Biomedical Engineering Reference
In-Depth Information
The hip fusion position was 30
o
flexion, neutral in abduction-adduction and
rotation. He underwent a left knee epiphysiodesis at age 13 to help shorten his left
lower extremity to compensate for the shortened right lower extremity due to his
hip arthrodesis. His current leg length discrepancy was 5 inches (12.7 cm). Pre-
operative X-rays are seen in Fig. 6.110.
Fig. 6.110
AP Pelvis and AP and Lateral X-rays of the Right Knee in a 77 Year Old Man
with Osteoarthritis, Significant Varus Deformity and an Ipsilateral Hip Fusion
6.7.3.2 Procedure
This patient underwent a right cementless B-P total knee replacements on August
16, 2010. A midline skin incision and a deep median parapatellar incision were
used under tourniquet control of 250mm Hg. The medial side of the tibia was
only partially resected, due to a large defect, which was bone grafted. A
significant medial sleeve release was performed to correct the varus deformity.
The tibial resection was perpendicular in the frontal plane and inclined
approximately 7
o
in the lateral plane. A flexion gap was established after the
antenuated cruciate ligaments were resected, using a femoral guide positioner to
externally rotate an intramedullary-fixed femoral resection guide. An extension
gap was produced to equal the flexion gap by resecting the distal femur in
3
o
valgus. Finishing cuts on the femur and tibial stem preparation allowed for
press-fit, porous coated, cementless size 4 components with a 12.5mm size 4
UHMW polyethylene bearing (sterilized with ethylene oxide). Because of mid-
range lateral instability, the ilio-tibial tract was mobilized and sutured to the lateral
border of the patella tendon. The sutures were tied after final implants were
impacted into place. The patella was treated by rim release and rim cautery for
denervation purposes to complete the procedure which underwent routine closure.
6.7.3.3 Post-operative Course
The patient's right knee wound healed slowly over a 4 week period, and his lateral
instability required 6 weeks of a long leg brace with double uprights and a hinged
knee, locked to allow 0
o
to 60
o
motion and set at 3
o
valgus. After brace removal,
excellent collateral stability was observed due to scar tissue formation, despite the
