Anatomical variation in humeri: gender and side comparison using statistical shape modelling.

PURPOSE: The surgical management of proximal humeral fractures remains challenging. Anatomical reduction of the fracture has been reported as the keystone for a sufficient surgical fixation and successful outcome. However, mostly there is no example of its premorbid state. Literature suggests that the mirrored contralateral side can be used as a reconstruction template. But is this a correct technique to use? The purpose of this study is to define anatomical variation between humeri based on gender and side comparison. METHODS: Two different statistical shape models of the humerus were created and their modes of variation were described. One model contained 110 unpaired humeri. The other model consisted of 65 left and corresponding right humeri. RESULTS: The compactness of the statistical shape model containing 110 humeri showed that two principal components explain more than 95% of the variation and the generalization showed that a random humerus can be described with an accuracy of 0.39 mm. For only three parameters, statistically significant differences were observed between left and right. However, comparing the mean of the different metrics on the humeri of men and women, almost all were significant. CONCLUSION: Since there were only small differences between left and right humeri, using the mirrored contralateral side as a reconstruction template for fracture reduction can be defended. The variable anatomy between men and women could explain why locking plates not always fit to the bone.

Patient-specific instrumentation in total knee arthroplasty: a review of the current literature.

Total knee arthroplasty (TKA) is one of the most frequently performed interventions in the field of Orthopaedic surgery. Over the last decades the implantation technique has improved continuously. The majority of patients is satisfied with the clinical outcome of TKA. However in various clinical follow-ups, up to 20% of unsatisfied patients can be observed. Periprosthetic infection and aseptic loosening seem to be the most common reasons for failure. Malalignment has been discussed as a cause of aseptic loosening and often leads to revision surgery. In order to increase the precision of implant positioning and alignment, new technologies such as patient-specific instrumentation (PSI) have been developed. Since the introduction of PSI, multiple clinical studies have been performed analyzing the clinical and radiological outcome of TKA with PSI technique. This review covers the recent literature of PSI in respect to surgical accuracy, clinical outcome, time- and cost-effectiveness.

Statistical Morphology and Fragment Mapping of Complex Proximal Humeral Fractures.

Background and Objectives: Proximal humerus fractures (PHFs) are common in the elderly, but the treatment results are often poor. A clear understanding of fracture morphology and distribution of cortical bone loss is important for improved surgical decision making, operative considerations, and new implant designs. The aim of this study was to develop a 3D segmentation fracture mapping technique to create a statistical description of the spatial pattern and cortical bone loss of complex PHFs. Materials and Methods: Fifty clinical computed tomography (CT) scans of complex PHFs and their contralateral intact shoulders were collected. In-house software was developed for semi-automated segmentation and fracture line detection and was combined with manual fracture reduction to the contralateral template in a commercial software. A statistical mean model of these cases was built and used to describe probability maps of the fracture lines and cortical fragments. Results: The fracture lines predominantly passed through the surgical neck and between the tuberosities and tendon insertions. The superior aspects of the tuberosities were constant fragments where comminution was less likely. Some fracture lines passed through the bicipital sulcus, but predominantly at its edges and curving around the tuberosities proximally and distally. Conclusions: A comprehensive and systematic approach was developed for processing clinical CT images of complex fractures into fracture morphology and fragment probability maps and applied on PHFs. This information creates an important basis for better understanding of fracture morphology that could be utilized in future studies for surgical training and implant design.

One size may not fit all: patient-specific computational optimization of locking plates for improved proximal humerus fracture fixation.

