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Delayed degradation of bioabsorbable meniscal fixators
Case Report
Delayed Degradation of Bioabsorbable Meniscal Fixators William F. Sims, M.D., and Peter T. Simonian, M.D.
Abstract: A greater understanding of the functional importance of the meniscus has prompted a more aggressive approach to conserving meniscal tissue. Multiple treatment options exist when dealing with a tear of the meniscus. As the popularity of bioabsorbable implants in the orthopaedic armamentarium grows, concern exists as to the potential associated complications. We describe a case of the failure of a bioabsorbable meniscal fixator appropriately applied to a posterior medial meniscal tear with an associated injury of the anterior cruciate ligament. Moreover, the concern of implant retention secondary to delayed degradation and resultant potential for articular cartilage damage was present. Key Words: Meniscus—Tear—Bioabsorbable—Fixator—Degradation—Implants
M
eniscal repair has been shown to be beneficial and safe.1-3 The use of bioabsorbable meniscal fixation has become increasingly popular. Since gaining approval of the Food and Drug Administration in 1997, the use of polylactic acid (PLA) meniscal implants have been believed to provide a safe and simplified all-inside technique of meniscal repair, with limited reported complications.4-9 Recently, the concern of abrasion and furrowing of articular cartilage by retained PLA meniscal implants has been reported.10 We present the case of a 23-year-old woman who had undergone an anterior cruciate ligament (ACL) reconstruction and repair of a longitudinal, posterior horn, medial meniscus tear that was stabilized with PLA Clearfix meniscal screws (Innovasive Devices, Marlborough, MA). Seventeen months after the index procedure, the patient presented with a complaint of
From the Department of Orthopaedic Surgery and Sports Medicine, The University of Washington, Seattle, Washington, U.S.A. Address correspondence and reprint requests to Peter T. Simonian, M.D., Department of Orthopaedic Surgery and Sports Medicine, The University of Washington, Box 356500, Seattle, WA 98195, U.S.A. E-mail: [email protected] © 2001 by the Arthroscopy Association of North America 1526-3231/01/1703-2772$35.00/0 doi:10.1053/jars.2001.20668
mechanical symptoms that, on examination, were found to be localized to the posterior medial compartment of the patient’s knee.
CASE REPORT An athletic 23-year-old woman sustained a combined right ACL and posterior horn medial meniscal injury while skiing in 1996. Following a 2-year nonoperative course, and after continued bouts of instability, the patient elected to proceed with an ACL reconstruction. At the time of the surgery, an unstable, medial meniscal, posterior horn tear with radial and longitudinal components was revealed. The radial component was debrided. The longitudinal component, lying within the red-white zone, was debrided with a meniscal rasp. After confirmation of vascular perfusion, four 10-mm PLA Clearfix meniscal screws were placed. After placement as directed by the manufacturer, the meniscus was noted to be stable and without evidence of fixator protrusion. The ACL was then reconstructed uneventfully using an autologous 4-stranded hamstring graft with closedloop EndoButton (Smith & Nephew, Mansfield, MA) femoral fixation and biodegradable interference screw tibial fixation with staple augmentation.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 3 (March), 2001: E11
1
2
W. F. SIMS AND P. T. SIMONIAN
Postoperatively, the patient was placed on our standard ACL rehabilitation protocol and she progressed without complication. The patient returned to full activities and had full range of motion. Repeat clinical examination revealed a grade IA Lachman and negative pivot shift. Seventeen months after the index procedure, the patient complained of mechanical symptoms localized on clinical examination to the posterior medial compartment of her right knee. On repeat arthroscopic examination, 18 months after the primary procedure, 2 undegraded PLA meniscal screws in an unstable segment of the posterior medial meniscus were found. The ACL graft was intact and well healed. Two PLA meniscal screw remnants were removed and the posterior medial meniscus debrided back to a stable rim (Fig 1). DISCUSSION The rationale for meniscal repair has been well established.11-15 The functional importance of the menisci in force transmission, stability, and shock absorption has led to a more conservative approach to the management of meniscal tears.16 Multiple methods of meniscal repair have been developed, with 3 techniques being used most commonly: the inside-out, outside-in, and the all-inside techniques. The all-inside technique described by Morgan in 199117 was developed for posterocentral tears of the menisci and is technically demanding. The technique often requires the use of a 70° arthroscope and posterior portal placement. Other types of all-inside repairs
FIGURE 1. The 2 undegraded PLA meniscal screws found in an unstable segment of the posterior medial meniscus after removal.
