Geometric View of Measurement Errors

The slope of the best fit line from minimizing the sum of the squared oblique errors is the root of a polynomial of degree four. This geometric view of measurement errors is used to give insight into the performance of various slope estimators for the measurement error model including an adjusted fourth moment estimator introduced by Gillard and Iles (2005) to remove the jump discontinuity in the estimator of Copas (1972). The polynomial of degree four is associated with a minimun deviation estimator. A simulation study compares these estimators showing improvement in bias and mean squared error

Shoulder arthroplasty in the setting of previous stabilization surgery: a systematic review of matched case control studies at minimum 2 years follow-up

Background: Anterior shoulder instability causes considerable patient morbidity and the volume of shoulder stabilization surgery being performed annually is rising. Despite stabilization surgery, instability arthropathy in the long-term may arise requiring consideration of shoulder arthroplasty. This study evaluated the outcomes of shoulder arthroplasty following previous stabilization surgery with their associated changes in bony anatomy or soft tissue structure. Methods: A systematic review was performed as per Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines to identify all studies reporting outcomes of shoulder arthroplasty in the setting of previous stabilization surgery. Studies of >10 patients with a minimum of 24 months follow-up were included. Results: Overall, 377 shoulder arthroplasties composed of 247 anatomical total shoulder arthroplasties (aTSAs), 102 reverse total shoulder arthroplasties (RTSAs), and 28 hemiarthroplasties (HAs) were reported across 14 included studies at mean age 55.4 years, with 203 compared to 451 control shoulders in 7 matched case-control studies. The mean interval from arthroplasty to stabilization procedure was 19.7 years, with 27.2% of patients having undergone multiple procedures and 39.5% bone transfer procedures. Improvements in patient outcomes were observed both for patients who had underwent aTSA or RTSA, with the American Shoulder and Elbow Surgeons score the most commonly used scoring system. Across matched studies comparing to control, large improvements in American Shoulder and Elbow Surgeons were seen for both aTSA and RTSA implants, 38.1-80.5 and 34.9-82.3, which compared to control groups 38.0-85.5 and 35.5-82.3, respectively. There were differences observed in complication profiles between aTSA and RTSA procedures, with lower revision rates in the short-term to medium-term for RTSA implants in present literature. A significantly higher rate of aTSA revision was observed compared to matched control patients undergoing aTSA for primary osteoarthritis without previous stabilization surgery, 9.4% (13/139) vs. 4.1% (11/269) (P = .044). Aseptic loosening posed a particular challenge in the aTSA group, with significantly higher rates of 5.0% (7/139 f = 54.6 months) compared to control 0.74% (2/269 f = 49.1 months, P = .0088). No significant difference in infection rate was observed between matched study and control groups, 1.5% vs. 2.2% (P = .76). Conclusion: Shoulder arthroplasty may improve functional outcomes for patients experiencing instability arthropathy with a history of stabilization surgery. Careful consideration of potential complications is warranted both in surgical planning and patient counselling given the altered anatomy and biomechanics, with significantly higher revision and loosening rates observed following aTSA compared to control.</p