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Complications Observed Following Labral or Rotator Cuff Repair with Use of Poly-L-Lactic Acid Implants
L. Pearce McCarty, III, MD1; Daniel D. Buss, MD1; Milton W. Datta, MD2; Michael Q. Freehill, MD1; M. Russell Giveans, PhD1
1 Sports & Orthopaedic Specialists, 8100 West 78th Street, Edina, MN 55417
2 Hospital Pathology Associates, 2800 10th Avenue, Suite 2200, Minneapolis, MN 55407
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Investigation performed at Sports & Orthopaedic Specialists, Edina, Minnesota

This article was chosen to appear electronically on February 13, 2013, in advance of publication in a regularly scheduled issue.



Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

Copyright © 2013 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2013 Mar 20;95(6):507-511. doi: 10.2106/JBJS.L.00314
5 Recommendations (Recommend) | 3 Comments | Saved by 3 Users Save Case

Abstract

Background: 

A variety of complications associated with the use of poly-L-lactic acid (PLLA) implants, including anchor failure, osteolysis, glenohumeral synovitis, and chondrolysis, have been reported in patients in whom these implants were utilized for labral applications. We report on a large series of patients with complications observed following utilization of PLLA implants to treat either labral or rotator cuff pathology.

Methods: 

Patients who had undergone arthroscopic debridement to address pain and loss of shoulder motion following index labral or rotator cuff repair with PLLA implants were identified retrospectively with use of our research database. A total of forty-four patients in whom macroscopic anchor debris had been observed and/or biopsy samples had been obtained during the debridement were included in the study. Synovial biopsy samples taken at the time of the arthroscopic debridement were available for thirty-eight of the forty-four patients and were analyzed by a board-certified pathologist. Magnetic resonance imaging (MRI) scans acquired after the index procedure and data from the arthroscopic debridement were available for all patients.

Results: 

Macroscopic intra-articular anchor debris was observed in >50% of the cases. Giant cell reaction was observed in 84%; the presence of polarizing crystalline material, in 100%; papillary synovitis, in 79%; and arthroscopically documented Outerbridge grade-III or IV chondral damage, in 70%. A significant correlation (rho = 0.36, p = 0.018) was observed between the time elapsed since the index procedure and the degree of chondral damage. A recurrent rotator cuff tear that was larger than the tear documented at the index procedure was observed in all patients whose index procedure included a rotator cuff repair.

Conclusions: 

Clinically important gross, histologic, and MRI-visualized pathology was observed in a large cohort of patients in whom PLLA implants had been utilized to repair lesions of the labrum or rotator cuff.

Level of Evidence: 

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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    References

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    F. Alan Barber MD, Andres Felipe Cobaleda MD
    Posted on May 09, 2013
    Very few of the anchors reported were made from PLLA
    Plano Orthopedic Sports Medicine and Spine Center, Plano Texas

    This article reports a series of 44 shoulders reoperated on for complications following labral or rotator cuff repair.  The conclusion of the article was that “gross, histologic, and MRI-visualized pathology was observed in a large cohort of patients in whom PLLA implants” were used. We would like to point out that this is misleading.

    Most readers would conclude that the implants in question were suture anchors and that all were composed of poly-levo-lactic acid (PLLA). In fact, very few of the anchors reported were made from PLLA. The vast majority of the patients reported (39) had anchors composed of poly levo (70%) dextro (30%) lactic acid (PLDLA 70L/30D). PLLA is very different from its copolymers and stereoisomers, and referring to all these different biodegradable polymers simply as PLLA is an error.

