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Biomedical subjects

Bruce D Beynnon

Publications and source records attributed to Bruce D Beynnon.

At least 19 recordsLinked to original sources
PubMed2007

Early revision for component malrotation in total knee arthroplasty.

Component malrotation may result in unsuccessful total knee arthroplasty. We asked whether revision improves function in patients with malrotated total knee arthroplasty components. We retrospectively reviewed 22 revision total knee arthroplasties performed for femoral and/or tibial component malrotation. Revision surgery was performed within 2 years of the primary arthroplasty in 81% of the cases (18 of 22) with the remainder within 5 years. Although all patients had pain, 32% of patients had associated instability and 36% of patients had poor range of motion. Average Knee Society Scores improved from 42 preoperatively to 77 postoperatively. Average Oxford Knee Scores improved from 38 preoperatively to 29 postoperatively. Although clinical and functional improvement was observed, these results are inferior to those for primary knee arthroplasty, and they emphasize the need for proper component rotational positioning during primary total knee arthroplasty. Internal component malrotation leads not only to patellofemoral problems, but also to difficulty in gap balancing and femoral component sizing, which may in turn lead to either poor range of motion or symptoms of knee instability.

Adult↗
PubMed2006

A prospective, randomized clinical investigation of the treatment of first-time ankle sprains.

BACKGROUND: Acute ankle ligament sprains are treated with the use of controlled mobilization with protection provided by external support (eg, functional treatment); however, there is little information regarding the best type of external support to use. HYPOTHESIS: There is no difference between elastic wrapping, bracing, bracing combined with elastic wrapping, and casting for treatment of acute, first-time ankle ligament sprains in terms of the time a patient requires to return to normal function. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Patients suffering their first ligament injury were stratified by the severity of the sprain (grades I, II, or III) and then randomized to undergo functional treatment with different types of external supports. The patients completed daily logs until they returned to normal function and were followed up at 6 months. RESULTS: Treatment of grade I sprains with the Air-Stirrup brace combined with an elastic wrap returned subjects to normal walking and stair climbing in half the time required for those treated with the Air-Stirrup brace alone and in half the time required for those treated with an elastic wrap alone. Treatment of grade II sprains with the Air-Stirrup brace combined with the elastic wrap allowed patients to return to normal walking and stair climbing in the shortest time interval. Treatment of grade III sprains with the Air-Stirrup brace or a walking cast for 10 days followed by bracing returned subjects to normal walking and stair climbing in the same time intervals. The 6-month follow-up of each sprain severity group revealed no difference between the treatments for frequency of reinjury, ankle motion, and function. CONCLUSION: Treatment of first-time grade I and II ankle ligament sprains with the Air-Stirrup brace combined with an elastic wrap provides earlier return to preinjury function compared to use of the Air-Stirrup brace alone, an elastic wrap alone, or a walking cast for 10 days.

Adolescent↗
PubMed2006

The effect of coordinate system choice and segment reference on RSA-based knee translation measures.

Roentgen stereophotogrammetric analysis (RSA) can be utilized to accurately describe joint kinematics, but even when measuring small displacements within radiographically discernible structures, standardized reference frames are imperative for useful comparison across patients and across studies. In the current paper, accurately controlled laboratory models demonstrated the considerable influence that a mere 1.9-cm offset of the origin of the coordinate system from the rotation axes could exert on translation measures when rotations were occurring. In addition, the use of two different coordinate systems to gauge translation on a radiographic anterior-posterior (A-P) knee laxity exam resulted in a significant correlation (R(2)=0.562) between the two systems; however, differences of up 9.28 mm were found between corresponding measurements. This implies that clinical conclusions can potentially be upheld or refuted, based on the same data set, subject to coordinate system definition. Although the data analyzed presently involved the knee joint, similar issues surround the RSA motion analysis of other joints as well.

Algorithms↗
PubMed2006

The relationship between menstrual cycle phase and anterior cruciate ligament injury: a case-control study of recreational alpine skiers.

