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Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_13 | Pages 140 - 140
1 Nov 2021
Reifenrath J Kempfert M Kampmann A Angrisani N Glasmacher B Menzel H Welke B Willbold E
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Introduction and Objective

In the elderly population, chronic rotator cuff tears are often associated with high re-rupture rates after surgical tendon refixation. Implant materials, especially in combination with additives are supposed to positively influence healing outcome. Furthermore, adequate mechanical properties are crucial. In order to realize degradable implants with high specific surface area, polycaprolactone (PCL) was chosen as basic material and processed by electrospinning to achieve a high surface area for growth factor implementation and subsequent cell attachment.

Materials and Methods

PCL (Mn approx. 80,000 g/mol) was used to generate fibre mats by electrospinning (relative collector velocity 8 m/s; flow rate of 4 ml/h). Mechanical analysis was performed according to EN ISO 527–2:2012 with test specimen 1BA (5 mm in diameter). Maximum force at failure (Fmax) as well as stiffness were evaluated. For preclinical in vivo testing, a coating with CS-g-PCL was performed to increase cellular adhesion and biological integration. Native and TGF-ß3 loaded mats were examined in a chronic rat tendon defect model with dissection of the M. infraspinatus, four week latency and following refixation at the humerus with different PCL-fibre mats (approval Nr. 33.12–42502–04–15/2015). After 8 weeks, rats were finalized and tendon-bone insertions were analyzed biomechanically and via histological methods.


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_I | Pages 32 - 33
1 Mar 2006
Thorey F Witte F Nellesen J Griep-Raming N Menzel H Gross G Hoffmann A Windhagen H
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Introduction: Despite advances in endoprosthesis fixation by implant surface alteration, the problem of aseptic implant loosening still exists. Especially in patients with revisions osseointegration and filling of gaps at the bone-implant interface is mandatory for implant survival. Simple BMP-2 immersion has been introduced previously to act as an osteoinductive coating for advanced osseointegration. However, because of the uncontrolled release kinetics and subsequent molecular action and activity of BMP-2, purely osteoinductive actions are hard to differentiate from osteoclastic BMP-actions leading to bone remodelling, which could counteract the implant fixation process and might be the reason for failed attempts to use BMP-2 for implant fixation. In this study we investigated the osteoinductive potency of BMP-2 bound to titanium surfaces by a highly controlled molecular coupling with specifically designed polymers, allowing a slow controlles release kinetics. We present the first results of two different polymers that were implanted in the tibia and femora of New Zealand White Rabbits.

Methods: In this study we designed cylindrical titanium-implants with an inner thread (Ti6-Alï·& #8220;4V, 3 mm hight x 3 mm diameter) and an electropolished outer surface that were coated with different polymers. The polymers were fixed to the surface using the photochemical method of grafting. The implants were implanted in the proximal tibia and distal femora of New Zealand White Rabbits. The anatomical locations of the implants were alternated to test their osseointegration in different quality of bone (cancellous vs. cortical bone). After 4 weeks the animals were sacrificed and DEXA-scans (Dual-energy X-ray absorptiometry), micro-CT and histological analysis were performed. ANOVA and t-test were used for statistic analysis.

Results: In high-resolution DEXA-scans we found a difference in bone mineral density (BMD) between PVBP and a control implant in the distal femora (PVBP 0,720 g/cm², control 0,661 g/cm²) and in the proximal tibia (PVBP 0,633 g/cm², control 0,431 g/cm²) with an increase of bone mineral density. In the histological investigation we found an increase of osteoblasts around the implants coated with PVBP and PVBP-Co-Acryloxysuccimid. Furthermore, the micro-CT scans showed an increase of BV/TV (bone volume/total volume) for both polymers.

Discussion: In this study we present the first results of the investigation of polymer-coated titanium-implants implanted in the proximal tibia and distal femora of New Zealand White Rabbits. The results of DEXA-scans, micro-CT and histological analysis showed an increase of osseointegration. We suggest that controlled release kinetics after coupling of these polymers with BMP-2 can additionally increase osseointegration. To get a closer look on the polymers, their characteristics in-vivo, and coupling with BMP-2 further investigations are conducted.