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Biomedical subjects

David L Helfet

Publications and source records attributed to David L Helfet.

At least 55 records · Page 3Linked to original sources
PubMed2004

Has locked plating completely replaced conventional plating?

The 2 main approaches to fracture plate fixation--compression plating and internal splinting--result in differing biomechanics and subsequent healing response patterns. A number of advantages to using the newer internal fixators have been described, but there are still several indications for traditional compression plating.

Biomechanical Phenomena↗
PubMed2003

First clinical results of the Locking Compression Plate (LCP).

The Locking Compression Plate (LCP) is a new screw-plate system that offers the possibility of inserting conventional and locking head screws into the specially designed combination holes. It represents a further development of the PC-Fix and the LISS and was released for clinical application in March 2000. In a prospective multicentre study, the new system was used to treat 144 patients (f: 67, m: 77; average age: 51.4 years) with 169 fractures: of these, 57 were tibial fractures, 45 humerus, 19 radius and 18 femoral. After one year, clinical and radiological follow-up assessment was carried out on 127 patients with 151 fractures (88%). In 130 fractures (86%), healing took place within the expected period and without complication or secondary dislocation ("uneventful healing"). In 19 patients, a total of 27 unexpected complications occurred ("adverse events"), in which 18 revision operations were necessary in 13 patients: five for implant loosening/pull-out, four for plate failure, one for non-union, five for secondary fractures immediately adjacent to the implant after a subsequent injury and two for infection. Analysis by a committee of experts indicated that mechanical complications arose entirely from technical errors of application (incorrect fixation technique, incorrect choice of plate). No purely implant-related complications were observed. The new system can be regarded as technically mature. It offers numerous fixation possibilities and has proven its worth in complex fractures situations and in revision operations after the failure of other implants. A good knowledge of biomechanics is essential as well as precise preoperative planning.

Adolescent↗
PubMed2003

Subtrochanteric fracture after cannulated screw fixation of femoral neck fractures: a report of four cases.

Subtrochanteric fractures after screw or pin fixation of femoral neck fractures are a recognized complication. No literature is available on this complication after fixation using the recently popularized cannulated screws. We present our experience in treating four of these complications. The common denominator for all four patients seemed to be an entry point in the lateral cortex below the level of the most inferior edge of the lesser trochanter.

Aged↗
PubMed2003

Influence of stress magnitude on water loss and chondrocyte viability in impacted articular cartilage.

The objective of this study was to assess mechano-biological response of articular cartilage when subjected to a single impact stress. Mature bovine cartilage explants were impacted with peak stresses ranging from 10 to 60 MPa at a stress rate of 350 MPa/s. Water loss, matrix axial deformation, dynamic impact modulus (DIM), and cell viability were measured immediately after impaction. The water loss through the articular surface (AS) was small and ranged from 1% to 6% with increasing peak stress. The corresponding axial strains ranged from 2.5% to 25%, respectively, while the DIM was 455.9 +/- 111.9 MPa. Chondrocyte death started at the articular surface and increased in depth to a maximum of 6% (70 microns) of the cartilage thickness at the highest stress. We found that the volumetric (axial) strain was more than twice the amount of water loss at the highest peak stress. Furthermore, specimens impacted such that the interstitial water was forced through the deep zone (DZ) had less water loss, a higher DIM, and no cell death. These findings appear to be due to matrix compaction in the superficial region causing higher compressive strains to occur at the surface rather than in the deeper zones.

Apoptosis↗
PubMed2003

Open reduction and internal fixation of delayed unions and nonunions of fractures of the distal part of the humerus.

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. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.

Adolescent↗
PubMed2003

Bilateral Monteggia fractures.

The current concepts of anatomic and stable fixation followed by early mobilization in Monteggia fractures have clearly resulted in improvements in treatment and outcome. Bilateral Monteggia fractures are unusual and to the best of our knowledge have not been the subject of any reports in the literature. In this case report, we describe the operative technique for treating bilateral Monteggia fractures and the common pitfalls associated with this treatment. Despite the surgical and rehabilitative challenges posed by our patient's case, excellent results were obtained for both elbows.

