Stefan Rammelt

Publications of Stefan Rammelt

• Direct plantar approach to Henry's knot for flexor hallucis longus transfer.

  Authors: Michael Amlang, Maria C Rosenow, Adina Friedrich, Hans Zwipp, Stefan Rammelt

  Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society. 01/2012; 33(1):7-13.

  Transfer of the flexor hallucis longus (FHL) tendon is an established method to replace a dysfunctional Achilles tendon. When using a single incision, the FHL tendon has to be transferred as a singleTransfer of the flexor hallucis longus (FHL) tendon is an established method to replace a dysfunctional Achilles tendon. When using a single incision, the FHL tendon has to be transferred as a single stranded graft into the calcaneus and the distal FHL stump cannot be directly attached to the flexor digitorum longus tendon (FDL). Another concern with tendon retrieval is neurovascular damage. We report our results with a direct plantar approach for tendon harvest. A direct plantar approach to the master knot of Henry with reattachment to its distal stump while protecting the medial plantar nerve was used allowing a double stranded FHL-transfer in 25 cases of a severely dysfunctional Achilles tendon in 24 consecutive patients. Patients were evaluated prospectively and at an average followup of 73 (range, 20 to 121) months. No wound healing problems and no lesion of the medial plantar nerve occurred. The subjective result was rated as excellent in 18 (72%), good in five (20%), and fair in one case (8%).The AOFAS hindfoot score averaged 95.4 (range, 61 to 100) points and the AOFAS hallux score averaged 97.6 (range, 87 to 100) points. No loss of plantarflexion force was observed in the big toe as compared to the contralateral side. The plantar approach to Henry's knot allowed the use of a double stranded FHL transplant. The distal stump was attached to the FDL tendon to preserve flexion at the great toe without damaging to the medial plantar nerve.

• Delayed bone regeneration and low bone mass in a rat model of insulin-resistant type 2 diabetes mellitus is due to impaired osteoblast function.

  Authors: Christine Hamann, Claudia Goettsch, Jan Mettelsiefen, Veit Henkenjohann, Martina Rauner, Ute Hempel, Ricardo Bernhardt, Nadja Fratzl-Zelman, Paul Roschger, Stefan Rammelt, Klaus-Peter Günther, Lorenz C Hofbauer

  American journal of physiology. Endocrinology and metabolism. 09/2011; 301(6):E1220-8.

  Patients with diabetes mellitus have an impaired bone metabolism; however, the underlying mechanisms are poorly understood. Here, we analyzed the impact of type 2 diabetes mellitus on bone physiologyPatients with diabetes mellitus have an impaired bone metabolism; however, the underlying mechanisms are poorly understood. Here, we analyzed the impact of type 2 diabetes mellitus on bone physiology and regeneration using Zucker diabetic fatty (ZDF) rats, an established rat model of insulin-resistant type 2 diabetes mellitus. ZDF rats develop diabetes with vascular complications when fed a Western diet. In 21-wk-old diabetic rats, bone mineral density (BMD) was 22.5% (total) and 54.6% (trabecular) lower at the distal femur and 17.2% (total) and 20.4% (trabecular) lower at the lumbar spine, respectively, compared with nondiabetic animals. BMD distribution measured by backscattered electron imaging postmortem was not different between diabetic and nondiabetic rats, but evaluation of histomorphometric indexes revealed lower mineralized bone volume/tissue volume, trabecular thickness, and trabecular number. Osteoblast differentiation of diabetic rats was impaired based on lower alkaline phosphatase activity (-20%) and mineralized matrix formation (-55%). In addition, the expression of the osteoblast-specific genes bone morphogenetic protein-2, RUNX2, osteocalcin, and osteopontin was reduced by 40-80%. Osteoclast biology was not affected based on tartrate-resistant acidic phosphatase staining, pit formation assay, and gene profiling. To validate the implications of these molecular and cellular findings in a clinically relevant model, a subcritical bone defect of 3 mm was created at the left femur after stabilization with a four-hole plate, and bone regeneration was monitored by X-ray and microcomputed tomography analyses over 12 wk. While nondiabetic rats filled the defects by 57%, diabetic rats showed delayed bone regeneration with only 21% defect filling. In conclusion, we identified suppressed osteoblastogenesis as a cause and mechanism for low bone mass and impaired bone regeneration in a rat model of type 2 diabetes mellitus.

