Bone fracture nonunion rate decreases with increasing age: A prospective inception cohort study

Chronic heavy alcohol consumption impairs the ability of demineralized allogenic bone matrix to support osteoinduction in alcohol-naïve rats

Allografts play an important role in treatment of complex bone fractures and deformities. The purpose of this study was to test the hypothesis that alcohol consumption impairs graft incorporation and bone healing by two mechanisms: (1) by lowering osteoinductive capacity and (2) by suppressing bone formation. We performed experiments using a demineralized allogeneic bone matrix (DBM) model in which DBM harvested from donor rats fed control or ethanol diet was implanted subcutaneously into recipient rats fed control or ethanol diet. We also evaluated the efficacy of intermittent parathyroid hormone (PTH) on bone graft incorporation (DBM from donor rats fed alcohol or control diet) using a critical size defect model. Bone formed during osteoinduction was measured by micro-computed tomography. Experiment 1: Bone volume was lower in DBM harvested from ethanol-consuming donors 6 weeks following implantation into recipients fed control diet, indicating that exposure of the donor rats to ethanol lowered osteoinductive capacity. Experiment 2: Bone volume was lower in DBM harvested 3 weeks following implantation from ethanol-consuming donors into ethanol-consuming recipients compared to DBM harvested from control donors implanted into control recipients or DBM harvested from control donors implanted into ethanol-consuming recipients. Experiment 3: Ethanol consumption by donors resulted in a tendency for lower DBM bone volume (p = 0.085) whereas PTH treatment resulted in higher DBM bone volume in the critical size defect model. Our results suggest that chronic heavy alcohol consumption by allograft donors may impair osteoinduction and this negative outcome may be worsened by alcohol intake during bone healing. Additionally, PTH has the potential to increase osteoinduction in DBM harvested from both abstinent and alcohol-consuming donors.

Vascular participation in bone healing: Implications related to advancing age and morbidity

Fracture non-union and the related morbidities represent a global health concern. While many factors are necessary for proper bone healing following fracture, the vascular system is requisite. Important considerations include vascular morphology in bone and marrow and the regulation of tissue blood flow. This review discusses the types of fracture management and associated bone repair (i.e., intramembranous vs. endochondral), the phases of bone healing, and the role of the bone vascular network. Finally, fracture healing is considered in the context of advanced age and morbidity.

Risk factors for non-union in foot and ankle arthrodesis: a population-based case-control study using registry data

BACKGROUND

Nonunion is a common complication following foot and ankle arthrodesis. This study endeavoured to determine the risk factors for nonunion in foot and ankle arthrodesis.

METHODS

This was a retrospective case-control study using the National Health Insurance Research Database. Patients who underwent foot and ankle arthrodesis with a minimum follow-up duration of 6 months were included. International Classification of Diseases codes were used to identify diagnoses and treatment. Patients with nonunion were matched by age and sex with patients with union at a ratio of 1:4. Logistic regression was performed to compare between patients with nonunion and controls with union to ascertain the effects of various risk factors.

RESULTS

A total of 107 joints were identified as nonunion, and 428 age- and sex-matched controls were selected. Patients with diabetes mellitus had a 1.710 times (95% CI = 1.060 - 2.756, p = 0.0278) higher risk of nonunion than those without. No significant differences were observed in the risk of nonunion in relation to which joint was treated; the presence of osteoarthritis, traumatic osteoarthritis, rheumatoid arthritis, osteoporosis, or open/arthroscopic arthrodesis; internal or external fixation; or the usage of a bone graft. For patients without diabetes mellitus, those who underwent arthrodesis in the tarsometatarsal joint had a 6.507 times (95% CI: 1.045 - 40.522, p = 0.0256) higher risk of nonunion compared to those who underwent arthrodesis in the ankle joint.

CONCLUSION

Diabetes mellitus increases the risk of nonunion among patients with and without diabetes mellitus. For those without diabetes mellitus, arthrodesis in the tarsometatarsal joint is associated with the highest risk of nonunion.

Nonunion Fractures: Trends in Epidemiology and Treatment of Femur Fractures, 2017-2022

BACKGROUND

The incidence of femur fractures has increased in recent years, along with the rate of surgery and subsequent nonunion following these fractures. Nonunion is a significant concern due to the burden it places on both patients and the healthcare system. This study aims to investigate the demographic factors associated with femoral shaft fracture nonunion by comparing two surgical management approaches: open reduction internal fixation (ORIF) with plating versus closed reduction and fixation using intramedullary nailing (IMN).

METHODS

The TriNetX database was queried using current procedural terminology (CPT) codes for surgical repair of femoral shaft fractures (FSFs), including IMN surgery (CPT: 27506) and femur ORIF (CPT: 27507). The subsequent chronological nonunion cases were identified using the 10th revision of the International Classification of Diseases (ICD-10) codes for femoral nonunion (S72.301K, S72.302K). Results were analyzed both descriptively and comparatively to assess differences among patients. Factors considered included age, sex, ethnicity, race, smoking status, and the type of surgical management (ORIF versus nailing) across the six-year study period.

RESULTS

From 2017 to 2022, the prevalence of femoral shaft fracture surgeries increased for both IMN and ORIF. The rate of nonunion was 2.1% following IMN and 1.7% following ORIF. The mean age for nonunion was 54 years (SD: 20) following IMN and 63 years (SD: 18) following ORIF. Patients with a positive smoking history had higher rates of nonunion compared to those without.

CONCLUSION

Our study revealed a relatively consistent rate of FSFs and nonunion over the six-year period. However, with a growing population, the absolute number of cases is steadily increasing, underscoring the burden on the healthcare system. This study contributes to the growing body of literature focused on improving patient outcomes and promoting health equity in fracture management practices.

Impact of osteoporosis and osteoporosis medications on fracture healing: a narrative review

Antiresorptive medications do not negatively affect fracture healing in humans. Teriparatide may decrease time to fracture healing. Romosozumab has not shown a beneficial effect on human fracture healing.

BACKGROUND

Fracture healing is a complex process. Uncertainty exists over the influence of osteoporosis and the medications used to treat it on fracture healing.

METHODS

Narrative review authored by the members of the Fracture Working Group of the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF), on behalf of the IOF and the Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT).

RESULTS

Fracture healing is a multistep process. Most fractures heal through a combination of intramembranous and endochondral ossification. Radiographic imaging is important for evaluating fracture healing and for detecting delayed or non-union. The presence of callus formation, bridging trabeculae, and a decrease in the size of the fracture line over time are indicative of healing. Imaging must be combined with clinical parameters and patient-reported outcomes. Animal data support a negative effect of osteoporosis on fracture healing; however, clinical data do not appear to corroborate with this. Evidence does not support a delay in the initiation of antiresorptive therapy following acute fragility fractures. There is no reason for suspension of osteoporosis medication at the time of fracture if the person is already on treatment. Teriparatide treatment may shorten fracture healing time at certain sites such as distal radius; however, it does not prevent non-union or influence union rate. The positive effect on fracture healing that romosozumab has demonstrated in animals has not been observed in humans.

CONCLUSION

Overall, there appears to be no deleterious effect of osteoporosis medications on fracture healing. The benefit of treating osteoporosis and the urgent necessity to mitigate imminent refracture risk after a fracture should be given prime consideration. It is imperative that new radiological and biological markers of fracture healing be identified. It is also important to synthesize clinical and basic science methodologies to assess fracture healing, so that a convergence of the two frameworks can be achieved.

Trends in Epidemiology and Treatment of Humerus Fractures in the United States, 2017-2022

Background Fractures of the humerus are one of the more common fractures in the United States and a cause of fragility fractures in the elderly population. This study aims to understand recent trends in the demographic factors correlated with humeral shaft fractures (HSF) and humeral shaft fracture nonunion (HSFN) following open reduction internal fixation (ORIF) and intramedullary nailing (IMN). Methods The TriNetX database was used to query using International Classification of Diseases-10 (ICD10) diagnosis codes for patients who sustained HSF between 2017 and 2022. Patients were then organized into cohorts based on Current Procedural Terminology (CPT) codes 24515 and 24516 for ORIF and IMN of HSFs, respectively. Subsequent nonunion after operative management was queried. Descriptive and comparative analysis was performed to examine the differences observed between patients based on age, sex, ethnicity, race, and smoking status as well as surgical management across the six-year study period. Results The incidence of HSF increased from 7,108 in 2017 to 8,450 in 2022. The rate of HSF ORIF increased from 12% to 17% while the nonunion rate following ORIF decreased from 4% to 3%. The rate of HSF IMN increased from 4% to 6% and the rate of nonunion following IMN increased from 2% to 4%. The overall rate of HSFN surgery was 1.7% with slight decreasing trend over the past year. Conclusion It is speculated that improved care and surgical indications resulted in a lower rate of nonunion despite an increase in the overall rate of HSF and its operative managements.

