Complementing surgical with biomedical and engineering methods to evolve lip and nose reconstruction

Facial integrity and self-perception are intimately related to each other. A facial defect therefore affects a patient in his physical and psychosocial health as well. Every reconstructive method exhibit certain imperfections or burden for the patient, which motivates the surgeon’s to strive for improvements. While many imperfections can be improved by refinements of the surgical techniques, some aspects might be not solvable by surgical principles alone. At that stage, biomedical and engineering methods should be considered to complement the surgical treatment for further improvements.
We developed and explored a variety of biomedical and engineering methods to overcome shortcomings of current lip-nose reconstruction techniques.
The unknown shape of a missing nose was computed from a morphable face model that comprise the facial shape information of 200 healthy individuals. It led to a more natural shape planning than by hand carving. A biocompatible facial prosthesis was then made out of polyamide using computer assisted design and manufacturing. Alternatively to facial prosthesis large facial defects can be covered by means of tissue transfer from a distant body site performing a microsurgical vascular anastomosis. In this area, the importance to develop and use monitoring devices and pharmaceutical drugs for anastomosis patency remained unclear. We assessed therefore the current practice for microsurgical head and neck tissue transfer in clinics of Germany, Switzerland and Austria. There was a high variability with equal success rate, technical monitoring devices and pharmaceutical drugs seemed to have a negligible effect on the success rate, while the surgical anastomosis having the main effect. To repair small naso-labial defects of inborn cleft lips, the use of the adjoining tissue is sufficient. However, since both lip parts contain a labial artery of normal thickness they could be as well unified by a microsurgical anastomosis, however its biological rational needed exploration. We measured the lip artery blood flow and nose-lip microcirculation in cleft lip patients before and after surgical repair and in normal using laser Doppler flowmetry and white light tissue spectrometry. We found no circulation deficit in cleft patients and therefore no need to strive for a surgical anastomosis. Nonetheless, since blood flow is a precondition for growth and development, visible vessels in the surgical field should be preserved best possible. We therefore studied the intraoperative vascular anatomy for constant vascular findings. A perforating artery of the Musculus transversus nasalis was identified at the nasal ala on the cleft side, which could be constrantly preserved after it became aware.
The aim to refine a surgical treatment should not exclusively focus on the surgical technique but need also consider the burden of the entire treatment plan. More than 95% of the European cleft surgery centers use 2 to 4 surgeries to close the cleft of the lip, alveolus, hard, and soft palate –considering that this optimizes growth of the cleft maxilla. But facing the burden of repetitive surgeries for patient and family, Dr. Honigmann introduced in Basel 1991 the cleft repair in one single operation at “one-stage”. We were now able to assess the long-term growth effect of this procedure, which showed the same growth results as compared to multi-stage procedure. But when compared to normal, 20% to 45% of the cleft patients still showed a growth deficit that would require surgery to normalize the dental relation and facial profile. The orthognathic surgery rate in cleft patients from the literature ranges also widely from about 20% to 45%, whatever surgical technique and treatment plan is applied. It is therefore doubtful that by surgical means alone the growth deficit can be avoided. This prompted us to assess the in-vitro and in-vivo osteogenic capacity of stem cells from the umbilical cord Wharton’s jelly (WJMSC) under fully defined conditions allowing for clinical translation. Due to prenatal ultrasound the cleft lip malformation is frequently known before birth, and the umbilical cord could thus serve as an autologous stem cell donor site without any harvesting morbidity. Both, Osteogenically differentiated WJMSCs and WJ tissue biopsies produced a mineralized extracellular matrix. The expression of genes of osteoblastic lineage increased significantly after 3 weeks of osteodifferentiation. Although the WJMSCs formed in-vitro a dense collageneous matrix with signs of osteoblastic differentiation, no mature bone tissue was found after 8 weeks after subcutaneous implantation in immunoincompetent mice. Further in-vivo tests are therefore necessary applying more favorable bone forming conditions by using ostegenic predifferentiated cells and implantation into a bone defect.
In sum, biomedical and engineering methods have been applied to solve surgical problems or to establish new therapeutic strategies where conventional lip and nose reconstruction methods reach their limits. This has been demonstrated at different lip and nose reconstructive levels reaching from prosthetics, over microsurgery, to stem cell tissue engineering.