Internal fracture fixation in patients with osteoporosis

From healthy to osteoporotic: Exploring how bone quality alters implant performance in Pauwels type III fracture

Osteoporosis compromises bone strength, making bone more susceptible to fractures. Decreased bone density heightens susceptibility to femoral neck fractures. The study investigated the impact of bone density on implant performance across three categories of bone quality: healthy, osteopenic, and osteoporotic. The effectiveness of three commonly used implant types (Femoral Neck System, Dynamic Condylar Screw, and Dynamic Hip Screw, where later two equipped with an anti-rotational screw) was evaluated through finite element analysis for treating Pauwels type III fracture. The bone geometry and material properties were based on a subject-specific CT data. The density and Young's modulus of bone elements were adjusted to simulate osteopenic and osteoporotic bone. FE models were developed and the peak loading values for normal walking and stair climbing conditions were considered. Stability and performance of the implant were assessed using bone strain, implant stress, deformation and rotation of the femoral head, micromotion at the interfaces, strain shielding, and risk of implant cut-out. Except for DCS with AR-screw and FNS implants under stair climbing conditions in weaker bone qualities, the implant stress remained within the yield limit of Ti-alloy. The comprehensive assessment identified DHS2 as the preferred implant option for treating such fractures, even in poor bone quality. The risk of cut-out risk was up to 3.9% higher in DCS2 and 6.3% higher in FNS implanted models than in DHS2. The effect of change in bone quality was comparatively less in DHS2 implants than the other two types.

Open reduction, internal fixation of Vancouver B1, C & D type periprosthetic femoral fractures with use of an antiglide plate at fracture apex - The "Apex Plate"

Background

Periprosthetic femoral fractures are associated with significant morbidity, mortality, social and economic cost. The incidence of these fractures is expected to increase with an ever-growing elderly world-population. The complex nature and varied pattern of these injuries requires a range of specialized surgical techniques and tools. Fixation alone is being increasingly regarded as the preferred method of addressing these fractures, even in cases where the femoral stem is unstable, showing favourable outcomes overall when compared to a fix-and-replace approach. Lateral plate fixation is the primary surgical method for either case, and while there is a growing offer of implants specifically for this subset of orthopaedic injuries, the problem of non-union appears to be the most common of complications encountered postoperatively. We prefer fixation alone, including for Unified Classification System (UCS) B2 and B3 type fractures. A small-fragment plate fixed at the fracture apex acts as both a reduction device, thereby simplifying the operation itself, and as a buttressing device. The lateral tension-banding plate method can exploit the latter function of this smaller plate to improve the stability of the fixed construct, and thereby encourage more reliable bone healing.

Cases

We have treated 6 patients between the ages of 59 and 93 with UCS B1, B2, C and D fractures in this fashion. Fragments around an unstable stem (as with a UCS B2 or B3 fracture) were first reduced anatomically and fixed using cerclages, effectively creating a UCS B1, C or D type fracture, which can then be addressed using this two-plating system. All patients were discharged from hospital, returning home to activities of daily living. All radiographic follow-up demonstrated maintenance of reduction and implant position. For patients with radiographic follow-up beyond two months, fracture consolidation or partial consolidation was noted. No surgical infections were recorded.

Conclusions

We present this method of fixation for these types of fractures as a "mixed principles" approach to osteosynthesis. Here, the buttressing nature of the medial femoral cortex is at least in part reconstituted so that compressive forces are generated across cortices where an oblique or spiral fracture pattern would otherwise generate shear forces. Re-establishing these biomechanics with a lateral tension band plate, we assume, generates a more stable construct that favours bone healing and reduces the chances of non- or mal- union.

Fix or Replace? Comparable Outcomes With Internal Fixation and Distal Femoral Replacement for Periprosthetic Fractures Above Total Knee Arthroplasty

BACKGROUND

The optimal treatment for periprosthetic fracture (PPfx) around total knee arthroplasty (TKA) remains a topic of debate. Due to its low incidence, comparative studies analyzing arthroplasty and fixation are lacking in the literature. The purpose of this study was to compare the outcomes of distal femoral replacement (DFR) and open reduction and internal fixation open reduction internal fixation (ORIF) for distal femur PPfx.

METHODS

We reviewed a consecutive series of 99 patients who underwent DFR (n = 54) or ORIF (n = 45) for distal femur PPfx. The indications for DFR were reviewed. Fractures were classified based on their relation to the implant using the Su classification. The primary outcome was rerevision, while secondary endpoints included inpatient complications, mortality within the first year, and mechanical complications such as loosening and non-union.

RESULTS

Type 2 fractures were the most prevalent type in both groups (DFR 37 versus ORIF 48.9%), while Type 1 fractures were more commonly treated with ORIF (35.6 versus 16.7%) and Type 3 with DFR (46.3 versus 15.6%) (P = 0.003). The preferred techniques in the ORIF group were plate osteosynthesis (66.7%) and retrograde nailing (31.1%). At a mean follow-up of 4.2 years (range, one to 14.1), DFR and ORIF did not demonstrate any difference in revision rates (13 versus 24.4%, P = 0.140) or mortality (3.7 versus 4.4%, P = 0.887). However, more mechanical complications were noted in the ORIF group (22.2 versus 7.4%, P = 0.035).

CONCLUSIONS

Both DFR and open reduction and internal fixation have comparable revision rates, complications, and clinical outcomes when used in supracondylar periprosthetic distal femur fractures. Longer-term studies are needed to assess DFR survivorship as well as outcomes of newer trauma techniques such as nail-plate combinations.

Anterior Sternoclavicular Joint Dislocation Classification and Management: A Review of the Literature

» Closed reduction and physical therapy are the primary approaches for most acute anterior sternoclavicular joint (SCJ) dislocations, with acceptable outcomes for low-demand patients. However, these treatments have a high rate of recurrent instability, albeit with minimal functional impact.» Persistently symptomatic recurrent dislocations typically warrant surgical intervention. The choice of technique-ranging from nonabsorbable sutures to tendon autografts and plating-is based on individualized care by considering patient-specific factors such as activity level, bone quality, and health.» High-demand patients, such as athletes, benefit from robust techniques like suture repair with an internal brace or hamstring tendon autografts. These methods provide durable stability and reduce recurrence risks.» Patients with poor bone quality, such as those with osteoporosis, may require plating techniques (e.g., locking plates or SCJ-specific plates) to ensure rigid fixation, albeit with potential hardware-related complications.» Owing to the rarity of the condition and limited studies, no standardized treatment protocol exists. Tailored approaches based on clinical and functional needs yield optimal outcomes, and further research is needed to identify the best practices.

Trends in treatment and epidemiology of radial head fractures

Objective

We aimed to assess the recent trends in the demographics of radial head and neck fractures and their management based on displacement.

Methods

TriNetX was queried for cases from 1 January 2017, through 31 December 2022. ICD diagnosis codes were used to define patient cohorts with radial head or neck fractures. CPT codes were searched to determine the operative patient cohorts. All cases not included under any CPT codes were defined as the nonoperative cohort.

Results

A total of 103,432 patients were included. The female-to-male ratio was 4:3. The average age of individuals with radial head fractures was 43 ± 25 years, with a greater age in the replacement cohort compared to the fixation group. The incidence rates of displaced and nondisplaced fractures were similar across the years. Nonoperative management was overwhelmingly preferred over operative management. Regarding operative management, internal fixation rates were higher than replacement rates.

Conclusion

The trend of fracture incidence and the type of operative management has remained constant over the past 6 years. However, an increase in the number of radial head replacements is expected with an aging population. Moreover, radial head and neck fractures are among the benign injuries most frequently managed nonoperatively.

Injectable double-crosslinked bone cement with enhanced bone adhesion and improved osteoporotic pathophysiological microenvironment for osteoregeneration in osteoporosis

The osteoporotic bone defect caused by excessive activity of osteoclasts has posed a challenge for public healthcare. However, most existing bioinert bone cement fails to effectively regulate the pathological bone microenvironment and reconstruct bone homeostasis in the presence of osteoclast overactivity and osteoblast suppression. Herein, inspired by natural bone tissue, an in-situ modulation system for osteoporotic bone regeneration is developed by fabricating an injectable double-crosslinked PEGylated poly(glycerol sebacate) (PEGS)/calcium phosphate cement (CPC) loaded with sodium alendronate (ALN) (PEGS/CPC@ALN) adhesive bone cement. By incorporating ALN, the organic-inorganic interconnection within PEGS/CPC@ALN results in a 100 % increase in compression modulus and energy dissipation efficiency. Additionally, PEGS/CPC@ALN effectively adheres to the bone by bonding with amine and calcium ions present on the bone surface. Moreover, this in-situ regulation system comprehensively mitigates excessive bone resorption through the buffering effect of CPC to improve the acidic microenvironment of osteoporotic bone and the release of ALN to inhibit hyperactive osteoclasts, and facilitates stem cell proliferation and differentiation into osteoblasts through calcium ion release. Overall, the PEGS/CPC@ALN effectively regulates the pathological microenvironment of osteoporosis while promoting bone regeneration through synergistic effects of drugs and materials, thereby improving bone homeostasis and enabling minimally invasive treatment for osteoporotic defects.

