The association between knee temperature and pain in elders with osteoarthritis of the knee: a pilot study

Increases in local skin temperature correlate with spontaneous foot lifting and heat hyperalgesia in both incisional inflammatory models of pain

Background

This study investigated if a localized increase in skin temperature in rat models of incisional and inflammatory pain correlates with the intensity of spontaneous and evoked pain behaviors.

Methods

Anesthetized rats received either a 20-mm longitudinal incision made through the skin, fascia, and muscle of the plantar hind paw or an injection of complete Freund adjuvant into the plantar hind paw of anesthetized rats to induce local inflammation. Spontaneous and evoked pain behaviors were assessed, and changes in skin temperature were measured using a noncontact infrared thermometer.

Results

There were no differences in skin temperature between the ipsilateral and contralateral hind paw before the incision or inflammation. Skin temperature increased at 2 hours after hind paw plantar incision or 1 day after inflammation of the affected paw, which gradually returned to baseline by the first day and fourth days after treatment, respectively. The increase in skin temperature correlated with the intensity of spontaneous pain behaviors and heat but not with mechanical allodynia.

Conclusions

Our results suggest that a simple measurement of localized skin temperature using a noncontact infrared thermometer could measure the extent of spontaneous pain behaviors and heat hyperalgesia following plantar incision or inflammation in animals. In the absence of a reliable objective marker of pain, these results are encouraging. However, studies are warranted to validate our results using analgesics and pain-relieving interventions, such as nerve block on skin temperature changes.

Research progress of bone-targeted drug delivery system on metastatic bone tumors

Bone metastases are common in malignant tumors and the effect of conventional treatment is limited. How to effectively inhibit tumor bone metastasis and deliver the drug to the bone has become an urgent issue to be solved. While bone targeting drug delivery systems have obvious advantages in the treatment of bone tumors. The research on bone-targeted anti-tumor therapy has made significant progress in recent years. We introduced the related tumor pathways of bone metastases. The tumor microenvironment plays an important role in metastatic bone tumors. We introduce a drug-loading systems based on different environment-responsive nanocomposites for anti-tumor and anti-metastatic research. According to the process of bone metastases and the structure of bone tissue, we summarized the information on bone-targeting molecules. Bisphosphate has become the first choice of bone-targeted drug delivery carrier because of its affinity with hydroxyapatite in bone. Therefore, we sought to summarize the bone-targeting molecule of bisphosphate to identify the modification effect on bone-targeting. And this paper discusses the relationship between bisphosphate bone targeting molecular structure and drug delivery carriers, to provide some new ideas for the research and development of bone-targeting drug delivery carriers. Targeted therapy will make a more outstanding contribution to the treatment of tumors.

Stimuli-Sensitive Nanotherapies for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common chronic inflammatory disease in the joints. It is one of the leading causes of disability with increasing morbidity, which has become one of the serious clinical issues. Current treatments would only provide temporary relief due to the lack of early diagnosis and effective therapy, and thus the replacement of joints may be needed when the OA deteriorates. Although the intra-articular injection and oral administration of drugs are helpful for OA treatment, they are suffering from systemic toxicity, short retention time in joint, and insufficient bioavailability. Nanomedicine is potential to improve the drug delivery efficiency and targeting ability. In this focused progress review, the particle-based drug loading systems that can achieve targeted and triggered release are summarized. Stimuli-responsive nanocarriers that are sensitive to endogenous microenvironmental signals such as reactive oxygen species, enzymes, pH, and temperature, as well as external stimuli such as light for OA therapy are introduced in this review. Furthermore, the nanocarriers associated with targeted therapy and imaging for OA treatment are summarized. The potential applications of nanotherapies for OA treatment are finally discussed.

Discordance between radiographic findings, pain, and superficial temperature in knee osteoarthritis

Introduction

Knee pain is an imprecise marker of radiographic evidence of osteoarthritis (OA). These patients are more likely to develop central sensitisation to pain, a risk factor for chronic pain.

Objectives

The aim of this study was to examine the associations among radiographic evidence of OA, self-reported pain, pressure pain thresholds (PPT), and superficial knee temperature in individuals with knee OA.

Material and methods

This cross-sectional study enrolled 25 patients with knee OA with clinic and radiographic diagnosis of bilateral OA (Kellgren-Lawrence grading scale 1–4 in X-ray images), but symptoms of pain and discomfort in only one of the knees, with pain perception in the symptomatic knee equal to or above 4 in a visual analogue scale. Volunteers underwent an evaluation including demographic data, superficial knee temperature (infrared thermography, mean superficial temperature of the region of the knee) and PPT (digital algometry at longus adductor, vastus lateralis, vastus medialis and tibialis anterior muscles, patellar tendon, and centre of the patella).

Results

Comparisons between symptomatic and asymptomatic knees revealed no differences regarding Kellgren-Lawrence classification, knee superficial temperature, or PPT. Significant weak and moderate associations were found between radiographic classification of OA and PPT of both knees in almost all sites evaluated. Nonetheless, superficial temperature of the knee was not associated with PPT or Kellgren-Lawrence grading scale.

