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Veterinarni medicina2023; 68(7); 259-270; doi: 10.17221/52/2023-VETMED

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine.

Abstract: Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.
Publication Date: 2023-07-27 PubMed ID: 37982051PubMed Central: PMC10581530DOI: 10.17221/52/2023-VETMEDGoogle Scholar: Lookup
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  • Journal Article
  • Review

Summary

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Overview

  • This research article reviews and compares the reasons for removing bone implants after fracture healing in both human and veterinary medicine, highlighting the lack of clear guidelines and consensus in this area.

Introduction

  • Implants such as screws, plates, and rods are commonly used to stabilize fractures in bones during healing.
  • Removal of these implants after the bone has healed is a frequent procedure but carries risks.
  • There remains ongoing debate about when and why implants should be removed in both humans and animals.

Aims of the Review

  • To collect and summarize existing data on the indications for implant removal specifically in small animals (pets like dogs and cats).
  • To compare these findings with data from human orthopedics and equine (horse) veterinary medicine.
  • To assess whether there are established clinical guidelines or consensus protocols for implant removal after fracture healing in any of these medical fields.

Findings: Lack of Consensus

  • Currently, there is no international or universally accepted agreement regarding when or whether to remove implants following fracture healing.
  • This absence of consensus applies to small animal veterinary medicine as well as human orthopedics.
  • In equine medicine, similar uncertainty and differing practices exist, though the article primarily focuses on small animals and humans.

Complications of Implant Removal

  • The surgery to remove implants is not without risks and can lead to intra-operative (during surgery) and post-operative (after surgery) complications.
  • These complications can sometimes be serious, prompting the need for careful risk-benefit analysis before attempting removal.
  • Complications may include infection, damage to surrounding tissues, refracture, or prolonged recovery time.

Clinical Decision Making

  • Decisions on implant removal are often based on individual patient factors, symptoms such as pain or irritation, implant-related problems, or owner/patient preference.
  • In many scenarios, the choice to remove hardware remains controversial due to lack of definitive evidence guiding best practices.
  • Surgeons and veterinarians must weigh risks and benefits on a case-by-case basis, sometimes without the support of clear evidence-based protocols.

Need for Evidence-Based Protocols

  • The review highlights the critical need for well-designed studies to develop evidence-based guidelines for implant removal.
  • Such protocols would help standardize care, improve patient outcomes, and reduce unnecessary surgery or complications.
  • Developing consensus would help both human and veterinary medicine practitioners make informed decisions regarding implant management post-fracture healing.

Conclusion

  • Implant removal after bone fracture healing remains a debated issue with no clear international guidelines.
  • The review underscores the importance of further research and consensus-building across both human and veterinary orthopedics.
  • Until then, careful evaluation and individualized decision-making remain essential to balance the risks and benefits of implant removal.

Cite This Article

APA
Andrade MC, De Rus Aznar I, Brunnberg M, Slunsky P. (2023). Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine. Vet Med (Praha), 68(7), 259-270. https://doi.org/10.17221/52/2023-VETMED

Publication

ISSN: 0375-8427
NlmUniqueID: 0063417
Country: Czech Republic
Language: English
Volume: 68
Issue: 7
Pages: 259-270

Researcher Affiliations

Andrade, Mario Candela
  • Department of Human Anatomy, Health and Medical University Potsdam, Potsdam, Brandenburg, Germany.
De Rus Aznar, Ignacio
  • Orthopaedic Surgery and Traumatology, University Hospital of Torrejón, Madrid, Spain; Shoulder and Knee Surgery Department, Olympia Quironsalud Hospital, Madrid, Spain.
Brunnberg, Mathias
  • Surgical Department, Small Animal Clinic, Tierarztpraxis Sörensen, Berlin, Germany.
Slunsky, Pavel
  • Surgical Department, Small Animal Hospital, Anicura Kleintierspezialisten Augsburg, Augsburg, Bavaria, Germany.

Conflict of Interest Statement

The authors declare no conflict of interest.

