Fermion Masses and Mixings in a String-Inspired Model

We study quark and lepton mass matrix textures in a model containing an additional $U(1)_X$ gauge symmetry with origins in string compactification. The $U(1)_X$ symmetry is broken near the string scale, and we assume that the anomalies are canceled by the Green-Schwarz mechanism. We also assume that fermion mass matrices are generated by an additional scalar field through an approach analogous to that of Froggatt and Nielsen. By requiring that supersymmetry not be broken at the high scale, we can derive the vacuum expectation value of this scalar field to then predict fermion masses and mixings for any given $X$ charge assignment. We examine the possible solutions, and although in the simplest model they do not completely agree with experiment, the results are close enough to merit further inspection.Comment: 21 pages, 1 figure included in text, plain LaTeX. Minor corrections, two references adde

Nonvascularized Bone Grafting Defers Joint Arthroplasty in Hip Osteonecrosis

A variety of nonvascularized bone grafting techniques have been proposed with varying degrees of success as treatment alternatives for osteonecrosis of the femoral head. The success of these procedures may be enhanced using ancillary growth and differentiation factors. We retrospectively reviewed 33 patients (39 hips) with osteonecrosis of the hip who had nonvascularized bone grafting procedures with supplemental OP-1. We compared the outcomes in this cohort to similar patients treated nonoperatively or with other nonvascularized bone grafting procedures. We used a trapdoor to make a window at the head-neck junction to remove necrotic bone and packed the excavated area with autogenous cancellous bone graft, marrow, and OP-1. The minimum followup was 24 months (mean, 36 months; range, 24–50 months). We performed no further surgery in 25 of 30 small- and medium-sized lesions (80%) but did in two of nine large lesions. Hips with Ficat Stage II disease were not reoperated in 18 of 22 cases during the followup periods. Our short-term results compare similarly to nonoperative treatment and other reports of nonvascularized bone grafting. With the addition of ancillary growth factors, these procedures effectively reduce donor site morbidity and may defer joint arthroplasty in selected patients

Do Modern Techniques Improve Core Decompression Outcomes for Hip Osteonecrosis?

Core decompression procedures have been used in osteonecrosis of the femoral head to attempt to delay the joint destruction that may necessitate hip arthroplasty. The efficacy of core decompressions has been variable with many variations of technique described. To determine whether the efficacy of this procedure has improved during the last 15 years using modern techniques, we compared recently reported radiographic and clinical success rates to results of surgeries performed before 1992. Additionally, we evaluated the outcomes of our cohort of 52 patients (79 hips) who were treated with multiple small-diameter drillings. There was a decrease in the proportion of patients undergoing additional surgeries and an increase in radiographic success when comparing pre-1992 results to patients treated in the last 15 years. However, there were fewer Stage III hips in the more recent reports, suggesting that patient selection was an important reason for this improvement. The results of the small-diameter drilling cohort were similar to other recent reports. Patients who had small lesions and were Ficat Stage I had the best results with 79% showing no radiographic progression. Our study confirms core decompression is a safe and effective procedure for treating early stage femoral head osteonecrosis