    In a more scientifically rigorous study than the current one, Park et al. reviewed a nonconcurrent cohort of 348 consecutive surgically treated SLAP tears and found that 6.3% underwent subsequent revision surgery2. This revision rate was analyzed based upon the material of the suture anchors used. No patients with titanium (0 of 26), poly ether ether ketone (PEEK) (0 of 87), or PLLA (0 of 4) suture anchors required reoperation. Anchors composed of the more amorphous and more rapidly degrading PLLA stereoisomers (PLDLA 70L/30D and PLDLA 96L/4D) were another matter. Seven of 169 (4.1%) patients with anchors made from PLDLA 70L/30D (the composition of the Arthrex Bio-Fastak and Bio-SutureTak) required reoperation and 15 of 62 (24%) patients with anchors made from PLDLA 96L/4D (the composition of the Linvatec Bio Mini-Revo) required reoperation. Again, while the numbers are certainly low no patient with an anchor made from PLLA required reoperation.

    McCarty et al.  report three of their re-operated patients had implanted suture anchors composed of PLLA1. The likelihood that degradation of the PLLA was the cause of symptoms in these patients can be challenged. McCarty et al. make the unreferenced statement in their report that PLLA degrades “…between ten and thirty months...” and that the mean elapsed time from the index procedure to the debridement was 18.8 months. In fact PLLA takes much longer than 30 months to fully degrade.

    Published clinical evidence exists that PLLA implants are macroscopically intact without apparent inflammatory response at 30 months3. However, this is not the case for the stereoisomers and copolymers of PLLA. Markedly different clinical reabsorption patterns have been documented between pure PLLA and its stereoisomer and copolymers4. This mean 18.8 month time interval is consistent with the degradation pattern for implants of PDLLA and copolymers of PDLLA and PGA which completely degrade between 10 to 14 months post insertion4.

    In their discussion, McCarty et al. cite the articles by Athwal et al.5 and Boden et al.6 as cases in which pure PLLA suture anchors were associated with glenohumeral complications. These case reports dealt with the Bioknotless anchor which used the absorbable suture Panacryl. Panacryl suture has been associated with concerns about the development of an inflammatory process. Also confounding these case reports is the associated use of thermal treatment and, in the one case which used braided polyester suture, a loose anchor was found within the glenohumeral joint. It is consequently very speculative to make a connection between the PLLA of the Bioknotless anchor and the problems listed in these case reports.

    Dozens of different biodegradable polymers have been used for arthroscopic surgery implants and as surgeons we need to recognize that these polymers have different properties. All have a similar degradation process. This degradation process starts as the long polymer chains begin to break down and the crystalline nature of the implant becomes more amorphous7. This leads to implant fragmentation into smaller segments, which are phagocytosed primarily by macrophages and polymorphonuclear leucocytes. The final degradation product for PLLA is the lactic acid monomer which enters the Krebs cycle and is released as carbon dioxide and water. There is an inherent inflammatory process in any degradation. The greater the rate of this inflammation the more clinically significant it can be. In the case of PLLA, this rate is measured in years and is very unlikely to create a clinically significant response. However, combinations of PDLLA reabsorb faster and the inflammatory response is greater.

    Macroscopic anchor debris are reported by McCarty et al. in over 50% of the cases after arthroscopic evaluations and polarizing crystalline material reported in 100%. The microscopic finding of monomer fragments in the tissue is not unexpected, but rather part of the normal degradation process.

    In summary, it is misleading to state that these anchors are composed of PLLA. These anchors were made from copolymers which entirely different material properties and degradation behavior. The degradation process of biodegradable polymers results in the long polymer chains breaking down to monomers as the degradation progresses so finding It is common to find polarizing crystalline material in biopsy material. Finally, PLLA takes much longer than 30 months to completely degrade.

