Our study had a response rate of 88 % at 6 months and 83.7 % at 12 months. Groups at 6 and 12 months had comparable characteristics—115 patients (65 female, 50 male) at 6 months with a mean age of 68 and 82 patients (46 female, 36 male) at 12 months with a mean age of 69. These characteristics are comparable to previous studies on kneeling ability, which ranged in age from 66−72.2 years [11, 12, 15–20].
Patients with osteoarthritis have a poor ability to kneel preoperatively. Although this improves following TKA, patients are still expected to continue to have some difficulty kneeling [12, 21]. Only one small study (n = 58) has previously looked at the effect of education on kneeling post partial knee replacement [20]. This study showed limited but promising evidence that improved perceived kneeling ability was solely associated with receiving kneeling education which included a ‘one-off thirty minute physical therapy intervention and written information on kneeling’. Similar to the present study, patients were told that even though kneeling would be uncomfortable or painful it would not damage the new joint [20]. Our results showed an increase from 6−12 months post TKA in the percentage of patients who reported they could kneel from 63−72 %. In comparison, previous studies have shown kneeling ability with little or no difficultly post TKA to be between 20 and 44 % depending on the study [11, 15, 17, 18], and the percentage of patients who remain unable to kneel in these studies was 15–39 % [11, 15, 18], which is similar to our results (28–36.5 %)
The percentage of patients reporting pain as the reason for not being able to kneel decreased from 24.3 to 17.1 %. Discomfort and pressure as deterring factors at 12 months post TKA increased from 38.3 to 75.6 %. This indicates that the pain experienced by patients post TKA lessens over time and possibly becomes a residual ‘discomfort’ or ‘pressure’ in the knee. Examining discomfort post TKA would be an important area for further analysis in future studies due to the significant number of patients who are deterred from kneeling due to this experience.
There has been a growing recognition in the orthopedic field that patient-centered evaluation tools should be used to evaluate patient outcomes after TKA procedures [8]. We chose to use the OKS [10], developed over a decade ago, and which has since been demonstrated to be a suitable self-assessment tool for TKA evaluation [22, 23]. At 12 months, patients were asked to complete the questionnaire along with their kneeling survey. Consistent with the literature, the poorest reported outcome on the questionnaire was for question 7 ‘Could you kneel down and get up afterwards?’ [12, 16, 17, 24]. The majority of our patients at 12 months reported mild to moderate difficulty with this task.
We analyzed whether the ability of our patients to kneel was related to overall functional scores, pain scores and knee stability scores using the OKS [10]. There was a very strong correlation between kneeling scores and knee function scores (R = 0.70), a strong correlation between kneeling and knee pain (R = 0.45), and a weak relationship between kneeling and knee stability (R = 0.29). Importantly, the weak relationship between kneeling and knee stability in combination with the near perfect (3.8/4) knee stability score demonstrates that the inability of the patients to kneel was not related to an unstable knee. When comparing the scores of the patients who could and could not kneel, significant differences were detected for both standardized pain and function (p = 0.03 and 0.001, respectively). These results are similar to those found in a recent study in Iran for a similar-sized group of patients with osteoarthritis [18].
Previous studies evaluating kneeling ability post knee replacement have identified various factors preventing patients from being able to perform the task. For perceived inability to kneel, reasons included ‘think it may be painful’, ‘have not tried’, ‘been told not to’, ‘think it would be difficult’, ‘afraid of damaging the prosthesis’, ‘did not think they should’, ‘numbness’ and ‘stiffness’. Sixty-three percent gave reasons that could be addressed by education or rehabilitation [16]. Contrary to the common belief of these patients, there is no evidence that kneeling is harmful to the prosthesis [18, 21]. Eight subjects were identified by our patients when asked about other factors preventing them from kneeling in the survey. Importantly, 74 % of the reasons were unrelated to the knee or the surgery, including the most common response of ‘problems with the other knee’. In contrast to previous literature on this topic, only one patient had a reason normally addressed by education, which was ‘could not kneel due to a fear of injuring their knee’ [11].
There are a number of other factors such as numbness, decreased range of motion, gender [16], and choice of surgical techniques [25–27] which are mentioned in previous studies on the topic of evaluating kneeling after knee replacement, which we have not address in our current study, which would be of consideration for future studies on kneeling ability.
There are limitations to this study that need to be acknowledged. This study did not include preoperative scores of pain and functional abilities including ability to kneel. The study included a small sample size, and included patients operated on by only one surgeon at two hospital sites. The amount of information obtained through the survey was limited and may have been better addressed though an interview format. The implementation of these education sessions was not performed with a control group. Therefore, further randomized controlled trials are needed to provide a higher level evidence for this intervention. Finally not all of the patients completed the survey at 12 months.
There are several important conclusions supported by this current study. This is the first study to evaluate the effect of preoperative patient education on kneeling ability post TKA, as recommended in a number of previous studies. Even with appropriate education on kneeling ability, patients identified that pain and discomfort were significant factors preventing them from kneeling post TKA. Patients who had more pain and less overall functional ability were more unlikely to be able to kneel. This study showed an increase in the number of patients able to kneel with little or no difficulty compared to previous studies. Importantly, in contrast to previous studies, only one patient reported their reason for not kneeling as due to a fear of injuring their knee. Therefore, education sessions should be a routine part of the TKA patient journey. Consistent with previous studies, our results show that kneeling continues to be the poorest functional outcome post TKA and therefore an important area for continued research.