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Indication for and surgical outcomes of the distraction method in various types of craniosynostosis. Advantages, disadvantages, and current concepts for surgical strategy in the treatment of craniosynostosis.

BACKGROUND: Various surgical techniques for the treatment of craniosynostosis using distraction devices have been described over the last few years and we have applied these procedures in seven patients with varying types of craniosynostosis. The aim of this report is to clarify the advantages and disadvantages of these surgical methods and to discuss current concepts for the surgical strategy in the treatment of craniosynostosis. MATERIAL AND METHODS: From January 2001 to March 2003, 25 patients with craniosynostosis were examined. Among them, 7 patients, 5 with Apert syndrome, 1 with Crouzon disease, and 1 with multiple-synostosis, underwent surgical treatment using the distraction method with internal distraction devices, according to our treatment strategy for craniosynostosis. All patients underwent preoperative and postoperative evaluations, which included the patient's neurological state, developmental quotient (DQ), and three-dimensional CT (3D-CT). RESULTS: The timing of the procedures undertaken was between the ages of 1 year 5 months and 12 years 6 months (mean age 4 years 11 months). Five patients had received previous treatment and this procedure was used as a secondary operation. Postoperative distraction distances varied from 7 to 20.5 mm (mean distraction distance: 14 mm). Satisfactory cranial volume expansion and aesthetically pleasing morphological states were achieved in all cases. Regarding complications, one patient required re-operation because of dislocation of the device and skin erosion caused by infection around the penetrated wound. Finally, in a second patient a distortion of the device occurred, but no re-operation was needed. CONCLUSION: The advantage of the distraction method is its applicability for Toddler or Elder Children Calvarial Reconstruction to correct cosmetic and functional problems. One disadvantage is the difficulty in using it for Infantile Calvarial Normalization because of thin calvarial bones and the necessity for re-operation to remove the device, which may result in it becoming a "fixation procedure," essentially contraindicated for the fast-developing brain and calvarias. However, the efficacy of this procedure is that the many advantages outweigh the disadvantages as sufficient calvarial expansion and good results using the distraction method, especially in toddler and elder children age groups, can be achieved.

Age Factors↗

Biomechanical evaluation of the pins of a mandibular external distractor.

PURPOSE: Our goal was to establish whether the pins of an external distractor were capable of overcoming tissue resistance to distraction. MATERIALS AND METHODS: The study was carried out in 2 parts. The first part of the study determined the bending rigidity of the distractors pins. To accomplish this, the distractor was installed on the mandible of a stereolithographic model using 4 regular 2.0-mm steel pins. An osteotomy was not performed. The distractor was activated using a torque gauge, and the bending rigidity of the pins was recorded. The second part of the study determined the tissue resistance to mandibular distraction using fresh cadavers. Six cadavers were divided into 2 groups to determine tissue resistance to angular and linear distraction, respectively. The devices used to measure tissue resistance were a modified external multiplanar distractor and a torque gauge. RESULTS: In the anteroposterior direction, the tissue resistance to linear distraction clearly exceeded the bending rigidity of the pins for the first 7.5 mm of activation. After this, the opposite was true. In the vertical direction, the tissue resistance clearly exceeded the bending rigidity of the pins for the first 8.0 mm of activation. After this, the opposite was true. For the first 15.0 degrees of angular distraction in the sagittal plane, the tissue resistance was almost identical to the bending rigidity of the pins. After this, the tissue resistance significantly exceeded the bending rigidity of the pins. For the first 7.0 degrees of angular distraction in the transverse plane, the tissue resistance was marginally greater than the bending rigidity of the pins. After this, the bending rigidity of the pins increased significantly. CONCLUSION: The 2.0-mm steel pins used in most external multiplanar distractors are not capable of overcoming the tissue resistance to linear or angular distraction.

Biomechanical Phenomena↗

Osteogenic alveolar distraction: a review of the literature.

