The association of equinus and primary genu recurvatum gait in cerebral palsy.

Primary genu recurvatum (GR) is less investigated and data presenting the prevalence among patients with bilateral spastic cerebral palsy (BSCP) is lacking in the literature. Equinus is mentioned as one of the main underlying factors in GR, but its influence on the severity and onset type of GR is mainly unanswered, yet. Hence, the purpose of this retrospective study was to assess the prevalence of GR in a large sample size in children with BSCP and to investigate sagittal plane kinematics to evaluate the influence of equinus on different GR types using data of three-dimensional gait analysis. GR was defined as a knee hyperextension of more than one standard deviation of an age matched control group during stance phase in either one or both of the limbs. Primary GR was defined as a GR without having previous surgery regarding the lower extremity, no selective dorsal rhizotomy and/or interventions like botulinum toxin injection, shock wave therapy or serial casting during the last 6 months in the patient history. In a retrospective study 463 patients with BSCP (GMFCS Level I-III) received three-dimensional gait analysis and were scanned for the presence of primary GR. Finally, 37 patients (23 males, 14 females) matched the determined inclusion criteria and were therefore included for further analysis in this study. Out of those patients seven walked with orthoses or a walker and were excluded from further statistical comparison: Kinematics of the lower limbs were compared between patients having severe (knee hyperextension>15°) and moderate (knee hyperextension 5-15°) GR and between patients showing an early (first half of stance phase) and a late (second half of stance phase) GR. Primary GR was present in 37 patients/52 limbs (prevalence 8.0/5.6%). Severe GR was associated with a decreased ankle dorsiflexion compared with moderate GR. Early GR showed an increased knee hyperextension compared to late GR. In conclusion GR is less frequent compared with crouch or stiff gait. Our findings support the importance of equinus as a major underlying factor in primary GR. In this context the influence of equinus seems to be more important in early GR.