Osteoporosis Management for Shoulder Surgeons

PURPOSE OF REVIEW

The aim of this review is to aggregate currently available literature as it pertains to treating surgical shoulder pathology in patients with osteoporosis.

RECENT FINDINGS

Emerging data surrounding perioperative use of anti-osteoporosis medications for patients undergoing shoulder surgery have not shown definitively favorable or unfavorable outcomes. Similar evaluations in animal studies have shown promising results as a biologic augment to tendon and bone healing, especially with newer, anabolic agents. The mainstay of bone health management remains pre-operative evaluation, using opportunistic radiographic and CT based validated measurements, along with optimization of risk factors. Surgical techniques continue to incorporate implants that perform well in osteopenic bone. Promising pre-clinical studies have identified anabolic anti-osteoporosis medications as viable biologic augments to shoulder surgery, which has not been borne out in any clinical studies at this time.

Optimizing Treatment Strategies for Distal Radius Fractures in Osteoporosis: A Comparative Review

Osteoporosis is a common yet underdiagnosed condition that increases the risk of fractures, contributing to substantial morbidity, mortality, and healthcare costs. Distal radius fractures (DRFs) are some of the most common fractures associated with osteoporosis and often precede more severe fractures. Managing DRFs in patients with osteoporosis can be a challenge due to altered bone quality, which can affect healing and surgical fixation. This review examines both operative and nonoperative management strategies for DRFs in osteoporotic patients, emphasizing the importance of individualized treatment. Surgical interventions, like open reduction and internal fixation (ORIF) with plating, can facilitate early mobilization and improved alignment, especially in more active patients. However, osteoporosis poses risks such as hardware failure, infection, and malunion, calling for careful patient selection. Conversely, nonoperative management may be more suitable for patients with lower functional demands or higher surgical risks, despite the increased risk of malunion. By adapting treatment strategies to individual patient characteristics, orthopedic surgeons can optimize outcomes, minimize complications, and potentially prevent future fractures. Both operative and nonoperative treatments can yield positive outcomes when personalized to the patient's needs.

Bicortical Compression and Construct Stability With Variable Pitch Locking Screws in Cadaveric Specimens

OBJECTIVES

A variable pitch locking screw is intended to provide interfragmentary compression combined with fixed angle stability of locking plate constructs. The objective of this study was to compare variable pitch locking screws (3.5-mm KreuLock Ti locking compression screws, Arthrex Inc., Naples, FL) with standard locking screws (from the same manufacturer) in bicortical fixation scenarios in cadaver bone by assessing (1) interfragmentary compression and plate-bone compression and (2) construct biomechanical stability.

METHODS

Nine matched pairs of fresh-frozen cadaveric specimens with an average age of 67.2 years (range, 37-83) were used. Interfragmentary compression and plate-bone compression associated with insertion of single bicortical screws were compared between the variable pitch and standard locking screws at increasing levels of torque. The specimens tested were distal tibiae having a simulated longitudinal fracture. Additionally, fibulae were osteotomized to create a stable longitudinal fracture pattern and were fixed with a 5-screw plate construct with either all variable pitch or all standard locking screws. One of the 5 screws was placed across the osteotomy without lagging. Fibulae were tested cyclically with axial with torsional loading to compare displacements, rotation, and loads at failure or tested in 4-point bending to compare construct stiffness and maximum force to failure.

RESULTS

Interfragmentary and plate-bone compression forces in the distal tibia model varied across specimens but were significantly higher with variable pitch locking screws compared with standard locking screws [512 N (SD = 324 N) vs. 79 N (SD = 64 N), P = 0.002, and 242 N (SD = 119 N) vs. 104 N (SD = 123 N), P = 0.028, respectively]. In cyclic loading of fibula constructs, no significant differences were detected in construct axial displacement or angular displacement (P > 0.05). In 4-point bending, no differences were detected in maximum force or bending stiffness (P > 0.05).

CONCLUSIONS

Variable pitch locking screws produced interfragmentary compression between cortices and plate-bone compression that was greater than that produced by standard locking screws. In a stable bicortical fibula fixation scenario under external loading, the stability of variable pitch locking screw constructs was similar to constructs with standard locking screws.

An Outline on the Advancements in Surgical Management of Osteoporosis-Associated Fractures

Osteoporosis significantly impairs bone density and increases fracture risk, representing a substantial global health challenge. The effectiveness of traditional treatments such as calcium supplementation and exercise in completely preventing fractures is limited. This review explores recent advancements in surgical techniques and treatment modalities to manage osteoporotic fractures better and improve patient outcomes. Osteoporotic fractures demand specialized surgical techniques due to compromised bone quality. Vertebroplasty and kyphoplasty are minimally invasive procedures that provide rapid pain relief and structural support using bone cement. While vertebroplasty is effective, it carries risks of cement leakage and new fractures. Kyphoplasty, with added balloon inflation, reduces leakage risk and improves vertebral height restoration but is costlier. Cement-augmented screws enhance fixation but can increase adjacent fracture risk and pose long-term complications. Surgical advancements encompass robotic-assisted surgery, offering precision and accelerated recovery, alongside biologic agents like bone morphogenetic proteins (BMPs), which enhance bone healing while reducing secondary interventions and eliminating donor site morbidity. Bone graft substitutes such as calcium phosphate cements enhance biomechanical compatibility, decrease morbidity, and reduce fracture loss and pain. Balloon kyphoplasty aids in height restoration and pain relief and diminishes the risk of subsequent vertebral fractures. Bioglass scaffolds promote bone regeneration by improving bone mineral density and lowering the incidence of new fractures. Optimal perioperative care, including patient selection, nutritional management, and early mobilization strategies, is crucial for mitigating risks in vulnerable populations. While current surgical interventions provide significant pain relief and functional benefits, ongoing research and multidisciplinary collaboration are crucial to prospectively refine these techniques and reduce the burden of osteoporosis. New technologies, such as tissue engineering and gene editing, hold potential for future treatment paradigms.

The application of a dual-lead locking screw could enhance the reduction and fixation stability of the proximal humerus fractures: a biomechanical evaluation

Introduction

Bicortical screw fixation, which penetrates and fixes the near and far cortex of bone, has been conventionally used to achieve compressive fixation for fracture using screws. Open reduction and internal fixation using the locking plate are widely used for treating proximal humerus fractures. However, minimal contact between the bone and the locking plate can lead to an insufficient reduction. Theoretically, a dual-lead locking screw with different leads for the screw head and body could enhance the reduction and fixation stability of fragments in proximal humeral fractures without bicortical fixation, and achieve additional compression at the bone-plate-screw interface. This study assessed the insertion mechanics of the lead ratio of the dual-lead locking screw and its effect on the fixation stability of the proximal humerus fracture.

Methods

A Multi-Fix® locking plating system composed of ∅ 3.5 mm locking screws and a locking plate was used to make a locked plating for Sawbone bone blocks and fourth-generation composite humeri. Two different types of Sawbone bone blocks were used to simulate the osteoporotic (10 PCF) and normal cancellous (20 PCF) bones. The lead of the screw head thread (L head ) was 0.8 mm, and that of the screw body (L body ) was 0.8, 1.25, 1.6, 2.0, and 2.4 mm, whose lead ratios (R lead = L body / L head ) were 1.0, 1.56, 2.0, 2.5, and 3.0, respectively.

Results

The dual-lead locking screw elevated the compression between the locking plate and the bone. The elevation in the compression due to the dual-lead thread became weaker for the cancellous bone when the lead of the screw body was more than twice that of the screw head. The plate/humerus compression with strong bone quality withstood higher dual-lead-driven compression.

Discussion

A dual-lead locking screw of L body = 1.25 mm (R lead = 1.56 ) is recommended for maximum rotational stability for the locked humerus plating. The screws with over L body = 1.6 mm (R lead = 2 ) have no advantage in terms of the failure torque and maximum torsional deformation. Any locking dual-lead screw with a body thread lead of <1.6 mm (R lead = 2 ) can be used without the risk of bone crush when surgeons require additional compression to the locked cancellous bone plating.

