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PubMedDate not supplied

The versatility of distraction osteogenesis in craniofacial surgery.

OBJECTIVES: To review our preliminary results using distraction osteogenesis for the correction of craniofacial deformities and to determine its role in treating anatomic deformities and functional deficits relative to conventional craniofacial surgery. DESIGN AND SETTING: Retrospective clinical review; tertiary care center. METHODS: Twenty-four consecutive patients were treated with distraction osteogenesis during a 34-month period. Outcomes were compared with preexisting anatomic deformities and functional deficits using records of clinical assessments, photodocumentation, diagnostic imaging, and treatment planning aids. MAIN OUTCOME MEASURES: Distraction achieved vs planned distraction based on clinical and radiographic assessment, clinical status of functional deficits before and after treatment, and objective rating of aesthetic improvement. CONCLUSIONS: Preliminary results demonstrated good-to-excellent outcome in correcting facial skeletal deformity in 80% of patients. Functional outcomes included resolution or significant improvement of upper airway obstruction in 13 of 14 patients and correction of corneal exposure for all 5 patients with preexisting exorbitism. Correction of malocclusion was less reliable. Problems related to the distraction devices, including failure of the advancement mechanism and fixation, were the most prevalent complications. Distraction osteogenesis represents an exciting new development in craniofacial surgery with several potential benefits, including less invasive surgery, the ability for earlier intervention, and the potential for correction of more severe deformities with improved posttreatment stability. The exact role of distraction osteogenesis relative to conventional techniques requires ongoing assessment.

Child↗
PubMed2004

Creation and characterization of a mouse model of mandibular distraction osteogenesis.

While the histological and ultrastructural changes associated with distraction osteogenesis have been extensively characterized using various animal models, the molecular mechanisms governing this technique remain poorly understood. In the current study, for the first time, we describe a mouse mandibular distraction osteogenesis model. Development of this model will allow assessment of factors involved in normal vs. abnormal healing (especially in non-unions) of craniofacial skeletal elements. Complete osteotomies were created on the right hemimandibles of 51 adult male CD-1 mice and customized distraction devices attached. Thirty-three animals underwent gradual distraction (5 days latency, distraction at 0.2 mm BID x 8 days, 28 days consolidation), while the remaining 18 mice underwent acute lengthening (immediate distraction to 3.2 mm) at the time of surgery. Mandibles were harvested at time points corresponding to the latent (POD 5), distraction (POD 9, 13), and consolidation (POD 28, 41) periods and processed for histological or quantitative real-time RT-PCR analysis. Specimens from each group were processed for microCT analysis. Histological and radiological data demonstrated that all mandibles undergoing gradual distraction achieved complete bony union by the end of consolidation, while those undergoing acute lengthening formed a fibrous non-union. Quantitative real-time RT-PCR demonstrated upregulation of mRNA for VEGF, FGF-2, collagen I, and osteopontin during gradual distraction but not during acute lengthening. These data validate our novel mouse mandibular distraction model and demonstrate its utility in elucidating the molecular mechanisms regulating bone formation during distraction osteogenesis as compared to those that are expressed during the formation of fibrous non-unions.

Animals↗
PubMed1999

Evaluation of the treatment for micromandibular deformity by distraction osteogenesis with submerged intraoral device.

OBJECTIVE: To evaluate the results of distraction osteogenesis for correcting the micromandible with an intraoral device. MATERIALS AND METHODS: Eight cases of micromandible resulting from temporomandibular joint (TMJ) ankylosis and first and second branchial arch syndrome received treatment by distraction osteogenesis. Subjects included 5 females and 3 males, ranging in age from 10 to 43 years (avg 20.25). Five micromandibles were associated with obvious mandibular asymmetry. An osteotomy was performed on bilateral mandibular bodies by intraoral approach. Elongation was started on the 5th or 6th day postoperation at a rate of 0.8 to 1 mm per day. The distractors were removed after a consolidation period from 71 to 139 days. RESULTS: The distractions were fulfilled with a range of 8.5 to 24.4 mm. Pain appeared in osteotomy region when the 1 mm distraction was carried out once a day and disappeared when it was divided into twice a day. Mandibular lengthening was successful. Micromandible and facial asymmetries were corrected satisfactorily. The follow-up period ranged from a minimum of 1 month to a maximum of 10 months. There was no recurrence. One case of soft tissue infection and one case of lower lip numbness were reported. There were no cases of infection or other disturbance of wound healing or pseudarthrosis. CONCLUSIONS: Because of its advantage in little injury, avoiding bone grafting, and few complications, intraoral distraction osteogenesis is a valuable approach to correct mandibular agenesis. However, in the management of mandibular deformities, distraction osteogenesis achieves better results when combined with other orthognathic operations. How to control the direction of distraction is a problem that needs further study.

