Knee wobbling during the single-leg-squat-and-hold test reflects dynamic knee instability in patients with anterior cruciate ligament injury

We propose using the single-leg squat-and-hold (SLSH) task with kinematic analysis to objectively measure dynamic knee stability after anterior cruciate ligament (ACL) injury. There are three objectives of this study: to compare the knee kinematics of ACL-deficient patients and healthy controls by capturing knee wobbling during the SLSH task, to detect kinematic changes after ACL reconstruction, and to correlate the kinematic variables with self-reported knee function. Twenty-five ACL-deficient participants and 18 healthy matched participants were recruited. The knee kinematics involving both the magnitudes and frequency of motion fluctuation was captured during SLSH by 3D motion analysis system (Vicon). Compared to the limbs of the control participants, the ACL involved limbs exhibited a greater range of flexion-extension (4.33 ± 1.96 vs. 2.73 ± 1.15; p = 0.005) and varus-valgus (2.52 ± 0.99 vs. 1.36 ± 0.42; p < 0.001). It also inhibited higher frequency of flexion-extension (4.87 ± 2.55 vs. 2.68 ± 1.23; p = 0.003) and varus-valgus (3.83 ± 2.59 vs. 1.42 ± 0.55; p < 0.001). The range of flexion-extension (4.50 ± 2.24 vs. 2.90 ± 1.01; p = 0.018), frequency of flexion-extension (4.58 ± 2.53 vs. 3.05 ± 1.80; p = 0.038) and varus-valgus (3.46 ± 2.11 vs. 1.80 ± 1.23; p = 0.022) was reduced after ACL reconstruction. Increased frequency of knee varus-valgus was correlated with lower IKDC score (r = -0.328; p = 0.034). Knee wobbling was more prominent in ACL-deficient patients, which was associated with poor knee function. SLSH task with kinematic analysis appears to be a potential assessment method for monitoring dynamic knee stability after ACL injury.

Secondary Anterior Cruciate Ligament Injury Prevention Training in Athletes: What Is the Missing Link?

After reconstruction, the return to full competition rate of athletes is low, while the re-injury rate remains high despite the completion of a rehabilitation programme. Primary ACL prevention programmes are well developed, yet few research papers focus on secondary ACL injury prevention. The aim of current review is to determine if current ACL secondary prevention training has a positive influence on the re-injury rate, the clinical or functional outcomes, or the risk of re-injury in athletes. Studies investigating secondary prevention of ACL were searched in PubMed and EBSCOhost, followed by a review of the references in the identified articles. The existing evidence suggests that neuromuscular training, eccentric strengthening, and plyometric exercises may have a potential impact on improving biomechanical, functional, and psychological outcomes in athletes; however, the studies on the prevention of second ACL injury in athletes is scarce and inconclusive. Future research is needed to investigate the effectiveness of secondary ACL prevention in reducing the re-injury rates. (PROSPERO Registration number: CRD42021291308).

A lateral ankle sprain during a lateral backward step in badminton: A case report of a televised injury incident

BACKGROUND

This study presents a kinematic analysis of an acute lateral ankle sprain incurred during a televised badminton match. The kinematics of this injury were compared to those of 19 previously reported cases in the published literature.

METHODS

Four camera views of an acute lateral ankle sprain incurred during a televised badminton match were synchronized and rendered in 3-dimensional animation software. A badminton court with known dimensions was built in a virtual environment, and a skeletal model scaled to the injured athlete's height was used for skeletal matching. The ankle joint angle and angular velocity profiles of this acute injury were compared to the summarized findings from 19 previously reported cases in the published literature.

RESULTS

At foot strike, the ankle joint was 2° everted, 33° plantarflexed, and 18° internally rotated. Maximum inversion of 114° and internal rotation of 69° was achieved at 0.24 s and 0.20 s after foot strike, respectively. After the foot strike, the ankle joint moved from an initial position of plantarflexion to dorsiflexion-from 33° plantarflexion to 53° dorsiflexion (range = 86°). Maximum inversion, dorsiflexion, and internal rotation angular velocity were 1262°/s, 961°/s, and 677°/s, respectively, at 0.12 s after foot strike.

