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Biomechanics external fixator

Augusta Whitney Kluk, Tina Zhang, Joseph P Russell, Hyunchul Kim, Adam H Hsieh, Robert V O'Toole
Orthopedic dogma states that external fixator stiffness is improved by placing 1 pin close to the fracture and 1 as distant as possible ("near-far"). This fixator construct is thought to be less expensive than placing pins a shorter distance apart and using "pin-bar" clamps that attach pins to outriggers. The authors therefore hypothesized that the near-far construct is stiffer and less expensive. They compared mechanical stiffness and costs of near-far and pin-bar constructs commonly used for temporary external fixation of femoral shaft fractures...
October 13, 2016: Orthopedics
Thomas O Clanton, Brady T Williams, Jonathon D Backus, Grant J Dornan, Daniel J Liechti, Scott R Whitlow, Adriana J Saroki, Travis Lee Turnbull, Robert F LaPrade
BACKGROUND: Biomechanical data and contributions to ankle joint stability have been previously reported for the individual distal tibiofibular ligaments. These results have not yet been validated based on recent anatomic descriptions or using current biomechanical testing devices. METHODS: Eight matched-pair, lower leg specimens were tested using a dynamic, biaxial testing machine. The proximal tibiofibular joint and the medial and lateral ankle ligaments were left intact...
September 28, 2016: Foot & Ankle International
Thomas O Clanton, Scott R Whitlow, Brady T Williams, Daniel J Liechti, Jonathon D Backus, Grant J Dornan, Adriana J Saroki, Travis Lee Turnbull, Robert F LaPrade
BACKGROUND: Significant debate exists regarding optimal repair for unstable syndesmosis injuries. Techniques range from screw fixation, suture-button fixation, or a combination of the two. In this study, 3 common repairs were compared using a simulated weightbearing protocol with internal and external rotation of the foot. METHODS: Twenty-four lower leg specimens with mean age 54 years (range, 38-68 years) were used for testing. Following creation of a complete syndesmotic injury (AITFL, ITFL, PITFL, interosseous membrane), specimens were repaired using 1 of 3 randomly assigned techniques: (1) one 3...
September 25, 2016: Foot & Ankle International
Breck R Lord, Hadi El-Daou, Bhushan M Sabnis, Chinmay M Gupte, Adrian M Wilson, Andrew A Amis
PURPOSE: Double-bundle (DB) anterior cruciate ligament (ACL) reconstruction may offer kinematic restoration superior to anatomic single bundle (SB), but it remains technically challenging. The femoral attachment site has the most effect on ACL graft isometry, so a simplified three-socket (3S) construct which still uses two sockets to cover the femoral ACL attachment is attractive. It was hypothesised that ACL reconstruction using three- and four-socket techniques would more closely restore native knee kinematics compared to anatomic two-socket (SB) surgery...
September 16, 2016: Knee Surgery, Sports Traumatology, Arthroscopy: Official Journal of the ESSKA
Paul J Switaj, Daniel Fuchs, Mohammed Alshouli, Avinash G Patwardhan, Leonard I Voronov, Muturi Muriuki, Robert M Havey, Anish R Kadakia
BACKGROUND: A lateral approach with open reduction and internal fixation with a plate is a very effective technique for the majority of distal fibular fractures. However, this open approach for ankle fixation may be complicated by wound dehiscence and infection, especially in high-risk patients. An alternative to plating is an intramedullary implant, which allows maintenance of length, alignment, and rotation and which allows for decreased soft tissue dissection. While there has been clinical data suggesting favorable short-term outcomes with these implants, there is no current biomechanical literature investigating this technology in this particular fracture pattern...
2016: Journal of Orthopaedic Surgery and Research
Justin Brantley, Aditi Majumdar, J Taylor Jobe, Antony Kallur, Christina Salas
BACKGROUND: Percutaneous pin fixation is often used in conjunction with closed-reduction and cast immobilization to treat pediatric distal tibia fractures. The goal of this procedure is to maintain reduction and provide improved stabilization, in effort to facilitate a more anatomic union. We conducted a biomechanical study of the torsional and bending stability of three commonly used pin configurations in distal tibia fracture fixation. METHODS: A transverse fracture was simulated at the metaphyseal/diaphyseal junction in 15 synthetic tibias...
