Many people suffer from chronic knee pain at some point during their life. An uncommon cause of knee pain is injury to the pes anserine bursa. Pes anserine was named for the structure that looks like a webbed foot of a goose. Translated from Latin, “pes” means “foot,” and “anserine” means “goose.” Pes anserine bursitis is often mistaken for another knee problem and can result from direct trauma, overuse, or as part of the secondary symptoms of another disease process.
It’s hard to determine how many people in the U.S. have pes anserine bursitis due to many overlap with other knee conditions. The prevalence has been reported as low as 0.33% in a study of 10,000 people, while another study that drew on data from a 2010 census in Mexico found it was the most common of the lower limb syndromes and pes anserine pain (not necessarily bursitis). This was often associated with steoarthritis in more than 90% of cases.
Pes anserine bursitis may also be a secondary diagnosis since it’s associated with being overweight and the presence of osteoarthritis. One series of imaging found knee osteoarthritis in 93% of patients with diagnosed pes anserine bursitis. There seems to be a relationship between diabetes and this condition, too.
Pes anserine bursa anatomy
The pes anserine bursa, one of 13 bursae around the knee joint, is located between the tibia and the tendinous attachments right below the middle of the knee joint. It also provides the medial side of the knee some stability.
Pes anserine is formed by the conjoined tendons of the gracilis, sartorius, and semitendinosus muscles as they form a broad structure that covers the medial part of the knee.
During knee motion, the pes anserine bursa is stressed during active flexion and adduction as the hamstring and adductor muscles contract and compress the bursa between the soft tissues and the bone. When pes anserine bursitis is present, the patient experiences pain with repeated knee flexion and extension (such as with stair climbing).
Knee joint stability can be influenced by atypical anatomy, arthritis, overuse injury, or trauma. The knee is stable in extension due to the bony junction provided by the screw-home mechanism of the knee.
When the knee is flexed, it relies on soft tissue structures for stability. The anterior and posterior cruciate ligaments primarily resist the sliding of the tibia on the femur and resist rotational forces at the knee. The medial and lateral collateral ligaments resist valgus and varus stress, respectively, and also assist in resisting rotation.
There also seems to be a relationship between pes anserine and overweight women. Women tend to have a wider pelvis which leads to a larger Q-angle. Larger Q-angles can be associated with tight adductors (and weak abductors).
Pes anserine bursitis causes
Bursitis is a general term used to describe irritation of any bursae. These are hollow structures are found throughout your body in areas of increased friction between soft tissue and bony structures. Conditions that cause persistent knee flexion such as a hamstring strain or calf strain could result in irritation to the bursa.
Inflammation of the pes anserine bursa is caused by too much friction to the bursa, degenerative joint disease, or direct trauma to the area.
Pes anserine bursitis may be associated with mechanical derangement, trauma, obesity, and overuse. Running, basketball, and racquet sports may contribute to the development of pes anserine bursitis, too.
A changed gait pattern caused by an attempt at avoiding knee pain could create lasting knee flexion as well. In repetitive activities, this flexed position can become problematic as it changes the wear patterns of the joint surfaces and doesn’t allow the normal metabolic processes that are part of soft tissue health to occur. In these cases, restoring full knee extension may be an easy and effective management strategy.
Pes anserine bursitis diagnosis
The best tests to confirm the presence of per anserine bursitis are tenderness to palpation, pain with active motion (the contracting muscle compresses the bursa), and passive motion (the lengthened muscle compresses the bursa).
Since the gracilis. sartorius, and semitendinosus muscles flex the knee and resist tibial rotation when you cross one leg over the other, this position can be a useful diagnostic exam where pain is a positive sign. Also, you might report weakness, stiffness, and decreased range of motion around your knees.
Tenderness is a cardinal sign of bursitis while inflammation may or may not be present. Those with an established diagnosis of osteoarthritis of the knee should be carefully screened for pes anserine pain and bursitis.
The classic symptoms of pes anserine bursitis include swelling and tenderness of the medial region of the knee along with diffuse medial knee pain. The pain may be located along the medial joint line or posteromedial joint line which could raise suspicion of meniscus involvement. Differential diagnosis should rule out medial collateral ligament injury, medial meniscus injury, Baker’s cysts, and semimembranosus bursitis.
Imaging isn’t typically required. The key to making this diagnosis is the location of tenderness. Pes anserine bursitis will be tender to palpation on the proximal medial tibia, three to five centimeters distal to the medial joint line of the knee.
Additional diagnostic criteria have not been established nor has the efficacy of using palpation to diagnose bursitis been established. Diagnostic imaging may be useful in the differential diagnosis of pes anserine bursitis. Both magnetic resonance imaging and diagnostic ultrasound can show other causes of local swelling, joint effusion, and rule out alternative diagnoses.
All that said, the diagnosis of pes anserine is not without controversy. Historically, MRI studies that showed the presence of fluid within the pes anserine bursa in patients with medial menisectomy lent to the validity of bursal involvement.
Conversely, Uson et al. examined ultrasounds of 37 patients with diagnosed pes anserine bursitis revealed that bursal enlargement was only present in two patients.
