Obesity-related adipokines predict patient-reported shoulder pain

Increased Expression of Adipokines in Patients With Frozen Shoulder

BACKGROUND

Adipokines represent a spectrum of bioactive molecules that could modulate fibroblastic and inflammatory processes. The role of adipokines in the pathogenesis of frozen shoulder (FS), a common musculoskeletal disorder characterized by chronic inflammation, remains obscure.

PURPOSE

To evaluate whether adipokines contribute to the pathogenic mechanisms of FS and to evaluate any potential correlation of adipokines with patients' symptoms.

STUDY DESIGN

Controlled laboratory study.

METHODS

Shoulder capsule specimens were obtained from 10 patients with FS and 10 patients with shoulder instability (control group). The specimens were dyed using hematoxylin and eosin and immunohistochemically assessed with antibodies targeting adipokines, collagen I, collagen III, and tumor necrosis factor α. Immunoreactivity was graded from "no" to "strong" in a blinded manner. Reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) analysis was conducted. Before the surgery, patient-reported frequency of pain, severity of pain, stiffness, and shoulder range of motion were documented.

RESULTS

In comparison with the control group, patients with FS had significantly greater pain frequency, pain severity, and stiffness and more limited shoulder range of motion (P < .001). Hematoxylin and eosin- and Masson trichrome-stained samples from the FS group displayed hypercellularity and increased collagen fibers. Immunohistochemistry and RT-qPCR analyses indicated that expression of adipokines was significantly increased in FS capsules compared with the control group. The expression of collagen I, collagen III, and tumor necrosis factor α was also increased in FS capsules. No significant correlation was noted between adipokine expression and patient-reported outcomes in the control group, whereas in patients with FS, adiponectin expression was correlated with pain frequency (r = 0.78; P = .01) and stiffness (r = 0.73; P = .02). Visfatin was also correlated with pain frequency (r = 0.70; P = .02).

CONCLUSION/CLINICAL RELEVANCE

This study indicated a potential role for adipokines in the pathogenesis of FS and demonstrated a correlation between adipokine expression and patients' pain and stiffness.

Autologous fat grafting to the paravertebral space seems to prevent the postherpetic neuralgia-A single-arm pilot study

INTRODUCTION

Postherpetic neuralgia (PHN) is one of the most common complications of Herpes zoster (HZ), yet the mechanism and the treatment for PHN remains elusive. We first performed this feasibility study to verify the safety and efficiency of autologous fat grafting into the paravertebral space in early HZ to prevent PHN.

METHODS

Patients suffering from HZ with a rash in chest, back, or abdomen were arranged for autologous fat grafting to the paravertebral space. The primary endpoint was the incidence of PHN, which was defined as persistence pain in the affected dermal area in 12 weeks after fat grafting. Secondary endpoints including patient-reported changes in pain intensity, assessed pain threshold and the quality of life during follow-ups.

RESULTS

Eight patients accept the intervention and completed all follow-ups. Most patients report immediate pain relief after injection, one patient has a mild to moderate dizzy symptom after injection. No other short- or long-term adverse events occurred. For primary outcome, all patients have a timely reduced pain intensity, with no PHN events occurred, as all patients report pain intensity ≤3 in the VAS scale in 3 months after treatment. For electrical pain threshold, we identify that fat grafting differentially increases sensation and pain threshold in HZ area and healthy skin of patients. Besides, our results indicate significant improvement in patients' life quality decrease in analgesic consumption.

DISCUSSION

Autologous fat transplantation to the paravertebral space is a safe and feasible technique in preventing PHN from HZ in a rash. Further randomized controlled trial to investigate the actual long-term benefice of autologous fat grafting to the paravertebral space in preventing PHN is needed.

TRIAL REGISTRATION

ChiCTR, (ChiCTR1900025416); registered August 26, 2019.

Obesity does not associate with 5-year surgical complications following anatomic total shoulder arthroplasty and reverse total shoulder arthroplasty

BACKGROUND

Although obesity has been shown to increase the risk of short-term medical complications following total shoulder arthroplasty (TSA), evidence is lacking on the influence of obesity on longer-term surgical complications such as revision. The purpose of this study was to assess the association of increasing obesity with 2- and 5-year all-cause revision, periprosthetic joint infection (PJI), aseptic loosening, and manipulation under anesthesia (MUA) among patients undergoing reverse total shoulder arthroplasty (RTSA) or TSA.

