Clinical and Experimental 2014; 32: 401-403. BRIEF PAPER Radiological characteristics ABSTRACT the presence of erosions, and the often of the calcaneal spurs Objective. Inflammation at the enthe- exuberant appearance of the calcaneal ses is a distinguishing feature of pso- spurs, helps to distinguish inflammato- in riatic arthritis (PsA). at the ry spurs which occur in spondyloarthri- is the most common location at the tis including PsA, from those seen in D.D. Gladman1, M. Abufayyah2, Achilles and insertions patients with diffuse idiopathic skeletal D. Salonen3, A. Thavaneswaran4, on the calcaneus. This study aimed to hyperostosis (DISH) and osteoarthritis V. Chandran5 1) describe the morphological features (OA) (2). Since patients with PsA may 1University of Toronto, Toronto Western and measurements of plantar calcaneal also have coexistent OA and DISH, it Research Institute, and Director, Psoriatic spurs in subjects with PsA and controls is important to identify differentiating Arthritis Program, University Health and 2) determine radiological features features which would help recognise Network; that differentiate between inflammatory those spurs related to the inflammatory 2Clinical Research Fellow Psoriatic and non-inflammatory calcaneal spurs. process. There is little information on Arthritis Program, University Health Methods. Weight bearing lateral foot the characteristics of spurs occurring Network. Currently King Faisal radiographs of 101 subjects with PsA among patients with PsA. Specialist Hospital & Research Center, Jeddah, Saudi Arabia; and 38 control subjects without inflam- This study therefore aimed to: 3Department of Radiology, University matory arthritis were examined for 1. describe the morphological features Health Network, Toronto Western Hospital, plantar calcaneal and Achilles spurs. and measurements of plantar calcaneal Toronto, Ontario, Canada; Three measurements were taken from spurs on weight bearing lateral foot 4Biostatistician, Psoriatic Arthritis each radiograph: plantar spur base, radiographs in subjects with PsA and Program, University Health Network; mid-segment, and length in millim- controls and 5 University of Toronto, Deputy Director, eters. The differences in radiographic 2. determine radiological features that Psoriatic Arthritis Program, University Health Network. measurements, and the presence of differentiate between inflammatory and fluffy periostitis of the plantar spurs non-inflammatory calcaneal spurs. Dafna D. Gladman, MD, FRCPC Mohammed Abufayyah, MD were then compared between PsA pa- David Salonen, MD tients and controls. Methods Arane Thavaneswaran, MMath Results. Of the 101 subjects with PsA, Patient selection Vinod Chandran, MBBS, MD, DM, PhD 76 (75%) had at least one plantar cal- Patients with PsA followed at the Uni- Please address correspondence to: caneal spur and 32 (31.5%) had at least versity of Toronto PsA clinic were re- Dr Dafna D. Gladman, one spur, compared to cruited. Patients are followed at the Centre for Prognosis Studies in the 18 (47%) and 3 (8%) respectively in clinic at 6–12 month intervals at which Rheumatic Diseases, control group (p=0.004). Fluffy plantar time a complete history, physical ex- Toronto Western Hospital, periostitis was identified in 14 PsA sub- amination and laboratory assessments 399, Bathurst Street, 1E-410B Toronto, jects and none of the controls (p=0.01). are carried out. Radiographs are taken Ontario, M5T 2S8 Canada. The dimensions of plantar spurs were every 2 years, including weight bearing E-mail: [email protected] significantly different between groups lateral foot radiographs. Patients who Received on March 19, 2013; accepted in – longer mid-segment distinguished pa- were recorded as having spurs were revised form on October 19, 2013. tients with PsA from controls. identified. © Copyright Clinical and Conclusion. Calcaneal spurs are more Controls were patients without in- Experimental Rheumatology 2014. common in subjects with PsA than flammatory arthritis who had foot ra- controls. Longer mid-segment meas- diographs taken for other indications. Key words: psoriatic arthritis, urement was associated with PsA. These included patients with osteoar- calcaneal spurs, plantar spurs, This study indicates that the presence thritis or orthopedic conditions. enthesitis of fluffy plantar periostitis and broad based and longer mid-segment dimen- Assessments sions are radiological features for in- Weight bearing lateral foot radiographs flammatory spurs. were performed and examined for plantar and Achilles spurs. The pres- Introduction ence of spurs was recorded by one Inflammation at the enthesis is - adis observer (MA) who was instructed by tinguishing feature of psoriatic arthri- DS, a musculoskeletal radiologist. A tis (PsA) (1). Enthesitis at the heel is reliability study was not performed as the most common location occurring it has been shown that spurs are recog- at either the Achilles or plantar fascia nised reliably by rheumatologists (3). insertion on the calcaneus, and pre- Three measurements were taken from senting with irregular spiculated bony each radiograph: plantar spur base, Competing interests: none declared. proliferation. It has been suggested that mid-segment length, and length of the

