What is it?
Anterior knee pain refers to a group of pathologies that cause discomfort at the front of the knee. It can be acute or chronic and be as a result of an injury or have a fairly non-specific gradual onset. Anterior knee pain in itself is not a diagnosis, more of a description of symptoms that can have a number of underlying causes.
Why does it occur?
Pain at the front of the knee can originate from many sites.
- Chondromalacia patellae
Chondromalacia patellae refers to softening of the articular cartilage on the back of the kneecap. This can lead to excess stress on the underlying bone and pain secondary to this. Chondromalacia patellae may be secondary to abnormal load distribution over the patellae due to maltracking or muscle imbalances. In some circumstances, normally in young females, it can have no precipitating cause.
- Patellar tendonitis
Patellar tendonitis also known as jumper’s knee is a condition whereby the tendon running from the kneecap to the shin bone is subject to repeated stress leading to tiny micro-tears within the tendon. The body attempt to repair this micro-tears and an abnormal cascade of healing and repair is initiated. The tendon becomes inflamed and weakened leading to discomfort and pain at the front of the knee. This pathology is often seen in overuse injuries in runners and jumping athletes particularly those with muscular imbalance due to tight quadriceps and hamstrings causing an increase strain on the patellar tendon.
- Medial plica syndrome and fat pad inflammation remnants of the knee cavity left from the embryonic development of the joint lead to synovial folds or plicae which are common in most knees. However on occasions if particularly large in an active person they can rub on the inside of the knee causing inflammation. Similarly behind the patellar tendon there is a specialised fat pad present in all knees which under most circumstances will not cause any problems within the knee. However on occasions often secondary to a period of inactivity followed by return to sports and muscle weaknesses leading to poor biomechanics, the fat pad can become pinched and inflamed leading to a cascade of inflammation and attempted repair. The chemical and mechanical irritation within the knee can lead to anterior knee pain.
What are the symptoms?
Anterior knee pain normally manifests as a discomfort behind the kneecap or just above/below the kneecap predominantly on activities that involve loading a flexed knee. Things that can be particularly troublesome are sitting with the knees bent for a prolonged period of time, walking up or down slopes or stairs, squats and lunges or sports that involve jumping or landing.
How is it diagnosed?
As anterior knee pain has a number of causative pathologies, a careful clinical examination combined with appropriate diagnostic imaging is essential. Your treating doctor will review your lower limb biomechanics and carefully examine your patellofemoral joint and the rest of your knee. Sometimes it is evident from this examination what the most likely cause of the symptoms is. However on occasions it may be necessary to have either x-rays or an MRI scan in order to differentiate between potential conditions.
How is it treated?
The management of patellofemoral pain is dependent on the causative pathology. More often than not, non-operative measures are appropriate and will lead to a resolution of symptoms in the vast majority of cases. This is generally focused around a physiotherapy regime looking at the biomechanics of your lower limbs, your core stability and patellofemoral tracking. On occasions physiotherapy can be augmented with appropriate injections to reduce the pain in your knee and allow you to do the exercises more effectively.
Some pathologies such as large inflamed plica or loose chondral flaps behind the kneecap that do not respond to non-operative measures can require surgery. Similarly in very refractory cases of quadriceps or patellar tendonitis where non-operative treatments have been exhausted, an operative intervention to debride the inflamed and damaged tendon tissue can alleviate symptoms.