Adaptation of the cranium to spring cranioplasty forces.

BACKGROUND: During spring-assisted cranioplasty, the spring transmits forces through adjacent cranium. We have previously demonstrated that the ectocranial-endocranial thickness of cranial sutures increases significantly over time in the presence of continuous spring forces. We wished to investigate if cranial bone showed similar adaptational responses. METHODS: New Zealand white rabbits were randomized into a treatment group [a spring was placed across a posterior frontal suture (PFS) suturectomy and a control group (PFS suturectomy)]. Animals (n = 6) were euthanized from each group at 4, 7, and 10 weeks, respectively. A sham group (n = 6) was euthanized at 10 weeks. Frontal bone thickness was recorded at five reproducible anatomical points on the frontal bone. Histological analysis of the bone architecture was performed. RESULTS: Frontal bone thickness was significantly greater than controls at all five sites at weeks 7 and 10. There were multiple significant differences between the 4-, 7-, and 10-week groups with each site progressively thickening over time. Histological analysis revealed a uniform increase in thickness of the endocranial and ectocranial cortical bone in the treatment groups. CONCLUSIONS: Cranial bone adapts to the presence of continuous spring cranioplasty forces by progressively thickening over time. This property is beneficial in craniosynostosis cases with very thin and poor quality bone and may partly explain the observed lack of spring erosion through bone.

Spring expansion is influenced by cranial biomechanics.

INTRODUCTION: Spring cranioplasty is used in selected cases of craniosynostosis. A rabbit model was used to determine (1) if cranial biomechanics modify the expected rate of spring expansion, (2) the residual spring force in situ after cranial expansion, and (3) if the spring weakens during clinical use. MATERIALS AND METHODS: Twenty-seven New Zealand white rabbits were divided into 3 groups: the treatment group that underwent posterior frontal suturectomy and spring expansion (n = 15) and the control (n = 6) and sham groups (n = 6) that underwent suturectomy and incision only, respectively. Cephalography measured cranial expansion for 7 weeks. Spring force-deflection curves were measured in a dynamometer before and after use. RESULTS: Significant cranial expansion was observed for 8 hours (15% of the total expansion). The rate of expansion decreased significantly between 48 and 96 hours followed by a second period of rapid expansion from 96 hours to 7 days (P = 0.001). Approximately 80% of expansion was achieved by 2 weeks and 90% by 3 weeks. Initial spring force was 9.4 N (range, 7.2-10.7). Once the spring had achieved 90% of its eventual expansion, it retained 40% of its original force. At the completion of cranial expansion, the residual spring force was 2.6 N (range, 1.4-4.0) or 28% of the original spring force. All springs maintained identical load-compression curves after use. CONCLUSIONS: The craniofacial structures are mechanically complex and modify the uniform expansion curve expected as the spring force decays. Significant force is maintained within the spring at the completion of cranial expansion. This may have implications for possible relapse if the springs are removed early.

Frontobasal suture distraction corrects hypotelorism in metopic synostosis.

BACKGROUND: Spring-assisted cranioplasty has been demonstrated to correct hypotelorism associated with metopic synostosis. In addition, the fronto-orbital axis rotates toward a more normal orientation. We postulated that spring-induced shear forces and subsequent displacement across the frontobasal sutures are the primary initial mechanisms for change in cranio-orbital morphology. METHODS: Sixteen consecutive patients (32 orbits) with trigonocephaly operated on between 1999 and 2004 were studied retrospectively. After frontal remodeling, a spring was placed across the released metopic suture. Preoperative and 6-week postoperative cephalograms were used to measure the relative translation of the medial orbital wall from the midline at fixed vertical distances above and below the frontoethmoidal suture (FES). The vertical height of the spring above the frontonasal suture and the patient's age were analyzed with respect to the increase in bony interorbital distance (BIOD). RESULTS: There were significant increases in movement of the medial orbital wall above the FES at each measurement point (P < 0.001). There was no significant postoperative movement of the medial orbital wall below the FES at any measurement point. The relative movements above the suture suggest a degree of plastic deformation adjacent to the suture.There was no significant correlation between the age of patient or the height of the spring above the frontonasal suture and the increase in BIOD. CONCLUSION: Tensile spring forces are transmitted directly to the frontoethmoid suture. Most initial increases in BIOD and altered intraorbital morphology are due to distraction of cranial base sutures rather than plastic deformation.

