Minimally invasive plate osteosynthesis for complex comminuted bone fractures in the Fraser's type II floating knee: a case report.

OBJECTIVE: Floating knee type IIC, according to Fraser's classification, is an uncommon severe injury that typically occurs in polytrauma. In such cases, intra-articular fracture and the high degree of comminution and deformity of the mid-distal femur make fixation challenging. The purpose of this study was to demonstrate that minimally invasive plate osteosynthesis (MIPO) technology can simplify these complex problems and improve patient prognosis. CASE PRESENTATION: A 38-year-old man injured his left leg in a car accident, causing pain, swelling, deformity, and limited mobility on his left knee and thigh, and two small open wounds were noted mainly of the anterior aspect of the mid-distal thigh. Physical examination and computed tomography angiography of the lower limb confirmed that there was no damage to the neurovascular system. The clinical diagnosis was closed intra-articular fracture of the proximal tibia, open intra-articular fracture of the distal femur with extension to the diaphysis, and a patellar fracture on the ipsilateral knee. The treatment strategy involved a locking plate system applying MIPO technology. Postoperative evaluation of the patient was satisfactory, with immediate functional exercise, full weight-bearing after three months, and return to daily activity without pain. Final follow-up taken 3 years after surgery showed good lower limb alignment and complete plasticity of the bone structure, by which time the patient showed good limb function. CONCLUSIONS: Minimally invasive techniques can provide a simple and effective treatment for some complex fractures.

Long noncoding RNA XIST modulates microRNA-135/CREB1 axis to influence osteogenic differentiation of osteoblast-like cells in mice with tibial fracture healing.

Fracture healing is a complex event with the involvement of many cell systems, cytokines, as well as mRNAs. Herein, we report the interactions among long noncoding RNA X-inactive specific transcript (XIST)/microRNA-135 (miR-135)/cAMP response element-binding protein 1 (CREB1) axis during fracture healing. We observed increased expression of XIST in patients with long-term unhealed fracture by microarray analysis. Subsequently, a mouse model with tibial fracture and a cell model using osteoblast-like MC3T3-E1 cells were generated. The XIST overexpression during fracture healing decreased proliferation and differentiation of MC3T3-E1 cells, while silencing of XIST facilitated MC3T3-E1 cell growth. Furthermore, miR-135 targeted CREB1 and negatively regulated its expression. XIST acted as a sponge for miR-135, thereby upregulating CREB1 and promoting the activity of the TNF-α/RANKL pathway. Transfection of miR-135 inhibitor or CREB1 overexpression blocked the stimulating effects of XIST knockdown on MC3T3-E1 cell growth. Besides, specific inhibitors of the TNF-α/RANKL pathway reversed the repressive role of XIST in cell osteogenic differentiation. All in all, these findings suggest that XIST knockdown induces the differentiation of osteoblast-like cells via regulation of the miR-135/CREB1/TNF-α/RANKL axis. XIST, as a consequence, represents an attractive therapeutic strategy to accelerate fracture healing.

Comparison of complications of early and delayed open reduction and internal fixation for treating pilon fracture: A protocol of systematic review and meta-analysis.

BACKGROUND: Tibial Pilon fractures are severe fractures accompanied by soft tissue injury. Although open reduction and internal fixation (ORIF) are effective in treating Pilon fractures, there is a controversy over time to surgery due to reported postoperative complications. However, there is no systematic review evaluating the difference of postoperative complications between early and delayed ORIF for treating pilon fractures. METHODS: Relevant literature written in English will be searched through PubMed, Cochrane Library, Embase, MEDLINE, and Web of Science. The study aims to compare the effects and complications of early and delayed ORIF for treating fresh pilon fractures in adult patients. The primary outcome will be infection rate, fracture union time, nonunion and malunion rate. And the secondary outcome will be metalwork removal, amputation, and ankle function grade. Two reviewers will independently assess the eligibility of the studies according to the pre-defined inclusion and exclusion criteria. A meta-analysis for the available data will be conducted using Revman 5.3. To measure effect size, odds ratios (ORs) and mean difference will be used for dichotomous and continuous data, respectively. Statistical heterogeneity will be explored. And a random-effects model or a fixed-effects will be used in pooled data on the basis of the existence or absence of heterogeneity. Subgroup analysis will be conducted to identify sources of heterogeneity and sensitivity analysis to test the results' robustness. We will assess the risk of bias by four different quality assessment tools according to the study design. Publication bias will be evaluated by funnel plot. The study data will be stored in the Open Science Framework website. PROSPERO REGISTRATION NUMBER: CRD42020207465.

