MOBILE BEARING TOTAL KNEE REPLACEMENT

1. MOBILE BEARING TOTAL KNEE REPLACEMENT Naval Hospital of Athens 1st Orthopaedic Department

3. Kinematic conflict • Reproduction of normal knee biomechanics- reduction of contact forces • Surfaces “convex to flat” produce high contact forces but have freedom in torsion & reduced strain to PCL during posterior femoral condyle movement • “Concave to convex” reduced contact forces & reduced torsion

4. Restricts torsion between femorotibial joint allowing torsion between tibial plateau and polyethylene Contact surface increases very much Contact forces decrease respectively Closer to normal posterior movement of femoral condyles, at least during the first degrees of flexion Callaghan et al, JBJS (Am) Mobile bearing polyethylene

6. Μobile bearing • Allow the torques and shear forces of gait to be transferred to soft tissues in a fashion similar to normal knee. • Soft tissue strengthening – remodeling during rehabilitation • Better patellar tracking • Rotation of polyethylene can forgive SMALL errors of orientation Sansone et al ,j arthroplasty 2004

7. Bartel et al, 1985,1991

8. 527 total knee replacements with mobile bearing Period 1987- 2005 48% left knee, 52% right knee 94 male, 433 female Our experience

11. Patelofemoral joint • No patella replacements • Shaving of pathological cartilage resulting in smooth articular surface • Denervation of the periphery of the patella • Removal of osteophytes

14. Subvastus approach

15. Surgical preparation • 1.5gr cefuroxim on admission. Antibiotic regime for 3 days post op • Skin preparation with Betadine scrub, Betadine solution (3 times) starting from the foot • Strict rules in theatres room in all levels

16. Infections • 10 superficial postoperative infections which were treated with antibiotics • No revisions because of infection

17. Patients followed up clinically and radiologically in 6 weeks, 6 months, 1 year and periodically every 2 years 10-20% of the patients were not examined after the two year follow up unless there was a problem Follow up

18. Range of motion

28. Revisions • One LCS and one Genesis II because of aseptic loosening of femoral component • Two revisions because of trauma- supracondylar femoral fracture in one and tibial fracture in the second • One Polyethylene dislocation

31. Conclusions • The results of 18 years experience in mobile bearing TKR, justify our choice • These results are a strong confirmation of the theoritical advantages of mobile bearing in knee kinematics

32. THANK YOU