METHODS

Patients who underwent RTSA or TSA with a minimum 5-year follow-up were identified in a national claims database (PearlDiver Technologies). Patients with obesity (body mass index [BMI] ≥30) were compared to patients who are normal or overweight (18.5 ≤ BMI < 30). Those with obesity were further stratified to those with class I or II obesity (30 ≤ BMI < 40) and those with class III obesity (BMI ≥ 40). Outcomes for comparison included all-cause revision, PJI, aseptic loosening, and MUA within 2 or 5 years. These cohorts were compared using univariate and multivariable analysis.

RESULTS

Patients with obesity had no significant difference in any surgical complication within 2 or 5 years for both those who underwent TSA or RTSA. After stratifying by class I or II obesity and class III obesity, there was still no significant difference in surgical complications with 2 or 5 years for both TSA patients and RTSA patients.

DISCUSSION

Obesity, when other major comorbidities are controlled for, was not associated with increased risk of long-term surgical complications after shoulder replacement surgery.

Decreased Expression of Leptin among Patients with Shoulder Stiffness

Shoulder stiffness (SS) is a disease that is fibroblastic and inflammatory in nature. Leptin is an adipokine-mediating the fibroblastic and inflammatory processes of various diseases. Our study tried to investigate the role of leptin in SS pathogenesis. Subacromial bursa from stiff and non-stiff shoulders were obtained for reverse transcription-polymerase chain reaction (RT-PCR) analysis and immunoblotting. Subacromial fluid was obtained for enzyme-linked immunosorbent assay. We showed that the expression level of leptin was lower in the subacromial bursae from the stiff shoulders in RT-PCR analysis (p < 0.001) and immunoblotting (p < 0.001). The concentration of leptin was also lower in the subacromial fluid derived from stiff shoulders. The leptin level in the subacromial fluid was positively associated with the constant score, total range of motion, flexion, abduction, and external rotation. The synovial fibroblasts derived from stiff shoulder-retrieved subacromial bursa were treated by 0, 1, and 3 μM leptin. Under RT-qPCR analysis, leptin was shown to dose-dependently decrease the transcription of IL-6, IL-10, and IL-13, but without impact on IL-1β and IL-4 (p < 0.001, p = 0.001, p = 0.001, p = 0.137, and p = 0.883 by ANOVA test, respectively). These results shed light on the role of leptin in orchestrating the disease processes of SS.

Lipid signatures of chronic pain in female adolescents with and without obesity

BACKGROUND

Chronic pain in adolescence is associated with diminished outcomes, lower socioeconomic status in later life, and decreased family well-being. Approximately one third of adolescents with chronic pain have obesity compared to the general population. In obesity, lipid signals regulate insulin sensitivity, satiety, and pain sensation. We determined whether there is a distinct lipid signature associated with chronic pain and its co-occurrence with obesity in adolescents.

METHODS

We performed global lipidomics in serum samples from female adolescents (N = 67, 13-17 years old) with no pain/healthy weight (Controls), chronic pain/healthy weight (Pain Non-obese), no pain/obesity (Obese), or chronic pain/obesity (Pain Obese).

RESULTS

The Pain Non-obese group had lipid profiles similar to the Obese and Pain Obese groups. The major difference in these lipids included decreased lysophosphatidylinositol (LPI), lysophosphatidylcholine (LPC), and lysophosphatidylethanolamine (LPE) in the three clinical groups compared to the Control group. Furthermore, ceramides and sphingomyelin were higher in the groups with obesity when compared to the groups with healthy weight, while plasmalogens were elevated in the Pain Obese group only.

CONCLUSIONS

Serum lipid markers are associated with chronic pain and suggest that specific lipid metabolites may be a signaling mechanism for inflammation associated with co-occurring chronic pain and obesity.

Is adiposity associated with back and lower limb pain? A systematic review

BACKGROUND

Back and lower limb pain have a major impact on physical function and quality of life. While obesity is a modifiable risk factor for musculoskeletal pain, the role of adiposity is less clear. This systematic review aimed to examine the relationship between both adiposity and its distribution and back and lower limb pain.

