Transarticular screw fixation for osteoarthritis of the atlanto axial segment

Athrodesis of the lateral atlanto-axial joint for the relief of neck pain and cervicogenic headache

BACKGROUND

Osteoarthrosis of the lateral atlanto-axial joint (LAAJ) may be a cause of upper neck pain and headache. Intra-articular injection of steroids may provide only short-lasting relief. For intractable pain, arthrodesis of the joint might be considered.

OBJECTIVE

To determine the success rates of arthrodesis of the lateral atlanto-axial joint for relieving neck pain and disability.

DESIGN

Practice audit.

SETTING

Private practice of senior author.

SUBJECTS

Prospective series of 23 consecutive patients.

METHODS

Outcomes were measured using a numerical rating scale for neck pain, and the Neck Disability Index for disability. Success rates were calculated for various degrees of improvement of neck pain at long-term follow-up (8-40 months), and for achieving various combinations of improvement of both neck pain and disability.

RESULTS

Complete relief of pain was achieved in 40% of patients, with a further 40% achieving at least 50% relief. At long-term follow-up, 30% of patients had no neck pain and no disability, and a further 25% had only minimal pain, minimal disability, or both.

CONCLUSIONS

The present study did not corroborate earlier studies that claimed outstanding outcomes for arthrodesis of the LAAJ, but its outcomes are consonant with more recent studies that provided transparent outcome data. These studies provide Pain Physicians with empirical data on success rates and outcomes, upon which they can base their consideration of referral for arthrodesis.

Lisfranc Sports Injuries: What Do We Know So Far?

Lisfranc sports injuries include tarsometatarsal joint injuries, which may be accompanied by fractures. They most commonly occur due to a blow or axial force. The aim of this review is to assess the current standards for surgical intervention in Lisfranc injuries resulting from sports-related accidents. This evaluation will cover the timing of treatment, the recovery process, and the appropriate timing for a return to normal sporting activities. This research was done via an analytical review of current literature. Methods included a structured search strategy on PubMed, Science Direct, and Google Scholar. The collated literature was processed using formal inclusion or exclusion, data extraction, and validity assessment. Joint involvement and severity were taken into account while classifying Lisfranc injuries. The primary fixation and fusion techniques for Lisfranc injuries were compared, and the surgical management of these injuries was examined in all of the literature. Treatment recovery times were examined, and the results were talked about. A variety of injuries, from minor sprains to serious fractures and rips, make up Lisfranc injuries. Although open reduction internal fixation (ORIF) in combination with primary arthrodesis (PA) is now thought to be the optimum course of treatment, its acceptance has increased. Patients with Lisfranc injuries can usually expect excellent outcomes and the return of joint function to its pre-injury form if the injury is appropriately assessed and treated. Lisfranc injuries are manageable and have a good recovery time if not neglected. The outcomes of management and surgical options are also quite satisfactory.

Assessment of atlantoaxial rotation: how accurate is clinical measurement? a comparative study of cervical range of motion using MRI and standard orthopedic techniques

PURPOSE

Measurement of neck rotation is currently reliant on radiologic imaging. Given the radiation exposure for CT imaging and the additional inconvenience for the patients, an alternative assessment is needed. Goniometers are comfortably to use and easy to access, also for private consulting. The aim of this study was the assessment of whether a handheld goniometer can be used for accurately measuring the rotation of C1-C2.

METHODS

Clinical measurement of rotation was taken in flexed position of the neck. As comparison functional MRI was used. The measured rotation of C1-C2 was compared to identify the accuracy of the goniometer, in comparison to functional MRI scan.

RESULTS

Analysis of accuracy using a goniometer and dynamic MRI to assess C1-2 axial rotation showed significant differences for absolute values, but not regarding the percentage of rotation compared to total neck rotation.

CONCLUSION

The goniometer is exact to impartially determine the percentage contribution of C1-2 rotation to total neck rotation.

Factors associated with the increased risk of atlantoaxial osteoarthritis: a retrospective study

Purpose Atlantodens osteoarthritis and atlantoaxial osteoarthritis cause neck pain and suboccipital headaches. Currently, knowledge on the risk factors for atlantoaxial osteoarthritis is lacking. This study aimed to investigate the factors related to the increased risk of atlantoaxial osteoarthritis. Methods We analyzed computed tomography (CT) images of the upper cervical spine of 1266 adult trauma patients for whom upper cervical spine CT was performed at our hospital between 2014 and 2019. The degree of atlantoaxial osteoarthritis was quantified as none-to-mild (not having osteoarthritis) or moderate-to-severe (having osteoarthritis). Risk factors associated with atlantoaxial osteoarthritis were identified using univariate and multivariable logistic regression analyses. Results The study group included 69.4% men, and the overall average age of the study population was 54.9 ± 20.4 years. The following factors were independently and significantly associated with atlantoaxial osteoarthritis in the multivariable logistic regression analysis: age in the sixth decade or older (odds ratio [OR], 20.5; 95% confidence interval [CI], 6.2‒67.2, p < 0.001), having calcific synovitis (OR, 4.9; 95% CI, 2.4‒9.9, p < 0.001), women sex (OR, 3.3; 95% CI, 1.9‒5.7, p = 0.002), and not having atlantodens osteoarthritis (OR, 2.1; 95% CI, 1.2‒3.8, p = 0.014). Conclusion In the multivariable logistic regression analysis, age in the sixth decade or older, calcification of the transverse ligament, being women, and not having atlantodens osteoarthritis were found to be significantly associated with atlantoaxial osteoarthritis. Delayed diagnosis and treatment can be avoided by focusing on these risk factors.

Research Progress of Atlantoaxial Osteoarthritis: A Narrative Literature Review

OBJECTIVE

The purpose of this review was to consolidate the current literature related to atlantoaxial osteoarthritis (AAOA) and improve the systematic understanding of this clinical syndrome among spine surgeons.

METHODS

Articles reviewed were searched in PubMed, Ovid MEDLINE, and EMBASE using search terms: [("C1-C2" OR "C1-2" OR "atlantoaxial" OR "atlanto-axial" OR "C2" OR "C1" OR "atlas" OR "axis") AND ("osteoarthritis")]. All articles of any study design discussing on AAOA were considered for inclusion. Two independent authors read article titles, abstracts and the included appropriate articles. The relevant articles were studied in full text.

