ORIGINAL ARTICLE

Arthroscopic synovectomy in the treatment of functional ankleinstability: outcomes and gait analysis

Egemen Altan • Mehmet Ugur Ozbaydar •

Murat Tonbul • Hakan Senaran • Yener Temelli •

Ekin Akalan

Received: 18 February 2014 / Accepted: 16 March 2014

� Springer-Verlag France 2014

Abstract

Background Natural consequence of repetitive ankle

sprains is the chronic ankle instability. Objective of this

study was to clarify the gait patterns of functional ankle

instability (FAI) patients after arthroscopic synovectomy,

but also assessment of postoperative recovery.

Patients and methods Arthroscopic synovectomy was

performed to 14 FAI patients with history of unilateral

repetitive ankle sprains, pain, and subjective sensation of

instability. At a mean 54 months of follow-up (27–84),

clinical assessment was conducted with respect to pain,

number of ankle sprains, and American Orthopaedics Foot

and Ankle Society (AOFAS) scores. Gait analysis was

conducted to determine the temporospatial, kinetic and

kinematic parameters at the last follow-up.

Results Mean AOFAS scores increased from 68 (range

55–75) to 89 (range 77–100) points (P \ 0.01). Mean

ankle sprains was 13 in a period of 23 (range 14–48)

months (0.58 per month) and decreased to three sprains in a

mean time period of 54 months (0.053 per month)

(P \ 0.01). Mean preoperative and postoperative VAS

scores were 8.0 and 2.9, respectively (P \ 0.01). During

gait analysis, no significant differences were found in ankle

joint, including foot progression angles, ankle dorsi-plantar

flexion degrees and ground reaction forces (P [ 0.01).

Among temporospatial parameters, only double support

time showed a significant difference (P \ 0.01). All

patients were satisfied from the procedure and returned to

their previous activity level.

Conclusion Improved long-term clinical results and

scores were obtained in our patient group when compared

with the preoperative scores. Also, three-dimensional gait

analysis showed that the involved ankles demonstrate

similar gait patterns to the uninvolved ankles in patients

with FAI.

Keywords Arthroscopy � Synovectomy � Ankle �Gait analysis � Instability

Introduction

Ankle sprains are the most common type of ankle injury

[1]. The development of repetitive ankle sprains and per-

sistent symptoms after injury has been termed ‘‘chronic

ankle instability’’ (CAI) [2]. Within 3 years of their first

ankle-sprain incident, 34 % of those injured incur a

residual problem [3]. Freeman first described ‘‘functional

instability’’ (FI) and introduced his articular deafferenta-

tion theory in which FI is attributable to proprioceptive

deficits [4]. A more recent definition of FI is ‘‘the occur-

rence of recurrent ankle instability and the sensation of

E. Altan (&) � H. Senaran

Orthopaedics and Traumatology Department, Medical Faculty,

Medical School of Selcuk University, Konya, Turkey

e-mail: egemenaltan@hotmail.com

M. U. Ozbaydar

Orthopaedics and Traumatology Department, Acibadem

University Hospital, Istanbul, Turkey

M. Tonbul

Orthopaedics and Traumatology Department, Namik Kemal

University Hospital, Tekirdag, Turkey

Y. Temelli

Orthopaedics and Traumatology Department, Istanbul Medical

Faculty of Istanbul University, Istanbul, Turkey

E. Akalan

Physiotherapy and Rehabilitation Division, Istanbul University,

Istanbul, Turkey

123

Eur J Orthop Surg Traumatol

DOI 10.1007/s00590-014-1444-x

joint instability due to the contributions of proprioceptive

and neuromuscular deficits’’ [5]. However, mechanical

instability (MI) can be defined with clinical findings such

as pathological laxity, impaired arthrokinematics, and a 5�difference in the talar test [2]. Functional instability, as

opposed to MI, describes the situation of subjective giving

way, pain, and instability without anatomic ligamentous

incompetence [4].

