C1-C2 Screw Research Articles

Odontoid Fractures: A Review of the Current State of the Art.

Odontoid fractures (OFs) represent up to 15% of all cervical fractures encountered and present most commonly amongst elderly patients, typically in the setting of low energy trauma such as falls. The Anderson and D'Alonzo classification and Roy-Camille subtype description are the most clinically noteworthy descriptions of OFs used. Even though most patients will not present with neurological injury, mechanical instability can occur with type II and type III (Anderson and D'Alonzo) fractures, particularly if the transverse ligament of the atlas is ruptured; however, this is very rare. Conservative treatment is usually employed for type I and type III injuries, and to a varying degree for non-displaced type II injuries. Surgical treatment is typically reserved for type II fractures, patients with neurological injury, and in the setting of other associated fractures or ligamentous injury. Anterior screw fixation is a viable option in the setting of a favorable fracture line orientation in type II fractures, whereas posterior C1-C2 screw fixation is an option for any type II or type III fracture presentation. There is evidence that surgery for type II fractures has higher rates of union and lower mortality than nonoperative treatments. While surgical options have increased over the decades and the management of OF has been optimized by considering fracture subtypes and patient factors, there remains a significant morbidity and mortality associated with OFs. The aging population and changing demographics suggest that there will be an ongoing rise in the incidence of OFs. Therefore, the appropriate management of these cases will be essential for ensuring optimization of health care resources and the quality of life of affected patients.

TO STUDY THE FUNCTIONAL AND RADIOLOGICAL OUTCOMES OF ANKLE ARTHRODESIS WITH CORTICOCANCELLOUS SCREW FIXATION VS INTRAMEDULLARY NAILING

Objective: We aimed to evaluate the functional and radiological outcomes of ankle arthrodesis using corticocancellous screw fixation vs intramedullary nailing. Methods: In our study, 22 cases underwent the procedure. This evaluation was performed based on preoperative radiologic data and at postoperative clinical visits at 2 months, 6 months, and 12 mo required postoperatively. Radiologic outcomes were measured by: (1) Rate of union, (2) Rate of adjacent joint arthritis, and (3) Alignment of the ankle joint. Functional outcomes were measured by using the AOFAS score (American Orthopedic Foot and Ankle Society score). The patients' Subjective assessments were done using the Cumberland Ankle Instability Tool (CAIT). Results: The angle between the tibia's long axis and a line parallel to the talus's long axis is determined in the AP projection. The mean angle was 89.6 degrees (85-100 degrees) in the intramedullary nailing group (IMN group) and 91.4 degrees in the corticocancellous screw group (CC screw). The angle between the tibia's long axis and a line that is perpendicular to the talus’s long axis. The mean angle was 40.5 degrees (30-45 degrees) in the IMN group and 41.6 degrees in the CC screw group. The mean AOFAS score (American Orthopedic Foot and Ankle Society score) was 83.25 in the IMN group and 80.5 in the other group. The mean Cumberland Ankle Instability Tool (CAIT) score was 28 in the IMN group and 27.5 in the other group. All the cases showed bony union except one case, the average time taken for the union was 18.5 w in the IMN group and 20.5 w in the CC screw group. Conclusion: According to our study, all of the patients with normal angles between the tibia's long axis and a line perpendicular to the talus's long axis were obtained in the AP projection, and the angle between the tibia's long axis and a line that is perpendicular to the talus’s long axis. These patients also showed better Cumberland Ankle Instability Tool (CAIT) and AOFAS (American Orthopedic Foot and Ankle Society) scores in both comparison groups.

Comparative study between CC screw and TBW for the treatment of medial malleolus fractures

Comparative study between CC screw and TBW for the treatment of medial malleolus fractures

Comment on 'Role of Biplane Double-Supported Screw Fixation (BDSF) in Management of Fracture Neck Femur and Its Comparison with Conventional CC Screw Fixation'.

Comment on 'Role of Biplane Double-Supported Screw Fixation (BDSF) in Management of Fracture Neck Femur and Its Comparison with Conventional CC Screw Fixation'.

