Principles of fixation of osteoporotic fractures

Severity of Complications after Locking Plate Osteosynthesis in Distal Femur Fractures

Background: Locked plating for distal femur fractures is widely recommended and used. We systematically reviewed clinical studies assessing the benefits and harms of fracture fixation with locked plates in AO/OTA Type 32 and 33 femur fractures. Methods: A comprehensive literature search of PubMed, Embase, Cinahl, Web of Science, and the Cochrane Database was performed. The studies included randomized and non-randomized clinical trials, observational studies, and case series involving patients with distal femur fractures. Studies of other fracture patterns, studies conducted on children, pathological fractures, cadaveric studies, animal models, and those with non-clinical study designs were excluded. Results: 53 studies with 1788 patients were found to satisfy the inclusion and exclusion criteria. The most common harms were nonunion (14.8%), malunion (13%), fixation failure (5.3%), infection (3.7%), and symptomatic implant (3.1%). Time to full weight-bearing ranged from 5 to 24 weeks, averaging 12.3 weeks. The average duration of follow-up was 18.18 months, ranging from 0.5 to 108 months. Surgical time ranged between 40 and 540 min, with an average of 141 min. The length of stay in days was 12.7, ranging from 1 to 61. The average plate length was ten holes, ranging from 5 to 20 holes. Conclusion: This review aimed to systematically synthesize the available evidence on the risk associated with locked plating osteosynthesis in distal femur fractures. Nonunion is the most common harm and is the primary cause of reoperation. The overall combined risk of a major and critical complication (i.e., requiring reoperation) is approximately 20%.

Restoring implant fixation strength in osteoporotic bone with a hydrogel locally delivering zoledronic acid and bone morphogenetic protein 2. A longitudinal in vivo microCT study in rats

Osteoporosis poses a major public health challenge, and it is characterized by low bone mass, deterioration of the microarchitecture of bone tissue, causing a consequent increase in bone fragility and susceptibility to fractures and complicating bone fixation, particularly screw implantation. In the present study, our aim was to improve implant stability in osteoporotic bone using a thermoresponsive hyaluronan hydrogel (HA-pNIPAM) to locally deliver the bisphosphonate zoledronic acid (ZOL) to prevent bone resorption and bone morphogenetic protein 2 (BMP2) to induce bone formation. Adult female Wistar rats (n = 36) were divided into 2 treatment groups: one group of SHAM-operated animals and another group that received an ovariectomy (OVX) to induce an osteoporotic state. All animals received a polyetheretherketone (PEEK) screw in the proximal tibia. In addition, subgroups of SHAM or OVX animals received either the HA-pNIPAM hydrogel without or with ZOL/BMP2, placed into the defect site prior to screw implantation. Periprosthetic bone and implant fixation were monitored using longitudinal in vivo microCT scanning post-operatively and at 3, 6, 9, 14, 20 and 28 days. Histological assessment was performed post-mortem. Our data showed that pure hydrogel has no impact of implant fixation The ZOL/BMP2-hydrogel significantly increased bone-implant contact and peri-implant bone fraction, primarily through reduced resorption. STATEMENT OF CLINICAL SIGNIFICANCE: Local delivery of ZOL and BMP2 using a biocompatible hydrogel improved implant stability in osteoporotic bone. This approach could constitute a potent alternative to systemic drug administration and may be useful in avoiding implant loosening in clinical settings.

Early surgery improves survival after femoral fractures in the elderly: A retrospective review of 502 fragility fractures

AIMS

Fragility fractures are a growing global healthcare burden; fragility fractures of the femur have been shown to occur in a highly comorbid patient group, with parallels to hip fracture patients. This study aimed to investigate if early surgery for femoral fractures, distal to the hip, resulted in a reduction in mortality in patients over 65 years of age.

METHODS

A retrospective review of prospectively collected data for all consecutive femoral fractures in patients aged over 65 years who underwent surgical management between January 2000 and December 2018. Data was extracted from the Fracture Outcomes Research Database (FORD) and analysed to assess if early surgery, defined as occurring within 48 h of hospital admission with a fragility femur fracture, had an effect on 30 day and 1 year mortality.

RESULTS

502 eligible patients were included; median follow up time was 57 months. 24 patients (4.7%) died within 30 days of surgery and 105 patients (20.9%) had died within 1 year of surgery. Patients who underwent surgery within 48 h of admission had a significantly reduced chance of mortality within 1 year of surgery compared to patients who had surgery more than 48 h after admission (OR = 0.401, 95% CI 0.25-0.65, p<0.001). Following Multivariate Cox Regression analysis the hazard ratio of 1 year mortality following early surgery remained significantly reduced (HR = 0.57, 95% CI 0.36-0.92, p = 0.020).

CONCLUSIONS

This study demonstrates that fragility femoral fracture patients represent a similar cohort to hip fracture patients, with high mortality rates. We recommend that hip fracture management principles are also employed for fragility femoral fractures in patients over 65 years, with rapid pre-operative optimisation to ensure these patients undergo early surgical intervention.

Influence of bone density on stability in TBW

Osteoporosis is a common disease that leads to a reduction in bone density and increases the risk of fractures. Stable surgical treatment is particularly important for these fractures. The aim of this study was to examine the influence of bone density in the area of ​​the proximal ulna on the failure of the fixation technique of K-wires in tension band wiring (TBW). We provided 10 ulna specimens with TBW and biomechanically examined the pull-out strength of bi- and tricortical K-wires. Bone density measurement was performed using qCT. In the paired t-test, the tricortical group showed a significantly higher pull-out strength in relation to bone density than the bicortical group (p = 0.001). Furthermore, the Pearson correlation showed a high influence of bone density on pull-out strength in the tricortical group (r = 0.544), but without significance (p = 0.100).Our work shows that bone density has a direct effect on the pull-out strength of K-wires in TBW. TBW should therefore be used as osteosynthesis technique, especially in young patients with non-osteoporotic bones. In the case of osteoporotic fractures, alternative procedures should be preferred.

Predictive risk factors for mechanical complications after multilevel posterior cervical instrumented fusion

OBJECTIVE

Mechanical complications should be considered following the correction of multilevel posterior cervical instrumented fusion. This study aimed to investigate clinical data on the patients' pre- and postoperative cervical alignment in terms of the incidence of mechanical complications after multilevel posterior cervical instrumented fusion.

METHODS

Between January 2008 and December 2018, 156 consecutive patients who underwent posterior cervical laminectomy and instrumented fusion surgery of 4 or more levels and were followed up for more than 2 years were included in this study. Age, sex, bone mineral density (BMD), BMI, mechanical complications, and pre- and postoperative radiographic factors were analyzed using multivariate logistic regression analysis to investigate the factors related to mechanical complications.

RESULTS

Of the 156 patients, 114 were men and 42 were women; the mean age was 60.38 years (range 25-83 years), and the mean follow-up duration of follow-up was 37.56 months (range 24-128 months). Thirty-seven patients (23.7%) experienced mechanical complications, and 6 of them underwent revision surgery. The significant risk factors for mechanical complications were low BMD T-score (-1.36 vs -0.58, p = 0.001), a large number of fused vertebrae (5.08 vs 4.54, p = 0.003), a large preoperative C2-7 sagittal vertical axis (SVA; 32.28 vs 23.24 mm, p = 0.002), and low preoperative C2-7 lordosis (1.85° vs 8.83°, p = 0.001). The clinical outcomes demonstrated overall improvement in both groups; however, the neck visual analog scale, Neck Disability Index, and Japanese Orthopaedic Association scores after surgery were significantly worse in the mechanical complication group compared with the group without mechanical complications.

CONCLUSIONS

Low BMD, a large number of fused vertebrae, a large preoperative C2-7 SVA, and low C2-7 lordosis were significant risk factors for mechanical complications after posterior cervical fusion surgery. The results of this study could be valuable for preoperative counseling, medical treatment, or surgical planning when multilevel posterior cervical instrumented fusion surgery is performed.