    REFERENCES
    1.         McCarty LP, 3rd, Buss DD, Datta MW, et al. Complications observed following labral or rotator cuff repair with use of poly-L-lactic acid implants. J Bone Joint Surg Am 2013;95:507-511.
    2.         Park MJ, Hsu JE, Harper C, et al. Poly-L/D-lactic acid anchors are associated with reoperation and failure of SLAP repairs. Arthroscopy 2011;27:1335-1340.
    3.         Martinek V, Seil R, Lattermann C, et al. The fate of the poly-L-lactic acid interference screw after anterior cruciate ligament reconstruction. Arthroscopy 2001;17:73-76.
    4.         Stahelin AC, Weiler A, Rufenacht H, et al. Clinical degradation and biocompatibility of different bioabsorbable interference screws: a report of six cases. Arthroscopy 1997;13:238-244.
    5.         Athwal GS, Shridharani SM, O'Driscoll SW. Osteolysis and arthropathy of the shoulder after use of bioabsorbable knotless suture anchors. A report of four cases. J Bone Joint Surg Am 2006;88:1840-1845.
    6.         Boden RA, Burgess E, Enion D, et al. Use of bioabsorbable knotless suture anchors and associated accelerated shoulder arthropathy: report of 3 cases. Am J Sports Med 2009;37:1429-1433.
    7.         Athanasiou KA, Agrawal CM, Barber FA, et al. Orthopaedic applications for PLA-PGA biodegradable polymers. Arthroscopy 1998;14:726-737.

    Stephen Burkhart, MD
    Posted on April 23, 2013
    Complications observed following labral or rotator cuff repair with use of poly-L-lactic acid implants
    The San Antonio Orthopaedic Group, San Antonio, TX

    The authors described a mixed cohort of 44 patients who had undergone labral or rotator cuff repair by a total of 41 different surgeons. The only common thread in this cohort is that each patient developed postoperative pain and stiffness and that each patient’s repair had involved PLLA suture anchors. The authors make the rather breathtaking leap of concluding that the PLLA material was responsible for the pain and stiffness.

    I take issue with the authors’ conclusions for the following reasons:

    1. First of all, the vast majority of suture anchors used in the United States today are composed of a formulation of PLLA polymer. Therefore, any cohort of patients, either with excellent results or poor results will have received mostly PLLA anchors. So, using the authors’ line of reasoning, one could just as easily say that the excellent postoperative results in a given cohort were due to the PLLA anchors, since they were used in most of the patients with excellent results

    .2. The authors suggest that there is a similarity in the synovial response to degradation of PLLA anchors compared to the synovial response of PGA anchors, in which severe inflammatory reactions have been previously reported (2). However, the degradation profiles of PLLA and PGA are totally different (3,4). PGA has a rapid degradation profile during the first 4 weeks, releasing high concentration of acidic breakdown products that can incite inflammation. In contrast, PLLA has a reported degradation time between 10 and 30 months, and inflammation due to this low load of polymer degradation has not been confirmed in clinical studies or in animal studies.

    3. The authors suggest that the MRI findings of high signal and fluid around the anchors is pathologic. However, this is incorrect, Fluid signal around a biodegradable anchor occurs normally, since PLLA anchors degrade by hydrolysis to lactic acid and water. So the presence of fluid (water) around an anchor undergoing degradation is normal and is commonly observed.

    4. The authors’ assertion that 100% of biopsy specimens showed crystalline breakdown products of PLLA is not surprising, as all PLLA anchors degrade (they are supposed to do that), and I suspect that if we did synovial biopsies on post-op patients with PLLA anchors who healed uneventfully, they would all have some microscopic breakdown products because, as these authors correctly state on page 508, these polymers degrade by “hydrolytic dissolution with eventual phagocytosis by local macrophages.” I am not surprised to find breakdown products in the synovium, since PLLA is supposed to break down and be eliminated by cellular mechanisms in the bone and in the synovium.

    5. The authors’ dismissal of possible infection as an etiology is not logical. Many P. acnes infections can develop exactly as described in this report and may have negative cultures.

    6. The authors describe chondral damage that is worse in the vicinity of the labral anchors. This suggests the possibility of mechanical trauma at the time of surgery, the possibility of “proud anchors”, as well as possible abrasion from the heads of some of the headed-type implants (e.g. labral nails) that were used. Since these 44 patients underwent surgery by 41 different surgeons and did not constitute a cohort operated on by the authors, one cannot know how much of the chondral damage was mechanical at the time of the initial surgery. One cannot automatically conclude, as the authors did, that the chondral damage was a result of biochemical interaction with PLLA breakdown products.

