Which anatomic structures are responsible for the reduction loss after hybrid stabilization of osteoporotic fractures of the thoracolumbar spine?

INTRODUCTION: Hybrid stabilization is an accepted therapy strategy for unstable osteoporotic thoracolumbar fractures. However, a moderate reduction loss has been reported and it remains unclear which anatomic structure is responsible for the reduction loss. METHODS: This retrospective study was performed at a level I trauma center. Patients aged 61 and older were stabilized using hybrid stabilization after suffering acute and unstable osteoporotic vertebral body fractures at the thoracolumbar spine. Posterior stabilization was done short-segmental and minimal invasive with cement-augmentation of all pedicle screws. The minimum follow-up has been 2 years. The outcome parameters were the reduction loss and the relative loss of height of both intervertebral discs adjacent to the fractured vertebral body, the fractured vertebral body and a reference disc (intervertebral disc superior of the stabilization) between the postoperative and latest lateral radiographs. Additionally, implant positioning and loosening was analyzed. RESULTS: 29 mainly female (72%) patients (73.3 ± 6.0 years) were included. Fractures consisted of 26 incomplete burst fractures and 3 complete burst fractures of the thoracolumbar junction (Th11 - L2: 86%) and the midlumbar spine. The mean follow-up time was 36 months (range: 24-58 months). The mean reduction loss was 7.7° (range: 1-25). The relative loss of heights of both intervertebral discs adjacent to the fractured vertebral body, the reference disc, and the central vertebral body were significant. Thereby, the relative loss of the superior disc height was significant higher compared to the reference disc. Additionally, only the relative loss of central vertebral body height and reduction loss correlated significantly. There were no signs of implant loosening in any patient. CONCLUSIONS: The mean reduction loss was moderate 3 years after hybrid stabilization of unstable osteoporotic vertebral fractures of the thoracolumbar spine. A significant loss of both adjacent disc heights and the central vertebral body was seen, with the highest loss in the superior adjacent disc significantly outranging the reference disc. The superior adjacent intervertebral disc and the central part of the fractured vertebral body seem to be responsible for the majority of reduction loss.

[Which factors influence the inpatient course for patients with spondylodiscitis?] / Welche Parameter haben Einfluss auf den stationären Verlauf bei Patienten mit Spondylodiszitis?

BACKGROUND: Spondylodiscitis is a rare disease with an increasing incidence. METHODS: In this retrospective study 112 patients with spondylodiscitis surgically treated from 1 January 2005 to 31 December 2012 in a level I spine center were investigated with respect to potential prognostic criteria. The time period covered by the investigation was the duration of hospitalization. The parameters analyzed were mortality, age, localization of the spondylodiscitis, detection of abscesses and pathogens, neurological status and body mass index (BMI). RESULTS: The average age of the patients was 68.3 years (±12.9 years). The mortality rate during hospitalization was 10.7% (N = 12). Older patients had a significantly higher in-hospital mortality rate (p = 0.008). Abscess formation was found in 49.1% of the patients and was associated with a significantly longer hospital stay (p = 0.001) and in the intensive care unit (ICU, p = 0.001) as well as a higher risk of revision surgery (p = 0.018). In addition, obese patients had a significantly higher occurrence of abscesses (p = 0.034). Pathogen detection was successful in 60.7 % of the cases with Staphylococcus aureus as the most frequent pathogen. Detection of pathogens was associated with a longer hospital stay (p = 0.006) and a greater need of intensive care monitoring (p = 0.017). Patients with a nephropathy had a significantly increased mortality, longer duration of hospitalization and a more frequent occurrence of multilevel afflictions. CONCLUSION: Old age, abscess formation, positive detection of pathogens and renal failure can be used as prognostic criteria. Risk factors for formation of abscesses include a lumbar localization of spondylodiscitis, nephropathy as well as detection of a pathogen and obesity.

Odontoid fractures in combination with C1 fractures in the elderly treated by combined anterior odontoid and transarticular C1/2 screw fixation.