OBJECTIVE: Alveolar distraction is a relatively novel procedure by which alveolar bone and underlying mucosa are regenerated. The low predictability of other vertical or horizontal bone regeneration methods has increased interest in this promising technique. This article was designed to review published clinical and experimental results on alveolar distraction, including basic research in other disciplines (maxillofacial and orthopedic distraction) related to or with influence on alveolar distraction. STUDY DESIGN: A review of the international literature was performed to summarize results of clinical and experimental studies on alveolar distraction and on distraction at other anatomical sites that contribute important findings on tissue biology, molecular mechanisms, and other factors that influence and participate in the alveolar distraction process. RESULTS: Research into alveolar distraction has addressed the latency phase, distraction phase, and consolidation phase, yielding highly variable results. Little experimental research has been carried out on this procedure, and most publications are clinical studies with a short follow-up period. Published studies have reported a high rate of complications, attributable to our current lack of understanding of the process. CONCLUSIONS: Definitive conclusions on alveolar distraction are hampered by the lack of clinical and experimental studies to date. Greater knowledge of the factors that influence the distraction process will lead to a more predictable and efficacious distraction technique and a better distractor design.

Alveolar Ridge Augmentation↗

Callus distraction in the hand skeleton.

From 1992 to 1996, 27 patients with traumatic amputations or malformations underwent lengthening of thumb and fingers. A total of 36 procedures were carried out. In several cases, deepening of the web space or bone transplantations proved to be necessary to improve general function or to compensate for missing bone structure. Complications included pin-track infections, necrosis of bone, non-union and scarring. Overall the results indicate that distraction of the thumb and fingers is a feasible operative technique leading to a promising improvement of function.

External Fixators↗

Le Fort III midfacial distraction using an internal distraction device for syndromic craniosynostosis: device selection, problems, indications, and a proposal for use of a parallel bar for device-setting.

Le Fort III midfacial distraction using internal and external devices is a well-accepted procedure for the midfacial retrusion of craniosynostosis syndrome patients. The authors described 20 consecutive series of Le Fort III midfacial distraction using internal distraction devices. Two types of devices were utilized. One type was a zygoma-skull device (the anterior part of the device is attached to the zygoma, and the posterior part is attached to the skull), which was used in six cases. The other was a zygoma-zygoma device (the anterior and posterior parts of the device are attached to the osteotomized zygoma, respectively), which was used in 14 cases. Subject ages ranged 3-32 years. A 14-20-mm distraction length was obtained by 1 mm/day. Satisfactory distraction of the midface was obtained in 17/20 cases. In 3/6 cases in which a zygoma-skull device was used, an unsatisfactory result was obtained. In these three cases, a fracture of the zygomatico-maxillary suture was encountered, resulting in the Le Fort III portion being left behind. In all 14 cases in which a zygoma-zygoma device was used, a satisfactory result was obtained. During the distraction period, the connection of the distraction device was dislodged, resulting in re-connection in three cases. Slight asymmetry was noticed in two cases without any need for management. In order to obtain parallel setting of the bilateral distraction devices, a newly developed parallel bar was used and demonstrated to be effective.

Acrocephalosyndactylia↗

Trapeziectomy.

Primary osteoarthritis of the carpometacarpal joint of the thumb is common, especially in women aged 60 or older. Patients usually present with activity-related pain at the thumb base. First treatment may include activity modification, pain relieving medications, splinting, and possibly corticosteroid injections. When these measures fail to pre-serve or restore the patient's quality of life, surgical intervention may be appropriate. Many surgical alternatives are described for the treatment of thumb carpometacarpal joint arthritis, and most begin with at least partial trapeziectomy. Hematoma-distraction arthroplasty results in improved outcomes as compared with historical results following trapeziectomy alone. Temporary distraction allows the body's healing response to fill in the trapezial void with scar tissue, obviating the need for ligament reconstruction or tissue interposition.

Arthritis↗

Palatal approach for maxillary alveolar distraction.

PURPOSE: The purpose of this report was to describe a surgical technique for performing alveolar distraction in the upper jaw via a palatal approach. PATIENTS AND METHODS: To illustrate this technique we report 2 clinical cases in which palatal-approach alveolar distraction was used to rectify insufficient alveolar rim height. The first case involves a 50-year-old man with atrophy of the alveolar rim in the posterior upper jaw. From the palatal side, a transport segment pedicled to the vestibular mucosa was cut, and 2 Lead System distractors (Leibinger, Kalamazoo, MI) were placed. The second case involves a 23-year-old woman with a bone defect in the alveolar rim in the premaxillary sector of the upper jaw. Again, from the palatal side, a transport segment pedicled to the vestibular mucosa was cut, and a single Lead System distractor was placed. RESULTS: In both cases the height of the alveolar rim was successfully increased by 8 mm, allowing placement of three 12-mm implants in case 1, and two 12-mm implants in case 2. CONCLUSIONS: We recommend a palatal approach and intraosseous distractors for alveolar distraction in the upper jaw.

