Keywords
orthopedic procedures - shoulder instability - shoulder dislocation - arthroscopy
Introduction
Anterior instability is one of the most common orthopedic conditions in shoulder surgery,
with up to 23.9 cases per 100,000 people per year at the United States.[1]
Among the surgical techniques to treat this condition, one of the most effective and
well-established is the coracoid process and conjoined tendon transfer to the anterior
glenoid border.[2]
It is speculated that this procedure was performed by Bristow before 1929;[3] however, greater technical details were only reported in 1958 by Helfet,[4] who described in length the technique he had learned in 1939 from Bristow himself.
In 1954, Michel Latarjet[5] established the modern concepts of this surgery using a screw to fix the coracoid
process and the possible subscapularis opening. Patte et al[6] disseminated this technique in continental Europe in the 1980s using two 4.5-mm
screws for graft fixation in a vertical position.
The technique of coracoid process and conjoined tendon transfer to the anteroinferior
border of the glenoid cavity was modified many times, but all alterations respected
the basic principles of triple blockade: bone block by the coracoid process, increased
tension at the inferior portion of the subscapularis muscle, and direct block by the
conjoined tendon.[7] Several of these modifications were successful, but also had known complications,
including loss of lateral rotation, osteoarthritis, pain, musculocutaneous nerve damage
and pseudarthrosis.[8]
These complications resulted in many surgeons abandoning this procedure in favor of
labral reconstruction, especially with the technological evolution of arthroscopy.
Recently, the continuous evolution of minimally-invasive methods allowed this procedure
to be performed consistently by arthroscopy with arthroscopic Latarjet.[7] The intra-articular view allows the surgeon to better position the graft, minimizing
complications such as osteoarthritis and instability. Insertion under intra-articular
view also ensures the presence of the medullary cavity in contact areas, improving
osteointegration.[7]
[9]
[10]
However, this approach required new instruments with increased surgical costs.
In 2009, a new arthroscopic surgical technique that enabled the coracoid process and
conjoined tendon graft transfer through a minimally-invasive approach, with no costs
resulting from the use of new special materials, was published. In this technique,
the graft is inserted horizontally into the anterior border of the glenoid cavity
using common arthroscopy materials, a small malleolar screw and a washer, a technique
known as the Bristow procedure.[11]
The present study describes the outcomes of at least two years of follow-up of 43
patients submitted to the Bristow procedure to treat anterior shoulder instability.
Methods
From September 2007 to December 2016, 48 patients underwent surgical procedures for
anterior shoulder instability treatment using the arthroscopic Bristow technique with
horizontal graft. All procedures were performed by the same surgeon. This is a retrospective
study, and the preoperative evaluation is considered as the baseline.
The first three patients were not submitted to preoperative or postoperative score
determination with a follow-up period longer than two years; data from two other patients
were lost.
The remaining 43 patients met the following inclusion criteria, and were evaluated
in the present study.
Inclusion Criteria
The inclusion criteria were: patients over 18 years old; with fFollow-up period of
at least two years; with Bankart bone lesion with glenoid loss greater than 20% (assessed
by magnetic resonance imaging [MRI] or computed tomography [CT] according to the percentage
loss of circumference diameter of the lower glenoid cavity toward its largest axis
of bone loss); humeral avulsion of the glenohumeral ligament (HAGHL): failure of previous
arthroscopic Bankart surgery; instability severity index greater than 6; and competitive,
contact sport athletes with any bone loss.[12]
Exclusion Criteria
The exclusion criteria were: patients without baseline assessment data; patients whose
preoperative data were lost or who were followed up for less than two years after
surgery; those who did not agree with the evaluation; patients under 18 years old
or from vulnerable populations; and patients submitted to other previous surgeries,
except for arthroscopic Bankart procedures.
Scores and Measurements
The following scores and measurements were assessed:
Modified University of California at Los Angeles (UCLA) score: although initially
designed to assess shoulder arthroplasty outcomes, it was modified for use in other
orthopedic shoulder conditions.[13]
Simple shoulder test (SST): one of the most recognized tests in the functional evaluation
of the shoulder.
Rowe score: created only for postoperative evaluation, its results must be compared
with cutoff values of 75 and 90, indicating good and optimal results respectively.
Loss of lateral rotation with adducted arm: the baseline was determined at the preoperative
evaluation. Goniometry was performed manually; data were recorded at 5° intervals,
and differences were reported.
Elevation: losses greater than 10° were reported.
Evaluations
The patients were assessed at baseline by lateral rotation measurement and the UCLA
score. Two years or more after surgery, the patients were evaluated regarding lateral
rotation, elevation, UCLA, SST and Rowe values.
The postoperative evaluations included radiographic examinations in every patient.
Postoperative CT scans were restricted to those patients with suspected complications.
