A cross-sectional analysis of sagittal knee laxity and isokinetic muscle strength in soccer players

In this cross-sectional study, sagittal knee laxity and isokinetic strength of knee extensor and flexor muscle groups were measured and differences related to leg dominance were evaluated. A total of 44 healthy male soccer players (who had trained regularly at least for the last five years) and 44 sedentary people as their control counterparts were involved in this study. All participants were tested using a KT-1000 knee arthrometer for knee laxity. Isokinetic concentric knee peak torque and hamstring/quadriceps (H/Q) ratio were also measured at 60, 180, 300 degrees/s through a Cybex 2 - 340 dynamometer. Posterior laxity in the non-dominant side of soccer players was significantly higher than in the dominant side (p < 0.005) while there were no significant anterior and total anteroposterior (total AP) laxity differences in both groups. Soccer players had significantly lower anterior and total AP laxity values than controls (p < 0.0001) while there was no significant difference between posterior laxity values in both sides. Dominant extremity demonstrated significantly higher knee flexor peak torque and H/Q ratio at 180 degrees /s in soccer players (p < 0.05). Similarly in sedentary controls, H/Q ratio at 60 degrees /s of the dominant side was significantly higher than that in the non-dominant side (p < 0.05). Soccer players had significantly higher extensor and flexor peak torque values and H/Q ratios than sedentary subjects for both extremities. In both groups, there were no significant correlations between knee laxity and isokinetic knee extensor and flexor strength and H/Q ratios except weak negative correlation between posterior knee laxity and isokinetic extensor peak torque at 60, 180 and 300 degrees /s (p < 0.005, r = - 0.43, p < 0.05, r = - 0.39, p < 0.05, r = - 0.32 respectively) in the non-dominant side of soccer players and at 300 degrees /s (p < 0.05, r = - 0.32) in the non-dominant side of controls. Soccer players demonstrated significantly less sagittal knee laxity and higher isokinetic strength of the knee flexors and extensors compared to sedentary controls. Isokinetic strength difference was found to be higher for the flexor muscle group. Further prospective studies are needed to explain whether the increased H/Q ratio decreases the risk of ligamentous injury.     

Isokinetic strength testing in patients with chronic heart failure--a reliability study

Measurement of skeletal muscle strength gains increasing importance as outcome parameter in patients with chronic heart failure. This study aimed at establishing short-term reliability of isokinetic strength measurements of knee extensor and flexor muscles in 38 patients with chronic heart failure. Strength tests were performed on the Cybex 6000 dynamometer. Trunk fixation was restricted to pelvic fixation. Two bouts of strength testing were performed on day 1 and one on day 5. Each isokinetic bout consisted of 3 reciprocal knee extension and flexion movements with an angular speed of 60 degrees per second. Isometric strength was measured at 30 degree knee angulation. Intraclass correlations ranged between 0.96 and 0.99 for isokinetic and isometric peak torque of knee extensor muscles and 0.82-0.96 for flexor muscles. Analysis of repeated measurements showed significant differences among the values of flexor peak torque in the isokinetic mode and between all measurements in the isometric mode (p < 0.05). Pearson's correlation coefficients for isokinetic and isometric extensor peak torques ranged between 0.95 and 0.99, for flexor peak torques between 0.81 and 0.85 (all p < 0.0001). Measurement of isokinetic knee extensor and flexor peak torque is a reliable method to assess muscle strength in patients with chronic heart failure even with altered trunk fixation.     

Lower-extremity isokinetic strength ratios of elite springboard and platform diving athletes

Objectives: The purpose of the present study was to examine knee extensor and flexor muscle strength ratios of an elite group of diving athletes.

Methods: Sixteen divers (10 females and 6 males) from the Brazil national team were assessed for lower-body strength. They had participated in international competitions such as the 2016 Olympic Games and 2015 Pan American Games. The dynamic concentric torque of their knee flexor and extensor muscles were evaluated using a Biodex isokinetic dynamometer. Bilateral tests were performed at 60º s^?1. Flexor to extensor (F/E) peak torque ratio and percentage bilateral difference (BD%) was also measured.

