Changes in Bone Mineral Density of the Femur and Tibia Before Injury to 2 Years After Anterior Cruciate Ligament Reconstruction in Division I Collegiate Athletes

Abstract

Background: Osteoarthritis (OA) is a significant long term concern after anterior cruciate ligament (ACL) reconstruction (ACLR). A low bone mineral density (BMD), particularly in the subchondral region, has been associated with the development of OA and is evident at the knee in patients long after ACLR. It is unknown if persistent BMD deficits are present in high level collegiate athletes. Purpose/Hypothesis: The purpose of this study was to evaluate bilateral changes in the BMD of the femur and tibia from before the injury to 24 months after ACLR in collegiate athletes. We hypothesized that the BMD of both the distal femur and the proximal tibia would be significantly reduced within the surgical limb initially postoperatively but return to preinjury levels by 24 months after ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 33 Division I collegiate athletes were identified between 2010 and 2021 (13 female) who underwent total body dual-energy X-ray absorptiometry (DXA) before sustaining an ACL injury. DXA was repeated at 6, 12, and 24 months after ACLR. Linear mixed effects models assessed differences in the BMD at 5%, 15%, and 50% of the femur's length (F5, F15, F50) and at 5%, 15%, and 50% of the tibia's length (T5, T15, T50) within each limb from before the injury to 24 months after ACLR, reported as Tukey-adjusted P values. Results: Compared with before the injury, the BMD at F5 of the surgical limb was reduced by 0.15 g/cm2 (SE, 0.02 g/cm2) at 6 months ( P < .001). The BMD at F15 of the surgical limb was reduced by 0.06 g/cm2 (SE, 0.01 g/cm2), 0.09 g/cm2 (SE, 0.01 g/cm2), and 0.09 g/cm2 (SE, 0.01 g/cm2) at 6, 12, and 24 months, respectively (all P < .001). The BMD at T5 of the nonsurgical limb was reduced by 0.07 g/cm2 (SE, 0.02 g/cm2) at 12 months ( P = .02) and 0.10 g/cm2 (SE, 0.02 g/cm2) at 24 months ( P = .001). The BMD at T15 of the surgical limb was reduced by 0.07 g/cm2 (SE, 0.01 g/cm2) at 6 months and 0.08 g/cm2 (SE, 0.02 g/cm2) at 12 months ( P < .001). Conclusion: BMD deficits at F15 of the surgical limb persisted out to 24 months (–7.1%) after ACLR compared with before the injury in collegiate athletes. The BMD at F5 and T15 of the surgical limb was reduced at 6 and 12 months but not at 24 months compared with preinjury levels. For the nonsurgical limb, no significant differences were detected, except for the T5 region at 12 months (–5.1%) and 24 months (–7.2%). The BMD at F50 and T50 of both limbs was not significantly different than preinjury levels at any time after ACLR.

Quadriceps Performance and Running Biomechanics Influence Femur BMD Changes after ACL Reconstruction in Collegiate Athletes

“…Persistent distal femur BMD deficits of the surgical limb have been observed after ACLR, even in patients who have returned to preinjury levels of activity (2,6). These effects are focal to the surgical limb as minimal changes in the nonsurgical limb were observed, which is consistent with prior literature (3,28).…”

“…1). This methodology has been shown to be provide reproducible ROI placement (6). The least significant change with 95% confidence interval for the F5 and F15 ROIs were found to be 0.134 and 0.079 g·cm −2 , respectively, based on a sample of healthy division I collegiate athletes (Supplemental Table 1, Supplemental Digital Content, LSC with 95% precision of the femur 5% and femur 15% ROI, http://links.lww.com/MSS/C848) (19).…”

Vitamin D status associates with skeletal muscle loss after anterior cruciate ligament reconstruction

“…Even several years after ACLR, 20-40% reductions in quadriceps strength remain [1], which associates with poorer function continuing for at least 3 years after ACLR [2, 3]. Bone mineral density (BMD) in the proximal tibia and distal femur significantly decrease within 6 months after ACLR [4, 5], and patients show significant reductions in distal femur BMD that persist for at least 2 years [5]. These strength and BMD deficits substantially increase risk for development of knee osteoarthritis [6, 7].…”

“…Even several years after ACLR, 20-40% reductions in quadriceps strength remain [1], which associates with poorer function continuing for at least 3 years after ACLR [2,3]. Bone mineral density (BMD) in the proximal tibia and distal femur significantly decrease within 6 months after ACLR [4,5],…”

“…and patients show significant reductions in distal femur BMD that persist for at least 2 years [5]. These strength and BMD deficits substantially increase risk for development of knee osteoarthritis [6,7].…”