Matthias Knobe

Peer teaching: a randomised controlled trial using student‐teachers to teach musculoskeletal ultrasound

Medical Education 2010: 44: 148–155

Arthroscopy or ultrasound in undergraduate anatomy education: a randomized cross-over controlled trial

BackgroundThe exponential growth of image-based diagnostic and minimally invasive interventions requires a detailed three-dimensional anatomical knowledge and increases the demand towards the undergraduate anatomical curriculum. This randomized controlled trial investigates whether musculoskeletal ultrasound (MSUS) or arthroscopic methods can increase the anatomical knowledge uptake.MethodsSecond-year medical students were randomly allocated to three groups. In addition to the compulsory dissection course, the ultrasound group (MSUS) was taught by eight, didactically and professionally trained, experienced student-teachers and the arthroscopy group (ASK) was taught by eight experienced physicians. The control group (CON) acquired the anatomical knowledge only via the dissection course. Exposure (MSUS and ASK) took place in two separate lessons (75 minutes each, shoulder and knee joint) and introduced standard scan planes using a 10-MHz ultrasound system as well as arthroscopy tutorials at a simulator combined with video tutorials. The theoretical anatomic learning outcomes were tested using a multiple-choice questionnaire (MCQ), and after cross-over an objective structured clinical examination (OSCE). Differences in student’s perceptions were evaluated using Likert scale-based items.ResultsThe ASK-group (n = 70, age 23.4 (20–36) yrs.) performed moderately better in the anatomical MC exam in comparison to the MSUS-group (n = 84, age 24.2 (20–53) yrs.) and the CON-group (n = 88, 22.8 (20–33) yrs.; p = 0.019). After an additional arthroscopy teaching 1% of students failed the MC exam, in contrast to 10% in the MSUS- or CON-group, respectively. The benefit of the ASK module was limited to the shoulder area (p < 0.001). The final examination (OSCE) showed no significant differences between any of the groups with good overall performances. In the evaluation, the students certified the arthroscopic tutorial a greater advantage concerning anatomical skills with higher spatial imagination in comparison to the ultrasound tutorial (p = 0.002; p < 0.001).ConclusionsThe additional implementation of arthroscopy tutorials to the dissection course during the undergraduate anatomy training is profitable and attractive to students with respect to complex joint anatomy. Simultaneous teaching of basic-skills in musculoskeletal ultrasound should be performed by medical experts, but seems to be inferior to the arthroscopic 2D-3D-transformation, and is regarded by students as more difficult to learn. Although arthroscopy and ultrasound teaching do not have a major effect on learning joint anatomy, they have the potency to raise the interest in surgery.

Unstable Intertrochanteric Femur Fractures: Is There a Consensus on Definition and Treatment in Germany?

BackgroundExtramedullary and intramedullary implants have improved in recent years, although consensus is lacking concerning the definition and classification of unstable intertrochanteric fractures, with uncertainties regarding treatment.Questions/purposesWe conducted a national survey of practicing chairpersons of German institutions to determine current perspectives and perceptions of practice in the diagnosis, management, and surgical treatment of unstable intertrochanteric fractures.MethodsBetween January and February 2010, we emailed 575 German chairpersons of trauma and/or orthopaedic departments, asking them to complete a 26-question web-based survey regarding three broad domains: fracture classification and instability criteria, implants and surgical treatment algorithms, and timing of operations. Response rate was 42%.ResultsThere was a clear preference for use of the AO/OTA fracture classification with geographic variations. Absence of medial support was considered the main criterion for fracture instability (84%), whereas a broken lateral wall and detached greater trochanter were considered by 4% and 5% of the respondents, respectively, to determine instability. Two percent routinely fixed unstable intertrochanteric fractures with extramedullary devices. Ninety-eight percent of German hospitals reportedly perform surgery within 24 hours after admission. Time to surgery was dependent on hospital level, with more direct surgeries in Level I hospitals.ConclusionsDespite varying opinions in the literature in recent years, we found some instability criteria (lateral wall breach, a detached greater trochanter) played a minor role in defining an unstable intertrochanteric fracture pattern. Despite recent meta-analyses suggesting clinical equivalence of intra- and extramedullary implants, few respondents routinely treat unstable intertrochanteric fractures with extramedullary plates. Additional studies are required to specify the influence of fracture characteristics on complication rate and function and to establish a classification system with clear treatment recommendations for unstable intertrochanteric fractures.Level of EvidenceLevel V, expert opinion. See the Instructions for Authors for a complete description of levels of evidence.