Adolescent↗
PubMed2002

Mandibular functional reconstruction using internal distraction osteogenesis.

OBJECTIVE: To study the potential and advantages of internal distraction osteogenesis in mandibular functional reconstruction. METHODS: Three types of mandibular distractors were used in eight patients with various mandibular defects due to tumor or cyst resection. The average age of the patients was 31.5 years old (ages ranged from 8 to 54 years). For two patients with ramus defects, specially designed distractors were used to restore the normal ramus height. In two other patients, specially designed trifocal distractors were used. In three patients, vertical distractors were used. RESULTS: All the mandibles were successfully reconstructed in accordance with the direction and distance designed before operation except in one patient. In that patient the distal 23 mm defect failed to be corrected because of loosening of transport block fixation screws. CONCLUSIONS: Mandibular defects can be successfully corrected using internal distraction osteogenesis. Performing mandibular reconstruction using distraction osteogenesis is best done at the time of tumor or cyst resection.

Adult↗
PubMed2005

Multidirectional distraction osteogenesis for Crouzon syndrome: technical note.

This report describes multidirectional distraction osteogenesis in a patient with Crouzon syndrome. A RED system and a Hyrax expansion screw were used for lateral expansion of the maxilla. Advancement distraction osteogenesis and a Dyna Form were used for widening distraction osteogenesis of the mandible. The devices were fixed after a quadrangular osteotomy and a bimaxillary midline osteotomy.

Adolescent↗
PubMed2006

Distraction osteogenesis of the hypoplastic midface using a rigid external distraction system: the results of a one- to six-year follow-up.

BACKGROUND: The purpose of this study was to evaluate the long-term stability of maxillary distraction osteogenesis by use of a rigid external distraction device, based on a 7-year experience. METHODS: Nine patients with severe cleft maxillary hypoplasia were treated between January of 1998 and August of 2003. Their ages at the time of surgery ranged from 13 to 19 years. Distraction was started at 5 days after a Le Fort I osteotomy at a rate of 1 mm per day for 10 to 15 days. All patients used the Rigid External Distraction I system. After distraction was completed, the device was left in place for another 5 to 6 weeks for bony consolidation. When this was completed, an orthodontic face mask was used with elastic traction for 5 to 6 weeks. The follow-up period ranged from 1 to 6 years. RESULTS: The mean distraction length was 13.6 mm immediately after distraction, 10.8 mm at 6 months after distraction, and 10.4 mm between the 1- and 6-year follow-up period, resulting in relapse rate of 23.0 percent. In three children with mixed dentition, the ANB angle ranged from 7.1 to 8.5 degrees immediately after distraction, from 2.8 to 4.0 degrees 6 months postoperatively, and from 0.4 to 1 degree 5 years postoperatively. Therefore, the growth rate of the distracted maxilla was lower than that of the mandible in those three children. CONCLUSION: The results suggest that greater anterior overcorrection of the hypoplastic maxilla is needed in the growing child than in adults to compensate for a partial relapse and growth deficit.

Adolescent↗
PubMed1999

Distraction osteogenesis in Silver Russell syndrome to expand the mandible.

Distraction osteogenesis is a method commonly used to activate bone regeneration in nonunions and osseous defects and for lengthening procedures of tubular bones. This technique involves the sectioning of a bone and the subsequent deliberate, controlled movement of the opposing sectioned edges to lengthen, widen, or reposition a bone, or all three. In this report, a patient with Silver Russell syndrome and severe mandibular hypoplasia was treated by means of distraction osteogenesis of the midsymphysis to widen the mandible in concert with sagittal-ramus osteotomies to lengthen the mandible. This treatment created significantly increased arch length in the mandible, which was necessary to facilitate the patient's orthodontic treatment. We believe this is the first reported case of distraction osteogenesis to widen the mandible with the use of a tooth-borne appliance.

Cephalometry↗
PubMed2005

[Segmental mandibular reconstruction by elasticity distraction osteogenesis associated with guided bone regeneration].

