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Management of chronic lateral ankle instability : alternatives for diagnosis and
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de Vries, J.S.
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de Vries, J. S. (2009). Management of chronic lateral ankle instability : alternatives for diagnosis and treatment
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Download date: 15 Jun 2017
- Chapter 4 -
Arthroscopic capsular
shrinkage for chronic ankle
instability with thermal
radiofrequency
- a prospective multicenter trial -
de Vries JS, Krips R, Blankevoort L, Fievez AWFM, van Dijk CN. Arthroscopic capsular
shrinkage for chronic ankle instability with thermal radiofrequency: Prospective multicenter
trial.
Orthopedics
2008;
31(7):
view.asp?rID=28896 (full article).
655
(abstract),
Epub:
www.orthosupersite.com/
Arthroscopic capsular shrinkage for chronic ankle instability
Abstract
The study was designed as a prospective multicenter longitudinal trial. Adult patients with
symptomatic mechanical chronic ankle instability, not improving with conservative therapy,
were included and operated on. The primary outcome measures were radiological and
manually tested mechanical laxity. Secondary outcome measures were number of
complications, re-operations and symptoms, range of motion, and functional (ankle) scores
(Karlsson and SF-36 score). The latest follow-up was 9 months for each patient.
Thirty-nine patients underwent surgery (19 male, 16 right ankles, median age: 27
years). Mechanical stability showed no clinically relevant improvement whereas most
secondary outcome measures showed a substantial and statistically significant improvement.
There was 1 operation related complication without functional consequences and three
patients underwent a secondary procedure. One was considered as a treatment failure,
requiring an open anatomic ligament reconstruction. The second patient sustained a severe
supination trauma by starting intensive training too early, also requiring an open anatomic
reconstruction. The third patient suffered from posterior ankle pain, which was successfully
treated by posterior ankle arthroscopy.
Arthroscopic thermal capsular shrinkage of the ankle is a safe procedure, leading to
resolution of symptoms in the majority of patients with chronic ankle instability.
101
Chapter 4
Introduction
Chronic ankle instability occurs in ten to twenty percent of the patients after an acute ankle
sprain.18 If conservative treatment fails and increased laxity of the lateral ankle ligaments is
present, a surgical stabilization of the ankle joint is indicated. Anatomical reconstruction of
the involved ligaments is the preferred method of treatment.22
Arthroscopic thermal capsular and ligament shrinkage is a new option for the
treatment of joint instability. The earliest reports about thermal capsular and ligament
shrinkage concern mainly animal and cadaver studies.9-11,24 Length reduction up to 60% has
been described but excessive heating leads to an increased potential for creep (deformation of
tissue under a constant load).11,26,37,38 Due to remodelling, this potential for creep diminishes
in two to three months but warrants careful rehabilitation in the early postoperative period.
Most clinical experience exists with thermal capsular shrinkage of the glenohumeral
joint capsule for shoulder instability. Initial results were promising but a recent prospective
trial with the longest (mid-term) follow-up period thus far, showed a failure rate in more than
one-third of the patients, probably due to recurrence of capsular laxity.4
The ankle joint is intrinsically more stable compared to the shoulder due to its bony
congruency and is therefore more appropriate for the application of arthroscopic thermal
capsular shrinkage in case of increased capsular and ligament laxity. Five retrospective
studies on the treatment of chronic ankle instability with capsular shrinkage have been
published, showing good results in the vast majority of patients at up to 2.5 years followup.2,3,14,25,29
Potential advantages of the procedure, compared to an open procedure, are the
minimally invasiveness, reduced operating time, outpatient setting, less surgical morbidity,
fast recovery and quick return to work and sports. A more extensive prospective clinical study
is required to determine the efficacy of arthroscopic thermal shrinkage in chronic ankle
instability in a general population.
The aim of this prospective study was to assess the mechanical and clinical benefit,
including proprioception, of nonablative thermal capsular shrinkage by application of
radiofrequent energy to the lateral ankle-joint capsule and ligaments to determine if normal
ankle laxity and functional ankle stability would be restored.