Biomechanical evaluation of locking plate fixation of proximal humeral fractures augmented with calcium phosphate cement.

Objectives: To evaluate the influence of calcium phosphate cement augmentation on failure of locking plate fixation of proximal humeral fracture fixation in a cadaveric fracture model. Methods: A 5-mm wedge osteotomy was created in each of 11 paired fresh-frozen human cadaveric humeri (age > 65 years). Specimens were randomly assigned to receive either locked plate fixation (group 1) or locked plate fixation with cement augmentation (group 2). Constructs were tested for axial stiffness, load to failure, and failure mode using a material testing machine. Results: Cement-augmented specimens resisted higher loads (1936 ± 609 N) in comparison to nonaugmented specimens (1373 ± 590 N) (P = 0.01). In group 1, varus displacement and glenohumeral screw perforation occurred in all cases. Varus displacement occurred in 2 cases in group 2, whereas glenohumeral screw perforation did not occur in any of the cases. Cement augmentation led to a significant increase in axial stiffness (P = 0.04). Conclusions: Calcium phosphate cement–augmented locking plates enhanced fixation stability in proximal humeral fractures and reduced glenohumeral screw perforation in this 2-part cadaveric model. The ultimate advantage of this method remains to be determined in vivo.

Rotationally Stable Screw-Anchor With Locked Trochanteric Stabilizing Plate Versus Proximal Femoral Nail Antirotation in the Treatment of AO/OTA 31A2.2 Fracture: A Biomechanical Evaluation

Objectives: Third-generation cephalomedullary nails currently represent the gold standard in the treatment of unstable trochanteric femur fractures. Recently, an extramedullary rotationally stable screw-anchor system (RoSA) has been developed. It was designed to combine the benefits of screw and blade and to improve stability using a locked trochanteric stabilizing plate (TSP). The purpose of this study was to compare the biomechanical behavior of RoSA/TSP and the proximal femoral nail antirotation (PFNA). Methods: Standardized AO/OTA 31A2.2 fractures were induced by an oscillating saw in 10 paired human specimens (n = 20; mean age = 85 years; range: 71–96 years). The fractures were stabilized by either the RoSA/TSP (Koenigsee Implants, Allendorf, Germany) or the PFNA (DePuy Synthes, Zuchwil, Switzerland). Femurs were positioned in 25 degrees of adduction and 10 degrees of posterior flexion and were cyclically loaded with axial sinusoidal pattern at 0.5 Hz, starting at 300 N, with stepwise increase by 300 N every 500 cycles until bone–implant failure occurred. After every load step, the samples were measured visually and radiographically. Femoral head migration was assessed. Results: The stiffness at the load up to the clinically relevant load step of 1800 N (639 ± 378 N/mm (RoSA/TSP) vs. 673 ± 227 N/mm (PFNA); P = 0.542) was comparable, as was the failure load (3000 ± 787 N vs. 3780 ± 874 N; P = 0.059). Up to 1800 N, no femoral head rotation, head migration, or femoral neck shortening were observed either for RoSA/TSP or PFNA. Whereas failure of the PFNA subsumed fractures of the greater trochanter and the lateral wall, a posterior femoral neck fracture with a significantly increased femoral neck shortening (1.7 mm vs. 0 mm; P = 0.012) was the cause of failure with RoSA/TSP. This specific kind of failure was induced by a femoral neck weakening caused by the posterior TSP stabilizing screw. Conclusions: There was no significant difference in biomechanical properties between the RoSA/TSP and the PFNA for the fracture pattern tested. However, failure modes differed between the 2 implants with greater femoral neck shortening observed in the RoSA/TSP group.

