Keywords
femoracetabular impingement - arthroscopy - hip
Introduction
Since Beck et al[1] described the chordal lesion mechanism due to CAM-type femoroacetabular impingement
(FAI), in which chondral delamination results from the shear forces caused by the
alteration of the femoral head-neck normal morphology, numerous studies have been
carried out to enhance the diagnosis and early treatment of these lesions, as well
as to evaluate the outcomes from the surgical treatment, including techniques such
as microfracture, chondrocyte implantation, and fibrin glue, which are dependent on
the poor regeneration capacity of the chondral tissue.[2]
It is well-known that patients with hip osteoarthritis have a high risk of early conversion
to arthroplasty[3] and arthroscopic treatment failure,[4] and that isolated chondral lesions of the hip are factors of poor prognosis for
surgical treatment.[5]
[6]
[7] Chondral delamination frequently occurs in patients with FAI.[1]
[8]
[9]
[10]
[11] Its diagnosis, however, is often made only during the surgical procedure and, sometimes,
patients with nonluxuriant symptomatology present extensive cartilaginous lesions.
There is already consensus that some factors are associated with chondral lesions.
In addition to the preoperative finding of these lesions in magnetic resonance imaging
studies,[12] the presence of arthrosis in grade II or higher of Tonnis,[13] the CAM-type impingement is directly associated with the development of chondral
flaps.[14] Studies also demonstrate the association of chondral lesions of the hip with age
and the male gender.[1]
[4]
[13]
In transoperative diagnosis, classification systems are used to determine articular
cartilage involvement. The classic classification of Outerbridge,[15] deemed universal since it is used to classify chondral lesions in various joints,
is moderately reproducible and reliable.[16] The Beck system was developed to classify chondral lesions during controlled hip
dislocation for FAI treatment.[17] More recently, the arthroscopic classification of Haddad[18] ([Table 1]), was specifically described for hip lesions found during the arthroscopic procedure
and it is related to chondral lesion progression. This classification system determines
lesion location in quadrants, the presence of chondrolabral junction damage and, finally,
the extent of the lesion. Chondrolabral junction damage is defined by lesion progression,
where 0 is absence of lesion, grade I is defined by the presence of a wave sign ([Fig. 1A]), grade II is the damage to the chondrolabral junction, but with no acetabular cartilage
delamination ([Fig. 1B]), and grade III is a lesion with subchondral bone cartilage detachment ([Fig. 1C]). Finally, in grade IV, there is subchondral bone exposure ([Fig. 1D]). This classification presents the best intra- and interobserver correlation when
compared with the two aforementioned systems.[17]
Table 1
|
Grade 0
|
No chondral lesion.
|
|
Grade I
|
Wave sign, loss of subchondral bone fixation.
|
|
Grade II
|
Obvious chondrolabral junction rupture, but no evidence of cartilage delamination
from the subchondral bone at probe exploration.
|
|
Grade III
|
Delamination with cartilage separation from the subchondral bone.
|
|
Grade IV
|
Exposed subchondral bone.
|
Fig. 1 (A) Grade I - wave sign; (B) Grade II - chondrolabral junction damage with no cartilage
delamination; (C) Grade III - subchondral bone cartilage detachment; (D) Grade IV
- subchondral bone exposure.
No specific maneuver can assist the diagnosis of isolated chondral lesions of the
hip, since the articular cartilage has no nociceptors, and it may take time until
it causes mechanical symptoms or joint irritation.[17] The early management of these lesions, associated with FAI correction, is directly
related to the outcome of the arthroscopic treatment.[19] Thus, the identification of patients susceptible to deep articular cartilage lesions
is decisive for defining the timing of the surgical treatment and to manage the postoperative
expectations of the patient, especially regarding the return to sports activities.
The present study aims to evaluate if there is a relationship between the presence
of deep chondral lesions in the hip during arthroscopic FAI treatment and to associate
them to the preoperative nonarthritic hip score (NAHS) – Brazil[20] and to the preoperative alpha angle measurements, to the acetabular coverage angle,
to the radiological Tonnis classification, and to the age and gender of the patients.
