Accuracy of computed tomography-based navigation-assisted total knee arthroplasty: outlier analysis

• Published in: The Journal of arthroplasty Vol. 32; no. 1; pp. 47 - 52
• Main Authors: Miyasaka, Teruyuki, MD, Kurosaka, Daisaburo, MD, Saito, Mitsuru, MD, PhD, Omori, Toshiyuki, MD, Ikeda, Ryo, MD, PhD, Marumo, Keishi, MD, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2017
• Subjects: accuracy; Aged; Aged, 80 and over; alignment; Ankle Joint - surgery; Arthroplasty, Replacement, Knee - methods; computer; CT-based navigation; Female; Femur - diagnostic imaging; Femur - surgery; Humans; Knee Joint - diagnostic imaging; Knee Joint - surgery; Male; Middle Aged; Orthopedics; outlier; Patient Positioning; Postoperative Period; Radiography; Retrospective Studies; Surgery, Computer-Assisted - methods; Tibia - surgery; Tomography, X-Ray Computed; total knee arthroplasty; outlier; total knee arthroplasty; accuracy; CT-based navigation; computer; alignment
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2016.05.069

Abstract Background Achieving neutral limb alignment during total knee arthroplasty (TKA) has been identified as a potential factor in long-term prosthesis survival. This study aimed to analyze the accuracy of component orientation and post-operative alignment of the leg following CT-based navigation-assisted TKA, compare these parameters with those of a conventional technique and analyze differences in the data of outliers. Methods We retrospectively compared the alignment of 130 TKAs performed with a CT-based navigation system with that of 67 arthroplasties done with a conventional system. The knee joints were evaluated using radiographs. Results Mean hip-knee-ankle angle, frontal femoral component angle and frontal tibial component angle were 180.7°, 88.8° and 90.6°, respectively, for the navigation-assisted arthroplasties and 181.1°, 88.7° and 90.2°, respectively, for the conventional arthroplasties. All pre-operative leg axes of 10 outliers in the navigation group were >193°, while the data of 17 outliers in the conventional group were scattered. Conclusion This study demonstrates significant improvements in component positioning with the CT-based navigation system. Furthermore, when analyzing cases with pre-operative HKA angles≤192°, no outliers were found in the navigation group, indicating high alignment accuracy. However, in cases with pre-operative HKA angles≥193°, outliers were found in both groups and no significant difference between the groups was observed (p=0.08). Detailed analysis of the outlier cases in the navigation group revealed that the femoral component was placed in the varus position. These findings indicate that the varus knee is an important factor influencing accurate positioning of the femoral component and the post-operative leg axis.