Prevalence of chronic postsurgical pain after thoracotomy and total knee arthroplasty: a retrospective multicenter study in Japan (Japanese Study Group of Subacute Postoperative Pain)

Prevalence and risk factors of chronic postsurgical pain after lung cancer surgery and knee arthroplasty: a prospective multicenter cohort study in Japan

PURPOSE

Chronic postsurgical pain (CPSP) is being increasingly recognized as an important clinical problem. The purpose of this prospective multicenter study was to evaluate the prevalence and risk factors of CPSP at 3 months after surgery in a Japanese population.

METHODS

Adult patients who underwent lung cancer surgery (L) or knee arthroplasty (K) at university hospitals in Japan and provided informed consent were included. Perioperative demographic, clinical, and psychological data were collected. Postsurgical pain scores were assessed via face-to-face interviews at each time point. We also investigated analgesic use at each time point in patients with CPSP.

RESULTS

A total of 494 (L) and 194 (K) patients completed our interviews at all visits up to 3 months after surgery. The prevalence of clinically relevant CPSP was 10% (L) and 28% (K), respectively. In both cohorts, pain intensity at 1 month after surgery was moderately correlated with pain intensity at 3 months after surgery. Multivariate logistic regression analysis revealed significant associations between preoperative chronic pain, current smoking status, and open thoracotomy with CPSP in the lung cohort. However, no pre- or intraoperative risk factors were identified in the knee cohort. None of the CPSP patients used strong opioids.

CONCLUSIONS

The prevalence of CPSP after lung cancer surgery and knee arthroplasty among Japanese patients was comparable with prevalences previously reported in other countries. Subacute pain was significantly correlated with CPSP; however, further studies are needed to determine whether intensive treatment of subacute postsurgical pain can prevent the development of CPSP.

Effect of adductor canal block combined with infiltration between the popliteal artery and posterior capsular of the knee on chronic pain after total knee arthroplasty: a prospective, randomized, double-blind, placebo-controlled trial

INTRODUCTION

Total knee arthroplasty (TKA) is accompanied by severe postoperative pain, which is reported to be an important cause of chronic pain. Ultrasound-guided adductor canal block (ACB) combined with infiltration between the popliteal artery and posterior capsular of the knee (IPACK) has been proven to have a better effect on relieving acute pain after TKA. However, whether it has a significant effect on the incidence of chronic pain after TKA has not been reported. This trial was designed to investigate the effect of ultrasound-guided ACB combined with IPACK on the incidence and intensity of chronic pain after TKA.

METHODS

In this prospective, randomized, double-blind, placebo-controlled study, 100 subjects scheduled for TKA were randomly (1:1) divided into two groups: the ropivacaine group and the placebo group. Patients in each group received ultrasound-guided ACB + IPACK procedures with 0.25% ropivacaine or equal volume normal saline. All patients received multimodal analgesia. Pain intensity was assessed using the Numerical Rating Scale (NRS). The primary outcome was the incidence of chronic pain at 3 months after TKA by telephone follow-up. In addition, pain intensity in early resting and mobilized states, chronic pain intensity, the time to first rescue analgesia; opioid consumption; CRP and IL-6 after the operation; length of postoperative hospital stay; and cost of hospitalization and postoperative complications; as well as the function of the knee in the early stage after the operation, were recorded.

RESULTS

Ninety-one participants were included in the final analysis. At 3 months, the incidence of chronic pain was 30.4% in the ropivacaine group, significantly lower than 51.1% in the placebo group. Compared with the placebo group, the ACB + IPACK with ropivacaine group had significantly lower pain scores at 4 hours, 8 hours, 16 hours, and 24 hours after the operation; increased the knee range of motion at 8 hours and 24 hours after the operation; and a significantly decreased incidence of chronic pain at 3 months after the operation. During the follow-up period, there were no nerve block-related complications in either group.

CONCLUSION

In the context of multimodal analgesia protocols, ACB combined with IPACK before surgery decreases the incidence and intensity of chronic pain 3 months after TKA compared with placebo injection. In addition, it reduces the NRS scores, whether at rest or during mobilization, and improves knee function within 24 hours after TKA.

TRIAL REGISTRATION

This trial was registered in the China Clinical Trial Center (registration number ChiCTR2200065300) on November 1, 2022.

Uniportal video-assisted thoracic surgery versus open thoracotomy for chronic pain after surgery: a prospective cohort study

PURPOSE

The potential of uniportal video-assisted thoracic surgery (U-VATS) to reduce chronic pain after thoracic surgery (CPTS) compared to open thoracotomy (OT) remains unexplored. This prospective study aims to assess the incidence of CPTS following U-VATS or OT and identify associated risk factors.

