An analysis of the anatomic features of the cervical spine using computed tomography to select safer screw insertion techniques

Purpose

The purpose of the present study was to evaluate the anatomic features of the cervical spine using computed tomography (CT) to select safer screw insertion techniques, particularly emphasizing the location of the transverse foramen.

Methods

Fifty patients who underwent multiplanar CT reconstruction were evaluated. There were 34 males and 16 females with an average age of 67 years. The parameters included the following measurements: foramen width (the size of the transverse foramen FW), foramen height (the size of the transverse foramen FH), pedicle width (PW), foramen angle (FA the position of the transverse foramen), pedicle transverse angle (PTA) and lateral mass angle (LMA).

Results

The mean FW ranged from 6.2 to 6.3 mm (n.s). The mean FH ranged from 5.0 to 5.7 mm, with significant differences between each vertebra, except for the FH between C4 and C5 and the FH between C5 and C6. The mean PW ranged from 5.4 to 6.1 mm. There were significant differences between each vertebra, except for the PW between C3 and C4 and the PW between C3 and C5. The mean FA ranged from 18.8° to 20.5°. There were significant differences between each vertebra, except for the FA between C3 and C6 and the FA between C4 and C5. The mean PTA ranged from 37.1° to 45.4°. There were significant differences between each vertebra, except for the PTA between C3 and C5. The mean LMA ranged from 1.0° to 5.3°. There were significant differences between each vertebra, except for the LMA between C4 and C5. The FW and FH exhibited no correlations with PW, PTA or LMA. FA was found to be positively correlated with both PTA and LMA. There was also a positive correlation between PTA and LMA.

Conclusions

We suggest that in cases in which pedicle screw insertion is difficult, lateral mass screws (LMS) can be inserted safely and longer sizes can be selected. In contrast, in cases in which LMS insertion is difficult, the insertion of pedicle screws can be performed relatively easy.     

Modification of percutaneous vertebroplasty for painful old osteoporotic vertebral compression fracture in the elderly: preliminary report

ObjectiveTo study the clinical efficacy of modified percutaneous vertebroplasty (PVP) in the treatment of painful old osteoporosis vertebral compression fractures (OVCF).MethodsFrom April 2007 to October 2009, 16 cases (23 vertebrae) of symptomic old OVCF were treated with a modified PVP. Before operation, all the patients were examined by standing anteroposterior and lateral X-Ray and MRI. The pain level of each patient was assessed before operation and 1 week, 6, 12 months after the operation using visual analogue scale (VAS) and Oswestry disability index (ODI). The middle line vertebral body height and local sagittal Cobb's angle were also measured.ResultsPostoperative average VAS, Oswestry disability index (ODI), the local sagittal Cobb's angle decreased from 7.8, 72.3%, and 38.2° to 3.1, 26.8%, and 21.5° respectively before and after surgery (p < 0.05). The mean midline vertebral height increased from 13.8 mm to 26.6 mm before and after surgery (p < 0.05). There was no infection, nerve injury, pulmonary embolism, or death after operation.ConclusionsThe modified PVP can increase the space for bone cement filling and is good for the restoration of vertebral body height. It is an optimal procedure for the treatment of painful old OVCF.     

Comprehensive computed tomography assessment of the upper cervical anatomy: what is normal?

Background contextHigh-speed computed tomography (CT) exams have replaced traditional radiographs for assessment of cervical spine injuries in many emergency departments. Recent evidence demonstrates that even subtle displacements can indicate significant upper cervical spine injuries. Many different anatomical measurements have been described in the upper cervical spine to date, most of them based on X-ray. The range of anatomical relationships that exist in an uninjured population must be known to reliably detect abnormal relations. The measurements with the lowest normal variation are likely to be most useful in detecting injuries.PurposeThe purpose of this study was to describe the normal quantitative anatomical relationships as well as the threshold measurements most likely to detect injury in the upper cervical spine.Study design/SettingRetrospective anatomical case review.Patient sampleSeventy-six thin-sliced cervical CT scans randomly selected from a trauma population, all negative for injury in the cervical spine.MethodsForty-two different anatomical measurements were made of the upper cervical spine. These included traditional historical measurements and other detailed dimensions to characterize occipitocervical (OC) and atlantoaxial (AA) joint relationships.ResultsAfter review of all the anatomical measurements performed in the upper cervical spine, direct measurements of the joint space had the least variation. The mean OC joint space was 0.6 mm, with an upper 95% confidence interval (CI) of 1 mm at the most anterior or posterior aspects of the joints. This was true for both sagittal and coronal measurements. The mean AA joint space was 0.6 mm, with an upper 95% CI of 1.2 mm at the lateral aspect of the joint on the coronal image only. The midsagittal structures demonstrated significantly higher standard deviation and variability.ConclusionsThese results revealed consistently narrow joint spaces and left-right symmetry in the upper cervical spine joints that do not vary according to demographics. There was distinctly greater consistency in the coronal plane, which enabled more precise diagnostic measurement and side-to-side comparison of measurements. This precision will enable more accurate identification of abnormal scans, which should prompt consideration for additional workup. Thus, better understanding of these relationships may enable earlier detection of subtle craniocervical dissociative injuries based on CT scan data. This is important, because the only evidence of a severe injury on CT can be subtle misalignment.     

