This edition of the Cochrane Corner looks at the three reviews that were published in the second half of 2023: surgical versus non-surgical interventions for displaced intra-articular calcaneal fractures; cryotherapy following total knee arthroplasty; and physical activity and education about physical activity for chronic musculoskeletal pain in children and adolescents

In the UK and USA in 2016 more than 263,000 primary knee replacements were performed. Around 20% of patients report chronic post-surgical pain (CPSP) at three or more months after total knee replacement (TKR). A large proportion of adults with all types of chronic musculoskeletal pain do not use services for a number of reasons, despite being in constant or daily pain. Given the high prevalence of CPSP, there is potentially a large hidden population with an unexpressed need for care, experiencing ongoing pain and disability; understanding why they do not use health services may herald further insight into why many remain dissatisfied with knee replacement surgery. The aim of this study is to understand why some people with CPSP after TKR do not access services or make little use of healthcare. We conducted face-to-face in-depth interviews with 34 patients from 2 high-volume orthopaedic hospitals in England, to investigate their experience of long-term pain after knee replacement; their knowledge and understanding of CPSP; and their decisions about consulting for CPSP. The sample size was based on achievement of saturation and participants provided written informed consent. Interviews were transcribed and analysed using an inductive thematic approach with double coding for rigor. Ethical approval for the study was granted by the West Midlands Solihull Research Ethics Committee (15/WM/0469). A core theme within the analysis suggests that participants do not seek healthcare because they believe that nothing further can be done, either by themselves or by healthcare professionals. Surgeons' satisfaction with the knee surgery and reassurances that pain would improve, left patients feeling uncertain about whether to re-consult, and some assumed that further consultation could lead to further surgery or medication, which they wish to avoid. Some participants' comorbidities took precedence over their knee pain when seeking healthcare. Others felt they had received their “share” of healthcare resources and that others were more deserving of treatment. People's descriptions of pain varied, from dull, or aching to shooting pains. Many described their pain as “discomfort” rather than pain. The majority described pain that was better than their pre-surgical pain, though others described pain that was worse, which they believed to be nerve damage. Many expressed disappointment in the outcome of their TKR. Expectations of pain varied, where most had expected some post-surgical pain, others underestimated it, and some had expected to be completely pain free following their TKR. Our analysis suggests that the reasons that some people with CPSP after TKR do not consult are varied and complex, spanning psychosocial, structural, moral, and organisational domains. There was an overriding sense that further consultation would be futile or may lead to unwanted treatment. Results suggest that improved information for patients about CPSP and appropriate post-surgical healthcare services may help patients and clinicians to manage this condition more effectively

Summary Statement. The peripheral neuronal phenotype is significantly altered in rotator cuff tendinopathy (RCT) with a clear upregulation of the Glutaminergic system being present in disease. Introduction. Shoulder pain is the third most frequent cause of chronic musculoskeletal pain in the community and is usually caused by rotator cuff tendinopathy (RCT). The central and peripheral nervous system play an important role in both tissue homoeostasis and tendon healing. The Glutaminergic system is of key importance in driving the peripheral and central neuronal changes which increase the body's sensitivity to pain (1, 2). No study to date has investigated the role of the glutaminergic system in human RCT. We hypothesised that the peripheral neuronal phenotype would be altered in RCT, and would vary according to disease stage as measured by size of tear. The term ‘peripheral neuronal phenotype’ is used to refer to refer to specific characteristics of the peripheral nervous system, neuronal mediators and the receptors for these mediators in peripheral tissue. Methods. Rotator cuff tendon specimens were obtained from 64 patients undergoing the surgical repair of rotator cuff tears. Control supraspinatus tendon was obtained from 10 patients undergoing surgery for anterior instability using an ultrasound guided biopsy technique. Patients with rotator cuff tears were divided into 2 groups: the small/medium group (≤ 3cm size) and the large/massive group (>3cm size). The tendon tissue was histologically stained using Haematoxylin and Eosin, and immunohistochemically stained with primary antibodies visualised using 3, 3′-diaminobenzidine (DAB). Image analysis was performed blindly by 2 observers using Image-J to quantify the amount of DAB positive staining. Data was non-parametric in distribution and Mann-Whitney U tests were carried out using SPSS with significance levels set at a minimum of p<0.025. Results. There were significant changes in the peripheral neuronal phenotype in RCT. The Glutaminergic system was significantly up-regulated with an increase in Glutamate and changes in several related receptors in disease versus control (p<0.01). The standard deviation in nuclei count and mean cell nuclear area were both increased in disease (p<0.01) compared to controls. Tendon vascularity and cell proliferation were reduced in disease vs control (p<0.01). There were no significant correlations between pain scores and the peripheral tissue markers. Discussion/Conclusion. The peripheral neuronal phenotype is significantly altered in rotator cuff tendinopathy (RCT) with clear changes in the Glutaminergic system in disease. These findings are novel and improve our understanding of pain and tissue healing in RCT, potentially providing novel therapeutic targets