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Dean G Lorich

Publications and source records attributed to Dean G Lorich.

At least 19 recordsLinked to original sources
PubMed2006

An evaluation of accuracy and repeatability of a novel gait analysis device.

INTRODUCTION: Restoration of gait is a particularly important patient-based functional outcome following lower extremity trauma. A new portable device which measures gait parameters, the IDEEA, may be particularly useful in evaluating post-traumatic gait parameters in the office setting, but the accuracy and repeatability of this device relative to standard gait laboratory footswitches are unknown. MATERIAL AND METHODS: Twelve healthy subjects were tested simultaneously using the IDEEA device and standard gait laboratory footswitches, at slow, medium, and fast speeds. Parameters evaluated were single-limb support time (SLS), double-limb support time (DLS), swing phase duration (SPD), cycle duration, and cadence. RESULTS: The repeatability between right and left measurements tended to be better for the IDEEA, and was at least as good as the foot switches. The absolute differences of the timed gait parameters between the two devices were all in the range of 0.03 s, which is within the data sampling resolution of the gait laboratory foot switches (0.04 s). Furthermore, assuming a 1-s gait cycle, these differences account for only 3% of the gait cycle, which is also well within the clinical parameters for evaluating and differentiating between treatments. CONCLUSION: This device is accurate and repeatable, and may facilitate the evaluation of gait function in post-traumatic patients in settings outside of the traditional gait laboratory.

Adult↗
PubMed2006

The ability of the Lauge-Hansen classification to predict ligament injury and mechanism in ankle fractures: an MRI study.

OBJECTIVES: The Lauge-Hansen classification system was designed to predict the mechanism and ligament injury patterns of ankle fractures on the basis of x-rays. The purpose of this study was to evaluate the accuracy of these predicted injury sequences using magnetic resonance imaging (MRI) in a series of patients with ankle fractures. DESIGN: Retrospective cohort. SETTING: Two university level 1 trauma centers. PATIENTS: Fifty-nine patients with operative ankle fractures who were evaluated with both x-ray and MRI were included. INTERVENTION: All patients had a standard 3-view ankle x-ray series before fracture reduction, followed by an MRI. All plain x-rays were assigned to a Lauge-Hansen category by an experienced orthopedic traumatologist. MRI studies were subsequently read by an MRI musculoskeletal radiologist for the integrity of the ankle ligaments. MAIN OUTCOME MEASUREMENTS: After evaluation of the x-rays, fractures were classified according to the system of Lauge-Hansen, and the predicted presence, sequence, and mechanism of injury was determined. These were then compared to the actual injured structures on MRI in each case, and the ability of the Lauge-Hansen system to accurately predict the complete injury pattern was determined for the entire cohort. RESULTS: Average patient age was 59 (range: 18 to 84) years. Of the 59 ankle fractures evaluated, 37 (63%) were classified as supination external rotation, 11 (19%) were pronation external rotation, 1 (2%) was supination adduction, and 10 (17%) were not classifiable on the basis of the Lauge-Hansen system. Of the 49 fractures that fit into Lauge-Hansen categories, 26 (53%) had patterns of ligamentous injury and fracture morphology that did not coincide with the Lauge-Hansen predictions. A common fracture pattern was observed in 8 of the 10 unclassifiable fractures, which included a high spiral fracture of the fibula, vertical shear fracture of the medial malleolus, posterior malleolar fracture, and complete tears of the anterior-inferior tibiofibular ligament and the interosseous membrane. In addition, over 65% of patients in this series had complete ligamentous injury and a fracture of the malleolus to which the ligament attaches. CONCLUSIONS: These results demonstrate that the Lauge-Hansen classification system may have some limitations as a predictor of the mechanism of injury and the presence of soft-tissue damage associated with ankle fractures. The identification of a novel pattern of ankle fracture also illustrates how the system fails to describe all possible fracture patterns. For these reasons, we recommend that the Lauge-Hansen system be used only as a guide in the diagnosis and management of ankle fractures and not solely relied upon for treatment decisions. Although the exact clinical implications of the variety of ligamentous injuries observed on MRI are yet to be determined, this technique may be useful in individual cases in which doubt about joint stability and soft-tissue integrity exists. Additionally, MRI may be helpful in planning surgical approaches in atypical fractures in which injury patterns are less predictable solely on the basis of x-ray.

