Superior Labral Tears of the Shoulder: Surgical Repair Using a Bioabsorbable Knotless Suture Anchor
Conrad Wang MD, Edward Yian MD, Peter J. Millett MD MSc, Jon JP Warner MD
HARVARD SHOULDER SERVICE, DEPARTMENTS OF ORTHOPAEDICS AT MASSACHUSETTS GENERAL HOSPITAL AND BRIGHAM AND WOMEN'S HOSPITAL, BOSTON MA
Abstract
The diagnosis and treatment of superior labrum (SLAP)
tears have improved with the development of arthroscopic
shoulder surgery techniques. With tears involving detachment
of the biceps anchor, the goal is to restore stability to the labrum
and biceps anchor and achieve healing to the glenoid. Suture
repair with anchors is currently the repair technique of choice.
The purpose of this article is to review the classification, pathoanatomy
and treatment of SLAP lesions, and to report a simple
method for arthroscopic SLAP repair that uses knotless suture
anchors and obviates the need for complex suture management
and arthroscopic knot tying. We also present preliminary clinical
results of isolated SLAP repairs in a general population.
Introduction
The rapid evolution of arthroscopic shoulder surgery over
the past decade has given orthopaedic surgeons the ability to
treat many injuries utilizing arthroscopic techniques, with
the goal of an anatomic repair. Andrews et al. first described
superior labrum lesions in 19851, and the acronym SLAP
lesions (superior labrum anterior to posterior) and their classification
was subsequently proposed by Snyder et al.2 and
further defined by Maffet et al.3 Snyder described four types
of lesions with increasing involvement of the biceps tendon2.
Type I lesions are characterized by fraying of the superior
labrum with an intact biceps anchor. Type II lesions represent
detachment of the biceps anchor and superior labrum. Type III
lesions are a bucket-handle tears of the superior labrum, with
an intact biceps anchor insertion to bone. Type IV lesions are
a bucket-handle tear of the superior labrum with extension into
the biceps tendon. For types II and II, the currently preferred
treatment is surgical repair to restore stability to the biceps
anchor. The true prevalence of SLAP lesions in shoulder injuries
remains unknown, but reported values have ranged from 6% to
26% of all patients undergoing shoulder arthroscopy4,5.
SLAP lesions can often be debilitating, especially in the
overhead athlete. Snyder et al. characterized his experience
with over 140 lesions and reported that only 28% of SLAP
lesions were an isolated entity2. More recently, Kim et al.
reported that only 12% of 139 patients with SLAP lesions did
not have associated pathology4. Associated lesions included
partial and full thickness rotator cuff tears, Bankart lesions
and acromioclavicular joint degenerative disease. However, the
relationship between SLAP lesions and associated pathology
has not yet been defined.
It has been suggested that the biceps and its attachment at
the supraglenoid tubercle plays a role in shoulder stability. In
experimental studies, the creation of a superior labrum lesion
decreased the ability of the shoulder joint to resist external
rotation when the shoulder was positioned in abduction and
external rotation6. Selective cutting studies have demonstrated
that release of both of the superior labrum and supraglenoid
tubercle are required to produce significant laxity of the biceps
tendon7. Electromyographic studies on activity of the long
head of biceps in shoulder function have been conflicting, as
Sakurai et al. have reported significant contraction of the long
head of biceps in repetitive maximal isometric forward flexion
and abduction8, but Yamaguchi et al. reported no activity in the
long head of biceps with shoulder motion9.
Several explanations of the mechanism for superior labral
injury have been suggested. Andrews et al. proposed that traction
of the long head of biceps tendon "pulls" off the attached
labrum1. Similarly, Maffet et al. proposed that traction injuries
were the most common mechanism with an inferiorly directed
force3. In contrast, Snyder et al. suggested that the most common
mode of injury was a compressive mechanism from a forward
fall, leading to a tear beginning posterior and extending
anterior to the biceps anchor2.
