Table 4.
Comparison of studies reporting changes in BMD around knee implants
| Study | Design | Number of knees | Implant | BMD measure | Followup | Results |
|---|---|---|---|---|---|---|
| Levitz et al. [13] | Prospective cohort | 31 | Cemented TKA with central stem | DPA and DEXA | 1 year in 31 patients, 7 years in 8 patients | Equal BMD at 1 year but 36.4% decrease by 8 years (p < 0.05) |
| Regnér et al. [20] | Prospective randomized | 38 | HA-coated versus fiber metal-backed cementless TKA | TEXA | 5 years | Greater BMD decrease in HA-coated TKA (36%) compared with fiber metal (15%) TKA (p = 0.02) |
| Lonner et al. [15] | Prospective cohort | 12 | Tibial component with short pegs versus long central stem cemented TKA | DEXA | 7 years | Greater BMD decrease (20%–70%) with long central stem compared with contralateral tibia (p = 0.004) than short pegs (7% loss to 27% gain) |
| Soininvaara et al. [28] | Prospective cohort | 69 | Cemented TKA with central stem | DEXA | 1 year | Medial BMD decreased 6.6% (p < 0.001), lateral BMD increased 0.4% (p = 0.2) |
| Petersen et al. [18] | Prospective randomized | 16 | HA-coated versus cast mesh cementless TKA with central stem | DEXA | 2 years | BMD decreased by 4.3% in HA-coated group and increased by 6.1% in cast mesh group (p = 0.003) |
| Abu-Rajab et al. [1] | Matched cohort | 38 | Cemented versus cementless rotating-platform TKA | DEXA | 2 years | Tibial BMD decreased up to 8.4%; no significant difference between implants |
| Munro et al. [16] | Prospective randomized | 54 | Rotating-platform versus fixed cemented TKA | qCT | 2 years | Proximal tibial cancellous BMD decreased by 12.6% (p < 0.001) and cortical by 3.6% (p < 0.001); no significant difference between implants |
| Current study | Prospective cohort | 50 | Metal-backed tibia, mobile-bearing versus all-polyethylene cemented UKA | qCT | 2 years | Mean cancellous BMD decreased 1.9% on the medial side (p = 0.111) and decreased 1.1% on the lateral side (p = 0.174); mean cortical BMD was static, decreasing 0.4% on the medial side (p = 0.193) and increasing 0.5% on the lateral side (p = 0.196); the greatest observed difference between implants for any region was 3.7% (p = 0.724) |
Results are reported for changes in tibial BMD; BMD = bone mineral density; UKA = unilateral knee arthroplasty; DPA = dual photon absorptiometry; DEXA = dual-energy x-ray absorptiometry; TEXA = triple-energy x-ray absorptiometry; qCT = quantitative CT; HA = hydroxyapatite.