Percutaneous Dorsal Approach for Fractures of the Hook of the Hamate: A Less Common but Effective Option

Introduction Hook of hamate fractures are rare. The best treatment option is a source of debate; it ranges from conservative to surgical techniques, including resection of the hook or a volar approach followed by internal fixation. These techniques are not exempt from risk. Minimal invasive fixation using a dorsal percutaneous approach and a headless, cannulated mini screw is another option, although not commonly considered. We present a case series of patients who underwent this surgical technique. Methods This is a retrospective review of four patients with nondisplaced hook of hamate fractures treated with dorsal percutaneous fixation. The evaluation included symptoms, physical examination, and radiological (radiographs, magnetic resonance imaging [MRI], and computed tomography [CT]) findings, as well as pre and postoperative strength (determined with a Jamar (JLW Instruments, Chicago, USA) hydraulic dynamometer) and quick disabilities of the arm, shoulder and hand (QuickDASH) scores. Results The union rate was 100% with no associated complications. All patients resumed their preinjury activities 3 months after the surgery and reported they would undergo surgery again if needed. Conclusion This retrospective study shows that safe treatment of nondisplaced hook of hamate fractures with percutaneous dorsal fixation is feasible, with excellent clinical outcomes. In any case, our sample is limited, and further studies are required.

Biomechanical Analysis of Atlantoaxial Dorsal Fixation Using Finite Element Models

Background: Atlantoaxial instability can cause spinal cord compression with clinical signs ranging from cervical pain to tetraplegia and death. Although a variety of dorsal fixation techniques have been described, some of them have been related to the fracture of the dorsal arch of the atlas, leading to surgical failure. We hypothesized that the shape of the dorsal arch of the atlas and types of implants might affect these bone fractures. Thus, the objective of this study was to analyze bone stresses through simulations of the dorsal fixation using finite element models.Results: The width between wires and the length of the bone did not affect the maximum stress on the bone. The maximum bone stress increased as the bone got thinner and the angle of the notch got steeper. The bone with band implant had lower maximum bone stress than that with wire implants. When using wire implants, wires applied beyond the notch of the dorsal arch reduced the maximum bone stress more than wires positioned within it.Conclusions: The fracture of the dorsal arch of the atlas was related to the shape of the bone and types of implant applied. Band implant can effectively reduce the fracture of the dorsal arch compared to wire implant in atlantoaxial dorsal fixation. When considering wire implant, it is recommended to apply wires beyond the notch of the atlas.

Biomechanical Comparison of Plantar-To-Dorsal and Dorsal-To-Plantar Screw Fixation Strength for Subtalar Arthrodesis

Category: Basic Sciences/Biologics, Hindfoot Introduction/Purpose: Arthrodesis of the subtalar joint is performed for various arthritic and instability problems to correct alignment and relieve pain. For talocalcaneal pathologies, isolated subtalar arthrodesis has been advocated with the advantages of lower risk of adjacent joint arthritis and nonunion of the transverse tarsal joint. Internal fixation techniques have varied over time and use of compression screws is common. The screws may be oriented from dorsal to plantar or plantar to dorsal. Arguments favoring one approach over another are based more on “expert opinion” than hard data. The goal of this study was to compare the biomechanical stability of these two constructs to evaluate which creates a more stable construct. Methods: Eight matched pairs of cadaver feet underwent subtalar joint arthrodesis with two 7.3-mm cannulated screws. Randomization was used to assign screw orientation, such that one foot in each pair was assigned dorsal to plantar screw orientation (DP group), and the other foot plantar to dorsal orientation (PD group). Standard surgical technique with fluoroscopy was used for each approach. Following fixation, each specimen was loaded to failure with a Bionix 858 MTS device, applying a downward axial force at a distance to create torque. Torque to failure was compared between DP and PD groups using Student’s T-test, with p = 0.05 used to determine statistical significance. Results: The force to failure was 585.9 ± 201.1 N for the plantar-to-dorsal fixation and 667.2 ± 449.4 N for the dorsal-to-plantar fixation. The moment arm was 55.1 ± 4.7 mm for the dorsal-to-plantar fixation and 54.8 ± 3.9 mm for the plantar-to-dorsal fixation. Statistical analysis demonstrated that the mean torque to failure slightly favored the DP group (37.3 N-m) to the PD group (32.2 N-m). However, the difference between the two groups was not statistically significant (p = 0.55). Conclusion: There is no significant difference in strength between subtalar arthrodesis performed with dorsal-to-plantar screw orientation and plantar-to-dorsal screw orientation. This suggests that selection of technique should depend on the situation and the required advantages of each. Placing the screw from the heel up has the benefit of being an easier approach, allows access to tenser talar bone once the screw is through, and has less risk of neurovascular injury. The dorsal-to-plantar technique allows simple supine positioning of the patient, needs only two fluoroscopic views to check pin position, and allows the surgeon to manipulate the foot more easily.

