International Orthopaedics (SICOT) DOI 10.1007/s00264-015-2710-1
ORIGINAL PAPER
Factors affecting range of motion after total knee arthroplasty in patients with more than 120 degrees of preoperative flexion angle Kazuya Sugitani & Yuji Arai & Hisatake Takamiya & Ryu Terauchi & Shuji Nakagawa & Keiichiro Ueshima & Toshikazu Kubo
Received: 3 February 2015 / Accepted: 10 February 2015 # SICOT aisbl 2015
Abstract Purpose The postoperative flexion angle reportedly shows a positive correlation with the preoperative flexion angle, but in some cases, the postoperative flexion angle decreases in patients with a large preoperative flexion angle. The purpose of this study was to investigate factors affecting the range of motion after total knee arthroplasty (TKA) in patients with a large preoperative flexion angle. Methods The study evaluated 120 knees with more than 120 degrees of preoperative flexion angle that underwent NexGen LPS-Flex mobile bearing. The groups with and without a reduction in the postoperative flexion angle were compared. Also, a logistic regression analysis was performed, where the presence or absence of a reduction in the postoperative flexion angle was the dependent variable and age, sex, body mass index (BMI), preoperative femorotibial angle (FTA), γ angle, δ angle, pre/postoperative change amount in posterior condylar offset (PCO), pre/postoperative change amount in joint line, and pre/postoperative change amount in patellar thickness were independent variables. Results Those with preoperative FTA of 186° or larger did not have a reduction in the postoperative flexion angle, compared with the angle of 185° or smaller. Those with δ angle of 83° or smaller also did not have a reduction in the postoperative flexion angle, compared with the angle of 84° or larger. K. Sugitani : Y. Arai (*) : H. Takamiya : R. Terauchi : S. Nakagawa : K. Ueshima : T. Kubo Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan e-mail: [email protected] K. Sugitani e-mail: [email protected]
Conclusions Our results showed that preoperative FTA and δ angle had an impact on a reduction in the postoperative flexion angle. The installation angle of the tibial component in the sagittal plane is important. Keywords Range of motion . Total knee arthroplasty . Posterior tibial slope . Varus deformity . Posterior condylar offset
Introduction Total knee arthroplasty (TKA) has been widely implemented in recent years as a surgical treatment for osteoarthritis of the knee, and favourable long-term outcomes have been reported. TKA is one of the most useful procedures for osteoarthritis of the knee in terms of durability and pain relief. When an adequate postoperative flexion angle cannot be obtained, however, this limits the activities of daily living and lowers patient satisfaction. A limited flexion angle represents a hindrance to activities of daily living, and patients have low satisfaction when their activity is even lower than before surgery or when they are unable to enjoy anticipated activities [1, 2]. It is a critically important factor in patient satisfaction to maintain or even enhance the flexion angle after TKA. The postoperative flexion angle reportedly shows a positive correlation with the preoperative flexion angle [3, 4], but in some cases, the postoperative flexion angle increases in patients with a small preoperative flexion angle and it decreases in patients with a large preoperative flexion angle. In order to further improve the results of TKA, it is considered important not to reduce the postoperative flexion angle for patients with a large preoperative flexion angle.
International Orthopaedics (SICOT)
The purpose of this study was to investigate factors affecting the range of motion after TKA in patients with more than 120 degrees of preoperative flexion angle.