Anterolaterally localized hypertrophic synovitis was

demonstrated arthroscopically in patients suffering from

repetitive ankle sprains [6–11]. Also, good-to-excellent

results following arthroscopic synovectomy have been

demonstrated for the treatment of ankle instability and

related impingement syndromes [6, 7, 9–12]. Gait analysis

is an important tool in the objective assessment of patients

with ankle instability. No study to date has utilized gait

analysis for functional ankle instability (FAI) patients who

have undergone arthroscopic synovectomy. Another

residual problem is the fear of the ankle ‘‘giving way’’,

which continues to worsen over time for FAI patients.

Also, return to the patient’s previous activity level is clo-

sely correlated with increased proprioceptive capacity [13].

The purpose of this study was to evaluate and compare

the differences between the injured and uninjured limbs of

FAI patients after arthroscopic synovectomy by means of

gait analysis, and to assess the outcomes in terms of

postoperative recovery, such as the frequency of ankle

sprains and American Orthopaedics Foot and Ankle Soci-

ety (AOFAS) scores. We hypothesized that the gait

parameters of FAI patients who experienced improvements

after arthroscopic synovectomy in terms of subjective cri-

teria would not demonstrate any difference from the con-

tralateral uninvolved side during long-term follow-up.

Materials and methods

The project was approved by the local ethics committee,

and written consent was obtained prior to testing. The

criteria for inclusion in this study, which were stated as

CAI by Caufield et al., were the presence of unilateral,

repetitive ankle sprains, ongoing pain when bearing

weight, tenderness localized to the anterolateral aspect of

the ankle, recurrent swelling, a feeling of the ankle giving

way, and weakness [14]. All patients had failed to respond

to at least 6 months of conservative treatment prior to

surgery, which consisted of physical therapy, propriocep-

tive training, and bracing. The exclusion criteria were as

follows: follow-up time of less than 2 years; history of

fracture, or impairment affecting either lower extremities

or acute ankle sprain in the 3 months prior to participation

to the study; patients with MI; and vestibular or neuro-

logical disorders leading to balance problems.

In order to exclude MI, a clinical anterior drawer and/or

talar tilt tests were conducted in all patients [15]. In com-

bination with the stress fluoroscopy, where there was

markedly asymmetric anterior laxity of the talocrural joint

([5 mm), an open lateral stabilization procedure was per-

formed and excluded from the study. Furthermore, preop-

erative magnetic resonance imaging (MRI) scans were

reviewed for all patients in order to document the intact or

attenuated (four patients) anterior talofibular ligament

(ATFL) and hypertrophic synovitis. There was not an

obvious bony or soft tissue impingement in the images.

Mainly, we used these criteria in order to distinguish FI

patients from MI patients as MI was not the subject of this

study. Thus, the patient population of our study primarily

included patients who complained of recurrent instability

and giving-way symptoms with a structurally intact ATFL

as confirmed with the MRI.

Retrospectively, 16 out of 35 patients met the above

criteria for functional instability. These patients were

treated between May 2001 and July 2006; fourteen were

ready for final follow-up and agreed retrospectively to

participate in the study.

Arthroscopic synovectomy was performed on all

patients with standard portals by the same surgeon. Ante-

rolaterally localized hypertrophic synovitis and scar tissue

were observed and debrided in all patients. Normal, unin-

jured ankles from the same patients served as the control.

The patients’ AOFAS and VAS scores were compared with

their preoperative scores (Table 1). The number of ankle

sprains was assessed with respect to time periods, and

corrected values were set as per months, preoperatively and

postoperatively (Table 1). Double support time, average

stance-phase percentage, and maximal moment values of

both ankles are shown in Table 2. A standardized home-

exercise protocol was given to all patients to carry out for

3 months after surgery. No additional physical therapy was

required for patients.

