Patellofemoral Pain Syndrome
40% of running related injuries affect the knee joint. Patellofemoral pain syndrome (PFPS) describes the group of symptoms that result from the anterior knee and the patellofemoral joint. PFPS arise as a result of ‘mal-tracking’ of the patella in the femoral groove during knee movement. A normal patella runs smoothly in the femoral groove. However, an imbalance in the forces acting on the patella, with relative weakness of the medial structures, may result in lateral drift and subsequent knee pain on movement.
Individuals suffer from diffuse knee pain, which is exacerbated by incline running, as well as walking on stairs and squatting. It is the most common overuse injury sustained by runners, with females affected twice as commonly as males.
Numerous factors contribute to PFPS including biomechanical abnormalities, such as valgus knee deformity (knock knees) and excessive foot pronation (roll onto the medial aspect) during gait. The vastus medialis obliquus (VMO) is one of the important structures that limit lateral tracking of the patella during knee movement. It is important to assess the function of the VMO by observing for obvious wasting and by asking individuals to contract their quadriceps muscles by pushing down into the couch to observe the patella tracking. This should be smooth and without gross side-to-side movement. Diagnosis is thus made on a clinical basis.
Treatment of PFPS is multi-faceted and includes pain control as well as managing any underlying biomechanical abnormalities. An initial period of reduced activity with regular ice and non-steroidal anti-inflammatory drugs (NSAIDs) aims to improve pain and localised inflammation.
The next stage of management addresses the contributing factors. Foot orthoses can be used to prevent excessive foot pronation, reducing valgus load at the knee and correcting lateral patellar movement. It is also important to ensure that the individual has appropriate training footwear, preventing excessive foot pronation during running.
Patella taping is often performed by a physiotherapist and aims to correct the imbalance of forces on the patella during knee movement. The patella can be taped from a lateral to medial direction ensuring that it glides more centrally and therefore more effectively in the femoral groove. This immediately reduces anterior knee pain and allows the individual to perform rehabilitation exercises, helping to optimise the function of the VMO. Physiotherapy interventions may include VMO and general quadriceps strengthening as well as stretching of the tight lateral patellar structures.
‘Lateral release’ surgery for PFPS describes the technique whereby the lateral retinaculum of the knee is incised with the intention of reducing some of the tightness. Onward referral may be required for intractable cases but there is little evidence to suggest that surgery improves PFPS and poor outcomes are not uncommon.