The force at the foot during cycling is only 17-19% of the vertical force during running, (Farell, Reisinger & Tillman 2003) meaning the major contributor to anterior knee pain in cyclists is repetition. The repetitive flexion and extension of the knee during 1000’s of revolutions can irritate a fold of knee-joint capsule tissue known as the medial plica as it slides over the medial aspect of the thighbone (femur) or becomes pinched between the femur and kneecap. The medial plica may also become irritated from acute trauma such as a crash onto the front of the knee.
Medial plica syndrome usually presents with a superficial, local dull ache in the anteromedial aspect of the knee. Pain can often be accompanied by snapping or a clicking sensation over the medial femoral condyle (thighbone). A symptomatic thickened plica may be palpated over the medial aspect of the thighbone while the patient flexes and extends the knee. There may also be a small amount of swelling/puffiness in the region.
Imaging (MRI, ultrasound) usually reveals nothing but may be useful in excluding other pathology.
Initial treatment involves pain relief, reduction of inflammation and limiting aggravating activities. Anti-inflammatory medication and/or a cortisone injection may be indicated after consultation with your doctor. Once the acute pain and inflammation has settled (usually 2-3 days) it is time to address the causative factors and initiate a gradual return to cycling.
A bike position with the seat too low or too far forward can cause overuse and stretch of the quadriceps muscles, increasing tension of plica and anterior soft tissues over the thighbone. Reduced lower limb control may result in increased adduction and internal rotation of the thigh (knee tracking towards the frame) placing tension on anterior medial structure of the knee. Physiotherapy will help by increasing joint range of movement (especially knee flexion), tissue extensibility and correcting muscle activation dysfunction and lower limb control to reduce symptoms and prevent reoccurrence.
So if you are suffering knee pain and are contemplating taking up cycling to reduce the load on your knees, be aware of the most prevalent injury in cyclists.
Photo: Graham Cook