Scaphoid tuberosity excursion is minimized during a dart-throwing motion: A biomechanical study.

PURPOSE: The purpose of this study was to determine whether the excursion of the scaphoid tuberosity and therefore scaphoid motion is minimized during a dart-throwing motion. METHODS: Scaphoid tuberosity excursion was studied as an indicator of scaphoid motion in 29 cadaver wrists as they were moved through wrist flexion-extension, radioulnar deviation, and a dart-throwing motion. RESULTS: Study results demonstrate that excursion was significantly less during the dart-throwing motion than during either wrist flexion-extension or radioulnar deviation. CONCLUSION: If the goal of early wrist motion after carpal ligament or distal radius injury and reconstruction is to minimize loading of the healing structures, a wrist motion in which scaphoid motion is minimal should reduce length changes in associated ligamentous structures. Therefore, during rehabilitation, if a patient uses a dart-throwing motion that minimizes his or her scaphoid tuberosity excursion, there should be minimal changes in ligament loading while still allowing wrist motion. STUDY DESIGN: Bench research, biomechanics, and cross-sectional. LEVEL OF EVIDENCE: Not applicable. The study was laboratory based.

The Effect of Scaphoid Fracture Site on Scaphoid Instability Patterns.

Background Scaphoid fractures are common carpal fractures that are often misdiagnosed as wrist sprains and may go on to nonunion. The location of the fracture site may influence the stability of scaphoid nonunions. Purpose To determine whether the stability of a scaphoid nonunion depends upon the fracture's location, we tested the hypothesis that a simulated fracture distal to the apex of the scaphoid dorsal ridge will have greater interfragmentary motion than proximal. Methods Eleven cadaver wrists were moved through three wrist motions using a wrist simulator. In six wrists, a fracture was created distal to the scaphoid apex, and in five a fracture was created proximal to the apex. Sensors attached to the distal and proximal parts of each scaphoid measured the interfragmentary motion during wrist motion. Results In those wrists in which the scaphoid was sectioned distal to the apex, the distal fragment became significantly more unstable relative to the proximal fragment. It flexed, ulnarly deviated, and pronated. These motion changes were less when the scaphoid was sectioned proximally. Discussion Scaphoid fractures distal to the scaphoid apex will have greater interfragmentary motion. The mobility of the fragments at the fracture site is possibly a more important contributory factor of nonunion in scaphoid waist fractures than for proximal scaphoid fractures. Clinical Relevance Understanding the effect that the location of a scaphoid fracture has on the potential for nonunion may influence the modalities of treatment and follow-up.

Decreasing the pain of finger block injection: level II evidence.

BACKGROUND: There is level II evidence that volunteers prefer the single subcutaneous injection in the midline of the proximal phalanx with lidocaine and epinephrine (SIMPLE) finger block over the classic two dorsal injection block technique. The purpose of this study was to possibly further decrease the pain of digital block injection by examining the effect of the duration of injection on the pain felt by volunteers receiving the SIMPLE block at two different injection rates. METHODS: Forty healthy blinded volunteers were injected 2 mL of lidocaine 1 % and epinephrine 1/100,000 in the digital palmar crease of both long fingers, one at a time. Two different rates of injection were used: 8 and 60 s. Pain scores were measured using a visual analogue scale and the volunteers were asked which of injection techniques they preferred. RESULTS: The visual analogue scale results revealed less pain with the slow injection (p < 0.001). Thirty three out of 40 volunteers preferred the slow injection rate. No difference could be attributed to sex of participants or to the first hand injected. CONCLUSION: Blinded volunteers preferred digital blocks injected over 60 s to the more rapid 8 s. Decreasing the pain of injection only takes a minute of our valuable time for finger blocks.