Improved extraction torque of hydroxyapatite-coated pedicle screws

Sandén, Bengt; Olerud, Claes; Johansson, Carina B.; Larsson, Sune

doi:10.1007/s005860000180

Cited by 38 publications

(26 citation statements)

References 7 publications

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“…Different commercially available plasma-sprayed HA coatings may exhibit different mechanical and histologic characteristics [6]. In a previous clinical study, we found a substantial increase in removal torque of pedicle screws coated with plasmasprayed HA [25]. The same manufacturer that did the coating of the screws in the present study applied the coating of the screws in that study.…”

Section: Discussionmentioning

confidence: 61%

“…Several researchers have tried to find a correlation between pull-out strength and maximum torque for pedicle screws; however, the results have given a mixed outcome, with some studies reporting a good agreement Energy to failure (average±SEM), defined as the area under the load-displacement curve to the maximum load, for HA-coated and uncoated pedicle screws when subjected to pull-out load at different time points following insertion in sheep vertebrae (* indicates a statistically significant difference) [5,37] and others finding no significant agreement between the two loading modes [14,21]. In an earlier clinical study of HA-coated pedicle screws, a marked increase of removal torque was seen when compared to conventional uncoated screws [25]. In the present animal study it therefore seemed important to study the effects of HAcoating on the pull-out strength.…”

Section: Discussionmentioning

confidence: 99%

“…The effects of HA coating on pull-out strength of loaded pedicle screws have not previously been described. As, in a previous clinical study, the present authors measured a significant enhancement of extraction torque when using HA-coated [25] pedicle screws, we considered it important to examine the effects on pull-out resistance when using the same type of HA coating. The sheep spine has been described as a valid biomechanical model for the human spine, and also as an alternative when evaluating spinal implants [32].…”

Section: Bengt Sandén Claes Olerud Sune Larssonmentioning

confidence: 99%

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Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep

2001

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Section: Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Bengt Sandén Claes Olerud Sune Larssonmentioning

confidence: 99%

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Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep

2001

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“…The material composition of the screws and coating has been previously analysed. 17 The diameter of the screws was 6 mm and the length between 55 and 77 mm. Partial or total laminectomy was undertaken in all patients except two, and both of these were in the partlycoated group.…”

Section: Methodsmentioning

confidence: 99%

“…15,16 Coating of stainlesssteel pedicle screws with HA has been used in a clinical study, with a significantly increased torque of the screws on removal. 17 Extraction data were available from four patients only, however, and the design of the pilot study with two HA-coated and two uncoated screws at each instrumentation did not address the question as to whether HA coating improves the purchase of all screws. There were also difficulties in extracting the HA-coated screws.…”

mentioning

confidence: 99%

Hydroxyapatite coating improves fixation of pedicle screws

Sandén¹,

Olerud²,

Petrén-Mallmin

et al. 2002

The Journal of Bone and Joint Surgery. British volume

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We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws.At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 ± 36 Ncm for the uncoated group, 447 ± 114 Ncm for the partly-coated group and 574 ± 52 Ncm for the fully-coated group. There were significant differences between all three groups (p < 0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p < 0.001). HA coating of pedicle screws resulted in improved fixation with reduced risk of loosening of the screws. J Bone Joint Surg [Br] 2002;84-B:387-91.

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Biomechanical and antibacterial properties of Tobramycin loaded hydroxyapatite coated fixation pins

et al. 2014

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The present study investigates the use of nanoporous, biomimetic hydroxyapatite (HA) coatings deposited on TiO₂ coated fixation pins as functional implant surfaces for the local release of Tobramycin in order to prevent bacterial colonization. The impact of HA-coating thickness, coating morphology and biomechanical forces during insertion into synthetic bone on the drug loading and release properties are analyzed. The coatings are shown to exhibit bactericidal effects against Staphylococcus aureus in agar medium for a duration of 6 days after loading by adsorption with Tobramycin for only 5 min at elevated temperature and pressure. Furthermore, high performance liquid chromatography analysis shows a drug release in phosphate buffered saline for 8 days with antibiotic concentration remaining above the minimal inhibitory concentration for S. aureus during the entire release period. Biomechanical insertion tests into synthetic bone and conventional scratch testing demonstrate adhesive strength at the HA/TiO₂ interface. Biocompatibility is verified by cell viability tests. Outgrowth endothelial cells, as well as primary osteoblasts, are viable and firmly attached to both HA and TiO₂ surfaces. The results presented are encouraging and support the concept of functional HA coatings as local drug delivery vehicles for biomedical applications to treat as well as to prevent post-surgical infections.

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Improved extraction torque of hydroxyapatite-coated pedicle screws

Cited by 38 publications

References 7 publications

Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep

Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep

Hydroxyapatite coating improves fixation of pedicle screws

Biomechanical and antibacterial properties of Tobramycin loaded hydroxyapatite coated fixation pins

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