Introduction

Nowadays, many work activities involving multiple risks are carried out, which leads to an increase in the number of accidents such as lower limb injuries with exposed bone, among others. These accidents frequently cause traumatic injuries that can worsen in some cases since there are no soft tissues—such as muscles—that protect the pretibial surface, as in the posterior compartments of the leg. Therefore, the recovery or regeneration of tissues in this area may be slow, which demands and prolongs healing time, involving the potential risk of infection due to the exposed bone surface ^1,2.

In order to recover the function of the affected area, there are different surgical techniques to cover the exposed lower limb bone that end up in long recovery processes with variable grade of functional limitation, which even lead to temporary or permanent disability of the affected extremity.

There is a therapeutic possibility of lower risk of infection since it is a closed vacuum system: the VAC® technique achieves motor recovery without muscle structure displacements that may cause temporary or permanent functional limitation because it provides coverage in the event of soft tissue loss with pretibial exposed bone ^3-5. The negative pressure wound therapy (NPWT) is a mechanical treatment used as an adjuvant in wound healing. It can be administered in a continuous or intermittent basis, for both acute and chronic lesions, and is an alternative to the traditional healing methods since it is quick, effective and easy to use ^6-8.

The VAC® technique prepares the wound bed for closure, reduces edema, promotes granulation tissue formation, reduces the bacterial load, keeps hydration (by removing exudate and reducing the bruise surface area), improves healing rates and reduces the hospital stay. The technique is carried out by placing a dressing—which can be of gaze or polyurethane foam—in the injury, sealing it with a semiocclusive dressing and applying subatmospheric pressure through a drainage tube connected to a computerized pump, which is useful to promote wound healing ^9-12.

Several international studies on the VAC® technique conducted in the last twenty years satisfactorily agree with the results obtained with NPWT, a technique that is more frequently used in private hospitals ¹⁶. Clinical cases with complicated lesions were successfully treated with this method in complex areas of exposed tissue—particularly the lower extremities—with good functional results, which allowed patients to return to their daily activities in less time and without secondary complications compared to other treatments that cause functionality problems ^13-15.

De Juan Pérez, in his study conducted in 2010, used the VAC® therapy in lower limb complex trauma, resulting in the reduction of infection and acceleration of lesion granulation, which helped to improve the prognosis of risk of lower limb amputation and be of benefit to serious open fractures ¹.

Materials and methods

Results

The results confirmed the objective of the study. The functional grade was evaluated with the VAC® system technique and the medial calf muscle flap coverage technique.

The research was conducted in patients with traumatic lower limb injuries, where vacuum therapy was confirmed as a useful and safe option. The VAC® method is a mechanical closure system that applies sustained negative force to the whole wound, thus avoiding its retraction and promoting the constant reduction of its diameter. This eliminates interstitial fluid, which may contribute to reduce edema. As a result, there is an enhanced blood flow to the wound (Figure 1).

Figure 1 Lower right limb with exposed bone before starting the VAC® technique and (solved) areas with exposed bone covered by granulation tissue after using the vacuum therapy 

Source: researcher’s photographs.

The main immediate complications from the two techniques were determined, finding more complications in the patients treated with the flap technique compared to those treated with the VAC® technique (37.5 % and 10 %, respectively); such differences were statistically significant (p < 0.05) (Table 1).

The time to wound closure was longer with the VAC® technique compared to the flap technique, showing significant differences (p < 0.05) (Table 2 and Figure 2).

Figure 2 Comparison of time to closure by technique type 

Moderate to severe pain was reported: pain was higher in patients who underwent the flap technique compared to those who underwent the VAC® technique (0 % and 100 %, respectively), being the differences statistically significant (p < 0.05) (Table 3).

The attending physician should periodically examine the wounds treated with the VAC® NPWT. The dressings were changed every 48 to 72 hours: dressing change intervals were established by continuous wound evaluation (Table 4).

The average number of changes with the VAC® technique is 4.70 with a variability of 1.06 changes.

The results of the FAC scale revealed that the patients were satisfied with the VAC® technique, with prevalence of functional grade V (50 %), compared to the medial calf muscle flap coverage technique, which showed a prevalence of functional grade IV (50 %). Statistically significant differences were found in the overall results (p < 0.05) (Figure 3).

