Hans Zwipp

Publications of Hans Zwipp

• 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.

• 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.

• The influence of playing level on functional ankle stability in soccer players.

  Authors: Susanne Rein, Tobias Fabian, Stefan Weindel, Wolfgang Schneiders, Hans Zwipp

  Archives of orthopaedic and trauma surgery. 02/2011; 131(8):1043-52.

  The aim of this study was to compare the functional ankle stability between professional and amateur soccer players as well as controls. Thirty professional soccer players, 30 amateur soccer playersThe aim of this study was to compare the functional ankle stability between professional and amateur soccer players as well as controls. Thirty professional soccer players, 30 amateur soccer players and 30 controls were evaluated. All participants completed a questionnaire. Range of motion (ROM), peroneal reaction time (PRT) and ankle position sense were measured. Balance control was investigated with the Biodex Stability System, measuring the stable level 8 and the unstable level 2. Professional soccer players cited significantly more frequent ankle sprains than all other groups (P = 0.002). They showed a significantly decreased dorsiflexion of the right foot (amateur: P = 0.017; controls: P = 0.004), an increased pronation of both feet (amateurs: right: P = 0.0048, left: P = 0.006; controls: right: P = 0.017, left: P = 0.007) and a decreased supination of the left foot in comparison to all other groups (amateurs: P = 0.003; controls: P = 0.004). Balance control showed no significant differences among all groups. Significant differences in angle reproduction were observed between professionals and amateurs for the left ankle joint at the positions of 105° (P = 0.0018) and 140° (P = 0.013). Professionals (P = 0.004) and amateurs (P = 0.001) showed a significantly delayed PRT of the right peroneus longus muscle compared to controls. In addition, the PRT of the right peroneus brevis muscle was significantly increased in professional soccer players in comparison to controls (P = 0.017). Professional soccer players have shown more frequent ankle sprains, limited ROM, and delayed PRT of the right leg which reflects the higher risk of functional ankle instability due to intensified work-related use of feet. Therefore, proprioceptive exercises of the ankle in daily training programs are recommended in order to minimize the risk of ankle injuries and improve functional ankle stability.

• Long-bone critical-size defects treated with tissue-engineered polycaprolactone-co-lactide scaffolds: a pilot study on rats.

  Authors: Claudia Rentsch, Barbe Rentsch, Annette Breier, Kathrin Spekl, Roland Jung, Suzanne Manthey, Dieter Scharnweber, Hans Zwipp, Achim Biewener

  Journal of biomedical materials research. Part A. 12/2010; 95(3):964-72.

  The aim of this study was to evaluate the osteogenic potential of embroidered, tissue-engineered polycaprolactone-co-lactide (trade name: PCL) scaffolds for the reconstruction of large bone defects.The aim of this study was to evaluate the osteogenic potential of embroidered, tissue-engineered polycaprolactone-co-lactide (trade name: PCL) scaffolds for the reconstruction of large bone defects. Ten piled-up PCL scaffolds were implanted in femura with a critical size defect of immunodeficient nude rats for 12 weeks [n = 4, group 1: noncoated, group 2: collagen I (coll I), group 3: collagen I/chondroitin sulfate (coll I/CS), and group 4: collagen I/chondroitin sulfate/human mesenchymal stem cells (coll I/CS/hMSC)]. X-ray examination, computer tomography, and histological analyses of the explanted scaffold pads were performed. The quantification of the bone volume ratio showed a significantly higher rate of new bone formation at coll I/CS-coated scaffolds compared with the other groups. Histological investigations revealed that the defect reconstruction started from the peripheral bone ends and incorporated into the scaffold material. Additionally seeded hMSC on coll I/CS-coated scaffolds showed a higher matrix deposition inside the implant but no higher bone formation was observed. These data imply that the coll I/CS-coated PCL scaffolds have the highest potential for treating critical size defects. The scaffolds, being variable in size and structure, can be adapted to any bone defect.

• Invited commentary.

  Authors: Hans Zwipp

  Journal of orthopaedic trauma. 08/2010; 24(8):475-6; discussion 476.

• 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.

• Influence of age, body mass index and leg dominance on functional ankle stability.

  Authors: Susanne Rein, Tobias Fabian, Hans Zwipp, Martina Mittag-Bonsch, Stefan Weindel

  Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society. 05/2010; 31(5):423-32.

  The aim of this study was to examine the influence of age, body mass index (BMI) and leg dominance on the PRT, balance control and foot position sense. The proprioception of the ankle wasThe aim of this study was to examine the influence of age, body mass index (BMI) and leg dominance on the PRT, balance control and foot position sense. The proprioception of the ankle was investigated in 210 participants. All participants completed a questionnaire. The PRT was measured on a tilting platform. The position sense test was performed. Balance control was assessed with the Biodex Stability System (BSS), measuring the overall stability index (OSI) at the stable level 8 and the unstable level 2. Correlation analyses were performed between these data and age, BMI and leg dominance, using the Spearman-Rho coefficient with a two-sided significance level of p < 0.05. Significant increases of the PRT and OSI in correlation to increased age and BMI were noted for both legs (p < 0.05). No positive correlation to age, BMI or leg dominance could be demonstrated for the foot position sense test. The PRT of the right leg was always significantly faster than that of the left leg, irrespective of leg dominance (p < 0.05). Surprisingly, individuals with a dominant right leg achieved better OSI scores in left single leg stance at the unstable level 2 (p < 0.05). The PRT and the postural stability correlate with age and BMI, whereas the position sense test of the ankle does not. Furthermore, the PRT in right legs is always faster. This should be noted when functional ankle stability is evaluated in patients.

• The influence of profession on functional ankle stability in musicians.

