Measurement of the bone mineral density in the tunnel region during the anterior cruciate ligament reconstruction / 中华骨科杂志

ABSTRACT

Objective To compare the bone mineral density of the regions of femoral and tibial tunnels for anterior cruciate ligament(ACL)reconstruction in order to provide reference for the choice of optimal screw diameter for interference fixation.Methods Thirty healthy volunteers aged from 18 to 35 years were enrolled in our study,and the dual-energy X-ray absorptiometry(DEXA)was used to measure the bone mineral density of femoral and tibial tunnel regions of the right knee.All the right knees of the volunteers were also scanned by spiral CT and three-dimensional reconstruction technique was utilized to determine the circular sections that pass through the longitudinal axis of the femoral and tibial tunnels separately.The CT gray scale values of the Sections were measured.From August to October 2010,9 patients who had been diagnosed as ACL rupture underwent the operation of ACL reconstruction,and cylindrical cancellous bone peg was removed from the femoral and tibial tunnel respectively during the operation.Volumetric bone mineral density of the bone pegs were measured by using a standardized immersion technique according to Archimedes’ principle.Results Measured by DEXA,bone density of the femoral tunnel region arid tibial tunnel region were(1.162±0.034)g/cm2 and(0.814±0.038)g/cm2 respectively.The difference was significant between the femoral and tibial tunnel region(t=9.11,P=0.000).The CT gray scale value of the section for femoral tunnel region was(211.7±11.5)Hu,while that of the tibial tunnel region was(104.9±7.4)Hu.There was statistically significant difference between them(t=10.15,P=0.000).The volumetric bone mineral density of the bone peg from femoral tunnel and tibial tunnel were(2.80±0.88)g/cm3 and(1.88±0.59)g/cm3 respectively.The difference was statistically significant(t=4.32,P=0.002).Conclusion For ACL reconstruction,bone mineral density of femoral tunnel region is higher than that of the tibial tunnel.