Long bone uninfected non-union: grafting techniques

Key points

Overview

This EFORT Open Reviews instructional lecture is a narrative review of bone grafting options for uninfected long bone non-unions, from autograft to cell-based therapies. Non-union is classically reported after 5–10% of long bone fractures, and the authors argue that mechanical approaches alone may still fail, so biological augmentation is needed. It is a review, not a graded guideline.

Definitions and types of non-union

Delayed union has been interpreted as absent bone bridging 3–6 months after fracture, becoming a non-union 9 months after fracture when there are no progressive healing signs over three consecutive months, although fractures unhealed for more than 6 months are often treated as non-unions. A pragmatic definition is a fracture that, in the treating physician's opinion, cannot heal without further intervention. Infected non-unions are estimated at 1–2 in 10. Atrophic non-unions mainly reflect impaired vascularity and need biological augmentation, while hypertrophic non-unions arise from insufficient stability and are treated mainly by stabilization; the authors see the two as a continuum rather than separate entities.

Structural grafts

Iliac crest autograft offers shorter healing times, better bone quality, lower material costs and no risk of disease transmission. Reported minor harvest complications include pain lasting months (5%), hematoma, seroma or superficial infection (13%) and ilio-inguinal neuralgia (2%); major ones include hernias, vascular damage, sciatic nerve injury, deep infection and iliac fracture, and failure rates up to 26% have been reported. Allografts are essentially osteoconductive, with high non-union rates at the junction with host bone, a small risk of disease transmission and a higher fracture risk in larger defects. Among synthetic substitutes, tricalcium phosphate is absorbed quickly, whereas hydroxyapatite is more stable but absorbed more slowly.

Biological grafts

Bone marrow concentration can be performed in the operating room with commercial systems that concentrate nucleated cells 4 to 7 times, and a positive relation has been shown between the number of implanted MSCs and healing of tibial non-unions; one group reported ten times fewer complications than with iliac crest harvesting. The reamer–irrigator–aspirator (RIA) system collects marrow from the diaphyseal canal; transfusion rates of up to 44% were reported initially and down to 14% later, cortical perforation and blood loss should be anticipated, and a meta-analysis found a low overall complication rate.

Expanded mesenchymal stem cells

MSCs make up only about 0.001–0.01% of nucleated marrow cells, so concentration may not provide enough. Expansion under Good Manufacturing Practice can yield up to 200 million cells from one autologous donor as an advanced therapy medicinal product, but standardization and regulatory hurdles remain, and the technique is still experimental.

Frequently asked questions

Is iliac crest bone graft still the reference standard?

Yes. The review calls it the 'gold standard' and the best available biological option for everyday surgery, while noting its limited volume, donor-site complications and failure rates of up to 26%.

Can synthetic bone substitutes be used on their own?

The authors expect a high non-union rate with substitutes alone and note that a combination with autograft at a ratio of 1:3 to 1:1 may be recommended.

Are expanded stem cells available to patients?

Not yet outside clinical trials, despite solid evidence of safety and early efficacy.

Source

Gómez-Barrena E, Ehrnthaller C. Long bone uninfected non-union: grafting techniques. EFORT Open Rev 2024;9(5):329-338. doi:10.1530/EOR-24-0032. Open access. Summary prepared by Medpresso from the original publication; it is not a substitute for the full text or for medical advice.