[Clinical anatomy of the free latissimus dorsi myocutaneous flap and its application in the restoration of giant defects of the head and neck].

PURPOSE: To investigate the feasibility and effect of free latissimus dorsi myocutaneous flap in the reconstruction of giant head and neck defects. METHODS: Free latissimus dorsi myocutaneous flap on the cadaver was simulated dissected, and measured by Image-Pro Plus 6.0 to assess the feasibility of repairing giant head and neck defects. Between May 2011 and September 2022, seven patients with giant head and neck defects of different causes repaired with the latissimus dorsi myocutaneous flap were retrospectively analyzed. RESULTS: The diameter of the initiating thoracodorsal artery was (4.03±0.56) mm, and the mean lengths of the arteriolar and venous pedicles of the latissimus dorsi myocutaneous flaps obtained from human specimens were (85.5±10.5) mm and (104±4.2) mm, respectively. Among 7 patients, 5 cases had scalp defects, the remaining 2 cases had neck defects. There were no substantial postoperative problems in the donor site, and all seven latissimus dorsi myocutaneous flaps were successfully transplanted. CONCLUSIONS: For the treatment of considerable head and neck deformities, the latissimus dorsi myocutaneous flap is an optimal muscle flap due to its abundance of tissue, enough length of vascular pedicles, and sufficient venous drainage.

Comparative analysis of GoPro and digital cameras in head and neck flap harvesting surgery video documentation: an innovative and efficient method for surgical education.

BACKGROUND: An urgent need exists for innovative surgical video recording techniques in head and neck reconstructive surgeries, particularly in low- and middle-income countries where a surge in surgical procedures necessitates more skilled surgeons. This demand, significantly intensified by the COVID-19 pandemic, highlights the critical role of surgical videos in medical education. We aimed to identify a straightforward, high-quality approach to recording surgical videos at a low economic cost in the operating room, thereby contributing to enhanced patient care. METHODS: The recording was comprised of six head and neck flap harvesting surgeries using GoPro or two types of digital cameras. Data were extracted from the recorded videos and their subsequent editing process. Some of the participants were subsequently interviewed. RESULTS: Both cameras, set at 4 K resolution and 30 frames per second (fps), produced satisfactory results. The GoPro, worn on the surgeon's head, moves in sync with the surgeon, offering a unique first-person perspective of the operation without needing an additional assistant. Though cost-effective and efficient, it lacks a zoom feature essential for close-up views. In contrast, while requiring occasional repositioning, the digital camera captures finer anatomical details due to its superior image quality and zoom capabilities. CONCLUSION: Merging these two systems could significantly advance the field of surgical video recording. This innovation holds promise for enhancing technical communication and bolstering video-based medical education, potentially addressing the global shortage of specialized surgeons.

Head model dataset for mixed reality navigation in neurosurgical interventions for intracranial lesions.

Mixed reality navigation (MRN) technology is emerging as an increasingly significant and interesting topic in neurosurgery. MRN enables neurosurgeons to "see through" the head with an interactive, hybrid visualization environment that merges virtual- and physical-world elements. Offering immersive, intuitive, and reliable guidance for preoperative and intraoperative intervention of intracranial lesions, MRN showcases its potential as an economically efficient and user-friendly alternative to standard neuronavigation systems. However, the clinical research and development of MRN systems present challenges: recruiting a sufficient number of patients within a limited timeframe is difficult, and acquiring low-cost, commercially available, medically significant head phantoms is equally challenging. To accelerate the development of novel MRN systems and surmount these obstacles, the study presents a dataset designed for MRN system development and testing in neurosurgery. It includes CT and MRI data from 19 patients with intracranial lesions and derived 3D models of anatomical structures and validation references. The models are available in Wavefront object (OBJ) and Stereolithography (STL) formats, supporting the creation and assessment of neurosurgical MRN applications.

A computational modelling tool for prediction of head reshaping following endoscopic strip craniectomy and helmet therapy for the treatment of scaphocephaly.

