Titanium versus stainless steel alloy bridge plates for distal femur fractures: Does callus form earlier with titanium?

INTRODUCTION: Distal femur fractures account for 3-6% of all femur fractures. Internal fixation of most distal femur fractures with an anatomic lateral locking plate should permit some motion at the metaphyseal portion of the fracture when secondary bone healing is planned by the operating surgeon. While several studies have been performed evaluating union rates for distal femur fractures with stainless steel and titanium plates, the timing of callus formation between stainless steel and titanium implants used as bridge plates for distal femur fractures (AO/OTA 33-A and -C) has been investigated to a lesser extent. We hypothesize that callus will be visualized earlier with post-operative radiographs with titanium versus stainless steel bridge plates. METHODS: We retrospectively reviewed a consecutive cohort of patients over 18 years of age with acute AO/OTA 33-A and 33-C fracture patterns treated with an isolated stainless steel or titanium lateral bridge plate within 4 weeks of injury by a single fellowship-trained orthopedic trauma surgeon from 2011 to 2020 at one academic Level 1 trauma center. An independent, fellowship-trained orthopedic trauma attending surgeon reviewed anterior-posterior (AP) and lateral radiographs from every available post-operative clinic visit and graded them using the Modified Radiographic Score for Tibia (mRUST). RESULTS: Twenty-five subjects were included in the study with 10 with stainless steel and 15 with titanium plates. There were no significant differences in demographics between both groups, including age, sex, BMI, injury classification, open versus closed, mechanism, and laterality. Statistically significant increased mRUST scores, indicating increased callus formation, were seen on 12-week radiographs (8.4 vs. 11.9, p = 0.02) when titanium bridge plates were used. There were no statistically significant differences in mRUST scores at 6 or 24-weeks, but scores in the titanium group were higher in at every timepoint. DISCUSSION: In conclusion, we observed greater callus formation at 12 weeks after internal fixation of 33-A and 33-C distal femur fractures treated with titanium locked lateral distal femoral bridge plates compared to stainless steel plates. Our data suggest that titanium metallurgy may have quicker callus formation compared to stainless steel if an isolated, lateral locked bridge plate is chosen for distal femur fracture fixation.

Early Reciprocal Effects in a Murine Model of Traumatic Brain Injury and Femoral Fracture.

Traumatic brain injury (TBI) represents a major cause of death and disability in early adulthood. Concomitant extracranial injury such as long bone fracture was reported to exacerbate TBI pathology. However, early reciprocal effects and mechanisms have been barely investigated. To address this issue, C57BL/6N mice were subjected to either the controlled cortical impact (CCI) model of TBI, fracture of the left femur (FF), combined injury (CCI+FF), or sham procedure. Behavioral alterations were monitored until 5 days post injury (dpi), followed by (immuno-)histology, gene and protein expression analyses using quantitative PCR, western blot, and ELISA. We found that CCI+FF mice exhibited increased neurological impairments, reduced recovery, and altered anxiety-related behavior compared to single injury groups. At 5 dpi, cerebral lesion size was not affected by combined injury but exaggerated hippocampal substance loss and increased perilesional astrogliosis were observed in CCI+FF mice compared to isolated CCI. Bone gene expression of the osteogenic markers Runx2, osteocalcin, alkaline phosphatase, and bone sialoprotein was induced by fracture injury but attenuated by concomitant TBI. Plasma concentrations of the biomarkers osteopontin and progranulin were elevated in CCI+FF mice compared to other experimental groups. Taken together, using a murine model of TBI and femoral fracture, we report early reciprocal impairments of brain tissue maintenance, behavioral recovery, and bone repair gene expression. Increased circulating levels of the biomarkers osteopontin and progranulin indicate ongoing tissue inflammation and repair. Our results may have implications for future therapeutic approaches to interfere with the pathological crosstalk between TBI and concomitant bone fracture.

Removal of cement-augmented screws in distal femoral fractures and the effect of retained screws and cement on total knee arthroplasty: a biomechanical investigation.

