summary Hip Osteoarthritis is degenerative disease of the hip joint that causes progressive loss of articular cartilage of the femoral head and acetabulum. Diagnosis can be made with plain radiographs of the hip. Treatment is observation, NSAIDs, and corticosteroids for minimally symptomatic patients. Hip arthroplasty is indicated for progressive symptoms with severe degenerative disease. Epidemiology Incidence hip OA (symptomatic) 88 per 100,000 per year knee OA (symptomatic) 240 per 100,000 per year Risk factors modifiable articular trauma muscle weakness heavy physical stress at work high impact sporting activities non-modifiable gender login to view 1 more bullet increased age genetics developmental or acquired deformities login to view 3 more bullets Etiology Pathophysiology pathoanatomy articular cartilage changes with osteoarthritis login to view 6 more bullets synovium and capsule change with osteoarthritis login to view 11 more bullets Cell biology proteolytic enzymes matrix metalloproteases (MMPs) login to view 5 more bullets tissue inhibitors of MMPS (TIMPs) control MMP activity preventing excessive degradation imbalance between MMPs and TIMPs has been demonstrated in OA tissues inflammatory cytokines secreted by synoviocytes and increase MMP synthesis login to view 4 more bullets Genetics inheritance non-mendilian genes potentially linked to OA vitamin D receptor estrogen receptor 1 inflammatory cytokines login to view 5 more bullets Other factors rapidly progressive osteoarthritis (RPOA) drug toxicity login to view 2 more bullets cytokine-mediated immunological mechanisms autoimmune reactions inciting subchondral insufficiency fractures Classification Tonnis Classification Grade 0 Normal radiographs Grade 1 Sclerosis of femoral head and acetabulum Slight joint space narrowing Slight lipping at joint margins Grade 2 Small cysts in femoral head/acetabulum Moderate joint space narrowing Moderate loss of head sphericity Grade 3 Large cysts in femoral head/acetabulum Joint space obliteration/severe narrowing Severe femoral head deformity vs. AVN Presentation History identify age, functional activity, pattern of arthritic involvement, overall health and duration of symptoms Symptoms function-limiting hip pain effect on walking distances pain most commonly localized to groin region, but also commonly be referred to lateral hip, anterior knee, thigh, buttock, or low back pain at night or rest hip stiffness mechanical instability, locking, catching sensation Physical exam inspection body habitus gait leg length discrepancy skin (e.g. scars) range of motion lack of full extension (>5 degrees flexion contracture) lack of full flexion (flexion < 90-100 degrees) limited internal rotation Neurovascular exam straight leg test negative Imaging Radiographs recommended views standing AP pelvis AP + lateral hip optional views false profile view (e.g. hip dysplasia) findings osteoarthritis login to view 4 more bullets pelvic obliquity login to view 2 more bullets acetabular retroversion login to view 1 more bullet Studies Histology loss of superficial chondrocytes replication and breakdown of the tidemark fissuring cartilage destruction with eburnation of subchondral bone Treatment Nonoperative NSAIDs indications login to view 1 more bullet technique login to view 1 more bullet walking stick decreases the joint reaction force on the affected hip when used in the contralateral upper extremity weight loss, activity modification and exercise program/physical therapy indications login to view 2 more bullets technique login to view 1 more bullet corticosteroid joint injections indications login to view 2 more bullets controversial treatments acupuncture viscoelastic joint injections glucosamine and chondroitin recommendation against use prescription opioids including tramadol intra-articular hyaluronic acid injections Operative arthroscopic debridement indications login to view 2 more bullets not recommended for Tönnis grade 2 radiographic arthrosis login to view 1 more bullet periacetabular osteotomy +/- femoral osteotomy indications login to view 1 more bullet outcomes login to view 2 more bullets femoral head resection indications login to view 2 more bullets hip resurfacing indications login to view 2 more bullets total hip arthroplasty (THA) indications login to view 3 more bullets