Transarticular Screw Research Articles

Philosophies And Surgical Techniques on Os Odontoideum Treatment with Literature Review.

Os-odontoideum is a rare condition described radiographically and clinically as a congenital anomaly of the second cervical vertebra (axis). It is a smooth, independent ossicle of variable size and shape separated from the base of a shortened odontoid process by an obvious gap, with no osseous connection to the body of C2. This study reviewed the literature on OO to evaluate its etiology, clinical presentations, differential diagnosis, imaging modalities, and outcomes in the management of asymptomatic and symptomatic cases of Os Odontoideum. Key articles from PubMed, EMBASE, Google Scholar, and Cochrane were searched. Considering etiology, the traumatic hypothesis is favoured over the congenital hypothesis as per recent literature on OO. Clinical presentation varies from asymptomatic to mild neck pain to severe myelopathy and neurodeficit. Various C1-C2 instrumentation and fusion techniques like wiring, trans articular screw and laminar screws have been described with success rates. Os odontoideum is a rare condition with limited existing literature. Considering the significant risks involved if conservative management opts, like severe neuro deficit to sudden death on trivial trauma and the recent improvement of imaging tools helping to understand the pathology of the disease, surgery can be indicated even in an incidentally detected os odontoideum. However, a case-by-case approach can be considered for stable asymptomatic patients depending on factors such as age, activity level, comorbidities, syndromic association, and radiographic findings.

Mechanical Properties and Failure Mode of Proximal Screw Fixation Technique Using Locking Compression Plate for Proximal Interphalangeal Arthrodesis in Horses: An Ex Vivo Study.

The aim of this study was to measure the mechanical properties and failure mode of an ex vivo model of proximal interphalangeal arthrodesis in horses with different methods of proximal screw fixation using a locking compression plate. Pastern joint arthrodesis with a 3-hole 4.5-mm narrow locking compression plate was performed on 20 forelimbs of equine cadavers, randomized into four groups based on the fixation method and type of proximal screw used: unicortical cortex, bicortical cortex, unicortical locking, bicortical locking. Single-cycle axial compression testing was conducted until failure. The frequency of implant plastic deformation was recorded. Bone failure analysis was performed through computed tomography examinations and fractal analysis. There were no differences in the analysed mechanical variables and fractal dimension among the groups. Transarticular screws showed a higher frequency of deformation (75%) regardless of the group. Both unicortical locking and bicortical locking groups deformed the plate more frequently. The type of screw used in the proximal hole of the locking compression plate and its method of anchoring in the proximal phalanx do not affect the mechanical properties of pastern arthrodesis in equine cadavers subjected to single-cycle axial compression tests until failure.

Evaluation of the Bone Union Occurring Subsequent to C1-2 Fusion Combined With C1 Laminectomy for the Surgical Treatment of Retro-Odontoid Pseudotumor.

Introduction Surgical treatments for retro-odontoid pseudotumors (ROPs) include C1 laminectomies and C1-2 and occipitocervical (OC) fusions. When a C1 laminectomy is combined with a C1-2 fusion, concerns arise regarding an increased risk of pseudarthrosis due to decreased bone grafting space. Extension of the fusion area to the OC region may be considered to ensure an adequate bone graft bed. However, this procedure is associated with a risk of complications. Thus, in this study, we investigated the bone fusion and clinical outcomes of C1-2 fusion combined with a C1 laminectomy. Methods Between January 2017 and December 2022, seven patients with ROPs who had undergone C1-2 fusion combined with a C1 laminectomy were included in the study. All patients were followed up for >1 year. Bone fusion was evaluated by computed tomography (CT) at one year postoperatively, while implant failure was assessed by radiography at the final follow-up. Clinical evaluations included preoperative and one-year postoperative Japanese Orthopaedic Association (JOA) scores and recovery rates. Results This study included five male and two female patients, with an average age of 71.9 years. The average follow-up duration was 3.3 years. The primary anchor choices included the C1 lateral mass screw and the C2 pedicle screw. In one case, the transarticular screw was utilized unilaterally, and in another case, a lamina screw was utilized unilaterally. One year postoperatively, CT revealed bone fusion in three of the seven patients. Fusion occurred at the lateral and median atlantoaxial joints in two cases and one case, respectively. Screw loosening was observed in one case. None of the patients required reoperations. The average JOA recovery rate was 34.6%. Conclusion This surgical technique is useful for stabilizing and decompressing the C1-2 region while preserving mobility at the OC joint. However, further long-term follow-up studies are required.