Current insights and surgical interventions in craniovertebral junction instability

Abstract Background: The Craniovertebral Junction (CVJ) is prone to various pathologies, including instability and congenital anomalies. Understanding these conditions and their management strategies is critical for effective treatment. Materials and Methods: A systematic search was conducted in Science Direct and PubMed databases following PRISMA guidelines. Inclusion criteria encompassed studies addressing craniovertebral instability and associated pathologies. Six systematic investigations were assessed for methodological quality. Data extraction involved 702 patients with CVJ issues, among which 129 had related conditions, while 279 displayed normal CVJ. Surgical interventions encompassed various techniques such as C1-C2 fixation, posterior decompression, and screw placements. Results: Among 702 patients studied, atlantoaxial subluxation, basilar invagination, and odontoid fractures were observed in 129 cases. Surgical treatments showed favorable outcomes, with fusion achieved within a year post-surgery for both C1-C2 fixation techniques and posterior decompression strategies. Studies highlighted successful outcomes in cases of cervical myelopathy, especially with early occipitocervical fusion. Conclusion: Managing atlantoaxial instability remains a debated topic, with varying success rates observed in different surgical interventions. Recommendations emphasize the importance of stabilization techniques and imaging modalities for effective preoperative planning and postoperative care. However, limitations in the available data underscore the need for further research to refine treatment strategies for better patient outcomes in this complex area of spinal pathology. Keywords: Craniovertebral junction, atlantoaxial instability, Basilar invagination, fusion, CVJ pathologies

Functional outcome of patients presenting with isolated medial condyle fractures of femur in a tertiary care hospital

Isolated medial condyle fractures of the femur with an intact lateral condyle are a rare entity. These fractures require prompt diagnosis and anatomical restoration of joint surface to prevent post traumatic arthritis. Till date no suitable implant is available for fixation of these fractures. In this study we have used 4.5 recon plates and CC screws to fix these fractures. We aim to study the functional outcome of these fractures in a group of patients fixed with the above implants. The study was conducted in a group of patients presenting with isolated medial condyle fractures of femur in a tertiary care hospital. An ORIF was done and fractures were fixed with recon plates and lag screws and various parameters were evaluated such as range of motion of knee, average time to weight bearing, Lysholm knee scores, pain perception etc 20 patients were evaluated in the age group of 20-70 in a 5 year period. Majority of the patients had a very good functional range of motion of the knee and nearly 75% achieved union by 12-16 weeks. 70% of the patients had a low VAS score. Overall early diagnosis and prompt anatomical restoration of joint surface in isolated medial condyle fractures of femur led to favourable range of motion of knee, early radiological healing and low VAS score.

Posterolateral Paramass Approach to Lesions Located at the Anterior C1-2 Level: A Cadaver Study

A novel posteriolateral surgical approach is described that will provide safe access to intradural and extradural lesions located in the anterior part of the spinal cord (SC) at the C1-2 level and to the odontoid in single session. A total of five cadavers and two dry C1 vertebrae were used in this study. The study involved obtaining computed tomography magnetic resonance imaging scans and magnetic resonance imaging of all cadaver groups before and after the procedures. Group 1: Control; Group 2: Unilateral C1 posterior arch was removed, the inferomedial part of C1 lateral mass was removed, and access the anterior and lateral aspects of the SC. Group 3: In addition, odontoid was removed, Group 4: In addition, unilateral C1- C2 screw was placed. Group 5: In addition, bilateral C1-C2 screw was placed. The median distance from the midpoint of C1 posterior tubercle to vertebral groove which was removed in groups is 21.4 ± 2.88mm. The average width of C1 lateral mass was 13.4±2.4mm. After the lateral mass was drilled, its width decreased to 10,2mm.This area was sufficient to open a surgical corridor and reach the anterior of SC and odontoid. After the procedure, no instability was found in group 2 without instrumentation on computed tomography and magnetic resonance imaging scans. It is possible to access the anterior C1-C2 via a posterolateral paramass approach by drilling 20%-30% of the lateral mass, providing an open pathway for easy intervention in C1-C2 intradural lesions. It is also possible to perform odontoid resection using this approach.

