Publications by authors named "Shohei Omokawa"

99 Publications

Dynamic analysis of the ulnar nerve and cubital tunnel morphology using ultrasonography; A cadaveric study.

J Shoulder Elbow Surg 2022 Jul 8. Epub 2022 Jul 8.

Department of Orthopedic Surgery, Nara Medical University, Kashihara, Japan.

Background: The causes of ulnar neuropathy at the elbow are unclear. The authors hypothesized that the humeral trochlea protrudes into the cubital tunnel during elbow flexion and causes a dynamic morphologic change of the ulnar nerve in the cubital tunnel.

Methods: An ultrasonic probe was fixed to the ulnar shafts of 10 fresh cadavers with an external fixator, and dynamic morphology of the cubital tunnel and ulnar nerve was observed. The distance from the Osborne band to the trochlea (OTD), distance from ulnar nerve center to the trochlea (UTD), and short and long axis diameters of the nerve at 30°, 60°, 90°, 120° of elbow flexion were recorded. We compared the OTD, UTD, and the flattening of the ulnar nerve between angle of flexion using single factor analysis of variance. Correlation between the ulnar nerve flattering, OTD, and UTD was examined using Spearman's correlation coefficient. A p value less than 0.05 was used to denote statistical significance.

Results: Flattening of the ulnar nerve progressed with increasing elbow flexion and was significantly different between 0° and 60°, 90°, and 120° (p = 0.03 at 60º, p < 0.01 at 90º and 120º). OTD decreased with elbow flexion, and there was a significant difference among all elbow flexion angles (all p < 0.01). UTD decreased significantly from 0° flexion value to 90° flexion value (p = 0.03). Flattering of the nerve was significantly correlated with the OTD (r = 0.66, p < 0.01).

Conclusions: A positive correlation was found between the protrusion of the humeral trochlea into the cubital tunnel during elbow flexion and ulnar nerve flattening using cadaveric elbow and ultrasonography.
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http://dx.doi.org/10.1016/j.jse.2022.05.026DOI Listing
July 2022

Simultaneous Bilateral Chronic Volar Lunate Dislocation: A Case Report.

JBJS Case Connect 2022 04 15;12(2). Epub 2022 Jun 15.

Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.

Case: A 24-year-old professional judo competitor suffered injuries to both the wrists when he fell on his back while lifting a 90-kg barbell in the bilateral dorsiflexed wrist position. Simultaneous bilateral volar lunate dislocation had been missed for a year. The degenerated lunates were simultaneously removed using a palmar approach. At 12 months postoperatively, the patient returned to judo competitions without pain. Radiography showed no progression of the intercarpal alignment abnormality.

Conclusion: Simultaneous bilateral chronic volar lunate dislocation is extremely rare. Long-term follow-up is necessary to check for carpal alignment.
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http://dx.doi.org/10.2106/JBJS.CC.22.00094DOI Listing
April 2022

Acromioclavicular joint instability on cross-body adduction view: the biomechanical effect of acromioclavicular and coracoclavicular ligaments sectioning.

BMC Musculoskelet Disord 2022 Mar 23;23(1):279. Epub 2022 Mar 23.

Department of Orthopedic Surgery, Nara Medical University, 840 Shijoutyou, Kashihara City, Nara, 634-5821, Japan.

Background: The acromioclavicular (AC) and coracoclavicular (CC) ligaments are important stabilizers of the AC joint. We hypothesized that AC and trapezoid ligament injuries induce AC joint instability and that the clavicle can override the acromion on cross-body adduction view even in the absence of conoid ligament injury. Accordingly, we investigated how sectioning the AC and CC ligaments contribute to AC joint instability in the cross-body adduction position.

Methods: Six fresh-frozen cadaveric shoulders were used in this study, comprising five male and one female specimen, with a mean age of 68.7 (range, 51-87) years. The left side of the trunk and upper limb, and the cervical and thoracic vertebrae and sternum were firmly fixed with an external fixator. The displacement of the distal end of the clavicle relative to the acromion was measured using an electromagnetic tracking device. We simulated AC joint dislocation by the sequential resection of the AC ligament, AC joint capsule, and CC ligaments in the following order of stages. Stage 0: Intact AC and CC ligaments and acromioclavicular joint capsule; stage 1: Completely sectioned AC ligament, capsule and joint disc; stage 2: Sectioned trapezoid ligament; and stage 3: Sectioned conoid ligament. The superior clavicle displacement related to the acromion was measured in the horizontal adduction position, and clavicle overriding on the acromion was assessed radiologically at each stage. Data were analyzed using a one-way analysis of variance and post-hoc tests.

Results: Superior displacement was 0.3 mm at stage 1, 6.5 mm at stage 2, and 10.7 mm at stage 3. On the cross-body adduction view, there was no distal clavicle overriding at stages 0 and 1, and distal clavicle overriding was observed in five cases (5/6: 83%) at stage 2 and in six cases (6/6: 100%) at stage 3.

Conclusion: We found that AC and trapezoid ligament sectioning induced AC joint instability and that the clavicle could override the acromion on cross-body adduction view regardless of conoid ligament sectioning. The traumatic sections of the AC and trapezoid ligament may lead to high grade AC joint instability, and the distal clavicle may subsequently override the acromion.
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http://dx.doi.org/10.1186/s12891-022-05245-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8943985PMC
March 2022

Arthroscopic Lunate Excision Provides Excellent Outcomes for Low-Demand Patients with Advanced Kienböck's Disease.

Arthrosc Sports Med Rehabil 2021 Oct 28;3(5):e1387-e1394. Epub 2021 Aug 28.

Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.

Purpose: To examine the clinical outcomes of arthroscopic lunate excisions for advanced Kienböck's disease.

Methods: Fifteen patients (six men and nine women; mean age: 65 years; range: 48-83 years) with advanced Kienböck's disease, who underwent arthroscopic lunate resection between April 2008 and March 2016, were reviewed clinically and radiographically after a follow-up of >2 years (mean: 29 months; range: 24-60 months). Clinical parameters, such as wrist range of motion, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) score, and patient-rated wrist evaluation (PRWE) score were evaluated. Radiographic parameters included radioscaphoid angle, scaphocapitate angle, carpal height ratio, ulnar-triquetrum distance, and the scaphoid-triquetrum distance. Wilcoxon's signed-rank test was used to compare measurement results.