have evolved such as the suture hook and T-fix suture anchor, both of which require arthroscopic knot tying techniques. The use of bioabsorbable PLA meniscal fixators was reported in 1993 by Albrecht-Olsen et al.4 and, following Food and Drug Administration approval in 1997, this absorbable PLA fixator provided an attractive alternative to other methods of all-inside repair. The technique was considered a safe, simplified, allinside technique not dependent on an arthroscopic knot tying, posterior portal placement, or arthroscopes of varying degrees. The use of bioabsorbable fixation for meniscal repair is noted to be safe and effective.3,18 The use of bioabsorbable meniscal fixators requires less operative time than the use of standard vertical or horizontal sutures. Bovine studies have shown comparable pullout strength (53 N) in a comparison of meniscal arrows with Maxon horizontal mattress sutures.19 The developers of the Clearfix meniscal screw tout the advantages of quick readjustment and report that the compressive effect and superior pullout strength make the meniscal screw an attractive alternative to conventional suture technique and other PLA fixators.20 The meniscal screw is a molded PLA fixator. This bioabsorbable implant has been reported to have advantageous characteristics when compared with other PLA competitors, including greater holding strength, and greater bending fatigue endurance.20 The implants are designed to provide a biostable implant that minimizes soft-tissue inflammation and osteolysis while allowing for apposition of the torn meniscus during healing. Degradation of the PLA occurs from the center out, leaving an outer shell that progressively dissolves through hydrolysis. PLA has negligible rates of inflammatory reactions when compared with those of other polymers such as polyglycolic acid. The manufacturer of the Clearfix meniscal screw reports gradual reabsorption of the screws by 12 to 18 months. Relative to degradation, intrinsic velocity, a measure of the polymer’s resistance to flow, is noted to decrease from 2.47 dL/g at t ⫽ 0, to 1.40 dL/g at t ⫽ 52 weeks according to the manufacturer’s in vitro testing data. Complications of all-inside meniscal repairs using bioabsorbable meniscal fixators have not been widely reported. In a survey of surgeons using meniscal arrows taken in February of 1998, Cannon3 noted an overall complication rate of 3.4%. Among the complications were 4 infections, 3 loose extruded arrows, 1 case of reflex sympathetic dystrophy, 1 case of pain over the arrow tip, 1 stiff knee, and 1 case of deep
DELAYED DEGRADATION venous thrombosis. The series included 18 secondary operative procedures performed for a variety of reasons including fragmented arrows in 4 cases, 2 loose arrows, and 4 cases of arrows or arrow parts requiring removal. Cyst formation following all-inside repair has been reported.9,10,21 Arrow fracture and migration 6 months postoperatively has also been reported.22 Recently, concern of furrowing of retained intraarticular bioabsorbable implants into the surrounding articular cartilage has been reported.10 The case we present is intriguing in that the stable medial meniscal injury repaired in conjunction with ACL reconstruction failed. Moreover, the bioabsorbable meniscal fixators appeared unaltered at the time of their retrieval from the unstable meniscal fragment some 18 months after placement. In light of a recent report,10 concern is raised over the potential damaging effect to the articular cartilage of retained bioabsorbable implants. This case demonstrates 2 potential problems, retention and the risk of associated articular cartilage damage. Like other reports that have preceded it, these finding show the need for future investigation into the longterm effects of such implants.
6. 7. 8.
9. 10. 11. 12. 13. 14. 15. 16. 17.
REFERENCES
18.
1. DeHaven KE. Meniscal repair: Open vs. arthroscopic. Arthroscopy 1985;1:173-174. 2. Warren RF. Arthroscopic meniscal repair. Arthroscopy 1985; 1:170-172. 3. Cannon WD. Arthroscopic meniscal repair. Chicago: American Academy of Orthopaedic Surgeons, 1999;1-63. 4. Albrecht-Olsen P, Kristensen G, Tornala P. Meniscus buckethandle fixation with an absorbable Biofix tack: Development of a new technique. Knee Surg Sports Traumatol Arthrosc 1993;1:104-106. 5. Committee on Complications of the Arthroscopy Association
19.
20. 21. 22.
