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A test battery for evaluating hop performance in patients with an ACL injury and patients who have undergone ACL reconstruction

Authors:
  • NEETER FYSIOTHERAPIE, Amsterdam, Netherlands

Abstract and Figures

The purpose of this study was to develop a test battery of hop tests with high ability to discriminate (i.e. high test-retest reliability, sensitivity, specificity and accuracy) between the hop performance of the injured and the uninjured side in patients with an ACL injury and in patients who have undergone ACL reconstruction. Five hop tests were analysed: three maximum single hop tests and two hop tests while developing fatigue. Fifteen healthy subjects performed the five hop tests on three separate occasions in a test-retest design. Thirty patients, mean 11 months after an ACL injury and 35 patients, mean 6 months after ACL reconstruction were tested. ICC values ranged from 0.85 to 0.97 for the five hop tests, indicating that all the tests had high test-retest reliability. Sixty-seven percent to 100% of the healthy subjects had normal symmetry (i.e. <10% side-to-side difference) in the five hop tests. Abnormal symmetry in the five hop tests ranged from 43 to 77% for patients with an ACL injury and from 51 to 86% for patients who had undergone ACL reconstruction respectively. The three tests with the highest ability to discriminate hop performance were chosen for the test battery; they were the vertical jump, the hop for distance and the side hop. The test battery revealed a high level of sensitivity and accuracy in patients with an ACL injury (87 and 84%) and in patients who had undergone ACL reconstruction (91 and 88%), when at least one of the three tests was classified as abnormal. To summarise, the test battery consisting of both maximum single hop performances: the vertical jump and the hop for distance and hop performance while developing fatigue: the side hop, produced high test-retest reliability, sensitivity and accuracy. Further, the test battery produced higher values compared with any of the three hop tests individually revealing that only one out of ten patients had restored hop performance 11 months after an ACL injury and 6 months after ACL reconstruction. It is concluded that this test battery showed a high ability to discriminate between the hop performance of the injured and the uninjured side both in patients with an ACL injury and in patients who have undergone ACL reconstruction.
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Alexander Gustavsson
Camille Neeter
Pia Thomee
´
Karin Gra
¨
vare Silbernagel
Jesper Augustsson
Roland Thomee
´
Jon Karlsson
A test battery for evaluating hop performance
in patients with an ACL injury and patients
who have undergone ACL reconstruction
Received: 14 February 2005
Accepted: 9 August 2005
Published online: 9 March 2006
Springer-Verlag 2006
Abstract The purpose of this study
was to develop a test battery of hop
tests with high ability to discriminate
(i.e. high test–retest reliabili ty, sen-
sitivity, specificity and accuracy)
between the hop performance of the
injured and the uninjured side in
patients with an ACL injury and in
patients who have undergone ACL
reconstruction. Five hop tests were
analysed: three maximum single hop
tests and two hop tests while devel-
oping fatigue. Fifteen healthy sub-
jects performed the five hop tests on
three separate occasions in a test–
retest design. Thirty patients, mean
11 months after an ACL injury and
35 patients, mean 6 months after
ACL reconstruction were tested.
ICC values ranged from 0.85 to 0.97
for the five hop tests, indicating that
all the tests had high test–retest
reliability. Sixty-seven percent to
100% of the healthy subjects had
normal symmetry (i.e. <10% side-
to-side difference) in the five hop
tests. Abnormal symmetry in the five
hop tests ranged from 43 to 77% for
patients with an ACL injury and
from 51 to 86% for patients who
had undergone ACL reconstruction
respectively. The three tests with the
highest ability to discriminate hop
performance were chosen for the test
battery; they were the vertical jump,
the hop for distance and the side
hop. The test battery revealed a high
level of sensitivity and accuracy in
patients with an ACL injury (87 and
84%) and in patients who had
undergone ACL reco nstruction (91
and 88%), when at least one of the
three tests was classified as abnor-
mal. To summarise, the test battery
consisting of both maximum single
hop performances: the vertical jump
and the hop for distance and hop
performance while developing fati-
gue: the side hop, produced high
test–retest reliability, sensitivity and
accuracy. Further, the test battery
produced higher values compared
with any of the three hop tests indi-
vidually revealing that only one out
of ten patients had restored hop
performance 11 months after an
ACL injury and 6 months after ACL
reconstruction. It is concluded that
this test battery showed a high abil-
ity to discriminate between the hop
performance of the injured and the
uninjured side both in patients with
an ACL injury and in patients who
have undergone ACL reconstruc-
tion.
Keywords Anterior cruciate
ligament Æ Knee Æ Rehabilitation Æ
Hop test
DOI 10.1007/s00167-006-0045-6
Knee Surg Sports Traumatol Arthrosc
(2006) 14: 778–788
SPORTS MEDICINE
A. Gustavsson Æ C. Neeter
P. Thomee
´
Æ K. Gra
¨
vare Silbernagel
J. Augustsson Æ R. Thomee
´
Æ J. Karlsson
Department of Orthopaedics,
Sahlgrenska University Hospital,
Go
¨
teborg University, Go
¨
teborg, Sweden
A. Gustavsson Æ C. Neeter
P. Thomee
´
Æ K. Gra
¨
vare Silbernagel
J. Augustsson Æ R. Thomee
´
Sportrehab Physical Therapy and Sports
Medicine Clinic, Go
¨
teborg, Sweden
A. Gustavsson (&)
Department of Orthopaedics, Lundberg
Laboratory for Human Muscle Function
and Movement Analysis, Sahlgrenska
University Hospital, 413 45 Go
¨
teborg,
Sweden
E-mail:
alexander.gustavsson@orthop.gu.se
Tel.: +46-31-426891
Fax: +46-31-416816
Introduction
One difficult challenge in the rehabilitation of anterior
cruciate ligament (ACL) injury and reconstruction is to
determine when it is safe to return to strenuous physical
activities. Single-leg hop tests are commonly used to
evaluate functional performance after an ACL injury
[17] or reconstruction [819]. To some de gree, hop tests
have been able to discriminate between the hop perfor-
mance of the injured and uninjured side in patients with
an ACL injury and between controls and patients [1, 2,
4, 7, 10]. There is also some evidence that single-leg hop
tests are important when trying to predict whether pa-
tients will have future difficulty in terms of recurrent
knee instability after an ACL injury [3].
The ratio between the involved and uninvolved leg
has been the most frequently reported criterion for
determining normal or abnormal hop test scores [16,
810, 13, 15, 1721]. It has been suggested that the
normal ratio in healthy subjects is greater than or equal
to 85% [1, 21] or 90% [10, 20].
