Rotational Alignment in the Coronal Plane During Tibial Tubercle Osteotomy Background & Significance

Significance & Hypothesis: Prior literature has demonstrated the effects of translation of the tibial tubercle during tibial tubercle osteotomy (TTO) procedures in both the sagittal and transverse planes but there has not been much investigation into the effects of adjustment of the rotation alignment of the tibial tubercle in the coronal plane. Since changes in the positioning of the tibial tubercle in all three planes has the opportunity to yield significant physiological changes in range of motion, the results of this study would possibly provide insight on how to optimize this procedure. Specifically, a margin of error determination may be made from the data to guide surgeon fixation of the tubercle post osteotomy. This study is aimed at the effects of variations to the tibial tubercle in the TTO procedure, specifically investigating effects of rotational alignment of the tibial tubercle in the coronal plane. The hypothesis of this study is that coronal plane rotation during TTO must be within 5 degrees of native orientation to prevent poor patellofemoral kinematic effects. Materials & Methods: At least 10 frozen, fresh, prepared specimens would have the musculature of the thigh exposed with specific muscles sutured to accommodate loads of weight specific to each muscle type to achieve standardized range of motion. The specimens would be secured into a knee-rig structure allowing full flexion and extension. Each specimen would be initially range of motion tested and used as control for comparison to the resulting range of motion after the TTO is performed. A tracking system will be utilized, recording patellar range of motion data with 6 degrees of freedom during leg range of motion testing cycles. For each specimen, initial native patellar motion would be documented, and then compared against resultant patellar motion as the degree of tibial tubercle rotational alignment in the coronal plane is incrementally adjusted. Comparison will involve evaluation of the Euler angle changes of the native patella against measurements as the rotational alignment is adjusted. A repeated one-way ANOVA will be used with a post hoc tukey test to find statistical significance. Results: Pathologic rotational motion of the tibia on femur has been noted grossly with alterations of coronal alignment of the tibial tubercle, especially at the end range of extension. Detailed statistical analysis is currently pending on gathered data. Conclusions: Rotational alignment modification of the patellar tendon insertion, the tibial tubercle, causes unilateral unloading and loading of the quadriceps musculature. This change in force vectors results in gross change to lower extremity flexion and extension mechanics. Further data analysis is required to make specific comments on the details of this change.