An institutional study on accuracy of freehand cervical C1 C2 screws placement by knock and drill technique in craniovertebral anomalous bony anatomy: An evaluation of more than 600 screws based on SGPGI screw accuracy criteria.

To assess the accuracy of freehand cervical C1 C2 screws placement by knock and drill (K and D) technique in craniovertebral anomalous bony anatomy. From January 2017 to December 2022, 682 consecutive C1 C2 screws in 215 patients with craniovertebral junction (CVJ) anomalies were enrolled. All patients underwent posterior fixation with K and D technique without any fluoroscopic guidance. The patient's demographic details, clinical details, radiological details, major intraoperative events, and postoperative complications were noted. The screws malposition grades and direction on CT images in the axial and sagittal plane were defined as new per proposed "SGPGI accuracy criteria." All patients had a clinical evaluation at 3-month follow-up. Total 682 C1, C2 screws were placed in 215 patients for CVJ anomalies using K and D technique. The accuracy of screws placement by freehand technique was 84.46% (576/682). So with technique explained the rate of malplacement in simple (16.35%) and complex (15.19%) groups were almost comparable and comparison difference was not significant (P = 0.7005). The freehand technique, as described, is effective in cases of anomalous bony anatomy, and it is mandatory in complex CVJ anomalies. The accuracy of screw placement and VA injury is comparable with major studies. This technique is supposedly cost-effective and less hazardous to both health-care workers and patients.

Role of Biplane Double-Supported Screw Fixation (BDSF) in Management of Fracture Neck Femur and Its Comparison with Conventional CC Screw Fixation.

The aim of this study is to evaluate comparative biomechanical fixation provided with the BDSF method with the conventional CC screw fixation for treatment of femoral neck fractures with three parallel cannulated screws. This is a prospective cohort study. There were two teams of surgeons out of which one team operated the patients with BDSF technique and second with conventional CC screw fixation technique; thus, the patients were randomly distributed into two groups. Patients were included in the study as per the following inclusion and exclusion criteria. Union was achieved in 15 (83.33%) patients managed by conventional CC screw technique, while union was achieved in 11 (91.67%) patients managed by BDSF technique in the present study. The average Harris hip score in present study was 90 score in patients managed by BDSF technique, while the average Harris hip score in present study was 80 score in patients managed by BDSF technique. Both BDSF and conventional CC screw fixation are good fixation methods for fracture neck of femur. But functional outcome and fracture union rates are better with BDSF Technique. Although, there are some minor problems noted in BDSF technique such as outer cortical fracture at the entry point of beam screw and opening up of anterior cortex of oblique fracture patterns. Thus, BDSF method provides reliable fixation in which early mobilization and partial weight bearing of the patient may be allowed.

Orif of lateral Hoffa's fracture with irreducible patella dislocation and incarcerated patella in lateral Hoffa's fragment: rare injury presentation

Majority of lateral Hoffa fracture are associated with knee injury. Presenting a case of 30-years-old gentleman who presented with pain, swelling, deformity in knee of right side after road traffic accident. On local examination there was marked swelling with inability to palpate patella, inability to flex knee. On clinical examination, there was patella dislocation as it was not in place and unable to reduce. Radiological investigation showed a lateral Hoffa's fracture with dislocation of patella and patella being incarcerated in Hoffa fragment. Operative and follow up: Patient was operated by open reduction of patella dislocation and CC screw fixation for lateral Hoffa fracture. On six weeks follow up normal ROM achieved. Patient was surgically treated to relocate locked patella fragment in Hoffa's fragment and fix Hoffa's fragment and achieved good range of motion.