Results: During the final follow-up, patients exhibited significant improvements, such as 42.9° in wrist range of motion ( = .009), 24.5% of the contralateral side in grip strength ( = .001), 26.2 points in DASH score ( = .002), and 37.8 points in PRWE score ( .001), compared with the preoperative values. The radioscaphoid and scaphocapitate angles significantly increased by 4.8° ( = .0027) and 3.7° ( = .0012), respectively. The carpal height ratio, ulnar-triquetrum distance, and scaphoid-triquetrum distance significantly decreased by 0.05 ( .001), 2.6 mm ( .001), and 1.3 mm ( = .0012), respectively.

Conclusions: Our results suggest that arthroscopic lunate excisions provided excellent postoperative pain relief and functional recovery within 2 years of follow-up. Changes in carpal alignment and stress concentration on the radial side of the carpal bones could occur in the long term; however, arthroscopic lunate excision can be a good surgical option for treating low-demand patients with advanced Kienböck's disease.

Level Of Evidence: Level IV, therapeutic case series.
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http://dx.doi.org/10.1016/j.asmr.2021.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8527252PMC
October 2021

Treatment of painful median nerve neuroma using pedicled vascularized lateral antebrachial cutaneous nerve with adipofascial flap: a cadaveric study and exploration of clinical application.

J Plast Surg Hand Surg 2022 Apr 9;56(2):74-78. Epub 2021 Jun 9.

Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Japan.

The most common procedure for the treatment of painful median nerve neuroma is coverage with vascularized soft tissue following external neurolysis. However, the ideal treatment should include reconnecting the proximal and distal stumps of the damaged nerve to allow the growth of regenerating axons to their proper targets for a functional recovery. We developed a useful technique employing radial artery perforator adipofascial flap including the lateral antebrachial cutaneous nerve (LABCN) to repair the median nerve by vascularized nerve grafting and to achieve coverage of the nerve with vascularized soft tissue. In an anatomical study of 10 fresh-frozen cadaver upper extremities, LABCN was constantly bifurcated into two branches at the proximal forearm (mean: 8.2 cm distal to the elbow) and two branches that run in a parallel manner toward the wrist. The mean length of the LABCN branches between the bifurcating point and the wrist was 18.2 cm, which enabled inclusion of adequate length of the LABCN branches into the radial artery perforator adipofascial flap. The diameters of the LABCN branches (mean: 1.7 mm) were considered suitable to bridge the funiculus of the median nerve defect after microsurgical internal neurolysis. In all cadaver upper extremities, the 3-cm median nerve defect at the wrist level could be repaired using the LABCN branches and covered with the radial artery perforator adipofascial flap. On the basis of this anatomical study, the median nerve neuroma was successfully treated with radial artery perforator adipofascial flap including vascularized LABCN branches.
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http://dx.doi.org/10.1080/2000656X.2021.1933994DOI Listing
April 2022

Partial Trapeziotrapezoid Resection and Thumb Range of Movement After Trapeziometacarpal Joint Fusion-A Biomechanical Study.

J Hand Surg Am 2021 12 2;46(12):1126.e1-1126.e7. Epub 2021 May 2.

Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.

Purpose: Trapeziometacarpal (TMC) joint arthrodesis is an effective treatment for stage III osteoarthritis. Although this procedure alleviates thumb pain and restores grip power and pinch strength, persistent limitation of thumb movement is inevitable. This biomechanical study aimed to investigate the altered kinematics of thumb circumduction motion after TMC joint arthrodesis and subsequent excision of the trapeziotrapezoid (TT) and trapezio-second metacarpal (T-2MC) joint spaces.

Methods: Eight cadaver upper extremities were mounted on a custom testing apparatus. The hand and carpal bones were fixed to the apparatus, except for the first metacarpal bone, trapezium, and trapezoid. A 50-g load was applied at the tip of the first metacarpal head to generate passive thumb circumduction. An electromagnetic tracking system measured the angular and rotational displacement of the first metacarpal. All specimens were tested in 4 conditions: intact, after simulated TMC joint fusion, after subsequent excision of 3 mm of bone at the TT joint space, and after additional 3 mm resection at the T-2MC joint space.

Results: After simulated TMC arthrodesis, the range of angular motion of thumb circumduction decreased to 25% that of the intact thumb. Subsequent resections at the TT and T-2MC joint spaces increased circumduction ranges to 49% (TT joint) and 73% (TT plus T-2MC joints) that of the intact thumb. The range of thumb rotational motion showed a similar trend.

Conclusions: Trapeziometacarpal arthrodesis decreased the range of both angular and rotational motion during thumb circumduction. Subsequent resections at the paratrapezial space increased the range of thumb motion, suggesting that hypermobility of the paratrapezial joints increases thumb mobility after TMC joint fusion.

Clinical Relevance: Patients with hypermobile paratrapezial joints may have larger thumb movement after TMC joint fusion. Additional resections of the TT and T-2MC joint spaces may further mobilize the thumb in patients who complain of stiffness after TMC fusion.
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http://dx.doi.org/10.1016/j.jhsa.2021.03.016DOI Listing
December 2021

Magnetic Resonance Imaging Evaluation of Acute Plastic Deformation of a Pediatric Radius.

J Hand Surg Asian Pac Vol 2021 Jun;26(2):280-283

Division of Hand Surgery, Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.

Acute plastic deformation of long bones is more common in young children. We report a case of an acute plastic deformation of a pediatric radius via magnetic resonance imaging (MRI) evaluation. A 15-year-old boy fell on landing after a jump while practicing soccer, which injured his right forearm. He was diagnosed with a radial neck fracture and a medial epicondylar fracture of the humerus on the basis of plain radiograms. MRI was additionally performed and showed abnormal shadows indicating intramedullary bleeding at multiple bamboo-joint-like deformity sites of the radius. Surgery was performed and injury completely healed. Acute plastic deformation of long bones was often diagnosed by simple radiographic imaging. To our knowledge, there has been no previous reports of plastic deformation evaluated by MRI. If bone plastic deformation is missed, functional impairments such as limited range of motion remain; thus, an early diagnosis of acute bone plastic deformation by performing MRI is recommended.
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http://dx.doi.org/10.1142/S2424835521720085DOI Listing
June 2021

Anatomical Study of Stabilizing Structures of the Extensor Carpi Ulnaris Tendon Around the Wrist.

