MRI follow-up of conservatively treated meniscal knee lesions in general practice.

Abstract

To evaluate meniscal status change on follow-up MRI after 1 year, prognostic factors and association with clinical outcome in patients with conservatively treated knee injury.
We analysed 403 meniscal horns in 101 conservatively treated patients (59 male; mean age 40 years) in general practice who underwent initial knee MRI within 5 weeks of trauma. We performed ordinal logistic regression analysis to analyse prognostic factors for meniscal change on follow-up MRI after 1 year, and we assessed the association with clinical outcome.
On follow-up MRI 49 meniscal horns had deteriorated and 18 had improved. Age (odds ratio [OR] 1.3/decade), body weight (OR 1.2/10 kg), total anterior cruciate ligament (ACL) rupture on initial MRI (OR 2.4), location in the posterior horn of the medial meniscus (OR 3.0) and an initial meniscal lesion (OR 0.3) were statistically significant predictors of meniscal MRI appearance change after 1 year, which was not associated with clinical outcome.
In conservatively treated patients, meniscal deterioration on follow-up MRI 1 year after trauma is predicted by higher age and body weight, initial total ACL rupture, and location in the medial posterior horn. Change in MRI appearance is not associated with clinical outcome.

Full text

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Eur Radiol (2010) 20: 1242–1250
DOI 10.1007/s00330-009-1648-3
MUSCULOSKELETAL
Edwin H. G. Oei
Ingrid M. Koster
Jan-Hein J. Hensen
Simone S. Boks
Harry P. A. Wagemakers
Bart W. Koes
Dammis Vroegindeweij
Sita M. A. Bierma-Zeinstra
M. G. Myriam Hunink
Received: 23 June 2009
Revised: 6 October 2009
Accepted: 8 October 2009
Published online: 17 November 2009
# The Author(s) 2009.
This article is published with open access at
Springerlink.com
MRI follow-up of conservatively treated
meniscal knee lesions in general practice
Abstract Objective: To evaluate
meniscal status change on follow-up
MRI after 1 year, prognostic factors
and association with clinical outcome
in patients with conservatively treated
knee injury. Methods: We analysed
403 meniscal horns in 101 conserva-
tively treated patients (59 male; mean
age 40 years) in general practice who
underwent initial knee MRI within
5 weeks of trauma. We performed
ordinal logistic regression analysis to
analyse prognostic factors for meniscal
change on follow-up MRI after 1 year,
and we assessed the association with
clinical outcome. Results: On follow-
up MRI 49 meniscal horns had
deteriorated and 18 had improved. Age
(odds ratio [OR] 1.3/decade), body
weight (OR 1.2/10 kg), total anterior
cruciate ligament (ACL) rupture on
initial MRI (OR 2.4), location in the
posterior horn of the medial meniscus
(OR 3.0) and an initial meniscal lesion
(OR 0.3) were statistically significant
predictors of meniscal MRI appear-
ance change after 1 year, which was
not associated with clinical outcome.
Conclusion: In conservatively treated
patients, meniscal deterioration on
follow-up MRI 1 year after trauma is
predicted by higher age and body
weight, initial total ACL rupture, and
location in the medial posterior horn.
Change in MRI appearance is not
associated with clinical outcome.
Keywords Knee.Trauma.
Meniscus.Magnetic resonance
imaging.Conservative treatment.
Follow-up
Introduction
Traumatic knee injury is a frequently encountered
condition with a reported incidence of 5.3 per 1,000
patients in Dutch general practice annually [1]. In our
country, approximately 75% of patients with traumatic
knee injury are diagnosed and treated conservatively by
general practitioners. Most of these patients recover
without the need for referral to a specialist or surgery
[2].
