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Biomedical subjects

D J Hak

Publications and source records attributed to D J Hak.

14 recordsLinked to original sources
PubMed2001

Prevention of venous thromboembolism in trauma and long bone fractures.

Patients sustaining traumatic injuries are at high risk for the development of venous thromboembolism. The reported incidence of deep venous thrombosis in trauma patients ranges from 20 to 90%. The reported incidence of pulmonary embolism in trauma patients varies between 2.3 and 22%. The aging population and the survival of more severely injured patients may suggest an increasing risk of thromboembolism in the trauma patient population. There have been few randomized prospective studies assessing methods of thromboembolism prophylaxis in trauma patients. Controversy exists as to the optimal method of prophylaxis in this high-risk population. Contraindications arising from associated injuries often limit the potential options for prophylaxis in patients with trauma. Large prospective randomized studies are needed to determine the most effective means of prophylaxis in trauma patients, who have a wide range of both isolated and combined injuries. Future studies should also address the duration of prophylaxis because many trauma patients remain immobile for an extended time.

Aged↗
PubMed1999

Severity of injuries associated with traumatic hip dislocation as a result of motor vehicle collisions.

BACKGROUND: Previous reports have shown a high rate of associated injuries in patients who sustain traumatic hip dislocation. Since these earlier reports appeared, improvements have been made in passenger safety systems and the rate of restraint usage has increased. The purpose of this study was to review the associated injuries present in a current series of patients who sustained traumatic hip dislocation as a result of motor vehicle collisions. METHODS: We retrospectively reviewed our trauma registry and identified 66 patients who sustained traumatic hip dislocation as a result of motor vehicle collisions. Thirty patients (45%) were restrained and 36 (55%) were unrestrained. Airbags were known to have deployed in 14 cases. RESULTS: The incidence of associated injuries was 95% (63 patients). Orthopedic injuries alone were seen in 22 patients (33%), whereas associated injuries were seen in 44 patients (67%). Abdominal injuries were present in 10 patients (15%), thoracic injuries were present in 14 patients (21%), closed head injuries were present in 16 patients (24%), and craniofacial injuries were present in 14 patients (21%). Acetabular fractures were seen in 46 patients (70%), femoral head fractures were identified in 9 patients (14%), and other extremity fractures occurred in 26 patients (39%). The average Injury Severity Score for all patients was 17.4 (range, 9-59). The average Injury Severity Score of the restrained patients was not statistically different from that of the unrestrained patients (p = 0.491). CONCLUSION: Although improvements in automotive safety features and restraint usage have occurred since previous reports appeared, there continues to be a high rate of severe injuries associated with traumatic hip dislocation that occur in motor vehicle collisions. We believe that all patients who sustain traumatic hip dislocation warrant a general surgery trauma evaluation to rule out any potential associated injuries.

Accidents, Traffic↗
PubMed1998

Consequences of transverse acetabular fracture malreduction on load transmission across the hip joint.

OBJECTIVE: To evaluate the biomechanical behavior of gap and step malreductions in a model of transverse acetabular fracture. DESIGN: Cadaver pelvis loading in simulated single-leg stance with intact acetabulum, after transverse acetabular fracture anatomically reduced, and after step and gap malreduction. Five transtectal transverse fractures; five juxtatectal transverse fractures. SETTING: Quasi-static loading of the hip with simulated abductor mechanism to physiologic loads with pressure-sensitive film interposed in the joint to determine contact area and contact pressure within the hip joint. MAIN OUTCOME MEASUREMENT: Hip joint contact parameters: contact area, peak and mean contact pressure, and load distribution. RESULTS: Step malreduction of the transtectal transverse fracture resulted in significantly increased peak contact pressures (20.5 megapascals) in the superior acetabular articular surface as opposed to the intact acetabulum (9.1 megapascals). Gap malreduction of transtectal transverse fracture and step and gap malreduction of juxtatectal fracture did not result in significantly increased contact pressures in the hip. CONCLUSION: Step malreduction of a transverse acetabular fracture in the superior articular surface results in abnormally high contact forces and may predispose to the development of posttraumatic arthritis.

Acetabulum↗
PubMed1997

Diagnosis and management of closed internal degloving injuries associated with pelvic and acetabular fractures: the Morel-Lavallée lesion.

Closed internal degloving is a significant soft-tissue injury associated with a pelvic trauma in which the subcutaneous tissue is torn away from the underlying fascia, creating a cavity filled with hematoma and liquefied fat. It commonly occurs over the greater trochanter but may also occur in the flank and lumbodorsal region. When this closed internal degloving occurs over the greater trochanter, it is known as a Morel-Lavallée lesion. We reviewed 24 patients who sustained a closed internal degloving injury. Cultures from the closed internal degloving injury were positive in 46% (11 of 24 cases). The incidence of positive cultures was not dependent on the time from injury to debridement. All wounds were treated by thorough debridement before or during pelvic or acetabular surgery. Three patients subsequently developed deep-bone infections, only one of whom had a positive culture at the initial debridement. One patient whose wound was primarily closed over suction drains developed a chronic deep soft-tissue infection requiring multiple debridements. The development of hematoma in the zone of operation reduces the safety of early operative intervention by increasing the risk of infection. An expanding hematoma in a closed internal degloving injury may further compromise the skin vascularity if not promptly drained. The injured soft tissues should be debrided early, either before or at the time of fracture fixation. The wound should be left open, and repeated surgical debridement of the injured tissue is recommended.

