Balance Cadera

VOL. 87-B, No. 10, OCTOBER 2005 1337

Improvements in balance after total hip replacement

M. Majewski, H. A. Bischoff-Ferrari, C. Grüneberg, W. Dick, J. H. J. Allum

From the University Hospital of Basel, Basel, Switzerland

�

M. Majewski, MD, Orthopaedic SurgeonDepartment of OrthopaedicsKantonsspital, CH-4410 Liestal, Switzerland.

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J. H. J. Allum, DSc, ProfessorDepartment of Otorhinolaryngology

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W. Dick, MD, Professor and Orthopaedic SurgeonDepartment of OrthopaedicsUniversity Hospital Basel, CH-4031 Basel, Switzerland.

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C. Grüneberg, PhD, Research LeaderEuropa Fachhlochschule FreseniusUniversity of Applied Sciences, Fachbereich Gesundheit Limburger Stra

σσ

e 2, 65510 Idstein, Germany.

�

H. A. Bischoff-Ferrari, MD, MPH, Assistant ProfessorDepartment of Rheumatology and Institute of Physical Medicine and RehabilitationUniversity Hospital of Zurich, CH-8091 Zurich, Switzerland.

Correspondence should be sent to Professor J. H. J. Allum; e-mail: [email protected]

©2005 British Editorial Society of Bone andJoint Surgerydoi:10.1302/0301-620X.87B10. 16605 $2.00

J Bone Joint Surg [Br]

2005;87-B:1337-43.

Received 8 April 2005; Accepted 4 May 2005

We have investigated whether control of balance is improved during stance and gait and sit-

to-stand tasks after unilateral total hip replacement undertaken for osteoarthritis of the hip.

We examined 25 patients with a mean age of 67 years (

SD

6.2) before and at four and 12

months after surgery and compared the findings with those of 50 healthy age-matched

control subjects. For all tasks, balance was quantified using angular measurements of

movement of the trunk.

Before surgery, control of balance during gait and sit-to-stand tasks was abnormal in

patients with severe osteoarthritis of the hip, while balance during stance was similar to

that of the healthy control group. After total hip replacement, there was a progressive

improvement at four and 12 months for most gait and sit-to-stand tasks and in the time

needed to complete them. By 12 months, the values approached those of the control group.

However, trunk pitch (forwards-backwards) and roll (side-to-side) velocities were less

stable (greater than the control) when walking over barriers as was roll for the sit-to-stand

task, indicative of a residual deficit of balance.

Our data suggest that patients with symptomatic osteoarthritis of the hip have marked

deficits of balance in gait tasks, which may explain the increased risk of falling which has

been reported in some epidemiological studies. However, total hip replacement may help

these patients to regain almost normal control of balance for some gait tasks, as we found

in this study. Despite the improvement in most components of balance, however, the deficit

in the control of trunk velocity during gait suggests that a cautious follow-up is required

after total hip replacement regarding the risk of a fall, especially in the elderly.

Most patients report considerable relief frompain and improved function after total hipreplacement (THR)

1-5

although the degree towhich the procedure influences post-operativebalance has not been previously studied.

Problems with balance and gait can occur inpatients with severe osteoarthritis (OA) of thehip because of damage to proprioceptors, andthey are further damaged as a result of capsu-lar excision during THR. In addition, weak-ness of the abductors, leg-length inequality, ashortened lever arm, a restricted range ofmovement, and altered weight-bearing mayimpair balance.

6,7

The functional outcome after THR may be

assessed by measuring the time needed to com-plete specific gait and balance tasks.

8-12

An alter-native, albeit more time-consuming method, isto measure angular movements of the bodywith a movement analysis system.

13,14

A sim-pler method, however, is to measure balance astrunk pitch (forwards-backwards) and roll(side-to-side) angles in addition to velocity dur-

ing stance, gait and sit-to-stand tasks. This lastmethod is the one which we used.

