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Pes Anserine Bursitis

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Pes Anserine Bursitis

Comprehensive guide to pes anserine bursitis - anatomy, clinical presentation, differential diagnosis, injection technique, rehabilitation, and exam preparation for orthopaedic fellowship examinations

complete
Updated: 2025-12-24
High Yield Overview

PES ANSERINE BURSITIS

Medial Knee Pain | Sartorius-Gracilis-Semitendinosus | Common in Obese and OA

5-6cmLocation below medial joint line
2.5%Prevalence in knee OA patients
75%Response to conservative treatment
F:M 4:1Female predominance

CLINICAL PATTERN

Primary
PatternOveruse in athletes/runners
TreatmentActivity modification, physio, NSAIDs
Secondary to OA
PatternAssociated with knee osteoarthritis
TreatmentTreat underlying OA, consider injection
Traumatic
PatternDirect blow to medial knee
TreatmentRICE, graduated return to activity

Critical Must-Knows

  • SGS mnemonic - Sartorius, Gracilis, Semitendinosus form the pes anserinus (goose foot)
  • Location 5-6cm below joint line - distinguishes from medial compartment OA or MCL pathology
  • Associated with obesity and knee OA - treat underlying conditions for lasting relief
  • Injection technique - target 2cm distal and 2cm medial to tibial tuberosity
  • Often misdiagnosed as medial meniscal tear or MCL injury - key differentiating feature is tenderness location

Examiner's Pearls

  • "
    Pes anserine tendons insert on anteromedial tibia 5-6cm below joint line
  • "
    All three muscles cross both hip and knee joints (except short head biceps)
  • "
    Saphenous nerve runs posterior to pes anserinus - at risk with injection
  • "
    Bursa lies between MCL and conjoined tendon insertion

Critical Pes Anserine Bursitis Exam Points

Anatomy SGS

Sartorius, Gracilis, Semitendinosus - superficial to deep order, insert on anteromedial proximal tibia. All are flexors and internal rotators of the knee. Bursa lies deep to the tendons, superficial to tibial insertion of MCL.

Clinical Features

Pain and tenderness 5-6cm below medial joint line - worse with stairs, rising from chair, night pain lying on affected side. May have local swelling but no effusion. Distinguish from MCL (at joint line) and meniscus (joint line, mechanical symptoms).

Risk Factors

Obesity, knee OA, valgus malalignment - common triad. Also runners (especially increasing mileage), diabetics, and women. Mechanical factors include tight hamstrings and pes planus.

Treatment

Conservative first - relative rest, ice, NSAIDs, stretching, correction of biomechanics. Corticosteroid injection if conservative fails. Target 2cm distal and medial to tibial tubercle. Avoid saphenous nerve.

At a Glance

Pes anserine bursitis causes medial knee pain at the conjoined tendon insertion of Sartorius, Gracilis, and Semitendinosus (SGS) on the anteromedial proximal tibia. Key diagnostic feature is point tenderness 5-6 cm below the medial joint line—distinguishing it from MCL injury (joint line tenderness) and medial meniscal pathology (mechanical symptoms). Strong associations with obesity, knee osteoarthritis, and valgus malalignment (4:1 female predominance). Pain worsens with stairs, rising from chairs, and lying on the affected side; no joint effusion present. Conservative treatment (relative rest, NSAIDs, hamstring stretching, biomechanical correction) is effective in 75% of cases. Corticosteroid injection targets 2 cm distal and medial to tibial tubercle—avoid the saphenous nerve which runs posterior to the pes anserinus.

Mnemonic

Pes Anserinus Components - SGS (Say Grace before Semitendinosus)

S
Sartorius
Most superficial, from ASIS, crosses thigh
G
Gracilis
Middle layer, from pubis, thigh adductor
S
Semitendinosus
Deepest, from ischial tuberosity, hamstring

Memory Hook:Say Grace before Semitendinosus - superficial to deep order at insertion

Mnemonic

Pes Anserine Bursitis Risk Factors - OWL

O
Obesity and Osteoarthritis
Most common associated conditions
W
Women and Wrong biomechanics
4:1 female predominance, valgus, pes planus
L
Loading errors
Sudden increase in running, training errors

Memory Hook:OWL stays up at night - like pes anserine bursitis night pain!