References

This article includes 78 references
  1. Acklin YP, Bircher A, Morgenstern M, Richards RG, Sommer C. Benefits of hardware removal after plating.. Injury 2018 Jun;49(Suppl_1):91-5.
    pubmed: 29929702
  2. Arthur EG, Arthur GL, Keeler MR, Bryan JN. Risk of osteosarcoma in dogs after open fracture fixation.. Vet Surg 2016 Jan;45(1):30-5.
    pubmed: 26595882
  3. Auer JA, Grainger DW. Fracture management in horses: Where have we been and where are we going?. Vet J 2015 Oct;206(1):5-14.
    pubmed: 26095036
  4. Batash R, Debi R, Grinberg D, Shema M, Elbaz A, Benedict Y. Mechanical failure of plate breakage after open reduction and plate fixation of displaced midshaft clavicle fracture – A possible new risk factor: A case report.. J Med Case Rep 2019 Apr 28;13(1):127.
    pmc: PMC6487008pubmed: 31029151
  5. Bergman BR. Antibiotic prophylaxis in open and closed fractures: A controlled clinical trial.. Acta Orthop Scand 1982 Feb;53(1):57-62.
    pubmed: 7064681
  6. Berkes M, Obremskey WT, Scannell B, Ellington JK, Hymes RA, Bosse M. Maintenance of hardware after early postoperative infection following fracture internal fixation.. J Bone Joint Surg Am 2010 Apr;92(4):823-8.
    pubmed: 20360504
  7. Bischofberger AS, Furst A, Auer J, Lischer C. Surgical management of complete diaphyseal third metacarpal and metatarsal bone fractures: Clinical outcome in 10 mature horses and 11 foals.. Equine Vet J 2009 May;41(5):465-73.
    pubmed: 19642407
  8. Bos RR, Rozema FR, Boering G, Nijenhuis AJ, Pennings AJ, Verwey AB. Bio-absorbable plates and screws for internal fixation of mandibular fractures. A study in six dogs.. Int J Oral Maxillofac Surg 1989 Dec;18(6):365-9.
    pubmed: 2516105
  9. Boudrieau RJ, McCarthy RJ, Sisson RD Jr. Sarcoma of the proximal portion of the tibia in a dog 5.5 years after tibial plateau leveling osteotomy.. J Am Vet Med Assoc 2005 Nov 15;227(10):1613-7, 1591.
    pubmed: 16313039
  10. Braun R, Enzler MA, Rittmann WW. A double-blind clinical trial of prophylactic cloxacillin in open fractures.. J Orthop Trauma 1987;1(1):12-7.
    pubmed: 3333512
  11. Brinker WO, Piermattei DL, Flo GL. Fractures and corrective surgery in young growing animals: Handbook of small animal orthopedics and fracture treatment.. 2 ed. Philadelphia: WB Saunders Co.; 1990. p. 244-56.
  12. Brinker WO. Removal of implants.. In: Brinker WO, Olmstead ML, Sumner-Smith G, Prieur WD, editors. Manual of internal fixation in small animals. 2 ed. Berlin, Heidelberg: Springer-Verlag; 2013. p. 265-6.
  13. Burton AG, Johnson EG, Vernau W, Murphy BG. Implant-associated neoplasia in dogs: 16 cases (1983–2013).. J Am Vet Med Assoc 2015 Oct 1;247(7):778-85.
    pubmed: 26383754
  14. DGU – Deutschen Gesellschaft für Unfallchirurgie e.V.. Implantatentfernung nach Osteosynthese [Implantate removal after osteosynsthesis].. AWMF-Nr. 012-004. 2018. Berlin: German Society Trauma Surgery; 2018. German.
  15. Donati B, Furst AE, Del Chicca F, Jackson MA. Plate removal after internal fixation of limb fractures: A retrospective study of indications and complications in 48 horses.. Vet Comp Orthop Traumatol 2021 Jan;34(1):59-67.
    pubmed: 32799311
  16. Dunn AL, Buffa EA, Hanshaw DM, Farrell M. Osteosarcoma at the site of titanium orthopaedic implants in a dog. Aust Vet J 2012 Jan-Feb;90(1-2):39-43.
