Table 1 Balance and proprioception assessment

Brauner et al.

THA GROUP: 61 patients (F 27, M 34; mean age: 62 y)

HEALTHY CONTROL 38 healthy participants (16 F, 22 M; mean age: 47 y)

?

Dynamic stability was assessed using 2 pedal posture- pressure mats with a sensing surface (44X20cm) incorporating 220 capacitance-based, individually calibrated pressure sensors.

Participants were asked to stand with each foot on 1 of 2 pressure mats, a therapeutic chair was placed behind them, with sitting surface 30° tilted and height individually fixed so that to ensure that participants approached but did not exceed 90° hip flexion.

They were instructed to keep their arms outstretched and positioned horizontally in front of them with two fingers of each hand placed on a linear bearing. From the upright position subjects performed 2 sets of 5 squats, lowest position was reached when they perceived the chair. Participants performed exercises at their preferred movement velocity with 1 min rest between each exercise set.

13.2 days postoperatively (T1), then after 2 weeks rehabilitation period, 26.6 days postoperatively (T2).

At T1, unloading of the operated limb was 15.8% greater (P < .001) and anteroposterior and mediolateral centre of pressure root mean square values were 30 to 34% higher in patients who had undergone THA than in the healthy reference group (P < .05). Unloading was reduced by 12.8% toward a more equal distribution from T1 to T2 (P < .001). Although mediolateral stability improved between T1 and T2 (operated limb: 14.8%; P 0.024 non operated limb: 13.1%; P 0.015), anteroposterior stability was not significantly different.

Butler et al.

THA GROUP: 75 patients (F?, M?, mean age: 66.1 y)

TKA GROUP: 65 patients (F?, M?, mean age: 61.8 y)

TAA GROUP: 94 patients (F?, M?, mean age: 64.8 y)

?

Single leg balance was assessed using single-leg stance (SLS) time.

Participants were asked to maintain unilateral balance without assistance for 10 s on their surgical and non-surgical limbs while barefoot and with eyes open on a firm surface. Subjects allowed to move their upper extremities, but not to use they non-supportive limb for balance.

Twelve months after surgery.

THA group (63%) and TKA group (69%) had similar pass rates compared to TAA group (9%).

For the THA patients the SLS time on their surgical limb was 3.3 s while it was 5.3 s on their non-surgical limb. For the TKA patients the SLS time on their surgical limb was 4.4 s, while it was 5.7 s on their non-surgical limb. For TAA patients SLS time on their surgical limb was 3.2 s, while it was 6.3 s on their non-surgical limb.

Calò et al.

THA GROUP: 23 patients (F 13, M 10; mean age: 64.2 y)

HEALTHY CONTROL 20 healthy participants (10 F, 10 M; age matched with THR group)

THA with lateral approach

Postural control was assessed by means of dynamic posturography (Equi-Test Dynamic Posturography System by NeuroCom. Int. Inc., Clackamas, OR, USA)

Participants were asked to stand on a dual force-plate enclosed by a visual surround while performing a number of standing tasks based on quiet standing with eyes open and closed, with fix or moving back ground, responses to sudden translations or inclinations of the force platforms.

4 months after THR

No statistically significant differences were observed between patients and controls.

Chang et al.

23 patients (F 13, M 10; mean age 60 y)

THA with anterior, anterolateral or posterior approach.

Postural stability was assessed using a pressure measurement mat (RSscan International Co.,Belgium).

Balance was assessed using the Berg Balance Scale (BBS)

Balance confidence was assessed with the Activities-specific Balance Confidence Scale (ABC)

Functional reach test.

Participants were asked to stand barefoot with 4 ft placements: shoulder width stance (SWS), feet side-by-side stance (SSS), tandem stance with affected limb in the front (AFS), and tandem stance with non-affected limb in the front (SFS). They were instructed to stand as still as possible with both arms at their sides and eyes staring at a target 5 m away in front of them.

In each foot placement condition, three trials lasting 30 s were recorded with 15 s resting interval between trials.

The BBS is comprised of 14 tasks and is scored on a 5-point scale (0–4).

The ABC is a 16-item self-report measure of a person’s confidence in performing various activities of daily living without falling or experiencing a sense of unsteadiness.

One day before surgery, at 2 weeks, 6 weeks, 3 months, 6 months, and one year after surgery.

When the foot placement changes from shoulder width stance (SWS), side-by-side stance (SSS), and non-affected limb in the front stance (SFS) to affected limb in the front stance (AFS), the subjects tended to increase their postural sway after surgery and the progressive increment of CoP sway path length (CoPR). The CoPR had the greatest postural sway at the time of 2 weeks after surgery, but the CoP sway in ML direction (CoPML) at the time of 6 months after surgery. The descriptive data showed that the CoPR tended to decrease progressively after surgery. CoP sway in AP direction (CoPAP) peaked between6 months and 1 year after surgery, especially at the AFS and SFS position.

Berg balance test decreased significantly (p < 0.05) at 2 weeks and improved gradually, reaching the highest score of53.2 ± 1.9 at 6 months. The difference in functional reach test in all three directions was approaching significant level (p = 0.07–0.08). The descriptive data showed that functional reach distance tended to improve gradually after surgery, reached the maximum distance, and decreased at 1 year postoperatively.

Esbjornsson et al.

HIP OSTEOARTHRITIS GROUP: 28 patients (F 18, M 10; mean age 66.0 y)

HEALTHY CONTROL 21 healthy participants (F 13, M 8; mean age 66.2 y)

THA with an anterolateral approach.

The centre of mass trajectories was assessed using a 8 camera system (Vicon Motion Systems Ltd., Oxford, UK) and a conventional biomechanical model, the Plug-In-Gait full-body.

Participants were asked to rise from a seated position to a standing position as fast as possible five times consecutively, with the arms placed across their chest. The test was performed twice.