Magnetic resonance imaging (MRI) is a well-established
and accurate diagnostic imaging technique for evaluation
E. H. G. Oei.M. G. M. Hunink (*)
Program for the Assessment
of Radiological Technology (ART
Program), Erasmus MC,
University Medical Center Rotterdam,
RoomEe21–40a,Dr.Molewaterplein50,
3015 GE Rotterdam, The Netherlands
e-mail: m.hunink@erasmusmc.nl
Tel.: +31-10-7043391
Fax: +31-10-7044657
Present address:
E. H. G. Oei.I. M. Koster.
M. G. M. Hunink
Department of Radiology,
Erasmus MC,
University Medical Center Rotterdam,
s-Gravendijkwal 230,
3015 CE Rotterdam, The Netherlands
E. H. G. Oei.M. G. M. Hunink
Department of Epidemiology,
Erasmus MC,
University Medical Center Rotterdam,
Dr. Molewaterplein 50,
3015 GE Rotterdam, The Netherlands
S. S. Boks.H. P. A. Wagemakers.
B. W. Koes.S. M. A. Bierma-Zeinstra
Department of General Practice,
Erasmus MC,
University Medical Center Rotterdam,
Burgemeester s’ Jacobplein 51,
3015 CA Rotterdam, The Netherlands
I. M. Koster.J.-H. J. Hensen.
S. S. Boks.D. Vroegindeweij
Department of Radiology,
Maasstad Ziekenhuis,
Olympiaweg 350,
3078 HT Rotterdam, The Netherlands
Present address:
S. S. Boks
Department of Radiology,
Diaconessenhuis Meppel,
Hoogeveenseweg 38,
7943 KA Meppel, The Netherlands

Page 2

of the knee joint [3, 4]. In most cases, MRI is performed in
the diagnostic work-up of persistent traumatic knee
complaints in search of treatable lesions, in particular
meniscal tears. MRI, therefore, is usually applied as a triage
test for targeted therapeutic arthroscopy [5–7].
Little is known about the appearance of meniscal lesions
on follow-up MRI after conservative treatment and its
correlation with clinical outcome. Several previous studies
have reported on follow-up MRI after surgical meniscal
repair [8–10], but in a recent systematic review of the
literature, Boks et al. [11] found only one small study on
the natural course of meniscal lesions evaluated by
sequential MRI [12].
The purpose of this study was to evaluate the natural
course of meniscal lesions on structured follow-up MRI in
the general practice population, to identify prognostic
factors at baseline for meniscal status change after 1 year,
and to assess the association of follow-up MRI findings
with clinical outcome.
Materials and methods
Patient selection and study design
We studied a subgroup of the prospective observational
HONEUR knee cohort study into acute and chronic knee
complaints in primary care in which 1,068 adult and
adolescent patients were included. The study design of
this cohort was described in detail by Heintjes et al. in a
previous paper [13]. The subgroup consisted of consecu-
tively included patients aged 18 to 65 years who visited
the general practitioner because of acute knee trauma
within the preceding 5 weeks [14]. Exclusion criteria
were: severe trauma necessitating immediate hospital
referral, a fracture demonstrated radiographically and
MRI contraindications. The study was approved by the
institutional review board of Maasstad Ziekenhuis,
Rotterdam, the Netherlands, and each patient provided
written informed consent.
Patients underwent initial MRI within 3 to 6 weeks of
trauma and follow-up MRI after approximately 12 months.
Immediately following both MRI examinations, an experi-
enced physiotherapist (HW) performed standardised phys-
ical examination, blinded for MRI findings, which
included specific meniscal provocation tests.
At baseline and 12 months after trauma self-reported
questionnaires were completed, recording a pain score
measured on an 11-point numeric rating scale ranging
from 0 (no pain) to 10 (unbearable pain) [15], Lysholm
knee function score [16], interval injuries, specialist
referralandwhetherornotanoperationhadbeenperformed.
At12monthswealsorecordedperceivedrecoverymeasured
on a seven-point Likert scale, ranging from ‘completely
recovered’ to ‘worse than ever’.
MRI technique and interpretation
MRI examinations were performed on a 1.0-Twhole-body
MRI unit (Signa Horizon LX, GE Medical Systems,
Milwaukee, USA) and a dedicated knee coil. We used an
MR imaging protocol as described in Table 1.
The anterior and posterior horns of both menisci were
scored separately for tears or degenerative lesions using the
grading system listed in Table 2. We also assessed the
presence or absence of coexistent cruciate ligament lesions.
Two independent readers (one senior radiology resident
(SB) and one experienced musculoskeletal radiologist
(DV)) assessed the initial MRI examinations and three
independent readers (two senior radiology residents
(EHGO and IMK) and one experienced musculoskeletal
radiologist (JHH)) evaluated the follow-up MRI using a
standardised case report form. In the case of discrepancies,
consensus was reached through discussion or the majority
opinion was used for analysis. MRI readers were blinded to
findings on physical examination, pain scores and func-
tional scores as reported on the questionnaires, but to
reflect clinical practice, the initial MRI examination was
available for comparison on follow-up MRI interpretation.
