| Because of the complex and varied types of acetabular fractures,the risk of vascular and nerve injury is higher than other fractures,the surgical treatment has always been one of the greatest challenge for surgeons.An important factor affecting the long-term effect of patients is the reduction quality of acetabular fracture.Principally,some simple and undisplaced acetabular fractures allow conservative treatment,most high-energy injuries result in hip instability and acetabular mismatch should be anatomic reduction and internal fixation combined with joint replacement to allow early range of motion.The sequence and direction of fracture reduction should be planned in detail before surgery.The selection and placement of internal fixators are also required.First,the internal fixation device should be strong and reliable to obtain the initial stability.Second,the length and direction of the screw should avoid contact with the acetabular joint.Third,the surrounding soft tissue should be remove minimally to retain as much bone mass as possible.Among the various types of acetabular fractures,the fractures involving the posterior wall and the posterior column are more common.The reconstruction plates,locking plates,and lag screws are frequently used.All of the above plates should be pre-bent according to the shape of the fracture site,whether through the plate screw hole or the use of lag screw fixation alone,operations in the acetabular danger zone should be avoided.Great skill and experience are required for surgical treatment of acetabular fractures.Due to limited visual field,the anatomical morphology and the reduction are difficult to be performed under direct vision,the anatomical morphology and acetabular characteristics should be recognized as a whole.Each of the plate placed onthe posterior column needs to be pre-bent to match the shape of the posterior acetabular column,the lack of experience will delay the operation.In addition,commonly used reconstruction plate may result in insufficient coverage area and poor stability,although using lag screws or increasing the number of plates can increase stability,the exposure range,the rate of bleeding and nerve injury increases correspondingly.In the view of above,we first used a W-shaped acetabular angle plate that matched the anatomical morphology to fix the acetabular posterior column fractures with biomechanical analysis.Then the reduction degree of the posterior column and the stress distribution around the acetabulum were analyzed,the model of associated posterior column and posterior wall fracture was established and the biomechanical characteristics of W-shaped acetabular angle plate fixation were compared.Finally,the clinical data were analyzed retrospectively to evaluate the efficacy of W-shaped acetabular angle plate in the treatment of posterior acetabular fracture.Part one Biomechanical comparison of the stability of the posterior column acetabular fracture fixed with four kinds of internal fixatorObjective: To compare the stability and feasibility of four fixation constructs in posterior column acetabular fracture.Methods: Twenty embalmed cadaveric pelvis with a posterior column acetabular fracture were allocated to one of four groups: 1)a reconstruction plate,2)a reconstruction plate with a posterior column lag screw,3)double reconstruction plates,and 4)a W-shaped acetabular angular plate.These constructs were mechanically loaded on a testing machine and constructs stiffness were measured.Strain gauges were utilized to measure the mechanical behavior in the condition of compressive force.Results: Final stiffness was not different between the two reconstruction plates(445.81±98.30 N/mm)and W-shaped acetabular angular plate(447.43±98.45 N/mm,P=0.524),both of which were superior to one reconstruction plate(248.90±61.95N/mm)and combined one lag screw(326.41±94.34 N/mm).Following the fixation of W-shaped acetabular angular plate,the strain distribution was similar to the intact condition around the acetabulum.The parameters of W-shaped acetabular angular plate that were observed at the superior region of the acetabulum was less than one reconstruction plate(P<0.05),one reconstruction plate with lag screw(P<0.05),and two reconstruction plates(P<0.05).Conclusions: The novel W-shaped acetabular angular plate fixation was feasible to provide the biomechanically stiffest construct for stabilization of posterior column acetabular fracture,it also resulted in a partial restoration of joint loading parameters toward the intact state.Part two The influence of the reduction of posterior column fracture and the stress distribution around the