Richard Nasca, Mark Myers and Lisa Ferrara
Luis Marchi, Nitamar Abdala, Leonardo Oliveira, Rodrigo Amaral, Etevaldo Coutinho and Luiz Pimenta
Indirect decompression of the neural structures through interbody distraction and fusion in the lumbar spine is feasible, but cage subsidence may limit maintenance of the initial decompression. The influence of interbody cage size on subsidence and symptoms in minimally invasive lateral interbody fusion is heretofore unreported. The authors report the rate of cage subsidence after lateral interbody fusion, examine the clinical effects, and present a subsidence classification scale.
The study was performed as an institutional review board–approved prospective, nonrandomized, comparative, single-center radiographic and clinical evaluation. Stand-alone short-segment (1- or 2-level) lateral lumbar interbody fusion was investigated with 12 months of postoperative follow-up. Two groups were compared. Forty-six patients underwent treatment at 61 lumbar levels with standard interbody cages (18 mm anterior/posterior dimension), and 28 patients underwent treatment at 37 lumbar levels with wide cages (22 mm). Standing lateral radiographs were used to measure segmental lumbar lordosis, disc height, and rate of subsidence. Subsidence was classified using the following scale: Grade 0, 0%–24% loss of postoperative disc height; Grade I, 25%–49%; Grade II, 50%–74%; and Grade III, 75%–100%. Fusion status was assessed on CT scanning, and pain and disability were assessed using the visual analog scale and Oswestry Disability Index. Complications and reoperations were recorded.
Pain and disability improved similarly in both groups. While significant gains in segmental lumbar lordosis and disc height were observed overall, the standard group experienced less improvement due to the higher rate of interbody graft subsidence. A difference in the rate of subsidence between the groups was evident at 6 weeks (p = 0.027), 3 months (p = 0.042), and 12 months (p = 0.047). At 12 months, 70% in the standard group and 89% in the wide group had Grade 0 or I subsidence, and 30% in the standard group and 11% in wide group had Grade II or III subsidence. Subsidence was detected early (6 weeks), at which point it was correlated with transient clinical worsening, although progression of subsidence was not observed after the 6-week time point. Moreover, subsidence occurred predominantly (68%) in the inferior endplate. Fusion rate was not affected by cage dimension (p > 0.999) or by incidence of subsidence (p = 0.383).
Wider cages avoid subsidence and better restore segmental lordosis in stand-alone lateral interbody fusion. Cage subsidence is identified early in follow-up and can be accessed using the proposed classification scale.
Oheneba Boachie-Adjei, Neel Anand, Gary Fleischer, Khaled Kabaish, Miguel Melgar, Richard Nasca and Thomas Raley
Robert F. Heary
Luis Marchi, Leonardo Oliveira, Etevaldo Coutinho and Luiz Pimenta
Axial lumbar interbody fusion (AxiaLIF) is a minimally invasive presacral surgical technique that damages neither the anulus fibrosus nor the anterior or posterior longitudinal ligaments. The technique was initially designed and used for L5–S1 interbody fusions and recently was extended to 2-level fusions (L4–5 and L5–S1). Until now, only biomechanical and radiological studies have discussed the feasibility of this new indication, and no clinical study has been published. The purpose of this article is to report results and complications associated with 2-level presacral AxiaLIF with a minimum of 24 months of follow-up.
In this prospective, nonrandomized, single-center study, 27 patients underwent presacral AxiaLIF surgery at the L4–5 and L5–S1 levels. Clinical outcomes were assessed using the visual analog scale for back and leg symptoms and the Oswestry Disability Index. Radiographic parameters, such as disc height, segmental lordosis, and bone fusion, were analyzed using radiographs and CT scans. Complications and revision surgeries were recorded as needed. The minimum follow-up was 24 months (up to 72 months).
There were no intraoperative complications. One major complication was observed: a patient developed septicemia that resolved after proper care. Clinical outcomes scores showed overall improvement in pain and physical function. During follow-up, the following complications were observed in the construct: screw breakage (14.8%), proximal/distal transsacral rod detachment (11.1%), radiolucency around the transsacral rod (52%), and cephalic rod migration (24%). Disc height gain was reported early after surgery, but at the 24-month follow-up the disc space was diminished in comparison with the preoperative status. Compared with preoperative values, the 24-month results showed loss of segmental lordosis. Only 22% of all treated levels were considered to have solid fusion at the 24-month radiological evaluation.
Patients undergoing presacral 2-level AxiaLIF experienced satisfactory short-term clinical outcomes; however, complications were commonly seen on imaging studies obtained 24 months postoperatively. Additional studies are required to better understand the 2-level indications for this technique.
Juan S. Uribe, William D. Smith, Luiz Pimenta, Roger Härtl, Elias Dakwar, Urvij M. Modhia, Glen A. Pollock, Vamsi Nagineni, Ryan Smith, Ginger Christian, Leonardo Oliveira, Luis Marchi and Vedat Deviren
Symptomatic herniated thoracic discs remain a surgical challenge and historically have been associated with significant complications. While neurological outcomes have improved with the abandonment of decompressive laminectomy, the attempt to minimize surgical complications and associated morbidities continues through less invasive approaches. Many of these techniques, such as thoracoscopy, have not been widely adopted due to technical difficulties. The current study was performed to examine the safety and early results of a minimally invasive lateral approach for symptomatic thoracic herniated intervertebral discs.
