Distal Semimembranosus Injection

Other Names

• Distal Semimembranosus Tendon Peritendinous Injection
• Distal Semimembranosus Tendon Percutaneous Tenotomy

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Background

Semimembranosus is marked in yellow

Key Points

• Transducer: high frequency, linear
• Needle: 22-25 gauge for injection, 18-20 gauge for tenotomy
• Most easily performed long axis, in plane

Anatomy of the Semimembranosus muscle

• The muscle belly ends just proximal to the knee joint
• Main insertion is the infraglenoid tubercle of the posteromedial tibial plateau, posterior to MCL
• Inferior insertion occurs at the oblique popliteal ligament, posterior oblique ligament, fascia of popliteus
• Function as a knee flexor, internal rotation of tibia and hip extensor
• One of the three muscles of the hamstrings

Palpation Guidance vs Ultrasound Guidance

• There is no published data comparing ultrasound-guided vs palpation-guided injections of semiM
• Weiser followed 100 subjects after a palpation guided injection and found 58 subjects had long lasting relief and 30 subjects required a repeat injection after 3-5 months

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Indications

• Semimembranosus Tendinopathy

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

Transducer and needle position for peritendinous injection, short axis in plane

Ultrasound view of short axis, in plane peritendinous injection Needle is seen entering the semimembranosus

Transducer and needle position for percutaneous tenotomy, long axis in plane

Ultrasound view of long axis, in plane approach to tenotomy with needle vector marked by white arrow

Equipment

• Sterile prep (i.e. chloraprep, chlorhexidine, iodine, etc)
• Gloves
• Needle: typically 21-25 gauge, 1.5 inch
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• Transducer: high frequency, linear
• Evaluate in long and short axis
• Common ultrasound findings include:
  • Tendon thickening
  • Hypoechogenicity
  • Indistinct loosely packed fibrillar pattern

Peritendinous Injection: Long Axis, In Plane

• Patient Position
  • Prone or lateral decubitus
• Transducer position
  • Short axis to semimembranosus tendon
• Needle Approach/ Orientation
  • In plane
  • Medial-to-lateral
• Target
  • Peritendinous region of semimembranosus
• Pearls and Pitfalls
  • Avoid confusing semimembranosus with pes anserinus or MCL
  • Avoid confusing semimembranosus tendon with bakers cyst

Needle Tenotomy: Long Axis, In Plane

• Patient Position
  • Prone or lateral decubitus
• Transducer position
  • Long axis to semimembranosus tendon
• Needle Approach/ Orientation
  • In plane
  • Proximal-to-distal
• Target
  • Regions of abnormal tendon pathology
• Pearls and Pitfalls
  • Avoid confusing semimembranosus with pes anserinus or MCL
  • Avoid confusing semimembranosus tendon with bakers cyst

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Aftercare

• No major restrictions in most cases
• Can augment with ice, NSAIDS
• Consider Knee Compression Sleeve to reduce re-accumulation/ swelling

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Complications

• Infection
• Damage to surrounding tissue

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See Also

Internal

• Procedures Main
• Ultrasound Main
• Knee Pain Main

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