How to do Dynamic Hip Screw

Dr. Khadijah Nordin

Content

• Introduction• Indication • Plate • Position • Reduction • Approach • Surgical technique• Post op management

Introduction

• DHS – Design to provide strong and stable internal fixation of

variety of intertrochanteric, subtrochanteric and basilar neck fracture with minimal soft tissue irritation.

– Strong: made from stainless steel and are cold worked for strength

– Stable: in view of the number of the screw, dynamic compression plate allow angulation of the cortical screw or axial compression and multiple screw fixation

Indication

• Indicating for fracture of the proximal femur:– Intertrochanteric fracture– Subtrochanteric fracture– Basilar neck fracture

• Indicated for the stable fracture and unstable fracture in which a stable medial buttress can be reconstructed.

Plate

• Plate selection base on: – Barrel length: Standard 38mm length– Barrel angle: commonly 135 barrel angle• The angle that subtended between the femoral neck

and shaft axis

Positioning

• The patient is positioned supine with traction table.

• The ipsilateral arm is elevated in a sling while the contralateral uninjured leg is placed on a leg holder.

• This position is well suited for excellent true AP and cross-table lateral x-rays.

Image intensification

• An image intensifier is required for reduction on the traction table.

• With the patient and fluoroscope properly positioned, obtain AP and lateral images.

Closed reduction

• Reduction is usually achieved by first pulling in the direction of the long axis of the leg in order to distract the fragments and regain length.

• Next comes internal rotation.• The reduction must be checked in both the AP

and lateral with an image intensifier. In case the closed reduction should fail, open reduction will be necessary.

Lateral approach for closed reduction and fixation

• Incise the skin– For insertion of multiple screws, the incision is

centred over the femoral neck axis line, and slightly posterior to the palpable mid line of the trochanter.

– If the soft tissues are thick, the incision may need to be more distal or longer.

Surgical technique• Reduced the fracture

– Determine the anterversion by placing the 2.5mm threaded guide wire anteriorly along the femoral neck, using the appropriate DHS guide.

– Gently hammer the wire into the femoral head

– This anterversion wire will later allow correct placement of the central guide wire in the center of the femoral head

• Insert guide wire– Align the appropriate DHS angle

guide along the axis of the femoral shaft and place it into the femur.

– Point the guide tube toward the center of the femoral head

– Predrilling of the lateral cortex with 2.0mm drill bit is recommended in dense bone

– Insert the 2.5mm threaded guide wire through the appropriate DHS angle guide, parallel to the anteversion wire and directed toward the center of femoral neck.

• Confirm placement– Confirm placement of

the 2.5mm threaded guide wire under the II

– It must lies along the axis of the femoral neck in both AP and lateral view and parallel to the anterversion wire

• Determine insertion of the length– Slide the direct

measuring device over the guide wire to determine wire insertion depth.

– Calibration on the measuring device provide a direct reading

• Calculate reaming depth and lag screw length– To calculate reaming depth, tapping depth and lag

screw length, subtract 10mm from the reading

Direct reading 105mm

Reamer setting 95

Tapping depthLag screw length

95mm95mm

• Reaming to predetermined depth– Assemble the appropriate DHS

triple reamer– Set the reamer to the correct

depth– Insert the DHS triple reamer to

the drive using large quick coupling attachment

– Slide the reamer over the guide wire to simultaneously drill the lag screw, ream for the plate barrel, and countersink for the barrel junction to the present of the depth

• Insert lag screw– Select the DHS lag screw and assemble

the lag screw insertion.– Slide the assembly over the guide wire

and into the reamed hole.– Seat along the centering sleeve over in

the hole to center and stabilize the assembly.

– Insert the lag screw by turning the handle clockwise, until zero mark on the assembly align with the lateral cortex.

– The threaded tip of the lag screw lies 10mm from the joint surface.

– The lag screw inserted 5m in porotic bone to increased holding power and additional controlled collapse

• Align handle– Before removing the

assembly, align the handle so it is in the same plane as the femoral shaft( parallel to the femoral shaft axis when viewed laterally)

– This will allow the proper placement of the DHS plate onto the lag screw

• Removed wrench– Removed DHS wrench and long centering sleeve.– Slide the appropriate DHS plate onto the guide

shaft lag screw until it contact the lateral cortex– Loosen and removed the coupling screw and guide

shaft– Then withdraw the 2.5mm guide wire

• Seat plate– Gently seat the plate

with the DHS impactor.

• Fix plate to femur– Fix the DHS to the

femur with 4.5mm cortex screws

• Insert the compression screw– The DHS compression screw may be used in

unstable fracture to prevent disengagement of the lag screw from the barrel in NWB patient

Postoperative treatment

• Follow up– The first postoperative visit is at 6 weeks. – Check the position of the fracture with

appropriate x-rays. – See the patient at six-week intervals until union of

the fracture and then as desired.

Thank you