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Tibial cyst formation after anterior cruciate ligament reconstruction using a new bioabsorbable screw
The Knee 9 Ž2002. 73᎐75
Case report
Tibial cyst formation after anterior cruciate ligament reconstruction using a new bioabsorbable screw K. MalhanU , A. Kumar, D. Rees Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire, SY10 7AG, UK Received 12 March 2001; received in revised form 23 May 2001; accepted 7 June 2001
Abstract We report a case of tibial cyst formation twelve months after anterior cruciate ligament reconstruction using hamstring graft. A composite bioabsorbable interference screw made of ‘beta tricalcium phosphate and poly L-lactide’ fixed the graft distally. The patient presented with acute symptoms of pain and swelling over the proximal tibia. Curettage of the cyst resulted in complete recovery within 3 months. 䊚 2002 Elsevier Science B.V. All rights reserved. Keywords: Tibial cyst; Bioabsorbable screw; Anterior cruciate ligament reconstruction
1. Introduction Bioabsorbable screws have been used for the fixation of grafts in anterior cruciate ligament reconstruction. These screws are made up of polymers that vary in their crystallinity and degradation behaviour. BioLok ŽAtlantech Medical Devices Ltd, Harrogate, UK. is a composite polymer interference screw of poly-Llactide and beta tricalcium phosphate. Complications like screw breakage w1x, synovitis w2x and pretibial cyst w3x formation have been reported in literature with other polymer screws. We report a case of a tibial cyst formation after using BioLok screw for fixation of the hamstring graft.
2. Case report A 22-year-old lady presented with 6 months history U
Corresponding author. Tel.: q44-1691-404435; fax: q44-1691404071. E-mail address: [email protected] ŽK. Malhan..
of right knee instability following a twisting injury. She had sustained an isolated rupture of the anterior cruciate ligament ŽACL.. The ligament was reconstructed using hamstring graft, which was fixed proximally with a transfemoral metal screw and distally with a BioLok interference screw. The patient made a satisfactory recovery and returned to pre injury level of activity in 6 months. Twelve months after the operation, the patient attended casualty with pain and swelling over the proximal tibia. On examination, there was a small tender swelling over the operative site, but the local temperature was normal. She had a full range of movements with no evidence of synovitis or instability in the knee. Routine blood investigations like full blood count, ESR and CRP were within normal limits. Plain radiograph showed cystic expansion of the tibial tunnel ŽFig. 1.. An MRI scan confirmed cystic expansion of the distal two-thirds of the tibial tunnel with increased signal intensity on T2 and STIR sequences. The cyst did not appear to communicate with the joint. The screw was not seen and the graft looked intact ŽFig. 2.. The patient was taken to theatre for exploration of
0968-0160r02r$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 6 8 - 0 1 6 0 Ž 0 1 . 0 0 1 0 9 - 0
74
K. Malhan et al. r The Knee 9 (2002) 73᎐75
Benedetto et al. reported formation of a pretibial cyst in one patient, 6 months after ACL reconstruction using PGA screws in a group of 67 patients w5x. The poly D-L-lactide ŽPDLLA. screw has a slower degradation rate than PGA w7x. However, tibial cyst formation after using this interference screw has also been reported w3x. Implants made of poly L-lactide ŽPLLA. have better mechanical properties. Their slow degradation rate produces lower concentrations of end products like lactic acid. However, they breakdown into crystalline fragments which can cause a foreign body reaction w7x. The BIOLOK screw used in our case is a composite in which tricalcium phosphate replaces a portion of the PLLA to reduce crystalline fragmentation, allow slower breakdown and provide osteoconductive potential. In a study, which reported good results with pure PLLA screws in ACL reconstruction, the only screw that was noted to have disappeared early on the MRI scan had cracked during insertion w8x. The broken screw resorbs more quickly because of its increased surface area, consequently producing larger concentrations of lactic acid. Ordinarily, one would expect
Fig. 1. AP radiograph of the knee showing expansion of the distal part of the tibial tunnel.
the tibial tunnel. On examination under anaesthesia, the knee was found to be stable. The tunnel was explored through the old incision. The entry hole was found to be widened and covered with fibrous tissue. On removing the fibrous tissue, gelatinous material came out of the tunnel. Most of the screw had disappeared and only a small fragment was found. The cyst was curetted and the tissue was sent for culture and histological examination. The culture did not show growth of any microorganisms and histology showed only a few giant cells and macrophages. At 3 months follow-up, the patient was asymptomatic and returned to normal activities. The knee was clinically stable.
