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Objective: thumb Ⅱ ° defect, will lose 50% of the functionality of thumb, and 25% of the side of the hand function, serious impact on the function of the hand. With the development of microsurgical techniques, methods of thumb reconstruction increasingly diverse, which is most widely A flap application. Similar with normal thumb skin texture and organizational structure, does not reduce the toe number not affect plantar loading function, especially the aesthetic appearance of the advantage of other repair methods do not have. The articular surface of the distal phalanx of the end of a wide, on both sides of the formation of the enlargement of bone crest bone articular surface, with the thumb near section refers, not physiological match surgery were mostly based on experience to be part of the base of the toe distal bite in addition to, but no reference to bite in addition to a range standard, secondary traumatic arthritis, serious impact on joint activities and the function of the thumb reconstruction. In view of this, this project will be constructed with the distal phalanx of A flap repair thumb Ⅱ ° defect model, different range of resection of the distal phalanx of the articular surface with the thumb near section refers to the biomechanical changes in the bone between the articular surface, and with the normal thumb interphalangeal joint comparative biomechanical indicators for the the clinical thumb Ⅱ ° defects thumb recycling, provide a theoretical basis and the best surgical program. Method: selection of 20 recent the anticorrosive adult cadavers, a total of 40 cases, respectively, from the metacarpophalangeal joint, the the ipsilateral toe distal joint disarticulation retain the ends of both sides of the joint capsule. Since thumb cut ulnar joint capsule, placed in the pressure-sensitive tablets, CSS-44020 series of biomechanical testing machine to 5N / s speed, gradually loaded to 100N, to maintain half a minute, were measured interphalangeal joint flexion 0 °, 45 °, 90 ° articular surface force. 40 specimens were randomly divided into five groups, each eight cases numbered as A, B, C, D, E group in addition to the the toe far phalanx bottom articular surface 1/10, 1/9, 1/8, respectively biting 1/7, 1/6, the transplant repair Ⅱ ° defect of thumb, the same method of measuring recycling thumb, by the force of the articular surface (toe), and then the data were statistically analyzed. 40 volunteers, a total of 80 cases, the Dutch company Philips color ultrasound diagnostic apparatus Philips IE33 probe frequency of 1.7-3.4MHz, the natural extension of the thumb or toe, the probe is located in the distal phalanx or distal phalanx base, perpendicular to the direction of the sound beam means (toe) bone longitudinal axis of the probe coated with a coupling agent, lining the water bag, ultrasound display means (toe) bone near the probe surface, direct measurement of electronic instruments on the ruler means (toe) bone transverse diameter. Results: recycling thumb interphalangeal joint contact area changes: analysis of pressure-sensitive tablets found, compared with normal thumb test group after transplantation bite before and bite except the articular surface of the phalanx of the end of 1/10, 1/9 , 1/8, 1/7, the total contact area is no significant change, each partition the average contact area of ??the re-allocation, the condyle area, the the intercondylar contact area is reduced, other region increased contact area, shows a statistically significant difference (p lt; 0.05); bite in addition to the articular surface of the phalanx bottom 1/6 of the total contact area and the district contact area were significantly reduced after showing a statistically significant difference (p lt; 0.05 or p lt; 0.01). Recycling thumb interphalangeal joint stress and peak stress changes: stress measurement, we found that, compared with the normal thumb test group after the transplant did not bite before and bite except the articular surface of the phalanx bottom 1/10, 1/9, 1 / 8,1 / 7, the the district average stress and peak stress were not changed significantly; bite in addition to the end phalanx articular surface 1/6, the district average and peak stresses increased significantly, showing a statistically significant difference (p lt; 0.05). Conclusion: 1 with the distal phalanges nails flap repair thumb Ⅱ ° defect broad articular surface of the distal phalanx formed on both sides of the enlargement of bone crest seriously affect the appearance of the reconstructed thumb, should be part of the bite the exception. 2 on both sides of the distal phalanx of each bite change significantly after addition of 1/6, the contact characteristics of the recycled interphalangeal joint, the partitions reduce the contact area of ??the total contact area and the average stress, and a significant increase in peak stress, traumatic arthritis easily induced.
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