Comparison of intraoperative CT- and cone beam CT-based spinal navigation for the treatment of atlantoaxial instability

BACKGROUND CONTEXTDue to the complexity of neurovascular structures in the atlantoaxial region, spinal navigation for posterior C1–C2 instrumentation is nowadays a helpful tool to increase accuracy of surgery and safety of patients. Many available intraoperative navigation devices have proven their reliability in this part of the spine. Two main imaging techniques are used: intraoperative CT (iCT) and cone beam computed tomography (CBCT). PURPOSEComparison of iCT- and CBCT-based technologies for navigated posterior instrumentation in C1-C2 instability. STUDY DESIGNRetrospective study. PATIENT SAMPLEA total of 81 consecutive patients from July 2014 to April 2020. OUTCOME MEASURESScrew accuracy and operating time. METHODSPatients with C1–C2 instability received posterior instrumentation using C2 pedicle screws, C1 lateral mass or pedicle screws. All screws were inserted using intraoperative imaging either using iCT or CBCT systems and spinal navigation with autoregistration technology. Following navigated screw insertion, a second intraoperative scan was performed to assess the accuracy of screw placement. Accuracy was defined as the percentage of correctly placed screws or with minor cortical breach (<2 mm) as graded by an independent observer compared to misplaced screws. RESULTSA total of 81 patients with C1–C2 instability were retrospectively analyzed. Of these, 34 patients were operated with the use of iCT and 47 with CBCT. No significant demographic difference was found between groups. In the iCT group, 97.7% of the C1–C2 screws were correctly inserted; 2.3% showed a minor cortical breach (<2 mm); no misplacement (>2 mm). In the CBCT group, 98.9% of screws were correctly inserted; no minor pedicle breach; 1.1% showed misplacement >2 mm. Accuracy of screw placement demonstrated no significant difference between groups. Both technologies allowed sufficient identification of screw misplacement intraoperatively leading to two screw revisions in the iCT and three in the CBCT group. Median time of surgery was significantly shorter using CBCT technology (166.5 minutes [iCT] vs 122 minutes [CBCT]; p<.01). CONCLUSIONSSpinal navigation using either iCT- or CBCT-based systems with autoregistration allows safe and reliable screw placement and intraoperative assessment of screw positioning. Using the herein presented procedural protocols, CBCT systems allow shorter operating time.

Minimally Invasive Surgical Technique through a Natural Anatomical Corridor for C1-C2 Screw Fixation

Objective: The atlantoaxial complex exhibits unique morphological and biomechanical characteristics. Trauma, tumors, and inflammatory or congenital diseases may compromise the stability of this joint. The purpose of this study was to describe a minimally invasive surgical (MIS) technique for C1-C2 fixation through an anatomical corridor and to analyze the clinical, surgical, and fusion outcomes using this approach over a 15-year period.Methods: We present a MIS technique utilizing a natural anatomical corridor for C1-C2 screw fixation, which has been used at our institution since 2007. We analyzed the demographic characteristics and clinical results of the patients who underwent this procedure.Results: Forty-seven patients underwent C1-C2 MIS screw fixation during the study period, with 24 male patients and a median age of 66 years. The indication for surgery was atlantoaxial subluxation in 60% of cases and odontoid fracture in 23%. The median surgery duration was 130 minutes, with a median blood loss of 300 mL. There were no intraoperative complications, and only one patient presented with a superficial wound infection, which was successfully treated with antibiotics.Conclusion: The minimally invasive approach through a natural anatomical corridor to fuse the atlantoaxial joint using C1 lateral masses and C2 pedicle screws bilaterally has been demonstrated to be safe and effective. Preserving the occipital-cervical tension band provides additional biomechanical stability to the construct.

Atlantoaxial Stabilization Using C1 Lateral Mass and C2 Pedicle/Translaminar Screw Fixation by Intraoperative C1- and C2-Direct-Captured Navigation with Preoperative Computed Tomography Images.

