Knee proprioception following ACL reconstruction; a prospective trial comparing hamstrings with bone-patellar tendon-bone autograft

We prospectively studied knee proprioception following ACL reconstruction in 40 patients (34 men and six women; mean age 31 years). The patients were allocated into two equal groups; group A underwent reconstruction using hamstrings autograft, and group B underwent reconstruction using bone-patellar tendon-bone autograft. Proprioception was assessed in flexion and extension by the joint position sense (JPS) at 15°, 45° and 75°, and time threshold to detection of passive motion (TTDPM) at 15° and 45°, preoperatively and at 3, 6 and 12 months postoperatively. The contralateral healthy knee was used as internal control. No statistical difference was found between the ACL-operated and the contralateral knees in JPS 15°, 45° and 75° at 6 and 12 months, in both study groups. No statistical difference was found between the ACL-operated and the contralateral knees in TTDPM 15° at 6 and 12 months, nor regarding TTDPM 45° at 3, 6 and 12 months, in group A. No statistical difference was found in JPS and TTDPM between the two grafts, at any time period. Knee proprioception returned to normal with ACL reconstruction at 6 months postoperatively, without any statistically significant difference between the autografts used.     

Do knee injuries have long-term consequences for isometric and dynamic muscle strength?

To ascertain whether decrements in knee extensor muscle strength persist years after a traumatic ligamentous or meniscal knee injury, with reference to (1) the type of muscle activity, (2) the dominance of injury, and (3) the time since injury, 36 subjects with previous unilateral knee injuries were assessed. Peak voluntary quadriceps muscle strength was measured using the KinCom 500H dynamometer during isometric, concentric (30°·s^–1 and 120°·s^–1) and eccentric contractions (30·s^–1), and the findings for each type of contraction were compared. Significant differences in quadriceps muscle strength were seen between (1) the injured and uninjured limbs during maximal voluntary isometric (P=0.0003), concentric (P<0.0001) and eccentric (P<0.0001) contractions, and (2) the isometric and concentric decrements (P=0.004), and the isometric and eccentric decrements (P=0.012) within the same injured limb. The decrements in eccentric strength were significantly greater if they affected the dominant rather than the non-dominant limb (P=0.0186). No relationship was seen between the time since injury and the degree of isometric or dynamic decrement. Deficits in quadriceps muscle strength remained for a long time after traumatic knee injury, with exercise levels rarely returning to the previously uninjured state. The degree of decrement in muscle strength was dependent upon the type of muscle activity, with concentric and eccentric activity showing greater decrements than those seen with isometric activity. Deficits in the type of activity varied widely in the same individual, and eccentric decrements were significantly worse following dominant knee injuries. Possible explanations for these findings and the implications for rehabilitation following knee injury are discussed. Electronic Publication     

The relationship between performance on the modified star excursion balance test and the knee muscle strength before and after anterior cruciate ligament reconstruction

Objectives

The objective of this study was to evaluate the dynamic balance of the injured and uninjured limb before and after the anterior cruciate ligament (ACL) reconstruction and compare with the control group.

Risk factors for anterior cruciate ligament injury in high school and college athletes

The anterior cruciate (ACL) is the most frequently ruptured ligament of the knee. Some authors have suggested that excessive internal tibial rotation concomitant with hyperpronation of the subtalar joint during stance and inherent knee joint laxity may predispose an athlete to knee injury. Over a period of 2 years, we identified 14 ACL-injured football players and eight ACL-injured female basketball players and gymnasts. We matched them by sport, team, position, and level of competition with 22 athletes without history of ACL injury. Measures of navicular drop, calcaneal alignment, and anterior knee joint laxity with a KT-1000 were obtained from the uninjured knee of the ACL-injured athletes and compared with measures obtained from the ACL-noninjured athletes. ACL-injured athletes had greater amounts of navicular drop, suggesting greater subtalar pronation and greater anterior knee joint laxity. Discriminant analysis and multiple regression indicated that these variables correctly predicted injury status for 87.5% of the females and for 70.5% of all cases. These results suggest that the more an athlete pronates and the greater the anterior knee joint laxity, the greater the association with ACL injury.     

