Charcot-Marie-Tooth Disease of the Foot and Ankle: Imaging Features and Pathophysiology.

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral polyneuropathy, resulting in length-dependent motor and sensory deficiencies. Asymmetric nerve involvement in the lower extremities creates a muscle imbalance, which manifests as a characteristic cavovarus deformity of the foot and ankle. This deformity is widely considered to be the most debilitating symptom of the disease, causing the patient to feel unstable and limiting mobility. Foot and ankle imaging in patients with CMT is critical for evaluation and treatment, as there is a wide range of phenotypic variation. Both radiography and weight-bearing CT should be used for assessment of this complex rotational deformity. Multimodality imaging including MRI and US is also important to help identify changes in the peripheral nerves, diagnose complications of abnormal alignment, and evaluate patients in the perioperative setting. The cavovarus foot is susceptible to distinctive pathologic conditions including soft-tissue calluses and ulceration, fractures of the fifth metatarsal, peroneal tendinopathy, and accelerated arthrosis of the tibiotalar joint. An externally applied brace can assist with balance and distribution of weight but may be appropriate for only a subset of patients. Many patients will require surgical correction, which may include soft-tissue releases, tendon transfers, osteotomies, and arthrodesis when necessary, with the goal of creating a more stable plantigrade foot. The authors focus on the cavovarus deformity of CMT. However, much of the information discussed may also be applied to a similar deformity that may result from idiopathic causes or other neuromuscular conditions. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Why Do Some Patients Have Severe Sacroiliac Disease But No Syndesmophytes in Ankylosing Spondylitis? Data From a Nested Case-Control Study.

OBJECTIVE: Sacroiliac (SI) joint and spinal inflammation are characteristic of ankylosing spondylitis (AS), but some patients with AS have been identified who have discordant radiographic disease. We studied an AS subgroup with long-standing disease and fused SI joints. We identified factors associated with discrepant degrees of radiographic damage between the SI joints and spine. METHODS: From the Prospective Study of Outcomes in AS (PSOAS) cohort, patients with a disease duration ≥ 20 years and fused SI joints were included in a nested case-control design. Patients with and without syndesmophytes were used as cases and controls for analysis. We used classification and regression tree (CART) analysis to determine risk factors for syndesmophytes presence and reexamined the validity of the risk factors using univariable logistic regression models. RESULTS: There were 354 patients in the subgroup, 23 of whom lacked syndesmophytes. CART analysis showed females were less likely to have syndesmophytes. The next important predictor was age of symptom onset in males, with age of onset ≤ 16 years being less likely to have syndesmophytes. Univariable analysis confirmed females were less likely to have syndesmophytes (odds ratio [OR] 0.17, 95% CI 0.07-0.41). Syndesmophyte presence was associated with HLA-B27 positivity (P = 0.03) and age of symptom onset > 16 years old (OR 2.72, 95% CI 1.15-6.45). All 23 patients who lacked syndesmophytes were HLA-B27 positive. CONCLUSION: Using CART analysis and univariable modeling, women were less likely to have syndesmophytes despite advanced disease duration and SI joint disease. Patients with younger age of symptom onset were less likely to have syndesmophytes. All patients without syndesmophytes were HLA-B27 positive, indicating HLA-B27 positivity may be more associated with SI disease than spinal disease.

Risk Factors for Spinal Structural Damage in a Chinese Cohort With Ankylosing Spondylitis.