Patients were analyzed at their last follow-up (mean

54 months) using a three-dimensional (3D) motion analysis

system consisting of six cameras shooting at 100 frames

per second (Elite system, BTS S.p.A., Milan, Italy). The

subjects were barefoot during testing. A total of 22 retro-

reflective markers were placed at anatomically significant

locations on the body. Markers were attached to seventh

cervical vertebrae, sacrum, and bilaterally to both acro-

mion, superior anterior iliac spine, trochanter major, mid-

lateral of the thigh, lateral aspect of the knee joint line,

head of fibula, midlateral of the shank, lateral malleolus,

the heel, and fifth metatarsophalangeal joint. The walking

pace chosen for this study represented the subjects’ most

comfortable and natural walking speed across a 15-m

walkway. Kinematic, kinetic, and temporospatial parame-

ters were obtained after computer-aided evaluation of the

Eur J Orthop Surg Traumatol

123

variables, such as tracking, elaboration, cycles determina-

tion, and interpolation. A force plate was used to measure

ground reaction force (GRF), and values for each task were

normalized to body weight. For familiarization purposes,

patients completed three practice trials to ensure that they

were striking the floor naturally, without targeting. The

results of the five valid trials in which the patient’s foot

landed fully on the force plate were considered for

analysis.

Due to the small number of participants, nonparametric

statistical methods were used. Because the sides that had

been operated upon are related to the uninjured sides, two

related samples were compared using a nonparametric

Wilcoxon statistical test. Significance level was set a

priori at P B 0.01. The data were analyzed using the

SPSS (Version 17.0, SPSS Inc., Chicago, IL, USA) soft-

ware. Statistical comparisons of the gait parameters were

affected by priori power in some cases. Power calcula-

tions depended on the sample size (n = 14), the standard

deviation of non-operated measurements, and the signifi-

cant difference (10 %) of non-operated measurements

(Table 4).

Results

Eight patients had sustained an injury while walking, while

the remaining six patients had sustained an injury at the

gym. All injuries occured as the result of inversion, and the

mean time of injury to time of surgery was 12 months

(range 8–16) for the patients. Other probable causes of

chronic ankle pain, such as osteochondral lesions of the

talus, peroneal tendon pathologies, arthritis, medial liga-

ment injuries, and subtalar pathologies, were excluded

through MRI verification. Varying amounts of hypertro-

phic synovitis can be seen in all patients with MRI.

Demographic and anthropometrical characteristics of the

subjects are shown in Table 1.

Follow-up averaged 54 (range 27–84) months. Mean

AOFAS scores increased from 68 to 89 points (P \ 0.01).

All of the patients had a satisfactory outcome from the pro-

cedure and returned to their previous activity levels. There

were no complications in any of the patients. Although some

patients had recurrent sprains postoperatively, all of the

patients reported that they feel more secure when compared

with the preoperative conditions. The frequency of the each

patients’ ankle sprains decreased significantly, and the mean

number of ankle sprains was 13 over a mean period of

23 months (0.58 per month), and decreased to three sprains

over a mean period of 54 months (0.05 per month; P \ 0.01;

Table 1). The mean preoperative and postoperative VAS

scores were 8.0 and 2.9, respectively (P \ 0.01; Table 3).

Among temporospatial parameters, only double support time

showed a significant difference (P \ 0.01; Table 2).

In the ankle joint, peak dorsiflexion (P = 0.34), range of

motion of the stance phase (P = 0.08), and dorsiflexion

deficits (P = 0.17) during initial contact were evaluated,

and there was no significant difference between the

Table 1 Characteristics of the

individuals with functional

ankle instability

Gender Age Body mass

(kg)

BMI Side Height

(cm)

Duration of complaints

(months)

Sprains

(postoperative)

