Is the medial wall of the intercondylar notch useful for tibial rotational reference in unicompartmental knee arthroplasty?
BACKGROUND
It is difficult to implant components in the correct rotational position in the narrow operating field in a unicompartmental knee arthroplasty. Although no rotational reference has been confirmed for unicompartmental knee arthroplasty, the AP axis of the tibia may serve as a reference for unicompartmental knee arthroplasty and TKA. However, it is difficult to identify the AP axis during unicompartmental knee arthroplasty, especially with the tibia first-cut technique.


OBJECTIVE
We explored whether the medial wall of the intercondylar notch could be useful for the tibial rotational reference as an alternative to the AP axis in unicompartmental knee arthroplasty.


METHODS
We scanned the knees of 24 healthy Asian patients (45 knees) at a flexion angle of 90º using open MRI, then measured the angle between the AP axis and the medial wall of the notch. We determined whether the origins of the ACL and PCL were located lateral to the line on the medial wall of the notch and whether the mediolateral dimension of the bone cut surface of the medial tibial plateau was wide enough relative to the AP dimension to use the commercially available unicompartmental knee arthroplasty tibial components when the tibia was cut parallel to the medial wall of the notch.


RESULTS
At 90º flexion the medial wall of the notch was externally rotated 0.1º ± 4.4º relative to the AP axis. In all knees, the ACL and PCL were located lateral to the line on the medial wall of the notch. The mediolateral dimension of the bone cut surface was wide enough to use the commercially available tibial components.


CONCLUSIONS
At 90º flexion the medial wall of the intercondylar notch is almost parallel to the AP axis of the tibia at and we believe a reasonable candidate for a rotational reference of tibial placement in unicompartmental knee arthroplasty. This landmark would need to be confirmed in other populations and in patients with osteoarthritis.
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Shinya
S
Kawahara
Shuichi
S
Matsuda
Ken
K
Okazaki
Yasutaka
Y
Tashiro
Yukihide
Y
Iwamoto
D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D016059:Range of Motion, Articular; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*