Biomechanical evaluation of different medial column fixation patterns for valgus pilon fractures.

BACKGROUND: The purpose of this study was to perform a biomechanical analysis to compare different medial column fixation patterns for valgus pilon fractures in a case-based model. METHODS: Based on the fracture mapping, 48 valgus pilon fracture models were produced and assigned into four groups with different medial column fixation patterns: no fixation (NF), K-wires (KW), intramedullary screws (IS), and locking compression plate (LCP). Each group contained wedge-in and wedge-out subgroups. After fixing each specimen on the machine, gradually increased axial compressive loads were applied with a load speed of one millimeter per minute. The maximum peak force was set at 1500 N. Load-displacement curves were generated and the axial stiffness was calculated. Five different loads of 200 N, 400 N, 600 N, 800 N, 1000 N were selected for analysis. The specimen failure was defined as resultant loading displacement over 3 mm. RESULTS: For the wedge-out models, Group-IS showed less displacement (p < 0.001), higher axial stiffness (p < 0.01), and higher load to failure (p < 0.001) than Group-NF. Group-KW showed comparable displacement under loads of 200 N, 400 N and 600 N with both Group-IS and Group-LCP. For the wedge-in models, no statistical differences in displacement, axial stiffness, or load to failure were observed among the four groups. Overall, wedge-out models exhibited less axial stiffness than wedge-in models (all p < 0.01). CONCLUSIONS: Functional reduction with stable fixation of the medial column is essential for the biomechanical stability of valgus pilon fractures and medial column fixation provides the enough biomechanical stability for this kind of fracture in the combination of anterolateral fixation. In detail, the K-wires can provide a provisional stability at an early stage. Intramedullary screws are strong enough to provide the medial column stability as a definitive fixation. In future, this technique can be recommended for medial column fixation as a complement for holistic stability in high-energy valgus pilon fractures.

Screw placement through a higher medial portal provides better initial stability in arthroscopic ACL tibial avulsion fracture fixation: a finite element analysis.

OBJECTIVE: The objective of this study was to investigate the initial stability of different screw placements in arthroscopic anterior cruciate ligament (ACL) tibial avulsion fracture fixation. METHODS: A three-dimensional knee model at 90° flexion was utilized to simulate type III ACL tibial avulsion fracture and arthroscopic screw fixation through different portals, namely the central transpatellar tendon portal (CTP), anterolateral portal (ALP), anteromedial portal (AMP), lateral parapatellar portal (LPP), medial parapatellar portal (MPP), lateral suprapatellar portal (LSP), medial suprapatellar portal (MSP). A shear force of 450 N was applied to the finite element models at 30° flexion to simulate the failure condition. The displacement of the bony fragment and the volume of the bone above 25,000 µ-strain (damaged bone volume) were calculated around the screw path. RESULTS: When the screw was implanted through CTP, the displacement of the bony fragment reached the maximum displacement which was 1.10 mm and the maximum damaged bone volume around the screw path was 148.70 mm3. On the other hand, the minimum displacement of the bony fragment was 0.45 mm when the screw was implanted through LSP and MSP. The minimum damaged bone volume was 14.54 mm3 around the screw path when the screw was implanted through MSP. CONCLUSION: Screws implanted through a higher medial portal generated less displacement of the bony fragment and a minimum detrimental strain around the screw path. The findings are clinically relevant as they provide biomechanical evidence on optimizing screw placement in arthroscopic ACL tibial avulsion fracture fixation.

Effect of early weight bearing program with conventional physiotherapy on functional outcomes in surgically treated proximal tibia fracture: a pilot randomized controlled trial.

