Biopsy of superficial bones (such as ilium, sternum, spinous process, and ribs) using a trocar needle is an image-guided diagnostic procedure wherein a small sample of bone is obtained for microscopic examination. The goal is to confirm a diagnosis of a bone disorder, determine the cause of pain or infection, investigate an abnormality seen on CT or MRI scan, or determine whether a tumour is benign or cancerous. Although a bone biopsy can be obtained from any bone in the body, doctors prefer getting biopsy samples from bones that are close to the skin surface (superficial bones) and away from large blood vessels and internal organs to minimise complications and avoid causing damage to other body parts.
A trocar is a medical device used during laparoscopic surgery. It serves as a portal for the subsequent placement of other instruments including a trephine, a cylindrical blade designed to obtain bone samples or to cut holes in bones.
Who Should Undergo and Expected Results
A biopsy of superficial bones using a trocar needle is typically performed when the results of imaging scans, such as CT scans or X-rays, reveal signs of bones abnormalities. The procedure is often instrumental in determining if the abnormalities are due to infection, cancer, or other disorders.
Conditions associated with bone disorders include:
- Coccidiomycosis and histoplasmosis (fungal infection)
- Fibroma, osteoblastoma, and osteoid osteoma (benign tumour)
- Rickets and osteomalacia (weakening of the bones due to lack of calcium or vitamin D)
- Multiple myeloma (cancer of the bone marrow that involves plasma cells)
- Mycobacteria infection (tuberculosis)
- Osteomyelitis (bone infection)
- Osteitis fibrosa (softening of the bones due to hyperparathyroidism)
- Ewing’s sarcoma and osteosarcoma (malignant bone tumour that commonly affects children)
The results of the biopsy are used to make a diagnosis or to confirm the patient’s suspected condition. Depending on the results, the doctor may request for confirmatory tests or initiate a treatment plan.
How is the Procedure Performed?
Following the administration of anaesthesia to numb the skin and subcutaneous tissue, a vertical skin incision is made on the selected biopsy site using a scalpel to separate the fascia and muscle so the bone is exposed. The pointed trocar is then inserted through the outer guide sleeve before introduced to the skin incision in order to firmly expose the bone. The trephine (a hole saw) is then inserted. Using steady increasing pressure, it is rotated until a piece of the bone is cut from the connective tissue. All the instruments are then withdrawn and the incision is closed with nylon sutures and covered with a small adhesive pad and elastic pressure dressing. The whole procedure typically lasts between 15 and 30 minutes with minimal blood loss.
Possible Risks and Complications
Although performed with anaesthetic, some patients experience sharp pain as the needle enters the bone and when the tissue sample is taken out. The biopsy site is also typically sore and tender for up to a week.
Serious complications rarely occur during a bone biopsy. However, there is a very small risk that the biopsy needle may break during the procedure and damage an organ, nerve, or blood vessel near the biopsy site. There’s also a small chance that the bone will become infected or weak at a later time, resulting in a fracture.
Carmen Georgescu et al. Value of qualitative bone histology assessment in the evaluation of subjects with primary osteoporosis. Acta Endocrinologica (Buc). 2005. 1:441-451.
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