Staci R. Johnson

Extreme Variability in Posterior Slope of the Proximal Tibia: Measurements on 2395 CT Scans of Patients Undergoing UKA?

Data regarding the posterior slope of the tibia (PTS) are limited and sometimes conflicting. The purpose of this study was to determine the native posterior tibial slope in patients undergoing a medial or lateral UKA. A retrospective review was performed on 2395 CT scans in patients indicated for UKA, and the PTS of the osteoarthritic compartment was measured relative to a plane set perpendicular to the sagittal, tibial mechanical axis. The mean preoperative PTS in patients undergoing medial UKA was 6.8°+3.3°, with 34.3% between 4° and 7°. The mean preoperative PTS in patients undergoing lateral UKA was 8.0°+3.3°, with 27.5% between 4° and 7°. If attempting to recreate a patients preoperative tibial slope, a routine target of 5° to 7° will produce a posterior slope less than the patients native anatomy in 47% of patients undergoing UKA. This is the first, large CT-based review of posterior slope variation of the proximal tibia in patients undergoing UKA.

The Impact of Risk Reduction Initiatives on Readmission: THA and TKA Readmission Rates

We assessed whether sequential incorporation of initiatives to decrease postoperative surgical complications were similarly effective in reducing 30-day readmission rates following total knee arthroplasty (TKA) and total hip arthroplasty (THA). Readmission rates following TKA decreased substantially (5.6% vs. 3.0%, P<0.001), but readmissions following THA (4.0% vs. 3.4%, P=0.41) were not significantly reduced. The greatest impact of the multimodal treatment approach was a reduction of surgically related TKA complications. Advanced medical disease, facility discharge status, and Medicare or Medicaid coverage contributed to the highest risk for 30-day readmission after THA. Risk models defining expected readmission rates should account for these factors to avoid penalizing hospitals that provide higher proportional care to Centers for Medicaid and Medicare Services (CMS) beneficiaries.

Contemporary Surgical Indications and Referral Trends in Revision Total Hip Arthroplasty: A 10-Year Review

BACKGROUND Revision total hip arthroplasty (THA) represents nearly 15% of all hip arthroplasty procedures in the United States and is projected to increase. The purpose of our study was to summarize the contemporary indications for revision THA surgery at a tertiary referral medical center. We also sought to identify the indications for early and late revision surgery and define the prevalence of outside institution referral for revision THA. METHODS Using our institutions arthroplasty registry, we identified a retrospective cohort of 870 consecutive patients who underwent revision THA at our hospital from 2004 to 2014. Records were reviewed to collect data on patients primary and revision THA procedures, and the interval between primary THA and revision surgery was determined. RESULTS Aseptic loosening (31.3%), osteolysis (21.8%), and instability (21.4%) were the overall most common indications for revision THA and the most common indications for revision surgery within 5 years of primary THA. Aseptic loosening and osteolysis were the most common indications for revision greater than 5 years from primary THA. Only 16.4% of revised hips had their index arthroplasty performed at our hospital, whereas 83.6% were referred to our institution. CONCLUSIONS Aseptic loosening, osteolysis, and instability remain the most common contemporary indications for revision THA in an era of alternative bearings and modular components. Most of our revisions were referred from outside institutions, which highlights the transfer of a large portion of the revision THA burden to tertiary referral centers, a pattern that could be exacerbated under future bundled payment models.

Socioeconomically Disadvantaged CMS Beneficiaries Do Not Benefit From the Readmission Reduction Initiatives

We assessed the impact of minority and socioeconomic status on 30-day readmission rates after 3825 primary total hip arthroplasty (THA) and 3118 primary total knee arthroplasty (TKA) procedures. Minority patients had higher THA (7.4% vs 3.2%, P=0.001) and TKA (5.4% vs 3.7%, P<0.001) readmission rates. Low socioeconomic status was associated with higher THA (6.0% vs 3.1%, P<0.001) and TKA (6.3% vs 3.8%, P=0.02) readmission rates. Risk reduction initiatives were effective after TKA, but minority status and low socioeconomic status were still associated with higher 30-day readmission rates (4.6% vs 1.8%, P<0.01). Focused postoperative engagement for Centers for Medicare and Medicaid Services (CMS) beneficiaries less than 65 years of age may help reduce complications and 30-day readmissions.

Incidence and Location of Pain in Young, Active Patients Following Hip Arthroplasty

Persistent pain following hip arthroplasty remains a concern, especially in young, active patients. Four hundred twenty patients less than 60 years of age with a pre-symptomatic UCLA score ≥ 6 (196 total hip arthroplasty [THA]; 224 surface replacement arthroplasty [SRA]) completed a pain-drawing questionnaire investigating the location, severity, and frequency of pain around the hip. At a mean of 2.9 years of follow-up, 40% reported pain in at least one location around the hip. There was no difference in the incidence of groin pain between SRA and THA patients (32% vs. 29%, P=0.6), but THA patients had a greater incidence of anterior (25% vs. 8%, P<0.001) and lateral (20% vs. 10%, P=0.01) thigh pain. A high percentage of young, active patients experience persistent pain following hip arthroplasty.