How Efficient are Alendronate-Nano/Biomaterial Combinations for Anti-Osteoporosis Therapy? An Evidence-Based Review of the Literature

Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. Because of the systemic nature of osteoporosis, the associated escalation in fracture risk affects virtually all skeletal sites. The problem is serious since it is estimated that more than 23 million men and women are at high risk of osteoporotic-like breakages in the European Union. Alendronate (ALN) is the most commonly prescribed oral nitrogen-containing bisphosphonate (BP) for the prevention and the therapy of osteoporosis. This is also one of the most intensely studied drugs in this field. However, ALN is characterized by restricted oral absorption and bioavailability and simultaneously its administration has serious side-effects (jaw osteonecrosis, irritation of the gastrointestinal system, nausea, musculoskeletal pain, and cardiovascular risks). Therefore, delivery systems enabling controlled release and local action of this drug are of great interest, being widely researched and presented in the literature. In this review, we discuss the current trends in the design of various types of alendronate carriers. Our paper is focused on the most recent developments in the field of nano/biomaterials-based systems for ALN delivery, including nano/microformulations, synthetic/natural polymeric and inorganic materials, hydrogel-based materials, scaffolds, coated-like structures, as well as organic-inorganic hybrids. Topics related to the treatment of complex bone diseases including osteoporosis have been covered in several more general reviews; however, the systems for this particular drug have not yet been discussed in detail.

Gaps and alternative surgical and non-surgical approaches in the bone fragility management: an updated review

Osteoporotic fractures are one of the major problems facing healthcare systems worldwide. Undoubtedly, fragility fractures of the hip represent a far greater burden in terms of morbidity, mortality, and healthcare costs than other fracture sites. However, despite the significant impact on the health and quality of life of older adults, there is a general lack of awareness of osteoporosis, which results in suboptimal care. In fact, most high-risk individuals are never identified and do not receive adequate treatment, leading to further fragility fractures and worsening health status. Furthermore, considering the substantial treatment gap and the proven cost-effectiveness of fracture prevention programs such as Fracture Liaison Services, urgent action is needed to ensure that all individuals at high risk of fragility fracture are adequately assessed and treated. Based on this evidence, the aim of our review was to (i) provide an overview and comparison of the burden and management of fragility fractures, highlighting the main gaps, and (ii) highlight the importance of using alternative approaches, both surgical and non-surgical, with the aim of implementing early prevention of osteoporotic fractures and improving the management of osteoporotic patients at imminent and/or very high risk of fracture.

The use of suprapectineal plate in acetabular fractures via ilioinguinal approach with Stoppa window

Objective

The aim of the study was to investigate the clinical results of open reduction and internal fixation using a suprapectineal buttress plate for specific acetabular fractures.

Methods

We conducted a retrospective study involving thirty-three patients with specific acetabular fractures in an academic level 2 trauma center. We performed the ilioinguinal approach with Stoppa window for buttress plating of the quadrilateral surface. Clinical examination, radiographs and computed tomography were done using criteria described by Matta. Functional outcome was evaluated by visual analog scale (VAS), WOMAC, Harris Hip score modified, Hip disability and Osteoarthritis Outcome Score (HOOS) and modified Merle d’Aubignè scoring system.

Results

Average follow-up was 40.4 months with a minimum of 24 months. Mean age was 59.09 years. The 82% of patients were treated with a suprapectineal plate using ilioinguinal approach with Stoppa window. The 18% of patients required a Kocher-Langenbeck approach in order to get anatomic reduction of posterior wall or column. The 91% of patients were satisfied of their condition during activity of day living and only a small cohort reported walking aids. The worst clinical results were obtained in patients characterized by highest step displacement. Deep infection of surgical wound was observed in 6% of patients. In 3% of patients, one vascular injury occurred during surgery.

Conclusion

Internal fixation using ilioinguinal approach with Stoppa window and a suprapectineal plate to buttress the quadrilateral plate should be considered a viable treatment of some acetabular fractures. Patients can expect a good functional outcome with a low complication rate.

Hounsfield unit measurement method and related factors that most appropriately reflect bone mineral density on cervical spine computed tomography

OBJECTIVE

Our study's purpose was to determine the most reliable Hounsfield unit (HU) measurement method to reflect bone mineral density (BMD) on cervical spine computed tomography (CT) and to identify any factors that influence these results.

MATERIALS AND METHODS

We retrospectively analyzed 439 consecutive patients with mild head and neck injuries. Mean HU values of the C2-C7 vertebra were determined on each sagittal, coronal, and axial CT image. Correlation patterns were analyzed between the HU value and corresponding dual-energy X-ray absorptiometry (DXA) in the lumbar vertebra (T-score) and femoral neck (T-score). A sub-group analysis was performed according to patient age, sex, and degree of spinal degeneration.

RESULTS

The correlation coefficients for HU and DXA ranged from 0.52 to 0.65 in all cervical segments. A simple linear regression analysis revealed the following formula: T-score = 0.01 × (HU) - 4.55. The mean HU values for osteopenia and osteoporosis were 284.0 ± 63.3 and 231.5 ± 52.8, respectively. The ROC curve indicated that the HU method has a sensitivity of 89.2% and specificity of 88.7% to diagnose osteoporosis. The HU measurement showed a high correlation value (range: r = 0.64-0.70) with spine DXA score regardless of the degree of degeneration or patient age or sex.

CONCLUSION

HU values using the upper two cervical vertebrae (C2 and C3) reflected a more reliable BMD level than other segments. Additionally, the HU of cervical CT provided reliable information regardless of measurement plane, age or sex, and degree of degeneration.

Locking in trochanteric fractures: a comparison of static versus dynamic locking using the Gamma3 nail

PURPOSE

The Gamma3 nail (Stryker®) is an intramedullary device consisting of a proximal lag screw and distal interlocking screw. It is still unknown whether the screw locking mode could influence clinical outcomes. The aim of this study is to compare static and dynamic screw locking regarding their influence on surgical revisions and lag screw displacement.

METHODS

A retrospective single-centre study was performed on patients ≥ 60 years admitted for a trochanteric fracture between September 2016 and January 2020. Surgical revisions and lag screw displacement were evaluated at 6 weeks and 1-year follow-up, respectively.

RESULTS

A total of 142 patients were included for analysis. Surgical revisions were needed in 13 cases (9.2%). Indications included implant breakage (n = 3), lag screw cut-out (n = 3), lateral hip pain (n = 6) and non-union (n = 1). The number of surgical revisions was not different between static and dynamic locking (OR 2.55; 95%CI 0.73-8.56; p 0.142). The median lag screw displacement was 2.5 mm, which was similar for static and dynamic locking (2.3 mm versus 2.7 mm; p 0.785).

CONCLUSION

The screw locking mode of the Gamma3 nail is not associated with a higher risk of surgical revisions. However, the design of the Gamma3 nail may not be suitable for static locking.

A finite element study of a fractured tibia treated with a unilateral external fixator: The effects of the number of pins and cortical thickness

INTRODUCTION

In the early stage of fracture fixation, the aim of a unilateral external fixator (UEF) to stimulate healing and maintain stability may be suppressed by using inadequate number of pins. Cortical thinning due to age or osteoporosis endangers a successful fracture fixation.

MATERIALS AND METHODS

This study evaluates the initial strength and stability of the fracture fixation and tissue differentiation under the influences of variable cortical thickness (5 mm to 1 mm) and variable number of pins (1 to 4 in each bone fragment). A finite element program was utilised to develop 20 three-dimensional models of simplified diaphyseal tibia with fracture callus fixed with UEF. A mechano-regulation code based on the deviatoric strain theory was written and applied to simulate tissue differentiation. The values of von Mises stress, interfragmentary strain (IFS), and fibrocartilage index (FCI) were evaluated.

