Effects of partial wrist arthrodesis on loading at the radiocarpal joints

The radiocarpal joint plays an important role in the stabilization of the wrist joint. Degenerative diseases such as rheumatoid arthritis can destabilize the joint and compromise the kinematics of the carpal bones. Partial wrist arthrodesis in the rheumatoid wrist has been popular since its introduction in 1983 [1]. The procedure prevents ulnar drift of the carpus and prevents progression to a subluxed state as well as providing pain relief for the patient. The biomechanical consequences of arthrodesis at the radiocarpal joint have not been extensively explored. This study looks at the biomechanical changes on the load transfer through the radiocarpal joint after partial wrist fusion

Treatment of Scaphoid Non-Unions with Custom-Made 3D-Printed Titanium Partial and Total Scaphoid Prostheses and Scaphoid Interosseous Ligament Reconstruction

Purpose: Treatment of scaphoid fracture sequelae is still an unsolved problem in hand surgery. Custom-made 3D-printed titanium partial and total scaphoid prosthesis and scaphoid interosseous ligament reconstruction (SLIL) are performed in cases of non-union and isolated aseptic necrosis of the proximal scaphoid pole and when it is impossible to save the scaphoid bone, respectively. This study aims to evaluate the clinical, functional and radiographic results after these two prosthesis implantations. Methods: Between January 2019 and July 2020, nine partial and ten total scaphoid prostheses were implanted using custom-made 3D-printed titanium implants. Evaluation criteria included carpal height ratio (CHR), radioscaphoid angle, wrist extension and flexion, radial deviation and ulnar deviation of the wrist, grip strength and pinch strength, Visual Analogue Scale (VAS), the Disabilities of Arm, Shoulder, and Hand (DASH) score, and the Patient-Rated Wrist Evaluation (PRWE). Results: Clinical, functional, and radiographic improvements were found in all outcomes analyzed for both patient groups. The VAS pain scale obtained the most remarkable improvement at the one-year follow-up. The results of the DASH scores and the PRWE were good, with a great rate of patient satisfaction at the end of the follow-up. SLIL reconstruction also provided excellent stability and prevented a mid-carpal bone collapse in the short- and medium-term follow-up. Conclusions: A custom-made 3D-printed titanium partial or total scaphoid prosthesis is a viable solution for patients with scaphoid non-union and necrosis or complete scaphoid destruction in whom previous conservative or surgical treatment has failed

Geometric and Mechanical Characterization of Human Carpal Bones – a Preliminary Study

Human hand injuries account for a significant number of accidents of young adults (mostly sports injuries) and elderly people. The most vulnerable part of the hand is the wrist, a construct consisting of numerous bones and ligaments. The hand is a complex structure, the mechanical behavior is hard to describe, and also it is sometimes hard to correctly diagnose the injuries. The goal of the present research is to create a quickly and inexpensive measurement method to characterize the geometrical and mechanical properties of carpal bones.The method presented is suitable to properly characterize the intact and damaged geometries of different carpal bones (capitate scaphoid, trapezium, pisiform). 3D models of intact and failed bones are determined by a 3D scanner, mechanical properties are determined with high-speed compression load (700 mm/min), which represents the fracture by falling down. According to the test results, the 3D scanning technique provided valuable geometrical data for cross-section calculation (scan before the test) and for analysis of the failure mode of the bones (scan after the test). The modulus of elasticity data for finite element simulation can be determined by the high-speed compression tests

Ulnar-sided wrist pain. II. Clinical imaging and treatment

Pain at the ulnar aspect of the wrist is a diagnostic challenge for hand surgeons and radiologists due to the small and complex anatomical structures involved. In this article, imaging modalities including radiography, arthrography, ultrasound (US), computed tomography (CT), CT arthrography, magnetic resonance (MR) imaging, and MR arthrography are compared with regard to differential diagnosis. Clinical imaging findings are reviewed for a more comprehensive understanding of this disorder. Treatments for the common diseases that cause the ulnar-sided wrist pain including extensor carpi ulnaris (ECU) tendonitis, flexor carpi ulnaris (FCU) tendonitis, pisotriquetral arthritis, triangular fibrocartilage complex (TFCC) lesions, ulnar impaction, lunotriquetral (LT) instability, and distal radioulnar joint (DRUJ) instability are reviewed