Results: The results revealed that elite diving athletes produced higher than usual reported in previous studies for relative knee extension torque (3.2 for females and 3.6 for males N?m?kg^?1). However, they presented low levels of knee flexor torque (1.5 for females and 1.8 for males N?m?kg^?1). These results are reflected in a low F/E ratio (0.39 to 0.49). Males presented a greater BD% in knee flexors when compared to females (12.4% vs 6.6%).

Conclusion: Elite diving athletes demonstrated high knee extensor and low knee flexor strength. This partially explains their low F/E ratio, which might increase risk of knee injuries. Strength and conditioning programs should strive to correct knee strength imbalances in diving athletes where necessary.     

Isokinetic investigation of knee extensors and knee flexors in young French soccer players

The knee extensor and knee flexor muscle groups in three groups of young soccer players were tested with a Cybex II isokinetic dynamometer and compared with adults. Muscle strength increased with age. The largest gain was observed in young players aged 16-17 years whose quadriceps was the most modified muscle group giving the lowest H/Q ratio. Analysis of the regression equations obtained for torque values at 30 degrees s-1 and 180 degrees s-1 revealed that there were two distinct groups: under 16 and over 16. After reaching 16 years of age, the increase in muscle strength is greater at low velocity than at high velocity.     

Knee strength deficits after hamstring tendon and patellar tendon anterior cruciate ligament reconstruction

PURPOSE: The purpose of this study was to examine the strength of the knee flexors and knee extensors after two surgical techniques of ACL reconstruction and compare them to an age and activity level matched control group. METHODS: Twenty-four subjects who had undergone ACL reconstruction greater than 1 yr previously were placed into one of two groups according to autograft donor site: patellar tendon (BPB; N = 8) and hamstring (H; N = 16), and compared with an active, control group (N = 30). Knee flexor and extensor strength was evaluated using isovelocity dynamometry (5 speeds, eccentric and concentric, 5-95 degrees ROM). Strength maps were used to graphically analyze strength over a broad operational domain of the neuromuscular system. Average strength maps were determined for each autograft group and compared with controls. A difference map (control minus graft group) and confidence (t-test) maps were used to quantitatively identify strength deficits. RESULTS: The combined ACL group (N = 24) revealed a global 25.5% extensor strength deficit, with eccentric regional (angle and velocity matched) deficits up to 50% of control. Strength deficits covered over 86% of the sampled strength map area (P < 0.01). These knee extensor strength deficits are greater than previously reported. In addition, the BPB group demonstrated a concentric, low velocity, knee extensor strength deficit at 60-95 degrees that was not observed in the H group. Significant graft site dependent, regional knee flexor deficits of up to 50% of control were observed for the H group. CONCLUSIONS: Strength deficits localized to specific contraction types and ranges of motion were demonstrated between the ACL and control groups that were dependent upon autograft donor site. Postoperative rehabilitation protocols specific to these deficits should be devised.     

Knee isokinetic muscle strength and balance ratio in female soccer players of different age groups: a cross-sectional study

ABSTRACT

Background: As a consequence of years of soccer training and sexual maturation, there is an increase in lower body muscle mass and strength especially in the knee extensors and flexors muscles. In this context, the lack of knee joint stability, resulting from strength imbalance between knee extensor and flexors muscles, has been associated with knee injuries. The aim of this study was to compare the knee flexor and extensor muscle peak torque, average power, contralateral deficit, conventional and functional balance ratios of female soccer players from different age groups.

Methods: Sixty-six female soccer players were divided into four groups: under 13 (U13), under 15 (U15), under 17 (U17) years old and professional (PRO). Flexor and extensor knee muscle strength in concentric and eccentric actions of both limbs were assessed using isokinetic dynamometer.