Adult↗

High frequency distraction improves tissue adaptation during leg lengthening in humans.

The present study investigates the effect of distraction frequency on the development of tensile force in the tissues during lengthening. Two patients with bilateral Ilizarov leg lengthening underwent distraction with high frequency in one leg and low frequency in the other. The clinical situation represented a unique model for investigating the effect of distraction frequency, as each individual served as its own control. Both patients had double level lengthening. Distraction frequency at the proximal lengthening zone was 0.25 mm x 4 in the first leg and 1/1440 mm once every minute in the other. Total diurnal distraction at the proximal metaphysis was 1 mm in both legs. In addition, a distal metaphyseal distraction of 0.25 mm x 3 daily was performed on each leg. The tissue's mechanical response was monitored by measuring the tensile force at the proximal osteotomy. Both patients experienced a significant lower level of force during the high frequency lengthening. The lower level of force was concluded to be due to improved soft tissue adaptation, rather than reduced bone regeneration. Accordingly, high distraction frequency was considered favourable to low frequency, and is recommended in large lengthenings where high force levels are expected.

Adaptation, Physiological↗

Gonial angle changes after bilateral unidirectional mandibular distraction in sheep.

It was the aim of this study to investigate radiologically the distraction site in the gonial angle area after three different protocols of unidirectional mandibular distraction in sheep. Bilateral mandibular distraction was performed in nine sheep, and one other sheep served as a sham-operated control. In the nine experimental sheep, three different distraction protocols were used. In three sheep, an oblique corticotomy line was applied and the distractors were positioned perpendicular to the corticotomy line. In three other sheep, a horizontal corticotomy line was applied and the distractors were also positioned perpendicular to this corticotomy line. In the remaining three sheep, again, a horizontal corticotomy was performed, but with an angular positioning of the distractors relative to this corticotomy line. Distraction of 20 mm was performed over 20 days at a rate of 1 mm per day. After 3 weeks of retention the sheep were sacrificed, the mandibles were dissected and hemisectioned, and standardized hemimandibular contact radiographs were made of the specimens. The distracted gaps were traced from the radiograph and the gonial angle was measured. The displacements of the distracted parts were measured, the gonial angles were determined, and the values were compared with four additional control non-distracted sheep mandibles. The results show that there was a very large variability in the distracted gaps as well as in the gonial angle changes after distraction, and it was not possible to recognize any of the three different distraction protocols radiographically after distraction. Although performed under standardized conditions it is difficult to reproduce intended mandibular corticotomy lines in sheep.

Animals↗

Effect of rhythm and level of distraction on muscle structure: an animal study.

To determine the optimal rhythm of distraction and level of osteotomy for maximal muscle preservation during limb lengthening, histologic and ultrastructural analysis of the peroneus tertius muscle was performed in 46 goats. Thirty-nine animals with 20% or 30% tibial lengthening at the rate of 0.75 mm per day at each osteotomy level were divided in two groups. The first group included 15 animals undergoing tibial middiaphyseal lengthening with automated distractor producing one (n = 5), four (n = 5), or 720 (n = 5) increments per day. The second group included 24 animals in which lengthening was performed at the proximal (n = 4), middle (n = 6), distal (n = 6), or double (n = 8) level of the tibia with distraction rhythm of three times per day. The remaining seven animals served as controls. Histomorphologic features of the lengthened muscles were characterized by a polymorphous appearance with foci of necrosis, atrophy, and sclerosis scattered among apparently normal muscle fibers. The intensity and dispersion of degenerative changes were in direct proportion to the amount of lengthening but in reverse proportion to the frequency of distraction. Tibial lengthening at the diaphysis caused intense fibroblast proliferation and remarkable muscle sclerosis, whereas metaphyseal distraction was associated with a predominance of muscle tissue regeneration over atrophy and sclerosis. Bifocal lengthening and a more fractionated rhythm of distraction were associated with enhanced preservation of existing muscle fibers and greater regenerative activity of the muscle.

Animals↗

Single-level fixation of flexion distraction injuries.

