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Biomedical subjects

William E Garrett

Publications and source records attributed to William E Garrett.

At least 19 recordsLinked to original sources
PubMed2007

Forefoot loading during 3 athletic tasks.

BACKGROUND: Due to the popularity of soccer and the high incidence of injury among soccer players, it is valuable to know the effects of tasks like side cuts, crossover cuts, and forward acceleration on the foot. PURPOSE: To determine the differences in forefoot loading during three different athletic tasks. STUDY DESIGN: Descriptive laboratory study. METHODS: Thirty-six subjects (17 women and 19 men) were tested. Subjects ran a slalom-style agility course 5 times while plantar pressure data was collected at 100 Hz. Plantar pressure was recorded under both feet; however, a right-foot contact was used in the analysis of the side-cut task, a left-foot plant was used in the analysis of the crossover cut, and an average of the 3 steps of acceleration were used in the analysis. The peak pressure, contact area, and contact time for the entire foot were compared between the 3 tasks. The force and the force-time integral were obtained during 5 trials for each of the 3 tasks. The foot was divided into 8 masked regions, which were used to determine the loading patterns specifically in the forefoot. Each variable was analyzed using a 1 x 3 analysis of variance to determine differences between the three movement tasks in the forefoot region (a = .05). RESULTS: Significant differences in peak pressure, contact area, and contact time existed between the movement tasks when examining the entire foot. In addition, significant differences in the force-time integral and peak pressure in the forefoot existed between the movement tasks. The force-time integral was highest during the side cut in the medial forefoot, hallux, and the lesser toes, while the force-time integral was highest during the crossover cut in the middle forefoot and the lateral forefoot. Similarly, the peak pressure was highest during the side cut in the medial forefoot, hallux, and the lesser toes, while peak pressure was highest in the middle forefoot during the acceleration task and highest in the lateral forefoot during the crossover-cutting task. CONCLUSIONS: The results of this study demonstrated that the crossover cut places an increased load on the lateral portion of the forefoot, while the side-cut task places an increased load on the medial portion of the forefoot and the acceleration task places increased load on the middle forefoot. CLINICAL RELEVANCE: The differences in loading patterns based on athletic task are important for understanding potential injury mechanisms. In addition, this information could be important for defining a return to play protocol for athletes who have had specific injuries.

Adult↗
PubMed2006

Kinematics and electromyography of landing preparation in vertical stop-jump: risks for noncontact anterior cruciate ligament injury.

BACKGROUND: Biomechanical analysis of stop-jump tasks has demonstrated gender differences during landing and a potential increase in risk of noncontact anterior cruciate ligament injury for female athletes. Analysis of landing preparation could advance our understanding of neuromuscular control in movement patterns and be applied to the development of prevention strategies for noncontact anterior cruciate ligament injury. HYPOTHESIS: There are differences in the lower extremity joint angles and electromyography of male and female recreational athletes during the landing preparation of a stop-jump task. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional videographic and electromyographic data were collected for 36 recreational athletes (17 men and 19 women) performing vertical stop-jump tasks. Knee and hip angular motion patterns were determined during the flight phase before landing. RESULTS: Knee and hip motion patterns and quadriceps and hamstring activation patterns exhibited significant gender differences. Female subjects generally exhibited decreased knee flexion (P = .001), hip flexion (P = .001), hip abduction (P = .001), and hip external rotation (P = .03); increased knee internal rotation (P = .001); and increased quadriceps activation (P = .001) compared with male subjects. Female subjects also exhibited increased hamstring activation before landing but a trend of decreased hamstring activation after landing compared with male subjects (P = .001). CONCLUSION: Lower extremity motion patterns during landing of the stop-jump task are preprogrammed before landing. Female subjects prepared for landing with decreased hip and knee flexion at landing, increased quadriceps activation, and decreased hamstring activation, which may result in increased anterior cruciate ligament loading during the landing of the stop-jump task and the risk for noncontact ACL injury.

Adult↗
PubMed2006

Report of a group developing a virtual reality simulator for arthroscopic surgery of the knee joint.