OBJECTIVES: A cross-sectional study was conducted in 270 Chinese patients with ankylosing spondylitis (AS) in order to identify potential risk factors for severity of spinal structural damage. METHODS: Two hundred seventy AS patients fulfilled the Modified New York Criteria. Computed tomography (CT) was used to scan sacroiliac and hip joints, and radiography was used to scan anteroposterior and lateral lumbar spine, as well as lateral cervical spine. Bath Ankylosing Spondylitis Radiology Index and modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) were scored in duplicate. RESULTS: One hundred eighty-three patients had low mSASSS (mSASSS, <10), and 87 patients had high mSASSS (mSASSS, ≥10). Univariate analysis revealed that AS age of onset, body mass index (BMI), smoking duration, duration of symptoms, diagnostic delay, hip involvement, and sacroiliitis grade were significantly associated with the risk of having high mSASSS after adjustment (all p's < 0.05). Hip involvement interacted significantly with BMI and smoking duration in a graded manner. Particularly, relative to patients with low BMI-negative hip involvement, those with high BMI-negative hip involvement, low BMI-positive hip involvement, and high BMI-positive hip involvement had a 1.94-fold, 3.29-fold, and 5.07-fold increased risk of high mSASSS (95% confidence interval, 0.84-4.47, 1.37-7.89, and 1.97-13.06, p = 0.118, 0.008, and 0.001, respectively). Finally, a nomogram graph based on 7 significant risk factors was generated with substantial prediction accuracy (concordance index, 0.906). CONCLUSIONS: We have identified 7 potential risk factors for the severity of spinal structural damage in Chinese AS patients. Importantly, positive hip involvement, combined with high BMI or long smoking duration, was associated with a remarkably increased risk of having severe spinal structural damage.

Identifying trajectories of radiographic spinal disease in ankylosing spondylitis: a 15-year follow-up study of the PSOAS cohort.

OBJECTIVES: Little is known with certainty about the natural history of spinal disease progression in ankylosing spondylitis (AS). Our objective was to discover if there were distinct patterns of change in vertebral involvement over time and to study associated clinical factors. METHODS: Data were analysed from the Prospective Study of Outcomes in Ankylosing Spondylitis (PSOAS) observational cohort. All patients met modified New York Criteria for AS and had ≥2 sets of radiographs scored by modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) by two independent readers between 2002 and 2017. Group-based trajectory modelling (GBTM) was used to classify patients into distinct groups of longitudinal mSASSS considering sociodemographic and clinical covariables. The optimal trajectory model and number of trajectories was selected using Nagin's Bayesian information criterion (BIC). RESULTS: A total of 561 patients with 1618 radiographs were analysed. The optimum number of trajectory groups identified was four (BIC -4062). These groups were subsequently categorized as: non-progressors (204 patients), late-progressors (147 patients), early-progressors (107 patients) and rapid-progressors (103 patients). Baseline predictors associated with higher spinal disease burden groups included: baseline mSASSS, male gender, longer disease duration, elevated CRP and smoking history. In addition, time-varying anti-TNF use per year was associated with decreased mSASSS progression only in the rapid-progressor group. CONCLUSIONS: GBTM identified four distinct patterns of spinal disease progression in the PSOAS cohort. Male gender, longer disease duration, elevated CRP and smoking were associated with higher spinal disease groups. Independent confirmation in other AS cohorts is needed to confirm these radiographic patterns.

Repeated Spinal Mobility Measures and Their Association With Radiographic Damage in Ankylosing Spondylitis.

OBJECTIVE: We sought to explore the relationship between changes in repeated mobility measures and spinal structural progression in patients with ankylosing spondylitis (AS) over time. METHODS: We studied patients with AS from the PSOAS (Prospective Study of Outcomes in AS) cohort and performed longitudinal multivariable regression modeling to assess the relationship of structural damage measured by their regional (cervical or lumbar) modified Stoke AS Spinal Score(mSASSS) and selected cervical (eg, cervical rotation, lateral bending, and occiput-to-wall distance) and lumbar spinal mobility measures (eg, Schöber's test and lumbar lateral bending) that were collected at least every 2 years from 2003 to 2019. RESULTS: The median length of follow-up for our 518 patients with cervical mSASSS measurements and 573 with lumbar mSASSS measurements was 4.08 (interquartile range [IQR] 2.25-6.67) and 4.17 (IQR 2.25-6.67) years, respectively. Among the mobility measures, based on multivariable regression models adjusting for clinical/demographic variables and C-reactive protein, we did not observe meaningful associations between changes in spinal mobility with their respective regional mSASSS. Baseline mSASSS, male sex, increased C-reactive protein (CRP), and longer disease duration were associated with increased longitudinal mSASSS in all analyses. CONCLUSION: Our study shows that 2-year changes in individual spinal mobility measures are not reliably associated with increased, longitudinal, AS-related spinal structural progression. We also confirmed the relationship of baseline mSASSS, sex, CRP, and disease duration with AS-related structural spinal progression over time.

