Keywords
Bankart lesions - glenoid cavity - shoulder dislocation
Introduction
The decision on the type of surgical treatment of recurrent anterior shoulder dislocation
has undergone recent changes.[1] The choice between anatomical surgery (Bankart repair) and non-anatomical surgery
(remplissage or Latarjet) depends on several clinical and imaging factors, with the
presence of bone loss of the glenoidal cavity or humerus head being highlighted as
one of the most important.[2]
[3]
[4]
[5] Depending on the percentage of bone loss of the glenoidal cavity, the risk of failure
of Bankart arthroscopic repair increases significantly.[6]
The glenoid track allows a combined evaluation of glenoidal cavity and Hill-Sachs[7] lesions, with them being characterized as on-track or off-track. [3] This concept was ratified by the finite element model,[8] and it is believed that this evaluation may predict lesions with a higher risk of
failure after arthroscopic repair of isolated Bankart.[3]
This concept has been widely used to assist in the choice of treatment, with several
biomechanical studies demonstrating its importance.[3]
[7]
[9]
[10]
[11]
[12]
[13] However, few studies have evaluated its clinical validity,[14]
[15] and only one study compared its results with the isolated evaluation of the glenoidal
cavity.[14] No previous study compared the results of the glenoid track with the threshold of
subcritical glenoidal cavity bone loss (13.5% in anteroposterior diameter).[16]
Our main objective was to evaluate the correlation of the glenoid track and subcritical
glenoidal bone loss with the recurrence rate of dislocation and the score on the Rowe
scale.
Material and Methods
The study was approved by the Ethics Committee for The Analysis of Research Projects
under opinion 1,269,108.
Study design
We conducted a retrospective analysis in a single center. The surgeries were performed
consecutively by four shoulder and elbow surgeons between January 2013 and February
2018.
The inclusion criteria were patients older than 14 years with one or more episodes
of anterior dislocation and who underwent primary arthroscopic repair of the Bankart
lesion with a minimum follow-up of 24 months, who had undergone preoperative magnetic
resonance imaging (MRI).
Patients with bone loss of the anteroposterior diameter of the glenoidal cavity greater
than 21%, concomitant partial or total rotator cuff tear, scapular waist fracture,
and posterior or multidirectional instability as well as those submitted to remplissage
procedures were excluded. Posterior and superior Bankart lesions on MRI were not considered
exclusion criteria.
Treatment
Arthroscopic Bankart repair was performed in the lateral decubitus. After confirming
Bankart's lesion, the glenoidal cavity edge was prepared, and glenoid labrum mobilization
was performed. Associated lesions of the upper or posterior glenoid labrum were also
prepared for repair with bioabsorbable suture anchors placed on glenoid edge. Then,
a repair of the labrum with absorbable anchor loaded with a high-strength wire was
performed.
The physiotherapy protocol consisted of 4 weeks with sling, performing active movements
of elbow, wrist and fingers 3 times a day. From the 4th postoperative week on, patients could perform passive and active movements assisted,
limiting external rotation to up to 30° until the 6th week. Muscle strengthening was performed only from the 8th week on.
Characteristics of the studied population and results
The primary outcome was the Rowe score[17] at 24 months, and the secondary outcome was the recurrence rate of dislocation.
The initial evaluation included age at first dislocation, age at time of surgery,
gender, involvement of the dominant limb, participation in sports, number of anchors
used in the anterior Bankart repair, and the need for posterior or superior labrum
repair.
Image analysis
Magnetic resonance images were obtained using the GE HDxt 1.5-T device (General Electric
Medical System, Walchesha, WI, USA) with dedicated shoulder coil. The patients were
in a supine position, with their arms next to the body in neutral rotation. T2-weighted
sequences were performed with fat suppression in the three orthogonal planes, coronal
sequence in proton density, and T1 sagittal sequence. Intra-articular or intravenous
gadolinium was not used in any of the exams. All measurements were performed by a
shoulder and elbow specialist with 14 years of experience only once and using the
iSite enterprise 4.1 image communication and archiving system (Philips Medical Systems,
Best, Netherlands).
The Hill-Sachs evaluation was performed in T2-weighted axial image with fat suppression.