J Hand Surg Am 2021 10 9;46(10):930.e1-930.e9. Epub 2021 Apr 9.

Department of Anatomy, Faculty of Medicine, Chiang Mai University, Thailand; Excellence in Osteology Research and Training Center, Chiang Mai University, Thailand; Department of Hand Surgery, Nara Medical University, Kashihara Nara, Japan. Electronic address:

Purpose: The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis in the upper extremity, but the exact location of stenosis is not fully understood. The objective of this study was to investigate the detailed anatomy of structures surrounding the extensor carpi ulnaris (ECU) tendon around the wrist.

Methods: Fifty fresh human cadaveric wrists were used for gross observation and morphology measurements of the sixth dorsal compartment and the ECU subsheath. An additional 13 wrists were used for histological examination. We evaluated the morphology of supporting structures in 3 regions: the ulnar groove (zone I), the ulnar styloid process (zone II), and the triquetrum (zone III).

Results: The fibro-osseous tunnel comprising the ulnar groove and the overlying subsheath (zone I) stabilized the ECU tendon, and the subsheath had thin membranous collagen fibers attached to the periosteum. We consistently found the distal extension of ECU subsheath (zone II), which connected the ulnar styloid process and the dorsal radioulnar ligament. Variations in the length of the distal extension increased with the forearm in pronation. Collagen fiber thickness around the ECU tendon in zone II was greater than that of zone I. In zone III, the overlying extensor retinaculum and septa, which were composed of thick circumferential collagen structures, supported the ECU tendon by attaching to the triquetrum on both sides of the ECU tendon. We found the presence of an ulnar septum of the sixth compartment attached to the triquetrum in 84% of dissected wrists.

Conclusions: The ECU tendon was supported by the ECU subsheath, which had thin and elastic collagen fibers over the ulnar groove. Distal extension of the subsheath and surrounding radial and ulnar extensor retinaculum septa attached to the triquetrum provided thicker supporting structures.

Clinical Relevance: Stenosing ECU tenosynovitis may occur not only in the ulnar groove but also in the more distal ulnar styloid process and triquetrum areas.
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http://dx.doi.org/10.1016/j.jhsa.2021.02.008DOI Listing
October 2021

Biomechanical comparison of arthroscopic and open lunate excisions in the cadaveric wrist.

Clin Biomech (Bristol, Avon) 2021 04 26;84:105343. Epub 2021 Mar 26.

Department of Orthopaedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, Japan.

Background: In advanced Kienböck disease, unreconstructible lunate should be excised as a salvage procedure. There is a lack of information about the biomechanical approaches evaluating the carpal kinematics after lunate excision. We hypothesized that arthroscopic lunate excision would not break the ring structure of the proximal carpal row, preventing carpal instability. We aimed to investigate changes in carpal kinematics following arthroscopic and open lunate excisions.

Methods: We used upper extremities from five fresh cadavers and simulated arthroscopic and open lunate excisions. Arthroscopic lunate excision was performed to preserve the attachment sites of intrinsic and extrinsic carpal ligaments to the lunate. Open lunate excision was conducted with sectioning of the intrinsic and extrinsic carpal ligaments. Using a three-dimensional space electromagnetic tracking device, rotation angles of the scaphoid and triquetrum and the change of scaphotriquetrum distance were measured under axial loading. We compared the rotation angles and the change of scaphotriquetrum distance among intact wrists, open, and arthroscopic lunate excisions.

Findings: No Significant differences in the rotation angle of the scaphoid and triquetrum or the change of scaphotriquetrum distance were found between intact wrist and arthroscopic lunate excision. The triquetrum significantly dorsiflexed and supinated in wrists with open lunate excisions compared with intact wrists. Significant differences in the change of scaphotriquetrum distance were found between intact and openly excised wrists and between arthroscopic and open excisions.

Interpretation: Arthroscopic lunate excision potentially prevented kinematic change of the proximal carpal row under axial loading by maintaining the integrity of attachment sites of carpal ligaments.
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http://dx.doi.org/10.1016/j.clinbiomech.2021.105343DOI Listing
April 2021

Impacted intraarticular fragments of distal radius fractures: A radiographic characterization and analysis of reliability and diagnostic accuracy.

J Orthop Sci 2022 Mar 9;27(2):384-388. Epub 2021 Mar 9.

Department of Orthopedic Surgery, Nara Medical University, Kashihara, Nara, 634-8522, Japan.

Background: Reduction using ligamentotaxis may not be effective enough to treat impacted intraarticular fragments of distal radius fractures. Articular incongruence resulting from the loss of reduction is a risk factor for postoperative osteoarthritis and worse clinical outcome. This study aimed to analyze the radiographic characterization of the impacted intraarticular fragments of distal radius fractures using two/three-dimensional computed tomography (CT). Further, we assessed the reliability and diagnostic accuracy in detecting the fragments using plain radiographs.

Methods: We analyzed 167 three-dimensional CT images of the intraarticular distal radius fractures and selected 12 fractures with impacted intraarticular fragments. We recorded the location, size, and displacement of the fragment using CT images. In addition, six examiners evaluated 25 fractures including those 12 fractures having the fragments using plain radiographs for detecting the fragments and their displacements. Further, we evaluated the reliability and diagnostic accuracy of the plain radiographs in the detection of the fragment.

Results: Fifteen impacted intraarticular fragments were found in 12 wrists. The displacement of the scaphoid facet fragment was significantly larger than that of the lunate facet fragment in CT measurement (7.0 mm and 3.6 mm). Inter and intraobserver reliability of the diagnosis for the fragment in plain radiographs were poor and fair (κ: 0.14 and κ:0.27). Diagnostic accuracy in detecting the fragment in plain radiographs generated mean sensitivity: 0.4, mean specificity: 0.73, and mean accuracy: 0.58. The mean sensitivity in detecting a lunate facet fragment was lower than that of a scaphoid facet fragment in plain radiographs (0.24 and 0.44).