Hüftgelenknahe Frakturen im hohen Lebensalter

ZusammenfassungHintergrundOsteoporoseassoziierte Frakturen des Schenkelhalses und der trochantären Region stellen ein existenzielles Problem für den einzelnen Patienten, aber auch ein relevantes Problem für die Gesellschaft dar. Trotz zahlreicher Innovationen auf dem Implantatesektor persistiert bei diesen überwiegend multimorbiden Patienten neben einer hohen Mortalität eine hohe systemische wie auch mechanische Komplikationsrate.FragestellungDarstellung der Versorgungsoptionen bei der medialen Schenkelhalsfraktur sowie der pertrochantären Femurfraktur im Alter. Hierbei werden insbesondere gelenkersetzende und osteosynthetische Verfahren gegenübergestellt.Material und MethodeBasierend auf einer selektiven Literaturrecherche mit dem Schwerpunkt auf Arbeiten zu hüftgelenknahen Frakturen werden die Daten aus randomisierten kontrollierten Studien (RCTs) dargestellt und aktualisierte Metaanalysen und Reviews diskutiert.ErgebnisseWährend dislozierte mediale Schenkelhalsfrakturen eher einen Gelenkersatz erfordern, werden pertrochantäre Frakturen überwiegend osteosynthetisch versorgt. Ein prothetischer Ersatz sollte im Alter zementiert erfolgen und bietet bei aktiven Patienten als Totalersatz des Gelenks funktionelle Vorteile. Bei sehr alten Patienten mit diversen Vorerkrankungen oder Demenz ist die Hemiprothese Therapie der Wahl. Pertrochantäre Femurfrakturen können als A1- oder A2-Fraktur sowohl extra- wie auch intramedullär behandelt werden. Grundvoraussetzung für die komplikationslose Heilung ist eine adäquate Reposition mit stabiler und korrekter interner Fixation. Hier ist der Operateur selbst für einen Großteil der Komplikationen verantwortlich.SchlussfolgerungenInsgesamt existieren viele Parameter – aus Patientensicht, aus technischer Sicht und aus operateurspezifischer Sicht – die das Ergebnis nach Behandlung der hüftgelenknahen Fraktur im hohen Lebensalter beeinflussen. Die Lösung aller Probleme steht allerdings weiterhin aus, auch deshalb, weil der Faktor „Chirurg“ einen Großteil der Komplikationen bedingt. Auch wenn die Frakturentität Hinweise für das geeignete Verfahren liefert, müssen patientenspezifische Faktoren einbezogen werden. Die Entwicklung alterstraumatologischer Zentren in Deutschland kann helfen, die Komplikationsrate zu senken und die Lebensqualität der betagten Patienten zu erhöhen.AbstractBackgroundOsteoporotic fractures of the femoral neck and trochanteric region pose an ever-expanding existential problem both for the individual and for society. Despite numerous innovations and advances regarding implant design, mortality and the systemic and mechanical complication rates remain high.ObjectivesDepiction of treatment options for femoral neck fractures and trochanteric femur fractures in the elderly comparing joint replacement and osteosynthesis.MethodsA search of the Medline, Embase and Cochrane databases was carried out focusing on hip fracture treatment. Randomized or quasi-randomized controlled trials, meta-analyses and reviews comparing joint replacement or fixation implants in the elderly were included.ResultsDisplaced fractures of the femoral neck often require total joint arthroplasty whereas trochanteric fractures are amenable to internal fixation. Cemented total hip replacement as opposed to cementless techniques is recommended in the elderly and yields good functional results in active patients. Hemiarthroplasty is the treatment of choice in infirm patients with multiple comorbidities and cognitive impairment. Trochanteric fractures (AO/OTA types A1 and A2) can be successfully treated with intramedullary or extramedullary fixation. Adequate reduction and stable fixation are prerequisites for uneventful healing. A meticulous operative technique can prevent iatrogenic complications.ConclusionIn summary, there are many parameters affecting the outcome in the treatment of fragility and hip fractures. Technical features as well as surgeon characteristics play an important role and the ultimate solution has yet to be developed. Even though fracture morphology may indicate a specific treatment option, patient characteristics play an important role in decision-making. The development of centers of fragility fracture care in Germany could help to lower the complication rate and increase quality of life in hip fracture patients in the future.BACKGROUND Osteoporotic fractures of the femoral neck and trochanteric region pose an ever-expanding existential problem both for the individual and for society. Despite numerous innovations and advances regarding implant design, mortality and the systemic and mechanical complication rates remain high. OBJECTIVES Depiction of treatment options for femoral neck fractures and trochanteric femur fractures in the elderly comparing joint replacement and osteosynthesis. METHODS A search of the Medline, Embase and Cochrane databases was carried out focusing on hip fracture treatment. Randomized or quasi-randomized controlled trials, meta-analyses and reviews comparing joint replacement or fixation implants in the elderly were included. RESULTS Displaced fractures of the femoral neck often require total joint arthroplasty whereas trochanteric fractures are amenable to internal fixation. Cemented total hip replacement as opposed to cementless techniques is recommended in the elderly and yields good functional results in active patients. Hemiarthroplasty is the treatment of choice in infirm patients with multiple comorbidities and cognitive impairment. Trochanteric fractures (AO/OTA types A1 and A2) can be successfully treated with intramedullary or extramedullary fixation. Adequate reduction and stable fixation are prerequisites for uneventful healing. A meticulous operative technique can prevent iatrogenic complications. CONCLUSION In summary, there are many parameters affecting the outcome in the treatment of fragility and hip fractures. Technical features as well as surgeon characteristics play an important role and the ultimate solution has yet to be developed. Even though fracture morphology may indicate a specific treatment option, patient characteristics play an important role in decision-making. The development of centers of fragility fracture care in Germany could help to lower the complication rate and increase quality of life in hip fracture patients in the future.