Statistical Analysis
The statistical analysis was performed using the Stata 15 (StataCorp., College Station,
TX, US) software for Mac.
Data were tested for normality and evaluated according to their statistical nature
using two-tailed curves and values of p < 0.05. Data were evaluated regarding intention-to-treat (ITT) whenever possible.[14] The interim sample size analysis was performed by verifying its statistical power.
The causes for patient withdrawal from the study were reported.
Surgical Technique
The patients are placed in the beach chair position under general anesthesia, and
a standardized four-portal surgical technique is used. These portals are a posterior
portal, an anterolateral portal, a portal just above the coracoid process, and an
anteromedial trans-subscapular portal; the placement of the last two portals is aided
by an intravenous catheter measuring 2.1 × 45 mm to ensure the best position ([Fig. 1]).[11]
Fig. 1 Portals: APC, portal above the coracoid process; AMTS, anteromedial trans-subscapular
portal; AL, anterolateral portal.
With the optics at the posterior portal, the subscapularis muscle tendon is open broadly
following fiber direction with a strong Kelly forceps, electrocautery, and shaver
through the anteromedial trans-scapular portal ([Fig. 2]). The rotator interval and the origin of the coracoacromial ligament at the superolateral
border of the coracoid process are removed with electrocautery and shaver. The glenoid
cavity is enlarged by inserting the shaver through the anterolateral portal. Then,
using the anteromedial trans-scapular portal, the drill passes through the open space
in the subscapularis tendon and touches the border of the anteroinferior glenoid cavity.
The optics is moved to the anterolateral portal for better viewing, and a hole is
made 5 to 6 mm medial to the anterior edge of the glenoid cavity.[15] The size of this hole is measured. The optics is removed from the intra-articular
space and placed at the anterior subdeltoid; then, the pectoralis minor tendon is
released by electrocauterization through the portal located above the coracoid process,
and the osteotomy of the coracoid process is performed with a microsaw and osteotomes.
The use of the Kocher forceps previously inserted into the conjoined tendon through
the anteromedial portal can facilitate its exteriorization ([Figs. 3] and [4]). The size of the 3.5 mm malleolar screw must be the sum of the glenoid cavity depth
and the measured graft size after exteriorization through the anteromedial portal.
A washer must always be used in this procedure.
Fig. 2 Arthroscopic image of the shoulder showing the opening of the subscapularis tendon.
A) subscapular B) humerus C) glenoid cavity.
Fig. 3 Image of the left shoulder with the coracoid process externalized with the aid of
a Kocher forceps.
Fig. 4 Screw passing through the externalized coracoid process graft.
Then, a #5 multifilament nylon suture or a #2 high-strength suture is placed between
the washer and the screw head to pull it against the key, preventing the screw from
coming off the key, and securing the graft in the glenoid cavity through the opening
made in the subscapularis tendon ([Figs. 5] and [6]). A Kocher forceps is inserted through the portal located above the coracoid process,
with a slight compression, to control graft rotation during fixation.
Fig. 5 Arthroscopic image of the shoulder showing the fixation in the anterior glenoid cavity;
the arthroscope is in the anterolateral portal.
Fig. 6 Arthroscopic image of the shoulder showing the final fixation of the coracoid process
graft in the anterior glenoid cavity; the arthroscope is in the posterior portal.
A) subscapular B) inserted coracoid process C) glenoid cavity.
If the graft has an articular step, the bone shaver can be used to even it.
Increasing screw torque does not necessarily mean that the graft is properly secured;
to test screw tightness, a probe must be used to verify whether the washer is loose
or secure.
Results
Out of 43 patients evaluated at baseline, 3 could not be assessed postoperatively.
With the baseline data, these patients were maintained in the sample, and their scores
were copied from the baseline to the two-year assessment (ITT) to avoid any bias that
might favor the procedure.
The evaluated group consisted of 42 men and 1 woman with a mean age of 32.88 years
(18–60 years); the left side was affected in 15 patients, whereas the right side was
affected in 28 patients. The median follow-up time was 76 months (range: 129-24 months).
The causes for these procedures were the following: 28 patients had Bankart bone lesions
with at least 20% of bone loss; 1 individual had HAGHL; 9 patients had a history of
previous failed Bankart procedures; and 5 patients presented an instability severity
index greater than 6.
The mean UCLA, Rowe, lateral rotation loss and TSO values for these 43 patients (ITT)
are summarized in [Table 1].
