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 Table of Contents  
Year : 2020  |  Volume : 3  |  Issue : 1  |  Page : 28-30

Pes Anserine Syndrome and Bursitis in a Stroke Patient without Prior Knee Pathology: Diagnostic and Treatment-Learning Points

Department of Rehabilitation Medicine, Singapore General Hospital, Singapore

Date of Submission29-Jan-2020
Date of Decision06-Feb-2020
Date of Acceptance08-Feb-2020
Date of Web Publication17-Jun-2020

Correspondence Address:
Dr. Tan Yeow Leng
Department of Rehabilitation Medicine, Singapore General Hospital, Outram Road, 169608
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jisprm.jisprm_11_20

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Snapping pes anserinus is a cause of extraarticular medial knee snapping. It results from the translation of the semitendinosis or gracilis tendon during active knee flexion and extension. A 60-year-old female with left medullary infarct and no prior left knee pathology presented with left painful knee snap on walking 3 years after the stroke onset. Clinical examination detected a medial knee snap on the left knee extension. Dynamic ultrasound identified the semitendinosis tendon causing the knee snap. Magnetic resonance imaging of the left knee excluded intraarticular causes of knee snap and confirms soft-tissue edema and bursitis near the pes anserine. The patient was treated with local anesthetic injection and physical therapy with immediate pain relief. This case describes pes anserine syndrome in a stroke patient without prior knee pathology. Poststroke gait deviation can possibly cause repetitive excessive knee loading, leading to secondary musculoskeletal complications such as snapping pes anserinus.

Keywords: Knee, pes anserinus, snapping, ultrasound

How to cite this article:
Leng TY. Pes Anserine Syndrome and Bursitis in a Stroke Patient without Prior Knee Pathology: Diagnostic and Treatment-Learning Points. J Int Soc Phys Rehabil Med 2020;3:28-30

How to cite this URL:
Leng TY. Pes Anserine Syndrome and Bursitis in a Stroke Patient without Prior Knee Pathology: Diagnostic and Treatment-Learning Points. J Int Soc Phys Rehabil Med [serial online] 2020 [cited 2022 Dec 1];3:28-30. Available from: https://www.jisprm.org/text.asp?2020/3/1/28/287075

  Introduction Top

One of the noises heard in the knee is a snap which has various pathological causes. Snapping pes anserine, a cause of medial knee snap, results from semitendinosus or gracilis tendon translating over the bony structures during active knee ranging.[1] Painful snapping pes anserinus had been reported in young male without trauma, knee osteoarthritis, and osteochrondroma.[1],[2],[3] Herein, a 60-year-old female with stroke presented with left painful medial knee snap 3 years later. With clinical examination, dynamic ultrasound, and magnetic resonance imaging (MRI), the diagnosis was left pes anserine syndrome. Local injection, appropriate stretching, and strengthening exercises improved her pain and function.

  Case Report Top

Miss M, a 60-year-old female without prior left knee pathology, had left medulla infarct in mid-2014. She had severe motor impairment initially (Medical Research Council grading for upper limb 0, lower limb 1) but improved to 4 after 6 months of rehabilitation. Postrehabilitation, Miss M needed a walking stick for community ambulation due to residual motor deficits. She stopped outpatient rehabilitation after early 2015. In mid-2017, she started having left medial painful knee snap during active flexion to extension. From mid-2014 to mid-2017, there was no left knee trauma, although few episodes of near falls were described due to residual motor deficits. Her physiotherapy from mid-2014 to early 2015 did not revealed any physical injury to the left knee.

During the period of mid-2017 to early 2019, Miss M sought complimentary medicine treatment and primary health-care consultations for pain management. Oral paracetamol and nonsteriodal anti-inflammatory agents were prescribed. Miss M was told to have knee sprains or ligament sprains and was encouraged for investigations. She did not proceed with investigations despite no improvement in pain or knee snapping. By March 2019, Miss M consulted an internal medicine specialist for pain management due to persistent pain and snap. She was then referred to physiatrist for investigation, treatment, and recommendation of physical therapy.

Physical examination in mid-2019 at the physiatrist's clinic revealed tenderness over the posterior medial left knee with no joint effusion. Active range of motion of the left knee was full, but a physical snap was palpable over the same region on active left knee extension (over the last 30° of knee extension). Tenderness but no swelling was noted over the pes anserine insertion area. McMurry and Lachman tests were negative. No knee clicking or locking was noted.

Differential diagnosis of left medial painful knee snap included medial knee degenerative conditions, pathological plica, snapping knee syndromes, and patellofemoral instability [Table 1].
Table 1: Differential diagnosis of pathological sources of left painful medial knee snap

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Miss M agreed for further investigations. Left knee X-ray showed minimal osteoarthritis changes with no fracture. Dynamic bedside ultrasound revealed snapping of the left semitendinosus tendon from the posterior to medial over the medial femoral condyle on repeated knee flexion and extension [Figure 1] and [Figure 2]. Left knee pes anserine bursitis was also noted. MRI left knee revealed soft-tissue edema near the pes anserius tendons consistent with pes anserine bursitis. There was no joint effusion, synovitis, ganglion cysts, meniscal tears, or knee ligamental injuries. Based on clinical history, examination, dynamic bedside ultrasound, and knee MRI, the diagnosis was pathological left snapping knee syndrome.
Figure 1: Transverse ultrasound image of left posterior distal knee; the position of the left semitendinosis tendon and muscle at full knee flexion. ST: Semitendinosis muscle and tendon, MG: Medial head of the gastrocnemius, MFC: Medial femoral condyle

