Sergio Mendoza-Lattes

University of Iowa, Iowa City, IA, United States

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Publications (11)16.31 Total impact

  • Christopher T Martin, Andrew J Pugely, Yubo Gao, Sergio Mendoza-Lattes
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    ABSTRACT: Risk factors for complication after single-level anterior cervical discectomy and fusion remain poorly defined. The purpose of this study was to identify the incidence and risk factors for complication from a large, prospectively collected database, with a separate emphasis on the safety of outpatient procedures.
    The Journal of bone and joint surgery. American volume. 08/2014; 96(15):1288-1294.
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    ABSTRACT: Study Design. Retrospective Cohort StudyObjective. To determine the trends and causes for increases in hospital charges in adolescent idiopathic scoliosis (AIS) fusions.Summary of Background Data. Trends in utilization rates, surgical procedure types, and hospital charges for AIS fusions have not been well investigated.Methods. We used ICD-9 billing codes to identify 29,594 AIS fusion cases from the National Inpatient Service (NIS) database between 2001 and 2011. Data was trended over time, and contrasted against other common procedures. In order to identify specific drivers of charges, we queried our own hospital's billing system, and averaged charges from 40 cases (10 cases for each of four years studied). Dollar amounts were adjusted for inflation to 2011 dollars.Results. Utilization rates for AIS fusions have remained constant, whereas utilization of adult spinal fusions increased 64%% (p = 0.0004). Utilization of anterior thoracic fusions decreased 80% (p<0.0001). Mean hospital charges for AIS spinal fusions increased from $72,780 in 2001 to $155,278 in 2011 (113% increase), averaging 11.3% annually (p<0.0001), with charges for adult spinal procedures increasing at a similar rate (13.4% annually, p<0.0001). Charges for the other non-spine conditions increased to a lesser degree (range of 4.5%-6% annually, p<0.001 for each). At our institution, spinal implant charges increased 27.6% annually, while surgeon charges decreased 0.5% annually, and all other charges increased only 5.2% annually. Over time, our surgeon used greater numbers of pedicle screws, and greater numbers of implants per surgery and per level fused (p<0.05 for each). Implant charges were 28% of the total hospital bill in 2003, rising to 53% in 2012.Conclusions. While utilization rates for AIS fusions have remained constant over time, hospital charges have increased substantively, and there has been a shift towards performing posterior only surgeries. This corresponds to the widespread adoption of pedicle screw based constructs. Spinal implants may be the primary driver of increased charges. Strategies directed towards implant cost-savings may thus have the largest impact.
    Spine 06/2014; · 2.16 Impact Factor
  • Andrew J Pugely, Christopher T Martin, Yubo Gao, Sergio Mendoza-Lattes
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    ABSTRACT: Study Design. Retrospective review of a prospective cohortObjective. To determine the incidence, causes, and risk factors for 30-day unplanned readmissions after lumbar spine surgery.Summary of Background Data. The rising costs associated with lumbar spinal surgery have received national attention. Recently, the government has chosen to target 30-day readmissions as a quality measure. Few studies have specifically analyzed the incidence, causes, and risk factors for readmission in a multi-center patient cohort.Methods. A large, multi-center clinical registry was queried for all patients undergoing lumbar spine surgery in 2012. CPT codes were used to select patients undergoing lumbar discectomy, laminectomy, anterior and posterior fusions, and multi-level deformity surgery. Thirty-day readmissions rates and causes were identified and analyzed. Univariate and multivariate logistic regression analysis was used to identify patient characteristics, comorbidities, and operative variables predictive of readmission.Results. Overall, 695 of 15,668 patients undergoing lumbar spine had unplanned 30-day hospital readmissions (4.4%). When separated by procedure type, readmissions were lowest after discectomy, 3.3%, and highest after deformity surgery, 9.0% (p < 0.001). The top causes for readmission were wound-related (38.6%), pain-related (22.4%), thromboembolic (9.4%), and systemic infections (8.0%). Predictors of readmission included advanced patient age > 80 years (p = 0.03), Black race (p = 0.03), recent weight loss (p = 0.04), COPD (p < 0.01), history of cancer (p = 0.04), creatinine > 1.2 (p < 0.01), elevated ASA Class (p = 0.01), operative time > 4 hours (p = 0.01), and prolonged hospital length of stay > 4 days (p < 0.01).Conclusion. Thirty-Day unplanned readmission rates increased with procedure invasiveness. Both medical and surgical reasons contributed to readmission, many unavoidable. Surgeons should explore optimization measures for those at risk of early, unplanned readmission.