Sixty patients from 5 institutions were treated using a mini-open lateral approach for 75 symptomatic thoracic herniated discs with or without calcification. The mean age was 57.9 years (range 23–80 years), and 53.3% of the patients were male. Treatment levels ranged from T4–5 to T11–12, with 1–3 levels being treated (mean 1.3 levels). The most common levels treated were T11–12 (14 cases [18.7%]), T7–8 (12 cases [16%]), and T8–9 (12 cases [16%]). Symptoms included myelopathy in 70% of cases, radiculopathy in 51.7%, axial back pain in 76.7%, and bladder and/or bowel dysfunction in 26.7%. Instrumentation included an interbody spacer in all but 6 cases (10%). Supplemental internal fixation included anterolateral plating in 33.3% of cases and pedicle screws in 10%; there was no supplemental internal fixation in 56.7% of cases. Follow-up ranged from 0.5 to 24 months (mean 11.0 months).
The median operating time, estimated blood loss, and length of stay were 182 minutes, 290 ml, and 5.0 days, respectively. Four major complications occurred (6.7%): pneumonia in 1 patient (1.7%); extrapleural free air in 1 patient (1.7%), treated with chest tube placement; new lower-extremity weakness in 1 patient (1.7%); and wound infection in posterior instrumentation in 1 patient (1.7%). Reoperations occurred in 3 cases (5%): one for posterior reexploration, one for infection in posterior instrumentation, and one for removal of symptomatic residual disc material. Back pain, measured using the visual analog scale, improved 60% from the preoperative score to the last follow-up, that is, from 7.8 to 3.1. Excellent or good overall outcomes were achieved in 80% of the patients, a fair or unchanged outcome resulted in 15%, and a poor outcome occurred in 5%. Moreover, myelopathy, radiculopathy, axial back pain, and bladder and/or bowel dysfunction improved in 83.3%, 87.0%, 91.1%, and 87.5% of cases, respectively.
The authors' early experience with a large multicenter series suggested that the minimally invasive lateral approach is a safe, reproducible, and efficacious procedure for achieving adequate decompression in thoracic disc herniations in a less invasive manner than conventional surgical techniques and without the use of endoscopes. Symptom resolution was achieved at similar rates using this approach as compared with the most efficacious techniques in the literature, and with fewer complications in most circumstances.
Luiz Pimenta, Leonardo Oliveira, Thomas Schaffa, Etevaldo Coutinho and Luis Marchi
Current lumbar total disc replacement (TDR) devices require an anterior approach for implantation. This approach has inherent limitations, including risks to abdominal structures and the need for resection of the anterior longitudinal ligament (ALL). Placement of a TDR device from a true lateral (extreme lateral interbody fusion [XLIF]) approach is thought to offer a less invasive option to access the disc space, preserving the stabilizing ligaments and avoiding scarring of anterior vasculature. In this study, the authors attempted to quantify the clinical and radiographic outcomes of a lateral approach to lumbar TDR from a prospective, single-center experience.
A TDR device designed for implantation through a true lateral, retroperitoneal, transpsoas approach (XLIF) was implanted in 36 patients with discography-confirmed 1- or 2-level degenerative disc disease. Clinical (pain and function) and radiographic (range of motion [ROM]) data were prospectively collected preoperatively, postoperatively, and serially for a minimum of 24 months' follow-up.
Thirty-six surgeries were performed in 16 men and 20 women (mean age 42.6 years). Surgeries included 15 single-level TDR procedures at L3–4 or L4–5, three 2-level TDR procedures spanning L3–4 and L4–5, and 18 hybrid procedures (anterior lumbar interbody fusion [ALIF]) at L5–S1 and TDR at L4–5  or L3–4 ).
Operative time averaged 130 minutes, with an average blood loss of 60 ml and no intraoperative complications. Postoperative radiographs showed good device placement. All patients were walking within 12 hours of surgery and all but 9 were discharged the next day (7 of 9 had hybrid TDR/ALIF procedures).
Five patients (13.8%) had psoas weakness and 3 (8.3%) had anterior thigh numbness postoperatively, both resolving within 2 weeks. One patient (2.8%) demonstrated weakness of the leg ipsilateral to the approach side, which lasted through the 3-month visit but was resolved by the 6-month visit. One patient (2.8%) was found to have hypertrophy of the quadriceps contralateral to the approach side at the 12-month visit, which was resolved by the 2-year visit. Four patients (11%) had postoperative facet joint pain, all in hybrid cases.
All patients were 2 years or more postsurgery as of this writing, although 3 were lost to follow-up between the 1- and 2-year visits. In 2 cases (5.6%), removal of the TDR device and revision to fusion were required due to unresolved pain. At 2 years' follow-up, the average visual analog scale and Oswestry Disability Index scores had improved 69.6% and 61.4%, respectively, and ROM averaged 8.6°, well within physiological norms.
Long-term results of a laterally placed TDR device demonstrate maintenance of pain relief and functional improvement. The benefits of this technique—minimal morbidity, avoiding mobilization of the great vessels, preserving the ALL, biomechanically stable orientation, and broader revision options—suggest a promising new direction for TDR procedures.