3. Discussion Biodegradable polymer implants have been used both for the fixation of fractures and as interference screws in ACL reconstruction. A high incidence of osteolysis has been reported after using polyglyconate ŽPGA. implants for fixation of ankle fracture due to their rapid degradation w4x. However, some studies on ACL reconstruction have shown good results after using interference screws of the same material w5,6x.
Fig. 2. MRI scan, sagittal section, T2 weighted image showing cystic expansion of the distal part of the tibial tunnel with a high signal intensity.
K. Malhan et al. r The Knee 9 (2002) 73᎐75
this to clear away, but a tunnel that is tightly closed at both ends will only allow this to happen very slowly. This leads to a gradual accumulation of breakdown products Žcontainer phenomenon. that can produce osteolysis w9x. A similar mechanism could have resulted in cyst formation in our case. Subcutaneous pretibial cyst has been reported after ACL reconstruction with both allografts and autografts after using metal implants for graft fixation w10,11x. Incomplete allograft incorporation, graft necrosis and transmission of synovial fluid to the pretibial area in one study and synovialisation of the autograft in another were postulated as possible mechanisms w10,11x. These cases did not have bony involvement. Our case report suggests that adverse reactions to bioabsorbable implants continue to occur in spite of alterations in their composition. If the problems were with the screw composition, one would expect this complication more often than is normally observed. Though it is possible that asymptomatic cystic changes could go undetected unless routine radiographic examinations are carried out at follow-up, we believe that factors such as screw breakage and the container phenomenon are as important as the chemical composition of the screw.
w3x
w4x
w5x
w6x
w7x
w8x
w9x
w10x
References w1x Barber FA, Elrod BF, McGuire DA, Paulos LE. Preliminary results of an absorbable interference screw. Arthroscopy 1995;11:537᎐548. w2x Takizawa T, Akizuki S, Horiuchi H, Yasukawa Y. Foreign
w11x
75
body gonitis caused by a broken poly-L-lactic acid screw. Arthroscopy 1998;14:329᎐330. Martinek V, Friederich NF. Tibial and pretibial cyst formation after anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation. Arthroscopy 1999;15:317᎐320. Bostman OM. Osteolytic changes accompanying degradation of absorbable fracture fixation implants. J Bone Joint Surg wBrx 1991;73B:679᎐682. Benedetto KP, Fellinger M, Lim TE, Passler JM, Schoen JL, Willems WJ. A new bioabsorbable interference screw: preliminary results of a prospective, multicentre, randomized clinical trial. Arthroscopy 2000;16:41᎐48. Fink C, Benedetto KP, Hackl W, Hoser C, Freund MC, Rieger M. Bioabsorbable polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: a prospective computed tomography-controlled study. Arthroscopy 2000;16:491᎐498. Stahelin AC, Weiler A, Rufenacht H, Hoffmann R, Geeismann A, Feinstein R. Clinical degradation and biocompatibility of different bioabsorbable interference screws. A report of six cases. Arthroscopy 1997;13:238᎐244. Warden WH, Friedman R, Teresi LM, Jackson DW. Magnetic resonance imaging of bioabsorbable polylactic acid interference screws during the first 2 years after anterior cruciate ligament reconstruction. Arthroscopy 1999;15:474᎐480. Weiler A, Helling H-J, Kirch U, Zirbes TK, Rehm KE. Foreign body reaction and the course of osteolysis after polyglycolide implants for fracture fixation. Experimental study in sheep. J Bone Joint Surg ŽBr. 1996;78-B:369᎐376. Victoroff BN, Paulos L, Beck C, Goodfellow DB. Subcutaneous pretibial cyst formation associated with anterior cruciate ligament allografts: a report of four cases and literature review. Arthroscopy 1995;11:486᎐494. Simoman PT, Wickiewicz TL, O’Brien SJ, Dines JS, Schatz JA, Warren RF. Pretibial cyst formation after anterior cruciate ligament surgery with soft tissue autografts. Arthroscopy 1998;14:215᎐220.