    Spine 02/2014; · 2.16 Impact Factor
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    ABSTRACT: Retrospective cohort study. To demonstrate a correlation between radiculopathy symptoms, foraminal morphology, and curve types. Patients with degenerative scoliosis frequently present with foraminal stenosis and radiculopathy, the origin of which is not well understood. 48 patients (384 foraminas)-16 femoral nerve pain (F) and 18 sciatic nerve pain (S). The symptomatic foramen of Group F and Group S were compared to asymptomatic foramina. Alignment was measured from standardized radiographs; 3D CT-reconstructions were used to measure foraminal height and area. Data is presented as mean±SD. Chi-square, T-test and Pearson's coefficients were calculated; Inter-, intra-observer reproducibility (Cohen's kappa). 17/18 patients with sciatic nerve pain (S) presented foraminal stenosis (<40 mm) at the concavity of the fractional curve distal to the main lumbar structural curve. The symptomatic foramina were significantly smaller in height (7.8±2.5 mm vs. 12.1±3.1 mm, P<0.0001) and area (30.1±14.3 mm² vs. 57.6±28.7 mm², P<0.0001) compared to asymptomatic foramen; 7/7 patients with femoral nerve pain (F) and lumbar structural curves (apex L3 or lower) had foraminal stenosis at the concavity of the fractional curve. In 8/9 patients with femoral nerve pain (F) and thoracic, thoraco-lumbar, or lumbar (apex L2 or higher) curves, presented foraminal stenosis in the concavity of the caudal fractional curve. The symptomatic foraminal spaces were significantly smaller in height (9.2±3.2 mm vs. 12.1±3.1 mm, P<0.0001) and area (30.1±15.2 mm² vs. 57.6±28.7 mm², P<0.0001). Foraminal height correlated with foraminal area (r=0.68-0.85; P<0.0001). Inter-observer agreement was between 0.6092-0.8679. A correlation between curve types and symptomatic foraminal stenosis exists. Adult scoliosis patients with sciatic nerve pain typically present with foraminal stenosis at the concavity of the caudal fractional curve. Similarly, patients with femoral nerve pain present with foraminal stenosis at the concavity of the caudal fractional curve when the main structural curve is thoracic, thoraco-lumbar or lumbar (apex L2 or higher).
    Journal of spinal disorders & techniques 09/2013; · 1.21 Impact Factor
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    ABSTRACT: BACKGROUND: Spinal anesthesia has been associated with lower postoperative rates of deep-vein thrombosis, a shorter operative time, and less blood loss when compared with general anesthesia. The purpose of the present study was to identify differences in thirty-day perioperative morbidity and mortality between anesthesia choices among patients undergoing total knee arthroplasty. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was searched to identify patients who underwent primary total knee arthroplasty between 2005 and 2010. Complications that occurred within thirty days after the procedure in patients who had been managed with either general or spinal anesthesia were identified. Patient characteristics, thirty-day complication rates, and mortality were compared. Multivariate logistic regression identified predictors of thirty-day morbidity, and stratified propensity scores were used to adjust for selection bias. RESULTS: The database search identified 14,052 cases of primary total knee arthroplasty; 6030 (42.9%) were performed with the patient under spinal anesthesia and 8022 (57.1%) were performed with the patient under general anesthesia. The spinal anesthesia group had a lower unadjusted frequency of superficial wound infections (0.68% versus 0.92%; p = 0.0003), blood transfusions (5.02% versus 6.07%; p = 0.0086), and overall complications (10.72% versus 12.34%; p = 0.0032). The length of surgery (ninety-six versus 100 minutes; p < 0.0001) and the length of hospital stay (3.45 versus 3.77 days; p < 0.0001) were shorter in the spinal anesthesia group. After adjustment for potential confounders, the overall likelihood of complications was significantly higher in association with general anesthesia (odds ratio, 1.129; 95% confidence interval, 1.004 to 1.269). Patients with the highest number of preoperative comorbidities, as defined by propensity score-matched quintiles, demonstrated a significant difference between the groups with regard to the short-term complication rate (11.63% versus 15.28%; p = 0.0152). Age, female sex, black race, elevated creatinine, American Society of Anesthesiologists class, operative time, and anesthetic choice were all independent risk factors of short-term complication after total knee arthroplasty. CONCLUSIONS: Patients undergoing total knee arthroplasty who were managed with general anesthesia had a small but significant increase in the risk of complications as compared with patients who were managed with spinal anesthesia; the difference was greatest for patients with multiple comorbidities. Surgeons who perform knee arthroplasty may consider spinal anesthesia for patients with comorbidities. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
