Nonoperative and Operative Soft-Tissue, Cartilage, and Bony Regeneration and Orthopaedic Biologics of the Elbow and Upper Extremity: An Orthoregeneration Network Foundation Review.

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and, optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electromagnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the elbow and upper extremity, including the tendons (lateral epicondylitis, medial epicondylitis, biceps tendonitis, triceps tendonitis), articular cartilage (osteoarthritis, osteochondral lesions), and bone (fractures, nonunions, avascular necrosis, osteonecrosis). Promising and established treatment modalities include hyaluronic acid; botulinum toxin; corticosteroids; leukocyte-rich and leukocyte-poor platelet-rich plasma; autologous blood; bone marrow aspirate comprising mesenchymal stromal cells (alternatively termed medicinal signaling cells and frequently mesenchymal stem cells [MSCs]) and bone marrow aspirate concentrate; MSCs harvested from adipose and skin (dermis) sources; vascularized bone grafts; bone morphogenic protein scaffold made from osteoinductive and conductive ß-tricalcium phosphate and poly-ε-caprolactone with hydrogels, human MSCs, and matrix metalloproteinases; and collagen sponge. Autologous blood preparations such as autologous blood injections and platelet-rich plasma show positive outcomes for nonresponsive tendinopathy. In addition, cellular therapies such as tissue-derived tenocyte-like cells and MSCs show a promising ability to regulate degenerative processes by modulating tissue response to inflammation and preventing continuous degradation and support tissue restoration.

Females show worse functional outcome and quality of life compared to males 2 years after meniscus surgery: Data analysis from the German Arthroscopy Registry.

PURPOSE: The purpose of this study was to investigate the impact of sex on knee function, activity and quality of life following meniscus surgery using data from the German Arthroscopy Registry. METHODS: This is a retrospective cohort study with data collected between 2017 and 2022. Patient-reported outcome measures (PROMs), namely Knee Injury and Osteoarthritis Outcome Score (KOOS), EuroQol Visual Analogue Scale (EQ Scale), and Marx Activity Rating Scale (MARS), were collected preoperatively and at 6, 12 and 24 months postoperatively. Data were analysed to examine differences between male and female patients regarding PROMs, pre-existing conditions, meniscus lesion types and surgical treatments. RESULTS: A total of 1106 female (36.6%) and 1945 male patients (63.7%) were included. Males were significantly younger than females and had a higher body mass index. Overall, there were four times more medial meniscus lesions (MMLs) (77.5%) than lateral meniscus lesions (LMLs) (27.9%). Degenerative LMLs were more frequent in females, while traumatic LMLs were more common in males. Frequencies of traumatic and degenerative MMLs were similar among males and females. Males had higher absolute KOOS irrespective of treatment or meniscus lesion type. Meniscus repair resulted in similar improvements in ΔKOOS for both sexes, while meniscus resection exhibited higher absolute KOOS for males at each time point. Males generally had higher EQ Scale and MARS than females. CONCLUSION: Greater improvements in knee function, activity and quality of life were observed in males. While MMLs appear to be comparable among sexes, the nature of LML differed significantly. These results may help surgeons to refine patient selection for specific treatments to improve overall clinical outcomes. LEVEL OF EVIDENCE: Level III.

Longitudinal Radiographic Bone Density Measurement in Revision Hip Arthroplasty and Its Correlation with Clinical Outcome.

The subjective analysis of conventional radiography represents the principal method for bone diagnostics in endoprosthetics. Alternative objective quantitative methods are described but not commonly used. Therefore, semi-quantitative methods are tested using digital computation and artificial intelligence to standardize, simplify, and ultimately improve the assessment. This study aimed to evaluate the correlation between relative density progressions and clinical outcomes. Radiographs and clinical examinations before and 24 and 48 weeks after surgery were obtained from sixty-eight patients with a modular hip stem. For the calculation of the relative bone density, the modal gray values of the Gruen zones were measured using ImageJ and were normalized by gray values of the highest and lowest ROI. The clinical outcomes were measured according to the Harris hip score before evaluating them for correlations. Analyses were performed separately for subgroups and bone regions. The Harris hip score increased from 44.15 ± 15.00 pre-operatively to 66.20 ± 13.87 at the latest follow-up. The relative bone density adjustment of Gruen zone 7 showed a significant correlation to its clinical outcome. Other bone adaptations could be realistically reproduced and differences by regional zones and patients' histories visualized. Next to the simplicity and that no additional examination is required, the method provides good semi-quantitative results and visualizes adaptations, which make it suitable for use.