In C1-C2 posterior fixation, the C1 lateral mass and C2 pedicle/translaminar screw insertion under spine navigation have been used frequently. To avoid the risk of neurovascular damage in atlantoaxial stabilization, we assessed the safety and effectiveness of a preoperative computed tomography (CT) image-based navigation system with intraoperative independent C1 and C2 vertebral registration. It is ideal when a reference frame can be linked directly to the C1 posterior arch for C1-direct-captured navigation, but there is a mechanical challenge. A new spine clamp-tracker system was implemented recently, which allows reliable C1- and C2- direct-captured navigation in nine patients with traumatic C2 fractures. In this way, there was no misalignment of C1-C2 screws. C1 lateral mass screws were used except for one case, and translaminar screws were primarily used as an anchor for C2. The C1 lateral mass screw locations, which are 19 mm laterally from the C1 posterior arch's center, are taken to be constant. However, there is one unusual circumstance in which using a C1 laminar hook instead of a C1 lateral mass screw appears to be a beneficial substitute. The increase of surgical accuracy for posterior C1-C2 screw fixation without cost constraints is significantly facilitated by intraoperative C1- and C2-direct-captured navigation with preoperative computed CT images.

A COMPARATIVE STUDY OF USING DYNAMIC HIP SCREW VS MULTIPLE CANCELLOUS SCREW FIXATION IN FRACTURE NECK OF FEMUR IN YOUNGADULTS

Introduction: Incidence of fracture of neck of femur is increasing in young adults. Dynamic Hip Screw with a derotation screw or CC screw is used in operation to reduce and stabilize femoral neck fractures. the commonest complications of intracapsular fractures of neck femur are non-union and avascular necrosis. Material And Methods: The study included 40 patients with history of trauma and diagnosed with fracture neck of femur. After thorough evaluation of patient , Pre-operative radiograph of pelvis with both hips were taken. Routine preoperative profile was done in each patient, along with pre-anesthetic check-up. Follow-up X-rays were taken at each follow-up, which were scheduled at 6 weeks, 3 months, 6 months and at 12 months. Functional and radiological outcome were assessed by scoring Modified Harris Hip Score Observation And Results At 12 months: The mean Harris Hip Score in Group 1 was 84.69 ± 4.51 and in Group 2 it was 90.68 ± 2.54. The mean Harris Hip score at 12 months was significantly higher in Group 2 as compared to Group 1 (P=0.001). Conclusion: When it came to treating fractures of the neck of the femur in young adults, our research found that dynamic hip screw fixation performed better than cancellous screw fixation. In terms of functional outcome, the dynamic hip screw had a higher Harris Hip Score and a lower rate of avascular necrosis. Based on the findings of this study, we recommend using a dynamic hip screw rather than a cancellous screw to fix a fracture of the neck of the femur. We recommend larger studies because there is a lack of research comparing these two fixation modalities.

Comparing the Efficiency of the Femoral Neck System and the Cannulated Compression Screw in Treating Femoral Neck Fractures in Patients Who Are Young and Middle-aged Indian Population

Background: There are no long-term studies regarding the clinical effectiveness of a novel fixation technique (femoral neck system [FNS]) for femoral neck fractures. The primary aim of this study was to compare the effectiveness of two internal fixation techniques (FNS and cannulated compression screw [CCS]) for treating femoral neck fractures in individuals between the ages of 20 and 40 years. Materials and Methods: Data of patients who underwent internal fixation surgery for femoral neck fractures in our hospital between January 2018 and January 2020 with CCS and between January 2020 and January 2022 with FNS were retrospectively evaluated. The groups of CCS and FNS were separated based on the various internal fixation techniques. Demographics about all patients, including sex, age, body mass index, and fracture type were recorded. Pre-operative and 1-year post-operative follow-up of patients was to assess femoral neck shortenings and the Harris Hip score was used to evaluate joint function. Post-operative complications such as femoral head necrosis, non-union, and femoral neck shortening were noted. Results: 30 patients each of CCS and FNS system fixation were enrolled in the study. The male-to-female ratio was 21:9 and 18:12 for CCS and FNS, respectively. The average age of both groups was around 30 years. Compared to patients treated with CC screws, patients who had FNS treatment required less time to recuperate and resume normal activities. The HSS score improvement at 2 weeks and 12 weeks was significantly better in the FNS system than CCS fixation. There was improvement in flexion, abduction, and external rotation range of motion in FNS compared to CCS. There was no statistically significant difference between the two groups in the incidence of femoral head necrosis or fracture non-union following surgery. Conclusion: Patients treated with FNS for femoral neck fractures in the age range of 20–40 years can achieve better hip scores than CCS fixation and also have improved range of motion in flexion, abduction, and external rotation. Keywords: Femoral neck system, cannulated cancellous screw, femoral neck fractures, harris hip score

