vendex and Arthritis

Diagnostic and rehabilitative assessments of hand function commonly omit measurement of twisting strength even though many activities of daily living require turning handles, lids, and objects of many sizes. A simple device to quantify twisting strength was designed and constructed to establish normative data and test hypotheses about hand function. The instrument is easy to use and includes an electronic torsional load cell and disks of several sizes. Tests were conducted on the dominant and nondominant hands of 64 normal subjects and 13 arthritic patients with arthritis of the thumb carpometacarpal joint. Hands were tested with disks ranging in diameter from 2.5 to 12.5 cm. A three-way repeated measures analysis showed that gender (p < 0.001), handedness (p < 0.001), and disk size (p < 0.001) had significant effects. There was no difference between radial and ulnar deviation strengths (p = 0.365). The arthritic group had significantly reduced strength (p < 0.02). Nine subjects were tested twice, with 1 day between tests: no differences occurred between the first and second testing (p = 0.930). The ability to distinguish the test groups with reproducible results proves that the device fulfills all basic requirements; continued testing and development are warranted.

Topics: Adult; Aged; Arthritis; Biomechanical Phenomena; Equipment Design; Equipment Failure Analysis; Exercise Test; Female; Hand; Hand Strength; Humans; Male; Middle Aged; Muscle Contraction; Physical Examination; Torque; Transducers; Wrist

Midcarpal arthrodesis is a treatment of choice in patients with midcarpal arthritis. Traditionally a four corner fusion has been favoured, however recent research has shown improved results when the triquetrum and scaphoid are excised. There is no clear evidence as to which remaining bones should be fused or which implants should be used. The purpose of this study is to compare the biomechanics of midcarpal arthrodesis after scaphoid and triquetrum excision, using memory staples or cannulated screws, in recognised construct patterns.. 36 identical sets of carpal bones were 3D printed from acetyl butyl styrene. Midcarpal arthrodeses were performed in three configurations with shape memory alloy staples or headless compression screws. This gave 6 treatment groups; lunocapitate single staple or screw, lunocapitate with 2 staples or screws, three corner fusion with 2 staples or screws. Peak torque to distraction was measured and analysed.. The peak torque to distraction was significantly greater in almost all constructs utilizing screws compared to staples, with two lunocapitate screws having the highest peak torque at both 1 and 3 mm distraction with 244 Nmm and 749 Nmm respectively (p < 0.05).. Constructs utilizing screws have a peak torque to distraction significantly higher when compared to staples. Our recommendation when performing a midcarpal arthrodesis after scaphoid and trapezium excision is to fuse the midcarpal joint with 2 headless compression screws.

Topics: Arthritis; Arthrodesis; Bone Screws; Carpal Bones; Humans; Models, Anatomic; Printing, Three-Dimensional; Surgical Stapling; Torque

The overexpression of tumor necrosis factor (TNF)-α leads to systemic as well as local loss of bone and cartilage and is also an important regulator during fracture healing. In this study, we investigate how TNF-α inhibition using a targeted monoclonal antibody affects fracture healing in a TNF-α driven animal model of human rheumatoid arthritis (RA) and elucidate the question whether enduring the anti TNF-α therapy after trauma is beneficial or not.. A standardized femur fracture was applied to wild type and human TNF-α transgenic mice (hTNFtg mice), which develop an RA-like chronic polyarthritis. hTNFtg animals were treated with anti-TNF antibody (Infliximab) during the fracture repair. Untreated animals served as controls. Fracture healing was evaluated after 14 and 28 days of treatment by clinical assessment, biomechanical testing and histomorphometry.. High levels of TNF-α influence fracture healing negatively, lead to reduced cartilage and more soft tissue in the callus as well as decreased biomechanical bone stability. Blocking TNF-α in hTNFtg mice lead to similar biomechanical and histomorphometrical properties as in wild type.. High levels of TNF-α during chronic inflammation have a negative impact on fracture healing. Our data suggest that TNF-α inhibition by an anti-TNF antibody does not interfere with fracture healing.

Topics: Animals; Antibodies, Monoclonal; Arthritis; Arthritis, Rheumatoid; Bone Nails; Bony Callus; Disease Models, Animal; Female; Femoral Fractures; Fracture Fixation, Internal; Fracture Healing; Humans; Inflammation; Infliximab; Mice; Mice, Transgenic; Stress, Mechanical; Torque; Tumor Necrosis Factor-alpha; Weight-Bearing

It is far from clear how best to define the proper strength of soft-tissue tensioning in total knee arthroplasty (TKA). We attached a torque driver to the Monogram balancer/tensor device and measured soft-tissue tension in full extension and 90 degrees flexion during TKA. In our surgical procedure, when we felt proper soft-tissue tension was being applied, the mean distraction force was noted to be 126N in extension and 121N in flexion. There was no significant correlation between soft-tissue tension and the postoperative flexion angle finally achieved. To the best of our knowledge, this is the first study to assess the actual distraction forces in relation to soft-tissue tension in TKA. Further study may reveal the most appropriate forces to achieve proper soft-tissue tension in the wide variety of circumstances presenting at knee arthroplasty.

Topics: Adult; Aged; Aged, 80 and over; Arthritis; Arthroplasty, Replacement, Knee; Female; Humans; Male; Middle Aged; Statistics, Nonparametric; Surgical Instruments; Torque; Treatment Outcome

Resection of the entire ulnar head (Darrach operation) and the hemiresection interposition arthroplasty are common methods of treating the arthritic distal radioulnar joint (DRUJ). Biomechnical investigation about both of these procedures is lacking. The purpose of this study was to evaluate the dynamic effects of both the hemiresection interposition arthroplasty and the Darrach procedure on radioulnar convergence and dorsal-palmar displacement and to compare their biomechanical behaviours. With a dynamic computer-controlled testing device, cadaveric forearm rotation was performed with simultaneous loading of relevant muscles. Torque along the forearm axis was generated by simulated muscle action through pneumoactuators attached to relevant tendons while the wrist was constrained to prescribed ranges of motion. The instability of the radius relative to the ulna was evaluated using displacement data of digitized landmarks in an ulnar coordinate system. Seven fresh-frozen cadaver upper extremities were used. The Darrach resection created an extreme instability of the forearm with movement of the radius ulnarly. Anteroposterior translations in each loading condition could also be detected, but the magnitude of displacement was small and less predictable. The results of the hemiresection interposition arthroplasty demonstrated significantly less instability compared with the Darrach results.

Topics: Aged; Arthritis; Arthroplasty; Biomechanical Phenomena; Female; Humans; In Vitro Techniques; Joint Instability; Male; Middle Aged; Radius; Range of Motion, Articular; Torque; Weight-Bearing; Wrist Joint