Table 5.
Comparison of mobile bearing knee wear assessments from other studies and our study
| Study | Bearing type | Implant | Number | In vivo duration (months)* | Assessment method | Wear rate | Notes/Findings |
|---|---|---|---|---|---|---|---|
| Kop and Swarts [24] | AP mobile | AP Glide® | 10 | 31 (10–51) | CMM, with mathematic reconstruction of unworn surfaces Visual rating of damage modes (0–3) |
0.09 mm/year 80 mm3/year (wear volume) |
Same rates for both designs No medial-lateral wear bias |
| RP | LCS® | 7 | 36 (9–70) | ||||
| Atwood et al. [1] | RP | LCS® | 100 | 41 (2–170) | Through-thickness measurement Backside surface only measurement |
0.09 mm/year 0.06 mm/year |
High initial wear rate Lower long-term rate No medial-lateral wear bias 59% had < 2 years’ duration |
| Engh et al. [18] | Mobile | LCS® MB | 23 | 29 (1–102) | Through-thickness measurement (n = 12) Visual rating of damage modes (0–3) |
0.047 mm/year | Surface damage did not reflect material lost |
| Garcia et al. [20] | RP | LCS® | 32 | 30 (0.3–191) | Visual rating of damage modes (0–3) | NA | No medial-lateral difference Damage increased with duration Damage decreased with weight and BMI Damage higher in loose knees |
| RP | Sigma® | 8 | |||||
| Kendrick et al. [23] | Mobile | Oxford® Uni | 47 | 101 (13–200) | Measured bearing thickness | 0.07 mm/year | Highest wear with extraarticular impingement |
| Lu et al. [28] | RP | LCS® | 15 | 121 (48–162) | Visual rating of damage modes (0–3) | NA | Greater damage on top surface of fixed bearings but backside of RPs RP damage did not correlate to duration or BMI RP top damage correlated to back |
| Kelly et al. [22] | RP | LCS® | 12 | 36 (10–144) | Visual rating of damage modes (0–3) | NA | Backside damage correlated to duration; top surface does not Damage does not correlate to BMI Damage higher with osteolysis |
| Sigma® | 36 | ||||||
| Current study | RP | Sigma® RP | 94 | 39 (0.4–124) | Through-thickness measurements | 0.04 mm/year | No medial wear bias; wear rate does not increase with duration No wear difference between CR and PS inserts |
* Values are expressed as mean, with range in parentheses; RP = rotating platform; CMM = coordinate measuring machine; CR = cruciate retaining; PS = posterior stabilized; NA = not available.