Jens-Peter Stahl

Justus-Liebig-Universität Gießen, Gieben, Hesse, Germany

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Publications (10)21.68 Total impact

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    ABSTRACT: The combination of hydroxyapatite (HA) implants serving as osteoconductive scaffold with growth factors is an interesting approach for the improvement of bone defect healing. The purpose of this study was to test whether recombinant human bone morphogenetic protein-2 (rhBMP-2) coating of solid HA-implants improves bone formation in a cortical bone defect. Cylindrical trephine mill defects (diameter: 9.8 mm, depth: 10 mm) were created into the cortical tibia shaft of minipigs and subsequently filled either by plain HA cylinders (Endobon) or by rhBMP-2-coated HA cylinders. Fluorochrome labeling for the evaluation of time-dependent bone formation was done on days 8, 9, and 10 postsurgery with tetracyclin-100, at days 25 and 30 with alizarin-komplexon, and finally on days 32, 37, 73, and 79 with calcein green. Twelve weeks after implantation, the tibiae were harvested and were prepared for standard histological staining, fluorochrome analysis, and histomorphometry. Coating of HA implants with rhBMP-2 led to significant enhanced new bone formation of 84.7% (+/-4.6%) of the implant area with almost complete bony incorporation compared with only 27.7% (+/-8.5%) in the uncoated HA implants (p = 0.028). In both types of implants, osteoconduction of HA led to bone ingrowth of the surrounding host bone into the implants. However, only rhBMP-2-coated implants showed multitopic de novo bone formation reflecting the osteoinductive properties of rhBMP-2 in all areas of the HA implant. This study showed that the coating of HA ceramic implants with rhBMP-2 can significantly enhance new bone formation attributable to its osteoinductive effects.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 12/2008; 90(1):75-81. · 2.31 Impact Factor
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    Ralf Kraus, Jens-Peter Stahl, Reinhard Schnettler
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    ABSTRACT: Treatment concepts in thoracolumbar vertebral fractures include conservative treatment, internal fixator, and vertebral body replacement with implants and autologous bone grafts. The role of biomaterials in these concepts is unclear. Specific properties of biodegradable osteosynthetics seem not to be suitable for an employment in spine surgery. Growth factors may get significant importance in future when the risk of ectopic bone formation in the neurogenic canal is abandoned, particularly in combination with artificial bone substitutes. Bioresorbable bone substitutes are widely in use in vertebro- and kyphoplasty at this time and seem to replace bone cements. In vertebral body replacement they are employed to enlarge the amount of autologous cancellous bone, but not as stand-alone implants. As in many other fields, the use of biomaterials in thoracolumbar spinal injuries will rapidly increase in future.
    European Journal of Trauma 05/2006; 32(3):253-257.
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    ABSTRACT: Different techniques and devices have been used for correction osteotomies of bones in patients with malalignments. The most frequently used technique for rotational deformities of the femur and tibia is open osteotomy with an oscillating saw and pre-drilled holes with all well-known drawbacks of open surgery. An intramedullary device with an adapted minimal-invasive surgical technique allows intramedullary osteotomy of the bone preserving the surrounding soft tissue. We performed femoral osteotomies with an intramedullary saw followed by static interlocking nailing in 14 patients with post-traumatic rotational deformity in the femur. Twelve patients had an external rotational deformity of the femur ranging between 26 and 63 degrees , one had an additional leg-shortening of about 4 cm. Two patients had internal rotational deformities. In two patients with delayed fracture healing union was achieved within one year without secondary surgery. Post-operative clinical assessment and CT-scans revealed good derotation results with deformities of less than 4 degrees in all cases. No device-related complications were observed. Therefore, we conclude that "closed" osteotomy with an intramedullary saw is a minimal-invasive, safe and reliable option for derotation procedures in the femur.
