Prevalence and Risk Factors for Postsurgical Pain After the Open Reduction and Internal Fixation of Lower Limbs.

Study Overview
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Brief Summary
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The objective of this study is to specify the demographic and medical factors that most likely constitute a risk of developing CPSP in the patients with lower limb.

Detailed Description
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Chronic pain,one of the most frequent causes for patients to seek medical care,is a recognized health problem.Chronic postsurgical pain (CPSP), commonly defined as pain that develops after a surgical procedure and persists at least 3 months, constitutes a widely underdiagnosed and often poorly treated medical problem affecting 10-50% of all postsurgical patients. According to the reports,in the United States alone,1.9 million persons abused or were dependent on prescription opioid analgesics for chronic pain in 2013,contributing to one of the worst public health crises the developed world has recently faced.Here,open reduction and internal fixation（ORIF） of lower limb fractures ,what the investigators focus, is a common surgical procedure in orthopedics and microscopic hand and foot surgery.The removal of the intramedullary nail can relieve anterior knee pain, but in a substantial number of patients, pain persists after nail removal.The most painful daily activities are kneeling and squatting.Therefore, it is increasingly important and urgent to solve the postoperative chronic pain of patients with lower extremity fractures surgery. The underlying biology of chronic postoperative pain and genetic heritability is complex and not yet fully understood . A common feature of CPSP is that the painful sensations change from the familiar acute postoperative pain to a complex pain syndrome with nonaplastic characteristics，neuropathic characteristics, or both. Preclinical studies have revealed that neuroinflammation is one of pathological hallmarks of CPSP. The transition from acute to chronic pain starts early within the first 2 weeks after nonaplastic by peripheral and central inflammatory processes and activation of spinal glial cells.Repetitive nociception resulting from prolonged inflammatory and neuropathic responses to noxious stimuli causes a cascade of biochemical and structural changes to various pain pathways resulting in sensitization of the peripheral and central nervous system（CNS）. Cytokines and neurotrophic factors have been identified as pivotal mediators involved in neuroimmune activation pathways and cascades in various preclinical chronic pain models. Although lower limb fracture is one of the most frequently reported triggering CPSP events, few large-scale studies have shown the occurrence of and factors associated with it.The objectives of investigators are to specify the demographic and medical factors that most likely constitute a risk of developing CPSP and to search for potential interventions to reduce the occurrence of CPSP in these limb fracture patients.

Official Title
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A Prospective Cohort Survey on Prevalence and Risk Factors for Persistent Postsurgical Pain After the Open Reduction and Internal Fixation of the Lower Limbs

Conditions
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Chronic Post Operative Pain

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Underwent surgical repair including fracture of the lower leg, fracture of the foot and fractures involving multiple regions of the lower limbs. Exclusion Criteria: Refusing to participate in this study.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Pain-free control subjects<br>Patients with no postoperative chronic pain after open reduction and internal fixation of lower limb fractures. | |
| Patients with chronic postsurgical pain<br>Patients with postsurgical chronic pain after open reduction and internal fixation of lower limb fractures. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative chronic pain：pain score | Postoperative chronic pain assessed by the Numerical Rating Scale (NRS). Pain score >=3 at operational areas (minimum 0, maximum 10, higher score indicates greater pain). Pain developed after a surgical procedure or increased in intensity after the surgical procedure. Pain should be of at least 3 months duration with a significant negative effect on the quality of life. Pain is a continuation of acute postoperative pain or may develop after an asymptomatic period and pain is localized to the surgical field or to a referred area (eg, innervation territory, referred dermatome for visceral surgery). Other possible causes for the pain have been excluded (eg, infection, cancer recurrence) | Through study completion, an average of 1 year | 
| Perioperative inflammatory state | The inflammatory factors，C-reactive protein（CRP）, white blood cell count, and lymphocyte ratio of the subjects were counted. | Up to 10 days | 
| Lifestyle and behaviour of the subjects | Through the electronic medical record system and telephone follow-up, to understand whether there is a history of smoking, drinking, physical activity. | Baseline | 
| Preoperative complications of the participants | Including cardiovascular and cerebrovascular diseases (such as hypertension, coronary heart disease), respiratory diseases (such as chronic obstructive pulmonary disease), endocrine system diseases (such as diabetes, hyperthyroidism) and so on. | Baseline | 
| Medical interventions history | The use of the analgesic drugs， including the past and this perioperative period | Up to 10 days | 
| Surgery details | Including specific surgical site (femur, tibia or fibula or multiple injuries) ，the time of operation, the amount of bleeding during operation，etc. | Baseline | 
| Anesthesia during surgery | The types of anesthesia (general anesthesia, spinal anesthesia and whether to use nerve block, etc. ) | Baseline | 
| Age | The age of each subject in the operating room was counted. | Baseline | 
| Body mass index (BMI) | The BMI of each subject in the operating room was counted and compared. | Baseline | 
| Gender | The gender ratio of the CPSP group and pain-free group was recorded and compared. | Baseline | 
| Cultural background | Record the highest academic qualifications of the subjects. | Baseline |