Flexion distraction injuries of the thoracic and lumbar spine can be stabilized with a short construct spanning one motion segment. This surgical technique has not been well accepted because of the paucity of published outcomes of patients treated in this manner. The current study is a cohort of patients who underwent a standardized posterior open reduction and single-level fixation for this injury pattern. Independent observation prospectively followed the cohort for a minimum of 20 months with functional and radiologic outcomes determined. A significant (p < 0.0001) correction of deformity was achieved, from a mean preoperative kyphosis of 10.1 degrees to a mean postoperative lordosis of 0.9 degrees. No loss of correction occurred. The mean Oswestry score was 11.5, with 88% of patients having minimal disability. This prospective study demonstrates the efficacy of posterior open reduction and single-level fixation of flexion distraction injuries.

Adolescent↗

Biomechanical evaluation of calcaneocuboid distraction arthrodesis: a cadaver study of two different fixation methods.

Calcaneocuboid distraction arthrodesis can be used to treat stage 2 posterior tibial tendon dysfunction. Nonunion, graft resorption, and implant failure have been reported after this procedure. This study compared two of the most commonly used methods for fixation of calcaneocuboid distraction arthrodesis. Twelve pairs of cadaver feet underwent simulated calcaneocuboid distraction arthrodesis. One specimen in each pair was fixed with two crossed 3.5 mm cortical lag screws. The contralateral specimen was fixed with a cervical H-plate. The calcaneus was fixed and a load was applied to the plantar aspect of the cuboid at a rate of 5 mm/minute until joint separation of 3 mm or fracture occurred. The average applied load to failure at 1.0 mm of joint separation was 30.5 +/- 11.6 N for the crossed screws and 77.7 +/- 36.4 N for the cervical H-plate (p = 0.001). The average stiffness at 1.0 mm of joint separation was 27.5 +/- 10.9 N/mm for the crossed screws and 43 +/- 21.2 N/mm for the cervical H-plate (p = 0.036). The higher stiffness and load to failure may account for the decreased nonunion rate noted anecdotally by some surgeons with H-plate fixation over crossed screw fixation for calcaneocuboid distraction arthrodesis.

Aged↗

Cranial remodeling to treat craniosynostosis by gradual distraction using a new device.

OBJECT: The authors describe their experience in remodeling the shape of the cranium in children with craniosynostosis by using gradual distraction. In half of the cases, a new distraction device developed by the authors was used. METHODS: Twenty children with craniosynostosis underwent frontoorbital advancement and cranial remodeling assisted by gradual distraction. There were five children with brachycephaly, two with oxycephaly, five with scaphocephaly, two with plagiocephaly, one with combined scaphocephaly and plagiocephaly, and five with trigonocephaly. Four cases were syndromic and 16 were nonsyndromic. The patients ranged in age from 3 to 50 months (mean 14.5 months) at the first surgery. Simulated surgery was first performed on a three-dimensional solid model made of polyurethane, which accurately represented cranial flexibility, to determine the most favorable osteotomy line. Distraction was initiated 1 week postoperatively. The speed and extent of advancement (maximum extension 45 mm) were predetermined on the basis of previously reported criteria and the results of simulated surgery. Postoperatively, the cranial configuration was favorable in all cases. Spontaneous remodeling of irregularities and/or gaps apparent after distraction was found to occur 2 to 5 months after removal of the distraction devices, especially in patients with trigonocephaly or scaphocephaly. No major perioperative complication was observed in any patient. There were minor complications in six of the first 10 cases, including exposure of the device, shaft slippage, and fluid discharge. A new device was developed and used on the last 10 patients treated; it successfully eliminated device exposure and shaft slippage. A 3-year follow-up review confirmed that there was no relapse of advanced bones. CONCLUSIONS: Highly satisfactory results were achieved in cases of both syndromic and nonsyndromic craniosynostosis when gradual distraction was performed.

Bone Remodeling↗

Lengthening in free vascularized fibular graft.

A free vascularized fibular bone transfer was successfully performed in a 1-year-old child to reconstruct the loss of the right humeral shaft following neonatal osteomyelitis. Subsequent growth of the child resulted in gross arm length discrepancy, with associated functional deficits. Callostatic distraction-lengthening of the vascularized fibular graft was carried out to compensate for this limb length discrepancy by using an Ilizarov external fixator. Lengthening of 6 cm over a 3-month period, representing a 75% increase in the original length of the transplanted fibula, was achieved. Active bone regeneration, good corticalization and endosteal medullary cavity formation was observed in the lengthened fibula. The combined modalities of vascularized bone transfer and Ilizarov callostatic distraction-lengthening offer a solution for reconstruction for large segmental bone loss associated with growth arrest of the epiphyseal plates in children.

