Introduction
Background
Bursae are small, synovial tissue-lined structures that help different tissues glide over one another, such as a tendon sliding over another tendon or bone. Bursae may become painful when irritated, damaged, or infected.
Pes anserine bursitis is a common finding in patients and/or athletes who present with complaints of anterior knee pain. The pes anserine bursa, along with its associated medial hamstring tendons, is located along the proximomedial aspect of the tibia. This condition is usually found in patients who have tight hamstrings, although it also can be caused by trauma (eg, a direct blow). In most patients, pes anserine bursitis is a self-limiting condition that responds to a program of hamstring stretching and quadriceps strengthening.
Frequency
United States
The exact incidence of pes anserine bursitis is unknown. It is not commonly recorded as an individual entity by many physicians but may be reported with the clinical diagnosis of anterior knee pain or patellofemoral syndrome. Pes anserine bursitis is recognized as occurring in a large number of patients who present to a physician's office with anterior knee pain.
Functional Anatomy
The pes anserine bursa is formed just proximal and medial to the primary attachment of the medial hamstring tendons on the proximal tibia.1 From proximal to distal, the medial hamstring tendons that form the roof of the pes anserine bursa are the sartorius, gracilis, and semitendinosus. The pes anserine bursa serves as a potential space where motion occurs between these hamstring tendons and the underlying superficial medial collateral ligament (tibial collateral ligament).
Sport-Specific Biomechanics
The pes anserine bursa serves as a space where motion occurs between the medial hamstrings and the superficial medial (tibial) collateral ligament. When a patient has tight hamstrings or experiences a contusion to this area, the synovial cells in the lining of the bursa may secrete more fluid and the bursa becomes inflamed and painful.
Clinical
History
The chief complaint of patients with pes anserine bursitis, either as a main component or as part of several causes of knee pain, is pain along the medial aspect of the knee. Although patients sometimes point to an area directly over the pes anserine bursa, they may often point to a rather diffuse region over the medial aspect of the knee. This diffuse pain may occur because many of these patients may also have plical irritation or medial joint compartment pathology (eg, medial meniscal tears, medial compartment arthritis).
(See also the eMedicine articles Medial Synovial Plica Irritation, as well as Knee, Meniscal Tears (MRI) [in the Radiology section],
Physical
On physical examination, the pes anserine bursa can be palpated at a point slightly distal to the tibial tubercle and about 3-4 cm medial to it (about 2 fingerbreadths). Pain in this area indicates an underlying inflammation of the pes anserine bursa or a bursitis. Palpation of this area of the knee is important in a patient who complains of medial-sided knee pain because the examiner needs to ensure that the pain is truly from joint line pathology or from pes anserine bursal pathology (or both).
Concurrent with the physical examination finding, the hamstring-popliteal angle should be assessed to determine the patient's underlying amount of hamstring tightness. This assessment is made by having the patient's hip flex to 90°, and then passively extending the leg. The angle formed between a perpendicular line to the femoral shaft and the tibial shaft is the hamstring-popliteal angle.
At its worst, pes anserine bursal pain is only mild to moderate. Intense pain could suggest a proximal tibial stress fracture.
Causes
The main cause of pes anserine bursitis is underlying tight hamstrings, which are believed to place extra pressure on the bursa, causing bursal irritation. In addition, some patients may have bursal irritation due to a direct blow and experience a contusion to this area, as well as resultant inflammation. Pes anserine bursitis is a common finding in patients who have concurrent Osgood-Schlatter syndrome, suprapatellar plical irritation, or other causes of joint irritation, which may make the hamstrings spasm (eg, meniscal tears, underlying arthritis). Patients with planovalgus feet and the resultant overpronation with running may also be at risk for irritation of the bursa.
(See also the eMedicine articles Osgood-Schlatter Disease and Medial Synovial Plica Irritation [in the Sports Medicine section], as well as Osgood-Schlatter Disease and Acquired Flatfoot [in the Orthopedic Surgery section].)
| ||||||||||||
References
Mochizuki T, Akita K, Muneta T, Sato T. Pes anserinus: layered supportive structure on the medial side of the knee. Clin Anat. Jan 2004;17(1):50-4. [Medline].
Forbes JR, Helms CA, Janzen DL. Acute pes anserine bursitis: MR imaging. Radiology. Feb 1995;194(2):525-7. [Medline]. [Full Text].
Rennie WJ, Saifuddin A. Pes anserine bursitis: incidence in symptomatic knees and clinical presentation. Skeletal Radiol. Jul 2005;34(7):395-8. [Medline].
Butcher JD, Salzman KL, Lillegard WA. Lower extremity bursitis. Am Fam Physician. May 15 1996;53(7):2317-24. [Medline].
Alvarez-Nemegyei J. Risk factors for pes anserinus tendinitis/bursitis syndrome: a case control study. J Clin Rheumatol. Apr 2007;13(2):63-5. [Medline].
Cox JS, Blanda JB. Peripatellar pathologies. In: Delee JC, Drez D, Stanitski CL, eds. Orthopaedic Sports Medicine: Principles and Practice. Vol 3. Philadelphia, Pa: WB Saunders Co; 1994:1249-60.
Hemler DE, Ward WK, Karstetter KW, Bryant PM. Saphenous nerve entrapment caused by pes anserine bursitis mimicking stress fracture of the tibia. Arch Phys Med Rehabil. Apr 1991;72(5):336-7. [Medline].
Kelly SS, Erpelding JM, Kobs J. Knee and lower leg. In: Snider RK, ed. Essentials of Musculoskeletal Care. Rosemont, Ill: American Academy of Orthopaedic Surgeons; 1997:306-65.
Marquis AM. Pes anserine bursitis. ONA J. Oct 1979;6(10):418-9. [Medline].
Medical Economics. Physician's Desk Reference. 54th ed. Montvale, NJ: Thomson Healthcare; 2000.
Mercier LR, Pettid FJ, Tamisiea DF, eds. The knee. Practical Orthopedics. 4th ed. St. Louis, Mo: Mosby-Year Book; 1995:226-7.
Muchnick J, Sundaram M. Radiologic case study. Pes anserine bursitis. Orthopedics. Nov 1997;20(11):1100; 1092-4. [Medline].
Seibel MO. Neuromuscular examination. In: Valmassy RL, ed. Clinical Biomechanics of the Lower Extremities. St. Louis, Mo: Mosby-Year Book; 1996:208-20.
Unlu Z, Ozmen B, Tarhan S, Boyvoda S, Goktan C. Ultrasonographic evaluation of pes anserinus tendino-bursitis in patients with type 2 diabetes mellitus. J Rheumatol. Feb 2003;30(2):352-4. [Medline].
Yoon HS, Kim SE, Suh YR, Seo YI, Kim HA. Correlation between ultrasonographic findings and the response to corticosteroid injection in pes anserinus tendinobursitis syndrome in knee osteoarthritis patients. J Korean Med Sci. Feb 2005;20(1):109-12. [Medline]. [Full Text].
Zaffagnini S, Golanò P, Farinas O, et al. Vascularity and neuroreceptors of the pes anserinus: anatomic study. Clin Anat. Jan 2003;16(1):19-24. [Medline].
Further Reading
Keywords
pes anserine tendonitis/tendinitis, knee bursitis, pes anserinus tendinobursitis/tendino-bursitis syndrome, PATB syndrome