Results: For the dominant limb, the knee concentric extensor muscles peak torques, assessed at 60 and at 240 deg/sec, and the average power of U15 group were significantly higher than U13 group. Extensor muscle average power of the PRO group was higher than U17. Dominant knee flexor average power of U15 was significantly higher than the U13 group. Peak torque at 60 deg/sec and 240 deg/sec and average power of the PRO group were higher than the U17 group. No differences were found regarding the eccentric action for flexor and extensor muscles. Conventional and functional balance ratios were similar among all age group, except for U13, which presented higher values than the U15 group for the dominant limb.

Conclusions: The greatest improvement in muscular performance occur when the athlete starts practicing soccer (after U13) and when they become professional (after U17) and the balance ratios, and muscle balance ratios remain stable in all age groups, although they are below the recommended level in the literature, which may increase the risk for lower limb injury.     

Delayed gastrocnemius muscle response to sudden perturbation in rehabilitated patients with anterior cruciate ligament reconstruction

This nonrandomized, posttest-only comparison between two experimental groups and a control group compared the lower extremity muscle activation latencies of patients following rehabilitated unilateral anterior cruciate ligament (ACL) reconstruction (allograft or autograft bone-patellar tendon-bone tissue) and normal control subjects. Twenty-three subjects (seven allograft, eight autograft, eight normal control) of similar age, height, weight, isokinetic knee extensor, and flexor peak torque/bodyweight, functional capability (single leg broad jump and single leg vertical jump) and recreational activity level participated in this study. Experimental group subjects were 21.3+/-5 months (allograft) and 27.6+/-10 months (autograft) after surgery. Kinematic and electromyographic data were sampled during ten randomly timed unilateral perturbations. Experimental group gastrocnemius latencies were delayed (allograft 59.5+/-25 ms, autograft 69+/-20 ms) compared to the control group (31.8+/-11 ms). The allograft (r=0.80) and autograft (r=0.40) unilateral ACL reconstruction groups displayed moderate and weak positive relationships between anterior knee laxity and knee angular displacements following perturbation, respectively. Control group subjects did not display significant relationships between these variables (r=-0.07). In the allograft group there was also a moderate inverse relationship between gastrocnemius latency and knee angular displacement following perturbation (r=-72). The autograft (r=-0.06) and control (r=-0.21) groups did not show similar relationships between these variables. Delayed gastrocnemius latencies for the experimental groups suggested prolonged neuromuscular deficits during weight-bearing dynamic knee stabilization. Knee angular displacement magnitude following sudden perturbation was related more strongly to knee laxity and gastrocnemius latency among subjects who had undergone ACL reconstruction using allograft bone-patellar tendon-bone tissue.     

优秀击剑运动员下肢三关节等速肌力测试分析

目的:研究我国优秀击剑运动员下肢髋、膝、踝三关节肌群等速肌力表现,找出薄弱肌群。方法:国家击剑队备战2008年奥运会重点队员26名,男女各13名,年龄23.1±2.36岁。在60°/s、240°/s速度下测定运动员双侧下肢髋、膝、踝屈伸肌群等速向心峰力矩。结果发现:(1)髋关节:在240°/s下双侧伸肌峰力矩均明显低于60°/s(P<0.05),60°/s和240°/s下双侧髋关节屈肌峰力矩无显著差异(P>0.05);男运动员两个速度下前腿伸肌峰力矩均显著高于后腿(P<0.05),女运动员无显著差异(P>0.05);两个速度下,运动员双腿屈伸肌峰力矩比值低于正常。(2)膝关节:60°/s时男运动员双腿屈伸肌峰力矩有显著差异(P<0.05),240°/s时双侧伸肌峰力矩有显著差异(P<0.05),女运动员两个速度下均无显著差异(P>0.05);60°/s时,女运动员前后腿屈伸肌峰力矩比值分别为0.56和0.54,男运动员分别为0.63和0.67;240/°s时男女前后腿屈伸肌峰力矩比值均在正常范围。(3)踝关节:60°/s时男运动员前腿踝关节屈伸肌峰力矩显著大于后腿(P<0.05),240°/s时无显著差异(P>0.05);两个速度下,女运动员踝关节屈伸肌峰力矩均无显著性差异(P>0.05);运动员踝关节屈伸峰力矩比值在两个速度下均低于正常。结论:优秀男子击剑运动员下肢关节等速肌力双侧不对称,女运动员不对称表现不明显;击剑运动员下肢薄弱肌群为后腿髋关节伸肌群、股后肌群、前腿股后肌群及踝关节背伸肌群。     

