Biologics and Minimally Invasive Approach to TLIFs: What Is the Risk of Radiculitis?

BACKGROUND: Bone morphogenetic protein (BMP) and allograft containing mesenchymal stem cells (live cell) are popular biologic substitutes for iliac crest autograft used in transforaminal lumbar interbody fusion (TLIF). Use of these agents in the pathogenesis of postoperative radiculitis remains controversial. Recent studies have independently linked minimally invasive (MIS) TLIF with increased radiculitis risk compared to open TLIF. The purpose of this study was to assess the rate of postoperative radiculitis in open and MIS TLIF patients along with its relationship to concurrent biologic adjuvant use. METHODS: Patients ≥18 years undergoing single-level TLIF from June 2012 to December 2018 with minimum 1-year follow-up were included. Outcome measures were rate of radiculitis, intra- and postoperative complications, revision surgery; length of stay (LOS), and estimated blood loss (EBL). RESULTS: There were 397 patients: 223 with open TLIFs, 174 with MIS TLIFs. One hundred and fifty-nine surgeries used bone morphogenetic protein (BMP), 26 live cell, 212 neither. Open TLIF: higher mean EBL, LOS, and Charlson Comorbidity Index (CCI) than MIS. Postoperative radiculitis in 37 patients (9.32% overall): 16 cases MIS BMP (15.69% of their cohort), 6 MIS without BMP (8.33%), 5 open BMP (8.77%), 10 open without BMP (6.02%). MIS TLIF versus open TLIF: no differences in 1-year reoperation rates, infection/wound complication, pseudarthrosis, or postoperative complication rate. BMP versus non-BMP: no differences in reoperation rates, infection/wound complication, pseudarthrosis, or postoperative complication rate. Multivariate logistic regression found that neither BMP (P = .109) nor MIS (P = .314) was an independent predictor for postoperative radiculitis when controlled for age, gender, body mass index, and CCI. Using paired open and MIS groups (N = 168 each) with propensity score matching, these variables were still not independently associated with radiculitis (P = .174 BMP, P = .398 MIS). However, the combination of MIS with BMP was associated with increased radiculitis risk in both the entire patient cohort (odds ratio [OR]: 2.259 [1.117-4.569], P = .023, N = 397) and PSM cohorts (OR: 2.196 [1.045-4.616], P = .038, N = 336) compared to other combinations of surgical approach and biologic use. CONCLUSION: Neither the MIS approach nor BMP use is an independent risk factor for post-TLIF radiculitis. However, risk of radiculitis significantly increases when they are used in tandem. This should be considered when selecting biological adjuvants for MIS TLIF. LEVEL OF EVIDENCE: 3.

Importance of the Sagittal Plane in Understanding Adult Spinal Deformities.

The sagittal plane is known to be important in correction of adult spinal deformity. When surgery is indicated, the surgeon is provided with several tools and techniques to restore balance. But proper use of these tools is essential to avoid harmful complications. This article examines these tools with a focus on lumbar lordosis and the lumbopelvic junction. Positioning, releases, osteotomies, and instrumentation are considered with special attention to the alignment measurements they affect.

The role of the progressive ankylosis protein (ANK) in adipogenic/osteogenic fate decision of precursor cells.

The progressive ankylosis protein (ANK) is a transmembrane protein that transports intracellular pyrophosphate (PPi) to the extracellular milieu. In this study we show increased fatty degeneration of the bone marrow of adult ank/ank mice, which lack a functional ANK protein. In addition, isolated bone marrow stromal cells (BMSCs) isolated from ank/ank mice showed a decreased proliferation rate and osteogenic differentiation potential, and an increased adipogenic differentiation potential compared to BMSCs isolated from wild type (WT) littermates. Wnt signaling pathway PCR array analysis revealed that Wnt ligands, Wnt receptors and Wnt signaling proteins that stimulate osteoblast differentiation were expressed at markedly lower levels in ank/ank BMSCs than in WT BMSCs. Lack of ANK function also resulted in impaired bone fracture healing, as indicated by a smaller callus formed and delayed bone formation in the callus site. Whereas 5weeks after fracture, the fractured bone in WT mice was further remodeled and restored to original shape, the fractured bone in ank/ank mice was not fully restored and remodeled to original shape. In conclusion, our study provides evidence that ANK plays a critical role in the adipogenic/osteogenic fate decision of adult mesenchymal precursor cells. ANK functions in precursor cells are required for osteogenic differentiation of these cells during adult bone homeostasis and repair, whereas lack of ANK functions favors adipogenic differentiation.

