Tibial tuberosity-trochlear groove distance is significantly decreased by medial closing wedge distal femoral osteotomy.

PURPOSE: While medial closing wedge distal femoral osteotomy (MCWDFO) has been used to address patella instability combined with valgus malalignment, its impact on patellofemoral parameters remains uncharted. Hence, this study seeks to establish a three-dimensional (3D) planning of MCWDFO and measure its effect on the tibial tubercle - trochlear groove distance (TTTG) through simulation and calculation. METHODS: MCWDFO with a stepwise increment of one-degree varisation (1°-15°) was performed on 3D surface models of 14 lower extremities with valgus malalignment and 24 lower extremities with neutral alignment of the lower limb, resulting in a total of 608 simulations. Anatomic landmarks were employed to measure hip-knee-ankle angle (HKA), TTTG, and femoral torsion for each simulation. A mathematical formula was adopted to calculate TTTG changes following MCWDFO, and subsequently the mean simulated and calculated TTTG values were compared. Following a standardised protocol, MCWDFO was performed without rotational changes. RESULTS: MCWDFO exhibited an almost linear reduction in TTTG, at a rate of approximately -1.05 ± 0.13 mm per 1° of varisation, demonstrating a strong negative correlation (R = -0.83; p < 0.001). Limb alignment did not exert an influence on TTTG change; however, it correlated with tibial plateau width. The mean difference between the simulated and calculated TTTG values amounted to 0.03 ± 0.03 mm per 1° varisation (p < 0.001). CONCLUSION: The TTTG distance is linearly reduced by 1.05 mm for every 1° of varisation within the varus correction range of 0°-15° during MCWDFO. Patients with combined valgus and patellar instability may benefit from MCWDFO due to frequently pathological TTTG. LEVEL OF EVIDENCE: Level III, descriptive laboratory study.

Preservation of the heart in ancient Egyptian mummies: A computed tomography investigation with focus on the myocardium.

The ancient Egyptians considered the heart to be the most important organ. The belief that the heart remained in the body is widespread in the archeological and paleopathological literature. The purpose of this study was to perform an overview of the preserved intrathoracic structures and thoracic and abdominal cavity filling, and to determine the prevalence and computed tomography (CT) characteristics of the myocardium in the preserved hearts of ancient Egyptian mummies. Whole-body CT examinations of 45 ancient Egyptian mummies (23 mummies from the Ägyptisches Museum und Papyrussammlung, Berlin, Germany, and 22 mummies from the Museo Egizio, Turin, Italy) were systematically assessed for preserved intrathoracic soft tissues including various anatomical components of the heart (pericardium, interventricular septum, four chambers, myocardium, valves). Additionally, evidence of evisceration and cavity filling was documented. In cases with identifiable myocardium, quantitative (measurements of thickness and density) and qualitative (description of the structure) assessment of the myocardial tissue was carried out. Heart structure was identified in 28 mummies (62%). In 33 mummies, CT findings demonstrated evisceration, with subsequent cavity filling in all but one case. Preserved myocardium was identified in nine mummies (five male, four female) as a mostly homogeneous, shrunken structure. The posterior wall of the myocardium had a mean maximum thickness of 3.6 mm (range 1.4-6.6 mm) and a mean minimum thickness of 1.0 mm (range 0.5-1.7 mm). The mean Hounsfield units (HU) of the myocardium at the posterior wall was 61 (range, 185-305). There was a strong correlation between the HU of the posterior wall of the myocardium and the mean HU of the muscles at the dorsal humerus (R = 0.77; p = 0.02). In two cases, there were postmortem changes in the myocardium, most probably due to insect infestation. To our knowledge, this is the first study to investigate the myocardium systematically on CT scans of ancient Egyptian mummies. Strong correlations between the densities of the myocardium and skeletal muscle indicated similar postmortem changes of the respective musculature during the mummification process within individual mummies. The distinct postmortem shrinking of the myocardium and the collapse of the left ventriclular cavity in several cases did not allow for paleopathological diagnoses such as myocardial scarring.