BACKGROUND: Endoscopic strip craniectomy followed by helmet therapy (ESCH) is a minimally invasive approach for correcting sagittal craniosynostosis. The treatment involves a patient-specific helmet designed to facilitate lateral growth while constraining sagittal expansion. In this study, finite element modelling was used to predict post-treatment head reshaping, improving our comprehension of the necessary helmet therapy duration. METHOD: Six patients (aged 11 weeks to 9 months) who underwent ESCH at Connecticut Children's Hospital were enrolled in this study. Day-1 post-operative 3D scans were used to create skin, skull, and intracranial volume models. Patient-specific helmet models, incorporating areas for growth, were designed based on post-operative imaging. Brain growth was simulated through thermal expansion, and treatments were modelled according to post-operative Imaging available. Mechanical testing and finite element modelling were combined to determine patient-specific mechanical properties from bone samples collected from surgery. Validation compared simulated end-of-treatment skin surfaces with optical scans in terms of shape matching and cranial index estimation. RESULTS: Comparison between the simulated post-treatment head shape and optical scans showed that on average 97.3 ± 2.1 % of surface data points were within a distance range of -3 to 3 mm. The cranial index was also accurately predicted (r = 0.91). CONCLUSIONS: In conclusion, finite element models effectively predicted the ESCH cranial remodeling outcomes up to 8 months postoperatively. This computational tool offers valuable insights to guide and refine helmet treatment duration. This study also incorporated patient-specific material properties, enhancing the accuracy of the modeling approach.

Simulated augmented reality-based calibration of optical see-through head mound display for surgical navigation.

PURPOSE: Calibration of an optical see-through head-mounted display is critical for augmented reality-based surgical navigation. While conventional methods have advanced, calibration errors remain significant. Moreover, prior research has focused primarily on calibration accuracy and procedure, neglecting the impact on the overall surgical navigation system. Consequently, these enhancements do not necessarily translate to accurate augmented reality in the optical see-through head mount due to systemic errors, including those in calibration. METHOD: This study introduces a simulated augmented reality-based calibration to address these issues. By replicating the augmented reality that appeared in the optical see-through head mount, the method achieves calibration that compensates for augmented reality errors, thereby reducing them. The process involves two distinct calibration approaches, followed by adjusting the transformation matrix to minimize displacement in the simulated augmented reality. RESULTS: The efficacy of this method was assessed through two accuracy evaluations: registration accuracy and augmented reality accuracy. Experimental results showed an average translational error of 2.14 mm and rotational error of 1.06° across axes in both approaches. Additionally, augmented reality accuracy, measured by the overlay regions' ratio, increased to approximately 95%. These findings confirm the enhancement in both calibration and augmented reality accuracy with the proposed method. CONCLUSION: The study presents a calibration method using simulated augmented reality, which minimizes augmented reality errors. This approach, requiring minimal manual intervention, offers a more robust and precise calibration technique for augmented reality applications in surgical navigation.

Outside Europe.

This chapter illustrates that cranial surgery was not limited to Europe. There was however no contribution to improving knowledge outside Europe until medical science departed for the Arab world.

Thickness and design features of clinical cranial implants-what should automated methods strive to replicate?

PURPOSE: New deep learning and statistical shape modelling approaches aim to automate the design process for patient-specific cranial implants, as highlighted by the MICCAI AutoImplant Challenges. To ensure applicability, it is important to determine if the training data used in developing these algorithms represent the geometry of implants designed for clinical use. METHODS: Calavera Surgical Design provided a dataset of 206 post-craniectomy skull geometries and their clinically used implants. The MUG500+ dataset includes 29 post-craniectomy skull geometries and implants designed for automating design. For both implant and skull shapes, the inner and outer cortical surfaces were segmented, and the thickness between them was measured. For the implants, a 'rim' was defined that transitions from the repaired defect to the surrounding skull. For unilateral defect cases, skull implants were mirrored to the contra-lateral side and thickness differences were quantified. RESULTS: The average thickness of the clinically used implants was 6.0 ± 0.5 mm, which approximates the thickness on the contra-lateral side of the skull (relative difference of -0.3 ± 1.4 mm). The average thickness of the MUG500+ implants was 2.9 ± 1.0 mm, significantly thinner than the intact skull thickness (relative difference of 2.9 ± 1.2 mm). Rim transitions in the clinical implants (average width of 8.3 ± 3.4 mm) were used to cap and create a smooth boundary with the skull. CONCLUSIONS: For implant modelers or manufacturers, this shape analysis quantified differences of cranial implants (thickness, rim width, surface area, and volume) to help guide future automated design algorithms. After skull completion, a thicker implant can be more versatile for cases involving muscle hollowing or thin skulls, and wider rims can smooth over the defect margins to provide more stability. For clinicians, the differing measurements and implant designs can help inform the options available for their patient specific treatment.

