IntroductionBiomechanical studies have proved that locking plates have better primary stability besides versatility regarding fracture pattern while reducing bone contact and bridging the gap, whereas conventional nonlocking plates (plus lag screw) depend on bone-plate compression. The clinical benefit of locking plates over nonlocking plates remains unanswered, however. Therefore, this retrospective cohort study was set up to test the hypothesis that the use of locking plates for unstable ankle fractures will result in fewer re-displacements, superior bony healing, and functional and clinical outcomes better than observed in the nonlocking cohort.MethodsBimalleolar ankle fractures (AO 44-B2) without syndesmotic injury treated with either a locking or a nonlocking plate were included. Groups were compared for complications, bone healing, secondary dislocation, progressions of osteoarthritis, and clinical outcome using patient-reported outcome measures.ResultsData revealed no clinical outcome differences (Olerud-Molander Ankle Score: nonlocking 88.2 ± 14.4, locking 88.8 ± 12.3, P = .69, robust two 1-sided test for equality (RTOST): P = .03; American Orthopaedic Foot and Ankle Score: nonlocking 91.2 ± 12.9, locking 91.8 ± 11.3, P = .96, RTOST: P = .04). Nevertheless, a significant postoperative progression of osteoarthritis was detected in both groups (P = .04). This was independent of implant (P = .16). Although difference was not significant, locking plates were preferred in older (P = .78) and sicker patients (P = .63) and in cases with severer osteoarthritis (P = .16), and were associated with a higher complication rate (P = .42) and secondary dislocation (nonlocking 9.4%, locking 18.2%; P = .42). Re-displacement, however, was not a compelling reason for revision.ConclusionsThe present study shows statistically significant equality of both types of implants. Contrary to our expectation, locking plates seemed to be associated with a higher risk for re-displacement. Overall, the use of either locking or nonlocking plates for unstable AO 44-B2 fractures is safe and successful despite significant progression of osteoarthritis.Level of Evidence:III, Retrospective observational cohort study.

Objectives Helical plating is an established alternative to straight plating for humeral shaft fractures in order to prevent iatrogenic radial nerve damage. However, a previous biomechanical investigation indicated differences in fracture healing for helical plating due to a potential shift of interfragmentary movements compared to straight plating. Therefore, fracture healing simulations were performed to assess any differences in bone healing of helical vs. straight plating. Methods A systematic workflow for fracture healing analytics was created, covering essential steps of bone modelling, implant modelling, finite element modelling, fracture healing simulation and result analysis. Computational humerus models with an AO12C2 fracture and straight and helical osteosynthesis were created. An established fracture healing model was used to simulate callus formation over 112 days under physiological loading. The predicted tissue differentiation and interfragmentary movement (IFM) was tracked over the entire simulated healing course. Results Helical plating resulted in larger interfragmentary movements for compression and shear components, and in a greater proportion of near and far cortical movement. Vascularization and tissue formation were deferred, but cortical bridging was achieved. Conclusions Helical plating resulted in slightly deferred bone healing due to larger interfragmentary shear movements. Considering the advantage of helical plating in clinical context, a slightly deferred bone healing is justifiable.

OBJECTIVES:This study aimed to determine the impact of physiological loading and boundary conditions on the biomechanical performance of a plating system for femoral shaft osteosynthesis via axial implant system testing (IST). Specifically, the effects of rotational load boundary conditions and realistic gait-based load patterns were evaluated to understand their influence on the biomechanical response and failure modes of the implant system. METHODS:Two test configurations - Fix-Free, featuring a rotational joint, and Fix-Fix, with fixed support at both ends - were subjected to static and cyclic loading. Cyclic testing incorporated sinusoidal and gait-based load patterns, reflecting the physiological axial joint load during walking. In total, 30 test samples (n=30), employed by a bone surrogate and the plate-screw system in bridge-plating state, were tested via axial IST. RESULTS:The Fix-Free configuration exhibited significantly lower axial stiffness and load capacity reductions of 60.8 % compared to Fix-Fix in static testing. Under cyclic gait-based loading, both setups experienced progressive screw-plate interface failures, with earlier degradation observed in Fix-Free. CONCLUSIONS:Findings indicate a strong impact of physiological load patterns and boundary conditions. The results support the need for standards and guidelines for biomechanical testing of osteosynthetic plating systems via IST with universal physiological boundaries.

