Biomedical subjects
Publications and source records attributed to Kenneth J Koval.
Instrument wear and tear, mishandling, and abuse can lead to instrument damage, particularly closely machined mating surfaces, which then prevents them from functioning properly. Simple refinishing of these damaged surfaces often resolves these problems. The electrocautery scratch pad can be an excellent means of rapidly refinishing damaged instruments.
SUMMARY: We present the previously unreported complication of symptomatic heterotopic ossification of the quadriceps following placement of a large-diameter Steinmann pin for the purpose of temporary skeletal traction. Following the development of distal quadriceps heterotopic bone formation in three patients, we conducted a comprehensive search of the literature using the Medline database from 1966 to the present. A variety of publications, including review articles, case reports, and randomized prospective studies, were used for the literature review. This potential complication should be considered when using a large-diameter Steinmann pin in the distal femur for skeletal traction.
OBJECTIVES: To describe the epidemiology of perioperative anemia in patients with hip fracture and assess the relationship between the hemoglobin measurements and clinical outcomes. DESIGN: Prospective observational cohort study. SETTING: Four university and community teaching hospitals. PATIENTS: A consecutive cohort of 550 patients who underwent surgery for hip fracture and survived to discharge from August 1997 and August 1998 were evaluated and followed prospectively. MAIN OUTCOME MEASURES: Deaths, readmissions and Functional Independence Motor mobility scores within 60 days of discharge. RESULTS: Anemia (defined as hemoglobin <12.0 g/dL) was present in 40.4% of patients on admission, 45.6% at the presurgery nadir, 93.0% at the postsurgery nadir, and 84.6% near discharge. The mean drop in hemoglobin after surgery was 2.8 +/- 1.6 g/dL. In multivariate analyses, higher hemoglobin levels on admission were associated with shorter lengths of hospital stay and lower odds of death and readmission even after controlling for a broad range of prefracture patient characteristics, clinical status on discharge, and use of blood transfusion. Admission and preoperative anemia was not associated with risk-adjusted Functional Independence Motor mobility scores. In multivariable analyses, higher postoperative hemoglobin was associated with shorter length of stay and lower readmission rates, but did not effect rates of death or Functional Independence Motor mobility scores. CONCLUSIONS: Substantial declines in hemoglobin were common in patients with hip fracture. Higher preoperative hemoglobin was associated with shorter length of stay and lower odds of death and readmission within 60 days of discharge. Postoperative hemoglobin was also related to length of stay and readmission rates.
OBJECTIVES: The anterior curvature of the femur affects intramedullary nail insertion, revision prosthesis design, and the biomechanics of the proximal femur. Two previous studies, using small numbers of femurs, determined femoral curvature and showed that it was significantly greater than that of the several intramedullary nails they evaluated. In this study, the curvature of 948 femurs (474 matched pairs) was determined and compared with current intramedullary nails. The correlation of femoral curvature to age, gender, femoral size, and race was also evaluated. SETTING: Museum skeletal collections and a hospital biomechanics laboratory. METHODS: The curvature of 892 femurs (446) from the skeletal collections of 2 museums was measured by processing the digital images of the femurs with a computer curve-fitting program. Fifty-six additional, embalmed femurs (28 pairs) from our collection were also digitally imaged and then radiographed and their medullary curvatures similarly determined for comparison. Curvatures of 8 current antegrade intramedullary nails and 3 long-stemmed femoral hip prostheses were obtained from manufacturers and confirmed by measurements from their templates after digitization. RESULTS: We found the average femoral anterior radius of curvature was 120 cm (+/- 36 cm). There was no effect of age on femoral curvature nor was there a correlation between femoral width or femoral length to curvature. Black donor femurs had less curvature than white donor femurs (P < 0.001). There was close correlation (r = 0.967) between the femoral curvatures determined from the digital images and the radiographs. Radii of curvature of the intramedullary nails ranged from 186 to 300 cm (eg, straighter than the femurs). CONCLUSIONS: There was a large mismatch between the curvature of some current antegrade intramedullary nails and the average femur. Although this is only 1 factor affecting nail insertion, the mismatch warrants a reappraisal of these intramedullary nail designs. CLINICAL RELEVANCE: Because ease of intramedullary nail insertion and possibility of cortical comminution are determined by a number of factors including insertion point and fracture location, it appears that a decrease in radii of curvature (less straight) of current nail designs is warranted, particularly for those larger diameter nails designed for hip fracture stabilization that have greater rigidity due to design or material.