Conclusion: Impacted intraarticular fragments were found in 7% of intraarticular distal radius fractures. We observed low reliability and sensitivity in detecting the fragment using plain radiographs. Preoperative recognition of the fragments using plain radiograph were difficult, even though the magnitude of step-off of the scaphoid facet fragment was large.
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http://dx.doi.org/10.1016/j.jos.2020.12.029DOI Listing
March 2022

The Role of the Acromioclavicular Ligament in Acromioclavicular Joint Stability: A Cadaveric Biomechanical Study.

Orthop J Sports Med 2021 Feb 10;9(2):2325967120982947. Epub 2021 Feb 10.

Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.

Background: Acromioclavicular (AC) joint dislocation is evaluated using the radiologically based Rockwood classification. The relationship between ligamentous injury and radiological assessment is still controversial.

Purpose/hypothesis: To investigate how the AC ligament and trapezoid ligament biomechanically contribute to the stability of the AC joint using cadaveric specimens. The hypothesis was that isolated sectioning of the AC ligament would result in increased instability in the superior direction and that displacement >50% of the AC joint would occur.

Study Design: Controlled laboratory study.

Methods: Six shoulders from 6 fresh-frozen cadavers were used in this study. Both the scapula and sternum were solidly fixed on a customized wooden jig with an external fixator. We simulated distal clavicular dislocation with sequential sectioning of the AC and coracoclavicular (CC) ligaments. Sectioning stages were defined as follows: stage 0, the AC ligament, CC ligament, and AC joint capsule were left intact; stage 1, the anteroinferior bundle of the AC ligament, joint capsule, and disk were sectioned; stage 2, the superoposterior bundle of the AC ligament was sectioned; and stage 3, the trapezoid ligament was sectioned. The distal clavicle was loaded with 70 N in the superior and posterior directions, and the magnitudes of displacement were measured.

Results: The amounts of superior displacement averaged 3.7 mm (stage 0), 3.8 mm (stage 1), 8.3 mm (stage 2), and 9.5 mm (stage 3). Superior displacement >50% of the AC joint was observed in stage 2 (4/6; 67%) and stage 3 (6/6; 100%). The magnitudes of posterior displacement were 3.7 mm (stage 0), 3.7 mm (stage 1), 5.6 mm (stage 2), and 9.8 mm (stage 3). Posterior displacement >50% of the AC joint was observed in stage 3 (1/6; 17%).

Conclusion: We found that the AC ligaments contribute significantly to AC joint stability, and superior displacement >50% of the AC joint can occur with AC ligament tears alone.

Clinical Relevance: The AC ligament plays an important role not only in horizontal stability but also in vertical stability of the AC joint.
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http://dx.doi.org/10.1177/2325967120982947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7878954PMC
February 2021

Biomechanical Effects of Radioscapholunate Fusion With Distal Scaphoidectomy and Triquetrum Excision on Dart-Throwing and Wrist Circumduction Motions.

J Hand Surg Am 2021 Jan 6;46(1):71.e1-71.e7. Epub 2020 Nov 6.

Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.

Purpose: Distal scaphoid and triquetrum excisions can improve the range of wrist motion after radioscapholunate (RSL) fusion, but little is known about the kinematics of dart-throwing and global circumduction motions. We hypothesized that these excisions could increase the range of motion without causing midcarpal instability.

Methods: Seven fresh-frozen cadaver upper extremities were mounted on a testing apparatus after isolation and preloading of the tendons of the flexor carpi radialis, flexor carpi ulnaris, extensor carpi radialis, and extensor carpi ulnaris. Sequential loadings of the flexor carpi ulnaris and extensor carpi radialis simulated active dart-throwing motion. Passive circumferential loading produced the wrist circumduction motion. We measured the range of wrist motions with an electromagnetic tracking system in 4 experiments: intact, simulated RSL fusion, RSL fusion with distal scaphoid excision, and RSL fusion with distal scaphoid and total triquetrum excisions. To evaluate midcarpal stability, we conducted passive mobility testing of the distal carpal row in the radial, volar, ulnar, and dorsal directions.

Results: Radioscapholunate fusion decreased the dart-throwing motion to a mean of 46% of the baseline value; distal scaphoid and triquetrum excisions increased the mean arc to 50% and 62%, respectively. Radioscapholunate fusion diminished the wrist circumduction to a mean of 43% of the baseline value, which increased to a mean of 58% and 74% after distal scaphoid and triquetrum excision, respectively. A significant increase in radial deviation was noted after distal scaphoid excision, and subsequent triquetrum excision significantly increased motion in the ulnar-palmar direction. Regarding midcarpal stability, dorsal translation significantly increased after distal scaphoid and triquetrum excisions.

Conclusions: Distal scaphoid and triquetrum excision after RSL fusion improved both dart-throwing and circumduction motions, but dorsal midcarpal instability occurred.

Clinical Relevance: Subsequent carpal excisions may improve short-term outcome by increasing motions in a RSL-fused wrist; however, a potential risk of midcarpal instability should be considered.
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http://dx.doi.org/10.1016/j.jhsa.2020.08.009DOI Listing
January 2021

Biomechanical analysis of simultaneous distal and proximal radio-ulnar joint instability.

Clin Biomech (Bristol, Avon) 2020 08 7;78:105074. Epub 2020 Jun 7.

Department of Orthopedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, Japan.

Background: Simultaneous dislocation of the proximal and distal radio-ulnar joints without bony injuries has been reported, but the mechanism remains unclear. We investigated concurrent proximal and distal radio-ulnar joint instability after sequential sectioning of the annular ligament, triangular fibrocartilage complex, and quadrate ligament.

Methods: We performed this biomechanical study with six fresh-frozen cadaveric upper extremities. Proximal and distal radio-ulnar joint displacement was measured using an electromagnetic tracking device during passive mobility testing with anterior, lateral, and posterior loads on the radial head with pronation, supination, and neutral rotation. Measurements were statistically analyzed using the generalized linear mixed model.

