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Medial hamstring muscle activation patterns are affected 1-6 years after ACL reconstruction using hamstring autograft

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Although changes in hamstring muscle morphology after anterior cruciate ligament reconstruction (ACLR) using a semitendinosus autograft hamstrings-gracilis (HG) of the ipsilateral limb are recognized, alterations in muscle activation patterns have not been extensively studied. The purpose of this controlled laboratory trial was therefore to monitor muscle activation levels of the medial (MH) and lateral (LH) hamstring muscles in athletes who had undergone ACLR using a HG autograft and to contrast these to activation levels demonstrated by healthy controls. Surface electromyography (EMG) was sampled from bilateral hamstring muscles of 18 athletes 1-6 years after ACLR and 18 matched controls (CTRL) during the performance of two dissimilar exercises, both involving eccentric knee flexor activity. Peak normalized muscle activation levels were identified for MH and LH of both limbs during the performance of the Nordic Hamstring (NH) exercise and TRX(®) hamstring curl (TRX) exercise. A statistically significant limb by exercise interaction was found for peak activation levels of LH, due to significant interlimb differences in activation during the performance of the TRX exercise compared to more symmetrical activation during the NH (p < 0.001). A three-way interaction was found for peak activation levels of MH, due to group differences in peak muscle activation between limbs and exercise type (p = 0.025). Whereas CTRL group participants consistently favoured one limb over the other during the performance of both exercises, ACLR participants demonstrated dissimilar peak MH activation patterns between limbs during the performance of the NH exercise compared to the TRX. In light of these results and considering the surgical procedure, patients who undergo ACLR using a HG autograft from the ipsilateral limb may benefit from post-operative rehabilitation that involves muscle activation and strengthening specifically targeting the MH component.
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ArticleTitle Medial hamstring muscle activation patterns are affected 1–6 years after ACL reconstruction using hamstring
autograft
Article Sub-Title
Article CopyRight Springer-Verlag Berlin Heidelberg
(This will be the copyright line in the final PDF)
Journal Name Knee Surgery, Sports Traumatology, Arthroscopy
Corresponding Author Family Name Briem
Particle
Given Name Kristín
Suffix
Division Department of Physical Therapy, School of Health Sciences
Organization University of Iceland
Address Saemundargata 2, Reykjavik, 101, Iceland
Email kbriem@hi.is
Author Family Name Birnir
Particle
Given Name Bjartmar
Suffix
Division Department of Physical Therapy, School of Health Sciences
Organization University of Iceland
Address Saemundargata 2, Reykjavik, 101, Iceland
Email
Author Family Name Guðnason
Particle
Given Name Garðar
Suffix
Division Department of Physical Therapy, School of Health Sciences
Organization University of Iceland
Address Saemundargata 2, Reykjavik, 101, Iceland
Email
Author Family Name Árnason
Particle
Given Name Stefán Magni
Suffix
Division Department of Physical Therapy, School of Health Sciences
Organization University of Iceland
Address Saemundargata 2, Reykjavik, 101, Iceland
Email
Author Family Name Guðmundsson
Particle
Given Name Tómas Emil
Suffix
Division Department of Physical Therapy, School of Health Sciences
Organization University of Iceland
Address Saemundargata 2, Reykjavik, 101, Iceland
Email
Schedule
Received 14 July 2013
Revised
Accepted 16 September 2013
Abstract Purpose:
Although changes in hamstring muscle morphology after anterior cruciate ligament reconstruction (ACLR)
using a semitendinosus autograft hamstrings-gracilis (HG) of the ipsilateral limb are recognized, alterations
in muscle activation patterns have not been extensively studied. The purpose of this controlled laboratory
trial was therefore to monitor muscle activation levels of the medial (MH) and lateral (LH) hamstring muscles
in athletes who had undergone ACLR using a HG and to contrast these to activation levels demonstrated by
healthy controls.
Methods:
Surface electromyography (EMG) was sampled from bilateral hamstring muscles of 18 athletes 1–6 years
after ACLR and 18 matched controls (CTRL) during the performance of two dissimilar exercises, both
involving eccentric knee flexor activity. Peak normalized muscle activation levels were identified for MH
and LH of both limbs during the performance of the Nordic Hamstring (NH) exercise and TRX® hamstring
curl (TRX) exercise.
Results:
A statistically significant limb by exercise interaction was found for peak activation levels of LH, due to
significant interlimb differences in activation during the performance of the TRX exercise compared to more
symmetrical activation during the NH (p < 0.001). A three-way interaction was found for peak activation
levels of MH, due to group differences in peak muscle activation between limbs and exercise type (p = 0.025).
Whereas CTRL group participants consistently favoured one limb over the other during the performance of
both exercises, ACLR participants demonstrated dissimilar peak MH activation patterns between limbs during
the performance of the NH exercise compared to the TRX.
Conclusions:
In the light of these results and considering the surgical procedure, patients that undergo ACLR using a HG
autograft from the ipsilateral limb may benefit from post-operative rehabilitation that involves muscle
activation and strengthening specifically targeting the MH component.
Keywords (separated by '-') ACL reconstruction - Autograft - EMG - Hamstring
Footnote Information
UNCORRECTED PROOF
KNEE
1
2Medial hamstring muscle activation patterns are affected
31–6 years after ACL reconstruction using hamstring autograft
4Kristı
´n Briem Bjartmar Birnir Garðar Guðnason
5Stefa
´n Magni A
´rnason To
´mas Emil Guðmundsson
6Received: 14 July 2013 / Accepted: 16 September 2013
7ÓSpringer-Verlag Berlin Heidelberg 2013
8Abstract
9Purpose Although changes in hamstring muscle mor-
10 phology after anterior cruciate ligament reconstruction
11 (ACLR) using a semitendinosus autograft hamstrings-
12 gracilis (HG) of the ipsilateral limb are recognized, alter-
13 ations in muscle activation patterns have not been exten-
14 sively studied. The purpose of this controlled laboratory
15 trial was therefore to monitor muscle activation levels of
16 the medial (MH) and lateral (LH) hamstring muscles in
17 athletes who had undergone ACLR using a HG and to
18 contrast these to activation levels demonstrated by healthy
19 controls.
20 Methods Surface electromyography (EMG) was sampled
21 from bilateral hamstring muscles of 18 athletes 1–6 years
22 after ACLR and 18 matched controls (CTRL) during the
23 performance of two dissimilar exercises, both involving
24 eccentric knee flexor activity. Peak normalized muscle
25 activation levels were identified for MH and LH of both
26 limbs during the performance of the Nordic Hamstring
27 (NH) exercise and TRX
Ò
hamstring curl (TRX) exercise.
28 Results A statistically significant limb by exercise inter-
29 action was found for peak activation levels of LH, due to
30 significant interlimb differences in activation during the
31 performance of the TRX exercise compared to more
32 symmetrical activation during the NH (p\0.001). A
33 three-way interaction was found for peak activation levels
34 of MH, due to group differences in peak muscle activation
35 between limbs and exercise type (p=0.025). Whereas
36 CTRL group participants consistently favoured one limb
37
over the other during the performance of both exercises,
38
ACLR participants demonstrated dissimilar peak MH
39
activation patterns between limbs during the performance
40
of the NH exercise compared to the TRX.
41
Conclusions In the light of these results and considering
42
the surgical procedure, patients that undergo ACLR using a
43
HG autograft from the ipsilateral limb may benefit from
44
post-operative rehabilitation that involves muscle activa-
45
tion and strengthening specifically targeting the MH
46
component.
