The Learning Curve From Converting From Fluoroscopic to Robotic-Assisted Direct Anterior Total Hip Arthroplasty.

INTRODUCTION: Robotic-assisted total hip arthroplasty (RA-THA) provides an alternative to fluoroscopic guidance, thus reducing radiation exposure for orthopaedic surgeons. This study was performed to assess the learning curve associated with the adoption of RA-THA using the direct anterior approach (DAA) with regard to surgical time, use of fluoroscopy, and implant placement. In addition, we compared complication rates and patient-reported outcome scores between both cohorts. A case report of an RA-THA is also presented. MATERIALS AND METHODS: This was a retrospective, non-randomized evaluation of the learning curve by assessing surgical time on a consecutive series of 89 DAA cases performed by a single surgeon. There were 53 cases that had manual THA with fluoroscopy and 36 cases with RA-THA. All cases had an acetabular component placement target of 40° inclination and 20° anteversion. An independent reviewer blinded to surgical technique used the Widmer method to measure acetabular inclination and version. Patient demographics were similar for both groups. RESULTS: The mean surgical time for the manual fluoroscopic group was 88 ± 21 minutes and 101 ± 14 minutes for the RA-THA group. After 15 RA-THA cases, surgical time reached time neutral compared to the manual fluoroscopic group. The first 17 RA-THA cases utilized fluoroscopy to verify implant position until the surgeon became comfortable with the accuracy of the RA-THA system. After case 17, fluoroscopy was abandoned in all subsequent RA-THA cases. The mean radiation dose delivered to the surgical field was 5.61 ± 5.71 mGy. Manual THA with fluoroscopy resulted in a mean acetabular inclination of 41.3 ± 4.4° and a mean anteversion of 22.4 ± 3.0°. The RA-THA resulted in a mean acetabular inclination of 42.0 ± 4.2° and a mean anteversion of 22.3 ± 3.9°. There was no noted change in RA-THA placement accuracy after case 17, when fluoroscopy was eliminated from the surgical workflow. There were no statistical differences between the manual fluoroscopic and robotic-assisted groups with respect to complications and clinical PROM outcomes. CONCLUSION: The DAA THA can be performed with RA-THA and achieve comparable acetabular placement without fluoroscopy. Surgical time was higher for the RA-THA group during the learning curve, but then decreased and was consistent with the manual fluoroscopic group after 15 cases.

How Much Perioperative Pain and Dysfunction Underlie the HOOS JR and KOOS JR?

BACKGROUND: The Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR) and Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR) scores represent pain and dysfunction as a single number ranging from 0 (extreme pain and dysfunction) to 100 (no pain or functional limitations). However, scores between 0 and 100 lack a simple interpretation because they reflect varying combinations of pain levels and dysfunction. Given that most adverse events and improvement occur within the first 90 days after surgery, a deeper understanding of the level of pain and dysfunction may reveal missed opportunities for patient care. QUESTIONS/PURPOSES: (1) What does a given preoperative or postoperative HOOS JR and KOOS JR score indicate about pain and ability to perform daily activities? (2) How much of a change in score (that is, delta) is needed to indicate significant improvement in pain control and daily functioning? METHODS: The Michigan Arthroplasty Registry Collaborative Quality Initiative contains more than 95% of THAs and TKAs performed in Michigan. Between January 2017 and March 2019, 84,175 people in the registry underwent primary THA or TKA and were potentially eligible for this retrospective, comparative study of the first 90 postoperative days. Eighty-four percent (70,608 of 84,175) were excluded because their surgeons did not attain a target survey collection proportion of 70% and another 6% (5042) were missing covariate information or surveys, leaving 10% (8525) for analysis. The mean age and percentage of women were 65 ± 11 years and 55% (2060 of 3716), respectively, for patients undergoing THA and 67 ± 9 years and 61% (2936 of 4809), respectively, for those undergoing TKA. There were no clinically meaningful differences between patients who were analyzed and those who were excluded except for lower representation of non-White patients in the analyzed group. For interpretation, patient responses to Question 7 (pain) and Question 6 (function) from the Patient-Reported Outcomes Measurement Information System global items (PROMIS-10) were dichotomized into "much pain" (rating of pain 4 to 10 of 10) versus "less pain" (rating of ≤ 3) and "good function" (able to perform most activities) versus "poor function" (not able to perform most activities) and combined into four pain-function categories. We examined the mean preoperative and postoperative HOOS JR and KOOS JR scores for each pain-function category, adjusted for patient characteristics. We calculated the size of the delta associated with an increase to a more favorable category postoperatively (versus staying in the same or worse category) via multivariable logistic regression that controlled for patient characteristics. RESULTS: Patients in the least favorable "much pain, poor function" category preoperatively had adjusted mean scores of 40 (95% confidence interval 39 to 41) for both the HOOS JR and KOOS JR. Those with mixed levels of pain and function had mean scores between 46 and 55. Those in the most favorable "less pain, good function" category had means of 60 (95% CI 58 to 62) and 59 (95% CI 58 to 61) for the HOOS JR and KOOS JR, respectively. The adjusted delta to achieve a pain level of ≤ 3 or the ability to perform most activities was 30 (95% CI 26 to 36) on the HOOS JR and 27 (95% CI 22 to 29) on the KOOS JR scales. CONCLUSION: These adjusted means of the HOOS JR and KOOS JR provide context for understanding the levels of pain and dysfunction for individuals as well for patients reported in other studies. Potential quality improvement efforts could include tracking the proportion of patients with THA or TKA who achieved a sufficient delta to attain pain levels of ≤ 3 or the ability to perform most activities. Future studies are needed to understand pain and function represented by the HOOS JR and KOOS JR at 1 to 2 years, how these may differ by patient subgroups, and whether scores can be improved through quality improvement efforts. LEVEL OF EVIDENCE: Level III, therapeutic study.