CONCLUSION

A forefoot landing posture with a plantarflexed and internally rotated ankle joint configuration could incite an acute lateral ankle sprain injury in badminton. Prevention of lateral ankle sprains in badminton should focus on the control and stability of the ankle joint angle during forefoot landings, especially when the athletes perform a combined lateral and backward step.

What have we learnt from quantitative case reports of acute lateral ankle sprains injuries and episodes of 'giving-way' of the ankle joint, and what shall we further investigate?

Lateral ankle sprains are a commonly incurred injury in sports. They have a high recurrence rate and can lead to the development of persistent injury associated symptoms. We performed a quantitative synthesis of published case reports documenting the kinematics of acute lateral ankle sprains and episodes of 'giving-way' of the ankle joint to provide a comprehensive description of the mechanisms. A systematic literature search was conducted to screen records within MEDLINE® and EMBASE®. Additional strategies included manual search of specific journals, as well as contacting researchers in relevant communities to retrieve unpublished data. Twenty-four cases were included in the quantitative synthesis, 11 from individual case reports and 13 from four separate case series. Two authors independently reviewed all the articles and extracted ankle joint kinematic data. Excessive ankle inversion was the most pronounced kinematic pattern observed across all included cases, with a mean peak inversion angle of 67.5° (range 2.0 to 142) and a mean peak inversion velocity of 974°/s (range 468 to 1752). This was followed by internal rotation and plantar flexion, respectively. A homogeneous linear function revealed a mean inversion velocity across all cases of 337°/s (range 117 to 1400; R² = 0.78; p < 0.0001).

An inverted ankle joint orientation at foot strike could incite ankle inversion sprain: Comparison between injury and non-injured cutting motions of a tennis player

Ankle sprain is very common in sports. Research on its prevention is as important as on its treatment as recommended in the 2016 consensus statement of the International Ankle Consortium. Successful prevention depends on the understanding of its mechanism, which has been presented with quantities in some recent case reports. Inciting event was suggested to be an inverted ankle joint at foot strike, however, is still lacking evidence from comparison with non-injury trials. This study investigated the ankle joint orientation at foot strike in successful non-injury cases and compared them with a previously analysed ankle sprain injury case. Two injury-free cutting motions with similar movement approach to a previously analysed ankle sprain injury performed by the same athlete were collected from an online search and were trimmed from 0.05 s before until 0.30 s after the foot strike. The video sequences were then processed by video editing software and then analysed by a model-based image-matching motion analysis technique. Ankle joint orientation at foot strike and the profiles were presented in inversion, plantarflexion and rotation planes, for both the previously analysed injury case and the two non-injury cases. The ankle joint orientation at foot strike was 0-1 degree inverted and 10-21° dorsiflexed in the two non-injury cases, compared to 14° inverted and 16° plantarflexed in the previously analysed injury case. From the case comparison, it can be observed that an inverted ankle joint orientation at foot strike in an inciting event of ankle inversion sprain.

Kiss goodbye to the 'kissing knees': no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes

The aim of this study was to investigate if frontal plane knee and hip control in single-leg squats or vertical drop jumps with an overhead target were associated with future non-contact anterior cruciate ligament (ACL) injury in elite female athletes. Of the 429 handball and 451 football athletes (age 21.5 ± 4.0 years, height 169.6 ± 6.4 cm, body weight 67.1 ± 8.0 kg), 722 non-injured and 56 non-contact ACL injured participants were eligible for analysis. We calculated lateral pelvic tilt, frontal plane knee projection angle, medial knee position, and side-to-side asymmetry in these from 2D videos recorded at baseline, and recorded any new ACL injuries prospectively. None of the aforementioned variables in either screening task were different or could discriminate between injured and non-injured athletes (all p values >.05 and Cohen's d values < .27). Two-dimensional video assessment of frontal plane knee and hip control during both a single-leg squat and vertical drop jump was unable to identify individuals at increased risk of non-contact ACL injury, thus should not be used for screening.

