Orthopedic disease burden in adult patients with symptomatic lumbar scoliosis: results from a prospective multicenter study

Justin S. Smith Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;

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Christopher I. Shaffrey Departments of Neurosurgery and Orthopedic Surgery, Duke University Medical Center, Durham, North Carolina;

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Christine R. Baldus Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;

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Michael P. Kelly Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;

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Elizabeth L. Yanik Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;

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Jon D. Lurie Department of Medicine, Dartmouth Medical School, Hanover, New Hampshire;

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Christopher P. Ames Department of Neurosurgery, University of California, San Francisco, California;

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Shay Bess Denver International Spine Center, Presbyterian St. Luke’s/Rocky Mountain Hospital for Children, Denver, Colorado; and

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Frank J. Schwab Hospital for Special Surgery, New York, New York

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Keith H. Bridwell Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;

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OBJECTIVE

Although the health impact of adult symptomatic lumbar scoliosis (ASLS) is substantial, these patients often have other orthopedic problems that have not been previously quantified. The objective of this study was to assess disease burden of other orthopedic conditions in patients with ASLS based on a retrospective review of a prospective multicenter cohort.

METHODS

The ASLS-1 study is an NIH-sponsored prospective multicenter study designed to assess operative versus nonoperative treatment for ASLS. Patients were 40–80 years old with ASLS, defined as a lumbar coronal Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20, or Scoliosis Research Society-22 questionnaire score ≤ 4.0 in pain, function, and/or self-image domains. Nonthoracolumbar orthopedic events, defined as fractures and other orthopedic conditions receiving surgical treatment, were assessed from enrollment to the 4-year follow-up.

RESULTS

Two hundred eighty-six patients (mean age 60.3 years, 90% women) were enrolled, with 173 operative and 113 nonoperative patients, and 81% with 4-year follow-up data. At a mean (± SD) follow-up of 3.8 ± 0.9 years, 104 nonthoracolumbar orthopedic events were reported, affecting 69 patients (24.1%). The most common events were arthroplasty (n = 38), fracture (n = 25), joint ligament/cartilage repair (n = 13), and cervical decompression/fusion (n = 7). Based on the final adjusted model, patients with a nonthoracolumbar orthopedic event were older (HR 1.44 per decade, 95% CI 1.07–1.94), more likely to have a history of tobacco use (HR 1.63, 95% CI 1.00–2.66), and had worse baseline leg pain scores (HR 1.10, 95% CI 1.01–1.19).

CONCLUSIONS

Patients with ASLS have high orthopedic disease burden, with almost 25% having a fracture or nonthoracolumbar orthopedic condition requiring surgical treatment during the mean 3.8 years following enrollment. Comparisons with previous studies suggest that the rate of total knee arthroplasty was considerably greater and the rates of total hip arthroplasty were at least as high in the ASLS-1 cohort compared with the similarly aged general US population. These conditions may further impact health-related quality of life and outcomes assessments of both nonoperative and operative treatment approaches in patients with ASLS.

ABBREVIATIONS

ASD = adult spinal deformity; ASLS = adult symptomatic lumbar scoliosis; HR = hazard ratio; NRS = numeric rating scale; ODI = Oswestry Disability Index; PCS = Physical Component Score; PI-LL = pelvic incidence to lumbar lordosis; PRO = patient-reported outcome; PT = pelvic tilt; SAE = serious adverse event; SF-12 = 12-Item Short-Form Health Survey; SRS-22 = Scoliosis Research Society-22; THA = total hip arthroplasty; TKA = total knee arthroplasty.

OBJECTIVE

Although the health impact of adult symptomatic lumbar scoliosis (ASLS) is substantial, these patients often have other orthopedic problems that have not been previously quantified. The objective of this study was to assess disease burden of other orthopedic conditions in patients with ASLS based on a retrospective review of a prospective multicenter cohort.

METHODS

The ASLS-1 study is an NIH-sponsored prospective multicenter study designed to assess operative versus nonoperative treatment for ASLS. Patients were 40–80 years old with ASLS, defined as a lumbar coronal Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20, or Scoliosis Research Society-22 questionnaire score ≤ 4.0 in pain, function, and/or self-image domains. Nonthoracolumbar orthopedic events, defined as fractures and other orthopedic conditions receiving surgical treatment, were assessed from enrollment to the 4-year follow-up.

RESULTS

Two hundred eighty-six patients (mean age 60.3 years, 90% women) were enrolled, with 173 operative and 113 nonoperative patients, and 81% with 4-year follow-up data. At a mean (± SD) follow-up of 3.8 ± 0.9 years, 104 nonthoracolumbar orthopedic events were reported, affecting 69 patients (24.1%). The most common events were arthroplasty (n = 38), fracture (n = 25), joint ligament/cartilage repair (n = 13), and cervical decompression/fusion (n = 7). Based on the final adjusted model, patients with a nonthoracolumbar orthopedic event were older (HR 1.44 per decade, 95% CI 1.07–1.94), more likely to have a history of tobacco use (HR 1.63, 95% CI 1.00–2.66), and had worse baseline leg pain scores (HR 1.10, 95% CI 1.01–1.19).

CONCLUSIONS

Patients with ASLS have high orthopedic disease burden, with almost 25% having a fracture or nonthoracolumbar orthopedic condition requiring surgical treatment during the mean 3.8 years following enrollment. Comparisons with previous studies suggest that the rate of total knee arthroplasty was considerably greater and the rates of total hip arthroplasty were at least as high in the ASLS-1 cohort compared with the similarly aged general US population. These conditions may further impact health-related quality of life and outcomes assessments of both nonoperative and operative treatment approaches in patients with ASLS.

In Brief

The study objective was to assess disease burden of other orthopedic conditions in patients with adult symptomatic lumbar scoliosis (ASLS) using a prospectively collected cohort. The findings demonstrate that patients with ASLS have high orthopedic disease burden, with almost 25% having a fracture or nonthoracolumbar orthopedic condition requiring surgical treatment during the mean 3.8-year follow-up. These conditions may impact health-related quality of life and outcomes assessments of both nonoperative and operative treatments for patients with ASLS.

