Fig. 1 Coronal short tau inversion recovery (STIR) magnetic resonance image acquired with use of metal artifact reduction sequence (MARS), demonstrating a large pseudotumor (arrows) surrounding the prosthetic hip joint, approximately twenty-one months following total hip arthroplasty (Case 3). As a reference, the greater trochanter (GT), modular prosthetic femoral neck (N), and modular femoral head (H) are labeled.

The CONSORT (Consolidated Standards of Reporting Trials) diagram. ICBG = iliac crest bone graft.

Coronal fast-spin-echo images of the right (A) and left (C) hips in an asymptomatic subject who underwent bilateral metal-on-metal hip resurfacing arthroplasty. Note the susceptibility artefact generated by the cobalt-chromium prostheses, which obscures visualization of the synovium. On the MAVRIC SL image of the right hip (B), synovitis is evident with fluid-signal-intensity expansion of the pseudocapsule (black arrows). On the MAVRIC SL image of the left hip (D), there is no synovitis and the pseudocapsule (white arrows) is closely applied to the femoral neck.

Risk of common peroneal nerve palsy according to BMI. The error bars indicate the 95% CI.

Diagram illustrating setup of the apparatus for controlling pelvic rotation and tilt. An enclosure was constructed for the cadaveric pelvis to facilitate precise rotation and tilting. This comprised a box with a position-pointing device and three wooden wedges to allow accurate rotation and tilting of the flat baseboard by ±5°, ±10°, and ±15°. Relevant anatomical landmarks such as the vertebral body of S1 and the anterior superior iliac spines were left prominently displayed outside the foam fixation. These landmarks were subsequently used to center the x-ray beam on the pelvis.

An XY scatterplot of blood cobalt levels versus acetabular cup wear rate.

Fig. 1-A In a normal hip, the fovea capitis femoris is caudal to the weight-bearing area of the acetabulum. Fig. 1-B In dysplastic hips, because of the extreme valgus, the fovea can extend into the weight-bearing area, reducing the loaded articular cartilage surface. The fovea-acetabular angle is defined as the angle formed by a line from the femoral head center to the medial edge of the weight-bearing zone of the acetabulum (reference line) and a line from the femoral head center to the superior edge of the fovea capitis femoris. The value of the fovea-acetabular angle is positive if the superior edge of the fovea capitis femoris lies caudal to the medial edge of the weight-bearing zone of the acetabulum (Fig. 1-A). It becomes negative if the superior edge of the fovea capitis femoris lies cranial to the medial edge of the weight-bearing zone of the acetabulum (Fig. 1-B).

Serum cobalt concentrations. Line graph showing the concentrations of cobalt in the serum, in nanograms per milliliter (ng/mL, parts per billion), as a function of time in the four groups investigated. The hybrid group had cobalt levels that were 3.2 times higher at 120 months than they were at baseline and had cobalt concentrations that were significantly higher than the levels in the titanium (Ti) group at thirty-six, sixty, eighty-four, ninety-six, and 120 months (p < 0.01). *Cobalt levels in the hybrid group were significantly different than those in the titanium group (p < 0.05).

Kaplan-Meier survival curve with failure defined as cup revision for aseptic loosening or definite radiographic loosening.

Fifteen-year survivorship curve for the low-carbide metal-on-metal Zweymüller-Plus total hip arthroplasty system, according to the Kaplan-Meier method, with revision of any component for any reason used as the end point, including hips with a pending revision. The upper and lower curves represent the 95% CI.