47
48
Keywords ACL reconstruction Autograft EMG
49
Hamstring
50
Introduction
51
Anterior cruciate ligament (ACL) injuries seriously impact
52
the lives of those who suffer them, and both direct and
53
indirect costs of ACL reconstruction (ACLR) and reha-
54
bilitation are immense [12,15,24]. Although not always
55
required [9,13], many of those who rupture their ACL
56
undergo surgery that aims to restore knee joint stability and
57
function by reconstructing the ligament, most commonly
58
with an autograft from the ipsilateral limb. This may be
59
necessary for individuals who participate in demanding
60
activities that involve pivoting and rapid acceleration/
61
deceleration. The most common harvest sites are the
62
patellar tendon [bone-patellar tendon-bone (BPTB)] and
63
semitendinosus muscle component of the hamstrings,
64
where strands from the gracilis muscle are frequently used
65
to augment the graft [hamstrings-gracilis (HG)].
66
Overall, risk of post-surgical complications, such as
67
anterior knee pain and range of motion (ROM) impair-
68
ments, seems to be greater when BPTB grafts are used,
A1 K. Briem (&)B. Birnir G. Guðnason
A2 S. M. A
´rnason T. E. Guðmundsson
A3 Department of Physical Therapy, School of Health Sciences,
A4 University of Iceland, Saemundargata 2, 101 Reykjavik, Iceland
A5 e-mail: kbriem@hi.is
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Knee Surg Sports Traumatol Arthrosc
DOI 10.1007/s00167-013-2696-4
Author Proof
UNCORRECTED PROOF
69 while relative knee joint laxity remains a concern for HG
70 reconstruction [18,19]. While joint stability may be ade-
71 quately restored, arthrokinematics of the joint and kine-
72 matics of the lower limb are affected and may influence the
73 rate of progression of knee OA [8,9,16,25]. Graft failure
74 rate is reportedly almost 6 % at a minimum 5 years post-
75 ACLR [32] and around 10 % 15 years after reconstruction
76 [5], with no demonstrable statistically significant difference
77 between graft types. Revision surgery has been shown to
78 result in worse patient-reported outcomes compared with
79 primary ACLR, and revisions have a threefold to fourfold
80 greater failure rate than prospective series of primary ACL
81 reconstructions [31].
82 Post-surgical muscle weakness is recognized to be
83 dependent on the graft donor site as is the need for specific
84 rehabilitation based on the graft used [33]. Quadriceps
85 strength and overall lower extremity function is rigorously
86 tested during the course of rehabilitation, particularly with
87 respect to whether an athlete is ready to return to high level
88 sports activities and competition [30]. Muscle strength of
89 knee flexors collectively is typically well monitored during
90 the months of rehabilitation after ACLR using an ipsilateral
91 HG autograft [30]. However, specific training and testing
92 for the medial versus lateral components is not routine,
93 despite findings demonstrating selective medial hamstring
94 (MH) weakness, even more than 2 years after surgery [3,
95 26]. This may be of particular importance in the light of the
96 mechanism of non-contact ACL injuries, as the MH com-
97 ponent has the potential to counter the external outward
98 rotating knee moments associated with ACL rupture [4].
99 Magnetic resonance imaging (MRI) has in recent years
100 been used to demonstrate the potentially negative effects of
101 HG harvesting for ACLR by evaluating quality of tendon
102 regeneration in the months and years after surgery, as well
103 as muscle cross-sectional area (CSA) or volume [6,20,21,
104 27]. A proximal migration of the muscle–tendon junction
105 of the semitendinosus is generally found [6,27], and this,
106 paired with muscle atrophy, may explain muscle weakness
107 that is most often found in tests performed in deep knee
108 flexion [2,6,29]. Ristanis et al. [23] used electromyogra-
109 phy (EMG) to investigate how ACLR using HG grafts
110 affected timing of muscle activation of the semitendinosus
111 and biceps femoris. They demonstrated significant elec-
112 tromechanical delay in the ipsilateral knee flexors com-
113 pared to the contralateral limb and controls. However, the
114 effect of the surgery on the magnitude of hamstring muscle
115 activation levels during functional exercises is an under-
116 investigated area. Identifying specific alterations may have
117 important implications with respect to rehabilitation after
118 ACLR and may thereby positively affect athletes’ suc-
119 cessful return to competition with minimal risk of re-injury.
120 Therefore, the main purpose of this controlled laboratory
121 trial was to assess muscle activation levels in bilateral
122
lower extremities during two dissimilar hamstring exer-
123
cises. Specifically, the aim was to contrast muscle activa-
124
tion patterns of MH versus lateral hamstring (LH) of
125
healthy athletes and individuals that had undergone ACLR
126
using a semitendinosus autograft. The ‘a priori’ hypothesis
127
was that interlimb differences in peak hamstring activation
128
would only be found in the reconstructed participants.
129
Materials and methods
130
Eighteen soccer players (ACLR group), who all had
131
undergone ACLR 1–6 years previously, were recruited
132
from the men’s and women’s top leagues in Iceland. Of
133
these 18 individuals, 12 were operated on the left side and
134
6 on the right. The 18 controls (CTRL group) were
135
recruited from the same teams and were matched for
136
gender, ‘involved’ side designation, height and weight
137
(Table 1). All ACLR participants had successfully returned
138
to full participation in their sport. Exclusion criteria were
139
any orthopaedic condition precluding them from full par-
140
ticipation in competition and history of muscle strain in the
141
knee flexor muscles within the past 3 months. The study
142
was approved by the National Bioethics Committee, and
143
informed consent was obtained from participants prior to
144
data collection.
145
Wireless surface EMG (Kine Pro, Hafnarfjordur, Ice-
146
land) was used to monitor muscle activity during two
147
exercises targeting eccentric activity of the hamstring
148
muscles, using a signal bandwidth of 16–500 Hz, sampling
149
at a rate of 1600 Hz. Electrodes were placed over the
150
muscle bellies of semitendinosus and biceps femoris
151
muscles (MH and LH) of both lower extremities. SENIAM
152
guidelines [28] were used for electrode placement as well
153
as palpation during muscle contraction in order to identify
154
the optimal position. The skin was cleaned and hair
155
removed if necessary prior to surface electrode placement.
156
The raw EMG data were high-pass filtered at 25 Hz, full-
157
wave rectified and the root-mean-square of the signal was
Table 1 Number of male versus female participants, leg dominance
as involved (‘Inv’) versus uninvolved (‘Un’) limb, and group mean
(SD) height, weight and body mass index (BMI)
ACLR CTRL
Male/female 8/10 8/10
Left/right dominance 2/16 5/13
‘Inv’/‘Un’ is the dominant leg 8/10 9/9
Age 23.7 (3.6) 20.5 (3.7)
Height (metres) 1.73 (0.09) 1.73 (0.08)
Weight (kg) 69.2 (11.8) 68.6 (11.2)
BMI 23.0 (2.4) 22.7 (2.0)
No significant group difference was found for any variable (n.s.)
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158 derived using a moving 250 ms window. Peak values,
159 identified during three trials of each exercise, were aver-
160 aged and normalized to the maximum signal collected
161 during three maximal voluntary isometric contractions
162 (MVIC), each lasting 5 s. MVIC measures for hamstring
163 muscles were made with the participants in prone, knees
164 flexed to 30°and the foot in a neutral position, using a belt
165 secured over the calcaneus to provide resistance.
