Rhiannon M. Parker

Clinical outcome and fusion rates after the first 30 extreme lateral interbody fusions

Introduction. The lateral transpsoas approach for lumbar interbody fusion (XLIF) is gaining popularity. Studies examining a surgeons early experience are rare. We aim to report treatment, complication, clinical, and radiographic outcomes in an early series of patients. Methods. Prospective data from the first thirty patients treated with XLIF by a single surgeon was reviewed. Outcome measures included pain, disability, and quality of life assessment. Radiographic assessment of fusion was performed by computed tomography. Results. Average follow-up was 11.5 months, operative time was 60 minutes per level and blood loss was 50 mL. Complications were observed: clinical subsidence, cage breakage upon insertion, new postoperative motor deficit and bowel injury. Approach side-effects were radiographic subsidence and anterior thigh sensory changes. Two patients required reoperation; microforaminotomy and pedicle screw fixation respectively. VAS back and leg pain decreased 63% and 56%, respectively. ODI improved 41.2% with 51.3% and 8.1% improvements in PCS and MCS. Complete fusion (last follow-up) was observed in 85%. Conclusion. The XLIF approach provides superior treatment, clinical outcomes and fusion rates compared to conventional surgical approaches with lowered complication rates. Mentor supervision for early cases and strict adherence to the surgical technique including neuromonitoring is essential.

Maintenance of segmental lordosis and disk height in stand-alone and instrumented extreme lateral interbody fusion (XLIF).

Study Design: A prospective single-surgeon nonrandomized clinical study. Objective: To evaluate the radiographic and clinical outcomes, by fixation type, in extreme lateral interbody fusion (XLIF) patients and provide an algorithm for determining patients suitable for stand-alone XLIF. Summary of Background Data: XLIF may be supplemented with pedicle screw fixation, however, since stabilizing structures remain intact, it is suggested that stand-alone XLIF can be used for certain indications. This eliminates the associated morbidity, though subsidence rates may be elevated, potentially minimizing the clinical benefits. Materials and Methods: A fixation algorithm was developed after evaluation of patient outcomes from the surgeon’s first 30 cases. This algorithm was used prospectively for 40 subsequent patients to determine the requirement for supplemental fixation. Preoperative, postoperative, and 12-month follow-up computed tomography scans were measured for segmental and global lumbar lordosis and posterior disk height. Clinical outcome measures included back and leg pain (visual analogue scale), Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS). Results: Preoperatively to 12-month follow-up there were increases in segmental lordosis (7.9–9.4 degrees, P=0.0497), lumbar lordosis (48.8–55.2 degrees, P=0.0328), and disk height (3.7–5.5 mm, P=0.0018); there were also improvements in back (58.6%) and leg pain (60.0%), ODI (44.4%), PCS (56.7%), and MCS (16.1%) for stand-alone XLIF. For instrumented XLIF, segmental lordosis (7.6–10.5 degrees, P=0.0120) and disk height (3.5–5.6 mm, P<0.001) increased, while lumbar lordosis decreased (51.1–45.8 degrees, P=0.2560). Back (49.8%) and leg pain (30.8%), ODI (32.3%), PCS (37.4%), and MCS (2.0%) were all improved. Subsidence occurred in 3 (7.5%) stand-alone patients. Conclusions: The XLIF treatment fixation algorithm provided a clinical pathway to select suitable patients for stand-alone XLIF. These patients achieved positive clinical outcomes, satisfactory fusion rates, with sustained correction of lordosis and restoration of disk height.

Anterior lumbar interbody fusion using recombinant human bone morphogenetic protein–2: a prospective study of complications

OBJECT The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in anterior lumbar interbody fusion (ALIF) is controversial regarding the reported complication rates and cost. The authors aimed to assess the complication rates of performing ALIF using rhBMP-2. METHODS This is a prospective study of consecutive patients who underwent ALIF performed by a single spine surgeon and a single vascular surgeon between 2009 and 2012. All patients underwent placement of a polyetheretherketone (PEEK) cage filled with rhBMP-2 and a separate anterior titanium plate. Preoperative clinical data, operative details, postoperative complications, and clinical and radiographic outcomes were recorded for all patients. Clinical outcome measures included back and leg pain visual analog scale scores, Oswestry Disability Index (ODI), and SF-36 Physical and Mental Component Summary (PCS and MCS) scores. Radiographic assessment of fusion was performed using high-definition CT scanning. Male patients were screened pre- and postoperatively regarding sexual dysfunction, specifically retrograde ejaculation (RE). RESULTS The study comprised 131 patients with a mean age of 45.3 years. There were 67 men (51.1%) and 64 women (48.9%). Of the 131 patients, 117 (89.3%) underwent ALIF at L5-S1, 9 (6.9%) at L4-5, and 5 (3.8%) at both L4-5 and L5-S1. The overall complication rate was 19.1% (25 of 131), with 17 patients (13.0%) experiencing minor complications and 8 (6.1%) experiencing major complications. The mean estimated blood loss per ALIF level was 115 ml. There was 1 incidence (1.5%) of RE. No significant vascular injuries occurred. No prosthesis failure occurred with the PEEK cage and separate anterior screw-plate. Back and leg pain improved 57.2% and 61.8%, respectively. The ODI improved 54.3%, with PCS and MCS scores improving 41.7% and 21.3%, respectively. Solid interbody fusion was observed in 96.9% of patients at 12 months. CONCLUSIONS Anterior lumbar interbody fusion with a vascular access surgeon and spine surgeon, using a separate cage and anterior screw-plate, provides a very robust and reliable construct with low complication rates, high fusion rates, and positive clinical outcomes, and it is cost-effective. The authors did not experience the high rates of RE reported by other authors using rhBMP-2.