INTRODUCTION: Patients are often instructed to avoid weight bearing on the proximal tibia for 6 - 12 weeks post-surgery to avoid fracture fixation failure. However, delayed weight bearing leads to delayed mobility, causing difficulties in daily activities; problems such as pain, limited knee ROM, reduced quadriceps muscle strength, and impaired functional outcomes are reported in long-term follow-up. This study primarily aimed to evaluate the feasibility and explore the effect size. The secondary aim was to determine the effectiveness of early weight bearing along with conventional physiotherapy on functional outcomes. MATERIALS AND METHODS: A single-blinded pilot randomized controlled trial with 30 participants with proximal tibia type I, II, and III fractures were included; they were randomized using computer-based software. Seven patients were lost to follow-up. Group I received early weight bearing along with conventional physiotherapy whereas Group II received restricted weight bearing along with conventional physiotherapy. Assessments were made on post-operative day 3 (POD-03), at discharge, at 6 weeks, and at 12 weeks. Radiographs were recorded immediately after the operation, at discharge, and at 12 weeks. RESULTS: A full-scale RCT is feasible with an effect size between 0.3 - 0.7. A statistically significant difference (p < 0.05) was found within both groups 12 weeks post-surgery in all outcome measures; the difference was more prominent in the intervention group. A statistically significant difference (p < 0.05) was found between both the groups post-12 weeks in all outcome measures except quadriceps isometric muscle strength. CONCLUSION: A full-scale RCT for early weight bearing along with conventional physiotherapy for patients operated for Type I, II, and III proximal tibia fracture is feasible. Early weight bearing along with conventional physiotherapy could have a positive effect on reducing patient's pain perception and increasing knee joint mobility, quadriceps isometric muscle strength, knee function, and quality of life without any adverse effects. TRIAL REGISTRATION: ClinicalTrialsRegistry.gov (CTRI/2022/10/046797).

Combined vertical and external rotational force in plantarflexion position produces posterior pilon fracture: A preliminary cadaveric study.

BACKGROUND: Posterior pilon fracture is speculated to occur by a combination of rotation and axial load, which makes it different from rotational posterior malleolar fracture or pilon fracture, but is not validated in vitro. The aim of the current study is to investigate the injury mechanisms of posterior pilon fracture on cadaveric specimens. METHODS: Eighteen cadaveric specimens were mounted to a loading device to undergo solitary vertical loading, solitary external rotational loading, and combined vertical and external rotational loading until failure, in initial position of plantarflexion with or without varus. The fracture characteristics were documented for each specimen. RESULTS: Vertical loading force combined with external rotation force diversified the fracture types resulting in pilon fracture, tibial spiral fracture, rotational malleolar fracture, talar fracture or calcaneal fracture. Vertical violence combined with external rotational loading in position of 45° of plantarflexion and 0° of varus produced posterior pilon fracture in specimens No. 13 and 14. CONCLUSION: Combination of vertical and external rotational force in plantarflexion position on cadaveric specimens produce posterior pilon fracture.

Larger lateral hinges increase the probability of Takeuchi type II and III fractures in high tibial osteotomy.

PURPOSE: Lateral hinge fractures are the main complications in the high tibial osteotomy to treat varus deformities. The aim of present study is to answer the question whether the lateral hinge length (H) has an effect on the type of fracture and required force during the opening in high tibia osteotomy. It was hypothesized in this comparative research that extending the hinge length increased opening force and probability of a type II and type III fractures. METHODS: A monoplanar medial open wedge osteotomy with different intact hinge lengths varying from 9 to 32 mm was performed in 20 ostrich bones. A biomechanical experiment using unidirectional tensile testing apparatus was performed to open the wedge, and the required force was increased until a 10 mm opening was reached; then, the presence of fracture in the lateral cortex and its direction were evaluated. Lateral hinge fracture type based on direction was classified as suggested by Takeuchi et al. RESULTS: Fracture that grows along the osteotomy line (type I) was observed in 4 samples with the mean hinge length (H) of 11 ± 1.54 mm. For seven bones with Takeuchi fracture type II, with downward crack propagation, the mean H was 16 ± 3.36 mm. For the mean H of 25 ± 6.53 mm, the crack propagated upward to the cutting path, displaying a Takeuchi type III fracture in seven samples. The statistical analysis showed that the fracture type significantly depends on the hinge length (P value < 0.05). Also, the mean opening force significantly increased with hinge lengthening (P value < 0.05). The peak forces at crack initiation were 41.8 ± 21.9, 115.2 ± 41.5, and 167 ± 135.3 N, respectively, for the fracture types I, II, and III samples. CONCLUSION: The lateral cortical hinge length was significantly associated with hinge fracture type. The experimental tests indicated that the hinge lengthening increases the risk of type II and III fractures, as classified by Takeuchi.

