[Posterolateral instability of the knee joint]. / Posterolaterale Instabilität des Kniegelenks.

The posterolateral corner of the knee is composed of a multilayered complex of ligamentous, musculotendinous, and capsular structures, which interact in a synergistic stabilizing manner with the central structures, particularly the posterior cruciate ligament. Injuries of the posterolateral corner are generally accompanied by rupture of the posterior cruciate ligament. Depending on the injured structures, injuries of the posterolateral corner result in posterolateral rotational instability alone (Fanelli A) or with lateral instability (Fanelli B/C). For rotational instability alone, isolated popliteus bypass is an effective procedure; with concomitant lateral instability in flexion, additional stabilization of the lateral collateral ligament is required. Most of the various available techniques are described as open reconstruction procedures. In recent years, arthroscopic techniques for posterolateral reconstruction have also been successfully developed.

Influence of leg axis alignment on MRI T2* mapping of the knee in young professional soccer players.

BACKGROUND: Investigation of the association between leg axis alignment and biochemical MRI in young professional soccer players in order to identify a potential influence of the leg axis on cartilage regions at risk. METHODS: Sixteen professional soccer players (21 ± 3 years) underwent static and dynamic leg axis analysis via radiation free DIERS formetric 4 D as well as 3-T MRI examination of both knees. Quantitative T2* mapping of the knee cartilage was performed and T2* values were evaluated as 144 regions of interest. Subgroup analysis was performed in players with severe varus alignment (> 6°). RESULTS: Analysis of the leg axis geometry revealed a mean static alignment of 6.6° ± 2.5 varus and a mean dynamic alignment of 5.1° ± 2.6 varus. Quantitative T2* mapping showed significantly increased T2* values in the superficial cartilage layer compared to the deeper region (p < 0.001) as well as a significant increase in relaxation times in the femoral cartilage from anterior to intermediate to posterior (p < 0.001). Combination of both methods revealed a significant correlation for the degree of varus alignment and the femoral, posterior, deep region of the medial knee compartment (r = 0.4; p = 0.03). If severe varus alignment was present this region showed a significant increase in relaxation time compared to players with a less pronounced leg axis deviation (p = 0.003). CONCLUSION: This study demonstrates that varus alignment in young soccer players is associated with elevated T2* relaxation times in the deep cartilage layer of the medial, posterior, femoral compartment and might therefore be a contributing factor in the early pathogenesis of manifest cartilage lesions. Therefore, these findings should be considered in the development of preventive training programs.

Current standard of care for distal femur fractures in Germany and Switzerland.

BACKGROUND: Distal femur fractures occur with an incidence of 4.5/100,000 and show a prevalence of 0.4%. Causes include low-impact trauma in older patients and high-impact trauma in younger patients without pre-existing medical conditions. The aim of this study was to perform a comprehensive evaluation of trauma mechanisms, trauma-promoting factors, comorbidities, medication history and type of surgical care to provide an overview of the causes of injury and the most appropriate therapeutic approach. METHODS: In this multicenter cohort study a retrospective analysis of 229 patients who sustained a distal femur fracture between January 2011 and December 2020 was performed. Individual fracture patterns, fracture predisposing factors, concomitant disease profiles, medication history, treatment strategy and associated complications were analyzed. RESULTS: 229 patients were included in the retrospective analysis. A total of 113-type 33 A, 50-type 33 B and 66-type 33 C fractures were diagnosed, of whom 92% received a lateral locking plate osteosynthesis. There was a complication in 14.4% of all cases, of which 6.1% were attributable to infection. Significant risk factors for developing a complication were an increased BMI (29.9 ± 8.5 kg/m2; p = 0.04), fracture displacement of over half a shaft width (p < 0.001) and AOC fractures (p < 0,016), specifically C2 fractures (p < 0,008). CONCLUSION: In this multicenter retrospective cohort study, lateral locking plate osteosynthesis was the method of choice and was selected in over 90% of cases, regardless of the fracture classification and risk factors. A complication rate of 14.4% emphasizes the necessary analysis of patient- and care-specific risk factors and a resulting adjustment of the therapy strategy. An increased BMI (29.9 ± 8.5 kg/m2; p = 0.04), fracture displacement of over half a shaft width (p < 0.001) and AOC fractures (p < 0,016), specifically C2 fractures (p < 0,008) increase the risk of developing a complication and should prompt an early switch to a treatment strategy that provides more stability.