RESULTS

Cortical thinning from 5 mm to 1 mm increased IFS and FCI by an average of 30.3% and 18.7%, respectively, and resulted in higher stresses in the UEF and bone. Using 1 pin in each bone fragment produced excessive IFS in the models with 1 mm, 2 mm and 3 mm cortical thickness. Inserting the second pin into the bone fragment could considerably reduce the IFS and fibrocartilaginous tissue formation in the fracture site and improve load transmission to the fixator. Whereas inserting the fourth pin could minimally affect the mechano-biological environment of healing.

CONCLUSIONS

This study suggests that initial instability due to cortical thinning can be efficiently alleviated by adding the number of pins up to 3 in a UEF; additionally, it may improve the knowledge about applying UEFs adequately stable, whilst promoting inclination toward endochondral ossification, simultaneously.

Non-linear explicit micro-FE models accurately predict axial pull-out force of cortical screws in human tibial cortical bone

Screws are the most frequently used implants for treatment of bone fractures and play an essential role in determining fixation stability. Robust prediction of the bone-screw interface failure would enable development of improved fixation strategies and implant designs, ultimately reducing failure rates and improving outcomes of bone fracture treatments. This study aimed to compare the accuracy of micro-computed tomography image based bone volume measures, linear micro-finite element (FE) and non-linear micro-FE simulations in predicting pull-out force of 3.5 mm screws in human cadaveric tibial cortical bone. Axial pull-out experiments were performed in forty samples harvested from a single human tibia to measure ultimate force, which was correlated with bone volume around the screw and the predictions by both linear micro-FE and non-linear explicit micro-FE models. Correlation strength was similar for bone volume around the screw (R² = 0.866) and linear micro-FE (R² = 0.861), but the explicit non-linear micro-FE models were able to capture the experimental results more accurately (R² = 0.913) and quantitatively correctly. Therefore, this technique may have potential for future in silico studies aiming at implant design optimization.

Assessing the biomechanical properties of nitinol staples in normal, osteopenic and osteoporotic bone models: A finite element analysis

OBJECTIVE

Bone staples are internal fixation devices that are frequently used in the foot, ankle, and hand to provide stabilization. Fixation stability is vital after fusion or fracture surgeries to ensure proper bone healing. Patients undergoing surgeries that require fixation to keep bones aligned and stable may present with diminishing bone mechanical properties, and this may compromise the ability of the fixation hardware to maintain a stable construct. The purpose of this study was to investigate the mechanical performance of shape memory and superelastic nitinol bone staples with different bridge geometries in normal, osteopenic, and osteoporotic bone models. Contact forces and maximum principal stress and strain in the bone were recorded.

METHODS

Finite element simulations of a bone staple fixation procedure were performed to examine the initial and post-surgery contact force, as well as the maximum principal stress and strain of 15 mm bridge and 20 mm bridge staple-bone constructs.

RESULTS

Shape memory nitinol staples exhibited higher contact forces compared to superelastic nitinol staples. Nitinol bone staples with 20 mm bridge lengths displayed higher contact forces and lower stresses in all bone types, as well as lower strains in osteoporotic bone models compared to nitinol staples with a 15 mm bridge length.

CONCLUSION

Nitinol bone staple constructs with 20 mm bridge length staples provide higher contact forces and display lower stresses in the bone than 15 mm bridge staple-bone constructs, which may be beneficial in bone with diminishing mechanical properties. Both superelastic and shape memory effect nitinol staples provide adequate compression and stress relief. However, if osteopenia is present, shape memory effect nitinol staples with a 20 mm bridge length may provide more stress relief and compression, if the bone anatomy allows.

Personalised high tibial osteotomy has mechanical safety equivalent to generic device in a case-control in silico clinical trial

Background

Despite favourable outcomes relatively few surgeons offer high tibial osteotomy (HTO) as a treatment option for early knee osteoarthritis, mainly due to the difficulty of achieving planned correction and reported soft tissue irritation around the plate used to stablise the osteotomy. To compare the mechanical safety of a new personalised 3D printed high tibial osteotomy (HTO) device, created to overcome these issues, with an existing generic device, a case-control in silico virtual clinical trial was conducted.

Methods

Twenty-eight knee osteoarthritis patients underwent computed tomography (CT) scanning to create a virtual cohort; the cohort was duplicated to form two arms, Generic and Personalised, on which virtual HTO was performed. Finite element analysis was performed to calculate the stresses in the plates arising from simulated physiological activities at three healing stages. The odds ratio indicative of the relative risk of fatigue failure of the HTO plates between the personalised and generic arms was obtained from a multi-level logistic model.

Results

Here we show, at 12 weeks post-surgery, the odds ratio indicative of the relative risk of fatigue failure was 0.14 (95%CI 0.01 to 2.73, p = 0.20).

Conclusions

This novel (to the best of our knowledge) in silico trial, comparing the mechanical safety of a new personalised 3D printed high tibial osteotomy device with an existing generic device, shows that there is no increased risk of failure for the new personalised design compared to the existing generic commonly used device. Personalised high tibial osteotomy can overcome the main technical barriers for this type of surgery, our findings support the case for using this technology for treating early knee osteoarthritis.

Comparison between Pin Fixation and Combined Screw Fixation in Proximal Chevron Metatarsal Osteotomy for Hallux Valgus Deformity Correction

Background

Problems associated with hallux valgus deformity correction using Kirschner-wire (K-wire) fixation include pin pullout and loss of stability. These complications are pronounced in the osteopenic bone, and few reports have focused on pin versus screw fixation. We examined the use of additional screw fixation to avoid these problems. The aim of this study was to compare outcomes of K-wire fixation (KW) and a combined K-wire and screw fixation (KWS).

Methods

Two groups with hallux valgus deformity, who were treated with a proximal chevron metatarsal osteotomy (PCMO), were compared based on the fixation method used. The KW group included 117 feet of 98 patients, and the KWS group included 56 feet of 40 patients. Clinically, the preoperative and final follow-up visual analog scale (VAS) pain score, American Orthopedic Foot & Ankle Society (AOFAS) hallux score, and patient satisfaction score were evaluated. Radiographically, hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured.

Results

The mean VAS score decreased from 6.3 preoperatively to 1.6 postoperatively in the KW group and from 5.7 preoperatively to 0.5 postoperatively in the KWS group (p < 0.001). The mean AOFAS scores of the KW and KWS groups improved from 59.4 and 58.2, respectively, to 88.9 and 95.3, respectively (p < 0.001). Eighty-five percent in the KW group and 93% in the KWS group were satisfied with surgery. Clinical differences were not significant. The mean HVAs decreased from 34.7° to 9.1° in the KW group and from 38.5° to 9.2° in the KWS group (p < 0.001). The mean IMA decreased from 14.5° (range, 11.8°–17.2°) to 6.4° (range, 2.7°–10.1°) in the KW group and from 18.0° (range, 14.8°–21.2°) to 5.3° (range, 2.5°–8.1°) in the KWS group (p < 0.001). When IMA values at the 3-month postoperative and the final follow-up were compared, the IMA was significantly increased only in the KW group (p < 0.001) and no difference was found in the KWS group (p = 0.280).

Conclusions

We found a statistically significant difference in the decrease in IMA between the 2 groups. We recommend the combined pin and screw fixation in PCMO to enhance fixation stability and prevent potential hallux valgus correction loss.

Minimally invasive posterior locked compression plate osteosynthesis shows excellent results in elderly patients with fragility fractures of the pelvis

Purpose

Fragility fractures of the pelvis (FFP) are common in older patients. We evaluated the clinical outcome of using a minimally invasive posterior locked compression plate (MIPLCP) as therapeutic alternative.

Methods

53 Patients with insufficiency fractures of the posterior pelvic ring were treated with MIPLCP when suffering from persistent pain and immobility under conservative treatment.

After initial X-ray, CT-scans of the pelvis were performed. In some cases an MRI was also performed to detect occult fractures. Postoperatively patients underwent conventional X-ray controls. Data were retrospectively analyzed for surgical and radiation time, complication rate, clinical outcome and compared to the literature.

