Investigations of Potential Phenotypes of Foot Osteoarthritis: Cross-Sectional Analysis From the Clinical Assessment Study of the Foot

Functional Imaging in Musculoskeletal Disorders in Menopause

Menopause-related musculoskeletal (MSK) disorders include osteoporosis, osteoarthritis (OA), sarcopenia and sarco-obesity. This review focuses on the applications of nuclear medicine for the functional imaging of the aforementioned clinical conditions. Bone Scan (BS) with 99mTc-labeled phosphonates, alone or in combination with MRI, can identify "fresh" vertebral collapse due to age-associated osteoporosis and provides quantitative parameters characterized by a good correlation with radiological indices in patients with OA. 18F-NaF PET, particularly when performed by dynamic scan, has given encouraging results for measuring bone turnover in osteoporosis and allows the evaluation of subchondral bone metabolic activity in OA. FDG PET can help discriminate between pathological and nonpathological vertebral fractures, especially by applying appropriate SUV-based thresholds. In OA, it can effectively image inflamed joints and support appropriate clinical management. Preliminary evidences suggest a possible application of FDG in sarco-obesity for the detection and quantification of visceral adipose tissue (VAT). Further studies are needed to better define the role of nuclear medicine in menopause-related MSK disease, especially as regards the possible impact of new radiopharmaceuticals (ie, FAPI and RGD peptides) and recent technological advances (eg, total-body PET/CT scanners).

Epidemiology of osteoarthritis: literature update 2022-2023

PURPOSE OF REVIEW

This review highlights recently published studies on osteoarthritis (OA) epidemiology, including topics related to understudied populations and joints, imaging, and advancements in artificial intelligence (AI) methods.

RECENT FINDINGS

Contemporary research has improved our understanding of the burden of OA in typically understudied regions, including ethnic and racial minorities in high-income countries, the Middle East and North Africa (MENA) and Latin America. Efforts have also been made to explore the burden and risk factors in OA in previously understudied joints, such as the hand, foot, and ankle. Advancements in OA imaging techniques have occurred alongside the developments of AI methods aiming to predict disease phenotypes, progression, and outcomes.

SUMMARY

Continuing efforts to expand our knowledge around OA in understudied populations will allow for the creation of targeted and specific interventions and inform policy changes aimed at reducing disease burden in these groups. The burden and disability associated with OA is notable in understudied joints, warranting further research efforts that may lead to effective therapeutic options. AI methods show promising results of predicting OA phenotypes and progression, which also may encourage the creation of targeted disease modifying OA drugs (DMOADs).

Structural Foot Characteristics in People With Midfoot Osteoarthritis: Cross-Sectional Findings From the Clinical Assessment Study of the Foot

OBJECTIVE

This study compared radiographic measures of foot structure between people with and without symptomatic radiographic midfoot osteoarthritis (OA).

METHODS

This was a cross-sectional study of adults aged 50 years and older registered with four UK general practices who reported foot pain in the past year. Bilateral weightbearing dorsoplantar and lateral radiographs were obtained. Symptomatic radiographic midfoot OA was defined as midfoot pain in the last 4 weeks, combined with radiographic OA in one or more midfoot joints (first cuneometatarsal, second cuneometatarsal, navicular-first cuneiform, and talonavicular). Midfoot OA cases were matched 1:1 for sex and age to controls with a 5-year age tolerance. Eleven radiographic measures were extracted and compared between the groups using independent sample t-tests and effect sizes (Cohen's d).

RESULTS

We identified 63 midfoot OA cases (mean ± SD age was 66.8 ± 8.0 years, with 32 male and 31 female participants) and matched these to 63 controls (mean ± SD age was 65.9 ± 7.8 years). There were no differences in metatarsal lengths between the groups. However, those with midfoot OA had a higher calcaneal-first metatarsal angle (d = 0.43, small effect size, P = 0.018) and lower calcaneal inclination angle (d = 0.46, small effect size, P = 0.011) compared with controls.