3
of North America. Complications in arthroscopy: The knee and other joints. Arthroscopy 1986;2:253-258. Stone RG, Frewin PR, Gonzales S. Long-term assessment of arthroscopic meniscus repair: A two-year and six-year follow-up study. Arthroscopy 1990;6:73-78. Austin KS, Sherman OH. Complications of arthroscopic meniscal repair. Am J Sports Med 1993;21:864-868. Scott GA, Jolly BL, Henning CE. Combined posterior incision and arthroscopic intra-articular repair of the meniscus: An examination of the factors affecting healing. J Bone Joint Surg Am 1986;68:847-861. Hechtman KS, Uribe JW. Cystic hematoma formation following use of a biodegradable arrow for meniscal repair. Arthroscopy 1999;15:207-210. Tingstad E, Teitz C, Simonian PT. Complications associated with the use of meniscal arrows. Am J Sports Med (in press). Cox JS, Nye CE, Schaefer WW, Woodstein IJ. The degenerative effects of partial and total resection of the medial meniscus in dog’s knees. Clin Orthop 1975;109:178-183. Huckell JR. Is meniscectomy a benign procedure? A long-term follow-up study. Can J Surg 1965;8:254-260. Jones RE, Smith EC, Reisch JS. Effects of medial meniscectomy in patients older than forty years. J Bone Joint Surg Am 1978;60:783-786. Moskowitz RW, Davis W, Sanmarco J, et al. Experimentally induced degenerative joint lesions following partial meniscectomy in the rabbit. Arthritis Rheum 1973;16:397-405. Tapper EM, Hoover NW. Late results after meniscectomy. J Bone Joint Surg Am 1969;51:517-526. DeHaven KE, Arnoczky SP. Meniscal repair. Instructional course lecture. J Bone Joint Surg Am 1994;76:140-152. Morgan CD. The “all-inside” meniscal repair. Arthroscopy 1991;7:120-125. Cohen B, Tasto J. Meniscal arrow. Tech Orthop 1998;13:164169. Albrecht-Olsen P, Lind T, Kristensen G, Falkenberg B. Failure strength of new Meniscus Arrow repair technique: Biomechanical comparison with horizontal suture. Arthroscopy 1997; 13:183-187. Winters T, Justin D. Clearfix™ meniscal screw: Clinical design rationale and summary. Marlborough, MA: Innovasive Devices, Inc, 1998. Lombardo SEV. Meniscal cyst formation after all-inside meniscal repair. Am J Sports Med 1999;27:666-667. Calder S, Myers PT. Broken arrow: A complication of meniscal repair. Arthroscopy 1999;15:651-652.
Delayed Degradation of Bioabsorbable Meniscal Fixators William F. Sims, M.D., and Peter T. Simonian, M.D.
Abstract: A greater understanding of the functional importance of the meniscus has prompted a more aggressive approach to conserving meniscal tissue. Multiple treatment options exist when dealing with a tear of the meniscus. As the popularity of bioabsorbable implants in the orthopaedic armamentarium grows, concern exists as to the potential associated complications. We describe a case of the failure of a bioabsorbable meniscal fixator appropriately applied to a posterior medial meniscal tear with an associated injury of the anterior cruciate ligament. Moreover, the concern of implant retention secondary to delayed degradation and resultant potential for articular cartilage damage was present. Key Words: Meniscus—Tear—Bioabsorbable—Fixator—Degradation—Implants
M
eniscal repair has been shown to be beneficial and safe.1-3 The use of bioabsorbable meniscal fixation has become increasingly popular. Since gaining approval of the Food and Drug Administration in 1997, the use of polylactic acid (PLA) meniscal implants have been believed to provide a safe and simplified all-inside technique of meniscal repair, with limited reported complications.4-9 Recently, the concern of abrasion and furrowing of articular cartilage by retained PLA meniscal implants has been reported.10 We present the case of a 23-year-old woman who had undergone an anterior cruciate ligament (ACL) reconstruction and repair of a longitudinal, posterior horn, medial meniscus tear that was stabilized with PLA Clearfix meniscal screws (Innovasive Devices, Marlborough, MA). Seventeen months after the index procedure, the patient presented with a complaint of
From the Department of Orthopaedic Surgery and Sports Medicine, The University of Washington, Seattle, Washington, U.S.A. Address correspondence and reprint requests to Peter T. Simonian, M.D., Department of Orthopaedic Surgery and Sports Medicine, The University of Washington, Box 356500, Seattle, WA 98195, U.S.A. E-mail: [email protected] © 2001 by the Arthroscopy Association of North America 1526-3231/01/1703-2772$35.00/0 doi:10.1053/jars.2001.20668
mechanical symptoms that, on examination, were found to be localized to the posterior medial compartment of the patient’s knee.