Femoral defects in revision hip arthroplasty: a therapy-oriented classification.

INTRODUCTION: The complex field of femoral defects in revision hip arthroplasty displays a lack of standardized, intuitive pre- and intraoperative assessment. To address this issue, the femoral defect classification (FDC) is introduced to offer a reliable, reproducible and an intuitive classification system with a clear therapeutic guideline. MATERIALS AND METHODS: The FDC is based on the integrity of the main femoral segments which determine function and structural support. It focuses on the femoral neck, the metaphysis consisting of the greater and lesser trochanter, and the femoral diaphysis. The four main categories determine the location of the defect while subcategories a, b and c are being used to classify the extent of damage in each location. In total, 218 preoperative radiographs were retrospectively graded according to FDC and compared to intraoperatively encountered bone defects. To account for inter-rater and intra-rater agreement, 5 different observers evaluated 80 randomized cases at different points in time. RESULTS: A Cohens kappa of 0.832 ± 0.028 could be evaluated, accounting for excellent agreement between preoperative radiographs and intraoperative findings. To account for inter-rater reliability, 80 patients have been evaluated by 5 different observers. Testing for inter-rater reliability, a Fleiss Kappa of 0.688 could be evaluated falling into the good agreement range. When testing for intra-rater reliability, Cohens Kappa of each of the 5 raters has been analyzed and the mean was evaluated at 0.856 accounting for excellent agreement. CONCLUSION: The FDC is a reliable and reproducible classification system. It combines intuitive use and structured design and allows for consistent preoperative planning and intraoperative guidance. A therapeutic algorithm has been created according to current literature and expert opinion. Due to the combination of the FDC with the recently introduced Acetabular Defect Classification (ADC) a structured approach to the entire field of hip revision arthroplasty is now available.

Long-term cost-effectiveness of matrix-associated chondrocyte implantation in the German health care system: a discrete event simulation.

INTRODUCTION: Cartilage defects in the knee can be caused by injury, various types of arthritis, or degeneration. As a long-term consequence of cartilage defects, osteoarthritis can develop over time, often leading to the need for a total knee replacement (TKR). The treatment alternatives of chondral defects include, among others, microfracture, and matrix-associated autologous chondrocyte implantation (M-ACI). The purpose of this study was to determine cost-effectiveness of M-ACI in Germany with available mid- and long-term outcome data, with special focus on the avoidance of TKR. MATERIALS AND METHODS: We developed a discrete-event simulation (DES) that follows up individuals with cartilage defects of the knee over their lifetimes. The DES was conducted with a status-quo scenario in which M-ACI is available and a comparison scenario with no M-ACI available. The model included 10,000 patients with articular cartilage defects. We assumed Weibull distributions for short- and long-term effects for implant failures. Model outcomes were costs, number of TKRs, and quality-adjusted life years (QALYs). All analyses were performed from the perspective of the German statutory health insurance. RESULTS: The majority of patients was under 45 years old, with defect sizes between 2 and 7 cm2 (mean: 4.5 cm2); average modeled lifetime was 48 years. In the scenario without M-ACI, 26.4% of patients required a TKR over their lifetime. In the M-ACI scenario, this was the case in only 5.5% of cases. Thus, in the modeled cohort of 10,000 patients, 2700 TKRs, including revisions, could be avoided. Patients treated with M-ACI experienced improved quality of life (22.53 vs. 21.21 QALYs) at higher treatment-related costs (18,589 vs. 14,134 € /patient) compared to those treated without M-ACI, yielding an incremental cost-effectiveness ratio (ICER) of 3376 € /QALY. CONCLUSION: M-ACI is projected to be a highly cost-effective treatment for chondral defects of the knee in the German healthcare setting.