Material and Methods
The present study was approved by the Ethics Committee of the Universidade de Passo
Fundo, state of Rio Grande do Sul, Brazil, under the number 1.749.565, according to
Resolution 466/12 of the Brazilian Health Council. The present study included 110
patients (125 hips) consecutively submitted to hip arthroscopy between May 2016 and
May 2017 by a single surgeon, and who were prospectively evaluated for the presence
of chondral lesions. Patients submitted to arthroscopy for the treatment of conditions
other than FAI, those with a history of previous hip or spine surgeries, those presenting
arthrosis classified as grade II of Tonnis at panoramic pelvic radiographs at the
time of the surgery, and those with no functional scores collected on the day of the
surgery were excluded from the initial sample. Thus, the final sample consisted of
92 patients (107 hips) submitted to treatment for mixed impingement (78%) or isolated
CAM impingement (22%) and presenting pelvic radiographs classified as grades 0 and
1 of Tonnis. The patients were submitted to a questionnaire for functional evaluation
on the day of the surgery; in addition, their radiological measurements were taken,
and their arthrosis was classified according to the Tonnis criteria. An anteroposterior
(AP) hip radiography with controlled rotation (pubic symphysis aligned to the coccyx)
and tilt (distance from the pubic symphysis to the sacrococcygeal junction) was used
to determine both the Wiberg acetabular coverage angle and the Tonnis classification
of hip arthrosis. The alpha angle was measured in 45° Dunn views. The data was tabulated
with Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) and the statistical
analysis was performed with IBM SPSS Statistics for Windows, Version 22.0 (IBM Corp.,
Armonk, NY, USA).For the analysis, the sample units were the hips classified according
to the severity of the chondrolabral lesion in two groups according the depth of the
chondral lesion, but regardless of its location and extent, following the arthroscopic
classification of Haddad[18]; as such, one group was comprised by hips with no chondral or superficial, grades
I to II lesions, while the other group was comprised by hips with deep, grades III
and IV of Haddad[18] lesions. The associations between lesion grade and symptom score, lateral coverage
angle, alpha angle, and age were tested per a variance analysis with a classification
criterion. The associations between lesion grade and gender or Tonnis classification
were evaluated using the chi-squared test. Tests with a probability value < 0.05 were
considered statistically significant.
Results
The final sample consisted of 107 joints from 92 patients; 67 hips (62.6%) were from
male patients, and 59 hips (55.1%) were left hips; in addition, the average age of
the patients was 33.56 ± 7.4 years old. Regarding the severity of the lesion, 11 hips
presented grade IV lesions, and 14 hips had grade III lesions, totaling 25 patients
(23.4%) in the deep lesion group. In the group of patients with mild lesions, 13 (12.1%)
individuals were grade 0 (no chondral lesion), 24 (22.4%) had grade I chondral lesions,
and 45 (42.1%) presented grade II lesions, totaling 82 hips (76.6%). Regarding the
presence of radiographic changes according to the Tonnis criteria, 80 hips (74.8%)
were classified as grade 0, while 27 (25.2%) hips were classified as grade I.
Male patients undergoing arthroscopic treatment for FAI had higher NAHS functional
scores and a greater proportion of deep chondral lesions compared with female patients;
65.6 ± 19.6 versus 49.3 ± 21.6, p < 0.001, and 23 (34.3%) versus 2 (5.0%); p = 0.001, respectively.
It was observed that patients with deeper lesions had significantly higher NAHS scores
than those with more superficial lesions (67.9 ± 19.4 versus 57.0 ± 21.9; p = 0.027). There was no statistically significant difference between groups with superficial
and deep lesions regarding the Wiberg lateral coverage angle and the alpha angle (35.1 ± 8.4
versus 33.1 ± 6.6; p = 0.271; and 66.3 ± 8.5 versus 69.0 ± 7.0; p = 0.155, respectively). Likewise, there was no statistically significant difference
in the age of patients with superficial or deep chondral lesions (33.0 ± 7.6 versus
35.0 ± 7.4; p = 0.253). On the other hand, the proportion of Tonnis 1 classification was significantly
higher among deeper chondral lesions (15, 60.0%), compared with more superficial lesions
(12 [14.6%]; p < 0.001). The prevalence of deep chondral lesions was higher among hips classified
as Tonnis 1 compared with Tonnis 0 hips (15 [55.6%] versus 10 [12.7%], prevalence
ratio 4.4; p < 0.001) ([Table 2]).
