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

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

Mobile bearing polyethylene 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)

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

Bartel et al, 1985,1991

Our experience 527 total knee replacements with mobile bearing Period % left knee, 52% right knee 94 male, 433 female

ΔΙΑΓΝΩΣΗn%ΗΛΙΚΙΑ ΟΣΤΕΟΑΡΘΡΙΤΙΔΑ45287,969,5 ΡΕΥΜΑΤΟΕΙΔΗΣ ΑΡΘΡΙΤΙΔΑ457,761,5 ΜΕΤΑΤΡΑΥΜΑΤΙΚΗ ΑΡΘΡΙΤΙΔΑ172,659,2 ΑΛΛΑ ΑΙΤΙΑ121,759,2 ΣΥΝΟΛΟ ,5

ΤΥΠΟΣ ΑΡΘΟΠΛΑΣΤΙΚΗΣ nCEM/EDCEM/LESS CEM/ED TIBIAL TACK8000 LCS GENESIS II M.b

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

Subvastus approach

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

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

Follow up 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

Range of motion

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

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

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