Treatment outcome of the Masquelet technique in 195 infected bone defects-A single-center, retrospective case series.

BACKGROUND: The Masquelet technique is a surgical procedure for the reconstruction of bone defects. During the first step, an osteosynthetically stabilized defect is filled with a cement spacer. The spacer induces a foreign body membrane, called a Masquelet membrane. In a follow-up procedure, the spacer is replaced by a bone graft, which ossifies in the subsequent phase. MATERIAL AND METHODS: A total of 171 patients with 195 septic bone defects on the extremities that had been treated with the Masquelet procedure at the BG Klinikum in Hamburg, Germany, from 2011 to 2021 were retrospectively analysed, comparing patients who reached full weight and load bearing on the affected extremity to those who failed to do so. Defect size and configuration, microbiological results and treatment methods as well as comorbidities and epidemiologic data were analysed for factors influencing the treatment outcome. RESULTS: In all, 113[66%] of the patients were male, and 58[34%] were female, with an age distribution of 52 +/-16 years. Out of 171 patients, 24 patients had two defects. The number of patients that reached full weight bearing was 152[89%], the follow-up period was 2 +/-1 years (median +/- SD). Full weight bearing capability was negatively by the defect size as defects >62 mm tended to be less likely to reach full weight bearing than smaller defects. A secondary stabilization with an internal stabilization was applied in 58[34%] of all patients and positively influenced the attainment of full weight and load bearing. DISCUSSION: With 171 patients and 195 septic bone defects treated at a single centre with the Masquelet Technique, this study represents a comparably large cohort. Demographics, defect characteristics and treatment outcomes did not differ from those of other cohorts described in the literature. Defects larger than 62 mm showed lower chances to reach full weight bearing and can be defined as "critical defect size" for the Masquelet technique based on our data.

ACL reconstruction provides superior stability than ACL repair in patients with Schenck III and IV knee joint dislocations: first results of a 12 month follow-up study.

PURPOSE: Acute knee dislocation is a rare but devastating multi-ligamentous knee injury with only limited evidence-based surgical technique recommendations. The aim of this study was a comparison of two different anterior cruciate ligament (ACL) restoration techniques as part of an early total surgical care concept: (1) repair of ACL with additional internal bracing (ACLIB) compared to; (2) ACL reconstruction with autograft (ACLR). METHODS: Retrospective, clinical-study of patients with an acute type III or IV knee dislocation (according to Schenck classification), in which the ACL was treated with ACLIB or ACLR within 12 days. The PCL was sutured and internally braced in all cases. Medial and lateral complex injuries were repaired and additionally laterally augmented by an Arciero reconstruction. After a minimum 12 months follow-up different patient-reported outcome measurements (IKDC, Lysholm, VAS, Tegner Score) and instrumental stability assessment by Rolimeter -test and stress radiographs (Telos™) were analyzed. Groups were compared by t test with p < 0.05 considered significant. RESULTS: In total, 20 patients (5 IIIM, 5 IIIL and 10 IV) were included in this study with an average follow-up of 13.7 ± 2.6 months. There were significant differences in instrumental stability testing (side-to-side difference (SSD) of anterior tibial translation: ACLIB 2.7 ± 1.5 mm vs. ACLR 1.3 ± 1.3; p = 0.0339) and stress radiography (SSD ACL: ACLIB 3.4 ± 2.2 mm vs. ACLR 0.4 ± 2.7; p = 0.0249) between groups. ACLIB group showed greater ROM in terms of flexion (SSD Flexion: ACLIB 7.8 ± 9.9° vs. ACLR 16 ± 7.0°; p = 0.0466; Total Flexion overall 125.5 ± 11.8°). No clinically relevant differences in patient-reported outcome scores (Lysholm Score: ACLIB 82 ± 16.4 vs. ACLR 85 ± 10.4; IKDC subjective score: ACLIB 70.4 ± 17 vs. ACLR 76.6 ± 8.3) were determined. CONCLUSION: ACLR provides superior translational stability than ACLIB in terms of instrumental testing and stress radiography. Both techniques were equivalent with respect to PROMS and led to good and excellent clinical results. LEVEL OF EVIDENCE: Retrospective cohort study, III.

