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Strain-gauge evaluation of lunate unloading procedures
V R Masear1, E G Zook, D R Pichora
1Division of Orthopaedic Surgery, University of Alabama, Birmingham.
The Journal of Hand Surgery
|May 1, 1992
Summary
Ulnar lengthening effectively reduces lunate strain, unlike other wrist fusion procedures. This surgical approach is the most reliable for unloading the lunate bone.
Area of Science:
- Orthopedic Surgery
- Biomechanics
- Hand and Wrist Anatomy
Background:
- The lunate bone is critical for wrist function and susceptible to damage from abnormal loading.
- Understanding the biomechanical effects of surgical interventions is essential for effective treatment of wrist conditions.
Purpose of the Study:
- To evaluate the effectiveness of three surgical procedures in reducing load on the lunate bone.
- To compare the biomechanical outcomes of scaphotrapeziotrapezoid arthrodesis, capitohamate arthrodesis, and ulnar lengthening on lunate strain.
Main Methods:
- A biomechanical study using 20 preserved cadaveric limbs.
- Strain gauges were utilized to measure lunate strain before and after simulated surgical procedures.
- Three procedures were tested: scaphotrapeziotrapezoid arthrodesis, capitohamate arthrodesis, and ulnar lengthening.
Main Results:
- Ulnar lengthening by 3 mm demonstrated the most significant reduction in lunate strain.
- Capitohamate arthrodesis reduced compressive strain but increased shear strain on the lunate.
- Scaphotrapeziotrapezoid fusion led to increased compressive and shear strain in the lunate.
Conclusions:
- Ulnar lengthening to achieve neutral variance is the most effective method for unloading the lunate.
- The findings provide critical biomechanical data for surgical decision-making in wrist reconstruction.
- Alternative fusion procedures may exacerbate strain on the lunate, necessitating careful consideration.