Bone loss of the humerus head was measured in axial slice, from the linear distance
of the joint insertion of the rotator cuff to the medial margin of the Hill-Sachs
lesion.[14] Axial slice with the largest Hill-Sachs lesion was used to measure the Hill-Sachs
interval[14]
[18]
[19] ([Figure 1]). The evaluation of the glenoid was performed using a more lateral T1-weighted oblique
sagittal slice that included the glenoid. The perfect circle method ([Figure 2])[20]
[21] was used, providing the relative value of glenoid bone loss. The patients were divided
into 2 groups according to the threshold of “subcritical bone loss” (≤ 13.5% or > 13.5%
of the anteroposterior diameter of the glenoidal cavity).[16]
Fig. 1 Axial slice of magnetic resonance imaging for evaluation of the Hill-Sachs interval
(A).
Fig. 2 Measurement of the anterior defect of the glenoid was performed by the perfect circle
method in modified sagittal slice of the more lateral portion of glenoid on magnetic
resonance imaging. The diameter of the glenoid (D) and the bone defect (C); calculation
of the percentage of the anterior bone defect of the glenoid, using the formula: bone
defect of the glenoid (%) = C/D.
The glenoid track was calculated as 83% of the expected glenoid diameter, minus the
previous bone loss measured.[3] For on-track or off-track categorization, the glenoid track value was subtracted
from the Hill-Sachs range (absolute value of the glenoid track). If the Hill-Sachs
range were larger than the glenoid track, the injury was categorized as off-track.
Both the absolute value of the glenoid track and categorical descriptions were included
in the analysis.
Statistical analysis
Data normality was assessed by the Shapiro-Wilk test. Descriptive statistics, including
means and standard deviations, were used for variables with normal distribution, and
median and interquartile for non-normal distribution variables. The Fisher exact test
was used for categorical variables, and the Wilcoxon and Mann-Whitney tests were used
for non-normal distribution variables. The subgroup analysis was performed for the
glenoid track and for the bone loss of the subcritical glenoid respecting the quartiles,
division of the set into four equal parts of the sample distribution. All statistical
analyses were performed in SPSS Statistics for Windows, Version 21.0 (IBM Corp., Armonk,
NY, USA), and the level of statistical significance was 5%.
Results
A total of 118 patients with 24-month follow-up were evaluated. Preoperative MRI was
available for 102 patients (86.4%), who were included in the study. The mean age was
31.1 years at the time of surgery and 23.4 years at the time of the first dislocation.
There were 79 male patients (77.5%). No patient practiced professional sports. [Table 1] describes the baseline characteristics and the intervention used for each patient.
Table 1
|
Parameter
|
General (N = 102)
|
|
Age, years
|
31.1 (9.8)
|
|
Age at first dislocation, years
|
23.4 (8.2)
|
|
Male patients
|
79 (77.5)
|
|
Involvement of the dominant arm
|
56 (54.9)
|
|
Sports practitioners
|
34 (33.3)
|
|
Smokers
|
9 (8.8)
|
|
Number of previous dislocations
|
|
|
1
|
2 (2.0)
|
|
2–5
|
91 (89.2)
|
|
> 5
|
9 (8.8)
|
|
Glenoidal anchors number
|
2.8 (0.4)
|
|
Posterior labrum repair
|
6 (5.9)
|
|
Superior labrum repair
|
11 (10.8)
|
The mean score on the Rowe score in the preoperative period was 28.5 points (±11.2)
compared to 84.5 points (±18.8) in the 24-month follow-up, with a statistically significant
difference (p = 0.004).
Postoperative dislocation was reported by 8 patients (7.8%). Four patients underwent
open Latarjet procedure, and the other four were treated non-surgically.
The overall mean anterior glenoid bone loss was 9.7%. [Table 2] describes the evaluation of the bone loss of the glenoid, according to the two categorization
methods (glenoidal bone loss and glenoid track). [Table 3] describes the results of the Rowe scale scores for each of the two categories described
above.
Table 2
|
General (N = 102)
|
|
Average
|
SD
|
Median
|
IQR
|
|
Measurements of glenoidal bone loss
|
|
Glenoidal anterior defect, mm
|
2.6
|
1.7
|
2.7
|
2.1
|
|
Diameter of the glenoid, mm
|
26.7
|
2.9
|
26.4
|
3.0
|
|
Percentage of bone loss %
|
9.7
|
6.0
|
10.7
|
7.8
|
|
Glenoid track measurements
|
|
Hill-Sachs range, mm
|
15.3
|
4.7
|
14.7
|
5.6
|
|
Absolute glenoid track, mm
|
4.1
|
5.2
|
4.8
|
5.2
|
Table 3
|
|
ROWE score
|
P-value
|
|
N
|
Average
|
SD
|
Median
|
IQR
|
|
Glenoidal bone loss
|
|
≦ 13.5%
|
74
|
84.2
|
18.7
|
95.0
|
20.0
|
0.704
|
|
> 13.5%
|
28
|
85.0
|
19.6
|
92.5
|
25.0
|
|
|
Glenoid track
|
|
On track
|
86
|
84.9
|
18.6
|
95.0
|
25.0
|
0.566
|
|
Off track
|
16
|
81.9
|
20.5
|
85.0
|
19.0
|
|
In the analysis of subcritical glenoidal bone loss, the patients were divided into
two groups (≤ 13.5% or > 13.5%) ([Table 2]). Four patients (50%) in the recurrence group presented glenoidal bone loss greater
than 13.5% against 24 patients (25.5%) without recurrence, with no statistically significant
differences (p = 0.210).
