Ipsilateral Neck/Inter-Trochanteric and Mid-shaft Femoral Fractures Treated with Dual Construct Implants

Background: Various management protocols for ipsilateral neck/intertrochanteric and shaft fracture femur have been formulated, there have been many disagreements related to their ideal fixation plan. The aim of this study was to discuss the various type of fixation system available for such kind of complex injuries and the advantages of using dual construct fixation system. Patient and Methods: In the present study we prospectively evaluated ipsilateral neck/intertrochanteric and shaft fracture femur in 7 cases managed from January 2018 to December 2020. All the patients were managed with dual constructs fixation system using dynamic hip screw (DHS) and locking plate. The outcome was evaluated using Friedman and Wyman scoring system. Results: The average surgical time was 120.4 min (range 98–143 minutes) with a blood loss ranging from 290-565 mL (average 460 mL). In 6 patients follow-up was undertaken between 10 and 22-months after surgery, with a mean follow-up time of 16.2 months. 1 patient lost follow-up at 3-month. The neck/IT fractures achieved union in 6 patients at the final follow-up. 3-6 months was the duration for bone union, with an average of 4.1 months. The mid-shaft femur fractures achieved solid union in 6 cases at the most recent follow-up. 3 to 11 months was the duration of union, with a mean of 5.1 months. 1 patient went into non-union 11 months after the surgery. According to Friedman and Wyman scoring, 4 patients the functional outcome was good, in 2 patients the functional outcome was fair, and in 1 patient the functional outcome at the final follow-up was poor. The problems noted were surgical site infection in 1, Angulations (varus/valgus) of femoral neck in 1, non-union of neck femur fracture in 1, and avascular necrosis of femoral head in 1. Conclusion: The management of ipsilateral neck/intertrochanteric and shaft fracture femur with dual construct implants dynamic hip screw for neck/IT fracture and locking plate for shaft femoral fractures yielded good union rates and good functional outcomes.

Histometric and Histological Analysis of Bone to Screw Contact Between Metallic and Absorbable 2.0 Fixation System: A Pilot Study in Dogs

ObjectiveTo evaluate the bone/screw interface of a titanium IF system and an absorbable IF system.Materials and methodsTwelve male adult dogs were subjected to osteotomy performed between the third and fourth mandibular premolars, been divided into two groups (control or experimental side). Two miniplates were applied to fix mandible fragments. Histometric values for bone-to-screw contact (BSC), bone-to-screw distance (BSD) and histological findings were evaluated at 2 and 18 weeks.ResultsDifference in BSC were detected from absorbable and metallic monocortical group on the experimental side at 2 weeks (p = 0.0041). Larger BSDs were detected at buccal bicortical absorbable experimental sides (p = 0.0041), with larger distances detected from the vestibular side to the lingual cortical side (p < 0.0001) and on the control side at 18 weeks (p = 0.0143), having metallic group significant BSD results on the experimental side at 2 weeks (p = 0.047). Connective tissue was noted on vestibular cortical side in monocortical and bicortical absorbable screw groups. ConclusionsAbsorbable bicortical screws with splint had histometric and histological behaviors similar to metallic bicortical group at lingual cortical side.Clinical RelevanceInion absorbable bicortical screws did not promote connective tissue formation at lingual cortical side.

Case Report: Spinal Stabilization Surgery Using a Novel Custom-Made Titanium Fixation System for the Spinal Instability Caused by Vertebral Malformation in a Dog

A 2-year-old Maltese was presented with wobbly gait of the pelvic limbs. Based on imaging examinations, a diagnosis of congenital malformation at T5–T8 and severe kyphosis causing spinal cord compression at T6–T7 was made. Dorsal laminectomy and stabilization of T6 and T7 vertebrae were performed. As the size of the vertebrae was small and they were severely deformed, novel custom-made titanium implants were used for spinal stabilization. Clinical signs were resolved 2 weeks after surgery. Although radiographic examination 373 days after surgery showed slight loosening of implants, post-operative course remained uneventful. This report describes the use of novel custom-made titanium implants for spinal fixation surgery in a dog.

