Visualization of the surgical corridor | Retroperitoneal fat can creep into the field. | Fat in the field could obstruct visualization of the disc space and may result in injury to peritoneum or retroperitoneal contents. | Place the cut fingers of a number 9 glove over the retractor blades to create a expandable barrier (Figure 2). |
Anchoring the retractor | Difficult to test all 4 quadrants prior to shim placement. | Shim insertion without safe passage may injure neural structures. | Stimulate the posterior blade with t-EMG; next, use the black (initial) dilator to determine surrounding nerve proximity, and then insert the posterior shim over the black dilator (Figure 3). |
Retractor stability | Unrecognized ventral migration of the retractor will force the discectomy tools even more ventral. | Potential anterior implant placement or injuries to the vessels may occur. | Analyze the preoperative magnetic resonance imaging to evaluate the fat plane between the anterior longitudinal ligament (ALL) and the vessels. Use a Cobb elevator to develop this plane and placement of an ALL retractor. |
Surgeon ergonomics | Looking into the retractor during prone lateral procedures creates uncomfortable neck hyperextension. | Lack of ergonomics can cause long-term frustration or neck pain. | Rotating the bed 5° to 10° away from the surgeon creates a neutral neck position and optimizes visualization of the surgical corridor. |
High iliac crest | Iliac crest extending to the L4 pedicle can make it difficult to access the L4-L5 disc. | The downside retractor blade may block the angled instruments from optimal position. | A 90-mm caudal retractor blade allows for a circumferential retroperitoneal retraction without blocking the angled instruments. |