RESULTS

A total of 54 literatures were reviewed and consolidated in this narrative review. These articles are roughly divided into the following five subcategories: (1) epidemiology and etiology, (2) clinical presentation, (3) radiographic findings, (4) conservative treatment and (5) surgical indications and treatment options.

CONCLUSION

AAOA was a clinically common but often overlooked syndrome characterized by persistent occipitocervical pain. The most common cause of AAOA was joint degeneration, which was closely related to age and occupation. Initial treatment for AAOA was conservative. Atlantoaxial fusion was an option for patients with severe pain who unresponsive to conservative management.

Patient-rated outcome after atlantoaxial (C1-C2) fusion: more than a decade of evaluation of 2-year outcomes in 126 patients

INTRODUCTION

Various surgical techniques have been introduced for atlantoaxial (C1-C2) fusion, the most common being Magerl's (transarticular) or the Harms/Goel screw fixation. Common indications include degenerative osteoarthritis (OA), trauma or rheumatoid arthritis (RA). Only few, small studies have evaluated patient-reported outcomes after C1-C2 fusion. We investigated 2-year outcomes in a large series of consecutive patients undergoing isolated C1-C2 fusion.

METHODS

We analysed prospectively collected data (2005-2016) from our Spine outcomes database, collected within the framework of EUROSPINE's Spine Tango Registry. It included 126 patients (34 (27%) men, 92 (73%) women; mean (SD) age 67 ± 19 y) who had undergone first-time isolated C1-C2 fusion (61% Magerl, 39% Harms(-Goel)) at least 2 years ago for OA (83 (66%)), RA (20 (16%)), fracture (15 (12%)) or other (8 (6%)). Patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10) and various single item outcomes.

RESULTS

Questionnaires were returned by 118/126 (94%) patients, 2 years post-operative. Mean COMI scores showed a significant reduction from baseline: 6.9 ± 2.4 to 2.7 ± 2.5 (p < 0.0001). Overall, 75% patients achieved the MCIC of ≥ 2.2 points reduction in COMI and 88% reported a good global outcome. 91% patients were satisfied/very satisfied with their care. Self-reported complications were declared by 16% patients and further surgery at the same segment, by 2.5%.

CONCLUSION

In this large series with almost complete follow-up, C1-C2 fusion showed extremely good results. Despite the complexity of the intervention, outcomes surpassed those typically reported for simple procedures such as ACDF and lumbar discectomy, suggesting reservations about the procedure should perhaps be reviewed.

Improvements in Neck Pain and Disability Following C1-C2 Posterior Cervical Instrumentation and Fusion for Atlanto-Axial Osteoarthritis

OBJECTIVE

Symptomatic Atlanto-axial (C1-2) osteoarthritis (AAOA) is a common phenomenon in elderly patients; however, there is a paucity of data on the effectiveness of posterior atlanto-axial fusion (PAAF) for this condition. To this end, here we assess changes in patient-reported outcomes and neck-related disability in adult patients undergoing PAAF for symptomatic C1-2 AAOA.

METHODS

In this retrospective study, the clinical records of consecutive patients with symptomatic AAOA who underwent PAAF between 2004 and 2017 were reviewed. Patient demographics, comorbidities, intraoperative and postoperative variables, and complication rates were collected. Neck Disability Index (NDI) scores were recorded at baseline and 6 weeks, 6 months, 1 year, and 2 years postoperatively.

RESULTS

Forty-two patients (average age, 72.04 ± 8.56 years; 26.19% males) met the study's inclusion criteria. In this cohort, 19.04% had previous subaxial cervical spine surgery, 35.71% had a history of smoking (all had stopped smoking before surgery), and 11.90% had type II diabetes. At baseline, the majority of patients had a normal neurologic exam. The average preoperative NDI score was 26.88 ± 24.85, which improved to 10.59 ± 14.88 at the 1-year follow-up and 13.20 ± 14.96 at the 2-year follow-up (P = 0.004). At baseline, 18% of the patients reported severe disability based on NDI score; this percentage decreased to 2% at 1 year and 0 at 2 years (P = 0.01). Importantly, a high percentage (11.90%) of patients had undergone previous subaxial cervical fusion for their pain due to a mistaken diagnosis for this condition, without symptom relief.

CONCLUSIONS

In appropriately selected patients, PAAF may decrease neck pain and improve functional disability in patients with AAOA. Future prospective longitudinal studies are needed to corroborate these findings.

Occipital Condyle Screw Placement in Patients with Chiari Malformation: A Radiographic Feasibility Analysis and Cadaveric Demonstration

OBJECTIVE

Patients who undergo decompression surgery for Chiari malformation frequently require occipitocervical fixation. This is typically performed with occipital plates, which may cause intracranial injuries due to multiple fixation points. We undertook this study to assess the feasibility of occipital condyle (OC) screw placement as an alternative method of occipitocervical fixation in this patient population.

METHODS

Using a cadaveric model with navigational assistance, we performed the complete surgical procedure for occipitocervical fixation with OC screws. We then performed a morphometric analysis using measurements from computed tomography scans of 49 patients (32 adult, 17 pediatric) who had undergone occipitocervical fusion with instrumentation following decompression surgery for Chiari malformation. Bilateral morphometric data were analyzed for the adult and pediatric subgroups separately, as well as for the overall group.

RESULTS

The surgical procedure was successfully performed in the cadaveric model, demonstrating the feasibility of the proposed method. Ninety-eight OCs were studied in the morphometric analysis, and 80 (81.6%) met our eligibility criteria for OC screw placement. However, in 14.1% of adult OCs and 26.5% of pediatric OCs studied, placement of condylar screws would have been challenging or unsafe, according to our criteria.

CONCLUSIONS

Our findings suggest that OC screws provide a useful option for occipitocervical fixation in a substantial proportion of patients with Chiari malformation. However, rigorous preoperative analysis would be essential to identify appropriate candidates for this technique and exclude those in whom it should not be attempted. Additional study is warranted.

Clinical and radiological outcomes of image guided posterior C1-C2 fixation for atlantoaxial osteoarthritis (AAOA)

Background

Atlantoaxial (C1-C2) osteoarthritis (AAOA) causes severe suboccipital pain exacerbated by lateral rotation. The pain is usually progressive and resistant to conservative therapy. Posterior fusion surgery is performed to stabilise the C1-C2 segment. This is the first Australian study reporting the outcome of posterior atlantoaxial fixation including hybrid fixations performed for AAOA.