The changing profile of ankylosing spondylitis in the biologic era.

OBJECTIVE: To compare disease characteristics, comorbidities, and medication utilization of 1141 patients with ankylosing spondylitis (AS) with short (< 20 years) and long (≥ 20 years) disease duration enrolled in the Prospective Study of Outcomes in AS (PSOAS) study over three different periods of time and followed longitudinally. METHODS: Study visits were carried out every 6 months examining disease activity (Bath AS Disease Activity Index (BASDAI), C-reactive protein, erythrocyte sedimentation rate), functional impairment, depression, and medication utilization as well as radiographic severity. Groups were compared with regression models using generalized estimating equation, linear, and Poisson regressions after adjusting for sites and for patients withdrawing from the study at less than 2 years follow-up. RESULTS: Overall, AS patients with long disease duration were more likely to be married, white, receiving disability, and to be with higher functional impairment and radiographic severity, more uveitis, diabetes, hypertension, cardiovascular disease, and osteoporosis, and with less nonsteroidal anti-inflammatory drug (NSAID) and more opioid use than those with short disease duration. Current smoking decreased between 2002 and 2019 regardless of disease duration. Lower baseline NSAID and methotrexate/sulfasalazine use and higher TNF inhibitor usage were seen only in those with shorter disease duration, though NSAID use and functional impairment decreased over time in both groups. Disease activity, depression scores, and NSAID use decreased and anti-TNF use increased in those followed > 8 years. CONCLUSIONS: Patients with AS enrolling in this multicenter longitudinal cohort have different disease profiles and medication utilization over time, perhaps reflecting innovations in treatment and increasing disease awareness. Key Points • The use of NSAIDs, nonbiologic DMARDs, and prednisone has decreased over the past 16 years in patients with AS. • The use of anti-TNF agents has dramatically increased. • In treated patients, disease activity, depression scores, and functional impairment have decreased over time.

Longitudinal associations between depressive symptoms and clinical factors in ankylosing spondylitis patients: analysis from an observational cohort.

OBJECTIVES: Although cross-sectional studies have shown that ankylosing spondylitis-specific factors correlate with depressive symptom severity, the association of these factors over time is unresolved. We examined the demographic and clinical factors associated with longitudinal depressive symptom severity in AS patients. METHODS: We analyzed sociodemographic, clinical, behavioral and medication data from 991 patients from the Prospective Study of Outcomes in Ankylosing spondylitis cohort, and measured depression severity with the Center for Epidemiological Studies Depression (CES-D) Scale administered at approximately 6-month visit intervals. Multivariable longitudinal negative binomial regression models were conducted using generalized estimating equation modeling to assess the demographic, clinical, and medication-related factors associated with depression severity by CES-D scores over time. RESULTS: The median baseline CES-D score (possible range 0-60) was 10.0 (interquartile range = 5, 17). In longitudinal multivariable analyses, higher CES-D scores were associated with longitudinal smoking, greater functional impairment, greater disease activity, self-reported depression, and poor global health scores. Marital status (e.g., being married) was associated with lower CES-D. Adjusted mean CES-D scores in our model decreased over time, with a significant interaction between time and gender observed. CONCLUSION: This study identified longitudinal clinical factors such as greater disease activity, greater functional impairment, and poor global health to be associated with longitudinal depression severity. These factors are potentially modifiable and may help manage depressive symptoms in AS.

