Pre-operative Assessment of Shoulder Pathologies on MRI by a Radiologist and an Orthopaedic Surgeon.

Introduction: Pathologies of the shoulder, i.e. rotator cuff tears and labral injuries are very common. Most patients receive MRI examination prior to surgery. A correct assessment of pathologies is significant for a detailed patient education and planning of surgery. Materials and methods: Sixty-nine patients were identified, who underwent both, a standardised shoulder MRI and following arthroscopic shoulder surgery in our hospital. For this retrospective comparative study, the MRIs were pseudonymised and evaluated separately by an orthopaedic surgeon and a radiologist. A third rater evaluated images and reports of shoulder surgery, which served as positive control. Results of all raters were then compared. The aim was an analysis of agreement rates of diagnostic accuracy of preoperative MRI by a radiologist and an orthopaedic surgeon. Results: The overall agreement with positive control of detecting transmural cuff tears was high (84% and 89%) and lower for partial tears (70-80%). Subscapularis tears were assessed with moderate rates of agreement (60 - 70%) compared to intra-operative findings. Labral pathologies were detected mostly correctly. SLAP lesions and pulley lesions of the LHB were identified with only moderate agreement (66.4% and 57.2%) and had a high inter-rater disagreement. Conclusion: This study demonstrated that tears of the rotator cuff (supraspinatus, infraspinatus) and labral pathologies can be assessed in non-contrast pre-operative shoulder MRI images with a high accuracy. This allows a detailed planning of surgery and aftercare. Pathologies of the subscapularis tendon, SLAP lesions and biceps instabilities are more challenging to detect correctly. There were only small differences between a radiologic and orthopaedic interpretation of the images.

[Minimally invasive cement augmentation of osteoporotic vertebral compression fractures with the new radiofrequency kyphoplasty]. / Minimal-invasive Zementaugmentation von osteoporotischen Wirbelkörperfrakturen mit der neuen Radiofrequenz-Kyphoplastie.

OBJECTIVE: Minimally invasive cement augmentation of painful osteoporotic vertebral compression fractures in elderly patients. INDICATIONS: Painful osteoporotic vertebral compression fractures in elderly patients (> 65 years of age) after conservative therapy failure. Painful aggressive primary tumors of the spine or osteolytic metastases to the spine with high risk of vertebral fracture in the palliative care setting. CONTRAINDICATIONS: General contraindications for surgical interventions. Local soft-tissue infection. Osteomyelitis, discitis or systemic infection. Coagulopathy refractory to treatment or bleeding diathesis. Asymptomatic vertebral compression fractures. Burst of the posterior vertebral column with high degree of spinal canal stenosis. Primary or metastatic spinal tumors with epidural growth. SURGICAL TECHNIQUE: Prone position on a radiolucent operating table. Fluoroscopic localization of the fractured vertebra using two conventional C-arm devices (anteroposterior and lateral views). Fluoroscopic localization of the fractured vertebra using two conventional C-arm devices (anteroposterior and lateral views). An introducer is inserted through a small skin incision into the pedicle under fluoroscopic guidance. To create a site- and size-specific three-dimensional cavity in the center of the fractured vertebra, the navigational VertecoR™ MidLine Osteotome was inserted through the correctly sited introducer and guided fluoroscopically. As the MidLine Osteotome allows angulation of the tip up to 90° by rotating the handle, a cavity over the midline of the vertebral body can mainly be created through one pedicle. The radiofrequency activated cohesive ultrahigh viscosity PMMA cement (ER(2) bone cement) is injected stepwise on demand by remote control under continuous pressure from the hydraulic assembly into the vertebral body. POSTOPERATIVE MANAGEMENT: Bed rest for 6 h postoperatively in supine position. Early mobilization without a corset on the day of surgery. Specific back and abdominal exercises that strengthen the back and abdominal muscles. Pain dependent increase of weight bearing. Continue osteoporosis therapy and start specific drug therapy according to the local guidlines if necessary. RESULTS: In all, 44 patients (29 women, 15 men) with a mean age of 73.5 years with a total of 62 painful osteoporotic vertebral fractures were treated with RF kyphoplasty from May 2009 until July 2010, and followed over a period of 12 months. The mean operating time per patient was 36.2 min, the operating time per vertebra was 25.7 min. All the patients studied experienced an early and persistent significant pain relief even 12 months after therapy (8 ± 1.4 vs. 2.7 ± 1.9) according to the visual analogue pain scale. According to the Oswestry Disability Index (ODI) as a disease-specific disability measure all the patients improved significantly (p < 0.001) in the level of disability after operative treatment (56.2 ± 18.8 vs. 34.5 ± 16.6). Cement leakage was detected in 17 out of 62 (27.4 %) augmented vertebrae, whereas all the patients with cement leakage remained asymptomatic. One patient had subsequent vertebral fractures after a period of 6 months.

