Are you suffering from a persistent case of pain, inflammation, and tenderness in your inner knee area? The problem could be Anserine Bursitis. Read on and know all about this muscle disorder, including its various causes, symptoms, diagnosis, and treatment options.
What is Anserine Bursitis?
It is an inflammatory condition of the inner (medial) knee at the bursa of the pes anserinus. It is a common problem in patients who have tight hamstrings and anterior knee pain. A bursa is a sac filled with fluid which helps in reducing the friction between two adjoining structures. The pes anserine bursa is located between the tendons of three muscles (sartorius, gracilis and semi tendinosis) and the broad ligament which runs across the inside of the knee joint. The pen anserine bursa is found at the top of the shin bone and just underneath the knee joint on the inside of the shin.
Anserine Bursitis Pathophysiology
The muscles involved in this condition are:
Picture 1 – Anserine Bursitis
- Gracilis – It flexes and medially rotates the tibia at knee which is innervated by the obturator nerve
- Sartorius – It helps the knee and hip flexion when sitting or climbing. It abducts and laterally rotates the thigh. It is innervated by the femoral nerve.
- Semitendinosus – It helps in flexing the knee and medially rotates tibia on femur when knee is flexed. It also medially rotates the femur when hip is extended. It counteracts forward bending at hips which is innervated by tibial nerve and common fibular nerve.
The Pen anserine bursa serves as a space where movement between the medial hamstrings and the superficial medial collateral ligament takes place. When a patient experiences tight hamstrings or a contusion to this area, the synovial cells present in the bursa lining secrete more fluid and the bursa gets inflamed and painful.
Anserine Bursitis Causes
It is primarily caused due to the tightness of the hamstrings underneath. The hamstrings exert extra pressure on the bursa which leads to its irritation. Some patients may have bursal irritation due to a direct impact and experience a contusion to this area as well as resultant inflammation. Patients with planovalgus feet, and an over-pronation that occurs later, may also be at risk of suffering from an irritation of the bursa.
The bursa lies under the three tendons. Any movement that repeatedly makes use of these three tendons it increases pressure on the bursa and cause bursitis. Sports activities that constantly use these movements are probably going to irritate the bursa which includes golf, dancing, running and basketball.
The trigger factors for Anserine bursitis include:
- Injury to the large ligament on the inside of the knee, (the medial collateral ligament).
- Underlying osteoarthritis of the knee
- Flat feet
Anserine Bursitis Symptoms
The symptoms of this condition are:
- Medial knee pain, which occurs on the inside of the knee or upper shin just below the knee joint.
- Pain, which develops over time and is not caused by an injury or incident.
- Tenderness, which is experienced over the lower and inside part of the knee.
- Swelling of the area over the lower inside of the knee.
Pes anserine bursitis does not cause the knee to lock or give way.
Some patients experience pain in the center of the tibia. This takes place when other structures, such as the meniscus, are also damaged. The pain worsens with exercise, climbing stairs, or activities which cause resistance to any of the tendons.
Anserine Bursitis Diagnosis
The diagnosis of Anserine bursitis involves analysing the medical history of patients and a clinical exam. These help physicians to distinguish the disorder from other causes of anterior knee pain, such as arthritis or patellofemoral. An X-ray is needed to make sure that there is not any fracture due to stress or arthritis. An MRI scan may be required to detect damage to other areas of the medial compartment of the knee. If an infection is detected, a sample of fluid from the bursa may be removed and tested. An examiner is also likely to evaluate hamstring tightness. The assessment is done in the supine position; the hip is flexed to 90 degrees. The knee is stretched as far as possible. The more the knee is stretched, tighter the hamstrings are. If a patient is able to straighten the knee all the way in this position, then he/she is unlikely to have developed tight hamstrings.
Anserine Bursitis Treatment
The treatment of the condition can be divided into non-surgical and surgical:
Picture 2 – Anserine Bursitis Image
The non-surgical treatments that are usually carried out for this condition include:
For patients who are experiencing anterior knee pain, modification of activities is necessary. Activities should be changed to allow the joint to calm down and relax the taut hamstring. This modification demands minimum usage of stairs, climbing and other activities that can lead to an irritation of the joint.
Patients who have developed this form of bursitis go through a hamstring stretching program and a concurrent closed-chain quadriceps strengthening program. This program is taught to the patient by an athletic trainer or physical therapist. Patients need to stretch their hamstrings often during the day and at times on an hourly basis. The quadriceps strengthening program is suggested to most patients due to other concurrent pathology in the knee. A regular program will eliminate the pain from anserine bursitis in about 6-8 weeks. Doctor may also prescribe a non-steroidal anti-inflammatory drug which may help reduce the inflammation.
Correction of lower limb biomechanics should be done to avoid the pain. Ice and Compression can also alleviate the pain and swelling. Ice can be applied to the area for about 20 minutes, 3-4 times a day. If there is no recovery after physical therapy, one can opt for local anaesthetics like lidocaine or apply Corticosteroid injection directly into the bursa. Only 3 injections should be used over a period of one year. The injections should have a 1 month gap in between.
If non-invasive medical treatment options fail to improve the condition, surgery may be required to remove the bursa. The requirement of surgery is very rare in Anserine bursitis. Operation is recommended in patients who have low immunity levels in their body. Surgical decompression of the bursa is performed in such cases.
Anserine bursitis is a self-limiting condition. Even in severe cases, it generally responds efficiently to treatment and resolves without any further intervention. Athletes have to perform hamstring exercises and CKC quadriceps strengthening on a regular basis. They can return to normal sports activities when the symptoms no longer show up during certain activities. The knee needs to be covered by a protective gear for those who participate in sports. During the rehab process, the activity level and duration are gradually increased. If the symptoms do not come back, athletes can return to a normal lifestyle and go on to participate in all activities.