Spine imaging after lumbar disc replacement: pitfalls and current recommendations

<p>Abstract</p> <p>Background</p> <p>Most lumbar artificial discs are still composed of stainless steel alloys, which prevents adequate postoperative diagnostic imaging of the operated region when using magnetic resonance imaging (MRI). Thus patients with postoperative radicular symptoms or claudication after stainless steel implants often require alternative diagnostic procedures.</p> <p>Methods</p> <p>Possible complications of lumbar total disc replacement (TDR) are reviewed from the available literature and imaging recommendations given with regard to implant type. Two illustrative cases are presented in figures.</p> <p>Results</p> <p>Access-related complications, infections, implant wear, loosening or fracture, polyethylene inlay dislodgement, facet joint hypertrophy, central stenosis, and ankylosis of the operated segment can be visualised both in titanium and stainless steel implants, but require different imaging modalities due to magnetic artifacts in MRI.</p> <p>Conclusion</p> <p>Alternative radiographic procedures should be considered when evaluating patients following TDR. Postoperative complications following lumbar TDR including spinal stenosis causing radiculopathy and implant loosening can be visualised by myelography and radionucleotide techniques as an adjunct to plain film radiographs. Even in the presence of massive stainless steel TDR implants lumbar radicular stenosis and implant loosening can be visualised if myelography and radionuclide techniques are applied.</p

Insertion torque is not a good predictor of pedicle screw loosening after spinal instrumentation: a prospective study in 8 patients

<p>Abstract</p> <p>Background</p> <p>Pedicle screw loosening is a major safety concern in instrumented spinal surgery due to loosening with potential pseudarthrosis and possible loss of correction requiring revision surgery. Several cadaver studies have compared insertion torque of pedicle screws with resistance to pullout or cyclic loading. In most of these studies, a correlation has been found between these variables. Clinical studies have been made, comparing insertion torque to bone mineral density or radiological signs of screw loosening. There are no clinical studies comparing insertion torque to extraction torque or other biomechanical parameters in vivo. This study was designed to investigate whether the insertion torque of pedicle screws can be used to predict the purchase of the screws.</p> <p>Methods</p> <p>The insertion torque of stainless steel pedicle screws was recorded in eight patients undergoing lumbar fusion surgery with four-screw constructs. Torque gauge manometers were used for the recordings. The implants were removed after one year, and the extraction torque of the screws was recorded.</p> <p>Results</p> <p>The mean insertion torque was 76 ± 41 Ncm and the mean extraction torque 29 ± 36 Ncm. The r value was 0.591, suggesting that there was a correlation between the insertion and extraction torque. However, the scattergram revealed that the screws could be divided into two groups, six screws with a high correlation between insertion and extraction torque, and 26 screws where no correlation could be demonstrated.</p> <p>Conclusions</p> <p>In this unique human in-vivo study, the insertion torque could not be used to predict the purchase of lumbar pedicle screws one year after implantation. It could be demonstrated that in vivo insertion torque alone is of minor value to estimate pullout strength, and should be combined with or replaced by more accurate measures.</p

Swespine: the Swedish spine register : The 2012 report.

Swespine, the Swedish National Spine Register, has existed for 20 years and is in general use within the country since over 10 years regarding degenerative lumbar spine disorders. Today there are protocols for registering all disorders of the entire spinal column

Fixation of Spinal Implants : Clinical and Experimental Studies on the Effects of Hydroxyapatite Coating