Accidental Falls↗
PubMed2003

Efficacy of telemedicine in the initial management of orthopedic trauma.

In order to determine the clinical usefulness of teleradiology in the initial treatment of musculoskeletal injury, a panel of orthopedic trauma surgeons developed a survey that was presented to participants at the annual meeting of the Orthopedic Trauma Association. Selected orthopedic trauma cases from a level-1 trauma and a tertiary care center were presented orally (including a description and interpretation of the radiographic findings) to volunteer participants. Questions related to treatment and patient management were then asked prior to and following the participants' viewing of digital radiographic images. Overall, 90% of respondents found telemedicine useful. They disagreed with the verbal radiographic report 49% of the time. Respondents changed their mind with regard to the need for admission 17% of the time; surgical indications, 22% of the time; and need for more information, 30% of the time.

Decision Making↗
PubMed2002

MRI assessment of the posterior acetabular wall fracture in traumatic dislocation of the hip in children.

Traumatic hip dislocations associated with posterior wall fractures of the acetabulum in the pediatric population are in general a consequence of high-energy trauma. After expeditious reduction, instability mandates for further diagnosis and intervention. Plain radiographs or computerized tomography (CT) scans can misjudge the involvement of the posterior wall of the acetabulum due to the partially calcified nature of the pediatric bone. We present two cases of pediatric traumatic hip dislocation associated with posterior wall fractures of the acetabulum. In both cases, obvious postreduction instability was noted without conclusive findings of etiology on plain X-rays or CT scans. Magnetic resonance imaging (MRI) disclosed an extensive posterior wall traumatic involvement in both cases and helped to decide in favor of open reduction of the hip and internal fixation of the posterior wall fragment.

Acetabulum↗
PubMed2002

Magnetic resonance imaging of the multiple-ligament injured knee.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) in detecting soft tissue, neurovascular, and bony injury after multiple ligament knee injury, including knee dislocation. MATERIALS AND METHODS: A retrospective search was performed for patients presenting with reported knee dislocation from May 1993 through May 2000 who underwent both MRI and surgical reconstruction. Twenty-one patients met these criteria (15 men and six women; age range 14 to 75 years; mean 32.6 years). Magnetic resonance diagnoses of soft tissue and bony injury were compared with the patients' operative findings. MRA of the popliteal vessels was performed in seventeen of our twenty-one patients, and the results of these studies are described. RESULTS: Multiple ligamentous, tendinous, meniscal, chondral, osseous, and neural injuries were seen. There was excellent correlation (kappa > 0.8) between the magnetic resonance and operative findings with regard to the size and location of tears. Regarding meniscal tears, the type (e.g., bucket, radial split, meniscocapsular separation) and location correlated well with surgery. All ten nerve injuries noted on magnetic resonance were confirmed at surgery. Six of our patients had both conventional angiograms and MRAs with 100 percent agreement between the studies. In one patient an intimal flap in the popliteal artery was seen on MRA and confirmed on conventional angiographic images. CONCLUSION: MRI is an accurate method of assessing soft tissue, osseous, and neural damage after knee dislocation. Our early experience with popliteal fossa MRA is encouraging with complete agreement between the MRA and conventional angiography in patients who had both studies.

Adolescent↗
PubMed2002

Open reduction and internal fixation of humeral nonunions : a biomechanical and clinical study.