Several hop tests are described in the literature,
including various single-leg hop tests for distance, time
[16, 811, 1321] and height [1 , 13, 15, 20, 21]. The
evaluation of functional outcome after an ACL injury
is often limited to only one test, the single-leg hop for
distance [9, 14, 17, 18]. However, the reported sensi-
tivity for detecting functional limitations associated
with ACL deficiency with the single-leg hop for dis-
tance test is relatively low, ranging from 38 to 52%
[4, 5, 7]. Noyes et al. [5] combined two horizontal hop
tests, a single-leg hop for dista nce and a timed hop in
order to increase the sensitivity. Itoh et al. [4] argued
that hop tests should involve more twisting and cutting
movements and evaluated the figure-of-eight hop test,
the up–down hop test and the side hop test. When
these three tests and the single-leg hop for dista nce test
were combined in a test battery, a sensitivity of 82%
was obtained. Sports injuries often tend to occur at the
end of a sporting event, when a participant is fati gued
[2224]. None of the tests recommended by either
Noyes et al. [5] or Itoh et al. [4] is, however, per-
formed under fatigued conditions. Augustsson et al. [8]
reported an improved sensitivity level when testing hop
performance under fatigued conditions. All patients in
the study by Augustsson et al. [8] were classified,
11 months after ACL reconstruction, as having normal
hop capacity when performing a single leg hop for
distance non-fatigued. After a fatiguing quadriceps
muscle exercise only one-third of the patients were
classified as having normal hop performance.
The purpose of this study was to develop a test battery
of hop tests with a high ability to discriminate (i.e. high
test–retest reliability, sensitivity, specificity and accuracy)
between the hop perfo rmance of the injured and the
uninjured side in patients with an ACL injur y and in
patients who have undergone ACL reconstruction.
We hypothesise that a test battery evaluating different
hop qualities, i.e. maximum single hop performance, as
well as hop performance while developing fatigue, will
increase the opportunity to detect discrepancies in hop
performance (i.e. increase the test sensitivity) compared
with using only a single hop test.
Materials and methods
Subjects
Three groups of subjects participated in this study,
healthy individuals, patients with an ACL injury and
patients who had undergone ACL reconstruction.
The patients physi cal activity levels prior to their
ACL injury and at the test occasion were documented
using the Tegner score [25]. The Tegner score is an
activity grading scale, where activities of daily living,
recreation, competitive sports and work are graded
numerically from 1 to 10. One represents the least
strenuous knee activity and ten is hard strenuous knee
activity such as rugby and international soccer. The
score was modified in the year 2000 but this version has
not been published. The modified version was used in
the present study with the permission of the authors. To
complement the Tegner score with the subjects’ intensity
and frequency in participation in physical activity a four
grade physical activity scale was constructed, using a
validated score for elderly people [26] as a model. After
discussions in an expert group consisting of experienced
physical therapists and orthopaedic surgeons good face
validity of the new physical activity scale was assured.
On the physical activity scale the subjects made their
own judgment on how vigorously and frequent they
participated in physical activity at the present time as
well as prior to their knee injury. The four grades in this
physical activity scale were:
1. Hardly any physical activity at all.
2. Light physical activ ity a few hours a week.
3. Somewhat strenuous physical activity 2–3 h a week.
4. Hard strenuous physical activity on a regular basis.
A convenience sample of nine male and six female
healthy subje cts were recruited. The subjects had no
history of back, hip, knee or ankle dysfunction and were
tested on three separate occasions in a test–retest design.
Thirty patients, 18 males and 12 females, with an
ACL injury were tested. An interval of 4–44 months
elapsed between the index knee injury and the test
occasion. The inclusion criteria consisted of a positive
anterior drawer and Lachman’s test, performed by
779
experienced orthopaedic surgeons and verified by the
patient’s physiotherapist, history of knee injury and
subjective giving way, no acute pain or swelling and no
prior surgical procedu re in either leg.
Thirty-five patients, 25 males and 10 females, who
had undergone ACL reconstruction, were tested. The
patients were included in this study if they met the
following criteria, no acute pain or swelling and no
prior surgical procedure in either leg. The operated
patients were tested 6 months after ACL reconstruc-
tion. Descriptive data for all subjects are presented in
Table 1.
All patients in this study were recruited from the
same physiotherapy clinic and underwent supervised
physiotherapy according to a criterion based protocol.
The patients trained two to three sessions per week
(initially combined with a home based program). Wet-
vest training and functional group training were offered
as additional sessions. Full immediate weight bearing
was allowed post operatively. Early range of motion
exercises was encouraged. Both closed and open kinetic
chain exercises were used to restore muscle strength of
lower extremity muscles. Also neuromuscular training
(balance, proprioception and plyometric exercises) were
incorporated with gradually increased load and com-
plexity.
Prior to any testing, written informed consent forms
were signed by all the participants. Approval for the
study was obtained from the Human Ethics Committee
at Go
¨
teborg University, Sweden.
Procedure
The healthy subjects performed five single-leg hop tests
in both legs at three different test sessions in a test–retest
design. An interval of 3–13 days elapsed between test
occasion 1 and 2 and an interval of 3–19 days between
test occasion 2 and 3. Subjects were asked not to par-
ticipate in strenuous physical activities the day before
testing. For the healthy subjects, the order of the tests
and the leg that was first tested were randomised,
whereas the test order was pre-determined for the pa-
tients. The patients performed the tests in the same order
as they are presented. The practice and test trials were
performed using the uninjured leg first, followed by the
injured leg. The patients were thoroughly familiarised at
the physiotherapy clinic prior to the test session. All the
tests were supervised by the same test leader. Verbal
encouragement was used and athletic footwear were
standardised.
Before testing, the subjects completed a warm-up
consisting of 5 min of stationary cycling, two times 10
squats, two times 10 toe rises and warm-up jumps.
The following single-leg hop tests were used: (1) ver-
tical jump, (2) hop for distance, (3) drop jump followed
by a double hop for distance, (4) square hop and (5) side
hop. The tests were chosen on the basis of hop tests
commonly described in the literature [16, 821], as well
as clinical experience, and were designed to reflect various
hop qualities. The tests should also be easy to administer
in a clinical setting. The subjects performed three to five
practice trials followed by three maximum approved trials
for the vertical jump, the hop for distance and the drop
jump, followed by a double hop for distance. However, if
the subjects increased their hop performance in all three
hops, additional hops were performed until no increase
was seen. The square hop and the side hop were tested
once. Three minutes of rest were used between each hop
test. The best trial for each leg in each test was used for
data analysis. The hop tests were videotaped for sub-
sequent control of test procedures.
Table 1 Descriptive characteristics of healthy subjects and patients
Age (years) Height
(cm)
Weight
(kg)
Tegner
before
injury
PAS
before
injury
Tegner at
test occasion
PAS at test
occasion
Weeks
injury/op-test
Healthy subjects
Male (n=9) 29±5 181±6 84±10
Female (n=6) 26±4 168±8 61±6
All subjects (n=15) 28±4 175±9 75±14
ACL injury
Male (n=18) 28±7 181±8 91±17 7.5 (2.0) 4.0 (1.0) 4.0 (2.2) 2.5 (1.0) 50±48
Female (n=12) 36±8 167±5 71±12 4.5 (3.5) 3.0 (1.0) 3.0 (1.0) 3.0 (1.0) 45±35
All subjects (n=30) 31±9 175±9 83±18 7.0 (3.0) 3.0 (1.0) 4.0 (1.2) 3.0 (1.0) 48±43
ACL reconstruction
Male (n=25) 27±8 180±8 81±11 8.0 (2.0) 3.0 (1.0) 4.0 (3.5) 3.0 (1.5) 28±2
Female (n=10) 27±7 167±5 60±5 7.0 (2.5) 3.5 (1.0) 3.0 (1.0) 3.0 (1.0) 28±2
All subjects (n=35) 27±7 177±10 75±13 8.0 (2.0) 3.0 (1.0) 4.0 (2.0) 3.0 (1.0) 28±2
All values are expressed as means (±SD), except for Tegner activity score and Physical Activity Scale (PAS), which is expressed as median
values (interquartile range)
780
Hop tests
Vertical jump (Fig. 1a)
The vertical jump test was performed as a counter-
movement jump. The starting position was an upright
position with the hands place d behind the back. The
subjects quickly bent their knee as much as desired and
then immediately jumped upwards, attempting to max-
imise the height jumped. A computerised system (Mus-
cleLab, Ergotest Technology) using a field of infrared
light (approximately 10 mm above the floor), serving as
a ‘‘contact mat’’, made it possible to measure the flight
time. The system then converted the flight time into
jump height in centimetres.
