Load transfer at the distal ulna following simulated distal radius fracture malalignment

Distal radius fracture volar locking plate osteosynthesis using wide-awake local anaesthesia

Surgical fixation of distal radius fractures under local anaesthesia with the patient wide awake allows an intraoperative testing of the fixation stability under active mobilization. We evaluated the feasibility and clinical results of this technique in 45 patients prospectively in two matched comparable groups: wide-awake local anaesthesia no tourniquet and loco-regional anaesthesia. We found that the pain scores during the anaesthetic administration and the surgical procedure were similar in two groups. Ranges of wrist motion and QuickDASH scores were improved significantly in the wide-awake local anaesthesia no tourniquet group at 6 weeks and 3 months and similar at 6 months compared with those receiving loco-regional anaesthesia. Patients in wide-awake local anaesthesia no tourniquet returned to work significantly earlier than the loco-regional anaesthesia group. We conclude that osteosynthesis of distal radius fractures can be safely performed under wide-awake local anaesthesia no tourniquet, leading to no increase in pain level and similar functional outcomes compared with those under loco-regional anaesthesia.Level of evidence: III.

Effect of Radial Neck Length on Joint Loading

Introduction: Load transfer across the radiocapitellar joint of the elbow is poorly understood both in the setting of the native radial head and following radial head arthroplasty. The purpose of this in vitro study was to determine the effects of radial neck length, arm position, and lateral collateral ligament (LCL) repair on radial load.Methods: A uniaxial load cell was implanted into the radial neck of 8 cadaveric specimens that were mounted on an in vitro motion-control simulator and tested (in dependent, varus, and valgus arm orientations) with the native radial neck length and then −4 to +4 mm lengths. Testing was performed with the LCL intact and after sectioning and repair.Results: There was no significant difference between the 2 LCL states (P = .82), and LCL state was not protective of proximal radius overlengthening. Radial loads increased with increasing radial length (P < .001).Discussion and Conclusion: Overlengthening the radial neck resulted in higher compression forces, and underlengthening produced tensile forces, demonstrating that restoration of correct radial length during radial head arthroplasty is important to restore physiologic loading. In the varus position, tensile loading occurred, which may explain clinical problems with ingrowth of uncemented radial head implant stems and dissociation of bipolar implants.

The Effect of Dorsal Angulation on Distal Radioulnar Joint Arthrokinematics Measured Using Intercartilage Distance

Background  The effects of dorsal angulation deformity on in vitro distal radioulnar joint (DRUJ) contact patterns are not well understood. Purpose  The purpose of this study was to utilize intercartilage distance to examine the effects of forearm rotation angle, distal radius deformity, and triangular fibrocartilage complex (TFCC) sectioning on DRUJ contact area and centroid position. Methods  An adjustable implant permitted the creation of simulated intact state and dorsal angulation deformities of 10, 20, and 30 degrees. Three-dimensional cartilage models of the distal radius and ulna were created using computed tomography data. Using optically tracked motion data, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. Results  DRUJ contact area was highest between 10 and 30 degrees of supination. TFCC sectioning caused a significant decrease in contact area with a mean reduction of 11 ± 7 mm ² between the TFCC intact and sectioned conditions across all variables. The position of the contact centroid moved volarly and proximally with supination for all variables. Deformity had a significant effect on the location of the contact centroid along the volar-dorsal plane. Conclusion  Contact area in the DRUJ was maximal between 10 and 30 degrees of supination during the conditions tested. There was a significant effect of simulated TFCC rupture on contact area in the DRUJ, with a mean contact reduction of 11 ± 7 mm ² after sectioning. Increasing dorsal angulation caused the contact centroid to move progressively more volar in the sigmoid notch.

Current Trends in the Management of Distal Radius Fractures

This article discusses recent reports on distal radius fractures. The keyword "distal radius fracture" was used to query the PubMed database of the US National Library of Medicine. From the resulting list, articles published in the Journal of Hand Surgery (American Volume), the Journal of Hand Surgery (European Volume), and the Journal of Orthopaedic Trauma from April 2014 through December 2015 were reviewed. Related commentaries were also evaluated. Case series of fewer than 5 patients were excluded. The 65 studies and commentaries identified are categorized and summarized. [Orthopedics. 2017; 40(3):145-152.].

Relationship Between Ulnar Variance, Cortical Bone Density, and Load to Failure in the Distal Radius at the Typical Site of Fracture Initiation

PURPOSE

Increased ulnar variance has been shown to lead to diminished load borne by the distal radius. The purpose of this study was to determine the correlations among ulnar variance, bone mineral density, and load to failure at the distal radius.

METHODS

Posteroanterior radiographs and computed tomographic scans were taken of 12 cadaveric forearms in neutral rotation. Ulnar variance was measured for each wrist by the method of perpendiculars. Measurements of cortical, trabecular, and combined bone density were made at the distal radius. We performed linear regression analysis and correlation analysis to determine the relationship between bone densities and ulnar variance measurements. Next, we loaded the 12 cadaveric radii to failure under axial compression. Linear regression analysis and correlation analysis were then performed to determine the relationship between load to failure and both ulnar variance and cortical density.

RESULTS

Increased ulnar variance was significantly correlated with decreased cortical bone density at the distal radius and both were correlated with decreased load to failure. We found no correlation between ulnar variance and trabecular density or combined trabecular and cortical bone density at the distal radius.

CONCLUSIONS

Our study found that increased ulnar variance and decreased cortical bone mineral density correlates with decreased load to failure under axial compression.

CLINICAL RELEVANCE

Ulnar variance is linked to both bone quality and load to failure at the distal radius.