BACKGROUND: Optimal treatment options for proximal humerus fractures (PHFs) are still debated because of persisting high fixation failure rates experienced with locking plates. Optimization of the implants and development of patient-specific designs may help improve the primary fixation stability of PHFs and reduce the rate of mechanical failures. Optimizing the screw orientations in locking plates has shown promising results; however, the potential benefit of subject-specific designs has not been explored yet. The purpose of this study was to evaluate by means of finite element (FE) analyses whether subject-specific optimization of the screw orientations in a fixed-angle locking plate can reduce the predicted cutout failure risk in unstable 3-part fractures. METHODS: FE models of 19 low-density proximal humeri were generated from high-resolution computed tomographic images using a previously developed and validated computational osteosynthesis framework. The specimens were virtually osteotomized to simulate unstable malreduced 3-part fractures and fixed with the PHILOS plates using 6 proximal locking screws. The average principal compressive strain in cylindrical bone regions around the screw tips-a biomechanically validated surrogate for the risk of cyclic screw cutout failure-was defined as the main outcome measure. The angles of the 6 proximal locking screws were optimized via parametric analysis for each humerus individually, resulting in subject-specific screw orientations (SSO). The average peri-implant strains of the SSO were statistically compared with the previously reported cohort-specific (CSO) and original PHILOS screw orientations (PSO) for females vs. males. RESULTS: The optimized SSO significantly reduced the peri-screw bone strain vs. CSO (6.8% ± 4.0%, P = .006) and PSO (25.24% ± 7.93%, P < .001), indicating lower cutout risk for subject-specific configurations. The benefits of SSO vs. PSO were significantly higher for women than men. CONCLUSION: The findings of this study suggest that subject-specific optimization of the locking screw orientations could lead to lower cutout risk and improved PHF fixation. These computer simulation results require biomechanical and clinical corroboration. Further studies are needed to evaluate whether the potential benefit in stability could justify the increased efforts related to implementation of individualized implants. Nevertheless, computational exploration of the biomechanical factors influencing the outcome of fracture fixations could help better understand the fixation failures and reduce their incidence.

Patient-reported outcomes after primary rotating hinge total knee arthroplasty: a multi-centre clinical cohort study.

PURPOSE: Rotating hinge prostheses for total knee arthroplasty (TKA) are mostly used in revision setting; however, evidence on the use of these constrained devices in primary setting is scarce and inconsistent. Therefore, we aimed to evaluate the functional outcomes after third-generation rotating hinge implants in primary TKA with a minimal follow-up of two years in a large dual-centre observational retrospective clinical trial. METHODS: The hospital databases of two centres were searched for primary rotating hinge arthroplasty from January 2007 to January 2015. A minimum follow-up of at least two years was assured. Patients meeting the inclusion criteria were asked to fill out two self-reported functional scores, the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS), to measure the functional status of the knee. RESULTS: In total, 267 primary rotating hinge knee arthroplasties in 242 patients were performed in two centres. The three major indications were axial malalignment (valgus/varus > 15°), 87/267 (33%), persistent ligamentous instability (28%) and neuromuscular disorders (12%). 184 patients with 202 primary rotating hinge knee arthroplasties could be included that provided data of the self-reported outcome measures (OKS and FJS). A mean OKS score of 37.71 (± 9.23) and a mean FJS score of 63.65 (± 31.01) could be obtained. CONCLUSION: This large clinical study suggests that constrained devices provide the best results when treating bone-on-bone tricompartimental osteoarthritis of the knee with severe axial deviation (valgus/varus > 15°) and/or persistent ligamentous instability.

A case of an atraumatic implant failure after primary rotating-hinge total knee arthroplasty.

Rotating-hinge knee implants are fully constrained knee prostheses commonly used for revision total knee arthroplasty. Nevertheless, rotating-hinge devices have been increasingly utilized in primary setting. Complications are inevitable in orthopedic surgery, however, implant breakage after RHK arthroplasty has been rarely described in medical literature. We present a rare case of 70-year-old Caucasian, male patient who suffered an atraumatic femoral stem breakage in a primary NexGen ® Rotating Hinge Knee (Zimmer-Biomet ® , Warsaw, IN, USA).

Failure after proximal humeral fracture osteosynthesis: a one year analysis of hospital-related healthcare cost.