Delayed ankle muscle reaction time in female amateur footballers after the first 15 min of a simulated prolonged football protocol

PURPOSE

Ankle sprain injury rate is reported to be higher towards the end of a football match. Muscle fatigue may contribute to the delayed muscle reaction and subsequent injury. This study investigated the ankle muscle reaction time during a simulated, prolonged football protocol.

METHODS

Seven amateur female football players participated in a 105-min simulated, prolonged football protocol. An ankle muscle reaction test was conducted with a pair of ankle sprain simulators at a scheduled interval every 15-min. The reaction times of peroneus longus, tibialis anterior, and lateral gastrocnemius were collected using an electromyography system sampling at 1000 Hz. Repeated measures one-way multivariate analysis of variance with post-hoc paired t-tests were conducted to evaluate if the reaction time at each time point significantly differed from baseline. Statistical significance was set at p < 0.05 level.

RESULTS

Reaction times started from 40.5-47.7 ms at baseline and increased to 48.6-55.7 ms at the end. Reaction times significantly increased in all muscles after the first 15 min except for the dominant lateral gastrocnemius. Increased reaction times were seen in the non-dominant limb after 60 min for tibialis anterior, after 75 min for peroneus longus, and after 90 min for the lateral gastrocnemius.

CONCLUSIONS

Delayed reaction time of the ankle muscles were found after the first 15 min and in the final 45 min of a simulated prolonged football protocol. Strategies for injury prevention should also focus on tackling the delayed ankle muscle reaction time in the acute phase (the first 15 min), in addition to the latter minutes in the second half.

LEVEL OF EVIDENCE

Controlled laboratory study, Level V.

Development of a road traffic emission inventory with high spatial-temporal resolution in the world's most densely populated region-Macau

With rapid economic growth, road transport is contributing substantial adverse effects on urban air quality, especially in densely populated cities with high growth rate of GDP per capita, such as Macau. A high spatial-temporal resolution road traffic emission inventory is essential for assessment of environmental stresses imposed by local vehicle movements. To improve the accuracy and temporal-spatial resolution for emission inventory, through a bottom-up approach, link-based road traffic emission inventory with a spatial resolution of 0.1 km ∗ 0.1 km and a temporal resolution of 1 h for Macau in 2014 was developed by using a traffic model (VISUM), a road traffic emission model (TREM), the Geographic Information System (GIS), and the most up-to-date information available. Results show that the total annual emissions of CO, CO₂, PM, NO_X, and VOC in 2014 were 14,770, 413,099, 69, 1151, and 2945 tons, respectively. The estimated fuel consumption agreed well also with the statistical fuel consumption in Macau. Meanwhile, analysis of 3 scenarios on changes of road traffic emissions due to the operation of a light railway transit (LRT) system, variation on share of diesel, electric, and gasoline within the vehicle fleet, and replacement of vehicles with ones of Euro 5 and Euro 6 emission standards was carried out. This study provides a solid framework for developing high spatial-temporal resolution emission inventories for other densely populated cities of small area.

Kinematic analysis of a televised medial ankle sprain

Ankle sprains are one of the most prevalent athletic injuries. Prior work has investigated lateral ankle sprains, but research on generally more severe medial sprains is lacking. This case report performs a kinematic analysis using novel motion analysis methods on a non-contact medial ankle sprain. Peak eversion (50°) occurred 0.2 seconds following ground contact, maximum velocity of 426°/s, while peak dorsiflexion (64°) occurred with a greater maximum velocity (573°/s). The combination of dorsiflexion at ground contact and rapid eversion is associated with a non-contact eversion sprain. This study provides a quantitative analysis of the eversion ankle sprain injury mechanism.

Eccentric hamstring strength deficit and poor hamstring-to-quadriceps ratio are risk factors for hamstring strain injury in football: A prospective study of 146 professional players

OBJECTIVES

The purpose of this study was to investigate whether preseason isokinetic strength measures were predictive of future HSI among professional football players.

DESIGN

Prospective cohort study, Level of evidence 2.

