(CNN) Every November, America remembers the end of Camelot: a shining time of promise led by John F. Kennedy, our nation's youngest elected president, brought to an abrupt and bloody end by Lee Harvey Oswald's second shot, a bullet to the brain.

While conspiracy theorists debate who pulled that trigger, there's another culprit that often goes unmentioned: Kennedy's lifelong struggle with back pain.

It was his habit of wearing a tightly laced back brace that may have kept him from recoiling to the floor of his car after the assassin's first bullet to the neck, setting him up for the kill shot.

"The brace was a firmly bound corset, around his hips and lower back and higher up," said Dr. Thomas Pait, a spinal neurosurgeon who co-authored a paper about Kennedy's failed back surgeries . "He tightly laced it and put a wide Ace bandage around in a figure eight around his trunk. If you think about it, if you have that brace all the way up your chest, above your nipples, and real tight, are you going to be able to bend forward?"

A portrait of pain

The Kennedy clan closely guarded the true extent of John Kennedy's medical problems well past his death.

Though details escaped over the years -- it's hard to hide news photos of him walking on crutches before and after one of his numerous back surgeries -- it wasn't until 2002, when historian Robert Dallek was allowed access to a collection of documents spanning 1955 and 1963, that specifics began to emerge.

John and Jacqueline Kennedy enjoy lunch during their wedding reception in Newport, Rhode Island, on September 12, 1953.

published in September. Pait and his co-author, neurosurgeon Dr. Justin Dowdy, pored over Dallek's subsequent book , numerous other biographies and scores of documents and X-rays at the JFK Library in Boston to prepare their paper,published in September.

"I was taken aback by the depth of Kennedy's pain," Dowdy said. "How long he dealt with pain despite his short life, how it affected his life and how they were able to conceal most of that from the public and certainly from his political adversaries."

Pait agreed: "He was one of our youngest presidents, and he was also one of our sickest presidents. Yet it was important politically for him to keep up the appearance of youthfulness and vigor."

A sickly child -- Kennedy had scarlet fever at age 2 -- he spent his teenage years in and out of hospitals with abdominal and joint pain, flu-like symptoms and extreme weight loss. At the age of 15, Jack (his family nickname) weighed a mere 117 pounds, according to Dallek's research. By the next year, worried he might have leukemia, doctors began regularly checking his blood count. After a bout of tests at the Mayo Clinic, his physicians delivered a different diagnosis: peptic ulcer disease, or what we now call colitis.

John F. Kennedy at age 16, when he played football for the Choate School in Wallingford, Connecticut, 1933.

"God what a beating I'm taking. I've lost 8 lbs. And still going down," Kennedy wrote a classmate , according to Dallek, during the summer of 1934, while tests were underway. "Yesterday I went through the most harassing experience of my life ... an iron tube 12 inches long and 1 inch in diameter up my ass. ... My poor bedraggled rectum is looking at me very reproachfully these days."

Despite a diet of bland foods, nearly constant doctor visits and strong medications, including steroids placed just under the skin to dissolve, his college years at Harvard were plagued by abdominal pain, weight loss and weakness. He began to joke about dying. "Took a peak at my chart yesterday and could see that they were mentally measuring me for a coffin," he wrote a friend

Harvard was also the origin of a new ailment: chronic back pain. It started when he was tackled from the side during a football game, possibly damaging a spinal disc. He began regularly using a corset brace to stabilize his spine and control his discomfort.

"He was blindsided by that tackle, never knew it was coming," Pait said. "He had horrible back pain from it."

The cost of war

Emaciated, with severe back pain and numerous health issues, JFK needed his father's support to get into the Navy during WWII.

After college, it was that back pain, along with his extensive history of other medical problems, that kept Kennedy from his next dream: serving his country in World War II. First the Army and then the Navy turned him down. But Kennedy didn't give up, and with the help of his father's political contacts, he was accepted into the Navy in 1941.

"He made it through the Navy Officer Candidate School in 1941 and then failed his physical again," Pait said. "And then the PT, or Patrol Torpedo, boat experiment began. Again, determined to do more than sit at a desk, Jack pulled more strings. He got into the PT boat training program despite all of his medical problems and his back pain."