The Exosome-Mediated Bone Regeneration: An Advanced Horizon Toward the Isolation, Engineering, Carrying Modalities, and Mechanisms

Exosomes, nanoparticles secreted by various cells, composed of a bilayer lipid membrane, and containing bioactive substances such as proteins, nucleic acids, metabolites, etc., have been intensively investigated in tissue engineering owing to their high biocompatibility and versatile biofunction. However, there is still a lack of a high-quality review on bone defect regeneration potentiated by exosomes. In this review, the biogenesis and isolation methods of exosomes are first introduced. More importantly, the engineered exosomes of the current state of knowledge are discussed intensively in this review. Afterward, the biomaterial carriers of exosomes and the mechanisms of bone repair elucidated by compelling evidence are presented. Thus, future perspectives and concerns are revealed to help devise advanced modalities based on exosomes to overcome the challenges of bone regeneration. It is totally believed this review will attract special attention from clinicians and provide promising ideas for their future works.

Opioid-Sparing Nonsteroid Anti-inflammatory Drugs Protocol in Patients Undergoing Intramedullary Nailing of Tibial Shaft Fractures: A Randomized Control Trial

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective analgesics commonly used in fracture management. Although previously associated with delayed fracture healing, multiple studies have demonstrated their safety, with minimal risks of fracture healing. Given the current opioid crisis in the United States, alternate pain control modalities are essential to reduce opioid consumption. This study aims to determine whether the combination of oral acetaminophen and intravenous ketorolac is a viable alternative to opioid-based pain management in closed tibial shaft fractures treated with intramedullary nailing.

METHODS

We conducted a randomized controlled trial evaluating postoperative pain control and opioid consumption in patients with closed tibial shaft fractures who underwent intramedullary nailing. Patients were randomized into an NSAID-based pain control group (52 patients) and an opioid-based pain control group (44 patients). Visual analog scale (VAS) scores and morphine milligram equivalents (MMEs) were evaluated at 12-hour postoperative intervals during the first 48 hours after surgery. Nonunion and delayed healing rates were recorded for both groups.

RESULTS

A statistically significant decrease in MMEs was noted at every measured interval (12, 24, 36, and 48 hours) in the NSAID group compared with the opioid group ( P -value 0.001, 0.001, 0.040, 0.024, respectively). No significant change in visual analog scale scores was observed at 12, 36, and 48 hours between both groups ( P -value 0.215, 0.12, and 0.083, respectively). A significant decrease in VAS scores was observed at the 24-hour interval in the NSAID group compared with the opioid group ( P -value 0.041). No significant differences in union rates were observed between groups ( P -value 0.820).

DISCUSSION

Using an NSAID-based postoperative pain protocol led to a decrease in opioid consumption without affecting pain scores or union rates. Owing to the minimal risk of short-term NSAID use, their role in the perioperative management of tibia shaft fractures is justified, especially when they reduce opioid consumption markedly.

LEVEL OF EVIDENCE

Therapeutic Level I.

Technology Behind Cell Therapy Augmentation of Fracture Healing: Concentrated Bone Marrow Aspirate

With an aging population, and an anticipated increase in overall fracture incidence, a sound understanding of bone healing and how technology can optimize this process is crucial. Concentrated bone marrow aspirate (cBMA) is a technology that capitalizes on skeletal stem and progenitor cells (SSPCs) to enhance the regenerative capacity of bone. This overview highlights the science behind cBMA, discusses the role of SSPCs in bone homeostasis and fracture repair, and briefly details the clinical evidence supporting the use of cBMA in fracture healing. Despite promising early clinical results, a lack of standardization in harvest and processing techniques, coupled with patient variability, presents challenges in optimizing the use of cBMA. However, cBMA remains an emerging technology that may certainly play a crucial role in the future of fracture healing augmentation.

Increased β2-adrenergic signaling promotes fracture healing through callus neovascularization in mice

Traumatic brain injury (TBI) leads to skeletal changes, including bone loss in the unfractured skeleton, and paradoxically accelerates healing of bone fractures; however, the mechanisms remain unclear. TBI is associated with a hyperadrenergic state characterized by increased norepinephrine release. Here, we identified the β2-adrenergic receptor (ADRB2) as a mediator of skeletal changes in response to increased norepinephrine. In a murine model of femoral osteotomy combined with cortical impact brain injury, TBI was associated with ADRB2-dependent enhanced fracture healing compared with osteotomy alone. In the unfractured 12-week-old mouse skeleton, ADRB2 was required for TBI-induced decrease in bone formation and increased bone resorption. Adult 30-week-old mice had higher bone concentrations of norepinephrine, and ADRB2 expression was associated with decreased bone volume in the unfractured skeleton and better fracture healing in the injured skeleton. Norepinephrine stimulated expression of vascular endothelial growth factor A and calcitonin gene-related peptide-α (αCGRP) in periosteal cells through ADRB2, promoting formation of osteogenic type-H vessels in the fracture callus. Both ADRB2 and αCGRP were required for the beneficial effect of TBI on bone repair. Adult mice deficient in ADRB2 without TBI developed fracture nonunion despite high bone formation in uninjured bone. Blocking ADRB2 with propranolol impaired fracture healing in mice, whereas the ADRB2 agonist formoterol promoted fracture healing by regulating callus neovascularization. A retrospective cohort analysis of 72 patients with long bone fractures indicated improved callus formation in 36 patients treated with intravenous norepinephrine. These findings suggest that ADRB2 is a potential therapeutic target for promoting bone healing.

Surgical outcomes of anterior column reconstruction for spinal fractures caused by minor trauma-preoperative examination of the number of intervertebral bone bridges is key to obtaining good bone fusion

BACKGROUND

To achieve good bone fusion in anterior column reconstruction for vertebral fractures, not only bone mineral density (BMD) and bone metabolism markers but also lever arms due to bone bridging between vertebral bodies should be evaluated. However, until now, no lever arm index has been devised. Therefore, we believe that the maximum number of vertebral bodies that are bony and cross-linked with the contiguous adjacent vertebrae (maxVB) can be used as a measure for lever arms. The purpose of this study is to investigate the surgical outcomes of anterior column reconstruction for spinal fractures and to determine the effect of bone bridging between vertebral bodies on the rate of bone fusion using the maxVB as an indicator of the length of the lever arm.

METHODS

The clinical data of 81 patients who underwent anterior column reconstruction for spinal fracture between 2014 and 2022 were evaluated. The bone fusion rate, back pain score, between the maxVB = 0 and the maxVB ≥ 2 patients were adjusted for confounding factors (age, smoking history, diabetes mellitus history, BMD, osteoporosis drugs, surgical technique, number of fixed vertebrae, materials used for the anterior props, etc.) and analysed with multivariate or multiple regression analyses. The bone healing rate and incidence of postoperative back pain were compared among the three groups (maxVB = 0, 2≦maxVB≦8, maxVB ≧ 9) and divided by the maxVB after adjusting for confounding factors.

RESULTS

Patients with a maxVB ≥ 2 had a significantly higher bone fusion rate (p < 0.01) and postoperative back pain score (p < 0.01) than those with a maxVB = 0. Among the three groups, the bone fusion rate and back pain score were significantly higher in the 2≦maxVB≦8 group (p = 0.01, p < 0.01).

CONCLUSIONS

Examination of the maxVB as an indicator of the use of a lever arm is beneficial for anterior column reconstruction for vertebral fractures. Patients with no intervertebral bone bridging or a high number of bone bridges are in more need of measures to promote bone fusion than patients with a moderate number of bone bridges are.

Distal Radius Nonunions: A Rare Entity?

Although distal radius fractures are common injuries, nonunion is extremely rare. Nonunion has been associated with increased metaphyseal comminution, concomitant distal ulna fracture, inadequate immobilization, and patient factors. Nonunion should be suspected in patients with persistent pain, limited range of motion, and worsening wrist deformity after wrist remobilization. Treatment selection depends on presence of infection, status of the radiocarpal and distal radioulnar joints, and type of prior surgical interventions. Multiple surgical techniques exist for managing distal radius nonunions including open reduction and internal fixation of the nonunion site with/without bone graft augmentation versus total wrist arthrodesis.

