Michael J. Prayson

Biomechanical comparison of fixation methods in transverse olecranon fractures : A cadaveric study

OBJECTIVES/HYPOTHESIS Our null hypothesis was that no difference in fracture displacement would be detected between traditional monofilament wire and Kirschner wire placement versus three modified tension-band techniques for transverse olecranon fractures. STUDY DESIGN A nested form of the repeated measures design with twenty-two paired embalmed elbows (subjects grouped by sex and nested within the fracture method). METHODS Transverse osteotomies were created at the olecranon and stabilized with four techniques. One hundred cycles of loading were applied to achieve a peak flexion bending moment at the fracture of nine newton-meters. At the onset of testing, the triceps tendon was anchored at an initial elbow flexion angle of 70 degrees. RESULTS When using a monofilament figure-eight loop, oblique Kirschner wire placement into the anterior ulnar cortex provided greater resistance to tensile force than intramedullary Kirschner wires (p = 0.04). With intramedullary Kirschner wire placement, 1.6-millimeter-diameter braided cable in both figure-eight (p < 0.0001) and circular loop (p < 0.0001) designs allowed less fracture displacement than did the 1.0-millimeter-diameter monofilament wire. There was no difference between figure-eight and circular loop configurations when using braided cable (p = 0.98). CONCLUSIONS In transverse noncomminuted olecranon fractures, fixation with monofilament wire is superior with Kirschner wire placement into the anterior ulnar cortex. With intramedullary Kirschner wires, fixation using braided cable is significantly improved over that with monofilament wire. When using braided cable, figure-eight and circular loop designs allow similar displacements. Braided cable or anterior cortical Kirschner wire purchase increases the stability of fixation over that achieved with the traditional method.

Exchange reamed nailing for aseptic nonunion of the tibia.

BACKGROUND Exchange reamed nailing of the tibia is a common procedure in the treatment of an aseptic tibial nonunion. However, reports in the literature supporting this technique are limited. METHODS Forty patients with a tibial nonunion after initial unreamed intramedullary nailing were retrospectively assessed after an exchange reamed nailing. The main outcome measurements included radiographic and clinical union as well as time from exchange reamed nailing to union. RESULTS Thirty-eight patients achieved union of their fracture (95%). The average time from exchange nailing to union was 29 +/- 21 weeks. Complications included one deep vein thrombosis (2.5%) and two hardware failures (5%). CONCLUSION Exchange reamed nailing for nonunions of the tibia results in a high union rate and is associated with a low complication rate. This technique is recommended as a standard procedure for aseptic tibial nonunions after initial unreamed intramedullary nailing.

Biomechanical comparison of fixation methods in transverse patella fractures

OBJECTIVE To compare monofilament wire versus braided cable for stabilizing transverse patella fractures using the modified AO tension band technique. DESIGN A randomized blocked (paired) study comparing two fixation methods. Statistical analysis was performed using a nested repeated measures analysis, followed by Bonferroni post hoc testing. METHODS Seven paired embalmed knees (mean age 71.8 years, SD 14.6 years) were dissected, and transverse fractures were simulated. The knees were reduced and randomly fixed by either two parallel 0.062-inch Kirschner wires with a 1.0-millimeter-diameter 316L stainless steel monofilament wire tension loop or two Kirschner wires with a 1.0-millimeter-diameter 316L stainless steel braided cable tension loop. Knees were tested by applying a cyclic load through the suprapatellar tendon between twenty and 300 newtons for thirty cycles. RESULTS The maximum fracture displacement increased with each cycle of loading for both the braided cable and monofilament wire tension loop configurations (p = 0.0001). The average peak displacement at the thirtieth cycle was 2.25 millimeters for monofilament wire and 0.73 millimeters for the cable. When comparing both methods for all cycles, the braided cable allowed less fracture displacement than did the monofilament wire (p = 0.002), and the rate of increase per cycle of maximum fracture displacement was less for the cable than for the wire (p = 0.0001). CONCLUSIONS In transverse, noncomminuted patella fractures, fixation with two Kirschner wires and a 1.0-millimeter braided cable tension loop was superior to the monofilament wire tension loop. Most importantly, the braided cable afforded more predictable results during cyclic loading.

