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Objective To evaluate preoperative disability’s influence on patient-reported outcomes (PROs) following surgery for degenerative spondylolisthesis (DS). Methods DS patients who underwent surgical intervention were retrospectively identified from a single-surgeon spine registry. Cohorts based on Oswestry Disability Index (ODI) < 41 (milder disability) and ≥ 41 (severe disability) were created. Demographic differences were accounted for with 1:1 propensity score matching. For the matched sample, perioperative and PRO data were additionally collected. PROs assessed included mental health, physical function, pain, and disability. Pre- and up to 2-year postoperative PROs were utilized. Average time to final follow-up was 15.7 ± 8.8 months. Improvements in PROs and minimal clinically important difference (MCID) rates were calculated. Continuous variables were compared through Student t-test and categorical variables were compared through chi-square tests. Results Altogether, 214 patients were included with 77 in the milder disability group. The severe disability group had worse postoperative day (POD) 1 pain scores and longer hospital stays (p ≤ 0.038, both). The severe disability group reported worse outcomes pre- and postoperatively (p < 0.011, all), but had greater average improvement in 12-item Short Form health survey mental composite score (SF-12 MCS), 9-Item Patient Health Questionnaire (PHQ-9), visual analogue scale (VAS)-back, and ODI by 6 weeks (p ≤ 0.037, all) and PHQ-9, VAS-back and ODI by final follow-up (p ≤ 0.015, all). The severe disability cohort was more likely to achieve MCID for SF-12 MCS, PHQ-9, and ODI (p ≤ 0.003, all). Conclusion Patients with greater baseline disability report higher POD 1 pain and discharge later than patients with milder disability. While these patients report inferior physical/mental health before and after surgery, they report greater improvements in mental health and disability postoperatively.

Objective To evaluate the effect of Veterans RAND 12-item health survey mental composite score (VR-12 MCS) on postoperative patient-reported outcome measures (PROMs) after undergoing lateral lumbar interbody fusion. Methods Retrospective data from a single-surgeon database created 2 cohorts: patients with VR-12 MCS ≥ 50 or VR-12 MCS < 50. Preoperative, 6-week, and final follow-up (FF)- PROMs including VR-12 MCS/physical composite score (PCS), 12-item Short Form health survey (SF-12) MCS/PCS, Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF), Patient Health Questionnaire-9 (PHQ-9), visual analogue scale (VAS)-back/leg pain (VAS-BP/LP), and Oswestry Disability Index (ODI) were collected. ∆6-week and ∆FF-PROMs were calculated. Minimal clinically important difference (MCID) achievement rates were determined from established cutoffs from the literature. For intercohort comparison, chi-square analysis was used for categorical variables, and Student t-test for continuous variables. Results Seventy-nine patients were included; 25 were in VR-12 MCS < 50. Mean postoperative follow-up time was 17.12 ± 8.43 months. The VR-12 MCS < 50 cohort had worse VR-12 PCS, SF-12 MCS, PROMIS-PF, PHQ-9, VAS-BP, and ODI scores preoperatively (p ≤ 0.014, all), worse VR-12 MCS/PCS, SF-12 MCS, PROMIS-PF, PHQ-9, and ODI scores at 6-week postoperatively (p ≤ 0.039, all), and worse VR-12 MCS, SF-12 MCS, PROMIS-PF, PHQ-9, VAS-BP, VAS-LP, and ODI scores at FF (p ≤ 0.046, all). The VR-12 MCS < 50 cohort showed greater improvement in VR-12 MCS and SF-12 MCS scores at 6 weeks and FF (p ≤ 0.005, all). The VR-12 MCS < 50 cohort experienced greater MCID achievement for VR-12 MCS, SF-12 MCS, and PHQ-9 (p ≤ 0.006, all). Conclusion VR-12 MCS < 50 yielded worse mental health, physical function, pain and disability postoperatively, yet reported greater improvements in magnitude and MCID achievement for mental health.

Study Design Retrospective cohort. Purpose To assess preoperative arm pain severity influence on postoperative patient-reported outcomes measures (PROMs) and minimal clinically important difference (MCID) achievement following single-level anterior cervical discectomy and fusion (ACDF). Overview of Literature There is evidence that preoperative symptom severity can affect postoperative outcomes. Few have evaluated this association between preoperative arm pain severity and postoperative PROMs and MCID achievement following ACDF. Methods Individuals undergoing single-level ACDF were identified. Patients were grouped by preoperative Visual Analog Scale (VAS) arm ≤8 vs. >8. PROMs collected preoperatively and postoperatively included VAS-arm/VAS-neck/Neck Disability Index (NDI)/12-item Short Form (SF-12) Physical Composite Score (PCS)/SF-12 mental composite score (MCS)/Patient-Reported Outcomes Measurement Information System physical function (PROMIS-PF). Demographics, PROMs, and MCID rates were compared between cohorts. Results A total of 128 patients were included. The VAS arm ≤8 cohort significantly improved for all PROMs excepting VAS arm at 1-year/2-years, SF-12 MCS at 12-weeks/1-year/2-years, and SF-12 PCS/PROMIS-PF at 6-weeks, only (p≤0.021, all). The VAS arm >8 cohort significantly improved for VAS neck at all timepoints, VAS arm from 6-weeks to 1-year, NDI from 6-weeks to 6-months, and SF-12 MCS/PROMIS-PF at 6-months (p≤0.038, all). Postoperatively, the VAS arm >8 cohort had higher VAS-neck (6 weeks/6 months), VAS-arm (12 weeks/6 months), NDI (6 weeks/6 months), lower SF-12 MCS (6 weeks/6 months), SF-12 PCS (6 months), and PROMIS-PF (12 weeks/6 months) (p≤0.038, all). MCID achievement rates were higher among the VAS arm >8 cohort for the VAS-arm at 6-weeks/12-weeks/1-year/overall and NDI at 2 years (p≤0.038, all). Conclusions Significance in PROM score differences between VAS arm ≤8 vs. >8 generally dissipated at the 1-year and 2-year time-point, although higher preoperative arm pain patients suffered from worse pain, disability, and mental/physical function scores. Furthermore, clinically meaningful rates of improvement were similar throughout the vast majority of timepoints for all PROMs studied.

