Isokinetic quadriceps and hamstring muscle strength and knee function 5 years after anterior cruciate ligament reconstruction: comparison between bone-patellar tendon-bone and hamstring tendon autografts

Existing clinical studies have not proven which graft is to be preferred in anterior cruciate ligament (ACL) reconstruction. In recent years, bone-patellar tendon-bone and hamstring tendons have been the most frequently used graft types. Muscle strength deficit is one of the consequences after ACL reconstruction. The aim of this study was to evaluate possible differences in hamstring and quadriceps muscle strength and knee function 5 years after ACL reconstruction between the BPTB and the STG groups. The study group consisted of 288 patients (132 women, 156 men) with a unilateral ACL rupture who had received a BPTB (175 patients) or STG (113 patients) ACL reconstruction. Lower extremity concentric isokinetic peak extension and flexion torques were assessed at the angular velocities of 60°/s and 180°/s. The International Knee Documentation Committee (IKDC), the Tegner activity level, the Lysholm knee and the Kujala patellofemoral scores were also collected. Isokinetic quadriceps peak torque (percentage of the contralateral side) was 3.9% higher in the STG group than in the BPTB group at the velocity of 60°/s and 3.2% higher at the velocity of 180°/s and the isokinetic hamstring peak torque 2% higher in the BPTB group than in the STG group at the velocity of 60°/s and 2.5% higher at the velocity of 180°/s. In both groups the subjects had weaker quadriceps and hamstring muscle strength in the injured extremity compared with the uninjured one. In the single-leg hop test (according to the IKDC recommendations) there was a statistically significant difference (P = 0.040) between the groups. In the STG group, 68% of the patients had the single-leg hop ratio (injured vs. uninjured extremity) ≥90%, 31% of the patients 75–89% and 1% of the patients <75%, while in the BPTB group the corresponding percentages were 72, 21 and 7%. However, no statistically significant differences in clinical outcome were found between the groups as determined by the IKDC, Tegner activity level, Lysholm knee and Kujala patellofemoral scores.     

Joint position sense and rehabilitation in the anterior cruciate ligament deficient knee.

BACKGROUND: Impaired joint position sense (JPS) has been shown in anterior cruciate ligament (ACL) deficient and osteoarthritic knees. The relation between JPS and function is uncertain. The aim of this study was to determine further if ACL deficient knees show abnormal JPS and the effect of exercise therapy on JPS, and also to assess the relation between JPS, functional stability, and strength. METHODS: Fifty patients (46 men and four women, mean age 26.3 years) with unilateral ACL deficient knees were assessed on admission and after rehabilitation (5 hours a day for four weeks). JPS was assessed by reproduction of passive positioning using a visual analogue incorporating a goniometer. Knee stability was analysed by self report questionnaire (score 0-280) and functional activity test (single leg hop and figure of eight run). Isokinetic dynamometry was performed to evaluate quadriceps and hamstring peak torque strength. Controls were either age and sex matched individuals or the contralateral knee. Statistical analysis was by Wilcoxon signed rank test and Spearman rank order correlation coefficient. RESULTS: JPS was impaired in ACL deficient knees. The mean (SD) errors in reproducing angles were 9.4 (3.1) degrees and 7.1 (2.3) degrees for the ACL deficient knee and control knee respectively (P < 0.0005). There was no improvement in JPS after rehabilitation (9.4 (3.1) degrees and 8.5 (3.2) degrees before and after rehabilitation respectively, P = 0.14). There was improvement as ascertained from the questionnaire (on admission 202 (32.1), after rehabilitation 243 (25.4), P < 0.0001) and functional activity testing (hop: on admission 148.7 (37.3) cm, after rehabilitation 169.8 (31.1) cm, P < 0.0005; figure of eight: on admission 48.4 (16.6) seconds, after rehabilitation 41.6 (3.4) seconds, P < 0.0001). Quadriceps strength improved (peak torque on admission 198.5 (58.9) Nm, after rehabilitation 210.5 (54.2) Nm, P < 0.05), but not hamstring strength (peak torque on admission 130.6 (28.1) Nm, after rehabilitation 135.5 (27.7) Nm, P = 0.24). JPS did not correlate with the functional activity tests (hop and figure of eight run), the responses to the questionnaire, or strength. There was no correlation between the responses to the questionnaire and functional activity tests or muscle strength. CONCLUSIONS: JPS was impaired in ACL deficient knees. Although knee stability improved with exercise therapy, there was no improvement in JPS. The role of JPS in the stability of ACL deficient knees remains unclear.     