Unless there were abnormalities that required immediate
attention (e.g. fractures or tumours), initial MRI findings
were not reported to the general practitioner. Hence, the
treatment strategy was not influenced by the MRI findings.
Table 1 Parameters of the MR imaging protocol
Sequence Plane of
imaging
Repetition
time (ms)
Echo time (ms)Section
thickness (mm)
Matrix Field of
view (mm)
T1-weighted fast spin echo
Intermediate-weighted fast spin echo
T2-weighted fast spin echo
T2 gradient echoa
T2-weighted fat-suppressed fast spin echo
Intermediate-weighted fast spin echo
Sagittal
Sagittal
Sagittal
Coronal
Coronal
Axial
575
3,600
3,600
325
3,700
3,500
15
12
100
14
80
15
3
3
3
3
3
3
384×224
512×224
512×224
256×192
384×224
320×256
180×135
180×135
180×135
180×135
180×135
170×127.5
aThe flip angle was 30°
1243

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In the case of referral to a specialist, the specialist was able
to request the initial MRI report so as to avoid unnecessary
repetition of an MRI examination.
Data analysis
Patients who underwent an operation during the follow-up
period were excluded from the analysis. We performed per-
meniscal horn univariate and multivariate ordinal logistic
regression analysis using Stata/SE 10.0 for Windows
(StataCorp, College Station, Texas, USA) with the
separately available user-written Gologit2 macro [17]. As
the three possible ordinal outcomes, we defined an
improved, unchanged and deteriorated meniscal appearance
as reflected by the grading difference on follow-up versus
initial MRI. Performing ordinal logistic regression analysis
with three possible outcomes, two regression equations are
estimated with two regression coefficients per independent
variable. The first coefficient contrasted an unchanged or
deteriorated with an improved meniscal appearance, and the
second coefficient indicated a deteriorated versus an un-
changed or improved meniscal appearance.
The following independent variables were analysed:
age (continuous and dichotomised at age 40), sex,
physique as measured by body weight and body mass
index (continuous and dichotomised at 25 and 30 kg/m2),
sports injury as the trauma mechanism, baseline pain
score (continuous and dichotomised at 6 points), Lysholm
knee function score (continuous and dichotomised at 50
points), presence of a degenerative or traumatic meniscal
lesion on baseline MRI, a complete ACL rupture on the
initial MRI and three dummy variables to code the four
meniscal horns so as to assess the effect of location. We
also evaluated pain at passive flexion during initial
physical examination, as this was the only variable from
physical examination to show an association with menis-
cal tears in a previous study [18].
Variables with a p value of less than 0.10 in the
univariate analysis were included in the multivariate
analysis. In the multivariate analysis, a p value of less
than 0.05 was considered statistically significant.
We used the mean values of the other patients to impute
missing data on baseline pain score and Lysholm knee
function score in three patients and on pain score and
perceived recovery in seven and one patients, respectively.
As sports injury was strongly correlated with age and sex,
we performed a logistic regression analysis with these
variables to impute missing data on sports injury in six
patients. It has been demonstrated that imputation of
missing data reduces the risk of bias and is preferable over
complete case analysis [19, 20].
We assessed the association between change of
meniscal MRI appearance and clinical outcome, as
indicated by perceived recovery and change in pain
score at 12 months versus baseline. As these variables
were recorded on a patient level, we first created an
overall variable, reflecting per patient whether or not
meniscal deterioration was seen in any of the horns on
follow-up. We assumed that the rating of clinical
outcome is determined by the meniscal horn with the
least favourable change. Thus, a patient with improve-
ment of one meniscal horn and deterioration of another
horn on follow-up MRI was coded as deteriorated in the
overall variable. Subsequently, we analysed the associ-
ation between meniscal deterioration on a per-patient
level and perceived recovery and change in pain score
using Fisher’s exact test.
Because the exact procedure and effect on meniscal MRI
appearance was unknown in some patients who underwent
surgery, and to explore the effect of possible selection bias,
we performed a sensitivity analysis including the operated
patients.