15,16

Our aim was to evaluate whether balanceperformance improved after THR for OA and,if so, whether it could return to normal.

Patients and Methods

Twenty-five consecutive patients (11 womenand 14 men) with a mean age of 67 years (

SD

6.2) were examined prospectively. The maincriterion for inclusion in the study was severe,concentric, unilateral OA of the hip (12 right,13 left) and typical symptoms of degenerativejoint disease. In all patients, the radiologicaldegeneration was grade 4, according to Kellgrenand Lawrence.

17

Patients were tested on threeoccasions: pre-operatively, when their symp-toms were most severe; and four months andone year after surgery. An adapted Harris hipscore was used for pre- and post-operative clin-ical and radiological comparisons.

18

Patients with bilateral OA of the hip wereexcluded, as were those with OA of the knee,

1338 M. MAJEWSKI, H. A. BISCHOFF-FERRARI, C. GRÜNEBERG, W. DICK, J. H. J. ALLUM

THE JOURNAL OF BONE AND JOINT SURGERY

ankle or foot. No patient had undergone any surgery on theipsilateral leg before this study, nor had any suffered fromother health problems which could have affected gait andbalance, such as spinal stenosis. All patients received thesame type of THR, a Morscher press-fit acetabular compo-nent (Zimmer, Winterthur, Switzerland) and a cementedMS-30 femoral component (Zimmer) inserted through atransgluteal approach with the patient in the supine posi-tion. All operations were performed either by or under thesupervision of an experienced surgeon (WD) with regionalanaesthesia being used in most cases. After surgery allpatients were mobilised fully weight-bearing with crutcheson the first post-operative day. They could sit on a hip chair,but were not allowed to cross their legs for six weeks.

A control group comprised 50 normal, healthy subjects,who were age- and gender-matched to each of the patientsfrom a database of normal individuals.

19

They had no com-plaints of vertigo or other problems affecting gait and bal-ance. The subjects in both the study and control groupsgave their written informed consent to participate in theinvestigation, which had received approval from the ethicalreview board of the hospital.

Balance assessment device.

Control of balance, in the formof trunk pitch (forwards-backwards) and roll (side-to-side)movements, was measured during the stance and gait tasksby the two angular velocity sensors (fibreoptic gyroscopes)of the SwayStar balance system (Balance InternationalInnovations GmbH, Iseltwald, Switzerland), which wasattached by a belt to the patient so that the sensors were at

the L2/3 level (Fig. 1). The sensors were connected by a ten-metre cable to a computer which sampled the angularvelocity signals every 100 ms and numerically integratedthe signals to yield angular displacement. The specifiedmaximum baseline drift of the sensors was 36˚/hr or0.01˚/s and the noise about this drift was 0.6˚/hr. Since themaximum task duration was 20 s, the maximum cumula-tive measurement error was 0.2˚.

Stance and gait tasks.

Patients were asked to perform aprotocol of five standard tasks derived from earlier publica-tions.

10,12

They consisted of one sit-to-stand, two gait andtwo stance tasks.

For the sit-to-stand task, we performed the first half ofthe timed get-up-and-go test.

20,21

For this, the patient sat ona height-adjusted stool with their knees flexed to 90˚. Oncommand they stood up, without placing their hands ontheir knees in order to lever themselves forwards and theythen walked a distance of three metres.

For the first gait task, the patients walked over a series offour low barriers, each 24 cm high and one metre apart. Forthe second, they walked up a set of stairs comprising twoupward and two downward steps each 23 cm high, withouthandrails.

For the first stance task, the patients stood on both legson a normal surface with their eyes open. For the second,they stood on both legs on a foam support surface withtheir eyes closed. The foam surface was 10 cm thick, 44 cmwide, 204 cm long and had a density of 25 kg/m

2

. For thestance tasks the patients stood without shoes for a maxi-

Fig. 1

Photograph showing the SwayStar balance system for measuring trunkpitch (forwards-backwards) and roll (side-to-side) angular movementsduring the stance and gait tasks. The belt was placed around the patientso that the sensors were positioned at level of L2/L3.