Adolescent↗
PubMed2006

Intramedullary fixation of tibial shaft fractures using an expandable nail: early results of 54 acute tibial shaft fractures.

OBJECTIVE: To evaluate and present our experience using the expandable nail system for the treatment of acute tibial shaft fractures. DESIGN: Retrospective study. SETTING: Two level-1 trauma centers-University teaching hospitals. METHODS: Fifty-four consecutive patients were treated by this nail system for acute tibial shaft fracture. Two nail diameters were used, 8.5 mm and 10 mm. Operation, hospitalization and healing times, reaming versus nonreaming, isolated versus multiple injuries, and reoperations were recorded and analyzed statistically. RESULTS: Follow-up was obtained either until fracture healing or for a minimum of 1 year with an average of 14 months (12 to 24). All fractures healed in an average time of 72 days (21 to 204). The average healing times for patients treated with 8.5-mm and 10-mm nails were 77.2 days (27 to 204) and 63.4 days (21 to 121), respectively. Average operative time was 103 minutes (40 to 185) if reamed and 56 minutes (30 to 80) if unreamed. Average healing times were 65.4 days (21 to 190) if reamed and 79.5 days (42 to 204) if unreamed. There were 11 complications (20.4%) related to the nailing: 3 deep infections, 2 superficial infections, 2 bone shortenings of 1 cm secondary to nail protrusion in the knee, 1 compartment syndrome, 1 fracture propagation, 1 distal malalignment, and 1 delayed union. Hardware was removed in 6 patients (3 infections, 2 patients' request and 1 protrusion into the knee), and 1 additional patient underwent exchange nailing due to a delayed union. CONCLUSIONS: The expandable nail offers the theoretical advantages of improved load sharing and rotational control without the need for interlocking screws. This study demonstrates satisfactory healing and alignment for the treatment of tibial shaft fractures using this device. However, caution must be exercised when using this nail in cases of significant comminution and in cases where the fracture pattern involves the more proximal or distal aspect of the tibial shaft.

Adult↗
PubMed2006

Fixation of posterior malleolar fractures provides greater syndesmotic stability.

Syndesmotic injuries are common in ankle fractures. Traditional syndesmosis fixation may be associated with a secondary procedure. When the posterior malleolus is fractured, the posterior syndesmotic ligaments may remain intact and attached to the fragment. Our goals were to establish the incidence of syndesmotic ligament ruptures in pronation-external rotation type ankle injuries associated with posterior malleolar fractures, and to assess syndesmotic stability after fixation of the posterior malleolus compared with using a syndesmotic screw. Fifteen patients who sustained pronation-external rotation Stage 4 ankle fractures that involved the posterior malleolus were evaluated using radiographs and magnetic resonance imaging. No complete tears of the posterior-inferior tibiofibular ligament occurred. A pronation-external rotation fracture pattern with a posterior malleolar fragment was created in 10 lower extremity cadaver specimens with random fixation of the posterior malleolus or the syndesmosis. Compared with the intact specimens, stiffness was restored to 70% after fixation of the posterior malleolus, and to 40% after syndesmosis stabilization. Syndesmotic stability may be obtained more effectively by fixation of the posterior malleolus rather than by using a syndesmotic screw. Although additional clinical investigation is warranted, these concepts may be useful in eliminating syndesmotic screw fixation in select patients.

Adult↗
PubMed2006

Vascular implications of minimally invasive plating of proximal humerus fractures.