Conclusions

Patients with bilateral knee OA presented no differences in symptomatic and asymptomatic knees regarding radiographic evidence, knee temperature, and PPT, indicating that central sensitisation may be present in them. Radiographic classification of OA was significantly associated with PPT in both knees.

Cutaneous temperature and pressure pain threshold in individuals with knee osteoarthritis

Introduction

Osteoarthritis is a common disease in which skin temperature may be included among the pathophysiological factors. Thermography allows the mapping of cutaneous temperature and may be employed in the investigation of osteoarthritis.

Objectives

To evaluate cutaneous temperature of the lower limbs, as well as to verify its association with pressure pain thresholds in individuals with knee osteoarthritis.

Material and methods

This case series study was conducted with individuals of both genders aged 48–77 years with unilateral knee osteoarthritis. Volunteers underwent thermographic evaluation by an infrared sensor (FLIR T650SC). The anterior region of the thigh and leg and the knee area were evaluated. Pressure pain thresholds (PPT) were evaluated by algometry (Pain Diagnostics, Great Neck, USA) at the vastus medialis, vastus lateralis, rectus femoris, and patellar tendon. Data analysis was conducted with the statistical package SPSS v.24 for Windows. Comparisons between affected and unaffected sides were made by paired Student’s t-test or the Mann-Whitney U test, and associations between variables were assessed by Pearson or Spearman’s correlation coefficient. In all cases, the significance level was set at p ≤ 0.05.

Results

Eleven volunteers (63.1 ±9.5 years) participated in this study. When comparing cutaneous temperature, only the region of the knee showed a significant difference between sides (p = 0.02). There were no differences between affected and unaffected knees regarding pain tolerance (PPT) at all sites evaluated. There were also no significant associations between the study variables.

Conclusions

Individuals with knee osteoarthritis presented a higher temperature of the affected knee, but this was not associated with pressure pain thresholds.

Bioactive factors for cartilage repair and regeneration: Improving delivery, retention, and activity

Articular cartilage is a remarkable tissue whose sophisticated composition and architecture allow it to withstand complex stresses within the joint. Once injured, cartilage lacks the capacity to self-repair, and injuries often progress to joint wide osteoarthritis (OA) resulting in debilitating pain and loss of mobility. Current palliative and surgical management provides short-term symptom relief, but almost always progresses to further deterioration in the long term. A number of bioactive factors, including drugs, corticosteroids, and growth factors, have been utilized in the clinic, in clinical trials, or in emerging research studies to alleviate the inflamed joint environment or to promote new cartilage tissue formation. However, these therapies remain limited in their duration and effectiveness. For this reason, current efforts are focused on improving the localization, retention, and activity of these bioactive factors. The purpose of this review is to highlight recent advances in drug delivery for the treatment of damaged or degenerated cartilage. First, we summarize material and modification techniques to improve the delivery of these factors to damaged tissue and enhance their retention and action within the joint environment. Second, we discuss recent studies using novel methods to promote new cartilage formation via biofactor delivery, that have potential for improving future long-term clinical outcomes. Lastly, we review the emerging field of orthobiologics, using delivered and endogenous cells as drug-delivering "factories" to preserve and restore joint health. Enhancing drug delivery systems can improve both restorative and regenerative treatments for damaged cartilage. STATEMENT OF SIGNIFICANCE: Articular cartilage is a remarkable and sophisticated tissue that tolerates complex stresses within the joint. When injured, cartilage cannot self-repair, and these injuries often progress to joint-wide osteoarthritis, causing patients debilitating pain and loss of mobility. Current palliative and surgical treatments only provide short-term symptomatic relief and are limited with regards to efficiency and efficacy. Bioactive factors, such as drugs and growth factors, can improve outcomes to either stabilize the degenerated environment or regenerate replacement tissue. This review highlights recent advances and novel techniques to enhance the delivery, localization, retention, and activity of these factors, providing an overview of the cartilage drug delivery field that can guide future research in restorative and regenerative treatments for damaged cartilage.

Physical inactivity in aging and dementia: a review of its relationship to pain

AIMS

The goal of this brief review is to address studies examining the relationship between physical inactivity and pain in aging and dementia.

BACKGROUND

A decrease in the level of physical activity is characteristic of older persons, both with and without dementia. Passive behaviour is often considered to be part of the apathy frequently observed in patients with dementia, although it could also be a sign of pain. Design.  Literature review. Method.  Searches were performed in PubMed and Embase. A total of 15 studies concerning the relationship between physical inactivity and pain in older persons with and without dementia were identified (older persons without dementia: 12; with dementia: 3).

RESULTS

In older persons without dementia, a positive relationship between physical inactivity and pain has been demonstrated. In older persons with dementia, pain may cause physical inactivity and physical inactivity may cause pain. Conclusions.  In older persons, a positive relationship between physical inactivity and pain was demonstrated. More specifically, pain may cause physical inactivity. In older persons with dementia pain may cause physical inactivity and vice versa.

RELEVANCE TO CLINICAL PRACTICE

Nurses' awareness of physical inactivity as an indication of pain in older persons with and without dementia may reduce the risk of underdiagnosis and subsequent undertreatment of pain.