1 F 32 78 27 R 170 16 0

2 M 33 79 26 R 173 15 7

3 M 35 88 28 R 176 12 5

4 F 65 92 37 R 157 12 0

5 M 41 78 25 R 176 9 0

6 M 34 68 26 R 177 8 0

7 F 35 78 30 R 162 8 5

8 F 34 96 33 R 170 16 0

9 F 53 66 25 R 164 10 6

10 F 28 63 22 R 170 8 0

11 M 22 66 23 R 169 11 6

12 M 49 91 30 R 174 15 5

13 M 41 105 39 L 165 14 5

14 F 53 90 35 R 160 13 3

Table 2 Double support time, percentage of stance phase, and

maximal moment values of involved and uninvolved ankles

Involved

ankles

Uninvolved

ankles

Significancy

Double support time

(%stride)

9.6 7.9 P \ 0.01

Average stance phase

(%)

58.3

(56–61)

58.9 (57–62) P = 0.10

Maximal moment

(Nm/kg)

1.69 1.61 P = 0.069

Eur J Orthop Surg Traumatol

123

operated and uninjured sides (Fig. 1). The ankle dorsi-

plantar flexion moment was also assessed. Peak moment

values coincided in the same periods of the gait cycle

without any significance (P = 0.69; Fig. 2; Table 4).

Foot progression angles showed no significant differ-

ences between the operated and uninjured ankles during the

whole gait (P = 0.97) and particularly during the loading

phase (P = 0.86; Fig. 1).

Review of the GRF data in this analysis revealed

insignificant differences between groups. The mean GRFs

are shown in relation to the laboratory coordinate system

(Fig. 3). A vertical GRF equal to that of the uninjured

ankle was achieved by the operated ankle during the stance

phase of shock absorption (P = 0.75) and the formation of

impulse (P = 0.11). On the anterior–posterior trajectory,

the average GRF values were oriented more posteriorly

during the loading phase on the operated side, without any

significance (P = 0.11). In the medial–lateral plane, initial

contact (0–10 %) and loading phases (10–30 %) were

compared between the sides. In these phases, no

Fig. 1 Average values of foot progression (a) and ankle dorsi-plantar flexion (b) degrees of operated and uninvolved sides

Fig. 2 Ankle joint power (left side) (W/kg) and ankle moment (right side) (Nm/kg) of operated and uninvolved sides

Table 3 Comparison of

preoperative and postoperative

AOFAS, VAS, and the mean

number of ankle sprains

* Priori power of test is more

than 0.500

Parameters Preoperatively

(mean)

Postoperatively

(mean)

Priori power

analysis

Significancy

AOFAS score 68 89 1.000* P \ 0.01

VAS 8.0 2.9 0.906* P \ 0.01

Mean number of ankle sprains

(per month)

0.58 0.05 0.971* P \ 0.01

Eur J Orthop Surg Traumatol

123

differences were observed between the groups (P = 0.58,

P = 0.75; Table 4).

Discussion

Functional instability and MI are two possible causes of

CAI [2]. Although mechanical and functional instability

may occur in isolation, when combined they may con-

tribute to CAI [2]. MI is referred to as an increased flexi-

bility and joint laxity and is usually attributed to damage to

the ligaments of the ankle [2, 8]. After repetitive ankle

sprains, individuals may develop chronic instability dem-

onstrating laxity and MI. Some individuals with chronic

ankle instability may present proprioceptive deficit, mus-

cular weakness, impaired balance control, and increased

neuromuscular reaction time, leading to FI [5].

Our study population was composed of a homogeneous

group in means of FAI. The gait parameters of this isolated

group have rarely been reported upon in the literature. The

overall goal of this study was to present the gait patterns of

arthroscopically treated FAI patients and compare them

with the uninvolved sides of the same patients. In our

study, a three-dimensional gait analysis was used to eval-

uate the differences in gait cycles, and a subjective

assessment was conducted with clinical results and scoring

systems. We believe this to be the first study to evaluate

gait parameters in coordination with clinical outcomes after

arthroscopic synovectomy over a long-term follow-up.