Finite Element Analysis and Comparative Study of 4 Kinds of Internal Fixation Systems for Anterior Cervical Discectomy and Fusion in Children

Background: Spinal injury in children usually occurs in the cervical spine region. Anterior fixation of lower cervical spine has been applied in the treatment of pediatric cervical spine injury and disease due to its stable and firm mechanical properties. This study performed finite element analysis and comparison of 4 different anterior cervical internal fixation systems for children, and explored more stable methods of anterior cervical internal fixation in children. Methods: A finite element model of 6-year-old children with lower cervical spine C4/5 discectomy was established, and the self-designed lower cervical spine anterior locking internal fixation system ACBLP and the children’s anterior cervical internal fixation system ACOP, ACVLP, ACSLP plate screws were fixed and loaded on the model. 27.42N•m torque load was applied to each internal fixation model under 6 working conditions of anteflexion, backward flexion, left flexion, right flexion, left rotation and right rotation, to simulate the movement of the cervical spine. The activity and stress distribution cloud diagram of each finite element model was obtained. Results: In the four internal fixation models of ACOP, ACVLP, ACSLP, and ACBLP, the mobility of C4/5 segment basically showed a decreasing relationship, and the mobility of adjacent segments increased significantly. In the Mises stress cloud diagram of the cervical spine of the four models, the vertebral body and accessories of the ACBLP model born the least stress, followed by ACSLP; The steel plate and screws in the ACVLP internal fixation model were the most stressed; The stress of the internal fixation system (plate/screw) in all models increased in the order of ACBLP, ACSLP, ACVLP, and ACOP.Conclusions: ACBLP internal fixation system had obvious advantages in anterior internal fixation of lower cervical spine in children, C4/5 had the smallest degree of movement, relative displacement was minimal, the stress on the pedicle was the least while the stress on the plate screw was relatively the smallest.

A Finite Element Analysis of the Effects of Different Internal Fixation Strategies and Cage Implantation Methods on the Biomechanics of the Lumbar Spine

Objective: Providing the biomechanical evidences to the surgeons on the internal fixation strategy and Cage implantation method in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) by the finite element analysis (FEA).Methods: Firstly, based on the common MIS-TLIF surgical methods, three surgical models with different internal fixation strategies and Cage implantation methods were established. The surgical models simulated the physiological activities of the lumbar spine to evaluate the range of motion (ROM) of lumbar spine, the peak stress and the overall stress of the internal fixation system and Cage.Results: The results of the study show that the ROM of the surgical model has decreased significantly under all working conditions, and the decrease range is between 71.07-97.53%. The peak stress of the internal fixation system range was 48.56 to 100.09 MPa in Model-A, 58.10 to 136.05 MPa in Model-B, and 83.26 to 189.81 MPa in Model-C. Especially in the three working conditions of left lateral bending (LLB), left rotation (LR), and right rotation (RR), the peak stress of the internal fixation system of Model-C is 1.80 , 2.07, 1.79 times of Model-A and 2.05 , 1.64, 2.28 times of Model-B. The peak stress of Model-C Cage is significantly lower than Model-A and Model-B under all working conditions.Conclusion: Although the strategy of unilateral pedicle screw + lamina articular process screw + Cage horizontal implantation has the least Cage stress, there is a higher risk of internal fixation fail. Comprehensive evaluation, the surgical strategy of bilateral pedicle screw + Cage horizontal implantation has the best performance, and has the potential to become the standard implantation strategy of MIS-TLIF.

Strength of interference screw fixation of meniscus prosthesis matches native meniscus attachments

Purpose Meniscal surgery is one of the most common orthopaedic surgical interventions. Total meniscus replacements have been proposed as a solution for patients with irreparable meniscal injuries. Reliable fixation is crucial for the success and functionality of such implants. The aim of this study was to characterise an interference screw fixation system developed for a novel fibre-matrix-reinforced synthetic total meniscus replacement in an ovine cadaveric model. Methods Textile straps were tested in tension to failure (n = 15) and in cyclic tension (70–220 N) for 1000 cycles (n = 5). The textile strap-interference screw fixation system was tested in 4.5 mm-diameter single anterior and double posterior tunnels in North of England Mule ovine tibias aged > 2 years using titanium alloy (Ti6Al4Va) and polyether-ether-ketone (PEEK) screws (n ≥ 5). Straps were preconditioned, dynamically loaded for 1000 cycles in tension (70–220 N), the fixation slippage under cyclic loading was measured, and then pulled to failure. Results Strap stiffness was at least 12 times that recorded for human meniscal roots. Strap creep strain at the maximum load (220 N) was 0.005 following 1000 cycles. For all tunnels, pull-out failure resulted from textile strap slippage or bone fracture rather than strap rupture, which demonstrated that the textile strap was comparatively stronger than the interference screw fixation system. Pull-out load (anterior 544 ± 119 N; posterior 889 ± 157 N) was comparable to human meniscal root strength. Fixation slippage was within the acceptable range for anterior cruciate ligament graft reconstruction (anterior 1.9 ± 0.7 mm; posterior 1.9 ± 0.5 mm). Conclusion These findings show that the textile attachment-interference screw fixation system provides reliable fixation for a novel ovine meniscus implant, supporting progression to in vivo testing. This research provides a baseline for future development of novel human meniscus replacements, in relation to attachment design and fixation methods. The data suggest that surgical techniques familiar from ligament reconstruction may be used for the fixation of clinical meniscal prostheses.