Characteristics of Screw Perforation and Screw Loosening in Atlantoaxial Transarticular Fixation Using a Preoperative Computed Tomography-Based Navigation System.

Atlantoaxial transarticular fixation, also called the Magerl technique, is said to be the most robust biomechanical method of fixation of the atlantoaxial vertebrae. However, the procedure carries a risk of spinal cord and vertebral artery injury during the insertion process, especially in patients with a high-riding vertebral artery. In this study, a computed tomography (CT)-based navigation system was used for preoperative planning and insertion. This investigation sought to determine the rate and direction of screw perforation as well as the incidence of screw loosening in computer-assisted atlantoaxial transarticular fixation. Sixty patients (31 men and 29 women; mean ± SD age: 65.3 ± 19.6 years) who received atlantoaxial transarticular screw insertion with preoperative CT navigation were analyzed. We investigated screw position and loosening by CT at the final follow-up. Of the 108 screws inserted, the rate of Grade 2 or higher perforation was 4.6% (5/108). Nine of 81 (11.1%) screws inserted into the 44 patients who were followed for at least 6 months showed loosening. Logistic regression analysis revealed that unilateral insertion (odds ratio: 8.50, 95% confidence interval: 1.53-47.2, P = 0.014) was significantly associated with the incidence of screw loosening. The screw perforation rate of Grade 2 or higher in computer-assisted atlantoaxial transarticular screw fixation was 4.6%, with comparable frequencies of perforation direction. Unilateral insertion was a significant independent factor associated with screw loosening, which occurred in 11.1% of insertions. Spine surgeons should follow up with patients with caution because screws with unilateral insertion are prone to loosening.

Rare Indication of Atlantoaxial Fusion-failed Conservative Management of Primary Atlantoaxial Osteoarthritis

Introduction: Osteoarthritis of the atlantoaxial joint is a significant cause of occipitocervical pain, which is often missed and has an increasing prevalence with age. The patients typically present with occipitocervical pain and restricted and painful neck rotations. Despite the primary reliance on conservative management for this pathology, surgical intervention becomes crucial for those not responding to standard conservative treatment. The presented case series highlights the rarity of the requirement of surgical intervention in the management of Atlantoaxial osteoarthritis (AAOA) and the clinical outcomes of surgical management in AAOA. Case Report: This paper presents a case series of four patients who were managed surgically with atlantoaxial fusion, from a database of 108 patients with AAOA. The case series includes three males and one female with a mean age of presentation being 67.5 years. All four patients presented with occipitocervical pain, and painful neck movements and were diagnosed with AAOA on the anteroposterior open mouth view radiographs showing changes of osteoarthritis such as bone erosions, sclerosis, osteophytes. The patients were managed conservatively with non-steroidal anti-inflammatory drugs, intra-articular steroid injections, and cervical collar immobilization. Those not responding to conservative management and with incapacitating pain were managed surgically with atlantoaxial fusion procedures. Conclusion: In a group of patients with a painful and debilitating degenerative AAOA only a small proportion of cases require surgical intervention. In this cohort, only 3.70 % of patients required surgery, highlighting the rarity of surgical intervention required in the management of AAOA. Nevertheless, when conducted, atlantoaxial fusion has proved to be efficacious with a low rate of serious complications and the patient self-rated outcome in terms of post-operative visual analog scale score and neck disability index scores indicating a high degree of satisfaction with the procedures. Keywords: Atlantoaxial, osteoarthritis, fusion, transarticular screws.

