Keywords
revision ACL reconstruction - strength - arthrogenic muscle inhibition - donor site
morbidity - return to activity
Introduction
There are more than 200,000 new cases of anterior cruciate ligament (ACL) injury per
year in the United States [1]. This injury occurs
especially during the practice of pivoting contact sports such as soccer or
basketball, fighting sports such as Judo or Karate, and gymnastic or non-contact
sports such as skiing or volleyball [2]
[3]. To facilitate return to sports, many young athletes
undergo surgical intervention to reconstruct the ACL [4]. In the United States, from 1994 to 2014, the incidence rate of ACL
reconstruction increased from 30 to 75 per 100,000 person-year, particularly in
young people under 20 and in people over 40 years old [1]
[5]
[6].
Patellar or hamstring grafts are often proposed to reconstruct the ACL, with good
results in terms of knee laxity, isokinetic muscle strength recovery, knee pain and
return-to-sport [7]
[8].
However, a graft failure may occur after a new ipsilateral knee injury with a rate
estimated from 4 to 11% after return-to-play and from 7 to 16% if the patients are
under 25 [5]
[9]. Graft
failure is multifactorial and most frequently depends on a technical issue,
particularly because of tunnel mispositioning [10]
[11]
[12].
Young age (<25 years), female gender, high body mass index, and return to a
vigorous sport are identified as associated risk factors for an ACL revision [13]
[14]
[15]
[16]. The number of
graft failures is not well known because the injured knee is not always unstable
during daily life and some patients prefer to stop a risky sport rather than undergo
a new knee surgery to return to sport. The number of ACL revisions is estimated from
2 to 4% of ACL reconstructions [17]
[18]
[19]
[20]. Revisions of ACL reconstruction are unfortunately
associated with lower clinical outcomes when compared with primary reconstructions,
because of technical considerations and concomitant knee pathology as chondral
lesions and meniscal deficiencies [21]
[22]. The graft choice for revision ACL reconstruction
is always discussed by surgeons so as to obtain the best result for their patients.
The allograft needs a sterilization process and an irradiation, which may contribute
to weakening the mechanical properties of the graft, but without the inconvenient
of
the donor site morbidity [22]
[23]. The autograft is reasonable in athletes, depending on the graft used
during the primary ACL reconstruction [22]
[24]. If the initial procedure was a hamstring autograft
(HT), the revision is possible using an ipsilateral bone-patellar-bone autograft
(BPTB) or a contralateral hamstring graft [22]
[25]. Likewise, if the initial procedure was a BPTB
autograft, the revision is possible using a contralateral BPTB autograft or a
contralateral hamstring graft. The delay in return to sport may be longer after ACL
revision and will depend on the patient’s ability to regain symmetric strength to
complete a series of sport-specific tests [22]. After
primary ACL reconstruction the full recovery of the knee strength might in some
cases require up to 24 months [26]
[27]. A knee flexors deficit is measured after the
hamstring procedure, and an extensors deficit is measured after the
bone-patellar-tendon-bone procedure [26]
[27]. However, muscle strength recovery has not been
properly studied after revision of ACL reconstruction [28]. Indeed, recovery of muscle strength may be more difficult following
ACLR revisions due to the knee damage occurring during the tendon graft rupture
responsible for a new knee laxity and instability. The primary objective of this
study was therefore to assess the isokinetic knee extensor and flexor strength of
patients who underwent an ACLR revision surgery over a 9-month period to determine
if muscle strength recovery, defined as muscle strength symmetry, was similar after
revision of ACL reconstruction compared to a paired primary ACL reconstruction. The
secondary objectives were i) to compare the ipsilateral hamstring tendon procedure
with the contralateral BTPB procedure in cases of bone-patellar-tendon-bone
procedure revision, and ii) to compare the ipsilateral bone-patellar-tendon-bone
procedure with the contralateral hamstring tendon procedure in cases of hamstring
tendon procedure revision.
Materials and Methods
Population
The patients studied were selected in a retrospective cohort over a period
extending from January 2010 to December 2019. As far as the ACL revision group
was concerned, the patients were selected according to the following criteria:
i) one stage revision ACL reconstruction with contralateral HT or ipsilateral
BPTB, if the primary ACL surgery had used an HT graft, ii) one stage revision
ACL reconstruction with contralateral BPTB or ipsilateral HT graft, if the
primary ACL surgery had used an BPTB graft, and iii) isokinetic knee strength
follow-up performed at 4, 6 and 9 months post-surgery. Revision ACL
reconstruction with allograft, quadriceps tendon graft or other tendon grafts
were excluded because these types of procedures could not be compared with a
primary ACL reconstruction. Multi-ligament procedures and realignment
osteotomies were also excluded. The study also excluded patients who had
experienced recurrent knee instability during the follow-up, despite the
revision ACL reconstruction, and patients who had not had two or more isokinetic
evaluations over the 9-month postoperative period.
