Transtrapezial Approach for Fixation of Acute Scaphoid Fractures: Rationale, Surgical Techniques, and Results: AAOS Exhibit Selection

Comparison of conventional and transtrapezial palmar approaches for screw fixation of scaphoid waist fractures: a clinical study

We investigated two palmar approaches for screw fixation of acute scaphoid waist fractures: the conventional percutaneous or transtrapezial approach. Thirty cases who underwent operation from 2013 to 2021 were reviewed (conventional group, 15; transtrapezial approach group, 15). Cross-sections were constructed along the long axis of the scaphoid on postoperative computed tomography to evaluate the screw position, relative to the centre point in the distal-third, midwaist and proximal-third of the bone. The screw could be inserted centrally in the proximal and distal regions using the transtrapezial approach. In the conventional approach, the screw was inserted radially in the distal region, but tended to be positioned centrally in the midwaist and proximal regions. As central placement of the screw in the proximal fragment offers a biomechanical advantage, both approaches can be options for some fracture patterns, while for others, the fracture pattern could influence which approach is better.Level of evidence: IV.

Scaphoid Fractures in Athletes

Scaphoid fractures are common injuries in athletes. Most can be treated with cast immobilization, with an expected rate of union of 90% to 95%. Cast treatment, however, has the disadvantages of longer immobilization time, joint stiffness, reduced grip strength, and longer time to return to manual work or athletics. Closed reduction and percutaneous screw fixation generally are preferred in athletes to allow a quicker return to sport; if closed reduction cannot be obtained, open reduction and internal fixation may be required.

Deviations in positioning variable pitch screws- scaphoid waist fractures

INTRODUCTION

Operative therapy using a headless cannulated variable pitch compression screw is the gold standard for the treatment of instable scaphoid fractures.

HYPOTHESIS

Deviation from the central placement is associated with a loss of stability and stiffness.

MATERIAL AND METHODS

An artificial bone model was manufactured and different screw positions (central, 10° and 20° to the long axis) were assessed. A shearing test with axial force on the 45° flexed scaphoid was applied.

RESULTS

The inserted variable pitch screw showed the highest stiffness and failure force in a position in the long axis. At 10 degrees, a slight decrease in stiffness (32.7N/mm±9.3N/mm) and failure force (41.6N±13.2N) was observed, while a significant reduction in stiffness (29.3N/mm±4.6N/mm) and failure force (50.3N±19.5N) was measured at 20 degrees.

DISCUSSION

Deviations in the angle of insertion of the compression screw cause loss in failure force, thus deviations from the central placement is associated with less stability and stiffness.

LEVEL OF PROOF

Controlled laboratory study (basic science study, biomechanical testing).

Approach to the Perpendicular Fixation of a Scaphoid Waist Fracture-A Computer Analyzed Cadaver Model

PURPOSE

In scaphoid fracture screw fixation, the screw is commonly placed along the long axis of the bone, without consideration of the fracture plane. This position is not perpendicular to transverse waist fractures or to the more common horizontal oblique fractures. Our aim was to examine the feasibility and describe possible approaches to, placing a screw perpendicular and in the center of the scaphoid waist fracture.

METHODS

Computed tomography of 12 cadaver wrists was performed in 3 positions to examine possible approaches in flexion, neutral, and extension of the wrist. The scans were evaluated using a 3-dimensional model that simulated horizontal oblique (60°) and transverse (90°) fractures. We examined all possible approaches for screw positioning and their deviation from the axis perpendicular to the fracture and in the center of its plane.

RESULTS

The preferred approaches for a perpendicular screw in a horizontal oblique fracture were found to be proximal-dorsal in flexion or transtrapezial in the extended or neutral positions (through the volar-radial trapezium). In transverse fractures, the possible approaches were proximal-dorsal or transtrapezial in the flexed or neutral positions and distal in the extended position (volar to volar-radial trapezium). In these approaches, the screw could be placed perpendicularly (deviating by < 10°) and in the center of the fracture in all specimens.

CONCLUSIONS

According to this model, it appears feasible to place a perpendicular screw in the center of a horizontal oblique waist fracture using a proximal-dorsal approach in flexion or a transtrapezial approach in neutral or extension positions of the wrist. Palpable landmarks may be used as additional guides to direct these approaches according to the clinical setting.

CLINICAL RELEVANCE

Perpendicular screw fixation of horizontal oblique or transverse scaphoid waist fractures is a possible option, if chosen for its biomechanical advantages.

Transtrapezial Approach for Fixation of Acute Scaphoid Fractures

Introduction

The transtrapezial approach for fixation of acute scaphoid fractures facilitates precise percutaneous placement of a screw along the central axis of the scaphoid, which has been shown to be biomechanically superior.

Step 1 Position the Patient Surgeon and Fluoroscopy Equipment

Correctly position the patient, surgeon, and fluoroscopy equipment before starting the procedure.

Step 2 Mark the Skin

Mark the central axis of the scaphoid on the skin along the anteroposterior and lateral (optional) planes as the markings allow visual control for insertion of the guidewire.

Step 3 Stab Incision

Make a volar stab incision over the distal half of the trapezium.

Step 4 Insert the Guidewire

Insert the guidewire through the trapezium along the central axis of the scaphoid, which is the critical step of the procedure.

Step 5 Drilling

Drill the trapezium and the distal cortex of the scaphoid to allow easy insertion of the screw.

Step 6 Length Measurement

Precisely measure the scaphoid length to determine the appropriate screw length.

Step 7 Insert the Screw

Insert the selected screw over the guidewire.

Results

In our report on the first results of this technique in forty-one patients with an acute nondisplaced scaphoid waist fracture, all fractures united within ten weeks (mean, 6.4 weeks) and the modified Mayo wrist score was good (four patients) or excellent (thirty-seven patients) at a mean follow-up of thirty-six months (range, fourteen to sixty-eight months).IndicationsContraindicationsPitfalls & Challenges.