Adult spinal deformity (ASD) has many etiologies, including untreated or residual adolescent idiopathic scoliosis, iatrogenic deformities, and degenerative pathologies.1,2 ASD is highly prevalent, especially among older individuals, affecting up to 68% of those at least 65 years of age.3,4 When patients are symptomatic, the health impact of ASD can be substantial, with disability scores comparable to those of patients with cancer, diabetes, and heart disease.5 However, the symptoms and disability of patients with ASD not only derive from their spinal pathologies, but also reflect the collective impact of comorbidities and degenerative conditions that accumulate with aging.6,7

For many adults with spinal deformity, their spinal disease may be the dominant driver of pain and disability, but other orthopedic conditions may also negatively contribute to health-related quality of life. These other orthopedic conditions can not only impact pain and function, but may also confound the determination of responses to operative and nonoperative treatments. Despite the potential collateral impact of other orthopedic conditions in patients with ASD, the nonthoracolumbar orthopedic disease burden has not been defined in this patient population.

Results of an NIH-funded trial of adult symptomatic lumbar scoliosis (ASLS), the most common form of ASD, have been recently reported.8 Our objective in the present study was to use this ASLS patient population to assess nonthoracolumbar orthopedic disease burden. In addition, we sought to identify demographic, clinical, and radiographic factors associated with greater nonthoracolumbar orthopedic disease burden in this population.

Methods

Patient Population and Data Collection

The current analysis used data from patients with ASLS who were prospectively enrolled in an NIH-sponsored multicenter trial (ASLS-1) between 2010 and 2014 with the aim of assessing the effectiveness of operative versus nonoperative treatment for ASLS.8 Nine centers in North America contributed patients and each center received IRB approval for study participation (see Appendix).

Enrollment criteria for ASLS-1 were patients 40–80 years old and the presence of ASLS. ASLS was defined as either idiopathic or de novo lumbar scoliosis with a Cobb angle ≥ 30°, and with a Scoliosis Research Society-22 (SRS-22) questionnaire score ≤ 4.0 in the domains of pain, function, and/or self-image, and/or an Oswestry Disability Index (ODI) score ≥ 20. Patients were excluded if they had excessive medical comorbidities, pregnancy, osteoporosis (t-score < −3.0 of the femoral neck), history of a thoracolumbar fusion or thoracolumbar decompression across multiple levels, grade 3–5 spondylolisthesis, congenital spine anomalies, scoliosis of neuromuscular etiology, or were considered to be at high risk of surgical morbidity or failure. Only patients deemed surgical candidates were offered enrollment.

At enrollment, patients willing to be randomized to either operative or nonoperative treatment were entered into the randomized study arm. Enrolled patients who declined randomization were entered into the observational study arm based on their treatment choice (operative or nonoperative). Details of randomization, treatments, and outcomes have been previously reported.8,9 Because the present study is focused on the development of nonspine orthopedic conditions and is not focused on treatment approach, operative and nonoperative patients in both the observational and randomized arms were included as a single cohort. As part of the baseline and follow-up assessments, each site collected serious adverse events (SAEs). SAEs, as defined by the study sponsor (NIH), were death or any event that was life-threatening, caused significant or permanent disability, resulted in new or prolonged hospitalization, or was unexpected but reasonably related to the treatment intervention.10 Based on reported SAEs, nonthoracolumbar orthopedic disease events, defined as fracture and orthopedic conditions requiring surgical treatment, were assessed from the time of study enrollment through the 4-year follow-up. Reported events are those collected prospectively from the time of study enrollment and do not include events predating enrollment. The present study focuses on significant orthopedic events (fractures and surgeries) that required hospital admission, because these were the most objectively collected as part of the trial. Except for fractures, which did not all require operative treatment, other nonthoracolumbar orthopedic events that did not require operative treatment were not included in the present analyses. For example, hip arthritis that required no treatment or was treated only with medications or steroid injection was not included, because such conditions can be subjective and were not consistently collected.

Data and Statistical Analysis

Baseline demographic, clinical, and patient-reported outcome (PRO) measures were summarized. Nonthoracolumbar orthopedic events were grouped by type, and the numbers and percentages of patients affected and rates per 100,000 person-years were calculated. Cox regression was used to estimate associations of demographic, clinical, radiographic, and PRO measures with time to a nonthoracolumbar orthopedic event. Bivariate unadjusted models were run, followed by two adjusted models: 1) a preliminary model, including all patient characteristics statistically significantly associated in bivariate models (p < 0.05); and 2) a final model, including all patient characteristics associated with p values < 0.10 in the preliminary model. A similar analysis was also performed for comparison of patients who either did or did not undergo an arthroplasty during follow-up. SAS software (version 9.4, SAS Institute) was used for statistical analyses. All statistical tests were two-sided, and a threshold alpha level of 0.05 was used for statistical significance.

Results

Patient Population

The ASLS-1 study included 286 patients: a randomized cohort of 63 patients and an observational cohort of 223 patients. At baseline, 142 patients enrolled with plans for operative treatment and 144 enrolled with plans for nonoperative treatment, based on either randomization in the randomized arm or patient choice in the observational arm. By 4 years, in the combined cohort, 6 patients had crossed over from planned operative to nonoperative treatment, and 40 patients had crossed over from nonoperative to operative treatment. Loss to follow-up/withdrawals were 12/286 (4.2%) at 2 years and 28/286 (9.8%) at 4 years. The overall 4-year follow-up rate was 81% (mean 3.8 ± 0.9 years). The 4-year as-treated cohorts included 173 operative and 113 nonoperative patients. The as-treated operative patients were those who received operative treatment at some point during enrollment, including patients who crossed over from nonoperative treatment. The as-treated nonoperative patients were those who only received nonoperative treatments.

Baseline characteristics of the total 286 patients are summarized in Table 1. The mean age was 60.3 years and the majority of patients were women (90%). Almost one-third had a history of depression/anxiety/psychiatric disorder, and 36% were either current or former tobacco/nicotine users. The baseline PRO measures reflect a population with moderate to severe pain and disability (Table 1).

TABLE 1.