Which makes what happened next all the more amazing. According to the JFK Presidential Library , Kennedy's PT-109 was struck by a Japanese destroyer in the inky darkness of August 1, 1943. The impact ripped off the right rear of the boat, tossing most of Kennedy's men into the Pacific Ocean. To get to the closest island, he and his crew swam 3½ miles, with Kennedy towing one of the injured men by a life-vest strap held in his teeth.

"Kennedy was a strong swimmer. The ocean was always part of the whole Kennedy environment, so he grew up in the water as a kid," Pait said. "He called upon his reserves and towed that wounded crewman. It was incredible."

Later that night, Kennedy swam out into the passage, treading water for an hour while he scanned in vain for other PT boats. Over the next few days, he and his men continued to swim from island to island, Kennedy again towing one crewman by his teeth, until they were finally rescued.

Kennedy's bravery earned him the Navy and Marine Corps Medal, and for his injuries, he was awarded a Purple Heart. His heroism also worsened his back injury, securing him a lifelong struggle with back pain.

"After coming back to the states, Kennedy is in a lot of pain; activities are declining; what does this guy do?" Pait asked. "You do what anybody does today. If you have a decline of mobility, you have intractable pain, you look for a solution."

A botched diagnosis?

Doctors continued to fight about the real cause of Kennedy's chronic back pain and the best way to treat it. Part of the problem was the tests used at the time.

"Back then, doctors would stick a needle in the back and inject a dye, air or gas to get pictures of the bones and the spaces between them," Pait explained, a procedure called a myelogram. "Dye was the best, but it was permanent. It would not be absorbed by the body and could cause some serious problems."

Fearful of the consequences of leaving dye behind in their famous patient, Kennedy's doctors chose air as the agent for their evaluation. Unfortunately, Pait said, it did not provide a definitive look at the true problem.

The Wilson plate used in JFK's second surgery to fuse his spine. It was removed months later.

"If Jack Kennedy was treated today, we would have better imaging, with MRIs and higher-field magnets and CT scans," he explained. "We would have a much better image of his underlying pathology and would know whether surgery was the best option."

Kennedy had his sights set on a career in politics. With conservative treatment failing and unable to live with the pain, he made a decision. Against the advice of his doctors at Mayo, he underwent spinal surgery in June 1944, at New England Baptist Hospital.

"Unfortunately, it didn't go well," Pait said. "About six weeks after the first operation, the pain returned, and he was in terrible shape, just awful shape. And with that first failed surgery, his continued campaign against pain was now underway for the rest of his life."

Pait and Dowdy examined Kennedy's pre- and post-surgical X-rays. Their analysis, made from the viewpoint of spinal surgeons, found no abnormalities in the spaces between vertebrae and no sign of underlying bone disease, which had long been suspected due to Kennedy's use of steroids.

"Long-term steroid use can cause bone disease," Pait said, "but we did not see that the steroids had been used to the extent that the bone gave way. He did not have evidence of that sort of fracture, in my opinion."

Would he have gotten better without surgery?

"We all have back pain, and most of us get better and don't need surgery," Pait said. "Would he have fallen into that category? It's tough to say. Back pain is very complex and a tough thing to treat. I think he would have eventually found himself in an operation, as he did, because he had dreams and didn't like this painful enemy he was dealing with."

Kennedy expressed his own disappointment in the outcome: "I think the doc should have read just one more book before picking up the saw." Yet, despite that opinion, he would go under the knife twice more in a desperate bid for pain relief.

The path to 'Dr. Feelgood'

Kennedy's next surgery, in October 1954, nearly killed him. After a metal plate was inserted in his lower back to fuse his spine, he developed a urinary tract infection. He got so sick, the family called a priest to administer last rites. This would be the second time; a priest had also been called in 1947 after Kennedy was diagnosed with Addison's disease, an adrenal gland disorder causing fatigue, muscle weakness, weight loss and abdominal pain, reminiscent of his childhood illnesses.

