Biomechanical analysis of a novel clavicular hook plate for the treatment of acromioclavicular joint dislocation: A finite element analysis

Optimizing hook implantation angle of the clavicular hook plate: a cadaveric study

PURPOSE

While Clavicle hook plates have demonstrated favorable results regarding bone and shoulder function, their design can potentially lead to complications due to pressure concentration at the plate's tip. This study aims to investigate the impact of different hook implantation angles on the contact surface area between the hook plate and acromion, with the goal of minimizing mismatch and maximizing contact surface area.

METHODS

Twenty soft shoulder cadavers were included in the study, and the contact surface area of the hook plate was measured in different positions based on the hook implantation angle.

RESULTS

The results showed variations in compatibility, width, and length of the contact surface area depending on the hook implantation angle and the medial or lateral row placement. The lateral row generally demonstrated superior compatibility (84.0% vs 46.67%, p-value < 0.001), with a broader contact area (3.55 ± 0.08 mm vs 3.09 ± 0.10 mm, p-value = 0.004) and a longer contact area (7.36 ± 0.19 mm vs 5.10 ± 0.23 mm, p-value < 0.001) at specific angles. A detailed analysis of the lateral position revealed that the zero angle of implantation resulted in the greatest contact surface area, measuring 3.91 ± 0.70 mm in width (p value = 0.083) and 8.85 ± 1.24 mm in length (p value < 0.001).

CONCLUSION

Placing the hook laterally and at the zero position according to the hook implantation angle can maximize contact surface area, may reduce stress concentration, and minimize complications in hook plate fixation. Further research and consideration of anatomical variations are warranted to refine the placement technique and enhance patient outcomes.

LEVEL OF EVIDENCE

Level V evidence.

QCT-based 3D finite element modeling to assess patient-specific hip fracture risk and risk factors

Early assessment of hip fracture risk may play a critical role in designing preventive mechanisms to reduce the occurrence of hip fracture in geriatric people. The loading direction, clinical, and morphological variables play a vital role in hip fracture. Analyzing the effects of these variables helps predict fractures risk more accurately; thereby suggesting the critical variable that needs to be considered. Hence, this work considered the fall postures by varying the loading direction on the coronal plane (α) and on the transverse plane (β) along with the clinical variables-age, sex, weight, and bone mineral density, and morphological variables-femoral neck axis length, femoral neck width, femoral neck angle, and true moment arm. The strain distribution obtained via finite element analysis (FEA) shows that the angle of adduction (α) during a fall increases the risk of fracture at the greater trochanter and femoral neck, whereas with an increased angle of rotation (β) during the fall, the FRI increases by ∼1.35 folds. The statistical analysis of clinical, morphological, and loading variables (αandβ) delineates that the consideration of only one variable is not enough to realistically predict the possibility of fracture as the correlation between individual variables and FRI is less than 0.1, even though they are shown to be significant (p<0.01). On the contrary, the correlation (R2=0.48) increases as all variables are considered, suggesting the need for considering different variables fork predicting FRI. However, the effect of each variable is different. While loading, clinical, and morphological variables are considered together, the loading direction on transverse plane (β) has high significance, and the anatomical variabilities have no significance.

Effect of different loads on the shoulder in abduction postures: a finite element analysis

Load can change the mechanical environment of dynamic and static stable structures of the shoulder joint, increase the risk of tissue damage and affect the stability of the shoulder joint, but its biomechanical mechanism is still unclear. Therefore, a finite element model of the shoulder joint was constructed to analyze the mechanical index changes of shoulder joint abduction under different loads. The stress of the articular side on the supraspinatus tendon was higher than that of the capsular side, with a maximum difference of 43% due to the increased load. For the deltoid muscle and glenohumeral ligaments, increases in stress and strain were obvious in the middle and posterior deltoid muscles and inferior glenohumeral ligaments. The above results indicate that load increases the stress difference between the articular side and the capsular side on the supraspinatus tendon and increases the mechanical indices of the middle and posterior deltoid muscles, as well as the inferior glenohumeral ligament. The increased stress and strain in these specific sites can lead to tissue injury and affect the stability of the shoulder joint.

Finite element analysis of a novel anatomical locking plate for scapular neck fracture

OBJECTIVES

Reconstruction plates (RPs) are commonly used in scapular neck fractures (SNFs): however, RPs have many defects. In this study, we evaluated a newly designed scapular neck anatomical locking compression plate (SNALCP).

METHODS

An SNF finite element model (Miller-type IIB) was constructed. Plates were subsequently implanted into the scapula and fixed with screws that were grouped according to the plate used: SNALCP (A) and RP (B). Finally, loads were applied to record and analyze performance.

RESULTS

Under lateral, anteroposterior, and vertical compression loads, the maximum von Mises stresses on the scapula and implants of group A were smaller than those of group B. There were some differences in stress distribution between the two groups.