One month prior to THA and 1 year postoperatively.

Preoperatively patients in the hip osteoarthritis group displayed a larger contralateral shift (p < 0.001) and forward displacement of the centre of mass (p = 0.022) compared to control group. After surgery, deviations in both dimensions were reduced (medial-lateral p = 0.013; anterior-posterior p = 0.009), but the contralateral shift of the centre of mass remained larger (p = 0.010), indicative of persistent asymmetric limb loading.

Esposito et al.

THA ES group: 15 patients (mean age 68.7 y)

THA EF group: 15 patients (mean age 69.6 y)

THA procedure through a tissue sparing technique using a hybrid implant (uncemented cup and cemented stem

Two force platforms and an optoelectronic motion tracking system (SMART DX-700, BTS

Bioengineering, Milan, Italy), were used. CoP total

path and maximal excursion were evaluated in both medio-lateral (ML) and anterior – posterior (AP) planes. Shoulder and lower limbs loading were assessed.

Participants were asked to stand on a force platform in a comfortable position with the crutch positioned on the unaffected side, facing forward for 10 s, with elbow straight or elbow flexed.

At a mean of 4 ± 1 days after surgery

No significant differences between the two groups were found for postural stability parameters.

Shoulder load increased significantly in EF group compared to ES group. Leg loading symmetry was significantly reduced in the EF group.

Eyvazov et al.

28 patients with hip-spine syndrome (F 17, M 11; mean age 61.7 y)

THA with an anterolateral approach (cementless prosthesis)

Spinal sagittal alignment was assessed using anteroposterior and lateral standing X-rays.

Static balance was assessed using a 950–460 Bio Sway system (BIODEX Medical Systems, Inc. Shirley, NY, USA).

Patients were asked to stand in a comfortable position, with knee fully extended and arms slightly forward flexed while gazing forward. Patients were asked to stand in a comfortable position with knee fully extended and arms forward flexed and the following parameters were measured: PST – postural stability test (patient’s ability to maintain centre of balance), LOS – limits of stability test (the maximum angle patient can achieve from vertical without losing balance), CTSIB – clinical test of sensory integration of balance (objective measure for patient postural control on a static surface).

One month before surgery and 6 months after surgery.

No significant changes in sagittal alignment were observed postoperatively.

Median CTSIB improved from 1.22 (1.07, 1.45) to 1.01 (0.80, 1.19) and LOS from46.0 (42.0, 58.0) to 37.0 (32.0, 39.0) postoperatively.

Holnapy et al.

DIRECT-LATERAL (DL) EXPOSURE GROUP: (F 13, M 12; mean age 59.9 y 60.1 y respectively)

ANTERO-LATERAL (AL) EXPOSURE GROUP: (F 11, M 11; mean age 62.1 y 61.3 y respectively)

POSTERIOR (P) EXPOSURE GROUP: (F 12, M 13; mean age 60.8 y 61.2 y respectively)

CONTROL GROUP: (F 22, M 23; mean age 60.4 y 60.9 y respectively)

THA with traditional direct-lateral (DL) exposure with the joint capsule removed

THA with antero-lateral (AL) exposure with the joint capsule removed

THA with posterior (P) exposure with the joint capsule preserved

Dynamic balance was assessed using

Posturo Med (Haider-Bioswing GmbH, Weiden, Germany)

Subjects were asked to stand on the platform, a sudden unidirectional perturbation (medial and lateral direction in the horizontal plane) was given and the subjects had to balance on the moving platform to regain their equilibrium in the given position. In this case, the rigid plate performed damped free oscillation; the damping corresponded to the subject’s balancing ability.

The testing was performed in the sequence of standing on both limbs, standing on the non-affected limb (dominant limb for controls) and standing on the affected limb (non-dominant limb for controls). Each subject underwent 9 tests. Lehr’s damping ratio was calculated as the balancing capacity in response to a sudden unidirectional perturbation.

Prior to and at 6 weeks, 12 weeks and 6 months after THA.

In the case of direct-lateral and antero-lateral exposure, Lehr’s damping ratio significantly decreased compared to the preoperative values at 6 weeks postoperatively, but it increased steadily after-wards. Lehr’s damping ratio while standing on the affected limb was significantly lower – even at 6 months postoperatively – than that of the control group. In the case of posterior exposure (with the joint capsule preserved), Lehr’s damping ratio continuously increased in the postoperative period and corresponded to that of the control group at 6 months after total hip arthroplasty.

Hunter et al. 2020a

DIRECT ANTERIOR (DA) SURGICAL APPROACH GROUP: 61 patients (F?, M?; mean age 68.4 y)

DIRECT LATERAL (DL) SURGICAL APPROACH GROUP: 74 patients (F?, M?; mean age 69.4 y)

THA with direct anterior surgical approach

THA with direct lateral surgical approach

Activities-specific Balance Confidence Scale (ABC)

Future falls risk was assessed with the Falls Risk for Older People in a Community Setting (FROP-Com)

Dynamic balance was assessed with the Step Test.

The ABC is a 16-item self-report measure of a person’s confidence in performing various activities of daily living without falling or experiencing a sense of unsteadiness.

The FROP-Com is a multifactorial falls risk assessment consisting of 28 questions assessing 13 known falls risk factors.

Step Test: participants were instructed to stand with feet parallel, approximately 10 cm apart, with a step measuring 15 cm in height placed 5 cm in front of them. Participants placed their entire foot on the step and then back to the floor as rapidly as possible over 15 s. Each leg was tested separately and the total number of times the foot was placed on the step for each leg was recorded.

One year after THA

No statistically significant (p = .052) or clinically important difference for the ABC scale scores, though there was a small effect size of 0.34, 95% CI (−0.00, 0.68) in favour of DA approach.

No statistically significant (p = .055) or clinically important differences for the FROP-com while again there was a small effect size of 0.32, 95% CI (− 0.66, 0.02) in favour of the DA approach.