Findings: Proximal radio-ulnar joint instability was significantly greater after sectioning of the annular (lateral: 1.4%, P < .05; posterior: 0.7%, P < .05) and quadrate (lateral: 43.7%, P < .05; posterior: 29.5%, P < .05) ligament. Distal radio-ulnar joint instability was significantly greater in every sequential stage (final stage: anterior: 24.1%, P < .05; lateral 21.0%, P < .05; posterior: 31.3%, P < .05). Finally, significant simultaneous instability of the joints was observed after sectioning of the annular ligament, triangular fibrocartilage complex, and quadrate ligament, and neutral rotation potentially induced gross instability.

Interpretation: Our ligament injury model induced simultaneous proximal and distal radio-ulnar joint instability without bony or interosseous membrane injury, probably induced by severe soft tissue injury. Proximal radio-ulnar joint instability may influence distal radio-ulnar joint instability from pivoting of the interosseous membrane. Our findings will help surgeons evaluate the magnitude of soft tissue injury and plan surgery for patients with simultaneous proximal and distal radio-ulnar joint instability.
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http://dx.doi.org/10.1016/j.clinbiomech.2020.105074DOI Listing
August 2020

Robust method to create a standardized and reproducible atrophic non-union model in a rat femur.

J Orthop 2020 Sep-Oct;21:223-227. Epub 2020 Mar 28.

Department of Orthopedic Surgery, Nara Medical University, Kashihara, Nara, 634-8522, Japan.

Objective: No evidence exists about which biological approach is more reliable for creating non-union model. We investigated how to create a reproducible atrophic non-union model in a rat femur.

Methods: We compared three groups: simple osteotomy (group A), partial periosteum cauterization (group B), and extensive periosteum and bone marrow resection (group C).

Results: All samples in group C demonstrated atrophic non-union in radiological, histological, and biomechanical analyses, however half of the samples in group B showed fracture healing at week 16.

Conclusion: Extensive resection of periosteum and bone marrow is important for a reproducible atrophic non-union model in a rat femur.
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http://dx.doi.org/10.1016/j.jor.2020.03.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7132052PMC
March 2020

Vascularized pedicled bone graft from the distal radius supplied by the anterior interosseous artery for treatment of ulnar shaft nonunion: An anatomical study of cadavers and a case report.

Microsurgery 2020 May 12;40(4):479-485. Epub 2020 Feb 12.

Department of Orthopedic Surgery, Nara Medical University, Kashihara, Japan.

Background: A vascularized distal radius graft can be a reliable solution for the treatment of refractory ulnar nonunion. The aim of this study is to establish the anatomical basis of a vascularized bone graft pedicled by the anterior interosseous artery and report its clinical application, using cadaveric studies and a case report.

Methods: Fourteen fresh frozen cadaveric upper limbs were used. The branches of the anterior interosseous artery (the 2, 3 intercompartmental supraretinacular artery and the fourth extensor compartment artery) were measured at the bifurcation site. The anatomical relationship between the anterior interosseous artery and motor branches of the posterior interosseous nerve was investigated. An anterior interosseous artery pedicled bone flap was used in a 48-year-old woman with refractory ulnar nonunion.

Results: There were two variations depending on whether the 2,3 intercompartmental supraretinacular artery branched off distally or proximally from the terminal motor branch of the posterior interosseous nerve. The proximal border of the graft was located at an average of 10.5 cm (range, 6.5-12.5 cm) from the distal end of the ulnar head in the distal type (57%) and 17.5 cm (range, 9.5-21.5 cm) in the proximal type (43%). In the clinical application, successfully consolidation was achieved 4 months post-surgery. The patient had not developed any postoperative complications until the 2-year postoperative follow-up.

Conclusions: The anterior interosseous artery-pedicled, vascularized distal radius bone graft would be a reliable alternative solution for the treatment of an ulnar nonunion located within the distal one-third of the ulna.
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http://dx.doi.org/10.1002/micr.30566DOI Listing
May 2020

Vascularized medial femoral condyle graft for nonunion after failed radiolunate arthrodesis.

Case Reports Plast Surg Hand Surg 2019 22;6(1):7-10. Epub 2019 Jan 22.

Department of Orthopedic Surgery, Nara Medical University, Kashihara city, Japan.

Since the medial femoral condyle flap was originally described in 1989, the indications for use of this versatile flap as a graft have broadened. We used this procedure in a patient with nonunion after failed arthrodesis of the radiolunate joint. Early bone union was achieved, with marked postoperative improvement in VAS and DASH scores.
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http://dx.doi.org/10.1080/23320885.2018.1544848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6968543PMC
January 2019

Safe zone of pin insertion for nonbridging external fixators in distal radial fractures: MRI analysis.

J Orthop Sci 2020 Nov 17;25(6):1003-1007. Epub 2020 Jan 17.

Department of Orthopedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan.

Background: Of the anatomical reduction and fixation methods used to treat distal radius fracture, non-bridging external fixation has the advantage of enabling early wrist motion. The surgical technique relies on successful placement of the pin in individual fracture fragments. The present study aimed to identify the safe zone of pin insertion for a non-bridging external fixator into the distal radius that avoids metal impingement of extensor tendons.

Methods: The width and length of the septal attachments of the extensor retinaculum were measured on axial MR images of 62 wrists.

Results: The 2-3 septum was the widest and longest, with a width of 2-7 mm and a location 0-36 mm proximal to the wrist joint. The width of the 1-2 septum was 2-6 mm, and was widest at 10 mm proximal to the joint. The 1-2 septum was triangular-shaped, while the 2-3 septum was oval-shaped. The 3-4 and 4-5 septa had narrow attachments and were adequate for pin insertion (with a pin 1-2 mm in width) at a position less than 8 mm proximal to the wrist. The width of the 1 R septum (radial to the 1st septum) was 2-6 mm at the radiovolar aspect of the wrist.

