Publications by authors named "Lena Hirtler"

78 Publications

Arthroscopic accessibility of the first metatarsophalangeal joint for osteochondral defects of the metatarsal head by two-portal technique - comparing joint distraction and plantarflexion.

Foot Ankle Surg 2022 Jul 19. Epub 2022 Jul 19.

Department of Orthopedics and Traumatology, Medical University of Vienna, Vienna, Austria.

Background: Several techniques and approaches for first metatarsophalangeal (MTP1) joint arthroscopy have been reported, where joint accessibility plays a key role. This study aimed to evaluate differences in arthroscopic accessibility of the first metatarsal head (MTH1) comparing non-invasive distraction and maximum plantarflexion in a two-portal approach.

Methods: Forty fresh-frozen lower leg specimens were included and divided into a distraction group (D-group) and a plantarflexion group (PF-group). A two-portal technique (1.9 mm-30°-scope) was used for arthroscopy, maximum reach at the MTH1 was marked. Following arthroscopy, specimens were dissected and examined for iatrogenic injuries. The reached area at the chondral surface was pinned and accessibility calculated.

Results: Accessibility of the MTH1 was 58.03 % ± 13.64 (D-group) and 55.93 % ± 10.30 (PF-group, p = 0.51). The dorsomedial hallucal nerve was injured in one specimen (2.5 %).

Conclusion: Maximum plantarflexion showed no difference in arthroscopic MTP1 joint accessibility compared to non-invasive distraction in a two-portal approach. During dorsomedial portal placement, the dorsomedial hallucal nerve is at risk for iatrogenic injury.
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http://dx.doi.org/10.1016/j.fas.2022.07.008DOI Listing
July 2022

Biomechanical Determination of Fracture Loads and Patterns of the Odontoid Process.

Spine (Phila Pa 1976) 2022 Jul 14. Epub 2022 Jul 14.

AO Research Institute Davos, Clavadelerstrasse 8, 7270, Davos, Switzerland.

Study Design: Laboratory study.

Objective: This study aimed to investigate the biomechanical competence and fracture characteristics of the odontoid process.

Summary Of Background Data: Odontoid fractures of the second cervical vertebra (C2) is the most common fracture type in cervical- and spine in general in the elderly. However, very little is known about the underlying biomechanical fracture mechanisms.

Methods: A total of 42 human C2 specimens were Scanned using a QCT, divided in 6 groups, and subjected to combined quasi-static loading at -15°, 0°, and 15° in sagittal plane and -50° and 0° in transverse plane until fracture. Bone mineral density (BMD), height, state of the fusion of the ossification centers, stiffness, yield load, and ultimate load were assessed.

Results: While the lowest values for stiffness, yield, and ultimate load were observed at load inclination of 15° in the sagittal plane, no statistically significant differences could be observed between the six groups (P=0.235, P=0.646, and P=0.505, respectively). BMD was positively correlate with the yield (r²=0.350, P<0.001), and ultimate load (r²=0.955, P<0.001), but not with the stiffness (r²=0.082, P=0.07). The analysis of the mechanical quantitates for specimens with clearly distinguishable fusion of the ossification centers (26 specimens) reveled less differences between the mean values.

Conclusion: Load direction plays a subordinate role in traumatic fractures of the odontoid process. BMD was associated with significant correlation to the biomechanical outcomes. Thus, odontoid fractures appear to be the results of an interaction between the load magnitude and bone quality.
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http://dx.doi.org/10.1097/BRS.0000000000004369DOI Listing
July 2022

Biomechanical evaluation of the proximal chevron osteotomy in comparison to the Lapidus arthrodesis for the correction of hallux valgus deformities.

Int Orthop 2022 Jul 18. Epub 2022 Jul 18.

Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.

Purpose: The proximal chevron osteotomy and the modified Lapidus arthrodesis are both procedures utilized for deformity correction in patients with severe symptomatic hallux valgus. The aim of the current study was to compare their biomechanical stability when using locking plate fixation.

Methods: Twelve matched pairs of human anatomical lower leg specimens underwent on one side a proximal chevron osteotomy with a medial locking plate and on the other side a modified Lapidus arthrodesis with a plantar locking plate utilizing an interfragmentary compression screw. All specimens underwent bone mineral density (BMD) assessment and were tested in a servohydraulic load frame which applied a load on the centre of the metatarsal head over 1000 loading cycles with subsequently ultimate load testing. Displacement of the proximal and distal bone segment, ultimate load, and bending stiffness were analyzed.

Results: Mean displacement of both procedures showed no statistically significant difference throughout all the loading cycles (0.213 ≤ p ≤ 0.834). The mean ultimate load of the proximal chevron osteotomy was 227.9 N (± 232.4) and of the modified Lapidus arthrodesis 162.9 N (± 74.6) (p = 0.754). The proximal chevron osteotomy (38.2 N/mm (± 24.9)) had a significantly higher bending stiffness compared to the modified Lapidus arthrodesis (17.3 N/mm (± 9.9)) (p = 0.009). There was no correlation between BMD and displacement in all loading cycles, ultimate load, and bending stiffness of either procedure (p > 0.05).

Conclusion: Although the bending stiffness of the chevron osteotomy was higher, there was no statistically significant difference between the surgical techniques in mean displacement and ultimate load. The BMD did not influence the overall stability of either reconstruction. Locking plate fixation increases the clinical value of the modified Lapidus arthrodesis by outweighing most of the biomechanical disadvantages in comparison to the proximal chevron osteotomy.
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http://dx.doi.org/10.1007/s00264-022-05514-xDOI Listing
July 2022

Autologous replacement of the head of the radius-proximal fibula versus second metatarsal base: an anatomic feasibility study.

Arch Orthop Trauma Surg 2022 May 9. Epub 2022 May 9.

Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.

Introduction: This study investigated the anatomic feasibility of a new surgical therapy option for radial head arthrosis using an autologous vascularized bone graft of the second metatarsal and proximal fibula to recreate the proximal radiohumeral joint.