BACKGROUND: Given the increasing number of osteoporotic fractures of the distal femur, screw augmentation with bone cement is an option to enhance implant anchorage. However, in implant removal or revision surgeries, the cement cannot be removed from the distal femur without an extended surgical procedure. Therefore, the aims of this study were to investigate (1) whether cement augmentation has any influence on screw removal and removal torque, and (2) whether the implantation of a femoral component of a knee arthroplasty and its initial interface stability are affected by the remaining screws/cement. MATERIAL AND METHODS: Eight pairs of fresh-frozen human female cadaveric distal femurs (mean age, 86 years) with a simulated AO/OTA 33 A3 fracture were randomized in paired fashion to two groups and fixed with a distal femoral locking plate using cannulated perforated locking screws. Screw augmentation with bone cement was performed in one of the groups, while the other group received no screw augmentation. Following biomechanical testing until failure (results published separately), the screws were removed and the removal torque was measured. A femoral component of a knee arthroplasty was then implanted, and pull-out tests were performed after cement curing. Interference from broken screws/cement was assessed, and the maximum pull-out force was measured. RESULTS: The mean screw removal torque was not significantly different between the augmented (4.9 Nm, SD 0.9) and nonaugmented (4.6 Nm, SD 1.3, p = 0.65) screw groups. However, there were significantly more broken screws in in the augmented screw group (17 versus 9; p < 0.001). There was no significant difference in the pull-out force of the femoral component between the augmented (2625 N, SD 603) and nonaugmented (2653 N, SD 542, p = 0.94) screw groups. CONCLUSION: The screw removal torque during implant removal surgery does not significantly differ between augmented and nonaugmented screws. In the augmented screw group, significantly more screws failed. To overcome this, the use of solid screws in holes B, C, and G can be considered. Additionally, it is possible to implant a femoral component for knee arthroplasty that retains the initial anchorage and does not suffer from interference with broken screws and/or residual cement. LEVEL OF EVIDENCE: 5.

BDNF promoted osteoblast migration and fracture healing by up-regulating integrin ß1 via TrkB-mediated ERK1/2 and AKT signalling.

Brain-derived neurotrophic factor (BDNF) has been reported to participate in fracture healing, whereas the mechanism is still unclear. Since osteoblast migration is important for fracture healing, investigating effects of BDNF on osteoblasts migration may help to reveal its mechanism. Here, MC3T3-E1 cells were used in vitro while closed femur fracture mice were applied in vivo. Cells migration was assessed with Transwell assay. The protein expression was analysed by immunoblotting. X-ray and Micro-CT were performed at different time after fracture. Our results showed that BDNF promoted MC3T3-E1 cells migration, integrin ß1 expression and ERK1/2 and AKT phosphorylation. K252a, a specific inhibitor for TrkB, suppressed BDNF-induced migration, integrin ß1 expression and activation of ERK1/2 and AKT. PD98059 (an ERK1/2 inhibitor) and LY294002 (an AKT inhibitor) both inhibited BDNF-induced migration and integrin ß1 expression while integrin ß1 blocking antibody only suppressed cell migration. X-ray and Micro-CT analyses showed that the adenoviral carried integrin ß1 shRNA group had slower fracture healing at 7 and 21 days, but not 35 days compared to the control group. Thus, we proposed that BDNF stimulated MC3T3-E1 cells migration by up-regulating integrin ß1 via TrkB mediated ERK1/2 and AKT signalling, and this may help to enhance the fracture healing.

Extracorporeal shock wave therapy accelerates endochondral ossification and fracture healing in a rat femur delayed-union model.

