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Biomedical subjects

D L Helfet

Publications and source records attributed to D L Helfet.

At least 19 recordsLinked to original sources
PubMed2003

BMP signaling components are expressed in human fracture callus.

Of the various growth factors involved in the healing response after a fracture, bone morphogenetic proteins (BMPs) are emerging as key modulators. BMPs exert their effects by binding to a complex of type I and type II receptors leading to the phosphorylation of specific downstream effector proteins called Smads. The current study examined the presence of BMP signaling components in human callus obtained from five nascent malunions undergoing fracture fixation. These callus samples represented various stages of bone healing and a mixture of endochondral and intramembraneous bone healing. We performed immunohistochemistry on the callus, using antibodies for BMP (BMP-2,-3,-4,-7), their receptors (BMPR-IA, -IB, -II), and phosphorylated BMP receptor-regulated Smads (pBMP-R-Smads). Active osteoblasts showed fairly consistent positive staining for all BMPs that were examined, with the immunoreactivity most intense for BMP-7 and BMP-3. Immunostaining for BMPs in osteoblasts appeared to colocalize with the expression of BMPR-IA, -IB, and -II. Positive immunostaining for pBMP-R-Smads suggests that the BMP receptors expressed in these cells are activated. Staining for BMPs in cartilage cells was variable. The immunostaining appeared stronger in more mature cells, whereas staining for BMP receptors in cartilage cells was less ubiquitous. However, the expression of pBMP-R-Smads in cartilage cells suggests active signal transduction. Fibroblast-like cells also had a variable staining pattern. Overall, our findings indicate the presence of BMPs, their various receptors, and activated forms of receptor-regulated Smads in human fracture callus. To the best of our knowledge, this is the first study that documents the expression of these proteins in human fracture tissue. Complete elucidation of the roles of BMP in bone formation will hopefully lead to improved fracture healing care.

Adolescent↗
PubMed2002

Anteroinferior plating of midshaft clavicular nonunions.

Many different techniques have been reported for the treatment of clavicular nonunions. Those techniques involving screws and plate generally position the plate on the superior (subcutaneous) surface of the clavicle. To decrease the risk of screw pull-out and prominence of the instrumentation, we currently perform anteroinferior plating using a 3.5-millimeter pelvic reconstruction plate with a lag screw and bone graft. A consecutive group of twelve patients with midshaft clavicular nonunions was treated with this technique. All nonunions united after an average of 3.6 months (range 2 to 8 months). All patients regained full function and mobility of the shoulder. The technique as described in this article illustrates a successful modification of the traditional plating technique of midshaft clavicular nonunions. We conclude that anteroinferior plating is a reliable and safe technique that leads to high rates of bony union in midshaft clavicular nonunions.

Adult↗
PubMed2001

An introduction to the minimally invasive osteosynthesis of intra-articular calcaneal fractures.

The approach to the treatment of intra-articular calcaneal fractures has often been the subject of discussion. The results achieved with both operative and non-operative management remain to some extent unpredictable. Minimally invasive osteosynthesis offers an alternative approach, especially in those cases in which open reduction would be hazardous and non-operative treatment inadequate. This technique requires minimal dissection and preserves subtalar motion almost completely. The authors believe that displaced intra-articular calcaneal fractures are best treated through operative intervention. Restoration of articular congruity is an integral, though not necessarily sufficient, component of a successful long-term outcome following calcaneal fracture. The extra-articular dimensions of the calcaneus must be restored in order to tolerate standard shoe-wear, maintain a functional range of talocalcaneal motion and avoid subsequent tibiotalar arthrosis. However, in certain circumstances open reduction may be associated with an unacceptably high complication rate. In these cases, the authors have found a "minimally invasive" osteosynthesis technique useful in dealing with competing goals. In our experience, this technique can, when used appropriately, result in a functional recovery of the patient suffering a calcaneal fracture.

Aged↗
PubMed1999

Effect of impact load on articular cartilage: cell metabolism and viability, and matrix water content.

Significant evidence exists that trauma to a joint produced by a single impact load below that which causes subchondral bone fracture can result in permanent damage to the cartilage matrix, including surface fissures, loss of proteoglycan, and cell death. Limited information exists, however, on the effect of a varying impact stress on chondrocyte biophysiology and matrix integrity. Based on our previous work, we hypothesized that a stress-dependent response exists for both the chondrocyte's metabolic activity and viability and the matrix's hydration. This hypothesis was tested by impacting bovine cartilage explants with nominal stresses ranging from 0.5 to 65 MPa and measuring proteoglycan biosynthesis, cell viability, and water content immediately after impaction and 24 hours later. We found that proteoglycan biosynthesis decreased and water content increased with increasing impact stress. However, there appeared to be a critical threshold stress (15-20 MPa) that caused cell death and apparent rupture of the collagen fiber matrix at the time of impaction. We concluded that the cell death and collagen rupture are responsible for the observed alterations in the tissue's metabolism and water content, respectively, although the exact mechanism causing this damage could not be determined.