Table 1
|
Baseline (±standard deviation or cutoff values for good/excellent results)
|
> 2 years postsurgery (±standard deviation)
|
p-value
|
n
|
|
UCLA
|
25.56 ± 0.50
|
33.23 ± 0.44
|
< 0.0001
|
43
|
|
Rowe
|
75 (good results)
|
94.25 ± 1.52
|
< 0.0001
|
40
|
|
Rowe
|
90 (excellent results)
|
94.25 ± 1.52
|
0.0082
|
40
|
|
SST
|
————————
|
11.35 ± 0.21
|
—
|
40
|
|
Loss of lateral rotation
|
————————
|
10.37 ± 1.36
|
—
|
40
|
The data presented statistically consistent results.[16]
There were no elevation differences greater than 10° regarding the contralateral side,
except for 2 cases.
The medial rotation was not evaluated; however, 10 out of 40 patients had discomfort
and disability during the extremes of this movement (SST, question 11).
Intraoperative Complications (43 Patients)
There were two coracoid process fractures, including an incomplete lesion submitted
to coracoid process cerclage with #5 multifilament nylon and an arthroscopic Bristow
procedure. The other fracture was complete and multifragmented, so we opted for an
arthroscopic conjoined tendon tenodesis in the anterior portion of the trans-scapular
glenoid cavity, with excellent long-term functional outcome. This last patient was
one of the three who could not be evaluated postoperatively, since he was not submitted
to the procedure under study.
No paresis, paresthesia or nerve damage occurred in either case.
Postsurgical Complications (40 Patients)
There were three pseudarthroses without clinical repercussions.
An 8.84° screw twist occurred in the medial direction of the axial plane without clinical
repercussions, since the graft consolidated even after twisting.
There were four osteolyses, three without clinical repercussions and one requiring
screw removal. Osteoarthritis was present in three patients; in two of them, the condition
was moderate, and in one, it was deemed initial according to the classification by
Samilson and Prieto.[17] Two of these patients already had moderate osteoarthritis before the surgical procedure.
One patient had an infection with a potential hematogenous origin six months after
the procedure. Anterior impingement was observed in two patients, including one with
associated graft osteolysis, and both required synthesis material removal. There were
no subdislocations or de novo dislocations after the procedure.
Concomitant lesions were treated in four patients, including three superior labral
anterior and posterior (SLAP) lesions and one cuff injury.
In total, there were 12 complications, 8 of which had no clinical repercussions. Complications
with repercussions included infection six months after surgery with potential hematogenous
origin, a coracoid fracture requiring an intraoperatively procedural change, and two
patients with previous impingement who required synthesis material removal more than
six months after surgery. These four patients with complications presented good responses
to the instituted treatments, with clinical improvement, except for the patient with
infection, who presented the worst functional outcomes in this series.
The interim analysis of the sample size showed an adequate size considering a significance
level of 0.001, with 99% of statistical power.[18]
[19]
Discussion
Recent changes in coracoid process transfer procedures have been reported, enabling
its performance by arthroscopy.[7]
[9]
[10]
The advantages of the arthroscopic method include the following: better visualization
of the graft insertion site; possibility of correction of articular steps under visualization;
intra-articular visualization of the graft to ascertain its correct location; the
ability to test lateral rotation under articular visualization; possible concomitant
treatment of other injuries; reduced adhesions; and improved cosmesis.[1]
[7] The disadvantages are the increased costs related to arthroscopy, the lengthy learning
curve, and the need for specific training.[7]
Coracoid process fractures were the worst complication from this procedure (three
cases). Edwards and Walch[20] suggest a two-finger technique, in which the screw torque is performed with only
the thumb and the index finger, avoiding excessive screw torque over the graft. Washer
visualization and test, in which the probe is run over the washer to make sure it
is fixed, can also increase the safety of the procedure, as in some cases the increased
torque felt on the key may not be due to graft compression, but to the fixation in
the contralateral cortex. As for size, a 3.5-mm non-cannulated screw and washer appear
to be the most suitable option. The aforementioned precautions ended coracoid process
fractures in the present series. In cases of fracture in which cerclage is not possible
or feasible, the author suggests a conjoined tendon tenodesis in the anterior portion
of the glenoid cavity with anchors.
Cadaveric studies have not found significant biomechanical differences between conjoined
tendon tenodesis and coracoid process and conjoined tendon osteosynthesis, suggesting
that there is no need for bone block to achieve shoulder stability in surgical procedures.[21]
[22] It is reported that shoulder stability may be more closely linked to soft tissue
passive and active mechanisms that are difficult to measure.[23]
In fact, neither the Bristow nor the Latarjet procedures, as originally described,
have enough bone to produce the bone-blocking effect. In the Bristow procedure described
by Helfet, the coracoid process is sutured to the anterior portion of the glenoid,
whereas in the Latarjet procedure, the coracoid process is osteotomized before the
insertion of the pectoralis minor, completely preserving this muscle attachment, and
the graft is very small.[4]
[5]
Although the bone-blocking effect certainly added stability to the procedure in the
modern Bristow and Latarjet variations, this benefit may only be perceived in patients
with Hill-Sachs lesions in a region located at a distance from the cuff attachment
that is greater to or equal than the original diameter of the glenoid cavity minus
the bone loss times 0.83.[24]
The literature discusses the ideal screw diameter for coracoid transfers. Walsh and
Boileau use 4.5-mm screws[25]; Burkhart et al[26] and Di Giacomo et al[27] use 3.75-mm cannulated screws; and Lafosse et al[7] use 3.5-mm screws. All of these authors use vertically-oriented grafts. In the technique
presented in the present study, the screw diameter will depend on the physical characteristics
of the patient, but there is a clear preference for non-cannulated 3.5-mm screws with
washers.
