Organization of postural responses following a rotational support surface perturbation, after TKA: sagittal plane rotations

Changes in Mediolateral Postural Control Mechanisms During Gait After Total Knee Arthroplasty

BACKGROUND

Patients who have total knee arthroplasty (TKA) likely suffer from decreased postural stability because of postoperative changes in musculoskeletal structure and loss of proprioception. The purpose of this experimental biomechanical study was to determine if patients who have TKA improve their dynamic postural control during walking after TKA as compared with before TKA. The secondary purpose was to assess changes in postural control between post-TKA patients and healthy controls.

METHODS

Twenty-three patients who had primary knee osteoarthritis scheduled to undergo unilateral or bilateral TKA were prospectively enrolled. Each patient was tested at 3 months, 6 months, and 12 months after TKA. Ten healthy controls matched for age, sex, and body mass index were selected from a database of previous healthy volunteers without knee osteoarthritis. Ten Vicon cameras and four AMTI force platforms were used to collect the marker and center of pressure (COP) data while participants performed gait.

RESULTS

Initial improvement in the double stance ratio was found by 6 months after TKA compared with before TKA. Patients showed improved postural control as evidenced by a faster mediolateral COP velocity and decreased double stance ratio at 12-month post-TKA compared with pre-TKA (P < .05). However, patients who underwent TKA exhibited limited ability to maintain consistent COP movement during walking with increased variability in COP parameters as compared with controls (P < .05).

CONCLUSION

Patients exhibited improvement in dynamic postural control after TKA with time, but had higher variability in COP parameters during gait than controls. It is possible that therapy aimed to improve proprioceptive balance after TKA may improve dynamic postural control.

A randomized controlled trial assessing the effects of preoperative strengthening plus balance training on balance and functional outcome up to 1 year following total knee replacement

PURPOSE

To investigate the effects of including balance training in a preoperative strengthening intervention on balance and functional outcomes in patients undergoing total knee replacement (TKR) and compare these effects to those induced by preoperative strengthening and no intervention.

METHODS

Eighty-two subjects scheduled for TKR were randomly allocated into the strengthening (ST, n = 28) group: a preoperative lower limb strengthening intervention; the strengthening + balance (ST + B, n = 28) group: same intervention augmented with balance training; and the control group (n = 26). The Berg Balance Scale (BBS) and the function in daily living subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS-ADL) were the primary outcomes. The secondary measures included balance and mobility, self-reported status, and knee function. The outcomes were assessed at baseline, 1 week before surgery, and 2, (primary endpoint), 6 and 52 weeks after surgery.

RESULTS

Compared with the controls, the participants in the ST and ST + B groups presented significant improvements from baseline to the end of the preoperative intervention in BBS (p = 0.005) and KOOS-ADL (p < 0.001). At 6 weeks post-surgery, the knee extensor strength values were similar in the two treatment groups and significantly higher than that in the controls. Overall, the participant outcomes in all groups stabilized at 1 year after surgery.

CONCLUSION

A preoperative strengthening intervention, regardless of whether it is complemented with balance training, enhances strength but not balance or functional outcomes at 6 weeks after surgery. Patients are expected to present similar performance at 1 year postoperatively, but adequately statistically powered trials are needed to confirm the findings.

LEVEL OF EVIDENCE

II.

TRIAL REGISTRATION

NCT02995668.

Kinematics following gait perturbation in adults with knee osteoarthritis: Scheduled versus not scheduled for knee arthroplasty

OBJECTIVE

To compare recovery kinematics following trip-simulated perturbation during gait between three groups: adults without knee Osteoarthritis (OA) and adults with OA, scheduled and not scheduled for Total Knee Replacement (TKR).

METHODS

People with OA scheduled for TKR (TKR group; N = 19) and not scheduled (NTKR group; N = 17) were age-matched with People without OA (N = 19). Outcome measures included: joint range of motion (ROM), Timed Up and Go (TUG), joint pain levels, Oxford score, Instrumental Activities of Daily Living Questionnaire, and the Activities-specific Balance Confidence Scale. Also, spatiotemporal gait parameters and joint kinematics were recorded during perturbed and unperturbed gait. The perturbed gait data were normalized by unperturbed gait data.