Background: A growing emphasis on antibiotic stewardship has led to extensive literature regarding antibiotic use in spine surgery for surgical prophylaxis and the treatment of spinal infections. Purpose: This article aims to review principles of antibiotic stewardship, evidence-based guidelines for surgical prophylaxis and ways to optimize antibiotics use in the treatment of spinal infections. Methods: A narrative review of several society guidelines and spine surgery literature was conducted. Results: Antibiotic stewardship in spine surgery requires multidisciplinary investment and consistent evaluation of antibiotic use for drug selection, dose, duration, drug-route, and de-escalation. Developing effective surgical prophylaxis regimens is a key strategy in reducing the burden of antibiotic resistance. For treatment of primary spinal infection, the diagnostic work-up is vital in tailoring effective antibiotic therapy. The future of antibiotics in spine surgery will be highly influenced by improving surgical technique and evidence regarding the role of bacteria in the pathogenesis of degenerative spinal pathology. Conclusions: Incorporating evidence-based guidelines into regular practice will serve to limit the development of resistance while preventing morbidity from spinal infection. Further research should be conducted to provide more evidence for surgical site infection prevention and treatment of spinal infections.

Study Design Retrospective study. Purpose To compare perioperative outcomes, patient-reported outcome measures (PROMs), and minimal clinically important difference (MCID) achievement rates for an obese patient cohort between single-level minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) vs. anterior lumbar interbody fusion (ALIF). Overview of Literature To the best of our knowledge, no study has compared the outcomes of MIS TLIF and ALIF in an obese population. Methods Obese patients (body mass index [BMI] ≥30.0 kg/m2) who underwent single-level MIS TLIF or ALIF at L5/S1 were included in the study. Demographic/perioperative variables, presenting patient pathology, and 1-year arthrodesis statistics were collected. PROM scores for Visual Analog Scale (VAS) back/leg, Oswestry Disability Index, 12-item Short Form Physical Composite Scale, and Patient-Reported Outcome Measurement Information System Physical Function (PROMIS-PF) were collected from preoperative and postoperative (6 weeks, 12 weeks, 6 months, 1 year, 2 years) PROMIS-PF. The obese patients were classified based on the procedure they underwent (MIS TLIF vs. ALIF). Results The criteria were met by 210 patients in total. After coarsened exact matching for Charlson comorbidity index score, degenerative spondylolisthesis, isthmic spondylolisthesis, degenerative scoliosis, foraminal stenosis, insurance, male, and ethnicity, 94 obese patients were included in the total cohort, with 59 receiving MIS TLIF and 35 receiving ALIF. ALIF recipients had higher PROMIS-PF scores at 6 weeks (p=0.014) and 12 weeks (p=0.030), as well as a higher VAS leg at 2 years (p=0.017). Following multiple regression accounting for differences in baseline BMI, only the 6-week PROMIS-PF significantly differed (p=0.028), with no other intergroup differences in mean PROMs between fusion types. Aside from a significantly higher 6-week MCID achievement rate for PROMIS-PF among ALIF recipients (p=0.006), no differences in attainment were observed. Conclusions There were no statistically significant differences in perioperative characteristics, fusion rates, PROMs, or MCID achievement between obese patients receiving MIS TLIF vs. ALIF. As a result, our findings indicate that MIS TLIF and ALIF at L5/S1 are equally effective in an obese patient population.

Study Design This was a retrospective cohort study. Purpose This study investigated the influence of preoperative mental health on patient-reported outcome measures (PROMs) and minimal clinically important difference (MCID) among workers’ compensation (WC) recipients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). Overview of Literature No studies have evaluated the impact of preoperative mental functioning on outcomes following MIS TLIF among WC claimants. Methods WC recipients undergoing single-level MIS TLIF were identified. PROMs of Visual Analog Scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), 12-item Short Form Physical and Mental Composite Scale (SF-12 PCS/MCS), and Patient-Reported Outcomes Measurement Information System Physical Function evaluated subjects preoperatively/postoperatively. Subjects were grouped according to preoperative SF-12 MCS:

Study Design Retrospective cohort. Purpose To evaluate the validity of established severity thresholds for Neck Disability Index (NDI) among patients undergoing anterior cervical discectomy and fusion (ACDF) or cervical disc arthroplasty (CDA). Overview of Literature Few studies have examined the validity of established NDI threshold values among patients undergoing ACDF or CDA. Methods A surgical database was reviewed to identify patients undergoing cervical spine procedures. Demographics, operative characteristics, comorbidities, NDI, Visual Analog Scale (VAS), and 12-item Short Form (SF-12) physical and mental composite scores (PCS and MCS) were recorded. NDI severity was categorized using previously established threshold values. Improvement from preoperative scores at each postoperative timepoint and convergent validity of NDI was evaluated. Discriminant validity of NDI was evaluated against VAS neck and arm and SF-12 PCS and MCS. Results All 290 patients included in the study demonstrated significant improvements from baseline values for all patient-reported outcome measures (PROMs) at all postoperative timepoints (p

The minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a popular surgical technique for lumbar arthrodesis, widely considered to hold great efficacy while conferring an impressive safety profile through the minimization of soft tissue damage. This elegant approach to lumbar stabilization is the byproduct of several innovations throughout the past century. In 1934, Mixter and Barr’s paper in the New England Journal of Medicine elucidated the role of disc herniation in spinal instability and radiculopathy, prompting surgeons to explore new approaches and instruments to access the disc space. In 1944, Briggs and Milligan published their novel technique, the posterior lumbar interbody fusion (PLIF), involving continuous removal of vertebral bone chips and replacement of the disc with a round bone peg. The following decades witnessed several PLIF modifications, including the addition of long pedicle screws. In 1982, Harms and Rolinger sought to redefine the posterior corridor by approaching the disc space through the intervertebral foramen, establishing the transforaminal lumbar interbody fusion (TLIF). In the 1990s, lumbar spine surgery experienced a paradigm shift, with surgeons placing increased emphasis on tissue-sparing minimally invasive techniques. Spurred by this revolution, Foley and Lefkowitz published the novel MIS-TLIF technique in 2002. The MIS-TLIF has demonstrated comparable surgical outcomes to the TLIF, with an improved safety profile. Here, we present a view into the history of the posterior-approach treatment of the discogenic radiculopathy, culminating in the MIS-TLIF. Additionally, we evaluate the hallmark characteristics, technical variability, and reported outcomes of the modern MIS-TLIF and take a brief look at technologies that may define the future MIS-TLIF.

