Pedicle screw augmentation in posterior constructs of the thoracolumbar spine: How many pedicle screws should be augmented?

BACKGROUNDS: To evaluate the effects of different pedicle screw augmentation strategies on screw loosening and adjacent segment collapse at the proximal end of long-segment instrumentation. METHODS: Eighteen osteoporotic (9 male, 9 female donors; mean age: 74.7 ± 10.9 [SD] years) thoracolumbar multi-segmental motion segments (Th11 - L1) were assigned as follows: control, one-level augmented screws (marginally), and two-level augmented screws (fully augmented) groups (3 × 6). Pedicle screw placement was performed in Th12 and L1. Cyclic loading in flexion started with 100-500 N (4 Hz) and was increased by 5 N every 500 cycles. Standardized lateral fluoroscopy images with 7.5 Nm loading were obtained periodically during loading. The global alignment angle was measured to evaluate the overall alignment and proximal junctional kyphosis. The intra-instrumental angle was used to evaluate screw fixation. FINDINGS: Considering screw fixation as a failure criterion, the failure loads of the control (683 N), and marginally (858 N) and fully augmented (1050 N) constructs were significantly different (ANOVA p = 0.032).Taking the overall specimen alignment as failure criteria, failure loads of the three groups (control 933 ± 271.4 N, marginally 858 N ± 196 N, and full 933 ± 246.3 N were in the same range and did not show any significance (p = 0.825). INTERPRETATION: Global failure loads were comparable among the three groups and unchanged with augmentation because the adjacent segment and not the instrumentation failed first. Augmentation of all screws showed significant improved in screw anchorage.

Clinical and radiological outcome of Mason-Johnston types III and IV radial head fractures treated by an on-table reconstruction.

BACKGROUND: Only few methods treating comminuted radial head fractures have been established providing sufficient joint reconstruction, restoring radial length and enabling early joint mobilization. When an anatomical reconstruction using open reduction and internal fixation is not possible, radial head resection or primary arthroplasty is often conducted. An "Ex situ/on-table" reconstruction is widely disregarded but can be an option. The purpose of this study was to evaluate the functional and radiological outcome of comminuted radial head fractures treated with an "on-table" reconstruction and internal fixation using a low profile plate. METHODS: Fourteen patients who sustained a radial head fracture (9 Mason-Johnston type III and 5 Mason-Johnston type IV) and were treated with an "on-table" reconstruction between 2010 and 2020 were evaluated retrospectively. The patients mean age was 41.3 years (range 21-69). The clinical evaluation included active range of motion, grip strength, pain level and elbow stability. The functional outcome was assessed using the Disability of Arm, Shoulder and the Hand (DASH) score, Mayo Elbow Performance Index (MEPI), Broberg and Morrey score. The radiological examination included a.p. and lateral views of the injured elbow to evaluate nonunions, loss of reduction, joint alignment, avascular radial head necrosis, heterotopic ossifications and posttraumatic osteoarthritis. RESULTS: The inclusion rate was 74% with a mean follow-up of 50 months (range 16-128). The mean elbow flexion of the injured side was 126° (range110-145°) with an average extension loss of 8° (range 0-40°). Pronation was 65° (15-90°) and supination 66° (5-90°). The mean MEPI was 87 points (range 45-100). The mean DASH score was 13 points (range 1-88). According to the Broberg and Morrey functional scoring system, the average score was 92 points (range 88-100). Complete bone union was achieved in 9 cases, partial union in 4 cases and nonunion in one case. There were no signs of avascular necrosis of the radial head. Signs of post-traumatic osteoarthritis were seen in 11 cases. Five patients needed an implant removal due to a radio-ulnar impingement and one patient a revision surgery due to the nonunion and implant breakage. CONCLUSIONS: An on-table (ex situ) reconstruction of the radial head is a reliable option with a good clinical outcome and low complication rate in the surgical treatment of comminuted radial head fractures. It can restore joint alignment and maintain radial length. The risk for avascular necrosis is neglectable, and the bone healing rate is high.

Bilateral medial medullary syndrome following anterior screw fixation of type 2 odontoid fracture, a case report of two patients.

