Augmented Reality to Assist Skin Paddle Harvesting in Osteomyocutaneous Fibular Flap Reconstructive Surgery: A Pilot Evaluation on a 3D-Printed Leg Phantom

BackgroundAugmented Reality (AR) represents an evolution of navigation-assisted surgery, providing surgeons with a virtual aid contextually merged with the real surgical field. We recently reported a case series of AR-assisted fibular flap harvesting for mandibular reconstruction. However, the registration accuracy between the real and the virtual content needs to be systematically evaluated before widely promoting this tool in clinical practice. In this paper, after description of the AR based protocol implemented for both tablet and HoloLens 2 smart glasses, we evaluated in a first test session the achievable registration accuracy with the two display solutions, and in a second test session the success rate in executing the AR-guided skin paddle incision task on a 3D printed leg phantom.MethodsFrom a real computed tomography dataset, 3D virtual models of a human leg, including fibula, arteries and skin with planned paddle profile for harvesting, were obtained. All virtual models were imported into Unity software to develop a marker-less AR application suitable to be used both via tablet and via HoloLens 2 headset. The registration accuracy for both solutions was verified on a 3D printed leg phantom obtained from the virtual models, by repeatedly applying the tracking function and computing pose deviations between the AR-projected virtual skin paddle profile and the real one transferred to the phantom via a CAD/CAM cutting guide. The success rate in completing the AR-guided task of skin paddle harvesting was evaluated using CAD/CAM templates positioned on the phantom model surface.ResultsOn average, the marker-less AR protocol showed comparable registration errors (ranging within 1-5 mm) for tablet-based and HoloLens-based solution. Registration accuracy seems to be quite sensitive to ambient light conditions. We found a good success rate in completing the AR-guided task within an error margin of 4 mm (97% and 100% for tablet and HoloLens, respectively). All subjects reported greater usability and ergonomics for HoloLens 2 solution.ConclusionsResults revealed that the proposed marker-less AR based protocol may guarantee a registration error within 1-5 mm for assisting skin paddle harvesting in the clinical setting. Optimal lightening conditions and further improvement of marker-less tracking technologies have the potential to increase the efficiency and precision of this AR-assisted reconstructive surgery.

Avoiding second donor site and the second set of neck vessels in a case of absent peroneal skin perforators

This report describes the procedure of a case in which the skin paddle of the free fibula flap derived its supply solely from a soleal musculocutaneous perforator originating from the posterior tibial system. In contrast, the osteo-muscular component was supplied by the peroneal vascular system. We harvested the skin paddle with its vascular supply from the posterior tibial artery separately, and the osteo-muscular fibula was harvested with its supply from peroneal vessels. In this way, we avoided violation of the second donor site for the skin paddle. In addition, we used the distal end of peroneal vessels to salvage our skin paddle instead of sacrificing another set of neck vessels for anastomosis. This technique may also be utilised in cases where the neck vessels may not be available due to previous surgeries, radiation therapy, or decision by the surgery team to not sacrifice two sets of neck vessels for anastomosis.

Chimerization of Monitor Flap in a Vascularized Ulnar Nerve Flap Is an Efficient Way for Vascularity Monitoring and the Reinnervation Checkup after Its Transplantation

Background Free vascularized ulnar nerve flaps (VUNF) are effective method for long nerve defects reconstruction. However, the monitorization of its microvascular circulation and the nerve regrowth can be challenging since it is usually designed as a buried flap. We designed a skin paddle based on a septocutaneous perforator from the ulnar artery that can be dissected and raised in conjunction with the vascularized ulnar nerve flap, which aims to improve postoperative monitorization to optimizing the clinical results. Methods We retrospectively reviewed 10 cases with long nerve defects who underwent reconstruction using VUNF between June 2018 and June 2019, including eight acute brachial plexus injuries, 1 multiple nerve injury due to a rolling machine accident, and 1 sequalae of nerve injury after arm replantation. All the demographic data, surgical details, outcomes, and perioperative complications were recorded. Results We evaluated 10 male patients, with a mean age of 34 ± 16 years. Cases included 5 antegrade, 4 retrograde, and 1 U-shaped VUNF. All chimeric skin paddles survived, and all of the underlying nerves presented with adequate circulation and functional improvement. There were no intraoperative or microvascular complications. One skin paddle had a transitory postoperative circulation compromise due to external compression (bandage) which resolved spontaneously after pressure release. Conclusion VUNF chimerization of a septocutaneous perforator skin flap is a relatively easy and efficient method for postoperative monitorization of the nerve’s microvascular circulation as well as beneficial for postoperative Tinel’s sign checkup to confirm the success of the nerve coaptation. The outcome is potentially improved.

Submental Island Flap After Prior Contralateral Neck Dissection: A Case Series and Technical Considerations

Objectives: The submental island flap is a dependable workhorse in head and neck reconstruction. However, the viability of this flap has not been established for oral cavity reconstruction when a contralateral neck dissection has already been performed in an earlier surgical setting. The aim of this study is to highlight technical considerations and outcomes of this approach with a small case series. Methods: Three cases of oral cavity reconstruction with a submental island flap elevated in the context of a prior contralateral neck dissection are presented. Results: In all cases, a doppler was used to identify the maintenance of the submental perforator in the neck opposite the previous neck dissection. In 2 cases, level IA was included within the dissection field of the previous neck dissection. Additionally, the old neck scar was included within the skin paddle of the submental island flap in 2 cases. In all cases, excellent healing of the flap was observed without partial or complete loss. Conclusions: The submental island flap appears to be a reliable reconstruction when a previous contralateral neck dissection has been performed, even when level IA was included in the prior dissection.

