TRANSIENT MIGRATORY OSTEOPOROSIS

Transient osteoporosis is a rare, self-limiting syndrome, characterized by sudden onset of joint pain followed by local osteopenia after several weeks, with spontaneous healing.

EPIDEMIOLOGY:

1. Middle-aged men between 40 and 60 years old. 2. In women, it occurs almost exclusively during the third trimester of

pregnancy (mean gestational age at onset: 32 weeks) or in the early postpartum period, and tends to be commonly seen in primigravidas.

3. In a few cases, it may be bilateral or recur with a second pregnancy 4. Women to men ratio 3:1

RISK FACTORS:

1. Pregnancy2. Osteogenesis imperfect

ETIOLOGY:

No consensus in literature for the etiology.

1) NEUROGENIC THEORY (Curtiss and Kincaid) – Possible intermittent compression of the mother’s obturator nerve by the child’s head OBJECTION: Could not be experimentally reproduced in dogs.

2) THEORY OF DISUSE: Osteopenia follows the disuse caused by the patients functional impairment.

OBJECTION:

i. Demineralization takes place in a very limited joint area without affecting the rest of the extremity.

ii. Complete recovery of bone density has been documented although the involved extremity was non weight bearing.

3) NONTRAUMATIC TYPE OF REFLEX SYMPATHETIC DYSTROPHY: FAVOR: Clinical, radiological, and scintigraphic appearances of both pathologies are similar.

OBJECTION: Lacks vascular and cutaneous changes characteristic of reflex sympathetic dystrophy

4) VIRAL INFECTION:

FAVOR: Stimulate osteoclastic resorption and demineralization, generating stress fractures and pain with weight bearing.

OBJECTION: Theory has not been confirmed by further studies.

5) TRANSIENT ISCHEMIC EVENT THEORY: Produces limited cell death involving only the hematopoietic and fatty elements.Histology shows intertrabecular edema, inflammatory infiltrates, fat,bone resorption and new bone formation.

TO of the hip has been proposed as an early reversible phase of avascular osteonecrosis (AVN)

Clinical, imaging and histopathologic differences, including the gross appearance, distribution of repair tissue, and viability of bone trabeculae in the affected region, have proved they are different disorders.

PATHOPHYSIOLOGY IN PREGNANCY:

Pregnancy and lactation are stress factors on maternal calcium homeostasis.

In pregnancy, maternal placental transfer of calcium and physiological hypercalciuria

Decrease serum calcium

compensated by increasing 1,25(OH)2 D3 levels that enhance gastrointestinal calcium absorption. (but overall there is transient decrease in bone mass during pregnancy).

Transfer of calcium from serum into breast milk during lactation

Decrease serum calcium(bone loss in the initial 6 months, and recovering during the 2 years after

lactation).

In pregnant women other theories

a. damage to the joint as a result of venous stasis of pregnancy

b. damage to the lumbosacral cord as it passes across the pelvic brim

All these theories do not explain cases seen in men and non pregnant women.

CLINICAL FEATURES:

1) Sudden or progressive pain in the affected joint causing limp, without any previous trauma.

2) Pain increases while walking and standing, often improving with rest. 3) Rapid, severe osteoporosis localized to the same area.4) ROM of joint restricted and is painful in the last degrees.5) Duration of symptoms 6-9 months.6) Spontaneous involvement of other regions.

Schapira’s three phases:

Initial phase - intense pain with functional impairment, lasting approximately one month Middle phase- (one or two months) symptoms remain unchanged and marked osteopenia appears on x ray Last phase- spontaneous regression takes place, with improvement in bone density. This period lasts about four months.

JOINTS INVOLVED:

MOST COMMON - Hip, followed by knee, foot and ankle.

Transient migratory osteoporosis may present as single episode affecting only one joint or recurrent episodes that may involve two to seven joints, either successively or with overlapping. The time interval between recurrences may be short or as long as two or more years.

IMAGING:

A) RADIOGRAPHY:

i. Bone density is normal until 4-8 weeks have elapsed since the onset of

clinical symptoms. ii. Later on, a periarticular diffuse osteopenia can be seen, that in the hip

rarely affects the pelvic bone and greater trochanter.iii. Joint space remains normal, which differs from the advanced stages of AVN. iv. Bone remineralization takes place spontaneously after a 6-8 month period.

B) RADIONUCLIDE BONE-SCANNING: (High sensitivity, Low specificity)

i. A diffuse and homogeneous increase of radionuclide uptake is seen in the affected joint a few days after the onset of the symptoms (48 Hours), even before x ray changes.

ii. When symptoms diminish a gradual decrease in radionuclide uptake is detected on scintigraphy.

C) MRI:

i. 48 hours after the development of clinical symptoms and regression with clinical improvement (about 6 to 8 months later).

ii. An ill-defined area of decreased signal intensity is seen on T1-weighted images, with an area of increased signal intensity on T2-weighted images; these diffuse signal abnormalities have been attributed to bone marrow edema.

iii. In the hip, these changes mainly affect the head, neck and inter trochanteric region

DIFFERENTIAL DIAGNOSIS:

1) CRYSTAL-INDUCED ARTHROPATHY, 2) RHEUMATOID ARTHRITIS, 3) OSTEOARTHRITIS AND 4) INFECTIOUS ARTHRITIS 5) RSD6) AVN

TREATMENT:

a. Symptomatic treatment with NSAIDS, muscle relaxants, and antianxiety agents.

b. Corticosteroid therapy (15 mg prednisone daily for 4 weeks) followed by gradual tapering.

c. Physical therapy, range of motion exercises, and forced gradual weight bearing have been shown to prevent associated localized muscle atrophy.

d. Weight bearing helps promote cortical thickening giving greater architectural strength to the bones.

e. Local sympathectomy using posterior tibial nerve blocks have been helpful in conjunction with the above.

REPEAT MRI EVERY 3 MONTHS TO DETERMINE THE PROGRESSION OF OSTEOPENIA

TREATMENT OF TRANSIENT MIGRATORY OSTEOPOROSIS IN PREGNANCY:

Traumatic fractures of the femoral neck and stress fractures are most serious complications during pregnancy.TO during pregnancy has to be treated conservatively with strict recommendations to restrict weight bearing until there is radiographic evidence of reconstitution of the bone mass. A pathological fracture has to be surgically treated postpartum.