The effects of diabetes medications on post-operative long bone fracture healing

Diabetes and Impaired Fracture Healing: A Narrative Review of Recent Literature

PURPOSE OF THE REVIEW

Diabetes mellitus is a chronic metabolic disorder commonly encountered in orthopedic patients. Both type 1 and type 2 diabetes mellitus increase fracture risk and impair fracture healing. This review examines complex etiology of impaired fracture healing in diabetes.

RECENT FINDINGS

Recent findings point to several mechanisms leading to orthopedic complications in diabetes. Hyperglycemia and chronic inflammation lead to increased formation of advanced glycation end products and generation of reactive oxygen species, which in turn contribute to the disruption in osteoblast and osteoclast balance leading to decreased bone formation and heightening the risk of nonunion or delayed union as well as impaired fracture healing. The mechanisms attributing to this imbalance is secondary to an increase in pro-inflammatory mediators leading to premature resorption of callus cartilage and impaired bone formation due to compromised osteoblast differentiation and their apoptosis. Other mechanisms include disruption in the bone's microenvironment supporting different stages of healing process including hematoma and callus formation, and their resolution during bone remodeling phase. Complications of diabetes including peripheral neuropathy and peripheral vascular disease also contribute to the impairment of fracture healing. Certain diabetic drugs may have adverse effects on fracture healing. The pathophysiology of impaired fracture healing in diabetic patients is complex. This review provides an update of the most recent findings on how key mediators of bone healing are affected in diabetes.

Osteogenesis of adipose-derived stem cells from patients with glucose metabolism disorders

Background

Adipose derived stem cells (ADSCs) are clinically widely used somatic stem cells obtained from white adipose tissue. They are characterized by ability to differentiate e.g. into osteoblasts and might successfully regenerate bone tissue in fracture repair. However, the main problem of somatic stem cells is a documented influence of various diseases, drugs or age which can inhibit cells activity. Therefore, in the present study, we investigated the influence of insulin resistance (IR) and type 2 diabetes (T2D) on the proliferation and differentiation potential of ADSCs.

Methods

The fat from subcutaneous abdominal adipose tissue was acquired by lipoaspiration from 23 voluntary participants, divided into three groups: with diabetes type 2, with insulin resistance and control healthy donors. The proliferative potential was analyzed by cell cytotoxicity assays and by mRNA expression of genes connected with proliferation. Flow cytometry was done for identifying proteins characteristic for mesenchymal stem cells and an analysis of osteogenic differentiation potential based on the assessment of osteogenic markers by real time RT-qPCR, and the evaluation of calcium deposition were also performed.

Results

The results showed that diabetes type 2 lowered the activity of ADSCs in proliferation assays and changed their phenotypical characteristics. Interestingly, we observed differences in the proliferation potential of ADSCs in patients with insulin resistance, which is often the first phase of diabetes, compared to the control. It might suggest that insulin resistance, early-stage T2D, alters the activity of cells. Moreover, expression of osteogenesis markers was higher in cells from T2D patients than in cells from patients with IR and control.

Conclusion

We conclude that type 2 diabetes changes the activity of stem cells, and insulin resistance influences on the proliferation of ADSCs.

Hyperglycaemia is an under-appreciated but modifiable risk factor in managing people with type 1 diabetes and fragility fractures

There are two major musculoskeletal effects of Type 1 diabetes mellitus (T1DM) - fragility fractures and impaired fracture union. Fractures in these patients are a significant and limb threatening injury. Traditionally, they have been treated with prolonged immobilisation and as rigid as possible internal fixation. Recently, hyperglycaemia has been recognised as the most significant modifiable risk factor in treating patients with T1DM and fractured limbs. This article reviews this association further and outlines the role of orthopaedic surgeons in minimising orthopaedic-related complications.

Predictors of mechanical complications after intramedullary nailing of tibial fractures

INTRODUCTION

Intramedullary (IM) nailing is the gold standard treatment for tibial shaft fractures, but can be associated with various mechanical complications, including delayed union.

