Is Hyperspectral Imaging Suitable for Assessing Collateral Circulation Prior Radial Forearm Free Flap Harvesting? Comparison of Hyperspectral Imaging and Conventional Allen's Test

Free Flap Reconstruction of Traumatic Skin Defects of the Entire Hand Dorsum

Background/Objectives: The reconstruction of hand defects, especially involving the dorsal region of the hand, has remained a challenge for surgeons because of its anatomical features and complex functions. The goal of reconstruction should include functional restoration as well as being esthetically pleasing. The flap transfer reconstruction strategy is essential for satisfying these requirements. Methods: Free flaps were used to cover traumatic defects of the hand dorsum in eleven patients from 2016 to 2022. Eight males and three females with a mean age of 41 years were enrolled. The size of the flaps ranged from 6 × 5 cm to 20 × 9 cm, and the selected flaps included five anterolateral thigh flaps, three lateral arm flaps, and three superficial circumflex iliac artery flaps. Results: All flaps survived, with one case of partial necrosis. One patient experienced joint stiffness during recovery. The donor sites were closed primarily, and there was no need for skin grafting. Secondary debulking or thinning was also not required. The majority of cases recovered excellent function of the hand (mean Q_DASH: 2.5) with satisfactory esthetic outcomes. The postoperative observations were followed by more than six months. Conclusions: Small defects can be treated using local, pedicled, and island-type flaps. However, larger defects involving the exposure of tendons, nerves, and other critical structures commonly require free tissue transfers. The flap reconstruction for hand dorsum in the study is feasible to produce acceptable outcomes in large sized defects.

Effects of volume management on free flap perfusion and metabolism in a large animal model study

Free flap failure represents a substantial clinical burden. The role of intraoperative volume management remains controversial, with valid studies lacking. Here, using a large animal model, we investigated the influence of volume management on free flap perfusion and metabolism. Autotransfer of a musculocutaneous gracilis flap was performed on 31 German domestic pigs, with arterial anastomosis and catheterization of the pedicle vein for sequential blood sampling. Flap reperfusion was followed by induction of a hemorrhagic shock with maintenance for 30 min and subsequent circulation stabilization with crystalloid solution, crystalloid solution and catecholamine, autotransfusion or colloidal solution. Flap perfusion and oxygenation were periodically assessed using hyperspectral imaging. Flap metabolism was assessed via periodic blood gas analyses. Hyperspectral imaging revealed no difference in either superficial or deep tissue oxygen saturation, tissue hemoglobin or tissue water content between the test groups at any time point. Blood gas analyses showed that lactate levels were significantly increased in the group that received crystalloid solution and catecholamine, after circulatory stabilization and up to 2 h after. We conclude that, in hemorrhagic shock, volume management impacts acid-base balance in free flaps. Crystalloid solutions with norepinephrine increase lactate levels, yet short-term effects on flap perfusion seem minimal, suggesting that vasopressors are not detrimental.

Dovetailing skin incision design of radial forearm free flap for forearm wound closure and maxillofacial reconstruction

Object

This study aimed to examine the feasibility of the dovetailing skin incision design of radial forearm free flap (RFFF) for closing forearm wounds and performing maxillofacial reconstruction.

Method

A total of 27 patients were divided into two groups. In the dovetail group (n = 16), forearm wounds were closed primarily and maxillofacial defects were reconstructed by dovetail RFFF. In the conventional group (n = 11), forearm wounds were closed by skin grafts from the abdomen or mattress suturing, and maxillofacial defects were reconstructed by conventional RFFF. Information on the healing time of the forearm wound, length of postsurgical hospitalization, esthetic assessments, and complications associated with the forearm wound and the maxillofacial region was collected at least 6 months postoperatively.

Result

The average size of the flap in the dovetail group was smaller than that in the conventional group (p = 0.134), and average healing time of the forearm wound in dovetail group was significantly shorter than that in conventional group (p = 0.000). Comparing with the conventional group, there were more cases in the dovetail group demonstrating decreased sensitivity (p = 1.000). Esthetic assessments of forearm wound and maxillofacial reconstructions in the dovetail group were significantly higher than that in the conventional group (p = 0.000).

Conclusion

Closure of forearm wounds and maxillofacial defects using dovetail design was found to be a feasible alternative to the conventional design.

Special Issue "Plastic and Reconstructive Surgery in Personalized Medicine"

With an ever-growing knowledge in various disciplines of medicine and with rapidly evolving new techniques and operative methods in plastic surgery, it is obvious that it becomes more and more difficult to keep up with all the developments in this field at any time [...].

