Gait mechanics in chronic ACL deficiency and subsequent repair

OBJECTIVE: To determine how normal gait patterns may change as a result of chronic anterior cruciate ligament deficiency and subsequent reconstructive surgery. DESIGN: Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and 3 months following reconstructive surgery, and 10 uninjured controls. BACKGROUND: There is controversy whether persons with chronic anterior cruciate ligament deficiency develop a "quadriceps avoidance" pattern and how anterior cruciate ligament reconstructive surgery influences gait mechanics in these same individuals. METHODS: Gait analysis was employed to determine kinematic, kinetic, and muscle Electromyographic data. RESULTS: Prior to surgery, no anterior cruciate ligament deficient subject exhibited a quadriceps avoidance pattern. Following surgery, the subjects exhibited a significantly greater knee extensor moment during early stance as compared to the control group. Prior to and following surgery, anterior cruciate ligament deficient subjects demonstrated a significantly greater hip extensor moment possibly to reduce anterior tibial translation. CONCLUSIONS; These data suggest that (1) development of a quadriceps avoidance pattern is less common than previously reported, (2) anterior cruciate ligament deficient subjects accommodate through alterations of hip joint mechanics, (3) surgical repair significantly alters lower extremity gait patterns, and (4) re-establishment of pre-injury gait patterns takes longer than 3 months to occur. RELEVANCE: The results suggest that chronic anterior cruciate ligament deficient subjects do not exhibit a quadriceps avoidance gait pattern. Surgical intervention significantly alters lower extremity gait mechanics in a population that has accommodated to anterior cruciate ligament deficiency.     

Bilateral accommodations to anterior cruciate ligament deficiency and surgery

OBJECTIVE To determine bilateral lower extremity joint accommodations during gait in anterior cruciate ligament deficient subjects and uninjured controls. DESIGN: Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and 3 months following reconstructive surgery, and 10 uninjured controls. BACKGROUND: It is possible that bilateral joint accommodations could occur as a result of anterior cruciate ligament injury and in response to surgical repair. Few studies have investigated bilateral joint accommodations to anterior cruciate ligament injury and there is little consistency in the reported results. METHODS: Bilateral lower extremity kinematic and kinetic data were collected from 12 walking trials and inverse dynamics calculations were made to estimate bilateral knee and hip joint angle, moment, and power patterns during the stance phase of gait. RESULTS: Control subjects exhibited asymmetrical hip but symmetrical knee joint moment and power patterns. In contrast, the anterior cruciate ligament deficient subjects exhibited symmetrical hip and asymmetrical knee joint moment and power patterns prior to and following reconstructive surgery. CONCLUSIONS: Gait asymmetry in healthy subjects should not be considered pathological. In addition, chronic anterior cruciate ligament injury results in joint specific, bilateral lower extremity accommodations in gait mechanics. These accommodations persist 3 months following surgical repair.     

Biomechanical changes elicited by an anterior cruciate ligament deficiency during steady rate cycling

OBJECTIVES: To identify any changes to lower limb biomechanics during steady rate cycling as a result of an anterior cruciate ligament deficiency. DESIGN: Comparative study in which healthy and anterior cruciate ligament injured individuals underwent biomechanical analysis during stationary cycling. BACKGROUND: Individuals with an anterior cruciate ligament deficiency often exhibit reductions in the magnitude of quadriceps muscle activity and subsequent knee joint extensor moments during walking. It is not known whether these compensations are present during cycling, an exercise frequently used to retrain anterior cruciate ligament injured individuals. METHODS: Ten healthy and 10 unilateral anterior cruciate ligament deficient individuals participated. All participants were required to cycle for approximately 30 s at each of six different cycling intensities while lower limb EMG, kinetics, and kinematics were collected bilaterally. Before riding, participants performed submaximal isometric contractions to generate normalizing data. RESULTS: In addition to reduced quadriceps activation and net knee joint extensor moments, the anterior cruciate ligament deficient limbs exhibited decreases in linear impulse of the resultant pedal force, knee joint flexor moments, hip and ankle extensor moments, and muscle activity from gluteus maximus. These decreases were counteracted by an increase in output from the anterior cruciate ligament intact limb. CONCLUSION: Anterior cruciate ligament injured individuals exhibited a limb attenuation strategy during cycling activities. RELEVANCE: This study reports lower limb kinetic and electromyographic data from anterior cruciate ligament deficient individuals during stationary cycling, and shows that these individuals exhibit a limb attenuation strategy on the very leg that is undergoing rehabilitation.     