No statistically significant or clinically important difference for Step Test for least number of steps (p = .09), Step Test for non-surgical side (p = .15), Step Test for the THA side (p = .11). There were small effect sizes for these non-significant outcome measures in favour of the DA approach.

Hunter et al. 2020b

PATIENTS SUSTAINING at least 1 FALL AFTER THA (F 19, M 6; mean age: 71.6 y)

PATIENTS SUSTAINING NO FALL EPISODES (F 46, M 37; mean age: 72.7 y)

Direct anterior (47 patients); direct lateral (61 patients)

Activities-specific Balance Confidence Scale.

Each item of the Activities-specific Balance Confidence Scale is rated on a scale of 0 to 100%, with a score of 0 representing no confidence, whereas a score of 100 represents complete confidence. A summary score is calculated by adding responses on each item and dividing by the total number of items.

Twelve months after THR

ABC scale result was not a predictor of falls in the first year after surgery.

Jo et al.

FRACTURE GROUP: 16 patients (F 10, M 6; mean age: 66.6 y)

NON-FRACTURE GROUP: 15 patients (F 10, M 5; mean age: 64.6 y)

THR with posterior approach

Dyanamic balance was assessed using the Berg Balance Scale (BBS).

Proprioception was assessed using the joint position sense test (JPS).

The BBS is comprised of 14 tasks and is scored on a 5-point scale (0–4). The test takes about 20 min.

The JPS test measured the hip flexion accuracy of position replication in a supine position.

Three months after the surgery.

BBS scores of the non-fracture group were 44.06 ± 11.94 which was statistically higher than fracture group scores of 29.00 ± 17.73. However, there was no statistical significance in the JPS between the two groups. In the correlation between balance and other variables 3 months after the surgery, the BBS score and JPS were correlated.

Larkin et al.

TOTAL HIP RESURFACING: 16 patients (F 10, M 6; mean age: 66.6 y)

THA FEMORAL HEAD > 32 MM: 25 patients (F 12, M 13; mean age: 53.3 y)

THA FEMORAL HEAD ≤32 MM: 25 patients (F 13, M 12; mean age: 53.6 y)

CONTROL GROUP: 25 patients (F 3, M 22; mean age: 52.9 y)

?

Dynamic postural stability was assessed using a stabilometric force platform (PROPRIO 5000 machine, Perry Dynamics, Decatur, IL, USA)

Patients were placed on the platform with their feet shoulder width apart, knees slightly flexed, and center of mass centered over the center of the board by a single examiner. A 6-in. piece of rope was placed in the patients’ hands and they were instructed to hold this in front of them to remove the effect of the upper extremities on balance. An ultrasonic sensor was placed at the L5-S1 junction and this transmitted the patients’ position in space. After the double-limb testing was complete, three 1-min tests in each single-limb stance were performed with the side being tested first being randomly assigned. Each trial finished when one of the following criteria was met: 1 min had elapsed, the patient exceeded 3 in. of movement in 0.25 s, the patient moved greater than 5 in. from the starting point, the patient let go of the rope, the patient moved their feet, or the patient asked to stop.

Between 1 and 5 years after THA

Double-limb scores were not different among the four groups compared. With single-limb testing of the operative limb only considered, the total hip resurfacing arthroplasty group performed better than patients undergoing standard THA, and there was a trend for total hip resurfacing arthroplasty to perform better than the entire THA population but not better than large-head THA. However, when the operative limb was normalized against the nonoperative limb, the differences among groups were no longer significant.

Lavigne et al.

HIP RESURFACING GROUP: 24 patients (F 10, M 14; mean age: 49.6 y)

LARGE-DIAMETER HEAD THA GROUP: 24 patients (F 9, M 15; mean age: 49.8 y)

CONTROL GROUP: 14 patients (F 6, M 8; mean age: 44.4 y)

THA and HR with a posterior surgical approach and cementation of the femoral component.

Postural control was assessed using two embedded AMTI force platforms (Advanced Mechanical Technology Inc., Watertown, MA)

TUG test

Functional reach test.

Step test.

Subjects were asked to stand as still as possible with feet at shoulder width for 120 s on the force platforms recorded at 120 Hz the ground reaction forces and moments. The patients were asked to fix a target located 3 m in front of them at eye level.

For the timed up and go test, the patient had to rise from a standard arm chair, walk as fast as possible until he reached a stool placed 10 ft ahead of him, contour it, and come back to the chair and sit back.

During the functional reach test, the patient was standing still, shoulder flexed at 90°and the other arm on the side. We asked the patient to reach as far as possible ahead of him with his index finger without lifting the heels from the ground and the maximum distance reached (in centimetres) was measured with a ruler.

The step test consisted of five consecutive rises and descents from an 18-in. step (using the operated leg to climb up and keeping the same leg on the step when going down) that were performed as fast as possible. We recorded the time to accomplish this task.

Before surgery, 3, 6, and minimum 12 months

No difference was found preoperatively and at all follow-ups among HR, large-diameter head THA, and control subjects during the quiet standing test as shown by similar total path length of the COP in all groups.

There were no differences between the prosthesis groups for the timed up and go test.

We found differences between the two prostheses groups for only two tests: the functional reach and the step test at the advantage of patients undergoing HR and those undergoing large-diameter head THA, respectively.

The timed up and go test is the only functional test in which the control group surpassed the prostheses groups with a faster time at all evaluations compared with both study groups.

Lugade et al.

THA GROUP: 20 patients (F 6, M 14; mean age: 57 y)

HEALTHY CONTROL 10 healthy participants (F 5, M 5; mean age: 59.9 y)

All patients underwent primary THA using the anterior (12 patients) or lateral (eight patients) surgical approach on the affected limb and received uncemented (17 patients) or cemented (three patients) Zimmer hip implants

Dynamic balance control during gait was assessed using 3D Gait Analysis (Motion Analysis Corp, Santa Rosa, CA) and two force plates (Advanced Mechanical Technologies Inc., Watertown, MA).