Results

Patients (average age 79.1 years) underwent surgery with operation time of 52.3 min (SD 13.9), intra-operative X-ray time of 9.42 s (SD 9.6), mean dose length product of 70.1 mGycm (SD 57.9) and a mean hospital stay of 21.2 days (SD 7.7).

13% patients (n = 7) showed surgery-related complications, such as wound infection, prolonged wound secretion, irritation of the sacral root or clinically inapparent screw malpositioning. 17% (n = 9) showed postoperative complications (one patient died due to pneumonia 24 days after surgery, eight patients developed urinal tract infections).

42 patients managed to return to previous living situation. 34 were followed-up after a mean period of 31.5 (6–90) months and pain level at post-hospital examination of 2.4 (VAS) with an IOWA Pelvic Score of 85.6 (55–99).

Conclusion

We showed that MIPLCP osteosynthesis is a safe surgical alternative in patients with FFP 3 and FFP 4. This treatment is another way of maintaining a high level of stability in the osteoporotic pelvic ring with a relatively low complication rate, low radiation and moderate operation time and a good functional outcome.

Resveratrol can enhance osteogenic differentiation and mitochondrial biogenesis from human periosteum-derived mesenchymal stem cells

Background

Osteoporosis is a metabolic bone disorder that leads to low bone mass and microstructural deterioration of bone tissue and increases bone fractures. Resveratrol, a natural polyphenol compound, has pleiotropic effects including anti-oxidative, anti-aging, and anti-cancer effects. Resveratrol also has roles in increasing osteogenesis and in upregulating mitochondrial biogenesis of bone marrow-derived mesenchymal stem cells (BM-MSCs). However, it is still unclear that resveratrol can enhance osteogenic differentiation or mitochondrial biogenesis of periosteum-derived MSCs (PO-MSCs), which play key roles in bone tissue maintenance and fracture healing. Thus, in order to test a possible preventive or therapeutic effect of resveratrol on osteoporosis, this study investigated the effects of resveratrol treatments on osteogenic differentiation and mitochondrial biogenesis of PO-MSCs.

Methods

The optimal doses of resveratrol treatment on PO-MSCs were determined by cell proliferation and viability assays. Osteogenic differentiation of PO-MSCs under resveratrol treatment was assessed by alkaline phosphatase activities (ALP, an early biomarker of osteogenesis) as well as by extracellular calcium deposit levels (a late biomarker). Mitochondrial biogenesis during osteogenic differentiation of PO-MSCs was measured by quantifying both mitochondrial mass and mitochondrial DNA (mtDNA) contents.

Results

Resveratrol treatments above 10 μM seem to have negative effects on cell proliferation and viability of PO-MSCs. Resveratrol treatment (at 5 μM) on PO-MSCs during osteogenic differentiation increased both ALP activities and calcium deposits compared to untreated control groups, demonstrating an enhancing effect of resveratrol on osteogenesis. In addition, resveratrol treatment (at 5 μM) during osteogenic differentiation of PO-MSCs increased both mitochondrial mass and mtDNA copy numbers, indicating that resveratrol can bolster mitochondrial biogenesis in the process of PO-MSC osteogenic differentiation.

Conclusion

Taken together, the findings of this study describe the roles of resveratrol in promoting osteogenesis and mitochondrial biogenesis of human PO-MSCs suggesting a possible application of resveratrol as a supplement for osteoporosis and/or osteoporotic fractures.

Complications after operatively treated distal radius fractures

In the recent years, treatment of distal radius fractures (DRF) has advanced considerably. Surgical fixation with palmar angular stable plate has gained popularity, due to a reported lower complication rate when compared to dorsal fixation. The type of trauma or injury, surgical procedure and impaired bone quality are all contributors to complications in DRF. The main aim of this review is to summarize the most common complications and possible therapeutic solutions. In addition, strategies for minimizing these complications will be discussed.

Early versus delayed weight bearing after surgical fixation of distal femur fractures: a non-randomized comparative study

Distal femur fractures are rare injuries with a bimodal distribution (high-energy injury in young males and low-energy fragility fractures in old females). Their management can be challenging: open reduction and internal fixation (ORIF) with distal femur locking plates is a commonly performed procedure especially in comminuted fractures with articular involvement. Anxiety regarding the stability of the fixation, especially in osteoporotic bone, leads to post-operative restrictive instructions with limitations regarding the weight-bearing status. Early weight bearing (EWB), however, was shown to enhance bone healing and was not correlated with an increased risk of fracture displacement or implant failure in previous published studies, which reported the results of proximal femur, tibia and ankle fractures surgical treatment. The current study analysed the results of a series of distal femur fractures (51 patients, mean age 64.3 ± 20.7) all treated with ORIF in a level-I major trauma centre, but differently rehabilitated. Group A was, in fact, instructed not to weight bear or to touch weight bear, while group B started to weight bear soon after surgery without specific restrictions. The objective was to compare the outcome and the complication rate in the two groups at 6 and 12 weeks after surgery. The results showed no statistically significant differences in the two groups and no post-operative complications in the EWB group. Six complications were observed in the non-weight-bearing group (four fractures displacement and two implants failure at 12-week follow-up). Distal femur fractures treated with locking plates can be rehabilitated with EWB to allow early return to function. There is no evidence that EWB increases the risk of fracture displacement or implant failure in distal femur fractures treated with distal locking plates. Instead, it is possible that post-operative non-weight-bearing status delays the fracture-healing process increasing the risk of failure of the fixation.

Cortical thickness analysis of the proximal humerus

BACKGROUND

Structural changes within the proximal humerus influence the mechanical properties of the entire bone and predispose to low-energy fractures with complex patterns. The aim of the present study was to measure the cortical thickness in different regions of the proximal humerus.

METHODS

Thirty-seven proximal humeri were analyzed using novel engineering software to determine cortical thickness in 10 distinct anatomical zones.

RESULTS

The cortical thickness values ranged from 0.33 mm to 3.5 mm. Fifteen specimens demonstrated a consistent pattern of progressive cortical thinning that increased between the bicipital groove (thickest), the lesser tuberosity and the greater tuberosity (thinnest). Fifteen humeri were characterized by a progressive increase in cortical thickness between the greater tuberosity (thinnest), the bicipital groove and lesser tuberosity (thickest). The diaphysis exhibited the thickest cortical zone in 27 specimens, whereas the articular surface possessed the thinnest cortex in 18 cases.

CONCLUSIONS

In conclusion, this is the first study to comprehensively assess cortical thickness of the humeral head. Our findings suggest that proximal humeral fractures occur along lines of cortical thinning and are displaced by the hard glenoid bone. The identification of specific areas of thick cortices may improve pre-operative planning and optimize fracture fixation.

Bioinspired polydopamine and polyphenol tannic acid functionalized titanium suppress osteoclast differentiation: a facile and efficient strategy to regulate osteoclast activity at bone-implant interface

Osseointegration of metallic implants in porous osteoporotic bone remains a challenge. Surface modification of implants to reduce peri-implant osteoclastic bone resorption was explored in the study. Bioinspired polydopamine (pDOP) and polyphenol tannic acid (pTAN) are nature-derived universal coating systems that have emerged either as a sole coating or ad-layer for biomolecular conjugation on different biomaterials. The effects pDOP and pTAN on osteoclast development have not been reported before. In this study, osteoclast development was investigated on titanium (Ti) substrates coated with pDOP (Ti-pDOP) and pTAN (Ti-pTAN). The results showed that Ti-pDOP and Ti-pTAN coating reduced tartrate-resistant acid phosphatase activity and osteoclast cell number as compared with pristine Ti. Intriguingly, the reduction was higher on Ti-pTAN than on Ti-pDOP. Economical and biocompatible tannic acid serves as a superior coating in decreasing osteoclast activity when compared with that of pDOP coating and could be used to modulate osteoclast activity at bone-implant interfaces.

The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates: An experimental and finite element study

Objectives

Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure.

