ACETABULAR RECONSTRUCTION WITH ALLOGRAFTS, METALLIC ARMATURE AND CEMENTED PROSTHESIS

1. ACETABULAR RECONSTRUCTION WITH ALLOGRAFTS, METALLIC ARMATURE AND CEMENTED PROSTHESIS TECHNIQUE AND LONG TERM OUTCOME M. Kerboull

2. In the early 70’s, 5 years after we started using a metal-metal prosthesis (Mc Kee-Merle d’Aubigné) we had to deal with a high rate of acetabular loosenings At 2 y. 10 % At 10 y. 32 %

3. These loosenings were sometimes associated with severe acetabular bone loss. After some unsuccessful attempts, filling the bone loss with cement or a big socket it seemed to us that

4. bony reconstruction with bone was absolutely necessary.Because a great amount of bone was needed, the use of allografts was indispensable and in 1974 we reactivated our bone bank which existedsince 1955 to fill it with femoral heads resected during THR.

5. COCHIN BONE BANK • 1955: PRESERVATION OF MASSIVE BONES (femur, tibia, humerus) used for bone reconstruction in tumor surgery • 1974: PRESERVATION OF FEMORAL HEADS • 1985: PRESERVATION OF MASSIVE BONES sterilized by gamma radiation ---> Every year 350 femoral heads 80 massive bones

6. 10.74 06.75 Sometimes, it was possible to repair a wide destroyed acetabulum with a big head without any metallic fixation

7. 01.74 12.73 But the existence, not so rare, of a pelvic discontinuity forced us to find a metallic device to secure the fracture

8. We have had since 1970 a hemispheric cross with 4 arms which was used, in the position of a St Andrew’s cross, with the branches bended on the acetabular rim, as an antiprotrusio cage.

9. 1975 1 y PO 1974 PRE-OP In 1974, to secure a pelvic discontinuity, I used this device, one branch bended in a hook inserted under the teardrop, the opposite screwed to the iliac bone, the others cut at an adequate length. This osteosynthesis, associated with autogenous graft to fill the bone defect, led to bone union within a year

10. 2000 26 y PO 1976 2 y PO 1 year later, a prosthesis was implanted leaving the armature in place. At 26 y. PO, despite a fracture of the hook which occurred 3 y PO, a polyethylene wear of more than 7 mm without osteolysis, the cemented fixation of the socket is still strong and the function of the hip satisfactory.

11. In 1976, this hemispheric cross shaped stainless steel armature, with 4 branches, an inferior hook an a superior flange with 4 screw holes was manufactured by Howmedica. It was more rigid and suitable, unique and symmetrical, of medium size. FIRST ARMATURE 1976

12. It allowed a strong, fixation of a pelvic discontinuity and kept in place the grafts coming from a femoral head shaped into cubes and slices to exactly repair the bone defect.

13. 8 m PO PRE-OP This reconstruction seemed strong enough to implant a prosthesis at the same time.

14. 1984 In 1984 this armature became asymmetrical with an anterior branch shorter than the posterior to avoid any contact with the psoas tendon and give the opening plane an anteversion of 15°

15. It also became multiple and there are now a right and a left series of 6 sizes

16. For sockets from 40 to 60 mm in outside diameter

17. First intended to secure a pelvic discontinuity, this device has been systematically used for 35 years every time a bone reconstruction was necessary It acts as a guide and a reinforcement for bone reconstruction

18. ACETABULAR METALLIC ARMATUREHEMISPHERIC CROSS • STIFF enough to ensure a strong fixation of a pelvic discontinuity • OPEN, flexible enough not to change the elasticity of the acetabulum • Automatically provides the artificial hip with the right anatomic centre • Partially unloads the grafts during their incorporation

19. PRINCIPLES OF SURGICAL TECHNIQUE To restore normal anatomic conditions Acetabular cavity of normal size in an anatomic position The choice of the armatureto be implanted is guided by two references : . A healthy controlateral hip, or a radiograph of the homolateral hip before it was destroyed. . If these references are missing, the size of the bony cavity in its inferior part must be taken into account, knowing that after bone reconstruction, the anterior, posterior and medial walls must be at least 7 mm thick.

20. After cleaning the • destroyed acetabulum, • the selected device is • put in place, the hook • under the inferior margin • near the ischium. • Then the device is tilted • at 45°. This movement • should not tend to eject • the hook from the • teardrop. If it does, three possible causes must be explored: • The acetabular device is too large, try a smaller one. • The medial wall just above the teardrop is too thick, thin it down with a rongeur or a gouge until the hook stays in the right position. • The inferior acetabular margin is destroyed by a polyethylene granuloma. It should be repaired with an allograft fragment before inserting the hook.

