Minimally Invasive vs Open Bone Graft Harvesting

Autologous bone graft harvesting has been employed for well over 100 years in the treatment of various bone healing needs. Until relatively recent times, bone was harvested with open techniques that employed direct visualization of the bone after soft tissue incision, retraction, and commonly stripping from bony attachments. Such efforts were accompanied by relatively high complication rates and persistent donor site morbidity (including long-term pain, abdominal herniation, infection, nerve injury, etc.).

With advances in structural support from metal and plastic implants, the need for cortical cancellous bone grafts has been largely eliminated, yet the value of autologous cancellous bone in bone repair and regeneration remains superior to alternative bone graft substitutes.

Unfortunately, the stigma conferred by outdated autologous bone graft open harvesting techniques persists in the minds of many clinicians, who are unfamiliar with percutaneous autologous bone graft harvesting. Some specialists have not been sufficiently trained on the technique and are so adverse to autologous bone graft harvesting, as to be unwilling to consider the benefits cancellous autograft might have in their practices.

Percutaneous autologous cancellous bone graft harvesting can be accomplished in several forms, but like all minimally invasive surgical techniques, the benefits relative to the open version of the procedure include:

1. less time to harvest the bone and close the wound
2. reduced bleeding
3. much lower (i.e. negligible) infection rates
4. minimal immediate and long term donor site pain
5. absence of consequences of soft tissue stripping and retraction
6. reduced instrument and surgical assistance requirements

Several devices are commercially available for percutaneous autologous cancellous bone graft harvesting, including the COREX device. Unlike most of the other devices, the COREX device provides an integrated means of breaching the subcutaneous cortex, (manual trocar tip) and subsequently harvesting cancellous dowels with minimal disturbance to the architecture and osteoproliferative cells embedded within.

Open techniques require a sufficient length of incision to allow the surgeon to place retractors and visualize the bone.  Periosteal and muscle stripping along with the use of osteotomes, curettes, and gauges are commonly employed.

The COREX Device is inserted through a “stab incision” through the subcutaneous tissue to the periosteum and then advanced under manual control according to the surgeon’s understanding of the osseous location and geometry (assessed based upon palpation of bony prominences and a knowledge of anatomy). A flange stop on the trephine minimizes the risk of excessive penetration of the trocar tip. The trephine (after removal of the trocar tip) is placed through the same incision and then advanced along different axes into the same cortical entry hole. Proprioception along with instrument design provides a considerable measure of safety in advancing the trephine to varying depths within the cancellous bone. A patented capture mechanism allows for bone capture prior to removal.

In open harvesting techniques, the wound must be closed in layers, beginning with the periosteum and deep fascia. A surgical drain is commonly employed to reduce hematoma formation. At the conclusion of the procedure, syringe irrigation, and skin-only closure is all that are required after percutaneous harvesting. Infiltration of the wound with a long-acting anesthetic and the use of a collagen sponge (i.e. “Gelfoam”) to pack within the cortical defect may provide some extended post-operative local anesthesia and bleeding control.