Comparison of Hyperspectral Imaging and Microvascular Doppler for Perfusion Monitoring of Free Flaps in an In Vivo Rodent Model

To reduce microvascular free flap failure (MFF), monitoring is crucial for the early detection of malperfusion and allows timely salvage. Therefore, the aim of this study was to evaluate hyperspectral imaging (HSI) in comparison to micro-Doppler sonography (MDS) to monitor MFF perfusion in an in vivo rodent model. Bilateral groin flaps were raised on 20 Sprague−Dawley rats. The femoral artery was transected on the trial side and re-anastomosed. Flaps and anastomoses were assessed before, during, and after the period of ischemia every ten minutes for overall 60 min using HSI and MDS. The contralateral sides’ flaps served as controls. Tissue-oxygenation saturation (StO2), near-infrared perfusion index (NPI), hemoglobin (THI), and water distribution (TWI) were assessed by HSI, while blood flow was assessed by MDS. HSI correlates with the MDS signal in the case of sufficient and completely interrupted perfusion. HSI was able to validly and reproducibly detect tissue perfusion status using StO2 and NPI. After 40 min, flap perfusion decreased due to the general aggravation of hemodynamic circulatory situation, which resulted in a significant drop of StO2 (p < 0.005) and NPI (p < 0.005), whereas the Doppler signal remained unchanged. In accordance, HSI might be suitable to detect MFF general complications in an early stage and further decrease MFF failure rates, whereas MDS may only be used for direct complications at the anastomose site.

Long-Term Donor Site Morbidity and Flap Perfusion Following Radial versus Ulnar Forearm Free Flap—A Randomized Controlled Prospective Clinical Trial

This clinical prospective randomized controlled study aimed to investigate the differences between Radial (RFFF) and Ulnar (UFFF) Forearm Free Flap in terms of success, performance, and donor site morbidity. Thirty patients with reconstruction of the head and neck region were included. For the first time, this study assessed flap-perfusion characteristics, donor-site-wound-healing dynamics and hand perfusion using hyperspectral imaging. Further, subjective (Likert-scale, DASH-score) and objective (grip/pinch-strength) parameters of donor site morbidity were analysed. Postoperative follow-up was performed until 6 months after index surgery. With 100% of patients, RFFF and UFFF were equally successful. Compared to surrounding reference, UFFF revealed significant lower tissue oxygenation saturation (StO2) than RFFF. Compared with UFFF, blood flow in both the thenar and hypothenar region were significantly reduced 6 months following RFFF transfer. After four weeks, 27% more patients demonstrated impaired wound healing following RFFF transfer. After 6 months, epithelial-surface continuity was restored in all patients of both groups. After 6 months, overall rates of both subjective and objective donor site morbidity were comparable between RFFF and UFFF. RFFF and UFFF both demonstrate similar success rates and HSI-perfusion dynamics following transfer. After 4 weeks, wound-healing disorder appeared significantly more often in RFFF than in UFFF; however, they became equal after 6 months. RFFF and UFFF can be considered as mutual alternatives.

Thermal, Hyperspectral, and Laser Doppler Imaging: Non-Invasive Tools for Detection of The Deep Inferior Epigastric Artery Perforators-A Prospective Comparison Study

Perforator flaps have become one of the leading procedures in microsurgical tissue transfer. Individual defects require a tailored approach to guarantee the most effective treatment. A thorough understanding of the individual vascular anatomy and the location of prominent perforators is of utmost importance and usually requires invasive angiography or at least acoustic Doppler exploration. In this study, we aimed at evaluating different non-invasive imaging modalities as possible alternatives for perforator location detection. After a cooling phase, we performed thermal, hyperspectral and Laser Doppler imaging and visually evaluated a possible detection of the perforator for a period of five minutes with an image taken every minute. We identified the most prominent perforator of the deep inferior epigastric artery by handheld acoustic Doppler in 18 patients. The detected perforator locations were then correlated. Eighteen participants were assessed with six images each per imaging method. We could show a positive match for 94.44%, 38.89%, and 0% of patients and 92.59%, 25.93%, and 0% of images for the methods respectively compared to the handheld acoustic Doppler. Sex, age, abdominal girth, and BMI showed no correlation with a possible visual detection of the perforator in the images. Therefore, thermal imaging can yield valuable supporting data in the individualized procedure planning. Future larger cohort studies are required to better assess the full potential of modern handheld thermal imaging devices.