Since the first description of the use of BTM in humans by Greenwood and Wagstaff in 2012, treatment with BTM has been reported for various indications: Burns, open soft tissue infections, traumatic and dermatological lesions, chronic wounds and ulcers [21, 31, 32]. The majority of cases are published for burns, but BTM is becoming increasingly important in reconstructive surgery in adults [26, 33]. In children, the indications for BTM in reconstructive soft tissue surgery need to be reviewed, as only three cases have been published to date [25, 27, 28].

In the present study, BTM application proved to be a reliable and versatile reconstructive procedure for pediatric patients with extremity avulsion injuries. Overall, all patients were successfully treated with BTM and grafted with autologous STSG 40 to 77 days after the injury and 30 to 39 days after BTM application. The proposed donor site was the hairy scalp as the “hidden donor site” [34]. Other donor sites were chosen mainly by older children for different reasons, e.g. patient number 1 (at previous donor site after grafting at the primary hospital). In all cases, the treatment was successful with functionally and aesthetically sufficient closure after an appropriate treatment time. These results go hand in hand with the published literature describing BTM as a fully synthetic option for the treatment of deep tissue defects in adults and burns [29]. All patients in the study underwent the two-stage surgical procedure described in detail for adults [26, 31, 32, 35].

Secondary wound healing after BTM treatment without the need of STSG was reported by Li et al. and Granick et al. [18, 31]. For relevant defect sizes, the value of secondary wound healing regarding healing time and scar quality should be carefully scrutinized. In all previously published reconstructive pediatric cases, a STSG similar to our protocol was performed [25, 27, 28]. Similar to these reports, STSG should be performed after BTM to achieve sufficient and high quality final wound closure.

Compared to other dermal substitutes, such as Integra® or cadaveric allografts, BTM has been shown to have a low complication profile in wound models in mice and pigs or in adult burns: significantly lower infection rates, lower rates of STSG shrinkage, contracture formation and high long term scar quality [17, 21, 29, 35, 36]. Clinically relevant tissue infections described after BTM application could not be reproduced in the present study [33]. Even in cases of BTM infection good results without distinct loss of relevant BTM areas are reported regularly [33]. This may be a relevant difference to Integra®, where contrary to this a loss of huge areas of Integra® is seen clinically often in occurrence of infections [25]. In mice model both templates were inaugurated similarly, but in BTM a higher neovascularization and inflammatory response was demonstrated, which may prevent infections [17].

More than half of the study patients in our cohort had a sterile wound swab taken prior to BTM application. A total of three different pathogen strains were detected, however, no infection occurred in these patients. Antibiotic treatment is not necessary from a clinical point of view, but due to our limited experience during the study period, we decided to administer antibiotic therapy in the event of pathogen detection. Noteworthy we did not observe any clinically relevant infections. Whereas in one case, we observed postoperative shrinkage (Fig. 4). This occurred in a smaller affected area without extending over a joint, resulting clinically in an even smaller scar without any functional limitation. In all larger defects with joint involvement, we observed no shrinkage and no impairment of movement with good elasticity. Unfortunately, no cutometry was performed due to absence of the device. Shrinkage is the most common complication of large wound closure after infection [7]. It leads to unfavorable aesthetic results and can lead to functional impairment, especially across joint. Reid et al. published in 2007 that wounds treated with STSG in a porcine model shrank more than those treated with artificial skin substitutes [37]. In an analysis between Integra® and BTM in a mouse model, Chesire et al. described similar wound closure using BTM or Integra® without signs of wound contracture [17].

BTM has been shown to be a reliable and simple reconstructive option to avoid complex reconstructive surgery, especially in younger growing infants with large defects and/or open tendon/bone injuries [18, 30, 38]. The major benefit of BTM compared to complex flap surgery is the simple technical feasibility due to the greater challenges in surgical flap technique at a young age, as the vessel diameter is a limiting factor in children [39]. The average age in our study group was 6.5 years, so we therefore suggest that BTM is also suitable for toddlers and infants. Similarly, in another context, we were able to successfully perform a BTM application in a preterm at the age of 28 weeks of gestation with a body weight of 700 g. Age therefore does not appear to be a limit for the use of BTM.

It is still an important question how long and whether NPWT is necessary. In everyday clinical practice, NPWT often appears to be used as a safety system for patients, relatives and physicians. On the other hand, several studies confirmed that the combination of Integra® and NPWT, artificial dermal skin substitute and NPWT or BTM and NPWT led to improve rates of its integration and skin graft take [40,41,42]. Other described advantages of BTM included early mobilization through physiotherapy and regaining partial sensation over the majority of the wound [43]. In the present study, the sensation of the reconstructed area was clinically quantified and satisfactory. For this specific question further diagnostic studies in children are required.

In our cohort, the overall treatment duration averaged 51.9 days, although the individual duration appeared to decrease during the study period. This is certainly related to the type and size of the injury, as well as the localization and the exposed structures, but also reflects to some extent our learning curve and ongoing experience with BTM. Others reported a shorter overall-treatment-time in adults with a minimum of 27 days [28, 30]. It is possible that the total treatment time may be reduced somewhat in the future, but due to the time the BTM requires to convert adequately, the total time will certainly not be less than 30–40 days including STSG.