The ethics committee of Ludwig-Maximilians University, Munich / Germany approved the prospective, randomized, case-control evaluation of the gluteal wound healing process of patients having undergone enucleation and primary DFG implantation as performed in this trial (vote number 19–093, registration date 10/04/2019) at the oculoplastic department of the eye clinic of Ludwig-Maximilians University, Munich / Germany after evaluation and approval of the study protocol. The study is in accordance with the Declaration of Helsinki. Written informed consent was obtained from all patients prior to inclusion into the study. The study is registered in the Deutsches Register Klinischer Studien (www.drks.de; number DRKS00023111, registration date 05/10/2020).
Patient eligibility criteria included patients having undergone DFG harvesting over 18 years of age. Exclusion criteria were skin alterations as well as known allergic reactions to tape.
The primary endpoint of the study was evaluation of the gluteal scar (length, color, prominence, indentation, visibility) 4–6 weeks post surgery as well as 3 months later. The secondary endpoint was patient content regarding functionality and cosmesis.
Sample size was calculated as per the expected number of surgeries over a period of two years. Originally, inclusion of 50 patients was planned (5 sets of 10 numbers evenly randomized to the case and control groups by the Research Randomizer software (https://www.randomizer.org/). Numbers were sealed in sequentially numbered envelopes in order to conceal the sequence until interventions were assigned.
The patients in the case group locally applied kinesiotapes (hypo-allergenic spiral tapes from Atex Medical, CE certification as a medical product by Medical Device Directive 93/42/EEC seit 2007/47/EC, Standards ISO 10993-1, ISO 14971) starting after a first evaluation and documentation of the scar 4–6 weeks after surgery for 2 cycles of 2–3 weeks. These skin-colored tapes do not penetrate the epidermis, do not contain transdermal medication and function mechanically. Application of the tape is simple and approved for doctors as well as for physical therapists.
Dermis fat graft harvesting
Surgery was performed under general anaesthesia employing the technique described by Smith et al. . In brief, the DFG with a standard size of 25mm in diameter and thickness in adults was harvested from the gluteal region of the patients incising the epidermis superficially with a No. 15 scalpel, injection of saline intradermally at the donor site, then dissecting and separating the epidermis from the dermis layer by a No. 20 blade. Then, after deep transection of the fat layer, the dermis fat graft was explanted and the wound closed in two layers with three 2.0 absorbable subcutaneous sutures (Vicryl®, Ethicon, Johnson & Johnson Medical GmbH, Norderstedt, Germany in both groups) after control of obvious bleeding using bipolar cautery. Closure of the skin was performed with 2.0 silk mattress sutures. Excision of “dog’s ears” for better wound adaptation, if performed, was annotated for analysis.
At the donor site, steristrips were placed perpendicularly over the sutured wound followed by a sterile dressing for 2 days. Wound adaptation was then checked. Gluteal sutures were removed at 10–12 days after surgery.
Application of kinesiotapes
In the case group, the kinesiotapes were fitted over the clean scar without tension after having checked and documented proper wound healing thus far. They were then left in place for 2–3 weeks until they could be peeled off easily. Another cycle of kinesiotaping was applied if the scar was free of irritation (all cases). No further topical treatment was applied to the scar.
Postoperative evaluation and assessment of the gluteal scar
Postoperative follow-up visits were performed 4–6 weeks after surgery prior to first prescription of the prosthesis (V1), as well as another 3 months later (V2). At both points in time, overall patient content was elaborated (binary response noted, yes or no, respectively).
Wound healing was evaluated within the orbit and at the gluteal donor site of the DFG. Gluteal wound healing was documented by a still photographed close-up of the donor site at approximately 30cm distance using a digital camera with a metric scale (calibration in cm and mm) placed carefully next to the scar without covering any parts. The pictured gluteal section measured approximately 10x10cm and excluded the perianal region. Cosmetic evaluation of the scar was performed by two blinded observers separately using the same lighting and computer screen. The visibility of the scar was graded from grade 0 (scar not visible), 1 (minimally visible), 2 (moderately visble) and 3 (maximally visible) at both examinations. Additionally, total length at V1 and V2 as well as final color (erythema or normal skin color), prominence and indentation (presence or absence, respectively) of the scar were assessed.
Potential wound-healing confounders included patient gender (female or male), patient age at surgery, surgical resection of so-called “dog’s ears” for better wound adaptation, patient body-mass-index (BMI), the surgeon (1, 2, and 3) and anticoagulation.
Demographic data (age group, sex, laterality as well as comparison of scar grading) were analysed by Fisher’s exact test. The changes of the scar from baseline (4–6 weeks after surgery) to next follow-up (3 months later) were analysed by Wilcoxon signed rank test. Inter-observer reliability was compared by Kappa test. For all tests, P < 0.05 was considered to be statistically significant.