We evaluated the trajectory and the entry points of anterior transpedicular screws (ATPS) in the cervicothoracic junction (CTJ).
Objective
This study aimed at investigating the feasibility of ATPS fixation in the CTJ.
Summary of background data
Application of an ATPS in the lower cervical spine has been reported; however, there were no reports exploring the feasibility of anterior transpedicular screw fixation in the CTJ.
Methods
CT scans were performed in 50 cases and multiplanar reformation was used to measure the related parameters on pedicle axis view at C6–T2. Transverse pedicle angle, outer pedicle width, pedicle axis length, distance transverse intersection point (DtIP), sagittal pedicle angle, anterior vertebral body height, outer pedicle height, and distance sagittal intersection point (DsIP) were measured. The prozone of CTJ was divided into three different regions, which were named as the “manubrium region”, the region “above” and “below” the manubrium. The distribution of the trajectory of sagittal pedicle axes was recorded in the three regions and the related data were statistically analyzed.
Results
There was no statistical difference in gender (P > 0.05). The transverse pedicle angle decreased from C6 (46.77° ± 2.72°) to T2 (20.62° ± 5.04°). DtIP increased from C6 to T2. DsIP was an average of 7.17 mm. The sagittal pedicle axis lines of the C6 and C7 were located in the region above the manubrium. T1 was mainly in the manubrium region followed by the region above the manubrium. T2 was mainly located in the manubrium region followed by the region below the manubrium.
Conclusion
Implantation of ATPS at C6, C7, and some T1 is feasible through the low anterior cervical approach, while it is almost impossible to approach T2 that way.
To assess the pedicle morphology in the lower thoracic and lumbar spine in an Indian population and to determine the causes of pedicle wall violation by pedicle screws.
Methods
Computerised tomographic scans of 135 consecutive patients with thoracolumbar and lumbar spine fractures were prospectively analysed to determine the pedicle morphology. The transverse pedicle angle, pedicle diameter and screw path length at 527 uninjured levels were measured. Post-operative CT scans of 117 patients were analysed to determine the accuracy of 468 pedicle screws at 234 vertebrae.
Results
The lowest (mean ± SD) transverse pedicle width in the lower thoracic spine was 5.4 ± 0.70 mm, whereas in the lumbar spine it was 7.2 ± 0.87 mm. The shortest (mean ± SD) screw path length in lower thoracic pedicles was 35.8 ± 2.10 and 41.9 ± 2.18 mm in the lumbar spine. The mean transverse pedicle angle in the lower thoracic spine was consistently less than 5°, whereas it gradually increased from L1 through L5 from 8.5° to 30°. Forty-one screws violated the pedicle wall, due to erroneous angle of screw insertion.
Conclusions
In the current study, pedicle dimensions were smaller compared to the Western population. In Indian patients, pedicle screws of 5 mm diameter and 30 mm length, and 6 mm diameter and 35 mm length can safely be used in the lower thoracic and lumbar spine, respectively. However, it is important to assess the pedicle morphology on imaging prior to pedicle fixation.
We report a single-center, prospective, randomized study for pedicle screw insertion in opened and percutaneous spine surgeries, using a computer-assisted surgery (CAS) technique with three-dimensional (3D) intra-operative images intensifier (without planification on pre-operative CT scan) vs conventional surgical procedure.
Material and method
We included 143 patients: Group C (conventional, 72 patients) and Group N (3D Fluoronavigation, 71 patients). We measured the pedicle screw running time, and surgeon’s radiation exposure. All pedicle runs were assessed according to Heary by two independent radiologists on a post-operative CT scan.
Results
3D Fluoronavigation appeared less accurate in percutaneous procedures (24 % of misplaced pedicle screws vs 5 % in Group C) (p = 0.007), but more accurate in opened surgeries (5 % of misplaced pedicle screws vs 17 % in Group C) (p = 0.025). For one vertebra, the average surgical running time reached 8 min in Group C vs 21 min in Group N for percutaneous surgeries (p = 3.42 × 10?9), 7.33 min in Group C vs 16.33 min in Group N (p = 2.88 × 10?7) for opened surgeries. The 3D navigation device delivered less radiation in percutaneous procedures [0.6 vs 1.62 mSv in Group C (p = 2.45 × 10?9)]. For opened surgeries, it was twice higher in Group N with 0.21 vs 0.1 mSv in Group C (p = 0.022).
