Biomedical subjects

Gerhard Pierer

Publications and source records attributed to Gerhard Pierer.

15 recordsLinked to original sources

PubMed2006

Reconstruction of the nipple-areola complex: an update.

Along with continuing progress in reconstructive surgery of the breast numerous techniques of nipple-areola reconstruction have been developed. With time and experience some methods have been discredited to historical significance only while others have evolved to widely accepted concepts used by surgeons all over the world, which in turn contributed new ideas and modifications. In addition to those favourite techniques others are reserved as second-line alternatives in specific situations. The principle criterion for a pleasing nipple-areola complex is symmetry regarding several parameters: colour, texture, size, and projection. The purpose of this manuscript is to review and discuss the concepts and techniques of nipple-areola reconstruction that have evolved over the past decades. Furthermore, those principles and techniques are pointed out that fulfil best the criteria of an ideal nipple-areola complex with emphasis on different techniques of breast reconstruction and individual conditions of the patient.

Esthetics↗

PubMed2006

Free fasciocutaneous flaps in the treatment of chronic osteomyelitis of the tibia: a retrospective study.

The efficacy of free fasciocutaneous flaps for the treatment of chronic osteomyelitis of the tibia was evaluated in a retrospective study. A series of 14 patients is reported who underwent soft-tissue reconstruction using different free fasciocutaneous flaps after radical debridement. Radical debridement and microvascular reconstruction were performed in two operative steps. The mean duration of disease was 14 years (range: 6 months to 37 years). At a mean follow-up of 31.4 (12 to 52) months, there was no evidence of recurrence of osteomyelitis. This retrospective study validates that fasciocutaneous flaps can be used for microsurgical soft-tissue reconstruction after radical debridement in the treatment of chronic osteomyelitis. The introduction of free fasciocutaneous flaps has challenged the dictum of the therapy of chronic osteomyelitis with muscle flaps.

Adult↗

PubMed2006

Anatomical basis and clinical application of the infragluteal perforator flap.

BACKGROUND: When selecting flaps for coverage of pressure ulcers of the sacrum and perineal region in paraplegic patients, long-term high recurrence rates should be considered. Therefore, the authors developed an infragluteal perforator flap to avoid "burning bridges" for future reconstruction. METHODS: Infragluteal perforator flaps were dissected in five fresh human cadavers to define the anatomy of the cutaneous branches of the descending branch of the inferior gluteal artery and cluneal nerves and define anatomical landmarks for clinical application. In a series of 13 paraplegic patients, the authors used perforator-based flaps (additional skin bridge) to cover four perineal ulcers and one sacral ulcer and perforator flaps to cover six perineal and two sacral ulcers. Donor sites were closed by direct approximation. RESULTS: Twelve of 13 flaps healed uneventfully. In all cadaver and clinical dissections, one or two cutaneous branches of the descending branch of the inferior gluteal artery and one or two cluneal nerves were found at the lower border of the gluteus maximus muscle supplying the infragluteal perforator flap. These direct cutaneous branches allowed dissection of inferior gluteal perforator flaps with improved flap mobility compared with the perforator-based flaps. The descending branch of the inferior gluteal artery could always be spared for future flaps. CONCLUSIONS: The infragluteal perforator flap is a versatile and reliable flap for coverage of ischial and sacral pressure sores. It can be designed as a perforator-based or perforator flap and could provide a sensate flap in ambulatory patients. Donor-site morbidity is minimal, and options for future flaps of the gluteal and posterior thigh region are preserved.

Adult↗

PubMed2006

High magnification assessment improves complete resection of facial tumors.

Complete resection with minimal sacrifice of healthy skin is the goal in treatment of basal cell carcinoma (BCC) of the face. In a randomized trial, preoperative assessment of tumor extension with the Varioscope, a combination of microscope and loupe glasses with strong illumination and a maximal magnification of 7X, was compared with tumor assessment without. Forty consecutive, primary BCC of the solid subtype of the face were randomly assigned to the study groups. Preoperative tumor marking was done by a surgeon not involved in tumor resection, reconstruction, and patient follow-up. All BCC marked with the high magnification were completely excised in the first resection. In the control group, frozen section was used in 12 tumors and permanent section in the remaining 8. The first resection did not yield tumor-free margins as assessed in the frozen section analysis in 3 tumors. In 2 of 8 tumors not supported by frozen section analysis, incomplete excision was detected, and 1 case of false-negative frozen section analysis occurred. In conclusion, the use of high magnification resulted in a trend towards reduction of positive tumor margins in the subgroups that were performed under either intraoperative frozen section or permanent, fixed section histology control, and a significant reduction in tumor-positive margins of all first resections. This was attributed to enhanced preoperative tumor visualization by high (7X) loupe magnification and additional lighting.