Acetabulum↗
PubMed1995

Total knee replacement including a modular distal femoral component in elderly patients with acute fracture or nonunion.

Distal femoral fracture or nonunion in elderly patients with osteopenic bone and coexisting gonarthrosis poses a difficult treatment challenge. Open reduction and internal fixation with or without the use of bone cement may not provide sufficient stabilization, requires a prolonged period of weightbearing restrictions, and does not address preexisting knee arthrosis. We report five patients, three with distal femoral nonunion, two with acute distal femoral fracture, and all with concomitant gonarthrosis treated with total knee replacement including a modular distal femoral component [distal femoral replacement (DFR)]. In this group of patients, modular DFR provided immediate pain relief and allowed early weightbearing and aggressive rehabilitation. We recommend this treatment modality in selected osteopenic elderly patients with difficult distal femoral reconstructive problems and coexisting gonarthrosis.

Aged↗
PubMed1995

Single plane and biplane external fixators for knee arthrodesis.

Thirty-six knee arthrodeses performed using an external fixator with an average followup of 48 months were reviewed retrospectively. A single plane fixator was used in 19 cases and a biplane fixator in 17 cases. The reasons for fusion included an infected total knee arthroplasty (21 cases), aseptic loosening of a total knee arthroplasty (9 cases), posttraumatic osteoarthritis (3 cases), and a neuropathic joint, an infected unicondylar knee arthroplasty, and a tuberculous joint (1 case each). A fusion was obtained after the initial procedure in 22 patients (61%). With additional procedures, a fusion was obtained eventually in 27 patients (75%). The fusion rate decreased with an increasing number of prior knee procedures. Single and biplane external fixator designs had similar initial fusion rates (single 58%, biplane 65%). Complications included 14 nonunions (5 fused with additional procedures), 6 pin tract infections, 5 delayed unions, 1 stress fracture through a pin site, and 1 persistent infection resulting in an above-knee amputation. Despite biomechanical advances in external fixator design, knee arthrodesis remains difficult to achieve in patients who have had multiple previous procedures, a failed total knee arthroplasty, or an infected total knee arthroplasty with significant bone loss.

Adult↗
PubMed1994

The use of the unreamed nail in tibial fractures with concomitant preoperative or intraoperative elevated compartment pressure or compartment syndrome.

Twelve patients with tibial shaft fractures and evidence of compartment syndrome or with documented elevated compartment pressures were treated with an unreamed locked intramedullary nail and a single-incision lateral four-compartment fasciotomy. There were six closed fractures and three grade I and three grade II open fractures. Ten fractures have achieved a solid union without shortening or significant angulation at an average follow-up of 8.1 months (range 4-26). Two patients were lost to follow-up. There were two delayed unions and one nonunion, all of which healed after additional treatment. Average time to tibial union was 5.8 months (range 2-24), with six fractures healing in < or = 4 months. One patient whose treatment was delayed > 12 h after his injury has a persistent neurologic deficit with a claw toe deformity. There were no superficial or deep infections. All patients obtained an excellent range of motion of the knee and ankle. Unreamed nailing of diaphyseal tibial fractures with an associated compartment syndrome provides optimal internal fixation while allowing excellent access for soft tissue care. We believe that the unreamed tibial nail, when combined with a single-incision, lateral, four-compartment fasciotomy, offers substantial advantage in the treatment of this injury, permitting optimal treatment of a difficult fracture and soft tissue injury.

Adult↗
PubMed1994

Pulmonary metastasis of benign giant cell tumor of bone. Six histologically confirmed cases, including one of spontaneous regression.

Benign giant cell tumor of bone, despite being classified as benign, has the unusual ability to metastasize. Metastasis of such a tumor has been thought to be rare, with only approximately 50 such cases having been reported. However, as awareness of the metastatic potential of these tumors has increased, and methods of detection have improved, metastasis of benign giant cell tumor has been increasingly recognized. Six patients with pulmonary metastasis of giant cell tumor have been treated at a Los Angeles hospital since 1980. This represents 9.1% of all patients treated for benign giant cell tumor of bone over the same period at this institution, a higher rate than that encountered in previously published series. The early detection and treatment of this tumor is important, because those with complete resection of tumor have the best prognosis. The nature of these pulmonary metastases remains unpredictable, however, as evidenced by two of the cases in this series: one of spontaneous regression, and another of death caused by pulmonary failure.

Adolescent↗
PubMed1993

Avulsion fracture of the coracoid associated with acromioclavicular dislocation.

A case report of an avulsion fracture of the coracoid process associated with a type III acromioclavicular dislocation is presented. The mechanism of injury and results of treatment in eighteen previously reported cases in the English-language literature are reviewed. Both operative and nonoperative treatment appear to offer equally favorable results. The treatment of this rare combined injury may follow the same guidelines used for treating isolated type III acromioclavicular dislocations.