Case report
Tibial cyst formation after anterior cruciate ligament reconstruction using a new bioabsorbable screw K. MalhanU , A. Kumar, D. Rees Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire, SY10 7AG, UK Received 12 March 2001; received in revised form 23 May 2001; accepted 7 June 2001
Abstract We report a case of tibial cyst formation twelve months after anterior cruciate ligament reconstruction using hamstring graft. A composite bioabsorbable interference screw made of ‘beta tricalcium phosphate and poly L-lactide’ fixed the graft distally. The patient presented with acute symptoms of pain and swelling over the proximal tibia. Curettage of the cyst resulted in complete recovery within 3 months. 䊚 2002 Elsevier Science B.V. All rights reserved. Keywords: Tibial cyst; Bioabsorbable screw; Anterior cruciate ligament reconstruction
1. Introduction Bioabsorbable screws have been used for the fixation of grafts in anterior cruciate ligament reconstruction. These screws are made up of polymers that vary in their crystallinity and degradation behaviour. BioLok ŽAtlantech Medical Devices Ltd, Harrogate, UK. is a composite polymer interference screw of poly-Llactide and beta tricalcium phosphate. Complications like screw breakage w1x, synovitis w2x and pretibial cyst w3x formation have been reported in literature with other polymer screws. We report a case of a tibial cyst formation after using BioLok screw for fixation of the hamstring graft.
2. Case report A 22-year-old lady presented with 6 months history U
Corresponding author. Tel.: q44-1691-404435; fax: q44-1691404071. E-mail address: [email protected] ŽK. Malhan..
of right knee instability following a twisting injury. She had sustained an isolated rupture of the anterior cruciate ligament ŽACL.. The ligament was reconstructed using hamstring graft, which was fixed proximally with a transfemoral metal screw and distally with a BioLok interference screw. The patient made a satisfactory recovery and returned to pre injury level of activity in 6 months. Twelve months after the operation, the patient attended casualty with pain and swelling over the proximal tibia. On examination, there was a small tender swelling over the operative site, but the local temperature was normal. She had a full range of movements with no evidence of synovitis or instability in the knee. Routine blood investigations like full blood count, ESR and CRP were within normal limits. Plain radiograph showed cystic expansion of the tibial tunnel ŽFig. 1.. An MRI scan confirmed cystic expansion of the distal two-thirds of the tibial tunnel with increased signal intensity on T2 and STIR sequences. The cyst did not appear to communicate with the joint. The screw was not seen and the graft looked intact ŽFig. 2.. The patient was taken to theatre for exploration of
0968-0160r02r$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 6 8 - 0 1 6 0 Ž 0 1 . 0 0 1 0 9 - 0
74
K. Malhan et al. r The Knee 9 (2002) 73᎐75
Benedetto et al. reported formation of a pretibial cyst in one patient, 6 months after ACL reconstruction using PGA screws in a group of 67 patients w5x. The poly D-L-lactide ŽPDLLA. screw has a slower degradation rate than PGA w7x. However, tibial cyst formation after using this interference screw has also been reported w3x. Implants made of poly L-lactide ŽPLLA. have better mechanical properties. Their slow degradation rate produces lower concentrations of end products like lactic acid. However, they breakdown into crystalline fragments which can cause a foreign body reaction w7x. The BIOLOK screw used in our case is a composite in which tricalcium phosphate replaces a portion of the PLLA to reduce crystalline fragmentation, allow slower breakdown and provide osteoconductive potential. In a study, which reported good results with pure PLLA screws in ACL reconstruction, the only screw that was noted to have disappeared early on the MRI scan had cracked during insertion w8x. The broken screw resorbs more quickly because of its increased surface area, consequently producing larger concentrations of lactic acid. Ordinarily, one would expect
Fig. 1. AP radiograph of the knee showing expansion of the distal part of the tibial tunnel.
the tibial tunnel. On examination under anaesthesia, the knee was found to be stable. The tunnel was explored through the old incision. The entry hole was found to be widened and covered with fibrous tissue. On removing the fibrous tissue, gelatinous material came out of the tunnel. Most of the screw had disappeared and only a small fragment was found. The cyst was curetted and the tissue was sent for culture and histological examination. The culture did not show growth of any microorganisms and histology showed only a few giant cells and macrophages. At 3 months follow-up, the patient was asymptomatic and returned to normal activities. The knee was clinically stable.
