It appears as if the Rangers will be unable to buy out the final season of Chris Drury’s contract because of a degenerative condition in the captain’s left knee that apparently will render him medically unable to play next season, The Post has learned.

While Drury has yet to file the necessary paperwork, sources report he plans to do so. The Rangers, who had been planning a buyout, could file a grievance against Drury, but that is a remote possibility, at best.

Mounting a challenge is problematic on numerous levels, but winning a grievance would cost CEO Jim Dolan approximately $2.7 million in cash, given insurance ramifications.

This, of course, is bad news for Drury, who more than likely will be facing the end of a distinguished 12-year NHL career at the age of 35, which he turns in August.

But this also is bad news for the Rangers, who will contend with complex cap issues both over the summer and for next season.

The inability to buy out an injured player means that Drury’s full $7.05 million charge will remain on the Blueshirts’ summer cap, which can exceed the 2011-12 season cap by 10 percent.

Under terms of the CBA, the captain will have to report to training camp in September for the team physical. If Drury fails, as would be expected, he would qualify for a long-term injury (LTI) exemption when the season begins and the roster is set.

But in order to gain the full value of the $7.05 million exemption, the Rangers would have to go that far over the cap. In other words, if the cap is $62.5 million (an estimation before it is officially established by June 30), the team would have to get to $69.5 million (including Drury) before the season-opener in Stockholm to reap the full LTI benefit.

Recall that the Rangers never were close enough to the cap at any time last season to be in position to put Vinny Prospal on LTI at the start of the season while he was rehabbing an injured knee or to place Alex Frolov on LTI when he went down with a season-ending knee injury on Jan. 8.

At this stage, it seems implausible the Blueshirts would even approach $69.5 million . . . unless they simply give Brad Richards whatever he wants (if not more!) to sign as a free agent in order to inflate their cap.

Under a buyout, the Rangers would have carried approximately $3.717 million of dead space on the Drury contract through both the summer and the season.

Drury underwent a Feb. 11 arthroscopy that sidelined him for 27 games before he returned on basically one leg for the for the April 9 regular-season finale against the Devils and the playoff first round against the Caps.

But his knee gave out as the series progressed. Coach John Tortorella told the press on breakup day that the captain had a, “chronic knee [condition].”

The Post has learned that conversations between Drury and Glen Sather regarding the possibility that the captain would cite being medically unable to play began when the GM informed him last week of the team’s plans to buy him out.

The initial round of buyouts runs from tomorrow through June 30. There is a second 48-hour window granted in late July or early August following salary arbitration.

Drury, who is owed $5M on the front-loaded, five-year, $35.25 million free-agent deal he signed on July 1, 2007, is expected to undergo a physical in the near future.

If his condition is affirmed, insurance will cover $4 million.

It is not known whether Drury is contemplating major surgery. Regardless, it appears as if Drury’s career has ended after 892 NHL regular-season games in which the Connecticut Kid recorded 615 points (255-360) and 130 playoff contests in which he registered 88 points (47-41).

Drury’s career as a Ranger is ending after 264 games during which he scored 151 points (62-89) and it is ending in a manner that benefits neither the captain nor the club.

larry.brooks@nypost.com