Do expansile cranial springs erode through the cranium?

UNLABELLED: Expansile cranial springs are used in selected cases of craniosynostosis. The spring exerts moderate force against the relatively thin skull. We investigated whether the spring erodes through the bone and the clinical significance of any erosion relative to the cranial expansion achieved. METHODS: New Zealand white rabbits (n = 10) underwent sagittal suturectomy and spring insertion. Amalgam markers were placed perpendicular to the expected direction of suture erosion. A control group (n = 10) underwent suturectomy. Radiological evaluation was performed for 7 weeks to check for migration of the spring foot. RESULTS: The mean cranial thickness was 1.4 mm at the site of spring insertion. This compared with 1.8 mm in 7 children undergoing spring cranioplasty. The mean spring force was 9.4 N. In sagittal synostosis, the mean spring force used is 7 to 10 N.The cranial width increased 11.02 mm in the spring treatment group compared with 0.23 mm in the control group (P < 0.001). Spring erosion occurred in 4 (20%) of the 20 spring ends. Mean spring erosion for the treatment group was 0.18 mm. This was 3.2% of the mean increase in cranial width. The maximum percentage spring erosion versus cranial expansion in an individual rabbit was 14.17%. There was no statistical difference in cranial expansion between the rabbits in whom bone erosion did and did not occur. CONCLUSIONS: The degree of spring force required to effectively expand the cranium may cause bone erosion in some individuals. This degree of spring erosion was of minimal clinical significance in this animal model.

Sagittal synostosis: I. Preoperative morphology of the skull.

The aim of this study was to characterise the preoperative morphology of the skull in sagittal synostosis in an objective and quantified way. The shapes of the skulls of 105 patients with isolated premature synostosis of the sagittal suture (SS group) were studied and compared with those of a control group of 72 children with unilateral incomplete cleft lip (UICL). A standardised radiocephalometric technique was used to obtain the images. A modification of a method developed by Kreiborg was used to analyse the radiocephalograms, which included the digitisation of 88 landmarks in the calvaria, skull base, and orbit (42 in the lateral and 46 in the frontal projections), the production of plots of mean shape for each group, and the intergroup comparison of a series of 81 variables (linear distance between selected landmarks, and angles defined by groups of three landmarks). Data from a subgroup of 66 patients aged 5 to 8 months were further compared to age-matched normative data in terms of seven angular and linear calvarial, cranial base and orbital variables. In a comparative analysis of the mean lateral plots, the foreheads of the study group (SS) had a more pronounced anterior slope and were also more convex. The vertex area was located more anteriorly, and was less convex. The occipital curvature was more prominent. Analysis of the mean frontal plots revealed a lack in convexity and lateral projection of the upper parietal regions, as well as a lower location of the line of maximum skull width. Comparison of the mean values of an SS subgroup to age-matched normative data showed a longer (p<0.001) and narrower skull (p<0.001) and a greater interorbital distance (p<0.001). The cranial base angle, the sella to nasion, and sella to basion lengths did not differ significantly. Sagittal synostosis is characterised by an extensive deformity of the cranial vault, with an essentially normal cranial base. The widened interorbital distance is probably related to compensatory metopic hyperactivity.

Sagittal synostosis: II. Cranial morphology and growth after the modified pi-plasty.

