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Biomedical subjects

David L Helfet

Publications and source records attributed to David L Helfet.

At least 37 records · Page 2Linked to original sources
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

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

Thromboembolic disease prophylaxis in patients with hip fracture: a multimodal approach.

OBJECTIVES: To assess if pneumatic compression in conjunction with chemoprophylaxis is an effective way to reduce the incidence of deep vein thrombosis in orthopedic trauma patients sustaining fragility hip fractures. DESIGN: Two hundred patients admitted to the authors' institution between May 1998 and June 2002 for fractures of the hip were prospectively studied. All patients were treated operatively and received the VenaFlow calf compression device on both lower extremities immediately following surgery. Chemical prophylaxis of either aspirin (n = 67) or warfarin (n = 133) was administered in addition to mechanical compression. A noninvasive serial color flow duplex scan was performed 1 to 11 days postoperatively (mean 4.5 days) to determine the presence or absence of deep vein thrombosis. All patients were followed clinically 3 months postoperatively for a clinical evaluation of symptomatic deep vein thrombosis or pulmonary embolism. RESULTS: Overall, the incidence of deep vein thrombosis was 3.5% (7 of 200) and included only 1 proximal thrombosis (1 out of 200, or 0.5%) and no pulmonary embolism. Five of the 7 patients positive for deep vein thrombosis were in the mechanical compression and warfarin prophylaxis group and 2 were in the aspirin arm of the study. For patients with deep vein thrombosis, the average number of risk factors was 3.71, whereas patients without clots averaged 1.75 clinical risk factors (P < or = 0.05). Three patients in the warfarin group developed bleeding complications (1 with a gastrointestinal bleed and 2 with minor bleeding not at the operative site). No evidence of a symptomatic deep vein thrombosis or pulmonary embolism was reported within a 3-month period following hospitalization. CONCLUSIONS: Our findings suggest mechanical compression with the VenaFlow calf compression device in conjunction with chemoprophylaxis is an effective means of reducing thromboembolic disease in this high-risk population.

Aged↗
PubMed2005

An in vivo rabbit model for cartilage trauma: a preliminary study of the influence of impact stress magnitude on chondrocyte death and matrix damage.

OBJECTIVE: This study was designed to evaluate the postimpact response of the articular cartilage in the rabbit knee after a single traumatic episode. DESIGN: A novel servo-controlled Rabbit Impact Test System (RITS) was developed to apply a well-defined trauma to the femoral condyle in the rabbit knee. The RITS was first used in an in vitro study to determine an appropriate stress to cause cartilage damage without bone fracture. Viable rabbit knees (n = 18) were impacted with stresses of 15 to 50 MPa at a stress rate of 420 MPa/s, the latter corresponding to joint impact rates commonly seen in sports injuries and vehicular accidents. Based on the in vitro study, we performed an in vivo study by impacting the knees of rabbits (n = 9) with a 35 MPa peak stress at a stress rate of 420 MPa/s. The articular cartilage in these knees was analyzed at 0 and 3 weeks after impaction. SETTING: Center for Laboratory Animal Services, Hospital for Special Surgery. SUBJECTS: A total of 27 New Zealand White rabbits were used in this study. INTERVENTION: A rabbit's knee was rigidly immobilized in the adjustable frame of the RITS. A small incision on the knee exposed the lateral condyle and the impactor was positioned perpendicular to the surface of the condyle. The lateral femoral condyle of the left knee was impacted, whereas the right knee was sham operated and used as a control. MAIN OUTCOME MEASUREMENTS: Visual matrix damage, cell viability, and microscopic matrix damage was assessed. RESULTS: In the in vitro study, matrix damage was observed at stress magnitudes > or =30 MPa. However, cell death was initiated at approximately 20 MPa at the articular surface and increased in depth with increasing stress magnitude (2.8 +/- 2% thickness/MPa,). In the in vivo study, visible surface damage was observed immediately after impaction but not at 3 weeks after impaction. At 3 weeks, the articular cartilage showed significant arthritic changes (matrix damage, chondrocyte death, and proteoglycan loss) typical of late-stage osteoarthritis. CONCLUSIONS: Our novel impact test system was able to accurately apply a quantifiable stress magnitude at a constant stress rate to rabbit femoral condyles in the in vitro and in vivo settings. At the time of impaction, the extent of cell death depended with the intensity of trauma (stress magnitude) in which complete cell death was observed in the impacted site at >40 MPa. Under in vivo conditions, the test system was able to consistently produce superficial matrix damage and cell death at 35 MPa stress magnitude at the time of impaction. This resulted in cartilage "arthritic" changes by 3 weeks postinjury.