Pitch

Roll

Pitch

Roll

Pitch

Roll

40

0-10

An

gle

(˚)

40

0-10

An

gle

(˚)

40

0-10

An

gle

(˚)

0 1 2 3 4 5 6 7

Time (s)

0 1 2 3 4 5

Time (s)

0 1 2 3 4

Time (s)

a

b

c

Fig. 2

Traces showing the improved ability of a typical patient with a THR to risefrom a stool and walk three metres. Measurements were made during thisget-up-and-go task a) before, and b) at four and c) at 12 months after sur-gery. Forward pitch and rightward roll are represented by an upwarddeflection of the traces. They indicate a significant reduction in the timeneeded to complete the task, as well as a greater degree of trunk flexion.

IMPROVEMENTS IN BALANCE AFTER TOTAL HIP REPLACEMENT 1339

VOL. 87-B, No. 10, OCTOBER 2005

mum of 20 s, if possible. Two physiotherapists stoodbeside the patient throughout the tests in order to preventa fall.

The duration of the test was the time to completion of thetask or the time taken until a fall would have occurred butfor the action of the physiotherapist. The task protocol wasrepeated three times for each patient. The first occasion wasbetween two and five days before surgery. The second wasperformed four months later (mean 119 days,

SD

9.2) andthe third was at follow-up at 12 months (mean 391 days,

SD

8.6). Validation of these tasks had already been per-formed.

15

Analysis of data.

The method of data analysis has beendescribed previously.

15,16,19

From each recording the maxi-mum peak-to-peak excursions of pitch and roll angle andvelocity were calculated to yield five variables, with dura-tion, to quantify each task.

Before the statistical analysis, the peak-to-peak measure-ments were log transformed to change their distributionfrom Poisson-like to Gaussian.

19

A Kolmogorov-Smirnovtest was used to check this. A repeated measures analysis ofvariance was used to determine the effect of post-operativetime on the measurement variables. Individual variableswith a significant time effect were investigated using Bon-ferroni tests, with significance set at p

≤

0.05, in order todetermine if their mean values measured pre-operatively

and at four and 12 months, were different. In addition, themean values for these time periods were also comparedwith those of the control group.

Results

Get-up-and-go task.

The initial phase of the get-up-and-gotask is characterised by a rapid forward flexion of the trunkwhich provides the momentum to stand and to start walk-ing. Clearly, the inability to pitch the trunk forwards rap-idly enough, as may occur with severe OA of the hip,compromises the ability to complete this task (Fig. 2).

In the patients, pitch velocity increased after surgery atfour (p = 0.049) and at 12 months (p = 0.001), approachingthe value of the normal control group by 12 months. Thedifference between the patients and the control group wassignificantly different pre-operatively (p = 0.001) and atfour months (p = 0.011), but not at 12 months. Coinciden-tal with this increase in pitch velocity, the significant reduc-tion in the amplitude of the pitch angle before surgery(p = 0.001) had also improved at four (p = 0.003) and 12months (p = 0.011) post-operatively. However, forwardtrunk flexion remained reduced after THR (p = 0.01, com-pared with controls) although pitch velocity had increased.

The roll velocity, which was not significantly abnormalbefore surgery (p > 0.05), increased slightly at four months(p = 0.05), and more so at 12 months (p = 0.012). This sug-

Table I.