Methods

All patients who underwent posterior atlantoaxial fixation surgery for AAOA from 2005 to 2015 at our institutions were enrolled (N=23). Patient demographics and surgical technique were recorded. These techniques included transarticular screw (TAS) fixation using image guidance with iliac crest bone graft and supplemental posterior Sonntag wiring, or C1-C2 lateral mass fixation (Harms technique). Some patients required a combination of fixation due to anatomical variation. Primary outcome measures including patient satisfaction, pain, disability scores and range of motion were recorded for all patients pre- and post-operatively. Post-operative assessment was supplemented with CT and X-ray imaging.

Results

Twenty-three patients (19 women, 4 males, mean age 71.8±6.3 years) underwent surgical fixation. Eight underwent TAS fixation, 8 had Harms fixation, and 7 had a hybrid fixation. All patients reported statistically significant improvement in pain scores [Visual Analogue Scale (VAS) 9.4 pre-op compared to 2.9 post-op, P<0.005]. Disability scores [Neck Disability Index (NDI)] were statistically significantly reduced from 72.2±12.9 pre-operatively to 18.9±11.9 post-operatively, P<0.005. Mean follow-up was 55.3±36.1 months. Results did not vary according to the construct type. Ninety-five point five percent of patients showed radiographic evidence of fusion. Ninety-one percent of patients said they would undergo the surgery again.

Conclusions

Posterior atlantoaxial fixation with TAS and Harms constructs are highly effective for the surgical treatment of intractable neck pain secondary to atlantoaxial lateral mass osteoarthritis (AAOA). Surgery offers a high rate of symptom relief. If anatomical variability exists, both transarticular and pedicle screw fixation could be safely used in the same patient.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Lateral Atlantoaxial Osteoarthritis: A Narrative Literature Review

Lateral atlantoaxial osteoarthritis (AAOA), or C1-C2 lateral mass arthritis (LMA), is an unfamiliar degenerative cervical disease with a clinical presentation that markedly differs from subaxial spondylosis. The prevalence of LMA in the nonsurgical outpatient setting is 4%. Risk factors include age and occupation. The typical patient is between 50 and 90 years old, presents with upper cervical or occipital pain, has limited rotation, and has pain provocation during passive rotation to the affected side. Pain stems from degeneration of the lateral C1-C2 articulation and may be referred or radicular, through the greater occipital nerve. Although there is no consensus on diagnostic work-up, the disease is classically seen on the open-mouth odontoid radiograph. Computerized tomography, magnetic resonance imaging, bone scan, and diagnostic injections are also useful. Initial treatment is conservative, and upwards of two-thirds of LMA patients obtain lasting relief with noninvasive measures and injections. In patients with severe, recalcitrant pain, limited C1-C2 fusion offers satisfactory and reliable relief. The goals of this review article are to provide a synthesis of the literature on LMA, to offer a treatment approach to LMA, and to identify problems with the current state of knowledge on LMA.

Outcomes Following Arthrodesis for Atlanto-Axial Osteoarthritis

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

We set out to evaluate the radiographic and patient-reported outcomes following C1-C2 arthrodesis for atlantoaxial osteoarthritis (AAOA) using modern instrumentation and techniques.

SUMMARY OF BACKGROUND DATA

Few studies have evaluated outcomes following C1-C2 arthrodesis for AAOA using modern surgical fixation techniques.

METHODS

Retrospective analysis of all patients following C1-C2 arthrodesis with recalcitrant AAOA from a single center, single surgeon from 2002 to 2012. Preoperative, immediate and final follow-up postoperative radiographic images were evaluated. Patient-reported outcomes scores were assessed preoperative, 1-year, and final postoperative follow-up.

RESULTS

We found a total of 14 patients (13 female, 1 male) with average follow-up of 2.96 ± 2.26 years and mean age at surgery of 71.8 ± 9.3 years old. The most common construct was posterior C1-C2 bilateral screw-rod construct (SRC) (n = 9), and there were 3 patients with transarticular screw (TAS) constructs, and 2 patients with hybrid fixation (unilateral SRC and contralateral TAS). Mean change from baseline to final follow-up for Numeric Pain Rating Scale (NRS) was -4.7 ± 2.1, and Neck Disability Index (NDI) was -21.0 ± 13.6, with 11 (78.6%) patients demonstrated a substantial clinical benefit (change in NDI ≥ 10). There were no differences from baseline to all follow-up time points for SF-12 Physical and Mental Component Scores. All patients had evidence of solid C1-C2 arthrodesis and stable fixation at final follow-up, with no significant change in subaxial sagittal alignment. There were no perioperative or postoperative complications.

CONCLUSION

We report one of the largest series evaluating patient-reported outcomes in patients following arthrodesis for AAOA using modern C1-C2 fixation techniques. Our study found C1-C2 arthrodesis for AAOA to be safe and effective, with a significant improvement in patient-reported pain and neck disability and most patients reporting substantial clinical benefit.

LEVEL OF EVIDENCE

4.

C1-C2 posterior fixation: are 4 screws better than 2?

BACKGROUND

Several types of C1-C2 fixation techniques have been described over the years in order to treat atlantoaxial instability.

OBJECTIVE

To compare the pros and cons of the most popular C1-C2 posterior fixation used today: C1 lateral mass-C2 pedicle screw and rods (Harms) and transarticular screw (Magerl) fixations.

METHODS

Retrospective review of 122 patients who underwent Harms or Magerl fixation for atlantoaxial instability. Surgical, clinical, and radiological outcomes were compared in the 2 groups.

RESULTS

123 operations were performed, of which 47 were by the Harms technique (group H) and 76 by the Magerl technique (group M). No significant differences were found in duration of surgery, blood loss, postoperative pain, and length of hospitalization. Postoperatively, neck pain, C2-radiculopathy, and hand function improved in both groups, with better, but not statistically significant, results for group H. The intraoperative complication rate was 2.1% in group H and 21% in group M (P < .05); postoperative complication rate was 10.6% in group H and 21% in group M (P > .05). The major complications were vertebral artery injury (2.1% in group H, 13.1% in group M, P = .05) and screw fracture (2.1% in group H, 9.2% in group M, P > .05). Fusion rate at the end of follow-up was not significantly higher in group H. C1-C2 range of movements in flexion/extension at the end of follow-up was lower in group H (P = .017).