    The Journal of Bone and Joint Surgery 12/2012; · 3.23 Impact Factor
  • Andrew J Pugely, Christopher T Martin, Yubo Gao, Sergio A Mendoza-Lattes
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    ABSTRACT: Study Design. Propensity score adjusted prospective cohort study.Objective. To compare the incidence of complications in patients undergoing single level lumbar discectomy between the inpatient and outpatient settings, to determine baseline 30-day complication rates for lumbar discectomy, and to identify independent risk factors for complications.Summary of Background Data. Lumbar discectomy is the most common spinal procedure performed, and can be done on an outpatient basis. Lower costs, greater patient satisfaction, and equivalent safety have been reported with outpatient surgery.Methods. Patients undergoing lumbar discectomy between 2005 and 2010 were selected from The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. Patient selection was based on a single primary CPT code. In order to ensure comparable inpatient and outpatient cohorts, patients with multi-level procedures were excluded. Thirty-day post-operative complications and pre-operative patient characteristics were identified and compared. Propensity score matching and multivariate logistic regression analysis were used to adjust for selection bias and identify predictors of 30-day morbidity.Results. Of the 4,310 lumbar discectomy cases, 2,658 (61.7%) underwent an inpatient hospital stay following surgery, while 1,652 (38.3%) patients had outpatient surgery. Unadjusted overall complication rates (6.5% vs 3.5%, p < 0. 0001) were higher in those undergoing inpatient surgery. After propensity score matching, overall complication rate was still higher with the inpatient cohort (5.4% vs 3.5%, p = 0.0068). Adjusted comparison using multivariate logistic regression, also demonstrated a significantly higher rate of complication for inpatients (OR1.521; 95% CI 1.048-2.206). Age, diabetes, presence of pre-operative wound infection, blood transfusion, operative time, and an inpatient hospital stay were all independent risk factors of short term complication after lumbar discectomy.Conclusions. After adjusting for confounders using propensity score matching and multivariate logistic regression analysis, patients undergoing outpatient lumbar discectomy had lower overall complication rates than those treated as inpatients. Surgeons should consider outpatient surgery for lumbar discectomy in appropriate candidates.
    Spine 07/2012; · 2.16 Impact Factor
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    Sergio Mendoza-Lattes, Zachary Ries, Yubo Gao, Stuart L Weinstein
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    ABSTRACT: PROXIMAL JUNCTIONAL KYPHOSIS (PJK) IS DEFINED AS: 1) Proximal junction sagittal Cobb angle >≥10°, and 2) Proximal junction sagittal Cobb angle of at least 10° greater than the pre-operative measurement PJK is a common complication which develops in 39% of adults following surgery for spinal deformity. The pathogenesis, risk factors and prevention of this complication are unclear. Of 54 consecutive adults treated with spinal deformity surgery (age≥59.3±10.1 years), 19 of 54 (35%) developed PJK. The average follow-up was 26.8 months (range 12 - 42). Radiographic parameters were measured at the pre-operative, early postoperative (4-6 weeks), and final follow-up visits. Sagittal alignment was measured by the ratio between the C7-plumbline and the sacral-femoral distance. Binary logistic regression model with predictor variables included: Age, BMI, C7-plumbline, and whether lumbar lordosis, thoracic kyphosis and sacral slope were present Patients who developed PJK and those without PJK presented with comparable age, BMI, pelvic incidence and sagittal imbalance before surgery. They also presented with comparable sacral slope and lumbar lordosis. The average magnitude of thoracic kyphosis was significantly larger than the lumbar lordosis in the proximal junctional kyphosis group, both at baseline and in the early postoperative period, as represented by [(-lumbar )lordosis - (thoracic kyphosis)]; no- PJK versus PJK; 6.6°±23.2° versus -6.6°±14.2°; p≥0.012. This was not effectively addressed with surgery in the PJK group [(-LL-TK): 6.2°±13.1° vs. -5.2°±9.6°; p≥0.004]. This group also presented with signs of pelvic retroversion with a sacral slope of 29.3°±8.2° pre-operatively that was unchanged after surgery (30.4°±8.5° postoperatively). Logistic regression determined that the magnitude of thoracic kyphosis and sagittal balance (C7-plumbline) was the most important predictor of proximal junctional kyphosis. Proximal junctional kyphosis developed in those patients where the thoracic kyphosis remained greater in magnitude relative to the lumbar lordosis, and where the sagittal balance seemed corrected, but part of thise correction was secondary to pelvic retroversion. Prognostic case-control study - Level III.