Efficacy of the Star Excursion Balance Tests in Detecting Reach Deficits in Subjects With Chronic Ankle Instability

OBJECTIVE: Chronic instability after lateral ankle sprain has been shown to cause balance deficits during quiet standing. Although static balance assessment in those with ankle instability has been thoroughly examined in the literature, few researchers have studied performance on more dynamic tasks. Our purpose was to determine if the Star Excursion Balance Tests (SEBTs), lower extremity reach tests, can detect deficits in subjects with chronic ankle instability. DESIGN AND SETTING: We performed all testing in a university athletic training facility. We tested lower extremity reach using the SEBTs, which incorporates single-leg stance with maximal reach of the contralateral leg. SUBJECTS: Twenty subjects with unilateral, chronic ankle instability (age = 19.8 +/- 1.4 years, height = 176.8 +/- 4.5 cm, mass = 82.9 +/- 21.2 kg) and 20 uninjured subjects matched by sex, sport, and position (age = 20.2 +/- 1.4 years, height = 178.7 +/- 4.1 cm, mass = 82.7 +/- 19.9 kg). MEASUREMENTS: We measured the reach distances in centimeters (cm) and averaged 3 reaches in each of the 8 directions while the subjects stood on each leg for data analysis. RESULTS: The group with chronic ankle instability demonstrated significantly decreased reach while standing on the injured limb compared with the matched limb of the uninjured group (78.6 cm versus 82.8 cm). Additionally, subjects with chronic ankle instability reached significantly less when standing on their injured limbs as compared with their uninjured limbs (78.6 cm versus 81.2 cm). CONCLUSIONS: The SEBTs appear to be an effective means for determining reach deficits both between and within subjects with unilateral chronic ankle instability.     

Effects of knee bracing on postural control after anterior cruciate ligament rupture

Study designRandomized clinical trial.ObjectivesTo investigate the effects of functional knee braces on postural control in patients with anterior cruciate ligament (ACL) rupture.BackgroundACL rupture leads to both mechanical knee instability and deficits in proprioception. Although elastic knee braces do not increase mechanical stability, patients report improved stability when wearing a brace. Elastic braces were found to reduce the loss of proprioception. It is, however, still unclear whether they also improve postural control, which involves the processing of proprioceptive input at a higher level.MethodsWe studied 58 patients with isolated unilateral ACL rupture using computerized dynamic posturography and compared overall stability index (OSI) scores for injured and uninjured legs with and without a knee brace. In addition, patients were classified as copers and non-copers depending on knee function.ResultsWithin subjects, OSI scores were 3.0 ± 1.1° for uninjured legs when unbraced, 2.8 ± 1.3° for uninjured legs when braced (p = 0.17), 3.7 ± 1.5° for unbraced injured legs, and 2.9 ± 1.3° for braced injured legs (p < 0.001). For the injured legs of copers and non-copers, OSI scores were 3.4° ± 1.2° for copers and 4.0° ± 1.6° for non-copers in the unbraced condition (p = 0.11) and 2.7 ± 1.0° for copers and 3.1 ± 1.4° for non-copers in the braced condition (p = 0.26).ConclusionElastic knee braces increase postural stability by approximately 22% in patients with ACL rupture. There was no difference in postural stability between uninjured and injured legs in the braced condition. One possible explanation is that bracing improves both proprioception and postural control.Level of evidenceControlled clinical trial, level 2a.     

Risk factors for residual anterolateral rotational instability after double bundle anterior cruciate ligament reconstruction: Evaluation by quantitative assessment of the pivot shift phenomenon using triaxial accelerometer