CONCLUSION

Magerl with posterior wiring and Harms techniques are both effective options for stabilizing the atlantoaxial complex. However, the Harms technique appears to be safer, to have fewer complications, and to demonstrate a more robust long-term fixation.

Outcomes of fusion for lateral atlantoaxial osteoarthritis: meta-analysis and review of literature

OBJECTIVE

Atlantoaxial osteoarthritis (AAOA) is an underrecognized source of neck pain, limitation of range of motion, and cervicogenic headaches. When conservative treatments such as facet injections fail, fusion may be indicated. We reviewed published series describing posterior fusions for atlantoaxial osteoarthritis of the facet joints.

METHODS

Online databases were searched for English-language articles describing the diagnosis and treatment of AAOA. Twenty-three studies reporting on 246 patients treated with posterior fusion for lateral AAOA fulfilled inclusion criteria. Standard statistical and formal meta-analytic techniques were used to assess outcomes.

RESULTS

All studies provided class III evidence. The 30-day perioperative mortality was 1.2% and neurologic injury did not occur. Patients were followed for a mean of nearly 5 years. Fusion was successful in 98% of patients with a single operation and with 99.5% of patients after revision surgery. Intractable preoperative neck pain either resolved completely or improved in 97.7% of patients. Using meta-analytic techniques, the point estimate for improvement or resolution of pain was 92.6% (confidence interval = 86.8%-96.0%) and the rate of arthrodesis for AAOA was 92.2% (confidence interval = 85.6%-95.9%) and there were no differences among the various techniques used for fusion. Operative complications were few.

CONCLUSIONS

Posterior C1-2 fusion is a safe and effective treatment option for patients with intractable neck pain secondary to lateral AAOA. Modern fusion options offer a high rate of arthrodesis and low risk of morbidity if conservative therapies fail to provide adequate pain relief.

Is external cervical orthotic bracing necessary after posterior atlantoaxial fusion with modern instrumentation: meta-analysis and review of literature

BACKGROUND

No guidelines exist regarding external cervical orthoses (ECO) after atlantoaxial fusion. We reviewed published series describing C1-2 posterior instrumented fusions with screw-rod constructs (SRC) or transarticular screws (TAS) and compared rates of fusion with and without postoperative ECO.

METHODS

Online databases were searched for English-language articles between 1986 and April 2011 describing ECO use after posterior atlantoaxial instrumentation with SRC or TAS. Eighteen studies describing 947 patients who had SRC (± ECO: 254 of 693 patients), and 33 studies describing 1424 patients with TAS (± ECO: 525 of 899 patients) met inclusion criteria. Meta-analysis techniques were applied to estimate rates of fusion with and without ECO use.

RESULTS

All studies provided class III evidence, and no studies directly compared outcomes with or without ECO use. There was no significant difference in the proportion of patients who achieved successful fusion between patients treated with ECO and without ECO for SRC or TAS patients. Point estimates and 95% confidence intervals (CI) for rates of fusion ± ECO were 97.4% (CI: 95.2% to 98.6%) versus 97.9% (CI: 93.6% to 99.3%) for SRC and 93.6% (CI: 90.7% to 95.6%) versus 95.3% (CI: 90.8% to 97.7%) for TAS. There was no correlation between duration of ECO treatment and fusion (dose effect).

CONCLUSIONS

After C1-2 fusion with modern instrumentation, ECO may be unnecessary (class III). Some centers recommend ECO use with patients with softer bone quality (class IV). Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary to determine the utility of ECO after C1-2 fusion and its impact on patient comfort and cost.

Atlantoaxial fusion with transarticular screws: meta-analysis and review of the literature

OBJECTIVE

To review published series describing C1-2 posterior instrumented fusions and summarize clinical and radiographic outcomes of patients treated with transarticular screw (TAS) fixation.

METHODS

Online databases were searched for English-language articles published between 1986 and April 2011 describing posterior atlantoaxial instrumentation with C1-2 TAS fixation. There were 45 studies including 2073 patients treated with TAS that fulfilled inclusion criteria. Meta-analysis techniques were used to calculate outcomes.

RESULTS

All studies provided class III evidence. The 30-day perioperative mortality rate was 0.8%, and the incidence of neurologic injury was 0.2%. The incidence of clinically significant malpositioned screws was 7.1% (confidence interval [CI], 5.7%-8.8%), the incidence of vertebral artery injury was 3.1% (CI, 2.3%-4.3%), and the rate of fusion with the TAS technique was 94.6% (CI, 92.6%-96.1%).

CONCLUSIONS

TAS fixation is a safe and effective treatment option for C1-2 instability with high rates of fusion (approximately 95%). Screw malposition and vertebral artery injury occurred in approximately 5% of patients. The successful insertion of TAS requires a thorough knowledge of atlantoaxial anatomy.

Accuracy and complications associated with posterior C1 screw fixation techniques: a radiographic and clinical assessment

BACKGROUND CONTEXT

The variable C1 anatomy can make instrumentation challenging and prone to potentially severe complications. New techniques have expanded available options.

PURPOSE

The aims of this study were to evaluate a large series of posterior C1 screws to determine accuracy by computed tomography (CT) scan; assess dimensions of "safe bony windows" with CT; and assess perioperative complication rate related to errant screw placement.

STUDY DESIGN

Retrospective review of a single tertiary care spine database to identify patients with C1 instrumentation between December 2002 and September 2008.

PATIENT SAMPLE

The sample comprised 176 patients with 344 C1 screws. All 176 patients were assessed for perioperative complications related to their C1 screws. Twenty-nine patients did not have postoperative CT scans, leaving 147 patients with 286 screws for analysis of screw accuracy.

OUTCOME MEASURES

The outcome measures consisted of a radiographic assessment of accuracy of placement of C1 instrumentation and a clinical assessment of perioperative complications related to C1 instrumentation focusing on neurologic and vascular injuries.

METHODS

Clinical data were obtained from the medical record. Radiographic analyses included preoperative and postoperative CT scans to quantify the patients' bone and classify accuracy of instrumentation. Screws were graded using the following definitions: Type I, screw threads completely within the bone; Type II, less than half the diameter of the screw violates the surrounding cortex; and Type III, clear violation of transverse foramen or spinal canal.