Extracorporeal shock wave therapy (ESWT) has been demonstrated to accelerate bone healing; however, the mechanism underlying ESWT-induced bone regeneration has not been fully elucidated. This study aimed to examine the effects of ESWT and the process of fracture healing. A rat model of femur delayed-union was established by cauterizing the periosteum. ESWT treatment at the fracture site was performed 2 weeks after the operation and the site was radiographically and histologically evaluated at weeks 4, 6, and 8. The bone union rate and radiographic score of the ESWT group were significantly higher than those of the control group at 8 weeks. Histological evaluation revealed enhanced endochondral ossification at the fracture site. The effects of ESWT on ATDC5 cells were examined in vitro. ESWT promoted chondrogenic differentiation without inhibiting the proliferation of ATDC5 cells. ESWT may induce significant bone healing by promoting endochondral ossification at the fracture site.

Hypophosphatasia in Adults: Clinical Spectrum and Its Association With Genetics and Metabolic Substrates.

BACKGROUND: Hypophosphatasia (HPP) is a rare metabolic bone disorder caused by mutations in the alkaline phosphatase (ALPL) gene, and characterized by low circulating alkaline phosphatase (ALP) levels and bone, muscle, dental and systemic manifestations. In this case series we investigate the clinical spectrum, genetic and biochemical profile of adult HPP patients from the University Hospitals Leuven, Belgium. METHODOLOGY: Adults with HPP were identified through medical record review. Inclusion criteria were: (1) age ≥ 16 yr; (2) consecutively low ALP levels not explained by secondary causes; (3) one or more of the following supporting criteria: biochemical evidence of elevated enzyme substrates; subtrochanteric fractures, metatarsal fractures or other typical clinical features; family history of HPP; a known or likely pathogenic ALPL mutation. RESULTS: Nineteen patients met our inclusion criteria (n = 2 infantile, n = 6 childhood, n = 10 adult-onset HPP and one asymptomatic carrier). Fractures and dental abnormalities were the most reported symptoms. Fatigue was reported in n = 7/19 patients (37%), three of which had previously been misdiagnosed as having chronic fatigue syndrome and/or fibromyalgia. Empirical pyridoxine therapy in four patients (without seizures) did not provide symptomatic relief. N = 7/19 patients (37%) were inappropriately treated or planned to be treated with antiresorptive treatment. Two patients developed atypical femoral fractures following exposure to bisphosphonates and/or denosumab. Patients detected by screening were less severely affected, while patients with homozygous or compound heterozygous mutations had the most severe symptoms, significantly lower circulating ALP levels (p = 0.013) and significantly higher pyridoxal-5'-phosphate (p = 0.0018) and urinary phosphoethanolamine (p = 0.0001) concentrations. CONCLUSIONS: Screening may detect mainly less severely affected individuals, which may nevertheless avoid misdiagnosis and inappropriate antiresorptive drug exposure. Patients with biallelic mutations had more severe symptoms, significantly lower ALP and higher substrate levels. Whether the latter finding has implications for the classification and treatment of HPP should be investigated further in larger cohorts.

Does the induced membrane have antibacterial properties? An experimental rat model of a chronic infected nonunion.

INTRODUCTION: The Masquelet procedure proved its efficiency in treating infected nonunion filling bony gaps up to 25 cm. Yet the use of local antibiotics is still questionable in the daily practice with lack of evidence regarding its usefulness in controlling infection. An experimental rat model is put in place to study the antibacterial properties of the induced membrane produced during the first stage of Masquelet. METHOD: Twenty-three-month-old wistar male rats are inoculated with a 0.5 mL solution of 10^8 CFU/mL MRSA over a critical fracture done on the right femur. Six weeks later, remaining 11 rats exhibiting signs of a chronic infection with a sinus tract and oozing pus along with radiological nonunion are used for a first stage Masquelet procedure. They are randomly divided into two groups with six rats having no local antibiotic in the cement mixture and five rats having 3 g of vancomycin mixed with gentamycin loaded cement. Six weeks later (twelve weeks from baseline), all eleven rats are euthanized and blood samples for C-reactive protein are withdrawn. The induced membrane is identified and resected along with bone fragments and sent for cultures and pathology. RESULTS: MRSA is isolated in the cultures of all six rats in the first group where no local antibiotic was added. Altered polymorphonuclears with abscess and pus are noted on four of six pathology samples. However in the second group where local antibiotics were added, three out of five rats exhibited eradication of MRSA (p = 0.034) and all samples did not exhibit clear infection signs on pathology. A pyo-epithelioid over a foreign body reaction is seen predominantly in this group demonstrating a regenerative process. DISCUSSION: The induced membrane does not have antimicrobial properties capable of overcoming an infected nonunion on its own. When local antibiotics were added during the first stage of the Masquelet procedure, new bone formation occurred indicating the need to control an infection in order for bone union to occur. CONCLUSION: Local antibiotics use in adjunction to extensive debridement is advisable during the first stage of a Masquelet procedure for an infected nonunion.