Materials And Methods: Upper and lower extremities of eleven body donors were evaluated using CT prior to anatomic dissection. Several distinct anatomic parameters were measured on the ipsi- and contralateral radial and fibular head and the second metatarsal base: bone diameter, articular surface diameter, head height, metaphyseal (neck) diameter, articular surface radius, total articular surface area, and angulation of the articular surfaces (facet). Each dissection phase was photographed in a standardized fashion and all measurements were repeated by direct caliper-measurements.

Results: When comparing the proximal radius and fibula to search for anatomic similarities, similar values were found in the maximum articular surface diameter and minimum and maximum measures of the neck diameter. Comparing the proximal radius and the second metatarsal, statistically similar values were found in the maximum neck diameter performing direct measurements and CT evaluation, the maximum head diameter in CT evaluation and the articular facet angulation.

Conclusions: Neither the proximal fibula nor the base of the second metatarsal are ideal bone grafts for replacement of the head of the radius. The base of the second metatarsal might be a bit more suitable as a potential donor since the angulation of the proximal articular facet is similar to that of the radius.

Level Of Evidence: Level IV, anatomic study.
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http://dx.doi.org/10.1007/s00402-022-04460-yDOI Listing
May 2022

Association of damage to the coracohumeral ligament with anterosuperior rotator cuff degeneration revealed by anatomical dissection.

Sci Rep 2022 03 10;12(1):4238. Epub 2022 Mar 10.

Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, 1090, Vienna, Austria.

The coracohumeral ligament (CHL) is an important structure of the biceps pulley which also merges with the rotator cuff. Which role it actually plays in the pathogenesis of rotator cuff degeneration (RCD) and rotator cuff tears (RCT) is still a point of discussion. The hypothesis of this study was, that macroscopic injury to the anterosuperior part of the rotator cuff also includes parts of or the whole CHL. Forty fresh-frozen shoulders were dissected and examined, the morphology of the rotator cuff and the coracohumeral ligament were evaluated and existing lesions documented. 27.5% of the shoulder joints showed an anterosuperior full-thickness RCT. 57.5% of all examined shoulder girdles showed at least a partial rupture of the CHL. A highly significant correlation (p < 0.001, rho = 0.529) between the presence of rotator cuff tears and ruptures of the CHL was found. Cartilage damage within the anterosuperior section of the humeral head was observed in 20% cases. In rotator cuff degeneration and atraumatic rotator cuff tears of the elderly population, the pathomechanism of full-thickness RCT is based on repetitive anterosuperior glenoid impingement. This is especially supported by the identification of a higher frequency of CHL lesions compared to RCT reported in this study. No intact CHL was identified in shoulders with damaged rotator cuff tendons.
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http://dx.doi.org/10.1038/s41598-022-08070-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8913693PMC
March 2022

Visualization of the Third Ventricle, the Future Cavum Septi Pellucidi, and the Cavum Veli Interpositi at 11+3 to 13+6 Gestational Weeks on 3D Transvaginal Ultrasound Including Normative Data.

Ultraschall Med 2022 Feb 25. Epub 2022 Feb 25.

Prenatal Medicine, Kepler University Hospital Med Campus IV, Linz, Austria.

Objectives: To show the development of the third ventricle, commissural plate, future cavum septi pellucidi, and cavum veli interpositi in weeks 12-14 by transvaginal 3D ultrasound.

Methods: This is a prospective transvaginal 3D study carried out to define the third ventricle and the diencephalic midline structures surrounding it. 93 of 387 fetuses in which the commissural plate with the future cavum septi pellucidi, cavum veli interpositi, and the roof of the third ventricle could be well visualized, were selected with the choroid plexus of the third ventricle and the pituitary gland serving as leading structures. In a small number of fetuses, the optic chiasm could also be displayed. In addition, the following measurements were performed: third ventricle craniocaudal and anteroposterior, roof of the third ventricle/cavum veli interpositi, and fcsp.

Results: The sonomorphologic characteristics of the commissural plate, the future cavum septi pellucidi, and the cavum veli interpositi are described IN 9% OF THE FETUSES examined. Measurements of the third ventricle, cavum veli interpositi, and the roof of the third ventricle show the following results: 3rd V cc = 3.895 + 0.091*CRL mm; 3rd V ap = 4.175 + 0.036*CRL mm; CVI ap = 2.223 + 0.029*CRL mm; CVI cc = 0.139 + 0.02*CRL mm.

Conclusion: Transvaginal neurosonography enables visualization and measurement of the normal fetal third ventricle at 12-14 weeks of gestation including visualization of the future cavum septi pellucidi and the cavum veli interpositi. BEFORE USE IN PATIENTS CAN BE CONSIDERED, FURTHER SCIENTIFIC WORK IS REQUIRED.
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http://dx.doi.org/10.1055/a-1683-6141DOI Listing
February 2022

Transverse Relaxation Anisotropy of the Achilles and Patellar Tendon Studied by MR Microscopy.

J Magn Reson Imaging 2022 Feb 5. Epub 2022 Feb 5.

High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria.

Background: T * anisotropy affects the clinical assessment of tendons (magic-angle artifact) and may be a source of T *-misinterpretation.

Purpose: To analyze T *-anisotropy and T *-decay of Achilles and patellar tendons in vitro at microscopic resolution using a variable-echo-time (vTE) sequence.

Study Type: Prospective.

Specimen: Four human Achilles and four patellar tendons.

Field Strength/sequence: A 7 T MR-microscopy; 3D-vTE spoiled-gradient-echo-sequence (T *-mapping).

Assessment: All tendons were measured at 0° and 55° relative to B . Additional angles were measured for one Achilles and one patellar tendon for a total of 11 angles ranging from 0° to 90°. T *-decay was analyzed with mono- and bi-exponential signal fitting. Mono-exponential T *-values (T * ), short and long T *-components (T * , T * ), and the fraction of the short component F of the bi-exponential T *-fit were calculated. T *-decay characteristics were compared with morphological MRI and histologic findings based on a region-of-interest analysis.

Statistical Tests: Akaike information criterion (AIC ), F-test, and paired t-test. A P value smaller than the α-level of 0.05 was considered statistically significant.

