Expectations of younger patients concerning activities after knee arthroplasty: are we asking the right questions?

Both total knee arthroplasty (TKA) and uniconcylar knee arthroplasty (UKA) are performed at younger ages than before [1‐4] since they are well-accepted, reliable, cost-effective and suitable surgical procedures for end-stage knee osteoarthritis (OA) [5, 6]. Arthroplasty surgery was originally conceived for elderly patients performing activities at low levels. In these early days younger age was even a strict contraindication [7]. Over time indications have expanded to younger and more active patients. Riddle et al. [8] showed that nowadays in the decision-making process for TKA, other factors, such as severity of OA, are considered to play a more important role than age. The volume of TKA-surgeries has increased worldwide, like in the USA up to 200 % over the past decade. Patients younger than 65 years are projected to contribute to the majority of this growth, accounting for more than 55 % of all TKAs in the year 2030 [7, 9]. According to the last annual report of the Dutch Arthroplasty Register (LROI), in The Netherlands, the number of registered KAs has also increased (from 20,558 in 2010 to 26,754 in 2014). In 2014, already 23 % of KAs were performed in patients younger than 60 years old (http://​www.​lroi.​nl/​en/​home).

Knee arthroplasty (KA) is proven to relieve pain, to return to function and to improve health-related quality of life [10, 11]. Despite these positive effects of KA, still 17–19 % of patients are not satisfied after surgery [12, 13]. Residual symptoms have been identified as an important factor in dissatisfaction, for which mostly no implant-related mechanical failure can be found [14‐16]. Chronic pain after KA and other medical, socio-demographic, psychological and biological factors are possible explanatory factors [17, 18], but even when no pain exists and physical functional outcomes are good, still some patients are dissatisfied after KA [15]. Hence, preoperative expectations may also play a role [18‐25]. Young age is associated with high preoperative expectations concerning activities after KA [26, 27]. These high preoperative expectations do not predict satisfaction after joint replacement [26], but fulfilment of these patient expectations clearly seems to play an important role in patient satisfaction [19]. Current described percentages of fulfilment of expectations after KA range from 100 % satisfaction regarding knee pain alleviation to only about 20 % concerning the ability to participate in sports and leisure activities [28].

In younger patients, mostly excellent results of Patient-Reported Outcome Measures (PROMs) after KA are in contrast with more modest satisfaction scores [2, 9, 29‐31]. The Oxford Knee Score (OKS) and EuroQol (EQ-5D) for example, demonstrate good results, but due to lower satisfaction scores there are concerns about existing—so-called—ceiling effects of these PROMs in younger patients. A ceiling effect occurs when a measure possesses a distinct upper limit for potential responses and a large percentage of participants score at or near this limit. As a consequence, patients with the highest possible score cannot be distinguished from each other, thus reliability is reduced [32]. An example of a ceiling effect is if more than 15 % of the participants with the same maximum VAS satisfaction score of 100 might have different levels of satisfaction, which cannot be specified by the instrument any further. In that case, the instrument does not have sufficient power to specify different levels of the construct that it is supposed to measure [32, 33]. Regarding the OKS and EQ-5D in younger patients, this would mean that the highest scores are easily reached, although these highest PROM scores do not necessarily reflect the scores of which the younger patient group would be satisfied with [32]. Patients likely expect to perform more, better or different activities than those incorporated in these PROMs, so the ‘content validity’ of these PROMs for this specific patient group is questionable [34]. Therefore, new PROMS were recently developed for younger, active and working KA patients, like the Work, Osteoarthritis or joint-Replacement Questionnaire (WORQ) [33], the broadened New Knee Society Knee Scoring System (New KSS) [35, 36] and the Oxford Knee Score Activity and Participation Questionnaire (OKS-APQ) [37], which is a supplement to the original OKS.

In summary, two gaps in knowledge were encountered, leading to the following two research questions: ‘What are the actual expectations of OA patients younger than 65 years concerning activities in daily life, work and leisure time after KA?’ and ‘To what extent do current PROMs meet and evaluate these activities of importance in younger KA patients younger than 65 years?’ The aim of our study was (1) to identify patient expectations concerning activities after KA and (2) to determine which current PROMs encompass these expectations best.