166 Participants warmed up for 5 min on a stationary bike
167 before performing the MVIC task, after which they were
168 shown a short video clip of the exercises and subsequently
169 practiced them. During data collection, order of exercise
170 performance was randomized, and standardized instruc-
171 tions given during each of the three trials were recorded for
172 each exercise. The two exercises performed were the
173 Nordic hamstring exercise (NH) and TRX
Ò
hamstring curls
174 (TRX). Both involve simultaneous bilateral hamstring
175 performance and utilize the individual’s body weight and
176 gravity for resistance. However, while the feet and tibiae
177 are constrained for the NH exercise, the lower extremities
178 are relatively free during the TRX performance. The NH
179 exercise was performed by each participant lowering their
180 trunk as slowly as possible, with arms at their side for as
181
long as possible (eccentric knee flexor activity from 95°
182
knee flexion while maintaining hips at close to 0°: Fig. 1).
183
Time during the execution of the NH exercise was recorded
184
for each participant. A metronome was used to standardize
185
the performance of four phases of the TRX exercise; 1. hip
186
extension (concentric) from flexed to neutral hip position;
187
2. knee extension (eccentric) from flexed to 0°; 3. knee
188
flexion (concentric) returning from 0°to flexed knee
189
position; 4. hip flexion (eccentric) from 0°to starting
190
position. Performance time was standardized to 2.5 s, and
191
data from phase 2 (between beats 1 and 2 of the metro-
192
nome) were used for analysis (eccentric hamstring activity;
193
Fig. 2). Variables of interest included peak (normalized)
194
activation levels of the MH and LH EMG signal during the
195
eccentric performance of each of the two exercises for both
196
limbs.
197
Statistical analysis
198
After processing the EMG data, they were analyzed using
199
IBM SPSS Statistics version 20. A mixed model analysis of
200
variance (ANOVA) was used to evaluate each muscle’s
Fig. 1 Performance of the Nordic hamstring exercise
Fig. 2 Performance of the TRX hamstring curl exercise
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201 activity; within-subjects factors included limb (involved/
202 uninvolved) and exercise (NH/TRX), between the ACLR
203 and CTRL groups. Post hoc t tests were used where indi-
204 cated, to clarify ANOVA results. The alpha level was set at
205 0.05.
206 Results
207 The groups were matched for gender, height and weight,
208 and no group differences were found for mean age or
209 instances where the players’ dominant (kicking) leg was
210 the ‘involved’ versus ‘uninvolved’ side (Table 1). The
211 mean ±SD time utilized to perform the NH exercise was
212 4.0 ±1.3 and 3.8 ±1.0 s for the ACLR and CTRL
213 groups, respectively (n.s.).
214 While a main effect of limb was found across groups,
215 limbs and exercises for both hamstring muscles
216 (p\0.001), a statistically significant limb by exercise
217 interaction was found for peak activation levels of LH, due
218 to significant interlimb differences during the performance
219 of the TRX exercise compared to more symmetrical acti-
220 vation during the NH (p\0.001; Fig. 3). Post hoc analy-
221 ses revealed significantly lower activation levels of the
222 ‘involved’ limb during the TRX compared to the NH
223 exercise (p\0.001), while the ‘uninvolved’ side con-
224 versely demonstrated slightly (not significant) greater
225 activation levels on average. While not statistically sig-
226 nificant for LH, a three-way interaction was found for the
227 peak activation levels of MH, due to group differences in
228 peak muscle activation between limbs and exercise type
229 (p=0.025). Whereas CTRL group participants consis-
230 tently favoured one limb over the other during the perfor-
231 mance of both exercises, ACLR participants demonstrated
232 dissimilar peak MH activation patterns between limbs
233
during the performance of the NH exercise compared to the
234
TRX (Fig. 4).
235
Discussion
236
The principal findings of the study included significant
237
differences between ACLR and CTRL groups in interlimb
238
activation levels of MH, the muscle from which the graft
239
was harvested, between exercises. Additionally, general
240
exercise-dependent differences in peak hamstring muscle
241
activation levels were identified. Contrary to the hypothesis
242
made, interlimb differences were found in both groups, as
243
participants generally favoured one limb over the other
244
during the exercise performance, albeit to different degrees
245
depending on the exercise, as demonstrated by the inter-
246
action of limb and exercise.
247
The main effect of limb is hard to explain as the
248
involved/uninvolved designation was based on the surgical
249
limb of the ACLR group and no interlimb difference was
250
expected in the CTRL group. As seen in Table 1, this
251
finding is not clearly linked to leg dominance, according to
252
the definition used (favoured kicking leg). The operated
253
knee was on the left side 2/3 of the time, and therefore, the
254
same ratio of right limbs was labelled ‘uninvolved’. Par-
255
ticipants may have had a tendency to favour the right leg,
256
regardless of kicking preference, during the exercises, in
257
particular during the performance of the TRX exercise. The
258
two-way interaction of limb and exercise likely reflects the
259
greater freedom of performance during the TRX exercise
260
compared to the NH exercise. During the NH, the tibiae
261
were constrained in a closed chain performance, and in-
262
terlimb peak activation was generally more symmetrical
263
compared to that found during the performance of the
264
TRX, where disparity was greater. When interpreting these
Fig. 3 Mean (SE) LH peak muscle activation levels during the NH
and TRX exercise performance. Asterisks statistically significant
difference
Fig. 4 Mean (SE) MH peak muscle activation levels during the NH
and TRX exercise performance. Asterisks statistically significant
difference
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UNCORRECTED PROOF
265 results, one must keep in mind that muscle activation levels
266 measured with EMG do not equate to muscle strength or
267 force output, not measured in this study. Nonetheless, the
268 differences seen in relative activation of bilateral ham-
269 strings between exercises are unequivocal. The results
270 indicate the importance of including unilateral strength-
271 ening of key muscles as part of a comprehensive training
272 program to ensure specificity, just as when obtaining spe-
273 cific strength measures. Additionally, biofeedback may be
274 used to promote symmetrical, muscle-specific activation
275 during the exercises involving bilateral lower extremity
276 performance. This may be particularly important after
277 injuries that have led to muscle atrophy and inhibition.
278 There is some indication, albeit inconsistent, that biceps or
279 semimembranosus may in some cases hypertrophy, in what
280 may be viewed as a compensatory effort to counter semi-
281 tendinosus atrophy after ACLR [11,20,27]. Moreover, a
282 positive association has been found between degree of
283 tendon regeneration of the semitendinosus and knee flexor
284 strength measures [6], reflecting the importance of the
285 muscle’s recovery.
286 The interaction involving group differences in interlimb
287 peak activation levels of the MH between exercises may
288 reflect alterations in firing patterns resulting from surgery.
289 Alterations in activation patterns of individuals that have
290 undergone ACLR have previously been shown with respect
291 to timing (onset) of both MH and LH activation [23].
292 Results of the present study indicate that levels of muscle
293 activation during the performance of functional activities
294 are also affected, which may have implications for knee
295 joint arthrokinematics and function, possibly impacting
296 risk of graft failure or rate of osteoarthritis. The results
297 demonstrate that during the bilateral performance of both
298 exercises, individuals were able to favour one limb over the
299 other and that ACLR participants did so to varied degrees
300 between exercises and, seemingly, not to the same extent
301 between MH versus LH components. Single-limb exercises
302 should therefore possibly target medial versus lateral
303 components specifically by manipulating tibial rotation [7]
304 and knee flexion angle [22].