Treatment of posterolateral tibial plateau fractures with a rotational support plate and special pressurizer: technical note and retrospective case series.

BACKGROUND: In tibial plateau fractures, the posterolateral segment of the tibia plateau is frequently affected and challenging to treat. Although there are many surgical approaches and fixation methods for the treatment of these fractures, all of these methods have limitations. We designed a new rotational support plate (RSP) and a special pressurizer that can fix the fracture directly via the anterolateral approach. This method is advantageous because it leads to little trauma, involves a simple operation, and has a reliable fixation effect. This study details the technique of treating these fractures with the RSP and special pressurizer and provides the outcomes. METHODS: From May 2016 to January 2019, the data of 12 patients with posterolateral tibial plateau fractures treated with the RSP and special pressurizer in our hospital were retrospectively analyzed. Postoperative rehabilitation was advised, knee X-rays were taken at follow-ups, and fracture healing, complications, and knee range of motion were assessed. The Hospital for Special Surgery (HSS) knee score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were used to evaluate knee function at the last follow-up. RESULTS: The average follow-up time of all patients was 16.5 months (range, 12-25 months). The average bony union time was 3.2 months (range, 3-4.5 months). At the last follow-up, the average knee range of motion was 138° (range, 107-145°). The average HSS score was 91 (range, 64-98). The average KOOS Symptoms score was 90 (range, 75-96). The average KOOS Pain score was 91 (range, 72-97). The average KOOS ADL score was 91 (range, 74-97). The average KOOS sport/recreation score was 83 (range, 70-90). The average KOOS QOL score was 88 (range, 69-93). Skin necrosis, incision infections, and fixation failure did not occur during the follow-up period. CONCLUSIONS: With our newly designed RSP and special pressurizer, posterolateral tibial plateau fractures can be easily and effectively reduced and fixed through the anterolateral approach, which serves as a novel treatment for posterolateral tibial plateau fractures.

The effect of aqueous extract of Prunus dulcis on tibial bone healing in the rabbit.

BACKGROUND: Bone fractures are medical emergencies that require prompt intervention to help return bone to its normal function. Various methods and treatments have been utilized to increase the speed and efficiency of bone repair. This study aimed to investigate the treatment effects of Prunus dulcis aqueous extract on tibial bone healing in rabbits. METHODS: All animals were distributed in five groups with six rats in each group, including the sham group, the control group in which tibial lesion was made and received distilled water, treatment groups with 150 mg kg-1, 300 mg kg-1 doses of Prunus dulcis extract, and osteocare treated group. Biochemical blood factors including calcium, phosphorus, and alkaline phosphatase (on days 0, 10, 30, and 50), biomarkers of oxidative stress such as GPx, CAT, and MDA (on days 10 and 30), radiological evaluation, histopathological parameters, and osteocalcin immunohistochemical expression were assessed. RESULTS: The data showed calcium levels in the treatment groups increased significantly from day 10 to day 50, respectively, and blood phosphorus levels decreased from day 10 to day 50 in the treatment groups. Alkaline phosphatase initially increased and then decreased in treatment groups. In the treatment groups, GPx and CAT levels significantly increased, and the serum amount of MDA reduced. The best antioxidant results were related to the extract-treated group with a higher dose. Radiographic score was significantly higher in the treatment groups than the control group on day 30. Based on the pathological findings, the healing occurred faster in the extract-treated group with a higher dose. Osteocalcin expression was significantly higher in the control group than that in the treatment groups. CONCLUSIONS: Treatment with Prunus dulcis extract with a dosage of 300 mg/kg accelerated tibial bone healing in rabbits.

Clinical and Radiographic Predictors of Nonunion in Open Tibial Shaft Fractures.