CONCLUSIONS

People with midfoot OA have a flatter foot posture compared with controls. Although caution is required when inferring causation from cross-sectional data, these findings are consistent with a pathomechanical pathway linking foot structure to the development of midfoot OA. Prospective studies are required to determine the temporal relationships between foot structure, function, and the development of this common and disabling condition.

Plantar pressures in people with midfoot osteoarthritis: cross-sectional findings from the Clinical Assessment Study of the Foot

BACKGROUND

Midfoot osteoarthritis (OA) is a common condition, however its aetiology is not well understood. Understanding how plantar pressures differ between people with and without midfoot OA may provide insight into the aetiology and how best to manage this condition.

RESEARCH QUESTION

To compare plantar pressures between people with and without symptomatic radiographic midfoot OA.

METHODS

This was a cross-sectional study of adults aged ≥ 50 years registered with four UK general practices who reported foot pain in the past year. Symptomatic radiographic midfoot OA was defined as midfoot pain in the last four weeks, combined with radiographic OA in one or more midfoot joints. Cases were matched 1:1 for sex and age ( ± 5 years) to controls. Peak plantar pressure and maximum force in 10 regions of the foot were determined using a pressure platform (RSscan International, Olen, Belgium) and compared between the groups using independent samples t-tests and effect sizes (Cohen's d).

RESULTS

We included 61 midfoot OA cases (mean age 67.0, SD 8.1, 31 males, 30 females) and matched these to 61 controls (mean age 66.0, SD 7.9). Midfoot OA cases displayed greater force (d=0.79, medium effect size, p = <0.001) and pressure at the midfoot (d=0.70, medium effect size, p = <0.001), greater force at the fourth metatarsophalangeal (MTP) joint (d=0.28, small effect size, p = 0.13), and fifth MTP joint (d=0.37, small effect size, p = 0.10) and greater pressure at the fifth MTP joint (d=0.34, small effect size, p = 0.13). They also displayed lower force (d=0.40, small effect size, p = 0.02) and pressure at the hallux (d=0.50, medium effect size, p = <0.001) and lower force (d=0.54, medium effect size, p = <0.001) and pressure at the lesser toes (d=0.48, small effect size, p = <0.001) compared with controls.

SIGNIFICANCE

Midfoot OA appears to be associated with lowering of the medial longitudinal arch, greater lateral push off and less propulsion at toe off. Longitudinal studies are needed to establish causal relationships.

Bone Marrow Lesions and Magnetic Resonance Imaging-Detected Structural Abnormalities in Patients With Midfoot Pain and Osteoarthritis: A Cross-Sectional Study

OBJECTIVE

To compare magnetic resonance imaging (MRI)-detected structural abnormalities in patients with symptomatic midfoot osteoarthritis (OA), patients with persistent midfoot pain, and asymptomatic controls, and to explore the association between MRI features, pain, and foot-related disability.

METHODS

One hundred seven adults consisting of 50 patients with symptomatic and radiographically confirmed midfoot OA, 22 adults with persistent midfoot pain but absence of radiographic OA, and 35 asymptomatic adults underwent 3T MRI of the midfoot and clinical assessment. MRIs were read for the presence and severity of abnormalities (bone marrow lesions [BMLs], subchondral cysts, osteophytes, joint space narrowing [JSN], effusion-synovitis, tenosynovitis, and enthesopathy) using the Foot Osteoarthritis MRI Score. Pain and foot-related disability were assessed with the Manchester Foot Pain and Disability Index.

RESULTS

The severity sum score of BMLs in the midfoot was greater in patients with midfoot pain and no signs of OA on radiography compared to controls (P = 0.007), with a pattern of involvement in the cuneiform-metatarsal joints similar to that in patients with midfoot OA. In univariable models, BMLs (ρ = 0.307), JSN (ρ = 0.423), and subchondral cysts (ρ = 0.302) were positively associated with pain (P < 0.01). In multivariable models, MRI abnormalities were not associated with pain and disability when adjusted for covariates.

