2015 ISAKOS Biennial Congress ePoster #1423
The Change of Joint Line and Its Impact on the Clinical Outcomes in Total Knee Arthroplasty Using Gap Balancing Technique
Hyuk-Soo Han, MD, PhD, Seoul KOREA, REPUBLIC OF
Sang Cheol Seong, MD, PhD, mapo-gu, Seoul city KOREA, REPUBLIC OF
Sahnghoon Lee, MD, PhD, Seoul KOREA, REPUBLIC OF
Kee Yun Chung, Seoul KOREA, REPUBLIC OF
Ki Bum Kim
Myung Chul Lee, MD, PhD, Prof., Seoul KOREA, REPUBLIC OF
Seoul National University College Of medicine, Seoul, 101 DAEHAK-RO JONGNO-GU, KOREA
FDA Status Cleared
Summary: Gap balancing technique can elevate the joint line. Five millimeters or more change of joint line did not deteriorate the clinical outcomes, but decreased the postoperative ROM. The larger preoperative flexion contracture and the decrease of PCO brought the elevation of joint line after the TKA using gap balancing technique.
Gap balancing technique is a well-known surgical technique focused on the symmetry of flexion gap and extension gap. Restoration of joint line (JL) is essential for better clinical outcomes with regard to knee scores and range of motion. The aim of this study was (1) to investigate whether joint line was elevated or not after total knee arthroplasty(TKA) with using gap balancing technique, (2) to determine whether the change of JL affected the clinical outcomes including range of motion (ROM) and clinical scores and (3) to determine the factors causing the elevation of joint line.
One hundred and four knees that underwent TKAs using gap balancing technique with minimum 2 years follow up were enrolled. We respectively measured the JL in weight bearing anteroposterior and 30° flexion true lateral plain radiograph, and collected the data of clinical variables such as ROM, Knee Society knee scores (KSKS), Knee Society function scores (KSFS), Hospital for Special Surgery (HSS) scores, and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index scores. All knees were divided into 2 groups based on the change of JL measured in AP and lateral radiograph (group 1, -5 mm ~ 5 mm; group 2, =-5 mm or = 5 mm). Clinical outcomes between two groups were compared. Multiple linear regression analysis was performed to determine the factors causing the change of joint line.
The level of JL was elevated 1.65 ± 3.26 mm (from -7.93 mm to 10.62 mm) in AP radiographs, 0.78 ± 2.49 mm (from -5.86 mm to 7.35 mm) in lateral radiographs. Five millimeters or more changes of JL were detectable in 14 (13.5%) knees in AP radiographs and 9 (8.7 %) knees in lateral radiographs. There were no significant differences in knee scores (KSKS, KFKS, HSS, and WOMAC) between two groups. However, there was significant difference in the ROM (121.8±11.2° in group 1, 111.3±5° in group 2) between two groups (p=0.01). Preoperative flexion contracture and change of posterior condylar offset (PCO) was found to be an independent predictor of the elevation of joint line. (ß=0.21,-0.34 in AP, ß=0.1,-0.49 in lateral, p < 0.01)
Gap balancing technique can elevate the joint line. Five millimeters or more change of joint line did not deteriorate the clinical outcomes, but decreased the postoperative ROM. The larger preoperative flexion contracture and the decrease of PCO brought the elevation of joint line after the TKA using gap balancing technique.