The aim of this study was to characterise the postoperative cranial growth and morphology after a modified pi-plasty for sagittal synostosis. The shape of the skull of 82 patients with isolated premature synostosis of the sagittal suture (SS group) operated on with a modified pi-plasty was studied longitudinally. Forty-five children with unilateral incomplete cleft lip (UICL), evaluated longitudinally at the ages of 2.4 and 23.2 months were used as controls. A standardised radiocephalometric technique was used for image acquisition. The radiocephalograms were analysed using a modification of a method developed by Kreiborg, which included the digitisation of 89 landmarks of the calvaria, cranial base, and orbit (43 in the lateral and 46 in the frontal projections), the production of mean shape plots for each group, and the intergroup comparison of a series of 78 variables (linear distance between selected landmarks, and angles defined by groups of three landmarks). Paired and unpaired t tests were used to assess the differences between the variables studied. These were accepted as significant for values of p<0.01 and were presented as coloured segments or areas in the respective plots. In a comparative analysis with the mean UICL lateral plots, the mean preoperative lateral plots of the study group (SS) showed that the anterior slope of the forehead was more pronounced and it was also more convex. The vertex area was located more anteriorly and was less convex. The occipital curvature was more prominent. Comparison of the mean frontal plots showed a deficiency in convexity and lateral projection of the upper parietal regions, and the line of maximum skull width was lower. The postoperative mean lateral plots of the study group showed a correction of the exaggerated anterior inclination of the forehead and a reduction of the abnormal occipital convexity. However, there was little change in the vertex region and it remained flatter than in the control group. In the mean frontal plots, the increase in convexity and in the lateral projection of the upper parietal areas led to a shape that was similar to that of the UICL group. The mean (SD) cephalic index changed from 64.9% (1.8%) to 71.4% (3.5%) (p<0.001). The longitudinal comparison between the mean postoperative plots at 3 and 5 years of age showed that there had been little change in cranial shape. In conclusion, after a modified pi-plasty for sagittal synostosis, significant objective changes in cranial shape towards normality were produced. The postoperative profile cranial shape was improved except in the vertex area, which remained flatter than normal. In the frontal projection an almost normal shape was obtained. The postoperative cranial shape obtained at 3 years of age had remained stable at the age of 5 years.

Calvarial bone distraction with a contractile bioresorbable polymer.

The aim of the present study was to evaluate the possibility of mobilizing calvarial bone with a fully implantable and bioresorbable device. The animal model used was the New Zealand white rabbit (n = 12). An island bone flap attached to the dura mater was created in the parietal region and amalgam markers were placed in this bone flap and in the ipsilateral frontal bone. In one group of six rabbits (group 1), a specially processed contractile 70L/30D,L polylactic acid plate, 15 x 6 x 0.6 mm, was attached to the island flap by one extremity, and to the fixed ipsilateral frontal bone by the other. In group 2 (control), no plate was added. Bone marker movement was followed with serial radiography. In group 1, there was a progressive reduction in mean marker distance over the first 48 hours, and stability thereafter. In group 2 (control), mean marker distance remained stable until the second postoperative week, after which time there was a slight increase until the end of the experimental period. At 4 weeks, the mean marker separation differed significantly between group 1 (mean, -3.62 mm; SD, 0.79 mm) and group 2 (mean, 0.34 mm; SD, 0.14 mm; p <0.001). In conclusion, a totally implantable and bioresorbable device was successfully used to mobilize calvarial bone. Polymer contractility will likely constitute the basis of a new generation of bioresorbable distractors for use in craniofacial surgery.

Orbital fractures in craniofacial trauma in Göteborg: trauma scoring, operative techniques, and outcome.

In the 10-year period 1986-1996, 85 patients were admitted to our unit with craniofacial injuries, 56 of whom had orbital fractures. These were studied with respect to the type of injury, type and location of fracture, presence of ocular and intracranial injury, and associated injuries to the head and body, as well as operative techniques used. Both the patient's and the surgeon's opinion on the aesthetic result were noted. The patients were also given a questionnaire about their quality of life after the injury. Road traffic crashes accounted for 31 (55%) of the injuries, falls for 9 (15%), and horse-riding for 6 (11%). The Injury Severity Score (ISS) ranged from 4 to 41 (mean 18). Twelve also had eye injuries, which resulted in complete blindness in one eye in 4 (7%). Thirty patients had 41 neurological injuries (54%), frontal contusions being the most frequent diagnosis (n = 15). Exact repositioning with rigid fixation included bone grafting to the orbit in 11 patients, and the dominating bone graft was split calvarium (n = 5). Forty-two patients completed a questionnaire, 26 of whom (64%) had no aesthetic complaints. Seven of the 42 were too disabled to work one year after the injury. Re-exploration was infrequent and the aesthetic outcome, both in the surgeon's and the patient's opinion, was good. However, the older the patient, the worse the outcome.

