Extended and weightbearing wrist 3-T MRI using a novel harness and flexible 24-channel glove coil to evaluate carpal kinematics: a pilot study in 10 volunteers.

BACKGROUND: Wrist pain in the extended or extended weightbearing positions may be incompletely evaluated using standard magnetic resonance imaging (MRI) with standard rigid clamshell coils in the neutral position. PURPOSE: To evaluate a flexible 24-channel glove coil and harness when imaging the wrist in neutral, dorsally extended, and weightbearing positions. MATERIAL AND METHODS: Ten wrists in 10 asymptomatic volunteers (mean age = 29 years) were scanned. Participants underwent 3-T MRI using the harness and flexible glove coil, acquiring sagittal turbo spin echo (TSE) and half-Fourier acquisition single-shot turbo spin echo (HASTE) pulse sequences. Static TSE images were obtained in neutral, extended, and weightbearing positions using proton density parameters and independently evaluated by two radiologists for: dorsal radiocarpal ligament thickness; radiocapitate, radiolunate, and capitatolunate angles; palmar translation of the lunate on the radius; angulation of the extensor tendons; and distance from the distal extensor retinaculum to Lister's tubercle. Cine HASTE images were dynamically acquired between neutral-maximum extension to measure the radiocapitate angle. RESULTS: Good reader agreement was observed (r > 0.73) for all measurements except palmar translation in the neutral position (r = 0.27). Significant increases in dorsal radiocarpal ligament thickness; radiocapitate, radiolunate and capitolunate angulation; and extensor tendon angulation were observed between the neutral and extended positions (P < 0.001). A further significant increase in these metrics between extended and weightbearing positions was also seen (P < 0.01). CONCLUSION: Significant increases in dorsal radiocarpal ligament thickness, articular and tendon angulations occur during wrist extension, that further increase with dorsal weightbearing.

Trapezoid Stress Fracture in a Competitive Baseball Player.

Isolated fractures of the trapezoid are an exceedingly rare injury, and stress fractures of the carpus are similarly uncommon. An 18-year-old competitive baseball player presented with atraumatic, progressive hand pain. He was found to have a stress fracture of the trapezoid. Symptoms resolved with rest and immobilization.

Clinical utility of portable versus traditional electrodiagnostic testing for diagnosing, evaluating, and treating carpal tunnel syndrome.

Data indicate that a portable electrodiagnostic device (NC-Stat; Neurometrix, Inc, Cambridge, Mass) provides objective preoperative evidence of the severity of median nerve dysfunction as well as useful objective postoperative data. With traditional electrodiagnostic studies for comparison, we studied the utility of this device as a diagnostic tool, evaluated patient satisfaction with the instrument, and found statistically significant improvement in recorded distal motor latency at 6-month follow-up. Such data can be of great value in treating a patient who does not exhibit subjective symptom improvement. This portable electrodiagnostic device provides a reliable, convenient, and relatively inexpensive way to obtain objective data that can be used in diagnosing, evaluating, and treating carpal tunnel syndrome.

Capitellum fractures: a biomechanical evaluation of three fixation methods.

OBJECTIVE: To determine the relative stability of three fixation methods for displaced capitellum fractures. DESIGN: Twelve matched pairs of embalmed humeri were divided into two equal groups and simulated capitellum fractures created. The first group compared cancellous lag screws placed in an anteroposterior direction to screws placed in the posteroanterior direction. The second group compared the Acutrac compression screw, inserted anteroposteriorly, to the more stable construct from the first test group. METHODS: All specimens were cyclically tested with simulated physiologic loading. Both displacement of the capitellum over a range of cycles and the number of cycles to failure were recorded. RESULTS: Fixation with posteroanteriorly directed cancellous lag screws was significantly more stable than anteroposteriorly directed screws at 2000 cycles (p = 0.007); loads to failure were not statistically different. Fixation by the Acutrac screws was significantly more stable than posteroanterior cancellous screws at 2000 cycles (p = 0.03). The Acutrac fixation had a higher failure load; however, this was not statistically significant. CONCLUSION: The headless screws tested in this biomechanical study provided more stable fixation of capitellum fractures in the cadaveric specimens than four-millimeter partially threaded cancellous lag screws and may do so in the clinical setting. When the cancellous lag screws were tested, insertion in the posteroanterior direction provided more stable fixation than the anteroposterior direction and has clinical benefit of not violating the articular surface. Ultimately, the decision of which method to use lies with the attending surgeon and the technique with which he or she feels most comfortable.

Comparison of two headless screw designs for fixation of capitellum fractures.

In order to determine the effects of two different headless screw designs on fixation of simulated capitellum fractures six matched pairs of embalmed humeri had simulated capitellum fractures created. Fixation with Acutrac compression screws was compared to Herbert screws in a matched pair experimental design. All specimens were cyclically tested with simulated physiologic loading. Both displacement of the capitellum as a function of the number of cycles and failure loads were determined. Fixation by the Acutrac screws was significantly more stable than Herbert screws at 2000 cycles, 0.17 mm wersus 1.57 mm (p < 0.02) The Acutrac fixation also had a higher failure load, 154 N versus 118 N (p < 0.05). The Acutrac screws tested in this biomechanical study provided more stable fixation of simulated capitellum fractures than Herbert screws. This appears to be related to the design of these screws.