[Osteosynthesis of extra-articular proximal tibial fractures]. / Osteosynthese bei extraartikulärer proximaler Tibiafraktur.

The treatment of extra-articular proximal tibial fractures is a therapeutic challenge due to the frequently significant soft tissue injury, the effect of the deforming forces and the need for an exact restoration of the bony alignment. Various methods of osteosynthesis are available for surgical stabilization. The locking plate osteosynthesis is the most frequently used procedure because of its good biomechanical stability, especially in osteoporotic bones, and the protection of the periosteal blood flow. Depending on the extent and stability of the defect zone, especially in the case of a medial comminuted zone and the bone quality, bilateral plate osteosynthesis can be necessary. If the proximal fragment is big enough, closed reduction and intramedullary nailing are possible. In the case of severely compromised soft tissue or very short epiphyseal fragments, the construction of an external fixator, e.g. hybrid external fixator, is recommended, which also allows definitive treatment under early full weight bearing. The most important complications are axial and torsional malalignments.

Nanoscopy and an extended lateral approach can improve the management of latero-central segments in tibial plateau fractures: a cadaveric study.

INTRODUCTION: The objective of this investigation was to compare different techniques to improve visualization and reduction in tibial plateau fractures involving the central lateral segments. METHODS: Matched pairs of pre-fractured cadaveric tibial plateau fractures that include the central lateral segments were treated by either an anterolateral approach (supine) or PL approach (prone). Reduction was stepwise extended by additional fracturoscopy (FS), nanoscopy (NS) and lastly by epicondyle osteotomy (ECO). Reduction was analyzed by 3D scan and visualization of the lateral plateau was quantified. RESULTS: Ten specimens (3 pairs 41B3.1, 2 pairs 41C3.3) were analyzed. Fracture steps involving the antero-latero-central (ALC) segment were insufficiently reduced after fluoroscopy using both approaches (AL 2.2 ± 1.2 mm vs PL 2.2 ± 1.0 mm, p 0.95). Additional NS and ECO achieved optimized fracture reduction in the ALC segment (NS AL 1.6 ± 1.3 mm vs PL 0.8 ± 0.9 mm, p 0.32). NS provided visualization of the entire lateral plateau (PL 102.9% ± 7.4, AL 108.8 ± 19.2%), while fracturoscopy only allowed visualization of the ALL segment and partially of PLL and ALC segments (PL 22.0 ± 23.4%, AL 29.7 ± 18.3%). CONCLUSION: Optimized reduction of tibial head fractures with involvement of latero-central segments requires additional video-assisted reduction or extended approaches. Nanoscopy helps visualizing of the entire lateral plateau, when compared to fracturoscopy and may become a valuable reduction aid.

[Removal of a bent femoral nail : Case report: treatment strategy of a complex femoral deformity with a bent femoral nail in situ since 36 years]. / Entfernung eines verbogenen Femurnagels : Kasuistik: Behandlungsstrategie einer komplexen Femurdeformität mit einem seit 36 Jahren einliegenden, verbogenen Femurnagel.

To remove a bent femoral nail is always a challenging task for a surgeon. In the last 20 years several case reports and descriptions of techniques are to be found in literature, the goal being to weaken the nail at the apex and then straightening it in situ in most cases. Those reports all have one parameter in common: the necessity to remove the nail relates to a refracture of the femur.We report the case of a patient who presented with the explicit wish to have a bent femoral nail removed and a femoral angulation corrected because of pain in the ipsilateral hip. A femoral fracture had been treated by a Küntscher nail in 1982. A refracture with severe bending of the nail had occurred a short time later, which was treated conservatively without a second surgical procedure.We can show that a planned removal of a bent and well-osseointegrated Küntscher nail can be achieved without complications and that thereby a multiplane angulation in the femur can be corrected, paving the way for a future arthroplasty in this specific case.