• Immune responses to implants - a review of the implications for the design of immunomodulatory biomaterials.

  Authors: Sandra Franz, Stefan Rammelt, Dieter Scharnweber, Jan C Simon

  Biomaterials. 06/2011; 32(28):6692-709.

  A key for long-term survival and function of biomaterials is that they do not elicit a detrimental immune response. As biomaterials can have profound impacts on the host immune response the conceptA key for long-term survival and function of biomaterials is that they do not elicit a detrimental immune response. As biomaterials can have profound impacts on the host immune response the concept emerged to design biomaterials that are able to trigger desired immunological outcomes and thus support the healing process. However, engineering such biomaterials requires an in-depth understanding of the host inflammatory and wound healing response to implanted materials. One focus of this review is to outline the up-to-date knowledge on immune responses to biomaterials. Understanding the complex interactions of host response and material implants reveals the need for and also the potential of "immunomodulating" biomaterials. Based on this knowledge, we discuss strategies of triggering appropriate immune responses by functional biomaterials and highlight recent approaches of biomaterials that mimic the physiological extracellular matrix and modify cellular immune responses.

• Talus bipartitus: a rare skeletal variation: a report of four cases.

  Authors: Stefan Rammelt, Hans Zwipp, Andreas Prescher

  The Journal of bone and joint surgery. American volume. 03/2011; 93(6):e21.

• Stability of locking and non-locking plates in an osteoporotic calcaneal fracture model.

  Authors: Till Illert, Stefan Rammelt, Tim Drewes, René Grass, Hans Zwipp

  Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society. 03/2011; 32(3):307-13.

  The aim of this biomechanical cadaver study of calcaneal fractures was to investigate whether a locking calcaneal plate provides more stiffness in osteoporotic bone compared to a non-lockingThe aim of this biomechanical cadaver study of calcaneal fractures was to investigate whether a locking calcaneal plate provides more stiffness in osteoporotic bone compared to a non-locking plate. Sixteen fresh frozen bone mineral density (BMD)-matched cadaver feet were tested in a four-part model of a Sanders Type IIB calcaneal fracture. The fractures were fixed either with a non-locking AO (Sanders) plate or an interlocking AO plate (Synthes, Paoli, PA) to the lateral calcaneal wall with six screws. Specimens were subjected to cyclic loading which was increased stepwise to full body weight. Displacement of the posterior facet fragment was measured with an optical tracking system in the sagittal and transverse planes. No statistically significant differences were observed between the non-locking and the locking plates with respect to number of cycles to failure or 1-mm displacement of the posterior facet. The initial stiffness was significantly higher for non-locking plates. In osteoporotic bone, the greater stiffness of the screw-locking-plate construct was offset by the smaller diameter of the screw threads and the lower friction between the plate and bone when a locking plate was used. In clinical practice, the plate should first be compressed to osteoporotic bone with cancellous screws and at least two screws should be placed in the anterior process and in the tuberosity of the calcaneus.

• Postural control and functional ankle stability in professional and amateur dancers.

  Authors: Susanne Rein, Tobias Fabian, Hans Zwipp, Stefan Rammelt, Stefan Weindel

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 03/2011; 122(8):1602-10.