Hop for distance (Fig. 1b)
The subjects stood on the test leg and then hopped as far
as possible and landed on the same leg. Free leg swing
was allowed. The hands were placed behind the back.
The subjects were instructed to perform a controlled,
balanced landing and to keep the landing foot in place
(i.e. no extra hops were allowed) until (2–3 s) the test
leader had registered the landing position. Failure to do
so resulted in a disqualified hop. The distance was
measured in centimetres from the toe at the push-off to
the heel where the subject landed.
Drop jump followed by a double hop for distance
(Fig. 1c)
The starting position was standing on the leg to be tested
on a box, at a height of 30 cm, with the hands behind the
back. Forty-fi ve centimetres in front of the box, a strip of
tape marked the starting line. The subjects jumped down
on one leg, without crossing or touching the starting line,
and then immediately performed two one-legged maxi-
mum hops forward. Th e subjects were instructed to
Fig. 1 Five single leg hop tests
were used: a vertical jump,
b hop for distance, c drop jump
followed by a double hop for
distance, d square hop and
e side hop
781
perform a controlled, balanced landing and to keep the
landing foot in place (i.e. no extra hops were allowed)
until (2–3 s) the test leader had regi stered the landing
position. Failure to do so resul ted in a disqualified hop.
The distance was measured in centimetres from the
starting line to the heel where the subject landed.
Square hop (Fig. 1d)
The subj ects stood on the leg to be tested, with their
hands behind their back, outside a 40·40 cm square
marked with tape on the floor. A 10 cm frame was also
marked around the square with tape. For the right leg,
the subjects were instructed to jump clockwise in and out
of the square as many times as possible during a period of
30 s. The numb er of successful jumps performed, with-
out touching the taped frame, was recorded. Touching
the taped frame was recorded as an error and, if more
than 25% of the jumps had errors, a second trial of 30 s
was performed after a 3-min rest period. For the left leg,
the subject performed the test in a counter-cl ockwise
mode. This test was modified from O
¨
stenberg et al. [21].
Side hop (Fig. 1e)
For the side hop test, the subjects stood on the test leg,
with their hands behind their back, and jumped from side
to side betw een two parallel strips of tape, placed 40 cm
apart on the floor. The subjects were instructed to jump
as many times as possible during a period of 30 s. The
number of successful jumps performed, without touching
the tape, was recorded. Touching the tape was recorded
as an error and, if more than 25% of the jump s had
errors, a second trial of 30 s was performed after a 3-min
rest period. This test was modified from Itoh et al. [4].
Statistical analysis
Test–retest analysis was determined by an intraclass
correlation coefficient (ICC) with a 95% confidence
interval (CI) [27]. The methodological error in percent
was calculated according to the formula [28]:
[e/m] 100 = % difference between test
e the square root of [
P
(d
2
)/2n]
d difference between tests
n number of subjects
m mean value.
The mean and standard deviation were calculated for
the jump tests.
Wilcoxon’s signed rank test was used for dependent
values and the Mann–Whitney U test was used for
independent values. The Spearman Rank was used to
study the relationship between dependent variables. The
level of significance was set at P £ 0.05.
The lower limb symmetry index (LSI) was calculated
to determine whether a side-to-side leg difference was
classified as normal or abnormal. The LSI is defined as
the ratio of the involved limb score and the uninvolved
limb score expressed in per cent (involved/unin-
volved · 100 = LSI). In this study, an LSI greater than
or equal to 90% [10, 20] was classified as normal.
Sensitivity, specificity and accuracy were calculated
for the five hop tests and for the test battery using the
following definitions.
Sensitivity (= number of patients classified as
abnormal/total number of patients) expresses the per-
centage probability that the tests would demonstrate an
abnormal LSI in the patients [29].
Specificity (= number of healthy subjects classified as
normal/total number of healthy subjects) expresses the
percentage probability that the tests would demonstrate
a normal LSI in the normal subjects [29].
Accuracy (= number of patients classified as
abnormal + number of healthy subjects classified as
normal/total number of patients and healthy subjects) is
defined as the percentage probability that the tests
would demonstrate a normal LSI in the normal subjects
and an abnormal LSI in the patients [29].
A factor analysis with a principal axis factoring,
varimax rotation, and for two factors was applied for
evaluation of the structure of the test battery.
Results
Test–retest reliability for the five hop tests
Significant differences were found between test occasion
1 and 2 for male subjects and for male and female
subjects combined in the hop for dista nce (P=0.02) and
the square hop (P=0.001). A significant difference was
also found between test occasion 1 and 2 for all subjects
in the side hop (P=0 .01). No significant differences were
found between test occasion 2 and 3 in any of the five
hop tests, as shown in Table 2.
The ICC, 95% CI and methodological error in per-
cent and in absolute values are presented in Table 2.In
the five tests, the ICC between test occasion 2 and 3
ranged from 0.85 to 0.97 and the methodological error
ranged from 3 to 6%.
Comparison of hop performance between healthy male
and female subjects
A comparison between healthy male and female sub-
jects’ hop performance in the five hop tests on test
782
occasion 3 is presented in Table 3. Significant differ-
ences were found between males and female s in the
vertical jump (P=0.03), the hop for distance (P=0.03)
and the drop jump followed by a double hop for
distance (P=0.01) but not in the square hop and the
side hop. No significant difference was, however, found
in any of the tests when comparing the absolute values
for side-to-side difference in males and females. Fur-
ther analyses were therefore conducted, regardless of
gender.
Hop pe rformance in patients
A significant difference between the injured and unin-
jured side was found in all the hop tests except for the
square hop tests in patients with an ACL injury and in
all the tests in patients who had undergone ACL
reconstruction (Table 4).
Comparison of hop performance between healthy
subjects and patients
Patients with an ACL injury and patients who had
undergone ACL reconstruction had a significantly larger
side-to-side difference in all the tests except for the
square hop compared with healthy subjects (Table 5).
The results of the square hop test did not reveal a sig-
nificant diff erence between healthy subjects and patients
when comparing the side-to-side difference.