Knee flexor strength after ACL reconstruction: comparison between hamstring autograft, tibialis anterior allograft, and non-injured controls

Hamstring muscle group dysfunction following anterior cruciate ligament reconstruction (ACL) using a semitendinosus–gracilis autograft is a growing concern. This study compared the mean peak isometric knee flexor torque of the following three groups: subjects 2 years following ACL reconstruction using semitendinosus–gracilis autografts (Group 1), subjects 2 years following ACL reconstruction using tibialis anterior allografts (Group 2), and a non-injured, activity-level-matched control group (Group 3). We hypothesized that Group 1 would have greater mean involved lower extremity peak isometric knee flexor torque deficits than the other groups. Handheld dynamometry with subjects in prone and the test knee at 90° flexion was used to determine bilateral peak isometric knee flexor torque. Group 1 (86.4 ± 11) and Group 2 (80.5 ± 13) had similar 2000 IKDC Subjective Knee Evaluation Form scores (P = NS). Group 1 had a mean involved lower extremity peak isometric knee flexor torque deficit of −17.0 ± 14 Nm. Group 2 had a mean involved lower extremity peak isometric knee flexor torque deficit of −0.8 ± 9 Nm. Group 3 (control) had a mean left and right lower extremity peak isometric knee flexor torque difference of −0.7 ± 14 Nm. Group 1 had decreased involved lower extremity peak isometric knee flexor torque compared to Groups 2 and 3 (two-way ANOVA; group × side interaction P < 0.05, Tukey HSD = 0.008). Long-term knee flexor strength deficits exist following hamstring autograft use for ACL reconstruction that does not occur when a tibialis anterior allograft is used. Early identification of impaired knee flexor strength among this group and modified rehabilitation may reduce these deficits. Adding quantitative biomechanical testing of sprinting and sudden directional change movements to the standard physical therapy evaluation will better elucidate the clinical and functional significance of the observed knee flexor strength impairments and aid in determining sport specific activity training readiness.     

Knee extension and flexion muscle power after anterior cruciate ligament reconstruction with patellar tendon graft or hamstring tendons graft: a cross-sectional comparison 3 years post surgery

Hamstring muscles play a major role in knee-joint stabilization after anterior cruciate ligament (ACL) injury. Weakness of the knee extensors after ACL reconstruction with patellar tendon (PT) graft, and in the knee flexors after reconstruction with hamstring tendons (HT) graft has been observed up to 2 years post surgery, but not later. In these studies, isokinetic muscle torque was used. However, muscle power has been suggested to be a more sensitive and sport-specific measures of strength. The aim was to study quadriceps and hamstring muscle power in patients with ACL injury treated with surgical reconstruction with PT or HT grafts at a mean of 3 years after surgery. Twenty subjects with PT and 16 subjects with HT grafts (mean age at follow up 30 years, range 20–39, 25% women), who were all included in a prospective study and followed the same goal-based rehabilitation protocol for at least 4 months, were assessed with reliable, valid, and responsive tests of quadriceps and hamstring muscle power at 3 years (SD 0.9, range 2–5) after surgery. The mean difference between legs (injured minus uninjured), the hamstring to quadriceps (H:Q, hamstring divided by quadriceps) ratio, and the limb symmetry index (LSI, injured leg divided by uninjured and multiplied by 100) value, were used for comparisons between the groups (analysis of variance). The mean difference between the injured and uninjured legs was greater in the HT than in the PT group for knee flexion power (–21.3 vs. 7.7 W, p = 0.001). Patients with HT graft had lower H:Q ratio in the injured leg than the patients with PT graft (0.63 vs. 0.77, p = 0.012). They also had lower LSI for knee flexion power than those in the PT group (88 vs. 106%, p < 0.001). No differences were found between the groups for knee extension power. The lower hamstring muscle power, and the lower hamstring to quadriceps ratio in the HT graft group than in the PT graft group 3 years (range 2–5) after ACL reconstruction, reflect imbalance of knee muscles after reconstruction with HT graft that may have a negative effect on dynamic knee-joint stabilization.     