  The aim of this study was to compare the postural control and functional ankle stability between professional and amateur dancers as well as controls. Thirty professional dancers were compared toThe aim of this study was to compare the postural control and functional ankle stability between professional and amateur dancers as well as controls. Thirty professional dancers were compared to thirty amateur dancers and thirty controls. All participants (n=90) completed a questionnaire. Range of motion (ROM), ankle position sense and peroneal reaction time (PRT) were measured. Postural control was investigated with the Biodex Stability System (BSS) for the stable level 8 and the unstable level 2. Professional dancers showed a significantly increased plantarflexion of both feet in comparison to all other groups (P ≤ 0.017). Even amateur dancers had a significantly increased plantarflexion of both feet in comparison to controls (P ≤ 0.017). The position sense test only showed significant differences between professionals, amateurs and controls at the position of 130° for the right leg (P ≤ 0.017). The PRT showed no significant differences among all groups except for the left peroneus brevis of amateur dancers in comparison to controls (P ≤ 0.017). Professional dancers had a significant better postural control in comparison to amateurs and controls for levels 8 and 2 at all tested positions (P ≤ 0.017). In addition, professional dancers had a specific balance distribution, whereas they balanced significantly more in the antero-lateral and less in the postero-medial part of their feet in comparison with amateur dancers and controls (P ≤ 0.017). Despite a greater ROM, professional dancers have a better control of postural stability due to a specific balance distribution. However, the position sense test and the PRT were not influenced by the profession. The specific work-related demands of ankle joints did not improve all components of functional ankle stability in professional dancers. Therefore, the inclusion of proprioceptive exercises in the daily training program is highly recommended, aiming to improve functional ankle stability and thus to minimize the risk of ankle injuries.

• Fracture models in the lumbar sheep spine: a biomechanical investigation.

  Authors: Jan Heineck, Cornelius Haupt, Karin Werner, Stefan Rammelt, Hans Zwipp, Hans-Joachim Wilke

  Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 06/2010; 28(6):773-7.

  The purpose of this study was to find out if a limited resection of the cranial vertebral body leaving the posterior wall intact is a sufficient model for AO type 3 fractures, or if additionalThe purpose of this study was to find out if a limited resection of the cranial vertebral body leaving the posterior wall intact is a sufficient model for AO type 3 fractures, or if additional resection of the posterior wall is necessary. In six, fresh-frozen, lumbar sheep spine specimens, the segmental stability was tested in three motion planes in a spine tester. First, the intact specimens were tested. Then, partial resection of the intervertebral disc L3/4 and resection of the cranial vertebral body of L4 was performed, leaving the posterior wall intact. This defect was tested without instrumentation and with a ventral monosegmental interlocking plate mounted. Then, the defect was extended to a total cranial resection, including the posterior wall, and the tests were subsequently repeated. The stability of both types of defects under the different conditions was compared. Without instrumentation, the total cranial resection showed significantly more ROM in flexion/extension and axial rotation than partial cranial resection. With the ventral interlocking plate mounted, the instability in total cranial resection was significantly higher in flexion/extension, with the relative relation even being increased. In axial rotation and lateral bending, the differences were equalized by the mounted plate. From a biomechanical point of view, total cranial resection including the posterior wall should be preferred as a sheep spine fracture model for AO type 3 fractures.

• Histopathological, radiological and clinical aspects of the temporal assignment of scaphoid non-union.

  Authors: Susanne Rein, Uwe Hanisch, Stefan Rammelt, Günter Schmidt, Hans-Eberhardt Schaller, Hans Zwipp, Matthias Oehmke, Stefan Weindel

  Archives of orthopaedic and trauma surgery. 12/2009;

  OBJECTIVE: The aim of this study was to evaluate the correlation between clinical, radiological and histopathological signs of scaphoid non-unions (SNU) with regard to the age of the fracture,OBJECTIVE: The aim of this study was to evaluate the correlation between clinical, radiological and histopathological signs of scaphoid non-unions (SNU) with regard to the age of the fracture, primarily because this is relevant for therapy and compensation claims. MATERIALS AND METHODS: Thirty-eight patients with SNU underwent clinical and radiological examination of the wrist prior to surgery. Preoperative X-rays of the wrist were analysed using the scores of Herbert and Fisher, Filan and Herbert, Trojan and Jahna, Gupta as well as scaphoid non-union advanced collapse. Sclerotic bone of the SNU was resected during surgery. Resected material was evaluated histologically after staining with hematoxylin-eosin and periodic acid-Schiff reaction. Radiological and histological examinations were performed by independent investigators in a blinded fashion. RESULTS: The preoperative range of motion of the injured compared to the contralateral wrist was significantly reduced for the dorsi- and palmar flexion and for the radial and ulnar deviation; however, this reduction was not time dependent. There was no significant correlation between the radiological results and the age of the SNU, while fibrous tissue or fibrocartilage in the fracture gap was present in all cases. Significantly less fibrous or fibrocartilage bone cysts (p = 0.041) and bone remodelling (p = 0.031) were seen in older SNU (at 45 months). Definitive sclerotic bone covering of the fracture edges was significantly more common in older SNU (p = 0.035). CONCLUSION: Radiological and most of the conventional histological findings do not correlate with time after initial injury.