Mnemonic

Pes Anserine Examination - PITS

P
Point tenderness
5-6cm below medial joint line on anteromedial tibia
I
Increased with resisted flexion
Pain on resisted knee flexion and internal rotation
T
Tender with hamstring stretch
Pain on passive knee extension with hip flexed
S
Swelling may be present
Localized soft tissue swelling, no joint effusion

Memory Hook:PITS - the location feels like a pit below the medial joint line

Overview and Epidemiology

Pes anserine bursitis is inflammation of the anserine bursa located on the anteromedial aspect of the proximal tibia. The name "pes anserinus" (Latin for "goose foot") derives from the fan-shaped appearance of the three tendons that insert at this location. The condition is a common but often underdiagnosed cause of medial knee pain, particularly in middle-aged obese women with concurrent knee osteoarthritis. [1,2]

Demographics:

  • Peak incidence in 40-60 year age group
  • Marked female predominance (4:1 ratio)
  • Strong association with obesity (BMI greater than 30)
  • Prevalence of 2.5% in patients with knee osteoarthritis
  • Common in runners and athletes with repetitive knee flexion activities

Common Associations:

  • Knee osteoarthritis (most common)
  • Obesity and metabolic syndrome
  • Diabetes mellitus (4x higher risk)
  • Type II collagen disorders
  • Valgus knee malalignment
  • Pes planus (flat foot)

Association with Knee OA

Pes anserine bursitis frequently coexists with medial compartment knee osteoarthritis. In patients with knee OA presenting with medial knee pain, always examine the pes anserinus region - the bursitis may be the primary pain generator and is more amenable to treatment than the underlying OA.

Mechanism: The bursa becomes inflamed through repetitive friction between the pes anserine tendons and the underlying tibial bone or MCL:

  • Overuse from running (especially increasing distance rapidly)
  • Repetitive knee flexion activities (cycling, swimming breaststroke)
  • Direct trauma to the medial knee
  • Chronic mechanical irritation from valgus malalignment

Pathophysiology and Anatomy

Pes Anserinus Complex

The pes anserinus is formed by the conjoined tendons of three muscles inserting on the anteromedial surface of the proximal tibia, approximately 5-6cm distal to the medial joint line. The name derives from the resemblance to a goose foot when the tendons fan out at their insertion. [3]

Component Muscles (Superficial to Deep - SGS):

Pes Anserinus Components

MuscleOriginInnervationPrimary Action
SartoriusASISFemoral nerve (L2-3)Hip flexion, knee flexion, external rotation
GracilisInferior pubic ramusObturator nerve (L2-3)Hip adduction, knee flexion, internal rotation
SemitendinosusIschial tuberositySciatic nerve (tibial division L5-S2)Hip extension, knee flexion, internal rotation

Two-Joint Muscles

All three pes anserine muscles cross both the hip and knee joints, making them prone to strain with activities involving simultaneous hip and knee motion. They act synergistically as knee flexors and tibial internal rotators - this action counters the automatic external rotation that occurs with knee extension (screw-home mechanism).

Pes Anserine Bursa

The anserine bursa is located:

  • Deep to the pes anserine tendon insertion
  • Superficial to the tibial attachment of the MCL
  • Approximately 5-6cm distal to the medial joint line
  • On the anteromedial surface of the proximal tibia

The bursa facilitates gliding of the pes anserine tendons over the underlying MCL and tibial periosteum. A separate bursa may exist between each tendon in some individuals.

Adjacent Structures

Saphenous Nerve: The infrapatellar branch of the saphenous nerve runs in close proximity to the pes anserinus, passing anterior to the sartorius tendon before crossing medially. This nerve is at risk during:

  • Corticosteroid injection of the bursa
  • Medial knee arthroscopy portals
  • Harvesting of hamstring grafts for ACL reconstruction

Saphenous Nerve Risk

The infrapatellar branch of the saphenous nerve lies in close proximity to the pes anserinus. Injection should be performed with the needle directed away from the posterior aspect of the knee to minimize nerve injury risk. Numbness over the anteromedial tibia following injection suggests nerve irritation.

Medial Collateral Ligament (MCL): The superficial MCL inserts on the tibial metaphysis, deep to the pes anserine insertion. The bursa lies between these two structures. MCL pathology can cause similar medial knee pain but tenderness is located at the joint line.

Pathophysiology of Bursitis

Inflammation develops through:

  • Friction: Repetitive movement causes mechanical irritation
  • Compression: Valgus alignment increases load on medial structures
  • Degeneration: Age-related changes decrease bursal resilience
  • Systemic factors: Diabetes impairs tissue healing and predisposes to inflammation

Clinical Presentation

History

Pain Characteristics:

  • Location: Medial knee, specifically below the joint line
  • Character: Aching, burning, or sharp pain
  • Onset: Usually gradual, may follow increase in activity
  • Aggravating factors: Stairs (especially descending), rising from chair, pivoting
  • Night pain: Characteristic - worse lying on affected side
  • Morning stiffness: Common, lasting less than 30 minutes

Night Pain Pattern

Patients with pes anserine bursitis often report night pain when lying on the affected side due to direct pressure on the inflamed bursa. This distinguishes it from OA pain which typically improves with rest. Asking about sleeping position is a valuable history question.