Loosening of implants is a frequent complication in orthopaedic surgery. The aim of this thesis was to evaluate hydroxyapatite coating of pedicle screws with mechanical and histological methods and to correlate the results with the radiological findings. Hydroxyapatite (HA) coating of pedicle screws was investigated in experimental studies in sheep. Nine sheep were operated on with destabilising laminectomies at L2-L3 and L4-L5 and stabilised with pedicle screw instrumentations, where HA coated and uncoated screws were used in a randomised fashion. After both 6 and 12 weeks of implantation, the HA coated screws demonstrated a higher bone-to-implant contact and a higher amount of bone in the area close to the screw. The pull-out resistance, stiffness and total energy to failure was higher for the HA coated screws after 12 weeks of implantation. HA coating of pedicle screws was examined in two clinical studies. In the first series, the patients were stabilised with pedicle screw instrumentations, where HA coated screws were used in either the upper or lower instrumented level in a randomised fashion. After 10-22 months of implantation, the extraction torque was markedly higher for the HA coated screws. In the second series, instrumentations with uncoated, partly HA coated or fully HA coated screws were used. After 11-16 months implantation, the extraction torques were recorded. There were significant differences between all three groups, with the lowest extraction torques for the uncoated screws and the highest torques for the fully HA coated screws. The frequency of radiolucent zones surrounding the screws was higher for the uncoated screws than for the HA coated screws. Radiographs from both experimental and clinical studies were examined. Screws demonstrating radiolucent zones were compared to screws without zones with respect to pull-out resistance, extraction torque, bone-to-implant contact and amount of bone surrounding the screws. All these variables demonstrated higher values for the screws without radiolucent zones. The frequency of radiolucent zones surrounding uncoated screws in the clinical study was 53%. Conclusions: Radiolucent zones are good predictors of screw loosening. The frequency of radiolucent zones is higher than previously described. Hydroxyapatite coating improves the purchase of pedicle screws and reduces the frequency of screw loosening

Radiographic results after plaster cast fixation for 10 days versus 1 month in reduced distal radius fractures : a prospective randomised study

BACKGROUND: The aim of this study was to examine whether reduced distal radius fractures can be treated with early mobilisation without affecting the radiographic results. METHODS: In a prospective randomised study, 109 patients (mean age 65.8 (range 50-92)) with moderately displaced distal radius fractures were treated with closed reduction and plaster cast fixation for about 10 days (range 8-13 days) followed by randomisation to one of two groups: early mobilisation (n = 54, active group) or continued plaster cast fixation for another 3 weeks (n = 55, control group). RESULTS: For three patients in the active group (6%), treatment proved unsuccessful because of severe displacement of the fracture (n = 2) or perceived instability (n = 1). From 10 days to 1 month, i.e. the only period when the treatment differed between the two groups, the active group displaced significantly more in dorsal angulation (4.5°, p &lt; 0.001), radial angulation (2.0°, p &lt; 0.001) and axial compression (0.5 mm, p = 0.01) compared with the control group. However, during the entire study period (i.e. from admission to 12 months), the active group displaced significantly more than the controls only in radial angulation (3.2°, p = 0.002) and axial compression (0.7 mm, p = 0.02). CONCLUSIONS: Early mobilisation 10 days after reduction of moderately displaced distal radius fractures resulted in both an increased number of treatment failures and increased displacement in radial angulation and axial compression as compared with the control group. Mobilisation 10 days after reduction cannot be recommended for the routine treatment of reduced distal radius fractures. TRIAL REGISTRATION: ClinicalTrail.gov, NCT02798614 . Retrospectively registered 16 June 2016

Prospective randomized feasibility trial to assess the use of rhPDGF-BB in treatment of distal radius fractures

