Just picture it. You and a couple of your favorite Playboy Playmates are romping around on the bed about to get frisky. You know, your usual Saturday night type of stuff. Suddenly a sharp pain in your knee causes you to scream out. Miss November and Miss July think that you're in ecstasy, but your knee is in agony and this is really ruining a good time.

Okay, back to reality. In real life the situation was probably more like this: You got caught up in a Brady Bunch marathon on cable 'cause, dammit, that Marsha was hot, wasn't she? The problem is, along with other things, your knee has gotten so stiff from sitting that you can't stand up. What's going on here? Well, remember back to your high school football days when you heard a loud "pop" from your knee while you were cutting to the right to make a play? The coach told you to stop being a pussy, but you knew something was wrong even back then.

Knee pain is a common malady for both trained and untrained people. However, just what exactly is causing that pain can be varied, indeed. Whether your knee pain is coming from patellofemoral pain syndrome, ligament sprains or tears, cartilage (meniscal) tears, tendinitis, or just plain old age (arthritis), I'll explain it and tell you how to prevent and rehabilitate it. After reading this article, you'll never have to worry about having your good time (or your next workout) spoiled again.

A Little Anatomy

You must know the anatomy and inner workings of a joint in order to describe the injuries that may occur. Sorry, guys, but I've just got to school you on the basics right now. The knee joint bones consist of the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). The ligaments are the static and primary restraints of the joint. In other words, they provide the stabilization of the joint.

The medial collateral ligament (MCL), which provides restraint against valgus forces [bent or twisted away from the midline] to the knee, originates on the inside of the femur and attaches on the inside of the tibia. The lateral collateral ligament (LCL), which provides restraint to varus forces [the opposite of valgus forces] at the knee, originates on the outside of the femur and attaches to the fibula. Then you've got the anterior cruciate ligament (ACL), the primary restraint to anterior tibial translation on the femur. It attaches from the anterior tibia to the posterior femur deep inside the knee joint.

The posterior cruciate ligament (PCL) limits posterior tibial translation on the femur and attaches from the posterior tibia to the anterior femur. The two ligaments cross inside the knee joint, hence the name cruciate (cross-shaped). The muscles are the dynamic and secondary restraints surrounding the knee joint. The primary muscles are the quadriceps muscles on the front of the thigh, the adductor muscles on the inside of the thigh, the hamstring muscles on the back of the thigh, and the tensor fascia latae and iliotibial band on the outside of the thigh.

There are two types of cartilage inside the knee joint. The first type of cartilage is called hyaline, or articular cartilage, and it's actually present on the ends of all long bones. It's a protective covering that reduces friction and shock. When you ravage a chicken drumstick and eat every last piece of flesh, you'll notice a bluish-white shiny substance at the end of the bone. This is the same articular cartilage that you'd find in your knee.

The second type of cartilage is called fibrocartilage or meniscus. There's a medial and lateral meniscus that rests on the top of the tibia. The functions of the menisci are to provide shock absorption, enhance knee stability, transmit weightbearing forces, and assist with joint lubrication and nutrition (and you thought that was your girlfriend's job!)

The Patella

The patella (kneecap) is a special and very important bone in the knee. The patella and the femur form the patellofemoral joint (PF). The patella is located inside the tendon of the rectus femoris muscle, which connects the femur to the tibia. The femur has a concavity or groove where the patella rides up during extension (knee straightening), and down during flexion (knee bending).

The underside of the patella has many ridges that are covered with hyaline cartilage. When the cartilage is healthy and the ridges fit into the femur well, the knee is pain-free. However, if the patella and femur don't mesh well together, the cartilage can wear down and it could predispose a person to PF pain. The patella's true function is to give the quadriceps muscles increased efficiency and to protect the front of the femur.

Knee Biomechanics

Now that we've snoozed through a review of anatomy, let's all take a nap during the biomechanics section. No, just kidding, guys! If you understand how the joint works and what kinds of forces it may be susceptible to during daily activities and exercises, you'll know what's effective and what's harmful.

