Biomedical subjects

Gerard K Jeong

Publications and source records attributed to Gerard K Jeong.

8 recordsLinked to original sources

PubMed2006

"Floating total knee": ipsilateral periprosthetic fractures of the distal femur and proximal tibia after total knee arthroplasty.

UNLABELLED: Currently, there are more than 300000 primary total knee arthroplasty (TKA) performed annually in the United States. It is estimated that 0.3% to 2.5% of these patients will sustain a periprosthetic fracture in association with a TKA [Haidukewych GJ, Jacofsky DJ, Hanssen AD. Treatment of periprosthetic fractures around a total knee arthroplasty. J Knee Surg 2003;16:111]. The first report of a periprosthetic fracture involving a TKA occurred in 1977 [Callaghan JJ. Periprosthetic fractures of the acetabulum during and following total hip arthroplasty. Instr Course Lect 1998;47:231]. The majority of periprosthetic fractures associated with a TKA are distal femoral fractures [Berry D. EPIDEMIOLOGY: hip and knee. In: Callaghan J, Duncan C, editors. Periprosthetic fractures after major joint replacement. Philadelphia: WB Saunders; 1999. p. 183]. Periprosthetic tibial fractures are rare and usually involve the medial tibial plateau in the presence of a loose component [Rand JA, Coventry MB. Stress fractures after total knee arthroplasty. J Bone Joint Surg Am 1980;62:226, Hanssen AD, Stuart MJ]. Treatment of periprosthetic tibial fractures. Clin Orthop 2000; p. 91]. The following case report describes the management of simultaneous ipsilateral distal femoral and proximal tibial periprosthetic fractures associated with a TKA. The patient was informed that data concerning the case would be submitted for publication. To our knowledge, this "floating total knee" injury has not been previously reported.

Accidental Falls↗

PubMed2006

Semiconstrained knee arthroplasty in the setting of a chronic knee dislocation: a case report.

We present the case of a 27-month chronic knee dislocation treated with a semiconstrained, stemmed total knee arthroplasty. The patient was neurovascularly intact preoperatively but had severe functional limitations caused by pain, stiffness, and instability. At 2-year follow-up, the patient remains pain-free with functional range of motion and the ability to ambulate without complication. This case report represents the longest-cited chronic knee dislocation treated with a reconstructive procedure.

Arthroplasty, Replacement, Knee↗

PubMed2006

A biomechanical comparison of two volar locked plates in a dorsally unstable distal radius fracture model.

BACKGROUND: This study compares the biomechanical stability of two volar locked plate systems for fixation of unstable, extra-articular distal radius fractures. METHODS: In six matched pairs of fresh frozen cadaveric specimens, a simulated unstable, extra-articular distal radius fracture was created. The fractures were stabilized with one of two types of volar locked plates. Specimens were axially loaded at five different positions: central, volar, dorsal, radial, and ulnar. Initial (precyclic loading) stiffness of each locked plate system was calculated. Each specimen was then loaded for 5,000 cycles with an 80 N central load. Finally, specimens were axially loaded at the same five positions to calculate the postcyclic loading stiffness of each volar locked plate system. Main outcome measurements were precyclic loading stiffness, postcyclic loading stiffness, maintenance of stiffness after cyclic loading, and amount of fracture displacement between the two volar locked plate systems. RESULTS: There were no differences in maintenance of stiffness and fracture displacement following cyclical loading between the two volar plate systems. After cyclic loading, the distal volar radius (DVR) locked plate was significantly stiffer than the Synthes volar locked plate in volar loading only (p < 0.01). CONCLUSION: Materials properties and design differences between these systems did not provide enough biomechanical difference to support use of either implant over the other. With this in vitro model, both implants provided adequate stability to resist physiologic loads expected during therapy in the initial postoperative period.

Adult↗

PubMed2005

A biomechanical comparison of a dorsal 3.5-mm T-plate and a volar fixed-angle plate in a model of dorsally unstable distal radius fractures.

OBJECTIVES: To compare the biomechanical stability of internal fixation of extra-articular, dorsally unstable distal radius fractures fixed by 1 of 2 methods, either a standard dorsal nonlocked T-plate or a volar locked fixed-angle plate. DESIGN: Biomechanical cadaveric study. SETTING: Biomechanical testing laboratory. INTERVENTION: In 6 matched pairs of fresh-frozen cadaveric specimens, a simulated unstable extra-articular distal radius fracture was created. The fractures were stabilized with either a dorsal 3.5-mm stainless steel T-plate or a titanium locked volar fixed-angle plate. Specimens were axially loaded at 5 points (centrally, volarly, dorsally, radially, and ulnarly) and then cyclically loaded for 5000 cycles with an 80 N central load. Postcyclical loading, specimens were once again axially loaded at the 5 points. MAIN OUTCOME MEASURES: Initial fixation stiffness and stiffness after midaxial cyclical loading was compared at the 5 points. RESULTS: With the volar locked fixed-angle plate, fixation was significantly stiffer than with the dorsal nonlocked T-plate for ulnar and volar loading in single-cycle testing. After cyclic loading, the locked volar fixed-angle plate maintained more of its initial stiffness than the dorsal nonlocked T-plate. The dorsal 3.5-mm stainless steel T-plate's stiffness when dorsally loaded significantly decreased after cyclical loading. CONCLUSIONS: The volar locked fixed-angle plate maintained a greater percentage of its initial stiffness after cyclic loading compared to the dorsal nonlocked plate. Also, the volar locked plate was stiffer than the dorsal nonlocked plate for all loading configurations tested except when subjected to a dorsally applied eccentric load.

Adult↗

PubMed2004

Spinal disorders in the elderly.

