We present the results of this retrospective observation of patients with diabetic foot ulcers (DFUs) and large skin defects residual after debridement. The main findings supported our hypothesis that application of the simple skin stretching system and negative pressure wound therapy in repair of complex diabetic foot wound was effective and safe.
Negative pressure wound therapy (NPWT) reported by Argenta and Morykwas[12] was generally used all over the world. NPWT reduces extracellular edema, improves local blood flow and stimulates local angiogenesis to increase the formation of granulation tissue[13-15]. In addition, wound bioburden and risk of infection are decreased, and wound healing is accelerated[16, 17]. Moreover, NPWT increases the expression of many cytokines to promote collagen deposition[18]. Furthermore, NPWT in patients with DFUs increases let-7f expression in plasma which may help to control the inflammation and induct the angiogenesis, both associated with wound healing[19]. However, there is a potential problem in the treatment of DFUs by using NPWT. Tissue pressure beneath the foam of NPWT system is increased by the external compression, which could decrease tissue oxygenation in wound beds, especially in diabetic foot. Jae-A. Jung et al. in their study found that NPWT would significantly reduce tissue oxygenation levels in diabetic feet, thus suggested that taking care of the compression of the foam dressing when NPWT was applied, but didn’t suggest that NPWT should be discarded in treating DFUs in considering of its various positive effects[20].
On the other hand, Liu Z et al.[4] and Matthew Wynn[21] et al. both in their review concluded that comparing with other wound dressings, it remained unclear whether NPWT could increase the proportion of diabetic foot wounds healed and reduce the time to heal the wounds of DFUs. Likewise, there is no obvious advantage in reduction of wound area by application of NPWT alone in our opinion.
In order to solve the problem, we applied a simple skin stretching system simultaneously in our clinical study. The skin stretching system is an effective method that can accelerate the wound healing by the biomechanical properties of the skin. Compared to traditional surgeries, the technique has the advantages of healing wounds without subsequent reconstruction surgeries, reducing the time for wound closure, and the properties of the stretched skin similar to the adjacent skin [22-25]. There have been various skin stretching devices for wound closure described in the literature[22, 24, 26-28]. However, the application is limited because of the availability and cost which is particularly important in a developing country with limited resources. In our cases, all materials used in the simple skin stretching system are inexpensive and easily available in most operating theatres. On account of that the skin viscoelasticity of diabetic foot is relatively poor, we take more attentions to the assessment of the mobility and quality of the neighboring cutaneous condition before applying the skin stretching system. Several studies in related fields clearly demonstrated that the skin stretching system was fairly a good adjunctive treatment for diabetic-foot wound closure, but better elucidation of the relative indications and contraindications was still needed[29-31].
There are currently few studies about application of a skin stretching system and NPWT simultaneously in diabetic foot wounds. Lee et al. proposed a similar concept in patients with necrotizing fasciitis and showed this method can be an alternative treatment for the necrotizing fasciitis patients with large wounds[32]. Zhang, F et al. in his study concluded that VSD associated with SSD in patients with stress-induced injuries could improve the therapeutic effect[33]. Wang L. C et al. [34]and Ji P et al. [29]reported that the application of skin stretching device and NPWT in diabetic foot ulceration can reduce wound healing time and increase wound healing rate. These literatures support our hypothesis that the combination of simple skin stretching system and NPWT is advantageous.
In our research, the time for closure of complex diabetic wound ranged from 8 to 19 days with a median of 14 days making it more effective than secondary intention healing and skin graft. Furthermore, the procedure is easy to operate, and less time is spent compared with flap transposition. In regards to the absolute rates of reduction, we found a fact that different anatomical sites of the foot had different viscoelastic properties. It was much easier for the side of the foot to reduce the area of diabetic foot wound than dorsum of the foot. The reason might be that the soft tissue was more on the side than on the dorsum, thus the wounds on the side could be treated with greater traction tension to promote wound healing compared with the dorsum.
It was ineluctable that some staples were occasionally dislodged due to constant tension occurred in 2 cases. In consideration of that the other staples could still maintain enough traction tension, so it had few influences for wound closure. Additionally, 3 cases of skin edge necrosis were occurred in our study. Ji Peng et al. concluded that the skin viscoelasticity and local micro-circulation of diabetic foot was relatively poor[29]. Therefore, we need to carefully assess before using the skin stretch system to avoid the complication of skin necrosis as far as possible. Moreover, pain will occur in the skin stretching system when applying a persist force. In the study, all of the patients could tolerate anchorage pain just through oral analgesics. The reason might be that the tension of elastic bandage was relatively mild and diabetic peripheral neuropathy affected sensory nerve markedly in lower extremities.