应用等速肌力测试评价膝前交叉韧带断裂重建术后康复的效果

目的:采用等速肌力测试系统测试前交叉韧带(ACL)断裂患者在重建术前、术后的肌肉力量,评价有、无严格的康复训练计划对患者康复效果的影响。方法:采用美国产Biodex System 3多关节等速肌力测试系统,以60°/s、120°/s两种速度测定67例膝关节前交叉韧带断裂及韧带重建术后6个月、12个月患者的股四头肌和腘绳肌肌力,包括峰力矩(PT)、峰力矩/体重比值(PT/BW)、总功(TW)、平均峰力矩(AVG PT)。将其中遵医嘱进行康复训练的24人作为康复训练组,另外无严格康复训练计划、自主活动的43人作为未康复训练组。结果:手术前患膝屈、伸肌群的PT、PT/BW、TW、AVG PT较健侧均显著降低;ACL重建术后6个月、12个月,两组患者股四头肌和腘绳肌肌力均较术前有所提高,其中未康复训练组患侧股四头肌肌力恢复至健侧70%左右,腘绳肌肌力恢复至健侧75%,康复训练组股四头肌和腘绳肌肌力分别恢复至健侧的80%和85%左右,高于未康复训练组,但与健侧相比仍有差距。结论:康复训练对ACL重建术后股四头肌和腘绳肌的肌力恢复有明显的作用。等速肌力测试是评价前交叉韧带重建术后康复效果的有效手段。     

Relationship between muscle volume and muscle torque of the hamstrings after anterior cruciate ligament lesion

Purpose

This study was conducted to identify factors other than morphological muscle strength factors that affect injured and uninjured sides of knee flexors with anterior cruciate ligament (ACL) lesions.

Methods

The study population consisted of 22 patients with ACL lesions. Their hamstring muscle volume was measured on MRI, and muscle torque per muscle volume was calculated as the peak torque of knee flexion divided by hamstring muscle volume.

Results

The mean muscle torque per unit volume of hamstrings in patients with ACL rupture was 0.09 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.01 Nm/cm³ at 180°/s on the injured side, and 0.11 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.01 Nm/cm³ at 180°/s on the uninjured side. The mean muscle torque per unit volume of hamstrings in control subjects was 0.11 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.03 Nm/cm³ at 180°/s. One-factor ANOVA analysis found no significant differences between the three groups at either flexion velocity.

Conclusions

Neurological dysfunction does not appear to exist in knee flexor muscles after ACL injury, unlike the quadriceps. Since the mechanism of muscle weakness will differ depending on the muscle, it is important for clinicians to take this discrepancy into consideration.

Level of evidence

II.     