    Injury 03/2006; 37(2):145-51. · 1.93 Impact Factor
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    ABSTRACT: Glycerol-l-lactide as coating polymer for the delivery of basic fibroblast growth factor (bFGF) from hydroxyapatite (HA) ceramic implants was shown to lead to significant delay in bone ingrowth into the implants compared to implants without the coating polymer. The purpose of this work was to study bone ingrowth in HA ceramic implants with and without the coating polymer but without growth factors to enable differentiation between a locking effect of the pores by the polymer and the fact of inactivation of the growth factors by the polymer, which could both be possible for the delay. A defect was created in the subchondral region of both femurs in 24 miniature-pigs and was either filled by the HA implants with or without the coating polymer. Histomorphometry showed a significant delay in bone ingrowth in the polymer coated implants both after 6 and 12 weeks. Detailed histology revealed that the HA pores were completely "locked" by the polymer leading to complete loss of the osteoconductive properties of the HA. Also electron microscopy showed filling of the HA pores by the polymer. Therefore, it can be concluded that glycerol-l-lactide should not be used to coat HA ceramic implants due to significant delay in bone ingrowth.
    Journal of Controlled Release 09/2005; 106(1-2):154-61. · 7.63 Impact Factor
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    ABSTRACT: Although calcification of the Achilles tendon has been described by several authors, a detailed evaluation of its frequency and effects on clinical outcome has not been reported. The purposes of this work were to determine the frequency of calcifications in the Achilles tendon after open repair and their effects on clinical outcomes and to identify possible risk factors for postoperative calcification. Thirty-six patients with open Achilles tendon repair were evaluated at an average followup of 19 months. Evaluation included a self-assessment questionnaire concerning treatment outcomes, clinical examination, and radiographic and ultrasonographic examinations. No patient had calcifications in the Achilles tendon area before surgery. Postoperatively, intratendinous or peritendinous calcifications, ranging in size from 3 mm to 37 mm, were found in 10 (28%) of the 36 patients. The development of calcifications was associated with chronic swelling, decreased range of motion of the ankle joint, and increase pain, especially with calcifications larger than 10 mm. No association was found between the development of calcifications and the surgical technique, suture materials, time from injury to surgery, or postoperative management, and no risk factors could be identified. Calcifications of the Achilles tendon appear to be frequent after open tendon repair and to have a negative effect on clinical outcome.
    Foot & Ankle International 12/2004; 25(11):827-32. · 1.47 Impact Factor
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    ABSTRACT: Basic fibroblast growth factor (bFGF)-coated hydroxyapatite (HA) cylinders showed good bony incorporation in a previously conducted animal study. However, some cylinders exhibited focal inhomogeneous bone ingrowth. The purpose of the current study was to test whether glycerol-L-lactide polymer coating could improve release properties and bone incorporation of bFGF-coated HA implants. bFGF-coated HA cylinders with or without coating polymer were investigated for in vitro release of bFGF by an immuno-ligand-assay and also for bone ingrowth in miniature pigs after 42 and 84 days. Release from bFGF polymer composites was lower for the first 3 days compared to the other group but was more homogenous and detectable amounts were still found after 20 days. There was significant delay in bone ingrowth of the polymer implants in which even after 84 days bone ingrowth was not completed, whereas in the other group incorporation after 42 days occurred. Detailed histology revealed filling of the HA pores with the polymer, making ingrowth of the surrounding host bone impossible. Only after 84 days starting resorption of the polymer accompanied by bone ingrowth was found. The current study showed that glycerol-L-lactide is not suitable for coating of HA implants due to polymer induced "locking" of HA pores.
    Journal of Controlled Release 10/2004; 99(1):103-11. · 7.63 Impact Factor
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    ABSTRACT: Background and Purpose:Synthetically manufactured bone substitute materials are widely used to fill cancellous bone defects in fracture treatment. By using these materials, complications occurring with the harvesting of autologous bone such as inflammation, hemorrhage and pain are prevented. Ideally, after osteointegration, the bone substitute resorbs, and complete restoration of bone architecture is achieved. Until now, clinical experience is limited to non-fully resorbable calcium phosphates, e. g., hydroxyapatite. Previous studies have revealed a fully resorbable pure calcium phosphate, which is applied in a paste form as a bone implant and results in complete resorption and biocompatibility. The purpose of this prospective, uncontrolled clinical study was to investigate the safety and performance of this new resorbable bone substitute material.Patients and Methods:In 107 patients, bone defects were filled with 1.0–27.5 g (median 5.45 g) of the bone substitute material. From 15 patients, biopsy samples for histological examination could be taken during secondary surgery, mostly when implants for osteosynthesis had to be removed.Results:On clinical, radiologic and histological examination, the bone substitute material studied appeared safe and efficient for filling bone defects in fracture treatment, showing resorption and osseous integration during remodeling of bone. No clinical signs of allergic reactions or inflammation did occur.Conclusion:When using calcium phosphate bone cement, a second surgical procedure to harvest autologous bone is not necessary and complications at the donor site are avoided.