BackgroundExact knowledge of risk factors for residual anterolateral rotatinoal instability (ALRI) after anterior cruciate ligament (ACL) reconstruction is limited. The purpose of this study was to analyse possible risk factors for ALRI after ACL reconstruction.MethodsQuantitative assessment of the pivot shift phenomenon by measuring tibial acceleration was performed in 46 patients during primary double-bundle ACL reconstructions. The absolute value of the acceleration of the injured knee after provisional fixation of the ACL grafts (‘absolute residual acceleration’) and the subtraction of the acceleration of the uninjured knee from absolute residual acceleration (‘relative residual acceleration’) were defined as indicators for residual ALRI. The associations between these indicators and nine candidate risk factors were analysed using univariate and multiple regression analyses.ResultsMultiple regression analysis revealed that absolute residual acceleration was positively associated with both preoperative acceleration difference between injured and uninjured knees (β = 0.469, P < 0.001) and tibial acceleration of the uninjured knee (β = 0.597, P < 0.001). Relative residual acceleration was also positively associated with preoperative acceleration difference between injured and uninjured knees (β = 0.446, P < 0.001), but was negatively associated with tibial acceleration of the uninjured knee (β = − 0.763, P < 0.001).ConclusionsPatients with larger preoperative side-to-side difference of the pivot shift phenomenon have higher risk for both absolute and relative residual ALRIs after ACL reconstruction, whereas patients with larger pivot shift phenomenon in their uninjured knees are at higher risk for absolute residual ALRI but not for relative residual ALRI.     

Evaluating rotational kinematics of the knee in ACL reconstructed patients using 3.0 Tesla magnetic resonance imaging

IntroductionInjury to the anterior cruciate ligament (ACL) is common. While prior studies have shown that surgical reconstruction of the ACL can restore anterior–posterior kinematics, ACL-injured and reconstructed knees have been shown to have significant differences in tibial rotation when compared to uninjured knees. Our laboratory has developed an MR compatible rotational loading device to objectively quantify rotational stability of the knee following ACL injuries and reconstructions. Previous work from our group demonstrated a significant increase in total tibial rotation following ACL injuries. The current study is a prospective study on the same cohort of patients who have now undergone ACL reconstruction. We hypothesize that ACL reconstructed knees will have less tibial rotation relative to the pre-operative ACL deficient condition. We also hypothesize that ACL reconstructed knees will have greater rotational laxity when compared to healthy contralateral knees.MethodsPatients. Six of the ACL injured patients from our initial study who had subsequently undergone ACL reconstruction were evaluated 8.1 ± 2.9  months after surgery. All patients underwent single-bundle ACL reconstruction using anteromedial portal drilling of the femoral tunnel with identical post-operative regimens.Magnetic Resonance (MR) Imaging. Patients were placed in a supine position in the MR scanner on a custom-built loading device. Once secured in the scanner bore, an internal/external torque was applied to the foot. The tibiae were semi-automatically segmented with in-house software. Tibial rotation comparisons were made within subjects (i.e. side-to-side comparison between reconstructed and contralateral knees) and differences were explored using paired sample t-tests with significance set at p = 0.05.ResultsRegarding tibial rotation, in the ACL deficient state, these patients experienced an average of 5.9 ± 4.1° difference in tibial rotation between their ACL deficient and contralateral knees. However, there was a ?0.2 ± 6.1° difference in tibial rotation of the ACL reconstructed knee when compared to the contralateral uninjured knee. Regarding tibial translation, ACL deficient patients showed a difference of 0.75 ± 1.4mm of anterior tibial translation between injured and healthy knees. After ACL reconstruction, there was a 0.2 ± 1.1mm difference in coupled anterior tibial translation of the ACL reconstructed knee compared to the contralateral knee. No significant differences in contact area between the two time points could be discerned.DiscussionThe objective of our study was to assess the rotational laxity present in ACL reconstructed knees using a previously validated MRI-compatible rotational loading device. Our study demonstrated that ACL reconstruction can restore rotational laxity under load. This may speak to the benefit of an anteromedial drilling technique, which allows for a more horizontal and anatomically appropriate graft position.     