METHODS

Patients undergoing thoracic surgery were recruited from March 2021 to March 2022, categorized by surgical approach (U-VATS vs. OT). Standard clinical protocols for surgery, anesthesia, and analgesia were followed. Pain symptoms were assessed using the Short-form McGill Pain Questionnaire, with follow-ups up to 6 months. Perioperative factors influencing CPTS at 3 months were analyzed through univariate and multivariate methods.

RESULTS

A total of 694 patients were analyzed. Acute pain after thoracic surgery (APTS) was significantly less severe in the U-VATS group (p < 0.001). U-VATS patients exhibited a lower incidence of CPTS at 3 months (63.4% vs. 80.1%, p < 0.001), with reduced severity among those experiencing CPTS (p = 0.007) and a decreased occurrence of neuropathic pain (p = 0.014). Multivariate analysis identified OT incision, moderate to severe APTS (excluding moderate static pain at 24 h postoperative), nocturnal surgery, and lung surgery as risk factors for CPTS.

CONCLUSION

This study underscores the potential of U-VATS to reduce both the incidence and severity of CPTS at 3 months compared to OT. Furthermore, it highlights risk factors for CPTS, including OT incision, inadequately managed APTS, lung surgery, and nocturnal surgery. These findings emphasize the importance of considering surgical approach and perioperative pain management strategies to mitigate the burden of CPTS.

Preoperative frailty predicts postoperative pain after total knee arthroplasty in older patients: a prospective observational study

PURPOSE

Frailty is reportedly associated with postoperative adverse outcomes and may increase the risk of post-surgical pain. Our study aimed to explore whether frailty was an independent risk factor for pain after total knee arthroplasty (TKA) in older patients.

METHODS

Included in this prospective observational study were patients aged 65 or older who underwent primary TKA. Frailty of the patients was assessed before surgery using the comprehensive geriatric assessment-frailty index and pain was evaluated before and after surgery using the Numerical Rating Scale.

RESULTS

Of the 164 patients including 125 females with a mean age of 71.4 ± 4.6 years, 51 patients were identified as being frail. Patients with chronic post-surgical pain had a significantly higher frailty index than those without chronic post-surgical pain, which was the same in patients with acute post-surgical pain. After adjusting for other confounding factors, frailty was shown to be an independent risk factor for both acute (OR: 13.23, 95% CI 3.73-46.93, P < 0.001) and chronic post-surgical pain (OR: 4.24, 95% CI 1.29-14.00, P = 0.02). The area under the receiver operating characteristic curve for frailty predicting chronic post-surgical pain was 0.73 (P < 0.001, 95% CI 0.65-0.81).

CONCLUSIONS

Our findings demonstrated that preoperative frailty in older patients was a predictor of acute and chronic post-surgical pain after TKA, suggesting that frailty assessment should become a necessary procedure before operations, especially in older patients.

The Impact of Acute Postoperative Pain in Developing Chronic Pain after Total Knee Arthroplasty

While total knee arthroplasties (TKAs) are performed with the intent to reduce pain, chronic postsurgical pain (CPSP) is one of the most well-documented complications that can occur following surgery. This study aimed to assess whether perioperative factors, focusing on acute postsurgical pain and perioperative opioid consumption, were associated with the development of chronic postsurgical pain. Under general anesthesia, 108 patients underwent TKA and were treated postoperatively with a multimodal analgesia approach. Numeric Rating Scale (NRS) pain scores at rest and with movement were recorded on postoperative days 0-3, 7, 14, and 30. Patients were sent a survey to assess chronic pain at months 22-66, which was examined as a single-group post hoc analysis. Based on the responses, patients were either classified into the CPSP or non-CPSP patient group. Chronic postsurgical pain was defined as an NRS score ≥ 4 with movement and the presence of resting pain. The primary outcome was a change in NRS. There were no differences in NRS pain scores with movement in the first 30 days postoperatively between patients with CPSP and without CPSP. Each unit increase in resting pain on postoperative days 3 and 14 was associated with significantly greater odds of CPSP presence (OR = 1.52; OR = 1.61, respectively), with a trend towards greater odds of CPSP at days 7 and 30 (OR = 1.33; OR = 1.43, respectively). We found that very intense pain in the initial phase seems to be related to the development of CPSP after TKA.