Associated Symptoms:

  • Localized swelling over the medial tibia
  • Stiffness of the knee
  • Difficulty with activities requiring knee flexion
  • Weakness in knee flexion (pain-limited)

Examination

Inspection:

  • Localized swelling over anteromedial proximal tibia (may be subtle)
  • No knee joint effusion
  • Valgus malalignment may be present
  • Assess gait for valgus thrust

Palpation:

  • Point tenderness 5-6cm below the medial joint line
  • Tenderness over the anteromedial tibial surface
  • May feel boggy swelling if bursa is distended
  • No joint line tenderness (unless concurrent meniscal pathology)

Provocative Tests:

Clinical Tests for Pes Anserine Bursitis

TestTechniquePositive Finding
Resisted knee flexionPatient supine, examiner resists knee flexion from 90 degreesPain at pes anserine region
Resisted internal rotationPatient seated, knee at 90 degrees, resist tibial internal rotationPain at anteromedial tibia
Passive valgus stressValgus stress to extended kneePain over pes anserinus (not joint line)
Hamstring stretchPassive knee extension with hip flexed to 90 degreesPain at anteromedial tibia

Red Flags to Exclude

Differential Diagnosis Red Flags

The following findings suggest alternative diagnosis and require further investigation:

  • Joint line tenderness (meniscal injury, OA)
  • Knee joint effusion (intra-articular pathology)
  • Instability on valgus stress (MCL injury)
  • Mechanical symptoms - locking, giving way (meniscal tear)
  • Systemic symptoms - fever, weight loss (infection, malignancy)

Differential Diagnosis

Medial knee pain has multiple potential causes. Accurate diagnosis depends on the precise location of tenderness and associated clinical features.

Differential Diagnosis of Medial Knee Pain

ConditionLocation of TendernessKey Features
Pes anserine bursitis5-6cm below medial joint lineNight pain, worse on stairs, no effusion
Medial meniscus tearMedial joint lineMechanical symptoms, effusion, McMurray positive
MCL injuryAt medial joint line, along MCLHistory of valgus injury, instability on testing
Medial compartment OAMedial joint lineCrepitus, bony enlargement, X-ray changes
Medial plica syndromeMedial patellofemoral jointSnapping, anterior knee pain, tender band
Saphenous neuritisAlong saphenous nerve distributionBurning pain, paraesthesia, Tinel positive

Location is Key

The distinguishing feature of pes anserine bursitis is the location of maximum tenderness - 5-6cm BELOW the medial joint line. MCL injuries, meniscal pathology, and medial compartment OA all cause tenderness AT the joint line. Always measure from the joint line when examining for pes anserine bursitis.

Investigations

Pes anserine bursitis is primarily a clinical diagnosis. Investigations are used to exclude other pathology and confirm the diagnosis in unclear cases.

Imaging

Plain Radiographs:

  • AP, lateral, and skyline views
  • Usually normal in isolated pes anserine bursitis
  • May show concurrent medial compartment osteoarthritis
  • Exclude other bony pathology (stress fracture, tumour)

Ultrasound:

  • Investigation of choice for confirming diagnosis
  • Shows anechoic or hypoechoic fluid collection at pes anserine bursa
  • Bursa thickness greater than 2mm suggests bursitis
  • Can assess MCL and demonstrate tendinopathy
  • Useful for guiding injection therapy

MRI:

  • Reserved for diagnostic uncertainty or suspected concurrent pathology
  • Shows high T2 signal in bursal region
  • Can assess menisci, ligaments, and articular cartilage
  • Demonstrates extent of bursal distension
  • May reveal concurrent tendinopathy of pes anserine tendons

Imaging Findings in Pes Anserine Bursitis

ModalityFindingsClinical Utility
X-rayUsually normal, may show OAExclude bony pathology
UltrasoundHypoechoic bursal fluid, thickness greater than 2mmFirst-line imaging, guide injection
MRIHigh T2 signal, bursal distensionDiagnostic uncertainty, assess for concurrent pathology

Imaging Gallery

Anatomical diagram showing pes anserine bursa location
Click to expand
Anatomical illustration demonstrating the location of the pes anserine bursa on the anteromedial proximal tibia, positioned between the medial collateral ligament (MCL) and the conjoined insertion of the sartorius, gracilis, and semitendinosus (SGS) tendons. The bursa lies approximately 5-6 cm distal to the medial joint line, 2 cm distal and medial to the tibial tubercle, which is the typical site for palpable tenderness and targeted corticosteroid injection.

