Experimental reconstruction of the mandibular joint

Modified Osteotomy for TMJ Ankylosis in Paediatric Patients with Deficient Interpositional Temporalis Muscle Mass and Buccal Fat Pad - A case Series and Literature Review

Ankylosis of the temporomandibular joint (TMJ) is a bony or fibrous fusion of the articular surfaces of the mandibular condyle and the glenoid fossa. Gap arthroplasty, Interpositional arthroplasty, Condyle reconstruction with autogenic or alloplastic grafts and total joint replacement are some common modalities of management. In this article, we discuss a series of three cases of unilateral TMJ ankylosis in paediatric patients, managed by gap arthroplasty using a modified osteotomy cut. The modification was adapted due to inadequate interpositionable temporalis muscle or buccal fat on the affected side and chances of adaptive remodelling of the CCG (Costochondral graft), if placed were rendered negative.

Biomechanical analysis of costochondral graft fracture in temporomandibular joint replacement

This study is the first attempt to explore the reason of costochondral graft fracture after lengthy mandible advancement and bilateral coronoidectomy by combining finite element analysis and mechanical test. Eleven groups of models were established to simulate costochondral graft reconstruction in different degrees of mandible advancement, ranging from 0 to 20 mm, in 2 mm increment. Force and stress distribution in the rib-cartilage area were analyzed by finite element analysis. Mechanical test was used to evaluate the resistance of the rib-cartilage complex. Results showed a sharp increase in horizontal force between 8 and 10 mm mandible advancement, from 26.7 to 196.7 N in the left side, and continue increased after 10 mm, which was beyond bone-cartilage junction resistance according to mechanical test. Therefore, we concluded that bilateral reconstruction with coronoidectomy for lengthy mandible advancement (≥ 10 mm) may lead to prominent increase in shear force and result in a costal-cartilage junction fracture, in this situation, alloplastic prosthesis could be a better choice. We also suggested that coronoidectomy should be carefully considered unless necessary.

Leveling the Maxillary Occlusal Plane Without Orthodontic Appliances in Patients With Hemifacial Microsomia Using Unilateral Vertical Mandibular Distraction Osteogenesis

PURPOSE

To assess maxillary occlusal plane correction in patients with hemifacial microsomia (HFM) after vertical vector mandibular distraction osteogenesis (vMDO) without orthodontic appliances.

METHODS

A retrospective study was performed on consecutive patients with HFM and Kaban-Pruzansky type-II mandibular deformities who underwent unilateral vMDO by a single surgeon over an 18-month period. Patients with 12-months minimum clinical follow-up and postero-anterior (PA) cephalograms taken preoperatively and at a minimum of 3 months post-consolidation were included.

RESULTS

Five patients met inclusion criteria, 3 were female, median age was 13 years, median distraction length was 21.3 mm. Median radiographic follow-up was 5 months (range 3-38) post-consolidation. Median correction of the ramus height differential (difference between non-diseased and diseased side) was 97.3%. Median maxillary height differential correction was 72.2%. Median maxillary occlusal plane angle correction (towards zero) was 84.2%. Relative and absolute maxillary bone growth was greater on the diseased side (median 7.4%, 3.5 mm versus 2.8%, 1.4 mm). Dentoalveolar height decreased bilaterally in 4 of the 5 patients. Median chin point correction (towards midline) was 31.4%.

CONCLUSION

Unilateral vMDO without orthodontic appliances effectively corrected mandibular ramus height, leveled the maxillary occlusal plane, and preferentially increased maxillary bone growth on the diseased side in patients with HFM.

Interpositional Arthroplasty by Temporalis Fascia Flap and Galea Aponeurotica Combined With Distraction Osteogenesis: a Modified Method in Treatment of Adult Patients With Temporomandibular Joint Ankylosis and Mandibular Dysplasia

BACKGROUND

Interpositional arthroplasty (IPA) with temporalis fascia flap has been one of the most frequently performed procedures to treat temporomandibular joint (TMJ) ankylosis. However, recurrence often occurs when the flap lacks bulk or atrophies. Whether to perform IPA or distraction osteogenesis (DO) first has long been a controversial issue when patients presented mandibular dysplasia (MD). This study provided IPA a new graft material sufficient to prevent recurrence, combined the modified protocol of performing DO 6 months after IPA, and evaluated its efficacy in treating TMJ ankylosis patients with MD.