    pubmed: 22256984
  17. Eijer H, Hauke C, Arens S, Printzen G, Schlegel U, Perren SM. PC-Fix and local infection resistance – Influence of implant design on postoperative infection development, clinical and experimental results. Injury 2001 Sep;32(Suppl_2):B38-43.
    pubmed: 11718737
  18. Emmerson TD, Muir P. Bone plate removal in dogs and cats. Vet Comp Orthop Traumatol 1999;12(2):74-7.
  19. Evers B, Habelt R, Gerngross H. O2109 indication, timing and complications of plate removal after forearm fractures: Results of a metanalysis including 635 cases. Bone Joint Surg Br 2004;86:289.
  20. Field MR, Butler R, Wills RW, Maxwell WM. Retrospective evaluation of perioperative and short term clinical outcomes in appendicular long bone skeleton fractures repaired via the string of pearls (SOP) locking plate system. BMC Vet Res 2018 Dec 5;14(1):386.
    pmc: PMC6282292pubmed: 30518361
  21. Fulkerson E, Egol KA, Kubiak EN, Liporace F, Kummer FJ, Koval KJ. Fixation of diaphyseal fractures with a segmental defect: A biomechanical comparison of locked and conventional plating techniques. J Trauma 2006 Apr;60(4):830-5.
    pubmed: 16612304
  22. Gareb B, van Bakelen NB, Dijkstra PU, Vissink A, Bos RRM, van Minnen B. Efficacy and morbidity of biodegradable versus titanium osteosyntheses in orthognathic surgery: A systematic review with meta-analysis and trial sequential analysis. Eur J Oral Sci 2021 Oct;129(5):e12800.
    pmc: PMC8596673pubmed: 34131965
  23. Gibert S, Ragetly GR, Boudrieau RJ. Locking compression plate stabilization of 20 distal radial and ulnar fractures in toy and miniature breed dogs. Vet Comp Orthop Traumatol 2015;28(6):441-7.
    pubmed: 26423824
  24. Gieling F, Peters S, Erichsen C, Richards RG, Zeiter S, Moriarty TF. Bacterial osteomyelitis in veterinary orthopaedics: Pathophysiology, clinical presentation and advances in treatment across multiple species. Vet J 2019 Aug;250:44-54.
    pubmed: 31383419
  25. Gilde AK, Jones CB, Sietsema DL, Hoffmann MF. Does plate type influence the clinical outcomes and implant removal in midclavicular fractures fixed with 2.7-mm anteroinferior plates? A retrospective cohort study. J Orthop Surg Res 2014 Jul 4;9:55.
    pmc: PMC4104465pubmed: 24993508
  26. Gorter EA, Vos DI, Sier CF, Schipper IB. Implant removal associated complications in children with limb fractures due to trauma. Eur J Trauma Emerg Surg 2011 Dec;37(6):623-7.
    pmc: PMC3232347pubmed: 22207879
  27. Gosselin RA, Roberts I, Gillespie WJ. Antibiotics for preventing infection in open limb fractures. Cochrane Database Syst Rev 2004;2004(1):CD003764.
    pmc: PMC8728739pubmed: 14974035
  28. Grogan CH. Experimental studies in metal cancerigenesis. VIII. On the etiological factor in chromate cancer. Cancer 1957 May-Jun;10(3):625-38.
    pubmed: 13460959
  29. Guerrero TG, Kalchofner K, Scherrer N, Kircher P. The Advanced Locking Plate System (ALPS): A retrospective evaluation in 71 small animal patients. Vet Surg 2014 Feb;43(2):127-35.
    pubmed: 24393096
  30. Harrison JW, McLain DL, Hohn RB, Wilson GP 3rd, Chalman JA, MacGowan KN. Osteosarcoma associated with metallic implants. Report of two cases in dogs. Clin Orthop Relat Res 1976 May;(116):253-7.
    pubmed: 1064496
