Transient osteoporosis of the knee

Transient osteoporosis: Not just the hip to worry about

Transient osteoporosis (TO) is a clinical syndrome characterized by joint pain and the presence of bone marrow edema on magnetic resonance imaging (MRI), both of which spontaneously resolve over time. Transient osteoporosis most commonly affects the hip, but also may involve other lower extremity sites. TO likely represents a disorder that may be monoarticular or “migratory” with involvement of two or more lower extremity sites sequentially affected over a number of months. We report on two cases of transient osteoporosis, one involving the knee and one involving the hip, demonstrating the utility of serial bone mineral density measurements at both sites. Additionally, we are able to report on the microarchitectural changes seen at the distal femur on ultra-high resolution (7 T) MRI. Case #1 describes a recurrence of transient osteoporosis of the hip three years after a similar presentation at the contralateral hip and highlights the findings of rapidly changing bone mineral density in this clinical syndrome. In contrast to the spine, hip and forearm, peripheral bone density measurements at the knee are rarely reported and to our knowledge Case #2 represents the first report of transient osteoporosis of the knee demonstrating bone density findings similar to that seen in the hip. We postulate that transient osteoporosis of the knee is part of a clinical spectrum most commonly seen in the hip and one that is marked by lower extremity joint pain, bone marrow edema on MRI and transient decreases in bone mineral density all of which spontaneously resolve without sequelae.

A longitudinal study of the relationship between the status of bone marrow abnormalities and progression of knee osteoarthritis

BACKGROUND

Bone marrow abnormalities (BMAs) detected on magnetic resonance imaging (MRI) are suggested to be involved in the pathogenesis of osteoarthritis (OA), and the size of the BMAs is associated with the progression of OA. However, it still remains unclear as to whether the associations of BMA size and OA severity are observed equally or whether they differ from early to advanced stages of OA. In the present study we examined whether BMA enlargement and OA progression differed according to the severity of OA.

METHODS

One hundred and eighty patients with knee OA were enrolled in the present study, and 122 of these patients completed this study. Radiography and knee MRI were done two times in all patients, at the baseline and 6 months or later at the time of patient follow-up. The severity of OA was evaluated by radiography using the Kellgren-Lawrence (K-L) grade. The patients who showed a deterioration in the K-L grade during the follow-up examination (59/122) were defined as the deterioration group. T2-weighted fat-suppressed MR images were used to score the size of the BMAs according to the whole-organ magnetic resonance imaging score (WORMS). A new scoring system, the spacial BMA score (s-score) was defined to assess the size of the BMAs three-dimensionally.

RESULTS

In patients with K-L grade 2, the s-score changes during the follow-up period in the deterioration group were significantly increased in comparison to those in the no-change group (P = 0.04), and no significant s-score changes were observed in patients with either K-L grade 1 or 3 (P = 0.07 and 0.57) between the deterioration group and the no-change group during the follow-up examination. In patients with K-L grade 3, the s-score at the baseline in the deterioration group was higher than that in the no-change group (P = 0.05).

CONCLUSIONS

The relationship between the size and enlargement of BMAs and the progression of OA changed depending upon the severity of OA.

[Acute knee pain in pregnancy. Case report of Regional Transient Osteoporosis]

The article presents the case of a patient who after her first pregnacy, during the immediate postpartum period, suffered a femoral supracondylar fracture complicated by bone marrow edema syndrome (BMES), also known as regional temporary osteoporosis (RTO). The fracture of the distal femur was treated with an open reduction and internal fixation of the distal femur by means of a minimally invasive procedure.