Dual Mobility for Monoblock Metal-on-Metal Revision-Is It Safe?

BACKGROUND: Revision of monoblock metal-on-metal (MoM) total hip arthroplasty (THA) is associated with high complication rates. Limited revision by conversion to a dual mobility (DM) without acetabular component extraction may mitigate these complications. However, the concern for polyethylene wear and osteolysis remains unsettled. This study investigates the results of DM conversion of monoblock MoM THA compared to formal acetabular revision. METHODS: One hundred forty-three revisions of monoblock MoM THA were reviewed. Twenty-nine were revisions to a DM construct, and 114 were complete revisions of the acetabular component. Mean patient age was 61, 54% were women. Components used, acetabular cup position, radiographic outcomes, serum metal ion levels, and HOOS Jr clinical outcome scores were investigated. RESULTS: At 3.9 years of follow-up (range 2-5), there were 2 revisions (6.9%) in the DM cohort, 1 for instability and another for periprosthetic fracture. Among the formal acetabular revision group there was a 20% major complication rate (23/114) and 16% underwent revision surgery (18/114) for aseptic loosening of the acetabular component (6%), deep infection (6%), dislocation (4%), acetabular fracture (3%), or delayed wound healing (6%). In the DM cohort, there were no radiographic signs of aseptic loosening, component migration, or polyethylene wear. One DM patient had a small posterior metadiaphyseal femur lesion that will require close monitoring. There were no other radiographic signs of osteolysis. There were no clinically significant elevations of serum metal ion levels. HOOS Jr scores were favorable. CONCLUSION: Limited revision with conversion to DM is a viable treatment option for failed monoblock MoM THA with lower complication rates than formal revision. Limited revision to DM appears to be a safe option for revision of monoblock MoM THA with a cup in good position and an internal geometry free of sharp edges or articular surface damage. Longer follow-up is needed to demonstrate any potential wear implications of these articulations.

Arthroscopic Capsulolabral Reconstruction for Posterior Shoulder Instability in Patients 18 Years Old or Younger.

PURPOSE: The purpose of this study was to determine clinical outcomes for pain, function, instability, and return to activity level and sport in patients 18 years old or younger, treated with arthroscopic capsulolabral reconstruction for posterior instability of the shoulder. METHODS: We retrospectively reviewed 22 athletes (25 shoulders) with unidirectional recurrent posterior shoulder instability treated with arthroscopic posterior capsulolabral reconstruction from 2002 to 2009. The study group included 19 males and 3 females with a mean age of 17 years. Patients were evaluated at a mean of 63 months postoperatively with American Shoulder and Elbow Surgeons (ASES) composite scores and subset scores for pain, stability, and function, as well as Marx activity scores. Statistical analysis was performed for continuous and categorical variables with significance set at α=0.05. RESULTS: The overall mean postoperative ASES and Marx scores were 74.3 (SD±20) and 14.8 (SD±3.2), respectively. Twenty-three shoulders were stable at the time of final follow-up (92%). Two shoulders had traumatic recurrent episodes of posterior instability. Return to sport at the same level was achieved in 67% of athletes. Overall postoperative ASES scores were significantly higher in male patients (P=0.04), those with traumatic injuries (P=0.03), and in contact athletes (P<0.01). Postoperative Marx scores were significantly higher in male patients (P<0.01). Preoperative and postoperative range of motion were assessed and without significant difference. CONCLUSION: Arthroscopic capsulolabral reconstruction is an effective treatment for symptomatic unidirectional posterior glenohumeral instability in 18 years old or younger. In distinction to treatment of anterior instability, outcomes in this series were improved in males, contact athletes, and patients with a traumatic etiology of posterior glenohumeral instability. LEVEL OF EVIDENCE: Level IV.