Animals↗
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↗
PubMed2005

Orthopaedics and the law.

Understanding the relevant legal context is critical to the safe and successful practice of orthopaedic surgery. Specifically, three areas of liability are relevant to most physicians: medical malpractice, products liability, and the liability of health care organizations. Medical malpractice encompasses the professional physician-patient relationship with its implied contract, consent, fiduciary responsibilities, and duty to provide the standard of care, as well as certain common-law duties pertinent in special circumstances. Orthopaedic surgeons who design implants or who have a relationship with a device manufacturer are at risk for liability for a failed product. In general, the hospital entity is responsible for the actions of its physician-employees. Still unclear is the degree to which a physician is obligated to appeal to a third-party payer on behalf of a patient. Physicians should remember that, above all else, common sense with regard to the treatment, informed consent, and advocacy of patients is essential to avoiding many medical-legal pitfalls.

Ethics, Medical↗
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↗
PubMed2004

Nonunions of the distal tibia treated by reamed intramedullary nailing.

OBJECTIVE: The purpose of this study is to determine the efficacy of reamed intramedullary nailing in the treatment of nonunions of the distal one-fourth of the tibia. Nonunions of the distal tibia are particularly difficult to treat given the short distal segment, the proximity to the ankle joint, and the fragile soft-tissue envelope. Intramedullary nailing is an attractive solution to this problem because it avoids extensive dissection, and the implant remains intraosseous, posing minimal problem for the soft tissues. DESIGN: Retrospective review of patient charts and radiographs. SETTING: Tertiary care orthopaedic hospital. PATIENTS/PARTICIPANTS: Thirty-two patients with nonunions of the distal one-fourth of the tibia. Prior treatments included casting, internal fixation with plates and screws, intramedullary nailing, and external fixation. Seven patients had a history of infection, but no patient had signs of active infection at the time of surgery. INTERVENTION: Study patients were treated by reamed, locked intra-medullary nailing. MAIN OUTCOME MEASUREMENTS: Main outcome measurements included time to union, correction of deformity, and complications including infection and reoperation. RESULTS: Average length of follow-up was 25 months (range 4-81 months). Twenty-nine out of 32 patients achieved union at an average of 3.5 months after reamed, locked intramedullary nailing. Of the remaining three, 2 patients united after dynamization (one at 4 months after dynamization and the other at 7 months), and the third patient united 4 months after exchange nailing. Deformity was corrected to a maximum of 4 degrees in all planes. Four patients had positive intraoperative cultures, and only 2 required removal of the nail after achieving union to control infection. There were no signs of chronic osteomyelitis in these 2 patients at the date of the last follow-up visit; 5.5 years and 2 years following nail removal. CONCLUSIONS: Reamed, locked intramedullary nailing is a reliable and safe procedure in the treatment of nonunions in the distal one-fourth of the tibia, even in the setting of prior infection or external fixation. It allows for excellent correction of deformity, which is an essential component of the procedure.

Adolescent↗
PubMed2004

Operative treatment of tibial plateau fractures in patients older than 55 years.

Surgical treatment of tibial plateau fractures in the older patient poses an additional challenge because of the underlying condition of the bone and articular surface. We sought to identify risk factors for poorer outcomes in the operative treatment of displaced tibial plateau fractures in older patients. Thirty-nine displaced tibial plateau fractures in patients 55 years and older were treated operatively. Patients were evaluated objectively with Rasmussen clinical and radiologic scoring techniques, and the Short Musculoskeletal Function Assessment and the Short-Form 36 self-assessment instruments. The Rasmussen clinical and radiologic scoring systems, used on average 2.54 years postoperatively, found acceptable results in 87.2% and 82.1% of patients, respectively. The fracture classification of Schatzker was not predictive of results. External fixation was associated with significantly poorer results. Increasing age was associated with poorer clinical and self-assessment scores, although preexisting degenerative joint disease was not. The results from the Short-Form 36 indices were not significantly worse for our study patients. The average Short Musculoskeletal Function Assessment score of our study patients indicated poorer function for mobility than a normative group. Operative treatment of this injury in this population can result in favorable outcomes as evaluated by clinical, radiographic, and self-assessment criteria.