C1–C2 Transarticular Screw with Sublaminar Wiring for Reducible Atlantoaxial Dislocation: Operative Technique and Surgical Nuances

Abstract Transarticular screw provides rigid C1 C2 fixation. It is associated with robust implant construct and high fusion rates. Combining sublaminar wiring provides rigid three point fixation. This technique can be safely considered in reducible AAD where a wide C2 isthmus along with a normal Vertebral artery course is present. Authors describe the technique in detail with indications, benefits over other similar procedures, short falls and detailed operative steps. “Pearls and Pitfalls” adds a fresh perspective to this less often considered procedure.

Atlas Morphometry: A Radiologic- Anatomical Study

Abstract Introduction: Atlas is an atypical cervical vertebra with unique anatomy and related to many vital structures. Any surgical intervention at this level, especially transpedicular and transarticular screw placement, requires in detail assessment of the structure of the atlas. Certain measurements considered surgically important were measured on computerized tomography (CT) scans and compared with corresponding measurements on dry bones. Methodology: The study was carried out in KVG Medical College and Hospital, Sullia, including 100 CT scans of 43 females and 57 males with a mean age of 31.4 years and 40 dried atlas vertebrae available in the Department of Anatomy. Lengths and widths of superior and inferior articular facets were measured on both CT scans and dry bones and compared. Length, width, and heights of lateral masses, along with height below the posterior arch (HBPA), maximum medialization and cranialization angles were assessed on CT scans. The mean, standard deviation, and significance of differences were calculated using an independent t-test. Results: Mean value and standard deviation were calculated for the measured parameters. Superior and inferior facet measurements were compared between CT scan images and dry bones and no significant difference was found. Conclusion: Morphometric measurements of atlas on CT images are useful for planning of screw fixation surgeries, particularly to avoid injury to vital structures. Values of measurements, especially maximum medialization angle, maximum cranialization angle, and HBPA, are in agreement with other studies and are proposed to be included as part of preoperative workup.

Functional and radiological outcomes following craniovertebral junction surgery.

Craniovertebral junction (CVJ) pathologies include atlantoaxial instability/deformities resulting in myelopathy, respiratory failure, and even death. Here, we describe the indications, preoperative planning, and intra-operative/postoperative complications following surgical management of CVJ anomalies. A prospective analysis of 34 patients with CVJ pathology was evaluated between 2015 and 2022. Their various etiologies included atlantoaxial instability, trauma, tuberculosis, Down's syndrome, Morquio syndrome, os odontoideum, and atlantoaxial abnormalities. Clinical outcomes were assessed using the American spinal injury association (ASIA) impairment scale score and Benzel's modified Japanese Orthopedic Association (mJOA) score. Surgical assessments included length of hospital stay, operative time, blood loss, and intraoperative postoperative complications. Radiological parameters included fusion (i.e., implant loosening/implant failure), preoperative/ postoperative atlanto-dens interval (ADI), clivus canal angle (CCA), and space available for cord (SAC). Five patients were managed conservatively, while 29 patients had surgery. Operations included occipitocervical fusion (14 patients), C1-2 fusion (10 patients), C1-2 transarticular screw fixation (four patients), and one patient underwent anterior corpectomy decompression/fusion. Seven patients had vertebral artery anomalies, and 13 patients had atlantoaxial abnormalities. At the final follow-up, atlantoaxial instability (i.e., mean preoperative ADI of 6.6 ± 2.3 mm) was restored to 4.2 ± 0.6 mm, significant cord compression (i.e., with mean SAC of 8.3 ± 2.9 mm) was relieved to 17.2 ± 1.6 mm, and the mean preoperative CCA (i.e., 130.2 ± 15.3) was improved to 143.3 ± 8.3°. There was also a statistically significant improvement in the ASIA scale and mJOA score. Surgical management of CVJ abnormalities requires expertise and meticulous planning to avoid devastating complications such as wound dehiscence and catastrophic vertebral artery injury.