METHODS

Six patients with unilateral TMJ ankylosis and MD were treated in the authors' study. The temporalis fascia flap and part of adjacent galea aponeurotica were filled the space after surgical release. Mouth-opening exercises started immediately post-IPA. Distraction osteogenesis was performed 6 months after IPA and had a 4-month consolidation. The maximum interincisal distance at preoperative, immediately post-IPA and the latest follow-up were recorded, as was the distraction length. The body mass index was measured at each patient's postoperative visit.

RESULT

All patients had significant improvements in facial aesthetic, mouth-opening, and occlusion. No major complication or recurrence was observed at 3 to 4 years' follow-up. The mean maximum interincisal distance was 4.83 ± 2.79 mm preoperative and 35.67 ± 3.39 mm at the latest follow-up. The mean distraction distance was 16.17 ± 5.98 mm. The body mass index improved from 17.33 ± 0.64 kg/m preoperative to 18.75 ± 0.60 kg/m before DO.

CONCLUSIONS

Temporalis fascia flap and adjacent galea aponeurotica as new graft materials are recommended for IPA. The modified staged treatment proved to be reliable and effective to prevent recurrence, improve mandibular length and final occlusion.

Costochondral Graft Versus Total Alloplastic Joint for Temporomandibular Joint Reconstruction

Presently, there are 2 options for the replacement of the temporomandibular joint for end-stage pathology: autogenous bone grafting or alloplastic joint replacement. This article presents evidence-based advantages and disadvantages for each of these management options to assist both surgeons and their patients in making that choice.

Formation of Condyle-Like Structure after Treatment of Temporomandibular Joint Ankylosis: Literature Review and Long-Term Follow-Up of Two Patients

Treatment of ankylosis is one of the greatest challenges in temporomandibular joint (TMJ) surgery. To provide a satisfactory mouth opening, as well as normal jaw function, and to prevent reankylosis in the long term are the most important principles in the treatment of TMJ ankylosis. These functions have been attained in both of the presented patients in the long term. It is known that heterotopic bone formation is rare in the maxillofacial area, but rapid bone regeneration which reconstitutes a new condyle is rarer. The purpose of the presented paper is to reveal the existence of an inherent capability of the mandible, rapid bone growth of the ramus mandible, and reformation of a previously nonexisting condyle after resection of the ramus in patients with TMJ ankylosis. In this paper, two unusual cases of unexpected condyle-like structure formation after treatment of ankylosis were presented.

Mandibular Reconstruction: Overview

INTRODUCTION

Mandibular reconstruction has changed significantly over the years and continues to evolve with the introduction of newer technologies and techniques.

PURPOSE

This article reviews the history of oromandibular reconstruction, biomechanics of mandible, summarizes the reconstruction options available for mandible with defect classification, goals in reconstruction, the various donor sites, current reconstructive options, dental rehabilitation and persistent associated problems.

SUMMARY

Oromandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes with the use of autogenous bone grafts and current reconstructive options. The ideal reconstruction would provide a solid arch to articulate with the upper jaw, restoring swallowing speech, mastication, and esthetics. Autogenous vascularized bone grafts in combination with microsurgical techniques have revolutionized mandibular reconstruction in oral cancer surgery. Current trends in mandibular reconstruction aim to achieve reestablishment of a viable mandible of proper form and maxillary mandibular relationship while decreasing the need for invasive autogenous graft procurement. However the optimal reconstruction of mandibular defects is still controversial in regards to reconstructive options which include the donor site selection, timing of surgery and method of reconstruction.

Silicone vs temporalis fascia interposition in TMJ ankylosis: A comparison

OBJECTIVE

Temporomandibular joint ankylosis (TMJa) is a distressing condition, but can be surgically managed by gap or interpositional arthroplasty, with an aim to restore joint function and prevent re-ankylosis. The aim of this paper is to compare two interposition materials used in management of TMJ ankylosis.

METHODS

15 patients with TMJa were randomly allocated to two groups: group A (n = 6), interposition material used was medical-grade silicon elastomer, and group B (n = 9) where the interposition material used was temporalis fascia. Patients were followed up at regular intervals of 1 and 2 weeks, 1 month, 3 months, and 6 months and were assessed on following parameters: pain by VAS Scale, maximal mouth opening (MMO), implant rejection, and recurrence.

RESULTS

The results showed a loss of 4.6% and 7.9% in maximal interincisal mouth opening at 3rd and 6th months in Group A while Group B had a mean loss of 9% and 10% at 3rd and 6th months respectively without any significant difference. None of our cases showed recurrence or implant rejection.

CONCLUSION

We conclude that silicone is comparable to temporalis fascia in terms of stability, surgical ease, and adaptability. It not only restores the function of mandible and ensures good maximum interincisal opening but also maintains the vertical ramal height. Also, it requires less operating time and is easy to handle but is not economical. It might be an effective way to restore function and prevent re-ankylosis.