As four meniscal horns per patient were analysed
separately, we corrected for the clustered nature of the
data using bootstrapping when testing for statistical
significance. Bootstrapping was performed by creating
1,000 replications of the dataset using sampling with
replacement and treating all of a patient’s observations as a
cluster (implying an independent identical distribution at
the patient level) [21]. Bias-corrected 95% confidence
intervals are reported.
Results
Of 263 potentially eligible patients, 134 fulfilled the
inclusion criteria and agreed to undergo additional MRI
Table 2 Grading system of meniscal lesions
Grade 0
Grade 1
Grade 2
Grade 3
Grade 4
Grade 5
Normal meniscal horn
Focal increased signal intensity within the meniscus
Linear band of increased signal intensity not extending to the articular surface
Horizontal meniscal tear
Longitudinal or vertical meniscal tear
Complex meniscal tear with a combination of multiple cleavage planes
For this study, grade 1 and 2 lesions were considered degenerative abnormalities. Signal abnormality extending to the articular surface was
used as a criterion for diagnosing a meniscal tear
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and physical examination at baseline. Follow-up MRI and
physical examination were performed in 117 patients.
Seventeen patients were not followed up because they
refused follow-up MRI and physical examination, or
because they had moved and we were unable to contact
them. A diagram indicating the patient selection and flow
through the study is presented in Fig. 1. Fifteen patients
were excluded from the analysis because they reported
having undergone surgery (14 arthroscopies and one ACL
reconstruction) during follow-up. The exact type of
arthroscopic procedure, however, was not always known.
Another patient was excluded because postoperative
findings associated with a partial meniscectomy of the
anterior horn of the lateral meniscus were unequivocally
present on follow-up MRI, although data on the procedure
were missing on the questionnaires. In one patient, only the
posterior horn of the medial meniscus was excluded
because of partial meniscectomy before the start of the
study. Thus, a total of 403 meniscal horns in 101 patients
(59 male, 42 female; mean age 40, range 18–63 years) were
analysed. Mean time between MRI examinations was
404 days (standard deviation 59.1, range 315–675 days).
There were no patients reporting a substantial knee injury
between baseline and follow-up MRI.
At baseline, there were 50 tears and 122 degenerative
lesions in 403 meniscal horns, most frequently in the
posterior horn of the medial meniscus (24 tears and 51
degenerative lesions). In nine patients a complete ACL
rupture was diagnosed on initial MRI, while no posterior
cruciate ligament tears were seen. The change in meniscal
MRI appearance after a 1-year follow-up is presented in
Table 3. A total of 336 meniscal horns (of which 231 were
normal) remained unchanged after 1 year. Twenty-seven
initially normal meniscal horns showed progression to a
degenerative lesion, but not into a tear. Six initially
degenerative lesions were scored as frank tears on follow-
up MRI, all of which were horizontal. Three new meniscal
tears, also exclusively of the horizontal type, were seen on
follow-up MRI without pre-existing abnormalities initially.
Eight meniscal tears showed progression and developed into
complex tears. On the other hand, eight degenerative lesions
and one horizontal tear on initial MRI were classified as
normal on follow-up MRI. Five initial meniscal tears no
longer extended to the articular surface on follow-up MRI
and were thus classified as a degenerative lesion. Two
initially complex meniscal tears showed improved morphol-
ogy on follow-up. Figure 2 shows an example of an initially
normal anterior horn of the lateral meniscus in which a
degenerative lesion had developed on follow-up MRI.
Table 4 presents the results of the univariate ordinal
logistic regression analysis for meniscal deterioration versus
improvement on follow-up MRI. Age (both continuous and
dichotomised at 40 years), baseline pain score 6 points or
higher, a meniscal lesion on initial MRI, complete ACL
rupture on initial MRI and location in the posterior horn of
the medial meniscus were statistically significant predictors
of change in meniscal appearance after 1 year, and were
included in the multivariate ordinal logistic regression
analysis. We also included body weight (continuous) as it
was of borderline significance when analysed univariately
(p=0.10). Baseline pain score was no longer statistically
significant when controlling for the other variables and was
therefore excluded from the final multivariate model
(Table5).Inthesensitivityanalysisof117patientsincluding
the 16 operated patients, we identified the same significant
variables as above with similar odds ratios and confidence
intervals (results not tabulated).