• Accuracy of corrective osteotomies in fibular malunion: a cadaver model.

  Authors: Jan Heineck, Alexandre Serra, Cornelius Haupt, Stefan Rammelt

  Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society. 09/2009; 30(8):773-7.

  BACKGROUND: While incorrect length of a fibular fracture reduction can be measured by plain radiographs, accurate imaging of rotational deformities requires computed tomography (CT). OperativeBACKGROUND: While incorrect length of a fibular fracture reduction can be measured by plain radiographs, accurate imaging of rotational deformities requires computed tomography (CT). Operative correction of fibular malrotation has not been accurately measured. The aim of this study was to evaluate the accuracy of operative correction of fibular malrotation. MATERIALS AND METHODS: Six pairs of formalin-fixed, lower leg cadaver specimens had shortening with additional internal or external rotation induced by segmental fibular resection and plate fixation. The deformity was measured by CT. Two experienced surgeons performed standardized corrective operations on six specimens each. The postoperative results were measured by CT. RESULTS: The mean overall accuracy for correction of malrotation was 1.58 degrees (SD = 0.8 degrees). There were no significant differences between the two surgeons performing the corrections. CONCLUSION: The accuracy of operative correction of malrotation in this cadaver model is in accordance with the requirements reported in clinical studies. CLINICAL RELEVANCE: Considering the error margin for CT analysis, correction within 5 to 10 degrees seems practical.

• High Union Rates and Function Scores at Midterm Followup With Ankle Arthrodesis Using a Four Screw Technique.

  Authors: Hans Zwipp, Stefan Rammelt, Thomas Endres, Jan Heineck

  Clinical orthopaedics and related research. 09/2009;

  When evaluating the role of ankle arthrodesis in the treatment of severe ankle arthritis, postoperative infection, nonunion, and the development of arthritis at the adjacent joints are major issuesWhen evaluating the role of ankle arthrodesis in the treatment of severe ankle arthritis, postoperative infection, nonunion, and the development of arthritis at the adjacent joints are major issues when considering treatment alternatives. We evaluated the rate of complications, the functional outcome, and compensatory range of motion at the midtarsal joint at medium-term followup after ankle arthrodesis with four cancellous screws. We performed 94 ankle fusions in 92 patients; 12 patients were lost to followup and eight declined to participate, leaving 72 patients (76%) for evaluation. The minimum followup was 4.8 years (mean, 5.9; range, 4.8-7.8 years). No patient developed a deep infection; three patients developed postoperative hematoma which we operatively drained. Union occurred in 93 of the 94 patients (99%). The sagittal motion at the midtarsal joint averaged 24 degrees . Secondary arthritis of the subtalar and talonavicular joints developed during the followup period in 17% and 11%, respectively. Progression of preexisting arthritis occurred in 13 of 43 patients (30%) at the subtalar joint and five of 26 patients (19%) at the talonavicular joint. None of these patients had fusion of an adjacent joint. The average American Orthopaedic Foot and Ankle Society score increased from 36 preoperatively to 85 at followup. Ankle arthrodesis with screws provides high rates of union, reliable pain relief, and favorable functional medium-term results. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

• Percutaneous Treatment of Less Severe Intraarticular Calcaneal Fractures.

  Authors: Stefan Rammelt, Michael Amlang, Sven Barthel, Johann Marian Gavlik, Hans Zwipp

  Clinical orthopaedics and related research. 08/2009;

