AJR 2003; 180:377-380
© American Roentgen Ray Society
MR Imaging of Complications of Loose Surgical Tacks in the Shoulder
Nancy M. Major1 and
Matthew C. Banks
1 Both authors: Department of Radiology, Duke University Medical Center, Box
3808, Durham, NC 27710.
Received June 27, 2002;
accepted after revision August 2, 2002.
Address correspondence to N. M. Major.
Abstract
OBJECTIVE. Loose surgical tacks in the shoulder joint are a
potential cause of new-onset shoulder pain after arthroscopic repair of an
anterior-to-posterior lesion of the superior labrum. We report the MR imaging
appearance of loose surgical tacks in this anatomic location.
CONCLUSION. MR imaging is valuable in the evaluation of
postoperative shoulder pain. Synovitis is a commonly considered clinical
diagnosis; our report illustrates that loose tacks are another potential
complication after shoulder surgery
Introduction
Tacks are widely used as fixation devices in the repair of a torn glenoid
labrum or rotator cuff and are important components of both open and
arthroscopic shoulder surgery, especially because many such tacks are
biodegradable. The tacks are made of polyglycolic acid, and a potential
postoperative complication with devices made from this compound is synovitis.
Loosening of surgical tacks is not typically suspected as a complication of
shoulder surgery. Because polyglycolic acid tacks are not visualized on
radiographs, diagnosis of the failure or loosening of the tacks is impossible
to make using radiography.
Subjects and Methods
Our study was a prospective evaluation of three men—18, 19, and 45
years old—whose surgeries had been performed by two different surgeons
and whose shoulder pain began within 2 months after the arthroscopic repair of
an anterior-to-posterior tear of the superior labrum. Before undergoing
postoperative MR imaging, all the patients had received a diagnosis of
postoperative synovitis with possible re-tearing of superior labrum.
All three patients were imaged on a 1.5-T magnet (Signa; General Electric
Medical Systems, Milwaukee, WI). We used a routine MR imaging protocol for the
shoulder, including oblique coronal and oblique sagittal images obtained with
a T1-weighted spin-echo sequence (TR/TE, 600/13) and T2-weighted fast
spin-echo sequence (TR/TEeff, 3500/65) with fat suppression. Axial
images were obtained with fast spin-echo proton density—weighted
(TR/TEeff, 3500/17) and T2-weighted fast spin-echo
(TR/TEeff, 3500/65) sequences. All images were fat-suppressed. Two
patients received 15 mL of intraarticular gadolinium (dilution ratio, 1:200)
and underwent arthrography. The field of view was 14 cm with a matrix of 256
x 192 and 2 excitations. The MR images were interpreted by two
radiologists.
Results
MR imaging nicely depicted the loose tacks floating freely in the joint
fluid in all patients, and the tract path in the glenoid where the tacks
originally had been placed was readily identifiable. A total of seven loose
tacks were found in the three patients (Figs.
1A,1B,1C,2A,2B,3A,3B,3C).
Neither the original anchoring site nor the tacks could have been identified
on radiography (the tacks are not radiopaque). Obviously, the findings on MR
imaging dramatically altered the patients' postoperative course. To prevent
damage to the articular cartilage, all three underwent a second procedure to
remove the tacks. If the patients had been judged to have only synovitis, they
would have received conservative treatment until the synovitis resolved.
View larger version (148K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A. —18-year-old man with shoulder pain 2 months after repair of
superior labral tear. Axial T2-weighted MR image derived from
gadolinium-enhanced arthrogram shows original anchoring site (arrow)
at level of superior aspect of glenoid. High signal in adjacent soft tissues
is result of gadolinium-enhanced arthrography.
|
|
View larger version (138K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B. —18-year-old man with shoulder pain 2 months after repair of
superior labral tear. Coronal T2-weighted MR image derived from
gadolinium-enhanced arthrogram obtained anteriorly from that of A at
level of subscapularis muscle and tendon shows obliquely oriented tack
(arrow) adjacent to subscapularis tendon.
|
|
View larger version (146K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C. —18-year-old man with shoulder pain 2 months after repair of
superior labral tear. Coronal T2-weighted MR image derived from
gadolinium-enhanced arthrogram shows another loose tack (arrow) more
vertically oriented and adjacent to humeral head articulation at glenoid.
|
|
View larger version (153K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A. —19-year-old man with shoulder pain 2 months after repair of
superior labral tear. Sagittal T2-weighted MR image shows tracts of displaced
surgical tacks (arrows) at superior aspect of glenoid.
|
|
View larger version (131K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B. —45-year-old man with shoulder pain 9 months after repair of
superior labral tear. Sagittal T1-weighted MR image shows original anchoring
site (arrow) of tack at superior aspect of glenoid.