RESULTS

There were no differences between the two OA groups in the four questionnaire scores and joint ROM. The TUG score of the TKR group was higher than that of the NTKR group. There were no statistically significant between-group differences in the normalized spatiotemporal parameters. The OA groups showed statistically significant lower anterior pelvic tilt ranges and higher maximal hip adduction of the contralateral limb compared to the Non-OA group. When the contralateral limb was perturbed, the TKR group showed significantly lower pelvic rotation range compared to the NTKR and Non-OA groups. When the OA limb was perturbed, the maximal hip flexion of the injured limb was significantly lower and the maximal knee flexion higher in the OA groups compared with the Non-OA group.

CONCLUSION

The recovery strategy from trip-simulated perturbation of individuals with OA differs from that of individuals without OA. This may emphasize the importance of devising a treatment plan that focuses on improving balance and reactions to gait perturbation.

A comparison of balance-correcting responses induced with platform-translation and shoulder-pull perturbation methods

The understanding of reactive balance control mechanisms in humans emanates from studies utilizing a variety of perturbation methods, instructions, and sensory conditions. The use of different perturbation methods may produce method-specific balance-correcting responses. This study evaluated balance-correcting responses induced with platform-translation and shoulder-pull methods with equilibrated perturbation intensities, and whether the absence of vision affects balance-correcting responses differently between perturbation methods. Fifteen healthy young males participated. Unexpected forward and backward platform-translation and shoulder-pull perturbations were induced with eyes-open and eyes-closed. Participants were asked to behave naturally. Forward stepping trials were analyzed. Margin of stability (MOS) was calculated from the position data of reflective markers placed strategically around the body. MOS was reported at step onset and at foot contact. MOS was smaller at step onset (0.01 ± 0.01 m) and at foot contact (0.09 ± 0.01 m) during platform-translation trials and at both time points during shoulder-pull trials (0.04 ± 0.01 m and 0.17 ± 0.01 m, respectively). The absence of vision did not affect MOS at step onset. At foot contact during platform-translation with eyes-closed MOS was larger (0.11 ± 0.01 m) than with eyes-open (0.08 ± 0.01 m), but not different between eyes-open (0.17 ± 0.01 m) and eyes-closed (0.18 ± 0.01 m) during shoulder-pull. Participants required a second step to recover balance in 14% of the platform-translation and 3% of the shoulder-pull trials. During platform-translation trials participants demonstrated smaller MOS which placed them in a less favorable circumstance for balance recovery. Platform-translation appears to be more challenging than shoulder-pull perturbation in terms of balance recovery. This study underscores that caution is required when interpreting results of studies utilizing different perturbation paradigms.

Motor imagery training speeds up gait recovery and decreases the risk of falls in patients submitted to total knee arthroplasty

With Motor imagery (MI), movements are mentally rehearsed without overt actions; this procedure has been adopted in motor rehabilitation, primarily in brain-damaged patients. Here we rather tested the clinical potentials of MI in purely orthopaedic patients who, by definition, should maximally benefit of mental exercises because of their intact brain. To this end we studied the recovery of gait after total knee arthroplasty and evaluated whether MI combined with physiotherapy could speed up the recovery of gait and even limit the occurrence of future falls. We studied 48 patients at the beginning and by the end of the post-surgery residential rehabilitation program: half of them completed a specific MI training supported by computerized visual stimulation (experimental group); the other half performed a non-motoric cognitive training (control group). All patients also had standard physiotherapy. By the end of the rehabilitation, the experimental group showed a better recovery of gait and active knee flexion-extension movements, and less pain. The number of falls or near falls after surgery was significantly lower in the experimental group. These results show that MI can improve gait abilities and limit future falls in orthopaedic patients, without collateral risks and with limited costs.

