Dynamic Hip Screw Plating

DHS Plating a short review for PG students

1. Dr. Irfan Khan MBBS,M.S. Fellow in joint replacement & sports medicine SANCHETI HOSPITAL DYNAMIC HIP SCREW

2. THEORY:- Asked frequently as a Short Note. PRACTICAL:- Instrument viva= Identify and elaborate uses of DHS?? Steps of DHS Plating?? Exam point of view?

3. Dynamic H ip Screw (DHS ) It’s a type of implant designed for fixation of certain hip fractures which allows controlled dynamic sliding of the femoral head component along the construct . A n a ssembly consisting of a lag screw, DHS plate and distal cortical screws. Commonly used in Adults. Pediatric sizes are also available. Definition

4. Tensile forces compressive force. Patient happens to bear weight. Screw slides within the barrel to achieve compression at fracture site. Thus idea behind the dynamic compression is union is achieved by micro-motion at fracture site. The DHS plate via its barrel provides strong support to the sliding screw and allows it to collapse in a controlled manner . Principle

5. principle Dynamic & controlled action reduces:- Incidence of screw cut out. Penetration into hip joint.

6. Stable Intertrochanteric femur fractures Basicervical  fracture of femoral neck Sub trochanteric fractures Indications

7. Stable IT femur fractures NO Posteromedial commination. Lateral wall is intact.

8. Richard screw( Lag Screw):- Threaded part:- Dia-12.5mm length-22mm Shaft part:- Dia-8mm length-variable Sizes available:- 50mm to 120mm with interval of 5mm Components of the assembly

9. DHS Plate:- Plate Barrel angles:- 120°–150° to match neck shaft angle. Various sizes varying from 3 holes to 16 holes. Plate is 5.8 mm thick and 19mm wide. Holes are spaced at 16mm distance. Short Barrel length is 25mm. Long Barrel length is 38mm. Components of the assembly

10. Position:- Supine over fracture table Contralateral uninjured leg over leg holder. How to do DHS Plating?

11. Reduction:- Traction Internal rotation May require abduction for hinged fragment disimpaction .

12. Approach :- Palpate GT and axis of femoral shaft Incision starting from GT extending along with the lateral border of femur centrally measuring 7-15cm. Split TFL and distally IT Band if required. Reflect Vastus Lateralis anteriorly.

13. Guide wire insertion:- Either fixed or variable angle guide block is used to place the 2.5mm threaded guide wire. Confirmed under C-arm in both AP & Lateral.

14. Components 2.Triple Reamer

15. After Triple reaming:- Check for the reamer depth reading. To calculate the lag screw length from the direct reading subtract 10mm. Select the appropriate lag screw. Make the lag screw insertion assembly.

16. Insertion of the lag screw followed by plate:- Slide the lag screw assembly over the guide wire. Seat along the centering sleeve over the hole to centeralise and stabilise the assembly. Insert the lag screw by turning the handle clockwise until zero mark on the assembly aligns with the lateral cortex. The threaded tip of the screw lies 10mm from the articular surface. Short barrel if screw size <80mm. Place the DHS plate and distal cortical screws. Release traction. Place the top nut.

17. What are the fallacies?

18. IMPLANT FAILURE:- Screw cut-out. Screw/Plate breakage . Avascular necrosis. Fracture Non-union. Progression of coxarthrosis . Pseudoarthrosis . Infection. Post Operative Complications

19. What is the length of guide wire used? When to use a de-rotation screw? How to look for ideal size of lag screw on x-ray? questions?

20. THANK YOU