Takaaki Moro-Oka

Effect of vitamin K2 on three-dimensional trabecular microarchitecture in ovariectomized rats.

Menatetrenone, a vitamin K2 with four isoprene units, has been reported to improve osteoporotic bone loss. The purpose of this investigation was to clarify the effect of menatetrenone on the three‐dimensional (3D) trabecular microarchitecture in ovariectomized (OVX) rats by using microcomputed tomography (MCT). Forty‐two 13‐week‐old female rats were used and divided into four groups: the OVX (OVX + MK‐4) group treated with menatetrenone, the (OVX untreated) group, the sham‐operated (Sham + MK‐4) group treated with menatetrenone, and the sham‐operated group not treated with menatetrenone (Sham untreated) group. OVX rats were fed a calcium‐deficient diet. Menatetrenone treatment was begun just after the ovariectomy, and the mean menatetrenone oral intake over the 8‐week period was adjusted to 30 mg/kg BW per day. The proximal metaphyseal region of the right tibia was evaluated by dual X‐ray absorptiometry (DXA) and MCT. A parametric analysis of the reconstructed trabecular volume was carried out using bone volume fractions, the fractal dimension calculated by the 3D box‐counting method, and the connectivity density as determined by topological analysis. Menatetrenone significantly increased the trabecular bone volume, fractal dimension, and connectivity in the OVX + MK‐4 group compared with the OVX‐untreated group (p < 0.01). Our results suggest that an 8‐week administration of menatetrenone protects against the loss of trabecular bone volume and its connectivity when treatment is begun just after the ovariectomy. Despite this apparent protection, it remains unknown whether it is possible to reestablish trabecular connectivity if therapeutic intervention occurs after the trabecular connectivity has been lost.

A new friction tester of the flexor tendon

We have developed a new device to measure the friction force and calculate the friction coefficient between a rabbit flexor tendon, a pulley and a proximal phalanx. The flexor digitorum fibularis tendon of a rabbit was taken intact with the proximal phalanx, and tendon pulleys were attached to both ends of the bone. Both ends of the tendon were clamped to acrylic plates and connected to stainless-steel plates equipped with strain gauges. A pretension of 1.96 N was applied so as not to loosen the tendon. The proximal phalanx was fixed to an acrylic plate on the actuator, which gave 8 mm of transfer to the acrylic plate at a speed of 2 mm/s. The interface between the tendon and the surrounded tissue created the friction force, when the load was applied on the distal pulley. The friction force could be obtained from the difference between the tension of both ends of the tendon, which was measured with strain gauges and sampled with a personal computer. The friction force and the friction coefficient were calculated from the measured force and the applied load. The load and the pre-loading time, which was defined as loading duration before gliding, were varied in order to observe the change of the friction coefficient. The friction coefficient was not affected by the load and increased with the pre-loading time. The value of mu(s) ranged from 0.027 to 0.111 (0.072 +/- 0.023), and that of (mu)d ranged from 0.010 to 0.069 (0.039 +/- 0.014) (pre-loading time was 5 s). Our method will allow for the examination of various surgical treatments and lubricants. Moreover, it can be applied to other tissues of any animals with similar structures to the rabbits digitorum.

Co-occurrence of subchondral insufficiency fracture of the femoral head and contralateral femoral neck fracture in a rheumatic patient receiving steroid treatment

We describe a 79-year-old woman with rheumatoid arthritis who suffered from subchondral insufficiency fracture of the femoral head (SIF) and contralateral femoral neck fracture. Radiographs obtained two months after the onset of thigh pain showed collapse of the right femoral head and contralateral femoral neck fracture. MRI revealed a subchondral serpiginous low-intensity band in the right femoral head on the T2-weighted image. This case report suggests that SIF should be considered in the differential diagnoses of rheumatic patients who suffer from thigh pain without antecedent trauma.

Degenerative Change in the Adjacent Segments to the Fusion Site after Posterolateral Lumbar Fusion with Pedicle Screw Instrumentation : A Minimum 4-Year Follow-up

BACKGROUND Controversy remains regarding the subsequent degeneration of adjacent segments, and little reliable information could be found in the literature regarding long-term clinical results and adjacent segment degeneration. The objective of this study is to investigate the degenerative change of adjacent segments to the fusion site and clinical outcome after posterolateral lumbar fusion with pedicle screw instrumentation and identify the risk factors in degenerative change at adjacent segments. METHODS Thirty-two patients who underwent posterolateral lumbar fusion and were able to be followed over four years were evaluated in this study. The intervertebral disc height, percent of slip, lumbosacral joint angle, lumbar lordosis and disc angle were all examined. The postoperative progression of degeneration at adjacent segments were defined as more than a 50 % narrowing in the adjacent disc height or more than a 5 % slip in adjacent segments in comparison to the preoperative neutral lateral radiographs. The clinical results were assessed using an evaluation scores for lumbar lesions proposed by the Japanese Orthopedic Association. RESULTS Fifteen (46.8%) of the 32 patients had adjacent segment degeneration including slip or narrowing. No significant correlation was found between the adjacent segment degeneration and the recovery rate at the final follow-up. In addition, no significant correlation was observed between the adjacent segment degeneration at the lastest follow-up and postoperative radiographic measurements. CONCLUSIONS The rate of radiographic degeneration at the adjacent segments was 46.8%. No significant correlation was found between degenerative change in the adjacent segments and the clinical results. We could not identify any preoperative radiographic factors which might have influenced the segments adjacent to the fusion.