Spring-mediated cranioplasty compared with the modified pi-plasty for sagittal synostosis.

The aim of this study was to compare the safety, morphological outcome, and degree of parental satisfaction of the new spring-mediated cranioplasty with those of the modified pi-plasty in the management of sagittal synostosis. Ten patients with non-syndromic sagittal synostosis treated with the spring-mediated cranioplasty were followed prospectively. A control group of 10 sex-matched patients operated on with the modified pi-plasty procedure was chosen. Cephalometric radiographs were obtained preoperatively and postoperatively at 1 year of age. Cephalic index, axial width ratio, length ratio, width ratio and height ratio were used as objective measures of outcome. Parents were sent a questionnaire to obtain a subjective aesthetic assessment of outcome. Significantly less blood replacement was required (p = 0.003), and shorter duration of postoperative anaesthesia (p = 0.030) and postoperative hospital stay (p = 0.013) were found in the spring-mediated cranioplasty group. There were no complications or deaths in either group. Also significant was the inter-group difference in the postoperative change in the height ratio (p = 0.030), the most change being seen in the spring group. The change in the subjective parental aesthetic evaluation of skull shape was significant in both groups. In conclusion, the spring-mediated procedure was morphologically more effective than the modified pi-plasty procedure in the management of sagittal synostosis with the additional benefits of less blood transfusion needed and shorter duration of hospital stay.

The biomechanical characteristics of cranial sutures are altered by spring cranioplasty forces.

BACKGROUND: The mechanical properties of the pediatric craniofacial complex allow dissipation of spring cranioplasty forces. Springs do not fully expand in situ and continue to transmit a continuous force until removal. The authors wished to investigate whether ongoing forces altered the biomechanical characteristics of cranial sutures. METHODS: Thirty New Zealand White rabbits were divided into five groups: spring expansion for 4, 7, and 10 weeks; early spring removal at 4 weeks followed by monitoring for 3 weeks; and a control group (n = 6 each). Cranial expansion was monitored using cephalometry. The left coronal suture then underwent load-displacement testing in a dynamometer. RESULTS: Relapse of cranial expansion was observed following early spring removal (mean, 6 percent; p = 0.017). Cranial suture thickness was significantly correlated to the length of spring insertion. Load displacement curves of sutures in all groups initially exhibited classic viscoelastic behavior. The treatment group developed intrasutural weakening before failure that was not observed in controls. The peak load before failure as a percentage of that observed in controls was 31 percent in the 4-week group (p = 0.001), 35 percent in the 7-week group (p = 0.000), and 45 percent in the 10-week group (p = 0.023). CONCLUSIONS: Cranial suture compliance is modified in the presence of continuous spring cranioplasty forces. Thickening of the coronal sutures, which have been expanded in a shear-like manner, increases their three-dimensional surface area and may contribute to the relative lack of relapse observed after early spring removal.

Cranial bone and suture strains incident to spring-assisted cranioplasty.

