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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 393 - 393
1 Sep 2012
Zlowodzki M Wijdicks C Armitage B Cole P
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Introduction

Femoral neck fractures are a large clinical and economical problem. One of the most common fixation options for femoral neck fractures are multiple cancellous screws. A previous clinical study has shown the lack of washers to be the single largest predictor of fixation failure in the treatment of femoral neck fractures with cancellous screws. This finding was somewhat surprising as washers do not prevent the screws from backing out and do not provide any increase resistance to varus collapse. Therefore a follow-up biomechanical study was designed to test this observation. The purpose was to evaluate the maximal insertional torque of screws in osteoporotic bone with and without washers. We hypothesized that the lateral cortex of an osteoporotic proximal femur does not provide sufficient counter resistance for the screw heads to obtain maximum torque upon screw insertion in the femoral head and that the use of washers would increase screw purchase by providing a larger rigid surface area and subsequent higher counter resistance thereby allowing a higher maximal screw insertion torque.

Methods

We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Two screws each were inserted in each femur either with or without a washer and maximal insertional torque was measured using a 50 Nm torque transducer. The testing was performed using a customized device which allowed the torque transducer to apply a constant axial force and torque speed to the screws. A paired Student's t-test was used to compare the maximal screw insertional torque of screws with washers versus screws without washers in matched pairs.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 512 - 512
1 Sep 2012
Zlowodzki M Armitage B Wijdicks C Kregor P Bruce L Cole P
Full Access

Introduction

The most common treatment options for fixation of osteoporotic distal femur fractures are retrograde nails and locking plates. There are proponents of more elastic titanium plates as well as more rigid steel plates; No clear superiority of one over the other has been established. We aimed to evaluate the mechanical differences between stainless steel and titanium locking plates in the fixation of distal femur fractures in osteoporotic bone. We hypothesized that due to its higher elasticity titanium locking plates can absorb more energy and are therefore less likely to “cut” into the bone compared to stainless steel locking plates resulting in improved metaphyseal osteoporotic fracture fixation.

Methods

We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Within each pair we randomized one femur to be fitted with a Less Invasive Stabilization System (LISS-Titanium locking plate) and one with a Distal Locking Condylar Plate (DLCP-Stainless steel locking plate).

A fracture model simulating an AO 33-A3 fracture was created (extraarticular comminuted fracture) and specimens were subsequently subjected to step-wise cyclic axial loading to failure. We used an advanced three dimensional tracking system (Polhemus Fastrak) to monitor the movement of the distal fragment relative to the real time distal plate position allowing us to evaluate distal implant cut-out.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 224 - 224
1 Jul 2008
Yoon WW Askin G Cole P Natali C
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Introduction: This study highlights the occurrence of significant post operative scoliosis associated with en-bloc resection of pancoast or superior sulcus tumours. We observed the rapid onset of high thoracic scoliosis following en-bloc resections. The Magnitude of the scoliosis, and predisposing surgical factors were reviewed in each of the cases implicating the role of the transverse process or its associated structures in the stabilization of the spine.

Methods: Sixteen patients undergoing en-bloc resection for pancoast tumour were retrospectively reviewed. This was a single surgeon series where all patients had tumour resection over a 3 year period. The number of upper ribs and transverse processes resected were analysed and compared with the magnitude of scoliosis that developed over a follow up period of 2 years.

Results: Four patients had significant resection of the transverse processes of T1 to T3. All of these patients developed scoliosis of rapid onset, convex to the side of the resection. Of the remaining 12 patients either no scoliosis developed, (6 of 12), or scoliosis of less than 12 degrees.

Discussion: We observed rapid development of thoracogenic scoliosis in patients following lung tumour and chest wall resection. Our study shows that excision of the transverse processes is associated with subsequent development of an upper thoracic scoliosis. Preservation of the transverse process appears to be protective. Large resections can be performed with no subsequent scoliosis provided the transverse processes remain intact.

This suggests that the transverse process or its associated structures have an important stabilizing function on the spine.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 349 - 349
1 Mar 2004
Zlowodzki M Vogt D Cole P Kregor P
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Aims: Published series of traditional plate þxation of the femur note rates of up to 69% primary bone grafting, 13% infection, 15% nonunion, 68% late complications, and 25% secondary surgical procedures. A shift from traditional plating to submuscular plating has thus ensued. This series entails an all-inclusive review of the plate þxation experience by two orthopaedic trauma surgeons in a þve-year period at a university trauma center. Methods: Between June 1996 and May 2001, 40 acute diaphyseal femoral fractures in 37 patients were managed utilizing dynamic compression plating via traditional Ç biological È plating with a formal lateral incision (n = 19), or submuscular plate þxation utilizing only a proximal and distal incision (n = 21). A comparison of reduction quality, union rates, and infection rates between traditional plate þxation and submuscular þxation was performed. Results: Thirty-nine of forty femoral shaft fractures healed without need of a secondary procedure. One nonunion occurred in the ORIF group. There was one infection in each group. Two patients treated by submuscular þxation developed signiþcant heterotopic ossiþcation around the femoral shaft which signiþcantly impaired knee motion. There were 6 cases of malreduction in the submuscular group, and none in the ORIF Group. Conclusions: Although the theoretical advantages of submuscular plating are well established, its utilization in the femoral shaft did not have a clear clinical advantage. In addition, its use appears to be more technically challenging, and is associated with a high rate of sub-optimal reductions.