Nitrate Patch Prevents Steroid-Related Bone Necrosis

Avascular necrosis of the femoral head is a common complication with disabling effect for young patients after high‐dose corticosteroid treatment. We could show that steroids have a vasoconstrictive effect on lateral epiphyseal arteries of the femoral head which could lead to ischemia and subsequent necrosis. In this study we investigated the preventive effect of a nitrate patch on steroid‐related bone necrosis in a rabbit model. New Zealand White rabbits (male; 3–4.5 kg bodyweight) were injected with 20 mg/kg bodyweight methylprednisolone (GC group; n = 6). Control animals (n = 6) were treated with phosphate‐buffered saline. A third group (GC + N; n = 6) additionally received a nitrate patch (0.675 mg/day). Four weeks after i.m. methylprednisolone injection the animals were sacrificed. For histology and immunohistochemistry, tissue samples were fixed in 3% paraformaldehyde, embedded in paraffin, sectioned, dewaxed, and stained with Ladewig. For quantification of empty lacunae, a histologic sign of FHN, histomorphometry was performed. Histomorphometry revealed a significant increase of empty lacunae in glucocorticoid‐treated animals compared to controls and GC + N‐treated animals. No significant difference in empty lacunae count was detected between the GC + N group and controls. HE staining revealed the different osteocyte amount in the GC versus GC and nitrate patch‐treated groups. This study demonstrates an increased number of empty osteocyte lacunae representing a pathologic feature of osteonecrosis, in the GC group. Less empty lacunae were counted in the GC animals after additional treatment with a nitrate patch. This finding suggests that nitrate co‐treatment has the potential to prevent steroid‐associated FHN.

Rotationally stable screw-anchor versus sliding hip screw plate systems in stable trochanteric femur fractures: a biomechanical evaluation.