OBJECTIVES: Open reduction and internal fixation of proximal humerus fractures through the anterolateral acromial approach, which uses the anterior deltoid raphe and axillary nerve protection, has recently been advocated as a minimally invasive technique. Several recent reports have indicated variable and unpredictable vascular injuries to the humeral-head blood supply after a proximal humerus fracture, and thus a direct approach that minimizes further vascular compromise may be preferable. The purpose of this study was to define the relationship of this surgical interval to the lateral plating zone of the proximal humerus and to the penetrating vascular supply of the humeral head. DESIGN: Cadaveric vascular injection study. SETTING: Cadaveric dissection laboratory. PATIENTS: Six cadaveric specimens. INTERVENTION: The anterolateral acromial approach was performed on six cadaveric upper-extremity specimens. A locking proximal humerus plate was applied to the lateral proximal humerus, and the axillary artery was cannulated proximal to the circumflex humeral arteries. Dyed latex polymer was injected and allowed to harden, and dissection was performed to visualize the vasculature of the proximal humerus. Plates were then removed and the specimens were further inspected to examine the blood supply. MAIN OUTCOME MEASUREMENTS: The relationship of the anterolateral acromial approach to the lateral plating zone of the proximal humerus and the vascular supply of the humeral head. RESULTS: In all specimens, the filling of the anterior and posterior vessels that supplied the humeral head were undisturbed after use of the anterolateral acromial approach and locked plating. The blood vessels to the head-penetrating vascular branches were not in the surgical field. A bare spot on the lateral proximal humerus existed in the region of the greater tuberosity, which was 30 mm wide and between two penetrating humeral-head epiphyseal vessels. The nearest penetrating vessels were close to the plate, 4 mm anterior and 7 mm posterior. The anterior humeral circumflex vessel and its ascending branch, which provides critical blood supply to the humeral head, coursed directly in the region of the deltopectoral approach. CONCLUSIONS: Minimally invasive techniques have many potential benefits for fracture healing, but new surgical approaches often must be used to take full advantage of these newer methods. Splitting the anterior deltoid raphe from the acromion distally allowed direct access to the lateral plating zone of the proximal humerus. The bare spot in this region may be a safe area for plate application, if the plate is placed appropriately with thorough knowledge of the vascular anatomy. These findings may be of particular importance if the vascular supply to the humeral head has already been partially compromised by preceding trauma. This direct approach to the lateral bare spot on the proximal humerus may minimize iatrogenic vascular injury when treating these fractures.

Aged↗
PubMed2006

Prediction of soft-tissue injuries in Schatzker II tibial plateau fractures based on measurements of plain radiographs.

BACKGROUND: Split-depression fractures of the lateral tibial plateau (Schatzker II) are associated with a significant risk of capsuloligamentous and meniscal injury. We hypothesized that the amount of fracture depression and widening on anteroposterior (AP) plain radiographs would correlate with the incidence of injury to these structures on magnetic resonance imaging (MRI). METHODS: Sixty-two consecutive patients with Schatzker II tibial plateau fractures had a knee x-ray series and MRI preoperatively. AP plain radiographs were measured for lateral joint line depression and condylar widening, and MRIs were evaluated for injury to soft-tissue structures around the knee. For each structure, the threshold of depression and widening that led to the greatest disparity in soft-tissue injury was determined. Multiple logistic regressions were applied to calculate whether depression and/or widening above the thresholds were predictive for injury to individual soft-tissue structures. RESULTS: When depression was greater than 6 mm and widening was greater than 5 mm, lateral meniscal injury occurred in 83% of fractures, compared with 50% of fractures with less displacement (p < 0.05). When either depression or widening was at least 8 mm, medial meniscal injury occurred more frequently (depression 53%, p < 0.05; widening 78%, p < 0.05; versus neither 15%). Lateral collateral ligament and posterior cruciate ligament tears were not seen with minimally displaced fractures (< 4 mm), but the incidence of injury approached 30% with increasing displacement. CONCLUSIONS: Due to the limited availability of MRI in some centers, correlation of lateral condylar depression and widening, as measured on plain radiographs, to injury of various soft-tissue structures may be extremely helpful in planning open or arthroscopic treatment methods. Using these guidelines, Schatzker II fractures with depression or widening approaching 5 mm deserve heightened vigilance in diagnosing and treating these concomitant soft-tissue injuries.

Adolescent↗
PubMed2006

Malreduction of the tibiofibular syndesmosis in ankle fractures.