BACKGROUND: Spring-assisted cranioplasty transmits forces throughout the craniofacial complex that can be measured as strain. The strain magnitude in relation to normal background physiologic strains and the distribution of these strains are currently unknown. METHODS: Twenty New Zealand White rabbits were randomized into two groups: the treatment group, which included posterofrontal suture removal and spring insertion (n = 10); and the control group, which consisted of posterofrontal suture removal (n = 10). Strain gauges were placed across the interfrontal suture, both coronal sutures, and the frontal bone. Continuous strain recordings were made for 15 minutes after spring insertion. RESULTS: Physiologic strains caused by dural pulsation and intracerebral swelling measured were higher within sutures (40 to 50 microepsilon) than in bone (10 to 20 microepsilon). Spring activation produced large increases in strain across all sutures and bone. Compared with controls, tensile strains were 20 times higher in the frontal bone (mean, 341 microepsilon; p = 0.000), 15 times higher in the interfrontal suture (539 microepsilon; p = 0.000), and 21 times higher in the coronal suture (700 microepsilon; p = 0.000). Compressive strain in the left coronal suture confirmed a shear force at these sutures (-503 microepsilon; p = 0.000). The variability of background physiologic strain was not dampened by spring loading. CONCLUSIONS: Spring-assisted cranioplasty produces supraphysiologic strain in adjacent cranial bone and suture tissue. Mechanotransduction converts these forces into the biological processes that modulate calvarial morphology. Contrary to expectations, bone lateral to the spring insertion is subjected to tensile strain on its ectocranial surface. A compressive strain on its endocranial surface is likely because of bone flexion. This has implications for subsequent calvarial morphology.

Spring-assisted cranioplasty alters the growth vectors of adjacent cranial sutures.

BACKGROUND: Expansile cranial springs are used to treat selected cases of sagittal synostosis. After sagittal suturectomy, springs are placed perpendicular to the line of the synostosis. Normal growth across the coronal suture is approximately perpendicular to the suture line. To allow cranial expansion in the parietal direction, it is hypothesized that the normal growth vectors across the coronal sutures are altered. METHODS: Ten New Zealand White rabbits underwent suturectomy of the midline posterior frontal suture followed by insertion of an expansile spring. Radiologic markers were placed on either side of the normal coronal sutures (n = 20) perpendicular to the released suture. Serial radiology was performed up to 7 weeks. Growth vectors across the coronal suture were compared with those of 10 control rabbits. RESULTS: Dorsal cranial expansion was predominantly in an anterolateral direction in controls. The normal growth vector across the coronal suture occurred at an angle of -1 degree to the midline. A spring altered this growth vector to 63 degrees. Over 7 weeks, the cranial width increased 5.1 mm in rabbits with springs compared with 0.2 mm in the control group (p < 0.01). The increase in cranial length across the coronal suture was 1.82 mm in controls and 0.93 mm in rabbits with springs (p = 0.019). CONCLUSIONS: Application of a spring across a midline cranial suture alters the growth vector of the normal adjacent sutures. The spring greatly increases cranial width at the expense of some of the normal increase in cranial length over this period. This would be beneficial in correcting the cranial index in sagittal synostosis.

"Spectaclesplasty" periorbital rotation advancement in Crouzon syndrome.

Facial deformity in Crouzon syndrome is characterized by exophthalmos, exorbitism, mild hypertelorism, and maxillary hypoplasia with a Class III occlusion. The Göteborg craniofacial unit corrects this deformity in selected patients by the 2-stage procedure of "spectaclesplasty" followed by a Le Fort I maxillary osteotomy at skeletal maturity. "Spectacles" is a reference to the bilateral circumferential periorbital bony skeleton, and a spectaclesplasty is a differential rotation and advancement of this complex. Spectaclesplasty has been integrated as part of our protocol in managing Crouzon syndrome from birth to maturity. All patients who have undergone spectaclesplasty were retrospectively reviewed. A composite scoring system analyzing periorbital anatomy and aesthetics was used to compare the preoperative and most recent postoperative photographs. Complications and the need for ancillary procedures were recorded. Twenty-one patients have undergone spectaclesplasty since this technique was introduced in 1984. Mean follow-up time is 5 years 10 months. Compared with their preoperative aesthetics, the improvement was rated as excellent for 8 patients (38%), very good for 7 patients (33%), good for 5 patients (24%), and minimal for 1 patient (5%). No patient was rated as having no improvement. Mean perioperative blood loss was 111% of estimated red cell mass. Mean operative time was 6.4 hours. The mean duration of stay in the intensive care unit was 28 hours, and the mean hospital stay was 11 days. There were few complications and no incidences of mortality. Spectaclesplasty yields high-quality aesthetic results in most cases. It is our impression that spectaclesplasty en bloc rotation advancement of the periorbital bony skeleton can be safely performed before skeletal maturity of the lower face. Correction of the bony periorbital anatomy in early adolescence is important in alleviating psychosocial distress in this age group. In our hands, spectaclesplasty produces a more normal anatomic position of the periorbital soft tissues facilitating both function and aesthetics.