Unilateral mandibular hypoplasia in adult patients: distraction osteogenesis and conventional osteotomies in a standardized sequence

INTRODUCTION

This study analyzed the outcomes of nongrowing patients with unilateral mandibular hypoplasia treated according to a specific protocol, which combines distraction osteogenesis, orthodontic treatment, and conventional osteotomies.

MATERIALS AND METHODS

The patients treated were objectively evaluated. Patient's satisfaction was assessed by questionnaire. Surgical changes were analyzed using cephalometry and three-dimensional facial surface data before surgery (T0) and at long-term (T1) follow-up.

RESULTS

Four patients were included in this study. The normalization of facial proportion and a high increase in symmetry were evident. Residual defects were documented in the postoperative symmetry of the chin. In the questionnaire, all patients gave favorable responses to their facial changes; for most of the objective parameters, all patients improved.

CONCLUSIONS

A multistage treatment protocol for the correction of facial deformities in patients with unilateral mandibular hypoplasia is a valid procedure for skeletal and occlusal stability. An evident improvement of the facial appearance is also achieved.

Professor David Poswillo CBE (1927-2003): Skilled oral and maxillofacial surgeon, influential scientist, teacher and adviser

David Poswillo trained at Otago University Dental School, Dunedin, New Zealand (BDS) and the Royal College of Surgeons of England (FDSRCS). His great interest became the genesis and repair of cleft lip and palate and, in addition to clinical work, he undertook an experimental study of the embryology of cleft palate in pregnant rats exposed to three teratogenic agents. The microscopic work was carried out in his garden shed in Christchurch. His groundbreaking work on amniotic puncture at a critical period came to international notice and he was given the first Chair in Teratology of the Royal College of Surgeons. In experimental studies he showed that thalidomide induced focal haemorrhage in the developing embryo. Poswillo was also Consultant Oral Surgeon at Queen Victoria Hospital, East Grinstead and his skills as surgeon and teacher attracted numerous trainee surgeons. He was Professor of Oral Surgery in Adelaide and then in London. Poswillo was Chairman of two advisory committees whose lucid reports on anaesthesia, sedation and resuscitation in dentistry (Poswillo Report) and on tobacco and health were far-reaching and influential. David Poswillo had immense energy and enthusiasm and is remembered by many for his personal interest and stimulating guidance.

Enhancing post-expansion chondrogenic potential of costochondral cells in self-assembled neocartilage

The insufficient healing capacity of articular cartilage necessitates mechanically functional biologic tissue replacements. Using cells to form biomimetic cartilage implants is met with the challenges of cell scarcity and donor site morbidity, requiring expanded cells that possess the ability to generate robust neocartilage. To address this, this study assesses the effects of expansion medium supplementation (bFGF, TFP, FBS) and self-assembled construct seeding density (2, 3, 4 million cells/5 mm dia. construct) on the ability of costochondral cells to generate biochemically and biomechanically robust neocartilage. Results show TFP (1 ng/mL TGF-β1, 5 ng/mL bFGF, 10 ng/mL PDGF) supplementation of serum-free chondrogenic expansion medium enhances the post-expansion chondrogenic potential of costochondral cells, evidenced by increased glycosaminoglycan content, decreased type I/II collagen ratio, and enhanced compressive properties. Low density (2 million cells/construct) enhances matrix synthesis and tensile and compressive mechanical properties. Combined, TFP and Low density interact to further enhance construct properties. That is, with TFP, Low density increases type II collagen content by over 100%, tensile stiffness by over 300%, and compressive moduli by over 140%, compared with High density. In conclusion, the interaction of TFP and Low density seeding enhances construct material properties, allowing for a mechanically functional, biomimetic cartilage to be formed using clinically relevant costochondral cells.

Overgrowth of costochondral graft in temporomandibular joint ankylosis: An unusual case

Costochondral graft (CCG) replacement of the mandibular condyle was first described by Gilles in 1920. Since then CCGs have gained increasing popularity in reconstruction of the TMJ and condyle in children. The influence of CCGs on mandibular growth and function is not known in detail. Adaptation of the graft has been observed to be better in children, but CCGs have also been shown to grow in adult patients. One of the major disadvantages of the CCGs is its growth pattern, which is extremely unpredictable and may manifest as excessive growth or no growth at all. A mandibular overgrowth on the grafted site can actually be more troublesome than lack of growth. Furthermore, maxillary growth is proportionality influenced by vertical mandibular growth of the graft. This is a report of such a case in which a bizarre overgrowth of the graft was seen following a reconstruction of TMJ by CCG and the devastating outcomes of the treatment. He required one further resection because the grafted tissue had overgrown five years later.