BACKGROUND: Diagnosis and reduction of syndesmosis injuries in ankle fractures can be challenging. Previous studies have demonstrated that standard radiographic measurements used to evaluate the integrity of the syndesmosis are inaccurate. The purpose of this study was to determine the adequacy of standard postoperative radiographic measurements in assessing syndesmotic reduction compared to CT and to determine the prevalence of postoperative syndesmotic malreduction in a patient cohort. METHODS: Twenty-five patients with ankle fractures and syndesmotic instability who had open reduction and syndesmotic fixation were evaluated. All patients had a standard radiographic series postoperatively followed by a CT scan. Radiographic measurements were made by three observers to determine the tibiofibular relationship. Axial CT scan images were judged for quality of reduction of the syndesmosis by measuring the distance between the fibula and the anterior and posterior facets of the incisura. Differences between the anterior and posterior measurements of more than 2 mm were considered incongruous. RESULTS: Six patients (24%) had evidence of postoperative diastasis using the radiographic criteria, four of whom had evidence of malreduction on postoperative CT scan. Conversely, 13 patients (52%) had incongruity of the fibula within the incisura on CT scan (average 3.6 mm, range 2.0 to 8.0 mm), only four of whom had one or more abnormal radiographic measurements. In 10 (77%) of the 13 malreductions seen on CT scan, the posterior measurement was greater, indicating that internal rotation or anterior translation of the fibula may have occurred. Sensitivity of radiographs was 31% and the specificity was 83% compared to CT. CONCLUSIONS: Many syndesmoses were malreduced on CT scan but went undetected by plain radiographs. Radiographic measurements did not accurately reflect the status of the distal tibiofibular joint in this series of ankle fractures. Furthermore, postreduction radiographic measurements were inaccurate for assessing the quality of the reduction. Although we did not seek to correlate functional outcomes, the known morbidity of postoperative syndesmotic malreduction should lead to heightened vigilance for assessing accurate syndesmosis reduction intraoperatively.

Adolescent↗
PubMed2006

Hybrid locked plating of osteoporotic fractures of the humerus.

BACKGROUND: Locked plating techniques recently have gained popularity and offer a different biomechanical approach for fracture fixation compared with traditional compression plating. In certain clinical situations, it may be preferable to employ a "hybrid" construct, in which an unlocked screw is used to assist with reduction and locked screws are subsequently used to protect the initial reduction. In the present study, we used an unstable osteoporotic fracture model of the humerus to determine (1) whether a hybrid construct behaved more like a locked construct or a conventional unlocked construct and (2) whether there was a difference between locked and unlocked constructs. METHODS: Thirty third-generation Sawbones humeri were divided into three groups of ten humeri each. A locking plate with combination holes was applied to each bone with use of either a locked construct, an unlocked construct, or a hybrid construct. To simulate purchase in osteoporotic bone, all screw-holes were drilled to 0.3 mm less than the diameter of the screw used. Each specimen was then osteotomized in the middle part of the shaft, and a 5-mm segment was removed. Oscillating cyclic torsion testing was performed to +/-10 N-m for 1000 cycles, torsional stiffness was determined at periodic cyclic intervals, and the groups were compared. RESULTS: The locked and hybrid constructs demonstrated similar behavior. The initial stiffness was similar in these two groups. At ten cycles, the locked and hybrid constructs retained 96.3% and 95.4% of their initial stiffness, respectively. During the remainder of cycling the stiffness of the locked and hybrid constructs decreased in a linear fashion (R(2) = 0.89 and 0.88, respectively), and at 1000 cycles the stiffness of the locked and hybrid constructs averaged 80.0% and 79.2% of the initial values, respectively (p = 1.0). In contrast, the unlocked constructs initially were significantly less stiff than both the locked and hybrid constructs (p < 0.001). At ten cycles the unlocked constructs retained 80.4% of their initial stiffness, and at 1000 cycles they retained only 22.3% of their initial stiffness. CONCLUSIONS: Hybrid constructs are mechanically similar to locked constructs, and both are significantly more stable than unlocked constructs under torsional cyclic loading. CLINICAL RELEVANCE: Combining screws in the hybrid configuration used in the present study did not compromise the mechanical performance of the construct. Hybrid constructs may decrease cost and may provide additional clinical value when treating fractures in osteoporotic bone.

Bone Plates↗
PubMed2005

Early changes in prostaglandins precede bone formation in a rabbit model of heterotopic ossification.