METHODS

A systematic search of electronic databases was conducted to identify studies that examined the association between anthropometric and/or direct measures of adiposity and site specific musculoskeletal pain. Risk of bias was assessed and a best evidence synthesis was performed.

RESULTS

A total of 56 studies were identified which examined 4 pain regions, including the lower back (36 studies), hip (two studies), knee (13 studies) and foot (eight studies). 31(55%) studies were assessed as having low to moderate risk of bias. 17(30%) studies were cohort in design. The best evidence synthesis provided evidence of a relationship between central adiposity and low back and knee pain, but not hip or foot pain. There was also evidence of a longitudinal relationship between adiposity and the presence of back, knee and foot pain, as well as incident and increasing foot pain.

CONCLUSIONS

This systematic review provides evidence of an association between both body fat and its central distribution and low back and knee pain, and a longitudinal relationship between adiposity and back, knee and foot pain. These results highlight the potential for targeting adiposity in the development of novel treatments at these sites.

Pressure pain thresholds in individuals with knee pain: a cross-sectional study

Background

Knee osteoarthritis (KOA), chronic widespread pain (CWP) and overweight/obesity are public health problems that often coincide, and there is a multifactorial and unclear relationship between them. The study aimed to (1) investigate pain sensitivity, assessed by pressure pain thresholds (PPTs), among women and men with knee pain and (2) associations with, respectively, radiographic KOA (rKOA), CWP, and overweight/obesity.

Methods

Baseline data from an ongoing longitudinal study involving 280 individuals with knee pain in the 30–60 age group. Pain sensitivity was assessed by PPTs on eight different tender points using a pressure algometer. The participants’ knees were x-rayed. Self-reported CWP and number of pain sites were assessed with a pain figure, and overweight/obesity was measured using body mass index (BMI), visceral fat area (VFA), and body fat percentage, assessed with a bioimpedance. Associations were analysed using regression analyses.

Results

Women reported lower PPTs than men (p < 0.001), but no PPTs differences were found between those with and without rKOA. Low PPTs was associated with female sex, more pain sites, CWP, and a higher VFA and body fat percentage. The tender points second rib and the knees were most affected. The prevalence of CWP was 38 %.

Conclusions

The modifiable factors, increased VFA, and body fat could be associated with increased pain sensitivity among individuals with knee pain. Longitudinal studies are needed to further investigate the associations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04408-0.

Circulating Adipokines in Predicting the Transition from Acute to Persistent Low Back Pain

OBJECTIVES

Cytokines such as tumor necrosis factor (TNF) contribute to the transition from acute to persistent pain. Despite increasing incidence of obesity and its linkage with chronic pain and inflammation, cytokines predominantly produced by adipose tissue (adipokines) have received little attention. Here we aimed to explore the longitudinal trajectory of adipokines from the onset of acute low back pain (LBP) and identify combinations of adipokines and/or other features that predict outcome.

METHODS

Individuals with acute LBP (less than two weeks after onset) who had either recovered (no pain, N = 15) or remained unrecovered (no reduction/increase in pain, N = 13) at six months and 15 controls were retrospectively selected from a larger prospective cohort. Participants provided blood for the measurement of TNF, interleukin-6 (IL-6), resistin, visfatin, adiponectin, leptin, and C-reactive protein (CRP), and completed questionnaires related to pain/disability, depression, and sleep at baseline. LBP participants repeated measurements at six months.

RESULTS

Compared with controls, acute LBP individuals had higher TNF and CRP but lower adiponectin. In LBP, unrecovered individuals had higher TNF at both time points, but lower CRP at baseline and leptin at six months. Although combined low CRP, high TNF, and depressive symptoms at baseline predicted poor recovery, the primary adipokines leptin, resistin, visfatin, and adiponectin did not.

CONCLUSIONS

Primary adipokines did not add to the prediction of poor LBP outcome that has been identified for the combination of low CRP, high TNF, and depressive symptoms in acute LBP. Whether adipokines play a role in LBP persistence in overweight/obese individuals requires investigation.

Circulating inflammatory biomarkers in adolescents: evidence of interactions between chronic pain and obesity

Introduction

The negative effects of chronic pain and obesity are compounded in those with both conditions. Despite this, little research has focused on the pathophysiology in pediatric samples.

Objective

To examine the effects of comorbid chronic pain and obesity on the concentration of circulating inflammatory biomarkers.