Osteoporosis and Vertebral Column

Background

Osteoporosis is an age-related metabolic disease which has a significant impact on bone health and overall quality of life. It is gaining importance as a major medical consideration with the rapid increase in geriatric population globally. It increases the risk of vertebral fractures, progressive spinal deformities and neurological complications, contributing significantly to morbidity and mortality. Increase in life expectancy and advancement of medical technology has led to an increase in the proportion of geriatric patients undergoing orthopaedic procedures. It is becoming vital to adequately evaluate, investigate and treat osteoporosis before planning spinal surgery, especially spinal fusions and instrumentation.

Content

Historically, osteoporosis was considered a contraindication to spine surgery adding to the burden of Disability Adjusted Life Years (DALYs) and mortality. Conversely, osteoporotic patients who underwent spine surgery were not adequately optimized, leading to an increase in failure and complication rates. Better understanding of the pathophysiology of osteoporosis and the biomechanics of an osteoporotic spine with knowledge of current standards of treatment of osteoporosis facilitate the timely and adequate management of this disease. Advances in surgical and anaesthetic techniques facilitate successful surgeries on high-risk elderly and osteoporotic patients with multiple comorbidities allowing for a significantly high predictability for long-term positive outcomes.This article discusses the biomechanics of the osteoporotic spine, the diagnosis and management of osteoporotic patients with spinal disease, and the new treatments, recommendations, surgical indications, strategies and advances in instrumentation in patients with osteoporosis who require spinal surgery.

Implications

In this article, the authors aim to provide a generalized overview for better understanding of the pathophysiological processes underlying osteoporosis in the vertebral column. This review provides a comprehensive set of guidelines for overall health and management of spine patients with pathologies, either caused by or compounded with osteoporosis. An overview of current techniques, strategies and technologies designed to address the challenges associated with spine surgery in osteoporotic patients is also outlined.

Sources

Content for this article has been sourced from routinely cited articles available via PubMed, from National Institute of Health consensus development conference, from the recommendations by World Health Organization technical report series, from previous articles by the authors and from the protocols established by the authors in their clinical practice based on experience and detailed case reviews.

Spinolaminar locking plates improve fixation strength compared to pedicle screws: a biomechanical analysis

INTRODUCTION

Pedicle screw loosening is a significant complication of posterior spinal fixation, particularly among osteoporotic patients and in deformity constructs. In orthopedic trauma surgery, locking plates and screws have revolutionized the fixation of osteoporotic fractures. We have combined the traumatology principle of fixed-angle locking plate fixation with the spine principles of segmental instrumentation.

METHODS

A novel spinolaminar locking plate was designed based on morphometric studies of human thoracolumbar vertebrae. The plates were fixed to cadaveric human lumbar spines and connected to form 1-level L1-L2 or L4-L5 constructs and compared to similar pedicle screw constructs. Pure moment testing was performed to assess range of motion before and after 30,000 cycles of cyclic fatigue. Post-fatigue fixture pullout strength was assessed by applying a continuous axial tensile force oriented to the principal axis of the pedicle until pullout was observed.

RESULTS

Spinolaminar plate fixation resulted in superior pullout strength compared to pedicle screws (1,065 ± 400N vs. 714 ± 284N, p = 0.028). Spinolaminar plates performed equivalently to pedicle screws in range of motion reduction during flexion/extension and axial rotation. Pedicle screws outperformed the spinolaminar plates in lateral bending. Finally, no spinolaminar constructs failed during cyclic fatigue testing, whereas one pedicle screw construct did.

CONCLUSIONS

The spinolaminar locking plate maintained adequate fixation post-fatigue, particularly in flexion/extension and axial rotation compared to pedicle screws. Moreover, spinolaminar plates were superior to pedicle screw fixation with respect to cyclic fatiguing and pullout strength. The spinolaminar plates offer a viable option for posterior lumbar instrumentation in the adult spine.

3D Biomimetic Calcified Cartilaginous Callus that Induces Type H Vessels Formation and Osteoclastogenesis

The formation of a calcified cartilaginous callus (CACC) is crucial during bone repair. CACC can stimulate the invasion of type H vessels into the callus to couple angiogenesis and osteogenesis, induce osteoclastogenesis to resorb the calcified matrix, and promote osteoclast secretion of factors to enhance osteogenesis, ultimately achieving the replacement of cartilage with bone. In this study, a porous polycaprolactone/hydroxyapatite-iminodiacetic acid-deferoxamine (PCL/HA-SF-DFO) 3D biomimetic CACC is developed using 3D printing. The porous structure can mimic the pores formed by the matrix metalloproteinase degradation of the cartilaginous matrix, HA-containing PCL can mimic the calcified cartilaginous matrix, and SF anchors DFO onto HA for the slow release of DFO. The in vitro results show that the scaffold significantly enhances angiogenesis, promotes osteoclastogenesis and resorption by osteoclasts, and enhances the osteogenic differentiation of bone marrow stromal stem cells by promoting collagen triple helix repeat-containing 1 expression by osteoclasts. The in vivo results show that the scaffold significantly promotes type H vessels formation and the expression of coupling factors to promote osteogenesis, ultimately enhancing the regeneration of large-segment bone defects in rats and preventing dislodging of the internal fixation screw. In conclusion, the scaffold inspired by biological bone repair processes effectively promotes bone regeneration.

Improve biomechanical stability using intramedullary nails with femoral neck protection in femoral shaft fractures

BACKGROUND AND OBJECTIVE

Elderly patients treated for femoral shaft fractures have a higher risk of hip fracture. We hypothesized that intramedullary nails protecting the femoral neck can improve mechanical strength and reduce the risk of subsequent hip fracture. This study aims to analyze the biomechanical stability using intramedullary nails with or without femoral neck protection through finite element analysis.

METHODS

Thirty finite element models (FEMs) were established, including five different conditions of femoral shaft fracture: Fracture healing, Proximal fractures (Transverse and oblique), Distal fractures (Transverse and oblique), and five different fixation methods. Femoral neck protection groups: cephalomedullary nail (CN), reconstruction nail (RN); No femoral neck protection groups: type-1 of antegrade intramedullary nail (AIN-1), type-2 of antegrade intramedullary nail (AIN-2), and retrograde intramedullary nail (RIN). The maximum stress of bone and internal fixation in the femoral neck region for all type of fixation were calculated to evaluate the biomechanical stability.

RESULTS

Maximum equivalent stress values of bone in the femoral neck region for five different conditions of femoral shaft fracture: AIN-2 (77.23 MPa) >RIN (77.15 MPa) > AIN-1 (76.71 MPa) > CN (60.74 MPa) > RN (57.66 MPa) for the fracture healing; RIN (80.05 MPa) > AIN-1 (79.15 MPa) > AIN-2(78.77 MPa) > RN (65.16 MPa) > CN (65.03 MPa) for the proximal transverse fracture; RIN (80.10 MPa) > AIN-2 (79.36 MPa) > AIN-1 (79.18 MPa) > RN (65.09 MPa) > CN (64.96 MPa) for the proximal oblique fracture; RIN (80.24 MPa) > AIN-2 (79.68 MPa) > AIN-1 (79.33 MPa) > CN (65.02 MPa) > RN (64.76 MPa) for the distal transverse fracture; RIN (80.23 MPa) > AIN-2 (79.61 MPa) > AIN-1 (79.35 MPa) > CN (65.06 MPa) > RN (64.76 MPa) for the distal oblique fracture. Maximum equivalent stress of internal fixation in the femoral neck region is greater than the maximum stress of bone and avoids stress concentration of bone for the femoral neck protection groups (CN and RN).

CONCLUSIONS

Intramedullary nails with femoral neck protection in the treatment of femoral shaft fractures improve mechanical strength and prevent secondary hip fractures and decrease the overall risk of reoperation postoperatively.

Age and Spinal Disease Correlate to Albumin and Vitamin D Status

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

Thus, this study aimed to assess the epidemiological profile of a patient sample that underwent spinal surgery regarding their nutritional and vitamin D status.

METHODS

Serum albumin and vitamin D (25-hydroxyvitamin D) levels were measured in patients with different spinal surgical approaches and various pathologies at a single institution. 112 patients were retrospectively identified for inclusion and stratified by age into 4 age groups and by pathology. The nutritional status of the patients was classified in vitamin D inadequacy (< 30ng/mL), vitamin D deficiency (<20ng/mL), and hypoalbuminemia (<3.5g/dL). Data was analyzed comparing vitamin D, and albumin means considering gender, age group, and pathologies.

