The evaluation of post-operative alignment in total knee replacement using a CT-based navigation system

Abstract

We compared the alignment of 39 total knee replacements implanted using the conventional alignment guide system with 37 implanted using a CT-based navigation system, performed by a single surgeon. The knees were evaluated using full-length weight-bearing anteroposterior radiographs, lateral radiographs and CT scans. The mean hip-knee-ankle angle, coronal femoral component angle and coronal tibial component angle were 181.8 degrees (174.2 degrees to 188.3 degrees), 88.5 degrees (84.0 degrees to 91.8 degrees) and 89.7 degrees (86.3 degrees to 95.1 degrees), respectively for the conventional group and 180.8 degrees (178.2 degrees to 185.1 degrees), 89.3 degrees (85.8 degrees to 92.0 degrees) and 89.9 degrees (88.0 degrees to 93.0 degrees), respectively for the navigated group. The mean sagittal femoral component angle was 85.5 degrees (80.6 degrees to 92.8 degrees) for the conventional group and 89.6 degrees (85.5 degrees to 94.0 degrees) for the navigated group. The mean rotational femoral and tibial component angles were -0.7 degrees (-8.8 degrees to 9.8 degrees) and -3.3 degrees (-16.8 degrees to 5.8 degrees) for the conventional group and -0.6 degrees (-3.5 degrees to 3.0 degrees) and 0.3 degrees (-5.3 degrees to 7.7 degrees) for the navigated group. The ideal angles of all alignments in the navigated group were obtained at significantly higher rates than in the conventional group. Our results demonstrated significant improvements in component positioning with a CT-based navigation system, especially with respect to rotational alignment.

Pelvic Deformity Influences Acetabular Version and Coverage in Hip Dysplasia

“…Patients in the control group had no degenerative changes or other hip abnormalities. We examined AP pelvic radiographs and pelvic CT images obtained during planning for TKA using a CT-based navigation system [24]. This study was approved by the institutional review board of Kyushu University Hospital.…”

Acetabular Tilt Correlates with Acetabular Version and Coverage in Hip Dysplasia

“…There were 23 right hips and 17 left hips with a mean LCE of 37°(range, 25-42°). These pelvic CT images were obtained as part of a preoperative examination for TKA using a CT-based navigation system [25]. Although the control group was older (p \ 0.0001) than the DDH group, control subjects had no degenerative changes or other hip abnormalities on radiographic and CT examination and were deemed suitable for morphologic examination.…”

Reliability of frames of reference used for tibial component rotation in total knee arthroplasty

“…They described five techniques for landmark data collection using a navigation system to control the tibial rotation alignment and none of them showed any advantages over the others [1]. The large variation in tibial landmarks has been noted by others; for example, Mizu-uchi et al found a large variation in the ideal angle of tibial alignment in their CT-based navigation system study [19].…”