A normal LSI for the five hop tests ranged from 67 to
100% in the healthy subjects, from 23 to 57% in the
patients with an ACL injury and from 14 to 49% in the
Table 2 Test–retest reliability between test occasion 1 and 2 (Test
1–2
) and test occasion 2 and 3 (Test
2–3
)
Test P-value ICC 95% CI Methodological error
% cm or jumps
Vertical jump (cm)
Male (n=9) Test
1–2
0.08 0.83 0.61–0.93 8 1.4
Test
2–3
0.85 0.95 0.88–0.98 4 0.7
Female (n=6) Test
1–2
0.72 0.95 0.84–0.99 5 0.7
Test
2–3
0.82 0.97 0.90–0.99 4 0.6
All subjects (n=15) Test
1–2
0.11 0.89 0.79–0.95 7 1.2
Test
1–2
0.94 0.97 0.93–0.98 4 0.6
Hop for distance (cm)
Male (n=9) Test
1–2
0.02 0.91 0.78–0.97 3 4.2
Test
2–3
0.20 0.86 0.67–0.95 3 4.6
Female (n=6) Test
1–2
0.35 0.88 0.64–0.96 3 4.7
Test
2–3
0.08 0.98 0.93–0.99 2 2.1
All subjects (n=15) Test
1–2
0.02 0.94 0.88–0.97 3 4.3
Test
2–3
0.07 0.95 0.90–0.98 3 3.7
Drop jump followed by a double hop for distance (cm)
Male (n=9) Test
1–2
0.07 0.80 0.54–0.92 3 9.6
Test
2–3
0.41 0.85 0.65–0.94 3 9.6
Female (n=6) Test
1–2
0.43 0.67 0.19–0.89 6 15.0
Test
2–3
0.13 0.91 0.73–0.97 3 8.3
All subjects (n=15) Test
1–2
0.07 0.85 0.72–0–93 4 12.1
Test
2–3
0.13 0.93 0.85–0.96 3 8.7
Square hop (jumps)
Male (n=9) Test
1–2
0.00 0.64 0.18–0.87 13 6.9
Test
2–3
0.09 0.78 0.50–0.91 5 3.1
Female (n=6) Test
1–2
0.06 0.55 0.01–0.85 12 6.9
Test
2–3
0.48 0.89 0.67–0.97 5 3.2
All subjects (n=15) Test
1–2
0.00 0.58 0.25–0.78 13 6.9
Test
2–3
0.08 0.85 0.71–0.93 5 3.1
Side hop (jumps)
Male (n=9) Test
1–2
0.06 0.72 0.39–0.88 9 4.5
Test
2–3
0.61 0.78 0.51–0.91 5 3.0
Female (n=6) Test
1–2
0.10 0.87 0.62–0.96 14 5.5
Test
2–3
0.58 0.95 0.83–0.98 8 3.5
All subjects (n=15) Test
1–2
0.01 0.87 0.75.0.94 10 4.8
Test
2–3
0.95 0.93 0.87–0.97 6 3.2
P-values, intraclass correlation coefficients (ICC), 95% confidence intervals (CI) and the methodological errors are given in percent and in
absolute values
783
patients who had undergone ACL reconstruction
(Fig. 2).
Sensitivity, specificity and accuracy of the five hop tests
Table 6 shows the sensitivity, specificity and accuracy of
the five hop tests. Sensitivity ranged from 43 to 77% in
the patients with an ACL injury. Sensitivity in the pa-
tients who had undergone ACL reconstruction ranged
from 51 to 86%. Specificity ranged from 67 to 100% in
the five hop tests. Accuracy ranged from 58 to 80% in
the patients with an ACL injury. Accuracy in the pa-
tients who had undergone ACL reconstruction ranged
from 56 to 86%.
Correlation between the five hop tests
The correlation in healthy subjects and patients ranged
from r
s
=0.70 to r
s
=0.94 (P=0.01) between the three
maximum hop tests (vertical jump, hop for distance and
drop jump followed by a double hop for distance). The
correlation in healthy subjects and patients ranged from
r
s
=0.72 to r
s
=0.92 (P=0.01) between the two endur-
ance hop tests (square hop and side hop). The correla-
tion between the three maximum hop tests and the two
endurance hop tests ranged from r
s
=0.29 to r
s
=0.57
(P=0.05) in the healthy subjects and from r
s
=0.62 to
r
s
=0.88 (P=0.01) in the pa tients.
Factor analysis on the five hop tests
The factor analysis on the healthy subjects as wells as the
factor analysis on the patients divided the five hop tests
in factor one: maximal hop tests (vertical jump, hop for
distance and drop jump followed by a double hop for
distance) and facto r two: endurance hop tests (square
hop and side hop).
The test battery
The following three tests were chosen for the test bat-
tery: (1) the vertical jump, (2) the hop for distance and
(3) the side hop.
Among healthy subjects, 3 of 15 (20%) were classified
as abnormal in at least one of the three tests in the test
battery. Among patients with an ACL injury ,12of30
(40%) obtained abnormal LSI values in all three tests
and 4 of 30 (13%) obtained normal values in all three
tests. Twenty-six of 30 (87%) patients with an ACL in-
jury obtained abnormal LSI values in at least one of the
three tests. Among patients who had undergo ne ACL
reconstruction, 19 of 35 (54%) obtained abnormal LSI
values in all three tests and three of 35 (9%) obtained
normal values in all three tests. Thirty-two of 35 (91%)
patients who had undergone ACL reconstruction ob-
tained abnormal values in at least one of the three tests.
The sensitivity of the test battery, i.e. identifying a
patient as abnormal when at least one of the three tests
produced an abnormal LSI value, was 87% in the pa-
tients with an ACL injur y and 91% in the patients who
had undergone ACL reconstruction. The accu racy of the
test battery, i.e. identifying a healthy subject as normal
when all three tests produced a normal LSI value and
identifying a patient as abnormal when at least one of
the three tests produced an abnormal LSI value, was
found to be 84 and 88% respectively.
The square hop was not chosen due to its inability to
discriminate between the side-to-side difference in heal-
thy subjects and patients (Table 5). The square hop also
showed the lowest specificity (67%) and acc uracy (58
and 56%) of the five hop tests . The correlation with the
side hop ranged from r
s
=0.72 to r
s
=0.92 (P=0.01) for
Table 4 Means, standard
deviations (SD) in the five hop
tests in patients with ACL
injury and patients who have
undergone ACL reconstruction
(ACL recon.)
P-values between the injured
and the uninjured sides are
given
Test ACL injury (n=30) P-value ACL recon (n=35) P-value
Injured Uninjured Injured Uninjured
Vertical jump (cm) 11.5±5.4 14.5±5.4 0.05 13.3±5.0 17.5±4.6 <0.00
Hop for distance (cm) 115±39 135±29 <0.04 128±28 148±23 <0.00
Drop jump followed by
a double hop for distance (cm)
225±83 270±55 <0.03 253±56 297±48 <0.00
Square hop (jumps) 38±18 46±15 NS 49±17 57±12 <0.03
Side hop (jumps) 28±17 39±16 <0.01 39±16 49±13 <0.00
Table 3 Means, standard deviations (SD) in the five hop tests on
test occasion 3 for the right and left leg
Test All subjects
(n=15)
Male
(n=9)
Female
(n=6)
P-value
Vertical jump (cm) 16.7±3.7 18.1±3.3 15.0±3.7 <0.03
Hop for distance (cm) 151±16 160±11 137±13 <0.01
Drop jump followed
by a double hop
for distance (cm)
304±34 320±27 281±30 <0.01
Square hop (jumps) 62±7 62±6 60±9 NS
Side hop (jumps) 50±13 55±6 41±16 NS
P-values between males and females among healthy subjects are
given (NS=not significant)
784
all subjects, indicating a strong relationship between the
two endurance hop tests.
