Gait analysis in patients operated on for sacrococcygeal teratoma.

Background: Long-term follow-up of sacrococcygeal teratoma (SCT) is well established; however, little is known about the effects of extensive surgery in the pelvic and perineal region, which involves disruption of muscles providing maximal support in normal walking.
Methods: Thirteen patients operated on at birth for SCT with extensive muscle dissection underwent gait studies with a Vicon 3-D motion analysis system with 6 cameras. Results were compared with 15 age-matched controls. Statistical analysis was performed with Mann-Whitney test; correlations were sought with Spearman's correlation coefficient.
Results: All subjects were independent ambulators, and no statistically significant differences were seen in walking velocity and stride length. However, in all patients, toe-off occurred earlier (at 58% +/- 1.82% of stride length) than controls (at 65.5% +/- 0.52%; P <.05). On kinetics, all patients exhibited, on both limbs, a significant reduction of hip extensory moment (-0.11 +/- 0.11 left; -0.16 +/- 0.15 right v 1.19 +/- 0.08 Newtonmeter/kg; P <.05) and of ankle dorsi/plantar moment (-0.07 +/- 0.09 right; -0.08 +/- 0.16 v -0.15 +/- 0.05 Nm/kg, p < 0.05). Knee power was also significantly reduced (0.44 +/- 0.55 right, 0.63 +/- 0.45 left v 0.04 +/- 0.05 W/kg), whereas ankle power was increased (3 +/- 1.5 right; 2.8 +/- 0.9 left v 1.97 +/- 0.2 W/kg; P <.05). No statistically significant correlation was found between tumor size and either muscle power generation or flexory/extensory moments.
Conclusions: Patients operated on for SCT exhibit nearly normal gait patterns. However, this normal pattern is accompanied by abnormal kinetics of some ambulatory muscles, and the extent of these abnormalities appears to be independent of tumor size. A careful follow-up is warranted to verify if such modifications are stable or progress over the years, thereby impairing ambulatory potential or leading to early arthrosis.