机械性踝关节不稳患者踝屈、伸肌群等速肌力评价

目的:评价机械性踝关节不稳(mechanical ankle instability,MAI)患者踝屈、伸肌群的等速肌力。方法:20名单侧机械性踝关节不稳患者的双侧踝关节分别接受等速肌力测试(60°/s和120°/s)。比较患侧和健侧踝关节屈、伸肌群相对峰力矩、平均功率、总功和屈伸力矩比的差异。结果:60°/s时,两侧伸肌群相对峰力矩、平均功率及总功的差别均无统计学意义(P=0.303,P=0.548,P=0.452),屈肌群相对峰力矩、平均功率和屈伸力矩比均无显著性差异(P=0.417,P=0.275,P=0.870),但屈肌群总功有显著性差异(P=0.043)。120°/s时,两侧伸肌群相对峰力矩、平均功率及总功差别均无统计学意义(P=0.096,P=0.069,P=0.233),但屈肌群相对峰力矩、平均功率、总功和屈伸力矩比有显著性差异(P=0.030,P=0.043,P=0.017,P=0.036)。结论:机械性踝关节不稳患者患侧踝关节跖屈肌群快速运动时肌力下降,这可能与其踝关节稳定性有关。     

The muscle strength and bone density relationship in young women: dependence on exercise status

AIM: Numerous studies report an association between muscle strength and bone mineral density (BMD) in young and older women. However, the participants are generally non-athletes, thus it is unclear if the relationship varies by exercise status. Therefore, the purpose was to examine the relationships between BMD and muscle strength in young women with markedly different exercise levels. METHODS: Experimental design: cross-sectional. Setting: a University research laboratory. Participants: 18 collegiate gymnasts and 22 age- and weight-matched recreationally active control women. Measures: lumbar spine, femoral neck, arm, leg and whole body BMD (g/cm(2)) were assessed by dual X-ray absorptiometry. In addition, lumbar spine and femoral neck bone mineral apparent density (BMAD, g/cm(3)) was calculated. Handgrip strength and knee extensor and flexor torque (60 degrees /s) were determined by dynamometry, and bench press and leg press strength (1-RM) using isotonic equipment. RESULTS: BMD at all sites and bench press, leg press and knee flexor strength were greater in gymnasts than controls (p<0.001). In controls, knee extensor torque was significantly correlated to femoral neck, limb and whole body BMD (r=0.47-0.55, p<0.05), leg press strength was associated with limb and whole body BMD (r=0.52-0.74, p<0.05), and bench press strength with arm BMD (r=0.50, p=0.019). In partial correlations controlling for weight, leg press strength was related to leg and whole body BMD (r=0.46-0.63, p<0.05). There was no association between muscle strength and BMD in gymnasts. CONCLUSION: These results suggest that the association between muscle strength and BMD in young women is dependent on exercise status. The osteogenic effect of increased mechanical loading associated with gymnastics training likely contributes to the dissociation of the relationship in gymnasts.     

Effect of surgical closing in total knee arthroplasty at flexion or extension: a prospective,randomized study

Purpose

The aim of this study was to evaluate the effect of knee position during wound closure (flexed vs. extended) in total knee arthroplasty on knee strength and function, as determined by knee society scores and isokinetic testing of extensor and flexor muscle groups.