RESULTS

Twenty-eight (25.2%) patients had hypoalbuminemia. There was no difference between gender (p = 0.988); there was a significant decrease in albumin concentration increasing the age (p < 0.001). The prevalence of hypoalbuminemia was significantly higher in patients with trauma, tumor and infection than in those patients with degenerative and deformity diseases (p = 0.003). The prevalence of vitamin D inadequacy was 33.7%, and that of deficiency was 62.2%, while severe deficiency (< 10 ng/mL) in 16.3%. The vitamin D concentration was significantly different among the pathologies (P = 0.047), the lower concentration occurring in patients with tumor.

CONCLUSION

Older patients, as well as patients with tumor and infectious pathologies, seem to have a higher prevalence of hypoalbuminemia, inferring malnutrition. There was a low epidemic level of vitamin D concentration, almost all patients presenting some degree of hypovitaminosis D, independent of age, gender and nutritional status.

[Clavicle stress fracture following reverse shoulder arthroplasty]

Wir stellen den seltenen Fall einer Insuffizienzfraktur der Klavikula nach Implantation einer inversen Schulterendoprothese (RSA) vor. Als Ursache solcher Frakturen wird eine vermehrte Zugbelastung durch den Musculus deltoideus nach RSA diskutiert. In den wenigen verfügbaren Fallberichten zeigten die betroffenen Patienten deutliche Funktionseinschränkungen. Die Versorgung erfolgte im vorliegenden Fall mit Plattenosteosynthese. Trotz intraoperativ gutem Korrekturergebnis kam es im Verlauf ohne Trauma zum Osteosyntheseversagen mit weiterer Dislokation der Fraktur.

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.

Immersion in Raloxifene does not significantly improve bone toughness or screw pull-out strength in multiple in vitro models

BACKGROUND

Failure of surgical fixation in orthopaedic fractures occurs at a significantly higher rate in osteoporotic patients due to weakened osteoporotic bone. A therapy to acutely improve the mechanical properties of bone during fracture repair would have profound clinical impact. A previous study has demonstrated an increase in mechanical properties of acellular cortical canine bone after immersion in raloxifene. The goal of this study was to determine if similar treatment yields the same results in cancellous fetal bovine bone and whether this translates into a difference in screw pull-out strength in human cadaveric tissue.

METHODS

Cancellous bone from fetal bovine distal femora underwent quasi-static four-point bending tests after being immersed in either raloxifene (20 μM) or phosphate-buffered saline as a control for 7 days (n = 10). Separately, 5 matched pairs of human osteoporotic cadaveric humeral heads underwent the same procedure. Five 3.5 mm unicortical cancellous screws were then inserted at standard surgical fixation locations to a depth of 30 mm and quasi-static screw pull-out tests were performed.

RESULTS

In the four-point bending tests, there were no significant differences between the raloxifene and control groups for any of the mechanical properties - including stiffness (p = 0.333) and toughness (p = 0.546). In the screw pull-out tests, the raloxifene soaked samples and control samples had pullout strengths of 122 ± 74.3 N and 89.5 ± 63.8 N, respectively.

CONCLUSIONS

Results from this study indicate that cancellous fetal bovine samples did not demonstrate an increase in toughness with raloxifene treatment, which is in contrast to previously published data that studied canine cortical bone. In vivo experiments are likely required to determine whether raloxifene will improve implant fixation.

Anatomical quadrilateral plate for acetabulum fractures involving quadrilateral surface: A review

INTRODUCTION

The management of acetabulum fractures in osteoporotic elderly, as well as comminuted fractures in younger patients is likely to be difficult. These fractures need specific fixation techniques especially when the quadrilateral plate is involved. Standard implants may not be able to adequately support the fixation, so newer pre-shaped fixation plates have been proposed with some of these already in use. The concept of anatomic plates has come up for many fracture locations for providing a better buttress effect to the comminuted fragments. There has been a need to look for an anatomic buttress plates being developed for acetabulum fractures involving the quadrilateral surface.

MATERIALS AND METHODS

The literature has been reviewed to find the various newer designs that have been used for buttressing the quadrilateral surface in comminuted acetabular fractures. An attempt has been made to study their design characteristics and clinical outcomes. The review also includes the analysis of Anatomic Quadrilateral plate (AQP) used in fixation of acetabulum fracture involving quadrilateral surface in a series of 33 patients.

RESULTS

There has been few anatomical plates developed for the stabilization of acetabular quadrilateral surface fractures. Some of these plates have been successfully used in management of acetabular fractures primarily in young patients. Issues however remain in their application and outcomes in osteoporotic fractures of the acetabulum, as these plates support the pelvic brim fragments either from superior or medial surface. The newer development i.e. 'Anatomical Quadrilateral Plate' is optimized to counter the displacement forces due to its positioning on the pelvic brim rather than its superior or medial surface. Other special features include the possibility of longer screws across bone due to oblique position of holes, the typical location of a locking hole on the plate beam which permits dual cortical compression fixation either by using a bigger screw or a specially designed screw in screw construct across the supra-acetabular corridor. The option of using hybrid fixation of both locking and unlocked screws in AQP allows proper stress distribution on the underlying bone, aiding both primary as well as secondary stability. The minimum of one year post surgery outcome of patients having acetabular fixation using this Anatomic quadrilateral plate has been analyzed in 33 patients. Twenty three of these were aged more than 50 years and 28 out of total 33 were males. Associated injuries included Ipsilateral lower limb injury in 2 patients and distal radius fracture in 5 patients. The fracture pattern included 'Anterior column posterior hemi-transverse' in 10 patients,' Associated Both Column' injury in 9 and 'T type' acetabular fractures in 8 patients. Isolated 'Anterior column' was fractured in 6 patients. The surgical approach was 'Anterior Intra-pelvic' (AIP) in 23 patients and 'Modified Ileo-femoral' in other 10 patients. One patient had additional K L approach. Among the implants, the AQP plate was used without its pubic arm in 6 patients. The post-operative x rays showed anatomical reduction in 28 patients, while other 5 had gaps and/or steps up to 2 mm size. In subsequent car, one of these patients needed hip arthroplasty for problem arising due to collapse in fixation within six months. EQ 5D 5L telephonic score was used to know the outcome at minimum of one year follow up in 33 patients. As per this score, only 3 patients had an issue with mobility, with only one having problem in self-care activity. Six patients complained of minor limitations in carrying out their usual activities and only one patient had anxiety affecting him. In their self-assessment of overall health status, 22 patients marked it 100, 7 made it 90, 3 as 80 and 1 had marked it as 70 in a score range of 0-100. Considering the predominant elderly profile in this series of patients, the acetabular reconstruction using 'Anatomic quadrilateral plate' has shown encouraging results.

CONCLUSION

For stabilization of acetabular fractures involving quadrilateral surface area and pelvic brim, various new implants have been used. The Anatomic quadrilateral plate due to its anatomical shape, the various options in fracture fixation is best optimized for management of comminuted acetabulum fractures especially in poor quality bones. It has been successful in achieving good outcome in elderly group of patients having these complex injuries.

The effect of two types of resorbable augmentation materials - a cement and an adhesive - on the screw pullout pullout resistance in human trabecular bone

Augmentation materials, such as ceramic and polymeric bone cements, have been frequently used to improve the physical engagement of screws inserted into bone. While ceramic, degradable cements may ultimately improve fixation stability, reports regarding their effect on early fixation stability have been inconsistent. On the other hand, a newly developed degradable ceramic adhesive that can bond with tissues surrounding the screw, may improve the pullout performance, ensure early stability, and subsequent bony integration. The aim of this study was to investigate failure mechanisms of screw/trabecular bone constructs by comparing non-augmented screws with screws augmented with a calcium phosphate cement or an adhesive, i.e. a phosphoserine-modified calcium phosphate. Pullout tests were performed on screws inserted into trabecular cylinders extracted from human femoral bone. Continuous and stepwise pullout loading was applied with and without real-time imaging in a synchrotron radiation micro-computed tomograph, respectively. Statistical analysis that took the bone morphology into account confirmed that augmentation with the adhesive supported significantly higher pullout loads compared to cement-augmented, or non-augmented screws. However, the adhesive also allowed for a higher injection volume compared to the cement. In-situ imaging showed cracks in the vicinity of the screw threads in all groups, and detachment of the augmentation materials from the trabecular bone in the augmented specimens. Additional cracks at the periphery of the augmentation and the bone-material interfaces were only observed in the adhesive-augmented specimen, indicating a contribution of surface bonding to the pullout resistance. An adhesive that has potential for bonding with tissues, displayed superior pullout resistance, compared to a brushite cement, and may be a promising material for cementation or augmentation of implants.