Prevalence and Associations of Avascular Necrosis of the Hip in a Large Well-characterized Cohort of Patients With Inflammatory Bowel Disease.

OBJECTIVES: Avascular necrosis (AVN) is associated with significant morbidity potentially causing severe pain and disability; patients with inflammatory bowel disease (IBD) have a higher prevalence of AVN compared with non-IBD populations. The purpose of our study was to determine the prevalence of AVN in our IBD population and to evaluate these subjects for the presence of clinical characteristics associated with AVN on computed tomography (CT) imaging. METHODS: In 1313 IBD patients with abdomen/pelvis CT scans, we identified 27 patients (2.1%) with CT findings consistent with AVN. Through historical chart review, we confirmed that most patients had prior exposure to steroids, although 2 patients had no documented steroid exposure at all. RESULTS: We found that 59% of the concurrent radiology reports did not comment on the presence of AVN, suggesting that incidental CT findings of AVN among IBD patients are likely underreported. Notably, we found that 63% of these cases had documented complaints of low-back and/or hip pain. Using logistic regression, we found an association between anti-neutrophil cytoplasmic antibody-positive status across IBD (p = 0.007) and a smoking history in Crohn disease (p = 0.03) with the presence of AVN. CONCLUSIONS: We found that a significant proportion of IBD patients with AVN are reported in their records as having hip or low-back pain, and review of CT imaging under dedicated bone windows may identify AVN among this population. Our findings also suggest that additional etiological factors, beyond corticosteroids, contribute to the development of AVN in IBD. Further investigation is warranted regarding the mechanisms associated with AVN in IBD.

HLA class I and II alleles in susceptibility to ankylosing spondylitis.

OBJECTIVE: To examine associations of HLA class I and class II alleles with ankylosing spondylitis (AS) in three cohorts of patients of European, Asian and African ancestry. METHODS: HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1 and HLA-DPB1 alleles were genotyped in 1948 unrelated white and 67 African-American patients with AS from the Prospective Study of Outcomes in Ankylosing Spondylitis cohort, the North American Spondylitis Consortium and Australo-Anglo-American Spondyloarthritis Consortium, 990 white and 245 African-American Controls and HLA-B alleles in 442 Han Chinese patients with AS and 346 controls from Shanghai and Gansu, China. In addition to the case:control analyses, HLA-B*27-negative patients with AS were analysed separately, and logistic regression and 'relative predispositional effects' (RPE) analyses were carried out to control for the major effect of HLA-B*27 on disease susceptibility. RESULTS: Although numerous associations were seen between HLA alleles and AS in whites, among HLA-B*27-negative patients with AS , positive associations were seen with HLA-A*29, B*38, B*49, B*52, DRB1*11 and DPB1*03:01 and negative associations with HLA-B*07, HLA-B*57, HLA-DRB1*15:01, HLA-DQB1*02:01 and HLA-DQB1*06:02. Additional associations with HLA-B*14 and B*40 (B60) were observed via RPE analysis, which excludes the HLA-B*27 alleles. The increased frequency of HLA-B*40:01 and decreased frequency of HLA-B*07 was also seen in Han Chinese and African-Americans with AS. HLA-B*08 was decreased in whites with acute anterior uveitis. CONCLUSIONS: These data, analysing the largest number of patients with AS examined to date in three ethnic groups, confirm that other HLA class I and II alleles other than HLA-B*27 to be operative in AS predisposition.

Harmonization, data management, and statistical issues related to prospective multicenter studies in Ankylosing spondylitis (AS): Experience from the Prospective Study Of Ankylosing Spondylitis (PSOAS) cohort.