Torsion constants and virtual mechanical tests are valid image-based surrogate measures of ovine fracture healing.

In large animal studies, the mechanical reintegration of the bone fragments is measured using postmortem physical testing, but these assessments can only be performed once, after sacrifice. Image-based virtual mechanical testing is an attractive alternative because it could be used to monitor healing longitudinally. However, the procedures and software required to perform finite element analysis (FEA) on subject-specific models for virtual mechanical testing can be time consuming and costly. Accordingly, the goal of this study was to determine whether a simpler image-based geometric measure-the torsion constant, sometimes known as polar moment of inertia-can be reliably used as a surrogate measure of bone healing in large animals. To achieve this, postmortem biomechanical testing and microCT scans were analyzed for a total of 33 operated and 20 intact ovine tibiae. An image-processing procedure to compute the attenuation-weighted torsion constant from the microCT scans was developed in MATLAB and this code has been made freely available. Linear regression analysis was performed between the postmortem biomechanical data, the results of virtual mechanical testing using FEA, and the torsion constants measured from the scans. The results showed that virtual mechanical testing is the most reliable surrogate measure of postmortem torsional rigidity, having strong correlations and high absolute agreement. However, when FEA is not practical, the torsion constant is a viable alternative surrogate measure that is moderately correlated with postmortem torsional rigidity and can be readily calculated.

Biomechanical comparisons of plate placement for medial tibial plateau fractures (Schatzker type IV): A biomechanical study using porcine tibias.

INTRODUCTION: Biomechanical studies on medial tibial plateau fractures (MTPFs) (Schatzker classification type IV) are currently few, while studies using locking plates (LPs) placed on medial proximal tibias are unavailable. Hence, we compared the biomechanical properties of plate osteosynthesis at the medial and anteromedial placements using large- and small-fragment LPs in porcine bones. MATERIALS AND METHODS: MTPFs were internally fixed using LPs on 40 porcine tibias. Specimens were equally divided into four groups: medial placement using a large-fragment LP (LPs for the medial (LM) group), anteromedial placement using a large-fragment LP (LAM group), medial placement using a small-fragment LP (SM group), and anteromedial placement using a small-fragment LP (SAM group). The translation patterns of the constructs in each group were examined by cycling loading test (displacement and translation along the mechanical axis at 10-100, 100-500, 500-1000, 1000-1500, and 1500-2000 cycles). Then, articular gaps and step-off changes after 2000 cycles were compared among the four groups. RESULTS: One-way analysis of variance (ANOVA) revealed no significant differences in displacement and translation during cyclic loading. One-way ANOVA followed by post hoc analysis revealed that the anterior gap was lower in LPs for the medial (LM) than in SM (P = 0.029) and SAM (P = 0.0026). The central gap was also lower in LM than in SM (P = 0.042) and SAM (P < 0.001), and it was lower in LAM than in SAM (P = 0.047). Likewise, the posterior gap was lower in LM than in LAM (P = 0.025) and SAM (P < 0.001). Furthermore, the central step-off of SAM was higher than that of LM, LAM, and SM (P < 0.001, P = 0.0014, and P = 0.0077, respectively). The posterior step-off was lower in LM than in SAM and LAM (P = 0.037 and P < 0.001), and it was also lower in SM than in SAM (P = 0.0082). CONCLUSION: Medial LP placement for MTPFs in porcine bones resulted in significantly lower posterior step-offs after cyclic loading than anteromedial placement, and large-fragment LPs for MTPFs caused significantly lower fracture gaps in the central articular after cyclic loading than small-fragment LPs.

Longitudinal CT-based finite element analyses provide objective fracture healing measures in an ovine tibia model.