The patients with primary ACL reconstruction were selected in a retrospective
cohort set up between 2005 and 2019. This cohort included 953 patients and
followed knee isokinetic strength after primary HT or BPTB ACL
reconstructions.
Patients with revision of ACL reconstruction were matched with primary ACL
reconstruction patients according to sex, age (±2 years), weight (±2 kg) and
height (±2 cm) in order to compare them based on the type of grafts. The sports
activities were collected even though this parameter could not be used for data
matching, because too many different sports had been practiced before the ACL
rupture; in addition, the initial sport was not always the same one when the
rupture of the graft occurred. Similarly, matching depending on the surgeon was
not possible due to a cohort of patients operated on by several surgeons
specializing in knee surgery and working in different public or private
hospitals. During the follow-up, knee pain and post-operative complications were
collected because of their link with knee strength recovery after ACL
reconstruction [29].
All the patients gave their written consent to be involved in the study without
any financial retribution, and the isokinetic evaluation protocol corresponded
to the usual clinical follow-up of ACL reconstructions. The study protocol had
been approved by the Institutional Ethic Committee.
Standardized follow-up after ACL reconstruction
All the patients had an individual and “accelerated” rehabilitation program
originally described by Shelbourne et al. in 1992 for the BPTB procedure and by
De Carlo et al. for the hamstring procedure in 1994 [30]
[31]. These programs started on the
day after surgery, they consisted of encouragement for full active knee
extension and full range of motion, fast quadriceps activation depending on knee
swelling, and early weight bearing as soon as possible, with and without
crutches [30]
[31]
[32]
[33]. These rehabilitation programs were supervised by a
physiotherapist for an average of 40 outpatient sessions or for 30 inpatient
sessions (3 weeks with 2 sessions per day) followed by 10 out-patient sessions,
depending on the choice of the patients. At 2 months post-surgery, patients were
authorized to start cycling by the surgeon only if the knee was stable and
painless, and had full range of motion without swelling. At 4 months
post-surgery, isokinetic knee strength, functional and activity scales were
assessed by a sports medicine physician to encourage running, if the same
pre-cited clinical parameters had been reached and if the recovery of the
isokinetic quadriceps strength was superior to 40% (limb symmetry index
(LSI)+>+60%, which is calculated as follow: peak torque of ACL reconstruction
side / peak torque of contralateral knee side) x 100) to those of the
contralateral knee [26]
[34]. When the isokinetic quadriceps LSI was between 50 and 60%, the
continuation of cycling was proposed. Above 50% knee rest was requested with
stretching of the knee muscle and practice of swimming. At 6-month post-surgery,
the same clinical and isokinetic evaluation was performed and completed by a
hop-test to determine whether sports without pivot movements could be
authorized. After 9 months post-surgery, clinical examination, isokinetic knee
strength and hop-tests were assessed again, especially in patients with primary
or revision of ACL reconstruction who wanted to return to competitive
sports.
Isokinetic procedure
After a 10-minute cyclo-ergometer warm-up, isokinetic strength tests were
performed using a Humac Norm dynamometer (CSMI-Medimex, Ste Foy les Lyon,
France). Each subject was seated with a hip angle of 85 degrees. The mechanical
axis of the dynamometer was aligned with the lateral epicondyle of the knee. The
trunk and the thigh were stabilized with belts. The knee range of motion (ROM)
was 100 degrees (100° to 0°=full knee extension). Torque was gravity-corrected,
and the dynamometer recalibration was performed monthly according to the
manufacturer’s instructions. All the evaluation tests were conducted by the same
physician specializing in sports medicine. The two knees were evaluated,
beginning with the non-reconstructed knee side after instruction, as well as
verbal encouragements and visual feedback. After familiarization with the
isokinetic movement, the patients were tested over three repetitions of
concentric knee extension and flexion at 60°/s followed by five concentric
repetitions at 180°/s [35]. Thirty seconds of rest
were provided between the two series and 2 minutes between the two sides.
The judgment criteria were the quadriceps and hamstring limb symmetry index
(LSI), calculated at 60 and 180°/s for the revision ACL reconstruction group
according to the following formula: (Peak torque of Revision ACL reconstruction
side / Peak torque of contralateral knee side) x 100. The formula: (Peak torque
of Primary ACL reconstruction side / Peak torque of contralateral knee side) x
100 was used for the primary ACL reconstruction group. The reliability of
quadriceps and hamstring LSI reported previously in literature at 60 and 180°/s
are acceptable (ICCs: 0.43 to 0.78) [36].
