Biomechanical comparison of pullout strengths of six pedicle screws with different thread designs

Objectives: This study aims to assess the pullout strength of six different pedicle screw thread patterns

The evaluation of a de novo biplanar distal humerus plate: A biomechanical study

Objectives: The aim of this study was to compare the stability of a novel biplanar distal humerus plate with the single-and double -columns J-plating techniques. Materials and methods: Eighteen sawbones humera were divided into three groups. In Groups 1, 2 and 3, biplanar plate, single lateral J-plate and double J-plate, were used, respectively. Transverse osteotomies at the upper portion of the olecranon fossa were made. Blocks of 10-mm was removed from each sample. Axial, torsional, and extensional stiffness of each group were measured. Results: The mean axial stiffness values in Groups 1, 2, and 3 were 64.80 +/- 6.75, 33.70 +/- 5.71, and 171.48 +/- 9.53 N/mm, respectively. Group 1 demonstrated a statistically significant difference compared to Group 2 (p=0.032), whereas Group 3 showed a statistically significant difference compared to Groups 1 and 2 (p=0.025 and p=0.014, respectively). The mean torsional stiffness values of Groups 1, 2, and 3 were 0.23 +/- 0.01, 0.14 +/- 0.008, and 0.30 +/- 0.007 N/ degree, respectively. Groups 1 and 3 demonstrated a statistically significant difference compared to Group 2 (p=0.042 and p=0.028, respectively). No statistically significant difference was detected between Groups 1 and 3 (p=0.27). The mean extensional bending stiffness values of Groups 1, 2 and 3 were 2.64 +/- 0.31, 1.17 +/- 0.13, and 3.2 +/- 0.1 N/mm, respectively. Group 1 demonstrated a statistically significant difference compared to Group 2 (p=0.041). There was no statistically significant difference between Groups 1 and 3 (p=0.083). Conclusion: Biplanar plate allows applying enough numbers of long sagittal screws and offers more biomechanical stability than lateral column J-plate and in some aspects strong as dual J-plating in torsional and bending tests

Three-Dimensionally-Printed Joint-Preserving Prosthetic Reconstruction of Massive Bone Defects After Malignant Tumor Resection of the Proximal Tibia

Joint-preserving prosthetic reconstruction for massive bone defects has the potential to be a new and revolutionary treatment option. In this paper, we discuss the case of a 30-year-old female patient who presented with pain and swelling around the knee for three months. The patient underwent this procedure. Postoperative patient satisfaction, pain scores, and range of motion results were found to be promising. We believe that this method has the potential to be the next stage in the quest for better treatment options for this condition

A Review of Current Developments in Three-Dimensional Scaffolds for Medical Applications

Humans require treatment due to the loss of tissues after trauma and diseases. Tissue engineering is a growing field of engineering and medical science to restore, maintain, or improve function of damaged or diseased tissues. The use of three-dimension (3D) scaffolds in particular offers a potential option for patients with tissue deficiency. Polylactic acid (PLA), poly-caprolactone (PCL), polyether-ether-ketone (PEEK), and thermoplastic polyurethane (TPU) are biomaterials that are commonly used in tissue engineering. Their applications of pure material or composite and supportive materials are of great importance for clinical practices. This review provides information on biomaterials and major areas of application and discusses their advantages and disadvantages against each other. The literature search from the database PubMed was done for the key words 3D PLA, PCL, PEEK, and TPU separately and 2029 articles were identified. These articles were limited according to clinical, in vivo and observational studies published in English and 140 articles were evaluated for this review. We selected the main articles according to the current data of 3D scaffolds and identical articles were removed. Fifty articles were included in the review. Many studies have reported the advantages of 3D scaffolds with composite or supplement materials over pure materials in the medical treatment. The advances in the development of new 3D scaffolds hold great promise for the prospective applications in the medical treatment

Anatomic implications of lesser trochanterplasty

Objective: The aim of this study was to measure the area of iliopsoas tendon attachment and the distance of sciatic nerve, medial circumflex femoral artery (MCFA) and quadratus muscle to lesser trochanter tip, before and after 5, 10, 15 mm depth excision of lesser trochanter

Comparison of antegrade and retrograde cross pin fixation in the surgical treatment of pediatric supracondylar femur fractures: A biomechanical study