Results: T * -values between fiber-to-field angles of 0° and 55° were increased on average from T * (0°) = 1.92 msec to T * (55°) = 29.86 msec (15.5-fold) in the Achilles and T * (0°) = 1.46 msec to T * (55°) = 23.33 msec (16.0-fold) in the patellar tendons. The changes in T * -values were statistically significant. For the whole tendon, according to F-test and AIC , a bi-exponential model was preferred for angles close to 0°, while the mono-exponential model tended to be preferred at angles close to 55°.

Conclusion: MR-microscopy provides a deeper insight into the relationship between T *-decay (mono- vs. bi-exponential model) and tendon heterogeneity. Changes in fiber-to-field angle result in significant changes in T *-values. Thus, we conclude that awareness of T *-anisotropy should be noted in quantitative T *-mapping of tendons to avoid T *-misinterpretation such as a false positive detection of degeneration due to large fiber-to-field angles.

Evidence Level: 2 TECHNICAL EFFICACY: Stage 2.
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http://dx.doi.org/10.1002/jmri.28095DOI Listing
February 2022

Towards Mapping of the Human Brain N-Glycome with Standardized Graphitic Carbon Chromatography.

Biomolecules 2022 01 6;12(1). Epub 2022 Jan 6.

Department of Chemistry, Institute of Biochemistry, Universität für Bodenkultur Wien, Muthgasse 11, A-1190 Vienna, Austria.

The brain N-glycome is known to be crucial for many biological functions, including its involvement in neuronal diseases. Although large structural studies of brain N-glycans were recently carried out, a comprehensive isomer-specific structural analysis has still not been achieved, as indicated by the recent discovery of novel structures with galactosylated bisecting GlcNAc. Here, we present a detailed, isomer-specific analysis of the human brain N-glycome based on standardized porous graphitic carbon (PGC)-LC-MS/MS. To achieve this goal, we biosynthesized glycans with substitutions typically occurring in the brain N-glycome and acquired their normalized retention times. Comparison of these values with the standardized retention times of neutral and desialylated N-glycan fractions of the human brain led to unambiguous isomer specific assignment of most major peaks. Profound differences in the glycan structures between naturally neutral and desialylated glycans were found. The neutral and sialylated N-glycans derive from diverging biosynthetic pathways and are biosynthetically finished end products, rather than just partially processed intermediates. The focus on structural glycomics defined the structure of human brain N-glycans, amongst these are HNK-1 containing glycans, a bisecting sialyl-lactose and structures with fucose and -acetylgalactosamine on the same arm, the so-called LDNF epitope often associated with parasitic worms.
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http://dx.doi.org/10.3390/biom12010085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8774104PMC
January 2022

A biomechanical in-vitro study on an alternative fixation technique of the pubic symphysis for open book injuries of the pelvis.

Injury 2022 Feb 3;53(2):339-345. Epub 2021 Dec 3.

Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria.

Purpose: Implant failure rates remain high after plate fixation in pelvic ring injuries. The aim of this study was to compare an alternative fixation technique with suture-button devices and anterior plate fixation in partially stable open-book injuries.

Material And Methods: We acquired 16 human fresh frozen anatomic pelvic specimens. The sacrospinous, sacrotuberous, and anterior sacroiliac ligaments were bilaterally released, and the pubic symphysis transected to simulate a partially stable open-book (AO/OTA 61-B3.1) injury. The specimens were randomly assigned to the two fixation groups. In the first group two suture-button devices were placed in a criss-crossed position through the symphysis. In second group a six-hole plate with standard 3.5 unlocked bicortical screws was used for fixation. Biomechanical testing was performed on a servo-hydraulic apparatus simulating bilateral stance, as described by Hearn and Varga. Cyclic compression loading with a progressively increasing peak load (0.5 N/cycle) was applied until failure. The failure mode, the load and the number of cycles at failure and the proximal and distal distance of the symphysis during testing were compared.

Results: There was no implant failure in either of the two groups. Failures occurred in nine pelvises (56.2%) at the fixation between the sacrum and the mounting jig and in seven pelvises (43.8%) in the sacroiliac joint. Neither the ultimate load nor the number of cycles at failure differed between the surgical techniques (p = 0.772; p = 0.788, respectively). In the suture button group the mean ultimate load was 874.5 N and the number of cycles at failure was 1907.9. In the plate group values were 826.1 N and 1805.6 cycles, respectively. No significant differences at proximal and distal diastasis of the symphysis were monitored during the whole loading process.

Conclusion: The fixation with suture button implants showed comparable results to anterior plate fixation in open-book injuries of the pelvis.
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http://dx.doi.org/10.1016/j.injury.2021.11.050DOI Listing
February 2022

Delamination in rotator cuff tears: Explanation of etiology through anatomical dissection.

Clin Anat 2022 Mar 22;35(2):194-199. Epub 2021 Nov 22.

Division of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.

The prognostic significance of delaminated rotator cuff tears remains controversial. However, as the surgical goal is to maximize the contact area between layers, the macroscopic appearance of partial delaminated rotator cuff tears is essential. The aim of this anatomical study was to investigate the morphology of delaminated rotator cuff tears. We hypothesized that delamination zones at the intersection of the supraspinatus and infraspinatus tendon fibers are the origin of articular-side degenerative rotator cuff tears. Forty anatomical specimens were evaluated in this study. The supraspinatus and infraspinatus muscles were dissected, the origins were meticulously worked out and followed to their insertions at the humeral head. Fiber exchanges, overlays and delamination zones between the supraspinatus and infraspinatus muscles were photographically documented and measured. Delamination of rotator cuff tears can be classified into articular-side and bursal-side tears. The articular-layer consists of capsuloligamentous tissue, which included the rotator-cable/rotator-crescent complex, the joint capsule and a small part of the supraspinatus tendon. The bursal-side layer represents the tendinous tissue, which consists of the parallel, tendinous parts of the supraspinatus and infraspinatus muscles. Delamination of rotator cuff tears can be classified into articular-side and bursal-side tears. Present model of degenerative tears might explain the high prevalence of articular-side tears, which expand into the rotator-cable/rotator-crescent complex. It may be important for surgeons to incorporate these anatomical findings and considerations into the surgical planning.
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http://dx.doi.org/10.1002/ca.23810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9299111PMC
March 2022

On Measuring Implant Fixation Stability in ACL Reconstruction.

