The role of the lower extremity on patient's cone of economy: an innovative approach.

PURPOSE

To evaluate the effect of the lower extremities on cone of economy (CoE) calculations as well as to propose a novel assessment of seated balance using traditional CoE measurements.

METHODS

36 controls and 82 degenerative lumbar disease (LD) patients, (38 patients with unilateral radiculopathy (UR), 44 patients with neurogenic claudication (NC) with bilateral symptoms), were enrolled in the study. Functional balance tests were performed and recorded by 3D motion capture in both the standing (Romberg) and seated positions. Balance effort and CoE dimensions were calculated.

RESULTS

The lower extremities exert a significant impact on balance, as reflected in the total head (UR: 20.9, NC: 31.5 vs. H: 10.0 cm, p < 0.015), pelvis (UR: 73.2, NC: 110.0 vs. H: 36.4 cm, p < 0.002) and CoM (UR: 17.1, NC: 18.7 vs. H: 4.6 cm, p < 0.001) sway differences observed between LD patients and healthy controls. Significant differences in CoE dimensions were observed as captured by sagittal head (UR: 2.8 vs. H: 0.9 cm, p = 0.014) and pelvis (UR: 2.8 vs. H: 1.4 cm, p = 0.019) range of sway (RoS) and coronal pelvic RoS (UR: 1.1, NC: 1.1 vs. H: 0.6 cm, p < 0.012) between LD patients and healthy controls.

CONCLUSION

This study first provides a novel standardized means of isolating and quantifying the role of the lower extremity on the CoE in patients with LD, which highlights how spinal pathologies may directly impact and/or contribute to compensatory mechanisms in this region. As evidenced by 18.0-93.2 cm of total sway and 1.1-2.8 cm RoS, the lower extremities account for a significant amount of balance effort and CoE dimensions.