METHODS

A total of 169 professional players participated in a preseason isokinetic strength screening, followed by a 10-month competitive season. Testing protocol included the concentric performance of both knee flexion and extension at 60degs^-1 and 240degs^-1 and the eccentric performance of the knee flexor at 30degs^-1. Strength deficits, bilateral differences, and hamstring to quadriceps strength ratios were computed. Univariate and multivariate logistic regressions were used to identify potential risk factors of HSI. Receiver operating characteristic (ROC) curves were used to investigate the sensitivity and specificity of the strength measures.

RESULTS

Forty-one acute HSIs were sustained, and 12% (n=5) reoccurred within the study period. In the multivariate analysis, we have shown an association between the injury risk and eccentric hamstring peak torque below 2.4Nmkg^-1 (OR=5.59; 95% CI, 2.20-12.92); concentric H/Q ratio below 50.5% (OR=3.14; 95% CI, 1.37-2.22); players with previous injury of HSI (OR=3.57; 95% CI, 3.13-8.62). ROC analysis displayed an area under curve (AUC) of 0.77, indicating fair combined sensitivity and specificity of the overall predicting model.

CONCLUSIONS

Professional football players with significant lower isokinetic hamstring strength, lower hamstring-to-quadriceps strength ratio, and a previous injury of HSI were linked to an increased risk of acute HSI.

Reconstruction of head impacts in FIS World Cup alpine skiing

INTRODUCTION

Prior to the 2013/2014 season, the International Ski Federation (FIS) increased the helmet testing speed from 5.4 to 6.8 m/s for alpine downhill, super-G and giant slalom. Whether this increased testing speed reflects head impact velocities in real head injury situations on snow is unclear. We therefore investigated the injury mechanisms and gross head impact biomechanics in seven real head injury situations among World Cup (WC) alpine skiers.

METHODS

We analysed nine head impacts from seven head injury videos from the FIS Injury Surveillance System, throughout nine WC seasons (2006-2015) in detail. We used commercial video-based motion analysis software to estimate head impact kinematics in two dimensions, including directly preimpact and postimpact, from broadcast video. The sagittal plane angular movement of the head was also measured using angle measurement software.

RESULTS

In seven of nine head impacts, the estimated normal to slope preimpact velocity was higher than the current FIS helmet rule of 6.8 m/s (mean 8.1 (±SD 0.6) m/s, range 1.9±0.8 to 12.1±0.4 m/s). The nine head impacts had a mean normal to slope velocity change of 9.3±1.0 m/s, range 5.2±1.1 to 13.5±1.3 m/s. There was a large change in sagittal plane angular velocity (mean 43.3±2.9 rad/s (range 21.2±1.5 to 64.2±3.0 rad/s)) during impact.

CONCLUSION

The estimated normal to slope preimpact velocity was higher than the current FIS helmet rule of 6.8 m/s in seven of nine head impacts.

Social psychological aspects of ACL injury prevention and rehabilitation: An integrated model for behavioral adherence

Managing rehabilitation for ACL injury is dependent on uptake of, and compliance with, medical and safety recommendations. In this paper, we propose a multi-theory model that integrates self-determination theory and the theory of planned behavior to identify the motivational determinants ACL injury prevention and management behaviors and the processes involved.

Head impact velocities in FIS World Cup snowboarders and freestyle skiers: Do real-life impacts exceed helmet testing standards?

Introduction

Prior to the 2013–2014 season, the International Ski Federation (FIS) increased the helmet testing speed from a minimum requirement of 5.4 to 6.8 m/s for alpine downhill, super-G and giant slalom and for freestyle ski cross, but not for the other freestyle disciplines or snowboarding. Whether this increased testing speed reflects impact velocities in real head injury situations on snow is unclear. We therefore investigated the injury mechanisms and gross head impact biomechanics in four real head injury situations among World Cup (WC) snowboard and freestyle athletes and compared these with helmet homologation laboratory test requirements. The helmets in the four cases complied with at least European Standards (EN) 1077 (Class B) or American Society for Testing and Materials (ASTM) F2040.