Establishment of a clinically relevant large animal model to assess the healing of metaphyseal bone.

Despite the high incidence of metaphyseal bone fractures in patients, the mechanisms underlying the healing processes are poorly understood due to the lack of suitable experimental animal models. Hence, the present study was conducted to establish and characterise a clinically relevant large-animal model for metaphyseal bone healing. Six female adult Merino sheep underwent full wedge-shaped osteotomy at the distal left femur metaphysis. The osteotomy was stabilised internally with a customised anatomical locking titanium plate that allowed immediate post-operative full-weight bearing. Bone healing was evaluated at 12 weeks post-fracture relative to the untouched right femur. Histological and quantitative micro-computed tomography results revealed an increased mineralised bone mass with a rich bone microarchitecture. New trabeculae healed by direct intramembranous ossification, without callus and cartilaginous tissue formation. Stiffness at the cortical and trabecular regions was comparable in both groups. Functional morphological analysis of the osteocyte lacunae revealed regularly arranged spherically shaped lacunae along with the canalicular network. Bone surface biochemical analysis using time-of-flight secondary-ion mass spectrometry showed high and homogeneously distributed levels of calcium and collagenous components. Ultrastructure imaging of the new trabeculae revealed a characteristic parallel arrangement of the collagen fibrils, evenly mineralised by the dense mineral substance. The specialised bone cells were also characterised by their unique structural features. Bone remodelling in the fractured femur was evident in the higher expression levels of prominent bone formation and resorption genes. In conclusion, the novel metaphyseal fracture model is beneficial for studying healing and treatment options for the enhancement of metaphyseal bone defects.

Optimal administration frequency and dose of teriparatide for acceleration of biomechanical healing of long-bone fracture in a mouse model.

Despite preclinical studies demonstrating the effectiveness of teriparatide for skeletal repair in small animals, inconclusive data from clinical trials have raised questions regarding the optimal teriparatide dosing regimen for bone repair. To address this, we assessed the effect of teriparatide frequency and dose on long-bone healing using a mouse femur osteotomy/fracture model. Eight-week-old male ICR mice were subjected to open femur osteotomies, then randomized into following five groups (n = 8 per group): vehicle; low dose/high frequency: 3 µg/kg/dose, 3 times/day; low dose/low frequency: 9 µg/kg/dose, 1 time/day; high dose/high frequency: 9 µg/kg/dose, 3 times/day; high dose/low frequency: 27 µg/kg/dose, 1 time/day. Skeletal repair was assessed by microcomputed tomography, mechanical testing, and histology 4 weeks after surgery. High-dose and/or high-frequency teriparatide treatment increased callus bone volume but failed to have a significant impact on the biomechanical recovery of fractured femurs, possibly because of impaired cortical shell formation in fracture calluses. Meanwhile, low-dose/low-frequency teriparatide therapy enhanced callus bone formation without interfering with cortical shell formation despite a lesser increase in callus bone volume, leading to significant two and fourfold increases in ultimate load and stiffness, respectively. Our findings demonstrate that administering teriparatide at higher doses and/or higher frequencies raises fracture callus volume but does not always accelerate the biomechanical recovery of fractured bone, which points to the importance of finding the optimal teriparatide dosing regimen for accelerating skeletal repair.

The Role of Lower-Limb Geometry in the Pathophysiology of Atypical Femoral Fracture.