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

OBJECT Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF. METHODS A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores. RESULTS Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049). CONCLUSIONS The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

Clinical results and limitations of indirect decompression in spinal stenosis with laterally implanted interbody cages: results from a prospective cohort study

PurposeThe lateral approach for anterior interbody fusion allows placement of a large footprint intervertebral spacer to indirectly decompress the neural elements through disc height restoration and resultant soft tissue changes. However, it is not well understood under what circumstances indirect decompression in lateral approach surgery is sufficient. This report aimed to evaluate clinical scenarios where indirect decompression was and was not sufficient in symptom resolution when using lateral interbody fusion.MethodsA prospective study was undertaken of 122 consecutive patients treated with lateral interbody fusion without direct decompression. Pre- and postoperative symptomatology was assessed to evaluate the extent of neural decompression following implantation with a lateral polyetheretherketone spacer. Failure to improve or resolve preoperative radicular pain was considered a failure of indirect decompression and indicated these patients for additional posterior decompressive surgery.ResultsUnplanned second stage decompression was required in 11 patients. Of these patients, 7/11 early in this series had pathology that was underappreciated including spondylolisthesis from high grade facet arthropathy with instability (3), bony lateral recess stenosis (3) and both spondylolisthesis/stenosis (1). Three patients had iatrogenic leg pain through cage misplacement. There was one failure of indirect decompression that could not be explained through retrospective analysis of the patient’s record.ConclusionIndirect decompression clearly has a role in minimizing the amount of surgery that is required. However, it is important to consider the circumstances where this technique may be effective and preoperative considerations that may improve patient selection.

Indirect foraminal decompression is independent of metabolically active facet arthropathy in extreme lateral interbody fusion.

Study Design. Retrospective analysis of prospectively collected, nonrandomized radiographical data. Objective. To examine the relationship between the presence of preoperative metabolically active facet arthropathy (FA) and the amount of indirect foraminal decompression gained after extreme lateral interbody fusion (XLIF). Summary of Background Data. Although evidence of significant radiographical indirect decompression after XLIF has been shown, the relationship between the extent of indirect decompression and the presence of potentially attenuating, FA is yet to be studied. Methods. A prospective database of consecutive patients undergoing XLIF was retrospectively analyzed. Posterior disc height, foraminal height, and cross-sectional foraminal area were measured on computed tomographic scans obtained preoperatively and 2 days postoperatively. The selected radiographical parameters were examined with respect to the presence of FA based on preoperative computed tomographic and bone scans. Results. Fifty-two consecutive patients underwent 79 levels of XLIF without direct decompression. Average age was 66.4 years and 34 (65.4%) were females. Surgery resulted in significant increases in posterior disc height 3.0 to 5.7 mm (89.0% increase), P < 0.0001; foraminal height 1.4 to 1.7 cm (38.0% increase), P < 0.0001; and foraminal area 1.1 to 1.4 cm2 (45.1% increase), P < 0.0001. These increases were independent of the presence of metabolically active arthropathy. Conclusion. Significant indirect neural decompression is possible in XLIF, regardless of the presence of metabolically active FA. Level of Evidence: 3

Cervical artificial disc replacement with ProDisc-C: Clinical and radiographic outcomes with long-term follow-up

Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion. We evaluated the clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up. Data were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up.

Bone Scans Are Reliable for the Identification of Lumbar Disk and Facet Pathology

Study Design Surgeon survey. Objective To evaluate the reliability of bone single-photon emission computed tomography (SPECT) versus bone SPECT images co-registered with computed tomography (bone SPECT-CT) by analyzing interobserver agreement for identification of the anatomical location of technetium99m-labeled oxidronate uptake in the lumbar disk and/or facet joint. Methods Seven spine surgeons interpreted 20 bone scans: 10 conventional black-and-white tomograms (bone SPECT) and 10 color-graded bone SPECT-CT scans. Each surgeon was asked to identify the location of any diagnostically relevant uptake in the disk and/or facet joint between L1 and S1. Reliability was evaluated using the free-marginal kappa statistic, and the level of agreement was assessed using the Landis and Koch interpretation. Results Conventional bone SPECT scans and bone SPECT-CT scans were reliable for the identification of diagnostically relevant uptake, with bone SPECT-CT having higher reliability (kappa = 0.72) than bone SPECT alone (0.59). Bone SPECT and bone SPECT-CT were also reliable in identifying disk pathology, with kappa values of 0.72 and 0.81, respectively. However, bone SPECT-CT was more reliable (0.81) than bone SPECT (0.60) when identifying facet disease. Conclusions For the identification of disk pathology, it is reasonable to use either conventional bone SPECT or bone SPECT-CT; however, bone SPECT-CT is more reliable for facet joint pathology.