Spring-assisted remodeling for ventricular shunt-induced cranial deformity.

Ventricular shunt overdrainage may cause cranial vault collapse, deformation, and secondary craniosynostosis. There is a paucity of information in the literature about this condition or successful low morbidity methods to reshape the cranial vault. Spring-assisted cranioplasty was developed in the Göthenborg Craniofacial Unit and is part of our routine protocol for the treatment of selected patients with craniosynostosis. The same treatment principles were applied to skull deformity secondary to ventricular shunt-associated deformity. Four patients with scaphocephaly secondary to ventricular shunting were treated using expansile springs. Three patients had a secondary sagittal synostosis requiring osteotomy. A further patients' sagittal suture was still patent, and this was expanded without osteotomy. Near normalization of the cranial index and significant aesthetic improvement of the cranial vault were noted in all cases. The mean preoperative cranial index increased from 0.60 to 0.71 within 4 months after surgery. The limited dissection and short operative time enabled minimal morbidity and blood loss compared with that expected with traditional craniofacial reshaping techniques. Patients with ventricular shunt-associated cranial deformity often have associated medical problems. Cranial bone is often in short supply and its quality less than optimal. In this situation, spring-assisted surgery is straightforward and offers significant advantages over traditional craniofacial reshaping techniques.

Spring-assisted cranioplasty vs pi-plasty for sagittal synostosis--a long term follow-up study.

Spring-assisted cranioplasty (SAS) has been used for the treatment of selected cases of sagittal synostosis at our unit routinely since 1998. In order to assess the long-term outcomes of this procedure, we compared the clinical data and morbidity with the pi-plasty technique, our previous standard procedure for the treatment of such children. The first 20 consecutive patients who underwent SAS for isolated sagittal synostosis with complete records, and who were 3 years old at the time of this study, were included. Twenty patients with a pi-plasty performed in the period immediately preceding the spring group acted as a control group. Cephalograms (preoperative, 1-year and 3-year), clinical examination, medical record data, medical photography, and a questionnaire (spring-group only) were used to evaluate and compare these two groups. The mean age of the spring group was 3.5 months (2.5-5.5) and the pi-plasty group 7.1 months (4-15.5) of age at surgery. There were no deaths in either group. There was a higher rate of complications in the pi-plasty group. The skull morphology was similar preoperatively in both groups but slightly different at the 3-year follow-up. The mean cephalic index (CI) in the spring group was 72 at 1 year of age and 71 at 3 years of age, indicating a minor relapse. The pi-plasty group had a mean CI of 73 at 3 years of age. The length was the same in both groups however the pi-plasty group had a lower height (mean 2 mm) and wider biparietal distance (mean 5 mm). All parents of the spring group were highly satisfied with the aesthetic results achieved, would undergo the operation again, and would recommend it to others with scaphocephaly. It was concluded that the two groups of surgery resulted in a quite similar morphologic outcome. The pi-plasty group had a cephalic index marginally closer to the normal range at 3 years of age. The spring group was superior with respect to blood loss, transfusion requirements, operative time, ICU time, recovery time, and total hospital stay.

The evolving role of springs in craniofacial surgery: the first 100 clinical cases.