Radial forearm free flap in a patient with an unusual radial artery variation: a case report

Head and neck reconstruction poses unique challenges in rehabilitating surgical defects in terms of integrity, function, and form. The radial forearm free flap (RFFF) has been widely used for defect coverage, especially in the head and neck area, but its versatility allows it to be used for soft-tissue reconstruction in various parts of the body. The vascular features of the flap are quite constant and reliable. Nevertheless, abnormalities of the forearm vascular tree have been described over the decades. We report a case of intraoral reconstruction after verrucous carcinoma recurrence in a 74-year-old woman with an unusual forearm flap, which we called the median forearm free flap, based on a median branch of the radial artery that was preoperatively detected using handheld Doppler ultrasonography. The distally located skin paddle was predominantly supplied by the aberrant median vessel with its perforators. The flap was thus safely harvested with this atypical pedicle. Successful reconstruction of the intraoral defect was achieved, with an uneventful postoperative course.

Personalized Reconstruction of Genital Defects in Complicated Wounds with Vertical Rectus Abdominis Myocutaneous Flaps including Urethral Neo-Orifice

Non-healing extensive wounds in the perineal region can lead to severe soft tissue infections and disastrous complications, which are not manageable with conservative measures. Specifically in recurrent or advanced pelvic malignancies, irradiation often leads to extensive scarring and wound breakdown, resulting in significant soft tissue defects during surgical tumor excision. Among several surgical options to reconstruct the perineum, the transpelvic vertical rectus abdominis myocutaneous (VRAM) flap has proven to be one of the most reliable methods. Specific modifications of this flap allow an individualized procedure depending on the patient’s needs. We modified this technique to include the urethral orifice into the skin paddle of VRAM flaps in three patients as a novel option to circumvent urinary diversion and maintain an acceptable quality of life.

The Utility of Indocyanine Green Dye Fluorescence Lymphography and Angiography During Wide Excision of Cutaneous Melanoma

Background and Objectives. Lymph node status is the most important prognostic factor in cutaneous melanoma patients. Recent studies showed that indocyanine green (ICG) fluorescence lymphography helps locating sentinel nodes better. Sometimes, flap reconstruction is needed after wide excision of tumor. Indocyanine green fluorescence also simplifies the intraoperative design of flaps. This study investigates the use of ICG fluorescence in patients with cutaneous melanoma during operation. Methods. We performed a single-center, retrospective study of subjects with cutaneous melanoma using ICG lymphograhy and/or angiography during wide excision of tumor between 2015 and 2019. Patients received a dermal injection of ICG and patent blue (PB) dye. The positive node was excised. Indocyanine green angiography was utilized to visualize better skin paddle during flap reconstruction if needed. Results. A total of 37 sentinel lymph nodes (SLNs) were removed in 12 patients. Indocyanine green successful localization was found in 10 of the 12 patients (83%). Three patients were found with 6 metastatic nodes on final pathology. 100% of these 6 nodes were identified by ICG, while 83% (5/6) were positive PB. Three of the 12 patients received flap reconstruction after operation, and no major complications occurred. Conclusions. ICG dye lymphangiography is a good alternative for locating SLNs in patients with melanoma. It could also visualize well perfusion skin paddle during reconstruction. We reported a reproducible and simple method to utilize ICG fluorescence in cutaneous melanoma patients.

Intramuscular Near-Infrared Spectroscopy for Muscle Flap Monitoring in a Porcine Model

Background Current near-infrared spectroscopy (NIRS)-based systems for continuous flap monitoring are limited to flaps which carry a cutaneous paddle. As such, this useful and reliable technology has not previously been applicable to muscle-only free flaps where other modalities with substantial limitations continue to be utilized. Methods We present the first NIRS probe which allows continuous monitoring of local tissue oxygen saturation (StO2) directly within the substance of muscle tissue. This probe is flexible, subcentimeter in scale, waterproof, biocompatible, and is fitted with resorbable barbs which facilitate temporary autostabilization followed by easy atraumatic removal. This novel device was compared with a ViOptix T.Ox monitor in a porcine rectus abdominus myocutaneous flap model of arterial and venous occlusions. During these experiments, the T.Ox device was affixed to the skin paddle, while the novel probe was within the muscle component of the same flap. Results The intramuscular NIRS device and skin-mounted ViOptix T.Ox devices produced very similar StO2 tracings throughout the vascular clamping events, with obvious and parallel changes occurring upon vascular clamping and release. The normalized cross-correlation at zero lag describing correspondence between the novel intramuscular NIRS and T.Ox devices was >0.99. Conclusion This novel intramuscular NIRS probe offers continuous monitoring of oxygen saturation within muscle flaps. This experiment demonstrates the potential suitability of this intramuscular NIRS probe for the task of muscle-only free flap monitoring, where NIRS has not previously been applicable. Testing in the clinical environment is necessary to assess durability and reliability.