INTRODUCTION: Medial medullary syndrome (MMS) has not been reported after anterior screw fixation of an odontoid type 2 fracture. CASE PRESENTATION: We report on two cases who suffered from an unstable type 2 odontoid fracture following a skiing and a domestic fall accident. Prior to anterior screw fixation surgery both patients presented without neurologic deficits but postoperatively developed a bilateral MMS, including an incomplete tetraparesis, impaired sensation of position and movement as well as tactile discrimination and paralysis of the tongue muscle with deviation to the paralyzed side. MRI showed a typical heart-shaped ischaemic lesion in the medial medulla bilaterally. The search for aetiologic factors was uneventful in both patients except for severe atherosclerosis. DISCUSSION: Due to the close proximity of the ischaemic area to the surgical site, we here propose the perioperative mechanical manipulation of the upper cervical spine during surgery of patients with atherosclerosis as a new aetiology for MMS.

Linear Anterior-Posterior Computed Tomography Parameters Used to Quantify Trochlear Dysplasia Are More Reliable Than Angular Measurements.

PURPOSE: (1) To evaluate the reliability of 9 commonly used quantitative parameters of the trochlear morphology on computed tomography (CT) and (2) to analyze for differences in the reliability regarding patient subgroups (patellofemoral instability [PFI] vs non-PFI). METHODS: A retrospective analysis of lower-limb CT scans performed between August 1996 and February 2013 was performed. The CT scans of all patients with PFI and 30 randomly selected cases without a history of PFI (non-PFI) were included. The following measurements were performed on 1 proximal axial CT slice at the entrance of the trochlear groove and 1 slice 5 mm further distal: relative medial, central, and lateral trochlear height; trochlear depth; relative transverse trochlear shift; trochlear facet asymmetry; sulcus angle; and medial and lateral trochlear slope. Four investigators performed the measurements independently, and intraclass correlation coefficients (ICCs) were calculated for the entire study group, as well as for the PFI and non-PFI groups separately. RESULTS: In total, 66 cases (36 PFI cases) were included in the study. We found almost perfect inter-rater and intrarater agreement for the trochlear height on both axial CT slices (ICC, 0.831-0.977). For the other measurements, we found only fair reliability (ICC < 0.4) on the proximal CT slice, whereas on the distal CT slice, at least moderate reliability (ICC > 0.4) was observed. ICCs were lower for many parameters in the PFI group. Angular values were less reliable than linear values. In particular, measurements involving the medial facet (i.e., sulcus angle, medial trochlear slope, and trochlear facet asymmetry) were less reliable. CONCLUSIONS: When interpreting quantitative parameters defining the trochlear morphology, one must taken into account the considerably lower reliability of angular parameters such as the commonly used sulcus angle compared with linear measurements. Radiologic measurements are less reliable in cases of PFI than in subjects without instability. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

The negative impact of the COVID-19 lockdown on pain and physical function in patients with end-stage hip or knee osteoarthritis.

PURPOSE: The purpose of this study was to evaluate pain, functional impairment, mental health, and daily activity in patients with end-stage hip and knee osteoarthritis (OA) during the COVID-19 lockdown. METHODS: The study included 63 patients, with hip or knee OA, who had been scheduled for arthroplasty that was postponed because of COVID-19. Patients were evaluated by telephone interviews during the first week after lockdown, in the fourth week, and again at the end of the lockdown. Patients rated their pain level on the basis of a visual analog scale (VAS) and completed WOMAC, SF-12 and Tegner activity scale (TAS) questionnaires. RESULTS: VAS and WOMAC scores increased significantly during lockdown, while physical activity significantly decreased. At the final evaluation, VAS and WOMAC showed a significant negative correlation with TAS. The SF-12 subscale scores showed a significant decrease of the physical component during the lockdown, while the mental component remained largely unchanged. Patients with knee OA showed a faster progress of pain compared to those with hip OA. 50 patients (79%) stated they wished to have arthroplasty as soon as possible. CONCLUSION: The COVID-19 lockdown had a significant impact on pain, joint function, physical function, and physical activity in patients with end-stage hip and knee OA. LEVEL OF EVIDENCE: II (Prospective cohort study).

Cervical Disc and Ligamentous Injury in Hyperextension Trauma: MRI and Intraoperative Correlation.

