1) Proper proximal fixation of the femoral implant is crucial for the success of Austin Moore's prosthesis (AMP) surgery to provide mechanical stability and allow bone grafts to consolidate. 2) Inadequate proximal fixation is one of the primary reasons for painful failure of AMP, which can result in prosthesis subsidence, loosening, and loss of alignment. 3) Achieving good proximal fixation requires careful pre-operative planning, preservation of femoral neck bone stock, impaction grafting of the proximal area, and selection of an appropriately sized implant.

1. Austin Moore’s Prosthesis Technique Vinod Naneria Girish Yeotikar Arjun Wadhwani Choithram Hospital & Research Centre, Indore, India

2. The philosophy Proximal fixation of the implant is crucial in the success of the surgery. A tight fixation gives mechanical stability, and allow the grafts in the fenestration to consolidate, making it a self-locking device. This prevents over-loading of calcar – no subsidence, no loosening, no failure.

3. Painful AMP An AMP fails on the table. Almost always the success of the surgery can be predicted on the table. Be prepared for change to plan “B” or “C”. Be prepared for peri-operative calcar split.

4. Painful AMP- two primary reasons Inadequate Proximal Fixation Loose Prosthesis Calcar absorption Subsidence of the prosthesis Loss of varus alignment in the canal Acetabular cartilage erosion

5. Inadequate Proximal Fixation Not under our control Elderly Osteoporotic Wide canal Under our control Faulty operative technique Over reaming by improper Rasp Improper selection of Implant

6. Proximal Fixation Tips & Tricks Pre-operative assessment of the Canal. Proper neck cut. Avoid comminuting Calcar Femoris. Save at least 1cm of neck at Calcar Insert canal finder from Piriformis Fossa In wider canal, avoid use of rasp.

7. Proximal Fixation Tips & Tricks Select proper Implant which will fill the proximal femur without increasing comminution. Use a artery forcep in the prosthesis proximal hole ( originally for extraction), for rotation control during insertion.

8. Proximal Fixation Tips & Tricks Impaction grafting: The most important area is the medial side near calcar. Graft should be inserted when nearly half of the prosthesis has gone inside. Fill the fenestrations of the prosthesis with bone grafts, as the prosthesis advances in to the canal. The color of the implant should not over-hang on the calcar. If done properly, it should rest on the neck and will compress the grafts.

10. Posterio-lateral incision in lateral decubitous position

12. Quadratus Gemeli Piriformis Sciatic Nerve Gluteus Maximus Cut the rotators close to the bone

13. Incise the capsule in “T” shape

14. Measure the size of the head

15. Superior lateral neck attched to Gr. Troch must be removed

16. Neck Cut

17. Piriformis fossa as entry point

19. Bone grafts harvesting

20. Selection of Implant Pre operative planning Intra-operative planning Correct head diameter Correct stem width Correct length of collar Cement Tension band wiring

21. Variables - Implant Head size Stem size Collar width Offset Neck – shaft angle Stem width Number & size of stem holes

22. Prosthesis design: Proper Offset Stem Diameter Neck over hang Fitness at proximal part

23. Half inserted prosthesis

24. Packing of graft in the medial wall

26. Graft in the distal hole

27. Grafts in the proximal hole

28. Final setting

29. Trochanteric index

30. Reduction by gentle pressure

31. Capsular repair

32. Post Op X-ray

33. Bone growth on medial side and in the fenestrations

34. AMP - summary Pre operative planning key to ensuring success is careful planning It’s all in the mind If you work on the surgery before hands on mind in brief you can have both hand free and brain free surgery

35. AMP - Summary Femoral head size Neck preparation according to AMP Entry point Reaming Pack the bone grafts in fenestrations. Impaction bone grafting

36. AMP - Summary Post operative Regimen antibiotic – 24 hrs Abduction pillow Bed side sitting – 24 – 48 hrs Walking with support – 3 rd – 5 th day Weight bearing as tolerated

37. Failure & Success - Amp? Most AMP fails on the table Subsidence and Loosening depends on proximal fixation achieved on table Once the proximal locking holes filled with bone – the prosthesis is stable & long lasting. Hypertrophy of medial side, lateral wall hypertrophy, & new bone at the tip ensures long term success.