The anterior cruciate ligament-deficient knee: compensatory mechanisms during downhill walking

Level and Downhill Walking to Assess Implant Functionality in Bicruciate- and Posterior Cruciate-Retaining Total Knee Arthroplasty

BACKGROUND

The goal of this study is to set up a functional motion analysis test to examine effects of the anterior cruciate ligament in total knee arthroplasty (TKA) patients by comparing knee kinematics, kinetics, and muscle activation patterns during level and downhill walking for patients with posterior cruciate-retaining (PCR) and bicruciate-retaining (BiCR) TKAs.

METHODS

Motion and electromyography (EMG) data were collected for 12 subjects (4/8 male/female, 64 ± 11 years, 31.3 ± 7.3 body mass index, 6/6 right/left) with BiCR TKAs and 15 subjects (6/9 male/female, 67 ± 7 years, 30.5 ± 5.1 body mass index, 4/11 right/left) with PCR TKAs during level and downhill walking using the point cluster marker set and surface electrodes placed on the vastus medialis obliquus, rectus femoris, biceps femoris, and semitendinosus muscles.

RESULTS

Level walking exhibited no significant differences in knee kinematics, kinetics, or EMG patterns. During downhill walking, BiCR subjects had significantly lower peak muscle activity in the vastus medialis obliquus and rectus femoris (P = .045 and .018, respectively), a trending higher peak knee flexion moment (2.0 ± 0.6% BW*HT vs 1.5 ± 0.6% BW*HT, P = .076), and significantly more knee flexion at heel strike (5.1° ± 4.7° vs 1.8° ± 2.8°, P = .044) compared with PCR subjects.

CONCLUSION

Anterior cruciate ligament retention led to altered muscle recruitment during downhill walking in BiCR subjects compared with PCR subjects; thus, BiCR TKAs may offer some neuromuscular benefits for stabilizing the knee joint. In conclusion, level and downhill walking knee kinematics and kinetics combined with corresponding quadriceps and hamstrings EMG signals begin to build an overall picture of implant functionality.

Knee muscle activity during gait in patients with anterior cruciate ligament injury: a systematic review of electromyographic studies

PURPOSE

This review compared knee muscle activity between ACL-deficient (ACLD) patients and healthy controls during gait, to find out whether the available electromyography (EMG) studies support Quadriceps (Q-ceps) inhibition or hamstring facilitation during gait in ACLD patients.

METHOD

A systematic review was conducted to retrieve the EMG studies of knee muscles during gait in ACLD patients. Cochrane library, PubMed, Medline, Ovid, CINAHL and Science Direct databases were searched entries from 1995 through October 2014 using the terms "anterior cruciate ligament" OR "ACL", "electromyography" Or "EMG" "gait" Or "walking". Articles that assessed subjects with ACL rupture that used surface EMG to assess the knee muscle activity were included. The quality of the included papers was assessed using the Critical Appraisal Skills Programme tool for observational studies.

RESULT

In total, 13 studies met the inclusion criteria. Seven studies consistently found no significant difference in magnitude of activity or timing of Q-ceps muscle between the chronic ACLD patients and control subjects. Two studies on acute ACLD patients and three studies on ACLD patients with unstable knee found the significantly reduced Q-ceps activity compared to control subjects. Six studies showed the significantly greater hamstring activity, and three studies found prolonged duration of activity in ACLD patients compared to the control subjects.

CONCLUSION

This review highlighted that the results of the studies are in favour of increased hamstring muscular activity. However, decreased Q-ceps activation exists in the acute stage and in ACLD patients that experience knee instability (non-copers).

LEVEL OF EVIDENCE

III.

Inter-Segmental Coordination Pattern in Patients with Anterior Cruciate Ligament Deficiency during a Single-Step Descent

Anterior cruciate ligament injury is a debilitating pathology which may alter lower limb coordination pattern in both intact and affected lower extremities during activities of daily living. Emerging evidence supports the notion that kinematic variables may not be a good indicator to differentiate patients with anterior cruciate ligament deficiency during step descent task. The aim of the present study was to examine alterations in kinematics as well as coordination patterns and coordination variability of both limbs of these patients during a single step descent task. Continuous relative phase technique was used to measure coordination pattern and coordination variability between a group of anterior cruciate ligament deficient (n = 23) and a healthy control group (n = 23). A third order polynomial Curve fitting was utilized to provide a curve that best fitted to the data points of coordination pattern and coordination variability of the healthy control group. This was considered as a reference to compare to that of patient group using nonlinear regression analysis. The results of the present study demonstrated an altered coordination pattern of the supporting shank-thigh and the stepping foot-shank couplings in anterior cruciate ligament deficient subjects. It was further noticed that there was an increased coordination variability in foot-shank and shank-thigh couplings of both supporting and stepping legs. There was no significant difference in the hip, knee and ankle joints kinematics in either side of these patients. Anterior cruciate ligament deficient individuals showed altered strategies in both intact and affected legs, with increased coordination variability. Kinematic data did not indicate any significant difference between the two groups. It could be concluded that more sophisticated dynamic approach such as continuous relative phase would uncover discrepancies between the healthy and anterior cruciate ligament deficient individuals.