Low-intensity pulsed ultrasound phonophoresis with diclofenac alleviated inflammation and pain via downregulation of M1 macrophages in rats with carrageenan-induced knee joint arthritis

Objective

This study aimed to investigate the effects of low-intensity pulsed ultrasound (LIPUS) phonophoresis with diclofenac on inflammation and pain in the acute phase of carrageenan-induced arthritis in rats.

Design

60 male Wistar rats were randomly divided into the arthritis, diclofenac, LIPUS, phonophoresis, and sham-arthritis control groups. LIPUS and transdermal diclofenac gel were applied to the lateral side of the inflamed knee for 7 days, initiated postinjection day 1. In the phonophoresis group, diclofenac gel was rubbed onto the skin, followed by LIPUS application over the medication. Knee joint transverse diameters, pressure pain thresholds (PPTs), and paw withdrawal thresholds (PWT) were evaluated. The number of CD68-, CD11c-, and CD206-positive cells, and IL-1β and COX-2 mRNA expression were analyzed 8 days after injection.

Results

In the phonophoresis group, the transverse diameter, PPT, PWT significantly recovered at the day 8 compared to those in the LIPUS and diclofenac groups. The number of CD68- and CD11c-positive cells in the phonophoresis group was significantly lower than that in the LIPUS and diclofenac groups, but no significant differences were observed among three groups in CD206-positive cells. IL-1β and COX-2 mRNA levels were lower in the phonophoresis group than in the arthritis group, although there were no differences among the LIPUS, diclofenac, and phonophoresis groups.

Conclusion

LIPUS phonophoresis with diclofenac is more effective to ameliorate inflammation and pain compared to diclofenac or LIPUS alone, and the mechanism involves the decrease of M1 macrophages.

Construction and Validation of Machine Learning Algorithms to Predict Chronic Post-Surgical Pain Among Patients Undergoing Total Knee Arthroplasty

BACKGROUND

Chronic post-surgical pain (CPSP) is a common but undertreated condition with a high prevalence among patients undergoing total knee arthroplasty (TKA). An effective model for CPSP prediction has not been established yet.

AIMS

To construct and validate machine learning models for the early prediction of CPSP among patients undergoing TKA.

DESIGN

A prospective cohort study.

PARTICIPANTS/SUBJECTS

A total of 320 patients in the modeling group and 150 patients in the validation group were recruited from two independent hospitals between December 2021 and July 2022. They were followed up for 6 months to determine the outcomes of CPSP through telephone interviews.

METHODS

Four machine learning algorithms were developed through 10-fold cross-validation for five times. In the validation group, the discrimination and calibration of the machine learning algorithms were compared by the logistic regression model. The importance of the variables in the best model identified was ranked.

RESULTS

The incidence of CPSP in the modeling group was 25.3%, and that in the validation group was 27.6%. Compared with other models, the random forest model achieved the best performance with the highest C-statistic of 0.897 and the lowest Brier score of 0.119 in the validation group. The top three important factors for predicting CPSP were knee joint function, fear of movement, and pain at rest in the baseline.

CONCLUSIONS

The random forest model demonstrated good discrimination and calibration capacity for identifying patients undergoing TKA at high risk for CPSP. Clinical nurses would screen out high-risk patients for CPSP by using the risk factors identified in the random forest model, and efficiently distribute preventive strategy.

Prognostic factors for chronic post-surgical pain after lung and pleural surgery: a systematic review with meta-analysis, meta-regression and trial sequential analysis

Chronic post-surgical pain is known to be a common complication of thoracic surgery and has been associated with a lower quality of life, increased healthcare utilisation, substantial direct and indirect costs, and increased long-term use of opioids. This systematic review with meta-analysis aimed to identify and summarise the evidence of all prognostic factors for chronic post-surgical pain after lung and pleural surgery. Electronic databases were searched for retrospective and prospective observational studies as well as randomised controlled trials that included patients undergoing lung or pleural surgery and reported on prognostic factors for chronic post-surgical pain. We included 56 studies resulting in 45 identified prognostic factors, of which 16 were pooled with a meta-analysis. Prognostic factors that increased chronic post-surgical pain risk were as follows: higher postoperative pain intensity (day 1, 0-10 score), mean difference (95%CI) 1.29 (0.62-1.95), p < 0.001; pre-operative pain, odds ratio (95%CI) 2.86 (1.94-4.21), p < 0.001; and longer surgery duration (in minutes), mean difference (95%CI) 12.07 (4.99-19.16), p < 0.001. Prognostic factors that decreased chronic post-surgical pain risk were as follows: intercostal nerve block, odds ratio (95%CI) 0.76 (0.61-0.95) p = 0.018 and video-assisted thoracic surgery, 0.54 (0.43-0.66) p < 0.001. Trial sequential analysis was used to adjust for type 1 and type 2 errors of statistical analysis and confirmed adequate power for these prognostic factors. In contrast to other studies, we found that age had no significant effect on chronic post-surgical pain and there was not enough evidence to conclude on sex. Meta-regression did not reveal significant effects of any of the study covariates on the prognostic factors with a significant effect on chronic post-surgical pain. Expressed as grading of recommendations, assessment, development and evaluations criteria, the certainty of evidence was high for pre-operative pain and video-assisted thoracic surgery, moderate for intercostal nerve block and surgery duration and low for postoperative pain intensity. We thus identified actionable factors which can be addressed to attempt to reduce the risk of chronic post-surgical pain after lung surgery.