INTRODUCTION: The purpose of this study was to evaluate risk factors of accompanied C1 fractures in elderly patients with type II odontoid fractures (OF) and to analyze the complication rate and the outcomes of patients after combined anterior odontoid and transarticular C1/2 screw fixation (AOTAF). MATERIALS AND METHODS: The study represents a retrospective case series at a single level-1 trauma center. All elderly patients (≥ 70 years) with acute combination injuries (CI) including type II OF with an accompanied C1 fracture, who were treated by an anterior approach, were included. All postoperative complications were analyzed based on the patient notes. Clinical and radiological controls were performed after 1 year. Main parameters of interest were 1-year mortality rate, pain level, and satisfaction rate after 1 year. RESULTS: A total of 23 patients were included. The average age was 84.6 years (range 73-94 years). All patients had atlanto-odontoid osteoarthritis (AOO) and all but two patients were injured by low-energy falls. Dysphagia was the most common postoperative complication (26.1%). Surgical revision was necessary in one of these patients due to hematoma. Dysphagia improved in all patients considerably. Loss of follow-up was 21.7%. The 1-year mortality was 21.7% (n = 5). The mean pain level and satisfaction rate was 2.5 (± 0.9) and 7.3 (± 0.7), respectively. After 1 year, no signs of non-union were visible. CONCLUSIONS: AOO was observed in all patients with CI. The main cause of trauma was a low-energy fall. The pain levels were low to moderate and satisfaction levels were promising 1 year after surgery. Nonetheless, AOTAF is associated with a high rate of postoperative dysphagia, which resolves in the majority of patients due to conservative management.

Anterior transarticular atlantoaxial screw fixation in combination with dens screw fixation for type II odontoid fractures with associated atlanto-odontoid osteoarthritis.

PURPOSE: The purpose of this study was to evaluate the 1-year outcome after anterior transarticular atlantoaxial fixation and odontoid fusion (TAFOF) for type II odontoid fractures and atlanto-odontoid osteoarthritis (AO) in elderly patients. METHODS: All geriatric patients, age 70 or older, with acute traumatic type II odontoid fractures and moderate or severe AO treated by TAFOF were included. The study was performed at a single institution between June 2008 and August 2013. Patients were evaluated clinically and radiologically after 1 year. Main parameter of interest were in-hospital and 1-year mortality rates, complication rates (re-operations, prolonged hospital stay, blood transfusion; non-union), and the patients' pain (0: no pain; 10: maximal pain) and satisfaction level (0: lowest satisfaction; 10: highest satisfaction) after 1 year. RESULTS: A total of 83 patients were included with an average age of 84.7 years (range 70-101 years). 39 patients were subdivided as "old" with an age 70-84 years and 44 patients were defined as "very old" with an age of 85 or higher. The average operation time was 64.7 min. Three patients died during the inpatient stay (3.6 %). Twenty patients (24.1 %) were lost contact follow-up. The 1-year mortality was 25.4 % with a significantly higher mortality rate in very old patient group (p = 0.01). At the 1-year follow-up, the mean pain level was 3.3 and the mean patient satisfaction level was 6.5. Osseous consolidation of the dens was visible in 90.2 % of patients. Revision surgery was performed in three patients (3.6 %). Generally, a significantly higher complication rate was seen after single-screw fixation of the dens compared to a double-screw fixation in combination with TAF (p = 0.042). CONCLUSIONS: Anterior TAFOF leads to promising 1-year results with low in-hospital mortality and a high fusion rate in geriatric patients with type II odontoid fractures and relevant AO. Double-screw dens fixation seems to reduce the complication rate.

Correction: Winkler et al. The Adhesion G-Protein-Coupled Receptor GPR115/ADGRF4 Regulates Epidermal Differentiation and Associates with Cytoskeletal KRT1. Cells 2022, 11, 3151.

In the original publication [...].

The Adhesion G-Protein-Coupled Receptor GPR115/ADGRF4 Regulates Epidermal Differentiation and Associates with Cytoskeletal KRT1.

