Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.

Study Design. Retrospective case series. Objective. To report on the rare finding of motor deficits contralateral to the transpsoas approach in patients who underwent lateral lumbar interbody fusion (LLIF). Summary of Background Data. Although sensorimotor deficits occurring ipsilaterally to a transpsoas approach have more fully been elucidated, there seems to be a paucity of data on motor deficits contralateral to an LLIF approach. Methods. The electronic medical records and radiographical studies of 244 patients who underwent LLIF at a single institution between 2006 and 2009 were retrospectively reviewed for reports on motor deficits contralateral to the surgical approach. Results. Of the patients reviewed, 2.9% (7/244) presented with a postoperative contralateral motor deficit, the most severe of which was a 1/5 weakness of the quadriceps muscle. An average of 3 levels (range: 2–4) was fused in 7 patients who developed a contralateral motor deficit, and in 3 of the 7 patients, an anterior lumbar interbody fusion (ALIF) was performed in addition to the LLIF. At 1 year follow-up, 3 patients presented with complete resolution of their muscle weakness, 1 patient still had mild weakness, 1 patient had decreased range of motion in the affected joint, and 1 patient had a 2/5 foot drop. One patient was lost to follow-up. Conclusion. These data are among the largest reports of contralateral motor deficits after LLIF. Among possible underlying mechanisms are entrapment of the contralateral nerve root through translational correction of spondylolisthesis, front-to-back misalignment of the cage resulting in contralateral nerve root impingement, pressure on the contralateral peroneal nerve during positioning, and overdistraction neurapraxia when using ALIF at L5–S1 concomitantly. Awareness of the possibility of this rare complication can play an important role in surgical consideration and preoperative patient counseling. Level of Evidence: 4

Study Design. Prospective in vivo radiation exposure study. Objective. To assess surgeon exposure to ionizing radiation in the setting of lateral lumbar interbody fusion (LLIF). Summary of Background Data. Minimally invasive spine surgery relies heavily on image guidance. Rapid popularization of minimally invasive spine surgery procedures, such as LLIF, is appropriately accompanied by concern regarding occupational radiation exposure related to intraoperative fluoroscopy. Methods. Optically stimulated luminescence technology dosimeters were used to record radiation exposure prospectively at 5 anatomic locations during 18 LLIF procedures: (1) eye, (2) thyroid, (3) chest, (4) axilla, and (5) gluteal region. Additionally, a ring dosimeter was worn during 13 of the LLIF cases. Results. Average fluoroscopy time was 88.7 ± 36.8 seconds and skin dose to the patient was 25.2 ± 21.1 mGy. The chest dosimeter protected by lead recorded the lowest readings per procedure (0.44 ± 0.49 mrem). The gluteal dosimeter recorded an average exposure of 2.31 ± 4.50 mrem and the dosimeter at the axilla recorded an average of 4.20 ± 7.76 mrem per procedure. Exposure to the thyroid and eye were 2.19 ± 2.07 mrem and 2.64 ± 2.76 mrem, respectively. With the exception of the gluteal region, dosimeter readings from all unprotected areas were significantly higher than those from the chest dosimeter (P < 0.0125). In the course of 13 procedures, 190 mrem of exposure to the hand was recorded by the ring dosimeters. More than 2700 LLIF procedures may be performed annually before occupational limits are exceeded. Conclusion. Prolonged exposure to “low-level” radiation as an occupational risk remains a concern for medical personnel. Radiation exposures to unprotected, radiosensitive locations, such as the axilla or eye, are worrisome. However, following radiation safety guidelines, 2700 LLIF procedures can be performed per year before exceeding occupational dose limits. Adherence to radiation safety guidelines is necessary to avoid sequelae related to an invisible but potentially deadly risk of minimally invasive spine surgery procedures.

Coded excitation ultrasound investigations have the potential to augment the resolution, increase the efficiency, and expand the possibilities of noninvasive diagnostic imaging. B-Flow ultrasound, a type of digitally encoded imaging, was developed more than 20 years ago with the aim to optimize the visualization of blood flow. It has been investigated for a plethora of applications so far. A scoping review regarding its clinical applications was conducted based on a systematic literature research. B-Flow has been investigated in various anatomic locations and pathologies. However, previous research is limited by small sample sizes, the rare occurrence of elaborate study designs, the reliance on subjective reports and qualitative data, as well as several potential biases. While results are in general promising, it should therefore still be considered an emerging technology. Nevertheless, the limitations can be addressed in future research and the potential to expand its applications make B-Flow an interesting candidate for further investigations.