New biologic effective for severe long-bone nonunions

In a small feasibility trial, five of six fractures showed regenerated bone by six months follow-up.

A new biological product has shown some efficacy in healing severe long-bone nonunion fractures in some patients who failed prior treatments,according to a press release from Aastrom Biosciences Inc., the product’s developer.

Researchers at the Hospital General de l’Hospitalet, Centro Medico Teknon and Hospital de Barcelona-SCIAS, Barcelona, Spain, conducted the feasibility trial. The study evaluated the company’s autologous bone marrow-derived cells, dubbed Tissue Repair Cells (TRCs), for the treatment of six severe long bone nonunion fractures among five patients. These fractures included three tibial, two humeral and one clavicle.

All patients underwent open reduction and internal plate fixation, replacing previous failed fixation. Surgeons mixed the TRCs with synthetic commercial matrix and an autologous fibrin. They then applied the mixture to the fracture site to aid local bone regeneration.

Anterior-posterior view of a diaphyseal distal humerus fracture case at 1 day (Figure A), 3 months (Figure C) and 12 months (Figure D) following surgery. New internal fixation had been inserted to stabilize and immobilize the bone fragments. Tissue Repair Cells (Aastrom Biosciences Inc.) and synthetic beta-TCP granules were also added as a gel with platelet-poor fibrin-enriched plasma. Researchers judged this patient to be radiographically healed and clinically functional.

COURTESY: AASTROM BIOSCIENCES

Radiographs at six months follow-up showed five of the six nonunions had regenerated bone at the fracture site. Radiographically evident callus formation was detected in five of six cases at a mean of 11 weeks postop, which appeared stable at a mean of 17 weeks. Surgeons observed no complications or treatment-related adverse effects, according to the release.

Inflammation and edema, commonly seen at the surgical site following bone grafting procedures, were either reduced or absent postoperatively in all patients, the company noted. In all cases, patients could apply weight to the treated fracture and had restored range of motion. All patients were also pain-free, and only one patient with two leg fractures remained on occupational disability due to a high level of physical effort required by his job.

“As the physician treating these patients, I am encouraged by our first use of TRCs and believe that they may represent a new tool in orthopedic medicine,” said Carlos Solano-Puerta, MD, one of the principal investigators.

“Even though our patients had severe fractures that had previously failed to heal, all exhibited good responses to the new treatment with TRCs, with the desired result of bone callus formation and bone remodeling,” he said.

Aastrom is preparing to expand the trial to implement several refinements intended to improve the use of TRCs in bone grafting. The company also initiated a related multicenter clinical trial in the United States evaluating TRCs in conjunction with an allograft bone graft matrix.

For more information:

L Orozco, L Rodriguez, C Torrico, et. al. Clinical feasibility study: the use of cultured enriched autologous bone marrow cells to treat refractory atrophic and hypotrophic nonunion fractures. Available at: http://www.aastrom.com/pdf/Whitepaper_Barcelona-051205.pdf. Accessed May 18, 2005.