High Prevalence of Radiographic Outliers and Revisions with Unicompartmental Knee Arthroplasty.

BACKGROUND: Alignment outcomes and their impact on implant survival following unicompartmental knee arthroplasty (UKA) are unclear. The purpose of this study was to assess the implant survival and radiographic outcomes after UKA as well as the impact of component alignment and overhang on implant survival. METHODS: We performed a retrospective analysis of 253 primary fixed-bearing and mobile-bearing medial UKAs from a single academic center. All UKAs were performed by 2 high-volume fellowship-trained arthroplasty surgeons. UKAs comprised <10% of their knee arthroplasty practices, with an average of 14.2 medial UKAs per surgeon per year. Implant survival was assessed. Femoral coronal (FCA), femoral sagittal (FSA), tibial coronal (TCA), and tibial sagittal (TSA) angles as well as implant overhang were radiographically measured. Outliers were defined for FCA (>±10° deviation from neutral), FSA (>15° of flexion), TCA (>±5° deviation from neutral), and TSA (>±5° deviation from 7°). "Far outliers" were an additional >±2° of deviation. Outliers for overhang were identified as >3 mm for anterior overhang, >2 mm for posterior overhang, and >2 mm for medial overhang. RESULTS: Among patients with a failed UKA, revision was performed at an average of 3.7 years (range, 0.03 to 8.7 years). The cumulative revision rate was 14.2%. Kaplan-Meier survival analysis demonstrated 5 and 10-year survival rates of 88.0% (95% confidence interval [CI] = 82.0% to 91.0%) and 70.0% (95% CI = 56.0% to 80.0%), respectively. Only 19.0% (48) of the UKAs met target alignment for all 4 alignment measures, and only 72.7% (184) met all 3 targets for overhang. Only 11.9% (30) fell within all alignment and overhang targets. The risk of implant failure was significantly impacted by outliers for FCA (failure rate = 15.4%, p = 0.036), FSA (16.2%, p = 0.028), TCA (17.9%, p = 0.020), and TSA (15.2%, p = 0.034) compared with implants with no alignment or overhang errors (0%); this was also true for far outliers (p < 0.05). Other risk factors for failure were posterior overhang (failure rate = 25.0%, p = 0.006) and medial overhang (38.2%, p < 0.001); anterior overhang was not a significant risk factor (10.0%, p = 0.090). CONCLUSIONS: The proportions of UKA revisions and alignment outliers were greater than expected, even among high-volume arthroplasty surgeons performing an average of 14.2 UKAs per year (just below the high-volume UKA threshold of 15). Alignment and overhang outliers were significant risk factors for implant failure. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Pullout strength of standard vs. cement-augmented rotator cuff repair anchors in cadaveric bone.

BACKGROUND: We evaluate a novel method of rotator cuff repair that uses arthroscopic equipment to inject bone cement into placed suture anchors. A cadaver model was used to assess the pullout strength of this technique versus anchors without augmentation. METHODS: Six fresh-frozen matched pairs of upper extremities were screened to exclude those with prior operative procedures, fractures, or neoplasms. One side from each pair was randomized to undergo standard anchor fixation with the contralateral side to undergo anchor fixation augmented with bone cement. After anchor fixation, specimens were mounted on a servohydraulic testing system and suture anchors were pulled at 90° to the insertion to simulate the anatomic pull of the rotator cuff. Sutures were pulled at 1 mm/s until failure. FINDINGS: The mean pullout strength was 540 N (95% confidence interval, 389 to 690 N) for augmented anchors and 202 N (95% confidence interval, 100 to 305 N) for standard anchors. The difference in pullout strength was statistically significant (P < 0.05). INTERPRETATION: This study shows superior pullout strength of a novel augmented rotator cuff anchor technique. The described technique, which is achieved by extruding polymethylmethacrylate cement through a cannulated in situ suture anchor with fenestrations, significantly increased the ultimate failure load in cadaveric human humeri. This novel augmented fixation technique was simple and can be implemented with existing instrumentation. In osteoporotic bone, it may substantially reduce the rate of anchor failure.

Novel Technique for Sacral Alar-Iliac (S2AI) Fixation.

OBJECTIVE: To provide reasoning and steps for the placement of sacral alar-iliac (S2AI) screws for pelvic arthrodesis to aid osseous lumbosacral fusion. SUMMARY OF BACKGROUND DATA: Studies support lower rates of screw breakage and need for revision surgery or hardware removal for S2AI screws compared with traditional iliac bolts, as well as low rates of pseudoarthrosis and arthritis associated with this hardware placement. MATERIALS AND METHODS: A case video of S2AI placement demonstrates our operative technique and is accompanied by procedural description of surgical maneuvers. RESULTS AND SURGICAL TECHNIQUES: One patient underwent lumbosacral fusion surgery aided by S2AI-mediated pelvic fixation. CONCLUSIONS: The present technique utilizing S2AI screws provides for successful pelvic fixation to aid in lumbosacral fusion, with no need for subcutaneous tissue dissection and improved outcomes compared with traditional iliac bolts.