Previous studies employing gait analysis have demon-

strated altered gait patterns and postural control deficits in

CAI patients, particularly for FAI [14, 16–21]. In our study,

however, no significant differences were found between the

operated and uninvolved sides. FAI patients experienced

fewer ankle sprains and demonstrated improved clinical

results after arthroscopic synovectomy and debridement. It

should be noted that the AOFAS score has not been vali-

dated as an outcome measure; however, it has been widely

used for assessment of CAI and is directly related with

Table 4 Group comparisons of ankle kinetic, kinematic and GRF

variables

Parameters Median Mean SD Priori

power

analysis

P value

Peak ankle power

(OS)

1.74 1.88 0.20 0.496a 0.69

Peak ankle power

(C)

2.03 2.08 0.25

Peak dorsiflexion

(OS)

12.12 13.38 0.98 0.930 0.34

Peak dorsiflexion

(C)

14.64 14.26 1.01

Heel strike plantar

flexion (OS)

-1.39 -1.25 1.17 0.054a 0.08

Heel strike plantar

flexion (C)

0.97 0.75 0.94

Foot progression

angle (OS)

-19.14 -16.25 1.60 0.610 0.97

Foot progression

angle (C)

-15.89 -15.58 1.70

Foot progression

angle during

stance (OS)

-18.89 -16.39 1.84 0.517 0.86

Foot progression

angle during

stance (C)

-17.65 -15.60 1.90

Fore-after GRF (OS) -0.08 -0.07 0.05 0.491a 0.11

Fore-after GRF (C) -0.009 0.01 0.02

Medial–lateral

GRF (OS)

-0.09 0.07 0.03 0.112a 0.58

Medial–lateral

GRF (C)

0.06 0.08 0.02

Medial–lateral

GRF (10–30 %)

(OS)

0.53 0.53 0.03 1.000 0.75

Medial–lateral

GRF (10–30 %)

(C)

0.48 0.49 0.01

Peak moment (OS) 1.29 1.27 0.08 0.979 0.69

Peak moment (C) 1.23 1.21 0.07

Stance phase (%)

(OS)

57.50 58.30 0.44 1.000 0.10

Stance phase (%)

(C)

58.50 58.92 0.48

Swing phase (%)

(OS)

42.50 41.76 0.46 1.000 0.10

Swing phase (%)(C) 41.50 41.07 0.48

First peak of vertical

GRF (OS)

9.75 9.85 0.16 1.000 0.75

First peak of vertical

GRF (C)

9.93 9.90 0.10

Second peak of

vertical GRD (OS)

10.13 10.03 0.20 1.000 0.11

Table 4 continued

Parameters Median Mean SD Priori

power

analysis

P value

Second peak of

vertical GRD (C)

10.39 10.29 0.12

Statistical significance at P \ 0.01 level, when compared with control

group

OS operated side (n = 14), C control group (n = 14)a Priori power of test is less than 0.500

Eur J Orthop Surg Traumatol

123

functional deficits [22]. Similar to previous studies, results

of our study demonstrated satisfactory outcomes for all

patients and there was a significant increase in AOFAS

scores for each patient [4, 6, 10]. Additionally, the most

commonly utilized clinical criteria for FAI include feelings

of giving way and insecurity [23]. In the long term, fre-

quency of ankle sprains decreased in all patients and

improvement of these objective and subjective criteria may

be directly related with the improved instability, and the

gait analysis supports these data in our study.

The foot progression angle was described by Nawata

et al. [24] as ‘‘the angle between progression line and

midline of the heel’’. According to that study, an increase

in adduction and supination was associated with decreased

foot progression angles. It is important to emphasize that

CAI patients had no significantly different-foot progression

angles on the operated side as compared with the uninjured

side during the stance phase, which has been suggested as

the point at which most inversion ankle sprains occur

(Fig. 1) [2]. This finding reveals that a previously reported

impairment of adduction-supination did not occur in our

patient group postoperatively.