RESULTS

One hundred seventy-six patients (97 males and 79 females) underwent posterior C1 screw (lateral mass [LM] or transarticular [TA]) fixation. A total of 344 screws were placed with 216 LM screws and 128 TA screws. Twenty-nine patients (58 screws) did not have postoperative CT scans and were not included for analysis of radiographic accuracy but were included in assessment of complications based on medical records. Ninety-six percent of screws (Type I or II) were rated as "safe," and 86% of screws were rated as being ideal (Type I). Twelve screws (4%) were unacceptably placed (Type III). There were no known neurologic or vertebral artery injuries. One patient underwent revision surgery for a medially placed screw. Mean C1 LM width was 10.5 mm across all patients. Estimated blood loss averaged 331 mL.

CONCLUSIONS

Our findings demonstrate a low incidence of complications associated with posterior screw instrumentation of the C1 LM.

The options of C2 fixation for os odontoideum: a radiographic study for the C2 pedicle and lamina anatomy

INTRODUCTION

Patients with os odontoideum always present instability in atlantoaxial joint and need atlantoaxial fixation. C2 pedicle or laminar screws fixation has proven to be efficient and reliable for atlantoaxial instability. However, os odontoideum is a congenital or developmental disease, featured with anomalous bony anatomies. The anatomic measurements and guidelines for C2 pedicle screw placement in general population tends to differ with those of os odontoideum patients, for whom C2 pedicle screws are often needed. The option and techniques of C2 fixation are still challenging and yet to be fully explored.

MATERIAL AND METHODS

We recruited 29 adult patients with os odontoideum and measured the dimension of C2 pedicle and lamina for each patient to examine how well do they match with the screws anatomically. In order to access the intra-observer reliability and inter-observer repeatability of the measurements, the intraclass correlation coefficient (ICC) was also calculated.

RESULTS

The results for reliability of the CT measurements showed excellent intraobserver (ICC = 0.95 and 0.96) and interobserver correlation coefficient (ICC = 0.93). The diameter and length of C2 pedicle were found to be 6.06 ± 1.37 and 24.05 ± 2.54 mm, while the corresponding figures of C2 laminar were 6.95 ± 0.82 and 25.60 ± 2.18 mm, respectively. In the measurements, all 29 cases had suitable diameter (larger than 5.5 mm) for C2 laminar screw (the laminar diameters ranged from 5.52 to 8.82 mm). In C2 pedicle measurements, the diameters of the 29 cases were from 3.50 to 9.86 mm, while 20 pedicles (34.5%) in 14 cases were less than 5.5 mm in diameter. Six had bilateral small pedicles where the diameter was less than 5.5 mm.

CONCLUSION

Anatomically, we found laminar screw is a better match in comparison with pedicle screw for C2 fixation in os odontoideum. The options for C2 fixation should be made based on careful preoperative imaging and thorough consideration. Preoperative reconstructive CT scan can offer great assistance for the choice of fixation in os odontoideum by revealing the anatomy of the C2 pedicles in detail.

Upper cervical manipulation combined with mobilization for the treatment of atlantoaxial osteoarthritis: a report of 10 cases

OBJECTIVE

This study presents the outcomes of patients with idiopathic degenerative and posttraumatic atlantoaxial osteoarthritis who were treated with upper cervical manipulation in combination with mobilization device therapy.

CLINICAL FEATURES

A retrospective case review of 10 patients who were diagnosed with either degenerative or posttraumatic atlantoaxial arthritis based on histories, clinical symptoms, physical examination, and radiographic presentations was conducted at a multidisciplinary integrated clinic that used both chiropractic and orthopedic services. All 10 patients selected for this series were treated with a combination of upper cervical manipulation and mechanical mobilization device therapy. Outcome measures were collected at baseline and at the end of the treatment period. Assessments were measured using patients' self-report of pain using a numeric pain scale (NPS), physical examination, and radiologic changes. Average premanipulative NPS was 8.6 (range, 7-10), which was improved to a mean NPS of 2.6 (range, 0-7) at posttreatment follow-up. Mean rotation of C1-C2 at the end of treatment was improved from 28° (±3.1) to 52° (±4.5). Restoration of joint space was observed in 6 patients. Overall clinical improvement was described as "good" or "excellent" in about 80% of patients. Clinical improvements in pain and range of motion were seen in 80% and 90% of patients, respectively.

CONCLUSION

Chiropractic management of atlantoaxial osteoarthritis yielded favorable outcomes for these 10 patients.

Transarticular screw fixation of C1-2 for the treatment of arthropathy-associated occipital neuralgia

Two patients with occipital neuralgia due to severe arthropathy of the C1-2 facet joint were treated using atlantoaxial fusion with transarticular screws without decompression of the C-2 nerve root. Both patients experienced immediate postoperative relief of occipital neuralgia. The resultant motion elimination at C1-2 eradicated not only the movement-evoked pain, but also the paroxysms of true occipital neuralgia occurring at rest. A possible pathophysiological explanation for this improvement is presented in the context of the ignition theory of neuralgic pain. This represents the first report of C1-2 transarticular screw fixation for the treatment of arthropathy-associated occipital neuralgia.

Placement of occipital condyle screws for occipitocervical fixation in a pediatric patient with occipitocervical instability after decompression for Chiari malformation

In cadaveric studies and recently in one adult patient the occipital condyle has been studied as an option to allow bone purchase by fixation devices. In the current case the authors describe the use of occipital condyle screws in a child undergoing occipitocervical fixation. To the best of the authors' knowledge this case is the first reported instance of this technique in a pediatric patient. This girl had a history of posterior fossa decompression for Chiari malformation Type I when she was 22 months of age. When she was 6 years old she presented with neck pain on flexion and extension of her head. Magnetic resonance imaging in flexion and extension revealed occipitocervical instability. She underwent an occiput to C-2 posterior arthrodesis with bilateral screw placement in the occipital condyles, C-2 lamina, and C-1 lateral masses. Postoperatively, she was neurologically intact. Computed tomography demonstrated a stable construct, and her cervical pain had resolved on follow-up.

Preoperative radiographic factors and surgeon experience are associated with cortical breach of C2 pedicle screws

STUDY DESIGN

A retrospective review study.

