Early Outcomes of Primary Total Hip Arthroplasty After Prior Lumbar Spinal Fusion

The Journal of Arthroplasty xxx (2016) 1e5

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Original Article

Early Outcomes of Primary Total Hip Arthroplasty After Prior Lumbar Spinal Fusion Jeffrey J. Barry, MD, David C. Sing, BS, Thomas P. Vail, MD, Erik N. Hansen, MD * Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California

a r t i c l e i n f o

a b s t r a c t

Article history: Received 20 January 2016 Received in revised form 3 July 2016 Accepted 14 July 2016 Available online xxx

Background: The coexistence of degenerative hip disease and spinal pathology is not uncommon with the number of surgical treatments performed for each condition increasing annually. The limited research available suggests spinal pathology portends less pain relief and worse outcomes after total hip arthroplasty (THA). We hypothesize that primary THA patients with preexisting lumbar spinal fusions (LSF) experience worse early postoperative outcomes. Methods: This study is a retrospective matched cohort study. Primary THA patients at 1 institution who had undergone prior LSF (spine arthrodesis-hip arthroplasty [SAHA]) were identified and matched to controls of primary THA without LSF. Early outcomes (<90 days) were compared. Results: From 2012 to 2014, 35 SAHA patients were compared to 70 matched controls. Patients were similar in age, sex, American Society of Anesthesiologist score, body mass index, and Charlson Comorbidity Index. SAHA patients had higher rates of complications (31.4% vs 8.6%, P ¼ .008), reoperation (14.3% vs 2.9%, P ¼ .040), and general anesthesia (54.3% vs 5.7%, P ¼ .0001). Bivariate analysis demonstrated SAHA to predict reoperation (odds ratio, 5.67; P ¼ .045) and complications (odds ratio, 4.89; P ¼ .005). With the numbers available, dislocations (0% vs 2.8%), infections (0% vs 8.6%), readmissions, postoperative walking distance, and disposition only trended to favor controls (P > .05). Comparing controls to SAHA patients with <3 or 3 levels fused, longer fusions had increased cumulative postoperative narcotic consumption (mean morphine equivalents, 44.3 vs 46.9 vs 169.4; P ¼ .001). Conclusion: Patients with preexisting LSF experience worse early outcomes after primary THA including higher rates of complications and reoperation. Lower rates of neuraxial anesthesia and increased narcotic usage represent potential contributors. The complex interplay between the lumbar spine and hip warrants attention and further investigation. © 2016 Elsevier Inc. All rights reserved.

Keywords: total hip arthroplasty lumbar spinal fusion hip-spine syndrome arthroplasty outcomes arthroplasty complications postoperative narcotic usage

Disorders of the adult hip and spine are common, and treatment for the various pathologies represents a significant portion of health-care burden in the United States. Total hip arthroplasty (THA) and lumbar spinal fusion (LSF) are 2 of the more common and effective procedures performed for the treatment of advanced degenerative pathology of the hip and spine. The number of THAs

One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2016.07.019. * Reprint requests: Erik N. Hansen, MD, Department of Orthopaedic Surgery, University of California, San Francisco, 500 Parnassus Ave, MU320W, San Francisco, CA 94143. http://dx.doi.org/10.1016/j.arth.2016.07.019 0883-5403/© 2016 Elsevier Inc. All rights reserved.

performed in 2010 exceeded 300,000 with a projected rise to over 500,000 by the year 2020 [1]. Meanwhile, low back pain has been reported to affect 73% of the population and 413,000 spinal fusions were performed in 2008 (a 137% increase from 1998) [2,3]. There is evidence that degenerative hip disorders often coexist and parallel degenerative changes of the lumbar spine [4,5]. This combination of spinal stenosis and hip arthritis was coined “hip-spine syndrome” by Offierski and MacNab [6]. Despite the prevalence of pathologies of the hip and spine, little has been published regarding the interplay of these 2 common conditions. The limited research to date suggests patients with spinal pathology experience less pain relief and worse outcomes after THA compared to THA patients without spinal disorders [7-10]. Parvizi et al and Staibano et al demonstrated worse patient-reported outcomes in patients who had preexisting back pain after