Mechanical Comparison of Endosteal Substitution and Lateral Plate Fixation in Supracondylar Fractures of the Femur

Objective To assess for improved rigidity with the addition of a medial endosteal plate to laterally plated supracondylar femoral fractures. Design A randomized paired study in a supracondylar femoral fracture model comparing two fixation methods tested cyclically in axial and torsional loading. Methods One-centimeter supracondylar gap osteotomies were created in twenty synthetic femurs approximately six centimeters proximal to the knee joint. Ten were stabilized with a lateral eight-hole buttress plate alone, and ten were secured by a similar lateral buttress plate plus a medial endosteal eight-hole dynamic compression plate. Group 1 (n = 5; lateral plate alone) and Group 2 (n = 5; lateral and endosteal plates) were axially loaded up to 700 newtons through a materials test system for three cycles. A displacement transducer detected movement at the medial fracture gap. Group 3 (n = 5; lateral plate alone) and Group 4 (n = 5; lateral and endosteal plates) were tested in torsion. A rod-and-pulley system created an external rotation torque up to twenty Newton-meters for three cycles. A rotary potentiometer measured angular displacement. Results Lateral buttress plating with endosteal substitution showed statistically significant decreased motion at the fracture site in torsional (p < 0.004) and axial loading (p < 0.0001) versus lateral buttress plating alone using Students t test. Conclusion The addition of a 4.5-millimeter endosteal plate to a lateral buttress plate provides significantly increased stability, as compared with lateral plating alone in a femoral supracondylar fracture model during simulated axial and torsional loading. Neither fixation construct, however, restored the torsional stability of the distal femur to its preinjury (intact) level.

Use of the Reamer-Irrigator-Aspirator for Bone Graft Harvest: A Mechanical Comparison of Three Starting Points in Cadaveric Femurs

Objectives: The mechanical behavior of cadaveric femurs after intramedullary reaming using the Reamer-Irrigator-Aspirator (RIA) for autogenous bone graft harvest has not been fully described. We hypothesized that reamed femurs, regardless of starting point, would adequately withstand cyclic loading simulating postoperative single-leg stance. Methods: Twenty-one cadaveric pairs were randomly assigned to one of three groups based on starting point: Group 1 (trochanteric), Group 2 (piriformis fossa), and Group 3 (retrograde). Each femur underwent dual-energy x-ray absorptiometry scanning and radiographs. Each test femur was reamed to 15 mm using the RIA with the contralateral femur serving as the control. The specimens were loaded to 1400 N of axial compression with 2° simultaneous torsion for 10,000 cycles. If the femur survived cyclic loading, it was then loaded to failure in axial compression. Comparisons regarding survival of cyclic loading were made using Fisher exact test. Results: No differences were seen between groups regarding age, sex, and T-score. The mean T-score for the femurs was -2.531 ± 1.372. Overall, 18 of 21 (86%) test femurs and 20 of 21 (95%) control femurs withstood cyclic loading (P = 0.606). Statistical significance was not reached for the three pairwise comparisons between test groups. The femurs failed in patterns consistent with simple pertrochanteric, basicervical, midcervical, or subcapital fractures. Conclusions: Intramedullary reaming for bone graft harvest using the RIA without subsequent intramedullary stabilization did not significantly degrade the mechanical behavior of cadaveric femurs in simulated single-leg stance regardless of reamer starting point. It appears safe to allow single-leg stance weightbearing on a reamed, unstabilized femur after bone graft harvesting using the RIA.

Does open reduction increase the chance of infection during intramedullary nailing of closed tibial shaft fractures

Objective To evaluate whether an open technique used to obtain reduction during intramedullary nailing of closed tibial shaft fractures increases the risk of infection, compared to closed reduction and nailing. Setting University level 1 trauma center. Design Retrospective database analysis. Patients/Participants One hundred seventeen patients with 119 fractures from our trauma database who had sufficient follow-up and met study criteria. The patients were grouped by open versus closed reduction. Only OTA fracture types 42 A to C were included in this study. Intervention Locked reamed intramedullary nailing for closed tibial shaft fractures accomplished through either open or closed reduction. Main Outcome Measurement The presence or absence of infection as determined by the clinical presentation (erythema, warmth, purulent drainage, fevers, chills, increased pain at the fracture site), indicative laboratory work (complete blood count, erythrocyte sedimentation rate, C-reactive protein), and/or positive culture. Results There were 85 males and 32 females. The average age was 35.7 years; the average follow-up was 14.3 months. Of the 119 fractures, 79 had closed reduction whereas 40 had open reduction. The open reductions consisted of 13 with a formal incision (>1 cm in length), 22 with percutaneous incisions, and 5 with fasciotomies. There were no infections in the closed reduction group and 2 infections (5%) in the open reduction group. This difference was not statistically significant (P=0.1). The average time to union was 7.0 months in closed reductions and 7.3 months in open reductions. By latest follow-up, 107 fractures had reached union (89.9%), 1 had not (0.8%), and 11 were lost to final follow-up (9.2%). Conclusions Limited open techniques can greatly facilitate the reduction of closed tibial shaft fractures but raise concern for infection through exposure of the fracture site. This study found that the rate of infection for open versus closed reductions was higher but not statistically different. Judicious use of open reduction techniques during intramedullary nailing of closed tibia fractures seems to have a minimal risk of infection.