Methods

We analysed four head injury videos from the FIS Injury Surveillance System throughout eight WC seasons (2006–2014) in detail. We used motion analysis software to digitize the helmet’s trajectory and estimated the head’s kinematics in two dimensions, including directly preimpact and postimpact.

Results

All four impacts were to the occiput. In the four cases, the normal-to-slope preimpact velocity ranged from 7.0(±SD 0.2) m/s to 10.5±0.5 m/s and the normal-to-slope velocity change ranged from 8.4±0.6 m/s to 11.7±0.7 m/s. The sagittal plane helmet angular velocity estimates indicated a large change in angular velocity (25.0±2.9 rad/s to 49.1±0.3 rad/s).

Conclusion

The estimated normal-to-slope preimpact velocity was higher than the current strictest helmet testing rule of 6.8 m/s in all four cases.

Comparison of treatment effects on lateral epicondylitis between acupuncture and extracorporeal shockwave therapy

Background

Lateral epicondylitis is one of the most common overuse injuries, and has been reported to reduce function and affect daily activities. There is no standard therapy for lateral epicondylitis. In Hong Kong, acupuncture and extracorporeal shockwave therapy (ESWT) have been popular in treating lateral epicondylitis in recent years.

Objective

This study is to compare the treatment effects of acupuncture and ESWT on lateral epicondylitis.

Methods

In this study, we evaluated 34 patients (34 elbows) with lateral epicondylitis. Seventeen patients were treated by 3-week ESWT, one session per week. Another 17 were treated by 3-week acupuncture therapy, two sessions per week. The outcome measures included pain score by visual analogue scale, maximum grip strength by Jamar dynamometer, and level of functional impairment by disability of arms, shoulders, and hands questionnaire. Participants were assessed at three time points: baseline; after treatment; and 2-week follow-up.

Results

The two treatments showed no significant difference at any assessment time-point. Both treatment groups had significant improvement in pain score in longitudinal comparisons. No significant difference was found in maximum grip strength and functional impairment in either treatment group, but a trend of improvement could be observed. In addition, improvement in pain relief stopped when treatment ended for either groups.

Conclusions

The treatment effects of acupuncture and ESWT on lateral epicondylitis were similar. The pain relief persisted for at least two weeks after treatment.

Measurement of movement patterns to enhance ACL injury prevention - A dead end?

Vertical drop jump has been suggested to be an effective movement screening task for ACL injury risk, but recent studies have questioned the ability of such tasks to accurately identify players with increased risk of injury. In this paper, we discuss the usefulness of movement screening tests from an injury prevention perspective.

Use of a portable motion analysis system for knee dynamic stability assessment in anterior cruciate ligament deficiency during single-legged hop landing

Background/objective

Anterior cruciate ligament (ACL) rupture results in knee instability, and patients are often unable to return to their previous level of activity. Current assessments rely on passive laxity tests, which do not correlate with function. Dynamic stability may be a better indicator for return to sport. However, equipment for measuring dynamic stability is ill suited for clinical use. The purpose of this study is to evaluate knee kinematics in ACL-deficient patients with a single-legged hop task using a portable motion analysis system. We hypothesize that the assessment task is able to differentiate ACL-deficient knees from healthy knees.

Methods

Ten ACL-deficient patients and 10 healthy controls were recruited. Participants were instructed to perform a single-legged hop, while kinematics was measured using a portable motion capture system (Opti-Knee; Shanghai Innomotion Inc., Shanghai, China). Kinematic changes after initial contact were examined. Repeatability of the results was examined by calculating the coefficient of variations of the pooled standard deviation of the tibiofemoral displacements. Side-to-side differences were calculated and compared between the two groups.

Results

One patient could not perform the task. Intraindividual variability was small after initial contact; the coefficient of variation in this region was 13-26%. ACL-deficient knees demonstrated lower flexion range of motion (p = 0.008) and increased internal/external rotation range of motion after landing (p = 0.038), while no significant differences were detected in the healthy group. Only the side-to-side difference in flexion was significantly different between the two groups (p = 0.002).