Methods

In a prospective, randomized, double-blind trial, 29 patients were divided in two groups: for Group 1 patients, surgical closing was performed with the knee extended, and for Group 2 patients, the knee flexed at 90°. All the patients were treated with the same anaesthesia method, surgical team, surgical technique, prosthesis type, and rehabilitation process. American Knee Society Score values and knee flexion degrees were recorded. Isokinetic muscle strength measurements of both knees in flexion and extension were taken using 60° and 180°/s angular velocity. The peak torque and total work values, isokinetic muscle strength differences, and total work difference values were calculated for surgically repaired and healthy knees.

Results

No significant difference in the mean American Knee Society Score values and knee flexion degrees was observed between the two groups. However, using isokinetic evaluation, a significant difference was found in the isokinetic muscle strength differences and total work difference of the flexor muscle between the two groups when patients were tested at 180°/s. Less loss of strength was detected in the isokinetic muscle strength differences of the flexor muscle in Group 2 (?4.2 %) than in Group 1 (?23.1 %).

Conclusion

For patients undergoing total knee arthroplasty, post-operative flexor muscle strength is improved if the knee is flexed during wound closure.

Level of evidence

II.     

Tibiofemoral kinematics following successful anterior cruciate ligament reconstruction using dynamic multiple resonance imaging

BACKGROUND: The aim of anterior cruciate ligament reconstruction is to reduce excess joint laxity, hoping to restore normal tibiofemoral kinematics and therefore improve joint stability. It remains unclear if successful ACL reconstruction restores normal tibiofemoral kinematics and whether it is this that is associated with a good result. STUDY: Case series. PURPOSE: To assess the kinematics of the anterior cruciate ligament-reconstructed knee using open-access MRI. METHODS: Tibiofemoral motion was assessed using open-access MRI, weightbearing through the arc of flexion from 0 degrees to 90 degrees in 10 patients with isolated reconstruction of the anterior cruciate ligament (hamstring autograft) in one knee and a normal contralateral knee. Midmedial and midlateral sagittal images were analyzed in all positions of flexion in both knees to assess the tibiofemoral relationship. Sagittal laxity was also assessed by performing the Lachman test while the knees were scanned dynamically using open-access MRI. RESULTS: The amount of excursion between the tibial and femoral joint surfaces was similar between the normal and reconstructed knees, but the relationship of tibia to femur was always different for each position of knee flexion assessed-the lateral tibia being about 5 mm more anterior in the anterior cruciate ligament-reconstructed knees. This anterior tibial position is statistically significantly different at 0 degrees (P <.0006), 20 degrees (P =.0004), 45 degrees (P =.002), and 90 degrees of flexion (P <.006). Anteroposterior laxity was similar between normal and anterior cruciate ligament-reconstructed knees. CONCLUSION: Anterior cruciate ligament reconstruction reduces sagittal laxity to within normal limits but does not restore normal tibiofemoral kinematics despite a successful outcome.     

Comprehensive isokinetic knee measurements and quadriceps tendon evaluations in footballers for assessing functional performance

OBJECTIVES: To ascertain whether detailed isokinetic knee muscle testing reflects the results of other functional measurements in footballers and to look for any correlations between quadriceps tendon thickness and knee strength. METHODS: Ultrasonographic evaluation of the quadriceps tendon (Hitachi EUB-405), isokinetic knee testing (Biodex System 3), and sprint measurements using telemetric photoelectric cells (Chronometre Prosport ESC TX02) were carried out on 29 elite footballers. Jumping capacity was evaluated using Bosco's jumping mat (Ergojump). Anaerobic fitness was assessed by auricular capillary blood lactate measurements (YSI Model 1500 Sport Lactate Analyzer). RESULTS: Quadriceps tendon thickness correlated positively with jumping and sprint measurements and negatively with extensor and flexor strength. However, these correlations did not reach statistical significance. There were significant correlations between knee extensor strength at 60 degrees /s and jumping or sprint measurements and between the extension acceleration values of both knees during isokinetic tests at 240 degrees /s and the sprint measurements. No significant correlation was found between the fatigue ratio values of both knees at 240 degrees /s and the calculated fatigue ratios from the sprint measurements. CONCLUSIONS: Apart from a few variables which correlated with the performance tests, the isokinetic studies did not fully predict the various functional measurements. Neither was there any relation between the quadriceps tendon measurements and the knee strength values nor with the functional performance.     