2016: Iowa Orthopaedic Journal
Wei Ye, Nirong Bao, Jianning Zhaq
OBJECTIVE: To compare the difference of rotator cuff healing between different types of injury andbetween different repair methods, and to explore the animal model to accurately simulate the restorative process afterrepair of rotator cuff injury. METHODS: Twelve adult male beagle dogs (weighing, 10-15 kg) were divided into 3 groups (n = 4) according to different processing methods: acute rotator cuff injury+Mason-Allen suture repair (group A), huge rotator cuff injury+Mason-Allen suture repair (group B), and huge rotator cuff injury+Mason-Allen combined with autogenous semitendinosus expansion suture repair (group C)...
April 2016: Chinese Journal of Reparative and Reconstructive Surgery
Joseph L Petfield, Garry T Hayeck, David L Kopperdahl, Leon J Nesti, Tony M Keaveny, Joseph R Hsu
Virtual stress testing provides a non-invasive estimate of the strength of a healing bone through a biomechanical analysis of a patient's computed tomography (CT) scan. We asked whether virtual stress testing could improve management of patients who had a tibia fracture treated with external fixation. In a retrospective case-control study of 65 soldier-patients who had tibia fractures treated with an external fixator, we performed virtual stress testing utilizing CT scans acquired prior to fixator removal. The strength of the healing bone and the amount of tissue damage after application of an overload were computed for various virtual loading cases...
June 15, 2016: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
M D Fletcher
INTRODUCTION: Correction of limb alignment or length discrepancy by circular external fixation is an accepted technique which relies on the correct biomechanical application of the frame and precise corrections which are frequently delegated to the patient to perform. Errors can occur in the execution of the correction by the patient and may result in significant deformity that requires remedial intervention. CASE REPORT: A 67 Caucasian female underwent multifocal limb reconstruction of the lower limb utilising a complex Ilizarov frame...
July 2015: Journal of Orthopaedic Case Reports
Jagannath B Kamath, Nikil Jayasheelan, Amaranth Savur, Rejith Mathews
BACKGROUND: Unstable fractures of the metacarpal and phalangeal bones of the hand need surgical stabilization which should be rigid enough for early active mobilization. Conventional methods of open reduction and stabilization in the form of composite fixation or screws with or without plates have served the purpose but can be definitely improvised addressing both biological and mechanical principles of fixation. MATERIALS AND METHODS: 34 patients (29 males and 5 females) with an average age of 32 years (range 10-64 years) with unstable fractures of the metacarpal and phalangeal bones of hand who were treated with the modified bone tie between June 2009 and June 2013 were included in this study...
May 2016: Indian Journal of Orthopaedics
Lucas S McDonald, Matthew Thompson, David W Altchek, Michelle H McGarry, Thay Q Lee, Vanna J Rocchi, Joshua S Dines
PURPOSE: Using a cadaver shoulder instability model and load-testing device, we compared biomechanical characteristics of double-row and single-row capsulolabral repairs. We hypothesized a greater reduction in glenohumeral motion and translation and a higher load to failure in a mattress double-row capsulolabral repair than in a single-row repair. METHODS: In 6 matched pairs of cadaveric shoulders, a capsulolabral injury was created. One shoulder was repaired with a single-row technique, and the other with a double-row mattress technique...
May 18, 2016: Arthroscopy: the Journal of Arthroscopic & related Surgery
Taku Hatta, Hugo Giambini, Koji Sukegawa, Yoshiaki Yamanaka, John W Sperling, Scott P Steinmann, Eiji Itoi, Kai-Nan An
The deltoid muscle plays a critical role in the biomechanics of shoulders undergoing reverse shoulder arthroplasty (RSA). However, both pre- and postoperative assessment of the deltoid muscle quality still remains challenging. The purposes of this study were to establish a novel methodology of shear wave elastography (SWE) to quantify the mechanical properties of the deltoid muscle, and to investigate the reliability of this technique using cadaveric shoulders for the purpose of RSA. Eight fresh-frozen cadaveric shoulders were obtained...
2016: PloS One
Yu Zhan, Xiaoyu Yan, Ronggang Xia, Tao Cheng, Congfeng Luo
PURPOSE: Syndesmosis injury is common in external-rotation type ankle fractures (ERAF). Trans-syndesmosis screw fixation, the gold-standard treatment, is currently controversial for its complications and biomechanical disadvantages. The purpose of this study was to introduce a new method of anatomically repairing the anterior-inferior tibiofibular ligament (AITFL) and augmentation with anchor rope system to treat the syndesmotic instability in ERAF with posterior malleolus involvement and to compare its clinical outcomes with that of trans-syndesmosis screw fixation...