401 BRIEF PAPER Calcaneal spurs in PsA / D.D. Gladman et al. entire spur in millimeters as shown in Figure 1. The presence of fluffy perios- titis was documented.

Statistical analysis The differences in radiographic meas- urements, and the presence of fluffy periostitis of the plantar spurs were then compared between PsA patients and controls using t-tests and Chi-squared analysis.

Results One hundred and one patients with PsA and 38 controls were included. Their characteristics are described in Table I. Of the 101 subjects with PsA, 76 (75%) had at least one plantar calca- neal spur and 32 (31.5%) had at least Fig. 1. Measurements of the Dimensions of Spurs. A: plantar spur base; B: mid-segment length; C: length of the entire spur. one Achilles tendon spur, compared to 18 (47%) and 3 (8%), respectively in control group (p=0.004). The presence of fluffy plantar periostitis was identi- fied in 14 PsA subjects but in none of the controls (p=0.01) (Table II). The di- mensions of plantar spurs were signifi- cantly different between groups (Table II). The base and mid segment of the spurs in PsA patients was wider than that in controls.

Discussion Calcanei are the most common sites for bony spurs. In a study of 121 adults from a prehistoric hunter-gatherer pop- ulation calcaneal spurs were scored as present or absent on the dorsal or plan- tar side and analysed in regards to their relationships with age, sex, osteoarthri- tis, cortical index, femoral head breadth Fig. 2. Fluffy spurs about the calcaneous. and muscle markers (4). The study demonstrated that calcaneal spurs fre- There was no gender effect but plantar plantar fascia thickness and fat pad ab- quencies increased with age, and there spurs correlated with and osteo- normalities resulted in the best group was a positive correlation with osteoar- arthritis. differentiation (p<0.0001) with sensi- thritis in both upper and lower limbs. When spurs are identified among - pa tivity of 85% and specificity of 95% Associations between the presence of tients with PsA the question is whether for plantar (7). calcaneal spurs and sex, body mass in- these are related to the underlying dis- Our study provides further evidence dex, radiographic measures of foot pos- ease or are due to concurrent condi- that calcaneal spurs are associated with ture, self-reported co-morbidities and tions such as DISH or OA. PsA. Although the frequency of spurs current or previous heel pain were ex- A recent study documented a rela- in the controls was high (at least one plored in a study of 140 women and 76 tionship between and plantar spur occurred in 31.5% of the men aged 62-94 (5). Of the 216 partici- calcaneal spurs (6). A study compar- patients, it was significantly higher pants, 119 (55%) had at least one plan- ing patients with plantar fasciitis with among the patients with PsA at 75%, tar and 103 (48%) had healthy controls found that calcaneal similar to the differences noted by Os- at least one Achilles tendon spur. Those spurs were common in both groups, borne et al. who compared patients with with plantar calcaneal spurs were more albeit more frequent in the plantar fas- plantar fasciitis to those without the likely to have Achilles tendon spurs. ciitis group (85% vs. 46%). However, clinical complaint (7). There was also a