Correlation with clinical outcome
Regarding perceived recovery at 1 year, 28 and 67 patients
reported complete recovery and improvement, respectively,
whereas 2 patients experienced some deterioration. There
were no patients reporting substantial deterioration or a
condition that was worse than ever. Table 6 presents a
cross-tabulation of perceived recovery and meniscal MRI
appearance change. Forty-two patients with meniscal
Traumatic onset (n=351)Non-traumatic onset (n=717)
5 weeks after
trauma (n=309)
12 months: Follow-up MRI and physical examination (n=117)
Included in additional
MRI study (n=134):
Initial MRI and
physical examination
Exclusion criteria applicable /
refusal to participate (n=129)
> 5 weeks after
trauma (n=42)
Age 18-65 years
(n=263)
Adolescents /
elderly (n=46)
Lost to follow-up / refusal to
participate further (n=17)
Included in analysis (n=101)
Surgery during follow-up
(n=16)
HONEUR knee cohort:
All patients with new knee complaints consulting GP (n=1068)
<
Fig. 1 Flow diagram indicating the selection of subjects and the
flow of patients through the study
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deterioration on follow-up MRI reported improvement of
clinical outcome. Meniscal deterioration was not statisti-
cally significantly associated with clinical deterioration
measured by perceived recovery (Fisher’s exact test p value
0.50). Similarly, no statistically significant association was
found between meniscal deterioration and an increased
pain score at 12 months’ follow-up (Fisher’s exact test p
value 1.0, results not tabulated).
Discussion
We studied the natural course of meniscal knee lesions and
prognostic factors for meniscal appearance change on
follow-up MRI 1 year after trauma. Unlike most published
studies on meniscal abnormalities we studied a general
practice population, because in our country most patients
with traumatic knee injury are managed in primary care. To
our knowledge, our study is the first to evaluate the natural
course of meniscal abnormalities by using MRI follow-up
in a large study population in primary care.
The largest proportion of meniscal horns (57.3%)
were initially normal and remained normal on follow-up,
reflecting the primary care setting of this study. It is
possible that the proportion of normal menisci was larger
than in a hospital setting. We found that new degenerative
meniscal signal abnormalities on MRI may develop within
1 year of trauma. Conversely, in a number of menisci
initially scored as degenerative, we no longer observed
abnormal signal intensity on follow-up, suggesting that
smaller areas of intrameniscal signal abnormality may be
transient. All new meniscal tears were of the horizontal
type, and most of these were degenerative lesions initially.
This finding is consistent with previous studies suggesting
Table 3 Change in meniscal appearance on follow-up MRI compared with initial MRI
Lateral meniscus
anterior horn
(n=101)
Lateral meniscus
posterior horn
(n=101)
Medial meniscus
anterior horn
(n=101)
Medial meniscus
posterior horn
(n=100)
Total
(n=403)
Unchanged
Normal to normal
Grade 1 to grade 1
Grade 2 to grade 2
Horizontal tear to horizontal tear
Vertical tear to vertical tear
Complex tear to complex tear
New degenerative lesions and tears
Normal to grade 1 (new)
Normal to grade 2 (new)
Normal to horizontal tear
Progression of lesion complexity
Grade 1 to grade 2
Grade 1 to horizontal tear
Grade 2 to horizontal tear
Horizontal tear to complex tear
Vertical tear to complex tear
Improvement of lesion complexity
Grade 2 to grade 1
Horizontal tear to grade 2
Vertical tear to grade 1
Vertical tear to grade 2
Complex tear to horizontal tear
Normalisation of lesions
Grade 1 to normal
Grade 2 to normal
Horizontal tear to normal
56
12
1
5
3
1
71
9
0
6
0
0
85
5
3
2
1
0
19
24
16
10
7
0
231
50
20
23
11
1
11
2
2
7
0
0
2
0
0
5
0
1
25
2
3
0
1
1
0
3
1
0
0
3
0
0
0
0
0
0
4
0
4
2
0
5
1
5
5
3
0
1
0
0
0
1
0
0
0
0
1
0
0
0
0
1
1
1
2
1
3
2
1
2
1
2
0
0
2
0
1
1
1
0
1
1
0
6
2
1
Combinations that are not listed in the table were not observed in our study
1246

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that horizontal tears are usually a manifestation of degen-
erative disease rather than trauma [22, 23]. It is likely that
the new horizontal meniscal tears that were not associated
with previous abnormalities developed gradually from
normal to a degenerative lesion and subsequently to a
degenerative tear over the course of 1 year. Although the
number of cases where we found improvement of meniscal
tear morphology is relatively small, the findings suggest
that natural healing is possible. The natural healing
potential of menisci after conservative treatment was also
reported previously by Ihara et al. [24], but in this earlier
study arthroscopy was used instead of MRI to assess the
menisci.
