Study Design: Methodological study. Objectives: To examine the agreement and validity of using observational risk screening guidelines to evaluate ACL injury risk factors. Background: Post-pubescent females have an increased risk of anterior cruciate ligament (ACL) injury compared with their male counterparts partly due to their high-risk landing and cutting strategies. There are currently no scientifically-tested methods to screen for these high risk strategies in the clinic or on the field. Methods and Measures: Three physiotherapists used observational risk screening guidelines to rate the neuromuscular characteristics of 40 adolescent female soccer players. Drop jumps were rated as high risk or low risk based on the degree of knee abduction. Side hops and side cuts were rated on the degree of lower limb 'reaching'. Ratings were evaluated for intrarater and interrater agreement using kappa coefficients. 3D motion analysis was used as a gold standard for determining the validity of ratings. Results: Acceptable intrarater and interrater agreement (k≥0.61) were attained for the drop jump and the side hop, with kappa coefficients ranging from 0.64 to 0.94. Acceptable sensitivity (≥0.80) was attained for the side hop and the side cut, with values ranging from 0.88 to 1.00. Acceptable specificity (≥0.50) was attained for the drop jump, with values ranging from 0.64 to 0.72. Conclusion: Observational risk screening is a practical and cost-effective method of screening for ACL injury risk. Based on levels of agreement and sensitivity, the side hop appears to be a suitable screening task. Agreement was acceptable for the drop jump but its validity needs further investigation.

"This research aimed to explore and better understand intervention protocols and their effect on lower limb control associated with anterior cruciate ligament (ACL) injury. A fundamental and unique aspect of this investigation was to establish a lab-based testing protocol that successfully mimicked actual game play. [...]This research validated a lab-based measure that best mimicked game-play to use as a pre- and post- testing measure for two common methods used in current ACL intervention strategies. In addition, further understanding of the effects of a landing training and dynamic balance training program were found." / Doctor of Philosphy

"This research aimed to explore and better understand intervention protocols and their effect on lower limb control associated with anterior cruciate ligament (ACL) injury. A fundamental and unique aspect of this investigation was to establish a lab-based testing protocol that successfully mimicked actual game play. [...]This research validated a lab-based measure that best mimicked game-play to use as a pre- and post- testing measure for two common methods used in current ACL intervention strategies. In addition, further understanding of the effects of a landing training and dynamic balance training program were found." / Doctor of Philosphy

Female athletes are known to have a higher rate of ACL injuries than male athletes in similar sports. Anatomical, neuromuscular, and strength factors have all been proposed as potential causes of this difference. The purpose of this investigation was to determine, through a series of three studies, the magnitude of sex differences, which exist in these potential risk factors. The first study investigated sex differences in anatomical risk factors. Male and female athletes from the Queensland Academy of Sport (Basketball: M = 14; F = 16; Soccer: F = 14) as well as the Men’s Lions Soccer club (n = 10) were recruited to participate in the study. A physical examination was completed which included: anthropometric measurements; lower extremity alignment measurements such as Q-Angle, knee recurvatum, and foot pronation; knee ligamentous laxity and muscle flexibility measurements; intercondylar notch width measurements using MRI; and an orthopedic examination. Our investigation found that anatomical differences do exist between healthy uninjured male and females. Females had larger Q-Angles, excessive foot pronation, decreased intercondylar notch width and increased ligamentous laxity and muscular flexibility compared to males. However, when examining the likely magnitude of these difference between the sexes, only a moderate effect was found (0.60 < ES ≤ 1.2). The second study investigated sex differences in strength measures that included knee flexion and extension peak torque values as measured using an isokinetic dynamometer, thigh muscle volume and cross sectional area (CSA) determined by Magnetic Resonance Imaging (MRI), and single leg hop for distance. Male and female athletes were recruited from the Queensland Academy of Sport (QAS) basketball program (M= 13; F = 13). Males were found to be significantly stronger than females even when all strength measurements were normalized to account for sex differences in anthropometrics (p < 0.05). Males generated greater peak forces in their knee extensors and flexors, greater hop distances and had larger muscle volumes and maximal cross sectional areas as determined by MRI analysis. When examining the likely magnitude of these difference between the sexes, a moderate to large effect was found (1.00 < ES ≤ 2.8). The final study investigated sex differences in lower limb neuromuscular factors, viz: body-segmental motions; ground reaction forces; and muscle timing and recruitment patterns in response to a drop-landing task in a laboratory setting. Participants recruited for the study were male and female university students (M= 11, F = 11), currently attending the University of Queensland. Participants performed a drop-landing task that consisted of performing a total of eight vertical drop landings from a box, 40cm in height, onto a force platform. Lower extremity sagittal plane marker kinetics and kinematics for the hip, knee and ankle were collected to determine joint angles at impact of landing and then maximum angle reached, ROM from initial ground contact to maximum angle as well as joint angular velocities. Thigh muscle activation patterns (i.e. recruitment order) in response to the drop-landing task were also collected. Results found that the female group landed with decreased knee flexion angles and higher ground reaction forces per body weight during the impact of landing compared to the males. After initial impact, the females also reached the greatest angles at the hip and knee therefore producing the greatest ROM at these joints. In regards to thigh muscle activation patterns, both male and female groups activated the hamstring muscles, prior to quadriceps activation, a result that was not expected. In conclusion, several anatomical, neuromuscular and strength differences exist between male and female athletes with the greatest differences observed in the kinematic and strength data. Females could potentially best benefit from training programs that include strength and proprioception components as well as technique awareness in an attempt to reduce the current ACL incidence rates observed in female athletes.

