Neuromuscular exercise prior to joint arthroplasty in patients with osteoarthritis of the hip or knee.

INTRODUCTION Osteoarthritis (OA) and the diagnosis OA is a degenerative joint disease which alters the structure of the cartilage. The thickness of the cartilage diminishes and the adjacent structures, i.e. synovial membrane, menisci and underlying bone, are also affected. In time, OA causes pain, lowers physical function and ultimately leads to a reduced quality of life. [2] In OA research, two possibly interacting views govern the field, namely a biomechanical view, where altered loading patterns of the joint are thought to cause additional wear to the cartilage, and a systemic view, where inflammation is the driving factor behind cartilage degeneration. [5-10] For the clinician, however, OA may be better defined by its two cardinal symptoms, i.e. pain and functional loss, or by its pathology such as radiographic changes, Figure 1. OA symptoms Traditionally, a medical history of the patient ́s symptoms, severity and duration is obtained through a semistructured interview (anamnesis) led by a health care professional. Through this, an overall, however possibly subjective, idea of the patient ́s illness is obtained. To facilitate interpretation of the patient ́s response, great focus has been placed on the development of patient self-reported questionnaires over the last two decades. In the clinical setting, symptom severity may be evaluated by disease-specific questionnaires, examples of which include the Oxford Knee Score (OKS) or the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Oxford Hip Score (OHS) or Hip Osteoarthritis Outcome Score (HOOS) for patients with knee or hip OA respectively. Here, the challenge lies in defining cut points for disease severity based on the score derived from the questionnaire. [11] OA pathology In the early stages of the degenerative process, pathological changes are detectable by means of biomarkers; i.e. molecular fragments measured in patient’s plasma. However, biomarkers have not attained a position in the clinical setting to secure diagnosis. In mild OA, the thinning of joint cartilage and its effect on underlying bone may be visualised by magnetic resonance (MR) scanning. This highly detailed modality is appreciated by many clinicians but is costly and time-consuming. More advanced OA can be seen as radiographic features, i.e. osteophytes, joint space narrowing and sclerosis of subchondral bone. The radiological severity of OA may be evaluated through various classification systems. [12-14] Defining severity of the disease is challenging. Generally, joint space narrowing and subchondral sclerosis are accepted as signs of more progressive disease. [15, 16] Throughout the OA literature, the Kellgren & Lawrence method (KL) is most commonly used. Radiographic changes are graded from 1 to 4 with severe joint space narrowing and marked subchondral sclerosis being present in grade 4. [12] As illustrated in Figure 1, the diagnosis of OA is not always straightforward since patients with symptoms of OA may not necessarily display radiographic features of the disease and vice versa. [17-20] The discrepancy often found between symptom and Neuromuscular Exercise prior to Joint Arthroplasty in Patients with Osteoarthritis of the Hip or Knee