In the multivariate ordinal logistic regression analysis,
deterioration of meniscal appearance after 1 year was
significantly predicted by higher age and body weight,
location in the posterior horn of the medial meniscus, and a
total ACL rupture on initial MRI. The last of these findings
is consistent with previous studies demonstrating a higher
incidence of meniscal tears in ACL-deficient unstable
knees [25, 26]. Presence of a meniscal lesion on initial MRI
was also statistically significant, but with an odds ratio
smaller than 1, indicating improvement if a meniscal lesion
was present initially, and again suggesting a natural healing
potential for meniscal lesions. The natural healing tendency
is, however, nullified if other predictive factors for
deterioration with an odds ratio greater than 1 are present.
The results indicate that patients with higher age and body
weight, initial total ACL rupture, and a lesion in the
posterior horn of the medial meniscus have a high risk of
meniscal deterioration 1 year after trauma in contrast to
patients without these risk factors who have a relatively
good prognosis.
Asthe HONEUR knee cohort was not aimed at assessing
treatment options for knee lesions, the management of our
patient population was not documented in detail. Conse-
quently, in some of the 14 patients who underwent
arthroscopy, it was unknown what procedure was
performed. Although most of these patients probably
underwent partial meniscectomy, the most common pro-
cedure in the setting of meniscal abnormalities, we were
not completely certain which component of MRI appear-
ance change could be attributable to surgery. To overcome
this problem and to obtain a homogeneous study popula-
tion, we only analysed conservatively treated patients. To
explore the possible effect of selection bias that may have
been introduced because the more severe cases necessitat-
ing surgery were not analysed, we performed a sensitivity
analysis that included the operated patients. This resulted in
an identical multivariate model with similar odds ratios,
indicating that our results were not influenced by the
exclusion of operated patients.
We also studied the association between change in
meniscal MRI appearance and clinical outcome. We found
no statistically significant association between meniscal
deterioration on follow-up MRI and worse clinical out-
come, as reflected by perceived recovery or change in pain
score. Many patients with deteriorated meniscal MRI
appearance still reported strong improvement or even
complete recovery. Our results are consistent with those of
Deutsch et al. [12], indicating that meniscal appearance on
follow-up MRI does not correlate with clinical outcome,
and suggesting that it is not useful to perform follow-up
MRI of the menisci to explain clinical deterioration. In light
of these results, we acknowledge that an increased score on
MRI grading systems based solely on worsened morphol-
ogy of meniscal signal abnormality, like that used in our
Fig. 2 Development of a degenerative lesion on follow-up MRI in a
patient who sustained a distortion of his right knee. a On the initial
MRI examination, a normal anterior horn of the lateral meniscus was
seen. b Follow-up MRI after 1 year demonstrated a linear band of
increased signal intensity that did not extend to the articular surface,
which was scored as a grade 2 degenerative lesion
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study, probably does not correlate with deteriorated clinical
meniscal status in many patients.