Autogenous grafts for condylar reconstruction in treatment of TMJ ankylosis: current concepts and considerations for the future

Temporomandibular joint (TMJ) ankylosis is characterized by difficulty or inability to open the mouth due to fusion of the temporal and the mandible, resulting in facial symmetry/deformity, malocclusion and dental problems. The only treatment option for TMJ ankylosis is surgical with or without condylar reconstruction. Various autogenous grafts are available for condylar reconstruction after freeing the ankylotic mass such as costochondral, sternoclavicular, fibular, coronoid, and metatarsophalangeal. Costochondral graft is preferred by surgeons, but distraction osteogenesis is slowly gaining popularity and may ultimately become the standard procedure, providing a cost-effective approach with low morbidity and excellent functional outcomes. Tissue engineering is another budding field which has shown promising results in animal studies but has not been applied to humans. To date, there is no ideal autogenous graft for condylar reconstruction that satisfies the complex anatomy and the myriad of functions of a missing condyle.

Interposition arthroplasty in post-traumatic temporomandibular joint ankylosis: A retrospective study

Temporomandibular joint ankylosis which is most frequently caused by trauma, presents with restriction in mouth opening in early stages and if children are the victim and not treated early, it presents with growth retardation of the involved mandibular side. Various methods are available for surgical correction. We have reviewed our experience with the efficacy of different interpositional materials in post-traumatic cases in our set up with special reference to temporal fascia over last three years. Twenty seven patients with history of trauma, mostly fall from height, have been studied. They were evaluated clinically and by computed tomography (CT) scan, orthopantogram and x- ray lateral oblique view. The most common age group was 10-15 years with mean 12.5 years and male to female ratio 1:2. Preoperative mouth opening (inter incisor distance) was 1-2 mm in 17 cases and 2-4 mm in 10 cases. We have used temporalis fascia in nine, costochondral graft in seven, silastic sheets in five and T-plates in six cases. Post-operatively, adequate mouth opening of 30-50 mm was observed in six months follow-up and more than 50 mm at one year follow up in 21 cases out of which nine cases have interpositional material as temporalis fascia alone. The postoperative period was uneventful in all cases and none required re-operation for recurrences. We conclude that interpositional arthroplasty, especially with pedicled temporal fascia, is the best method to prevent recurrences and establish good mouth opening and full range of jaw movements.

Reappraisal of the surgical strategy in treatment of mandibular condylar fractures

BACKGROUND

Over the past few decades, there has been a trend toward open reduction and internal fixation of mandibular condylar fractures. However, not all patients have fared well following the open surgical approach. A number of clinical parameters have been observed to be related to suboptimal treatment results on a long-term basis. A comprehensive investigation of the role of those risk factors is a worthwhile pursuit.

METHODS

A total of 23 surgically treated patients were enrolled in the study during an 11-year period. A retrospective chart review was conducted to collect clinical and radiographic information both before and after surgery. Statistical analyses were used to determine the relationship of presurgical clinical variables to the postsurgical complications.

RESULTS

Fractures of the condylar neck and head were associated with a high incidence of postoperative morbidity; all cases (seven of seven) suffered from some form of image or clinical disorder. In contrast, the subcondylar fracture fared well following surgery, with maintenance of function, cosmesis, and skeletal integrity in the majority (14 of 16) over long-term follow-up (p < 0.000). Comminution and obliquity of the fracture line were also correlated with the occurrence of postoperative morbidities.

CONCLUSIONS

Results of the present study suggest that patients with subcondylar fracture fare better with open reduction in comparison with those suffering condylar neck or head fractures. Delayed-onset deformation tends to occur in patients with a short proximal segment, comminuted head, and obliquity of the fracture line. A renewed algorithm is thus provided to address the high condylar fracture problems.

Bidirectional temporomandibular joint ankylosis: a rare, disabling condition of mastication

Temporomandibular joint (TMJ) ankylosis is characterized by a bony mass that generally creates difficulty in 1 direction, opening the mouth. In this paper, the patient who presented was experiencing difficulty in 2 directions, both in opening and closing the mouth. A rare disabling condition of mastication and bidirectional ankylosis and its surgical treatment have been presented. Bidirectional temporomandibular joint ankylosis is a rare condition that disables the patient both to open and close the mouth. The left side of type 2 ankylosis (Sawhney, Plast Reconstr Surg 1986;77:29-38) was treated conservatively. Disc was preserved and used as interpositional material. In treatment of the right side, which was type 4 ankylosis (Sawhney, Plast Reconstr Surg 1986;77:29-38), a gap was created, and then, a titanium fossa implant was placed to prevent ankylosis.