Apprenticeship training of surgical skills is time consuming and can lead to surgical errors. Our group is developing an arthroscopic virtual reality knee simulator for training orthopaedic residents in arthroscopic surgery before live-patient operating room experience. The simulator displays realistic human knee anatomy derived from the Visible Human Dataset developed by the National Library of Medicine and incorporates active force-feedback haptic technology. Our premise is that postgraduate year 2 residents completing a formal virtual education program who are trained to reach a proficiency standard in the techniques and protocol for an arthroscopic knee examination will complete a diagnostic arthroscopy on an actual patient in less time with greater accuracy, less iteration of movement of the arthroscope, and less damage to the patient's tissue compared with residents in the control group learning and practicing the arthroscopic knee examination procedures through the residency program's established education and training program. The validation study, done at eight orthopaedic residency programs, will commence in early 2006 and will take one year to complete. We anticipate that proficiency obtained on the simulator will transfer to surgical skills in the operating room.

Arthroscopy↗
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↗
PubMed2006

Surgical management of anterior cruciate ligament injuries in patients with open physes.

Because of the increasing number of skeletally immature athletes who compete in highly demanding sports, more children than previously are sustaining anterior cruciate ligament injuries. Treatment and patient compliance with treatment recommendations are problematic. Pediatric issues include those specific to evaluation, projected growth, and surgery. Strict activity modification can protect the knee from further injury and delay surgery, sometimes until maturity. Surgical options include physeal-sparing, partial transphyseal, and complete transphyseal procedures. Surgical procedures are demanding because typical drilling and fixation techniques can affect the physis and possibly lead to growth disturbances. A wide range of growth disturbances has been reported; these must be understood to perfect surgical technique and avoid potential growth concerns. Surgical challenges, options regarding delayed surgery, and possible outcomes all need to be clearly communicated to the patient and parents.

Anterior Cruciate Ligament↗
PubMed2005

Lower extremity biomechanics during the landing of a stop-jump task.

BACKGROUND: Literature shows that landing with great impact forces may be a risk factor for knee injuries. The purpose of this study was to examine the relationships among selected lower extremity kinematics and kinetics during the landing of a stop-jump task. METHODS: Landmark coordinates and ground reaction forces during a stop-jump task were collected. Lower extremity joint angles and resultants were reduced. Pearson correlation coefficients among selected lower extremity kinematics and kinetics were determined. FINDINGS: The hip flexion angular velocity at the initial foot contact had significant correlation with peak posterior and vertical ground reaction forces (r = -0.63, P < 0.001, r = -0.48, P < 0.001) during the landing of the stop-jump task. The knee flexion angular velocity at the initial foot contact also had significant correlation with peak posterior and vertical ground reaction force (r = -0.49, P < 0.001, r = -0.06, P < 0.001) during the landing of the stop-jump task. Peak proximal tibia anterior shear force and peak knee extension moment during landing of the stop-jump task had significantly correlation with the corresponding posterior and vertical ground reaction forces (r > 0.51, P < 0.001). INTERPRETATION: A large hip and knee flexion angles at the initial foot contact with the ground do not necessarily reduce the impact forces during the landing of the stop-jump task, but active hip and knee flexion motions do. Hip joint motion at the initial foot contact with the ground appears to be an important technical factor that affects anterior cruciate ligament loading during the landing of the stop-jump task.

Adolescent↗
PubMed2005

Age and gender effects on lower extremity kinematics of youth soccer players in a stop-jump task.

BACKGROUND: Gender differences in lower extremity motion patterns were previously identified as a possible risk factor for non-contact anterior cruciate ligament injuries in sports. HYPOTHESIS: Gender differences in lower extremity kinematics in the stop-jump task are functions of age for youth soccer players between 11 and 16 years of age. STUDY DESIGN: Descriptive laboratory study. METHODS: Three-dimensional videographic data were collected for 30 male and 30 female adolescent soccer players between 11 and 16 years of age performing a stop-jump task. The age effects on hip and knee joint angular motions were compared between genders using multiple regression analyses with dummy variables. RESULTS: Gender and age have significant interaction effects on standing height (P = .00), body mass (P = .00), knee flexion angle at initial foot contact with the ground (P = .00), maximum knee flexion angle (P = .00), knee valgus-varus angle (P = .00), knee valgus-varus motion (P = .00), and hip flexion angle at initial foot contact with the ground (P = .00). CONCLUSION: Youth female recreational soccer players have decreased knee and hip flexion angles at initial ground contact and decreased knee and hip flexion motions during the landing of the stop-jump task compared to those of their male counterparts. These gender differences in knee and hip flexion motion patterns of youth recreational soccer players occur after 12 years of age and increase with age before 16 years. CLINICAL RELEVANCE: The results of this study provide significant information for research on the prevention of noncontact anterior cruciate ligament injuries.

