TTD payments stop when you have reached MMI (Maximum Medical Improvement), becasue your PTP has determined that your condition is relatively stable, and is not expected to substantially improve or worsen over the next year or so. Even if you are declared MMI, it does NOT mean that your condition does not require contined medical treatment or Future Medical Treatment.
Also,... keep in mind that WC is there to provide treatment to the EE due to a work related injury... and a RTW as soon as possible...
Your TTD benefits end becasue as Charles said, you have reached a state where your doctor considers you to be P&S/MMI, which means that with or without additional treatment your condition is not expected to change better or worse in the next 12 months... and you are capable of returning to work...although that RTW may not be in your previous position/job.
Unless you settle your case by a C&R, you are entitled to medical treatment to this injury/body part, and possibly to a 'compensable consequence' for life.
This is where the issue of "reasonable accomodation" comes into the picture. And your ER's mandate to partake in the 'interactive process'...and ADA/FEHA rules/laws.
The popular belief that you will receive benefits from your ER/IC until you are completely recovered from your injury is unfortunately WRONG...WC is there to get the IW back on his/her feet, and a return to some kind of 'gainful employment'...NOT necessarily the job you "know and love"...
"Gainful employment'' is as determined by the Social Security Adm are those people capable of earning more than $940.00/month.