Knee laxity
Knee laxity was measured in millimeters by the same physician at 9 months
post-surgery using a KT-1000 arthrometer (MEDmetric Corp., San Diego, CA, USA)
at 134 Newtons. The intra-examiner reliability of the knee laxity measurements
is good for 134 Newtons [37]. A Lachman test was
also performed. The Lachman test<5 mm of anterior displacement compared to
the opposite side indicates a negative test [38].
Functional parameter
Single leg hop distance was measured at 6 and 9 months after ACL reconstruction
because this test is usually incorporated in the return to sport criteria after
knee surgery [39]. The LSI was calculated
according to the formula: (Hop distance of the reconstructed knee / Hop distance
of the contralateral knee side) x 100 [40]. The
reliability of the hop LSI is good (ICCs: 0.92) with a greater change on the
operative limb [41].
Activity scales
The Lysholm scale was used to evaluate functional impairment due to the knee
symptoms during activity [42]. This scale of 100
points is considered from good to excellent for a scale between 84 and 100
points. The Tegner activity scale was used complementary to the Lysholm
functional scale to evaluate the level of work and sports activities [43]. This score was assessed during the
patient's medical interview in order to know the activity level before the
ACL rupture, and then during the follow-up, assessed at 4, 6 and 9 months
post-surgery. The Tegner activity scale is a one-item score which grades the
activity on a scale from 0 to 10. Level 3 represents a work-light labor like
nursing or sport-swimming or walking in forest and level 10 represents a
competitive sport such as soccer practiced at a national or international
level.
Statistical analysis
Statistical analysis was performed using the SPSS 23.0 software (Armonk, NY,
USA). The quantitative variables were expressed in mean and standard-deviation.
The categorical variables were expressed in median, maximum, minimum or
frequency. The normal distribution of groups and sub-groups was verified with a
Shapiro-Wilk test. First, the comparison between revision and primary ACL
reconstruction groups was assessed by a paired t-test and a McNemar
χ2 test. Second, sub-groups according to the type of graft were
compared using one-way ANOVA (6 groups x quantitative parameter) followed by a
Bonferroni or a Dunnet post-hoc test based on the variance homoscedasticity.
Results were considered significant at p<0.05.
Results
One hundred and ten patients with revision ACL reconstruction, 31 women (28,2%) and
79 men (71,8%) were included. The graft failure was determined clinically by a
surgeon, and confirmed by MRI, after a non-contact sports mechanism for 75 patients
out of 110 (68%) who presented knee instability. Patient age with revision ACL
reconstruction was 25.8±6.6 years and the median of delay between primary and
revision ACL reconstruction was 60 months (6 to 240 months). The duration between
graft failure and the revision surgery of ACL reconstruction was 294±514 days ([Table 1]). The type of revised ACL reconstruction
depended on the primary ACL procedure and on the surgeons’ choices according to
their habits to harvest ipsi- or contralateral knee tendon(s) for performing a new
graft. Sixty-six primary ACL reconstructions were revised with HT grafts and
compared to 66 primary ACL reconstructions with HT grafts. Contralateral HT graft
was used in 16 cases. Forty-four primary ACL reconstructions were revised using BPTB
graft and compared to 44 primary ACL reconstructions with BPTB graft. Contralateral
BPTB graft was used in 13 cases.
Table 1 Characteristics and follow-up of revision and primary
ACL reconstruction groups.
|
Revision ACL reconstruction (n=110)
|
Primary ACL reconstruction (n=110)
|
p
|
|
Age (year)
|
25.8±6.6
|
25.9±6.3
|
0.86
|
|
Weight (kg)
|
72.9±11.6
|
72.8±11.6
|
0.95
|
|
Height (cm)
|
170±21
|
169±19
|
0.88
|
|
Isokinetic follow-up (day):
|
|
|
|
|
1st evaluation (4 months)
|
128±37
|
121±14
|
0.21
|
|
2nd evaluation (6 months)
|
187±18
|
188±16
|
0.79
|
|
3rd evaluation* (9 months)
|
262±46
|
252±27
|
0.29
|
|
Reconstruction side:
|
|
|
|
|
Right knee
|
61 (55.5%)
|
64 (58.2%)
|
0.68
|
|
Left knee
|
49 (44.5%)
|
46 (41.8%)
|
|
|
Sport before ACL reconstruction:
|
|
|
|
|
Soccer
|
43 (39.1%) a
|
60 (54.5%) a
|
0.02
|
|
Basketball
|
14 (12.7%)
|
17 (15.6%)
|
|
|
Handball
|
10 (9.1%)
|
11 (10%)
|
|
|
Rugby
|
8 (7.3%)
|
5 (4.5%)
|
|
|
Fight Sport
|
5 (4.5%)
|
3 (2.7%)
|
|
|
Other sport
|
30 (27.3%)
|
14 (12.7%)
|
|
|
Meniscus procedure:
|
|
|
|
|
CM
|
36
|
29
|
0.39
|
|
LM
|
17
|
21
|
|
|
CM+++LM
|
6
|
6
|
|
|
Post-operative complications:
|
|
|
|
|
No
|
68 (61.9%)
|
70 (63.7%)
|
0.12
|
|
Swelling
|
11 (10.1%)
|
2 (1.8%)
|
|
|
Anterior Knee Pain
|
15 (13.5%)
|
20 (18.1%)
|
|
|
Posterior Knee Pain
|
6 (4.4%)
|
8 (7.3%)
|
|
|
Arthrofibrosis
|
11 (10.1%)
|
10 (9.1%)
|
|
|
Post-operative rehabilitation:
|
|
|
|
|
Inpatient
|
75 (68.2%)
|
61 (55%)
|
0.052
|
|
Outpatient
|
35 (31.8%)
|
49 (45%)
|
|
|
Activity at 4 months follow-up:
|
|
|
|
|
Rest
|
22 (20%)
|
10 (9.1%)
|
<0.01
|
|
Cycling
|
59 (53.7%) a
|
29 (26.4%) a
|
|
|
Running
|
7 (6.3%) a
|
70 (63.6%) a
|
|
|
Unknown
|
22 (20%)
|
1 (0.9%)
|
|
*n=91 patients in each group; a significant difference between
revision and primary ACL reconstruction.