Statistical differences (p values) for the 25 patient with a THR at the three time intervals and between the patients and the 50 normal subjects

Variable (peak-to-peak amplitude)

Duration Pitch angle (˚) Pitch velocity

†

Roll angle

‡

(˚) Roll velocity(s)

Get-up-and-go task4 months compared with pre-operatively 0.001 (shorter)

*

0.049 (faster)1 year compared with pre-operatively 0.026 (shorter) 0.001 (faster) 0.013 (larger)Pre-operative compared with normal 0.001 (smaller)

‡

0.001 (slower)4 months compared with normal 0.003 (smaller) 0.011 (slower)1 year compared with normal 0.011 (smaller) 0.012 (larger)

Barriers task4 months compared with pre-operatively1 year compared with pre-operatively 0.002 (shorter) 0.003 (larger)Pre-operative compared with normal 0.001 (longer) 0.004 (larger) 0.001 (larger)4 months compared with normal 0.004 (larger) 0.004 (larger) 0.023 (larger)1 year compared with normal 0.002 (larger) 0.033 (larger) 0.011 (larger) 0.006 (larger)

Stairs task4 months compared with pre-operativelyPre-operative compared with 1 year 0.001 (shorter)Pre-operative compared with normal 0.029 (longer) 0.042 (smaller)4 months compared with normal 0.045 (smaller)1 year compared with normal 0.025 (shorter) 0.022 (smaller)

Standing (eyes open) taskPre-operative compared with normal 0.005 (smaller) 0.009 (smaller)4 months compared with normal 0.006 (smaller) 0.001 (smaller)1 year compared with normal 0.001 (smaller) 0.001 (smaller) 0.001 (smaller) 0.001 (smaller)

Standing (eyes closed) taskPre-operative compared with normal 0.026 (smaller)4 months compared with normal 0.023 (smaller) 0.034 (smaller)1 year compared with normal 0.041 (smaller) 0.009 (smaller)

* duration (shorter) implies, for example, if the four-month is compared with the pre-operative result, that the time to complete the task was shorter.Duration (longer) implies the converse.† velocity (faster) implies, for the get-up-and-go task that trunk pitch velocity was faster at four months compared with pre-operatively. Velocity(faster) implies the converse. For other tasks, the term larger (or smaller) velocity is used.‡ angle (smaller) implies, for example, that the amount of trunk movement was less than normal. Angle (larger) implies the converse.



gested a higher, possibly unstable roll velocity at 12 months(p = 0.013) compared with the situation before operation.

The time needed to complete the get-up-and-go-taskimproved significantly after surgery. This was already obvi-ous by four months (p = 0.001) and was maintained at 12months (p = 0.026; Table I).

Barriers task.

The mean values for all the patients showed aprogressive decrease in pitch and roll angles and a progres-sive increase in pitch and roll velocity at four and 12months post-operatively for the barriers task (Fig. 3). Theseangles approached the values of the normal control group(Fig. 4).

Pitch velocity increased significantly at 12 months com-pared with pre-operatively (p = 0.003) reaching valuesexceeding the normal (p = 0.033). Similarly, roll velocity inthe patients increased to a value beyond the normal atfour months (p = 0.023) and remained so at 12 months(p = 0.006). Compared with the control group, measure-ments of the amplitude of the pitch and roll angle showedsignificantly higher values before surgery and after four and12 months (Table I).

The time needed to complete the barriers task was signif-icantly increased before surgery in the patients when com-pared with the control group (p = 0.001), but by the 12-month follow-up was closer to that of the control group(p = 0.002). Thus, by 12 months the patients could com-plete the task as quickly as the normal group but their trunk

Trunk velocity (˚/s)

Trunk angle (˚)

Roll -16 -8 0 8 16

-12 -8 -4 0 4 8 12

80

40

0

-40

-80

12

8

4

0

-4

Pit

chP

itch

Fig. 3a

Illustration of trunk pitch and roll velocity angle and for a typical patient a) before and b) at four and c) 12 months after THR while performingthe barriers task, and d) for the normal control group. Each recording is shown as an x-y plot of either pitch versus roll angle (upper row) orpitch versus roll velocity (lower row). An envelope has been drawn around the excursions. The maximum peak-to-peak excursions in each direc-tion were analysed. There is a reduction of pitch and roll angle and an increase in pitch and roll velocity with time.

