Open incisional biopsy: this method often provides a good large piece of tissue, and therefore a good chance of obtaining an accurate diagnosis. Complications such as an increased risk of haematoma formation, wound break down, infection, seeding of the incision with tumour cells and post-biopsy pathological fractures are all major disadvantages.

Closed needle or trephine biopsy: is the method of choice since although it does provide a smaller specimen, post-surgical complications are greatly reduced.  Both are easy, quick and safe and an accurate diagnosis can be made in up to 94% of cases.  Either a Jamshidi needle or Michelle trephine technique can be used.  With the Jamshidi bone marrow biopsy needle, the stylet can be inserted for guiding the needle through soft tissue, while the sharp tapered cutting edge allows entry into cortical bone.  The Jamshidi needle technique may have a lower risk of inducing pathological fractures.  The trephine method involves initial placement of a K-wire to pinpoint the biopsy site. 

Take more than one biopsy.  It is usually possible to obtain these through one skin incision by redirecting the biopsy needle or trephine.

Carefully locate the center of the lesion radiographically, and take biopsies from this area.  Measurements from prominent bony landmarks help pinpoint the proposed biopsy site.

Avoid dense, often peripheral, areas of reactive bone

Include both cortical and medullary bone in the samples: most tumours originate in the medullary cavity

Penetrate only one cortex, so as to reduce the risk of post-surgical fracture

Locate the skin incision in such a way that the biopsy tract, with any seeded tumour cells, can be completely removed if full surgical excision or amputation is later required

Locate the skin incision in such a way that it does not interfere with skin flaps that may be required after amputation.

Sample submitted is not representative of the pathological process (eg reactive bone or inflammation on the edge of an osteosarcoma)

Too few samples submitted – accuracy is greatly increased with multiple samples

Inaccurate typing of the tumour is common with poorly differentiated tumours as biopsy samples are often too small to obtain the necessary information. 

Extensively necrotic tumours may not yield diagnostic specimens

Crushing and squeezing of the biopsy sample can obscure cellular detail

Overdecalcification may obscure cellular detail, making histological evaluation difficult.

Osteosarcoma can be very variable, so that a morphological diagnosis of undifferentiated sarcoma, fibrosarcoma, chondrosarcoma, or haemangiosarcoma should be taken as a differential diagnosis to osteosarcoma until confirmation is obtained from the excisional biopsy specimen.