During walking and stair climbing the force across the knee joint is three to four times body weight. The American Academy of Orthopaedic Surgeons estimates the force between the knee-cap and femur is one-half body weight with walking and seven times body weight during deep squatting. Knee problems typically result in quadriceps muscle pain.
Anatomy
The quadriceps tendon has four muscles attached: rectus femoris, vastus lateralis, vastus intermedius and vastus medialis. The quadriceps tendon connects to the patella or kneecap, which connects via the patella tendon to the shin-bone or tibia. When the quadriceps muscle is contracted, the quadriceps tendon transmits the force to extend the leg.
Tendonitis
Quadriceps tendonitis can occur after overuse or when walking resumes after a period of inactivity. Quadriceps tendon tears happen after a jump or fall when a person lands on a partially flexed leg. The AAOS considers renal failure, gout, leukemia, rheumatoid arthritis, systemic lupus erythematosus, diabetes and use of flouroquinolone antibiotics or corticosteroids as risk factors for quadriceps tendonitis and tears that occur in middle-age and older adults. In younger adults overuse tendonitis occurs in the patellar tendon. Quadrceps tendonitis usually have a slow onset. It is most notable before and after activity. As the tendonitis progresses pain is felt during activities. With severe pain, buckling and giving way of the knee occurs.
Knee Swelling
Arthritis, an anterior cruciate ligament injury, meniscus tears and several other knee problems produce swelling in the knee that results in a weakness of the quadriceps muscle. Riann M. Palmieri-Smith PhD of University of Michigan has studied the affect of knee effusions on joint forces during jumping. When 2 tbsps of saline is injected into the knee joint there was inhibition of the vastus medialis. Increasing the saline injection to ¼ cup inhibited vastus medialis, rectus femoris and vastus lateralis. The knee shock absorption on landing from a jump was decreased by the weakened muscles. Palmieri-Smith believes the quadriceps weakness could be an adaptation to discourage use of leg when there is a knee problem.
Injury
Quadriceps pain can occur after an injury. When the ACL is torn, magnetic resonance imaging shows edema and changes in the bone. This deep pain can be felt as quadriceps pain. A hit to the thigh can cause a quadriceps contusion as well as a knee injury. University of Wisconsin describes pain after activity, blood collection or hematoma in the muscle, quadriceps weakness and an inability to bend the knee as signs of a contusion. Periodic ice, stretching and compression are the recommended treatments for the first two days.
Other Causes
Rare causes of thigh pain include a bone tumor in the knee or a stress fracture. Infection can cause severe pain, redness and fever. Urgent medical attention should be sought for infection, according to the AAOS.
Treatment
For tendonitis or knee effusions rest and icing are recommended. The hamstrings flex the knee; therapy after a quadriceps injury includes stretching tight hamstrings to decrease the force opposing the quadriceps, along with strengthening and stretching the quadriceps. The AAOS recommends surgery for most quadriceps tears.
References
- American Academy of Orthopaedic Surgeons: Your Orthopaedic Connection: Quadricep Tendon Tear
- "American Journal of Sports Medicine": Mechanics During a Single-Legged Drop Landing Quadriceps Inhibition Induced by an Experimental Knee Joint Effusion Affects Knee Joint; Riann M. Palmieri-Smith, Jennifer Kreinbrink, James A. Ashton-Miller and Edward M. Wojtys; 2007
- Univeristy of Wisconsin: Quadriceps Contusion, Sports Medicine Conditions and Treatments
- American Academy of Orthopaedic Surgeons; Comprehensive Orthopaedic Review: Lieberman, J, ed.; 2009