Baseline characteristics of 286 patients who received operative or nonoperative treatment for ASLS

Patient ParameterValue (%)
Mean age ± SD, yrs60.3 ± 9.3
Mean BMI ± SD, kg/m2 26.8 ± 5.5
Males28 (9.8)
Race
 White268 (93.7)
 Black14 (4.9)
 Other4 (1.4)
Currently working/employed*171 (59.8)
History of depression/anxiety/psychiatric disorder88 (30.8)
Substance use
 Current or former tobacco/nicotine use104 (36.4)
 Current or former alcohol/drug use8 (2.8)
Mean baseline PROs ± SD
 SRS-22 subscore3.2 ± 0.5
 ODI35.0 ± 15.2
 NRS back pain6.0 ± 2.2
 NRS leg pain3.6 ± 3.0
 SF-12 MCS50.3 ± 11.0
 SF-12 PCS35.2 ± 10.0

MCS = Mental Component Score.

Includes part-time and full-time homemaker.

Nonthoracolumbar Orthopedic Procedures and Fractures

A total of 104 nonthoracolumbar orthopedic procedures and fractures were reported at the mean 3.8 ± 0.9 years of follow-up, with 69 patients affected (24.1%), and the overall rate of these events per 100,000 person-years was 9200 (95% CI 7557–11,099; Table 2). The estimated occurrence of these events at 2 years following ASLS intervention was 15.9% (95% CI 11.5%–20.1%) and at 4 years was 24.7% (95% CI 19.3%–29.8%). Thus, the majority of these events occurred within the first 2 years following ASLS intervention, particularly between the 1- and 2-year time points (Fig. 1). Overall, the most common event was arthroplasty. During the 3.8-year follow-up, 29 patients (10.1%) underwent 38 arthroplasties, resulting in a rate of 3362 per 100,000 person-years (95% CI 2419–4563; Table 2). The estimated occurrence of arthroplasty events at 2 years following ASLS intervention was 6.2% (95% CI 3.3%–9.0%) and at 4 years was 10.2% (95% CI 6.5%–13.9%; Fig. 2). Knee arthroplasty was the most common, accounting for two-thirds of the procedures, followed by procedures performed on the shoulder, hip, and hallux (Table 2). A total of 25 orthopedic fractures affected 23 patients (8.0%), with the most common fractures affecting the foot/ankle, patella, shoulder, wrist, and femur. Joint ligament/cartilage repairs were performed in 12 patients (4.2%) and most commonly involved the knee and shoulder. Other less common events included cervical decompression/fusion (n = 7), carpal tunnel release (n = 6), and hammer toe repair (n = 4).

TABLE 2.

Summary of nonthoracolumbar spine orthopedic procedures and fractures occurring among 286 patients within 4 years of enrollment in a study of operative versus nonoperative treatment for ASLS

Procedure/FractureNo. of EventsNo. (%) of Pts AffectedRate per 100,000 Person-Yrs (95% CI)
Arthroplasty3829 (10.1)3362 (2419–4563)
 Knee2520 (7.0)2212 (1466–3212)
 Shoulder65 (1.7)531 (221–1094)
 Hip65 (1.7)531 (221–1094)
 Hallux11 (0.3)88 (8–412)
Fracture2523 (8.0)2212 (1466–3212)
 Foot/ankle99 (3.1)796 (393–1453)
 Patella32 (0.7)265 (73–708)
 Shoulder33 (1.0)265 (73–708)
 Wrist22 (0.7)177 (35–567)
 Femur22 (0.7)177 (35–567)
 Cervical11 (0.3)88 (8–412)
 Pelvis11 (0.3)88 (8–412)
 Sacrum11 (0.3)88 (8–412)
 Toe11 (0.3)88 (8–412)
 Tibia11 (0.3)88 (8–412)
 Humerus11 (0.3)88 (8–412)
Joint ligament/cartilage repair1312 (4.2)1150 (644–1911)
 Knee65 (1.7)531 (221–1094)
 Rotator cuff repair44 (1.4)354 (118–841)
 Shoulder, NOS22 (0.7)177 (35–567)
 Elbow11 (0.3)88 (8–412)
Cervical decompression/fusion77 (2.4)619 (276–1216)
Carpal tunnel release64 (1.4)531 (221–1094)
Hammer toe repair44 (1.4)354 (118–841)
Miscellaneous surgery65 (1.7)531 (221–1094)
 Foot32 (0.7)265 (73–708)
 Wrist/hand/digit33 (1.0)265 (73–708)
Trigger finger release22 (0.7)177 (35–567)
Hip dislocation11 (0.3)88 (8–412)
Hip contracture11 (0.3)88 (8–412)
Cubital tunnel release11 (0.3)88 (8–412)
Total10469 (24.1)9200 (7557–11,099)

NOS = not otherwise specified.

FIG. 1.
FIG. 1.

Cumulative incidence of nonthoracolumbar orthopedic events. The solid black line represents an estimate. The gray dashed lines represent upper and lower 95% CIs. The 2-year estimate of an adverse event (AE) was 15.9% (95% CI 11.5%–20.1%), and the 4-year estimate was 24.7% (95% CI 19.3%–29.8%).

FIG. 2.
FIG. 2.

Cumulative incidence of arthroplasty events. The solid black line represents an estimate. The gray dashed lines represent upper and lower 95% CIs. The 2-year estimate of an arthroplasty event was 6.2% (95% CI 3.3%–9.0%), and the 4-year estimate was 10.2% (95% CI 6.5%–13.9%).

Associations of baseline demographics, radiographic parameters, and PROs and risk of a nonthoracolumbar orthopedic event were estimated (Table 3). In unadjusted analyses, higher risk of an event was observed in patients who were older, not employed, had a greater number of baseline comorbidities, were more likely to have a history of tobacco/nicotine use, had worse sagittal spinal deformity (pelvic tilt [PT] and pelvic incidence to lumbar lordosis [PI-LL] mismatch), and poorer baseline health-related quality of life (leg pain numeric rating scale [NRS] and 12-Item Short-Form Health Survey [SF-12] Physical Component Score [PCS]). On univariate analysis, patients with a thoracic coronal curve > 30° had a lower risk of an event. Adjusted hazard ratios (HRs) are provided for these factors (preliminary model) in Table 3. A final model was generated that included all remaining factors with p values < 0.10 after backward selection from the preliminary model. In the final adjusted model, factors associated with nonthoracolumbar orthopedic events were: greater age (HR 1.44, 95% CI 1.07–1.94), history of tobacco/nicotine use (HR 1.63, 95% CI 1.00–2.66), and greater baseline leg pain NRS score (HR 1.10, 95% CI 1.01–1.19; Table 3). Based on this model, the likelihood of a nonthoracolumbar orthopedic event in this patient population is increased by 44% for each decade increase in age, increased by 63% in those with a history of tobacco/nicotine use, and increased by 10% for each point increase of the baseline leg pain NRS score.