  31. Hudson CC, Pozzi A, Lewis DD. Minimally invasive plate osteosynthesis: Applications and techniques in dogs and cats.. Vet Comp Orthop Traumatol 2009;22(3):175-82.
    pubmed: 19448871
  32. Hulsmans MH, van Heijl M, Houwert RM, Hammacher ER, Meylaerts SA, Verhofstad MH, Dijkgraaf MG, Verleisdonk EJ. High irritation and removal rates after plate or nail fixation in patients with displaced midshaft clavicle fractures.. Clin Orthop Relat Res 2017 Feb;475(2):532-9.
    pmc: PMC5213945pubmed: 27830484
  33. Isaka M, Kokubo D, Sakai T. The occurrence of osteosarcoma after tibial fracture repair in a dog.. Open Vet J 2021 Jan-Mar;11(1):11-3.
    pmc: PMC8057204pubmed: 33898278
  34. Jain RK, Patel Y, Jayaswal A, Verma A. Indications for implant removal: A prospective study.. Int J Res Orthop 2019;5(2):253-9.
  35. Ketonis C, Parvizi J, Jones LC. Evolving strategies to prevent implant-associated infections.. J Am Acad Orthop Surg 2012 Jul;20(7):478-80.
    pubmed: 22751167
  36. Kettunen J, Kroger H, Bowditch M, Joukainen J, Suomalainen O. Bone mineral density after removal of rigid plates from forearm fractures: preliminary report.. J Orthop Sci 2003;8(6):772-6.
    pubmed: 14648263
  37. Khan MS, ur Rehman S, Ali MA, Sultan B, Sultan S. Infection in orthopedic implant surgery, its risk factors and outcome.. J Ayub Med Coll Abbottabad 2008 Jan-Mar;20(1):23-5.
    pubmed: 19024180
  38. Kirkpatrick CJ, Alves A, Kohler H, Kriegsmann J, Bittinger F, Otto M, Williams DF, Eloy R. Biomaterial-induced sarcoma: A novel model to study preneoplastic change.. Am J Pathol 2000 Apr;156(4):1455-67.
    pmc: PMC1876896pubmed: 10751369
  39. Langkamer VG, Ackroyd CE. Removal of forearm plates. A review of the complications.. J Bone Joint Surg Br 1990 Jul;72(4):601-4.
    pubmed: 2380210
  40. Loder RT, Feinberg JR. Orthopaedic implants in children: Survey results regarding routine removal by the pediatric and nonpediatric specialists.. J Pediatr Orthop 2006 Jul-Aug;26(4):510-9.
    pubmed: 16791071
  41. Marcellin-Little DJ, DeYoung DJ, Thrall DE, Merrill CL. Osteosarcoma at the site of bone infarction associated with total hip arthroplasty in a dog.. Vet Surg 1999 Jan-Feb;28(1):54-60.
    pubmed: 10025641
  42. Matsuura Y, Rokkaku T, Suzuki T, Thoreson AR, An KN, Kuniyoshi K. Evaluation of bone atrophy after treatment of forearm fracture using nonlinear finite element analysis: A comparative study of locking plates and conventional plates.. J Hand Surg Am 2017 Aug;42(8):659.e1-659.e9.
    pubmed: 28552442
  43. McDougall RA, Spector DI, Hart RC, Dycus DL, Erb HN. Timing of and risk factors for deep surgical site infection requiring implant removal following canine tibial plateau leveling osteotomy.. Vet Surg 2021 Jul;50(5):999-1008.
    pubmed: 33826172
  44. Melcher GA, Hauke C, Metzdorf A, Perren SM, Printzen G, Schlegel U, Ziegler WJ. Infection after intra-medullary nailing: An experimental investigation on rabbits.. Injury 1996;27(3):23-6.
    pubmed: 9039350
  45. Morshed S, Humphrey M, Corrales LA, Millett M, Hoffinger SA. Retention of flexible intramedullary nails following treatment of pediatric femur fractures.. Arch Orthop Trauma Surg 2007 Sep;127(7):509-14.
    pubmed: 17237933
  46. Muller-Farber J. Die Metallentfernung nach Osteosynthesen. Indikationen und Risiken [Metal removal after osteosyntheses. Indications and risks]. Orthopade 2003;32(11):1039-57, quiz 1058.