BACKGROUND: Female athletes suffer a greater incidence of anterior cruciate ligament tears compared with male athletes when participating in common sports; however, very little is known about the factors that explain this disparity. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Female recreational alpine skiers with an anterior cruciate ligament rupture and age-matched control skiers provided a serum sample and self-reported menstrual history data immediately after injury. Both serum concentrations of progesterone and menstrual history were then used to group subjects into either preovulatory or postovulatory phases of the menstrual cycle. RESULTS: Analysis of serum concentrations of progesterone revealed that alpine skiers in the preovulatory phase of the menstrual cycle were significantly more likely to tear their anterior cruciate ligaments than were skiers in the postovulatory phase (odds ratio, 3.22; 95% confidence interval, 1.09-9.52; P = .027). Analysis of menstrual history data found similar results, but the difference was not statistically significant (odds ratio, 2.38; 95% confidence interval, 0.86-6.54; P = .086). CONCLUSION: The likelihood of sustaining an anterior cruciate ligament injury does not remain constant during the menstrual cycle; instead, the risk of suffering an anterior cruciate ligament disruption is significantly greater during the preovulatory phase of the menstrual cycle compared with the postovulatory phase. CLINICAL RELEVANCE: Phase of menstrual cycle may be one of the risk factors that influence knee ligament injury among female alpine skiers. The findings from this study should be considered in subsequent studies designed to identify persons at risk for anterior cruciate ligament injury and to develop intervention strategies.

Adolescent↗
PubMed2006

Nonweight-bearing anterior knee laxity is related to anterior tibial translation during transition from nonweight bearing to weight bearing.

We examined the relationship between anterior knee laxity (AKL), evaluated while the knee was nonweight bearing, and anterior translation of the tibia relative to the femur (ATT), evaluated when the knee transitioned from nonweight-bearing to weight-bearing conditions in response to an applied compressive load at the foot. Twenty subjects with normal knees (10 M, 10 F; 25.2 +/- 4.1 years, 169.8 +/- 11.5 cm, 71.6 +/- 16.9 kg) underwent measurements of AKL and ATT of the right knee on 2 days. AKL was measured at 133N with the KT-2000. ATT was measured with the Vermont Knee Laxity Device and electromagnetic position sensors attached to the patella and the anteromedial aspect of the proximal tibia. Three trials for each measure were averaged and analyzed. Measurement consistency was high for both AKL (ICC = 0.97; SEM = 0.44 mm) and ATT (ICC = 0.88; SEM = 0.84 mm). Linear regression revealed that AKL predicted 35.5% of the variance in ATT (p = 0.006), with a prediction equation of Y(ATT) = 3.20 + 0.543(X(AKL)). Our findings suggest that increased AKL is associated with increased ATT as the knee transitions from nonweight-bearing to weight-bearing conditions. The potential for increased knee joint laxity to disrupt normal knee biomechanics during activities such as landing from a jump, or the foot strike phase of gait deserves further study.

Adult↗
PubMed2006

Intratester and intertester reliability of clinical measures of lower extremity anatomic characteristics: implications for multicenter studies.

OBJECTIVE: To determine whether multiple examiners could be trained to measure lower extremity anatomic characteristics with acceptable reliability and precision, both within (intratester) and between (intertester) testers. We also determined whether testers trained 18 months apart could perform these measurements with good agreement. SETTING: University's Applied Neuromechanics Research Laboratory. PARTICIPANTS: Sixteen, healthy participants (7 men, 9 women). ASSESSMENT OF RISK FACTORS: Six investigators measured 12 anatomic characteristics on the right lower extremity in the Fall of 2004. Four testers underwent training immediately preceding the study, and measured subjects on 2 separate days to examine intratester reliability. Two testers trained 18 months before the study (Spring 2002) measured each subject on day 1 to examine the consistency of intertester reliability when testers are trained at different times. MAIN OUTCOME MEASUREMENTS: Knee laxity, genu recurvatum, quadriceps angle, tibial torsion, tibiofemoral angle, hamstring extensibility, pelvic angle, navicular drop, femur length, tibial length, and hip anteversion. RESULTS: With few exceptions, all testers consistently measured each variable between test days (intraclass correlation coefficient>or=0.80). Intraclass correlation coefficient values were lower for intertester reliability (0.48 to 0.97), and improved from day 1 to day 2. Intertester reliability was similar when comparing testers trained 18 months before those trained immediately before the study. Absolute measurement error varied considerably across individual testers. CONCLUSIONS: Multiple investigators can be trained at different times to measure anatomic characteristics with good to excellent intratester reliability. Intratester reliability did not always ensure acceptable intertester reliability or measurement precision, suggesting more training (or more experience) may be required to achieve acceptable measurement reliability and precision between multiple testers.

Adult↗
PubMed2006

Understanding and preventing noncontact anterior cruciate ligament injuries: a review of the Hunt Valley II meeting, January 2005.

The incidence of noncontact anterior cruciate ligament injuries in young to middle-aged athletes remains high. Despite early diagnosis and appropriate operative and nonoperative treatments, posttraumatic degenerative arthritis may develop. In a meeting in Atlanta, Georgia (January 2005), sponsored by the American Orthopaedic Society for Sports Medicine, a group of physicians, physical therapists, athletic trainers, biomechanists, epidemiologists, and other scientists interested in this area of research met to review current knowledge on risk factors associated with noncontact anterior cruciate ligament injuries, anterior cruciate ligament injury biomechanics, and existing anterior cruciate ligament prevention programs. This article reports on the presentations, discussions, and recommendations of this group.