Computed tomographic-based morphometric study of thoracic spine and its relevance to anaesthetic and spinal surgical procedures

BackgroundTo collect a baseline computer software aided normative morphometric data of thoracic spine in the Indian population and analyze it to give pre-procedural guidelines to clinicians for safe surgical and anaesthetic procedures in the thoracic spine.MethodsCT scans of thoracic spine of patients free from spinal disorders were reviewed in a total of 600 vertebrae in 50 patients. Parameters recorded with the help of computer software were pedicle width, length and height, transverse pedicle angles, chord length, canal dimensions, body width and height, spinous process angle and transverse process length.ResultsPedicle width decreased from T1 (9.27 ± 1.01) to T4 (4.5 ± 0.93) and increased to T12 (8.31 ± 1.83). At T4 76% and at T5 62% of the pedicles were smaller than 5 mm and would not accept 4 mm screw with 1.0-mm clearance. However, at T1 2%, at T11 7% and at T12 8% would not accept a 4 mm screw. Chord length gradually increased in upper thoracic vertebrae and was relatively constant in middle and decreased in lower thoracic vertebrae. Shortest estimated chord length was at T1 (30.30 ± 2.11). On an average, from T1 to T6 and at T11 and T12, a screw length of 25–30 mm could be accommodated and from T7 to T10, 30–35 mm screw length could be accommodated. Transverse pedicle angle decreased from T1 (35.4 ± 2.21) to T12 (−9.8 ± 2.39). Canal dimensions were narrowest at T4/T5 (20.02 ± 1.23) in anteroposterior and 21.12 ± 1.23 in interpedicular diameters. Spinous process angle increased from T1 (30.11 ± 6.74) to T6 (57.89 ± 9.31) and decreased to 16.21 ± 7.38 at T12. Transverse process length increased from T1 to T7 (23.54 + 2.12 to 31.21 + 1.91) and then decreased to 12.11 + 2.3 at T12. Vertebral body dimensions showed increasing trends from T1 to T12.ConclusionsA thorough knowledge of anatomical and radiological characteristics of the spine and their variations is essential for the clinicians. Data collected in the present study provides baseline normative values in Indian population and will help in guiding safe and effective completion of both surgical and anaesthetic procedures in the thoracic spine. Computer software aided morphometric data can help in selecting appropriate size and optimal placement of the implant with minimal procedural difficulties and complications during spine surgery.     

The ipsilateral lamina–pedicle angle: can it be used to guide pedicle screw placement in the sub-axial cervical spine?

Pedicle screws in the sub-axial spine are infrequently used because of concerns over their safety and difficulty in placement, despite their superior pullout strength. In the sub-axial cervical vertebrae, we have observed that the lamina appears to project at right angles to the ipsilateral pedicle axis. The aim of this investigation was to confirm the lamina orientation as a reliable landmark for pedicle screw placement. 80 digital cervical spine CT were analysed. The angle formed by the ipsilateral outer lamina cortex to the pedicle axis was recorded. A total of 398 vertebrae were analysed from patients with a mean age of 39.5 years (range 18–78). Average axial lamina–pedicle angle ranged from 96.6° at C3 to 87.2° at C7 in males, and from 95.6° to 87.5° in females. The angle formed by the posterior cortex of the lamina and the ipsilateral pedicle shows a high level of consistency for sub-axial cervical vertebrae ranging from 96° at C3 to 87° at C7. Although the angle is not exactly 90° at all levels as hypothesised, the orientation of the lamina, nevertheless, forms a useful reference plane for insertion of pedicle screws in the sub-axial cervical spine.     