We used a 1.0-T MRI unit, but it has been shown that
lower magnetic field strength does not significantly reduce
diagnostic performance for meniscal tears [3]. Moreover,
as we studied meniscal lesions over time rather than the
diagnostic accuracy of the MRI technique, we expect that
this did not influence our results. We cannot completely
exclude the possibility of misinterpretation of meniscal
appearance change due to slight differences in imaging
Table 4 Results of the univariate ordinal logistic regression analysis for meniscal deterioration versus improvement on follow-up MRI
CovariableObserved frequency in study
population of 101 patients
(percentage)a
Odds ratio
(95% confidence interval)
P value
Age (continuous)
Age > 40 years
Male sex
Body weight
Body mass index (continuous)
Body mass index > 25
Body mass index > 30
Sports injuryb
Baseline pain score continuousc
Baseline pain score > 6 pointsc
Baseline Lysholm score continuousc
Baseline Lysholm score > 50c
Pain at passive flexion during physical examination
Meniscal lesion on initial MRI
Total ACL rupture on initial MRI
Location in posterior horn medial meniscus
40.0 years (11.8, 18–63)a
48 (48)
59 (58)
82.2 kg (16.0, 40–129)a
26.1 kg/m2(4.2, 17–40)a
58 (57)
18 (18)
53 (52)
4.4 (2.2, 0–10)a
34 (34)
66.8 (18.1, 18–100)a
79 (78)
62 (61)
142/403 horns (35)
9 (9)
100 (99)
1.02/year (1.00–1.04)
2.09 (1.16–3.76)
0.93 (0.58–1.50)
1.01/kg (1.00–1.03)
1.04 (0.98–1.09)
1.45 (0.89–2.36)
1.35 (0.74–2.48)
0.81 (0.50–1.30)
0.93 (0.85–1.03)
0.62 (0.36–1.06)
1.00 (0.98–1.01)
1.07 (0.64–1.80)
1.16 (0.73–1.84)
0.48 (0.23–0.98)
1.89 (1.12–3.21)
0.39 (0.14–1.07)
0.03
0.01
0.78
0.10
0.20
0.13
0.33
0.38
0.17
0.08
0.53
0.79
0.53
0.05
0.02
0.07
aFor continuous variables, we report mean (standard deviation, range)
bSix missing values were imputed
cThree missing values were imputed
Table 5 Results of the multivariate ordinal logistic regression analysis
Covariable Odds ratio95% confidence intervalP value
No change and deterioration versus improvement
Age (continuous, per decade)
Body weight (continuous, per 10 kg)
Presence of meniscal lesion on initial MRI
Presence of total ACL rupture on initial MRI
Location in posterior horn medial meniscus
Deterioration versus no change and improvement
Age (continuous, per decade)
Body weight (continuous, per 10 kg)
Presence of meniscal lesion on initial MRI
Presence of total ACL rupture on initial MRI
Location in posterior horn medial meniscus
1.33
0.85
0.30
2.35
0.74
1.07–1.68
0.63–1.15
0.12–0.72
1.14–4.82
0.16–3.46
0.01
0.29
0.01
0.02
0.70
1.33
1.22
0.30
2.35
2.98
1.07–1.68
1.01–1.49
0.12–0.72
1.14–4.82
1.20–7.40
0.01
0.04
0.01
0.02
0.02
For each independent variable, we first evaluated the applicability of the proportional odds assumption by using Gologit2’s ‘autofit’ option
and subsequently specified per variable whether or not the proportional odds assumption was to be applied. This resulted in a partial
proportional odds model, with two identical regression coefficients for variables meeting the proportional odds assumption and two
different coefficients for those that violated the assumption
1248

Page 8

plane orientation, but in our view the likelihood of
misclassification is low because identical pulse sequences
were used for initial and follow-up MRI, and in most cases
the presence of a meniscal tear was confirmed on multiple
contiguous images.
We conclude that the MRI appearance of meniscal
lesions 1 year after trauma is variable. In conservatively
treated patients, higher age and body weight, total ACL
rupture and location in the posterior horn of the medial
meniscus predict meniscal deterioration on follow-up MRI
after 1 year and, if present, these factors nullify the natural
healing potential suggested by our results. There is no
association between change in meniscal MRI appearance
and clinical outcome, and in many clinically recovered or
strongly improved patients, persistent abnormal or deterio-
rated meniscal appearance is seen.
Acknowledgements
and Mrs Caroline van Bavel-van Hamburg for their help in the data
management.
This study was funded in part by College voor Zorgverzekeringen
(Dutch Health Insurance Board).
The authors thank Ms Wibeke van Leeuwen
Open Access
Creative Commons Attribution Noncommercial License which
permits any noncommercial use, distribution, and reproduction in
any medium, provided the original author(s) and source are credited.
This article is distributed under the terms of the
Table 6 Perceived recovery and overall per-patient change in meniscal appearance on follow-up MRI
Perceived recovery
Some
improvement
Complete
recovery
Strong
improvement
UnchangedSome
deterioration
Total
MRI appearance improved or unchanged
MRI appearance deteriorated
Total
12
16
28
35
22
57
6
4
10
2
2
4
2
0
2
57
44
101
Table displays number of patients. There were no patients reporting substantial deterioration or a condition that was worse than ever
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