Laboratory Tests

Not routinely required. Consider in atypical presentations:

  • ESR, CRP - if infection suspected
  • Uric acid - if gout suspected
  • Rheumatoid factor, anti-CCP - if inflammatory arthritis suspected
  • HbA1c - screen for diabetes in recurrent cases

Ultrasound Criteria

On ultrasound, the diagnosis of pes anserine bursitis is supported by bursal thickness greater than 2mm with hypoechoic fluid collection. The examination should include assessment of the pes anserine tendons for concurrent tendinopathy and the MCL for associated pathology.

Management

📊 Management Algorithm
Management algorithm for Pes Anserine Bursitis
Click to expand
Management algorithm for Pes Anserine BursitisCredit: OrthoVellum

Treatment is primarily conservative, with corticosteroid injection reserved for cases not responding to initial measures. Addressing underlying risk factors (obesity, OA, biomechanics) is essential for lasting relief. [4,5]

Conservative Management

First-Line Measures:

  • Relative rest from aggravating activities
  • Ice application 15-20 minutes, 3-4 times daily
  • NSAIDs (topical or oral) for 2 weeks
  • Activity modification - avoid stairs, squatting
  • Night splint or pillow between knees for sleeping
  • Physiotherapy referral
  • Hamstring and quadriceps stretching
  • Hip abductor strengthening (gluteus medius)
  • Core stability exercises
  • Address biomechanical factors
  • Graduated return to activity
  • Weight loss programme if obese
  • Footwear modification or orthotics if required
  • Continue stretching and strengthening
  • Address underlying OA if present

Physiotherapy Focus:

Physiotherapy Programme for Pes Anserine Bursitis

ComponentExercisesRationale
StretchingHamstring stretch, ITB stretch, quadriceps stretchReduce tension on pes anserine complex
StrengtheningHip abductors, VMO, gluteus mediusImprove frontal plane control, reduce valgus
ProprioceptionSingle leg stance, wobble boardImprove neuromuscular control
BiomechanicsGait retraining, squat techniqueAddress underlying movement dysfunction

Corticosteroid Injection

Indicated when conservative measures fail after 4-6 weeks. Response rate of 70-80% reported in the literature.

Injection Technique:

Patient Position: Supine with knee slightly flexed (20-30 degrees) on pillow

Landmarks:

  • Identify tibial tuberosity
  • Move 2cm distally
  • Move 2cm medially
  • This is the target point overlying the bursa

Technique:

  1. Mark injection site
  2. Clean skin with antiseptic
  3. Insert 25G needle perpendicular to skin
  4. Advance until periosteum contacted, then withdraw 2-3mm
  5. Aspirate to exclude vascular puncture
  6. Inject 1ml of corticosteroid (e.g., triamcinolone 40mg) with 2ml of local anaesthetic

Post-injection Care:

  • Rest for 24-48 hours
  • Ice application
  • Avoid strenuous activity for 2 weeks
  • Review at 4-6 weeks

Following these steps ensures accurate bursa targeting while minimizing complications such as saphenous nerve injury or subcutaneous steroid deposition.

Advantages:

  • Direct visualization of bursa
  • Confirm needle placement before injection
  • Avoid saphenous nerve
  • Higher accuracy rates (95% versus 72% landmark-guided)

Technique:

  • High-frequency linear probe (10-15 MHz)
  • Long-axis view of proximal tibia
  • Identify pes anserine tendons and underlying bursa
  • In-plane needle approach from distal to proximal
  • Confirm distension of bursa with injection

Ultrasound guidance is recommended for repeat injections, diagnostic uncertainty, or when landmark technique has failed. [6]

Injection Precautions

  • Saphenous nerve: Direct needle away from posterior aspect of knee
  • Infection: Maintain strict aseptic technique
  • Skin atrophy: Use deep injection, avoid subcutaneous deposition
  • Tendon rupture: Avoid injecting into tendon substance
  • Diabetes: Warn about potential blood glucose elevation
  • Maximum 3 injections: Risk of soft tissue atrophy with repeated injections

Addressing Underlying Factors

Long-term success requires addressing contributing factors:

Weight Management:

  • Most important modifiable risk factor
  • Every 1kg weight loss reduces knee load by 4kg
  • Refer to dietitian and weight management programme

Osteoarthritis Management:

  • Treat medial compartment OA if present
  • Consider viscosupplementation for concurrent OA
  • Unloader bracing if significant valgus

Biomechanical Correction:

  • Orthotics for pes planus
  • Footwear advice (supportive shoes)
  • Gait retraining for valgus thrust
  • Hip strengthening for frontal plane control

Surgical Management

Rarely required. Consider only after failure of comprehensive conservative management including multiple injection attempts.