  Percutaneous treatment of calcaneal fractures is intended to reduce soft tissue complications and postoperative stiffness of the subtalar joint. We assessed the complications, clinical hindfootPercutaneous treatment of calcaneal fractures is intended to reduce soft tissue complications and postoperative stiffness of the subtalar joint. We assessed the complications, clinical hindfoot alignment, motion, functional outcome scores, and radiographic correction of percutaneous arthroscopically assisted reduction and screw fixation of selected, less severe fractures. We performed percutaneous reduction and screw fixation in 61 patients with Type II (Sanders et al.) calcaneal fractures. In 33 of 61 patients with displaced intraarticular fractures (types IIA and IIB), anatomic reduction of the subtalar joint was confirmed arthroscopically; these patients form the basis of this report. We observed no wound complications or infections. In two patients, one prominent screw was removed after 1 and 3 years, respectively. In one patient, arthroscopic arthrolysis was performed 1 year after the index procedure. Twenty-four of 33 patients (73%) were followed a minimum of 24 months (mean, 29 months; range, 24-67 months). The average American Orthopaedic Foot and Ankle Society ankle-hindfoot score at last followup was 92.1 (range, 80-100). Böhler's angle and calcaneal width were reduced close to the values of the uninjured side. We believe percutaneous fixation is a reasonable alternative for moderately displaced Type II fractures provided adequate control over anatomic joint reduction with either subtalar arthroscopy or high-resolution (3-D) fluoroscopy. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

• Injuries to the distal tibiofibular syndesmosis: an evidence-based approach to acute and chronic lesions.

  Authors: Stefan Rammelt, Hans Zwipp, René Grass

  Foot and ankle clinics. 01/2009; 13(4):611-33.

  Injuries to the distal tibiofibular syndesmosis are frequent in collision sports. Most of these injuries are not associated with latent or frank diastasis between the distal tibia and fibula and areInjuries to the distal tibiofibular syndesmosis are frequent in collision sports. Most of these injuries are not associated with latent or frank diastasis between the distal tibia and fibula and are treated as high ankle sprains, with an extended protocol of physical therapy. Relevant instability of the syndesmosis results from rupture of two or more ligaments leading to a diastasis of more than 2 mm and requiring surgical fixation. Most of these syndesmosis ruptures are associated with bony avulsions or malleolar fractures. Treatment consists of anatomic reduction of the fibula and fixation with one or two tibiofibular syndesmosis screws. Proper reduction and positioning of the screws are more predictive of a good clinical result than the material, size, and number of cortices purchased. Chronic injuries without instability are treated by arthroscopic or open debridement and arthrolysis. Chronic syndesmotic instability can be treated with a three-strand peroneus longus ligamentoplasty in the absence of symptomatic arthritis or bony defects.

• In vivo effects of modification of hydroxyapatite/collagen composites with and without chondroitin sulphate on bone remodeling in the sheep tibia

  Authors: Wolfgang Schneiders, Antje Reinstorf, Achim Biewener, Alexandr� Serra, Ren� Grass, Michael Kinscher, Jan Heineck, Sebastian Rehberg, Hans Zwipp, Stefan Rammelt

  Journal of Orthopaedic Research. 01/2009; 27:15--21.

  The addition of chondroitin sulphate (CS) to bone cements with calcium phosphate has lead to an enhancement of bone remodeling and an increase in new bone formation in small animals. The goal of thisThe addition of chondroitin sulphate (CS) to bone cements with calcium phosphate has lead to an enhancement of bone remodeling and an increase in new bone formation in small animals. The goal of this study was to verify the effect of CS in bone cements in a large animal model simulating a clinically relevant situation of a segmental cortical defect of a critical size on bone-implant interaction and bone remodeling. The influence of adding CS to hydroxyapatite/collagen (HA/Col) composites on host response was assessed in a standard sheep tibia model. A midshaft defect of 3 cm was created in the tibiae of 14 adult female sheep. The defect was filled with a HA/Col cement cylinder in seven animals and with a CS-modified hydroxyapatite/collagen (HA/Col/CS) cement cylinder in seven animals. In all cases the tibia was stabilized with an interlocked universal tibial nail. The animals in each group were analyzed with X-rays, CT scans, histology, immunohistochemistry, and enzymehistochemistry, as well as histomorphometric measurements. The X-ray investigation showed a significantly earlier callus reaction around the HA/Col/CS implants compared to HA/Col alone. The amount of newly formed bone at the end point of the experiment was significantly larger around HA/Col/CS cylinders both in the CT scan and in the histomorphometric analysis. There were still TRAP-positive osteoclasts around the HA/Col implants after 3 months. The number of osteopontin-positive osteoblasts and the direct bone contact were significantly higher around HA/Col/CS implants. We conclude that addition of CS enhances bone remodeling and new bone formation around HA/Col composites. � 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:15-21, 2009

• In vivo effects of modification of hydroxyapatite/collagen composites with and without chondroitin sulphate on bone remodeling in the sheep tibia.