    The Iowa orthopaedic journal 01/2011; 31:199-206.
  • Sergio Mendoza-Lattes, Zachary Ries, Yubo Gao, Stuart L Weinstein
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    ABSTRACT: Cross-sectional study and systematic review of the literature. Describe the natural history of spinopelvic alignment parameters and their behavior in patients with degenerative spinal deformity. Normal stance and gait requires congruence between the spine-sacrum and pelvis-lower extremities. This is determined by the pelvic incidence (PI), and 2 positional parameters, the pelvic tilt, and sacral slope (SS). The PI also affects lumbar lordosis (LL), a positional parameter. The final goal is to position the body's axis of gravity to minimize muscle activity and energy consumption. Two study cohorts were recruited: 32 healthy teenagers (Risser IV-V) and 54 adult patients with symptomatic spinal deformity. Standing radiographs were used to measure spinopelvic alignment and positional parameters (SS, PI, sacral-femoral distance [SFD], C7-plumbline [C7P], LL, and thoracic kyphosis). Data from comparable groups of asymptomatic individuals were obtained from the literature. PI increases linearly with age (r2 = 0.8646) and is paralleled by increasing SFD (r2 = 0.8531) but not by SS. Patients with symptomatic deformity have higher SFD (42 +/- 13.6 mm vs. 63.6 +/- 21.6 mm; P < 0.001) and lower SS (42 degrees +/- 9.6 degrees vs. 30.7 degrees +/- 13.6 degrees; P < 0.001) but unchanged PI. The C7P also presents a linear increase throughout life (r2 = 0.8931), and is significantly increased in patients with symptomatic deformity (40 +/- 37 mm vs. 70.3 +/- 59.5 mm; P < 0.001). First, Gradual increase in PI is described throughout the lifespan that is paralleled by an increase in SFD, and is not by an increase in the SS. This represents a morphologic change of the pelvis. Second, Patients with symptomatic deformity of the spine present an increased C7P, thoracic hypokyphosis, reduced LL, and signs of pelvic retroversion (decreased LL and SS; increased SFD).
    Spine 07/2010; 35(16):E792-8. · 2.16 Impact Factor
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    ABSTRACT: Retrospective case-control study. To compare the effectiveness between caudal and trans-foraminal epidural steroid injections for the treatment of primary lumbar radiculopathy. Spinal injections with steroids play an important role in non-operative care of lumbar radiculopathy. The trans-foraminal epidural steroid injection (TESI) theoretically has a higher success rate based on targeted delivery to the symptomatic nerve root. To our knowledge, these results have not been compared with other techniques of epidural steroid injection. 93 patients diagnosed with primary lumbar radiculopathy of L4, L5, or SI were recruited for this study: 39 received caudal epidural steroid injections (ESI) and 54 received trans-foraminal epidural steroid injections (TESI). Outcomes scores included the SF-36, Oswestry disability index (ODI) and pain visual analogue scale (VAS), and were recorded at baseline, post-treatment (<6 months), long-term (>1 year). The average follow-up was 2 years, and 16 patients were lost to follow-up. The endpoint "surgical intervention" was a patient-driven decision, and considered failure of treatment. Intent-to-treat analysis, and comparisons included t-test, Chi-square, and Wilcoxon rank-sum test. Baseline demographics and outcomes scores were comparable for both treatment groups (ESI vs. TESI): (SF-36 PCS (32.3 +/- 7.5 vs. 29.5 +/- 8.9 respectively; p = 0.173), MCS (41.2 +/- 12.7 vs. 41.1 +/- 10.9, respectively; p = 0.971), and VAS (7.4 +/-2.1 vs. 7.9 +/- 1.2, respectively; p = 0.228)). Surgery was indicated for failure of treatment at a similar rate for both groups (41.0% vs. 44.4%, p=0.743). Symptom improvement was comparable between both treatment groups (ESI vs. TESI): SF-36 PCS improved to 42.0+/-11.8 and 37.7+/-12.3, respectively; p=0.49; ODI improved from 50.0+/-21.2 to 15.6+/-17.9and from 62.1+/-17.9 to 26.1+/-20.3, respectively (p=0.407). The effectiveness of TESI is comparable to that of ESI (approximately 60%) for the treatment of primary lumbar radiculopathy. The increased complexity of TESI is not justified for primary cases, and may have a more specific role in recurrent disease or for diagnostic purposes.