Objectives: A previously published biomechanical study of axial cyclic testing on a locking-type plating system presented several failure types of the screw-plate interfaces (SPI). It was assumed that increasing micromotions of SPIs result consequently in initial failure of SPIs during cyclic loading. In conclusion, measurements of SPIs via digital image correlation (DIC) were suggested to detect potential micromotions. Methods: DIC measurements were performed using the ARAMIS Adjustable 3D measurement system to track the surface of the screw-head and bone plate during cyclic testing to determine potential micromotions. The micromotion is thereby described as the change in distance of the screw-head center to a reference point on the bone plate, providing information about the quality of interlocking of the related SPI during cyclic loading. Micromotion analysis was performed on the fracture-adjacent SPIs of the implant system, that were considered as the most relevant interfaces. Results: Micromotion could be detected for both facture-adjacent SPIs in all test samples with increasing magnitude during cyclic testing, resulting in micromotions up to 587 micrometer for the proximal and 321 micrometer for the distal fracture-adjacent SPI after 50k load cycles. The strongest increase in micromotion could thereby be detected within early stages of cyclic loading. Conclusions: The approach to determine micromotions of SPIs during axial cyclic loading was successful, indicating a reduction of the quality of interlocking of SPIs as micromotions increase during cyclic loading of the tested locking-type implant system. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The research project was funded by the Federal Ministry for Economic Affairs and Energy and by the Central Innovation Program for small and me-dium sized enterprises of Germany. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript

Objectives Helical plating is an established method for treating proximal humeral shaft fractures, mitigating the risk of iatrogenic radial nerve damage. However, biomechanical test data on helical plates under physiological load condition is limited. Hence, the aim of this study was to compare the biomechanical performance of helical and straight PHILOS (R) Long plates in AO12C2 fractures using static and cyclic implant system testing.Methods Helical and straight PHILOS (R) Long plates on artificial bone substitutes were tested under physiological axial static (n=6) and cyclic loading (n=12). The axial construct stiffness was the main parameter for comparing the biomechanical performance of the two groups. Mimicking a clinical scenario, the helical deformation was performed consecutively by an experienced surgeon using iron bending tools. The torsional angle was determined computationally from 3D-scanning models afterwards.Results Helical plating resulted in a significantly reduced axial construct stiffness in all test scenarios compared to conventional straight plating (static testing: p=0.012; cyclic testing: p <= 0.010). No failure occurred within the range of physiological loading in both groups.Conclusions Helical plating favors multidimensional deformation of the test sample in lateral-ventral direction under axial loading, resulting in a reduced axial construct stiffness and in an increased interfragmentary movement. No biomechanical failure is to be expected within physiological load boundaries.

Abstract Proximal humeral shaft fractures can be treated with helically deformed bone plates to reduce the risk of iatrogenic nerve lesion. Controversially to this common surgical technique that was first established in 1999, no biomechanical investigation on humeral helical plating is recorded by other reviews, which focus on proximal fractures exclusively. Does an additional scope for shaft fractures reveal findings of helical testing? The present systematic literature review was performed based on guidelines by Kitchenham et al. to systematically search and synthesize literature regarding biomechanical testing of osteosynthetic systems for proximal humeral shaft fractures. Therefore, a systematic approach to search and screen literature was defined beforehand and applied on the findings of the database PubMed®. Synthesized information of the included literature was categorized, summarized and analyzed via descriptive statistics. Out of 192 findings, 22 publications were included for qualitative synthesis. A wide range of different test methods was identified, leading to a suboptimal comparability of specific results between studies. Overall, 54 biomechanical test scenarios were identified and compared. Physiological based boundary conditions (PB-BC) were referenced in 7 publications only. One study of testing straight and helical dynamic compression plates without PB-BCs was identified, showing significant differences under compressional loading. The absence of test standards of specific fields like humeral fractures lead to a high variance in biomechanical testing of osteosynthetic locking plates for proximal humeral shaft fractures. Physiological approaches offer realistic test scenarios but need to be uniformed for enhanced comparability between studies. The impact of helically deformed locking plates under PB-BC was not identified in literature.

