Journal: Journal of Experimental Orthopaedics

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SpringerOpen

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2197-1153

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2022 - 20233
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Publications 1 - 3 of 3
  • Finite element analysis of medial closing and lateral opening wedge osteotomies of the distal femur in relation to hinge fractures
    Item type: Journal Article
    Meisterhans, Michel; Flury, Andreas; Zindel, Christoph; et al. (2023)
    Journal of Experimental Orthopaedics
    PurposeIntraoperative hinge fractures in distal femur osteotomies represent a risk factor for loss of alignment and non-union. Using finite element analysis, the goal of this study was to investigate the influence of different hinge widths and osteotomy corrections on hinge fractures in medial closed-wedge and lateral open-wedge distal femur osteotomies.MethodsThe hinge was located at the proximal margin of adductor tubercle for biplanar lateral open-wedge and at the upper border of the lateral femoral condyle for biplanar medial closed-wedge distal femur osteotomies, corresponding to optimal hinge positions described in literature. Different hinge widths (5, 7.5, 10 mm) were created and the osteotomy correction was opened/closed by 5, 7.5 and 10 mm. Tensile and compressive strain of the hinge was determined in a finite element analysis and compared to the ultimate strain of cortical bone to assess the hinge fracture risk.ResultsDoubling the correction from 5 to 10 mm increased mean tensile and compressive strain by 50% for lateral open-wedge and 48% for medial closed-wedge osteotomies. A hinge width of 10 mm versus 5 mm showed increased strain in the hinge region of 61% for lateral open-wedge and 32% for medial closed-wedge osteotomies. Medial closed-wedge recorded a higher fracture risk compared to lateral open-wedge osteotomies due to a larger hinge cross-section area (60-67%) for all tested configurations. In case of a 5 mm hinge, medial closed-wedge recorded 71% higher strain in the hinge region compared to lateral open-wedge osteotomies.ConclusionDue to morphological features of the medial femoral condyle, finite element analysis suggests that lateral-open wedge osteotomies are the preferable option if larger corrections are intended, as a thicker hinge can remain without an increased hinge fracture risk.
  • Deepening trochleoplasty may dramatically increase retropatellar contact pressures- a pilot study establishing a finite element model
    Item type: Journal Article
    Kaiser, Dominik; Götschi, Tobias; Bachmann, Elias; et al. (2022)
    Journal of Experimental Orthopaedics
  • Posterior stability of the shoulder depends on acromial anatomy: a biomechanical study of 3D surface models
    Item type: Journal Article
    Hochreiter, Bettina; Beeler, Silvan; Hofstede, Simon; et al. (2023)
    Journal of Experimental Orthopaedics
    Purpose Primary glenohumeral osteoarthritis is commonly associated with static posterior subluxation of the humeral head. Scapulae with static/dynamic posterior instability feature a superiorly and horizontally oriented acromion. We investigated whether the acromion acts as a restraint to posterior humeral translation. Methods Five three-dimensional (3D) printed scapula models were biomechanically tested. A statistical shape mean model (SSMM) of the normal scapula of 40 asymptomatic shoulders was fabricated. Next, a SSMM of scapular anatomy associated with posterior subluxation was generated using data of 20 scapulae (“B1”). This model was then used to generate three models of surgical correction: glenoid version, acromial orientation, and acromial and glenoid orientation. With the joint axially loaded (100N) and the humerus stabilized, an anterior translation force was applied to the scapula in 35°, 60° and 75° of glenohumeral flexion. Translation (mm) was measured. Results In the normal scapula, the humerus translates significantly less to contact with the acromion compared to all other configurations (p < .000 for all comparisons; i.e. 35°: “normal” 8,1 mm (± 0,0) versus “B1” 11,9 mm (± 0,0) versus “B1 Acromion Correction” 12,2 mm (± 0,2) versus “B1 Glenoid Correction” 13,3 mm (± 0,1)). Restoration of normal translation was only achieved with correction of glenoid and acromial anatomy (i.e. 75°: “normal” 11 mm (± 0,8) versus “B1 Acromion Correction” 17,5 mm (± 0,1) versus “B1 Glenoid Correction” 19,7 mm (± 1,3) versus “B1 Glenoid + Acromion Correction” 11,5 mm (± 1,1)). Conclusions Persistence or recurrence of static/dynamic posterior instability after correction of glenoid version alone may be related to incomplete restoration of the intrinsic stability that is conferred by a normal acromial anatomy.
Publications 1 - 3 of 3