The effect of insufficient quadriceps strength on gait after anterior cruciate ligament reconstruction.

OBJECTIVE: To determine the effect of quadriceps strength and joint stability on gait patterns after anterior cruciate ligament injury and reconstruction. DESIGN: Cross-sectional comparative study in which four groups underwent motion analysis with surface electromyography. BACKGROUND: Individuals following anterior cruciate ligament rupture often demonstrate reduced knee angles and moments during the early stance phase of gait. Alterations in gait can neither be ascribed to instability nor to quadriceps weakness alone when both are present. METHODS: Twenty-eight individuals with complete anterior cruciate ligament rupture (10 patients with acute rupture, 8 patients following reconstruction with quadriceps strength >90% of the uninvolved side [strong-anterior cruciate ligament reconstructed group], and 10 patients after reconstruction with quadriceps strength <80% of the uninvolved side [weak-anterior cruciate ligament reconstructed group]), and 10 uninjured subjects underwent an examination of their lower extremity to collect kinematics, kinetics, and electromyography during walking and jogging. Anterior cruciate ligament reconstruction was arthroscopically assisted and a double loop semitendinosis-gracilis autograft or allograft was used as a graft source. All reconstructed subjects had stable knees, full range of motion, and no effusion or pain at the time of testing (more than three months after surgery). RESULTS: Knee angles and moments of the strong group were indistinguishable from the uninjured group during early stance of both walking and jogging. The weak subjects had reduced knee angles and moments during walking, and jogged similarly to the deficient subjects. Regression analysis revealed a significant effect between early stance phase knee angles and moments and quadriceps strength during both walking and jogging. CONCLUSION: Inadequate quadriceps strength contributes to altered gait patterns following anterior cruciate ligament reconstruction. RELEVANCE: Rapid strengthening following anterior cruciate ligament injury or reconstruction may contribute to a safe return to high-level activities.     

Knee joint moments during stair climbing of patients with anterior cruciate ligament deficiency

OBJECTIVE: To establish the gait adaptations of patients with anterior cruciate ligament deficiency during stair ascent. DESIGN: Joint kinematics and kinetics during stair climbing were measured in both knees of normal subjects and unilateral anterior cruciate ligament deficient patients. BACKGROUND: As there is limited research pertaining to activities other than level walking, the purpose of the current study was to elucidate the gait of patients with anterior cruciate ligament deficiency during stair climbing to determine the effects of the deficiency on knee joint motion and moments as compared with normal knee function. METHODS: A motion analysis system was used to measure and calculate kinematic and kinetic data for six normal subjects and nine patients with unilateral anterior cruciate ligament deficiency during stair ascent on a specially constructed staircase. Left and right leg data were analysed to reveal between-limb differences for each subject. RESULTS: Patients with anterior cruciate ligament deficiency displayed a significant (P < 0.05) reduction of up to 50% in peak knee flexion moments in their involved knee. In the present study where a step height of 15.5 cm was used, peak flexion moments in all subjects' limbs occurred at knee flexion angles of about 40 degrees during single limb support. CONCLUSION: The current study showed that most patients with an anterior cruciate deficient knee adapted their gait during stair ascent. RELEVANCE: As stair climbing is a common activity, its effect on gait is relevant to better understand appropriate treatment and management strategies of patients with anterior cruciate ligament deficient knees.     

