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Biomedical subjects

Rudy Reindl

Publications and source records attributed to Rudy Reindl.

7 recordsLinked to original sources
PubMed2006

Percutaneous insertion of a proximal humeral locking plate: an anatomic study.

This cadaveric study sought to evaluate the feasibility of applying a locking proximal humerus plate with a novel minimally invasive technique. A unique pre-contoured locking plate was placed on cadaveric proximal humeri through a described minimally invasive approach. Proximity of the plate and screws to the axillary nerve and their respective surgical tracks were quantified. Safe screw hole placement with respect to the axillary nerve was determined. Risk of entrapment of the nerve beneath the plate was evaluated. Three of the holes near the middle of the locking plate consistently intersected the course of the axillary nerve and were unsafe for percutaneous placement of the screws. The axillary nerve could be palpated during the course of surgery and easily protected from injury. No entrapment of the axillary nerve occurred using this minimally invasive technique. The screw-in locking guide cannot be used with this technique as it caused tenting of the axillary nerve. Placement of a locking proximal humerus plate via a minimally invasive lateral trans-deltoid approach is safe if the locking screws are limited to superior and inferior holes. This can be done safely without entrapment of the axillary beneath the plate. Plate fixation of proximal humerus fractures may now be more desirable with the use of this approach.

Acromion↗
PubMed2006

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model.

BACKGROUND: Newer internal fixation devices with a locking mechanism between the plate and the screw have recently been released. The efficacy of these plates in the proximal humerus has yet to be fully described. There is a need to compare the biomechanical properties of efficacy of plate fixation with or without locking screws for surgery of two-part proximal humerus fractures. Multiple-plane locking plate and cloverleaf plate designs were tested to determine their ability to maintain fixation on the humeral head. METHODS: Eight matched pairs of cadaveric shoulders with 7-millimeter osteotomy defects at the surgical neck simulating two-part fractures of the proximal humerus were loaded to failure in thirty degrees of glenohumeral abduction. One side was repaired with a proximal humerus locking plate and the other with a cloverleaf plate. The rotator cuff musculature was then loaded via a servo-hydraulic testing machine under displacement control to simulate the deforming forces present in vivo. FINDINGS: The average maximum load to failure was greater in proximal humerus locking plates than in cloverleaf plates (876 versus 712; P=0.04). INTERPRETATION: In the cadaveric, two-part proximal humerus fracture model that was created, the locking plate displayed significantly greater holding power of the humeral head. Clinical relevance is unproven but may be manifested in vivo as improved early range of motion exercises and functional outcome.

Aged↗
PubMed2006

Harvesting local cylinder autograft from adjacent vertebral body for anterior lumbar interbody fusion: surgical technique, operative feasibility and preliminary clinical results.

Autogenous iliac crest has long served as the gold standard for anterior lumbar arthrodesis although added morbidity results from the bone graft harvest. Therefore, femoral ring allograft, or cages, have been used to decrease the morbidity of iliac crest bone harvesting. More recently, an experimental study in the animal showed that harvesting local bone from the anterior vertebral body and replacing the void by a radio-opaque beta-tricalcium phosphate plug was a valid concept. However, such a concept precludes theoretically the use of posterior pedicle screw fixation. At one institution a consecutive series of 21 patients underwent single- or multiple-level circumferential lumbar fusion with anterior cages and posterior pedicle screws. All cages were filled with cancellous bone harvested from the adjacent vertebral body, and the vertebral body defect was filled with a beta-tricalcium phosphate plug. The indications for surgery were failed conservative treatment of a lumbar degenerative disc disease or spondylolisthesis. The purpose of this study, therefore, was to report on the surgical technique, operative feasibility, safety, benefits, and drawbacks of this technique with our primary clinical experience. An independent researcher reviewed all data that had been collected prospectively from the onset of the study. The average age of the patients was 39.9 (26-57) years. Bone grafts were successfully harvested from 28 vertebral bodies in all but one patient whose anterior procedure was aborted due to difficulty in freeing the left common iliac vein. This case was converted to a transforaminal interbody fusion (TLIF). There was no major vascular injury. Blood loss of the anterior procedure averaged 250 ml (50-350 ml). One tricalcium phosphate bone plug was broken during its insertion, and one endplate was broken because of wrong surgical technique, which did not affect the final outcome. One patient had a right lumbar plexopathy that was not related to this special technique. There was no retrograde ejaculation, infection or pseudoarthrosis. One patient experienced a deep venous thrombosis. At the last follow up (mean 28 months) all patients had a solid lumbar spine fusion. At the 6-month follow up, the pain as assessed on the visual analog scale (VAS) decreased from 6.9 to 4.5 (33% decrease), and the Oswestry disability index (ODI) reduced from 48.0 to 31.7 with a 34% reduction. However, at 2 years follow up there was a trend for increase in the ODI (35) and VAS (5). The data in this study suggest that harvesting a cylinder of autograft from the adjacent vertebral body is safe and efficient. Filling of the void defect with a beta-tricalcium phosphate plug does not preclude the use of posterior pedicle screw stabilization.