Conclusion

The altered knee kinematics in ACL-deficient patients can be revealed by a portable motion capture system, which may enable the clinical application of kinematic assessment in the evaluation of ACL deficiency.

Reliability of knee biomechanics during a vertical drop jump in elite female athletes

The purpose of the study was to assess the within-session and between-session reliability of knee kinematics and kinetics in a vertical drop jump task among elite female handball and football athletes. Specifically, we aimed to quantify the within-session waveform consistency and between-session consistency of the subject ranking for a variety of knee kinematics and kinetics. Forty-one elite female handball and football (soccer) athletes were tested in two sessions. The reliability of three-dimensional knee biomechanical measurements was quantified by the intra-class correlation, Spearman's rank correlation, and typical error. All the selected discrete variables achieved excellent within-session reliability (ICC>0.87). The typical error of valgus angles, internal rotation angles, and internal rotation moment was constant throughout the whole stance phase. For between-session reliability, the selected discrete variables achieved good to excellent reliability (ICC>0.69), except peak internal rotation moment (ICC=0.40). All between-session rank correlation coefficients ranged from 0.56 to 0.90. Most of the discrete variables achieved good to excellent reliability in both within-session and between-session analysis. Moreover, moderate to strong between-session consistency of subject rankings was found, implying that the measurements assessed during the vertical drop jump demonstrate sufficient reliability to be used in both single-session and multiple-session studies.

The Vertical Drop Jump Is a Poor Screening Test for ACL Injuries in Female Elite Soccer and Handball Players: A Prospective Cohort Study of 710 Athletes

BACKGROUND

The evidence linking knee kinematics and kinetics during a vertical drop jump (VDJ) to anterior cruciate ligament (ACL) injury risk is restricted to a single small sample. Still, the VDJ test continues to be advocated for clinical screening purposes.

PURPOSE

To test whether 5 selected kinematic and kinetic variables were associated with future ACL injuries in a large cohort of Norwegian female elite soccer and handball players. Furthermore, we wanted to assess whether the VDJ test can be recommended as a screening test to identify players with increased risk.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Elite female soccer and handball players participated in preseason screening tests from 2007 through 2014. The tests included marker-based 3-dimensional motion analysis of a drop-jump landing. We followed a predefined statistical protocol in which we included the following candidate risk factors in 5 separate logistic regression analyses, with new ACL injury as the outcome: (1) knee valgus angle at initial contact, (2) peak knee abduction moment, (3) peak knee flexion angle, (4) peak vertical ground-reaction force, and (5) medial knee displacement.

RESULTS

A total of 782 players were tested (age, 21 ± 4 years; height, 170 ± 7 cm; body mass, 67 ± 8 kg), of which 710 were included in the analyses. We registered 42 new noncontact ACL injuries, including 12 in previously ACL-injured players. Previous ACL injury (relative risk, 3.8; 95% CI, 2.1-7.1) and medial knee displacement (odds ratio, 1.40; 95% CI, 1.12-1.74 per 1-SD change) were associated with increased risk for injury. However, among the 643 players without previous injury, we found no association with medial knee displacement. A receiver operating characteristic curve analysis of medial knee displacement showed an area under the curve of 0.6, indicating a poor-to-failed combined sensitivity and specificity of the test, even when including previously injured players.

CONCLUSION

Of the 5 risk factors considered, medial knee displacement was the only factor associated with increased risk for ACL. However, receiver operating characteristic curve analysis indicated a poor combined sensitivity and specificity when medial knee displacement was used as a screening test for predicting ACL injury. For players with no previous injury, none of the VDJ variables were associated with increased injury risk.

CLINICAL RELEVANCE

VDJ tests cannot predict ACL injuries in female elite soccer and handball players.