Adolescent↗
PubMed2005

Instruction of jump-landing technique using videotape feedback: altering lower extremity motion patterns.

BACKGROUND: Anterior cruciate ligament injury prevention programs have used videotapes of jump-landing technique as a key instructional component to improve landing performance. HYPOTHESIS: All videotape feedback model groups will increase knee flexion angles at initial contact and overall knee flexion motion and decrease peak vertical ground reaction forces and peak proximal anterior tibial shear forces to a greater extent than will a nonfeedback group. The secondary hypothesis is that the videotape feedback using the combination of the expert and self models will create the greatest change in each variable. STUDY DESIGN: Controlled laboratory study. METHODS: Knee kinematics and kinetics of college-aged recreational athletes randomly placed in 3 different videotape feedback model groups (expert only, self only, combination of expert and self) and a nonfeedback group were collected while participants performed a basketball jump-landing task on 3 testing occasions. RESULTS: All feedback groups significantly increased knee angular displacement flexion angles [F(6,70) = 8.03, P = .001] and decreased peak vertical ground reaction forces [F(6,78) = 2.68, P = .021] during performance and retention tests. The self and combination groups significantly increased knee angular displacement flexion angles more than the control group did; the expert model group did not change significantly more than the control group did. All feedback groups and the nonfeedback group significantly reduced peak vertical forces across performance and retention tests. There were no statistically significant changes in knee flexion angle at initial ground contact (P = .111) and peak proximal anterior tibial shear forces (P = .509) for both testing sessions for each group. CONCLUSION: The use of self or combination videotape feedback is most useful for increasing knee angular displacement flexion angles and reducing peak vertical forces during landing. CLINICAL RELEVANCE: The use of self or combination modeling is more effective than is expert-only modeling for the implementation of instructional programs aimed at reducing the risk of jump-landing anterior cruciate ligament injuries.

Adolescent↗
PubMed2005

Effect of fatigue on knee kinetics and kinematics in stop-jump tasks.

BACKGROUND: Altered motor control strategies in landing and jumping maneuvers are a potential mechanism of noncontact anterior cruciate ligament injury. There are biomechanical differences between male and female athletes in the landing phase of stop-jump tasks. Fatigue is a risk factor in musculoskeletal injuries. HYPOTHESIS: Lower extremity muscle fatigue alters the knee kinetics and kinematics during the landing phase of 3 stop-jump tasks and increases an athlete's risk of anterior cruciate ligament injury. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional videography and force plate data were collected for 20 recreational athletes (10 male and 10 female athletes) performing 3 stop-jump tasks before and after completing a fatigue exercise. Knee joint angles and resultant forces and moments were calculated. RESULTS: Both male and female subjects had significantly increased peak proximal tibial anterior shear forces (P = .01), increased valgus moments (P = .03), and decreased knee flexion angles (P = .03) during landings of all 3 stop-jump tasks when fatigued. Fatigue did not significantly affect the peak knee extension moment for male or female athletes. CONCLUSION: Fatigued recreational athletes demonstrate altered motor control strategies, which may increase anterior tibial shear force, strain on the anterior cruciate ligament, and risk of injury for both female and male subjects. CLINIC RELEVANCE: Fatigued athletes may have an increased risk of noncontact anterior cruciate ligament injury.

Adult↗
PubMed2005

MRI appearance of chondral delamination injuries of the knee.

OBJECTIVE: We describe the MRI appearance of five cases of chondral delamination of the knee. CONCLUSION: Chondral delamination injuries of the knee show increased linear signal abnormality at the junction of the articular cartilage and subchondral bone on T2-weighted (fast spin-echo) images of the knee. Identifying and treating these lesions results in an improved prognosis for patients with this injury.

Adolescent↗
PubMed2004

Immediate effects of a knee brace with a constraint to knee extension on knee kinematics and ground reaction forces in a stop-jump task.

