Development of a test system to analyze different hip fracture osteosyntheses under simulated walking

The mechanical complications of osteosyntheses after hip fractures are previously investigated by mostly static or dynamic uniaxial loading test systems. However, the physiologic loading of the hip joint during a normal gait is a multiplanar, dynamic movement. Therefore, we constructed a system to test osteosyntheses for hip fractures under physiologic multiplanar loading representative of normal gait. To evaluate the testing system, 12 femora pairs were tested under 25,000 cycles with two standard osteosyntheses (Proximal Femoral Nail Antirotation/Gamma3 Nail). For angular movement, the varus collapse to cut out (proportional to(CO)) (proportional to(CO) = 4.8 degrees +/- 2.1 degrees for blade and proportional to(CO) = 7.8 degrees +/- 3.8 degrees for screw) was the dominant failure mode, and only slight rotational angle shifts (proportional to(Rot)) (proportional to(Rot) = 1.7 degrees +/- 0.4 degrees for blade and proportional to(Rot) = 2.4 degrees +/- 0.3 degrees for screw) of the femoral head around the implant axis were observed. Angular displacements in varus direction and rotation were higher in specimens reinforced with screws. Hence, the cut out model and the migration directions showed a distinction between helical blade and hip screw. However, there were no significant differences between the different implants. The new setup is able to create clinical failures and allows to give evidence about the anchorage stability of different implant types under dynamic gait motion pattern

Is the rotation of the femural head a potential initiation for cutting out? A theoretical and experimental approach

We conclude the center-center position in the head of femur of any kind of lag screw or blade is to be achieved to minimize rotation of the femoral head and to prevent further mechanical complications

Funktionen zur Orientierung in einem virtuellen, kollaborativen Wörterbuch (ENFORUM) - theoretische Grundlagen und Implementierung

Hypermediale Formen der Wissensrepräsentation weisen interessante Merkmale auf, die für die Informationslokalisierung bei unsicherer Bedarfssituation oder einer nur interessegeleiteten Arbeit von hoher Bedeutung sind. Jedoch sind im Zusammenhang mit der assoziativen Präsentation von Inhalten und fehlenden Merkmalen konventioneller Medien, auch Nachteile durch Orientierungsverlust, kognitive Überlastung und der Unfähigkeit der Lokalisierung bekannter oder unbekannter Inhalte zu verzeichnen. Orientierungs- und Navigationsmittel sind eine Möglichkeit diese Probleme zu mindern. In dieser Arbeit werden nach der grundlegenden Erörterung kognitiver Aspekte und der Ableitung von Erkenntnissen aus der Orientierung und Navigation in der Realwelt, mögliche Ausprägungen von Orientierungsmitteln in einer Taxonomie gegenübergestellt und eingeordnet. Aspekte des Einsatzes einzelner Ausprägungen und der Möglichkeiten für die Visualisierung von grafikbasierten Orientierungsmitteln wurden besonders expliziert. Aus den gewonnenen Erkenntnissen wird in Hinblick auf die Ergänzung von Orientierungsfunktionen für das virtuelle, kollaborative Wörterbuch ENFORUM eine Auswahl möglicher Orientierungsmittel analysiert und bezüglich der an sie gestellten Anforderungen spezifiziert. Mögliche Vorgehensweisen und technische Grundlagen einer Implementierung werden erarbeitet. Schließlich wird die Implementierung einer Auswahl der spezifizierten Orientierungsformen für die Verwendung mit dem Wörterbuchsystem ENFORUM beschrieben

Elbow Dislocations: A Review Ranging from Soft Tissue Injuries to Complex Elbow Fracture Dislocations

This review on elbow dislocations describes ligament and bone injuries as well as the typical injury mechanisms and the main classifications of elbow dislocations. Current treatment concepts of simple, that is, stable, or complex unstable elbow dislocations are outlined by means of case reports. Special emphasis is put on injuries to the medial ulnar collateral ligament (MUCL) and on posttraumatic elbow stiffness

The influence of radio frequency ablation on intra-articular fluid temperature in the ankle joint - a cadaver study

Abstract Background Radio frequency ablation devices have found a widespread application in arthroscopic surgery. However, recent publications report about elevated temperatures, which may cause damage to the capsular tissue and especially to chondrocytes. The purpose of this study was the investigation of the maximum temperatures that occur in the ankle joint with the use of a commercially available radio frequency ablation device. Methods Six formalin-fixed cadaver ankle specimens were used for this study. The radio frequency device was applied for 120 s to remove tissue. Intra-articular temperatures were logged every second for 120 s at a distance of 3, 5 and 10 mm from the tip of the radio frequency device. The irrigation fluid flow was controlled by setting the inflow pressure to 10 mmHg, 25 mmHg, 50 mmHg and 100 mmHg, respectively. The controller unit voltage setting was set to 1, 5 and 9. Results Maximum temperatures exceeding 50 °C/122 °F were observed for all combinations of parameters, except for those with a pressure of 100 mmHg pressure. The main critical variable is the pressure setting, which is highly significant. The controller unit voltage setting showed no effect on the temperature measurements. The highest temperature was 102.7 °C/215.6 °F measured for an irrigation flow of 10 mmHg. The shortest time span to exceed 50 °C/122 °F was 3 s. Conclusion In order to avoid temperatures exceeding 50 °C/122 °F in the use of radio frequency devices in arthroscopic surgeries of the ankle joint, it is recommended to use a high irrigation flow by setting the pressure difference across the ankle joint as high as feasible. Even short intervals of a low irrigation flow may lead to critical temperatures above 50 °C/122 °F. Level of Evidence Level II, diagnostic study