July 2016: Injury
Chenguang Hao, Yanlong Wang, Lin Shao, Jianyu Liu, Lin Chen, Zhenyu Zhao
INTRODUCTION: This study aimed to evaluate the efficacy of local injection of bone mesenchymal stem cells (BMSCs) and fibrin glue in the treatment of atrophic nonunion in an animal model. METHODS: Thirty-six male Lewis rats were randomly assigned into three groups: Group A (control group), Group B (atrophic nonunion group), and Group C (experimental group). All the rats underwent femoral osteotomy of the right hind limb, and stabilized with a custom-designed external fixator...
May 2016: Advances in Therapy
S R Small, R D Rogge, R A Malinzak, E M Reyes, P L Cook, K A Farley, M A Ritter
OBJECTIVES: Initial stability of tibial trays is crucial for long-term success of total knee arthroplasty (TKA) in both primary and revision settings. Rotating platform (RP) designs reduce torque transfer at the tibiofemoral interface. We asked if this reduced torque transfer in RP designs resulted in subsequently reduced micromotion at the cemented fixation interface between the prosthesis component and the adjacent bone. METHODS: Composite tibias were implanted with fixed and RP primary and revision tibial trays and biomechanically tested under up to 2...
April 2016: Bone & Joint Research
Nando Ferreira, Leonard Charles Marais, Colleen Aldous
BACKGROUND: Recent research indicates that atrophic nonunions are biologically active and may heal in the optimal biomechanical environment. METHODS: Thirty-three patients with mobile atrophic and oligotrophic tibial nonunions were treated with circular external fixation and functional rehabilitation. Seven patients required autogenous bone graft procedures. RESULTS: Bony union was achieved after the initial surgery in 31/33 (93.9%) tibias...
December 2015: Journal of Orthopaedics
Ahmad El-Sayed Semaya, Ehab Badawy, Mohammad Hasan, Ramy Mohammad El-Nakeeb
INTRODUCTION: Post-traumatic bone defects of the tibia present a difficult reconstructive challenge. Various methods of reconstruction are available, such as allografts, vascularised fibular graft (either free or pedicled) and bone transport technique. PATIENTS AND METHODS: Fourteen patients with an average age of 34.1 years at operation (range, 12-65) with post-traumatic bony defects of the tibia were selected for reconstruction with vascularised fibular graft combined with Ilizarov external fixation...
April 2016: Injury
Jun Fei, Zhen Lai, Wei Wei, De-xin Hu, Yong-jie Yu
OBJECTIVE: To evaluate biomechanical properties in different methods of internal fixation combined with distal tibiofibular syndesmosis injury, in order to provide a theoretical basis for clinical choice. METHODS: Six lower limbs specimens were collected and divided into 5 groups, including normal group, distal tibiofibular syndesmosis injury (injury group), 3 cortexes group, 4 cortexes group and hook-plate fixation group. Neutral position, plantar flexion position (30°), dorsiflexion (20°) supination external rotation position of foot movement were simulated on universal materials tester...
December 2015: Zhongguo Gu Shang, China Journal of Orthopaedics and Traumatology
Mihir J Desai, William M Reisman, William C Hutton
The purpose of this study was to test and compare external fixator construct stiffness using pin-to-bar clamps or multipin clamps across 2 external fixation systems. Constructs were tested with 8-mm and 11-mm-diameter bar systems and pin-to-bar or multipin clamps. Three construct designs were tested: construct 1 with a single crossbar and pin-to-bar clamps, construct 2 with 2 crossbars and pin-to-bar clamps, and construct 3 with 2 crossbars and multipin clamps. The stiffness of each construct (N = 24) was tested using anterior-posterior bending...
February 2016: American Journal of Orthopedics
Filon Agathangelidis, Georgios Petsatodis, John Kirkos, Pericles Papadopoulos, Dimitrios Karataglis, Anastasios Christodoulou
Recently introduced tibial intramedullary nails allow a number of distal screws to be used to reduce the incidence of malalignment and loss of fixation of distal metaphyseal fractures. However, the number of screws and the type of screw configuration to be used remains obscure. This biomechanical study was performed to address this question. Thirty-six Expert tibial nails (Synthes, Oberdorf, Switzerland) were introduced in composite bone models. The models were divided into 4 groups with different distal locking configurations ranging from 2 to 4 screws...
March 2016: Orthopedics
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