FLORHAM PARK, N.J. -- Vinny Testaverde was present for arguably the most significant Achilles injuries among quarterbacks in NFL history. Talk about an eerie coincidence.

In 1993, he was on the opposite sideline when Miami Dolphins legend Dan Marino ruptured his Achilles against the Cleveland Browns. In 1999, Testaverde was the one injured, crumpling to the ground as he attempted to pick up a fumble for the New York Jets -- a noncontact injury.

Then for the Jets in the season opener Sept. 11, the former quarterback for seven NFL teams was in the owners box as Aaron Rodgers went down with a left Achilles tear on the fourth play of the season -- a crushing injury that transcended sports because of Rodgers' star power.

Testaverde's heart sank, knowing what was ahead for Rodgers. His mind raced back to '99 and the long, grueling days of rehab -- days that produced pain and doubt. He made it back to his previous form, but only after months of wondering if he'd ever be the same.

"When I first got back to being able to do football activities, in the back of my mind there was always a fear of it snapping or popping again," Testaverde said in a phone interview. "I was just fearful that it would happen. I wasn't as confident as a player might be today because of the different techniques and the way it can heal better."

A torn or ruptured Achilles is a very challenging injury for a professional athlete, mainly because the rehab can last up to a year. It can be unpredictable, with setbacks and prolonged plateaus. Describing the rehab, Testaverde said it's like hair growing on your head: You know it's occurring, but you can't see it.

Rodgers, who underwent surgery Sept. 13 in Los Angeles, reiterated to NBC Sports on Sunday night that his goal is to play again this year.

It's rare for an NFL quarterback to have an Achilles tear. Marino, Testaverde and Rodgers are believed to be the only NFL quarterbacks in recent history to have suffered the injury, according to ESPN injury expert Stephania Bell. Going way back, it happened to Johnny Unitas (1971) in the twilight of his career. Both Marino and Testaverde returned for several seasons, but Marino was 32 when he got hurt. Testaverde was 35.

Rodgers turns 40 in December, creating a unique situation, according to Bell. Rodgers is an elite NFL quarterback who is benefiting from advances in surgery and rehab that didn't exist when Testaverde was injured in 1999.

Rodgers' surgery was performed by orthopedist Neal ElAttrache, who has operated on numerous athletes, including repairing the late Kobe Bryant's Achilles in 2013 at age 34. For Rodgers, ElAttrache used a minimally invasive SpeedBridge repair, a technique that was developed about a decade ago.

This method is referred to as minimally invasive because the incisions are small which promotes rapid wound healing and decreases the risk of infection. The ruptured tendon is repaired and reinforced with synthetic sutures called SutureTape. The SutureTape is then secured down into the calcaneus, or heel bone, with two Arthrex SwiveLock anchors. This construct positions the Achilles with the appropriate tension and improves overall stability, allowing for early post-operative weightbearing and range of motion.

Typically, it takes three to four months for the tendon to heal completely, Bell said, at which time Rodgers will be able to ramp up his rehab.

WHEN HE HEARD Rodgers' diagnosis, Jets defensive end Carl Lawson decided a return-the-favor phone call was in order.

Lawson ruptured his own Achilles in August 2021 while pass-rushing Rodgers in a joint practice with the Green Bay Packers. Over the next year or so, long before they became teammates, Lawson received occasional words of encouragement from Rodgers.

So on the night of Sept. 11, after the Jets' overtime win over the Buffalo Bills, Lawson made it a point to call his quarterback. He wanted to boost Rodgers "in his dark time," as Lawson called it.

"You could hear a damaged spirit," Lawson said, recalling the conversation, "but not a broken one."

Lawson knows the journey of an Achilles patient better than anyone on the current Jets -- the highs and the lows. Lawson had a setback in his rehab, requiring a second surgery in January 2022. He made it back for training camp six months later, but it wasn't easy.

"I had a really hard recovery," Lawson said.

Lawson said his surgeon didn't use the SpeedBridge technique for his Achilles. He declined to specify what went wrong in his rehab, except to say the setback sent him "back to square one."

"It's also a body-weight thing and explosion thing," said the 265-pound Lawson. "Not saying [Rodgers] isn't an explosive athlete, but he's a quarterback. So I think his transition from the Achilles will be much smoother than mine was."

The "silver lining," according to Testaverde, is that Rodgers injured his left Achilles.

"The good thing is, it's not on his plant foot -- his back foot," said Testaverde, also a right-handed passer who hurt his left foot.

"He'll be able to drop back on his healthy leg, stick that right foot in the ground and push forward to step up into the pocket. If he's going to have a speedy recovery, that's going to help him tremendously to get back to feeling confident and playing."

Concerned about his mechanics, Testaverde videotaped his post-injury throwing sessions to make sure he wasn't compensating in any way. The videos were evaluated by the Jets' coaches.

Testaverde underwent surgery the same day as his injury, rehabbed at the Jets' facility for the remainder of the season and finished up at his home in Tampa, Florida, where he owned a 1,500-square-foot gym. In a 2000 interview with the New York Daily News, he said, "Some days, I'd be in here screaming. Other days, I felt like crying. It was that scary. It was the fear factor, not knowing what was happening."

