White Paper: PROMs in Osteoarthritis of the Knee

Healthcare is changing. And it is not only a pandemic that prompted such a shift, the use of more patient-centred oriented tools and digitalisation of clinical systems is rapidly growing.

Orthopedics is a broad clinical landscape and the use of PROMs in this field is one of the most established, all the while the continued research and incorporation of PROMs is evolving at a high pace. Moreover, this is spurred by the promising potential to better understand orthopedic treatment within the patient care pathway long-term.

Due to the sheer vastness of the medical terrain, the following white paper focuses specifically on osteoarthritis of the knee. Osteoarthritis most commonly affects the joints in the knees, hands, feet, and spine and is relatively common in shoulder and hip joints.¹ Moreover, it is the single most frequent cause of disability in older adults with patient’s range of motion and mobility of the joint being adversely affected.^{2, 3}

Here, a  multitude of PROMs exist, be it the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS) among others. Considering the progressively debilitating nature of the condition, clinicians should select PROMs that are able to capture the course of the disease, from the early to more advanced stages to best refine patients’ treatment needs.⁴

There is recognition that PROMs aid the optimal management of therapeutic approaches to alleviate patients‘ symptoms, matching patient expectations and have proven useful in monitoring various treatment effectiveness amongst patients be it therapeutics, physiotherapy or surgery.^{4 – 7}

Siljander et al.,  analyzed PROMs-related publications in total joint arthroplasty from 4 major orthopedic journals (2004 – 2016). Of the 7 prominent PROMs identified most often WOMAC, OKS, and KOOS were those relating to the knee of which OKS and KOOS were most commonly used in Europe.⁸

However, just because a PROM is used frequently in published studies does not necessarily ensure its quality especially when considering its associated psychometric properties.⁹ And so new literature is constantly emerging tempering PROMs for optimum clinical learnings.

The most suitable PROM to implement is very specific as to what the physician and patient want to achieve with such a tool. For example, if a physician wishes to assess pain, stiffness and function of the knee in elderly osteoarthritis patients in the short-term one may opt for the WOMAC score.¹⁰ However, if a long-term overview of disease progression or regression is desired, the KOOS score would be more appropriate as the WOMAC score can also be derived from its dimensions.^{11, 12}

Factors, such as which therapeutic procedures patients are undergoing, questionnaire length, practicability and what derived information from a PROM can be deemed useful are paramount when sifting through a multitude of potential PROs. Ultimately, there is no “correct” PROM to include in patient care for knee osteoarthritis, and a plethora of diversity is observed in the use of PROMs within the surgical and nonsurgical settings.¹³

As PROMs integration continues to develop, every new study facilitates universal learning for all members involved in healthcare infrastructure. A variety of publications exist: those that use PROMs as an endpoint in clinical care in knee osteoarthritis treatment and those that incorporate PROMs for a more holistic approach to treatment and rehabilitation of patients with osteoarthritis of the knee.

For example, in total knee arthroplasty (a common surgical procedure for advanced knee osteoarthritis), Baker et al. used the British joint registry and demonstrated that the use of the implant of a particular manufacturer significantly improved OKS results. While use of a PROM to confirm success of the surgical intervention post-operatively and determine which implantable device yields best results.¹⁴ It does not act as a companion throughout the entire patient journey from the start of the disease manifestation.

Efforts to use PROMs in the assessment of what worked best for patients and how to tailor osteoarthritis physiotherapy exercises specifically to them to enhance their progress and motivation throughout their physiotherapy regime demonstrates that a PROM can be used for more than a therapy endpoint.⁶

The concept of PROMs in itself is rather known, what is unique is how best to make such information available and actionable in a secure manner. PROMs continue to and will assist in treatment, rehabilitation and research in osteoarthritis of the knee if the processes and tools/platforms are optimized correctly. The challenge is to identify a process to manage this growing area that is open, connected and flexible to accommodate data uptake and coherent output. 

Therefore, all future tools will have to be measured against their ability to enhance the reality of everyday clinical routines. Merging the physicians’ knowledge of PROMs with an actionable and supportive digital infrastructure will allow care teams to sustainably change individual treatment experience and systemic healthcare outcomes.