CONCLUSIONS

SNALCP can effectively reduce the stress of the scapula and implant, making stress distribution more uniform and continuous, and has mechanical conduction advantages. Compared to RP, it provides improved stability and more reliable fixation.

Dual plate has better biomechanical stability than hook plate or superior single plate for the fixation of unstable distal clavicle fractures: a finite element analysis

INTRODUCTION

A variety of surgical techniques have been addressed for distal clavicle fractures, while none of these is considered to be gold standard fixation. Currently, dual plate fixation has been proposed and achieved satisfying clinical results. However, the biomechanical study about dual plate technique in treating unstable distal clavicle fractures is limited. Thus, the purpose of this study was to investigate the biomechanical properties of this technique by finite element analysis.

MATERIALS AND METHODS

A geometry model of distal clavicle fractures was combined with hook plate, superior single plate and dual plate, respectively, to simulate the implant fixation process. Two loading conditions and two boundary conditions were applied in the finite element models following a mesh convergence test. The stress distribution was observed, and peak von Mises stress and maximum displacement were used as indexes for analysis.

RESULTS

The dual plate model showed the highest clavicle stress (13.1 MPa), but lowest fixation stress (18.9 MPa) compared to the hook plate and superior single model. In regarded to stability, dual plate model exhibited a minimum displacement with only 0.099 mm.

CONCLUSIONS

Dual plate fixation has better biomechanical stability with lower risk of implant failure. Thus, dual plate fixation is an alternative technique for unstable distal clavicle fracture. The complication of peri-implant fracture of dual plate technique should also be cautious in clinical practice, and more clinical evidence is needed.

The stress and strain pattern in the ligaments of the acromioclavicular joint using a quasi-static model

BACKGROUND

The precise role of the acromioclavicular and coracoclavicular ligaments during shoulder motion is unclear. We evaluate changes in the stress-strain distribution of the acromioclavicular joint's ligaments during different shoulder passive motion positions.

METHODS

A 3D acromioclavicular joint model was reconstructed. A constitutive hyperelastic model was used for the ligaments. The kinematics of the shoulder girdle was taken to simulate shoulder abduction (Motion 1) and horizontal adduction (Motion 2). A computer-generated quasi-static and non-linear finite element model was used to predict the 3D stress-strain distribution pattern of the acromioclavicular ligament and the coracoclavicular ligament complex.

FINDINGS

In motion 1, from 20 to 90° the peak von Mises stress was found in the conoid (4.14 MPa) and the anteroinferior bundle (2.46 MPa), while from 90 to 120° it was found in the conoid and the trapezoid. However, there were no significant differences between the mean stress values between anteroinferior bundle and trapezoid throughout the motion (p = 0.98). In Motion 2, from 20 to 80° the maximum equivalent elastic strain was found in the anteroinferior bundle (0.68 mm/mm) and the conoid (0.57 mm/mm), while from 80 to 100° it was higher in the conoid (0.88 mm/mm) than in the anteroinferior bundle (0.77 mm/mm).

INTERPRETATION

The coracoclavicular ligament complex demonstrated a high stress-strain concentration during simulated passive shoulder abduction. Additionally, it was shown that the acromioclavicular ligament plays an important role in joint restraint during passive horizontal adduction, changing the primary role with the trapezoid and conoid at different motion intervals.

Concomitant coracoid base fracture and acromioclavicular joint disruption: A series of patients treated with a clavicle hook plate and review of the literature

INTRODUCTION

Concomitant acromioclavicular joint (ACJ) disruptions with coracoid base fractures are rare high energy injuries. The management of these injuries can be challenging. The aim of this study is to assess the functional and radiographic outcomes of a retrospective case series of patients presenting with concomitant ACJ and coracoid base injuries managed with a clavicle hook plate with subsequent hardware removal at a later stage.

METHODS

Six patients were identified for inclusion in the study. Radiographic and clinical data were available which allowed for collection of demographic information as well as classification of the fractures. Telephone consultation with patients allowed for collection of functional scores which included the Oxford shoulder score (OSS), QuickDASH (Q-DASH), Euroqol-5 Dimension (EQ-5D) and the SF-12 score.

RESULTS

All patients were male with a mean age of 39.8 years and a median follow-up period of 34 months. All patients underwent a successful operative procedure with a median time to union of 3.75 months. Good functional outcomes were reported by all patients: mean OSS 45.0, mean Q-DASH 4.8, mean EQ-VAS 82.8 and encouraging SF-12 scores (mean PCS 56.0, mean MCS 56.4).

CONCLUSION

The use of a lateral clavicle hook plate can achieve good healing and functional outcomes when managing patients with acromioclavicular joint disruptions associated with a coracoid base fracture.