Enhancement of local bone formation on titanium implants in osteoporotic rats by biomimetic multilayered structures containing parathyroid hormone (PTH)-related protein

Osteoporosis is a severe health problem causing bone fragility and consequent fracture. Titanium (Ti) implants, used in patients with osteoporotic fractures, are prone to failure because of the decreased bone mass and strength. Therefore, it is of utmost importance to fabricate implants possessing osteogenic properties to improve implant osseointegration. To improve the long-term survival rate of Ti implants in osteoporotic patients, hyaluronic acid/ϵ-polylysine multilayers containing the parathyroid hormone (PTH)-related protein (PTHrP) were deposited on Ti implants by a layer-by-layer (LBL) electro assembly technique. The murine pre-osteoblast cell line MC3T3-E1, possessing a high potential of osteoblast differentiation, was used to evaluate the osteo-inductive effects of Ti-LBL-PTHrP in vitro. In addition, the performance of the Ti (Ti-LBL-PTHrP) implant was evaluated in vivo in a femoral intramedullary implantation in Sprague Dawley rats. The Ti-LBL-PTHrP implant regulated the release of the loaded PTHrP to increase bone formation in the early stage of implantation. The in vitro results revealed that cells on Ti-LBL-PTHrP did not show any evident proliferation, but a high level of alkaline phosphatase activity and osteoblast-related protein expression was found, compared to the uncoated Ti group (p < 0.05). In addition, in vivo micro-CT and histological analysis demonstrated that the Ti-LBL-PTHrP implants could significantly promote the formation and remodeling of new bone in osteoporotic rats at 14 d after implantation. Overall, this study established a profound and straightforward methodology for the manufacture of biofunctional Ti implants for the treatment of osteoporosis.

Construction of multilayered molecular reservoirs on a titanium alloy implant for combinational drug delivery to promote osseointegration in osteoporotic conditions

In this study, β-cyclodextrin (β-CD) molecules are used as molecular reservoirs and grafted onto chitosan molecules for calcitriol (VD3) loading, which is a hormonally active metabolite of vitamin D. The resultant molecular complex is co-assembled with an antiosteoporosis drug calcitonin (CT) to form bio-functional multilayer structure on Ti6Al7Nb substrate via layer-by-layer self-assembly, which is capable of releasing VD3 and calcitonin in a sustained manner to modulate osteoblasts, osteoclasts, and macrophages at the bone-implant interface. In vitro results show that the released VD3 and CT individually upregulated the expression of calcium-binding protein (including Calbindin D9k and Calbindin D28k) and BMP2 in osteoblasts in peri-implant regions to stimulate their Ca deposition and differentiation. RAW264.7 cells (a murine macrophage) on the biofunctional implant displayed improved M2 phenotypical differentiation and expression of BMP2 and VEGF genes, but M1 phenotypical differentiation potential and MCF and TRAP gene expression levels are evidently lower. Results from in vivo micro-CT and histological analysis also demonstrate that VD3/CT co-loaded implant can dramatically enhance the bone remodeling under osteoporotic conditions with significantly enhanced interfacial shear strength and improved osseointegration as compared to other groups. The insights in this study offer new avenues for the rational functionalization of titanium implants to effectively repair osteoporotic fractures. STATEMENT OF SIGNIFICANCE: A promising strategy to enhance the recovery rate of osteoporotic fractures is to immobilize antiosteoporotic drugs onto the surface of titanium-based implants. In this study, we grafted beta-cyclodextrin (β-CD) onto chitosan (Chi) molecules to load VD3, which was co-assembled with calcitonin (CT) onto Ti6Al7Nb implants by the layer-by-layer assembly technique. The obtained functional titanium alloy implant (Ti6Al7Nb/LBL/Chi-CD@VD3/ CT) could stably release VD3 and calcitonin agents in a sustained manner. RAW264.7 cells grown on Ti6Al7Nb/LBL/Chi-CD@VD3/CT showed superior M2 phenotypical differentiation efficiency, but lower MCF/TRAP gene expression levels. In vitro and in vivo results showed that the released VD3 and CT individually upregulated the expression of calcium binding proteins and BMP2 in osteoblasts, promoting new bone formation in the peri-implant region.

Kirschner wire prepared pilot holes improve screw pullout strength in synthetic osteoporotic-type bone

OBJECTIVES

To compare the pullout strength and maximal insertional torque of pilot holes prepared with the traditional twist drill bit versus a smooth Kirschner wire.

METHODS

Pilot holes were prepared using a drill press with either a 2.5 mm twist drill bit or a 2.5 mm smooth Kirschner wire into 2 distinct polyurethane foam densities representing severe and mild osteoporotic bone. 3.5 mm cortical and 4.0 mm cancellous screws were then inserted freehand into the prepared holes. All permutations of pilot hole type, screw size and foam density were tested for maximum pullout strength and maximum insertional torque.

RESULTS

Kirschner wire prepared pilot holes resulted in significantly higher pullout load than drill bit holes in low density blocks (P < 0.001), but not in high density blocks (P = 0.232). There was no statistical difference (P > 0.05) for maximum insertional torque in the pilot hole preparation type.

CONCLUSION

In severely osteoporotic bone, Kirschner wire pilot hole preparation may improve screw pullout strength.

Bench-to-bedside strategies for osteoporotic fracture: From osteoimmunology to mechanosensation

Osteoporosis is characterized by a decrease in bone mass and strength, rendering people prone to osteoporotic fractures caused by low-energy forces. The primary treatment strategy for osteoporotic fractures is surgery; however, the compromised and comminuted bones in osteoporotic fracture sites are not conducive to optimum reduction and rigid fixation. In addition, these patients always exhibit accompanying aging-related disorders, including high inflammatory status, decreased mechanical loading and abnormal skeletal metabolism, which are disadvantages for fracture healing around sites that have undergone orthopedic procedures. Since the incidence of osteoporosis is expected to increase worldwide, orthopedic surgeons should pay more attention to comprehensive strategies for improving the poor prognosis of osteoporotic fractures. Herein, we highlight the molecular basis of osteoimmunology and bone mechanosensation in different healing phases of elderly osteoporotic fractures, guiding perioperative management to alleviate the unfavorable effects of insufficient mechanical loading, high inflammatory levels and pathogen infection. The well-informed pharmacologic and surgical intervention, including treatment with anti-inflammatory drugs and sufficient application of antibiotics, as well as bench-to-bedside strategies for bone augmentation and hardware selection, should be made according to a comprehensive understanding of bone biomechanical properties in addition to the remodeling status of osteoporotic bones, which is necessary for creating proper biological and mechanical environments for bone union and remodeling. Multidisciplinary collaboration will facilitate the improvement of overall osteoporotic care and reduction of secondary fracture incidence.

Experimental Evaluation of Screw Pullout Force and Adjacent Bone Damage According to Pedicle Screw Design Parameters in Normal and Osteoporotic Bones

This paper proposes an optimum design of the pedicle screw with respect to bone density and variables of the screw design. First, pedicle screws are designed and manufactured with design variables including the core diameter and conical angle that affect the pullout force of the pedicle screw. Variables of bone density are also classified into two groups, namely grade 10 (0.16 g/cc) with osteoporotic bone density and grade 20 (0.32 g/cc) with normal bone density. The effect of each parameter on the pullout force and relationship between the pullout force and screw designs are investigated. Furthermore, bone damage after fixation failure or insertion in the patient body is considered separately from the pullout strength. Therefore, cross sectional images of the artificial bone are observed to analyze the degree of damage after the pullout test of the pedicle screw by using micro-CT (computed tomography). The region and degree of bone damage are quantitatively analyzed. The effects of the core diameter and conical angle of the pedicle screw on the pulling force, bone damage, and fracture behavior are analyzed via the aforementioned experiments and analysis. An optimal pedicle screw design is suggested based on the experimental results.