Table 2
|
Absent or mild lesion (n = 82)
|
Deep lesion (n = 25)
|
p-value
|
|
Gender (male)
|
44 (65.7%)
|
23 (34.3%)
|
0.001
|
|
Age (years old)
|
33.0 ± 7.6
|
35.0 ± 7.4
|
0.253
|
|
NAHS
|
57.0 ± 21.9
|
67.9 ± 19.4
|
0.027
|
|
Alpha angle
|
66.3 ± 8.5
|
69.0 ± 7.0
|
0.158
|
|
CE angle
|
35.1 ± 8.4
|
33.1 ± 6.6
|
0.288
|
|
Tonnis I
|
10 (12.7%)
|
15 (55.6%)
|
< 0.001
|
Discussion
The presence of chondral lesions in patients undergoing hip arthroscopy for FAI treatment
is a frequent finding, documented in between 45 and 75% of such surgeries.[9]
[21]
[22] In our series, chondral lesions were found in 87.9% of the sample. Bhatia et al[19] observed a 28% prevalence of Outerbridge grade IV lesions in patients submitted
to hip arthroscopy; 78% of these lesions were isolated acetabular injuries, and independent
risk factors for their presence were joint space reduction and long duration of symptoms.
In our study, deep chondral lesions (grades III and IV of Haddad[18]) were found in 23.4% of the patients; however, these lesions did not indicate the
presence of a degenerative process (arthrosis), since chondral lesions classified
as deep resulted from chondrolabral junction rupture followed by the detachment of
the acetabular cartilage from the subchondral bone. Therefore, these lesions are delimited
and not related to a diffuse joint degenerative process. These chondral lesions are
candidates for arthroscopic treatment.[23]
The lesions grouped as deep in the present study can be classified as Outerbridge
grade IV due to subchondral bone exposure, as grade III due to macroscopic detachment
of cartilage from the subchondral bone, and as grade IV due to exposure of the acetabular
bone. In the present study, we did not find a statistically significant relationship
between alpha angle measurements and the presence of these lesions. This finding is
discordant from those of Bhatia et al,[19] who demonstrated that large alpha angles are related to Outerbridge grade IV chondral
lesions.
Claßen et al,[24] in a study with 177 patients submitted to hip arthroscopy for isolated CAM-type
impingement treatment, concluded that the NAHS analysis is also a predictive factor
of chondral lesions; however, this method was considered unreliable, with low sensitivity
and specificity (respectively, of 62.8 and 68.7%) when a cutoff value of 42.5 points
was used and the presence of chondral lesions was defined by the Outerbridge classification.
When the cutoff value is set to 30 NAHS points, the specificity is 100%, but the sensitivity
is 1%. Our analysis, which evaluated patients submitted to hip arthroscopy for the
treatment of mixed and CAM-type impingement, demonstrated an inverse relationship
of lesion severity with nonarthritic functional score, since patients with deep chondral
lesions had better preoperative functional scores. Surprisingly, this result suggests
that patients with better functional scores have worse joint injuries. Few studies
evaluate the conservative FAI treatment. Wall et al,[25] in a systematic literature review, concluded that physical therapy and lifestyle
modification may provide some benefit to the patient. Emara et al,[26] in a prospective analysis of a case series with 37 patients, showed improvement
of the mean NAHS values from 72 to 91 points after conservative treatment including
restriction of joint overload, use of anti-inflammatory agents, physical therapy,
and modification of activities predisposing to FAI; with an average follow-up period
of 25 to 28 months; this treatment resulted in 4 failures that required surgery. Since
there is a relation between the duration of symptoms and the incidence of chondral
lesions,[19]
[25] we suspect that patients with chronic pain can modify their lifestyle and reduce
hip overload activities to obtain a partial improvement in their functional score.
In the sample studied, there was no significant difference (p = 0.253) between age and deep lesions, although the mean age was slightly higher
in patients with deep chondral lesions. Men presented better functional scores and
also a higher prevalence of deep lesions, a finding compatible with previous studies.[1]
[4]
[13]
The main limitation of the present study was not to consider the time the patient
was exposed to the chondral lesion and the impossibility to estimate the impact that
the injury time has on the outcome (number of symptoms measured by the score). In
addition, the sample is composed mainly by patients with mixed FAI, and there are
indications in the literature that pincer impingement is a protective factor for chondral
delamination.[14]
Conclusion
In our sample, patients with deep hip chondral lesions presented significantly better
NAHS scores compared with patients with no chondral lesions or mild lesions. Hips
classified as Tonnis 1 were 4.4 times more likely to have deep chondral lesions compared
with those classified as Tonnis 0. Men undergoing FAI treatment had better preoperative
functional scores than women, and a higher prevalence of Haddad[18] grade III and IV lesions. There was no statistically significant association between
the presence of deep chondral lesions and alpha angle, lateral coverage angle, and
age.
