| Поясница бабушки была всегда обмотана платком. | Grandma always had a shawl wrapped around the small of her back. |
| Поясница её сильно ныла. | Her lower back ached badly. |
NB When the word поясница functions as a subject and does not have a descriptive modifier, the construction поясница у + Genitive is often preferred to (a) and (b), above: | |
| Поясница у бабушки была всегда обмотана платком. | Grandma always had a shawl wrapped around the small of her back. |