Signs & Symptoms

Non-traumatic:

• Infection (osteomyelitis, septic arthritis): rapid onset of redness, pain, swelling, tenderness, systemic symptoms, difficulty in weight-bearing, usually 1 joint
• Tumours: persistent non-mechanical bone pain at night/rest, unexplained localised lump
• Inflammatory arthritis: pain worse at rest/inactivity, joint swelling, warmth, tenderness, morning stiffness >30 mins, occurs in symmetrical synovial joints. There may be a history of psoriasis, IBD, uveitis, episcleritis & scleritis. In children with non-traumatic synovial joint swelling = JIA
• Patellofemoral pain: diffuse ache behind the patella, aggravated by stairs/running/prolonged walking/sitting. Most likely in young active females. Diagnostic test = anterior knee pain on squatting
• Knee OA: localised pain, morning stiffness <30 mins, pain activated by movement, improved with rest
• Referred Pain: Especially in children from the hip (SCFE, septic arthritis of the hip, transient synovitis, Perthes disease, JIA of the hip). In general, think about OA of the hip & lumbar radiculopathy
• Osgood-Schlatter’s Disease: Associated with growth spurts in boys 10-15 years old. Unilateral knee pain exacerbated by knee extension & is gradual in onset. Tender and swollen over the tibial tuberosity
• Bursitis (housemaid’s knee): Anterior knee pain and swelling, especially on pressure and activity. A history of pressure and friction. Pre-patellar bursitis is the most common.
• Gout/Pseudogout: Acute onset, pain, tenderness & swelling. Tophi may be present
• Degenerative Meniscal Tear: Mid-age group, Non-specific gradual increasing knee pain (medial – most involved tear) that is hard to distinguish from OA. There may be catching/locking (esp. with squatting/twisting) & loss of full flexion. Palpable/audible clicking.
• Baker’s Cyst: Popliteal swelling (firm on extension & soft on flexion) with swelling + stiffness on the posterior aspect of the knee. Can rupture → Calf pain/swelling + discolouration (DVT Differential Dx).
• Patellar Tendinitis: Athletes involved in sports that include jumping. Common in teenage boys during a growth spurt. Anterior knee pain aggr. by activity & pain reproduced by resisted knee extension.
• Osteochondritis Dissecans: Common issue, idiopathic, in growing adolescents. w/ vague pain worse w/ exercise. There may be locking/catching/giving way. Offer Xray if both knees are impacted. There may be quad weakness/atrophy, focal bone tenderness, small knee effusion and limitation in knee extension.
• Patellar Subluxation: Teenage girls w/ recent sensation of patella giving way. It may be tender over the medial patella-femoral ligament. +ve patella apprehension test (subluxated laterally). Linked to atraumatic dislocation. Recurrent instability is common after the first patellar dislocation
• Iliotibial Band Syndrome: Those undergoing repetitive knee flexion (runners/cyclists). Lateral knee tenderness aggr. by the activities mentioned (most often external).

Traumatic:

• Fractures: Mechanisms can be direct blow/trauma/fall. The patient cannot weight-bear & there may be joint deformity/shortening/swelling. Pain on limited ROM. The Ottawa rule is used to determine if an X-ray is needed.
• ACL: Sudden deceleration/direction change injury. Sudden onset of pain, popping sound & rapid swelling within 2 hours. There is lateral knee and joint line tenderness. Specific tests include anterior drawer, Lachman’s and pivot shift tests
• PCL: direct proximal knee trauma w/ knee flexion or hyperextension injury. There is usually a history of high-level trauma (RTC dashboard injury & Sports). Specific tests include the posterior drawer, sag test and quadriceps active test
• Patellar dislocation: direct blow medially/laterally. Has a + apprehension test (like subluxing patella)
• Quadriceps + patellar tendon rupture: Both occur mainly in men. Sudden onset of anterior knee pain during sports or after a fall. Q. Rupture occurs mainly in those >45 yrs old with a distal shift in patella height. P. rupture occurs mainly in those <45 years old with a proximal shift in patella height. There is usually a palpable gap present in both types.
• Meniscal injury/ degenerative tear: twisting/pivoting mechanism or via a degenerative process. Presence of joint swelling, localised joint line pain on anteromedial or anterolateral aspects of the knee. Patients cannot fully flex or extend the knee.
• MCL: Ligament most injured in the knee, result from a direct blow to the lateral aspect of the knee / twisting injury. Medial knee pain & +valgus stress test
• LCL: Result of direct blow to medial aspect of the knee. Lateral knee pain & +varus stress test