What is the best course of action for a healthy 25-year-old male with persistent thigh pain following an episode of acute knee pain and swelling, now with improved swelling but no instability, joint line tenderness, clicking, or locking?

Clinical Assessment and Management

Most Likely Diagnosis

This clinical presentation is most consistent with referred pain from hip pathology or proximal quadriceps/iliopsoas pathology rather than an intra-articular knee problem, given the resolution of mechanical symptoms (locking, clicking) and absence of joint line tenderness, but persistence of thigh pain. 1

Diagnostic Approach

Initial Imaging

• Obtain standard knee radiographs (AP and lateral views at 25-30° flexion) to rule out fracture or other bony pathology, even though Ottawa Knee Rules may not be met 2, 3
• The absence of joint line tenderness makes meniscal pathology unlikely (joint line tenderness has 83% sensitivity for meniscal tears) 1
• The resolution of locking and clicking suggests the acute mechanical component has resolved 1

Critical Physical Examination Findings to Assess

• Evaluate hip range of motion and perform FABER test - thigh pain radiating from the knee may originate from hip pathology 4
• Palpate the proximal quadriceps and iliopsoas insertion - persistent thigh pain without knee findings suggests proximal muscle or tendon pathology 2
• Assess for effusion on lateral radiograph - if present, this would indicate ongoing intra-articular pathology requiring further investigation 3, 5

Management Algorithm

If Radiographs Are Normal and No Effusion Present:

Conservative management with focus on proximal muscle rehabilitation is the appropriate first-line approach 1, 6

• Initiate physical therapy targeting hip and proximal quadriceps strengthening - exercise therapy is first-line treatment for most knee pain conditions 1
• NSAIDs for pain control - effective for tendon-related pain and safe for short-term use 2
• Avoid complete immobilization - tensile loading stimulates collagen production and proper healing 2
• Consider eccentric exercise protocols - proven beneficial for tendinopathy 2

If Effusion Present on Imaging:

• Consider joint aspiration for diagnostic purposes if effusion persists, to rule out inflammatory or infectious causes 5, 7
• Intra-articular corticosteroid injection may be appropriate if inflammatory effusion is confirmed 5

Red Flags Requiring Advanced Imaging (MRI):

• Persistent mechanical symptoms returning (true locking, not just stiffness) 1
• Inability to bear weight after 4-6 weeks of conservative management 6
• Progressive thigh pain or weakness suggesting structural pathology 4

Common Pitfalls to Avoid

• Do not assume all knee pain originates from the knee joint - referred pain from hip or proximal thigh structures is common in young active patients 4
• Do not order MRI without recent radiographs first - approximately 20% of patients inappropriately receive MRI without plain films 3
• Do not interpret resolution of mechanical symptoms as complete healing - the persistent thigh pain indicates ongoing pathology requiring treatment 2, 6
• Do not apply corticosteroid injections into tendon substance - peritendinous injections may inhibit healing and reduce tensile strength 2

Follow-Up Timeline

• Re-examine at 3-5 days if not already done - swelling and pain can limit initial examination accuracy 2, 6
• Reassess at 4-6 weeks - if no improvement with conservative management, consider MRI to evaluate for occult meniscal tear, cartilage injury, or proximal muscle/tendon pathology 1, 6