A Smart Tool for Intraoperative Leg Length Targeting in Total Hip Arthroplasty: A Retrospective Cohort Study.

BACKGROUND: Leg length discrepancies following total hip arthroplasty (THA) may necessitate subsequent interventions, from heel lifts to revision surgery. Current intraoperative methods of determining leg length are either inaccurate or expensive and invasive. OBJECTIVE: The objective of the current study was to investigate the ability of a novel, intraoperative smart tool (Intellijoint HIP®, Intellijoint Surgical®, Inc., Waterloo, ON) to provide accurate, real-time leg length measurements during THA. METHODS: We retrospectively reviewed the medical records of 25 patients who underwent THA utilizing the Intellijoint HIP smart tool between February and August 2014. Intraoperative leg length data was compared with radiographic leg length calculations. Two observers blinded to the Intellijoint HIP findings independently assessed all post-procedure radiographs. RESULTS: The mean difference between smart tool and radiographic measurements was 1.3 mm [CI: -0.1, 2.7]. 88% (22/25) of intraoperative measurements were within 5 mm of radiographic measurements; 100% (25/25) were within 10 mm. A Bland-Altman analysis showed excellent agreement, with 96% (24/25) of measurements within the statistical limit for acceptable agreement, and 84% (21/25) within the clinically acceptable range (± 5 mm). Removal of the first 13 procedures (surgeon training) decreased the mean difference between methods to 0.6 mm [-0.6, 1.9]. All post-training procedures were associated with a difference of <5 mm. There were no reported adverse events related to the use of the smart tool. CONCLUSION: The Intellijoint HIP smart tool is a safe and accurate tool for providing intraoperative measurements of leg length in real-time.

What are the predictors and prevalence of pseudotumor and elevated metal ions after large-diameter metal-on-metal THA?

BACKGROUND: Soft tissue masses, or "pseudotumors," around metal-on-metal total hip arthroplasty (MoM THA) have been reported frequently; however, their prevalence remains unknown. Several risk factors, including elevated metal ion levels, have been associated with the presence of pseudotumor, although this remains controversial. QUESTIONS/PURPOSES: The goals of this study were to (1) determine the prevalence of pseudotumors after large-diameter head MoM THA; (2) identify risk factors associated with pseudotumor formation and elevated metal ion levels; and (3) determine the early failure rate of large-diameter MoM THA. METHODS: Between December 2005 and November 2012, 258 hips (215 patients) underwent large-diameter head primary MoM THA at our institution. Clinical followup was obtained in 235 hips (91%). Using an inclusion criteria of a minimum followup of 1 year, a subset of 191 hips (mean followup, 4 years; range, 1-7 years) was recruited for high-resolution ultrasound screening for the presence of pseudotumor. Whole blood cobalt and chromium ion levels, UCLA activity level, WOMAC score, patient demographics as well as surgical, implant, and radiographic data were collected. Bivariate correlations and multivariate log-linear regression models were used to compare the presence of pseudotumor and elevated metal ions with all other factors. RESULTS: Ultrasound detected a solid, cystic, or mixed mass in 20% hips (38 of 191). No correlation was found between the presence of pseudotumor and any risk factor that we examined. After controlling for confounding variables, elevated cobalt ions were correlated (p<0.001, R=0.50, R2=0.25) with smaller femoral head size, the presence of bilateral MoM THA, and female sex. Elevated chromium ions were correlated (p<0.001, R=0.59, R2=0.34) with smaller femoral head size, presence of bilateral MoM THA, and lower body mass index. The overall survival of MoM THA was 96% at a mean followup of 4.5 years (range, 2-8 years). CONCLUSIONS: With the numbers available, we found no associations between the presence of pseudotumor and the potential risk factors we analyzed, including elevated metal ion levels. Further work is needed to explain why larger femoral head sizes resulted in lower metal ion levels despite being associated with higher early failure rates in joint registry data. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Shoulder arthroplasty for patients with juvenile idiopathic arthritis.

Between 1986 and 1997, 13 shoulders in adult patients who had severe polyarticular juvenile idiopathic arthritis were treated with primary arthroplasty. Eleven shoulders were evaluated retrospectively by an independent observer with a mean follow-up of 9 years. Patient evaluation included pain Visual Analogue Scale, range of motion, Disabilities of the Arm, Shoulder and Hand score, and Short-Form 36. Patients' pain decreased significantly after surgery (mean 6.7). Forward elevation improved on average by 41.1 degrees and external rotation by 39.1 degrees , without evidence of shoulder instability. Final Short-Form 36 scores and Disabilities of the Arm, Shoulder and Hand results (mean, 44.7) were poor, but all patients rated themselves satisfied with the procedure. Shoulder arthroplasty provided pain relief for end-stage shoulder involvement in adult juvenile idiopathic arthritis. Improvement in external rotation in this severely affected group appears to have a beneficial effect on functional outcome.

Provider volume and other predictors of outcome after total knee arthroplasty: a population study in Ontario.

INTRODUCTION: Because of rationing of the limited pool of health care resources, access to total knee arthroplasty (TKA) is limited, but investigation of variables that predict complications, length of hospital stay, cost and outcomes of TKA may allow us to optimize the available resources. The objective of this study was to examine the effect of various factors on complication rates after TKA in patients managed in Ontario. METHODS: Patients who had undergone an elective TKA between 1993 and 1996, as captured in the Canadian Institute for Health Information (CIHI) database, formed the study cohort. The CIHI dataset was used to obtain information regarding in-hospital complications, hospital length of stay, revision rates, infection rates and mortality. Generalized estimating linear or logistic regression equations were used to model outcomes as a function of age, gender, comorbidity, diagnosis and provider volume. RESULTS: During the study period, 14,352 patients in Ontario underwent TKA. Mortality at 3 months was associated with patient age, gender and comorbidity. There was no association between provider volume and mortality or the infection rate. Higher revision rates at 1 and 3 years were significantly associated with lower patient age and low hospital volume (p < 0.05). Hospitals in which fewer than 48 TKA procedures were done per year (< 40th percentile) had 2.2-fold greater 1-year revision rates than hospitals performing more than 113 TKAs annually (> 80th percentile). Complications during admission were associated with increased patient age and comorbidity, and higher hospital volume. Longer hospital stay was associated with female gender, increasing patient comorbidity and age, and lower provider volume. Surgeons who performed fewer than 14 TKAs annually (< 40th percentile) kept patients in hospital an average of 1.4 days longer than surgeons performing more than 42 TKAs annually (> 80th percentile). CONCLUSIONS: Patient variables significantly affect the rate of complications. Age, sex and comorbidity were significant predictors of complications, length of hospital stay and mortality after TKA. Although low surgeon volume was related to longer hospital stay, there was no association between surgeon volume and complication rates. The increased early revision rate for low-volume hospitals demands further study.