Role of coatings and materials of external fixation pins on the rates of pin tract infection: A systematic review and meta-analysis

In-vitro external fixation pin-site model proof of concept: A novel approach to studying wound healing in transcutaneous implants

External fixation is an essential surgical technique for treating trauma, limb lengthening and deformity correction, however infection is common, with infection rates ranging from 4.5 to 100% of cases. Throughout the literature researchers and clinicians have highlighted a relationship between excessive movement of the pin and skin and an increase in the patient's risk of infection, however, currently no studies have addressed this role of pin-movement on pin-site wounds. This preliminary study describes a novel in vitro pin-site model, developed using a full-thickness human skin equivalent (HSE) model in conjunction with a bespoke mechanical system which simulates pin-movement. The effect of pin-movement on the wound healing response of the skin equivalents was assessed by measuring the expression of pro-inflammatory cytokines. Six human skin equivalent models were divided into three test groups: no pin as the control, static pin-site wound and dynamic pin-site wound (n = 3). On day 3 concentrations of IL-1α and IL-8 showed a significant increase compared to the control when a static fixation pin was implanted into the skin equivalent (p < 0.05) and (p < 0.005) respectively. Levels of IL-1α and IL-8 increased further in the dynamic sample compared to the static sample (p < 0.05) and (p < 0.0005). This study demonstrates for the first time the application of HSE model to study external-fixation pin-movement in vitro. The results of this study demonstrated pin-movement has a negative effect on soft-tissue wound-healing, supporting the anecdotal evidence reported in the literature, however further analysis of wound heading would be required to verify this hypothesis.

Hydrotherapy for Patients With External Fixation: Effect on Infectious Events

BACKGROUND

Surgery to achieve long bone lengthening and deformity correction in skeletally immature patients is traditionally performed through external fixators. The incidence of infection during treatment is high. Hydrotherapy is highly beneficial during external fixation management, but the infection rates may impact its utilization. The objective of this paper is to document the incidence and duration of infection in patients who participated in a full hydrotherapy program when performed under medical supervision and in accordance with strict follow-up protocols.

METHODS

In this retrospective study, we documented the key characteristics of patients who participated in hydrotherapy after lower limb external fixation surgery including age, sex, diagnosis and surgery site, the incidence and duration of pin site infections, and the percentage of cases, which were able to comply with a full hydrotherapy protocol.

RESULTS

The hydrotherapy pool met all daily water quality metrics. Thirty-four children (19 males and 15 females) had a mean±SD age of 10.9±4.6 years. Of the cases, 80% were unilateral and 20% were bilateral. Diagnoses included congenital hereditary (eg, achondroplasia), congenital nonhereditary conditions (eg, fibular hemimelia), and acquired conditions (eg, traumatic). The location of osteotomy site was quite evenly spread between the femur and the tibia/fibula. Three out of the 34 patients were unable to receive hydrotherapy due to continuous secretions; 2 patients did not miss any sessions. The mean number of treatments was 3 per week. During the entire period, a total of 1200 treatments were performed for these patients with only 32 cancellations (about 3%) due to secretions or other signs of infection. Spearman correlation coefficients showed significantly high correlations between the duration of external fixation and the duration of hydrotherapy. There are no significant correlations between infections and other factors (sex, age segment, whether the problem is unilateral or /bilateral, diagnosis, and duration of treatment).

CONCLUSIONS

This is the first report, to our knowledge, that documents the low prevalence of infectious events during hydrotherapy treatment and demonstrates its feasibility.

LEVEL OF EVIDENCE

Level III; retrospective, comparative study.

Hydroxyapatite-coated compared with stainless steel external fixation pins did not show impact in the rate of pin track infection: a multicenter prospective study

PURPOSE

Infection at the pin site remains the most common complication of external fixators (EFs). It is known that hydroxyapatite (HA)-coated pins increase bone adhesion and may lead to reduced rates of reported infections. The present study compares the rates of pin track infection associated with stainless steel and HA-coated pins.

METHODS

This is a prospective, multicenter, nonrandomized, comparative intervention study among patients undergoing surgical treatment with EFs of any type between April 2018 and October 2021. Patients were followed up until the removal of the EF, or the end of the study period (ranging from 1 to 27.6 months). The definition of pin track infection was based upon the Maz-Oxford-Nuffield (MON) pin infection grading system.

RESULTS

Overall, 132 patients undergoing external fixation surgery were included. Of these, 94 (71.2%) were male, with a mean age of 36.9 years (SD ± 18.9). Infection of any type (score > 1) was observed in 63 (47.7%) patients. Coated and uncoated-pin track-infection occurred in 45.7% and 48.5% of patients, respectively (P= 0.0887). The probability of developing infection (defined as a score ≥ 2) adjusted for comorbidities and follow-up time was not statistically higher among those who received uncoated pins compared to those who received pins coated with HA (odds ratio (OR) = 1.56, 95% confidence interval (95% CI): 0.67-3.67, p <0.05).

CONCLUSION

In the present study, the external fixator pin infection rates were similar when using HA coating and standard steel pins.

A concise review on implications of silver nanoparticles in bone tissue engineering

Skeletal disorders represent a variety of degenerative diseases that affect bone and cartilage homeostasis. The regenerative capacity of bone is affected in osteoporosis, osteoarthritis, rheumatoid arthritis, bone fractures, congenital defects, and bone cancers. There is no viable, non-invasive treatment option and bone regeneration requires surgical intervention with the implantation of bone grafts. Incorporating nanoparticles in bone grafts have improved fracture healing by providing fine structures for bone tissue engineering. It is currently a revolutionary finding in the field of regenerative medicine. Silver nanoparticles (AgNPs) have garnered particular attention due to their well-known anti-microbial and potential osteoinductive properties. In addition, AgNPs have been demonstrated to regulate the proliferation and differentiation of mesenchymal stem cells (MSCs) involved in bone regeneration. Furthermore, AgNPs have shown toxicity towards cancer cells derived from bone. In the last decade, there have been multiple studies focusing on the effect of nanoparticles on the proliferation and/or differentiation of MSCs and bone cancer cells; however, the specific studies with AgNPs are limited. Although the reported investigations show promising in vitro and in vivo potential of AgNPs for application in bone regeneration, more studies are required to ensure their implications in bone tissue engineering. This review aims to highlight the current advances related to the production of AgNPs and their effect on MSCs and bone cancer cells, which will potentiate their possible implications in orthopedics. Moreover, this review article evaluates the future of AgNPs in bone tissue engineering.