Long-term gait biomechanics in level,uphill, and downhill conditions following anterior cruciate ligament reconstruction

BackgroundAltered gait biomechanics have been linked to post-traumatic knee osteoarthritis development following anterior cruciate ligament reconstruction surgery, but the persistence of aberrant gait biomechanics after the first year post-surgery is inconsistent in the literature. Gait biomechanics are typically evaluated on a level surface, but this task may not elucidate discrepancies in individuals further removed from surgery due to the simplicity of the task. Graded surfaces are common in real-world ambulation and may exacerbate aberrant gait biomechanics due to greater mechanical demands.MethodsForty-seven individuals post-anterior cruciate ligament reconstruction (4 ± 3 years post-surgery) and forty-seven uninjured controls completed gait analysis under level, uphill, and downhill conditions on an instrumented treadmill. Outcomes included knee flexion displacement and peak knee flexion angle, vertical ground reaction force, and knee extension and abduction moments.FindingsKnee extension moment and knee flexion displacement were lesser in the surgical limb compared to the contralateral during the downhill condition, with lesser knee flexion displacement also observed during the level condition. Additionally, knee extension moment was less symmetrical in the surgical group during both uphill and downhill conditions compared to controls. Knee flexion displacement was less symmetrical in the surgical group during both level and downhill conditions compared to controls.InterpretationGraded surfaces elucidate aberrant gait biomechanics in individuals more than 1 year post-anterior cruciate ligament reconstruction that are not apparent during level walking. These findings suggest that gait assessment on level surfaces may mask existing deficiencies, and warrant emphasizing ambulation of graded surfaces during anterior cruciate ligament rehabilitation.     

Differences in the movement pattern of a forward lunge in two types of anterior cruciate ligament deficient patients: copers and non-copers

OBJECTIVE: To determine whether differences in the knee joint movement pattern of a forward lunge could be quantified in healthy subjects and in anterior cruciate ligament deficient subjects who were able to return to the same activity level as before their injury (copers) and in those who were not (non-copers). DESIGN: The movement patterns of the injured leg of the coper and non-coper anterior cruciate ligament deficient subjects and the right leg of the control subjects were compared statistically. BACKGROUND: The forward lunge seems to be a less stressful test than the commonly used one-legged hop test, which makes it a possible tool for evaluating and comparing the functional performance of non-copers and copers. METHODS: The movement pattern of a forward lunge was analysed by using a two-dimensional inverse dynamics method. The electromyographic activity of the quadriceps and hamstring muscles were recorded. RESULTS: The non-copers moved more slowly and loaded the knee joint less than the copers and controls. The copers moved more slowly during the knee flexion phase but as fast as the controls during the knee extension. The EMG results suggest that the copers stabilized their knee joint by increasing the co-contraction of the hamstrings during the extension phase. CONCLUSIONS: Differences between the three groups' movement patterns could be quantified. The forward lunge test seems appropriate to discriminate between the knee function in coper and non-coper anterior cruciate ligament deficient subjects. RELEVANCE: Information about the performance of movements, which significantly load the knee joint in coper and non-coper anterior cruciate ligament deficient patients may contribute to a better understanding of dynamic knee joint stabilization, which is relevant in relation to the development of rehabilitation strategies.     

Activity progression for anterior cruciate ligament injured individuals

Background

Functional exercises are important in the rehabilitation of anterior cruciate ligament deficient and reconstructed individuals but movement compensations and incomplete recovery persist. This study aimed to identify how tasks pose different challenges; and evaluate if different activities challenge patient groups differently compared to controls.

Methods

Motion and force data were collected during distance hop, squatting and gait for 20 anterior cruciate ligament deficient, 21 reconstructed and 21 controls.