Purpose: The aim of this study is to compare biomechanical stability of Kirschner wires (K-wires) sent with antegrade and retrograde technique in the fixation of pediatric supracondylar femur fractures. Materials and Methods: A transverse fracture model was created two centimeters above the physis in 24 synthetic bone models suitable for the pediatric femur bone structure. The models were randomly divided into two groups as 12 bones each. In the first group (Group 1), 12 bone fracture models were retrogradely fixed with two cross K-wires. In the second group (Group 2), the fracture was fixed antegradely. In Group 2, both wire ends were allowed to protrude three millimeters from the femoral condyles. The stability of the groups was tested biomechanically by exposing them to varus and extension forces. The forces corresponding to 1 mm, 2 mm, 3 mm and 4 mm displacement and failure loads were calculated in two groups. Results: According to the test results regarding displacements and failure loads, the retrograde group was found to be significantly stronger than the antegrade group against varus loads (p 0.05). Conclusion: Retrograde cross K-wires fixation provides a more stable fixation against varus forces. This is important to prevent varus deformity, which is a clinically less tolerable deformity. However, considering that full-weight mobilization of patients is not allowed after surgery in pediatric supracondylar femur fractures, the surgeon should consider that K-wires can also be sent antegrade to decrease the risk of septic arthritis

Bare area on the trochanter and its correlations to gluteal tendon insertion dimensions

Gluteus medius and minimus tears have recently been reported to be very common and the main etiology of lateral sided hip pain. The purpose of this study was to determine whether there is any correlation between the dimensions of the tendon insertions and bare areas (BA) and various bony landmarks. Twenty-seven hemipelvises from adult male hips were included. The bony landmarks [anterior tip (Ta), posterior tip of trochanter, vastus tubercle (VT) and center of BA] were marked. The longitudinal lengths and widths (maximum) of posterosuperior (PS), lateral facets (LF), minimus insertion (Min) and BA and the distance between posterior (Tp) and Ta and between anterior/posterior tips and the VT or center of BA were measured using a digital caliper. A correlation analysis was performed between variables. There was a correlation between LFlength and Min(length) (r = 0.4, P = 0.01) and between Ta-BA and PS + LF (r = 0.5, P = 0.003) or Min(length) (r = 0.4, P = 0.016). LFwidth was negatively correlated with BA(width) (r = -0.4, P = 0.002). Tp-BA was negatively correlated with BA(width) (r = -0.4, P = 0.01). LFwidth was correlated with Tp-BA, and this nearly reached statistical significance (r = 0.3, P = 0.05). BA can be used intraoperatively as landmarks to estimate the width of the LF and also to determine the length of the longitudinal insertion of the gluteus medius and minimus tendons

Comparison of dural closure alternatives: an experimental study

Introduction: Dural closure preference has been a topic of debate in contemporary neurosurgery. This study aims to compare different closure techniques using an in vitro model. Methods: Human cadaveric dura mater was attached to a cylindrical metal glass filled with blue dyed saline. A 1 cm dural incision was made. Dural closure was performed using three different techniques. Each group had six samples: Group I - interrupted simple 4-0 polyglactin suture (S) only, Group II - S plus on lay collagen graft, Group III - S plus fibrin sealant. In Group NS, a 1 cm x 1 cm dural window was made. An onlay collagen graft was used with no suturing for this group to serve as an overtly weak reconstruction reference. Primary and secondary leak pressures were recorded (PLP and SLP, respectively). Results: All groups (I-III) had significantly higher PLP and SLP than Group NS. PLP was significantly higher in Group III as compared to groups I and II. Groups I and II had similar PLP values. SLP was similar in all three groups. Conclusion: In this study, the use of fibrin sealant has proven to be the best option in preventing dural leak. However, no technique was superior in the case of SLP

Suture Anchor Fixation in Osteoporotic Bone: A Biomechanical Study in an Ovine Model

Purpose: To evaluate the load to failure strength of anchor techniques suitable for osteoporotic bone. Methods: Using an osteoporotic ovine model in 72 humeri, 6 fixation techniques were tested. Group 1: two interlocking 5-mm anchors with fewer, wider threads; group 2: one 5-mm anchor; group 3: one 5-mm anchor reinforced laterally by a 6.5-mm cancellous screw; group 4: one 5-mm anchor in an area reinforced with a cancellous plug; group 5: two interlocking 5-mm anchors with smaller threads; group 6: one 5-mm smaller threaded anchor. After a 10-N preload, the specimens were cyclically loaded between 10 N and 30 N for 50 cycles and then destructively tested. Peak-to-peak displacement, cyclic elongation, ultimate load, stiffness, and failure mode were recorded. Results: Group 1 had lower peak-to-peak displacement than group 3 (P =.001), group 5 (P =.001), and group 6 (P =.033). In addition, group 1 showed lower cyclic elongation than group 3 (P =.001), group 5 (P =.035), and group 6 (P =.001). Group 1 had a higher ultimate load than group 2 (P =.002), group 3 (P =.019), and group 6 (P =.006). Group 1 also showed higher stiffness than group 2 (P =.007) and group 3 (P =.022). Mode of failure was predominantly caused by anchor pullout for all of the groups except group 3, which mainly failed by suture rupture. Conclusions: Two interlocking suture anchors are stronger than a single anchor in osteoporotic bone. The anchor with fewer, wider threads and a smaller core diameter showed greater strength and less elongation than the other constructs. Reinforcement by cancellous autografting increased suture anchor strength