The drop jump followed by a double hop for distance
was not chosen due to its high correlation with the sin-
gle-leg hop for distance (r
s
>0,80, P=0.01), accuracy
similar to that of the hop for distance in the patients
with an ACL injury (62 vs. 69%) and identical to that
for the patients who had undergone ACL reconstruction
(74%). We therefore concluded that the drop jump fol-
lowed by a double hop for distance and the hop for
distance were equal and measured the same ability.
Discussion
The principal finding in this study was that a test bat-
tery, consisting of the vertical jump, the hop for distance
and the side hop tests, had a high ability to discriminate
between the hop perfo rmance of the injured and the
uninjured side both in patients 11 months after an ACL
injury and in patients 6 months after ACL reconstruc-
tion. The test battery may help in the process of deciding
whether and when patients can safely return to strenu-
Table 6 Results for sensitivity, specificity and accuracy in the five hop tests for healthy subjects (n=15), patients with ACL injury (n=30)
and patients who have undergone ACL reconstruction (n=35)
Vertical jump Hop for distance Drop jump followed by
a double hop for distance
Square hop Side hop
Sensitivity (%)
ACL injury 67 53 43 53 77
ACL recon. 86 63 63 51 69
Specificity (%)
Healthy subjects 87 100 100 67 87
Accuracy (%)
ACL injury 73 69 62 58 80
ACL recon. 86 74 74 56 74
P-values for comparisons between healthy subjects and patients with ACL injury and ACL reconstruction (ACL recon.) are given
Table 5 Means, standard deviations (SD) for side-to-side difference in the five hop tests
Test Healthy subjects (n=15) ACL injury (n=30) P-value ACL recon. (n=35) P-value
Vertical jump (cm) 1.2±1.4 3.0±2.5 <0.01 4.3±2.8 <0.01
Hop for distance (cm) 6±4 21±24 <0.05 20±11 <0.01
Drop jump followed by a
double hop for distance (cm)
8±7 45±62 <0.01 44±32 <0.01
Square hop (jumps) 4±3 7±12 NS 8±9 NS
Side hop (jumps) 4±3 11±9 <0.05 10±9 <0.05
47%
57%
47%
23%
37% 37%
49%
67%
87%
100%100%
87%
33%
34%
14%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Vertical jump Hop for distance
Drop jump followed
by a double hop for
distance
Square hop Side hop
Healthy
ACL injury
ACL recon.
Fig. 2 The percentage of
healthy subjects (n=15) and
patients with ACL injury
(n=30) and ACL reconstruc-
tion (ACL recon.)(n=35) clas-
sified as normal in the five hop
tests
785
ous physical activities after an ACL injury or recon-
struction. The test battery has, however, to be studied in
prospective randomised trails to be able to draw definite
conclusions on its actual ability to contribute to the
decision making process.
Single-leg hop tests are commonly used to study knee
function in patients with an ACL injury and are de-
signed to reflect the demands of a high level of physical
activity [16, 821]. In the literature it is argued that by
using a variety of hop tests, different hop qualities can be
evaluated and thereby increase the opportunity to detect
discrepancies in hop performance (i.e. increase the test
sensitivity) [1, 4, 5, 16]. The importance of hop perfor-
mance testing of patients after ACL reconstruction in a
fatigued state has also been advocated [8]. In the present
study three different maximum hop tests and two
endurance hop tests were used.
The difference between the three maximum hop tests
and the two endurance hop tests is reflected by the
correlation between the two types of hop tests, indicat-
ing a fair to moderate [30] degree of relationship
(r
s
=0.29–0.57) in the healthy subjects. O
¨
stenberg et al.
[21] reported similar correlations between the square
hop and the vertical jump (r=0.12) and the single-leg
hop for distance (r=0.38). The results indicate that the
two types of hop tests measure different aspects of
jumping ability, which is further confirmed by the factor
analysis on the five hop tests. Patients with an ACL
injury had, however, a strong relationship (r
s
=0.82–
0.88) between the two types of hop tests. One explana-
tion could be that the patients with ACL injury in this
study are not as homogeneous a group as the patients
who had undergone ACL reconstruction, especially in
terms of the interval between the index injury and the
test occasion and in the diversity of the functional defi-
cits.
During the two endurance hop tests, square hop and
side hop, the patients perfo rmed as many jumps as
possible during a period of 30 s, thereby demanding
knee stability while developing muscle fatigue. The side
hop test used by Itoh et al. [4] was modified not only by
increasing the test duration from less than 2 to 30 s but
also by increasing the distance the patients were required
to jump from 30 to 40 cm. This could explain the higher
sensitivity of 77% for the side-hop test found in the
present study compared with the 44% in the study by
Itoh et al. [4]. The reported sensitivity in these studies
should, however, be compared with caution, due to
different populations in terms of the time between the
injury and the test occasion, for example. In this study, a
sensitivity of 53% at a 90% LSI cut-off score in the
single-leg hop for distance in the patients with an ACL
injury was noted, which is in accordance with Noyes
et al. [5] and Itoh et al. [4], who observed a sensitivity of
52 and 42%, respectively, at an 85% LSI cut-off score.
In a study by Barber et al. [1], many of the healthy
subjects scored outside the normal lower limb symmetry
range in the vertical jump and specificity was as low as
48% at 90% LSI). This is considerably different from
the specificity of 87% in the present study, which is a
more acceptable result. One explanation for this differ-
ence in results could be due to the fact that Barber et al.
[1] used the jump-and-reach method, which has in an-
other previous study showed poor reliability [coefficient
of variation (CV) of 9.9%] [20].
The ICC values ranged from 0.85 to 0.97 for the five
different hop tests, indicating that all the tests had high
reliability. The importance of familiarisation needs to be
mentioned, as a significant increase in performance was
seen between test occasion 1 and 2 in the hop for dis-
tance and in the square hop. The difference may be the
result of a learning process. The patients therefore
practiced and were thoroughly familiarised at the
physical therapy clinic before the test occasions.
The test–retest result in the vertical jump (ICC 0.97)
is in agreement with those reported by Wilson et al. [31]
and Manske et al. [32], who obtained ICC values of 0.97
and 0.98 using other apparatus. Several authors have
described and tested the reliability of the single-leg hop
for distance in healthy subjects [ 7, 14, 32] and patients
after an ACL injury [10, 14]. ICC values ranging from
0.89 and 0.97 are reported [14, 32]. These results agree
with the ICC value of 0.95 in this study.
The square hop and the side hop were generally
performed only once by the healthy subjects. Despite
this fact, the tests showed high reliability for both the
square hop (ICC 0.85) and the side hop (ICC 0.93).