The effect of anterior cruciate ligament rupture on the timing and amplitude of gastrocnemius muscle activation: a study of alterations in EMG measures and their relationship to knee joint stability

Changes in hamstring and quadriceps activity are well known in individuals with anterior cruciate ligament deficiency (ACLD) to potentially compensate for knee joint instability. However, few studies have explored gastrocnemius activity or its relationship to knee stability. The purpose of this study was therefore to examine the activation characteristics of medial gastrocnemius (MG) in ACLD subjects and relate any changes to knee joint laxity. Two subject cohorts were assessed: those with unilateral ACLD (n=15) and uninjured control subjects (n=11). Surface EMG of the left and right MG were recorded during a controlled single leg hop on each limb. Onset and offset of MG activation relative to take-off, during flight and landing were calculated as well as muscle activity (RMS). Passive antero-posterior knee laxity was measured with a KT1000 arthrometer during a maximal manual displacement test. Medial gastrocnemius activity on the injured side of ACLD participants demonstrated significantly prolonged activation in preparation to hop, minimal muscle inactivity prior to take-off, and increased duration of overall muscle activity when compared to the uninjured side and control subjects (p<0.05). Significant positive correlations were found between passive knee joint laxity and prolonged activation prior to knee bend. RMS of the muscle signal was not significantly different between limbs. Overall, MG on the ACLD side demonstrated longer activation, with minimal rest during the hop test, which may be an attempt to maintain knee stability. Furthermore, the strong relationship between knee laxity and prolonged muscle activation suggests that individuals with a loss of knee stability are more reliant on active control of the gastrocnemius muscle.

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.

Proprioceptive deficits of the lower limb following anterior cruciate ligament deficiency affect whole body steering control

The role of lower limb proprioception in the steering control of locomotion is still unclear. The purpose of the current study was to determine whether steering control is altered in individuals with reduced lower limb proprioception. Anterior cruciate ligament deficiency (ACLD) results in a decrease in proprioceptive information from the injured knee joint (Barrack et al. 1989). Therefore the whole body kinematics were recorded for eight unilateral ACLD individuals and eight CONTROL individuals during the descent of a 20 degrees incline ramp followed by either a redirection using a side or cross cutting maneuver or a continuation straight ahead. Onset of head and trunk yaw, mediolateral displacement of a weighted center of mass (COM(HT)) and mediolateral displacement of the swing foot were analyzed to evaluate differences in the steering control. Timing analyses revealed that ACLD individuals delayed the reorientation of body segments compared to CONTROL individuals. In addition, ACLD did not use a typical steering synergy where the head leads whole body reorientation; rather ACLD individuals reoriented the head, trunk and COM(HT) in the new direction at the same time. These results suggest that when lower limb proprioceptive information is reduced, the central nervous system (CNS) may delay whole body reorientation to the new travel direction, perhaps in order to integrate existing sensory information (vision, vestibular and proprioception) with the reduced information from the injured knee joint. This control strategy is maintained when visual information is present or reduced in a low light environment. Additionally, the CNS may move the head and trunk segments as, effectively, one segment to decrease the number of degrees of freedom that must be controlled and increase whole body stability during the turning task.

The clinical significance of electromyography normalisation techniques in subjects with anterior cruciate ligament injury during treadmill walking

This study investigated the clinical interpretation of three electromyographic (EMG) normalisation techniques to detect neuromuscular alterations in patients diagnosed with anterior cruciate ligament knee injury during treadmill walking. The EMG signal was normalised using the mean value during the gait cycles (MEA), the maximum value during the gait cycles (MAX), and a maximum voluntary isometric contraction (MVC) test in 16 male and female subjects. The MAX method detected an increase in total muscle activity in the injured limb rectus femoris (11.6%; P=0.02) while the MVC method detected decreased injured limb gastrocnemius medialis (GM) overall muscle activity (34.4%; P=0.02). The MAX method identified decreased GM activity in three portions of the gait cycle. This study indicates the importance of choosing the appropriate normalisation technique since its choice will change outcome measures and subsequent clinical interpretation.

The benefits of wearing a compression sleeve after ACL reconstruction

PURPOSE

It was the purpose of the present study to examine the possibility of increased muscle coordination after anterior cruciate ligament (ACL) reconstruction through the wearing of a compression sleeve.

METHODS

Thirty-six patients were studied who had undergone unilateral ACL reconstruction at least 12 months previously. All subjects were required to perform a 10-cm standing drop jump from an elevated platform onto a force plate, to land on one leg, and thereafter maintain a one-legged balance for 25 s. This task was repeated three times without and three times with an elastic compression sleeve worn on the reconstructed limb. For analysis, the task was partitioned into a landing phase (150 ms), an adjusting phase (10s), and a balancing phase (10s). The peak impact loadings were measured in each direction (Fx, Fy, and Fz) during landing, while force-time integrals (intFz, intFy, and intFz) and root mean square (RMS) error of these forces were calculated for the adjusting and balancing phases. The path length and RMS of the center of pressure coordinates (Ax and Ay) were obtained for the adjusting and balancing phases combined.

RESULTS

Drop landings with the bandage produced significantly larger (P < 0.001) peak ground reaction forces in the vertical and anteroposterior direction, suggesting increased subject confidence in their knee. Wearing the knee bandage also enabled the patients to reduce all measured parameters in the anteroposterior direction (rmsFx, intFx, rmsAx) during both the adjusting and balancing phases (P < 0.001 ). A significant reduction in the center of pressure path length further indicated an enhanced steadiness during the one-legged stance.

CONCLUSIONS

It was concluded that a compression sleeve improved the total integration of the balance control system and muscle coordination.