BACKGROUND AND PURPOSE: To identify and evaluate diagnostic magnetic resonance imaging (MRI) features in patients with suspicion of discoligamentous cervical injury after hyperextension trauma of the cervical spine. METHODS: MR images with a standard protocol (1.5 T, including sagittal T2-weighted images and short tau inversion recovery [STIR]) in 21 patients without any sign of fracture or instability on multidetector computed tomography of the cervical spine were assessed. Among other structures we evaluated the following: prevertebral hematoma, anterior longitudinal ligament (ALL), intervertebral disc, and spinal cord. Presence and the anatomic level of injury were identified and recorded. Results were then compared with intraoperative findings as a reference standard. Simple descriptive statistical analysis, agreement coefficients (given by calculating the percent agreement), and the determination of Gwet's AC1 coefficient were used to analyze our results. RESULTS: The overall percent agreement between STIR and intraoperative findings was 90.9% (AC1 = .881) and for T2 69.7% (AC1 = .498). For the ALL, the overall agreement was 87.9% (AC1 = .808) and for the intervertebral disc 78.8% (AC1 = .673), in which STIR always showed a higher agreement. Prevertebral hematoma was found in 20 of 21 patients with the maximum thickness at the same anatomic level as the intraoperatively proven lesion in 12 of 18 patients (67%). Edema and/or hemorrhage of the spinal cord was shown in 16 of 21 being at the same anatomic level as the intraoperatively confirmed pathology in 16 of 16 patients (100%). CONCLUSIONS: MRI is a reliable tool for the evaluation of discoligamentous injuries in the cervical spine, with ancillary features proven as helpful information.

Functional and radiographic evaluation of an interspinous device as an adjunct for lumbar interbody fusion procedures.

In the last decades, several interspinous process devices were designed as a minimally invasive treatment option for spinal stenosis. In order to minimise surgical trauma, interspinous process devices were recently discussed as an alternative posterior fixation in vertebral interbody fusions. Therefore, the purpose of this study was to evaluate the effect of a newly designed interspinous device with polyester bands (PBs) on range of motion (RoM) and centre of rotation (CoR) of a treated motion segment in comparison with an established interspinous device with spikes (SC) as well as with pedicle screw instrumentation in lumbar fusion procedures. Flexibility tests with an applied pure moment load of 7.5 Nm were performed in six monosegmental thoracolumbar functional spinal units (FSUs) in the following states: (a) native, (b) native with PB device, (c) intervertebral cage with PB device, (d) cage with SC and (e) cage with internal fixator. The resulting RoM was normalised to the native RoM. The CoR was determined of X-ray images taken in maximal flexion and extension during testing. In flexion and extension, the PB device without and with the cage reduced the RoM of the native state to 58% [standard deviation (SD) 17.8] and 53% (SD 15.7), respectively. The SC device further reduced the RoM to 27% (SD 16.8), while the pedicle screw instrumentation had the most reducing effect to 17% (SD 17.2) (p < 0.01). In lateral bending and axial rotation, the interspinous devices had the least effect on the RoM. Compared to the native state, for all instrumentations the CoR showed a small shift towards cranial. In the anterior-posterior direction, the SC device and the pedicle screw instrumentation shifted the CoR towards the posterior wall. The interspinous devices significantly reduced the RoM in flexion/extension, while in axial rotation and lateral bending only the internal fixator had a significant effect on the RoM.

Biomechanical Study of a Novel, Expandable, Non-Metallic and Radiolucent CF/PEEK Vertebral Body Replacement (VBR).

Vertebral body replacement is well-established to stabilize vertebral injuries due to trauma or cancer. Spinal implants are mainly manufactured by metallic alloys; which leads to artifacts in radiological diagnostics; as well as in radiotherapy. The purpose of this study was to evaluate the biomechanical data of a novel carbon fiber reinforced polyetheretherketone (CF/PEEK) vertebral body replacement (VBR). Six thoracolumbar specimens were tested in a six degrees of freedom spine tester. In all tested specimens CF/PEEK pedicle screws were used. Two different rods (CF/PEEK versus titanium) with/without cross connectors and two different VBRs (CF/PEEK prototype versus titanium) were tested. In lateral bending and flexion/extension; range of motion (ROM) was significantly reduced in all instrumented states. In axial rotation; the CF/PEEK combination (rods and VBR) resulted in the highest ROM; whereas titanium rods with titanium VBR resulted in the lowest ROM. Two cross connectors reduced ROM in axial rotation for all instrumentations independently of VBR or rod material. All instrumented states in all planes of motion showed a significantly reduced ROM. No significant differences were detected between the VBR materials in all planes of motion. Less rigid CF/PEEK rods in combination with the CF/PEEK VBR without cross connectors showed the smallest reduction in ROM. Independently of VBR and rod material; two cross connectors significantly reduced ROM in axial rotation. Compared to titanium rods; the use of CF/PEEK rods results in higher ROM. The stiffness of rod material has more influence on the ROM than the stiffness of VBR material.