Diminished range of motion was thought to be a pre-

disposing factor for lateral ankle sprains; indeed, many

authors have shown that a dorsiflexion deficit creates a

tendency toward hypersupination in CAI patients [25].

When compared with the contralateral uninjured side, there

was no significant difference between the groups (Fig. 1).

Wright et al. suggested that inversion and increased plantar

flexion enhance the risk of sprain injury [26]. The authors

also stated that restricted movement on the sagittal plane

increases the effect of bony structures in terms of providing

stability [26]. In sagittal kinematics, although there is no

significant difference, a slight dorsiflexion deficit and a

more plantar-flexed position was revealed from heel strike

until late mid-stance, without any significance (Fig. 1).

Among temporospatial parameters, double support time

was the only to show a significant difference. Despite the

Fig. 3 Vertikal (a), fore-after (b), and medial–lateral (c) ground reaction forces of operated and uninvolved sides (%BW)

Eur J Orthop Surg Traumatol

123

improved parameters of gait analysis, prolongation of

double support time may be caused by the effort to create a

more stable condition through compensation. However,

this entity was not supported by the other temporospatial

parameters.

GRF is a vector and has trajectories in all three planes.

Delahunt et al. reported that the posterior trajectory of GRF

was decreased in the FAI group in their kinetic analysis

[27]. In our study, the posterior trajectory of GRF was

more backward-oriented, and this may be explained by a

compensatory mechanism leading to a more stable ankle or

improved proprioception (Fig. 3). However, this insignifi-

cant difference may have occurred for other reasons, such

as a slow walking pace, posteriorly oriented center of

gravity, or high body mass index.

Delahunt et al. reported medially oriented GRF values,

which indicates more load at the lateral margin during the

loading phase of patients with FAI [16]. However, no

significant difference was observed in our patient group

during the loading phase (Fig. 3). Altered peroneal muscle

activity may explain the medially oriented GRF values and,

in therapeutic intervention, laterally supported insoles can

be used to correct the foot position, or peroneal muscle

strengthening may be included for proper load transfer.

One of the most important consequences of ankle

instability is joint degeneration. Although there is a lack of

information about the relation between joint degeneration

and isolated FAI, many authors have suggested that the

altered parameters of kinematics and kinetics due to FI may

lead to further damage to the structures of the ankle joint

[14, 18, 27]. Vertical GRF follows a characteristic ‘‘M’’

shape in the stance phase. The first peak is associated with

weight transfer and shock absorption. The second peak is

associated with the formation of impulse (Fig. 3). A higher

magnitude of vertical GRF leads to an increased supination

moment during initial contact [2]. However, no statistically

significant results were found between groups during the

first and second peak time periods. Additionally, Hin-

terman et al. reported that the incidence of cartilage dam-

age in patients with MI was 66 %, and individuals with

CAI demonstrated more articular cartilage defects due to

the rapid loading of the joint [8]. Brown et al. reported that

peak vertical GRF increased between 3 and 14 % in the

unstable ankle groups, and the time to peak vertical GRF

was 11–19 % faster in the unstable ankle as well [28]. In

our study, the mean peak vertical GRF and time to peak

vertical GRF do not show any significant differences; but

on the contrary, a mean reduction of 2.4 % was observed

on the involved sides. This finding may suggest a more

stable joint with a lack of rapid and altered loading and

may also clarify why none of the patients showed arthritic

changes, over the course of long-term follow-up. The

clinical relevance of our findings may impact joint health

for years to come. The results of gait analysis indicate that

the expected disturbances such as dorsiflexion deficit,

increased plantar flexion, and altered GRF parameters did

not occur significantly [25–27]. We attributed these

improvements to surgical intervention.