Posterolateral corner reconstruction in combined injuries of the knee: Improved stability with Larson's fibular sling reconstruction and comparison with LaPrade anatomical reconstruction

BackgroundThe goal of this prospective cohort study was to present the clinical results of a two-year follow-up of a Larson's posterolateral corner reconstruction (fibular sling) in patients with symptomatic instability of the knee. These data were compared with data of an anatomical reconstruction of the posterolateral corner as described by LaPrade et al. (combined tibial tunnel and fibular sling) [1].MethodsEleven patients underwent a Larson's posterolateral corner reconstruction. Cruciate ligament ruptures were reconstructed if present. Multiple subjective knee outcome scores (VAS satisfaction score, Tegner, Lysholm, Noyes score, and IKDC subjective knee score) were obtained pre-operatively and two years after surgery. Laxity of the joint was measured using bilateral varus stress radiographs.ResultsAll patients had concomitant ACL or PCL surgery. VAS satisfaction, the Tegner, Noyes and the IKDC subjective knee score all improved significantly. Median varus laxity of the injured knee on varus stress radiographs improved significantly from 6.2° (3.1–10.1) to 3.9° (1.1–5.7), p = .0076. Post-operative varus laxity did not return to the level of the uninjured knee: 2.7° (1–5.7), p = .028. In comparison with our data on the reconstruction technique according to LaPrade, no statistically significant differences in clinical outcome were observed.ConclusionReconstruction of the posterolateral corner in combined injuries of the knee using a Larson fibular sling technique results in improved varus stability but not to the level of the uninjured knee. Functional knee scores improved significantly.We found no differences in functional and radiological outcome between the Larson's fibular sling reconstruction and LaPrade anatomical reconstruction.Level of evidenceIV     

Changes in stretch reflex excitability are related to "giving way" symptoms in patients with anterior cruciate ligament rupture

A rupture of the anterior cruciate ligament (ACL) usually leads to an altered stretch reflex excitability of the thigh muscles that stabilize the knee. The purpose of this study was to quantitatively assess reflex activity in the m. semitendinosus/semimembranosus after anterior tibial translation in 21 patients with isolated ACL ruptures. The patients were divided into a group with "giving way" symptoms (noncopers, n = 12) and a group without "giving way" symptoms (copers, n = 9). While the patients were standing upright with 30 degrees knee flexion, a force of 300 N was applied to the knee to induce posterior-anterior tibial translation. Activity of m. semitendinosus/semimembranosus was measured using surface electromyography (EMG). A linear potentiometer was placed on the tibial tuberosity and measured maximum tibial translation during standing (i.e., functional condition). In addition, knee laxity was assessed with a KT1000 arthrometer under passive conditions. After ACL rupture, the short-latency response (SLR) latency remained unchanged (P = 0.21), whereas for the medium-latency response (MLR) it was significantly longer (P < 0.001). Significantly longer MLR latencies were noted for noncopers compared with copers (P < 0.01), whereas SLR latencies were similar. Significant differences between healthy and injured legs were noted after tibial translations using KT1000 (P < 0.001) and during stance (P < 0.001). Mechanical knee instability was found to be unchanged between copers and noncopers (KT1000: P = 0.97; tibial translation: P = 0.31). These results indicate that ACL rupture is associated with altered stretch reflex excitability, which may lead to "giving way" symptoms, and that altered stretch reflex excitability may be more important for the development of "giving way" than the mechanical instability of the knee.     

Functional ultrasonography in the diagnosis of acute anterior cruciate ligament injuries: A field study

Functional ultrasonography is a rapid and inexpensive method of diagnosing anterior cruciate ligament (ACL) injuries. In previous studies, we assessed the diagnostic accuracy of this innovative method by experienced sonographers. The objective of the present study was to investigate whether an examiner without specialist expertise in arthrosonography can achieve similar positive results and whether this technique is effective as a screening tool that can help reduce the number of undetected ACL injuries.After a short period of training, a single examiner prospectively measured anterior tibial translation by ultrasonography in the injured and healthy knees of 41 patients with acute knee trauma. An ACL rupture was presumed to be present if the side-to-side difference in tibial translation exceeded 1 mm (ΔD > 1 mm). All patients who were enrolled in the study underwent arthroscopy or at least magnetic resonance imaging (MRI).Ultrasonography revealed the presence of an ACL lesion in 32 of 33 patients with arthroscopically confirmed ACL rupture (sensitivity: 97%, specificity: 87.5%). The mean side-to-side differences (ΔD) between injured (3.8 mm ± 1.5 mm) and uninjured ACLs (0.1 mm ± 0.7 mm) were statistically significant (p < 0.05).Our study shows that an examiner without specialist knowledge in ultrasonography can accurately diagnose acute ACL injuries using functional ultrasonography. No additional mechanical tests (KT-1000/KT-2000) or MRI examinations are required. Functional ultrasonography is easy to learn and ensures a high level of diagnostic accuracy. It is well suited for applications in private practices and smaller hospitals with basic medical/surgical care.     