102
Arthroscopic capsular shrinkage for chronic ankle instability
Materials and Methods
Study design
The study was designed as a prospective longitudinal multicenter trial. Eight centers
participated. In each center 1 surgeon, experienced in ankle arthroscopy, performed the
operations. The Medical Ethical Review Board of all centers approved of the study, and
participating patients gave written informed consent. The study period from first inclusion to
last follow-up was from February 2002 until February 2005.
Patients
Patients were selected from the outpatient clinic. Chronic ankle instability was defined as
recurrent sprains or giving way for more than six months after an acute ankle sprain, in spite
of a period of conservative treatment.18 Specific inclusion criteria were: adult patients (! 18
years of age), who were able to give informed consent and had chronic ankle instability with
increased mechanical laxity.
Increased mechanical laxity was defined as a positive anterior talar translation or talar
tilt on stress radiographs using the Telos-stress apparatus, with anterior talar translation ! 4
mm or a difference with the ipsilateral side ! 3 mm and talar tilt !10o and "15o or a difference
with the ipsilateral side ! 6o. A talar tilt >15o was considered an exclusion criterion since it
was assumed to represent multiple ligament laxity.
Additional exclusion criteria were: previous operative therapy for chronic ankle
instability, constitutional hyper laxity, systemic diseases affecting the locomotor system and
osteoarthritis grade II or III.36
Sample size
An estimate of the required sample size was calculated from mean values with standard
deviations (SD) for improvement of the anterior talar translation and talar tilt found in the
literature.17,29 An average decrease in anterior talar translation of 3 mm, SD 2.6, or a decrease
in talar tilt of 30, SD 3.8, was considered to be clinically relevant. Given an ! of 0.05 and a
power of 0.9, the required number of patients was 16 for anterior talar translation and 34 for
talar tilt.
103
Chapter 4
Surgical procedure
The operation was performed in an outpatient setting according to a standardized procedure.
The procedure was captured on video to share with the surgeons of the participating centers.
Figure 1 – Arthroscopic image of anterolateral side of the ankle joint with an indication of
the fibula, tibia and the course of the anterior talofibular ligament that is part of the joint
capsule. The shrinkage procedure is performed by moving the active radiofrequency probe
over the anterior talofibular ligament and adjacent capsule. Abbreviations: ATFL, anterior
talofibular ligament; RF, radiofrequency.
The patient was placed in a supine position. Anteromedial and lateral portals were made by
stab incisions. A 4.0 mm arthroscope was introduced through the medial portal and the
instruments were introduced through the lateral portal. Initially, treatment of additional
pathology such as removal of osteophytes, synovitis or a loose body was performed.
Intraoperative testing of the ankle instability was performed. Shrinkage was performed by
104
Arthroscopic capsular shrinkage for chronic ankle instability
application of radiofrequent energy (figure 1), using an arthroscopic probe with a 3.5 mm
side-effect tip, mode V1 (Vapr®, Depuy Mitek, Amersfoort, NL). The initial energy level was
20 watt, but could be adjusted to a maximum of 50 watt. In all patients shrinkage of the ATFL
and adjacent joint capsule was performed. A standard operation report was written for all
patients, with registration of the operation time.
Rehabilitation
Postoperatively, a compression bandage was applied for 3 to 5 days, during which patients
were advised to rest and avoid weight bearing. After application of an inelastic tape bandage,
patients were allowed to mobilise with full weight bearing as tolerated. The tape was replaced
every 2 weeks over a 6-week period. During this period patients were allowed to resume work
as tolerated, but were restricted from participating in activities with a high risk of spraining
the ankle. In the following 6 weeks patients were allowed to resume sports as tolerated.