Germany has a high demand in meniscal allograft transplantation but is subject to health economic and legal challenges: a survey of the German Knee Society.

PURPOSE: To determine the current status and demand of meniscal allograft transplantation (MAT) in Germany among members of the German Knee Society (= Deutsche Kniegesellschaft; DKG). METHODS: An online survey was conducted between May 2021 and June 2021 and sent to all members of the DKG. The survey questionnaire consisted of 19 questions to determine the demand and technical aspects of MAT among the participants and to identify areas of improvement in MAT in Germany. RESULTS: Overall, 152 participants, 136 (89.5%) from Germany, 8 (5.3%) from Switzerland, 6 (4.0%) from Austria, and 2 (1.3%) from other countries completed the online survey, with the majority working in non-academic institutions. According to the regulations of the DKG, 87 (57.2%) participants were board certified as specialized knee surgeons and 97 (63.8%) worked primarily in the field of orthopedic sports medicine. MAT was considered clinically necessary in Germany by 139 (91.5%) participants. Patient age (83.6%), post-meniscectomy syndrome in isolated lateral (79.6%) and medial (71.7%) meniscus deficiency, and functional and athletic demands (43.4%) were the most important determinants to consider MAT in patients. Participants reported that reimbursement (82.9%), jurisdiction over the use of donor grafts (77.6%), and the availability of meniscal allografts (76.3%) are the main challenges in performing MAT in Germany. The most frequently used meniscal allograft types by 54 (35.5%) participants who had already performed MAT were fresh-frozen grafts (56.6%), peracetic acid-ethanol sterilized grafts (35.9%), and cryopreserved grafts (7.6%). Participants reported to perform suture-only fixation more often than bone block fixation for both medial (73.6% vs. 22.6%) and lateral (69.8% vs. 24.5%) MAT. CONCLUSION: More than 90% of the responding members of the DKG indicated that MAT is a clinically important and valuable procedure in Germany. Reimbursement, jurisdiction over the use of donor grafts, and the availability of meniscal allografts should be improved. This survey is intended to support future efforts to facilitate MAT in daily clinical practice in Germany. LEVEL OF EVIDENCE: Level V.

[Posterior meniscus root tears]. / Posteriore Wurzelverletzungen der Menisken.

Meniscus root tears are radial tears in the region of the posterior insertion zones. Medial root injuries usually occur in individuals > 50 years of age without adequate trauma and are associated with obesity and varus deformities. The root lesion leads to a loss of ring tension, which results in extrusion of the meniscus and a strong increase in joint pressure that is biomechanically equivalent to a complete meniscectomy. When indicating arthroscopic transosseous refixation of the medial root lesion, factors such as accompanying cartilage damage, osteoarthritis, obesity and varus deformity must be taken into account. Injuries to the root of the lateral meniscus are mostly observed in younger patients in combination with a rupture of the anterior cruciate ligament. Arthroscopic transosseous refixation in combination with cruciate ligament surgery is therefore also recommended for type I and type II lesions. In summary, both the medial and the lateral root lesions of the menisci are injuries with high biomechanical relevance.

No Difference in Ligamentous Strain or Knee Kinematics Between Rectangular or Cylindrical Femoral Tunnels During Anatomic ACL Reconstruction With a Bone-Patellar Tendon-Bone Graft.