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex

Summary The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Crosslimb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity.     

Rotational laxity after anterior cruciate ligament injury by kinematic evaluation of clinical tests

Despite the numerous studies on anterior cruciate ligament biomechanics and clinical tests, some disagreements still exist in the literature on the role of ACL in restraining rotations and which kinematic test after ACL injuries is the most suitable to evaluate this instability. This work analyses the capability of passive clinical and stress tests to detect an ACL state quantifying rotational instability. The study was conducted on animal knees with a new protocol. We found that an internal-external stress test can give a useful indication on the ACL state when used to estimate the side to side differences while varus-valgus laxity and secondary motions in standard kinematic tests did not seem to be affected by ACL injury. The kinematic protocol performed could be used intra-operatively to quantify rotations, allowing a more accurate evaluation of knee instability to guide surgical reconstruction and improve its final outcome.     

Human hip and knee torque accommodations to anterior cruciate ligament dysfunction

It has been postulated that the adaptations of lower extremity function exhibited by anterior cruciate ligament (ACL) deficient and post-ACL surgical patients represent early accommodations to the loss of ACL function after injury so that excessive anterior displacement of the tibia is prevented. Prior studies have suggested that compensation patterns in ACL deficient and post-ACL surgical subjects may affect joint moments of the knee as well as the hip. However, the variance in knee and hip forces between ACL deficient, post-surgical ACL and uninjured groups has not been clearly elucidated. The purpose of this study was to assess hip:knee extensor torque ratios relative to anterior tibia shear in pre-surgical-ACL deficient, post-surgical and uninjured subjects. Measurements of hip and knee joint moments and anterior tibia shear were recorded from 45 injured and uninjured subjects (21 men, 24 women) during lower extremity, variable resistance exercise. Anterior tibia shear was computed by decomposing joint moments and reaction forces according to a model derived from cadaver knee dissections and radiography, in combination, to estimate the tibio-femoral compressive and shear forces generated by the patellar tendon at various angles throughout the knee joint range. Three groups of subjects were studied: recently injured ACL deficient pre-surgical subjects who were scheduled for immediate surgery (PRE; n=15); post-surgical subjects who had undergone ACL reconstructive surgery at least 1 year prior to testing (POST; n=15); and uninjured controls (CON; n=15). All PRE and POST subjects had a normal contralateral limb. Tests were conducted under six conditions: 1 and 1.5 Hz cadence and maximal speed at 33% and 50% one repetition maximum resistance. The results revealed that the hip:knee ratios were significantly greater for the post-ACL surgical group than the PRE and CON groups (P < 0.01; P < 0.03). There were significant negative correlations between the hip extensor:knee extensor torque ratios and maximal anterior tibia shear. across all groups. The hip:knee extensor torque ratio increased with decreased anterior tibia shear in all groups with significant correlations ranging from −0.55 to −0.88 (P < 0.01) for the injured limbs of PRE and POST groups, and −0.64 to −0.78; (P < 0.01) for the CON group. The highest overall correlations were found for the post-surgical subjects. The results revealed that anterior tibia shear declined significantly with speed (P < 0.01) in all groups. However, the converse was true for the hip:knee extensor torque ratio across speeds. The ratio increased significantly with speed (P < 0.001) for all groups at the 33% and 50% resistances. The results suggest (1) that post-ACL surgical subjects appear to accommodate to ACL substitution by using hip extensors to a significantly greater extent than the uninjured controls in closed-chain lower extremity exercise; (2) that the hip:knee extensor torque ratio is significantly related to the magnitude of anterior tibia shear; and (3) that the anterior tibia shear is significantly reduced as speed increases in closed-chain lower extremity exercise. Accepted: 30 April 2000     