Risk Factors for the Development of Persistent Scaphoid Non-Union After Surgery for an Established Non-Union

BACKGROUND

Between 2014 and 2020, candidates for scaphoid non-union (SNU) surgery were enrolled in a prospective randomized trial (Scaphoid Nonunion and Low Intensity Pulsed Ultrasound [SNAPU] trial) evaluating the effect of low-intensity pulsed ultrasound on postoperative scaphoid healing. At trial completion, 114/134 (85%) of these patients went on to union, and 20/134 (15%) went on to persistent SNU (PSNU). The purpose of this study was to use this prospectively gathered data to identify patient-, fracture-, and surgery-specific risk factors that may be predictive of PSNU in patients who undergo surgery for SNU.

METHODS

Data were extracted from the SNAPU trial database. The inclusion and exclusion criteria of this study were the same as that of the SNAPU trial. Nineteen patient-, fracture-, and surgery-specific risk factors were determined a priori. A stepwise multivariable logistic regression model was used to identify independent risk factors for PSNU.

RESULTS

Three risk factors were found to be independently significant predictors of PSNU: age at the time of surgery, dominant hand injury, and previous surgery on the affected scaphoid. With every decade of a patient's life, dominant hand injury, and previous scaphoid surgery, the odds of union are reduced by 1.72 times, 7.35 times, and 4.24 times, respectively.

CONCLUSION

We identified three independent risk factors for PSNU: age at SNU surgery, dominant hand injury, and previous surgery on the affected scaphoid. The findings of this study are significant and may contribute to shared decision-making and prognostication between the patient, surgeon, and affiliated members of their care team.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Association of Fracture Location and Pattern With Nonunion or Malunion in Tibia Fractures Managed With Intramedullary Nailing: A Retrospective Study

Background and objective Extra-articular fractures of the tibia are common orthopedic injuries that are frequently treated with rigid intramedullary nailing. Fracture location and pattern may increase the risk of nonunion or malunion in fractures managed with intramedullary nails. This study aimed to assess the relationship between fracture pattern and location with malunion and nonunion. The primary objective was to evaluate the influence of fracture location and pattern on adverse clinical outcomes such as nonunion, delayed union, and malunion in tibial shaft fractures that are treated operatively with rigid intramedullary nails. Methodology This was a retrospective cross-sectional study conducted on patients operated in a tertiary care center in the Kingdom of Bahrain. The study included patients who sustained tibia shaft fractures and were subsequently operated with intramedullary of the tibia. The primary endpoint was the rate of adverse outcomes associated with fracture patterns. Fracture characteristics were to determine which fracture patterns healed well with intramedullary nailing and which fractures ended up with malunion or nonunion and would likely benefit from additional measures to augment the nail fixation and help encourage union. Results One hundred and eighty-nine patients were included in the study. The level of associated fibula fracture was significantly associated with an increased risk of nonunion and malunion (P = 0.0034, P = 0.001). The presence of a concomitant distal fibula fracture in association with tibia fractures increased the odds of nonunion (odds ratio [OR] = 4.871, P = 0.033, confidence interval [CI] = 1.133-20.948). Conclusions The level and pattern of some tibia and fibula fractures were associated with nonunion, malunion, and delayed union. Further studies with more robust follow-up are needed to examine these findings in greater detail.

Familial Analysis of Nonunion in a Genealogic Population Database Demonstrates No Evidence of Heritable Risk

OBJECTIVE

To determine whether there is evidence of heritable risk for nonunion using a large, state-wide population database.

DESIGN

Database.

SETTING

Level 1 Trauma Center.

POPULATION

All Utah residents from 1996 to 2021 who sustained a long bone fracture and their family members were included.

OUTCOMES

The primary outcome was nonunion and the prevalence of nonunion among the patients' first-, second-, and third-degree relatives. The secondary objective was to identify demographic, injury, and socioeconomic risk factors associated with nonunion.

RESULTS

In total, 150,263 fractures and 6577 nonunions (4.4%) were identified. This was highly refined to a 1:3 matched cohort of 4667 nonunions of 13,981 fractures for familial clustering analysis. Cox proportional hazards did not demonstrate excessive risk of nonunion among first- ( P = 0.863), second- ( P = 0.509), and third-degree relatives ( P = 0.252). Further analysis of the entire cohort demonstrated that male sex (relative risk [RR] = 1.15; P < 0.001), Medicaid enrollment (RR = 2.64; P < 0.001), open fracture (RR = 2.53; P < 0.001), age group 41-60 years (RR = 1.43; P < 0.001), and a history of obesity (RR = 1.20; P < 0.001) were independent risk factors for nonunion.

CONCLUSIONS

Our results demonstrate no evidence of heritable risk for nonunion. Independent risk factors for nonunion were male sex, Medicaid enrollment, open fracture, middle age, and a history of obesity. Although it is important to identify modifiable and nonmodifiable risk factors, these results continue to support that the risk of nonunion is multifactorial, relating to injury characteristics, operative techniques, and patient-specific risk factors.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Number of contiguous vertebral cross-links in the spine indicates bone formation: a cross-sectional study

BACKGROUND

As an indicator to evaluate the risk of fracture in diffuse idiopathic skeletal hyperostosis, the maximum number of vertebral bodies' bone cross-linked with contiguous adjacent vertebrae (max VB) was developed. This study retrospectively investigates the relationship between max VB, bone mineral density (BMD), and bone metabolic markers (BMM).

METHODS

In this cross-sectional study (from April 2010 to January 2022), males (n = 114) with various max VB from the thoracic vertebra to the sacrum, measured using computed tomography scans, were selected to assess femur BMD and BMM. The association of max VB with the total type I procollagen N-terminal propeptide (P1NP), tartrate-resistant acid phosphatase 5b (TRACP-5b), and bone turnover ratio (BTR = TRACP-5b/P1NP) as well as its relationship with femur BMD with P1NP and TRACP-5b, were investigated. Furthermore, the relationship between P1NP and TRACP-5b was investigated.

RESULTS

P1NP increased in proportion to max VB and TRACP-5b increased in proportion to P1NP. Moreover, BTR was inversely proportional to max VB. Finally, femur BMD was inversely proportional to P1NP and TRACP-5b.

CONCLUSION

As max VB increased with P1NP-a potential osteogenesis indicator-and BTR was inversely proportional to max VB with compensatory TRACP-5b increase, max VB can be considered as a possible predictor of bone fusion.

Segmental defect healing in the presence or absence of recombinant human BMP2: Novel insights from a rat model

This study defined and compared the course of native, impaired and growth factor-stimulated bone regeneration in a rat femoral defect model. A mid-diaphyseal defect with rigid internal fixation was surgically created in the right femur of male Fischer rats and serially analyzed over 36 weeks. Native bone regeneration was modeled using a sub-critical, 1 mm size defect, which healed uneventfully. Critical size defects of 5 mm were used to analyze impaired bone regeneration. In a third group, the 5 mm defects were filled with 11 µg of recombinant human bone morphogenetic protein 2 (rhBMP2) impregnated onto an absorbable collagen sponge, modeling its clinical use. Native bone regeneration was characterized by endochondral ossification with progressive remodeling to ultimately resemble intact femora. An endochondral response was also observed under conditions of impaired bone regeneration, but by week 8 medullary capping occurred with fibrofatty consolidation of the tissue within the defect, resembling an atrophic non-union. rhBMP2 treatment was associated with prolonged inflammatory cytokine expression and rapid intramembranous bone formation occurring with reduced expression of cartilage-associated collagens. Between weeks 4 and 36, rhBMP2-treated bones demonstrated decreased trabecular number and increased trabecular separation, which resulted in inferior mechanical properties compared with bones that healed naturally. Clinical Significance: Recombinant human bone morphogenetic protein 2 (rhBMP2) is used clinically to promote healing of long bones. Our data suggest that it drives intramembraneous ossification producing an inferior regenerate that deteriorates with time. Clinical outcomes would be improved by technologies favoring endochondral regenerative ossification.

Correlation between Risk Factors and Healing Times in Long Bone Nonunions Treated with Corticoperiosteal Flap from the Medial Femoral Condyle

BACKGROUND

 The rate of fracture nonunion varies depending on the anatomical site. Numerous procedures have been proposed to treat recalcitrant nonunions. The vascularized medial femoral condyle corticoperiosteal free flap (MFCCFF) is increasingly used in nonunions with small bone loss.The percentage of success of the MFCCFF is high but the factors involved in delayed bone healing or failure of this technique or the contraindications are not described in the literature.This multicentric study aims to identify and report the different factors involved in determining the time of bone healing in the treatment of atrophic nonunion of long bones with the vascularized medial MFCCFF.