Dynamic balance was assessed during gait using the CoM (centre of mass)-CoP (centre of pressure) inclination angles in the frontal and sagittal planes. Control subjects were tested for identical variables during two visits. During each visit, were asked to subjects to walk at a self-selected pace along a 10-m walkway. Were collected four level walking trials during each visit as subjects ambulated along the walkway.

Control subjects were tested during two visits 1 month apart to ensure test repeatability.

Pre-surgery, 6 weeks, and 16 weeks post-surgery

Patients having THA had improved gait and balance control by 16 weeks post-surgery. Patients undergoing THA had a smaller medial inclination angle with a greater posterior inclination angle 16 weeks post-surgery when compared with before surgery. The CoM velocity also increased for patients undergoing THA at maximum anterior and posterior CoM-CoP separation by 16 weeks post-surgery. However, at 6 weeks post-surgery, only the medial inclination angle improved from before surgery. When compared with the control subjects at 16 weeks post-surgery, patients undergoing THA performed similarly in gait but their CoM-CoP inclination angles in anterior and medial directions failed to reach control levels.

Majewski et al.

THA GROUP: 25 patients (F 11, M 14; mean age: 67 y)

HEALTHY CONTROL 50 healthy participants (age and gender matched)

THA with trans-gluteal approach

Balance in the form of trunk pitch (forwards-backwards) and roll (side-to-side) movements was assessed with the SwayStar balance system (Balance International

Innovations GmbH)

Participants were asked to perform quiet stance, gait, gait over barriers, stairs and sit-to-stand tasks.

Before surgery and at 4 and 12

months after surgery

There was a progressive improvement at 4 and 12 months for gait and sit-to-stand tasks parameters. By 12 months, the values approached those of the control group.

Trunk pitch (forwards-backwards) and roll (side-to-side) velocities were less stable when walking over barriers as was roll for the sit-to-stand task, indicative of a residual deficit of balance in THA patients.

Merle et al.

14 patients (F 6, M 8; mean age between 57 and 85 y)

THA with postero-exterior (11) and anterior (3) approach

Quiet standing over a dual force platform (PF02 Equi+,

Aix-les-Bains, France). The center

of pressure displacement was recorded separately under each limb.

Participants were instructed to remain as stable as possible in a standardized upright position in two conditions: spontaneous, i.e. no instructions as to how to distribute the body weight, and imposed, i.e. instructions to load the body weight on the operated limb.

12 ± 3 days after

surgery

In the SPO condition, the operated limb was less loaded than the healthy limb. In the IMP condition load distribution was close to symmetry. Greater displacements along the ML axis

was found for the trajectories measured under the healthy limb than under the operated limb.

Nantel et al.

SURFACE REPLACEMENT ARTHROPLASTY (SRA) GROUP: 10 patients (F 4, M 6; mean age: 43.1 y)

TOTAL HIP ARTHROPLASTY (THA) GROUP: 10 patients (F 5, M 5; mean age: 51.1 y)

CONTROL GROUP: 10 patients (F 4, M 6; mean age: 45.1 y)

THA and SRA with a posterior surgical approach and uncemented prosthesis.

Postural balance was assessed using a force platform AMTI force plate (Advance Mechanical Technology Inc., MA, USA).

All participants were asked to perform two postural tasks. For the first task, patients were requested to maintain a quiet standing posture on the force platform, with eyes open and feet at shoulder width for 120 s. For the second task, patients had to maintain a one leg stance position for 10 s. The operated leg was tested twice with an inter-trial resting period of 30 s.

Six months after surgery

During static dual stance, the statistical analyses revealed significantly larger Root-Mean-Square and RMS_COM - Root-mean-square (RMS) of the center of pressure (COP)- amplitude in the medial–lateral direction for THA subjects compared to SRA and control subjects.

Statistical analysis showed significant dependence between groups and one leg stance completion (P = 0.01). Five of the ten patients in the THA group did not complete the task compared to one for the SRA subject. In the control group all subjects completed the task

Nantel et al.

SURFACE REPLACEMENT ARTHROPLASTY (SRA) GROUP: 14 patients (F 5, M 9; mean age: 45.0 y)

LARGE-DIAMETER HEAD TOTAL HIP ARTHROPLASTY (LDH THA) GROUP: 14 patients (F 3, M 11; mean age 50.8 y)

CONTROL GROUP: 14 patients (F 6, M 8; mean age 44.5 y)

LDH-THA and SRA with a posterior surgical approach and uncemented prosthesis.

Postural balance was assessed using a force platform AMTI force plate (Advance Mechanical Technology Inc., MA, USA)

Each participant had to achieve 2 postural tasks. The first task consisted of quiet standing for 120 s with eyes open. In the second task, patients had to hold a one-leg stance position on the operated limb for 10 s. The operated leg was tested twice with a sufficient intertrial resting period. This task was considered successful when the patient was able to stay still on 1 leg for 10 s and was considered unsuccessful if the patient had to touch the ground with the contralateral foot.

Between 5 and 7 months

The statistical analyses for the dual stance task revealed significantly lower larger Root-Mean-Square_COP amplitudes in the medial-lateral direction for large diameter head THA and SRA subjects compared to control subjects. No significant differences between groups in the anterior-posterior direction for both RMS_COP R Root-mean-square (RMS) of the center of pressure (COP)- RMS_COM -Root-mean-square (RMS) of the center of mass (COM)- and RMS _COM amplitudes.

There was no significant difference in the ability to complete the one-leg stance task between the 3 groups.

Ninomiya et al.

THA GROUP: 58 patients (F 48, M 10; mean age: 68)

CONTROL GROUP: 46 patients (F 38, M 10; mean age: 69.9)

Antero-lateral operative procedure

Single-limb stance time.