As life expectancies increase, the geriatric population will increase, and the treatment of spinal diseases in the elderly will become even more commonplace. Treatment of spinal disorders in the geriatric patient population is a difficult challenge and involves numerous surgical, medical, and social issues. This review will provide an overview of the various spinal disorders particular to the geriatric patient population and will highlight certain concepts critical in the treatment of the spine in the geriatric population. Multiple factors, including poor tolerance of immobilization, medical comorbidities, use of multiple chronic medications, poor nutritional status, inadequate bone stock, and poor bone quality limit rigorous adherence to one treatment algorithm. These issues should be taken into consideration when formulating an individualized treatment plan that emphasizes early mobilization and functional rehabilitation. Goals, expectations, and surgical indications should be realistic and often will differ from those for a younger, healthier population. The use of a multidisciplinary approach will increase the likelihood of a successful treatment outcome and decrease the likelihood of potential complications.

Aged↗

PubMed2004

An evaluation of two scoring systems to predict instability in fractures of the distal radius.

BACKGROUND: Various scoring scales have been introduced in the management of patients with multiple injuries and lower extremity injuries. Two scoring systems have been introduced to predict instability in distal radius fractures. The purpose of this investigation was to evaluate the accuracy of these two models in predicting instability. METHODS: A prospective study of 105 consecutive patients sustaining unilateral closed distal radius fractures was performed. Two scoring systems--the MacKenney formula and the Adolphson formula--were used to calculate the probability of fracture instability on the basis of initial presentation and injury films. The predicted probability of instability calculated from both models was then compared with actual results of instability on the basis of specific radiographic criteria at follow-up. RESULTS: Final follow-up information was available on 80 patients. There were 44 unstable fractures and 36 stable fractures at final follow-up. Using the MacKenney formula, of the 38 fractures predicted to have a low probability of instability (Pinstability < 30%), 18 (47.4%) were found to be unstable. Using the Adolphson formula, of the 28 fractures predicted to have a low probability of instability (Pstability > 70%), 14 (50%) were actually unstable. CONCLUSION: Both scoring systems were found to underestimate the degree of fracture instability and to have a negative predictive value between 47 and 50% in a prospective series of patients. In fractures predicted to have a low probability of instability in both models, we found a poor correlation between predicted instability and actual instability. Our results demonstrate the limitations of two scoring systems in predicting fracture stability and in making clinical decisions on the basis of their results.

Adult↗

PubMedDate not supplied

Lumbar intervertebral disc cyst as a cause of radiculopathy.

BACKGROUND CONTEXT: Lumbar radiculopathy is commonly caused by degenerative conditions such as a herniated disc or lumbar spinal stenosis. Less common etiologies include intraspinal extradural masses such as synovial cysts and gas-containing ganglion cysts. Intraspinal extradural cysts that communicate with the intervertebral disc are a rare entity and thus, an uncommon cause of lumbar radiculopathy. There are only ten cases of an intervertebral disc cyst reported in the literature. PURPOSE: To document the first reported case of an intervertebral disc cyst in North America. Two series of Japanese patients with intervertebral disc cyst confirmed radiographically and intraoperatively have recently been reported. STUDY DESIGN: A case report of an intervertebral disc cyst at L4-5 causing an L5 radiculopathy. OUTCOME MEASURES: Japanese Orthopaedic Association score for low back pain. METHODS: The patient and the authors involved in the patient's management were interviewed. All medical records, radiographic imaging studies, intraoperative findings, and pertinent literature were also reviewed. RESULTS: Preoperative magnetic resonance imaging (MRI) scan demonstrated a well-localized cyst compressing the ventral aspect of the thecal sac at L4-L5. Discography and subsequent computed tomographic (CT) scanning demonstrated the cyst communicating with an intervertebral disc herniation via an annular rupture. Decompressive discectomy and surgical excision of the disc cyst from the spinal canal resulted in complete recovery and resolution of the preoperative radiculopathy. Clinical improvement was documented using the JOA scoring system. Patient's preoperative score was 4/15, and postoperative score was 15/15. CONCLUSION: Although exceedingly rare, an intervertebral disc cyst should remain in the differential diagnosis of any extradural intraspinal mass ventral to the thecal sac. Diagnosis of an intervertebral disc cyst requires recognition of this uncommon entity and a high index of suspicion. Discography and post-discography computerized tomography (CT) scan confirm the diagnosis. Operative treatment includes decompression, and excision of the cyst and is reserved only for cases in which the cyst results in clinical symptoms unresponsive to nonoperative management.

Adult↗

PubMedDate not supplied

Total hip arthroplasty in sickle cell hemoglobinopathies.

Advances in medical treatment have led to improved life expectancy in patients with sickle cell hemoglobinopathies. Improved life expectancy has, in turn, led to an increasing number of patients with osteonecrosis requiring total hip arthroplasty. Patient evaluation begins with understanding the extent of the disease process and the patient's musculoskeletal manifestations (ie, pyogenic infection, marrow hyperplasia, osteonecrosis). A multidisciplinary approach to implementing effective preoperative treatment strategies increases the likelihood of a successful surgical outcome. Intraoperatively, consideration of bone stock, bone quality, and method of component fixation may help minimize the risk of eccentric reaming, perforation or fracture of either the acetabulum or the femur, and loosening. The optimal mode of acetabular and femoral fixation in these patients has not been conclusively determined, but recent results of cementless total hip arthroplasty have been encouraging. Although patients with sickle cell disease are at increased risk of medical and surgical complications, total hip arthroplasty in the appropriately selected patient can provide significant pain relief, restoration of function, and patient satisfaction.

Anemia, Sickle Cell↗