Background: Articular cartilage has an exceptionally poor capacity for healing, but Autologous Matrix Induced Chondrogenesis is a procedure with a substantial body of literature that demonstrates its performance in chondral and osteochondral repair. However, data concerning dynamic postural stability after cartilage repair procedures is lacking. Objective: Therefore, the present study was designed to assess postural stability following cartilage repair in the knee. Methods: 20 adults had undergone Autologous Matrix Induced Chondrogenesis for the treatment of full-thickness cartilage defects, with minimum 36 months of follow-up. Clinical outcomes were evaluated by patient reported outcome measures while dynamic postural stability was assessed using the star excursion balance test. The untreated, contralateral limbs served as controls. Results: At a mean follow-up of 43 months, patients reported a Visual Analog Score for pain of 1.6±2.2, a mean Lysholm score of 78.5±17.9 and a mean Knee Osteoarthritis Outcome Score of 143.3±16.1. The star excursion balance test showed no significant difference between limbs. Conclusion: With no difference in dynamic postural stability, our results indicate that this treatment provides a positive clinical outcome, with no deficits in postural stability when compared to the contralateral, untreated leg.

Abstract Guided growth by temporary hemiepiphysiodesis (HEPD) is established for the alignment of lower limb angular deformities. This retrospective cohort study was designed to assess the effect of HEPD in idiopathic coronal plane deformities around the knee and on the frontal knee joint line orientation, and to test the frontal knee joint line as predictive means for recurrence. Fourty-four patients (78 deformities: valgus n = 64, varus n = 14) were enrolled in the retrospective observational study. Mechanical axis deviation, mechanical lateral distal femoral angle, and mechanical medial proximal tibial angle were assessed prior to surgery and during follow-up. The facultative frontal knee joint line angle (FKJLA) was used as predictive tool. Cases of remaining growth potential (n = 45/78) after implant removal were followed to assess rebound deformity. Pre-operative angles of the mechanical axis were corrected average 9.0 months after HEPD. Pre-operative assessment of the frontal knee joint line revealed a mean of 3.9° in valgus, and –1.0° in varus deformities. At time of complete deformity correction, mean FKJLA was –0.2° in valgus, and –0.8° in varus deformities. Mean shift of FKJLA was significantly higher after singleHEPD compared to combiHEPD (P < .001). Patients having an unphysiological FKJLA (>/<0°–3°) after correction of mechanical axis had a significantly higher risk of rebound deformity (P = .01). Regression analysis showed a 60.5% higher risk of rebound deformity per each degree deviating from the FKJLA physiological range. Age, gender, or body mass index had no impact. Temporary HEPD offers great potential for the correction of the mechanical axis and the frontal knee joint line. An unphysiological change of the frontal knee joint line is associated with a high risk of recurrent angular deformities. CombiHEPD instead of singleHEPD seems to be safer to prevent detrimental frontal knee joint line shift. Level of Evidence: Retrospective comparative therapeutic study, Level III.

Cancer proteomics provide a powerful approach to identify biomarkers for personalized medicine. Particularly, biomarkers for early detection, prognosis and therapeutic intervention of bone cancers, especially osteosarcomas, are missing. Initially, we compared two-dimensional gel electrophoresis (2-DE)-based protein expression pattern between cell lines of fetal osteoblasts, osteosarcoma and pulmonary metastasis derived from osteosarcoma. Two independent statistical analyses by means of PDQuest® and SameSpot® software revealed a common set of 34 differentially expressed protein spots (p < 0.05). 17 Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in one high-ranked network associated with Gene Expression, Cell Death and Cell-To-Cell Signaling and Interaction. Ran/TC4-binding protein (RANBP1) and Cathepsin D (CTSD) were further validated by Western Blot in cell lines while the latter one showed higher expression differences also in cytospins and in clinical samples using tissue microarrays comprising osteosarcomas, metastases, other bone malignancies, and control tissues. The results show that protein expression patterns distinguish fetal osteoblasts from osteosarcomas, pulmonary metastases, and other bone diseases with relevant sensitivities between 55.56% and 100% at ≥87.50% specificity. Particularly, CTSD was validated in clinical material and could thus serve as a new biomarker for bone malignancies and potentially guide individualized treatment regimes.