The Use of Dorsal Bridge Plate Fixation in the Operative Management of Lisfranc Injuries – A Retrospective Cohort Study at Medium Term Follow-Up

IntroductionTraditionally, early surgical management of Lisfranc injuries with transarticular screws (TAS) was deemed to be the optimal treatment. However, concerns of potential iatrogenic articular cartilage disruption has led to discrepancies in opinion amongst surgeons, with many surgeons now utilizing dorsal bridge plates (DBP) for ORIF of Lisfranc injuries. ObjectivesThis study sought to investigate the clinical outcomes at medium-term follow-up of consecutive patients in our institution who underwent ORIF with DBP for Lisfranc injuries. MethodsAll consecutive patients who underwent ORIF with DBPs for Lisfranc injuries were identified. Outcomes of interest included; visual analogue scale (VAS), functional foot index (FFI), American Orthopaedic Foot & Ankle Surgeons (AOFAS) hindfoot scores, and complications. ResultsOverall, 37 consecutive patients (24 males) with a mean age of 34.8 ± 13.0 years underwent ORIF with DBPs for lisfranc injuries. After a mean 48.3 ± 28.7 months, the mean reported AOFAS and FFI scores were 77.4 ± 23.8 and 31.9 ± 32.7 respectively, with satisfactory reported pain scores as measured by VAS post-operatively at rest and whilst walking (2.2 ± 2.5 and 3.1 ± 2.6 respectively). The reported satisfaction rate was 86.5% (32/37). Overall, 25 patients (67.6%) had subsequent removal of metal or were listed for same, 88% (22/25) of whom did so electively in the absence of broken screws or infection. ConclusionThis study found that the use of Dorsal Bridge Plates for Open Reduction and Internal Fixation of Lisfranc Injuries resulted in satisfactory functional outcomes, high rates of patient-reported satisfaction and a low complication rate at medium-term follow-up. Level of EvidenceLevel IV; Retrospective Series of Consecutive Patients

Different C2 screw placement techniques with mobilization of the vertebral artery in high-riding vertebral artery cases: Cadaver dissection.

In neurosurgery, posterior approaches intended at the craniovertebral junction are frequently used. The most popular procedures for treating upper cervical instability are C1 lateral mass, C2 pedicle, and C1-C2 transarticular screw stabilization. Due to their proximity to neural structures and the presence of the high-riding vertebral artery (VA), these techniques are complicated. The risk of VA damage can be decreased by mobilizing the VA. Using cadaveric specimens in this study was aimed to demonstrate C2 pedicle and C1-C2 transarticular screw placement with VA mobilization and a novel C2 inferior corpus screw placement technique. In this study, twelve adult cadaveric specimens and two adult dry cadaveric C2 bones were used with the permission and decision of the University Research Ethics Committee. Colored silicone was injected into the arteries and veins of these twelve cadaveric specimens. Then, muscle dissection was performed stepwise, and the C2 vertebrae of the cadavers were revealed with a surgical microscope. Each specimen and entire stages of the dissections were recorded photographically. After cadaver dissections, screw placement was performed with three different techniques. Finally, radiological imaging was done with fluoroscopy. After dissection, the lateral mass of the C2 vertebra was observed, and lateral to it, the transverse process and foramen were detected with the help of a hook. Next, the posterior wall of the VA groove was removed using a 1 mm thin plate Kerrison rongeur until the VA loop could partially be observed the VA. This enables us to find the top of the loop of the VA and mobilize it inferiorly using a dissector. Following this step, the C1-2 transarticular, C2 pedicle, and the novel C2 inferior corpus screw placement can be performed safely by directly visualizing the artery. Due to the nearby neurologic and vascular structures, placing the C2 pedicle and C1-2 transarticular screw is a challenging procedure, especially in high-riding VA cases. However, it is possible to place the C2 pedicle, C1-2 transarticular, and novel C2 inferior corpus screw after the mobilization of the VA. This study aimed to show all of them together on a cadaver for the first time, to understand the anatomy of the C2 vertebra, and to use screw placement techniques to minimize the risk of complications.

Anterior Transarticular Crossing Screw Fixation for Atlantoaxial Joint Instability: A Biomechanical Study.

