Contributions to the management of osteoarthritis

Osteoarthritis (OA) is a multifactorial joint disease affecting all the tissues of the joint. Knee, hand and hip joints are frequently involved. OA is a serious health problem because it entails a high clinical burden of pain and disability resulting in a reduced quality of life. Moreover, the prevalence of OA is high and rising. Especially in developed countries, this leads to a growing impact on health care. No cure is available and treatment focuses primarily on the reduction of symptoms as pain and loss of function. Treatments encompass nonsurgical modalities (education, exercise, analgesics, life style advices) and surgical modalities (such as total joint replacement (TJR)). Several international recommendations emphasize the importance and efficacy of starting with nonsurgical treatment modalities, before considering surgical treatment modalities. Nevertheless, nonsurgical treatment modalities are insufficiently utilized, and the number of surgeries is rising substantially. TJR is considered an effective treatment, but up to 30% of patients are dissatisfied after total knee replacement. Therefore, there is a clear need to improve the management of OA. The aim of this thesis is to contribute to the non-surgical management of established knee and hip OA by 1) identifying appropriate outcome measures, 2) identifying risk factors, and 3) establishing evidence of low dose radiation therapy. Identifying appropriate outcome measures We evaluated the responsiveness (i.e. the ability to detect changes over time) of four widely used patient reported outcome measures (PROMs) and concluded that the WOMAC-PF is able to detect changes over time in physical function in patients with knee OA receiving standardized non-surgical treatment. Furthermore, we estimated the patient acceptable symptom state (PASS) values and determined that these values in patients with clinical knee OA are robust across different PROMs assessing physical function. Identification of risk factors We described the development and validation of criteria for clinical worsening in knee and hip OA using a literature, expert opinion and data driven approach. We identified a set of criteria showing an acceptable combination of sensitivity and specificity. Moreover, short-term clinical worsening turned out to be a clear independent risk factor for worsening at 2 years in established knee and hip OA. Establishing evidence of low-dose radiation therapy After systematically reviewing the literature we concluded that there is currently insufficient high-level evidence available to indisputably demonstrate the effectiveness on pain and functioning of low-dose radiation therapy (LDRT) in OA patients. Therefore, we conducted a randomized, double-blinded, sham-controlled trial to evaluate the effectiveness of LDRT on symptoms. The results showed that LDRT does not lead to a substantial reduction of symptoms. Therefore, we advise against the use of LDRT as treatment for knee OA