Comparison of functional outcome between the SHS and CC screws for fixation of fracture involving neck of femur in young adults: A prospective study

Comparison of functional outcome between the SHS and CC screws for fixation of fracture involving neck of femur in young adults: A prospective study

Nuance in Craniovertebral Junction Surgical Approach for Posterior C1-C2 Harms Stabilization: "Window Transposition" of the External Vertebral Venous Plexus for Bloodless C1 Lateral Mass Screw Insertion: Anatomical Aspects and Technical Notes.

Atlas and axis instrumentation may be necessary in cases of several craniocervical junction pathologies. According to the Harms technique, C1-C2 polyaxial screws are inserted respectively in the C1 lateral masses and in C2 pedicles. C1 lateral mass screw insertion requires the careful subperiosteal dissection of the posterior elements of C1, the identification of the screw entry point by the downward distraction of C2 nerve root, and the cautious sparing of the overlying posterior external vertebral venous plexus (peVVP), whose bleeding, obstructing the surgical field, is sometimes barely controlled by hemostatic agents and swabbing. The authors describe in detail the anatomical aspects of an alternative surgical technique developed for the microsurgical transposition of the C1-C2 interposed external vertebral venous plexus in the case of Harms C1-C2 screw stabilization. The longitudinal median incision of the atlantoaxial membrane, followed by bilateral subperiosteal dissection and microsurgical section respectively at the inferior borders of the C1 laminae and at the superior borders of the C2 laminae, allows, as a "window opening," the symmetrical mediolateral transposition of the peVVP. This procedure provides a faster and cleaner anatomical exposition of the posterior surface of the C1 lateral mass and the C2 isthmus, preventing troublesome intraoperative venous bleeding that hinders C1 lateral mass screw insertion.

Functional outcome of displaced femoral neck fractures in young patients treated by dynamic hip screw with CC screws

Background: Although femoral neck fractures are common in elderly individuals, it is an uncommon occurrence in young patients. It is crucial to achieve anatomical reduction as well as stable fixation so as to avoid complications in young individuals who are expected to have considerable functional demand in post-surgical period. Dynamic hip screws are commonly used for internal fixation of these fractures. Although satisfactory functional outcomes have been reported in the patients treated by DHS, complications such as malunion and osteonecrosis remain an area of concern. Aims and Objectives: The aims of the study were to study the functional outcome of young patients with femoral neck fractures treated by DHS with CC screws and to study the complications in young patients with femoral neck fractures treated by DHS with CC screws. Materials and Methods: This was a prospective cohort study in which 80 young adults (below the age of 45 years) having femoral neck fractures and treated by DHS with 2CC screws were included in this study on the basis of a predefined inclusion and exclusion criteria. Gender and distribution, nature of injury, type of fracture, functional outcome, and complications were studied in studied cases. Open reduction and internal fixation was done using dynamic hip screw. The functional outcome was assessed using modified Harris hip score. All patients were assessed for complications such as non-union, malunion, and osteonecrosis. Statistical analysis was done using SSPS 21.0 software and P&lt;0.05 was taken as statistically significant. Results: Out of 80 studied cases having femoral neck fractures, there were 54 (67.50%) males and 26 (32.50%) females with an M: F ratio of 1:0.48. The mean age of male and female patients was found to be 38.37±4.62 and 38.80±4.97 years, respectively. The most frequent cause of fracture was fall from height (48 cases) followed by road traffic accident (31 cases). Forty-six patients had complete fracture with partial displacement (Type III) and remaining 34 patients had complete fracture with total displacement (Type IV). Associated injuries were seen in 9 (11.25%) patients. Nine (11.25%) cases of avascular necrosis of femoral head were seen in our study. Surgery more than 48 h after injury and complete fracture with total displacement were associated with increased risk of avascular necrosis of femoral head (P&lt;0.05). Conclusion: Femoral neck fractures in young patients treated by dynamic hip screws with CC screws have found to have excellent functional results in majority of cases. The complications such as osteonecrosis of femoral head can be minimized by decreased time duration between fracture and surgical intervention.