Bony Fixation of the Nasal Framework

The importance of a straight and stable central framework is beyond dispute. Many authors allude to technical aspects how to achieve the above-mentioned requirements. Far less is said about the contact zones of the framework and how to achieve a long-lasting and solid fixation. In the authors' patient group, they found the need to work on the septum/the central framework in approximately 84% of the cases. In 61% of the patients, the authors had to operate on the fixation point. Of course, there is a great variety of anatomical findings. So the required techniques differ immensely. The surgeon must be prepared for all kinds of different situations. Especially the dorsal fixation and the anchoring on the maxilla without having a standard anterior nasal spine can be a great challenge. In their daily routine, suture techniques (e.g., the transcutaneous transosseous cerclage suture) have become the authors' working horse for these complex fixation situations.

Comparative Experimental Study of Custom Made Plate for Anterior Stabilization and Dorsal Fixation Systems at C1-C2 Vertebrae Level

Experimental study on the evaluation of strength of fixation with metal constructions at the level of C1-C2 vertebrae was performed on the basis of test laboratory for orthopaedic and traumatologic products. Experiments were performed on the cadaver block preparation (4) and plastic models (8) of craniovertebral spine. Authors’ custom made plate, hook system, screw systems by Magerl and Harms were used as fixators. First step was the imitation of the turning of the head to the right (“twisting”), second step - imitation of head tilting forward (“three point pressure”). It was shown that by its strength and stability of craniovertebral segment the elaborated metal plate was not inferior to dorsal fixation systems.

Comparative Experimental Study of Custom Made Plate for Anterior Stabilization and Dorsal Fixation Systems at C1-C2 Vertebrae Level

Experimental study on the evaluation of strength of fixation with metal constructions at the level of C1-C2 vertebrae was performed on the basis of test laboratory for orthopaedic and traumatologic products. Experiments were performed on the cadaver block preparation (4) and plastic models (8) of craniovertebral spine. Authors’ custom made plate, hook system, screw systems by Magerl and Harms were used as fixators. First step was the imitation of the turning of the head to the right (“twisting”), second step - imitation of head tilting forward (“three point pressure”). It was shown that by its strength and stability of craniovertebral segment the elaborated metal plate was not inferior to dorsal fixation systems.

Surgical Treatment of Scoliosis during the Period of Uncompleted Spine Growth

Outcomes of surgical treatment of 34 patients aged from 9 to 15 years (mean age 11.7 years) with basic curvature arch from 43 to 148° (99° average). In 9 patients dorsal correction and spine fixation by CD system without intervention on the vertebral bodies was performed (1st group). In 25 patients diskepiphysectomy (including thoracoscopic one in 7 patients) and interbody spondylodesis on the apex of the convex basic arch were performed prior to dorsal correction. Then halo-pelvic traction was performed for 7-10 days followed by dorsal fixation of the spine by CDI without posterior spondylodesis (2nd group). Subsequently depending on the degree of correction loss due to spine growth step-by-step corrections of the deformity were performed. After spine growth completion final instrumental correction and fixation of the spine with posterior spondylodesis were performed. In the 1st group step-by-step corrections were to be performed in 77% of cases, in 2nd group - in 28% only. It was shown that performance of diskepiphysectomy on the apex of the deformity with following correction and CD system fixation of the spine decreased the rate of postoperative spine deformity progression, eliminated asymmetric growth of vertebrae on the deformity and increased the achieved correction. In the process of patients' growth wedge shape of the vertebral bodies decreased in frontal and sagittal planes and no increase of their torsion-rotation changes occurred.

Intraosseous ultrasonography to determine the accuracy of drill hole positioning prior to the placement of pedicle screws: an experimental study

Object Dorsal fixation with rods and pedicle screws (PSs) is the most frequently used surgery to correct traumatic and degenerative instabilities of the human spine. Prior to screw placement, screw holes are drilled along the vertebral pedicles. Despite the use of a variety of techniques, misplacement of screw holes, and consequently of the PSs, is a common problem. The authors investigated the usefulness of an intraspinal, intraosseous ultrasonography technique to determine the accuracy of drill hole positioning. Methods An endovascular ultrasound transducer was used for the intraluminal scanning of bore holes in trabecular bovine bone, 12 pedicle drill holes in cadaveric human spine, and 4 pedicle drill holes in a patient undergoing thoracic spondylodesis. Seven of the experimental bore holes in the cadaveric spine were placed optimally (that is, inside the pedicle) and 5 were placed suboptimally (breaching the medial or lateral cortical surface of the pedicle). Computed tomography scans were obtained in the patient and cadaveric specimen after the procedure. Results The image quality achieved in examinations of native bovine bone tissue, the formalin-fixed human spine specimen, and human vertebrae in vivo was equal. The authors endosonographically identified correct intrapedicular and intravertebral positions as well as poor (cortex breached) placement of drill holes. Conclusions Intraosseous ultrasonography is a promising technique for the investigation of PS holes prior to screw implantation, and may add to the safety of PS placement.