3. Discussion Biodegradable polymer implants have been used both for the fixation of fractures and as interference screws in ACL reconstruction. A high incidence of osteolysis has been reported after using polyglyconate ŽPGA. implants for fixation of ankle fracture due to their rapid degradation w4x. However, some studies on ACL reconstruction have shown good results after using interference screws of the same material w5,6x.
Fig. 2. MRI scan, sagittal section, T2 weighted image showing cystic expansion of the distal part of the tibial tunnel with a high signal intensity.
K. Malhan et al. r The Knee 9 (2002) 73᎐75
this to clear away, but a tunnel that is tightly closed at both ends will only allow this to happen very slowly. This leads to a gradual accumulation of breakdown products Žcontainer phenomenon. that can produce osteolysis w9x. A similar mechanism could have resulted in cyst formation in our case. Subcutaneous pretibial cyst has been reported after ACL reconstruction with both allografts and autografts after using metal implants for graft fixation w10,11x. Incomplete allograft incorporation, graft necrosis and transmission of synovial fluid to the pretibial area in one study and synovialisation of the autograft in another were postulated as possible mechanisms w10,11x. These cases did not have bony involvement. Our case report suggests that adverse reactions to bioabsorbable implants continue to occur in spite of alterations in their composition. If the problems were with the screw composition, one would expect this complication more often than is normally observed. Though it is possible that asymptomatic cystic changes could go undetected unless routine radiographic examinations are carried out at follow-up, we believe that factors such as screw breakage and the container phenomenon are as important as the chemical composition of the screw.
w3x
w4x
w5x
w6x
w7x
w8x
w9x
w10x
References w1x Barber FA, Elrod BF, McGuire DA, Paulos LE. Preliminary results of an absorbable interference screw. Arthroscopy 1995;11:537᎐548. w2x Takizawa T, Akizuki S, Horiuchi H, Yasukawa Y. Foreign
w11x
75
body gonitis caused by a broken poly-L-lactic acid screw. Arthroscopy 1998;14:329᎐330. Martinek V, Friederich NF. Tibial and pretibial cyst formation after anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation. Arthroscopy 1999;15:317᎐320. Bostman OM. Osteolytic changes accompanying degradation of absorbable fracture fixation implants. J Bone Joint Surg wBrx 1991;73B:679᎐682. Benedetto KP, Fellinger M, Lim TE, Passler JM, Schoen JL, Willems WJ. A new bioabsorbable interference screw: preliminary results of a prospective, multicentre, randomized clinical trial. Arthroscopy 2000;16:41᎐48. Fink C, Benedetto KP, Hackl W, Hoser C, Freund MC, Rieger M. Bioabsorbable polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: a prospective computed tomography-controlled study. Arthroscopy 2000;16:491᎐498. Stahelin AC, Weiler A, Rufenacht H, Hoffmann R, Geeismann A, Feinstein R. Clinical degradation and biocompatibility of different bioabsorbable interference screws. A report of six cases. Arthroscopy 1997;13:238᎐244. Warden WH, Friedman R, Teresi LM, Jackson DW. Magnetic resonance imaging of bioabsorbable polylactic acid interference screws during the first 2 years after anterior cruciate ligament reconstruction. Arthroscopy 1999;15:474᎐480. Weiler A, Helling H-J, Kirch U, Zirbes TK, Rehm KE. Foreign body reaction and the course of osteolysis after polyglycolide implants for fracture fixation. Experimental study in sheep. J Bone Joint Surg ŽBr. 1996;78-B:369᎐376. Victoroff BN, Paulos L, Beck C, Goodfellow DB. Subcutaneous pretibial cyst formation associated with anterior cruciate ligament allografts: a report of four cases and literature review. Arthroscopy 1995;11:486᎐494. Simoman PT, Wickiewicz TL, O’Brien SJ, Dines JS, Schatz JA, Warren RF. Pretibial cyst formation after anterior cruciate ligament surgery with soft tissue autografts. Arthroscopy 1998;14:215᎐220.