Age Factors↗
PubMed2004

ORIF of delayed unions and nonunions of distal humeral fractures. Surgical technique.

BACKGROUND: The purpose of the present retrospective study was to evaluate the results of open reduction and internal fixation of delayed unions and nonunions of fractures of the distal part of the humerus. METHODS: Between 1976 and 2001, fifty-two patients with a delayed union (thirteen patients) or nonunion (thirty-nine patients) of the distal part of the humerus were treated with open reduction and internal fixation along with selective elbow joint arthrolysis and bone-grafting. The average time to presentation was eighteen months (range, two to 192 months) after the injury. Thirty-nine of the fifty-two patients had undergone an average of 1.6 previous operations. There were twenty-seven supracondylar, six transcondylar, thirteen intercondylar, two lateral condylar, and four medial condylar delayed unions or nonunions. The average duration of follow-up was thirty-three months (range, three to 198 months). RESULTS: Fifty-one of the fifty-two patients had healing of the delayed union or nonunion after the index operation; the average time to union was six months (range, two to twenty-four months). The average range of elbow motion increased from 71 degrees preoperatively to 94 degrees postoperatively. Complications included two superficial infections, two deep infections, and five cases of ulnar neuropathy. Fifteen patients (29%) needed additional surgery after the index procedure. Specifically, seven patients underwent removal of prominent hardware; six underwent hardware removal along with excision of heterotopic bone, ulnar neurolysis, and/or manipulation under anesthesia; one underwent irrigation and débridement; and one underwent compartment release. CONCLUSIONS: Open reduction through an extensile exposure and rigid internal fixation consistently results in healing of a delayed union or nonunion of the distal part of the humerus. An improved range of motion of the elbow can be achieved by securing the site of the nonunion and performing aggressive elbow joint arthrolysis and soft-tissue releases in patients with severe contractures.

Fracture Fixation, Internal↗
PubMed2004

Periprosthetic fractures of the acetabulum.

Periprosthetic fractures of the acetabulum after total hip arthroplasty are uncommon, but are increasing in number and severity. These fractures may occur intraoperatively, during the perioperative period, or many years after the total hip arthroplasty. Periprosthetic fractures of the acetabulum vary in severity and may involve stress fractures of the pubis or medial wall, significant bone loss secondary to osteolysis and subsequent loss of column integrity, or complete pelvic discontinuity. Treatment differs depending on the complexity of the fracture and the stability of the acetabular prosthesis. Surgical treatment for an unstable acetabulum should stabilize the bony columns of the acetabulum, provide bone grafting of defects, and should maintain adequate bone stock for replacement of a stable acetabular implant. Strict adherence to the principles of fracture surgery is required to achieve bony union of the acetabular columns and provide a stable environment for reimplantation of an acetabular component.

Acetabulum↗
PubMed2004

Minimally invasive percutaneous plate osteosynthesis of fractures of the distal tibia.

Fractures of the distal tibia are notoriously difficult to treat, and traditional methods of fixation are often fraught with soft-tissue complications. With recent emphasis on meticulous handling and preservation of the soft-tissue envelope, minimally invasive percutaneous plate osteosynthesis has become a safe and reliable method of treating these fractures. This technique involves conventional open reduction and internal fixation of the fibula and spanning external fixation of the tibia until the soft-tissue swelling subsides. Subsequently, limited open reduction and internal fixation of displaced articular fragments is performed through small incisions based on CT evaluation. This is followed by minimally invasive percutaneous plate osteosynthesis of the tibia, in which the plafond is attached to the tibial shaft using a variety of commercially available plates.

Bone Plates↗