To evaluate the biomechanical stability of anterior transarticular crossing screw (ATCS) and compare it with anterior transarticular screw (ATS) which may provide basic evidence for clinical application. Eight human fresh cadaveric specimens (occiput-C4) were tested with 5 conditions including the intact status, the injury status (type II odontoid fracture), the injury+ATS fixation status (traditional bilateral ATS fixation); the injury+unilateral ATCS fixation status; and the injury+bilateral ATCS fixation status. Specimens were applied to a pure moment of 1.5 Nm in flexion-extension, lateral bending, and axial rotation, respectively. The range of motions (ROMs) and the neutral zones (NZs) of C1 to C2 segment were calculated and compared between 5 status. ATS and ATCS fixations significantly reduced the motions in all directions when compared with the intact and injury statues (p < 0.05). In flexion-extension, the ROMs of ATS, unilateral ATCS, and bilateral ATCS were 4.7° ± 2.5°, 4.1° ± 1.9°, and 3.2° ± 1.2°, respectively. Bilateral ATCS resulted in a significant decrease in ROM in flexion-extension when compared with ATS and unilateral ATCS (p = 0.035 and p = 0.023). In lateral bending and axial rotation, there was no significant difference in ROM between the 3 fixations (p > 0.05). Three fixations resulted in similar NZs in all directions (p > 0.05). ATCS is a biomechanically effective alternative or supplemental method for atlantoaxial instability.

Lisfranc Injury: Recent Trends in Management.

Lisfranc injury refers to a group of bony or ligamentous injuries in which one or more of the metatarsals are displaced with respect to the tarsus. These injuries can occur as a result of either high-energy trauma like motor vehicle accidents and falls from height, or low-energy trauma from sports activities. A significant proportion of Lisfranc injuries are missed initially. The effects of delayed and missed diagnosed cases can be devastating as patients may develop progressive midfoot instability, collapse of arch, abduction of forefoot, and post-traumatic osteoarthritis, which can cause chronic pain, stiffness, and foot and ankle complex dysfunction. Favourable outcomes are associated with early diagnosis and prompt treatment. Open reduction and internal fixation (ORIF) with arthrodesis has better results than ORIF alone in functional outcomes. Dorsal bridge plates are currently the preferred mode of fixation due to advantages over trans-articular screws.

Simulated Weightbearing and Articular Injury From Transarticular Screws in a Ligamentous Lisfranc Injury Model.

Transarticular screw fixation is a common surgical treatment for tarsometatarsal ligamentous (Lisfranc) injuries. Iatrogenic damage to articular cartilage from screw placement, however, has been thought to potentially lead to increased risk of tarsometatarsal (TMT) joint arthritis after initial injury. To date, no study has evaluated the effect of weightbearing on articular cartilage after screw fixation. The aim of this study was to create a Lisfranc injury and quantify and compare articular damage due to screw fixation before and after simulated weightbearing. A ligamentous Lisfranc injury was created in 10 cadaveric specimens and treated with transarticular screws. Specimens were cycled for 1000 cycles at 250 N to simulate 2 weeks of physiologic weightbearing. Rotation and diastasis across the Lisfranc complex were measured. Articular injury as a percentage of total articular surface was measured using digital imaging of the first and second TMT joint before and after simulated weightbearing. Comparisons between articular damage were made and statistical analysis was performed. Simulated partial weightbearing increased articular injury 1.44-fold (P < .001). The second metatarsal (M2) showed the greatest increase (1.54-fold, P = .0047), whereas the first (M1) showed the least (1.35-fold, P = .0083). Increases seen at the medial (1.43-fold, P = .0387) and middle cuneiform (1.44-fold, P = .0292) were intermediate between the values seen at M2 and M1. Articular damage from transarticular screw fixation significantly increased after simulated partial weightbearing. This may increase the risk of arthritis and future morbidity when using transarticular screws for the treatment of ligamentous Lisfranc injuries. Iatrogenic damage to articular cartilage due to screw fixation of ligamentous Lisfranc injuries may be increased with weightbearing.