The infraacetabular screw versus the antegrade posterior column screw in acetabulum fractures with posterior column involvement: a biomechanical comparison.

INTRODUCTION: Traditionally, plate osteosynthesis of the anterior column combined with an antegrade posterior column screw is used for fixation of anterior column plus posterior hemitransverse (ACPHT) acetabulum fractures. Replacing the posterior column screw with an infraacetabular screw could improve the straightforwardness of acetabulum surgery, as it can be inserted using less invasive approaches, such as the AIP/Stoppa approach, which is a well-established standard approach. However, the biomechanical stability of a plate osteosynthesis combined with an infraacetabular screw instead of an antegrade posterior column screw is unknown. MATERIAL AND METHODS: Two osteosynthesis constructs were compared in a synthetic hemipelvis model with an ACPHT fracture: Suprapectineal plate + antegrade posterior column screw (APCS group) vs. suprapectineal plate + infraacetabular screw (IAS group). A single-leg stance test protocol with an additional passive muscle force and a cyclic loading of 32,000 cycles with a maximum effective load of 2400 N was applied. Interfragmentary motion and rotation of the three main fracture lines were measured. RESULTS: At the posterior hemitransverse fracture line, interfragmentary motion perpendicular to the fracture line (p < 0.001) and shear motion (p < 0.001) and at the high anterior column fracture line, interfragmentary motion longitudinal to the fracture line (p = 0.017) were significantly higher in the IAS group than in the APCS group. On the other hand, interfragmentary motion perpendicular (p = 0.004), longitudinal (p < 0.001) and horizontal to the fracture line (p = 0.004) and shear motion (p < 0.001) were significantly increased at the low anterior column fracture line in the APCS group compared to the IAS group. CONCLUSIONS: Replacing the antegrade posterior column screw with an infraacetabular screw is not recommendable as it results in an increased interfragmentary motion, especially at the posterior hemitransverse component of an ACPHT fracture.

Undersizing of the tibial component in Oxford unicompartmental knee arthroplasty (UKA) increases the risk of periprosthetic fractures.

INTRODUCTION: Tibial periprosthetic fractures (TPF) after unicompartmental knee arthroplasty (UKA) are a rare condition that affects about 1% of cases. Known risk factors include age, sex, body mass index (BMI), and bone density, as well as surgical technique and prosthesis design. The purpose of the study was to determine if undersizing of the tibial component in relation to the femoral component increases the risk of tibial periprosthetic fractures. MATERIAL AND METHODS: Over a 6-year-period 1542 patients with cemented (n = 363) and uncemented (n = 1179) medial UKA were retrospectively evaluated. Tibial periprosthetic fractures were identified and classified, and epidemiologic data were documented at follow-up. Undersizing was defined as a smaller tibial component compared to the femoral implant. The association of potential risk factors for TPF with the incidence of TPF was investigated with binominal logistic regression. RESULTS: Fourteen patients (0.9%) suffered from TPF at a median of 1 month after surgery. The mean follow-up period was 5.9 ± 1.7 years. Fractures were more common in cases with undersized tibial components [odds ratio (OR) 3.2, p < 0.05]. Furthermore, older age (OR 1.1, p < 0.05) and female sex (OR 6.5, p < 0.05) were identified as significant risk factors, while BMI (p = 0.8) and cemented implantation (p = 0.2) had no effect on fracture rate. Revision surgery included open reduction and internal fixation or conversion to total knee arthroplasty. CONCLUSIONS: Undersizing of implant sizes in UKA increases the risk for TPF especially in patients with small tibial implants. Therefore, mismatched implants should be avoided for UKA particularly when risk factors like obesity, older age, or female gender are present. Tibial periprosthetic fractures were successfully treated by open reduction and internal fixation or conversion to total knee arthroplasty.