     7. One cannot know how large a patient pool this cohort came from, so we cannot calculate the incidence of this association, even if one could establish that the authors have discovered a pain/stiffness syndrome related to the anchors (which the authors have not established).

    My biggest concern with this study is that the authors assert an association between post-op stiffness and crystalline-induced synovitis, when they have not proven such an association.  Specifically, all patients that develop post-op stiffness after arthroscopic repair have a synovitis that has the arthroscopic appearance of adhesive capsulitis, and in my personal series of 489 patients with PLLA-anchor cuff repairs with a conservative rehabilitation protocol, there was an incidence of post-op stiffness of 4.9% of patients who later required an arthroscopic release (5).  We identified categories “at risk” for developing post-op stiffness (single tendon repairs, combined labral and cuff repairs, PASTA repairs).  In these patients, we performed arthroscopic capsular release, without synovectomy, and they uniformly regained virtually full range of motion and obtained excellent durable pain relief.  This dramatic response to arthroscopic capsular release indicates that the synovitis was not due to an ongoing reaction to degradation products of PLLA because, if it were, the pain and stiffness should have recurred due to the continued degradation and the continued presence of breakdown products in the synovium (since synovectomy was not performed).  However, we did not observe recurrent stiffness after capsular release.  Furthermore, based on our experience with stiffness following our conservative rehabilitation protocol, we developed a customized rehabilitation protocol with early closed-chain stretches for “at risk” groups, and with this protocol we observed that post-op stiffness was virtually eliminated (6).  If crystalline-induced synovitis had been a factor in stiffness, we would not have been able to eliminate it in this group of patients, all of whom had cuff repair performed with PLLA anchors.

    I think that McCarty et al. are simply describing a mixed group of patients with postoperative stiffness and pain (from multiple etiologies, including well-known “at-risk” groups) and incorrectly assigning an etiology of synovitis secondary to PLLA degradation products.  In my shoulder-only practice, I have personally implanted over 10,000 PLLA (both PLLA and PLLA/β-TCP BioComposite) suture anchors, and have observed only the occasional post-op stiff shoulder (in patients from “at-risk” groups).  These patients have always responded to standard measures including physical therapy and/or arthroscopic capsular release, and they have not exhibited any chondral damage.  I believe that McCarty et al. have incorrectly assigned a cause-and-effect role to the anchor by-products, when such a role does not exist.

    In years past, I have observed many cases of chondral damage from metal anchors that were loose or proud, and in my experience the PLLA anchors are the safest anchors available to surgeons and their patients. I think that erroneous conclusions that contradict their long record of safety and reliability must be examined, exposed, and debated.

    REFERENCES

    1. McCarty PL III, Buss DD, Datta MW et al. Complications observed following labral or rotator cuff repair with use of poly-L-lactic acid implants. I Bone Joint Surg Am 2013;95:507-511.
    2. Edwards DJ, Hoy G, Saies AD, Hayes MG.  Adverse reactions to an absorbable shoulder fixation device.  J Shoulder Elbow Surg 1994;3(4):230-233.
    3. Dhawan A, Ghodadra N, Karas V, Salata M, Cole BJ.  Complications of bioabsorbable suture anchors in the shoulder.  Am J Sports Med 2012;40(6):1424-1430.
    4. Athanasiou KA, Agrawal LM, Barber FA, Burkhart SS.  Orthopedic applications for PLA-PGA biodegradable polymers. Arthroscopy 1998;14(7):726-737.
    5. Hubery DP, Schoolfield JD, Brady PC, Vadala AP, Arrigoni P, Burkhart SS.  Incidence and treatment of postoperative stiffness following arthroscopic rotator cuff repair.  Arthroscopy 2009;25(8):880-890.
    6. Koo SS, Parsley BK, Burkhart SS., Schoolfield JD.  Reduction of postoperative stiffness after arthroscopic rotator cuff repair: Results of a customized physical therapy regimen based on risk factors for stiffness.  Arthroscopy 2011;27(2):155-160.

