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Biomedical subjects

Hans Zwipp

Publications and source records attributed to Hans Zwipp.

At least 19 recordsLinked to original sources
PubMed2007

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

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.

Animals↗
PubMed2006

Coating of titanium implants with collagen, RGD peptide and chondroitin sulfate.

Coating of orthopaedic implants with extracellular bone matrix components was performed to enhance bone healing. Titanium pins of 0.8mm diameter were coated with type I collagen (Ti/Coll), RGD peptide (Ti/RGD) or type I collagen and chondroitin sulfate (Ti/Coll/CS). Uncoated pins (Ti) served as control. The pins were inserted as intramedullary nails into the tibia of male adult Wistar rats. Six specimens of each group were retrieved at 4, 7, 14 and 28 days. All implants healed uneventfully without adverse reactions. ED 1-positive macrophages appeared in higher numbers around Ti/RGD at day 4 and around Ti at day 14 after implantation (p < 0.05). TRAP-positive osteoclasts and precursors were abundant around Ti/Coll/CS at day 7 (p < 0.05). A significant increase in osteopontin-positive osteoblasts was seen around Ti/Coll/CS implants at days 7 and 14, and around Ti/RGD at day 14 (p < 0.05). At day 28, 62% of Ti, 76% of Ti/Coll, 85%* of Ti/RGD and 89%* of Ti/CoIl/CS (*p < 0.05) implants were covered with newly formed lamellar bone. The addition of extracellular matrix components significantly enhances bone remodelling in the early stages of bone healing around Ti implants, eventually leading to increased new bone formation at the implant surface after 4 weeks.

Animals↗
PubMed2006

[Modified Evans osteotomy for the operative treatment of acquired pes planovalgus].

OBJECTIVE: Restoration of the longitudinal arch of the foot and reorientation of the hindfoot for painful decompensating flatfoot (pes planovalgus) due to posterior tibial tendon dysfunction. INDICATIONS: Passively correctable, painful pes planovalgus of various etiologies such as stage II flatfoot as graded by Johnson & Strom mostly due to degeneration of the posterior tibial tendon in stage II-III as described by Jahss. CONTRAINDICATIONS: Fixed pes planovalgus, osteoporosis of the calcaneus, advanced degenerative arthritis of the subtalar, talonavicular or calcaneocuboid joints. SURGICAL TECHNIQUE: Transverse osteotomy of the anterior process of the calcaneus approximately 1.5 cm proximal of and parallel to the calcaneocuboid joint. Lengthening of the lateral column using the sandwich technique by the interposition of one to two autologous, tricortical bone grafts, which are structured to straighten the hindfoot and to move it toward neutral position. If the technique is performed correctly, the talus and the calcaneus are in alignment. When the talar head is externally rotated and the calcaneus is moved toward varus, this results in axial alignment of the abducted forefoot and straightening of the collapsed longitudinal arch of the foot. RESULTS: Between June 1995 and March 2003, 21 patients with stage II painful pes planovalgus as described by Johnson & Strom underwent a modified Evans osteotomy. In one case an arthrodesis of the first tarsometatarsal joint was carried out, and in four cases a lengthening of the gastrocnemius muscle according to Strayer. A replacement of the insufficient posterior tibial tendon was not necessary in any of the cases. With respect to complications one wound edge necrosis and one nonunion were seen. 15 patients (eleven women, four men, average age 54 years) were followed up for an average of 48 months (12-81 months) postoperatively. The Maryland Foot Score improved significantly from 49.6 points preoperatively to 87.8 points postoperatively (p < 0.01). In the cases of one-sided deformity the foot axes in the weight-bearing radiographs were corrected to being close to the physiologic values of the opposite side.

Adult↗
PubMed2006

The percutaneous suture of the Achilles tendon with the Dresden instrument.

