Editor's Note: Phil Mickelson and Jim "Bones" Mackay that they’ll part ways as player-caddie, after a successful 25-year tenure that included 41 PGA TOUR wins and five major titles.

The way Jim Mackay saw it, he had no choice.

Day after day, he’d walk the requisite five or six or even seven miles, Phil Mickelson’s 40-pound golf bag draped across his shoulders. Every hill and valley added to the strain on his knees. Ditto for the occasionally soggy turf.

“It got to the point where at the end of the day … I had to pick my legs up and put them in the car because I couldn’t do it the normal way,” Mackay said.

The lanky 51-year-old, who is known to everyone in the game as Bones, hadn’t been able to run for at least 10 years. Playing ball with his kids on a week off was out of the question. The aching in his knees was “crazy painful,” and Mackay knew something had to be done.

“It not only hurt when I worked, but it hurt in the middle of the night when you walked 40 feet across your bedroom,” he said. That is, when he was able to get to sleep.

A year ago this week, Mackay basically reached his breaking point.

Mickelson was leading the AT&T Pebble Beach Pro-Am heading into the final round. Sunday morning, minutes before the team was scheduled to tee off, the four-time champ decided on an equipment change. So he asked his caddie to go to the car and get the new club.

“I ran from here to that tree,” Mackay said, gesturing about 30 yards away. “I remember thinking to myself, I have to have surgery. I thought my legs were going to fall off.

“At that point it was like, this is ridiculous.”

Mackay made it through the rest of the season, as well as the 2016-17 PGA TOUR opener at the Safeway Open. The following Wednesday in what Mackay calls a total coincidence, he was on the operating table – at the exact same time Mickelson was having the first of two sports hernia surgeries.

“Phil called (my) doctor the day before the surgery and he goes, hey, man, I need your best tomorrow,” Mackay said, chuckling. The three are members at Whisper Rock Golf Club, along with several dozen other TOUR pros..

Four hours later, Mackay had a new pair of titanium knees and a matching set of 6-inch scars over each kneecap. He was walking the next day, aided by a walker for several weeks and then switching to a cane.

“Once you stop limping, they want you to kind of go it alone,” Mackay said. “They found out during the surgery that not only were my legs beaten up from what I do for a living, but genetically they were really bad to begin with.

“So that made us doubly glad that we did it because it was kind of an accident waiting to happen.”

Mickelson and Mackay have been a team since the 1992 U.S. Open, the longest-running partnership on the PGA TOUR.  The two teamed up at the 36-hole qualifier, where Mickelson broke the course record, and have never looked back.

“That was the first day I'd ever seen him play because he didn't play a practice round,” Mackay recalled. “He won the NCAA the week before by a bunch and showed up, did that.  So, it was cool.”

Mackay has been on the bag for all but one of Mickelson’s 42 victories, including all five major championships.

Seven-and-a-half weeks after the double replacement, Mackay was back on the course, playing golf with friends. Although he was already walking several miles at a time, he took full advantage of the handicap rules.

“You get one of those little blue flags where you can drive on the fairway, so that was big for me because everybody else was cart path only, so I loved that,” Mackay said, grinning.

Mackay and his boss eventually returned to the TOUR, slightly ahead of schedule, three weeks ago at the CareerBuilder Challenge. Three rounds with amateurs might have been a blessing for Mackay, who had not carried a bag for 18 holes since Napa.

“That slows things down,” Mackay said. “And I’m not setting any speed records right now.”

Without the knee replacements, Mackay says he doubts he could have  caddied a full season because the damage was worse than the doctors had expected.

“I was headed for something bad,” said Mackay, who winds down after a round with massaging leg sleeves.

This week’s AT&T Pebble Beach National Pro-Am is Mackay’s fourth event in a row, which is a challenge even under the best of circumstances. But he feels fitter than he expected and the doctors say his legs will continue to grow into the new knees for nine months to a year.

“it doesn't hurt as bad as it did last year, so I'm ahead in the game, and it's only going to get better.” Mackay said.

Beyond The Ropes is PGA TOUR Digital’s new weekly column focusing on lifestyle stories and features in the world of golf. If you have a story suggestion, please email Helen Ross at helenross@pgatourmail.com