Knee joint kinematics and neuromuscular responses in female athletes during and after multi-directional perturbations

The purpose of this study was to investigate weight-bearing knee joint kinematic and neuromuscular responses during lateral, posterior, rotational, and combination (simultaneous lateral, posterior, and rotational motions) perturbations and post-perturbations phases in 30° flexed-knee and straight-knee conditions. Thirteen healthy female athletes participated. Knee joint angles and muscle activity of vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus (ST), lateral gastrocnemius (LG), and medial gastrocnemius (MD) muscles were computed. Knee abducted during lateral perturbations, whereas it adducted during the other perturbations. It was internally rotated during flexed-knee and externally rotated during straight-knee perturbations and post-perturbations. VL and VM's mean and maximum activities during flexed-knee perturbations were greater than those of straight-knee condition. BF's mean activities were greater during flexed-knee perturbations compared with straight-knee condition, while its maximum activities observed during combination perturbations. ST's maximum activities during combination perturbations were greatest compared with the other perturbations. LG and MG's activities were greater during straight-knee conditions. Compared with the perturbation phase, the mean and maximum muscles' activities were significantly greater during post-perturbations. The time of onset of maximum muscle activity showed a distinctive pattern among the perturbations and phases. The perturbation direction is an important variable which induces individualized knee kinematic and neuromuscular response.

Clinical and Biomechanical Efficacies of Mechanical Perturbation Training After Anterior Cruciate Ligament Rupture

CONTEXT

Manual perturbation training improves knee functional performance and mitigates abnormal gait in patients with anterior cruciate ligament (ACL) rupture. However, manual perturbation training is time- and labor-intensive for therapists.

OBJECTIVE

To investigate whether perturbation training administered using a mechanical device can provide effects similar to manual training on clinical measures and knee biomechanics after ACL rupture.

DESIGN

Prospective cohort (therapeutic) study. A 2 × 2 analysis of variance was used for statistical analysis.

SETTING

A clinical and biomechanical laboratory.

PATIENTS

Eighteen level I/II patients with acute ACL ruptures participated in this preliminary study.

INTERVENTION

Nine patients received mechanical perturbation training on an automated mechanical device (mechanical group), and 9 patients received manual perturbation training (manual group).

OUTCOME MEASURES

Patients completed performance-based testing (quadriceps strength and single-legged hop tests), patient-reported questionnaires (Knee Outcome Survey-Activities of Daily Living Scale, Global Rating Score, and International Knee Documentation Committee 2000), and 3-dimensional gait analysis before (pretesting) and after (posttesting) training.

RESULTS

There was no significant group-by-time interaction found for all measures (P ≥ .18). Main effects of time were found for International Knee Documentation Committee 2000 (pretesting: 69.10 [10.95], posttesting: 75.14 [7.19]), knee excursion during weight-acceptance (pretesting: 16.01° [3.99°]; posttesting: 17.28° [3.99°]) and midstance (pretesting: 14.78° [4.13°]; posttesting: 16.92° [4.53°]) and external knee-flexion moment (pretesting: 0.43 [0.11] N m/kg/m; posttesting: 0.48 [0.11] N m/kg/m) (P ≤ .04). After accounting for pretesting groups' differences, the mechanical group scored significantly higher on triple hops (mechanical: 96.73% [6.65%]; manual: 84.97% [6.83%]) and 6-m timed hops (mechanical: 102.07% [9.50%]; manual: 91.21 [9.42%]) (P ≤ .047) compared with manual group.

CONCLUSION

The clinical significance of this study is the mechanical perturbation training produced effects similar to manual training, with both training methods were equally  effective at improving patients' perception of knee function and increasing knee excursion and external flexion moment during walking after acute ACL rupture. Mechanical perturbation training is a potential treatment to improve patients' functional and biomechanical outcomes after ACL rupture.

Comparing the effects of mechanical perturbation training with a compliant surface and manual perturbation training on joints kinematics after ACL-rupture

INTRODUCTION

Performing physical activities on a compliant surface alters joint kinematics and increases joints stiffness. However, the effect of compliant surface on joint kinematics after ACL-rupture is yet unknown.

AIM

To compare the effects of mechanical perturbation training with a compliant surface to manual perturbation training on joint kinematics after ACL-rupture.

METHODS

Sixteen level I/II athletes with ACL-rupture participated in this preliminary study. Eight patients received mechanical perturbation with compliant surface (Mechanical) and 8 patients received manual perturbation training (Manual). Patients completed standard gait analysis before (Pre) and after (Post) training.

