- Discussion:
-
quantification of joint line malposition:
- joint line position lies about 3 cm distal to the medial femoral epicondyle and 15 mm above the fibular head;
- if the opposite knee has not undergone TKR then measure the distance from the adductor tubercle to the distal edge of the femoral component;
- if the opposite knee has undergone previous TKR (or has deformity) then the optimal joint line position often lies two finger breadths above the tibial tubercle;
- at the time of surgery, the joint line position can be determined by looking for the old residual meniscus;
-
elevation of joint line:
- common complication with primary and especially revision total knee replacement;
-
patella baja results from elevation of the joint line;
-
lowering of the joint line:
-
depth of tibial cut:
- occurrs if tibial resection is made very distal & amount of femur resected was less than the thickness of component being used;
- in this situation the knee is stable in extension but becomes progressively lax as it is flexed;
- this situation occurs most often when, in the face of an asymmetrical tibial plateau defect, the surgeon attempts to obtain a flat tibial
surface by lowering the tibial resection line;
The influence of patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis.
HE Figgie et al.
JBJS Vol 68-A 1986. p 1035-1040.
Joint line displacement of a total knee replacement results in reduction of knee flexion.
JF Cummings et al.
Trans. Orthop. Res. Soc.
Vol 15. 1990. p 280.
Joint line position restoration during revision total knee replacement.