PURPOSEOF REVIEW: The etiology of atypical femoral fracture (AFF) is likely multifactorial. In this review, we examined the recent literature investigating the role of lower-limb geometry in the pathophysiology of AFF. RECENT FINDINGS: Increased femoral bowing was associated with prevalent AFF and a greater likelihood of a diaphyseal versus a subtrochanteric AFF location. Femoral neck geometry or hip alignment may also be related to AFF, but findings remain equivocal. Differences in femoral geometry may, in part, be responsible for the high rate of AFF in Asian compared with Caucasian populations. Finally, simulation studies suggest that lower-limb geometry influences AFF risk via its effects on mechanical strain of the lateral femoral cortex. Femoral geometry, and bowing in particular, is related to prevalent AFF, but more prospective investigation is needed to determine whether measurements of geometry can be used for clinical risk stratification.

Different effects of Wnt/ß-catenin activation and parathyroid hormone on diaphyseal and metaphyseal in the early phase of femur bone healing of mice.

Parathyroid hormone (PTH) and agents related to the manipulation of Wnt/ß-catenin signalling are two promising anabolic anti-osteoporotic therapies that have been shown to promote the healing of bone fractures. Now, it is widely accepted that cortical bone and trabecular bone are two different compartments, and should be treated as separate compartments in pathological processes, such as fracture healing. It is currently unknown whether PTH and the activation of ß-catenin signalling would demonstrate different effects on cortical bone and trabecular bone healing. In the current study, single 0.6-mm cortex holes were made in the femur metaphysis and diaphysis of mice, and then, PTH application and ß-catenin activation were used to observe the promoting effect on bone healing. The effects of ß-catenin and PTH signalling on fracture healing were observed by X-ray and CT at 3, 6, and 14 days after fracture, and the levels of ß-catenin were detected by RT-PCR assay, and the number of specific antigen-positive cells of BRDU, OCN, RUNX2 was counted by immunohistochemical staining. While ß-catenin activation and PTH were found to demonstrate similar effects on accelerating metaphyseal bone healing, activation of ß-catenin showed a more striking effect than PTH on promoting diaphyseal bone healing. These findings might be helpful for selecting proper medication to accelerate fracture healing of different bone compartments.

Vascularized Periosteal Flaps Accelerate Osteointegration and Revascularization of Allografts in Rats.

BACKGROUND: Surgical reconstruction of large bone defects with structural bone allografts can restore bone stock but is associated with complications such as nonunion, fracture, and infection. Vascularized reconstructive techniques may provide an alternative in the repair of critical bone defects; however, no studies specifically addressing the role of vascularized periosteal flaps in stimulating bone allograft revascularization and osseointegration have been reported. QUESTIONS/PURPOSES: (1) Does a vascularized periosteal flap increase the likelihood of union at the allograft-host junction in a critical-size defect femoral model in rats? (2) Does a vascularized periosteal flap promote revascularization of a critical-size defect structural bone allograft in a rat model? (3) What type of ossification occurs in connection with a vascularized periosteal flap? METHODS: Sixty-four rats were assigned to two equal groups. In both the control and experimental groups, a 5-cm critical size femoral defect was created in the left femur and then reconstructed with a cryopreserved structural bone allograft and intramedullary nail. In the experimental group, a vascularized periosteal flap from the medial femoral condyle, with a pedicle based on the descending genicular vessels, was associated with the allograft. The 32 rats of each group were divided into subgroups of 4-week (eight rats), 6-week (eight rats), and 10-week (16 rats) followup. At the end of their assigned followup periods, the animals were euthanized and their femurs were harvested for semiquantitative and quantitative analysis using micro-CT (all followup groups), quantitative biomechanical evaluation (eight rats from each 10-week followup group), qualitative confocal microscopic, backscattered electron microscopic, and histology analysis (4-week and 6-week groups and eight rats from each 10-week followup group). When making their analyses, all the examiners were blinded to the treatment groups from which the samples came. RESULTS: There was an improvement in allograft-host bone union in the 10-week experimental group (odds ratio [OR], 19.29 [3.63-184.50], p < 0.05). In contrast to control specimens, greater bone neoformation in the allograft segment was observed in the experimental group (OR [4-week] 63.3 [39.6-87.0], p < 0.05; OR [6-week] 43.4 [20.5-66.3], p < 0.05; OR [10-week] 62.9 [40.1-85.7], p < 0.05). In our biomechanical testing, control samples were not evaluable as a result of premature breakage during the embedding and assembly processes. Therefore, experimental samples were compared with untreated contralateral femurs. No difference in torsion resistance pattern was observed between both groups. Both backscattered electron microscopy and histology showed newly formed bone tissue and osteoclast lacunae, indicating a regulated process of bone regeneration of the initial allograft in evaluated samples from the experimental group. They also showed intramembranous ossification produced by the vascularized periosteal flap in evaluated samples from the experimental group, whereas samples from the control group showed an attempted endochondral ossification in the allograft-host bone junctions. CONCLUSIONS: A vascularized periosteal flap promotes and accelerates allograft-host bone union and revascularization of cryopreserved structural bone allografts through intramembranous ossification in a preclinical rat model. CLINICAL RELEVANCE: If large-animal models substantiate the findings made here, this approach might be used in allograft reconstructions for critical defects using fibular or tibial periosteal flaps as previously described.