Conclusions: There were two safe pin insertion sites; the first was safe at the distal aspect only (8-10 mm proximal to the wrist) and included the 1-2, 3-4, and 4-5 septa, while the second was safe from 0 mm to 32-38 mm proximal to the wrist and included the 1 R and the 2-3 septa. The 1 R septum had adequate size for use as a new pin insertion site that aligns in the internervous plane and has minimal risk of superficial radial nerve injury.
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http://dx.doi.org/10.1016/j.jos.2019.12.005DOI Listing
November 2020

Clinical outcomes of unstable metacarpal and phalangeal fractures treated with a locking plate system: a prospective study.

J Hand Surg Eur Vol 2020 Jul 20;45(6):582-587. Epub 2020 Jan 20.

Department of Hand Surgery, Nara Medical University, Kashihara, Japan.

We prospectively assessed clinical and radiological outcomes of locking plate fixation in treating unstable fractures in 11 metacarpals, 15 proximal phalanges, and eight middle phalanges in 34 consecutive patients from October 2011 to December 2016. Median length of follow-up was 14 months (range 12-24). The motion of finger joints, bony union, and complication rates were recorded. The median postoperative range of motion of the two interphalangeal joints and the metacarpophalangeal joint was 82% of the contralateral hands. Fractures in the three locations had significantly different recovery of the finger motion, with the best recovery for the metacarpal fractures. Closer distance between the plate edge and joint line was associated with a more limited range of the finger motion. The clinical outcomes approached an acceptable level at final follow-up. Finger stiffness is unavoidable after locking plate fixation of metacarpal and phalangeal fractures even with early hand therapy, with stiffness occurring in 10 out of 34 cases at the time of final follow-up 1 year after surgery. II.
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http://dx.doi.org/10.1177/1753193419899332DOI Listing
July 2020

Dorsal Intercarpal Ligament Preserving Arthrotomy and Capsulodesis for Scapholunate Dissociation.

Tech Hand Up Extrem Surg 2020 Mar;24(1):43-46

Orthopedic Surgery, Nara Medical University, Kashihara.

Carpal instability secondary to scapholunate (SL) ligament tears can lead to a significant disability of the wrist. Different surgical procedures have been proposed to treat SL instability. A variety of dorsal capsulodesis techniques tethering the scaphoid have been used in patients with SL dissociation. We report a novel technique of modified dorsal intercarpal ligament (DICL) capsulodesis for the treatment of SL dissociation. The surgical indication for this procedure is complete SL ligament tear with a reducible carpal malalignment and no secondary osteoarthritis. This procedure is indicated when the remnant of torn ligament in the dorsal SL interosseous space is available for repair. First, carpal malalignment is corrected and the scaphoid and the lunate are temporarily fixed with a transosseous screw or Kirschner wires. Using a dorsal approach, the DICL is then exposed, which originates from the triquetrum and attaches to the scaphoid, trapezium, and trapezoid. The distal and proximal borders of the ligament are identified and elevated without detaching the attachment sites. The DICL is transferred proximally to reinforce the dorsal SL interosseous ligament. The wrist joint is immobilized for 3 weeks postoperatively, and dart-throwing motion is permitted until temporary SL fixation is removed at 2 to 3 months after surgery. A wrist brace is recommended until 3 to 6 months after the first surgery depending on the patient's occupation and sports activity.
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http://dx.doi.org/10.1097/BTH.0000000000000273DOI Listing
March 2020

Effect of soft tissue injury and ulnar angulation on radial head instability in a Bado type I Monteggia fracture model.

Medicine (Baltimore) 2019 Nov;98(44):e17728

Department of Orthopedic Surgery.

The effects of soft tissue damage and ulnar angulation deformity on radial head instability in Monteggia fractures are unclear. We tested the hypothesis that radial head instability correlates with the magnitude of ulnar angular deformity and the degree of proximal forearm soft tissue injury in Bado type I Monteggia fractures.We performed a biomechanical study in 6 fresh-frozen cadaveric upper extremities. Monteggia fractures were simulated by anterior ulnar angulation osteotomy and sequential sectioning of ligamentous structures. We measured radial head displacement during passive mobility testing in pronation, supination, and neutral rotation using an electromagnetic tracking device. Measurements at various ligament sectioning stages and ulnar angulation substages were statistically compared with those in the intact elbow.Radial head displacement increased with sequential ligament sectioning and increased proportionally with the degree of anterior ulnar angulation. Annular ligament sectioning resulted in a significant increase in displacement only in pronation (P < .05). When the anterior ulnar deformity was reproduced, the radial head displaced least in supination. The addition of proximal interosseous membrane sectioning significantly increased the radial head displacement in supination (P < .05), regardless of the degree of anterior ulnar angulation.Our Monteggia fracture model showed that radial head instability is influenced by the degree of soft tissue damage and ulnar angulation. Annular ligament injury combined with a minimal (5°) ulnar deformity may cause elbow instability, especially in pronation. The proximal interosseous membrane contributes to radial head stability in supination, regardless of ulnar angulation, and proximal interosseous membrane injury led to significant radial head instability in supination.
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http://dx.doi.org/10.1097/MD.0000000000017728DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6946299PMC
November 2019

Favoured treatments for fingertip defects and finger amputation distal to the distal interphalangeal joint in my unit and in Japan.

Authors:
Shohei Omokawa

J Hand Surg Eur Vol 2019 12 31;44(10):1101-1102. Epub 2019 Aug 31.

Department of Hand Surgery, Nara Medical University, Nara, Japan.

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http://dx.doi.org/10.1177/1753193419871664DOI Listing
December 2019

Tamai Zone 1 Fingertip Amputation: Reconstruction Using a Digital Artery Flap Compared With Microsurgical Replantation.

J Hand Surg Am 2019 Aug 10;44(8):655-661. Epub 2019 May 10.

Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.

Purpose: The surgical treatment of fingertip amputations is controversial. This study was designed to compare the clinical results of 2 surgical procedures for fingertip amputation: reconstruction with a digital artery flap and microsurgical replantation.

Methods: Between 2003 and 2015, 37 patients with Tamai zone 1 fingertip amputation of the index or middle finger were treated by reconstruction with a digital artery flap (n = 23) or microsurgical replantation (n = 14). Data for these patients were evaluated retrospectively. Nerve suture was not conducted in microsurgical replantation because spontaneous sensory recovery is expected in zone 1 replantation. Primary outcomes included hand dexterity (Purdue Pegboard Test), and disability of the upper extremity (Disabilities of the Arm, Shoulder, and Hand score). Secondary outcomes included strength (key pinch), digital sensitivity (Semmes-Weinstein test), and finger mobility (% total active motion).