Sensors (Basel) 2021 Oct 6;21(19). Epub 2021 Oct 6.

AO Research Institute Davos, 7270 Davos, Switzerland.

Numerous methods and devices are available for implant fixation in anterior cruciate ligament (ACL) reconstruction. Biomechanical data indicate high variability in fixation stability across different devices. This study aims to provide a better insight into measuring the structural characteristics and mechanical behavior of ACL implant fixations. Fourteen human tibial specimens with reconstructed ACLs were subjected to progressively increasing dynamic loading until failure. The motions of the tibia, the proximal and distal graft ends, as well as the testing frame and actuator, were continuously recorded via a motion tracking system. Significantly higher displacements of the machine actuator (1.0 mm at graft slippage onset, and 12.2 mm at ultimate load) were measured compared to the displacements of the proximal (0.8 and 4.3 mm, respectively) and distal graft (0.1 and 3.4 mm, respectively) ends. The displacements measured at different sites showed significant correlations. The provided data suggest significant and systematic inaccuracies in the stiffness and slippage of the fixation when using machine displacement, as commonly reported in the literature. The assessment of the distal graft displacement excludes the artifactual graft elongation, and most accurately reflects the graft slippage onset indicating clinical failure. Considering the high displacement at the ultimate load, the ultimate load could be used as a standardized variable to compare different fixation methods. However, the ultimate load alone is not sufficient to qualitatively describe fixation stability.
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http://dx.doi.org/10.3390/s21196632DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8513052PMC
October 2021

Thermal Effects during Bone Preparation and Insertion of Osseointegrated Transfemoral Implants.

Sensors (Basel) 2021 Sep 18;21(18). Epub 2021 Sep 18.

Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria.

Background: The preparation of bone for the insertion of an osseointegrated transfemoral implant and the insertion process are performed at very low speeds in order to avoid thermal damages to bone tissue which may potentially jeopardize implant stability. The aim of this study was to quantify the temperature increase in the femur at different sites and insertion depths, relative to the final implant position during the stepwise implantation procedure.

Methods: The procedure for installation of the osseointegrated implant was performed on 24 femoral specimens. In one specimen of each pair, the surgery was performed at the clinically practiced speed, while the speed was doubled in the contralateral specimen. Six 0.075 mm K fine gauge thermocouples (RS Components, Sorby, UK) were inserted into the specimen at a distance of 0.5 mm from the final implant surface, and six were inserted at a distance of 1.0 mm.

Results: Drilling caused a temperature increase of <2.5 °C and was not statistically significantly different for most drill sizes (0.002 < < 0.845). The mean increase in temperature during thread tapping and implant insertion was <5.0 °C, whereas the speed had an effect on the temperature increase during thread tapping.

Conclusions: Drilling is the most time-consuming part of the surgery. Doubling the clinically practiced speed did not generate more heat during this step, suggesting the speed and thus the time- and cost-effectiveness of the procedure could be increased. The frequent withdrawal of the instruments and removal of the bone chips is beneficial to prevent temperature peaks, especially during thread tapping.
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http://dx.doi.org/10.3390/s21186267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8472893PMC
September 2021

Which experimental procedures influence the apparent proximal femoral stiffness? A parametric study.

BMC Musculoskelet Disord 2021 Sep 23;22(1):815. Epub 2021 Sep 23.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, Vienna, 1060, Austria.

Background: Experimental validation is the gold standard for the development of FE predictive models of bone. Employing multiple loading directions could improve this process. To capture the correct directional response of a sample, the effect of all influential parameters should be systematically considered. This study aims to determine the impact of common experimental parameters on the proximal femur's apparent stiffness.

Methods: To that end, a parametric approach was taken to study the effects of: repetition, pre-loading, re-adjustment, re-fixation, storage, and μCT scanning as random sources of uncertainties, and loading direction as the controlled source of variation in both stand and side-fall configurations. Ten fresh-frozen proximal femoral specimens were prepared and tested with a novel setup in three consecutive sets of experiments. The neutral state and 15-degree abduction and adduction angles in both stance and fall configurations were tested for all samples and parameters. The apparent stiffness of the samples was measured using load-displacement data from the testing machine and validated against marker displacement data tracked by DIC cameras.

Results: Among the sources of uncertainties, only the storage cycle affected the proximal femoral apparent stiffness significantly. The random effects of setup manipulation and intermittent μCT scanning were negligible. The 15 deviation in loading direction had a significant effect comparable in size to that of switching the loading configuration from neutral stance to neutral side-fall.

Conclusion: According to these results, comparisons between the stiffness of the samples under various loading scenarios can be made if there are no storage intervals between the different load cases on the same samples. These outcomes could be used as guidance in defining a highly repeatable and multi-directional experimental validation study protocol.
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http://dx.doi.org/10.1186/s12891-021-04656-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8461859PMC
September 2021

[Babysitter nerve transfer from the thenar branch to the deep terminal branch of the ulnar nerve : An option to preserve the intrinsic hand muscles in proximal lesions of the ulnar nerve].

Oper Orthop Traumatol 2021 Oct 17;33(5):392-398. Epub 2021 Sep 17.

Klinisches Labor für bionische Extremitätenrekonstruktion, Universitätsklinik für Plastische, Rekonstruktive und Ästhetische Chirurgie, Medizinische Universität Wien, Wien, Österreich.

Objective: The objective of this surgery is to achieve early reinnervation of the intrinsic hand muscles through axons of the median nerve, preventing irreversible atrophy of the muscle tissue. The nerve transfer is achieved via a babysitter graft, which is sutured end-to-side to the donor as well as the recipient nerve. The procedure is carried out in combination with a proximal reconstruction of the ulnar nerve.

Indications: High-grade lesions of the ulnar nerve without spontaneous regeneration, particularly when lesions are located proximally and/or when patients present late.

