Objective To evaluate the effects of femoral offset (FO) on the stress level of bone cement total hip arthroplasty (THA) in the elder patients by the three-dimensional finite element analysis. Methods The normal bilateral hip joints in two cases was determined with CT imaging,with parameters including FO,neck shaft angle and neck length.The three-dimensional finite element model of THA was built so as to make Von Mises stress analysis of the changes of different neck lengths,neck shaft angles and FO. Results Stress levels in the prosthesis and bone cement reduced monotonically with the increase of neck shaft angles.In the meantime,the stress levels were lowered when neck length was in a range of 35-44 mm,but beyond the range they showed monotonous increase. Conclusions The reduction of stress levels of prosthesis and bone cement,promotion of femur stress and extension of range of motion of hip joints are closely related to FO.FO reconstruction benefits the restoration of abductor force arm and biomechanical function of normal hip joints.

Objective To discuss the surgical indications,relative merits and clinical outcomes of anterior reconstruction plate fixation for treating unstable posterior pelvic ring injuries.MethodsA retrospective study was done on clinical data of 36 patients with unstable posterior pelvic ring injuries treated with anterior reconstruction plate fixation from August 2004 to July 2010 and followed up for minimum one year.There were 25 males and 11 females,at mean age of 35.8 years ( range,13-62 years).There were two patients with anterior dislocation of the sacroiliac joint and 34 with posterior dislocation.According to Tile classification,there were four patients with type B fractures ( B1:3,B2:1 ) and 32 with type C fractures (C1-1:17,C1-2:12,C2:2,C3:1 ).Results All patients were followed up for average 2.3 years ( range,1-6 years).Fat liquefaction and superficial infection were founded in two patients who were cured by dressing change and frequent but low-dose blood transfusion.Eight patients were subjected to iatrogenic lateral femoral cutaneous nerve injury.Meanwhile,five of them was recovered after treatment with neurotrophic drugs,but there were still three patients leaving lateral thigh numbness.One patient had L5 nerve root injury due to pull force,and was recovered after three months of neurotrophic drug therapy.According to Matta and Tometta criteria,the reduction results were excellent in 23 patients,good in 11 and fair in four,with excellence rate of 94％.No reduction loss or implant failure occurred.According to Majeed scoring system,the clinical outcomes were excellent in 17 patients,good in 14,fair in four and poor in one,with excellence rate of 86％.Of the seven patients pre-operatively associated with sacral plexusinjury,three obtained full recovery,two got partial recovery and two were free from recovery.Conclusion The anterior reconstruction plate fixation takes advantages of wide surgical indications,simple exposure,low infection rate,satisfactory reduction and solid fixation and may be a main treatment method for unstable posterior pelvic ring injuries.

Objective To explore clinical and radiological outcomes of treating displaced fractures of proximal clavicle by open reduction and internal fixation with an inverted anatomic locking plate for distal clavicle.Methods From August 2013 to August 2015,12 patients with displaced fracture of proximal clavicle were treated in our hospital by open reduction and internal fixation with an inverted anatomic locking plate for distal clavicle.They were 11 men and one woman,with an average age of 43.5 years (range,25 to 62 years).There were 9 fresh and 2 old fractures.According to the Edinburgh classification,10 fractures were classified as type 1B1 and 2 as type 1B2.After fixation,the 180° inverted plate on the ipsilateral side was placed on the superior aspect of proximal clavicle.The medial fragment was fixed with 2 to 4 pieces of 2.7 mm multidirectional locking screw and the lateral fragment with 2 to 3 pieces of 3.5 mm locking screw.X-ray and CT were performed to assess union,delayed union,nonunion,and hardware failure.Functional outcomes were assessed by Constant-Murley scores and Disabilities of the Arm,Shoulder and Hand (DASH) scores at final follow-ups.Results There were no significant neurovascular injuries intraoperatively.All patients were followed up for an average of 15.6 months (range,12 to 24 months).All fractures healed after an average of 14.3 weeks (range,8 to 24 weeks).At final follow-ups,the mean Constant-Murley score was 96.0 points (range,84 to 100 points) and the mean DASH score 1.9 points (range,0 to 14.8 points).There were no such significant complications as infection,reduction loss or implant failure.Conclusion Displaced fractures of proximal clavicle may be treated with an inverted anatomic locking plate for distal clavicle on the ipsilateral side because of rigid fixation,fine stability and good chance for early rehabilitation.