Anterior knee pain

Introduction

First and foremost, ‘anterior knee pain’ is a symptom, not a diagnosis!

‘Anterior knee pain’ simply means ‘pain around the front of the knee’. Nothing more than that. There are numerous different potential causes of anterior knee pain, and the first and most important step is to work out exactly what the actual diagnosis is before one can then formulate an appropriate treatment plan … and potential surgical treatment comes way down the line.

One of the most important initial things is to specific very precisely exactly where the site of the symptoms is, and correlating this to the underlying anatomy normally cuts down the differential diagnosis (the list of possible causes) significantly.

Pain just below the kneecap:

Pain that can be pinpointed quite specifically to the area just below the kneecap can be due to:-

–       Patellar tendinopathy (patellar tendonitis or tendinosis)

–       Fat pad inflammation

–       Infrapatellar bursitis

–       Osgood Schlatter’s Disease / ossicles

Pain in the region around the actual kneecap itself can be due to:

Articular cartilage damage in the patellofemoral joint

–       Patellar maltracking

–       Patellar instability

–       Pre-patellar bursitis

Pain around the inner (medial) side of the front of the knee can be due to:

Medial Plica Syndrome

–       Medial meniscal tears

–       Articular cartilage damage to the medial femoral condyle

Pain around the outer (lateral) side of the front of the knee can be due to:

–       Lateral Plica Syndrome (not common)

–       Lateral meniscal tears

–       Articular cartilage damage to the lateral femoral condyle

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It is vital that any significant symptoms in your knee are actually diagnosed correctly, and for this it is important to see an appropriate specialist who will take a detailed history, perform a clinical examination and arrange whatever imaging investigations might be required.

What potentially might be going on under the skin and behind the kneecap at the front of the knee very often has no relation to whatever the superficial appearances of the front of the knee might be, from just visual inspection. Proper detailed imaging is of particular importance when trying to make an accurate and reliable diagnosis of the underlying cause of a patient’s anterior knee pain.

Investigation of anterior knee pain

X-rays

The best way to look for arthritis in the knee is with a good old fashioned X-ray. However, X-ray is also the best way of looking at the exact shape of the patellofemoral joint and of determining the degree of any potential patellar maltracking that might be present. In particular, special views of the knee looking from the bottom upwards with the knee slightly bent (called a patellar skyline view) are especially useful.

Ultrasound

The best test for looking for problems with the muscles, tendons and soft tissues at the front of the knee is ultrasound. Just like a pregnancy scan, ultrasound is performed by passing a probe over the knee with jelly on the skin. The scan is performed by a Consultant Radiologist (X-ray doctor), and is highly operator-dependent. With X-rays and MRI, it is the actual images that I personally want to see, not such a typed report. However, with ultrasound the images (which tend to be just a series of grey lines) have little meaning, and it is actually the radiologist’s report on the scan that’s important.

Ultrasound is particularly sensitive and accurate for diagnosing conditions such as bursitis, tendinopathy and muscle/tendon tears. At the same time, with ultrasound, if a specific area of inflammation is found (for example fat pad inflammation or inflammation under the distal ITB from ITB Friction Syndrome) then an ultrasound-guided steroid/cortisone injection can be given by the radiologist doing the scan. Ultrasound-guided injections are far more accurate than just ‘blind’ injection in clinic, and is the gold standard for many specific conditions.

MRI

If damage deeper inside the joint is suspected, such as damage to the articular cartilage, to the meniscal cartilages or to any of the deeper ligaments, then the best imaging modality by far is MRI. Having an MRI scan involves lying on a bed that goes part way into a large tunnel. Having the scan takes about 20 minutes and can potentially feel a bit claustrophobic, plus it is important to keep the knee very still during this period as any movement will cause blurring of the images.

In my practice, if I send a patient for an MRI scan then it is the actual images that I want to see, as I will go through all of these in detail, correlating any potential findings with the patient’s actual history, symptoms and clinical signs. MRI scans are about 90+% accurate, which means that they can sometimes miss some smaller things, with a small potential false +ve and false –ve rate. Just having an MRI report only, without reviewing the actual images, is really not sufficient. I like to go through the actual MRI images with my patients in clinic after any scan, using this as an opportunity to explain to the patient the anatomy in the knee and any potential damage that might show up, as this aids enormously with most people’s understanding of what is actually happening with their knee.