Surgical Induction of Temporomandibular Joint Ankylosis: An Animal Model

PURPOSE

The aim of this study was to develop an animal model of temporomandibular joint (TMJ) bony ankylosis for future evaluation of surgical reconstructive methods.

MATERIALS AND METHODS

An animal model was selected on the basis of 2 sequential experiments. Four goats and 4 minipigs were used in the first experiment, in which 1 goat and 1 minipig served as control animals. Condylectomy with disc preservation was performed on 1 side of 3 animals in each group. On the contralateral TMJ, condylectomy with discectomy was performed, and the arthroplasty gap was filled with the autogenous bone chips. In the second experiment, TMJ ankylosis was induced bilaterally in 3 additional animals of the species that achieved better ankylosis results in the first experiment. All animals were killed postoperatively at 3 months, and the TMJ complexes were examined by plain radiography, computed tomography, and histological evaluation.

RESULTS

In the first experiment, only fibrous ankylosis was observed in the bone-grafted side of 2 goats and 3 minipigs, whereas fibro-osseous ankylosis was achieved in the remaining goat. The extent of ankylosis was found to be more severe in the goats than the minipigs. Hence, goats were selected for bilateral surgery in the second experiment, which achieved consistent bony ankylosis of the TMJ in all animals.

CONCLUSIONS

Goats provide a better TMJ bony ankylosis model than minipigs. Consistent bony ankylosis can be induced by bilateral condylectomy, disectomy, and bone grafting of the arthroplasty gap.

Two-stage Treatment of TMJ Ankylosis by Early Surgical Approach and Distraction Osteogenesis

Temporomandibular joint (TMJ) ankylosis is characterized by the formation of bone or fibrous adhesion of the anatomic joint components, which replaces the normal articulation and limitation of mouth opening. Early surgical intervention is considered as a treatment procedure to release the joint ankylosis and to maintain the function of the joint. Longstanding temporomandibular joint ankylosis which starts during the active growth period in early childhood resulting in facial asymmetry. Thus, the importance of the evaluation for the facial asymmetries and unfavorable remodeling of the mandible has to be considered during the initial treatment planning. Further operations, either osteotomies or distraction osteogenesis, are required for the treatment of maxillofacial deformities. The present study reports a case of unilateral TMJ ankylosis treated by interpositional arthroplasty prior to distraction osteogenesis for the treatment of mandibular secondary deformity. Various treatment procedures and timing protocols are reviewed and discussed.

The Effect of Autogenous Costochondral Grafts on Temporomandibular Joint Fibrous and Bony Ankylosis: A Preliminary Experimental Study

PURPOSE

The purpose of this study was to test the functional and histologic fate of costochondral grafts (CG) in temporomandibular joint (TMJ) reconstruction for unilateral ankylosis in the sheep.

MATERIALS AND METHODS

Five pure-bred adult Merino sheep were used. Ankylosis was induced by articular damage, disc removal, and placement of a bone graft. At 3 months, a gap arthroplasty was performed with a CG from the thirteenth rib. The sheep were sacrificed 3 months after CG reconstruction. The range of jaw movements were recorded at first operation, at lysis of ankylosis, and at sacrifice. The joints were examined radiologically, macroscopically, and histologically.

RESULTS

All sheep showed a decrease in masticatory function, as shown by weight loss and decreased jaw opening, during the ankylosis period. On release, they regained weight and increased the range of jaw movement. Histologically, the joint space was filled with fibrous tissue. However, the partial spaces around the CG head were covered by fibrous tissue and/or fibrous cartilage.

CONCLUSIONS

This study shows that, when CGs are used with a gap arthroplasty in a fibrous and bony ankylosed TMJ, masticatory function is restored.

Treatment of temporomandibular joint ankylosis in children: is it necessary to perform mandibular distraction simultaneously?