In case of meniscal injury, suture or ablation were associated, depending on the type
of injury, with the ACL reconstruction or revision. Fifty-nine meniscal procedures
were associated to the revision ACL reconstruction ([Table
1]).
The various sports practiced before ACL reconstruction are listed in [Table 1], where soccer was the most practiced sport
before graft failure (39% of cases). Ninety-one revision ACL reconstruction patients
(82%) intended to return to their previous sport. Yet only 38 out of them (42%)
still maintained their goal at 9 months post-surgery after the isokinetic
evaluation. The others no longer had the wish to return to their previous sport.
Comparison between revision and paired primary ACL reconstruction
After matching method, the duration between ACL tear and the primary ACL
reconstruction and the duration between graft failure and the ACL revision were
not different (223±348 vs. 294±514 days; p=0.28) and the isokinetic follow-up
was comparable ([Table 1]).
The revision and primary ACL reconstruction groups were not different concerning
the association with a meniscal procedure and the occurrence of knee pain
complications ([Table 1]). A trend for more
inpatient rehabilitation was present after revision ACL reconstruction (p=0.052)
([Table 1]). More patients with revision ACL
reconstruction chose to practice cycling between 4 to 6 months post-surgery
compared to patients with primary ACL reconstruction who returned to running
more frequently at 4 months post-surgery (p<0.01) ([Table 1]).
The extensors and flexors knee strength deficits expressed in LSI were not
different between revision and primary ACL reconstruction ([Table 2]). At 4-, 6- and 9-months post-surgery,
the extensors isokinetic strength LSI at 60°/s were, respectively, 67±21, 78±19
and 84±26% for revision ACL reconstruction group and were, respectively, 66±16,
80±11, and 84±14% for the primary ACL reconstruction group (p=0.63, p=0.55, and
p=0.20, respectively). During the same follow-up, the flexors isokinetic
strength LSI at 60°/s were, respectively, 86±17, 93±25 and 87±16% for revision
ACL reconstruction group, and were, respectively, 86±14, 94±13 and 92±12% for
the primary ACL reconstruction group (p=0.96, p=0.66, and p=0.31).
Table 2 Comparison of isokinetic knee strength recovery,
Lysholm score, hop-test LSI and Tegner activity scale between
revision and paired primary ACL reconstruction at 4, 6 and 9 months
post-surgery.
