Reconstructive Surgery of Defects of the Lower Jaw

Настоящая диссертация посвящена разработке и клиническому внедрению комплекса методов реконструктивной хирургии приобретённых дефектов нижней челюсти и мягких тканей нижней зоны лица. В работе обоснованы показания к микрохирургическому замещению дефектов с использованием реваскуляризированных аутотрансплантатов, разработаны способы выбора донорских участков в зависимости от размера и локализации дефекта, а также предложены методы одномоментного вживления дентальных имплантатов и применения эндопротезов височно-нижнечелюстного сустава. Исследована степень остеоинтеграции имплантатов в реваскуляризированных костных аутотрансплантатах и ближайшие с отдалёнными результаты комплексного лечения. Предложена рабочая классификация приобретённых дефектов нижней челюсти.

The dissertation is devoted to the development and clinical implementation of a comprehensive system of reconstructive surgery for acquired defects of the lower jaw and soft tissues of the lower facial region. The study establishes indications for microsurgical replacement of defects using revascularized autografts, develops methods for selecting donor sites based on the size and location of the defect, and proposes techniques for one-stage implantation of dental implants and application of temporomandibular joint endoprostheses. The process of osseointegration of implants in revascularized bone autografts was investigated, along with immediate and remote outcomes of comprehensive treatment. A working classification of acquired defects of the lower jaw was proposed.

Relevance of the problem. At present, questions of surgical treatment of patients with defects and deformities of organs and tissues of the maxillofacial region remain an unresolved problem. This is associated with an increase in the number of patients with defects and deformities of the lower facial zone as a result of non-ballistic and ballistic injuries, as a consequence of osteomyelitis of the lower jaw, and after oncological operations [35,46, 69, 72, 75, 144, 145, 185, 190, 192, 194, 213, 237, 244, 253, 255].

Traditionally, for replacement of defects of the lower jaw, avascular autografts, formalinized or lyophilized allografts, and their combination (autoallotransplantation) or combined osteoplasty are used [4, 57, 72, 90, 93]. Although the technical performance of operations for replacement of defects of the lower jaw by these methods is not difficult, they are not devoid of disadvantages. The main disadvantages of avascular bone transplants are rejection, frequent resorption, difficulty in fixing a removable prosthesis during the rehabilitation period, etc. [10, 34, 108]. Moreover, after ballistic injuries and operative removal of malignant tumors, in addition to the defect of the lower jaw, extensive defects of soft tissues of the face are formed. The traditional method of surgical treatment of covering tissue defects is considered to be the use of a pedicled flap, which, along with advantages, has disadvantages: multi-stage nature, forced immobilization of extremities, and the danger of development of partial transplant necrosis at migration stages, etc. In the pocket thus created for the bone transplant, the latter takes hold and restructures worse, since the main source of osteogenesis — the periosteum — is absent in it [59,60].

In search of improving the results of surgical treatment, new technologies are widely introduced into practice. The introduction of microsurgical autotransplantation of tissue complexes has allowed replacement of extensive tissue defects with vascularized autografts [2, 7, 50, 59, 60, 92, 103, 127, 128, 131, 133, 157, 163, 164, 185, 188, 196, 198, 202, 211, 228, 233, 236,242,248,254].

The application of microsurgical technique makes it possible to replace complex composite defects of tissues of the lower facial zone in one stage, simultaneously eliminating defects of soft tissues and the lower jaw [19, 49, 64, 113, 137, 158, 187,201, 216, 217].

Analyzing the scientific information of domestic and foreign researchers, it becomes obvious that, despite the achieved successes in the field of surgery for elimination of defects of tissues of the maxillofacial region, the problem of functional rehabilitation of patients with defects of the lower jaw remains unresolved to the end. Operative interventions using microsurgical technique are applied increasingly often in practice and require improvement. One of the directions for solving this problem is the replacement of extensive defects of the lower jaw with one-stage implantation of dental implants and the use of temporomandibular joint endoprostheses. These questions remain insufficiently studied and represent a significant scientific and practical interest.

Goal of the research. Development of a system of methods for primary and delayed elimination of acquired defects of the lower jaw and soft tissues of the lower facial region using revascularized autografts on microvascular anastomoses with metallic implants implanted into them.

Research tasks: 1. Based on own clinical material and scientific publications, to evaluate the results of traditional methods for elimination of acquired defects of the lower jaw.

2. To develop a working classification of acquired defects of the lower jaw to substantiate surgical treatment methods and stomatological orthopedic rehabilitation of patients.