Measuring the healing status of a bone fracture is important to determine the clinical care a patient receives. Implantable devices can directly and continuously assess the healing status of fracture fixation constructs, while subject-specific virtual biomechanical tests can noninvasively determine callus structural integrity at single time points. Despite their potential for objectification, both methods are not yet integrated into clinical practice with further evidence of their benefits required. This study correlated continuous data from an implantable sensor assessing healing status through implant load monitoring with computer tomography (CT) based longitudinal finite element (FE) simulations in a large animal model. Eight sheep were part of a previous preclinical study utilizing a tibial osteotomy model and equipped with such a sensor. Sensor signal was collected over several months, and CT scans were acquired at six interim time points. For each scan, two FE analyses were performed: a virtual torsional rigidity test of the bone and a model of the bone-implant construct with the sensor. The longitudinal simulation results were compared to the sensor data at corresponding time points and a cohort-specific empirical healing rule was employed. Healing status predicted by both in silico simulations correlated significantly with the sensor data at corresponding time points and correctly identified a delayed and a nonunion in the cohort. The methodology is readily translatable with the potential to be applied to further preclinical or clinical cohorts to find generalizable healing criteria. Virtual mechanical tests can objectively measure fracture healing progressing using longitudinal CT scans.

Toddler fractures immobilisation and complications: A retrospective review.

BACKGROUND: A Toddler's Fracture (TF) is classically an isolated, nondisplaced, distal-third diaphyseal tibial spiral fracture in younger children. A TF is stable and has a low risk of complication. There is lack of uniformity as to the optimal treatment for TF. Immobilisation with full above knee casting, below knee casting, splinting, controlled ankle motion boots and no immobilisation are all strategies currently in use. There is limited data from European centres regarding those treated without immobilisation. METHODS: A retrospective review of electronic medical and radiology records was performed to identify all children presenting to a multisite department of paediatric emergency medicine in Ireland from January to December 2022. Those with radiologically confirmed TF or a presumptive diagnosis of TF were included. Data retrieved for each child included initial treatment and the number of and reason for ED reattendances relating to the injury in the 6-month period following the injury. RESULTS: 166 children were identified, 96 with radiologically confirmed TF and 70 with presumptive diagnosis TF. Girls accounted for 47 % of presentations. Fall from a standing height (33 %) was the most common mechanism. 13 % (22/166) children were managed without immobilisation. Those with radiologically confirmed fracture (91/96) were significantly more likely to be immobilised than those with a presumptive diagnosis (53/70) (p = 0.001). In total 28 patients (17 % of total) represented to the ED within 6 months. The representation rate in those immobilised was 17 %, while in those not immobilised was 13 % (p = 0.66). CONCLUSION: In this cohort, those with no radiological evidence of fracture are more likely to be managed without immobilisation. There was no significant difference in PED representations between those immobilised and not immobilised.

Tibial plateau fracture morphology based on injury force mechanism is predictive for patient-reported outcome and conversion to total knee arthroplasty.

PURPOSES: The aim of this study was to assess the relationship between injury mechanism-based fracture patterns and patient-reported outcome as well as conversion rate to total knee arthroplasty (TKA) at follow-up. METHODS: A multicenter cross-sectional study was performed including 1039 patients treated for a tibial plateau fracture between 2003 and 2019. At a mean follow-up of 5.8 ± 3.7 years, patients completed the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. For all patients, the injury force mechanism was defined based on CT images. Analysis of variance (ANOVA) was used to assess the relationship between different injury mechanisms and functional recovery. Cox regression was performed to assess the association with an increased risk on conversion to TKA. RESULTS: A total of 378 (36%) patients suffered valgus-flexion, 305 (29%) valgus-extension, 122 (12%) valgus-hyperextension, 110 (11%) varus-flexion, 58 (6%) varus-hyperextension, and 66 (6%) varus-extension injuries. ANOVA showed significant different KOOS values between injury fracture patterns in all subscales (P < 0.01). Varus-flexion injuries had the lowest average KOOS scores (symptoms 65; pain 67; ADL 72; sport 35; QoL 48). Varus-flexion mechanism was associated with an increased risk on a TKA (HR 1.8; P = 0.03) whereas valgus-extension mechanism was associated with a reduced risk on a TKA (HR 0.5; P = 0.012) as compared to all other mechanisms. CONCLUSION: Tibial plateau fracture patterns based on injury force mechanisms are associated with clinical outcome. Varus-flexion injuries have a worse prognosis in terms of patient-reported outcome and conversion rate to TKA at follow-up. Valgus-extension injuries have least risk on conversion to TKA.