The patellofemoral joint reaction (PFJR) force is the result of the amount of knee flexion and the force of the quadriceps muscles creating pressure on the patella against the femur . As the knee flexes and the foot is in contact with the floor, the patella is mostly in contact with the femoral groove . This large amount of contact area can help dissipate compressive forces. However, as the knee extends and the foot is off the floor, the patella has minimal contact with the groove. This small contact area can't disperse compressive forces well.

When applying this concept to exercise, large compressive forces can be seen when performing a seated knee extension as the quadriceps have to generate great force to overcome gravity and lift weight. When the knee flexes while squatting, the PFJR force increases, but the load is more evenly distributed across the patella, which is coming into contact with the femur.

Patellofemoral Pain Syndrome (PFPS)

The previous discussion of biomechanics (you didn't sleep through it, right?) leads us to one reason why people may have knee pain. The symptoms of this syndrome are crepitus (the "Rice Krispy" noises the knee makes – you know, the "snap, crackle, pop") and pain with prolonged sitting, squatting, and walking up and down stairs.

I've heard plenty of patients in my clinical practice complain about knee pain, yet insist that the leg extension machine is the best thing since Viagra. The truth is, many theories have been proposed to describe why and how people experience PF pain, but it's still a subject of debate. One popular theory blames PF pain on abnormal patellar movement. This faulty movement pattern increases the stress between the patella and the femur and wears out the cartilage on the underside of the patella. Although the cartilage itself has no pain receptors, the bone underneath does.

When the cartilage is healthy and the ridges fit into the femur well, the knee is pain-free. However, if the patella and femur don't mesh well together, the cartilage can wear down and it could predispose a person to PF pain and eventually arthritis. But the "why" question of PF dysfunction is really an individualized issue and based on a person-to-person basis. In some cases, a congenital malalignment of the lower body may be the culprit. In this case, orthotics may solve the problem. Tight and/or weak musculature, muscular imbalances, lax ligaments, overuse, improper exercise equipment, or trauma may also be to blame.

Treatment

If you think you have PFPS, treat the symptoms with rest and ice and visit an orthopedic surgeon who specializes in sports medicine. The surgeon can accurately diagnose you and help to determine the cause of the pain. Strengthening and flexibility of the entire lower extremity from the hip to the foot is important. When the entire quadriceps group is strengthened, it may help change the contact areas between the patella and femur and redistribute the pressures . This in turn can relieve painful areas of worn cartilage.

Certainly, staying away from the leg extension machine, which is about as functional as a gasoline-powered vibrator, is a good idea. Exercises that are safe and effective include: backward walking/running, backward stair climbing (slowly, emphasizing knee extension and quad contraction), lateral step ups/downs, and bicycling with the seat high and resistance low. In addition, during rehabilitation, leg presses and squats should be kept in the range of 0^o to 30^o and knee extensions only from 90^o to 60^o to decrease the PFJR forces.

However, the rule of thumb is that all exercises be performed pain-free. If more range of motion can be obtained in the leg press or squat pain-free, the best quadriceps strengthening can be found from 88^o to 102^o. If working with a rehabilitation professional, they may recommend bracing and taping to decrease the pain so the joint can be strengthened. Braces and taping may also improve patellar tracking by positioning the patella better in the femoral groove.

Orthotics for the feet may be indicated to correct malalignments. Surgery in the form of an arthroscopic debridement or drilling of the patella and femur, a lateral retinaculum release, realignment of the extensor mechanism, patellectomy (removal of the patella), or total knee replacement are all last resort options.

Ligament Injuries

You hear about it almost everyday during football season. The star player, probably on your team, tears his ACL and is out for the season. "That guy's a pussy, not a player!" you say to your buddies during a night of cold beers, ESPN, and blow-up dolls. Of course, being the safe, couch-potato spectator doesn't make you an expert, but you do know that if it happened to you, you wouldn't have to sit the season out collecting a paycheck for being hurt. You are a man and would whip right back into shape immediately!