Methods

We used a multiple-cohort observational design, with 4 groups defined by the presence or absence of obesity and chronic pain: healthy controls, chronic pain alone, obesity alone, as well as chronic pain and obesity. Biomarkers measured were leptin, adiponectin, leptin/adiponectin ratio (primary outcome), tumor necrosis factor-alpha, interleukin 6, and C-reactive protein (CRP).

Results

Data on 125 adolescents (13-17 years) were analyzed. In females, there was an interaction between chronic pain and obesity such that leptin and CRP were higher in the chronic pain and obesity group than in chronic pain or obesity alone. Within the chronic pain and obesity group, biomarkers were correlated with worsened pain attributes, and females reported worse pain than males. The highest levels of interleukin 6 and CRP were found in youth with elevated weight and functional disability. We conclude that in adolescents, chronic pain and obesity interact to cause dysregulation of the inflammatory system, and this effect is more pronounced in females.

Conclusion

The augmented levels of inflammatory biomarkers are associated with pain and functional disability, and may be an early marker of future pain and disability.

Effects of a Fat-Rich Diet on the Spontaneous Release of Acetylcholine in the Neuromuscular Junction of Mice

Western societies are facing a clear increase in the rate of obesity and overweight which are responsible for musculoskeletal pain. Some of the substances described in the environment of myofascial trigger points (MTrPs) are the same as those found in the skeletal muscle of obese people, such as cytokines. Furthermore, elevated neuromuscular neurotransmission has been associated with MTrPs. The main objective of this study is to assess whether obesity or overweight may be a facilitator of myofascial pain. The experiments were performed on male Swiss mice. One experimental group was given a typical “cafeteria” diet and another group a commercial high-fat diet for six weeks. Intramuscular adipocytes were assessed with Sudan III. The functional study was performed with electromyographic recording to determine the plaque noise and intracellular recording of miniature endplate potentials (MEPPs). The intake of a cafeteria diet showed the presence of more adipocytes in muscle tissue, but not with the fat-supplemented diet. Both experimental groups showed an increase in the plaque noise and an increase in the frequency of MEPPs that lasted several weeks after interrupting diets. In summary, the supply of a hypercaloric diet for six weeks in mice increases spontaneous neurotransmission, thus facilitating the development of MTrPs.

The effect of obesity on pain and disability in chronic shoulder pain patients

OBJECTIVE

This study aimed to investigate the relationship between chronic shoulder pain and the increase in BMI.

METHODS

A prospective, cross-sectional study design was adopted for the study. Two hundred and eighty-five patients with chronic shoulder pain were evaluated for eligibility. A total of 94 patients were excluded from the study. The 191 remaining volunteers filled out a questionnaire (Pain (VAS), Shoulder Pain and Disability Index (SPADI)) and weight, height, C-reactive protein (CRP) results and 1-hour-rate of erythrocyte sedimentation rate (ESR) were measured. The participants were dived into the normal weight, overweight or obese group, considering the obesity classification defined by the World Health Organization (WHO).

RESULTS

A statistically significant correlation was found between the increase in BMI and pain (VAS), SPADI (pain, activity and total) and ESR. Although there was no statistically significant difference between the normal weight and overweight groups in all parameters, there was a statistically significant difference between the obese group and other groups.

CONCLUSIONS

Shoulder pain may associated with obesity and we recommend the addition of weight control to the treatment of patients with shoulder pain.

Serum soluble urokinase plasminogen activator receptor in adolescents: interaction of chronic pain and obesity

Pediatric chronic pain is exacerbated by obesity. Serum soluble urokinase plasminogen activator receptor, a novel inflammation biomarker, was increased in obese adolescents with chronic pain indicating interactive inflammatory conditions.

Introduction:

Obesity in adolescents is increasing in frequency and is associated with short-term and long-term negative consequences that include the exacerbation of co-occurring chronic pain.

Objective:

To determine whether the interaction between chronic pain and obesity would be reflected in changes in serum soluble urokinase plasminogen activator receptor (suPAR) concentrations, a novel marker of systemic inflammation associated with obesity, insulin resistance, and cardiovascular disease.

Methods:

We measured serum suPAR levels in 146 adolescent males and females with no pain or obesity (healthy controls; n = 40), chronic pain with healthy weight (n = 37), obesity alone (n = 41), and the combination of chronic pain and obesity (n = 28).