  Authors: Wolfgang Schneiders, Antje Reinstorf, Achim Biewener, Alexandrè Serra, Renè Grass, Michael Kinscher, Jan Heineck, Sebastian Rehberg, Hans Zwipp, Stefan Rammelt

  Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 01/2009; 27(1):15-21.

  The addition of chondroitin sulphate (CS) to bone cements with calcium phosphate has lead to an enhancement of bone remodeling and an increase in new bone formation in small animals. The goal of thisThe addition of chondroitin sulphate (CS) to bone cements with calcium phosphate has lead to an enhancement of bone remodeling and an increase in new bone formation in small animals. The goal of this study was to verify the effect of CS in bone cements in a large animal model simulating a clinically relevant situation of a segmental cortical defect of a critical size on bone-implant interaction and bone remodeling. The influence of adding CS to hydroxyapatite/collagen (HA/Col) composites on host response was assessed in a standard sheep tibia model. A midshaft defect of 3 cm was created in the tibiae of 14 adult female sheep. The defect was filled with a HA/Col cement cylinder in seven animals and with a CS-modified hydroxyapatite/collagen (HA/Col/CS) cement cylinder in seven animals. In all cases the tibia was stabilized with an interlocked universal tibial nail. The animals in each group were analyzed with X-rays, CT scans, histology, immunohistochemistry, and enzymehistochemistry, as well as histomorphometric measurements. The X-ray investigation showed a significantly earlier callus reaction around the HA/Col/CS implants compared to HA/Col alone. The amount of newly formed bone at the end point of the experiment was significantly larger around HA/Col/CS cylinders both in the CT scan and in the histomorphometric analysis. There were still TRAP-positive osteoclasts around the HA/Col implants after 3 months. The number of osteopontin-positive osteoblasts and the direct bone contact were significantly higher around HA/Col/CS implants. We conclude that addition of CS enhances bone remodeling and new bone formation around HA/Col composites.

• Fifth metatarsal avulsion fracture: a rational basis for postoperative treatment.

  Authors: Jan Heineck, Martin Wolz, Cornelius Haupt, Stefan Rammelt, Wolfgang Schneiders

  Archives of orthopaedic and trauma surgery. 10/2008;

  BACKGROUND: Lacking rational basis for the postoperative treatment of fifth metatarsal avulsion fractures. METHODS: Biomechanical test of stability of tension banding and screw fixation of fifthBACKGROUND: Lacking rational basis for the postoperative treatment of fifth metatarsal avulsion fractures. METHODS: Biomechanical test of stability of tension banding and screw fixation of fifth metatarsal avulsion fractures in cadaver specimen, sonographic measuring of the maximum cross-section of the peroneus brevis muscle, electromyographic examinations of the activity of the peroneus brevis muscle at different loads and means of immobilization. RESULTS: The forces acting on the base of the fifth metatarsal bone during voluntary activation of the peroneus brevis muscle or activation in the gait cycle are of the same magnitude as the failure forces of internal fixation. Immobilization of the talocrural joint achieves no reduction in muscle activation. Partial weight bearing reduces muscle activation. CONCLUSIONS: The postoperative treatment after osteosynthesis of fifth metatarsal avulsion fractures should be partial weight bearing. For safety reasons we add an elastic ankle orthesis to prevent supination. A below-knee cast is not necessary.

• Effect of chondroitin sulphate on material properties and bone remodelling around hydroxyapatite/collagen composites.

  Authors: Wolfgang Schneiders, Antje Reinstorf, Michael Ruhnow, Sebastian Rehberg, Jan Heineck, Irene Hinterseher, Achim Biewener, Hans Zwipp, Stefan Rammelt

  Journal of biomedical materials research. Part A. 06/2008; 85(3):638-45.

