- Top of page
- Case Reports
The syndrome of pregnancy-associated osteoporosis (PAO) is a rare disorder which occurs either in late pregnancy or early post-partum period leading to fragility fracture(s), most commonly in the vertebral bodies. We presented two cases with PAO who had compression fractures at multiple levels involving five vertebrae in one case and 10 vertebrae in the other. Their spinal bone mineral density values were below −2.5 standard deviations. Anti-osteoporotic treatments with nasal calcitonin 400 IU/day, vitamin D 300.000 IU single dose, calcium 1000 mg/day, vitamin D 880 IU/day were initiated. In one case, kyphoplasty was performed by a spinal surgeon. In addition to a thoracolumbosacral orthosis, a rehabilitation program including muscle strengthening, range of motion, relaxation and weight-bearing exercises was started for both cases. These cases emphasize that all pregnant women with complaints of back/lumbar pain should be carefully evaluated.
- Top of page
- Case Reports
In this report, two cases of PAO syndrome have been presented. In one case, back pain started during the last month of pregnancy and continued till the ninth month post-partum during which she presented to our clinic. In the other patient, pain developed during the second trimester, in other words, during the sixth to seventh months of pregnancy. In both cases, fractures at multiple levels were seen on radiographies and MRI, involving five vertebrae in one case and 10 vertebrae in the other.
In a report presented by O'Sullivan et al., vertebral fractures at multiple levels were observed in 10 of 11 cases after a mean of 1 month following delivery. In nine of these cases, other underlying risk factors such as low bodyweight, smoking, family history of osteoporosis/fracture and deficiency of vitamin D were determined. However, no risk factors were found in our cases, apart from pregnancy and lactation. Furthermore, the number of fractures at multiple levels varied between two and five in the trial of O'Sullivan et al., but in one of our cases, the fractures were found in 10 vertebrae. Similarly, in a case presentation of Ofluoglu and Ofluoglu, it was reported that loss of height was observed in eight vertebrae and this patient was regarded as the first case in the published work with the highest number of fractures. Considering our second case, it may be stated that PAO may cause fractures at multiple localizations such as more than eight levels of the vertebrae.
Despite the fact that the etiopathogenesis of PAO has not been fully described, it was suggested that certain underlying factors may be responsible in the development of PAO. One of these factors is heredity, and during trials, development of PAO was more frequently observed in individuals with a positive family history. On the other hand, absence of a positive family history in either of our cases indicates that other factors play a role in the development of osteoporosis.
Another factor which is held responsible for PAO is the changes seen in bone and calcium metabolism during pregnancy and lactation. Indeed, the bone turnover significantly increases during pregnancy, especially in the third trimester; approximately 20–30 g of calcium is transferred to the baby and the mother's skeleton is under considerable risk in terms of demineralization. In spite of the fact that a number of adaptive mechanisms like increased intestinal absorption of dietary calcium, increased renal reabsorption, and additionally, mobilization of calcium from maternal skeleton develop against calcium deficiency in the mother, calcium supplementation is essential in preventing osteoporosis. The fact that supplementation of calcium and vitamin D was missing in both of our cases indicates that changes in calcium and vitamin D metabolism in pregnancy may be responsible for the etiopathogenesis of PAO. The same reason was suggested in the case with eight vertebral fractures. Authors indicate that negative calcium balance is a critical etiological factor in cases with no calcium supplementation.
Nevertheless, it is well known that PAO may develop in patients in whom calcium and vitamin D supplementation are provided during pregnancy and lactation; therefore, the above-mentioned etiological factors are not sufficient in explaining the etiopathogenesis of PAO. Further large scale trials are needed in this regard.
The clinical manifestation of PAO is severe back/lumbar pain, as it was in our cases. Unfortunately, this symptom is frequently encountered during pregnancy due to physiological reasons; hence, PAO cases are frequently missed. Indeed, a late presentation, such as 9 months after delivery in our first case, is due to this cause. Hence, it is not clear whether vertebral fractures developed during pregnancy or during lactation.
Treatment of PAO is not different from the classical treatment of osteoporosis. In various trials, antiresorptive agents such as biphosphonates and calcitonin are usually the first-line therapeutic options.[4, 5, 9-11] Among the nine cases who used biphosphonates in the trial conducted by O'Sullivan et al., spinal bone mineral density increased by 17% at the first year and by 23% at the second year. On the other hand, biphosphonates have a long-term retention rate in bone and some of them were found to cross the placenta. Animal studies showed that biphosphonates administrated during pregnancy can decrease bone length in fetuses.[12, 13] Although they do not seem to affect skeletal growth in fetuses in humans, we used nasal calcitonin, concurrently with calcium and vitamin D in both of our cases. In previous studies, it has been showed that salmon calcitonin nasal spray at a dose of 200 IU/day can reduce the risk of vertebral osteoporotic fractures by 33%.[14, 15] There is also evidence to show that calcitonin diminishes bone pain in osteoporotic vertebral fractures, which may have clinical utility in the cases with multiple fractures.
The treatment of PAO demands a combination of options, including not only therapeutic interventions, but also physiotherapy and exercises. In the acute phase following vertebral fracture, performing isometric contractions of paraspinal muscles can help to decrease post-fracture pain and edema. Ongoing chronic pain may be caused by vertebral fractures or may result from postural deformities, such as hyperkyphotic changes in the spine with inappropriate stretching of ligaments. Exercises to improve muscle strength need to focus on the back extensors. The exercises of back extensors may decrease kyphosis, lead to better dynamic static posturing, reduce pain and subsequently increase mobility and improve the patient's quality of life.[16-18] For this reason, we commenced a rehabilitation program including muscle strengthening, range of motion and relaxation exercises as well as weight-bearing exercises in both cases.
One of the other treatment options is kyphoplasty, which is usually used in acute fractures for pain relief. In the first case that was diagnosed as PAO and treated with kyphoplasty for three vertebral fractures, the authors reported that this intervention was very efficient for relief. Actually, kyphoplasty can be discussed in the management of our case. However, considering previous data, it is difficult to determine which patients with osteoporotic vertebral fractures would benefit most from kyphoplasty. Our case reported good pain relief within a few days after the operation; for this reason, it can be stated that kyphoplasty was an effective procedure for the management of her pain.
In conclusion, we described two cases with multiple vertebral fractures due to PAO. This disorder is a rare but serious problem leading to considerable morbidity in the form of pain and disability. The majority of patients present with multiple vertebral fractures like our cases. Nevertheless, it is usually unnoticed since musculoskeletal complaints – particularly back pain – are very common in pregnancy. These cases emphasized that all pregnant women with complaints of back/lumbar pain should be carefully evaluated.