The validation of computed tomography derived radiodensity measurements of bone healing using histopathology.

BACKGROUND: The early identification of delayed bone healing or a non-union is vital for prompt treatment and superior patient outcomes. Current techniques rely heavily on operator skill for interpretation and hence their reliability and repeatability may be inconsistent. This study assessed the application of computed tomography (CT) derived densiometric measurements as a quantitative tool for the assessment of bone healing. METHODS: This prospective, longitudinal, method comparison study was performed using a recognised sheep tibial ostectomy model. Secondary bone healing was assessed at 2, 4, 6, and 8 weeks after the ostectomy was performed. CT densiometric measures of bone healing (Hounsfield units) were taken of the cis, trans, cranial and caudal cortices relative to the bone plate, with histological measurements (percentage of ossification) sourced from the same areas. Cis cortical densiometric data points were excluded from analysis due to significant beam hardening artefact from the bone plate (P < 0.001). A univariable linear regression was performed on the remaining data using averaged radiodensity (independent variable) and histomorphometric (dependent variable) measurements. RESULTS: The two measurements were significantly correlated (R2 = 0.623, P = 0.020) with a clear positive trend identified. CONCLUSION: This study suggests that radiodensity measurements may be a useful diagnostic and management tool for the monitoring of indirect bone healing.

Are extra locking bolts or fibular plating more important in extreme nailing of distal tibia fractures? A cadaveric biomechanical analysis.

OBJECTIVES: In far-distal extra-articular tibia fracture "extreme" nailing, debate surrounds the relative biomechanical performance of plating the fibula compared with extra distal interlocks. This study aimed to evaluate several constructs for extreme nailing including one interlock (one medial-lateral interlock), one interlock + plate (one medial-lateral interlock with lateral fibula compression plating), and two interlocks (one medial-lateral interlock and one anterior-posterior interlock). METHODS: Fifteen pairs of fresh cadaver legs were instrumented with a tibial nail to the physeal scar. A 1 cm segment of bone was resected from the distal tibia 3.5 cm from the joint and an oblique osteotomy was made in the distal fibula. We loaded specimens with three different distal fixation constructs (one interlock, one interlock + plate, and two interlocks) through 10,000 cycles form 100N-700 N of axial loading. Load to failure (Newtons), angulation and displacement were also measured. RESULTS: Mean load to failure was 2092 N (one interlock), 1917 N (one interlock + plate), and 2545 N (two interlocks). Linear mixed effects modeling demonstrated that two interlocks had a load to failure 578 N higher than one interlock alone (95 % CI, 74N-1082 N; P = 0.02), but demonstrated no significant difference between one interlock and one interlock + plate. No statistically significant difference in rates or timing of displacement >2 mm or angulation >10° were demonstrated. CONCLUSIONS: When nailing far-distal extra-articular tibia and fibula fractures, adding a second interlock provides more stability than adding a fibular plate. Distal fibula plating may have minimal biomechanical effect in extreme nailing.

Fixation of Proximal Tibial Fractures with Intramedullary Nail and Immediate Weightbearing: A Beneficial Alternative.

Newer intramedullary (IM) nails have become another option in the fixation of proximal tibia fractures. There is limited data on the successful use of these implants in intra-articular and extra-articular fractures of the proximal tibia, and no studies assessing the ability of these implants to maintain alignment with early weight bearing. Our objective was to determine whether immediate weight bearing after IM fixation, with or without supplemental plate or screw fixation, of proximal third tibial fractures (OTA/AO 41A-C) results in a change in alignment prior to union. 35 patients with 39 proximal tibia fractures from 2015 to 2020, all treated with IM nailing with or without supplemental plate or screw fixation, all made weight-bearing as tolerated following surgery, were included. The main outcomes were change in medial proximal tibial angle (MPTA) and posterior proximal tibial angle (PPTA) from initial post-operative films to final follow up. 12 fractures were OTA/AO 41 type A, 14 were type B, and 13 were type C. Mean initial MPTA was 87.0 +/-2.53 degrees, while mean initial PPTA was 79.6 +/- 3.50 degrees. The mean change in MPTA was 0.048 +/- 2.8 degrees (P=0.92), and mean change in PPTA was 0.264 +/- 3.67 degrees. 92.3% of fractures had normal final coronal plane alignment, with MPTA between 85.0 and 90.0 degrees. 89.7% of fractures had normal final sagittal plane alignment, with PPTA between 77.0 and 84.0 degrees. No patients required reoperation for malalignment. In OTA/AO type 41 fractures, immediate weight bearing after IM nail fixation, with or without supplemental plate or screw fixation when indicated, leads to minimal change in final coronal or sagittal alignment, and was well tolerated in most patients. [authors blinded for review].

Percutaneous injection of autologous platelet gel accelerate healing in diabetic tibial non union: On going longitudinal study.

INTRODUCTION: In this study the tibial shaft fracture non unions in diabetes mellitus are evaluated with percutaneous autologous platelet gel supplementation to accelerate union are compared with individually matched control group with autologous iliac crest bone marrow aspirate injection. MATERIAL AND METHODS: This present study was carried out on tibial non unions in diabetic patients recruited in an ongoing longitudinal study over a period of 2006 to 2017, treated by one surgeon at one institute, are included in this report. Each of 18 established tibial atrophic, aseptic non unions treated by percutaneous autologous platelets and iliac crest bone marrow aspirate were followed up on regular basis up till 9 months. The healing of non union was assessed clinically by painless full weight bearing and the radiological union was judged by bridging callus formation observed on at least 3 of 4 cortices in anteroposterior and lateral views. RESULTS: Union was observed in 17 (94.4 %) patients of the autologous platelet group. The average time to union was 9.2 weeks (range 8 to 18 weeks) after percutaneous autologous platelet injection (P < 0.0517) .In the control group, union was observed in 14 (77.8 %) patients (P = 0.672). The average time to union following percutaneous bone marrow injection was 11.6 weeks (range 9 to 28 weeks). The proximal 1/3 shaft non union healed comparatively faster than the distal 1/3 shaft tibia (P ≤ 0.0612). No correlation was observed between the comminuted and non comminuted fracture non union (P = 0.789). A significant correlation was noted as regards the non union healing time duration in patients who were on insulin and oral hypoglycemic drugs (P ≤ 0.001) and also about the total duration of diabetes mellitus in years (P ≤ 0.003). CONCLUSION: This investigation showed that percutaneous autologous platelet gel delivery is sufficient method to obtain union in diabetic tibial fracture non unions, which is less invasive procedure than bone marrow injection. The efficacy of this autologous platelets is once again well established and this study reinforced categorically the previously published report by the author.

Osteosynthesis by locking plate for proximal tibial fractures.

INTRODUCTION: Treatment of proximal tibial fractures is known to be difficult. We report our own experience of the treatment of these fractures and evaluate our results. The hypothesis was that the clinical and radiological results were good. MATERIAL AND METHOD: From January 2004 to October 2008, fourteen AO-type 41A2-3 and C1 fractures have been treated with a LCP locking plate (8 women and 6 men, average age 60.42). Plating was performed either with an open approach or a minimal invasive approach. Clinical and radiological follow-up was carried out looking for range of motion of the knee joint and autonomy level. RESULTS: Mean follow-up was 32.63 months (12-70). Range of motion was maintained with a mean arch of 117.5° Autonomy was maintained in all cases. Professional, domestic and sports activities were unchanged. No infection or general complication occurred. Bone fusion was obtained in all cases after an average of 13.28 weeks. 6° of valgus deformation, already seen immediately postoperatively was observed once. Secondary displacement was observed in 6 cases, with an average of 2.83° DISCUSSION-CONCLUSION: We report good radiological results, with only one initial malalignment. The hypothesis was confirmed. However, X-ray analysis at consolidation shows 6 secondary displacements, without any satisfactory explanation. Though the clinical consequences of these malunions are minimal. Osteosynthesis with plate, in the sight of this study, yields good clinical results. Radiological evolution concerning the evolution of bone axes puts the emphasis on careful operative technique and adequate time to weight bearing. LEVEL OF EVIDENCE: retrospective study, IV.