OBJECTIVE: To accelerate distraction osteogenesis by utilizing guided bone regeneration technique, and to improve the automatic process of canine segmental mandibular reconstruction by elasticity distraction osteogenesis using shape memory metal alloy distractor. METHODS: Adult hybrid canines were used. Osteotomy was performed to remove a bone segment of 2.5-4.0 cm in one side of the mandible. Mandibular fixation devices and shape memory metal alloy distractor were secured according to the principles of bi-focal distraction technique. A piece of ePTFE membrane was sutured to cover the buccal side of bone defect and osteotomy gap of transport disc, where the periosteum was peeled for exposing mandible in operation. Then the incisions were totally closed. The canines were sacrificed 3 months later to harvest the mandibles for morphological observation and measurement of bone density and intensity. RESULTS: The shape memory metal alloy distractor performed distraction osteogenesis automatically and reconstructed the mandibles with bone defect. A regenerated bone segment of 1.5-2.0 cm was formed in the compression region between transport disc and contralateral mandibular end. The new bone in both of distraction and compression regions had similar height and thickness with normal mandible. Moreover the new bone density and intensity were rather satisfied. CONCLUSIONS: Membrane guided bone regeneration can avoid bone synthesis commonly caused by cicatrization of soft tissue in the bone defect, and accelerate ossification and maturation of new generated bone.

Animals↗
PubMed2006

Intermittent loading improves results in mandibular alveolar distraction osteogenesis.

AIM: To evaluate clinical and morphological effects on distractive callus after application of an original protocol of bone stimulation. MATERIAL AND METHODS: Traditional or mechanically stimulated alveolar-distraction osteogenesis was studied on 16 highly selected subjects subdivided into two groups. Clinical, radiological, densitometric and histological (on biopsies) analyses were performed 6, 8 and 12 weeks after distraction was completed. RESULTS: In subjects undergoing stimulated alveolar-distraction osteogenesis, bone density was higher and at histology, bone with ordered structure was observed after 6 weeks. Moreover, bone trabeculae with oriented architecture and greater amounts of lamellar bone were observed after 8 and 12 weeks in the same subjects. DISCUSSION AND CONCLUSIONS: In conclusion, although osteogenic processes were similar in both groups, they were induced earlier and were better structured in subjects undergoing stimulated alveolar-distraction osteogenesis. These encouraging results can only be achieved and preserved by strict monitoring of distractive vectors.

Absorptiometry, Photon↗
PubMed2003

Physiologic weight-bearing increases new vessel formation during distraction osteogenesis: a micro-tomographic imaging study.

During distraction osteogenesis, large volumes of new bone are formed through the slow distraction of fracture callus. The newly formed bone is closely linked to angiogenesis and positively influenced by physiologic loading. In this study, a rat model was used to explore the correlation between these two observations. Unilateral femoral lengthenings were performed in 18 male Sprague-Dawley rats (400-500 g, age<6 months). Half of the animals were allowed to bear weight freely (WB) while the remaining animals were made non-weight-bearing via a through-knee amputation (NWB). After a seven-day latency period, femurs were lengthened 7 mm over 21 days. Animals were sacrificed at 7, 21, 35, and 49 days (0, 4.7, 7, and 7 mm of distraction) at which time lower extremity vessels were perfused with a 60% (w/v) barium sulfate suspension. High-resolution three-dimensional images of the vascular architecture were generated using a fan-beam micro-tomography machine by digitally separating the contrast-filled vessels from surrounding tissue. For two subvolumes, VOI(1), which included vessels in the medullary canal, cortex, and periosteum, and VOI(2), which included only vessels in the canal and cortex, the total tissue volume (TV), the volume of vessels (VV), and vessel diameter (VD) were determined. For the larger subvolume (VOI(1)), VV and vessel density (VV/TV) increased as a function of time (p<0.001) in WB animals. In NWB animals, VV increased significantly with time (p=0.029), while VV/TV did not (p=0.36). Increases in VV and VV/TV were significantly greater in WB animals than in NWB animals (p<0.01 and 0.05, respectively). VD was similar in both groups and did not change with time. Our data suggest that weight bearing stimulates new vessel formation during distraction osteogenesis.

Animals↗
PubMed2002

Minor complications arising in alveolar distraction osteogenesis.

