There are many types of arthritis: Achilles tendinitis, Achondroplasia, Acromegalic arthropathy, Adhesive capsulitis, Adult onset Still's disease, Amyloidosis, Ankylosing spondylitis, Anserine bursitis, Avascular necrosis, Behcet's syndrome, Bicipital tendinitis, Blount's disease, Brucellar spondylitis, Bursitis, Calcaneal bursitis, Calcium pyrophosphate dihydrate (CPPD), crystal deposition disease, Caplan's syndrome, Carpal tunnel syndrome, Chondrocalcinosis, Chondromalacia patellae, Chronic synovitis, Chronic recurrent multifocal osteomyelitis, Churg-Strauss syndrome, Cogan's syndrome, Corticosteroid-induced osteoporosis, Costosternal syndrome, CREST syndrome, Cryoglobulinemia, Degenerative joint disease, Dermatomyositis, Diabetic finger sclerosis, Diffuse idiopathic skeletal hyperostosis (DISH), Discitis, Discoid lupus erythematosus, Drug-induced lupus, Duchenne's muscular dystrophy, Dupuytren's contracture, Ehlers-Danlos syndrome, Enteropathic arthritis, Epicondylitis, Erosive inflammatory osteoarthritis, Exercise-induced compartment syndrome, Fabry's disease, Familial Mediterranean fever, Farber's lipogranulomatosis, Felty's syndrome, Fibromyalgia, Fifth's disease, Flat feet, Foreign body synovitis, Freiberg's disease, Fungal arthritis, Gaucher's disease, Giant cell arteritis, Gonococcal arthritis, Goodpasture's syndrome, Gout, Granulomatous arteritis, Hemarthrosis, Hemochromatosis, Henoch-Schonlein purpura, Hepatitis B surface antigen disease, Hip dysplasia, HIV induced inflammatory arthritis, Hurler syndrome, Hypermobility syndrome, Hypersensitvity vasculitis, Hypertrophic osteoarthropathy, Immune complex disease, Impingement syndrome, Jaccoud's arthropathy, Juvenile ankylosing spondylitis, Juvenile dermatomyositis, Juvenile rheumatoid arthritis, Kawasaki disease, Kienbock's disease, Legg-Calve-Perthes disease, Lesch-Nyhan syndrome, Linear scleroderma, Lipoid dermatoarthritis, Lofgren's syndrome, Lyme disease, Malignant synovioma, Marfan's syndrome, Medial plica syndrome, Metastatic carcinomatous arthritis, Mixed connective tissue disease (MCTD), Mixed cryoglobulinemia, Mucopolysaccharidosis, Multicentric reticulohistiocytosis, Multiple epiphyseal dysplasia, Mycoplasmal arthritis, Myofascial pain syndrome, Neonatal lupus, Neuropathic arthropathy, Nodular panniculitis, Ochronosis, Olecranon bursitis, Osgood-Schlatter?s disease, Osteoarthritis, Osteochondromatosis, Osteogenesis imperfecta, Osteomalacia, Osteomyelitis, Osteonecrosis, Osteoporosis, Overlap syndrome, Pachydermoperiostosis, Paget's disease of bone, Palindromic rheumatism, Patellofemoral pain syndrome, Pellegrini-Stieda syndrome, Pigmented villonodular synovitis, Piriformis syndrome, Plantar fasciitis, Polyarteritis nodosa, Polymyalgia rheumatica, Polymyositis, Popliteal cysts, Posterior tibial tendinitis, Pott's disease, Prepatellar bursitis, Prosthetic joint infection, Pseudoxanthoma elasticum, Psoriatic arthritis, Raynaud's phenomenon, Reactive arthritis/Reiter's syndrome, Reflex sympathetic dystrophy syndrome, Relapsing polychondritis, Retrocalcaneal bursitis, Rheumatic fever, Rheumatoid arthritis, Rheumatoid vasculitis, Rotator cuff tendinitis, Sacroiliitis, Salmonella osteomyelitis, Sarcoidosis, Saturnine gout, Scheuermann's osteochondritis, Scleroderma, Septic arthritis, Seronegative arthritis, Shigella arthritis, Shoulder-hand syndrome, Sickle cell arthropathy, Sjogren's syndrome, Slipped capital femoral epiphysis, Spinal stenosis, Spondylolysis, Staphylococcus arthritis, Stickler syndrome, Subacute cutaneous lupus, Sweet's syndrome, Sydenham's chorea, Syphilitic arthritis, Systemic lupus erythematosus (SLE), Takayasu's arteritis, Tarsal tunnel syndrome Tennis elbow, Tietse's syndrome, Transient osteoporosis, Traumatic arthritis, Trochanteric bursitis, Tuberculosis arthritis, Arthritis of Ulcerative colitis, Undifferentiated connective tissue syndrome (UCTS), Urticarial vasculitis, Viral arthritis, Wegener's granulomatosis, Whipple's disease, Wilson's disease and Yersinial arthritis. That's 171 types!