Female↗

Iliofemoral distraction and hip reconstruction for the sequelae of a septic dislocated hip with chronic femoral osteomyelitis.

We describe a technique of 'cross-hip distraction' to reduce a dislocated hip with subsequent reconstruction of the joint for septic arthritis with extensive femoral osteomyelitis. A 27-year-old woman presented with a dislocated, collapsed femoral head and chronic osteomyelitis of the femur. Examination revealed a leg-length discrepancy of 7 cm and an irritable hip. A staged technique was used with primary clearance of osteomyelitis and secondary reconstruction of the hip. A cross-hip monolateral external fixator was used to establish normal anatomy followed by an arthroplasty. A good functional outcome was achieved. The use of cross-hip distraction avoids soft-tissue and nerve damage and achieved improved abductor function before arthroplasty.

Adult↗

Trans-sinusoidal maxillary distraction in three cleft patients.

The trans-sinusoidal maxillary distractor (TS-MD) was used to achieve maxillary advancement in three patients with repaired cleft lip and palate. After preoperative computer-aided planning of the distraction vectors, each TS-MD was bent on a stereolithographic model of the maxilla of the patient. The devices were intraoperatively positioned using a methyl-methacrylate template. After standard Le Fort I osteotomy the devices were intraorally activated. After distraction the devices remained in situ for 3 months as rigid internal fixation of the maxilla. All patients were successfully distracted according to protocol. Maxillary advancement was 12, 8 and 11 mm. In two patients, additional maxillary widening of 6 and 8 mm was achieved by choosing divergent distraction vectors. After distraction a clockwise rotation of the maxilla was observed in two patients. There was no relapse during the 3 months of consolidation and 12-month follow-up. The TS-MD allows not only distraction but also rigid internal fixation after distraction. It was easy to apply but difficult to remove. Owing to preoperative 3D planning of the distraction vectors, the results were predictable, but clockwise rotation of the maxilla during distraction should be considered in planning. The distractor did not interfere with function or social activities during distraction and retention periods. After removal it left no extraoral scars.

Adolescent↗

Evaluation of a semiburied, fixed-trajectory, curvilinear, distraction device in an animal model.

PURPOSE: This study evaluated a new small, buried distractor, capable of curvilinear movement while following a fixed trajectory. The geometrical basis for such devices and the 3-dimensional treatment planning system required to make buried distractors practical are discussed. MATERIALS AND METHODS: A curved rack and worm-gear device, based on the design of a hose clamp, was constructed to produce a curved distraction path, and this distractor was tested in 2 minipigs using a protocol with zero latency and 1 mm/d x 7 days of distraction. Serial standardized lateral cephalograms were used to verify distractor function and path. RESULTS: Curvilinear distraction was documented by clinical examination and serial cephalometric analysis in the 2 minipigs. Observed angulation of the margins of the wedge-shaped distraction gap conformed to the calculated angulation based on the fixed radius of curvature of the distractor. CONCLUSION: Distraction along a curved trajectory using a small, semiburied, curvilinear device of novel design is feasible in the minipig mandible.

Animals↗

Cranial distraction for plagiocephaly: quantitative morphologic analyses of cranium using three-dimensional computed tomography and a life-size model.

The aim of this study was to analyze the morphologic changes of the craniofacial skeleton in synostotic plagiocephaly after cranial distraction. Preoperative and postoperative computed tomography scans were taken, and three-dimensional reconstruction was then performed. Three measurements were obtained: intracranial volume, volume of the middle cranial fossa, and length of the zygomatic arch. Intracranial volume reached values that were normal for a 2-year-old child postoperatively, and the discrepancy between left and right half volumes decreased over time. The discrepancy of the volume of the middle cranial fossa also decreased after surgery, and the asymmetry of the zygomatic arch improved significantly. Based on these objective findings, the authors believe that cranial distraction could favorably affect craniofacial dysmorphology of synostotic frontal plagiocephaly.

Brain↗