The influence of ageing on the incidence and site of trauma femoral fractures: a cross-sectional analysis.

BACKGROUND: This study aimed to determine the influence of ageing on the incidence and site of femoral fractures in trauma patients, by taking the sex, body weight, and trauma mechanisms into account. METHODS: This retrospective study reviewed data from adult trauma patients aged ≥20 years who were admitted into a Level I trauma center, between January 1, 2009 and December 31, 2016. According to the femoral fracture locations, 3859 adult patients with 4011 fracture sites were grouped into five subgroups: proximal type A (n = 1359), proximal type B (n = 1487), proximal type C (n = 59), femoral shaft (n = 640), and distal femur (n = 466) groups. A multivariate logistic regression analysis was applied to identify independent effects of the univariate predictive variables on the occurrence of fracture at a specific site. A two-dimensional plot was presented visually with age and the propensity score accounts for the risk of a fracture at a specific femoral site. RESULTS: This analysis revealed that older age was an independent variable that could positively predict the occurrence of proximal type A (OR [95%CI]: 1.03 [1.03-1.04], p < 0.001) and B fractures (1.02 [1.01-1.02], p < 0.001), and negatively predict the occurrence of proximal type C (0.96 [0.94-0.98], p < 0.001), shaft (0.95 [0.95-0.96], p < 0.001), and distal fractures (0.98 [0.98-0.99], p < 0.001). DISCUSSION: Using the propensity scores which account for the risk of a fracture in a specific femoral site, this study revealed that the older patients were at a higher risk of developing proximal type A and type B fractures, while a lower risk of developing fractures in the shaft and distal femur. This incidence of fracture site can largely be explained by age-related factors, including a decrease in bone strength and falling being the most common mechanism of trauma in older patients. CONCLUSIONS: This study revealed a difference in the involvement of age in the incidence of femoral fracture sites in the trauma patients.

Anatomy-based MRI assessment of the iliopsoas muscle complex after pertrochanteric femoral fracture.

