Proximal half angle of the screw thread is a critical design variable affecting the pull-out strength of cancellous bone screws

Background

Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle.

Methods

Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0°, 30°, or 60°. The screws were inserted into porcine cancellous bone. At 0°, the thread faced the recipient bone vertically. Pullout tests at a rate of 30 mm/min (n = 40, each screw type) and microcomputed tomography (n = 6) were conducted.

Findings

The pull-out strength of the screws was maximal at 30°; 348.8 (SD, 44.1) N with metal and 326.6 (39.4) N with bone. It was intermediate at 0°; 301.9 (35.9) N with metal and 278.2 (30.6) N with bone. It was minimal at 60°; 126.5 (39.0) N with metal and 174.8 (29.7) N with bone. Cancellous bone was damaged between the threads at 30°, while intact cancellous bone was preserved between the threads at 0°.

Interpretation

A proximal half angle of around 30° is appropriate because the pullout force is applied to the recipient bone evenly. Commercial cancellous screws can be improved by changing the thread shape to minimize the damage to recipient bone.     

Clinical,autoimmune, and genetic characteristics of adult-onset diabetic patients with GAD autoantibodies in Japan (Ehime Study)

OBJECTIVE: To characterize the clinical, autoimmune, and genetic features in Japanese adult-onset diabetic patients with GAD autoantibodies. RESEARCH DESIGN AND METHODS: GAD autoantibodies (GADab) were screened in 4,980 diabetic patients with age of onset >20 years in the hospital-based Ehime Study, and the GADab-positive (GADab(+)) patients were then divided into two groups according to their insulin secretion and compared with nondiabetic subjects. The insulin-deficient state was defined as <0.33 nmol/l serum C-peptide (CPR) at 2 h postprandial or 6 min after a 1-mg glucagon load. RESULTS: GADab was detected in 188 (3.8%) of the 4,980 diabetic patients tested. Of these patients, 72 (38.3%) were classified as insulin deficient, 97 (51.6%) were classified as non-insulin deficient, and 19 (10.1%) were unclassified. The GADab(+) insulin-deficient patients were characterized by young age at onset of diabetes, low BMI, low maximum BMI, and high levels of HbA(1c). The prevalence of IA-2 autoantibodies and thyrogastric autoantibodies in the GADab(+) insulin-deficient patients were significantly higher than those in the GADab(+) non-insulin-deficient patients (P < 0.05). GADab(+) patients with insulin deficiency had increased frequencies of HLA DRB1*0405-DQB1*0401, *0802-*0302, and *0901-*0303 haplotypes, whereas the frequency of only HLA DRB1*0405-DQB1*0401 was increased in the case of GADab(+) non-insulin-deficient patients. Of note is the fact that the GADab(+) non-insulin-deficient group did not differ from healthy control subjects with respect to type 1 diabetes protective haplotype HLA DRB1*1502-DQB1*0601. A total of 13% of the GADab(+) patients with diabetes had genotypes comprising the DRB1*1501-DQB1*0602 or *1502-*0601 and were characterized by old age at onset of diabetes, high BMI, resistance to the insulin-deficient state, low titer of GADab, and low frequency of other organ-specific autoantibodies. CONCLUSIONS: We conclude that GADab(+) non-insulin-deficient patients differ from GADab(+) patients with insulin deficiency with respect to clinical characteristics, humoral autoimmunity to other organ-specific autoantibodies, as well as HLA class II genes.     

Relationship between body mass index and preoperative treatment response to aromatase inhibitor exemestane in postmenopausal patients with primary breast cancer

BackgroundSome studies have shown that high body mass index (BMI) is associated with inferior outcome after adjuvant therapy with anastrozole in breast cancer patients. We aimed to investigate predictive effect of BMI on clinical response to neoadjuvant therapy with exemestane in postmenopausal patients with primary breast cancer.Patients and methodsThe study group consisted of 109 patients from the JFMC 34-0601 neoadjuvant endocrine therapy trial. Patients were categorized into three groups according to BMI: low (BMI < 22 kg/m²), intermediate (22 ≤ BMI < 25 kg/m²) and high (BMI ≥ 25 kg/m²). Statistical analyses were performed to explore the predictive effect of BMI on clinical response.ResultsHigher BMI correlated with positive progesterone receptor status (p < 0.01) and low Ki-67 index (p = 0.03). Objective response rates (ORR) were 21.7% in low BMI, 56.0% in intermediate BMI and 60.6% in high BMI, respectively (p = 0.01). In a multivariate analysis, low BMI was an independent negative predictor of clinical response.ConclusionLow BMI was associated with a decreased ORR to neoadjuvant endocrine therapy with exemestane. Our results may suggest that the predictive effect of BMI varies according to the type of aromatase inhibitor and objective outcome.