Influence of different CCD angles on osseointegration and radiological changes after total hip arthroplasty of a triple wedge shape cementless femoral stem: a prospective cohort study.

PURPOSE: The purpose of this study was to evaluate the osseointegration and radiological outcomes in patients after total hip arthroplasty, hypothesizing different load patterns with one cementless stem design and different CCD angles (CLS Spotorno femoral stem 125° vs 135°). METHODS: All cases of degenerative hip osteoarthritis fulfilling strict inclusion criteria were treated with cementless hip arthroplasty between 2008 and 2017. Ninety-two out of one hundred six cases were clinically and radiologically examined three and 12 months after implantation. Two groups with each 46 patients were rendered prospectively and compared in clinical (Harris Hip Score) and radiological outcome. RESULTS: At final follow-up, no significant difference regarding Harris Hip Score was detected between the two groups (mean 99.2 ± 3.7 vs. 99.3 ± 2.5; p = 0.73). Cortical hypertrophy was found in none of the patients. Stress shielding was seen in a total of 52 hips (n = 27 vs. n = 25; 57% of the 92 hips). No significant difference regarding stress shielding was detected when comparing both groups (p = 0.67). Significant bone density loss was detected in Gruen zone one and two in the 125° group. The 135° group showed significant radiolucency in Gruen zone seven. No overall radiological loosening or subsidence of the femoral component was observed. CONCLUSION: According to our results, the use of a femoral component with a 125° CCD angle versus a 135° CCD did not result in a different osseointegration and load transfer with a clinically relevant significance.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study.

BACKGROUND: Septic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study. MATERIALS AND METHODS: Osteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation. RESULTS: The cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture. CONCLUSIONS: Our findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness. LEVEL OF EVIDENCE: Level 2 Trial registration DRKS00014657 (date of registration: 2018/04/26).

Three internal fixation methods for Danis-Weber-B distal fibular fractures: A biomechanical comparison in an osteoporotic fibula model.

A common agreement for the surgical treatment of osteoporotic ankle fractures has not been defined yet although locking plates are preferred for fractures with poor bone quality. This study aims to evaluate the mechanical stability of locked and conventional plates on osteoporotic Danis-Weber-B-fibula fracture models. Fractured custom-made osteoporotic fibulae were treated with neutralization plate plus lag screw, locking plate plus lag screw, or a standalone locking plate. Load until failure was applied mimicking single-leg stance. Stiffness, failureload, and interfragmentary movements were investigated. Stiffness, failureload and axial fragment movement showed no significant differences among groups. Shear movements and fragment rotation around the shaft of the neutralization plate were on average twice as high as those of the locking plates. Although no superiority was shown for overall mechanical performance, the locking plate groups exhibited higher shear and rotational stability than the neutralization plate.

Robot-assisted training after proximal humeral fracture: A randomised controlled multicentre intervention trial.

OBJECTIVE: To examine whether robotic-assisted training as a supplement to usual therapy is safe, acceptable and improves function and patient reported outcome after proximal humeral fractures (PHF). DESIGN: Multicentre, assessor-blinded, randomised controlled prospective trial. SETTING: Three different rehabilitation hospitals in Germany. SUBJECTS: In total 928 PHF patients between 35 and 70 years were screened. Forty-eight participants were included in the study (intervention group n = 23; control group n = 25). INTERVENTION: The control group received usual occupational and physiotherapy over three weeks, and the intervention group received additional 12 robot-assisted training sessions at the ARMEO®-Spring. MAIN MEASURES: Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH), the Wolf Motor Function Test-Orthopaedic, active range of motion and grip strength were determined before and after intervention period. The DASH was additionally obtained postal 6 and 13 months following surgery. RESULTS: The mean age of participants was 55 ± 10 years and was similar in both groups (p > 0.05). The change in DASH as the primary endpoint in the intervention group after intervention was -15 (CI = 8-22), at follow-up six month -7 (CI = -2 to 16) at follow up 13 month -9 (CI = 1-16); in control group -14 (CI = 11-18), at follow-up six month -13 (CI = 7-19) at follow up 13 month -6 (CI = -3 to 14). No difference in the change was found between groups (p > 0.05). None of the follow-up time points demonstrated an additional benefit of the robotic therapy. CONCLUSION: The additional robot-assisted therapy was safe, acceptable but showed no improvement in functional shoulder outcome compared to usual therapy only.