Conclusion
The rate of misplaced pedicle screws with conventional techniques was nearly the same as most papers and a little bit higher with CAS. Surgical running time and radiation exposure were consistent with many studies. Our work hypothesis is partially confirmed, depending on the type of surgery (opened or closed procedure).
We aimed to study generational changes in the dimensions of cervical and lumbar bony spinal canals in Western Switzerland.
Methods
A total of 254 patients were retrospectively included, 144 of whom were born during 1940–1949 and 110 during 1970–1979. Cervical spine CTs were performed as part of the spinal clearance procedure following trauma (n = 135) or while investigating neurological symptoms (CT angiography, n = 119). Three independent observers digitally measured the cross-sectional area (CSA) at pedicle levels from C0 to C7 and the anteroposterior diameter (APD) at C3, C5, and C7. In addition, lumbar spine CSAs and APDs were measured on whole body trauma or abdominal CTs, which were also available for 134 patients.
Results
Mean CSAs at pedicle levels were numerically smaller in the younger patient group in both cervical and lumbar spine, with the difference reaching statistical significance at all lumbar levels (p ≤ 0.024) except L5. Cervical APDs showed no difference between groups. Subgroup analysis revealed that younger CT angiography patients had a significantly smaller CSA at C1 (p = 0.018) and a similar trend at C4 (p = 0.053). There was moderate positive correlation between cervical and lumbar CSAs, taking C4 and L3 as reference (r = 0.509, p < 0.01).
Conclusions
Younger generation patients have smaller bony spinal canals also in the cervical spine even though this difference is less marked than at the lumbar level. There is, nevertheless, moderate positive correlation between these two anatomical regions. Perinatal factors that adversely influence spinal growth, such as increased maternal age and smoking, could explain these generational changes, given that body height has increased during the same time period. The lesser difference observed in the cervical spine could be due to later closure of the neurocentral synchondrosis at this level.
The technique of pedicle screw stabilization is finding increasing popularity for use in the cervical spine. Implementing anterior transpedicular screws (ATPS) in cervical spine offers theoretical advantages compared to posterior stabilization. The goal of the current study was the development of a new setting for navigated insertion of ATPS, combining the advantage of reduced invasiveness of an anterior approach with the technical advantages of navigation.
Methods
20 screws were implanted in levels C3 to C6 of four cervical spine models (SAWBONES® Cervical Vertebrae with Anterior Ligament) with the use of 3D fluoroscopy navigation system [Arcadis Orbic 3D, Siemens and VectorVision fluoro 3D trauma software (BrainLAB)]. The accuracy of inserted screws was analyzed according to postoperative CT scans and following the modified Gertzbein and Robbins classification.
Results
20 anterior pedicle screws were placed in four human cervical spine models. Of these, eight screws were placed in C3, two screws in C4, six screws in C5, and four screws in C6. 16 of 20 screws (80 %) reached a grade 1 level of accuracy according to the modified Gertzbein and Robbins Classification. Three screws (15 %) were grade 2, and one screw (5 %) was grade 3. Grade 4 and 5 positions were not evident. Summing grades 1 and 2 together as “good” positions, 95 % of the screws achieved this level. Only a single screw did not fulfill these criteria.
Conclusion
The setting introduced in this study for navigated insertion of ATPS into cervical spine bone models is well implemented and shows excellent results, with an accuracy of 95 % (Gertzbein and Robbins grade 2 or better). Thus, this preliminary study represents a prelude to larger studies with larger case numbers on human specimens.
Correction of rigid cervical deformities often requires osteotomies to realign the spine. Cervical pedicle subtraction osteotomy can be technically challenging due to the presence of cervical nerve roots and usually can only be performed at C7 or T1 due to the presence of vertebral arteries. In contrast, anterior cervical osteotomy can be performed throughout the cervical spine and is a safe and effective method for correction of both sagittal and coronal cervical deformities. We describe the anterior cervical osteotomy technique with a review of the pertinent literature.
Methods
A step-by-step technical guide for anterior cervical osteotomy is provided with a focus on surgical nuances and complication avoidance. Two illustrative cases of fixed sagittal and coronal deformities are included to demonstrate the substantial amount of deformity correction achievable using the anterior cervical osteotomy technique.
Results
Both patients in the illustrative cases had successful clinical and radiographic outcome following deformity correction utilizing the anterior cervical osteotomy technique.