TABLE 3.

Comparison of baseline demographics, radiographic parameters, and PROs of 286 patients with ASLS with and without a nonthoracolumbar orthopedic event

Patient ParameterNonthoracolumbar Orthopedic EventHR (95% CI)Adjusted HR (95% CI)
No, n = 219Yes, n = 67Preliminary Model*Final Model*
Mean age ± SD, yrs, modeled per decade59.4 ± 9.863.3 ± 6.91.57 (1.19–2.06)1.35 (0.97–1.88)1.44 (1.07–1.94)
BMI, n (%)
 Underweight/normal102 (46.6)26 (38.8)Ref
 Overweight51 (23.3)20 (29.9)1.16 (0.65–2.07)
 Obese66 (30.1)21 (31.3)1.62 (0.90–2.90)
Male gender, n (%)24 (11.0)4 (6.0)0.57 (0.21–1.59)
Race, n (%)
 White204 (93.2)64 (95.5)Ref
 Black13 (5.9)1 (1.5)0.29 (0.04–2.11)
 Other2 (0.9)2 (3.0)2.81 (0.69–11.52)
Currently working/employed, n (%)138 (63.0)33 (49.3)0.58 (0.36–0.94)1.01 (0.57–1.78)
Median no. of baseline comorbidities (IQR)1 (1–2)2 (1–2)1.29 (1.08–1.56)1.05 (0.84–1.30)
Substance use, n (%)
 Current or former tobacco/nicotine use70 (32.0)34 (50.8)1.94 (1.20–3.13)1.60 (0.98–2.62)1.63 (1.00–2.66)
 Current or former alcohol/drug use6 (2.7)2 (3.0)1.07 (0.26–4.38)
Coronal plane
 Mean lumbar Cobb angle ± SD, modeled per 10°53.7 ± 14.450.9 (14.0)0.85 (0.71–1.02)
 Mean coronal balance (absolute value) ± SD, modeled per 10 mm22.9 ± 22.426.1 (20.9)1.04 (0.95–1.15)
 Thoracic curve >30°, %127 (58.0)29 (43.3)0.54 (0.33–0.87)0.73 (0.44–1.23)
 Mean global sagittal alignment ± SD, modeled per 10 mm39.9 ± 37.943.4 ± 32.21.02 (0.97–1.09)
 Mean PT ± SD, modeled per 10°23.4 ± 9.925.6 ± 8.11.31 (1.02–1.67)0.94 (0.64–1.37)
 Mean PI-LL mismatch ± SD, modeled per 10°15.7 ± 19.222.3 ± 15.71.19 (1.05–1.34)1.14 (0.94–1.38)1.12 (0.99–1.28)
Baseline PROs, mean ± SD
 SRS-22 subscore3.2 ± 0.53.1 ± 0.50.80 (0.52–1.23)
 ODI, modeled per 10 points34.1 ± 15.537.7 ± 13.71.15 (0.99–1.34)
 NRS back pain5.9 ± 2.26.2 ± 2.31.06 (0.95–1.18)
 NRS leg pain3.4 ± 3.04.3 ± 3.01.10 (1.02–1.19)1.09 (0.99–1.19)1.10 (1.01–1.19)
 SF-12 MCS, modeled per 10 points50.2 ± 10.950.7 ± 11.41.03 (0.82–1.28)
 SF-12 PCS, modeled per 10 points36.0 ± 10.332.6 ± 8.30.72 (0.56–0.92)0.99 (0.97–1.02)

IQR = interquartile range. Global sagittal alignment was assessed based on the C7–S1 sagittal vertical axis. Bolded values reflect HRs with 95% CIs that do not cross 1. Note that whether an HR reflects greater or lesser risk of an associated event depends on the directionality of the variable. For example, a greater ODI reflects worse disability, while a greater SF-12 PCS reflects less disability. Missing values included the following: PI-LL mismatch missing for 2 patients with events and 15 patients without; PT missing for 2 patients with an event and 15 patients without; coronal balance and sagittal balance missing for 1 patient without an event.

The preliminary model includes all the factors with statistically significant associations in the unadjusted models. The final model includes all factors left with p values < 0.10 after backward selection from the preliminary model.

Includes part-time and full-time homemaker.

Includes autoimmune disease, cancer, cardiac disease, circulatory disorders (artery), circulatory disorders (venous), depression/anxiety/psychiatric disorder history, diabetes, gastrointestinal disease, hypertension, infection history, lung disease/asthma, nervous system disorder, and renal disease.

Associations of baseline demographics, radiographic parameters, and PROs with risk of arthroplasty during study enrollment were also estimated (Table 4). Based on the final adjusted model, higher risk of arthroplasty was observed in patients who were of non-White, non-Black race compared to White race ("other," HR 5.37, 95% CI 1.24–23.27), were not working (HR for currently working/employed 0.29, 95% CI 0.13–0.68), and had worse baseline leg pain NRS score (HR 1.29, 95% CI 1.12–1.47; Table 4).

TABLE 4.