Referencing for anterior atlantoaxial trans-articular osteosynthesis: a radiological study and proposal of a decisional algorithm.

Anterior trans-articular C1-C2 screw placement can be considered as a surgical alternative in different conditions affecting the atlantoaxial region. While its rigidity is similar to posterior Magerl and Harms techniques, it also provides some surgical advantages. However, the literature lacks papers exhaustively describing indication criteria, surgical steps, and pitfalls. This is a radiological study on 100 healthy subjects. Thin-layer CT scans of the craniovertebral junction were retrieved from the institutional database. The coronal inclination of the C1-C2 joint rim and the depth of the entry point of the screw with respect to the anterior profile of C2 were measured. The antero-posterior and the medio-lateral surgical corridors for the screw placement, and the wideness of the target area on the upper surface of C1 were also measured. The multivariate analysis showed that the coronal inclination of the C1-C2 articular joint rim strongly influences the surface extension of the C1 target area; the depth of the entry point and the C1-C2 articular rim inclination seem to be independent factors in influencing both the medio-lateral and the antero-posterior surgical corridors wideness. A decisional algorithm on whether to perform an anterior or posterior approach to the atlantoaxial region was also proposed. We can conclude that, as much as the C1-C2 articular rim is tending to the horizontal line, and as deeper is the entry point of the screw on the anterior profile of C2, as easier the anterior C1-C2 trans-articular screw placement will result.

Accuracy and Safety of Robot-Assisted versus Fluoroscopy-Guided Posterior C1 Lateral Mass and C2 Pedicle Screw Internal Fixation for Atlantoaxial Dislocation: A Preliminary Study.

Objective To compare the accuracy, efficiency, and safety of robotic assistance (RA) and conventional fluoroscopy guidance for the placement of C1 lateral mass and C2 pedicle screws in posterior atlantoaxial fusion. Methods The data of patients who underwent posterior C1–C2 screw fixation (Goel-Harm's technique) in our hospital from August 2014 to March 2021 were retrospectively evaluated, including 14 cases under fluoroscopic guidance and 11 cases under RA. The hospital records, radiographic results, surgical data, and follow-up records were reviewed. Accuracy of screw placement was assessed using the Gertzbein and Robbins scale, and clinical outcomes were evaluated by Japanese Orthopedic Association (JOA) score, visual analogue scale (VAS), modified MacNab criteria, and postoperative complications. Results Baseline characteristics of both groups were similar. The mean estimated blood loss in the fluoroscopic guidance and RA groups was 205.7 ± 80.3 mL and 120.9 ± 31.9 mL, respectively (p = 0.03). The mean surgical duration was 34 min longer with RA compared to that performed with free-hand (FH) method (p = 0.15). In addition, lower intraoperative radiation exposure was detected in the RA group (12.4 ± 1.4 mGy/screw) versus the FH (19.9 ± 2.1 mGy/screw) group (p = 0.01). The proportion of “clinically acceptable” screws (graded 0 and I) was higher in the RA group (93.2%) than that in the FH group (87.5%, p = 0.04). There was no significant difference in the increase of JOA score and decrease of VAS score between the two surgical procedures. Furthermore, there were no significant differences in overall clinical outcome between the two groups and no neurovascular complications associated with screw insertion. Conclusions RA is a safe and potentially more accurate alternative to the conventional fluoroscopic-guided FH technique for posterior atlantoaxial internal fixation.