Conclusion
Anterior cervical osteotomy is a safe and effective technique for correction of rigid cervical deformities. Spine surgeons should be familiar with this technique to optimize clinical outcome in patients undergoing cervical deformity correction.
Spinal navigation has made significant advances in the last two decades. After initial experiences with pedicle screws in the thoracic and lumbar spine, technological improvements have resulted in their increased application in the cervical spine. Instrumentation techniques like cervical pedicle screws, lateral mass screws in C1 and transarticular screws C1/C2 have become standard due to the application of image guidance.
Technique
Different navigation techniques can be distinguished based on the type of imaging. In the cervical spine, the preoperative computer tomography (CT) scan that requires intraoperative matching is still the standard of care due to the high image quality. 3D fluoroscopy navigation techniques are currently widely used in the lumbar spine, but the reduced image quality obviates the application in the more sophisticated cervical anatomy or the cervicothoracic region. The future availability of intraoperative CT scans (iCT) combines the advantages of high image quality with those of intraoperative image acquisition. This will lead to a wider use of image guidance in the cervical spine and will enable the surgeon to apply minimally invasive techniques with higher accuracy.
Application
The successful application of spinal navigation is based on the technical knowledge of navigation systems and its exercise in daily routine. Only the sufficient experience of the clinical staff makes it possible to standardize operational procedures to increase patient safety, reduce radiation dose and shorten operation time.
Pedicle screw placement is an increasingly common procedure for the correction of spine degenerative disease, deformity and trauma. However, screw placement is demanding, with complications resulting from inaccurate screw placement. While several different techniques have been developed to improve accuracy, they all have their limitations.
Methods
We examined the MySpine (Medacta International SA, Castel San Pietro, CH) patient-matched pedicle targeting guide in three cadaveric spine specimens operated on by three surgeons. A three-dimensional (3D) preoperative plan was constructed from spinal computed tomography scans, from which individualised guides were developed for the placement of Medacta Unconstrained Screw Technology pedicle screws. Following screw placement, the 3D positioning of the screws was compared to the preoperative plan against a series of pre-defined criteria.
Results
Of 46 inserted screws eligible for assessment, 91.3 % were fully inside the pedicle. There were no cases of Grade B (2–4 mm) or C (>4 mm) pedicle perforation. The mean deviation between the planned and actual screw position at the midpoint of the pedicle was 0.70 mm, the mean horizontal deviation was 0.60 mm and the mean vertical deviation was 0.77 mm. The mean angular deviation in the sagittal plane was 1.74°, versus 1.32° in the transverse plane. The mean deviation in screw depth was 1.55 mm. On all measures, the accuracy of screw placement was within the predefined criteria.
Conclusions
Our cadaver study indicates that pedicle screw placement with the system is accurate and should be investigated in larger in vitro and in vivo studies.
C5 palsy is a well-known complication of cervical spine decompression surgery. The complication develops in both posterior and anterior approaches. We aimed to review reports regarding postoperative C5 palsy in hopes for better prevention and treatment of this morbidity.
Method
We systematically reviewed and evaluated the abstracts and full texts of the identified papers in the literature. We reviewed and analyzed papers published between January 1970 and February 2015 regarding C5 palsy as a complication of cervical surgical procedures. We made statistical comparisons as much as possible.
Results
We did not find any statistical significance between the pathologies (p = 0.088) and between the surgical routes (p = 0.486). There was statistical significance between the types of procedures (p < 0.05). Posterior laminectomy had low incidence of C5 palsy when compared to laminectomy and fusion (p = 0.029) and laminoplasty (p = 0.37). There was no statistically significant difference between anterior cervical decompression and fusion and other procedures (p > 0.05).
Conclusion
Some studies conclude that anterior procedure is more safe. Of all anterior procedures, the multilevel ACDF had the lowest incidence of C5 palsy. The hybrid technique can be chosen for more than two-vertebra corpectomy. In term of posterior procedures, laminectomy is safer. To prevent C5 palsy, electromyography can be used as a sensitive predictor and selective foraminotomy can be performed.
Injuries to the cervical spine are immanently accompanied by trauma to the extracranial cerebral arteries.
Material and methods
A prospective cohort study was carried out from October 2013 to October 2015 including 76 patients (39 women and 37 men) with a median age of 77 years and either fractures or discoligamentary injuries who were examined with duplex sonography and/or computed tomography (CT) angiography. Additionally, approximately 80 patients with a cervical spine distorsion were evaluated using the same modalities. Statistical analyses were carried out using the program Bias 11.01.