Comparison of baseline demographics, radiographic parameters, and PROs of 286 patients with ASLS with and without an arthroplasty performed

Patient ParameterArthroplastyHR (95% CI)Adjusted HR (95% CI)*
No, n = 257Yes, n = 29Preliminary ModelFinal Model
Mean age ± SD, yrs, modeled per decade59.9 ± 9.563.7 ± 6.91.62 (1.06–2.48)1.16 (0.67–1.99)
BMI, n (%)
 Underweight/normal118 (45.9)10 (34.5)Ref
 Overweight61 (23.7)10 (34.5)1.31 (0.53–3.23)
 Obese78 (30.4)9 (31.0)2.01 (0.84–4.84)
Male gender, n (%)28 (10.9)0 (0)
Race, n (%)
 White242 (94.2)26 (89.7)RefRefRef
 Black13 (5.1)1 (3.5)0.78 (0.11–5.76)0.53 (0.07–4.17)0.57 (0.08–4.27)
 Other2 (0.8)2 (6.9)8.38 (1.97–35.68)5.18 (1.07–25.08)5.37 (1.24–23.27)
Currently working/employed, n (%)163 (63.4)8 (27.6)0.23 (0.10–0.52)0.34 (0.13–0.88)0.29 (0.13–0.68)
Median no. of baseline comorbidities (IQR)1 (1–2)2 (1–3)1.44 (1.11–1.87)1.02 (0.74–1.39)
Substance use, n (%)
 Current or former tobacco/nicotine use88 (34.2)16 (55.2)2.14 (1.03–4.45)1.44 (0.65–3.21)
 Current or former alcohol/drug use7 (2.7)1 (3.5)1.15 (0.16–8.44)
Coronal plane
 Mean lumbar Cobb angle ± SD, modeled per 10°53.3 ± 14.450.6 ± 13.70.87 (0.67–1.14)
 Mean coronal balance (absolute value) ± SD, modeled per 10 mm23.1 ± 21.828.8 ± 24.11.09 (0.96–1.25)
 Thoracic curve >30°, n (%)145 (56.4)11 (37.9)0.48 (0.23–1.01)
 Mean global sagittal alignment ± SD, modeled per 10 mm39.6 ± 36.851.1 ± 34.11.08 (0.99–1.16)
 Mean PT ± SD, modeled per 10°23.5 ± 9.827.6 ± 6.31.56 (1.08–2.25)0.93 (0.51–1.69)
 Mean PI-LL mismatch ± SD, modeled per 10°16.4 ± 19.025.5 ± 12.21.27 (1.06–1.53)1.20 (0.89–1.61)1.20 (0.99–1.47)
Baseline PROs, mean ± SD
 SRS-22 subscore3.2 ± 0.53.0 ± 0.60.50 (0.26–0.94)1.34 (0.50–3.65)
 ODI, modeled per 10 points34.0 ± 14.943.2 ± 15.51.43 (1.14–1.81)1.15 (0.77–1.71)
 NRS back pain5.9 ± 2.26.4 ± 2.31.09 (0.92–1.29)
 NRS leg pain3.4 ± 3.05.6 ± 2.21.26 (1.12–1.43)1.26 (1.09–1.45)1.29 (1.12–1.47)
 SF-12 MCS, modeled per 10 points50.4 ± 10.749.1 ± 13.20.90 (0.66–1.25)
 SF-12 PCS, modeled per 10 points35.8 ± 10.130.4 ± 8.10.56 (0.37–0.84)0.94 (0.50–1.77)

Global sagittal alignment was assessed based on the C7–S1 sagittal vertical axis. Bolded values reflect HRs with 95% CIs that do not cross 1. Missing values included the following: PI-LL mismatch missing for 1 patient with arthroplasty and 16 patients without; PT missing for 1 patient with arthroplasty and 16 patients without; coronal balance and sagittal balance missing for 1 patient without an arthroplasty.

The preliminary model includes all the factors with statistically significant associations in the unadjusted models. The final model includes all factors left with p values < 0.10 after backward selection from the preliminary model.

Includes part-time and full-time homemaker.

Includes autoimmune disease, cancer, cardiac disease, circulatory disorders (artery), circulatory disorders (venous), depression/anxiety/psychiatric disorder history, diabetes, gastrointestinal disease, hypertension, infection history, lung disease/asthma, nervous system disorder, and renal disease.

Discussion

The health impact of symptomatic ASD is substantial,5 but this patient population, which tends to be elderly, may be affected by other health conditions that negatively contribute to health state. Given that ASD is an orthopedic and neurosurgical condition, these patients may also have an increased burden of other orthopedic pathologies. These other orthopedic conditions may confound the ability to accurately assess the specific health impact of spinal deformity and the potential benefits of operative and nonoperative treatments. The present study assesses the rates of nonthoracolumbar orthopedic events that occurred in a cohort of patients with ASD while enrolled in a prospective multicenter trial that assessed operative and nonoperative treatment for ASLS.

Among 286 patients with ASLS, a total of 104 nonthoracolumbar orthopedic events were reported, with 69 patients (24.1%) affected during a mean of 3.8 ± 0.9 years of study enrollment. Overall, this represents 9200 (95% CI 7557–11,099) events per 100,000 person-years. The present study is the first to report on the nonthoracolumbar orthopedic disease burden in ASD patients; therefore, there are no previous studies for direct comparisons. Several reports have documented the rate of arthroplasty in the US.11–15 Sloan and colleagues15 assessed the rates of total hip arthroplasty (THA) and total knee arthroplasty (TKA) in the US in 2014, which is comparable to the 2010–2014 enrollment period of the present study. They reported a TKA rate of 525.3 (95% CI 520.8–529.8) per 100,000 person-years in 2014 among the population aged 55–64 years. The present study population, with a mean age of 60 years, had a TKA rate of 2212 (95% CI 1466–3212) per 100,000 person-years. In the population aged 55–64 years, Sloan et al. reported a rate of THA in 2014 of 273.8 (95% CI 270.4–277.2) per 100,000 person-years. The rate of THA in the present series was 531 (95% CI 221–1094) per 100,000 person-years. Collectively, these comparisons suggest that the rate of TKA was considerably greater in the studied ASLS cohort compared with the similarly aged US general population, and that the rates of THA in the study population were at least as high as the similarly aged US general population.

