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Biomedical subjects

Bruce D Beynnon

Publications and source records attributed to Bruce D Beynnon.

At least 37 records · Page 2Linked to original sources
PubMed2005

Efficacy of plantar loading parameters during gait in terms of reliability, variability, effect of gender and relationship between contact area and plantar pressure.

BACKGROUND: The purpose of this study was to determine plantar pressure and contact areas of the foot inside the athletic shoe during activity. The objectives were to determine if plantar pressure and contact area measurements collected on multiple trials from the same subject were reliable, to determine the variability of measurements between subjects as compared to that found between steps within a single subject, to determine the relationship between contact area and plantar pressure, and to ascertain whether there were any systematic gender differences in these measurements. METHODS: Sixteen healthy adults volunteered for participation in the first part of the study that was designed to determine reliability and variability of the testing methodology. A separate group of fifty healthy high school and collegiate athletes participating in soccer, field hockey, basketball, and lacrosse comprised the second part of the study that was designed to investigate gender differences in terms of normalized midfoot plantar pressure and contact area, and the interrelationship between the two measurements. Data were collected during the midstance phase of gait, using the Pedar in-shoe measurement system (Novel GMBH, St. Paul, MN). Athletes wore their own athletic shoes and performed walking trials on a surface similar to that used in their sport. The foot was divided into four regions based on radiographic measurements. RESULTS: The midfoot region demonstrated excellent reliability across multiple trials of the same subject in contact area and plantar pressure, and the variability between steps within a single subject was small when compared to that between subjects. Normalized midfoot contact area and plantar pressure values were highly correlated with r values of 0.862 on the left foot and .912 on the right foot. No significant differences were found in normalized midfoot contact area or plantar pressure values between males and females. CONCLUSIONS: The Pedar in-shoe pressure measurement system can be used reliably to quantify contact area and plantar pressure beneath the midfoot region during the midstance phase of gait. This measurement technique can now be used in risk factor studies designed to identify individuals at risk for injury to the foot, ankle, and other lower extremity structures.

Adult↗
PubMed2004

Efforts to improve cementless femoral stems in THR: 2- to 5-year follow-up of a high-offset femoral stem with distal stem modification (Secur-Fit Plus).

A retrospective review of 81 sequential primary total hip arthroplasties using a cementless, high-offset femoral stem was performed. Follow-up was 24 to 60 months. The average age at the time of surgery was 54 years. The femoral bone types were: 36% Dorr A, 51% Dorr B, and 13% Dorr C. The mean postoperative Harris Hip Score was 95. The mean postoperative Oxford score was 17. Eighty-five percent had no clinical leg-length difference. All stems were radiographically stable. The stem features of hydroxyapatite coating on a rough circumferential titanium arc-deposit proximal surface in conjunction with distal flutes seem to provide immediate stability, making this implant clinically versatile. Potential benefits of increased offset include improved joint stability and avoidance of leg lengthening.

Arthroplasty, Replacement, Hip↗
PubMed2004

Femoral component sizing in total knee arthroplasty: size matched resection versus flexion space balancing.

Generally, 2 different methods are used to select femoral size. These can be termed "size-matched resection" and "flexion-space balancing." The purpose of this paper is to compare these 2 methods during 50 sequential total knee arthroplasty surgeries. The flexion-space-balancing method led to a smaller size selection than the size-matched-resection method in 28 (56%) knees. In the remaining 22 knees, the measurement methods led to the selection of the same size femoral component. The difference in measurement methods was significant (P<.05). The preoperative varus knees were more sensitive to the differences in measurement methods than the valgus knees (P<.05). A flexion space that is too small may adversely affect the clinical outcome of knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2004

Tibiofemoral kinematic analysis of kneeling after total knee arthroplasty.

Some surgeons warn against kneeling after total knee arthroplasty (TKA), because limited clinical data exist. We describe the tibiofemoral contact position of TKA components during kneeling in vivo. Ten posterior-substituting (PS) and 10 cruciate-retaining (CR) designs were examined using a radiographic image-matching technique. Movement from standing to kneeling at 90 degrees produced different responses. CR knees translated anteriorly (medial, 4 +/- 4 mm; lateral, 2 +/- 6 mm). PS knees underwent little posterior translation (medial, 0.2 +/- 3 mm; lateral, 1 +/- 4 mm). Movement from 90 degrees to maximum flexion produced femoral posterior translation (CR medial, 5 +/- 4 mm; CR lateral, 5 +/- 4 mm; PS medial, 6 +/- 4 mm; PS lateral, 6 +/- 3 mm). The relationship between tibiofemoral contact position and flexion angle was more variable for CR (r2=.38) than for PS (r2=.64). Knee kinematics was similar to other deep-flexion weight-bearing activities.

