Differential effect of a bone morphogenetic protein‐7 (OP‐1) on primary and revision loaded, stable implants with allograft

Abstract

Morselized impacted bone allograft is often used to reconstruct the bone bed in the revision of failed total joint arthroplasties. We hypothesized that addition of the bone morphogenetic protein OP-1 (BMP-7) to bone allograft would improve early implant fixation. We inserted one loaded 6-mm-diameter titanium implant (surrounded by 0.75-mm gap) in each medial condyle of 24 canines. On one side, the implant was inserted in a controlled experimental revision setting resembling the clinical revision situation. A primary implant was inserted on the contralateral side in a previously unoperated site. Three groups were studied: 1) allograft alone, 2) allograft + 0.4 mg OP-1, and 3) allograft + 0.8 mg OP-1. Implant fixation was evaluated at 4 weeks. Grafted implants inserted in the primary setting without OP-1 had better fixation than the grafted revision setting with or without OP-1 (significantly more bone coverage, more mineralized tissue in the gap, and better mechanical interface strength). However, grafted primary implants with OP-1 had impaired fixation compared with grafted primary implants without OP-1 (less bone coverage of the implant and less bone formation in the gap). In contrast, grafted revision implants with OP-1 significantly increased implant fixation compared with grafted revision implants without OP-1 (increased mechanical interface strength and fraction of mineralized tissue in the gap). We found no differences between the two doses in any of the settings. Addition of OP-1 to bone allografted implants may show benefit at sites with impaired bone healing capacities, such as the revision setting.

Mixing bone graft with OP-1 does not improve cup or stem fixation in revision surgery of the hip: 5-year follow-up of 10 acetabular and 11 femoral study cases and 40 control cases

“…They observed reduced ingrowth into graft mixed with OP-1 if the bone graft had also been treated with clodronate, and they concluded that resorption of the graft is necessary before any substantial new bone formation can take place. Søballe et al (2004) studied the effects of mixing allograft with OP-1 in a canine revision model. Interestingly, they found improved implant fixation without any addition of OP-1 on the side simulating a primary arthroplasty, but they found the opposite on the other side where they had created a situation that was meant to simulate a revision.…”

Locally delivered TGF-β1 and IGF-1 enhance the fixation of titanium implants: A study in dogs

“…Applications employing one growth factor have been extensively investigated (Aspenberg et al 1989, Thaller et al 1993, Lind et al 1996b, Zellin et al 1998, Laffargue et al 2000, Tielinen et al 2001, Soballe et al 2004. Applications combining two or more growth factors may be more favorable, due to their additive or synergistic effects on bone formation.…”

Do Bone Graft and Cracking of the Sclerotic Cavity Improve Fixation of Titanium and Hydroxyapatite-coated Revision Implants in an Animal Model?

“…The crack revision technique also improved the fixation of nongrafted plasmasprayed HA-coated revision implants and increased new bone formation compared with the technique of reaming where the entire bone shell was removed [2]. We also have shown HA to improve fixation in a noncrack revision experimental animal model compared with Ti6Al4V [19,23,25] and that allograft packed into a periimplant gap improves fixation in a variety of experimental and clinical settings [4,7,9,22,23,[27][28][29].…”

“…Bone from different canine donors was mixed and portioned into 1-cm 3 aliquots, stored in sterile containers, and refrozen to À20°C. During surgery, the bone allograft was inserted into the revision cavity using a specially modified curette and cylindrical impaction tool [22,23]. The procedure was repeated in approximately three to four steps until the entire revision cavity was filled with tightly packed allograft.…”