Toolbox: Cycling Knee Pain
One of the most common overuse bicycling injuries involves the knee. Chondromalacia patella, patellar and quadriceps tendinitis and patellofemoral pain syndrome are common diagnoses of anterior knee in competitive cyclists.
The high incidence of knee injuries in bicycling is not surprising given the biomechanics of force exertion through the lower extremities. It has been reported that knee and back injuries together caused 73.9% of overuse injuries resulting in time loss from training and competition. The knee’s extensor mechanism is comprised of the quadriceps muscle, the quadriceps tendon at the top of the patella, the patella and the patellar tendon at the bottom of the patella. The different parts of the extensor mechanism, individually or in combination, are susceptible to injury in bicycling.
Many labels are use to describe specific types of tendon injuries or “tendinopathies”, including tendinitis, tenosynovitis and tendinosis. “Tendinitis” is used to describe an acute tendon injury, ranging between 0 to 6 weeks, during which time there are is an active inflammatory response and increased vascularity which leading to symptoms of pain, swelling, redness and warmth. As tendon injuries become more chronic, there is an accumulation of non-inflammatory tendon degeneration and damage, leading to the description of “tendinosis”. Bicyclists are susceptible to both types of tendon injury in the quadriceps and patellar tendon.
Chondromalacia patella (CP) refers to degeneration and damage of the articular cartilage covering the underside of the patella. The degree of CP can vary from mild “softening” of the cartilage to complete loss of articular cartilage and exposure of bone of the undersurface of the patella or of the groove where the patella glides (femoral trochlea). CP and femoral trochlea articular cartilage degeneration can also collectively be called patellofemoral osteoarthritis (PF OA). Patellofemoral pain syndrome (PFPS) describes patellar knee pain that is not due to tendinosis, CP or PF OA. PFPS is considered to be a more of a functional problem related to muscular imbalances of the hip and quadriceps muscles with leads to patellar maltracking and consequently anterior knee pain.
Symptoms and Diagnosis
For PT and QT, one will usually notice more localized pain at the bottom or top of the patella, respectively, as opposed to pain behind or underneath the patella for CP and PF OA. With CP and PF OA, there can be an associated feeling of painful grinding behind the patella and even knee swelling. For those with PFPS, the pain is usually more generalized around the entire patella. For all these conditions, there can be pain during riding, but especially when more force is directed through the knee such as when riding in a high gear, up inclines, sprinting or when riding while standing. There can also be pain with deep squatting and kneeling and after sitting for prolonged periods of time with the knee in a flexed position. With PT, QT, and PFPS, plain film x-rays are usually normal but may show bone spurs at the insertion points of the quadriceps and patellar tendon at the patella for QT and PT, respectively.
Depending on the severity of CP and PF OA, plain film x-rays may show decreased patellofemoral joint space, bone spurs, thickening and cysts. Depending on severity of PT and QT, diagnostic ultrasound may show degenerative changes including hypoechoic regions, tendon thickening and calcific deposits. MRI is generally not required for diagnosis of PT, QT, CP or PF OA. For PFPS, radiological investigations are usually normal.
The recommendations for the initial conservative management of PT, QT, CP, PF OA and PFPS are generally the same. These include:
1. Modified training. Training intensity and volume should be decreased to a level which does not cause the reproduction of one’s symptoms. Also riding in lower gears at high RPMs and avoiding riding while standing will decrease the force transferred through the knees.
2. Adjusting bicycle positioning. Increasing the height of the bicycle seat and pushing the bicycle seat back may help to reduce the PF joint compressive forces and therefore, extensor mechanism knee pain.
3. Medication. NSAIDs can be taken orally or applied topically to reduce knee inflammation, pain and swelling symptoms.
4. Muscle strengthening. Progressive strengthening exercises of the quadriceps, especially of the inner quads (vastus medialis) should be started. Quadriceps strengthening exercises including leg extensions, leg press, step-downs and lunges. As one’s symptoms improve, the strengthening exercises can be performed with each leg individually. Adding and/or emphasizing the eccentric phase of quadriceps strengthening may be more beneficial for management of tendinosis compared to just doing concentric strengthening for the management of many tendinopathies. Eccentric strengthening refers to muscle contraction while the muscle fibers are lengthening. Eccentric strengthening exercises for the quadriceps includes “drop squats”, lunges, step-downs and dropping the weight more slowly while doing a leg extension. Strengthening exercises should initially be performed with lower resistance and higher repetitions. In addition to the quadriceps, strengthening of the hip and gluteal external rotation and abduction muscles and the iliotibial pain may help improved one’s knee symptoms. Maintaining flexibility of the gluteal, hamstring and quadriceps and calf muscles should be maintained and improved with stretching, foam rolling, massage therapy, and even yoga.
5. Bracing. For CP, PF OA, and PFPS, wearing a patella bracing may help promote more optimal patellar tracking while wearing a patellar strap may help symptoms of PT and QT.
6. Other treatments. If quadriceps strengthening and stretching exercises, NSAID medication and bracing do not adequately improve one’s PT and QT symptoms, less well-studied treatment options could be tried, including nitroglycerin patching, extra-corporeal shock-wave therapy and platelet-rich plasma injections. For CP and PF OA, intra-articular corticosteroid and viscosupplementation injections could be considered.
7. Surgical Treatment. Surgical approaches for management of chronic tendinopathy and CP and PF OA include open and/or arthroscopic debridement.
Written By: Dr. Victor Lun, MSc., MD, CCFP, Dip. Sport Med is a Sport Medicine physician who practices at the University of Calgary Sport Medicine Centre. He is the team physician for several winter and summer sport Canadian national sport teams.
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The information included in this article is for educational purposes only. It is not intended nor implied to be a substitute for professional medical advice. The reader should always consult their healthcare provider to determine the appropriateness of the information for their own situation or if they have any questions regarding a medical condition or treatment plan. Reading the information on this article does not create a physician-patient relationship.