A 2-year follow-up of rehabilitation after ACL reconstruction using patellar tendon or hamstring tendon grafts: a prospective randomised outcome study

Sixty-eight patients were clinically evaluated preoperatively, 3, 5, 7, 9 months, 1 and 2 years after ACL reconstruction, 34 with patellar tendon graft, 34 with hamstring graft. Outcome regarding graft choice and anterior knee laxity (P = 0.04) was in favour of patellar tendon graft. Hamstring graft led to a larger laxity, 2.4 mm compared with patellar tendon graft, 1.3 mm at 1 year and 2.5 mm and 1.5 mm, respectively, at 2 years (P = 0.05). There was a significant difference in rotational knee stability in favour of the patellar tendon graft at all test occasions but 9 months. A general effect regarding graft choice and muscle torque was found at 90°/s for quadriceps (P = 0.03) and hamstrings (P ≤ 0.0001) and at 230°/s for hamstrings (P ≤ 0.0001). No treatment effect regarding graft choice and one-leg hop test, postural sway or knee function was found. No group differences in anterior knee pain were found at any of the test occasions but 2 years in favour of hamstring graft compared to patellar tendon graft (P = 0.04). Patellar tendon graft resulted in higher activity level than hamstring graft at all test occasions but 1 year (P = 0.01). Patellar tendon ACL reconstruction led to more stable knees with less anterior knee laxity and less rotational instability than hamstring ACL reconstruction. Hamstring graft patients had not reached preoperative level in hamstring torque even 2 years after ACL reconstruction. Athletes with patellar tendon graft returned to sports earlier and at a higher level than those with hamstring graft.     

Short-term isokinetic and isometric strength outcomes after anterior cruciate ligament reconstruction in adolescents

ObjectivesTo examine differences in knee strength outcomes after ACL reconstruction according to quadriceps tendon (QT) or hamstring tendon (HT) autograft in adolescents.DesignRetrospective cohort.MethodsSurgical and clinical outcome data were collected. Analyses were conducted separately for female and male cohorts and grouped by graft type (HT or QT). A Mann-Whitney U test of independent samples was used to examine group differences according to graft type.Results107 females (age = 15.6 ± 1.5 years) and 94 males (age = 15.7 ± 1.5 years) were included. Mean time since surgery ranged from 7.2 to 7.9 months. Those with a QT autograft had decreased normalized isokinetic quadriceps peak torque on the involved limb compared to the HT group (p < 0.01, ES = 0.71–0.89). Normalized isometric hamstring peak torque was decreased for those with HT autograft in the female cohort (p = 0.02, ES = 0.57).ConclusionNormalized isokinetic quadriceps peak torque was reduced by 18–20% on the involved limb in those with a QT autograft. Normalized isometric hamstring peak torque was decreased by 13% for those with HT autograft in the female cohort. Method of strength testing may be an important consideration to fully appreciate strength deficits after ACL reconstruction according to graft type.     

Assessment of quadriceps/hamstring strength, knee ligament stability, functional and sports activity levels five years after anterior cruciate ligament reconstruction

The purpose of this study was to examine individuals 5 years after ACL reconstruction and analyze changes involving strength, stability, function, and sports activities. Nineteen males and six females, mean age = 31.4 +/- 7.31 years, participated in this study. Fifteen subjects had received extraarticular and ten subjects had received intraarticular ACL reconstructions. Subjects completed a 100 point subjective functional activity questionnaire and a sports participation survey. Knee ligament stability was assessed during an objective knee examination. Isokinetic quadriceps and hamstring muscle strength were tested at 240 and 120 deg/sec using the Cybex II dynamometer. Anterolateral rotatory instability and positive Lachman were elicited on the operated leg for 80% of the subjects. No significant relationship was found between objective instability and the functional activity score. For the intraarticular group, a significant correlation (P less than 0.05) was found between increased quadriceps and hamstring strength on the operated leg and return to functional activities. Subjects' functional activity score was positively correlated (P less than 0.001) with their ability to participate in sports. Subjects participating in sports involving cutting and twisting motions were less successful in returning to their preinjury participation levels and reported more subjective complaints of pain, swelling, and/or instability. These results indicate that long-term progressive rehabilitation emphasizing increased quadriceps and hamstring strength to approximate the nonoperated leg may enhance successful return to functional and sports activities after ACL reconstruction.     