Open fracture is a risk factor for nonunion of diaphyseal tibia fractures. Compared with closed injuries, there is a relative lack of scientific knowledge regarding the healing of open tibia fractures. The objective of this study was to investigate which patient, injury, and surgeon-related factors predict nonunion in open tibial shaft fractures. A cohort of 98 patients with 104 extra-articular open tibial shaft fractures (OTA/AO 41A2-3, 42A-C, and 43A) were treated surgically between 2007 and 2018 at a single level 1 trauma center and were retrospectively reviewed. Patients underwent irrigation and debridement followed by definitive intramedullary nailing or plate fixation. Patient, injury, and perioperative prognostic factors were analyzed as predictors of nonunion based on anteroposterior and lateral radiographs. The nonunion rate was 27.9% (n=29). There were 12 occurrences of deep infection (11.5%). The median follow-up was 14 months. High-energy mechanism of injury (hazard ratio [HR], 5.76), Gustilo-Anderson class IIIA injury (HR, 3.66), postoperative cortical continuity of 0% to 25% (HR, 2.90), early postoperative complication (HR, 4.20), and deep infection (HR, 2.25) were significant predictors of nonunion on univariable analysis (P<.05). On multivariable assessment, only high-energy mechanism of injury, Gustilo-Anderson class IIIA injury, and early postoperative complication reached significance as predictors of nonunion. These data also indicate that lack of cortical continuity is a significant univariable radiographic predictor of nonunion. This is potentially modifiable, may guide surgeons in selecting patients for early bone grafting procedures, and should be assessed carefully in this high-risk population. [Orthopedics. 2021;44(3):142-147.].

The association between intracompartmental pressure and skeletal muscle recovery after tibial diaphyseal fractures: an ambispective cohort study.

BACKGROUND: Due to the special anatomy of the lower leg, tibial diaphyseal fracture causes increased intracompartmental pressure (ICP). Not only is this increased ICP the manifestation of skeletal muscle injury, but it induces further deterioration of the injury. The aim of this study was to assess the association between short-term ICP elevation and long-term skeletal muscle recovery after severe limb trauma. METHODS: In this single-center ambispective cohort study, we retrospectively screened and recruited a cohort of tibial diaphyseal fracture patients with integrated ICP data during the early post-traumatic period, and performed a prospective observational study to evaluate their skeletal muscle recovery through long-term follow-up and MR imaging after the removal of the implants. We analyzed the association between ICP elevation and skeletal muscle recovery using statistical methods. RESULTS: A total of 46 patients with healed fractures underwent intramedullary nail removal and MR imaging. The absolute values of the Pearson product-moment correlation coefficients between various ICP parameters and the cross-sectional area ratio (CSAR) ranged from 0.588 to 0.793, and the correlation coefficients between the ICP parameters and the average T2-weighted signal intensity ratio (T2SIR) varied from 0.566 to 0.775. Statistically significant associations were observed between the ICP parameters and the MR imaging parameters when simple linear regression analysis was performed. Among the ICP parameters, the accumulated ΔP (ΔP = diastolic blood pressure minus ICP) had the highest determination coefficient and explained 62.1% and 59.1% of the variance in CSAR and T2SIR, respectively. CONCLUSIONS: Short-term ICP elevation was associated with long-term skeletal muscle recovery following tibial diaphyseal fracture, especially for ICP data that integrated time factors. LEVEL OF EVIDENCE: Level 3.

Intraoperative 3D imaging in intraarticular tibial plateau fractures - Does it help to improve the patients' outcomes?