Among the 33 human adhesion G-protein-coupled receptors (aGPCRs), a unique subfamily of GPCRs, only ADGRF4, encoding GPR115, shows an obvious skin-dominated transcriptomic profile, but its expression and function in skin is largely unknown. Here, we report that GPR115 is present in a small subset of basal and in most suprabasal, noncornified keratinocytes of the stratified epidermis, supporting epidermal transcriptomic data. In psoriatic skin, characterized by hyperproliferation and delayed differentiation, the expression of GPR115 and KRT1/10, the fundamental suprabasal keratin dimer, is delayed. The deletion of ADGRF4 in HaCaT keratinocytes grown in an organotypic mode abrogates KRT1 and reduces keratinocyte stratification, indicating a role of GPR115 in epidermal differentiation. Unexpectedly, endogenous GPR115, which is not glycosylated and is likely not proteolytically processed, localizes intracellularly along KRT1/10-positive keratin filaments in a regular pattern. Our data demonstrate a hitherto unknown function of GPR115 in the regulation of epidermal differentiation and KRT1.

Halo Fixator and Halo Traction - Value for the Treatment of Spinal Disorders in Childhood. / Halofixateur und Halotraktion ­ Stellenwert bei Erkrankungen und Verletzungen der Wirbelsäule im Kindesalter.

The application of the Halo fixateur in case of spinal pathologies in childhood is a standardized technique. The halo fixateur may be used for treatment of injuries of the cervical spine, for additional stabilization following extended surgery at the cervical spine and their transitional regions as well as to achieve preoperative reduction in case of severe and rigid deformity. These indications are, referred to the early age, rare. However, the successful use of the Halo fixateur presumes a certain familiarity with the device and experiences regarding the underlying diseases to minimize related risks and to avoid possible complications. In this article the use and specific features regarding the application of the halo fixateur in childhood based on presented cases and the literature will be discussed.

Spontaneous intraoperative lumbar fracture leading to an unexpected correction in ankylosing spondylitis corrective surgery - a case report.

Severe kyphotic deformity in patients with ankylosing spondylitis can be corrected surgically to achieve a better spinal alignment and an improved visual axis. Different surgical techniques are used today depending on the extent of ossification and the degree of kyphosis. It is well known that the underlying disease leads to distinct biomechanical changes of the spinal column causing an increased fracture risk especially in case of minor trauma. This includes manipulations during surgical procedures as well as during the required perioperative measures. We present the case of a 45-year-old patient with severe global kyphotic deformity due to ankylosing spondylitis. During the elective corrective surgery (pedicle subtraction osteotomy at the level of L3) the patient sustained a spontaneous fracture at L2/3. This fortunately nondisplaced wedge-shaped fracture in the sense of a Smith-Peterson osteotomy led to a spontaneous correction of the kyphosis. The described unexpected event required a change in the surgical strategy. Correction could be achieved using a two-stage surgical procedure without further drawbacks for the patient. This case report stresses the need of particular attention regarding the increased susceptibility of the spinal column in case of ankylosing spondylitis.

Revision characteristics of cement-augmented, cannulated-fenestrated pedicle screws in the osteoporotic vertebral body: a biomechanical in vitro investigation. Technical note.

In generalized osteoporosis, instrumentation with cement-augmented pedicle screws is an amplification of the therapeutic spectrum. Early clinical results are promising for both solid and cannulated screws; however, there are concerns regarding the revision characteristics of these screws, especially for the cannulated-fenestrated type with its continuous cement interconnection from the core of the screw to surrounding bone tissue. In a human cadaver model, bone mineral density (BMD) was assessed radiographically. Spinal levels T9-L4 were instrumented left unilaterally, transpedicularly by using cannulated-fenestrated pedicle screws with the dimensions 6.5 x 45 mm. Polymethylmethacrylate cement (1.5 ml) was injected through the screws into each vertebra. After polymerization of the cement, the extraction torque was recorded. For both implantation and explantation of the screws, a fluoroscope was used to guarantee correct screw and cement positioning and to observe possible co-movements-that is, any movement of the cement mass within the vertebral body upon removal of the screw. For comparison, the extraction torque of same-dimension pedicle screws was recorded in a nonosteoporotic, non-cement-augmented instrumentation. The BMD was 0.60 g/cm2, a level that corresponds to a severe grade of osteoporosis. For removal of the screws, the median and mean extraction torques were 34 and 49 +/- 44 Ncm, respectively. No co-movements of the cement mass occurred within the vertebral body. In the nonosteoporotic control, BMD was 1.38 g/cm2. The median and mean extraction torques were 123 and 124 +/- 12 Ncm, respectively. Thus, the revision characteristics of cement-augmented, cannulated-fenestrated pedicle screws are not problematic, even in cases of severe osteoporosis. The winglike cement interconnection between the screw core and surrounding bone tissue is fragile enough to break off in the event of an extraction torque and to release the screw. There is no proof to support the theoretical fear that while trying to remove a screw, the composite of screw and cement would not break but instead would rotate as a whole in the osteoporotic vertebral body.