Findings

Knee range of motion was greatest during squatting, intermediate during hopping and smallest during gait (P < 0.01). Peak internal knee extensor moments were greatest during distance hop (P < 0.01). The mean value of peak knee moments was reduced in squatting and gait (P < 0.01) compared to hop. Peak internal extensor moments were significantly larger during squatting than gait and peak external adductor moments during gait compared to squatting (P < 0.01). Fluency was highest during squatting (P < 0.01). All patients demonstrated good recovery of gait but anterior cruciate ligament deficient adopted a strategy of increased fluency (P < 0.01). During squatting knee range of motion and peak internal knee extensor moment were reduced in all patients (P < 0.01). Both anterior cruciate ligament groups hopped a shorter distance (P < 0.01) and had reduced knee range of motion (P < 0.025). Anterior cruciate ligament reconstructed had reduced fluency (P < 0.01).

Interpretation

Distance hop was most challenging; squatting and gait were of similar difficulty but challenged patients in different ways. Despite squatting being an early, less challenging exercise, numerous compensation strategies were identified, indicating that this may be more challenging than gait.     

Effects of chronic anterior cruciate ligament deficiency on muscle activation patterns during an abrupt deceleration task

OBJECTIVE: This study examined the influence of chronic anterior cruciate ligament deficiency on muscle activation patterns displayed during abrupt deceleration, relative to timing of tibiofemoral shear forces (Fs) generated during the task. DESIGN: Experimental data were collected for both limbs of 11 chronic functional anterior cruciate ligament deficient subjects and 11 matched controls. METHODS: Electromyographic, high speed film and ground reaction force data were sampled as subjects landed in single-limb stance on a force platform after receiving a chest level pass and decelerating abruptly. Temporal characteristics of each muscle burst relative to initial foot-ground contact were derived and Fs were calculated from net joint reaction forces and the patellar tendon force occasioned by the net moments and inertial forces predicted about the knee. RESULTS: Compared to controls, anterior cruciate ligament deficient subjects displayed a delay in hamstring activation so that peak hamstring activity was more synchronous with initial contact and with the high Fs which occurred after initial contact. CONCLUSIONS: It was concluded the delayed hamstring activation was an adaptation developed to enable peak muscle activity to better coincide with the high anterior Fs, thereby stabilizing the injured limb against a giving-way episode via increased joint compression and posterior tibial drawer.     

A clinically applicable EMG-force model to quantify active stabilization of the knee after a lesion of the anterior cruciate ligament

OBJECTIVES: To investigate whether a simple electromyography-force (EMG-force) model can be used to measure different levels of co-contraction about the knee for healthy subjects and patients with an anterior cruciate ligament deficiency. DESIGN: To evaluate an EMG-to-force processing model, two groups of subjects, with and without deficiency of the anterior cruciate ligament, participated in experiments in which surface EMG, kinematics and kinetics about the knee were recorded during isokinetic and functional movements. BACKGROUND: Clinical and biomechanical evidence supports the hypothesis that higher level of co-contraction of quadriceps and hamstrings provide an active stabilization of the knee to compensate for the lost anterior cruciate ligament. To quantify the level of co-contraction, the contribution of both agonist and antagonist muscles to the net joint moment must be known. METHODS: Surface EMG levels were calibrated to moment by means of a limited number of isokinetic contractions about the knee. With these calibration values, an estimate of the muscle moments during a vertical jump were obtained and compared with the net joint moment, calculated with inverse dynamics. Also co-contraction indices were determined. RESULTS: The EMG-force model provided a fair estimate of the net joint moment. The co-contraction index in anterior cruciate ligament deficient subjects was significantly higher (mean 0.54 (SD, 0.04)) compared to healthy subjects (mean 0.25 (SD, 0.07)). CONCLUSIONS: Although the EMG-to-force processing model is not perfectly accurate, it is appropriate within a clinical context. RELEVANCE: Previous research supports the hypothesis that subjects with an anterior cruciate ligament deficiency compensate the loss of passive stability by developing higher co-activation levels of the knee muscles, i.e. active stabilization. Quantifying co-contraction may serve as a valuable parameter to evaluate clinical interventions and rehabilitation processes. The EMG-force model presented in this study appears to be a useful instrument for this purpose.     

