Effects of lateral retinacular release on the lateral stability of the patella.

The objective of this cadaveric study was to evaluate quantitatively the effects of lateral retinacular release on the lateral stability of the patella. A materials testing machine was used to displace the patella of seven cadaveric specimens 10 mm laterally while measuring the required force, with 175 N quadriceps tension. The patella was connected via a ball-bearing patellar mounting 10 mm deep to the anterior surface to allow rotations. Patellar force--displacement behaviour was tested from 0 degrees to 60 degrees knee flexion. At 0 degrees , 10 degrees and 20 degrees flexion the mean force required to displace the patella 10 mm laterally was reduced significantly due to lateral retinacular release, by 16-19%. The average force required to displace the patella was also reduced for larger flexion angles, although this was not statistically significant. These findings suggest that lateral retinacular release may not be appropriate in treatment of patellar lateral instability.

Posterior compact Cotrel-Dubousset instrumentation for occipitocervical, cervical and cervicothoracic fusion.

The authors report on 32 consecutive patients with instability at the craniocervical, cervical and cervicothoracic regions suffering from various pathologies, who were treated with posterior instrumentation and fusion using the posterior hooks-rods-plate cervical compact Cotrel-Dubousset (CCD) instrumentation alone or, in three patients, in combination with anterior operation. The patients were observed postoperatively for an average of 31 months (range 25-44 months) and evaluated both clinically and radiographically using the following parameters: spine anatomy and reconstruction, sagittal profile, neurologic status, functional level, complications and status of arthrodesis. All patients but one (who died) achieved a solid arthrodesis based on plain and flexion/extension roentgenograms. Cervical lordosis (skull-C7) and cervicothoracic kyphosis (C7-T2) was improved by instrumentation towards a physiological lateral curve by an average of 33% (P<0.05) and 28% (P<0.05) respectively. Anterior vertebral olisthesis was reduced in the craniocervical and cervicothoracic region, by 73% and 90% respectively. At final follow-up there was an improvement of the neurologic Frankel status by an average of 1.2 grades and of myelopathy in 75% of the operated patients. Good to excellent functional results were seen in 77% of the operated patients, while acute and chronic pain was reduced by an average of 2.4 grades, on a scale of 0-3, in operated patients. No neurovascular or pulmonary complications arose from surgery. There was no significant change in lateral spine profile and olisthesis at the latest follow-up evaluation. There were no instrument-related failures. One patient requested hardware removal in the hope of reducing postoperative pain in the cervicothoracic region. The poor and fair results were related to the lack of improvement of neurologic impairment and myelopathy. The results of this study demonstrate that cervical CCD instrumentation applied in the region of the skull to the upper thoracic region for various disorders is a simple and safe instrumentation that restores lateral spine alignment, improves the potential for a solid fusion and offers sufficient functional results in the vast majority of the operated patients. However, the use of hooks in spinal stenosis is contraindicated.

An individualized approach for the implantation of a humeral prosthesis with the proper retroversion in fractures.

We applied a new methodology in 7 patients with a fracture of the upper humeral head that required hemiarthroplasty, to implant a humeral prosthesis with an individualized posterior version. Our goal was to determine preoperatively the distance from the posterior edge of the bicipital groove where the lateral fin of the humeral prosthesis should sit, in order to reproduce the individual retroversion during surgery. Using three computed tomography scan sections of the upper humerus and image processing software, we estimated the above-mentioned distance in the sound humerus and implanted the prosthesis in each patient accordingly. The differences in retroversion between the left and right humeral heads permit a better approximation to normal applying this methodology than inserting the prosthesis in a standard retroversion.

The bicipital groove as a landmark for orientation of the humeral prosthesis in cases of fracture.

We studied 45 dry cadaveric humeri to determine whether the bicipital groove of the humerus can be used as a landmark for a proper, individualized orientation of a humeral prosthesis, especially in the case of a fracture. We performed 3 computed tomography sections (at a level just below the lower portion of the head, at the middle of the humeral head, and at a distance 5 cm below the first section), and we used special software for 3-dimensional image processing. To reproduce the individual posterior version of the head, when a humeral prosthesis is implanted for fracture, the lateral fin of the prosthesis should be a mean distance 5.2 +/- 2.6 mm (-1.5 to 10.7 mm) from the posterior edge of the bicipital groove. If the lateral fin of the humeral prosthesis seats just behind the posterior edge of the bicipital groove, a difference of -6.3 degrees to 41.7 degrees from the normal posterior version occurs. A new, simple methodology for an individualized posterior version of a humeral prosthesis in cases of fracture is proposed. We applied this in 6 consecutive patients with fracture of the humeral head that required hemiarthroplasty.

Treatment of unstable thoracolumbar and lumbar spine injuries using Cotrel-Dubousset instrumentation.

STUDY DESIGN: In this prospective study, the results of treating unstable thoracolumbar and lumbar injuries with Cotrel-Dubousset instrumentation were investigated. OBJECTIVE: To determine the pain and work status of the patients, to evaluate neurologic status, and to assess the efficacy of instrumentation in the short term. SUMMARY OF BACKGROUND DATA: Short-segment pedicle screw construct is the method of choice for reduction and stabilization of unstable thoracolumbar spinal injuries. Many investigators have recently reported a high rate of instrument failure. In this study, the use of segmental transpedicular fixation two levels above the kyphosis decreased instrument failure and sagittal collapse. METHODS: Thirty patients, who had unstable thoracolumbar and lumbar spinal injuries, underwent application from a posterior approach of Cotrel-Dubousset instrumentation two levels above and one below at the thoracolumbar junction and short segment fixation in the lumbar area. Radiologic parameters were evaluated before and after surgery. RESULTS: The mean follow up was 31 months (range, 25-49) months. There were statistically significant differences between the pre- and postoperative values in all radiologic parameters. Neurologic status improved in 70% of the patients, with a mean Frankel grade of 1.3 grades. CONCLUSIONS: Cotrel-Dubousset instrumentation provided spinal stability in unstable injuries, forming a rigid construct and restoring physiologic thoracolumbar and lumbar postural contours because of its highly corrective effect in the sagittal profile with no loss of correction.

Simultaneous double interphalangeal dislocation in a finger.

A rare case of simultaneous dorsal dislocation of both interphalangeal joints in a finger is presented. Review of reported cases revealed that this injury usually occurs on the ulnar side of the hand of young male athletes and has a good outcome with conservative treatment.