BACKGROUND: As our understanding of anterior cruciate ligament (ACL) anatomy has evolved, surgical techniques to better replicate the native anatomy have been developed. It has been proposed that the introduction of a rectangular socket ACL reconstruction to replace a ribbon-shaped ACL has the potential to improve knee kinematics after ACL reconstruction. PURPOSE: To compare a rectangular femoral tunnel (RFT) with a cylindrical femoral tunnel (CFT) in terms of replicating native ACL strain and knee kinematics in a time-zero biomechanical anatomic ACL reconstruction model using a bone-patellar tendon-bone (BTB) graft. STUDY DESIGN: Controlled laboratory study. METHODS: In total, 16 fresh-frozen, human cadaveric knees were tested in a 5 degrees of freedom, computed tomography-compatible joint motion simulator. Knees were tested with the ACL intact before randomization to RFT or CFT ACL reconstruction using a BTB graft. An anterior translation load and an internal rotation moment were each applied at 0°, 30°, 60°, and 90° of knee flexion. A simulated pivot shift was performed at 0° and 30° of knee flexion. Ligament strain and knee kinematics were assessed using computed tomography facilitated by insertion of zirconium dioxide beads placed within the substance of the native ACL and BTB grafts. RESULTS: For the ACL-intact state, there were no differences between groups in terms of ACL strain or knee kinematics. After ACL reconstruction, there were no differences in ACL graft strain when comparing the RFT and CFT groups. At 60° of knee flexion with anterior translation load, there was significantly reduced strain in the reconstructed state ([mean ±standard deviation] CFT native, 2.82 ± 3.54 vs CFT reconstructed, 0.95 ± 2.69; RFT native, 2.77 ± 1.71 vs RFT reconstructed, 1.40 ± 1.76) independent of the femoral tunnel type. In terms of knee kinematics, there were no differences when comparing the RFT and CFT groups. Both reconstructive techniques were mostly effective in restoring native knee kinematics and ligament strain patterns as compared with the native ACL. CONCLUSION: In the time-zero biomechanical environment, similar graft strains and knee kinematics were achieved using RFT and CFT BTB ACL reconstructions. Both techniques appeared to be equally effective in restoring kinematics associated with the native ACL state. CLINICAL RELEVANCE: These data suggest that in terms of knee kinematics and graft strain, there is no benefit in performing the more technically challenging RFT as compared with a CFT BTB ACL reconstruction.

The Medial structures of the knee have a significant contribution to posteromedial rotational laxity control in the PCL-deficient knee.

PURPOSE: Various reconstruction techniques have been employed to restore normal kinematics to PCL-deficient knees; however, studies show that failure rates are still high. Damage to secondary ligamentous stabilizers of the joint, which commonly occurs concurrently with PCL injuries, may contribute to these failures. The main objective of this study was to quantify the biomechanical contributions of the deep medial collateral ligament (dMCL) and posterior oblique ligament (POL) in stabilizing the PCL-deficient knee, using a joint motion simulator. METHODS: Eight cadaveric knees underwent biomechanical analysis of posteromedial stability and rotatory laxity using an AMTI VIVO joint motion simulator. Combined posterior force (100 N) and internal torque (5 Nm) loads, followed by pure internal/external torques (± 5 Nm), were applied at 0, 30, 60 and 90° of flexion. The specimens were tested in the intact state, followed by sequential sectioning of the PCL, dMCL, POL and sMCL. The order of sectioning of the dMCL and POL was randomized, providing n = 4 for each cutting sequence. Changes in posteromedial displacements and rotatory laxities were measured, as were the biomechanical contributions of the dMCL, POL and sMCL in resisting these loads in a PCL-deficient knee. RESULTS: Overall, it was observed that POL transection caused increased posteromedial displacements and internal rotations in extension, whereas dMCL transection had less of an effect in extension and more of an effect in flexion. Although statistically significant differences were identified during most loading scenarios, the increases in posteromedial displacements and rotatory laxity due to transection of the POL or dMCL were usually small. However, when internal torque was applied to the PCL-deficient knee, the combined torque contributions of the dMCL and POL towards resisting rotation was similar to that of the sMCL. CONCLUSION: The dMCL and POL are both important secondary stabilizers to posteromedial translation in the PCL-deficient knee, with alternating roles depending on flexion angle. Thus, in a PCL-deficient knee, concomitant injuries to either the POL or dMCL should be addressed with the aim of reducing the risk of PCL reconstruction failure.

Research productivity during orthopedic surgery residency correlates with pre-planned and protected research time: a survey of German-speaking countries.