Results
The overall incidence of traumatic dissection of the internal carotid artery was 2.5?% and in 50?% of the cases (1.2?%) with neurological symptoms. For vertebral arteries the incidence of 10.5?% was relatively high and 25?% of patients were symptomatic (2.6?%). Osteophytes and the degree of displacement were identified as the major risk factors. The vertebral canal and the skull base were regions most prone to vascular injury. In the case of distorsion of the cervical spine no vascular trauma has so far been found.
Conclusion
In cases of trauma to the cervical spine accompanying vascular injuries should also be taken into consideration. The current therapy option is anticoagulation in cases of neurologically asymptomatic patients. Patients with neurological symptoms could benefit from endovascular techniques.
Patients with severe spinal deformities often have small pedicle diameters, and pedicle dimensions vary between segments and individuals. Free-hand pedicle screw placement can be inaccurate. Individualized drill guide templates may be used, but the accuracy of pedicle screw placement in severe scoliosis remains unknown. The accuracy of drill guide templates and free-hand technique for the treatment of adolescent patients with severe idiopathic scoliosis are compared in this study.
Methods
This study included 37 adolescent patients (mean age 16.4 ± 1.3 years) with severe idiopathic scoliosis treated surgically at a single spine center between January 2014 and June 2017. Spinal deformities were corrected using posterior pedicle screw fixation. Patients in group I were treated with rapid prototype drill guide template technique (20 patients; 396 screws) and patients in group II were treated with free-hand technique (17 patients; 312 screws). Outcomes that included operative time, correction rate, and the incidence and distribution of screw misplacement were evaluated.
Results
Operative time in group I was 283 ± 22.7 min compared to 285 ± 25.8 min in group II (p = 0.89). The scoliosis correction rate was 55.0% in group I and 52.9% in group II (p = 0.33). Based on both axial and sagittal reconstruction images, the accuracy rate of pedicle screw placement was 96.7% in group I and 86.9% in group II (p = 0.000).
Conclusion
The drill guide template technique has potential to offer more accurate and thus safer placement of pedicle screws than free-hand technique in the treatment of severe scoliosis in adolescents.
The Harms technique is now considered as the gold standard to stabilize C1–C2 cervical spine. It has been reported to decrease the risk of vertebral artery injury. However, the risk of vascular injury does not totally disappear, particularly due to the proximity of the trans-isthmic C2 screw with the foramen transversarium of C2. In order to decrease this risk of vertebral artery injury, it has been proposed to use a shorter screw which stops before the foramen transversarium.
Object
The main objective was to compare the pull-out strength of long trans-isthmic screw (LS) versus short isthmic screw (SS) C2 screw. An additional morphological study was also performed.
Method
Thirteen fresh-frozen human cadaveric cervical spines were included in the study. Orientation, width and height of the isthmus of C2 were measured on CT scan. Then, 3.5-mm titanium screws were inserted in C2 isthmus according to the Harms technique. Each specimen received a LS and a SS. The side and the order of placement were determined with a randomization table. Pull-out strengths and stiffness were evaluated with a testing machine, and paired samples were compared using Wilcoxon signed-rank test and also the Kaplan–Meier method.
Results
The mean isthmus transversal orientation was 20° ± 6°. The mean width of C2 isthmus was less than 3.5 mm in 35 % of the cases. The mean pull-out strength for LS was 340 ± 85 versus 213 ± 104 N for SS (p = 0.004). The mean stiffness for the LS was 144 ± 40 and 97 ± 54 N/mm for the SS (p = 0.02).
Discussion
The pull-out strength of trans-isthmic C2 screws was significantly higher (60 % additional pull-out resistance) than SSs. Although associated with an inferior resistance, SSs may be used in case of narrow isthmus which contraindicates 3.5-mm screw insertion but does not represent the first option for C2 instrumentation.
Patient-reported outcomes require validation in a particular language and culture before administration for clinical use.
Materials and methods
A systematic translation of the IKDC Subjective Knee Form was initially tested in 30 patients with various knee pathologies to develop the first Greek version (IKDC/SKF-GR). It was then administered to another 80 patients. The test–retest reliability (n = 35) and internal consistency (n = 80) were examined. Construct validity was tested by correlating the IKDC/SKF-GR with the SF-36 subscales (n = 80) and content validity by measuring floor/ceiling effects. Responsiveness was measured in patients with meniscus pathology (n = 24).