PURPOSE: The issue of rising healthcare costs and limited resources is a topic of worldwide discussion over the last several decades. We hypothesized that failure of proximal humeral fracture osteosynthesis is presumed to be an important determinant in healthcare resources and related costs. The aim of this study was to calculate the total hospital-related healthcare cost of proximal humeral fracture osteosynthesis over one  year focusing on failure. METHODS: A total of 121 patients with a proximal humeral fracture treated by angular stable osteosynthesis were included in this retrospective study. All hospital-related healthcare costs were investigated. Five main hospital-related cost categories were defined: hospitalization cost, honoraria, day care admission, materials, and pharmaceuticals. RESULTS: A total healthcare cost of € 1,139,448 was calculated for the whole patient group. Twelve patients needed revision surgery due to complications or fixation-related failure. This failure rate alone costed € 190,809 of the healthcare resources. In other words, failure after proximal humeral fracture osteosynthesis costed 17% of the total healthcare expenditure inone year. CONCLUSION: This study demonstrates that a high amount of hospital-related healthcare resources is spent because of failure after proximal humeral fracture osteosynthesis. Further research is necessary and should investigate on how to prevent failure. This is not only in the patient's interest, but it is also of great importance for maintaining a healthy healthcare system.

Short-term outcome trapeziectomy with ligament reconstruction and tendon interposition versus trapeziometacarpal prosthesis : a literature review.

Trapeziectomy with ligament reconstruction and tendon interposition and trapeziometacarpal prosthesis are two commonly used procedures for first carpometacarpal joint osteoarthritis. The purpose of this study is to compare the short-term outcome of trapeziectomy with ligament reconstruction and tendon interposition to trapeziometacarpal prosthesis. Pubmed, Cochrane library and science direct database were searched with adequate search terms. Used parameters were force, pain, mobility, functionality and complication. All papers describing short-term outcome of ligament reconstruction and tendon interposition or trapeziometacarpal prosthesis were included in this review. Trapeziometacarpal prostheses showed faster pain relief compared with trapeziectomy and ligament reconstruction and tendon interposition. Overall, there was a better strength in the trapeziometacarpal prosthesis group. A lack of information was found about the short- term functionality. The mobility recovers faster in the prosthesis group, although different scoring scales were used for measurement. We could confirm the faster pain relief in the prosthesis group and generally a faster recovery of strength and mobility. In the prosthesis group were more short-term complications. More studies are required to evaluate the short-term recovery of strength, the mobility, functionality and satisfaction.

Knee alignment in adolescents is correlated with participation in weight-bearing sports.

PURPOSE: Weight-bearing sports might influence the alignment of the lower extremities during growth. The relationship between participation in weight-bearing sports and the alignment of the lower extremities in adolescents has not been adequately studied yet. The aim of the study was to investigate whether sports participation during growth in early adolescence is correlated with the development of genu varum. METHODS: The design was a correlation study in which 1008 (564 boys, 444 girls) healthy adolescents (from 12 to 19 years of age) were recruited in secondary schools. The alignment of the knee was determined by measuring the intercondylar (IC) and intermalleolar (IM) distance using a specially designed instrument and an inside calliper. The degree of sports participation of the participants was determined by a questionnaire in which they were asked how many hours a week they participated in sports and for how many years in total. RESULTS: The results of this study revealed a significant correlation between participation in weight-bearing sports and genu varum in each of three different age groups, both for boys and girls. CONCLUSION: Our results show that there is an association between the alignment of the knee joint and participation in weight-bearing sports during early adolescence.

Safe zone for the posterior interosseous nerve with regard to the lateral and posterior approaches to the proximal radius.

PURPOSE: The posterior interosseous nerve (PIN) is at risk during the posterior and lateral approaches to the proximal radius. We aimed to define a safe zone for these approaches to avoid injury of the PIN and to evaluate their close and changing relationship to the nerve during forearm rotation. METHODS: The study collective consisted of 50 upper limbs. After performance of the lateral approach, the distance between the tip of the radial head and the PIN's exit point from the supinator (= distance 1) and the shortest interval between the nerve's exit to the radial margin of the ulna (= distance 2) were measured in maximum pronation and supination. Then, the dorsal approach was conducted and again distance 1 and the interval between the distal margin of the anconeus and the nerve's exit point (distance 2) were evaluated (pronation and supination). RESULTS: There were significantly shorter distances during supination in comparison to pronation. Regarding the lateral approach, distance 1 changed from a mean of 60.3 mm (supination) to 62.7 mm in pronation (p < 0.001). For the dorsal approach, distance 1 decreased significantly (p < 0.001) from 62.9 mm (pronation) to 60.2 mm (supination). CONCLUSION: Supination during the lateral and dorsal approaches to the proximal radius needs to be avoided to protect the PIN. Furthermore, the nerve appeared at an interval between 45 and 84.1 mm (lateral approach) and 47.5-93.8 mm (dorsal approach), respectively. Therefore, care must be taken at this height during extension of the approaches in a distal direction.

