Hospital Costs for Unsuccessful Two-Stage Revisions for Periprosthetic Joint Infection.

BACKGROUND: Although 2-stage exchange arthroplasty is the preferred surgical treatment for periprosthetic joint infection (PJI) in the United States, little is known about the risk of complications between stages, mortality, and the economic burden of unsuccessful 2-stage procedures. METHODS: The 2015-2019 Medicare 100% inpatient sample was used to identify 2-stage PJI revisions in total hip and knee arthroplasty patients using procedural codes. We used the Fine and Gray sub-distribution adaptation of the conventional Kaplan-Meier method to estimate the probability of completing the second stage of the 2-stage PJI infection treatment, accounting for death as a competing risk. Hospital costs were estimated from the hospital charges using "cost-to-charge" ratios from Centers for Medicare and Medicaid Services. RESULTS: A total of 5094 total hip arthroplasty and 13,062 total knee arthroplasty patients had an index revision for PJI during the study period. In the first 12 months following the first-stage explantation, the likelihood of completing a second-stage PJI revision was 43.1% (95% confidence interval [CI] 41.7-44.5) for hips and 47.9% (95% CI 47.0-48.8) for knees. Following explantation, 1-year patient survival rates for hip and knee patients were 87.4% (95% CI 85.8-88.9) and 91.4% (95% CI 90.6-92.2), respectively. The median additional cost for hospitalizations between stages was $23,582 and $20,965 per patient for hips and knees, respectively. Hospital volume, Northeast or Midwest region, and younger age were associated with reduced PJI costs (P < .05). CONCLUSION: Although viewed as the most preferred, the 2-stage revision strategy for PJI had less than a 50% chance of successful completion within the first year, and was associated with high mortality rates and substantial costs for treatment failure.

Patient Perceptions of Wearable and Smartphone Technologies for Remote Outcome Monitoring in Patients Who Have Hip Osteoarthritis or Arthroplasties.

BACKGROUND: Although there is interest in wearables and smartphone technologies for remote outcome monitoring, little is known regarding the willingness of hip osteoarthritis (OA) and/or total hip arthroplasty (THA) patients to authorize and adhere to such treatment. METHODS: We developed an Institutional Review Board-approved questionnaire to evaluate patient perceptions of remote monitoring technologies in a high-volume orthopedic center. Forty-seven THA patients (60% female; mean age: 66 years) and 50 nonoperative OA hip patients (52% female; mean age: 63 years) participated. Patient perceptions were compared using Pearson's chi-squared analyses. RESULTS: THA patients were similarly interested in the use of smartphone apps (91% vs 94%, P = .695) in comparison to nonoperative hip OA patients. THA patients were more receptive to using wearable sensors (94% vs 44%, P < .001) relative to their nonoperative counterparts. THA patients also expressed stronger interest in learning to use custom wearables (87% vs 32%, P < .001) vs nonoperative patients. Likewise, the majority of THA patients were willing to use Global Positioning System technology (74% vs 26%, P < .001). THA patients also expressed willingness to have their body movement (89%), balance (89%), sleep (87%), and cardiac output (91%) tracked using remote technology. CONCLUSION: Overall, we found that THA patients were highly receptive to using wearable technology in their treatments. Nonoperative OA hip patients were generally unreceptive to using smart technologies, with the exception of smartphone applications. This information may be useful as utilization of these technologies for patient care continues to evolve.

Oxidation, Damage Mechanisms, and Reasons for Revision of Sequentially Annealed Highly Crosslinked Polyethylene in Total Knee Arthroplasty.

BACKGROUND: Sequentially annealed, highly crosslinked polyethylene (HXLPE) has been used clinically in total knee arthroplasty (TKA) for over a decade. However, little is known about the revision reasons; its surface damage mechanisms; or its in vivo oxidative stability relative to conventional polyethylene. We asked whether retrieved HLXPE tibial inserts exhibited: (1) similar revision reasons; (2) improved resistance to surface damage; and (3) improved oxidative stability, when compared with conventional gamma inert sterilized polyethylene inserts. METHODS: A total of 456 revised tibial inserts were collected in a multicenter retrieval program between 2000 and 2016. The implantation time for the HXLPE components was 1.8 ± 1.8 years, and for the control inserts it was 3.4 ± 2.7 years. Revision reasons were assessed based on medical records, radiographs, and examinations of the retrieved components. Surface damage was assessed using a semi-quantitative scoring method. Oxidation was measured using Fourier transform infrared spectroscopy. RESULTS: The tibial inserts in both cohorts were revised most frequently for loosening, infection, and instability. The most commonly observed surface damage modes were burnishing, pitting, and scratching. Oxidation of the HXLPE inserts was, on average, low and similar to the control inserts at the bearing surface and the stabilizing post. CONCLUSIONS: We observed evidence of in vivo oxidation in both HXLPE and control tibial inserts. We found no association between the levels of oxidation and the clinical performance of the HXLPE tibial components. The findings of this study document the revision reasons, surface damage modes, and oxidative behavior of sequentially annealed HXLPE for TKA.

Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head.