Paradigm shift in geriatric fracture treatment

The number of geriatric patients is increasing. These patients exhibit specific characteristics, which influence the type of fracture care. Many patients have comorbidities, which make them more vulnerable to surgical procedures. The soft tissue envelope around the fracture often is compromised due to pre-existing diseases such as diabetes, chronic venous insufficiency or peripheral vascular disease. Bone mineral density has decreased, which enhances the risk of implant loosening. The goals of treatment differ from those, which are valid for younger adults. Primary goal is preserving independency of the elderly patient in his activities of daily life. Advantages and drawbacks of surgical procedures have to be balanced with those of conservative treatment. Fractures of the lower extremities will more often need surgical treatment than fractures of the upper extremities. Patient´s autonomy is best obtained by creating high stability in the fracture plane, which enables motion and weight-bearing. Second priority is prevention of general and local post-operative complications by the use of less invasive surgical procedures. Restoring anatomy and optimal function are less important goals. The implants, which are used, are inserted through small incisions, placed deep under the skin and use long anatomic or osseous corridors. Intramedullary devices have important advantages. This paradigm shift takes the special challenges and requirements of geriatric patients into account.

Biomechanical comparison between standard and inclined screw orientation in dynamic hip screw side-plate fixation: The lift-off phenomenon

Background

Common failure modes of dynamic hip screw are cut-out and lift-off. To minimize the latter, distal screws can be inserted in different orientations. However, the effectiveness remains controversial. The aim of this study was to biomechanically investigate the influence of distal screw orientation on construct stability.

Methods

Thirty artificial generic long bones were assigned to three groups (n = 10) and fixed with two-hole dynamic hip screw–plates, inserting distal cortical screws with neutral parallel screw orientation (A), divergent screw orientation (B) or convergent screw orientation (C). Starting at 60 N, cyclic loading was applied to the implant tip perpendicular to the lag screw axis with progressive peak load increase at a rate of 0.002 N/cycle until failure. Parameters of interest were construct stiffness and machine actuator displacement after 250, 1000 and 5000 cycles, as well as cycles to failure.

Results

Displacement after 250, 1000 and 5000 cycles was significantly higher in Group C than in Groups A and B, p < 0.01, whereas no significant differences were observed between Groups A and B, p = 0.20. Specimens in Group C failed after 11,584 [standard deviation (SD), 5924] cycles, significantly earlier than those in Groups A and B [A: 27,351 (SD, 12,509); B: 28,793 (SD, 14,764)], p ≤ 0.02. Cycles to failure were not significantly different between Groups A and B, p > 0.99.

The translational potential of this article

Parallel or divergent distal screw insertion provides similar construct stability in terms of resistance to plate lift-off. In contrast, converging screw insertion leads to inferior stability and is not advisable from a biomechanical point of view.

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.

Treatment of displaced transverse fractures of the patella: modified tension band wiring technique with or without augmented circumferential cerclage wire fixation

BACKGROUND

Displaced transverse fractures of the body of the patella are usually associated with disruption of extensor mechanism and should be fixed surgically. The most common method is a tension band wiring (TBW) technique. Some surgeons concurrently employ an augmented circumferential cerclage wiring (ACCW) technique to help fracture stabilization and aid in fracture healing; however, its role and effect on the treatment outcomes is unclear.

METHODS

We performed a STROBE-compliant retrospective observational cohort study on all cases of acute closed patella fracture that were treated at our institution between 2006 and 2012. Of 185 episodes, 72 (38.9%) were eligible for this study according to our inclusion/exclusion criteria. We classified these subjects with AO/OTA type 34-C1.1 or 34-C2 lesions into two groups for analyses: fractures treated with modified TBW and ACCW (group 1, n = 27) and those treated with modified TBW alone (group 2, n = 45). Plain radiographs were used to evaluate radiographic outcomes and the effect of potential risk factors on fixation failure was analyzed by subgroup comparisons.

RESULTS

Our results revealed that there were no significant differences in the rates of fixation failure (P = 0.620), nonunion (P = 0.620), and revision surgery (P = 0.620) between the groups. Although not statistically significant, there was a trend towards a positive risk association between fixation failure and age distribution > 60 years (10.0% vs. 0.0%, P = 0.124; OR = 8.0, P = 0.168) and > 70 years (9.4% vs. 2.5%, P = 0.321; OR = 4.0, P = 0.237) and the superficial level of the K-wires (12.0% vs. 1.5%, P = 0.117; OR = 6.3, P = 0.121). Regarding those modified TBW patients concurrently treated with an ACCW, the potential risk association between fixation failure and the superficial level of the K-wire was prone to increase further (28.6% vs. 0.0%, P = 0.060; OR = 18.6, P = 0.071).

CONCLUSIONS

Concurrent application of an ACCW might be needless and not efficacious to help fracture stabilization and healing in patients having been treated with modified TBW for displaced transverse fractures of the body of the patella. Adherence to correct surgical technique such as putting the K-wires at the proper level and securing control of the both ends of the K-wires may be more important and help in improving outcomes.

Internal Fixation of Osteoporotic Bone

Osteoporosis is one of the costliest conditions managed by orthopaedic surgeons. This condition, which is characterized by decreased bone density and thinning of cortical bone, is strongly influenced by complex signaling in both the hormonal and mechanical environments. Osteoporosis cannot be cured; instead, it can only be managed to decrease patient morbidity. Current pharmacologic treatments are aimed at minimizing bone turnover and have substantial side effects. Therefore, much work remains to find safer and more effective agents to restore bone density. In addition to the high incidence of fracture in elderly patients, many of the traditional fixation constructs used for repair of these fractures are not suitable for use in osteoporotic bone. Increased use of fixed-angle locking plates, intramedullary devices, and bone substitutes has greatly improved outcomes in these patients.

Development of controlled drug delivery systems for bone fracture-targeted therapeutic delivery: A review

Impaired fracture healing is a major clinical problem that can lead to patient disability, prolonged hospitalization, and significant financial burden. Although the majority of fractures heal using standard clinical practices, approximately 10% suffer from delayed unions or non-unions. A wide range of factors contribute to the risk for nonunions including internal factors, such as patient age, gender, and comorbidities, and external factors, such as the location and extent of injury. Current clinical approaches to treat nonunions include bone grafts and low-intensity pulsed ultrasound (LIPUS), which realizes clinical success only to select patients due to limitations including donor morbidities (grafts) and necessity of fracture reduction (LIPUS), respectively. To date, therapeutic approaches for bone regeneration rely heavily on protein-based growth factors such as INFUSE, an FDA-approved scaffold for delivery of bone morphogenetic protein 2 (BMP-2). Small molecule modulators and RNAi therapeutics are under development to circumvent challenges associated with traditional growth factors. While preclinical studies has shown promise, drug delivery has become a major hurdle stalling clinical translation. Therefore, this review overviews current therapies employed to stimulate fracture healing pre-clinically and clinically, including a focus on drug delivery systems for growth factors, parathyroid hormone (PTH), small molecules, and RNAi therapeutics, as well as recent advances and future promise of fracture-targeted drug delivery.

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.

Simple 3,4-Dihydroxy-L-Phenylalanine Surface Modification Enhances Titanium Implant Osseointegration in Ovariectomized Rats

Osteoporosis presents a challenge to the long-term success of osseointegration of endosseous implants. The bio-inspired 3,4-dihydroxy-L-phenylalanine (Dopa) coating is widely used as a basic layer to bind osteogenetic molecules that may improve osseointegration. To date, little attention has focused on application of Dopa alone or binding inhibitors of bone resorption in osteoporosis. Local use of a bisphosphonate such as zoledronic acid (ZA), an inhibitor of osteoclast-mediated bone resorption, has been proven to improve implant osseointegration. In this study, ovariectomized rats were divided into four groups and implanted with implants with different surface modifications: sandblasted and acid-etched (SLA), SLA modified with Dopa (SLA-Dopa), SLA modified with ZA (SLA-ZA), and SLA modified with Dopa and ZA (SLA-Dopa + ZA). Measurement of removal torque, micro-computed tomography and histology revealed a greater extent of bone formation around the three surface-modified implants than SLA-controls. No synergistic effect was observed for combined Dopa + ZA coating. Microarray analysis showed the Dopa coating inhibited expression of genes associated with osteoclast differentiation, similarly to the mechanism of action of ZA. Simple Dopa modification resulted in a similar improvement in osseointegration compared to ZA. Thus, our data suggest simple Dopa coating is promising strategy to promote osseointegration of implants in patients with osteoporosis.

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.

p21-/- mice exhibit enhanced bone regeneration after injury

Background

p21^{(WAF1/CIP1/SDI1)}, a cyclin dependent kinase inhibitor has been shown to influence cell proliferation, differentiation and apoptosis; but more recently, p21 has been implicated in tissue repair. Studies on p21(^−/−) knockout mice have demonstrated results that vary from complete regeneration and healing of tissue to attenuated healing. There have however been no studies that have evaluated the role of p21 inhibition in bone healing and remodeling.