Outcome measures
At inclusion patient’s characteristics were registered. The primary outcome measure was
difference in pre- and postoperative mechanical laxity measured with ankle stress radiographs
(anterior talar translation and talar tilt) and the manual anterior drawer test.35 Secondary
outcome measures were: subjective instability, pain, subjective and objective swelling, ankle
joint stiffness, range of motion, time to return to work and sports, changes in level or
abandoning of work and sports, ankle (Karlsson), sports (Tegner) and general (SF-36)
functional scores, patient satisfaction, operation time, and number, nature and severity of
complications.16,33,40 Limited range of motion was defined as >50 negative difference with the
contralateral side.
An additional outcome measure was balance, as a measure of proprioception, assessed
by a one-leg stance test.15 Patients were instructed to stand on 1 leg on a compliant floor (eg,
gymnastics mat) for 1 minute. When loosing balance, defined as touching the floor with the
contralateral foot, the patients had to resume their position and continue until 1 minute was
completed. Four conditions were tested preoperatively and at 6-months follow-up: left and
right leg, both with eyes open and eyes closed. The time until the first balance disturbance
and the total number of disturbances were registered.
105
Chapter 4
Follow-up
All patients were evaluated preoperatively, at 6 weeks and 6 and 9 months postoperatively. At
6 weeks and 9 months, the outcome measures were taken by questionnaires alone. At 6
months measures of outcome were taken by questionnaires, physical examination, stress
radiographic assessment, and the balance test was performed.
Data analysis
Data were entered into a personal computer and analyzed using SPSS 11.5 for Windows. Preand postoperative values were compared. Due to the skewed distribution of most data,
continuous data are presented as median with a range and non-parametric statistical tests were
used for analysis: the Wilcoxon signed ranks test for continuous data and the McNemar chisquare test for dichotomous data. Statistical significance level was determined at p<0.05.
106
Arthroscopic capsular shrinkage for chronic ankle instability
Results
Thirty-nine patients (19 male, 20 female; 16 right, 23 left ankles) were included. The median
preoperative duration of symptoms was 4 years (range, 0.5-30 years). The median patient age
at the time of operation was 27 years (range, 18-66 years). No patients were lost to follow-up.
One female patient did not allow radiographic stress evaluation at 6-months follow-up
because of anticipated pain, but the 9-months follow-up was completed. At 9 months, 28
patients (72%) rated the result of the operation as good (33%) or excellent (39%), 9 (23%) as
fair, and 2 (5%) as poor.
Operation
Median operation time was 24 minutes (range, 6-47 minutes). In 30 of the 39 patients (77%),
excessive synovitis or scar tissue in the lateral aspect of the ankle was present. Synovectomy
or debridement of the lateral side of the ankle joint was performed in all patients.
Complications and re-operations
Complications were seen in seven patients (18%). One postoperative complication occurred:
injury to a branch of the superficial peroneal nerve, possibly caused by the incision for the
lateral arthroscopic portal. The subsequent numbness of the lateral foot had not resolved at
final follow-up, but the patient did not suffer from functional limitations and had no
complaints.
Three patients were scheduled for re-operation at the closure of the study, of which 1
was related to the study intervention. Two patients had symptoms of giving way at 9-months
follow-up. One of which was a triathlon athlete who started training 4 weeks after the initial
operation and sustained a new severe ankle inversion injury in which the lateral ankle
ligaments were torn. The second patient had persistent instability and laxity with a sedentary
activity level. Both patients were scheduled for an open anatomic ligament reconstruction.
The third patient had posterolateral ankle pain due to a posterior impingement syndrome.
Preoperatively, posterolateral pain symptoms were already recognized but it was decided to
only perform the ligament reconstruction. It was expected that better mechanical stability
would decrease the posterior impingement symptoms. The stability had improved but the
posterior symptoms remained. He was successfully treated by posterior ankle arthroscopy.
107
Chapter 4
Two patients developed an allergy to the tape. In 1 patient the tape was replaced by an elastic
bandage and in the second patient the tape was removed after four weeks and then replaced by
an elastic bandage. One patient had prolonged postoperative pain at the anterolateral side of
the ankle joint. The pain was still present at 9-months follow-up, but the intensity of the pain
had significantly decreased.