Patients with SLAP lesions involving the biceps anchor that
have persistent symptoms despite conservative management
are candidates for surgical repair. Suture repair with anchors is
widely advocated2,10. In experienced hands, arthroscopic knots
can provide secure fixation. However, there is a significant
learning curve associated with arthroscopic knot tying, and
improper knot tying with sliding knots may be a potential cause
of treatment failure and recurrent pain.
Bioabsorbable knotless suture anchors (BioKnotless
anchor, Mitek, Norwood, MA) have been reported to provide
a secure, low profile repair without the added complexities of
arthroscopic knot tying. The knotless anchor consists of a
polylactic acid body with two prongs and an attached, closed
"anchor" loop of braided Panacryl™ suture11. A longer, open
"utility" suture loop is threaded through the anchor loop and
is used to pass the anchor loop through the injured soft tissue,
by means of any of several suture passing devices. One
strand of the anchor loop is then captured between the two
prongs of the anchor and driven into the bone, thus pulling
the injured soft tissue into the drill hole with it. The utility loop
is then removed from the joint, leaving only the two arms of
the anchor loop securing the tissue to bone. Advantages of the
knotless anchor include a lower implant profile, a bioabsorbable
implant, increased suture strength (two suture limbs)
compared with simple sutures, and the potential for improved
healing as the tissue is pulled into the drill hole rather than on
top of the suture anchor. Benefits of the new technique also
include secure, reliable fixation, no need for bulky, difficult
knots, and a more efficient operation.
A multitude of arthroscopic repair techniques have been
described with associated portal placements, suture passage
devices and fixation equipment. O'Brien et al. have recently
reported good results using a lateral trans-rotator cuff portal
for suture anchor repair of SLAP lesions12. This article describes
the authors' preferred technique for the repair of unstable SLAP
lesions with a bioabsorbable knotless suture anchor utilizing an
accessory trans-rotator cuff lateral portal.
Operative Technique
Anesthesia and Patient Positioning:
Our preferred anesthetic is a long-acting regional interscalene
nerve block. This provides intra-operative and post-operative
analgesia, minimizes postoperative pain, and allows for fast-track recovery.
A careful examination under anesthesia is performed to
record passive range of motion and joint translation.
While repair of the superior labrum can be performed in
the lateral decubitus position, we prefer the beach-chair position.
This position allows easy access to the shoulder and facilitates
the exposure for an open repair if the need should arise
due to additional findings during arthroscopic evaluation. We
utilize a surgical positioner (T-MAX positioner, Tenet Medical
Engineering, Calgary, Canada) with a padded headrest in order
to ensure adequate exposure of the posterior and lateral borders
of the shoulder joint. It is important to keep the medial
border of the scapula exposed and without interference from
drapes. We have also had successfully utilized a set-up using
a long beanbag on a standard surgical chair13. A pneumatic
arm holder (The Spider, Tenet Medical Engineering, Calgary,
Canada) is used to facilitate intraoperative positioning of the
upper extremity.
Diagnostic Examination:
Bony landmarks are identified and marked including
the coracoid process, clavicle, acromioclavicular joint, acromion,
and scapular spine. For introduction of the cannulae, the
patient's arm is placed in slight traction, 50 degrees of forward
flexion and neutral rotation.
The skin is infiltrated with 0.25 % marcaine with epinephrine
solution at the portal sites. The posterior portal is located
2 cm inferior and 1 cm medial to the posterolateral tip of the
acromion (Figure 1). Saline solution is injected through the
soft spot into the glenohumeral joint with careful attention to
evaluate for back flow to prevent inadvertent infiltration of the
capsular tissues. A 30-degree arthroscope is placed into the
glenohumeral joint through the posterior portal to view the
glenohumeral joint. An anterior portal is made via the "outside-
in" approach with a spinal needle directed anterolateral to
the AC joint through the rotator interval and inferior to the
biceps tendon. A smooth, 5.5 mm x 70 mm cannula is inserted
through this portal.
