D Mellifont

Mechanisms of anterior cruciate ligament injuries in elite women’s netball: a systematic video analysis

ABSTRACT This study involved a systematic video analysis of 16 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games in order to describe the game situation, the movement patterns involved, the player’s behaviour, and a potential injury mechanism. Eight of the ACL injuries were classified as “indirect contact” and eight as “non-contact”. Two common scenarios were identified. In Scenario A the player was jumping to receive or intercept a pass and whilst competing for the ball experienced a perturbation in the air. As a result the player’s landing was unbalanced with loading occurring predominantly on the knee of the injured side. In Scenario B the player was generally in a good position at ground contact, but then noticeably altered the alignment of the trunk before the landing was completed. This involved rotating and laterally flexing the trunk without altering the alignment of the feet. Apparent knee valgus collapse on the knee of the injured side was observed in 3/6 Scenario A cases and 5/6 Scenario B cases. Players may benefit from landing training programmes that incorporate tasks that use a ball and include decision-making components or require players to learn to cope with being unbalanced.

Tibial displacement and rotation during seated knee extension and wall squatting: A comparative study of tibiofemoral kinematics between chronic unilateral anterior cruciate ligament deficient and healthy knees

BACKGROUND Following anterior cruciate ligament (ACL) rupture, the knee becomes unstable with alterations in joint kinematics including anterior tibial displacement (ATD), and internal tibial rotation. Therapeutic exercises that promote faulty kinematics should be discouraged, especially early post-reconstruction, to avoid graft stretching and possibly longer-term osteoarthritis. Our study aimed to compare ATD and tibial rotation during two commonly prescribed exercises, namely: open kinetic chain (OKC) seated extension and closed kinetic chain (CKC) single leg wall squatting in ACL-deficient and healthy knees. METHODS Eight ACL-deficient patients and eight healthy subjects matched for age, gender and sports history were assessed using Qualisys 3D-Motion Analysis System to track 17 infrared markers while performing a seated knee extension with 3kg weight and a unilateral wall squat. We developed a model to measure joint kinematics through 70° of knee flexion and extension. ANOVA and paired t-tests compared relative ATD and tibial rotation between exercises and groups at 10° increments of flexion and extension. RESULTS We found increased ATD in the wall squat compared to the seated extension (p=0.049). There was no difference in ATD between the healthy and ACL-deficient knees but overall the tibia was significantly more internally rotated (p=0.003) in ACL-deficient knees, irrespective of the exercise, possibly interfering with the screw-home mechanism. CONCLUSIONS CKC exercises, in particular wall squats, are not necessarily safer for patients with ACL-deficiency and possibly ACL-reconstruction; although generalization should only be made with appropriate caution. Clinicians require a detailed knowledge of the effect of exercise on knee joint kinematics.

Concussion-Driven Dilemmas in Sports Medicine

The case outlined below provides the basis for the “In That Case” section in an upcoming issue of the Journal of Bioethical Inquiry (JBI). We invite interested readers to provide responses to the case for possible publication. Responses should be 500–700 words in length (although longer pieces will be considered) and submitted as soon as possible. The editors will select the responses to be published and reserve the right to edit contributions to avoid repetition. Editorial changes will be cleared with authors before going to press. Responses should be submitted via Editorial Manager.

Wrist Injuries in Tennis Players: A Narrative Review

The wrist/hand complex forms the crucial final link in the kinetic chain between the body and the racquet and therefore has a number of important roles in the production of all tennis strokes. However, the internal and external loads that are created at the wrist during these strokes have the potential to contribute to pain and injury. Therefore, the purposes of this narrative review are to (1) determine the extent of the problem of wrist pain/injury in tennis players, (2) identify bony and soft tissue structures of the wrist that are susceptible to damage as a result of tennis play and (3) explore factors that may influence the development of wrist pain/injury in tennis players. The epidemiological data revealed two important points. First, some evidence suggests wrist pain/injury accounts for a higher percentage of total injuries in more recent studies (2014–2015) than in early studies (1986–1995). Second, the relative frequency of wrist pain/injury compared with other well-recognized problem areas for tennis players such as the shoulder complex, elbow and lumbar spine is noticeably higher in more recent studies (2014–2015) than in early studies (1986–1995), particularly among females. Collectively, this would seem to indicate that the problem of wrist pain/injury has increased in the modern game. In fact, some wrist injuries appear to be related to the use of certain forehand grip types and the predominant use of the two-handed backhand. While the loads experienced at the wrist during tennis stroke production seem to be below threshold levels for a single event, the cumulative effects of these loads through repetition would appear to be an important consideration, especially when inadequate time is allowed to complete normal processes of repair and adaptation. This is supported by the evidence that most wrist injuries in tennis are associated with overuse and a chronic time course. The complex interaction between load, repetition, and training practices in tennis, particularly among young developing players who choose a path of early specialization, needs to be further explored.

Influence of previous groin pain on hip and pelvic instep kick kinematics

ABSTRACT This study analyzed differences in pelvic and hip joint kinematics during maximal instep kicks from two different approach angles in football players with and without previous groin pain (Group C and PGP Group, respectively). Kinematic data were recorded at 500 Hz, from 22 semiprofessional, male football players (age 23 [19–26] years) performing 12 instep kicks from 45° and 60° approach angles. Two-way analysis of variance identified differences between groups, and Cohen’s d determined the magnitude of effect sizes. Foot velocity at impact did not differ significantly between the groups for kicks from the 45° approach angle (P = 0.458, d = 0.13), although both groups slowed significantly at 60° (Group C: P < 0.001, d = 0.87; PGP Group: P < 0.001, d = 0.65). For kicks from the 45° approach angle, numerous significant differences existed between groups in pelvic and hip joint orientations, range of motion and maximal velocities. When kicking from the more acute 60° approach angle, Group C modified multiple aspects of pelvis and hip kinematics, while the PGP Group failed to adapt their technique. During maximal instep, kicking football players with previous groin pain employed different hip and pelvis kinematics to uninjured controls. The kicking kinematics adopted by the PGP group were consistent with aberrant kinetic chain utilization.