Persistent incisional pain at 1 year after craniotomy: a retrospective observational study

BACKGROUND

There have been few reports on persistent incisional pain at 1 year after craniotomy. Hence, this study aimed to explore the distribution of pain at 1 year after elective craniotomy and its related factors.

METHODS

This retrospective study included data prospectively collected to assess postoperative functional disability. We included patients aged > 55 years at the time of recruitment for our initial study and who had complete data regarding the pain numeric rating scale (NRS) score at 1 year post craniotomy. The primary outcome was the pain NRS score, which was assessed at the postanesthetic clinic as well as at 3 months and 1 year after craniotomy. Multivariable negative binomial regression analysis was performed to analyze the relationship between the pain NRS score at 1 postoperative year and 12 clinically meaningful covariates. These included the Short Form-8 scores for bodily pain and mental health, with higher scores indicating better health.

RESULTS

We analyzed data from 102 patients. The mean (95% confidence interval) pain NRS scores at the three measurement points were 2.8 (2.3-3.3), 1.2 (0.8-1.6), and 0.6 (0.3-0.8), respectively. Multivariable analysis revealed that preoperative bodily pain (risk ratio, 0.93; 95% confidence interval, 0.88-0.98) and the pain NRS score at the postanesthetic clinic (risk ratio, 1.32; 95% confidence interval, 1.14-1.52) were associated with the risk of persistent pain at 1 postoperative year.

CONCLUSIONS

The pain score at 1 year after elective craniotomy was minor; however, preoperative bodily pain and postoperative pain scores were significantly related factors.

Perioperative Analgesics and Anesthesia as Risk Factors for Postoperative Chronic Opioid Use in Patients Undergoing Total Knee Arthroplasty: A Retrospective Cohort Study Using Japanese Hospital Claims Data

BACKGROUND

Patients with chronic postsurgical pain are commonly prescribed opioids chronically because of refractory pain although chronic opioid use can cause various severe problems.

OBJECTIVE

We aimed to investigate postoperative chronic opioid use and its association with perioperative pain management in patients who underwent a total knee arthroplasty in a Japanese real-world clinical setting.

METHODS

We conducted a retrospective cohort study using an administrative claims database. We used a multivariate logistic regression analysis to examine the association between perioperative analgesic and anesthesia prescriptions and postoperative chronic opioid use. We calculated all-cause medication and medical costs for each patient.

RESULTS

Of the 23,537,431 patient records, 14,325 patients met the criteria and were included in the analyses. There were 5.4% of patients with postoperative chronic opioid use. Perioperative prescriptions of weak opioids, strong and weak opioids, and the α₂δ ligand were significantly associated with postoperative chronic opioid use (adjusted odds ratio [95% confidence interval], 7.22 [3.89, 13.41], 7.97 [5.07, 12.50], and 1.45 [1.13, 1.88], respectively). Perioperative combined prescriptions of general and local anesthesia were also significantly associated with postoperative chronic opioid use (3.37 [2.23, 5.08]). These medications and local anesthesia were more commonly prescribed on the day following surgery, after routinely used medications and general anesthesia were prescribed. The median total direct costs were approximately 1.3-fold higher among patients with postoperative chronic opioid use than those without postoperative chronic opioid use.

CONCLUSIONS

Patients who require supplementary prescription of analgesics for acute postsurgical pain are at high risk of postoperative chronic opioid use and these prescriptions should be given careful consideration to mitigate the patient burden.

Radiofrequency Ablation of the Infrapatellar Branch of the Saphenous Nerve for the Treatment of Chronic Anterior Inferomedial Knee Pain

INTRO

Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment for chronic knee pain related to osteoarthritis. It is often utilized when conservative management has failed and patients wish to avoid arthroplasty, are poor surgical candidates due to comorbid medical conditions, or in those suffering from persistent pain after arthroplasty. The classic targets for GNRFA include the superior lateral genicular nerve, superior medial genicular nerve, and inferior medial genicular nerve but multiple anatomic studies have demonstrated additional sensory innervation to the knee.