Objectives: The rotationally stable screw-anchor plate system (RoSA) is unique in using a novel screw-blade combination. This investigation tested the hypothesis whether RoSA is advantageous over the sliding hip screw plate system (SHS) with regard to stiffness, failure load, displacement, and migration in stable trochanteric femur fractures (OTA 31A1.1). Methods: Thirteen femur pairs (mean age = 79 years; range, 64–92 years) received implants of either the RoSA or SHS (Koenigsee Implants, Allendorf, Germany). Beginning with 300 N and under consecutive 300 N load-increase steps (2000 cycles, 0.5 Hz) the femurs were cycled until failure. Specimens were evaluated for fragment displacement in both frontal and rotational planes and for migration. A survival analysis was carried out. Results: With regard to stiffness (526 ± 195 N/mm vs 358 ± 143 N/mm; P = 0.006) and the failure load (2838 ± 781 N vs 2262 ± 863 N; P = 0.012), the RoSA proved superior to the SHS. Furthermore, RoSA demonstrated higher rotational stability in comparison to the SHS (1800 N: 0 ± 0 degrees vs 1.1 ± 1.3 degrees; P = 0.015; failure point: 0 ± 0 degrees vs 2.3 ± 2.6 degrees; P = 0.008), measuring rotation about femoral neck axis over time. Whereas cutout occurred only in the RoSA system (n = 3; P = 0.110), the SHS underwent plastic deformation in 7 cases (n = 7; P = 0.003). In one case (7%), the insertion of the RoSA blade resulted in iatrogenic cut-through caused by a jamming of the screw and the blade. Conclusions: The fixation of stable trochanteric femur fractures with RoSA in cadavers led to greater primary stability under cyclic load, with significant advantages with regard to stiffness, failure load, and rotational stability, compared with the SHS. A detrimental effect was its migration tendency, which began at 1800 N and occurred in the cranial direction. A meticulous insertion technique was a prerequisite to avoid iatrogenic perforation of the femoral head. Our results will have to be substantiated by further biomechanical and clinical trials using an optimized RoSA system.

Effects of near cortical slotted holes in locking plate constructs.

The development of locked plating has led to substantial improvements in fracture fixation. This is particularly evident in periarticular fractures, in which conventional nonlocking plates are unable to support the articular surface from a single side. Initially, locked plating appeared to be the ideal solution for these situations and reduced the necessity for double plating and secondary bone grafting. However, with increasing use of locked plating, it became evident that the plate-bone interaction is rigid and may lead to impaired bone healing. The near cortical locking holes increased the construct stiffness and appeared to interfere with local healing. Slotted near cortical locking holes might improve this drawback. This review summarizes the current knowledge of the healing process associated with different types of near cortical locking options.

Locked minimally invasive plating versus fourth generation nailing in the treatment of AO/OTA 31A2.2 fractures: A biomechanical comparison of PCCP® and Intertan nail®☆

INTRODUCTION Locked minimally invasive plating and fourth generation nailing potentially could reduce the complication rate in the treatment of trochanteric femur fractures by its rotational stability and providing better lateral cortical support. The purpose of this study was (1) to compare the biomechanical properties of the Percutaneous compression plate (PCCP) and the Intertan nail (IT) with regards to implant failure and (2) to assess dynamic stability coefficients in an unstable AO/OTA 31A2.2 fracture model. METHODS In paired femurs, a standardised unstable trochanteric femur fracture was induced by an oscillating saw. The fractures were stabilised by either the PCCP (Orthofix, McKinney, TX, USA) or the IT (Smith & Nephew, Memphis, TN, USA). All femurs were loaded with 300N, followed by an increase in load until failure using 300N each time (2000 cycles each, 0.5Hz). After every load step the samples were assessed visually and radiographically. We measured migration and performed a survival analysis. RESULTS 16 fractures were induced in 8 paired human specimens (mean age: 84 years, 61-100 years). The mean stiffness (PCCP vs. IT: 249±124N/mm vs. 273±153N/mm; p=0.737) was comparable. The IT proved superior to the PCCP with regard to the number of cycles reached before failure occurred (PCCP vs. IT: 12,691±4733 vs. 15,313±4875 cycles; p=0.023). Except for a higher axial migration of the IT at failure point (PCCP vs. IT: 1.3mm vs. 4.3mm; p=0.028) there were no differences between the intra- and extramedullary implants, not even in terms of rotational stability along the femoral neck axis. A fracture of the femoral neck caused test abortion in both implants in most cases. CONCLUSION This study showed a superiority of the IT compared with the PCCP with regards to number of cycles achieved under sequential load increases for unstable trochanteric femur fractures. The stiffness was comparable. Both implants showed a high rotational stability and a support of the lateral wall. STUDY TYPE Biomechanical study.