Flap loss in head and neck reconstruction: Is there a singular cause for failure?

Despite the high success rates reported in head and neck reconstruction, free flap failures continue to persist. Understanding the factors associated with flap loss and improving overall success are paramount. This study aimed to comprehensively assess the factors influencing flap revision and free tissue transfer survival in head and neck reconstruction. The study included 70 patients with defects in the lower two-thirds of the head and neck region and underwent reconstruction using free flaps. Patient age, gender, smoking status, comorbidities and data on the location and aetiology of the defect, the specific type of flap employed, the recipient artery and vein chosen, instances of revision and the overall success of the flap were collected. The investigation aimed to establish correlations between these variables as well as flap success and revision rates. No statistically significant differences were observed in arterial and venous anastomosis revision rates, or flap survival, in relation to variables such as age, gender, flap type, smoking status, comorbidities, recipient artery or vein and the number of vein anastomoses. The malignant tumour group exhibited a lower requirement for arterial revision and a higher flap survival rate compared to the benign tumour group. This study underscores the comparable safety profiles of perforator-based and conventional flaps in head and neck reconstruction. Furthermore, it reveals that patient characteristics are not contraindications for free tissue transfer. Additionally, the quantity of the veins and choice of recipient vessels are flexible and do not significantly impact flap success. The higher rates of flap success in patients with malignant aetiology requires further investigation.

Head growth in patients with myelomeningocele treated with prenatal and postnatal surgery.

OBJECTIVE: The need for permanent CSF diversion is lower in patients who have undergone prenatal surgery for myelomeningocele (MMC) than in those who have undergone postnatal closure. Differences in brain development and head growth between treatment groups are not known, particularly for those who do not require surgical treatment for hydrocephalus. The objective of this study was to determine differences in head growth and to generate MMC-specific head circumference (HC) growth curves for patients who underwent either prenatal or postnatal surgery. METHODS: The authors retrospectively identified patients from St. Louis Children's Hospital who were treated for MMC between 2016 and 2021. HC data were obtained from birth until the most recent follow-up or hydrocephalus treatment. Nonlinear least-squares regression analysis was performed to fit the data into four models: two-term power, Gompertz, West ontogenetic, and Weibull. Subsequently, the curves were assessed for their utility in predicting hydrocephalus treatment. RESULTS: Sixty-one patients (29 females [47.5%], 25 [41%] underwent prenatal surgery, mean gestational age at birth 36.6 weeks) were included in the study. The Weibull model best fit the HC data (prenatal adjusted R2 = 0.95, postnatal adjusted R2 = 0.95), while the Gompertz model had the worst fit (prenatal adjusted R2 = 0.56, postnatal adjusted R2 = 0.39) across both cohorts. Prenatal MMC repair patients had significantly larger HC measurements than their postnatal repair counterparts. The 50th percentile of the Weibull curve was determined as a useful threshold for hydrocephalus treatment: children with HC measurements that crossed and remained above this threshold were significantly more likely to have hydrocephalus treatment regardless of time of MMC repair (prenatal relative risk [RR] 10.0 [95% CI 1.424-70.220], sensitivity 85.7% [95% CI 0.499-0.984], and specificity 82.4% [95% CI 0.600-0.948]; postnatal RR 4.750 [95% CI 1.341-16.822], sensitivity 90.5% [95% CI 0.728-0.980], and specificity 75.0% [95% CI 0.471-0.924]). The HC growth curves of the MMC patients treated prenatally were significantly larger than the WHO HC curves (p < 0.001). CONCLUSIONS: The Weibull model was identified as the HC growth curve with the best fit for MMC patients and serves as a useful predictor of hydrocephalus treatment. For MMC patients with hydrocephalus, prenatal repair patients fit the model well but postnatal repair patients did not, potentially indicating different mechanisms of hydrocephalus development. Those treated prenatally had significantly larger HC measurements compared with both the general population and those treated postnatally. Further study is needed to understand the long-term cognitive outcomes and optimal management of clinically asymptomatic patients with large HC measurements who were treated prenatally for MMC.

