The innovation trap: modular neck in total hip arthroplasty

  • Samo Karel Fokter Univerzitetni klinični center MariborOddelek za ortopedijo
  • Vesna Levašič Ortopedska bolnišnica Valdoltra Ankaran
  • Simon Kovač Ortopedska bolnišnica Valdoltra Ankaran
Keywords: hip arthroplasty, modular neck failure, bimodular femoral stem, titanium-alloy, complications of arthroplasty, arthroplasty registries


Background: Innovations play the key role in the success of orthopaedic surgery. However, even minor modifications in the established concepts and proven designs may result in disasters. The endemic of modular femoral neck fracture (24 cases of about 4000 implanted) in fully modular total hip arthroplasty, popular in our country for the last 20 years, seems to challenge us with such an unfortunate consequences. The aim of this report was to analyze the extent and the causes of the problem on the one hand and to propose possible solutions on the other.

Methods: Literature search for problems associated with Profemur Z (or earlier versions with the same taper-cone design) fully-modular femoral stem made of titanium alloy (Ti6Al4V) was performed, and hip arthroplasty registries were searched to evaluate the failure rates of the mentioned design. Mechanisms of failure were studied to get in-depth understanding of this particular hip reconstruction device.

Results: Since 2010 onwards, several case reports on catastrophic modular femoral neck fractures of Profemur Z were published. Te frst Slovenian case was described in 2012. The first two larger series with modular femoral neck fractures were published in 2016. Te Australian Joint Replacement Registry was the first to discover increased revision rates due to fractures of this hip reconstruction system. Public Agency of the Republic of Slovenia for Medicinal Products and Medical Devices (JAZMP) received frst two reports regarding Profemur Z modular neck complication from abroad in 2010, the first Slovenian report was received in 2012, and altogether 7 reports from Slovenian hospitals were received until December 2016. Corrosion at the neck-taper interface, where two equal or different materials are subject to constant wear in the presence of body fluids, is assumed to be responsible for the unacceptable high failure rate.

Conclusions: Manufacturers are responsible to produce and market only safe devices. However, orthopaedic surgeons should carefully monitor any adverse effect of innovations. JAZMP took adequate measures only after having received an urgent field safety corrective notice from the manufacturer in 2015 indicating that all lots of long modular necks made from cobalt-chromium alloy should be withdrawn. Tis should be viewed in concordance with the fact that the regulatory agency of the Republic of Slovenia was not receiving vigilance reports accurately and was thus unaware of the extent of this complication. A national arthroplasty registry would probably warn orthopaedic community on this questionable innovation earlier. Regulatory bodies should therefore establish such a registry as soon as possible, for the benefit of our patients.


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Traina F, De Clerico M, Biondi F, Pilla F, Tassinari E, Toni A. Sex differences in hip morphology: is stem modularity effective for total hip replacement? J Bone Joint Surg Am. 2009;91 Suppl 6:121–8.

Archibeck MJ, CumminsT, Carothers J, Junick DW, White RE Jr. A comparison of two implant systems in restoration of hip geometry in arthroplasty. Clin Orthop Relat Res. 2011;469(2):443–6.

Massin P, Geais L, Astoin E, Simondi M, Lavaste F. Te anatomic basis for the concept of lateralized femoral stems: a frontal plane radiographic study of the proximal femur. J Arthroplasty. 2000;15(1):93–101.

Antonietti B, Paderni S, Sama D, Comitini V, Sudanese A. Anatomic cementless total hip arthroplasty with ceramic bearings and modular necks: 3 to 5 years follow-up. Chir Organi Mov. 2003;88(3):259–265.

Collier JP, Mayor MB, Williams IR, Surprenant VA, Surprenant HP, Currier BH. Te tradeoffs associated with modular hip prostheses. Clin Orthop Relat Res. 1995;(311):91–101.

Wright G, Sporer S, Urban R, Jacobs J. Fracture of a modular femoral neck after total hip arthroplasty: a case report. J Bone Joint Surg Am. 2010;92(6):1518–1521.