Biomechanical characterization of an annulus-sparing spinal disc prosthesis

Background contextCurrent spine arthroplasty devices require disruption of the annulus fibrosus for implantation. Preliminary studies of a unique annulus-sparing intervertebral prosthetic disc (IPD) found that preservation of the annulus resulted in load sharing of the annulus with the prosthesis.PurposeDetermine flexibility of the IPD versus fusion constructs in normal and degenerated human spines.Study design/settingBiomechanical comparison of motion segments in the intact, fusion and mechanical nucleus replacement states for normal and degenerated states.Patient settingThirty lumbar motion segments.Outcomes measuresIntervertebral height; motion segment range of motion, neutral zone, stiffness.MethodsMotion segments had multidirectional flexibility testing to 7.5 Nm for intact discs, discs reconstructed using the IPD (n=12), or after anterior/posterior fusions (n=18). Interbody height and axial compression stiffness changes were determined for the reconstructed discs by applying axial compression to 1,500 N. Analysis included stratifying results to normal mobile versus rigid degenerated intact motion segments.ResultsThe mean interbody height increase was 1.5 mm for IPD reconstructed discs versus 3.0 mm for fused segments. Axial compression stiffness was 3.0±0.9 kN/mm for intact compared with 1.2±0.4 kN/mm for IPD reconstructed segments. Reconstructed disc ROM was 9.0°±3.7° in flexion extension, 10.6°±3.4° in lateral bending, and 2.8°±1.4° in axial torsion that was similar to intact values and significantly greater than respective fusion values (p<.001). Mobile intact segments exhibited significantly greater rotation after fusion versus their more rigid counterparts (p<.05); however, intact motion was not related to motion after IPD reconstruction. The NZ and rotational stiffness followed similar trends. Differences in NZ between mobile and rigid intact specimens tended to decrease in the IPD reconstructed state.ConclusionThe annulus-sparing IPD generally reproduced the intact segment biomechanics in terms of ROM, NZ, and stiffness. Furthermore, the IPD reconstructed discs imparted stability by maintaining a small neutral zone. The IPD reconstructed discs were significantly less rigid than the fusion constructs and may be an attractive alternative for the treatment of degenerative disc disease.     

Ethnic differences in pedicle and bony spinal canal dimensions calculated from computed tomography of the cervical spine: a review of the English-language literature

Purpose

The aims of this study were to review published data on pedicle dimensions and bony spinal canal diameters calculated from CT examinations of the cervical spine through the English-language literature and analyze these data for ethnic disparities and similarities.

Materials and methods

The authors reviewed the literature on “pedicle” and “spinal canal” by conducting a bibliographic search using PubMed, Ovid MEDLINE, and Science Direct from January 1985 to December 2010. After evaluating all of the selected abstracts, we ultimately selected 19 studies involving living subjects: 12 studies on pedicle dimensions and 7 on spinal canal diameters. The four parameters, pedicle width (PW), pedicle transverse angle (PTA), anterior-posterior diameter of the spinal canal (APD), and transverse diameter of the spinal canal (TD), were analyzed at the relevant levels from C3 to C7. In addition, the values for pedicle dimensions and spinal canal diameters in the European/American populations were compared using the data from Asian populations as a baseline.

Results

The smallest mean PW was found at C4 in the male (5.1 mm) and female populations (4.1 mm); the largest mean PW was found at C7 in both male (7.7 mm) and female populations (7 mm). The PW in males was greater than in females at the majority of levels. The smallest mean PTA was found at C7 in both male (33.4°) and female populations (33°); the largest mean PTA was found at C4 in both male (53.2°) and female populations (52.1°). The overall PW, PTA, APD, and TD ratio of European/American to Asian populations was 91.4–98.8, 99.6–106.2, 110.7–122, and 100–108.3 %, respectively.

Conclusion

Although our cervical spine CT data were suggestive of possible ethnic differences in spinal canal morphology, our analysis failed to identify significant ethnic disparity in pedicle dimensions despite potential differences in physique between populations.     