Fall Rate.

Single-limb stance time was measured with subjects in a standing posture with both hands on the hips, starting at the time when one foot was lifted from the floor from the standing position. The evaluation was stopped when 1) the support leg shifted from the floor, 2) the lifted leg touched the floor, 3) the lifted leg came in contact with the support leg, or 4) 60 s was reached.

The fall rate was surveyed by asking participants if they had fallen in the past year. Falls were defined as “a person falling onto the same level or a lower level on their own, with no external force from another person, loss of consciousness, paralysis from a sudden attack such as stroke, or an epileptic seizure.

Ten years after THA

THA patients had 42.1% shorter single-leg stance time on the operated side and 2.8 times higher fall rate.

Pop et al.

THA GROUP: 55 patients (F 31, M 24; mean age: 56 y)

HEALTHY CONTROL 48 healthy participants (F 31, M 17; mean age: 58 y)

THA with a lateral approach and uncemented prosthesis.

Static balance was assessed using a stabilometric force platform (Alfa, AC International East, Poland).

Subjects were asked to stand barefoot on the force platform in a comfortable, self-chosen, double-leg stance position, with their arms alongside the body. They were instructed to stand as still as possible during the tests and to breathe normally. Data were collected in both visual conditions (eyes opened and eyes closed) in random order. During the test with opened eyes, subjects were asked to look straight ahead at a visual reference point. Each test lasted 30 s, followed by 30 s of rest interval.

Between 24 and 36 months after THR

In the eyes-open condition, COP mean velocity in ML direction was significantly higher in THR compared to controls. In the eyes-closed condition, COP mean velocity in AP and ML direction and COP path length were significantly higher in THR compared to controls. In both groups COP mean velocity in AP and ML direction, and COP path length and area were higher in the closed-eyes compared to the open-eyes condition. THR males had higher COP mean velocity in AP and ML direction, and COP path length than male controls, while no between-groups differences were found for females.

Quagliarella et al.

EXPERIMENTAL GROUP: 181 patients divided into THA and TKA group (F 118, M 63). THA 81 patients pre-operatively (mean age: 64.1 y), THA 20 patients at 6 months (mean age: 62.9 y), THA 14 patients at 12 months (mean age: 66.6 y)

CONTROL GROUP: 59 patients (F 24, M 35; mean age: 67.4 y)

?

Static balance was assessed using orthostatic posturography (Kistler Instrumente AG Winterthur, Switzerland).

Participants were asked to stand barefoot on the force platform facing in the anterior-posterior (AP) direction, in a comfortable self-chosen stance, with their arms hanging down beside the body.

Each subject carried out one test with eyes open and one with eyes closed, to evaluate the Romberg ratio. During the eyes open trial, subjects were asked to look straight ahead at a visual reference point (a red dot 3 cm in diameter, located 2 m away on the wall, at eyes height). Between trials, subjects could rest in a chair for approximately 2 min.

Prior to surgery, after 6 months and after 12 months.

No statistically significant differences (SSD) due to age were found in the Posturographic Parameters (PPs) after subdividing the CG and the EGs (for each trial session) into two subgroups (under/over 60 years. The assessment with closed eyes evidenced more SSD among the two EGs and the CG than the test with open eyes. Preoperatively SA (sway area), MV (mean velocity of the CoP), RMSD (as resultant and in the CoP AP and ML directions) in particular in the ML direction, and PF95_AP (that estimates the frequency extent of the CoP time series) were higher in THA than in the CG. During the follow-up only in the THA group was there a steady reduction toward normal values in RMSD_RD (the vector of distances from the mean CoP to each of its points), RMSD_AP and SA, whereas the variations between sessions of the other PPs did not present a clear trend.

Queen et al.

THA female group (n: 57; mean age 57.7 y)

THA male group (n: 70; mean age 52.7 y)

?

Static balance was assessed with a 10 s single-limb stance task

Dynamic balance was assessed with the Lower Quarter Y-Balance

Test

Patients were asked to stand on a single limb for 10 s. Values were treated as binary with success being greater than 10 s and failure being less than 10 s.

For the YBT-LQ, the participant was instructed to remain in unilateral stance on the stance platform while pushing the reach indicator in three independent directions (Anterior, Postero-medial, and Postero-lateral)

At least 1 year following surgery

Women failed single-leg stance at a higher rate than men. Reach distance was different between limbs for all reach directions with greater reach distance on the nonoperative limb for all patients. Men had a greater reach distance in the ANT and PM directions.

Rasch et al.

THA group: 22 patients (F 18, M 4; mean age 67 y)

THA with 2 types of hip prostheses: a cementless porous-coated femur stem (n = 8) and a cemented polished and tapered femur stem

(n = 12).

Assessment of postural stability

with a force plate (MuscleLab; Ergotest, Langesund, Norway).

The patients were told to stand still on the force plate with a gap of 20 cm between the feet. 6 measurements of bilateral standing with alternating open or closed eyes were first conducted, followed by 6 measurements standing on 1 ft—alternating OA and healthy limb—with eyes open.

The day before surgery, and 6 months and 2 years after THA.

Sway measurement of unilateral standing before and after operation showed no statistically significant differences between OA limbs and healthy limbs except for the 6-month follow-up of sagittal sway, where it was greater in the OA limb (p = 0.02). Measurement of bilateral standing showed a reduced lateral and sagittal sway postoperatively compared to preoperatively, although this was only statistically significant with eyes closed (p = 0.006). The sagittal sway was more pronounced than the lateral sway in both OA and healthy limbs, both preoperatively and postoperatively.

Rougier et al.

THA GROUP: 14 patients (F 6, M 8; mean age between 57 and 85 y)

CONTROL GROUP: 13 patients (F 10, M 3; mean age between 69 and 95 y)

THA with posterolateral (10) and anterior (4) approach

Standing balance on a double force platform (PF02, Equi+, Aix les

Bains, France).

