A Novel Construct Incorporating C2 Unilateral Pedicle and Contralateral Translaminar Screws for Occipitocervical Internal Fixation: An In Vitro Biomechanical Study

Abstract Background All current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue. Methods First, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined. Results A model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69). Conclusions All measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument.

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Whether sutures reduce the graft laceration caused by interference screw in anterior cruciate ligament reconstruction? A biomechanical study in vitro

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04457-5 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Yuanjun Teng ◽

Xiaohui Zhang ◽

Lijun Da ◽

Jie Hu ◽

Hong Wang ◽

...

Keyword(s):

Acl Reconstruction ◽

Cruciate Ligament ◽

Interference Screw ◽

Biomechanical Study ◽

Interference Screws ◽

Suture Group ◽

Anterior Cruciate ◽

Biomechanical Tests ◽

Single Insertion

Abstract Background Interference screw is commonly used for graft fixation in anterior cruciate ligament (ACL) reconstruction. However, previous studies had reported that the insertion of interference screws significantly caused graft laceration. The purposes of this study were to (1) quantitatively evaluate the graft laceration from one single insertion of PEEK interference screws; and (2) determine whether different types of sutures reduced the graft laceration after one single insertion of interference screws in ACL reconstruction. Methods The in-vitro ACL reconstruction model was created using porcine tibias and bovine extensor digitorum tendons of bovine hind limbs. The ends of grafts were sutured using three different sutures, including the bioabsorbable, Ethibond and ultra-high molecular weight polyethylene (UHMWPE) sutures. Poly-ether-ether-ketone (PEEK) interference screws were used for tibial fixation. This study was divided into five groups (n = 10 in each group): the non-fixed group, the non-sutured group, the absorbable suture group, the Ethibond suture group and the UHMWPE suture group. Biomechanical tests were performed using the mode of pull-to-failure loading tests at 10 mm/min. Tensile stiffness (newtons per millimeter), energy absorbed to failure (in joules) and ultimate load (newtons) were recorded for analysis. Results All prepared tendons and bone specimens showed similar characteristics (length, weight, and pre-tension of the tendons, tibial bone mineral density) among all groups (P > 0.05). The biomechanical tests demonstrated that PEEK interference screws significantly caused the graft laceration (P < 0.05). However, all sutures (the bioabsorbable, Ethibond and UHMWPE sutures) did not reduce the graft laceration in ACL reconstruction (P > 0.05). Conclusions Our biomechanical study suggested that the ultimate failure load of grafts was reduced of approximately 25 % after one single insertion of a PEEK interference screw in ACL reconstruction. Suturing the ends of the grafts using different sutures (absorbable, Ethibond and UHMWPE sutures) did not decrease the graft laceration caused by interference screws.

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The Effectiveness of a Hinged Elbow Orthosis in Medial Collateral Ligament Injuries: An In Vitro Biomechanical Study

The American Journal of Sports Medicine ◽

10.1177/0363546519870517 ◽

2019 ◽

Vol 47 (12) ◽

pp. 2827-2835

Author(s):

Ranita H.K. Manocha ◽

James A. Johnson ◽

Graham J.W. King

Keyword(s):

Medial Collateral Ligament ◽

Muscle Activation ◽

Mechanical Stability ◽

Biomechanical Study ◽

Return To Play ◽

Collateral Ligament ◽

Valgus Stress ◽

Active Motion ◽

Early Return

Background: Medial collateral ligament (MCL) injuries are common after elbow trauma and in overhead throwing athletes. A hinged elbow orthosis (HEO) is often used to protect the elbow from valgus stress early after injury and during early return to play. However, there is minimal evidence regarding the efficacy of these orthoses in controlling instability and their influence on long-term clinical outcomes. Purpose: (1) To quantify the effect of an HEO on elbow stability after simulated MCL injury. (2) To determine whether arm position, forearm rotation, and muscle activation influence the effectiveness of an HEO. Study Design: Controlled laboratory study. Methods: Seven cadaveric upper extremity specimens were tested in a custom simulator that enabled elbow motion via computer-controlled actuators and motors attached to relevant tendons. Specimens were examined in 2 arm positions (dependent, valgus) and 2 forearm positions (pronation, supination) during passive and simulated active elbow flexion while unbraced and then while braced with an HEO. Testing was performed in intact elbows and repeated after simulated MCL injury. An electromagnetic tracking device measured valgus angulation as an indicator of elbow stability. Results: When the arm was dependent, the HEO increased valgus angle with the forearm in pronation (+1.0°± 0.2°, P = .003) and supination (+1.5°± 0.0°, P = .006) during active motion. It had no significant effect on elbow stability during passive motion. In the valgus position, the HEO had no effect on elbow stability during passive or active motion in pronation and supination. With the arm in the valgus position with the HEO, muscle activation reduced instability during pronation (–10.3°± 2.5°, P = .006) but not supination ( P = .61). Conclusion: In this in vitro study, this HEO did not enhance mechanical stability when the arm was in the valgus and dependent positions after MCL injury. Clinical Relevance: After MCL injury, an HEO likely does not provide mechanical elbow stability during rehabilitative exercises or when the elbow is subjected to valgus stress such as occurs during throwing.

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Osteochondral Lesions of the Capitellum Do Not Affect Elbow Kinematics and Stability With Intact Collateral Ligaments: An In Vitro Biomechanical Study

The Journal Of Hand Surgery ◽

10.1016/j.jhsa.2010.09.037 ◽

2011 ◽

Vol 36 (1) ◽

pp. 74-80 ◽

Cited By ~ 3

Author(s):

Marlis T. Sabo ◽

Colin P. McDonald ◽

Louis M. Ferreira ◽

Jim A. Johnson ◽

Graham J. King

Keyword(s):

Biomechanical Study ◽

Osteochondral Lesions ◽

Collateral Ligaments

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A Biomechanical Evaluation of Three Forms of Internal Fixation Used in Ankle Arthrodesis

Foot & Ankle International ◽

10.1177/107110079401500603 ◽

1994 ◽

Vol 15 (6) ◽

pp. 297-300 ◽

Cited By ~ 45

Author(s):

Michael P. Dohm ◽

James B. Benjamin ◽

Jeffrey Harrison ◽

John A. Szivek

Keyword(s):

Internal Fixation ◽

Plate Fixation ◽

Ankle Arthrodesis ◽

Biomechanical Study ◽

The Other ◽

Fixation Failure ◽

Plate Group ◽

Biomechanical Evaluation ◽

The Stability ◽

Fibular Strut

A biomechanical study was undertaken to evaluate the relative stability of three types of internal fixation used for ankle arthrodesis. Crossed screw fixation, RAF fibular strut fixation, and T-plate fixation were tested in 30 cadaver ankles using an MTS machine. T-plate fixation consistantly provided the stiffest construct when compared with the other types of fixation. Failure occurred by distraction of bony surfaces, posterior to the plane of fixation, in the crossed screw and RAF groups. In contrast, failure in the T-plate group occurred through compression of bone anterior to the midcoronal plane of the tibia. Although the stability of fixation is only one factor in determining the success or failure of ankle arthrodesis, the results of this study would support T-plate fixation over the other forms tested.

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