Results
Patients filled the form without omissions/questions regarding the phrasing of items. Internal consistency was good (Cronbach’s α = 0.87) and test–retest reliability very good (ICC2,1 = 0.95, SEM = 4.4 and SDC = 12.2). Correlations with the SF-36 subscales confirmed its construct validity. No floor/ceiling effects were recorded. The effect size was large (ES = 1.26).
Conclusions
The IKDC/SKF-GR has comparable measurement properties to the original form.
Despite proven biomechanical superiority and resultant superior clinical outcomes, pedicle instrumentation in cervical spine is not widely practiced due to technical difficulties, steep learning curve, and possible potential catastrophic complications due to screw misplacement. This study was undertaken with the purpose to evaluate the feasibility, accuracy, and complications of cervical pedicle screw instrumentation solely using O-arm-based 3D navigation technology.
Methods
Prospectively maintained data from a single-surgeon case series were retrospectively analyzed. All the patients had undergone cervical pedicle instrumentation under O-arm 3D navigation. Screw placement accuracy was analyzed and compared among different vertebral levels and also between different patient groups.
Results
A total of 241 cervical pedicle screws were inserted in 44 patients. Out of the 241 screws, 197 (81.74%) were inserted at the level of C3–C6 vertebrae with nearly equal distribution among the 4 vertebrae, followed by 32 (13.28%) and 12 (4.98%) screws at C2 and C7 vertebrae, respectively. After the analysis of screw placement as per Gertzbein classification, the overall breach rates were found to be 7.05% (17 screws) with 52.94% (10 screws) Grade I, 47.06% (7 screws) Grade II, and nil Grade III screw breaches.
Conclusion
The use of O-arm-based intra-operative 3D scans for navigation can make cervical pedicle screw placement reliable. High accuracy and better intra-operative control can increase surgeon’s confidence in using cervical pedicle instrumentation on more regular basis.
Graphical abstract
These slides can be retrieved under Electronic Supplementary Material.
Even though internal fixation has expanded the indications for cervical spine surgery, it carries the risks of fracture or migration, with associated potential life threatening complications. Removal of metal work from the cervical spine is required in case of failure of internal fixation, but it can become challenging, especially when a great amount of scar tissue is present because of previous surgery and radiotherapy.
Case presentation
We report a 16 year old competitive basketball athlete who underwent a combined anterior and posterior approach for resection of an osteosarcoma of the sixth cervical vertebra. Fourteen years after the index procedure, the patient eliminated spontaneously one screw through the intestinal tract via an oesophageal perforation and developed a severe dysphagia. Three revision surgeries were performed to remove the anterior plate because of the great amount of post-surgery and post-irradiation fibrosis.
Conclusions
Screw migration and oesophageal perforation after cervical spine surgery are uncommon potentially life-threatening occurrences. Revision surgery may be challenging and it requires special skills.
Several variations in the anatomy and injury of the lateral femoral cutaneous nerve (LFCN) have been studied since 1885. The aim of our study was to analyze the available data on the LFCN and find a true prevalence to help in the planning and execution of surgical procedures in the area of the pelvis, namely inguinal hernia repair.
Methods
A search of the major medical databases was performed for LFCN anatomy. The anatomical data were collected and analyzed.
Results
Twenty-four studies (n = 1,720) were included. The most common pattern of the LFCN exiting the pelvis was medial to the Sartorius as a single branch. When it exited in this pattern, it did so on average 1.90 cm medial to the anterior superior iliac spine (ASIS).
Conclusions
The LFCN and its variations are important to consider especially during inguinal hernia repair, abdominoplasty, and iliac bone grafting. We suggest maintaining a distance of 3 cm or more from the ASIS when operating to prevent injury to the LFCN.
The cervical spine is very complex, and it allows the largest range of motion relative to the rest of the spine. The fundamental function of the cervical spine is to maintain the head balanced over the trunk and to maintain horizontal gaze. The cervical spine must be both stable and flexible to guarantee function. Changes of the sagittal profile of the cervical spine may affect function and quality of life. The relationship between full body alignment and maintaining gaze necessitates a thorough understanding of the cranio-spino-pelvic alignment as a component of balance.
Question
Now the question is, what kind of sagittal profile does the cervical spine need for proper function? In the literature, normal sagittal alignment of the cervical spine is controversial. In general, there is the assumption that the alignment is lordotic. Does the data in the literature support this?