BACKGROUND: Recombinant human platelet-derived growth factor BB (rhPDGF-BB) combined with an osteoconductive scaffold (β-TCP) has been demonstrated to increase bone formation, but rhPDGF-BB has not been studied in human fractures. The purpose of this study was to evaluate the safety and potential use of locally administered rhPDGF-BB/β-TCP (Augment®) in acute wrist fractures. METHODS: Forty patients with unstable distal radial fracture were randomized to closed reduction and external fixation alone (n = 20) or combined with injection of rhPDGF-BB/β-TCP (Augment®) into the fracture (n = 20). All patients were followed for 24 weeks. Outcome was based on adverse events, fracture displacement on radiographs, fracture healing, range of motion, grip strength, pain, and the disability of the arm, shoulder and hand (DASH) score. RESULTS: There were no serious adverse events in the study, but the pin tract infection rate was significantly lower in the Augment® group. There was no difference between the groups in fracture healing time, based on number of healed cortices or fracture displacement. The Augment® group had an early temporary significant decrease in wrist flexion, but no difference in range of motion at 24 weeks. There were no differences between the two treatment groups for any other outcome variables. CONCLUSION: rhPDGF-BB/β-TCP (Augment®) is safe and convenient for local administration into wrist fractures. In this pilot study, we could not detect any reduced healing time in the Augment® group although potential efficacy should be addressed in larger studies. CLINICAL TRIAL REGISTRATION NUMBER: The clinical trial registration number for the study protocol is BMPI-2014-02-E

Prospective randomized feasibility trial to assess the use of rhPDGF-BB in treatment of distal radius fractures

BACKGROUND: Recombinant human platelet-derived growth factor BB (rhPDGF-BB) combined with an osteoconductive scaffold (β-TCP) has been demonstrated to increase bone formation, but rhPDGF-BB has not been studied in human fractures. The purpose of this study was to evaluate the safety and potential use of locally administered rhPDGF-BB/β-TCP (Augment®) in acute wrist fractures. METHODS: Forty patients with unstable distal radial fracture were randomized to closed reduction and external fixation alone (n = 20) or combined with injection of rhPDGF-BB/β-TCP (Augment®) into the fracture (n = 20). All patients were followed for 24 weeks. Outcome was based on adverse events, fracture displacement on radiographs, fracture healing, range of motion, grip strength, pain, and the disability of the arm, shoulder and hand (DASH) score. RESULTS: There were no serious adverse events in the study, but the pin tract infection rate was significantly lower in the Augment® group. There was no difference between the groups in fracture healing time, based on number of healed cortices or fracture displacement. The Augment® group had an early temporary significant decrease in wrist flexion, but no difference in range of motion at 24 weeks. There were no differences between the two treatment groups for any other outcome variables. CONCLUSION: rhPDGF-BB/β-TCP (Augment®) is safe and convenient for local administration into wrist fractures. In this pilot study, we could not detect any reduced healing time in the Augment® group although potential efficacy should be addressed in larger studies. CLINICAL TRIAL REGISTRATION NUMBER: The clinical trial registration number for the study protocol is BMPI-2014-02-E

Development of a wide-covearge interlingual computational lexicon in Grammatical Framework

Darbā tiek skatīts kā varētu veidot starpvalodu leksikonu latviešu valodai Grammatical Framework ietvarā. Pašlaik ietvarā jau ir ieviests pamata latviešu valodas atbalsts ar kura palīdzību var novērtēt tā funkcionalitāti. Tomēr nav pieejams pietiekami plašs leksikons morfoloģiskas analīzes un tulkošanas iespēju attīstīšanai un novērtēšanai. Šī darba ietvaros izstrādāts starpvalodu skaitļojamais leksikons latviešu valodai lietošanai Grammatical Framework ietvarā un aprakstīti tā veidošanas principi. Tas nodrošina aptuveni 60 tūkstoši leksēmu priekš valodas un vairāk kā 10 tūkstošu vārdu sasaisti ar abstrakto valodu tulkošanas vajadzībām.In this work, we are exploring ways in which to develop interlingual lexicon for use in Grammatical Framework. Currently basic Latvian language support has been implemented in framework that can be used to assess provided functionality. However, a sufficiently wide coverage lexicon for improvement and assessment of morphological analysis and translation is not available. This work involved developing interlingual computational lexicon for Latvian language to be used in Grammatical Framework, and describes the principles of its formation. It provides some 60 thousand lexemes for Latvian language and linked more than 10 thousand words with the abstract language for translation purposes