Distal femoral varus osteotomy for unloading valgus knee malalignment: a biomechanical analysis.

PURPOSE: To investigate the biomechanical properties of the load shifting following opening-wedge distal femoral varus osteotomies (DFVOs) and determine the osteotomy correction needed to unload the lateral compartment. METHODS: Five human cadaveric knees were tested with a load of 500 N of axial compression. Medial and lateral tibiofemoral compartment contact area and pressure were assessed utilizing a modified F-scan pressure-sensitive sensor. The knees were tested in their baseline anatomic alignment, 10° valgus malalignment and following corrective DFVOs of 5°, 10° and 15°. The load shifting effect of the various DFVO correction angles was analysed using a one-way ANOVA to determine the correction angle necessary to unload the lateral compartment. RESULTS: Gradually shifting the loading vector medially with increasing DFVO angles resulted in a decrease in the mean contact area and mean contact pressures in the lateral compartment with progressive increases in the medial compartment. The largest reduction in lateral compartment pressure and contact area was seen with the 15° osteotomy with a 25 % decrease in mean contact pressure and 20 % decrease in mean maximum contact pressure and mean contact area when compared to the 10° valgus-malaligned knee. For the 10° valgus knee, a 15° correction resulted in near-normal contact pressures and areas compared with the knee in normal anatomic alignment. CONCLUSION: Progressive unloading of the lateral tibiofemoral compartment occurred with increasing DFVO correction angles. Clinically, when performing a DFVO for valgus malalignment, surgeons should consider overcorrecting the osteotomy by 5° to restore near-normal contact pressures and contact areas in the lateral compartment rather than the traditional teaching of correcting to neutral alignment.

Current Evidence of Minimally Invasive Spine Surgery in the Treatment of Lumbar Disc Herniations.

With the advent of new instrumentation and better imaging techniques that allowed less tissue trauma compared with traditional open procedures, while providing adequate or enhanced visualization of the pathologic site and based upon the successful experience of outpatient spine surgery to assist early ambulation, the trend and evolution toward ''minimal access'' or minimally invasive spine surgery began to develop with greater intensity. Many surgical techniques have flourished with the promise of delivering a safe and efficient alternative, including chemonucleolysis, manual percutaneous discectomy (MPD), automated percutaneous lumbar discectomy (APLD), and percutaneous lumbar laser discectomy (PLLD). Unfortunately, most of these techniques have been demonstrated to be inefficient with high complication rates. Only modifications of the original open discectomy in which direct visualization of the disc is obtained through either microscopic or endoscopic techniques have proven to be successful. This review outlines the historical journey that has inspired the development of these techniques and delineates the progressive clinical experience gained from their advent.

The effects of Amicar and TXA on lumbar spine fusion in an animal model.

STUDY DESIGN: Animal model. OBJECTIVE: To determine whether aminocaproic acid (Amicar) and tranexamic acid (TXA) inhibit spine fusion volume. SUMMARY OF BACKGROUND DATA: Amicar and TXA are antifibrinolytics used to reduce perioperative bleeding. Prior in vitro data showed that antifibrinolytics reduce osteoblast bone mineralization. This study tested whether antifibrinolytics Amicar and TXA inhibit spine fusion. METHODS: Posterolateral L4-L6 fusion was performed in 50 mice, randomized into groups of 10, which received the following treatment before and after surgery: (1) saline; (2) TXA 100 mg/kg; (3) TXA 1000 mg/kg; (4) Amicar 100 mg/kg; and (5) Amicar 1000 mg/kg. High-resolution plane radiography was performed after 5 weeks and micro-CT (computed tomography) was performed at the end of the 12-week study. Radiographs were graded using the Lenke scale. Micro-CT was used to quantify fusion mass bone volume. One-way analysis of variance by ranks with Kruskal-Wallis testing was used to compare the radiographical scores. One-way analysis of variance with least significant difference post hoc testing was used to compare the micro-CT bone volume. RESULTS: The average±standard deviation bone volume/total volume (%) measured in the saline, TXA 100 mg/kg, TXA 1000 mg/kg, Amicar 100 mg/kg, and Amicar 1000 mg/kg groups were 10.8±2.3%, 9.7±2.2%, 13.4±3.2%, 15.5±5.2%, and 17.9±3.5%, respectively. There was a significant difference in the Amicar 100 mg/kg (P<0.05) and Amicar 1000 mg/kg (P<0.001) groups compared with the saline group. There was greater bone volume in the Amicar groups compared with the TXA group (P<0.001). There was more bone volume in the TXA 1000 mg/kg group compared with TXA 100 mg/kg (P<0.05) but the bone volume in neither of the TXA groups was different to saline (P=0.49). There were no between-group differences observed using plane radiographical scoring. CONCLUSION: Amicar significantly "enhanced" the fusion bone mass in a dose-dependent manner, whereas TXA did not have a significant effect on fusion compared with saline control.These data are in contrast to prior in vitro data that antifibrinolytics inhibit osteoblast bone mineralization. LEVEL OF EVIDENCE: N/A.