Evaluating Head and Neck Reconstruction Outcomes Proves Difficult-Seeking Improvement in Reporting.

This Viewpoint advocates for the improvement of the quality of head and neck reconstruction studies through accurate depictions of the defect and reconstruction performed.

[Repaired four cases of hypopharyngeal combined neck skin defects using a folded supraclavicular flap].

Objective:To evaluate the outcomes following the use of folded supraclavicular flap repaired hypopharyngeal combined neck skin defects. Methods:Folded supraclavicular flap were designed to repaired four cases of hypopharyngeal combined neck skin defects patients. Evaluate their repair effect （3 men,1 woman; mean age:66 years）. Hypopharyngeal fistula from 3.2 cm×1.8 cm to 4.5 cm×3.8 cm,skin defects in the neck from 3.8 cm×2.2 cm to 5.1 cm×4.5 cm. The folded supraclavicular flap from 8 cm×5 cm to 13 cm×9 cm. Results:All flaps survived, head and neck appearance was satisfactory, and no patient experienced a major complication. All patients resumed an oral diet function. No fistula recurrence or stricture developed after 6-19 months of follow-up. Conclusion:The folded supraclavicular flap is a safe and effective flap Repaired for hypopharyngeal combined neck skin defects.

Is hardware colonization associated with latent hardware complications and removal in maxillomandibular free flap reconstruction?

BACKGROUND: The relationship between hardware colonization, latent hardware complications, and hardware removal remains unclear following osteocutaneous free flap reconstruction of the jaws. METHODS: Retrospective cohort study of all patients undergoing free flap reconstruction of the maxilla or mandible from 2016 to 2021. RESULTS: A total of 240 subjects were included. Hardware colonization was associated with latent hardware complication in bivariate (p ≤ 0.001) and multivariate analysis (p ≤ 0.001). Time to latent hardware complication was 6.87 months earlier in colonized subjects (p ≤ 0.001). Of the 35 subjects undergoing hardware removal, 25 initiated but failed conservative therapy, and resolution of symptoms was achieved in 24 subjects after one operative intervention and 33 subjects after repeat intervention if indicated. CONCLUSIONS: Hardware colonization increases the risk and onset of latent hardware complication. Prompt hardware removal may improve outcomes by leading to faster resolution of symptoms without the burden and cost of conservative therapies.

Use of supermicrosurgery in craniofacial and head and neck soft tissue reconstruction: a systematic review of the literature and meta-analysis.

