Yuichi Kuroda1, Kazunari Ishida2, Tomoyuki Matsumoto3, Hiroshi Sasaki4, Tokio Matsuzaki3, Shinya Oka3, Koji Takayama3, Katsumasa Tei5, Takehiko Matsushita3, Nobuhiro Tsumura1, Ryosuke Kuroda3, Masahiro Kurosaka3. 1. Department of Orthopaedic Surgery, Hyogo Rehabilitation Center Hospital, Kobe, Japan. 2. Department of Orthopaedic Surgery, Kobe Kaisei Hospital, 3-11-15, Shinohara-Kita, Nada, Kobe, 657-0068, Japan. wavedreamer17@yahoo.co.jp. 3. Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan. 4. Department of Orthopaedic Surgery, Kobe Kaisei Hospital, 3-11-15, Shinohara-Kita, Nada, Kobe, 657-0068, Japan. 5. Department of Orthopaedic Surgery, Chibune General Hospital, Osaka, Japan.
Abstract
PURPOSE: The sagittal fibular axis serves as an intra-operative landmark during conventional total knee arthroplasty (TKA); however, only a few relevant anatomical studies have been published regarding its use as an extramedullary guide. Furthermore, the correlation between the coronal fibular and tibial mechanical axes in osteoarthritic knees has been only reported once. Here, the hypothesis of this study is that the fibula can be a reliable intra-operative landmark, in the sagittal and coronal planes, among patients with osteoarthritis who have undergone TKA. METHODS: Osteoarthritic knees (n = 62) after TKA were evaluated using three-dimensional image-matching software. The angles between the tibial mechanical axis and the fibular shaft axis were measured in the sagittal and coronal planes. Moreover, correlations between the angles and patient-specific factors were evaluated. RESULTS: The mean angle between the tibial mechanical and fibular shaft axes was 2.6° ± 2.3° for posterior inclination in the sagittal plane and 0.9° ± 2.0° for varus inclination in the coronal plane. The percentage of subjects with the fibular shaft axis within 2° of the tibial mechanical axis was 17.7 and 69.3 % in the sagittal and coronal planes, respectively. No patient-specific factors were correlated with the angle between the tibial mechanical and fibular shaft axes. CONCLUSIONS: The angle between the tibial mechanical and fibular shaft axes differed among patients, independent of patient-specific factors, and did not appear to be a reliable intra-operative landmark. Surgeons should use values from individual pre-operative evaluations of the axis as reference for conventional TKA. LEVEL OF EVIDENCE: Case series with no comparison group, Level IV.
PURPOSE: The sagittal fibular axis serves as an intra-operative landmark during conventional total knee arthroplasty (TKA); however, only a few relevant anatomical studies have been published regarding its use as an extramedullary guide. Furthermore, the correlation between the coronal fibular and tibial mechanical axes in osteoarthritic knees has been only reported once. Here, the hypothesis of this study is that the fibula can be a reliable intra-operative landmark, in the sagittal and coronal planes, among patients with osteoarthritis who have undergone TKA. METHODS: Osteoarthritic knees (n = 62) after TKA were evaluated using three-dimensional image-matching software. The angles between the tibial mechanical axis and the fibular shaft axis were measured in the sagittal and coronal planes. Moreover, correlations between the angles and patient-specific factors were evaluated. RESULTS: The mean angle between the tibial mechanical and fibular shaft axes was 2.6° ± 2.3° for posterior inclination in the sagittal plane and 0.9° ± 2.0° for varus inclination in the coronal plane. The percentage of subjects with the fibular shaft axis within 2° of the tibial mechanical axis was 17.7 and 69.3 % in the sagittal and coronal planes, respectively. No patient-specific factors were correlated with the angle between the tibial mechanical and fibular shaft axes. CONCLUSIONS: The angle between the tibial mechanical and fibular shaft axes differed among patients, independent of patient-specific factors, and did not appear to be a reliable intra-operative landmark. Surgeons should use values from individual pre-operative evaluations of the axis as reference for conventional TKA. LEVEL OF EVIDENCE: Case series with no comparison group, Level IV.