Dual-energy CT-based assessment of the trabecular bone in vertebrae.

BACKGROUND: Osteoporosis can cause severe fractures of bone structures. One important indicator for pathology is a lowered bone mineral density (BMD) - conventionally assessed by dual-energy X-ray absorptiometry (DXA). Dual-energy CT (DECT) - being an alternative that is increasingly used in the clinics - allows the computation of the spatial BMD distribution. OBJECTIVES: Using DECT, the trabecular bone of vertebrae is examined. Several analysis methods for revealing the bone density distribution as well as appropriate visualization methods for detecting regions of lowered BMD are needed for computer-assisted diagnosis (CAD) of osteoporosis. The hypothesis that DECT is better suited than DXA for the computation of local BMD is investigated. METHODS: Building on a model of the interaction of X-rays with bone tissue, novel methods for assessing the spatial structure of the trabecular bone are presented. CAD of DECT image data is facilitated by segmenting the regions of interest interactively and with an Active Shape Model, respectively. The barycentric space of fractional volumes is introduced as a novel means for analyzing bone constitution. For 29 cadaver specimens, DECT as well as DXA has been examined. BMD values derived from both modalities are compared to local force measurements. In addition, clinical data from two patients who underwent DECT scanning for a different reason is analyzed retrospectively. RESULTS: A novel automated delineation method for vertebrae has been successfully applied to DECT data sets. It is shown that localized BMD measurements based on DECT show a stronger linear correlation (R² = 0.8242, linear regression) to local force measurements than density values derived from DXA (R² = 0.4815). CONCLUSIONS: DECT based BMD assessment is a method to extend the usage of increasingly acquired DECT image data. The developed DECT based analysis methods in conjunction with the visualization provide more detailed information for both, the radiologist and the orthopedist, compared to standard DXA based analysis.

The quality of applied bone cement depends on the chemical composition of the application system.

UNLABELLED: The exothermal reaction of polymethylmethacrylate leads to an extensive interaction between bone cement and the synthetic material of the application system. This chemical reaction changes the structure of the cement and might generate air inclusions. METHODS AND MATERIALS: Two application systems for bone cement made of polycarbonate (PC) and polypropylene (PP) were evaluated. The application systems were mounted in a testing unit. The testing device injects a defined amount of bone cement with a certain pressure. After the injection procedure a microscopic examination was carried out. RESULTS: There were no differences in the size and the design of the used syringes. Forty procedures were carried out. The time frame for application of the cement was 5 min in the PC group and 9 min in the PP group. There was a remarkable interaction between the plastics and the cement with the appearance of numerous air inclusions in the PC group. Barely any interaction was found in the PP group. CONCLUSION: Application systems made of PP enable a prolonged application time and a reduced number of air inclusions. Further research, especially on a molecular level as well as material tests on the quality of the applied bone cement, should be carried out.

Direct implantation of VX-2 carcinoma: a new rabbit bone model using a three-dimensional matrix as a carrier for the tumor cells.

BACKGROUND: Animal bone models are inevitable for musculoskeletal research. The induction of a local bone tumor is complex and time consuming. In this study a new model is presented using a direct implantation of tumor cells into the bone without a preliminary passaging of the cells. METHODS: A three-dimensional matrix consisting of alginate spheroids and carrying the VX-2 tumor suspension was used for implantation into the bone of 6 female New Zealand white rabbits. X-ray imaging, CT and MRI scans as well as a histological examination were carried out. RESULTS: All rabbits developed local bone tumor in the metaphysis of the femoral leg. Bone tumor was identifiable on average 6.2 weeks after implantation. Fluoroscopy, CT and MRI scans showed a cortical reaction but no destruction of the compact bone together with a mean tumor size of 14 mm. Histological examination revealed a tumor infiltration with an activation of osteoclasts and an osteoclastic resorption. CONCLUSION: The direct implantation of a VX-2 tumor suspension into the rabbit bone using alginate spheroids is an effective and reproducible way to successfully induce bone tumor. This new animal model allows further examination of surgical and minimal invasive therapy in musculoskeletal research.

Functional results after giant cell tumor operation near knee joint and the cement radiolucent zone as indicator of recurrence.

