Toshiyasu Nakamura

Peripheral Nerve Injury: Diagnosis with MR Imaging of Denervated Skeletal Muscle—Experimental Study in Rats

PURPOSEnTo prospectively evaluate signal intensity change on T2-weighted magnetic resonance (MR) images and the time course of T2 values and T2 ratios after reinnervation in various nerve injury models in rats.nnnMATERIALS AND METHODSnInstitutional animal use and care committee approval was obtained. Thirty male rats made up four groups of rats with an injured left posterior tibial nerve (irreversible neurotmesis, reversible neurotmesis, severe axonotmesis, or moderate axonotmesis) and one control group. There were six rats in each group. Signal intensity changes were seen in the gastrocnemius muscle on the T2-weighted MR images. T2 values were also measured in vivo with the Carr-Purcell-Meiboom-Gill method. Gait function was assessed by calculating the print length factor (PLF). T2 ratios and PLFs on the injured side were compared with those on the unaffected side. Ratios of specific acquisition points within groups were compared by using repeated-measures analysis of variance. Comparisons across the five groups at each acquisition point were performed by using one-way analysis of variance with Scheffe post hoc testing. P < .05 indicated a significant difference.nnnRESULTSnThe more severe the nerve damage, the higher the signal intensity on T2-weighted MR images. There were significant differences in T2 ratios between the nerve injury groups and the control group (P < .05). Changes in T2 values and ratios depended on the degree of nerve injury. In the reversible neurotmesis group, T2 values and ratios began to decrease 28 days after surgery. In the severe and moderate axonotmesis groups, T2 values and ratios began to decrease 14 days after surgery. The starting point of functional recovery also depended on the degree of nerve injury.nnnCONCLUSIONnThe degree and prognosis of nerve injury can be evaluated by observing changes in signal intensity on T2-weighted images and the time course of T2 values and ratios.

Clinical Outcome and Histologic Findings of Costal Osteochondral Grafts for Cartilage Defects in Finger Joints

PURPOSEnFor the purpose of achieving anatomical reduction as precisely as possible, we performed osteochondral grafting from the costo-osteochondral junction in 16 patients (17 joints) with posttraumatic articular cartilage injury or avascular necrosis in finger joints. The purpose of this study was to review our series of costal osteochondral grafts in order to determine the practicality, effectiveness, and functionality of this grafting technique in a clinical setting.nnnMETHODSnPatients were followed for at least 18 months postoperatively (18-57 months; average, 28 months). The injured joints included 3 metacarpophalangeal, 9 proximal interphalangeal, 3 distal interphalangeal, and 2 thumb interphalangeal joints. The defect accounted for 50% to 100% of the articular surface (average, 63%).nnnRESULTSnThe average time until bone union of the graft was 58 days. The mean arc of motion was 13 degrees before surgery versus 58 degrees after surgery, with a mean increase of 45 degrees . In 7 patients (8 joints), an extremely small portion (approximately 1 x 1 mm in size and thinner than 0.1 mm) of the implanted cartilage was obtained via biopsy using a scalpel with the consent of the patient at the time of screw removal and was used to prepare histologic specimens, which revealed scattered chondrocytes within the matrix without differences from normal hyaline cartilage in any. The chondrocytes in the grafts appeared viable, and the reconstruction of the joint surface could be confirmed histologically.nnnCONCLUSIONSnOsteochondral grafting from the costo-osteochondral junction achieves excellent reconstruction of the injured joint without affecting other joints. This technique is particularly beneficial in cases where it is difficult to obtain allograft donors, as is often the case in Japan. Despite these encouraging findings in this small series, we believe that it is necessary to conduct further studies of this method over a longer period.