Ankylosing spondylitis (AS) is characterized by inflammation of the spine and sacroiliac joints causing pain and stiffness and, in some patients, ultimately new bone formation, and progressive joint ankyloses. The classical definition of AS is based on the modified New York (mNY) criteria. Limited data have been reported regarding data quality assurance procedure for multicenter or multisite prospective cohort of patients with AS. Since 2002, 1272 qualified AS patients have been enrolled from five sites (4 US sites and 1 Australian site) in the Prospective Study Of Ankylosing Spondylitis (PSOAS). In 2012, a Data Management and Statistical Core (DMSC) was added to the PSOAS team to assist in study design, establish a systematic approach to data management and data quality, and develop and apply appropriate statistical analysis of data. With assistance from the PSOAS investigators, DMSC modified Case Report Forms and developed database in Research Electronic Data Capture (REDCap). DMSC also developed additional data quality assurance procedure to assure data quality. The error rate for various forms in PSOAS databases ranged from 0.07% for medications data to 1.1% for arthritis activity questionnaire-Global pain. Furthermore, based on data from a sub study of 48 patients with AS, we showed a strong level (90.0%) of agreement between the two readers of X-rays with respect to modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). This paper not only could serve as reference for future publications from PSOAS cohort but also could serve as a basic guide to ensuring data quality for multicenter clinical studies.

Opioid Analgesic Use in Patients with Ankylosing Spondylitis: An Analysis of the Prospective Study of Outcomes in an Ankylosing Spondylitis Cohort.

OBJECTIVE: Opioid analgesics may be prescribed to ankylosing spondylitis (AS) patients with pain that is unresponsive to antirheumatic treatment. Our study assessed factors associated with opioid usage in AS. METHODS: A prospective cohort of 706 patients with AS meeting modified New York criteria followed at least 2 years underwent comprehensive clinical evaluation of disease activity and functional impairment. These were assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI). Radiographic severity was assessed by the Bath Ankylosing Spondylitis Radiology Index and modified Stokes Ankylosing Spondylitis Scoring System. Medications taken concurrently with opioids, as well as C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR), were determined at each study visit, performed every 6 months. Analyses were carried out at baseline, and longitudinal multivariable models were developed to identify factors independently associated with chronic and intermittent opioid usage over time. RESULTS: Factors significantly associated with opioid usage, especially chronic opioid use, included longer disease duration, smoking, lack of exercise, higher disease activity (BASDAI) and functional impairment (BASFI), depression, radiographic severity, and cardiovascular disease. Patients taking opioids were more likely to be using anxiolytic, hypnotic, antidepressant, and muscle relaxant medications. Multivariable analysis underscored the association with smoking, older age, antitumor necrosis factor agent use, and psychoactive drugs, as well as with subjective but not objective determinants of disease activity. CONCLUSION: Opioid usage was more likely to be associated with subjective measures (depression, BASDAI, BASFI) than objective measures (CRP, ESR), suggesting that pain in AS may derive from sources other than spinal inflammation alone.

Ethnicity and disease severity in ankylosing spondylitis a cross-sectional analysis of three ethnic groups.

The purpose of this study is to compare disease severity in ankylosing spondylitis (AS) in three ethnic groups. We assessed 925 AS patients (57 Blacks, 805 Whites, 63 Latinos) enrolled in the longitudinal Prospective Study of Outcomes in AS (PSOAS) for functional impairment, disease activity, and radiographic severity. Comparisons of clinical characteristics and HLA-B27 frequency for each group were performed, in two multivariable regression models, we compared the baseline Bath Ankylosing Spondylitis Radiographic Index (BASRI) and modified Stokes Ankylosing Spondylitis Spine Score (mSASSS) by ethnicity, adjusting for covariates. Blacks had greater functional impairment (Bath Ankylosing Spondylitis Functional Index) (median 62.5 vs. 27.8 in Whites and 38.1 in Latinos; p < 0.0001); higher disease activity (Bath Ankylosing Spondylitis Disease Activity Index), (median 5.9 vs. 3.5 in Whites and 4.5 in Latinos; p < 0.0001), erythrocyte sedimentation rate (median 27.0 in Blacks vs. 10.0 in Whites and 17.0; p < 0.0001), and C-reactive protein levels (median 1.2 vs. 0.4 mg/dL in Whites and 0.9 in Latinos; p < 0.0001). Baseline BASRI and mSASSS were higher in Blacks (mean 9.5 and median 38.2, respectively) compared to Whites (7.3 and 6.4) and Latinos (7.3 and 8.1), (p = 0.004, 0.007), respectively, more significant as disease duration increased. HLA-B27 occurred in 62.5% of Blacks, 85.3% of Whites, and 86.7% of Latinos (p < 0.0001). On multivariable analysis, higher BASRI and mSASSS were associated with Black ethnicity, after adjusting for disease duration and gender as well as TNF inhibitor (TNFi) usage, smoking status, or education level. Blacks with AS have more severe disease compared to either Whites or Latinos.