CONCLUSION

In individuals with persistent midfoot pain but no signs of OA on radiography, MRI findings suggested an underrecognized prevalence of OA, particularly in the second and third cuneiform-metatarsal joints, where BML patterns were consistent with previously recognized sites of elevated mechanical loading. Joint abnormalities were not strongly associated with pain or foot-related disability.

Identifying Long-Term Trajectories of Foot Pain Severity and Potential Prognostic Factors: A Population-Based Cohort Study

OBJECTIVES

To identify distinct foot pain trajectories over 7 years and examine their associations with potential prognostic factors.

METHODS

Adults ages ≥50 years and registered with 4 general practices in North Staffordshire, UK were mailed a baseline health survey. Those reporting current or recent foot pain were invited to attend a research assessment clinic. Follow-up was by repeated postal surveys at 18, 36, 54, and 84 months. Distinct trajectories of foot pain were explored using latent class growth analysis (LCGA). Subsequently, identified trajectories were combined into most and least progressive groups, and covariate-adjusted associations with a range of prognostic factors were examined.

RESULTS

Of 560 adults with foot pain attending baseline research clinics, 425 (76%) provided data at baseline and 2 or more follow-up time points. LCGA for foot pain severity (0-10 numerical rating scale) identified a 4-trajectory model: "mild, improving" (37%); "moderate, improving" (33%); "moderate-severe, persistent" (24%); and "severe, persistent" (6%). Compared with individuals in more favorable (improving) pain trajectories, those in less favorable (persistent) pain trajectories were more likely to be obese, have routine/manual and intermediate occupations, have poorer physical and mental health, have catastrophizing beliefs, have greater foot-specific functional limitation, and have self-assessed hallux valgus at baseline.

CONCLUSIONS

Four distinct trajectories of foot pain were identified over a 7-year period, with one-third of individuals classified as having pain that is persistently moderate-severe and severe in intensity. The effect of intervening to target modifiable prognostic factors such as obesity and hallux valgus on long-term outcomes in people with foot pain requires investigation.

International Foot and Ankle Osteoarthritis Consortium review and research agenda for diagnosis, epidemiology, burden, outcome assessment and treatment

OBJECTIVE

To summarise the available evidence relating to the diagnosis, epidemiology, burden, outcome assessment and treatment of foot and ankle osteoarthritis (OA) and to develop an agenda to guide future research.

METHOD

Members of the International Foot and Ankle Osteoarthritis Consortium compiled a narrative summary of the literature which formed the basis of an interactive discussion at the Osteoarthritis Research Society International World Congress in 2021, during which a list of 24 research agenda items were generated. Following the meeting, delegates were asked to rank the research agenda items on a 0 to 100 visual analogue rating scale (0 = not at all important to 100 = extremely important). Items scoring a mean of 70 or above were selected for inclusion.

RESULTS

Of the 45 delegates who attended the meeting, 31 contributed to the agenda item scoring. Nineteen research agenda items met the required threshold: three related to diagnosis, four to epidemiology, four to burden, three to outcome assessment and five to treatment.

CONCLUSIONS

Key knowledge gaps related to foot and ankle OA were identified, and a comprehensive agenda to guide future research planning was developed. Implementation of this agenda will assist in improving the understanding and clinical management of this common and disabling, yet relatively overlooked condition.

A bibliometric analysis of published research employing musculoskeletal imaging modalities to evaluate foot osteoarthritis

Objectives

Temporal and global changes in research utilising imaging to assess foot osteoarthritis is currently unknown. This study aimed to undertake a bibliometric analysis of published research to: (1) identify the imaging modalities that have been used to evaluate foot osteoarthritis; (2) explore the temporal changes and global differences in the use of these imaging modalities; and (3) to evaluate performance related to publication- and citation-based metrics.

Methods

A literature search was conducted using Scopus to identify studies which had used imaging to assess foot osteoarthritis. Extracted data included publication year, imaging modality, citations, affiliations, and author collaboration networks. Temporal trends in the use of each imaging modality were analysed. Performance analysis and science mapping were used to analyse citations and collaboration networks.