中国女子篮球运动员膝关节等速肌力测试分析

目的:了解中国国家女子篮球队运动员膝关节等速肌力特征。方法:选用IsoMed 2000等速测试系统,采用60°/s、180°/s、240°/s三种角速度,测试18名中国女篮国家队运动员膝关节等速肌力。根据场上位置将运动员分为三组:后卫组7人(1、2号位),前锋组6人(3、4号位),中锋组5人(5号位),比较分析三组运动员的测试结果。结果:(1)女篮运动员双侧膝关节慢速测试时(60°/s)屈伸肌峰力矩(PT)显著高于快速测试(180°/s,240°/s),膝关节屈伸肌峰力矩比值(H/Q)随测试速度增加递增,左右膝H/Q无显著性差异。(2)慢速测试时(60°/s),左右膝关节峰力矩、峰力矩/体重比值、平均功率、H/Q无显著差异。(3)快速测试(240°/s)时,左膝屈肌PT、峰力矩/体重比值(PT/BW)显著高于右膝。180°/s测试时,左膝屈肌平均功率显著高于右膝。(4)60°/s测试时,后卫、前锋、中锋运动员PT、PT/BW组间比较无显著性差别。180°/s测试时,后卫运动员左膝屈肌PT与前锋、中锋运动员比较有显著性差异(P=0.02),各组间伸肌PT未见显著差异。240°/s测试时,后卫运动员右膝屈、伸肌PT/BW和中锋运动员比较均存在显著差异;后卫、前锋、中锋三组运动员平均功率、H/Q、总功与峰值功率组间比较均无显著性差别。结论:(1)女篮运动员快速测试(240°/s)时左膝屈肌力量强于右膝,反映快速运动时左右膝关节肌力不平衡。(2)不同场上位置女篮运动员膝关节等速肌力快速测试结果有差异性,提示力量训练应根据场上位置进行特异性训练。(3)女篮运动员需加强屈肌快速力量训练,以提高H/Q,预防膝关节损伤。     

Isokinetic strength and anaerobic power of elite, subelite and amateur French soccer players

Information about the influence of different practice levels on physical characteristics of a large number of soccer players is lacking. Therefore we assessed muscular strength and anaerobic power of elite, subelite and amateur soccer players to clarify what parameters distinguish the top players from the less successful. We tested 95 soccer players from the French first division (elite), second division (subelite), and amateurs and determined the isokinetic strength of the knee extensor and flexor muscles at angular velocities from -120 degrees x s(-1) to 300 degrees x s(-1). Vertical jump, 10 m sprint, 30 m sprint and maximum ball speed during shooting were also measured. The elite players had higher knee flexor torque than the amateurs at all angular velocities (p < 0.05), except at 300 degrees x s(-1). The hamstring/quadriceps ratios proposed with two different methods were significantly lower in the amateur group than in the elite group (p < 0.05), except at 300 degrees x s(-1). Maximum ball speed during shooting and speed over 30 m sprint were not different between elite, subelite, and amateur players while speed over a 10 m sprint was significantly slower in amateur players and faster in the elite group (p < 0.05). Although performance in soccer is not determined only by measurable variables, professional players differ from amateurs in terms of knee flexor muscle strength and short-distance sprinting speed. Based on these findings we conclude that hamstring strength is extremely important in soccer players for joint stabilization during various tasks, notably in eccentric action. Further, short-sprinting performance may mirror actual game situations at high level and could be an important determinant of match-winning actions.     