402 Calcaneal spurs in PsA / D.D. Gladman et al. BRIEF PAPER

Table I. Demographic features of patients and controls. the PsA patients. Age has been associ- ated with the occurrence of spurs, but PsA Controls despite the expectation that older indi- Variable Mean (SD) or frequency (%) p-value viduals would have more spurs, we still n=101 n=38 found the prevalence higher among our PsA patients. Importantly, there was no Sex Males 65 (64.4%) 15 (39.5%) 0.008 statistically significant difference in the Females 36 (35.6%) 23 (60.5%) prevalence of obesity or DISH between Age 41.1 (10.8) 49.2 (14.7) 0.003 Obesity 42 (44.7%) 6 (46.1%) 0.92 the two groups. DISH 4 (4.0%) 0 (0.0%) 0.21 In summary, our study provides for the first time, radiological differenti- Table II. Spurs and their measurements in PsA and controls. ating features between inflammatory and non-inflammatory spurs including PsA Controls the presence of fluffy plantar periosti- Variable Mean (SD) or frequency (%) p-value tis and broad based and mid-segment

n=101 n=38 dimensions.

Plantar Spurs 76 (75.0%) 18 (47%) 0.0024 References Bilateral 56 11 1. HEALY PJ, HELLIWELL PS: Measuring clini- Unilateral 20 7 cal enthesitis in psoriatic arthritis: assess- Fluffy Plantar Spurs 14 (8.4%) 0 (0.0%) 0.013 ment of existing measures and development Achilles Spurs 32 (31.5%) 3 (8%) 0.004 of an instrument specific to psoriatic arthritis. Right Base 0.76 (0.30) 0.43 (0.14) Arthritis Rheum 2008; 59: 686-91. Left Base 0.70 (0.31) 0.54 (0.19) 2. SEBES JI: The significance of calcaneal spurs Base* 0.71 (0.28) 0.46 (0.15) <0.0001 in rheumatic diseases. Arthritis Rheum 1989; Right Mid 0.52 (0.23) 0.23 (0.08) 32: 338-40. Left Mid 0.49 (0.26) 0.26 (0.12) Mid* 0.49 (0.22) 0.23 (0.09) <0.0001 3. TAYLOR WJ, PORTER GG, HELLIWELL PS: Right Length 0.47 (0.24) 0.42 (0.19) Operational definitions and observer -reli Left Length 0.45 (0.24) 0.46 (0.18) ability of the plain radiographic features of Length* 0.45 (0.21) 0.42 (0.17) 0.57 psoriatic arthritis. J Rheumatol 2003; 30: 2645-58. *Base, Mid and Length is based on the unilateral measurement and if bilateral then an average of the 4. WEISS E: Calcaneal spurs: Examining etiol- left and right measurement was taken. ogy using prehistoric skeletal remains to un- derstand present day heel pain. Foot (Edinb) Online 2012/05/03. statistically significant difference in the were higher among the patients with PsA 5. MENZ HB, ZAMMIT GV, LANDORF KB, occurrence of Achilles insertion spurs compared to controls, while the length MUNTEANU SE: Plantar calcaneal spurs in older people: longitudinal traction or vertical in patients with PsA demonstrating a of the spurs did not distinguish between compression? J Foot Ankle Res 2008; 1: 7. much higher prevalence than those in inflammatory and non-inflammatory 6. JOHAL KS, MILNER SA: Plantar fasciitis the controls. Importantly, fluffy perios- spurs. Although there were more males and the calcaneal spur: Fact or fiction? Foot titis occurred only among patients with in our PsA group than in the controls Ankle Surg 2012; 18: 39-41. 7. OSBORNE HR, BREIDAHL WH, ALLISON GT: PsA. group, sex has not been found to be a Critical differences in lateral X-rays with and

The measurements of the plantar spurs, factor in the occurrence of spurs (5). On without a diagnosis of plantar fasciitis. J Sci in terms of the base and mid segment the other hand, controls were older than Med Sport 2006; 9: 231-7.

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