305 A limitation that may affect the interpretation of differ-
306 ences in the activation levels is the lack of strength mea-
307 sures for the participants of the study. Generally, interlimb
308 differences in muscle strength of up to 10 % may be con-
309 sidered normal, and one of the milestones clinicians look for
310 when determining whether an athlete is ready to return to
311 full participation of their sport is limb symmetry of
312 90–100 % [1,30]. Notably, the mean peak activation levels
313 recorded during both exercises may be considered rather
314 low, and our data for NH performance are much lower than
315 mean values recently reported by Ditroilo et al. [10] for
316 Biceps Femoris. This may, in part, be explained by their
317 normalization methods (isokinetic (eccentric) EMG data vs.
318
isometric), but may also be attributed to differences in
319
visual and verbal directions given to participants, affecting
320
their motivation and effort. These were standardized in this
321
study and would not have affected the interactions seen.
322
Ditroilo et al. did not investigate interlimb differences in
323
EMG activation levels during the NH performance, but this
324
was done by Iga et al., who found no significant difference
325
in a recent but small study [17]. Their outcome measures
326
were integrated EMG values over three 30°ROM windows
327
during the exercise. These were normalized to peak values
328
recorded during the same exercise, which likely explains
329
lack of interlimb difference.
330
In efforts to decrease risk of graft failure, post-operative
331
rehabilitation increasingly focuses on resolving neuro-
332
muscular deficits that often persist after ACLR and stan-
333
dard rehabilitation [14]. The results of the present study
334
suggest that rehabilitation strategies targeting hamstring
335
muscle function should include exercises for unilateral as
336
well as bilateral lower extremity performance to ensure
337
adequate effort from the index limb. Moreover, hamstring
338
exercises may prove more effective if care is taken to
339
effectively activate both MH and LH components. Long-
340
term prospective studies, however, are needed to shed light
341
on any potential that specific rehabilitation strategies tar-
342
geting semitendinosus have to influence tendon and muscle
343
morphology, muscle strength and activation, lower limb
344
kinematics and function after ACLR.
345
Conclusion
346
In the light of the results of the study and considering the
347
surgical procedure, outcomes for individuals undergoing
348
ACLR using a HG autograft from the ipsilateral limb may
349
be improved by including specific training for the MH
350
component as part of a comprehensive rehabilitation pro-
351
gram. Clinicians may find the NH a better choice than TRX
352
hamstring curls for bilateral, eccentric, hamstring
353
strengthening during rehabilitation after ACLR, although
354
the results indicate that single-limb exercises are important
355
to ensure optimal muscle performance.
356
Acknowledgments The authors would like to acknowledge Dr.
357
Thorarinn Sveinsson, Professor at the School of Health Sciences,
358
University of Iceland for his assistance during EMG data processing.
359
References
360
1. Adams D, Logerstedt DS, Hunter-Giordano A, Axe MJ, Snyder-
361
Mackler L (2012) Current concepts for anterior cruciate ligament
362
reconstruction: a criterion-based rehabilitation progression.
363
J Orthop Sports Phys Ther 42(7):601–614
364
2. Ahlen M, Liden M, Bovaller A, Sernert N, Kartus J (2012)
365
Bilateral magnetic resonance imaging and functional assessment
AQ1
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... Although this procedure is admittedly hard to realize in the field, individual thresholds to terminate an exercise set (e.g., ROM to downward acceleration <30 • ) should be implemented rather than predefining a fixed exercise volume. To improve the acute or chronic performance and quality of NHE execution by elevated motivation and effort [39,117], the use of visual and verbal feedback is recommended [6,42,106,117]. In cases where the optimal 1:1 coach-to-athlete ratio is not feasible (e.g., in larger samples), the athletes might give feedback to their training partner. ...
... Although this procedure is admittedly hard to realize in the field, individual thresholds to terminate an exercise set (e.g., ROM to downward acceleration <30 • ) should be implemented rather than predefining a fixed exercise volume. To improve the acute or chronic performance and quality of NHE execution by elevated motivation and effort [39,117], the use of visual and verbal feedback is recommended [6,42,106,117]. In cases where the optimal 1:1 coach-to-athlete ratio is not feasible (e.g., in larger samples), the athletes might give feedback to their training partner. ...
Article
Full-text available
ABSTRACT: The objective of this scoping review is to assess Nordic Hamstring Exercise quality (ANHEQ) of assessments and interventions according to the ANHEQ rating scales and to present practical recommendations for the expedient design and reporting of future studies. A total of 71 Nordic Hamstring Exercise (NHE) assessments and 83 NHE interventions were selected from the data sources PubMed, Scopus, and SPORTDiscus. Research studies which were presented in peer-reviewed academic journals and implemented the NHE during laboratory-based assessments or multi-week interventions met the eligibility criteria. NHE assessments analyzed force (51%), muscle activation (41%), knee angle kinematics (38%), and bilateral symmetry (37%). NHE interventions lasted 4–8 weeks (56%) and implied an exercise volume of two sessions per week (66%) with two sets per session (41%) and ≥8 repetitions per set (39%). The total ANHEQ scores of the included NHE assessments and interventions were 5.0 ± 2.0 and 2.0 ± 2.0 (median ± interquartile range), respectively. The largest deficits became apparent for consequences of impaired technique (87% 0-point-scores for assessments) and kneeling height (94% 0-point-scores for interventions). The 0-point-scores were generally higher for interventions compared to assessments for rigid fixation (87% vs. 34%), knee position (83% vs. 48%), kneeling height (94% vs. 63%), and separate familiarization (75% vs. 61%). The single ANHEQ criteria, which received the highest score most frequently, were rigid fixation (66% of assessments) and compliance (33% of interventions). The quality of NHE assessments and interventions was generally ‘below average’ or rather ‘poor’. Both NHE assessments and interventions suffered from imprecise reporting or lacking information regarding NHE execution modalities and subsequent analyses. Based on the findings, this scoping review aggregates practical guidelines how to improve the design and reporting of future NHE-related research.
... Although this procedure is admittedly hard to realize in the field, individual thresholds to terminate an exercise set (e.g., ROM to downward acceleration <30 • ) should be implemented rather than predefining a fixed exercise volume. To improve the acute or chronic performance and quality of NHE execution by elevated motivation and effort [39,117], the use of visual and verbal feedback is recommended [6,42,106,117]. In cases where the optimal 1:1 coach-to-athlete ratio is not feasible (e.g., in larger samples), the athletes might give feedback to their training partner. ...
... Although this procedure is admittedly hard to realize in the field, individual thresholds to terminate an exercise set (e.g., ROM to downward acceleration <30 • ) should be implemented rather than predefining a fixed exercise volume. To improve the acute or chronic performance and quality of NHE execution by elevated motivation and effort [39,117], the use of visual and verbal feedback is recommended [6,42,106,117]. In cases where the optimal 1:1 coach-to-athlete ratio is not feasible (e.g., in larger samples), the athletes might give feedback to their training partner. ...