Stress analysis of the screw of atlantoaxial posterior screw fixation C1LM-C2PS and C1LM-C2PARS with and without rod: A FEM based study

Human cervical spine consists of three vertebrae C0-occiput, C1-atlas, & C3-axial in its upper part. The atlantoaxial complex is the most portable segment of the cervical spine and is accountable for half of the flexion, extension, and axial rotation movements of the neck. Atlantoaxial cervical spine injuries are serious injuries since there is a likely risk of harm to the spinal cord. Sustaining stability of the atlantoaxial joint following a neck injury is a difficult task because both vertebrae have complicated anatomy. Thus, the strength of a bone screw is especially significant in the early post-operative stages. Different stabilization procedures have been accounted for C1-C2 injury fixation, out of which fixation with transarticular screws is considered as the gold standard procedure. But screw malposition and high riding transverse foramen of the C2 vertebra are some limitations of this fixation technique. Current FE-based study provides a comparison of the biomechanical stability of the two different atlantoaxial posterior screw fixation techniques (C1Lateral Mass-C2 Pedicle screws, C1Lateral Mass-C2PARS screws).In this work, a C1-C2 cervical spine model of a male patient is developed using MRI CT scan data using a 3-d slicer software and biomechanical stability comparison is done for C1LM-C2PS & C1LM-C2PARS screws fixed once with a supporting posterior screw fixation rod and once without rod under the physiological loading conditions of flexion, extension, lateral bending, and axial rotation using ANSYS WORKBENCH 16.2. The effects of the engaging supporting rod on the cervical spine were evaluated in the form of von-mises stresses induced in screws. Result shows reduction in screw stress values when implanted with supporting rods. C1LM-C2PS screw fixation with rod might be thought of as the best fixation solution for fractured C1-C2 vertebrae as it showed minimum stress values in the analysis as compared to C1LM-C2PARS with and without rod.

Biomechanical properties of different anterior and posterior techniques for atlantoaxial fixation: a finite element analysis

BackgroundMany techniques for atlantoaxial fixation have been developed. However, the biomechanical differences among various atlantoaxial fixation methods remain unclear. This study aimed to evaluate the biomechanical influence of anterior and posterior atlantoaxial fixation techniques on fixed and nonfixed segments.MethodsAn occiput-C7 cervical finite element model was used to construct 6 surgical models including a Harms plate, a transoral atlantoaxial reduction plate (TARP), an anterior transarticular screw (ATS), a Magerl screw, a posterior screw-plate, and a screw-rod system. Range of motion (ROM), facet joint force (FJF), disc stress, screw stress, and bone-screw interface stress were calculated.ResultsThe C1/2 ROMs were relatively small in the ATS and Magerl screw models under all loading directions except for extension (0.1°–1.0°). The posterior screw-plate system and screw-rod system generated greater stresses on the screws (77.6–1018.1 MPa) and bone-screw interfaces (58.3–499.0 MPa). The Harms plate and TARP models had relatively small ROMs (3.2°–17.6°), disc stress (1.3–7.6 MPa), and FJF (3.3–106.8 N) at the nonfixed segments. Changes in disc stress and FJF of the cervical segments were not consistent with changes in ROM.ConclusionsATS and Magerl screws may provide good atlantoaxial stability. The posterior screw-rod system and screw-plate system may have higher risks of screw loosening and breakage. The Harms plate and TARP model may more effectively relieve nonfixed segment degeneration than other techniques. The C0/1 or C2/3 segment may not be more susceptible to degeneration than other nonfixed segments after C1/2 fixation.

Transarticular Fixation Using Bioabsorptive Screws for Cervical Lesions.

