Percutaneous autologous bone marrow injections for delayed or non-union of bones.

1. Connolly JR, Shindell R. Percutaneous marrow injection for an ununited tibia. Nebr Med J 1986;71:105–7. 2. Connolly JF, Guse R, Tiedeman J, Dehne R. Autologous marrow injection as a substitute for operative grafting of tibial nonunions. Clin Orthop Relat Res 1991;266:259–70. 3. Galasso O, Mariconda M, Romano G, Capuano N, Romano L, Ianno B, et al. Expandable intramedullary nailing and platelet rich plasma to treat long bone non-unions. J Orthop Traumatol 2008;9:129–34. 4. Hakimi M, Jungbluth P, Thelen S, Betsch M, Linhart W, Flohe S, et al. Platelet-rich plasma combined with autologous cancellous bone: an alternative therapy for persistent non-union? [in German]. Unfallchirurg 2011;114:998–1006. 5. Griffin XL, Wallace D, Parsons N, Costa ML. Platelet rich therapies for long bone healing in adults. Cochrane Database Syst Rev 2012;7:CD009496. Authors’ reply Our responses to the queries raised are as follows: 1. Our rationale for this study was to emphasise the effectiveness of bone marrow injection for delayed/non-unions, prior to considering bone grafting. We showed that bone marrow injection worked for almost all long bones, including metacarpals. Three injections of low volume (~30 ml) were as effective as a large volume (100–150 ml) of one-off injection,1,2 and it does not dilute the concentration of osteoblasts. 2. Fracture non-unions of stable configurations were included. No or minimal mobility at the site of non-union was expected. Fractures that were very unstable or with angular deformity and shortening were excluded, as were open fractures and infected non-unions. Informed consent was obtained from each patient. 3. We were aware of the paper by Galasso et al.3 on platelet-rich plasma and the paper by Hakimi et al.4 about the supplementary role of plateletrich plasma with bone grafting for treatment of non-unions. The paper of Griffin et al.5 was not available at the time of acceptance of our paper. Despite that, studies on the use of platelet-rich plasma alone for treatment of non-unions remain limited. 4. Patients were followed up (at 4–6 weeks interval) radiographically and clinically to decide on the need to proceed to the 2nd and 3rd injections. 5. These were cases of atrophic non-union, where biology rather than mechanical instability at the fracture site was the reason for failed union. Hence, immobilising the fracture site (other than for comfort) was deemed unnecessary. Therefore, patients were allowed to mobilise as comfort allowed. 6. In our experience, bone marrow injections work well in atrophic non-unions where fracture biology was the reason for failed union. Hence, for unstable or hypertrophc non-unions they may not have any role. Fractures that are very unstable or with angular deformity and shortening constitute contraindications to this procedure.