The positive predictive value for a patient with glenoidal bone greater than 13.5%
with recurrence was 14.3%, and the negative predictive value was 94.6% ([Table 4]). The mean scores on the Rowe score were similar, with no statistically significant
difference (p = 0.704) in both groups of subcritical bone loss.
Table 4
|
Sensitivity
|
Specificity
|
Positive predictive value
|
Negative predictive value
|
|
Subcritical glenoidal bone loss
|
50 (15.7–84.3)
|
74.4 (64.4–82.9)
|
14.3 (7.1–26.6)
|
94.6 (89.7–97.3)
|
|
Glenoid track
|
37.5 (8.5–75.5)
|
86.2 (77.5–92.4)
|
18.8 (7.6–39.2)
|
94.2 (90.4–96.5)
|
In 16 patients (15.7%), the Hill Sachs' lesion was considered off-track. Regarding
the influence of Hill Sachs' lesion on the recurrence rate, we found 3 patients (37.5%)
in the group with recurrence with off-track lesion, compared to 13 patients (13.8%)
in the group without recurrence, with no statistically significant difference (p = 0.109).
Regarding treatment failure, 3 of the 16 off-track patients (18.7%) and 5 of the 86
on-track patients (5.8%) recurred. The positive predictive value for a patient with
an off-track lesion with recurrence was 18.8% and the negative predictive value was
94.2% ([Table 4]). The Rowe score was lower in the off-track group, with no statistically significant
difference (p = 0.566).
We performed a subgroup analysis, dividing the patients according to the quartiles
in relation to the absolute value of the glenoid track. We observed that patients
with absolute glenoid track value ≤ 1.5 mm had worse results in relation to dislocation
recurrence, with 6 patients (75%) presenting recurrence against 2 patients (25%) with
values above 1.5 mm (p = 0.003).
We did not relate the associated patients intrinsic factors (age at first dislocation
and number of dislocations) and lesions intrinsic factors (association with upper
posterior or anterior lesions and number of anchors in the repair of the lesion) with
the recurrence rate because it is not the objective of the study.
Discussion
As already pointed out by Momaya and Tokish,[10] the concept of glenoid track is an important tool for evaluating anterior shoulder
instability with bipolar injury, that is, glenoidal anterior bone loss (bone Bankart
injury) associated with posterior humeral head impactation fracture (Hill-sachs injury).
The concept helps in the best choice of treatment for each patient, either by arthroscopic
repair of isolated Bankart[22]
[23] or in association with the remplissage procedure[24]
[25] or using the Bristow-Latarjet bone block technique.[26]
[27]
[28]
Few studies have evaluated the influence of the concept of glenoid track on the risk
of recurrence and on clinical scores, performing its clinical validation. Shaha et
al.[14] evaluated 57 patients submitted to arthroscopic Bankart repair, and performed MRI
evaluation, similar to that used in our study. They observed high recurrence in patients
with off-track lesions (60%) against patients with on-track lesions (4%), with better
positive predictive values when compared to the isolated evaluation of the glenoidal
lesion. In a subanalysis of patients with bipolar lesions (30 cases), the authors
report even higher recurrence values in patients with off-track lesions (86%). Locher
et al.,[15] in a retrospective study with 100 patients, demonstrated that 33% of patients with
off-track lesions presented recurrence against 6% of those with on-track lesions.
