OLLIF and Obesity: Breaking the Vicious Cycle

Introduction

Obesity is a major public health concern globally, leading the World Health Organization to declare it a worldwide epidemic in 1997. Today, 37.7% of Americans are obese and 7.7% are morbidly obese. Obesity increases one’s risk for a wide variety of health conditions including lower back pain. As almost 80% of all people will suffer from this condition at some point during their lives, chronic back pain is one of the most prevalent and expensive health conditions in the Western world. The critical dilemma created by obesity, back pain and spine disease is that each of these conditions negatively reinforces the others. Simply stated, spine pain severely limits one’s ability to move making it extremely difficult to lose weight due to this lack of physical activity, hence, a vicious cycle or “catch-22” is created, which is extremely hard to break.

Not all spinal pain must be treated via fusion or other surgical techniques. In fact, most back and corresponding leg pain is effectively treated with conservative measures, providing the basis for Inspired Spine’s comprehensive protocols which are exhausted long before surgery is even considered for a patient. However, for those patients whose pain is not relieved via the employment of these conservative measures, lumbar fusion has been demonstrated and documented to be an effective surgical treatment.

Traditional lumbar fusion procedures performed on obese patients are typically longer and exponentially more challenging surgeries with increased complication rates, such as infections. As a result, these procedures require longer post-operative hospital stays and are more expensive. Spine surgery performed on obese patients is generally considered more technically challenging than procedures performed on non-obese patients due to the substantially greater amount of the tissue that must be traversed to access the area being treated. Many surgeons do not offer surgical treatment to higher BMI (Body Mass Index) patients due to their justifiable concerns about these technical challenges.

BMI 45

BMI 30

In BMI below 30 only half of the instrument is under the skin

There exists an increasing amount of evidence from all areas of medicine (OBGYN, Urology, general surgery and orthopedics) that minimally invasive surgery is tremendously beneficial to the patient. Although there has been an increase in the number of minimally invasive spine surgery (MISS) procedures performed, MISS has not broadly infiltrated into general spine surgery practices. This lack of adoption is primarily due to the fact that early MISS techniques, such as MIS-TLIF, increase surgery time relative to traditional open procedures. The primary reason for the increased surgery duration required for the MIS-TLIF is that this technique is simply an open procedure (“mini-open”) performed through a smaller access portal as it still requires direct visualization. Therefore, mini-open procedures are generally considered more difficult to perform on obese patients. However, the OLLIF (Oblique Lateral Lumbar Interbody Fusion) requires one-third to one-half the surgical time versus that required for a traditional open fusion. Substantial evidence indicates that increasing surgery time, which requires increased anesthesia usage, strongly correlates to increased surgery related complications and adversely impacts surgical outcomes.

We have studied the impact of obesity on perioperative outcomes in patients who underwent Transforaminal Lumbar Interbody Fusion (TLIF), Minimally Invasive-TLIF (MIS-TLIF), and Oblique Lateral Lumbar Interbody Fusion (OLLIF).

Not only has OLLIF been demonstrated to drastically decrease surgical time, it can be performed with the same procedure efficiency and deliver the same patient outcome benefits in high BMI patients as it does for patients possessing normal BMIs. As evidenced by the literature published to date, no other spinal fusion procedure can be performed with such a track record for high BMI patients. The graph below illustrates the impact of obesity (BMI) on surgical time for a series of OLLIF cases and TLIF cases performed during the same time period. As demonstrated by the data, TLIF becomes exponentially more difficult for high BMI patients, whereas patient BMI has no impact on the OLLIF’s efficiency (required procedure duration) and safety (blood loss).

Results

Summary statistics for the two study groups are displayed in the graphs above. OLLIF is significantly faster than TLIF for all levels and all patients. For a single level procedure, OLLIF reduces the TOTAL surgery time by half, from 3 hours to 1.5 hours. This duration includes the total time that the patient is in the OR including the perioperative anesthesia induction time (identical duration for both TLIF and OLLIF). By subtracting the perioperative anesthesia induction time to calculate the actual surgery time (“skin to skin” duration), the results delivered by the OLLIF are even more impressive versus the TLIF. Also, Blood Loss for the OLLIF procedures is substantially and consistently lower than that associated with the TLIF procedures.

Effect of Obesity

To determine whether high BMI increases surgery time, we performed linear regressions with surgery time as the dependent variable and BMI as the independent variable for each combination of procedure type and number of levels fused. Increased BMI significantly increases surgery time for 1 and 2 level TLIFs but not for OLLIFs.

OLLIF fusions reduce blood loss because they require smaller incisions, decrease dissections of muscles and soft tissue, and avoid epidural bleeding. In addition, OLLIF does not require bone removal to enable cage placement, which further limits blood loss. Unlike other MISS fusions, OLLIF decreases surgery time relative to open techniques. This finding is consistent with the results from our previous studies. The consistent decrease in operative duration is an important result given that a clear direct correlation has been established between surgery time and surgery/anesthesia related complications.

For the TLIF approach, surgery times increase significantly with BMI, which is consistent with other studies. Alternatively, BMI has no effect on surgery time for the OLLIF approach. To perform a TLIF procedure, the spine must be exposed and directly visualized. In obese patients, more time must be spent dissecting tissue during the approach and closure may also require more time. For the OLLIF procedure, however, no dissection of soft tissues is required. The probe that is employed to secure access to the disc space can be advanced quickly through the subcutaneous layers of fat, muscle and fascia. Obesity does not impact the difficulty of the OLLIF procedure, making it the ultimate option for treating this population. The approach may even be easier because the perineural fat creates a cushion around the nerve root, improving OLLIF’s safety profile in moderately obese patients.

Other MISS fusions approach the spine anteriorly. Anterior approaches have been demonstrated to improve patient outcomes relative to posterior approaches. Unfortunately, access to the lumbar spine from an anterior angle is difficult because the surgeon must traverse abdominal or retroperitoneal structures, which often requires an access surgeon. In morbidly obese patients, these approaches may be extremely difficult and dangerous. OLLIF combines the advantages of anterior fusions with a simple approach that is not significantly affected by obesity.

Due to the reduced surgery time and hospital stay, OLLIF reduces perioperative cost relative to open procedures . Previous studies have demonstrated that the perioperative costs of spinal fusions are increased for obese patients. In this study, we have shown that for the OLLIF approach, obesity does not significantly affect surgery time. Therefore, OLLIF may lower the costs associated with performing lumbar fusions on obese patients.