Peak knee adduction moment during gait in anterior cruciate ligament reconstructed females

Background

Recent work has shown that anterior cruciate ligament reconstructed patients exhibit an increased peak knee adduction moment during walking gait compared to healthy controls. An increased peak knee adduction moment has been suggested to be a potential mechanism of degeneration for knee osteoarthritis. The few studies in this area have not considered an exclusively female anterior cruciate ligament reconstructed group. This study tested the hypothesis that female anterior cruciate ligament-reconstructed patients would have higher peak knee adduction moments than controls.

Methods

Peak knee adduction moment during walking was compared between a group of anterior cruciate ligament reconstructed females and a group of female activity matched controls over ten 15 m walking trials in a laboratory at a self-selected pace.

Findings

Peak knee adduction moment was lower for the anterior cruciate ligament reconstructed group (N = 17, M = 0.31 Nm/kg·m, SD = 0.08) than for the control group (N = 17, M = 0.41 Nm/kg·m, SD = 0.12; t(32) = 2.483, p = 0.010, one-tailed, eta squared effect size = 0.16).

Interpretation

A group of female anterior cruciate ligament reconstructed subjects did not exhibit a gait characteristic which has been suggested to be associated with knee osteoarthritis development and has been shown to be present in male and mixed sex anterior cruciate ligament reconstructed populations previously.     

Biomechanical evidence supporting a differential response to acute ACL injury

OBJECTIVE: To describe movement patterns in people with complete anterior cruciate ligament rupture objectively identified as good candidates for non-operative management of the injury. DESIGN: Involved side kinematics and kinetics were compared to the uninvolved side and to uninjured subjects. BACKGROUND: High-level athletes with anterior cruciate ligament rupture and poor dynamic stability (non-copers) have movement alterations, including less knee flexion and a decreased internal knee extensor moment during loading response, that are not seen in those with excellent knee stability (copers). Our screening exam can identify people with good rehabilitation potential for non-operative management of anterior cruciate ligament injury (potential copers), but the movement strategies of these individuals are unknown. METHODS: Sagittal plane kinematics and kinetics during the stance phase of walking and jogging were collected from 11 subjects who had an acute anterior cruciate ligament rupture and met the criteria of the screening exam, and were compared to 10 uninjured subjects, who we studied previously. Variables were those in which non-copers differed from uninjured subjects. RESULTS: The potential copers flexed their involved knee less than uninjured subjects and their uninvolved side during walking. Potential copers, compared to uninjured subjects, also had a lower vertical ground reaction force during loading response, a lower knee support moment, and an increased ankle support moment during walking. In jogging, the involved knee angle at initial contact was more extended compared to uninjured subjects, and the amount of knee flexion was less than the uninvolved side. No differences in kinetics were present during jogging. CONCLUSIONS: This study provides evidence that the potential copers identified by the screening examination have movement patterns that are consistent with people who have more knee stability than non-copers. RELEVANCE: Although potential copers have developed some characteristics of a successful stabilization strategy, the presence of kinematic alterations indicates that they may benefit from training programs designed to enhance dynamic knee stability.     

Muscular compensation and lesion of the anterior cruciate ligament: contribution of the soleus muscle during recovery from a forward fall

BACKGROUND: Knee stability following an anterior cruciate ligament lesion has been widely studied. Only recent studies focused on the contribution of the soleus muscle. Our purpose was to characterize the dynamic and muscular activity of balance recovery in healthy subjects and patients with an anterior cruciate ligament rupture. The role of the soleus was investigated in the ipsilateral compensation developed to stabilize the knee and in the contralateral compensation to recover balance. METHODS: Twelve anterior cruciate ligament deficient patients, ten anterior cruciate ligament repaired patients and 14 control subjects were recorded during a forward fall involving stepping to recover balance. FINDINGS: The dynamic of the centre of gravity remained normal when compared to the control group regardless of the treatment, suggesting an adapted compensation to knee instability in this situation. A bilateral increase in soleus activity was related to an increased duration in the balance recovery process in all patients. Patients used one of two strategies to recover balance regardless of the treatment: reducing the step length, involving an early recruitment of the soleus before heel contact, or anticipating braking with a similar step length requiring a predominant activity of the hamstrings. INTERPRETATIONS: These results suggest that bilateral activity of the soleus is involved to compensate for instability and highlight the contribution of the soleus to rehabilitation after an anterior cruciate ligament lesion, not only as a compensatory muscle acting at the knee level but also at a higher level in the bilateral control of stance.     