Animals↗
PubMed1998

[Avascular femur head necrosis as severe complication after femoral intramedullary nailing in children and adolescents].

Nailing of femoral fractures before closure of the growth plates may lead to avascular necrosis of the femoral head in 3-4% of cases. In addition to the 14 cases described in the literature we present 3 more. Analysis of these cases reveals a common pathogenesis. The nails were all inserted anterograde and were designed for the adult femur. The problem appears to be related to the large diameter of the nail and its entry point in the relatively small femoral neck basis, close to the vessels supplying the femoral head. The role of the open physis remains unclear. Even though the complication of femoral head necrosis is rare, it is a severe complication. Therefore we do not recommend anterograde femoral nailing, using the classic entry point, in children or adolescents. We believe that there is a need for a new design of femoral nail. If both femoral head necrosis and coxa valga are to be avoided, we suggest that the entry point of the nail should be dorsolateral, below the trochanteric physis.

Adolescent↗
PubMed1998

Bladder incarceration in a traumatic symphysis pubis diastasis treated with external fixation: a case report and review of the literature.

Fractures of the pelvis constitute a small but significant proportion of skeletal injuries. However, they are associated with significant morbidity and mortality, including damage to the urogenital system, especially the urethra and urinary bladder. We report the rare finding of bladder herniation and entrapment after reduction of a traumatic symphyseal diastasis by external fixation and the diagnosis of these injuries with computed tomography. A comprehensive review of the literature is also performed, to improve understanding and provide guidelines for evaluation and treatment of pelvic injuries with suspected bladder involvement.

Adult↗
PubMed1998

Outer gloves in orthopaedic procedures: a polyester/stainless steel wire weave glove liner compared with latex.

OBJECTIVE: To compare the efficacy of traditional double latex gloving with that of a highly cut-resistant polyester/stainless steel wire weave glove (PSSWWG) over a single latex inner glove for the prevention of perforation of the inner latex glove. DESIGN: The primary surgeon and first assistant were involved in a prospective randomized study. Group I consisted of twenty-five procedures in which double latex gloves were used. Group II consisted of twenty-five procedures in which a PSSWWG liner was worn over an inner latex glove. All inner gloves were tested for perforations; all gloves exchanged that were presumed to have a perforation were noted and also tested. The type and length of the procedure were recorded. The dominant hand was recorded for all participants, along with their comments on the PSSWWG liner's performance. SETTING: Orthopaedic Trauma Service, Hospital for Special Surgery. New York. PATIENTS/PARTICIPANTS: Major operative cases, November 1996 to February 1997. MAIN OUTCOME MEASUREMENTS: Inner latex glove perforations. RESULTS: With the use of PSSWWG liners, the percentage of inner gloves found with a perforation dropped from 19 percent in the double latex group to 15 percent in the PSSWWG liner group (not statistically significant, p = 0.4). Two thirds of the perforations were in the primary surgeon's gloves, located in either the index finger or thumb. Nearly 80 percent of all perforations went unrecognized in both groups. Ninety-five percent of all perforations were in gloves that had been in use for more than 120 minutes (statistically significant, p = 0.01). CONCLUSIONS: The particular cut-resistant glove studied (Sceptor) did not significantly reduce the rate of inner glove perforations. Other studies with different cut-resistant glove types and protocols have proven the liners effective. We would still recommend using outer cloth or cut-resistant type gloves when bone fragments are being manipulated or when using sharp implants or saws. At a minimum, surgical gloves should be changed every two hours.

Equipment Design↗
PubMed1998

Cardiac arrest as a result of intraabdominal extravasation of fluid during arthroscopic removal of a loose body from the hip joint of a patient with an acetabular fracture.

The case of a fifty-year-old man who suffered an isolated, associated, both-column fracture of the left acetabulum is presented. He underwent an uncomplicated open reduction and internal fixation through an ilioinguinal approach. A follow-up computed tomographic scan was performed postoperatively, which documented intraarticular fragments. Hip arthroscopy was performed to remove the fragments. During the procedure, arthroscopic fluid extravasated through the fracture site under pump pressure and resulted in an intraabdominal compartment syndrome that presented as cardiopulmonary arrest. An emergent exploratory laparotomy was performed to release the fluid and resume blood flow. Despite prolonged asystole, the patient survived without neurologic sequelae. The literature on compartment syndrome secondary to arthroscopic procedures is reviewed. Because of this previously unreported potentially lethal complication, we do not advocate hip arthroscopic procedures for acute or healing acetabular fractures.

