Reconstruction of Complex Lateral Skull Base Defects After Oral Cancer Resection With Individualized Anterolateral Thigh Flap

Augmented reality in preoperative anterolateral thigh flap perforators positioning: A pilot diagnostic study

BACKGROUND

The anterolateral thigh (ALT) flap is the primary choice for healthy and vascularized soft-tissue coverage for appendicular and axial soft tissue reconstruction, especially in the head and neck regions. Nonetheless, there is substantial anatomic variation in ALT perforators that affect flap integrity, survival rates, and donor-site morbidity. Regardless of the ALT flap type, accurate location of perforators can greatly improve surgical success rates and reduce the risk of secondary surgeries. Therefore, we investigated a novel approach for locating perforators.

METHOD

We utilized augmented reality (AR) technology in combination with a self-designed device, Finder, to locate the perforators of the anterolateral thigh (ALT) flap, and compared its accuracy to that of traditional ultrasound localization.

RESULT

In this study, 24 patients underwent ALT flap reconstruction, with all flaps surviving except one case of partial necrosis. Comparing the two positioning methods, Ultrasonic color Doppler (UCD) showed a sensitivity of 81.1 % [95 % confidence interval (CI) 64.3 %-91.4 %] and an AUC of 0.70 (95 % CI 0.55-0.86). AR-Finder demonstrated a higher sensitivity of 97.5 % (95 % CI 85.3 %-99.9 %, p = 0.031) and an AUC of 0.90 (95 % CI 0.80-1.01, p = 0.035). The average distance difference from the actual perforator to virtually determined location was 3.54 ± 2.80 mm (95 % CI 2.58-4.50) for AR-Finder and 9.57 ± 5.84 mm (95 % CI 7.75-11.58) for UCD (p < 0.001).

CONCLUSION

In this pilot study, AR-Finder demonstrated superior accuracy compared to the UCD method for locating perforators in ALT flaps, providing a new and reliable tool for the design and elevation of ALT flaps.

Random forest algorithm for predicting postoperative hypotension in oral cancer resection and free flap reconstruction surgery

This study aimed to investigate the risk factors for low postoperative blood pressure and construct a machine learning (ML) model based on these features for real-time prediction in patients with oral cancer following reconstruction surgery. The retrospective cohort analysis included adults who had undergone oral cancer resection and free flap reconstruction surgery between December 2022 and December 2023. Patient clinical characteristics were obtained from the electronic medical records. Seven ML techniques were attempted with postoperative hypotension (POH) (mean arterial pressure ˂ 55 mmHg) as the primary outcome. The best-performing ML model was tuned, and the final performance was evaluated using split-set validation, followed by risk factor identification and model interpretability. Of the 727 patients, 412 were finally included, with 66 (16.2%) experiencing POH, resulting in higher inpatient costs and prolonged hospitalization. With an area under the receiver operating characteristic curve of 0.805 (95% confidence interval [CI]: 0.674-0.935), the random forest model demonstrated excellent performance. Shapley additive explanation and feature importance analysis revealed that systolic pressure, heart rate, tumor size, lactic acid level, diastolic pressure, surgical time, total liquid infusion volume, and body mass index were significant risk factors for POH, indicating the robustness of the random forest model.

Reconstruction of Complex Oral and Maxillofacial Defects After Oral Cancer Resection With Individualized Anterolateral Thigh Multiple Paddle Flaps

PURPOSE

This study aimed to use reconstructive methods for complex oral and maxillofacial defects, explore their feasibility, and evaluate the efficacy of defect reconstruction using anterolateral thigh (ALT) multiple paddle flaps.

PATIENTS AND METHODS

The authors performed a retrospective case series of 33 patients who underwent oral and maxillofacial defect reconstruction using the ALT multiple paddle flaps. The design and harvest of the flaps, methods for defects reconstruction, and reconstructive efficacy are described.

RESULTS

All 33 patients were men, with a mean age of 49.5 years. Of the flaps, triple skin paddles plus muscle paddles were included in 3 cases, triple skin paddles were included in 1 case, 2 skin paddles plus muscle paddles were included in 29 cases. The skin paddles measured 3×5 cm to 10×16 cm. Postoperatively, all flaps survived completely. Parotid salivary fistula and orocutaneous fistula occurred in 1 patient of each, thigh wound infection and effusion occurred in 1 and 2 patients, respectively. All patients were followed up for ~2 to 93 months; most patients' oral functions and appearance were acceptable, and thigh motor dysfunction was not observed.

CONCLUSIONS

With separate skin paddles for defects of different positions, individualized muscle flap for dead spaces, combination of different skin paddles for larger defects, effective reduction or avoidance of wound complications, and acceptable donor site morbidity, the ALT multiple paddle flaps are an ideal candidate for complex oral and maxillofacial defects reconstruction.

Design and testing of an optical instrument for skin flap monitoring

Flap procedures are complex surgical tools widely used in reconstructive surgery. Flap ischemia is one of the most dangerous complications, both during the surgical procedure and during the patient's recovery, which can quickly lead to tissue necrosis (flap loss) with serious medical and psychological consequences. Today, bedside clinical assessment remains the gold standard for flap monitoring, but timely detection of flap ischemia is a difficult and challenging task, so auxiliary techniques are needed to support flap monitoring. Here we present a prototype of a new optical diagnostic tool, based on visible light absorption in diffuse reflectance spectroscopy, for non-invasive, continuous, real-time monitoring of flaps. The proposed approach is assessed by monitoring flap ischemic scenarios induced on pig animal models. The results obtained support that the proposed approach has great potential, not only for prompt detection of ischemia (in seconds), but also for clear differentiation between an arterial occlusion and venous occlusion.

The Tai Chi Flap: A Novel Design for the Radial Forearm Flap

OBJECTIVE

Tai Chi is an ancient philosophy used to explain the universe. The Tai Chi symbol is represented by Yin/Yang fishes. The authors describe a novel radial forearm flap (RFF) design for the reconstruction of circular defects based on the Tai Chi symbol.

METHODS

Eleven consecutive patients with craniofacial skin or mucus defects underwent reconstruction with a Tai Chi RFF. Patient perioperative and follow-up information was collected.

RESULTS

The diameter of the Tai Chi RFF was 5 to 6 cm. All flaps healed uneventfully without ischemic problems, and all donor site defects were closed primarily without skin grafts. Remarkably, 2 patients received a tattoo to mark the Tai Chi symbol and greatly appreciate the shape of the flap.

CONCLUSIONS

The Tai Chi flap is an economically friendly flap design that can be used to prevent skin grafts while providing psychological comfort to patients.