E-vapor aerosols do not compromise bone integrity relative to cigarette smoke after 6-month inhalation in an ApoE-/- mouse model.

Cigarette smoke (CS) exposure is one of the leading risk factors for human health. Nicotine-containing inhalable products, such as e-cigarettes, can effectively support tobacco harm reduction approaches. However, there are limited comparative data on the effects of the aerosols generated from electronic vapor products (e-vapor) and CS on bone. Here, we report the effects of e-vapor aerosols and CS on bone morphology, structure, and strength in a 6-month inhalation study. Eight-week-old ApoE-/- mice were exposed to aerosols from three different e-vapor formulations-CARRIER (propylene glycol and vegetable glycerol), BASE (CARRIER and nicotine), TEST (BASE and flavor)-to CS from 3R4F reference cigarettes at matched nicotine concentrations (35 µg/L) or to fresh air (Sham) (N = 10 per group). Tibiae were analyzed for bone morphology by µCT imaging, biomechanics by three-point bending, and by histological analysis. CS inhalation caused a significant decrease in cortical and total bone volume fraction and bone density relative to e-vapor aerosols. Additionally, CS exposure caused a decrease in ultimate load and stiffness. In contrast, bone structural and biomechanical parameters were not significantly affected by e-vapor aerosol or Sham exposure. At the dissection time point, there was no significant difference in body weight or tibia bone weight or length among the groups. Histological findings revealed microcracks in cortical bone areas among all exposed groups compared to Sham control. In conclusion, because of the bone-preserving effect of e-vapor aerosols relative to CS exposure, e-vapor products could potentially constitute less harmful alternatives to cigarettes in situations in which bone health is of importance.

The effect of coronal splits on the structural stability of bi-condylar tibial plateau fractures: a biomechanical investigation.

INTRODUCTION: Surgical treatment of bi-condylar tibial plateau fractures is still challenging due to the complexity of the fracture and the difficult surgical approach. Coronal fracture lines are associated with a high risk of fixation failure. However, previous biomechanical studies and fracture classifications have disregarded coronal fracture lines. MATERIALS AND METHODS: This study aimed to develop a clinically relevant fracture model (Fracture C) and compare its mechanical behavior with the traditional Horwitz model (Fracture H). Twelve samples of fourth-generation tibia Sawbones were utilized to realize two fracture models with (Fracture C) or without (Fracture H) a coronal fracture line and both fixed with lateral locking plates. Loading of the tibial plateau was introduced through artificial femur condyles to cyclically load the fracture constructs until failure. Stiffness, fracture gap movements, failure loads as well as relative displacements and rotations of fracture fragments were measured. RESULTS: The presence of a coronal fracture line reduced fracture construct stiffness by 43% (p = 0.013) and decreased the failure load by 38% from 593 ± 159 to 368 ± 63 N (p = 0.016). Largest displacements were observed at the medial aspect between the tibial plateau and the tibial shaft in the longitudinal direction. Again, the presence of the coronal fracture line reduced the stability of the fragments and created increased joint incongruities. CONCLUSIONS: Coronal articular fracture lines substantially affect the mechanical response of tibia implant structures specifically on the medial side. With this in mind, utilizing a clinically relevant fracture model for biomechanical evaluations regarding bi-condylar tibial plateau fractures is strongly recommended.

Biomechanics of Osteoporotic Fracture Fixation.