Corrective Osteotomy for Volarly Malunited Distal Radius Fracture

PURPOSEnTo retrospectively analyze consecutive cases with opening wedge corrective osteotomy of the volarly malunited distal radius with iliac bone graft, including preoperative and postoperative comparison of symptoms, visual analog scale (VAS), Japanese Society for Surgery of the Hand version of the Disabilities of the Arm, Shoulder, and Hand (DASH-JSSH) questionnaires, radiographic indices, clinical results as evaluated by modified Mayo wrist score, and complications.nnnMETHODSnSubjects were 28 patients with volarly malunited distal radius fracture treated by transverse opening wedge osteotomy with oblique iliac bone graft. Preoperative symptoms included wrist deformity, weakness of grip strength, and marked restriction of supination range. Postoperative symptoms, radiographic parameters, clinical results, and complications were analyzed at an average of 25 months of follow-up. We also analyzed the union period of the radius in younger patients (< or =45 years old) and older patients (>45 years old).nnnRESULTSnMean preoperative visual analog scale was 45, improving significantly to 3 postoperatively. Range of wrist motion improved in all 28 patients, with supination range improving from 16 degrees preoperatively to 80 degrees postoperatively. Mean preoperative DASH-JSSH score was 55, improving to 9 postoperatively. Radiography revealed that volar tilt improved from 32 degrees preoperatively to 10 degrees postoperatively, and radial inclination increased from 17 degrees to 21 degrees . Preoperative ulnar variance of +5.9 mm was corrected to -0.1 mm postoperatively. All 28 wrists demonstrated bony union at the osteotomy site after an average of 52 days (younger patients, 51 days; older patients, 54 days). No complications, significant radiographic correction loss, or nonunion were seen after at least 2 years of follow-up. Modified Mayo wrist score was excellent in 16 patients, good in 10 patients, and fair in 2 patients.nnnCONCLUSIONSnOpening wedge osteotomy for volarly malunited distal radius fracture restored bony configuration of the distal radius, decreased pain, and improved grip strength and range of wrist motion, particularly for forearm supination. No complications or noteworthy correction loss were noted after surgery, even in older patients.nnnTYPE OF STUDY/LEVEL OF EVIDENCEnTherapeutic IV.

Finger joint reconstruction with costal osteochondral graft.

ABSTRACT Cartilage disorders of the finger joint may influence hand function. Loss of integrity of the finger joint may severely compromise its stability and may lead to degenerative arthritis. Anatomical reduction of the finger cartilage should be as precise as possible in treating cartilage defects due to trauma and other causes. We have repaired cartilage defects in finger joints by arthroplasty with costal osteochondral grafting in 29 patients (30joints) since 1997. Three patients underwent total joint reconstruction using costal osteochondral grafting for complete bony ankylosis (1 metacarpophalangeal joint and 2 proximal interphalangeal joints). The purpose of this study was to describe the history, indications, and surgical techniques of the costal osteochondral graft for cartilage disorders or defects in the metacarpophalangeal and proximal interphalangeal joints.

Costal osteochondral grafts for osteochondritis dissecans of the capitulum humeri

The objective of the treatment for osteochondritis dissecans of the humeral capitulum is to prevent the occurrence of osteoarthritis and to allow the patients to return to throwing activities. In repairing osteochondral defects in advanced osteochondritis dissecans of the humeral capitulum after free body removal, we have performed block-shaped costal osteochondral grafting in 18 elbows since 1997. A block-shaped graft harvested from the transitional area between the rib and its associated cartilage was implanted to the osteochondral defect. This method allows the osteochondral defect to be repaired with uniform hyaline cartilaginous articular surface without any effect to other joints. Donor site no longer causes pain at 2 or 3 days after surgery. The purpose of this study is to describe the history, indications, and the surgical techniques of costal osteochondral grafting for advanced osteochondritis dissecans of the capitulum.

Effect of the posterior tibial and peroneal longus on the mechanical properties of the foot arch.

