Aims

Computer-based applications are increasingly being used by orthopaedic surgeons in their clinical practice. With the integration of technology in surgery, augmented reality (AR) may become an important tool for surgeons in the future. By superimposing a digital image on a user’s view of the physical world, this technology shows great promise in orthopaedics. The aim of this review is to investigate the current and potential uses of AR in orthopaedics.

Purpose

Conservative treatment of minimally displaced distal radius fractures (DFR) remains controversial. Circumferential casting (CC) in the acute setting is believed to supply superior support compared to splinting, but is generally cautioned due to the limited capacity of a cast to accommodate ongoing limb swelling possibly leading to complications. However, there is no conclusive data on which to base these beliefs. Moreover, the appropriate management of cast complications while minimizing risk to fracture integrity remains unclear.

This retrospective study of distal radius fractures treated conservatively with circumferential cast in the acute setting aims to: A. Determine demographic, fracture dependant or management risk factors for CC complications. B. Determine the natural history for both patients with CC and those with CC necessitating cast modification.

Purpose

Internal fixation of fractures in the presence of osteopenia has been associated with a failure rate as high as 25%. Enhancing bone formation and osseointegration of orthopaedic hardware is a priority when treating patients with impaired bone regenerative capacity. Fibroblast Growth Factor (FGF) 18 regulates skeletal development and could therefore have applications in implant integration. This study was designed to determine if FGF 18 promotes bone formation and osseointegration in the osteopenic FGFR3−/− mouse and to examine its effect on bone marrow derived mesenchymal stem cells (MSCs).

Purpose: Poor bone quality is a common challenge to orthopaedic surgeons and frequently leads to complications such as non union and implant failure, particularly the elderly whose capacity for tissue repair is significantly reduced. The current study was designed to determine if bone marrow derived mesenchymal stem cells (MSC) seeded in dense collagen scaffolds and delivered to a surgically-induced femoral defect will expedite bone healing.

Method: Ex Vivo: MSC isolated from four month old donor mice were expanded ex vivo, seeded into hydrated type I collagen, which was subjected to unconfined compression to generate dense collagen scaffolds. The cell-seeded scaffolds were then cultured for up to 21 days. MSC viability was monitored using the AlamarBlue^® metabolic assay and differentiation into osteoblasts using alkaline phosphatase (ALP) and von Kossa stain. In Vivo: A 3mm x 1mm window defect was drilled in the femur of elderly recipient C57Bl6 and C3H mice. The C3H mice were assigned to one of two study groups:

LEFT femur drill hole alone; RIGHT femur acellular scaffold.

The quantity and quality of bone regeneration was assessed after 2 and 4 weeks using micro computed tomography (mCT) and histology.

Results: Ex Vivo: The dense collagen scaffold had superior mechanical properties and supported the survival and differentiation of MSC into osteoblasts up to 21 days in culture. Cells in uncompressed gels and those in compressed gels in non-osteogenic medium, had fewer ALP-positive cells at early time point and less mineral deposited at later times compared with those in compressed gels in osteogenic medium. In Vivo: A high incidence of postoperative fracture was seen in C57Bl6 mice compared with age matched C3H mice in the first study group. Furthermore, the empty surgical defect healed more rapidly than that containing the dense collagen scaffold, in which bone volume compared with tissue volume (BV/TV), trabecular number (Tb.N.) and connectivity were lower. In study group two, bone regeneration was evident at 2 weeks post operative and transplantation of MSC-seeded dense collagen scaffolds resulted in higher BV/TV, Tb.N. and trabecular connectivity compared with the acellular dense collagen scaffold.

Conclusion: Bone fragility in elderly C57Bl6 mice led to post operative fracture after generation of a non-critical sized drill hole defect in the proximal femur whereas age-matched C3H mice with higher bone mass sustained no fractures. Dense collagen scaffolds supported the survival and osteoblast differentiation of bone marrow derived MSC in 3D culture. Their superior mechanical properties allowed for transplantation into non-critical sized femoral defects, suggesting the approach shows promise as adjunct therapy for use with bone grafts and implants in patients with poor quality bone.

Purpose: Glucocorticoids (GCs) are widely prescribed drugs in a large variety of diseases. Their use are strongly influenced by their associated negative side effects. Bone-related effects are mainly osteoporosis and osteonecrosis (ON). Despite the strong link between GCs and ON, the pathogenic mechanisms by which GCs cause ON are still unclear. Cumulative evidence shows that dysfunction or activation of endothelial cells (ECs) play an important role in ON.

Method: In this study, we investigated the influence of dexamethasone (Dex) on the Tumor Necrosis Factor-alpha [TNF-alpha] or Lipopolysaccharide [LPS] or Thrombin [IIa] -stimulated Human Umbilical Vein Endothelial Cells (HUVEC). We examined the molecular expression of 9 candidate genes (E-selectin [E-Sel], Intracellular adhesion molecule-1 [ICAM-1], Plasminogen activator inhibitor-1 [PAI-1], Tissue Factor [TF], Tissue plasminogen activator [t-PA], Urokinase plasminogen activator [u-PA], Vascular adhesion molecule-1 [VCAM-1], Von Willebrand Factor [vWF] and Thrombomodulin [THBD]) by real-time PCR. Live cell number of HUVEC under exposure to Dex was also assayed by viability test. All experiments were performed in triplicates and Standard error of the mean (SEM) was obtained.

Results: We showed that Dex alone significantly induced the expression of E-Sel, ICAM-1, TF, VCAM-1 and VWF while downregulating THBD and U-PA expression. Our results also showed a significant priming effect of Dex on E-Sel and TF inflammatory-mediated induction by TNF-alpha and LPS respectively. Comparable results were obtained from Northern Blot analysis; results from FACS analysis and Functional assays will be presented at the meeting.