    European Journal of Trauma 01/2004; 30(1):17-22.
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    ABSTRACT: We report the case of an isolated cuboid bone fracture in a child that was missed on radiography but was diagnosed on sonography. Plain radiographs of the patient's right foot showed no fracture, whereas sonograms demonstrated a fracture of the cuboid bone that appeared as a steplike discontinuity in the cortical bone. The diagnosis was confirmed on MRI. The fracture was treated with cast immobilization and no weight bearing for 4 weeks. In 8 weeks, the patient had no symptoms and good motor and sensory function of her right foot. Other imaging modalities are usually advocated for diagnosing fractures that are missed by radiography. Over the last decade, sonography has been increasingly used for diagnosing occult fractures. Although its use in such cases is not yet fully established, we believe that in the future, the sonographic detection of an injury that corresponds to the site of the reported pain will be adequate for initiating treatment of many types of fractures.
    Journal of Clinical Ultrasound 01/2004; 32(3):154-7. · 0.70 Impact Factor
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    ABSTRACT: Patients with osteolytic metastases frequently suffer from serious local and radicular pain. Pathophysiologically, local pain arises from skeletal instability, whereas radicular pain originates from compression of nerve roots by local tumor growth. Causal treatment of osteolytic metastases in disseminated malignant disease is very difficult. Resection of vertebrae, in combination with ventro-dorsal stabilization, is a complex treatment for patients with a limited life expectancy. Percutaneous polymethylmethacrylate (PMMA) vertebroplasty is a new and easy method of relieving patients' pain. In addition, it is both cost effective and safe. Pain is reduced immediately after treatment. Due to the regained vertebral stability, early mobilization of the patients is possible. A total of 22 patients with osteolytic malignancies of the thoracic and lumbar spine were treated with PMMA vertebroplasty. Prior to and after surgery, then six weeks and six months after discharge from hospital, patients answered the Oswestry Low Back Pain Disability (OLBPD) Questionnaire for assessment of treatment-related change in disability. Percutaneous vertebroplasty was performed in a total of 19 patients. In three patients with tumor related compression of nerve roots an open neurolysis was performed followed by vertebroplasty. A total of 86% of patients reported a significant pain reduction. Vertebroplasty was highly beneficial for patients with pain related to local instability of the spine, but less so in patients with additional nerve root compression. Extravasation of PMMA beyond the vertebral margins was observed in 23% of the cases. No treatment-related clinical or neurological complications were seen. PMMA vertebroplasty is a useful and safe method of pain relief for patients with malignant osteolytic diseases of the thoracic and lumbar spine.
    German medical science : GMS e-journal 02/2003; 1:Doc08.
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    ABSTRACT: Background: Major osseous defects in trauma or tumor patients require surgical reconstruction. While transplantation of autogenous or allogenous bone is still regarded as the standard, a multitude of alternative substitute materials has been developed in the recent years. Currently, the majority of commercially available products is based on calcium phospate minerals which are known to be osteoconductive, but in which resorption occurs slowly, if at all. A new class of calcium phosphate cements has recently been introduced that may offer better resorbability due to their nanocrystalline structure. Patients and Methods: In a prospective study of eleven patients with twelve joint depression calcaneal fractures requiring open reduction and internal stabilization, the subchondral defects were filled with a novel nanocrystalline calcium phosphate cement (Biobon®). Nine patients with ten fractures underwent a 1-year clinical and radiologic follow-up. Results: The postoperative course was uneventful except for one postoperative infection. On follow-up X-rays, the contours of the cement material became blurred and its size decreased. Biopsies taken after 6–8 months during plate removal demonstrated residual cement with intense osseointegration. Signs of inflammatory tissue response were absent, and part of the material had been replaced by new bone. Conclusions: The substitute material investigated in this study has a high biocompatibility and may represent an interesting alternative to bone grafts. Compared to sintered calcium phosphates, the resorbability of the new cement appears superior due to its nanocrystalline structure. The low compressive strength, however, does not permit early weight bearing and requires additional stabilization with osteosynthetic implants.
    European Journal of Trauma 28(6):340-348.