Contraindications: Irreversible denervation of the intrinsic muscles; weakness or palsy of the thenar branch.

Surgical Technique: The approach is taken through a longitudinal incision over the volar wrist. The deep branch of the ulnar nerve as well as the thenar branch of the median nerve are visualized after transection of the flexor retinaculum. An autologous graft is then placed between the two nerves, sutured to the donor (thenar branch) as well as the recipient nerve (ulnar deep branch) via an epineural window in an end-to-side manner. This facilitates timely regeneration of motor axons from the median nerve into the intrinsic muscles, thereby preventing irreversible degeneration. Through the end-to-side nerve coaptation, damage to the donor nerve is reduced to a minimum. At the same time reconstruction of the ulnar nerve is performed proximally to the lesion, facilitating original reinnervation of the intrinsic muscles at a later time.

Postoperative Management: Postoperatively, Penrose drains are placed and a sterile hand dressing is applied. Drain removal and dressing change are performed on the first day, suture removal after 2 weeks. Physical therapy for mobility of the joints can be started as early as 1 week after surgery. After the first signs of motor and/or sensory reinnervation, a targeted retraining of daily skills should be initiated.

Results: This procedure has so far been reported on three patients with high-grade ulnar nerve injury. After a follow-up duration of 6 years, each achieved muscle strength of ≥ M3, with good to excellent overall regeneration according to the modified Bishop rating scale.
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http://dx.doi.org/10.1007/s00064-021-00733-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8460543PMC
October 2021

Quantitative Anatomic Comparison of Microsurgical Transcranial, Endoscopic Endonasal, and Transorbital Approaches to the Spheno-Orbital Region.

Oper Neurosurg (Hagerstown) 2021 11;21(6):E494-E505

Division of Neurosurgery, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy.

Background: The spheno-orbital region (SOR) is a complex anatomic area that can be accessed with different surgical approaches.

Objective: To quantitatively compare, in a preclinical setting, microsurgical transcranial approaches (MTAs), endoscopic endonasal transpterygoid approach (EEA), and endoscopic transorbital approaches (ETOAs) to the SOR.

Methods: These approaches were performed in 5 specimens: EEA, ETOAs (superior eyelid and inferolateral), anterolateral MTAs (supraorbital, minipterional, pterional, pterional-transzygomatic, and frontotemporal-orbitozygomatic), and lateral MTAs (subtemporal and subtemporal transzygomatic). All specimens underwent high-resolution computed tomography; an optic neuronavigation system with dedicated software was used to quantify working volume and exposed area for each approach. Mixed linear models with random intercepts were used for statistical analyses.

Results: Anterolateral MTAs offer a direct route to the greater wings (GWs) and lesser wings (LWs); only they guarantee exposure of the anterior clinoid. Lateral MTAs provide access to a large area corresponding to the GW, up to the superior orbital fissure (SOF) anteriorly and the foramen rotundum medially. ETOAs also access the GW, close to the lateral portion of SOF, but with a different angle of view as compared to lateral MTAs. Access to deep and medial structures, such as the lamina papyracea and the medial SOF, is offered only by EEA, which exposes the LW and GW only to a limited extent.

Conclusion: This is the first study that offers a quantitative comparison of the most used approaches to SOR. A detailed knowledge of their advantages and limitations is paramount to choose the ideal one, or their combination, in the clinical setting.
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http://dx.doi.org/10.1093/ons/opab310DOI Listing
November 2021

The intercondylar fossa-A narrative review.

Clin Anat 2022 Jan 24;35(1):2-14. Epub 2021 Aug 24.

Department of Radiology and Image Guided Therapy, Medical University of Vienna, Vienna, Austria.

The intercondylar fossa ("intercondylar notch," IN) is a groove at the distal end of the femur, housing important stabilizing structures: cruciate ligaments and meniscofemoral ligaments. As the risk for injury to these structures correlates with changes to the IN, exact knowledge of its morphology, possible physiological and pathological changes and different approaches for evaluating it are important. The divergent ways of assessing the IN and the corresponding measurement methods have led to various descriptions of its possible shapes. Ridges at the medial and lateral wall are considered clinically important because they can help with orientation during arthroscopy, whereas ridges at the osteochondral border could affect the risk of ligament injury. Changes related to aging and sex differences have been documented, further emphasizing the importance of individual assessment of the knee joint. Overall, it is of the utmost importance to remember the interactions between the osseous housing and the structures within.
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http://dx.doi.org/10.1002/ca.23773DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9291140PMC
January 2022

Resonance frequency analysis of implants placed in condensed bone.

Clin Oral Implants Res 2021 Oct 1;32(10):1200-1208. Epub 2021 Sep 1.

Department of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.

Objectives: Resonance frequency analysis (RFA) is used to monitor implant stability. Its output, the Implant Stability Quotient (ISQ), supposedly correlates with insertion torque, a common measurement of primary stability. However, the reliability of RFA in condensed bone remains unclear.

Material And Methods: In this human cadaver study in edentulous jaws and fresh extraction sockets, implants were inserted using a split-mouth approach into condensed or untreated bone. Mean ISQ, peak insertion torque, and pre- and postoperative bone volume fractions (BV/TV) were assessed.

Results: In edentulous jaws, insertion torque and ISQ correlated both in untreated (r = 0.63, p = 0.02) and in condensed (r = 0.82, p  < 0.01) bone. In extraction sockets, insertion torque and ISQ only correlated in untreated (r = 0.78, p < 0.01), but not in condensed bone (r = 0.15, p = 0.58). In all edentulous jaws, preoperative BV/TV correlated with insertion torque (r = 0.90, p < 0.0001), ISQ (r = 0.64, p < 0.001), and changes in BV/TV (r = -0.71, p < 0.01). In all extraction sockets, preoperative BV/TV did not correlate with either insertion torque (r = 0.33, p = 0.15), ISQ (r = 0.38, p = 0.09), or changes in BV/TV (r = -0.41, p = 0.09). Joint analysis identified preoperative BV/TV as a predictor of postoperative BV/TV (p < 0.001), insertion torque (p < 0.001), and ISQ (p < 0.001).

