Biomechanical comparison of C1-C2 posterior arthrodesis techniques.

Study Design: Biomechanical comparison of 5 atlantoaxial posterior arthrodesis techniques.

Objective: To assess the relative value of different posterior wire constructs when one or two transarticular screws are used.

Summary Of Background Data: A combination of Gallie or Brooks techniques and 2 posterior transarticular screws has been shown to be effective for atlantoaxial arthrodesis.

Medial collateral ligament strain with partial posteromedial olecranon resection. A biomechanical study.

Background: Partial resection of the posteromedial aspect of the olecranon in the treatment of valgus extension impingement osteophytosis is a well-described technique. It has been hypothesized that removal of the normal olecranon process, beyond the osteophytic margin, increases the strain in the anterior bundle of the medial collateral ligament.

Methods: We used an electromagnetic tracking device to investigate the strain in the anterior bundle of the medial collateral ligament as a function of increasing applied torque and posteromedial resections of the olecranon in seven cadaveric elbows.

The noncircular shape of the radial head.

Purpose: The purpose of this study was to define the shape of the radial head by identifying the relationship between precisely defined axes of the radial head.

Methods: An anatomic study was done to define the shape of the radial head and specifically the relationship between the long and the short axis. Twenty-seven cadaveric upper extremities were used.

Kinematics and functional characteristics of the Pritchard ERS unlinked total elbow arthroplasty.

This study examined the kinematic characteristics of the Pritchard ERS elbow-resurfacing system, with special attention paid to the effects of the radial head component. The kinematics between the ulna and humerus were assessed in 6 human cadaveric specimens by an electromagnetic tracking system throughout a full flexion/extension range of motion. The elbows were studied under 2 loading conditions, in 3 orientations (neutral, varus, and valgus), and under 4 surgical conditions.

Kinematic and torque-related effects of dorsally angulated distal radius fractures and the distal radial ulnar joint.

Purpose: The purpose of this study was to examine the torque required to achieve a full range of motion of the distal radioulnar joint (DRUJ) as a result of increasing dorsal angulation from simulated fractures of the distal radius. Based on this study the accepted amount of dorsal angulation of the distal radius can be determined.

Methods: In 9 fresh cadaver limbs motion of the DRUJ was simulated by a custom motion and loading forearm device.

Biomechanical evaluation of new posterior occipitocervical instrumentation system.

Twelve fresh-frozen cadaveric occipitocervical specimens were randomized based on dual energy xray absorptiometry analysis of bone mineral density. The specimens were subjected to physiologic loads in a device that applied pure unconstrained flexion and extension, lateral bending, and axial rotational moments. The spines were tested intact and after major injury simulating transoral decompression of the dens.

Biomechanical evaluation of posterior screw fixation in cadaveric cervical spines.

Sixteen fresh-frozen spines from cadavers (C4-T1) were randomized on the basis of dual energy xray absorptiometry analysis of bone mineral density. The specimens were subjected to physiologic loads ( View Article and Find Full Text PDF

Dynamic stabilizing function of the deltoid muscle in shoulders with anterior instability.

Background: The stabilizing role of the deltoid muscle has not been extensively studied.

Purpose: To study the contribution of the deltoid muscle to anterior stability of the shoulder.

Study Design: Controlled laboratory study.

Importance of a radial head component in Sorbie unlinked total elbow arthroplasty.

The effects of a radial head component on total elbow arthroplasty kinematics and stability were evaluated using an anatomic design unlinked total elbow prosthesis. An electromagnetic tracking device recorded motion and varus and valgus displacements under various conditions in 10 cadaveric elbows. The motion patterns of the intact elbows and the Sorbie-Questor total elbow prostheses with a radial head component were similar, as both tended to have a valgus position in extension, varus at midflexion, and more valgus toward full flexion.

Analysis of dynamic distal radioulnar convergence after ulnar head resection and endoprosthesis implantation.

The most common method to treat the arthralgic distal radioulnar joint is resection of the entire ulnar head (Darrach procedure). Pain and weak grip strength usually manifest complications related to instability of the distal forearm. In an attempt to mechanically stabilize the distal forearm after ulnar head resection, an endoprosthesis was developed to replace the ulnar head after Darrach resection.

An analysis of the constraint properties of the distal radioulnar ligament attachments to the ulna.

Nine cadaver upper extremities were tested to evaluate the constraint properties of the dorsal and palmar radioulnar ligaments at their foveal and styloid attachments to the ulna. The specimens were tested by anterior and posterior displacement of the radius relative to the ulna with the forearm in pronation, supination, and neutral rotation. There were no statistically significant differences in the relative percent of constraint contribution of the styloid and foveal ligament insertions.