Temporomandibular joint (TMJ) ankylosis in children disturbs not only mandibular growth, but also facial skeletal development. Costochondral graft was used to ensure growth, but it had proven to be unpredictable. The authors evaluate retrospectively 41 patients who underwent temporomandibular joint reconstruction during the last 10 years. Twenty were treated by costochondral graft, 15 by arthroplasty, and 6 by other surgical procedures, and they were excluded. The etiology was septic in 54% of the cases. Follow-up was at least 12 months in all cases. Arthroplasty was a quicker and easier procedure than the costochondral graft, reducing operating time, risk of blood transfusion, and hospital stays and costs. It also was associated with less risk of reankylosis, 13%vs 25%. Furthermore, it was associated with a minor morbidity and secondary complications. Seventy-five percent of the patients treated with bone graft required additional secondary surgery. Radiographically, the authors observed a remodeled neocondyle at the level of proximal mandibular end in cases treated by arthroplasty. On clinical examination, patients showed variable degrees of facial deformity and an unknown potential of mandibular growth after TMJ arthroplasty. The authors also observed improved clinical and radiologic appearance after ankylosis correction. Is it reasonable to perform ankylosis release and mandibular distraction simultaneously without knowing which patients will be able to experience growth with time? In that case it would be necessary a predict growth to apply the exact amount of mandibular distraction for obtaining stable results. Timing of mandibular distraction, after TMJ arthroplasty is performed and mandibular function restored, must be specific to each patient's needs, assuring the best distraction conditions and planning. The authors present their treatment protocol, including TMJ joint arthroplasty with temporal muscle interposition, and mandibular distraction osteogenesis, as a second procedure, to correct residual asymmetry or retrognathism if necessary.

Growth of the mandible after replacement of the mandibular condyle: an experimental investigation in Macaca mulatta

PURPOSE

The study goal was to investigate growth of the mandible after temporomandibular joint reconstruction in juvenile monkeys.

MATERIALS AND METHODS

Sixteen juvenile monkeys (Macaca mulatta) were used as experiment subjects. Animals were equally divided into 4 experimental groups based on the method of temporomandibular joint reconstruction after bilateral condylar excision via extraoral vertical ramus osteotomies. Group Condyle animals had their condylar segments immediately replaced to serve as surgical controls. Group Bone animals were reconstructed with a bony strut. Group sternoclavicular joint (SCJ) animals were reconstructed with the sternal end of their clavicles. Group costochondral junction (CCJ) animals were reconstructed with costochondral junction of ribs. Standardized lateral cephalometric radiographs with the aid of tantalum bone markers were used to evaluate mandibular growth. Twenty animals were used as controls and were allowed to grow undisturbed for an 18-month period (Group Control).

RESULTS

All animals showed good mandibular function and a Class I molar relationship after an 18-month follow-up period. Statistical and graphic comparisons showed no significant difference in mandibular growth among any of the groups.

CONCLUSIONS

The results of this investigation suggest that, within the limits of this model, the choice of autograft for condyle replacement may be irrelevant.

Histology of surgically removed overgrown osteochondral rib grafts

INTRODUCTION

Osteochondral rib grafts are most commonly used for mandibular condylar replacements. However, when used in growing patients, unpredictable growth of the constructed condyle/ramus is a common complication. Clinically two types of overgrowth, linear or exuberant, have been described.

PURPOSE

In order to investigate growth disorders associated with osteochondral rib grafts in children, overgrown grafts were examined histologically.

PATIENTS AND METHODS

The material consisted of seven samples (six patients) of osteochondral rib grafts, that had been removed due to overgrowth.

RESULTS

Examination revealed that the clinical type of overgrowth was not related to any specific microarchitecture, which in itself, showed considerable variation. In three of the samples, a typical endochondral ossification zone was seen and in two others, signs of metaplasia, i.e. a gradual transformation of the cartilage cells into osteocytes, were noted.

CONCLUSIONS

The study reveals that the clinical type of overgrowth, linear or exuberant, cannot be related to any typical histological finding. Furthermore, the findings suggest that local factors, such as mandibular movements and loading of the reconstructed condyle may have an effect on the structure of the osteochondral rib graft, and eventually on its growth.

The effect of a unilateral costochondral graft on the growth of the marmoset mandible

PURPOSE

The purpose of the investigation was to examine growth of the mandible after costochondral grafting with special reference to the amount of cartilage included in the grafts.

MATERIALS AND METHODS

The material consisted of 5 growing and 3 adult marmoset monkeys, Callithrix jacchus, in which the condylar process was removed unilaterally and replaced with a costochondral graft (CCG) containing either a short or long cartilage end. Growing animals were followed for 15 months until they attained maturity; and adult animals were followed for 13 months. Measurements made on frontal radiographs performed bimonthly, and direct measurements made on dry mandibles and crania at the end of the experiment, were used to evaluate the growth of the mandible and glenoid fossa.