Readiness for return to sport in non-surgically treated patients with anterior cruciate ligament injury following a public municipal rehabilitation program

ObjectivesTo investigate the proportion of patients that pass a return to sport (RTS) test battery and assess changes in patient-reported outcomes and lower extremity muscle strength following three months of exericse-based rehabilitation in non-surgically treated patients with anterior cruciate ligament (ACL) injury.DesignProspective cohort study.SettingClinical environment (public municipal).ParticipantsThirty-nine ACL injured patients (54% female, median age (IQR) 28 years (24–35).Main outcome measuresThe Knee Injury and Osteoarthritis Outcome Score, Knee Outcome Survey Activities of Daily Living Scale, single hop for distance, crossover hop for distance, side hop test, the Agility T-test, and quadriceps and hamstrings isometric maximal voluntary contraction (MVC).ResultsFollowing 3 months of rehabilitation, patients had statistically significant improvements in all patients-reported outcomes and in quadriceps and hamstring MVC. Of 28 patients who completed all RTS tests, 11% passed six RTS criteria, 14% five criteria, 11% four criteria, 4% three criteria, 18% two criteria, 21% one criterion, and 21% none of the criteria.ConclusionsThe results suggest that three months of public municipal rehabilitation improves patient-reported outcomes and lower extremity muscle strength in non-surgically treated patients with ACL injury. However, only one in every 10 patients passed all RTS criteria.     

The relationship between isokinetic quadriceps strength and laxity on gait analysis parameters in anterior cruciate ligament reconstructed knees

Gait alterations after ACL reconstruction have been reported in the literature. The current study examined a group of 14 patients who all had an ACL reconstruction with a patellar tendon autograft. Kinetic and kinematic data were obtained from the knee during walking. The flexion-extension deficit (FED) calculated from the angular difference between maximal flexion and maximal extension during the stance phase in the ACL-reconstructed and the normal knee was measured. We investigated whether these alterations in gait are related to quadriceps strength and residual laxity of the knee. It may be that patients modify their gait patterns to protect the knee from excessive anterior translation of the tibia by reducing the amount of extension during stance. On the other hand, persistent quadriceps weakness may also cause changes in gait patterns as the quadriceps is functioning as an important dynamic stabilizer of the knee during stance. Results showed that patients had a significantly higher FED value (4.9±4.0) than a healthy control group in a previous study (1.3±0.9). This is caused mainly by an extension deficit during midstance. External extension moments of the knee (T_ZMAX were significantly lower in the current patients group than in a healthy control group (T_ZMAX –0.27±0.19 Nm/kg in patients vs. –0.08±0.06 Nm/kg in controls). There were no significant correlations between quadriceps strength and gait analysis parameters. Furthermore no correlation was found between the amount of laxity of the knee and gait. The relevance of this study lies in the fact that apparently the measured gait alterations cannot be explained solely by often used biomechanical indicators such as laxity and strength. The measured gait alterations may be a result of the surgical procedure with subsequent modified motor programming.     

Fatigue after eccentric quadriceps femoris work produces earlier gastrocnemius and delayed quadriceps femoris activation during crossover cutting among normal athletic women

Athletic women are at greater risk of anterior cruciate ligament (ACL) injury than men. Twenty, healthy, athletic women were evaluated for the effect of preferred stance limb isokinetic quadriceps femoris and hamstring fatigue from eccentric work compared with controls on the activation onset of vastus medialis, rectus femoris, vastus lateralis, the medial hamstrings, biceps femoris, and gastrocnemius muscles. Following 3 weeks of crossover cut training, subjects were tested for fatigue effects (5 subjects/week, 3 conditions, 1 condition/day, order effect controlled) on muscle activation onsets prior to crossover cut landing heelstrike (mixed model, ANOVA, P < 0.05). Fatigue from eccentric quadriceps femoris work produced delayed vastus medialis (P = 0.03), rectus femoris (P = 0.007), and vastus lateralis (P = 0.03) activation onsets compared with control, but did not differ compared to hamstring fatigue. Neither hamstring nor quadriceps femoris fatigue produced differences (P > 0.05) in medial hamstring or biceps femoris activation onsets compared to control. Quadriceps femoris fatigue from eccentric work produced earlier gastrocnemius activation onsets (P = 0.048) than control, but did not differ for hamstring fatigue. The gastrocnemius appears to provide synergistic and compensatory dynamic knee stabilization in closed kinetic chain function during quadriceps femoris fatigue. This finding in a normal group at high risk of ACL injury while performing a maneuver with a high ACL injury risk supports gastrocnemius inclusion in knee rehabilitation and conditioning programs and suggests the need for comparative evaluations of knee injured/reconstructed subjects.     

Performance-based functional outcome for children 12 years or younger following anterior cruciate ligament injury: a two to nine-year follow-up study

There is limited scientific knowledge on ACL injuries in children 12 years or younger. Substantial controversy exists on treatment algorithms and there are no published data on performance-based functional outcome. Classification of adult ACL injured subjects as copers and non-copers is common, but no study has classified knee function in children using performance-based functional test after ACL injury. The aim of the present study was to evaluate the medium-term functional outcome among children with ACL injury and to classify them as copers and non-copers. Children 12 years or younger who were referred to our institution from 1996 to 2004 with an ACL injury were included. Twenty non-operated subjects (21 knees) and six ACL reconstructed subjects (7 knees) were examined at a minimum of 2 years after ACL injury or reconstruction. Four single-legged hop tests, isokinetic muscle strength measurements, and three functional questionnaires (IKDC 2000, KOS-ADLS and Lysholm) were used as outcome measurements. Children who had resumed their pre-injury activity level and performed above 90% on all hop tests were classified as copers following non-operative treatment and ACL reconstruction. The 26 children were on average 10.1 years at the time of injury. Of the non-operated children, 65% had returned to pre-injury activity level, and 50% were classified as copers. Copers scored significantly better than non-copers on single hop for distance, IKDC 2000, and Lysholm score. Of the non-operated children, 9.5% had suffered a secondary meniscus injury. Of the ACL reconstructed subjects, 67% were classified as copers at follow-up. Non-operated ACL-deficient children demonstrated excellent knee function on performance-based single-legged hop tests and 65% had returned to pre-injury activity level. Delayed ACL reconstruction resulted in success for a majority of the ACL-reconstructed children. Treatment algorithms for ACL-injured children are discussed.     

Comparison of anterior cruciate ligament reconstruction in male and female athletes using the patellar tendon and hamstring autografts

Despite the higher incidence of anterior cruciate ligament (ACL) injuries in female than in male athletes few authors have studied the effects of gender on the outcome of ACL reconstruction. This prospective study compared the results of ACL reconstruction using the patellar tendon and hamstring techniques in men and women. We prospectively followed 80 comparable athletes (46 males, 32 females) from a population of 287 patients operated on at our institution for ACL reconstruction using either patellar tendon or hamstring graft. There were 26 males and 14 females in the patellar tendon group, and 22 males and 18 females in the hamstring group. All patients were operated on by the same surgeon within 6 months from injury and underwent the same rehabilitation program at the same center. After an average of 36 months the patients were assessed by clinical evaluation, computerized knee laxity analysis, and isokinetic and functional strength tests; standard knee scores were also used. Among patellar tendon patients there were no significant differences between males and females regarding knee evaluation form, laxity, or isokinetic and functional tests. Females in the hamstring group had significantly greater laxity, and isokinetic tests at 1 year revealed a significantly higher deficit of peak torque at 60°/s in flexion and extension. We suggest further studies on the clinical significance of these findings particularly on their possible ramifications in the areas of return to sports and rehabilitation of female athletes     

Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study

Rehabilitation after anterior cruciate ligament (ACL) reconstruction has focused over the past decade on closed kinetic chain (CKC) exercises due to presumably less strain on the graft than with isokinetic open kinetic chain exercises (OKC); however, recent reports suggest that there are only minor differences in ACL strain values between some CKC and OKC exercises. We studied anterior knee laxity, thigh muscle torque, and return to preinjury sports level in 44 patients with unilateral ACL; group 1 carried out quadriceps strengthening only with CKC while group 2 trained with CKC plus OKC exercises starting from week 6 after surgery. Anterior knee laxity was determined with a KT-1000 arthrometer; isokinetic concentric and eccentric quadriceps and hamstring muscle torque were studied with a Kin-Com dynamometer before and 6 months after surgery. At an average of 31 months after surgery the patients answered a questionnaire regarding their current knee function and physical activity/sports to determine the extent and timing of their recovery. No significant differences in anterior knee laxity were noted between the groups 6 months postsurgery. Patients in group 2 increased their quadriceps torque significantly more than those in group 1, but no differences were found in hamstring torque between the groups. A significantly higher number of patients in group 2 (n=12) than in group 1 (n=5) returned to sports at the same level as before the injury (P<0.05). Patients from group 2 who returned to sports at the same level did so 2 months earlier than those in group 1. Thus the addition of OKC quadriceps training after ACL reconstruction results in a significantly better improvement in quadriceps torque without reducing knee joint stability at 6 months and also leads to a significantly higher number of athletes returning to their previous activity earlier and at the same level as before injury.     

Impaired voluntary quadriceps force control following anterior cruciate ligament reconstruction: relationship with knee function

Purpose

Impairments in quadriceps force control and altered quadriceps and hamstring muscle activation strategies have been observed following anterior cruciate ligament reconstruction; however, the functional implications of these impairments are unclear. This study examined the cross-sectional associations between quadriceps force control, quadriceps activation, hamstring coactivation and clinically assessed knee function following anterior cruciate ligament reconstruction with a hamstring graft.

Methods

Sixty-six patients (18 ± 3 months following surgery) and 41 uninjured individuals participated. Quadriceps force control was assessed using an isometric knee extension task. Participants cyclically increased and decreased quadriceps force at slow speeds between 5 and 30 % maximum voluntary isometric contraction matching a moving target displayed on a screen. Quadriceps activation and hamstring coactivation were assessed concurrently using surface electromyography. Knee function was assessed with the Cincinnati Knee Rating Scale and three single-leg hop tests.

Results

The reconstructed group completed the task with 48 % greater root-mean-square error (RMSE), indicating significantly worse quadriceps force control (p < 0.001). In a multivariable model adjusted for sex, greater RMSE and greater lateral hamstring coactivation were significantly associated with worse knee function that is greater odds of scoring <85 % on one or more knee functional assessment.

Conclusions

Less-accurate quadriceps force output and greater hamstring coactivation are associated with worse knee joint function following anterior cruciate ligament reconstruction and may contribute to irregular knee joint loading and the onset or progression of knee osteoarthritis. Impairments in quadriceps force control and altered muscle activation strategies may be modifiable through neuromuscular training, and this is an area for future research.

Level of evidence

Case–control study, Level III.

     

Hamstring and ACL injuries impacts on hamstring-to-quadriceps ratio of the elite soccer players: A retrospective study

This study aimed to compare the angle-specific (AS) and non-angle-specific (NAS) hamstring to quadriceps conventional and functional ratios between healthy, hamstring- and ACL-injured elite soccer players. One hundred and eleven players (27.42 ± 8.01 years, 182.11 ± 6.79 cm, 75.93 ± 7.25 kg) completed a series of concentric knee flexor and extensor strength in addition to eccentric knee flexor strength was measured at an angular velocity of 60°.s⁻¹. Normalized and raw peak torque values, and the torque-angle profiles were extracted for analysis. Conventional and functional NAS (peak values) and AS (waveform ratios) hamstring to quadriceps ratios were calculated and compared between the groups. Healthy players produced greater functional and conventional ratios compared to players with either ACL or hamstring injury. Players with hamstring injury produced a lower AS functional ratios between 46° and 54° of knee flexion. Players suffering from ACL injury depicted a lower value for the AS functional ratio between 33° and 56° of knee flexion. Although NAS can identify soccer players with previous hamstring or ACL injury, the range where there is a strength deficiency is eluded. With the use of AS the range where the deficiency is present can be identified, and clinicians can benefit from this analysis to design robust rehabilitation protocols.     