LUCL reconstruction of the elbow: clinical midterm results based on the underlying pathogenesis

Purpose!#!Traumatic and atraumatic insufficiency of the lateral ulnar collateral ligament (LUCL) can cause posterolateral rotatory instability (PLRI) of the elbow. The influence of the underlying pathogenesis on functional outcomes remains unknown so far. The objective of this study was to determine the impact of the initial pathogenesis of PLRI on clinical outcomes after LUCL reconstruction using an ipsilateral triceps tendon autograft.!##!Methods!#!Thirty-six patients were reviewed in this retrospective study. Depending on the pathogenesis patients were assigned to either group EPI (atraumatic, secondary LUCL insufficiency due to chronic epicondylopathia) or group TRAUMA (traumatic LUCL lesion). Range-of-motion (ROM) and posterolateral joint stability were evaluated preoperatively and at follow-up survey. For clinical assessment, the Mayo elbow performance (MEPS) score was used. Patient-reported outcomes (PROs) consisting of visual analogue scale (VAS) for pain, disability of arm, shoulder and hand (DASH) score, patient-rated elbow evaluation (PREE) score and subjective elbow evaluation (SEV) as well as complications were analyzed.!##!Results!#!Thirty-one patients (group EPI, n = 17; group TRAUMA, n = 14), 13 men and 18 women with a mean age of 42.9 ± 11.0 were available for follow-up evaluation (57.7 ± 17.5 months). In 93.5%, posterolateral elbow stability was restored (n = 2 with re-instability, both group TRAUMA). No differences were seen between groups in relation to ROM. Even though group EPI (98.9 ± 3.7 points) showed better results than group TRAUMA (91.1 ± 12.6 points) (p = 0.034) according to MEPS, no differences were found for evaluated PROs (group A: VAS 1 ± 1.8, PREE 9.3 ± 15.7, DASH 7.7 ± 11.9, SEV 92.9 ± 8.3 vs. group B: VAS 1.9 ± 3.2, PREE 22.4 ± 26.1, DASH 16.0 ± 19.4, SEV 87.9 ± 15.4. 12.9% of patients required revision surgery.!##!Conclusion!#!LUCL reconstruction using a triceps tendon autograft for the treatment of PLRI provides good to excellent clinical outcomes regardless of the underlying pathogenesis (traumatic vs. atraumatic). However, in the present case series, posterolateral re-instability tends to be higher for traumatic PLRI and patient-reported outcomes showed inferior results.!##!Level of evidence!#!Therapeutic study, LEVEL III

Reattachment of the flexor and extensor tendons at the epicondyle in elbow instability: a biomechanical comparison of techniques

Abstract Background Elbow dislocation represents a common injury, especially in the younger population. If treated surgically, the reattached tendons require a high amount of primary stability to allow for an early rehabilitation to avoid postoperative stiffness. The purpose of this study was to assess the biomechanical properties of a single and a double row technique for reattachment of the common extensor and common flexor muscles origin. We hypothesized that the double row technique would provide greater stability in terms of pullout forces than the single row technique. Methods Twelve cadaveric specimens were randomized into two groups of fixation methods for the common extensor tendon or the common flexor tendon at the elbow (1): a single row technique using two knotted 3.0 mm suture anchors, and (2) a double row technique using an additional knotless 3.5 mm anchor. The repairs were cyclically loaded over 500 cycles at 1 Hz from 10 N to a maximum of 100 N (extensors) or 150 N (flexors), and then pulled to failure. Stiffness and maximum load at failure and mode of failure were recorded and calculated. Results No significant differences in stiffness were observed between the two techniques for both the extensor and flexor reattachment (P = 0.701 and P = 0.306, respectively). The mean maximum load at failure indicated that the double row construct was significantly stronger than the single row construct. This was found to be true for both the extensor and flexor reattachment (213.6; SD 78.7 N versus 384.1; SD 105.6 N, P = 0.010 and 203.7; SD 65.8 N versus 318.0; SD 64.6 N, P = 0.013, respectively). Conclusions The double row technique provides significant greater stability to the reattached common flexor or extensor origin to the medial or lateral epicondyle. Thus, it should be considered in the development of improved repair techniques for stabilizers of the elbow. Study design Controlled laboratory study