An implantable medical device having a soft tissue interfacing surface comprises at least one soft actuatable capsule having a soft tissue interfacing deflectable membrane configured for cyclical deflection upon actuation of the capsule to modulate the biomechanics of the soft tissue interface during use. The actuatable capsule may comprise an actuation chamber containing a first fluid, a therapeutic chamber containing a second fluid, a deflectable membrane separating the actuation chamber and therapeutic chamber, and an actuation conduit in fluidic communication with the actuation chamber for pneumatic actuation of the actuation chamber. The therapeutic chamber comprises the soft tissue interfacing deflectable membrane which is configured to cyclically deflect during actuation of the capsule and modulate the biomechanics of the soft tissue interface by altering one or more of strain, fluid flow and cellular activity in peri-implant tissue at the soft tissue interface. Methods of reducing fibrotic encapsulation of an implantable medical device are also described.