BACKGROUND: The use of springs in craniofacial surgery originated at Sahlgrenska University Hospital in 1997 as a way of remodeling the cranial vault postoperatively. METHODS: The hospital records of the first 100 operations involving spring placement were analyzed retrospectively. Demographic, perioperative, and postoperative data were recorded. RESULTS: Two hundred forty-six springs were used in 96 patients. Results for sagittal, metopic, bicoronal, multiple synostoses, and midface surgery are presented. In total, five patients (5 percent) required further surgery because of undercorrection. There were no major complications. Spring dislodgement (5 percent) was the most common complication in early cases. Raised intracranial pressure resulted in a protocol change with the use of compressive springs. The data compare favorably with those of standard craniofacial procedures performed in the same unit. CONCLUSIONS: This therapeutic modality in craniofacial surgery has allowed minimization of the extent of surgery without compromising clinical outcomes. Springs have now become part of the authors' treatment protocol for craniosynostosis and midface surgery. The authors have shown the use of these techniques to be safe and, in selected situations, to offer significant advantages over other methods of treatment.

Spring-assisted correction of hypotelorism in metopic synostosis.

BACKGROUND: Metopic synostosis, apart from the pointed forehead, typically is characterized by hypotelorism with egg-shaped orbits on cephalography and the frontoorbital axis parallel or even converging superiorly. The frontoorbital axis angle is a novel parameter for analyzing and describing the orientation of the orbits. Current methods of surgery often result in undercorrection of the almost ever-present hypotelorism. The present study was performed to analyze a new technique, capable in this respect, using steel wire springs in conjunction with a cranioplasty. METHODS: A retrospective study of 23 metopic synostosis patients operated on between 1999 and 2004 was conducted. A strip midline craniectomy and frontal reshaping were combined with the insertion of a steel wire spring across the midline craniectomy, forcing lateral displacement of the orbits. Preoperative and postoperative follow-up cephalograms were obtained, and the bony medial interorbital distance was measured and compared with the bony medial interorbital distance of a control group. Perioperative data and complications were noted. RESULTS: Preoperative mean bony interorbital distance was 10.6 mm (range, 7.7 to 13.2 mm). It increased to 15.7 mm (range, 10.4 to 22 mm) at 1.5 months postoperatively and to 16.2 mm (range, 10.9 to 24.5 mm) 5 months postoperatively. Results as judged clinically ranged from little effect to a definitive overcorrection. The frontoorbital axis was improved in every case. Average frontoorbital axis was -4 degrees (range, -33 to 23 degrees) preoperatively and 28 degrees (range, 11 to 46 degrees) postoperatively. CONCLUSION: It was concluded that a spring used together with a cranioplasty is a powerful tool for the correction of both hypotelorism and orbital shape in trigonocephaly.

Women with Saethre-Chotzen syndrome are at increased risk of breast cancer.

The Saethre-Chotzen syndrome is an autosomal, dominantly inherited craniosynostosis caused by mutations in the basic helix-loop-helix transcription factor gene TWIST1. This syndrome has hitherto not been associated with an increased risk of cancer. However, recent studies, using a murine breast tumor model, have shown that Twist may act as a key regulator of metastasis and that the gene is overexpressed in subsets of sporadic human breast cancers. Here, we report a novel association between the Saethre-Chotzen syndrome and breast cancer. In 15 Swedish Saethre-Chotzen families, 15 of 29 (52%) women carriers over the age of 25 had developed breast cancer. At least four patients developed breast cancer before 40 years of age, and five between 40 and 50 years of age. The observed cases with breast cancer (n = 15) are significantly higher than expected (n = 0.89), which gives a standardized incidence ratio (SIR) of 16.80 (95% CI 1.54-32.06). Our finding of a high frequency of breast cancer in women with the Saethre-Chotzen syndrome identifies breast cancer as an important and previously unrecognized symptom characteristic of this syndrome. The results strongly suggest that women carriers of this syndrome would benefit from genetic counseling and enrolment in surveillance programs including yearly mammography. Our results also indicate that the TWIST1 gene may be a novel breast cancer susceptibility gene. Additional studies are, however, necessary to reveal the mechanism by which TWIST1 may predispose to early onset breast cancer in Saethre-Chotzen patients.