eMedicine Specialties > Physical Medicine and Rehabilitation > Lower Limb Musculoskeletal Conditions

Pes Anserinus Bursitis

Author: P Mark Glencross, MD, MPH, FACOEM, FAAPMR, Occupational and Environmental Medicine, Physical Medicine and Rehabilitation, President of Florida Occupational and Environmental Medicine Consultants (FOEMC)
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Updated: Sep 10, 2009

Introduction

Background

Pes anserine bursitis (or pes anserinus bursitis) is an inflammatory condition of the medial knee. Especially common in certain patient populations, it often coexists with other knee disorders.¹ (See image below and Image 1.)

Pathophysiology

Pes anserinus is the anatomic term used to identify the insertion of the conjoined tendons into the anteromedial proximal tibia. From anterior to posterior, the pes anserinus is made up of the tendons of the sartorius, gracilis, and semitendinosus muscles. The tendon's name, which literally means "goose's foot," was inspired by the pes anserinus's webbed, footlike structure. The conjoined tendon lies superficial to the tibial insertion of the medial collateral ligament (MCL) of the knee.

Moshcowitz initially described pes anserine bursitis in the 1930s as an inflammation of the pes anserine bursa underlying the conjoined tendons of the gracilis and semitendinosus muscles and separating them from the head of the tibia.² He defined the condition based on his observation of this type of bursitis in older adults with arthritis. He also described the musculi sartorii bursa between the tendon of the sartorius muscle and the conjoined tendons of the gracilis and semitendinosus, which can communicate with the pes anserine bursa proper. For the most part, both bursae are regarded collectively as the pes anserine bursa. In nonsurgical knees, there is usually no communication between these structures and the knee joint itself.

The sartorius, gracilis, and semitendinosus muscles are primary flexors of the knee. These 3 muscles also influence internal rotation of the tibia and protect the knee against rotary and valgus stress. Theoretically, bursitis results from stress to this area (eg, stress may result when an obese individual with anatomic deformity from arthritis ascends or descends stairs). Pathologic studies do not indicate whether symptoms are attributable predominantly to true bursitis, to tendinitis, or to fasciitis, at this site. Panniculitis at this location has been described in obese individuals. However, controversy remains regarding the true pathophysiology of the clinical syndrome of pes anserine bursitis/tendinitis, because in many cases in which the disorder's presence is clearly suggested, imaging studies (ultrasonography) fail to demonstrate pathologic findings in the pes anserine bursa or tendon (see Special Concerns).

The muscles of the pes anserinus (sartorius, gracilis, semitendinosus) are each supplied by different lower extremity nerves (femoral, obturator, and tibial, respectively).

Frequency

United States

One clinic reported finding pes anserine bursitis in 41 of 68 patients who were referred for presumed osteoarthritis of the knee. Bursitis in all locations of the body has been reported to account for 0.4% of visits to primary care clinics; however, the incidence of bursitis in runners, including self-treated cases, may be as high as 10%. In one review of 509 magnetic resonance imaging (MRI) scans of symptomatic adult knees suspected of having an internal derangement, evidence of pes anserine bursitis was evident in 2.5%.

Mortality/Morbidity

In a descriptive study of 94 patients with non – insulin-dependent diabetes mellitus, pes anserine bursitis was reported in 34 patients.³ Of these individuals, 91% were women and 9% were men. Among affected women with diabetes, 62% had the disease bilaterally. No subjects in a control group had bursitis without diabetes. Pes anserine bursitis is associated with obesity, and on average, patients with diabetes in the study had greater body mass than did the controls. Researchers, however, reported that body mass alone did not explain the higher incidence of bursitis among individuals with diabetes.

Race

No race predilection for pes anserine bursitis is reported in the literature.

Sex

The incidence of pes anserine bursitis is higher among obese, middle-aged women. Among older individuals with arthritis, a slight preponderance of females over males is noted among patients with pes anserine bursitis arthritis. The prevalence of anserine bursitis in women may result from the broader female pelvis and the greater angulation of women's legs at the knees, placing additional stresses on these structures.