The subjects stood barefoot on a double force platform with eyes closed. Control group participants were required to adopt an asymmetrical body weight distribution close to that observed on average for the patients.

The center-of-pressure (CP) and the center-of-gravity (CG) movements were analysed for each limb.

12 days after surgery

Patient with THA showed greater movements for both plantar and resultant CP displacements, principally along the antero-posterior (AP) axis, a decreased contribution of the hip mechanisms in the production of CP displacements along the medio-lateral (ML) axis, greater resultant CP and CG movements along the AP axis and increased differences between CP and CG along both ML and AP axes.

Sliwinski et al.

THR GROUP: 16 patients (M 7, F 9; mean age 70.9 y)

HEALTY CONTROL: 16 healthy participants

(M 5, F 11; mean age 74 y)

THA (16 participants had cemented procedures and 2 had non-cemented)

Dynamic stability (the vertical projection of the centre of mass -COM- to the base of support -BOS) n the medial–lateral direction during walking was evaluated with a VICON 370 system and workstation software.

27 spherical retro reflective markers (2.5 cm in diameter) were affixed to the participant’s skin using adhesive tape to the following land marks (1), forehead (2), chin (3), right and left acromion processes (4), right and left lateral epicondyles of the humerus (5), right and left wrist midpoints (6), right and left third metacarpal phalangeal joints (7), sacrum (8), right and left ASISs (9), right and left greater trochanters (10), right and left femoral wand markers (11), right and left lateral knee joints (12), right and left calf wand markers (13), right and left lateral malleoli (14), right and left calcanei (15), and right and left second metatarsal phalangeal joints. Heel switches were affixed to the bottom of the heels of each shoe to assist in data processing of heel strike and toe off identification for temporal–spatial analysis. Participants were instructed to wear their customary walking shoes and to walk as they would normally at their typical walking speed

All measurements were obtained in a single session. The patients were a minimum of 2 months post-surgery (Ten of the THA participants were 2–3 months post-surgery, and one each 5, 6 and 7 months, and one 2 years post-surgery).

No significant difference was identified during single-limb-support phase for within and between group comparisons. During each leading limb condition, for the healthy older adults, the vertical projection of the COM during double-limb-support was held on average laterally (2% lean to the right, and 4% lean to the left) towards the leading limb side. The absolute difference score for DLS dynamic stability was larger for the healthy older adults (5.7 ± 2.5%) in comparison to the individuals with THA (1.7 ± 0.74%). The individuals with THA held their COM on average toward their operated limb (operated 54.2 ± 4.7%, non-operated 52.3 ± 5.0%) during both limb lead conditions as the COM location was greater than 50%.

Walking velocity was slower with individuals with THA (1.09 ± 0.19 m/s) compared to healthy older adults (1.25 ± 0.15 m/s).

Szymansky et al.

THR GROUP: 20 patients (F 10, M 10; mean age 61,2 y)

RESURFACING GROUP: 20 patients (F 8 M 12; mean age 54,1 y)

CONTROL GROUP: 20 subjects (F 10, M 10; mean age 31,2 y)

Hip resurfacing implantation with posterolateral approach and total hip replacement cementless stem

Balance was evaluated with a force platform (QFP Système, Medicapteurs, Nice, France)

During measurement, the subject was standing at ease, arm along the body and feet in 30° external rotation in line with AFP standard 85. The subject was to focus on a point 3.5 m in front of him or her, and remain standing for 25.6 s, followed by 25.6 s focusing on the point in monopedal weight-bearing on the operated side and then on the contralateral (healthy) side for 25.6 s; the contralateral healthy side served as reference for all measurements. In the healthy control group, the same three tests were performed, with bipedal and left and right monopedal weight-bearing. An observer stood at either side of the subject to guard against any fall.

The two cohorts which underwent surgery were evaluated in one occasion post op at 15.5 ± 2.3 months -range, 12–20 months- the THR group had a mean follow-up of 15.3 ± 2.6 months).

Balance analysis on both legs found comparable results in the control and resurfacing groups. The weight-bearing both leg balance area was greater in the hip replacement than in either of the other two groups (p < 0.05), and five times greater than in the resurfacing group (p < 0.05). The single leg weight-bearing balance results were significantly better in the resurfacing group, with a balance area half that of the hip replacement group, whether on the operated or the non-operated side (p < 0.001). In all groups, the difference between left and right monopedal stance was non-significant.

Talis et al.

THE GROUP: 27 patients (F 20 M 7; mean age 56 y)

HEALTHY CONTROL: 27 healthy participants (F 18, M 9; mean age 55 y)

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Balance was assessed with the use of two force platforms measured vertical forces under each foot during quiet standing and sit-to-stand manoeuvre.

During quiet standing (barefoot) the feet of the subject were placed on separate stabiloplatforms, with the heels spaced 10 cm apart. Thus, the bilateral loadings were measured directly and independent of the varus/valgus moments. Subjects were instructed to stand naturally for 40 s with their arms at their sides: 20 s with eyes open (EO) and 20 s with eyes closed (EC).

Subjects were seated on an armless chair (without a back support) whose height was adjusted to keep the thigh horizontal. The feet were placed on separate force plates, with the heels spaced 10 cm apart being the same as in the quiet standing task. Subjects were instructed to rise from a chair as they would usually do except without using the arms. An acoustic tone served as a trigger (‘go’) signal to stand up. Subjects (barefoot) executed this movement at natural speed with eyes open (EO), as fast as possible (fast) and at natural speed with eyes closed (EC) (three trials in each condition).

Mean time after surgery 19 months (between 2 months and 2.8 years)

In all tasks patients tended to preferentially load the non-operated limb, though the amount of asymmetry depended on the task being most prominent during standing up (inter-limb weight bearing difference exceeded 20%, independent of speed or visual conditions). In contrast, when performing quiet standing, the inter-limb difference was typically less than 10%.