Objective The American Society of Anesthesiologists (ASA) physical status classification has been used to risk stratify surgical candidates. Our study compares outcomes of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) procedures based on preoperative ASA physical status classification. Methods A surgical registry was reviewed for primary, single-level MIS TLIF patients. Patients were categorized by preoperative ASA physical status classification: ASA I, ASA II, ASA III+. Perioperative complications were compared among groups. Patient-reported outcome measures (PROMs) for back pain, leg pain, physical function, and disability were recorded preoperatively and at 6-week, 12-week, 6-month, 1-year, and 2-year postoperative timepoints. PROM improvement from baseline (ΔPROM) and minimum clinically important difference (MCID) achievement was calculated for each timepoint and compared among groups. MCID achievement was determined as ΔPROMs that surpassed previously established MCID values. Results Of the 487 patients, 64 had an ASA classification of I, whereas 336 had an ASA of II, and 87 had an ASA of III or greater. Rates of complications were not associated with ASA classification (all p>0.050). Neither mean PROM scores nor ΔPROM scores were significantly associated with ASA classification at any timepoint (all p>0.050). MCID achievement was significantly associated with ASA classification for back pain at 1 year only (p=0.041). Overall MCID achievement was not significantly associated with ASA classification for any PROM (p>0.050). Conclusion While ASA classification has been commonly used to risk stratify surgical candidates for spinal procedures, patients with an ASA of III or greater may be able to achieve similar long-term outcomes following MIS TLIF given proper selection criteria.

Study Design Retrospective cohort. Purpose To investigate the impact of meeting a patient’s preoperative expectations for back or leg pain or the achievement of minimum clinically important difference (MCID) on patient satisfaction following lumbar fusion. Overview of Literature Few studies have compared if MCID achievement or meeting preoperative expectations for pain reduction affects patient satisfaction. Methods A surgical database was reviewed for eligible patients who underwent lumbar fusion. Patient satisfaction and Visual Analog Scale (VAS) for back and leg pain were the outcomes of interest. Meeting expectations was calculated as a difference of ≤0 between preoperative expectations and postoperative VAS scores. MCID achievement was calculated by comparing changes in VAS scores with established values. Meeting preoperative expectations or MCID achievement as predictors of patient satisfaction was evaluated using regression analysis. Results A total of 134 patients were included in this study. Patients demonstrated significant improvements in VAS back and VAS leg (p

Objective Patient-Reported Outcomes Measurement Information System (PROMIS) is a validated tool for assessing patient-reported outcomes in spine surgery. However, PROMIS is vulnerable to nonresponse bias. The purpose of this study is to characterize differences in patient-reported outcome measure scores between patients who do and do not complete PROMIS physical function (PF) surveys following lumbar spine surgery. Methods A prospectively maintained database was retrospectively reviewed for primary, elective lumbar spine procedures from 2015 to 2019. Outcome measures for Patient Health Questionnaire-9 (PHQ-9), visual analogue scale (VAS) back & leg, Oswestry Disability Index (ODI), and 12-item Short Form health survey physical composite summary (SF-12 PCS) were recorded at both preoperative and postoperative (6 weeks, 12 weeks, 6 months, 1 year, 2 years) timepoints. Completion rates for PROMIS PF surveys were recorded and patients were categorized into groups based on completion. Differences in mean scores at each timepoint between groups was determined. Results Eight hundred nine patients were included with an average age of 48.1 years. No significant differences were observed for all outcome measures between PROMIS completion groups preoperatively. Postoperative PHQ-9, VAS back, VAS leg, and ODI scores differed significantly between groups through 1 year (all p < 0.05). SF-12 PCS differed significantly only at 6 weeks (p = 0.003). Conclusion Patients who did not complete PROMIS PF surveys had significantly poorer outcomes than those that did in terms of postoperative depressive symptoms, pain, and disability. This suggests that patients completing PROMIS questionnaires may represent a healthier cohort than the overall lumbar spine population.

Objective The clinical utility of anterior cervical plating for anterior cervical discectomy and fusion (ACDF) procedures remains controversial. This study aims to compare the impact of cervical plating on achievement of minimum clinically important difference (MCID) up to 2 years following ACDF. Methods Patients undergoing primary, single-level ACDF procedures were grouped based on whether their procedure included application of an anterior cervical plate. Demographics, preoperative spinal diagnoses, operative characteristics, and patient-reported outcome measures (PROMs) were compared between plating groups. Achievement of an MCID was assessed using the following previously established thresholds: 12-item Short Form health survey physical component summary (SF-12 PCS) 8.1, visual analogue scale (VAS) neck 2.6, VAS arm 4.1, Neck Disability Index (NDI) 8.5. Rates of MCID achievement were compared between groups. Results The cohort included 192 patients of whom 102 received plating and 90 received no plating. Plating status was significantly associated with Charlson Comorbidity Index and insurance status. Operative duration and estimated blood loss were significantly greater for the plating group. Both groups demonstrated significant improvements at the majority of postoperative timepoints. Significant intergroup differences in PROM improvement were demonstrated for VAS neck and NDI at 6 weeks. Rates of MCID achievement differed significantly between groups for NDI at 6 weeks, and 12 weeks, and SF-12 PCS overall. Conclusion Patients improved significantly in terms of pain, disability and physical function, regardless of plating status, and with the exception of early neck pain and disability, these improvements were similar between groups. Patients that underwent plating as part of their ACDF procedure achieved an MCID for physical function at lower rates overall.

Objective Minimally invasive techniques and multimodal analgesia protocols have made spine surgery in the outpatient setting increasingly feasible. A number of spinal procedures have been documented in the outpatient setting, though the feasibility of lateral lumbar interbody fusion (LLIF) on an ambulatory basis has not been thoroughly assessed. To present a clinical case series of patients undergoing LLIF in the outpatient setting. Methods A prospectively maintained surgical database was retrospectively reviewed to identify patients undergoing outpatient spine procedures with an enhanced multimodal analgesia protocol from October 2016 to February 2021. Patient demographics, medical and spinal diagnoses, procedural characteristics, operative duration, estimated blood loss (EBL), postoperative length of stay (LOS), postoperative pain scores, postoperative narcotic consumption, and incidence of any intra- or postoperative complications were collected. The state’s prescription monitoring program was queried to assess rates of filling narcotic prescriptions >6 weeks following surgery. Results A total of 24 LLIF patients were included. Mean postoperative pain score was 5.8, and mean postoperative narcotic consumption was 26.8 oral morphine equivalents. All patients were discharged on the same day of surgery. No postoperative complications were observed. After the 6-week postoperative timepoint, 16.7% of patients filled a prescription for tramadol, 8.3% for hydrocodone, 4.2% for hydromorphone, 4.2% for cyclobenzaprine, and 4.2% for alprazolam. Conclusion This clinical case series demonstrates that LLIF can be both safe and feasible in the outpatient setting, with minimal narcotic medication dependence in the postoperative period.