Transarticular screw fixation is a method for posterior cervical fixation. It is ergonomic because neither connectors nor rods are needed. Biomechanical studies have shown that its fixation force is not inferior to that of lateral mass screws. More information is needed on the surgical outcome of procedures using bioabsorptive screws. We investigated the long-term surgical and radiological outcomes of posterior cervical decompression and fusion using bioabsorptive screws for transarticular fixation.Of 10 patients who underwent cervical spine transarticular fixation using bioabsorptive screws, nine presented with cervical degenerative spondylosis and one with a traumatic cervical spine injury. The mean postoperative follow-up period was 57.1 months. Transarticular screw fixation was successful in all 10 patients; no intraoperative complications were encountered. Bilateral screw breakage was discovered in a patient with cervical spine instability and associated dystonia due to cerebral palsy; there was no symptom deterioration, facet joint breakage, or instability exacerbation. Facet fusion was obtained in the nine other patients. At the patients' last visit, their clinical symptoms were significantly improved. Whole cervical spine alignment (-4.21 ± 7.2 to -5.2 ± 8.7) and the fused segment angle (mean, -0.1 ± 9.9 to -1.2 ± 13.7) did not significantly worsen postoperatively (mean: -0.1 ± 9.9 to -1.2 ± 13.7). Transarticular fixation using bioabsorptive screws is safe and associated with good long-term outcomes. In patients with exacerbation of local instability after posterior decompression, additional transarticular fixation using bioabsorbable screws is a treatment option.

Long term results and patient reported outcome measures following lisfranc injuries treated with memory staple fixation

IntroductionVarious modalities of fixation have been proposed for Lisfranc injuries. Memory staple fixation offers a simple option for transarticular fixation in suitable fracture configuration with no diaphyseal extension. However there is little evidence available in the literature regarding its efficacy and patient reported outcomes. Aim of the study was to present the long term outcomes of Lisfranc injuries treated with memory staple fixation and patient reported outcomes at average follow-up of four years. MethodThis was a retrospective analysis of all the patients who underwent fixation for Lisfranc injury using shape memory alloy (Nitinol) staples from December 2010 to October 2018. Patient demography, mechanism of injury, classification of Lisfranc injury, duration of followup, complication, revision surgery, implant removal and patient reported outcomes (AOFAS midfoot score) was noted. Results31 patients satisfied the inclusion criteria. Mean age was 50 years and 17 patients were females. 54 % patients reported low to moderate energy trauma which included simple fall from standing height or twisting injury. 28 (90.3 %) had B2 type of fracture pattern. 13 had fixation with staples only, 15 with a staple and home run screw. No patient had primary fusion. One patient had superficial infection treated with antibiotics only. Three patients developed symptomatic arthritis, out of which one proceeded to fusion. Six had implant removal for hardware related symptoms. Average AOFAS midfoot score at average four years follow-up was 77.8 which are satisfactory. ConclusionThis paper highlights good outcome following memory staple fixation for Lisfranc injuries. We believe staples are more suited for the dorsal buttressing that is typically required and provide stable, reproducible fixation Our findings also suggest less need for implant removal compared to transarticular screw or plate fixation though larger studies would be required to make definitive conclusions.

Anterior atlanto-occipital transarticular screw fixation: a biomechanical comparison with posterior fixation techniques.

Atlanto-occipital instability is commonly treated with posterior fixation. However, in patients with congenital or acquired factors, posterior fixation may not be possible. For these situations, a novel anterior atlanto-occipital transarticular screw (AATS) fixation technique has been introduced recently. However, biomechanical study of this technique is lacking. This study was designed to evaluate the biomechanical stability of AATS fixation for the atlanto-occipital joint and compare it with conventional posterior occipitocervical fixation (POCF). Six cadaveric specimens (occiput-C4) were tested in four conditions, including intact, injury, injury + AATS, and injury + POCF states. A pure moment of 1.5 Nm was applied to specimens in flexion, extension, lateral bending, and axial rotation. The range of motion (ROM) and neutral zone (NZ) were calculated and compared from the occiput to C1. The AATS fixation constrained ROMs to 0.4° in flexion (p < 0.001), 0.4° in extension (p < 0.001), 1.0° in lateral bending (p < 0.001), and 0.7° in axial rotation (p < 0.001) when compared with the injury state. In all directions, there was no statistically significant difference observed in ROMs and NZs between AATS fixation and POCF (p > 0.05). This study identified that the novel AATS fixation, as stand-alone anterior fixation, was equivalent to POCF in all directions. The results suggest that anterior transarticular screw fixation is a biomechanically effective salvage technique for posterior atlanto-occipital fixation, and may also serve as supplemental fixation.