Visual information seems to play only a minor role in the control of the weight-bearing ability.

Temporiti et al.

GROUP BILATERAL THA: 20 patients (F 2, M18; mean age 51.6 y)

GROUP UNILATERAL THA: 20 patient (F 6, M 14; mean age 53.1 y)

One stage bilateral or unilateral THA.

Postural tasks were recorded with an eight-camera optoelectronic system (SMART DX, BTS, Italy) synchronized with two force platforms (P-6000, BTS, Italy).

Timed Up and Go (TUG), Body Weight Distribution Symmetry Index (BWDSI) during stand-to-sit (STS).

TUG: Patients were asked to rise from an armchair, walk at a comfortable pace for three meters, turn and walk back to the chair and sit down again.

Postural tasks: Three retro-reflective markers were placed on the two acromial angles and on the seventh cervical vertebra to detect their motion with the optoelectronic system. The following tasks were recorded:

1) Standing - patients were asked to stand barefoot in standing position with their arms crossed over their chest (feet were positioned parallel on two adjacent force platforms with heels at 10 cm apart and equidistant from the medial edge). Study participants were asked to maintain the standing position for 60 s with eyes open (EO) while looking at a fixed point placed in front of them at two meters distance. After resting for 5 min, the same test was executed with eyes closed (EC).

2) Stand-to-Sit - patients were seated on an adjustable-height chair with back support, with knees flexed at 100° (feet placed parallel on two adjacent force platforms with heels at 20 cm and equidistant from the medial edges). Patients were asked to stand up and, after 10 s, they were asked to sit down with their arm across their chest returning to the same initial position. Only the stand-to-sit component of the task (STS) was processed due to the inability of several participants to rise from the chair without using their arms.

Before surgery, at three and seven days after.

No between-group differences were found for TUG. BWDSI during STS and standing revealed differences over time in favour of patients with bilateral THA, who showed better symmetry in weight distribution. Shorter CoP path length was observed during standing in patients with unilateral THA, who mainly used their non-affected limb to maintain balance.

Ulivi et al.

DIRECT SUPERIOR APPROACH: 22 patients (F 15, M 7; mean age 74 y)

POSTEROLATERAL APPROACH: 23 patients (F 13, M 10; mean age 72 y)

The risk of falls was assessed by means of the Brief-BESTest

Timed Up and Go (TUG)

Brief-BESTest: 36 items grouped into 6 specific postural control systems: biomechanical constraints, stability limits and verticality, anticipatory postural adjustments, postural responses to external perturbations, sensory orientation during stance, and stability in gait.

TUG: Patients were asked to rise from an armchair, walk at a comfortable pace for three meters, turn and walk back to the chair and sit down again.

Before (PRE), 1 month (T1) and 3 months after (T3) surgery

Patients with DSA had a lower risk of falls at T3 compared with T1 and higher TUG scores at T3 compared with T1 and PRE. Furthermore, PL showed a lower risk of falls at T3 compared with T1 and PRE while TUG did not show any statistically significant difference

Van Driessche et al.

THA GROUP: 44 patients divided into:

- posterior approach (F 7, M 7; mean age: 70.9 y)

- anterior approach (F 8, M 7; mean age: 69.3 y)

- Rottinger approach (F 7, M 8; mean age: 69.3 y)

CONTROL GROUP: 26 asymptomatic subjects (F 20, M 6; mean age: 66.6 y)

Static balance was assessed on a stabilometric platform AMTI AccuGait TM 50 Hz (AMTI, Watertown, MA, USA)

Participants performed two single-leg stance tests (left followed by right leg stance). Center of pressure displacement was analysed.

Within 2 months after surgery

No significant differences between approaches were found for fulfilment of the postural task. Subjects operated on with the anterior or Röttinger approach showed higher average CP displacement speed and path length than asymptomatic subjects. Subjects operated on through the posterior approach showed no significant differences from asymptomatic subjects.

Wang et al.

THR GROUP: 20 patients (F 7, M 13; mean age 48 y)

HRA GROUP: 20 patients (F 11, M 9; mean age 46 y)

Each surgery was performed through

a posterolateral surgical approach

by the same surgical team.

Hip joint position sense (JPS) was tested using Active-active method in supine position.

Patients were placed in a supine position and blindfolded to eliminate visual cues. The test started at neutral position (0°) and patient actively flexed the hip toward the flexion target position of 45°, which was indicated by a mechanical obstruction. After holding that position for 5 s, patient focused and remembered the angle, and brought the joint actively back to the neutral starting position. Then, patient was asked to actively reproduce the target position without the mechanical obstruction and hold at where he/she felt it was the just position. Five repetitions were performed for each leg and “absolute angular error” values were obtained from the start and stop angles.

Preoperatively, postoperative 6, 12,

24 and 36 months.

Both groups of patients had

similar absolute angle error preoperatively and decreased absolute angle error. The THA group had higher mean absolute angle error than that of HRA group at postoperative 6 month and 12 months, thereafter, both groups had similar absolute angle error. During the follow up, a tendency towards decreased absolute angle error from 6 month to 36 months was witnessed in both groups. Especially between 6 month and 12 month and between 12 month and 24 months, there were significant differences in absolute angle error. After one year, both group of patients had stable absolute angle error.

Warenckack et al. 2020

THR GROUP: 30 patients. (F 25, M 5; mean age 69.4 y)

CONTROL GROUP: 30 participants (F 25, M 5; mean age 68.8 y)

THR with anterolateral approach

Dynamic balance and functional mobility were assessed with Metitur’s Good Balance force platform.

Timed Up and Go test, 3 m walk test, Functional Reach Test, 30s Chair Stand

Test, Step Test and Berg Balance Scale.