Adult↗
PubMed2006

Anterior reduction for cervical spine dislocation.

STUDY DESIGN: Retrospective analysis of a prospectively followed cohort. OBJECTIVE: Long-term evaluation of patients with anterior stabilization for dislocations of the cervical spine. SETTING: Level 1 trauma center. SUMMARY OF BACKGROUND DATA: Anterior stabilization of unstable cervical spine injuries is gaining popularity. However, the method of open reduction is controversial. METHODS: Forty-one consecutive patients with unstable dislocations/subluxations of the subaxial cervical spine were included. Closed reduction was attempted in all patients using Gardner-Wells traction. If this failed, an anterior open reduction was performed. Tricortical iliac crest autograft and anterior plating was used. Patients were assessed for: 1) rate of successful reduction and stabilization using only the anterior surgical approach; and 2) complications and long-term clinical and radiologic outcome. RESULTS: Two of eight (25%) anterior open reductions failed requiring posterior surgery. One of these patients had associated pedicle fractures with horizontal rotation of the lateral masses. All grafts had healed successfully at the most recent follow-up visit. Moderate neck discomfort was found in 5 of 41 patients. Significant neurologic improvement was observed. CONCLUSIONS: Most subluxations/dislocations of the subaxial cervical spine can be reduced using Gardner-Wells traction and successfully stabilized with anterior surgery alone. If closed reduction fails, anterior open reduction is successful in the majority of cases.

Adolescent↗
PubMed2005

Anatomical risks of using supra-acetabular screws in percutaneous internal fixation of the acetabulum and pelvis.

We conducted a study to determine whether a lag screw placed percutaneously at the level of the pelvic brim for treatment of iliac fracture risks injury to the lateral femoral cutaneous nerve (LFCN). A 4-mm Kirschner wire (K-wire) was placed percutaneously into each of 8 human cadaveric hemipelvises (4 pelvises) at the level of the pelvic brim to represent the path of screw placement. Under fluoroscopic guidance, each K-wire was advanced from the anteroinferior iliac spine toward the posterior iliac crest. Cadavers were dissected at study end. Proximity of the LFCN to the percutaneously inserted K-wire was the main outcome measured. In 4 of the 8 hemipelvises, the LFCN was disrupted; in 3 hemipelvises, it was within 4 mm of the K-wire; in the last hemipelvis, it was 23 mm away. LFCNs varied anatomically from 1 to 5 branches; disruptions occurred more in LFCNs with multiple branches than in those with 1 branch. The results suggest considerable risk for injury to the LFCN during percutaneous fixation of iliac and acetabular fractures using a percutaneous screw at the level of the pelvic brim.

Acetabulum↗
PubMed2003

Anterior instrumentation for traumatic C1-C2 instability.

STUDY DESIGN: Technical note, case report. and review of literature. OBJECTIVE: Description of anterior transarticular internal fixation for traumatic C1-C2 instability. SUMMARY OF BACKGROUND DATA: The currently effective posterior approaches for instrumentation of the C1-C2 junction require considerable soft tissue dissection and prone patient positioning. Some medical and anatomic conditions restrict the posterior approach. MATERIALS AND METHODS: An odontoid screw and anterior transarticular C1-C2 screws were used to instrument an unstable injury at this junction. The lesion consisted of a type II dens fracture and C1 ring disruption. Two high-quality fluoroscopy machines, a radiolucent OSI fracture table, and the Synframe (Synthes, Paoli, PA) retraction system are used for this procedure. The implant of choice is the 4.0-mm cannulated titanium screw. RESULTS: At 4-month follow-up, successful stabilization without failure of hardware is documented. The patient's neurologic status is stable, with a minor residual left upper extremity motor deficit. The patient has restricted C-spine rotation but no neck pain with movement. CONCLUSION: Anterior stabilization through a standard Smith-Robinson approach of the C1-C2 junction with screws into the odontoid and the lateral masses of C1 is effective. Supine positioning and minimal soft tissue dissection are advantages of this method over standard posterior transarticular instrumentation. Knowledge of the local anatomy, strict adherence to the operative protocol, and high-quality fluoroscopy avoid potential surgical complications.

Bone Screws↗