The STAK Knee Stretcher is a clinically proven device designed to improve knee movement after TKR, surgery, or injury. Unlike standard exercises, STAK enables high-intensity stretching at home, helping break down scar tissue and improve flexibility. Research in The Bone & Joint Journal shows users gain 30° flexion and 9° extension in eight weeks. Used by NHS Trusts and private clinics, STAK halves MUAs and supports remote rehab. A new extension add-on targets severe stiffness for better recovery.