Application of a tri-axial accelerometer to estimate jump frequency in volleyball

Patellar tendinopathy is prevalent among athletes, and most likely associated with a high jumping load. If methods for estimating jump frequency were available, this could potentially assist in understanding and preventing this condition. The objective of this study was to explore the possibility of using peak vertical acceleration (PVA) or peak resultant acceleration (PRA) measured by an accelerometer to estimate jump frequency. Twelve male elite volleyball players (22.5 ± 1.6 yrs) performed a training protocol consisting of seven typical motion patterns, including jumping and non-jumping movements. Accelerometer data from the trial were obtained using a tri-axial accelerometer. In addition, we collected video data from the trial. Jump-float serving and spike jumping could not be distinguished from non-jumping movements using differences in PVA or PRA. Furthermore, there were substantial inter-participant differences in both the PVA and the PRA within and across movement types (p < 0.05). These findings suggest that neither PVA nor PRA measured by a tri-axial accelerometer is an applicable method for estimating jump frequency in volleyball. A method for acquiring real-time estimates of jump frequency remains to be verified. However, there are several alternative approaches, and further investigations are needed.

Kinematics of anterior cruciate ligament ruptures in World Cup alpine skiing: 2 case reports of the slip-catch mechanism

BACKGROUND

Based on visual video analyses of 20 injury situations, the main mechanism of anterior cruciate ligament (ACL) injury in World Cup alpine skiing, termed the "slip-catch" mechanism, was identified. This situation is characterized by a common pattern in which the inside edge of the outer ski catches the snow surface while turning, forcing the knee into valgus and tibial internal rotation. To describe the exact joint kinematics at the time of injury, a more sophisticated approach is needed.

PURPOSE

To describe the knee and hip kinematics in 2 slip-catch situations utilizing a model-based image-matching (MBIM) technique.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Two typical slip-catch situations in World Cup alpine skiing reported through the International Ski Federation (FIS) Injury Surveillance System were captured on video with several camera views and high video quality. The injury situations were analyzed using the MBIM technique to produce continuous measurements of knee and hip joint kinematics.

RESULTS

Within 60 milliseconds, the knee flexion angle increased rapidly from 26° to 63° in case 1 and from 39° to 69° in case 2. In the same period, we observed a rapid increase in internal rotation of the tibia with a peak of 12° and 9°, respectively. The knee valgus angle changed less markedly in both cases. We also observed a rapid increase of hip flexion as well as substantial hip internal rotation.

CONCLUSION

Knee compression and knee internal rotation and abduction torque are important components of the injury mechanism in a slip-catch situation.

CLINICAL RELEVANCE

Prevention efforts should focus on avoiding a forceful tibial internal rotation in combination with knee valgus.

Kinematics analysis of ankle inversion ligamentous sprain injuries in sports: five cases from televised tennis competitions

BACKGROUND

Ankle ligamentous sprain is common in sports. The most direct way to study the mechanism quantitatively is to study real injury cases; however, it is unethical and impractical to produce an injury in the laboratory. A recently developed, model-based image-matching motion analysis technique allows quantitative analysis of real injury incidents captured in televised events and gives important knowledge for the development of injury prevention protocols and equipment. To date, there have been only 4 reported cases, and there is a need to conduct more studies for a better understanding of the mechanism of ankle ligamentous sprain injury.

PURPOSE

This study presents 5 cases in tennis and a comparison with 4 previous cases for a better understanding of the mechanism of ankle ligamentous sprain injury.

STUDY DESIGN

Case series; level of evidence, 4.

METHODS

Five sets of videos showing ankle sprain injuries in televised tennis competition with 2 camera views were collected. The videos were transformed, synchronized, and rendered to a 3-dimensional animation software. The dimensions of the tennis court in each case were obtained to build a virtual environment, and a skeleton model scaled to the injured athlete's height was used for the skeleton matching. Foot strike was determined visually, and the profiles of the ankle joint kinematics were individually presented.

RESULTS

There was a pattern of sudden inversion and internal rotation at the ankle joint, with the peak values ranging from 48°-126° and 35°-99°, respectively. In the sagittal plane, the ankle joint fluctuated between plantar flexion and dorsiflexion within the first 0.50 seconds after foot strike. The peak inversion velocity ranged from 509 to 1488 deg/sec.

