Joint pathology Notes

NOTES NOTES JOINT PATHOLOGY GENERALLY, WHAT IS IT? PATHOLOGY & CAUSES ▪ Disorders affecting joints ▪ Most commonly caused by trauma SIGNS & SYMPTOMS ▪ Asymptomatic or pain during rest/ movement DIAGNOSIS DIAGNOSTIC IMAGING ▪ Radiography ▪ MRI LAB RESULTS ▪ Synovial fluid analysis TREATMENT ▪ Treat symptoms pharmacologically ▪ Surgical procedures BAKER'S CYST osms.it/bakers-cyst PATHOLOGY & CAUSES ▪ Synovial fluid accumulates in popliteal bursa (between medial head of gastrocnemius, semimembranosus muscles) → swelling ▪ Adults: popliteal bursa communicates with synovial sac; underlying knee joint disease main cause ▫ Knee joint disease → ↑ synovial fluid production → synovial fluid squeezes through valve-like formation into bursa → fluid unable to flow backward → bursa enlarges → lump-like structure in the popliteal fossa ▪ Children: noncommunicating cyst; usually arises as primary process 658 OSMOSIS.ORG CAUSES ▪ ▪ ▪ ▪ Chronic knee joint trauma Osteoarthritis Rheumatoid arthritis Meniscal tears COMPLICATIONS ▪ Cyst enlargement ▫ In popliteal space → obstruction of veins → lower leg swelling ▫ Extension to calf → swelling, redness, bruising, positive Homan’s sign (calf pain during dorsiflexion of the foot) → similar to deep-vein blood clot ▪ Rupture

Chapter 114 Joint Pathology DIAGNOSIS SIGNS & SYMPTOMS ▪ May be asymptomatic ▪ Stiffness and pain in the knee → worse with prolonged standing DIAGNOSTIC IMAGING Ultrasound and MRI ▪ Fluid-filled cyst; differentiation between cyst, blood clot X-ray ▪ Bone, joint pathology associated with cyst OTHER DIAGNOSTICS ▪ Physical examination ▫ Lump in the back of the knee TREATMENT SURGERY ▪ Surgical excision OTHER INTERVENTIONS Figure 114.1 An MRI scan of the knee joint in the sagittal plane demonstrating a Baker’s cyst in the popliteal fossa. ▪ Fluid aspiration, glucocorticoid intraarticular injection → ↓ size and inflammation ▪ Treat complications ▫ Leg elevation, resting, analgesics BURSITIS osms.it/bursitis PATHOLOGY & CAUSES ▪ Inflammation of bursa (small sac located between muscles, tendons, bone structures) ▪ Inflammation of bursa → ↑ production of synovial fluid → enlargement of bursa → ↑ friction during movement → symptomatology ▪ Most commonly affected bursas ▫ Subacromial, olecranon, trochanteric, prepatellar, infrapatellar CAUSES ▪ Autoimmune disorders ▫ Rheumatoid arthritis, ankylosing spondylitis, scleroderma, systemic lupus erythematosus → chronic course ▪ Overuse/trauma, gout, bacterial infections (septic bursitis) → acute course OSMOSIS.ORG 659

SIGNS & SYMPTOMS ▪ Joint pain; stiffness of joints; surrounding skin red ▪ Acute bursitis ▫ Tenderness, pain during activation of muscles adjacent to inflamed bursa ▪ Chronic bursitis ▫ Swelling with minimal pain Figure 114.3 An MRI scan of the elbow demonstrating a high signal fluid collection in the olecranon bursa in an individual with olecranon bursitis. Figure 114.2 An individual with olecranon bursitis. DIAGNOSIS DIAGNOSTIC IMAGING Ultrasound ▪ Differentiation from Baker’s cyst LAB RESULTS ▪ Aspiration and analysis of synovial fluid ▫ Infection: ↑ polymorphonuclear leukocytes, proteins, ↓ glucose ▫ Gout: ↑ monosodium urate crystals 660 OSMOSIS.ORG TREATMENT MEDICATION ▪ Non-steroidal inflammatory drugs (NSAIDs) ▪ Injection of steroids, local anesthetics ▪ Septic bursitis ▫ Antibiotics SURGERY ▪ Surgical excision ▫ Chronic or recurrent bursitis OTHER INTERVENTIONS ▪ Resting, elevation

Chapter 114 Joint Pathology OSTEOARTHRITIS osms.it/osteoarthritis PATHOLOGY & CAUSES ▪ Progressive loss of articular cartilage, underlying bone of synovial joints ▪ Articular cartilage damage → chondrocytes replace type II collagen with type I, ↓ proteoglycans → eventual exhaustion, apoptosis of chondrocytes → ↓ elasticity, ↑ cartilage breakdown → clefts in articular surface (fibrillations), “joint mice” in synovial space with inflammation of synovium → bone exposition → rubbing other bone → eburnation (polished ivory look) ▪ Due to damage/inflammation, new bone formation on edges of bone with outward growth → osteophyte (enlargement of the joint with a knob-like look) ▫ Bouchard nodes: proximal interphalangeal finger joints affected ▫ Heberden nodes: distal interphalangeal finger joints affected ▪ Most commonly affected joints ▫ Lower spine, hip, knee, foot and hand joints CLASSIFICATION ▪ Primary ▫ Usually idiopathic ▪ Secondary ▫ Caused by some other condition (e.g. diabetes, alkaptonuria, hemochromatosis, chronic joint injury) anabolism of cartilage ▪ Obesity ▫ Excessive load, metabolic disorders affect joints ▪ Genetic disorders ▫ Mutations in cartilage building collagens (types II, IX and XI) ▪ Biological sex ▫ Biologically female more prone ▪ Previous joint injuries ▪ Infection ▪ Neurologic disorders COMPLICATIONS ▪ Cystic degeneration of subchondral bone ▪ Surrounding ligaments, neuromuscular abnormalities SIGNS & SYMPTOMS ▪ Sharp pain/burning sensation worsened by prolonged activity ▪ Limited range of motion ▪ Morning stiffness > one hour ▪ No swelling RISK FACTORS ▪ Aging ▫ Cartilage thinning with ↓ hydratation → protein accumulation, collagen crosslinking → cartilage is more breakable; ↑ calcification of meniscus, cartilage ▪ Inflammation → ↑ proinflammatory cytokines ▫ IL1, IL6, TNF → ↑catabolism/↓ Figure 114.4 Heberden’s node on the distal interphalangeal joint of the right index finger in an individual with osteoarthritis. OSMOSIS.ORG 661