acetabulumObjective:To compare the reduction of acetabular posterior column fracture on the changes of stress around the acetabulum under different pressuresMethods: Twelve embalmed cadaveric pelvis with a posterior column acetabular fracture were selected 10 sites around the acetabulum and 2 sites up and down the neck of the femur to install resistance strain gauge,when the fracture distance was 1mm,2mm,3mm and 4mm respectively,the W-shaped acetabular angular plate was used for fixation,the stress data of each site at 600 N,1000N and 1400 N were recorded.Results: The stress value at each site changed with the different pressure,and the stress difference at each site between intact acetabulum and different fracture acetabulum was statistically significant.When the pressure was 600 N,there was no statistical difference between the fracture group and the intact group at sites 1,3,4,5,6,8 and 12.When the pressure gradually increased to 1000 N and 1400 N,the difference between the fracture group and the intact group at sites 1,2,5 and 6 in the weight-bearing top region was statistically significant,and increased with the distance of fracture line.Conclusions: The stress-tension system changed after acetabular fracture,the plate fixation can partially restore mechanical properties,depending on the degree of reduction of the fracture,any displacement greater than 1mm at pressures greater than 1000 N would redistribute stress around the acetabulum.Part three Biomechanical consequences of a novel W-shaped acetabular angular plate for posterior column and posterior wall acetabular fractureObjective:To evaluate the biomechanical characteristic of a novel W-shaped acetabular angular plate for posterior column and posterior wall acetabular fracture and to compare it with conventional forms of fixations.Methods:Twelve embalmed cadaveric pelvises were used for this study.After measured the baseline stiffness and strain distribution in the intact state,all pelvises were created a posterior column and posterior wall acetabular fracture and then allocated to one of three groups randomly: a reconstruction plate and a lag screw,double reconstruction plates,and a W-shaped acetabular angular plate.The structure stiffness and strain distribution were recorded at a cyclic compression loading of 1400 N.Results:The double reconstruction plates and the W-shaped acetabular angular plate displayed the highest stiffness than a combined plate and lag screw.The W-shaped acetabular angular plate provided a similar strain distribution in the superior,posterior and interior regions when compared with the intact condition,which were both superior to a single plate with a lag screw.Conclusions:The W-shaped acetabular angular plate acted as a novel internal fixation for posterior column and posterior wall acetabular fractures could provide a rigid stiffness,and resulted in a restoration of joint loading parameters toward the intact state.Part Fuor The clinical study on the treatment of posterior acetabular fracture with the W-shaped acetabular angular plateObjective:To analyze the clinical effect of W-shaped acetabular angular plate in the treatment of posterior acetabular fractureMethods:A retrospective analysis was performed on 38 patients whounderwent acetabular fracture internal fixation using W-shaped acetabular angular plate from January 2015 to January 2017.There were 12 cases of posterior wall fracture,3 cases of posterior column fracture,2 cases of associated posterior column and posterior wall fracture,8 cases of transverse fracture,9 cases of associated transverse and posterior wall fracture and 4 cases of T-type fracture.Blood loss,operation time and reduction quality were statistically analyzed,the fracture healing and the heterotopic ossification were analyzed one year after surgery.Results:The operative time and blood loss of single approach were less than that of combined approach.According to Matta criteria,there were 26 excellent cases(68.4%),9 good cases(23.7%)and 3 poor cases(7.9%),with an excellent and good rate of 92.1%.According to Brooker criteria,there were 29 cases(76.3%)at grade 0,5 cases(13.2%)at grade 1,3 cases(7.9%)at grade 2,and 1 case(2.6%)at grade 3 at the 12-month follow-up.According to Merle d’Aubinge criteria,there were 21 excellent cases,12 good cases,4 common cases and 1 poor case,with an excellent and good rate of 86.8%.Conclusions: The W-shaped acetabular angular plate could be used alone or combined for the fixation of posterior acetabular fractures.It could avoid screws into the joint,reduce the operation time and intraoperative bleeding,allowed early range of motion. |
PDF Full Text Request