The positive and negative predictive value are important indicators about the importance
of the glenoid track and subcritical bone injury in decision-making regarding surgical
treatment. The positive predictive value shows the probability of a case with off-track
injury or subcritical bone injury operated by arthroscopy presenting recurrence. The
negative predictive value, in turn, shows the probability of a case with on-track
injury or without subcritical bone injury operated by arthroscopy of not presenting
this complication. Thus, we were able to demonstrate high negative predictive values
for both subcritical glenoidal bone loss (> 13.5%) and for off-track lesions, with
values of 94.6% and 94.2%, respectively. Shaha et al.[14] and Locher et al.[15] also demonstrated similar findings for off-track lesions, with negative predictive
values of 92% and 94%, respectively. However, the authors did not evaluate the subcritical
glenoidal bone loss. Our findings, therefore, demonstrate that for patients with on-track
lesions and those with glenoidal bone loss lower than 13.5%, the risk of recurrence
with arthroscopic repair is low. Our Rowe score results were not statistically different
for off-track lesions and subcritical bone loss of the glenoid, in contrast to the
findings of Shaha et al.[14]
We can present some criticism over the glenoid track method. The results of the present
evaluation are categorical, on-track and off-track, which simplifies decision-making
between arthroscopic Bankart repair, associated or not with the remplissage procedure
and Latarjet surgery.[3] However, it does not value the wide variety of bone lesions, a fact that may hinder
decision-making in borderline situations, as it does not allow a direct evaluation
of the extent of bone lesions. It should be emphasized that other factors intrinsic
to the patient and the lesion, such as age at the time of the first dislocation and
at the time of surgical treatment; type of sport and sports level; and position and
extent of the Hill-Sachs lesion, have a relevant influence on the individualized evaluation
of each case for the decision to be made.
Shaha et al.[14] demonstrated that “almost off-track” lesions, that is, those with a difference between
the glenoid track and the Hill-Sachs interval (absolute glenoid track value) < 2 mm,
presented worse results on the Western Ontario Shoulder Instability (WOSI) score when
compared to “more on-track” lesions. We were able to demonstrate a great variability
of the absolute values of this difference, which presented an average of 4.1 mm (±5.2),
but with a variation of -11.5 to 22 mm. In a subgroup analysis of the absolute value
of glenoid track of less than 1.5 mm, we detected a greater difference between the
groups, including 6 (75%) of the patients with recurrent instability.
Another criticism is that the reliability of glenoid track measurements is not high,
mainly due to the difficulty of locating the insertion of the infraspinatus, either
on MRI or 3D computed tomography (CT), as originally described. Schneider et al.[29] demonstrated, by CT, that the coefficient of variability for the Hill-Sachs lesion
can reach 19.2%, compared with less than 4% for glenoidal bone loss. They also demonstrated
a low level of interobserver reliability in relation to on-track or off-track classification
(72%).
If we consider that measurement variations between 1.5 and 2 mm are common and that
they can alter the results of the categorization between on-track and off-track, and
the predictability of instability recurrence, as shown in our subgroup analysis, we
consider it essential to use the absolute glenoid track value in decision making,
especially in borderline cases. Just as the percentage of glenoidal bone loss is routinely
used, the use of the absolute value of the glenoid track could be described in studies
on the subject, as well as imaging reports.
Our study has some limitations. Magnetic resonance imaging (MRI) was used to measure
the glenoid track; however, there is no validation in the literature for the use of
such measure in this type of imaging examination, since it was developed for use in
CT; it is noteworthy that Bottoni et al.[30] in 2021 used MRI in the same way as us. The images were performed by only one orthopedist
in a single period. Although this standardizes the measurements, evaluated by a larger
number of evaluators and with a greater number of rounds of evaluations, obtaining
intra and interobserver agreement of the measurement of bone lesion measurements would
increase the reliability of the data obtained and, as demonstrated by Schneider et
al.,[29] the Hill-Sachs evaluation is probably less reliable than the evaluation of glenoidal
bone loss. In a future study, we intend to evaluate the agreement of bone lesion measurements
in an enlarged series. A larger sample of recurrence cases would be beneficial to
support external validity and to perform a multivariate regression analysis that included
other variables intrinsic to the patient, injury, and surgery in the search for prognostic
factors for arthroscopic treatment of anterior dislocation. The concept of subcritical
injury was presented by Shaha,[16] in 2015, in a military population; our sample included civilian patients, and only
33% of the patients were sport practitioners, a fact that may explain the discordant
results and decreased the sensitivity of imaging methods for detection of recurrence.
However, both populations are similar, mainly composed of young and male individuals.
Conclusion
Off-track Hill-Sachs lesion and glenoidal bone loss greater than subcritical (13.5%
of anteroposterior diameter) do not present significant clinical relationship with
recurrence rate and Rowe score, despite having high negative predictive value.