Background: The mechanical properties of the foot are controlled by many structures including muscles, tendons, ligaments, tarsal joints and bones. Among them, muscles make the dynamic changes of foot alignment, especially the posterior tibial (PT) and peroneal longus (PL) which contribute to maintaining the foot arch. The purpose of this study was to quantify the effect of PT and PL on the foot mechanical properties. Methods The mechanical properties with a longitudinal load to the tibia was measured in eight cadaveric feet. The measurement was carried out with absence of tendon traction (control), the presence of isolated traction of each tendon of the PT or PL, and finally after simultaneous traction of both tendons. Results The bone displacement significantly decreased with tendon traction. The stiffness significantly increased with PT traction compared to control, and significantly decreased with PL traction and with traction of both tendons. Among the four testing conditions, the energy during loading was least with isolated PT traction. The energy dissipation rate was significantly increased with PL traction and with traction on both tendons, whereas no significant difference existed with PT traction compared to control. Conclusions The PT increased the stiffness and reduces the energy stored in the foot. The PT acted to improve the energy efficiency of the load transmission. The PL decreased the stiffness and increased the energy stored. Clinical Relevance: PT and PL muscles affect the foot arch. Excessive or insufficient traction may cause some foot disorders.

An Obliquely Placed Headless Compression Screw for Distal Interphalangeal Joint Arthrodesis

PURPOSEnTo assess the outcomes of our technique involving oblique headless compression screw for arthrodesis of the thumb interphalangeal joint and the distal interphalangeal joints of the other digits.nnnMETHODSnA total of 28 joints (19 thumb interphalangeal and 9 distal interphalangeal) in 23 patients with a mean age of 65 years (range, 58-74 y) were retrospectively analyzed. All operations were performed with the Acutrak2 micro-screw. After the resection of synovium and joint cartilage by a dorsal approach, a 0.88-mm diameter guide wire was inserted at the ulnar side of the proximal phalanx in the thumb and radial side of the middle phalanx in the other digits from proximal to distal to fix the joint obliquely. We verified its position under fluoroscopic control and placed the cannulated screw from proximal to distal over the guide wire.nnnRESULTSnIntraoperative rigid fixation was obtained except for 1 case, which required additional K-wire fixation. The overall union rate was 96%. Average time to fusion was 11 weeks (range, 8-30 wk), with 76% achieving union within 3 months. There were 2 complications, 1 nonunion and 1 late infection. Other complications such as dorsal skin necrosis, nail deformity, and paresthesia did not occur.nnnCONCLUSIONSnEfforts to avoid invasion of the nailbed can be technically demanding. We believe that our proximal to distal technique with oblique placement of the headless compression screw is a straightforward and effective method with a relatively low risk of complication.nnnTYPE OF STUDY/LEVEL OF EVIDENCEnTherapeutic IV.

DORSAL DISLOCATIONS OF THE SECOND TO FIFTH CARPOMETACARPAL JOINTS: A CASE REPORT

Dislocations involving the four ulnar carpometacarpal joints are rare. These complex dislocations are considered to be due to the application of a hyperflexion force on the metacarpal heads. In the present case, an indirect hyperextension force on the metacarpal bones created a lever-arm effect resulting in rupture of the firm ligament complex of the carpometacarpal joints, inducing complete dislocations of the second to fifth carpometacarpal joints.

Radial perilunate trans-styloid trans-triquetrum fracture dislocation: a case report.

We present a rare case of radial perilunate trans-styloid fracture dislocation, in which the scaphoid invaginated radially into the fractured radial styloid.

Associations between ulnar nerve strain and accompanying conditions in patients with cubital tunnel syndrome.

Pathophysiology of cubital tunnel syndrome (CubTS) is still controversial. Ulnar nerve strain at the elbow was measured intraoperatively in 13 patients with CubTS before simple decompression. The patients were divided into three groups according to their accompanying conditions: compression/adhesion, idiopathic, and relaxation groups. The mean ulnar nerve strain was 43.5 ± 30.0%, 25.5 ± 14.8%, and 9.0 ± 5.0% in the compression/adhesion, idiopathic, and relaxation groups respectively. The mean ulnar nerve strains in patients with McGowans classification grades I, II, and III were 18.0 ± 4.2%, 27.1 ± 22.7%, and 33.7 ± 24.7%, respectively. The Jonckheere-Terpstra test showed that there were significant reductions in the ulnar nerve strain among the first three groups, but not in the three groups according to McGowans classification. Our results suggest that the pathophysiology, not disease severity, of CubTS may be explained at least in part by the presence of ulnar nerve strain.