P=0.036§
Figure 2 - Radiographically determined effect of thermal shrinkage of the anterolateral ankle
capsule, including the anterior talofibular ligament, on the mechanical stability, preoperative
and 6 months postoperative. The solid line is the median, the box represents the interquartile
range, the error bars the 95% range, and the asterisks indicate the extremes. Abbreviations:
TT = talar tilt (degrees); ATT = anterior talar translation (mm). §Wilcoxon signed ranks test.
Mechanical laxity
Radiographically and manually tested increased laxity was present in all patients at the time
of inclusion. The difference between radiographically measured preoperative and 6 months
108
Arthroscopic capsular shrinkage for chronic ankle instability
postoperative anterior talar translation, in favour of the postoperative result, was statistically
significant (p=0.036, figure 2). No preoperative - and postoperative difference was found for
the talar tilt (figure 2). One patient did not allow for postoperative ankle stress radiographs
and was excluded from this part of the analysis.
At 6-months follow-up, a reduction of mechanical laxity as judged by the manual
anterior drawer test was seen in 20 patients. Twenty-six patients still had a positive anterior
drawer test. The difference with the preoperative number of patients (all patients positive
anterior drawer test) was statistically significant (p=0.001). Deterioration was not seen in any
of the patients.
Figure 3 - Pre- and postoperative number of patients with symptoms. *McNemar chi-square
test.
Symptoms and Functional outcome
The number of patients with subjective instability, pain and swelling had significantly
diminished at follow-up (figure 3). The decrease in number of patients with limited capacity
for stair climbing, running, work or sports was less sharp but statistically significant for all
parameters at most recent follow-up (figure 4). At 9 months, running was limited in 20
patients, a significant increase of 15 patients compared to 6-months follow-up.
109
Chapter 4
Figure 4 - Pre- and postoperative number of patients with functional limitations during stair
climbing, running, work and sports. *McNemar chi-square test.
Most patients reported they performed work (37 patients) and participated in sports (36
patients) at the same or a higher level than before the operation. Three patients reported they
participated in sports at a lower level. The median time to return to work was 3 weeks (range,
1-8 weeks). Median time to return to sports was 9.5 weeks (range, 2-36 weeks).
The number of patients with pain on physical examination had significantly decreased
at 6-months follow-up (30 versus 14 patients, p<0.001). Swelling was pre- and
postoperatively present in 4 patients (only 1 patient had pre- and postoperative swelling). Preand postoperative sagittal range of motion did not differ significantly. At 6-months follow-up,
2 patients had a limited range of motion: respectively 100 and 150 less compared to the
contralateral side.
When compared to the preoperative score, the median Karlsson and Tegner score had
increased significantly at all follow-up periods (table 1, figure 5). According to the Karlsson
score, 27 patients had a good or excellent result (74%) and 1 patient a poor result (3%). The
Tegner score at 9 months showed a significant improvement compared to the score at 6
months (table 1).
110
Arthroscopic capsular shrinkage for chronic ankle instability
Table 1 - Pre- and postoperative Tegner-score
Median (range)
p-value*
Preoperative
3 (0-9)
n/a
6 weeks
2 (0-7)
n/a
6 months
4 (1-7)
0.011
9 months
4 (1-9)**
<0.001
*compared to preoperative, **p=0.004, compared to 6 months, both Wilcoxon signed ranks test
p<0.001*
Figure 5 - Pre- and postoperative Karlsson-scores. The solid line is the median, the boxes
represent the interquartile range, and the error bars indicate the 95% range. *Wilcoxon signed
ranks test
111
Chapter 4
p<0.001§
Figure 6 - SF-36 - Preoperative and 6 months postoperative scores of the Standardized
Physical and Mental Component Scales. The solid line is the median, the boxes represent the
interquartile range, the error bars the 95% range, and the asterisk indicates the extremes.
§
Wilcoxon signed ranks test.
Table 2 - SF-36 score: the result according to the 8 domains. Postoperative data were
acquired at six months follow-up.