|
Post-operative follow-up
|
Revision ACL reconstruction
|
Primary ACL reconstruction
|
p
|
|
4 months:
|
|
|
|
|
E60 LSI (%)
|
67±21
|
66±16
|
0.63
|
|
E180 LSI (%)
|
78±24
|
76±21
|
0.73
|
|
F60 LSI (%)
|
86±17
|
86±14
|
0.96
|
|
F180 LSI (%)
|
91±19
|
90±16
|
0.96
|
|
6 months:
|
|
|
|
|
E60 LSI (%)
|
78±19
|
80±11
|
0.55
|
|
E180 LSI (%)
|
84±16
|
85±11
|
0.80
|
|
F60 LSI (%)
|
93±25
|
94±13
|
0.66
|
|
F180 LSI (%)
|
95±25
|
96±15
|
0.69
|
|
9 months:
|
|
|
|
|
E60 LSI (%)
|
84±26
|
84±14
|
0.20
|
|
E180 LSI (%)
|
85±17
|
81±13
|
0.35
|
|
F60 LSI (%)
|
87±16
|
92±12
|
0.31
|
|
F180 LSI (%)
|
90±19
|
95±13
|
0.21
|
|
Lysholm score:
|
|
|
|
|
4 months post-surgery
|
92±10
|
95±8
|
0.02
|
|
6 months post-surgery
|
93±8
|
98±4
|
0.07
|
|
9 months post-surgery
|
93±10
|
97±6
|
0.24
|
|
Tegner activity scale:
|
|
|
|
|
Before ACL tear or graft failure
|
7 [4]
[5]
[6]
[7]
[8]
[9]
[10]
|
7 [5]
[6]
[7]
[8]
[9]
[10]
|
0.51
|
|
4 months post-surgery
|
4 [3]
[4]
[5]
[6]
|
4 [3]
[4]
[5]
[6]
|
0.62
|
|
6 months post-surgery
|
4 [3]
[4]
[5]
[6]
[7]
[8]
|
4 [3]
[4]
[5]
[6]
[7]
|
0.68
|
|
9 months post-surgery
|
5 [3]
[4]
[5]
[6]
[7]
[8]
|
5 [3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
|
0.67
|
|
Hop-test LSI (%):
|
|
|
|
|
6 months post-surgery (n=51)
|
95±2
|
89±4
|
0.13
|
|
9 months post-surgery (n=41)
|
94±8
|
90±8
|
0.23
|
|
Side-to-side knee laxity (mm):
|
|
|
|
|
9 months post-surgery (n=41)
|
2.5±2.4
|
2.1±2.2
|
0.78
|
Abbreviations: LSI: Limb Symmetry index; E60 LSI: Limb Symmetry index of
knee extensors at 60°/s; F180 LSI: Limb Symmetry index of knee flexors
at 60°/s.
No difference was found between revision and primary ACL reconstruction for the
hop-test at 6 (95±2% vs. 89±4%; p=0.13) and 9 months post-surgery (94±8% vs.
90±8%; p=0.23) and for the knee laxity at 9 months post-surgery (p=0.78) ([Table 2]). The Lysholm score was only
significantly lower in the revision ACL reconstruction group at 4 months
post-surgery, but with a mean of 92 points, already corresponding to a good
result ([Table 2]). The level of sports activity
recovery assessed by the Tegner activity scale was comparable between the two
groups during the post-operative follow-up ([Table
2]).
Comparisons according to the choice of graft
Ipsilateral HT or contralateral BPTB procedures after a
Bone-Patellar-Tendon-Bone graft failure
The recovery of the extensors and flexors strength was not different between
ipsilateral HT or contralateral BPTB procedures at 4-, 6- and 9-months
post-surgery ([Table 3]). The hop-test and
the Lysholm scores were comparable during the same follow-up ([Table 3]). Only the Tegner scale was 1 point
lower at 4 months post-surgery in case of contralateral BPTB procedure
([Table 4]). In case of ipsilateral HT,
knee strength recovery was comparable to that of a primary HT ACL
reconstruction ([Table 3]). In case of
contralateral BPTB, the extensors strength deficit was significantly lower
than that measured at 4 months post-surgery after a primary BPTB
reconstruction (LSI at 60°/s: 80±26 vs. 61±15%, respectively; p<0.05).
So, groups were different at 4 months post-surgery, but were comparable at 6
months (LSI at 60°/s: 80±23 vs. 74±13%, respectively; p+>+0.05) and 9
months (LSI at 60°/s: 95±26 vs. 81±15%, respectively; p+>+0.05)
post-surgery after BPTB graft failure.
Table 3 Isokinetic knee strength recovery, Lysholm
scale and hop-test at 4, 6 and 9 months based on the graft
procedures (ANOVA).
