Naoto Mitsugi

Effect of acetabular cup position and orientation in cemented total hip arthroplasty.

Long-term clinical results of total hip arthroplasty for patients with developmental acetabular dysplasia of the hip have been reported, but placement of the femoral head center or cup orientation remains controversial, especially with a severe anterolateral shallow acetabulum or dislocated femoral head. Results of 41 Müller and 34 Harris Design 2 cemented total hip arthroplasties were evaluated for developmental dysplasia of the hip. The femoral head center and acetabular cup inclination angle were measured from the interteardrop line. Linear wear and wear direction were measured using the Livermore technique. The best position of the femoral head center was less than 35 mm vertically from the interteardrop line and 25 mm laterally from the teardrop. Femoral head center analysis showed that hips with the cup in a lateral and superior cup position all were revised, but a superior and medial position combined with a cup inclination angle less than 40° did not require revision. Hips with a cup inclination angle more than 45° had superior and lateral penetration patterns of the polyethylene. However, hips with an inclination angle less than 35° and medial placement had medial head penetration patterns. With these all-polyethylene monolithic cemented cups, regardless of the femoral head diameter or cup thickness, better long-term results occurred with a cup inclination angle of 40° or less and medial position of the cup.

Effects of preoptic injections of gastrin, cholecystokinin, secretin, vasoactive intestinal peptide and PHI on the secretion of luteinizing hormone and prolactin in ovariectomized estrogen-primed rats

The effects of intracerebral injections of brain-gut peptides in the preoptic region on the secretion of luteinizing hormone (LH) and prolactin (PRL) were examined in ovariectomized, estrogen-primed rats. Gastrin or cholecystokinin-octapeptide injection in the preoptic region induced a moderate increase of circadian rise of LH secretion in some animals but no appreciable change in PRL secretion. Secretin injection was strikingly effective in increasing circadian rise of LH and PRL secretion. Vasoactive intestinal peptide injection completely abolished the occurrence of circadian rise of LH secretion whereas PHI injection facilitated LH secretion undergoing the circadian rhythm. The results suggest that those peptides act as neurotransmitters or neuromodulators in the preoptic region and are implicated in the regulation of LH and PRL secretion.

Effects of intracerebroventricular administration of growth hormone-releasing factor and corticotropin-releasing factor on somatostatin secretion into rat hypophysial portal blood.

To clarify the regulatory mechanisms for the secretion of somatostatin (SRIF) from the hypothalamus, the effects of intracerebroventricular (i.c.v.) administration of growth hormone-releasing factor (GRF) and corticotropin-releasing factor (CRF) on SRIF secretion into hypophysial portal blood were examined in pentobarbital-anesthetized male rats. Neither the concentration of SRIF in portal plasma nor the secretion rate of SRIF was changed after i.c.v. administration of 0.9% saline. Administration of 10 ng or 5 micrograms human GRF i.c.v. produced a significant increase in the portal plasma concentration and secretion rate of SRIF. Likewise, 5 micrograms CRF significantly increased the portal plasma concentration and secretion rate of SRIF. These results suggest that the neuropeptides GRF and CRF centrally influence SRIF secretion into hypophysial portal blood.

Low bone mineral density is associated with the onset of spontaneous osteonecrosis of the knee

Background and purpose The primary event preceding the onset of symptoms in spontaneous osteonecrosis in the medial femoral condyle (SONK) may be a subchondral insufficiency fracture, which may be associated with underlying low bone mineral density (BMD). However, the pathogenesis of SONK is considered to be multifactorial. Women over 60 years of age tend to have higher incidence of SONK and low BMD. We investigated whether there may be an association between low BMD and SONK in women who are more than 60 years old. Methods We compared the BMD of 26 women with SONK within 3 months after the onset of symptoms to that of 26 control women with medial knee osteoarthritis (OA). All the SONK patients had typical clinical presentations and met specified criteria on MRI. The BMDs measured at the lumbar spine, ipsilateral femoral neck, and knee condyles and the ratios of medial condyle BMD to lateral condyle BMD (medial-lateral ratios) in the femur and tibia were compared between the two groups. The medial-lateral ratios were used as parameters for comparisons of the BMDs at both condyles. Results The mean femoral neck, lateral femoral condyle, and lateral tibial condyle BMDs were between x% and y% lower in the SONK patients than in the OA patients (p < 0.001). The mean femoral and tibial medial-lateral ratios were statistically significantly higher in the SONK patients than in the OA patients. Interpretation A proportion of women over 60 years of age have low BMD that progresses rapidly after menopause and can precipitate a microfracture. These findings support the subchondral insufficiency fracture theory for the onset of SONK based on low BMD.

