The trochlea is medialized by total knee arthroplasty: an intraoperative assessment in 61 patients.
BACKGROUND
A medialization of the femoral component in a total knee arthroplasty (TKA) causes abnormal patellar tracking, which could result in patellar instability, pain, wear, and failure. Previous reports defined medialization in relation to the neutral position of the femoral component, but omitted to compare it to the anatomical position of the trochlea. We assessed intraoperatively whether there is a systematic error of the position of the prosthetic groove relative to the anatomical trochlea.


METHODS
A special instrument was developed to measure consecutively the mediolateral position of the anatomical trochlea and the mediolateral position of the prosthetic groove. 3 experienced knee surgeons determined the mediolateral error of the prosthetic groove in primary TKAs in 61 patients.


RESULTS
There was a significant medial error of the prosthetic groove relative to the preoperative position of the trochlea, with a mean medial error of 2.5 mm (SD 3.3)


CONCLUSIONS
Our findings indicate that the trochlea is medialized by TKA. Because a conscious medialization of the femoral component in a TKA produces abnormal patellar tracking patterns, further investigations will be needed to analyze the clinical consequences of this medialization of the trochlea.
Meijerink
Huub J
HJ
Department of Orthopaedics, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
Barink
Marco
M
van Loon
Corné J M
CJ
Schwering
Paul J A
PJ
Donk
Roland D
RD
Verdonschot
Nico
N
de Waal Malefijt
Maarten C
MC
D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D001696:Biomechanical Phenomena; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects; D015588:Observer Variation; D010329:Patella / Q000473:pathology / Q000503:physiopathology; D011446:Prospective Studies; D011474:Prosthesis Design; D016059:Range of Motion, Articular