Periprosthetic humeral fractures associated with reverse total shoulder arthroplasty: incidence and management.

PURPOSE: The purpose of this study was to record the incidence and management of periprosthetic humeral fractures (PHF) using reverse total shoulder arthroplasty (RTSA) in our institution. METHODS: We performed a retrospective study of 203 RTSA implanted in 200 patients between 2003 and 2014. The mean follow-up was 78.82 months (range, 12-141). Mean age of the study cohort was 75.87 years (range, 44-88). There were only 25 male patients (12.5 %). We assessed the presence of periprosthetic humeral fractures studying the medical files and X-rays of all patients. RESULTS: We identified seven periprosthetic humeral fractures in 203 RTSA (3.4 %): three intra-operative (1.47 %) and four post-operative (1.97 %). The average age at the time of the fracture was 75.14 years (59-83). All patients were women (100 %). Three patients with post-operative fractures type B were treated by osteosynthesis, and one patient with post-operative fracture type A was treated conservatively. All intra-operative fractures needed cerclage wire and in one case long cemented stem. All our periprosthetic fractures healed. CONCLUSIONS: Surgical treatment with osteosynthesis in type B post-operative fractures with a stable stem is recommended. Conservative treatment is sufficient in non-displaced type A post-operative fracture. Special attention should be paid to bone quality patients using non-cemented stems in primary surgery but especially in revision shoulder surgery.

In vivo comparison of the effects of rhBMP-2 and rhBMP-4 in osteochondral tissue regeneration.

The aim of this work is to investigate the use of bone morphogenetic proteins (rhBMP-2, rhBMP-4) alone or in combination with cells delivered in a calcium alginate gel for the treatment of osteochondral defects. For this purpose, alginate gels were prepared mixing a 2% sodium alginate solution and a 200 mM calcium chloride solution (1:1). Osteochondral defects were created (4 mm wide, 5 mm deep) in the internal femoral condyle of rabbit knee and gels were directly formed into the defects. 3 months after surgery samples were harvested, gross morphology was documented and histological appearance was evaluated. The performed histological observations revealed subchondral bone regeneration in rhBMP-2 samples and moderate hyaline cartilage regeneration in rhBMP-4 samples. Thus, results indicate that alginate gel may serve as an appropriate delivery vehicle for rhBMP-2, rhBMP-4 and stromal cells. With this carrier material, differential behaviour between the evaluated proteins was observed. rhBMP-2 shows better restoration of subchondral bone in contrast to the superior efficiency of rhBMP-4 for hyaline cartilage repair.

Efficacy of supraspinatus tendon repair using mesenchymal stem cells along with a collagen I scaffold.

OBJECTIVES: Our main objective was to biologically improve rotator cuff healing in an elderly rat model using mesenchymal stem cells (MSCs) in combination with a collagen membrane and compared against other current techniques. METHODS: A chronic rotator cuff tear injury model was developed by unilaterally detaching the supraspinatus (SP) tendons of Sprague-Dawley rats. At 1 month postinjury, the tears were repaired using one of the following techniques: (a) classical surgery using sutures (n = 12), (b) type I collagen membranes (n = 15), and (c) type I collagen membranes + 1 × 106 allogeneic MSCs (n = 14). Lesion restoration was evaluated at 1, 2, and 3 months postinjury based on biomechanical criteria. Continuous variables were described using mean and standard deviation (SD). To analyse the effect of the different surgical treatments in the repaired tendons' biomechanical capabilities (maximum load, stiffness, and deformity), a two-way ANOVA model was used, introducing an interaction between such factor and time (1, 2, and 3 months postinjury). RESULTS: With regard to maximum load, we observed an almost significant interaction between treatment and time (F = 2.62, df = 4, p = 0.053). When we analysed how this biomechanical capability changed with time for each treatment, we observed that repair with OrthADAPT and MSCs was associated with a significant increase in maximum load (p = 0.04) between months 1 and 3. On the other hand, when we compared the different treatments among themselves at different time points, we observed that the repair with OrthADAPT and MSCs has associated with a significant higher maximum load, when compared with the use of suture, but only at 3 months (p = 0.014). With regard to stiffness and deformity, no significant interaction was observed (F = 1.68, df = 4, p = 0.18; F = 0.40, df = 4, p = 0.81; respectively). CONCLUSIONS: The implantation of MSCs along with a collagen I scaffold into surgically created tendon defects is safe and effective. MSCs improved the tendon's maximum load over time, indicating that MSCs could help facilitate the dynamic process of tendon repair.

Chitosan scaffolds for osteochondral tissue regeneration.

A variety of biomaterials have been introduced as potential substrates for cartilage repair. One such candidate is chitosan, which shares some characteristics with glycosaminoglycan and hyaluronic acid present in articular cartilage. Depending on chitosan source and preparation procedure, variations into its properties can be attained. Thus, the aim of this article is to study and select the most adequate chitosan properties for in vivo osteochondral tissue regeneration. In this work, chitosan molecular weight, deacetylation degree, and calcium content are tested as material variable properties. According to these properties, porous scaffolds were prepared, implanted in rabbit knee osteochondral defects, and evaluated 3 months after surgery. Results show in vitro a considerable influence of the material molecular weight on the scaffold structure. In vivo, different tissue responses were observed depending on the implanted chitosan properties. Some samples showed no material degradation, multiple adverse tissue responses, and no bone/cartilage tissue formation. Other samples showed no adverse responses and bone and cartilage tissue regeneration. The chitosan with intact mineral content (17.9 wt %), lowest molecular weight (11.49 KDa), and lowest deacetylation degree (83%) shows a well structured subchondral bone and noticeable cartilaginous tissue regeneration, being it the best one of those tested for osteochondral defect regeneration.