Acromioclavicular joint suture button repair leads to coracoclavicular tunnel widening.

PURPOSE: Biomechanical evaluation of three different suture button devices used in acromioclavicular joint repair and analysis of their effect on post-testing tunnel widening. METHODS: Eighteen human shoulder girdles were assigned into three groups with a similar mean bone mineral density. Three different single-tunnel acromioclavicular repair devices were tested: (1) AC TightRope® with FiberWire; (2) AC Dog Bone™ Button with FiberTape; (3) Low Profile AC Repair System. Biomechanical testing was performed simulating the complex movement of the distal clavicle as follows. A vertical load of 80 N was applied continuously. The rotation of the clavicle about its long axis was set at 10° anterior and 30° posterior for 2500 cycles at 0.25 Hz. The horizontal translation of the clavicle was set at 6 mm medial and 6 mm lateral for 10,000 cycles at 1 Hz. The coracoclavicular distance was measured before and after testing. After testing, each sample underwent micro-CT analysis. Following 3D reconstruction, the area of the bone tunnels was measured at five defined cross sections. RESULTS: In TightRope® and Dog Bone™ groups, all samples completed testing, whereas in the Low Profile group, three out of six samples showed system failure. The mean absolute difference of coracoclavicular distance after testing was significantly greater in the Low Profile group compared to TightRope® and Dog Bone™ groups (4.3 ± 1.3 mm vs 1.9 ± 0.7 mm vs 1.9 ± 0.8 mm; p = 0.001). Micro-CT analysis of the specimens demonstrated significant tunnel widening in the inferior clavicular and superior coracoid regions in all three groups (p < 0.05). CONCLUSION: Significant tunnel widening can be observed for all devices and is primarily found in the inferior parts of the clavicle and superior parts of the coracoid. The Low Profile AC Repair System showed inferior biomechanical properties compared to the AC TightRope® and AC Dog Bone™ devices. Therefore, clinicians should carefully select the type of acromioclavicular repair device used and need to consider tunnel widening as a complication.

Preoperative joint line convergence angle correction is a key factor in optimising accuracy in varus knee correction osteotomy.

PURPOSE: This study aimed to identify and prevent preoperative factors that can be influenced in preoperative planning to reduce postoperative malcorrections. METHODS: The method used in this study was a retrospective two-centre analysis of 78 pre and postoperative fully weight-bearing radiographs of patients who underwent valgus osteotomy correction due to symptomatic medial compartment osteoarthritis. A computer software (TraumaCad®) was used to aim for an intersection point of the mechanical tibiofemoral axis (mTFA) with the tibia plateau at 55-60% (medial = 0%, lateral = 100%). Postoperative divergence ± 5% of this point was defined as over- and undercorrection. Preoperative joint geometry factors were correlated with postoperative malcorrection. Planning was conducted using the established method described by Miniaci (Group A) and with additional correction of the joint line convergence angle (JLCA) using the formula JLCA-2/2 (Group B). Additionally, in a small clinical case series, planning was conducted with JLCA correction. Statistical analysis was performed using (multiple) linear regression analysis and analysis of variance (ANOVA) with p < 0.05 considered significant. RESULTS: In 78 analysed cases, postoperative malcorrection was detected in 37.2% (5.1% undercorrection, 32.1% overcorrection). Linear regression analysis revealed preoperative body mass index (BMI, p = 0.04), JLCA (p = 0.0001), and osteotomy level divergence (p = 0.0005) as factors correlated with overcorrection. In a multiple regression analysis, JLCA and osteotomy level divergence remained significant factors. Preoperative JLCA correction reduced the planned osteotomy gap (A 9.7 ± 2.8 mm vs B 8.3 ± 2.4 mm; p > 0.05) and postoperative medial proximal tibial angle (MPTA: A 94.3 ± 2.1° vs B 92.3 ± 1.5°; p < .05) in patients with preoperative JLCA ≥ 4°. The results were validated using a virtual postoperative correction of cases with overcorrection. A case series (n = 8) with a preoperative JLCA > 4 revealed a postoperative accuracy using the JLCA correction of 3.4 ± 1.9%. CONCLUSION: Preoperative JLCA ≥ 4° and tibial osteotomy level divergence were identified as risk factors for postoperative overcorrection. Preoperative JLCA correction using the formula JLCA-2/2 is proposed to better control ideal postoperative correction and reduce MPTA. The intraoperatively realised osteotomy level should be precisely in accordance with preoperative planning. LEVEL OF EVIDENCE: III, cross-sectional study.