    The Iowa orthopaedic journal 01/2009; 29:91-6.
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    ABSTRACT: The prevalence of dysphagia after anterior cervical decompression and arthrodesis is estimated to be 50% within one month and 21% at twelve months. However, its exact etiology is not well understood. The objective of the present study was to explore the relationship between intraoperative intra-esophageal pressure due to surgical retraction, esophageal mucosal blood flow at the level of surgery, and postoperative dysphagia. Our hypothesis was that sustained elevated pressure on the esophagus during anterior cervical arthrodesis is associated with postoperative dysphagia. Seventeen selected patients scheduled for anterior cervical arthrodesis were studied. Throughout the procedure, intraluminal pressure in the upper esophageal sphincter was measured (mm Hg) with a custom-made manometer probe and mucosal perfusion was measured at the level of surgery with a laser Doppler flowmeter. The type of retraction chosen by the surgeon was noted. Postoperatively, the patients were specifically evaluated for dysphagia on the first postoperative day and at six weeks, three months, and six months postoperatively with use of the M.D. Anderson Dysphagia Inventory. Four of the eleven patients who had dynamic retraction and five of the six patients who had static retraction during surgery had postoperative dysphagia. In the group of patients with dysphagia, the average M.D. Anderson Dysphagia Inventory score decreased from 93.8 +/- 12.1 preoperatively to 67.7 +/- 11.4 on the first postoperative day (p < 0.001). The patients with dysphagia had a significantly higher average intraluminal pressure (60.8 +/- 54.3 compared with 54.4 +/- 51.8 mm Hg; p < 0.0001) as well as significantly lower average mucosal perfusion (26.1 +/- 18.1 compared with 40.8 +/- 26.2 tissue perfusion units; p < 0.0001) in comparison with the asymptomatic patients. Patients with dysphagia following anterior cervical arthrodesis were exposed to higher intraoperative esophageal pressure and decreased esophageal mucosal blood flow during surgical retraction as compared with patients without dysphagia. In this small series, dynamic retraction seemed to be associated with a lower prevalence of postoperative dysphagia.
    The Journal of Bone and Joint Surgery 02/2008; 90(2):256-63. · 3.23 Impact Factor
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    ABSTRACT: The case of a four-year-old child is described who presented to our institution with cervicothoracic deformity and a two-year history of progressive paraparesis. His past medical history was significant for meningocele which was closed at age two months. Imaging studies revealed severe congenital kyphosis with a hypoplastic T3 vertebra, as well as a tethered filum terminale with a conus lipoma. The spinal cord was found to be severely compressed at the apex of the kyphotic deformity. Discussion is focused on the diagnosis of tethered cord syndrome, and treatment options. In particular, this case required careful thought on the order of events, which followed initial tethered cord release and removal of the conus lipoma, and subsequent kyphectomy and fusion of the upper thoracic spine. A favorable clinical outcome was obtained with complete reversal of the paraparesis.
    The Iowa orthopaedic journal 02/2007; 27:85-9.

Publication Stats

62 Citations
16.31 Total Impact Points


  • 2008–2013
    • University of Iowa
      • Department of Orthopaedics and Rehabilitation
      Iowa City, IA, United States
  • 2007
    • Hospital Pequeno Príncipe
      Curityba, Paraná, Brazil