RESULTS

Significant group-by-time interactions were found for knee flexion angle at initial contact (IC) and peak knee flexion (PKF) (p<0.004), with manual group significantly increased knee flexion angle at IC and PKF (p<0.03). Main effects of group were found for hip flexion angle at IC (Manual:34.34+3.51°, Mechanical:27.68+4.08°, p = 0.011), hip rotation angle at PKE (Manual:-3.40+4.78°, Mechanical:5.43+4.78°, p < 0.0001), and knee adduction angle at PKE (Manual:-2.00+2.23°, Mechanical:0.55+2.23°, p = 0.039). Main effects of time were found for hip adduction angle at PKE (Pre:6.98+4.48°, Post:8.41+4.91°, p = 0.04), knee adduction angle at IC (Pre:-2.90+3.50°, Post:-0.62+2.58°, p = 0.03), ankle adduction angle at IC (Pre:2.16+3.54, Post:3.8+3.68, p = 0.008), and ankle flexion angle at PKF (Pre:-4.55+2.77°, Post:-2.39+3.48°, p = 0.01).

DISCUSSION

Training on a compliant surface induces different effects on joint kinematics compared to manual perturbation training after ACL-rupture. Manual perturbation improved hip alignment and increased knee flexion angles, while mechanical training decreased knee flexion angles throughout the stance phase. Administering training on a compliant surface after ACL-rupture may help improving dynamic knee stability, however, long-term effects on knee health needs to be determined.

No difference between mechanical perturbation training with compliant surface and manual perturbation training on knee functional performance after ACL rupture

Manual perturbation training improves dynamic knee stability and functional performance after anterior cruciate ligament rupture (ACL-rupture). However, it is limited to static standing position and does not allow time-specific perturbations at different phase of functional activities. The purpose of this study was to investigate whether administering mechanical perturbation training including compliant surface provides effects similar to manual perturbation training on knee functional measures after an acute ACL-rupture. Sixteen level I/II athletes with ACL-ruptures participated in this preliminary study. Eight patients received mechanical (Mechanical) and eight subjects received manual perturbation training (Manual). All patients completed a functional testing (isometric quadriceps strength, single-legged hop tests) and patient-reported measures (Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS), Global Rating Score (GRS), International Knee Documentation Committee 2000 (IKDC 2000) at pre- and post-training. 2 × 2 ANOVA was used for data analysis. No significant group-by-time interactions were found for all measures (p > 0.18). Main effects of time were found for single hop (Pre-testing: 85.14% ± 21.07; Post-testing: 92.49% ± 17.55), triple hop (Pre-testing: 84.64% ± 14.17; Post-testing: 96.64% ± 11.14), KOS-ADLS (Pre-testing: 81.13% ± 11.12; Post-testing: 88.63% ± 12.63), GRS (Pre-testing: 68.63% ± 15.73; Post-testing: 78.81% ± 13.85), and IKDC 2000 (Pre-testing: 66.66% ± 9.85; Post-testing: 76.05% ± 14.62) (p < 0.032). Administering mechanical perturbation training using compliant surfaces induce effects similar to manual perturbation training on knee functional performance after acute ACL-rupture. The clinical significance is both modes of training improve patients' functional-performance and limb-to-limb movement symmetry, and enhancing the patients' self-reported of knee functional measures after ACL rupture. Mechanical perturbation that provides a compliant surface might be utilized as part of the ACL rehabilitation training. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1391-1397, 2018.

The effect of total knee arthroplasty on patients' balance and incidence of falls: a systematic review

PURPOSE

Despite the high incidence of falls in patients with OA, few studies have explored whether falls risk is affected after patients undergo total knee arthroplasty (TKA). Therefore, the aim of this systematic review was to identify the extent of the effects of TKA on balance and incidence of falls by critically reviewing the available literature.

METHODS

A systematic review of published literature sources was conducted up to March 2014. All studies assessing balance and incidence of falls after TKA (without physiotherapeutic intervention) were included. The methodological quality of each study was reviewed using the Critical Appraisal Skill Programme tool.

RESULTS

Thirteen studies were included, comprising of ten cohort studies (Level II) and three studies with Level of evidence III.