Three of the patients, who had errors in more than 25%
of the jumps, in one of the two tests, made a second
attempt. To minimise the effect of fatigue, 3 min of rest
were given before the second attempt. The number of
trials was limited in order to control the fatigue effects
that were induced and to reduce the total time of the test
battery.
The results of the present study revealed no differ-
ence between males and females in the side-to-side
comparison in any of the tests. Patients can therefore
be evaluated on an individual basis, regardless of
gender. This is also in accordance with previous studies
[1, 4, 20].
An LSI of both 85 and 90% has been advocated to
assess whether a hop test is normal or abnormal [1, 3, 8,
10, 20, 21 ]. Fitzgerald et al. [3] described a decision-
making scheme for returning patients with an ACL in-
jury to a high level of physical activity. Patients suc-
cessfully returning to pre-injury levels of activity had a
mean hop test score of 95%, compared with the mean of
85% in the patients who failed rehabilitation. On the
basis of this, an LSI of 90% was chosen as the cut-off
score in this study.
786
The square hop test used by O
¨
stenberg et al. [21] was
modified in the present study. In order to force the pa-
tients to perform more demanding jumps, the volume of
the square was increased. Although good reliability
(ICC 0.85) was obtained in the square hop test, this test
was not able to discriminate healthy subjects from pa-
tients. It was therefore concl uded that the test was not
optimal when it came to evaluating patients with an
ACL injury or patients who had undergone ACL
reconstruction. A new test, the drop jump followed by a
double hop for distance, was designed for additional
demands. This test is characterised by high intensity with
regard to deceleration and acceleration forces. Even
though the intention was to design a new, more
demanding hop test, this was not supported by the re-
sults. The drop jump followed by a double hop for
distance showed a strong correlation with the more
established hop for distance test. The sensitivity and
accuracy were not in favour of the newly designed test.
To summarise, a test battery consisting of the vertical
jump, the hop for distance and the side hop produced
the most information. It could also be regarded as
advantageous in the clinical setting to use a test battery
comprising three tests, instead of four or five tests.
It is worrying to note that only one out of ten patients
were classified as normal (i.e. having >90% hop
performance on the injured side com pared with the
uninjured side) 11 months after an ACL injury and
6 months after ACL reconstruction, as it is now
customary to allow a return to full sports activities
6 months after ACL reconstruction [33, 34], with some
authors advocating a return to sports as early as
4 months post-operatively [35, 36].
Conclusion
The test battery consisting of both maximum single hop
performances: the vertical jump and the hop for distance
and hop performance while developing fatigue: the side
hop, produced high test–retest reliabili ty, sensitivity and
accuracy. Further, the test battery produced higher
values compared with any of the three hop tests indi-
vidually, revealing that only one out of ten patients had
restored hop performance 11 months after an ACL in-
jury and 6 months after ACL reconstruction. It is con-
cluded that this test battery showed a high ability to
discriminate between the hop performance of the injured
and the uninjured side both in pa tients with an ACL
injury an d in patients who have undergone ACL
reconstruction.
Acknowledgments This study was supported by grants from the
Swedish Centre for Research in Sports and Research and The
Local Research and Development Council for Gothenburg and
Southern Bohusla
¨
n Sweden.
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... One particular accurate and sensitive test, which consisted of three hop tests that could discriminate between injured and uninjured hop performance for patients who had undergone anterior cruciate ligament reconstruction, concluded to combine the vertical hop, the single-leg hop for distance and the side hop, which together assist in determining the most beneficial form an injured and the uninjured leg, as stated by Gustavsson et al. 31 . This form of test advances the understanding of the knee's development, as muscle fatigue is induced through a high demand on dynamic knee stability, although the side hop test has been determined as the most beneficial form of distinguishing between an uninjured and injured lower extremity. ...
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Background: Investigating the relationship between functional capacity and psychological readiness is of paramount importance when planning sport resumption following knee surgery. The aim of this study was to prospectively assess clinical and functional outcomes in athletes 6 months after primary anterior cruciate ligament (ACL) reconstruction and to evaluate whether jumping ability is related to psychological readiness to return to sport following ACL surgery. Methods: Patients who underwent ACL reconstruction were prospectively enrolled and evaluated pre-operatively and 6 months after surgery. Assessment included Lysholm score, International Knee Documentation Committee (IKDC) Subjective Knee Form, Tegner activity level, and the ACL-Return to Sport after Injury (ACL-RSI) scale. Jumping ability was instrumentally assessed by an infrared optical acquisition system using a test battery including mono- and bipodalic vertical jump and a side hop test. Patients were dichotomized by ACL-RSI into two groups: group A (ACL-RSI > 60), and group B (ACL-RSI < 60). Results: Overall, 29 males and two females from the original study group of 37 patients (84%) were available for clinical evaluation. Mean age at surgery was 34.2 years (SD 11.3). Mean body mass index (BMI) was 25.4 (SD 3.7). Mean overall Lysholm, IKDC, and ACL-RSI scores increased from pre-operatively (p < 0.001). No differences in Tegner score were reported (p = 0.161). Similarly, improvement in most variables regarding jumping ability were observed at follow-up (p < 0.05). According to ACL-RSI, 20 subjects were allocated in group A (ACL-RSI > 60), while 11 were allocated in group B (ACL-RSI < 60). A statistically significant difference in favor of patients in group A was recorded for the post-operative Lysholm and Tegner score, as well as Side Hop test LSI level (p < 0.05), while a trend for IKDC was observed without statistical significance (p = 0.065). Conclusions: Patients with higher values of ACL-RSI scores showed better functional and clinical outcomes as well as improved performance 6 months after ACL reconstruction.
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Background The association of the reactive strength index (RSI) during single-leg vertical continuous jumps (SVCJs) with single-leg hop tests in athletes after anterior cruciate ligament reconstruction (ACLR) is unclear. Thus, this study aimed to confirm the measurement properties of the RSI during SVCJs in athletes with ACLR at the phase of determining the timing of their return to sport. Methods RSI during SVCJs and single-leg hop (single, triple, and crossover) tests were measured for post-ACLR and healthy athletes. The limb symmetry index (LSI) was calculated using the measurements of each parameter. For each test, patients were divided into two subgroups according to their LSI score (≥90%, satisfactory; <90%, unsatisfactory). Fisher’s exact test was used to examine the association of single-leg hop tests with RSI during the SVCJs. Results A total of 21 post-ACLR and 17 healthy athletes completed all the tests. RSI during SVCJs were significantly lower on the involved limb than on the uninvolved limb in post-ACLR athletes (P < 0.001). The LSI of RSI during SVCJs of post-ACLR athletes were significantly lower than that of the healthy athletes (P < 0.01). Among the post-ACLR athletes, <30% of those with LSIs >90% in the single-leg hop tests had an LSI >90% of the RSI during SVCJs. Conclusions RSI during SVCJs of post-ACLR athletes was significantly lower on the involved limb than on the uninvolved limb, and the asymmetry was more remarkable in the SVCJs than in the single-leg hop tests.