Supermicrosurgery is an evolving approach in the reconstruction of head and neck (HN) and craniofacial (CF) defects. This systematic review aims to evaluate the use of supermicrosurgery for arterial or combined arterial and venous anastomoses in the reconstruction of HN and CF soft tissue defects, and the associated success, total complication, and reoperation rates. A literature search was conducted on PubMed, Dynamed, DARE, EMBASE, Cochrane, and British Medical Journal (BMJ) electronic databases (PROSPERO ID: CRD42023476825). Nine studies fulfilled the inclusion criteria with 35 patients who underwent soft tissue reconstructive procedures using supermicrosurgery. Twenty-one flaps were performed on 20 patients (57.1%) with the remaining 15 patients (42.9%) undergoing supermicrosurgical replantation. The most common pathology requiring reconstruction was HN trauma (n = 16, 45.7%) followed by malignancy (n = 15, 42.9%). The pooled success rate for supermicrosurgery was 98% (95% CI 90 to 100, p = 1.00; I2 = 0%). The cumulative complication rate across all the studies was 46% (95% CI 13 to 80, p < 0.01; I2 = 0%), and the pooled rate of reoperation was 1% (95% CI 0 to 8, p = 0.23; I2 = 24%). The use of supermicrosurgery for HN and CF soft tissue reconstruction has an overall success rate of 98%, which is commensurate with traditional microsurgery for HN reconstruction. Complication and reoperation rates are comparable to previous literature. This study confirms the feasibility of supermicrosurgery as a safe and reliable reconstructive option for HN and CF defects.

Systematic review of the free thoracodorsal artery perforator flap for head and neck reconstruction.

BACKGROUND: The thoracodorsal artery perforator (TDAP) flap has gained interest as a option for reconstruction of head and neck defects while minimizing donor site morbidity as compared to traditional workhorse flaps. The primary aim of this systematic review is to assess the postoperative outcomes and efficacy of this flap. METHODS: Several databases were screened for relevant citations. The quality of studies and risk of bias were evaluated using the MINORS scoring system. RESULTS: Twenty articles containing 168 patients undergoing at least one TDAP flap reconstruction met the inclusion criteria. There were no incidences of total flap failure and only 10 incidences of partial flap failure (5.95 %). Flap complications and donor site morbidity was low. The average MINORS score of the studies suggested a moderately high amount of bias. CONCLUSIONS: Based on limited quality evidence, this review suggests that TDAP flap is a safe and feasible option for head and neck reconstruction with comparable success rates as other commonly used flaps, with low complication rate and donor site morbidity. Further large-scale studies are warranted.

Co-surgery in head and neck microvascular reconstruction.

PURPOSE: Co-surgery with two attending reconstructive surgeons is becoming increasingly common in breast microvascular reconstruction due to case complexity and the potential for improved outcomes and operative efficiency. The impact of co-surgery on outcomes in head and neck microvascular reconstruction has not been studied. METHODS: Our multidisciplinary head and neck reconstruction team (Otolaryngology, Plastic Surgery) at the University of Pittsburgh transitioned to a practice of co-surgery on head and neck free flaps. In this study, we compare outcomes of two surgeon head and neck reconstruction to single surgeon reconstruction in a prospectively maintained database. RESULTS: 384 patients met our inclusion criteria from 2020 to 2022. Cases were performed by a single surgeon in 77.8 % of cases (299/384) and two surgeons in 22.1 % (85/384). The mean age was 62.5 years. There was no difference between the single surgeon cohort and the co-surgery cohort in terms of flap survival, procedure time, ischemia time, hospital length of stay, recipient site complications, or rates of return to the operating room. Donor site complications were less common in the co-surgery cohort (0 % vs 4.7 %, p = 0.021). For our reconstructive team, the transition to co-surgery has increased total surgeon fee collection per free flap by 28 % and increased surgeon flap related RVU production by 35 %. CONCLUSION: Co-surgery is feasible and safe in head and neck microvascular reconstruction. Benefits may include reduced complications, increased reimbursement, and improved interdisciplinary collaboration.

[Accurate tissue flap reconstruction method based on the quadratic surface developability for head and neck soft tissue defects].

Soft tissue defects resulting from head and neck tumor resection seriously impact the physical appearance and psychological well-being of patients. The complex curvature of the human head and neck poses a formidable challenge for maxillofacial surgeons to achieve precise aesthetic and functional restoration after surgery. To this end, a normal head and neck volunteer was selected as the subject of investigation. Employing Gaussian curvature analysis, combined with mechanical constraints and principal curvature analysis methods of soft tissue clinical treatment, a precise developable/non-developable area partition map of the head and neck surface was obtained, and a non-developable surface was constructed. Subsequently, a digital design method was proposed for the repair of head and neck soft tissue defects, and an in vitro simulated surgery experiment was conducted. Clinical verification was performed on a patient with tonsil tumor, and the results demonstrated that digital technology-designed flaps improved the accuracy and aesthetic outcome of head and neck soft tissue defect repair surgery. This study validates the feasibility of digital precision repair technology for soft tissue defects after head and neck tumor resection, which effectively assists surgeons in achieving precise flap transplantation reconstruction and improves patients' postoperative satisfaction.