Aged↗

PubMed2006

Precultivation of engineered human nasal cartilage enhances the mechanical properties relevant for use in facial reconstructive surgery.

OBJECTIVE: To investigate if precultivation of human engineered nasal cartilage grafts of clinically relevant size would increase the suture retention strength at implantation and the tensile and bending stiffness 2 weeks after implantation. SUMMARY BACKGROUND INFORMATION: To be used for reconstruction of nasal cartilage defects, engineered grafts need to be reliably sutured at implantation and resist to bending/tension forces about 2 weeks after surgery, when fixation is typically removed. METHODS: Nasal septum chondrocytes from 4 donors were expanded for 2 passages and statically loaded on 15 x 5 x 2-mm size nonwoven meshes of esterified hyaluronan (Hyaff-11). Constructs were implanted for 2 weeks in nude mice between muscle fascia and subcutaneous tissue either directly after cell seeding or after 2 or 4 weeks of preculture in chondrogenic medium. Engineered tissues and native nasal cartilage were assessed histologically, biochemically, and biomechanically. RESULTS: Engineered constructs reproducibly developed with culture time into cartilaginous tissues with increasing content of glycosaminoglycans and collagen type II. Suture retention strength was significantly higher (3.6 +/- 2.2-fold) in 2-week precultured constructs than in freshly seeded meshes. Following in vivo implantation, tissues further developed and maintained the original scaffold size and shape. The bending stiffness was significantly higher (1.8 +/- 0.8-fold) if constructs were precultured for 2 weeks than if they were directly implanted, whereas tensile stiffness was close to native cartilage in all groups. CONCLUSION: In our experimental setup, preculture for 2 weeks was necessary to engineer nasal cartilage grafts with enhanced mechanical properties relevant for clinical use in facial reconstructive surgery.

Adult↗

PubMed2005

Differentiation-dependent up-regulation of BMP-2, TGF-beta1, and VEGF expression by FGF-2 in human bone marrow stromal cells.

BACKGROUND: Bone tissue formation by bone marrow stromal cells may be supported and enhanced by multiple growth factors, particularly in cases of a compromised local microenvironment. In this study, the authors hypothesized that fibroblast growth factor (FGF)-2 can stimulate the production by human bone marrow stromal cells of osteogenic [i.e., bone morphogenetic protein (BMP)-2 and transforming growth factor (TGF)-beta1] and angiogenic [i.e., vascular endothelial growth factor (VEGF)] factors. METHODS: Human bone marrow stromal cells from six donors were expanded for two passages (expansion phase) and subsequently cultivated in osteogenic medium containing ascorbic acid, beta-glycerophosphate, and dexamethasone (differentiation phase). After each phase, cells were transferred into serum-free medium with or without FGF-2 at different concentrations and for different times, and the expression of BMP-2, TGF-beta1, and VEGF was quantified at the mRNA level by real-time quantitative reverse-transcriptase polymerase chain reaction. The amounts of TGF-beta1 and VEGF released in the culture medium were assessed using enzyme-linked immunosorbent assay kits and normalized to the DNA content. RESULTS: In response to 5 ng/ml FGF-2 for 24 hours, the mRNA expression of VEGF increased at both culture phases (up to 6.1 fold), whereas that of BMP-2 and TGF-beta1 significantly increased only after the expansion (3.1-fold) or differentiation phase (2.1-fold), respectively. Similar trends were observed in the amounts of proteins measured in the culture medium. CONCLUSIONS: The authors' results indicate that FGF-2 up-regulates the expression of BMP-2, TGF-beta1, and VEGF in human bone marrow stromal cells, in a pattern dependent on the cell-differentiation stage. These findings prompt for in vivo investigations on the delivery of FGF-2 for the temporally/functionally regulated enhancement of bone marrow stromal cell-based bone induction.