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primary THA via HHS, SF-36 physical and mental scores, and Oxford Hip Scores [7,9]. Similarly, Prather et al [8] found that patients with lumbar spine disorders had less pain relief after THA and experienced less improvement in activity levels and function, compared with patients with THA alone based on modified Harris Hip Score and University of California, Los Angeles activity score. They also found increase in expenditures per episode of care and increased length of each care episode for the same cohort. LSF is often employed as part of the treatment for numerous spinal pathologies including spinal stenosis, spondylolisthesis, and sagittal or coronal deformity. LSF reduces flexibility, can alter spinopelvic parameters and sagittal balance, and subsequently changes the joint mechanics of the hip. Additionally, these patients often have more functional limitations and are more likely to be on chronic pain medications. Furthermore, the presence of a prior lumbar fusion mass may make neuraxial anesthesia difficult if not impossible to accomplish, relegating the patient to general anesthesia and postoperative intravenous and oral opiates with their attendant side effects. All of these variables may adversely affect the success of a primary THA in the immediate postoperative period. There is currently a dearth of published literature regarding outcomes of primary THA in patients with preexisting LSF. For this reason, we undertook the following investigation. We hypothesize that primary THA patients who have previously undergone LSF experience worse early postoperative outcomes, including worse pain scores, higher opiate requirement, as well as a higher complication and reoperation rate. Methods A retrospective case-control study was performed sampling patients from June 2012 to January 2015 at a single tertiary care center, academic institution. The start date was chosen based on the date of implementation of the institution's current electronic medical record which allowed queries of many of the variables of interest. All primary THA patients at our institution who had undergone prior LSF, deemed spine arthrodesis-hip arthroplasty (SAHA), were identified via chart review. Spine fusions (instrumented and uninstrumented) were identified by patient-reported surgical history, operative notes if the surgery was performed at the same institution, or radiographs identifying spinal fusion instrumentation. These patients were further categorized based on the length of fusion for subgroup analysis as 3 levels or 1-2 levels. SAHA patients were then matched (1:2) using propensity scoring based on age, sex, and American Society of Anesthesiologist (ASA) score to a control group of primary THA patient who had not undergone a prior LSF. Patients were not excluded from the control group if they had other prior spine diagnoses, nonfusion operations, or back pain. Fusions that did not include the lumbar spine were not included in the SAHA group (ie, Anterior Corpectomy Discectomy Fusion patients). Patients were excluded if joint arthroplasty was performed for acute fractures or oncologic diagnoses. The standard arthroplasty protocol at our institution was employed for all patients within the cohort. The preferred anesthetic modality was a single-shot spinal. Patients were treated postoperatively with a multimodal pain control pathway that included nonsteroidal anti-inflammatory drugs, acetaminophen, and breakthrough oral and intravenous narcotics for pain. Deep venous thrombosis prophylaxis included mechanical prophylaxis immediately postoperatively as well as subcuticular lowmolecular-weight heparin injections initiated on the morning of postoperative day 1 (POD1). Antibiotic prophylaxis was continued for 24 hours postoperatively. Exceptions were made when medically indicated. In regard to intraoperative anesthesia, reasons for deviation from a single-shot spinal included patient preference,

Table 1 Cohort Characteristics. Patient Characteristics

Control

SAHA

Total Age (y), mean (SD) Sex Female Male ASA rating 2 3 Anesthesia type Single-shot spinal General Epidural CCI 0 1 2 >3 BMI Underweight (<18.5) Normal (18.5-24) Overweight (25-29) Obese class I (30-34) Obese class II (35-40) Obese class III (>40) Preoperative opioid use Nonuser Opioid user Spinal levels fuseda No prior fusion 1-2 Levels 3 Levels Fusion includes S1/pelvis Surgical approach Anterolateral Posterior Direct anterior

70 68.4 (10.6)

35 68.5 (9.2)

39 (55.7%) 31 (44.3%)

21 (60.0%) 14 (40.0%)

39 (55.7%) 31 (44.3%)

19 (54.3%) 16 (45.7%)

66 (94.3%) 4 (5.7%) 0 (0%)

15 (42.9%) 19 (54.3%) 1 (2.9%)

47 12 6 5

(67.1%) (17.1%) (8.6%) (7.1%)

24 7 3 1

(68.6%) (20%) (8.6%) (2.9%)

1 18 28 15 4 4

(1.4%) (25.7%) (40%) (21.4%) (5.7%) (5.7%)

0 13 6 9 3 4

(0%) (37.1%) (17.1%) (25.7%) (8.6%) (11.4%)