Although impingement and ankle instability are asso-

ciated pathologies, only 3 % of all inversion injuries result

in anterolateral soft tissue impingement [29]. In the study

of Urguden et al., successful arthroscopic treatment was

performed for soft tissue impingement in a group of

patients who experienced single or multiple inversion

injuries and pain [10]. The authors excluded other pathol-

ogies including osteochondral lesions, degenerative chan-

ges, and MI. Ventura et al. included a heterogeneous group

of chronic ankle instability patients with only positive

anterior drawer tests, excluding the presence of a talar tilt

test, and performed an arthroscopic four-step treatment

including synovectomy, debridement, capsular shrinkage,

and immobilization [11]. Berlet et al. adopted arthroscopic

thermal-assisted capsular modification for FAI patients,

though they did not suggest this technique for MI patients

[12]. Ferkel et al. performed synovectomy and debridement

of scar tissue for patients who experienced pain following

inversion injury with negative stress radiographs suggest-

ing the FI [6]. Gulish et al. evaluated the effectiveness of

arthroscopic debridement for the treatment of FI secondary

to intra-articular soft tissue impingement [7]. In most of

these studies, it is possible to observe the pathology of

hypertrophic synovitis and accompanying soft tissue

impingement problems. Thus, it appears that FI and soft

tissue impingement pathologies are more likely to be

encountered together. In our patient group, the leading

complaint was functional recurrent instability rather than

impingement syndrome, which mainly refers to chronic

pain. For the decision-making process of arthroscopic

partial synovectomy for FI, assessment of the main com-

plaint, evaluation of imaging studies, and exclusion of the

MI, and other intra-articular pathologies are mandatory.

While the deficits in ankle proprioception have been

attributed to damage of the joint capsule, ligaments, and

their associated mechanoreceptors; hypertrophic synovitis

may alter the mechanoreceptors of the ankle joint, leading

to an impaired ankle proprioception [4]. We provided relief

in FAI patients with arthroscopic partial synovectomy and

theorized that this would improve the proprioceptive and

neuromuscular deficits. Arthroscopic synovectomy allows

for treatment of the inflammation that results from the

underlying pathology. Also, excision of the synovitis,

debridement of the ATFL, and the scar tissue encourage

stimulation of the healing process of the surrounding cap-

sule [11, 12]. The clinical relevance of proprioceptive

deficits is not fully understood, but this healing process

may upregulate free sensory nerve endings, or by a motor-

Eur J Orthop Surg Traumatol

123

unit-related central mechanism which may lead to increase

the proprioception capacity. Further studies are essential to

confirm these suggestions.

There are strengths and limitations of our study that

should be noted: The strengths of this study are its long

follow-up period and homogeneous grouping of the

patients. As a limitation, several studies evaluated the

difference in FAI between injured subjects and healthy

controls using motion analysis [16–18, 21]. However, due

to nonparametric variability in gait data (possible varia-

tions in gait analysis due to gender, age, speed, and body

mass index), we preferred not to choose control subjects

from the normal population [30, 31]. Also, the absence of a

preoperative gait analysis of our patient group is another

limitation of our study, though in a very recent review,

Wikstrom et al. indicated that postural control deficits were

present on the uninvolved limb of patients with an acute

lateral ankle sprain, but not in patients with chronic ankle

instability [32]. They also encouraged researchers to

examine both the involved and uninvolved limb of CAI

patients relative to healthy controls. Therefore, we pre-

ferred to work on the same patients’ injured and contra-

lateral uninjured sides.

In conclusion, improved long-term clinical results and

scores were obtained in our patient group when compared

with the preoperative scores. Also, three-dimensional gait

analysis showed that the involved ankles demonstrate

similar gait patterns to the uninvolved ankles in patients

with FAI. We suggest arthroscopic synovectomy which is a

minimally invasive technique for the management of FAI

and associated impingement conditions.

Acknowledgments Authors would like to thank Shavkat Kuchimov

for his technical support during gait analysis.

Conflict of interest None.

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