Objective To investigate effect of the biological prosthesis on load properties of the proximal femur after hemiarthroplasty with partial resection of the femoral head in order to assess stability of the prosthetic implant.Methods Twenty-four young fresh normal femur (with preservation of femoral head) specimens were assigned to prosthesis group (n =8),control group (n =8) and fatigue group (n =8).Specimens in prosthesis group underwent artificial femoral head replacement using self-designed prostheses.Stress at the femoral head with the model standing on one leg was performed.Biomechanical machine was used to detect the difference of load-stress and load-displacement before and after femoral head replacement under the load of 2000 N.Detection points included lateral superior base of femoral neck (A),medial side of lesser trochanter of femur (B),and inferior side of greater trochanter of femur (C).Results At the load of 2 000 N,the load-stress at inferior side of greater trochanter of femur and medial side of lesser trochanter of femur revealed no significance differences between the normal femur and femur with artificial femoral head replacement (P ＞ 0.05),while the difference was significant at lateral superior base of femoral neck (P ＜ 0.05).There were no significant differences of load-stress at A,B,and C points among fatigue group,prosthesis group and control group (P ＞ 0.05).Conclusion After partial femoral head replacement,the biological prosthesis is effective in maintenance of the normal stress transfer in the proximal femur.

Objective To investigate the method and effect of monosegment pedicle instrumentafinn on thoraeolumbar vertebral fracture.Methods Sixteen patients with thoracolumbar vertebral fractures treated by open reduction and monosegment pedicle instrumentation through posterior approach.Posterolateral bone grafting was done in all cases,9 cases were quite decompressed using laminectomy.The follow-up time Was 8-24 months.The spine radiographs and CT scan were taken pre-and post-operation.The parameters used for clinical evaluation were the Denis pain scale,neurological evaluation by the Frankel scale and bone graft healing evaluation by the Suk scale.Results All of the fractures were reduced satisfactorily during the follow-up.The height of the injured vertebral improved rate was 30.8%,kyphosis of the injured vertebral segment rectified obviously.There was no implant break,and no signs of losing were observed in any patient.Nine patients which had neurological deficiency had average improvement more than one degree by the Frankel scale.After operation the pain score was P1 in 14 patients and P2 in 2 patients.Condnsion For the appropriate patients with thoracolumbar vertebral fractures,open reduction and internal fixation of monosegment pedicle instrumentation through posterior approach is a safe and effective method.

Objective To evaluate the results and relating factors in the treatment of proximal humeral fractures by replacement of humeral head prosthesis. Methods From March 2000 to March 2003, 21 cases with proximal humeral fractures, which were 10 males and 11 females aging from 62 to 82 years with an average of 72.3 years, were admitted to our hospital. All the patients were underwent one-stage operation of humeral head hemiarthroplasty through the anteromedial approach of shoulder joint. The average operative time was 60 minutes (range, 40 to 80 minutes) with a blood loss ranging form 200 ml to 300 ml. According to Neer classification, 6 cases were three-part fractures, 13 four-part fractures, and 2 head-splitting fractures. There were 18 fresh fractures and 3 old fractures. All the fractures were treated with replacement of humeral head prosthesis. After operation, the upper extremity was immobilized for 6 weeks, however, physical therapy, including pendulum, isometric elbow, and wrist and hand exercises, was begun on the first day after surgery. Results The follow-up ranged from 6 to 36 months with a mean period of 14.6 months. No lessening prosthesis, prosthesis dislocation, postoperative infection, nerve damage or periprosthesis fractures occurred. According to the scoring system modification for hemiarthroplasty (SSMH) of UCLA (Los. Angeles, California, USA) based on shoulder pain, functional status, muscle strength and range of motion, the average score was 24.5. Furthermore, the score was above 27 (excellent) in 3 cases, and 24 to 27 (good) in 14, and the excellent rate was 86%. The average score of pain was 9.3, function 8.6, muscle strength 8.2 in 21 cases. Conclusion Replacement of humeral head prosthesis is a preferable method for the treatment of proximal humeral fractures in the elderly patients, with significant effects in keeping the function and relieving the pain of the shoulder joint postoperatively.