Objective This study aims to compare the impact of achieving an MCID or meeting preoperative expectations on patient satisfaction following cervical spine procedures. Methods A surgical database was retrospectively reviewed for cervical spine surgery patients from 2016 to 2020. Inclusion criteria were primary or revision, single- or multilevel cervical disc arthroplasty or anterior cervical discectomy and fusions (ACDF). Visual analogue scale (VAS) neck and arm pain was assessed preoperatively and postoperatively (6-week, 12-weeks, 6-months, 1-year). Preoperative patient expectation and postoperative satisfaction were recorded. MCID achievement was determined using previously established values. Expectations met and MCID achievement were compared as possible predictors of satisfaction. Results One hundred and six cervical spine patients were included. Both meeting expectations and achieving MCID were significant predictors of satisfaction for arm pain at 6-weeks and 12-weeks (all p≤0.007). Achieving MCID significantly predicted satisfaction for neck pain at all timepoints (all p≤0.007) and meeting expectations predicted satisfaction for neck pain at 6-weeks, 12-weeks, and 1-year (all p≤0.003). Comparison of coefficients revealed no significant difference in effect size between meeting expectations and achievement of MCID as predictors of patient satisfaction (all p>0.050). Conclusion MCID achievement and meeting expectations were significant predictors of satisfaction for neck pain and short-term arm pain. Both measures may be similarly useful for interpretation of patient outcomes and the optimal choice of metric may depend on practice-specific factors.

Objective To evaluate dysphagia outcomes using the swallowing quality of life (SWAL-QOL) questionnaire between patients undergoing cervical disk arthroplasty (CDA) or anterior cervical discectomy and fusion (ACDF). Methods Patient-reported outcome measures (PROMs) were collected using SWAL-QOL, VAS, NDI, and SF-12 PCS. All measures were recorded preoperatively to 6-month postoperatively. Patients were grouped according to cervical procedure and instrumentation used. Differences in PROMs and SWAL-QOL domains were evaluated by t-test and one-way ANOVA with post-hoc testing, respectively. Simple linear regression was employed to evaluate the relationship between number of levels operated on and postoperative outcomes. Results 161 patients were included. CDA patients had significantly worse SWAL-QOL scores at 6-months. Preoperative VAS neck was significantly worse for patients who underwent either an ACDF procedure with a stand-alone cage or CDA as compared to patients who underwent an ACDF with anterior plating. At 6-months postoperatively, CDA patients reported a significantly worse “fatigue” score compared to ACDF patients. At 6-months postoperatively, ACDF patients reported a significantly better “sleep” scores compared to CDA patients with both recipients of an anterior plate and stand-alone cage reporting significantly better scores compared to the CDA cohort (p=0.024; p

Study Design Retrospective cohort. Purpose This study aimed to assess the relationship between preoperative narcotic consumption and patient-reported outcomes (PRO) in patients undergoing minimally invasive (MIS) lumbar decompression (LD). Overview of Literature Previous studies report negative effects of narcotic consumption on perioperative outcomes and recovery; however, its impact on quality of life and surgical outcomes is not fully understood. Methods A surgical database was retrospectively reviewed for patients undergoing primary, single-level MIS LD from 2013 to 2020. Patients lacking preoperative narcotic consumption data were excluded. Demographics, spinal pathologies, and operative characteristics were collected. Patients were grouped based on preoperative narcotic consumption. Patient Health Questionnaire-9 (PHQ-9), Visual Analog Scale (VAS) for back and leg, Oswestry Disability Index (ODI), 12-item Short Form Physical Component Summary, and Patient-Reported Outcomes Measurement Information System physical function (PROMIS-PF) were collected preoperatively and postoperatively. Preestablished values were used to calculate achievement of minimum clinically important difference (MCID). Differences in mean PROs and MCID achievement between groups were evaluated. Results The cohort was 453 patients; 184 used preoperative narcotics and 269 did not. Significant differences were found in American Society of Anesthesiologists classification, ethnicity, insurance type, and estimated blood loss between groups. Significant differences were also found in preoperative PHQ-9, VAS leg, ODI, and PROMIS-PF between groups (all p0.05). A higher rate of MCID achievement was associated with the narcotic group for PHQ-9 and PROMIS-PF at 6 weeks (both p≤0.050), VAS leg at 1 year (p=0.009), and overall for ODI and PHQ-9 (both p≤0.050). Conclusions Preoperative narcotic consumption was associated with worse preoperative depression, leg pain, disability, and physical function. In patients consuming preoperative narcotics, a higher proportion achieved an overall MCID for disability and depressive symptoms. Patients taking preoperative narcotic medications may report significantly worse preoperative PROs but demonstrate greater improvements in postoperative disability and mental health.

Objective To assess the impact of bilateral versus unilateral interbody cages on outcomes for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) procedures. Methods A retrospective review for primary, elective, single-level MIS TLIF procedures with bilateral posterior instrumentation from 2008–2020 was performed. Patients were grouped according to unilateral or bilateral interbody cage use. Procedures performed without static interbody cages or indicated for trauma, infection, malignancy were excluded. Patient-reported outcomes (PROs) included visual analogue scale (VAS), Oswestry Disability Index, 12-item Short Form health survey physical composite score (SF-12 PCS), PatientReported Outcome Measurement Information System physical function (PROMIS-PF). PROs were collected preoperatively and postoperatively. Change in PROs (Δ) was calculated and compared between groups. Achievement of minimum clinically important difference (MCID) was calculated using established values from the literature. Achievement rates were compared between groups using logistic regression. Results The study included 151 patients, with 111 unilateral and 40 bilateral cage placements. Charlson Comorbidity Index, diabetes, and insurance status differed between groups (p < 0.050). Prevalence of degenerative and isthmic spondylolisthesis (both p ≤ 0.002), operative level (p = 0.003), and postoperative length of stay (p = 0.022) significantly differed between groups. The unilateral group had lower 1-year arthrodesis rates (p = 0.035). Preoperative VAS leg (p = 0.017) and SF-12 PCS (p = 0.045) were worse for the unilateral group. ΔPROMIS-PF was greater for the bilateral group at 2 years (p = 0.001). Majority of patients achieved an overall MCID for all PROs, except VAS leg (bilateral group). Conclusion While preoperative status and postoperative arthrodesis rates differed, patients achieved an MCID at similar rates regardless of use of unilateral or bilateral cages.