BACKGROUND: In tibial plateau fractures (TPF) the restoration of an anatomical joint surface as well as an exact subchondral screw position for postoperative stability is crucial for the outcome. The aim of this study was to determine whether the additional use of an intraoperative 3D imaging intensifier (3D) might help to improve the outcome of complex TPF. METHODS: We performed a retrospective case-control study of a level 1 trauma center. Patients with AO/OTA 41 B3 and C-TPF operated on using a 3D imaging intensifier between November 2015 and December 2018 (3D group) were included. The outcomes of this patients were compared to patients operated without 3D imaging between January 2005 to December 2014 (2D group). The comparison of the groups was performed by matched pair analysis. The functional outcome of both groups was measured by KOOS and Lysholm Score after a follow-up period of at least 12 months. Operation time, infections and postoperative revisions were registered. RESULTS: In total, 18 patients were included in the 3D group (mean age: 51.0± 16.4 years; 12 females) and an equal number of matching partners from the 2D group (mean age: 50.3± 15.2 years; 11 females) were found (p=0.82; p=0.79). We found 9x B3, 2x C1, 1x C2, 6x C3 fractures according to AO/OTA for each group (p=1.00) with comparable ASA score (p=0.27). The mean operation time was 127.9± 45.9 min and 116.1± 45.7 min for the 3D and 2D group (p=0.28). The mean follow-up time was 20.9± 10.7 months for the 3D and 55.5± 34.7 months for the 2D group (p< 0.001). For the 3D group a mean Lysholm overall score of 67.4± 26.8 and KOOS overall score of 72.6± 23.5 could be assessed. In contrast, a mean Lysholm overall score of 62.0± 21.4 and KOOS overall score of 65.8± 21.6 could be measured in the 2D group (p=0.39; p=0.31). Thereby, functional outcome of the 3D group showed a significant higher KOOS Sport/Rec sub score of 54.7± 35.0 in comparison to the 2D group with 26.7± 31.6 (p= 0.01). Postoperative revisions had to be performed in 27.8% of cases in both groups (p=1.00). Due to the 3D imaging an intraoperative revision was performed in 33.3% (6/18). CONCLUSION: In our study we could show that re-reduction of the fracture or implant re-positioning were performed in relevant numbers based on the 3D imaging. This was associated with a midterm clinical benefit in regard to better KOOS Sport/Rec scores. TRIAL REGISTRATION: AZ 488 /20-ek.

Development of a tibial experimental non-union model in rats.

BACKGROUND: Many non-union animal models have been developed to explore the problems surrounding fracture healing. However, the existing models are not perfect and cannot satisfy all non-union studies. This study aimed to make a non-union model of the tibia in rats by cauterization of the posterior of 2 mm on both sides of the fracture end after open osteotomy of the tibia and fixing the fractured tibia with a Kirschner wire 0.8 mm in diameter. METHODS: For this study, 96 female adult Sprague-Dawley (SD) rats were used. The rats underwent surgery to produce a tibial open fracture and were fixed with a 0.8-mm diameter Kirschner wire. In 48 of the rats, the periosteum proximal and distal to the fracture end was cauterized. RESULTS: At 2, 4, 6, and 8 weeks after surgery, radiological and histological analysis showed typical physiological healing in the control group, and the healing rate was 100% at 6 weeks. But the non-union group was characterized by resorption of the fracture ends with few callus formations and no bridging callus formation, and the healing rate was 0% at 8 weeks. CONCLUSIONS: This method represents a reproducible model to create atrophic non-unions. This model provides a new option for studying the basic healing mechanisms and evaluating new therapies for bone regeneration and treatment of non-unions.

Total Knee Arthroplasty with Intra-Articular Resection of Bone for Knee Arthritis Secondary to Malunion of a Tibial Shaft Fracture: A Radiological Evaluation of Correction of the Tibial Deformity.

This retrospective study was aimed to evaluate the clinical outcome and the extent of correction of the tibial deformity by a radiological evaluation following total knee arthroplasty (TKA) combined with intra-articular bone resection, in patients with knee arthritis and ipsilateral malunited tibial fractures. Fifteen patients (15 knees) with severe arthritis of the knee and extra-articular malunion of the tibia were treated using TKA with intra-articular bone resection. The extra-articular deformities in the coronal plane were 10 tibia vara (mean 15°, range 9°-30°), 4 tibia valgum (mean 12°, range 6°-20°), and one double deformity in the tibial shaft. The follow-up duration was 84 months (24-240). At the last follow-up, the mean Knee Society knee and function scores had improved, respectively (p = 0.001). The mean arc of knee motion improved from 97° preoperatively to 118.3° at the last follow-up (p < 0.001). The mean mechanical axis improved from a preoperative 15.5° to 1.5° of varus (p = 0.013). Excluding the patient with a double tibial malunion, in the 10 patients with varus tibial angulations, the tibia vara had improved from 15° preoperatively to 2.6° (p = 0.005). There were no observed complications except for one with a postoperative deep infection. In conclusion, our results indicated that TKA with intra-articular resection of the bone is an effective procedure for the treatment of severe arthritis of the knee with extra-articular malunion of the tibia in the coronal plane (≤30° of varus; ≤20° of valgus).