Vertebral Artery Caught in the Fracture Gap after Traumatic C2/3 Spondylolisthesis.

BACKGROUND CONTEXT: Patient with a C2 fracture and entrapment of the right vertebral artery in the fracture gap. PURPOSE: Presentation of a case with follow-up until end of treatment. STUDY DESIGN: Case report. METHODS: A 25-year-old woman was brought into our emergency room after falling while riding a horse. She complained of pain in the cervical spine. Clinical examinations showed local tenderness at the upper cervical spine and painful impairment of the mobility of the neck, with no signs of neurological impairment. Radiological diagnostics revealed a traumatic C2/3 spondylolisthesis. A computer tomography (CT) angiographic scan showed a dislocation of the right vertebral artery into the fracture gap without injury to the artery. Open reduction and osteosynthesis were considered of too high risk. Therefore, we conducted fracture treatment with closed reduction and halo fixation. After removal of the halo fixator, the patient was given a soft cervical collar and was advised to rest for additional 6 weeks before beginning gradual activity. RESULTS: Conventional follow-up revealed osseous consolidation and a CT angiographic scan showed consistent blood flow to the artery. CONCLUSION: Halo fixation was a safe and effective therapy strategy in the case of vertebral artery entrapment after traumatic C2 spondylolisthesis.

The endoscopically assisted simultaneous posteroanterior reconstruction of the thoracolumbar spine in prone position.

BACKGROUND CONTEXT: The reconstruction of the anterior column of the thoracolumbar spine has become more common in the last few years, due largely to the unfavorable results of exclusively posterior surgical treatment, which has been associated with a lack of about 10 degrees of kyphosis correction after removal of the instrumentation. The minimally invasive anterior techniques have reduced the morbidity of the anterior approach significantly. PURPOSE: A minimally invasive technique for anterior stabilization of the spine may reduce the morbidity of the open approach. Irrespective of an anterior open or an endoscopic approach, the posteroanterior instrumentation of thoracolumbar fractures requires time-consuming intraoperative maneuvers to change the patient position from prone to lateral. We describe here a standardized anterior endoscopically assisted approach for the segments T4 to L4. This approach allows the patient to remain in prone position. A 4- to 5-cm incision combined with a retractor system is used. STUDY DESIGN/SETTING: In a prospective study, all patients of our clinic who underwent surgery of the thoracolumbar spine between July 1999 and May 2001 were registered. Study criteria were duration of surgery, duration of anesthesia, intra- and postoperative complications. PATIENT SAMPLE: Between July 1999 and May 2001, 42 patients (25 male, 17 female, average age of 41.9 years), who presented with 55 injured spinal levels and underwent surgery of the thoracolumbar spine in prone position, were included. OUTCOME MEASURES: Duration of surgery (posterior/anterior/total), duration of anesthesia, method of instrumentation, intra- and postoperative complications, postoperative hospital stay and radiographs were evaluated. METHODS: Surgery was performed in prone position. A thoracic approach was used for instrumentation of T9 to L2. A retroperitoneal approach was used for stabilization of L1 to L5. Both procedures were endoscopically assisted with a new retractor system (Synframe; Synthes GmbH, Umkirch, Germany). In this manner, only an incision 4 to 5 cm long and a stab incision for the endoscope were required. The whole procedure was performed in prone position without a change of position during surgery. RESULTS: A total of 42 patients underwent surgery following this technique: 14 isolated anterior procedures (median duration of surgery, 181 minutes); 13 simultaneous one-stage procedures (median duration of surgery: 210 minutes) and 15 combined two-stage procedures (median duration of surgery: 90 minutes posterior, 120 minutes anterior, 240 minutes posterior+anterior). In the simultaneous posteroanterior procedures, the anterior instrumentation was performed 20 times using one rod, twice using two rods and in six patients simply by bone grafting. No intraoperative complications were observed. In the postoperative course, one case of pneumothorax, one case of hemothorax and one case of transient intercostal neuralgia occurred. CONCLUSION: The approach to the anterior spine in prone position is feasible by using a self-holding retractor system for the region between T4 and L4. The duration of anesthesia for the one-stage simultaneous procedure was reduced by about 40 minutes, because changing the position of the patient is no longer necessary. The minimal incision, in combination with the retractor system, significantly reduces cost by allowing the use of less expensive instruments and implants. The advantages of the open and the endoscopic techniques are combined, while their disadvantages are minimized. The main advantage of the prone position is the opportunity to access the anterior and posterior spine simultaneously, which is especially helpful in reduction maneuvers.