3. To determine indications for the microsurgical method of replacement of defects of the lower jaw and the lower facial zone.

4. To substantiate the choice of a donor body site for forming a revascularized autograft depending on the size and location of the defect of the lower jaw.

5. To develop and implement in clinical practice new methods of operative treatment of patients with terminal defects of the lower jaw.

6. To determine the degree of osseointegration of dental implants, primarily and delayedly implanted into autografts with axial type of blood supply, and to identify the most optimal terms for prosthesis of the lower jaw dentition.

7. To conduct a clinical analysis of immediate and remote results of comprehensive surgical and stomatological orthopedic treatment of patients with defects of bone and soft tissues of the lower facial zone and the lower jaw dentition.

Scientific novelty.

1. Indications for the microsurgical method of replacement of defects of the lower jaw have been determined; types and methods of extraction of revascularized bone autografts have been chosen depending on the location, size, and shape of the defect of the lower jaw.

2. A method of reconstruction of the lower jaw using a cutaneous-muscular-bone autograft from the medial border of the scapula has been developed and applied in clinical practice.

3. Theoretical substantiation and application of a revascularized osteocutaneous autograft including a fibula fragment for elimination of defects of the lower jaw and soft tissues of the lower facial zone have been provided.

4. For the first time, the defect of the lower jaw and soft tissues of the lower facial zone has been eliminated using a free revascularized osteocutaneous flap from the leg at vascular microanastomoses with dental implants implanted into the fibula fragment.

5. For the first time, for restoration of a distal defect of the lower jaw and arthroplasty, a free osteocutaneous autograft from the fibula at vascular microanastomoses with a titanium construction of a unipolar temporomandibular joint and implanted dental implants has been applied.

6. For the first time, the process of osseointegration of dental implants implanted into free revascularized bone autografts at microvascular anastomoses in the defect of the lower jaw and soft tissues of the lower facial zone has been investigated.

Practical significance of the work.

In practical terms, the significance of clinical and accessible methods of examination of patients with defects of the lower jaw for preoperative preparation and postoperative management has been demonstrated.

The results of scientific research demonstrate the advantages of the microsurgical method for elimination of defects of tissues of the lower facial zone compared to traditional ones.

Indications for the microsurgical method of replacement of defects of the lower jaw and the lower facial zone have been developed.

Methods for one-stage elimination of defects of the lower jaw and implantation of dental implants at the site of absent teeth of the lower jaw have been developed.

A working classification of acquired defects of the lower jaw has been compiled.

Methods for elimination of terminal defects of the lower jaw using titanium endoprostheses, a revascularized metatarsophalangeal joint of the II toe of the foot, and, for extended terminal defects of the lower jaw, an original method of plastic surgery with revascularized bone autografts in combination with endoprostheses of the lower jaw have been proposed.

Basic provisions of the dissertation submitted for defense:

1. Comprehensive clinical examination of patients with defects of the lower jaw and the lower facial zone of various location and extent by modern methods (angiography, ultrasonic Dopplerography, computed tomography) allows correct assessment of the choice of reconstructive-restorative treatment.

2. Application of traditional methods for elimination of defects of the lower jaw and the lower facial zone in combined defects, especially after ballistic injuries and resections for malignant neoplasms, increases the probability of unfavorable outcomes. In such situations, microsurgical autotransplantation of tissue complexes is indicated.

3. Use of a relocated (non-free) complex autograft from the medial border of the scapula on the transverse artery and vein of the neck allows achievement of replacement of combined defects of the lower facial zone.

4. Using free revascularized bone autografts in combination with dental implants makes it possible to simultaneously eliminate defects of the lower jaw and prepare the patient for further functional treatment, thereby accelerating the rehabilitation period.

5. Use of free revascularized bone autografts in combination with unipolar titanium endoprostheses of the temporomandibular joint allows replacement of the defect of the lower jaw and restoration of temporomandibular joint function.

6. Careful preoperative planning and observance of certain technical rules, as well as proper postoperative care taking into account the specifics of the maxillofacial region and the biomechanics of the lower jaw allow minimizing the probability of postoperative complications both from the recipient area and the donor site.

Volume and structure of the dissertation. The dissertation is written in Russian. It consists of an introduction, 6 chapters of own observations, discussion of the obtained results, conclusion, conclusions, practical recommendations, and a list of references. The work is presented on 227 pages of typed text, includes 109 figures and 23 tables. The list of references consists of 259 sources. The last includes 101 works by domestic and 158 works by foreign authors.