The significance of matching radius of curvature of the radial head implant and the capitellum in implant selection is evaluated. A mismatch of radius of curvature could lead to point loading, reducing contact area, creating large contact stresses, resulting in arthritis, pain, and other complications. Radial head (RH) implant size is chosen by reconstruction outside of the radiocapitellar joint capsule measuring the RH diameter and length, which is replicated for implant selection. RH radius of curvature (RC) is rarely part of the decision although important in determining contact area.Summary
Introduction
For injuries to the lower leg or forearm, supplemental support from soft tissue compression (STC) with a splint or brace-like system and combined with external fixation could be done effectively and quickly with a minimal of facilities in the field. Soft tissue compression (STC) in functional braces has been shown to provide rigidity and stability for most closed fractures, selected open fractures and can supplement some other forms of fracture fixation. However, soft tissue injuries are compromised in war injuries. This study was designed to evaluate if STC can provide adequate rigidity and stability either with, or without other forms of fixation techniques of simple fractures or bone defects after standardised soft tissue defects. The load was applied either axially or in bending as the bending configuration is more like conditions when positioned on a stretcher in the field.Summary
Introduction
Consistent load distributions with over-sizing of radial head implants show minimal variance in interosseus ligament (IOL) and triangular-fibrocartilage complex (TFCC) tension, both of which are essential in distribution of load at the elbow. Introduction:Changes in loading distribution at the elbow have not been studied with radial head (RH) arthroplasty. Difficulty arises concerning distribution variability between loading methods and magnitudes, and with implant oversizing. RC joint capsule were exposed using the Kocher approach in seven fresh-frozen cadaver Humeri. Specimens were loaded axially in an MTS machine with humeri at 90° and wrist neutral. The arms were cycled in load control between 13N–130N until steady-state was reached for each trial. After loading in neutral, the arms were rotated to 60° supination (60S) and 60° pronation (60P), the test repeated. The radial head was excised and Co-Cr implant inserted. Sizings 0mm, +2mm, +4mm were simulated using 2mm plastic spacers on the stem. A Tekscan pressure map transducer at RC recorded loading. The recorded Tekscan loads were organised according to sizing (native, 0mm, +2mm, +4mm) for each specimen. The max/min load values were recorded and the difference, ΔL was calculated. The Max and ΔL values from each sizing were percentage paired with the respective native value. The ΔL values were used to discern load distribution. A linear regression was done using the RC loading plotted against the applied load to visualise the change of load distribution with changing applied loads. Data was analyzed using one-way analysis of variance.Summary
Method
Radial head arthroplasty is a reliable procedure with good functional outcomes when faced with irreparable radial head fractures. Since the first attempt at arthroplasty by Speed in 1941, there have been a variety of different designs created for radial head prostheses. There has been considerable recent interest in bipolar radial head components. However, to date, there have been few biomechanical studies comparing bipolar components to their monopolar counterparts. We examine the effects of alteration of axial length of the radial head prosthesis and force conveyed at the radiocapitellar joint in a head-to-head comparison of bipolar implants to monopolar implants. Sixteen fresh-frozen, sided cadaveric arms were utilized. Radial heads were resected and either a monopolar, rigid, metal radial head prosthesis (Solar, Stryker, Mahwah, NJ) was implanted or a bipolar metal prosthesis used (Katalyst, Integra, Plainsboro, NJ). Adjustments of radial head length were made in 2 mm increments using radiolucent washers to create an understuffed (−2), neutral (0), and overstuffed (+2, +4) effect, see Fig. 1. Forearms were cyclically loaded in compression from 13N to 130N with the forearm in neutral. Radiocapitellar forces were measured using Tekscan (Tekscan, Inc., Boston, MA) pressure sensors with radial head length set at −2 mm, 0, +2 mm and +4 mm and comparisons were made with the neutral (0) radial head, see Fig. 2. Multivariant ANOVA with Tukey's HSD correction was used for statistical analysis.INTRODUCTION:
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