PURPOSE: The purpose of this study was to identify modifiable factors associated with research activity among residents working in orthopedic surgery and traumatology. METHODS: Residents at 796 university-affiliated hospitals in Austria, Germany, and Switzerland were invited to participate. The online survey consisted of questions that ascertained 13 modifiable and 17 non-modifiable factors associated with the residents' current research activities. Responses of 129 residents were analyzed. Univariate linear regression was used to determine the association of individual factors with the current research activity (hours per week). The impact of significant non-modifiable factors (with unadjusted p values < 0.05) was controlled for using multivariate linear regression. RESULTS: The univariate analysis demonstrated six non-modifiable factors that were significantly associated with the current research activity: a University hospital setting (p < 0.001), an A-level hospital setting (p = 0.024), Swiss residents (p = 0.0012), the completion of a dedicated research year (p = 0.007), female gender (p = 0.016), and the department's size (p = 0.048). Multivariate regression demonstrated that the number of protected research days per year (p < 0.029) and the percentage of protected days, that were known 1 week before (p < 0.001) or the day before (p < 0.001), were significantly associated with a higher research activity. CONCLUSIONS: As hypothesized, more frequent and predictable protected research days were associated with higher research activity among residents in orthopedic surgery and traumatology. LEVEL OF EVIDENCE: III.

Influence of the posterior cruciate ligament on kinematics of the knee during experimentally simulated clinical tests and activities of daily living.

Clinical outcomes following posterior cruciate ligament (PCL) reconstruction are often suboptimal. A better understanding of the biomechanical contributions of the PCL to knee stability under physiologic, clinically-relevant loading conditions could improve reconstruction techniques and outcomes. We employed a servohydraulic joint motion simulator to investigate the kinematics of intact and PCL-deficient knees during simulated clinical tests and activities of daily living(ADL), including gait, stair ascent and descent. PCL transection caused the tibia to be displaced posterior, relative to the intact joint, throughout flexion. PCL transection also increased the amount of posterior tibial displacement measured during posterior laxity testing by up to 9.6 ± 1.7 mm at 75° (p = 0.001). During internal-external rotational laxity testing, PCL transection increased the allowable internal and external rotation of the tibia, by up to 2.9 ± 0.5°at90° (p = 0.001) and 1.0 ± 0.2° at45°(p = 0.001), respectively. PCL transection did not have a significant effect on abduction-adduction kinematics or laxity, regardless of flexion angle. PCL transection resulted in a relative posterior displacement of the tibia during the stance phase of gait when the knee was extended (2.2 ± 2.2 mm, p = 0.045), and when the knee was flexed during stair ascent (2.4 ± 2.2 mm, p = 0.035) and descent (1.6 ± 1.4 mm, p = 0.037). Our results support previous studies of the role of the PCL on neutral joint kinematics and laxity, and provide new data quantifying the effect of PCL transection on AP kinematics during simulated ADL.

Cartilage Regeneration with a Cell-free Collagen Type 1 Matrix (Part 2 - Experimental Aspects). / Knorpelregeneration mittels zellfreier Kollagen-Typ-I-Matrix ­ Vergangenheit, Gegenwart und Zukunft (Teil 2 ­ experimentelle Aspekte).

Cartilage regeneration with cell-free matrices has developed from matrix-associated autologous cartilage cell transplantation (MACT) over ten years ago. Adjustments to the legal framework and higher hurdles for cell therapy have led to the procedures being established as an independent alternative to MACT. These procedures, which can be classified as matrix-induced autologous cartilage regeneration (MACR), all rely on the chemotactic stimulus of a cross-linked matrix, which mostly consists of collagens. Given the example of a commercially available type I collagen hydrogel, the physicochemical properties of such a matrix are explained and the available experimental data highlighted in more detail. The interaction between different cell types and the chemotactic properties of the collagen has been investigated extensively and, from a clinical point of view, today offers various reference points for a smart modification of the described method to further improve clinical outcomes. Since the origin of the cells in the ultimately formed repair tissue is still unrevealed, further investigations to clarify the exact mechanism are crucially needed.

Cartilage Regeneration with Cell-free Type 1 Collagen Matrix - Past, Present and Future (Part 1 - Clinical Aspects). / Knorpelregeneration mittels zellfreier Kollagen-Typ-I-Matrix ­ Vergangenheit, Gegenwart und Zukunft (Teil 1 ­ klinische Aspekte).