OBJECTIVE: Minimally invasive suture of the torn Achilles tendon without opening the rupture site, reduction in the risk of a sural nerve lesion, and optimization of stump apposition. INDICATIONS: Fresh Achilles tendon rupture. CONTRAINDICATIONS: Chronic achillodynia, local corticoid injections, immunosuppressive therapy, old Achilles tendon ruptures, rerupture. SURGICAL TECHNIQUE: Suture of the Achilles tendon with a special instrument via a skin incision proximal to the rupture, without opening the peritenon or the rupture site, whereby the suture in the area of the proximal Achilles tendon is placed in the layer between the lower-leg fascia and the peritenon with the threads running in a paratendinous direction. RESULTS: From January 1, 2000 to December 31, 2003, 61 patients with 62 Achilles tendon ruptures were sutured using the percutaneous technique with the Dresden Instrument. No sural nerve lesions and only two reruptures (3.2%) were observed. In one patient (1.6%) a superficial late infection occurred after 8 weeks, when the tendon was already healed. Of 47 patients with a follow-up time of at least 1 year, 39 with 40 Achilles tendon ruptures were followed up (83%). According to the criteria of Trillat & Mounier-Kuhn, the result was very good in 62% and good in 30%. On the AOFAS Score, an average of 96 points (78-100 points) was achieved. 78% of the patients assessed the result of the treatment as very good and 20% as good.

Achilles Tendon↗
PubMed2006

Reconstruction after talar fractures.

Malunited and nonunited talar fractures cause significant disability. Distinction between partial and total avascular necrosis (AVN) determines the choice of treatment. Patients who have minimal or no AVN and well-preserved joint cartilage may be amenable to corrective osteotomy through the malunited fracture or removal of the pseudoarthrosis. Secondary reconstruction with joint preservation leads to considerable functional improvement in painful talar malunions and nonunions in reliable patients. If symptomatic arthritis is present, arthrodeses and correction of deformity through the fusion or with additional osteotomies provide predictable results, although they do not restore normal foot function. Fusions should be limited to the affected joint. If the subtalar joint shows severe arthritic changes, every attempt should be made to salvage the ankle and talonavicular joints.

Fracture Healing↗
PubMed2005

Osteocalcin enhances bone remodeling around hydroxyapatite/collagen composites.

The effect of osteocalcin (OC), an extracellular bone matrix protein, on bone healing around hydroxyapatite/collagen composites was investigated. Cylindrical nanocrystalline hydroxyapatite implants of 2.5-mm diameter containing 2.5% biomimetically mineralized collagen type I were inserted press-fit into the tibial head of adult Wistar rats. To one implant group, 10 mug/g OC was added. Six specimens per group were analyzed at 2, 7, 14, 28, and 56 days. After 14 days, newly formed woven bone had reached the implant surface of the OC implants whereas a broad fibrous interface could still be observed around controls. Woven bone was formed directly around both implant groups after 28 days and had been replaced partially by lamellar bone around the OC implants only. No significant differences in total bone contact were seen between both groups after 56 days. The higher number of phagocytosing cells and osteoclasts characterized immunohistochemically with ED1, cathepsin D, and tartate-resistant alkaline phosphatase around the OC implants at the early stages of bone healing suggests an earlier onset of bone remodeling. The earlier and increased expression of bone-specific matrix proteins and multifunctional adhesion proteins (osteopontin, bone sialoprotein, CD44) at the interface around the OC implants indicates that OC may accelerate bone formation and regeneration. This study supports the observations from in vitro studies that OC activates both osteoclasts and osteoblasts during early bone formation.

Animals↗
PubMed2005

[Ankle arthrodesis after failed joint replacement].

UNLABELLED: Report of four patients. OBJECTIVE: Restoration of a painless gait through ankle arthrodesis after failed total ankle replacement. INDICATIONS: Loosened or infected total ankle replacement. CONTRAINDICATIONS: Poor general health. Absent patient compliance. SURGICAL TECHNIQUE: Removal of total joint components. Filling of the defect with tricortical bone grafts harvested from the ipsilateral iliac crest and internal fixation. In instances of suspected infection a two-stage procedure is recommended, the first stage consisting of a removal of the components, a meticulous debridement, and filling of the defect with gentamycin-laden PMMA beads. Second stage: arthrodesis. RESULTS: The goal of surgery was reached without complications in two out of four patients. An absence of bony bridging was noted in the fourth patient after 9 months. A revision adding cancellous bone grafts and resorting to an intramedullary fixation led to a success.

Adult↗
PubMed2005

[Ankle arthrodesis with four cancellous lag screws].