The scaphoid : from fracture to fusion

In paper I, the incidence, treatment approaches, and rates of nonunion in scaphoid fractures were examined using data from 34,377 patients recorded in the Swedish National Patient Register (NPR) between 2006-2015. The accuracy of NPR data was confirmed through validation involving 300 patients, revealing that approximately 41% of diagnosed scaphoid fractures were false positives. The overall incidence rate was found to be around 22 per 105 person-years. Median age was 26 years and 69% of the patients were men. 5% of the patients were operated and 2% developed scaphoid nonunion. Paper II evaluated the outcomes of scaphoid nonunion surgery in 63 patients in a retrospective study with a mean follow-up of 7 years. Patients were divided into two groups: those with residual deformity and those without. The calculation of scaphoid deformity was based on computed tomography (CT) scans, comparing the heightlength (H/L) ratio of the operated scaphoid to that of the uninjured one. There were no significant differences between the two groups in Disabilities of the Arm, Shoulder and Hand score (DASH), Patient-Rated Wrist Evaluation score (PRWE), wrist range of motion (ROM), and grip strength. Wrist extension was slightly worse in the deformity group. In paper III, we analyzed the direct motion between the scaphoid and lunate during the dart-throwing motion (DTM) in vivo with a volume registration technique (computed tomography based micromotion analysis, CTMA). We found motion between the scaphoid and lunate, including translation and rotation and that scapholunate ligament injury leads to increased motion. Paper IV was a pragmatic randomized controlled trial (RCT) which compared lunocapitate fusion (LCF) and four-corner fusion (4CF) as surgical treatments for scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC). There was only a small improvement in grip strength with no clinically significant difference between the two treatment groups. No differences between groups were found in DASH, PRWE, European quality of life-5 dimensions-3 level (EuroQol-5D-3L), wrist ROM, key pinch strength, and complications at 12 months postoperatively. In paper V we examined seven patients who had undergone LCF at least one year before. CT scans were performed in maximal radial extension and maximal ulnar flexion. Using CTMA, motion of the triquetrum was analyzed compared to the contralateral side. Triquetral movement was observed in all patients but significantly less than in the nonsurgical wrist. There also was minor motion between the hamate and fused lunocapitate bones. In conclusion, Scaphoid fractures primarily occur in young males, and the risk of developing a nonunion after such a fracture is relatively low. Residual scaphoid deformity has no relevant negative impact on mid-term wrist function. There is scapholunate motion during DTM and caution should be taken when implementing dart-throwing exercises during early rehabilitation after scapholunate repair surgery. LCF is not inferior to 4CF in terms of strength, range of motion or patient-reported outcome measures. Triquetral motion is limited after lunocapitate arthrodesis

Mechanical assessment of two hybrid plate designs for pancarpal canine arthrodesis under cyclic loading

Pancarpal canine arthrodesis (PCA) sets immobilization of all three carpal joints via dorsal plating to result in bony fusion. Whereas the first version of the plate uses a round hole (RH) for the radiocarpal (RC) screw region, its modification into an oval hole (OH) in a later version improves versatility in surgical application. The aim of this study was to mechanically investigate the fatigue life of the PCA plate types implementing these two features–PCA-RH and PCA-OH. Ten PCA-RH and 20 PCA-OH stainless steel (316LVM) plates were assigned to three study groups (n = 10). All plates were pre-bent at 20° and fixed to a canine forelimb model with simulated radius, RC bone and third metacarpal bone. The OH plates were fixed with an RC screw inserted either most proximal (OH-P) or most distal (OH-D). All specimens were cyclically tested at 8 Hz under 320 N loading until failure. Fatigue life outcome measures were cycles to failure and failure mode. Cycles to failure were higher for RH plate fixation (695,264 ± 344,023) versus both OH-P (447,900 ± 176,208) and OH-D (391,822 ± 165,116) plate configurations, being significantly different between RH and OH-D, p = 0.03. No significant difference was detected between OH-P and OH-D configurations, p = 0.09. Despite potential surgical advantages, the shorter fatigue life of the PCA-OH plate design may mitigate its benefits compared to the plate design with a round radiocarpal screw hole. Moreover, the failure risk of plates with an oval hole is increased regardless from the screw position in this hole. Based on these findings, the PCA plate with the current oval radiocarpal screw hole configuration cannot be recommended for clinical use