Results:

Serum suPAR (median [interquartile range]) was not increased by chronic pain alone (2.2 [1.8–2.4] ng/mL) or obesity alone (2.2 [2.0–2.4] ng/mL) but was increased significantly with the combination of chronic pain and obesity (2.4 [2.1–2.7] ng/mL; P < 0.019). This finding confirms the proposition that pain and obesity are inflammatory states that display a classic augmenting interaction.

Conclusion:

We propose that measurement of serum suPAR can be added to the armamentarium of serum biomarkers useful in the evaluation of mechanisms of inflammation in adolescent obesity and chronic pain.

Quantitative Sensory Testing in Adolescents with Co-occurring Chronic Pain and Obesity: A Pilot Study

Factors such as gender, ethnicity, and age affect pain processing in children and adolescents with chronic pain. Although obesity has been shown to affect pain processing in adults, almost nothing is known about pediatric populations. The aim of this pilot study was to explore whether obesity alters sensory processing in adolescents with chronic pain. Participants were recruited from a chronic pain clinic (Chronic Pain (CP), n = 12 normal weight; Chronic Pain + Obesity (CPO), n = 19 overweight/obesity) and from an obesity clinic (Obesity alone (O), n = 14). The quantitative sensory testing protocol included assessments of thermal and mechanical pain thresholds and perceptual sensitization at two sites with little adiposity. The heat pain threshold at the hand was significantly higher in the CPO group than in either the CP or O groups. Mechanical pain threshold (foot) was significantly higher in the CPO group than the CP group. No differences were found on tests of perceptual sensitization. Correlations between experimental pain and clinical pain parameters were found for the CPO group, but not for the CP group. This preliminary study provides important lessons learned for subsequent, larger-scale studies of sensory processing for youth with co-occurring chronic pain and obesity.

Obesity is Associated with an Increased Prevalence of Glenohumeral Osteoarthritis and Arthroplasty: A Cohort Study

The relationship between obesity and glenohumeral osteoarthritis is relatively understudied. The purpose of this study was to better define this relationship by age- and gender-matching 596,874 patients across six body mass index (BMI) cohorts and determining the prevalence of glenohumeral osteoarthritis and the standardized rate of glenohumeral arthroplasty in each cohort. Individuals with a BMI over 24 were found to be at increased odds for developing glenohumeral osteoarthritis, compared to the normal BMI cohort, and individuals with a BMI over 30 were additionally found to be at increased odds for undergoing glenohumeral arthroplasty.

Is there an association between metabolic syndrome and rotator cuff-related shoulder pain? A systematic review

Objectives

Rotator cuff-related shoulder pain (RCRSP) is a common upper limb complaint. It has been suggested that this condition is more common among people with cardiometabolic risk factors. This systematic review has synthesised evidence from case–control, cross-sectional and cohort studies on the association between metabolic syndrome (MetS) and RCRSP.

Design and data sources

Five medical databases (MEDLINE, EMBASE, SCOPUS, CINAHL and AMED) and reference checking methods were used to identify all relevant English articles that considered MetS and RCRSP. Studies were appraised using the Newcastle-Ottawa Scale (NOS). Two reviewers performed critical appraisal and data extraction. Narrative synthesis was performed via content analysis of statistically significant associations.

Results

Three cross-sectional, two case–control and one cohort study met the inclusion criteria, providing a total of 1187 individuals with RCRSP. Heterogeneity in methodology and RCRSP or MetS definition precluded a meaningful meta-analysis. Four of the included studies identified associations between the prevalence of MetS and RCRSP. Studies consistently identified independent cardiometabolic risk factors associated with RCRSP. All studies were level III evidence.

Summary and conclusion

The low-moderate quality evidence included in this review suggests an association between MetS and RCRSP. Most studies demonstrated moderate quality on appraisal. The direction of association and cardiometabolic factors influencing should be investigated by longitudinal and treatment studies. These preliminary conclusions and clinical utility should be treated with caution due to limitations of the evidence base.