The effect of the walking speed on the stability of the anterior cruciate ligament deficient knee

BACKGROUND: The reasons behind the development of future pathology in individuals with anterior cruciate ligament deficiency are unknown. This is due to the lack of appropriate methods to assess functional dynamic knee stability. In this study, we investigated the effect of walking speed on the functional dynamic stability of the anterior cruciate ligament deficient knee. We defined functional dynamic stability as local stability or the sensitivity of the knee to small perturbations. The natural stride-to-stride variations that exist during locomotion reflect exactly the presence of these perturbations. We hypothesized that speed will affect local stability in the deficient knee, especially when compared with the contralateral intact. METHODS: Ten subjects with unilateral deficiency walked on a treadmill at their self-selected speed, 20% faster, and 20% slower, while kinematic data were collected (50 Hz) for 100 consecutive footfalls for each condition. The largest Lyapunov Exponent of the resulted knee joint flexion-extension time series was calculated to quantify local stability. FINDINGS: The deficient knee was significantly more locally unstable than the contralateral knee. Furthermore, increases in walking speed did not affect local stability for our subject population. INTERPRETATIONS: The altered local stability may render the deficient knee less adaptable to the ever-changing environmental demands. This may explain the increased future pathology found in these knees. However, future efforts should attempt to evaluate this speculation using longitudinal studies. We also propose that the tools utilized in this study can be used eventually to assess functional dynamic knee stability in clinical gait analysis.     

novel Award Second Prize Paper. Functional monitoring during rehabilitation following anterior cruciate ligament reconstruction.

OBJECTIVE: It was hypothesized that testing of ambulatory function and more demanding activities were more appropriate predictors of dynamic knee function before and after reconstruction of the anterior cruciate ligament than conventional measures of functional evaluation. It was assumed that assessment of dynamic plantar pressure distribution would represent a practical tool for guidance of the rehabilitation process after anterior cruciate ligament reconstruction. DESIGN: In a prospective study, 10 patients with isolated anterior cruciate deficiency were examined before and after replacement of the anterior cruciate (6, 12, 24 weeks) in a standardized technique. BACKGROUND: Today, functional assessment following anterior cruciate ligament reconstruction relies on clinical examination supplemented by instrumented testing of knee laxity and on isokinetic evaluation of muscle performance. Gait analysis has not been used as a quantitative measure of rehabilitation progress after surgery. METHODS: All patients were subjected to the same physiotherapy protocol. The clinical results were documented using the International Knee Documentation Committee (IKDC) protocol and the degree of knee laxity by an instrumented anterior drawer test. Muscular performance was evaluated by isokinetic testing. Dynamic pedography (EMED-SF 4) was performed to compare the non-injured and the operated leg during level walking and while descending stairs. RESULTS: Gait performance six weeks after surgery tended to be inferior to preoperative and late postoperative values. While the slight increase of maximum knee extensor torque in the operated leg and the improvement of the IKDC score during the rehabilitation period were not statistically significant, a significantly decreased gait asymmetry could be observed 12 weeks after surgery. The descending stairs test revealed functional deficits better than level walking. The latter test exhibited a strong correlation with the preoperative IKDC level and the maximum knee extensor deficit at 60 degrees /s. CONCLUSIONS: Dynamic pedography during level walking and while descending stairs is a valuable tool for monitoring the rehabilitation process after anterior cruciate ligament reconstruction. RELEVANCE: Due to the better resolution of functional deficits compared with indirect measures of function (isokinetic testing) assessment of the plantar pressure distribution may provide a more individualized adaptation for the rehabilitation program.     

