What is the management for an avulsion of the right semimembranosus tendon?

Management of Semimembranosus Tendon Avulsion

MRI is the imaging modality of choice for diagnosing semimembranosus tendon avulsion, followed by a treatment approach that includes relative rest, NSAIDs, and rehabilitation exercises, with surgical repair indicated for complete tears or cases that fail conservative management.

Diagnostic Approach

Initial Imaging

• Plain radiography should be performed first to identify any associated bony avulsion fractures or other osseous abnormalities 1
• MRI is the preferred advanced imaging modality for definitive diagnosis with 95% sensitivity and specificity for tendon tears, degeneration, and chronic tendinopathy 1
• Ultrasound is an alternative option with good specificity (94%) but lower sensitivity (58%) for tendon pathology 1

Key MRI Findings

• Complete tendon disruption at or near insertion site
• Tendon retraction
• Associated edema and hemorrhage
• Possible associated injuries to other structures (PCL, menisci, capsule) 2

Treatment Algorithm

Conservative Management (for partial tears or tendinopathy)

1. Relative Rest

   • Reduce activities that cause pain
   • Avoid complete immobilization to prevent muscle atrophy 1
   • Continue activities that don't worsen symptoms

2. Pain Management

   • Ice therapy (10-minute applications through wet towel) for acute pain relief 1
   • NSAIDs for pain control and possible anti-inflammatory effect 1
   • Topical NSAIDs may be considered to avoid systemic side effects 1

3. Rehabilitation

   • Tensile loading exercises to stimulate collagen production
   • Eccentric strengthening exercises
   • Stretching exercises for the posterior thigh muscles 1, 3

4. For Persistent Cases (>3 months)

   • Consider corticosteroid injection at the tendon insertion site 3
   • Caution: corticosteroid injections directly into the tendon substance should be avoided as they may inhibit healing and reduce tensile strength 1

Surgical Management (for complete tears)

• Indications for surgery:

  • Complete rupture of the semimembranosus tendon 4, 5
  • Failed conservative management after 3-6 months
  • Athletes or high-demand patients 4

• Surgical options:

  • Direct tendon repair for acute tears
  • Tendon rerouting and reattachment for chronic cases 3
  • Repair of associated injuries (if present) such as capsular tears or avulsion fractures 2

Post-Treatment Monitoring

• Regular clinical assessment of pain and function
• Progressive return to activities based on functional improvement
• Follow-up imaging (MRI) may be considered for persistent symptoms or to evaluate healing in surgically treated cases 1

Important Considerations

• Semimembranosus tendon avulsions are rare but may be underdiagnosed 3
• These injuries can be isolated or associated with other knee injuries, particularly PCL tears 2
• Complete ruptures can lead to secondary hamstring muscle atrophy if not properly treated 5
• Careful assessment of the posteromedial knee structures is essential as the semimembranosus has multiple distal insertions intimately associated with the posterior capsule, medial meniscus, and posterior oblique ligament 6

Pitfalls to Avoid

• Misdiagnosis as simple knee strain or meniscal pathology
• Inadequate imaging (plain radiographs alone are insufficient)
• Overly aggressive early rehabilitation
• Injecting corticosteroids directly into the tendon substance rather than peritendinously 1
• Prolonged immobilization leading to muscle atrophy and deconditioning 1