BACKGROUND: Several studies have compared different methods for fixation of the midpart of the humeral shaft, but there are only scattered data regarding which type of plate construct provides the best fixation for humeral nonunion. The objectives of this study were (1) to obtain objective data on the performance of four different plate constructs used for fixation of humeral nonunion, and (2) to report our clinical experience with plate fixation of thirty-seven nonunions of the midpart of the humeral shaft. METHODS: In the first part of the study, four plate constructs were compared in a Sawbones model. The groups consisted of (1) a posterior limited-contact dynamic compression plate alone; (2) a posterior limited-contact dynamic compression plate and an interfragmentary screw; (3) a posterior limited-contact dynamic compression plate, a lateral 3.5-mm reconstruction plate, and an interfragmentary screw; and (4) a posterior limited-contact dynamic compression plate and a lateral 3.5-mm reconstruction plate. Tests were performed with use of an MTS Bionix machine in anterior-posterior four-point bending, medial-lateral four-point bending, and external rotation torque. In the second part of the study, the charts of thirty-seven consecutive patients in whom a nonunion of the midpart of the humeral shaft had been treated with plate fixation were reviewed retrospectively. The average age of the patients was forty-eight years (range, thirteen to seventy-eight years). Nineteen patients were treated with a single posterior plate, and eighteen were treated with a two-plate construct with the plates parallel and lying at 90 degrees to each other. All of the nonunions were treated with bone-grafting, and an interfragmentary screw was used in thirty-six of the thirty-seven patients. Radiographs and the clinical status were evaluated at an average of thirteen months postoperatively. RESULTS: The biomechanical testing showed that the two-plate constructs were significantly stiffer than the single-plate constructs in all test modes (p < 0.05). In the clinical part of the study, thirty-four (92%) of the nonunions healed without complications at an average of 4.8 months. Two nonunions treated with the two-plate construct and one treated with one plate failed to heal. CONCLUSIONS: No significant difference in the healing rate was found between the two clinical groups (p = 0.4, beta = 0.9), and the overall healing rate was 92%. However, a two-plate construct with the plates at right angles is mechanically stiffer than a single-plate construct, which might be helpful if rigid stabilization of the humerus at the midshaft level is needed.

Adolescent↗
PubMed2002

Expression and activation of the BMP-signaling components in human fracture nonunions.

BACKGROUND: The potential use of bone morphogenetic proteins (BMPs) to promote bone-healing is of great interest to orthopaedic surgeons. Although the complex mechanism leading from the local presence of BMP (whether endogenous or exogenous) to bone formation is increasingly understood, limited information is available as to whether endogenous BMPs, their receptors, or other molecules involved in their signal transduction, such as Smad1, are present or disappear during the development of fracture nonunions. The purpose of the present study was to determine, by immunohistochemical analysis, whether BMPs, BMP receptors, or Smad1 disappear from tissues during the development of a fracture nonunion. METHODS: Twenty-one patients (average age, sixty-one years; range, thirty to eighty-five years) with a delayed union (four patients) or a nonunion (seventeen patients) were included. The average duration of the delayed union or nonunion was twenty-two months (range, 3.5 to 120 months). With use of immunohistochemical analysis, we studied the localization of BMP-2, BMP-4, and BMP-7 and their receptors BMPR-IA, BMPR-IB, and BMPR-II as well as pSmad1. With use of a pSmad1 antibody, we also studied whether the BMP receptors that were expressed were activated. RESULTS: The immunohistochemical localization of all seven BMP-signaling components was demonstrated in seventeen (81%) of the twenty-one patients. The remaining four patients lacked one or more of the components. Areas of newly formed bone had the highest percentage of positively staining cells, with the staining generally decreasing in areas remote from bone formation. However, even in areas of dense fibrous tissue and in specimens that lacked newly formed bone, immunostaining was still present. The staining patterns showed co-localization of the BMP-2, BMP-4, and BMP-7 proteins with the BMP receptors. The presence of pSmad1 signified the activated state of the BMP receptors, which implies that the BMP signal is transduced inside the cell.

Adult↗
PubMed2002

Tibiotalocalcaneal fusion with a retrograde intramedullary nail: clinical and functional outcomes.

Severe arthrosis and deformity of the ankle and subtalar joints are debilitating problems that can be difficult to treat. We retrospectively reviewed and functionally assessed 15 patients who had undergone tibiotalocalcaneal fusion with a retrograde intramedullary nail. The procedure had been a salvage procedure for severe arthrosis and deformity of the ankle and subtalar joints. Minimum follow-up was 2 years. Solid fusion was achieved in 14 of 15 patients. Mean time to union was 16.5 weeks. Ankle-Hindfoot Scale scores showed excellent pain relief at union. Subjective gait disturbances were common postoperatively, though patient satisfaction and the return-to-work rate were high (93% and 80%, respectively). The 12 complications included nonunion, malunion, skin problems, plantar pain, infection, and painful hardware. We advocate using a retrograde nail as a salvage technique in complex posttraumatic or postsurgical settings.

Adult↗