PURPOSE OF REVIEW: Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e., pelvis, hip, ankle, and peri-implant fractures. RECENT FINDINGS: Elderly individuals benefit immensely from immediate mobilization after fracture and thus require stable fracture fixation that allows immediate post-operative weight-bearing. However, osteoporotic bone has decreased holding capacity for metallic implants and is thus associated with a considerable fracture fixation failure rate both short term and long term. Modern implant technologies with dedicated modifications provide sufficient mechanical stability to allow immediate weight-bearing for elderly individuals. Depending on fracture location and fracture severity, various options are available to reinforce or augment standard fracture fixation systems. Correct application of the basic principles of fracture fixation and the use of modern implant technologies enables mechanically stable fracture fixation that allows early weight-bearing and results in timely fracture healing even in patients with osteoporosis.

Inter-rater reliability, sensitivity to change and responsiveness of the orthopaedic Wolf-Motor-Function-Test as functional capacity measure before and after rehabilitation in patients with proximal humeral fractures.

BACKGROUND: The incidence of proximal humeral fractures (PHF) increased by more than 30% over the last decade, which is accompanied by an increased number of operations. However, the evidence on operative vs. non-operative treatment and post-operative treatments is limited and mostly based on expert opinion. It is mandatory to objectively assess functional capacity to compare different treatments. Clinical tools should be valid, reliable and sensitive to change assessing functional capacity after PHFs. This study aimed to analyse inter-rater reliability of the videotaped Wolf-Motor-Function-Test-Orthopaedic (WMFT-O) and the association between the clinical WMFT-O and the Disability of the Arm, Shoulder and Hand (DASH) and to determine the sensitivity to change of the WMFT-O and the DASH to measure functional capacity before and after rehabilitation in PHF patients. METHODS: Fifty-six patients (61.7 ± 14.7 years) after surgical treatment of PHF were assessed using the WMFT-O at two different time points. To determine inter-rater reliability, the videotaped WMFT-O was evaluated through three blinded raters. Inter-rater agreement was determined by Fleiss' Kappa statistics. Pearson correlation coefficients were calculated to assess the association between the clinical WMFT-O and the video rating as well as the DASH. Sensitivity to change and responsiveness were analysed for the WMFT-O and the DASH in a subsample of forty patients (53.8 ± 1.4 years) who were assessed before and after a three week robotic-assisted training intervention. RESULTS: Inter-rater agreement was indicated by Fleiss' Kappa values ranging from 0.33-0.66 for functional capacity and from 0.27-0.54 for quality of movement. The correlation between the clinical WMFT-O and the video rating was higher than 0.77. The correlation between the clinical WMFT-O and the DASH was weak. Sensitivity to change was high for the WMFT-O and the DASH and responsiveness was given. In comparison to the DASH, the sensitivity to change of the WMFT-O was higher. CONCLUSION: The overall results indicate that the WMFT-O is a reliable, sensitive and responsive instrument to measure more objectively functional change over time in rehabilitation after PHF. Furthermore, it has been shown that video assessment is eligible for studies to ensure a full blinding of raters. TRIAL REGISTRATION: Clinicaltrials.gov, NCT03100201 . Registered on 28 March 2017. The trial was retrospectively registered.

Opening-wedge osteotomies of the distal femur: minor advantages for a biplanar compared to a uniplanar technique.