OBJECTIVE

In this study, we attempt to identify radiographic variables associated with likelihood of intraoperative breach during C2 pedicle screw placement. In addition, we attempt to correlate surgeon experience with breach rate.

SUMMARY OF BACKGROUND DATA

Pedicle screws have emerged as an effective approach for obtaining fixation of the axis, yet placement of C2 pedicle screws is technically demanding and poses the risk of injury to the vertebral artery. Given the evidence for substantial variation in C2 anatomy, preoperative assessment of computed tomography (CT) scans may indicate, which patients are at increased risk for cortical breach during the pedicle screw placement.

MATERIALS AND METHODS

A retrospective review of all patients undergoing C2 pedicle screw fixation at a single institution over the last 6 years was conducted. Radiographic cortical breaches were defined on postoperative CT scans as visualization of the screw beyond the cortical edge. Radiographic measurements were determined from preoperative CT scans and were then correlated with breaches via Student t test. The association of breach rate with surgeon experience was evaluated using univariate linear regression.

RESULTS

Ninety-three patients underwent placement of 170 screws. Cortical breach was detected on postoperative CT scans in 43 screws (25.3%). One clinically significant breach occurred with damage to the left vertebral artery intraoperatively. On axial CT sections, mean pedicle isthmus diameter was significantly smaller in patients with breach than in patients without breach for both left and right sides, P=0.006 and P=0.010, respectively. Specifically, a diameter of less than 6 mm was associated with a nearly 2-fold increase in risk of cortical breach (37% vs. 21%). Surgeons with greater experience in placing C2 pedicle screws were noted to have a lower breach incidence (P=0.004).

CONCLUSIONS

During placement of C2 pedicle screws, likelihood of cortical breach may be associated with size of pedicle and surgeon experience. Extensive preoperative evaluation of CT scans and consideration of technical demands of procedure may help avoid complications with such internal fixation.

Assessment of two measurement techniques of cervical spine and C1-C2 rotation in the outcome research of axis fractures: a morphometrical analysis using dynamic computed tomography scanning

STUDY DESIGN

In vivo study on cervical spine motion.

OBJECTIVE

To estimate the accuracy of clinical measurements, using a handheld goniometer for the assessment of total cervical neck rotation in outcome research of patients with C2 fractures and particularly odontoid fractures. Investigation on whether functional computed tomography (CT)-scanning is decisive in the investigation of functional outcome after C2 fractures.

SUMMARY OF BACKGROUND DATA

Pertinent literature exists concerning indications, techniques, complications of treatment, and risk factors for nonunion in C2 fractures; however, there are scarce data regarding the functional outcome in C2 fractures. Only a few studies assess functional outcome in terms of clinical outcome vehicles and clinical investigation of axial neck rotation, using a handheld goniometer. Measurements of axial neck rotation using a handheld goniometer are assumed not sufficient to compare the results of treatment strategies for C2-fractures or elucidate the ability for posttreatment rotation of C1-C2.

METHODS

The authors selected a homogenous group of 35 patients treated for C2 fractures using nonsurgical and surgical techniques. 69% of patients had odontoid fractures. Mean age of patients was 52 years. Patients were subjected to clinical assessment of axial cervical range of motion for rotation, using a handheld goniometer. Patients were also subjected to functional CT-scanning and measurements of total neck and atlantoaxial rotation were performed according to an established protocol.

RESULTS

With clinical measurements mean range of motion for left and right axial neck rotation was both 56 degrees. According to the functional CT scans, the mean left-sided and right-sided axial neck rotation was 48.6 degrees and 52.0 degrees. The mean for left- and right-sided atlantoaxial rotation was 20.2 degrees and 20.6 degrees. Total axial atlantoaxial rotation on CT scans was 40.3 degrees and total axial neck rotation was 103.3 degrees. In comparison to age and gender matched normal individuals total cervical neck rotation was reduced to a mean of 69.5%. The differences between total axial neck rotation assessed using a handheld goniometer and with functional CT-scanning were strongly significant (P < 0.0001). In addition, there was no statistically significant correlation between the clinically assessed total neck rotation to either the left or the right side and the ipsilateral percentage atlantoaxial rotation of total head neck rotation.

CONCLUSION

The current study demonstrated that for the comparison of functional outcome after different therapies of C2 fractures clinical measurements do not serve for reliable data on total neck rotation and particularly atlantoaxial rotation and the percentage of C1-C2 rotation of total neck rotation. The use of dynamic CT-scans in the analysis of functional outcome after C2 fractures is strongly recommended.

C2-fractures: part II. A morphometrical analysis of computerized atlantoaxial motion, anatomical alignment and related clinical outcomes

Knowledge on the outcome of C2-fractures is founded on heterogenous samples with cross-sectional outcome assessment focusing on union rates, complications and technical concerns related to surgical treatment. Reproducible clinical and functional outcome assessments are scant. Validated generic and disease specific outcome measures were rarely applied. Therefore, the aim of the current study is to investigate the radiographic, functional and clinical outcome of a patient sample with C2-fractures. Out of a consecutive series of 121 patients with C2 fractures, 44 met strict inclusion criteria and 35 patients with C2-fractures treated either nonsurgically or surgically with motion-preserving techniques were surveyed. Outcome analysis included validated measures (SF-36, NPDI, CSOQ), and a functional CT-scanning protocol for the evaluation of C1-2 rotation and alignment. Mean follow-up was 64 months and mean age of patients was 52 years. Classification of C2-fractures at injury was performed using a detailed morphological description: 24 patients had odontoid fractures type II or III, 18 patients had fracture patterns involving the vertebral body and 11 included a dislocated or a burst lateral mass fracture. Thirty-one percent of patients were treated with a halo, 34% with a Philadelphia collar and 34% had anterior odontoid screw fixation. At follow-up mean atlantoaxial rotation in left and right head position was 20.2 degrees and 20.6 degrees, respectively. According to the classification system of posttreatment C2-alignment established by our group in part I of the C2-fracture study project, mean malunion score was 2.8 points. In 49% of patients the fractures healed in anatomical shape or with mild malalignment. In 51% fractures healed with moderate or severe malalignment. Self-rated outcome was excellent or good in 65% of patients and moderate or poor in 35%. The raw data of varying nuances allow for comparison in future benchmark studies and metaanalysis. Detailed investigation of C2-fracture morphology, posttreatment C2-alignment and atlantoaxial rotation allowed a unique outcome analysis that focused on the identification of risk factors for poor outcome and the interdependencies of outcome variables that should be addressed in studies on C2-fractures. We recognized that reduced rotation of C1-2 per se was not a concern for the patients. However, patients with worse clinical outcomes had reduced total neck rotation and rotation C1-2. In turn, C2-fractures, especially fractures affecting the lateral mass that healed with atlantoaxial deformity and malunion, had higher incidence of atlantoaxial degeneration and osteoarthritis. Patients with increased severity of C2-malunion and new onset atlantoaxial arthritis had worse clinical outcomes and significantly reduced rotation C1-2. The current study offers detailed insight into the radiographical, functional and clinical outcome of C2-fractures. It significantly adds to the understanding of C2-fractures.

