The effect of medial condylar bone loss of the knee on coronal plane stability--a cadaveric study.
BACKGROUND
The quantitative effects of medial bone loss of the knee on both leg alignment and coronal plane stability are poorly understood.


METHODS
Utilizing computer navigation, 5mm bone defects of the medial distal femur (MDF), medial posterior femoral condyle (MPF), and medial tibial plateau (MT) were simulated in 10 cadaveric limbs, and alignment of the knee at various degrees of flexion were analyzed when applying standardized varus and valgus loads.


RESULTS
The 5mm MPF defect significantly increased varus laxity at 90° of flexion by 3.3° ± 1.2° (p=0.019), a 5mm MDF defect resulted in a 2.2° ± 1.7° (p=0.037) and a 2.1° ± 1.3° (p=0.023) increase in laxity at 0° and 30° of flexion, respectively, and a 5mm MT defect increased varus laxity at all flexion angles by 4.0° to 7.0°, but was only statistically significant at 30° (p=0.026).


CONCLUSIONS
This study confirms and quantifies the theories of flexion and extension gap balancing, and pseudolaxity of the medial collateral ligament in the varus knee, the results of which can be used in preoperative planning and intraoperative decision making for both total knee and unicondylar arthroplasty.
Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA.
Denis
D
Nam
Michael B
MB
Cross
Christopher
C
Plaskos
Seth
S
Sherman
David J
DJ
Mayman
Andrew D
AD
Pearle
D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D005269:Femur / Q000473:pathology / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D010024:Osteoporosis / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology*; D013977:Tibia / Q000473:pathology / Q000601:surgery