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Case Reports: N. K. Bowman, T. A. Bucher, and A. A. Bassily Fracture of the stem of the femoral component after resurfacing arthroplasty of the hip J Bone Joint Surg Br 2006; 88-B: 1652-1653 [Abstract] [Full text] [PDF]

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Problems dealing with the central stem in hip resurfacing arthroplasty

Andrea E Salvi   (17 January 2008)

Hardware failure due to bone fracture of the femoral neck

Lukas A Lisowski   (26 January 2007)

Radiological findings associated with hip resurfacing

Paul E. Beaule   (22 December 2006)

Problems dealing with the central stem in hip resurfacing arthroplasty 17 January 2008
Andrea E Salvi, Assistant MD Mellino Mellini Hospital Trust, Civil Hospital of Iseo (Brescia, Italy), Orthopaedics Department Send letter to journal: Re: Problems dealing with the central stem in hip resurfacing arthroplasty andrea{at}orthopaedics.com Andrea E Salvi	Sir, I read this article with great interest and was not at all surprised at the findings. The original resurfacing arthroplasty of Professor Heinz Wagner was stemless,1 as was that of Patrinieri and Trentani.2 Concerning the Wagner version, one factor that may be responsible for the increased failure rate is the high susceptibility to avascular necrosis of the femoral head3 that causes a collapse of the femoral neck and the cup. Concerning the Patrinieri and Trentani version, when the need for revision occurred because of loosening, the stump of both femoral neck and head was significantly reduced in size,4 suggesting resorption caused by the cement and the metal of the prosthesis. The analysis on these prosthetic versions shows that failures were encountered even in resurfacing stemless models. The latest hip resurfacing versions have a central stem that serves to introduce the prosthetic head into a pre-drilled hole in the femoral neck in order to locate it to the anatomically correct position. I feel that this stem is quite dangerous, as it may make things worse. In this article the authors rightly affirm that the central stem is not designed to be load-bearing. In my opinion surgical errors may jeopardise the outcome. The central stem may start to bear weight when the bony channel for the stem is made slightly inclined, as the stem can sometimes lie in a strictly adjacent channel allowing it to move up and down during ambulation, leading to a possible “fatigue” fracture of the neck as well as of the stem. Moreover, when the channel is made at the wrong angle, as the cup follows the stem during its insertion, the femoral neck will be notched leading to a neck or stem fracture. Besides surgical errors, in my opinion two additional 'dangerous' features of the resurfacing cups are worthy of note. Firstly, as the stem is made of metal, it can cause bone resorption, leading to a more fragile neck, allowing the stem to oscillate and break. Secondly, even though the bony channel for the central stem should be drilled perfectly, as it removes a certain quantity of bone, it can weaken the bony structure of the neck, leading to a possible fracture. A.E. Salvi, Assistant MD, Mellino Mellini Hospital Trust, Civil Hospital of Iseo, Brescia, Italy. 1. Wagner H. Surface replacement arthroplasty of the hip. Clin Orthop Relat Res 1978;134:102-30. 2. Trentani C, Vaccarino F. The Paltrinieri-Trentani hip joint resurface arthroplasty. Clin Orthop Relat Res 1978;134:36-40. 3. Head WC. Wagner surface replacement arthroplasty of the hip. Analysis of fourteen failures in forty-one hips. J Bone Joint Surg [Am] 1981;63-A:420-7. 4. Trentani C, Vaccarino F. Complications in surface replacement arthroplasty of the hip: experience with the Paltrinieri-Trentani prosthesis. Int Orthop 1981;4:247-52.
Hardware failure due to bone fracture of the femoral neck 26 January 2007
Lukas A Lisowski, Resident Orthopaedic Surgeon Slotervaart Hospital Amsterdam, The Netherlands Send letter to journal: Re: Hardware failure due to bone fracture of the femoral neck lisowski{at}lycos.nl Lukas A Lisowski	Sir, I read this case report and the online letter by Professor Beaulé with great interest. I found it very interesting that the varus positioning of the femoral head may have been due to migration because of avascular necrosis (AVN). However, this varus malalignment could be due to a fracture of the femoral neck. Although no macroscopic signs of bone fracture were seen during surgery, in my opinion microscopic evidence of a healed fracture could be present. I would say that that the varus malpositioning at three years follow-up would probably be due to a fracture of the femoral neck causing a fatigue failure of the hardware. L.A. Lisowski, Resident Orthopaedic Surgeon, Slotervaart Hospital, Amsterdam, The Netherlands.
Radiological findings associated with hip resurfacing 22 December 2006
Paul E. Beaule, Associate Professor University of Ottawa Send letter to journal: Re: Radiological findings associated with hip resurfacing pbeaule{at}ottawahospital.on.ca Paul E. Beaule	Sir, I read this case report with interest. First and foremost, this is not the first reported case. Such a case was reported by Gabriel and Trousdale1 after hemiresurfacing for osteonecrosis and later on, by Stem and associates.2 In both case reports the authors found that the femoral component did not have sufficient femoral head bone stock to support the implant leading to the majority of the load borne by the stem. More importantly, this case report illustrates the importance of better definition of the different radiological changes which can be associated with hip resurfacing and their significance. Consequently, I would argue that this femoral component had already failed at the two and a half year follow-up, since >1 mm radiolucencies are apparent on the radiograph. This is supported by our studies using The Ein Bild Roentgen Analyse-femoral component analysis (EBRA-FCA) method3,4 where stem lucencies are consistent and implant instability/migration lead to failure. The stem fracture represents another sign of loosening of the femoral implant. Finally, are the authors implying that fracture of the stem is in itself a mechanism of failure for hip resurfacing? Again, a critical analysis of the orientation of the femoral component shows relative varus which is known to lead to early failure.5,6 A comparison between the immediate post-operative radiograph and one at two and a half years could also show us if this varus positioning is a result of migration or not. P.E. Beaulé MD, FRCSC, Associate Professor, University of Ottawa, Ottawa, Canada. 1. Gabriel JL, Trousdale RT. Stem fracture after hemiresurfacing for femoral head osteonecrosis. J Arthroplasty 2003;18:96-99. 2. Stem E, Duffy G, Blaser K, O'Connor MI. Stem fracture of conserve hemiarthroplasty. J Arthroplasty 2004;19:923-26. 3. Beaule PE, Krismer M, Mayrhofer P, et al. EBRA-FCA for measurement of migration of the femoral component in surface arthroplasty of the hip. J Bone Joint Surg [Br] 2005;87-B:741-44. 4. Fowble VA, Schuc A, Hoke R, Bitsch R, Beaule PE. Clinical correlation of femoral component migration in hip resurafacing arthroplasty analyzed by Einzel-Bild-Rontgen-analyze-femoral component analysis. Orthop Clin North Am 2005;36:243-50. 5. Beaule PE, Lee J, LeDuff M, et al. Orientation of the femoral component in surface arthroplasty of the hip. A biomechanical and clinical analysis. J Bone Joint Surg [Am] 2004;86-A:2015-21. 6. Shimmin A, Back D. Femoral neck fractures following Birmingham hip resurfacing. A national review of 50 cases. J Bone Joint Surg [Br] 2005;87-B:463-64.