Evaluation of distal tibia slope in pilon fractures after surgical fixation.

INTRODUCTION: Alteration of sagittal alignment during fracture fixation directly impacts ankle motion in dorsiflexion and plantarflexion. Previously research measured the anterior distal tibia angle (ADTA) in a normal healthy population. The null hypothesis for this study is that ADTA is restored to normal range following unstable pilon fractures. The aim of this study is to identify the range of the ADTA in distal tibia fractures after surgical fixation, compared to a previously published normal population. MATERIAL AND METHODS: A retrospective review of operative distal tibia fractures (AO/OTA classification 43A and 43C - 43B were excluded due to lower likelihood of fracture changing the ADTA) was performed. ADTA on lateral radiograph was measured as the angle relative to the tibia shaft. RESULTS: 100 patients with post-operative radiographs that met inclusion criteria were analyzed. The average ADTA was 6.9° (⌠=4.62°) with a maximum slope of 19.2° (i.e. anterior orientation) and a minimum of -3.3° (i.e. posterior orientation). The uninjured population had an average ADTA of 6.0° (range -2.0°-14°, ⌠=3.0°). CONCLUSION: This analysis shows the average distal tibia sagittal alignment in the post-surgical group is similar to a normal, uninjured population. Large alterations in ADTA would directly impact the ankle in the plane of motion (i.e. negative ADTA would decrease ankle dorsiflexion). Considering ADTA as an objective intra-operative parameter optimizes sagittal plane alignment.

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.

Modelo predictivo de la no unión de tibia / Tibia non union predictive model

OBJETIVOS: Estimar un modelo predictivo para la no-unión en pacientes que presentan fractura de tibia. MATERIALES Y MÉTODOS: Estudio de cohorte retrospectivo, en pacientes con fractura de tibia operadas entre 2012 y 2018, con un mínimo de 12 meses de seguimiento, excluyendo amputaciones traumáticas. Realizamos un modelo de regresión logística con 13 variables descritas en la literatura. Se descartaron las variables estadísticamente no significativas y las que no causaban efecto de confusión. Se evaluó la bondad de ajuste mediante el test de Hosmer-Lemeshow y la discriminación del modelo con la curva ROC. RESULTADOS: Se incluyeron 411 fracturas de tibia, las variables estadísticamente significativas fueron: exposición ósea OR » 2,57(IC:1,15­5,75, p » 0,022), diabetes OR » 3,29 (IC:1,37­7,91, p » 0,008) y uso de tutor externo OR » 1,77(IC:0,81­3,85), el que tuvo efecto de confusión. La bondad de ajuste demostró que los datos se ajustan adecuadamente al modelo (p » 0,35). La curva ROC demuestra un 70,91% de poder discriminatorio. Al evaluar aisladamente las fracturas expuestas, no hubo asociación estadísticamente significativa con ninguna variable. DISCUSIÓN: Al evaluar el modelo, obtuvimos una asociación estadísticamente significativa entre: no unión, exposición ósea, diabetes y uso de tutor externo, información concordante con la literatura. Al estudiar el subgrupo de fracturas expuestas, las demás variables son estadísticamente no significativas. Eso refleja que la exposición ósea es la variable que confiere mayor riesgo. El seguimiento adecuado de esos pacientes es fundamental dado este alto riesgo de evolucionar con no-unión. CONCLUSIÓN: En nuestra serie, la exposición ósea es el factor de riesgo más importante para presentar no unión de tibia.