Post-Discharge Care Duration, Charges, and Outcomes Among Medicare Patients After Primary Total Hip and Knee Arthroplasty.

BACKGROUND: In April 2016, the U.S. Centers for Medicare & Medicaid Services initiated mandatory 90-day bundled payments for total hip and knee arthroplasty for much of the country. Our goal was to determine duration of care, 90-day charges, and readmission rates by discharge disposition and U.S. region after hip or knee arthroplasty. METHODS: Using the 2008 Medicare Provider Analysis and Review database 100% sample, we identified patients who had undergone elective primary total hip or knee arthroplasty. We collected data on patient age, sex, comorbidities, U.S. Census region, discharge disposition, duration of care, 90-day charges, and readmission. Multivariate regression was used to assess factors associated with readmission (logistic) and charges (linear). Significance was set at p < 0.01. RESULTS: Patients undergoing 138,842 total hip arthroplasties were discharged to home (18%), home health care (34%), extended-care facilities (35%), and inpatient rehabilitation (13%); patients undergoing 329,233 total knee arthroplasties were discharged to home (21%), home health care (38%), extended-care facilities (31%), and inpatient rehabilitation (10%). Patients in the Northeast were more likely to be discharged to extended-care facilities or inpatient rehabilitation than patients in other regions. Patients in the West had the highest 90-day charges. Approximately 70% of patients were discharged home from extended-care facilities, whereas after inpatient rehabilitation, >50% of patients received home health care. Among those discharged to home, 90-day readmission rates were highest in the South (9.6%) for patients undergoing total hip arthroplasty and in the Midwest (8.7%) and the South (8.5%) for patients undergoing total knee arthroplasty. Having ≥4 comorbidities, followed by discharge to inpatient rehabilitation or an extended-care facility, had the strongest associations with readmission, whereas the region of the West and the discharge disposition to inpatient rehabilitation had the strongest association with higher charges. CONCLUSIONS: Among Medicare patients, discharge disposition and number of comorbidities were most strongly associated with readmission. Inpatient rehabilitation and the West region had the strongest associations with higher charges. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Prevention training of wrong-site spine surgery.

OBJECTIVE: Wrong-site surgery (WSS) is considered a sentinel event by the Joint Commission. The education of spine surgery fellows on WSS is unknown. Our objective was to evaluate North American spine surgery fellows' education, awareness, and experience with WSS. DESIGN: Observational survey study. SETTING: Spine surgery fellows in North America. PARTICIPANTS: From April 2013 to July 2013 and in July 2014 anonymous questionnaires were sent to 156 spine surgery fellows participating in 75 programs. Demographic information (fellowship location and Accreditation Council for Graduate Medical Education accreditation of the fellowship) were collected. We also collected data on the following: if didactics on WSS are offered during fellowship, spine surgery fellows' experience with WSS, WSS prevention methods used during fellowship, and whether spine surgery fellows are interested in didactics or webinars on the prevention of WSS. RESULTS: Of 152 spine surgery fellows, 46 (30.3%) completed the questionnaires. Among them, 39 (84.6%) were orthopedic surgeons and 7 (15.4%) were neurosurgeons. Most were in non-Accreditation Council for Graduate Medical Education-accredited programs (70%) and were in training in the Midwest (37%), the South (30.4%), the Northeast (15.2%), and the West (15.2%). Furthermore, 30.4% had experienced WSS. Only 15 fellows (33%) had formal didactics on WSS during their fellowship. Most spine surgery fellows (61%, p = 0.03) were interested in a formal didactics on the prevention of WSS during their fellowship curriculum. Most (58.7%) were also interested in a Webinar on the prevention of WSS. We found of the 14 fellows that experienced WSS, 11 (79%) were significantly interested in formal didactics on WSS compared with those who had not experienced WSS (14/32, 44%; p < 0.02). CONCLUSIONS: This is the first study evaluating spine surgery fellowship education on WSS. Among the spine surgery fellows, 30% had already experienced WSS and only 33% had formal fellowship didactics on WSS. Owing to the significant patient care and medicolegal ramifications from WSS, spine surgery fellowships should consider adding WSS prevention didactics to their curriculum.