OBJECTIVE

In this research article, we propose an image-guided technique that can safely target the infrapatellar branch of the saphenous nerve which also provides sensory innervation to the anterior capsule.

PROPOSAL

The proposed technique includes variations for conventional bipolar radiofrequency ablation, cooled radiofrequency ablation, dual-tined bipolar radiofrequency ablation, and monopolar radiofrequency ablation using a long axis approach. The described technique is based on updated anatomic studies and takes into account safety concerns such as thermal risk to the skin and/or pes anserine tendons and breaching of the synovial cavity.

CONCLUSION

Future clinical research should be performed to confirm the safety and effectiveness of this specific approach.

Persistent postoperative pain at 1 year after orthopedic surgery and its association with functional disability

PURPOSE

Orthopedic hip, knee, and spinal surgeries have a relatively high incidence of persistent postoperative pain, with the highest risk observed in Asian ethnicity. This study aimed to investigate the distribution of persistent pain at 1 year after surgery and its associated factors and effects on functional disability.

METHODS

This secondary analysis of a prospective observational study included 297 patients aged ≥ 55 years who underwent elective total hip arthroplasty, total knee arthroplasty, and spine and spinal cord surgeries under general anesthesia. Data were collected perioperatively and at 3 months and 1 year postoperatively to assess persistent postoperative pain on a numerical rating scale.

RESULTS

At 1 year postoperatively, 34.6% (103/297) of patients reported pain, with a score of ≥ 1 and a mean score of 1.2. Multivariable negative binomial regression analysis revealed that less preoperative bodily pain (risk ratio [RR], 0.97; 95% confidence interval [CI] 0.94-0.99), preoperative C-reactive protein (CRP) level (RR, 1.19; 95% CI 1.01-1.39), and spine and spinal cord surgeries (RR, 2.48; 95% CI 1.30-4.75) increased the risk of persistent pain at 1 year after surgery, which was a significant factor for predicting the 12-item World Health Organization Disability Assessment Schedule 2.0 score (p < 0.001).

CONCLUSION

The mean score for persistent pain at 1 year after surgery on the numerical rating scale was 1.2. Worse preoperative bodily pain, higher preoperative serum CRP level, and spine and spinal cord surgeries increased the persistent pain score at 1 year after surgery, which was associated with functional disability CLINICAL TRIAL REGISTRATION: This prospective observational study was registered on the University Hospital Medical Information Network (31 December 2015; UMIN000021671).

Prevalence and Predictors of Chronic Pain with Two-Year Follow-Up After Knee Arthroplasty

Background

Pain relief is the most important issue in the long-term outcome of arthroplasty surgery, with nearly one-third of patients still suffered persistent pain and caused dissatisfaction after the surgery.

Methods

A total of 713 patients underwent primary elective primary TKA and UKA were included consecutively between July 2018 and December 2019, using binary logistic method to analyze the data.

Results

The prevalence of CPSP at rest and on movement at 2-year was 12.1% and 37.7% respectively after primary knee arthroplasty and CPSP at rest factors included: age above 80 (odds ratio [OR]= 6.72, 95% confidence interval [CI] 1.58 to 28.56), BMI above 30 (2.339, 1.02 to 5.383), and moderate to severe pain variables: preoperative pain, (1.95, 1.11 to 3.41); APSP on movement, 4.9 (2.31–10.6); and follow-up contralateral knee pain-at-rest scores (12.6, 5.5 to 28.5). Factors associated with presence of CPSP on movement included: no smoking (2.59, 1.07 to 6.26); and moderate to severe pain variables: preoperative pain, (1.57, 1.073 to 2.30); APSP at rest, (1.85, 1.13 to 3.02); APSP on movement, 6.11 (3.82 to 9.78); and follow-up contralateral knee pain-on-movement scores, 3.22 (2.08 to 5.00). Factors to occurrence of moderate to severe CPSP on movement include: presence of COPD (12.20, 2.19 to 67.98); and moderate to severe pain variables: preoperative pain (2.36, 1.32 to 4.23); APSP on movement (4.68, 1.95 to 11.25); and follow-up contralateral knee pain-on-movement scores (2.71, 1.66 to 4.42).

Conclusion

Prevention strategies should be targeted to different types of pain, and the comorbidity of COPD undergoing knee arthroplasty should receive early identification and attention.