We have tested the hypothesis that the formation of heterotopic ossification (HO) in a rabbit model is correlated with a local increase in specific prostaglandins that may modulate mechanisms of ossification. Rabbits were sacrificed at 1 to 21 days following the daily forcible flexion of immobilized knees. The extraction and analysis of prostaglandins (PG) E2, F2alpha, D2, 6-keto-F1alpha, and thromboxane B2 in vastus intermedius muscles of manipulated legs revealed increases compared to control hindlimbs for all five prostaglandins, albeit of differing magnitude. The earliest increase was observed for PGF2alpha after 24 h (to 2.6-fold of control) with peak levels observed at day ten (185-fold of control). PGE2 was increased above control from 2 to 21 days following manipulation, with a peak level of 33-fold of control after 10 days. In a separate arm of the study, the role of PGE2 was investigated through the use of pharmacological antagonist of the PGE2 receptors and one of its second messengers, cAMP. Rabbits were preadministered the PGE2/PGD receptor antagonist AH 6809 or the cAMP antagonist Rp-cAMP prior to undergoing the regimen of limb immobilization and passive exercise. Both AH 6809 and Rp-cAMP were found to prevent the later development of radiographically documented heterotopic ossification in 15 out of 16 animals, thus identifying prostaglandins as being required for the development of ectopic bone. In this latter group, all but one pharmacologically treated animal showed an absence of HO at 3, 4, 5, or 6 weeks. These findings suggest an obligate cascade of prostaglandins for HO that offers the potential for novel prophylactic therapies, including those that target receptors for specific prostaglandins.

Animals↗
PubMed2005

Helical plating of the proximal humerus.

The ideal treatment for fractures of the proximal humerus has not been definitively agreed upon. Several recent reports have described a technique of helical plating for proximal humeral fractures, in which the proximal plate is placed laterally on the greater tuberosity, and spirals 90 degrees distally to lie on the anterior surface of the humeral shaft. The purpose of this study was to evaluate the feasibility of helical plating using a less invasive surgical approach and placing screws percutaneously in the distal plate. Dissection of 10 cadaveric upper extremity specimens was performed, using an extended anterolateral acromial approach followed by percutaneous helical plating. With the plate secured, the neurovascular structures which crossed the anterior humerus superficial to the plate were exposed and identified. Only the musculocutaneous nerve crossed anterior to the plate and was at risk for percutaneous screw placement. The nerve location was found in a consistent location among the specimens. The danger zone for the nerve location was found to be at an average of 13.5 cm from the greater tuberosity (99% CI: 12.2-14.8 cm). Though clinical experience is necessary to validate this plating technique, it appears that avoiding this danger zone in which the musculocutaneous nerve crosses will allow safe percutaneous screw placement and permit minimally invasive plating of these fractures.

Aged↗
PubMed2005

The incidence of soft tissue injury in operative tibial plateau fractures: a magnetic resonance imaging analysis of 103 patients.

OBJECTIVES: The goal of this study was to determine the incidence of injury to soft tissue structures of the knee in tibial plateau fractures scheduled for surgery. DESIGN: Prospective cohort. SETTING: Level I academic medical center. PATIENTS/PARTICIPANTS: One hundred three consecutive patients with acute tibial plateau fractures indicated for operative intervention. INTERVENTION: Standard x-ray examinations, including anteroposterior, lateral, and oblique views, were performed in the emergency department. Subsequently all patients had magnetic resonance imaging performed. The Schatzker and AO/OTA classifications were used to classify each fracture pattern based solely on the x-rays. Soft tissue injuries were assessed by magnetic resonance imaging. MAIN OUTCOME MEASUREMENTS: Fifteen categories of injury were determined as positive or negative on each magnetic resonance imaging, which included tears of the cruciates, collateral ligaments, menisci, and posterolateral corner. RESULTS: The overall incidence of injury to soft tissues was higher than previously reported. Only 1 patient (1%) in the series had complete absence of any soft tissue injury. Seventy-nine patients (77%) sustained a complete tear or avulsion of 1 or more cruciate or collateral ligaments. Ninety-four patients (91%) had evidence of lateral meniscus pathology. Forty-five patients (44%) had medial meniscus tears. Seventy patients (68%) had tears of 1 or more of the posterolateral corner structures of the knee. The most frequent fracture pattern was a lateral plateau split-depression (Schatzker II) (60%). No pure depression injuries (Schatzker III, AO/OTA 41-B2) were seen. CONCLUSIONS: The incidence of complete ligamentous or meniscal disruption associated with operative tibial plateau fractures was higher than previously reported. Though the clinical importance of injury to each of these structures is unknown, the treating surgeon should be aware that a variety of soft tissue injuries are common in these fractures. In addition, all fractures had at least 1 cortical split visible on magnetic resonance imaging, implying that pure depression patterns are very rare or may not exist.