Aged↗
PubMed2004

In vivo measurement of ligament/tendon strains and forces: a review.

Accurate and precise measurements of ligament and tendon biomechanics in living humans are needed to better understand function and injury and to optimize treatment. The complex structure and loadings of these internal soft tissues makes in vivo measurements difficult to obtain. A noninvasive method that can be used in the field during normal unrestricted activity would be optimal, though this goal has yet to be achieved. Instrumentation has been developed to directly measure the strains and forces in human ligaments and tendons in vivo. The current strain measurement techniques include devices that attach directly to the tissue (e.g. Differential Variable Reluctance Transducer). The current force measurement techniques include the Buckle transducer, fiber optic sensors, and other implantable force probes that are placed in or around the mid-substance of the tissue. Noninvasive methods (e.g. ultrasonography, magnetic resonance imaging) have recently emerged to measure soft tissue strains and they show considerable promise. In this paper, the different techniques are reviewed with an emphasis on their advantages, limitations, and hence clinical relevance. These must be clearly understood in order to interpret the data reported in the literature that were obtained from such technologies, to design experiments that utilize these technologies, or to improve upon these technologies.

Animals↗
PubMed2004

Strain on the anterior cruciate ligament during closed kinetic chain exercises.

PURPOSE: The purpose of this investigation was to characterize the ACL strains produced during four commonly prescribed CKC exercises; the step-up, the step-down, the lunge, and the one-legged sit to stand. We hypothesized that the ACL strains produced during the lunge and one-legged sit to stand exercises (the exercises that challenge the leg musculature to a greater extent and utilize greater hip flexion) would be less than those produced during the step-up and step-down exercises. METHODS: The strains in the anteromedial bundle of the ACL were measured while nine subjects, who had normal ligaments, performed the four exercises. Peak ACL strain values and the ACL strain patterns as a function of knee flexion angle were compared between exercises. RESULTS: No significant differences were found between the peak ACL strain values (mean +/- SEM) between exercises (step-up: 2.5 +/- 0.36; step-down: 2.6 +/- 0.34; lunge 1.9 +/- 0.50; one-legged sit to stand: 2.8 +/- 0.27). The mean ACL strain values as a function of knee flexion angle were not significantly different. On average, there was a significant increase in ACL strain as the knee was extended for each exercise. CONCLUSIONS: The ACL strain responses produced during these CKC exercises were equal and similar to those produced during other rehabilitation exercises (i.e., squatting, active extension of the knee) previously tested.

Adult↗
PubMed2003

Anatomic rotational relationships of the proximal tibia, distal femur, and patella: implications for rotational alignment in total knee arthroplasty.

The orientation of the femur, tibia, and patella are important considerations in total knee arthroplasty. Our goal was to describe the relationships between the femoral epicondylar (FE) axis, posterior femoral (PF) axis, posterior tibial (PT) axis, patellar (PAT) axis, and patellar ligament (PL). A secondary goal was to determine where the short axis of the tibial tray intersects the patellar ligament as a function of tibial component rotation. Thirty normal magnetic resonance imaging (MRI) scans were analyzed. Strong relationships were found between the FE and PAT axes (2 degrees +/- 3 degrees, r(2) = 0.73), and between the FE and PF axes (6 degrees +/- 2 degrees, r(2) = 0.77). When the tibial baseplate was aligned along the PT axis, 30% of the cases were in an ideal position. When the FE axis was used, 73% were ideal.

Adult↗
PubMed2003

Tibial axis and patellar position relative to the femoral epicondylar axis during squatting.

A laboratory-based study was performed to describe the tibial axis and patellar position relative to the femoral epicondylar (FE) axis during squatting. During the squat, the angle between the tibial and FE axes averaged 90.5 degrees, and 66% of internal rotation of the tibia occurred before 15 degrees flexion. In the mid-sagittal plane of the femur, the patella followed a circular arc, and mediolateral patellar shift averaged 4.3 mm. These findings can be used as the basis for development of new total knee arthroplasty components that recreate normal patellofemoral kinematics, and may provide important guidelines for alignment of the tibial and femoral components. The perpendicular relationship between the tibial and the FE axes may be useful in locating the FE axis intraoperatively. The reduced mediolateral shift of the patella suggests that alignment of the femoral component with the FE axis will aid patellar tracking about a circular arc with small deviations in the medial-lateral direction.

Biomechanical Phenomena↗
PubMed2002

Chronic anterior cruciate ligament deficiency is associated with increased anterior translation of the tibia during the transition from non-weightbearing to weightbearing.