PURPOSE: This study evaluates complications that arise during mandibular alveolar distraction osteogenesis and suggests treatments. METHODS: We monitored complications that arose during alveolar distraction osteogenesis in 5 patients who underwent a total of 7 distractions, in all cases using an intraosseous distractor (Lead System, Leibinger, Germany). We report our responses to each type of complication. RESULTS: All 7 distractions were followed by the placement of 2 implants. The restoration was ideal in 4 of the 7 cases and functional but not ideal in the remaining 3. In all 7 distractions, we observed complications, although many were minor complications readily avoided by the use of appropriate technique. The complications were, first, intraoperative complications, namely 1) fracture of the transport segment (1 of 7 cases; RESPONSE: appropriate preventative measures), 2) difficulties in finishing the osteotomy on the lingual side (7 of 7 cases; RESPONSE: use of fine chisels made from cement spatulas), and 3) excessive length of the threaded rod (1 of 7 cases; RESPONSE: cut the rod). Second, complications arose during distraction: 1) incorrect direction of distraction (2 of 7 cases; no corrective measures necessary in the present cases), 2) perforation of the mucosa by the transport segment (2 of 7 cases; response: smooth the crest of the segment with a bone rongeur), and 3) suture dehiscence (1 of 7 cases; no significant implications). Third, there were postdistraction complications, namely bone formation defects (4 of 7 cases; response: guided bone regeneration). CONCLUSIONS: A number of complications may arise during alveolar distraction osteogenesis. Most of these complications can be considered minor and are readily avoided or resolved by the use of appropriate procedures.

Dental Implantation, Endosseous↗
PubMed2004

Distraction Osteogenesis of the Craniofacial Skeleton.

LEARNING OBJECTIVES:: After studying this article, the participant should be able to: 1. Review the biomechanical principles and pertinent cellular and molecular biology of distraction osteogenesis of the craniofacial skeleton. 2. Describe the clinical indications and applications of distraction osteogenesis of the craniofacial skeleton. 3. Describe maxillary, mandibular, midface, and calvarial procedures in distraction osteogenesis. 4. Discuss the clinical outcomes and complications of distraction osteogenesis of the craniofacial skeleton.The year 2002 marked the end of the first decade in clinical distraction osteogenesis of the craniofacial skeleton. In this short period, its application has increased exponentially. More than 3000 cases have been performed according to a recent survey, and more than 700 articles have been written on this subject in the MEDLINE database since 1996. It is a powerful surgical tool and enables surgeons to achieve results not previously attainable. Despite all this, distraction osteogenesis is practiced by only a small number of plastic surgeons. This article reviews the biomechanical principles; the pertinent cellular and molecular biology; and the clinical indications, applications, controversies, and complications of distraction osteogenesis of the craniofacial skeleton.

Journal Article↗
PubMed2004

Distraction osteogenesis of the porcine mandible: histomorphometric evaluation of bone.

Distraction osteogenesis is a technique for skeletal lengthening that exploits the body's innate capacity for bone formation in response to tension forces on the repair callus. The authors developed a distraction osteogenesis model with a semiburied device in the Yucatan minipig mandible because of similarities between human and porcine mandibular anatomy, temporomandibular function, chewing patterns, and bone turnover rates. The purpose of this study was to measure histomorphometric bone fill after different latency periods, rates of distraction, and duration of neutral fixation in the minipig mandible. In addition, the relationship between histomorphometric bone fill and clinical stability was investigated. Mandibular osteotomies in 20 female Yucatan minipigs weighing 25 to 30 kg were distracted with modified semiburied distraction devices. Variables included 0-day or 4-day latency; 1-mm, 2-mm, or 4-mm daily distraction rates; gap size of 7 or 12 mm; and evaluation after neutral fixation for various lengths of time. Specimens were fixed in 2% paraformaldehyde, pH 7.4, before being embedded in methylmethacrylate. Sections were prepared from the region just below the inferior alveolar canal. The area of new bone formation within the gap was measured and expressed as a percentage of the total area of the distraction gap. Bone fill ranged from 0 to 100 percent. A pilot study with 7-mm advancements showed similar bone fill with 0-day or 4-day latency, but with poor reproducibility. Mandibles that were distracted to 12 mm at 1 mm per day exhibited nearly complete bone fill, either with 0-day latency (average, 93 percent) or 4-day latency (average, 100 percent). Mandibles that had been distracted for 3 days at 4 mm per day showed moderate osteogenesis and clinical stability with increasing time of neutral fixation. Bone fill was significantly correlated with clinical stability (Spearman r = 0.801, p = 0.001). Histological examination showed exuberant periosteal osteogenesis in distracted mandibles, even in those that showed poor bone fill and clinical stability. Thus, the periosteum appears to be a major source of new bone formation. These results show that osteogenesis was nearly complete with 1 mm per day and 0-day or 4-day latency. These results are consistent with the authors' previously reported clinical and radiographic observations that a latency period is not necessary for successful healing of the mandibular distraction osteogenesis wound.