Annexin A6 interacts with p65 and stimulates NF-κB activity and catabolic events in articular chondrocytes.

OBJECTIVE: ANXA6, the gene for annexin A6, is highly expressed in osteoarthritic (OA) articular chondrocytes but not in healthy articular chondrocytes. This study was undertaken to determine whether annexin A6 affects catabolic events in these cells. METHODS: Articular chondrocytes were isolated from Anxa6-knockout mice, wild-type (WT) mice, and human articular cartilage in which ANXA6 was overexpressed. Cells were treated with interleukin-1ß (IL-1ß) or tumor necrosis factor α (TNFα), and expression of catabolic genes and activation of NF-κB were determined by real-time polymerase chain reaction and luciferase reporter assay. Anxa6(-/-) and WT mouse knee joints were injected with IL-1ß or the medial collateral ligament was transected and partial resection of the medial meniscus was performed to determine the role of Anxa6 in IL-1ß-mediated cartilage destruction and OA progression. The mechanism by which Anxa6 stimulates NF-κB activity was determined by coimmunoprecipitation and immunoblot analysis of nuclear and cytoplasmic fractions of IL-1ß-treated Anxa6(-/-) and WT mouse chondrocytes for p65 and Anxa6. RESULTS: Loss of Anxa6 resulted in decreased NF-κB activation and catabolic marker messenger RNA (mRNA) levels in IL-1ß- or TNFα-treated articular chondrocytes, whereas overexpression of ANXA6 resulted in increased NF-κB activity and catabolic marker mRNA levels. Annexin A6 interacted with p65, and loss of Anxa6 caused decreased nuclear translocation and retention of the active p50/p65 NF-κB complex. Cartilage destruction in Anxa6(-/-) mouse knee joints after IL-1ß injection or partial medial meniscectomy was reduced as compared to that in WT mouse joints. CONCLUSION: Our data define a role of annexin A6 in the modulation of NF-κB activity and in the stimulation of catabolic events in articular chondrocytes.

Outcomes analysis of anterior-posterior fusion for low grade isthmic spondylolisthesis.

BACKGROUND: Traditional surgical treatment of isthmic spondylolisthesis is posterior-lateral fusion, but the addition of anterior surgery has been explored. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis. METHODS: Retrospectively, we enrolled 23 consecutive patients (mean age of 50) who underwent surgical treatment for low grade isthmic spondylolisthesis. The mean follow-up was 10 months. Basic demographic and radiographic data was collected. Pre- and post-surgical clinical surveys (VAS, ODI, and SF-36) were collected. RESULTS: All 23 patients underwent anterior interbody fusion with a femoral ring allograft or ICBG in combination with posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (p = 0.24) while slip angle increased from 9.8° to 17.9° (p < 0.001) and average disc height decreased from 1.9 cm to 0.80 cm (p < 0.001). VAS scores decreased from 7.1 to 2.4 (p < 0.001), ODI scores decreased from 52.5 to 28.1 (p < 0.001), and SF-36 scores increased in the Physical Component Scale (PCS) from 29.5 to 42.6 (p < 0.001). CONCLUSION: In our study, patients demonstrated an improvement in the ODI as well the physical component scores of the SF-36, thus having a good clinical outcome.

The Incidence of Potential Candidates for Total Disc Replacement among Lumbar and Cervical Fusion Patient Populations.