C2–C3 vertebral disc angle: An analysis of patients with and without cervical spondylotic myelopathy

Study designRetrospective analysis.ObjectiveTo define C2–C3 vertebral disc angle (VDA) in patients with and without cervical spondylotic myelopathy.Summary of background dataC2–C3 VDA is a new radiological index of cervical spine alignment. Recent studies have suggested that high postoperative values are associated with greater mechanical complications in patients with cervical spondylotic myelopathy. However, normative values for patients without myelopathy has yet to be defined.MethodsPatients with and without cervical myelopathy between 2017 and 2019 were included. Inclusion criteria were patients above 18 years of age with antero-posterior (AP) and lateral (LAT) cervical X-rays. In the non-myelopathic group, patients were excluded if they had neurological symptoms or deficits, presence of cervical axial pain, previous spinal surgery, or diagnosis of either spondylolisthesis or scoliosis. In the myelopathic group, patients were excluded if they had previous spinal surgery. Radiological indices evaluated include: C2–C3 disc angle, C2–C7 Cobb angle, C7 sagittal vertical axis, T1 slope.ResultsIn total, 99 patients without myelopathy and 22 patients with myelopathy were identified and analyzed. In patients without myelopathy, the mean for C2–C3 VDA was 25.9 ± 7.9. For patients with myelopathy, preoperative values were 24.4 ± 10.0 and 27.1 ± 7.9 postoperatively. No statistically significant differences were found between patients with and without myelopathy. C2–C3 disc angle was not correlated with age (R = −0.173).ConclusionThis study did not find statistically significant differences in C2–C3 VDA values between patients with and without cervical myelopathy. This study provides normative data for C2–C3 vertebral disc angle in patients with and without cervical spondylotic myelopathy. Furthermore, C2–C3 vertebral disc angle may be independent from age.     

Cervical pedicle screw fixation at C6 and C7: A cadaveric study

Background:Cervical pedicle screw fixation is an effective method for treating traumatic and non traumatic injuries. But many studies have reported higher incidence of cervical pedicle penetration, so many research efforts have aimed at improving the accuracy of cervical screw fixation. Most of the anatomical studies on cervical pedicle screw placement previously published focused on the measurements of anatomical parameters, the entry point of pedicle screw is vague. We preliminarily designed a C3, C4 and C5 pedicle screw fixation method that had clear entry point and clinical cases confirmed that this method is feasible and safe. So we did this study of cervical pedicle screw fixation for C6 and C7 vertebrae.Results:In C6, the PW and PH were 6.12 ± 0.78 and 7.48 ± 0.81 mm, respectively. In C7, the PW and PH were 6.85 ± 0.73 and 8.03 ± 0.38 mm, respectively. The LSC was 30.83 ± 0.91 mm. Two E angles were identified, namely E1 and E2 and their values were 89.61 ± 1.24 and 59.71 ± 1.10°, respectively. Meanwhile, F averaged 75.86 ± 1.12°.Conclusion:The intersection of the horizontal line through the midpoint of the transverse process root and vertical line through the intersection of the posterolateral and posterior planes of the isthmus can be used as an entry point for C6 and C7 pedicle screw fixation. The screws should be inserted at 60 or 90° with the posterolateral isthmus in the horizontal plane and at 75° with the posterior isthmus in the sagittal plane. The LSC should not exceed 30 mm.     

Magnetic resonance imaging in patellar lateral femoral friction syndrome (PLFFS): prospective case-control study

ObjectivesTo describe morphologic abnormalities and signs of patellar lateral femoral friction syndrome (PLFFS) detected by magnetic resonance imaging (MRI).Materials and methodsProspective study of 56 knees (21 patients and 30 controls) studied by 3 Tesla MRI. Comparative analysis of clinical data, quantitative and qualitative imaging criteria in a population of patients with anterior knee pain associated with an abnormal MRI signal along the lateral alar folds of the infrapatellar fat pad, a characteristic sign of PLFFS, and a control population with no anterior knee pain or abnormal signal from the infrapatellar fat pad.ResultsPatients with PLFFS have anterior and/or lateral knee pain. Their knee has anatomical predispositions for instability, primarily with patella alta (P < 0.0001), patellar tilt more than 13.5° (P < 0.0001), a patellar nose length less than 9 mm (P = 0.0037), a patellar nose ratio less than 0.25 (P < 0.0001), a TT-TG distance more than 10 mm (P < 0.0001), and a trochlear prominence more than 4 mm (P = 0.0056). In 35% of patients, patellar chondropathy is visible, and 48% of patients have patellar or trochlear subchondral abnormalities.ConclusionAnterior, lateral, and medial knee pain may be related to PLFFS. Anatomical predispositions contributing to instability are found in these patients. There may be associated chondropathies and osteochondropathies.     