P Value .995 .728

1

<.001

.807

.144

.007 42 (60%) 28 (40%)

11 (31.4%) 24 (68.8%)

70 0 0 0

0 17 17 24

<.001 (100%) (0%) (0%) (0%)

(0%) (50.0%) (50.0%) (70.6%) .204

43 (61.4%) 21 (30.0%) 6 (8.6%)

18 (51.4%) 16 (45.7%) 1 (2.9%)

SAHA, spine arthrodesis-hip arthroplasty; SD, standard deviation; ASA, American Society of Anesthesiologist; CCI, Charlson Comorbidity Index; BMI, body mass index. a One patient with unknown fusion length excluded from subgroup analysis.

anesthesia team preference, failure of neuraxial anesthesia, and inability to place a needle through the spinal fusion mass. Demographic, claims, and early postoperative outcome data were collected via chart review from the electronic medical record retrospectively. Demographic data collected included age, gender, and body mass index (BMI). Patient administrative records were reviewed to calculate Charlson Comorbidity Index (CCI) without age adjustment using 16 comorbidities identified through International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9_CM) coding [11]. Data collected included type of anesthesia, pain scores using the visual analog scale (VAS), and opiate usage (calculated as morphine equivalent/day). Walking distance with physical therapy (recorded in maximum distance ambulated/therapy session) was used as a proxy for mobility. Disposition following hospital discharge was recorded as either home or facility (skilled nursing facility or acute rehabilitation facility). Complications (both operative and nonoperative) were recorded by direct chart review of all available records, as were any readmissions or reoperations that occurred within 90 days of the THA surgery. Cases were compared to controls on the above variables and statistical significance defined as P < .05. Chi-square or Fisher exact tests were used to compare categorical data based on sample size. Student t test or analysis of variance was used when comparing the groups of distributed data. Bivariate analysis was performed to identify association of predictor variables on outcomes of interest including reoperation, complication, and disposition. Findings were

J.J. Barry et al. / The Journal of Arthroplasty xxx (2016) 1e5 Table 2 Pain and Narcotic Use. Control

SAHA < 3 Level Fusion

SAHA  3 Levels Fusion

Total 70 17 17 Average VAS, mean (SD) Preop 3.2 (3.2) 4.1 (3.5) 4.7 (3.9) POD0 1.2 (1.4) 2.9 (2.4) 4.2 (2.6) POD1 2.8 (1.9) 3.2 (1.6) 3.7 (2.2) POD2 2.7 (1.9) 2.4 (1.6) 3.4 (2.4) POD3 2.7 (1.9) 2.8 (2.4) 3.3 (2.5) Average morphine equivalents consumed, mean (SD) Total 44.3 (55.2) 46.9 (33.1) 169.4 (284) POD0 7.4 (13.1) 15.5 (16.7) 41.8 (68) POD1 16.6 (21.4) 17.1 (13.5) 54.4 (80.9) POD2 12 (16.7) 10.3 (11.7) 34.3 (56.1) POD3 4.5 (10) 3.1 (5.7) 28.8 (95.1)

P Value

.280 <.001 .190 .324 .790 .001 <.001 .001 .008 .062

SAHA, spine arthrodesis-hip arthroplasty; VAS, visual analog scale; preop, preoperatively; POD, postoperative day; SD, standard deviation.

reported as odds ratios (OR) with 95% confidence intervals and P value. All analyses were performed using R version 3.0.2 (R Project). Results From June 2012 through January 2015, 35 SAHA patients were identified of 725 total primary THA (4.8%). Patients were matched to 70 controls based on age, sex, and ASA score. Patients were similar in BMI, CCI, and surgical approach employed (P > .05; Table 1). Three fellowship-trained joint arthroplasty surgeons (including 2 Hip Society members) at a tertiary care center performed all cases included in the analysis except for 4 (2 cases in each group). The average age of patients was 68.4 years with a predominance of women in both groups (55.7% controls, 60% SAHA). In regard to the type of anesthesia administered at the time of the primary THA, 94.3% of controls received a single-shot spinal compared to 42.9% of SAHA patients (P < .001). Cited reasons for abandonment of neuraxial anesthesia included patient preference, anesthesia team preference, failure of neuraxial anesthesia, and inability to place a needle through the spinal fusion mass. Opioid use was significantly higher preoperatively in SAHA patients (40% controls vs 68% SAHA; P ¼ .007). Of the patients using opioids preoperatively, none of the controls (0 of 28 patients) used longacting opioid formulations compared to 20.8% of SAHA opioid users (5 of 24 patients). For the subgroup analysis, 17 of 35 patients had a fusion spanning 3 or more levels and 17 of 35 had 1-2 levels

