Biomedical subjects

R K Leighton

Publications and source records attributed to R K Leighton.

12 recordsLinked to original sources

PubMed2006

Assessment of fragment micromotion in distal femur fracture fixation with RSA.

To assess fragment micromotion in three fracture fixation constructs 18 composite femur models were sectioned to create AO-C3 fractures and fixed using the Less Invasive Stabilization System (LISS), Dynamic Condylar Screw (DCS), or the Condylar Buttress Plate (CBP). Tantalum beads were attached to each fracture fragment. The constructs were tested for permanent deformation after cyclical loading (amplitude = 242.2N) and elastic deformation during static loading with 490.5N. Radiographs were taken before loading and then after unloading to determine permanent deformation or during loading to determine elastic deformation. We used RSA to quantify the six degrees of freedom interfragmentary maximum total motion, strain, and stress. For maximum total motion the CBP had more permanent deformation and two failures, whereas the LISS underwent the greatest elastic deformation. LISS and CBP had the highest strain conditions in the fracture gap and LISS had the greatest stress movements between fragments, all of which exceeded the upper limits for bone healing. LISS and CBP may not be indicated for comminuted fractures due to the high degree of flexibility of the LISS, resulting in high stress and strain conditions and susceptibility to catastrophic failure and high strain conditions with the CBP.

Elasticity↗

PubMed2001

Is homologous blood transfusion a risk factor for infection after hip replacement?

OBJECTIVES: To assess the risk of postoperative infection associated with blood transfusion in patients who undergo primary total hip arthroplasty. DESIGN: A retrospective cohort study. SETTING: Victoria General Hospital, Halifax, (a tertiary-care centre). PATIENTS: All patients who underwent primary total hip replacement between 1990 and 1995 (N = 1206). INTERVENTIONS: Hip replacement with or without perioperative blood transfusion. OUTCOME MEASURES: The rate of postoperative infection, the number of blood transfusions, patient age and sex, duration of surgery and the surgeon who performed the procedure. Victoria General Hospital medical records, the transfusion services record and the Dalhousie University Hip Study databases were integrated and analyzed using a standard statistical package. RESULTS: The incidence of infection postoperative was 9.9% overall, 8.4% in patients receiving no transfusion, and 14% in those receiving homologous transfusion (p = 0.035). There were no infections in the 11 patients who received an autologous blood transfusion. Significant predictors of postoperative infection were sex, age and duration surgery; these were not confounding variables multivariate analysis). Neither the operating surgeon nor the blood product transfused affected the infection rate. CONCLUSIONS: These findings suggest an increased risk of postoperative infection in patients who undergo primary hip replacement and receive homologous blood transfusions perioperatively.

Arthroplasty, Replacement, Hip↗

PubMed2000

Unicondylar knee arthroplasty: a cementless perspective.

OBJECTIVE: To compare the results of cementless unicondylar knee arthroplasty (UKA) with those already reported in a similar study on cemented UKA. DESIGN: A case-series cross-sectional study. SETTING: The Queen Elizabeth II Health Sciences Centre, Dalhousie University, Halifax. PATIENTS: Fifty-one patients who underwent a total of 57 UKAs between May 1989 and May 1997. Inclusion criteria were osteoarthritis involving the predominantly the medial compartment of the knee, relative sparing of the other compartments, less than 15 degrees of varus, minimal knee instability, and attendance at the postoperative clinical visit. INTERVENTION: Cementless UKA. MAIN OUTCOME MEASURES: Clinical parameters that included pain, range of motion and the Knee Society Clinical Knee Score. Roentgenographic parameters that included alpha, beta, gamma and sigma angles and the presence of periprosthetic radiolucency or loose beads. RESULTS: Age, weight, gender and follow-up interval did not significantly affect the clinical results in terms of pain, range of motion or knee score. Knees with more than 1 mm of radiolucency had significantly lower knee scores than those with no radiolucency. Knees that radiologically had loose beads also had significantly lower knee scores. The clinical outcomes of cementless UKA were comparable to those already reported on cemented UKA. Cementless femurs had less radiolucency than the cemented femurs, whereas cementless tibias had more radiolucency than their cemented counterparts. CONCLUSIONS: Cementless UKA seems to be as efficacious as cemented UKA. However, there is some concern about the amount of radiolucency in the cementless tibial components. A randomized clinical trial comparing both cementless and cemented tibial components with a cementless femur (hybrid knee) is needed to further assess this controversial issue in UKA.