Article
Context Up to 90% of pediatric athletes return to sport (RTS) after anterior cruciate ligament reconstruction (ACL-R); however, <50% RTS at the same level and second ACL injury rates are up to 32%. Objectives (1) Determine which physical and patient-reported outcome measures guide clinical decision-making on RTS in pediatric athletes after ACL-R and (2) present a framework with insights from cognitive and neurophysiological domains to enhance rehabilitation outcomes. Data Sources PubMed, CINAHL, Embrase, and Cochrane library databases and gray literature. Study Selection Data on pediatric (<18 years) ACL-R patients, RTS, tests, and decision-making were reported in 1214 studies. Two authors independently reviewed titles and abstract, excluding 962 studies. Gray literature and cross-reference checking resulted in 7 extra studies for full-text screening of 259 studies. Final data extraction was from 63 eligible studies. Study Design Scoping review. Level of Evidence Level 4. Data Extraction Details on study population, aims, methodology, intervention, outcome measures, and important results were collected in a data chart. Results Studies included 4456 patients (mean age, 14 years). Quadriceps and hamstring strength (n = 25), knee ligament arthrometer (n = 24), and hop tests (n = 22) were the most-reported physical outcome measures guiding RTS in <30% of studies with cutoff scores of limb symmetry index (LSI) ≥85% or arthrometer difference <3 mm. There were 19 different patient-reported outcome measures, most often reporting the International Knee Documentation Committee (IKDC) (n = 24), Lysholm (n = 23), and Tegner (n = 15) scales. Only for the IKDC was a cutoff value of 85% reported. Conclusion RTS clearance in pediatric ACL-R patients is not based on clear criteria. If RTS tests were performed, outcomes did not influence time of RTS. Postoperative LSI thresholds likely overestimate knee function since biomechanics are impaired despite achieving RTS criteria. RTS should be considered a continuum, and biomechanical parameters and contextual rehab should be pursued with attention to the individual, task, and environment. There is a need for psychological monitoring of the ACL-R pediatric population.
Article
Objective To investigate the prognostic capacity of individual hop tests, hop test batteries and other unilateral functional performance tests following anterior cruciate ligament (ACL) injury. Design Systematic review with meta-analysis. Data sources Six databases searched up to June 2021. Eligibility criteria Studies reporting associations between unilateral lower-limb function (eg, hop tests) following ACL injury and future (≥3 months) knee-related outcomes. Results Of 42 included studies (13 150 participants), all assessed the single-forward hop test and 32 assessed a repeated-forward hop test (crossover hop, triple hop, 6m-timed hop), mostly within a year after ACL injury/reconstruction. Results of meta-analyses indicated that higher single-forward and repeated-forward hop limb symmetry were associated with higher odds of return-to-sport 1–3 years post-ACL reconstruction (OR 2.15; 95% CI 1.30 to 3.54; OR 2.11; 95% CI 1.23 to 3.60, respectively). Higher single-forward and repeated-forward hop limb symmetry was associated with better self-reported symptoms and function 1–37 years after ACL injury (OR 2.51; 95% CI 1.62 to 3.88; OR 4.28; 95% CI 1.65 to 11.08, respectively). Higher limb symmetry on a repeated-forward hop does not appear to be associated with higher odds of successful rehabilitation without ACL reconstruction (OR 1.51; 95% CI 0.94 to 2.44). Achieving ≥90% limb symmetry on the single-forward hop was associated with reduced odds of knee osteoarthritis 5–37 years after ACL injury (OR 0.46; 95% CI 0.23 to 0.94). Conclusion Very low certainty evidence suggests single-forward and repeated-forward hop tests are prognostic indicators for important knee-related outcomes in individuals after ACL injury and may help stratify individuals at risk of poor outcomes to target rehabilitation interventions. PROSPERO registration number CRD42018092197.
Chapter
This chapter describes rehabilitation after ACL reconstruction, taking into account the all press-fit fixation: standard, after revision, osteoporotic bone fixation, and healing response reinsertion. Biomechanical knowledge is fundamental in early postoperative and subsequent follow-up treatment. Individual features have to be calculated. Proven and scientific backgrounds are made accessible. Exercises to be implemented without extensive technology are illustrated with examples. Coupled with the experience in athletes and occasional athletes, test options and special technical items are presented and discussed for qualification to return to sport or competition. Rehabilitation begins with exercises of basic sports and part of the prevention program. Prevention is a key issue today from many points of view such as the national economy, individual quality of life, and the cost unit or insurance. This once again underlines the demand for “prevention first.”
Article
Objectives To 1) present passing rates for different clinician-friendly (CF) test batteries and 2) determine the relationship between passing CF test batteries and passing gold standard (GS) return-to-sport (RTS) muscle function testing, 1 year after ACL reconstruction. Study design Cross-sectional registry study, level of evidence: 3. Setting Primary care. Participants Data from 588 patients (52% women, mean age 29.3 ± 9.8 years) were extracted from the Project ACL registry. Main outcome measures The passing rates for the different test batteries. Results The passing rate for GS test battery was 28% (95% CI, 24–32%) and the passing rate for the CF test battery with the lowest passing rate was 27% (95% CI 24–31%). The two CF test batteries with the strongest relationships with passing GS test battery showed that 51% (95% CI 43–59%) and 49% (95% CI 44–55%) of the patients who passed the respective CF test battery also passed the GS test battery. Conclusion A CF test battery can be as demanding to pass as a GS test battery, 1 year after ACL reconstruction. However, passing a CF test battery only gives patients a chance similar to a “coin flip” of also passing a GS RTS test battery.
Article
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Context Athletes are often examined for return to sports using a functional-testing algorithm. No research has determined whether a closed kinetic chain (CKC) isokinetic testing bout influences the reliability of functional tests. Objective To determine whether a concentric CKC isokinetic test bout alters test–retest reliability of lower extremity functional testing. Design Subjects participated in velocity-spectrum CKC isokinetic bouts on 2 days 1 week apart. Setting Hospital-based clinic. Participants 28 normal subjects (mean age 26.7 years, height 27.2 cm, weight 75.8 kg). Analysis and Results Means and SDs were determined. Intraclass correlation coefficients were used to calculate test–retest reliability and between days 1 and 2 ranged from .91 to .98. Conclusions Even after a CKC isokinetic test bout, test–retest reliability of functional tests is very high. Future research should determine test–retest reliability of functional tests for patients with lower extremity pathology.
Article
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The purpose of this study was to evaluate the effectiveness of five hopping, jumping, and cutting-type (shuttle run) tests in determining lower extremity functional limitations in anterior cruciate ligament- (ACL) deficient knees. Ninety-three normal subjects were tested. No statistical significance was found between right and left lower limb scores (limb symmetry index) as related to sports activity level, gender, or dominant side. This allowed an overall symmetry index score to be established for the population as a whole. An 85% symmetry index score was found in more than 90% of the normal population for the one-legged hop for distance test and the one-legged timed hop test. Thirty-five patients with ACL-deficient knees were tested. The patients also had KT-1000 and Cybex testing and completed questionnaires rating symptoms, sports activity levels, and sports functional limitations. The cutting-type tests and the vertical jump test did not detect functional limitations in a reliable manner. In the one-legged hop tests, 50% of the patients performed normally, however, all reported giving-way episodes with sports, indicating a lack of sensitivity of these tests in defining functional limitations. Patients with abnormal one-legged hop test scores were considered at serious risk for giving way and limitations during sports activities. Statistically significant relationships were found among abnormal scores on the one-legged hop-type tests and (1) self-assessed difficulty with pivoting, cutting, and twisting, (2) quadriceps weakness (Cybex), and (3) patellofemoral compression pain.
