Session VI - Upper Extremity

Fri., 10/10/03 Upper Extremity, Paper #39, 5:10 PM

*·A Comparison of rhBMP-7 (Ossigraft) and Autogenous Graft for Treatment of Metaphyseal Defects after Osteotomy of the Distal Radius

Margaret M. McQueen, MD; Carol Hajducka, RGN; Charles M. Court-Brown, MD;

Royal Infirmary of Edinburgh, Edinburgh, United Kingdom (a-Stryker Biotech)

Purpose: This study was designed to compare the healing of a metaphyseal defect in the distal radius filled with either rhBMP-7 (Ossigraft) or autogenous graft after radial osteotomy for fracture malunion.

Methods: Twenty patients were entered into the study after signing informed consent and were randomized to receive either rhBMP-7 (group 1) or autograft (group 2). There were 17 women and 3 men with an average age of 60 years (range, 35 to 78). All had a symptomatic dorsal malunion of the distal radius and were treated by one surgeon with use of a dorsal opening wedge osteotomy. Through a longitudinal dorsal incision, the dorsum of the distal radius was exposed and a saw cut made at the site of the previous fracture as far as but not dividing the volar cortex. The osteotomy was then completed by using an osteotome and a p plate applied dorsally. Patients randomized to rhBMP-7 had the resultant defect filled with the paste containing the bone morphogenic protein. Patients randomized to autograft had bone harvested from the ipsilateral iliac crest placed in the defect. Postoperatively, a cast was applied for 2 weeks and a removable splint for 4 weeks, after which the patient was encouraged to mobilize freely. Radiological review was carried out immediately postoperatively and at 2, 4, 6, 8, 12, 26, and 52 weeks with use of standardized anteroposterior and lateral views. The defect was considered filled when trabecular bone could be visualized filling the defect for at least 75% of its volume on both views. The radiographs were reviewed by an independent radiologist blinded to the treatment allocation for the assessment of defect filling. Measurements of dorsal angle, ulnar variance, and carpal alignment were made on each set of radiographs. Functional review was carried out at 6, 12, 26, and 52 weeks and included measurement of grip strength, range of movement, and pain by using an analog scale. Clinical review was carried out at each visit, at which time complications were recorded.

Results: The demographic details of the two groups were similar except that all 3 men were randomized to receive autograft. The bone defect of all patients in group 2 healed within 12 weeks. The defect of 9 of the 10 patients in group 2 healed within 12 weeks. One patient had a delayed union of the defect viewed radiologically. At 6 months, her plate was removed because of tendon irritation; she was treated by external fixation and bone grafting, and the defect subsequently united. The average dorsal angle improved from 22° preoperatively to 1° of volar tilt postoperatively with no differences between the two groups. At 1 year, the bone defect in group 1 had retained a volar tilt of 1°, but those in group 2 had collapsed into a mean volar angle of 7°. Radial shortening had improved from a mean of 3.8 mm preoperatively to 2.0 mm at 6 weeks. At 1 year this had deteriorated slightly to 2.6 mm; there were no differences between the groups. Functional outcome measures showed no differences between the two groups at any time period. Complications were similar in each group except for the presence of a donor site hematoma in 5 of the 10 patients in group 2. There was one extensor tendon rupture in each group, one neuropraxia of the dorsal branch of the radial nerve in group 1, and no cases of reflex sympathetic dystrophy.

Conclusions and Significance: Substances to promote bone healing and eliminate the need for a bone graft donor site and its attendant morbidity are becoming increasingly popular. The available published clinical evidence suggests that bone morphogenic proteins are at least equivalent to bone graft in their ability to promote union, avoid long bone nonunion, and aid union in open long bone fractures. No previous clinical study has examined the ability of these substances to induce union in metaphyseal defects. The results of this study show that rhBMP-7 is safe and effective in inducing healing of the bone defect after radial osteotomy and avoids the morbidity of an iliac crest donor site in most patients. Radiologic position was maintained up to 1 year, suggesting that the new bone formed is of adequate strength and quality.

* If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options and e-consultant or employee.