Animals↗
PubMed1994

Evaluation of distraction osteogenesis by scanning electron microscopy.

A model of bifocal distraction osteogenesis in the canine model was used to assess and quantitate the mineral content of the newly forming bone within the canine mandible. A 2-cm defect was created in the body of the mandible, and after a posterior osteotomy, the transport disk was advanced at 0.25 mm per 8 hours for 21 days and then held in rigid fixation for an additional week. As a control for this study, three additional dogs underwent the same procedure with the exception that the transport disk was not advanced. Electron dispersive spectroscopy analysis was performed on the newly formed regenerate bone and compared with areas of existing cortical bone of both the transport disk and the mandible. In the control model, special note was made of the pericortical callus at the osteotomy site as well as of the regenerative bone that filled the 2-cm defect in the body of the mandible. Calcium/phosphorous ratios were used to assess the composition of the mineralized regions of the mandible. The regenerate bone that filled the defect and the mineralized callus surrounding the site of osteoclasis in the control mandible were significantly different in composition when compared with the regenerate bone that formed during distraction osteogenesis. This suggests that distraction osteogenesis may effect an initial matrix production that is more similar in composition to the mature cortical bone from which it was derived than does periosteal regeneration and filling of an osseous defect.

Animals↗
PubMed2002

Overview of the radiology, histology, and bone morphogenetic protein expression during distraction osteogenesis of the mandible.

INTRODUCTION: Distraction osteogenesis (DO) is a form of in vivo tissue engineering during which an osteotomy and controlled distraction are used to lengthen bone. The molecular signals that govern distraction-induced bone formation have not been fully elucidated. Specifically, the role of bone morphogenetic proteins (BMPs) in DO of the mandible remains unclear. OBJECTIVE: To characterize the radiologic and histologic evolution of newly formed bone during DO of the mandible and to relate these changes to the expression of BMPs. METHODS: Fourteen skeletally mature male rabbits were used. A distractor device was surgically applied to one side of the mandible following osteotomy. After 1 week (latency period), distraction was started at a rate of 0.25 mm every 12 hours for 3 weeks (distraction period) and was followed by a 3-week consolidation period. Two animals were sacrificed each week after surgery (weeks 1 to 7). The mandible was resected and the new bone assessed by radiography and histology. The expression of BMPs was also analyzed using immunohistochemistry. RESULTS: There was radiographic and histologic evidence of bone formation during the distraction period. By week 6, there was mature woven bone within the distraction zone. Bone morphogenetic proteins 2 and 4 were strongly expressed in osteoblasts during distraction and in chondrocytes during consolidation. The expression of BMP-7 was relatively minor. CONCLUSION: The temporal and spatial pattern of BMP expression suggests that these proteins are important mediators of mandibular DO. Understanding the expression of BMPs may facilitate the use of recombinant proteins to enhance the rate and quality of bone generation during craniofacial DO.

Animals↗
PubMed2001

Remodeling of the temporomandibular joint following mandibular distraction osteogenesis in the transverse dimension.

