Shriners Hospitals for Children - Spokane

One technique for distal femur and proximal tibia epiphysiodesis to treat leg length inequality is a single-incision percutaneous technique using reamers and curettes. The purpose of this study is to demonstrate the efficacy and reliability of this technique by quantifying the growth arrest produced from this method. Patients who underwent distal femur and proximal tibia epiphysiodesis with a single-incision percutaneous technique were retrospectively reviewed. Using scanogram data, derivative formulas of both the multiplier and arithmetic methods were used to predict bone length after physeal arrest at maturity. Patients included had at least 2-year follow-up after surgery. Predicted bone lengths were then compared to actual bone lengths obtained via scanogram at final follow-up. A total of 46 patients were included in the study (27 males; 19 females). Average age at surgery was: males 14.5 years, females 12.4 years. Surgery was performed on 40 distal femurs and 25 proximal tibias. Postoperative femurs demonstrated an actual mean length of 44.75 cm. Predicted femur bone lengths utilizing the multiplier and arithmetic methods were 45.08 and 44.08 cm, respectively. Postoperative tibias demonstrated an actual mean length of 38.12 cm. Predicted tibia lengths utilizing the multiplier and arithmetic method were 38.30 and 38.02 cm. No significance was found between actual and predicted bone lengths for both tibias and femurs. This study demonstrates that a single-incision percutaneous epiphysiodesis technique reliably arrests the growth as expected. Surgeons can confidently and accurately employ this technique to successfully treat leg length inequality.

Biomechanical optimization models are often used to estimate muscular and intervertebral disc forces during physical exertions. The purpose of this study was to determine whether an optimization-based biomechanical model predicts torso muscular activity of males and females equally well. The Minimum Intensity Compression (MIC) model, which has been extensively applied in industrial ergonomic task analysis, was used to estimate muscle forces for 3D moments. Participants (6 M, 6 F) performed 18 isometric exertions resisting 3D L3/L4 moments while electromyographic (EMG) activity was recorded for 8 muscles. Overall, model force estimates correlated better with male EMG activity (R2 = 0.43) than with female EMG activity (R2 = 0.33). Model force estimates of 4 muscles (LRA, RRA, REO, and RES) correlated better with male EMG activity than with female EMG. We conclude that trunk muscle forces estimated by current biomechanical modeling do not correlate equally well to male and female EMG activity. Future research needs to address validation or improvement of biomechanical trunk models for females.