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fused. One patient had instrumentation visible on plain films but the length was not able to be determined so they were included in SAHA vs control analysis but excluded for subgroup analysis. Average early postoperative pain scores and total pain medication usage were higher for SAHA patients compared to control primary THA patients (Table 2). After performing subgroup analysis breaking the SAHA patients into short (1-2 levels) and long (3 levels) constructs, it became evident that longer spine fusion patients accounted for the majority of the difference seen. Longer spine fusion constructs resulted in higher early VAS pain scores on POD0 (control ¼ 1.2 vs SAHA [1-2 levels] ¼ 2.9 vs SAHA [3 levels] ¼ 4.2, P < .001) and increased postoperative narcotic consumption (total cumulative mean morphine equivalents THA ¼ 44.3 vs SAHA<3 ¼ 46.9 vs SAHA3þ ¼ 169.4, P ¼ .001; Fig. 1). The increased narcotic usage trended for all days of stay, not just POD0 and POD1, which might have been predicted as a result of decreased rates of spinal analgesia. Length of stay (2.9 vs 2.7 days, P ¼ .313), disposition (22.9% vs 31.4% placement, P ¼ .477), and distance walked by POD1 (133.7 vs 114 ft, P ¼ .548) did not differ significantly between controls and SAHA patients, respectively (Table 3). There were significantly more patients who experienced a complication (8.6% controls vs 34.3% SAHA, P ¼ .008) or reoperation (2.9% controls vs 14.3% SAHA, P ¼ .040) within the early postoperative period in patients with preexisting LSF at the time of primary THA (Table 3). Readmission rates trended to favor controls (4.3% control vs 17.1% SAHA, P ¼ .057). Three of the prior LSF group had a periprosthetic joint infection (8.6%) within the first 90 days requiring reoperation compared to none of the controls (Table 4). Other complications seen in the SAHA group and not seen in the control group included prosthetic dislocation treated with closed reduction and bracing (2.9%), prolonged delirium >2 days (5.7%), a fall with a severe compression fracture of the spine requiring readmission (2.9%), and a C. difficile infection in a patient discharged to a skilled nursing facility (2.9%). There were no significant differences found in the complication or reoperation rates with subgroup analysis comparing the short vs long fusion constructs. Bivariate analysis demonstrated prior LSF to predict reoperation (OR, 5.67; P ¼ .045) and complications (OR, 4.89; P ¼ .005; Table 5). General anesthesia was also a predictor of reoperation (OR, 5.47; P ¼ .035) and complications (OR, 4.27; P ¼ .01). Interestingly BMI > 30 predicted complication (OR, 2.91; P ¼ .049); however, age, higher CCI, and ASA score did not predict complications or reoperations with the numbers available for study. In our small study, prior LSF did not predict discharge to facility; however, traditional measures of frailty including age > 75 (OR, 7.74; P ¼ .008), ASA score 3 (OR, 4.24; P ¼ .003), and CCI of 3 (OR, 8.14; P ¼ .022) were predictive of disposition to skilled nursing facility or rehabilitation center.

Table 3 Early Outcomes Following THA.

Total Distanced walked POD1, mean (SD) Length of stay, mean (SD) Disposition Home Placement (SNF/rehab) Complications (<90 days) Readmissions (<90 days) Reoperations (<90 days) Fig. 1. Average opioid consumption per patient converted to mean morphine equivalents by postoperative day for total hip arthroplasty patients without prior lumbar spinal fusion (control), with <3 levels fused or 3 levels fused.

Control

SAHA

70 133.7 (175) 2.9 (1)

35 114 (116.6) 2.7 (0.7)

54 16 6 3 2

(77.1%) (22.9%) (8.6%) (4.3%) (2.9%)

24 11 12 6 5

(68.6%) (31.4%) (34.3%) (17.1%) (14.3%)

P Value .548 .313 .477

.008 .057 .040

THA, total hip arthroplasty; SAHA, spine arthrodesis-hip arthroplasty; SNF, skilled nursing facility; rehab, rehabilitation facility; POD, postoperative day; SD, standard deviation.