Cartilage regeneration with cell-free matrices has developed from matrix-associated autologous cartilage cell transplantation (MACT) over ten years ago. Adjustments to the legal framework and higher hurdles for cell therapy have led to the procedures being established as an independent alternative to MACT. These procedures, which can be classified as matrix-induced autologous cartilage regeneration (MACR), all rely on the chemotactic stimulus of a cross-linked matrix, which mostly consists of collagens. Given the example of a commercially available type I collagen hydrogel, the state of clinical experience with MACR shall be summarized and an outlook on the development of the method shall be provided. It has been demonstrated in the clinical case series summarized here over the past few years that the use of the matrix is not only safe but also yields good clinical-functional and MR-tomographic results for both small (~ 10 mm) and large (> 10 mm) focal cartilage lesions. Depending on the size of the defect, MACR with a collagen type I matrix plays an important role as an alternative treatment method, in direct competition with both: microfracture and MACT.

Directions for Research on Climate and Conflict.

The potential links between climate and conflict are well studied, yet disagreement about the specific mechanisms and their significance for societies persists. Here, we build on assessment of the relationship between climate and organized armed conflict to define crosscutting priorities for future directions of research. They include (1) deepening insight into climate-conflict linkages and conditions under which they manifest, (2) ambitiously integrating research designs, (3) systematically exploring future risks and response options, responsive to ongoing decision-making, and (4) evaluating the effectiveness of interventions to manage climate-conflict links. The implications of this expanding scientific domain unfold in real time.

Suture Tape Reduces Quadriceps Tendon Repair Gap Formation Compared With High-Strength Suture: A Cadaveric Biomechanical Analysis.

PURPOSE: To compare the biomechanical differences between quadriceps tendon (QT) repair with high-strength suture (HSS) versus suture tape (ST) with varying number of suture passes. METHODS: In total, 28 fresh-frozen QTs were randomized into 2 groups: (1) HSS; or (2) ST; specimens were then further randomized into subgroups of either 4 or 6 suture passes. Specimens were secured within a materials testing system and a 150-N preload was applied for 10 seconds followed by a cyclic loading protocol between 50 N and 250 N for 1000 cycles. Video was used to follow tracking markers used to calculate the magnitude of tendon displacement. Two-way univariate analysis of variance was used to determine the effect of suture type and passes on the displacement after preloading and mixed repeated-measures analysis of variance was used to determine the effect of suture type and passes on displacement following cyclic loading. RESULTS: There were large increases in displacement following the preload across all conditions (7.82 ± 3.64 mm), with no statistically significant differences between groups. There was a significant difference in the mean (± standard deviation) displacement between the ST (5.24 ± 2.82 mm) and HSS (7.93 ± 2.91 mm) starting at 200 cycles, which became more pronounced with successive testing out to 1000 cycles (P = .021). There were no significant difference with respect to the number of suture or tape passes. CONCLUSIONS: Following preloading at 150 N, significant displacement occurred in both QT repair groups. ST demonstrated significantly less displacement than HSS under cyclic loading and had greater ultimate failure loads. CLINICAL RELEVANCE: When performing QT repair, emphasis should be placed on appropriate pretensioning of sutures to at least 150 N before knot-tying. In addition, where available, ST should be used over HSS to reduce further cyclic elongation and improve ultimate failure loads.

Climate as a risk factor for armed conflict.

Research findings on the relationship between climate and conflict are diverse and contested. Here we assess the current understanding of the relationship between climate and conflict, based on the structured judgments of experts from diverse disciplines. These experts agree that climate has affected organized armed conflict within countries. However, other drivers, such as low socioeconomic development and low capabilities of the state, are judged to be substantially more influential, and the mechanisms of climate-conflict linkages remain a key uncertainty. Intensifying climate change is estimated to increase future risks of conflict.

The Role of Osteotomy in Chronic Valgus Instability and Hyperextension Valgus Thrust (Medial Closing Wedge Distal Femoral Varus Osteotomy and Lateral Opening Wedge High Tibial Osteotomy).

Chronic valgus instability with concomitant valgus malalignment is a challenging diagnosis that cannot be successfully treated with ligament surgery alone. Hyperextension valgus thrust may be a symptom of this configuration, expressing the need for thorough diagnosis and treatment. The present article will help to understand pathoanatomy and mechanisms of chronic valgus instability in combination with malalignment and provide a description of treatment techniques, in particular medial closing wedge distal femoral varus osteotomy (MCWDFVO) and lateral opening wedge high tibial osteotomy (LOWHTO), and their indications to deal with both issues simultaneously.

