Biomedical Engineering Reference
In-Depth Information
Note the change in bearing height after her 20 year revision procedures.
6.7.1.4 Authors' Insights
Cementless rotating platforms maintain fixation and perform well in osteoporotic,
rheumatoid bone over the long term (as seen in this case). Despite improved
surface congruity, these gamma-in-air sterilized bearings wore significantly over a
20 year period, causing synovitis and osteolysis, which has been seen much earlier
in fixed-bearing designs using the same sterilization methods. Bearing exchange
revision and bone graft of osteolytic defects allows maintenance of these well-
fixed devices and a return to earlier function than full revision of all components.
6.7.2 Case Report #2
Mark I Rotating-Platform TKR (LCS) Versus Mark III Rotating-Platform TKR
(B-P) (Semi-constrained mobile-bearing for use in bicompartmental or
tricompartmental disease with intact collateral ligaments).
6.7.2.1 History
A 60 year old, 230 pound (103 kg), 5 foot 9 inch (175 cm) tall, white male and
avid golfer developed intractable pain, stiffness and crepitus in both knees over a 3
year period due to advanced osteoarthritis. His right knee had an open medial
menisectomy 20 years ago, and developed a 5
o
varus deformity and a 15
o
flexion
contracture, but further flexed to 120
o
. His left knee had no previous surgery but
developed a similar 5
o
varus deformity and similar range of motion (15
o
to 120
o
).
Pre-operative X-rays are seen in Fig. 6.108.
Fig. 6.108
AP X-rays in a 60 Year Old Man with Severe Osteoarthritis and Fixed-Varus
Deformities