Acetabulum↗
PubMed1998

Retrograde intramedullary nailing of supracondylar femoral fractures.

As an alternative to standard AO/Association for the Study of Internal Fixation plate and screw techniques, retrograde intramedullary locked nailing of supracondylar and intracondylar (AO/Association for the Study of Internal Fixation Type 33) fractures is reviewed. This includes a historic review, the technique for knee arthrotomy, fracture reduction and nail insertion, and the reported clinical and biomechanical results. The retrograde intramedullary locked nail is a viable alternative for the treatment of AO/Association for the Study of Internal Fixation Type 33-A and some C supracondylar femoral fractures and should be part of the internal fixation armamentarium, however, it does not replace the standard biologic plate and screw techniques for most fractures.

Bone Nails↗
PubMed1997

Minimally invasive plate osteosynthesis of distal fractures of the tibia.

Minimally invasive plate osteosynthesis of distal tibial fractures is technically feasible and may be advantageous in that it minimizes soft tissue compromise and devascularization of the fracture fragments. The technique involves open reduction and internal fixation of the associated fibular fracture when present, followed by temporary external fixation of the tibia until swelling has resolved. Subsequent limited, but open reduction and internal fixation of the articular fragments when displaced followed by minimally invasive plate osteosynthesis of the tibia utilizing precontoured tubular plates and percutaneously placed cortical screws is performed. The semitubular plate was chosen because it adapts more easily to the bone contours than the stiffer small fragment LC-DCP does. Twenty patients (age 25-59 years) with unstable intraarticular or open extraarticular fractures have been treated including 12 A-type, 1 B-type and 7 C-type fractures according to the AO classification. Two fractures were open (both Gustilo Type I). Closed soft tissue injury was graded according to Tscherne with 3 type C0, 7 type C1, 7 type C2 and 1 type C3. All fractures healed without the need for a second operation. Time to full weight-bearing averaged 10.7 weeks (range 8-16 weeks). Two fractures healed with > 5 degrees varus alignment and 2 fractures healed with > 10 degrees recurvatum. No patient had a deep infection. The average range of motion in the ankle for dorsiflexion was 14 degrees (range 0-30 degrees) and plantar flexion averaged 42 degrees (range 20-50 degrees). With longer follow-up and a larger number of patients, the authors feel confident that the minimally invasive technique for plate osteosynthesis for the treatment of distal tibial fractures will prove to be a feasible and worthwhile method of stabilization while avoiding the severe complications associated with the more standard methods of internal or external fixation of those fractures.

Adult↗
PubMed1997

Practical management of venous thromboembolism following pelvic fractures.

The management of thromboembolic complications remains one of the most controversial issues in the care of patients with pelvic and acetabular fractures. Recent studies have indicated that the incidence of proximal deep vein thrombosis is much higher than was previously believed. These patients should be managed with a formal institutional protocol that includes universal prophylaxis, supplemented in some cases by screening for deep vein thrombosis.

Algorithms↗
PubMed1997

Intraoperative monitoring of motor pathways during operative fixation of acute acetabular fractures.

OBJECTIVE: To determine whether intra-operative spontaneous electromyography (EMG) was superior to somatosensory evoked potentials (SSEP) in the prevention of iatrogenic sciatic nerve injury. DESIGN: Prospective, consecutive. SETTING: Tertiary referral, teaching Hospital in New York City. PATIENTS: Seventy-four patients with acutely displaced acetabular fractures. MAIN OUTCOME MEASURE: Group A consisted of 24 patients who underwent intraoperative sciatic nerve monitoring using SSEP only. Group B consisted of 50 patients who underwent monitoring using both SSEP and spontaneous EMG. Motor potentials were recorded from the tibialis anterior, peroneus longus, abductor hallucis, and flexor hallucis longus muscles. All patients had independent preoperative and postoperative evaluations by the same neurologist. RESULTS: One iatrogenic sciatic nerve injury occurred in group A and none in group B. Prolonged sciatic nerve compromise, demonstrated by significant intraoperative SSEP changes, occurred 2.4 times per case in group A and only 0.8 times per case in group B. In group B, spontaneous EMG noted compromise an average of 3.6 times per case (p < 0.0001). CONCLUSIONS: The results of this study support spontaneous EMG as feasible and superior to SSEP monitoring in detecting intraoperative sciatic nerve comprise in acute acetabular fracture surgery. Spontaneous EMG permits earlier detection of intraoperative sciatic nerve comprise, allowing a more rapid response of the surgical team to noxious nerve stimuli. This may prevent permanent neurologic sequellae.

Acetabulum↗
PubMed1997

Effect of impact load on articular cartilage: development of an intra-articular fracture model.

