Open the speculum slightly and lower it over a 10mm dilator.

Make sure that:

1. skin incision is at least 2.5 cm in length,
2. fascial incision is extended beyond the limits of the skin incision,
3. adequate finger dissection is performed before speculum insertion.

Speculum handle should point cranially or caudally during insertion to help clear skin and soft tissues.  When the speculum reaches the depth of the wound, the handle is turned 90 degrees to medial or lateral orientation before the blades are opened.

This is normal.  The speculum is used to expose the musculo-tendinous attachments to the bone.  These are then bipolar coagulated, divided with scissors and swept away from the bone.

This is normal.  Because the speculum blades do not flare, it will not be possible to get a pedicle-to-pedicle exposure with this device through a small incision.  That will be achieved later by the Spyder cranio-caudal blades. 

This is normal.  The speculum is primarily used to obtain cranio-caudal exposure spanning the facet joint.  Additional medial-lateral dissection can be performed after the cranio-caudal Spyder blades have been inserted.

This may occur if the patient is too thin.
Solutions:

1. Hold the speculum with one hand as you dissect with the other hand.
2. In very thin patients, the speculum is not needed, since the facet joint will be quite superficial.  Just use a Gelpi to hold the fascia open.

1. Select appropriate dilator for blade size.
2. Make sure retractor is completely closed.
3. Make sure the blades are not flared.

1. Incision should be at least 2.5 cm in length for smallest (16.5 mm) blades.  Consider extending the incision to fit larger blades or use smaller blades to fit into smaller incision.
2. Make sure retractor is completely closed.
3. Make sure the blades are not flared.

 

Causes and Solutions:

1. Limited by the skin incision: Not a problem. Only 5-6 mm of retractor opening is needed in a small incision.  The rest of the exposure will be obtained by flaring of the blades.
2. Limited by the fascial incision: Extend fascial incision well above and below the limits of skin incision.
3. Limited by bone:
   1. Use shorter blades to avoid getting caught between adjacent hypertrophic facet joints.
   2. Move the retractor slightly out of the wound, open the blades to clear facet joints and re-insert.

Causes and Solutions:

1. Limited by the fascial incision: Extend fascial incision well above and below the limits of skin incision.
2. Limited by bone:
   1. Use shorter blades to avoid getting caught between adjacent hypertrophic facet joints.
   2. Use unequal sized blades if the problem is only caudal or cranial.  At L5-S1, a shorter caudal blade works well.
   3. Move the retractor slightly out of the wound, flare the blades to clear facet joints, and re-insert.

Causes and Solutions:

1. One or both blades are too long: Use shorter blades. Consider unequal sized blades, especially at L5-S1, where the caudal blade can be shorter.
2. The blades haven’t cleared the hypertrophic facet joints and are sitting on top of the joints: Flare the blades more to clear the facet joints and then insert them deeper.

1. If there is a large amount of muscle, inadequate pre-dissection has been performed.  Return to the pre-dissection step.
2. A small amount of muscle attached to the bone along the perimeter of the exposure is a normal finding.  This is coagulated and detached from the bone.  The blades and unflared and re-flared to sweep the newly detached muscle out of the field of view.
3. As a shortcut, a small amount of muscle can be resected to obtain the necessary exposure.

Use lateral fluoroscopy to determine the location of the anatomical landmarks in relation to the cranial and caudal blades.

1. Pay attention to determination of exact pedicle locations by fluoroscopy before making the skin incision.
2. Un-tilt one blade and over-tilt the other blade.
3. Use a table attachment arm to re-center and stabilize the retractor.
4. Attach a blade insertion handle to one of the blades and have an assistant dynamically re-center and stabilize the retractor during the case.
5. Consider extending the incision.

1. Make sure an adequate fascial incision has been made cranially.
2. Flare the cranial blade more cranially.
3. Have the assistant move (translate) and hold the entire retractor complex slightly in a cranial direction.
4. Tilt the entire retractor complex cranially, using blade insertion handles or table attachment arm.
5. Consider extending the skin incision.

Causes and Solutions:

• The incision is too long: Use larger diameter tubular blades and open the retractor blades more.
• The retractor is sitting proud of the incision and is not sufficiently buried to be stabilized by the soft tissues: See previous section re correction of a proud-sitting retractor.

1. Open the cranial-caudal retractor more.
2. Use thinner medial-lateral blades.

 

The upper and lower retractor frames are different.  Make sure that the lower retractor frame is used for the cranio-caudal blades and the upper frame for the medial-lateral blades.

 

Causes and Solutions:

1. Limited by cranio-caudal blade edges:
   1. Open the cranio-caudal blades more.
   2. Use the thin pink blades or delta blades which require only 5-6 mm of separation between cranio-caudal blades.
2. Limited by bone: The medial blade may be hitting the slope of the lamina.  Use a shorter medial blade.
3. Limited by muscle:  The medial blade may be limited by the muscle mass trapped between it and the spinous process.  Perform a more extensive medial pre-dissection or resect some of this muscle.

Causes and Solutions:

1. Skin incision was made too laterally: The skin incision should have been made in the plane of the pedicles, not lateral to them as advocated in percutaneous techniques.  If it is expected that more than usual medial exposure is required for decompression, the skin incision can be planned along the medial edge of the pedicles based on AP fluoroscopy.  See below for solutions.
2. Finger dissection was carried out too laterally: Do not follow the cleavage plane between the multifidus and longissimus muscles. Finger dissection must be carried out within the multifidus muscle mass.
3. Solutions:
   1. Remove retractors.  Establish a more medial plane of dissection within multifidus, and reinsert retractors. (cumbersome)
   2. Resect some of the medial muscle mass.
   3. Tilt the entire retractor complex medially, using a table attachment arm or a blade inserter as a handle.

• Use table attachment arm to center the retractor more laterally.
• Resect some of the lateral muscle mass.
• Use a wider lateral blade and open/flare the retractor more.  This may require extension of skin and fascial incisions and a more thorough lateral pre-dissection.

 

Remove the medial-lateral retractor and use a hand-held retractor (e.g. Delta blade on a blade inserter).