Kinematics and muscular responses to a ramp descent in the ACL deficient knee

BACKGROUND AND PURPOSE: Descent of a ramp has been shown to induce large anterior shear forces on the knee joint. Compensatory muscle responses observed in individuals following an anterior cruciate ligament (ACL) injury are believed to be adopted for the purpose of reducing these forces at the knee, in the absence of the mechanical restraint previously provided by the ACL. As such, examining the kinematics and muscle responses of ACL deficient individuals during ramp descent may provide further insight into strategies used by this population to compensate for anterior shear forces at the knee. METHODS: Eight ACL deficient individuals were studied, in comparison to a healthy CONTROL group (N=8), during the descent of a 20 degrees ramp. Kinematics and electromyography were recorded for the injured lower limb of ACLD and matched limb of healthy control individuals. RESULTS: ACLD individuals produced altered knee kinematics at heel contact only. Knee motion through stance and swing were similar to CONTROL individuals. ACLD individuals produced significantly greater vastus lateralis and gastrocnemius total muscle activity, but decreased total biceps femoris activity. No significant differences were observed for the timing of peak muscle activity or the magnitude at this point between ACLD and CONTROL. DISCUSSION AND CONCLUSION: Greater total muscle activity of vastus lateralis implies that greater force contributions from this muscle were used by ACLD in comparison to CONTROL in response to the ramp. These observations reinforce that quadriceps avoidance is not used by ACLD individuals to reduce anterior shear forces at the knee joint. Rather, vastus lateralis may be used to reduce internal tibial rotation in extreme loading situations.     

Arthroscopic intra and extra articular ACL reconstruction with gracilis and semitendinosus tendons with early resumption of sport. Results at minimum two years follow-up

The purpose of this study was to evaluate the results at minimum 2 years follow-up of our original hamstrings technique, with intra and extra articular ACL plasty, followed by an aggressive rehabilitation program. Forty young sports practising patients were prospectively selected. IKDC score, Lysholm scale score as well as KT 2000 and isokinetic tests with a Lido machine (Lido CA) were used for patient evaluation. Ninety percent of the patients had a negative Lachman test and 85% experienced no pivot shift. Valgus rotation was 1+ in 22.5% of the cases. KT 2000 evaluation showed a similar trend in the three tests performed, with an average injured/uninjured difference of 2.1 mm. The results confirm our original hamstrings technique efficacy and its low morbidity. Patients with residual valgus laxity in relation to partial MCL tears had significantly higher KT parameters and consequently less favourable outcome. An aggressive rehabilitation reduces sensitively the sport recovery time without affecting knee stability.     

抗阻训练对绝经后女性身体成分、膝关节肌肉力量及动态平衡能力的影响

目的：探讨抗阻训练对绝经后女性身体成分、膝关节屈伸肌力及动态平衡能力的影响。方法：将25 名绝 经女性随机分为抗阻训练组和对照组,抗阻训练前后测试绝经后女性身体成分（ 体质量、体脂肪量、肌肉量、左 右下肢肌肉量）,左、右膝关节屈、伸肌力及动态平衡能力。结果：12 周抗阻训练可使绝经后女性体脂肪量显著 下降,左右下肢肌肉量及全身肌肉量均显著增加,而体质量在抗阻训练前后无显著差异;此外,12 周抗阻训练可 使绝经后女性左、右膝关节屈、伸肌肌力显著增加,闭眼状态下总体稳定指数、前后方向稳定指数及左右方向稳 定指数显著下降。结论：12 周抗阻训练可显著降低绝经后女性身体脂肪量、增加下肢肌肉量及膝关节肌肉力量, 改善动态平衡能力,对于预防绝经后女性跌倒及提高绝经后女性生存质量有重要意义。     

Changes in muscle strength and EMG median frequency after anterior cruciate ligament reconstruction

