Wolfgang Schneiders

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

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 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.

Severity of Injury Predicts Subsequent Function in Surgically Treated Displaced Intraarticular Calcaneal Fractures

BackgroundThe treatment of displaced, intraarticular calcaneal fractures (DIACFs) remains challenging and the best treatment choices remain controversial. The majority of patients will have some lasting functional restrictions. However, it is unclear which patient- or surgeon-related factors predict long-term function.Questions/purposesWe determined (1) the impact of patient- and surgeon-related factors on function of patients after internal fixation of DIACFs and (2) whether severity of injury correlated with subsequent function.MethodsWe retrospectively reviewed all 210 patients operatively treated for 242 DIACFs between 2000 and 2003; of these, 127 patients (60%) with 149 fractures were available for followup at a minimum of 69 months (average, 95 months; range, 69–122 months). Severity of injury was quantified by the classifications of Sanders and Zwipp Function was quantified using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, an adjusted Zwipp score, the Foot Function Index (FFI), and the SF-36 physical and mental component summary (PCS and MCS) scores.ResultsAt latest followup, the median AOFAS score was 77, the median Zwipp score was 60, the median FFI was 27, and the median SF-36 PCS and MCS scores were 44 and 55, respectively. The foot-related scores and the SF-36 PCS negatively correlated with the severity of injury, work-related injuries, and bilateral fractures.ConclusionsWe found the severity of a DIACF related to subsequent foot function and quality of life. Both fracture severity classifications predicted function. Anatomic reconstruction of the shape and articular surfaces of the calcaneus leads to predictable function in the medium to long term.Level of EvidenceLevel IV, prognostic study. See Instructions for Authors for a complete description of levels of evidence.

Surface modification of implants in long bone

Coatings of orthopedic implants are investigated to improve the osteoinductive and osteoconductive properties of the implant surfaces and thus to enhance periimplant bone formation. By applying coatings that mimic the extracellular matrix a favorable environment for osteoblasts, osteoclasts and their progenitor cells is provided to promote early and strong fixation of implants. It is known that the early bone ongrowth increases primary implant fixation and reduces the risk of implant failure. This review presents an overview of coating titanium and hydroxyapatite implants with components of the extracellular matrix like collagen type I, chondroitin sulfate and RGD peptide in different small and large animal models. The influence of these components on cells, the inflammation process, new bone formation and bone/implant contact is summarized.

Anatomic Reconstruction of Malunited Chopart Joint Injuries

Fractures and dislocations at the mid-tarsal (Chopart) joint are frequently overlooked or misinterpreted at first presentation. Inadequate joint reduction and stabilization almost invariably lead to painful malunions or nonunions, residual instability, and deformity. Because of the central position and the essential function of the mid-tarsal joint, malunions lead to a considerable impairment of global foot function and the rapid development of posttraumatic arthritis. While secondary anatomical reconstruction with joint preservation would be desirable in order to restore normal foot function, it is amenable only if no symptomatic arthritis or avascular necrosis is present. Over a course of 6 years, eight patients have been treated with secondary correction, joint realignment, and internal fixation. In four of these cases, nonunions of the tarsal navicular were debrided and bone-grafted; in the remaining cases, a corrective osteotomy at the navicular or cuboid was carried out. At 2 years followup, all but one patient were satisfied with the result. One patient underwent fusion of the talonavicular joint for avascular necrosis and collapse of the navicular. The mean American Orthopaedic Foot and Ankle Score (AOFAS) improved significantly from 38.8 preoperatively to 80.8 at follow-up. However, the majority of malunited mid-tarsal fracture-dislocations will require corrective fusion of the affected joint(s) with axial realignment because of manifest posttraumatic arthritis at the time of patient presentation.

Embroidered and surface coated polycaprolactone-co-lactide scaffolds A potential graft for bone tissue engineering

Tissue engineering and regenerative techniques targeting bone include a broad range of strategies and approaches to repair, augment, replace or regenerate bone tissue. Investigations that are aimed at optimization of these strategies until clinical translation require control of systemic factors as well as modification of a broad range of key parameters. This article reviews a possible strategy using a tissue engineering approach and systematically describes a series of experiments evaluating the properties of an embroidered and surface coated polycaprolactone-co-lactide scaffold being considered as bone graft substitute for large bone defects. The scaffold design and fabrication, the scaffolds properties, as well as its surface modification and their influence in vitro are evaluated, followed by in vivo analysis of the scaffolds using orthotopic implantation models in small and large animals.

