Knee Pain

Pathophysiology

• Patellofemoral friction can be exacerbated by a shallow trochlear groove and maltracking due to weak medial quadriceps (e.g. vastus medialis obliquus) or tight lateral quadriceps and hamstrings

• Excessive ankle pronation may transfer abnormal stresses up the kinetic chain to the knee

• Microtrauma from repetitive use, prolonged kneeling, or athletic activity leads to gradual collagen breakdown and inflammation

• Acute or chronic trauma (e.g. direct blows, twisting injuries) can cause structural damage to ligaments or menisci and worsen patellar alignment

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Differentials

• Knee-related: Patellofemoral pain syndrome (PFPS), chondromalacia patella, patellar instability/dislocation, patellar osteoarthritis

• Ligaments/tendons: Quadriceps or patellar tendinopathy, meniscal tears, ACL/PCL injuries

• Attachment injuries: Iliotibial band (ITB) syndrome, Osgood-Schlatter disease, pes anserine bursitis

• Bursal inflammation: Prepatellar, suprapatellar, infrapatellar bursitis, Baker’s cyst

• Bone: Knee osteoarthritis, osteochondritis dissecans, rare tumours

• Referred pain: Lumbar radiculopathy (L3–L4 nerve roots), hip osteoarthritis

• Systemic: Rheumatoid arthritis, psoriatic arthritis, other inflammatory arthritides

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Management

• Non-pharmacological

  • Strengthening of the medial quadriceps (especially VMO) and stretching tight lateral quadriceps or hamstrings

  • Orthotics if ankle overpronation is contributing to maltracking or foot malalignment

  • Activity modification with relative rest for acute flare-ups (e.g. Osgood-Schlatter typically allows continued sport if pain is tolerable)

  • Physiotherapy focusing on muscle balance, core stability, and biomechanical corrections (including gait retraining)

• Pharmacological

  • NSAIDs to reduce pain and inflammation

  • Ice application for 10–20 minutes post-exercise to relieve acute inflammation

  • Consider topical NSAIDs or oral analgesics based on severity and patient comorbidities

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Key Conditions

• PFPS (Patellofemoral Pain Syndrome)

  • Anterior knee pain worsened by stairs, running, prolonged sitting (cinema sign)

  • May involve maltracking, patellar tilt, or underlying cartilage wear (chondromalacia patella)

• Patellar Instability

  • Lateral displacement or dislocation episodes with a sensation of “giving way”

  • Often linked to trauma or congenital malalignment of the patella

• Tendinopathy (Patellar or Quadriceps)

  • Local pain, tenderness, and potential thickening at the tendon insertions

  • Aggravated by jumping or rapid deceleration (“jumper’s knee”)

• ITB Syndrome

  • Lateral knee pain provoked by running or repetitive knee flexion

  • Improves with ITB stretching, foam rolling, and hip abductor strengthening

• Bursitis

  • Local swelling, tenderness over the affected bursa (e.g. prepatellar bursitis from kneeling)

  • Baker’s cyst (popliteal cyst) can present with fullness in the posterior knee and occasional calf pain

• Osteochondritis Dissecans

  • Loss of subchondral bone support leading to locking, clicking, swelling, and limited extension

  • More common in adolescents and young adults

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Red Flags

• Knee swelling with fever or severe systemic symptoms suggests septic arthritis or inflammatory arthritis (e.g. gout)

• Mechanical locking or inability to extend fully points to meniscal tears or loose bodies

• Persistent night pain or significant weight loss raises suspicion of malignancy or infection

• Major trauma with an unstable knee often indicates ACL rupture or complex ligamentous injury

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Interventions

• Injections

  • Corticosteroids for localised inflammation (e.g. pes anserine bursitis, recalcitrant PFPS)

  • Hyaluronic acid for osteoarthritis, although evidence is mixed

  • Platelet-rich plasma (PRP) may be considered in refractory tendinopathies

• Surgical Referral

  • Recurrent patellar instability requiring repair or realignment

  • Large or complex meniscal tears with mechanical symptoms

  • Persistent pain or instability unresponsive to conservative measures