21. When there is major structural defect of the roof, the superior flange does not come into contact with bone. One must not place the device more vertical neither open it nor bend the flange to adapt it to the bone loss. On the contrary, the acetabular armature should be used as a guide to evaluate the size and location of bone defect as well as the shape and dimension of the allograft fragments needed to achieve bone reconstruction.

22. If there is a defect of the inferior margin, more or less extended to the medial wall, it is first repaired with a bone fragment of the adequate size and shape, wedged in between the edges of the defect to give the hook a solid grasp.

23. Then, the roof bone loss is filled with a bulky graft, if possible unique. This fragment is carefully shaped with the trabeculae properly oriented so that it can resist the pressure stresses in the bearing area. The superior part made convex accurately fits the dome, its inferior part made concave matches the convexity of the device. The flange of the device lies on its lateral part made of subchondral bone.

24. Two screws then fix the flange to the iliac bone, the first, the inferior screw, pass the graft through a reamed hole, directed up and back, to put the armature under tension and bites the sound bone near the sacro iliac joint. A second, usually anterior, is needed to stabilize the armature. Anterior and posterior walls are repaired by embedding slice grafts between the remaining wall bone and branches of the armature. Cavitary defects of pubic bone and ischium, as well as the gaps between structural grafts are filled with impacted cancellous bone.

25. When there is a pelvic discontinuity with a wide gap, it is advisable to close it. This can be done easily using the armature, the hook inserted under the teardrop, a Steinman pin obliquely introduced through a screw hole. A lever movement of the Steinman pin brings the separate bones in contact. The reduction of the fracture is then secured with 2 or 3 screws and bone reconstruction done by wedging slice fragments between bone and branches of the armature.

26. When the reconstruction is achieved, a socket of adequate size is cemented into this restored and armed bony cavity.

27. On a AP x-rays of the hip, the armature appears in a strict lateral view • Obturator hook in close contact with the teardrop • Screws directed up and back, bite the sound bone near the sacro iliac joint

28. You can find details of this technique in Surgical Techniques in Orthopaedics and Traumatology. This technique, we have been using for 35 years, have allowed us to cope with all the cases encountered on over 2000 in the Orthopaedic Department of Hospital Cochin Paris, and for myself on 700 cases.

29. SOME EXAMPLES

30. 1 m PO PRE-OP Bony restoration has been done with a unique bulky fragment. In this case a major bone loss of the roof and a pelvic discontinuity.

31. PRE-OP Here, a Beechtol prosthesis in a big protrusion. X-rays at 9 y. PO

32. PRE-OP The same patient, the controlateral side, severe bone defect But a simpler restoration. The result a 8 y. PO

33. PRE-OP X-rays, 3 y. PO Third consecutive failure, with severe acetabular bone loss

34. PRE OP PO 4 m Here a cementless prosthesis in a high position Restoration of a wide superior defect and implantation of the socket in an anatomic position.

35. PRE-OP Restoration of the inner wall with a wide and thick slice of femoral head. X-rays at 1 y. PO A big bone loss with a complete destruction of the roof, the inner wall and inferior acetabular margin

36. GRAFT CONSOLIDATION

37. 6 m PO 1 m PO Union of the grafts, together and with the host bone, has been obtained within 1 year, as it is shown in this case where demarcation between graft and host bone has disappeared 6 months after the operation.

38. PRE-OP 1 m PO In this other case, where 3 fragments were used.

39. 4 y PO 1 y PO And perfect at 4 y. PO Consolidation is obvious at 1 y. PO

40. PRE-OP 1 m PO Here, two big superposed fragments were used to fill a wide superior defect.

41. 18 m PO 3 y PO And 3 y. PO X-rays at 18 months PO

42. GRAFT REMODELLING

43. 1 m PO 2 y PO Bone remodelling, which began at 2 years, proceded for 5 to 6 years in the bearing zone

44. 4 y PO 7 y PO And 7 y. PO As shown by this X-rays 4 y. PO

45. 1 m PO As well as in the inner wall where at 2 y. PO remodelling is obvious 2 y PO PRE-OP These radiological pictures strongly suggest that grafts are biologically and mechanically incorporated.

46. RADIOLOGICAL PICTURES LONG TERM At long term, there has been, up to now, no serious problem

47. 8 y PO A case at 8 years with a beautiful bone remodelling PRE-OP

48. 1 y PO PRE-OP Another, with the steps of bone remodelling.

49. At 6 y. PO And 10 y. PO

50. PRE-OP 19 y PO Its result a 19 y. PO A pelvic discontinuity