OBJECTIVE: To review the biomechanical principles that guide fracture fixation with plates and screws; specifically to compare and contrast the function and roles of conventional unlocked plates to locked plates in fracture fixation. We review basic plate and screw function, discuss the design rationale for the new implants, and examine the biomechanical evidence that supports the use of such implants. DATA SOURCES: Systematic review of the per reviewed English language orthopaedic literature listed on PubMed (National Library of Medicine online service). STUDY SELECTION: Papers selected for this review were drawn from peer review orthopaedic journals. All selected papers specifically discussed plate and screw biomechanics with regard to fracture fixation. PubMed search terms were: plates and screws, biomechanics, locked plates, PC-Fix, LISS, LCP, MIPO, and fracture fixation. DATA SYNTHESIS: The following topics are discussed: plate and screw function-neutralization plates and buttress plates, bridge plates; fracture stability-specifically how this effects gap strain and fracture union, conventional plate biomechanics, and locking plate biomechanics. CONCLUSIONS: Locked plates and conventional plates rely on completely different mechanical principles to provide fracture fixation and in so doing they provide different biological environments for healing. Locked plates may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Conventional plates may continue to be the fixation method of choice for periarticular fractures which demand perfect anatomical reduction and to certain types of nonunions which require increased stability for union.
Nine-hundred twenty-one community-dwelling patients 65 years of age or older, who sustained an operatively treated hip fracture from July 1, 1987 to June 30, 1998 were followed up for the development of postoperative delirium. The outcomes examined in the current study were postoperative complication rates, in-hospital mortality, hospital length of stay, hospital discharge status, 1-year mortality rate, place of residence, recovery of ambulatory ability, and activities of daily living 1 year after surgery. Forty-seven (5.1%) patients were diagnosed with postoperative delirium. Patients who had delirium develop were more likely to be male, have a history of mild dementia, and have had surgery under general anesthesia. Patients who had postoperative delirium develop had a significantly longer length of hospitalization. They also had significantly higher rates of mortality at 1 year, were less likely to recover their prefracture level of ambulation, and were more likely to show a decline in level of independence in basic activities of daily living at the 1-year followup. There was no difference in the rate of postoperative complications, in-hospital mortality, discharge residence, and recovery of instrumental activities of daily living at 1 year.
Hip fractures are common injuries in the elderly and are associated with considerable morbidity and mortality. Although technical advances in the treatment of the elderly have resulted in improved fracture fixation and surgical outcomes, clinical pathways have been developed to further improve patient outcome while shortening hospital length of stay after hip fracture. We describe the clinical pathway used since 1990 at the Hospital for Joint Diseases. The outcomes of 747 patients treated before 1990 were compared with outcomes of 318 patients treated at our hospital after initiation of the clinical pathway. Use of the clinical pathway was associated with significant decreases in the acute care hospital length of stay, in-hospital mortality, and 1-year mortality.
A review of prospectively collected data was done to compare functional outcomes and mortality among patients with different hip fracture types. Five hundred thirty-seven elderly patients who sustained a hip fracture were followed up prospectively. Orthopaedists blinded to treatment and outcome radiographically classified the fractures as either: (1) nondisplaced or impacted femoral neck; (2) displaced femoral neck; (3) stable intertrochanteric; or (4) unstable intertrochanteric fracture. Functional independence measure scores were calculated for preinjury function and at 2- and 6- month follow-ups. Comorbidities, operative details, postoperative complications, and deaths were recorded. Six-month mortality was lowest for patients with nondisplaced femoral neck fractures (5.7%) and highest for patients with displaced femoral neck fractures (15.8%), but multivariate analysis only identified preinjury function as an independent predictor of mortality. All preinjury and followup functional independence measure scores were greatest for patients with nondisplaced femoral neck fractures and least for patients with unstable intertrochanteric fractures. However, multivariate analysis identified only patient age and preinjury functional independence measure scores as independent predictors of functional outcome. These data show differences in mortality and functional outcomes among fracture types that can be attributed to differences in functional status before injury.
