The 2018 Mark Coventry, MD Award: Does a Ceramic Bearing Improve Pain, Function, Wear, or Survivorship of TKA in Patients Younger Than 55 Years of Age? A Randomized Trial

Total Knee Arthroplasty in Haemophilia: Long-Term Results and Survival Rate of a Modern Knee Implant with an Oxidized Zirconium Femoral Component

(1) Background: Total Knee Arthroplasty (TKA) in patient with haemophilia (PWH) has usually been performed with the use of cobalt-chrome femoral and titanium tibial components, coupled with standard polyethylene (PE) inserts. The aim of this retrospective study was to evaluate the long-term outcomes and survival rates of TKA in a series of consecutive PWH affected by severe knee arthropathy at a single institution. (2) Methods: We followed 65 patients undergoing 91 TKA, implanted using the same implant, characterized by an oxidized zirconium femoral component, coupled with a titanium tibial component, and a highly crosslinked PE. At 1, 6, and 12 months; then every year for 5 years; and finally, every other 3 years, all patients were scored for pain (VAS), function (HJHS; KSS), ROM, and radiographic changes. Kaplan-Meier survivorship curves were used to calculate the implant survival rates. (3) Results: The mean follow-up was 12.3 years (4.2-20.6). All clinical and functional scores improved significantly from preoperatively to the latest follow-up (VAS: from 6.9 to 1.3; HJHS: from 13.4 to 1.9; KSS: from 19.4 to 79; ROM: from 42.4° to 83.6°). The overall survivorship of the implants was 97.5% at the latest follow-up. (4) Conclusions: The present series showed a high survival rate of specific implants potentially linked to the choice of an oxidized zirconium coupled with a highly crosslinked PE. We promote the use of modern implants in these patients in order to ensure long-lasting positive outcomes.

Evaluation of temperature of a full ceramic total knee arthroplasty during MRI examinations

BACKGROUND

A diagnosis by magnetic resonance imaging (MRI) is often necessary before surgery of degenerative spine diseases. This can lead to a possible conflict with an inserted implant of the hip or knee. Heat generation or movement could be caused by the magnetic field. The aim of this study is to investigate temperature development in vitro in a 1.5T MRI of a ceramic knee arthroplasty.

METHODS

A full ceramic, complete metal-free non-constrained primary total knee arthroplasty is investigated. Temperature change was measured between platinum resistors before and after each MRI sequence by change of resistance. The knee implant was placed in a plastic container after the sensors were attached. Then the container was completely filled with ultrasound gel. To document any possible movement of the implant, a grid was placed under the container to document the position of the implant before and after the scans.

RESULTS

A total of four standard knee sequences were performed. The temperature at sites 1 to 5 per implant was always documented in the as-is state before MRI and then after each sequence. A total of 5 temperature measurement points were taken per implant. It was found that there were extremely small temperature variations. These were always in the range of less than 1°C. There was no case of movement of the implant triggered by the MRI scan.

CONCLUSIONS

The experimental investigations carried out here showed homogeneous results with this experimental setup. It is concluded that, at least in vitro, that this ceramic knee implant can be used in MRI examinations without heating or movement.

Cost of Aseptic Revision Total Knee Arthroplasty at a Tertiary Medical Center

BACKGROUND

Revision total knee arthroplasty (TKA) involves varying levels of case complexity and costs depending on the following: (1) number of components revised, (2) duration of operating room time, and (3) length of hospital stay. However, the cost associated with different types of aseptic TKA revisions, based on number and type of components revised, is not well described. We sought to determine differences in cost associated with different revision types, and to correlate this with average national hospital and surgeon reimbursement based on current Centers for Medicare and Medicaid Services data.

METHODS

This is a retrospective review of aseptic revision TKAs performed at a single tertiary referral center from 2015 to 2018. Patient demographic data, operating room time, and direct surgery and total hospital costs obtained from an internal accounting database (Enterprise Performance Systems, Inc) were collected. Patients were stratified by the components revised (polyethylene liner only, tibia only, femur only, or both femur and tibia). We hypothesized that direct surgery and total hospital costs would increase as case complexity increased from poly exchange to single-component revisions and both-component revisions.

RESULTS

In total, 106 patients were included (19 poly exchanges, 10 tibia-only revisions, 13 femur-only revisions, and 64 both-component revisions). Operating room time was significantly lower for poly exchange than all other groups (P < .001). Direct surgery and total hospital costs were significantly lower for poly exchange than all other groups (P < .001), and were significantly lower for tibia-only and femur-only revisions compared to both-component revisions (P < .001). Average national surgeon reimbursement by Medicare decreased as a percentage of direct surgery cost as case complexity increased from poly exchange to tibia-only, femur-only, and both-component revisions. Total hospital cost per average Diagnosis Related Group weight was lowest for single-component revisions and highest for both-component revision.

CONCLUSION

There are significant differences in cost associated with aseptic TKA revisions based on number and type of components revised. These differences may not be accurately reflected in reimbursement, and often represent a burden to those who treat complex revisions.