Aged↗

PubMed1997

Late displacement of a fracture dislocation at the lumbosacral junction. A case study.

STUDY DESIGN: This is a retrospective single-patient case report with a literature review. OBJECTIVE: To report on an uncommon injury: traumatic fracture-dislocation of the lumbosacral junction with delayed displacement. SUMMARY OF BACKGROUND DATA: Only 31 cases of traumatic fracture-dislocation of the lumbosacral junction were found in the English literature. Only three previous reports refer to this injury occurring with a posterior displacement. This is the first report of this type of injury displacing in a delayed manner. METHODS: Chart review. RESULTS: Open reduction, Arbeitsgemeinschaft fur Osteosynthesefargen instrumentation, and interbody fusion resulted in a satisfactory clinical result with no neurologic impairment. CONCLUSIONS: The present study reports a very rare injury consisting of traumatic dislocation of the lumbosacral joint, presenting with displacement 2 months after injury. The patient was treated successfully with surgery even though the injury displaced in a delayed fashion.

Adult↗

PubMed1996

Techniques for reduction and posterior fixation through the anterior approach.

Pelvic fractures, especially those of a Malgaigne type, frequently occur in patients who are polytraumatized. Sacroiliac disruption reflects a massive, disruptive energy force with concurrent soft tissue injury. Fixation through an anterior approach facilitates the accurate and stable fixation and avoids many soft tissue wound problems associated with open anterior approaches. The absolute indication for the approach is a posterior disruption of the sacroiliac joint with or without an iliac wing fracture that is unreducible by closed reduction techniques.

Bone Plates↗

PubMed1996

Effect of proximal and distal venting during intramedullary nailing.

During intramedullary manipulation, 2 main phenomena occur. A dramatic rise in intramedullary pressure occurs followed by intravasation of damaged marrow tissue. There are concerns about the development of increased interosseous pressure during reaming and the potential for this to contribute to fat embolism syndrome. The intramedullary pressures generated with various intramedullary devices was determined and the effects of a fracture, with and without proximal and distal venting on these pressures were studied. Pressures generated in 78 embalmed anatomic specimen femurs and tibias were studied, leaving all soft tissues intact. Pressures were recorded for awl, guide rod, reamer, and nail insertion. Venting was done by creating a 4.5-mm hole in the cortex directly opposite the transducer. Proximal venting reduced proximal pressures to 80 mm Hg in the tibia (90% reduction) and 460 mm Hg in the femur (70% reduction). Distal venting reduced distal pressures to 65 mm and 30 mm in the tibias and femurs, respectively (90% reduction in pressures). Intramedullary pressures generated during nail or alignment rod insertion in anatomic specimen bone greatly exceeds the critical thresholds (150 mm Hg) thought to be responsible for fat emboli to the lung in the dogs. The introduction of a vent may reduce the chance of fat embolism. Despite the high association of raised intramedullary pressures and fat emboli in animal studies, there is no known critical threshold for humans. Therefore, although venting seems effective in reducing the intramedullary pressure in anatomic specimen bones, its efficacy in the patient with trauma remains to be determined.

Biomechanical Phenomena↗

PubMed1995

Some basic biomechanical characteristics of medullary pressure generation during reaming of the femur.

We measured femoral intramedullary pressures and applied axial thrust force generated in vitro during reaming with the AO and Zimmer systems. Six pairs of cadaver femora were instrumented with pressure taps midshaft and in the distal diaphysis, a load cell distally to measure force, and a displacement transducer to monitor reamer position. Following initial hand reaming, intramedullary power reaming was conducted utilizing a 9-mm reamer initially, with subsequent increases in steps of 0.5 mm. All femora were maintained at 37 degrees C and albumin was used to maintain a fluid-filled canal. The highest pressures consistently occurred during initial power reaming, with peak pressures ranging from 270 to 1500 mmHg amongst femora with the AO system. No significant differences were found in the peak pressures generated for the two systems (P = 0.10). The pressure measurements at the two locations in the femur were consistently similar, indicating that pressures are continuous throughout this aspect of the femur. The pressures were not correlated with instantaneous applied axial thrust (R2 = 0.191), and this could be attributed chiefly to the additional friction force of cutting. While pressure generation in the medullary canal upon reaming is likely governed by the rate of clearance of canal content, this is a highly variable response produced by characteristics of the femur which are still not fully understood.

