Medial Tibial Stress Shielding: A Limitation of Cobalt Chromium Tibial Baseplates.
Stress shielding is a well-recognized complication associated with total knee arthroplasty. However, this phenomenon has not been thoroughly described. Specifically, no study to our knowledge has evaluated the radiographic impact of utilizing various tibial component compositions on tibial stress shielding.



We retrospectively reviewed 3 cohorts of 50 patients that had a preoperative varus deformity and were implanted with a titanium, cobalt chromium (CoCr), or an all polyethylene tibial implant. A radiographic comparative analysis was performed to evaluate the amount of medial tibial bone loss in each cohort. In addition, a clinical outcomes analysis was performed on the 3 cohorts.



The CoCr was noted to have a statistically significant increase in medial tibial bone loss compared with the other 2 cohorts. The all polyethylene cohort had a statistically significantly higher final Knee Society Score and was associated with the least amount of stress shielding.



The CoCr tray is the most rigid of 3 implants that were compared in this study. Interestingly, this cohort had the highest amount of medial tibial bone loss. In addition, 1 patient in the CoCr cohort had medial soft tissue irritation which was attributed to a prominent medial tibial tray which required revision surgery to mitigate the symptoms.
Colorado Joint Replacement, Denver, Colorado.
J Ryan
JR
Martin
Mayo Clinic, Rochester, Minnesota.
Chad D
CD
Watts
Colorado Joint Replacement, Denver, Colorado.
Daniel L
DL
Levy
Colorado Joint Replacement, Denver, Colorado; Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado; Department of Orthopedic Surgery, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia.
Raymond H
RH
Kim
D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D002857:Chromium; D002858:Chromium Alloys; D003035:Cobalt; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D012086:Reoperation; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D014025:Titanium
D002858:Chromium Alloys; D002857:Chromium; D003035:Cobalt; D020959:Polyethylene; D014025:Titanium
all polyethylene; cobalt chromium; modulus of elasticity; stress shielding; tibial baseplate; titanium