Conclusions: RFA is feasible for monitoring stability after late implant placement into condensed bone, but not after immediate placement into condensed fresh extraction sites.
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http://dx.doi.org/10.1111/clr.13817DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9292279PMC
October 2021

[Peroneal tendon pathologies : From the diagnosis to treatment].

Orthopade 2021 Jul 23;50(7):589-604. Epub 2021 Jun 23.

Universitätsklinik für Orthopädie und Unfallchirurgie, Klinische Abteilung für Orthopädie, Medizinische Universität Wien, Währinger Gürtel 18-20, 1090, Wien, Österreich.

Peroneal tendon pathologies are rare but often underdiagnosed. There may be an association with chronic lateral ankle instability as well as with varus hindfoot alignment. Pathologies of the tendons fall into three categories: tendinitis and tenosynovitis, tendon ruptures and tears, and tendon subluxation and dislocation. Magnetic resonance imaging is the standard method for radiological assessment; however, the diagnosis and treatment are based primarily on patient history and clinical examination. A primary conservative treatment can be attempted, except for peroneal tendon dislocations in professional athletes. Surgical treatment should be targeted to the underlying pathology and can accordingly vary from tendoscopic synovectomy to anatomic repair of the superior peroneal retinaculum with deepening of the retromalleolar groove. Postoperative results show high patient satisfaction and low reluxation rates.
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http://dx.doi.org/10.1007/s00132-021-04116-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8241798PMC
July 2021

Retroesophageal right subclavian artery associated with a bicarotid trunk and an ectopic origin of vertebral arteries.

Surg Radiol Anat 2021 Sep 15;43(9):1491-1495. Epub 2021 Apr 15.

Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, V.le Europa 11, 25123, Brescia, Italy.

A rare branching pattern of the aortic arch in a female cadaver is reported. An aberrant right subclavian artery originated from the distal part of the aortic arch and following a retroesophageal course was recognized. Next to it, from the left to the right, the left subclavian artery and a short bicarotid trunk originating the left and the right common carotid artery were recognized. An unusual origin of the vertebral arteries was also identified. The left vertebral artery originated directly from the aortic arch, whereas the right vertebral artery originated directly from the right common carotid artery. Retroesophageal right subclavian artery associated with a bicarotid trunk and ectopic origin of vertebral arteries represents an exceptional and noteworthy case.
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http://dx.doi.org/10.1007/s00276-021-02746-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8408090PMC
September 2021

Comparison of Thiel preserved, fresh human, and animal liver tissue in terms of mechanical properties.

Ann Anat 2021 Jul 6;236:151717. Epub 2021 Mar 6.

Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, 1060 Wien, Austria. Electronic address:

Background: In medical training and research fresh human tissue is often replaced by preserved human or fresh animal tissue, due to availability and ethical reasons. Newer preservation approaches, such as the Thiel method, promise more realistic mechanical properties than conventional formaldehyde fixation. Concerning animal substitute material, porcine and bovine tissue is often chosen, as it is easily obtainable and certain similarity to human tissue is assumed. However, it has not been thoroughly investigated how Thiel preservation changes non-linear and viscoelastic behaviour of soft organ tissues. Furthermore, differences in these properties between animal tissue and human tissue have not been previously corroborated.

Methods: We conducted ramp and relaxation tensile tests on fresh human and Thiel preserved hepatic tissue, extracting strain-specific elastic moduli, and viscoelastic properties. The results for fresh human liver were then compared to corresponding results for Thiel preserved liver, as well as previously published results for porcine and bovine liver.

Results: Our results showed that Thiel preservation seems to be associated with increased stiffness as well as decreased viscoelastic damping behaviour. Porcine liver was stiffer than human liver with similar viscoelastic properties. Bovine liver exhibited similar stiffness as human liver, however lower viscoelastic damping.

Conclusions: The differences between human and animal liver tissue, concerning their mechanical properties, can be explained by their characteristic histology. Changes in mechanical properties due to Thiel preservation might stem from altered protein cross-linking and dehydration. The results illustrate that appropriate materials for medical training systems must be selected based on which mechanical properties are relevant for the respective application.
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http://dx.doi.org/10.1016/j.aanat.2021.151717DOI Listing
July 2021

Transorbital endoscopic approaches to the skull base: a systematic literature review and anatomical description.

Neurosurg Rev 2021 Oct 22;44(5):2857-2878. Epub 2021 Jan 22.

Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padua, Padua, Italy.

Transorbital endoscopic approaches are increasing in popularity as they provide corridors to reach various areas of the ventral skull base through the orbit. They can be used either alone or in combination with different approaches when dealing with the pathologies of the skull base. The objective of the current study is to evaluate the surgical anatomy of transorbital endoscopic approaches by cadaver dissections as well as providing objective clinical data on their actual employment and morbidity through a systematic review of the current literature. Four cadaveric specimens were dissected, and step-by-step dissection of each endoscopic transorbital approach was performed to identify the main anatomic landmarks and corridors. A systematic review with pooled analysis of the current literature from January 2000 to April 2020 was performed and the related studies were analyzed. Main anatomical landmarks are presented based on the anatomical study and systematic review of the literature. With emphasis on the specific transorbital approach used, indications, surgical technique, and complications are reviewed through the systematic review of 42 studies (19 in vivo and 23 anatomical dissections) including 193 patients. In conclusion, transorbital endoscopic approaches are promising and appear as feasible techniques for the surgical treatment of skull base lesions. Surgical anatomy of transorbital endoscopic approaches can be mastered through knowledge of a number of anatomical landmarks. Based on data available in the literature, transorbital endoscopic approaches represent an important complementary that should be included in the armamentarium of a skull base team.
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http://dx.doi.org/10.1007/s10143-020-01470-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8490260PMC
October 2021

Maximum Ankle Plantarflexion and Dorsiflexion Allow for Optimal Arthroscopic Access to the Talar Dome: An Anatomic 3-Dimensional Radiography Study.

Arthroscopy 2021 04 25;37(4):1245-1257. Epub 2020 Dec 25.