PF
RP
BP
GHP
V
SF
RE
MH
Preoperative
range
median
25-100
75
0-100
75
21-100
62
25-100
72
20-95
65
38-100
75
0-100
100
48-96
80
Postoperative
range
median
25-100
95
0-100
100
51-100
80
35-100
77
20-100
70
50-100
100
0-100
100
48-100
80
p-value*
p<0.001
p=0.004
p<0.001
p=0.077
p=0.133
p=0.007
p=0.051
p=0.221
*Wilcoxon signed ranks test. PF: physical functioning, RP: role physical, BP: bodily pain, GHP: general health
perception, V: vitality, SF: social functioning, RE: role emotional, MH: mental health.
112
Arthroscopic capsular shrinkage for chronic ankle instability
Proprioception
Thirty-five of the 39 patients performed the balance test. Four patients were not tested at the
start of the study because the facilities were not yet available. Two patients were not able to
perform the test with eyes closed and in 1 patient the pre-operative values of ‘time to first
balance disturbance’ were not registered.
Figure 7 – One-leg stance test of the affected leg: preoperative and 6 months postoperative
‘time to first balance disturbance’ (timepre and timepost) with eyes open en eyes closed. The
solid line is the median, the boxes represent the interquartile range, and the error bars indicate
the 95% range. §Wilcoxon signed rank test.
Analysis of the affected leg showed a significant difference between pre- and 6 months
postoperative values for ‘time to first disturbance’ with eyes closed and for the ‘number of
balance disturbances’ with both eyes open and closed, whereas for the healthy leg none of the
differences was significant (table 3, 4; figure 7, 8).
113
Chapter 4
Table 3 - One-leg stance test: ‘time to first balance disturbance’. Postoperative data were
acquired at 6 months follow-up.
Eyes open
Eyes closed
preop*
postop*
p-value**
Both legs
50 (1-60)
60 (3-60)
0.03
3 (1-35)
5 (1-45)
0.06
Affected leg
42 (1-60)
56 (3-60)
0.08
3 (1-11)
5 (1-16)
0.008
Healthy leg
58 (2-60)
60 (5-60)
0.20
3 (1-35)
4 (1-45)
0.94
0.32
0.84
0.11
0.50
p-value***
preop*
postop*
p-value**
*median (range), **Wilcoxon signed ranks test, ***for difference between legs, Wilcoxon signed ranks test
Figure 8 – One-leg stance test of the affected leg: Preoperative and 6 months postoperative
‘number of balance disturbances of the affected leg’ (ratepre and ratepost). The solid line is
the median, the boxes represent the interquartile range, and the error bars indicate the 95%
range. §Wilcoxon signed ranks test.
114
Arthroscopic capsular shrinkage for chronic ankle instability
Comparing the affected leg with the healthy leg, the preoperative differences for the ‘number
of disturbances’ in both the eyes open en eyes closed condition were significant, whereas the
postoperative differences were not (table 4). The pre- and postoperative differences for the
‘time to first disturbance’ with eyes open and closed were not significant (table 3).
Table 4 - One-leg stance test: number of balance disturbances during 1 minute. Postoperative
data were acquired at 6 months follow-up.
Eyes open
Eyes closed
preop*
postop*
p-value**
preop*
postop*
p-value**
Both legs
1 (0-27)
0 (0-18)
<0.001
14 (1-37)
12 (3-30)
0.046
Affected leg
1 (0-27)
1 (0-18)
0.002
16 (2-37)
13 (3-28)
0.009
Healthy leg
1 (0-15)
0 (0-14)
0.09
13 (1-27)
12 (3-30)
0.92
0.009
0.44
0.001
0.88
p-value
*median (range), **Wilcoxon signed ranks test, ***for difference between legs, Wilcoxon signed ranks test
115
Chapter 4
Discussion
This multicenter prospective longitudinal study was conducted to evaluate the effect of
arthroscopic thermal capsular and ligament shrinkage on chronic lateral ankle instability.