Anatomical classification of adductor magnus perforator flap and its application in head and neck reconstruction / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the anatomical classification of adductor magnus perforator flap and its application in head and neck reconstruction. Methods: From January 2017 to January 2020, Hunan Cancer Hospital treated 27 cases of oral tumor patients (15 cases of tongue cancer, 9 cases of gingival cancer and 3 cases of buccal cancer), including 24 males and 3 females, aged 31-56 years old. The course of disease was 1-12 months. Secondary soft tissue defects with the sizes of 5.0 cm × 3.5 cm to 11.0 cm × 8.0 cm were left after radical resection of the tumors, and were repaired with free adductor magnus perforator flaps. The flaps based on the origing locations of perforator vessels were divided into three categories: ① intramuscular perforator: vessel originated between the gracilis muscle and the adductor magnus or passed through a few adductor magnus muscles; ② adductor magnus middle layer perforator: vessel run between the deep and superficial layers of adductor magnus; ③ adductor magnus deep layer perforator: vessel run between the deep layer of adductor magnus and the semimembranous muscle. Descriptive analysis was used in this research. Results: Perforator vessels of adductor magnus were found in all cases, with a total of 62 perforator branches of adductor magnus. The anatomical classification of the perforator vessels was as follows: 12 branches for class ①, 31 branches for class ② and 19 branches for class ③. The vascular pedicles of the free adductor major perforator flaps included type ① for 3 cases, type ② for 16 cases and type ③ for 8 cases. All 27 flaps survived and the donor sites were closed directly. In 18 cases, the perforator arteries and the venae comitan were respectively anastomosed with the superior thyroid arteries and veins. In 9 cases, the pedicle arteries and the venae comitan were respectively anastomosed with the facial arteries and veins. Follow up for 12-40 months showed that the appearances of the flaps and the swallowing and language functions of patients were satisfactory, apart from linear scars were left in the donor sites with no significant affect on the functions of thigh. Local recurrence occurred in 3 cases and radical surgeries were performed again followed by repairs with pedicled pectoralis major myocutaneous flaps. Cervical lymph node metastasis occurred in 2 cases and cervical lymph node dissection was performed again. Conclusions: The adductor magnus perforator flap has soft texture, constant perforator vessel anatomy, flexible donor location and harvesting forms, and less damage to the donor site. It is an ideal choice for postoperative reconstruction in head and neck tumors.

Accurate tissue flap reconstruction method based on the quadratic surface developability for head and neck soft tissue defects / 生物医学工程学杂志

Soft tissue defects resulting from head and neck tumor resection seriously impact the physical appearance and psychological well-being of patients. The complex curvature of the human head and neck poses a formidable challenge for maxillofacial surgeons to achieve precise aesthetic and functional restoration after surgery. To this end, a normal head and neck volunteer was selected as the subject of investigation. Employing Gaussian curvature analysis, combined with mechanical constraints and principal curvature analysis methods of soft tissue clinical treatment, a precise developable/non-developable area partition map of the head and neck surface was obtained, and a non-developable surface was constructed. Subsequently, a digital design method was proposed for the repair of head and neck soft tissue defects, and an in vitro simulated surgery experiment was conducted. Clinical verification was performed on a patient with tonsil tumor, and the results demonstrated that digital technology-designed flaps improved the accuracy and aesthetic outcome of head and neck soft tissue defect repair surgery. This study validates the feasibility of digital precision repair technology for soft tissue defects after head and neck tumor resection, which effectively assists surgeons in achieving precise flap transplantation reconstruction and improves patients' postoperative satisfaction.