Results
The present literature review supports the following facts: Ideal cervical spine alignment is mostly lordotic, but not always; ideal cervical spine alignment can be lordotic, neutral or kyphotic; ideal cervical spine alignment is driven by the necessity of supporting the head and maintaining horizontal gaze; the cervical spine is in harmony with regional alignment (thoracic kyphosis) and sagittal global alignment (SVA):
TK (↑)?→?T1 Slope (↑)?→?CL (↑),
TK (↓)?→?T1 Slope (↓)?→?CL (↓),
SVA >50?mm: the cervical curve should be lordotic to maintain horizontal gaze,
SVA <0?mm: the cervical curve should be kyphotic to maintain horizontal gaze.
There is no consensus opinion on a definitive surgical management option for ranulas to curtail recurrence, largely from the existing gap in knowledge on the pathophysiologic basis.
Aim
To highlight the current scientific basis of ranula development that informed the preferred surgical approach.
Design
Retrospective cohort study.
Setting
Public Tertiary Academic Health Institution.
Method
A 7-year 7-month study of ranulas surgically managed at our tertiary health institution was undertaken—June 1, 2008–December 31, 2015—from case files retrieved utilising the ICD-10 version 10 standard codes.
Results
Twelve cases, representing 0.4 and 1.2% of all institutional and ENT operations, respectively, were managed for ranulas with a M:F = 1:1. The ages ranged from 5/12 to 39 years, mean = 18.5 years, and the disease was prevalent in the third decade of life. Main presentation in the under-fives was related to airway and feeding compromise, while in adults, cosmetic facial appearance. Ranulas in adults were plunging (n = 8, 58.3%), left-sided save one with M:F = 2:1. All were unilateral with R:L = 1:2. Treatment included aspiration (n = 2, 16.7%) with 100% recurrence, intra-/extraoral excision of ranula only (n = 4, 33.3%) with recurrence rate of 50% (n = 2, 16.7%), while marsupialisation in children (n = 1, 8.3%) had no recurrence. Similarly, transcervical approach (n = 5, 41.7%) with excision of both the ranula/sublingual salivary gland recorded zero recurrence. Recurrence was the main complication (n = 4, 33.3%).
Conclusion
With the current knowledge on the pathophysiologic basis, extirpation of both the sublingual salivary gland and the ranula by a specialist surgeon is key for a successful outcome.
To evaluate postoperative changes within the cervical alignment following surgical lumbar correction by pedicle subtraction osteotomy (PSO) in patients affected with sagittal global malalignment disease.
Methods
This was a monocentric, radiographic, and prospective study. 79 patients, who underwent sagittal correction by PSO, performed an EOS imaging pre- and postoperatively between January 2008 and December 2013 at the University Hospital of Bordeaux. Inclusion criteria were a performed pre- and postoperative EOS imaging and a preoperative C7SVA > 5 cm. Were excluded patients who did not allow EOS with a viewable cervical spine due to hyperkyphosis. The study involved the analysis of pelvic, lumbar, thoracic, cervical, and cranial parameters before and after the surgery.
Results
59 patients met the criteria. Mean follow-up was 38 months. The lumbar PSO significantly improved sagittal alignment including L1S1 lordosis, T1T12 kyphosis, and C7SVA (p < 0.001). We did not reported a significant change within cervical parameters after PSO (C2C7 lordosis 22.7°–21.5° p = 0.64, C1C7 lordosis 50.6°–48.8° p = 0.56, C1C2 angle 28.2°–27.9° p = 0.82, C7 slope stayed constant 32.3°–30.5° p = 0.47, OC2 angle 15.54°–15.56° p = 0.99). However, cranial slope decreased significantly (p < 0.05). We did not find correlation between lumbar lordosis and cervical lordosis variations (R = 0.265). Cervical lordosis was highly correlated with the C7 slope (R = 0.597) and with the Spino Cranial Angle (R = ? 0.867).
Conclusion
Reciprocal changes in cervical spine after PSO are difficult to approach. Maintaining a horizontal gaze involves locoregional mechanisms of compensation adapting to the slope of C7. The cranial system by decreasing the cranial slope allows the gaze alignment and is the first compensation mechanism to get involved after a loss of lumbar lordosis. Restoring optimal C7SVA is necessary to prevent the development of secondary cervical painful symptomatology when the cranial compensation is outdated.