Multiple baseline factors were associated with nonthoracolumbar orthopedic events including older age, history of tobacco/nicotine use, and greater severity of leg pain. The association between greater age and increased orthopedic events is not unexpected, because the most common events observed (arthroplasty, fracture, and joint ligament/cartilage repair) have all been reported to increase with age.14,16,17 Although leg pain is a common complaint among patients with ASD and not all of the reported orthopedic events were related to the lower extremities, greater severity of leg pain was still significantly associated with the overall occurrence of nonthoracolumbar orthopedic events. Although we assume that the leg pain reported by patients in this study is radicular and related to nerve root compromise, it is possible that for many patients with ASLS the reported leg pain may result at least in part from arthritis of the hips and knees. This suggests that a PRO measure that specifically distinguishes between radicular pain and hip or knee pain may be useful. Even after adjusting for the effects of age and severity of spinal deformity, patients with a history of current or past tobacco/nicotine use had a greater risk of experiencing a nonthoracolumbar orthopedic event during enrollment. Although controversy remains regarding an association between tobacco use and osteoarthritis, recent literature suggests potential direct effects on the proliferation and chondrogenic differentiation of mesenchymal stem cells.18

Arthroplasty was the most common nonthoracolumbar orthopedic event affecting the study population during enrollment. Factors associated with these events in the final predictive model included race, employment status, and leg pain. The association between race and risk of nonthoracolumbar orthopedic events should be interpreted cautiously, because the vast majority of patients (93.7%) enrolled in the trial were White, with only 4.9% identifying as Black, and 1.4% reporting a race of "other." In addition, the broad 95% CIs related to associations with race suggest an imprecise estimate of the HRs. The association between greater leg pain and arthroplasty may reflect added leg pain related to the hip or knee pathology, as noted for the overall model of other orthopedic events. Although this association became stronger when limited to assessment of arthroplasty events (HR 1.29 vs 1.1), it is still likely that the observed greater leg pain is multifactorial and due to a combination of neural compression and degenerative joint disease.

PRO measures are commonly used to assess health status and responses to treatment for many conditions. For ASD, commonly used and reported outcomes measures include the SRS questionnaire (SRS-22r or SRS-30), ODI, SF-12, and more recently, the Patient-Reported Outcomes Measurement Information System (PROMIS).19–22 The SF-12 and PROMIS are general measures of health status, and the ODI is focused primarily on low-back pain. Although the SRS questionnaire is the only disease-specific outcomes measure widely used for ASD, it was developed primarily for patients with adolescent idiopathic scoliosis and only subsequently validated for use in adults.23,24 However, there currently exists no disease-specific outcomes measure for ASD. Findings from the present study suggest that the burden of disease from other musculoskeletal conditions should be considered when assessing outcomes based on general health measures and support development of more disease-specific outcomes measures for ASD. Based on current PRO measures used for ASD, it is not possible to directly address the important question of how nonspine orthopedic disease conditions may impact outcomes of patients treated for adult scoliosis. Current outcomes measures also do not permit assessment of whether there is a threshold of nonspine orthopedic disease burden that may preclude effective surgical treatment of scoliosis.

Study Strengths and Limitations

The primary strength of this study is the prospective design, which included directed attention to collection of adverse events that occurred during study enrollment. In addition, the patient population is relatively homogenous, with a focus on ASLS that had not been previously surgically treated and was limited to patients at least 40 years of age. The primary limitation of the present study is the potential that the enrolled patients may not broadly reflect all ASD patients, because study inclusion criteria required that all patients must be candidates for surgical treatment. Thus, the findings may not be generalizable to a patient with symptomatic ASD who is not yet a surgical candidate. Another limitation is the inability to accurately quantify all orthopedic disease burden based on the data collected in the trial. For example, a patient with an arthritic hip or knee that was not surgically treated, or treated with an outpatient procedure during the study interval, would not have been captured. Thus, the nonthoracolumbar orthopedic disease burden defined in this study, although high, is still likely an underestimate of the overall burden. Lastly, it is possible that there may have been differences in healthcare access between the study population and the broader North American population that could confound comparisons.

Conclusions

Patients with ASLS have a high orthopedic disease burden beyond their spinal deformity, with almost 25% having a fracture or orthopedic condition requiring surgical treatment during the mean 3.8 ± 0.9 years following study enrollment. Factors associated with the occurrence of these other orthopedic events include older age, history of tobacco/nicotine use, and greater severity of leg pain at baseline. When evaluating and caring for patients with ASLS, it is important to recognize that these patients will continue to suffer from nonspine orthopedic disease that may require surgical treatment. These conditions may further impact health-related quality of life and impact outcomes assessments of both nonoperative and operative treatment approaches.

Appendix

Sites that contributed patients to the ASLS study were: Washington University School of Medicine, St. Louis, Missouri; University of Virginia Health System, Charlottesville, Virginia; Maryland Spine Center, Baltimore, Maryland; Northwestern University, Chicago, Illinois; Norton Leatherman Spine Center, Louisville, Kentucky; New York University, New York, New York; Hospital for Special Surgery, New York, New York; Hospital du Sacre-Coeur de Montreal, Quebec, Canada; and University Health Network, Toronto Western Hospital, Toronto, Ontario, Canada.

Acknowledgments

This study utilized data from a trial funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases Division of the NIH (grant no. 5RO1-ARO55176) and the Scoliosis Research Society.