Preprint
OBJECTIVE: Assessing Nordic Hamstring Exercise quality (ANHEQ) of assessments and interventions according to the ANHEQ rating scales and to present practical recommendations for the expedient design and reporting of future studies. DESIGN: Scoping review of 71 NHE assessments and 83 NHE interventions (12 of 131 full-text articles were applicable to both categories). DATA SOURCES: PubMed, MEDLINE and SPORTDiscus. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Research studies which were presented in peer-reviewed academic journals and implemented the NHE during laboratory-based assessments or multi-week interventions. RESULTS: The total ANHEQ scores of the analysed NHE assessments and interventions were 5.0±2.0 and 2.0±2.0 (median±IQR), respectively. Largest deficits became apparent for consequences of impaired technique (87% 0-point-scores for assessments) and kneeling height (94% 0-point-scores for interventions). The single ANHEQ criteria which received the highest score most frequently were rigid fixation (66% of assessments) and compliance (33% of interventions). CONCLUSIONS: The quality of NHE assessments and interventions was generally ‘below average’ or rather ‘poor’. Practitioners and scientists are encouraged to provide detailed information about their NHE modalities and about how their participants performed the exercise. The appropriate setup is suggested to be essential for best possible NHE performance and neuromuscular adaptations. NHE assessments should present comprehensive kinematic and kinetic data of supramaximal NHE performance, whereas NHE interventions should focus on exercise intensity and the implementation of facilitations. This scoping review aggregates practical guidelines how to improve the design and reporting of future NHE assessments and interventions to overcome the revealed limitations of current NHE-related evidences.
... Morbidity secondary to ACLR depends, in part, on the harvesting site, which also influences goals, milestones and progression of post-surgical rehabilitation. Functionally, harvesting from ST may result in persistent reduction of knee flexor muscle strength (Johnston, Feller, McClelland, and Webster, 2022) and altered muscle activation patterns (Arnason et al., 2014;Briem, Ragnarsdottir, Arnason, and Sveinsson, 2016). ...
Article
Full-text available
Background Ultrasound (US) imaging is used by physical therapists for diagnosis and assessment of musculoskeletal injury and follow-up Purpose The aim was to identify long-term effects of graft harvesting on hamstrings muscle mass among athletes who had undergone anterior cruciate ligament reconstruction (ACLR). Methods Twenty-eight participants (ages 18–55) were recruited: 18 with history of ACLR using semitendinosus (ST) autograft and 10 healthy controls. Images of the cross-sectional area (CSA) of ST and biceps femoris (BF) were captured at 30% and 70% of the distance from the ischial tuberosity to the popliteal crease. A mixed model ANOVA was used to identify inter-limb differences in the CSA of ST and BF at each location, for each group Results Inter-limb differences were found for the CSA of ST but not BF across both locations for the ACLR group, not controls (p < .001). Within the ACLR group, ST atrophy of the injured limb was relatively greater at the distal vs. proximal location (p < .001). Conclusion US imaging identified selective atrophy of ST on the injured side with no compensatory hypertrophy of BF. Specific rehabilitation may influence muscle mass of medial vs. lateral hamstrings muscle groups after ACLR using a ST graft, and monitored with US imaging.
... 2 3 The semitendinosus and/or gracilis tendons do not regenerate in ~30% of ACLR patients. 4 Moreover, ACLR patients often have long-term deficits in knee flexor and internal rotator strength, [5][6][7] as well as altered knee biomechanics, [8][9][10] muscle activation patterns [11][12][13] and knee function (patient-reported outcomes measure, PROM). 14 15 These chronic deficits in knee function are thought due, in part, to ...
Article
Full-text available
Introduction Anterior cruciate ligament (ACL) rupture is debilitating, often requiring surgical reconstruction. An ACL reconstruction (ACLR) using a tendon autograft harvested from the semitendinosus results in substantial injury to the donor muscle. Following ACLR, patients rarely return to their preinjury level of physical activity, are at elevated risk of secondary lower limb injuries and early onset knee osteoarthritis. To date, no randomised controlled trial has evaluated the efficacy of platelet-rich plasma (PRP) in aiding knee function and semitendinosus morphology of following ALCR. Methods and analysis This is a multicentre double-blind randomised placebo-controlled trial. Fifty-four ACLR patients aged 18–50 years will be randomised to receive either a single application of PRP (ACLR+) or placebo saline (ACLR) into the semitendinosus harvest zone at the time of surgery. All patients will undergo normal postoperative rehabilitation recommended by the attending orthopaedic surgeon or physiotherapist. The primary outcome measure is between-limb difference (ACLR compared with intact contralateral) in isometric knee flexor strength at 60 o knee flexion, collected 10–12 months postsurgery. This primary outcome measure will be statistically compared between groups (ACLR+ and standard ACLR). Secondary outcome measures include bilateral assessments of hamstring muscle morphology via MRI, biomechanical and electromyographic parameters during an anticipated 45° running side-step cut and multidirectional hopping task and patient-reported outcomes questionaries. Additionally, patient-reported outcomes questionaries will be collected before (baseline) as well as immediately after surgery, and at 2–6 weeks, 3–4 months, 10–12 months and 22–24 months postsurgery 10–12 months following surgery. Ethics and dissemination Ethics approval has been granted by Griffith University Human Research Ethics Committee, Greenslopes Research and Ethics Committee, and Royal Brisbane & Women’s Hospital Human Research Ethics Committee. Results will be submitted for publication in a peer-reviewed medical journal. Trial registration number ACTRN12618000762257p.
Article
Full-text available
The semitendinosus tendon is commonly harvested as graft tissue for anterior cruciate ligament reconstruction (ACLR). Although the semitendinosus tendon can regenerate following harvesting, ACLR results in substantial reductions in semitendinosus muscle size and length, potentially complicating electrode placement for electromyography. The purpose of this study was to assess whether the most commonly used electrode placement [recommended by the “Surface Electromyography for Non-Invasive Assessment of Muscles” (SENIAM) project] is appropriate for measuring semitendinosus electromyograms after ACLR. In nine participants (unilateral ACLR with a semitendinosus graft), B-mode ultrasonography was used to bilaterally determine (i) the semitendinosus muscle-tendon junction position and the state of tendon regeneration (latter for the ACLR leg only) and (ii) the anatomical cross-sectional area (ACSA) of the semitendinosus muscle at the SENIAM-recommended electrode placement site at rest and during isometric maximal voluntary contraction (MVC) at two knee joint angles. Depending on the contraction state and joint angle, the semitendinosus muscle had retracted past the recommended placement site in 33–78% of ACLR legs, but not in any contralateral legs. The ACSA of semitendinosus was smaller both at rest and MVC in the ACLR compared to contralateral leg. The ACSA for both legs decreased at MVC compared to rest and at deep compared to shallow knee flexion angles, likely due to sliding of the muscle under the skin. These results suggest SENIAM guidelines are likely unsuitable for recording surface electromyograms from the semitendinosus muscle after tendon harvesting for ACLR as the muscle of interest may not be within the electrode detection volume.
Thesis
Full-text available
Nowadays, suspension devices are one of the most widely used pieces of equipment to produce perturbation and strengthen most muscle groups globally. However, there is a lack of evidence of their effects on the lower limb. Thus, the main objective of this doctoral thesis was to quantify force production, muscle activity and the magnitude of perturbation in the Bulgarian squat and other lower extremity exercises under unstable conditions. Eighteen studies were analysed for a systematic review (study 1) and 75 physically active participants were recruited to perform the different cross-sectional studies on the effects of suspension devices, unstable surfaces, and mechanical vibrations (vibration platform and superimposed vibration) on lower limb exercises (studies 2-6). It was confirmed that lower body activation had only been previously investigated in the suspended hamstring curl (study 1). Position and pace (70 bpm) were determinants for the force exerted on the suspension strap in the Bulgarian squat (study 2). The suspension device in the Bulgarian squat increased the vertical ground reaction forces (study 3). The force production was higher on the device when the level of instability was low (study 3 and 4), but for muscle activity the device was just as demanding as a traditional exercise (study 3). Increased perturbation enhanced muscle activation (studies 3, 4, 5) and the magnitude of instability in the Bulgarian squat and barbell half-squat (studies 4 and 5). Thus, superimposed vibration on a suspension device becomes a challenge to increase the level of perturbation and improve strength, muscular endurance, and stabilisation (study 6). In addition, load cells are a suitable and practical tool to assess the forces exerted on suspension devices, and the use of an accelerometer makes it possible to determine the magnitude of the perturbation offered by different equipment providing instability by measuring the acceleration of the body's centre of mass.