Adolescent↗
PubMed2005

Complete exposure of the articular surface for fixation of patellar fractures.

Anterior tension band fixation constructs are among the mainstay of treatment of patella fractures and lead to reliable results with simple transverse fracture patterns. However, comminuted fractures of the patella require much more extensive articular reconstruction than interdigitating two large fragments to achieve a good result. In this report, we describe a technique for exposure, reduction, and stabilization of patella fractures that allows for direct visual reduction of the articular surface. Subsequent devices are applied directly to the bony surfaces of the patella without soft-tissue interposition, which distinguishes it from traditional approaches. This technique may be used to ensure articular surface congruity in simple transverse fractures and may be particularly useful in comminuted fractures when patellar excision would otherwise be considered.

Adult↗
PubMed2005

The extended anterolateral acromial approach allows minimally invasive access to the proximal humerus.

Lateral approaches to the proximal humerus have been limited by the position of the axillary nerve. Extensive surgical dissection through a deltopectoral approach may further damage the remaining tenuous blood supply in comminuted fractures. The purpose of our study was to explore a direct anterolateral, less invasive approach to the proximal humerus. Twenty cadaver shoulders were dissected using the extended anterolateral acromial approach through the anterior deltoid raphe. Multiple parameters were measured regarding the axillary nerve. The nerve was easily palpable in all specimens as it exited the quadrilateral space, and predictably was found and protected deep to the raphe, approximately 35 mm from the prominence of the greater tuberosity. Examination of the entire anterior nerve revealed that no branches besides the main motor trunk crossed the deltoid raphe. Subsequently, this approach was used in 16 patients with proximal humerus fractures, none of whom has had complications related to the surgical approach. This minimally invasive surgical approach seems to be safe, and may be useful in treating proximal humerus fractures.

Acromion↗
PubMed2005

Radiographic measurements do not predict syndesmotic injury in ankle fractures: an MRI study.

UNLABELLED: Several radiographic measurements have been described and are used to determine ligamentous injury in ankle fractures, particularly of the deltoid and syndesmosis complex. Because the accuracy of these radiographic measurements has been questioned, we sought to evaluate their accuracy using magnetic resonance imaging as an indicator for injury. Seventy patients with closed ankle fractures were entered prospectively into the study, and all had standard plain radiographic evaluations before reduction (anteroposterior, lateral, and mortise) and magnetic resonance imaging. Four radiographic measurements were made on initial ankle injury films: tibiofibular clear space on the anteroposterior view, tibiofibular overlap on the anteroposterior and mortise views, and medial clear space on the mortise view. These radiographic measurements and their association with magnetic resonance imaging findings then were analyzed. A medial clear space measurement greater than 4 mm correlated with disruption of the deltoid and the tibiofibular ligaments. We found no association between the tibiofibular clear space and overlap measurements on radiographs with syndesmotic injury on magnetic resonance imaging scans. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Ankle Injuries↗
PubMed2005

Periprosthetic patellar fracture after an open knee dislocation.

We present a patient who sustained an open knee dislocation with a periprosthetic fracture of the patella and who was treated satisfactorily with tension band wiring and a conservative rehabilitation program. In addition to describing this unique combination of injuries, we review the literature on the treatment of periprosthetic patellar fractures. Although internal fixation of these fractures historically has provided unpredictable results, we think that it is warranted if the patella has adequate bone stock.

Bone Wires↗
PubMed2005

The mechanical behavior of locking compression plates compared with dynamic compression plates in a cadaver radius model.