Materials and methods The study evaluated 120 knees (27 male, 93 female) with more than 120 degrees of preoperative flexion angle that underwent TKA at our hospital. The patients had a mean age of 74.5±7.5 years, mean body mass index (BMI) of 25.5 ± 3.8 kg/m², and mean follow-up period of 37.5 ± 25.9 months. All patients had medial osteoarthritis of the knee, and TKA was performed using NexGen LPS-Flex mobile bearing (Zimmer, Warsaw, IN). Osteotomy was performed with measured resection, and soft tissue balance was adjusted to reach a rectangle with 0° extension and 90° flexion. However, several degrees of lateral laxity were allowed, because excessive detachment of medial tissue poses the risks of medial instability. The A-group was the group for which the postoperative flexion angle was not reduced compared with the preoperative angle, and the B-group was the group for which it was reduced compared with the preoperative angle. The patient background (age, sex, BMI, follow-up period), knee range of motion, Knee Society score [5], femorotibial angle (FTA), implant installation angles (Fig. 1) [6], posterior condylar offset (PCO), joint line, and patellar thickness were measured for both groups. FTA was measured as the lateral angle formed by the femoral and tibial anatomical axes on the standing anteroposterior radiographs of the whole lower extremity. PCO was measured according to the report by Bellemans et al. [7], where it is the maximal thickness of the posterior condyle, projected posteriorly to the tangent of the posterior cortex of the femoral shaft on the lateral radiographs. The joint line was measured according to the report by Figgie et al. [8],
Fig. 1 Implant installation angles
where it is the perpendicular distance from the tibial tubercle to a line parallel to the weight-bearing surface of the tibial plateau on the preoperative lateral radiographs or the tibial prosthesis on the postoperative lateral radiographs. Measuring the PCO, joint line, and patellar thickness entailed identifying the magnifying power from the anteroposterior diameter of the femoral component on the postoperative lateral radiographs and correcting the postoperative measured values. Also, the preoperative values of them were measured and corrected, using a reference measurement of the diameter of the femoral shaft on the lateral radiographs. Ethical approval for this study was obtained from the Ethical Review Board of our hospital. Statistical analysis All data were expressed as means±standard deviation. The Mann–Whitney U test was used to compare preand postoperative results and the A- and B-groups. The chi-square test was used to compare sex ratios between the two groups, and the correlations of pre- and postoperative flexion angles were tested using Spearman’s rank correlation coefficient. Analysis of the factors affecting a reduction in the postoperative flexion angle involved a logistic regression analysis where the presence or absence of a reduction in the postoperative flexion angle was the dependent variable and age, sex, BMI, preoperative FTA, γ angle, δ angle, pre/ postoperative change amount in PCO, pre/postoperative change amount in joint line, and pre/postoperative change amount in patellar thickness were independent variables. The analysis was conducted using EkuseruToukei (SSRI Co., Ltd., Tokyo, Japan), and p value
ORIGINAL PAPER
Factors affecting range of motion after total knee arthroplasty in patients with more than 120 degrees of preoperative flexion angle Kazuya Sugitani & Yuji Arai & Hisatake Takamiya & Ryu Terauchi & Shuji Nakagawa & Keiichiro Ueshima & Toshikazu Kubo
Received: 3 February 2015 / Accepted: 10 February 2015 # SICOT aisbl 2015
Abstract Purpose The postoperative flexion angle reportedly shows a positive correlation with the preoperative flexion angle, but in some cases, the postoperative flexion angle decreases in patients with a large preoperative flexion angle. The purpose of this study was to investigate factors affecting the range of motion after total knee arthroplasty (TKA) in patients with a large preoperative flexion angle. Methods The study evaluated 120 knees with more than 120 degrees of preoperative flexion angle that underwent NexGen LPS-Flex mobile bearing. The groups with and without a reduction in the postoperative flexion angle were compared. Also, a logistic regression analysis was performed, where the presence or absence of a reduction in the postoperative flexion angle was the dependent variable and age, sex, body mass index (BMI), preoperative femorotibial angle (FTA), γ angle, δ angle, pre/postoperative change amount in posterior condylar offset (PCO), pre/postoperative change amount in joint line, and pre/postoperative change amount in patellar thickness were independent variables. Results Those with preoperative FTA of 186° or larger did not have a reduction in the postoperative flexion angle, compared with the angle of 185° or smaller. Those with δ angle of 83° or smaller also did not have a reduction in the postoperative flexion angle, compared with the angle of 84° or larger. K. Sugitani : Y. Arai (*) : H. Takamiya : R. Terauchi : S. Nakagawa : K. Ueshima : T. Kubo Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan e-mail: [email protected] K. Sugitani e-mail: [email protected]
Conclusions Our results showed that preoperative FTA and δ angle had an impact on a reduction in the postoperative flexion angle. The installation angle of the tibial component in the sagittal plane is important. Keywords Range of motion . Total knee arthroplasty . Posterior tibial slope . Varus deformity . Posterior condylar offset
Introduction Total knee arthroplasty (TKA) has been widely implemented in recent years as a surgical treatment for osteoarthritis of the knee, and favourable long-term outcomes have been reported. TKA is one of the most useful procedures for osteoarthritis of the knee in terms of durability and pain relief. When an adequate postoperative flexion angle cannot be obtained, however, this limits the activities of daily living and lowers patient satisfaction. A limited flexion angle represents a hindrance to activities of daily living, and patients have low satisfaction when their activity is even lower than before surgery or when they are unable to enjoy anticipated activities [1, 2]. It is a critically important factor in patient satisfaction to maintain or even enhance the flexion angle after TKA. The postoperative flexion angle reportedly shows a positive correlation with the preoperative flexion angle [3, 4], but in some cases, the postoperative flexion angle increases in patients with a small preoperative flexion angle and it decreases in patients with a large preoperative flexion angle. In order to further improve the results of TKA, it is considered important not to reduce the postoperative flexion angle for patients with a large preoperative flexion angle.
