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Objective:To compare the biomechanical properties of dynamic hip screw (DHS), traditional cannulated compression screw (CCS) configuration, traditional CCS configuration+medial locking plate and compression buttress screw (CBS) in the treatment of femoral neck fracture by finite element analyses.Methods:A simulation model of Pauwels type Ⅲ femoral neck fracture with discontinuous medial cortex was established by the finite element method. The maximum displacement, maximum principal stress, normal form equivalent stress, hip varus angle and fracture end stress were compared between DHS (group A), traditional CCS configuration (group B), traditional CCS configuration+medial locking plate (group C) and CBS (group D) in the simulation model.Results:In the internal fixation model in groups A, B, C and D, respectively, the maximum displacement of the femur was 0.41 mm, 2.04 mm, 0.94 mm and 0.30 mm; the maximum displacement of internal fixation 0.34 mm, 1.18 mm, 0.84 mm and 0.22 mm; the peak normal form stress of internal fixation 83.6 MPa, 231.4 MPa, 259.8 MPa and 194.8 MPa; the maximum principal stress of internal fixation 52.3 MPa, 216.3 MPa, 151.7 MPa and 74.6 MPa; the maximum normal form stress of the femur 101.1 MPa, 282.3 MPa, 100.5 MPa and 181.2 MPa; the maximum principal stress 99.7 MPa, 201.0 MPa, 60.9 MPa and 56.1 MPa; the axis angle of the femoral neck after loading 179.55°, 176.97°, 179.66° and 179.64°; the normal form equivalent stress at the fracture end ranged from 42.0 to 50.0 MPa, from 258.7 to 282.3 MPa, from 50.8 to 58.1 MPa, and from 45.3 to 60.4 MPa.Conclusion:Considering stability, stress distribution and prevention of hip varus and femoral neck shortening, CBS may be a choice treatment for femoral neck fracture because it is comparable to DHS in mechanical stability.
RESUMO
Objective:To compare the complications in young adults with femoral neck fracture after internal fixation with compression buttress screws (CBS) versus 3 parallel partially threaded cannulated screws (PTS).Methods:A prospective study was conducted of the 120 young adults with femoral neck fracture who had been treated from July 2016 to December 2017 at Department of Orthopaedic Surgery, Shanghai Sixth People's Hospital. Of them, 60 were subjected to PTS fixation (control group) and 60 to CBS fixation (observation group) according to their will. In the control group, there were 38 males and 22 females with an age of (46.1±7.6) years, and 17 cases of types Ⅰ-Ⅱ and 43 cases of type Ⅲ by the modified Pauwels classification; in the observation group, there were 42 males and 18 females with an age of (44.8±8.1) years, and 11 cases of types Ⅰ-Ⅱ and 49 cases of type Ⅲ. The 2 groups were compared in postoperative complications. A stratified analysis was performed according to the modified Pauwels classification.Results:Comparability was indicated between the 2 groups because there was no significant difference in their baseline demographic information ( P>0.05). The incidences of fixation failure (8.3%, 5/60), nonunion (5.0%, 3/60), femoral neck shortening<10 mm(10.0%, 6/60) and lateral withdrawal (11.7%, 7/60) in the observation group were significantly lower than those in the control group [38.3% (23/60), 28.3% (17/60), 41.7% (25/60) and 71.7% (43/60), respectively] ( P<0.05). There was no significant difference in the incidence of avascular necrosis of the femoral head or of medial migration between the 2 groups ( P>0.05). The stratified analysis showed that the incidences of fixation failure and nonunion in the observation group were significantly lower than in the control group for fractures of the modified Pauwels type Ⅲ ( P<0.05). The incidences of femoral neck shortening<10 mm and fixation loosening in the control group were significantly higher than in the observation group for fractures of all the modified Pauwels types ( P<0.05). Conclusion:Compared with conventional PTS fixation, CBS fixation can significantly reduce postoperative complications in young adults with femoral neck fracture, especially those with high energy fracture of the modified Pauwels type Ⅲ.
RESUMO
Objective To investigate the advantage of the technique of static compression screws with medial support using one ordinary cannulated compression screw (OCCS) and 2 headless cannulated compression screws (HCCSs) in reducing complications in the treatment of vertical femoral neck fractures.Methods From December 2014 to July 2017,79 patients were treated at Department of Orthopaedics,The Sixth People's Hospital of Shanghai for vertical femoral neck fractures.They were 51 men and 28 women,aged from 20 to 65 years (average,49.1 years).Their injury involved 45 left sides and 34 right sides.Of them,37 were treated with one OCCS at the top and 2 HCCSs at the bottom of a triangle arrangement for fixation of the vertical femoral neck fracture (the experimental group);the other 42 were treated with 3OCCSs at a triangle arrangement for fixation of the vertical femoral neck fracture (the control group).Their fracture healing and complications were followed up at postoperative 6 weeks,3,6 12,18,24 months and any time of discomfort by anteroposterior and lateral X-ray films of the knee joint.Results The 2 groups were compatible due to insignificant differences between their preoperative general data (P ＞ 0.05).This cohort was followed up for 9 to 24 months (average,17.5 months).Of them,52 achieved fracture union.Of the 27 patients who failed,8 were in the experimental group (21.6％) and 19 in the control group (45.2％),showing a significant difference in the rate of failure between the 2 groups (P ＜ 0.05).In the experimental group,the rate of nonunion was 8.1％ (3/37),the rate of implant failure 18.9％ (7/37),and the rate of fermoral neck varus 8.1％ (3/37),all significantly lower than those in the control group [26.2％ (11/42),40.5％ (17/42) and 23.8％ (13/42),respectively] (P ＜0.05).Conclusion For treatment of vertical femoral neck fractures,the technique of static compression screws with medial support is not only easy but also leads to a lower rate of complications.