Objective To assess change in Patient-Reported Outcome Measures (PROM) as predictors for revision lumbar decompression (LD). Methods Patients who underwent primary, single or multilevel LD were retrospectively reviewed. Patients were categorized according to whether or not they underwent revision LD within 2 years of the primary procedure. Visual analogue scale (VAS), Oswestry Disability Index (ODI), 12-item Short Form Health Survey and 12-item Veterans RAND physical component score (SF-12 PCS and VR-12 PCS), and Patient-Reported Outcome Measurement Information System physical function (PROMIS-PF) were recorded. Delta PROM scores were evaluated for differences between groups and as a risk factor for a revision LD. Results The study included 135 patients, 91 undergoing a primary procedure only and 44 undergoing a primary and revision procedure. Matched patients did not demonstrate any significant differences in demographics or perioperative characteristics. Patients who underwent a revision had a mean time to revision of 7.4 ± 5.7 months. Primary cohort significantly improved for all PROMs (all p < 0.05), while the primary plus revision cohort significantly improved for VAS back, ODI, and PROMIS-PF (all p < 0.05). However, cohorts differed in VAS back and PROMIS-PF (p < 0.05). Delta PROMs were not a significant risk factor for revision except at 6 months for PROMIS-PF (p = 0.024). Conclusion LD has been associated with reliable outcomes, but early identification of patients at risk for revision is critical. This study suggests that tools such as PROMIS-PF may serve a role in predicting who is at risk and the 6-month follow-up period may be valuable for counseling patients who are not experiencing improvement.

Objective This study aims to detail the association between comorbidity burden and achieving minimum clinically important difference (MCID) following anterior cervical discectomy and fusion (ACDF). Methods A prospective surgical registry was retrospectively reviewed. Patients with missing preoperative Patient-Reported Outcomes Measurement Information System physical function (PROMIS PF) were excluded. Patients were stratified by Charlson Comorbidity Index (CCI): no comorbidities = 0 point; low CCI = 1–2 points; high CCI = ≥ 3 points. Demographic and perioperative characteristics were collected and evaluated for differences. Visual analogue scale (VAS), 12-item Short Form health survey (SF-12), and PROMIS PF were collected pre- and postoperatively and assessed for differences. Differences in achievement of MCID were compared using established values: VAS neck = 2.6, VAS arm = 4.1, NDI = 8.5, SF-12 physical composite score (SF-12 PCS) = 8.1, PROMIS PF = 4.5. Results One hundred twenty-five ACDF patients were included: 37 had no comorbidities, 64 with low CCI, and 24 with high CCI. Higher CCI groups were older, nonsmokers, diabetic, arthritic, hypertensive, and had cancer. Multilevel fusions, operative time, length of stay, and later discharge day were associated with high CCI. VAS neck differed preoperatively by group. SF-12 PCS and PROMIS PF were inversely associated with CCI groups. CCI did not impact achievement of MCID for all outcomes. A lower rate of reaching MCID was demonstrated at 3 months for SF-12 PCS. Conclusion Regardless of comorbidity burden, patients undergoing ACDF for cervical pathology demonstrated a similar rate of achieving MCID for VAS neck, VAS arm, NDI, and PROMIS PF. Regardless of CCI score, ACDF can have a significant benefit for patients.

Objective Our study aims to evaluate the impact of severity of preoperative Neck Disability Index (NDI) on postoperative patient-reported outcome measures (PROMs). Methods A retrospective review of primary, elective, single or multilevel anterior cervical discectomy and fusion or cervical disc arthroplasty procedures between 2013 and 2019 was performed. Visual analogue scale (VAS) neck and arm, NDI, 12-item Short Form physical and mental composite score (SF-12 PCS and MCS), Patient-Reported Outcome Measurement Information System physical function, and 9-item Patient Health Questionnaire (PHQ-9) were collected preoperatively and postoperatively. Patients were categorized by preoperative NDI: none-to-mild disability (< 30); moderate disability (≥ 30 to < 50); severe disability (≥ 50 to < 70); complete disability (≥ 70). The impact of preoperative NDI on PROM scores and minimum clinically important difference (MCID) achievement rates were evaluated. Results The cohort included 74 patients with none-to-mild disability, 95 moderate, 76 severe, and 17 with complete disability. Patients with greater preoperative disability demonstrated significantly different scores for NDI, VAS neck, SF-12 MCS, and PHQ-9 at all timepoints (p < 0.001). Patients with more severe disability demonstrated different magnitudes of improvement for NDI (all p < 0.001), VAS neck (p ≤ 0.009), VAS arm (p = 0.025), and PHQ-9 (p ≤ 0.011). The effect of preoperative severity on MCID achievement was demonstrated for NDI and for PHQ-9 (p ≤ 0.007). Conclusion Patients with severe neck disability demonstrated differences in pain, disability, physical and mental health. MCID achievement also differed by preoperative symptoms severity. Patients with more severe neck disability may be limited to the degree of improvement in quality of life but perceive them as significant changes.

Objective The Patient Health Questionnaire-9 (PHQ-9) is a screening tool for evaluating depressive symptoms. Research is scarce regarding the validity and correlation of PHQ-9 scores with other patient-reported outcomes of mental health after minimally invasive lumbar discectomy (MIS LD). We aim to validate PHQ-9 as a metric for assessing mental health in MIS LD patients. Methods A database was retrospectively reviewed for patients who underwent elective, single-level MIS LD. Patients were excluded if they had incomplete preoperative PHQ-9, 12-item Short Form Health Survey (SF-12), or Veterans RAND 12-item health survey (VR-12). Survey scores were collected preoperatively and postoperatively through 1 year. Mean scores were used to calculate postoperative improvement from preoperative scores. Correlation of PHQ-9 with SF-12 mental composite score (MCS) and VR-12 MCS scores was also calculated. Correlation strength was assessed by the following categories: 0.1 ≤ |r| < 0.3 = low; 0.3 ≤ |r| < 0.5 = moderate; |r| ≥ 0.5 = strong. Results A total of 239 patients underwent single-level MIS LD. PHQ-9, VR-12 MCS, and SF-12 MCS all demonstrated statistically significant increases from preoperative scores at all postoperative timepoints (p ≤ 0.001). SF-12 MCS and VR-12 MCS were each observed to have strong and significant correlations with PHQ-9 at all timepoints when evaluated with both Pearson correlation coefficients and partial correlation coefficients. Conclusion We observed that PHQ-9, SF-12 MCS and VR-12 MCS all significantly improve following lumbar discectomy and that PHQ-9 scores strongly correlated with these previously established measures. Our results substantiate evidence from other surgical fields that PHQ-9 scores are a valid tool to evaluate pre- and postsurgical depressive symptoms.

