Artificial Cornea: Past, Current, and Future Directions

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Bilateral Pulmonary Arteries Reconstruction for Correction of Tetralogy of Fallot with Unilateral Absence of the Pulmonary Artery

Background: Tetralogy of Fallot (TOF) is the most common combined the deformity of unilateral absence of the pulmonary artery (UAPA). The treatment strategy of TOF combined with UAPA is still very controversial. In this study, we analyzed the effect of the bilateral pulmonary reconstruction for patients with TOF combined with UAPA. Methods: A single-institution, retrospective review of all 1713 patients with TOF between January 2009 to November 2021. Eight patients were diagnosed with TOF combined with UAPA, and 7 patients underwent the surgery. Three patients underwent one-stage TOF correction with bilateral pulmonary artery reconstruction. Three patients underwent bilateral pulmonary artery reconstruction, followed by two-stage TOF correction after several months. One patient underwent 2 procedures of left pulmonary artery reconstruction, and the VSD remained open. Results: All 7 patients survived during the postoperative follow-up and showed good cardiac function and normal oxygen saturation >97%. During the follow-up with echocardiograms, it was found that the left pulmonary arteries that were reconstructed with Goretex vessel or direct anastomosis had thrombosis or stenosis. The left pulmonary artery reconstructed with the modified autologous tissue extension technique was unobstructed. Conclusions: In patients with TOF and UAPA, if there is a pulmonary confluence in the affected hilum, it is feasible to implement bilateral pulmonary artery reconstruction for one-stage TOF correction. The use of pulmonary artery extension technique and autologous tissue to bilateral pulmonary reconstruct could reduce the incidence of anastomotic stenosis.

Combining Aesthetic Septorhinoplasty With Bioabsorbable Implants for Nasal Valve Insufficiency

This case report demonstrates the usage of a bioabsorbable nasal implant (BNI) in conjunction with an aesthetic septorhinoplasty. The authors uniquely chose to use this allograft due to inadequate autologous tissue secondary to previously performed temporomandibular joint arthroplasties. In addition to evaluating our case of a 22-year-old woman who received a BNI with an aesthetic septorhinoplasty, the authors performed a comprehensive literature review on the topic. Spanning 3 databases (Scopus, PubMed, and Cochrane), this review revealed 4 primary studies, totaling 349 patients. Each utilized nasal obstruction symptom evaluation (NOSE) scores to subjectively measure symptomatic improvement. We chose to use the NOSE questionnaire on our patient both preoperatively and postoperatively, in order to help demonstrate subjective improvement. The patient’s functional and aesthetic concerns were addressed in the operating room at Parkland Memorial Hospital under general anesthesia. Notably, the patient had previously had conchal cartilage harvested bilaterally, had insufficient septal cartilage for adequate grafting, and did not desire to undergo costal cartilage harvest. Therefore, all parties agreed to use a BNI to complete the functional component of the patient’s septorhinoplasty. This day-surgery first focused on the aesthetic septorhinoplasty followed by the placement of the BNI bilaterally. Following an uneventful postoperative course, our patient endorsed not only an aesthetic improvement but also an 88% functional improvement based on her NOSE score within 4 months of surgery. The authors were able to successfully integrate functional as well as aesthetic septorhinoplasty techniques under the constraints of having both limited autologous tissue and limited accepted options from the patient. For the patient and provider team, this newer allograft was confirmed to be effective and efficient. With the correct patient selection, this is an excellent adjunct procedure that can be quickly and safely performed either in conjunction with surgical rhinoplasty or as a standalone procedure by facial surgeons.

Techniques and materials used to optimize attached gingiva size: literature review

The aim of this review was to examine the techniques for performing keratinized gingival augmentation and grafts, as well as the materials used, which are often required to ensure proper wound closure. Tissue engineering of the oral mucosa represents an interesting alternative to obtain sufficient autologous tissue to repair oral soft tissue defects using biodegradable scaffolds and can improve vascularization and epithelialization, which are critical for successful outcomes.

Use of Tendon Allograft for Recurrent Extensor Carpi Ulnaris Instability in Ehlers–Danlos Syndrome: A Case Report

Background Subluxation of the extensor carpi ulnaris (ECU) tendon can be a challenging problem to the surgeon, with no options described for failure following autologous reconstruction. It is our intention to provide guidance on technique by describing our experience in a 20-year-old male with Ehlers–Danlos syndrome. Case Description The patient presented with pain and snapping of the ECU tendon, and failed both immobilization and ECU reconstruction with autologous extensor retinaculum. A gracilis tendon allograft was used to reconstruct the ECU sheath, in addition to ulnar groove deepening. At 1-year follow-up, the patient had no pain and the ECU was stable without recurrent subluxation. Literature Review To the authors' knowledge, the use of tendon allograft for stabilization of recurrent ECU subluxation following surgical repair or reconstruction has not been previously described in the medical literature. Clinical Relevance Utilization of tendon allograft is a viable technique to stabilize the ECU tendon while minimizing the risk in relying on compromised autologous tissue. This report represents the first account of successful reconstruction following failed autologous reconstruction.