Osteoarthritis (OA), a slowly progressive, degenerative disease of the joints involving their cartilages and surrounding tissues, is highly prevalent throughout the world. It is a leading cause of disability in later stages of the lives of people, having a significant negative impact on the physical and mental health of older adults worldwide. [1,2]. The most commonly affected joints are the knees, hips, hands, facet joints, and feet, but OA knee constitutes 83% of the total OA burden and often results in significant disability.[2,3].The global prevalence of OA knee was found to be 16% for individuals over 15 years of age and increased to 22.9% in individuals aged over 40 years. In 2020, there were 654.1 million individuals with OA knee worldwide. [4]. This condition is more common in females than males, with a ratio between 1.5:1 and 4:1[1,2]. The prevalence of this degenerative pathology not only increased with age and Body Mass Index(BMI) but was also found to be associated with ethnicity, genotype, joint injury and high bone mineral density.[1,2].This debilitating knee pathology is likely to afflict more and more individuals worldwide due to rapid ageing of the global population, rising average body weight and increasing sedentary lifestyle [1,5]. The recent global incidence of OA knee was estimated to be 203 per 10,000 person-years. [4].
In India, osteoarthritis per se is common, affecting 22–39% of the population as per prevalence estimated in the first decade of the new millennium. As seen globally, OA knee is among the commonest disabling joint diseases in India also, and was estimated by a multi-centric Indian study to be ranging between 19% among < 50 years old up to 54.1% among 70 years plus population [6]. Another study compiled the prevalence of OA knee from multiple small studies and reported that the condition of OA knee varied widely across regions of India. [7]. In India also OA knee was higher among older women (51%) than their age-matched male counterparts (33.09%) and the rates were higher in the urban population and people with low physical activity [8].
Symptoms of OA knee include pain that worsens with use and improves with rest; and stiffness that improves after activity. On physical examination, crepitus, swelling, and deformity may be present. [9]. OA knee is diagnosed based on clinical and radiological examination that may include X-ray, CT-scan and MRI. Based on radiological findings, OA knee can be graded using Kellgren Lawrence system into four grades. [10]
OA knee can be treated conservatively or surgically [11]. Total Knee Replacement (TKR) is considered to be one of the most common and reliable treatments for OA knee, which mainly involves removing the diseased and normal femoral condyles, tibial plateau and the patella and cementing a prosthesis (which are of different types) in position. (11, 12). TKR is indicated when there is radiological confirmation of the disease associated with worsening of symptoms despite conservative treatment. [14]. TKR is also done to correct significant or progressive deformity of the knee in patients with OA [15][16]. The health outcomes of the TKR are measured through various patient-reported outcome measures (PROMs). Most commonly used PROMs for measuring post-TKR changes in the knee are The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), The Oxford Knee Score (OKS), The New Knee Society Score (KSS) and The Knee Injury and Osteoarthritis Outcome Score (KOOS).
Although the prevalence and the incidence of OA knee varies between countries, the burden of OA is increasing in most countries and therefore presents a major public health challenge, especially since, the global population is ageing rapidly in every region of the world[5]. The number of TKRs being done to mitigate the burden of OA knee has also been increasing throughout the world. To put things in perspective, in Australia, by 2030, the incidence of total knee replacement surgeries is estimated to increase by 276%. In the United States, in the year 2010, approximately 700,000 TKA surgeries were performed, and the demand is predicted to grow to 3.8 million per annum by the year 2030.[17,18]. According to Aseer et al, a study from 2017, there has been “an average growth of 30% in TKR procedures each year and the growth rate is expected to surge in the forthcoming decade” [19].
It has been found that OA knee has a significant impact on the quality of life (QoL) of the patients.[20] TKR provides significant relief from joint pain and stiffness and enhances joint movement; therefore, it increases individual’s mobility which in turn improves Quality of Life (QoL) of people undergoing the procedure, albeit the magnitude of improvement varies between individual’s characteristics and settings [12,19]. Therefore, TKR is inducted in clinical guidelines of many countries and suggested by professional bodies as treatment of choice for OA knee of certain severity. [21]
Public policymaking process is meant to weigh the cost and consequences of any medical intervention, because only the most cost-effective procedures are to be recommended, which leads to carrying-out of cost-utility studies of interventions. For the same reasons, a cost-utility study to estimate the cost-effectiveness of TKR in India was planned, for which costing data from provider’s end is available in the country, but relevant clinical effectiveness estimates are not readily available in the extant literature that can guide our proposed cost-utility study. For example, the clinical effectiveness of TKR and its various dimensions are being published for many years from various settings; systematic reviews of such individual studies were also published from time to time, however, the existing reviews only estimated effectiveness of TKR in either short or long-term, but none reported the effectiveness over all the possible follow-up periods in a single article. We felt that the effectiveness estimates of TKR over different follow-up periods need systematic synthesis for our main cost-utility study and needs to be presented in one single document, hence, the review was planned. Also, the latest review on this topic was published in 2015 comprising articles that were published up to 2012, therefore, this topic needed to be refreshed with evidence published after 2012, especially with more recent evidences from diverse settings, as TKR is being applied more widely to different populations globally. Moreover, the determinants of the “success” of TKR were yet to be reviewed systematically from the existing body of evidence, inclusion of which may add substantial value to the current review process.
Therefore, a systematic review of literature was undertaken with the following objectives: to refresh the evidence of clinical effectiveness of TKR with recent results, to explore the effectiveness of TKR for the entire possible follow-up period and to explore the determinants influencing its success.