Dual-taper modular hip implant: Investigation of 3-dimensional surface scans for component contact, shape, and fit

Frisch, Nicholas B.; Lynch, Jonathan R.; Pourzal, Robin; Banglmaier, Richard F.; Silverton, Craig D.

doi:10.1016/j.artd.2018.06.001

Cited by 3 publications

(5 citation statements)

References 28 publications

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“…In in vitro conditions, artificially contaminated taper junctions with porcine bone chips have created micromotions that are more than twice as large than those of clean taper junctions [ 92 ]. Some relative motion at the neck-stem junction occurs due to the shape of the tapers deviating from an ideal design dimension [ 93 ]. Three-dimensional contact colour maps clearly indicate that the surfaces are not in contact over the entire circumstances but typically at four localized lines of contact.…”

Section: Discussionmentioning

confidence: 99%

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Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

2021

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Titanium (Ti) alloys have been proven to be one of the most suitable materials for orthopaedic implants. Dual modular stems have been introduced to primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. This systematic review highlights information acquired for dual modular Ti stem complications published in the last 12 years and offers a conclusive discussion of the gathered knowledge. Articles referring to dual modular stem usage, survivorship, and complications in English were searched from 2009 to the present day. A qualitative synthesis of literature was carried out, excluding articles referring solely to other types of junctions or problems with cobalt-chromium alloys in detail. In total, 515 records were identified through database searching and 78 journal articles or conference proceedings were found. The reasons for a modular neck fracture of a Ti alloy are multifactorial. Even though dual modular stems have not shown any clinical benefits for patients and have been associated with worse results regarding durability than monolithic stems, some designs are still marketed worldwide. Orthopaedic surgeons should use Ti6Al4V dual modular stem designs for primary THA in special cases only.

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Section: Discussionmentioning

confidence: 99%

“…Some implants also show one surface in contact or at closer proximity than the contralateral surface. The cause of the deviation in dimensions is most probably machine tool deflexion during machining [ 93 ].…”

Section: Discussionmentioning

confidence: 99%

Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

2021

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“…The cause of corrosion in the neck-stem junction has been debated. Some say that the shape of the neck-stem tapers may deviate from ideal dimensions causing relative motions between the neck and stem (Frisch et al 2018). Others state that corrosion occurs regardless of design and that the primary cause is mixed-metal couples with unequal modulus of elasticity (Young's modulus), allowing for increased metal transfer and surface damage (galvanic mode of corrosion) (Su et al 2017).…”

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confidence: 99%

Unexpected varus deformity and concomitant metal ion release and MRI findings of modular-neck hip stems: descriptive RSA study in 75 hips with 8 years’ follow-up

et al. 2020

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Background and purpose — Modular-neck hip stems have been identified with corrosion-related problems from the neck–stem junction. We report an ongoing varus deformity of modular-neck hip stems with simultaneous metal ion release observed during a study comparing the migration of modular vs. standard hip stems. Patients and methods — We followed 50 patients with modular and 25 with standard neck stems using radiostereometry (RSA). At 5-year follow-up, we noted a compromised integrity of the modular stem with varus deformity in the neck–stem interface. Changes in head–tip distance as well as whole-blood ion concentration and MRI findings were analyzed. The modular stems were followed further up to 8 years. Results — The head–tip distance decreased continuously by 0.15 mm per year resulting in 1.2 (95% CI 1.0–1.4) mm at 8 years for modular stems, while for the standard stems at 5 years, the decrease was 0.09 (CI 0.0–0.2) mm or 0.02 mm/year. For the modular stems, the reduction in head–tip distance correlated to the increase in whole-blood cobalt concentration at 8 years but not to the MRI grading of tissue reactions. At 5 years, cobalt levels were 4.9 µg/L for modular stems and at 8 years 4.8 µg/L, whereas for standard stems this was 1.0 µg/L. After 8 years, 9 of 72 stems had been revised for different reasons, but only 1 with obvious adverse local tissue reaction (ALTR). Interpretation — We present a surprisingly large progressive deformation at the modular neck–stem junction, but so far without a definite clinical problem. Even the femoral head seems to show slight compression onto the taper over time. A high rate of revisions for the modular type of this stem has raised general concerns, and it has been recalled from the market.

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“…Even though the authors have found the overall mean revision rate (3.95%) and the mean revision rate for fracture of the modular neck component (0.43%) for modular prosthesis acceptable, they consider modular prostheses to be a viable management option only in patients with considerable anatomical hip deformities that cannot be corrected with standard fixed-neck implants. The review also points out two national registry reports, which revealed that modular neck prostheses had a higher revision rate compared to traditional, fixed-neck prostheses in patients with osteoarthritis [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

“…Together with slight variation between implant position and offset, these dissimilarities could be responsible for different timing at which modular neck fracture occurred. However, Frisch et al have shown that the shape of the neck and stem tapers deviate from ideal design dimensions, contributing to relative motions between the neck and the stem and may place the implants at higher risk for failure [ 24 ]. This means that such catastrophic failures can occur unpredictively in otherwise normally functioning implant(s).…”

Section: Discussionmentioning

confidence: 99%

Bilateral neck fracture in bimodular femoral stem after primary total hip arthroplasty: a case report

Fokter

Gubeljak

Predan

et al. 2021

BMC Musculoskelet Disord

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Background Bi-modular stems were introduced in primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. Despite numerous reports on modular femoral neck fractures, some designs are still marketed worldwide. While the risk factors for the sudden failure are multifactorial and mostly known, the timing of this new THA complication is not predictable by any means. Case presentation In this report, the literature regarding one of the most popular bi-modular stems with specific neck-stem coupling (oval Morse taper) is reviewed and illustrated with a case of bilateral modular neck fracture in a patient with idiopathic aseptic necrosis of femoral heads treated with primary bi-modular THA. Because of bilateral modular femoral neck fracture, which occurred 3 years on the left side and 20 years after implantation on the right side, the patient required a total of 6 revisions and 208 days of hospitalized care. Conclusion To our knowledge, this is the first report of bilateral modular neck fracture in a single patient. Even though the same surgeon performed both operations and used the same neck length and orientation, fractures occurred with a 17-year time difference after implantation. This shows that we cannot predict with certainty when a fracture might occur. Orthopaedic surgeons should use bi-modular stem designs for primary THA very cautiously.

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Dual-taper modular hip implant: Investigation of 3-dimensional surface scans for component contact, shape, and fit

Cited by 3 publications

References 28 publications

Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

Unexpected varus deformity and concomitant metal ion release and MRI findings of modular-neck hip stems: descriptive RSA study in 75 hips with 8 years’ follow-up

Bilateral neck fracture in bimodular femoral stem after primary total hip arthroplasty: a case report

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