Dimethyl Fumarate Reduces Oxidative Stress and Pronociceptive Immune Responses in a Murine Model of Complex Regional Pain Syndrome.

BACKGROUND: Complex regional pain syndrome (CRPS) is a highly disabling cause of pain often precipitated by surgery or trauma to a limb. Both innate and adaptive immunological changes contribute to this syndrome. Dimethyl fumarate (DMF) works through the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor and other targets to activate antioxidant systems and to suppress immune system activation. We hypothesized that DMF would reduce nociceptive, functional, and immunological changes measured in a model of CRPS. METHODS: Male C57BL/6 mice were used in the well-characterized tibial fracture model of CRPS. Some groups of mice received DMF 25 mg/kg/d orally, per os for 3 weeks after fracture versus vehicle alone. Homozygous Nrf2 null mutant mice were used as test subjects to address the need for this transcription factor for DMF activity. Allodynia was assessed using von Frey filaments and hindlimb weight-bearing data were collected. The markers of oxidative stress malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were quantified in the skin of the fractured mice using immunoassays along with the innate immune system cytokines IL-1ß and IL-6. The accumulation of IgM in the fractured limbs and lymph node hypertrophy were used as indexes of adaptive immune system activation, and the passive transfer of serum from wildtype fractured mice to B cell-deficient fractured muMT mice (mice lacking B cells and immunoglobulin) helped to assess the pronociceptive activity of humoral factors. RESULTS: We observed that oral DMF administration strongly prevented nociceptive sensitization and reduced uneven hindlimb weight bearing after fracture. DMF was also very effective in reducing the accumulation of markers of oxidative stress, activation of innate immune mediator production, lymph node hypertrophy, and the accumulation of IgM in fractured limbs. The sera of fractured vehicle-treated but not DMF-treated mice conferred pronociceptive activity to recipient mice. Unexpectedly, the effects of DMF were largely unchanged in the Nrf2 null mutant mice. CONCLUSIONS: Oxidative stress and immune system activation are robust after hindlimb fracture in mice. DMF strongly reduces activation of those systems, and the Nrf2 transcription factor is not required. DMF or drugs working through similar mechanisms might provide effective therapy for CRPS or other conditions where oxidative stress causes immune system activation.

Bone Material Strength Index as Measured by Impact Microindentation is Low in Patients with Primary Hyperparathyroidism.

CONTEXT: In primary hyperparathyroidism (PHPT) bone mineral density (BMD) is typically decreased in cortical bone and relatively preserved in trabecular bone. An increased fracture rate is observed however not only at peripheral sites but also at the spine, and fractures occur at higher BMD values than expected. We hypothesized that components of bone quality other than BMD are affected in PHPT as well. OBJECTIVE: To evaluate bone material properties using impact microindentation (IMI) in PHPT patients. METHODS: In this cross-sectional study, the Bone Material Strength index (BMSi) was measured by IMI at the midshaft of the tibia in 37 patients with PHPT (28 women), 11 of whom had prevalent fragility fractures, and 37 euparathyroid controls (28 women) matched for age, gender, and fragility fracture status. RESULTS: Mean age of PHPT patients and controls was 61.8 ±â€…13.3 and 61.0 ±â€…11.8 years, respectively, P = .77. Calcium and PTH levels were significantly higher in PHPT patients but BMD at the lumbar spine (0.92 ±â€…0.15 vs 0.89 ±â€…0.11, P = .37) and the femoral neck (0.70 ±â€…0.11 vs 0.67 ±â€…0.07, P = .15) were comparable between groups. BMSi however was significantly lower in PHPT patients than in controls (78.2 ±â€…5.7 vs 82.8 ±â€…4.5, P < .001). In addition, BMSi was significantly lower in 11 PHPT patients with fragility fractures than in the 26 PHPT patients without fragility fractures (74.7 ±â€…6.0 vs 79.6 ±â€…5.0, P = .015). CONCLUSION: Our data indicate that bone material properties are altered in PHPT patients and most affected in those with prevalent fractures. IMI might be a valuable additional tool in the evaluation of bone fragility in patients with PHPT.