Fig. 3b Fig. 3c Fig. 3d

180

160

140

120

100

80

60

40

20

0

30

25

20

15

10

5

0

Velo

city

(˚/s

)A

ng

le (

˚)

Pre-operative 4 mths 12 mths Normal control group

Roll Pitch

Roll Pitch

a

b

Fig. 4

Bar charts showing the mean, and SEM values for a) the roll and pitchvelocity and b) the roll and pitch angle for the barriers task. The arrowindicates significant (p < 0.05) changes in the mean with time. The meanvalue approaches the normal mean value, with velocities becominggreater than normal. The mean values are greater than median valuesbecause the measurements have an asymmetrical distribution across thesample populations1 (* statistically significant p < 0.05).



movements were larger and faster, indicative of residualinstability (Table I).

Stairs task.

Walking up and down stairs involves clearingthe foot over the height of the step, but also requires load-bearing capabilities to pull the body either up to the nextstep or to stabilise it when stepping down.

The mean duration of all participants for this task isillustrated in Figure 5. The duration reduced significantlyafter one year compared with the normal control group(p = 0.025) and showed a significant reduction in the timeneeded to complete the task compared with pre-operatively(p = 0.001).

We also observed small reductions in the pitch angle ofthe trunk after four (p = 0.045) and 12 months (p = 0.022),possibly caused by the effects of improved movements ofthe hip on movements of the trunk, although these changeswere not as significant as those for the get-up-and-go tasks(Table I).

Stance on two legs with the eyes open or closed.

At all timepoints there was no deficit of balance during the stancetasks. The pitch and roll angle and the pitch and roll velo-city for normal standing with the eyes open were signifi-cantly less than those of the control group at all time points.Less roll sway was seen when standing with eyes closed ona foam support surface (Fig. 6). Thus, roll angle and rollvelocity appeared to be lower in the patients than in thecontrol group under both stance conditions, suggestingthat the patients stood more stiffly than the control group(Table I).

Pre-operative

4 mths

12 mths

Normal control group

8

7

6

5

4

3

2

1

0

Du

rati

on

(s)

Fig. 5

Bar charts showing the mean duration, and SEM values for the task ofwalking up and down stairs. The time needed to complete the task wasconsiderably shorter at 12 months (arrow), when the patients were fasterthan the normal (*statistically significant p < 0.05).

Pre-operative

4 mths

12 mths

Normal control group

12

10

8

6

4

2

0

4

3

2

1

0

Velo

city

(˚/s

)A

ng

le (

˚)

Roll Pitch

Roll Pitch

a

b

Fig. 6

Bar charts showing the mean values for trunk sway a) velocity and b) angle measurements and SEM values forthe stance task when standing on a foam support surface with the eyes closed (*statistically significantp < 0.05).



Clinical and radiological findings.

Pre-operatively, all patientshad concentric arthritis of the hip with greatly reduced jointspace and sclerosis of subchondral bone. The mean Harriship score was 42 (23 to 52). At follow-up at one year thishad risen to 95 (71 to 100). There were no local or systemiccomplications and no evidence of loosening of the compo-nents. Comparison of the pre- and post-operative radio-graphs showed no major differences in parameters such asthe position of the centre of the hip or the abductormoment. Pre-operatively, most patients had a slight limb-length discrepancy, with a mean of 0.5 cm (0 to 1) and allcomplained of pain during daily living. Post-operativelytwo patients had a limb-length discrepancy of 0.5 cm andtwo of 1 cm. Six complained of slight, occasional painwhich did not compromise daily living.

Discussion

Our study has shown that balance during everyday gait andsit-to-stand tasks is significantly altered by severe OA of thehip. Patients undergoing THR were assessed before surgery,and at four and 12 months, in order to track improvementsin the control of balance after surgery. Their performancewas also compared at each time point with that of the age-matched healthy control group by using measurements oftrunk angular movement.

