A medical device-includes a polymer stent crimped to a catheter having an expansion balloon. The stent is crimped to the balloon by a process that includes heating the stent to a temperature below the polymer's glass transition temperature to improve stent retention without adversely affecting the mechanical characteristics of the stent when later deployed to support a body lumen.

A steering shaft assembly includes a male shaft having a plurality of splines formed thereon, each of the splines terminating at a spline end, wherein each of the spline ends form an angle of about 90 degrees relative to a longitudinal direction of the splines. The steering shaft assembly also includes a female shaft including a plurality of stakes located proximate an end of the female shaft, the stakes retaining the male shaft at an interface between the stakes and the spline ends.