Results: The average follow-up period was 34 months. There was no significant difference in the primary outcomes between the 2 groups. The reconstruction group showed significantly better results for the secondary outcomes.

Conclusions: This study suggests that the 2 procedures were comparable regarding postoperative activities of daily living and hand performance, but reconstruction using a digital artery flap gave better objective functional outcomes than microsurgical replantation.

Type Of Study/level Of Evidence: Therapeutic IV.
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http://dx.doi.org/10.1016/j.jhsa.2019.03.016DOI Listing
August 2019

A microsurgery training model using konjac flour noodles.

Microsurgery 2019 11 29;39(8):775-776. Epub 2019 Apr 29.

Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Japan.

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http://dx.doi.org/10.1002/micr.30463DOI Listing
November 2019

Comparison of Five Years Clinical and Radiological Outcomes between Progressive and Non-Progressive Wrist Osteoarthritis after Volar Locking Plate Fixation of Distal Radius Fractures.

J Hand Surg Asian Pac Vol 2019 Mar;24(1):30-35

‡ Department of Hand Surgery, Nara Medical University, Kashihara, Nara, Japan.

Background: This study aimed to identify the effect of the progression of postoperative wrist osteoarthritis on 5 years clinical and radiological outcomes after volar locking plate fixation of distal radius fractures.

Methods: Altogether, 56 patients with distal radius fractures were followed up 5 years after surgery. Clinical assessment was performed using the Mayo modified wrist score, a visual analogue scale of pain, the Japanese version of the Disabilities of the Arm, Shoulder, and Hand score, and Patient-related wrist evaluation. Standardized wrist radiographs were used to assess wrist morphology and the Knirk and Jupiter's degree of osteoarthritis. Multivariate logistic regression was used to analyze postoperative morphological changes in the wrist and carpal alignment regarding their correlation with progression of wrist osteoarthritis.

Results: Progression of postoperative wrist osteoarthritis was recognized in 37 of the 56 cases (66.1%). Compared with the clinical outcomes at the time of the fracture union completion, almost clinical outcomes improved up to 5 years follow-up time as well as at 1 year after surgery. The range of wrist flexion at 5 years follow-up was significantly less in the progressive osteoarthritis group than in those with non-progressive osteoarthritis. The persistent step-off immediately after surgery significantly affected the postoperative progression of wrist osteoarthritis. Changes in the radial inclination, volar tilt, and radioscaphoid angle correlated with progression of wrist osteoarthritis. The highest correlation was with the change of radioscaphoid angle.

Conclusions: Good clinical results were maintained at 5 years after surgery, but progression of postoperative wrist osteoarthritis interfered with improvement of wrist flexion. Change in the radioscaphoid angle was the factor that was most highly correlated with progression of postoperative wrist osteoarthritis.
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http://dx.doi.org/10.1142/S2424835519500061DOI Listing
March 2019

Scaphoid Motion of the Wrist with Scapho-trapezio-trapezoidal Osteoarthritis-A Pilot Study.

Curr Rheumatol Rev 2020 ;16(3):206-209

Department of Hand Surgery, Nara Medical University, Nara, Japan.

Background: The purpose of this study was to investigate scaphoid motion within the scapho-trapezio-trapezoidal (STT) joint during wrist motion in the presence of STT joint osteoarthritis (OA).

Methods: We studied 11 wrists with STT OA and 5 normal wrists. Computed tomography (CT) images were acquired in five wrist positions (maximum active flexion, extension, radial deviation, ulnar deviation, and neutral position). The 3-dimensional surface models of the radius and scaphoid were constructed and the motion of scaphoid relative to the radius was calculated.

Results And Conclusions: During wrist flexion/extension motion, the scaphoid rotated mostly in the flexion/extension plane. The angle tended to be smaller in STT OA than in normal. During wrist radioulnar deviation, the scaphoid was in an extended position in neutral wrist in STT OA. The motion of scaphoid in STT OA was divided into two types: a rigid type and mobile type. The mobile type rotated closer to the flexion/extension plane than the rigid type. Taking into account scaphoid motion during wrist movement before surgery may provide better results in the treatment of STT OA.
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http://dx.doi.org/10.2174/1573397115666190115125430DOI Listing
August 2021

Reverse vascularized bone graft of the lateral distal humerus for non-union of the radial neck fracture: anatomical study and case report.

J Plast Surg Hand Surg 2019 Feb 12;53(1):20-24. Epub 2019 Jan 12.

a Department of Orthopaedic Surgery , Nara Medical University , Kashihara , Japan.

A few treatment options for radial neck non-union have been reported, including radial head excision, radial head replacement, and internal fixation with a bone graft. We describe a new treatment for radial neck non-union using a reverse vascularized bone graft of the lateral distal humerus. In the anatomical study, the posterior radial collateral artery (PRCA) was dissected in eight fresh-frozen cadaver arms. The number of branches from the PRCA to the humerus was determined, and the distances from these branches to the lateral epicondyle of the humerus were measured. We then used this information to create a reverse vascularizedhumeral bone graft, which was used to treat non-union of a radial neck fracture in a 73-year-old female. There were two to four PRCA branches (mean: 3.3) entering the bone. The distance from the branches to the lateral epicondyle of the humerus ranged from 2.5 to 10.8 cm. The mean distances from the most proximal and distal PRCA branches to the lateral epicondyle of the humerus were 7.6 cm and 3.4 cm, respectively. The case of non-union of a radial neck fracture was successfully treated with a reverse vascularized humeral bone graft. There were no major complications, and radiographs showed bony union at 8 weeks postoperatively. This procedure may become a new option for the treatment of non-union of fractures of the radial head and neck, as it enables preservation of the radial head, which is an important structure in the elbow and proximal radioulnar joints.
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http://dx.doi.org/10.1080/2000656X.2018.1520122DOI Listing
February 2019

Quality of life in patients with toe-to-hand transplantation.