Article
Background: Postural balance represents a fundamental movement skill for the successful performance of everyday and sport-related activities. There is ample evidence on the effectiveness of balance training on balance performance in athletic and non-athletic population. However, less is known on potential transfer effects of other training types, such as plyometric jump training (PJT) on measures of balance. Given that PJT is a highly dynamic exercise mode with various forms of jump-landing tasks, high levels of postural control are needed to successfully perform PJT exercises. Accordingly, PJT has the potential to not only improve measures of muscle strength and power but also balance. Objective: To systematically review and synthetize evidence from randomized and non-randomized controlled trials regarding the effects of PJT on measures of balance in apparently healthy participants. Methods: Systematic literature searches were performed in the electronic databases PubMed, Web of Science, and SCOPUS. A PICOS approach was applied to define inclusion criteria, (i) apparently healthy participants, with no restrictions on their fitness level, sex, or age, (ii) a PJT program, (iii) active controls (any sport-related activity) or specific active controls (a specific exercise type such as balance training), (iv) assessment of dynamic, static balance pre- and post-PJT, (v) randomized controlled trials and controlled trials. The methodological quality of studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. This meta-analysis was computed using the inverse variance random-effects model. The significance level was set at p < 0.05. Results: The initial search retrieved 8,251 plus 23 records identified through other sources. Forty-two articles met our inclusion criteria for qualitative and 38 for quantitative analysis (1,806 participants [990 males, 816 females], age range 9–63 years). PJT interventions lasted between 4 and 36 weeks. The median PEDro score was 6 and no study had low methodological quality (�3). The analysis revealed significant small effects of PJT on overall (dynamic and static) balance (ES = 0.46; 95% CI = 0.32–0.61; p < 0.001), dynamic (e.g., Y-balance test) balance (ES = 0.50; 95% CI = 0.30–0.71; p < 0.001), and static (e.g., flamingo balance test) balance (ES = 0.49; 95% CI = 0.31–0.67; p<0.001). The moderator analyses revealed that sex and/or age did not moderate balance performance outcomes. When PJT was compared to specific active controls (i.e., participants undergoing balance training, whole body vibration training, resistance training), both PJT and alternative training methods showed similar effects on overall (dynamic and static) balance (p = 0.534). Specifically, when PJT was compared to balance training, both training types showed similar effects on overall (dynamic and static) balance (p = 0.514). Conclusion: Compared to active controls, PJT showed small effects on overall balance, dynamic and static balance. Additionally, PJT produced similar balance improvements compared to other training types (i.e., balance training). Although PJT is widely used in athletic and recreational sport settings to improve athletes’ physical fitness (e.g., jumping; sprinting), our systematic review with meta-analysis is novel in as much as it indicates that PJT also improves balance performance. The observed PJT-related balance enhancements were irrespective of sex and participants’ age. Therefore, PJT appears to be an adequate training regime to improve balance in both, athletic and recreational settings.
Article
Studies comparing children and adolescents from different periods have shown that physical activity and fitness decreased in the last decades, which might have important adverse health consequences such as body fat gain and poor metabolic health. The purpose of the current article is to present the benefits of high-intensity multimodal training (HIMT), such as CrossFit, to young people, with a critical discussion about its potential benefits and concerns. During HIMT, exercise professionals might have an opportunity to promote positive changes in physical function and body composition in children and adolescents, as well as to promote improvements in mental health and psychosocial aspects. Moreover, this might serve as an opportunity to educate them about the benefits of a healthy lifestyle and overcome the perceived barriers for being physically active. In technical terms, the characteristics of HIMT, such as, the simultaneous development of many physical capacities and diversity of movement skills and exercise modalities might be particularly interesting for training young people. Many concerns like an increased risk of injury and insufficient recovery might be easily addressed and not become a relevant problem for this group.
Article
Changes in knee mechanics following anterior cruciate ligament (ACL) reconstruction are known to be magnified during more difficult locomotor tasks, such as when descending stairs. However, it is unclear if increased task difficulty could distinguish differences in forces generated by the muscles surrounding the knee. This study examined how knee muscle forces differ between individuals with ACL reconstruction with different graft types (hamstring tendon and patellar tendon autograft) and “healthy” controls when performing tasks with increasing difficulty. Dynamic simulations were used to identify knee muscle forces in 15 participants when walking overground and descending stairs. The analysis was restricted to the stance phase (foot contact through toe-off), yielding 162 separate simulations of locomotion in increasing difficulty: overground walking, step-to-floor stair descent, and step-to-step stair descent. Results indicated that knee muscle forces were significantly reduced after ACL reconstruction, and stair descent tasks better discriminated changes in the quadriceps and gastrocnemii muscle forces in the reconstructed knees. Changes in quadriceps forces after a patellar tendon graft and changes in gastrocnemii forces after a hamstring tendon graft were only revealed during stair descent. These results emphasize the importance of incorporating sufficiently difficult tasks to detect residual deficits in muscle forces after ACL reconstruction.
Article
Full-text available
Background Adequate neuromuscular control of the knee could be one element to prevent secondary injuries after an anterior cruciate ligament (ACL) injury. To assess neuromuscular control in terms of time, amplitude and activity, electromyography (EMG) is used. However, it is unclear which assessments using EMG could be used for a safe return to sports (RTS). Therefore, we aimed to summarize EMG-related assessments for neuromuscular control of the knee in adult patients after an ACL injury to decide upon readiness for RTS. Methods This systematic review followed guidelines of Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane recommendations. MEDLINE/PubMed, EMBASE, CINAHL, Cochrane Library, Physiotherapy Evidence Database (PEDro), SPORTDiscus and the Web of Science were searched from inception to March 2019 and updated in November 2020. Studies identifying electromyographic assessments for neuromuscular control during dynamic tasks in adult, physically active patients with an anterior cruciate ligament injury were eligible and qualitatively synthesized. Two independent reviewers used a modified Downs and Black checklist to assess risk of bias of included studies. Results From initially 1388 hits, 38 mainly cross-sectional, case-controlled studies were included for qualitative analysis. Most studies provided EMG outcomes of thigh muscles during jumping, running or squatting. Outcomes measures described neuromuscular control of the knee in domains of time, amplitude or activity. Risk of bias was medium to high due to an unclear description of participants and prior interventions, confounding factors and incompletely reported results. Conclusions Despite a wide range of EMG outcome measures for neuromuscular control, none was used to decide upon return to sports in these patients. Additional studies are needed to define readiness towards RTS by assessing neuromuscular control in adult ACL patients with EMG. Further research should aim at finding reliable and valid, EMG-related variables to be used as diagnostic tool for neuromuscular control. Moreover, future studies should aim at more homogenous groups including adequately matched healthy subjects, evaluate gender separately and use sport-specific tasks. Registration The protocol for this systematic review was indexed beforehand in the International Prospective Register of Systematic Reviews (PROSPERO) and registered as CRD42019122188.
