Study protocol for a pilot, randomised, double-blinded, placebo controlled trial of perineural local anaesthetics and steroids for chronic post-traumatic neuropathic pain in the ankle and foot: the PREPLANS study

Tibial Nerve Block as Treatment of Chronic Foot Pain

Background

Minimally invasive therapies can alleviate pain and improve walking in individuals with persistent foot and ankle pain.

Objectives

The current study aimed to define the protracted consequences of tibial nerve blocks with steroids for individuals with persistent foot pain and to investigate the link between the thermography of the plantar foot and the beneficial effect of a tibial nerve block with steroids.

Methods

All patients with chronic foot pain (n = 45) in this cohort underwent a block of the tibial nerve in the Department of Pain Therapy of Pain Clinic De Bilt, Utrecht, Netherlands, within November 2019 to April 2020. The thermographic images of patients were taken before and after injection. Results were retrospectively evaluated after 18 months.

Results

In this study, 53% of the patients had pain relief at 7 weeks of follow-up with a unilateral or bilateral block of the tibial nerve. An improvement in walking distance was reported by 22% of the patients. Side effects of the tibial nerve block reported at 7 weeks of follow-up increased pain (5%) and the occurrence of leg cramps (5%) among the treated patients. At 18 months, 45% of the successfully treated feet still had benefits. A difference between the big toe's temperature and the foot's average temperature of less than -0.9°C on thermography before and after the tibial nerve block can predict a beneficial result of therapy.

Conclusions

Tibial nerve block provides a safe, minimally invasive treatment option for almost half of the patients with painful feet in this cohort, and when successful, it can last a long term. Thermographic imaging of the plantar foot can predict only to a small extent the beneficial effect of the tibial nerve block with steroids on foot pain. Tibial nerve block should be considered when custom foot orthoses have been inadequate for pain relief or restricted walking distance.

Dexamethasone-Loaded biodegradable magnetic microparticles for treatment of CFA-induced chronic pain in rats

Traditional drug solutions or suspensions, have been shown to treat pain in complete Freund’s adjuvant (CFA)-induced chronic inflammatory pain in rats, with or without combination with magnetic therapy. In this study, we aimed to prepare, characterize, and evaluate the therapeutic effects of microparticles containing dexamethasone for local administration and treatment of chronic inflammatory pain. The results showed the following; a) Preparation and characterization: two ratios of poly(lactic-co-glycolic acid) (PLGA)/poly(lactic acid) (PLA) were used. The prepared batches were similar in size and magnetic responsiveness. The microparticle size distribution assessed via electron microscopy suggested a homogeneous distribution and absence of aggregates. Dexamethasone release profiles (microparticles synthesized with a feed ratio of 1:4) showed a sustained release in vitro and good biocompatibility with tissues. b) Therapeutic effect: the treatment effect of dexamethasone-PLGA magnetic microspheres + magnetic therapy was substantially better than that observed for other groups on day 4, as monitored by appearance, mechanical pain threshold, and histological analysis. This type of carrier could be a suitable magnetically retainable local drug delivery system for treating chronic pain.

CT can stratify patients as low risk for tibial neuropathy following a talus fracture

OBJECTIVE

Determine the incidence of tibial neuropathy following talus fractures and CT's ability to stratify patients at risk for developing post-traumatic neuropathy.

MATERIALS AND METHODS

In this IRB-approved retrospective analysis, 71 talus fractures and 8 contralateral control ankle CTs were reviewed by one observer blinded to clinical information. CT evidence suggestive of tibial neurovascular bundle injury included nerve displacement, perineural fat effacement/edema, and bone touching nerve. The association between these CT findings and clinically evident tibial neuropathy was analyzed. A semi-quantitative likelihood score was assigned based on the degree of the CT findings around the nerve. Interobserver agreement was calculated between 2 other readers.

RESULTS

Twenty-five percent of patients in this cohort had clinical evidence of tibial neuropathy. There was a high specificity (0.87-0.93) and negative predictive value (0.83-0.87), a moderate accuracy (0.80-0.82), but a lower sensitivity (0.33-0.56) associated with the CT findings. Among the CT findings, nerve displacement (p < 0.0001) and bone touching nerve (p = 0.01) were associated with tibial neuropathy. A likelihood score of 2-5 was associated (p = 0.007-0.015) with tibial neuropathy. The presence of tibial neuropathy and nerve recovery were not associated with hospital length of stay, while CT findings were. There was substantial agreement between the three readers: likelihood scores 2+ (k = 0.78) and 3+ (k = 0.72).

CONCLUSIONS

Tibial neuropathy occurs following talus fractures, and CT findings may help surgeons narrow down the number of patients requiring close neurological follow-up.