Rotational Mismatch of Self-Align Technique in Posterior-Stabilized Total Knee Arthroplasty
Thanainit Chotanaphuti MD1, Montri Choowong MD1, Artit Laoruengthana MD2, Piti Rattanaprichavej MD2
Affiliation : 1 Department of Orthopedics, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand 2 Orthopedic Department, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand
Background : Rotational malalignment of a femoral component may lead to chronic pain, patellar maltracking, knee instability,
and early failure of a total knee arthroplasty [TKA]. The transepicondylar axis of the femur is widely accepted as a good
reference for rotational alignment of a tibial component, although it is more controversial for a tibial component.
Objective : This study aimed to determine the degree of rotational mismatch between femoral and tibial components implanted
using the center-post self-align technique.
Materials and Methods : Patients who underwent TKA for osteoarthritis of the knee were enrolled to have postoperative CT
scans for determination of the rotational alignment. The study included 51 patients (60 knees), 5 males and 46 females, with
a mean age of 64.0 years (range 58 to 73). The posterior cruciate ligament substituting tibial component position was set
using the center-post self-align technique. CT digital images in the supine position with the knee at full extension were
evaluated.
Results : Of the 60 TKAs, the mean rotational mismatch between tibial and femoral prostheses was 2.00° (SD+0.34°, range
0.1° to 5.8°). The femoral component was rotated externally and internally within 1.5° while the tibial component was
within 2.59° relative to the transepicondylar axis. All knees had good patellar tracking intraoperatively without any lateral
release procedure.
Conclusion : The center-post self-align technique can achieve good compatibility of rotational alignment between the
femoral and tibial components with low variability, particularly with the knee in the extended position.
Keywords : Total knee arthroplasty; Rotational alignment of tibial component; Rotational mismatch; Self-align technique; Range of movement technique