Who profits from three-dimensional optics in endoscopic surgery? Analysis of manual tasks under two-dimensional/three-dimensional optic vision using a pelvic trainer model.

Background: In endoscopic operations, direct binocular view, tissue sensation and depth perception get lost. It is still unclear whether the novel three-dimensional (3D) high-definition (HD) cameras are able to compensate the limited senses and how this affects the skill set of users with different endoscopic experience. This study aimed first to evaluate if the 3D technology improves depth perception, precision and space orientation as compared to conventional two-dimensional (2D) HD technology. The second aim was to determine the 3D influence on participants with different endoscopic experience. Methods: A total of 24 participants of different experience levels performed three different tasks on a pelvic trainer using the same thoracoscopic unit in 2D and 3D modes. Results were statistically analysed using Student's t-test and Pearson's product-moment correlation. Results: Across all the participants, we found that 3D optic vision significantly reduced the needed time to perform a defined difficult task in comparison to 2D. This difference was less pronounced in participants with higher experience level. Participants with eyeglasses performed slower in both 2D and 3D in comparison to participants with normal vision. Only participants with normal vision could significantly improve their completion times with 3D optic vision. Conclusions: By testing the novel generation of 3D HD cameras, we could demonstrate that the 3D optic of these systems improves depth perception and space orientation for novices and experienced users and especially inexperienced users benefit from 3D optic.

Heterotopic Ossification - Complication or Chance? / Heterotope Ossifikation ­ Komplikation oder Chance?

So far, there has been no clear explanation of the pathophysiological relationships in the development of HO. There is little experimental data dealing with the post-traumatic inflammatory response in terms of a balance between the repair of damaged muscle cells and the opposite response in its development. There are numerous indications regarding possible predisposing factors, such as existence of surrounding tissue hypoxia or the function of pro-angiogenic (VEGF e.g.) and osteoinductive (BMP e.g.) factors. These different scientific approaches offer the opportunity to clinically intervene. In our opinion, early intervention seems to make the most sense in terms of effectiveness and recurrence of HO. An important pathomechanism seems to be chronic inflammation. Currently, non-steroidal anti-inflammatory drugs are the most commonly prescribed prophylaxis drugs. The effectiveness and efficacy of non-steroidal anti-inflammatory drugs is limited by the time-limited release and the side effect potential. Therefore, it is interesting to focus future research towards the cross-talks between immunosuppressive downregulation of the inflammatory response and its effect on the balance between muscle regeneration and the development of HO.

Medial patellofemoral ligament reconstruction fails to correct mild patella alta in cases of patellofemoral instability-a case-control study.

PURPOSE: Medial patellofemoral ligament reconstruction (MPFL-R) is the gold standard in patella soft tissue surgery for patellofemoral instability. Although claimed, recent reports indicate that MPFL-R may fail to distalize the patella in mild cases of patella alta. The present study is a retrospective case-control study to compare radiographic patella height between MPFL-R and historical Insall's proximal realignment (IPR) pre- and post-operatively with respect to distalization and assess redislocation rates at a mid-term follow-up. METHODS: Sixty-four patients were age/sex matched (1:1), yielding 32 patients for group 1 MPFL-R (cases) and 32 patients for group 2 IPR (controls). Insall-Salvati, Blackburne-Peel and Caton-Deschamps indices were analyzed for differences pre- and post-operatively. An additional inter-rater reliability analysis was performed by means of intra-class correlation (ICC). Redislocation rates were considered as treatment failures in this study. RESULTS: ICC was excellent for all three patella indices. MPFL-R failed to show significant differences if compared to IPR with respect to distalization in mild stages of patella alta. Moreover, redislocation rates significantly favored MPFL-R (3.1%) over IPR (12.5%; p < 0.0001). CONCLUSIONS: MPFL-R has become a popular option to restore native patellofemoral biomechanics after ligament rupture. However, the procedure's potential to correct concomitant patella alta should not be overestimated and indications considered carefully.