Imaging of the medial collateral ligament of the knee: a systematic review.

INTRODUCTION: The primary aim of this investigation was to systematically review relevant literature of various imaging modalities (magnetic resonance imaging (MRI), stress radiography and ultrasonography) in the assessment of patients with a medial collateral ligament (MCL) injury. MATERIALS AND METHODS: A systematic literature review of articles indexed in PubMed and Cochrane library was performed. Original research reporting data associated with medial gapping, surgical, and clinical findings associated with MCL injuries were considered for inclusion. The methodological quality of each inclusion was also assessed using a verified tool. RESULTS: Twenty-three imaging studies (magnetic resonance imaging (MRI) n = 14; ultrasonography n = 6; radiography n = 3) were ultimately included into the review. A total of 808 injured, and 294 control, knees were assessed. Interobserver reliabilities were reported in radiographic and ultrasonographic investigations with almost perfect agreement. MRI studies demonstrated agreement ranging between substantial to almost perfect. Intraobserver reliability was only reported in radiographic studies pertinent to medial gapping and was found to be almost perfect. Correlation of MRI with clinical findings was moderate to strong (65-92%). Additionally, MRI imaging was more sensitive in the detection of MCL lesions when compared to clinical examination. However, when compared to surgical findings, MRI underestimated the grade of instability in up to 21% of cases. Furthermore, MRI showed relatively inferior performance in the identification of the exact MCL-lesion location when compared to surgical findings. Interestingly, preoperative clinical examination was slightly inferior to stress radiography in the detection of MCL lesions. However, clinical testing under general anaesthesia performed similar to stress radiography. The methodological quality analysis showed a low risk of bias regarding patient selection and index testing in each imaging modality. CONCLUSION: MRI can reliably diagnose an MCL lesion but demonstrates limitations in its ability to predict the specific lesion location or grade of MCL instability. Ultrasonography is a widely available, radiation free modality, but is rarely used in clinical practice for detecting MCL lesions and clinical or surgical correlates are scarce. Stress radiography findings correlate with surgical findings but clinical correlations are missing in the literature. LEVEL OF EVIDENCE: IV.

[Publication performance of university orthopedic trauma surgery in Germany]. / Zur Publikationsleistung der universitären Unfallchirurgie in Deutschland.

BACKGROUND: One of the performance criteria of a university hospital is its publication activities. The aim of this bibliometric study was a comparative benchmarking of the publication activities of German orthopedic trauma surgery university hospitals. MATERIAL AND METHODS: The publication performance of the leading groups, consisting of chief and senior physicians, section and division heads of 39 German orthopedic trauma surgery university hospitals, was recorded over a period of 10 years (1 January 2010-31 December 2019). All publications that were listed in PubMed and for which the appropriate persons were first or last author were considered. In addition, the impact factor (IF) was determined. RESULTS: A total of 4438 publications were recorded published by 381 surgeons. The share of publishing authors was 72.8%. The articles were published in 545 journals. The average IF of all publications was 1.81. The publication activities of hospitals showed a wide range, this applied to both the number of publications and the IF generated by the individual author. The publication activity ranged from an average of 16.4 publications per author in the top-ranked hospital to 1.5 publications in the last-placed hospital. The same result was seen with the total IFs. In the highest ranking hospital according to this criterion the individual surgeon achieved on average of 42.1 cumulative IFs compared with 1.7 IFs in the last placed hospital. CONCLUSION: The publication performance of German orthopedic trauma surgery university hospitals showed a high variance, as was also found in other disciplines. The causes must remain open, but a different research motivation cannot be ruled out.

