Mandibular reconstruction in elderly patients

Updates on temporomandibular joint reconstruction following ablative surgery

PURPOSE OF REVIEW

Considerations regarding reconstruction of the temporomandibular junction (TMJ) following ablation have been underreported in head and neck surgery literature. Here, we discuss the complexity of reconstructing this unique joint and highlight the benefits and drawbacks of free tissue transfer. Additionally, we address the growing role of customized alloplastic implants and virtual surgical planning technologies in TMJ reconstruction.

RECENT FINDINGS

Technological advances in computerized manufacturing, 3D printing, and virtual reality have led to a recent burgeoning in patient-specific customization that may become the method of choice in these complex reconstruction cases.

SUMMARY

Since trauma and malignancy rarely compromise the entire TMJ, guidelines currently do not exist regarding how to best reconstruct the region in these unique cases. The methods that work in ankylosis and other intrinsic joint diseases are likely less appropriate in this patient population. Recent literature has reported improved patient outcomes and reduced operative times with virtual surgical planning techniques that may optimize autogenous graft approaches.

Early and Late Complications of Mandibulectomy Free Flap Reconstruction: Does the Selective Use of Soft Tissue Only Flaps Reduce Complications?

PURPOSE

This study aims to evaluate the factors most associated with early and late complications following microvascular free tissue transfer (MVFTT) after mandibulectomy.

METHODS

A retrospective review of patients undergoing MVFTT after segmental mandibulectomy from September 2016 to February 2021 was performed across a single academic institution. Surgical variables were collected, including the location of the resultant mandibular defect (anterior vs posterior) and flap type (osseous or non-osseous). The primary outcome variables included postoperative complications (early, <90 days; and late, >90 days) and the patients' functional status (return to oral intake). Descriptive statistics, chi-square test, Fischer's exact test, and 2-sample t tests were used to analyze differences among variables.

RESULTS

We analyzed a cohort of 114 consecutive patients with mandibular defects, comprising 57 anterior and 57 posterior defects. Bony free flaps with hardware were used to reconstruct 98% of anterior defects compared to 58% of posterior defects (P < .001). All soft tissue only flaps did not utilize any hardware during the reconstruction. Anterior defects demonstrated more late complications requiring additional surgery (30% vs 9%, P = .04). A secondary analysis of posterior mandibular reconstructions compared soft tissue only flaps and bony free flaps with hardware and showed equivalent rates of early (12% vs 13%, P > .99) and late (9% vs 8%, P > .99) complications requiring additional surgery while demonstrating a similar return to full oral competence (55% vs 46%, P = .52) and recovery of a 100% oral diet (67% vs 54%, P = .53).

CONCLUSION

Osseous free tissue transfer for segmental mandibular defects remains the gold standard in reconstruction. In our patient cohort, anterior mandibular defects are associated with greater late (>90 day) complications requiring additional surgery. Comparable outcomes may be achieved with soft tissue only versus osseous free flap reconstruction of posterior mandibular defects.

Evaluation of aesthetic outcomes of mandibular reconstruction using artificial intelligence

BACKGROUND

Although vascularized bone graft (VBG) transfer is the current standard for mandibular reconstruction, reconstruction with a mandibular reconstruction plate (MRP) and with a soft-tissue flap (STF) alone remain crucial options for patients with poor general conditions. However, objective aesthetic outcome evaluations for these methods are limited.

METHODS

In a retrospective analysis of 65 patients (VBG, 33; MRP, 19; and STF, 13), mandibular asymmetry value was calculated for each patient's photograph using facial recognition AI, with a higher value indicating worse asymmetry.

RESULTS

The MRP group had a value comparable to the VBG group regardless of mandibular defect types. The STF group had a significantly higher value than the VBG group.

CONCLUSIONS

Regarding cosmesis, STF was inferior to VBG, whereas MRP was comparable to VBG, even for anterior defects for which rigid reconstruction is mandatory. However, MRP's risks of plate-related complications limit its use to cases where VBG is contraindicated or with poor prognosis.

LEVEL OF EVIDENCE: 4

Mandibular shape prediction model using machine learning techniques

OBJECTIVE

To create a mandibular shape prediction model using machine learning techniques and geometric morphometrics.

MATERIALS AND METHODS

Six hundred twenty-nine radiographs were used to select the most appropriate craniomaxillary variables in different craniofacial pattern classifications using a support vector machine. To obtain the three-dimensional mandibular shape, a Procrustes fit was used on 55 tomograms, in which 17 three-dimensional landmarks were digitized. A partial least square regression was employed to find the best covariation between craniomaxillary angles and the symmetric components of mandibular shape. The model was applied to a new sample of six tomograms and evaluated by the mean absolute error. Each mandible predicted was assessed using the Hausdorff distance (HDu) and a color scale. The model was also exploratively applied to six new radiographs.

RESULTS

Covariation was 88.66% with a significance of < 0.0001 explained by twelve craniomaxillary variables. Low differences between the original and predicted models were obtained, with a mean absolute error of 0.0143. The mean distance between meshes ranged from 0.0033 to 0.0059 HDu and each color scale demonstrated general similarity between the surfaces.

CONCLUSIONS

This approach offered promising results in obtaining a mandibular prediction model that enhances shape properties in an economical way and is applicable to a Latin American population. Clinical proof of this method will require further studies with larger samples.

CLINICAL RELEVANCE

This method offers a reliable, economic alternative to traditional mandibular prediction methods and is applicable to the Latin American population.

Complication of osteo reconstruction by utilizing free vascularized fibular bone graft

The success of free vascularized fibular bone graft (FVFBG) has accelerated the osteo reconstruction which results from trauma, resection of a tumor or an infectious bone segment, or correction of congenital deformity. But the complication behind should not be overlooked. The failure could necessitate a second surgery, which prolong the rehabilitation period and produce further health cost. Worst, the patients may suffer a permanent impaired ankle function, or a sustained morpho-functional loss on reconstructive area which are hard to save. To provide an overview of the complication related to reconstruction by FVFBG, a narrative review is conducted to identify the complications including their types and rates, the contributing factors, the approaches to measure and the techniques to avoid. Methodologically, by quick research on Pubmed and abstract reading of reviews, we characterize five reconstructive areas where FVFBG were most frequently applied: extremities, mandible, spine, osteonecrosis of femoral head, and penile. Following, the complications on different reconstructive areas are retrieved, studied and presented in five (or more specifically, six) separate sections. By the way, meaningful difference between FVFBG and other bone flap was presented in a few words if necessary. Donor-site morbidities were studied and summarized as a whole. In these literatures, the evidences documented on limb and mandibular reconstruction have the fullest detail, followed by the spine and lastly the penile. In conclusion, FVFBG, though a mature technique, needs further deep and comprehensive study and maybe device-based assistance to achieve better reconstructive effect and minimize donor-site damage.