Mechanical strength of biological canulated cancellous screw / 医用生物力学

Objective To develop a biological canulated screw and evaluate its mechanical properties, so as to provide theoretical basis for the bio therapy of fracture with enrichment technique of bone marrow stem cells, which could be diffused through the canula, particularly for promoting bone union of femoral neck fracture and preventing avascular necrosis of femoral head. Methods TC4 titanium alloyed canulated cancellous screw (7.3 mm in diameter) commonly used for internal fixation of femoral neck fracture was improved by designing an end sealing plug and side holes in a 900 mm-long canulated screw. The side holes were arranged along the axis of screw, and the first side hole was 20 mm away from the screw tip. The distance between each side hole was 10 mm, and the number of side holes ranged from 0 to 6. The screws without holes were tested as control, and the rest were divided into two groups, i.e., group A: force direction parallel to the side hole, group B: force direction perpendicular to the side hole. Three point bending test on the screw was conducted by using Instron material testing machine, so as to study the relationship between the mechanical strength of the screw and the number of side holes, and the loading direction. Results (1) When the force direction was parallel to the side hole, which was confined within 0, 1 or 2, the bending deformation of the screw reached 3 mm, and no differences were found in the maximum loads and elastic modulus of the screw. However, when the number of side holes was increased to 3 or more, a significant reduction in the maximum load and elastic modulus of the screw was found (P＜0.05). (2) When the force direction was perpendicular to the side hole, which was confined within 0,1 or 2, and the bending deformation of the screw reached 3 mm, no significant differences were found in the maximum loads of the screw. While no significant difference was found in the elastic modulus of the screw when the side hole was 0, 1, 2 and 3. With an increase in the number of side holes, the maximum loads (≧ 3 side holes) and elastic modulus (≧ 4 side holes) were significantly reduced (P＜0.05). (3) When the force direction was perpendicular to the side hole and the number of side holes was 3 or more, the maximum loads and elastic modulus of the screw were all significantly higher than the screw with the same number of side hole under force direction parallel to the side hole. Conclusions (1) For achieving better mechanical properties of the screw, the number of side holes in titanium alloyed canulated cancellous screw (7.3 mm in diameter) should be within 2; (2) If the number of side holes was equal or over 3, screws under force direction perpendicular to the side hole could provide better mechanical properties than screws under force direction parallel to the side hole. This study may provide some theoretical evidence and support for future clinical development and practice of the biological canulated screw.

Treatment of distal clavicle fracture with distal radius volar locking compression plate / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To observe the early clinical outcomes of the internal fixation with distal radius volar locking compression plate (LCP) in treatment of distal clavicle fracture.</p><p><b>METHODS</b>Six patients with unilateral distal clavicle fractures, identified as type II according to Neer classification system, including 4 males and 2 females, were treated with open reduction and internal fixation using a distal radius volar LCP. Bone union was evaluated by routine X-ray radiography, and shoulder joint function were assessed by Constant score system.</p><p><b>RESULTS</b>All fractures achieved bone union at 6 to 8 weeks postoperatively, and Constant scores ranged from 95 to 100 at the postoperative 10 to 12 weeks.</p><p><b>CONCLUSION</b>Fixation of distal clavicle fracture with distal radius volar LCP demonstrates excellent effects of bone union with rarely early complications, thus providing a new technique to treat distal clavicle fracture.</p>

The study of bipolar radiofrequency chondroplasty to cartilage injure of goats / 中华外科杂志

<p><b>OBJECTIVE</b>To study the evaluation of bipolar radiofrequency (RFE) chondroplasty to cartilage injure.</p><p><b>METHODS</b>Sixteen goats underwent resection of anterior cruciate and medial meniscus to create cartilage injured model. Bipolar frequency energy chondroplasty were performed on injured articular cartilage 3 months after operation. The left knee was regarded as sham-operated control. The zero time effects and later changes of radiofrequency on cartilage surface and chondrocytes were observed.</p><p><b>RESULTS</b>At zero time, the rough injured surface became smooth, and clefts were melted. Some chondrocytes were dead in the superficial layer, cells in deeper layer remained alive. Three months later, the surface of the articular was smoother than the sham-operated side. The histological modified Mankin' s score of cartilage was significantly higher than the sham-operated side (operated side 12 +/- 4; sham-operated side 14 +/- 5, P < 0.01). The result of Fluorescence-activated cell sorter (FACs) showed that there were no obvious difference of dead chondrocyte between operated side and sham-operated side, (24 +/- 10)% and (12 +/- 1)% (P > 0.05).</p><p><b>CONCLUSIONS</b>Bipolar radiofrequency energy (1 grade) does not create more chondrocyte death than the sham-operated side. Bipolar radiofrequency chondroplasty is an appropriate method to treat articular cartilage injury.</p>

Total hip arthroplasty for Crowe type-IV development dysplasia of hip in adults / 中华外科杂志

<p><b>OBJECTIVE</b>To determine the operation procedure of total hip arthroplasty (THA) for Crowe type-IV developmental dysplasia of hip and its relationship with nerve injury.</p><p><b>METHODS</b>A consecutive series of 39 THAs was performed for Crowe type-IV developmental dysplasia of hip in 35 patients (all female). The mean age of the patients at the time of surgery was 46 years (range 36 - 56 years). Thirty-five hips in 31 patients were followed up. The average follow-up period of the whole series was 4 years (range 1 - 8 years). All procedures were carried out through a lateral-posterior approach. In 33 of 35 hips, the cup was inserted in the "true" acetabulum. All the prostheses used were cementless, except for 5 cemented femoral stems in 5 patients. Each patient was evaluated clinically and by radiographs before the operation and during the follow-up period, according to the Harris hip score (HHS).</p><p><b>RESULTS</b>None of the cups and stems were revised for aseptic loosening, dislocation or infection during the follow-up period. The mean preoperative HHS was 43 compared with the postoperative HHS of 87. The mean amount of postoperative leg lengthening was 5 cm (range 4 - 6 cm).</p><p><b>CONCLUSIONS</b>The reconstruction of the hip at the level of the "true" acetabulum through a lateral-posterior approach is a safe and effective procedure of THA for Crowe type-IV developmental dysplasia of hip in adults. Acute leg lengthening of less than 6 cm could not cause nerve injury.</p>