Indications for primary rotating-hinge total knee arthroplasty. Is there consensus?

The use of rotating-hinge systems in total knee arthroplasty is most often seen in revision setting where excessive bone loss, ligamentous instability and/ or extensor mechanism dysfunction may necessitate an increased level of component constraint. However, this implant type is also being increasingly used in the primary setting. The aim of this study is to review literature concerning the use of third generation rotating-hinge devices focusing on the indications for primary cases. Literature was searched for following search terms: total knee arthroplasty, primary indication, constraint, rotating hinge knee, knee prosthesis, hinged knee, total knee replacement. Additional papers were identified by screening references and similar articles. All papers dealing with first or second generation rotating-hinge implants and revision cases were discarded. After conducting a large literature search, we concluded that third generation rotating-hinge implants should be considered in limited indications in which ligamentous tibiofemoral instability is the core indication.

The fifty highest cited papers in anterior cruciate ligament injury.

INTRODUCTION: The anterior cruciate ligament (ACL) is one of the most common injured knee ligaments and at the same time, one of the most frequent injuries seen in the sport orthopaedic practice. Due to the clinical relevance of ACL injuries, numerous papers focussing on this topic including biomechanical-, basic science-, clinical- or animal studies, were published. The purpose of this study was to determine the most frequently cited scientific articles which address this subject, establish a ranking of the 50 highest cited papers and analyse them according to their characteristics. METHODS: The 50 highest cited articles related to Anterior Cruciate Ligament Injury were searched in Thomson ISI Web of Science® by the use of defined search terms. All types of scientific papers with reference to our topic were ranked according to the absolute number of citations and analyzed for the following characteristics: journal title, year of publication, number of citations, citation density, geographic origin, article type and level of evidence. RESULTS: The 50 highest cited articles had up to 1624 citations. The top ten papers on this topic were cited 600 times at least. Most papers were published in the American Journal of Sports Medicine. The publication years spanned from 1941 to 2007, with the 1990s and 2000s accounting for half of the articles (n = 25). Seven countries contributed to the top 50 list, with the USA having by far the most contribution (n = 40). The majority of articles could be attributed to the category "Clinical Science & Outcome". Most of them represent a high level of evidence. DISCUSSION: Scientific articles in the field of ACL injury are highly cited. The majority of these articles are clinical studies that have a high level of evidence. Although most of the articles were published between 1990 and 2007, the highest cited articles in absolute and relative numbers were published in the early 1980s. These articles contain well established scoring- or classification systems. CONCLUSION: The identification of important papers will help current clinicians and scientists to get an overview on past and current trends in that special field of ACL injury and provides a basis for both further discussion as well as future research.

Biomechanical Comparison of Intramedullary Versus Extramedullary Implants for Fixation of Simple Pertrochanteric Fractures.

OBJECTIVES: To evaluate the biomechanical performance of the intramedullary TFN-ADVANCED Proximal Femoral Nailing System (TFNA) versus the extramedullary Femoral Neck System (FNS) for fixation of simple pertrochanteric fractures in a human cadaveric model. METHODS: Ten human cadaveric femoral pairs were implanted pairwise with either TFNA or FNS. A simple pertrochanteric fracture OTA/AO 31-A1 was created and all specimens were biomechanically tested under progressively increasing cyclic loading until failure. Interfragmentary and bone-implant movements were monitored by motion tracking. RESULTS: Axial stiffness was comparable between TFNA and FNS, P = 0.34. Similarly, varus deformation, femoral head rotation around neck axis and implant migration remained without significant differences between TFNA and FNS after 3000 cycles (800 N peak load), P ≥ 0.10. However, cycles to 15-mm leg shortening were significantly higher for TFNA versus FNS, P < 0.01. CONCLUSIONS: From a biomechanical perspective, with its current design, FNS does not seem to be a valid alternative to TFNA for treatment of simple pertrochanteric fractures.