C2-fractures: part I. Quantitative morphology of the C2 vertebra is a prerequisite for the radiographic assessment of posttraumatic C2-alignment and the investigation of clinical outcomes

Pertinent literature exists concerning indications, techniques, complications of treatment, and risk factors for nonunion in axis and odontoid fractures; however, there are scarce data regarding the incidence and definition of malunion in these fractures. As a prerequisite for the study of anatomical alignment following surgical and nonsurgical treatment of C2-fractures, an understanding of normal C2 anatomy is essential. Therefore, the authors intended to evaluate morphometrical dimensions of the C2 vertebra. The purpose was to provide normalized quantitative data to enable assessment of malalignment following the treatment of C2-fractures within a classification system. Using digitized cervical spine lateral and transoral odontoid radiographs of 100 consecutive patients without any evidence of traumatic or neoplastic disorders, the authors performed measurements on distinct anatomical structures and investigated morphometrical dimensions of the normal axis vertebra. The incidence of atlantoaxial arthritis was also evaluated. In addition, with the assessment of twenty arbitrarily chosen sets of radiographs by three different observers we calculated the interobserver reliability in terms of intraclass correlation coefficients for each parameter. With calculation of SD and 95% confidence limits, pathological cut-offs were reconstructed from measurements performed resembling non-physiological and pathological limits. Distinct parameters were selected to form a new classification system for radiographical follow-up that focuses on the quantitative C1-2 vertebral alignment. The measurement process resulted in 2,400 data points. Distinct morphometrical parameters, such as a quantitative characterization of the sagittal atlantoaxial congruency, the lateral mass inclination and the type of degenerative changes at the atlantoaxial joint could be demonstrated to be valuable and reliably used within a proposed classification for C2-malunions following C2-fractures. The current study offers a template including recommended radiological measurements for further research on the study of clinical outcome and posttraumatic alignment following C2-fractures.

Radiographic and clinical evaluation of free-hand placement of C-2 pedicle screws

Object

Stabilization of the cervical spine can be challenging when instrumentation involves the axis. Fixation with C1–2 transarticular screws combined with posterior wiring and bone graft placement has yielded excellent fusion rates, but the technique is technically demanding and places the vertebral arteries (VAs) at risk. Placement of screws in the pars interarticularis of C-2 as described by Harms and Melcher has allowed rigid fixation with greater ease and theoretically decreases the risk to the VA. However, fluoroscopy is suggested to avoid penetration laterally, medially, and superiorly to avoid damage to the VA, spinal cord, and C1–2 joint, respectively. The authors describe how, after meticulous dissection of the C-2 pars interarticularis, such screws can be placed accurately and safely without the use of fluoroscopy.

Methods

Prospective follow-up was performed in 55 consecutive patients who underwent instrumented fusion of C-2 by a single surgeon. The causes of spinal instability and type and extent of instrumentation were documented. All patients underwent preoperative CT or MR imaging scans to determine the suitability of C-2 screw placement. Intraoperatively, screws were placed following dissection of the posterior pars interarticularis. Postoperative CT scans were performed to determine the extent of cortical breach. Patients underwent clinical follow-up, and complications were recorded as vascular or neurological. A CT-based grading system was created to characterize such breaches objectively by location and magnitude via percentage of screw diameter beyond the cortical edge (0 = none; I = < 25% of screw diameter; II = 26–50%; III = 51–75%; IV = 76–100%).

Results

One-hundred consecutive screws were placed in the pedicle of the axis by a single surgeon using external landmarks only. In 10 cases, only 1 screw was placed because of a preexisting VA anatomy or bone abnormality noted preoperatively. In no case was screw placement aborted because of complications noted during drilling. Early complications occurred in 2 patients and were limited to 1 wound infection and 1 transient C-2 radiculopathy. There were 15 total breaches (15%), 2 of which occurred in the same patient. Twelve breaches were lateral (80%), and 3 were superior (20%). There were no medial breaches. The magnitude of the breach was classified as I in 10 cases (66.7% of breaches), II in 3 cases (20% of breaches), III in 1 case (6.7%), and IV in 1 case (6.7%).

Conclusions

Free-hand placement of screws in the C-2 pedicle can be done safely and effectively without the use of intraoperative fluoroscopy or navigation when the pars interarticularis/pedicle is assessed preoperatively with CT or MR imaging and found to be suitable for screw placement. When breaches do occur, they are overwhelmingly lateral in location, breach < 50% of the screw diameter, and in the authors' experience, are not clinically significant.

The Neck Pain and Disability Scale: cross-cultural adaptation into German and evaluation of its psychometric properties in chronic neck pain and C1-2 fusion patients

STUDY DESIGN

Cross-cultural adaptation of an outcome questionnaire.

OBJECTIVE

The aim of the study was to cross-culturally adapt the Neck Pain and Disability Scale (NPAD) for the German language, and to assess its psychometric qualities.

SUMMARY OF BACKGROUND DATA

Neck pain and its associated disability represent an extremely common musculoskeletal problem. Reliable and valid questionnaires for its assessment are available in English, but no German versions of these exist.

METHODS

The English version of the NPAD was translated into German (NPAD-D) and back-translated according to established guidelines. Twenty-three patients with chronic neck pain completed the NPAD-D twice over 1 to 2 weeks, to assess its test-retest reliability. A further 80 patients [40% male, mean (SD) 54 (18) years] completed the questionnaire and underwent a clinical follow-up examination, 1 to 14 years after C1-C2 fusion. These patients also documented their satisfaction with the surgery.