STUDY DESIGN: Retrospective chart review. PURPOSE: To evaluate the incidence of potential total disc replacement (TDR) candidates among cervical and lumbar fusion patient populations using strict Food and Drug Administration (FDA) criteria and with relative exclusion criteria removed. OVERVIEW OF LITERATURE: Recent studies suggest that the potential percentage of patients that are candidates for TDR ranges from 0-5% in lumbar fusions and 43% in cervical fusions. METHODS: We performed a retrospective chart review of 280 consecutive patients who had lumbar (n = 174) and cervical (n = 106) fusion or TDR performed by one of four independent adult orthopaedic spine surgeons. Charts were screened for investigational device exemption (IDE) inclusion/exclusion criteria and later reanalyzed excluding relative exclusion criteria, such as history of chronic medical illness, twolevel disease (cervical cases), and history of prior fusion surgery in the anatomic region. RESULTS: Of the 174 lumbar surgeries, 10 were TDR with Prodisc-L and 164 were lumbar fusions. The most common TDR exclusion criteria were lytic spondylolisthesis or spinal stenosis (47.7% of patients) and more than 2 level degenerative disc disease (37.9%). 14.9% had no IDE exclusion criteria and would be considered candidates for TDR. After excluding the relative lumbar exclusion criteria, this percentage increased to 25.8%. Of the 106 cervical cases, 3 had a TDR with Prodisc-C and 103 had a cervical fusion. Twenty eight percent had no IDE exclusion criteria and would be considered candidates for cervical TDR. CONCLUSIONS: A larger percentage of cervical fusion candidates are potential candidates for TDR (28%) than lumbar fusion candidates (14.9%) based on the strict IDE criteria.

Cost-effectiveness of a Staphylococcus aureus screening and decolonization program for high-risk orthopedic patients.

We conducted a Markov decision analysis to assess the cost savings associated with a preoperative Staphylococcus aureus screening and decolonization program on 365 hip and knee arthroplasties and 287 spine fusions. A 2-way sensitivity analysis was also used to calculate the needed reduction in surgical site infections to make the program cost saving. If cost of treating an infected hip or knee arthroplasty is equal to the cost of a primary knee arthroplasty, then the screening program needs to result in a 35% reduction in the revision rate, or a relative revision rate of 65% for patients in the screening program, to be cost saving. For spine fusions, the reduction in the revision rate to make the program cost saving is only 10%. Universal Staphylococcus aureus screening and decolonization for hip and knee arthroplasty and spinal fusion patients needs to result in only a modest reduction in the surgical site infection rate to be cost saving.

Rupture of the distal biceps tendon combined with a supinator muscle tear in a 51-year-old woman: a case report.

Distal biceps tendon rupture is a relatively uncommon occurrence in the general female population, and to our knowledge, has not been reported in association with a supinator muscle tear. We report a case of 51-year-old woman who experienced sharp pain in her forearm and elbow after lifting a heavy object. History and physical examination raised suspicion for a distal biceps tendon rupture. MRI imaging determined a combined distal biceps tendon tear with a supinator muscle tear with subsequent confirmation at surgery. Surgical repair was performed for the distal biceps tendon only through a single incision approach using the Endobutton technique.

Intervertebral foramen size and volume changes in low grade, low dysplasia isthmic spondylolisthesis.

STUDY DESIGN: Anatomic study. OBJECTIVE: The purpose of this study is to determine the effect of the slip amount, slip angle, and disc height on the geometry of the L5 foramen in low-grade, low-dysplasia isthmic L5 spondylolisthesis using a human cadaveric model. SUMMARY OF BACKGROUND DATA: Radicular pain and varying degrees of nerve root dysfunction are present in many adult isthmic spondylolisthesis patients and can be the result of compression of the L5 root within its foramen. METHODS: The intervertebral foramens of six L5 vertebra and sacrum cadaver specimens had a standardized pars defect created and were mounted on an adjustable frame. Plasticene molds of the foramens were made by varying sagittal translocation (0%, 12.5%, 25%, and 50%), slip angle (kyphotic 10° and lordotic 0°, 10°, 20°, and 30°), and disc height (0, 5, and 10 mm). The volume of each mold was measured. The surface area was determined by sagittally slicing on a microtome the mold and each section's face was measured by computer image analysis. RESULTS: The area and volume of the foramen at a sagittal slip of 0%, slip angle of 0°, and 0 mm disc height were used as a control. As disc height decreased from 10 to 5 mm, 10 to 0 mm, and 5 to 0 mm, the foramen area and volume significantly decreased (P < 0.05). Incremental slip percentage from 0% to 12.5%, 25%, and 50% produced significantly reduced foramen area and volumes (P < 0.05). As slip angle increased from 10° kyphosis to 0°, 10°, 20°, and 30° lordosis, foramen area and volume decreased (P < 0.05). CONCLUSION: Disc height and slip percentage had the largest effect on intervertebral foramen area and volume in this model of low-grade, low-dysplasia isthmic spondylolisthesis. Slip angle changes affected foramen area to a lesser degree. Surgical treatment strategies should consider restoration of disc height in cases with foraminal stenosis.