Predictors of Chronic Postsurgical Pain in Elderly Patients Undergoing Hip Arthroplasty: A Multi-Center Retrospective Cohort Study

Background

Identifying patients at high risk of developing chronic postsurgical pain (CPSP) is of extreme importance in order to help launch appropriate therapeutic strategies and intensive initiation of pain management.

Aim

In this study, we aimed to conduct a multi-center retrospective cohort study to establish a prognostic model and a nomogram to predict the risks of CPSP in elderly patients who underwent hip arthroplasty at 6 months postoperatively.

Methods

We collected data from 736 patients aged >65 years who had undergone hip arthroplasty from October 1, 2016 to September, 30, 2018 at multiple tertiary referral centers in Guangzhou, China. All data were randomly stratified into a training set and a testing set at a ratio of 8:2. Data were analyzed via multiple logistic regression analysis with receiver operating characteristic (ROC) curves and areas under the curve. This model was further validated by estimating calibration and discrimination. A nomogram was ultimately developed.

Results

A total of 736 eligible patients were enrolled, 27.20% of whom developed CPSP within 6 months postoperatively. Preoperative pain in the surgical area (OR=2.456, 95% CI:1.814–3.327, P<0.001), preoperative depression state (OR=1.256, 95% CI:1.146–1.378, P<0.001), surgical type (OR=7.138, 95% CI:3.548–14.364, P<0.001), acute postoperative numerical rating scale score (OR=5.537, 95% CI:3.607–8.499, P<0.001) and analgesic type (patient-controlled epidural analgesia: OR=0.129, 95% CI:0.055–0.299, P<0.001; patient-controlled intravenous analgesia: OR=0.033, 95% CI:0.011–0.097, P<0.001) were identified as independent significant factors associated with CPSP. A prognostic model was established and further validated. An ROC curve confirmed the predictive ability of this model with a high sensitivity value of 92.12% (95% CI:86.90–95.74) and specificity value of 91.72% (95% CI:88.77–94.11). A nomogram was developed to simplify the use of the predictive model in clinical practice.

Conclusion

This prognostic model could be of great value in clinical practice, serving as the basis for early personalized analgesic management of elderly patients undergoing hip arthroplasty.

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Oral administration of prednisone effectively reduces subacute pain after total knee arthroplasty

INTRODUCTION

Controlling the pain after TKA has always been our research focus. Dexamethasone has a significant effect in controlling acute pain following TKA. We hypothesis oral administration of prednisone could alleviate post-TKA subacute pain.

METHODS

This was a prospective, randomized controlled trial dividing patients into prednisone group and control group. Routine analgesic regimens included injection of cocktail mixture intraoperatively, oral celecoxib and tramadol postoperatively. Patients in prednisone group received oral administration of prednisone (10mg, qd, from the first day postoperatively, for 2 weeks). VAS was applied for evaluating pain with ambulation (PWA) and pain at rest (PAR). Follow-up was performed for about three months. The primary end-points were PWA and PAR; secondary end-points were postoperative daily celecoxib use and tramadol use.

RESULTS

A total of 49 patients were enrolled in prednisone group and control group, respectively. VAS of PWA was lower in prednisone group on the 7^th, 14^th and 28^th (p=0.05) day after TKA than that in the control group. Meanwhile, VAS of PAR was lower in prednisone group on the postoperative 14^th and 28^th day (p=0.05) than that in the control group.

CONCLUSIONS

Continuous oral administration of 10mg prednisone for 14 days after TKA effectively alleviates subacute pain (including PWA and PAR) and reduces postoperative consumption of analgesics.

LEVEL OF EVIDENCE

II; low power randomized trial.

Chronic postsurgical pain after total knee arthroplasty: A prospective cohort study in Japanese population

OBJECTIVES

To elucidate the prevalence and risk factors of chronic postsurgical pain (CPSP) after primary total knee arthroplasty (TKA) in Japanese population.

METHODS

Consecutive patients undergoing primary TKA in a Japanese tertiary hospital (211 knees) were assessed. CPSP after TKA was defined as moderate to severe pain (VAS >30 mm), either at rest or during walking, one year after surgery. Clinical and radiographic data were compared between CPSP and non-CPSP groups and multivariate logistic regression was used to identify predictors of CPSP.

RESULTS

The prevalence of CPSP was 8.8%. CPSP group showed significantly higher preoperative WOMAC subscales (pain, function and stiffness), higher rate of postoperative coronal malalignment (femorotibial angle >178° or <170°) and larger varus angle of tibial component compared with non-CPSP group. Logistic regression analysis revealed that preoperative higher WOMAC pain and postoperative coronal malalignment were independent risk factors of CPSP. In a subgroup analysis of patients with well-aligned TKA, preoperative pain VAS at rest was the only risk factor of CPSP.