J Plast Surg Hand Surg 2018 Dec 16;52(6):359-362. Epub 2018 Nov 16.

a Department of Orthopaedic Surgery , Nara Medical University , Kashihara , Japan.

Objective: Toe-to-hand transplantation is a reliable procedure that replaces like-with-like in cases of a lost thumb or finger. The aim of this study is to investigate the effects of toe transplantation on patients from the perspectives of quality of life (QOL) and disability.

Methods: Ten patients with traumatic amputation of a digit underwent reconstruction with toe transplantation. The mean age at injury was 40.2 years (range 17-59 years). Reconstructive options were 5 wrap-around flaps to 2 thumbs and 3 index fingers; 2 second-toe transplantations to 2 middle fingers, and 3 hemipulp-free flaps from the great toe to a thumb and an index finger. We hypothesized that toe transplantation would improve postoperative QOL and disability. Outcome assessments included completion of the SF-36, SAFE-Q, and DASH questionnaires before and after reconstruction. Scores on each test were calculated and intra-individual comparisons were made.

Results: All scores for the eight SF-36 health domains improved, with a significant difference in Vitality from before to after surgery. In contrast, scores for all five SAFE-Q items worsened, with significant changes for the 'Pain and Pain-Related' and 'Physical Functioning and Daily Living' subscales. DASH scores improved after surgery in all cases.

Conclusions: Our results suggest that toe-to-hand transplantation for amputated finger reconstruction is a good option in terms of improved QOL. However, worsened SAFE-Q scores imply that donor site problems could be expected and must be taken into account during surgical planning.
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http://dx.doi.org/10.1080/2000656X.2018.1520123DOI Listing
December 2018

Reconstruction of a metacarpal head defect due to bite injury: two case reports.

Case Reports Plast Surg Hand Surg 2018 25;5(1):62-67. Epub 2018 Oct 25.

Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.

We present two rare cases of acute osteomyelitis after bite injury that were reconstructed with a third metacarpal base osteoarticular flap and a vascularised medial femoral trochlea osteocartilaginous flap. The outcomes show that a vascularised osteoarticular flap is a good treatment option for a metacarpal head defect.
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http://dx.doi.org/10.1080/23320885.2018.1509717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6211214PMC
October 2018

Predictors of Hand Dexterity after Single-Digit Replantation.

J Reconstr Microsurg 2019 Mar 28;35(3):194-197. Epub 2018 Aug 28.

Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.

Background:  Microsurgical replantation of the thumb and digits has become an increasingly familiar technique in clinical practice worldwide. However, successful digit replantation does not always provide better hand function than revision amputation. Little information is available regarding predictors of motor skill activities of replanted hands. Therefore, we retrospectively evaluated hand dexterity after single-digit replantation at a minimum follow-up of 1 year and analyzed the factors influencing dexterity.

Methods:  This retrospective cohort study included 23 patients treated for amputation injuries at our institution from 2014 to 2015. Patients with amputations from Tamai's zone 2 to 5 of the thumb (3 patients), index finger (11 patients), or middle finger (9 patients) who underwent digital replantation surgery and were followed up for more than 1 year were included. Follow-up evaluations were conducted at an average of 23 months postoperatively (range: 13-25 months). We hypothesized that possible factors influencing hand dexterity after single-digit replantation were patient age, injured finger, key pinch strength, Semmes-Weinstein test result, and percentage of total active motion. Relationships between the outcome variable, which was the result of the Purdue Pegboard Test of hand dexterity, and explanatory variables were analyzed using Spearman's correlation coefficient. A -value of < 0.05 indicated statistical significance.

Results:  No postoperative complications occurred. Univariate analysis indicated that decreased hand dexterity after single-digit replantation was significantly associated with older age ( = 0.001) and poor recovery of sensation, as shown by the Semmes-Weinstein test ( = 0.012).

Conclusion:  Patient age was a risk factor for low hand dexterity after replantation surgery. Recovery of finger sensitivity enhanced dexterity of motor skill activities following finger replantation surgery.
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http://dx.doi.org/10.1055/s-0038-1669446DOI Listing
March 2019

Three-Dimensional Kinematic Analysis of the Distal Radioulnar Joint in the Axial-Loaded Extended Wrist Position.

J Hand Surg Am 2019 Apr 16;44(4):336.e1-336.e6. Epub 2018 Aug 16.

Department of Orthopedic Surgery, Nara Medical University, Nara, Japan.

Purpose: To assess the wrist joints of healthy volunteers in extended and loaded states versus the unloaded state by using computed tomography (CT) to analyze the in vivo 3-dimensional movements in the distal radioulnar joint (DRUJ).

Methods: The dominant arms of 9 volunteers with healthy wrists were studied. We mounted a compression device onto the elbows in an inverted position. A 0-kg and 7-kg load each was applied during low-dose radiation CT imaging and a bone model was produced. We marked the insertion sites for the 4 radioulnar ligaments stabilizing the DRUJ: palmar superficial radioulnar ligament (PS-RUL), dorsal superficial radioulnar ligament (DS-RUL), dorsal deep radioulnar ligament (DD-RUL), and palmar deep radioulnar ligament (PD-RUL). Using Marai's method, each ligament was virtualized and the length of each simulated ligament was measured. We also computed the 3-dimensional displacement and corresponding rotation of the distal ulna where it comes into contact with the radius in the sigmoid notch.

Results: The lengths of palmar ligaments (PS-RUL and PD-RUL) increased significantly under loaded conditions, and although not significant, the length of dorsal ligaments (DS-RUL and DD-RUL) tended to increase. When the wrist was loaded, the ulna rotated toward the open palmar side.

Conclusions: The length of simulated radioulnar ligaments increased when the wrist joint was loaded in an extended position. This kinematic movement of DRUJ separation under a loading condition is different from physiological active movement.

Clinical Relevance: The 3-dimensional kinematic analysis revealed that palmar radioulnar ligaments were stretched during axial loading, suggesting that a tear of the palmer ligament can result from a fall on an outstretched hand.
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http://dx.doi.org/10.1016/j.jhsa.2018.06.019DOI Listing
April 2019
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