Subjective stability had improved in the majority of patients at follow-up. Mechanical laxity
reduction was small but statistically significant for anterior talar translation but not for talar
tilt. The primary outcome measure was radiographically and manually tested mechanical
stability. The improvement of the radiographic anterior talar translation, although statistically
significant, is considered clinically of less relevance, in accordance with the beforehandspecified difference of 3 mm used for sample size calculation. The result of manual anterior
drawer test showed a similar statistical significant effect. An important finding was a
substantial and statistically significant improvement of almost all secondary outcome
measures at follow-up, compared to the preoperative scores. Additionally, 72% of the patients
rated the outcome as good or excellent. This functional improvement correlated with the
significant improvement seen with the balance test of the affected leg, indicating better
postoperative proprioception.
Four reports on thermal capsular shrinkage for chronic ankle instability have been
published since the study by Ollof et al.2,3,14,25,29 These 4 studies all have follow-up periods
longer than the current study. The strength of this series as compared to these reports is its
prospective multicenter design, the larger group representing a normal population, and that no
patients were lost to follow-up. The functional improvement is in accordance with the other
studies on shrinkage for chronic ankle instability. In 3 of the 5 studies a marked improvement
of radiographic mechanical stability is reported as well.2,3,14
An explanation for the difference in improvement of mechanical stability might be
that in the other studies the operated ankles were immobilized in a cast for 2 to 6 weeks,
whereas rehabilitation in this study was functional and ambulation with full weight bearing as
tolerated was allowed as soon as 5 to 7 days postoperatively. Although early functional
rehabilitation may seem to contradict with the initial potential for creep (deformation of tissue
under a constant load) with a possible relapse of ligament laxity, an animal study showed that
early mobilisation of thermally treated ligaments enhances remodelling of ligament tissue and
even diminished the potential for creep compared to immobilization.5,39 Avoiding high-risk
activities, the tape is thought to provide sufficient support to prevent for re-spraining the ankle
116
Arthroscopic capsular shrinkage for chronic ankle instability
in the early postoperative period. The functional rehabilitation program was chosen to allow
for early return to normal daily activities, an advantage of arthroscopic procedures in general.
Another explanation for the lack of substantial reduction of ligament laxity might be that the
preoperative increased mechanical laxity in this study was less marked than in other studies,
with less room for improvement.3,25,29
Apart from improvement in mechanical laxity, there are alternative explanations for
the functional improvement. The functional improvement could be the improved
proprioception as caused by the surgical procedure. The relation between proprioception and
functional ankle stability with or without mechanical stability in general has been pointed out
by several authors.1,12,13,15,34 The influence of surgical procedures for chronic instability on
proprioception is less extensively evaluated. Larsen et al and Rosenbaum et al found
postoperative improved peroneal electormyogram activity, as compared to preoperative
measurements.23,31 More recently, Halasi et al reported improved joint position sense after
surgical stabilization.8
The mechanism responsible for the improved proprioception in this study could be the
thermal changes of mechanoreceptors in the lateral capsule and ligaments although their
contribution to proprioception is unclear.21,27,28,30,32 Konradsen et al found, after injection of
the lateral ankle ligaments with a local anaesthetic, that active joint position sense was
unaffected but passive joint position sense was disturbed.21 It is suggested that this might
influence correct placement of the foot during walking, making patients prone to sprains.
Myers and Riemann et al found that injection of the lateral ankle ligaments with both a local
anaesthetic and a placebo led to a decreased ‘muscle protective response’ measured with
electromyography.28 This implies that the edema caused by the injection, and not the
anaesthetic, is responsible for the altered proprioception.