A complete, systematic arthroscopic examination of the
glenohumeral joint is performed. Shoulder laxity is assessed
with the arthroscopic anterior drawer test and drive-through
sign. The quality of the capsular tissue and the degree of synovitis
are also assessed. A probe is used to evaluate the stability
of the labrum and biceps anchor. Recognition of the normal
anatomic variants of the anterior labrum (sublabral foramen,
Buford complex, or sulcus) is critical to unnecessary repair and
postoperative stiffness or restriction of motion. Specifically, it
is crucial to examine the undersurface of the labral attachment.
Signs of injury included excessive laxity, fraying, partial detachment,
tearing of insertional fibers, or elevation greater than 5
mm. The "normal" amount of laxity in the superior labrum
is unknown and is probably extremely variable. Identification
of labrum stability both anterior and posterior to the biceps
anchor is important for proper accessory portal placement.
Lesion Preparation
After identification and classification of the SLAP lesion, a
shaver is introduced through the anterior portal, and frayed or
unstable labral tissue is debrided. For type I and type III SLAP
lesions, no further treatment is indicated. Types II and type
IV SLAP lesions are repaired. The superior rim of the glenoid
is debrided free of soft tissue to expose a bony surface. At this
point an accessory lateral trans-rotator cuff portal is created,
1-2 centimeters lateral to the acromion.
Trans-Rotator Cuff Portal Placement
The arm is placed in maximal adduction in order to establish
the portal through the proximal portion of the rotator cuff,
away from its tendinous insertion. The optimum angle for the
portal is first determined with a spinal needle, with the goal of
directing the drill for the anchor at 45 degrees to the glenoid
rim. For posterior tears, passage of the spinal needle through
the supraspinatus or infraspinatus is necessary (Figure 2). A
#11 scalpel blade is passed in line with the muscular fibers
of the rotator cuff, under direct vision using the arthroscope
(Figure 3). An entry portal measuring 5 millimeters is established.
The arm may then be abducted for easier visualization
of the rotator cuff tendinous insertion. It is important to stay
as medial as possible, near the musculotendinous junction. A
switching stick is used to enlarge the entry and a 5.5-mm x 70-
mm smooth cannula is inserted over the rod.
Repair
A single 2.9-mm drill hole is made at the articular margin
of the superior glenoid rim. Marking the location of the drill
hole with radiofrequency cautery can simplify correct anchor
placement. A suture hook (Spectrum Tissue Repair System,
Linvatec Co., Largo, FL) is passed through the lateral portal
to deliver a wire suture passer (Shuttle Relay, Linvatec Co.,
Largo, FL) through the superior labrum from superior to
inferior, towards the glenoid. (Figure 4) The end of the suture
passer is retrieved through the anterior portal. The suture
hook is removed and the ends of the utility loop suture of the
bioknotless anchor are loaded into the suture passer (outside
of the lateral portal). Pulling the suture passer out through
then anterior portal thus passes the utility loop through the
superior labrum from superior to inferior. Alternatively, the
utility loop can be passed through the superior labrum using
a curved suture passer (Suture Lasso, Arthrex, Naples, FL). A
larger, threaded 8.0-mm cannula is placed anteriorly through
the rotator interval to accommodate the increased size of the
curved suture passer. The curved suture passer is introduced
through the anterior portal and passed through the superior
labrum from inferior to superior, adjacent to the predrilled hole.
An attached wire loop is then fed through the curved suture
passer and retrieved through the lateral portal with a suture
retriever. The free ends of the utility look suture are placed
through the wire loop. Removal of the curved suture passer
from the anterior portal then passes the utility loop through the
superior labrum from superior to inferior.
Anchor Passage
Tension is maintained across the utility loop suture ends as
the anchor is introduced into the joint from the lateral portal.
After the anchor loop is pulled through the labral tissue by the
utility loop, one strand of the anchor loop is captured under
the anchor prongs and the anchor is driven into the previously
marked drill hole until the loop is completely buried into bone
(Figure 5). The depth of anchor insertion modulates tension
of the repair, and one is able to visualize a "bumper" effect of
gathered superior labral tissue. The repair is then probed to
assess stability and the need for additional anchors (Figure 6).