Knee joint laxity and neuromuscular characteristics of male and female soccer and basketball players.

Anterior cruciate ligament injuries are occurring at a higher rate in female athletes compared with their male counterparts. Research in the area of anterior cruciate ligament injury has increasingly focused on the role of joint proprioception and muscle activity in promoting knee joint stability. We measured knee joint laxity, joint kinesthesia, lower extremity balance, the amount of time required to generate peak torque of the knee flexor and extensor musculature, and electromyographically assessed muscle activity in 34 healthy, collegiate-level athletes (average age, 19.6 +/- 1.5 years) who played soccer or basketball or both. Independent t-tests were used to determine significant sex differences. Results revealed that women inherently possess significantly greater knee joint laxity values, demonstrate a significantly longer time to detect the knee joint motion moving into extension, possess significantly superior single-legged balance ability, and produce significantly greater electromyographic peak amplitude and area of the lateral hamstring muscle subsequent to landing a jump. The excessive joint laxity of women appears to contribute to diminished joint proprioception, rendering the knee less sensitive to potentially damaging forces and possibly at risk for injury. Unable to rely on ligamentous structures, healthy female athletes appear to have adopted compensatory mechanisms of increased hamstring activity to achieve functional joint stabilization.     

Preseason strength and flexibility imbalances associated with athletic injuries in female collegiate athletes

One hundred thirty-eight female collegiate athletes, participating in eight weightbearing varsity sports, were administered preseason strength and flexibility tests and followed for injuries during their sports seasons. Strength was measured as the maximal isokinetic torque of the right and left knee flexors and knee extensors at 30 and 180 deg/sec. Flexibility was measured as the active range of motion of several lower body joints. An athletic trainer evaluated and recorded injuries occurring to the athletes in practice or competition. Forty percent of the women suffered one or more injuries. Athletes experienced more lower extremity injuries if they had: 1) a right knee flexor 15% stronger than the left knee flexor at 180 deg/sec; 2) a right hip extensor 15% more flexible than the left hip extensor; 3) a knee flexor/knee extensor ratio of less than 0.75 at 180 deg/sec. There was a trend for higher injury rates to be associated with knee flexor or hip extensor imbalances of 15% or more on either side of the body. These data demonstrate that specific strength and flexibility imbalances are associated with lower extremity injuries in female collegiate athletes.     

Patellar and hamstring autografts are associated with different jump task loading asymmetries after ACL reconstruction

After anterior cruciate ligament reconstruction (ACLR), there is a higher re‐injury rate to the contralateral limb in athletes who undergo surgery using a bone‐patellar‐tendon‐bone (BPTB) autograft than using a semitendinosus and gracilis hamstring tendon (HT) autograft. This may be influenced by differing lower‐limb loading asymmetries present when athletes of each graft type return to play (RTP). The aim of this study was to compare bilateral countermovement jump (CMJ) phase‐specific impulse asymmetries between athletes with BPTB and HT autografts 9 months post‐ACLR, and to identify the relationship between impulse and isokinetic strength asymmetries. Male field sport athletes with a BPTB (n = 22) or HT (n = 22) autograft were tested approximately 9 months post‐ACLR. An uninjured control group (n = 22) was also tested on a single occasion. Phase‐specific bilateral absolute impulse asymmetries were calculated during the CMJ and compared between groups using Kruskal‐Wallis and post‐hoc testing. A linear regression model was used to assess the relationship between impulse asymmetries and isokinetic concentric knee extensor strength asymmetries. BPTB athletes demonstrated greater impulse asymmetries than HT athletes during the eccentric (P = 0.01) and concentric (P = 0.008) phases of the jump. Isokinetic strength asymmetry was a significant predictor of CMJ concentric impulse asymmetry in both BPTB (r² = 0.39) and HT athletes (r² = 0.18) but not eccentric impulse asymmetry in any group. The greater loading asymmetries demonstrated by BPTB than HT athletes 9 months after ACLR may contribute to the differing incidence rates of contralateral ACL injury. The findings suggest that graft‐specific loading asymmetries should be targeted during rehabilitation prior to RTP.     