Differences in normal and perturbed walking kinematics between male and female athletes

OBJECTIVE: To identify differences in lower extremity kinematic movement patterns between genders during walking through the application of an expected perturbation. DESIGN: Randomized limb kinematics were compared between healthy active males and females. BACKGROUND: Lower extremity kinematics during jump landing and cutting have been implicated as a potential source of the discrepancy in anterior cruciate ligament injury rates between genders. Kinematic differences between genders have been identified during tasks that are not provocative of anterior cruciate ligament injury but do result in increased ligament strain. Repetition of movement patterns that increase anterior cruciate ligament strain may increase the likelihood they will be reproduced during athletic tasks that produce force loads that exceed anterior cruciate ligament tensile strength. METHODS: Twenty subjects (10 women, 10 men) classified as a level I or II athlete underwent motion analyses while performing self-paced walking trials. Five trials were undisturbed, and five each with a platform translating either laterally or anteriorly at heel contact. Sagittal, frontal, and transverse hip angles as well as sagittal and frontal knee angles were collected during stance. RESULTS: Excursions in the frontal and transverse planes were greater at the hip and knee for females compared to males in each walking condition. The rate of these excursions also occurred more rapidly for females than males. There was no difference for joint angles at initial contact between genders, and there was no difference in the amount of sagittal plane excursion for the hip and knee when comparing genders. CONCLUSIONS: Females demonstrate characteristics during both normal and perturbed gait that may potentially contribute to increased anterior cruciate ligament strain. Repetition of these potentially harmful movement patterns during provocative athletic maneuvers may lead to anterior cruciate ligament injury. RELEVANCE: Females exhibit lower extremity kinematic patterns that differ from males. Female kinematic patterns may contribute to an increased risk for anterior cruciate ligament injury.     

Coordination stability between the legs is reduced after anterior cruciate ligament reconstruction

BackgroundThe study was designed to examine coordination differences in walking between individuals with an anterior cruciate ligament reconstruction compared with healthy matched controls. Predictions from the extended Haken, Kelso, and Bunz coupled oscillator model were tested in these populations.MethodsSeventeen persons with anterior cruciate ligament reconstruction and 17 matched controls participated in the study. Sagittal plane angular knee displacement was recorded using electrogoniometers over the lateral right and left knee joints while participants walked at five walking speeds overground. Coordination pattern and stability between the knees were quantified by mean and standard deviation of relative phase, respectively.FindingsMean relative phase was not influenced by walking speed or group. For both groups, coordination stability was maximal when individual's walked at their preferred gait speed. However, the anterior cruciate ligament reconstruction group demonstrated reduced coordination stability compared with healthy controls across the five speeds. Multiple regression analyses found that people with anterior cruciate ligament reconstruction who deviated more from antiphase coordination had decreased coordination stability.InterpretationAnterior cruciate ligament reconstruction results in decreased coordination stability, indicative of reduced coupling strength between the legs. This change in gait coordination, which has not previously been found in the literature, may contribute to the increased rate of re-injury and degeneration in individuals who have had this reconstructive surgery. Application of a motor control model enhances our understanding of the influence of an injury on coordination during gait.     

Examining outcomes from total knee arthroplasty and the relationship between quadriceps strength and knee function over time