Translation of the tibia relative to the femur was measured while a group of subjects with normal knees and group with anterior cruciate ligament (ACL) tears underwent transition from non-weightbearing to weightbearing stance. Subjects were positioned in the Vermont knee laxity device (VKLD) with muscles relaxed and the limb segment and compressive joint load offset (non-weightbearing). A lateral radiograph of the knee, with the posterior aspects of the femoral condyles superimposed, was obtained to document the position of the tibia relative to the femur. Immediately after, a compressive load equal to 40% of bodyweight was applied to each foot, and a second radiograph was obtained to document the change in position of the tibia relative to the femur. The transition from non-weightbearing to weightbearing produced a significant increase of anterior translation of the tibia relative to the femur (mean; 3.4 mm) for the subjects with ACL tears compared with the contralateral normal knees (0.8 mm). Similarly, there was a significant increase in anterior translation of the tibia for the subjects with ACL tears compared to the group of subjects with normal knees (1.2 mm). The fourfold increase in anterior translation of the tibia for the knees with ACL tears compared to the contralateral side is a concern because it is substantially greater than the 95% confidence limits of the side-to-side differences in anterior-posterior knee laxity measured from subjects with normal knees. This observation could explain, at least in part, one of the mechanisms that initiates damage to the meniscus and articular cartilage in subjects that have suffered an ACL tear.

Adult↗
PubMed2002

Measurement of anterior-posterior knee laxity: a comparison of three techniques.

Several non-invasive techniques have been developed to assess anterior-posterior (A-P) laxity of the knee, however, their accuracy remains unclear. Roentgen Stereophotogrammetry Analysis (RSA) is a three-dimensional motion analysis method that has been shown to be an accurate tool for evaluating joint kinematics. Thus. RSA provides a means that can be used to evaluate other less invasive techniques. The objectives of this study were to compare A-P laxity values as measured using the KT-1000 Knee Arthrometer, planar stress radiography and RSA, and to determine if they detect similar changes in A-P laxity over time in 15 subjects following anterior cruciate ligament reconstruction with patellar tendon autografts. The A-P laxity values of the injured knee were measured immediately following surgery and at their 3-, 6-, and 12-month follow-up visits. A-P laxity was defined as the A-P translation of the tibia relative to the femur that occurred between the posterior and anterior shear load limits of -90 to +130 N, respectively. The values of A-P laxity across all time points were 11.4 +/- 3.0, 10.2 +/- 3.3, and 6.9 +/- 3.0 mm (mean +/- standard deviation) for the KT-1000, planar stress radiography and the RSA methods, respectively. These values were significantly different from each other (p < 0.001). The two-dimensional analyses techniques (planar stress radiography and the KT-1000) consistently over-estimated the true laxity values that were obtained using the three-dimensional RSA technique. Significant increases in A-P laxity values over time were also detected with the KT-1000 (p = 0.04) and the RSA technique (p = 0.04). However, this increase was not evident when using planar stress radiography (p = 0.89). This study determined that the KT-1000 and RSA document temporal changes in A-P laxity following ACL reconstruction that were not documented by planar stress radiography.

Adult↗
PubMed2002

The science of anterior cruciate ligament rehabilitation.

This review of the literature assessed what is known about the biomechanics of the normal anterior cruciate ligament during rehabilitation exercises, the biomechanical behavior of the anterior cruciate ligament graft during healing, and clinical studies of rehabilitation after anterior cruciate ligament replacement. After anterior cruciate replacement, immobilization of the knee, or restricted motion without muscle contraction, leads to undesired outcomes for the ligamentous, articular, and muscular structures that surround the joint. It is clear that rehabilitation that incorporates early joint motion is beneficial for reducing pain, minimizing capsular contractions, decreasing scar formation that can limit joint motion, and is beneficial for articular cartilage. There is evidence derived from randomized controlled trials that immediately after anterior cruciate ligament reconstruction, weightbearing is possible without producing an increase of anterior knee laxity and is beneficial because it lowers the incidence of patellofemoral pain. Rehabilitation with a closed kinetic chain program results in anteroposterior knee laxity values that are closer to normal, and earlier return to normal daily activities, compared with rehabilitation with an open kinetic chain program. This review revealed that more randomized, controlled trials of rehabilitation are needed. These should include the clinicians' and patients' perspective of the outcome, and biomarkers of articular cartilage metabolism.

Anterior Cruciate Ligament↗
PubMed2002

Effects of early and late stage cement intrusion into cancellous bone.