CONCLUSIONS

Findings provide evidence that TKA improves significantly single-limb standing balance (~60%) and dynamic balance up to 1-year following surgery (Level of evidence II). Moreover, TKA influences positively fear of falling and incidence of falls by switching 54.2 % of pre-operative fallers to post-operative non-fallers (Level of evidence II-III). It is highlighted that knee extension strength, proprioception and symmetrization of postural strategies have not fully recovered post-TKA and influence balance performance. Clinically, these persistent deficits need to be mitigated by physiotherapy even before TKA takes place.

Assessing Balance Function in Patients With Total Knee Arthroplasty

BACKGROUND

The Balance Evaluation Systems Test (BESTest) is a relatively new balance assessment tool. Recently, the Mini-BESTest and the Brief-BESTest, which are shortened versions of the BESTest, were developed.

OBJECTIVE

The purpose of this study was to estimate interrater and intrarater-interoccasion reliability, internal consistency, concurrent and convergent validity, and floor and ceiling effects of the 3 BESTests and other related measures, namely, the Berg Balance Scale (BBS), Functional Gait Assessment (FGA), and Activities-specific Balance Confidence (ABC) Scale, among patients with total knee arthroplasty (TKA).

DESIGN

This was an observational measurement study.

METHODS

To establish interrater reliability, the 3 BESTests were administered by 3 independent raters to 25 participants with TKA. Intrarater-interoccasion reliability was evaluated in 46 participants with TKA (including the 25 individuals who participated in the interrater reliability experiments) by repeating the 3 BESTests, BBS, and FGA within 1 week by the same rater. Internal consistency of each test also was assessed with Cronbach alpha. Validity was assessed in another 46 patients with TKA by correlating the 3 BESTests with BBS, FGA, and ABC. The floor and ceiling effects also were examined.

RESULTS

The 3 BESTests demonstrated excellent interrater reliability (intraclass correlation coefficient [ICC] [2,1]=.96-.99), intrarater-interoccasion reliability (ICC [2,1]=.92-.96), and internal consistency (Cronbach alpha=.96-.98). These values were comparable to those for the BBS and FGA. The 3 BESTests also showed moderate-to-strong correlations with the BBS, FGA, and ABC (r=.35-.81), thus demonstrating good concurrent and convergent validity. No significant floor and ceiling effects were observed, except for the BBS.

LIMITATIONS

The results are generalizable only to patients with TKA due to end-stage knee osteoarthritis.

CONCLUSIONS

The 3 BESTests have good reliability and validity for evaluating balance in people with TKA. The Brief-BESTest is the least time-consuming and may be more useful clinically.

Unipedal balance is affected by lower extremity joint arthroplasty procedure 1 year following surgery

Lower Extremity Joint Arthroplasty (LEJA) surgery is an effective way to alleviate painful osteoarthritis. Unfortunately, these surgeries do not normalize the loading asymmetry during the single leg stance phase of gait. Therefore, we examined single leg balance in 234 TJA patients (75 hips, 65 knees, 94 ankles) approximately 12 months following surgery. Patients passed if they maintained single leg balance for 10s with their eyes open. Patients one year following total hip arthroplasty (THA-63%) and total knee arthroplasty (TKA-69%) had similar pass rates compared to a total ankle arthroplasty (TAA-9%). Patients following THA and TKA exhibit better unilateral balance in comparison with TAA patients. It may be beneficial to include a rigorous proprioception and balance training program in TAA patients to optimize functional outcomes.

Functional outcomes of outpatient balance training following total knee replacement in patients with knee osteoarthritis: a randomized controlled trial

Objective:

To evaluate whether balance training after total knee replacement surgery improves functional outcomes and to determine whether postoperative balance is associated with mobility.

Design:

A prospective intervention study and randomized controlled trial with an intention-to-treat analysis.

Setting:

The rehabilitation center of a university-based teaching hospital.

Participants:

A total of 130 patients with knee osteoarthritis who had undergone total knee replacement surgery were recruited to attend an outpatient rehabilitation program. They were randomly allocated to additional balance rehabilitation and functional rehabilitation groups.