Body Mass Index Screening in Knee Arthroscopy: An Analysis Using the National Surgical Quality Improvement Database

PURPOSE

To analyze patients undergoing knee arthroscopy stratified by body mass index (BMI) and assess the tradeoffs in complications avoided versus access to care that occur when instituting BMI eligibility criteria.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was used to identify patients who underwent knee arthroscopy from 2015 to 2016. Patients were categorized by BMI, and differences in complication rates between BMI categories were assessed. The positive predictive value (PPV) was calculated for various BMI cutoffs, with further analysis performed to identify the number of surgeries that would be denied to avoid a single complication.

RESULTS

There were 44,153 knee arthroscopy cases identified and an overall complication rate of 1.7%. There was no significant difference found in major complication rate between those with a BMI >40 kg/m² and those with a BMI <40 (1.7% vs 1.7%, P = .70), and no significant associations between increased complications and a higher BMI were found on binary logistic regression. Instituting a BMI cutoff of 40 has a PPV of 1.7% and would result in the avoidance of 11% of complications while denying 10% of otherwise uncomplicated surgeries. This cutoff would deny 57 surgeries for every complication avoided.

CONCLUSION

In patients undergoing knee arthroscopy, this study failed to detect a significant increased risk of major complications associated with having a BMI >40. The institution of BMI eligibility cutoffs would result in low PPVs and a high number of denials for surgery that would otherwise be complication free.

LEVEL OF EVIDENCE

Level IV, retrospective cohort-based database study.

Obesity is Independently Associated With Worse Patient-Reported Outcomes in Women with Systemic Lupus Erythematosus

OBJECTIVE

To determine whether obesity in women with systemic lupus erythematosus (SLE) is independently associated with worse patient-reported outcomes (PROs).

METHODS

Data were derived from a prospective study of adult women with a diagnosis of SLE that was verified by medical record review. Two established definitions for obesity were used: fat mass index (FMI) ≥13 kg/m² and body mass index (BMI) ≥30 kg/m² . Dependent variables included 4 validated PROs: disease activity as assessed by the Systemic Lupus Activity Questionnaire (SLAQ), depressive symptoms as assessed by the Center for Epidemiologic Studies Depression Scale (CES-D), pain as assessed by the Short Form 36 (SF-36) pain subscale, and fatigue as assessed by the SF-36 vitality subscale. We used multivariable linear regression to evaluate the associations of obesity with PROs, while controlling for potential confounders (age, race, education, income, smoking, disease duration, disease damage, and prednisone use).

RESULTS

The analysis included 148 participants, 32% of whom were obese. In the multivariate regression model, obesity was associated with worse scores for each PRO. Mean adjusted scores for the SLAQ and CES-D comparing obese versus non-obese participants were 14.8 versus 11.5 (P = 0.01) and 19.8 versus 13.1 (P < 0.01), respectively. The obese group also reported worse mean adjusted scores for pain (38.7 versus 44.2; P < 0.01) and fatigue (39.6 versus 45.2; P = 0.01).

CONCLUSION

In a representative sample of women with SLE, obesity (as defined by both FMI and BMI) was independently associated with worse PROs, including disease activity, depressive symptoms, and symptoms of pain and fatigue. Obesity may represent a modifiable target for improving outcomes among obese women with SLE.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

The Impact of Body Mass Index on Complications After Shoulder Arthroscopy: Should Surgery Eligibility Be Determined by Body Mass Index Cutoffs?

PURPOSE

The goal of this study is to analyze postoperative complications after shoulder arthroscopy stratified by body mass index (BMI) and to quantify the trade-off in postsurgical complications and access to care that occurs with BMI eligibility cutoffs.

METHODS

Patients who underwent shoulder arthroscopy in the National Surgical Quality Improvement Program database from 2015 to 2016 were identified. Patients were categorized on the basis of their BMI. χ² tests were used to identify differences in complication rates between different BMI categories. Logistic regression was used to calculate the odds ratio of having a major complication by BMI category. The positive predictive value (PPV) was calculated at different BMI cutoffs.

RESULTS

There were 26,509 shoulder arthroscopy cases identified in the National Surgical Quality Improvement Program database with 383 major complications, for an overall rate of 1.4%. Patients with a BMI >40 had a higher overall complication rate (2.3% vs 1.4%, P = .001), as well as higher rates of readmission (P = .012), pneumonia (P = .030), progressive renal insufficiency (P = .006), and cardiac arrest (P = .008). BMI >40 was associated with an increased risk of major complications (odds ratio, 1.84; confidence interval, 1.29-2.61). A BMI cutoff of 40 would avoid 12% of major complications while excluding 8% of complication-free surgeries. At a BMI cutoff of 40, the PPV was 2.3% where 43 surgeries would be denied for every complication avoided.

