Sonographically Guided Semimembranosus Bursa Injection: Technique and Validation

Area of Science:

• Musculoskeletal Imaging
• Anatomy
• Injection Techniques

Background:

• The semimembranosus (SM) bursa is a common site for knee pain, often requiring accurate diagnostic or therapeutic injections.
• Sonographic guidance (SG) offers potential for precise needle placement in deep anatomical structures.
• Cadaveric models are crucial for validating novel procedural techniques without patient risk.

Purpose of the Study:

• To describe and validate a sonographically guided (SG) injection technique for the semimembranosus (SM) bursa.
• To assess the accuracy and safety of SG SM bursa injections in an unembalmed cadaveric model.

Main Methods:

• A prospective, cadaveric laboratory investigation was conducted using 10 unembalmed human lower limb specimens.
• An experienced operator performed SG SM bursa injections using 3 mL of colored latex.
• Specimens were dissected after a minimum of 2 days to evaluate latex distribution and identify any neurovascular injury.

Main Results:

• All 10 injections (100%) accurately placed latex within the SM bursa, with proximal spread to the knee joint level.
• Eighty percent (80%) of injections showed minimal (<1 mL) extrabursal flow, without intra-articular extension.
• No instances of neurovascular injury were observed during the dissection phase.

Conclusions:

• Sonographically guided (SG) injections into the semimembranosus (SM) bursa are feasible and accurate in a cadaveric model.
• This technique shows promise for diagnostic and therapeutic applications in patients with suspected distal SM disorders.
• Consideration of injection volumes less than 3 mL may help minimize extrabursal spread.