Comprehensive histological evaluation of bone implants

To investigate and assess bone regeneration in sheep in combination with new implant materials classical histological staining methods as well as immunohistochemistry may provide additional information to standard radiographs or computer tomography. Available published data of bone defect regenerations in sheep often present none or sparely labeled histological images. Repeatedly, the exact location of the sample remains unclear, detail enlargements are missing and the labeling of different tissues or cells is absent. The aim of this article is to present an overview of sample preparation, staining methods and their benefits as well as a detailed histological description of bone regeneration in the sheep tibia. General histological staining methods like hematoxylin and eosin, Masson-Goldner trichrome, Movats pentachrome and alcian blue were used to define new bone formation within a sheep tibia critical size defect containing a polycaprolactone-co-lactide (PCL) scaffold implanted for 3 months (n = 4). Special attention was drawn to describe the bone healing patterns down to cell level. Additionally one histological quantification method and immunohistochemical staining methods are described.

Healing properties of surface-coated polycaprolactone-co-lactide scaffolds: A pilot study in sheep

The aim of this pilot study was to evaluate the bioactive, surface-coated polycaprolactone-co-lactide scaffolds as bone implants in a tibia critical size defect model. Polycaprolactone-co-lactide scaffolds were coated with collagen type I and chondroitin sulfate and 30 piled up polycaprolactone-co-lactide scaffolds were implanted into a 3 cm sheep tibia critical size defect for 3 or 12 months (n = 5 each). Bone healing was estimated by quantification of bone volume in the defects on computer tomography and microcomputer tomography scans, plain radiographs, biomechanical testing as well as by histological evaluations. New bone formation occurred at the proximal and distal ends of the tibia in both groups. The current pilot study revealed a mean new bone formation of 63% and 172% after 3 and 12 months, respectively. The bioactive, surface coated, highly porous three-dimensional polycaprolactone-co-lactide scaffold stack itself acted as a guide rail for new bone formation along and into the implant. These preliminary data are encouraging for future experiments with a larger group of animals.

Die Korrekturarthrodese des Lisfranc-Gelenks nach fehlverheilten Luxationsfrakturen

ZusammenfassungFehlverheilte Luxationsfrakturen im Lisfranc-Gelenk führen regelhaft zu schmerzhaften Fehlstellungen mit erheblichen Funktionseinschränkungen für die betroffenen Patienten. Die Ursachen liegen zum einen in primär übersehenen, zum anderen in unterschätzten und inadäquat behandelten Verletzungen. Je nach primärer Luxationsrichtung resultiert eine Abduktion oder Adduktion des Vorfußes mit einer begleitenden Platt- oder Hohlfußbildung.Ziel der reorientierenden Arthrodese des tarsometatarsalen Übergangs ist die Wiederherstellung der Achsenverhältnisse und Stabilisierung von chronischen Instabilitäten, insbesondere nach rein ligamentären Verletzungen. Nach Möglichkeit sollte die Arthrodese auf die medialen 3 Strahlen beschränkt bleiben, wenn sich hierdurch auch eine korrekte Ausrichtung der 2 lateralen Strahlen erreichen lässt.Die Korrekturarthrodese führt zu einer deutlichen Beschwerdeminderung und einem erheblichen Funktionsgewinn mit einer Patientenzufriedenheit zwischen 69 und 100% in der Literaturübersicht. Günstige Prognosefaktoren sind die anatomische Achsenkorrektur und die Begrenzung der Fusion auf den I. bis III. Strahl.AbstractMalunited fracture dislocations at the tarsometatarsal (Lisfranc’s) joint regularly lead to painful deformities with severe functional impairment for the affected patients. Malunions result from initially overlooked injuries as well as from misjudged and inadequately treated injuries. Depending on the nature of the primary dislocation, either abduction or adduction of the forefoot will result, accompanied by a planus or cavus deformity.Corrective arthrodesis aims at axial realignment at the tarsometatarsal junction, and elimination of residual instabilities especially after pure ligamentous injuries. Fusion should be limited to the medial metatarsocuneiform joints if full realignment of all five metatarsals can be achieved with this procedure.A review of the literature revealed that corrective tarsometatarsal arthrodesis reproducibly leads to considerable pain reduction and functional improvement with patient satisfaction between 69% and 100%. Favourable prognostic factors are anatomic realignment and limited fusion of the first to third metatarsocuneiform joints.