Ultrasound melted polymer sleeve for improved primary pedicle screw anchorage: A novel augmentation technique.

BACKGROUND: Cement augmentation of pedicle screws to prevent screw loosening is associated with significant complications, such as cement leakage or bone necrosis. Therefore, an alternative strategy to improve pedicle screw anchorage has been recently developed: Polymer reinforcement of pedicle screws uses an in situ melted polymer sleeve in order to enhance screw anchorage. This biomechanical study evaluated the effect of polymer-reinforcement by comparing polymer-reinforced pedicle screws to non-augmented as well as cement-augmented screws under cyclic loading. METHODS: For each of the two comparisons (polymer-reinforced vs. non-augmented screws and polymer-reinforced vs. cement-augmented screws), polymer-reinforced screws and control screws were placed into the left and right pedicle of seven vertebrae (mean age: 74.0 (SD 9.3) years) to allow for pairwise left-right comparisons. Each screw was subjected to cyclic cranio-caudal loading with an initial load ranging from -50 N to +50 N and with stepwise increasing compressive loads (5 N every 100 cycles) until screw loosening. FINDINGS: Polymer-reinforced pedicle screws resisted a higher number of load cycles until loosening than the contralateral non-augmented control screws (4300 SD 2018 vs. 2457 SD 1116 load cycles, p = 0.015). Screw anchorage of polymer-reinforced pedicle screws was comparable to that of cement augmented control screws (3857 (SD2085) vs. 4300 (SD1257) load cycles until failure, p = 0.64). INTERPRETATION: Our findings indicate that polymer-reinforcement significantly enhances pedicle screw anchorage in low quality bone and that its effect is similar in size than that of cement augmentation.

Blobbing injury patterns.

INTRODUCTION: "Blobbing" is a modern outdoor activity where a participant sits on the end of a partially inflated air bag ("blobber") and is launched into the water when another participant jumps onto the air bag from a platform on the opposite side ("jumper"). This is the first study to evaluate the injury patterns associated with blobbing. PATIENTS AND METHODS: A retrospective data analysis was conducted based on 86 patients who sustained blobbing injuries between January 2011 and December 2016. The date of birth, gender, day of injury, diagnosis, body region of trauma, and treatment were recorded for the patients. Treatment was subclassified into conservative or surgical treatment. The position of the participant was recorded as either a jumper or a blobber. RESULTS: One-third of the patients sustained a spine injury, which was the most common body part injured. The most frequent type of injury was cervical spine distortion. All shoulder (n = 9), elbow (n = 3), hand (n = 2), knee (n = 3), and foot (n = 12) injuries occurred in jumpers, whereas all ear (n = 6) and lung (n = 5) injuries occurred in blobbers. Head (n = 5) and spine (n = 33) injuries were distributed in jumpers and blobbers. Sixty-nine patients were treated with conservative treatment. Three ankle fractures and two spine fractures were treated with immediate surgical treatment. Twelve patients were treated with conservative treatment but were referred for potential surgery at their hospital at home. CONCLUSION: Both jumpers and blobbers were prone to injuries. More severe injuries with the potential for surgical treatment occurred in jumpers, presumably because of bad landings. This analysis of the injury patterns in blobbers might lead to the introduction of protective gear and changes in the behavior of participants in order to reduce the risk of injury.

Spondylotic traumatic central cord syndrome: a hidden discoligamentous injury?

