Date Published: October 11, 2018
Publisher: Public Library of Science
Author(s): Seung Ah Lee, Seung-Baik Kang, Chong Bum Chang, Moon Jong Chang, Young Jun Kim, Min Kyu Song, Jin Hwa Jeong, Daniel Pérez-Prieto.
The purpose of this study was to assess the overall clinical results and range of motion (ROM) after total knee arthroplasty (TKA) in patients with preoperative stiffness. We also aimed to determine whether the severity or cause of the stiffness can affect the clinical outcome after surgery. This retrospective study included 122 knees (117 patients) with follow-up of more than 2 years (mean age, 64.3 years). TKA was performed using posterior-stabilized, varus-valgus constrained (VVC), and hinged prostheses. To determine the effect of the severity of stiffness on the clinical outcome, the subjects were divided into two groups: the severe group (preoperative ROM ≤ 50°; 18 knees) and the moderate group (preoperative ROM, 50°–90°; 104 knees). Then, clinical results and ROM were compared according to the severity or cause of preoperative stiffness. After surgery, preoperative ROM (mean, 78°; range, 25°- 90°) was improved (mean, 107°; range, 70°- 130°). The severe group more frequently used the VVC or hinged prostheses (72% vs. 18%). Furthermore, the severe group had worse knee and function scores as well as more complications (33% vs. 13%), even though the severe group had a greater ROM increment (47° vs. 27°) after surgery. Patients with osteoarthritis and rheumatoid arthritis showed better ROM and clinical results compared to patients with infectious or traumatic arthritis. Although TKA in stiff knees can be successful, the results are inferior in knees with severe stiffness and knees with infectious or traumatic arthritis.
The main goals of total knee arthroplasty (TKA) are pain relief and functional improvement . The majority of patients achieve these goals after surgery. However, a subset of patients are not satisfied with their surgical results . In these patients, limited range of motion (ROM) after surgery can be one of the reasons for dissatisfaction [2–4]. Currently, in most studies, ROM is greater than in earlier reports, probably because of improved surgical techniques and newer prostheses [2,5]. However, postoperative ROM limitation still remains as an issue to be solved in TKA.
This retrospective study included 122 knees with follow-up of more than 2 years. From March 2005 to March 2012, 1859 TKAs were performed at our institution. We defined preoperative stiffness as a ROM of knee joint ≤ 90° . Among the patients who underwent TKA, there were 134 knees (117 patients) with the ROM ≤ 90°. These 134 knees accounted for 7% of the total TKAs performed at our institution during that period. Of these, 122 knees (107 patients) with follow-up of more than 2 years were included in the present study. Twelve knees (9%) were excluded because they were lost to follow-up. The causes of stiffness were osteoarthritis in 80 knees (66%), rheumatoid arthritis in 12 knees (10%), infectious arthritis in 25 (20%), and traumatic arthritis in 5 (4%). No patient with previous infection had ongoing infection before TKA. The presence or absence of residual infection was screened using preoperative symptoms and laboratory tests including levels of erythrocyte sedimentation rate and C-reactive protein. Mean preoperative ROM was 78° (range, 25°- 90°). There were 25 males (29 knees) and 82 females (93 knees) with a mean age of 64.3 years (range, 43 years—83 years) at the time of surgery. Mean body mass index (BMI) of the patients was 27.1 kg/m2. This study protocol was approved by the Institutional Review Board of the SMG-SNU Boramae Medical Center (16-2016-132). All patients gave their consent for using and assessing their data.
Clinical outcome after TKA in patients with stiff knees improved after surgery in terms of ROM and knee and function scores (Table 2). Preoperative ROM (mean, 78°; range, 25°- 90°) substantially improved after surgery (mean, 107°; range, 70°- 130°). The mean amount of ROM increment was 30° (range, 0°- 60°), and 58 knees (48%) had ROM greater than 110°. Stiffness recurred in seven knees (6%). The clinical scores evaluated including KS knee scores, functional scores and WOMAC total scores were substantially improved. The mean KS knee score was improved from 43 points before TKA to 77 points after surgery. The mean WOMAC total score was also improved from 43 points to 21 points after surgery.
In the present study, we hypothesized that clinical outcomes including ROM, knee score, and function score could be substantially improved in contemporary TKA despite stiffness (ROM ≤ 90°) before TKA. We also hypothesized that clinical outcome would differ according to the severity and causative disease of preoperative stiffness. The principal finding of this study was that TKA substantially improved ROM and functional scores in the patients with preoperative stiffness. We also found that the severe stiffness group had more ROM gain than the moderate group. Nonetheless, the final ROM and clinical scores of the severe group were inferior, with a higher complication rate than in the moderate group. In addition, the stiffness caused by infectious and traumatic arthritis was associated with worse clinical outcomes after surgery. In multiple regression analysis, preoperative ROM and cause of stiffness were related to postoperative ROM. Our findings suggest that TKA can improve ROM and functional scores even in the presence of severe preoperative stiffness, but surgeons should be cautious about inferior outcome in patients with more severe preoperative stiffness and the stiffness caused by infectious and traumatic arthritis.
Total knee arthroplasty improves ROM and clinical results after surgery in patients with preoperative stiffness. However, the clinical outcome was inferior in knees with more severe preoperative stiffness or stiffness caused by secondary arthritis such as infectious arthritis and traumatic arthritis. For those patients, special measures such as active physical therapy may be necessary. In addition, the findings of this study should be used to counsel patients before performing TKA in knees with preoperative stiffness.