As much as I hate to admit it though, ligament injuries really do require some time spent on the bench. The severity of the injury will tell just how much time. You can sprain or tear any of the four main knee ligaments (MCL, LCL, ACL, PCL), although the incidence of MCL and ACL sprains/tears is the highest. Sprains are graded by manual examination and assigned a number to correlate with their severity.

A Grade I sprain involves none to slight laxity; a Grade II sprain involves slight to moderate laxity; and a Grade III sprain involves moderate to full laxity (complete tear). Typically, Grade I sprains require some rest and minimal rehabilitation, while Grade II and III sprains may require a long convalescence (four to six weeks for healing), extensive rehab, and possibly surgery.

In order to sprain or tear your MCL, a force needs to be directed from the outside of the knee joint pushing inward. Picture a linebacker diving at the outside knee of a running back. The force from the outside makes the inside of the joint gap – a valgus sprain. MCL sprains can also happen with bodyweight force. For instance, if you twist forcefully on a planted foot, you could easily damage the MCL.

The MCL is a thick ligament that has a relatively good blood supply. This means that it heals very well and rarely requires surgical intervention. Therapy for a sprained MCL would start with modalities to decrease pain and swelling, rest and immobilization depending on the severity, initiation of range of motion (ROM) when indicated, and strengthening of all the leg and hip musculature, especially the adductors.

Sprains and/or tears of the LCL aren't common because of the mechanism of injury needed for this trauma. A LCL injury involves a force directed at the inside of the knee and pushing out. Of course it could happen, but it's tough to hit that position. Therapy for LCL sprains follows the protocol for MCL sprains, except strengthening would concentrate on the abductor muscles.

The PCL is an extremely difficult ligament to sprain and/or tear because it's so strong. As a matter of fact, it is the strongest ligament in the knee. The most common mechanisms of isolated PCL injuries are a fall on a bended knee or a direct blow to the front of the knee with the force directed posteriorly . In addition, the PCL can be injured in a car accident if the tibia hits the dashboard. Usually, isolated PCL sprains are treated conservatively with rehabilitation. Surgery may be indicated if the PCL is completely torn and other structures are damaged too. Rehab first focuses on decreasing swelling and increasing ROM and then on increasing quadriceps strength and hamstring flexibility.

The ACL is the crucial structure for knee joint stability, especially for athletes in sports that involve running, jumping, and pivoting. The most common mechanisms of ACL injuries are the non-contact movements of planting the foot and twisting, hyperextending the knee, or decelerating from a run or a jump. An ACL tear can result in serious damage to other joint structures and take months to heal after surgical reconstruction. But having an ACL tear doesn't mean the end of athletic participation, as we've all seen.

ACL reconstruction surgery and rehabilitation is getting so accurate and sophisticated, that now it's the rare athlete who doesn't return to his previous level of activity. After the acute injury, the rehabilitation involves special attention to exercises designed to increase muscular strength and overall stabilization, to increase muscular endurance, to increase reaction time, and to teach balance, coordination, and proprioception. Hamstring strengthening should play a major role in ACL injury prevention and rehab.

Meniscal Tears

Does your knee lock when you bend down to grab a weight off the floor? Do you have pain or clicking on either side of your knee, behind your patella? If so, you may have a meniscal tear. The medial meniscus is by far more commonly torn because of its close association with the MCL and its firm attachment. The common mechanism for a medial meniscus tear is weight bearing combined with a rotary force while extending or flexing the knee.

I once consulted a bodybuilder who refused to believe that he tore his medial meniscus from his poor squatting form. When I observed his squat, I noticed that he did no warm-up sets, loaded up the bar with weight too heavy for his disproportionately small legs, reached rock bottom but had to lift his heels and bounce out to get back up, and rotated his knees inward during the ascent. Hello, meniscus tear! He was essentially grinding his meniscus between his femur and his tibia and he expected it to hold up forever. A rocket scientist this guy wasn't.

Cutting quickly while running can also tear the medial meniscus. Lateral meniscus tears are more infrequent and involve forceful knee extension and external rotation.