Division of Orthopedics, Department of Orthopedics and Trauma-Surgery, Medical University of Vienna, Vienna, Austria.

Purpose: (1) to improve the comprehension of the topographical position of the talar dome beneath the inferior articular surface of the tibia and, (2) to illustrate the changes of possible access to the articular surface of the talar dome during arthroscopic treatment of talar osteochondral defects in an anatomical model.

Methods: Twenty matched pairs (n = 40) of anatomical ankle specimen were used. All specimens were mounted in a standardized fashion, 3-dimensional radiography was performed in 4 defined positions (maximum dorsiflexion, neutral position, noninvasive distraction, and maximum plantarflexion). All radiographs were analyzed and statistically compared.

Results: Anterior accessibility was highest in maximum plantarflexion (medial: 49.20 ± 9.86%, lateral: 48.19 ± 8.85%), followed by non-invasive distraction (medial: 33.60 ± 7.96%, lateral: 31.98 ± 8.30%). Neutral position (medial: 19.34 ± 6.90%, lateral: 17.54 ± 6.63%) and dorsiflexion (medial: 15.36 ± 5.03%, lateral: 13.88 ± 4.33%) were not able to significantly increase accessibility. Posterior accessibility was greatest in maximum dorsiflexion (medial: 56.69 ± 9.65%, lateral: 46.82 ± 8.36%), followed by neutral position of the ankle joint (medial: 40.95 ± 8.28%, lateral: 31.06 ± 6.92%). Noninvasive distraction (medial: 31.41 ± 8.18%, lateral: 22.99 ± 7.63%) was still significantly better than plantarflexion (medial: 14.54 ± 5.10%, lateral: 13.89 ± 3.14%) and slightly increased accessibility to the talar dome. Medially, a central area of 5.89 ± 9.76% was accessible by maximum plantarflexion and maximum dorsiflexion from anterior and posterior, respectively, laterally a central blind spot of 4.99 ± 8.61% was detected.

Conclusions: From an anatomical point of view, maximum joint positions of the ankle (i.e., plantarflexion and dorsiflexion) allow for better access to the talar dome in anterior and posterior ankle arthroscopy. Noninvasive distraction may increase accessibility in anterior approaches, but has no benefit from posterior.

Clinical Relevance: This study provides insight into the morphology of the ankle joint in a standardized laboratory setup and illustrates the influence of different surgically relevant ankle joint positions. The presented data allow for better preoperative planning for the arthroscopic treatment of talar osteochondral defects.
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http://dx.doi.org/10.1016/j.arthro.2020.12.207DOI Listing
April 2021

The sellar barrier on preoperative imaging predicts intraoperative cerebrospinal fluid leak: a prospective multicenter cohort study.

Pituitary 2021 Feb 12;24(1):27-37. Epub 2020 Sep 12.

LINT, Facultad de Medicina, Universidad Nacional de Tucumán, Lamadrid 875, San Miguel de Tucumán, Tucumán, Argentina.

Background: The type of sellar barrier observed between a pituitary tumor and cerebrospinal fluid (CSF) on preoperative magnetic resonance imaging (MRI) may predict intraoperative CSF leak during endonasal pituitary surgery. This is the first multicentric prospective cohort trial to study the sellar barrier concept and CSF leak rate during endoscopic pituitary surgery.

Methods: This multi-center, international study enrolled patients operated for pituitary adenomas via fully endoscopic endonasal surgery over a period of 4 months. The independent variable was the subtype of sellar barrier observed on preoperative MRI (strong, mixed or weak); the dependent variable was the presence of an intraoperative CSF leak. The primary goal was to determine the association between a particular type of sellar barrier and the risk of intraoperative CSF leak. Appropriate statistical methods were then applied for data analysis.

Results: Over the study period, 310 patients underwent endoscopic endonasal surgery for pituitary tumor. Preoperative imaging revealed a weak sellar barrier in 73 (23.55%), a mixed sellar barrier in 75 (24.19%), and a strong sellar barrier in 162 (52.26%) patients. The overall rate of intraoperative CSF leak among all patients was 69 (22.26%). A strong sellar-type barrier was associated with significantly reduced rate of intraoperative CSF leak (RR = 0.08; 95% CI 0.03-0.19; p < 0.0001), while a weak sellar barrier associated with higher rates of CSF leak (RR = 8.54; 95% CI 5.4-13.5; p < 0.0001).

Conclusions: The preoperative MRI of pituitary patients can suggest intraoperative CSF leak rates, utilizing the concept of the sellar barrier. Patients with a weak sellar barrier carry a higher risk for an intraoperative CSF leak, whereas a strong sellar barrier on MRI seems to mitigate intraoperative CSF leak. We propose that preoperatively assessment of the sellar barrier can prepare surgeons for intraoperative CSF leak repair.
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http://dx.doi.org/10.1007/s11102-020-01082-8DOI Listing
February 2021

The intraspinal arterial collateral network: a new anatomical basis for understanding and preventing paraplegia during aortic repair.

Eur J Cardiothorac Surg 2021 01;59(1):137-144

Department of Cardiovascular Surgery, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany.

Objectives: The anatomical distribution pattern of epidural intraspinal arteries is not entirely understood but is likely to substantially impact maintaining perfusion during segmental artery sacrifice when treating acute and chronic thoraco-abdominal aortic diseases. We investigated the anatomical distribution pattern of intraspinal arteries.

Methods: Twenty fresh, non-embalmed cadaveric human bodies were studied. Anatomical dissection and investigation of the epidural arterial network were performed according to a standardized protocol. We used a generalized mixed linear model to test whether the presence probability for certain vessels differed between vertebrae/segments.

Results: There was craniocaudal continuity of all ipsilateral longitudinal connections from T1 to L5 by the anterior radicular artery. The mean [±standard deviation (SD)] number of transverse anastomoses was 9.7 ± 2.1. The presence probability of transverse anastomoses along the spine was different between vertebrae (P < 0.0001). There were 2 distribution peaks along the spine: 1 peak around T4-T6 and 1 around T11. The mean (±SD) number of thoracic and lumbar anterior radiculomedullary arteries (ARMAs) was 3.0 ± 1.1. The probability of the presence of ARMAs along the spine was different for each vertebral segment (P < 0.0001). Between ARMAs there were gaps of up to a maximum of 9 vertebrae. All Adamkiewicz arteries were located caudally to T7. The median segment of the Adamkiewicz presence was T10/11.