John F. Kennedy and wife Jackie leaving the hospital two months after his 1954 spinal fusion.

Addison's compounded his surgical risk, yet despite the dangers, Kennedy again insisted on the surgery. By this time, he was in the Senate and using crutches almost constantly to travel back and forth for roll calls and official business. His mother, Rose Kennedy, wrote in her memoirs, "Jack was determined to have the operation. He told his father that even if the risks were fifty-fifty, he would rather be dead than spend the rest of his life hobbling on crutches and paralyzed by pain."

Unfortunately, Kennedy never fully recovered from the fusion surgery, developing a staph infection that created an "open, gaping, very sickly looking hole," according to Ted Sorenson, Kennedy's speechwriter. By February of the next year, he was back in the hospital, undergoing surgery to remove the plate; it would be May before he could return to the Senate.

"He was not unlike many Americans who suffer from chronic back pain, in search of solutions to resolve their pain so they can carry on with their lives," Pait said. "It's one reason we have a national crisis in opioids and narcotics: people wanting a solution to their pain."

In fact, Kennedy's next solution was to turn to muscular injections of procaine, a version of lidocaine, a numbing agent that blocks nerve signals to the brain. According to Pait and Dowdy, he would receive "hundreds, if not thousands," of injections over the next four years, which along with muscle strengthening and use of the corset produced "dramatic" improvement in his back pain.

But the grueling campaign leading up to his election as president in 1960 again took a toll on Kennedy, and he would find relief in the hands of Dr. Max Jacobson, who had the nicknames "Miracle Max" and "Dr. Feelgood" for injecting his patients with amphetamine-based concoctions.

"The secret formula was thought to have some methamphetamine in it," Pait said. "He injected Kennedy, and it made the president feel fantastic. He was high. And he was not in pain."

Kennedy was said to have gotten an injection from "Dr. Feelgood" just before his famous debate with Richard Nixon and three such injections on the first day of the Vienna summit with Soviet Premier Nikita Khrushchev, which did not go well for Kennedy.

"Kennedy told the press after the summit that Khrushchev 'just beat the hell out of me,' " Pait said. "Later, his brother Bobby confronted Jack about the shots, and Jack said, 'I don't give a damn if it's horse piss, it makes me feel better.' People say that today with the opioid epidemic: 'I don't give a damn what you say, I need my medicine!'

A new beginning

In Dallas, "Kennedy wanted to sit up high and wave at people."

By the end of 1961, concern was so high about the president's use of injections that Rear Adm. George Burkley, who had been White House physician since Eisenhower, took over Kennedy's care.

He brought in a new doctor, Dr. Hans Kraus, known today as the father of sports medicine, who established a multidisciplinary pain center in the late 1950s. It was Kraus' belief that much of back pain originated in weak and deficient muscles.

Kraus put Kennedy on a regimen of weight-lifting, swimming, massage and heat therapy, and began trying to wean the president off the back brace.

"Kraus felt that the brace was getting in the way of Kennedy's strengthening exercises," Pait explained. "For example, today we tell people not to sleep in the brace. We try to get people out of the brace as soon as possible because it makes the muscles lazy.

"Now, by this point, Kennedy had been wearing the brace most of his adult life," he said. "For JFK, his brace was like Linus' blanket, the Peanuts character. Kennedy had to have this brace. It made him sit up straight and gave him pain relief."

Kennedy rides through Dallas on November 22, 1963.

Almost immediately, the new approach had "dramatic" benefits, Pait said, and Kennedy was well on his way to recovery from back pain, perhaps for the first time in his life. Then, in August 1963, just a few months before the visit to Dallas, Kennedy strained his back and began relying on the brace again, despite his doctor's concerns.

"Kennedy said to Kraus, 'Look, I tell you what, when I come back from Dallas, I'll get out of the brace, but I gotta wear it for this trip. I gotta look good.' He wanted to be able to sit up tall and wave at people," Pait explained.

"And of course, we'll never know if he would have survived if he'd followed the doctor's advice and gotten rid of it."