Cryotherapy

Introduction
Cryotherapy involves the use of extreme low temperatures to freeze and kill tumor cells. It has revolutionized the treatment of all kinds of cancers. This is also available as adjunctive therapy in tumors of the skeletal system. It has been shown to prevent tumors from growing in an area after it has been removed (ie. Local recurrence.)

History
Cryotherapy in musculoskeletal disease has its beginnings in the Memorial Sloan-Kettering Cancer Center in work done by Marcove et al in the seventies. This was for renal cell carcinoma (kidney cancer) that had spread to the bones (metastasized). Various workers around the world have subsequently extended it to the other tumors of the bones. 

Mechanism of action
There are various theories about the mechanism of action in crytotherapy. The temperature of the cavity is typically frozen to -80 to -200°. In this process intracellular water crystallizes and disrupts the cell from the inside. Alternatively, as is commonly known, water expands when it freezes (which is why an ice cube floats). In the process of expansion the cell ruptures.

Indications
Cryotherapy is indicated as an adjunctive procedure to reduce local recurrence in the following conditions:

  1. Benign aggressive tumors of the bone (eg. Giant cell tumors, enchondromas, low grade chondrosarcomas)
  2. Malignant metastatic tumors of the bone (eg. Renal cell carcinoma)
  3. Malignant primary tumors of the bone where margins of resection are incomplete (eg. Pelvic tumors extending into the sacrum) 


Figure 1. The technique of cryotherapy requires the cavity to be opened, burred, burned and frozen.

Method
The lesion is approached as per traditional incision generally over the site of the lesion. The lesion is opened and the contents removed or curetted (Figure 1a). The walls of the cavity are ablated with a high-speed burr and burned with an argon beam. Liquid nitrogen (Figure 1b) or a cryoprobe (Figure 1c) is inserted into the cavity and the cavity frozen (Figure 1d). Both these technologies are presently offered in our service and we have an orthopedic oncologist who is well versed in its use. Following cryotherapy, some form of implant is required within the cavity to prevent collapse of the cavity (Figure 2).


Figure 2. The resultant cavity is initially weak and is cemented (white patch) but also needs to be supported until it revitalizes using an implant like a plate (left) or rods (right).

Complications

Complications from this procedure are generally rare. These can be minimized with proper care but nevertheless still do occur even in good centers. In particular skin necrosis and fractures are uncommon complications that, though not life threatening, can be troublesome.