patella femoral pain

My musculoskeletal prac, included a lot of patients with anterior knee pain. I would say it was one of the most commonly seen area of visits by patients. I effectively treated this condition but I wanted to search the literature to see if my treatment techniques had any evidence base behind them.

Patellofemoral pain (PFP) is used to describe pain in and around the patella. It is an umbrella term used to embrace all peripatellar or retro patella pain in the absence of other pathologies. Other terms of chondromalacia patellae, anterior knee pain, patella malalignment and patellofemoral arthralgia have all been used synonymously with PFP. PFP is often seen in physically active individuals and may account for almost 10% of all visits to a sports injury clinic, reported incidence rates of 7% exist among young active adults. The cause of pains may differ among patients, with the pathologic origin of the disorder not clearly understood. Numerous structures within the patellofemoral joint PFJ are susceptible to overload. A number of these intra and extra articular components can be responsible for the generation on neurosensory signals ultimately responsible for the perceived pain.

PFP is believed to develop when an individual experiences an increase in the magnitude of the PFJ load. The increase in magnitude of load can be considered in two categories intrinsic and extrinsic. Extrinsic load being affected by the bodies contact with the ground therefore moderated by body mass, speed of gait, surface and footwear. Intrinsic factors can influence both the magnitude and the distribution of the PFJ load. Increased femoral internal rotation, knee valgus and subtalar pronation are all intrinsic factors that can contribute to the development of PFP. The overload the PFJ structures may be sufficient to initial a painful response. The increase in PFJ load results in PFP through injury of the musculoskeletal tissue from supra-physiological loads, either single maximal loads or lower repetitive loads. Injury to these tissues initials a cascade of events encompassing inflammation of the peripatella synovium through bone stress. Thus any number of pain sensitive structures can results in the conscious sensation of patella femoral pain.

Differential Diagnosis
• Patellar tendinopathy
• Fat pad impingements
• Osgood-Schlatter lesion
• Referred pain from hip
• Quadriceps tendinopathy
• Patellofemoral instability

Characteristics of Patellofemoral Pain
• Pain in anterior knee may be non-specific or vague. Medial, lateral or infrapatellar
• Pain aggravated by activities that load the patellofemoral joint – eg stairs, running
• Insidious onset unrelated to traumatic incident
• May have small amount of swelling above or below the patella

Functional Anatomy of the patella femoral joint
At full extension, the patella sits lateral to the trochlea. During flexion the patella moves medially and come to lie within the intercondular notch until 130 degrees of flexion, when it starts to move laterally again. The patellas mediolateral excursion is controlled by the quadriceps muscles, particularly vastus medialis oblique (VMO) and vastus lateralis (VL) components. With increasing knee flexion a greater area of patella articular surface comes into contact with the femur, thus offsetting the increased load that occurs with flexion. Loaded knee flexion activities subject the PFJ to loads many times the body weight (eg 7-8 times for climbing stairs) Anatomically the lateral structures of the PFJ are much stronger than the medial structures, so any imbalance in the forces will cause the patella to drift laterally.

Intrinsic contribution factors
These factors may contribute to the development of patellofemoral pain
Remote factors
Increased femoral internal rotation
Increased knee valgus
Increased tibial rotion
Increased subtalar pronation
Inadequate flexibility
Local factors
Patella position
Soft tissue contribution
Neuromuscular control of the vasti

Diagnostic features of PFP
• Display typical clinical features without other pathology on the knee
• Positive McConnell’s Critical
• Pain on palpation of patella facet joints
• Medical Imaging
• X-ray – can show osteoarthritis and an increased likelihood of sinding-larsen-johansson lesion
• MRI- increasing popularity of investigating PFP, due to its capacity to image the patella articular cartilage.
The majority of patients do not require imaging although it may be useful to confirm a clinical impression obtained from the history and examination.

Evidence based Treatment
What work and what doesn’t

Based on summary of Literature found in Brukner and Khan (2006)

Multimodal Intervention – rest from aggravating activities, ice, short course of NSAID’s, electrotherapeutic modalities, mobilisation, acupuncture and taping.
Level 1 evidence
Taping – aim to correct abnormal position of the patella in relation to the femur.
Level 1 evidence
Strengthening exercises – VMO training program, generalised strength training
Level 1 evidence
Stretching—Stretching tight muscles—NA
Hip muscle retraining – retraining hip abductors and external rotators helps to control the lateral pelvis and has been associated with pain reduction in patients with PFP— NA (no available literature)
Foot Orthoses – in shoe orthoses can be an effective management for PFP
Insufficient evidience—Level 1
Surgery – to be avoided. In very resistant cases surgical options may be considered.


Thank you