[The radical minimal access thoracoplasty by funnel chest in adults].

A new technique of radical thoracoplasty, performed with a small size incision, using the sternocostal complex fixation with nitinol plates with shape memory and the surgical toolkit required for the purpose, has been successfully introduced. 23 patients underwent surgery using the technique. Tree patients had early postoperative complications: 2 cases of exudative pleurisy and 1 case of bronchitis aggravation. Good cosmetic results was achieved in all operated patients. The mechanical ground of the technique is based on the use of the effective force of the sternum traction and the pressure of the plate on the tissues below. The main advantage of the method is avoidance of the transverse sternotomy.

Cranial bone flap fixation using a new device (Cranial LoopTM).

BACKGROUND: Fixation of bone flaps after craniotomy is a routine part of every neurosurgical procedure and there are various options to fixate the bone flap. In this paper, we report on a new cranial bone flap fixation d(Cranial Loop) implanted in 35 consecutive patients. METHODS: The principle of cranial loop is the same as that of a tie rope. With a simple "pull and tighten" movement, the device is implanted without the need for additional instruments. The cranial loop is made of PEEK [poly(aryl)-ether-ether-ketone] material with the main advantage of being artifact free on postoperative imaging. In 35 consecutive patients operated by a single surgeon, the cranial loops were used for bone flap fixation. All patients had a postoperative CT scanning and a follow-up period of at least 9 months. RESULTS: In all patients, the bone flap could be easily fixed with 3 or more cranial loops without difficulties or material breakage, this within 3 min. The postoperative infection rate was 0%, postoperative hemorrhage (either epi/sub or intraparenchymatous) requiring reoperation was 0%. None of the patients experienced a bone flap dislocation, either clinically or on the postoperative CT-images. 3D CT-scanning revealed all of the flaps being in a good anatomic position. CONCLUSIONS: Although this is a preliminary report in a relatively small number of patients, we are of opinion that the cranial loop is a very fast, easy, and safe to use bone flap fixation device with the main advantage of the absence of artifacts on postoperative CT or MR imaging and lack of cosmetic disadvantage.

A laparoscopic approach to ventriculoperitoneal shunt placement with a novel fixation method for distal shunt catheter in the treatment of hydrocephalus.

BACKGROUND: The laparoscopically assisted ventriculoperitoneal (VP) shunt has been widely used in the clinical treatment of hydrocephalus for its simplicity and reliability. Despite significant improvements in shunt procedures, shunt complications remain common. Our clinical experiences suggest that the fixation of the distal (peritoneal) shunt catheter using threads and hemoclips may partially contribute to complications of the distal shunt including obstruction of the shunt and infection. In this study, we explored a novel fixation method in the laparoscopically assisted VP shunt with use of the liver falciform ligament as a natural support for fixation of the distal shunt catheter. METHODS: 10 patients with hydrocephalus underwent laparoscopically assisted VP shunt and the distal shunt catheter was placed into the hepatodiaphragmatic space and the catheter was traversed through 2-3 drilled holes in the liver falciform ligament without using any artificial material for fixation. RESULTS: In all the patients who received surgery with the adopted new procedure the clinical symptoms were alleviated. The size of cerebral ventricles returned to normal after 1 week. The distal catheters were in the hepatodiaphragmatic space in 9 of 10 patients, while in 1 patient it migrated to the peritoneal cavity underneath the liver. All the 9 patients were followed up for 1 year and no surgery-related catheter obstructions and infections were observed. CONCLUSIONS: The modified laparoscopically assisted VP shunt in the treatment of hydrocephalus with fixation of the distal shunt catheter to a natural anatomic structure could potentially reduce the necessity of repeat surgery for addressing the complications caused by catheter obstruction and infections, reduce the chance of adhesions, and would be of benefit to those patients who need future revisions.

A new bone surrogate model for testing interbody device subsidence.

STUDY DESIGN: An in vitro biomechanical study investigating interbody device subsidence measures in synthetic vertebrae, polyurethane foam blocks, and human cadaveric vertebrae. OBJECTIVE: To compare subsidence measures of bone surrogates with human vertebrae for interbody devices varying in size/placement. SUMMARY OF BACKGROUND DATA: Bone surrogates are alternatives when human cadaveric vertebrae are unavailable. Synthetic vertebrae modeling cortices, endplates, and cancellous bone have been developed as an alternative to polyurethane foam blocks for testing interbody device subsidence. METHODS: Indentors placed on the endplates of synthetic vertebrae, foam blocks, and human vertebrae were subjected to uniaxial compression. Subsidence, measured with custom-made extensometers, was evaluated for an indentor seated either centrally or peripherally on the endplate. Failure force and indentation stiffness were determined from force-displacement curves. RESULTS: Subsidence measures in human vertebrae varied with indentor placement: failure forces were higher and indentors subsided less with peripheral placement. Subsidence measures in foam blocks were insensitive to indentor size/placement; they were similar to human vertebrae for centrally placed but not for peripherally placed indentors. Although subsidence measures in synthetic vertebrae were sensitive to indentor size/placement, failure force and indentation stiffness were overestimated, and subsidence underestimated, for both centrally placed and peripherally placed indentors. CONCLUSION: The synthetic endplate correctly represented the human endplate geometry, and thus, failure force, stiffness, and subsidence in synthetic vertebrae were sensitive to indentor size/placement. However, the endplate was overly strong and thus synthetic vertebrae did not accurately model indentor subsidence in human cadaveric vertebrae. Foam blocks captured subsidence measures more accurately than synthetic vertebrae for centrally placed indentors, but because of their uniform density were not sufficiently robust to capture changes generated from different indentor sizes/placements. The current bone surrogates are not accurate enough in terms of material property distribution to completely model subsidence in human cadaveric vertebrae.

Biomechanical optimization of different fixation modes for a proximal femoral L-osteotomy.

BACKGROUND: Numerous proposed surgical techniques have had minimal success in managing greater trochanter overgrowth secondary to retarded growth of the femoral capital epiphysis. For reconstruction of residual hip deformities, a novel type of proximal femur L-osteotomy was performed with satisfactory results. Although the clinical outcome was good, the biomechanical characteristics of the femur after such an osteotomy have not been clearly elucidated. Therefore, this study presents a three dimensional finite element analysis designed to understand the mechanical characteristics of the femur after the L-osteotomy. METHODS: A patient with left hip dysplasia was recruited as the study model for L-osteotomy. The normal right hip was used as a reference for performing the corrective surgery. Four FEA models were constructed using different numbers of fixation screws but the same osteotomy lengths together with four FEA models with the same number of fixation screws but different osteotomy lengths. The von Mises stress distributions and femoral head displacements were analyzed and compared. RESULTS: The results revealed the following: 1). The fixation devices (plate and screws) sustained most of the external loading, and the peak value of von Mises stress on the fixation screws decreased with an increasing number of screws. 2). Additional screws are more beneficial on the proximal segment than on the distal segment for improving the stability of the postoperative femur. 3). The extent of osteotomy should be limited because local stress might be concentrated in the femoral neck region with increasing length of the L-osteotomy. CONCLUSION: Additional screw placement on the proximal segment improves stability in the postoperative femur. The cobra-type plate with additional screw holes in the proximal area might improve the effectiveness of L-osteotomies.