BACKGROUND: Giant cell tumor of bone near the knee joints is a dilemma for the operating surgeon. Curettage and bone grafting have a high recurrence, whereas wide resection has a reduced recurrence rate with the compromise of limb function. MATERIALS AND METHODS: Thirty-eight patients with histologically proven giant cell tumor near the knee joint were treated. All patients were reviewed with regard to the operative method, recurrence rate, postoperative arthritis and functional results of the joint. In cases of cement filling, the radiolucent zone and the sclerotic rim were assessed as possible markers for recurrence. RESULTS: 14 male and 24 female patients were included in this study (mean age 28 years, range 13-56 years). All patients underwent surgery, 21 patients were treated with a bone cement filling and additional osteosynthesis after curettage. Seventeen patients were filled with cancellous bone or curettage alone. In the group with bone cement filling after curettage, the recurrence rate was 23.8%, whereas a recurrence rate of 52.9% was detected in the group with cancellous bone filling or curettage alone. The average time to recurrence was two years (5 months to 6 years). An increase of the radiolucent zone was seen in 80% of all patients with a recurrence. CONCLUSION: Cement filling after extensive curettage does not increase the recurrence rate and does not induce osteoarthritis, as long as the continuity of articular cartilage is maintained. Patients with giant cell tumor of bone near the knee joint can be treated satisfactorily with intralesional resection and bone cement packing. The extension of the radiolucent zone after bone cement filling is a reliable indicator for a possible local recurrence.

[Sintering prophylaxis of a vertebral body replacement: anterior cement augmentation of vertebral end plates]. / Sinterungsprophylaxe eines Wirbelkörperersatzes : Anteriore Zementaugmentation von Wirbelkörperendplatten.

Due to the increasing number of elderly patients with osteoporosis, the incidence of more complex operations demanding a vertebral body replacement is increasing in this population. Cement augmentation of pedicle screws helps to prevent screw pullout. Similarly it is possible to augment the end plates in anterior spine surgery in order to prevent cage subsidence. The technique is simple, quick and safe, as needles can be placed under visual control. In a series of 20 patients neither surgery-related complications nor aseptic loosening were found.

[Cement distribution in vertebroplasty pedicle screws with different designs]. / Zementverteilung bei Vertebroplastieschrauben unterschiedlichen Designs.

The effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.

Effect of lumbar disc replacement on the height of the disc space and the geometry of the facet joints: a cadaver study.

In a study on ten fresh human cadavers we examined the change in the height of the intervertebral disc space, the angle of lordosis and the geometry of the facet joints after insertion of intervertebral total disc replacements. SB III Charité prostheses were inserted at L3-4, L4-5, and L5-S1. The changes studied were measured using computer navigation software applied to CT scans before and after instrumentation. After disc replacement the mean lumbar disc height was doubled (p < 0.001). The mean angle of lordosis and the facet joint space increased by a statistically significant extent (p < 0.005 and p = 0.006, respectively). By contrast, the mean facet joint overlap was significantly reduced (p < 0.001). Our study indicates that the increase in the intervertebral disc height after disc replacement changes the geometry at the facet joints. This may have clinical relevance.

Reduction of radiation dose during facet joint injection using the new image guidance system SabreSource: a prospective study in 60 patients.

Interventional procedures are associated with high radiation doses for both patients and surgeons. To reduce the risk from ionizing radiation, it is essential to minimize radiation dose. This prospective study was performed to evaluate the effectiveness in reducing radiation dose during facet joint injection in the lumbar spine and to evaluate the feasibility and possibilities of the new real time image guidance system SabreSource. A total of 60 patients, treated with a standardized injection therapy of the facet joints L4-L5 or L5-S1, were included in this study. A total of 30 patients were treated by fluoroscopy guidance alone, the following 30 patients were treated using the new SabreSource system. Thus a total of 120 injections to the facet joints were performed. Pain, according to the visual analogue scale (VAS), was documented before and 6 h after the intervention. Radiation dose, time of radiation and the number of exposures needed to place the needle were recorded. No significant differences concerning age (mean age 60.5 years, range 51-69), body mass index (mean BMI 26.2, range 22.2-29.9) and preoperative pain (VAS 7.9, range 6-10) were found between the two groups. There was no difference in pain reduction between the two groups (60 vs. 61.5%; P = 0.001) but the radiation dose was significantly smaller with the new SabreSource system (reduction of radiation dose 32.7%, P = 0.01; reduction of mean entrance surface dose 32.3%, P = 0.01). The SabreSource System significantly reduced the radiation dose received during the injection therapy of the lumbar facet joints. With minimal effort for the setup at the beginning of a session, the system is easy to handle and can be helpful for other injection therapies (e.g. nerve root block therapies).

[Contrast-enhanced diagnostics in orthopaedics]. / Kontrastmittelgestützte Diagnostik in der Orthopädie.

The diagnostic competence of the orthopaedist not only allows him to perform adequate therapy concepts, but also to meet the current structural challenges, both social and health related. In addition to clinical diagnosis, machine-aided diagnosis is becoming more important due to technical advances. In this context, contrast-enhanced examination has a special place, as it has an important diagnostic advantage in difficult or unclear cases. Current improvements in the areas of phlebography, myelography, arthrography and angiography are reviewed. Indications, risks and complications as well as the technical procedure are critically discussed.