BACKGROUND: Temporal-spatial gait parameters improve following total knee arthroplasty (TKA) but lower limb kinematics and moments fail to match those of age-matched healthy individuals. The aim of this study was to determine whether quadriceps strength, clinical measures of knee function, lower limb kinematics, and joint moments improve following arthroplasty and normalize over time. METHODS: Twelve patients underwent total knee arthroplasty were tested at 3 and 12 months following surgery. Twelve matched controls were also tested. All underwent quadriceps strength testing and gait analysis to calculate knee joint kinematics and kinetics. Function was assessed using clinical tests and self-report. FINDINGS: All clinical measures except for quadriceps strength significantly improved from 3 to 12 months. Gait asymmetry was observed at 3 months (lower stance times, peak knee flexion angle, range of motion and vertical ground reaction force), but ankle, knee and hip moments contributing to the total limb support moment were equivalent between legs. At 12 months, gait speed remained significantly slower than controls. Inter-limb differences in peak knee flexion angle and range of motion persisted. Greater hip and lower knee moments were evident in the operated limb, compared to the non-operated limb and controls. Quadriceps strength was positively correlated with faster times on the Time Up and Go and Stair Climbing Test and greater distances during the 6 Minute Walk test. INTERPRETATION: Patients who have undergone TKA demonstrate improvements in function as measured by self-report and functional performance measures. Gait becomes more symmetric and quadriceps strength becomes stronger. Some approached the values of healthy control subjects. Important differences still remain however. The larger hip extensor contribution to the total support moment may be to compensate for the diminished knee extensor contribution during level walking. Since instrumented gait analysis and functional performance measures appear to reflect different aspects of recovery following total knee replacement, both should be considered when evaluating gait and function.     

Benefit of isokinetic evaluations of knee before and after anterior cruciate ligament reconstruction in soccer players]

AIM: The aim of this study was to analyse the evolution of the isokinetic performance of the knee flexor and extensor muscles in soccer players before and after intra-articular anterior cruciate ligament reconstruction (Kennet-Jones). METHODS: Two isokinetic evaluations were carried out before surgery and after rehabilitation (i.e. 4 months later) in 18 soccer players. RESULTS: The initial evaluation showed that the stabilizing muscles of the knee were affected differently after lesion of the external anterior crossed ligament. At the opposite of the flexor muscles, the performance of the knee extensor muscles of the injured leg was significantly reduced as compared with that of the healthy leg (peak torque at 90 degrees /s, -16%; power at 180 degrees /s, -14%; total work at 240 degrees /s, -11%). Even if 4 months after surgery, this deficit was accentuated (peak torque at 90 degrees /s, -26%; power at 180 degrees /s, -23%; total work at 240 degrees /s, -19%), the preoperative results of the knee extensor muscle do not condition the postoperative performance. CONCLUSION: After a rupture of the external anterior crossed ligament, a regular program of isokinetic evaluation of the knee seems to be relevant in the follow-up of the wounded athlete. The evaluation before surgery can be used as reference, and from a psychological point of view, this evaluation can create confidence in the athlete during hospitalization. A second evaluation 4 months after surgery can be used to quantify the muscular deficit to direct the exercises of rehabilitation.     

The effect of total knee replacement on dynamic support of the body during walking and stair ascent

BACKGROUND: Little is known about the effects of total knee replacement surgery on the contributions of individual joint moments to the total support moment. A better understanding of these effects may enhance rehabilitation protocols and determine factors related to long-term surgical outcome. METHOD: Twenty-one subjects with total knee replacement and 21 controls performed level walking and stair ascent at two testing periods, pre- and 6 months post-surgery. Variables studied included gait velocity, stride length, knee flexion angle, net joint moments of the hip, knee and ankle, and total support moment. Data were analyzed at the first peak vertical ground reaction force. FINDINGS: For level walking, the total support moment, knee extensor moment, and knee flexion angle of total knee replacement patients were less than controls at post-surgery. For stair ascent, the patient group total support moment, ankle plantarflexor moment, and knee flexion angle were less than controls at both testing periods, while knee extensor moment was less than controls at post-surgery. Extensor synergies of the total knee replacement patients revealed less knee and more hip contributions during level walking and larger hip contributions during stair ascent to the total support moment than controls at both testing periods. INTERPRETATION: A feature of total knee replacement gait, pre- and post-surgery, is a stiff knee attitude which may serve to protect the quadriceps. The larger hip extensor contribution to the total support moment observed in the patients may compensate for the diminished knee extensor contribution during level walking and stair ascent.