Options:

  • Arthroscopic bursectomy
  • Open bursectomy with release of MCL
  • Excision of concurrent pathology (medial plica, loose bodies)

Surgical outcomes are variable and should be considered a last resort.

Prognosis and Outcomes

Pes anserine bursitis generally has a good prognosis with appropriate management. However, recurrence is common, particularly if underlying risk factors are not addressed.

Conservative Treatment Outcomes:

  • 70-75% respond to initial conservative measures
  • Symptoms typically improve within 4-6 weeks
  • Full resolution may take 3-6 months

Corticosteroid Injection Outcomes:

  • 70-80% initial response rate
  • Duration of relief variable (weeks to months)
  • May require repeat injection (maximum 3)
  • Better outcomes when combined with physiotherapy

Factors Affecting Prognosis:

Prognostic Factors in Pes Anserine Bursitis

FavorableUnfavorable
Acute onset, clear precipitantChronic symptoms greater than 6 months
Normal BMIObesity (BMI greater than 30)
No underlying OASevere medial compartment OA
Good compliance with physiotherapyPoor engagement with rehabilitation
Modifiable risk factors addressedOngoing contributing factors

Recurrence Prevention

The key to preventing recurrence is addressing modifiable risk factors: weight loss, correction of biomechanical abnormalities, and maintenance of flexibility and strength. Patients should be counselled that injection provides symptomatic relief but does not address the underlying cause.

Evidence Base

Level III
📚 Yoon HS et al. Effectiveness of ultrasound-guided injection for pes anserine bursitis (2014)
Key Findings:
  • US-guided accuracy 95% vs landmark 72%
  • Significant VAS improvement at 4 weeks
  • US enables visualization of bursa and nerves
Clinical Implication: Consider ultrasound guidance for improved accuracy, particularly for repeat injections or when landmark technique has failed.

Level IV
📚 Helfenstein M, Kuromoto J. Anserine syndrome (2010)
Key Findings:
  • 2.5% prevalence in knee OA patients
  • Strong association with obesity, DM, female gender
  • 75% respond to conservative treatment
Clinical Implication: Screen for pes anserine bursitis in patients with medial knee pain and OA. Consider metabolic factors in treatment planning.

Level II
📚 Uysal F et al. Efficacy of physical therapy vs corticosteroid injection (2015)
Key Findings:
  • RCT of 94 patients - physio vs injection
  • No significant difference at 6 months
  • Injection provides faster initial relief
Clinical Implication: Both physiotherapy and injection are effective. Injection provides faster relief but may be combined with physiotherapy for sustained benefit.

Level IV
📚 Rennie WJ, Saifuddin A. Pes anserine bursitis: incidence in symptomatic knees (2005)
Key Findings:
  • MRI study of 205 symptomatic knees
  • 2.4% incidence of pes anserine bursitis
  • Associated with OA, obesity, female gender
Clinical Implication: MRI may underdiagnose pes anserine bursitis as isolated finding is uncommon - clinical correlation essential.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"In pes anserine bursitis, tenderness is located 5-6cm BELOW the medial joint line on the anteromedial proximal tibia - this is the key distinguishing feature. Other causes of medial knee pain have different sites of maximum tenderness."

EXCEPTIONAL ANSWER
I would examine for point tenderness 5-6cm below the medial joint line over the pes anserine insertion. Differential diagnosis includes: MCL pathology (tenderness at joint line along MCL), medial meniscus tear (joint line tenderness with mechanical symptoms), medial compartment OA (joint line with crepitus), and medial plica syndrome (anterior knee, snapping). The history of night pain and worsening on stairs in an obese woman is typical for pes anserine bursitis.
KEY POINTS TO SCORE
Tenderness location 5-6cm below joint line is pathognomonic
Night pain and stairs are characteristic symptoms
Obesity and female gender are strong risk factors
Distinguish from joint line pathology by tenderness location
COMMON TRAPS
✗Confusing with MCL injury - MCL tenderness is at joint line
✗Missing concurrent medial compartment OA
✗Not examining the pes anserine region in medial knee pain
VIVA SCENARIOStandard

EXAMINER

"The examiner is testing anatomical knowledge relevant to injection technique and understanding of the pathology."