PURPOSE: To revisit the concept of spondylotic traumatic central cord syndrome (TCCS) by assessing the frequency of discoligamentous injury and to correlate magnetic resonance imaging (MRI) and intraoperative findings. METHODS: A retrospective analysis of twenty-three consecutive patients (mean age: 62.7 ± 14.8 years) with profound spondylotic TCCS after acute cervical hyperextension trauma but without signs of instability on initial CT scans who underwent anterior surgical decompression and fusion was performed. Sensitivity and specificity of MRI in the detection of anterior longitudinal ligament disruption were calculated. The topographic relations between surgically verified segmental instabilities and spinal cord signals on MRI were analyzed. The cervical MRI scans of all patients were evaluated by the radiologist on call at time of admission, re-assessed by a specialized MRI radiologist for the purpose of this study and compared with intraoperative findings. RESULTS: Intraoperative findings revealed 25 cervical spine segments with hyperextension instability in 22 of 23 (95.7%) patients. The radiologist on call correctly assessed segmental hyperextension instability in 15 of 25 segments (sensitivity: 0.60, specificity: 1.00), while the specialized MRI radiologist was correct in 22 segments (sensitivity: 0.88, specificity: 1.00). In 17 of 23 (73.9%) patients, the level of spinal cord signal on MRI matched the level of surgically verified segmental instability. CONCLUSIONS: Our findings challenge the traditional concept of spondylotic TCCS as an incomplete cervical spinal cord injury without discoligamentous injury and emphasize the importance of MRI as well as the radiologist's level of experience for the assessment of segmental instability in these patients. These slides can be retrieved under Electronic Supplementary Material.

Monosegmental anterior column reconstruction using an expandable vertebral body replacement device in combined posterior-anterior stabilization of thoracolumbar burst fractures.

INTRODUCTION: In combined posterior-anterior stabilization of thoracolumbar burst fractures, the expandable vertebral body replacement device (VBRD) is typically placed bisegmentally for anterior column reconstruction (ACR). The aim of this study, however, was to assess feasibility, outcome and potential pitfalls of monosegmental ACR using a VBRD. In addition, clinical and radiological outcome of monosegmental ACR was related to that of bisegmental ACR using the same thoracoscopic technique. METHODS: Thirty-seven consecutive neurologically intact patients with burst fractures of the thoracolumbar junction (T11-L2) treated by combined posterior-anterior stabilization were included. Monosegmental ACR was performed in 18 and bisegmental ACR in 19 patients. Fracture type and extent of vertebral body comminution were determined on preoperative CT scans. Monosegmental and bisegmental kyphosis angles were analyzed preoperatively, postoperatively and at final radiological follow-up. Clinical outcome was assessed after a minimum of 2 years (74 ± 45 months; range 24-154; follow-up rate 89.2%) using VAS Spine Score, RMDQ, ODI and WHOQOL-BREF. RESULTS: Monosegmental ACR resulted in a mean monosegmental and bisegmental surgical correction of - 15.6 ± 7.7° and - 14.7 ± 8.1°, respectively. Postoperative monosegmental and bisegmental loss of correction averaged 2.7 ± 2.7° and 5.2 ± 3.7°, respectively. Two surgical pitfalls of monosegmental ACR were identified: VBRD positioning (1) onto the weak cancellous bone (too far cranially to the inferior endplate of the fractured vertebra) and (2) onto a significantly compromised inferior endplate with at least two (even subtle) fracture lines. Ignoring these pitfalls resulted in VBRD subsidence in five cases. When relating the clinical and radiological outcome of monosegmental ACR to that of bisegmental ACR, no significant differences were found, except for frequency of VBRD subsidence (5 vs. 0, P = 0.02) and bisegmental loss of correction (5.2 ± 3.7° vs. 2.6 ± 2.5°, P = 0.022). After exclusion of cases with VBRD subsidence, the latter did not reach significance anymore (4.9 ± 4.0° vs. 2.6 ± 2.5°, P = 0.084). CONCLUSIONS: This study indicates that monosegmental ACR using a VBRD is feasible in thoracolumbar burst fractures if the inferior endplate is intact (incomplete burst fractures) or features only a single simple split fracture line (burst-split fractures). If the two identified pitfalls are avoided, monosegmental ACR may be a viable alternative to bisegmental ACR in selected thoracolumbar burst fractures to spare a motion segment and to reduce the distance for bony fusion.