PURPOSE: Valgus malalignment of the distal femur may be treated with corrective osteotomy. The purpose of this study was to compare the primary stability of a lateral opening-wedge osteotomy (LOWO) using a uniplanar compared to a biplanar technique. A study was carried out to test both surgeries, with both an intact medial cortex and with a deliberate attached cut of the medial cortex simulating a fracture. The primary hypothesis was that the biplanar technique provides higher axial and torsional stiffness. It was further hypothesized that the mechanical superiority of the biplanar technique would not be affected in the case of breakage of the far medial cortex. METHODS: A LOWO was performed in ten synthetic femora (#3406 left large Femur, 4th Generation, Sawbones, Malmö, Sweden) using a lateral angle stable locking plate (NCB© Distal Femur Plate, Zimmer Biomet, Warsaw, USA). A uniplanar osteotomy was performed in five femora, and a biplanar osteotomy was performed in five femora. The femora were tested for axial and torsional loads using a servo-hydraulic testing machine (Instron 8874, Instron Structural Testing GmbH, High Wycombe, UK). RESULTS: Axial stiffness decreased significantly (p = 0.001) in both groups (20% in the uniplanar group and 28 % in the biplanar group) by cutting the medial cortex. The type of osteotomy had no significant effect. A slightly lower but not statistically significant axial stiffness was seen in the biplanar group both for intact and broken medial cortices. Internal torsional stiffness dropped by more than 30% for the uniplanar group and almost 24% for the biplanar group when the cortex was cut (p < 0.001). No significant change concerning internal torsional stiffness was found between the two groups. External torsional stiffness decreased by 32% for the uniplanar group and 4% for the biplanar group after the cortical cut (p = 0.029). No significant change concerning external torsional stiffness was found between the groups, but the biplanar group showed a tendency towards higher values of external torsional stiffness. CONCLUSIONS: The axial and torsional stiffness of the implant-bone construct were not significantly affected by the type of osteotomy performed. Biplanar osteotomy tended to increase external torsional stiffness. In cases of fracture of the medial cortex, biplanar osteotomy significantly reduced the external rotation at the osteotomy and showed a significantly increased external torsional stiffness.

The pararectus approach for internal fixation of acetabular fractures involving the anterior column: evaluating the functional outcome.

INTRODUCTION: Aim of this retrospective analysis of prospectively collected data was to evaluate the functional mid-term outcome two years after open reduction and internal fixation of acetabular fractures involving the anterior column with affection of the quadrilateral plate using the pararectus approach on a large cohort. METHOD: Fifty-two patients (12 female, 40 male) with a median age of 55 (range 18-90) years and displaced acetabular fractures involving the anterior column were surgically treated in a single level I trauma centre between July 2012 and February 2016 using the pararectus approach. Thirty-four patients (8 female and 26 male) with a median age of 58 (range 20-85) years were available for complete clinical follow-up at regular intervals, finally 24 months post-operatively. Functional outcome was evaluated according to modified Merle d'Aubigné score, Lower Extremity Functional Scale, WOMAC, and SF-36. RESULTS: Range of time between trauma and surgical treatment was three (range 0-19) days. Operation time was 140 (range 60-240) minutes, and duration of hospital treatment was 19 (range 7-38) days. Functional results in 34 patients available for final follow-up demonstrated 68 points (median; range 39-80) according to the Lower Extremity Functional Scale, 6% according to the WOMAC (mean; SD ± 14.5%), and 69% (mean; SD ± 20.1%) according to the SF-36. The modified Merle d'Aubigné score was excellent in 22 patients, good in eight patients, and fair in four patients. DISCUSSION/CONCLUSION: Based on the good to excellent functional mid-term follow-up results of this study, the pararectus approach can be recommended as sufficient alternative single access to address displaced acetabular fractures involving the anterior column, independent of patients' age.

Treatment of infection following intramedullary nailing of tibial shaft fractures-results of the ORS/ISFR expert group survey.