Objective Our study aims to evaluate the correlation of Patient-Reported Outcomes Measurement Information System physical function (PROMIS PF) with legacy patient-reported outcome measures (PROMs) among patients undergoing anterior cervical discectomy and fusion (ACDF). Methods A prospectively maintained database was retrospectively reviewed for ACDF surgeries performed between May 2015 and September 2017. Inclusion criteria were primary elective, single- or multilevel ACDFs for degenerative spinal pathology. Patients lacking preoperative or 2-year PROMIS PF surveys were excluded. Mean scores were calculated for visual analogue scale (VAS) neck, VAS arm, Neck Disability Index (NDI), 12-Item Short Form Physical Component Score (SF-12 PCS), and PROMIS PF at preoperative and 6-week, 12-week, 6-month, 1-year, and 2-year postoperative timepoints. A t-test and Pearson correlation coefficient were utilized to evaluate score improvement and PROM relationships respectively. Results The 50 subject cohort was 60.0% male, 50% obese (body mass index ≥ 30 kg/m2) and had an average age of 50.9 years. Significant improvements were demonstrated for VAS neck and NDI at all postoperative timepoints (p < 0.001) and for SF-12 and PROMIS PF at all timepoints except 6 weeks (p ≤ 0.025). VAS arm improvement was seen up to 1 year (p ≤ 0.016). PROMIS PF demonstrated strong correlations with NDI and SF-12 PCS at all evaluated timepoints and with VAS neck at all postoperative timepoints except 6 weeks (all p < 0.01). Conclusion PROMIS PF was strongly correlated with pain, disability, and physical function up to 2 years for patients undergoing ACDF. Our results support the long-term validity of PROMIS PF for measurement of patient-reported physical function among ACDF cohorts.

Objective There is a scarcity of research evaluating gender differences in depressive symptoms among patients undergoing cervical surgery. This study investigated gender differences with regard to depressive symptom severity, measured by Patient Health Questionnaire-9 (PHQ-9), in patients following anterior cervical discectomy and fusion (ACDF) or artificial disc replacement (ADR). Methods A prospectively maintained surgical registry was retrospectively reviewed for eligible spine surgeries. Depressive symptom severity was evaluated by PHQ-9 at both preand postoperative timepoints (e.g. , 6 weeks, 12 weeks, 6 months, 1 year, and 2 years). A chi-square test and Student t-test evaluated differences between the gender for demographic and operative variables where appropriate. Differences between the gender subgroup mean PHQ-9 scores were assessed using a t-test pre- and postoperatively (e.g. , 6 weeks, 12 weeks, 6 months, and 1 year) and a paired t-test was used to assess differences from preoperative scores at each postoperative time point. Results A total of 170 subjects underwent 125 ACDFs and 45 ADRs. Both pre- and postoperative timepoints demonstrated no significant differences between mean PHQ-9 scores by gender. Female patients demonstrated statistically significant improvement in PHQ-9 scores at 6 weeks, and 12 weeks, but not through 2 years. Male patients demonstrated statistically significant improvement in PHQ-9 scores at 6 weeks, 12 weeks, 6 months, 1 year, and 2 years. Conclusion Although there were no significant differences between mean PHQ-9 score between the genders, there was a difference in magnitude of improvement. Females had a significant improvement in depressive symptom severity over baseline at the 6- and 12-week timepoints only, whereas males had significant improvement through 2 years postoperatively.

Objective While visual analogue score (VAS) metrics are among the most universally adopted patient-reported outcome measures (PROMs), there is limited research on the influence of back and leg pain on the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) scores. Here we assess the association of VAS back and VAS leg scores with PROMIS PF in the setting of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). Secondarily, we determine if PROMIS PF is more influenced by back or leg pain. Methods A prospective surgical registry was reviewed from May 2015 to November 2018. Inclusion criteria were primary, single-level MIS TLIFs. We excluded multilevel procedures and patients without preoperative PROMs. Pre- and postoperative PROMIS PF, VAS back, and VAS leg scores were recorded at 6 weeks, 12 weeks, 6 months, and 1 year. A Pearson correlation evaluated PROMIS PF association with VAS back and VAS leg scores. A Fisher z-test compared correlations. Linear regression evaluated PROMIS with VAS back and VAS leg scores. Results Our cohort was comprised of 146 subjects. 40.4% were female and the average age of 51 years. VAS back demonstrated a stronger correlation than VAS leg with PROMIS PF at all timepoints. PROMIS PF scores were negatively associated with both VAS back and VAS leg at all timepoints. Fisher z-test revealed VAS back to have a stronger correlation with PROMIS PF (p = 0.025) than VAS leg. Conclusion In the setting of MIS TLIF, physical function as evaluated by PROMIS PF, had a stronger correlation with VAS back than VAS leg at 6 months. This suggests that postoperative PROMIS PF scores may be more influenced by back pain than with leg pain.

Objective This study examines the associations between preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) score, measured by PROMIS-PF and the change between pre- and postoperative PROMIS-PF scores. Methods A prospectively maintained surgical registry was retrospectively reviewed for spine surgeries between May 2015–June 2019. Inclusion criteria were primary, single-level minimally invasive transforaminal lumbar interbody fusions. Revisions, multilevel procedures, and patients missing preoperative surveys were excluded. Patients were grouped by preoperative PROMIS-PF scores of ≥ 35 and < 35, with higher scores indicating greater PF. A chi-squared and Student t-test were used to analyze categorical and continuous variables respectively. Linear regression evaluated the relationship of PROMIS-PF score improvement. Results Of the 180 subjects, 84 were in the PROMIS-PF < 35 group which had more obese patients (p < 0.001) and more males (p = 0.001). Length of stay was greater for the PROMIS-PF < 35 group (36.2 hours vs. 28.7 hours, p = 0.014). PROMIS-PF and Oswestry Disability Index scores were significantly different between subgroups at all timepoints. PROMIS-PF < 35 cohort had larger postoperative PROMIS-PF improvements at 6 weeks (p = 0.008) and 12 weeks (p = 0.003). Linear regression demonstrated a negative association between preoperative PROMIS-PF scores and improvement at 6 weeks, 12 weeks, 6 months, and 2 years (p < 0.001). PROMIS-PF < 35 demonstrated significantly lower rate of achieving minimum clinically important difference at 6 months, otherwise no difference observed throughout the 2-year follow-up. Conclusion Up to 6 months postoperatively, lower preoperative PROMIS-PF scores were associated with larger PROMIS-PF improvements. Understanding the relationship preoperative PROMIS-PF scores have with postoperative improvement may enable better patient counseling.

