Common Rodent Flap Models in Experimental Surgery

Background: Flap procedures are widely used in clinical reconstructive surgery. Since ische­mia-associated complications, e.g., wound breakdown or tissue necrosis, are still a great challenge in flap surgery, experimental flap models are widely used to study flap physiology and to evaluate treatment strategies to prevent these complications. Summary: Since rodents in general, and mice and rats in particular, are widely used in experimental flap models, we give an overview of the most common flap models in rodents, including the cremaster flap, the osteomyocutaneous flap, the McFarlane flap, the ear flap, and the dorsal skinfold chamber. Key Messages: Rodent flap models in experimental surgery are manifold and have a long history. These models play an important role in training surgical techniques, understanding flap physiology, defining flap anatomy and vascularity, and developing treatment regimens to prevent the necrosis of ischemically challenged tissue. However, it is important to be aware of the advantages and disadvantages of the single flap models concerning the possible time span of the experiment, the degree of difficulty, and the reproducibility and the translation of the results in humans.

Non-linear optical microscopy and histological analysis of collagen, elastin and lysyl oxidase expression in breast capsular contracture

Background

Capsular contracture is one of the most common complications in surgical interventions for aesthetic breast augmentation or post-mastectomy breast reconstruction involving the use of silicone prostheses. Although the precise cause of capsular contracture is yet unknown, the leading hypothesis is that it is caused by long-term unresolved foreign body reaction towards the silicone breast implant. To authors’ best knowledge, this is the first study that elucidates the presence of lysyl oxidase (LOX)—an enzyme that is involved in collagen and elastin crosslinking within fibrous capsules harvested from patients with severe capsular contracture. It was hypothesized that over-expression of LOX plays a role in the irreversible crosslinking of collagen and elastin which, in turn, stabilizes the fibrous proteins and contributes to the progression of capsular contracture.

Methods

Eight fibrous capsules were collected from patients undergoing capsulectomy procedure, biomechanical testing was performed for compressive Young’s moduli and evaluated for Type I and II collagen, elastin and LOX by means of non-linear optical microscopy and immunohistology techniques.

Results

Observations revealed the heterogeneity of tissue structure within and among the collected fibrous capsules. Regardless of the tissue structure, it has been shown that LOX expression was intensified at the implant-to-tissue interface.

Conclusion

Our results indicate the involvement of LOX in the initiation of fibrous capsule formation which ultimately contributes towards the progression of capsular contracture.

Electronic supplementary material

The online version of this article (10.1186/s40001-018-0322-0) contains supplementary material, which is available to authorized users.

[Lundborg's resection arthroplasty vs. Pyrocarbon spacer (Pyrocardan®) for the treatment of trapeziometacarpal joint osteoarthritis: a two-centre study]

Background Various operative approaches exist for osteoarthritis of the trapeziometacarpal joint. The aim of this two-centre study was to compare the results of Lundsborg's resection arthroplasty with the implantation of the Pyrocardan^® spacer. Patients and methods We treated 20 patients with symptomatic osteoarthritis of the trapeziometacarpal joint in stage III / IV (Eaton-Littler classification). Twelve patients received Lundsborg's resection arthroplasty (centre 1), and in 8 patients a Pyrocardan^® spacer was implanted (centre 2). Both groups were comparable regarding patients´ age, the preoperative pain level, the osteoarthritis stage according to Eaton-Littler, and the duration from the onset of symptoms until surgery. Patient data were retrospectively collected from patient records, and we performed a follow-up examination at least 18 months postoperatively, thereby evaluating the DASH sore, the postoperative time until freedom of symptoms, the pain level according to the visual analogue scale, grip force (Jamar dynamometer), pinch force, and patients' treatment satisfaction (0-10; 10 = highest satisfaction). Results Both groups had a similar length of follow-up with 23.6 ± 5.2 months for the resection group and 26.1 ± 4.0 months for the spacer group. The duration of the operation was 31 ± 5 min for the resection group and 29 ± 7 min for the spacer group (p > 0.05). The DASH score was 21.9 ± 6.2 in the resection group and 18.3 ± 5.0 in the spacer group (p > 0.05). The pain level at the current follow-up was 1.5 ± 0.83 in the spacer group and 1.0 ± 0.74 in the resection group (p > 0.05). The time until freedom of symptoms was significantly shorter in the spacer group with 3.7 ± 1.9 months compared to the resection group with 5.7 ± 3.1 months (p = 0.0001). Grip force and pinch force were not significantly different between both groups. Treatment satisfaction was 9.3 ± 1.6 in the resection group and 7.4 ± 3.0 in the spacer group (p > 0.05). Conclusion Over a follow-up period of 1.5 years, both techniques resulted in a satisfactory usability of the operated hand and a clear reduction of symptoms. The implantation of the Pyrocardan^® spacer seems to have slight advantages regarding a shorter time until freedom of symptoms. However, the implantation of the spacer is associated with additional material costs of a few hundred Euros, which are not incurred in resection arthroplasties. The implantation of the Pyrocardan^® spacer seems to have slight advantages regarding a shorter time until freedom of symptoms.

Postoperative negative pressure therapy significantly reduces flap complications in distally based peroneus brevis flaps: Experiences from 74 cases

BACKGROUND

The distally based peroneus brevis muscle flap is a valuable therapeutic option for coverage of tissue defects around the ankle and the distal lower leg. However, the rate of postoperative flap complications requiring revisional surgery is high due to an impaired venous drainage and oedema formation. The purpose of this study was to evaluate if postoperative negative pressure therapy is able to reduce flap complications.

METHODS

From April 2010 until March 2014, we treated 74 patients with distally based peroneus brevis muscle flaps for defect coverage at the lower leg. In four cases, an osteomuscular composite flap has been used to treat partly stability-relevant bone defects. In 43 cases, negative pressure therapy (75mmHg, continuous) with a circular dressing was initiated after the flap procedure for 7 days. In 31 cases no negative pressure therapy was initiated. We retrospectively analysed those two groups of patients. The primary endpoint was the incidence of flap complications with a need for revision surgery, which were classified in three grades.

RESULTS

The group treated with negative pressure therapy had significantly less flap complications when compared to the control group (p<0.0001). Concerning the single grades of complication, the negative pressure therapy-group had a significantly smaller rate of skin graft necrosis (Grade 1; p=0.014) and partial flap loss (Grade 2; p=0.002) compared to the control group. There were no statistically significant differences concerning complete flap loss (Grade 3) between both groups.

CONCLUSION

Postoperative negative pressure therapy for 7 days reduces flap complications in distally based peroneus brevis flaps.

Microsurgeons do better--tactile training might prevent the age-dependent decline of the sensibility of the hand

Recent data demonstrate that the normal sensibility of the hand seems to be age-dependent with the best values in the third decade and a consecutive deterioration afterwards. However, it is not clear if long-term tactile training might prevent this age-dependent decline. We evaluated sensibility of the hand in 125 surgeons aged between 26 and 75 years who perform microsurgical operations, thereby undergoing regular tactile training. We examined sensibility of the radial digital nerve of the index finger (N3) and the ulnar digital nerve of the small finger (N10) using static and moving two-point discrimination (2PD) tests and compared the results to 154 age-matched individuals without specific long-term tactile training. We found significantly lower static and moving 2PD values for the sixth, seventh, and eighth decade of life in the microsurgery group compared to the control group (p < 0.05). This study demonstrates that long-term tactile training might prevent the known age-dependent decline of the sensibility of the hand.