METHODS

 All patients who underwent vascularized medial MFCCFF from January 2011 to December 2020 for the treatment of recalcitrant atrophic nonunions of long bones. Patients were reviewed at 2 and 6 weeks, and 3, 6, and 12 months postoperatively and evaluated by physical and radiographic examinations and patient-reported outcome measures.

RESULTS

 The final study population comprised 59 patients with a mean follow-up of 26.2 ± 7.6 months, a rate of bone healing of 94.9% with a mean radiographic bone healing time of 4.1 ± 1.3 months, and low morbidity of the donor site. Diabetes mellitus, a body mass index (BMI) ≥30 kg/m2, and ≥2 previous surgeries on the fracture site were factors predicting timing for bone healing at the multivariate analysis.

CONCLUSION

 This study demonstrates the MFCCFF as an effective and safe procedure for the treatment of the recalcitrant atrophic nonunion of long bones. An association was found between the lengthening of bone healing time and a high BMI, presence of ≥2 previous surgical interventions, and diabetes mellitus, indicating these comorbidities as risk factors (not absolute contraindications) for this microsurgical treatment. So, to our knowledge, the MFCCFF could be the first-choice treatment for atrophic nonunion of long bones.

Increased beta2-adrenergic signaling is a targetable stimulus essential for bone healing by promoting callus neovascularization

Traumatic brain injury (TBI) is associated with a hyperadrenergic state and paradoxically causes systemic bone loss while accelerating fracture healing. Here, we identify the beta2-adrenergic receptor (Adrb2) as a central mediator of these skeletal manifestations. While the negative effects of TBI on the unfractured skeleton can be explained by the established impact of Adrb2 signaling on bone formation, Adrb2 promotes neovascularization of the fracture callus under conditions of high sympathetic tone, including TBI and advanced age. Mechanistically, norepinephrine stimulates the expression of Vegfa and Cgrp primarily in periosteal cells via Adrb2, both of which synergistically promote the formation of osteogenic type-H vessels in the fracture callus. Accordingly, the beneficial effect of TBI on bone repair is abolished in mice lacking Adrb2 or Cgrp, and aged Adrb2-deficient mice without TBI develop fracture nonunions despite high bone formation in uninjured bone. Pharmacologically, the Adrb2 antagonist propranolol impairs, and the agonist formoterol promotes fracture healing in aged mice by regulating callus neovascularization. Clinically, intravenous beta-adrenergic sympathomimetics are associated with improved callus formation in trauma patients with long bone fractures. Thus, Adrb2 is a novel target for promoting bone healing, and widely used beta-blockers may cause fracture nonunion under conditions of increased sympathetic tone.

Abstract Figure

Extracorporeal shock wave treatment for post‑surgical fracture nonunion: Insight into its mechanism, efficacy, safety and prognostic factors (Review)

Post-surgical fracture nonunion (PSFN) represents the failure to achieve cortical continuity at radiological examination after an orthopedic operation, which causes a considerable disease burden in patients with fractures. As one of the traditional treatment modalities, surgical therapy is associated with a high fracture union rate; however, post-surgical complications are not negligible. Therefore, less invasive therapies are needed to improve the prognosis of patients with PSFN. Extracorporeal shock wave treatment (ESWT) is a noninvasive method that presents a similar efficacy profile and favorable safety profile compared with surgical treatment. However, the application and detailed mechanism of ESWT in patients with PSFN remain unclear. The present review focuses on the mechanism, efficacy, safety and prognostic factors of ESWT in patients with PSFN, aiming to provide a theoretical basis for its application and improve the prognosis of these patients.

Factors Informing the Development of a Clinical Pathway and Patients' Quality of Life after a Non-Union Fracture of the Lower Limb

Patients with non-union fractures spend extended periods of time in the hospital following poor healing. Patients have to make several follow-up visits for medical and rehabilitation purposes. However, the clinical pathways and quality of life of these patients are unknown. This prospective study aimed to identify the clinical pathways (CPs) of 22 patients with lower-limb non-union fractures whilst determining their quality of life. Data were collected from hospital records from admission to discharge, utilizing a CP questionnaire. We used the same questionnaire to track patients' follow-up frequency, involvement in activities of daily living, and final outcomes at six months. We used the Short Form-36 questionnaire to assess patients' initial quality of life. The Kruskal-Wallis test compared the quality of life domains across different fracture sites. We examined CPs using medians and inter-quantile ranges. During the six-month follow-up period, 12 patients with lower-limb non-union fractures were readmitted. All of the patients had impairments, limited activity, and participation restrictions. Lower-limb fractures can have a substantial impact on emotional and physical health, and lower-limb non-union fractures may have an even greater effect on the emotional and physical health of patients, necessitating a more holistic approach to patient care.

No Increased Risk of Nonunion with Bisphosphonate Use in a Medicare Claims Cohort Following Operatively Treated Long-Bone Fractures

BACKGROUND

The diagnosis of a fragility fracture represents an important intervention event for the initiation of medical osteoporosis treatments. However, it is unclear if osteoporosis medications increase the risk of nonunion if administered in the setting of acute fracture. The purpose of the present study was to investigate whether bisphosphonates or selective estrogen receptor modulators/hormone replacement therapy (SERM/HRT) are associated with nonunion following fracture in a Medicare population.

METHODS

A retrospective analysis of Medicare claims from 2016 to 2019 was performed to identify patients ≥65 years of age who had a surgically treated long-bone fracture as identified with Current Procedural Terminology (CPT) codes and International Classification of Diseases, 10th Revision (ICD-10) codes. Successive claims were linked for each beneficiary through 1 year following the fracture to determine fracture union status. Multivariable logistic regression models were specified to identify the association between medications and fracture union status while controlling for age, sex, race, Charlson Comorbidity Index (CCI), and fracture type.

RESULTS

Of the 111,343 included fractures, 10,452 (9.4%) were associated with a diagnosis of nonunion within 1 year. The nonunion group was younger (79.8 ± 8.3 versus 80.6 ± 8.4 years; p < 0.001), more likely to be White (92.4% versus 90.9%; p < 0.001), and more likely to have a CCI of ≥2 (50.9% versus 49.4%; p < 0.001). Bisphosphonate use was more common in the nonunion group (12.2% versus 11.4%; p = 0.017). When controlling for race, age, sex, and CCI, neither bisphosphonates (OR, 1.06 [95% CI, 0.99 to 1.12]; p = 0.101) nor SERM/HRT (OR, 1.13 [0.93 to 1.36]; p = 0.218) were associated with nonunion. Bisphosphonate use within 90 days post-fracture was not significantly associated with nonunion (OR, 0.94 [95% CI, 0.86 to 1.03]; p = 0.175), and the timing of medication administration did not influence fracture union status.

CONCLUSIONS

The rate of nonunion after operatively treated long-bone fractures was 9.4%. In this cohort, use of a bisphosphonate or SERM/HRT was not associated with fracture union status at 1 year. Orthopaedic surgeons should not withhold or delay initiating medical therapies for osteoporosis in the setting of acute fracture out of concern for nonunion.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Reambulation following hindlimb unloading attenuates disuse-induced changes in murine fracture healing

Patients with bone and muscle loss from prolonged disuse have higher risk of falls and subsequent fragility fractures. In addition, fracture patients with continued disuse and/or delayed physical rehabilitation have worse clinical outcomes compared to individuals with immediate weight-bearing activity following diaphyseal fracture. However, the effects of prior disuse followed by physical reambulation on fracture healing cellular processes and adjacent bone and skeletal muscle recovery post-injury remains poorly defined. To bridge this knowledge gap and inform future treatment and rehabilitation strategies for fractures, a preclinical model of fracture healing with a history of prior unloading with and without reambulation was employed. First, skeletally mature male and female C57BL/6J mice (18 weeks) underwent hindlimb unloading by tail suspension (HLU) for 3 weeks to induce significant bone and muscle loss modeling enhanced bone fragility. Next, mice had their right femur fractured by open surgical dissection (stabilized with 24-gauge pin). The, mice were randomly assigned to continued HLU or allowed normal weight-bearing reambulation (HLU + R). Mice given normal cage activity throughout the experiment served as healthy age-matched controls. All mice were sacrificed 4-days (DPF4) or 14-days (DPF14) following fracture to assess healing and uninjured hindlimb musculoskeletal properties (6-10 mice per treatment/biological sex). We found that continued disuse following fracture lead to severely diminished uninjured hindlimb skeletal muscle mass (gastrocnemius and soleus) and femoral bone volume adjacent to the fracture site compared to healthy age-matched controls across mouse sexes. Furthermore, HLU led to significantly decreased periosteal expansion (DPF4) and osteochondral tissue formation by DPF14, and trends in increased osteoclastogenesis (DPF14) and decreased woven bone vascular area (DPF14). In contrast, immediate reambulation for 2 weeks after fracture, even following a period of prolonged disuse, was able to increase hindlimb skeletal tissue mass and increase osteochondral tissue formation, albeit not to healthy control levels, in both mouse sexes. Furthermore, reambulation attenuated osteoclast formation seen in woven bone tissue undergoing disuse. Our results suggest that weight-bearing skeletal loading in both sexes immediately following fracture may improve callus healing and prevent further fall risk by stimulating skeletal muscle anabolism and decreasing callus resorption compared to minimal or delayed rehabilitation regimens.