RESULTS

Longitudinal cephalometric evaluation revealed a gradual deviation of the lower dental midline to the unoperated side in growing monkeys with a long cartilage transplant. In all other animals, virtually no midline deviation occurred. Measurements on dry mandibles showed that the length and ramus height were longer in growing animals with long cartilage transplants compared with those with short cartilage transplants. In adult animals, the amount of cartilage did not make any difference with regard to the mandibular measurements. Enlargement of the articulating head on the grafted side was recorded in all animals. A morphologic change in the glenoid fossa of growing monkeys with a long cartilage transplant was also noted.

CONCLUSIONS

The findings of this investigation indicate that depending on the amount of cartilage in a unilateral CCG, a tissue-separating force is generated in growing monkeys, capable of propelling the mandible to the unoperated side. This gradual overgrowth occurs during the entire growth period, indicating a strong hormonal and growth factor influence on the growth process. Jaw function may have an effect on the articulating surface of the CCG, seen as enlarged articulating head on the grafted side in all animals.

Is early osteodistraction a solution for the ascending ramus compartment in hemifacial microsomia? A literature study

AIM

In hemifacial microsomia, osteodistraction before skeletal maturation claims to induce both bone- and soft-tissue generation in such a way that conventional bone grafting and soft-tissue grafts are not necessary. Early osteodistraction in facial microsomia would have a positive effect on the 'functional matrix', and allow symmetrical vertical and sagittal expansion of the midface and mandible. The aim of this literature survey was to find evidence for this hypothesis by analysing long-term follow-up reports on distraction histiogenesis in the ascending ramus.

MATERIAL

Only eight published studies were found, of which only two had more than ten patients, two were case reports, and three were from the same institution.

RESULT

Invariably, the results pointed towards over-correction, repeated osteodistraction procedures, soft-tissue stretching (but no lateral augmentation), and to soft-tissue complications. The studies did not allow a conclusion to be made as whether increased vertical gain in the ascending ramus was unstable because of decreased growth on the affected side, inborn or iatrogenic, or due to resorption of the bone generated by distraction. To date, there is no evidence that osteodistraction produces better results and has lower morbidity than conventional growth centre transplantation and separate soft-tissue augmentation.

CONCLUSION

Recommendations for prospective studies are: sharp differentiation between the four Pruzansky-Kaban mandibular types, multi-centre study of a surgical protocol to increase the sample number using a standard three-dimensional evaluation protocol, and differentiation between decreased growth and collapse of the newly generated bone.

Growth of costochondral grafts in reconstruction of the mandibular condyle: an experimental study in domestic pigs

Reconstruction of the mandibular condyle with costochondral grafts (CCGs) in children may result in overgrowth at the reconstructed side of the mandible. In this study we report on the effects of functional stimuli on growth and morphology of growth plates of CCGs used for immediate mandibular condyle replacement in 10 juvenile pigs. The mandibular condyles were resected unilaterally and immediately reconstructed with autogenous CCGs. Another CCG was placed submuscularly on one tibia. The lengths of both CCGs and of one rib before resection were measured at operation and 12 weeks later. The grafts were labelled with intraperitoneal injections of oxytetracycline and alizarin eight and 12 weeks postoperatively, respectively. The extent of growth of the CCGs in the two environments was similar, so we concluded that the functional stimuli in the TMJ environment had only a minor influence on the extent of growth of the CCGs. The morphology of the growth plate of the CCGs had changed considerably.

Unilateral mandibular condylectomy in lambs

The purpose of this experimental study was to investigate the degree of regeneration of the mandibular condyle after unilateral condylectomy in 10-week-old lambs. The lambs were killed three months after the operation, and the joints examined radiologically and histologically. Scoring systems were used to assess the radiological changes and histological regeneration of the condyle. All joints showed regeneration of the condylar head postoperatively. The maximum degree of regeneration occurred on the medial side rather than the central or lateral areas. There was a significant correlation among the medial, central, and lateral planes (P<0.05). The reformed articular cartilage was irregular and thin (P<0.01), and the disc was thick in the central plane (P<0.01) compared with the control joints. The temporal bone was normal. This study shows that unilateral condylectomy in the growing period results in some condylar regeneration particularly on the medial side and reformation of some irregular and thin articular cartilage.

Melanotic neuroectodermal tumor of infancy involving the mandible: 7-year follow-up after hemimandibulectomy and costochondral graft reconstruction

Oral and maxillofacial tumors occur rarely in the pediatric population compared with the adult population. We report a case of a 6-months old female infant suffering from a melanotic neuroectodermal tumor of infancy involving the mandible. Tumor resection was performed using a submandibular approach; the mandibular defect was reconstructed primarily with autogenous costochondral grafts. During a 7-year follow-up period, there has been no tumor recurrence. The costochondral graft healed well; tracing of panoramic radiographs at 2, 3, and 6 years documented some vertical overgrowth and growth retardation in the transversal dimension. The authors conclude that the use of costochondral grafts despite its controversial role for mandibular reconstruction can be recommended in particular after continuity resections in newborn infants. However, long-term follow-up is necessary as well as secondary corrective surgery at early skeletal maturity.