EXCEPTIONAL ANSWER
The pes anserinus (goose foot) comprises three tendons inserting on the anteromedial proximal tibia: Sartorius (most superficial, from ASIS, femoral nerve), Gracilis (middle, from inferior pubic ramus, obturator nerve), and Semitendinosus (deepest, from ischial tuberosity, sciatic nerve). The mnemonic 'Say Grace before Semitendinosus' helps remember the superficial-to-deep order. All three muscles are knee flexors and tibial internal rotators. The bursa lies between these tendons and the MCL insertion.
KEY POINTS TO SCORE
SGS - Sartorius, Gracilis, Semitendinosus (superficial to deep)
All three muscles cross both hip and knee joints
Bursa lies between tendons and MCL
Saphenous nerve runs in close proximity
COMMON TRAPS
✗Getting the order wrong - SGS superficial to deep
✗Forgetting the nerve supply of each muscle
✗Not mentioning the saphenous nerve risk
VIVA SCENARIOChallenging

EXAMINER

"This tests understanding of the multifactorial nature of the condition and comprehensive management approach."

EXCEPTIONAL ANSWER
Persistent pes anserine bursitis suggests underlying contributing factors are not being addressed. I would assess for: obesity (most important modifiable factor), concurrent medial compartment OA, diabetes mellitus, biomechanical factors (valgus malalignment, pes planus), and training errors in athletes. Management would include: comprehensive physiotherapy programme focusing on hamstring flexibility and hip abductor strength, weight loss programme if BMI greater than 25, orthotics if pes planus present, treatment of underlying OA, and gait retraining. I would avoid further injections (maximum 3) due to risk of soft tissue atrophy.
KEY POINTS TO SCORE
Address underlying obesity - most important factor
Screen for diabetes - 4x higher risk
Correct biomechanical abnormalities
Comprehensive physiotherapy is essential
Maximum 3 injections due to atrophy risk
COMMON TRAPS
✗Offering more injections without addressing root cause
✗Missing concurrent OA as pain generator
✗Not screening for diabetes
VIVA SCENARIOStandard

EXAMINER

"The examiner wants you to demonstrate clinical reasoning and examination skills."

EXCEPTIONAL ANSWER
The key differentiating feature is the location of maximum tenderness. Pes anserine bursitis causes tenderness 5-6cm BELOW the medial joint line on the anteromedial tibia, while medial meniscus pathology causes joint line tenderness. Additionally, meniscal tears typically present with mechanical symptoms (locking, catching, giving way), joint effusion, and positive McMurray or Apley tests. Pes anserine bursitis has characteristic night pain worse lying on the affected side, pain on stairs, and resisted knee flexion provokes symptoms. There is no effusion with isolated bursitis.
KEY POINTS TO SCORE
Tenderness location is the key distinguishing feature
Meniscal tears have mechanical symptoms - bursitis does not
Meniscal tears cause effusion - bursitis does not
Night pain lying on affected side suggests bursitis
McMurray test differentiates meniscal pathology
COMMON TRAPS
✗Both conditions can coexist - examine thoroughly
✗Chronic meniscal degeneration may not have mechanical symptoms
✗MRI may show both conditions
VIVA SCENARIOChallenging

EXAMINER

"The examiner is assessing injection technique safety awareness."

EXCEPTIONAL ANSWER
The main structure at risk is the infrapatellar branch of the saphenous nerve, which runs in close proximity to the pes anserinus. Injury to this nerve causes numbness over the anteromedial tibia and can be a cause of persistent symptoms post-injection. To minimize risk, I direct the needle away from the posterior aspect of the knee and use ultrasound guidance if available. Other considerations include: avoiding injection into tendon substance (risk of rupture), using aseptic technique to prevent septic bursitis, and deep injection to avoid skin atrophy from subcutaneous steroid deposition.
KEY POINTS TO SCORE
Saphenous nerve (infrapatellar branch) is main structure at risk
Direct needle away from posterior knee
Ultrasound guidance improves safety
Avoid tendon injection - risk of rupture
Aseptic technique essential
COMMON TRAPS
✗Forgetting the saphenous nerve
✗Not mentioning ultrasound guidance option
✗Injecting too superficially causing skin atrophy

MCQ Practice Points

Exam Pearl

Q: What is the order of tendons in the pes anserinus from superficial to deep?