Advances in fixation strength of reorienting rectangular triple pelvic innominate osteotomies - A biomechanical investigation of two screw fixation techniques.

BACKGROUND: Reorientating pelvic osteotomies are performed to prevent femoral-acetabular impingement or degenerative arthritis. A Toennis-Kalchschmidt triple pelvis innominate osteotomy is used in symptomatic patients. This study aimed to investigate the biomechanical behaviour of two different acetabular screw configurations for triple pelvis innominate osteotomy osteosynthesis. METHODS: Two screw-orientation techniques in rectangular os ilium osteotomy were compared by osteotomising 12 artificial hemipelvises with triple pelvis innominate osteotomy protocol (fragment reorientation: 10.5° inclination and 10.0° anteversion) and randomising them in 2 groups (n = 6) for implantation with three 4.5 mm screws. Bidirectional group had a bidirectional screw orientation and Monoaxial group had a monoaxial direction of all three screws through iliac crest. All specimens were tested under progressively increasing cyclic loading until failure. Group-wise comparisons of acetabular cup medialisation, anteversion and inclination were evaluated via motion tracking at cycles 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, and 2500. Failure was defined as reaching 5° inclination or 5° anteversion. FINDINGS: Acetabular cup medialisation (p ≤ 0.026), anteversion (p ≤ 0.021) and inclination (p ≤ 0.039) all increased significantly during testing in both groups. There were no significant differences for the group-wise comparisons at the cycle points defined in the methods (p ≥ 0.182). No significant differences were detected between groups for cycles to failure and failure load (p = 0.873). INTERPRETATION: Bidirectional screw alignment does not lead to significant advantages compared to pure monoaxial if all three axial screws are evenly distributed over the osteotomy geometry. The triple pelvis innominate osteotomy is susceptible to changes in anteversion, inclination and medialisation under partial weight-bearing. Cautious rehabilitation protocols are recommended.

Proximal humeral fracture osteosynthesis in Belgium: a retrospective population-based epidemiologic study.

PURPOSE: Proximal humeral fractures (PHF) comprise approximately five percent of all fractures and this percentage will continue to increase due to the aging population with accompanying osteoporosis. Most PHF can be treated conservatively; however, in displaced fractures, surgical treatment is recommended. Retrospective analyses of large groups or even populations are important as they can contribute to the needs of the community. The aim of this study was to assess the epidemiology and management of PHF fixation in Belgium based on the most recently available data from the last 5 years. METHODS: The governmental organization National Institute of Health and Disability Insurance provided a population-based database with all PHF treated surgically or nonoperatively. This database was retrospectively assessed. The data included age, sex, region of residence, year and treatment strategy for every patient. Healthcare expenses were also provided. RESULTS: A total of 62,290 PHF were identified in Belgium between 2014 and 2018. The incidence was 111 per 100,000 persons/year. The highest incidence was observed in females and people older than 80 years. The average proportion of osteosynthesis was calculated at 21%. The Belgian government spent on average more than two million euros each year on PHF treatment. CONCLUSION: The overall incidence of PHF increased by 12% over the last 5 years. The majority were treated nonoperatively in Belgium.

Locking Plates With Computationally Enhanced Screw Trajectories Provide Superior Biomechanical Fixation Stability of Complex Proximal Humerus Fractures.