OBJECTIVE: To evaluate the quality of the iliopsoas muscle complex after pertrochanteric femoral fracture, using MRI; to propose an anatomy-based evaluation of the iliopsoas muscle complex; and to determine the inter-reader reliability of two classifications of fatty muscle degeneration. MATERIALS AND METHODS: We included adult patients with a displaced lesser trochanter following pertrochanteric femoral fracture. Muscle quality was evaluated using the Goutallier and Slabaugh classifications at three levels (L4/L5, L5/S1, and the anterior inferior iliac spine). Two radiologists independently reviewed the MRIs, and force measurement was performed on both hips. Linear mixed-effects models were used to determine the effect of fracture on muscle quality and strength, and Cohen's kappa statistic was used to assess inter-reader agreement. RESULTS: In the 18 patients included, the iliopsoas muscle complex showed higher grades of fatty muscle degeneration on the fractured side than on the non-fractured side. The mean difference between muscle strength on the fractured vs the non-fractured side was -12 N (p > 0.05). Inter-reader agreement for the Goutallier and Slabaugh classifications was good and very good respectively (weighted K = 0.78 and 0.85 respectively). CONCLUSION: Fatty muscle degeneration of the iliopsoas muscle complex after pertrochanteric femoral fracture was evident using both classification systems; however, fatty muscle degeneration resulted in only a minimal reduction of muscle strength. To provide a thorough assessment of iliopsoas muscle complex quality, we suggest evaluating it at different anatomical levels. Regarding inter-reader agreement, the Slabaugh classification was superior to the Goutallier classification.

Towards a Non-Invasive Technique for Healing Assessment of Internally Fixated Femur.

The lack of a quantitative method to adequately assess fractured bone healing that has undergone fixation limits prognostic capabilities on patients' optimal return to work. This paper addresses the use of vibrational analysis to monitor the state of healing of a plate-screw fixated femur and supplement the current clinical radiographic assessment. This experimental study involves an osteotomised composite femur specimen enclosed by modelling clay to simulate the damping effect of overlying soft tissues. Epoxy adhesives are applied to the fractured region and to simulate the healing process. With the instrumentation described, the cross-spectrum and coherence are obtained and analysed in the frequency domain over a period of time. The results suggest that it is crucial to analyse the cross-spectrum and proposed healing index to quantitatively assess the stages of healing. The results also show that the mass loading effect due to modelling clay did not influence the proposed healing assessment technique. The findings indicate a potential non-intrusive technique to evaluate the healing of fractured femur by utilising the vibrational responses.

The impact of the third fragment features on the healing of femoral shaft fractures managed with intramedullary nailing: a radiological study.

INTRODUCTION: Femoral shaft fractures with third fragments have a high non-union rate, which may reach 14%. This study aims to assess the impact of the radiological features of the third fragment, evaluated on post-operative X-rays, on the outcome of femoral shaft fractures type 32-B managed with intramedullary nailing, in order to obtain an algorithm which could predict the fracture healing time. MATERIALS AND METHODS: We have retrospectively evaluated a series of 52 patients. On post-operative X-rays, four radiological parameters were evaluated: the third fragment angle, the fracture gap, the third fragment size, and the mean third fragment displacement. All the patients underwent a radiologic follow-up at one, two, three, six, nine and 12 months post-operatively, to assess the bone healing. The patients were then divided into three groups, according to the fracture healing time: within six months (group A), between six and 12 months (group B), or fracture non-union after 12 months (group C). RESULTS: In 28 patients, out of 52 (53.85%), the fracture healing was observed at 6-month follow-up; in 18 patients, out of 52 (34.62%), the fracture healed within 12 months after trauma; and in six patients, out of 52 (11.54%), no fracture healing was observed at 12-month follow-up. The mean third fragment size was significantly different in each group (p < 0.05), while the mean third fragment displacement was significantly higher in group C, compared with group A (p = 0.0006) and group B (p = 0.0027). In group B, a positive correlation was found between the fracture healing time and the mean third fragment size (R = 0.594, p = 0.036); in group C, the fracture union time was positively related to the third fragment size (R = 0.689, p = 0.013) and the mean third fragment displacement (R = 0.7107, p = 0.006). Regression analysis showed that the third fragment size and the mean third fragment displacement are the most important features which affect the fracture healing time. CONCLUSIONS: The third fragment size (cutoff 40 mm) is the leading parameter to influence the fracture healing within or in more than six months. The mean third fragment displacement (cutoff 12 mm); on the other hand, impacts on the fracture delayed rather than absent healing.

Development of a novel murine delayed secondary fracture healing in vivo model using periosteal cauterization.