Materials and Methods

A 10° opening wedge HTO was created in a composite tibia. Imaging and strain gauge data were used to create and validate FE models. Models of an intact tibia and a tibia implanted with a custom HTO plate using two different bridging spans were validated against experimental data. Physiological muscle forces and different stages of osteotomy gap healing simulating up to six weeks postoperatively were then incorporated. Predictions of plate stress and IFM for the custom plate were compared against predictions for an industry standard plate (TomoFix).

Results

For both plate types, long spans increased IFM but did not substantially alter peak plate stress. The custom plate increased axial and shear IFM values by up to 24% and 47%, respectively, compared with the TomoFix. In all cases, a callus stiffness of 528 MPa was required to reduce plate stress below the fatigue strength of titanium alloy.

Conclusion

We demonstrate that larger bridging spans in opening wedge HTO increase IFM without substantially increasing plate stress. The results indicate, however, that callus healing is required to prevent fatigue failure.

Cite this article: A. R. MacLeod, G. Serrancoli, B. J. Fregly, A. D. Toms, H. S. Gill. The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates: An experimental and finite element study. Bone Joint Res 2018;7:639–649. DOI: 10.1302/2046-3758.712.BJR-2018-0035.R1.

Cement Augmentation of Dynamic Hip Screw to Prevent Screw Cut Out in Osteoporotic Patients with Intertrochanteric Fractures: A Case Series

Purpose

The purpose of this study is to describe a method of inserting cement in the femoral head before fixation with dynamic hip screw to prevent screw cut out due to osteoporosis and to evaluate its clinical outcome in these patients.

Materials and Methods

In this prospective study, 30 patients aged 60 years and older with intertrochanteric fracture were included. Bone mineral density was measured. After reaming of the femoral head and neck with a triple reamer and polymethyl methacrylate, bone cement was introduced into the femoral head using a customized nozzle and a barrel fitted on a cement gun. A Richard screw was inserted and the plate was fixed over the femoral shaft. Patients were mobilized and clinical outcomes were rated using the Salvati and Wilson's scoring system.

Results

More patients included in this study were between 66 and 70 years old than any other age group. The most common fracture according to the Orthopaedic Trauma Association classification was type 31A2.2 (46.7%). The T-score was found to be −2.506±0.22 (mean±standard deviation); all patients were within the range of −2.0 to −2.8. The duration of radiological union was 13.67±1.77 weeks. Salvati and Wilson's scoring at 12 months of follow up was 30.96±4.97. The majority of patients were able to perform their normal routine activities; none experienced implant failure or screw cut out.

Conclusion

Bone cement augmentation may effectively prevent osteoporosis-related hardware complications like screw cut out in elderly patients experiencing intertrochanteric fractures.

Optimization of Taylor spatial frame half-pins diameter for bone deformity correction: Application to femur

Using external fixtures for bone deformity correction takes advantages of less soft tissue injury, better bone alignment and enhances strain development for bone formation on cutting section, which cause shorter healing time. Among these fixtures, Taylor spatial frame is widely used and includes two rings and six adjustable struts developing 6 degrees of freedom, making them very flexible for this type of application. The current study describes a method to optimize Taylor spatial frame pin-sizes currently chosen from the surgeon's experiences. A three-dimensional model of femur was created from computed tomography images; segmentation of the medical images was made based on the Hounsfield unit (gray scale) in order to allocate adequate mechanical properties into cortical and trabecular bone sections. Both the cortical and trabecular sections were assumed to be isotropic and homogeneous. The diameter optimization of Taylor spatial frame's half-pins was carried out by coupling genetic algorithm and finite element analysis. The finite element analysis was based on a static mechanical load corresponding to a standing person's body weight. Finite element analysis results were validated with experimentally measured strains obtained from bone compression tests. A cost function, based on the developed bone stresses, was defined close to the Taylor spatial frame's half-pins. The calculated cost function showed a decrease of over 33% from the initial half-pin selection by the surgeon and the genetic algorithm optimization. Consequently, the maximum stresses experienced by the bone in the connected location of the half-pins decreased from 121.4 MPa in the surgeon's selection to 73.07 MPa as a result of the optimization process.

Virtual guidance versus virtual implant planning system in the treatment of distal radius fractures

BACKGROUND

A virtual guidance framework is used to assist the conventional method of virtual implant planning system (VIPS). The study null hypothesis was that its screw placement accuracy is equal to that of conventional VIPS.

METHODS

In 34 distal radius sawbone models, 3D implant planning was performed. A camera attached to the surgical drill was used to support screw positioning. Differences of angles/tip distances between planned and placed screws were identified in intraoperative cone beam Computer tomography (CT) and compared with already existing data from 22 patients treated by conventional VIPS.

RESULTS

The virtual guidance group showed tip distances of 1.02 ± 0.56 mm, azimuth of 3.69° ± 4.34°, and inclination of 1.75° ± 1.37°, whereas the VIPS group showed tip distances of 2.23 ± 0.99 mm (P < 0.001), azimuth of 23.17° ± 33.50° (P < 0.001), and inclination angle of 4.18° ± 6.29° (P = 0.001).

CONCLUSIONS

The results reveal that using a guidance framework leads to a higher accuracy in screw placement compared with the conventional VIPS itself.

Hybrid fracture fixation systems developed for orthopaedic applications: A general review

Orthopaedic implants are applied daily in our orthopaedic clinics for treatment of musculoskeletal injuries, especially for bone fracture fixation. To realise the multiple functions of orthopaedic implants, hybrid system that contains several different materials or parts have also been designed for application, such as prosthesis for total hip arthroplasty. Fixation of osteoporotic fracture is challenging as the current metal implants made of stainless steel or titanium that are rather rigid and bioinert, which are not favourable for enhancing fracture healing and subsequent remodelling. Magnesium (Mg) and its alloys are reported to possess good biocompatibility, biodegradability and osteopromotive effects during its in vivo degradation and now tested as a new generation of degradable metallic biomaterials. Several recent clinical studies reported the Mg-based screws for bone fixation, although the history of testing Mg as fixation implant was documented more than 100 years ago. Truthfully, Mg has its limitations as fixation implant, especially when applied at load-bearing sites because of rather rapid degradation. Currently developed Mg-based implants have only been designed for application at less or non-loading-bearing skeletal site(s). Therefore, after years research and development, the authors propose an innovative hybrid fixation system with parts composed of Mg and titanium or stainless steel to maximise the biological benefits of Mg; titanium or stainless steel in this hybrid system can provide enough mechanical support for fractures at load-bearing site(s) while Mg promotes the fracture healing through novel mechanisms during its degradation, especially in patients with osteoporosis and other metabolic disorders that are unfavourable conditions for fracture healing. This hybrid fixation strategy is designed to effectively enhance the osteoporotic fracture healing and may potentially also reduce the refracture rate. The translational potential of this article: This article systemically reviewed the combination utility of different metallic implants in orthopaedic applications. It will do great contribution to the further development of internal orthopaedic implants for fracture fixation. Meanwhile, it also introduced a titanium-magnesium hybrid fixation system as an alternative fixation strategy, especially for osteoporotic patients.

