Implant fracture of modular revision stems is a major complication after total hip arthroplasty revision (rTHA). Studies looking at specific modular designs report fracture rates of 0.3% to 0.66% whereas fractures of monobloc designs are only reported anecdotally. It is unclear whether the overall re-revision rate of modular designs is higher and if, whether stem fractures or other revision reasons are responsible for this elevation.

All revisions within 5 years after implantation of a revision stems (n₀=13,900; n₅=2506) were analysed using Cox regression with design (modular: n=17, monobloc: n=27), BMI, Sex and Elixhauser Score as independent variables. One stage and two stage revisions were analysed separately (1-stage: modular n= 7,102; monobloc n= 4,542; 2-stage: 1,551 / 704). The revision volume of the hospitals was also considered (low: <20 revisions, medium: 21–50 revisions, high: >50 revisions).

For the 1-stage revisions, the re-revision risk after 4 years was 14,3% [13.2%, 15.5%] for monobloc and 17.4% [16.40%, 18.40%] for modular stems (p< 0.001). Stem fracture was the reason for re-revision in 2.4% of the modular (fracture rate 0.42%) and 0.6% of the monobloc revisions. The difference in re-revision rates between the designs was mainly due to differences in dislocation and stem loosening. For the 2-stage revisions, the revision risks for either design were similar (21.7% [18,5%, 25.4%] vs. 23.0% [20.8%, 25.4%]; p=0.05). Patient characteristics influenced the comparison between the two designs in the 1-stage group but very little in the 2-stage group.

Modular revision stem fractures only contribute very minor to re-revision risk. In 2-stage revisions, no difference in overall re-revision rates between designs was observed. This might indicate that the differences observed for 1-stage procedures are due to differences between the patient cohorts, not reflected by the parameters available or surgeon choice.

Aims

Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors.

Recent case reports have described V40 taper failure with clinically relevant adverse reaction to metal debris (ARMD). The real incidence of V40 taper damage and potential consequences are currently unclear, however. Aim of this study is therefore, to evaluate the long-term incidence of pseudotumors in a consecutive series of THA with V40 taper and identify potential influencing factors.

From 2006 to 2007 a total number of 120 patients (127 hips) received either an uncemented (Accolade©) or cemented hip stem (ABGII©), both with V40 taper (Stryker© Mahwah, New Jersey, USA). They all were combined with 36 mm Vitallium (CoCrMo) heads and uncemented cups (Trident©) with XLPE inlays. 11,2 +/− 0,5 years post-op 82 patients with 87 hips (mean age 74 years, 58 % female) underwent clinical (PROMs) and radiographic evaluation. In 71 patients (75 hips) MARS- MRI of the hip was performed. 38 patients were lost to follow-up. In 81 patients (86 hips) chrome and cobalt levels were determined.

MRI-investigation revealed 20 pseudotumors (26%) and 18 of them had a diameter of >2cm. Patients with pseudotumors had significant higher median cobalt ion levels compared to those without (2,85 μg/l vs. 1,32 μg/l; p=0,022) and a significant correlation between pseudotumors and cobalt levels was found. Radiographic osteolysis was associated with pseudotumors as well (p= 0,014). Neither approach, BMI, gender, age, type of stem, head length, inclination nor heterotope ossification showed a significant correlation to pseudotumor occurrence.

Due to the high incidence of local ARMD in in asymptomatic patients with V40 taper and metal heads we recommend regular post-operative follow-up investigations including routine metal ion screening and consecutive MRI investigation upon elevation.

Due to well-known complications of metal-on-metal hip resurfacing arthroplasty the indication for this procedure has significantly decreased over the past years. As a high number of patients is currently living with resurfacing implants, however, there is a clear need for information about the longterm results and especially about the rate of local as well as systemic adverse effects.

We retrospectively reviewed our first 95 patients who had 100 consecutive BHR hip resurfacings performed from 1998–2001. Median age at surgery was 52 years (range, 28–69 years); 49% were men. After a mean follow-up period of 16.1 years (range 15.2 – 17.6 years) we assessed survival rate (revision for any reason as endpoint), radiographic changes and patient-related outcome in patients who had not undergone revision. In addition we measured whole blood concentrations of cobalt at follow-up.

17% of our patients in the original cohort were lost to follow-up. In the remaining patients the 16-year survivorship was 80.1%. The overall survival rate was slightly higher in males (80.6%) than in females (77.1%). The WOMAC overall score showed a median value of 91.7 points (range 35.4 – 100). Median whole blood ion levels were 1.9 µg/L for cobalt (0.6 – 140.2 µg/L), 14.9% of patients showed elevated levels. The number of patients with relevant radiographic signs of local adverse reactions to metal debris was relatively low.

In contrast to earlier reports and very few other longterm studies our results show an unsatisfactory performance of resurfacing. In particular the outcome of male patients deteriorated between 10 and 16 years of follow-up. Although only a small number of patients shows relevant elevation of metal-ion levels, the clinical relevance has still to be determined.