Conclusions: The epidural collateral network shows craniocaudal continuity. The number of transverse anastomoses is high. The number of ARMAs is low, and there is considerable variation in their distribution and offspring, which is highly likely to impact perfusion during segmental artery sacrifice when treating thoraco-abdominal aortic disease.
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http://dx.doi.org/10.1093/ejcts/ezaa227DOI Listing
January 2021

The tibialis posterior tendon footprint: an anatomical dissection study.

J Foot Ankle Res 2020 May 19;13(1):25. Epub 2020 May 19.

Center for Anatomy and Cell Biology, Division of Anatomy, Medical University of Vienna, Vienna, Austria.

Background: The tibialis posterior tendon (TPT) is the main dynamic stabilizer of the medial longitudinal arch of the foot. Especially in adult acquired flatfoot deformity (AAFD) the TPT plays a detrimental role. The pathology and function of the tendon have been extensively investigated, but knowledge of its insertional anatomy is paramount for surgical procedures. This study aimed to analyze the complex distal footprint anatomy of the TPT.

Methods: Forty-one human anatomical specimens were dissected and the distal TPT was followed to its bony footprints. After tendon removal the footprints were marked with ink. Standardized photographs were taken and consecutively analyzed by digital imaging measurements. Footprint length, width, area of insertion, location, and shape was studied regarding the main insertion at the navicular bone.

Results: All specimens had the main TPT insertion at the navicular bone (41/41, 100%). Sixty-three percent of navicular TPT insertions were located at the plantar aspect. The mean navicular footprint measured 12.1 mm × 6.9 mm in length and width, respectively. The tendon further spread into several slips which anchored the tibialis posterior deep in the plantar arch. TPT insertions were highly variable with an involvement of up to eight distinct bony footprints in the mid- and hindfoot. The second most common additional footprint was the lateral cuneiform (93% of dissected feet), followed by the medial cuneiform (80%), the metatarsal bases [1-5] (80%), the cuboid (46%), the intermediate cuneiform (19%), and the calcaneus (12%).

Conclusions: The present study adds to current knowledge on the footprint anatomy of the TPT. Based on the findings of this study we advocate a plantar location of flexor digitorum longus tendon transfer in flexible AAFD in order to restore the anatomical lever and insertion of the TPT.
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http://dx.doi.org/10.1186/s13047-020-00392-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7236122PMC
May 2020

Peroneus brevis as source of instability in Jones fracture fixation.

Int Orthop 2020 07 5;44(7):1409-1416. Epub 2020 May 5.

Department of Orthopedics and Trauma Surgery, Division of Orthopedics, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, 1090, Austria.

Purpose: Intramedullary screw fixation is currently considered the gold standard treatment for Jones fractures in the athlete. Besides biological factors (i.e., poor vascularization), mechanical instability induced by the pull of the peroneus brevis tendon (PBT) contributes to deficient Jones fracture healing. This biomechanical study aimed to simulate loads induced by the PBT at the fifth metatarsal and to compare the stability of two intramedullary screw constructs in a Jones fracture fixation model.

Methods: Jones fractures were created in 24 human paired specimens, and fixation was achieved with either a solid Jones fracture specific screw (JFXS) (Jones Screw; Arthrex Inc., Naples FL, USA) or a cannulated headless compression screw (HCS) (HCS; DePuySynthes, Solothurn, Switzerland). The PBT was fixed to a mechanical load frame by the use of a cryoclamp. Constructs were loaded in tension for 1000 cycles, followed by an ultimate load test. Construct failure was defined by exceeding 10° of dorsal angulation.

Results: Preliminary failure occurred more often in HCS constructs (33%) compared to JFXS constructs (0%) (P = 0.044). Mean tensile load to failure reached 123.8 ± 91.4 N in the JFXS group and 91.5 ± 62.2 N in the HCS group (P = 0.337). The mean slope of the load-displacement curve was 24.2 ± 10.4 N/mm for JFXS constructs and 24.7 ± 5.5 N/mm for HCS constructs, respectively (P = 0.887).

Conclusion: This is the first study evaluating the effect of PBT pull on the mechanical stability of Jones fracture fixation. Higher preliminary failure rates of HCS were found under cyclic loading conditions compared to JFXS.
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http://dx.doi.org/10.1007/s00264-020-04581-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306048PMC
July 2020

Anatomical Considerations of Intramedullary Humeral Nailing and Lengthening.

J Clin Med 2020 Mar 16;9(3). Epub 2020 Mar 16.

Department of Orthopedics and Trauma-Surgery, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.

Intramedullary lengthening, in cases of extensive humeral shortening, offers the advantages of preventing external-fixator-associated problems. The humeral cavity, as the main parameter in nailing, however, has been neglected in recent literature. It was hypothesized that available implants might be too large and therefore increase the risk of intraoperative fractures. The aim of this cross-sectional study was to describe the humeral canal and how it might affect the choice of implant and the surgical approach. Thirty humeri (15 female, 15 male) from clinical patients and anatomical specimens were studied. Specifically, the medullary cavity width (MCW), cortical thickness (CoT), and the course of the medullary canal were examined. The smallest MCW diameters were found at the distal third of the humeral shaft with mean diameters of 10.15 ± 1.96 mm. CoTs of female humeri were significantly smaller than those of male humeri ( < 0.001). The mean angles of the pro- and recurvatum were 4.01 ± 1.68° and 10.03 ± 2.25°, and the mean valgus bending was 3.37 ± 1.58°. Before implanting a straight lengthening nail into a doubly curved humerus, X-rays and, in selected cases, CT-scans should be performed. The unique size and course of the humeral canal favors an antegrade approach in cases of intramedullary lengthening.
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http://dx.doi.org/10.3390/jcm9030806DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141300PMC
March 2020
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