Costochondral grafts in reconstruction of the temporomandibular joint after condylectomy: an experimental study in sheep

The purpose of this study was to investigate the effect of costochondral grafts in the temporomandibular joint (TMJ) in sheep. Five pure-bred adult Merino sheep were used. The condyle alone was resected and replaced with a costochondral graft from the 13th rib. The sheep were killed 3 months after operation. The range of jaw movements before and after operation and at death were recorded. The joints were examined radiologically, macroscopically, and histologically. A new condylar head with normal configuration and function developed. Histologically, the chondrocytes were arranged in a fashion similar to that of a normal joint. All inferior joint spaces showed fibrous adhesions between the condylar head and disc. This study showed that, when such grafts are used to replace the condyle in an otherwise normal sheep TMJ, they fused to the ramus and reconstituted a nearly normal, fully functional joint.

Temporomandibular joint reconstruction in children using costochondral grafts

PURPOSE

The aim of this study was to evaluate the postoperative growth of the mandible after reconstruction of the condylar process using costochondral grafts in children.

PATIENTS AND METHODS

Temporomandibular joint (TMJ) ankylosis was surgically treated and the joint reconstructed with a costochondral graft (CCG) in two boys and eight girls with a mean age of 7.4 years. Two children had bilateral ankylosis. Postoperative changes and craniofacial growth were monitored by lateral and posteroanterior (PA) cephalograms annually from 2 to 6 years (mean of 4 years).

RESULTS

Postoperatively, in the eight children with unilateral TMJ reconstruction, the mandible (Co-Gn) grew an average of 14.7 mm in length on the affected side and 15.1 mm on the nonaffected side; ramus length (Co-Go) increased an average of 7.1 mm on the affected side and 7.3 mm on the nonaffected side. However, in five of the children the chin progressively deviated toward the nonaffected side after TMJ reconstruction. The CCGs tended to have a more vertically directed condylar growth pattern and a more laterally positioned condyle. In the two cases with bilateral TMJ reconstruction, the CCGs grew until there was a mandibular prognathism that required orthognathic surgery to set back the mandible.

CONCLUSIONS

Using CCGs to reconstruct TMJ ankylosis in children provides a functional condyle with growth potential. However, there is a possibility of excessive growth of the graft, resulting in deviation of the chin and mandibular prognathism years later.

Use of activator appliances in pediatric patients treated with costochondral grafts for temporomandibular joint ankylosis: analysis of 13 cases

PURPOSE

The long-term outcomes and clinical results of costochondral transplants used for the treatment of condylar ankylosis of the mandible in children with and without application of postoperative activator appliances are evaluated and compared.

MATERIALS AND METHODS

A nonrandomized, retrospective clinical study of 13 cases of condylar ankylosis (16 joints) of the mandible surgically treated during a 9-year period from 1988 to 1997 was performed. All 13 patients were treated by condylectomy and immediate costochondral rib grafts. Nine of these patients underwent long-term postoperative therapy using removable activator appliances. Four patients did not undergo activator therapy postoperatively. Casts, radiographs, photographs, computed tomography (CT) scans, magnetic resonance imaging (MRI) and 99Tc bone scans were used postsurgically to evaluate graft take, condylar growth and function, occlusion, and facial and condylar symmetry.

RESULTS

The postoperative and long-term clinical results in both groups showed costochondral growth center transplants to be effective in restoring mandibular growth of the affected side. However, symmetry, arch coordination, correction of occlusal canting, mandibular deviation, facial growth, and prevention of reankylosis were obtained and better controlled only in those cases that underwent long-term orthodontic activator therapy postoperatively and were followed closely.

CONCLUSIONS

Children with long-standing condylar ankylosis of the mandible and its resultant facial asymmetry and occlusal canting (secondary to a nonfunctional joint and maxillary compensation) treated with condylectomy and immediate costochondral rib graft reconstruction of the affected joint were treated more favorably when activators were used postsurgically. The patients that failed to comply with or continue activator therapy postsurgically developed complications relating to mandibular deviation, occlusal dysharmony, asymmetry and, in one case, reankylosis of the temporomandibular joint (TMJ).