Change in Pelvic Tilt Angle 2 to 4 Years After Total Hip Arthroplasty

The purpose of this study was to evaluate the change in pelvic tilt angle (PA) in the sagittal plane in the standing and supine positions for 2 to 4 years after total hip arthroplasty (THA). Anteroposterior pelvic radiographs of 21 male and 65 female patients were investigated before and after THA yearly over 2 to 4 years. Both the standing and supine PA significantly posteriorly tilted after THA. The difference in PA between the standing and supine positions (dPA) significantly increased after THA. Although the PA in the standing and supine positions plateaued 1 year after THA, the dPA gradually increased. In addition, the percentage of patients who showed a difference of more than 10° in dPA tended to increase yearly. In particular, elderly female patients who showed posterior tilt in PA in the standing or supine positions or a large dPA before THA tended to show a dPA of more than 10° after THA.

Simultaneous Determination of Blood Levels of Corticosterone and Growth Hormone in the Male Rat: Relation to Sleep-Wakefulness Cycle

The temporal correlation of the secretion of corticosterone (CS) and growth hormone (GH) with the sleep-wakefulness cycle in adult male rats was studied by serial blood sampling at 10-min intervals over a 11-hour period from 11.00 to 22.00 h. Cortical EEGs recorded continuously during the blood sampling were scored into wakefulness and sleep, and the amounts of sleep for every 10 min was plotted against the CS and GH values. All 11-hour time series of CS, GH and amount of sleep were found to have three major ultradian rhythms with periodicities of 1.5 h and its multiples. For CS, there was a significantly negative cross-correlation between the amounts of sleep. Although the most prominent CS rhythm was the 1.5-hour period, CS secretion occurring with a 3.0-hour period had such a phase relationship with the 3.0-hour period sleep rhythm that the secretion began in the late stage of sleep cycle and reached its peak around the time of wakefulness between sleep cycles. In contrast, a GH secretory burst occurred in the early stage of the sleep cycle occurring with a 3.0-hour period, with a definite time lag after the onset of the sleep cycle. The present study demonstrates that three different functions, CS, GH secretions and sleep-wakefulness, have common ultradian rhythms with similar periods, and manifest their rhythms based on their own pacemakers. It is assumed further that each pacemaker is fixed in specific phase relations with others.

Simultaneous anterior cruciate ligament reconstruction and opening wedge high tibial osteotomy: Report of four cases.

Four patients, aged 37-50 years, with chronic anterior cruciate ligament (ACL) deficiency, medial compartment osteoarthritis and varus deformity, underwent simultaneous arthroscopic ACL reconstruction and opening wedge high tibial osteotomy using the TomoFix fixation device and hydroxyapatite wedges. The simultaneous procedure allowed our patients to perform a full weight-bearing exercise at 4 weeks after surgery. At device removal and concomitant second-look arthroscopy, all patients had either a cyclops-like lesion or partial tears at the point of contact between the reconstructed ACL and intercondylar notch. Therefore, subsequent notchplasty or re-notchplasty was required. Because of the small number of patients, the results should be considered preliminary. Given our findings of graft morbidity caused by the corrected postoperative alignment, adequate intercondylar notchplasty should be performed at the initial operation.

Spontaneous dislocation of a mobile-bearing polyethylene insert after posterior-stabilized rotating platform total knee arthroplasty: A case report

We describe a dislocation after Scorpio mobile-bearing total knee arthroplasty. This system is a rotating platform posterior-stabilized design and utilizes a single post as part of the metal tibial tray. Only one locking ring inside the socket of the polyethylene insert secures a tight connection with the post. Spontaneous dislocation between the polyethylene insert and the metal tray occurred at 22 months post surgery while rising from the supine position with slight knee flexion. Operative findings revealed failure of the locking ring and the original insert was replaced with a thicker insert. Our case and a duplicated saw bone model demonstrated that failure of the locking system resulted in the dislocation of the insert.

Medial versus lateral condyle bone mineral density ratios in a cross-sectional study: a potential marker for medial knee osteoarthritis severity.

To assess the association of bone mineral density (BMD) of the femoral and tibial condyles with knee pain and disease severity in women with symptomatic medial knee osteoarthritis (OA).

Relationship between bone density and bone metabolism in adolescent idiopathic scoliosis.

Several authors have confirmed that 27 to 38% of AIS patients had osteopenia. But few studies have assessed bone metabolism in AIS. This study assessed bone mineral density and bone metabolism in AIS patients using the bone metabolism markers, BAP and TRAP5b. The subjects were 49 consecutive adolescent AIS patients seen at our institutes between March 2012 and September 2013. Sixty-five percent of AIS patients had osteopenia or osteoporosis and 59% of AIS patients had high values for TRAP5b. The AIS patients with high values of TRAP5b had lower Z scores than those with normal values of TRAP5b. Higher rates of bone resorption are associated with low bone density in AIS patients.