Total hip replacements for older patients are usually cemented to ensure high postoperative primary stability. Curing temperatures vary with implant material and cement thickness (30°C to 70°C), whereas limits for the initiation of thermal bone damage are reported at 45°C to 55°C. Thus, optimizing surgical treatment and the implant material are possible approaches to lower the temperature. The aim of this study was to investigate the influence of water cooling on the temperature magnitude at the acetabulum cement interface during curing of a modular cobalt-chromium cup and a monoblock polyethylene acetabular cup. The curing temperature was measured for SAWBONE and human acetabuli at the cement–bone interface using thermocouples. Peak temperature for the uncooled condition reached 70°C for both cup materials but was reduced to below 50°C in the cooled condition for the cobalt-chromium cup ( P = .027). Cooling is an effective method to reduce curing temperature with metal implants, thereby avoiding the risk of thermal bone damage.

Non-union continues to be one of the orthopedist’s greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether “aseptic” tibial non-union can be the result of an unrecognized infection.

Osteosynthesis of intraarticular tibial pilon fractures is preferably achieved using locking plates via a minimally invasive technique. If combined with severe soft tissue damage there is a high risk of wound-healing deficits after plate osteosynthesis. Thus our aim was to find an alternative method of treatment for those cases with combined soft tissue injuries.We report on five cases with comminuted fractures of the joint surface combined with critical soft tissue condition that were treated with lag screws and external fixation (AO) applied across the ankle joint. All five patients were followed up, undergoing clinical and radiological examination.Using this approach we achieved fracture healing of comminuted fractures without further complications. Clinical follow-up after an average of 55.6 (36-75) months revealed a mean AOFAS score of 81 (62-100).We therefore propose combined treatment using lag screws with external fixation as a practical treatment option for those fractures for which lag screws combined with a locking plate are not feasible or when there is a high risk of wound-healing deficits due to severe soft tissue damage.

Processus-coronoideus-Frakturen sind selten und therapeutisch anspruchsvoll. Mit der retrospektiven Nachuntersuchung der Patienten an einem überregionalen Traumazentrum sollten mittelfristige Behandlungsergebnisse gewonnen und prognostisch relevante Faktoren isoliert werden.

Background: A minimal invasive approach for elective hip surgery has been implemented in our institution in the past. It is widely hypothesized that implanting artificial hips in a minimal invasive fashion decreases surgical trauma and is helpful in the rehabilitation process in elective hip surgery. Thereby geriatric patients requiring emergency hip surgery also could theoretically benefit from a procedure that involves less tissue trauma.Methods: Sixty patients who sustained a fractured neck of femur were randomly assigned into two groups. In the minimal invasive arm, the so called "direct anterior approach" (DAA) was chosen, in the conventional arm the Watson-Jones-Approach was used for implantation of a bipolar hemi-arthroplasty. Primary outcome parameter was the mobility as measured by the four-item-Barthel index. Secondary outcome parameters included pain, haemoglobin-levels, complications, duration of surgery, administration of blood transfusion and external length of incision. Radiographs were evaluated.Results: A statistically significant difference (p = 0,009) regarding the mobility as measured with the four-item Barthel index was found at the 5th postoperative day, favouring the DAA. Evaluation of the intensity of pain with a visual analogue scale (VAS) showed a statistically significant difference (p = 0,035) at day 16. No difference was evident in the comparison of radiographic results.Conclusions: Comparing two different approaches to the hip joint for the implantation of a bipolar hemiarthroplasty after fractured neck of femur, it can be stated that mobilization status is improved for the DAA compared to the WJA when measured by the four-item Barthel index, there is less pain as measured using the VAS. There is no radiographic evidence that a minimal invasive technique leads to inferior implant position. Level of Evidence: Level II therapeutic study.