INTRODUCTION: Delayed union and nonunion development remain a major clinical problematic complication during fracture healing, with partially unclear pathophysiology. Incidences range from 5 to 40% in high-risk patients, such as patients with periosteal damage. The periosteum is essential in adequate fracture healing, especially during soft callus formation. In this study, we hypothesize that inducing periosteal damage in a murine bone healing model will result in a novel delayed union model. MATERIALS AND METHODS: A mid-shaft femoral non-critically sized osteotomy was created in skeletally mature C57BL/6 mice and stabilized with a bridging plate. In half of the mice, a thin band of periosteum adjacent to the osteotomy was cauterized. Over 42 days of healing, radiographic, biomechanical, micro-computed tomography and histological analysis was performed to assess the degree of fracture healing. RESULTS: Analysis showed complete secondary fracture healing in the control group without periosteal injury. Whereas the periosteal injury group demonstrated less than half as much maximum callus volume (p < 0.05) and bridging, recovery of stiffness and temporal expression of callus growth and remodelling was delayed by 7-15 days. CONCLUSION: This paper introduces a novel mouse model of delayed union without a critically sized defect and with standardized biomechanical conditions, which enables further investigation into the molecular biological, biomechanical, and biochemical processes involved in (delayed) fracture healing and nonunion development. This model provides a continuum between normal fracture healing and the development of nonunions.

Cementing of the hip arthroplasty stem increases load-to-failure force: a cadaveric study.

Background and purpose - To date, there is not a single clinical or mechanical study directly comparing a cemented and a cementless version of the same stem. We investigated the load-to-failure force of a cementless and a cemented version of a double tapered stem. Material and methods - 10 femurs from 5 human cadaveric specimens, mean age 74 years (68-79) were extracted. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography. None of the specimens had a compromised quality (average T value 0.0, -1.0 to 1.4). Each specimen from a pair randomly received a cemented or a cementless version of the same stem. A material testing machine was used for lateral load-to-failure test of up to a maximal load of 5.0 kN. Results - Average load-to-failure of the cemented stem was 2.8 kN (2.3-3.2) and 2.2 kN (1.8-2.8) for the cementless stem (p = 0.002). The cemented version of the stem sustained a higher load than its cementless counterpart in all cases. Failure force was not statistically significantly correlated to BMD (p = 0.07). Interpretation - Implanting a cemented version of the stem increases the load-to-failure force by 25%.

Paediatric conjoint bicondylar Hoffa fracture with patellar tendon injury: An unusual pattern of injury.

Epiphyseal injuries of distal femur are rare with an incidence of 1%-6% among all physeal injuries. Prompt diagnosis and appropriate surgical treatment is crucial to achieve satisfactory functional outcomes. A conjoint bicondylar coronal split (Hoffa) fracture with complete transaction of ipsilateral patellar tendon has been reported in a 12 year old child. The injury was managed by open reduction and internal fixation and bone to tendon repair. This case emphasizes the need of accurate intraepiphyseal fixation for the management of these fractures in skeletally immature patients.

Biomechanical comparison of fracture site stabilities of femur nails after fracture site resorption.

Instability increases after fracture site resorption. This study aimed to compare the fracture site stabilities of different femoral nails after fracture site resorption. Thirty composite femurs were divided into three groups of 10 interlocking nails. Using axial compression-distraction machines and a custom-made torsion device, the fracture site rotational and axial stabilities after 1 mm fracture site resorption were determined. Between 6 Nm external and 6 Nm internal rotation torques, the means of the maximum fracture site rotation arc of motion were 5.94 mm for compression nails, 5.9 mm for interlocking nails and 3.5 mm for CAROT nails. Between 2300 N compression and 150 N distraction forces, the means of the fracture site axial motion were 3.15 mm for interlocking nails, 1.26 mm for compression nails and 1.26 mm for CAROT nails. CAROT nails are superior to compression and interlocking nails in fracture site rotational and axial stabilities after 1 mm fracture site resorption.