BACKGROUND: The lateral trochanteric support plate (LSP) was developed to prevent excessive sliding of unstable intertrochanteric femur fractures fixed with a sliding hip screw (SHS). This study compared the fracture stability and screw sliding characteristics of unstable intertrochanteric femur fractures fixed with either an SHS and LSP or an Intramedullary Hip Screw (IMHS). METHODS: Six matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric femur fractures were stabilized with either an IMHS or a 135-degree SHS with an attached LSP. Inferior and lateral head displacements and lag screw sliding distances were measured for applied static loads of 750 N, before and after cycling. RESULTS: Four-part unstable intertrochanteric femur fractures showed comparable screw sliding characteristics and stability whether instrumented with an SHS and LSP or an IMHS. CONCLUSION: A sliding hip screw with an attached lateral support plate provides stability and ability to resist medial displacement of the femoral shaft similar to that seen with the IMHS.
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.
BACKGROUND: Bicondylar tibial plateau fractures are complex injuries, historically associated with high complication rates. The purpose of this study was: 1) to evaluate the clinical use L.I.S.S plating system for stabilization of bicondylar tibial plateau fractures. 2) To compare the biomechanics of this plating system with a double plate construct. METHODS AND MATERIALS: Thirty-eight patients who sustained a complex tibial plateau fracture (OTA type 41C) at one of three level-one trauma centers were stabilized using the Less Invasive Stabilization System (L.I.S.S.). The cohort of patients was evaluated clinically and radiographically for outcomes at a mean 15 months. In phase 2 of this study a model of a bicondylar tibial plateau fractures was made in six matched pairs of embalmed, human tibia and randomized to fixation with either a L.I.S.S plate or a standard double plate construct. The tibias were then subjected to an axial cyclic load of 500N for 10 cycles (3Hz) to approximate 2 months in vivo and displacements measured. RESULTS: Thirty-six of /38 (95%) patients united at 4 months after surgery with no loss of fixation nor infection. Two patients underwent prophylactic autogenous bone grafting for bone loss and united by 3 months postgrafting. Significant loss of knee range of motion (<90) was seen in five patients.Biomechanically, no differences in permanent inferior displacement of the medial fragment were found in initial axial loading and after 10 cycles between the two plate constructs. However, when loaded to 500N the L.I.S.S plate construct demonstrated almost twice the displacement of the medial fragment compared with the dual plate construct. No specimen lost fixation during cycling. CONCLUSION: The L.I.S.S plating system provides stable fixation of complex bicondylar tibial plateau fractures allowing early range of knee motion with favorable clinical results.
OBJECTIVES: To examine the relationship between early physical therapy (PT), later therapy, and mobility 2 and 6 months after hip fracture. DESIGN: Prospective, multisite observational study. SETTING: Four hospitals in the New York City area. PARTICIPANTS: Four hundred forty-three hospitalized older patients discharged after surgery for hip fracture in 1997-98. MEASUREMENTS: Patient demographics, fracture type, comorbidities, dementia, number of new impairments at discharge, amount of PT between day of surgery and postoperative day (POD) 3, amount of therapy between POD4 and 8 weeks later, and prefracture, 2-, and 6-month mobility measured using the Functional Independence Measure. RESULTS: More PT immediately after hip fracture surgery was associated with significantly better locomotion 2 months later. Each additional session from the day of surgery through POD3 was associated with an increase of 0.4 points (P=.032) on the 14-point locomotion scale, but the positive relationship between early PT and mobility was attenuated by 6 months postfracture. There was no association between later therapy and 2- or 6-month mobility. CONCLUSION: PT immediately after hip fracture surgery is beneficial. The effects of later therapy on mobility were difficult to assess because of limitations of the data. Well-designed randomized, controlled trials of the effect of varying schedules and amounts of therapy on functional status after hip fracture would be informative.