Subaxial cervical vertebrae in patients with juvenile idiopathic arthritis – Something special?

ObjectivesTo describe the main dimensions of the cervical vertebrae and spinal canal in two groups with juvenile idiopathic arthritis (JIA) and a non-inflammatory control group.MethodsThere were altogether 158 female patients in three different groups included in the study: a group with severe, complicated JIA (sJIA), a population based JIA group (pJIA), and fibromyalgia patients as a non-inflammatory control group (pFM). The patients’ clinical records and cervical spine radiographs taken in adult age (>17 years) were evaluated.ResultsThe patients with sJIA had the mean area of the 3rd–6th cervical vertebrae bodies and the average width and height of the 3rd–6th cervical vertebrae bodies significantly smaller than the patients in the pJIA and pFM groups. The mean value of the maximal difference between the successive vertebral body areas of each individual was significantly larger in the sJIA group than the other groups (p = 0.047; the body height adjusted). There were no significant differences in the mean diameter of the sagittal spinal canal between study groups.ConclusionsInflammatory changes of the cervical spine are common, and growth disturbances of cervical vertebrae in patients with JIA have been described previously. We found that patients with severe complicated JIA have a smaller cervical vertebral body size in general. They also have more differences in the sizes of their own vertebrae, representing growth disturbances of individual vertebral bodies. This is probably caused by the inflammatory disease and/or its more aggressive pharmacotherapy. The spinal canal diameter was only slightly smaller in the sJIA group. Thus the disturbed growth of the vertebral body in sJIA does not, in general, increase the risk of spinal canal compression.     

‘Higher the grade-smaller the pedicle’: a study of pedicle dimensional variations in 100 cases of high grade lytic spondylolisthesis

Purpose

To measure the pedicle dimensions in high grade lytic spondylolisthesis (HGL) and to classify them, which helps the spine surgeon in proper selection of pedicle screws.

Methods

A study of CT scans in 100 consecutive patients between Jan 2017 and April 2021 diagnosed as single-level HGL on standing radiographs. Pedicle height (PH), Pedicle width (PW), Differential pedicle height (DPH), Screw length (SL) and Transverse pedicle angle (TPA) were measured and analyzed. PH and PW were classified into four grades as—grade A less than 5.0 mm, grade B between 5.0 and 6.0 mm, grade C between 6.0 and 7.0 mm, and grade D above 7.0 mm.

Results

5 males and 95 females with mean age of 49.1 years. PH in 44% lytic vertebra were grade A, B (less than 6 mm) and the rest 56% had grade C, D (greater than 6 mm). PH averaged 6.6 mm in grade 3 HGL, 5.61 mm in grade 4 HGL. Change in PW, SL and TPA was not statistically significant with regards to grade or level of listhesis. A total of 37 cases were noted to have DPH (25 cases had a difference < 2 mm and 12 had a difference > 2 mm).

Conclusion

44% of the PH in lytic vertebra was grade A and B (less than 6 mm) that stresses the importance of pre-op CT assessment and planning the appropriate screw dimensions. Change in PH was statistically significant with regards to the grade of listhesis (P-value < 0.01). Differential pedicle height also need to be looked for.

     

Minimally invasive treatment of displaced femoral shaft fractures with a teleoperated robot-assisted surgical system