Bone Marrow Cells↗

PubMed2005

Therapeutic alternatives in nonunion of hamate hook fractures: personal experience in 8 patients and review of literature.

Symptomatic nonunion frequently results after conservative treatment of hamate hook fractures, emphasizing the need of appropriate surgical strategies. A retrospective analysis of 8 patients with nonunions treated by fragment excision or open reduction and internal fixation (ORIF) at 3 centers was performed. The literature was reviewed for treatment options, as bone grafting and low-intensity pulsed ultrasound. Although fragment excision is advocated as the "gold standard" in nonunion, reports on functional results are controversial, and recent anatomic and biomechanical studies of the hook challenge this opinion. In our patients, complete relief of symptoms and comparable functional results were observed after ORIF or fragment excision. Bone grafting could supplement ORIF in selected cases. Low-intensity pulsed ultrasound may evolve as a conservative treatment option. Several alternatives to hook excision are available aiming at complete anatomic and functional recovery of hamate hook nonunion. Further experience is needed before general recommendations can be formulated.

Adult↗

PubMed2004

Use of a combined pedicled toe fillet flap.

We report the use of a double toe fillet flap combined with reconstruction of the joint capsule of the metatarsal proximal phalanx (MP) in a diabetic patient with a chronic persistent deep plantar ulcer and an avulsed third MP joint. Not only was the soft tissue defect dealt with, but also the stability of the MP joint was increased by the vascularised extensor tendon provided by the pedicled toe fillet flap.

Aged↗

PubMed2003

Retrograde arterialized venous flap: an experimental study.

An experimental model was established to study circulation in retrograde arterialized venous flaps (RAVF). Venous flaps measuring 7 x 4 cm with a matching venous system were harvested from both forearms of 10 fresh human cadavers. In each trial, both flaps were simultaneously perfused with heparinized human blood driven by a pulsatile circulation model. In each trial there was one flap with retrograde perfusion, and one flap with antegrade perfusion. Clinical assessment, measurement of outflow, and angiographic examination with digitally assisted assessment after 3 h of perfusion showed better results for retrograde perfusion in 8 of the 10 trials. This study indicates that blood circulation in the periphery of arterialized venous flaps can be enhanced by retrograde arterialization.

Angiography↗

PubMed2003

Vacuum-assisted wound closure for cheaper and more comfortable healing of pressure sores: a prospective study.

Pressure sores are a common complication of patients with spinal injuries. The vacuum-assisted closure technique is widely used to induce and promote wound healing. We tested our clinical impression that pressure sores healed faster with vacuum-assisted closure, and compared it with the traditional wet-to-dry/wet-to-wet technique with gauze soaked in Ringer's solution changed three times a day. Consecutive patients with pressure sores were entered into the study. Two randomised groups of 11 patients each with pressure sores of the pelvic region were included. We found no difference in time to reach 50% of the initial wound volume between the two methods. The vacuum-assisted group took a mean (SD) of 27 (10) days and the traditional group 28 (7) days. The two methods were equally effective in forming granulation tissue, so one can profit from the other advantages of the vacuum-assisted treatment (reduced costs and improved comfort) knowing that the effect on the formation of granulation tissue is as good as with the traditional treatment.

Adult↗

PubMed2003

Influence of nerve stump transplantation into a vein on neuroma formation.

The objective of this animal study was to investigate the influence of nerve stump transposition into a vein on neuroma formation. In 24 rats the femoral nerve was severed and the proximal nerve stump was transposed into the lumen of the femoral vein on one side. On the other side, the nerve was severed and left in place. The distal nerve stump was shortened to knee level on both sides. In group 1, the bloodstream was released; in group 2, the segment of the femoral vein containing the nerve stump was excluded from circulation. Histological assessment was performed 8 months later. There were significant differences between the treatment and control sides with respect to neuroma size, endoneural architecture, neural-tissue-to-connective-tissue ratio, and myelination of axons. These data suggest that nerve transposition into a vein could inhibit the formation of classic neuroma.

Anastomosis, Surgical↗

PubMed2003

Reconstruction of combined defects of the Achilles tendon and the overlying soft tissue with a fascia lata graft and a free fasciocutaneous lateral arm flap.

