The overall goal of this method is to introduce a safe, effective, and well-tolerated technique of muscle biopsy of the vastus lateralis, to obtain sufficient tissue for histochemistry and molecular analysis in both diagnostic and research studies. This method can help investigators obtain sufficient muscle tissue with minimal discomfort and trauma for the participant. The main advantage of this technique is that it's safe and acceptable in both clinical and research settings.
Complications are low, and discomfort's kept to a minimum when the procedure is performed using a standard technique. To begin, ask the participant to lie comfortably on a couch in a supine position. Expose the preferred thigh from the groin crease, and spread a disposable absorbent sheet under the exposed thigh.
Ensure that the leg remains straight and relaxed throughout the procedure, but the thigh is tensed momentarily to outline the vastus lateralis. Mark the procedure site approximately 2/3 down an imaginary line from the anterior superior iliac spine to the patella. To prepare the skin, use a sterile shaving blade to shave approximately four centimeters in diameter surrounding the proposed biopsy site, in men, if required.
Use an alcohol swab to clean the skin. Use a local anesthetic to infiltrate the skin and overlying fascia, then, with a 25-gauge needle, raise a subcutaneous bleb of 2%lidocaine. Next, use a 23-gauge needle to infiltrate deeper into the subcutaneous tissue, aiming to penetrate at least 1/2 an inch, depending on the subcutaneous content at the biopsy site.
Allow two to five minutes for the anesthesia to take action, and confirm anesthesia by using a needle or scalpel blade tip to gently probe the skin. To prepare a sterile field, wash hands with soap and water, and maintain clean hands until a sterile gown is worn. Cover hands with sterile gloves before creating a sterile field on the procedure trolley.
With 2%Chlorhexidine isopropyl alcohol solution, or an iodine-based skin disinfectant, sterilize the biopsy site. Apply a sterile drape with an adhesive aperture to expose the biopsy site and to maintain a sterile field. The first critical step is to puncture the skin and make a sufficiently deep track into and beyond the fascia.
To perform the biopsy procedure, with a size 11 scalpel, make a five to 10 millimeter incision on the skin, and in through the overlying fascia. While holding and supporting the thigh surrounding the biopsy site, insert the closed biting tip of the conchotome through the incision, at a right angle to the long axis of the femur, approximately 1/2 to one inch deep. Next, rotate the conchotome from 90 to 180 degrees to cut the muscle, then withdraw the conchotome and open the tip onto sterile gauze dampened by sterile normal saline.
Transfer the gauze into a container placed on ice. The second critical step is to insert the conchotome within the track, to maneuver the conchotome to ensure sufficient muscle has been obtained. If necessary, the procedure can be repeated within the track, and single wound site to obtain sufficient muscle tissue.
Following the procedure, apply direct pressure to the wound for up to five minutes. Then place sterile strips parallel to the wound to close it. Place a sterile absorbent dressing on the Steri-Strips, and apply a two-layer bandage for compression, using tape to secure.
Explain the wound dressing method to the participant for them to perform three to four days after the procedure. Instruct the participant to remove the compression bandage before going to bed later that evening. Explain that it is common to experience some thigh stiffness, which can be relieved by gentle exercise, such as walking.
Explain that they can use acetaminophen for the pain. As shown in this table, in the Hertfordshire sarcopenia study, the pain score is measured using the pain Visual Analogue Scale of zero millimeters for no pain, to 100 millimeters to pain as bad as can be, were typically low, with a median of seven millimeters during the procedure, and four millimeters one day after the procedure. This suggests that the subjects in this research study found the procedure minimally painful.
Shown here are representative tissue samples obtained through percutaneous muscle biopsy with the Weil-Blakesley conchotome. The samples obtained should resemble the muscle tissue in this panel. However, there is a high probability of obtaining subcutaneous fatty tissue, as seen in this panel.
This figure shows a serial cross section with differential fiber staining. Darkly stained fibers represent type two fast fibers detected with an anti-myosin fast antibody. Once mastered, this technique can be done in 20 minutes, if it is performed properly.
While attempting this procedure, it's important to remember to maintain a sterile field, and keep the participant engaged. Following this procedure, other methods like histochemistry and DNA or RNA extraction can be performed, and all that will answer additional questions, like what are the cellular and molecular changes that occur in aging muscle? After its development, this technique paved way for researchers in the field of muscle biology and aging, to explore the changes in muscle tissue with sarcopenia, the age-related decline of muscle mass and function.
After watching this video, you should have a good understanding of how to perform a muscle biopsy of the vastus lateralis, using the Weil-Blakesley conchotome, a simple, effective, and well-tolerated procedure. Don't forget that working with sharp needles and instruments can be hazardous, and standard safety precautions as well as strict asepsis should always be maintained while performing this procedure.