Transverse mandibular distraction osteogenesis involves moving the osteotomized segments of the mandible in either a varus or valgus direction. This maneuver allows for widening of the bigonial distance or for a lateral shift of an asymmetric mandibular midline. During this process, a significant amount of torque is placed on the mandibular condyles, because they act as the pivot point for the mandibular translation. Although standard linear distraction osteogenesis induces transient, reversible changes in the temporomandibular joint, it is not known what effect the varus and valgus stresses of transverse distraction have on the temporomandibular joint. We therefore designed a study to document the temporomandibular joint changes following various degrees of transverse distraction. Bilateral transverse mandibular distraction was performed on 10 adult, female mongrel dogs using an external, multiplanar mandibular distraction device. The distraction protocol was as follows: (1) complete osteotomy at the angle of the mandible, (2) 5-day latency period, (3) distraction rate of 1 mm/day, (4) rhythm of one turn per day, (5) linear activation 16 to 30 mm bilaterally, and (6) 8-week consolidation period. A variety of varus and valgus distraction vectors were applied to the mandible only after 10 mm of initial linear distraction had been achieved. Posteroanterior and lateral cephalograms were performed throughout the entire process. Pre-distraction and post-consolidation computed tomographic scans were also performed. Changes in mandibular conformation, axis of rotation, temporomandibular joint structure, and glenoid fossa changes were directly assessed by evaluating the postmortem craniofacial skeleton. The findings were compared with those of normal, age-matched mongrel dog skulls. Significant remodeling changes were observed in the temporomandibular joints of all animals involved in the study. The mandibular condyles demonstrated varying degrees of flattening and erosion at all contact points with the craniofacial skeleton. In some cases, the condyle became part of the distraction regenerate process and was hypertrophied in all dimensions. The condyles were frequently displaced out of the glenoid fossa, particularly on the side in the direction of varus distraction. When the latter occurred, a new fossa was created on the undersurface of the zygomatic arch. Varying degrees of mandibular rotation in the sagittal plane were also observed, which led to abnormal torquing of the condyles in the coronal plane, depending on whether the axis of rotation occurred primarily around the condyle or around the distraction regenerate zone.In conclusion, transverse mandibular distraction is an effective means of producing a varus or valgus shift in the gonion relative to the midsagittal plane. However, unlike linear or angular mandibular distraction, transverse distraction has a multitude of nontransient effects on the temporomandibular joint. Therefore it must be emphasized that in clinical practice, transverse distraction should be used cautiously. One must also be aware that such a maneuver in distraction can have negative effects on the temporomandibular joint.

Animals↗
PubMed1997

Sustained proliferation accompanies distraction osteogenesis in the rat.

These studies were conducted to compare the local cellular proliferation patterns in the rat tibia during distraction osteogenesis with those during nondistracted fracture healing. Bone specimens from distraction osteogenesis and nondistracted fracture groups were analyzed 2, 10, and 20 days after surgery. Proliferation was determined by metabolic labeling with [3H]thymidine and by immunocytochemistry with an antibody to proliferating cell nuclear antigen. Videomicroscopy was used to count the cells staining positively within specified regions. The number of cells incorporating [3H]thymidine was positively correlated (r2 = 0.78) with the number of proliferating cell nuclear antigen positive cells on alternating serial slides. At day 2, the latter cells were largely confined to the bone marrow and periosteum in both groups, and the cell numbers per mm2 were also equivalent. At days 10 and 20, the proliferating cell nuclear antigen positive cells predominated in both the proximal and distal primary matrix front zones in the distraction osteogenesis group. In contrast, the proliferating cell nuclear antigen positive cells in the nondistracted fracture group were scattered throughout the healing area. Significantly more of these cells were in the primary matrix front zones than in any location within the nondistracted fracture-healing area. The number of these cells in the bone marrow adjacent to the surgical area declined from day 2 to day 10 in both groups. The results suggest that (a) proliferating cell nuclear antigen immunostaining is a reliable indicator of cycling cells; (b) by day 10, distraction osteogenesis is characterized by a zone-specific pattern of proliferating cells; and (c) distraction osteogenesis prolongs the stimulation of proliferation within the gap after fracture.

Animals↗
PubMed2003

Fourth brachymetatarsia treated with distraction osteogenesis.

BACKGROUND: This study investigated metatarsal lengthening by distraction osteogenesis for fourth brachymetatarsia in 22 metatarsals (16 patients). METHODS: From May 1997 to May 2000, lengthening was performed with a monoexternal fixator, and distraction was started at a rate of 0.5 mm per day after a latency period of approximately 7-10 days. RESULTS: The average gain in length was 16.5 mm (range, 13-21 mm), equivalent to an increase of 39% (range, 28-51%), and the average healing index was 72.9 days/cm (range, 51.7-95.7 days/cm). The American Orthopaedic Foot and Ankle Society (AOFAS) average score for lesser toe was 86.3 (range, 47-100). The most common residual complication was subluxation of metatarsophalangeal (MTP) joint in five cases, with partial or total stiffness of the MTP joint. These complications happened in the group of metatarsals excessively lengthened more than 40% and made the AOFAS score poorer. The other complications were three cases of angular deformity in the lengthened bone, and two cases of pin-tract infection. CONCLUSION: Although distraction osteogenesis is an effective method to address fourth brachymetatarsia, stiffness or subluxation of the MTP joint was not uncommon. To avoid complications that can happen as a result of excessive lengthening, careful preoperative radiographic measurement to calculate the optimal amount of lengthening may help us to avoid overlengthening and the complications that accompany it.

Adolescent↗