Acromioclavicular Joint↗
PubMed1990

Biomechanical comparison of single- and double-pin fixation for acute slipped capital femoral epiphysis.

Biomechanics of pin fixation for acute slipped capital femoral epiphysis (SCFE) was studied in an in vitro immature canine model. Acute SCFE were created in 24 paired femurs. The paired specimens were pinned with either one or two pins and loaded to failure. Strength and stiffness of the paired limbs were expressed as percentages of the loads necessary to create the initial SCFE in the intact specimen. Strength and stiffness were equivalent statistically for the intact physis and the fractured physis fixed with two pins. Single pinning was only 83% as strong and 78% as stiff as the intact physeal plate. Double-pin fixation is recommended over single-pin fixation for acute SCFE. These data, however, should not be extrapolated to the clinical situation of fixation for chronic SCFE.

Animals↗
PubMedDate not supplied

Success of exchange reamed intramedullary nailing for femoral shaft nonunion or delayed union.

OBJECTIVES: To investigate the success of exchange reamed femoral nailing in the treatment of femoral nonunion after intramedullary (IM) nailing, and to analyze factors that may contribute to failure of exchange reamed femoral nailing. DESIGN: Retrospective consecutive clinical series. SETTING: Level I trauma center and tertiary university hospital. PATIENTS: Twenty-three patients were identified whose radiographs failed to show progression of healing for four months after treatment with a reamed IM femoral nail. Nineteen patients had undergone primary IM nailing of an acute femoral shaft fracture, one patient had been converted to an IM nail after initially being treated in an external fixator, and three patients had previously undergone an unsuccessful exchange reamed nailing. INTERVENTION: All patients were treated by exchange reamed femoral nailing. The diameter of the new nail was one to three millimeters larger than that of the previous nail (the majority were two millimeters larger). The intramedullary canal was overreamed by one millimeter more than the diameter of the nail. Most of the nails were statically locked, and care was taken to avoid distraction of the nonunion site by reverse impaction after distal interlocking was performed or by applying compression with a femoral distractor. MAIN OUTCOME MEASUREMENTS: Radiographic evaluation of union was determined by the presence of healing on at least three of four cortices. Factors reviewed included the patient's age, smoking history, mechanism of injury, associated injuries, whether the initial fracture was open or closed, the pattern and location of the fracture, the type of nonunion, the increase in nail diameter, whether the nail was dynamically or statically locked, and the results of any intraoperative cultures. RESULTS: Tobacco use was found to have a detrimental impact on the success of exchange reamed nailing. All eight of the nonsmokers healed after exchange reamed nailing, whereas only ten of the fifteen smokers (66.7 percent) healed after exchange reamed nailing. Overall, exchange reamed femoral nailing was successful in eighteen cases (78.3 percent). Three patients achieved union with additional procedures. Intramedullary cultures were positive in five cases; all of these achieved successful union. CONCLUSIONS: Exchange reamed nailing remains the treatment of choice for most femoral diaphyseal nonunions. Exchange reamed IM nailing has low morbidity, may obviate the need for additional bone grafting, and allows full weight-bearing and active rehabilitation. Tobacco use appears to have an adverse effect on nonunion healing after exchange reamed femoral nailing.

Adolescent↗
PubMedDate not supplied

Retained broken wound drains: a preventable complication.

A simple technique is described to avoid inadvertent suturing of a drain during wound closure. Drains that have been inadvertently sutured frequently break during removal, leaving a retained fragment in the wound. Use of the technique described herein will prevent this potentially avoidable complication.

Connective Tissue↗
PubMedDate not supplied

Olecranon fractures: treatment options.

Fractures of the olecranon process of the ulna typically occur as a result of a motor-vehicle or motorcycle accident, a fall, or assault. Nondisplaced fractures can be treated with a short period of immobilization followed by gradually increasing range of motion. Open reduction and internal fixation is the standard treatment for displaced intra-articular fractures. Stable internal fixation with figure-of-eight tension-band wire fixation for simple transverse fractures allows early motion to minimize stiffness. Use of two knots produces symmetric tension at the fracture site and provides more rigid fixation than a single knot. Care should be taken to ensure that the tension-band wire and the proximal ends of the Kirschner wires are positioned deep to the triceps fibers to prevent wire migration. If the anterior cortex is engaged, overpenetration of the wires into the soft tissues should be avoided. Plate fixation is appropriate for severely comminuted fractures, distal fractures involving the coronoid process, oblique fractures distal to the midpoint of the trochlear notch, Monteggia fracture-dislocations of the elbow, and nonunions. For comminuted fractures and nonunions, a dorsally applied limited-contact dynamic-compression plate with supplemental bone graft should be utilized to support comminuted depressed articular fragments. A one-third tubular hook-plate can be used for fractures with a small proximal fragment for which additional fixation of the olecranon tip is desired. Fragment excision and triceps advancement is appropriate in selected cases in which open reduction seems unlikely to be successful, such as in osteoporotic elderly patients with severely comminuted fractures.

Biomechanical Phenomena↗