Fracturas avulsivas tibiales del ligamento cruzado posterior fijadas con tornillos: un estudio clínico y radiológico / Screw fixation of posterior cruciate ligament tibial avulsion fractures: a clinical and radiographic study

OBJETIVO: Realizar la evaluación clínica, imagenológica y funcional de pacientes con fracturas avulsivas tibiales del ligamento cruzado posterior (FTALCPs) fijadas con tornillos canulados con técnica abierta. MÉTODOS: Los pacientes con FTALCP operados entre 2010 y 2017 fueron revisados retrospectivamente. Criterios de inclusión: fracturas agudas, desplazadas, test de cajón posterior grado III, lesiones combinadas de rodilla, seguimiento > 12 meses. Se excluyeron pacientes > 65 años, con FTALCPs bilaterales, lesiones del ligamento cruzado posterior (LCP) intrasustancia, test de cajón posterior grados I-II, fracturas expuestas, lesiones neurovasculares, y seguimientos < 12 meses. Objetivo primario: medir la estabilidad clínica mediante test de cajón posterior y radiografía de estrés arrodillada comparativa. Objetivos secundarios: nvaluar la consolidación en radiografías, complicaciones y funcionalidad con las escalas de Lysholm y Tegner. Resultados Se incluyeron 20 pacientes, con edad media de 41 años (rango: 32 a 61 años). El seguimiento promedio fue de 33,9 meses (rango: 12 a 82 meses). La estabilidad clínica mejoró en 93% (cajón posterior postoperatorio grados 0 y I) de los pacientes. La radiografía de estrés arrodillada mostró una diferencia promedio de 2,6 mm (rango: 0,1 mm a 6,8 mm) de traslación posterior al comparar con el lado sano. Todas las fracturas consolidaron. Siete pacientes presentaron complicaciones. El puntaje promedio de la escala de Lysholm al final del seguimiento fue de 85,17. El promedio preoperatorio del puntaje en la escala de Tegner no varió significativamente en comparación con el postoperatorio. CONCLUSIONES: La fijación de fracturas avulsivas tibiales del LCP con tornillos canulados con técnica abierta es efectiva en restaurar la estabilidad posterior y lograr la consolidación ósea. La funcionalidad clínica a mediano plazo es buena, a pesar del alto número de complicaciones y lesiones concomitantes. NIVEL DE EVIDENCIA: tipo IV.

OBJECTIVE: To report mid-term clinical, radiographic, and functional outcomes following open reduction and fixation of posterior cruciate ligament tibial avulsion fractures (PCLTAFs) with cannulated screws. METHODS: This is a retrospective analysis of patients with PCLTAF operated on from August 2010 to April 2017. Patients with acute fractures, with more than 2 mm of displacement and grade III on the posterior drawer test, combined or not to knee injuries, were included. Patients older than 65 years of age, with bilateral avulsion fractures, intrasubstance posterior cruciate ligament (PCL) lesions, stable grade-I to -II on the posterior drawer test, concomitant neurovascular injuries, mid-substance tears, open fractures, and less than 12 months of follow-up were excluded. Primary outcomes: the clinical stability was assessed using the posterior drawer test and a single comparative knee stress radiograph. Secondary outcomes: radiographic consolidation, complications, Lysholm score, and Tegner activity score. RESULTS: In total, 20 patients with a mean age of 41 years (range: 32 to 61 years) were included. The mean follow-up was of 33.9 months (range: 12 to 82 months). Clinical stability (grade 0 or I on the posterior drawer test) was observed in 93% of the patients. The mean difference in contralateral posterior displacement was of 2.6 mm (range: 0.1 mm to 6.8 mm) on a single comparative knee stress radiograph. All fractures presented radiological consolidation. Seven patients developed complications. The mean Lysholm score at the last follow-up visit was of 85.17. The postoperative Tegner activity scores did no vary significantly compared to the preinjury scores. CONCLUSIONS: Cannulated screw fixation of a displaced PCLTAF through a posterior approach restores clinical and radiographic stability and has excellent union rates. The mid-term functional outcomes are good despite the high rates of combined knee lesions and postoperative complications. LEVEL OF EVIDENCE: IV.

Biomechanical Basis of Predicting and Preventing Lower Limb Stress Fractures During Arduous Training.