BACKGROUND: A small knee flexion angle in landing tasks was identified as a possible risk factor for noncontact anterior cruciate ligament injuries that are common in sports. HYPOTHESIS: A specially designed knee brace with a constraint to knee extension would significantly increase the knee flexion angle at the landing of athletic tasks preceded with horizontal movement components, such as stop-jump tasks. STUDY DESIGN: Repeated measure design for brace effects. METHODS: Three-dimensional videographic and force plate data were collected for 10 male and 10 female recreational athletes performing a stop-jump task with and without the specially designed brace. Knee flexion angle at landing, maximum knee flexion angle, and peak ground reaction forces during the stance phase of the stop-jump task were determined for each subject with and without the knee brace. RESULTS: The knee brace decreased the knee flexion angle at the landing by 5 degrees for both genders but did not significantly affect the peak ground reaction forces during the landing. CONCLUSIONS: The specially designed knee brace may be a useful device in the prevention and rehabilitation of noncontact anterior cruciate ligament injuries in sports.

Adolescent↗
PubMed2004

Nandrolone decanoate and load increase remodeling and strength in human supraspinatus bioartificial tendons.

BACKGROUND: To date, no studies document the effect of anabolic steroids on rotator cuff tendons. STUDY DESIGN: Controlled laboratory study. HYPOTHESIS: Anabolic steroids enhance remodeling and improve the biomechanical properties of bioartificially engineered human supraspinatus tendons. METHODS: Bioartificial tendons were treated with either nandrolone decanoate (nonload, steroid, n = 18), loading (load, nonsteroid, n = 18), or both (load, steroid, n = 18). A control group received no treatment (nonload, nonsteroid [NLNS], n = 18). Bioartificial tendons' remodeling was assessed by daily scanning, cytoskeletal organization by staining, matrix metalloproteinase-3 levels by ELISA assay, and biomechanical properties by load-to-failure testing. RESULTS: The load, steroid group showed the greatest remodeling and the best organized actin cytoskeleton. Matrix metallo-proteinase-3 levels in the load, steroid group were greater than those of the nonload, nonsteroid group (P <.05). Ultimate stress and ultimate strain in the load, steroid group were greater than those of the nonload, nonsteroid and nonload, steroid groups (P <.05). The strain energy density in the load, steroid group was greater when compared to other groups (P <.05). CONCLUSIONS: Nandrolone decanoate and load acted synergistically to increase matrix remodeling and biomechanical properties of bioartificial tendons. CLINICAL RELEVANCE: Data suggest anabolic steroids may enhance production of bioartificial tendons and rotator cuff tendon healing in vitro. More research is necessary before such clinical use is recommended.

Adult↗
PubMed2002

Clinical perspectives regarding eccentric muscle injury.

Muscle strain injuries occur to predictable muscles at consistent locations during expected sporting maneuvers when a muscle is stretched and then activated, particularly during high intensity bursts of activity. More than 30% of the injuries seen in the clinician's office are injuries to skeletal muscle. The typical location of the injury is just proximal to the distal muscle tendon junction regardless of strain rate or architecture of the muscle. After the injury, the muscle is weaker, continues to weaken, then recovers during the next week. An inflammatory response is seen in the following 1 to 2 days. By the seventh day, fibrous tissue replaces the inflammatory reaction and a scar forms. When a muscle is stretched, its tension still is reduced making the healing muscle more susceptible to a repeat injury. Viscoelastic properties of muscle also can help explain how muscle can be protected against strain injury. A 1 degree C increase in muscle temperature (warm-up) increases the muscle length to failure and a fatigued muscle is more susceptible to strain injury. It probably is impossible to prevent muscle strain injury; however, preventive measures can make muscle more resistant to these stretch-induced injuries.

Animals↗
PubMed2002

Femoral head osteochondral lesions in painful hips of athletes: MR imaging findings.

OBJECTIVE: This study describes the MR imaging findings of focal osteochondral lesions found in the hips of 11 athletes with persistent pain and normal findings on radiographs. CONCLUSION: Osteochondral lesions of the femoral head are seen on MR imaging as focal, medial areas of high T2-weighted and low T1-weighted signals and should be considered as a possible cause of persistent hip or groin pain in young, high-level athletes because the institution of appropriate treatment may help to prevent late degenerative sequelae.

Adolescent↗