International Orthopaedics (SICOT)
The purpose of this study was to investigate factors affecting the range of motion after TKA in patients with more than 120 degrees of preoperative flexion angle.
Materials and methods The study evaluated 120 knees (27 male, 93 female) with more than 120 degrees of preoperative flexion angle that underwent TKA at our hospital. The patients had a mean age of 74.5±7.5 years, mean body mass index (BMI) of 25.5 ± 3.8 kg/m², and mean follow-up period of 37.5 ± 25.9 months. All patients had medial osteoarthritis of the knee, and TKA was performed using NexGen LPS-Flex mobile bearing (Zimmer, Warsaw, IN). Osteotomy was performed with measured resection, and soft tissue balance was adjusted to reach a rectangle with 0° extension and 90° flexion. However, several degrees of lateral laxity were allowed, because excessive detachment of medial tissue poses the risks of medial instability. The A-group was the group for which the postoperative flexion angle was not reduced compared with the preoperative angle, and the B-group was the group for which it was reduced compared with the preoperative angle. The patient background (age, sex, BMI, follow-up period), knee range of motion, Knee Society score [5], femorotibial angle (FTA), implant installation angles (Fig. 1) [6], posterior condylar offset (PCO), joint line, and patellar thickness were measured for both groups. FTA was measured as the lateral angle formed by the femoral and tibial anatomical axes on the standing anteroposterior radiographs of the whole lower extremity. PCO was measured according to the report by Bellemans et al. [7], where it is the maximal thickness of the posterior condyle, projected posteriorly to the tangent of the posterior cortex of the femoral shaft on the lateral radiographs. The joint line was measured according to the report by Figgie et al. [8],
Fig. 1 Implant installation angles
where it is the perpendicular distance from the tibial tubercle to a line parallel to the weight-bearing surface of the tibial plateau on the preoperative lateral radiographs or the tibial prosthesis on the postoperative lateral radiographs. Measuring the PCO, joint line, and patellar thickness entailed identifying the magnifying power from the anteroposterior diameter of the femoral component on the postoperative lateral radiographs and correcting the postoperative measured values. Also, the preoperative values of them were measured and corrected, using a reference measurement of the diameter of the femoral shaft on the lateral radiographs. Ethical approval for this study was obtained from the Ethical Review Board of our hospital. Statistical analysis All data were expressed as means±standard deviation. The Mann–Whitney U test was used to compare preand postoperative results and the A- and B-groups. The chi-square test was used to compare sex ratios between the two groups, and the correlations of pre- and postoperative flexion angles were tested using Spearman’s rank correlation coefficient. Analysis of the factors affecting a reduction in the postoperative flexion angle involved a logistic regression analysis where the presence or absence of a reduction in the postoperative flexion angle was the dependent variable and age, sex, BMI, preoperative FTA, γ angle, δ angle, pre/ postoperative change amount in PCO, pre/postoperative change amount in joint line, and pre/postoperative change amount in patellar thickness were independent variables. The analysis was conducted using EkuseruToukei (SSRI Co., Ltd., Tokyo, Japan), and p value