Objective Assess preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) scores and differences between preoperative and postoperative PROMIS-PF scores for patients undergoing anterior cervical discectomy and fusion (ACDF). Methods After Institutional Review Board approval, a prospectively maintained surgical registry was retrospectively reviewed for elective spine surgeries of nontraumatic, degenerative pathology between 2015–2018. Inclusion criteria were primary or revision, single-level ACDF procedures. Multilevel procedures and patients without preoperative surveys were excluded. A preoperative PROMIS score cutoff of 35 divided patients into PROMIS-PF score categories (e.g., ≥ 35.0, < 35.0). Categorical and continuous variables were evaluated with chi-square tests and t-tests. Linear regression analyzed PROMIS-PF score improvement. Results Eighty-six patients were selected, the high and low PROMIS-PF subgroups only differed in mean age (49.1 vs. 41.3, p = 0.002). Significant differences in PROMIS-PF scores were observed among high and low preoperative PROMIS-PF score subgroups at 6 weeks (p = 0.006), 12 weeks (p = 0.006), and 6 months (p = 0.014). Mean differences between preoperative and postoperative PROMIS-PF scores were significantly different between the high and low PROMIS-PF subgroups at 6 weeks (p = 0.041) and 1 year (p = 0.038). A significant negative association was observed between preoperative PROMIS scores and magnitude of improvement at the 6-week postoperative time point (slope = -0.6291, p < 0.001). Conclusion Patients with low preoperative PROMIS-PF scores demonstrated greater improvements at 6 weeks and 1 year. Clinicians should consider patients with low preoperative PROMIS-PF scores to be in the unique position to potentially experience larger postoperative improvement magnitudes than patients with higher preoperative PROMIS-PF scores.

Objective To assess the relationship of preoperative physical function, as measured by Patient-Reported Outcome Measurement Information System Physical Function (PROMIS PF), to improvement in mental health, as evaluated by Short Form-12 Mental Component Summary (SF-12 MCS) following anterior cervical discectomy and fusion (ACDF). Methods Patients undergoing primary ACDF were retrospectively reviewed and stratified based on preoperative PROMIS PF scores. PROMIS PF cohorts were tested for an association with demographic characteristics and perioperative variables using chi-square analysis and multivariate linear regression. Multivariate linear regression was utilized to determine the association between PROMIS PF cohorts and improvement in SF-12 MCS. Results A total of 129 one- to 3-level ACDF patients were included: 73 had PROMIS PF < 40 (“low PROMIS”) and 56 had PROMIS PF ≥ 40 (“high PROMIS”). The low PROMIS cohort reported worse mental health preoperatively and at all postoperative timepoints except for 1 year. Both cohorts had similar changes in mental health from baseline through the 6-month follow-up. However, at 1 year. postoperatively, the low PROMIS cohort had a statistically greater change in mental health score. Conclusion Patients with worse preoperative physical function reported significantly worse preoperative and postoperative mental health. However, patients with worse preoperative physical function made significantly greater improvements in mental health from baseline. This suggests that patients with worse preoperative physical function can still expect significant improvements in mental health following surgery.

Objective The relationship between bone graft technique and postoperative outcomes for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has not been well-defined. This study aims to determine the effect of iliac crest bone grafting (ICBG) on patient-reported outcomes (PROs) and complication rates following MIS TLIF. Methods Primary, single-level MIS TLIF patients were consecutively analyzed. Patients that prospectively received a percutaneous technique of ICBG were compared to patients that retrospectively received bone morphogenetic protein-2 (BMP-2). Complication rates were assessed perioperatively and up to 1 year postoperatively. Changes in Oswestry Disability Index (ODI), visual analogue scale (VAS) back, and VAS leg pain were compared. Rates of minimum clinically important difference (MCID) achievement at final follow-up for ODI, VAS back, and VAS leg scores were compared. Results One hundred forty-nine patients were included: 101 in the BMP-2 cohort and 48 in the ICBG cohort. The ICBG cohort demonstrated increases in intraoperative blood loss and shorter lengths of stay. ICBG patients also experienced longer operative times, though this did not reach statistical significance. No significant differences in complication or reoperation rates were identified. The ICBG cohort demonstrated greater improvements in VAS leg pain at 6-week and 12-week follow-up. No other significant differences in PROs or MCID achievement rates were identified. Conclusion Patients undergoing MIS TLIF with ICBG experienced clinically insignificant increases in intraoperative blood loss and did not experience increases in postoperative pain or disability. Complication and reoperation rates were similar between groups. These results suggest that ICBG is a safe option for MIS TLIF.

Objective Anterior cervical plating in anterior cervical discectomy and fusion (ACDF) procedures are associated with improved outcomes compared to stand-alone cages. However, concerns exist regarding increased rates of postoperative dysphagia following an ACDF. This study aims to quantify the effect of anterior plating on swallowing-quality of life (SWAL-QOL) scores and radiographic swelling assessments following a primary, single-level ACDF. Methods Patients retrospectively reviewed. Patients grouped into those receiving a cage or anterior plate. SWAL-QOL scores were recorded preoperatively and 6 weeks and 12 weeks postoperatively. Lateral radiographs were used to create a swelling index with a ratio of the prevertebral swelling distance to the anterior-posterior diameter of each involved vertebral body. An air index was created using the same methodology. Statistical analysis was performed using chi-square analysis and independent t-tests for categorical and continuous variables. Results Sixty-eight primary, single-level ACDF patients were included. Forty-one (60.3%) received a stand-alone cage and 27 (39.7%) received a cage with anterior plating. No differences in demographics, comorbidities, operative time, estimated blood loss, or length of hospital stay were identified between Cage and Plate cohorts. Finally, no differences were observed in postoperative SWAL-QOL scores or swelling and air indices between groups. Conclusion The results demonstrate that patients undergoing a primary, single-level ACDF with or without anterior plating experience similar operative times and lengths of stay. Patients that receive a cage with anterior plating did not experience significant increases in dysphagia as measured by the SWAL-QOL questionnaire compared to patients that received a stand-alone cage. Furthermore, radiographic assessments of swelling are comparable.