BACKGROUND: The expanding role of industrial support in biomedical research has resulted in both substantial interest and controversy in recent years. Our hypothesis was that, from 1985 to 2002, the role of industrial support in orthopaedic research increased, as documented by the research presented at the annual meetings of the American Academy of Orthopaedic Surgeons. METHODS: We analyzed the frequency and types of self-reported conflicts of interest for all presentations at the annual meetings of the American Academy of Orthopaedic Surgeons in 1985, 1988, 1992, 1997, 1999, and 2002. Conflicts of interest were recorded directly from the final program for each meeting analyzed. The analysis focused on the scientific presentations, Instructional Course Lectures, symposia, poster exhibits, and scientific exhibits. Information about specific types of support received by authors was first required in 1988. RESULTS: The incidence of conflicts of interest increased from 3% in 1985 to 39% in 2002 for scientific papers (p < 0.001); from 10% to 74%, respectively, for symposia (p < 0.001); from 22% to 60% for Instructional Course Lectures (p < 0.001); from 10% to 60% for scientific exhibits (p < 0.001); and from 9% in 1992 to 14% in 2002 for posters (p < 0.001). For presentations of all types, the incidence increased from 10% to 32% (p < 0.001). The types of conflict of interest also changed significantly from 1999 to 2002. In 1999, 73% of conflicts were documented as support directed to institutions and 27%, as support to individuals; in 2002, 57% were reported as support directed to institutions and 43%, as support to individuals (p < 0.01). CONCLUSIONS: The role of industrial support of orthopaedic research increased significantly between 1985 and 2002, as evidenced by the increase in the self-reported conflicts of interest for all types of presentations at the annual meetings of the American Academy of Orthopaedic Surgeons. In addition, the support directed to individuals, in contrast to that directed to institutions, increased significantly.
BACKGROUND: The purpose of this study was to confirm the prevalence of medial ankle widening among patients with an isolated fibular fracture and to determine the functional outcome of nonoperative treatment despite a diagnosis of a supination-external rotation stage-IV injury based on stress radiography. METHODS: One hundred and one patients with evidence of an isolated fibular fracture and an intact mortise seen on a standard ankle trauma radiograph series were evaluated with stress radiographs. Clinical signs were recorded at the time of presentation. A positive stress test was defined as > or =4 mm of widening of the medial clear space. Patients with a negative stress test were treated nonoperatively, those with a positive stress test and clinical signs of medial injury were treated surgically, and those with a positive stress test and no signs of medial injury were treated according to the preference of the surgeon and patient. The patients were followed prospectively with radiographs and ankle outcome scores. RESULTS: Sixty-six (65%) of the 101 patients had a positive stress radiograph. Thirty-six of them had signs of medial injury, and thirty had no medial injury. With regard to predicting a positive stress radiograph, medial tenderness had a sensitivity of 56% and a specificity of 80%, swelling had a sensitivity of 55% and a specificity of 71%, and ecchymosis had a sensitivity of 26% and a specificity of 91%. Of the subset of patients without signs of medial injury, twenty were treated nonoperatively (group I) and ten were treated operatively (group II). Two of the twenty patients in group I had evidence of persistent widening of the medial clear space at the time of the latest follow-up (mean, 7.4 months); only one of those patients was symptomatic. The average American Orthopaedic Foot and Ankle Society (AOFAS) score was 94 points in group I and 93 points in group II. CONCLUSIONS: We found a high rate of positive stress radiographs for patients who presented with an isolated fibular fracture and an intact ankle mortise on the initial radiographs. Medial tenderness, swelling, and ecchymosis were not sensitive with regard to predicting widening of the medial clear space on stress radiographs. All of the patients with a positive stress radiograph and no clinical symptoms who were treated without surgery had a good or excellent clinical result.