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Table 4 Postoperative Complications Within 90 Days.

Patients with complications Total complications Nonoperative complications Superficial wound infection Pneumonia ICU transfer Prolonged delirium Prosthetic dislocation Fall and non-periprosthetic fracture C. difficile infection Complication requiring reoperation Mechanical loosening Periprosthetic fracture Periprosthetic joint infection Hardware complication

Control (N ¼ 70)

SAHA (N ¼ 35)

P Value

6 (8.6%) 6 4 (5.7%) 2 1 1 0 0 0

12 (34.3%) 13 7 (20%) 1 1 1 2 1 1

.008

0 2 (2.9%)

1 5 (14.3%)

1 1 0 0

.039

.039

0 1 3 1

SAHA, spine arthrodesis-hip arthroplasty; ICU, intensive care unit.

Discussion This study represents the first of its kind to analyze outcomes after primary THA for patients who have operative spinal disorders treated with a prior LSF. Patients with prior LSF experienced worse early postoperative outcomes after primary THA than patients without a spinal arthrodesis including higher rates of complications and reoperations within 90 days. In addition, prior LSF patients required more opioid pain medication and had higher pain scores immediately postoperatively, an effect that was amplified by fusion lengths of 3 or more levels. Significant low back pain in preoperative THA candidates affects 21%-50% of patients, and 18%-25% of primary THA patients have either seen a spine specialist or carry a primary spinal diagnosis [79,12]. Bohl and Steffee [13] were the first to describe coexisting spine and hip disease when they reported on a cohort of patients who experienced pain relief from lumbar decompression after a THA had failed to completely resolve their symptoms. They and others have attempted to describe the complex interrelation between hip and low back pathology [6,8,10,14-16]. Our study expands on prior work by demonstrating prior operative lumbar spine pathology incurs a risk of worse early postoperative outcomes after primary THA. One of the most pronounced differences uncovered was the increased use of postoperative opioid medications within the SAHA group. The SAHA group had a significantly higher rate of preoperative

opioid usage compared to controls, and additionally 20.8% of the opioid users were taking long-acting opioid formulations. This certainly contributed to the higher postoperative opioid requirements used but other factors may have included decreased rates of neuraxial anesthesia and exacerbations of back pain in the acute postoperative setting (a described phenomenon even in patients without spinal disorders) [9,15]. Increased narcotic usage has been associated with a number of adverse outcomes including risks of fall, fracture, pneumonia, overdose, hyperalgesia, and delirium [1720]. Chronic opioid use before orthopedic surgeries including total knee arthroplasty and total shoulder arthroplasty has been associated with higher morbidity and mortality and poorer functional outcomes [20-22]. Many of the complications seen in the SAHA group could possibly be attributed to the higher rates of narcotic medication usage postoperatively (pneumonia, delirium, fractures). To evaluate functional status, SAHA patients were compared to controls by length of stay, distance walked with physical therapy on POD1, and location of disposition. With the limited numbers in our study, we found no difference between these variables. Distanced walked trended to decrease in the SAHA group but immobility from increased pain and narcotic usage in the prior fusion group may be seen with a larger study. Using available retrospective data of furthest distance ambulated as reported by physical therapy is limited in not completely capturing patient mobility which would be better served with a different study design. An interesting finding from this study was the high rates of general anesthesia and its associated correlation with higher complication and reoperation rates; 5.7% of controls compared to 54.7% of the SAHA group required general anesthesia. The benefits of neuraxial blockage over general anesthesia have been well characterized. A spinal injection has been associated with a decreased risk of major complications, deep venous thrombosis, pulmonary embolism, shorter operating room time, decreased blood loss, and lower blood transfusion rates compared to general anesthesia [23-26]. Peripheral nerve blocks and catheters are not routinely used for primary THA at our institution; however, the utility of lumbar plexus or fascia iliaca blocks to supplement postoperative pain control and attenuate intraoperative stress response deserves further investigation for this unique patient group [27]. Although prior studies are nonexistent looking at the THA outcomes after spine fusion, some parallels can be drawn from research with long rigid spine units in ankylosing spondylitis (AS). Tang and Chiu [16] reported on their group's experience with THA in patients with AS. They found a predilection for overly anteverted acetabular components that they attributed to the loss of lumbar lordosis, thoracic kyphosis, and compensatory pelvic hyperextension. Three dislocations were seen of 58 patients. All dislocations