In individuals undergoing THR, balance while walkingover low barriers and while getting up from a stoolimproved significantly after surgery and approached thevalues of the age-matched control group at four and 12months. For these tasks abduction, flexion of the hip andstrength are critical. Almost normal functional perfor-mance at 12 months suggested that surgery successfullyrestored joint mobility and control in these patients.

However, despite the improvement in most balance mea-surements for gait and sit-to-stand tasks, roll velocitiesexceeded values of the normal control group at follow-upat 12 months. Similarly, the roll angular amplitudesremained larger than those of the control group for the bar-riers task. This suggests that balance for these tasks mayeither need more time to recover or that there may be someimpairment which cannot be restored after THR. In ourearlier studies on other groups, abnormal roll during gaittasks correlated with the incidence of falls.

15,22

Initially, balance while standing appeared not to be com-promised in patients with severe OA of the hip. Roll duringboth stance tasks was less than for the control group anddid not change after surgery. In both stance tasks, rollangles and roll velocities when standing were lower thanthose in the control group suggesting that movements of thetrunk and pelvis were restricted, possibly by general stiff-ness. One interpretation of these results is that it is prefera-ble to assess balance by means of gait rather than bystanding tasks in the follow-up of patients after THR, sincethe gait tasks were the most responsive to THR.

In contrast to the remaining deficits of balance in thepatients, the time needed to perform different tasks gener-

ally improved towards that of the healthy control group bythe follow-up at 12 months. Therefore, timing assessmentsduring functional tasks may be of limited value if otheraspects of the control of the balance are missed. This maybe especially important since a large number of the patientsundergoing THR are over the age of 65 years, an age whenfalls begin to occur frequently.

7

It is currently unknown ifthe risk of falling in individuals with OA of the hip isreduced after THR.

Balance has not been previously tested during functionaltasks of the lower limbs in patients undergoing THR. Ourfindings of improved function are supported, however, byseveral studies which addressed alterations in the elec-tromyographic (EMG) patterns and changes in musclestrength in the leg muscles in patients with THR. Long etal,

23

for example, examined such patients before and afteroperation by both EMG and gait analysis. Pre-operatively,they found that the EMG patterns during gait were abnor-mal, caused by an absence of activity in gluteus medius, ten-sor fascia lata and rectus femoris during walking. Twoyears after operation these abnormal patterns had disap-peared. Murray et al

24

also found that there was a signifi-cant improvement in almost all aspects of functional gaitperformance two years after surgery. Similarly, Shih et al

25

showed improved muscle strength in patients undergoingTHR at six months and at one year after operation. Thesefindings support our assumption that post-operativeincreases in muscle strength may well underlie the func-tional improvements in task performance which we saw inthe patients with THR.

The improvements in balance which we observed could,however, be the result of increased strength and/or jointflexibility. The increased speed with which patients wereable to perform gait and sit-to-stand tasks at four and 12months after surgery was probably because of greatermuscle strength.

26

Increased joint stiffness is a commonclinical sign in patients with OA of the hip and is related tobalance.

7,13,24

Our analysis showed that patients with severe OA of thehip have less roll than normal subjects during stance. Thiswas unaltered after THR and suggested that these patientswere standing more stiffly than the control group even aftersurgery. We have previously addressed the question of stiff-ness of the hip in an experiment in young normal subjectswho wore a cast to give artificial stiffness at the hip and pel-vis.

27

We found the young subjects had faster roll velocities,but unchanged trunk pitch and roll angles, when correctingdisturbances in stance. These findings were similar to thebalance deficit of our patients when performing the barriersand get-up-and-go tasks. Consequently, our results in theartificially-stiffened young subjects may explain some ofthe inability of patients with a THR to control their move-ments adequately because of a generally increased stiffnessat the hip and pelvis.