Cemented modular metal backed total hip prostheses have the theoretical advantage to allow different inlays to be used. Asymetric or snap inlays are some of the options. First attempts with this kind of implant failed due to PE quality. A novel implant has been specifically designed and constructed for the use of cement. In vitro testing has shown results equal to other cemented cups. Aim of this study is to investigate the first clinical results of this implant with special consideration to intraoperative complications, intraoperative change of inlays, postoperative complications and clinical results. Patients and Methods: Study setup was prospective, location a university hospital, approval for this study was granted by the local ethical committee. Inclusion criteria were patients with a biological age over 70 years that suffered a recent fractured neck of femur with the general indication for arthroplasty. Exclusion criteria were the inability for full informed consent, ASA IV and current infection. Thirty patients were included in this study. Mean age was 78.6 years (55.1 to 88.6), 23 patients were female (77%). The mean BMI was 25.3 (17.5–41). The implant under investigation was a cemented modular acetabular component (C-MIC, ESKA Implants, Germany). The inlays are manufactured of highly crosslinked polyethylene. The standard protocols regarding DVT prophylaxis and antibiosis for HHS and the Barthel index. Results: Implantation of the C-MIC component was possible in all cases. In 1 case (3.3%) the inlay was changed and replaced by an asymmetrical anti-luxation inlay intraoperatively as there was a luxation tendency. There were no other intraoperative complications. There was no case of infection or significant hematoma. In 1 case there was a DVT of the lower leg diagnosed by ultrasound on day 21. The mean Barthel index preop. was determined with 96.5 of 100, the mean Harris Hip Score with 89. At 3 months F/U the Barthel index was mean 96.1, at 6 months 96. The Harris Hip Score at 3 months was mean 72 points (17 pts below the preoperative status), at 6 months mean 79 points (10 pts below preoperative status). Discussion: The C-MIC acetabular component does not show increased complication rates when compared to published results of hemiarthroplasty. The Barthel index as an outcome measurement of mobility and activities of daily living showed a return to the preoperative level. The HHSshowed a satisfactory result at 12 weeks, it also showed that patients of a geriatric population have problems to regain their full hip function after a fractured neck-of-femur. We can conclude that the C-MIC acetabular component is safe to use. Due to limitations of this study we are not able to state if THA is superior to hemiarthroplasty in geriatric patients.

Introduction: Less invasive surgical technique in THA is expected to minimize soft tissue damage and expedite rehabilitation. Due to this, it is now in widespread use in elective THA. The large geriatric patient population suffering a fractured neck of femur thereby would also benefit of this technique. Aim of this study was to evaluate if this technique is feasible in the non-elective setting of geriatric patients and if there are benefits regarding clinical and social outcome. Patients and Methods: Study setup is a prospective randomized trial with a positive Ethical Committee vote. Included were patients under legal care of a third party. Inclusion criteria were the indication for bipolar hip arthroplasty including grade ASA 4; exclusion criteria included neoplastic disease and rheumatoid arthritis. Setting is a large university hospital. After biometrical evaluation, each arm was set as 30 patients. Primary end point was the modified Barthel index. 48 patients were female. Mean age for female patients was 85.5, for male 82.9 years. There was no detectable difference in the groups regarding age, sex and BMI. As a less invasive approach, the well described „Direct Anterior Approach-DAA”(modified Smith-Petersen approach) was chosen. In the other arm the Watson-Jones approach was used. The ABG II stem with a bipolar UHR head (Stryker) were used in both groups. To minimize the learning curve, 10 cadaver- and 15 clinical procedures were performed with the DAA approach before the study. The pre- and postoperative regimen was identical in both arms. The modified Barthel index and other clinical parameter were determined preoperatively and at 4 postoperative intervals up to 40 days. Results: There were no statistical differences between both groups for intra- and postoperative complications. The mean theatre time was 4.8 minutes longer for the DAA group, in the first 10 patients this difference was measured with 16 minutes. The Barthel Index was only statistically different at 40 days, at this time the DAA patients had reached their preoperative mobility level whilst the conventional approach patients (with a pre-operative level of 42.5) were measured with 25 points. The hemoglobin levels on day 5 and 16 were significantly different with a higher Hb for the DAA group. All other parameters showed no significant difference. Conclusion: The DAA approach has a clear learning curve. Once this has passed, the theatre time is only slightly longer. There is a detectable benefit regarding early rehabilitation and a slight but significantly reduced blood loss.