Age

Pes anserine bursitis is most common in young individuals involved in sporting activities and in obese, middle-aged women. This condition also is common in patients aged 50-80 years who have osteoarthritis of the knees. In a study of 745 adults aged 50 years or older, all of whom had knee pain, Wood et al found that non-articular conditions, including prepatellar, infrapatellar, and pes anserine bursitis, appear to significantly increase the knee pain in and functional limitations of older adults who are also suffering from knee osteoarthritis.¹

Clinical

History

Pes anserine bursitis can result from acute trauma to the medial knee, athletic overuse, or chronic mechanical and degenerative processes. An occurrence of pes anserine bursitis commonly is characterized by pain, tenderness, and local swelling. Typical findings reported within the subjective examination may include the following:

• Tenderness over the inner knee can occur, with pain upon ascending and, possibly, descending stairs.
• Pain may be noted when arising from a seated position or at night. Patients typically deny pain with walking on level surfaces.
• Local swelling may be noted.
• Chronic refractory pain can occur in the area during aggravating activities in individuals with arthritis of the knee or in obese females.
• A history of athletic activity is another typical finding.
  • Generally, susceptible persons are those who are involved in any sport that requires side-to-side movement or cutting. The incidence of pes anserine bursitis is higher among runners and in individuals who play basketball, soccer, and racket sports, in part because of the popularity of these activities.
  • Pes anserine bursitis also has been reported in swimmers; as a result, the condition occasionally is called breaststroker's knee, although this term usually refers to MCL strains. MCL pathology may coexist among athletes or other individuals.

Physical

• The hallmark physical finding in pes anserine bursitis is pain over the proximal medial tibia at the insertion of the conjoined tendons of the pes anserinus, approximately 2-5 cm below the anteromedial joint margin of the knee.
  • The bursa usually is not palpable unless effusion and thickening are present.
  • Palpable crepitus consistent with bursitis occasionally is observed.
• With the chronic variant in older adults, usually no pain is experienced with flexion or extension of the knee.
  • Local pain is frequently noted in the area of the bursa, but upon palpation, no pain should be noted at the joint line itself unless other conditions are active. Some researchers report pain along the medial joint line, mimicking a meniscal tear.
  • Noticeable bursal swelling is less frequent among elderly patients with concurrent arthritis. Bursitis is found more frequently on the right side than on the left, and approximately one third of patients have bilateral involvement.
• In the sports-related variant, symptoms may be reproduced with resisted internal rotation and resisted flexion of the knee.
  • Valgus stress may reproduce the symptoms in athletic individuals, making it hard to distinguish pes anserine bursitis from MCL injuries. Typically, painful tenderness in association with MCL injuries is superior and posterior to the pes anserine bursa.
  • If swelling can be traced more proximally along the pes anserinus tendons, a formal tendinitis may be present, and a snapping of the pes anserine tendons can occur.
  • An exostosis of the tibia has been described in athletes and may contribute to chronic symptoms.
• One investigator noted that up to 30% of asymptomatic people report tenderness when the area of the pes anserine bursa is pressed.
• Two case reports of large cystic swellings of the bursa that resolved with conservative management have been documented.

Causes

• Degenerative joint disease of the knee frequently is associated with bursitis. According to some investigators, up to 75% of patients with degenerative joint disease may have symptoms of pes anserine bursitis.
• Obesity has been found to be associated with pes anserine bursitis, particularly, according to several studies, in middle-aged women.
• According to an investigation of women aged 45-82 years, valgus knee deformity, alone or in combination with collateral instability, appears to increase the risk for the development of pes anserine bursitis/tendinitis.⁴
• Pes planus (ie, flat foot) may predispose patients to pes anserine bursitis and to other problems in the medial knee.
• Sporting activities that require side-to-side movement or cutting have been associated with pes anserine bursitis.
• Local trauma, exostosis, and tendon tightness may predispose patients to inflammation.
• In 2 studies, diabetes was linked to bursitis³ ; however, the extent to which patients were able to control the diabetes was not documented.

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