Dynamic test on force platform. The dynamic test on the force platform was based on the principle of biofeedback. It was performed on 1 board (including “path”) and with different sensitivity of platform (B100 and B60). The board showed “paths” for displacement of centre of feet pressure. Patients could observe certain position of the centre of feet pressure (COP) on the screen. It was visualized as a cursor and the tasks were to achieve the targets successively displayed on the screen during displacement of the body. The subject’s position during dynamic tests was upright with feet placed parallel and 20 cm apart. TUG: During the test, patients were to rise from a chair, walk a distance of 3 m, make a turn of 180 ° having crossed a designated line and return to the chair. Recording the time of performing the task was initiated by the “start” command and stopped the moment a patient returned to the sitting position with the back resting against the chair. Patients were instructed to do the task as quickly as possible, but at the maximum speed at which the patient could walk safely without running Each participant completed three trials. 3 m walk test: Patients were instructed to stand with their toes touching the start line and walk fast beyond the taped finish line. The time from the moment their foot crossed the start line to the moment their both feet crossed the stop line was measured. Each participant completed three trials. Functional reach test: During test, the patient was standing by the wall with their feet shoulder-width apart,one shoulder flexed at 90° and the other arm on the side. A ruler was attached to the wall. Patients were instructed to reach their maximal distance (in centimetres) without moving their feet or losing balance and come back to the standing position. If subjects raised a heel or took a step during testing; the trial was repeated. Each participant completed three trials. 30s Chair Stand Test: The test consists of standing up and sitting down from a chair as many times as possible within 30 s. Initially, subjects were seated on the chair with their arms folded across the chest and with a back in an upright position. They performed only one trial and started it after a command. A standard chair with armrests was used. The step test: When tested, subjects were instructed to place one foot onto a 7.5 cm high step and then take it back down to the floor repeatedly as fast as possible. The score is the number of steps completed in the 15-s period for each lower extremity. Both sides were tested two times, with the THR group completing the test first with the operated leg (ST O) and then the non operated leg (ST N). BBS: Subjects did 14 different tasks including static tests with different feet positions and functional balance control tasks including transfer, getting up and sitting on a chair, reach, turning and stepping.

5 years after surgery

Time and distance of COP displacement were found to be higher in the study group. From the research group performed the task slower and demonstrated greater COP displacement. Also distance in the frontal plane on B100 board was significantly worse in the THR group. There was significant difference in TUG, 3 m, FRT and CST between groups. Both tests assessing gait in patients after total hip replacement showed that they completed the task slower than members of the control group. Completing the TUG test by an individual from the study group took on average 1.64 s longer than in the control group, whereas the walking time over the distance of 3 m was 0.55 s longer. In the FRT trial the reach distance of THR patients were on average 3.9 cm shorter than of the control group. Furthermore, considerable differences were observed in the CST, where members of the control group did more repetitions than subjects in the study groups. It was found that there are not statistically significant

differences in the results of the BBS test between the study and the control group. Step Test results of individuals with prosthetic implants differed significantly from results in the control group. The differences were present when comparing to the control group (average 16.3) both the operated limb (mean 13.2; p < 0.001) and the limb without a prosthetic implant (mean 13.5; p < 0.002) in both cases people with total hip replacement conducted fewer repetitions.

Warenczack et al. 2019

THR GROUP: 30 patients (F 25, M 5; mean age 69.4 y)

CONTROL GROUP: 30 participants (F 25, M 5; mean age 68.8 y)

THR with anterolateral approach

A balance platform and a one-leg standing test (OLS) were used to assess static balance. The postural balance tests were performed on the Metitur Good Balance platform.

Static balance tests on the balance platform were conducted in several positions with different foot placement: normal standing, eyes open (NS EO) and eyes closed. The subjects were asked to maintain a motionless upright position with both arms along their sides and eyes looking at a target in front of them (barefoot). In the normal standing (NS) position the feet were placed precisely 20 cm apart. The duration of the tests with EO and EC was 30 s each. During the TP test (asymmetric position of feet) one foot was placed directly ahead of the other. We performed TP tests with the left foot in front (TLF) and with the right foot in front (TRF) separately. In the THR group, the placement of the operated limb in the front stance was called the TOF test, while the placement of the other limb in the front stance was called the TNF test. Time of test: 10 s. In 2TP the left or right foot was alternately placed in front of the other, but the feet were placed on both sides of a line that divided the platform into two parts (the line was tangent to the medial edge of the feet). Similarly, to the tandem test, the patients were examined with the operated (2TOF) and non-operated limb (2TNF) in the front. The length of the exercise was 20 s. When testing the leg standing position on the balance platform, the patients were asked raise one foot to the mid-calf level of the supporting leg but not touch the loaded limb. The test was stopped when the subject had to use the arms (touched the handrail) or used the raised foot (touched the floor). The procedure was usually stopped after two failed attempts or fear of falling and results were not recorded. Patients were examined when standing on the operated (1O) or non-operated limb (1 N) and the control group on the left (1 L) and right (1R) limb. Time of test: 5 s. During the one-leg standing test (OLS) the time of maintaining this position by the patients was measured. The placement of the limbs was the same as in the balance platform test. The subjects performed three attempts on each lower limb. The test ended when the subject used the raised foot (touched the floor) or moved the supporting leg on the ground or a significant loss of balance was observed or a maximum of 60 s elapsed. The patients performed the tests both on

the operated (OLS-O) and non-operated (OLS-N) limb and the control group on the left (OLS-L) and right (OLS-R) limb.

At the beginning of the rehabilitation process.

Significant imbalance in the sagittal plane during normal standing EO and EC positions were found in the THR group. No significant differences in the measured parameters were found during tests in tandem, the second form of tandem and one-leg standing positions in the groups. The mean time of standing on the operated limb in the THR group during the OLS test was significantly shorter than that in the control group.