Adherence to Preoperative Cardiac Clearance Guidelines in Hip Fracture Patients.

Objectives: To identify if preoperative cardiac consultations are made in accordance with the American College of Cardiology (ACC) Foundation and American Heart Association (AHA) guidelines and the delays in care after unnecessary consults. Design: Retrospective review. Setting: Level 1 trauma center. Patients/Participants: A retrospective review of 315 patients with hip fractures admitted over a 2-year period was conducted. After excluding patients younger than 65 years and those admitted by the general surgery trauma service, 266 patients were included. Intervention: Criteria meeting the ACC/AHA guidelines for preoperative cardiac consultations. Main Outcome Measurements: Time to surgical intervention and total hospital length of stay. Results: Of the 266 patients reviewed, 55 patients (21%) received preoperative cardiac consultations, whereas 211 patients did not. Only 16 of the 55 patients (29%) with cardiac consults met the ACC/AHA guidelines, whereas 39 patients received unnecessary cardiac consults. Of the 247 patients (39 with consults and 208 without consults) who did not meet the guidelines, those who received a preoperative cardiac consult had a significantly longer average time to surgery (43.9 vs. 23.1 hours) (P = 0.005) and hospital length of stay (7.9 vs. 5.3 days) (P = 0.010). There were no significant differences in postoperative complications or disposition. Conclusions: Preoperative cardiac consults are frequently overused and lead to delays to surgical intervention and longer hospital length of stay while not revealing any further need for cardiac intervention or changing the rate of adverse events. Stricter adherence to the ACC/AHA guidelines will help decrease surgical delay and hospital length of stay. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Bilateral sacroiliac joint dislocation without associated fracture or anterior pelvic ring injuries.

Summary: SI joint dislocations are serious injuries. They are often associated with posterior fractures or anterior ring disruptions. This case report documents the outcome of a patient with an uncommon injury involving bilateral SI joint dislocation without associated anterior pelvic injuries or posterior pelvic fracture.

External Fixation of the Pelvis

Summary The approach to pelvic fractures has undergone substantial change throughout the years. Considerable controversy exists concerning this fracture in terms of hemorrhage etiologies, treatment options, complications, and outcomes. External fixation became popular when conservative treatment was found to be less successful than previously thought. Although there is a trend away from external fixation as internal fixation continues to emerge, external fixation has a definite role in pelvic fracture management. The authors review the indications and techniques for external fixation in the management of pelvic fractures.

The effects of magnetic resonance imaging on surgical staples: an experimental analysis.

BACKGROUND Surgical staples are commonplace in repairing surgical incisions. Staples allow for expeditious closure and removal compared with suture materials. However, there are clinical concerns when obtaining a magnetic resonance imaging (MRI) scan with staples present. This study examined two issues related to MRI scanning in the presence of surgical staples: skin surface temperature change and staple displacement. METHODS Thirty pig feet had 3-cm surgical incisions repaired with five surgical staples. Once placed, each skin staple position was marked for later referencing. A surface temperature laser device recorded prescan skin surface temperature. A 35-minute MRI scan was performed with a 1.5-Tesla magnet and standard knee coil for each pig foot. Immediately afterward, the skin surface temperature and displacement measurements were recorded. The paired t test was used to analyze temperature change from prescan to postscan. RESULTS The prescan mean temperature was 16.45°C (standard deviation: 0.70°C), and the range was 14.60°C to 18.20°C. After scanning, the mean temperature was 16.02°C (standard deviation: 0.63°C), and the range was 15.00°C to 17.60°C. The decrease of 0.43°C in skin surface temperature was statistically significant (p=0.001). No change in staple position was measurable or evident by visual inspection for any of the pig feet. CONCLUSION This study found no increase in skin surface temperature or displacement of staple position after a standard extremity MRI scan. Based on our findings, MRI scanning in the presence of stainless steel surgical staples seems safe.