|
|
Discussion
Using biodegradable materials is a common practice in orthopedics. In
particular, the use of bioabsorbable tacks has played a role in the repair of
rotator cuff tears and superior labral tears with anterior-to-posterior
orientations. Our study focused on the use of bioabsorbable tacks and the
repair of anterior-to-posterior lesions of the superior labrum. The number of
tacks placed at surgery for this repair varies but usually ranges from three
to five tacks, depending on the severity of the tear. Of course, bioabsorbable
tacks must be made of nontoxic substances, but the tacks must also have
adequate fixation strength to attach soft tissues to bone as well as
sufficient strength to allow the healing tissues to regain mechanical
integrity and a slow absorption rate so that breakage and migration of the
tacks are avoided. For proper healing to occur, a tack must be encapsulated by
the synovium or other tissue; therefore, one possible explanation for tack
loosening is that the tack loses its peripheral mass and separates from the
repaired tissue that it is meant to secure. The fixation strength of the tack
must be maintained until the process of capsulolabral healing is complete.
The normal sequence of biodegradation of the tacks involves five stages. In
the first stage, water is absorbed into the tack from the surrounding
environment. In the second stage, the polymer in the tack undergoes
hydrolysis, which results in decreased holding strength. During absorption
(the third stage), the tack begins to fragment, and its fixation decreases.
Tissue healing must have occurred by this stage. Then, the fragments of the
implant are phagocytized. Finally, the products of phagocytosis enter the
Krebs cycle and are eliminated through respiration. This entire process of
biodegradation can take from 5 months to 2 years
[1]. The most commonly reported
complication associated with biodegradable tacks has been synovitis
[2,
3], which was the clinical
concern for the patients in our series.
Many surgeons who arthroscopically repair anterior-to-posterior lesions of
the superior labrum using bioabsorbable tacks exclusively have reported good
success
[4,5,6].
To repair anterior-to-posterior tears of the superior labrum, surgeons
typically use an anterosuperior portal. However, if the tear extends too far
posteriorly to be stabilized only from the front, a posterosuperior portal is
also used. The posterosuperior tack can be difficult to place correctly during
the arthroscopic stabilization procedure
[7], so a potential
complication is that the tack can loosen to the point that it disengages and
floats freely in the joint space.
The reason that the absorbable tacks in our patients became loose remains
unclear. It could be that the posterior portal placement resulted in an
unsatisfactory positioning of the tacks. Another possible explanation is the
tacks began to lose mass before the surrounding tissue was healed, releasing
the tacks from the tissue. The infrequency with which cases of loose surgical
tacks are encountered may be related to the fact that many orthopedic surgeons
are using tacks less frequently in the repair of anterior-to-posterior lesions
of the superior labrum in favor of the technically more demanding suture
anchor repair. This procedure requires making a knot and placing it at the
capsulolabral interface or the tear site. The suture anchor does not have the
same tendency to back out of a tract that the bioabsorbable tack does
[8].
To our knowledge, failure of biodegradable fixation in repairs of
anterior-to-posterior tear lesions of the superior labrum has not previously
been reported in the literature, and our experience suggests that it is a rare
complication of shoulder surgery. Results of our study show that MR imaging
continues to prove useful in the evaluation of pain in the patients who have
undergone shoulder surgery. MR imaging allows one to distinguish between loose
tacks and synovitis in patients with postoperative shoulder pain, which is
important for the correct management of this complication.
Acknowledgments
We thank James B. Vogler III for his contribution to this article.
References
- Berg EE, Oglesby JW. Loosening of a biodegradable shoulder staple.
J Shoulder Elbow Surg
1996;5:76
-78[Medline]
- Bostman OM. Absorbable implants for fixation of fractures.
J Bone Joint Surg Am
1991;73A:148
-153[Free Full Text]
- Edwards DS, Hoy G, Saies AD, Hayes MG. Adverse reactions to an
absorbable shoulder fixation device. J Shoulder Elbow
Surg 1994;3:230
-233
- Pagnani MS, Spark P, Altchek DW, Warren RF, Dines DM. Arthroscopic
fixation of superior labral lesions using a biodegradable implant: a
preliminary report. Arthroscopy
1995;11:194
-198[Medline]
- Samani JE, Marsten SB, Buss DD. Arthroscopic stabilization of type
II SLAP lesions using an absorbable tack. Arthroscopy
2001;17:19
-24[Medline]
- Speer KP, Warren RF. Arthroscopic shoulder stabilization: a role
for biodegradable materials. Clin Orthop
1993;291:67
-74
- Trusler ML, Bryan WJ, Ilahi OA. Anatomic and radiographic analysis
of arthroscopic tack placement into the superior glenoid.
Arthroscopy
2002;18:366
-371[Medline]
- Kim SH, Ha KI, Kim SH, Choi HJ. Results of arthroscopic treatment
of superior labral lesions. J Bone Joint Surg Am
2002;84A:981
-985[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
T. Magee, M. Shapiro, G. Hewell, and D. Williams
Complications of Rotator Cuff Surgery in Which Bioabsorbable Anchors Are Used
Am. J. Roentgenol.,
November 1, 2003;
181(5):
1227 - 1231.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
