Pes anserine bursitis denotes inflammation of the bursa that lies in the proximal part of the medial tibia, beneath the sartorius, gracilis and semitendinosus muscle tendons. Diabetes mellitus, obesity and female gender are shown to be most important risk factors. Pain and significant discomfort are main symptoms. Clinical findings and imaging studies such as ultrasonography or MRI are used for diagnosis. NSAIDs, corticosteroids and physiotherapy are mainstay of treatment.
Pain in the medial aspect of the knee that is accompanied with tenderness and/or swelling is the hallmark of pes anserine bursitis . Pain in the posteromedial part of the knee is also reported in many patients and may mislead the physician toward other disorders . Passive internal rotation and active external rotation of the knee causes aggravation of symptoms , which can also be reported when descending or ascending stairs , whereas difficulties when standing up from a chair or bending of the knee may also be encountered .
A thorough physical examination and patient history that includes information regarding signs and symptoms and when are they aggravated are key steps in the diagnostic workup, since pes anserine bursitis is primarily diagnosed on clinical grounds . The exact site of pain should be identified by both superficial and deep palpation and pain-producing movement should be performed during physical examination in order to solidify the diagnosis. Imaging studies such as ultrasonography and MRI have shown to be useful for some patients, but inconclusive results are common. The appearance of fluid beneath the pes anserineus tendon near the joint line at the medial tibia can be found on MRI , which is considered to be a superior method compared to ultrasonography. Imaging studies are, perhaps, more important for exclusion of other conditions that may present with similar symptoms, such as tibial stress fracture, osteoarthritis, popliteal cysts, infections or even malignant tumors .
The goal of therapy is to reduce inflammation and alleviate symptoms that are produced, which can be achieved through administration of several drugs. In patients with acute exacerbation of symptoms, cryotherapy for approximately 10 minutes consisting of ice packs may significantly reduce inflammation and swelling . Lidocaine and corticosteroid injection, however, is considered to be the optimal therapeutic regimen and shows prompt relief of symptoms  . Corticosteroids, compared to NSAIDs such as naproxen, have shown to be substantially more effective , but use of diclofenac and naproxen as injections have also shown to be effective in a subset of patients . Despite the effectiveness of therapy, bed red and physical therapy are equally important in the recovery process, consisting of rehabilitation, exercise and conditioning of muscles involved in movements that induce pain .
Although pes anserine bursitis is considered as a benign and self-limiting condition, significant disability that can last for up to a year is reported. With early recognition and appropriate therapy, complete recovery may be expected, but chronic pain and irritation can lead to long-term sequelae that may impair daily activities. Recovery rates may range from several months to 3 years , further emphasizing the importance of an early diagnosis.
Pes anserine bursitis stems from inflammation of the fluid-filled pes anserine bursa and various etiologies have been mentioned . Osteoarthritis is one of the condition in which pes anserine bursitis is frequently encountered and it is considered to be a prerequisite disease by many authors . Trauma, infection, bone exostosis, flatfoot, genu valgum (also known as knock-knee), posterior thigh muscle retraction and several other disorders have been linked with the development of this condition, but the underlying structure or disease responsible is often not found .
Reports of pes anserine bursitis in clinical practice are rare and epidemiological reports currently rely on single-center experiences and isolated case reports, as prevalence and incidence rates are not established. Prevalence rates in patients with knee problems was shown to be around 2.5% in certain studies, whereas approximately 20%-45% of patients suffering from symptomatic osteoarthritis develop pes anserine bursitis   . Rare studies have determined that up to 5% of asymptomatic patients have fluid-filled bursae which may predispose them to inflammation . Despite the scarcity of epidemiology studies, risk factors have been well-established. Pes anserine bursitis is much more commonly diagnosed in females, presumably due to a wider pelvis and consequent angulation of the knees that results in increased pressure of the area where pes anserinus bursa is located . Diabetes mellitus and obesity are also important factors, together with long-distance running that can cause significant stress on the medial aspect of the knee . Rare cases where rheumatoid arthritis was the presumed risk factor were mentioned in literature .
The pes anserine bursa lies just beneath the site where the attachment of three muscles to the medial aspect of the tibia takes place. The sartorius, gracilis and semitendinous muscle form the pes anserine tendon and are principally involved in knee flexion, while medial rotation is their secondary role . The bursa provides functional support to the knee by allowing friction and absorbing pressure exerted by muscles and additional structures in the vicinity. Lying below the pes anserine tendon, the bursa aids in protecting the knee from rotational and valgus stress injury . Regardless of the cause, increased pressure inside the bursa leads to fluid accumulation, swelling and inflammation, which manifests with either mild, moderate or severe disability. The disease often has a gradual onset and the process of inflammation causes progressive worsening of pain and reduced mobility . Its exact association with diabetes, osteoarthritis and other conditions that are considered as risk factors remains to be solidified.