OBJECTIVE: Arthrodesis of the ankle at 90 degrees and perfect axial alignment for restoration of a painless function. Early functional postoperative care. INDICATIONS: Painful posttraumatic or idiopathic osteoarthritis of the ankle either unresponsive to conservative measures or where these measures are not expected to be successful. Posttraumatic malalignment of the ankle, paralysis or instability, that cannot be improved or eliminated by joint-preserving measures. Joint destruction after infection. Failure of total joint replacement. CONTRAINDICATIONS: Acute osteitis. Poor skin or soft-tissue conditions. Severe peripheral arterial occlusive disease. SURGICAL TECHNIQUE: Anterior approach, judicious resection of the remaining articular cartilage. Freshening of the zones of sclerosis. Preservation of the anatomic shape of the mortise. Correction of malalignments in the sagittal and frontal planes and placement of the talus in line with the tibial axis. Tibiotalar stabilization with four 7.3-mm self-cutting cannulated cancellous lag screws or with four 6.5-mm cancellous lag screws. RESULTS: Between January 1, 1994 and December 31, 1998 this technique was performed in 50 ankles of 48 patients. 40 patients could be followed up for an average of 5.6 years (4.8-7.6 years). No serious complications. The average compensatory movement of the Chopart joint amounted to 26 degrees . Osteoarthritis of the subtalar joint was seen in 13%, and of the talonavicular joint in 12.5% of patients. Preexisting osteoarthritis of these joints remained in general unchanged. The AOFAS Score was assessed pre- and postoperatively. Preoperatively, 17.5% of patients showed a satisfactory and 82.5% a poor score. Postoperatively, 52.5% had an excellent, 30% a good, 10% a satisfactory, and 7.5% a poor outcome.

Adult↗
PubMed2005

Anatomical reconstruction of malunited talus fractures: a prospective study of 10 patients followed for 4 years.

BACKGROUND: Malunions or nonunions after displaced talar fractures cause significant disability. Salvage procedures such as corrective arthrodesis do not restore normal foot function. METHODS: Between 1994 and 2002, we treated 10 patients (aged 15-50 years) who had painful malunions with secondary anatomical reconstruction, at a mean of 1 year after sustaining displaced fractures of the talar body or neck. 5 patients were classified as type I (malunion and/or residual joint displacement), 2 as type II (nonunion with displacement) and 3 as type III (malunion with partial avascular necrosis, AVN). Correction was by an osteotomy through the malunited fracture or removal of the pseudarthrosis. Internal fixation was achieved with screws and additional bone grafting if necessary. RESULTS: No wound healing problems or infections were seen. Solid union was obtained without redislocation in all cases, with no signs of development or progression of AVN. At a mean of 4 (1-8) years after reconstruction, all patients were satisfied with the result--except one patient who required ankle fusion 8 years after reconstruction. The mean AOFAS Ankle Hindfoot Score increased from 38 to 86 (p < 0.001). INTERPRETATION: Secondary anatomical reconstruction with joint preservation leads to considerable functional improvement in painful talar malunions. Partial AVN does not preclude good to excellent functional results. The quality of the bone stock and joint cartilage (rather than the time from injury) appears to be important for the choice of treatment.

Adolescent↗
PubMed2004

Arthrodesis of the ankle joint.

Arthrodesis of the ankle that uses lag screws for internal fixation is a safe and biomechanically stable method to obtain a solid ankle fusion; it generates good to excellent results in most patients. Prompt bone healing can be expected and allows a functional rehabilitation with full weight bearing. The surgical technique can be simplified further when using cannulated screws. Malalignment hazards while doing the ankle fusion are minimized by respecting the shape of the ankle mortise because no osteotomy of the lateral malleolus is performed. Generally, removal of the implanted material is not necessary. Major complications such as infection, stress fractures, or nonunion were not seen in our series. A meticulous resection of all cartilage and sclerotic bone and an atraumatic surgical technique are essential for preventing those major complications. The need for revision surgery is minimized by correction of talar malalignment, fusion with the ankle in a 90 degrees position, and preoperative evaluation of the subtalar joint. External fixation methods are used in cases of osteitis, osteonecrosis, osteoporosis, and poor soft tissue conditions. With severe loss of bone stock at the distal tibia, stability can be achieved by using an intramedullary nail for ankle fusion.

Ankle Joint↗
PubMed2004

The role of external fixation in acute ankle trauma.

