Mechanically assisted crevice corrosion (MACC) of head-neck modular taper junctions is prevalent in virtually all head neck tapers in use today. To date, no clear in vitro tests of design, material or surgical elements of the modular taper system have been reported that show which factors principally affect MACC in these tapers. Possible elements include seating load, head-neck offset, surface roughness, taper engagement length, material combination, angular mismatch, and taper diameter. The goals of this study were to use an incremental fretting corrosion test method1 to assess the above 7 elements using a design of experiments approach. The hypothesis is that only one or two principal factors affect fretting corrosion. A 27-2 design of experiment test (7 factors, ¼ factorial, n=32 total runs, 16 samples per condition per factor) was conducted. Factors included: Assembly Force (100, 4000N), Head Offset (1.5, 12 mm), Taper Locking Position (Mouth, Throat), Stem Taper Length (0.44, 0.54 in), Stem Taper Roughness (Ground, Ridged), Taper Diameter (9/10, 12/14), and Stem Material (CoCrMo, Ti-6Al-4V). The heads were CoCrMo coupled with taper coupons (DePuy Synthes, Warsaw, IN). Test components were assembled wet and seated axially with 100 or 4000N assembly force. The assemblies were immersed in PBS and potentiostatically held at −50mV vs. Ag/AgCl. Incremental cyclic loads were applied vertically to the head at 3Hz until a 4000N maximum load was reached (See Fig. 1). Fretting currents at 4000 N cyclic load were used for comparisons while other parameters, including onset load, subsidence, micromotion and pull off load were also captured. Statistical analysis was performed using Pareto charts and Student's T-tests for single factor comparisons (P < 0.05 was statistically significant).Introduction
Methods
Practitioners should maintain a high suspicion of concurrent carpal fractures in patients who present with a distal radius fracture after a fall onto an outstretched hand, particularly if forearm rotation is involved. Simultaneous scaphoid and distal radius fractures, and the importance of their identification, have been previously described in multiple reports. However, few studies have investigated the incidence of carpal fractures, in general, occurring concurrently with distal radius fractures after a common mechanism of wrist injury. The purpose of this study is to investigate the incidence and characteristics of carpal fractures occurring simultaneously with distal radius fractures after a fall onto an outstretched hand. We hope to determine whether different fall parameters, such as hand position and forearm rotation, influence the frequency of this injury.Summary
Introduction
Arthroscopic decompression of the lunate decreases clinical symptoms and slows progression of Kienböck's Disease. The purpose of this study was to investigate the outcomes of patients suffering from avascular necrosis of the lunate, or Kienböck's Disease, who received arthroscopic decompression to treat the ischemic lunate. Previous studies have demonstrated an elevated intraosseus pressure in the ischemic lunate, and it has been hypothesised that ischemia in the lunate is secondary to this elevated pressure and subsequent venous congestion, as opposed to diminished arterial supply. Based on this work we have used decompression of the lunate to prevent progression of the disease.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
When a TFCC tear is diagnosed, practitioners should maintain a high level of suspicion for the presence of a concomitant SL or LT ligament tear. Disruption of the scapholunate (SL) or lunotriquetral (LT) ligament leads to dorsal and volar intercalated segment instability, respectively, while triangular fibrocartilage complex (TFCC) tears result in distal radioulnar joint (DRUJ) instability. Viegas et al. (1993) demonstrated that 56% of grossly visualised cadaveric wrists had one or more tears of a ligament or of the TFCC. The purpose of this investigation is to quantify the incidence, distribution, and correlation of SL, LT, and TFCC tears in a large group of cadaver wrists using magnetic resonance imaging (MRI). Additionally, statistical analysis was performed to predict.Summary
Introduction
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:
METHODS:
We reviewed 15 patients with an arthrodesis of the elbow using an AO compression-plate technique, after an average follow-up of 24 months. The most common indication was an open, infected high-energy injury with associated bone loss. Arthrodesis was successful in all but one patient in whom severe deep infection necessitated amputation. Eight patients were treated with the metal partly exposed in an infected wound. After removal of the metal, all wounds healed secondarily and none had clinical or radiographic signs of sepsis at latest review. Compression-plate arthrodesis of the elbow is a generally applicable method that can be used even in cases of severe bone loss. There appears to be greater certainty of union than with other techniques, and no increased risk of subsequent fracture.