Choice of Approach Does Not Affect Clinical and Radiologic Outcomes: A Comparative Cohort of Patients Having Anterior Lumbar Interbody Fusion and Patients Having Lateral Lumbar Interbody Fusion at 24 Months.

Study Design Retrospective analysis of prospectively collected registry data. Objective This study aimed to compare the clinical and radiologic outcomes between comparative cohorts of patients having anterior lumbar interbody fusion (ALIF) and patients having lateral lumbar interbody fusion (LLIF). Methods Ninety consecutive patients were treated by a single surgeon with either ALIF (n = 50) or LLIF (n = 40). Inclusion criteria were patients age 45 to 70 years with degenerative disk disease or grade 1 to 2 spondylolisthesis and single-level pathology from L1 to S1. Patient-reported outcome measures included pain (visual analog scale), disability (Oswestry Disability Index [ODI]), and quality of life (Short Form 36 physical component score [PCS] and mental component scores [MCS]). Assessment of fusion and measurement of lordosis and posterior disk height were performed on computed tomography scans. Results At 24 months, patients having ALIF had significant improvements in back (64%) and leg (65%) pain and ODI (60%), PCS (44%), and MCS (26%; p < 0.05) scores. Patients having LLIF had significant improvements in back (56%) and leg (57%) pain and ODI (52%), PCS (48%), and MCS (12%; p < 0.05) scores. Fourteen complications occurred in the ALIF group, and in the LLIF group, there were 17 complications (p > 0.05). The fusion rate was 100% for ALIF and 95% for LLIF (p = 0.1948). ALIF added ∼6 degrees of lordosis and 3 mm of height, primarily measured at L5–S1, and LLIF added ∼3 degrees of lordosis and 2 mm of height between L1 to L5. Mean follow-up was 34.1 months. Conclusions In comparative cohorts of patients having ALIF and patients having LLIF at 24 months postoperatively, there were no significant differences in clinical outcomes, complication rates, or fusion rates.

Brief intraoperative heparinization and blood loss in anterior lumbar spine surgery.

OBJECT The anterior approach to the lumbar spine may be associated with iliac artery thrombosis. Intraoperative heparin can be administered to prevent thrombosis; however, there is a concern that this will increase the procedural blood loss. The aim of this study was to examine whether intraoperative heparin can be administered without increasing blood loss in anterior lumbar spine surgery. METHODS A prospective study of consecutive anterior approaches for lumbar spine surgery was performed between January 2009 and June 2014 by a single vascular surgeon and a single spine surgeon. Patients underwent an anterior lumbar interbody fusion (ALIF) at L4-5 and/or L5-S1, a total disc replacement (TDR) at L4-5 and/or L5-S1, or a hybrid procedure with a TDR at L4-5 and an ALIF at L5-S1. Heparin was administered intravenously when arterial flow to the lower limbs was interrupted during the procedure. Heparin was usually reversed on removal of the causative retraction. RESULTS The cohort consisted of 188 patients with a mean age of 41.7 years; 96 (51.1%) were male. Eighty-four patients (44.7%) had an ALIF, 57 (30.3%) had a TDR, and 47 (25.0%) had a hybrid operation with a TDR at L4-5 and an ALIF at L5-S1. One hundred thirty-four patients (71.3%) underwent a single-level procedure (26.9% L4-5 and 73.1% L5-S1) and 54 (28.7%) underwent a 2-level procedure (L4-5 and L5-S1). Seventy-two patients (38.3%) received heparinization intraoperatively. Heparin was predominantly administered during hybrid operations (68.1%), 2-level procedures (70.4%), and procedures involving the L4-5 level (80.6%). There were no intraoperative ischemic vascular complications reported in this series. There was 1 postoperative deep venous thrombosis. The overall mean estimated blood loss (EBL) for the heparin group (389.7 ml) was significantly higher than for the nonheparin group (160.5 ml) (p < 0.0001). However, when all variables were analyzed with multiple linear regression, only the prosthesis used and level treated were found to be significant in blood loss (p < 0.05). The highest blood loss occurred in hybrid procedures (448.1 ml), followed by TDR (302.5 ml) and ALIF (99.7 ml). There were statistically significant differences between the EBL during ALIF compared with TDR and hybrid (p < 0.0001), but not between TDR and hybrid. The L4-5 level was associated with significantly higher blood loss (384.9 ml) compared with L5-S1 (111.4 ml) (p < 0.0001). CONCLUSIONS During an anterior exposure for lumbar spine surgery, the administration of heparin does not significantly increase blood loss. The prosthesis used and level treated were found to significantly increase blood loss, with TDR and the L4-5 level having greater blood loss compared with ALIF and L5-S1, respectively. Heparin can be administered safely to help prevent thrombotic intraoperative vascular complications without increasing blood loss.