Spine fractures in ankylosing spondylitis: a case report and review of imaging as well as predisposing factors to falls and fractures.

BACKGROUND: Ankylosing spondylitis (AS), an inflammatory arthritis that affects the axial skeleton, predisposes patients with severe disease to falls and spinal fractures. Advanced imaging has improved the process of fracture detection. In spite of increased knowledge about early diagnosis and management of AS, little attention is being paid to the environmental hazards that pose a risk for patient outcome. OBJECTIVES: To identify risk factors for falls and fractures and evaluate imaging modalities in the detection of fractures in AS patients. METHODS: A case report and review of the literature using PubMed for English articles from 2000 to 2013 regarding AS patients׳ risk factors for falls and fractures and imaging modalities used to diagnose fracture in this population. RESULTS: Potential impairments in balance and coordination in the AS population include vestibular dysfunction, thoracolumbar kyphosis, and deficits in proprioception. A common and significant environmental risk factor for falls includes the use of a tub-shower arrangement. Furthermore, osteoporosis is a well-known complication of AS, which can predispose to a fracture. Lastly, there are no comprehensive studies that have evaluated the ability of advanced imaging modalities to identify an acute spine fracture in this patient population. CONCLUSIONS: AS patients with advanced disease are at an increased risk of falls and fractures due to many factors including but not limited to a rigid spine and difficulty with peripheral vision. A tub-shower arrangement commonly found in homes and hotel rooms is a major hazard. A consistent approach to diagnosis of fractures involving advanced imaging recommendations should be considered.

The impact of tumor necrosis factor α inhibitors on radiographic progression in ankylosing spondylitis.

OBJECTIVE: To study the effect of tumor necrosis factor α (TNFα) inhibitors on progressive spinal damage in patients with ankylosing spondylitis (AS). METHODS: All AS patients meeting the modified New York criteria who had been monitored prospectively and had at least 2 sets of spinal radiographs a minimum of 1.5 years apart were included in the study (n=334). The patients received standard therapy, which included nonsteroidal antiinflammatory drugs and TNFα inhibitors. Radiographic severity was assessed by the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Patients with a rate of AS progression that was ≥1 mSASSS unit/year were considered progressors. Univariable and multivariable regression analyses were done. Propensity score matching and sensitivity analysis were performed. A zero-inflated negative binomial (ZINB) model was used to analyze the effect of TNFα inhibitors on the change in the mSASSS with varying followup periods. Potential confounders, such as disease activity (as assessed by the Bath Ankylosing Spondylitis Disease Activity Index), the erythrocyte sedimentation rate, C-reactive protein level, HLA-B27 positivity, sex, age at onset, smoking burden (number of pack-years), and baseline damage, were included in the model. RESULTS: TNFα inhibitor treatment was associated with a 50% reduction in the odds of progression, with an odds ratio (OR) of 0.52 (95% confidence interval [95% CI] 0.30-0.88, P=0.02). Patients with a delay of >10 years in starting therapy were more likely to experience progression as compared to those who started earlier (OR 2.4 [95% CI 1.09-5.3], P=0.03). In the ZINB model, the use of TNFα inhibitors significantly reduced disease progression when the gap between radiographs was >3.9 years. The protective effect of TNFα inhibitors was stronger after propensity score matching. CONCLUSION: Treatment with TNFα inhibitors appears to reduce radiographic progression in AS patients, especially with early initiation and with longer duration of followup.