Results

158 studies were identified between 1980 and 2021. Plain radiography was the most widely used modality, followed by computed tomography, magnetic resonance imaging (MRI) and ultrasound imaging (USI), respectively. The number of published studies increased over time for each imaging modality (all P ≥ 0.018). The most productive country was the United States of America (USA), followed by the United Kingdom and Australia. International authorship collaboration was evident in 57 (36.1%) studies. The average citation rate was 23.4 per study, with an average annual citation rate of 2.1.

Conclusions

Published research employing imaging to assess foot osteoarthritis has increased substantially over the past four decades. Although plain radiography remains the gold standard modality, the emergence of MRI and USI in the past two decades continues to advance knowledge and progress research in this field.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00549-0.

Ultrasound Imaging Acquisition Procedures for Evaluating the First Metatarsophalangeal Joint: A Scoping Review

The aim of this scoping review was to investigate ultrasound imaging (USI) acquisition procedures and guidelines used to assess the first metatarsophalangeal joint (MTPJ). MEDLINE, CINAHL, AMED and SPORTDiscus were systematically searched in May 2021. Studies were included if they used grey-scale USI or power Doppler and reported a USI procedure to assess the first MTPJ. Screening and data extraction were performed by two independent assessors. The scoping review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for scoping reviews (PRISMA-ScR). A total of 403 citations were identified for screening, with 36 articles included in the final analysis. There was wide variation in USI acquisition procedures used to evaluate the first MTPJ. Inconsistencies in reporting may be attributable to the number of elements the USI acquisition procedure encompasses, which include the model of the USI device, the type of transducer, USI modalities and settings, patient position, transducer orientation, surfaces scanned and the scanning technique used. The review found inconsistencies against international guidelines and limited implementation of consensus-based recommendations to guide image acquisition. Current guidelines require further refinement of anatomical reference points to establish a standardised USI acquisition procedure, subsequently improving interpretability and reproducibility between USI studies that evaluate the first MTPJ.

Foot structure and lower limb function in individuals with midfoot osteoarthritis: a systematic review

OBJECTIVE

To determine how foot structure and lower limb function differ between individuals with and without midfoot osteoarthritis (OA).

DESIGN

Electronic databases were searched from inception until May 2020. To be eligible, studies needed to (1) include participants with radiographically confirmed midfoot OA, with or without midfoot symptoms, (2) include a control group of participants without radiographic midfoot OA or without midfoot symptoms, and (3) report outcomes of foot structure, alignment, range of motion or any measures of lower limb function during walking. Screening and data extraction were performed by two independent assessors, with disagreements resolved by a third independent assessor. The methodological quality of included studies was assessed using the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.

RESULTS

A total of 1,550 records were screened by title and abstract and 11 met the inclusion criteria. Quantitative synthesis indicated that individuals who had midfoot OA had a more pronated foot posture, greater first ray mobility, less range of motion in the subtalar joint and first metatarsophalangeal joints, longer central metatarsals and increased peak plantar pressures, pressure time integrals and contact times in the heel and midfoot during walking. Meta-analysis could not be performed as the data were not sufficiently homogenous.

CONCLUSIONS

There are several differences in foot structure and lower limb function between individuals with and without midfoot OA. Future research with more consistent case definitions and detailed biomechanical models would further our understanding of potential mechanisms underlying the development of midfoot OA.

Identification of patterns of foot and ankle pain in the community: Cross-sectional findings from the clinical assessment study of the foot

OBJECTIVES

To investigate patterns of foot and ankle pain locations and symptoms, socio-demographic and comorbid characteristics to examine whether there are distinct foot and ankle pain phenotypes.

METHODS

Adults aged ≥50 years registered with four general practices in North Staffordshire were mailed a Health Survey questionnaire. Participants reporting foot pain in the last month indicated foot pain location on a foot manikin. Foot and ankle pain patterns were investigated by latent class analysis. Associations between the classes with foot pain symptoms, socio-demographic and comorbid characteristics were assessed.