Local tissue swelling and edema being the cause of altered proprioception is in
accordance with a second possible explanation for altered sensory input: the removal of intraarticular pathologic soft tissue. In order to get access to the anterior talofibular ligament for
thermal shrinkage, debridement of the synovial tissue of the anterolateral ankle joint was
performed in all of the patients. Abundant pathologic tissue in the lateral gutter might lead to
soft tissue impingement and disturbed proprioceptive function, leading to symptoms of
recurrent giving way. This theory is supported by a study reporting the presence of
anterolateral impingement lesions in two-thirds of 61 patients in whom the lateral ankle joint
was inspected during ligament reconstruction for chronic ankle instability.6
117
Chapter 4
An important question is how arthroscopic capsular shrinkage for chronic ankle instability
compares to open reconstructions of the lateral ankle ligaments. Karlsson et al reported 7790% good and excellent results according to the Karlsson score in a randomized trial
comparing two anatomical reconstructions with preoperative severe functional instability with
mechanical laxity and a minimum follow-up of 2 years.17 Maiotti et al reported 86% good and
excellent results after arthroscopic capsular shrinkage for chronic ankle instability in 22
soccer players at a minimum of 2.5 years follow-up, whereas this study showed 69% good
and excellent results in 39 patients at a minimum of 9 months follow-up.25 In both this and
Maiotti’s study the ankle score used by Karlsson was applied, making the results comparable.
Considering the potential for creep seen in biomechanical studies, shrinkage at
temperatures higher than 65o to shorten the ligaments > 20% to 30% cannot be recommended.
This makes thermal capsular shrinkage, in theory, less appropriate for severe mechanical
instability. However, Maiotti et al reported 55% reduction of radiographic anterior talar
translation and even 80% reduction of talar tilt after shrinkage for chronic ankle instability.25
This is even a greater reduction than reported by Karlsson et al for anatomic reconstructions
(30% to 44% reduction of talar tilt and anterior talar translation).17
A possible advantage of the shrinkage procedure is the short operative time. In our
series the mean operation time was 27 minutes (SD 10.3). In the study by Karlsson, the mean
operation time for the anatomic reconstruction with the Karlsson modification (35 minutes
(SD 11)) and the Brostrom modification (44 minutes (SD 6)) were substantially longer.17
An advantage of arthroscopy is the short rehabilitation time required for most
procedures. In this study, patients were advised about return to previous activities according
to rather liberal guidelines: return to work in 6 weeks, and return to sports in 12 weeks. The
median time to return to work in this study compares favourably to the rehabilitation period
reported by Karlsson in two randomized trials about rehabilitation after an anatomic
reconstruction (a mean of 6.0 to 8.5 weeks versus a mean of 4.0 weeks in our study).19,20 The
less marked difference in time to return to sports might be explained by the supervised
rehabilitation program that all patients in the studies by Karlsson et al underwent. In the
current study there was no supervised rehabilitation program.
The total number of complications in this study (7 in 39 patients, 18%) was high.
However, 2 (5%) were minor complications related to the after treatment (allergy to tape) that
resolved with simple measures. There was only 1 (3%) surgery related complication (ie,
damage to a branch of the superficial peroneal nerve in 1 patient that did not lead to
118
Arthroscopic capsular shrinkage for chronic ankle instability
functional impairment at final follow-up). This percentage of surgery-related complications is
much lower than other reports in literature. In a review, Ferkel reported a 9% complication
rate with ankle arthroscopy and Karlsson et al found 10% surgery-related complications in the
randomized trial comparing different reconstructions.7,17 None of the patients in the shrinkage
study had wound healing problems.
All 3 re-interventions were marked as late complications, but only 1 (persisting
instability without a severe recurrent sprain) can be considered as a treatment failure. The
second patient with recurrent instability sustained a severe re-injury before the sixth
postoperative week due to early return to intensive training activity. This was not in
accordance with the advised rehabilitation scheme and can be considered a protocol violation.
Exclusion of this patient does not affect statistical significance of radiographic mechanical
laxity measures. The third patient had unrelated posterolateral ankle pain, which was
successfully treated with posterior ankle arthroscopy.
Conclusions
Thermal arthroscopic capsular and ligament shrinkage for chronic lateral ankle instability is a
safe procedure that requires limited operation time and results in a high percentage of good
and excellent clinical results with a significant functional improvement. Since the reduction of
mechanical laxity was only moderate, debridement of the synovial tissue in the anterolateral
part of the ankle joint may have led to better proprioception and ankle coordination.
119
Chapter 4
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