CASE REPORT An athletic 23-year-old woman sustained a combined right ACL and posterior horn medial meniscal injury while skiing in 1996. Following a 2-year nonoperative course, and after continued bouts of instability, the patient elected to proceed with an ACL reconstruction. At the time of the surgery, an unstable, medial meniscal, posterior horn tear with radial and longitudinal components was revealed. The radial component was debrided. The longitudinal component, lying within the red-white zone, was debrided with a meniscal rasp. After confirmation of vascular perfusion, four 10-mm PLA Clearfix meniscal screws were placed. After placement as directed by the manufacturer, the meniscus was noted to be stable and without evidence of fixator protrusion. The ACL was then reconstructed uneventfully using an autologous 4-stranded hamstring graft with closedloop EndoButton (Smith & Nephew, Mansfield, MA) femoral fixation and biodegradable interference screw tibial fixation with staple augmentation.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 3 (March), 2001: E11
1
2
W. F. SIMS AND P. T. SIMONIAN
Postoperatively, the patient was placed on our standard ACL rehabilitation protocol and she progressed without complication. The patient returned to full activities and had full range of motion. Repeat clinical examination revealed a grade IA Lachman and negative pivot shift. Seventeen months after the index procedure, the patient complained of mechanical symptoms localized on clinical examination to the posterior medial compartment of her right knee. On repeat arthroscopic examination, 18 months after the primary procedure, 2 undegraded PLA meniscal screws in an unstable segment of the posterior medial meniscus were found. The ACL graft was intact and well healed. Two PLA meniscal screw remnants were removed and the posterior medial meniscus debrided back to a stable rim (Fig 1). DISCUSSION The rationale for meniscal repair has been well established.11-15 The functional importance of the menisci in force transmission, stability, and shock absorption has led to a more conservative approach to the management of meniscal tears.16 Multiple methods of meniscal repair have been developed, with 3 techniques being used most commonly: the inside-out, outside-in, and the all-inside techniques. The all-inside technique described by Morgan in 199117 was developed for posterocentral tears of the menisci and is technically demanding. The technique often requires the use of a 70° arthroscope and posterior portal placement. Other types of all-inside repairs
FIGURE 1. The 2 undegraded PLA meniscal screws found in an unstable segment of the posterior medial meniscus after removal.
have evolved such as the suture hook and T-fix suture anchor, both of which require arthroscopic knot tying techniques. The use of bioabsorbable PLA meniscal fixators was reported in 1993 by Albrecht-Olsen et al.4 and, following Food and Drug Administration approval in 1997, this absorbable PLA fixator provided an attractive alternative to other methods of all-inside repair. The technique was considered a safe, simplified, allinside technique not dependent on an arthroscopic knot tying, posterior portal placement, or arthroscopes of varying degrees. The use of bioabsorbable fixation for meniscal repair is noted to be safe and effective.3,18 The use of bioabsorbable meniscal fixators requires less operative time than the use of standard vertical or horizontal sutures. Bovine studies have shown comparable pullout strength (53 N) in a comparison of meniscal arrows with Maxon horizontal mattress sutures.19 The developers of the Clearfix meniscal screw tout the advantages of quick readjustment and report that the compressive effect and superior pullout strength make the meniscal screw an attractive alternative to conventional suture technique and other PLA fixators.20 The meniscal screw is a molded PLA fixator. This bioabsorbable implant has been reported to have advantageous characteristics when compared with other PLA competitors, including greater holding strength, and greater bending fatigue endurance.20 The implants are designed to provide a biostable implant that minimizes soft-tissue inflammation and osteolysis while allowing for apposition of the torn meniscus during healing. Degradation of the PLA occurs from the center out, leaving an outer shell that progressively dissolves through hydrolysis. PLA has negligible rates of inflammatory reactions when compared with those of other polymers such as polyglycolic acid. The manufacturer of the Clearfix meniscal screw reports gradual reabsorption of the screws by 12 to 18 months. Relative to degradation, intrinsic velocity, a measure of the polymer’s resistance to flow, is noted to decrease from 2.47 dL/g at t ⫽ 0, to 1.40 dL/g at t ⫽ 52 weeks according to the manufacturer’s in vitro testing data. Complications of all-inside meniscal repairs using bioabsorbable meniscal fixators have not been widely reported. In a survey of surgeons using meniscal arrows taken in February of 1998, Cannon3 noted an overall complication rate of 3.4%. Among the complications were 4 infections, 3 loose extruded arrows, 1 case of reflex sympathetic dystrophy, 1 case of pain over the arrow tip, 1 stiff knee, and 1 case of deep
DELAYED DEGRADATION venous thrombosis. The series included 18 secondary operative procedures performed for a variety of reasons including fragmented arrows in 4 cases, 2 loose arrows, and 4 cases of arrows or arrow parts requiring removal. Cyst formation following all-inside repair has been reported.9,10,21 Arrow fracture and migration 6 months postoperatively has also been reported.22 Recently, concern of furrowing of retained intraarticular bioabsorbable implants into the surrounding articular cartilage has been reported.10 The case we present is intriguing in that the stable medial meniscal injury repaired in conjunction with ACL reconstruction failed. Moreover, the bioabsorbable meniscal fixators appeared unaltered at the time of their retrieval from the unstable meniscal fragment some 18 months after placement. In light of a recent report,10 concern is raised over the potential damaging effect to the articular cartilage of retained bioabsorbable implants. This case demonstrates 2 potential problems, retention and the risk of associated articular cartilage damage. Like other reports that have preceded it, these finding show the need for future investigation into the longterm effects of such implants.