An innovative Mg/Ti hybrid fixation system developed for fracture fixation and healing enhancement at load-bearing skeletal site

Magnesium (Mg) is a potential biomaterial suitable for developing biodegradable orthopaedic implants, especially as internal fixators for fracture fixation at non-load bearing skeletal sites. However, Mg alone cannot provide sufficient mechanical support for stable fracture fixation at load bearing sites due to its rapid degradation in the early stage after implantation. In consideration of the strengths and weaknesses of Mg, we developed an innovative magnesium/titanium (Mg/Ti) hybrid fixation system for long bone fracture fixation and investigated the fixation efficacy. The finite element analysis (FEA) results indicated that the Mg/Ti hybrid fixation system provided sufficient mechanical support for fracture fixation at load-bearing skeletal site. As a proof-of-concept, we performed a "Z-shaped" open osteotomy at the mid-shaft of rabbit tibia. For comparison, the animals were divided into two groups: Mg/Ti group (fixated with Mg screws and Ti fixators) and Ti control group (fixated with Ti screws and Ti fixators). The radiographic, four-point bending mechanical test, histological and histomorphometric analysis were postoperatively performed in a temporal manner up to 12 weeks. Both X-ray and micro-CT images of the Mg/Ti group showed a larger callus (14.7% at 3rd week and 24.8% at 6th week, n = 5-7, p < 0.05) in the regions of interest (ROIs) over time, especially at the opposite cortex of the fixation plate. At the 12th week post-operation, the biomechanical test result indicated that the rabbit tibia in the Mg/Ti group healed better and the overall mechanical strength was approximately 3-fold higher (n = 8, p < 0.05) than that at 6th week. Furthermore, the FEA revealed that the Mg/Ti group had a higher mechanical strength (19.5% at week 6 and 31.5% at week 12) at the specified ROI and resulted in an earlier and faster endochondral ossification (68.0% at week 3 and 71.4% at week 6) with a higher expression of osteocalcin (54.0%) and collagen I (34.2%) than the Ti control group (n = 4, p < 0.05). Further evaluation suggested that a higher expression of calcitonin gene-related peptide (CGRP), a known osteogenic neuron peptide, in the fracture callus of the Mg/Ti group might be a major underlying mechanism of enhanced fracture healing attributed to the release of Mg ions during the degradation of Mg screws.

Pre-operative planning for fracture fixation using locking plates: device configuration and other considerations

Most locked plating failures are due to inappropriate device configuration for the fracture pattern. Several studies cite screw positioning variables such as the number and spacing of screws as responsible for occurrences of locking plate breakage, screw loosening, and peri-prosthetic re-fracture. It is also widely accepted that inappropriate device stiffness can inhibit or delay healing. Careful preoperative planning is therefore critical if these failures are to be prevented. This study examines several variables which need to be considered when optimising a locking plate fixation device for fracture treatment including: material selection; screw placement; the effect of the fracture pattern; and the bone-plate offset. We demonstrate that device selection is not straight-forward as many of the variables influence one-another and an identically configured device can perform very differently depending upon the fracture pattern. Finally, we summarise the influence of some of the key parameters and the influence this can have on the fracture healing environment and the stresses within the plate in a flowchart.

Microstructural properties of trabecular bone autografts: comparison of men and women with and without osteoporosis

The microstructure of autologous bone grafts from men over 50 years old and postmenopausal women undergoing spinal fusion were evaluated using micro-CT. We demonstrated postmenopausal women, especially those with osteoporosis (OP) presented more serious microarchitectural deterioration of bone grafts.

PURPOSE

This study was undertaken to determine microstructural properties of cancellous bone used as autologous bone grafts from osteoporosis patients undergoing lumbar fusion by comparing microstructural indices to controls.

METHODS

Cancellous bone specimens from spinous processes were obtained from 41 postmenopausal women (osteoporosis women, n = 19; controls, n = 22) and 26 men over 50 years old (osteoporosis men, n = 8; controls, n = 18) during lumbar fusion surgery. The microstructural parameters were measured using micro-CT.

RESULTS

Significant difference in bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th), and structure model index (SMI) value existed between postmenopausal women with OP and controls. Significant difference in trabecular number (Tb.N) existed between men over 50 years old with OP and controls. Postmenopausal women exhibited lower BV/TV, Tb.Th, and higher SMI value than men over 50 years old. Postmenopausal women with OP exhibited lower BV/TV, Tb.Th, and higher BS/BV than men over 50 years old with OP.

CONCLUSIONS

Post-menopausal women and older men with OP have worse bone quality in autografts than non-osteoporotic men and women. Postmenopausal women with OP presented serious microarchitectural deterioration in older population.

Patient-specific in silico models can quantify primary implant stability in elderly human bone

Secure implant fixation is challenging in osteoporotic bone. Due to the high variability in inter- and intra-patient bone quality, ex vivo mechanical testing of implants in bone is very material- and time-consuming. Alternatively, in silico models could substantially reduce costs and speed up the design of novel implants if they had the capability to capture the intricate bone microstructure. Therefore, the aim of this study was to validate a micro-finite element model of a multi-screw fracture fixation system. Eight human cadaveric humerii were scanned using micro-CT and mechanically tested to quantify bone stiffness. Osteotomy and fracture fixation were performed, followed by mechanical testing to quantify displacements at 12 different locations on the instrumented bone. For each experimental case, a micro-finite element model was created. From the micro-finite element analyses of the intact model, the patient-specific bone tissue modulus was determined such that the simulated apparent stiffness matched the measured stiffness of the intact bone. Similarly, the tissue modulus of a small damage region around each screw was determined for the instrumented bone. For validation, all in silico models were rerun using averaged material properties, resulting in an average coefficient of determination of 0.89 ± 0.04 with a slope of 0.93 ± 0.19 and a mean absolute error of 43 ± 10 μm when correlating in silico marker displacements with the ex vivo test. In conclusion, we validated a patient-specific computer model of an entire organ bone-implant system at the tissue-level at high resolution with excellent overall accuracy. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:954-962, 2018.

Optimization of screw fixation in rat bone with extracorporeal shock waves

Screw fixation in osteoporotic patients is becoming an increasing problem in orthopaedic surgery as deterioration of cortical and cancellous bone hamper biomechanical stability and screw fixation. This might result in delayed weight-bearing or failure of instrumentation. We hypothesized that local peri-operative shock wave treatment can optimize osseointegration and subsequent screw fixation. In eight female Wistar rats, two cancellous and two cortical bone screws were implanted in both femora and tibiae. Immediately after implantation, 3.000 unfocused extracorporeal shock waves (energy flux density 0.3 mJ/mm² ) were applied to one side. The other side served as non-treated internal control. Evaluation of osseointegration was performed after 4 weeks with the use of microCT scanning, histology with fluorochrome labeling, and pull-out tests of the screws. Four weeks after extracorporeal shock wave treatment, treated legs exhibited increased bone formation and screw fixation around cortical screws as compared to the control legs. This was corroborated by an increased pull-out of the shock wave treated cortical screws. The cancellous bone screws appeared not to be sensitive for shock wave treatment. Formation of neocortices after shock wave therapy was observed in three of eight animals. Furthermore, de novo bone formation in the bone marrow was observed in some animals. The current study showed bone formation and improved screw fixation as a result of shock wave therapy. New bone was also formed at locations remote from the screws, hence, not contributing to screw fixation. Further, research is warranted to make shock wave therapy tailor-made for fracture fixation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:76-84, 2018.

Surgical treatment of osteoporotic fractures: An update on the principles of management

The treatment of osteoporotic fractures continues to challenge orthopedic surgeon. The fragility of the underlying bone in conjunction with the need for specific implants led to the development of explicit surgical techniques in order to minimize implant failure related complications, morbidity and mortality. From the patient's perspective, the existence of frailty, dementia and other medical related co-morbidities induce a complex situation necessitating high vigilance during the perioperative and post-operative period. This update reviews current principles and techniques essential to successful surgical treatment of these injuries.

Long-term Results of Intercalary Endoprosthetic Short Segment Fixation Following Extended Diaphysectomy

Intercalary endoprosthetic reconstruction following diaphyseal resection of osseous tumors offers functional advantages through preservation of native joints adjacent to the resected defect. Use of such implants is restricted by the amount of bone available for stem fixation adjacent to the defect. This study aimed to determine whether short osseous segment fixation with acceptable outcomes and complication rate can be reliably achieved with a customized intercalary endoprosthesis following extended diaphysectomy. A retrospective review of prospectively collected data was performed on 6 patients receiving customized anchor plugs for short segment fixation with a double compressive osseointegration intercalary implant to reconstruct segmental defects. Five of the implants were augmented with cement to support fixation in metaphyseal bone. Patient age at surgery ranged from 12 to 86 years. At mean follow-up of 39 months, mean Musculoskeletal Tumor Society functional score was 26.3, with 5 of 6 patients achieving scores of 27 or greater. Stable fixation was achieved in all patients, with the shortest segment of bone 3.7 cm in length. Three mechanical implant failures requiring revision surgery occurred. No patient required revision of the entire implant, secondary adjacent joint replacement, or secondary amputation. No patient exhibited aseptic loosening, and no case was complicated by infection. Excellent functional outcomes were seen with follow-up out to 9 years. This suggests that cement-augmented double compressive osseointegration intercalary endoprosthetic reconstruction can extend the benefits of intercalary replacement to many patients who otherwise might require adjacent joint or physeal sacrifice. However, patients should be counseled on the high risk of implant failure with subsequent need for revision surgery. [Orthopedics. 2017; 40(6):e964-e970.].