Study Design: This is a retrospective cohort study. Introduction: Spine procedures are the most expensive surgical interventions on a per-case basis. Previously, orthopedic procedures occurring later in the week have been associated with an increased length of stay (LOS) and consequent increase in costs. However, no such analysis has been performed on common spinal procedures such as minimally invasive lumbar decompression (MIS LD). The purpose of this study is to determine if there is an association between day of surgery and LOS or direct hospital costs after MIS LD. Materials and Methods: A prospectively maintained surgical database of patients who underwent primary, single, or multilevel MIS LD for degenerative spinal pathology between 2008 and 2017 was reviewed. Patients undergoing MIS LD were grouped as early in the week (Monday/Tuesday) or late in the week (Thursday/Friday). Differences in patient demographics and preoperative characteristics were compared using χ 2 analysis or Student’s t -test. Associations between date of surgery, LOS, and costs were assessed using multivariate linear regression. Results: A total of 717 patients were included. Of these, 420 (58.6%) were in the early surgery cohort and 297 (41.4%) were in the late surgery cohort. There were no differences in demographic characteristics, operative levels, operative time, blood loss, or hospital LOS between cohorts ( p > 0.05). Furthermore, there was no difference in total direct costs or specific cost categories between cohorts ( p > 0.05). Discussion: The timing of surgery within the week is not associated with differences in inpatient LOS or hospital costs following MIS LD. As such, hospitals should not alter surgical scheduling patterns to restrict these procedures to certain days within the week.

Objective This study aimed to determine the incidence of postoperative fever, the workup conducted for postoperative fever, the rate of subsequent fever-related diagnoses or complications, and the risk factors associated with fever following lumbar fusion. Methods A retrospective review of patients undergoing lumbar fusion was performed. For patients in whom fever (≥38.6°C) was documented, charts were reviewed for any fever workup or diagnosis. Multivariate regression was used to identify independent risk factors for the development of postoperative fever. Results A total of 868 patients met the inclusion criteria, of whom 105 exhibited at least 1 episode of fever during hospitalization. The first documentation of fever occurred during the first 24 hours in 43.8% of cases, during postoperative hours 24–48 in 53.3%, and later than 48 hours postoperatively in 2.9%. At least 1 component of a fever workup was conducted in 47 of the 105 patients who had fever, resulting in fever-associated diagnoses in 4 patients prior to discharge. Three patients who had fever during the inpatient stay developed complications after discharge. On multivariate analysis, operations longer than 150 minutes (relative risk [RR], 1.66; p=0.015) and narcotic consumption greater than 85 oral morphine equivalents on postoperative day 0 (RR, 1.53; p=0.038) were independently associated with an increased risk of developing postoperative fever. Conclusion The results of this study suggest that inpatient fever occurred in roughly 1 in 8 patients following lumbar fusion surgery. In most cases where a fever workup was performed, no cause of fever was detected. Longer operative time and increased early postoperative narcotic use may increase the risk of developing postoperative fever.

Context: Thoracolumbar injuries are common manifestations of spinal trauma. While non-operative therapy is indicated in certain cases of isolated injury, operative therapy via open approaches are widely utilized. Recently, minimally invasive surgical (MIS) approaches have been adapted for the management of thoracolumbar trauma in an effort to avoid the operative morbidity of open thoracolumbar procedures. Purpose: The purpose of this review is to perform a critical analysis of the literature regarding the clinical efficacy and safety of MIS procedures in the management of thoracolumbar trauma. Evidence Acquisition: PubMed and MEDLINE databases were searched for articles published on the topic of MIS treatment of traumatic thoracolumbar injuries. Studies included in this review were comprised of clinical case series, retrospective cohort studies, non-randomized prospective cohort studies, prospective randomized controlled trials, and meta-analyses. Results: The majority of published studies were retrospective clinical case series comprising level IV evidence. The majority of studies demonstrated the viability of MIS approaches as a treatment modality for thoracolumbar trauma in regards to clinical outcomes, radiographic outcomes, and complication rates. Additionally, MIS procedures were associated with reductions in operative time, intraoperative blood loss, and immediate postoperative pain. Conclusions: MIS approaches to thoracolumbar trauma are viable treatment strategies in regards to clinical efficacy and safety. While the results for MIS procedures are promising, more high-quality prospective studies are necessary in order to make definitive conclusions regarding the superiority of MIS over open surgical strategies.

Justin Munns, Daniel K Park, Kern SinghDepartment of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USAAbstract: Osteogenic protein-1 (OP-1), also known as bone morphogenetic protein-7 (BMP-7), is a protein in the TGF-β family of cellular proteins that has shown potential for application in patients undergoing spinal fusion due to its proven osteoinductive effects, particularly in patients with spondylolisthesis. OP-1 initiates numerous processes at the cellular level, acting on mesenchymal stem cells (MSCs), osteoblasts, and osteoclasts to stimulate bone growth. Animal studies of OP-1 have provided strong evidence for the ability of OP-1 to initiate ossification in posterolateral arthrodesis. Promising findings in early clinical trials with OP-1 prompted FDA approval for use in long bone nonunions in 2001 and subsequently for revision posterolateral arthrodesis in 2004 under a conditional Humanitarian Device Exemption. Larger clinical trials have recently shown no notable safety concerns or increases in adverse events associated with OP-1. However, a recent clinical trial has not conclusively demonstrated the noninferiority of OP-1 compared to autograft in revision posterolateral arthrodesis. The future of OP-1 application in patients with spondylolisthesis thus remains uncertain with the recent rejection of Premarket Approval (PMA) status by the FDA (April 2009). Further investigation of its treatment success and immunological consequences appears warranted to establish FDA approval for its use in its current form.Keywords: osteogenic protein-1, bone morphogenetic protein-7, spinal fusion

Neil Ghodadra, Kern SinghDepartment of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USAAbstract: Over one million fractures occur per year in the US and are associated with impaired healing increasing patient morbidity, stress, and economic costs. Despite improvements in surgical technique, internal fixation, and understanding of biologics, fracture healing is delayed or impaired in up to 4% of all fractures. Complications due to impaired fracture healing present therapeutic challenges to the orthopedic surgeon and often lead to chronic functional and psychological disability for the patient. As a result, it has become clinically desirable to augment mechanical fixation with biologic strategies in order to accelerate osteogenesis and promote successful arthrodesis. The discovery of bone morphogenic protein (BMP) has been pivotal in understanding the biology of fracture healing and has been a source of intense clinical research as an adjunct to fracture treatment. Multiple in vitro and in vivo studies in animals have elucidated the complex biologic interactions between BMPs and cellular receptors and have convincingly demonstrated rhBMP-2 to be a safe, effective treatment option to enhance bone healing. Multiple clinical trials in trauma surgery have provided level 1 evidence for the use of rhBMP-2 as a safe and effective treatment of fractures. Human clinical trials have provided further insight into BMP-2 dosage, time course, carriers, and efficacy in fracture healing of tibial defects. These promising results have provided hope that a new biologic field of technology has emerged as a useful adjunct in the treatment of skeletal injuries and conditions.Keywords: bone morphogenic protein-2, bone fracture, bone healing