Gait Analysis in Patients Operated on for Sacrococcygeal Teratoma By Antonio Zaccara, Barbara D. Iacobelli, Ottavio Adorisio, Maurizio Petrarca, Giuseppe Di Rosa, Marcello M. Pierro, and Pietro Bagolan Rome, Italy Background: Long-term follow-up of sacrococcygeal tera- toma (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 pro- viding 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; correla- tions were sought with Spearman’s correlation coefficient. Results: All subjects were independent ambulators, and no statistically significant differences were seen in walking ve- locity and stride length. However, in all patients, toe-off occurred earlier (at 58%  1.82% of stride length) than con- trols (at 65.5%  0.52%; P  .05). On kinetics, all patients exhibited, on both limbs, a significant reduction of hip ex- tensory 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 accom- panied by abnormal kinetics of some ambulatory muscles, and the extent of these abnormalities appears to be indepen- dent 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. J Pediatr Surg 39:947-952. © 2004 Elsevier Inc. All rights reserved. INDEX WORDS: Sacrococcygeal teratoma, gait analysis. W ITH AN INCIDENCE of 1 in 40,000 live births, sacrococcygeal teratomas (SCT) represent the most common neonatal tumor; girls are affected 4 times as often as boys. 1 Thanks to the introduction of intensive multiagent chemiotherapy, a survival rate of greater than 80% may be attainable, even in children with metastatic disease; 2 on the other hand, technical refinements in surgical technique allow complete resection of large benign lesions. Not surprisingly, increased survival rate has produced a significant number of follow-up studies, the majority of which have addressed long-term fecal and urinary con- tinence. 3,4 On the contrary, there is only little mention in the literature about long-term effects of extensive gluteal and perineal dissection, which involves muscles like gluteus maximus, which provide a significant contribu- tion to support in normal walking. 5 In this respect, gait analysis may prove to be a useful tool in evaluating such muscle deficiency and its effects on gait patterns. MATERIALS AND METHODS The records of all patients operated on at birth for SCT at our institution from 1990 to 2002 were reviewed retrospectively. Particular attention was directed to the following factors: tumor type (AAP classification), 6 histologic appearance, and operative notes. Parents of patients of age suitable for cooperation were asked to answer a questionnaire regarding presence or absence of functional sequelae as well as to participate in a gait analysis study with concom- itant clinical assessment. Clinical assessment consisted of a complete neurologic examination with evaluation of motor and sensory deficits angle definitions and strength measurements. Gait studies were per- formed using a Vicon 3-dimensional motion analysis system with 6 cameras (Vicon Motion Systems, Oxford Metrics Group, UK) and 2 AMTI force plates (AMTI, Watertown, MA). This is a an optical motion capture system that has long been accepted to analyze a patient’s gait. 7 Multiple gait cycles were recorded, and an average gait cycle was chosen to evaluate motion. Time and distance measurements included velocity (centimeters per second), cadence (number of steps per minute), and stride length (distance from 1 foot strike to next foot strike by the same foot). Key values from the motion data were selected for further analysis; for this purpose, hip and knee flexory/extensory and ankle dorsi/plantar moments (values in Newtometer per kilogram), hip, knee and ankle power (values in Watt per kilogram) were calcu- lated. 8 Reflecting skin markers were placed over standardized anatomic From the Units of Newborn Surgery and Pediatric Rehabilitation, Bambino Gesu ` Children’s Hospital, Rome, Italy. Presented at the 55th Annual Meeting of the Section on Surgery of the American Academy of Pediatrics, New Orleans, Louisiana, October 31-November 2, 2003. Sponsored by Charles N. Paidas, MD. Address reprint requests to Antonio Zaccara, MD, Newborn Surgery Unit, Bambino Gesu ` Children’s Hospital, P.zza S. Onofrio, 4, 00165 Rome, Italy. © 2004 Elsevier Inc. All rights reserved. 0022-3468/04/3906-0034$30.00/0 doi:10.1016/j.jpedsurg.2004.03.026 947 Journal of Pediatric Surgery, Vol 39, No 6 (June), 2004: pp 947-952