Knee laxity measurements after anterior cruciate ligament reconstruction, using either bone–patellar–tendon–bone or hamstring tendon autografts, with special emphasis on comparison over time

The aims of the study were to analyse the change in knee laxity over time after anterior cruciate ligament (ACL) reconstruction, using either bone–patellar–tendon–bone (BPTB) or hamstring (HS) tendon autografts, and to compare the knee laxity measurements between the study groups both pre-operatively and on multiple follow-up occasions. Another aim was to compare the radiographic findings in terms of degenerative changes between the study groups. A randomised series of 71 patients, who underwent ACL reconstruction using BPTB or HS tendon autografts and interference screw fixation, were included in the study. Of these patients, 47/71 (66%) attended a clinical examination, including laxity measurements using the KT-1000 arthrometer, pre-operatively and on four post-operative occasions; 6 months, 1 year, 2 years and 7 years after the reconstruction. The BPTB group consisted of 22 patients, while there were 25 patients in the HS group. There were no significant differences in the mean side-to-side knee laxity between the BPTB and the HS group pre-operatively or at the follow-up examinations. There was a tendency towards a reduction in side-to-side knee laxity over time in both groups, measured with the KT-1000 arthrometer. The decrease was significant when analysing the injured and uninjured knee separately (injured side p < 0.001 (BPTB) and p = 0.005 (HS), uninjured side p = 0.008 and p = 0.042, respectively). Forty-four patients (BPTB 21, ST 23) underwent a radiographic assessment at the 7-year follow-up, which revealed no significant differences between the study groups in terms of osteoarthritic findings classified according to the Fairbank and Ahlbäck rating systems. In overall terms, osteoarthritis was identified in 16% (BPTB 19%; ST 13%; n.s.) according to the Ahlbäck rating system and 68% (BPTB 67%; ST 70%; n.s.) according to the Fairbank rating system. There were no significant differences in knee laxity measurements between the two study groups pre-operatively or at 7 years. A decrease in knee laxity over time was seen in both groups. There were no significant differences between the BPTB and ST groups in terms of osteoarthritic findings at 7 years.     

Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon autograft: clinical outcome in 4–7 years

Surgical reconstruction of the anterior cruciate ligament (ACL) is indicated in the ACL-deficient knee with symptomatic instability and multiple ligaments injuries. In the present study, we describe the clinical results of quadriceps tendon-patellar bone autograft for ACL reconstruction. From 1996 to 1998, the graft has been used in 38 patients. Thirty-four patients with complete final follow-up for 4–7 years were analyzed. The average follow-up time was 62 (48–84) months. Thirty-two patients (94%) achieved good or excellent results by Lysholm knee rating. Twenty-six patients (76%) could return to moderate or strenuous activity after reconstruction. Twenty-eight patients (82%) had ligament laxity of less than 2 mm. Finally; 31 patients (91%) were assessed as normal or nearly normal rating by IKDC guideline. Twenty-five patients (73%) had less than 10 mm difference in thigh girth between their reconstructed and normal limbs. Thirty-two (94%) and 31 (91%) patients could achieve recovery of the extensor and flexor muscle strength in the reconstructed knee to 80% or more of normal knee strength, respectively. A statistically significant difference exists in thigh girth difference, extensor strength ratio, and flexor strength ratio before and after reconstruction. Tunnel expansion with more than 1 mm was identified in 2 (6%) tibial tunnels. Our study revealed satisfactory clinical subjective and objective results at 4–7 years follow-up. Quadriceps tendon autograft has the advantage of being self-available, relatively easier arthroscopic technique, and having a suitable size, making it an acceptable graft choice for ACL reconstruction. There is little quadriceps muscle strength loss after quadriceps harvest. A quadriceps tendon-patellar autograft is an adequate graft choice to ACL reconstruction.