|
BPTB by HTi
|
BPTB by BTPBc
|
Paired primary BPTB
|
Paired primary HT
|
HT by HTc
|
HT by BPTBi
|
|
Graft or ACL rupture-surgery delay (day)
|
309±595
|
391±837
|
242±415*
|
213±275*
|
206±311
|
202±175
|
|
Follow-up
|
|
|
|
|
|
|
|
4 month (day)
|
120±13
|
116±27
|
122±13
|
120±16
|
118±17
|
129±11
|
|
6 months (day)
|
188±17
|
177±21
|
186±16
|
182±19
|
184±20
|
189±16
|
|
9 months (day)
|
251±49
|
248±30
|
255±32
|
260±36
|
269±62
|
268±51
|
|
Lysholm scale
|
|
|
|
|
|
|
|
4 months
|
94±9
|
86±14a
|
94±8
|
95±7 a,b
|
94±9
|
87±10 b
|
|
6 months
|
98±6
|
98±3
|
97±6
|
98±4
|
96±7
|
96±8
|
|
9 months
|
96±3
|
96±3
|
96±6
|
96±7
|
93±11
|
96±8
|
|
Hop-test (%)
|
|
|
|
|
|
|
|
6 months
|
93±3
|
95±5
|
94±8
|
91±5
|
95±2
|
92±6
|
|
9 months
|
92±1
|
94±2
|
92±6
|
92±7
|
92±4
|
92±5
|
|
Isokinetic testing
|
|
|
|
|
|
|
|
4 months
|
|
|
|
|
|
|
|
E60 LSI (%)
|
71±18 g
|
80±26 f
|
61±15 e,f,g
|
69±16 b,c
|
76±21 c,d,e
|
56±17 b,d
|
|
E180 LSI (%)
|
80±27 g
|
89±22 f
|
74±24 f,g
|
77±15 b,c
|
81±18 c
|
69±17 b
|
|
F60 LSI (%)
|
82±14 g,i
|
84±9
|
92±13 g,h
|
81±13 c,h
|
101±19 c,d,i
|
83±16 d
|
|
F180 LSI (%)
|
85±13 g,i
|
93±17
|
99±14 g,h
|
82±14 c,h
|
104±26 c,d,i
|
90±17 d
|
|
6 months
|
|
|
|
|
|
|
|
E60 LSI (%)
|
81±13
|
80±23
|
74±13 e,h
|
87±16 b,h
|
87±19 e
|
71±18 b
|
|
E180 LSI (%)
|
81±13
|
81±23
|
74±20 e,h
|
88±16 b,h
|
88±18 e
|
72±17 b
|
|
F60 LSI (%)
|
91±32
|
88±12
|
96±12 g,h
|
87±12 h
|
97±19
|
90±18
|
|
F180 LSI (%)
|
84±13 g,i
|
95±11
|
100±12 g,h
|
87±15 c,h
|
102±17 c,i
|
94±14
|
|
9 months
|
|
|
|
|
|
|
|
E60 LSI (%)
|
85±20
|
95±26 f,k
|
81±15 f
|
88±18
|
90±12
|
76±15 k
|
|
E180 LSI (%)
|
85±11
|
93±27
|
83±14
|
89±15
|
88±18
|
81±12
|
|
F60 LSI (%)
|
89±19
|
96±16
|
99±9 h
|
85±12 c,h
|
101±20 c
|
88±15
|
|
F180 LSI (%)
|
85±21 g,i
|
100±13
|
103±12 g,h
|
85±16 c,h
|
105±22 c,i
|
94±17
|
a Significant difference between HT primary and HT by
BPTBi; b Significant difference between HT primary and
BPTB by BPTBc; c Significant difference between HT
primary and HT by HTc; d Significant difference between
HT by HTc and HT by BPTBi; e Significant difference
between BPTB primary and HT by HTc; f Significant
difference between BPTB primary and BPTB by BPTBc; g
Significant difference between BPTB primary and BPTB by HTi;
h Significant difference between HT primary and BPTB
paired primary; i Significant difference between HT by
HTc and BPTB by HTi; j Significant difference between HT
by HTc and BPTB by BPTBc; k Significant difference
between HT by BPTBi and BPTB by BPTBc *Significant difference
between Primary ACL reconstructions (p-value<0.05).
Table 4 Tegner activity scale before ACL or graft
rupture during the 4 to 9 months follow-up based on the graft
procedures (ANOVA).
|
BPTB by HTi
|
BPTB by BTPBc
|
Primary BPTB
|
Primary HT
|
HT by HTc
|
HT by BPTBi
|
|
Before ACL injury
|
7 [5–10]
|
7 [5–10]
|
7 [5–9]
|
7 [5–10]
|
8 [6–10]
|
7 [5–10]
|
|
4 months post-surgery
|
4 [3–6] a
|
3 [3,4] a,b
|
4 [3–5]
|
4 [3–6] b
|
4 [3–5]
|
4 [3–5]
|
|
6 months post-surgery
|
4 [3–6]
|
4 [3–6]
|
4 [3–6]
|
4 [3–7]
|
4 [3–5]
|
4 [3–5]
|
|
9 months post-surgery
|
5 [4–8]
|
5 [4–7]
|
5 [4–8]
|
5 [4–9]
|
5 [5–7]
|
5 [4–7]
|
a Significant difference between BPTB by BPTBc and BPTB by
HTi; b Significant difference between BPTB by BPTBc and
Primary HT procedure.
Ipsilateral BPTB procedure or contralateral HT procedure after a
hamstring tendon graft failure
The extensors strength recovery after ipsilateral BPTB procedure was lower
than that observed after contralateral HT (LSI at 60°/s: 56 vs. 76% at 4
months; 71 vs. 87% at 6 months and 76 vs. 90% at 9 months, respectively)
([Table 3]). The flexors strength was
symmetric during the follow-up after contralateral HT procedure. The
hop-test, the Lysholm score and the Tegner scale were comparable during the
same follow-up ([Table 3] and [4]).