CONCLUSION

Internal rotation at the ankle joint could be one of the causes of ankle inversion sprain injury, with a slightly inverted ankle joint orientation at landing as the inciting event. To prevent the foot from rolling over the edge to cause a sprain injury, tennis players who do lots of sideward cutting motions should try to land with a neutral ankle orientation and keep the center of pressure from shifting laterally.

Laparoscopic sacrocolpopexy for uterine and post-hysterectomy prolapse: anatomical and functional outcomes

OBJECTIVE

To evaluate the anatomical and functional outcomes following laparoscopic sacrocolpopexy in a local unit.

DESIGN

Retrospective case series.

SETTING

A regional hospital in Hong Kong.

PATIENTS

All women who underwent laparoscopic sacrocolpopexy for symptomatic uterine or post-hysterectomy prolapse from January 2003 to December 2008.

MAIN OUTCOME MEASURES

Anatomical outcomes, functional outcomes including complications.

RESULTS

A total of 31 patients were recruited. The success rate in treating apical vaginal wall prolapse was 100%. There were no recurrences of vault prolapse (defined as stage II or higher). Approximately 19% of women had anterior vaginal wall prolapse and 23% had urinary stress incontinence postoperatively; 6% had a second operation because of anterior vaginal wall prolapse. The rates of dyspareunia and constipation were low. The mean hospital stay was 4 (range, 2-11) days. Two patients sustained bladder injuries and one rectal injury resulting in a rectovaginal fistula. For three patients the procedure was converted to a laparotomy.

CONCLUSIONS

Laparoscopic sacrocolpopexy is feasible in our population and has a high success rate for treating apical vaginal wall prolapse. The incidence of complications was acceptable.

An ankle joint model-based image-matching motion analysis technique

This study presented a model-based image-matching (MBIM) motion analysis technique for ankle joint kinematic measurement. Five cadaveric below-hip specimens were manipulated through a full range of ankle joint motions in bare-foot and shoed conditions. The ankle motions were analyzed by bone-pin marker-based motion analysis and MBIM motion analysis techniques respectively. The root mean square errors of all angles of motion were less than 3°. The average Intraclass Correlation Coefficients (ICCs) for the intra-rater reliability were greater than 0.928 and the average ICCs for the inter-rater reliability were greater than 0.948 for all angles of motion. Excellent validity, intra-rater reliability and inter-rater reliability were achieved for the MBIM technique in both bare-foot and shoed conditions. The MBIM technique can therefore provide good estimates of ankle joint kinematics.

Understanding acute ankle ligamentous sprain injury in sports

This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing – a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60–90 ms). The failure supination or inversion torque is about 41–45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not be used as it results in joint stiffness, muscle atrophy and loss of proprioception. Traditional Chinese medicine such as herbs, massage and acupuncture were well applied in China in managing sports injuries, and was reported to be effective in relieving pain, reducing swelling and edema, and restoring normal ankle function. Finally, the best practice of sports medicine would be to prevent the injury. Different previous approaches, including designing prophylactice devices, introducing functional interventions, as well as change of games rules were highlighted. This paper allows the readers to catch up with the previous researches on ankle sprain injury, and facilitate the future research idea on sport-related ankle sprain injury.

Effects of meteorological conditions on PM10 concentrations--a study in Macau

Review on the annual PM10 concentrations over a 10-year period shows that Macau is subjected to severe fine particulate pollution. Investigations of its variation in monthly and daily time scales with the local meteorological records reveal further details. It is found that a distinct feature of the Asian monsoon climates, the changes of wind direction, mainly controls the general trend of PM10 concentration in a year. The monsoon driven winter north-easterly winds bring upon Macau dry and particle enriched air masses leading to a higher concentration in that period while the summer south-westerly winds transport humid and cleaner air to the region leading to a lower PM10 value. This distinct seasonal feature is further enhanced by the lower rainfall volume and frequency as well as mixing height in winter and their higher counterparts in summer. It is also found that the development of tropical cyclones near Macau could also impose episode like PM10 concentration spikes due to the pre-typhoon induced stagnant air motion followed by the swing of wind direction to the northerly.