Knee Cap (Patellofemoral) Pain
Overview
The kneecap (or patella) sits at the front of your knee and lies in a groove on the front of your thigh bone or “femur”. Motion of the patella on the femur is called the “patellofemoral joint”. This joint is used to straighten your knee, using your quadriceps muscle. The patella sits within the quadriceps muscle and movement of the patella is guided by the pull of the quadriceps muscle, the alignment of the leg and the shape of the groove on your femur.
The patellofemoral joint is a very common source of anterior (front of the knee) pain in adults. Pain is precipitated by loading the joint, typically when arising from low seats or the squat position, getting in and out of the car or in particular when you descend stairs. Patients also describe a ‘grinding’ or ‘clicking’ sensation occasionally associated with pain on the front of their knee.
There are many causes for patellofemoral or anterior knee pain:
The most common cause is patellofemoral mal-tracking. The patella sits in a groove on the front of the femur and is pulled by the quadriceps muscle. The quadriceps muscle is supposed to ensure the patella glides smoothly within the groove. However if muscle control of the lower limb (including core and gluteal strength) is unbalanced or poorly coordinated, the patella gets pulled to one side (usually the outer side), drifting out of it’s groove on the femur. This causes rubbing rather than the smooth, natural gliding and hence excessive load is applied to one small area on the joint (like someone standing on your foot with a stiletto heel versus a broad heel). This problem is termed patellofemoral “mal-tracking”. The treatment for this problem is core strengthening, gluteal rehab and a quadriceps stretching and strengthen program to re-balance the patellofemoral glide, to encourage normal articulation within the joint (to track correctly).
Weight gain is another common cause of patellofemoral pain. Six times your body weight is loaded through your kneecap when you descend a step. Hence any weight gain gets magnified six fold in terms of pain. Other causes of anterior knee pain include sporting activities causing an ‘overuse’ problem, secondary to excessive or inappropriate training. Some patients have lower limb ‘mal-alignment’ with a combination of internal rotation of the femur (in-toeing), generalized ligamentous laxity and knock-knees. Soft tissue structures can be pinched or stretched in the region of the joint. The joint can be unstable due to previous trauma or have osteoarthritis.
Non-Surgical Treatments
Regardless of the cause of your patellofemoral pain, most patients can be treated without an operation. The main focus of treatment is to avoid over-loading the patellofemoral joint (weight loss and avoid overuse) and to improve your patellar tracking (physiotherapy guided rehabilitation).
Weight Loss:
This is self explanatory, considering six times your body weight loads through the patella when you descend a step – every extra pound counts!
Activity Modification:
There is no role for rest, but do avoid the over-use activities and continue with all activities that your pain will allow, like swimming and walking. You can’t really do yourself any more harm.
Painkillers:
Your GP will guide you through the different painkiller options, starting with paracetamol on an ‘as required basis’ and increasing through the many options from there, up to regular Paracetamol and anti-inflammatories taken in combination.
Physiotherapy:
The input of your chartered physiotherapist is vital to your recovery.
Stretching exercises for all the lower limb muscles are vital, especially prone quadriceps and IT band stretching with soft tissue mobilization. Typically all the lower limb muscle groups are too tight and need gradual stretching and mobilization.
Strengthening programs for your core, gluteal and quadriceps muscles to re-balance the way your patella tracks will stop the rubbing (mal-tracking) and ensure a return to the natural gliding motion, which is pain free. Strengthening exercises include heel lifts, knee extensions, resistance band training, plie knee bends, Swiss-ball squats, body weight squats, single leg squats, step-up and step-down training and lunges, gluteal rehab and core strengthening.
Taping techniques involve applying tape to hold your patella it in a better position, to ensure gliding rather than rubbing when you bend your knee. Taping can be useful in the short-term during your rehabilitation, under the careful guidance of your physiotherapist.
Wobble Board training will improve how your knee muscles function and fire.
Bracing or orthotics have a role to play in patients with mal-alignment.
It typically requires up to 3 months hard work for the non-surgical treatments to be effective.
Surgical Treatments
There are many surgical options from knee arthroscopy (keyhole surgery with camera into the joint) to open surgery including isolated patellofemoral joint replacement and total knee replacement. Occasionally a knee arthroscopy is useful to provide a ‘pain free window’, to enable appropriate work with your physiotherapist. Should any of these procedures become necessary, I will discuss them in detail with you.
