Zong-Ping Luo

Management of the scaphoid during four-corner fusion-a cadaveric study.

PURPOSE To examine the effects of scaphoid retention, inclusion, and excision on wrist motion and radiolunate contact characteristics in a cadaveric model after simulated 4-corner fusion with rigid internal fixation. METHODS Seven fresh-frozen cadaveric upper extremities were examined. For all surgical manipulations the motion was measured and contact characteristics were assessed using ultra-low prescale pressure-sensitive film. RESULTS Compared with the intact specimen, simple 4-corner fusion with scaphoid retention led to a significant decrease in extension, radial deviation, and ulnar deviation, but no change in radiolunate contact characteristics. After 4-corner fusion there was no significant difference in motion or radiolunate contact characteristics between scaphoid retention and scaphoid inclusion. After 4-corner fusion scaphoid excision allowed significantly greater radial deviation compared with scaphoid retention and scaphoid inclusion. Compared with the intact specimen 4-corner fusion with scaphoid excision also led to a significant increase in radiolunate contact area and mean contact pressure. CONCLUSIONS When performing 4-corner arthrodesis in the absence of radioscaphoid arthritis, scaphoid excision may improve motion at the cost of increased mean radiolunate contact pressure.

The Origins of the Thenar and Hypothenar Muscles

This paper presents an anatomical study of the origins of the thenar and hypothenar muscles and postulates the causes of weakness and pillar pain following carpal tunnel release.

Mechanical Strain Promotes Fibroblast Gene Expression in Presence of Corticosteroid

Posterior tibial tendon (PTT) dysfunction has commonly been treated with local corticosteroid injections to reduce inflammation. However, a concern with this treatment is potential degeneration and spontaneous rupture of the PTT. This study set out to determine whether mechanical strain may counteract the potentially deleterious effect of corticosteroid treatment on fibroblasts and therefore improve outcomes during recovery from tendinitis. In this study, PTT fibroblasts in vitro were treated with 0 M, 10−7 M, 10−6 M, and 10−5 M triamcinolone acetonide (TA) while incubated under cyclic strains of 0% or 5% for 24 hr. Type I collagen and decorin mRNA expressions were determined by RT-PCR. The results indicated that mechanical strain significantly increased type I collagen and decorin gene expression in the PTT fibroblasts and TA decreased type I collagen and decorin gene expression. Therefore, mechanical strain might be beneficial to PTT after corticosteroid treatment by direct stimulation of fibroblast synthesis.

Initiatory biomechanical study on humeral head migration after coracoacromial ligament cut

ObjectTo design and evaluate the strength of muscles in preventing humeral head migration after acromioplasty by biomechanical research on cadaver models.MethodsSix fresh shoulder cadavers were studied. The coracoacromial ligament cut model was prepared in five shoulders for the study. Different forces were applied to the head of humerus with designed strengthened force on rotator cuff muscles. The results were calculated with SPSS software.ResultsThe anterior and superior pulling force caused obvious migration of humeral head in coracoacromial ligament cut model; after strengthening the rotator cuff muscles, especially the supraspinatus and subscapular muscle, the humeral head migration was reduced.ConclusionModified acromioplasty with supraspinatus and subscapular muscle, strengthened in our experiment, helped to control the migration of humeral head.

A Modified Cell Culture Method for Autologous Chondrocyte Transplantation

Autologous chondrocyte transplantation (ACT) is a promising method to treat chondral and osteochondral defects. This study introduced a modified method for cell culture in ACT. Porcine chondrocytes were cultured for 3 weeks under low hydrostatic pressure at 250 Pa. The results showed that the dry weight of the cartilage-like membrane in the loading group was 3.0 times more than the control group (no loading) (p < 0.01), and cell numbers were significantly increased by 3.1 times (p < 0.01) after a 3-week culture. Compared with the fresh tissue sample, the mRNA expression of collagen II was not statistically different and the mRNA of aggrecan was only slightly decreased by 19%. These data suggest that the hydrostatic pressure at this level significantly increased the cell numbers and biosynthesis of cultured chondrocytes.

A method for testing compressive properties of single proteoglycan aggregates

This study presents a method for direct measurement of the compressive properties of single molecules of proteoglycan aggregate using a state-of-the-art laser tweezers/interferometer system previously developed to test the tensile properties of single molecules. A typical molecule of proteoglycan aggregate showed a highly non-linear resistance to compression after being compressed to about 25% of its original molecule length.