Interventions:

During the eight-week outpatient rehabilitation program, both groups received general functional training. Patients in the balance rehabilitation group received an additional balance-based rehabilitation program.

Primary outcome measures:

The functional reach test, single-leg stance test, 10-m walk test, Timed Up and Go Test, timed chair-stand test, stair-climb test, and Western Ontario and McMaster Universities Osteoarthritis Index were measured at baseline, eight weeks (T1), and 32 weeks (T2).

Results:

The balance rehabilitation group patients demonstrated significant improvement in the results of the functional reach test at T1 (37.6 ±7.8 cm) and T2 (39.3 ±9.7 cm) compared with the baseline assessment (11.5 ±2.9 cm) and Timed Up and Go Test at T1 (8.9 ±1.2 seconds) and T2 (8.0 ±1.9 seconds) compared with the baseline assessment (12.5 ±1.8 seconds). Moreover, the balance rehabilitation group patients exhibited significantly greater improvements in balance and mobility than did the functional rehabilitation group patients (all P < 0.001). Furthermore, improved balance was significantly associated with improved mobility at T2.

Conclusion:

Postoperative outpatient rehabilitation with balance training improves the balance, mobility, and functional outcomes in patients with knee osteoarthritis after total knee replacement.

Compensatory strategies for muscle weakness during stair ascent in subjects with total knee arthroplasty

Subjects with total knee arthroplasty (TKA) exhibit decreased quadriceps and hamstring strength. This may bring about greater relative effort or compensatory strategies to reduce knee joint moments in daily activities. To study gait and map out the resource capacity, knee muscle strength was assessed by maximal voluntary concentric contractions, and whole body kinematics and root mean square (RMS) electromyography (EMG) of vastus lateralis and semitendinosus were recorded during stair ascent in 23 unilateral TKA-subjects ~19 months post-operation, and in 23 healthy controls. Muscle strength and gait velocity were lower in the TKA group, but no significant group differences were found in RMS EMG or forward trunk lean. The results suggest that reduced walking velocity sufficiently compensated for reduced knee muscle strength.

The effect of ankle and knee immobilization on postural control during standing

BACKGROUND

This study examined the effects of ankle and knee joint immobilization on postural control in healthy young adults while standing.

METHODS

The 24 participants included in this study participated in postural standing tests under four different constraint conditions: free joints, ankle immobilization only, knee immobilization only, and ankle-knee immobilization. Tests were performed using a commercial balancing equipment (Biodex(TM), Inc., NY, USA) and software.

RESULTS

The overall limit-of-stability score and duration to completion of task were obtained at 75% limit-of-stability (moderate level of difficulty). The overall limit-of-stability score of free joints (34.5±9.1) were significantly different with the ankle immobilization only (26.0±11.6), and ankle-knee immobilization (26.4±7.4) conditions. The test duration increased in the following order: free joints (57.8±10.9), knee immobilization only (62.5±14.0), ankle immobilization only (68.0±14.9), and ankle-knee immobilization (69.4±17.7). The duration of the free joint condition greatly decreased than ankle immobilization only and ankle-knee immobilization conditions.

CONCLUSIONS

The ankle and knee joints have sufficient range of motion to prevent falls related to decrease postural stability due to insufficient range of motion or to improve postural stability.

Effects of balance training with visual feedback during mechanically unperturbed standing on postural corrective responses

Evidence of a non-specific effect of balance training on postural control mechanisms suggests that balance training during mechanically unperturbed standing may improve postural corrective responses following external perturbations. The purpose of the present study was to examine kinematics of the trunk as well as muscular activity of the lower leg and paraspinal muscles during postural responses to support-surface rotations after short-term balance training. Experiments were performed in control (n=10) and experimental (n=11) groups. The experimental group participated in the 3-day balance training program. During the training, participants stood on a force platform and were instructed to voluntarily shift their center of pressure in indicated directions as represented by a cursor on a monitor. Postural perturbation tests were executed before and after the training period: the slow and fast 10° dorsiflexions were induced at angular velocities of approximately 50°s(-1) and 200°s(-1), respectively. In the experimental group, the amplitude of the trunk displacements during slow and fast perturbations was up to 33.4% and 26.7% lower, respectively, following the training. The magnitude of the muscular activity was reduced in both the early and late components of the response. The kinematic parameters and muscular responses did not change in the control group. The results suggest that balance training during unperturbed standing has the potential to improve postural corrective responses to unexpected balance perturbation through (1) improved neuromuscular coordination of the involved muscles and (2) adaptive neural modifications on the spinal and cortical levels facilitated by voluntary activity.