OBJECTIVE: The purpose of this cadaveric study was to compare the mechanical behavior of a locked compression plate, which uses threaded screw heads to create a fixed angle construct, with a dynamic compression plate construct in a cadaver radius model. DESIGN: Mechanical study with cyclic testing and high-speed optical motion analysis. SETTING: Biomechanics laboratory at an academic institution. PATIENTS/PARTICIPANTS: Eighteen pairs of fresh-frozen human cadaver radii were divided into 3 groups of 6 to be tested as a group in each of the following force applications: anteroposterior (AP) bending, mediolateral bending, or torsion. INTERVENTION: Each bone was osteotomized leaving a 5-mm fracture gap and then fixed with a plate. For each pair, 1 radius received a standard plate (limited-contact dynamic compression plates; LC-DCP), the contralateral radius was fixed with a locking compression plate (LCP), and specimens underwent cyclic loading. Normalized stiffness, average energy absorbed, and Newton-cycles to failure were calculated. In addition, a 3-dimensional, high-speed, infrared motion analysis system was used to evaluate motion at the fracture site. MAIN OUTCOME MEASUREMENTS: Construct stiffness, fracture site motion, cycles to failure, and energy absorption. Repeated measures ANOVA were used to detect differences between groups with time. RESULTS: In the torsion group, LCP specimens failed at 60% greater Newton-cycles than the LC-DCP (1473 vs. 918; P < 0.05). In the AP group, the LC-DCP absorbed significantly greater energy during 10,000 cycles compared with the LCP group (P < 0.05). The 2 constructs demonstrated different biomechanical behavior with time. As cycling progressed in the LC-DCP specimens under torsion testing, stiffness (measured at the actuator at the bone ends) did not change significantly; however, fracture motion (measured at the fracture surfaces) decreased significantly (P = 0.04). The LCP specimens did not display similar behavior. CONCLUSIONS: Our findings indicated that LCP constructs may demonstrate subtle mechanical superiority compared with the LC-DCP. The LCP specimens had less energy absorption in the AP group and survived longer in the torsion group. Discordance of motion between measurement regions was observed only in the LC-DCP torsion group, and may have been caused by plate-bone slippage or bone-screw subcatastrophic failure. However, many other compared parameters were found to be similar, and the clinical significance of the few differences found between constructs mandates further investigation.

Biomechanical Phenomena↗
PubMed2004

Correlation of interosseous membrane tears to the level of the fibular fracture.

OBJECTIVES: To correlate interosseous membrane (IOM) tears of the ankle to the height of fibular fractures in operative ankle fractures. DESIGN: Prospective clinical trial. SETTING: University Level 1 trauma center. PATIENTS: All patients admitted with a closed operative ankle fracture were included. Of 93 patients originally evaluated, 73 patients had adequate MRI for evaluation. INTERVENTION: Open reduction and internal fixation of each ankle fracture was performed after preoperative MRI evaluation of the IOM. Transsyndesmotic screw fixation was performed when evidence of syndesmotic instability was shown by intraoperative stress testing. MAIN OUTCOME MEASUREMENTS: Radiographs were analyzed for fracture classification and prediction of ligamentous injuries about the ankle. MRI evaluated the IOM integrity, correlating it to the height of the fibular fracture. RESULTS: Of the 73 ankle fractures with adequate MRI evaluation, 30 had identifiable complete IOM tears on MRI. Ten of the 30 IOM tears did not correlate with the level of the fractured fibula. Seven cases had IOM tears proximal to the fibular fracture as detected by MRI. Five of these cases were Weber B type fractures, and two were Weber C type fracture patterns. Conversely, three cases of Weber C type fractures had IOM tears that remained distal to the level of the fibular fracture. CONCLUSIONS: The level of the fibular fracture does not correlate reliably with the integrity or extent of the interosseous membrane tears identified on MRI in operative ankle fractures. One cannot consistently estimate the integrity of the IOM and subsequent need for transsyndesmotic fixation based solely on the level of the fibular fracture. An intraoperative syndesmotic stress test is recommended to establish the presence or absence of syndesmotic instability.

Adolescent↗