Evaluation of the rotational alignment of the tibial component in total knee arthroplasty: position prioritizing maximum coverage.
BACKGROUND
The standard for rotational alignment of the tibial component in total knee arthroplasty (TKA) remains unclear. Cases often require positioning of the tibial component, prioritizing adequate coverage of resected bone surface rather than alignment with the tibial rotational axis. We investigated tibial component position in TKA, prioritizing maximum coverage of resected bone surface, and evaluated the correlation with the tibial anteroposterior (AP) axis.


METHODS
We analyzed preoperative computed tomography images for primary TKA in 106 cases and 157 knees, using three-dimensional planning software. Tibial component position prioritizing maximum coverage of resected bone surface was simulated, and results were compared with the AP axis. Rotational alignment angle was defined as that between a line perpendicular to the tibial AP axis and a line connecting the posterior edge of the tibial component.


RESULTS
The simulated tibial component was more externally rotated by a mean 4.5° ± 4.2°. The alignment angle showed normal distribution, but variability was large, ranging from 5.1° internal rotation to 16.2° external rotation. In 138 of 157 (87.9 %) knees, the tibial component was positioned in the externally rotated position with respect to the AP axis. The tibial component was aligned within the medial one-third of the patellar tendon in 122 of 157 (77.7 %) knees.


CONCLUSIONS
The tibial component aligned using coverage prioritizing was externally rotated, although large variability was observed. Rotational alignment was optimal in 79 % of cases when the tibial component was aligned with coverage prioritizing, but hyperexternal rotation was observed in patients with severe knee deformation.
Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita, 879-5593, Japan.
Masashi
M
Hirakawa
Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita, 879-5593, Japan. masashim@oita-u.ac.jp.
Masashi
M
Miyazaki
Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita, 879-5593, Japan.
Shinichi
S
Ikeda
Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita, 879-5593, Japan.
Yoshiki
Y
Matsumoto
Center for Joint Replacement Surgery, Kishigawa Rehabilitation Hospital, Wakayama, Japan.
Makoto
M
Kondo
Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu-shi, Oita, 879-5593, Japan.
Hiroshi
H
Tsumura
D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D017760:Bone Malalignment / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery; D017847:Patellar Ligament / Q000000981:diagnostic imaging; D016119:Posterior Cruciate Ligament / Q000000981:diagnostic imaging; D011300:Preoperative Care; D012399:Rotation; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
Computed tomography; Rotational alignment; Tibial component; Total knee arthroplasty