Do osteoporotic fractures constitute a greater recalcitrant challenge for skeletal regeneration? Investigating the efficacy of BMP-7 and zoledronate treatment of diaphyseal fractures in an open fracture osteoporotic rat model

Osteoporotic fractures may pose a challenge for skeletal regeneration. This study investigates if pharmaceutical interventions such as bone morphogenetic protein 7 (BMP-7) alone or in combination with Zoledronate have equivalent efficacy in osteoporotic bone? Our findings suggest they do and that an osteoporotic bone environment may increase sensitivity to BMP-7.

INTRODUCTION

Osteoporosis is thought to contribute to delayed or impaired bone healing. Bone morphogenetic protein 7 (BMP-7) alone or synergistically combined with zoledronate (ZA) has proven effective in augmenting the regenerative response in healthy young male rats. Yet their comparative efficacy in an osteoporotic bone environment is unknown. Our study aimed to answer the following questions using the ovariectomized (OVX) rat model of osteoporosis: Do osteoporotic fractures pose a greater challenge for skeletal regeneration? Are interventions with BMP-7-alone or combined with ZA of equivalent efficacy in osteoporotic bone?

METHODS

Sham operations (n = 33) or ovariectomies (n = 34) were performed in 12-week-old female Sprague-Dawley rats. Mid-diaphyseal open femoral osteotomies were created at 24 weeks of age and the rats allocated to either (i) untreated, (ii) BMP-7-only or (iii) BMP-7 + ZA treatment groups. At 6 weeks post-osteotomy, fracture healing was evaluated by radiography, μCT and 3-point bending mechanical tests.

RESULTS

Cumulatively, radiological, micro-structural and mechanical measures were equivalent in both healthy and osteoporotic environments. A reduced response to BMP-7-alone was observed in healthy rats that may be age/gender- or protocol/fracture-model dependent. Conversely, the BMP-7-only treated OVX group attained 100 % union in addition to significantly increased measures of mineralized bone volume, total callus volume, peak force and absorbed energy relative to untreated OVX fractures.

CONCLUSIONS

Our findings refute the hypothesis that osteoporotic fractures constitute a greater recalcitrant challenge for skeletal regeneration. Furthermore, our results suggest that an oestrogen-deficient environment may in fact cause an increased sensitivity to BMP-7.

Age-related optimization of screw placement for reduced loosening risk in locked plating

When using locked plating for bone fracture fixation, screw loosening is reported as one of the most frequent complications and is commonly attributed to an incorrect choice of screw configuration. Choosing a patient-optimized screw configuration is not straightforward as there are many interdependent variables that affect device performance. The aim of the study was to evaluate the influence that locking screw configuration has on loosening risk and how this is influenced by bone quality. This study uses finite element models that incorporate cortical bone heterogeneity, orthotropy, and geometrical nonlinearity to examine the effect of screw configuration on variables associated with loosening and interfragmentary motion. Strain levels within the bone were used as indicators of regions that may undergo loosening. The study found that, in healthy bone under axial loading, the most important variables influencing strain levels within the bone were the size of the bridging span (working length) and the plate rigidity. Unlike healthy bone, osteoporotic bone was found to be particularly sensitive to the spacing of the screws within the plate. Using two empty screw holes between the screws closest to the fracture was found to reduce the strain levels at the first screw by 49% in osteoporotic bone (compared to only 2.4% in healthy bone). The study also found that under torsional loading the total number of screws used was the most important variable with a 59% reduction in the strain around the screws closest to the fracture when using six rather than four screws in osteoporotic bone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1856-1864, 2016.

Distal Femoral Replacement for Acute Distal Femoral Fractures in Elderly Patients

OBJECTIVES

To evaluate outcomes and complications using cemented modular distal femoral replacement in elderly patients with distal femoral fractures.

DESIGN

Retrospective chart review, case series.

SETTING

A Level 1 and Level 2 trauma center, both tertiary referral hospitals.

PATIENTS/PARTICIPANTS

Eighteen patients older than 60 years (average age 77 years) who had cemented distal femoral replacement for distal femoral fractures (comminuted, intraarticular, osteoporotic, arthritic) between 2005 and 2013. Patients with previous knee surgery were excluded.

INTERVENTION

Cemented modular distal femoral replacement.

MAIN OUTCOME MEASURES

Implant status, complications, Knee Society Score, Musculoskeletal Tumor Society score, and Western Ontario and McMaster Osteoarthritis Index.

RESULTS

All patients were extremely or very satisfied with their outcomes. For patients with functional outcome data, Knee Society Score averaged 85.7 with a functional score of 35, Musculoskeletal Tumor Society score averaged 19.2, and Western Ontario and McMaster Osteoarthritis Index score averaged 23.1 at an average follow-up of 2.3 years. Range of motion was 1-99 degrees. Implant-related complications occurred in 2 patients (11%); one required revision to total femoral replacement because of periprosthetic fracture and the other had a deep infection that required exchange of the components. No patient had aseptic loosening or patellar maltracking. There were no perioperative deaths or late amputations.

CONCLUSIONS

Cemented modular distal femoral replacement is a viable treatment option in elderly patients that permits immediate full weight-bearing, with most patients returning to preoperative functional status.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcome Analysis of Locking Plate Fixation in Proximal Humerus Fracture

INTRODUCTION

Proximal humerus fractures account for approximately 5% of all fractures. Stable minimally displaced fractures can be treated nonoperatively but the management of displaced fractures remain controversial with various modalities of treatment available. Locking plates provide stable fixation and enable early postoperative mobilization specially in osteoporotic proximal humerus fracture.

AIM

To evaluate the functional outcome of locking plate fixation and to compare the results of two approaches used for fixation.

MATERIALS AND METHODS

This prospective study was conducted at a tertiary level hospital between September 2011 to December 2013. PHILOS plates were used for internal fixation of displaced proximal humerus fractures Neer's type 2 part, 3 part and 4 part fractures on 26 patients (M/F ratio 1.36:1; mean age 46 years). According to Neer classification, 5,12 and 9 patients had displaced 2, 3 and 4 part fractures respectively. Deltopectoral and deltoid splitting approaches were used for fixation on 13 patients each. Functional outcome was assessed using Constant-Murley shoulder score. Graphpad software version 6.0 was used with Chi-square test and Fisher-exact test are used to compare data. The p-value< 0.05 is considered significant.

RESULTS

Of the 26 patients, all fractures united radiologically and clinically and average constant score at final follow-up was 72.5. At the final follow-up 8 patients had good score, 10 patients had moderate score, 6 patients had excellent outcome and 2 patients had poor outcome according to Constant score. Mean time to union was 12.3 weeks (9 -15 weeks). Four complications (15.4%) were encountered, 2 cases of varus malunion, 1 case of wound infection which required wound debridement and 1 case of screw cut-out in which screw removal was done. Mean constant score in delto splitting approach was 70.9 and 74 in deltopectoral group (p-value= 0.54). No significant difference existed in constant score in 2 approaches. No significant difference existed between groups in terms of complications (P > .05) and all fractures were united.

CONCLUSION

Our study demonstrates that locking plate fixation gives good functional outcomes in treatment of proximal humerus fractures. There was no significant difference in the two approaches used for exposure. Our results are comparable to various studies conducted by other authors which states that locking plates provide better functional and radiological outcomes as compared to other fixation methods like Tension band wiring, percutaneous K-wire fixation, non-locking plates, intramedullary nails.