TEN-YEAR OUTCOMES OF LISFRANC FIXATION DEMONSTRATES THAT COLUMN INVOLVEMENT PREDICTS OUTCOME

The Lisfranc fracture dislocation of the tarsometatarsal joint (TMTJ) is a complex injury with a reported incidence of 9.2 to 14/100,000 person-years. Lisfranc fixation involves dorsal bridge plating, transarticular screws, combination or primary arthrodesis. We aimed to identify predictors of poor patient reported outcome measures at long term follow up after operative intervention.127 patients underwent Lisfranc fixation at our Level One Trauma Centre between November 2007 and July 2013. At mean follow-up of 10.7 years (8.0-13.9), 85 patients (66.92%) were successfully contacted. Epidemiological data including age, gender and mechanism of injury and fracture characteristics such as number of columns injured, direction of subluxation/dislocation and classification based on those proposed by Hardcastle and Lau were recorded. Descriptive analysis was performed to compare our primary outcomes (AOFAS and FFI scores). Univariate analysis and multivariate regression analysis was done adjusted for age and sex to compare the entirety of our data set. p&lt;0.05 was considered significant. The primary outcomes were the American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Score and the Foot Function Index (FFI).The number of columns involved in the injury best predicts functional outcomes (FFI, P &lt;0.05, AOFAS, p&lt;0.05) with more columns involved resulting in poorer outcomes. Functional outcomes were not significantly associated with any of the fixation groups (FFI, P = 0.21, AOFAS, P = 0.14). Injury type by Myerson classification systems (FFI, P = 0.17, AOFAS, P = 0.58) or open versus closed status (FFI, P = 0.29, AOFAS, P = 0.20) was also not significantly associated with any fixation group.We concluded that 10 years post-surgery, patients generally had a good functional outcome with minimal complications. Prognosis of functional outcomes is based on number of columns involved and injured. Sagittal plane disruption, mechanism and fracture type does not seem to make a difference in outcomes.

Anterior occipital condyle screw placement through the endonasal corridor: proof of concept study with cadaveric analysis.

Odontoidectomy for ventral compressive pathology may result in O-C1 and/or C1-2 instability. Same-stage endonasal C1-2 spinal fusion has been advocated to eliminate risks associated with separate-stage posterior approaches. While endonasal methods for C1 instrumentationand C1-2 trans-articularstabilization exist, no hypothetical construct for endonasal occipital instrumentation has been validated. We provide an anatomic description of anterior occipital condyle (AOC) screw endonasal placement as proof-of-concept for endonasal craniocervical stabilization. Eight adult, injected cadaveric heads were studied for placing 16 AOC screws endonasally. Thin-cut CT was used for registration. After turning a standard inferior U-shaped nasopharyngeal flap endonasally, 4 mm × 22 mm AOC screws were placed with a 0° driver using neuronavigation. Post-placement CT scans were obtained to determine: site-of-entry, measured from the endonasal projection of the medial O-C1 joint; screw angulation in sagittal and axial planes, proximity to critical structures. Average site-of-entry was 6.88mm lateral and 9.74mm rostral to the medial O-C1 joint. Average angulation in the sagittal plane was 0.16° inferior to the palatal line. Average angulation in the axial plane was 23.97° lateral to midline. Average minimum screw distances from the jugular bulb and hypoglossal canal were 4.80mm and 1.55mm. Endonasal placement of AOC screws is feasible using a 0° driver. Our measurements provide useful parameters to guide optimal placement. Given proximity of hypoglossal canal and jugular bulb, neuronavigation is recommended. Biomechanical studies will ultimately be necessary to evaluate the strength of AOC screws with plate-screw constructs utilizing endonasal C1 lateral mass or C1-2 trans-articular screws as inferior fixation points.