Operative treatment of nonunions in the elderly: Clinical and radiographic outcomes in patients at minimum 75 years of age

BACKGROUND

Limited information exists on nonunion treatment in the elderly. This retrospective study evaluates whether results of operative treatment of nonunion of the humerus or femur in patients aged ≥ 75 years are comparable to those in younger patients.

METHODS

We identified patients age ≥ 75 years with a nonunion of humerus or femur treated with open reduction and internal fixation. The Non-Union Scoring System was calculated. Complications, clinical outcome, and radiographic findings were assessed. Primary endpoint was nonunion healing. A literature review compared time to healing of humeral and femoral nonunion in younger populations.

RESULTS

We identified 45 patients treated for a nonunion of humerus or femur with > 12 months follow-up. Median age was 79 years (range 75-96). Median time to presentation was 12 months (range 4-127) after injury, median number of prior surgeries was 1 (range 0-4). Union rate was 100%, with median time to union 6 months (range 2-42). Six patients underwent revision for persistent nonunion and healed without further complications.

CONCLUSIONS

Using a protocol of debridement, alignment, compression, stable fixation, bone grafting and early motion, patients aged 75 years or older can reliably achieve healing when faced with a nonunion of the humerus or femur.

LEVEL OF EVIDENCE

IV.

Induced Membrane Technique for the Management of Segmental Femoral Defects: A Systematic Review and Meta-Analysis of Individual Participant Data

Several modifications of the induced membrane technique (IMT) have been reported, but there is no consensus regarding their results and prognosis. Moreover, most studies have focused on tibial defects; no meta-analysis of the treatment of femoral defects using the IMT has been reported. This systematic review and meta-analysis aimed to identify the potential risk factors of post-procedural complications following the treatment of segmental femoral defects using the IMT. A comprehensive search was performed on the Cochrane Library, EBSCO, EMBASE, Ovid, PubMed, Scopus, and Web of Science databases, using the keywords "femur," "Masquelet technique," and "induced membrane technique." Original articles composed in English, having accessible individual patient data, and reporting more than two cases of bony defect or nonunion of femur or more than five cases of any body part were included. Post-procedural bone graft infections, final union status, and union time after second-stage operation were analyzed. Fourteen reports, including 90 patients, were used in this study. External fixation in second-stage surgery had an odds ratio of 9.267 for post-procedural bone graft infection (p = 0.047). The odds ratio of post-procedural bone graft infection and age >65 years for final non-union status was 51.05 (p = 0.003) and 9.18 (p = 0.042). Shorter union time was related to impregnated antibiotics in the spacer (p = 0.005), transplanting all-autologous grafts (p = 0.042), and the application of intramedullary nails as the second-stage fixation method (p = 0.050). The IMT appears to be reasonable and reproducible for femoral segmental bone defects. Several preoperative and surgical factors may affect post-procedural complications and union time.

Fracture Healing in the Setting of Endocrine Diseases, Aging, and Cellular Senescence

More than 2.1 million age-related fractures occur in the United States annually, resulting in an immense socioeconomic burden. Importantly, the age-related deterioration of bone structure is associated with impaired bone healing. Fracture healing is a dynamic process which can be divided into four stages. While the initial hematoma generates an inflammatory environment in which mesenchymal stem cells and macrophages orchestrate the framework for repair, angiogenesis and cartilage formation mark the second healing period. In the central region, endochondral ossification favors soft callus development while next to the fractured bony ends, intramembranous ossification directly forms woven bone. The third stage is characterized by removal and calcification of the endochondral cartilage. Finally, the chronic remodeling phase concludes the healing process. Impaired fracture healing due to aging is related to detrimental changes at the cellular level. Macrophages, osteocytes, and chondrocytes express markers of senescence, leading to reduced self-renewal and proliferative capacity. A prolonged phase of "inflammaging" results in an extended remodeling phase, characterized by a senescent microenvironment and deteriorating healing capacity. Although there is evidence that in the setting of injury, at least in some tissues, senescent cells may play a beneficial role in facilitating tissue repair, recent data demonstrate that clearing senescent cells enhances fracture repair. In this review, we summarize the physiological as well as pathological processes during fracture healing in endocrine disease and aging in order to establish a broad understanding of the biomechanical as well as molecular mechanisms involved in bone repair.

Transcriptome Sequencing Analysis of lncRNA and mRNA Expression Profiles in Bone Nonunion

Background

Bone nonunion is a serious complication of fracture. This study explored the differentially expressed lncRNAs (DELs) and mRNAs (DEGs) and identified potential lncRNA-mRNA interactions in bone nonunion.

Methods

We extracted total RNA from three bone nonunion and three bone union patient tissue samples. RNA sequencing was performed to detect DELs and DEGs between bone nonunion and union tissue samples. The lncRNAs and genes with absolute log2-fold change (log2FC) > 1 and adjusted p value < 0.05 were further chosen for gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. lncRNA and targeted mRNA interaction networks were constructed.

Results

We observed 179 DELs and 415 DEGs between the bone nonunion and union tissue samples. GO analysis indicated that DELs and DEGs were mainly enriched in the chondroitin sulfate proteoglycan biosynthetic process. DELs and DEGs were enriched in “ECM-receptor interaction” and “Staphylococcus aureus infection” KEGG pathways. Several potential lncRNA-mRNA interactions were also predicted.

Conclusions

This study identified bone nonunion-associated lncRNAs and mRNAs using deep sequencing that may be useful as potential biomarkers for bone nonunion.

Kinematic parameters after tibial nonunion treatment using the Ilizarov method

Background

Analysis of the outcomes of Ilizarov treatment of tibial nonunion shows functional deficits in the lower limbs of some patients. Biomechanical gait parameters are an important measure for assessing musculoskeletal disorder treatments that aim to restore normal gait. The purpose of our study was to compare the kinematic parameters in patients with tibial nonunion treated using the Ilizarov method and those in a control group of healthy volunteers.

Methods

The study population consisted of 23 patients (age 54.9 ± 16.4 years) who were treated for tibial nonunion using the Ilizarov method, as well as 22 healthy adult controls (age 52.7 ± 10.6 years). Kinematic parameters were measured using a Noraxon MyoMOTION System. We measured hip flexion and abduction, knee flexion, ankle dorsiflexion, inversion, and abduction during walking.

Results

Our analysis showed significant differences between the patients’ operated limbs (OLs) and the controls’ nondominant limbs (NDLs) in the ranges of hip flexion, hip abduction, and knee flexion. We observed no significant differences in knee flexion between the OL and the NOL in patients or between the dominant limb (DL) and NDL in controls. Our evaluation of the kinematic parameters of the ankle joint demonstrated significant differences between the patients’ OLs and the controls’ NDLs in the ranges of ankle dorsiflexion, ankle inversion, and ankle abduction. There were also significant differences in the range of ankle dorsiflexion and ankle abduction between the patients’ NOLs and the controls’ DLs.

Conclusion

Tibial nonunion treatment using the Ilizarov method does not ensure complete normalization of kinematic parameters assessed 24–48 months following the completion of treatment and rehabilitation.

Forearm Fracture Nonunion with and without Bone Loss: An Overview of Adult and Child Populations

Nonunion occurs in 2-10% of all forearm fractures due to different mechanical and biological factors, patient characteristics, and surgeon-dependent causes. It is a condition that causes functional and psychosocial disability for the patient because it is a unique anatomical segment in which all the bones and structures involved embody a complex functional unit; therefore, it is a challenge for the orthopedic surgeon. The ultimate goal of the care of these patients is the restoration of function and limitations related to impairment and disability. The aim of this review is to provide an extended description of nonunion forearm fractures, related risk factors, diagnosis, classification systems, and the available evidence for different types of treatment as a tool to better manage this pathology.