PURPOSE OF REVIEW: Stress fractures at weight-bearing sites, particularly the tibia, are common in military recruits and athletes. This review presents recent findings from human imaging and biomechanics studies aimed at predicting and preventing stress fractures. RECENT FINDINGS: Peripheral quantitative computed tomography (pQCT) provides evidence that cortical bone geometry (tibial width and area) is associated with tibial stress fracture risk during weight-bearing exercise. The contribution of bone trabecular microarchitecture, cortical porosity, and bone material properties in the pathophysiology of stress fractures is less clear, but high-resolution pQCT and new techniques such as impact microindentation may improve our understanding of the role of microarchitecture and material properties in stress fracture prediction. Military studies demonstrate osteogenic outcomes from high impact, repetitive tibial loading during training. Kinetic and kinematic characteristics may influence stress fracture risk, but there is no evidence that interventions to modify biomechanics can reduce the incidence of stress fracture. Strategies to promote adaptive bone formation, in combination with improved techniques to assess bone strength, present exciting opportunities for future research to prevent stress fractures.

Postoperative lower limb joint kinematics following tibial plateau fracture: A 2-year longitudinal study.

BACKGROUND: The goal of postoperative tibial plateau fracture (TPF) management is to ensure surgical fixation is maintained while returning patients to normal function as soon as possible, allowing patients to resume their normal activities of daily living. The aim of this study was to investigate longitudinal changes in lower limb joint kinematics following TPF and determine how these kinematics relate to self-reported function. METHODS: Patients presenting with a TPF were recruited (n = 18) and undertook gait analysis at six postoperative time points (two weeks, six weeks, three months, six months, one and two years). Lower limb joint kinematics were assessed at each time point based on gait data. Statistical parametric mapping (SPM) was undertaken to investigate the change in joint kinematic traces with time. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was assessed at each time point to obtain self-reported outcomes. A healthy reference was also analyzed and used for qualitative comparison of joint kinematics. RESULTS AND SIGNIFICANCE: Knee kinematics showed improvements with time, however only minor changes were noted after six weeks at the hip, and six months at the knee and ankle relative to two weeks postoperative. SPM identified significant improvements with time in hip (p < 0.001) and knee (p = 0.003) flexion. No significant changes were observed with time at the ankle however, when compared to the healthy reference, participants showed reduced plantarflexion at two years. Lower limb joint ROM showed significant weak to moderate correlation with the ADL sub-scale of the KOOS (hip r = 0.442, knee r = 0.303, ankle r = 0.367). The lack of significant changes with time and overall reduced plantarflexion at the ankle potentially reduces propulsive capacity during gait up to two years postoperative. In this study, we see a deficiency in joint kinematics in TPF patients up to two years when compared to a healthy reference, especially at the ankle.

Virtual mechanical tests out-perform morphometric measures for assessment of mechanical stability of fracture healing in vivo.

Finite element analysis with models derived from computed tomography (CT) scans is potentially powerful as a translational research tool because it can achieve what animal studies and cadaver biomechanics cannot-low-risk, noninvasive, objective assessment of outcomes in living humans who have actually experienced the injury, or treatment being studied. The purpose of this study was to assess the validity of CT-based virtual mechanical testing with respect to physical biomechanical tests in a large animal model. Three different tibial osteotomy models were performed on 44 sheep. Data from 33 operated limbs and 20 intact limbs was retrospectively analyzed. Radiographic union scoring was performed on the operated limbs and physical torsional tests were performed on all limbs. Morphometric measures and finite element models were developed from CT scans and virtual torsional tests were performed to assess healing with four material assignment techniques. In correlation analysis, morphometric measures and radiographic scores were unreliable predictors of biomechanical rigidity, while the virtual torsion test results were strongly and significantly correlated with measured biomechanical test data, with high absolute agreement. Overall, the results validated the use of virtual mechanical testing as a reliable in vivo assessment of structural bone healing. This method is readily translatable to clinical evaluation for noninvasive assessment of the healing progress of fractures with minimal risk. Clinical significance: virtual mechanical testing can be used to reliably and noninvasively assess the rigidity of a healing fracture using clinical-resolution CT scans and that this measure is superior to morphometric and radiographic measures.

Mechanical performance and implications on bone healing of different screw configurations for plate fixation of diaphyseal tibia fractures: a computational study.