  Authors: Susanne Rein, Tobias Fabian, Hans Zwipp, Jan Heineck, Stefan Weindel

  Medical problems of performing artists. 03/2010; 25(1):22-8.

  The aim of this study was to examine the influence of extensive work-related use of the feet on functional ankle stability among musicians. Thirty professional organists were compared to professionalThe aim of this study was to examine the influence of extensive work-related use of the feet on functional ankle stability among musicians. Thirty professional organists were compared to professional pianists and controls. All participants completed a questionnaire. Range of motion (ROM), peroneal reaction time, and positional sense tests of the ankle were measured. The postural balance control was investigated with the Biodex Stability System for the stable level 8 and unstable level 2. Statistical analysis was done with the Kruskal-Wallis test, Mann-Whitney test with Bonferroni-Holm correction, and Fisher's exact test. Nine of 30 organists compared to 5 of 30 pianists and controls reported ankle sprains in their medical history. Pianists had a significant increased flexion of both ankle joints compared to organists (p < 0.01) and increased flexion of the right ankle joint compared to controls (p = 0.02). The positional sense test and postural balance control showed no significant differences among groups. The peroneal reaction time of the right peroneus longus muscle was significantly increased in pianists compared to controls (p = 0.008). Organists have shown a high incidence of ankle sprains. Despite their extensive work-related use of the ankle joints, organists have neither increased functional ankle stability nor increased ROM of their ankle joints in comparison to controls. Pianists have increased flexion of the ankle joint, perhaps due to the exclusive motion of extension and flexion while using the pedals. To minimize injuries of the ankle and improve functional ankle stability as well as balance control, proprioceptive exercises of the ankle in daily training programs are recommended.

• 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.

• 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.

• Evaluation of the proprioceptive influence of the cutaneous afferents to the ankle in patients after sural nerve harvesting.

  Authors: Susanne Rein, Tobias Fabian, Kartik Krishnan, Stefan Benesch, Gabriele Schackert, Hans Zwipp, Claudia Lindner, Stefan Weindel

  Neurosurgery. 04/2009; 64(3):519-25; discussion 526.

  OBJECTIVE: Cutaneous afferent nerves contribute to joint proprioception. The aim of this study was to retrospectively analyze the proprioceptive influence of the cutaneous afferents to the ankle inOBJECTIVE: Cutaneous afferent nerves contribute to joint proprioception. The aim of this study was to retrospectively analyze the proprioceptive influence of the cutaneous afferents to the ankle in patients after sural nerve harvesting in comparison to controls. METHODS: The proprioception of the ankle in 24 patients after sural nerve harvesting was investigated. The sural nerve was harvested bilaterally in Group 1 (n = 10), in the right leg in Group 2 (n = 6), and in the left leg in Group 3 (n = 8). The proprioception of the ankle was also tested in controls (Group 4, n = 24). The peroneal reaction time (PRT) was measured on a tilting platform. The position sense test was performed. Balance control was investigated with the Biodex Stability System (Biodex Medical Systems, Shirley, NY) at the stable Level 8 and unstable Level 2. RESULTS: No significant differences among the groups were seen in the position sense test, the PRT, and all scores of the Biodex Stability System. The PRT showed significant differences in comparison to the contralateral leg for the peroneus brevis muscle in Group 1 (P = 0.005) and Group 4 (P = 0.001) as well as for the peroneus longus muscle in Group 3 (P = 0.036) and Group 4 (P = 0.001). CONCLUSION: The proprioception of the ankle in patients after sural nerve harvesting is not reduced in comparison to controls. Significant differences of the PRT between the left and right legs are attributable to leg dominance in most cases and not to a loss of innervation. Harvesting of the sural nerve does not result in ankle instability.

• Evaluation of the osteogenic potential and vascularization of 3D poly(3)hydroxybutyrate scaffolds subcutaneously implanted in nude rats.

  Authors: Claudia Rentsch, Barbe Rentsch, Annette Breier, Andre Hofmann, Suzanne Manthey, Dieter Scharnweber, Achim Biewener, Hans Zwipp

  Journal of biomedical materials research. Part A. 02/2009;

  The aim of this study was to evaluate the osteogenic potential and the vascularization of embroidered, tissue engineered, and cell-seeded 3D poly(3)hydroxybutyrate (PHB) scaffolds in nude rats.The aim of this study was to evaluate the osteogenic potential and the vascularization of embroidered, tissue engineered, and cell-seeded 3D poly(3)hydroxybutyrate (PHB) scaffolds in nude rats. Collagen I (coll I)- and collagen I/chondroitin sulfate (coll I/CS)-coated PHB scaffolds were seeded with human mesenchymal stem cells (hMSCs). Proliferation and differentiation were characterized by different biochemical assays in vitro. For animal experiments, the cells were cultivated on coll I- or coll I/CS-coated scaffolds and either expanded or osteogenically differentiated. Scaffolds were piled up to create a 3D scaffold pad and implanted subcutaneously into nude rats. In vitro hMSC showed proliferation and differentiation on PHB scaffolds. Alkaline phosphatase (ALP) and calcium increased in the differentiation medium and in the presence of coll I/CS. In vivo blood vessels were found in the scaffold-stack. Histological/immunohistological analyses of explanted scaffolds showed osteogenic markers such as osteopontin, osteonectin, and coll I around the PHB fibers. Coll I/CS-coated scaffolds with expanded hMSC showed higher values of ALP and calcium than the other combinations. Embroidered PHB scaffolds, coated with extracellular matrix components, provided an adequate environment and, therefore, a template for hMSC which could be differentiated in osteogenic direction. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 2009.

• 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.

• 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).