Article
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This study assessed the sensitivity of four different types of one-legged hop tests. The goal was to deter mine alterations in lower limb function in ACL deficient knees. Regression analyses were conducted between limb symmetry as measured by the hop tests and muscle strength, symptoms, and self-assessed func tion. In 67 patients, 50% had abnormal limb symmetry scores on a single hop test. When the results of two hop tests were calculated, the percent of abnormal scores increased to 62%. The percentage of normal scores indicated that these hop tests had a low sensi tivity rate. However, the high specificity and low false- positive rates allow the tests to be used to confirm suspected defects in lower limb function. Statistical trends were noted between abnormal limb symmetry on the hop tests and low velocity quadriceps isokinetic test results.
Article
This investigation was designed to determine the test-retest reliability of a functional one legged hop test for distance in individuals with and without anterior cruciate ligament (ACL) reconstruction. Twenty subjects (X = 20.85 years) with no prior history of lower extremity injury, and 13 subjects (X = 22.40 years) with ACL reconstruction participated in this study. Testing occurred on two separate days with at least 24 h between testing sessions. The subjects executed a protocol consisting of a 5-min warm-up on a stationary bike, followed by three separate trial hops. This was followed by three separate hops which were measured and recorded. The distance travelled for each hop was measured using a standard measuring tape. The same protocol was then repeated on the contralateral limb. The leg tested first was randomized with each subject. The subjects were then asked to return on the second day, wearing the same pair of athletic shoes, and repeat the identical protocol. The mean of the three hops were used in data analysis. Paired t-tests revealed no significant difference between the dominant and non-dominant legs on either pre-test or post-test in subjects with healthy knees. A significant difference was found when comparing involved to uninvolved limb on both the pre-lest and post-test in patients with ACL reconstruction. There was no significant difference found from pre-test to post-test on either the dominant or non-dominant legs in healthy subjects or from the involved to uninvolved in patients with ACL reconstruction. Interclass correlation coefficients (ICC) revealed values of 0.92 and 0.96 for dominant and non-dominant legs, respectively. For individuals with ACL reconstruction, ICC values were 0.89 for both the involved and uninvolved limb. The results of this study suggest that the one legged hop test for distance is a reliable test for both young adults with healthy knees and those who have had ACL reconstruction. This test, along with others, may aid clinicians in determining whether patients are ready to return to prior level of activity.
Article
Study design: Case study of a basketball player who underwent an alternative surgical procedure for anterior (cruciate ligament (ACL) reconstruction and outline of the rehabilitation process designed for this procedure. Objectives: To describe the surgical procedure, detail the rehabilitation program, and report on this patient's clinical outcome. Background: Anterior cruciate ligament injury, its treatment, and rehabilitation continue to be an area of interest to both clinicians and researchers. Surgical procedures have been refined and rehabilitation programs are constantly being evaluated and updated to allow the safest and most predictable return to activity. Currently, the autogenous bone-patellar tendon-bone graft is the graft of choice for ACL reconstruction. Typically the graft is taken from the ipsilateral knee. An alternative procedure is to take the graft from the contralateral, noninvolved knee, allowing 2 separate rehabilitation programs to take place. Methods and measures: The patient was followed from the time of injury to 2 years postoperatively. Data collected included range of motion, isokinetic strength scores, ligament stability scores, subjective evaluation, and functional measures. Results: At 3 weeks postoperative the patient had nearly full range of motion in both knees, normal gait, and was beginning sport-specific drills. He was shooting the basketball and jumping by 5 weeks and returned to competitive sports 6 weeks after surgery. He was able to play in all 32 games of the season, starting in 23 of them. Conclusions: Using the contralateral patellar tendon graft may be appropriate for primary ACL reconstruction of patients, particularly those desiring an early expedient return to athletic competition.
Article
We identified 60 consecutive patients with combined anterior cruciate and medial collateral ligament (ACL- MCL) disruptions that were incurred during athletic endeavors. Each underwent acute reconstruction of the ACL. The arthroscopic data obtained at the time of reconstructive surgery was reviewed in order to deter mine the incidence of O'Donoghue's triad (the "unhappy triad"), consisting of ACL, MCL, and medial meniscus tears. Patients were subdivided into two groups for analysis based upon the degree of MCL injury at time of pres entation (Group I, 35 patients with a second-degree sprain; Group II, 25 patients with a complete, or third- degree injury). Medial meniscus tears were an uncom mon finding. Lateral meniscus tears significantly out numbered medial meniscus tears in both groups, oc curring in 25 (71 %) of Group I patients and 8 (32%) of those in Group II. Even chondral fractures of the lateral femoral condyle outnumbered medial meniscus tears [6 (17%) versus 4 (11 %)] in patients with a second- degree MCL sprain. Furthermore, when present in Group I patients, tears of the medial meniscus were associated with a concomitant lateral meniscus injury. Group II patients were more likely (60%) than Group I not to have any meniscal abnormality at all. We conclude that the classic O'Donoghue triad is, in fact, an unusual clinical entity among athletes with knee injuries; it might be more accurately described as a triad consisting of ACL, MCL, and lateral meniscus tears. This injury combination appears to be more common when an incomplete, or second-degree, tear of the medial collateral has occurred. Third-degree MCL injuries in conjunction with ACL disruptions seem to "protect" joint surfaces, as patients with these injuries most commonly demonstrate an absence of further intraarticular abnormality (meniscal or chondral).
Article
The purpose of this study was to register prospectively the injuries in female soccer and to study their correlation to potential risk factors. A total of 123 senior players from eight teams of different levels were followed during one season. Isokinetic knee muscle strength at 60 and 180°/s, one-leg-hop, vertical jump, square-hop, and continuous multistage fitness test (MFT) were tested at the end of the pre-season. In addition, Body Mass Index (BMI) and general joint laxity were measured. During the season, April–October, all injuries resulting in absence from one practice/game or more were registered. Forty-seven of the 123 players sustained altogether 65 injuries. The total injury rate was 14.3 per 1000 game hours and 3.7 per 1000 practice hours. The knee (26%) was the most commonly injured region followed by the foot (12%), ankle (11%), thigh (11%) and back (11%). The risk of sustaining moderate and major injuries increased in the later part of the game or practice. Significant risk factors for injuries were an increased general joint laxity (odds ratio (OR)=5.3, P<0.001), a high performance in the functional test square-hop (OR=4.3, P=0.002), and an age over 25 years (OR=3.7, P=0.01). The injury rate was not different compared to male soccer, but knee injuries were more common, which is in accordance with previous studies. None of the risk factors identified in this study is easily applicable for future intervention studies in the attempts to reduce the injury rate in female soccer.