Comparative evaluation of local and international reference databases for forearm densitometry: different impacts on diagnostic decisions

Does Bone Mineral Density Differ between Fan-Beam and Pencil-Beam?: A Meta-Analysis and Systemic Review

Background

Dual energy X-ray absorptiometry (DXA) has evolved from pencil-beam (PB) to narrow fan-beam (FB) densitometers. We performed a meta-analysis of the available observational studies to determine how different modes of DXA affect bone mineral density (BMD) measurements.

Methods

A total of 1,233 patients (808 women) from 14 cohort studies were included. We evaluated the differences in BMD according to the DXA mode: PB and FB. Additionally, we evaluated the differences in BMD between the 2 types of FB mode: FB (Prodigy) and the most recent FB (iDXA). Pairwise meta-analysis was performed, and weighted mean differences (WMD) were calculated for (total lumbar, total hip, and total body).

Results

No significant difference was observed in total lumbar (pooled WMD, −0.013; P=0.152) and total hip BMD (pooled WMD, −0.01; P=0.889), between PB and FB. However, total body BMD was significantly lower in the PB compared to the FB group (pooled WMD, −0.014; P=0.024). No significant difference was observed in lumbar BMD (pooled WMD, −0.006; P=0.567), total hip (pooled WMD, −0.002; P=0.821), and total body (pooled WMD, 0.015; P=0.109), between Prodigy and iDXA.

Conclusions

The results of this study warrant the recommendation that correction equations should not be used when comparing BMD from different modes. Further research is still needed to highlight the ways in which differences between DXA systems can be minimized.

On orthopedic surgical skill prediction--the limited value of traditional testing

OBJECTIVES

Primary: to assess the utility of our distal radius fracture repair model as a tool for examining residents' surgical skills. Secondary: to compare the residents' ability to achieve specific biomechanically measured fracture stability with traditional test scores.

DESIGN

Our laboratory pioneered a model that measures biomechanical qualities of a repaired distal radius fracture. Before participation, all residents to be tested completed specified knowledge examinations. During the laboratory exercise, proctors observed each resident and completed Objective Structured Assessment of Technical Skills forms. At the completion of the laboratory, each specimen was tested biomechanically. Written examinations were completed in a proctored setting and computer examinations at home following the honor system. The laboratory exercise had adequate space and materials and allowed 60 minutes to complete the procedure. Residents had equal access to x-ray imaging.

SETTING

The examination environment of the study resembled an operating room.

PARTICIPANTS

Postgraduate years 3 and 4 orthopedic residents in our program were asked to participate. The institutional review board reviewed and approved the study as exempt.

RESULTS

Fracture repair constructs capable of resisting loads expected during rehabilitation were created by approximately half the residents tested. However, traditional written and computer-based testing methods failed to predict which resident's fracture construct would pass the biomechanical testing. Prior in vivo similar case experience was not predictive.

CONCLUSIONS

The idea that "book smart does not equal street smart" applies to the tested model. To measure surgical skill acquisition and increase public safety related to surgery, it will be necessary to employ new and specific examination methods that identify the skill to be acquired and test the acquisition of this skill as precisely as possible.