HYPOTHESIS

We believe that complications do not occur randomly, but in certain conditions that contribute to their development. Risk factors likely to predict delayed union can be identified to support prevention.

MATERIALS AND METHODS

A cohort of 171 fractures treated by IM nailing between 2005 and 2015 was reviewed retrospectively. Independent variables included intrinsic, patient-related factors and extrinsic factors such as those related to the fracture or surgery. A multiple logistic regression model was used to determine which factors can predict each type of complication.

RESULTS

Delayed union occurred in 22.8% of patients. Smoking and high-energy trauma were risk factors. Hardware breakage was significantly reduced (p<0.05) when the nail diameter was greater than 10mm. A nail diameter/reamer diameter ratio outside the recommended limits (0.80-0.99) was more likely to be associated with screw failure. Diabetes is a risk factor for hardware migration, which itself is associated with other complications.

DISCUSSION

Nonunion is the most common complication after IM nailing of tibial shaft fractures. Smoking cessation after a fracture is necessary in our opinion, even if the literature is ambivalent on this aspect and stopping to smoke once the fracture occurs may not be sufficient to prevent a poor outcome. Use of a nail diameter/reamer diameter between 0.80 and 0.99 favors union and prevents hardware breakage. Hardware migration in a diabetic patient may be a warning sign of other types of complications.

LEVEL OF EVIDENCE

Retrospective cohort study. Level IV.

Time dependent loss of trabecular bone in human tibial plateau fractures

We investigated if time between injury and surgery affects cancellous bone properties in patients suffering tibial plateau fractures (TPF), in terms of structural integrity and gene expression controlling bone loss. A cohort of 29 TPF, operated 1-17 days post-injury, had biopsies from the fracture and an equivalent contralateral limb site, at surgery. Samples were assessed using micro-computed tomography and real-time RT-PCR analysis for the expression of genes known to be involved in bone remodeling and fracture healing. Significant decreases in the injured vs control side were observed for bone volume fraction (BV/TV, -13.5 ± 6.0%, p = 0.011), trabecular number (Tb.N, -10.5 ± 5.9%, p = 0.041) and trabecular thickness (Tb.Th, -4.6 ± 2.5%, p = 0.033). Changes in these parameters were more evident in patients operated 5-17 days post-injury, compared to those operated in the first 4 days post-injury. A significant negative association was found between Tb.Th (r = -0.54, p < 0.01) and BV/TV (r = -0.39, p < 0.05) in relation to time post-injury in the injured limb. Both BV/TV and Tb.Th were negatively associated with expression of key molecular markers of bone resorption, CTSK, ACP5, and the ratio of RANKL:OPG mRNA. These structure/gene expression relationships did not exist in the contralateral tibial plateau of these patients. This study demonstrated that there is a significant early time-dependent bone loss in the proximal tibia after TPF. This bone loss was significantly associated with altered expression of genes typically involved in the process of osteoclastic bone resorption but possibly also bone resorption by osteocytes. The mechanism of early bone loss in such fractures should be a subject of further investigation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2865-2875, 2018.

The Impact of Type 2 Diabetes on Bone Fracture Healing

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease known by the presence of elevated blood glucose levels. Nowadays, it is perceived as a worldwide epidemic, with a very high socioeconomic impact on public health. Many are the complications caused by this chronic disorder, including a negative impact on the cardiovascular system, kidneys, eyes, muscle, blood vessels, and nervous system. Recently, there has been increasing evidence suggesting that T2DM also adversely affects the skeletal system, causing detrimental bone effects such as bone quality deterioration, loss of bone strength, increased fracture risk, and impaired bone healing. Nevertheless, the precise mechanisms by which T2DM causes detrimental effects on bone tissue are still elusive and remain poorly studied. The aim of this review was to synthesize current knowledge on the different factors influencing the impairment of bone fracture healing under T2DM conditions. Here, we discuss new approaches used in recent studies to unveil the mechanisms and fill the existing gaps in the scientific understanding of the relationship between T2DM, bone tissue, and bone fracture healing.