Are Short Stems Associated With Higher Fracture Rates and Early Revision Rates in Primary Total Hip Arthroplasty? A Noninferiority Analysis.

BACKGROUND: This study aimed to determine if "short" femoral stems were noninferior to (at least as good as) standard-length stems in regards to 90-day periprosthetic fracture and 1-year revision rates. METHODS: Using the MARCQI implant registry, a retrospective study of statewide data was carried out on 64,084 total hip arthroplasties (THAs) between 2012 and 2017. We noticed an increase in the use of "short" uncemented femoral hip stems during THA. Chi-square tests were used to test homogeneity of categorical variables. The covariates included in the analyses were identified using modern epidemiological methods. A Type I probability of 0.05 was used as the level of statistical significance. Inverse probability of treatment weighting (IPTW) was used to mitigate confounding variables. RESULTS: One hundred and seven stems were implanted by surgeons in the state of Michigan. They were classified according to the Khanuja Classification System as Type 2A (trapezoidal, double-tapered calcar loading, n = 3,281), Type 3 (calcar loading with lateral flare, n = 1,898), and Type 4 (shortened, tapered, conventional, n = 19,580), and were compared to standard-length, type 5, stems (n = 33,322) in regards to the 2 outcomes (periprosthetic fractures and 1-year revision rates). Overall, 1-year revision and the 90-day fracture rates were 1.3% (791/57,853) and 1.1% (631/57,968), respectively. Noninferiority was established for all short stems at the clinical threshold of an odds ratio (OR) of 1.5 with P-values <0.05 for 90-day fractures. In regards to 1-year revision rates, noninferiority was also established for Type 3 and 4 stems (P < .05). CONCLUSION: The increased use of "short stems" in Michigan did not lead to increased 1-year revision or 90-day fracture rates.

Data Sharing Between Providers and Quality Initiatives Eliminate Unnecessary Nursing Home Admissions.

BACKGROUND: The Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI) has monitored discharge disposition, after total hip and knee arthroplasties, since inception in 2012 and found the standardized risk of extended care facility (ECF) placement to be highly variable between hospitals. METHODS: The variation in standardized risks of ECF placement among MARCQI member sites was reported to the collaborative. At the May 2, 2014 quarterly meeting, a quality initiative was started, emphasizing the wide variability between hospitals, the contribution of hospital and surgeon to that variability using median odds ratios, and the need for outlier hospitals to initiate quality improvement (QI) processes. Patients from 29 hospitals that were members of MARCQI before the intervention were included in this analysis. We compared standardized risks before and after the intervention in the entire cohort, and for 3 hospitals that implemented institution-specific QI projects. We report changes in ECF placement, length of stay, emergency room visits, and readmissions over time. RESULTS: This study includes 31,347 patients before and 20,879 patients after the implementation of the quality initiative. The range in standardized risk dropped from 9.4%-46.1% to 9.4%-32.4% and the average dropped from 23.0% to 19.6%. Three outlier hospitals decreased their absolute risk of ECF placement by 12.2%, 8.9%, and 12.4% after QI, without increases in adverse outcomes. CONCLUSION: Discharge to ECF after primary hip and knee arthroplasties is highly variable and influenced by hospital and surgeon practices. Hospital-level QI measures can decrease ECF admissions.

Outcomes of Second-Generation Tapered Wedge Femoral Stem.

INTRODUCTION: Newer generation cementless femoral stems have been designed to emulate more precisely the anatomy of the native femur. However, few studies have evaluated these designs. The purpose of this study was therefore to evaluate outcomes of primary total hip arthroplasty (THA) in patients who received a second-generation, tapered wedge stem by analyzing (1) all-cause and aseptic implant survivorships; (2) clinical and patient-reported outcomes; (3) radiographic outcomes; and (4) incidence of complications. MATERIALS AND METHODS: We evaluated 202 primary THA patients (37% men, 63% women) who had a mean age of 63 years (range, 18 to 88) and a mean body mass index (BMI) of 29 (range, 18 to 40). All patients underwent THA using a press-fit, tapered wedge stem with a morphometric design containing a size-specific medial curvature, which optimizes initial press-fit stability. Kaplan-Meier analysis was performed to determine implant survivorship, and Harris Hip Scores (HHS) and the Short form-36 (SF-36) were used to evaluate clinical and patient-reported outcomes. Early postoperatively and annually thereafter, pelvic radiographs were reviewed for evidence of osteolysis or loosening. Complications were identified through a comprehensive chart review and were classified as either surgical or medical. RESULTS: At final follow-up, the all-cause and aseptic survivorships for the femoral stem were 99.5% and 100%, respectively. At final follow-up, the mean HHS was 87 (range, 35 to 100). The SF-36 mental and physical component scores were 47 (range, 19 to 65) and 47 (range, 23 to 65), respectively, at final follow-up. No progressive radiolucencies or loosening were observed. Surgical complications included nerve palsy, posterior trochanteric avulsion, arthrofibrosis, and periprosthetic fracture. The only medical complication was acute renal failure. CONCLUSION: This second-generation stem demonstrated excellent short-term survivorship and functional outcomes. The improved patient fit of this stem may yield continued favorable results with longer-term follow-up.