RESULTS

Cronbach's alpha values (internal consistency) for the NPAD-D whole scale and for the NPAD-D subscales pain, disability, and neck-specific function were 0.97, 0.95, 0.97, and 0.87, respectively. The ICC for the test-retest reliability of the NPAD-D was excellent (0.97) and the SEM was relatively low (3.8), giving a "minimal detectable difference" for the scale of 10.5 (scale range is 0-100). The range of motion in rotation, assessed during the clinical examination, correlated significantly with the scores on NPAD-D item 16 (stiffness of neck) (Rho = -0.52, P < 0.0001) and item 17 (trouble turning neck) (Rho = -0.59, P < 0.0001). Range of motion in flexion-extension correlated significantly with the scores on item 18 (trouble looking up and down) (Rho = -0.60, P < 0.0001) and item 19 (trouble working overhead) (Rho = -0.45, P < 0.0001). The NPAD-D scores differed significantly between patients who were satisfied with the result of their operation and those who were not [mean values 36.4 (SD 24.3) and 58.1 (SD 27.4), respectively; P = 0.008].

CONCLUSION

The NPAD-D is a reliable and valid patient-orientated instrument for use in future studies of neck pain and disability in German speaking patients.

Laminar screw fixation of the axis

Object

Laminar fixation of the axis with crossing bilateral screws has been shown to provide rigid fixation with a theoretically decreased risk of vertebral artery damage compared with C1–2 transarticular screw fixation and C-2 pedicle screw fixation. Some studies, however, have shown restricted rigidity of such screws compared with C-2 pedicle screws, and others note that anatomical variability exists within the posterior elements of the axis that may have an impact on successful placement. To elucidate the clinical impact of such screws, the authors report their experience in placing C-2 laminar screws in adult patients over a 2-year period, with emphasis on clinical outcome and technical placement.

Methods

Sixteen adult patients with cervical instability underwent posterior cervical and cervicothoracic fusion procedures at our institution with constructs involving C-2 laminar screws. Eleven patients were men and 5 were women, and they ranged in age from 28 to 84 years (mean 57 years). The reasons for fusion were degenerative disease (9 patients) and treatment of trauma (7 patients). In 14 patients (87.5%) standard translaminar screws were placed, and in 2 (12.5%) an ipsilateral trajectory was used. All patients underwent preoperative radiological evaluation of the cervical spine, including computed tomography scanning with multiplanar reconstruction to assess the posterior anatomy of C-2. Anatomical restrictions for placement of standard translaminar screws included a deeply furrowed spinous process and/or an underdeveloped midline posterior ring of the axis. In these cases, screws were placed into the corresponding lamina from the ipsilateral side, allowing bilateral screws to be oriented in a more parallel, as opposed to perpendicular, plane. All patients were followed for > 2 years to record rates of fusion, instrumentation failure, and other complications.

Results

Thirty-two screws were placed without neurological or vascular complications. The mean follow-up duration was 27.3 months. Complications included 2 revisions, one for pseudarthrosis and the other for screw pullout, and 3 postoperative infections.

Conclusions

Placement of laminar screws into the axis from the standard crossing approach or via an ipsilateral trajectory may allow a safe, effective, and durable means of including the axis in posterior cervical and cervicothoracic fusion procedures.

The lasso technique for posterior C1-C2 fusion

OBJECTIVE

Posterior atlantoaxial arthrodesis requires placement of a bone graft in a properly prepared environment that includes decorticated bony surfaces, compressive forces between graft and native bone, and limited motion. To achieve posterior atlantoaxial arthrodesis, various cable-and-graft constructs have been used, all of which require an intact posterior arch of C1. For patients who lack an intact arch owing to congenital, iatrogenic, or traumatic causes, we have devised the "lasso technique," which uses the remnants of the posterior arch of C1 for placement of the graft to achieve fusion isolated to C1-C2 or to be part of an occipitocervical construct.

METHODS

A retrospective record review was conducted of all patients who underwent the lasso technique. Clinical and radiographic history, perioperative course, and time to fusion were recorded. We describe the technique in detail.

RESULTS

During the last 13 years, we have used this technique successfully in five female and four male patients. The absent or incompetent posterior arch was a congenital defect in one patient, a result of prior surgical removal in four patients, and caused by fracture associated with prior failed fusion attempts in four other patients. All patients experienced successful fusion after an average of 6.8 months.

CONCLUSION

Securing a bone graft in the absence of an intact C1 lamina is a challenge when a patient presents with atlantoaxial instability. We have devised the lasso technique to secure an interpositional C1-C2 graft using the remnants of the posterior atlantal arch. Although this technique has been required relatively infrequently, we have found it to be valuable and effective in our practice.

The use of C1 lateral mass screws in complex cervical spine surgery: indications, techniques, and outcome in a prospective consecutive series of 25 cases

OBJECTIVES

Direct C1 lateral mass/C2 pars or pedicle screw fixation has been recently proposed as an alternative method to C1-C2 transarticular screw fixation. Although this method seems attractive, there are currently limited clinical data on the use of this technique for multilevel fixation including complex craniocervical reconstructions. The objectives of this study were to assess the safety and the clinical/radiographic outcomes in patients undergoing cervical spine surgery using C1 lateral mass screws (C1-LMS).

METHODS

A prospectively accrued database was reviewed to determine initial presentation, etiology, operations, complications, and clinical/radiologic outcomes.

RESULTS

Twenty-five patients with a mean age of 56 underwent fixation with C1-LMS. Mean follow-up was 12 months. The indications for using C1-LMS instead of C1-C2 transarticular screws were: unfavorable bony or vascular anatomy, tumor destruction, thoracic kyphosis or cervical hyperlordosis, inability to reduce the C1-C2 dislocation intraoperatively and or surgeon preference. Satisfactory stability was achieved in all cases with no neurologic or vascular complications. In one case, the C1 screws breached the medial cortex. Three patients developed transient postoperative C2 neuralgia. One patient had an extended stay in ICU due to respiratory issues.

CONCLUSIONS

On the basis of our experience, proficiency with the use of C1-LMS screw fixation greatly enhances the ability to manage complex atlantoaxial or craniocervical pathologies with low morbidity. This technique should be considered an excellent adjunct or alternative to transarticular screw fixation.