BackgroundMinimally invasive surgical operation of intramedullary (IM) nailing is a standard technique for treating diaphyseal fractures. However, in addition to its advantages, there are some drawbacks such as the frequent occurrence of malalignment, physical fatigue and high radiation exposure to medical staff. The use of robotic and navigation techniques is promising treatments for femoral fractures.Materials and methodsThis paper presents a novel robot-assisted manipulator for femoral shaft fracture reduction with indirect contact with the femur. An alternative clinical testing model was proposed for orthopedic surgeons to practice femoral fracture reduction. This model imitates the human musculoskeletal system in shape and functional performance. The rubber tube simulate muscles providing contraction forces, and the silicone simulates passive elasticity of muscles. Two-group experiments were performed for studying feasibility of the teleoperated manipulator.ResultsThe average operative time was about 7 min. In the first group experiments, the femur axial, antero-posterior (AP) and lateral views mean errors were 2.2 mm, 0.7 mm and 1.1 mm, respectively, and their maximums were 3.0 mm, 0.9 mm and 1.5 mm; the mean errors of rotation were 0.8° around x-axis, 1.6° around y-axis, 2.0° around z-axis, and their maximums were 1.1°, 2.2°, 2.9°, respectively. For the second group experiments, the femur axial, AP and lateral views mean errors were 1.8 mm, 0.4 mm and 0.8 mm, respectively, and their maximums were 2.2 mm, 0.7 mm and 1.1 mm; the mean errors of rotation were 1.2° around x-axis, 1.6° around y-axis, 1.9° around z-axis, and their maximums were 2.4°, 1.8°, 2.7°, respectively. Reduction for AP view displacement is easier than lateral (p < 0.05) because of the tube-shaped anatomy and the muscle contraction forces. Errors around x-axis are smaller than those around y-, and z- axes (p<0.05), i.e., electro-mechanical actuator is easier to control than pneumatic.ConclusionAn experimental model for simulating human femoral characteristics was proposed. Experiments conducted on the artificial lower limb model demonstrated high reduction accuracy, safety, sufficient working space, and low radiation exposure of the proposed robot-assisted system. Thus, the minimally invasive teleoperated manipulator would have greater development prospect.     

Effect of intervertebral disc height on postoperative motion and clinical outcomes after Prodisc-C cervical disc replacement

Background contextCervical total disc replacement (TDR) is an emerging technology. However, the factors that influence postoperative range of motion (ROM) and patient satisfaction are not fully understood.PurposeTo evaluate the influence of pre- and postoperative disc height on postoperative motion and clinical outcomes.Study design/settingRetrospective review of patients enrolled in prospective randomized Food and Drug Administration (FDA) trial.Patient sampleOne hundred sixty-six patients with single-level ProDisc-C arthroplasty performed were evaluated.Outcome measuresROM and clinical outcomes based on Neck Disability Index (NDI) and Visual Analog Scale (VAS) were assessed.MethodsPreoperative and postoperative disc height and ROM were measured from lateral and flexion-extension radiographs. Student t test and Spearman's rho tests were performed to determine any correlation or “threshold” effect between the disc height and ROM or clinical outcome.ResultsPatients with less than 4 mm of preoperative disc height had a mean 1.8° increase in flexion-extension ROM after TDR, whereas patients with greater than 4 mm of preoperative disc height had no change (mean, 0°) in flexion-extension ROM (p=.04). Patients with greater than 5 mm of postoperative disc height have significantly higher postoperative flexion-extension ROM (mean, 10.1°) than those with less than 5 mm disc height (mean, 8.3°, p=.014). However, patients with greater than 7 mm of postoperative disc height have significantly lower postoperative lateral bending ROM (mean, 4.1°) than those with less than 7 mm disc height (mean, 5.7°, p=.04). It appears that the optimal postoperative disc height is between 5 and 7 mm for increased ROM on flexion extension and lateral bending. There was a mean improvement of 30.5 points for NDI, 4.3 points for VAS neck pain score, and 3.9 points for VAS arm pain score (all p<.001). No correlation could be found between clinical outcomes and disc height. Similarly, no threshold effect could be found between any specific disc height and NDI or VAS.ConclusionPatients with greater disc collapse of less than 4 mm preoperative disc height benefit more in ROM after TDR. The optimal postoperative disc height range to maximize ROM is between 5 and 7 mm. This optimal range did not translate into better clinical outcome at 2-year follow-up.     

When does intraoperative 3D-imaging play a role in transpedicular C2 screw placement?