Methods

The current study employs a burr-hole fracture model to investigate bone regeneration subsequent to an injury in a p21^−/− mouse model. p21^−/− and C57BL/6 mice were subjected to a burr-hole fracture on their proximal tibia, and their bony parameters were measured over 4 weeks via in vivo μCT scanning.

Results

p21^−/− mice present with enhanced healing from week 1 through week 4. Differences in bone formation and resorption potential between the two mouse models are assessed via quantitative and functional assays. While the μCT analysis indicates that p21^−/− mice have enhanced bone healing capabilities, it appears that the differences observed may not be due to the function of osteoblasts or osteoclasts. Furthermore, no differences were observed in the differentiation of progenitor cells (mesenchymal or monocytic) into osteoblasts or osteoclasts respectively.

Conclusions

Therefore, it remains unknown how p21 is regulating enhanced fracture repair and further studies are required to determine which cell type(s) are responsible for this regenerative phenotype.

Electronic supplementary material

The online version of this article (10.1186/s12891-017-1790-z) contains supplementary material, which is available to authorized users.

Influence of Hydroxyapatite Stick on Pedicle Screw Fixation in Degenerative Lumbar Spine: Biomechanical and Radiologic Study

STUDY DESIGN

A prospective, within-patient, left-right comparative study.

OBJECTIVE

To evaluate the efficacy of hydroxyapatite (HA) stick augmentation method by comparing the insertional torque of the pedicle screw in osteoporotic and nonosteoporotic patients.

SUMMARY OF BACKGROUND DATA

Unsatisfactory clinical outcomes after spine surgery in osteoporotic patients are related to pedicle screw loosening or pull-outs. HA, as a bone graft extender, has a possibility to enhance the fixation strength at the bone-screw interface.

METHODS

From November 2009 to December 2010, among patients who required bilateral pedicle screw fixation for lumbar spine surgery, 22 patients were enrolled, who recieved unilateral HA stick augmentation and completed intraoperative insertional torque measurement of each pedicle screws. On the basis of preoperative evaluation of bone mineral density, patients with osteoporosis had 2 HA sticks inserted unilaterally, and 1 stick for patients without osteoporosis. Pedicle screw loosening and pull-outs were assessed using 12-month postoperative CT scans and follow-up radiographs. Clinical evaluation was done preoperatively and at 1 year postoperatively, based on Visual Analog Scale score, Oswestry Disability Index, and Short Form-36 Health Survey.

RESULTS

Regardless of bone mineral density, the average torque value of all pedicle screws with HA stick insertion (HA stick inserted group) was significantly higher than that of all pedicle screws without HA insertion (control group) (P<0.0001). Same results were seen in the HA stick inserted subgroups and the control subgroups within both of the osteoporosis group (P=0.009) and the nonosteoporosis group (P=0.0004). There was no statistically significant difference of the rate of pedicle screw loosening in between the HA stick inserted group and the control group. Clinical evaluation also showed no statistically significant difference in between patients with loosening and those without.

CONCLUSIONS

The enhancement of initial pedicle screw fixation strength in osteoporotic patients can be achieved by HA stick augmentation.

Trabecular deformations during screw pull-out: a micro-CT study of lapine bone

The mechanical fixation of endosseous implants, such as screws, in trabecular bone is challenging because of the complex porous microstructure. Development of new screw designs to improve fracture fixation, especially in high-porosity osteoporotic bone, requires a profound understanding of how the structural system implant/trabeculae interacts when it is subjected to mechanical load. In this study, pull-out tests of screw implants were performed. Screws were first inserted into the trabecular bone of rabbit femurs and then pulled out from the bone inside a computational tomography scanner. The tests were interrupted at certain load steps to acquire 3D images. The images were then analysed with a digital volume correlation technique to estimate deformation and strain fields inside the bone during the tests. The results indicate that the highest shear strains are concentrated between the inner and outer thread diameter, whereas compressive strains are found at larger distances from the screw. Tensile strains were somewhat smaller. Strain concentrations and the location of trabecular failures provide experimental information that could be used in the development of new screw designs and/or to validate numerical simulations.

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.

Tension wiring to increase stability of conventional plating for proximal humeral fractures: An alternative to a locking plate

Fixation of comminuted or osteoporotic fractures in the proximal humerus is a challenge for orthopedic surgeons. In the past two decades, locking plates have been used for proximal humeral fracture fixation. However, complications such as loss of reduction have been reported, and the implants are not always available in some regions. Therefore, we describe an alternative procedure involving fixation with a nonlocking cloverleaf plate augmented with tension wiring to provide adequate stability and prevent loss of reduction.

Management principles of osteoporotic fractures

Osteoporotic fractures are difficult to manage. They pose a number of difficulties to the surgeon arising from the underlying poor bone stock compromising the intention to achieve optimum fixation. Moreover, the frail elderly patients present with a variety of medical co-morbidities increasing the risk of developing perioperative complications. Despite these recognized challenges, there are currently a number of improving technologies and strategies at the surgeon's disposal to provide more confidence with fracture fixation and maximize the chance of success.

The Biomechanical Properties of Pedicle Screw Fixation Combined With Trajectory Bone Cement Augmentation in Osteoporotic Vertebrae

STUDY DESIGN

The biomechanics of pedicle screw fixation combined with trajectory cement augmentation with various filling volumes were measured by pull-out, periodic antibending, and compression fatigue tests.

OBJECTIVE

To investigate the biomechanical properties of the pedicle screw fixation combined with trajectory bone cement (polymethylmethacrylate) augmentation in osteoporotic vertebrae and to explore the optimum filling volume of the bone cement.

SUMMARY OF BACKGROUND DATA

Pedicle screw fixation is considered to be the most effective posterior fixation method. The decrease of the bone mineral density apparently increases the fixation failure risk caused by screw loosening and displacement. Trajectory bone cement augmentation has been confirmed to be an effective method to increase the bone intensity and could markedly increase the stability of the fixation interface.

METHODS

Sixteen elderly cadaveric 1-5 lumbar vertebral specimens were diagnosed with osteoporosis. The left and right vertebral pedicles were alternatively randomized for treatment in all groups, with the contralateral pedicles as control. The study groups included: group A (pedicle screw fixation with full trajectory bone cement augmentation), group B (75% filling), group C (50% filling), and group D (25% filling). Finally, the bone cement leakage and dispersion were assessed and the mechanical testing was conducted.

RESULTS

The bone cement was well dispersed around the pedicle screw. The augmented bone intensity, pull-out strength, periodic loading times, and compression fatigue performance were markedly higher than those of the control groups. With the increase in trajectory bone cement, the leakage was also increased (P<0.05). The pull-out strength of the pedicle screw was increased with an increase in bone mineral density and trajectory bone cement. It peaked at 75% filling, with the largest power consumption.

CONCLUSIONS

The optimal filling volume of the bone cement was 75% of the trajectory volume (about 1.03 mL). The use of excessive bone cement did not increase the fixation intensity but increased the risk of leakage.

Fracture repair: general aspects and influence of osteoporosis and anti-osteoporosis treatment

Bone differs from other tissues in its capacity to self-repair after a fracture. The low bone mass and structural deterioration of bone associated with osteoporosis increases the risk of fragility fracture compared with healthy individuals. The intention of this article is to review the complex process of fracture repair and essential requirements for a successful fracture healing response summarized as the "diamond concept" in terms of aging and osteoporosis. The current preclinical and clinical evidence for a beneficial or harmful influence of anti-osteoporosis medications such as bisphosphonates, parathyroid hormone (PTH), strontium ranelate and antibodies of Wnt-inhibiting signaling proteins on bone healing is presented and discussed. Literature suggests that there are no detrimental consequences of such therapeutics on fracture repair processes. Following a fragility fracture, it seems that early start of preventive anti-osteoporotic treatment right after surgery does not delay the union of the fracture, except perhaps in the case of very rigidly fixed fracture requiring direct bone healing. There is some promising experimental and clinical evidence for possible enhancement of the bone repair process via administration of systemic agents. Further well designed studies in humans are necessary to accumulate more evidence on the positive effects and to translate this knowledge into valid therapeutic applications.

Reducing Fracture Risk Adjacent to a Plate With an Angulated Locked End Screw

OBJECTIVES

Locking screws often are used in the treatment of osteoporotic fractures. Studies show that locking screws can increase bone stresses at the plate end, which increases the possibility of peri-implant fracture. This study evaluates whether the technique used to insert the end screw is related to the fracture tolerance adjacent to the plate.

