Tatsuo Yokoi

Incidence and Characteristics of Carpal Fractures Occurring Concurrently With Distal Radius Fractures

PURPOSE To investigate the incidence and characteristics of carpal fractures occurring concurrently with distal radius fractures and to determine the risk factors for this combination. METHODS We retrospectively analyzed 161 consecutive patients with 170 distal radius fractures who were treated between 2007 and 2011. Posteroanterior, lateral, and oblique radiographs of the wrist were examined, as were computed tomography scans when available. We evaluated the incidence and characteristics of carpal fractures occurring concurrently with distal radius fractures and the patient factors of gender, age, AO/ASIF classification, and energy of the injury. RESULTS Of the 170 distal radius fractures, 11 (7%) also had 1 or 2 carpal fractures. Of the 15 carpal fractures, 8 were scaphoid, 2 triquetrum, 2 pisiform, 1 capitate, 1 trapezium, and 1 hamate. Eleven of the 15 carpal fractures were diagnosed by computed tomography alone. Male gender, patients of lower mean age, AO/ASIF type B, and high-energy trauma significantly raised the risk of simultaneous fractures of the distal radius and carpals. CONCLUSIONS The incidence of carpal fractures occurring concurrently with distal radius fractures was not negligible, and almost all carpal fractures had no or minimal displacement. Suspicion of carpal fractures occurring concurrently with distal radius fracture should be high, and computed tomography should be considered, in males, young patients, and those with AO/ASIF type B fractures and high energy trauma.

Traumatic closed index extensor tendon rupture at the musclotendinous junction: a report of two cases.

This report describes two cases of traumatic closed index extensor tendon rupture at the musclotendinous junction. Both patients were injured when their work gloves were caught in the revolving parts of machines, and both were treated surgically. One of the patients completely ruptured the index extensor digitorum communis (EDC) and the extensor indicis proprius (EIP) tendons at the musclotendinous junction of dorsal forearm. In this patient, the distal stump of the index EDC tendon was sutured to the middle EDC tendon in an end-to-side juncture. The other patient completely ruptured the EIP tendon and partially ruptured the index EDC tendon at the musclotendinous junction. In this patient, tendon transfer of the extensor digiti minimi (EDM) to the EIP tendon and plication of the index EDC tendon were performed. In both cases, surgical intervention enabled the patients to extend their index fingers almost normally; however, the former complained of inability to extend his index finger independently. Tendon transfer of the EDM in cases of index extensor tendon rupture at the musclotendinous junction is a good method to restore ability to independently extend the index finger. However, consideration should be given to anatomical variation in the little finger. The EDC tendon is sometimes absent leaving the EDM tendon as the only extensor tendon to the little finger.

Palmar-divergent dislocation of the scaphoid and the lunate

We describe a patient with palmar-divergent dislocation of the scaphoid and lunate. After successful closed reduction, the scapholunate and lunotriquetral ligaments were sutured through the dorsal approach, and the anterior capsule was sutured through the palmar approach. The scapholunate and lunotriquetral joints were fixed with Kirschner wires for 7 weeks. At the 1-year follow-up, magnetic resonance imaging showed no evidence of avascular necrosis of the scaphoid or lunate, and radiographs showed no evidence of the dorsal and volar intercalated segment instability patterns associated with carpal instability. However, flexion of the scaphoid and a break in Gilula’s line remained. To our knowledge, this is the first report showing treatment of palmar-divergent dislocation of the scaphoid and lunate by suturing the carpal interosseous ligaments.

Ductile-to-brittle transition in tensile failure due to shear-affected zone with a stress-concentration source: a comparative study on punched-plate tensile-failure characteristics of precipitation-hardened and dual-phase steels

The effect of shear-affected zone (SAZ), with a stress-concentration source induced by the punching process, on tensile properties was investigated. Tests using honed specimens (which have the same shapes and stress-concentration without any SAZ) and smooth specimens were conducted to compare the effect with that of the punched specimens. Dual-phase steel, which has a high work-hardening ability and low yield strength, and precipitation-hardened steel, which has a low work-hardening ability and high yield strength, were used in the tests. Materials with two tensile strength grades were prepared from both types of steel. Only the precipitation-hardened steel with higher strength grade punched specimen showed a brittle fracture with extremely short fracture-elongation, whereas the other specimens showed a ductile fracture. The fracture surface analysis revealed that cracks initiated in the maximum shear stress plane of the SAZ under tensile loading at first. We call the crack “shear crack.” The steel which showed brittle fracture used in this study easily exhibited plastic-strain localization compared with the other steels. If the shear crack is sharp, then the transition from ductile to brittle failure tends to occur. Furthermore, the strength characteristics of the punched specimen depend on the crack length dependency of the strength resistance and the failure phenomenon of the original material.

Pedicle screw system with telescoping function in surgical treatment for osteoporotic spine

Operative procedure The pedicle screws in the proximal site of osteotomy are not connected to the rod to permit spinal shortening in the postoperative course. When a connector is used between a pedicle screw and a rod, the connector is not fixed to the rod to allow it to slide on the rod. When a connector is not used, the rod is only placed in the screw head with reinforcement by some sets of cranial sublaminar taping. U-rod is used to not injure the skin when postoperative junctional kyphosis (PJK) occurs.

Quantitative Analysis of Carbon in Ferrite in Dual-Phase Steels by Mechanical Loss Measurements

To establish the method for determining the amount of carbon in the ferrite phase in ferrite + martensite dual-phase low-alloy steels, mechanical loss measurements have been performed on a series of Fe–C alloys with varying constitution. The observed mechanical loss spectra of two-phase alloys turned out to be simple superposition of those of single phase alloys, of ferrite and of martensite. The concentrations of carbon in solution evaluated from the magnitude of the Snoek relaxation in the two-phase alloys agree well with those expected from the Fe–C phase diagram. It is thus possible to selectively analyse the carbon dissolved in the ferrite phase in the complex structure, at least in simple binary alloys.