Episodic alcohol exposure attenuates mesenchymal stem cell chondrogenic differentiation during bone fracture callus formation

BACKGROUND

During bone fracture repair, mesenchymal stem cells (MSC) differentiate into chondrocytes and osteoblasts to form a fracture callus. Our laboratory previously reported that alcohol-exposed rodents with a surgically created tibia fracture display deficient fracture callus formation and diminished signs of endochondral ossification characterized by the absence of chondrocytes and mature hypertrophic chondrocytes, suggesting that alcohol may inhibit MSC differentiation. These findings led to our hypothesis that alcohol exposure inhibits mesenchymal stem cell chondrogenic differentiation within the developing fracture callus.

METHODS

In the present study, we utilized a lineage-tracing approach to determine which stage(s) of chondrogenic differentiation are affected by alcohol exposure. We utilized lineage-specific reporter mice to determine the effects of alcohol on MSC and early and late chondrogenic cell frequencies within the fracture callus. In addition, serially sectioned slides were stained immunofluorescently and immunohistochemically and quantified to determine the effect of alcohol on cell proliferation and apoptosis, respectively, within the fracture callus of alcohol-administered rodents.

RESULTS

Alcohol-administered rodents had a reduced fracture callus area at 4, 6, and 9 days postfracture. Alcohol had no effect on apoptosis in the fracture callus at any of the examined timepoints. Alcohol-administered rodents had significantly fewer proliferative cells in the fracture callus at 9 days postfracture, but no effect on cell proliferation was observed at earlier fracture callus timepoints. Alcohol-administered rodents had reduced Collagen2a1- and Collagen10a1-expressing cells in the developing fracture callus, suggesting that alcohol inhibits both early chondrogenic differentiation and later chondrocyte maturation during fracture callus development.

CONCLUSION

The data suggest that alcohol could affect normal fracture healing through the mitigation of MSC chondrogenic differentiation at the callus site.

Nonunions and Their Operative Treatment

BACKGROUND

Nonunions, which arise as a complication of fractures, are an impor - tant medical and socio-economic problem. The goal of this study was to analyze nonunions in Germany with respect to the patients' age and sex, the anatomical site of the lesions, and their operative treatment.

METHODS

The study was performed on the basis of DRG (diagnosis-related group) data acquired for billing purposes and collected by the German Federal Statistical Office. The administrative frequencies of nonunions and fractures treated in the inpatient setting, broken down by sex and age group, were calculated from the documentation of ICD codes. An investigation was also made of surgical treatments for nonunion, as they were categorized by the German procedure classification (Operationen- und Prozedurenschlüssel, OPS).

RESULTS

The administrative frequency of nonunion was 14.84 per 100 000 persons per year, with a 2% decline in case numbers over the period 2007-2019. Nonunions develop in 2% of fractures. Nonunions affect men more often than women (58% vs. 42%). In men, their incidence as a function of age is highest under age 30; in women, it rises steadily with increasing age. The most common type of surgical treatment is a combination of resection, bone transplantation, and osteosynthesis.

CONCLUSION

This is the first detailed nationwide study of diagnoses of nonunions in Germany and their surgical treatment. Despite a slow decline in their incidence, nonunions remain an important problem in the inpatient setting. The risk profile for nonunions is sex-, age-, and site-specific.

Risk Factors and Consequences of Lower Extremity Fracture Nonunions in Veterans With Spinal Cord Injury

We used Veterans Health Administration (VHA) national administrative data files to identify a cohort (fiscal years 2005–2014) of veterans with spinal cord injuries and disorders (SCID) to determine risk factors for and consequences of lower extremity fracture nonunions. Odds ratios (OR) for fracture nonunion were computed using multivariable‐adjusted logistic regression models. We identified three risk factors for nonunion: (i) older age (OR = 2.29; 95% confidence interval [CI] 1.21–4.33), (ii) longer duration of SCID (OR = 1.02; 95% CI 1.00–1.04), and (iii) fracture site (distal femur), with OR (comparison distal femur) including distal tibia/fibula (OR = 0.14; 95% CI 0.09–0.24), proximal tibia/fibula (OR = 0.19; 95% CI 0.09–0.38), proximal femur (OR = 0.10; 95% CI 0.04–0.21), and hip (OR = 0.13; 95% CI 0.07–0.26). Nonunions resulted in multiple complications, with upwards of 1/3 developing a pressure injury, 13% osteomyelitis, and almost 25% requiring a subsequent amputation. Our data have identified a high‐risk population for fracture nonunion of older veterans with a long duration of SCID who sustain a distal femur fracture. In view of the serious complications of these nonunions, targeted interventions in these high‐risk individuals who have any signs of delayed union should be considered. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Analysis of Risk Factors for Non-union After Surgery for Limb Fractures: A Case-Control Study of 669 Subjects

Objective: The purpose of this study was to analyze the risk factors for limb fracture non-union in order to improve non-union prevention and early detection.

Methods: A total of 223 patients with non-union after surgery for limb fractures performed at our institution from January 2005 to June 2017 were included as the case group, while a computer-generated random list was created to select 446 patients with successful bone healing after surgery for limb fractures who were treated during the same period as the control group, thus achieving a ratio of 1:2. The medical records of these patients were reviewed retrospectively. Age, sex, body mass index, obesity, smoking, alcohol, diabetes, hypertension, osteoporosis, fracture type, multiple fractures, non-steroidal anti-inflammatory drugs (NSAIDs) use, delayed weight bearing, internal fixation failure, and infection data were analyzed and compared between the two groups. A multivariate logistic regression model was constructed to determine relevant factors associated with non-union.

Results: After comparison between two groups by univariate analysis and multivariate logistic regression, we found some risk factors associated that osteoporosis (odds ratio [OR] = 3.16, 95% confidence interval [CI]: 2.05–4.89, p < 0.001), open fracture (OR = 2.71, 95%CI: 1.72–4.27, p < 0.001), NSAIDs use (OR = 2.04, 95%CI: 1.24–3.37, p = 0.005), delayed weight bearing (OR = 1.72, 95%CI: 1.08–2.74, p = 0.023), failed internal fixation (OR = 5.93, 95%CI: 2.85–12.36, p < 0.001), and infection (OR = 6.77, 95%CI: 2.92–15.69, p < 0.001) were independent risk factors for non-union after surgery for limb fractures.

Conclusions: Osteoporosis, open fracture type, NSAIDs use, delayed weight bearing, failed internal fixation, and infection were found to be the main causes of bone non-union; clinicians should, therefore, take targeted measures to intervene in high-risk groups early.

COMPARISON OF SINGLE- AND DOUBLE-PLATE FIXATION TECHNIQUES IN THE TREATMENT OF NONUNIONS OF THE HUMERAL SHAFT

Introduction

Humerus shaft fractures may be treated conservatively or surgically. In 2.5% to 13% of cases, nonunion is observed, and it leads to severe pain and morbidity. Plate osteosynthesis has become popular in the treatment of nonunion of the humeral shaft. In this study, we compared the clinical outcomes of patients with humerus shaft nonunion whom we treated with single- or double-plate fixation.

Materials and Methods

Fifty-three patients diagnosed with aseptic humeral shaft nonunion and treated with plate fixation were included in the study. Patients were evaluated according to the number of plates (single vs. double plates). The two groups were subjected to statistical evaluation according to their clinical and radiographical results.

Results

The average age of the patients was 53 years (range: 1-86); 28 (52.8%) were female and 25 (47.2%) were male. The union rate was 90.32% for single plate and 90.91% for double plate fixation. There was no statistically significant difference between single and double plates in the clinical and radiographical results (union time, union rate, Q-DASH score) (p > 0.05). There was a significant correlation between age and union times / Q-DASH scores according to the Spearman correlation test (p < 0.05). Transient radial nerve neuropraxia developed in 2 patients and 1 patient suffered from an infection that was treated with debridement and antibiotic therapy.

Conclusion

In our study, similar good results were obtained with single and double plates. In treatment of humeral shaft nonunions, a second plate is not needed if enough stability is provided with single plate fixation. Level of evidence III, Retrospective comparative study.

The effect of osteoporosis and its treatment on fracture healing a systematic review of animal and clinical studies

Introduction

Osteoporosis is characterised by low bone mass and micro-architectural deterioration of bone structure. Its treatment is directed at the processes of bone formation or resorption, that are of utmost importance in fracture healing. We provide a comprehensive review of the literature aiming to summarize and clarify the effects of osteoporosis and its treatment on fracture healing.

Material and methods

A literature search was conducted in PubMed and Embase (OVID version). In vivo animal and human studies on long bone fractures were included. A total of 93 articles were included for this review; 23 studies on the effect of osteoporosis (18 animal and 5 clinical studies) and 70 studies on the effect of osteoporosis treatment (41 animal, 26 clinical studies and 3 meta-analyses) on fracture healing.