Walsh and Boileau[25] do not recommend using washers because of the large size of the screws and the proximity
to the washer when the graft is left upright. In this procedure, which is performed
with a smaller screw, the use of a washer resulted in mechanical benefits, and it
is recommended for two reasons: for load distribution and because it is a test option
in case of doubt whether the screw tightness comes from the torque against the contralateral
cortex or actual graft compression.
In the arthroscopic Bristow procedure, graft osteolysis was only observed in three
cases, and none in the last 15 patients. Since osteolysis can be associated with compression
forces imposed on the graft, perhaps the two-finger fixation methods and the washer
testing have been instrumental in these outcomes.[27] However, there is a potential bias because postoperative evaluations were performed
by radiographs alone, leaving CT scans for cases in which possible complications were
suspected.
A case of impinged osteolysis required screw excision.[28]
Even with only 1 case of synthesis material removal, 11 out of 40 patients answered
“no” or “discomfort” to question 11 of the SST. As such, some impingement may be underestimated
by this series. The author accepts that there may be an impingement, with no or low
clinical repercussions, on 27.5% patients. Screw removal was required in 2 of the
11 patients with impingement. The impingement may be associated with the graft angle,
which must be perpendicular to the fracture line and preferably not greater than the
continuity angle of the glenoid cavity circumference. Direct and dynamic visualization
through the intra-articular space gives the surgeon a greater control for graft positioning,
avoiding articular steps. The author suggests that graft size and obliquity are determining
factors in both impingement and effective glenoid depth.[29]
In the present study, the reoperation rate was of 5%, which is similar to the one
previously reported for open procedures.[8]
Two patients already had osteoarthritis before the procedure, and only one case presented
new radiographic signs. This low rate of osteoarthritis may be associated with the
direct visualization that enables intraoperative corrections to prevent articular
steps.
The absence of an articular step reduces the load on the graft because there is no
mechanical stress point, resulting in no significant changes in the pressure over
the superior-posterior glenoid quadrant.[10] It has been shown that not only graft lateralization, but also its medialization,
are associated with postoperative complications. Medialization greater than 5 mm is
associated with higher recurrence rates of shoulder instability.[30] The better intra-articular evaluation of the arthroscopic fixation region may be
a positive factor to avoid this complication.
So far, since there are no recurrences of instability and the follow-up of quality
of life shows statistically significant results, it is possible to affirm the effectiveness
of the technique.
In the present study, three pseudarthroses were observed, but none had clinical repercussions,
which is consistent with the literature. The amount of pseudarthroses may be underestimated
because the follow-up was mostly performed with conventional radiographs, which can
make this diagnosis difficult.
The author suggests that the use of a single screw is sufficient to fix the coracoid
process. Hovelius et al[30] reported 11 de novo dislocations in 319 shoulders, that is, a 3% rate, after the
open Bristow procedure. Of these patients, 13% had pseudarthrosis; however, the fibrous
union was enough to prevent recurrences. De novo dislocations were more associated
with graft medialization than with pseudarthroses.[30]
The absence of de novo dislocations in the present study may be associated with a
better graft positioning, improving the contact of the scarified area of the anterior
glenoid cavity with the graft cancellous bone in horizontal position; however, the
sample is too small to suggest such conclusions. Low recurrence rates, close to 1%,
in more than 2,346 open surgical procedures, are cited in the literature; the results
of the present study suggest this same trend of good results for the arthroscopic
procedure.[31]
Lower de novo dislocation rates are not associated with the use of two screws in similar
techniques.[26]
[32]
The postsurgical alteration of the musculocutaneous nerve has not been observed, despite
its 0.7% incidence in the literature.[10] Even with no neurological impairment, the author suggests larger series in order
to draw any conclusions regarding the superiority of the neurological safety of the
procedure.
The procedure resulted in the same length of hospital stay as other similar arthroscopic
surgeries, with a significant economic advantage due to the exclusive use of basic
arthroscopy materials, a small fragment screw and a washer.
Conclusion
The arthroscopic Bristow procedure showed extremely significant effectiveness in the
treatment of anterior shoulder instability; however, it is not a complication-free
procedure, with a 9% complication rate in the present series.