CONCLUSION

Preoperative severe pain and postoperative coronal malalignment were independent risk factors of CPSP after TKA. Preoperative pain management in patients with severe pain and good coronal alignment after TKA possibly minimize the development of CPSP.

Factors Affecting Persistent Postoperative Pain in Patients with Hip Fractures

Osteoporotic fractures are common among older people, and hip fractures (HF) can be devastating. Surgery is indicated for most cases of HF, and chronic persistent postoperative pain is likely to occur. This study investigated the multifaceted factors related to persistent pain occurring during the acute phase and subacute phase of recovery after HF surgery. We conducted a prospective 8-week study of older HF patients after surgery. We evaluated pain intensity, depression symptoms, the fear of falling, pain catastrophizing, cognition and attention, the ability to perform activities of daily living, and the physical performance at 2 weeks (acute phase) and at 4 weeks (subacute phase) after surgery. Patients were divided into the light group (Verbal Rating Scale (VRS) score ≤1) and severe group (VRS score ≥2) according to pain intensity at 8 weeks (recovery phase) after surgery. Factors affecting persistent postoperative pain during recovery were examined using logistic regression analysis. Seventy-two patients were analyzed: 50 in the light group and 22 in the severe group. In the severe group, pain with movement and Pain Catastrophizing Scale scores were higher than those of the light group at 2 weeks and at 4 weeks after surgery. The regression analysis showed that pain with movement at 2 weeks and at 4 weeks after surgery and pain catastrophizing at 4 weeks after surgery were related to persistent postoperative pain. HF patients may have persistent pain if they continue to experience pain and catastrophize their pain during the acute phase and subacute phase after surgery.

Long-term incidence of chronic postsurgical pain after thoracic surgery for lung cancer: a 10-year single-center retrospective study

BACKGROUND

The long-term incidence of chronic postsurgical pain (CPSP) after thoracic surgery has not yet been reported.

METHODS

We retrospectively reviewed the electronic medical records of 4218 consecutive patients who underwent thoracic surgery for lung cancer between 2007 and 2016. We evaluated the long-term incidence of CPSP after thoracic surgery at intervals of 3 months for 36 months. A Cox proportional hazard regression analysis was performed to investigate the predictors of CPSP after thoracic surgery.

RESULTS

A total of 3200 patients were included in the analysis. Of these, 459 (14.3%) and 558 (17.4%) patients were diagnosed with CPSP within 3 and 36 months after surgery, respectively. Furthermore, the incidence of CPSP decreased over time. Additionally, 99 (3.1%) patients were newly diagnosed with CPSP at least 6 months after surgery. Female sex (HR 1.20, 95% CI 1.00 to 1.43; p=0.04), longer duration of surgery (HR 1.11, 95% CI 1.03 to 1.20; p<0.01), higher 11-point Numeric Rating Scale score at first outpatient visit after surgery (HR 1.29, 95% CI 1.24 to 1.34; p<0.001), postoperative chemotherapy (HR 1.55, 95% CI 1.26 to 1.90; p<0.001), and postoperative radiation therapy (HR 1.35, 95% CI 1.05 to 1.74; p=0.02) were significant predictors of CPSP for 36 months after surgery.

CONCLUSION

Our study showed a decreasing trend in the incidence of CPSP as well as delayed-onset or recurrent CPSP after thoracic surgery. A better understanding of the progression of CPSP after thoracic surgery may provide important information on its prediction and treatment.

Effects of the nontourniquet combined with controlled hypotension technique on pain and long-term prognosis in elderly patients after total knee arthroplasty: a randomized controlled study

PURPOSE

The aim of this study was to confirm the alleviating effects of the nontourniquet technique on the postoperative acute and chronic pain of patients after total knee arthroplasty (TKA).

METHODS

122 elderly patients undergoing TKA were randomly divided into two groups: group T (n = 58) and group H (n = 64). An electronic inflatable tourniquet was used during TKA in group T. The patients in group H received controlled hypotension but without tourniquet use during the operation. The numeric rating scale (NRS) score was used to evaluate pain level on day 1, day 2, day 3 and day 7 after the operation, and the incidence of chronic pain was judged at 3-month and 1-year follow-ups, and functional recovery of the knee joint was estimated by the active range of knee joint motion (AROM) at the same time points. Cognitive function was assessed by the montreal cognitive assessment scale (MoCA) for 7 days after operation.