OBJECTIVE: The lack of universally accepted treatment principles and protocols to manage infected intramedullary (IM) nails following tibial fractures continues to challenge us, eliciting a demand for clear guidelines. Our response to this problem was to create an ORS/ISFR taskforce to identify potential solutions and trends based on published evidence and practices globally. MATERIALS AND METHODS: A questionnaire of reported treatment methods was created based on a published meta-analysis on the topic. Treatment methods were divided in two groups: A (retained nail) and B (nail removed). Experts scored the questionnaire items on a scale of 1-4 twice, before and after revealing the success rates for each stage of infection. Inter- and intra-observer variability analysis among experts' personal scores and between experts' scores was performed. An agreement mean and correlation degree between experts' scores was calculated. Finally, a success rate report between groups was performed. RESULTS: Experts underestimated success rate of an individual treatment method compared to published data. The mean difference between experts' scores and published results was + 26.3 ± 46 percentage points. Inter-observer agreement mean was poor (< 0.2) for both rounds. Intra-observer agreement mean across different treatment methods showed a wide variability (18.3 to 64.8%). Experts agree more with published results for nail removal on stage 2 and 3 infections. CONCLUSIONS: Experts' and published data strongly agree to retain the implant for stage 1 infections. A more aggressive approach (nail removal) favoured for infection stages 2 and 3. However, literature supports both treatment strategies. EVIDENCE: Clinical Question.

Characterization of an artificial skull cap for cranio-maxillofacial surgery training.

Cranial grafts are favored to reconstruct skeletal defects because of their reduced resorption and their histocompatibility. Training possibilities for novice surgeons include the "learning by doing" on the patient, specimens or simulators. Although the acceptance of simulators is growing, the major drawback is the lack of validated bone models. The aim of this study was to create and validate a realistic skull cap model and to show superiority compared to a commercially available skull model. Characteristic forces during machinery procedures were recorded and thickness parameters from the bony layers were obtained. The thickness values of the bone layers of the developed parietal bone were comparable to the human ones. Differences between drilling and sawing forces of human and artificial bones were not detected using statistical analysis. In contrast the parameters of the commercially available skull model were significantly different. However, as a result, a model-based simulator for tabula externa graft lift training, consisting of a brain, skull bone cap and covering soft tissues was created. This simulator enables the training of all procedural steps of a "split thickness graft lift". In conclusion, an artificial skull cap suitable for parietal graft lift training was manufactured and validated against human parietal bones.

Characterization of polyurethane-based synthetic vertebrae for spinal cement augmentation training.

Vertebral augmentation techniques are used to stabilize impacted vertebrae. To minimize intraoperative risks, a solid education of surgeons is desirable. Thus, to improve education of surgeons as well as patient safety, the development of a high-fidelity simulator for the surgical training of cement augmentation techniques was initiated. The integrated synthetic vertebrae should be able to provide realistic haptics during all procedural steps. Synthetic vertebrae were developed, tested and validated with reference to human vertebrae. As a further reference, commercially available vertebrae surrogates for orthopedic testing were investigated. To validate the new synthetic vertebrae, characteristic mechanical parameters for tool insertion, balloon dilation pressure and volume were analyzed. Fluoroscopy images were taken to evaluate the bone cement distribution. Based on the measurement results, one type of synthetic vertebrae was able to reflect the characteristic parameters in comparison to human vertebrae. The different tool insertion forces (19.7 ± 4.1, 13.1 ± 0.9 N, 1.5 ± 0.2 N) of the human reference were reflected by one bone surrogate (11.9 ± 9.8, 24.3 ± 3.9 N, 2.4 ± 1.0 N, respectively). The balloon dilation pressure (13.0 ± 2.4 bar), volume (2.3 ± 1.5 ml) of the synthetic vertebrae were in good accordance with the human reference (10.7 ± 3.4 bar, 3.1 ± 1.1 ml). Cement application forces were also in good accordance whereas the cement distribution couldn't be reproduced accurately. Synthetic vertebrae were developed that delivered authentic haptics during transpedicular instrument insertion, balloon tamp dilation and bone cement application. The validated vertebra model will be used within a hybrid simulator for minimally invasive spine surgery to educate and train surgeons.

Inter-rater and intra-rater reliability of an adapted Wolf motor function test for older patients with shoulder injuries.