Joint-preserving surgical treatment of complex unstable proximal humerus fractures remains challenging, with high failure rates even following state-of-the-art locked plating. Enhancement of implants could help improve outcomes. By overcoming limitations of conventional biomechanical testing, finite element (FE) analysis enables design optimization but requires stringent validation. This study aimed to computationally enhance the design of an existing locking plate to provide superior fixation stability and evaluate the benefit experimentally in a matched-pair fashion. Further aims were the evaluation of instrumentation accuracy and its potential influence on the specimen-specific predictive ability of FE. Screw trajectories of an existing commercial plate were adjusted to reduce the predicted cyclic cut-out failure risk and define the enhanced (EH) implant design based on results of a previous parametric FE study using 19 left proximal humerus models (Set A). Superiority of EH versus the original (OG) design was tested using nine pairs of human proximal humeri (N = 18, Set B). Specimen-specific CT-based virtual preoperative planning defined osteotomies replicating a complex 3-part fracture and fixation with a locking plate using six screws. Bone specimens were prepared, osteotomized and instrumented according to the preoperative plan via a standardized procedure utilizing 3D-printed guides. Cut-out failure of OG and EH implant designs was compared in paired groups with both FE analysis and cyclic biomechanical testing. The computationally enhanced implant configuration achieved significantly more cycles to cut-out failure compared to the standard OG design (p < 0.01), confirming the significantly lower peri-implant bone strain predicted by FE for the EH versus OG groups (p < 0.001). The magnitude of instrumentation inaccuracies was small but had a significant effect on the predicted failure risk (p < 0.01). The sample-specific FE predictions strongly correlated with the experimental results (R2 = 0.70) when incorporating instrumentation inaccuracies. These findings demonstrate the power and validity of FE simulations in improving implant designs towards superior fixation stability of proximal humerus fractures. Computational optimization could be performed involving further implant features and help decrease failure rates. The results underline the importance of accurate surgical execution of implant fixations and the need for high consistency in validation studies.

Advanced CT visualization improves the accuracy of orthopaedic trauma surgeons and residents in classifying proximal humeral fractures: a feasibility study.

PURPOSE: Osteosynthesis of proximal humeral fractures remains challenging with high reported failure rates. Understanding the fracture type is mandatory in surgical treatment to achieve an optimal anatomical reduction. Therefore, a better classification ability resulting in improved understanding of the fracture pattern is important for preoperative planning. The purpose was to investigate the feasibility and added value of advanced visualization of segmented 3D computed tomography (CT) images in fracture classification. METHODS: Seventeen patients treated with either plate-screw-osteosynthesis or shoulder hemi-prosthesis between 2015 and 2019 were included. All preoperative CT scans were segmented to indicate every fracture fragment in a different color. Classification ability was tested in 21 orthopaedic residents and 12 shoulder surgeons. Both groups were asked to classify fractures using three different modalities (standard CT scan, 3D reconstruction model, and 3D segmented model) into three different classification systems (Neer, AO/OTA and LEGO). RESULTS: All participants were able to classify the fractures more accurately into all three classification systems after evaluating the segmented three-dimensional (3D) models compared to both 2D slice-wise evaluation and 3D reconstruction model. This finding was significant (p < 0.005) with an average success rate of 94%. The participants experienced significantly more difficulties classifying fractures according to the LEGO system than the other two classifications. CONCLUSION: Segmentation of CT scans added value to the proximal humeral fracture classification, since orthopaedic surgeons were able to classify fractures significantly better into the AO/OTA, Neer, and LEGO classification systems compared to both standard 2D slice-wise evaluation and 3D reconstruction model.

Angular stable locking in a novel intramedullary nail improves construct stability in a distal tibia fracture model.

