Hiroaki Tsukamoto1, Hidetomo Saito2, Kimio Saito2, Takayuki Yoshikawa3, Masashi Oba4, Kana Sasaki5, Chie Sato5, Manabu Akagawa5, Yasuhiro Takahashi5, Naohisa Miyakoshi6, Yoichi Shimada6. 1. Department of Orthopedic Surgery, Omori Municipal Hospital, Akita, Japan; Department of Orthopedic Surgery, Akita University Graduate School of Medicine, Akita, Japan; Department of Internal Medicine, Tazawako Municipal Hospital, Akita, Japan; Akita Sports Arthroscopy Knee Group (ASAK), Akita, Japan. Electronic address: m06058ht@jichi.ac.jp. 2. Department of Orthopedic Surgery, Akita University Graduate School of Medicine, Akita, Japan; Akita Sports Arthroscopy Knee Group (ASAK), Akita, Japan. 3. Department of Orthopedic Surgery, Omori Municipal Hospital, Akita, Japan; Akita Sports Arthroscopy Knee Group (ASAK), Akita, Japan. 4. Department of Orthopedic Surgery, Omori Municipal Hospital, Akita, Japan. 5. Akita Sports Arthroscopy Knee Group (ASAK), Akita, Japan. 6. Department of Orthopedic Surgery, Akita University Graduate School of Medicine, Akita, Japan.
Abstract
BACKGROUND: Spontaneous osteonecrosis of the knee (SONK) is one of the acute knee pain disorders arising in elderly patients. The presence of knee varus alignment and the size of necrotic area have been reported as the negative prognostic factors in prior studies. However, no previous study has yet clarified the radiological analysis of the lower extremity in SONK compared with that in osteoarthritis. The purpose of this study was therefore to identify the radiographic findings of the lower extremity in SONK. METHODS: Sixty-three knees of Kellgren-Lawrence classification grade 1 or 2 without any trauma treated between April 2012 and March 2014 were enrolled in this study. These knees were divided into two groups according to their magnetic resonance imaging (MRI) findings: SONK group (31 knees) and OA group (32 knees). Using a long leg standing X-ray, femorotibial angle (FTA), mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and joint line convergent angle (JLCA) were compared between groups. Correlation between each parameter and the width ratio (WR) of the necrotic lesion were analyzed. RESULTS: FTA, MAD, MPTA and JLCA showed significant differences between the SONK and OA groups. In the SONK group, FTA was positively correlated with WR, and, MAD and MPTA was negatively correlated with WR. CONCLUSIONS: Compared with OA, SONK is associated with a significantly larger varus deformity at the proximal tibia, and larger joint play in the coronal plane.
BACKGROUND:Spontaneous osteonecrosis of the knee (SONK) is one of the acute knee pain disorders arising in elderly patients. The presence of knee varus alignment and the size of necrotic area have been reported as the negative prognostic factors in prior studies. However, no previous study has yet clarified the radiological analysis of the lower extremity in SONK compared with that in osteoarthritis. The purpose of this study was therefore to identify the radiographic findings of the lower extremity in SONK. METHODS: Sixty-three knees of Kellgren-Lawrence classification grade 1 or 2 without any trauma treated between April 2012 and March 2014 were enrolled in this study. These knees were divided into two groups according to their magnetic resonance imaging (MRI) findings: SONK group (31 knees) and OA group (32 knees). Using a long leg standing X-ray, femorotibial angle (FTA), mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and joint line convergent angle (JLCA) were compared between groups. Correlation between each parameter and the width ratio (WR) of the necrotic lesion were analyzed. RESULTS:FTA, MAD, MPTA and JLCA showed significant differences between the SONK and OA groups. In the SONK group, FTA was positively correlated with WR, and, MAD and MPTA was negatively correlated with WR. CONCLUSIONS: Compared with OA, SONK is associated with a significantly larger varus deformity at the proximal tibia, and larger joint play in the coronal plane.