IntroductionThe stabilization of an atlantoaxial (C1-C2) instability is demanding due to a complex atlantoaxial anatomy with proximity to the spinal cord, a variable run of the vertebral artery (VA) and narrow C2 pedicles. We perfomed the Goel & Harms fusion in combination with an intraoperative 3D imaging to ensure correct screw placement in the C2 pedicle. We hypothesized, that narrow C2 pedicles lead to a higher malposition rate of screws by perforation of the pedicle wall. The purpose of this study was to describe a certain pedicle size, under which the perforation rate rises.Patients and methodsIn this retrospective study, all patients (n = 30) were operated in the Goel & Harms technique. The isthmus height and pedicle diameter of C2 were measured. The achieved screw position in C2 was evaluated according to Gertzbein & Robbin classification (GRGr).ResultsA statistically significant correlation was found between the pedicles size (isthmus height/pedicle diameter) and the achieved GRGr for the right (p = 0.002/p = 0.03) and left side (p = 0.018/p = 0.008). The ROC analysis yielded a Cut Off value for the pedicle size to distinguish between an intact or perforated pedicle wall (GRGr 1 or ≥2). The Cut-Off value was identified for the isthmus height (right 6.1 mm, left 5.4 mm) and for the pedicle diameter (6.6 mm both sides).ConclusionThe hypothesis, that narrow pedicles lead to a higher perforation rate of the pedicle wall, can be accepted. Pedicles of <6.6 mm turned out to be a risk factor for a perforation of the pedicle wall (GRGr 2 or higher). Intraoperative 3D imaging is a feasible tool to confirm optimal screw position, which becomes even more important in cases with thin pedicles. The rising risk of VA injury in these cases support the additional use of navigation.     

Interscalene brachial plexus block for scapular and upper chest pain due to cervical radiculopathy: a randomized controlled clinical trial

BackgroundAnimal experiments have shown that one of the pathways for pain originating from the cervical spine is the sympathetic trunk. However, there have been few reports regarding the cervical pain pathway and efficacy of interscalene brachial plexus block for upper limb, scapular and chest pain originating in the cervical spine in clinical cases. The purpose of the present study was to clarify the efficacy of interscalene brachial plexus block for upper limb, scapular and chest pain.MethodsPatients (137 men and 223 women) who had cervical radicular pain were studied. The intensity of upper limb, scapular and chest pain was measured by using a VAS before injection and at 5 min and 7 days after injection. To evaluate the efficacy of interscalene brachial plexus block, patients with cervical radicular pain who had received NSAIDs for at least 2 weeks were randomized to interscalene brachial plexus block or control block groups. VAS scores were compared to assess the effects of injection and the pain pathway.ResultsThe average VAS score for upper limb pain with or without scapular and chest pain was significantly reduced by interscalene brachial plexus block compared with control block at 5 min and 7 days after injection. After interscalene brachial plexus block, 89 patients reported symptoms of stellate ganglion block versus no patients after control block. Scapular and chest pain was significantly reduced in the patients with stellate ganglion block compared to those without stellate ganglion block.ConclusionsInterscalene brachial plexus block is useful for upper limb, scapular and chest pain due to disorders of the cervical spine. The scapular and chest pain pathway is more likely to be interrupted by an interscalene brachial plexus block that causes a stellate ganglion block compared to an interscalene brachial plexus block without stellate ganglion block.     

The geometrical axis of the talocrural joint—Suggestions for a new measurement of the talocrural joint axis

BackgroundDespite intensive research there is no consensus about the talocrural joint axis. The aim of the present study is a new method to determinate the geometric rotational axis of the talocrural joint.MethodsWe analyzed 98 CT-scans of full cadaver Caucasian legs. We generated three-dimensional reconstruction models of the talus. A best fitting cone was orientated to the talar articular surface. The geometric rotational axis was defined to be the axis of this cone.ResultsThe geometric rotational axis of the talocrural joint is orientated from lateral–distal to medial–proximal (85.6° ± 10 compared to anatomical tibial axis in torsional plane), from posterior–distal to anterior–proximal (81.43° ± 44.35 compared to anatomical tibial axis in sagittal plane) and from posterior–medial to anterior–lateral (169.2° ± 5.91 compared to intermalleolar axis in axial plane).ConclusionsThe consideration of our results might be helpful for better understanding of ankle biomechanics.     

