Functional Fitness and Knee Pain:
Understanding the basic logistics of common problems.
Dr. Lynn Felege, PT, DPT – August 17, 2015
For appearing physically simple, the knee joint is much more complex than most people realize. Pain can seem complicated and the advice given to treat chronic symptoms can be convoluted. This article is intended to clarify the most common knee complaints and their sources, and discuss how Functional Fitness can help reduce pain, restore proper joint mechanics, and normalize or increase activity tolerance.
Think of the knee as an intersection between the upper and lower leg, where your thigh bone (the femur) meets the shin bone (the tibia). The primary motion of the joint is to bend and straighten, allowing us to walk, negotiate stairs, and sit. But there are significant secondary forces of rotation that allow running, pivoting, squatting, jumping, and cutting. These dynamic, loaded movements are where most people get into trouble. Inadequate muscle strength or congenital variances in alignment can cause breakdown of specific tissues and/or predispose certain tissues to injury. For the sake of simplicity, only the primary offenders of knee pain will be discussed here:
Meniscus: The “shock-absorbers” of the knee, these are two C-shaped pieces of cartilage meant to buffer compression forces. The medial meniscus is larger and more commonly torn because it’s attached to the joint capsule, MCL, and a portion of the ACL. It can be torn during twisting (like a slip and fall) or as a result of repetitive pounding with improper joint alignment.
ACL: The Anterior Cruciate Ligament (ACL) runs through the center of the knee from the femur to the tibia, and acts as a restraint against the tibia from sliding forward and rotating inward. It is most commonly torn when the knee is twisted with the foot on the ground, as in awkward landings, slipping during a cut, or mid-leg tackles.
MCL: The Medial Collateral Ligament (MCL) runs from the femur to the tibia along the outer portion of the joint. It acts to restrain side-to-side translation between the bones, and can be injured with the same mechanisms as the meniscus and ACL.
Articular Cartilage: Lines the bottom of the femur and acts as a lubricant between boney sliding surfaces. It also gives additional shock absorption to the joint and is typically injured with repetitive pounding (think life-long runners).
Patellar Tendon: This is outside the knee joint capsule and connects the base of the knee cap to the front of the shin. It acts to keep the knee cap moving properly during bending and straightening of the knee, and is most commonly aggravated as a result of improper joint alignment and/or muscle imbalance between the quadriceps, hamstrings, and iliotibial band.
Genu Valgus: Medical term for someone who is “knock-kneed.” This alignment predisposes people to compression and breakdown of medial tissues of the knee, and is often accompanied with being flat-footed. This combination results in improper patellar motion, weak quadricep muscles, and tight lengthening of tissues along the outside of the thigh. This renders the knee much less effective at absorbing compression and increases the chance of arthritic breakdown.
Genu Varus: Medical term for someone who is “bow-legged.” This alignment predisposes people to compression and breakdown of lateral tissues of the knee. While considered somewhat less harmful than valgus positions, varus alignments can equally alter the joint’s ability to properly absorb compression.
“What makes my knee(s) hurt like this?”
While knee pain can seem confusing and unpredictable, certain tissues will typically offer particular pain descriptors. This list is not intended as a “be-all, end-all”for diagnosing knee pain, but here are some typical pain patterns for the knee:
“Painful buckling, clicking, locking”: These complaints are often sourced from meniscus issues. This type of cartilage is capable of fraying without being fully torn, and sometimes that frayed tissue can become trapped within the joint space and limit normal ranges of motion. Certain portions of the meniscus have blood supply, so even frayed or torn tissues in these portions may heal themselves with time and proper training. Continued squatting within pain-free ranges of motion, using lighter weight and emphasizing a strong outward knee drive can help reduce the soft tissue impingement.
“Instability”: The most common complaint of ACL disruption (note: the ACL can be strained without being torn). Certainly this is the knee injury requiring the most caution, and the more unstable the knee feels, the more likely it is that a full ACL rupture is present and medical attention should be sought. However, continued squatting within pain-free ranges of motion, using lighter weight and emphasizing a strong outward knee drive will keep the quadriceps strong, promote synovial fluid production, and optimize recovery if surgery is warranted.
“Stiffness”: This complaint can come from any tissue damage, either soft (like an irritated tendon or ligament) or boney (like arthritis). “Stiffness”as a primary complaint is most commonly a result of arthritic changes, especially if present in both knees. Typically the articular cartilage is experiencing a degree of breakdown, and the joint isn’t producing synovial fluid the way it should. Moving the knee gently through progressive ranges of motion before getting out of bed or before standing after prolonged sitting can help. Continued squatting within pain-free ranges of motion, using lighter weight and emphasizing a strong outward knee drive will help with tissue repair and fluid production.
“Grinding”: This complaint often accompanies issues at the knee cap where the patella isn’t sliding properly along the outside of the knee joint. Alignment and muscle imbalance between the quadriceps, hamstrings, and iliotibial band are often to blame. Soft tissue mobilization, including cross-friction massage to the patellar tendon and foam-rolling the iliotibial band can help. Continued squatting within pain-free ranges of motion, using lighter weight and emphasizing a strong outward knee drive will help strengthen the quadriceps and normalize proper patellar mechanics.
“Wait a second…”
If you were paying attention, you noticed a pattern in how to treat knee pain… and it consistently involved movement, mobilization, and strengthening. No matter the injury, the body must move in order to repair itself. When it comes to the complex framework of cartilage, tendons, ligaments, and muscular actions of the knee, working within pain-free ranges of motion is crucial – but all roads lead to the need for motion. In most instances, dynamic activities like jumping and running should be scaled or substituted until consecutive, deep air squats can be performed pain-free and while maintaining proper “knees out” alignment. Emphasis on proper knee alignment cannot be stressed enough, and often this includes mobilizing the ankle and hip joints to promote proper movement throughout the kinetic chain. Diligent attention should be paid during every rep to ensure proper movement patterns – every rep, done right, every time… no “zoning out” just to get reps completed. Joint pain should never mean “permanent injury” if the proper steps are taken to fix the problem causing the pain.