No golfer likes it when a shot lands in a sand trap, but Jeff Robinson used to get particularly distraught when it happened. Having struggled with sore knees for two decades, just navigating the small descent into a bunker was excruciating.

"I couldn't go downhill without pain," he said. "By the end of the round, my knees would be totally inflamed."

The 63-year-old Minneapolis real estate agent still lands in the occasional sand trap, but it no longer bothers him -- at least not on a physical level. After trying everything from arthroscopic surgery to cortisone shots to lubricant injections, he finally opted to have both knees replaced, the left one in December 2007 and the right one three months later. His knee replacements "worked out so well that now I'm encouraging everyone who has problems to do it as soon as the problems start to impede their ability to do things normally," he said.

The knee is one of the body's most complex joints. It's also one of its most used joints. That combination increases the odds of something going wrong. The possibilities are extensive, from meniscal tears to ACL strains, from muscle contusions to bone fractures, from bursitis to arthritis.

"It's basically three joints in one," said Dr. Richard Kyle, chair of orthopedic surgery at Hennepin County Medical Center. The knee has to flex, extend and rotate. "It's a complex joint with a complex ligament structure to support it."

Knees get a lot of attention in the sports pages, where injuries have sidelined such stars as Vikings running back Adrian Peterson and Timberwolves guard Ricky Rubio. But it's not just pro athletes who battle knee problems. Recreational athletes are laid up by bum knees, too, an occurrence becoming more common as baby boomers continue to be physically active much later in life than previous generations.

"It's become the No. 1 soft-tissue sports injury," Kyle said. "The sheer number of recreational athletes -- the weekend warriors -- has a lot to do with that volume. The baby boomers are remaining incredibly active."

Gender equality also is a factor, he said. It used to be just men who complained about the stereotypical "old sports injury." With the explosive growth in girls' athletics, that's no longer the case.

"A generation ago, you didn't have girls playing hockey or girls playing rugby," Kyle said. "Now they're involved in all sports."

In praise of knees

Some people who face chronic problems grumble that knees are the weak link in the chain. Doctors disagree. "The knee is actually very strong," said Dr. Ed Laskowski, co-director of the Mayo Clinic's Sports Medicine Center. "It can handle most physical extremes. We're all playing sports at a higher level than we used to. We're bigger, faster and stronger. All things considered, it's a very strong and stable joint."

But that strength and stability can disappear in a painful flash if we abuse it, a situation covering everything from taking a nasty fall when skiing, to using improper form while running, to overuse issues, including the strain of obesity. The good news is that all of those things are preventable, at least to an extent.

"Prevention is a huge, huge, huge part of what we do," Kyle said.

You can even take steps to reduce falling. Balance and movement exercise like tai chi can help prevent falls, especially as we age. Muscle fatigue and poor conditioning also can play a role in knee injuries.

"I don't know how many times I've had skiers tell me that they were hurt on what was going to be their last run of the day," Laskowski said. "It's muscle fatigue. At the end of a weeklong ski vacation, the muscles surrounding the knee can tire, and this can increase your injury risk."

Conditioning is a key element in knee health, doctors insist. "If you want to play a sport in which you have to jump, cut and pivot and change directions fast, that's fine," Laskowski said. "But first make sure the tissues [in your knees] are prepared for that."

He highlighted four areas of focus: flexibility, strength, aerobic condition and stability/balance. "You should prepare for the specific demands and movement patterns of the sport you're going to do," he said.

Tune up your technique

Bad form is another knee killer, especially for distance runners. Sometimes the problem can be solved with orthotic inserts or different shoes. Sports medicine therapists also can analyze your gait and alignment and recommend specific exercises to help reduce the risk of overuse injuries.

"Technique is one of the keys" to avoiding wear-and-tear injuries, Laskowksi said. "You want the mechanics of the movement to be as good as they can be."

Another cause of overuse injuries is insufficient rest. Jogging 10 miles every day might impress the folks in your running club, but if you could ask your knees, they'd probably have a different opinion.

"Cross-training is one of the best ways to avoid knee injuries," Kyle said. "Muscles will regenerate; cartilage will not. You have to give cartilage a chance to rest. Instead of running every day, bike or swim. And whatever you do, do it in moderation. Give the tissues time to heal."

Last-resort option

Some knee problems are unavoidable. Sports injuries are a case in point, something Howard Liszt knows well. The journalism professor at the University of Minnesota was a 20-year-old second baseman when he went to turn what should have been a routine double play. But when he stepped on the bag, his spikes got caught and his right knee twisted.

"I recovered at first, but it set off a whole series of injuries until it got to the point it was bone-on-bone," the 65-year-old said. Five years ago, he decided to have the knee replaced "because there was nothing else that could be done."

Robinson and Liszt are typical knee patients in that their doctors tried other approaches before surgery. Some injuries -- a torn ACL, for instance -- leave doctors no choice but to operate, but for other problems, it's the remedy of last resort. "Before we operate, we try to do everything we can to treat them," Kyle said.

Robinson and Liszt also are typical in that they resumed their full activities once they healed. The notion that a repaired knee has to be babied for the rest of one's life is long gone, doctors said. On the contrary; factor in the lack of pain that was restricting movement before, and the activity level increases for most people.

"It's great," Liszt said. "I'm playing tennis again, and I don't have any pain when I move. I'm clearly much more active."

Jeff Strickler • 612-673-7392