Conclusion: Our observations suggest a procoagulant activity of Dex on HUVEC. We also observed a priming activity of Dex on E-Sel and TF inflammatory-mediated induction. These results suggest a potential endothelial cell activation mechanism and subsequent microvascular thrombosis in glucocorticoid-induced ON.

Radial-sided avulsions of the TFCC (Palmer 1d) remain a challenging pathology to treat. No current procedures have addressed these injuries successfully and reproducibly. Ten preserved dissected cadaveric forearm specimens with intact TFCC and without ulnar positive variance underwent biomechanical testing. Specimens were tested intact, then with Palmer 1d TFCC lesion and finally post-reconstruction. Measurement of total displacement with a −20N to 20N load was performed. The results indicate that our novel anatomic intra-articular reconstruction of unstable radial-sided TFCC avulsions was successful in restoring baseline stability to the DRUJ without interfering with pronation or supination.

Radial-sided avulsions of the TFCC (Palmer 1d) remain a challenging pathology to treat. No current procedures have addressed these injuries successfully and reproducibly. We tested a novel intra-articular reconstruction to address unstable radial-sided TFCC avulsions.

Ten preserved dissected cadaveric forearm specimens with intact TFCC and without ulnar positive variance underwent biomechanical testing using an MTS machine. Measurement of total displacement with a −20N to 20N load was performed. Specimens were tested intact, then with Palmer 1d TFCC lesion and finally post-reconstruction. All tests were performed at neutral, maximal pronation and maximal supination.

Mean total displacements of the specimens at neutral rotation were: 4.122mm ± 0.363 for the intact specimens compared to 11.839mm ± 0.782 after creation of the tear (p< 0.000002) and 3.883mm ± 0.655 for the reconstructed specimens (p=0.77). In maximal pronation mean total displacements were: 2.378mm ± 0.250 intact vs. 4.922 ± 0.657 torn (p< 0.0007) and 2.124mm ± 0.339 post-reconstruction (p=0.61). In maximal supination mean total displacements were: 1.438mm ± 0.222 intact vs. 5.704mm ± 1.258 torn (p< 0.006) and 1.004mm ± 0.091 post-reconstruction (p=0.07). All specimens obtained the same maximal pronation and supination pre and post-reconstruction.

Restoration of stability and joint function have never been achieved with previous reconstruction attempts of radial-sided TFCC avulsions. Current procedures are unable to restore DRUJ stability without a significant sacrifice of motion. Our anatomic intra-articular reconstruction of unstable radial-sided TFCC avulsions succeeded in restoring baseline stability to the DRUJ without interfering with pronation/supination.

To determine if immediate closure of open wounds is safe, we examined our results over a five year period. Of the two hundred and ninety-seven open fractures, two hundred and fifty-five (86 %) were closed immediately. Grade III open fractures accounted for 24.2% of cases. The superficial infection rate was 10.9%. The combined deep infection and osteomyelitis rate was 4.7%. Neither region of injury, Gustilo grade, velocity of trauma, nor time to primary closure had a significant influence on the incidence of infection. Primary closure may be a safe practice and could be accepted as a viable treatment plan in the care of most open fractures.

The purpose of this study was to determine if immediate primary closure of open fracture wounds is a safe practice without increased deep infections and delayed/ nonunions?

There was neither an increase in deep infection nor delayed union/non-union. Benefits include a decreased requirement for repeat debridements and soft tissue procedures, minimized surgical morbidity, hospital stay, and cost of treatment. Primary closure may be a safe practice in the care of most open fractures.

The standard of care has been to leave traumatic wounds open after initial emergent surgical debridement. Due to orthopedic advancements and current resource limitations, treatment at our institution has evolved to immediate closure of all open wounds after adequate irrigation and debridement.

Of the two hundred and ninety-seven open fractures, two hundred and fifty-five (86 %) were closed immediately after irrigation and debridement. Grades 3a, 3b and 3c open fractures accounted for 24.2% of cases. The superficial infection rate of primary closure was 10.9 %. All cases resolved with oral antibiotics. The combined deep infection and osteomyelitis rate was 4.7%. Neither region of injury, Gustilo grade, velocity of trauma, nor time to primary closure had a significant influence on the incidence of infection.

The study reviewed all open fractures presenting to a Level One Trauma center over a five-year study period. Patients were followed until fracture union or complication resolution. Multiple variables were examined including patient demographics, injury mechanism, fracture location, Gustilo classification, time to antibiotic administration, surgical debridement and wound closure, and method of wound closure. Outcome measurement included infection or union problems.

The effect of zoledronic acid on bone ingrowth was examined in an animal model in which porous tantalum implants were placed bilaterally within the ulnae of seven dogs. Zoledronic acid in saline was administered via a single post-operative intravenous injection at a dose of 0.1 mg/kg. The ulnae were harvested six weeks after surgery. Undecalcified transverse histological sections of the implant-bone interfaces were imaged with backscattered scanning electron microscopy and the percentage of available pore space that was filled with new bone was calculated. The mean extent of bone ingrowth was 6.6% for the control implants and 12.2% for the zoledronic acid-treated implants, an absolute difference of 5.6% (95% confidence interval, 1.2 to 10.1) and a relative difference of 85% which was statistically significant. Individual islands of new bone formation within the implant pores were similar in number in both groups but were 69% larger in the zoledronic acid-treated group. The bisphosphonate zoledronic acid should be further investigated for use in accelerating or enhancing the biological fixation of implants to bone.

We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant.

These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation.