Isokinetic profile of patient with anterior cruciate ligament tear

Muscle function, Lysholm score and hop performance in individuals with clinical indications for the combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee: A cross-sectional study

OBJECTIVE

To evaluate hip and knee muscular function, knee patient-reported outcome measures and hop performance in patients with a clinical indication for combined ACL+ALL reconstruction surgery compared to patients with an isolated ACL reconstruction surgery indication (preoperative phase) and to a control group.

DESIGN

Cross-sectional study.

METHODS

The sample was composed of male individuals, aged between 18 and 59 years, divided into three groups (ACL, ACL+ALL and Control). Isokinetic dynamometry was performed for the flexor and extensor knee muscles and for the hip abductors and adductors. SLHT, COHT and the Lysholm score were performed. Pain, swelling, and thigh trophism were also measured.

RESULTS

The study participants were 89 male individuals: 63 in the injury group and 26 in the control group. After applying the criteria for an ALL reconstruction indication, 33 patients were assigned to the ACL Group and 30 patients to the ACL+ALL Group. Regarding knee and hip muscle function, both groups presented worse results when compared to the control group, however, did not show significant differences compared to each other. Regarding the functional variables, the ACL+ALL group showed a significantly shorter distance achieved in the Crossover Hop Test than the other groups, as well as more pain during the tests.

CONCLUSION

Knee and hip muscular functions are impaired after an ACL injury and do not seem to be influenced or worsened in individuals with greater rotational instability with clinical indications for combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee.

Influence of Anterior Cruciate Ligament Tear on Thigh Muscle Strength and Hamstring-to-Quadriceps Ratio: A Meta-Analysis

Theoretical compensation after anterior cruciate ligament (ACL) tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; P<0.001) and 7.4 N∙m (95% CI: 4.3 to 10.5 N∙m; P<0.001) lower, respectively, on the injured than on the uninjured side. The mean hamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; P<0.001). Conclusively, Decreases were observed in both the quadriceps and hamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees.

Acute effects of static stretching on peak torque and the hamstrings-to-quadriceps conventional and functional ratios

Recent evidence has shown acute static stretching may decrease hamstring-to-quadriceps (H:Q) ratios. However, the effects of static stretching on the functional H:Q ratio, which uses eccentric hamstrings muscle actions, have not been investigated. This study examined the acute effects of hamstrings and quadriceps static stretching on leg extensor and flexor concentric peak torque (PT), leg flexor eccentric PT, and the conventional and functional H:Q ratios. Twenty-two women (mean ± SD age=20.6 ± 1.9 years; body mass=64.6 ± 9.1 kg; height=164.5 ± 6.4 cm) performed three maximal voluntary unilateral isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60 and 180°/s before and after a bout of hamstrings, quadriceps, and combined hamstrings and quadriceps static stretching, and a control condition. Two-way repeated measures ANOVAs (time × condition) were used to analyze the leg extension, flexion, and eccentric PT as well as the conventional and functional H:Q ratios. Results indicated that when collapsed across velocity, hamstrings-only stretching decreased the conventional ratios (P<0.05). Quadriceps-only and hamstrings and quadriceps stretching decreased the functional ratios (P<0.05). These findings suggested that stretching may adversely affect the conventional and functional H:Q ratios.

Anterior cruciate ligament-deficient potential copers and noncopers reveal different isokinetic quadriceps strength profiles in the early stage after injury

BACKGROUND

Isokinetic muscle strength testing using the peak torque value is the most frequently included quadriceps muscle strength measurement for anterior cruciate ligament (ACL)-injured subjects. PURPOSE AND HYPOTHESES: The purpose of this study was to investigate quadriceps muscle performance during the whole isokinetic curve in subjects with ACL deficiency classified as potential copers or noncopers and to investigate whether these curve profiles were associated with single-legged hop performance. We hypothesized that quadriceps muscle torque at other knee flexion angles than peak torque would give more information about quadriceps muscle strength deficits. Furthermore, we hypothesized that there would be significant torque differences between potential copers and noncopers and a significant relationship between angle-specific torque values and single-legged hop performance.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Seventy-six individuals with a complete unilateral ACL rupture within the last 3 months were included. The subjects were classified as potential copers and noncopers. Isokinetic quadriceps muscle tests were performed at 60 deg/s. Mean torque values were calculated for peak torque as well as for specific knee flexion angles. The 1-legged hop and the 6-m timed hop tests were included, and symmetry indices were used.

RESULTS

The peak torque value did not identify the largest quadriceps muscle strength deficit. Rather, these were established at knee flexion angles of less than 40 degrees . There were significant differences in angle-specific torque values between potential copers and noncopers (P < .05). Moderate to strong associations were disclosed between angle-specific torque values and single-legged hop performance, but only for noncopers (r > or = .32-.58).

CONCLUSION

Angle-specific quadriceps muscle torque values of less than 40 degrees of knee flexion provide more information on the quadriceps strength deficits after ACL injury than the commonly used peak torque values. Interpretation of the isokinetic curve profiles seems to be of clinical importance for the evaluation of quadriceps muscle performance after ACL injury.

Thigh muscle weakness in ACL-deficient knees persists without structured rehabilitation

We evaluated whether quadriceps and hamstrings weakness depended on chronicity in amateur athletes with anterior cruciate ligament deficiencies. We hypothesized that the weakness would not recover to the level of healthy control subjects without structured rehabilitation. Secondarily, we asked whether quadriceps and hamstrings side-to-side percent asymmetry in strength was consistent at different stages of chronicity. Thirty-six male amateur athletes forming equal groups of short, intermediate, and long chronicity (mean, 4, 12, and 56 months, respectively) were tested isokinetically against control subjects at 60 degrees per second. Weakness was substantial in both muscle groups and at all times ranging from 32% to 21% compared with the control subjects. However, side-to-side deficits revealed a linear trend of lessening with time. The quadriceps had greater side-to-side asymmetry that ranged from 23% to 10%, whereas the hamstrings asymmetry ranged from 14% to almost 0%. Acquiring symmetric strength earlier than 1 year after injury only occurred in the hamstrings. It can be inferred that participation in organized rehabilitation would minimize the detrimental effects of anterior cruciate ligament rupture on thigh muscle strength.

LEVEL OF EVIDENCE

Prognostic Study, Level II.

Frequency content asymmetry of the isokinetic curve between ACL deficient and healthy knee

The torque-time curve patterns of concentric isokinetic knee extension in anterior cruciate ligament (ACL) deficient patients usually present mid-range irregularities associated with the level of anterior tibial translation. The purpose of this study was to compare the smoothness in isokinetic torque production between the ACL deficient and the healthy knee. Thirty ACL deficient soccer players performed bilaterally five trials of maximum concentric knee extension-flexion at 60 degrees /s on a Biodex dynamometer. The three middle trials (a total of six curves) were retained and submitted to further data processing. Maximum frequency values contained within the 90%, 95% and 99% level of the signal power were calculated for each extension and flexion curve. The frequency content of the ACL deficient side proved to be statistically higher compared to the intact side at all levels of the power spectrum. The percentage differences in the frequency content were 18.8%, 10.6% and 40.0% for knee extension, and 49.5%, 24.5% and 16.3% for knee flexion, for the respective power levels. This indicated higher oscillations and, therefore, more unstable mechanical output of the injured knee. An overall biological interpretation of the present results is based on the notion that disturbed motion is generally connected to poor level of joint functionality.