BACKGROUND AND OBJECTIVE: The Wolf motor function test (WMFT) evaluates the upper extremity performance of patients with neurological disorders and traumatic brain injuries by assessing time and functional capacity. It was later modified to also measure the quality of the performed movements. This study aimed to adapt the WMFT for patients with shoulder injuries and to evaluate the inter-rater and intra-rater reliability of this adapted version. SUBJECTS AND METHODS: A total of 20 individuals with a median age of 80.5 years were assessed using a test-retest design after surgical or conservative treatment of shoulder injuries. Two raters rated performance to determine inter-rater reliability. One rater rated the performance again to determine intra-rater reliability. Both inter-rater and intra-rater agreement were determined by weighted Cohen's kappa statistics with corresponding confidence intervals. Cronbach's alpha was calculated to determine internal consistency. RESULTS: The inter-rater Cohen's kappa values ranged from 0.84-1.00 for functional capacity and from 0.79-1.00 for quality of movement. For intra-rater reliability the Cohen's kappa ranged from 0.71-1.00. Cronbach's alpha was >0.94 for functional capacity and >0.96 for quality of movement. CONCLUSION: The adapted version of the WMFT shows high intra-rater and inter-rater reliability for patients with shoulder injuries.

Single versus double row suture anchor fixation for greater tuberosity fractures - a biomechanical study.

BACKGROUND: Fractures of the humeral greater tuberosity (GT) are a frequent injury progressively treated with arthroscopic suture anchor repair. Yet, no biomechanical study has been performed comparing fixation strength of arthroscopic single- (SR) vs. double row (DR) fixation. METHODS: Standardized fractures of the greater tuberosity were created in 12 fresh frozen proximal humeri. After random assignation to the SR or DR group the fixed humeri were tested applying cyclic loading to the supraspinatus and infraspinatus tendon. Load to failure and fragment displacement were assessed by means of an electrodynamic material testing machine using an optical tracking system. RESULTS: Load to failure values were higher in the DR group (649 N; ±176) than in the SR group (490 N; ±145) however without statistical significance (p = .12). In greater tuberosity displacement of 3-5 mm surgical treatment is recommended. The fixing constructs in this study did not reach displacement landmarks of 3 or 5 mm before construct failure as shown in previous studies. Thus the applied traction force (N) at 1 mm displacement was analyzed. In the SR group the load at 1 mm displacement was 277 N; ±46 compared to 260 N; ±62 in the DR group (p = .65). CONCLUSION: The results suggest that both techniques are viable options for refixation of greater tuberosity fractures. LEVEL OF EVIDENCE: Laboratory study.

Biomechanical comparison of anatomical plating systems for comminuted distal humeral fractures.

PURPOSE: Six different mono-axial and poly-axial distal humeral plating systems with an anatomical plate design were compared. The aim of the biomechanical tests was to examine differences regarding system stiffness, median fatigue limit, and failure mechanisms. METHODS: Different configurations of two double plate fixation systems by two manufacturers for the treatment of complex distal humeral fractures (AO/OTA type C2.3) were biomechanically tested in a physiologically relevant setup. RESULTS: The 180° Stryker configuration presented itself as the system with the highest stiffness, being significantly stiffer (p < 0.001) than every system other than the poly-axial 180° aap system (p = 0.378). For the median fatigue limit the 180° Stryker and poly-axial aap systems were ranked first and second. The failure mechanism for all 90° systems was a fatigue breakage of the posterolateral plate. The 180° aap systems demonstrated breakage of the most distal screws of the lateral plate. The 180° Stryker system demonstrated screw breakage on both the medial and lateral plates. DISCUSSION: Breakage of the posterolateral plate as a failure mechanism for the 90° systems was expected. The 180° systems demonstrated a higher stiffness compared to the 90° constructs for the axial loading. In conclusion, both poly-axial anatomical plating systems provide sufficient stability in this scenario, and the 180° configurations demonstrated superior stiffness.