Disclosures

Dr. Smith reports receiving consultancy fees from Zimmer Biomet, NuVasive, DePuy Synthes, Stryker, Cerapedics, and Carlsmed; receiving royalties from Zimmer Biomet, NuVasive, and Thieme; holding stock in Alphatec and NuVasive; receiving research funding to his institution from DePuy Synthes, International Spine Study Group Foundation (ISSGF), NuVasive, Stryker, and AO Spine; receiving fellowship grant funding to his institution from AO Spine and the Neurosurgery Research and Education Foundation; serving on the editorial boards of Journal of Neurosurgery: Spine, Neurosurgery, Operative Neurosurgery, and Spine Deformity; and serving on the Board of Directors of the Scoliosis Research Society (SRS), outside the submitted work. Dr. Shaffrey reports receiving grants from NIH, during the conduct of the study; personal fees from NuVasive, Medtronic, Zimmer Biomet, and SI Bone, outside the submitted work; having direct stock ownership in NuVasive; being a patent holder for Medtronic, NuVasive, and Zimmer Biomet; and receiving royalties from Medtronic and NuVasive. Dr. Kelly reports receiving grants from the NIH and the SRS during the conduct of the study; receiving grants from the Setting Scoliosis Straight Foundation, the ISSGF, and AO Spine, outside the submitted work; support of non–study-related clinical or research effort from DePuy/Synthes Spine; and honoraria from the Journal of Bone and Joint Surgery. Dr. Yanik reports receiving grants from the SRS during the conduct of the study; and grants from the NIH, Department of Defense, and Orthopaedic Research and Education Foundation, outside the submitted work. Dr. Lurie reports receiving grants from the NIH and SRS during the conduct of the study; and receiving grants from PCORI and FDA, and personal fees from Spinol and UpToDate, outside the submitted work. Dr. Ames reports receiving personal fees from Stryker, Biomet Zimmer Spine, DePuy Synthes, NuVasive, Next Orthosurgical, Medicrea, Medtronic, Titan Spine, ISSG, Operative Neurosurgery, SRS, Global Spinal Analytics, and UCSF, outside the submitted work. Dr. Bess reports being a consultant for K2 Stryker and Mirus; direct stock ownership in Progenerative Medical and Carlsmed; being a patent holder for K2 Stryker and NuVasive; receiving clinical or research support for the study described from the ISSGF; support of non–study-related clinical or research effort from Globus, ISSGF, NuVasive, Medtronic, DePuy Synthes, K2 Stryker, SI Bone, and Seaspine; and receiving royalties from K2 Stryker and NuVasive. Dr. Schwab reports being a consultant to Zimmer Biomet and Medtronic; receiving royalties from Medicrea, Zimmer Biomet, and Medtronic; and being on the executive committee for the ISSG. Dr. Bridwell reports receiving grants from the SRS during the conduct of the study.

Author Contributions

Conception and design: Smith, Shaffrey, Kelly, Ames, Bess, Schwab, Bridwell. Acquisition of data: Smith, Shaffrey, Baldus, Lurie, Schwab, Bridwell. Analysis and interpretation of data: Smith, Kelly, Yanik, Lurie, Ames, Bess, Bridwell. Drafting the article: Smith, Bridwell. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Smith. Statistical analysis: Yanik. Administrative/technical/material support: Bridwell.

References

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    Schwab F, Dubey A, Gamez L, et al. Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976). 2005;30(9):10821085.

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    Bess S, Line B, Fu KM, et al. The health impact of symptomatic adult spinal deformity: comparison of deformity types to United States population norms and chronic diseases. Spine (Phila Pa 1976). 2016;41(3):224233.

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    Miller EK, Neuman BJ, Jain A, et al. An assessment of frailty as a tool for risk stratification in adult spinal deformity surgery. Neurosurg Focus. 2017;43(6):E3.

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    Miller EK, Vila-Casademunt A, Neuman BJ, et al. External validation of the adult spinal deformity (ASD) frailty index (ASD-FI). Eur Spine J. 2018;27(9):23312338.

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    Kelly MP, Lurie JD, Yanik EL, et al. Operative versus nonoperative treatment for adult symptomatic lumbar scoliosis. J Bone Joint Surg Am. 2019;101(4):338352.

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    Smith JS, Kelly MP, Yanik EL, et al. Operative versus nonoperative treatment for adult symptomatic lumbar scoliosis at 5-year follow-up: durability of outcomes and impact of treatment-related serious adverse events. J Neurosurg Spine. 2021;35(1):6779.

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    National Institute of Arthritis and Musculoskeletal and Skin Diseases. Template and Guidelines for Developing a Multi-Site Manual of Operations and Procedures (MOOP). Published October 2017.Accessed May 9, 2020. https://www.niams.nih.gov/sites/default/files/multisite_moop_0.pdf

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    Inacio MCS, Paxton EW, Graves SE, et al. Projected increase in total knee arthroplasty in the United States—an alternative projection model. Osteoarthritis Cartilage. 2017;25(11):17971803.

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    Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89(4):780785.

    • Crossref
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    Kurtz SM, Lau E, Ong K, et al. Future young patient demand for primary and revision joint replacement: national projections from 2010 to 2030. Clin Orthop Relat Res. 2009;467(10):26062612.

    • Crossref
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  • 14

    Maradit Kremers H, Larson DR, Crowson CS, et al. Prevalence of total hip and knee replacement in the United States. J Bone Joint Surg Am. 2015;97(17):13861397.

  • 15

    Sloan M, Premkumar A, Sheth NP. Projected volume of primary total joint arthroplasty in the U.S., 2014 to 2030. J Bone Joint Surg Am. 2018;100(17):14551460.

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    Spahn G, Wolf J, Hofmann GO, Schiele R. Prevalence and distribution of knee cartilage lesions in sportspersons and non-sportspersons: results of a retrospective arthroscopic study Article in German. Sportverletz Sportschaden. 2013;27(1):3948.

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    Yang X, Qi Y, Avercenc-Leger L, et al. Effect of nicotine on the proliferation and chondrogenic differentiation of the human Wharton’s jelly mesenchymal stem cells. Biomed Mater Eng. 2017;28(s1):S217S228.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Bridwell KH, Glassman S, Horton W, et al. Does treatment (nonoperative and operative) improve the two-year quality of life in patients with adult symptomatic lumbar scoliosis: a prospective multicenter evidence-based medicine study. Spine (Phila Pa 1976). 2009;34(20):21712178.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Smith JS, Shaffrey CI, Berven S, et al. Operative versus nonoperative treatment of leg pain in adults with scoliosis: a retrospective review of a prospective multicenter database with two-year follow-up. Spine (Phila Pa 1976). 2009;34(16):16931698.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Smith JS, Shaffrey CI, Berven S, et al. Improvement of back pain with operative and nonoperative treatment in adults with scoliosis. Neurosurgery. 2009;65(1):8694.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Smith JS, Shaffrey CI, Glassman SD, et al. Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient age. Spine (Phila Pa 1976). 2011;36(10):817824.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Bridwell KH, Cats-Baril W, Harrast J, et al. The validity of the SRS-22 instrument in an adult spinal deformity population compared with the Oswestry and SF-12: a study of response distribution, concurrent validity, internal consistency, and reliability. Spine (Phila Pa 1976). 2005;30(4):455461.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Asher MA, Min Lai S, Burton DC. Further development and validation of the Scoliosis Research Society (SRS) outcomes instrument. Spine (Phila Pa 1976). 2000;25(18):23812386.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
Images and illustration from Akinduro et al. (pp 834–843). Copyright Tito Vivas-Buitrago. Published with permission.
  • FIG. 1.

