Ans: B (Osteoarthritis) Ref: Campbell's Operative Orthopaedics, 11th editionExpfanation:Knee OsteoarthritisSymptomso Paino Swelling (due to Joint effusion)o Stiffnesso Crepitus with range of motiono Large osteophytes as palpable swellings (in later stages).Osteoarthritis of the knee first start in the pateliofemoral joint.Isolated Pateliofemoral Arthritiso Cause anterior knee pain that worsens with stair climbingo Pain when rising from a seated position,o Pain not present with walking or running on level surfaces,o Forces on the patella range from between one third and one half of a person's body weight during walking to three times body weight during stair climbing and up to seven times body weight during squatting. Hence extreme flexion causes pain in pateliofemoral osteoarthritisCardinal Features of Osteoarthritiso Progressive cartilage destruction c Subarticular cyst formationo Sclerosis of the surrounding boneo Osteophyte formationo Capsular fibrosis.Symptomso Paino Stiffnesso Swellingo Deformityo Loss of functiono Limpo Difficulty' in climbing stairso Restriction of walking distanceo Progressive inability to perform everyday tasks.Signso Joint swellingo Deformityo Local tendernesso Crepituso Instability* Imagingo X-ray is usually diagnostic.o Shows asymmetrical loss of cartilage (narrowing of the 'joint space'),o Sclerosis of the subchondral bone under the area of cartilage loss.o Cysfs close to the articular surface,o Osteophytes at the margins of the joint.