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Figure 2: Transverse ultrasound image of the left posterior medial knee at full-knee extension showing snap of the semitendinosis tendon (curve arrow) posterior medially over the medial femoral condyle

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Treatment recommendation at the physiatrist clinic included local steroid and analgesic injection coupled with physiotherapy. However, the patient chose to proceed with physiotherapyfirst. Miss M received 4 weeks of stretching exercises for the hip flexors, iliotibial band and calf muscles, and side step-strengthening exercises with resistance bands and inner thigh squats. On the second visit, there was no improvement in pain although the patient felt left lower limb was stronger with better knee control. She agreed for local injection of lignocaine and triamcinolone over the left pes anserine area and peritendinous region of semitendinosus. There was immediate pain relief. At 4 weeks, the patient remained pain free with less frequent knee snap.

  Discussion Top

Snapping pes syndrome has been reported in knee pathologies such as osteoarthritis with knee arthroplasty, osteochondroma, and blunt trauma with bony fragment.[2],[3],[4] We report snapping knee syndrome in a stroke woman without prior knee pathology. We postulated gait instability poststroke with near-falls could contribute to repetitive overload to the left knee. Snapping knee syndrome can be caused by various extraarticular and intraarticular structures.[5] We utilize dynamic ultrasound to create the extra-articular snapping phenomenon using the real-time visualization of involved soft tissues. With knee MRI, we further excluded intraarticular causes such as synovial nodules. In this case, the extraarticular structure causing the painful snap is the semitendinosis tendon.

Most case reports on snapping pes syndrome are on younger patients, athletes, or pediatric population with knee pathologies. Pain generators from pes anserine syndrome and bursitis in older stroke patients without knee pathology have yet been described. Karataglis et al. suggested repetitive overloading to anterior knee coupled with abnormal posterior inferior of the knee accessory might lead to the subluxation of the tendinous band.[6] In strokes with residual impairments and gait deviations, gait analysis as part of the follow-up to detect any secondary musculoskeletal complications is needed. Early detection of physical snap should be followed by suitable exercise prescription and medical treatment. These help to correct any gait abnormality, devise preventive strategies to avoid joint overloading, and prevent further exacerbation of snapping knee.

Second, ultrasound has sensitivity and specificity comparable to knee MRI.[7],[8] Snapping pes anserine syndrome can be misdiagnosed as knee sprain or ligamental injury without ultrasound.[1] Understanding various intraarticular and extraarticular knee snaps will be useful, and physicians should consider bedside sonography to facilitate the diagnosis and treatment.

There are various treatments of snapping pes syndrome [Table 2]. Physiotherapy focusing on functional capability and knee pain severity had been reported.[9] Ultrasound-guided injection of lignocaine and corticosteroid around the involved tendons could relieve the pain.[1] Pes anserine tendon surgical resection is considered if conservative measures fail.[10] In this case, local injection and physical therapy improved the pain, and hence, surgical option was not further explored. We highlight a stroke patient with left pes anserine syndrome and without previous knee pathology. Ultrasound and MRI are useful modalities to assist the diagnosis. Local injections should be considered early with appropriate physical therapy.
Table 2: Treatment strategies for snapping pes syndrome. In this case report, the patient responded well to physical therapy and local injection

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Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Shane AS, Lorenzo OH, Daniel PM. Snapping pes anserinus and the diagnostic utility of dynamic ultrasound. J Clin Imaging Sci 2017;7:39.  Back to cited text no. 1
Inui H, Taketomi S, Yamagami R, Tahara K, Tanaka S. Snapping pes syndrome after unicompartmental knee arthroplasty. Knee Surg Relat Res 2016;28:172-5.  Back to cited text no. 2
Sakamoto A, Matsuda S. Pes anserinus syndrome caused by osteochondroma in paediatrics: A case series study. Open Orthop J 2017;11:397-403.  Back to cited text no. 3
Knudsen R, Al-Aubaidi Z. Snapping pes syndrome with a loose bone fragment is a rare cause for medial knee pains. Ugeskr Laeger 2011;173:2350-1.  Back to cited text no. 4
Song SJ, Park CH, Liang H, Kim SJ. Noise around the Knee. Clin Orthop Surg 2018;10:1-8.  Back to cited text no. 5
Karataglis D, Papadopoulos P, Fotiadou A, Christodoulou AG. Snapping knee syndrome in an athlete caused by the semitendinosus and gracilis tendons. A case report. Knee 2008;15:151-4.  Back to cited text no. 6
Cook JL, Cook CR, Stannard JP, Vaughn G, Wilson N, Roller BL, et al. MRI versus ultrasonography to assess meniscal abnormalities in acute knees. J Knee Surg 2014;27:319-24.  Back to cited text no. 7
Miller TT. Sonography of injury of the posterior cruciate ligament of the knee. Skeletal Radiol 2002;31:149-54.  Back to cited text no. 8
Banu S, Sevgi IA, Seniz AY, Kubra U, Meral B. Comparison of the efficacy of physical therapy and corticosteroid injection in the treatment of pes anserine tendino-bursitis. J Phys Ther Sci 2016;28:1993-7.  Back to cited text no. 9
Geeslin AG, LaPrade RF. Surgical treatment of snapping medial hamstring tendons. Knee Surg Sports Traumatol Arthrosc 2010;18:1294-6.  Back to cited text no. 10


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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