What are the causes of posterior knee pain?

Causes of Posterior Knee Pain

Posterior knee pain can be caused by various structural and pathological conditions affecting the posterior compartment of the knee, with the most common causes being cruciate ligament injuries, meniscal pathologies, and tendinopathies.

Common Causes of Posterior Knee Pain

Ligament Injuries

• Posterior Cruciate Ligament (PCL) Injuries

  • Incidence: 3-37% of knee injuries 1
  • Mechanism: Dashboard injuries in motor vehicle accidents or hyperflexion of the knee with plantarflexed foot in sports 1
  • Presentation: Deep posterior knee pain, especially with stairs or squatting

• Anterior Cruciate Ligament (ACL) Injuries

  • Can present with posterior knee pain as a referred symptom 2
  • Often associated with instability and giving way sensations

Meniscal Pathologies

• Posterior Horn Meniscal Tears

  • Prevalence: Affects approximately 12% of adult population 3
  • Presentation: Joint line tenderness (83% sensitivity, 83% specificity) 3
  • Diagnosis: McMurray test (61% sensitivity, 84% specificity) 3

• Meniscal Cysts and Ganglions

  • Can develop from the posterior horn of menisci 2
  • Present with localized posterior knee pain and sometimes palpable mass

Tendinopathies

• Popliteus Tendinopathy

  • Causes posterolateral knee pain 2
  • Often overlooked cause of posterior knee pain
  • May develop ganglion cysts along tendon sheath 2

• Gastrocnemius Tendinopathy

  • Presents with pain at the musculotendinous junction 2
  • Exacerbated by activities involving push-off

• Hamstring Tendinopathy

  • Common cause of posterior knee pain 2
  • Pain typically at the insertion points on the tibia

Joint-Related Conditions

• Baker's Cyst (Popliteal Cyst)

  • Synovial fluid-filled cyst in the popliteal fossa
  • Often secondary to intra-articular pathology
  • May cause posterior fullness, tightness, or pain

• Knee Osteoarthritis

  • Moderate-certainty evidence shows increased risk after various knee injuries 4
  • Can affect posterior compartment causing posterior pain
  • Medial compartment most commonly affected (70-80% of joint load) 4

Inflammatory Conditions

• Arthrofibrosis

  • Post-traumatic or post-surgical complication 2
  • Causes pain and restricted motion
  • May require specialized imaging for diagnosis 4

• Synovitis

  • Can affect posterior compartment 5
  • Often presents with diffuse knee pain and effusion

Less Common Causes

• Abscess or Infection

  • Rare but serious cause of posterior knee pain 5
  • Presents with inflammatory signs (warmth, erythema)
  • Requires prompt diagnosis and treatment

• Tumors and Masses

  • Osteochondromas, synovial tumors 4
  • Typically present as slow-growing masses with pain

• Vascular Conditions

  • Deep vein thrombosis 2
  • Popliteal artery entrapment syndrome

• Neurologic Conditions

  • Common peroneal nerve irritation 2
  • Referred pain from lumbar spine pathology 4

Diagnostic Approach

Clinical Evaluation

• Focused history on mechanism of injury, duration, and aggravating factors
• Physical examination should include:
  • Palpation of posterior structures
  • Range of motion assessment
  • Special tests (McMurray, posterior drawer, etc.)
  • Neurovascular examination

Imaging

• Plain Radiographs

  • First-line imaging for most knee pain 4
  • Limited for soft tissue evaluation

• MRI

  • Gold standard for evaluating posterior knee structures 4
  • Can assess menisci, ligaments, tendons, and cartilage
  • Recommended when radiographs are negative but symptoms persist 4, 6

• Ultrasound

  • Useful for evaluating popliteal cysts, tendinopathies 4
  • Can guide aspirations or injections

• CT Scan

  • May be useful for bony pathology evaluation 4
  • Less sensitive for soft tissue pathologies

Management Considerations

Conservative Management

• Physical Therapy

  • Targeted strengthening exercises for specific diagnoses
  • Quadriceps strengthening for patellofemoral conditions 6
  • Eccentric exercises for tendinopathies 4

• Bracing and Orthoses

  • Unloader braces for unicompartmental osteoarthritis 4
  • Patellar stabilizing braces for patellofemoral conditions 6

• Medications

  • NSAIDs for pain and inflammation
  • Topical analgesics as adjuncts

• Injections

  • Corticosteroid injections for inflammatory conditions 6
  • Consider ultrasound guidance for posterior compartment injections

Surgical Management

• Arthroscopy

  • For meniscal tears, loose bodies, or synovectomy 5
  • Access to posterior compartment requires specialized techniques

• Ligament Reconstruction

  • For complete PCL tears causing instability 1
  • Combined ligamentous injuries usually require surgical management 1

• Osteotomy or Arthroplasty

  • For advanced osteoarthritis with malalignment 6
  • Total knee arthroplasty for tricompartmental disease 6

Clinical Pearls

• Posterior knee pain is often overlooked or misdiagnosed due to complex anatomy
• Always consider referred pain from hip or lumbar spine pathology
• Evaluate for both intra-articular and extra-articular causes
• Post-traumatic conditions may have delayed presentation after the initial injury
• Consider vascular causes in patients with risk factors for atherosclerosis