RESULTS

Four thousand four hundred fifty-five participants with complete foot pain and manikin data were included in this analysis (mean age 65 years [SD 9.8], 49% male). Of those with foot and ankle pain (n = 1356), 90% had pain in more than one region. Six distinct classes of foot and ankle pain were identified: no pain (71%), bilateral forefoot/midfoot pain (4%), bilateral hindfoot pain (5%), left forefoot/midfoot pain (8%), right forefoot/midfoot pain (5%) and bilateral widespread foot and ankle pain (6%). People with bilateral widespread foot and ankle pain were more likely to be female, obese, depressed, anxious, have/had a manual occupation, have comorbidities, lower SF-12 scores and greater foot-specific disability. Age did not differ between classes.

CONCLUSIONS

Six distinct classes of foot and ankle pain locations were identified, and those with bilateral widespread foot and ankle pain had distinct characteristics. Further investigation of these individuals is required to determine if they have poorer outcomes over time and whether they would benefit from earlier identification and treatment.

Foot and Leg Muscle Weakness in People With Midfoot Osteoarthritis

OBJECTIVE

To compare foot and leg muscle strength in people with symptomatic midfoot osteoarthritis (OA) with asymptomatic controls, and to determine the association between muscle strength, foot pain, and disability.

METHODS

Participants with symptomatic midfoot OA and asymptomatic controls were recruited for this cross-sectional study from general practices and community health clinics. The maximum isometric muscle strength of the ankle plantarflexors, dorsiflexors, invertors and evertors, and the hallux and lesser toe plantarflexors was measured using hand-held dynamometry. Self-reported foot pain and foot-related disability were assessed with the Manchester Foot Pain and Disability Index. Differences in muscle strength were compared between groups. Multivariable regression was used to determine the association between muscle strength, foot pain, and disability after adjusting for covariates.

RESULTS

People with midfoot OA (n = 52) exhibited strength deficits in all muscle groups, ranging from 19% (dorsiflexors) to 30% (invertors) relative to the control group (n = 36), with effect sizes of 0.6-1.1 (P < 0.001). In those with midfoot OA, ankle invertor muscle strength was negatively and independently associated with foot pain (β = -0.026 [95% confidence interval (95% CI) -0.051, -0.001]; P = 0.045). Invertor muscle strength was negatively associated with foot-related disability, although not after adjustment for depressive symptoms (β = -0.023 [95% CI -0.063, 0.017]; P = 0.250).

CONCLUSION

People with symptomatic midfoot OA demonstrate weakness in the foot and leg muscles compared to asymptomatic controls. Preliminary indications from this study suggest that strengthening of the foot and leg muscles may offer potential to reduce pain and improve function in people with midfoot OA.

A 24-Month Follow-Up Study of the Effect of Intra-Articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis

Osteoarthritis (OA) is a widely prevalent disease worldwide, and with an increasingly ageing society, it has become a challenge for the field of regenerative medicine. OA is a disease process involving multiple joint tissues, including those not visible on radiography, and is a complex disease process with multiple phenotypes that require evaluation by a multimodality imaging assessment. The purpose of this study was to evaluate the effect of micro-fragmented fat tissue intra-articular injection 24 months after application in two ways: Indirectly using functional magnetic resonance imaging (MRI) assessment analyzing the glycosaminoglycans (GAG) content in cartilage by means of delayed gadolinium (Gd)-enhanced magnetic resonance imaging of cartilage (dGEMRIC), as well as clinical outcome on observed level of GAG using standard orthopedic physical examination including VAS assessment. In our previous study assessing comprehensive results after 12 months, the dGEMRIC results have drawn attention. The present study explores the long-term effect of intra-articular injection of autologous microfragmented adipose tissue to host chondrocytes and cartilage proteoglycans in patients with knee OA. A prospective, non-randomized, interventional, single-center, open-label clinical trial was conducted from January 2016 to April 2018. A total of 17 patients were enrolled in the study, and 32 knees were assessed in a 12-month follow-up, but only 10 patients of them with 18 knees are included in a 24-month follow-up. The rest of the seven patients dropped out of the study 12 months after follow-up: three patients underwent knee arthroplasty, and the remaining four did not fulfil the basic criteria of 24 months involvement in the study. Surgical intervention (lipoaspiration), followed by tissue processing and intra-articular injection of the final microfragmented adipose tissue product into the affected knee(s), was performed in all patients. Patients were assessed for a visual analog scale (VAS), dGEMRIC at the baseline, three, six, 12 and 24 months after the treatment. A magnetic resonance sequence in dGEMRIC due to infiltration of the anionic, negatively-charged contrast gadopentetate dimeglumine (Gd-DTPA2) into the cartilage indicated that the contents of cartilage glycosaminoglycans significantly increased in specific areas of the treated knee joint. Our results suggest that this method of single intra-articular injection of autologous microfragmented adipose tissue improves GAG content on a significant scale, with over half of the measurements suggesting relevant improvement 24 months after intra-articular injection opposed to the expected GAG decrease over the natural course of the disease.

Midfoot osteoarthritis: potential phenotypes and their associations with demographic, symptomatic and clinical characteristics

OBJECTIVE

To investigate the demographic, symptomatic, clinical and structural foot characteristics associated with potential phenotypes of midfoot osteoarthritis (OA).

DESIGN

Cross-sectional study of 533 community-dwelling adults aged ≥50 years with foot pain in the past year. Health questionnaires and clinical assessments of symptoms, foot structure and function were undertaken. Potential midfoot OA phenotypes were defined by the pattern of radiographic joint involvement affecting either the medial midfoot (talonavicular, navicular-1^st cuneiform, or cuneiform-1^st metatarsal joint), central midfoot (2^nd cuneiform-metatarsal joint), or both medial and central midfoot joints. Multivariable regression models with generalised estimating equations were used to investigate the associations between patterns of midfoot joint involvement and symptomatic, clinical and structural characteristics compared to those with no or minimal midfoot OA.

RESULTS

Of 879 eligible feet, 168 had medial midfoot OA, 103 central midfoot OA, 76 both medial and central midfoot OA and 532 no/minimal OA. Having both medial and central midfoot OA was associated with higher pain scores, dorsally-located midfoot pain (OR 2.54, 95%CI 1.45, 4.45), hallux valgus (OR 1.76, 95%CI 1.02, 3.05), flatter foot posture (β 0.44, 95%CI 0.12, 0.77), lower medial arch height (β 0.02, 95%CI 0.01, 0.03) and less subtalar inversion and 1^st MTPJ dorsiflexion. Isolated medial midfoot OA and central midfoot OA had few distinguishing clinical characteristics.

CONCLUSIONS

Distinct phenotypes of midfoot OA appear challenging to identify, with substantial overlap in symptoms and clinical characteristics. Phenotypic differences in symptoms, foot posture and function were apparent in this study only when both the medial and central midfoot were involved.

Foot structure, pain and functional ability in people with gout in primary care: cross-sectional findings from the Clinical Assessment Study of the Foot

Background

Gout frequently affects the foot yet relatively little is known about the effects of gout on foot structure, pain and functional ability. This study aimed to describe the impact of gout in a UK primary care population.

Methods

A cross-sectional study was nested within an observational cohort study of adults aged ≥50 years with foot pain. Participants with gout were identified through their primary care medical records and each matched on age (±2 years) and gender to four participants without gout. Differences in person-level variables (SF-12 Physical Component Score, Manchester Foot Pain and Disability Index and Short Physical Performance Battery) between gout and non-gout participants were determined using regression models. Differences in foot-level variables (pain regions, skin lesions, deformities, foot posture, and non-weightbearing range of motion) were determined using multi-level regression models. All models were adjusted for body mass index. Means and probabilities with 95% confidence intervals were calculated.