The use of external fixation methods has become increasingly popular throughout the past decade in the treatment of tibial pilon fractures to prevent the dreaded soft tissue complications after high velocity injuries. A variety of methods has been proposed, including ankle-spanning half-pin frames; circular (Ilizarov) frames with tensioned wires; or hybrid frames, either as the sole treatment or, more frequently, in conjunction with limited internal screw fixation. External fixation also has a role in staged protocols as a primary tool for reduction and preliminary fixation until soft tissue consolidation makes internal fixation feasible. Although good to excellent results are reported in a high percentage of cases in most studies and infection rates have dropped to less than 10%, even for high velocity injuries with considerable soft tissue compromise, no single form of treatment seems to be suitable for all types of pilon fractures. Major concerns after external fixation are the development of pin track infections, malunions or nonunions, and the danger of imperfect reduction of the articular surface. Staged protocols that are based on the severity of the fracture and soft tissue injury are likely to play a major role in the future treatment of pilon fractures. In the treatment of acute malleolar fractures, ankle-spanning external fixation is reserved for fractures with considerable soft tissue compromise, open fractures, or compartment syndrome as a temporary transfixation until internal fixation becomes feasible.

Acute Disease↗
PubMed2004

Calcaneus fractures: facts, controversies and recent developments.

The management of calcaneus fractures and their associated soft tissue injuries are challenging tasks for the surgeon. Open reduction and stable internal fixation with a lateral plate and without joint transfixation has been established as a standard therapy for displaced intra-articular fractures with good to excellent results in two-thirds to three-quarters of cases in larger clinical series. Bone grafting appears not useful in the vast majority of cases. Anatomical reduction of joint congruity and the overall shape of the calcaneus are important prognostic factors. The quality of joint reduction should be reliably proven intra-operatively either with Brodén views, high-resolution fluoroscopy or open subtalar arthroscopy. Treatment results are adversely affected by open fractures, delayed reduction after more than 14 days and individual risk factors such as high body mass index and smoking. The extended lateral approach respects the neurovascular supply to the heel and allows a good exposure of the fractured lateral wall, and the subtalar and calcaneocuboid joints in most fractures. In selected fracture patterns percutaneous screw fixation, possibly with arthroscopic control, is a good alternative. Open fractures, compartment syndrome and fractures with severe soft tissue compromise are treated as emergency cases. Early, stable soft tissue coverage appears promising in treating complex open fractures. The benefits of newly developed plate designs and subtalar arthrolysis at the time of hardware removal remains to be proven in further studies. Calcaneal malunions after conservative therapy of displaced fractures are disabling conditions that can be treated successfully with a staged protocol according to the type of deformity. Treatment options include lateral wall decompression, subtalar in situ, or corrective, arthrodesis and calcaneal osteotomy along the former fracture line.

Biomechanical Phenomena↗
PubMed2004

Integral classification of injuries (ICI) to the bones, joints, and ligaments--application to injuries of the foot.

The integral classification of injuries (ICI) is a very logical, descriptive classification of fractures and dislocations of the human skeleton. By enumerating all 28 foot bones in relation to the three anatomical and functional regions of the foot, ie, hindfoot (81), midfoot (82), forefoot (83), from proximal to distal, and by introducing lowercase letters for the joints of the foot skeleton,the localization of the injury can be described precisely. The uppercase A defines extra-articular, B describes intra-articular and C is for fracture dislocations. By introducing the uppercase D, different dislocations can be described. By using additional lowercase Greek letters, the direction of a dislocation can be coded. For simple 'everyday' use, a fracture of the calcaneus(81.2) involving three joints can be described as a B3-fracture. For scientific or database coding purposes, one can describe in square brackets which joints or segments are involved and how they are injured in relation to three different subgroups representing first the tissue (bone, cartilage, capsule, and ligaments),second the kind of injury (three graduations of fracture, cartilage, or ligament damage), and third (three graduations) the extent of the dislocation or displacement. Following ten conventions, a complex foot trauma can be coded as precisely as a simple dislocation of the big toe.

Calcaneus↗
PubMed2004

Calcaneal fractures--open reduction and internal fixation (ORIF).