In the back of his mind, Testaverde thought about Marino, whose mobility -- never a strength -- was further compromised by the injury. Marino himself acknowledged it wasn't a clean recovery, recently telling Kevin Clark on his "This Is Football" podcast, "From what I remember, it didn't actually heal all the way. [The tendon] was elongated, so I had to be able to deal with not getting up on my toe for the rest of my career, basically."

That weighed on Testaverde.

"I was always a little tentative and nervous going forward because of Dan Marino's injury," he said.

Basically, Marino's tendon got stretched. Maintaining tension of the repaired tendon is critical to a successful outcome, according to Bell, because the Achilles is about elasticity.

Post-surgery, Testaverde started every game for the next two seasons, leading the Jets to a playoff berth in 2001. He doesn't believe the Achilles affected his overall performance, though he admitted he lost some muscle and explosiveness in his lower left leg. Testaverde would play in the NFL until 2007, when he started six games for the Carolina Panthers at the age of 44.

During his prime, Rodgers was one of the most mobile quarterbacks -- he rushed for a career-high 369 yards in 2016 -- but his production has tailed off in recent years. Testaverde suspects the injury might limit Rodgers in some ways, but he doesn't foresee a significant drop-off.

"His ability to throw the football is superior to just about everybody in the league. He's not going to lose that," Testaverde said. "Will he get sacked one or two more times next year? Maybe, because he can't avoid a sack or two. It's hard to predict. I just think he's going to do well. He's motivated. It sounds like he wants to come back and play again, which is good for all Jets fans to hear."

IN HIS FIRST interview after surgery, an appearance on "The Pat McAfee Show," Rodgers said his medical team had formulated a "pretty damn good rehab plan that's going to, I think, shock some people."

It includes the use of a hyperbaric chamber, an oxygen-rich environment that promotes healing. Lawson said he had positive results from a hyperbaric chamber after his second surgery.

Rodgers' doctor, ElAttrache, also believes in early post-operative use of a rehabilitation technique called blood flow restriction (BFR), which has been widely used in the military for blast-trauma victims.

A tourniquet -- similar to a blood-pressure cuff -- is applied near the injured area, which partially restricts the flow of blood during strength training. This facilitates muscle gains and limits atrophy, according to Johnny Owens, who developed the application within the military population several years ago. He then developed clinical applications for elite athletes undergoing load-protected rehabilitation. Former Houston Texans pass-rusher Jadeveon Clowney was the first NFL player to use BFR (for an injured knee), and now every team utilizes it.

"Now we can get it on [Rodgers] fast ... and just stop that calf muscle and thigh muscle from atrophying away," said Owens, a physical therapist and chief of human performance optimization at the Center for the Intrepid at the Brooke Army Medical Center in San Antonio, Texas.

With an Achilles injury, the patient applies the tourniquet to the upper thigh and performs light exercise. Typically, under ElAttrache, Achilles patients start this process within a few weeks after surgery, according to Owens. The SpeedBridge surgery, coupled with BFR, is "a game-changer" that will allow Rodgers to be more aggressive in his rehab, Owens said.

Everybody wants to know when Rodgers, who is rehabbing at a facility near his home in Malibu, California, will be able to play football again.

For his part, Rodgers said he doesn't have a specific timeline, saying he wants to get healthy "physically and mentally ... and do everything I can rehab-wise to put myself in a position to be ready to play football again at some point."

A typical recovery takes about nine months, although Minnesota Vikings running back Cam Akers made it back in five months in 2021 when he was with the Los Angeles Rams. There are three primary phases to recovery, according to Bell: healing of the wound, healing of the tendon (approximately three to four months, during which mobilization/strengthening and restoration of normal gait are the focus), and an aggressive return to sport/return to play rehab.

Rodgers told McAfee he has had "good days and bad days" in his rehab, saying, "Every day, it's just a little something -- a little less swelling, a little more movement, a little mobility, a little more strength. So we're building it up. It's just a process."

His age could be a factor, as tissue tends to get more brittle and less resilient with age, Bell said. There are certainly individual variations and factors such as nutrition and diet that can play a role. The multitude of contributing factors makes it hard to project an exact timeline.

On Sunday night, about two hours before the Jets faced the Chiefs at MetLife Stadium, Rodgers emerged from the tunnel and -- with the use of crutches -- walked briskly down the Jets' sideline. Later, teammates remarked how well he seemed to be getting around, considering he was less than three weeks removed from surgery.

Rodgers rejoined the team late Saturday after receiving medical clearance to fly cross-country, but his plan is to return to California this week to have his stitches removed and to continue rehabbing for five hours a day, he told NBC Sports. He indicated he will rejoin the team permanently after the Week 7 bye.

"He just came into the team room like Batman, honestly," wide receiver Allen Lazard said, referring to Rodgers' appearance Saturday night at the team hotel. "It was just kind of a Hollywood-esque moment of Aaron Rodgers appearing -- walking. I thought he was about to fly, honestly."