DIAGNOSIS DIAGNOSTIC IMAGING Radiography ▪ Loss of joint space ▪ Subchondral bone sclerosis MRI ▪ Loss of joint space ▪ Subchondral bone sclerosis ▪ Osteophytes ▪ Visualisation of articular cartilage, surrounding soft tissues CT scan ▪ Displacement of foot, ankle, patellofemoral joint Bone scan ▪ Detect abnormalities LAB RESULTS ▪ Arthrocentesis Figure 114.5 An X-ray image of the pelvis demonstrating osteoarthritis of the right hip joint. The femoral head is malformed, there is marked loss of joint space and there are numerous subchondral bone cysts. 662 OSMOSIS.ORG TREATMENT MEDICATIONS ▪ Pain management ▫ Acetaminophen, tramadol, topical and oral non-steroidal anti-inflammatory drugs (NSAIDs) ▪ Intra-articular injections ▫ Corticosteroids ▫ Sodium hyaluronate SURGERY ▪ Osteotomy ▫ Individuals < 60 years with malalignment of hip, knee joint ▪ Arthroplasty ▪ Stem-cell therapy OTHER INTERVENTIONS ▪ ▪ ▪ ▪ Exercise Weight loss Physical therapy Electromagnetic field stimulation for individuals with knee osteoarthritis

Chapter 114 Joint Pathology SLIPPED CAPITAL FEMORAL EPIPHYSIS osms.it/slipped-capital-femoral-epiphysis PATHOLOGY & CAUSES ▪ Anterior displacement of femoral head metaphysis, with epiphysis remaining in hip acetabulum ▪ Caused by growth plate (physis) fracture ▪ Example of type I Salter–Harris fracture usually affecting one hip ▪ Hypertrophy of growth plate → abnormal endochondral ossification, cartilage maturation → growth plate weakness → if too much force generated across growth plate → slippage COMPLICATIONS ▪ Osteoarthritis ▪ Metaphysis slippage → ↓ blood flow → avascular necrosis ▪ Secondary SCFP affecting other hip; usually within a year of first SCFP ▪ Unstable displacement: ↑ complication rate SIGNS & SYMPTOMS ▪ Hip, groin, knee pain ▪ Duck-like gait ▪ Hip in external rotation, flexion CLASSIFICATION ▪ Based on disease course ▫ Acute: > three weeks ▫ Chronic: < three weeks ▫ Acute on chronic: chronic with acute exacerbations ▪ Based on lesion stability ▫ Stable: walking possible with/without crutches ▫ Unstable: walking impossible, even with crutches ▪ Displacement of the femoral head from neck; seen on radiography ▫ Type I: slippage < 33% ▫ Type II: 33–50% ▫ Type III: > 50% RISK FACTORS ▪ ▪ ▪ ▪ ▪ Obesity ↓ thyroid, growth hormone Osteodystrophy Down syndrome Demographics ▫ Adolescent black males of African descent most commonly affected Figure 114.6 An X-ray image of the pelvis demonstrating a slipped capital femoral epiphysis on the left side. OSMOSIS.ORG 663

DIAGNOSIS DIAGNOSTIC IMAGING X-ray ▪ Anteroposterior X-ray ▫ Melting ice cream cone appearance visible through line of Klein (virtual line parallel to femoral neck’s upper edge) ▪ Frog-leg X-ray ▫ Straight line through center of femoral neck anterior to epiphysis (rather than central) TREATMENT SURGERY ▪ Fixation with a cannulated screw ▪ Preventive fixation of the other hip ▫ Children with SCFP before the age of 10 ▫ Persons with endocrinopathies ▪ Osteotomy MRI, CT scan ▪ Accurate measurements of displacement degree TRANSIENT SYNOVITIS osms.it/transient-synovitis PATHOLOGY & CAUSES ▪ Inflammation of hip joint synovial membrane ▪ Cause relatively unknown, but may be preceded by upper respiratory tract infection ▪ Most commonly seen in male children 3–10 years ▪ Most commonly limited to one side SIGNS & SYMPTOMS ▪ ▪ ▪ ▪ May be asymptomatic Tenderness/pain during passive movement One-sided pain in the hip, groin, thigh, knee Antalgic limping DIAGNOSIS ▪ Diagnosis of exclusion DIAGNOSTIC IMAGING Ultrasound ▪ Fluids in joint capsule LAB RESULTS ▪ ▪ ▪ ▪ Slightly ↑ white blood cell count ↑ Erythrocyte sedimentation rate ↑ C-reactive protein Needle aspiration ▫ Differentiation between transient synovitis and septic arthritis OTHER DIAGNOSTICS ▪ Limited abduction and internal rotation TREATMENT MEDICATIONS ▪ NSAIDs OTHER INTERVENTIONS ▪ Massage ▪ Rest 664 OSMOSIS.ORG