Classification of the reduced vertical component of the ground reaction force in late stance in cerebral palsy gait.

Children with cerebral palsy (CP) often experience significant problems supporting their bodyweight (BW) and decelerating the downward velocity of the centre of mass (CoM) in late stance. This is seen as a decreased second peak of vertical ground reaction force (GRF) nominated FZ(2). This study categorises gait data by the degree of reduced FZ(2). Kinetic data were analysed from a CP database. Data from 129 patients, able to walk barefoot unaided, were investigated. Of these, 84 had kinetic data, 59 diplegics (both legs) and 15 hemiplegics (affected leg only), thus providing data from 133 legs. A reduced FZ(2) was observed in 116 legs (87%). Of the 133 legs, 44% failed to generate FZ(2)>BW. By including the Type 2 data this figure rises to, a staggering 66% who are having difficulty supporting BW at this stage of the stance phase. Only 12% of the legs showed a normal pattern (FZ(2) approximately equal to FZ(1)). In conclusion, the majority of CP children referred to the gait laboratory exhibited some degree of reduced FZ(2) and can be categorised as having a 'Ben Lomonding' gait pattern. 'Ben Lomonding,' is the term used to describe this phenomenon of reduced FZ(2), as the shape of the GRF graph resembles the shape of the Scottish mountain, Ben Lomond, which has two peaks, the second peak being much smaller than the first. Crucially, clinicians should be aware that nearly half of the CP children in this study were in difficulty supporting their BW in late stance and must use compensatory mechanisms to prevent collapse of the affected limb.