Meeting patient expectations is of utmost importance to satisfy patients after KA. In order to make a major step forwards in meeting patient expectations, the current study was designed to explore preoperative expectations concerning activities of younger age knee OA patients awaiting KA. Our results show that younger OA patients expect to perform 16 categories of activities better after KA, subdivided in 162 different forms, circumstances and intensities, mostly indicating the wish for an active lifestyle. Of these, 45 % were activities to perform in daily life, 33 % during work and 50 % during leisure time, making the last category most diverse in forms, circumstances and intensities. By the total mean mW scores, the survey showed that activities of daily living, work and leisure time are of similar importance to younger patients in the decision-making process whether or not wanting to proceed with knee arthroplasty. Furthermore, all seven evaluated PROMs incorporate important activities, but not one PROM incorporates all activities rated of high importance. Moreover, regarding the large SDs of average importance scores, no PROM incorporates only activities rated of high importance.

Our results confirm that younger OA patients expect to perform a diversity of activities better after KA [3, 4]. In line with previous studies, we found that expectations between patients vary, depending on their type of work and preferred life styles [46, 47]. From the literature, we also know that patients’ and surgeons’ expectations can differ. Ghomrawi et al. [48] found that more than 50 % of patients had higher expectations than their surgeons, mostly driven by expectations of high-level activities and extreme ranges of motion. With regard to sports, our focus group study shows that active younger patients expect to perform a diversity of high- and intermediate-impact sports after KA. We recently performed a systematic review concerning return to sports after KA [49]. Although more likely after UKA than after TKA, and possibly with some modifications, we showed that high expectations are not always unrealistic, as some patients were able to return to intermediate and high-impact types of sports [49]. Moreover, also the mentioned low-impact sports varied in intensity, so when not sorted in detail, a higher level of performance can be expected by the patient than by the surgeon [50, 51]. It goes without saying that ‘cycling’ challenging mountain bike trails every week leads to higher impacts to the knee than ‘cycling’ just a short distance on a city bike once in a while.

Understanding the multifactorial patients’ decision-making and their motivation for surgery plays a central role in patient-centred care. In a recent systematic review, ‘expectations’ were mentioned as one of ten important themes [12]. In our study, we further explored these expectations regarding activities. In general, daily life activities and work-related activities appear to be a bit more relevant in the decision-making for surgery than leisure time activities. Concerning the surgeons’ part of the shared decision-making process, Iorio et al. already recognized that for selection of the most suitable implant for the patient, it is important to take into account what activities patients want to perform after KA [52, 53]. Many promising technological innovations in knee implants are being developed for patients who wish to stay more active, like renewed interest in the bicruciate retaining KA [54, 55] and improvements in medial, lateral and patellofemoral unicompartmental KAs [56‐58]. To determine which patients may benefit best from KA surgery in general and typically from these presumed technological improvements, exploring expectations of activities in more detail seems to be more essential than ever. Recent studies already revealed that psychological factors, such as patient perception, understanding of illness, depression and anxiety, play an important role in recovery and outcome after knee replacement [59]. Even without taking into account these psychological factors in this study, we now have shown that younger patients expect to perform many different activities after KA. To improve patient satisfaction, we recommend further studies to investigate how to fulfil all these different expectations and to explore what effects these activities have on survivorship of knee implants.

Concerning the choice for a PROM, previous studies showed importance of choosing an outcome measure in which all desired levels of performance could be measured. This implicates that a PROM should not have a considerable ceiling or floor effect [60]. Additionally, we learned from our study that to determine whether a KA is meeting expectations in younger patients, it is crucial to take into account participation in activities of more than only daily life activities. Following the similar motivation for surgery between daily life, work and leisure time activities of the PROMs on a group level and also regarding the outcomes of the focus groups, we are of the opinion that PROMs should address work and leisure time activities in addition to only daily life activities. Moreover, to reflect the personal goals and needs of the patient, preferably these PROMS should be more individualized.

The average PROM scores did not differ much, but the number and types of activities incorporated in the PROMs are highly variable (Table 6). To avoid worldwide creation of even more and larger PROMs, including every possible important activity for younger patients, we suggest choosing a PROM in which incorporated activities can be individualized, like the SQUASH [43] or the New KSS for leisure time activities [35, 36]. Adding weight factors to the incorporated activities might be considered in order to meet patient’s expectation, personal goals and needs even more.