Preventive strategies should be turned to alleviating pressure and reducing the factors that promote stress to the pes anserineus tendon. A thorough warm up prior to exercise, especially when running, is vital in reducing the risk of injury, whereas weight loss should be recommended in all obese individuals, especially women, in order to reduce the burden of the lower skeleton.
Pes anserine bursitis is a condition in which inflammation of the pes anserine bursa occurs that results in pain and causes significant discomfort . It was initially described almost 80 years ago, when a small group of women reported knee pain and difficulty walking up or down the stairs . Pes anserinus (Latin for "goose foot") is a term that represents the combined insertion of sartorius, gracilis and semitendinous muscle tendons onto the medial aspect of the tibia in a goose foot-like formation . Knee flexion and medial tibial rotation are the two principal functions of these muscles and their role in protection from knee rotational injury is well established . The pes anserinus bursa, situated between the tendons on one side, and the tibial collateral ligaments together with the medial tibial condyle on the other , is filled with small amounts of synovial fluid and provides both frictional and structural support. Although the exact cause and pathogenesis of pes anserine bursitis remains unknown, infections, bone exostosis, medial meniscus damage, pes planus (flatfoot) and retraction of posterior thigh muscles are considered as possible causes . Mechanical factors such as obesity and increased body mass index, as well as diabetes mellitus, trauma, overuse caused by exercise (running or swimming) and degenerative joint disease have all shown to be strongly associated with the development of this condition . A strong predilection toward female gender has been established. The majority of patients present with vague or moderate knee pain that can be accompanied by tenderness and edema in the region of the proximal medial tibia . Symptoms can be aggravated when climbing stairs or getting out of a chair . The diagnosis of pes anserine bursitis may be difficult to attain due to numerous conditions of the knee that may be included in the differential diagnosis (such as injury to the medial meniscus, degenerative arthritis, L3-L4 radiculopathy, stress fractures, etc.) . Clinical criteria may require support from imaging studies such as ultrasonography or magnetic resonance imaging (MRI) to confirm the diagnosis, but inconclusive results are frequently obtained, which is why the diagnostic accuracy primarily depends on the experience of the physician. Treatment aims to alleviate symptoms through use of non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids and lidocaine injections, but also physiotherapy and cryotherapy in acute inflammation . Although the condition itself does not put the individual at significant risk, many patients experience symptoms for up to 1 year and recovery rates are shown to last for up to 3 years . Because pes anserine bursitis can markedly impair the quality of life and ability to perform daily activities, early recognition of the disease is essential.
Pes anserine bursitis is a condition that develops from inflammation of a small fluid-filled structure (bursa) located on the inner side of the knee. The pes anserine bursa lies just beneath the pes anterine tendon, the site where three muscles (sartorius, gracilis and semitendinous) attach and its primary role is to protect the knee from stress and friction caused by activation of these muscles. The term pes anserine stems from the Latin word "goose foot" and the condition is named after this term due to a striking resemblance of the three muscles and their attachment to a goose foot. The principal function of these muscles is flexion and internal rotation of the knee and their overuse in long-distance runners can predispose individuals to this condition. Other causes of pes anserine bursitis include trauma, preexisting osteoarthritis and obesity. Females are much more commonly affected than males, presumably due to anatomical differences in the pelvis and knee angulation that results in increased amounts of stress in that area. The main complaint is pain that is aggravated by various movements, such as ascending or descending stairs, inward knee rotation, or when standing up from a chair. Pain can be accompanied by swelling and tenderness, which serve as main diagnostic clues for the physician, since pes anserine bursitis is primarily diagnosed using clinical criteria. Imaging studies such as ultrasonography and magnetic resonance imaging (MRI) can be of use in some patients, but their utilization is limited due to the delicate nature of the disease and very discrete pathological events. Treatment aims to reduce the symptoms and resolve any disability this condition has caused. Acute exacerbation of pain can be relieved with ice packs for approximately 10 minutes, but injection of corticosteroids and lidocaine has shown to be an effective method. Non-steroidal anti-inflammatory drugs (NSAIDs) are also beneficial in injection forms, but are shown to inferior to corticosteroids. Bed rest and physiotherapy guided by skilled professionals is equally important, especially in the recovery process. Once the pain has disappeared, strengthening of the muscles and weight loss in obese patients is highly recommend to prevent pain recurrence. The prognosis of patients in whom an early diagnosis is achieved is very good, but many patients report symptoms that last up to a year and long-term sequelae that can substantially impair the quality of life can occur without adequate treatment. Recovery rates last from several months to a few years, implying that patience and compliance with therapy is imperative.