The proposed study will answer the key question whether Botulinum toxin injection in the spastic (tight) lower limb muscles following stroke improves walking and the quality of life.

INTERVENTION: The intervention group will receive BT injection (up to 400 units of Botulinum toxin, Allergan reconstituted with 2ml of normal saline) into the lower limb spastic muscles, single injection. The specific dose is determined by assessing the spasticity by Modified Ashworth Scale (MAS) and the number of spastic muscle. The study physician (myself for this trial) will administer the intervention and also the placebo. The trial will be conducted in the specialised multidisciplinary spasticity clinic consisting of the rehabilitation physician, nurse, physiotherapist, and the orthotist. Besides the intervention (active or placebo) all participants will receive a structured physiotherapy program. Strategies will be placed to monitor and ensure the reliability and validity of the interventions. The process fidelity i.e. the consistency in which intervention content will be delivered, will be monitored by the study physician and the nurse. The content fidelity i.e. delivery of the intervention components delivered as per prescription, will be ensured by the study physician and the physiotherapist. We will employ some strategies such as treatment manuals, written exercise program and telephone intervention to ensure intervention adherence. Structured physiotherapy will be delivered by a senior physiotherapist experienced in treating the stroke patients. The therapy will consist of stretching, balancing, strengthening exercises, and gait training. Each session will last for 45 minutes (duration) in the physiotherapy department of the Queen Elizabeth Hospital, two times per week (frequency) and will be of moderate intensity (Borg's scale 4‐6). A similar home exercise program will also be developed. Participants will undergo baseline assessment and follow ups as described in the protocol at three weeks, three months and five months. Home exercise program will be monitored by the physician and the physiotherapist by making telephone calls CONDITION: Lower limb spasticity Post stroke lower limb spasticity Spasticity Stroke PRIMARY OUTCOME: 2 Minutes Walking Distance Gait velocity ; ; The gait velocity will be measured in the Gait Rite (Electronic walkway) along with recording of other temporospatial gait parameters. ; ; SECONDARY OUTCOME: Berg Balance Score Goal Attainment Scale (GAS) Quality of Life (SF 12) Timed Up and Go INCLUSION CRITERIA: • Male or female subjects aged 20 to 80 years of age are eligible for this study if they had a stroke resulting in focal spasticity in the knee causing stiff knee and/or equinovarus deformity, as demonstrated by a score of more than 3 for quadriceps (rectus femoris), gastrocnemius, soleus, tibialis posterior, flexor hallucis longus or flexor digitorum longus on the Modified Ashworth Scale. • All patients should be walking normally prior to stroke. Any patients with lower limb spasticity (MAS 3+) resulting in a limp, or any difficulty in weight bearing on the leg or walking such as reduced speed of gait following stroke will be included.