Article
Full-text available
The semitendinosus-gracilis tendon autograft is often used to reconstruct the anterior cruciate ligament. Tendon regeneration appears to occur for most individuals in the short term, but little is known about the long-term effects of graft harvest. The purpose of this study was to describe the effect of semitendinosis-gracilis tendon graft harvest on muscle and tendon morphology at least five years following reconstruction in a case series. Magnetic resonance images were taken of the knees of three subjects at least five years following anterior cruciate ligament reconstruction. These subjects represented the different regeneration patterns at the time of return-to-sport. Muscle and tendon morphology were analyzed by calculating the volume, peak cross-sectional area, and length of the knee flexors. Muscle and tendon morphological changes were analyzed individually, and then in combination as defined as a knee flexor group. Muscle and tendon regeneration continued in those tendons that had begun regeneration at the time of return-to-sports in two subjects. There was significant additional muscle degeneration in those muscles whose tendons had not regenerated at the time of return-to-sports, in the remaining subject. Compensatory hypertrophy of the remaining knee flexors restored the knee flexor group to near preoperative peak cross-sectional area and volume across the each of the three case subjects. Knee flexor morphology at the time of return-to-sports foreshadowed the long-term outcome in the three studied subjects. Preservation of the tendon sheath in situ may play a role in tendon regeneration. When tendon regeneration did not occur, fatty infiltration of the muscle may be a worst-case outcome. Semitendinosus-gracilis muscle synergists demonstrated hypertrophy, perhaps in an effort to compensate for knee flexor group morphology deficits that existed after Semitendinosus gracilis tendon graft harvest. Semitendinosus and gracilis tendon harvest technique may play a role in regeneration. Additionally, knee flexor morphology at the time of return-to-sports may foreshadow the long-term outcome. prospective (longitudinal) cohort - level II.
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Ligament reconstruction is the current standard of care for active patients with an anterior cruciate ligament (ACL) rupture. Although the majority of ACL reconstruction (ACLR) surgeries successfully restore the mechanical stability of the injured knee, postsurgical outcomes remain widely varied. Less than half of athletes who undergo ACLR return to sport within the first year after surgery, and it is estimated that approximately 1 in 4 to 1 in 5 young, active athletes who undergo ACLR will go on to a second knee injury. The outcomes after a second knee injury and surgery are significantly less favorable than outcomes after primary injuries. As advances in graft reconstruction and fixation techniques have improved to consistently restore passive joint stability to the preinjury level, successful return to sport after ACLR appears to be predicated on numerous postsurgical factors. Importantly, a secondary ACL injury is most strongly related to modifiable postsurgical risk factors. Biomechanical abnormalities and movement asymmetries, which are more prevalent in this cohort than previously hypothesized, can persist despite high levels of functional performance, and also represent biomechanical and neuromuscular control deficits and imbalances that are strongly associated with secondary injury incidence. Decreased neuromuscular control and high-risk movement biomechanics, which appear to be heavily influenced by abnormal trunk and lower extremity movement patterns, not only predict first knee injury risk but also reinjury risk. These seminal findings indicate that abnormal movement biomechanics and neuromuscular control profiles are likely both residual to, and exacerbated by, the initial injury. Evidence-based medicine (EBM) strategies should be used to develop effective, efficacious interventions targeted to these impairments to optimize the safe return to high-risk activity.In this Current Concepts article, the authors present the latest evidence related to risk factors associated with ligament failure or a secondary (contralateral) injury in athletes who return to sport after ACLR. From these data, they propose an EBM paradigm shift in postoperative rehabilitation and return-to-sport training after ACLR that is focused on the resolution of neuromuscular deficits that commonly persist after surgical reconstruction and standard rehabilitation of athletes.
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Purpose The purpose of the study was to investigate the biomechanics of the knee and hip joint during handball-specific side-cutting on the dominant and non-dominant leg. Understanding the sports-specific biomechanics may improve prevention measures and post-injury treatment. Methods Twenty-four young female elite handball players performed 5 handball side-cutting manoeuvres on the dominant and non-dominant legs. The local maxima of the joint moments in each plane, during the initial 100 ms following foot contact, were collected. Results External knee moments of flexion, outward rotation and valgus—along with external hip moments of extension, abduction and internal rotation—were observed, coincidentally 30–40 ms after foot contact. No side-to-side asymmetries were found. The external moments observed support the injury mechanisms previously described in case studies of handball injuries. Conclusion The results underline the importance of implementing preventive exercises that increase activity of medial hamstrings, to match the external outward rotating knee moments and knee valgus moments, and increase activity of hip external rotators to match the external hip inward-rotating moment. Furthermore, the results may yield further information to the graft selection decision before ACL surgery. Level of evidence Diagnostic studies, Level II.
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Background: The advantages of hamstring tendon autografts for anterior cruciate ligament reconstruction are well known; however, concerns have arisen regarding the influence of hamstring tendon harvest on postoperative weakness in knee flexion. Purpose: To evaluate the influence of hamstring tendon harvest on knee flexion strength in patients undergoing anterior cruciate ligament reconstruction. Study Design: Prospective randomized study. Methods: Ninety patients were randomly assigned at surgery to undergo anterior cruciate ligament reconstruction with either a semitendinosus tendon autograft or a semitendinosus and gracilis tendon autograft. Quadriceps and hamstring muscle strength was tested before surgery and at 6, 12, and 18 months after surgery. Results: There was no significant difference in clinical results between the groups and neither group showed a significant decrease in isokinetic hamstring muscle strength. However, when the subjects' knees were at positions of 70degrees or more of flexion, both isokinetic and isometric measurements revealed a significant decrease in hamstring muscle strength in both groups. The strength in the group with semitendinosus and gracilis tendons was considerably less than that in the group with semitendinosus tendon alone at 18 months. Conclusions: Tendon harvest causes significant weakness of hamstring muscle strength at high knee flexion angles, but such weakness can be minimized if the gracilis tendon is preserved. (C) 2003 American Orthopaedic Society for Sports Medicine.
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Background: Rotational kinematics has become an important consideration after ACL reconstruction because of its possible influence on knee degeneration. However, it remains unknown whether ACL reconstruction can restore both rotational kinematics and normal joint contact patterns, especially during functional activities. Questions/purposes: We asked whether knee kinematics (tibial anterior translation and axial rotation) and joint contact mechanics (tibiofemoral sliding distance) would be restored by double-bundle (DB) or single-bundle (SB) reconstruction. Methods: We retrospectively studied 17 patients who underwent ACL reconstruction by the SB (n = 7) or DB (n = 10) procedure. We used dynamic stereo x-ray to capture biplane radiographic images of the knee during downhill treadmill running. Tibial anterior translation, axial rotation, and joint sliding distance in the medial and lateral compartments were compared between reconstructed and contralateral knees in both SB and DB groups. Results: We observed reduced anterior tibial translation and increased knee rotation in the reconstructed knees compared to the contralateral knees in both SB and DB groups. The mean joint sliding distance on the medial compartment was larger in the reconstructed knees than in the contralateral knees for both the SB group (9.5 ± 3.9 mm versus 7.5 ± 4.3 mm) and the DB group (11.1 ± 1.3 mm versus 7.9 ± 3.8 mm). Conclusions: Neither ACL reconstruction procedure restored normal knee kinematics or medial joint sliding. Clinical relevance: Further study is necessary to understand the clinical significance of abnormal joint contact, identify the responsible mechanisms, and optimize reconstruction procedures for restoring normal joint mechanics after ACL injury.