Sacroplasty procedural extravasation with high viscosity bone cement: comparing the intraoperative long-axis versus short-axis techniques in osteoporotic cadavers

INTRODUCTION

Percutaneous sacroplasty involves image-guided injection of bone cement for sacral insufficiency fractures to alleviate pain and facilitate mobility. Correct sacral placement of the cement and the risk of cement extravasation present procedural challenges. This study compares the occurrence, number, location, and surface area of high viscosity radiopaque bone cement extravasation via biplane fluoroscopy with Dyna CT between the fluoroscopically-guided intraoperative long-axis and short-axis sacroplasty techniques in osteoporotic cadavers.

METHODS

Ten osteoporotic cadavers underwent bilateral percutaneous instillation of VertaPlex HV High Viscosity Radiopaque Bone Cement. Long- and short-axis sacroplasty techniques were randomly assigned to zone 1 of the left or right sacral ala of each cadaver. Cement extravasation data were summarized by technique (long-axis vs short-axis) and time period (15-min and 3-hour post-procedure syngo DynaCT scan) in the form of point and CI estimates for the true proportions of cement extravasation.

RESULTS

No procedural sacral extravasation differences were observed between the long-axis and short-axis sacroplasty techniques. There were no occurrences of intra-procedural or post-procedural cement extravasation at 15 min or 3 hours in association with either the long-axis sacroplasty technique or the short-axis sacroplasty technique.

CONCLUSIONS

The long- and short-axis sacroplasty techniques, using high viscosity cement with careful post-procedural positioning, result in no occurrence of cement extravasation in porous osteoporotic cadaver bone.

Ovariectomy-Induced Osteopenia Influences the Middle and Late Periods of Bone Healing in a Mouse Femoral Osteotomy Model

OBJECTIVE

It is known that bone healing is delayed in the presence of osteoporosis in humans. However, due to the complexities of the healing of osteoporotic fractures, animal models may be more appropriate for studying the effects of osteoporosis in more detail and for testing drugs on the fracture repair process. The purpose of this study was to investigate the influence of ovariectomy-induced osteopenia in bone healing in an open femoral osteotomy model, and to test the feasibility of this model for evaluating the healing process under osteopenic conditions.

METHODS

Ovariectomized (OVX) mouse models were employed to assess the effects of osteopenia on fracture healing, A mid-shaft femur osteotomy model was also established 3 weeks after ovariectomy as an osteopenic fracture group (OVX group). Femurs were then harvested at 2 weeks and 6 weeks after fracture for X-ray radiography, micro-computed tomography (micro-CT), histology, and biomechanical analysis. A sham-operated group (sham group) was used for comparison.

RESULTS

The OVX mice had significantly lower bone volume density (BVF), volumetric bone mineral density (vBMD), and tissue mineral density (TMD) in the fracture calluses at 6 weeks (p<0.05), and similar trend was observed in 2 weeks. Additionally, larger calluses in OVX animals were observed via micro-CT and X-ray, but these did not result in better healing outcomes, as determined by biomechanical test at 6 weeks. Histological images of the healing fractures in the OVX mice found hastening of broken end resorption and delay of hard callus remodeling. The impaired biomechanical measurements in the OVX group (p<0.05) were consistent with micro-CT measurements and radiographic scoring, which also indicated delay in fracture healing of the OVX group.

CONCLUSIONS

This study provided evidence that ovariectomy-induced osteopenia impair the middle and late bone healing process. These data also supported the validity of the mouse femoral osteotomy model in evaluating the process of bone healing under osteopenic conditions.

Failure of fracture fixation in osteoporotic bone

This manuscript will provide an overview of how the age and osteoporosis related changes in mechanical properties of bone affect the stability of osteosynthesis constructs, both from a mechanical as well as from a clinical perspective. The manuscript will also address some of the principles of fracture fixation for osteoporotic fractures and discuss applications of osteoporotic fracture fixation at sites typically affected by fragility fractures, namely the distal radius, the proximal humerus, the femur and the spine. The primary aim of operative treatment in elderly individuals is the avoidance of immobilization of the patient. In selected cases conservative treatment might be required. Generally, choice of treatment should be individualized and based on the evaluation of patient-specific, fracture-specific and surgeon-specific aspects. The orthopaedic surgeon plays an essential role in enabling functional recovery by providing good surgery but a multidisciplinary approach is essential in order to support the patient to regain his/her quality of life after fragility fracture. Overall, the therapy of fractures in osteoporotic bone in the elderly requires a multidisciplinary therapeutic acute care concept including treatment of co-morbidities and correct choice of timing, and technique of the operative intervention.

Osteoporosis in Cervical Spine Surgery

STUDY DESIGN

Retrospective administrative database analysis.

OBJECTIVE

To investigate the effect of osteoporosis (OS) on complications and outcomes in patients undergoing cervical spine surgery.

SUMMARY OF BACKGROUND DATA

OS is the most prevalent degenerative human bone disease, and spine surgeons will inevitably perform procedures on patients with OS. These patients might present a difficult patient cohort because many fixation techniques depend on bone quality and adequate bone healing--both of which are compromised in OS.

METHODS

The nationwide inpatient sample was queried using the Ninth Revision, Clinical Modification procedural codes for cervical spine procedures and diagnosis codes for degenerative conditions of cervical spine from 2002 to 2011. Patients were separated into two cohorts, those patients with OS and those without OS. Demographics, hospital characteristics, and adjusted complication likelihood were analyzed. Multivariate regression analysis was performed to determine odds of revision surgery in patients with OS.

RESULTS

Of all patients undergoing degenerative cervical spine surgery, 2% were identified as having OS (32,557 of a sample of 1,602,129 patients). Osteoporotic patients were more likely to undergo posterior cervical spine fusion when compared with those patients without OS (11.3% vs. 5.4%, P < 0.0001). Moreover, circumferential fusion was performed 3 times more frequently in the osteoporotic cohort. Adjusted complications showed increased odds for postoperative hemorrhage (odds ratio = 1.70, 95% confidence interval = 1.46-1.98, P < 0.0001). Patients with OS stayed in the hospital longer (3.5 vs. 2.5 days, P < 0.0001) and had 30% costlier hospitalizations. Multivariate for revision surgery indicated that osteoporotic patients had significantly increased odds of revision surgery (odds ratio = 1.54, P ≤ 0.0001) when referenced to non-osteoporotic patients undergoing cervical spine surgery.

CONCLUSION

Osteoporotic patients were more likely to undergo revision surgery, have longer hospitalizations, and have higher hospitalization costs, than their non-osteoporotic counterparts.

LEVEL OF EVIDENCE

3.

Time-elapsed screw insertion with microCT imaging

Time-elapsed analysis of bone is an innovative technique that uses sequential image data to analyze bone mechanics under a given loading regime. This paper presents the development of a novel device capable of performing step-wise screw insertion into excised bone specimens, within the microCT environment, whilst simultaneously recording insertion torque, compression under the screw head and rotation angle. The system is computer controlled and screw insertion is performed in incremental steps of insertion torque. A series of screw insertion tests to failure were performed (n=21) to establish a relationship between the torque at head contact and stripping torque (R(2)=0.89). The test-device was then used to perform step-wise screw insertion, stopping at intervals of 20%, 40%, 60% and 80% between screw head contact and screw stripping. Image data-sets were acquired at each of these time-points as well as at head contact and post-failure. Examination of the image data revealed the trabecular deformation as a result of increased insertion torque was restricted to within 1mm of the outer diameter of the screw thread. Minimal deformation occurred prior to the step between the 80% time-point and post-failure. The device presented has allowed, for the first time, visualization of the micro-mechanical response in the peri-implant bone with increased tightening torque. Further testing on more samples is expected to increase our understanding of the effects of increased tightening torque at the micro-structural level, and the failure mechanisms of trabeculae.