In case of ipsilateral BPTB procedure, the flexors strength deficit tended to
be higher compared to a primary BPTB procedure, and in case of contralateral
HT procedure, the flexors strength deficit tended to be lower compared to a
primary HT procedure.
So, contralateral HT procedure presented better knee strength recovery than
ipsilateral BPTB procedure during the first nine months post-surgery after a
HT graft failure.
Discussion
Revision ACL reconstruction is a technical challenge that aims to obtain at least
a
functional and stable knee for daily life activities [22]. Yet some young patients want to return to competitive sports that
are risky for their knees [44]. So the challenge is to
recover the knee strength symmetry essential for the general function, as well as
a
healthy knee for a return to sport [27]. However, only
a few studies have measured muscle strength recovery with an isokinetic dynamometer
or a similar device after revision of ACL reconstructions [38]. There are various grafts used for revision ACL reconstruction, and
the groups of patients are therefore difficult to study [45]. Only case series and case controls studies have reported muscle
strength deficiency after revision ACL reconstruction using autograft [28]
[38]
[45]
[46]
[47].
After a follow-up superior to 42 months, when ipsilateral BPTB graft was used for
ACL
revision using BPTB harvesting, the literature shows that the extensors strength and
the flexors strength LSI at 60°/s ranged from 82 to 103% and from 88 to 96%,
respectively [45]
[46]
[47]. These results were comparable to
those reported by Dauty et al. in 2014 from a 12-month post-surgery follow-up (88
and 94%, respectively) for the ipsilateral BPTB procedure after primary hamstring
graft [28]. Our current results were lower (76 and
88%), perhaps because a 9-month post-surgery follow-up was too short a delay to
recover full knee strength as part of a complete recovery.
After pairing method, based on the type of graft, the extensors strength and the
flexors strength LSI at 4, 6 and 9 months were similar between revisions and primary
ACL reconstructions. Gifstad et al. found the same results at 90 months of follow-up
between 56 ACL revisions (31 BPTB and 25 HT grafts) and an unmatched control group
of primary ACL reconstructions (44 BPTP and 8 HT grafts) [38]. Our current results were 5% lower (84 and 87%); this is possibly
because a 9-month post-surgical follow-up may be insufficient to assess a complete
recovery of knee strength compared to the 90-month follow-up described by Gifstad
et
al. Yet the originality of our study was to show the difference of recovery during
the first month post-surgery based on the type of grafts used for the revision ACL
reconstruction. To explain knee strength LSI during the first 9 months after ACL
reconstruction and revision, two hypotheses can be made. First, the arthrogenic
muscle inhibition (AMI), which predominated on the knee extensors (quadriceps) of
the operated knee, depends on the post-operative knee effusion [48]
[49]
[50]. When joint effusion was experimentally induced by
intraarticular infusion of physiological saline into the knee (30 to 60 ml), vastus
medialis and lateralis muscle activity decreased [48].
After knee joint aspiration, an increase of isometric knee extensor torque and
muscle electromyographic activity was reported [49],
without any evidence of a supraspinal contribution to quadriceps AMI [50]. Second, the donor site morbidity may cause a
lasting strength deficit for more than 24 months on the knee extensors in case of
BPTB graft or on the knee flexors in case of HT graft [27]
[51]. The muscle tendon properties of
the semitendinosus and the gracilis muscles were reported substantially altered in
65% of the cases after harvesting, and these alterations contributed to a knee
flexor weakness on the surgical limb [51]. In 1995,
Yasuda et al. had already shown this phenomenon when they studied the knee flexors
strength after primary ACL reconstruction with ipsilateral or contralateral HT [52]. A decreased flexors muscle strength was reported 9
months after surgery on the harvest knee side. In the same way in 2000, Shelbourne
et al. had shown that the quadriceps muscle strength was greater in the primary
reconstructed knee at 1, 2 and 4 months after contralateral BPTB procedure compared
to ipsilateral BPTB procedure [53].
The authors concluded that the use of the contralateral patellar tendon could help
restore more quickly strength symmetry than the ipsilateral patellar tendon graft.
The return to full capacity in sport was faster without compromising ultimate
stability [53]. Moreover, the consequences on the
donor site after the first ACL reconstruction could last for a long time after
surgery [28]. Indeed, that may occur when the same ACL
reconstruction technique is chosen using the contralateral tendon of the primary ACL
reconstruction. Symmetrical knee strength may also be easier to obtain because of
a
previous strength deficit due to the primary ACL reconstruction, which may be
comparable to the strength deficit secondary to revision procedure.