In our experience, a single anchor placed just posterior to the
biceps anchor provides excellent stability of repair.
Clinical Results
SLAP lesions have been reported as a significant source of
shoulder pain in overhead athletes, but less is known about the
significance of isolated SLAP lesions in nonathletes. We have
therefore reviewed the results of arthroscopic stabilization of
isolated type II SLAP lesions in a general population.
Over a period of twenty months, 32 patients (25 male, 8
female) with isolated type II SLAP lesions were treated. Twenty
injuries were in dominant shoulders. Mechanisms of injury
were sports-related in five patients (weightlifting, tennis, diving,
volleyball); trauma-related in five patients (motor vehicle
collisions, falls from greater than standing height); due to falls
from standing height in seven patients; and from repetitive
injury or atraumatic in seven patients. Ten patients reported
work-related injuries.
Early follow-up suggests that repair of isolated type II SLAP
lesions is effective at returning patients to pre-injury work and
sport levels, with two-thirds of patients returning to work at
their previous level, and one-half of patients returning to sports
at their previous level. While the numbers are small, there is
also a suggestion that patients with work-related injuries may
not fare as well after isolated SLAP repair. The most common
complaint after surgery was persistent pain with overhead
activity.
Discussion
Knotless suture anchors can simplify the technique for
arthroscopic SLAP repair and lead to a shorter operative time.
However, potential pitfalls still exists, and are primarily technique-
related. They include:
- Damage or transection of the labrum or biceps as the tear is debrided or the suture passer is used.
- Iatrogenic damage of the articular surface from slippage of the drill tip off the glenoid rim or incorrect angle placement. This can be prevented by using a spinal needle to assess an optimal approach angle before portal placement, as well as by using a drill guide or tapping on the drill handle before drilling the anchor hole.
- Injury to the rotator cuff if the scalpel blade is inserted too laterally, or obliquely to the fibers of the rotator cuff.
- Bending or breakage of the suture hook tip if an incorrect angle results in application of excessive force during attempted suture passage (Figures 7,8).
- Suture abrasion and improper fixation arising from twisting of the suture loop during anchor insertion.
- Improper fixation from impacting both limbs (instead of one limb) of the anchor suture loop into the drilled hole.
- Failure of the tissue through the suture loop arising from over impaction of the knotless anchor into bone.
We have presented our technique for performing
arthroscopic superior labrum repair using a bioabsorbable
knotless suture anchor, which minimizes the need for complex
suture management and arthroscopic knot tying. It is easily
reproducible and appears to allow for a safe and stable repair.
With careful examination and documentation, arthroscopic
stabilization of symptomatic isolated superior labral detachment
in a general population produces good results according
to patient assessment of pain relief and shoulder function and
patient satisfaction. Poorer results may be influenced by patient
secondary gain. Further investigation of patient outcomes after
isolated SLAP repair is currently being performed, in order to
evaluate the longer-term efficacy of these repairs.
Acknowledgements
Figures 1-7 reprinted from Arthroscopy, Yian E et al.
"Technical Note: Arthroscopic Repair of SLAP Lesions with a
Bioknotless Suture Anchor," (In Press), with permission from
Elsevier.
Notes:
Conrad Wang, MD is a Resident in the Harvard Combined Orthopaedic Residency Program
Edward Yian, MD is a Fellow in Shoulder Surgery, Harvard Shoulder Service
Peter Millett, MD, MSc is a Clinical Instructor in Orthopedic Surgery, Harvard Medical School, and Attending Physician at Brigham and Women's Hospital
Jon J.P. Warner, MD is an Associate Professor of Orthopedic Surgery, Harvard Medical School, Attending Physician at Massachusetts General Hospital, and Chief of the Harvard Shoulder Service.
Please address reprint requests to: Peter J. Millett, MD, MSc 275 Cambridge Street, POB 403 Boston, MA. 02114 Telephone: 617-732-5793 Fax: 617-724-3846 Email: pmillett@partners.org
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