Uploaded byDr. Anurag Mittal
Dynamic hip screw
This document discusses the dynamic hip screw (DHS), used to treat intertrochanteric hip fractures. The DHS provides controlled collapse and dynamic action to reduce complications like screw cut-out. Key steps of the procedure include closed reduction of the fracture, guide pin and plate insertion at 135 degrees, and measuring screw length. Factors like tip-apex distance and screw position are important to prevent complications. The DHS works by creating compression as the lag screw collapses into the barrel post-operatively.
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Dynamic hip screw
- 1. DYNAMIC HIP SCREW DRANURAG MITTAL ORTHO UCMS
- 2. INDICATION • Stable intertrochantericfracture till 2.1 –study by evans and another by Hornby-non operative vs operative • Low complication ,mortality rate,pain, leg swelling, sores –same in both • But shorter hospitalization • Better restoration of normal anatomy • Ability to live independently • Basicervical neck of femur # with derotation screw • Unstable # with • TSP • Axial dynamic compression plate • IHS
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- 8. Principle • Controlled collapse •Dynamic action reduces incidence of screw cut out and penetration of screw into hip joint
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- 11. Reduction • Undisplaced #-noreduction,slight IR • Displaced#- • extension , • Abduction-corrects varus • IR –”screw home” the distal fragment • Evaluation • #displacement • Neck shaft angle • Anteversion • Femoral shaft ‘sag’ • Rotation checked clinically
- 12. Lateral approach to theproximal femur
- 13. Guide pin insertion •For 135 angled plate • If higher angled plate-entry moved 5 mm distally for 5 degree increase
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- 17. • Why 135ideal?? • Hip joint resultant force-159- difficult insertion/cut out • 130-high bending load • Influence of nail plate angle on bending moment: Larger angle results in smaller moment because of shorter distance (d); conversely, smaller angle results in larger moment because of longer distance
- 18. TIP APEX DISTANCE •Should be <25mm • Tip of screw should lie under 10 mm of subchondral bone • Screw should ideally lie in centre on ap and lateral views • Superior and anterior location avoided-cut out
- 19. Lag screw length •Measuring guide used • Tip extension and immediate telescoping must be taken into account
- 20. Short vs longbarrel • <85 mm—short barrel • >=85 mm—standard barrel • WHY?? • Thread length-22mm • Recommended sliding -25 mm(min 10 mm) • Standard barrel length-38 mm(short-25 mm) • So 22+25+38=85mm
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- 25. Implant insertion andfixation • Long vs short side plate • More dissection • Complicate future surgery • no improvement in proximal purchase • Inherent stability of fracture/reduction not altered • Reduces tensile forces on prox two screws but no additional protection • Same rate of failure
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- 31. • Traction released •Angled plate acts as an aid to reduction • Intraop prox displacement of femoral shaft along the plate before screw insertion • Post op as lag screw collapses into the barrel by impaction • Compression screw-also prevents postop hip screw barrel disengagement
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