Outcomes for four-part proximal humerus fractures treated with a locking compression plate and an autologous iliac bone impaction graft

ObjectivesThe study aims to evaluate outcomes of autologous iliac bone impaction grafts (AIBIGs) with locking-compression plates (LCPs) in four-part proximal humeral fracture.MethodsBetween October 2004 and October 2008, 21 AIBIG with LCP osteosyntheses were done for four-part proximal humeral fractures. Patients included seven males and 14 females. Their mean age at the time of the operation was 66.3 ± 16.9 years (range: 24–87 years). Five patients had high-energy fractures other than fall from standing height. There were two fracture-dislocation cases, and three valgus-impacted fractures. The length of the calcar segment attached to the articular segment was 7.04 ± 6.10 mm; 13 of the 21 cases had lengths less than 8 mm. Medial-hinge displacement was 16.77 ± 15.84 mm; 19 of the 21 cases had displacements more than 2 mm.ResultsThere was no avascular necrosis of the humeral head and union was achieved in all cases. Varus collapse and hardware-related complications were not observed. Postoperative neck-shaft angles were found to be 129 ± 9° (range: 109–146°). Neer scores were 92.0 ± 6.3 (range: 81–100).ConclusionThe results of using AIBIG with LCP for four-part proximal humeral fractures are excellent. There are significant bone defects in osteoporotic or comminuted fractures and LCP alone does not always provide reliable fixation. Therefore, meticulous technique and use of AIBIG in this complicated type of fracture can ensure a favourable outcome.     

Computer navigation in the reduction and fixation of femoral shaft fractures: a randomized control study

ObjectivesWe investigated the accuracy of reduction of intramedullary nailed femoral shaft fractures in human cadavers, comparing conventional and computer navigation techniques.MethodsTwenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9 to 53 mm in length (Winquist 3–4, AO 32C2). All fractures were fixed with antegrade 9 mm diameter femoral nails on a radiolucent operating table. Five fractures (“Fluoro” group) were fixed with conventional techniques and fifteen fractures (“Nav 1” and “Nav 2” groups) with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. Postoperative CT scans compared femoral length and rotation with the normal leg.ResultsMean leg length discrepancy in the computer navigation groups was smaller, namely, 3.6 mm for Nav 1 (95% CI: 1.072 to 6.128) and 4.2 mm for Nav 2 (95% CI: 0.63 to 7.75) vs. 9.8 mm for Fluoro (95% CI: 6.225 to 13.37) (p < 0.023). Mean rotational discrepancies were 8.7° for Nav 1 (95% CI: 4.282 to 13.12) and 5.6° for Nav 2 (95% CI: ?0.65 to 11.85) vs. 9.0° for Fluoro (95% CI: 2.752 to 15.25) (p = 0.650).ConclusionsComputer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to leg length, but not rotational deformity.     

Cross-sectional area of the posterior extensor muscles of the cervical spine in whiplash injury patients versus healthy volunteers--10 year follow-up MR study

IntroductionLong-term follow-up studies focusing on the posterior extensor muscles in patients suffering from whiplash injury are scarce. The purpose of this study was to elucidate the changes in the posterior extensor muscles 10 years after whiplash injury.MethodsTwenty-three patients who had suffered from whiplash injury in 1994–1996 and had undergone MRI using a 1.5-T superconductive imager participated in this follow-up study (13 males, 10 females, mean age 51.8 years, mean follow-up 11.5 years). In addition, 60 healthy volunteers who had undergone MRI in the same period were included as controls (36 males, 24 females, mean age 47.8 years, mean follow-up 11.1 years). All participants underwent follow-up MRI. The cross-sectional areas of the deep posterior muscles (CSA) including the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis were digitally measured at C3-4, C4-5, and C5-6 using NIH image. The long-term changes in the CSA were compared between the two groups. In addition, correlations between the CSA and cervical spine-related symptoms were evaluated.ResultsThe mean total CSA per patient (the sum of the area from C3-4 to C5-6) was 4811.6 ± 878.4 mm² in the whiplash patients and 4494.9 ± 1032.7 mm² in the controls at the initial investigation (p = 0.20), and 5173.4 ± 946.1 mm² and 4713.0 ± 1065.3 mm² at the follow-up (p = 0.07). The mean change in CSA over time was 361.8 ± 804.9 mm² in the whiplash patients and 218.1 ± 520.7 mm² in the controls (p = 0.34). Ten whiplash patients (43.5%) had neck pain and 11 (47.8%) had shoulder stiffness. However, there was no difference in the change in CSA over time between the symptomatic and asymptomatic patients.ConclusionsThere was no significant difference in the change in CSA between whiplash patients and healthy volunteers after a 10-year follow-up period. In both groups, the cross-sectional area slightly increased at follow-up. In addition, there was no association between the change in CSA and clinical symptoms such as neck and shoulder pain. These results suggest that whiplash injury is not associated with symptomatic atrophy of the posterior cervical muscles over the long term.