27,28

We, therefore, suggest that increased stiffness in patientswith severe OA of the hip may lead to better control of bal-



ance in the form of less pitch and roll, while standing ontwo legs. By contrast, a deficit of balance occurs if the trunkcannot hinge into an upright position with respect to thepelvis and legs while walking. The trunk cannot counter-rotate as much because of the underlying stiffness, andmust sway more to follow the course of leg abduction. Insummary, the larger roll velocities seen during gait taskssuggest that overall stiffness is only partly reduced after sur-gery, while increased strength, reduced pain and greaterflexibility of the hip after THR lead to improved control ofthe trunk and balance. Future studies need to address howthe larger roll velocities relate to both the risk of a fall andlong-term function in patients undergoing THR.

A patient’s ability to balance is related to his or her joint-position sense, derived primarily from receptors within mus-cle-tendon units and the joint capsule receptors. It is possi-ble that this sense is compromised in patients with artificialjoints.

29

Indeed, our findings suggest that patients undergo-ing THR approach the levels of the control group after sur-gery in most tasks except for their control of trunk roll.

It is unlikely that the improvements which we noted infunctional performance were simply because of a learningeffect. The periods of four and 12 months as inter-test inter-vals tend to preclude such an effect. Normal subjects, whenretested within a shorter interval of three weeks, show nosignificant learning effect.

16

Our study acts as a basis for future investigations into thebenefits of different surgical techniques and implants but,more importantly, for the ongoing assessment of functionalimprovement after THR and any potential risk of a fall.The use of simple body-worn angular velocity transducersto quantify control of the trunk, and thereby performanceof gait and balance, has proved to be very useful for thispurpose.

This work was supported by grants from the Swiss National Science Founda-tion (31-59319.99) and the Free Academic Society of Basel to Professor J. H. J.Allum. We would like to thank H. U. Schläpfer, R. Akos and the team of physio-therapists at the Felix Platter Hospital in Basel for their co-operation in carryingout the protocols for this study.

No benefits in any form have been received or will be received from a com-mercial party related directly or indirectly to the subject of this article.

References

1. Felson DT, Zhang Y.

An update on the epidemiology of knee and hip osteoarthritiswith a view to prevention.

Arthritis Rheum

1998;41:1343-55.

2. Guccione AA, Felson DT, Anderson JJ, et al.

The effects of specific medical con-ditions on functional limitations of elders in the Framingham study.

Am J PublicHealth

1994;84:351-8.

3. Liang MH, Bischoff HA, Roos EM.

Outcome assessment in osteoarthritis: a guidefor research and clinical practice. In: Brandt KD, Doherty M, Lohmander LS, eds.

Osteoarthritis

. Second ed. New York: Oxford University Press, 2003:381-90.

4. Harris WH, Sledge CB.

Total hip and total knee replacement (2).

N Engl J Med

1990;323:801-7.

5. Mahomed NN, Barrett JA, Katz JN, et al.

Rates and outcomes of primary and revi-sion total hip replacement in the United States medicare population.

J Bone JointSurg [Am]

2003;85-A:27-32.

6. Nallegowda M, Singh U, Bhan S, et al.

Balance and gait in total hip replacement:a pilot study.

Am J Phys Med Rehabil

2003;82:669-77.

7. Skinner HB.

Pathokinesiology and total joint arthroplasty.

Clin Orthop

1993;288:78-86.

8. El-Kashlan HK, Shepard NT, Asher AM, Smith-Wheelock M, Telian SA.

Eval-uation of clinical measures of equilibrium.

Laryngoscope

1998;108:311-19.

9. Gill-Body KM, Krebs DE, Parker SW, Riley PO.

Physical therapy management ofperipheral vestibular function: two clinical case reports.

Phys Ther

1994;72:129-42.

