Treatment for Medial Meniscus Posterior Root Avulsion
Surgical repair of posterior horn meniscal avulsion is strongly recommended to restore the anatomy and biomechanical function of the meniscus, and to slow or prevent degenerative joint disease. 1
Understanding the Condition
Medial meniscus posterior root avulsion (MMPRA) is a serious knee pathology that can lead to:
- Meniscus extrusion
- Articular cartilage loss
- Osteophyte formation
- Medial joint space narrowing
- Eventually, symptomatic knee osteoarthritis 1
When the posterior root is avulsed, the meniscus cannot resist hoop stresses and fails to shield adjacent articular cartilage from excessive axial load. Research shows that MMPRA results in significant medial meniscal extrusion (3.28 mm) compared to the native knee (1.60 mm) 2.
Treatment Algorithm
1. Initial Conservative Management (First 6-8 weeks)
- Structured physical therapy including range of motion exercises, weight-bearing exercises, and low-impact aerobic activities 3
- Pain management:
- Acetaminophen (up to 4,000 mg/day)
- NSAIDs (oral or topical) with consideration of patient's comorbidities
- Intra-articular corticosteroid injections for acute pain relief 3
2. Surgical Intervention
Surgical intervention is indicated when:
- Conservative management has failed after 6-8 weeks
- Symptoms significantly impact quality of life
- Patient has true mechanical symptoms (especially locked knee) 3
Preferred Surgical Technique
- Arthroscopic repair of the posterior root with transosseous sutures or suture anchors to restore the anatomical footprint 4, 2
- Studies show surgical repair significantly reduces meniscal displacement (from 3.28 mm to 1.46 mm) and gap formation at the defect 2
Alternative Surgical Options
- For degenerative tears that have failed conservative management, arthroscopic partial meniscectomy may be considered, though evidence shows limited benefit 3
- Meniscal transplantation is reserved for salvage situations 1
Post-Surgical Rehabilitation
- Bracing and non-weight bearing for 4-6 weeks following meniscal repair 3
- Regular assessment of pain levels and functional improvement
- Gradual progression of physical therapy as tolerated
Special Considerations
- In skeletally immature patients, diagnosis can be made by MRI showing intense T2 hypersignal at the postero-medial part of the tibial plateau ("bone bruise") 4
- For younger patients with acute traumatic avulsions, repair is particularly important to prevent future degenerative changes 1, 4
- While the American Academy of Orthopaedic Surgeons guidelines state that recommendations for or against arthroscopic partial meniscectomy cannot be made due to inconclusive evidence 5, more recent evidence specifically for root avulsions supports surgical repair to restore meniscal function 1, 2
Pitfalls and Caveats
- Nonsurgical care may relieve symptoms but is unlikely to alter the natural history of meniscal loss or prevent degenerative joint disease 1
- Delay in diagnosis and treatment can lead to progressive articular cartilage damage and osteoarthritis
- MRI is essential for diagnosis, but clinicians should be aware of the specific signs of root avulsion versus standard meniscal tears
- Root avulsion fractures appear to be more common in young male patients after acute knee trauma 6