Bone remodeling of the proximal tibia after uncemented total knee arthroplasty: secondary endpoints analyzed from a randomized trial comparing monoblock and modular tibia trays—2 year follow-up of 53 cases

Abstract

Background and purpose — Bone remodeling as a response to bone trauma, postoperative immobilization, and device-related bone reactions can lead to loss of bone stock and increase the risk of periprosthetic fracture and aseptic loosening. This study investigates the adaptive bone remodeling of the proximal tibia after uncemented total knee arthroplasty (TKA).Patients and methods — We performed a 2-year follow up of 53 patients (mean age 62 (38–70) years, 27 of whom were men, who received an uncemented TKA in a randomized controlled trial with bone mineral density (BMD) as secondary endpoint. Patients were randomized to 2 groups of either monoblock (A) or modular (B) polyethylene design. The TKAs were performed using the uncemented Zimmer Nexgen trabecular metal. Measurements of BMD were done postoperatively and after 3, 6, 12, and 24 months. BMD was measured in 3 regions of interest (ROI).Results and interpretation — In group A statistically significant changes in BMD were seen after 24 months in both the medial and lateral ROI. BMD decreased medially by 15% (p = 0.004) and laterally by 13% (p = 0.01). In group B the BMD changes were limited and after 24 months returned to the preoperative values. The differences in BMD change between groups were statistically significant in both the medial (p = 0.03) and lateral (p = 0.02) ROI. In the distal ROI we found no significant change in BMD in either group. A significantly different bone remodeling pattern of the proximal tibia was seen in the 2 groups with a higher degree of bone loss in the knees that received the monoblock polyethylene design, indicating that the flexible monoblock implant design, previously shown to improve fixation, does not decrease the bone loss of the proximal tibia.

Bone remodeling and implant migration of uncemented femoral and cemented asymmetrical tibial components in total knee arthroplasty - DXA and RSA evaluation with 2-year follow up

“…The decrease in BMD in ROI II varies from 3% [ 35 ] to 20% [ 16 ] and in ROI III from 6.5% [ 35 ] to 36.8% [ 44 ]. In our study decreases in BMD of 9.6% in ROI II and 7.2% in ROI III were observed and this corresponds well with the findings of previous studies [ 14 , 15 , 45 , 46 ].…”

“…The greatest decrease in BMD at the proximal tibia is often in ROI I (medial) and previous studies have identified a decrease with cemented tibial components between 4.4% after 1 year [ 35 ] and up to 38.6% after 2 years [ 44 ]. In our study, we identified a decrease in BMD of 9.5% in ROI I (medial) after 2 years, which is at the lower end of that found in previous studies [ 14 , 16 , 44 – 46 ]. The decrease in BMD in ROI II varies from 3% [ 35 ] to 20% [ 16 ] and in ROI III from 6.5% [ 35 ] to 36.8% [ 44 ].…”

Trabecular metal monoblock versus modular tibial trays in total knee arthroplasty: meta-analysis of randomized control trials

“…Previously, cemented modular knee arthroplasty was the most commonly used knee design, with good outcomes and survivorship. Nevertheless, osteolysis and implant loosening remain concerning when considering this design [ 24 ], and polyethylene back-side wear in the modular tibial component is a potential cause of osteolysis [ 20 ]. The introduction of the monoblock trabecular metal tibial component reduced the last two complications by enhancing bone-implant integration and omitting polyethylene wear [ 25 – 27 ].…”

“…The Digitalizer software application was used in a study [ 17 ], whose data are presented as graphs. Validated formulas [ 18 ] were used to standardize the data into means and standard deviations, and when it was impossible to convert the values or in the presence of heterogeneity, the study was excluded [ 19 , 20 ]. Dichotomous variables were analyzed using the relative risk with 95% confidence interval (CI).…”

Quantitative measurements of adaptive bone remodeling around the cemented Zimmer® segmental stem after tumor resection arthroplasty using dual-energy x-ray absorptiometry

“…Stress shielding after joint replacement surgery has previously been reported using quantitative densitometric techniques in several studies [ 9 – 11 ]. Dual-energy x-ray absorptiometry (DXA) [ 12 , 13 ] has been used extensively for quantitative and precise measurements of changes in bone mineral density (BMD) in close relation to both cemented and un-cemented orthopedic implants [ 14 – 16 ]. Only three studies [ 5 , 8 , 17 ] of partly cross-sectional design (with no immediate postoperative measurements performed) or with a very limited number of patients with inserted tumor prostheses because of malignant bone tumor resection have been published and no real prospective quantitative measurements of the adaptive bone remodeling around the fixation stems of tumor prostheses exist.…”