    pubmed: 15088628
  47. Muroi N, Ochi H, Shimada M, Asou Y, Hara Y. Effects of long-term plate fixation with different fixation modes on the radial cortical bone in dogs. PLoS One 2021 Feb 19;16(2):e0247410.
    pmc: PMC7895383pubmed: 33606794
  48. Murphy ST, Parker RB, Woodard JC. Osteosarcoma following total hip arthroplasty in a dog. J Small Anim Pract 1997 Jun;38(6):263-7.
    pubmed: 9200118
  49. Operskalski EA, Preston-Martin S, Henderson BE, Visscher BR. A case-control study of osteosarcoma in young persons. Am J Epidemiol 1987 Jul;126(1):118-26.
    pubmed: 3473934
  50. Pagel T. Mikrobielle Besiedlung von Implantaten nach Ostosynthesen bei Kleintieren: Inzidenz und Einflussfaktoren [Microbial colonization of implants after ostosynthesis in small animals: Incidence and influencing factors]. [dissertation]. [Berlin, Germany]: Freie Universität Berlin; 2015. p. 78-9.
  51. Piras A. Feline orthopaedics: Cats are not small dogs. WSAVA – Annual Congress 2009.
  52. Prediger B, Mathes T, Probst C, Pieper D. Elective removal vs. retaining of hardware after osteosynthesis in asymptomatic patients-a scoping review. Syst Rev 2020 Oct 2;9(1):225.
    pmc: PMC7532570pubmed: 33008477
  53. Raja S, Imbuldeniya AM, Garg S, Groom G. Difficulties encountered removing locked plates. Ann R Coll Surg Engl 2012 Oct;94(7):502-5.
    pmc: PMC3954247pubmed: 23031770
  54. Raney EM, Freccero DM, Dolan LA, Lighter DE, Fillman RR, Chambers HG. Evidence-based analysis of removal of orthopaedic implants in the pediatric population. J Pediatr Orthop 2008 Oct-Nov;28(7):701-4.
    pubmed: 18812893
  55. Reith G, Schmitz-Greven V, Hensel KO, Schneider MM, Tinschmann T, Bouillon B, Probst C. Metal implant removal: Benefits and drawbacks – A patient survey. BMC Surg 2015 Aug 7;15:96.
    pmc: PMC4528685pubmed: 26250649
  56. Richards RH, Palmer JD, Clarke NM. Observations on removal of metal implants. Injury 1992;23(1):25-8.
    pubmed: 1541494
  57. Richardson DW. Indications and technique for removal of implants after fracture healing. AOVET Course-Advances in Equine Fracture Management Davos, Switzerland; 2008.
  58. Rightmire E, Zurakowski D, Vrahas M. Acute infections after fracture repair: Management with hardware in place. Clin Orthop Relat Res 2008 Feb;466(2):466-72.
    pmc: PMC2505119pubmed: 18196433
  59. Roe SC, DeYoung D, Weinstock D, Kyles A. Osteosarcoma eight years after total hip arthroplasty. Vet Surg 1996 Jan-Feb;25(1):70-4.
    pubmed: 8719088
  60. Rose BW, Novo RE, Olson EJ. Osteosarcoma at the site of a triple pelvic osteotomy in a dog. J Am Anim Hosp Assoc 2005 Sep-Oct;41(5):327-31.
    pubmed: 16141185
  61. Rosson JW, Petley GW, Shearer JR. Bone structure after removal of internal fixation plates.. J Bone Joint Surg Br 1991a Jan;73(1):65-7.
    pubmed: 1991777
  62. Rosson J, Egan J, Shearer J, Monro P. Bone weakness after the removal of plates and screws. Cortical atrophy or screw holes?. J Bone Joint Surg Br 1991b Mar;73(2):283-6.
    pubmed: 2005156
  63. Rosson J, Murphy W, Tonge C, Shearer J. Healing of residual screw holes after plate removal.. Injury 1991c Sep;22(5):383-4.
    pubmed: 1806500
  64. Ruggles A. Implant removal in horses when and why.. AOVET Course-Advances in Equine Fracture Management Davos, Switzerland; 2013. p. 206-101.