Mobile Compression Devices and Aspirin for VTE Prophylaxis Following Simultaneous Bilateral Total Knee Arthroplasty

Recently, Levy et al questioned the effectiveness of mobile compression devices (MCDs) as the sole method of thromboprophylaxis following simultaneous bilateral total knee arthroplasty (TKA). This studys purpose was to assess if the addition of aspirin to MCDs improves venous thromboembolism (VTE) prevention following simultaneous bilateral TKA. Ninety-six patients (192 TKAs) were retrospectively reviewed: 47 patients received MCDs for 10 days and aspirin for 6 weeks postoperatively based on a risk stratification protocol, while 49 patients received warfarin for 4 weeks postoperatively. One symptomatic VTE was noted in the warfarin cohort, while one patient in the MCD/aspirin cohort and three patients in the warfarin cohort were readmitted within 3 months of surgery. In appropriately selected patients, MCDs with aspirin shows promise in VTE prevention following simultaneous bilateral TKA.

Metal Ion Concentrations in Young, Active Patients Following Total Hip Arthroplasty with the Use of Modern Bearing Couples

The purpose of this study was to compare whole blood metal ion levels in young, active patients undergoing primary total hip arthroplasty with the use of a cobalt-alloy (ten patients), ceramic (15 patients), or oxinium (11 patients) femoral head and highly crosslinked polyethylene acetabular liner. At 2 years postoperatively, mean cobalt concentrations were 3.0 times higher in the cobalt-alloy cohort versus the ceramic cohort, and 2.3 times higher versus the oxinium cohort (P=0.3-0.5). Titanium levels were consistently elevated at all postoperative time points versus preoperatively in all cohorts. Young, active patients following THA demonstrate elevated cobalt and titanium concentrations. Use of a ceramic or oxinium femoral head decreased the degree of cobalt elevation versus a cobalt-alloy femoral head, but did not reach statistical significance.

Radiographic parameters associated with pain following total hip and surface arthroplasty.

Pain following total hip arthroplasty (THA) and surface arthroplasty (SRA) remains a significant source of patient dissatisfaction. Two hundred twenty-four SRA and 196 THA patients completed a pain drawing questionnaire and postoperative radiographic measurements of component positioning were performed. In the SRA cohort, 11 of 21 patients (52%) with acetabular uncoverage of ≥5 mm versus 43 of 147 (29%) with acetabular uncoverage of ≤4.9 mm reported groin pain (P=.03). In the THA cohort, an increased distal-third canal fill ratio and a lower canal calcar ratio trended towards a higher incidence of thigh pain (P=.10 and .06), while a decreased mid-third canal fill ratio was associated with increased severity of thigh pain (P=.04). This study identifies associations between radiographic findings and pain following THA and SRA.

Clinical outcomes following re-admission for non-infectious wound complications after primary total knee replacement

Haematomas, drainage, and other non-infectious wound complications following total knee replacement (TKR) have been associated with long-term sequelae, in particular, deep infection. However, the impact of these wound complications on clinical outcome is unknown. This study compares results in 15 patients re-admitted for wound complications within 90 days of TKR to 30 matched patients who underwent uncomplicated total knee replacements. Patients with wound complications had a mean age of 66 years (49 to 83) and mean body mass index (BMI) of 37 (21 to 54), both similar to that of patients without complications (mean age 65 years and mean BMI 35). Those with complications had lower mean Knee Society function scores (46 (0 to 100 vs. 66 (20 to 100), p = 0.047) and a higher incidence of mild or greater pain (73% vs. 33%, p = 0.01) after two years compared with the non re-admitted group. Expectations in patients with wound complications following TKR should be tempered, even in those who do not develop an infection.

Planned Bone Resections Using an MRI-Based Custom Cutting Guide System Versus 3-Dimensional, Weight-Bearing Images in Total Knee Arthroplasty

Potential sources of alignment variability not yet investigated with the use of custom cutting guides (CCG) in total knee arthroplasty (TKA) are weight-bearing and lower extremity rotation. This study compared the preoperative planned bone resections created using an MRI-based CCG system to those from 3-dimensional, weight-bearing, full-length lower extremity images in 53 patients undergoing TKA. The angular difference between the proposed resections of the two systems was greater than 2° in 30.2% of patients for the distal femur, and 52.8% for the proximal tibia. An increased preoperative varus alignment had a slight association with an increased angular difference for the tibial resection (r=0.4). This study demonstrates weight-bearing and lower extremity rotation to be potential sources of alignment variability when using MRI-based CCGs.