Aged↗

PubMed1991

Biomechanical testing of new and old fixation devices for vertical shear fractures of the pelvis.

Malgaigne fractures of the pelvis have been treated with many different methods of fixation. We developed a plate for use on the anterior aspect of the sacroiliac (SI) joint using information obtained from cadaveric dissections and computed tomography (CT) scans of male (50) and female (50) pelvises. We tested each of six pelvises in the Instron, with five different fixation systems. Our results showed that the weakest system was the anterior quadrilateral frame plus two symphyseal plates. When comparing three posterior screws with the SI joint plate, the difference was not statistically significant. However, in both of these systems, a second symphyseal plate added to the overall stability.

Biomechanical Phenomena↗

PubMed1987

Anterior approach and stabilization of the disrupted sacroiliac joint.

Pelvic fractures with disruption of the important weight-bearing sacroiliac area can lead to impaired gait due to malunion or pelvic obliquity, back or buttock pain arising from the sacroiliac joint, and permanent neurologic damage. In eight patients with sacroiliac joint dislocation, an anterior retrofascial approach and stapling of the sacroiliac joint was performed. Six of these patients maintained an anatomic reduction of the sacroiliac joint and their results were rated as excellent. Two of the eight patients had a slight loss of reduction and because of intermittent mild pain were rated as having fair results. In another eight patients, plate fixation of the anterior sacroiliac joint was done. New stabilization methods utilizing dynamic compression plates, reconstruction plates, and a new four-hole plate have been developed to provide more secure fixation of these unstable injuries.

Adult↗

PubMed1987

Arthrodesis of the wrist.

In a retrospective study, the wrists of 18 patients who underwent arthrodesis by the AO technique were assessed clinically, for hand strength and function. Follow-up averaged 4 years (range from 1 to 7 years). Although wrist arthrodesis improved grip strength, it was still only 50% to 60% of normal. Hand function improved to within normal limits in 78% of patients and bony union occurred in 94.4%. Thirteen patients were back at work within 18 months. The AO technique of wrist arthrodesis allows correction of deformity, relief of pain, increased grip strength and improved hand function.

Arthrodesis↗

PubMed1986

Open versus closed intramedullary nailing of femoral shaft fractures.

A retrospective study was performed including only fractures involving the middle three fifths of the femoral shaft with a minimum of 2 years followup. There were 65 fractures in Group I treated with the closed technique utilizing the image intensifier. These were compared with 65 fractures treated with open reduction and nailing. Followup averaged 4 years (Group II). Group 1 had 92% satisfactory results; Group II achieved 97% satisfactory, not statistically significantly different. Our recommendations are delaying the procedure did not appear to be advantageous; excluding the fractures with segmental bicortical loss, there are limited indications for locked nails in these fractures; the decision to use a specific type of internal fixation should be based on the fracture pattern, the surgeon's experience, and the equipment available; if a closed technique is chosen, be prepared to open the fracture if a satisfactory closed reduction cannot be attained. This, in our study, did not increase the risk of reducing the functional result.

Adult↗

PubMed1986

Posterior sternoclavicular dislocations.

Twelve cases of posterior sternoclavicular dislocation were seen over 15 years at the Victoria General Hospital and the Izaak Walton Kiliam Hospital for Children in Halifax, NS. Two patients required open reduction of the dislocation but the rest were treated by closed reduction. One of the former group required threaded K wires for stability, but all other dislocations were deemed stable after reduction and application of a figure-of-eight bandage and an arm sling. There were no failures of reduction and no recurrent dislocations; the authors have been successful even in late closed reduction (up to 5 days) and therefore recommend it highly as the primary treatment. Open reduction is much more difficult and hazardous.

Adolescent↗