INTRODUCTION: Intramedullary nails are frequently used for treatment of unstable distal tibia fractures. However, insufficient fixation of the distal fragment could result in delayed healing, malunion or nonunion. Recently, a novel concept for angular stable nailing was developed that maintains the principle of relative stability and introduces improvements expected to reduce nail toggling, screw migration and secondary loss of reduction. The aim of this study was to investigate the biomechanical competence of the novel angular stable intramedullary nail concept for treatment of unstable distal tibia fractures, compared to a conventional nail locking in a human cadaveric model under dynamic loading. MATERIALS AND METHODS: Ten pairs of fresh-frozen human cadaveric tibiae with a simulated AO/OTA 42-A3.1 fracture were assigned to 2 groups for reamed intramedullary nailing using either a conventional (non-angular stable) Expert Tibia Nail (ETN) with 3 distal screws or the novel Tibia Nail Advanced (TNA) system with 2 distal angular stable locking low-profile retaining screws. The specimens were biomechanically tested under conditions including initial quasi-static loading, followed by progressively increasing combined cyclic axial and torsional loading in internal rotation until failure of the bone-implant construct. Both tests were monitored by means of motion tracking. RESULTS: Initial nail toggling of the distal tibia fragment in varus and flexion under axial loading was lower for TNA compared to ETN, being significant in flexion, P = 0.91 and P = 0.03. After 5000 cycles, interfragmentary movements in terms of varus, flexion, internal rotation, axial displacement, and shear displacement at the fracture site were all lower for TNA compared to ETN, with flexion and shear displacement being significant, P = 0.14, P = 0.04, P = 0.25, P = 0.11 and P = 0.04, respectively. Cycles to failure until both interfragmentary 5° varus and 5° flexion were significantly higher for TNA compared to ETN, P = 0.04. CONCLUSION: From a biomechanical perspective, the novel angular stable intramedullary nail concept provides increased construct stability and maintains it over time while reducing the number of required locking screws without impeding the flexibility of the nail itself and resists better towards loss of reduction under dynamic loading, compared to conventional locking in intramedullary nailed unstable distal tibia fractures.

Percutaneous fixation of intraarticular joint-depression calcaneal fractures with different screw configurations - a biomechanical human cadaveric analysis.

PURPOSE: The aim of this study was to assess the biomechanical performance of different screw configurations for fixation of Sanders type II B joint-depression calcaneal fractures. METHODS: Fifteen human cadaveric lower limbs were amputated and Sanders II B fractures were simulated. The specimens were randomized to three groups for fixation with different screw configurations. The calcanei in Group 1 were treated with two parallel longitudinal screws, entering superiorly the Achilles tendon insertion, and two screws fixing the intraarticular posterior facet fracture line. In Group 2 two screws entered the tuberosity inferiorly to the Achilles tendon insertion and two transverse screws fixed the posterior facet. In Group 3 two screws were inserted along the bone axis, one transverse screw fixed the posterior facet and one oblique screw was inserted from the posteroplantar part of the tuberosity supporting the posterolateral part of the posterior facet. All specimens were biomechanically tested to failure under progressively increasing cyclic loading. RESULTS: Initial stiffness did not differ significantly between the groups, P = 0.152. Cycles to 2 mm plantar movement were significantly higher in both Group 1 (15,847 ± 5250) and Group 3 (13,323 ± 4363) compared with Group 2 (4875 ± 3480), P ≤ 0.048. No intraarticular displacement was observed in any group during testing. CONCLUSIONS: From a biomechanical perspective, posterior facet support by means of buttress or superiorly inserted longitudinal screws results in less plantar movement between the calcaneal tuberosity and the anterior fragments. Inferiorly inserted longitudinal screws are associated with bigger interfragmentary movements.

Osteosynthesis of proximal humeral fractures: a 1-year analysis of failure in a Belgian level-1 trauma centre.

PURPOSE: Proximal humeral fractures are the third most common fractures affecting the elderly. Angular stable osteosynthesis has become indispensable in the operative treatment. However, surgical fixation remains challenging. The aim of this retrospective study was to analyse the failure rate after osteosynthesis of proximal humeral fractures over a year in a level-1 trauma centre. Furthermore, parameters that are presumed to be related to osteosynthesis failure will be investigated and discussed. METHODS: After meeting the exclusion criteria, 134 patients were operatively treated with angular stable osteosynthesis between January 2017 and January 2018 at the University Hospitals of Leuven. RESULTS: Circa 16% of the proximal humeral osteosyntheses failed. Our study showed that the most significant parameter for osteosynthesis failure was smoking. The odds of failure were significantly lower if treated by a shoulder surgeon compared to another trauma surgeon in the plate and nail group combined. CONCLUSION: The management of proximal humeral fracture osteosynthesis remains a controversial subject. In this retrospective analysis, a failure rate of 15.7% was calculated. Smoking is a statistically significant parameter related to osteosynthesis failure. The subspecialty of the treating trauma surgeon affected the failure rate significantly. A lower failure rate was noted after osteosynthesis by a shoulder surgeon compared to another trauma surgeon.