Objective To investigate the feasibility and effects of modified Stoppa approach in treatment of anterior pelvic ring fractures.Methods The therapeutic effects of 21 patients with anterior pelvic ring fractures treated through the modified Stoppa approach from June 2008 to August 2011 were summarized and analyzed.According to Tile classification,there were seven patients with type A2 fractures,six with type B2 fractures,five type B3 fractures and three type C2 fractures.Surgical treatment through the modified Stoppa approach included anterior pelvic ring plates for 14 patients,anterior pelvic ring plates and external fixators for four and anterior pelvic ring plates and sacroiliac joint compressed cannulated screws for three.The fracture reduction and post-operative function were assessed by Matta criteria and Majeed system respectively.Results The incision length of the modified Stoppa approach ranged from 10 to 12 cm ( average,11 cm).The operation time ranged from 70 to 120 minutes ( average,95 minutes).The intra-operative blood loss ranged from 400 to 1 000 ml (average,700 ml ).According to the Matta criteria,all 21 patients obtained sound reduction,of whom 15 patients had bony union after 8-20 months follow-up post-operatively.The Majeed score in all patients showed a gradual increase postoperatively.Conclusions The modified Stoppa approach is characterized by convenience and directness in making incisions,clear operation field,easy reduction,few complications and fast recovery and hence is an ideal choice in surgical treatment of anterior pelvic ring fractures.

Objective To compare the biomechanical difference of two internal fixation approaches for the posterior pelvic ring fracture dislocation.Methods Six fresh adult cadaver pelvic specimens were tested biomechanically.Then,the specimens were subjected to Denis-I sacral pelvic fracture.The specimen was first fixed with improved Galveston fixation and then with improved Galveston fixation plus sacral rod.Biomechanical tests were performed from vertical and reversed directions on the fixed pelvis.Results Under vertical compression,the biomeehanical value of the improved Galveston fixation plus sacral rod was lower than that of the improved Galveston fixation,with no statistical difference between two methods(P ＞ 0.05).Under the reversed compression,the biomeehanieal value of the improved Galveston fixation plus sacral rod was lower than that of the improved Galveston fixation,with statistical difference between two groups(P ＜ 0.05).Conclusion The improved Galveston fixation combined with sacral rod can increase the anti-reverse stability of the posterior pelvic ring.

Objective To explore the anatomic basis for and clinical outcomes of the internal fixation which preserves the pronator quadratus (PQ) for distal radius fractures.Methods Twenty cadaveric specimens of adult upper extremity were used for this study (14 males and 6 females).The radial and ulnar lengths of PQ,the distal and proximal widths of PQ,the distances from the distal end of PQ to the articular surface of the distal radius and to the transverse line of the wrist,and the width of the bony tunnel of PQ were dissected and measured to study the anatomical features of PQ.A retrospective study was conducted of the 18 distal radius fractures which had been treated from March 2015 to March 2017 by internal fixation with T-shaped anatomic locking compression plate (LCP) with PQ preserved.They were 8 males and 10 females,with an average age of 52.7 years (range,from 28 to 65 years).According to the AO classification,there were 8 cases of type 23-A,5 ones of type 23-B and 5 ones of type 23-C1.The functional outcomes of the wrist were assessed using the Cooney scoring system at the last follow-ups.Results The PQ muscle was flat and like a right angle trapezoid with rich blood vessels.The radial and ulnar lengths of PQ were about 4.60 cm and 4.46 cm;the distal and proximal widths of PQ were about 4.41 cm and 4.48 cm;the distance from the distal end of PQ to the transverse line of the wrist was about 3.61 cm;the widths of the distal and proximal bony tunnels were about 3.08 cm and 1.91 cm.The 18 patients were followed up for 6 to 36 months (average,11.5 months).Bone union was achieved in all the patients after a mean time of 2.5 months (range,from 2 to 3 months).The mean Cooney score for the wrist function was 97.7 (range,from 95 to 100) at the last follow-up,yielding an excellent rate of 100％.Conclusions The transverse line of the distal radius fracture is located between 1/4 and 1/2 of the distal PQ.The bony tunnel of PQ is wide enough.It is feasible to preserve the distal PQ muscle in the internal fixation of distal radius fractures of types 23-A,23-B and 23-C1,because it may lead to rapid recovery of the patients and satisfactory wrist function.