OBJECTIVES: To investigate the biological and mechanical effects of a single-impact load on articular cartilage. DESIGN: An in vitro laboratory study was performed using mature bovine cartilage and bone, and isolated cartilage explants. Each specimen was impacted with a single load applied with a specially designed impactor and materials test machine. Chondrocyte metabolic activity and cartilage structural integrity was investigated using force displacement curves, radionuclide labeling, histology, and changes in water content. SETTING: Laboratory for Soft Tissue Research, New York, New York, U.S.A. SPECIMENS: Viable mature bovine cartilage and cartilage and bone explants. MAIN OUTCOME MEASUREMENTS: Mechanical failure, proteoglycan synthesis, water content, histology, radiography, and scanning electron microscopy changes occurring during the twenty-four-hour period immediately following impact. RESULTS: Force/displacement curves for the cartilage and bone explants demonstrated two failure-stress peaks, the first at fifty megapascals, representing cartilage failure, and a second peak at seventy-five megapascals, representing bone failure. Fine grain radiographs, histology, and scanning electron microscopy all confirmed the destruction of the cartilage in the area of direct impact (zone I) and subchondral bone failure and the detachment of the cartilage within the lesser impacted area (zone II). Proteoglycan synthesis was reduced significantly (p < 0.05) in the areas of direct impact (zone I) compared with areas with less or no impact (zones II and III, respectively). Significantly greater water content (p < 0.05) was found within the cartilage of zone I compared with zones II and III. CONCLUSIONS: Significant and possibly irreversible articular cartilage damage occurs after a single high-energy impact load.

Animals↗
PubMed1997

The detection and management of proximal deep venous thrombosis in patients with acute acetabular fractures: a follow-up report.

OBJECTIVE: To determine the efficacy of a thromboprophylaxis protocol that included deep venous thrombosis (DVT) prophylaxis (subcutaneous heparin), preoperative screening with magnetic resonance venography (MRV), and therapeutic management (vena caval interruption preoperatively, therapeutic heparin anticoagulation postoperatively) when indicated. DESIGN: Prospective, consecutive. SETTING: Tertiary referral, teaching hospital in New York City. PATIENTS: One hundred one patients with acutely displaced acetabular fractures. MAIN OUTCOME MEASURE: Preoperative MRV was performed to assess vascular structures. Patients with proximal DVT received vena caval filter interruption preoperatively and therapeutic warfarin postoperatively. Patients without proximal DVT received only subcutaneous heparin preoperatively and low-dose warfarin postoperatively. RESULTS: Forty-nine asymptomatic thrombi were identified in thirty-four of 101 patients (34 percent). Location of thrombi were in the popliteal vein in four of forty-nine patients (8 percent), superficial femoral vein in eight of forty-nine (16 percent), common femoral vein in thirteen of forty-nine (27 percent), external iliac vein in six of forty-nine (12 percent), internal iliac vein in fourteen of forty-nine (29 percent), and common iliac vein in four of forty-nine (8 percent). Thrombi were isolated to the injured extremity in twenty-six of thirty-four patients (76 percent), bilateral in four of thirty-four (12 percent), and isolated to the uninjured extremity in four of thirty-four (12 percent). Twenty-six of the thirty-four patients with proximal thrombi received preoperative vena caval filters. As a result of this protocol, only one patient (1 percent) developed a nonfatal pulmonary embolism. CONCLUSION: MRV is a sensitive screening examination that allows the placement of inferior vena caval filters based on documented proximal thrombosis. We anticipate that preoperative DVT screening with MRV will significantly decrease the incidence of fatal pulmonary embolism in this high-risk population.

Acetabulum↗
PubMed1996

Thromboembolic complications in patients with pelvic trauma.

Patients with pelvic trauma are known to be at increased risk for the development of thromboembolic complications. The incidence of deep venous thrombosis in patients with pelvic fractures is 35% to 60%. Proximal deep venous thrombosis, which is most likely to result in pulmonary embolism, occurs in 25% to 35% of these patients, and almost 1/2 of all proximal thrombi will be in the pelvic veins. The incidence of symptomatic pulmonary embolism in the pelvic trauma population is 2% to 10% whereas a greater proportion of patients will have clinically silent pulmonary embolism. Fatal pulmonary embolism occurs in 0.5% to 2% of patients with pelvic trauma. The cornerstone of effective management is prophylaxis and the most commonly used forms include low dose heparin, low molecular weight heparin, mechanical devices, and in some studies, inferior vena caval filters. Based on a critical review of the literature, in algorithm is proposed for the management of thromboprophylaxis in this trauma subgroup. This includes prophylaxis, screening, and treatment when proximal thrombosis is identified. Such a systematic approach to this potentially catastrophic problem may decrease the morbidity and mortality associated with thromboembolic complications in these patients.

Fractures, Closed↗