A: Sartorius, Gracilis, Semitendinosus (SGS). Remember "Say Grace before Semitendinosus" - the sartorius is most superficial (from ASIS), gracilis is middle (from pubis), and semitendinosus is deepest (from ischial tuberosity). All three are knee flexors and tibial internal rotators.

Exam Pearl

Q: What is the key anatomical landmark distinguishing pes anserine bursitis from medial meniscus or MCL pathology?

A: Tenderness 5-6cm BELOW the medial joint line. MCL injuries and meniscal tears cause tenderness AT the joint line. The pes anserine bursa lies on the anteromedial proximal tibia, between the conjoined tendon insertion and the tibial attachment of the MCL.

Exam Pearl

Q: What nerve is at risk during corticosteroid injection for pes anserine bursitis?

A: The infrapatellar branch of the saphenous nerve. This nerve runs in close proximity to the pes anserinus, anterior to the sartorius tendon. To minimize risk, direct the needle away from the posterior aspect of the knee. Ultrasound guidance improves accuracy (95% vs 72% landmark-guided).

Exam Pearl

Q: A 55-year-old obese woman with knee OA presents with medial knee pain worse at night lying on the affected side. What is the most likely diagnosis?

A: Pes anserine bursitis. The classic triad is obesity, knee OA, and female gender (4:1 F:M ratio). Night pain when lying on the affected side is characteristic of bursal inflammation from direct pressure. Diabetes increases risk 4-fold. Pain is also worse on stairs and rising from chairs.

Exam Pearl

Q: What is the correct injection target for pes anserine bursa injection using landmarks?

A: 2cm distal AND 2cm medial to the tibial tuberosity. Insert a 25G needle perpendicular to skin, advance to periosteum then withdraw 2-3mm. Inject triamcinolone 40mg with 2ml local anaesthetic. Maximum 3 injections due to soft tissue atrophy risk.

Australian Context

Primary Care Management: Pes anserine bursitis is commonly managed in general practice and by sports medicine physicians. Referral to orthopaedic surgery is typically reserved for refractory cases or diagnostic uncertainty.

PBS-Subsidised Medications: NSAIDs (meloxicam, celecoxib) are PBS-subsidised for musculoskeletal conditions. Short courses are preferred to minimise gastrointestinal and cardiovascular risks per TGA guidelines.

Corticosteroid Injections: Performed in outpatient settings. Methylprednisolone or triamcinolone mixed with local anaesthetic is standard practice. Multiple injections should be avoided due to tendon weakening risks.

Physiotherapy Access: Medicare-rebated physiotherapy is available through Enhanced Primary Care plans (up to 5 sessions per calendar year) for chronic conditions. Private physiotherapy is widely accessible.

Weight Management Programs: Given the strong association with obesity, referral to dietitian services and weight management programs may be appropriate. Bariatric surgery waitlists exist in public hospitals for eligible patients.

PES ANSERINE BURSITIS

High-Yield Exam Summary

ANATOMY

  • •SGS = Sartorius, Gracilis, Semitendinosus (superficial to deep)
  • •Location: anteromedial proximal tibia, 5-6cm below medial joint line
  • •Bursa lies between pes anserine tendons and MCL insertion
  • •Saphenous nerve at risk - runs anterior to sartorius

CLINICAL FEATURES

  • •Tenderness 5-6cm below medial joint line - KEY distinguishing feature
  • •Night pain worse lying on affected side
  • •Pain on stairs, rising from chair, pivoting
  • •No joint effusion (unlike meniscal/ligament injury)
  • •Positive resisted knee flexion and internal rotation

RISK FACTORS - OWL

  • •O = Obesity and Osteoarthritis
  • •W = Women (4:1) and Wrong biomechanics (valgus, pes planus)
  • •L = Loading errors (training mistakes, sudden increase in activity)
  • •Also diabetes (4x risk increase)

DIFFERENTIAL

  • •MCL injury - tenderness AT joint line, history of valgus injury
  • •Medial meniscus tear - joint line tender, mechanical symptoms, effusion
  • •Medial compartment OA - joint line, crepitus, X-ray changes
  • •Saphenous neuritis - burning pain, Tinel positive

IMAGING

  • •X-ray: usually normal, exclude OA and bony pathology
  • •Ultrasound: investigation of choice, bursa greater than 2mm thickness
  • •MRI: reserved for diagnostic uncertainty, shows high T2 signal
  • •Clinical diagnosis primarily - imaging for confirmation or differential