On the role of knee joint in balance control and postural strategies: effects of total knee replacement in elderly subjects with knee osteoarthritis

This study aimed to evaluate the role of the knee joint in the neurosensory organization of balance control and the generation of postural sensorimotor strategies. Ten patients, aged over 60 years and having undergone unilateral total knee replacement (TKR) for osteoarthritis, and 20 controls were submitted to static and dynamic posturographic tests and to a sensory organization test (SOT) aiming at evaluating postural control in quiet stance and during movement. The patients were submitted to these evaluations after the disappearance of pain (TKR(1)) and at the end of a 6-week rehabilitation program (TKR(2)). Balance control being greatly improved at TKR2 compared to TKR1, the patients attain a quality of postural regulation similar to that of the controls; some postural abnormalities did however persist for the static test. Moreover, SOT values at TKR(2) close to those of the controls highlighted an improvement in motor response, better management in altered proprioceptive information situations, and greater use of the ankle to control balance. This model of intervention on the knee joint, namely knee replacement due to osteoarthritis, has shown that gradual functional sensorimotor restoration after TKR, due to intrasensory proprioceptive compensation either at knee, or at other joint levels (hip/ankle), improves dynamic balance control. This reacquisition allows the knee joint to recover its corrective compensatory role in postural regulation allowing, through neuroplasticity, the modification of muscular activation sequences and, thus, the implementation of anticipatory sensorimotor strategies.

A balance exercise program appears to improve function for patients with total knee arthroplasty: a randomized clinical trial

BACKGROUND

Patients with total knee arthroplasty (TKA) have impaired balance and movement control. Exercise interventions have not targeted these impairments in this population.

OBJECTIVES

The purposes of this study were: (1) to determine the feasibility of applying a balance exercise program in patients with TKA, (2) to investigate whether a functional training (FT) program supplemented with a balance exercise program (FT+B program) could improve physical function compared with an FT program alone in a small group of individuals with TKA, and (3) to test the methods and calculate sample size for a future randomized trial with a larger study sample.

DESIGN

This study was a double-blind, pilot randomized clinical trial.

SETTING

The study was conducted in the clinical laboratory of an academic center.

PARTICIPANTS

The participants were 43 individuals (30 female, 13 male; mean age=68 years, SD=8) who underwent TKA 2 to 6 months prior to the study.

INTERVENTIONS

The interventions were 6 weeks (12 sessions) of a supervised FT or FT+B program, followed by a 4-month home exercise program.

MEASUREMENTS

Feasibility measures included pain, stiffness, adherence, and attrition. The primary outcome measure was a battery of physical performance tests: self-selected gait speed, chair rise test, and single-leg stance time. Secondary outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index and the Lower Extremity Functional Scale.

RESULTS

Feasibility of the balance training in people with TKA was supported by high exercise adherence, a relatively low dropout rate, and no adverse events. Both groups demonstrated clinically important improvements in lower-extremity functional status. The degree of improvement seemed higher for gait speed, single-leg stance time, and stiffness in the FT+B group compared with the FT group.

LIMITATIONS

Due to the pilot nature of the study, differences between groups did not have adequate power to show statistical significance.

CONCLUSIONS

There is a need for conducting a larger randomized controlled trial to test the effectiveness of an FT+B program after TKA.

Functional performance with a single-radius femoral design total knee arthroplasty

BACKGROUND

Better muscular recovery of the extensor mechanism after TKA is claimed by femoral designs based on a sagittal single radius.

QUESTIONS/PURPOSES

We aimed to compare postoperative knee performance through the Knee Society scores, flexor and extensor muscle function, stability, and gait of a series of patients receiving a posterior stabilized, cemented TKA, with a single-radius femoral design.