Anterior Cruciate Ligament↗
PubMed2005

Material properties of articular cartilage in the rabbit tibial plateau.

The material properties of articular cartilage in the rabbit tibial plateau were determined using biphasic indentation creep tests. Cartilage specimens from matched-pair hind limbs of rabbits approximately 4 months of age and greater than 12 months of age were tested on two locations within each compartment using a custom built materials testing apparatus. A three-way ANOVA was used to determine the effect of leg, compartment, and test location on the material properties (aggregate modulus, permeability, and Poisson's ratio) and thickness of the cartilage for each set of specimens. While no differences were observed in cartilage properties between the left and right legs, differences between compartments were found in each set of specimens. For cartilage from the adolescent group, values for aggregate modulus were 40% less in the medial compartment compared to the lateral compartment, while values for permeability and thickness were greater in the medial compartment compared to the lateral compartment (57% and 30%, respectively). Values for Poisson's ratio were 19% less in the medial compartment compared to the lateral compartment. There was also a strong trend for thickness to differ between test locations. Similar findings were observed for cartilage from the mature group with values for permeability and thickness being greater in the medial compartment compared to the lateral compartment (66% and 34%, respectively). Values for Poisson's ratio were 22% less in the medial compartment compared to the lateral compartment.

Animals↗
PubMed2005

First-time inversion ankle ligament trauma: the effects of sex, level of competition, and sport on the incidence of injury.

BACKGROUND: Inversion ankle trauma is disabling, yet little is known regarding the incidence rate of first-time ankle sprains and how it is influenced by factors including sex, level of competition, and sport. HYPOTHESIS: The incidence rates of first-time ankle ligament sprains are influenced by sex, level of competition (high school vs college), and type of sports participation (basketball, soccer, lacrosse, and field hockey). STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Between 1999 and 2003, high school and college athletes were evaluated before participation in their sports. Subjects were included in the study if they had not experienced a prior ankle or lower extremity injury and were then followed during participation in soccer, basketball, lacrosse, or field hockey to document their days of exposure to sport and injuries sustained. The relative risk associated with sex, level of competition, and sport was estimated by Cox regression. RESULTS: A total of 901 athletes had 50 680 person-days of exposure to sports, and 43 (4.8%) had an inversion injury that produced an ankle ligament sprain. Overall, the injury incidence rate was 0.85 sprains per 1000 person-days of exposure to sport. There were 0.68 and 0.97 ankle sprains per 1000 person-days of exposure to sport for the men and women, respectively. Although the risk of suffering an ankle sprain was higher for women than for men (relative risk, 1.51), the difference was not statistically significant (P = .21) and was owing to the increased risk in female basketball athletes compared to male basketball athletes (relative risk, 4.11; P = .045). Risk of injury was similar for the high school athletes in comparison to the college athletes (relative risk, 1.16). For the men, there was no difference in the risk of suffering an ankle sprain between the sports of basketball, soccer, and lacrosse, whereas for the women, the risk of suffering an ankle sprain was significantly greater during participation in basketball compared to lacrosse. CONCLUSION: In this study of first-time ankle sprains, for most sports, the incidence rate of inversion injury is less than 1 per 1000 days of exposure to sport, a value lower than previously reported. Among female athletes, ankle injury is associated with type of sport. Risk is highest for female basketball athletes, who are at significantly greater risk than male basketball athletes and female lacrosse athletes. The risk of first-time ankle injury is similar for high school and college-level athletes.

Adolescent↗
PubMed2005

The effect of estradiol and progesterone on knee and ankle joint laxity.

