[Results of surgical therapy of orbital abnormalities]

Surgical correction of grade III hypertelorism

Orbital hypertelorism is an increased distance between the bony orbits and can be caused by frontonasal malformations, craniofacial clefts, frontoethmoidal encephaloceles, glial tumors or dermoid cysts of the root of the nose, and various syndromic or chromosomal disorders. We report a series of 7 cases of hypertelorism that were treated in our hospital. The underlying causes in our series were craniofacial clefts 0 to 14 (4 cases), craniofacial clefts 1 to 12 (1 case), and frontonasal encephalocele (2 cases), all congenital. Surgical techniques used to correct the deformity were box osteotomy and medial wall osteotomy with or without calvarial and rib grafts. A few of our cases were reoperations with specific challenges.

[Rapid prototyping in planning reconstructive surgery of the head and neck. Review and evaluation of indications in clinical use]

PURPOSE

The aim was to define the indications for use of rapid prototyping models based on data of patients treated with this technique.

PATIENTS AND METHODS

Since 1987 our department has been developing methods of rapid prototyping in surgery planning. During the study, first the statistical and reproducible anatomical precision of rapid prototyping models was determined on pig skull measurements depending on CT parameters and method of rapid prototyping.

RESULTS

Measurements on stereolithography models and on selective laser sintered models confirmed an accuracy of +/-0.88 mm or 2.7% (maximum deviation: -3.0 mm to +3.2 mm) independently from CT parameters or method of rapid prototyping, respectively. With the same precision of models multilayer helical CT with a higher rate is the preferable method of data acquisition compared to conventional helical CT. From 1990 to 2002 in atotal of 122 patients, 127 rapid prototyping models were manufactured: in 112 patients stereolithography models, in 2 patients an additional stereolithography model, in 2 patients an additional selective laser sinter model, in 1 patient an additional milled model, and in 10 patients just a selective laser sinter model.

CONCLUSION

Reconstructive surgery, distraction osteogenesis including midface distraction, and dental implantology are proven to be the major indications for rapid prototyping as confirmed in a review of the literature. Surgery planning on rapid prototyping models should only be used in individual cases due to radiation dose and high costs. Routine use of this technique only seems to be indicated in skull reconstruction and distraction osteogenesis.