Bone marrow changes related to disuse

Abstract

Objective To evaluate bone marrow changes on knee MRI in patients with 3-to-6 week long period of unloading. Materials and Methods MRI knee examinations were performed in 30 patients (14 men, 16 women, aged 20–53 years) at baseline and 5–10 weeks after immobilization of the ipsilateral lower extremity; subsets of patients were examined at additional time points. Ten volunteers (4 men, 6 women; aged 20–50) were studied as control cohort at 2 time points. Bone marrow signal abnormalities were analyzed according to 1) severity, 2) signal alteration relative to hyaline cartilage, 3) morphology, 4) increased vascularity in the knee joint and 5) T1-signal alteration. Spearman rank correlation test (SRC) and Kendall’s tau (KT) were used to compare individual scores. Results All 30 patients presented abnormal bone marrow findings after unloading, which reached a peak at 10–25 weeks (P <0.001). These findings decreased within one year (P <0.001). High scores of severity were associated with confluent and patchy patterns of bone marrow (SCR=0.923, P <0.01 and KT= 0.877 P <0.01). Conclusion Signal abnormalities of the bone marrow related to unloading are consistent findings and most prominent 10–25 weeks following immobilization when both confluent and patchy hyperintense patterns are present.

The Proximal Tibia Loses Bone Mineral Density After Anterior Cruciate Ligament Injury: Measurement Technique and Validation of a Quantitative Computed Tomography Method

“…[4][5][6][7]45 By design, the current investigation analyzed BMD before surgical intervention and was still able to detect BMD changes between injured and uninjured extremities at a mean time of 8 weeks from the initial injury to qCT scan. Although this duration may appear relatively short, Nardo et al 46 demonstrated similar timelines with bone marrow changes being evident on MRI as soon as 10 weeks following brief immobilization. In addition, van Meer et al 45 observed a difference in DEXA measured BMD between injured and contralateral knees as soon as 10.4 weeks after an ACL injury.…”

“…Although this duration may appear relatively short, Nardo et al. 46 demonstrated similar timelines with bone marrow changes being evident on MRI as soon as 10 weeks following brief immobilization. In addition, van Meer et al.…”

Bones

“…11.6 ) [ 8 , 11 ]. The peak of the signal intensity changes is between 10 and 25 weeks after injury with the abnormalities a b disappearing after 65 weeks [ 11 ]. To recognize these changes is clinically important since the original bone strength is decreased during the presence of the bone marrow changes and there is an increased risk of fractures [ 12 ].…”

Hawkins sign of the knee: Imaging appearance and clinical implication of an unusual pattern of disuse osteopenia

“…Although the pathogenesis is not entirely understood, disuse osteopenia (DO) is a known phenomenon associated with reduced weight-bearing as seen in the setting following a fracture. [ 1 ] Linear subchondral DO is a characteristic pattern commonly observed following a talus fracture. [ 2 ] This presents on radiographs as a subchondral radiolucent line, known as “Hawkins sign,” and is the result of active bone resorption which is dependent on a hyperemic state in the disused bone.…”

“…[ 2 ] This presents on radiographs as a subchondral radiolucent line, known as “Hawkins sign,” and is the result of active bone resorption which is dependent on a hyperemic state in the disused bone. [ 1 , 2 ] This hyperemia appears on magnetic resonance (MR) imaging as T2 hyperintense signal. [ 3 ] Seen approximately 6–8 weeks after trauma, it is an indicator of an intact vascular supply and an unlikely progression to avascular necrosis.…”