. The use of a collagen conduit filled with a collagen-GAG matrix for motor nerve reconstruction should be limited until additional animal studies are performed.

Functional evaluation in the rat sciatic nerve defect model: a comparison of the sciatic functional index, ankle angles, and isometric tetanic force.

BACKGROUND: The sciatic functional index has long been the standard method of assessing motor recovery in the rat sciatic nerve model. The relative subjective nature of the assessment has led to development of newer methods, including video gait analysis and quantitative measurement of isometric tetanic muscle force. METHODS: Forty male Lewis rats, each with a 10-mm segmental defect in the sciatic nerve, were divided randomly into two groups: rats in group I underwent repair with reversed autograft, and those in group II received a collagen conduit. Video gait analyses were performed at 0, 4, 8, and 12 weeks, and sciatic functional index and ankle angles in four different walking phases were recorded. Isometric tetanic force of the tibialis anterior muscle was also measured at 12 weeks and correlated with sciatic functional index and video gait analysis data. RESULTS: The sciatic functional index results did not correlate with isometric tetanic force. Significantly, the sciatic functional index could not be measured in 26 percent of the rats at 8 weeks and 59 percent of the rats at 12 weeks secondary to toe contractures. Among various ankle angle measurements, only the ankle angle in toe-off phase correlated well with isometric tetanic force. CONCLUSIONS: Toe contractures occurred more frequently in rats with better nerve recovery, and interfered with evaluation of the motor recovery using the sciatic functional index method. Ankle angle in toe-off phase measured from video gait analysis is a useful parameter that reflects functional recovery of the muscle force.

The effect of collagen nerve conduits filled with collagen-glycosaminoglycan matrix on peripheral motor nerve regeneration in a rat model.

BACKGROUND: Bioabsorbable unfilled synthetic nerve conduits have been used in the reconstruction of small segmental nerve defects with variable results, especially in motor nerves. We hypothesized that providing a synthetic mimic of the Schwann cell basal lamina in the form of a collagen-glycosaminoglycan (GAG) matrix would improve the bridging of the nerve gap and functional motor recovery. METHODS: A unilateral 10-mm sciatic nerve defect was created in eighty-eight male Lewis rats. Animals were randomly divided into four experimental groups: repair with reversed autograft, reconstruction with collagen nerve conduit (1.5-mm NeuraGen, Integra LifeSciences), reconstruction with collagen nerve conduit filled with collagen matrix, and reconstruction with collagen nerve conduit filled with collagen-GAG (chondroitin-6-sulfate) matrix. Nerve regeneration was evaluated at twelve weeks on the basis of the compound muscle action potential, maximum isometric tetanic force, and wet muscle weight of the tibialis anterior muscle, the ankle contracture angle, and nerve histomorphometry. RESULTS: The use of autograft resulted in significantly better motor recovery compared with the other experimental methods. Conduit filled with collagen-GAG matrix demonstrated superior results compared with empty conduit or conduit filled with collagen matrix with respect to all experimental parameters. Axon counts in the conduit filled with collagen-GAG matrix were not significantly different from those in the reversed autograft at twelve weeks after repair. CONCLUSIONS: The addition of the synthetic collagen basal-lamina matrix with chondroitin-6-sulfate into the lumen of an entubulation repair significantly improved bridging of the nerve gap and functional motor recovery in a rat model. CLINICAL RELEVANCE: Use of a nerve conduit filled with collagen-GAG matrix to bridge a motor or mixed nerve defect may result in superior functional motor recovery compared with commercially available empty collagen conduit. However, nerve autograft remains the gold standard for reconstruction of a segmental motor nerve defect.

Factors affecting outcome of triceps motor branch transfer for isolated axillary nerve injury.

PURPOSE: Triceps motor branch transfer has been used in upper brachial plexus injury and is potentially effective for isolated axillary nerve injury in lieu of sural nerve grafting. We evaluated the functional outcome of this procedure and determined factors that influenced the outcome. METHODS: A retrospective chart review was performed of 21 patients (mean age, 38 y; range, 16-79 y) who underwent triceps motor branch transfer for the treatment of isolated axillary nerve injury. Deltoid muscle strength was evaluated using the modified British Medical Research Council grading at the last follow-up (mean, 21 mo; range, 12-41 mo). The following variables were analyzed to determine whether they affected the outcome of the nerve transfer: the age and sex of the patient, delay from injury to surgery, body mass index (BMI), severity of trauma, and presence of rotator cuff lesions. The Spearman correlation coefficient and multiple linear regression were performed for statistical analysis. RESULTS: The average Medical Research Council grade of deltoid muscle strength was 3.5 ± 1.1. Deltoid muscle strength correlated with the age of the patient, delay from injury to surgery, and BMI of the patient. Five patients failed to achieve more than M3 grade. Among them, 4 patients were older than 50 years and 1 was treated 14 months after injury. In the multiple linear regression model, the delay from injury to surgery, age of the patient, and BMI of the patient were the important factors, in that order, that affected the outcome of this procedure. CONCLUSIONS: Isolated axillary nerve injury can be treated successfully with triceps motor branch transfer. However, outstanding outcomes are not universal, with one fourth failing to achieve M3 strength. The outcome of this procedure is affected by the delay from injury to surgery and the age and BMI of the patient.

Distal interphalangeal joint arthrodesis with a headless compression screw: morphometric and functional analyses.

INTRODUCTION: We performed radiologic measurement of the distal and middle phalanges in volunteers to determine the size of a headless compression screw suitable for distal interphalangeal (DIP) joint arthrodesis in Korean subjects and report on clinical results using an acutrak fusion screw. MATERIALS AND METHODS: Radiologic measurements on the distal and middle phalanx were performed to determine the optimal size of screw. Five hundred fingers from 50 adult Koreans without any abnormality on plain radiographs were selected and anteroposterior and lateral radiographs were obtained for measurements. For the distal phalanx, the narrowest diameter of the cortical bone was measured to determine the minimal diameter of the screw that would not penetrate the cortex. For the middle phalanx, the narrowest diameter of the medullary canal was measured to determine the appropriate size of the screw for fixation. Between May 2004 and December 2007, there were 23 fingers in 22 patients (6 male, 16 female) that had finger DIP joint or thumb IP joint arthrodesis performed with the acutrak fusion screws. At the final follow up, time to union, complications, clinical fusion angle, pinch power, visual analogue score (VAS) for pain and the Korean version of the disabilities of the arm, shoulder and hand (DASH) questionnaire were assessed. RESULTS: In the distal phalanx, the narrowest diameter of the cortex was 2.64 ± 0.51 mm for the little finger. In the middle phalanx, the narrowest diameter of the medullary canal was 1.83 ± 0.50 mm for the little finger and 4.17 ± 0.68 for the thumb. The mean time to union was 10 weeks (range 8-12). The mean clinical fusion angle of the DIP joint was 11.9° (range 0-20). The VAS pain score was 0.4 (range 0-3). Pinch power was 75% of the normal side. The average Korean DASH score was 5 points (range 0-8). We experienced one intraoperative fixation failure for thumb IP joint arthrodesis caused by a wide medullary canal of the proximal phalanx. CONCLUSION: The acutrak fusion screw was a feasible and adequate tool for DIP arthrodesis, particularly in Koreans. However, meticulous attention to technique was important to avoid complications in some little fingers. If preoperative radiographs suggest the thumb has a wide medullary canal, alternate methods of fixation should be considered.