RESULTS

There were no significant differences in the NRS scores and AROM for 7 days after surgery. The incidence rate of chronic pain in group H (25.0%) was lower than that in group T (41.4%) and the AROM in group H was greater at one year follow-up. The MoCA score in group H was lower than that in group T on day 1 and day 2.

CONCLUSION

The nontourniquet combined with controlled hypotension technique can alleviate chronic pain and promote the long-term rehabilitation of patients after TKA.

Roles of inflammation, neurogenic inflammation, and neuroinflammation in pain

Inflammation is the body's response to injury and infection, involving a complex biological response of the somatosensory, immune, autonomic, and vascular systems. Inflammatory mediators such as prostaglandin, proinflammatory cytokines, and chemokines induce pain via direct activation of nociceptors, the primary sensory neurons that detect noxious stimuli. Neurogenic inflammation is triggered by nerve activation and results in neuropeptide release and rapid plasma extravasation and edema, contributing to pain conditions such as headache. Neuroinflammation is a localized inflammation in the peripheral nervous system (PNS) and central nervous system (CNS). A characteristic feature of neuroinflammation is the activation of glial cells in dorsal root ganglia, spinal cord, and brain which leads to the production of proinflammatory cytokines and chemokines in the PNS and CNS that drives peripheral sensitization and central sensitization. Here, we discuss the distinct roles of inflammation, neurogenic inflammation, and neuroinflammation in the regulation of different types of pain conditions, with a special focus on neuroinflammation in postoperative pain and opioid-induced hyperalgesia.

Classification of acute pain trajectory after breast cancer surgery identifies patients at risk for persistent pain: a prospective observational study

Purpose

Predictive value and accuracy of the acute pain trajectory were compared with those of pain intensity at 1 day after the surgery for pain prevalence at 6 months after the surgery.

Materials and methods

Female patients scheduled for breast cancer surgery were eligible for this study. Patients were questioned about pain intensity daily during the 7 days after surgery. Presence of pain, its location, and intensity as well as the Japanese version of the quality of the recovery-40 (QOR-40) were determined in an interview prior to and at 6 months after the surgery. Acute pain trajectory was determined by a group-based trajectory modeling analysis that was based on the pain intensity at 1–7 days after surgery. Predictive value of the acute pain trajectory for the presence of pain at 6 months after the surgery was assessed by a logistic regression model. The predictive value was compared with pain intensity at 1 day after the surgery.

Results

A total of 123 participants completed the 6-month follow-up. The three-cluster model (mild, moderate, and severe pain) was considered to be the most statistically appropriate model for the acute pain trajectory. After 6 months, 51.2% and 8.9% of participants reported pain and severe pain, respectively. Presence of pain at 6 months after the surgery was associated with poor recovery. The severe pain cluster was significantly associated with the presence of pain at 6 months after the surgery (adjusted odds ratio, 9.40; P<0.001 vs mild pain cluster).

Conclusion

Classification of patients according to the acute pain trajectory, when compared with the classification according to pain intensity at 1 day after the surgery, made it possible to predict with better precision those patients who will develop persistent postsurgical pain.

Chronic pain after total knee arthroplasty

Despite a good outcome for many patients, approximately 20% of patients experience chronic pain after total knee arthroplasty (TKA).

Chronic pain after TKA can affect all dimensions of health-related quality of life, and is associated with functional limitations, pain-related distress, depression, poorer general health and social isolation.

In both clinical and research settings, the approach to assessing chronic pain after TKA needs to be in-depth and multidimensional to understand the characteristics and impact of this pain. Assessment of this pain has been inadequate in the past, but there are encouraging trends for increased use of validated patient-reported outcome measures.

Risk factors for chronic pain after TKA can be considered as those present before surgery, intraoperatively or in the acute postoperative period. Knowledge of risk factors is important to guide the development of interventions and to help to target care. Evaluations of preoperative interventions which optimize pain management and general health around the time of surgery are needed.

The causes of chronic pain after TKA are not yet fully understood, although research interest is growing and it is evident that this pain has a multifactorial aetiology, with a wide range of possible biological, surgical and psychosocial factors that can influence pain outcomes.

Treatment of chronic pain after TKA is challenging, and evaluation of combined treatments and individually targeted treatments matched to patient characteristics is advocated. To ensure that optimal care is provided to patients, the clinical- and cost-effectiveness of multidisciplinary and individualized interventions should be evaluated.

Cite this article: EFORT Open Rev 2018;3:461-470. DOI: 10.1302/2058-5241.3.180004