Limb-sparing surgery for distal femoral and proximal tibial bone lesions: imaging findings with intraoperative correlation.

OBJECTIVE: Our purpose is to present normal and abnormal imaging findings associated with endoprosthetic reconstruction after limb-salvage surgery. CONCLUSION: Endoprosthetic reconstruction varies with the location and size of the tumor, implant designs, and complications. Radiologists need to be aware of associated imaging findings seen in postoperative infection, tumor recurrence, and hardware failure. With a thorough understanding of the normal postoperative radiographic findings after complex reconstructions, subsequent abnormalities are readily identified and timely diagnosis can be obtained.

Regional radiographic damage and functional limitations in patients with ankylosing spondylitis: differences in early and late disease.

OBJECTIVE: Both radiographic damage and functional limitations increase with the duration of ankylosing spondylitis (AS). We examined whether radiographic damage contributed more to functional limitations in late AS than in early AS, and if the strength of association varied with the anatomic region of damage. METHODS: In this cross-sectional study of 801 patients with AS, we examined associations of the lumbar modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), the cervical mSASSS, lumbar posterior fusion, cervical posterior fusion, and hip arthritis with the Bath Ankylosing Spondylitis Functional Index (BASFI) and the Health Assessment Questionnaire modified for the spondyloarthritides (HAQ-S). RESULTS: Higher lumbar and cervical mSASSS scores were associated with more functional limitations, but there was an interaction between mSASSS scores and the duration of AS, such that the strength of their association with functional limitations decreased with increasing duration of AS. Cervical posterior fusion was associated with worse functioning independent of mSASSS scores. Hip arthritis was significantly associated with functional limitations independent of spinal damage measures. Among patients with AS duration ≥40 years, the number of comorbid conditions accounted for most of the variation in functioning. Results were similar for both the BASFI and the HAQ-S. CONCLUSION: Although both radiographic damage and functional limitations increase over time in AS, the relative contribution of radiographic damage to functional limitations is lower among patients with longstanding AS than with early AS, suggesting patients may accommodate to limited flexibility. Damage in different skeletal regions impacts functioning over the duration of AS. Functional limitations due to comorbidity supervene in late AS.

Functional limitations due to axial and peripheral joint impairments in patients with ankylosing spondylitis: are focused measures more informative?

OBJECTIVE: Functional limitations in ankylosing spondylitis (AS) may be due to peripheral joint or axial involvement. To determine if the Bath Ankylosing Spondylitis Functional Index (BASFI), an axial-focused measure, can detect limitations related to peripheral joint involvement equally as well as the Health Assessment Questionnaire modified for the spondyloarthropathies (HAQ-S), a peripheral arthritis-focused measure, and vice versa, we compared associations of each questionnaire with spinal and hip range of motion, peripheral arthritis, and enthesitis in patients with AS. METHODS: We examined patients every 4-6 months in this prospective longitudinal study. We used mixed linear models to analyze the associations between 10 physical examination measures and the BASFI and HAQ-S. RESULTS: We studied 411 patients for a median of 1.5 years (median 3 visits). In multivariate analyses, cervical rotation, chest expansion, lateral thoracolumbar flexion, hip motion, tender joint count, and tender enthesis count were equally strongly associated with the BASFI and HAQ-S. Peripheral joint swelling was more strongly associated with the HAQ-S. Individual items of the BASFI were more likely than items of the HAQ-S to be associated with unrelated physical examination measures (e.g., the association between difficulty rising from a chair and cervical rotation), which may have diminished the axial/peripheral distinction for the BASFI. CONCLUSION: The BASFI and HAQ-S had similar associations with impairments in axial measures, while the HAQ-S had stronger associations with the number of swollen peripheral joints. The HAQ-S should be considered for use in studies focused on spondyloarthritis with peripheral joint involvement.