Results

Twenty-six participants with gout were compared to 102 participants without gout (77% male; mean age 66 years, standard deviation 11). Subtalar joint inversion and eversion and 1st metatarsophalangeal joint (MTPJ) dorsiflexion range of motion were significantly lower in the gout participants compared to the non-gout participants. Gout participants were more likely to have mallet toes and less likely to have claw toes compared to non-gout participants. There were no statistically significant differences in person-level variables, foot posture, ankle dorsiflexion range of motion, hallux valgus, pain regions, or skin lesions.

Conclusions

Non-weightbearing range of motion at the subtalar joint and 1st MTPJ was reduced in people with gout. Patients with gout who present with chronic foot problems should therefore undergo appropriate clinical assessment of foot structure.

Foot osteoarthritis: latest evidence and developments

Foot osteoarthritis (OA) is a common problem in older adults yet is under-researched compared to knee or hand OA. Most existing studies focus on the first metatarsophalangeal joint, with evidence relating to midfoot OA being particularly sparse. Symptomatic radiographic foot OA affects 17% of adults aged 50 years and over. The first metatarsophalangeal joint is most commonly affected, followed by the second cuneometatarsal and talonavicular joints. Epidemiological studies suggest the existence of distinct first metatarsophalangeal joint and polyarticular phenotypes, which have differing clinical and risk factor profiles. There are few randomized controlled trials in foot OA. Existing trials provide some evidence of the effectiveness for pain relief of physical therapy, rocker-sole shoes, foot orthoses and surgical interventions in first metatarsophalangeal joint OA and prefabricated orthoses in midfoot OA. Prospective epidemiological studies and randomized trials are needed to establish the incidence, progression and prognosis of foot OA and determine the effectiveness of both commonly used and more novel interventions.

Imaging of osteoarthritis-recent research developments and future perspective

In osteoarthritis research, imaging plays an important role in clinical trials and epidemiological observational studies. In this narrative review article, we will describe recent developments in imaging of osteoarthritis in the research arena, mainly focusing on literature evidence published within the past 3 years (2014-2017). We will primarily focus on MRI including advanced imaging techniques that are not currently commonly used in routine clinical practice, although radiography, ultrasound and nuclear medicine (radiotracer) imaging will also be discussed. Research efforts to uncover the disease process of OA as well as to discover a disease modifying OA drug continue. MRI continues to play a large role in these endeavors, while compositional MRI techniques will increasingly become important due to their ability to assess "premorphologic" biochemical changes of articular cartilage and other tissues in and around joints. Radiography remain the primary imaging modality for defining inclusion/exclusion criteria as well as an outcome measure in OA clinical trials, despite known limitations for visualization of OA features. Compositional MRI techniques show promise for predicting structural and clinical outcomes in OA research. Ultrasound can be a useful adjunct to radiography and MRI particularly for evaluation of hand OA. Newer imaging techniques such as hybrid PET/MRI may have a potential but require further research and validation.

Symptomatic Course of Foot Osteoarthritis Phenotypes: An 18-Month Prospective Analysis of Community-Dwelling Older Adults

Objective

Osteoarthritis (OA) is a heterogeneous disease, and symptom progression at the foot is unclear. This study investigated the symptomatic course of 3 predefined foot OA phenotypes over an 18‐month period.

Methods

The Clinical Assessment Study of the Foot is a community‐based cohort of adults ages ≥50 years in North Staffordshire, UK. Participants who reported foot pain in a postal health survey and underwent radiographic assessment were mailed an 18‐month followup survey. Changes in descriptive and symptomatic outcomes over 18 months were compared across the 3 phenotypes to determine within‐phenotype changes and between‐phenotype differences.