The accuracy of measuring angulation of stable proximal humerus fractures using the axillary lateral projection was investigated. A closing wedge osteotomy with apex anterior angulation was performed on two cadaveric humeri to simulate a stable surgical neck fracture. One specimen was fixed at 30 degrees angulation and the other at 55 degrees. Axillary radiographs were taken with each specimen articulating with the glenoid of a cadaveric scapula. The humerus was held in neutral rotation. Abduction was set at 30 degrees, 60 degrees, and 90 degrees. In each position of abduction, an axillary lateral radiograph was taken in 30 degrees forward flexion, neutral, and 30 degrees extension to simulate various arm positions. A total of nine radiographs were taken for each specimen. The axillary view is not accurate for measurement of proximal humerus angulation at the arm positions commonly encountered in the trauma setting.
A tape blister, a skin excoriation that occurs under the taped portion of surgical bandages, can be a source of postoperative morbidity. Tape blisters are caused by the separation of the epidermis from the dermis at the dermal-epidermal junction. Tape resistant to stretching contributes to blister formation because of the concentration of forces at the ends of the tape. Although tape blisters are a pervasive clinical problem, their incidence after hip surgery has rarely been reported in the orthopedic literature. Therefore, we retrospectively reviewed a consecutive series of patients with hip fractures to determine the incidence of tape blisters at our institution. One hundred three patients were included in the study. Tape-related injuries occurred in 22 patients (21.4%). Patient age, patient sex, number of medical comorbidities, smoking history, nutritional status, and type of surgery were not statistically significantly associated with risk for developing tape blisters.
The purpose of this study was to determine the effect of the last hemoglobin level before patient discharge on outcome after hip fracture. We retrospectively reviewed data prospectively collected from July 1987 to December 1997 on 844 community-dwelling patients 65 or older who had sustained an operatively treated femoral neck or intertrochanteric fracture. Women with postoperative hemoglobin levels below 12.0 g/dL and men with levels below 13.0 g/dL were classified as having anemia. The main outcome measures were mortality, return to ambulatory ability, and return to activities of daily living at 3, 6, and 12 months. Hemoglobin data were available for 714 patients (85%). At time of last hemoglobin level measurement before discharge, 643 (90.1%) of the 714 patients were classified as having anemia. Patients who had sustained a femoral neck fracture that was treated with internal fixation were less likely to have anemia than were patients who had sustained a femoral neck fracture that was treated with hemiarthroplasty and patients who had sustained an intertrochanteric fracture (P < .001). Patients with anemia at the last discharge were not at increased risk for adverse outcomes at 3, 6, or 12 months compared with patients who did not have anemia.
BACKGROUND: Hip fracture is associated with significant mortality and disability. Patients who are discharged from the hospital with active clinical problems may have worse outcomes than those patients without active clinical problems. OBJECTIVE: To assess the frequency and impact of clinical problems at discharge on clinical and functional hip fracture outcomes. METHODS: Detailed clinical data were collected from 559 patients in a prospective, multicenter observational cohort study. Active clinical issues (ACIs) on discharge included the following: temperature of 38.3 degrees C or higher, heart rate of more than 100/min or less than 60/min, systolic blood pressure higher than 180 mm Hg or lower than 90 mm Hg, diastolic blood pressure higher than 110 mm Hg or lower than 60 mm Hg, respiratory rate of more than 24/min, oxygen saturation of less than 90%, altered mental status, no oral intake, shortness of breath, chest pain, arrhythmias, or wound infection. New impairments (NIs) included bowel and bladder incontinence, inability to get out of bed, and decubitus ulcer. Outcomes were deaths, readmissions, and functional mobility 60 days after discharge. RESULTS: Overall, 94 patients (16.8%) had 1 or more ACIs, and 229 (41.0%) had 1 or more NIs on discharge. Both ACIs and NIs on discharge were associated with increased risk-adjusted rates of death (odds ratio, 1.8; 95% confidence interval, 1.2-2.8) or readmission (odds ratio, 1.7; 95% confidence interval, 1.2-2.3). The NIs on discharge were also associated with worse functional mobility (P<.004). These relationships persisted in multivariate analyses that controlled for a previously validated, hip fracture-specific risk adjustment measure. CONCLUSIONS: Clinicians should consider information about ACIs and NIs when deciding readiness for discharge and planning post-acute care.