According to our results, after BPTB graft failure, the revision ACL reconstruction
with ipsilateral HT graft causes a low extensors strength deficit due perhaps to the
quadriceps AMI and a high and lasting flexors strength deficit in the reconstructed
knee side equivalent to a primary HT graft procedure. If a contralateral BPTB graft
is chosen, a quadriceps AMI explains the extensors strength deficit on the
reconstructed knee side and the contralateral patellar tendon graft accounts for an
extensors strength deficit in the none-reconstructed knee side. The extensors
strength symmetry is also easier to obtain, and no flexors strength deficit is
present.
After HT graft failure, the revision ACL reconstruction with ipsilateral BPTB graft
causes a high extensors strength deficit due to the quadriceps AMI and to the new
patellar tendon ipsilateral donor site morbidity on the reconstructed knee side. A
flexor strength deficit of 10% or more is often present because of the previous HT
graft procedure [28]. If a contralateral HT graft is
chosen, a quadriceps AMI accounts for a low extensor strength deficit on the
reconstructed knee side and a lasting flexor strength deficit on the
non-reconstructed knee side. The flexor strength symmetry is also easier to obtain
if a previous flexor strength deficit is present on the reconstructed knee side
because of the previous morbidity of the primary HT graft.
The rehabilitation program apparently did not have any influence on knee strength
recovery even if the groups were not matched according to this specific parameter.
Rousseau et al. have already shown that inpatient and outpatient rehabilitations
were similar in terms of knee strength recovery after primary ACL reconstruction
[54]. Moreover, rehabilitation exercises remained
necessary in the event of knee pain complications after ACL reconstruction.
Likewise, aerobic physical activities performed between 4 to 6 months after ACL
reconstruction did not improve knee strength recovery [55]. Furthermore, it seems likely that patients, who had undergone two
surgeries on the same knee, might have reconsidered their athletic ambitions. Thus,
the knee was not negatively impacted by a highly intensive rehabilitation program,
which is often responsible for greater deficits in isokinetic strength because of
overloaded adaptation capacities of the operated knee [29]. Most of the time, patients think that only exercises improve knee
strength, while the absence of complications is a major factor in the normalization
of side-to-side knee strength.
This study has some limitations because of the low number of patients in the
sub-groups, especially for the revision ACL reconstruction group using contralateral
graft. In fact, the indication for the use a contralateral graft is not clear and
depends on the personal habits and experience of the surgeon who may prefer HT or
BPTB grafts because they are two comfortable routine procedures [56]
[57]. The
contralateral procedure is not common, perhaps due to fear of damaging the healthy
knee [25]. Because of the small number of revision ACL
reconstructions using contralateral graft, new studies including more cases are
necessary to obtain more reliable results. The short follow-up of 9 months
corresponds to a second limitation because full knee strength may not be fully
recovered at this endpoint. This limitation can be explained by our local habits
which proposed only isokinetic testing if the patients with revision ACL
reconstruction wanted to return to a competitive sport. Although 91 patients with
revision ACL reconstruction (82%) intended to return to their sport before surgery,
only 38 out of them (42%) maintained their goal at 9 months post-surgery after the
isokinetic evaluation. Yet we can consider that only a 5% strength increase could
have been expected on the reconstructed knee, if the postoperative follow-up had
been prolonged for more than 24 months, according to the results of literature [38]. Another limit is the lack of exact knowledge
regarding the degenerative state of the operated knee, such as early osteoarthritis
lesions, which were not assessed in this study. However, the knee strength recovery
being similar to that of the primary ACL reconstruction seems to show that the early
knee strength recovery might not be linked to the presence or absence of
degenerative lesions. The impact of knee pain on knee strength recovery was not due
to a limited sample size, even if the number of pain complications was similar in
the revision group and in the paired primary ACL reconstruction group. More studies
with a large sample will help validate these findings after making adjustments for
these potential covariates.
Finally, our results cannot be applied to other grafts such as quadriceps or other
tendon grafts or allografts, for example. Indeed, as their characteristics are
different, their consequences in terms of early knee strength recovery would
undoubtedly be different.
Conclusion
According to the concept of the knee strength symmetry recovery, results after
revision ACL reconstruction were similar to those measured after primary ACL
reconstruction using the same technique. Based on this parameter, after BPTB graft
failure, ipsilateral HT procedure or contralateral BPTB procedure could be chosen
indifferently, although many other criteria must be considered. After HT graft
failure, the contralateral HT procedure was better than the ipsilateral BPTB
procedure, but only for the first 6 months post-surgery. These results seemed to
depend on a non-lasting quadriceps arthrogenic muscle inhibition and on a lasting
donor site morbidity, potentially concerning the previous graft and the new graft.
Finally, this isokinetic knee strength recovery was relevant for the short follow-up
of revision ACL reconstructions when discussing the possibility of returning to a
sport.