[Corrective tarsometatarsal arthrodesis for malunion after fracture-dislocation].

ZusammenfassungFehlverheilte Luxationsfrakturen im Lisfranc-Gelenk führen regelhaft zu schmerzhaften Fehlstellungen mit erheblichen Funktionseinschränkungen für die betroffenen Patienten. Die Ursachen liegen zum einen in primär übersehenen, zum anderen in unterschätzten und inadäquat behandelten Verletzungen. Je nach primärer Luxationsrichtung resultiert eine Abduktion oder Adduktion des Vorfußes mit einer begleitenden Platt- oder Hohlfußbildung.Ziel der reorientierenden Arthrodese des tarsometatarsalen Übergangs ist die Wiederherstellung der Achsenverhältnisse und Stabilisierung von chronischen Instabilitäten, insbesondere nach rein ligamentären Verletzungen. Nach Möglichkeit sollte die Arthrodese auf die medialen 3 Strahlen beschränkt bleiben, wenn sich hierdurch auch eine korrekte Ausrichtung der 2 lateralen Strahlen erreichen lässt.Die Korrekturarthrodese führt zu einer deutlichen Beschwerdeminderung und einem erheblichen Funktionsgewinn mit einer Patientenzufriedenheit zwischen 69 und 100% in der Literaturübersicht. Günstige Prognosefaktoren sind die anatomische Achsenkorrektur und die Begrenzung der Fusion auf den I. bis III. Strahl.AbstractMalunited fracture dislocations at the tarsometatarsal (Lisfranc’s) joint regularly lead to painful deformities with severe functional impairment for the affected patients. Malunions result from initially overlooked injuries as well as from misjudged and inadequately treated injuries. Depending on the nature of the primary dislocation, either abduction or adduction of the forefoot will result, accompanied by a planus or cavus deformity.Corrective arthrodesis aims at axial realignment at the tarsometatarsal junction, and elimination of residual instabilities especially after pure ligamentous injuries. Fusion should be limited to the medial metatarsocuneiform joints if full realignment of all five metatarsals can be achieved with this procedure.A review of the literature revealed that corrective tarsometatarsal arthrodesis reproducibly leads to considerable pain reduction and functional improvement with patient satisfaction between 69% and 100%. Favourable prognostic factors are anatomic realignment and limited fusion of the first to third metatarsocuneiform joints.

Histological Analysis of the Structural Composition of Ankle Ligaments

Background: Various ankle ligaments have different structural composition. The aim of this study was to analyze the morphological structure of ankle ligaments to further understand their function in ankle stability. Methods: One hundred forty ligaments from 10 fresh-frozen cadaver ankle joints were dissected: the calcaneofibular, anterior, and posterior talofibular ligaments; the inferior extensor retinaculum, the talocalcaneal oblique ligament, the canalis tarsi ligament; the deltoid ligament; and the anterior tibiofibular ligament. Hematoxylin-eosin and Elastica van Gieson stains were used for determination of tissue morphology. Results: Three different morphological compositions were identified: dense, mixed, and interlaced compositions. Densely packed ligaments, characterized by parallel bundles of collagen, were primarily seen in the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments. Ligaments with mixed tight and loose parallel bundles of collagenous connective tissue were mainly found in the inferior extensor retinaculum and talocalcaneal oblique ligament. Densely packed and fiber-rich interlacing collagen was primarily seen in the areas of ligament insertion into bone of the deltoid ligament. Conclusions: Ligaments of the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments have tightly packed, parallel collagen bundles and thus can resist high tensile forces. The mixed tight and loose, parallel oriented collagenous connective tissue of the inferior extensor retinaculum and the talocalcaneal oblique ligament support the dynamic positioning of the foot on the ground. The interlacing collagen bundles seen at the insertion of the deltoid ligament suggest that these insertion areas are susceptible to tension in a multitude of directions. Clinical Relevance: The morphology and mechanical properties of ankle ligaments may provide an understanding of their response to the loads to which they are subjected.