BACKGROUND: Gross trunnion failure (GTF) is a rare complication in total hip arthroplasty (THA) reported across a range of manufacturers. Specific lots of the Stryker low friction ion treatment (LFIT) anatomic cobalt chromium alloy (CoCr) V40 femoral head were recalled in August 2016. In part, the recall was based out of concerns for disassociation of the femoral head from the stem and GTF. METHODS: We report on 28 patients (30 implants) with either GTF (n = 18) or head-neck taper corrosion (n = 12) of the LFIT CoCr femoral head and the Accolade titanium-molybdenum-zirconium-iron alloy femoral stems. All these cases were associated with adverse local tissue reactions requiring revision of the THA. RESULTS: In our series, a conservative estimate of the incidence of failure was 4.7% (n = 636 total implanted) at 8.0 ± 1.4 years from the index procedure. Failures were associated with a high-offset 127° femoral stem neck angle and increased neck lengths; 43.3% (13 of 30) of the observed failures included implant sizes outside the voluntary recall (27.8% [5 of 18] of the GTF and 75.0% [8 of 12] of the taper corrosion cases). Serum cobalt and chromium levels were elevated (cobalt: 8.4 ± 7.0 µg/mL; chromium: 3.4 ± 3.3 µ/L; cobalt/chromium ratio: 3.7). The metal artifact reduction sequence magnetic resonance imaging demonstrated large cystic fluid collections typical with adverse local tissue reactions. During revision, a pseudotumor was observed in all cases. Pathology suggested a chronic inflammatory response. Impending GTF could be diagnosed based on aspiration of black synovial fluid and an oblique femoral head as compared with the neck taper on radiographs. CONCLUSION: In our series of the recalled LFIT CoCr femoral head, the risk of impending GTF or head-neck taper corrosion should be considered as a potential diagnosis in a painful LFIT femoral head and Accolade titanium-molybdenum-zirconium-iron alloy THA with unknown etiology. Almost half of the failures we observed included sizes outside of the voluntary recall.

Does Taper Size Have an Effect on Taper Damage in Retrieved Metal-on-Polyethylene Total Hip Devices?

BACKGROUND: Taper design has been identified as a possible contributor to fretting corrosion damage at modular connections in total hip arthroplasty systems, but variations in as-manufactured taper interfaces may confound this analysis. This study characterized taper damage in retrievals with 2 different taper sizes but comparable taper surface finishes and investigated if fretting and corrosion damage is related to taper size in the context of a multivariable analysis for metal-on-polyethylene bearings. METHODS: A total of 252 cobalt chromium femoral heads were identified in a collection of retrievals: 77 with taper A and 175 with taper B. Implantation time averaged 5.4 ± 6.0 years (range, 0-26 years). Explants were cleaned and analyzed using a 4-point semiquantitative method. Clinical and device factors related to head taper fretting corrosion damage were assessed using ordinal logistic regression with forward stepwise control. Components were then selected to create 2 balanced cohorts, matched on significant variables from the multivariable analysis. RESULTS: Increased head offset (P < .001), longer implantation time (P = .002), heavier patients (P < .001), and more flexible tapers (P < .001) were associated with increased taper fretting and corrosion damage. When damage scores were compared between the balanced groups, no significant differences were found. CONCLUSION: These results suggest that fretting and corrosion damage is insensitive to differences in taper size. The final model derived explains almost half of the fretting corrosion damage observed and identifies contributing factors that are consistent with other in vitro and retrieval studies.

Is increased modularity associated with increased fretting and corrosion damage in metal-on-metal total hip arthroplasty devices?: a retrieval study.

This retrieval study documents taper damage at modular interfaces in retrieved MOM THA systems and investigates if increased modularity is associated with increased fretting and corrosion. One hundred thirty-four (134) heads and 60 stems (41 modular necks) of 8 different bearing designs (5 manufacturers) were analyzed. Damage at the shell-liner interface of 18 modular CoCr acetabular liners and the corresponding 11 acetabular shells was also evaluated. The results of this study support the hypothesis that fretting and corrosion damage occurs at a variety of modular component interfaces in contemporary MOM THAs. We also found that modularity of the femoral stem was associated with increased damage at the head. An analysis of component and patient variables revealed that dissimilar alloy pairing, larger head sizes, increased medio-lateral offsets and longer neck moment arms were all associated with increased taper damage at the modular interfaces.

Patient Perceptions of Wearable and Smartphone Technologies for Remote Outcome Monitoring in Total Knee Arthroplasties.

While there is enthusiasm for wearables and smartphone technologies in evaluating clinical outcomes among clinicians, less is known about the willingness of patients who have osteoarthritis (OA) to consent for remote outcome monitoring. We developed an Institutional Review Board-approved questionnaire to assess patient perceptions of remote monitoring technologies in a high-volume orthopaedic clinical center. Fifty total knee arthroplasty (TKA) patients (56% female; mean age: 61 years, range: 23-89) and fifty nonoperative OA knee patients (54% female; mean age: 58 years, range: 25-89) routinely consulted in the clinic as part of their OA treatment and consented to participate in the study. Patient perceptions were compared using Pearson's chi-square analyses with a significance threshold of p < 0.05. We found that TKA patients were more receptive to the use of smartphone apps (84 vs. 60%, p = 0.008) and wearable sensors (80 vs. 48%, p < 0.001) and learning to use custom wearables (72 vs. 38%, p = 0.002) than nonoperative OA knee patients as part of their treatment. Likewise, the majority of TKA patients were willing to use the global positioning system in their postoperative technology (54 vs. 18%, p < 0.001), especially if they were only active during certain circumstances (62 vs. 24%, p < 0.001). TKA patients also expressed willingness to have their body movement (68%), balance (70%), sleep (76%), and cardiac output (80%) tracked using remote technologies. Overall, we found that TKA patients were highly receptive to using wearable technology in their treatments, whereas nonoperative OA knee patients were generally unreceptive. Our study challenges the concept that current wearable technology approaches will be generally effective as a tool to remotely monitor all patients across the OA severity landscape.