Table 5 Bivariate Analysis of Predictor Variables. Reoperations

Age-groups (ref  60) 60-74.9 75 Sex: male (ref ¼ female) General anesthesia (ref ¼ single-shot spinal) Prior lumbar spine fusion (ref ¼ control) ASA score: 3 (ref ¼ 2) BMI  30 (ref  30) CCI (ref ¼ 0) 1 2 3

Complications

Nonhome Disposition

OR (95% CI)

P Value

OR (95% CI)

P Value

OR (95% CI)

P Value

0.86 0 0.51 5.47 5.67 0.47 2.4

.865 .994 .436 .035 .045 .382 .269

0.75 1.13 0.69 4.27 4.89 0.84 2.91

(0.21-2.73) (0.24-5.25) (0.23-2.02) (1.42-12.86) (1.63-14.68) (0.29-2.41) (1.00-8.42)

.663 .881 .493 .010 .005 .746 .049

1.65 7.74 0.47 1.01 1.55 4.24 0.8

(0.42-6.43) (1.72-34.79) (0.18-1.19) (0.35-2.90) (0.63-3.83) (1.65-10.93) (0.32-2.01)

.473 .008 .111 .988 .345 .003 .635

.617 .994 .995

1.45 (0.41-5.21) 0.68 (0.08-6.01) 1.09 (0.12-10.26)

.565 .730 .939

2.37 (0.79-7.14) 1.16 (0.22-6.22) 8.14 (1.35-49.03)

.123 .860 .022

(0.15-4.8) (0-Inf) (0.09-2.77) (1.13-26.54) (1.04-30.87) (0.09-2.55) (0.51-11.34)

1.55 (0.28-8.71) 0 (0-Inf) 0 (0-Inf)

All values listed in bold, P < .05. OR, odds ratio; CI, confidence interval; ASA, American Society of Anesthesiologist; BMI, body mass index; CCI, Charlson Comorbidity Index.

J.J. Barry et al. / The Journal of Arthroplasty xxx (2016) 1e5

were within the first 3 days postoperatively and 2 of them were anterior despite a posterior approach. AS patients obviously differ from our study cohort and often their spinal deformity is autofused in a deformed position. However, our group did also see 1 early dislocation in the SAHA group. Proper cup positioning in patients with rigid lumbopelvic units becomes very important. Limitations of this study are mostly related to being a small, retrospective, case-control study. Numbers available limited the ability to perform more complex statistics such as multivariate analysis to determine, for example, the independence of general anesthesia compared to spinal fusions causing increased rates of complications. The study population is also too small to detect significant differences in individual complication rates (infection, dislocation, etc). Additionally, definitively answering the pathophysiology of how a spinal fusion places a patient at risk for worse outcomes after a THA is outside the scope of this study. However, some inferences can be made especially when taking into account the findings seen for the longer spine fusion group. For example, we know from the spine literature that a spine arthrodesis places more stress and torque on the surrounding segments [28]. It is logical to extrapolate that the increased demand and altered biomechanics effect not only the spine but also the pelvis and hip joints, especially when the fusion mass extends to the pelvis. It is difficult to discern what effect this would have in the early postoperative setting but this may prove more important in the long term in regard to stability and wear. Despite the limitations, this investigation is the first to describe the suboptimal outcomes a prior LSF may predict for a primary THA. With the increasing utilization of LSF as a part of the treatment for multiple spinal conditions, arthroplasty surgeons are likely to see a growing number of these patients in their practice. A discussion of the increased risk with patients should be undertaken. Also, significant efforts should be made to use neuraxial or regional anesthesia whenever possible and minimize opioid use in this patient population. Further research into the pathophysiology of our findings as well as the long-term effects on stability, wear, and function is still needed. Conclusion Patients with preexisting LSF experience worse early postoperative outcomes after primary THA including higher rates of complications and reoperations. Prior spinal arthrodesis patients frequently require deviation from the standard intraoperative neuraxial anesthetic pathway and use significantly more opioid pain medication in the early postoperative period for pain control. These differences as well as functional and psychosocial factors that are poorly characterized likely all play a role in our findings. The complex interplay between the lumbar spine and hip warrants attention in THA candidates and represents an area for further investigation. References 1. Kurtz SM, Ong KL, Lau E, et al. Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021. J Bone Joint Surg Am 2014;96(8):624.

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