More recently, Unlu et al. studied 48 patients with type 2 diabetes and clinically diagnosed pes anserine bursitis found that less than 10% had ultrasonographic evidence of bursal swelling or pes anserine tendinopathy.
Participants in this study with pes anserine bursitis or tendinitis had medial meniscopathy, osteoarthritis, popliteal cysts, and suprapatellar recess effusions more often than participants in the control group.
It is possible that the pes anserine bursa is incorrectly identified as the faulty structure in these cases but a more plausible explanation for this pain has yet to be presented.
As with most knee pain conditions, the differential diagnosis for pain in the region of pes anserine is broad. Infectious pathology and gout should be ruled out at the initial examination. For example, compression to the saphenous nerve (likely through the adductor canal) can cause medial knee discomfort absent of any other pain or symptoms.
Pes anserine bursitis treatment and recovery time
Treatment for pes anserine bursitis is like most muscle and joint pain: rest, ice, and anti-inflammatory medications. Patients who are overweight or obese may also be deconditioned and may benefit from a strength training program, specifically to the quadriceps.
A 2016 study examined whether the presence of pes anserine bursitis was associated with greater impairment and disability in 176 patients with knee osteoarthritis. The study also sought to evaluate the effectiveness of local corticosteroid injection versus physical therapy. About 47% also had pes anserine tendino-bursitis.
Patients with and without the condition were separated into two groups. Group A received a hot pack, ultrasound, and transcutaneous electric nerve stimulation (TENS) for two weeks while Group B was given a corticosteroid injection to the most tender aspect of the pes anserine region.
Patients with osteoarthritis and pes anserine pathology had higher pain scores and more functional disability. Both physical therapy and corticosteroid injections were effective treatments for pain and no difference was found in functional ability between the two groups after treatment.
As a physical therapist, I would be remiss if I didn’t point out that a physical therapy session consisting of heat, ultrasound, and electrical stimulation is not evidence-based and should not be considered “normal.”
A similar study compared the use of Kinesio tape to physical therapy (hot pack, electrical stimulation, phonophoresis) and found both were effective in the treatment of pain with kinesiotaping being the better option.
It’s important that readers critically evaluate research methods rather than simply reading titles and conclusions.
In both of these studies, it is possible that the results would have been different if physical therapy had addressed muscle tightness, weaknesses, disability, and pain levels rather than merely using passive modalities.
The patient had decreased lower leg strength, gait deviations, lack of full knee flexion, and pain. Exercises that were used include:
- dead bugs
- hamstring eccentrics
- glute bridges
- and single-leg stance with toe taps.
After eight weeks, the patient showed improvements in moved better and had less pain and tenderness. The eight-week timeline may not be desirable in cases where pain is significantly limiting other aspects of life.
In that case, corticosteroid injection can be useful as an adjunct to therapy as it allows patients to perform both activities of daily living and rehab exercises that would otherwise be intolerable.
A study of corticosteroid injection alone in patients with osteoarthritis and pes anserine tendino-bursitis demonstrated that injection may be an effective first-line treatment for this condition.
Another study of 44 patients who received either naproxen or injection found that at one-month follow-up, 58% of those taking naproxen reported significant improvement with 5% of the condition resolved, while 70% of those who were injected were significantly improved and 30% of the condition had resolved.
As with any medical condition, musculoskeletal or otherwise, readers should consult with a physician or qualified medical professional to determine the best course of treatment for their condition. This article should not be considered a substitute for professional advice or care.
Pes anserine bursitis prevention
There are no proven methods for decreasing the likelihood of getting pes anserine bursitis. As with most joint conditions, maintaining a healthy weight and an active lifestyle may decrease the risk of developing pes anserine bursitis. If you already have type 2 diabetes, a healthy diet and exercise can assist with disease management which may prevent or delay the onset of other joint and muscle issues.
Massage therapy and pes anserine bursitis
Direct massage therapy for pes anserine bursitis is not well-supported in the scientific literature as patients with this condition are typically tender at the medial aspect of the knee and are unable to tolerate even light pressure on the area. But there is a role for massage therapy in treating such conditions.
A study comparing dynamic soft tissue mobilization and classic soft tissue mobilization techniques found the dynamic approach improved hamstring flexibility more in healthy men.
After the massage, those in the dynamic group gained an average of three degrees more flexibility than those in the standard or control groups. Therefore, dynamic mobilization techniques may be an effective treatment for patients with pes anserine bursitis when hamstring tightness is present.
Several studies have established the efficacy of massage therapy in patients with osteoarthritis. Patients who received Swedish massage therapy had improvments in pain, stiffness, function, and range of motion in three days.
It may also be worthwhile to teach patients with knee osteoarthritis self-massage techniques to use between massage therapy sessions. A 2013 randomized control trial looked at the outcomes of self-massage intervention to the quadriceps muscles group.
Although pes anserine bursitis is quite rare, it shouldn’t be overlooked because missing this diagnosis can result in prolonged pain and unnecessary treatments.