The purpose of this study was to monitor neuromuscular changes in quadriceps femoris muscle at 1 and 3 months after anterior cruciate ligament reconstruction (ACLR). Changes in isometric muscle strength (MVC), voluntary activation and surface electromyogram (EMG) parameters were examined in relation to knee stability, pain and swelling in 31 patients (25 M, 6 F) mean (SD) 30(8) years. Physically inactive (RC) and sports participants (SC) acted as controls. Median frequency (Hz) and amplitude (mV) of rectus femoris using Fast Fourier Transform (FFT) 2(11) was calculated during 5-s isometric contractions at 100, 75, 50 and 25% of MVC. One month after surgery, a significant correlation (P < 0.01) was found between activation (%) and MVC of injured knee extensors. By 3 months, most patients were pain free and had achieved full activation but still had muscle weakness. At 1 and 3 months post-surgery and for all levels of MVC contraction, the median frequencies of the injured limbs were significantly lower (P < 0.05) compared to the SC group as were those of the RC group. There was a significant lowering of the median frequencies of the uninjured limbs compared to the SC group at 75 and 100% of MVC. The EMG amplitude of the uninjured and injured limbs mirrored those of the SC and RC groups, respectively. These results support the view that muscle activation patterns were altered following ACL injury and surgical repair and may contribute to subsequent changes in muscle fibre properties during detraining and subsequent retraining.     

Effect of knee flexion angle on ground reaction forces,knee moments and muscle co-contraction during an impact-like deceleration landing: Implications for the non-contact mechanism of ACL injury

Investigating landing kinetics and neuromuscular control strategies during rapid deceleration movements is a prerequisite to understanding the non-contact mechanism of ACL injury. The purpose of this study was to quantify the effect of knee flexion angle on ground reaction forces, net knee joint moments, muscle co-contraction and lower extremity muscles during an impact-like, deceleration task. Ground reaction forces and knee joint moments were determined from video and force plate records of 10 healthy male subjects performing rapid deceleration single leg landings from a 10.5 cm height with different degrees of knee flexion at landing. Muscle co-contraction was based on muscle moments calculated from an EMG-to-moment processing model. Ground reaction forces and co-contraction indices decreased while knee extensor moments increased significantly with increased degrees of knee flexion at landing (all p < 0.005). Higher ground reaction forces when landing in an extended knee position suggests they are a contributing factor in non-contact ACL injuries. Increased knee extensor moments and less co-contraction with flexed knee landings suggest that quadriceps overload may not be the primary cause of non-contact ACL injuries. The results bring into question the counterbalancing role of the hamstrings during dynamic movements. The soleus may be a valuable synergist stabilizing the tibia against anterior translation at landing. Movement strategies that lessen the propagation of reaction forces up the kinetic chain may help prevent non-contact ACL injuries. The relative interaction of all involved thigh and lower leg muscles, not just the quadriceps and hamstrings should be considered when interpreting non-contact ACL injury mechanisms.     

Anterior cruciate ligament repair with internal brace augmentation: A systematic review

BackgroundPrimary repair of anterior cruciate ligament (ACL) ruptures has re-emerged as a treatment option for proximal tears, with internal brace augmentation often utilised. The aim of this study is to provide an overview of the current evidence presenting outcomes of ACL repair with internal bracing to assess the safety and efficacy of this technique.MethodsAll studies reporting outcomes of arthroscopic primary repair of proximal ACL tears, augmented with internal bracing from 2014-2021 were included. Primary outcome was failure rate and secondary outcomes were subjective patient reported outcome measures (PROMs) and objective assessment of anteroposterior knee laxity.ResultsNine studies were included, consisting of 347 patients, mean age 32.5 years, mean minimum follow up 2 years. There were 36 failures (10.4%, CI 7.4% - 14.1%). PROMs reporting was variable across studies. KOOS, Lysholm and IKDC scores were most frequently used with mean scores > 87%. The mean Tegner and Marx scores at follow-up were 6.1 and 7.8 respectively. The mean side to side difference measured for anteroposterior knee laxity was 1.2mm.ConclusionsThis systematic review with meta-analysis shows that ACL repair with internal bracing is a safe technique for treatment of proximal ruptures, with a failure rate of 10.4%. Subjective scores and clinical laxity testing also revealed satisfactory results. This suggests that ACL repair with internal bracing should be considered as an alternative to ACL reconstruction for acute proximal tears, with the potential benefits of retained native tissue and proprioception, as well as negating the need for graft harvest.