Results

In animal fracture models osteoporosis was associated with decreased callus formation and bone growth, bone mineral density, biomechanical strength and delayed cellular and differentiation processes during fracture healing. Two large databases identified osteoporosis as a risk factor for non-union whereas three other studies did not. One of those three studies however found a prolonged healing time in patients with osteoporosis. Anti-osteoporosis medication showed inconsistent effects on fracture healing in both non-osteoporotic and osteoporotic animal models. Only the parathyroid hormone and anti-resorption medication were related to improved fracture healing and delayed remodelling respectively. Clinical studies performed in predominantly hip and distal radius fracture patients showed no effect of bisphosphonates on fracture healing. Parathyroid hormone reduced time to union in several clinical trials performed in mainly hip fracture patients, but this did not result in decreased delayed or non-union rates.

Conclusion

Evidence that substantiates the negative influence of osteoporosis on fracture healing is predominantly from animal studies and to a lesser extent from clinical studies, since convincing clinical evidence lacks. Bisphosphonates and parathyroid hormone may be used during fracture healing, since no clear negative effect has been shown. Parathyroid hormone might even decrease time to fracture union, without decreasing union rate.

•

Osteoporosis negatively influences fracture healing in animal models.

•

There is no convincing evidence for a similar effect in humans.

•

In animals, bisphosphonates delay bone remodelling

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In animals, parathyroid hormone improves fracture healing

•

In humans, anti-osteoporotic drugs do not interfere with fracture healing.

Non-union bone fractures

The human skeleton has remarkable regenerative properties, being one of the few structures in the body that can heal by recreating its normal cellular composition, orientation and mechanical strength. When the healing process of a fractured bone fails owing to inadequate immobilization, failed surgical intervention, insufficient biological response or infection, the outcome after a prolonged period of no healing is defined as non-union. Non-union represents a chronic medical condition not only affecting function but also potentially impacting the individual's psychosocial and economic well-being. This Primer provides the reader with an in-depth understanding of our contemporary knowledge regarding the important features to be considered when faced with non-union. The normal mechanisms involved in bone healing and the factors that disrupt the normal signalling mechanisms are addressed. Epidemiological considerations and advances in the diagnosis and surgical therapy of non-union are highlighted and the need for greater efforts in basic, translational and clinical research are identified.

Do Nonsteroidal Anti-Inflammatory or COX-2 Inhibitor Drugs Increase the Nonunion or Delayed Union Rates After Fracture Surgery?: A Propensity-Score-Matched Study

BACKGROUND

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs)/cyclooxygenase (COX)-2 inhibitors on postoperative fracture-healing are controversial. Thus, we investigated the association between NSAID/COX-2 inhibitor administration and postoperative nonunion or delayed union of fractures. We aimed to determine the effects of NSAID/COX-2 inhibitor administration on postoperative fracture-healing with use of a common data model.

METHODS

Patients who underwent operative treatment of a fracture between 1998 and 2018 were included. To determine the effects of NSAID/COX-2 inhibitor administration on fracture-healing, postoperative NSAID/COX-2 inhibitor users were compared and 1:1 matched to nonusers, with 3,264 patients matched. The effect of each agent on bone-healing was determined on the basis of the primary outcome (nonunion/delayed union), defined as having a diagnosis code for nonunion or delayed union ≥6 months after surgery. The secondary outcome was reoperation for nonunion/delayed union. To examine the effect of NSAIDs/COX-2 inhibitors on bone union according to medication duration, a Kaplan-Meier survival analysis was performed.

RESULTS

Of the 8,693 patients who were included in the analysis, 208 had nonunion (178 patients; 2.05%) or delayed union (30 patients; 0.35%). Sixty-four (30.8%) of those 208 patients had a reoperation for nonunion or delayed union. NSAID users showed a significantly lower hazard of nonunion compared with the matched cohort of nonusers (hazard ratio, 0.69 [95% confidence interval, 0.48 to 0.98]; p = 0.040) but did not show a significant difference in the other matched comparison for any other outcomes. Kaplan-Meier survival analysis revealed significantly lower and higher nonunion/delayed union rates when the medication durations were ≤3 and >3 weeks, respectively (p = 0.001). For COX-2 inhibitors, the survival curve according to the medication duration showed no significant difference among the groups (p = 0.9).

CONCLUSIONS

Our study demonstrated no short-term impact of NSAIDs/COX-2 inhibitors on long-bone fracture-healing. However, continued use of these medications for a period of >3 weeks may be associated with higher rates of nonunion or delayed union.

LEVEL OF EVIDENCE

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

Systemically impaired fracture healing in small animal research: A review of fracture repair models

Fracture healing is a complex process requiring mechanical stability, an osteoconductive matrix, and osteoinductive and osteogenic biology. This intricate process is easily disrupted by various patient factors such as chronic disease and lifestyle. As the medical complexity and age of patients with fractures continue to increase, the importance of developing relevant experimental models is becoming paramount in preclinical research. The objective of this review is to describe the most common small animal models of systemically impaired fracture healing used in the orthopedic literature including osteoporosis, diabetes mellitus, smoking, alcohol use, obesity, and ageing. This review will provide orthopedic researchers with a summary of current models of systemically impaired fracture healing used in small animals and present an overview of the methods of induction for each condition.

Epidemiology of long bone non-unions in Spain

Epidemiological and ecological studies on long bone non-unions (NU) are scarce, based on different populations and methodologies. The aim of this study was to produce a descriptive analysis of the femur, tibia, and humerus non-union epidemiology in Spain. Methods Data were obtained from the Minimum Basic Data (Conjunto Mínimo Básico de Datos, CMBD) Hospital Discharge Database of the Spanish Ministry of Health, according to the ICD9-CM coding for diagnoses and procedures, and from the National Institute of Statistics for population, generating secondary databases with the reported cases that included the code 733.82 in a disaggregated manner, by age (categorized in 5 intervals), gender, Spanish region, and calendar year (1997-2015). Percentage of non-unions related to fractures in the previous year, annual prevalence (expressed per 100,000 person-years) and period prevalence (expressed per 100,000 person-period) were calculated by age, gender, and Spanish regions. The Odds ratio (OR) was estimated with a confidence of 95% using a logistic regression model per anatomical site. Results A mean of 235,446 fractures in all locations were annually reported in Spain from 1997 to 2015. Regarding non-union of long bones (femur, tibia and humerus), a total of 37,053 cases were found, representing a yearly mean of 1,950 cases. The proportion of long bone fractures that evolved into a non-union was 4% (1.4% femur, 1.5% tibia, and 1% humerus). The mean annual prevalence rate of NU in Spain was estimated in 4.5 (3.7-4.9) cases per 100,000 persons-year. The overall NU prevalence in Spain was estimated in 86 cases per 100,000 persons. By the type of bone, the period prevalence (per 100,000 persons-period) of the femur NU was 31, of the tibia 33, and of the humerus 22. Conclusions This description of the epidemiology of long bone non-unions in Spain confirms that the overall non-union rate has been stable from 2000 to 2015, higher in the tibia and in the femur compared to the humerus. NU occurred more frequently in aged females than in males in the femur and the humerus, while the tibia non-unions were more frequent in males and younger age.

Low intensity pulsed ultrasound (LIPUS) use for the management of instrumented, infected, and fragility non-unions: a systematic review and meta-analysis of healing proportions

Background

Non-union occurs in approximately 5 to 10% of fracture patients, with certain bones at greater risk of failing to heal. Non-unions have a significant impact on socioeconomic costs and the patients short and long-term quality of life. Low intensity pulsed ultrasound (LIPUS) is a non-invasive therapy for non-union treatment that can improve the long-term outcome. The purpose of this study is to summarize the available literature assessing LIPUS potential to improve the union rate in instrumented, infected, and fragility non-unions.

Methods

A literature search was conducted in the MEDLINE, EMBASE, and CINAHL databases for all relevant literature on the healing rates of LIPUS utilized in instrumented, infected, and fragility non-unions. Study characteristics were summarized for each of the included studies. The percentage of healed patients (healing rate), for instrumented, infected, and fragility fracture non-union patients were pooled from each included study.

Results

The literature search identified a total of 326 articles, while searching reference lists and grey literature identified an additional 3 articles. There was a total of 29 articles included in this review, with 20 articles included within the quantitative synthesis of healing rates. The most common design of included studies was case series (17 articles), followed by case reports (9 articles). Studies were primarily retrospective (18 studies), with an additional 10 prospective studies. Non-union healing rates were 82% (95% CI: 76 to 87%) in instrumented, 82% (95% CI: 70 to 95%) in infected, and 91% (95% CI: 87 to 95%) in fragility fracture patients with non-unions.