Hospital cost analysis of adolescent idiopathic scoliosis correction surgery in 125 consecutive cases.

BACKGROUND: Although achieving clinical success is the main goal in the surgical treatment of adolescent idiopathic scoliosis, it is becoming increasingly important to do so in a cost-effective manner. The goal of the present study was to determine the surgical and hospitalization costs, charges, and reimbursements for adolescent idiopathic scoliosis correction surgery at one institution. METHODS: We performed a retrospective review of 16,536 individual costs and charges, including overall reimbursements, for 125 consecutive patients who were managed surgically for the treatment of adolescent idiopathic scoliosis by three different surgeons between 2006 and 2007. Demographic, surgical, and radiographic data were recorded for each patient. Stepwise multiple linear regression analysis was employed to assess independent correlation with total cost and charge. Nonparametric descriptive statistics were calculated for total cost with use of the Lenke curve-classification system. RESULTS: The mean age of the patients was 15.2 years. The mean main thoracic curve measured 50 degrees, and the thoracolumbar curve measured 41 degrees. The cost varied with Lenke curve type: $29,955 for type 1, $31,414 for type 2, $31,975 for type 3, $60,754 for type 4, $32,652 for type 5, and $33,416 for type 6. Independently significant increases for total cost were found in association with the number of pedicle screws placed, the total number of vertebral levels fused, and the type of surgical approach (R(2) = 0.35, p

Analysis of segmental cervical spine vertebral motion after prodisc-C cervical disc replacement.

STUDY DESIGN: Retrospective study of patients enrolled in a prospective randomized Food and Drug Administration trial with single level cervical disc replacement (CDR) with the ProDisc-C (Synthes, Paoli, PA). OBJECTIVE: Evaluate the segmental range of motion (ROM) in the cervical spine pre- and postoperative after CDR. SUMMARY OF BACKGROUND INFORMATION: Each cervical level is believed to have its own biomechanical characteristics, ultimately leading to different sagittal and lateral ROM. Our understanding of the factors that influence motion after CDR continues to change and expand. METHODS: One hundred sixty-four patients with single level ProDisc-C arthroplasty were evaluated radiographically using Medical Metrics (QMATM, Medical Metrics, Inc., Houston, TX). Pre- and postoperative disc height and ROM were measured from standing lateral and flexion-extension radiographs. Of these 164 patients, 44 had a CDR at C6/C7, 96 at C5/C6, 18 at C4/C5, and 6 at C3/C4. The mean follow-up was of 24 months. Statistical analysis evaluated the difference in mean ROM between the groups. RESULTS: Before surgery, C4/C5 had more sagittal ROM compared with C3/C4, C5/C6, and C6/C7 (P < 0.001.) Before surgery, C4/C5 also had more lateral ROM compared with C3/C4, C5/C6, and C6/C7 (P = 0.015). After surgery, there were no significant differences in sagittal and lateral ROM between C3/C4, C4/C5, C5/C6, and C6/C7. The delta (difference between pre- and postoperative) proved that the C4/C5 CDR actually lost sagittal ROM (-2.5 degrees ) compared with the other levels, which gained sagittal ROM, C3/C4 (0.9 degrees ), C5/C6 (1.8 degrees ), and C6/C7 (1.6 degrees ); P = 0.037. There was no significant difference in the delta lateral ROM between the segments: C3/C4, C4/C5, C5/C6, and C6/C7. CONCLUSION: CDR approximates the different segmental sagittal and lateral ROM. Although C4/C5 had negative delta ROM in the sagittal and lateral planes, it provided a satisfactory final ROM. Long-term clinical outcome studies are needed to properly evaluate if these differences could ultimately affect the patients everyday life.