Best Methods to Assess Hamstring Tendons Before ACL Reconstruction
MRI without contrast is the gold standard imaging modality for preoperative assessment of hamstring tendons before ACL reconstruction, providing superior visualization of tendon morphology, quality, and cross-sectional area compared to ultrasound. 1
Importance of Hamstring Assessment Before ACLR
Proper assessment of hamstring tendons before anterior cruciate ligament reconstruction (ACLR) is critical because:
- Hamstring tendons (semitendinosus and gracilis) are commonly used autografts for ACLR
- Graft quality directly impacts surgical outcomes and long-term stability
- Preoperative knowledge of tendon morphology helps surgical planning
- Inadequate assessment may lead to insufficient graft material
Diagnostic Imaging Options
MRI Assessment (Preferred Method)
- Superior visualization: MRI provides excellent soft tissue contrast for evaluating tendon quality 1
- Complete assessment: Can visualize entire length, cross-sectional area, and potential pathology
- High sensitivity: In studies comparing imaging modalities for hamstring injuries, MRI detected 100% of proximal hamstring avulsions, while ultrasound detected only 58.3% 1
- Timing: Should be performed within 3 days post-injury for optimal assessment 2
Ultrasound Assessment
- Limited utility for comprehensive preoperative planning
- Lower sensitivity (58.3%) compared to MRI (100%) for detecting hamstring injuries 1
- May be useful as a supplementary tool but insufficient as standalone assessment
- Operator-dependent with variable results
CT and 3D-CT Applications
- Primarily used postoperatively to evaluate tunnel position 3
- Can be used to evaluate tendon regeneration after harvest 4
- Not recommended as primary preoperative assessment tool for hamstring tendons
Key Parameters to Assess
Tendon Morphology:
- Cross-sectional area (correlates with strength)
- Length of available tendon
- Presence of accessory slips or anatomical variants
Tendon Quality:
- Signal intensity on T1 and T2-weighted images
- Evidence of prior injury or degeneration
- Muscle-tendon junction integrity
Anatomical Considerations:
- Insertion points and relationship to surrounding structures
- Distal attachment variations
- Muscle belly characteristics
Clinical Correlation with Imaging
Combine imaging with clinical assessment:
- Manual muscle testing of hamstring strength
- Range of motion testing
- Palpation of muscle bellies and tendons 2
- Assessment of referred pain patterns
Research Gaps and Future Directions
Current research gaps include:
- Limited studies directly comparing preoperative hamstring assessment methods
- Need for standardized protocols for hamstring tendon evaluation
- Potential applications of 3D printing for patient-specific planning models
- Correlation between preoperative assessment and postoperative outcomes
Implications for Surgical Planning
Thorough preoperative assessment allows:
- Better prediction of available graft material
- Consideration of alternative graft choices if hamstrings are inadequate
- Planning for potential augmentation if needed
- Improved patient counseling regarding expected outcomes
Postoperative Considerations
Research shows that hamstring tendons can regenerate after harvest:
- Complete gracilis tendon regeneration occurs in most patients 5
- Semitendinosus regeneration occurs in approximately 64% of patients 5
- Regeneration begins proximally and extends distally over time 6
- By 3 months, structures with normal morphology are visible to joint line level 6
Conclusion
MRI remains the most comprehensive and reliable method for preoperative assessment of hamstring tendons before ACLR. The ideal protocol includes MRI without contrast performed within 3 days of injury (if applicable) with specific attention to tendon morphology, cross-sectional area, and quality. Clinical correlation with physical examination findings enhances diagnostic accuracy.