Osteoarthritis

Osteoarthritis Description Characterised by pathologic changes in the joints (cartilage, bone and synovium) and periarticular structures (ligaments, tendon, muscle and periarticular fat) Epidemiology Most common form of arthritis 7% of the population has it More common in women than men Due to hormones, post-menopause, high BMD Most common cause of disability in adults Prevalence increases with age More than 80% of people aged more than 75 are radiologically affected 44% are asymptomatic Rare in people under 30 Risk factors Genetics 50% risk of hip or knee Biomechanics Occupation Obesity Trauma Sport Muscle bulk Position sense Causes Primary Secondary Joint trauma Causes cartilage injury or joint instability such as ACL rupture or ankle fracture Cartilage removal Hereditary E.g. meniscectomy More likely to present with 3 or more Connective tissue conditions that lead to chronic joint instability joint E.g. Ehlers-Danlos syndrome Congenital dysplasia of the hips Inflammatory arthritis E.g. RA, calcium pyrophosphate deposition Joint infections Locations Can involve any joint Usually affects proximal hands – small joints PIP DIP Most commonly involved joint of the hand 1 st CMC Weight bearing joints Knees Overall most common Hips Feet Facet joints of the cervical and lumbar spine Associated with creaking/clicking and cool joint swelling Disease course Unpredictable May be slow and progressive May stabilise overtime Pathogenesis Age Impaired chondrocyte function Cumulative trauma Strength and position sense Not just non-inflammatory wear and tear May also have local and systemic inflammation Inflammation to wear particles Unlike RA the inflammation in OA is not the main driver of disease process Secondary process secondary process induced by cartilage damage Clinical features May have insidious or acute onset Presents with symmetrical arthritis Pain Not due to the loss of articular cartilage because cartilage does not have neural or vascular structures Due to a range of intra-articular and periarticular sources of nociception that due to: Synovitis Subchondral bone changes Periosteum disruption associated with osteophyte formation Microfractures Ligament degeneration Capsular distension -> due to effusion Muscle spams Nerve compression Bone remodelling, osteophyte formation, weakening of periarticular muscles Ligament laxity If pain is chronic Central sensitisation -> alters pain experience Sensitisation is independent of radiographic severity or symptom duration Related to synovitis and effusion Crepitus and creaing from the joints Short duration stiffness after activity and early morning Less than 30 minutes Decreased range of motion Joint effusion If present -> cool to touch Heberden’s nodes Affects distal IP joints Bouchard’s nodes Affects proximal IP joints If first metatrasopharnygeal joint Hallux valgus Knee malignment Knee baker’s cysts Symptoms worsen with physical activity Things to identify on physical examination Specific joints involved Presence of inflammation – swelling Degree of joint disruption Associated muscle weakness Crepitus and cool effusion Investigations Labs Not required for diagnosis Inflammatory markers are usually normal Radiological findings Should not be used for diagnosis because the poorly correlate with symptoms and do not change management Not required for patients with typical clinical presentation and do not have red flag features Asymmetric loss of joint space Subchondral sclerosis Osteophytes Cracks Bone cysts Joint aspiration/arthrocentesis For patients with joint swelling Useful for excluding other causes such as gout Synovial fluid characteristics Straw yellow colour Transparent High viscosity WBC of 200 to 2000 Neutrophils less than 25% Management Goals: Pain management Maintain and optimise physical function Maintain and optimise ability to perform daily activities Minimise associated disability Prevent complications Maximise health related quality of life Lifestyle Physical activity Functional exercise Regular aerobic physical activity Weight loss Psychological therapies CBT Thermotherapy Heat or cold application May reduce pain Glucosamine with chondroitin Mixed evidence Most guidelines recommended against due to a lack of proven results Topical NSAIDs E.g. diclofenac Small benefit compared to placebo Topics are preferred to oral for hand OA and is first line Oral paracetamol and NSAIDs NSAIDs preferred over paracetamol regardless of pain location Use should be limited in elderly, and people with RF for GI, kidney or heart toxicity. Stop if there is no benefit E.g. celecoxib or ibuprofen Intra-articular injections Corticosteroid injection Short term relief in patients with knee or hip OA Intraarticular hyaluronan Duloxetine Reduces pain and improves physical function Opioids Limited role Can be considered for patients with severe persisting functional impairment If used -> short term only Not recommended for OA of the hand E.g. tapentadol safter than oxycodone Surgical management For patients with severe persisting functional impairment or pain despite maximum non-surgical management Options for hips ad knee Osteotomy Joint replacement Arthroplasty Arthroscopic lavage or debridement are not recommended Meniscectomy is not recommended for degenerative meniscal tears Complementary medicines Lack of evidence to support the use of fish oil, krill oil,, glucosamine, chondroitin and tumperin for pain relief and symptom improvement Complications Deterioration in quality of life Reduced mobility Chronic stiffness Muscle weakness Increased fall risk Mental health Depression and anxiety