CONCLUSION

Patients with a BMI >40 have a statistically significant but only slightly increased risk of 30-day complications after shoulder arthroscopy. Instituting a BMI eligibility cutoff at 40 has a low PPV and would prevent 43 complication-free surgeries from proceeding for every complication prevented. Patients should be counseled individually about their risk factors, but denial of shoulder arthroscopy on the basis of BMI alone may not be an appropriate strategy for risk reduction.

LEVEL OF EVIDENCE

Level III, comparative prognostic trial.

Preoperative Serum Leptin Level Is Associated with Preoperative Pain Threshold and Postoperative Analgesic Consumption in Patients Undergoing Cesarean Section

OBJECTIVE

This study aimed to investigate the preoperative level of serum leptin in cesarean section (C-section) patients with and without acute labor pain and its association with postoperative analgesic consumption and preoperative pain threshold.

MATERIALS AND METHODS

Preoperative leptin levels, preoperative pain threshold, postoperative analgesic consumption in the first 24 h, and postoperative pain severity (visual analog scale (VAS) scores at 1, 2, 4, 6, 12, and 24 h postoperatively) in C-section patients with labor pain (emergency C-section; n = 21) and without labor pain (elective C-section; n = 25) were compared.

RESULTS

There were no significant differences between the groups regarding the demographic characteristics. Leptin levels, postoperative VAS scores, and analgesic consumption were significantly higher in the group with labor pain, while the preoperative pain threshold was lower. Serum leptin levels correlated negatively with pain threshold and positively with postoperative analgesic consumption. Multiple linear regression analyses in our study revealed that the preoperative leptin levels and having an emergency C-section independently affected the postoperative analgesic consumption and preoperative pain threshold, whereas their combined effects on these parameters were statistically not significant.

CONCLUSION

Preoperative levels of serum leptin were higher in C-section patients with labor pain than in those without labor pain, and increased serum leptin levels were associated with decreased preoperative pain threshold and increased postoperative analgesic consumption in our study population. Postoperative analgesic requirements may vary among patients, and their requirements might be predicted using preoperative indicators. Serum levels of leptin might be one such indicator and this warrants further studies with larger sample sizes.

The Role of Adipokines in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is an important cause of low back pain. Recent evidence suggests that in addition to abnormal and excessive mechanical loading, inflammation may be a key driver for both IDD and low back pain. Obesity, a known mechanical risk factor of IDD, is now increasingly being recognized as a systemic inflammatory state with adipokines being postulated as likely inflammatory mediators. The aim of this review was to summarize the current literature regarding the inflammatory role of adipokines in the pathophysiology of IDD. A systematic literature search was performed using the OVID Medline, EMBASE and PubMed databases to identify all studies assessing IDD and adipokines. Fifteen studies were included in the present review. Leptin was the most commonly assessed adipokine. Ten of 15 studies were conducted in humans; three in rats and two in both humans and rats. Studies focused on a variety of topics ranging from receptor identification, pathway analysis, genetic associations, and proteonomics. Currently, data from both human and animal experiments demonstrate significant effects of leptin and adiponectin on the internal milieu of intervertebral discs. However, future studies are needed to determine the molecular pathway relationships between adipokines in the pathophysiology of IDD as avenues for future therapeutic targets.

Adipokine Contribution to the Pathogenesis of Osteoarthritis

Recent studies have shown that overweight and obesity play an important role in the development of osteoarthritis (OA). However, joint overload is not the only risk factor in this disease. For instance, the presence of OA in non-weight-bearing joints such as the hand suggests that metabolic factors may also contribute to its pathogenesis. Recently, white adipose tissue (WAT) has been recognized not only as an energy reservoir but also as an important secretory organ of adipokines. In this regard, adipokines have been closely associated with obesity and also play an important role in bone and cartilage homeostasis. Furthermore, drugs such as rosuvastatin or rosiglitazone have demonstrated chondroprotective and anti-inflammatory effects in cartilage explants from patients with OA. Thus, it seems that adipokines are important factors linking obesity, adiposity, and inflammation in OA. In this review, we are focused on establishing the physiological mechanisms of adipokines on cartilage homeostasis and evaluating their role in the pathophysiology of OA based on evidence derived from experimental research as well as from clinical-epidemiological studies.

