Acute coronal plane scaphoid fracture and scapholunate dissociation from an axial load: a case report

Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures

Background  Central and perpendicular (PERP) screw orientations have each been described for scaphoid fracture fixation. It is unclear, however, which orientation produces greater compression. Questions/Purposes  This study compares compression in scaphoid waist fractures with screw fixation in both PERP and pole-to-pole (PTP) configurations. PERP orientation was hypothesized to produce greater compression than PTP orientation. Methods  Ten preoperative computed tomography scans of scaphoid waist fractures were classified by fracture type and orientation in the coronal and sagittal planes. Three-dimensional models of each scaphoid and fracture plane were created. Simulated Acutrak 2 (Acumed, Hillsboro, OR) screws were placed into the models in both PERP and PTP orientations. Engagement length and screw angle relative to the fracture were measured. Compression strength was calculated from the shear area, average density, and angle acuity. Results  The PTP angle between screw and fracture ranged from 36 to 84 degrees. By definition, the PERP screw-to-fracture angle was 90 degrees. Perpendicularity of the PTP screw to the fracture was positively correlated to compression strength. PERP screws had greater compression than PTP screws when the PTP screw-to-fracture angle was < 80 degrees (106 vs. 80 N), but there was no difference in compression when the PTP screw-to-fracture angle was > 80 degrees, approximating the PERP screw. Conclusion  Increasing screw perpendicularity resulted in higher compression when the screw-to-fracture angle of the PTP screw was < 80 degrees. Maximum compression was obtained with a screw PERP to the fracture. The increased compression gained from PERP screw placement offsets the decreased engagement length. Clinical Relevance  These results provide guidelines for optimal screw placement in scaphoid waist fractures.

Coronal Fractures of the Scaphoid: A Review

Coronal (or frontal plane) fractures of the scaphoid are distinctly uncommon. There are few published reports of coronal fractures of the scaphoid. This fracture is often missed on the initial X-ray films. A high index of suspicion should exist when there is a double contour of the proximal scaphoid pole on the anteroposterior X-ray view. A computed tomography scan is integral in making the diagnosis. Early recognition is key in salvaging the scaphoid fracture and in preventing articular damage. Level of Evidence IV. Retrospective case series.

Absorbable scaphoid screw development: a comparative study on biomechanics

BACKGROUND

The scaphoid is critical for maintaining the stability and movement of the wrist joints. This study aimed to develop a new internal fixator absorbable scaphoid screw (ASS) for fixation of the scaphoid waist after fracture and to test the biomechanical characteristics of ASS.

MATERIALS AND METHODS

An ASS was prepared using polylactic acids and designed based on scaphoid measurements and anatomic features. Twenty fractured scaphoid waist specimens were randomly divided into experimental and control groups (n=10/group). Reduction and internal fixation of the scaphoid were achieved with either Kirschner wires (K-wires) or ASS. A moving target simulator was used to test palmar flexion and dorsal extension, with the range of testing (waist movement) set from 5° of palmar flexion to 25° of dorsal extension. Flexion and extension were repeated 2,000 times for each specimen. Fracture gap displacements were measured with a computerized tomography scanning. Scaphoid tensile and bending strengths were measured by using a hydraulic pressure biomechanical system.

RESULTS

Prior to biomechanical fatigue testing, fracture gap displacements were 0.16±0.02 mm and 0.22±0.02 mm in the ASS and K-wire groups, respectively. After fatigue testing, fracture gap displacements in the ASS and the K-wire groups were 0.21±0.03 mm and 1.52±0.07 mm, respectively. The tensile strengths for the ASS and K-wire groups were 0.95±0.02 MPa and 0.63±0.02 MPa, respectively.

CONCLUSION

Fixation using an ASS provided sufficient mechanical support for the scaphoid after fracture.

Coronal fracture of the scaphoid--a case report and literature review

Coronal fracture of the scaphoid is a rare configuration of scaphoid fracture. Only three cases have been found to be reported in English literature. In our case, a 25-year-old man sustained right wrist injury after a fall with an outstretched hand, was suspected of suffering from a scaphoid fracture as shown on the pre-operative plain radiograph. Coronal fracture of the patient's scaphoid was found intra-operatively and was fixed with two headless compression screws in dorsal-to-volar direction. Post-operative outcome was clinically good as patient was symptom-free, and a computed tomography and radiograph showed complete healing of the fracture with no sign of avascular necrosis.

Volarly displaced transscaphoid, translunate, transtriquetrum fracture of the carpus: case report

A 16-year-old girl sustained a transscaphoid, translunate, transtriquetrum volarly displaced fracture due to shear stress in the coronal plane. Treatment involved open reduction and internal fixation of the fractures followed by immobilization. At 15 months' follow-up, grip strength and motion were diminished compared with the uninjured wrist. Radiographs demonstrated fully healed fractures with narrowing of the cartilage space between the capitate and the lunate.