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Background: Patients usually return to pivoting sports between 6 months and 1 year after anterior cruciate ligament (ACL) reconstruction, but no matched study has so far examined 1-year return to sport rates in nonoperatively and operatively treated ACL-injured patients. Hypothesis: Anterior cruciate ligament-injured patients following a nonoperative treatment course, including recommendation of activity modification, will have lower return to pivoting sport rates than operatively treated patients 1 year after baseline testing/surgery, when matched by preinjury sports activity, age, and sex. Study design: Cohort study; level of evidence, 3. Methods: Sixty-nine nonoperatively treated ACL-injured patients were pair-matched with 69 operatively treated patients (n = 138), based on specific preinjury sport, age, and sex. Nonoperatively treated patients were recommended not to return to level I sports. Patients were defined as nonoperatively or operatively treated according to their status at follow-up. The baseline and follow-up testing included registration of sports participation, KT-1000 arthrometer measurements, 4 hop tests, and patient-reported outcome measures. McNemars test and paired t tests or Wilcoxon test were used to compare outcomes of nonoperatively and operatively treated patients. Results: No significant baseline differences were found. At 12.9 ± 1.2 months (mean ± standard deviation) after baseline testing (nonoperative) and 12.7 ± 1.2 months after surgery (operative), there was no significant difference in overall return to sport rates (nonoperative: 68.1%, operative: 68.1%, P = 1.00), or in return to level I sport rates (nonoperative: 54.8%, operative: 61.9%, P = .66). Nonoperatively treated patients who participated in level I sports before injury had a significantly lower return to sport rate (54.8%) than nonoperatively treated patients who participated in level II sports (88.9%, P = .003). The nonoperatively treated patients had significantly higher knee joint laxity, but significantly better hop test limb symmetry indexes, Knee Outcome Survey Activities of Daily Living scores, and International Knee Documentation Committee Subjective Knee Form 2000 scores. None of the functional differences was larger than the smallest detectable difference. Conclusion: Anterior cruciate ligament-injured patients following a nonoperative treatment course, including recommendations of activity modifications, and operatively treated patients did not have significantly different rates of returning to pivoting sports after 1 year in this pair-matched cohort study. Clinicians should be aware of a potentially high level of noncompliance to recommendations of activity modifications. Although these results show that it is possible for nonoperatively treated patients to return to sport after rehabilitation, future follow-ups are needed to examine whether these patients maintain sports participation over time, and what long-term consequences they may suffer regarding subsequent injuries and knee osteoarthritis.
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The present study examined the neuromuscular activation characteristics of the hamstrings during the 'Nordic' hamstrings exercise (NHE) and changes in the eccentric strength of the knee flexors with NHE training. Initially, the normalised root mean square electromyographic (EMG) activity of the hamstrings of both limbs during various phases (90-61°, 60-31° and 30-0° of knee extension) of the NHE were determined in 18 soccer players. Subsequently participants were randomly allocated to either a training (n=10) or control group. The isokinetic eccentric peak torques of the dominant and non-dominant limbs were recorded at 60, 120 and 240°/s pre- and post-training. The EMG values of both limbs were comparable (P=0.184) and greater EMG activity was recorded at more extended knee positions of the NHE (P=0.001). 4 weeks of NHE training significantly improved peak torque by up to 21% in all assessment conditions. Data indicate the hamstrings of both limbs are engaged identically during the NHE and training results in gains in the eccentric peak torque of the hamstrings of both limbs; these gains may augment the force that the hamstrings can withstand when forcefully stretched, attenuating injury risk.
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The risks for primary anterior cruciate ligament (ACL) rupture have been established. What is less well known is the risk of graft rupture after reconstruction and also the risk of a primary ACL rupture in the contralateral knee. To determine the long-term survival of the ACL graft and the contralateral ACL (CACL) after reconstruction and to identify factors that increase the odds of subsequent ACL injury. Case series; Level of evidence, 4. All patients having undergone primary ACL reconstruction in 1993 or 1994 by a single surgeon in a single unit were considered. Patients were contacted to complete a subjective interview by telephone or e-mail questionnaire at a minimum of 15 years after surgery. A total of 755 patients met the inclusion criteria, and ACL reconstruction was performed using a single-incision endoscopic technique with either autologous bone-patellar tendon-bone graft (BPTB; n = 314) or hamstring tendon graft (HT; n = 359) and metal interference screw fixation. Of these patients, 673 (89%) completed the questionnaire; 23% had sustained either a graft rupture or CACL rupture. Expected survival of the ACL graft was 95%, 93%, 91%, and 89% at a respective 2, 5, 10, and 15 years after reconstruction. Expected survival of the CACL was 97%, 93%, 90%, and 87%, respectively. Survival of the ACL graft was less favorable in men than in women (P = .007); ACL graft survival was not significantly different between the HT (88%) or BPTB (91%) groups (P = .149). Rupture of the CACL occurred twice as frequently as graft rupture in the BPTB group (graft survival, 84% vs 89%; P = .003). A positive family history of ACL rupture doubled the odds of both ACL graft and CACL rupture. The mean International Knee Documentation Committee subjective score at 15 years was 85. Return to preinjury sport levels was reported in 73% of patients, and 51% were still participating in strenuous or very strenuous activities at 15 years. Fifteen years after ACL reconstruction, expected survival of the ACL graft was 89% and expected survival of the CACL was 86%. Graft choice did not affect ACL graft rupture, but using BPTB increased the risk of CACL rupture compared with HT. Men had a less favorable survival rate of the ACL graft than did women, and a family history of ACL rupture increased the risk of both ACL graft and CACL rupture.
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The long-term effect of hamstring tendon harvest for anterior cruciate ligament (ACL) reconstruction on muscle morphology is not well documented. Our hypothesis was that harvest of the hamstring tendons for ACL reconstruction would result in persistent loss of volume and cross-sectional area of the gracilis and semitendinosus muscles. Magnetic resonance images were made of both limbs of ten patients nine to eleven years after they had ACL reconstruction with ipsilateral hamstring autograft. The volume of the individual thigh muscles bilaterally was calculated. The peak cross-sectional area and the cross-sectional area 7 cm proximal to the joint line was measured for the gracilis and semitendinosus muscles. Data were evaluated with use of the paired t test and Wilcoxon signed-rank test. The gracilis and semitendinosus muscles on the operatively treated side were evaluated for fatty infiltration and tendon regeneration. The mean volume on the operatively treated side was 54.2% of that on the noninvolved side for the gracilis muscle and 58.5% for the semitendinosus muscle. A 7% decrease in quadriceps volume and an 8% increase in the volume of the long head of the biceps on the operatively treated extremity were noted. The semimembranosus muscle and short head of the biceps muscle showed no difference in volume. The gracilis and semitendinosus muscles also showed a decrease in peak cross-sectional area, a decrease in the cross-sectional area 7 cm proximal to the joint line, and evidence of fatty infiltration. There was variable evidence of tendon or scar formation within the tendon bed, with most patients having some tissue that blended into either the sartorius muscle or medial gastrocnemius fascia at a level proximal to the joint line. At nine to eleven years after ACL reconstruction with ipsilateral hamstring autograft, the gracilis and semitendinosus muscles showed persistent atrophy on the operatively treated side with evidence of fatty infiltration and variability in tendon regeneration. There was also persistent atrophy of the quadriceps muscles and compensatory hypertrophy of the long head of the biceps. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.