According to the results of our survey, the New KSS scored highest in importance with regard to its activities. Its query of both high-demand activities and three priority activities has already been pointed out as unique in the recent systematic review considering PROMs after TKA [61]. Nakahara et al. [62] also investigated expectations and satisfaction regarding daily life activities of the New KSS. Comparable with the importance scores of our survey, they concluded that daily life activities associated with ‘walking’, ‘climbing up or down stairs’ and ‘getting into and out of a car’, had great impact on meeting expectations and patient satisfaction. Besides the possibility to incorporate activities of individual importance, the New KSS consists of objective surgeon-reported components and patient-reported components regarding expectations and satisfaction as well, making it altogether a committed clinical outcome measure to evaluate younger patients after KA [35, 36]. The Dutch SQUASH is another questionnaire, which can be highly individualized. It contains open questions on habitual activities with respect to daily life, work and leisure time, as well as incorporated standard activities, which are highly valued in our survey [43]. As the SQUASH is especially designed to score physical activities in an adult population and is reproducible, valid and shorter than the New KSS, this questionnaire could also be a useful alternative to quantify activity level. The OKS-APQ seems to be a valuable PROM for younger KA patients as well, as it consists of only eight extra items in addition to the OKS [37]. Those items are four extra—highly valued—activities and four items concerning performance and awareness, such as timing and adjustments of activities, which were also mentioned in our focus groups (Table 2). The WORQ, which was developed to assess physical difficulties in work and is a reliable, valid and responsive questionnaire [33], turned out to consist of activities of importance to younger OA patients and might be used in addition to PROMs, which do not include work-related activities.

A strength of our study is the qualitative nature, as the most appropriate way to collect data to support content validity that adequately reflects the patient perspective. There are no a priori sample size estimations in qualitative research; however, most projects reach data saturation after conducting between four and six focus groups [38, 63]. Also in our study, after four focus groups we could formulate the 16 main activity categories for daily life, work and leisure time. We performed another two focus groups in which no new main activities could be extracted, after which we concluded that data saturation was reached. A consequence of using focus group methodology, however, is that activities reported may be listed only once by 1 of 37 patients. So, by this study, we are not able to quantify importance of all the different activities mentioned. Furthermore, this study is not able to answer the question what activities are important for what type of patients, according to sex, ASA classification or work type. Another strength is that in the survey, patients scored importance of incorporated activities out of some popular and new PROMs. Besides rating importance, by modifying the Knee Activity Score of Weiss et al. [45] and taking into account frequency of performance and bother regarding the activity, we assessed relevance of activities in terms of ‘motivation for surgery’. Lastly, we calculated final outcome scores of the PROMs, with regard to their incorporated activities. A limitation of our study is that the study sample of participants was based on the focus group methodology of data saturation. A study sample of 37 patients was enough to reach data saturation for the focus group study, but this number of participants was probably too small to find clinically relevant outcomes for the additional survey. Because of the relatively small number to perform quantitative analyses, we decided not to statistically test differences of the survey results. So, to assess whether these survey results are representative for the total group of younger KA patients, a population-based study should be performed. Although the studied patient group is small, the participating patients consist of both sexes (n = 22 males and n = 15 females), and they are working in all areas of the ISCO-08 and participating in a fair amount of different sports, including both low-, intermediate- and high-impact types (Table 1). Thereby, we avoided selection bias in the activities mentioned in the focus groups, and by this diversity, we can still feel comfortable with our results. A second limitation is that seven PROMs were assessed out of 47 currently available knee-scoring systems to assess the success of KA [61]. However, evaluating activities from all existing PROMs seemed not manageable, so we selected the activities in recommended PROMs of the Dutch Orthopaedic Association (NOV) and new PROMs, especially addressing activities for younger patients. From these seven PROMS, we already extracted 72 activities, which took about 30 min time of our patients to score, after the time span of the focus group of approximately one hour. Moreover, one should bear in mind that our summarized PROM score is dependent on the number of activities, as not every PROM incorporates the same amount of activities. Nevertheless, this survey aimed to obtain a first insight whether the assessed activities of daily living, work and leisure time from these PROMs are of value to use for both clinical decision-making and future research concerning activities in this younger group of knee OA patients awaiting KA, in order to increase their satisfaction.

In conclusion, orthopaedic surgeons should realize that younger OA patients have many different expectations of activities of daily life, work and leisure time to perform better after KA. Expectations of leisure time activities varied the most in expected forms, circumstances and intensity and often patients expected activities of ‘low-impact’ to be practiced at more challenging levels. Activities of daily life, work and leisure time from PROMs are valued as similar important according to motivation for surgery. All seven evaluated PROMs score activities, which were rated as important to younger OA patients, but not one PROM covers all activities rated as important. For evaluation of the clinical outcomes of younger KA patients, we suggest choosing knee PROMs that can be individualized and evaluate more than only activities of daily life, including activities of work and leisure time.