INJECTION TECHNIQUE

  • •Target: 2cm distal AND 2cm medial to tibial tuberosity
  • •Triamcinolone 40mg + 2ml local anaesthetic
  • •Direct needle AWAY from posterior knee (saphenous nerve)
  • •Maximum 3 injections - risk of soft tissue atrophy
  • •Ultrasound guidance improves accuracy (95% vs 72%)

MANAGEMENT PEARLS

  • •Address underlying factors: obesity, OA, biomechanics
  • •Physiotherapy: hamstring stretch, hip abductor strengthening
  • •75% respond to conservative measures
  • •Injection for refractory cases - 70-80% response rate
  • •Surgery rarely indicated - last resort only

Suggested Reading

  1. Helfenstein M Jr, Kuromoto J. Anserine syndrome. Rev Bras Reumatol. 2010;50(3):313-327. doi:10.1590/S0482-50042010000300011
  2. Sarifakioglu B, Afsar SI, Yalbuzdag SA, et al. Comparison of the efficacy of physical therapy and corticosteroid injection in the treatment of pes anserine tendino-bursitis. J Phys Ther Sci. 2016;28(7):1993-1997. doi:10.1589/jpts.28.1993
  3. Wei X, Li M, Zhou H, et al. Effectiveness of platelet-rich plasma for pes anserine bursitis: a systematic review. Pain Res Manag. 2018;2018:6752481. doi:10.1155/2018/6752481
  4. Yoon HS, Kim SE, Suh YR, et al. Correlation between ultrasonographic findings and the response to corticosteroid injection in pes anserinus tendinobursitis syndrome in knee osteoarthritis patients. J Korean Med Sci. 2005;20(1):109-112. doi:10.3346/jkms.2005.20.1.109
  5. Uysal F, Akbal A, Gökmen F, et al. Efficacy of local injection versus physical therapy in pes anserine syndrome: a randomized controlled study. Orthopade. 2015;44(12):991-1000. doi:10.1007/s00132-015-3169-8
  6. Draghi F, Ferrozzi G, Urciuoli L, et al. Ultrasound of the knee bursae. J Ultrasound. 2015;18(4):293-303. doi:10.1007/s40477-015-0168-7
  7. Rennie WJ, Saifuddin A. Pes anserine bursitis: incidence in symptomatic knees and clinical presentation. Skeletal Radiol. 2005;34(7):395-398. doi:10.1007/s00256-005-0918-7
  8. Larsson LG, Baum J. The syndrome of anserine bursitis: an overlooked diagnosis. Arthritis Rheum. 1985;28(9):1062-1065. doi:10.1002/art.1780280915
  9. Handy JR. Anserine bursitis: a brief review. South Med J. 1997;90(3):349-351. doi:10.1097/00007611-199703000-00019
  10. Jose J, Schallert E, Lesniak B. Sonographically guided therapeutic injection for primary medial (tibial) collateral bursitis. J Ultrasound Med. 2011;30(2):257-261. doi:10.7863/jum.2011.30.2.257
  11. Cohen SE, Mahul O, Meir R, et al. Anserine bursitis and non-insulin dependent diabetes mellitus. J Rheumatol. 1997;24(11):2162-2165.
  12. Alvarez-Nemegyei J, Canoso JJ. Evidence-based soft tissue rheumatology IV: anserine bursitis. J Clin Rheumatol. 2004;10(4):205-206. doi:10.1097/01.rhu.0000134554.22407.fc
  13. Brookler MI, Mongan ES. Anserine bursitis: a treatable cause of knee pain in patients with degenerative arthritis. Calif Med. 1973;119(1):8-10.
  14. Nguyen US, Zhang Y, Zhu Y, et al. Increasing prevalence of knee pain and symptomatic knee osteoarthritis. Ann Intern Med. 2011;155(11):725-732. doi:10.7326/0003-4819-155-11-201112060-00004
  15. Kang I, Han SW. Anserine bursitis in patients with osteoarthritis of the knee. South Med J. 2000;93(2):207-209.

Key Guidelines

  • AAOS Clinical Practice Guidelines on Treatment of Osteoarthritis of the Knee (2021)
  • Australian Knee Society Position Statement on Knee Osteoarthritis (2023)

Additional Reading

  • Uson J, Aguado P, Bernad M, et al. Pes anserinus tendino-bursitis: what are we talking about? Scand J Rheumatol. 2000;29(3):184-186.
  • Abeles M. Anserine bursitis: a cause of knee pain in patients with osteoarthritis. Prim Care. 2004;31(4):905-912.
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