Figure 3 Percent distribution of FAC scale functional measurement by technique 

Discussion

Regarding the functional grade, the research showed a positive relationship between the coverage of lower limb injuries with exposed bone and the VAC® system technique, which was effective compared with the medial calf muscle flap technique in patients treated at Clínica Stella Maris during 2019 ^17-19. The results showed the significance of the functional measurement, with higher FAC scale scores, in patients who underwent the VAC® technique.

Our study agrees with the one conducted by BernalMartínez et al. ¹⁷ (Mexico), who treated with surgical debridement cases of full-thickness burns with exposed bone that caused coverage defects because of the limited availability of tissues to reconstruct these defects. The results stood out the complete wound closure after the total bone coverage with granulation tissue and subsequent skin graft. Therefore, it is concluded that the vacuum therapy is a useful and safe option that stimulates wound closure and minimizes the need for surgical treatment for full-thickness burns with exposed bone ^17-19.

Additionally, De Juan Pérez ¹ (Spain) conducted an analytic observational study in order to use the VAC® therapy in case of a serious left leg trauma. The results of NPWT with this system demonstrated that it reduced the risk of infection of serious fractures, which notably accelerated wound granulation. After admission to the hospital, a good granulation tissue over a large part of the surface could be observed since the first VAC® dressing change. This fact significantly improved the appearance and prognosis of risk of leg amputation. If compared with the results of this research, the VAC® system poses a milestone for acute or chronic complex injury treatment since it is an important therapeutic tool to treat serious open fractures of lower limbs. The relationship between the time to closure or coverage and the results shows that the VAC® system technique is effective ^20-22.

In 2018, Maitret-Velázquez et al. ²⁹ (Mexico) claimed that NPWT accelerated wound healing, which facilitated intrahospital treatment: pain and function of lower limb injuries were controlled and infections were prevented, which helped wound closure in medically compromised patients. This agrees with the present study on the evaluation of the functional grade using the VAC® system technique. Their study analyzed 93 patients who underwent NPWT. Surgical wound infection and vascular exposure were observed in 40.9 % and 22.6 % of the patients, respectively. NPWT or VAC® system accelerated wound healing, thereby facilitating the intrahospital treatment and controlling pain and infection; such results also agree with the present study and the difference was statistically significant.

In 2020, Goyo et al. ¹⁴ (Venezuela) observed the complete clinical improvement of all the characteristics of the wound. Moreover, their analysis also showed acceleration of the healing process, infection control and reduction of hospital stay. This demonstrated that no complications were found with the use of the VAC® system, which agrees with our results.

According to different research studies reviewed and the results of this study, it was possible to analyze and determine that NPWT is a non-invasive treatment that nowadays is included in general surgery. It is used to treat chronic, acute and complex wounds, in order to reduce the number of wound healing procedures and the time required to perform them, as well as avoid surgeries involving an elevated morbidity for the patient. The VAC® system allows reducing the number of weekly wound healing procedures and the time required to perform them, so patients recover their functionality and are able to walk independently during their rehabilitation ^23-25.

In conclusion, according to the FAC scale, patients who underwent the VAC® technique showed a better recovery than those who underwent the medial calf muscle flap coverage technique since 50 % of the VAC® group got grade V functionality and 50 % of the flap group got grade IV functionality. The differences were statistically significant in the overall results ^26-27. Also, the main immediate complications from the two techniques—i.e., bleeding and infection—were determined, finding more complications in the patients treated with the flap technique compared to those treated with the VAC® technique (37.5 % and 10 %, respectively); such differences were statistically significant ^28-29.

On the other hand, the difference in the postoperative pain intensity between the two techniques was evident, being moderate to severe in patients who underwent the flap technique and mostly mild among those who underwent the VAC® technique. The difference was statistically significant (p < 0.05).

Regarding the vacuum therapy, this is a useful and safe option that stimulates wound closure and minimizes the need for wide surgical treatment in wounds with exposed bone. This has a positive impact on patients’ financial situation because it avoids expensive treatments. Moreover, it helps workers to resume their daily and social activities.

The VAC® technique or NPWT is an alternative that should be preferred over the flap technique since the principles of reconstructive surgery include protecting limb motor function, which is one of the most important objectives.