Although pioneers such as Leriche in 1921 [5] and Judet et al in 1954 [4] introduced screw or plate fixation of the broken calcaneus, surgical treatment using open anatomical reduction and stable internal osteosynthesis only commenced at the start of the 1980s. This treatment was made possible by the introduction of new imaging methods such as CT which allowed better detection of the fracture pathology and provided the basis for new surgical strategies. Since the start of the 1990s, various anatomically shaped steel and titanium calcaneal plates have been available. The Foot and Ankle Expert Group of the AO Foundation together with Synthes USA developed an anatomically shaped interlocking calcaneal plate, which has been available in steel since 2002, and a titaniummolybdenum(15%) alloy version (Mathys) since November 2003. The latter is now being tested clinically in our unit.

Adolescent↗
PubMed2004

Minimally-invasive treatment of calcaneal fractures.

Percutaneous reduction methods play an important role in the management of calcaneal fractures with severe soft tissue compromise, particularly open fractures, and they offer a treatment alternative in patients with local or systemic contraindication to open reduction. Percutaneous reduction by pin leverage (Westhues or Essex-Lopresti maneuver) followed by minimally invasive screw fixation is a treatment option that yields good to excellent results in tongue-type fractures with posterior facet displacement as a whole (Sanders-type IIC). This method can be applied to selected Sanders-type IIA or IIB fractures if the quality of joint reduction is controlled arthroscopically. Although some authors have expanded the use of percutaneous reduction by traction, leverage, and compression with subsequent K-wire or screw fixation with remarkable results, the uniform application of percutaneous methods to all intra-articular calcaneus fractures is critical. Inadequate joint reduction and redislocation of the fragments in highly unstable fractures may occur in a considerable percentage of cases. Prolonged transfixation of the subtalar and calcaneocuboid joints is strongly discouraged, because functional aftertreatment is an important part of the rehabilitation after calcaneal fractures.

Adult↗
PubMed2004

Metatarsal fractures.

Metatarsal fractures are relatively common and if malunited, a frequent source of pain and disability. Nondisplaced fractures and fractures of the second to fourth metatarsal with displacement in the horizontal plane can be treated conservatively with protected weight bearing in a cast shoe for 4-6 weeks. In most displaced fractures, closed reduction can be achieved but maintenance of the reduction needs internal fixation. Percutaneous pinning is suitable for most fractures of the lesser metatarsals. Fractures with joint involvement and multiple fragments frequently require open reduction and plate fixation. Transverse fractures at the metaphyseal-diaphyseal junction of the fifth metatarsal ("Jones fractures") require an individualized approach tailored to the level of activity and time to union. Avulsion fractures of the fifth metatarsal bone are treated by open reduction and tension-band wiring or screw fixation if displaced more than 2 mm or with more that 30% of the joint involved. The metatarsals are the most common site of stress fractures, most of which are treated nonoperatively. Symptomatic posttraumatic deformities need adequate correction, in most cases by osteotomy across the former fracture site.

Fractures, Bone↗
PubMed2004

Coating of titanium implants with type-I collagen.

PURPOSE: Type-I collagen, the major structural protein in bone, has beneficial properties regarding bone regeneration. Little is known about the potential effects of collagen coating on orthopedic implants. METHODS: 3 to 6 microg/cm2 of lyophilized type-I collagen was absorbed on titanium rods. Six coated and uncoated pins of 0.9 mm diameter were inserted into the tibia of adult male Wistar rats for 1, 2, 4, 7, 14, and 28 days. Specimens were embedded in methacrylate-based Technovit 9100N resin. From one portion cutting and grinding sections were obtained. The implant was removed from the other half that was depolymerized, sectioned, and mounted for immunohistochemistry. RESULTS: At day 4, the interface around the collagen-coated implants displayed a granulation tissue with higher numbers of cathepsin D-positive mononucleated cells compared to the uncoated implants (p<0.05). Active osteoblasts, reactive for osteopontin, were increased around the collagen-coated pins at day 4 and 7 (p<0.01). After 28 days of implantation, direct bone contact averaged 74.9% around the collagen-coated implants and 62.1% around uncoated implants (NS). The amount of newly formed bone averaged 76.3% around the collagen-coated pins and 67.8% around the uncoated pins (NS). The histomorphometric findings were confirmed by SRmicroCT in two specimens. CONCLUSIONS: The earlier observation of mononuclear phagocytozing cells and the earlier and higher expression of bone-specific matrix proteins suggest an increased early bone remodeling around titanium pins through collagen coating. A tendency towards increased bone formation was observed around the coated implants.

Animals↗