The Use of Mobile Applications for the Diagnosis and Treatment of Tumors in Orthopaedic Oncology - a Systematic Review.

The use of smartphone apps is an essential part of everyday life. Mobile applications offer enormous opportunities for dealing with challenges in public health, and their number increases every day. This paper aims to review the existing literature on mobile applications in orthopaedic oncology and to summarize the current mobile applications for musculoskeletal tumors. A systematic literature review was conducted regarding articles on mobile applications in orthopaedic and trauma surgery. The focus was on identifying mobile applications that can be used in the treatment of patients with musculoskeletal tumors. Two reviewers independently assessed study eligibility, extracted data, and appraised methodological quality. In addition, the Apple App Store and Google Play Store were searched for suitable mobile applications. Ninety-one articles describing a mobile application in orthopaedic and trauma surgery were identified. Three articles focused on a mobile application for musculoskeletal tumors. Additionally, seven mobile applications were available in the App/Play Stores dealing with bone or soft tissue tumors in orthopaedic oncology without corresponding scientific articles. Increasing numbers of mobile applications are being developed in orthopaedic and trauma surgery. Currently, only three scientific articles on mobile applications in orthopaedic oncology are present, yet several more applications are available without scientific medical evaluation. Since mobile applications can facilitate the everyday life of orthopaedic and trauma surgeons, it is worthwhile to be aware of new developments in this field. A regular scientific evaluation of the subject is important in order to classify the significance of these applications.

[Combined PCL ligament bracing and ACL reconstruction in acute knee dislocation (Schenck IV) - The Hamburg Approach : Video article]. / Hamburger Konzept der operativen Versorgungsstrategie einer akuten Kniegelenkluxation (Schenck IV) : Videobeitrag.

OBJECTIVE: Stepwise reconstruction of knee stability and physiological kinematics in acute knee dislocation. INDICATIONS: The operative technique is demonstrated in a case of multiligamentous injury of the knee with involvement of both cruciate ligaments and additional medial and lateral peripheral injuries (type IV according to Schenck classification). CONTRAINDICATIONS: Critical soft tissue conditions, infections, old age, obesity, lack of compliance. SURGICAL TECHNIQUE: Time-limited arthroscopy in order to primarily identify and treat posterior horn/root injuries of the meniscus and concomitant intra-articular injuries. Anatomical placement of anterior cruciate ligament (ACL) drill wires for later ACL tunnel drilling is arthroscopically guided. Subsequent conversion to an anteromedial arthrotomy and ligament bracing of the posterior cruciate ligament. The ACL is reconstructed using the ipsilateral semitendinosus tendon. Medial and lateral peripheral injures are anatomically reconstructed followed by a posterolateral augmentation in a technique described by Arciero. FOLLOW-UP: Limited weight bearing for 6 weeks and stepwise increase of flexion using a standard knee brace and close clinical monitoring. EVIDENCE: Ligament bracing of both cruciate ligaments is an established treatment technique in acute knee dislocations and has been proven to achieve good to excellent clinical results. In an ongoing clinical study primary ACL reconstruction as a modified treatment approach indicated superior stability in a 12-month follow-up in patients with acute knee dislocations.

All-suture anchor pullout results in decreased bone damage and depends on cortical thickness.

PURPOSE: To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness. METHODS: Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified. RESULTS: The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm3 vs. 212 mm3; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle. CONCLUSION: In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.

Biomechanical aspects of the posteromedial split in bicondylar tibial plateau fractures-a finite-element investigation.