So what's a guy to do about meniscal tears? Well, some tears are non-symptomatic or only act up once in awhile. Of course, surgery is an option for symptomatic tears. Surgeons used to take the whole meniscus out during an open procedure, but now they can cut out the part of the meniscus that's torn, during an arthroscopic surgery. Because it's much less invasive and drastic, after an arthroscopic meniscectomy the patient can resume high-level sports in as soon as a month.

Surgeons can even repair a torn medial meniscus if the tear is in an especially vascular area. The patient will be left with an intact meniscus after some precautions are taken during the rehabilitation. This would be the best-case scenario since removing a part or the whole meniscus leads to osteoarthritis in later years.

Tendinitis

Tendinitis is an inflammation of a tendon. A tendon is the tough tissue at the end of a muscle that attaches that muscle to the bone. In the knee, the patellar tendon, which connects the rectus femoris muscle (largest quad muscle) to the tibia, can be the source of pain. I heard a funny story about an Olympic weightlifter who got a terrible case of patellar tendinitis by trying to be the best athlete he could, but unfortunately, this guy couldn't even place in a Mental Olympics.

The story goes that while training in America, this athlete heard that the Russians were doing plyometric depth jumps from six feet high. Believing it to be true, this 300-pound monster built a seven foot high platform for his depth jump training. "If those Russian bastards can do it from six feet," he must have thought to himself, "I sure as hell can do it from seven!"

Just to give you a little background on the subject of depth jumps, which is considered an advanced plyometric drill, the athlete stands on a platform, jumps up and off, lands, and immediately jumps up again. Usually athletes will start training at a height of one to two feet. Well, this mental titan, who, by the way, had never done depth jumps, jumped down from seven feet. With his 300 pounds accelerating towards the ground, the guy didn't even have a chance to jump back up. It's truly amazing that his tendons didn't rupture and his knees explode all over the floor. But, he did get a nasty case of patellar tendinitis that took him out of competition for weeks.

With this warning, I'm sure this will never happen to you. Besides jumping, tendinitis can also occur from running, kicking, or any repetitive motion. The treatment is always rest, ice, and anti-inflammatories until the pain and swelling dissipate. Quadricep stretching is indicated, as well as cross-friction massage over the tendon (vigorously rubbing the tendon perpendicular to the direction of the fibers). If you have patellar tendinitis, review your training program to determine if you're "overusing" your knee in any way.

Osteoarthritis

Do you creak when you walk? Does it feel like your knee is filled with stalagmites that are sticking you like when your ex-girlfriend gets out her ex-boyfriend voodoo doll? Well it may be her or it may be osteoarthritis (OA). According to the American College of Rheumatology, osteoarthritis affects more than 21 million Americans, so you're not alone, buddy!

OA, or degenerative joint disease, results from degeneration of the joint hyaline cartilage. The causes of cartilage loss are multiple. Some kinds of OA are known to be hereditary, including the common form that causes enlargement of the knuckles. In most people, cartilage breakdown is due to both mechanical ("wear and tear") effects and biochemical effects. Therapy for OA includes both medication and other treatments that help to relieve pain and improve joint function.

Drug therapy should begin with simple pain relievers (acetaminophen) and progress to nonsteroidal anti-inflammatory drugs and/or intermittent corticosteroid injections. Recently, several thick liquids that resemble normal joint fluid have been approved for use for repeated injections into the knee joints. A cutting-edge orthopedist should be able to tell you if this method's right for you.

In addition, there's evidence suggesting that some dietary constituents may have a beneficial effect. Of course exercise is valuable, but weight training is especially beneficial. If the muscles are strong, they can take some stress off the joint. Reduction of weight on painful joints is important as well. Joint surgery to repair or replace seriously damaged joints may be required to end pain and restore functional mobility.

What Do You Need?

Now that you know all about your knees and some terrible things that can happen to them, what else do you need to know? You need to know that as a weight trainer, you're in the best position for keeping your knees healthy. Combined with proper mechanics and smart training, your weightlifting lifestyle can help keep your knees in top shape. With your knees as strong as possible, you'll avoid most injuries and no Kama Sutra position will be too difficult.