Minimizing aseptic loosening of cemented femoral stems in total hip arthroplasty remains a goal. Recent investigation suggests that improved cement intrusion may result from elevated pressures shown to occur during stem placement into higher viscosity late stage polymethylmethacrylate cement when compared with low viscosity early stage cement. The hypothesis tested is that placement of a femoral stem in late stage cement can increase cement-bone contact as compared with placement in early stage cement. The variable tested in this experiment was cement viscosity. Radiographic analysis was done on nine paired femurs from cadavers that had placement of a cemented femoral stem with either early or late stage polymethylmethacrylate. Radiographs were assessed quantitatively by measuring the extent of radiolucency observed at the cement-bone interface. Specimens that had late stage cement had significantly less radiolucency in the middle zone region, corresponding to combined Gruen Zones 2 and 6. Similar trends were observed in the proximal and distal zone regions of the stem. Elevated stem insertion pressure associated with late stage cement can minimize void space between the cement and trabecular bone. These findings suggest that the surgeon should consider femoral stem placement later in the cement cure cycle, generating higher intramedullary pressure, and leading to improved cement intrusion into the surrounding bone.

Aged↗
PubMed2002

Anterior cruciate ligament replacement: comparison of bone-patellar tendon-bone grafts with two-strand hamstring grafts. A prospective, randomized study.

BACKGROUND: The purpose of this investigation was to evaluate replacement of a torn anterior cruciate ligament with either a bone-patellar tendon-bone autograft or a two-strand semitendinosus-gracilis autograft to compare the results of clinical testing, patient satisfaction, activity level, functional status, and muscle strength. METHODS: Fifty-six patients with a torn anterior cruciate ligament were enrolled in a prospective, randomized, controlled study. Twenty-eight underwent reconstruction with a bone-patellar tendon-bone autograft, and twenty-eight were treated with a two-strand semitendinosus-gracilis autograft. Patients were followed for an average of thirty-nine months (range, thirty-six to fifty-seven months). At the time of final follow-up, twenty-two patients in each group were evaluated in terms of clinical test findings, patient satisfaction, activity level, functional status, and isokinetic muscle strength. RESULTS: The objective outcome of replacement of the torn anterior cruciate ligament with a bone-patellar tendon-bone graft was superior to that obtained with a two-strand semitendinosus-gracilis graft. At the three-year follow-up interval, the patients in whom a hamstring graft had been used had an average of 4.4 mm of increased anterior knee laxity compared with the laxity of the contralateral, normal knee, whereas the patients in whom a bone-patellar tendon-bone graft had been used had an average of 1.1 mm of increased knee laxity. Fourteen percent (three) of the twenty-two patients with a hamstring graft had a mild pivot shift, and 27% (six) had a moderate pivot shift. Only 14% (three) of the twenty-two patients with a bone-patellar tendon-bone graft had a mild pivot shift, and none had a moderate pivot shift. At the same follow-up interval, the patients in whom a hamstring graft had been used had significantly lower peak knee-flexion strength than those who had a bone-patellar tendon-bone graft (p = 0.039). In contrast, the two treatments produced similar outcomes in terms of patient satisfaction, activity level, and knee function (ability to perform a one-legged hop, bear weight, squat, climb stairs, run in place, and duckwalk). CONCLUSIONS: After three years of follow-up, the objective results of anterior cruciate ligament replacement with a bone-patellar tendon-bone autograft were superior to those of replacement with a two-strand semitendinosus-gracilis graft with regard to knee laxity, pivot-shift grade, and strength of the knee flexor muscles. However, the two groups had comparable results in terms of patient satisfaction, activity level, and knee function.

Adolescent↗
PubMed2002

The effect of bracing on proprioception of knees with anterior cruciate ligament injury.

This paper is a comprehensive review on the effect of bandaging, bracing, and neoprene sleeves on knee proprioception following anterior cruciate ligament (ACL) injury and reconstruction with a focus on studies that have measured joint position sense and threshold to detection of passive knee motion. Disruption of the ACL does not appear to alter joint position sense soon after injury, although there is evidence that in some subjects deterioration may occur over time. An ACL tear creates a deficit in the threshold to detection of passive knee motion soon after injury and in those with chronic tears. The magnitude of worsening is less then 1.0 degree of movement in flexion-extension and of questionable concern from a clinical and functional perspective. Application of a functional brace or neoprene sleeve to the ACL-deficient limb does not improve the threshold to detection of passive knee motion; however, application of an elastic bandage to a knee with an ACL tear improves joint position sense. Reconstruction of a torn ACL is associated with a deficit in the threshold to detection of passive knee motion, and during the first year of healing the use of a neoprene sleeve provides improvement. Two years following ACL reconstruction there is no deficit in the threshold to detection of passive knee motion and the use of a brace has no effect on this outcome.