  65. Sanderson PL, Ryan W, Turner PG. Complications of metalwork removal.. Injury 1992;23(1):29-30.
    pubmed: 1541495
  66. Savicky R, Beale B, Murtaugh R, Swiderski-Hazlett J, Unis M. Outcome following removal of TPLO implants with surgical site infection.. Vet Comp Orthop Traumatol 2013;26(4):260-5.
    pubmed: 23857570
  67. Schlegel U, Perren SM. Surgical aspects of infection involving osteosynthesis implants: Implant design and resistance to local infection.. Injury 2006 May;37(Suppl_2):S67-73.
    pubmed: 16651074
  68. Sinibaldi K, Rosen H, Liu SK, DeAngelis M. Tumor associated with metallic implants in animals.. Clin Orthop Relat Res 1976;118:257-66.
    pubmed: 182427
  69. Slunsky P, Brunnberg M, Brunnberg L, Pagel T. Post-traumatic osteomyelitis in dogs and cats and the comparison with the incidence of bacterial colonisation in removed plate implants.. Intern J Appl Res Vet Med 2017;15(1):31-3.
  70. Stewart S, Richardson D, Boston R, Schaer TP. Risk factors associated with survival to hospital discharge of 54 horses with fractures of the radius.. Vet Surg 2015 Nov;44(8):1036-41.
    pubmed: 26455917
  71. Tang N, Song WX, Luo J, Haydon RC, He TC. Osteosarcoma development and stem cell differentiation.. Clin Orthop Relat Res 2008 Sep;466(9):2114-30.
    pmc: PMC2492997pubmed: 18563507
  72. Thompson AM, Bergh MS, Wang C, Wells K. Tibial plateau levelling osteotomy implant removal: A retrospective analysis of 129 cases.. Vet Comp Orthop Traumatol 2011;24(6):450-6. Erratum in: Vet Comp Orthop Traumatol. 2012;25(2):171.
    pubmed: 21975493
  73. Townend M, Parker P. Metalwork removal in potential army recruits. Evidence-based changes to entry criteria.. J R Army Med Corps 2005 Mar;151(1):2-4.
    pubmed: 15912677
  74. Trampuz A, Widmer AF. Infections associated with orthopedic implants.. Curr Opin Infect Dis 2006 Aug;19(4):349-56.
    pubmed: 16804382
  75. Trampuz A, Zimmerli W. Diagnosis and treatment of infections associated with fracture-fixation devices.. Injury 2006 May;37(Suppl_2):59-66.
    pubmed: 16651073
  76. Vos D, Hanson B, Verhofstad M. Implant removal of osteosynthesis: The Dutch practice. Results of a survey.. J Trauma Manag Outcomes 2012 Aug 3;6(1):6.
    pmc: PMC3485133pubmed: 22863279
  77. Vos DI, Verhofstad MH. Indications for implant removal after fracture healing: A review of the literature.. Eur J Trauma Emerg Surg 2013 Aug;39(4):327-37.
    pubmed: 26815392
  78. Woltz S, Duijff JW, Hoogendoorn JM, Rhemrev SJ, Breederveld RS, Schipper IB, Beeres FJ. Reconstruction plates for midshaft clavicular fractures: A retrospective cohort study.. Orthop Traumatol Surg Res 2016 Feb;102(1):25-9.
    pubmed: 26768774

Citations

This article has been cited 3 times.
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  2. Candela Andrade M, Petereit F, Slunsky P, de Rus Aznar I, Brunnberg L. Healing of Comminuted Fractures of Long Bones in Dogs.. Animals (Basel) 2025 Feb 2;15(3).
    doi: 10.3390/ani15030413pubmed: 39943184google scholar: lookup
  3. Candela Andrade M, Slunsky P, Pagel T, De Rus Aznar I, Brunnberg M, Brunnberg L. Microbial Colonization of Explants after Osteosynthesis in Small Animals: Incidence and Influencing Factors.. Vet Sci 2024 May 16;11(5).
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