6. 7. 8.
9. 10. 11. 12. 13. 14. 15. 16. 17.
REFERENCES
18.
1. DeHaven KE. Meniscal repair: Open vs. arthroscopic. Arthroscopy 1985;1:173-174. 2. Warren RF. Arthroscopic meniscal repair. Arthroscopy 1985; 1:170-172. 3. Cannon WD. Arthroscopic meniscal repair. Chicago: American Academy of Orthopaedic Surgeons, 1999;1-63. 4. Albrecht-Olsen P, Kristensen G, Tornala P. Meniscus buckethandle fixation with an absorbable Biofix tack: Development of a new technique. Knee Surg Sports Traumatol Arthrosc 1993;1:104-106. 5. Committee on Complications of the Arthroscopy Association
19.
20. 21. 22.
3
of North America. Complications in arthroscopy: The knee and other joints. Arthroscopy 1986;2:253-258. Stone RG, Frewin PR, Gonzales S. Long-term assessment of arthroscopic meniscus repair: A two-year and six-year follow-up study. Arthroscopy 1990;6:73-78. Austin KS, Sherman OH. Complications of arthroscopic meniscal repair. Am J Sports Med 1993;21:864-868. Scott GA, Jolly BL, Henning CE. Combined posterior incision and arthroscopic intra-articular repair of the meniscus: An examination of the factors affecting healing. J Bone Joint Surg Am 1986;68:847-861. Hechtman KS, Uribe JW. Cystic hematoma formation following use of a biodegradable arrow for meniscal repair. Arthroscopy 1999;15:207-210. Tingstad E, Teitz C, Simonian PT. Complications associated with the use of meniscal arrows. Am J Sports Med (in press). Cox JS, Nye CE, Schaefer WW, Woodstein IJ. The degenerative effects of partial and total resection of the medial meniscus in dog’s knees. Clin Orthop 1975;109:178-183. Huckell JR. Is meniscectomy a benign procedure? A long-term follow-up study. Can J Surg 1965;8:254-260. Jones RE, Smith EC, Reisch JS. Effects of medial meniscectomy in patients older than forty years. J Bone Joint Surg Am 1978;60:783-786. Moskowitz RW, Davis W, Sanmarco J, et al. Experimentally induced degenerative joint lesions following partial meniscectomy in the rabbit. Arthritis Rheum 1973;16:397-405. Tapper EM, Hoover NW. Late results after meniscectomy. J Bone Joint Surg Am 1969;51:517-526. DeHaven KE, Arnoczky SP. Meniscal repair. Instructional course lecture. J Bone Joint Surg Am 1994;76:140-152. Morgan CD. The “all-inside” meniscal repair. Arthroscopy 1991;7:120-125. Cohen B, Tasto J. Meniscal arrow. Tech Orthop 1998;13:164169. Albrecht-Olsen P, Lind T, Kristensen G, Falkenberg B. Failure strength of new Meniscus Arrow repair technique: Biomechanical comparison with horizontal suture. Arthroscopy 1997; 13:183-187. Winters T, Justin D. Clearfix™ meniscal screw: Clinical design rationale and summary. Marlborough, MA: Innovasive Devices, Inc, 1998. Lombardo SEV. Meniscal cyst formation after all-inside meniscal repair. Am J Sports Med 1999;27:666-667. Calder S, Myers PT. Broken arrow: A complication of meniscal repair. Arthroscopy 1999;15:651-652.