Diaphyseal tibia fractures may require plate fixation for proper healing to occur. Currently, there is no consensus on the number of screws required for proper fixation or the optimal placement of the screws within the plate. Mechanical stability of the construct is a leading criterion for choosing plate and screws configuration. However, number and location of screws have implications on the mechanical environment at the fracture site and, consequently, on bone healing response: The interfragmentary motion attained with a specific plate and screw construct may elicit mechano-transduction signals influencing cell-type differentiation, which in turn affects how well the fracture heals. This study investigated how different screw configurations affect mechanical performance of a tibia plate fixation construct. Three configurations of an eight-hole plate were considered with the fracture in the center of the plate: eight screws-screws at first, fourth, fifth and eighth hole and screws at first, third, sixth and eighth hole. Constructs' stiffness was compared through biomechanical tests on bone surrogates. A finite element model of tibia diaphyseal fracture was used to conduct a stress analysis on the implanted hardware. Finally, the potential for bone regeneration of each screw configuration was assessed via the computational model through the evaluation of the magnitude of mechano-transduction signals at the bone callus. The results of this study indicate that having screws at fourth and fifth holes represents a preferable configuration since it provides mechanical properties similar to those attained by the stiffest construct (eight screws), and elicits an ideal bone regenerative response.

Smoking, Obesity, and Disability Benefits or Litigation Are Not Associated with Clinically Important Reductions in Physical Functioning After Intramedullary Nailing of Tibial Shaft Fractures: A Retrospective Cohort Study.

BACKGROUND: Forty percent of long bone fractures involve the tibia. These fractures are associated with prolonged recovery and may adversely affect patients' long-term physical functioning; however, there is limited evidence to inform what factors influence functional recovery in this patient population. QUESTION/PURPOSE: In a secondary analysis of a previous randomized trial, we asked: What fracture-related, demographic, social, or rehabilitative factors were associated with physical function 1 year after reamed intramedullary nailing of open or closed tibial shaft fractures? METHODS: This is a secondary (retrospective) analysis of a prior randomized trial (Trial to Re-evaluate Ultrasound in the Treatment of Tibial Fractures; TRUST trial). In the TRUST trial, 501 patients with unilateral open or closed tibial shaft fractures were randomized to self-administer daily low-intensity pulsed ultrasound or use a sham device, of which 15% (73 of 501) were not followed for 1 year due to early study termination as a result of futility (no difference between active and sham interventions). Of the remaining patients, 70% (299 of 428) provided full data. All fractures were fixed using reamed (298 of 299) or unreamed (1 of 299) intramedullary nailing. Thus, we excluded the sole fracture fixed using unreamed intramedullary nailing. The co-primary study outcomes of the TRUST trial were time to radiographic healing and SF-36 physical component summary (SF-36 PCS) scores at 1-year. SF-36 PCS scores range from 0 to 100, with higher scores being better, and the minimum clinically important difference (MCID) is 5 points. In this secondary analysis, based on clinical and biological rationale, we selected factors that may be associated with physical functioning as measured by SF-36 PCS scores. All selected factors were inserted simultaneously into a multivariate linear regression analysis. RESULTS: After adjusting for potentially confounding factors, such as age, gender, and injury severity, we found that no factor showed an association that exceeded the MCID for physical functioning 1 year after intramedullary nailing for tibial shaft fractures. The independent variables associated with lower physical functioning were current smoking status (mean difference -3.0 [95% confidence interval -5 to -0.5]; p = 0.02), BMI > 30 kg/m2 (mean difference -3.0 [95% CI -5.0 to -0.3]; p = 0.03), and receipt of disability benefits or involvement in litigation, or plans to be (mean difference -3.0 [95% CI -5.0 to -1]; p = 0.007). Patients who were employed (mean difference 4.6 [95% CI 2.0 to 7]; p < 0.001) and those who were advised by their surgeon to partially or fully bear weight postoperatively (mean difference 2.0 [95% CI 0.1 to 4.0]; p = 0.04) were associated with higher physical functioning. Age, gender, fracture severity, and receipt of early physical therapy were not associated with physical functioning at 1-year following surgical fixation. CONCLUSION: Among patients with tibial fractures, none of the factors we analyzed, including smoking status, receipt of disability benefits or involvement in litigation, or BMI, showed an association with physical functioning that exceeded the MCID. LEVEL OF EVIDENCE: Level III, therapeutic study.