Patellofemoral pain syndrome is caused by excessive stress to the knee due to extreme physical activities in patients with mal-alignment of the knee joint. Unlike several other conditions that cause knee pain
, cartilage changes are not noted in runner’s knee.
Anatomy of the Knee Joint
The knee joint is a major joint of the body that allows lower limb movements. It is the meeting point of the lower end of the thigh bone or femur, and the upper end of the leg bone or tibia, and the patella. The knee consists of two joints, that is, the tibiofemoral joint which joins the tibia to the femur and the patellofemoral joint which connects the kneecap to the femur. These two joints function together to produce a hinge joint that allows movements of the knee.
The femur has inner and outer prominences called the medial and lateral condyles, respectively. The groove between the prominences is called the trochlear groove. A small bone called the patella or kneecap snugly fits in this groove. Articular cartilage lines the lower end of the femur, the trochlear groove the inner side of the patella, as well as the upper end of the tibia. Synovium, which is a thin tissue, lubricates the joint and facilitates bony movements.
Unfortunately, the lateral condyle of the femur is a little less prominent as compared to the medial condyle, which favors outward movement of the patella especially when the knee is bent. There are several tendons and ligaments around the knee joint, which prevent displacement and stabilize the knee joint. These include:
- The quadriceps tendon, which attaches the quadriceps muscles to the patella
- The patellar tendon, which extends from the lower end of the patella to the tibia
- The medial and lateral retinacula, which are bands of fibrous tissue on either side of the knee
- The iliotibial band, which extends from the pelvis to the tibia bone of the leg
What are the Causes of Runner’s Knee / Patellofemoral Pain Syndrome?
Runner’s knee can affect one or both the knees. The main factors associated with patellofemoral pain syndrome are:
- Excessive stress to the knee joint, as seen in runners, other athletes as well as non-sports persons who are very active. It is associated with repeated activities like climbing stairs and squatting. Using improper sports training methods or sports equipment may also increase the stress on the knee joint
- Factors that cause mal-alignment of the knee joint and instability of the patella, as a result of which the patella is pushed more outward. These factors include:
- Mal-alignment of the bones at the knee, resulting in bow legs
- Knee spine syndrome, where inclination of the sacrum is around 5 degrees less than normal
- A tight iliotibial tract
- An imbalance in the thigh muscles that act on the knee
- Laxity of ligaments at the knee
- Foot problems that cause the leg to rotate inwards
- Weakness of hip muscles
What are the Symptoms of Runner’s Knee / Patellofemoral Pain Syndrome?
Symptoms of patellofemoral pain syndrome or runner’s knee include the following:
- Pain in front of the knee just behind the knee cap; pain in other parts of the knee may also be noted. The pain increases on bending of the knee, or during squatting
- Feeling of a crepitus or a grating feeling on moving the knee
- The pain can increase by long periods of sitting with the knees bent, therefore the condition is also referred to as ‘movie-goers knee’
- Mal-alignment of the knee joint or instability of the patella may be noted on physical examination. The angle between the tibia and the femur, called the Q-angle, may be increased
- Sometimes, swelling around the patella may be noted
- Inability to move the knee freely
How is Runner’s Knee / Patellofemoral Pain Syndrome Diagnosed?
Patellofemoral pain syndrome or runner’s knee is diagnosed based on:
- Health history of the patient
- Physical examination of the knee and the surrounding structures including alignment of the feet, strength of the hip, thigh and leg muscles, as well as walking and running patterns
- The tests used to examine patellofemoral joint or runner’s knee are the Q-angle test, the patellar apprehension test, Clarke's sign (patellar grind test) and the patella alta test
- Imaging tests like X-ray, CT or MRI scan
These help diagnose the condition and eliminate all other causes of anterior knee pain, and arrive at a diagnosis of patellofemoral pain syndrome. Conditions which also produce anterior knee pain include:
- Trauma, fracture, tumor or loose bodies in the knee joint
- Chondromalacia patellae, where there is softening of the cartilage of the knee joint
- Patella subluxation, where the patella repeatedly slips out of its position
- Inflammatory conditions like arthritis or bursitis, or iliotibial band syndrome where the lower end of the iliotibial band is inflamed
- Patellar tendinopathy, which affects the patellar tendon
- Osgood-Schlatter disease, which affects the attachment of the patellar tendon to the tibia
- Hoffa’s disease, where the fat below the patella gets pinched
How do you Treat Runner’s Knee / Patellofemoral Pain Syndrome?
Treatment of patellofemoral pain syndrome or runner’s knee involves:
- Using the RICE method (Rest, Ice, Compression, Elevation). Ice can be applied on the knee for 15-20 minutes to relieve pain. The patient should take rest and avoid painful physical activities
- Painkillers over a short duration to control the pain
- Physiotherapy, with exercises directed at stretching and strengthening the muscles of hip, the thigh and the iliotibial band and to improve stability of the trunk. A massage may help in loosening tight structures like the IT band and lateral retinaculum
- Taping of the knee with McConnell tape to prevent outward movement of the patella and for short-term relief of pain
- Application of a patella tracking knee brace, if necessary, to keep the patella in place
- Insoles or foot orthotics to correct foot deformities if present, which may cause knee misalignment
- Very few patients may require arthroscopy surgery that can be performed for diagnosis and treatment of joint abnormalities. A tibial tubercle transfer may be done through an open surgery to realign the kneecap by relocating the patellar tendon along with a part of the tibial tubercle, which is the bony prominence on the tibia
How do you Prevent Runner’s Knee / Patellofemoral Pain Syndrome?
Some ways to prevent patellofemoral pain syndrome or runner’s knee are the following:
- Avoid prolonged bending of the knee like during squatting
- Consult a physiotherapist if you suffer from mal-alignment of the knee
- If you are into competitive sports, make sure you have a good trainer who understands such conditions and can give you correct training. Also, use correct equipment for training and appropriate shoes for your activities
- Do adequate stretches in your warm up exercises before beginning any physical activity
- Keep your weight under control to avoid stress on your knees
Health tips to avoid patellofemoral pain syndrome or runner’s knee include:
- Avoid activities or positions of the knee that can cause pain
- Adopt exercises that do not put stress on the knee like swimming and cycling
- Reduce weight if you are overweight to reduce stress on your knee
- Warm up well before you undergo strenuous exercises and buy good quality shoes