gms | German Medical Science

Objectives/Interrogation: There is a general consensus about the indications of a VBG, but up to now there is no evidence for technique superiority between VBGs and NVBGs.

There is still no consensus on definition of avascular necrosis of the PP: x-ray, CT scan, MRI, histology, or bleeding points at surgery.

Since some years, arthroscopy has been proposed for proximal pole nonunion, even with vascular impairment, using a spongious NVBG to fill the emptied PP.

It is well known that the metaphyseal core decompression of the distal radius can incite hyperaemia and, more recently underlined, can stimulate regional bone regeneration factors, the Bone Morphogenetic Protein-2 BMP-2 to accelerate revascularization of a necrotic lunate or even of a scaphoid avascular proximal pole non-union (APPN). Even the biophysical treatment has been recognized to be able to stimulate BMP-2.

Methods: 13 patients, between 18 and 30 years, with scaphoid APPN confirmed at surgery by the absence of bleeding points, with obvious need for volar grafting detected by CTCB, has been treated through a mini-invasive volar approach, characterized by:

• a volar NVBG, spongious or corticospongious only in case of shortening of the bone, harvested from distal radius, producing a metaphyseal core decompression.
• a stable fixation by means of an headless screw with a short leading thread, or 2 Kirschner wires, when the proximal pole, after debridment in nearly emptied, making impossible a volar screw fixation. Technical details of Kirchner wires stable application, are shown.
• an early biophysical treatment (CCEF) therapy, for at least 2 months.

Arthroscopic Bone Graft (2 pts.) is based on the same technical aspects, harvesting the spongious bone graft from the dorsal radius.

Results: Radiological union was obtained in all patients with obvious proximal pole revascularization, detected by CBCT or MRI, with gadolinium when need. Optimal ROM recovery was observed, without any functional limitation, even when Kirschner wires are still in place after many years.

Conclusions: The technical aspects of this approach are similar to the increasingly popular Arthroscopic Bone Graft in APPNs, but performing a longstanding stable fixation is easier with open surgery. In practice, as long as the proximal pole is intact and the cartilage is good it is possible to have its revascularization even with a NVBG, open or arthroscopically.

VBG still remains a correct indication after failed fixation with NVBG, but it is not an absolute indication.