Femoral BMD Change Following Cemented or Cementless Total Knee Arthroplasty

It has previously been reported that total knee arthroplasty (TKA) causes major femur bone loss (~18% within 1 year). Prior studies did not examine different surgical methods, such as the use of cement or robotics, in TKA. The investigators hypothesize that previously reported differences in distal femur BMD change following TKA exist between patients receiving cemented vs. cementless prostheses.

Specific Aim 1: In the entire study cohort, our primary endpoint is to estimate percent BMD change 12 and 24 months after TKA at the distal femur 25% region of interest (ROI).

Specific Aim 1a: To compare percent BMD change 12 and 24 months after TKA at the distal femur 25% ROI in cemented vs uncemented implants.

Specific Aim 1b: To compare percent BMD change 12 and 24 months after TKA at the distal femur 25% ROI in those receiving robotic vs manual implants.

Specific Aim 2: In the entire study cohort, our secondary endpoints are to estimate percent BMD change 12 and 24 months after TKA at a.) the distal femur 15% ROI and b.) a proximal tibial ROI Specific Aim 2a: To compare percent BMD change 12 and 24 months after TKA at the distal femur 15% ROI and proximal tibial ROI in cemented vs uncemented implants.

Specific Aim 2b: To compare percent BMD change 12 and 24 months after TKA at the distal femur 15% ROI and proximal tibial ROI in in those receiving robotic vs manual implants.

Exploratory Aim 1: Compare patient reported pain and function at 2 weeks, 3 months, 12 months, and 24 months;

• in those receiving cemented and cementless implants.
• in those receiving robotic vs manual implants.

Exploratory Aim 2: Evaluate leg lean mass change as measured by DXA and BIS at 2 weeks, 3 months, 12 months, and 24 months over time.

• In the entire cohort
• in those receiving cemented and cementless implants.
• in those receiving robotic vs manual implants.

Inclusion criteria

• Patients age greater than or equal to 55 years undergoing TKA with no prior total joint arthroplasty on the surgical side
• Normal BMD or osteopenia with Fracture Risk Assessment Tool (FRAX) not meeting Bone Health and Osteoporosis Foundation (BHOF) treatment recommendations, i.e., 10-year major osteoporotic fracture risk greater then or equal to 20 percent or hip fracture risk greater than or equal to 3 percent.

Exclusion criteria

• Known clinical osteoporosis defined as any one of the following:

• Hip or spine T-score less than or equal to -2.5
• History of low trauma fracture after age 50
• FRAX fracture risk calculation greater than or equal to 20 percent for major osteoporotic fracture or greater than or equal to 3 percent for hip fracture
• Prior or current use of osteoporosis medications
• Current use of systemic glucocorticoids or bone-active medications
• Rheumatoid arthritis
• Laboratory abnormalities that in the opinion of study investigators may impact bone mineral density; including calcium, creatinine, albumin and parathyroid hormone (PTH)
• 25(OH)D less than 20 ng/mL
• Not suitable for study participation due to other reasons at the investigator's discretion