What is your Fat Pad and where is it?
Your fat pad is a mass of closely-packed fat cells surrounded by fibrous tissue septa. It sits in the knee is at the front of the knee below the knee cap or patella, behind the patellar tendon. It's a richly innervated structure below the knee. It's a very flexible structure and is malleable during knee joint mechanics.
What is Fat Pad Syndrome/Impingement?
If the fat pad becomes irritated it can cause pain and inflammation over the anterior knee, below the knee cap (patella). This is known as fat pad impingement syndrome and infrapatellar fat pad syndrome. It is also known as Hoffa’s syndrome, as it was reported by Albert Hoffa in 1903.
This is commonly misdiagnosed as patella femoral dysfunction and may occur along with osteoarthritis in patellofemoral or tibiofemoral joint component.
What causes Fat Pad Syndrome?
* Irritation and inflammation of the fat pad in the knee may be acute or chronic in nature.
* In acute cases, it's usually due to trauma or fall over the anterior aspect of the knee causing pain and inflammation.
* In chronic presentation, it's secondary to abnormal biomechanics causing pain and discomfort. The causes of abnormal biomechanics can be due to activities that cause repeated extension, such as kicking, jumping, running and cycling.
* Increased hyper extension in the knee joints secondary to increased ligament laxity (genu recurvatum).Tightness in hip flexors, quadriceps may also predispose knee to fat pad syndrome.
* Repeated trauma or blow to anterior aspect of the knee can cause chronic scarring, which may increase chances of fat pad syndrome.
* It may occur secondary to osteoarthritis in the knee joint in more experienced runners.
* It's been noted clinically that runners with a marked rear foot stride or heel strike while running have increased extension at the knee during heel strike, which may predispose them to Hoffa’s syndrome.
What are the symptoms of Fat Pad Syndrome/Impingement?
* The most common symptom is severe pain in the anterior aspect of the knee.
* In acute cases there can be swelling noted over the sides of the patellar tendon and below the patella.
* These symptoms are worse after running, standing for a long time or after long walks.
What's the treatment and prognosis for Fat Pad Syndrome/Impingement?
* Ice application may help to relieve the acute pain.
* Anti-inflammatory medication may help to ease the pain.
* Taping the knee is a good method to resolve irritation and pain. A popular way to tape the knee is to relieve the compression of the inferior pole over the fat pad by using a tape across the superior pole of the patella. To unload the patella further, V-shaped tape is applied from the tibial tuberosity to both sides of the patella, causing further shortening of the patella. This is known as McConnell’s fat pad taping.
* Patients are advised to avoid pain-provoking sports and wearing flat footwear.
* Static contraction (isometrics) exercises for the quadriceps, hamstring and gluteal muscles can be safely commenced on the acute phase.
* As the acute symptoms resolve, strengthening is advised for the quadriceps and hamstring muscles.
* Following isometrics exercises, strengthening can be progressed in an open chained manner using ankle weights or elastic exercise bands.
* In the gym, knee strengthening using the curl, knee extension and leg press machine can benefit to strengthen the muscles. Hip strengthening is advocated, mainly for gluteal strengthening.
* A flexibility programme to encourage hip flexor and quadriceps stretching is recommended.
What's the recovery prognosis for Fat Pad Syndrome/Impingement?
* Generally, the prognosis is good. Most patients recover with conservative management in rehabilitation in 8 to 12 weeks.
* Steroid injections can be recommended in cases of severe pain.
* Surgery should be avoided if possible. In only extreme cases is surgery advised, but once the conservative rehabilitation has failed or if there's ossification and advanced degeneration noted in the joint.
How can you prevent Fat Pad Syndrome/Impingement?
* Incorporate hip and quadriceps stretching and a flexibility programme into your regime.
* Strengthening for quadriceps and hamstring muscles to avoid hyperextension at the knee.
* Hip strengthening and single-leg control exercises.
* Use of knee pads and knee guards to protect from repeated trauma.
* Barefoot and forefoot running has been proven to reduce the recurrent strain over the fat pad and reduce inflammation. However, this transition in running style must be done gradually and slowly after gait analysis and monitoring.
Omkar Sawant is a senior physiotherapist with Capital Physio