  Chondroitin sulphate (CS) has an anti-inflammatory effect and increases the regeneration ability of injured bone. The goal of this study was to characterize the material properties andChondroitin sulphate (CS) has an anti-inflammatory effect and increases the regeneration ability of injured bone. The goal of this study was to characterize the material properties and osteoconductive potency of calcium phosphate bone cements modified with CS. The early interface reaction of cancellous bone to a nanokristalline hydroxyapatite cement containing type I collagen (HA/Coll) without and with CS (HA/Coll/CS) in a rat tibia model was evaluated. Cylindrical implants were inserted press-fit into defect of the tibial head. Six specimens per group were analyzed at 2, 4, 7, 14, and 28 days. HA/Coll/CS composite cylinders showed a 15% increase in compressive strength and by investigations with powder X-ray diffraction more nontransformed cement precursor was found. The microstructures of both types of implants were similar. A significantly higher average number of TRAP positive osteoclasts and ED1 positive mononuclear cells were observed in the interface around HA/Coll/CS implants on day 4 and 7 (p < 0.05). At 28 days the direct bone contact and the percentage of newly formed bone were significantly higher around HA/Coll/CS implants (p < 0.05). The addition of CS appears to enhance bone remodelling and new bone formation around HA/Coll composites in the early stages of bone healing. Possible mechanisms are discussed.

• Talar neck and body fractures.

  Authors: Stefan Rammelt, Hans Zwipp

  Injury. 05/2008;

  Fractures of the talar neck and body are rare and serious injuries. The vast majority are either intra-articular or lead indirectly to an intra-articular incongruity through a dislocation at theFractures of the talar neck and body are rare and serious injuries. The vast majority are either intra-articular or lead indirectly to an intra-articular incongruity through a dislocation at the talar neck. Because of the high energy needed to produce talar fractures, they are frequently seen in multiply injured and polytraumatised patients. Open fractures and fracture-dislocations are treated as emergencies. Preoperative planning of definite internal fixation requires CT scanning. To obtain a complete intra-operative overview allowing for anatomical reconstruction of the articular surfaces and the axial deviation bilateral approaches are usually necessary. Internal fixation is achieved with screws or mini-plates supplemented by temporary K-wire transfixation in cases of marked additional ligamentous instability. The clinical outcome after talar neck and body fractures is determined by the severity of the injury and the quality of reduction and internal fixation. The timing of definite internal fixation does not appear to affect the final result. The rates of avascular necrosis (AVN) correlate with the degree of initial dislocation. Only total AVN with collapse of the talar body leads to inferior results with the need for further surgery whilst prolonged immobilisation or offloading of the affected foot is not indicated for partial AVN. Talar malunions and non-unions after inadequate treatment of displaced fractures are debiliating conditions that should be treated by surgical correction. Treatment options include corrective osteotomy by recreating the former fracture with secondary fixation, free or vascularised bone grafting and salvage by realignment and fusion of the affected joint(s).

• Transsection of the rectus abdominis muscle in the treatment of acetabular fractures: operative technique and outcome in 21 patients.

  Authors: Jan Heineck, Stefan Rammelt, Rene Grass, Wolfgang Schneiders, Michael Amlang

  Acta orthopaedica. 05/2008; 79(2):225-9.

  BACKGROUND: A standard ilioinguinal approach is often insufficient for reduction and stabilization of the medial acetabular wall and the dorsal column in acetabular fractures. To avoid extendedBACKGROUND: A standard ilioinguinal approach is often insufficient for reduction and stabilization of the medial acetabular wall and the dorsal column in acetabular fractures. To avoid extended approaches, we have used a medial extension of the approach by transverse splitting of the rectus abdominis muscle. We have thus been able to reduce and stabilize transverse and oblique fractures of the dorsal column and the medial acetabular wall and to fix plates in a mechanically better position below the pelvic brim. To evaluate the procedure, especially the risk of abdominal hernia, we started a prospective study. PATIENTS AND METHODS: Over 2 years, we treated 21 consecutive patients using a transverse splitting of the rectus abdominis muscle-either as an extension of the standard ilioinguinal approach or in combination with parts of this approach or a Kocher-Langenbeck approach. The patients were evaluated clinically and radiographically after 1 year. RESULTS: The clinical and radiographic results were excellent or good in 18 patients. Complications occurred in 5 patients. No hernias were observed. CONCLUSIONS :Our small study indicates that the procedure described is a useful and safe complement to the intrapelvic approaches. The procedure does not provide better reduction than extended approaches, but may help to avoid them in some cases.