PURPOSE: To gain principal insight into fixation techniques of a posteromedial split fragment in bicondylar tibial plateau fractures. METHODS: A computer simulation was performed, applying the finite-element method (FEM) to compare four methods of fixation of the posteromedial split fragment: lateral plate (model 1), lateral plate and kickstand screw (model 2), lateral plate and two antero-posterior lag screws (model 3), and lateral and posteromedial plate (model 4). The displacement of the fragment and material stresses in implants and bone under 2500 N axial load were analyzed. RESULTS: Maximal displacement of the posteromedial split fragment of 2.8 mm was found with a sole lateral plate. An added kickstand screw decreased the displacement to 1.46 mm. Added lag screws improved stability by a factor 4, with a maximal displacement of 0.76 mm. The double-plate configuration revealed 0.27 mm, a decrease of the displacement by a factor 10 compared to model 1. An additional analysis of posteromedial fragment displacements with osteoporotic bone, simulated by dividing the elastic modulus of the bone by a factor 2, turned out to be of relevant impact. For model 1, the calculations did not converge. The influence of bone quality was found to be 70% in model 2, 60% in model 3, and 40% in model 4. CONCLUSIONS: The results indicate that the additional fixation of a posteromedial split fracture by plate osteosynthesis might be advantageous in bicondylar tibial plateau fractures treated with lateral plating. This might be even more important in patients with low bone quality.

[Patellar dislocation : Causes and treatment]. / Patellaluxation : Ursachen und Therapie.

The causes of patellofemoral instability (PFI) are complex. In accordance with the current literature a classification was developed which clearly weights all entities and derives diagnostic and therapeutic consequences. It considers patellar instability and patellar maltracking or the complete loss of patellar tracking and differentiates into 5 types. Type 1: patellar dislocation without maltracking or instability with a low risk of redislocation. Type 2: high risk of redislocation, no maltracking. Type 3: instability and maltracking; reasons for maltracking are a) soft tissue contracture, b) patella alta, c) pathological tibial tuberosity trochlear groove (TTTG) distance, c) valgus deformities and e) torsional deformities. Type 4: massively unstable floating patella, which is based on a high-grade trochlear dysplasia. Type 5: maltracking without instability.

[Minimally invasive posterior and anterior stabilization of the thoracolumbar spine after traumatic injuries]. / Minimal-invasive dorsale und ventrale Stabilisierung der thorakolumbalen Wirbelsäule bei traumatischen Verletzungen.

Injuries of the thoracolumbar junction are the most common fractures of the spine due to their anatomical position and load. Common classification systems differentiate between stable and unstable injuries and thus also between operative and conservative therapy. The majority of injuries can be treated conservatively; however, unstable injuries require surgical treatment for a variety of reasons. In the grey area between stable and unstable injuries, a clinical decision based on clinical experience is necessary in order to select the best treatment. A wide variety of parameters must be included and a change in strategy from conservative to operative may also be necessary. Posterior instrumentation is the most common procedure; purely anterior stabilization is rarely used. The length of the instrumentation/spondylodesis depends on bone quality, age of the patient, and fracture. The decision as to whether anterior operative treatment should be performed depends on fracture morphology, success of reduction, and the resulting stability. The open surgical procedure is increasingly being replaced by minimally invasive procedures in posterior and anterior techniques but can be an advantage in complex injuries (B and C injuries according to AO). Hybrid procedures are also possible. This also applies to the treatment of osteoporotic fractures, since a clear assignment between traumatic and osteoporotic cause is not always easy and possible. This article describes the principles, the possible indications, and limitations of minimally invasive posterior and anterior stabilization.

[External fixator for temporary stabilization of complex periarticular knee fractures]. / Gelenkübergreifender Fixateur externe zur temporären Stabilisierung komplexer Frakturen des Kniegelenks.

OBJECTIVE: Temporary stabilization of the knee joint in order to minimize soft tissue strain until definitive surgery is possible. INDICATIONS: Bicondylar distal femoral and tibial plateau fractures, additional vascular injury, open fractures (second or third degree), severe soft tissue damage, unicondylar fracture with contralateral ligament tear, (open) knee dislocation, polytrauma. CONTRAINDICATIONS: Unsafe pin placement, severe osteoporosis. SURGICAL TECHNIQUE: Two femoral and tibial pins are connected by two rods and are spanned over the knee with two additional longitudinal rods via a tube-to-tube clamp. Alternatively, this can be facilitated by a direct connection of two rods in case of anteriorly placed femoral pins. A reasonable distance should be kept to open wounds, the fracture, and later operative approaches. The knee is fixed in 5-15° of flexion. POSTOPERATIVE MANAGEMENT: Definitive treatment depending on patient well-being and amenable soft tissue.