ACL reconstruction: patellar tendon versus hamstring grafts—economical aspects

The aim of the present investigation was to compare the costs for the use of patellar tendon versus hamstring tendons as grafts for anterior cruciate ligament (ACL) reconstruction including the different fixation methods. The background is that during recent years there has been a dramatic shift from patellar tendon to hamstring tendons in ACL reconstructions in Sweden. All our patients with ACL reconstructions performed during 1 year (2004) were included. Knee joints numbering 440 in 439 patients were primary ACL reconstructions. A hamstring graft was used in 345 knee joints (78.4%) and a patellar tendon graft in 95 (21.6%) of the patients (Table 2). On average 34 (SD 12.9; range 14–63) ACL reconstructions per surgeon were performed by a total of 14 surgeons. The average cost for patellar tendon procedure was 197 € compared to 436 € for the hamstring procedure. Mean time for surgery in primary reconstructions was 11.5 min shorter (P<0.001) for patellar tendon reconstructions (71.3±31 min) compared to hamstring reconstructions (83.2±27 min). This means a difference in cost of 90 €. The total additional cost (fixation and surgery time) for the hamstring method compared to the patellar tendon method was on an average 329 €. From a strict economic point of view we therefore recommend or at least consider the use of the patellar tendon as a graft in ACL reconstructions.     

用等速测力法评定优秀运动员股四头肌和腘绳肌力量和耐力

研究结果证明:运动员膝关节等速肌力的各项指标均明显大于对照组青年的肌肉力量,P<0.001。在不同项目运动员中,股四头肌力最强为举重运动员,腘绳肌力最大的为短跑运动员。而足球运动员的股四头肌和腘绳肌力相对较弱。膝关节肌肉耐力最好为自行车运动员,举重运动员的耐力则最差。     

The effects of proprioceptive or strength training on the neuromuscular function of the ACL reconstructed knee: a randomized clinical trial

OBJECTIVES: The purpose of this study was to determine the effects of a proprioceptive training program (PT) vs. a strength training (ST) program on neuromuscular function after anterior cruciate ligament (ACL) reconstruction. The second purpose was to establish the determinants of functional ability for the operated limb. METHODS: Ten participants with unilateral ACL reconstructions were randomly assigned to one of the following 12-week training protocols: (1) isotonic ST, and (2) PT. The outcome measures were: (1) peak torque time of the hamstring muscles (PeakTT), (2) average concentric and eccentric torques of the quadriceps and hamstring muscles, (3) one-legged single hop for distance (SLHD), (4) one-legged time hop (TH), and (5) subjective scores. RESULTS: : There was a significant group by time interaction effect for PeakTT (P = 0.017). The PT group demonstrated greater percent change in isokinetic torques than the ST group at the end of the 12 weeks (P < or = 0.05). Participants in both groups demonstrated similar significant gains in functional ability and subjective scores (P < or = 0.014). Quadriceps strength is a determinant of functional ability for the operated limb (R2 = 0.72). CONCLUSIONS: : Both training protocols influenced PeakTT. The beneficial effects of ST on PeakTT appear to be load-dependent, while sufficient practice may be crucial in maintaining PeakTT improvements induced by PT. Proprioceptive training alone can induce isokinetic strength gains. Restoring and increasing quadriceps strength is essential to maximize functional ability of the operated knee joint.