OBJECTIVES: Estimate a predictive model for non-union in patients presenting with a tibial fracture. MATERIALS AND METHODS: Retrospective cohort study in patients with tibia fractures operated between 2012 and 2018, with a minimum follow-up of 12 months, excluding traumatic amputations. We performed a multivariate logistic regression model with 13 variables described in the literature. The variables that were statistically non-significant and those variables that do not cause confusion, were discarded. Goodness of fit was evaluated using the Hosmer-Lemeshow test and the discrimination of the model with the ROC curve. RESULTS: 411 tibial fractures were included, the statistically significant variables were: bone exposure OR » 2.57(CI:1.15­5.75, p » 0.022), diabetes OR » 3.29(CI:1.37­7.91, p » 0.008) and use of external fixation OR » 1.77(CI:0.81­3.85), being included in the model because of its confounding effect. Goodness of fit demonstrates that the data fit the model adequately(p » 0.35). The ROC curve demonstrates 70.91% discriminatory power. When evaluating the exposed fractures in isolation, there was no statistically significant association with any variable. DISCUSSION: When evaluating the model, we obtained a statistically significant association between non-union, bone exposure, diabetes and use of external fixation, being consistent with the literature. When studying the subset of exposed fractures, the other variables are statistically non-significant. This reflects that bone exposure is the variable that confers the greatest risk. Proper follow-up of these patients is essential given this high risk of evolving with non-union. CONCLUSION: In our series, bone exposure is the most important risk factor for presenting tibial non-union.

Seudoartrosis atrófica: Efecto de la aplicación de ondas de choque extracorpóreas en un modelo experimental en tibia de conejos / Atrophic pseudoartrosis. Effect of extracorporeal shock waves application in an experimental model in tibia of rabbits

Introducción: Los efectos de las ondas de choque extracorpóreas se han investigado en osteoblastos humanos, focos fracturarios, seudoartrosis y células periósticas. Los mejores resultados del tratamiento de la seudoartrosis con ondas de choque extracorpóreas se han documentado para seudoartrosis hipertróficas. El objetivo de este estudio fue investigar el efecto de la terapia con ondas de choque extracorpóreas sobre un foco de seudoartrosis "atrófica" generado en tibia de conejo. Métodos: Se establecieron tres grupos: A, fracturados sometidos a ondas de choque extracorpóreas; B ("control"), fracturados no sometidos a ondas de choque y C, no fracturados (pierna derecha). Se trataron 37 conejos (cuniculus NV) blancos y esqueléticamente maduros de Nueva Zelanda. Se practicó la cauterización del periostio con electrobisturí bipolar en una extensión de 20 mm, en ambos muñones óseos (proximal y distal). Luego se aplicaron ondas de choque extracorpóreas en una sola sesión. Se realizaron tinciones con hematoxilina-eosina. Se efectuó el análisis biomecánico con un método de carga a "3 puntos". Se estudiaron la carga máxima aplicada y el módulo de elasticidad para cada grupo. Resultados: El estudio histológico permitió registrar signos de consolidación -callo fracturario perióstico y endostal- considerablemente mayores en las tibias de los animales del grupo A (tratado con ondas de choque extracorpóreas) que en las del grupo B "control". Conclusión: En un modelo experimental original de seudoartrosis atrófica generada por electrocauterización en tibia de conejos, se registraron cambios significativos radiográficos e histológicos luego de la intervención del foco mediante ondas de choque extracorpóreas. Nivel de Evidencia: II

Introduction: The effects of extracorporeal shock wave therapy (ESWT) have been investigated in human osteoblasts, fracture foci, nonunion and periosteum cells. The best results of nonunion treatment with ESWT have been documented for hypertrophic type. The objective of this study was to investigate the effects of ESWT in an atrophic nonunion focus generated in a rabbit tibia model. Methods: Three groups were included: A, fractures receiving ESWT; B ("control"), fractures not receiving ESWT, and C, no fractures (right leg). A total of 37 New Zealand white and skeletally mature rabbits (cuniculus NV) were treated. Periosteum was cauterized using bipolar electrocautery at 20 mm in both bone stumps (proximal and distal). Then ESWT was applied in one session. Staining with hematoxylin-eosin was used. A biomechanical analysis with a 3-point loading system was performed. Maximum load and elastic modulus were evaluated in each group. Results: Histological study evidenced signs of union (periosteal and endosteal fracture callus) which were considerably larger in tibias of Group A (treated with ESWT) as compared to the control group (Group B). Conclusion: In an experimental model of atrophic pseudarthrosis caused by electrocautery in tibias of rabbits, significant radiographic and histological changes were observed after focus intervention with the application of ESWT. Level of Evidence: II

Analysis of fracture healing in osteopenic bone caused by disuse: experimental study

Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.