    Cumulative incidence of nonthoracolumbar orthopedic events. The solid black line represents an estimate. The gray dashed lines represent upper and lower 95% CIs. The 2-year estimate of an adverse event (AE) was 15.9% (95% CI 11.5%–20.1%), and the 4-year estimate was 24.7% (95% CI 19.3%–29.8%).

  • FIG. 2.

    Cumulative incidence of arthroplasty events. The solid black line represents an estimate. The gray dashed lines represent upper and lower 95% CIs. The 2-year estimate of an arthroplasty event was 6.2% (95% CI 3.3%–9.0%), and the 4-year estimate was 10.2% (95% CI 6.5%–13.9%).

  • 1

    Smith JS, Shaffrey CI, Ames CP, Lenke LG. Treatment of adult thoracolumbar spinal deformity: past, present, and future. J Neurosurg Spine. 2019;30(5):551567.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Smith JS, Lafage V, Shaffrey CI, et al. Outcomes of operative and nonoperative treatment for adult spinal deformity: a prospective, multicenter, propensity-matched cohort assessment with minimum 2-year follow-up. Neurosurgery. 2016;78(6):851861.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Kebaish KM, Neubauer PR, Voros GD, et al. Scoliosis in adults aged forty years and older: prevalence and relationship to age, race, and gender. Spine (Phila Pa 1976). 2011;36(9):731736.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Schwab F, Dubey A, Gamez L, et al. Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976). 2005;30(9):10821085.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Bess S, Line B, Fu KM, et al. The health impact of symptomatic adult spinal deformity: comparison of deformity types to United States population norms and chronic diseases. Spine (Phila Pa 1976). 2016;41(3):224233.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Miller EK, Neuman BJ, Jain A, et al. An assessment of frailty as a tool for risk stratification in adult spinal deformity surgery. Neurosurg Focus. 2017;43(6):E3.

  • 7

    Miller EK, Vila-Casademunt A, Neuman BJ, et al. External validation of the adult spinal deformity (ASD) frailty index (ASD-FI). Eur Spine J. 2018;27(9):23312338.

  • 8

    Kelly MP, Lurie JD, Yanik EL, et al. Operative versus nonoperative treatment for adult symptomatic lumbar scoliosis. J Bone Joint Surg Am. 2019;101(4):338352.

  • 9

    Smith JS, Kelly MP, Yanik EL, et al. Operative versus nonoperative treatment for adult symptomatic lumbar scoliosis at 5-year follow-up: durability of outcomes and impact of treatment-related serious adverse events. J Neurosurg Spine. 2021;35(1):6779.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    National Institute of Arthritis and Musculoskeletal and Skin Diseases. Template and Guidelines for Developing a Multi-Site Manual of Operations and Procedures (MOOP). Published October 2017.Accessed May 9, 2020. https://www.niams.nih.gov/sites/default/files/multisite_moop_0.pdf

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Inacio MCS, Paxton EW, Graves SE, et al. Projected increase in total knee arthroplasty in the United States—an alternative projection model. Osteoarthritis Cartilage. 2017;25(11):17971803.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89(4):780785.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Kurtz SM, Lau E, Ong K, et al. Future young patient demand for primary and revision joint replacement: national projections from 2010 to 2030. Clin Orthop Relat Res. 2009;467(10):26062612.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Maradit Kremers H, Larson DR, Crowson CS, et al. Prevalence of total hip and knee replacement in the United States. J Bone Joint Surg Am. 2015;97(17):13861397.

  • 15

    Sloan M, Premkumar A, Sheth NP. Projected volume of primary total joint arthroplasty in the U.S., 2014 to 2030. J Bone Joint Surg Am. 2018;100(17):14551460.

  • 16

    Cortet B, Chauvin P, Feron JM, et al. Fragility fractures in France: epidemiology, characteristics and quality of life (the EPIFRACT study). Arch Osteoporos. 2020;15(1):46.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Spahn G, Wolf J, Hofmann GO, Schiele R. Prevalence and distribution of knee cartilage lesions in sportspersons and non-sportspersons: results of a retrospective arthroscopic study Article in German. Sportverletz Sportschaden. 2013;27(1):3948.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Yang X, Qi Y, Avercenc-Leger L, et al. Effect of nicotine on the proliferation and chondrogenic differentiation of the human Wharton’s jelly mesenchymal stem cells. Biomed Mater Eng. 2017;28(s1):S217S228.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Bridwell KH, Glassman S, Horton W, et al. Does treatment (nonoperative and operative) improve the two-year quality of life in patients with adult symptomatic lumbar scoliosis: a prospective multicenter evidence-based medicine study. Spine (Phila Pa 1976). 2009;34(20):21712178.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Smith JS, Shaffrey CI, Berven S, et al. Operative versus nonoperative treatment of leg pain in adults with scoliosis: a retrospective review of a prospective multicenter database with two-year follow-up. Spine (Phila Pa 1976). 2009;34(16):16931698.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Smith JS, Shaffrey CI, Berven S, et al. Improvement of back pain with operative and nonoperative treatment in adults with scoliosis. Neurosurgery. 2009;65(1):8694.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Smith JS, Shaffrey CI, Glassman SD, et al. Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient age. Spine (Phila Pa 1976). 2011;36(10):817824.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Bridwell KH, Cats-Baril W, Harrast J, et al. The validity of the SRS-22 instrument in an adult spinal deformity population compared with the Oswestry and SF-12: a study of response distribution, concurrent validity, internal consistency, and reliability. Spine (Phila Pa 1976). 2005;30(4):455461.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Asher MA, Min Lai S, Burton DC. Further development and validation of the Scoliosis Research Society (SRS) outcomes instrument. Spine (Phila Pa 1976). 2000;25(18):23812386.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation

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