The Effects of Patient Obesity on Early Postoperative Complications After Shoulder Arthroscopy

PURPOSE

To report the prevalence of obesity in shoulder arthroscopy, determine a body mass index (BMI) threshold most predictive of complication within 30 days, and evaluate obesity as an independent risk factor for medical and surgical complications.

METHODS

Using the National Surgical Quality Improvement Program database, we reviewed all patients who underwent shoulder arthroscopy during 2011 to 2013. Receiver operating characteristic and Youden coefficient were calculated to find an optimal BMI cutoff to predict complications within 30 days of surgery. A case-control matched analysis was then performed by stratifying patient BMI by this cutoff and matching patients one to one according to age, sex, type of shoulder arthroscopy, American Society of Anesthesiology rating, surgical setting, and 8 comorbidities. Operating time, complications, and readmissions were also compared.

RESULTS

Of the 15,589 patients who underwent shoulder arthroscopy, 6,684 (43%) were classified as obese when using the optimal cutoff point of BMI = 30 according to the Youden coefficient. Obese patients had a higher risk of superficial site infection than nonobese patients (0.3% vs 0.0%; odds ratio [OR]: 6.00; 95% confidence interval [CI], 1.3 to 26.8; P = .015). Obese patients did not have significantly increased risk for overall early postoperative complication (1.2% compared with nonobese 0.8%; OR: 1.54; 95% CI, 1.0 to 2.4), readmissions (OR: 0.85; 95% CI, 0.5 to 1.5), or increased operating time (P = .068).

CONCLUSIONS

Up to 43% of patients undergoing shoulder arthroscopy can be classified as obese, but early perioperative complications are uncommon. Higher patient BMI is associated with increased risk of superficial site infection but not an overall risk for complication, readmission, or increased operating time.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Association of Leptin with Body Pain in Women

Leptin, an appetite-regulatory hormone, is also known to act as a proinflammatory adipokine. One of the effects of increased systemic leptin concentrations may be greater sensitivity to pain. We report the results of two studies examining the association between leptin and pain: a small pilot longitudinal study, followed by a large cross-sectional study. In Study 1, three women with physician-diagnosed fibromyalgia provided blood draws daily for 25 consecutive days, as well as daily self-reported musculoskeletal pain. Daily fluctuations in serum leptin were positively associated with pain across all three participants (F (1,63) = 12.8, p < 0.001), with leptin predicting ∼49% of the pain variance. In Study 2, the relationship between leptin and body pain was examined in a retrospective cross-sectional analysis of 5676 generally healthy postmenopausal women from the Women's Health Initiative. Leptin levels obtained from single blood draws were tested for a relationship with self-reported body pain. Body mass index (BMI) was also included as a predictor of pain. Both leptin and BMI were found to be independently associated with self-reported pain (p = 0.001 and p < 0.001, respectively), with higher leptin levels and greater BMI each being associated with greater pain. Leptin appears to be a predictor of body pain both within- and between-individuals and may be a driver of generalized pain states such as fibromyalgia.

Relationship between Neuropathic Pain and Obesity

Objectives. Overweight negatively affects musculoskeletal health; hence obesity is considered a risk factor for osteoarthritis and chronic low back pain. This was conducted to determine if obesity affects neuropathic pain, usually considered unrelated to the weight-load on the musculoskeletal system. Methods. Using a cut-off body mass index value of 25, 44 patients with neuropathic pain were grouped into a "high-BMI" group and a "normal-BMI" group. Results. The numeric rating scale of the high-BMI group was significantly higher than that of the normal-weight group (P < 0.05). The total NPSI scores were significantly higher (P < 0.01), and the paroxysmal pain and the negative symptoms were more serious in the high-BMI group than in the normal-BMI group. The high-BMI subjects also had significantly higher SF-MPQ scores (P < 0.05). However, both physical and mental health status on the SF-36 were comparable between the groups. Discussion. Neuropathic pain that did not arise from musculoskeletal damage was higher in the high-BMI patients. Paroxysmal pain was more severe, suggesting that neural damage might be aggravated by obesity-associated inflammation. These findings should have needed to be confirmed in future studies.