Results

Of 533 participants at baseline, 478 (89.7%) responded at 18 months. All 3 phenotypes showed small within‐phenotype improvements in mean foot pain severity (scale range 0–10, where 0 = no pain and 10 = worst pain): no or minimal foot OA (18 months 4.0, mean change −1.15 [95% confidence interval (95% CI) −1.46, −0.83]), isolated first metatarsophalangeal (MTP) joint OA (18 months 4.1, mean change −0.60 [95% CI −1.11, −0.10]), and polyarticular foot OA (18 months 5.1, mean change −0.77 [95% CI −1.42, −0.12]). The isolated first MTP joint OA phenotype had an increased likelihood of hallux valgus in the left foot (adjusted odds ratio 2.96 [95% CI 1.23, 7.12]) compared to the no or minimal foot OA phenotype.

Conclusion

Three foot OA phenotypes showed few descriptive or symptomatic changes over 18 months. Future clinical trials should consider that people recruited with mild‐to‐moderate symptomatic foot OA appear likely to remain relatively stable with usual care. Longer‐term followup using additional time points is required to describe further the natural history of foot OA.

Identification of Clusters of Foot Pain Location in a Community Sample

OBJECTIVE

To identify foot pain clusters according to pain location in a community-based sample of the general population.

METHODS

This study analyzed data from the North West Adelaide Health Study. Data were obtained between 2004 and 2006, using computer-assisted telephone interviewing, clinical assessment, and self-completed questionnaire. The location of foot pain was assessed using a diagram during the clinical assessment. Hierarchical cluster analysis was undertaken to identify foot pain location clusters, which were then compared in relation to demographics, comorbidities, and podiatry services utilization.

RESULTS

There were 558 participants with foot pain (mean age 54.4 years, 57.5% female). Five clusters were identified: 1 with predominantly arch and ball pain (26.8%), 1 with rearfoot pain (20.9%), 1 with heel pain (13.3%), and 2 with predominantly forefoot, toe, and nail pain (28.3% and 10.7%). Each cluster was distinct in age, sex, and comorbidity profile. Of the two clusters with predominantly forefoot, toe, and nail pain, one of them had a higher proportion of men and those classified as obese, had diabetes mellitus, and used podiatry services (30%), while the other was comprised of a higher proportion of women who were overweight and reported less use of podiatry services (17.5%).

CONCLUSION

Five clusters of foot pain according to pain location were identified, all with distinct age, sex, and comorbidity profiles. These findings may assist in the identification of individuals at risk for developing foot pain and in the development of targeted preventive strategies and treatments.

Predictors of foot pain in the community: the North West Adelaide health study

BACKGROUND

Foot pain has been shown to be prevalent across all age groups. The presence of foot pain may reduce mobility and impact on the ability to undertake activities of daily living. The aim of this study was to determine factors that are predictive of foot pain in a community based sample of the general population.

METHODS

This study analysed data from the North West Adelaide Health Study, a cohort study located in the northwestern suburbs of Adelaide, South Australia. Data were obtained between 2004-2006 and 2008-2010, using a self-completed questionnaire, computer assisted telephone interviewing, and a clinical assessment. The sensitivity, specificity and positive predictive values of variables were determined and generalised linear models ascertained the variables associated with the highest relative risk of self-reporting foot pain in 2008-2010 based on the data obtained in 2004-2006.

RESULTS

The prevalence of foot pain in 2004-2006 was 14.9 % (95 % CI 13.6-16.4) and in 2008-2010, 29.9 % (95 % CI 27.5-32.5). Variables with the highest sensitivity were: female sex, ever having back pain, self-reported arthritis, body mass index (BMI) classified as obese and having foot pain in 2004-2006, while most variables demonstrated high specificity. Those with the highest risk of reporting foot pain in 2008-2010 were those with depressive symptoms, self-reported arthritis, high BMI, self-reported upper limb pain and foot pain (in general or in specific regions of the foot) in 2004-2006.

CONCLUSION

Foot pain is common in the general population and those with the greatest risk of foot pain potentially represent a high level of chronicity and potential burden on the health system. Addressing the factors that predict foot pain, as well as the provision of targeted messages to highlight the importance of managing foot pain, may help reduce the impact on the population.

Animal models of osteoarthritis: classification, update, and measurement of outcomes

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.