METHODS

Twelve groups of plate constructs were evaluated using a fibular diaphyseal surrogate with mechanical properties similar to osteoporotic bone. All inboard screws were nonlocked with only the end screw fixation differing among groups. The end screws were inserted either perpendicularly to the plate or at an angle of 30 degrees for 6- and 12-hole plates. For both orientations, the end screws were inserted nonlocked, locked, or by a locked overdrilling technique, resulting in 6 groups per plate length. The perpendicular nonlocked screws represented a control group. The constructs were tested to failure in 4-point bending to determine peak load, failure energy, and stiffness.

RESULTS

All constructs failed by peri-implant fracture along a plane through the 2 cortical holes of the end screw. Compared with the control group, an angulated locked screw at the plate end significantly increased the peak bending moment and energy required to produce a fracture for both plate lengths (6-hole, P = 0.008, P < 0.001; 12-hole, P = 0.006, P < 0.001).

CONCLUSIONS

The use of an angulated locked end screw may enhance the resistance of osteoporotic bone to peri-implant fractures caused by bending forces.

Paget Disease of Bone

The current understanding of Paget disease of bone (PDB) has vastly changed since Paget described the first case in 1877. Medical management of this condition remains the mainstay of treatment. Surgical intervention is usually only used in fractures through pagetic bone, need for realignment to correct deformity in major long bones, prophylactic treatment of impending fractures, joint arthroplasty in severe arthritis, or spinal decompression in cases of bony compression of neural elements. Advances in surgical technique have allowed early return to function and mobilization. Despite medical and surgical intervention, a small subset of patients with PDB develops Paget sarcoma.

How to Use Fluoroscopic Imaging to Prevent Intraarticular Screw Perforation During Locked Plating of Proximal Humerus Fractures: A Cadaveric Study

OBJECTIVE

Intraarticular screw perforation is a common complication of open reduction and internal fixation of proximal humerus fractures. The purpose of this study was to (1) determine the sensitivity and specificity of the fluoroscopic images used to evaluate whether a screw tip has perforated into the glenohumeral joint, and (2) determine the specific fluoroscopic views that best evaluate screw position in the humeral head.

METHODS

Twenty-two proximal humeri in 11 lightly embalmed cadavers were instrumented. The articular surface was divided into equal-sized rows (superior, central, inferior) and columns (anterior, middle, posterior). The screws in 10 humeri were inserted and so their tips were located 2 mm beneath the articular surface. Twelve humeri had screws placed such that their tips protruded 2 mm past the articular surface into the glenohumeral joint. Twenty-seven different C-arm views were obtained of each specimen/screw configuration.

RESULTS

There were zero false-positives (100% specificity). The average sensitivity was 55% and varied greatly depending on the image view and the screw exit location (range, 0%-100%). The sensitivity for the inferior row of screws was the lowest (39.1%) and was particularly low for the posterior-inferior screw exit location (20.7%).

CONCLUSIONS

Screws that are completely located within the bone of the proximal humerus will never appear on C-arm images as intraarticular. However, screws that are intraarticular may appear to be completely located within the bone of the proximal humerus on some C-arm images. A sensitivity of 100% for detecting intraarticular screws for 8 of the 9 screws' exit locations and 90% for the posterior-inferior screw can be achieved by imaging the proximal humerus in 25-degree internal rotation, neutral, and 25-degree external rotation with the C-arm in neutral cant at rainbow 25-degree roll over, neutral rainbow, and rainbow 25-degree roll back for a total of 9 images.

Effects of Ovariectomy and Corticosteroid-Induced Osteoporosis on the Osteoinductivity of rhBMP-2 in a Segmental Long-Bone Defect Model

This study used the segmental long-bone defect model to assess the effects of osteoporosis on the formation of new bones and the osteoinductivity of recombinant human bone morphogenetic protein-2 (rhBMP-2). Seventy-two female Sprague-Dawley rats were divided into two groups: an osteoporosis group with ovariectomies and dexamathasone intramuscular injections and a sham group. When they reached 22 weeks in age, each group was further divided into two groups and a 5-mm defect was made in both fibular mid-shafts of each rat. One fibula in each rat was picked randomly and was injected with 0.05 mL of hydrogel carrier; the opposite fibula was injected with the same carrier mixed with rhBMP-2 (10 μg). After rearing for a further 5 and 9 weeks, the ratios of the lengths of the newly formed bones in the fibular defects were determined using micro-CT and undecalcified histology. The sham rhBMP-2-injected group-in all of the 5- and 9-week-kept groups-showed a significantly higher bridging bone formation ratio than the other three groups. The osteoporosis rhBMP-2-injected group showed a significantly higher ratio than both the non-rhBMP-2-injected sham hydrogel and the osteoporosis hydrogel groups. The comparison of the micro-CT parameters of the newly formed bones showed that the sham rhBMP-2 group at both 5 and 9 weeks compared with the osteoporosis rhBMP-2 group had significantly higher percentage bone volumes, trabecular thicknesses, and trabecular numbers, in addition to significantly lower specific surfaces, trabecular pattern factors, and structural model indices. The histology results showed that the sham-rhBMP-2 group began forming bridging bones in the defect areas at 5 weeks, and at 9 weeks, trabeculae and marrow spaces were observed. However, the osteoporosis rhBMP-2 group exhibited a relatively minor level of new bone and trabecula formation. Consequently, the rhBMP-2 group showed significantly increased bone formation in the osteoporosis rat fibular defect model compared with the hydrogel group, whereas the new bone quantities, qualities, and remodeling in the osteoporosis rhBMP-2 group were less effective than those in the sham-rhBMP-2 group, signaling that ovariectomy and corticosteroid-induced osteoporosis significantly undermines rhBMP-2 osteoinductivity.

Sclerostin and skeletal health

Sclerostin is a cysteine-knot glycoprotein product of the SOST gene, predominately expressed by osteocytes, that is a regulator of osteoblastic bone formation. When sclerostin binds to its low-density lipoprotein receptor-related proteins 5 and 6 on the cell membrane of osteoblasts, it inhibits canonical Wnt/β-catenin signaling and reduces osteoblastic bone formation. Sclerostin was first identified in the study of two rare autosomal recessive disorders, sclerosteosis and van Buchem disease, which are associated with absent or reduced levels of sclerostin. Although homozygote patients with these disorders have serious adverse clinical consequences due to excessive bone growth, heterozygote patients have a normal phenotype, high bone mass, and very low risk of fractures. This has led to the concept that downregulation of sclerostin might be effective in the treatment of osteoporosis. Several humanized monoclonal antibodies to sclerostin, including romosozumab and blosozumab, are now in clinical development. Preliminary data show that these agents result in a transient increase in bone formation markers, a sustained decrease in bone resorption markers, and a robust increase in bone mineral density. If any of these agents are found to reduce fracture risk with a favorable safety profile, it will expand the options for osteoanabolic therapy for patients at high risk for fractures.

Acetabular fractures labelled poor surgical choices: Analysis of operative outcome

PURPOSE

We report the surgical outcome in 52 patients with acetabular otherwise considered as poor surgical choices.

METHODS

43 male and 9 female patients were operated at a mean age of 43 years and followed up for a mean duration of 60.3 months. There were 22 elementary fractures and 31 associated ones according to Letournal and Judet classification. Osteosynthesis was attempted in 48 patients whereas a primary total hip arthroplasty was performed in 4 patients. Outcome was assessed radiologically and functionally employing Harris Hip Score (HHS).

RESULTS

Average HHS in osteosynthesis group was 82.56 ± 12.4 with excellent to good results in 59.6% of the cases. Symptomatic osteoarthritis occurred in 13.5% of cases, avascular necrosis and severe heterotopic ossification in 7.7% each, infection and nerve palsy in 11.5% each.

CONCLUSION

Although the complication rates in this series is marginally more than that reported in literature, we recommend that the indications of surgical fixation in acetabular fractures need to be extended to those which were considered poor surgical choices.

Internal fixation of osteoporotic fractures

Osteoporosis leads to bone fragility and increased risk of fracture. Despite advances in diagnosis and treatment, the prevalence continues to rise. Osteoporotic fracture treatment has a unique set of difficulties related to poor bone quality and traditional approaches, and implants may not perform well. Fixation failure and repeat surgery are poorly tolerated and highly undesirable in this patient population. This review illustrates the most recent updates in internal fixation, implant design, and surgical theory regarding treatment of patients with osteoporotic fractures.