Background Dual-mobility (DM) cups were introduced to minimize the risk of THA dislocation. The overall rate of dislocation of DM cups (including both large and small articulations) is controversial and ranges from 0% to 5% in previous studies. Questions/purposes We therefore recorded (1) the dislocation rate, (2) loosening and osteolysis, and (3) subsequent related revisions with DM cups. Methods Between 1998 and 2003, 2480 primary THAs with DM cups were undertaken in 2179 patients. The mean age was 69 years (range, 19-94 years). This group underwent specific clinical and radiographic evaluation at a minimum followup of 0.17 years (mean, 7 years; range, 0.17-11 years) to assess dislocation, reoperation, osteolysis, and cup fixation.Results There were 22 dislocations (0.88%): 15 dislocations of large articulations (0.6%), with two (0.08%) recurring but only one requiring revision (0.04%), and seven intraprosthetic small articulation dislocations (0.28%), all needing revision surgery. At last followup, mean Harris hip score was 91 (range, 60-100); 2439 cups (98%) showed no signs of loosening; and 141 patients (145 hips) had osteolysis (6%). Osteolysis and cup loosening were more frequent in patients younger than 50 years at the time of surgery. The 10-year survivorship considering revision for any reason was 93% (95% CI, 91%-95%). Conclusions DM cups had a low dislocation rate in primary THA, with a limited frequency of adverse effects. We recommend DM cups to minimize dislocation in populations at high risk for instability, but they should be avoided in younger, active patients at higher risk for osteolysis.

Posterior reversible encephalopathy syndrome (PRES) associates various neurological manifestations (headaches, seizures, altered mental status, cortical blindness, focal neurological deficits, vomiting) and transient changes on neuroimaging consistent with cerebral edema. Posterior reversible encephalopathy syndrome mainly occurs in the setting of hypertension, eclampsia, renal failure and/or use of immunosuppressive drugs. We report four cases of PRES complicating systemic lupus erythematosus (SLE). In all our cases, renal involvement and hypertension were present. Neurological symptoms were typical. Magnetic resonance imaging showed posterior cerebral edema and in one case hemorrhagic complication. With symptomatic treatment and immunosuppressor withdrawal when they were previously used, symptoms fully resolved within 15 days in all cases, but one who had only partial regression related to cerebral hemorrhage. Including our cases, we reviewed a total of 46 patients with SLE and PRES. Their clinical and radiological presentation was not specific. The peculiar role of SLE itself in the occurrence of PRES was not clear, since hypertension (95%), renal involvement (91%), recent onset of immunosuppressive drugs (54%) and/or recent treatment with high intravenous dose of steroids (43%) were often present. The hypertension and other worsening factors should be treated. Finally, the evolution of this clinical and radiological spectacular syndrome is generally rapidly favorable.

Level III; case-control study.

BackgroundDual mobility (DM) cups of mobile polyethylene were introduced to prevent total hip arthroplasty (THA) dislocation, but no large series with this design to treat recurrent instability have been reported.PurposeOur retrospective investigation ascertained the efficiency of DM cups in correction of recurrent dislocation and assessed any adverse effects.MethodsOne hundred eighty THAs with recurrent instability were revised to DM cups in 180 patients (mean age, 67.4 ± 11.7 years; range, 19 to 92 years). Thirty-one patients (17.2%) underwent at least one earlier THA revision, and 15 (10.3%) incurred non-union of the greater trochanter. Of the initial group in 2009, 145 patients had completed evaluations which included assessment of the Harris Hip Score and a radiographic assessment at a mean follow-up of 7.7 ± 2.2 years (range, 4 to 14 years). The rate of survival was calculated considering any reason for revision as failure.ResultsAt follow-up, Harris hip score was 83.9 ± 16.1 (range, 21 to 100). Dislocation of the large articulation occurred in seven hips (4.8%), and only two recurred (1.4%) (one requiring additional revision). In addition, two intra-prosthetic dislocations of the small articulation (1.4%) were observed and needed revision surgery. The large number of earlier surgeries and non-union of the greater trochanter were related to recurrent instability. Two cups (1.4%) showed signs of definite loosening; six (4.1%) presented signs of possible loosening. Twenty-nine hips manifested femoral or acetabular osteolysis (20%), but only three were severe. Eight-year survival rate considering revision for any reason was 92.6% (95% CI, 85.5–96.4%).ConclusionsThis series indicates that DM cups are a viable option to treat recurrent THA instability. Their design provides a low risk of recurrent instability without increasing mechanical complications.