BACKGROUND: Female athletes suffer a higher incidence of anterior cruciate ligament injuries compared to their male counterparts, and they appear to be at increased risk for these injuries when they have increased anterior-posterior knee laxity and at specific phases of the menstrual cycle. Although the mechanism by which these factors combine to increase injury risk is unclear, studies suggest that cyclic variations in joint laxity produced by hormone fluctuation during the menstrual cycle predispose an athlete to increased risk of ligamentous injury. Little is known about whether joint laxity varies cyclically during the menstrual cycle and if so, whether it is modulated by cyclic variations of estradiol (E2) and progesterone (P4). HYPOTHESIS: Increased serum estradiol (E2) and progesterone (P4) levels are associated with increased ankle and knee joint laxity. STUDY DESIGN: Cohort study. Level of evidence, 2. METHODS: Ankle laxity, anterior-posterior knee laxity, and serum concentrations of estradiol (E2) and progesterone (P4) were measured during the menstrual cycle in women and at corresponding time intervals in men (controls). Ankle laxity was measured from stress radiographs and included anterior talar translation relative to the tibia and talar tilt relative to the tibia; anterior-posterior knee laxity was measured with the KT-1000 arthrometer. RESULTS: Women had greater knee and ankle laxity values compared to men. There was, however, no change in knee and ankle laxity over the normal menstrual cycle in women and no change over time in men. There was no relationship between estradiol and progesterone fluctuation and ankle and knee joint laxity. CONCLUSIONS: Knee and ankle joint laxities are greater for women compared to men; however, the cyclic estradiol and progesterone fluctuations that occur during the menstrual cycle do not produce cyclic fluctuations of joint laxity. Studies using joint laxity to identify a subject at risk for ligamentous injury need only consider making measurements at a specific point in time, such as during a preseason screening evaluation.

Adult↗
PubMed2005

Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading.

The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0 degrees and 20 degrees of plantar flexion) for a total of 16 tests per specimen. Three commercially available braces (two semirigid types and one lace up type) were evaluated. An axial compression load significantly decreased ankle-subtalar motion in unbraced ankles for the tested inversion moment. The contribution of bracing to stabilization of the ankle was smaller in the axial loading condition than in the no axial loading condition. The semirigid braces had greater stabilizing effects in response to the inversion moment than the lace up brace. Stabilizing effects of bracing were significantly greater in 20 degrees of plantar flexion than in 0 degrees of plantar flexion. The most common mechanism for an ankle sprain injury is inversion rotation on a weight-bearing ankle. Therefore, we should not overestimate stabilizing effects of bracing from evaluations of bracing without axial compression loading.

Adult↗
PubMed2005

Radiographic measurement of anterior talar translation in the ankle: determination of the most reliable method.

BACKGROUND: Although most would agree that stress radiography is an important research tool to evaluate the integrity of the ankle ligaments in studies of chronic ankle instability, there is little agreement with regard to the best technique to make these measurements. The primary objective of this study was to establish the most reliable method for measuring anterior displacement of the talus relative to the tibia using stress radiographs of the ankle. This information is necessary to standardize radiographic evaluation of injured ankles and for biomechanical studies of the ankle joint, but has never been investigated. METHODS: This study examined the reliability of four available methods by measuring the intra-observer repeatability and inter-observer reproducibility of three different investigators. Lateral radiographs were obtained while the ankle was supported in the Telos device with the joint unloaded, and then with a 150 N anterior directed load applied to the calcaneus. At two separate time intervals, the radiographs were read by three different observers using four measurement techniques. For each technique, the measurement of the unloaded ankle was subtracted from the loaded ankle to obtain anterior talar translation. FINDINGS: The method that measured the shortest distance between the posterior lip of the distal tibia and the talar dome (designated Method I in the current series) was significantly more reproducible between readers and within readers across repeated measurements than the other methods tested. INTERPRETATION: Based on the findings from this study, it can be concluded that measurement of the distance between the posterior lip of the distal tibia and the talar dome is the method of choice to characterize the position of the talus relative to the tibia in stress radiography. In order to standardize the radiographic evaluation of ankle injuries, this method should be the one employed to measure anterior talar translation.

Ankle Injuries↗
PubMed2005

In vivo loads in the medial compartment of the rabbit knee.

BACKGROUND: The compressive loads produced in the medial compartment of a rabbit knee during hopping are unknown, and necessary for the development of an animal model to study unicompartmental osteoarthritis. METHODS: In an effort to obtain such data, a surgical procedure was developed to insert a pressure sensor into the medial tibial compartment of a New Zealand white rabbit knee joint, and an inactive sensor of the same thickness into the lateral tibial compartment. After the rabbits recovered from anesthesia, contact pressure was measured as the rabbits hopped. FINDINGS: The average peak pressure in the medial compartment was 60 N/cm2 (SD 16), a value that corresponds to 39% of the animals' body weight (range: 21-61%, SD 11%). INTERPRETATION: This is the first report of measured in vivo pressures associated with the load transmitted through the medial compartment of the skeletally mature New Zealand White rabbit, a model frequently used to study the progression of osteoarthritis.

Animals↗
PubMed2005

Open- or closed-kinetic chain exercises after anterior cruciate ligament reconstruction?

Open-kinetic chain (OKC) and closed-kinetic chain (CKC) exercises may not differ in their effects on the healing response of the anterior cruciate ligament (ACL)-reconstructed knee. Recent biomechanical studies have shown that the peak strains produced on a graft are similar. Clinical studies suggest that both play a beneficial role in the early rehabilitation of the reconstructed knee.

Anterior Cruciate Ligament↗
PubMed2005

Rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind comparison of programs administered over 2 different time intervals.

BACKGROUND: There are adverse effects associated with immobilization of the knee after anterior cruciate ligament reconstruction, yet very little is known about how much activity will promote adequate rehabilitation without permanently elongating the graft, producing graft failure, or creating damage to articular cartilage. HYPOTHESIS: Rehabilitation with either an accelerated or nonaccelerated program produces no difference in anterior-posterior knee laxity, clinical assessment, patient satisfaction, functional performance, and the synovial fluid biomarkers of articular cartilage metabolism. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Twenty-five patients who tore their anterior cruciate ligament were enrolled and underwent anterior cruciate ligament reconstruction. Patients were randomized to accelerated rehabilitation or nonaccelerated rehabilitation. At the time of surgery and 3, 6, 12, and 24 months later, measurements of anterior-posterior knee laxity, clinical assessment, patient satisfaction, functional performance, and cartilage metabolism were completed. RESULTS: At the 2-year follow-up, there was no difference in the increase of anterior knee laxity relative to the baseline values that were obtained immediately after surgery between the 2 groups (2.2-mm vs 1.8-mm increase relative to the normal knee). The groups were similar in terms of clinical assessment, patient satisfaction, activity level, function, and response of the bio-markers. After 1 year of healing, synthesis of collagen and turnover of aggrecan remained elevated in both groups. CONCLUSION: Anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft followed by either accelerated or nonaccelerated rehabilitation produces the same increase of anterior knee laxity. Both programs had the same effect in terms of clinical assessment, patient satisfaction, functional performance, and the biomarkers of articular cartilage metabolism. There is concern that the cartilage biomarkers remained elevated for an extended period.

Adolescent↗
PubMed2005

Treatment of anterior cruciate ligament injuries, part I.

Anterior cruciate ligament injuries are common among athletes. Although the true natural history remains unclear, anterior cruciate ligament injuries are functionally disabling; they predispose the knee to subsequent injuries and the early onset of osteoarthritis. This article, the first in a 2-part series, was initiated with the use of the PubMed database and a comprehensive search of articles that appeared between January 1994 to the present, using the keywords anterior cruciate ligament. A total of 3810 citations were identified and reviewed to determine the current state of knowledge about the treatment of these injuries. Articles pertaining to the biomechanical behavior of the anterior cruciate ligament, the prevalence of anterior cruciate ligament injury, the natural history of the anterior cruciate ligament-deficient knee, injuries associated with anterior cruciate ligament disruption, risk factors for anterior cruciate ligament injury, indications for treatment of anterior cruciate ligament injuries, and nonoperative and operative treatments were obtained, reviewed, and served as the basis for part I. Part II, to be presented in another issue of this journal, includes technical aspects of anterior cruciate ligament surgery, bone tunnel widening, graft healing, rehabilitation after reconstruction, and the effect of sex, age, and activity level on the outcome of surgery. Our approach was to build on prior reviews and to provide an overview of the literature for each of the before-mentioned areas of study by summarizing the highest level of scientific evidence available. For the areas that required a descriptive approach to research, we focused on the prospective studies that were available; for the areas that required an experimental approach, we focused on the prospective, randomized controlled trials and, when necessary, the highest level of evidence available. We were surprised to learn that considerable advances have been made during the past decade regarding the treatment of this devastating injury.

Anterior Cruciate Ligament↗
PubMed2005

Treatment of anterior cruciate ligament injuries, part 2.

Anterior cruciate ligament tears, common among athletes, are functionally disabling; they predispose the knee to subsequent injuries and the early onset of osteoarthritis. A total of 3810 studies published between January 1994 and the present were identified and reviewed to determine the current state of knowledge regarding the treatment of anterior cruciate ligament injuries. Part 1 of this article focused on studies pertaining to the biomechanical behavior of the anterior cruciate ligament, the prevalence of and risk factors for injuries related to it, the natural history of the ligament-deficient knee, injuries associated with anterior cruciate ligament disruption, indications for the treatment of anterior cruciate ligament injuries, as well as nonoperative and operative treatments. Part 2 includes technical aspects of anterior cruciate ligament surgery, bone tunnel widening, graft healing, rehabilitation after anterior cruciate ligament reconstruction, and the effects of sex, age, and activity level on the outcome of such reconstructive surgery.

Age Factors↗