萩原 茂生

PURPOSE: MIXTURE is a simultaneous morphological and quantitative imaging sequence developed by Philips that provides high-resolution T2 maps from the imaged series. We aimed to compare the T2 maps of MIXTURE and SHINKEI-Quant (S-Q) in the cervical spine and to examine their usefulness in the functional diagnosis of cervical radiculopathy. METHODS: Seven healthy male volunteers (mean age: 31 ± 8.0 years) and one patient with cervical disc herniation (44 years old, male) underwent cervical spine magnetic resonance imaging (MRI), and T2-mapping of each was performed simultaneously using MIXTURE and S-Q in consecutive sequences in one imaging session. The standard deviation (SD) of the T2 relaxation times and T2 relaxation times of the bilateral C6 and C7 dorsal root ganglia (DRG) and C5/6 level cervical cord on the same slice in the 3D T2-map of the cervical spine coronal section were measured and compared between MIXTURE and S-Q. RESULTS: T2 relaxation times were significantly shorter in MIXTURE than in S-Q for all C6, C7 DRG, and C5/6 spinal cord measurements. The SD values of the T2 relaxation times were significantly lower for MIXTURE in the C5/6 spinal cord and C7 DRG. In cervical disc herniation, MRI showed multiple intervertebral compression lesions with spinal canal stenosis at C5/6 and disc herniation at C6/7. CONCLUSION: MIXTURE is useful for preoperative functional diagnosis. T2-mapping using MIXTURE can quantify cervical nerve roots more accurately than the S-Q method and is expected to be clinically applicable to cervical radiculopathy.

BACKGROUND: The direct anterior approach (DAA) for total hip arthroplasty (THA) is attracting attention as a minimally invasive surgery, but the learning curve to master this approach is a concern, and its effect on long-term results is unknown. The purpose of this prospective cohort study was to clarify how the learning curve affects the five-year results of DAA THA with a traction table. METHODS: Of 402 THA cases using DAA with a mobile traction table and fluoroscopy, 249 cases composed of the first 50 cases for each surgeon were assessed during a learning curve, and 153 cases were evaluated after more than 50 cases of experience. RESULTS: The five-year-implant survival rate was 99.2% both during and after the learning curve. The two-year complication rate in the learning curve group was 8.9 versus 5.9%, which was not statistically significant. The two-to-five-year complication rates also did not differ between cohorts (0 versus 0.7%). Both groups demonstrated decreased complication rates when comparing two-year complications to the two-to-five-year complications. Clinical scores significantly improved by two years and were maintained at five years in both groups. The cup-safe zone success rates were 96.4% during the learning curve and 98.7% after the learning curve. The stem-safe zone success rates were 97.2% during the learning curve and 96.1% after the learning curve. Surgical time was approximately 20 minutes shorter after the first 50 cases than during the learning curve (70.8 versus 90.6 minutes, P = 0.001). Intraoperative blood loss was significantly less after the learning curve than during the learning curve. CONCLUSION: This study implicates that the learning curve affects perioperative results such as surgical time and intraoperative blood loss, but has little effect on short-term results up to two years after surgery and no effect on mid-term results from two to five years after surgery.

OBJECTIVES: This study documents the time elapsed from the diagnosis of osteonecrosis of the femoral head (ONFH) to surgery, exploring the factors that influence ONFH severity. DESIGN: Retrospective observational study of a nationwide database. SETTING: The Kaplan-Meier method with log-rank tests was applied to examine the period from definitive diagnosis of ONFH to surgery using any surgery as the end point. For bilateral cases, the date of the first surgery was the endpoint. PARTICIPANTS: This study included 2074 ONFH cases registered in 34 university hospitals and highly specialised hospitals of the multicentre sentinel monitoring system of the Japanese Investigation Committee between 1997 and 2018. MAIN OUTCOME MEASURE: The primary outcome was the time from diagnosis to surgery. The secondary outcome was the proportion of subjects remaining without surgery at 3, 6 and 9 months, and at 1, 2 and 5 years after diagnosis. RESULTS: The median time to surgery was 9 months (IQR 4-22 months) after diagnosis of ONFH. The time to surgery was significantly shorter in the alcohol alone group and the combined corticosteroid and alcohol group than in the corticosteroid alone group (p=0.018 and p<0.001, respectively), in early stage ONFH with no or mild joint destruction (stages II and III, p<0.001), and with joint preserving surgery (p<0.001). The proportion without surgery was 75.8% at 3 months, 59.6% at 6 months, 48.2% at 9 months, 40.5% at 1 year, 22.2% at 2 years and 8.3% at 5 years. CONCLUSION: ONFH has been considered to be an intractable disease that often requires surgical treatment, but the fact that surgery was performed in more than half of the patients within 9 months from diagnosis suggests severe disease with a significant clinical impact. TRIAL REGISTRATION NUMBER: Chiba University ID1049.