    L.P. McCarty III, D. Buss, M. W. Datta*, M.Q. Freehill and M.R. Giveans
    Posted on April 22, 2013
    Reply to Dr. Busfield's Comment
    Sports and Orthopaedic Specialists; *Hospital Pathology Associates

    We appreciate Dr. Busfield’s interest in our study and acknowledge that his questions raise some relevant topics for discussion regarding our recent study. Regarding the question of culture retention, all cultures were maintained for a period of three weeks in order to rule out, in particular, Propionibacterium acnes as a potential source of occult infection. Furthermore, although absence of acute inflammatory cells on histological examination of pathology specimens does not de facto rule out the presence of an infectious agent, it does make the presence of such an agent less likely.

    None of the index procedures in this series were performed by either the lead or the senior author. All cases were referred from outside institutions. Dr. Busfield’s assertion that the authors are therefore limited by the presumed accuracy of outside medical documentation is correct, but such is an inherent limitation of any study with a retrospective component.

    Only one of the patients in the present study had undergone prior thermal capsulorrhaphy, which had been performed six years prior to the procedure involving implantation of PLLA anchors. Evaluation of this patient’s MRI prior to the PLLA-based procedure did not show any evidence of cartilaginous pathology. We therefore concluded in this case that the thermal capsulorrhaphy was not a factor, based upon the assumption that any thermal-induced chondrolysis would have manifested during the six-year interval between the two procedures.

    Regarding intaarticular pain pumps, seven out of the 44 patients potentially had such pumps placed. We state “likely” because the medical record did not indicate the precise anatomic location of pump placement. It is also unclear whether these pumps were of the bolus or continuous infusion type. We acknowledge the concerns expressed by Dr. Busfield regarding the use of such devices, particularly those utilizing a continuous infusion, placed within the glenohumeral joint.

    Once again, we appreciate Dr. Busfield’s interest in our work, and look forward to further research in this area.

    Benjamin T. Busfield M.D.
    Posted on March 21, 2013
    PLLA Implant Complications: Are there other risk factors?
    East Bay Physicians Medical Group, Antioch, CA, USA

    I read this article with great interest. Having seen these issues in the tibia with ACL bioabsorbable interference screws, I was curious about the types of complications found in this retrospective cohort.

    Although the 100% rate of finding polarizing macroscopic material from this cohort logically implicates a synovitis induced by the breakdown products of the PLLA implants as a cause of cartilage damage, I wondered about other potential contributing factors. Although one of the four inclusion criteria for the study specified that all patients had negative cultures, were these 5 day or 14 day cultures?

    In the discussion section, the authors stated that the small percentage of patients with acute inflammation would make occult infection such as P. acnes unlikely. With the mean delay to surgery of just over 18 months, lack of acute inflammation may not be a reliable indicator of infection.

    Furthermore, it is unclear what percentage of these patients had the index procedure done by the senior author. This is pertinent as the only way to determine if other risk factors for cartilage injury were present from the index procedure for referred patients would be by review of outside records. The quality of records for review would potentially be less complete than those patients who had surgery with the senior author.

    This study focused on findings from the debridement surgeries performed by the senior author's database. Did any of the patients have intra-articular pain pumps with local anesthetics or thermal capsulorrhaphy during the index arthroscopic surgery?

    I applaud the authors for this investigation. Certainly the 70% prevalence of Outerbridge grade III and IV cartilage damage is concerning after use of PLLA implants. I think further disclosure of known risk factors for cartilage damage from the index surgeries would only strengthen the findings in this study.

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