Conclusion

This study has provided a thorough overview of the current literature on LIPUS treatment for instrumented, infected, and fragility fracture non-unions. The healing rates for non-unions in these subgroups were comparable to healing rates observed with LIPUS use in general non-union literature. LIPUS treatment should be considered as a conservative non-surgical treatment option to potentially reduce the socioeconomic impact and improve the quality of life of these unfortunate patients.

Level of evidence

4 (systematic review of primarily case series data)

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04322-5.

Fracture nonunion in long bones: A literature review of risk factors and surgical management

Nonunion following a long bone fracture causes considerable morbidity when it occurs. Risk factors depend on specific fractures but there is a complex interplay of injury severity, comorbidities, patient medication and infection. The majority of nonunions occur after long bone fractures with the tibia, femur, forearm, humerus and clavicle predominating. Despite interest in the biological augmentation of fracture healing, the majority of nonunions can be effectively managed with conventional surgical techniques. In this review we present a review of risk factors for nonunion and the outcome following surgical management.

Pediatric aseptic lower leg fracture nonunion

PURPOSE

Lower leg nonunion in pediatric patients is a rarity. Therefore, eight European pediatric trauma units retrospectively analyzed all patients younger than 18 years suffering lower leg fractures resulting in aseptic nonunion.

METHODS

Thirteen children and adolescents less than 18 years old (2 girls and 11 boys) diagnosed with aseptic nonunion of the tibia and/or fibula were evaluated. In all patients, epidemiological data, mechanism of injury, fracture configuration, and the initial treatment concept were assessed, and the entire medical case documentation was observed. Furthermore, potential causes of nonunion development were evaluated.

RESULTS

The mean age of patients was 12.3 years with the youngest patient being seven and the oldest being 17 years old. Open fractures were found in six out of thirteen patients (46%). Nonunion was hypertrophic in ten and oligotrophic in three patients. Mean range of time to nonunion occurrence was 7.3 ± 4.6 months. Nonunion healing resulting in complete metal removal was found in 12 out of 13 patients (92%), only in one case of a misinterpreted CPT type II osseous consolidation could not be found during the observation period. Mean range of time between surgical nonunion revision and osseous healing was 7.3 months as well.

CONCLUSION

If treatment principles of the growing skeleton are followed consistently, aseptic nonunion of the lower leg remains a rare complication in children and adolescents. Factors influencing the risk of fracture nonunion development include patient's age, extended soft tissue damage, relevant bone loss, and inadequate initial treatment.

Double plating with autogenous bone grafting as a salvage procedure for recalcitrant humeral shaft nonunion

Background

Although most cases of humeral shaft nonunion respond well to surgical intervention, surgeons still encounter patients with humeral shaft nonunion who have already undergone repeated surgeries for nonunion. This study retrospectively analyzed the efficacy of double locking compression plate (LCP) fixation in combination with autogenous iliac crest bone grafting for recalcitrant humeral shaft nonunion.

Methods

A consecutive series of patients with aseptic recalcitrant humeral shaft nonunion underwent surgical treatment between May 2010 and August 2017 in our institution. Standardized treatment included thorough debridement, double LCP and screw fixation, and autogenous iliac bone grafting. The injury type and the duration of nonunion were recorded for all patients. The main outcome measurements were the Constant and Murley scale for shoulder function, Mayo elbow performance index (MEPI) for elbow function, and visual analog scale (VAS) for pain. In addition, all complications were documented.

Results

The study cohort comprised six females and nine males with a mean age of 45.3 ± 13.1 years. Each patient had already undergone at least one failed surgery for humeral shaft nonunion. The average duration of nonunion before the index intervention was 126.8 ± 124.2 months. All patients achieved bone union without implant failure. At final follow-up, the mean Constant and Murley score and mean MEPI were significantly improved, and the mean VAS score was significantly decreased. Each patient was very satisfied with the treatment. Four patients had complications, including one with a superficial wound infection, one with radial nerve palsy, one with ulnar nerve palsy, and one with discomfort at the iliac crest.

Conclusion

Double plate fixation combined with autogenous iliac crest bone grafting results in successful salvage of humeral shaft nonunion after prior failed surgical interventions.

Synergistic use of biomaterials and licensed therapeutics to manipulate bone remodelling and promote non-union fracture repair

Disrupted bone metabolism can lead to delayed fracture healing or non-union, often requiring intervention to correct. Although the current clinical gold standard bone graft implants and commercial bone graft substitutes are effective, they possess inherent drawbacks and are limited in their therapeutic capacity for delayed union and non-union repair. Research into advanced biomaterials and therapeutic biomolecules has shown great potential for driving bone regeneration, although few have achieved commercial success or clinical translation. There are a number of therapeutics, which influence bone remodelling, currently licensed for clinical use. Providing an alternative local delivery context for these therapies, can enhance their efficacy and is an emerging trend in bone regenerative therapeutic strategies. This review aims to provide an overview of how biomaterial design has advanced from currently available commercial bone graft substitutes to accommodate previously licensed therapeutics that target local bone restoration and healing in a synergistic manner, and the challenges faced in progressing this research towards clinical reality.

Prevalence and influencing factors of nonunion in patients with tibial fracture: systematic review and meta-analysis

OBJECTIVE

The aim of this study is to assess the prevalence of nonunion in patients with tibia fracture and the association between influencing factors and tibia fracture nonunion.

METHOD

A database searches of PubMed, the Cochrane Library, EMBASE, China National Knowledge Infrastructure (CNKI), Weipu database, and Wanfang database from inception until June 2019 was conducted. The pooled prevalence, odds ratio (OR), and 95% confidence intervals (CI) were calculated with Stata software.

RESULTS

In this study, 111 studies involving 41,429 subjects were included. In the study of the relationship between influencing factors and tibia fracture nonunion, 15 factors significantly influenced the fracture union, including > 60 years old, male, tobacco smoker, body mass index > 40, diabetes, nonsteroidal anti-inflammatory drugs (NSAIDs) user, opioids user, fracture of middle and distal tibia, high-energy fracture, open fracture, Gustilo-Anderson grade IIIB or IIIC, Müller AO Classification of Fractures C, open reduction, fixation model, and infection.

CONCLUSION

The prevalence of nonunion in patients with tibia fracture was 0.068 and 15 potential factors were associated with the prevalence. Closed reduction and minimally invasive percutaneous plate osteosynthesis (MIPPO) have the low risks of nonunion for the treatment of tibial fractures.

The Life of a Fracture: Biologic Progression, Healing Gone Awry, and Evaluation of Union

New knowledge about the molecular biology of fracture-healing provides opportunities for intervention and reduction of risk for specific phases that are affected by disease and medications. Modifiable and nonmodifiable risk factors can prolong healing, and the informed clinician should optimize each patient to provide the best chance for union. Techniques to monitor progression of fracture-healing have not changed substantially over time; new objective modalities are needed.

Risk of Nonunion with Nonselective NSAIDs, COX-2 Inhibitors, and Opioids

BACKGROUND

Cyclooxygenase-2 (COX-2) has been found to be important for fracture-healing in animal models, raising concerns about use of nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors after fractures. We evaluated associations of NSAIDs, COX-2 inhibitors, and opioids with nonunion after long-bone fracture.

METHODS

Using private health insurance claims data from Optum's de-identified Clinformatics Data Mart database from January 1, 2000, to September 30, 2015, we identified adults with a single long-bone fracture or commonly paired long-bone fractures who had 1 year of available follow-up data. Using multivariable logistic regression models, we examined associations between NSAID, COX-2-inhibitor, or opioid prescription fills after the fracture and the risk of nonunion within 1 year, defined as a nonunion diagnosis with a procedure to treat the nonunion.

RESULTS

A nonunion diagnosis with a procedure to treat the nonunion was identified after 2,996 (0.9%) of the 339,864 fracture episodes, with rates varying by fracture site. The risk of that outcome was greater in patients who had filled COX-2-inhibitor prescriptions (adjusted odds ratio = 1.84 [95% confidence interval = 1.38 to 2.46]) or opioid prescriptions (1.69 [1.53 to 1.86]), but not in patients who had filled nonselective-NSAID prescriptions (1.07 [0.93 to 1.23]) after the fracture. Results were similar when the outcome definition was changed to just a nonunion diagnosis.

CONCLUSIONS

COX-2 inhibitors, but not nonselective NSAIDs, were associated with a greater risk of nonunion after fracture. Opioids were also associated with nonunion risk, although patients filling prescriptions for opioids may have had more severe fractures.

LEVEL OF EVIDENCE

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