• In vivo effects of coating loaded and unloaded Ti implants with collagen, chondroitin sulfate, and hydroxyapatite in the sheep tibia.

  Authors: Stefan Rammelt, Christian Heck, Ricardo Bernhardt, Susanne Bierbaum, Dieter Scharnweber, Jürgen Goebbels, Jörg Ziegler, Achim Biewener, Hans Zwipp

  Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 08/2007; 25(8):1052-61.

  The in vivo effects of coating titanium implants with organic extracellular matrix molecules were examined in the sheep tibia. Titanium screws (5.0 mm) were coated with type I collagen (Ti/Coll) orThe in vivo effects of coating titanium implants with organic extracellular matrix molecules were examined in the sheep tibia. Titanium screws (5.0 mm) were coated with type I collagen (Ti/Coll) or type I collagen and chondroitin sulfate (Ti/Coll/CS) by biomimetic fibrillogenesis. Uncoated screws (Ti) and screws coated with hydroxyapatite (Ti/HA) served as control. Six adult female sheep received one screw of each type to stabilize a midshaft tibial fracture with external fixation. Four cylindrical implants of 4-mm outer diameter and 3.3-mm inner diameter with the same coatings were inserted into the tibial head. No pin track infections were seen at the time of implant retrieval 6 weeks after implantation. Extraction torque was greater for Ti/HA (1181 Nmm) and Ti/Coll/CS (1088 Nmm) compared to Ti/Coll (900 Nmm) and Ti (904 Nmm) [N.S.]. Newly formed bone was noted around all coated screws within the medullary cavity. Macrophage and osteoclast activity was significantly reduced around Ti/Coll/CS in both types of implants compared to uncoated controls (p < 0.05). Osteoblast activity was significantly increased around loaded Ti/Coll and Ti/Coll/CS screws compared to uncoated Ti screws (p < 0.05). Microtomographic evaluation (SRmicroCT) revealed no significant differences in new bone formation around the unloaded tibial head implants.Coating of external fixation devices with of type I collagen and chondroitin sulfate appears to have similar effects with respect to stability and bone healing as HA but with less osteoclast activity. These findings were more pronounced under loaded than unloaded conditions in the sheeptibia.

• Effect of modification of hydroxyapatite/collagen composites with sodium citrate, phosphoserine, phosphoserine/RGD-peptide and calcium carbonate on bone remodelling.

  Authors: Wolfgang Schneiders, Antje Reinstorf, Wolfgang Pompe, Rene Grass, Achim Biewener, Michael Holch, Hans Zwipp, Stefan Rammelt

  Bone. 05/2007; 40(4):1048-59.

  This study describes the early interface reaction of cancellous bone to a nanocrystalline hydroxyapatite cement containing type I collagen (HA/Coll) and its modifications with sodium citrate (CI),This study describes the early interface reaction of cancellous bone to a nanocrystalline hydroxyapatite cement containing type I collagen (HA/Coll) and its modifications with sodium citrate (CI), calcium carbonate (CA), phosphoserine (P) and phosphoserine plus RGD-peptide (RGD). Cylindrical implants of HA/Coll and its modifications were inserted into the tibia of Wistar rats. We analysed 6 specimens per group at days 2, 4, 7, 14 and 28. CI, P and RGD modifications showed improved material properties (finer microstructure and higher compressive strength) compared to CA and HA/Coll implants. The powder X-ray diffraction (XRD) showed that the addition of P and CI led to an increase of alpha-TCP peaks while the diffraction patterns of the non-modified cement (HA/Coll) were quite similar with that of natural bone. All of the implants healed without adverse reactions. A significantly higher number of TRAP-positive osteoclasts were observed around CI, RGD and P on day 7 compared to CA and HA/Coll. Around CI, P and RGD a significantly delayed increase of ED1-positive mononuclear cells was detected. The amount of direct bone contact after 28 days was significantly higher around CI, P and RGD compared to CA and HA/Coll implants. The addition of CI, P and RGD appears to enhance bone remodelling at the early stages of bone healing, leading to increased bone formation around HA/Coll composite cements.