Doctor of Philosophy / The aim of the work presented in this thesis was to examine the associations between the kinematics of the knee characterised by the tibiofemoral contact pattern, and degenerative change, in the context of anterior cruciate ligament (ACL) injury. While the natural history of degenerative change following knee injury is well understood, the role of kinematics in these changes is unclear. Kinematics of the knee has been described in a variety of ways, most commonly by describing motion according to the six degrees of freedom of the knee. The advantage of mapping the tibiofemoral contact pattern is that it describes events at the articular surface, important to degenerative change. It was hypothesised that the tibiofemoral contact pattern would be affected by injury to the knee. A model of ACL injury was chosen because the kinematics of the knee have been shown to be affected by ACL injury, and because the majority of chronic ACL-deficient knees develop osteoarthritis, the associations between kinematics and degenerative change could be explored. A technique of tibiofemoral contact pattern mapping was established using MRI, as a quantifiable measure of knee kinematics. The tibiofemoral contact pattern was recorded from 0º to 90º knee flexion while subjects performed a leg-press against a 150N load, using sagittal magnetic resonance imaging (MRI) scans. The technique was tested and found to be reliable, allowing a description of the tibiofemoral contact pattern in 12 healthy subjects. The tibiofemoral contact patterns of knee pathology were then examined in a series of studies of subjects at a variety of stages of chronicity of ligament injury and osteoarthritis. Twenty subjects with recent ACL injury, 23 subjects with chronic ACL deficiency of at least 10 years standing, and 14 subjects with established osteoarthritis of the knee were recruited. The 20 subjects with recent ACL injury were examined again at 12 weeks and 2 years following knee reconstruction. The tibiofemoral contact patterns were examined for each group of subjects and the associations between changes in the contact patterns and evidence of joint damage explored. Evidence of joint damage and severity of osteoarthritis were recorded from xrays, diagnostic MRI, operation reports and bone densitometry at the tibial and femoral condyles of the knee. Each of the three groups with knee pathology exhibited different characteristics in the tibiofemoral contact pattern, and these differences were associated with severity of joint damage and osteoarthritis. The recently ACL-injured knees demonstrated a tibiofemoral contact pattern that was posterior on the tibial plateau, particularly in the lateral compartment. Those with chronic ACL deficiency demonstrated differences in the contact pattern in the medial compartment, associated with severity of damage to the knee joint. Osteoarthritic knees showed reduced femoral roll back and longitudinal rotation that normally occur during knee flexion. Two years following knee reconstruction there was no difference between the contact pattern of the reconstructed and healthy contralateral knees. This technique of tibiofemoral contact pattern mapping is sensitive to the abnormal characteristics of kinematics in ligament injury and osteoarthritis. This is the first time the tibiofemoral contact characteristics of chronic ACL-deficient and osteoarthritis knees have been described and links examined between tibiofemoral contact patterns and degenerative change.

Doctor of Philosophy / The aim of the work presented in this thesis was to examine the associations between the kinematics of the knee characterised by the tibiofemoral contact pattern, and degenerative change, in the context of anterior cruciate ligament (ACL) injury. While the natural history of degenerative change following knee injury is well understood, the role of kinematics in these changes is unclear. Kinematics of the knee has been described in a variety of ways, most commonly by describing motion according to the six degrees of freedom of the knee. The advantage of mapping the tibiofemoral contact pattern is that it describes events at the articular surface, important to degenerative change. It was hypothesised that the tibiofemoral contact pattern would be affected by injury to the knee. A model of ACL injury was chosen because the kinematics of the knee have been shown to be affected by ACL injury, and because the majority of chronic ACL-deficient knees develop osteoarthritis, the associations between kinematics and degenerative change could be explored. A technique of tibiofemoral contact pattern mapping was established using MRI, as a quantifiable measure of knee kinematics. The tibiofemoral contact pattern was recorded from 0º to 90º knee flexion while subjects performed a leg-press against a 150N load, using sagittal magnetic resonance imaging (MRI) scans. The technique was tested and found to be reliable, allowing a description of the tibiofemoral contact pattern in 12 healthy subjects. The tibiofemoral contact patterns of knee pathology were then examined in a series of studies of subjects at a variety of stages of chronicity of ligament injury and osteoarthritis. Twenty subjects with recent ACL injury, 23 subjects with chronic ACL deficiency of at least 10 years standing, and 14 subjects with established osteoarthritis of the knee were recruited. The 20 subjects with recent ACL injury were examined again at 12 weeks and 2 years following knee reconstruction. The tibiofemoral contact patterns were examined for each group of subjects and the associations between changes in the contact patterns and evidence of joint damage explored. Evidence of joint damage and severity of osteoarthritis were recorded from xrays, diagnostic MRI, operation reports and bone densitometry at the tibial and femoral condyles of the knee. Each of the three groups with knee pathology exhibited different characteristics in the tibiofemoral contact pattern, and these differences were associated with severity of joint damage and osteoarthritis. The recently ACL-injured knees demonstrated a tibiofemoral contact pattern that was posterior on the tibial plateau, particularly in the lateral compartment. Those with chronic ACL deficiency demonstrated differences in the contact pattern in the medial compartment, associated with severity of damage to the knee joint. Osteoarthritic knees showed reduced femoral roll back and longitudinal rotation that normally occur during knee flexion. Two years following knee reconstruction there was no difference between the contact pattern of the reconstructed and healthy contralateral knees. This technique of tibiofemoral contact pattern mapping is sensitive to the abnormal characteristics of kinematics in ligament injury and osteoarthritis. This is the first time the tibiofemoral contact characteristics of chronic ACL-deficient and osteoarthritis knees have been described and links examined between tibiofemoral contact patterns and degenerative change.

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, Ortopedi ve Travmatoloji Anabilim Dalı, 2004. / Bibliyografya var.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser. - På omsl. felaktigt: Karolinska University Press.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (M.S.)--Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.