10. Shumway-Cook A, Horak FB.

Assessing the influence of sensory interaction onbalance: suggestion from the field.

Phys Ther

1986;66:1548-50.

11. Soderman P, Malchau H.

Is the Harris hip score system useful to study the outcomeof total hip replacement?

Clin Orthop

2001;384:189-97.

12. Tinetti ME.

Performance-orientated assessment of mobility problems in elderlypatients.

J Am Geriatr Soc

1986;34:119-26.

13. Arnold W, Schliebe G.

Gait analysis in patients with total hip endoprosthesis: partII: pre- and postoperative gait analysis.

Z Gesamte Inn Med

1992;47:15-20 (in Ger-man).

14. Ferrigno G, Pedotti A.

Elite: a digital dedicated hardware system for movementanalysis via real-time TV signal processing.

IEEE Trans Biomed Eng

1985;32:943-50.

15. Adkin AL, Allum JHJ, Bloem BR.

Trunk sway measurements during stance andgait tasks in Parkinson’s disease.

Gait and Posture

2005: in press.

16. Allum JH, Adkin AL.

Improvements in trunk sway observed for stance and gait tasksduring recovery from an acute unilateral peripheral vestibular deficit.

Audiol Neuroo-tol

2003;8:286-302.

17. Kellgren JH, Lawrence JS.

Radiological assessment of osteo-arthrosis.

AnnRheum Dis

1957;16:494-502.

18. Harris WH.

Traumatic arthritis of the hip after dislocation and acetabular fracture:treatment by mold arthroplasty: an end-result study using a new method of resultevaluation.

J Bone Joint Surg [Am]

1969;51-A:737-55.

19. Gill J, Allum JH, Carpenter MG, et al.

Trunk sway measures of postural stabilityduring clinical balance tests: effects of age.

J Gerontol A Biol Sci Med Sci

2001;56:438-47.

20. Bischoff HA, Stahelin HB, Monsch AU, et al.

Identifying a cut-off point for normalmobility: a comparison of the timed ‘up and go’ test in community-dwelling and insti-tutionalised elderly women.

Age Ageing

2003;32:315-20.

21. Podsiadlo D, Richardson S.

The timed “up & go”: a test of basic functional mobilityfor frail elderly persons.

J Am Geriatr Soc

1991;39:142-8.

22. De Hoon EWJ, Carpenter MG, Salis C, et al.

Quantitative assessment of the‘stops walking while talking test’ in the elderly.

Arch Phys Med Rehab

2003;89:838-42.

23. Long WT, Dorr LD, Healy B, Perry J.

Functional recovery of noncemented total hiparthroplasty.

Clin Orthop

1993;288:73-7.

24. Murray MP, Gore DR, Brewer BJ, Mollinger LA, Sepic SB.

Joint function afterhip arthroplasty: a four-year follow-up of 72 cases with Charnley and Muller replace-ments.

Clin Orthop

1981;157:119-24.

25. Shih CH, Du YK, Lin YH, Wu CC.

Muscular recovery around the hip joint after totalhip arthroplasty.

Clin Orthop

1994;302:115-20.

26. Luepongsak N, Amin S, Krebs DE, McGibbon CA, Felson D.

The contribution oftype of daily activity to loading across the hip and knee joints in the elderly.

Osteo-arthritis Cartilage

2002;10:353-9.

27. Grüneberg C, Bloem BR, Honegger F, Allum JHJ.

The influence of artificiallyincreased hip and trunk stiffness on balance control in the pitch and roll planes.

ExpBrain Res

2004;157:472-85.

28. Tinetti ME, Speechley M, Ginter SF.

Risk factors for falls among elderly personsliving in the community.

N Engl J Med

1988;319:1701-7.

29. Skinner HB, Barrack RL, Cook SD, Haddad RJ Jr.

Joint position sense in totalknee arthroplasty.

J Orthop Res

1984;1:276-83.

Balance Cadera

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