Ground reaction force patterns in stroke patients with various degrees of motor recovery determined by plantar dynamic analysis

Background: To study ground reaction force (GRF) patterns in stroke patients with various degrees of motor recovery, using plantar dynamic analysis. Methods: Forty-three people with hemiplegic stroke and 20 healthy subjects were enrolled in the study. Motor impairment (motor recovery and muscle tone) and plantar dynamic data (GRF patterns, peak pressure, and walking speeds) were analyzed. GRF patterns were categorized into four patterns based on the force magnitude (spatial features) through time (temporal features) of the vertical GRF. Then stroke patients were classified into good (patterns III and IV) and poor groups (patterns I and II). Results: Patients with hemiplegic stroke showed characteristic GRF patterns which could be categorized from bimodal (pattern IV) to pathological shapes (I-III). The peak pressures on the paretic side in the metatarsal and toe areas were reduced in stroke patients compared with those in healthy subjects. Walking speeds were higher in the good group than in the poor group (p < 0.05). The peak pressures on both sides in the metatarsal and midfoot areas were lower in the poor group than in the good group (p < 0.05). GRF patterns were highly correlated with walking speeds (r = 0.92, p < 0.01). GRF patterns and walking speeds were positively correlated with motor recovery of knee movement (r > 0.4, p < 0.01), but not with hip and ankle movement or muscle tone in the lower limb. Conclusions: GRF patterns, correlated with walking speeds, indicate underlying motor control of hemiplegic or hemiparetic gait. Knee motor control may be the most important factor in determining walking performance. Plantar dynamic analysis could allow clinicians an alternative assessment in detecting gait changes and planning therapeutic strategies in stroke patients.