The influence of distraction force on the intradiscal pressure gradient in the bridged lumbar spine: a biomechanical investigation using a calf model.

STUDY DESIGN: A biomechanical calf cadaver study. OBJECTIVE: The purpose of this study was to determine the intradiscal pressure gradient of bridged healthy intervertebral segments in correlation with intraoperative distraction force. SUMMARY OF BACKGROUND DATA: Bisegmental dorsal stabilization and anatomic reduction is a common treatment option for incomplete burst fractures of the lumbar spine. However, it remains unknown to what extent bridging and intraoperative distraction compromises an intact intervertebral disc. METHODS: The L2-L3 intervertebral disc level was evaluated in 6 freshly frozen calf cadaver spines. Pressure measurements were obtained with the spine uninstrumented, after dorsal segmental instrumentation from L1 to L3, and after distraction with 400 N and 800 N. Pressure gradient measurements were accomplished with a balloon pressure sensor placed within the nucleus pulposus of the L2-L3 intervertebral disc. Pressure data were recorded by computer data acquisition. Flexion, extension, and lateral bending moments were applied continuously by a testing machine up to a load moment of 7.5 N·m. The pressure gradients were compared with respect to the effects of added instrumentation and distraction. RESULTS: After segmental bridging the mean pressure gradients were significantly reduced in all movement directions (P < 0.001). However, after dorsal stabilization a continuously rising intervertebral disc pressure was recordable. In contrast, no relevant additional reduction of the intradiscal pressure gradient was detectable after applying distraction forces of 400 N or 800 N. CONCLUSION: In a calf model, a distraction force of up to 800 N leads to no additional reduction of the pressure gradient of bridged healthy lumbar segments under flexion and extension moments.

Skeletal muscle expression of the adhesion-GPCR CD97: CD97 deletion induces an abnormal structure of the sarcoplasmatic reticulum but does not impair skeletal muscle function.

CD97 is a widely expressed adhesion class G-protein-coupled receptor (aGPCR). Here, we investigated the presence of CD97 in normal and malignant human skeletal muscle as well as the ultrastructural and functional consequences of CD97 deficiency in mice. In normal human skeletal muscle, CD97 was expressed at the peripheral sarcolemma of all myofibers, as revealed by immunostaining of tissue sections and surface labeling of single myocytes using flow cytometry. In muscle cross-sections, an intracellular polygonal, honeycomb-like CD97-staining pattern, typical for molecules located in the T-tubule or sarcoplasmatic reticulum (SR), was additionally found. CD97 co-localized with SR Ca2+-ATPase (SERCA), a constituent of the longitudinal SR, but not with the receptors for dihydropyridine (DHPR) or ryanodine (RYR), located in the T-tubule and terminal SR, respectively. Intracellular expression of CD97 was higher in slow-twitch compared to most fast-twitch myofibers. In rhabdomyosarcomas, CD97 was strongly upregulated and in part more N-glycosylated compared to normal skeletal muscle. All tumors were strongly CD97-positive, independent of the underlying histological subtype, suggesting high sensitivity of CD97 for this tumor. Ultrastructural analysis of murine skeletal myofibers confirmed the location of CD97 in the SR. CD97 knock-out mice had a dilated SR, resulting in a partial increase in triad diameter yet not affecting the T-tubule, sarcomeric, and mitochondrial structure. Despite these obvious ultrastructural changes, intracellular Ca2+ release from single myofibers, force generation and fatigability of isolated soleus muscles, and wheel-running capacity of mice were not affected by the lack of CD97. We conclude that CD97 is located in the SR and at the peripheral sarcolemma of human and murine skeletal muscle, where its absence affects the structure of the SR without impairing skeletal muscle function.