Can tendinitis occur behind the knee?

Can Tendinitis Occur Behind the Knee?

Yes, tendinitis can definitely occur behind the knee, most commonly involving the popliteus tendon, hamstring tendons, and gastrocnemius tendon. 1, 2, 3, 4

Specific Tendons Affected in the Posterior Knee

Popliteus Tendinitis

• Popliteus tendinitis is a recognized but relatively infrequent cause of posterior and posterolateral knee pain that is often misdiagnosed 2, 3, 4
• This condition is particularly relevant for serious runners and triathletes, as symptoms can be disabling 2
• The popliteus tendon is located in the popliteal region and can be visualized sonographically between the medial head of gastrocnemius and semimembranosus tendon 1
• Patients present with posterolateral knee pain, instability, popliteus tenderness, and a positive Garrick test 4

Hamstring Tendinitis

• Tendinitis of the hamstring tendons is listed as one of the most common causes of posterior knee pain 3
• The semimembranosus tendon is specifically mentioned as a structure in the popliteal region that can develop pathology 1

Gastrocnemius Tendinitis

• Gastrocnemius tendinitis is recognized as a less common but documented cause of posterior knee pain 3
• The gastrocnemius muscle has a bursa in the popliteal region that can accumulate fluid (Baker's cyst), and the tendon itself can become inflamed 1

Diagnostic Approach

Clinical Examination

• Look for tenderness in the popliteal region, specifically between the medial head of gastrocnemius and semimembranosus tendon 1
• Assess for posterolateral knee pain with specific provocative maneuvers 4
• Consider the Garrick test for popliteus tendinopathy 4

Imaging Studies

• Ultrasound is particularly useful for examining the popliteal region and can detect tendinitis, tenosynovitis, and tendon tears 1
• MRI is the criterion standard for diagnosing popliteus tendinopathies and can show tendon thickening, heterogeneous signal, and associated pathology 1, 4
• Plain radiographs should be obtained first to rule out bony abnormalities, though they typically don't show soft tissue tendon changes 1

Important Differential Diagnoses

When evaluating posterior knee pain, consider these other common causes that can mimic or coexist with tendinitis:

• Baker's cyst (popliteal cyst) - fluid accumulation in the gastrocnemius or semimembranosus bursa 1
• Meniscal tears or ganglions 3
• Bursitis 3
• Deep venous thrombosis (can be mimicked by ruptured Baker's cyst) 1

Treatment Approach

Conservative Management (First-Line)

• Rest and activity modification to prevent ongoing damage 1, 4
• Physical therapy with quadriceps strengthening 4
• NSAIDs for pain management 1
• Eccentric strengthening exercises (proven beneficial for tendinopathies) 1
• Cryotherapy for short-term pain relief 1

Advanced Treatment (For Refractory Cases)

• Corticosteroid injections may be considered for severe or refractory popliteus tendinopathy 4
• Arthroscopy remains the criterion standard for definitive diagnosis and treatment of popliteus tendon injuries 4

Common Pitfalls

• Popliteus tendinitis is frequently misdiagnosed because it is relatively uncommon and presents with nonspecific posterior knee pain 2, 4
• Failure to detect pathology on ultrasound does not rule out tendinitis or other posterior knee pathology 1
• Don't confuse a Baker's cyst with tendinitis - ultrasound can differentiate by showing the characteristic comma-shaped extension between the gastrocnemius and semimembranosus 1