Vučajnik I, Fokter SK. Modular Femoral Neck Fracture afer Total Hip Arthroplasty. In: Fokter SK, ed. Recent Advances in Hip and Knee Arthroplasty. Rijeka: InTech; 2012;11:169–80 [cited 2016 aug 20]. Available from:

Australian Orthopaedic Association National Joint Replacement Registry. Annual Report 2013 [cited 2016 aug 29]. Available from:

Levašič V, Milošev I. Register artroplastike Ortopedske bolnišnice Valdoltra. [cited 2016 aug 27]. Available from:

Manufacturer and user facility device experience database (MAUDE). United States Food and Drug Administration [cited 2016 aug 29]. Available from:

Atwood SA, Patten EW, Bozic KJ, Pruitt LA, Ries MD. Corrosion-induced fracture of a double-modular hip prosthesis: a case report. J Bone Joint Surg Am. 2010;92(6):1522–1525.

Wilson DAJ, Dunbar MJ, Amirault JD, Farhat Z. Early failure of a modular femoral neck total hip arthroplasty component: a case report. J Bone Joint Surg Am. 2010;92(6):1514–1517.

Dangles CJ, Altstetter CJ. Failure of the modular neck in a total hip arthroplasty. J Arthroplasty. 2010;25(7):1169.e5-e7.

Skendzel JG, Blaha JD, Urquhart AG. Total hip arthroplasty modular neck failure. J Arthroplasty. 2011;26(2):338.e1-e4.

Ellman MB, Levine BR. Fracture of the modular femoral neck component in total hip arthroplasty. J Arthroplasty. 2013;28(1):196.e1-e5.

Fokter SK, Rudolf R, Molicnik A. Titanium alloy femoral neck fracture-clinical and metallurgical analysis in 6 cases. Acta Orthop. 2016;87(2):197–202.

Pour AE, Borden R, Murayama T, Groll-Brown M, Blaha JD. High risk of failure with bimodular femoral components in THA. Clin Orthop Relat Res. 2016;474(1):146–53.

Levašič V, Kovač S. Naše izkušnje s Profemur Z modularnim femoralnim deblom deblom. In: 4. raziskovalni dan Ortopedske bolnišnice Valdoltra; 30.maja 2014; Ankaran, Slovenija. Ankaran: Ortopedska bolnišnica Valdoltra; 2014.

Grupp TM, Weik T, Bloemer W, Knaebel H-P. Modular titanium alloy neck adapter failures in hip replacement-failure mode analysis and influence of implant material. BMC Musculoskelet Disord. 2010;11:3.

Sotereanos NG, Sauber TJ, Tupis TT. Modular femoral neck fracture after total hip arthroplasty. J Arthroplasty. 2013;28(1):196.e7-e9.

Molloy DO, Munir S, Jack CM, Cross MB, Walter WL, Walter WK Sr. Fretting and corrosion in modular-neck total hip arthroplasty femoral stems. J Bone Joint Surg Am. 2014;96(6):488–93.

Bernstein DT, Mefah M, Paranilam J, Incavo SJ. Eighty-six percent failure rate of a modular-neck femoral stem design at 3 to 5 years. J Bone Joint Surg Am. 2016;98:e49(1–7).

Mencière ML, Amouyel T, Taviaux J, Bayle M, Laterza C, Mertl P. Fracture of the cobalt-chromium modular femoral neck component in total hip arthroplasty. Orthop Traumatol Surg Res. 2014;100(5):565–8.

Fokter SK, Moličnik A, Kavalar R, Pelicon P, Rudolf R, Gubeljak N. Why do some titanium-alloy total hip arthroplasty modular necks fail? J Mech Behav Biomed Mater. 2016;69:107–114.

Reito A, Eskelinen A, Pajamäki J, Puolakka T. Neck fracture of the Exeter stem in 3 patients: A cause for concern? Acta Orthop. 2016;87(2):193–196.

Labek G. EAR Handbook for Register Development. 2009 [cited 26. 1 2016]. Available from:

Gray BH, et al. Registries as a Knowledge-Development Tool: Te Experience of Sweden and England 2013 [cited 30. 8. 2016]. Available from:

Mavčič B. Potrebe po endoprotezah kolka in kolena v Sloveniji do leta 2050. Med Razgl. 2016;55(1):5–12.

How to Cite
Fokter S, Levašič V, Kovač S. The innovation trap: modular neck in total hip arthroplasty. ZdravVestn [Internet]. 15Apr.2017 [cited 19Oct.2019];86(3-4):115-26. Available from: