ABSTRACT
Objective To compare the effectiveness and mechanical differences in the dynamic hip screw (DHS), proximal femoral nail antirotation (PFNA), and proximal femoral internal fixator (PFI) for fixing complex unstable proximal intertrochanteric fractures by biomechanical testing. Methods Eighteen Synbones of the proximal femur were made to simulate complex unstable femoral intertrochanteric fracture models (Evans-Jensen TypeⅢ), which were fixed by DHS, PFNA, and PFI, respectively. The models were tested using a biomechanical testing machine, in order to compare their differences and advantages for fixing fractures. Results Under the compressive loads of 300, 600, and 1 200 N, the fracture displacement of the DHS was the maximum, with a significant difference compared with PFNA and PFI (P0.05). Under torsional loads of 300, 600, and 1 200 N, the torsional displacements of DHS and PFNA at the fracture ends were the maximum, with no significant difference (P>0.05). There were significant differences between PFI and PFNA as well as PFI and DHS (P<0.05). Conclusions For complex unstable proximal intertrochanteric fractures, the stability of the compression resistance of the PFI system is similar to that of the PFNA system. However, the torsional resistance of PFI is stronger than that of PFNA. The DHS system shows the least resistance with respect to compression and torsion.
ABSTRACT
Fractures of the femoral head (FFH) are mainly seen in young adults,and the majority mechanism is due to dashboard injury in crushing vehicles.FFH can be present with or without posterior dislocation of the hip joint.Except for periarticular pain and hip dysfunction,the typical signs include flexion,adduction and internal rotation of the hip and shortening of involved limb.CT and MRI get their popularity as diagnostic methods for FFH.An emergency open reduction should be indicated in the scenario of failed closed reduction in FFH with posterior dislocation,of FFH with femoral neck fractures,of unmatched head and acetabulum following closed reduction and of deteriorating sciatic nerve damage.Pipkin as well as Brumback classification is still the most popularly used methods,which have great significance for establishment of surgical strategy and prediction of prognosis.More and more clinical evidences show conservative care of FFH should only be indicated for non-displaced fractures or displacement less than 2 mm.These cases must meet the following criteria simultaneously,including stable hip joint,concentric head and acetabulum,no free fractured fragments in the joint space and no labrum entrapment.Operative care is naturally the treatment of choice.Surgical approaches for FFH are hot topics in recent years.In previous control studies to compare Kocher-Langenbeck (K-L) and Smith-Peterson (S-P) approach,it is revealed less operative time,less blood loss and better operative field you can get in S-P approach,however,the incidence of ectopic ossification is higher.Ganz approach,which is characterized by osteotomy of great trochanter,hip capsulotomy and surgical dislocation of the hip,is a novel pattern for operative care of FFH.Ganz approach can show the entire femoral head,while can not damage medial femoral circumflex artery (MFCA) and induce iatrogenic osteonecrosis of the femoral head (ONFH).Various screws are the main implants for the fixation of fractured femoral head.Osteoarthritis and ONFH are two principal complications following FFH,which not only closely associate with severity and mechanism of primary injury,but also correlate with reduction quality and iatrogenic factors.Artificial hip joint replacement is a rational choice for extremely comminuted femoral head and these FFH in the elderly.
ABSTRACT
Objective To investigate the mechanical stability and clinical outcome of minimally invasive plate osteosynthesis of pubic ramus fractures.Methods Stability of minimally invasive plate osteosynthesis and traditional open fixation of pubic ramus fractures was compared in finite element analysis.A retrospective analysis was performed on fractures of pubic rami (126 sides) in 101 consecutive patients treated with minimally invasive plate osteosynthesis from 2005 to 2012.Operation time,intraoperative blood loss and follow-up of fracture healing were evaluated.Results In finite element analysis,traditional open fixation and minimally invasive plate osteosynthesis resulted in the maximum pelvic force of 7.35 MPa and 5.59 MPa,maximum fracture displacement of 4.31 mm and 4.38 mm and relative fracture gap displacement of 0.029 mm and 0.012 mm.Displacement of fracture gap after minimally invasive plate osteosynthesis and traditional open fixation was reduced 26％ and 59％ respectively.In the clinical study,the surgery acquired for pubic ramus fractures averaged 65 minutes with mean blood loss of 94 ml.Follow-up duration was 5-50 months (mean,24.3 months).Reduction of the fracture as assessed using Matta' s criteria was excellent in 118 sides (93.7％),good in eight sides (6.3％).Totally,the fracture was healed within postoperative 12 weeks in 117 sides and within postoperative 6 months in 9 sides.No iatrogenic nerve or vascular injury occurred.Conclusions Minimally invasive plate osteosynthesis is a safe and effective technique for fixation of pubic ramus fractures.Moreover,satisfactory results can be achieved together with less trauma and better cosmetic effect.