No abstract

The optimal release profile of locally delivered bone morphogenetic protein-2 (BMP-2) for safe and effective clinical application is unknown. In this work, the effect of differential BMP-2 release on bone formation was investigated using a novel biomaterial oligo[(polyethylene glycol) fumarate] bis[2-(methacryloyloxy) ethyl] phosphate hydrogel (OPF-BP) containing poly(lactic-co-glycolic acid) microspheres. Three composite implants with the same biomaterial chemistry and structure but different BMP-loading methods were created: BMP-2 encapsulated in microspheres (OPF-BP-Msp), BMP-2 encapsulated in microspheres and adsorbed on the phosphorylated hydrogel (OPF-BP-Cmb), and BMP-2 adsorbed on the phosphorylated hydrogel (OPF-BP-Ads). These composites were compared with the clinically used BMP-2 carrier, Infuse® absorbable collagen sponge (ACS). Differential release profiles of bioactive BMP-2 were achieved by these composites. In a rat subcutaneous implantation model, OPF-BP-Ads and ACS generated a large BMP-2 burst release (>75%), whereas a more sustained release was seen for OPF-BP-Msp and OPF-BP-Cmb (~25% and 50% burst, respectively). OPF-BP-Ads generated significantly more bone than did all other composites, and the bone formation was 12-fold higher than that of the clinically used ACS. Overall, this study clearly shows that BMP-2 burst release generates more subcutaneous bone than do sustained release in OPF-BP-microsphere composites. Furthermore, composites should not only function as a delivery vehicle but also provide a proper framework to achieve appropriate bone formation.

Background: Long-term results of the arthroscopic Bankart repair in patients older than 40 years are unknown and may be favorable in terms of postoperative glenohumeral arthritis as opposed to the long-term results of the open Latarjet procedure in patients older than 40 years. Purpose: To analyze our long-term results of the arthroscopic Bankart repair for recurrent anterior shoulder instability in patients older than 40 years of age and to compare these results with previously published long-term results of the Latarjet procedure in a cohort of similar age. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 35 consecutive patients (36 shoulders) with a mean age of 47 years (range, 40-69) at time of the arthroscopic Bankart repair were studied at a mean 13.2 years (range, 8-18) after surgery. Clinical and radiographic results were then compared with those of our previous study of 39 consecutive patients (40 shoulders) of a same age group who had been treated for the same pathology with an open Latarjet procedure. Results: Six shoulders (17%) sustained a recurrent shoulder dislocation after a mean 5.3 years; subluxation occurred in 3 shoulders (8%); and apprehension persisted in 3 shoulders (8%). Revision surgery was performed in 8 patients (22%): 2 Bankart and 6 open Latarjet. The relative preoperative Constant score and Subjective Shoulder Value were significantly improved ( P < .001) at final follow-up. Arthropathy of stabilization was advanced in the shoulders of 16 patients (47%) and had progressed by at least 2 grades in 21 patients (62%). There were significantly higher rates of redislocation and subluxation when compared with the open Latarjet procedure (9 vs 3; P = .037), and the mean final Subjective Shoulder Value was significantly lower in the Bankart group (86% vs 91%; P = .011). There were no significant differences in final advanced arthropathy (16 vs 14; P = .334) and revision rates (8 vs 7; P = .409) when compared with the Latarjet procedure. Conclusion: Arthroscopic Bankart repair for recurrent anterior shoulder instability in patients older than 40 years was associated with reliable pain relief and patient satisfaction similar to that after the open Latarjet procedure. Restoration of stability was significantly less successful and development of arthropathy no better than the open Latarjet procedure in patients older than 40 years.