A new approach to reconstruction of the Achilles tendon and overlying soft tissue is presented. A fascia lata graft is used to reconstruct the tendon and is enwrapped by the fascia that is included in a fasciocutaneous lateral arm flap. Five patients were treated with this technique; three of them after surgical Achilles tendon repair, rerupture, and consecutive infection, one after a full-thickness burn with loss of the tendon and one with a history of ochronosis and necrosis of the whole tendon and overlying soft tissue. There were no anastomotic complications and all flaps healed primarily. Functional evaluation with the Cybex II dynamometer was done at least 49 months after reconstruction. A good functional and cosmetic result was obtained in all patients and donor site morbidity was acceptable. These results are well within the results of other surgical treatment options reported in the literature.

Achilles Tendon↗

PubMedDate not supplied

New posterior auricular perichondrial cutaneous graft for stable reconstruction of nasal defects.

The perichondrial cutaneous graft (PCCG), a reliable composite graft that provides stability, is routinely harvested from the anterior conchal bowl. This established PCCG was simplified by using the less conspicuous posterior auricular donor site, which can be closed without the need of cartilage resection for reconstruction with a postauricular interpolated skin island. Patients with basal cell carcinoma of the nose underwent reconstruction of the nose with a PCCG if parts of the tip cartilage or the fibrofatty tissue were resected. The defect surface area was assessed with a template. Follow-up evaluation included assessment of graft survival, donor-site morbidity, nostril stability, and aesthetic outcome. Of the 14 patients included in the study, whose average defect sizes were 2 cm2 (ala) and 2.5 cm2 (tip), 79% showed primary complete healing. Nostril stability was symmetrical 6 months postoperatively, and no contractions or depressed contour had occurred. In one case, a hyperpigmented area resulted in a slightly imperfect color match. All the donor sites healed without deformity or destabilization of the ear. With the use of this new posterior auricular donor site for graft harvest, functional, stable, and aesthetic reconstruction of the nose can be achieved. The graft- and donor-site morbidity rates are very low, and the results are fully satisfying.

Aged↗

PubMedDate not supplied

Laser surface scanning analysis in reconstructive rhytidectomy.

The implementation of laser surface scanning to assess facial symmetry after unilateral face-lift procedures used to reconstruct defects after skin tumor resection is presented. Six patients who had undergone defect reconstruction with a flap raised from the subcutaneous plane were included in the study. Immediate postoperative photographic evaluation confirmed facial asymmetry because of unilateral skin tension. After a minimum follow-up period of 1 year, photographic and laser surface scanning analysis showed restored facial symmetry. In conclusion, laser surface scanning is a promising technology for objectifying results obtained and could be implemented for evaluation of the immediate and long-term effects from rhytidectomy procedures. Subcutaneous flaps without duplication or resection of the superficial musculoaponeurotic system are ideal for unilateral procedures because facial symmetry is restored after 1 year.

Aged↗

PubMedDate not supplied

Cell yield, proliferation, and postexpansion differentiation capacity of human ear, nasal, and rib chondrocytes.

Human ear, nasal, and rib chondrocytes were compared with respect to their suitability to generate autologous cartilage grafts for nonarticular reconstructive surgery. Cells were expanded for two passages in medium containing 10% fetal bovine serum without (control) or with transforming growth factor beta(1) (TGF-beta(1)), fibroblast growth factor 2 (FGF-2), and platelet-derived growth factor bb (PDGF-bb) (TFP). Expanded cells were cultured as three-dimensional pellets in chondrogenic serum-free medium containing insulin, dexamethasone, and TGF-beta(1). Chondrocytes from all three sources were successfully isolated, increased their proliferation rate in response to TFP, and dedifferentiated during passaging. Redifferentiation by ear and nasal, but not rib, chondrocytes was enhanced after TFP expansion, as assessed by the significant increase in glycosaminoglycan (GAG)/DNA content and collagen type II mRNA expression in the resulting pellets. TFP-expanded ear and nasal chondrocytes generated pellets of better quality than rib chondrocytes, as assessed by the significantly higher GAG/DNA content and collagen type II mRNA expression, and by the relative stain intensities for GAG and collagen types I and II. In conclusion, postexpansion cell yields suggest that all three sources investigated could be used to generate autologous grafts of clinically relevant size. However, ear and nasal chondrocytes, if expanded with TFP, display superior postexpansion chondrogenic potential and may be a preferred cell source for cartilage tissue engineering.

Adolescent↗