Anterior Cruciate Ligament↗
PubMed2002

Predictive Factors for Lateral Ankle Sprains: A Literature Review.

OBJECTIVE: To review the prospective studies of ankle-ligament-injury risk factors. DATA SOURCES: We searched MEDLINE from 1978 to 2001 using the terms ankle, ligament, injury, risk factor, and epidemiology. DATA SYNTHESIS: The results included many studies on the treatment and prevention of ankle injuries. There were, however, very few prospective studies focusing on identifying the risk factors that predispose an athlete to ankle-ligament trauma. CONCLUSIONS/RECOMMENDATIONS: There is some agreement among authors with regard to the risk factors for ankle-ligament injury; however, considerable controversy remains. Although female athletes are at significantly greater risk of suffering a serious knee sprain, such as disruption of the anterior cruciate ligament, this does not appear to be the case for ankle-ligament sprains. Therefore, sex does not appear to be a risk factor for suffering an ankle-ligament sprain. Athletes who have suffered a previous sprain have a decreased risk of reinjury if a brace is worn, and the consensus is that generalized joint laxity and anatomical foot type are not risk factors for ankle sprains. However, the literature is divided with regard to whether or not height, weight, limb dominance, ankle-joint laxity, anatomical alignment, muscle strength, muscle-reaction time, and postural sway are risk factors for ankle sprains. Future research is needed on this topic to develop a consensus on all ankle-injury risk factors. This will allow future intervention studies to be designed that will reduce the incidence and severity of this common injury.

Journal Article↗
PubMedDate not supplied

The effect of anterior cruciate ligament deficiency and functional bracing on translation of the tibia relative to the femur during nonweightbearing and weightbearing.

BACKGROUND: Much of what is known about functional bracing is derived from studies of the knee during unweighted or weightbearing conditions, whereas little is known about the transition between these postures. HYPOTHESIS: Bracing the anterior cruciate ligament-deficient knee during nonweightbearing, throughout the transition to weightbearing, and during weightbearing reduces the abnormal translations of the tibia relative to the femur to within the limits of normal. STUDY DESIGN: Controlled laboratory study. METHODS: Subjects with chronic anterior cruciate ligament tears were studied with and without braces. Anteroposterior shear and compressive loads were applied to the knee, and translations of the tibia relative to the femur were measured while subjects were nonweightbearing, throughout the transition to weightbearing, and during weightbearing. RESULTS: Bracing the anterior cruciate ligament-deficient knee resulted in a significant reduction of anteroposterior laxity values, to a level within the limits of the normal knee during nonweightbearing and weightbearing postures. In contrast, when the anterior cruciate ligament-deficient knees transitioned from nonweightbearing to weightbearing, the anterior translation of the tibia relative to the femur was 3.5 times greater than in the normal knee, and bracing did not reduce this to within the limits of normal. CONCLUSIONS: Bracing a knee with a chronic anterior cruciate ligament tear was effective in reducing abnormal anteroposterior laxity during nonweightbearing and weightbearing; however, braces were not effective in reducing the abnormal anterior translations produced by the change between these postures. CLINICAL RELEVANCE: This study explains why subjects with anterior cruciate ligament tears gain partial control of pathologic anteroposterior laxity with the use of a brace but may continue to experience abnormal translations during activity.

Adult↗
PubMedDate not supplied

Anterior drawer test for acute anterior talofibular ligament injuries of the ankle. How much load should be applied during the test?

BACKGROUND: There is a lack of consensus regarding the magnitude of load for performing the anterior drawer test in evaluating acute ankle injuries. PURPOSE: To determine how much load should be applied during the anterior drawer test to detect the integrity of the anterior talofibular ligament. METHODS: First, the anterior-posterior load-displacement response of nine cadaveric ankles was measured. Second, anterior displacement of the ankle was measured at 30 and 60 N of anterior load in 14 patients with acute tears of the anterior talofibular ligament. RESULTS: In the cadaver study, the increased displacement by sectioning of the ligament measured at 10, 20, 30, and 40 N of anterior load were significantly greater than those measured at 60 N. In vivo examination of the subjects without anesthesia demonstrated that the injured-to-normal displacement value at 30 N of anterior load was significantly greater than the value at 60 N. CONCLUSIONS: This study suggests that a large magnitude of anterior load is not necessary to detect the integrity of the ligament during the anterior drawer test. CLINICAL RELEVANCE: When evaluating the integrity of the anterior talofibular ligament in cases of acute ankle ligament injury, a relatively low-magnitude load should be applied.

Acute Disease↗