METHODS

We compared a series of patients treated with a single-radius femoral design TKA to a simultaneous series of patients receiving a multiradius femoral design. Both groups were similar in demographics and preoperative Knee Society scores. The clinical pathways were identical. Outcome assessment included Knee Society scores, isokinetic assessment, stabilometry, and gait cycle analysis.

RESULTS

We observed higher functional Knee Society scores (86.6 +/- 1.89 versus 80.3 +/- 1.90), fewer physiotherapy sessions (19.9 +/- 4.65 versus 22.2 +/- 3.34), and less time with two crutches (3.5 +/- 1.2 versus 5.2 +/- 1.04 weeks) for patients receiving the single-radius design. Isokinetic evaluation showed decreased flexion peak torque (40.3 +/- 7.9 versus 48.7 +/- 9.6), increased extension peak torque (77.2 +/- 16.1 versus 69.1 +/- 14.4), and lower flexor/extensor ratio (0.5 +/- 0.08 versus 0.7 +/- 0.1) in patients with the single-radius design. Stabilometry showing less relative oscillation, and gait cycle indirectly confirmed better support in the limb with the single-radius design.

CONCLUSIONS

The studied single-radius femoral design showed better functional short-term outcome and better extensor performance.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The influence of knee rigidity on balance corrections: a comparison with responses of cerebellar ataxia patients

Knee rigidity due to aging or disease is associated with falls. A causal relationship between instability and knee rigidity has not been established. Here, we examined whether insufficient knee movement due to knee rigidity could underlie poor balance control in patients. We addressed this by examining the effect of artificially "locking" the knees on balance control in 18 healthy subjects, tested with and without individually fitted knee casts on both legs. Subjects were exposed to sudden rotations of a support surface in six different directions. The primary outcome measure was body centre of mass (COM) movement, and secondary outcome measures included biomechanical responses of the legs, pelvis and trunk. Knee casts caused increased backward COM movement for backward perturbations and decreased vertical COM movement for forward perturbations, and caused little change in lateral COM movement. At the ankles, dorsiflexion was reduced for backward perturbations. With knee casts, there was less uphill hip flexion and more downhill hip flexion. A major difference with knee casts was a reversed pelvis pitch movement and an increased forward trunk motion. These alterations in pitch movement strategies and COM displacements were similar to those we have observed previously in patients with knee rigidity, specifically those with spinocerebellar ataxia (SCA). Pelvis roll and uphill arm abduction were also increased with the casts. This roll movement strategy and minor changes in lateral COM movement were not similar to observations in patients. We conclude that artificial knee rigidity increases instability, as reflected by greater posterior COM displacement following support surface tilts. Healthy controls with knee casts used a pitch movement strategy similar to that of SCA patients to offset their lack of knee movement in regaining balance following multidirectional perturbations. This similarity suggests that reduced knee movements due to knee rigidity may contribute to sagittal plane postural instability in SCA patients and possibly in other patient groups. However in the roll plane, healthy controls rapidly compensate by adjusting arm movements and hip flexion to offset the effects of knee rigidity.

Postural responses following a rotational support surface perturbation, following knee joint replacement: frontal plane rotations

Total knee arthroplasty (TKA) is associated with altered sensory and motor functions of the knee which may impair balance control when standing and walking. This study examined the organization of electromyographic and kinematic postural responses to frontal plane support surface rotations, after TKA. Eight TKA patients and nine control participants volunteered. Patients demonstrated changes in onset latency of rectus femoris and gluteus medius, and in amplitude of muscle activity in tibialis anterior, gastrocnemius, rectus femoris, and gluteus medius, for both perturbation directions, and for both the surgical and sound limbs. Peak knee joint angular velocity was reduced among the patients for both perturbation directions and both the surgical and sound limbs, and patients demonstrated greater peak center of mass displacement. The CNS appears to alter the response to postural perturbation of both lower limbs, based on the reduced capacities of the surgical limb. Impaired detection of the valgus-varus loading of the knee joints may lead to the changes in muscle activity and resultant kinematics. Clinically, these findings are relevant in understanding that fully recovered TKA patients may continue to demonstrate balance impairments, and that balance training during physical rehabilitation may be advantageous to these patients.