Ultrasonication Improves Solid Phase Synthesis of Peptides Specific for Fibroblast Growth Factor Receptor and for the Protein-Protein Interface RANK-TRAF6.

Considering our interest in the use of peptides as potential target-specific drugs or as delivery vectors of metallodrugs for various biomedical applications, it is crucial to explore improved synthetic methodologies to accomplish the highest peptide crude purity in the shortest time possible. Therefore, we compared "classical" fluorenylmethoxycarbonyl (Fmoc)-solid phase peptide synthesis (SPPS) with ultrasound(US)-assisted SPPS based on the preparation of three peptides, namely the fibroblast growth factor receptor 3(FGFR3)-specific peptide Pep1 (VSPPLTLGQLLS-NH2) and the novel peptides Pep2 (RQMATADEA-NH2) and Pep3 (AAVALLPAVLLALLAPRQMATADEA-NH2), which are being developed aimed at interfering with the intracellular protein-protein interaction(PPI) RANK-TRAF6. Our results demonstrated that US-assisted SPPS led to a 14-fold (Pep1) and 4-fold time reduction (Pep2) in peptide assembly compared to the "classical" method. Interestingly, US-assisted SPPS yielded Pep1 in higher purity (82%) than the "classical" SPPS (73%). The significant time reduction combined with high crude peptide purity attained prompted use to apply US-assisted SPPS to the large peptide Pep3, which displays a high number of hydrophobic amino acids and homooligo-sequences. Remarkably, the synthesis of this 25-mer peptide was attained during a "working day" (347 min) in moderate purity (approx. 49%). In conclusion, we have reinforced the importance of using US-SPPS towards facilitating the production of peptides in shorter time with increased efficacy in moderate to high crude purity. This is of special importance for long peptides such as the case of Pep3.

Osteosynthesis of bilateral Vancouver B2 periprosthetic femoral fracture after a bilateral RM® total hip arthroplasty at 24 and 21-years follow-up: A case report.

INTRODUCTION: The management of periprosthetic femoral fractures following hip arthroplasty is challenging, and the choice between osteosynthesis of the fracture and the revision of the prosthesis is still matter of discussion. CASE REPORT: In a 81-year-old male patient, a bilateral Vancouver type-B2 periprosthetic femoral fracture with stem loosening occurred after an accidental fall. The patient had severe medical comorbidities. The radiographic study showed a bilateral Robert Mathys cementless total hip arthroplasty at 24 and 21-years follow-up. The fractures were treated with open reduction and fixation with locking compression plates. Bicortical fixation of the loose stem was obtained by the screws of the locking plate, due to the polymeric composition of the isoelastic femoral stem. Both fractures sites were augmented with bone allografts. At follow-up period of 12 months, the X-rays showed bone union of both fractures and bilateral stable stem fixation. The patient expressed high degree of satisfaction with surgery result. DISCUSSION: The standard treatment for Vancouver type-B2 periprosthetic femoral fractures is the removal of the loose implant, fixation of the fracture, and implantation of a new revision femoral stem. However, the implantation of two long revision hip prostheses is a major operation for an older patient with precarious health condition, which can contribute to higher risk of medical and prosthetic complications. CONCLUSION: In older patients with multiple comorbidities, the use of locking plates can be a valid treatment of bilateral Vancouver B2-periprosthetic femoral fractures following RM® cementless isoelastic stem, as an alternative surgical option to femoral stem revision.

Stable fixation of a madreporic Lord femoral prosthesis at 31-year follow-up in a total hip arthroplasty: A case report.

INTRODUCTION: Lord total hip prosthesis was discontinued due to high revision rates of the smooth threaded acetabular component and negative effects of stress shielding in the proximal femur. PRESENTATION OF CASE: We report the outcome of a Lord cementless femoral stem, in a 55-year-old woman. In 1984, the patient underwent a Lord total hip arthroplasty for the treatment of advanced dysplastic osteoarthritis of the left hip. After 12 years, the cementless acetabular component of the prosthesis had been revised due to aseptic loosening. An acetabular metallic support ring and a cemented polyethylene cup were implanted, the femoral stem was not changed. The acetabular bone loss was reconstructed with morsellised cancellous bone allografts by the impacting technique. No complications were reported during the period of 19 years of the postoperative course. At the last clinical and radiological evaluations, the patient presented an asymptomatic hip and expressed high degree of satisfaction with the surgery result. The femoral stem was stable, with no measurable subsidence or radiolucent lines around the stem. DISCUSSION: Several reports have presented a high clinical success rate with the fully-porous-coated Lord femoral stem in both primary and revision cases. However, the long-term results showed a substantial rate of proximal femoral bone loss and thigh pain. CONCLUSION: In our case, the Lord stem showed an excellent long-term result at the 31-year follow-up. To our knowledge, there is no published report with results of the Lord stem longer than 26-year's follow-up.

Favorable outcome of a total hip arthroplasty with insufficient bone coverage of the roof reinforcement ring.

INTRODUCTION: Total hip arthroplasty in patients with developmental dysplasia of the hip can be a complex procedure due to acetabular and proximal femoral deformities. PRESENTATION OF CASE: A 59-year-old male patient underwent a total hip arthroplasty for the treatment of end-stage dysplastic osteoarthritis. A roof reinforcement ring, a cemented polyethylene cup, and a cementless stem were used. A portion of the superior rim of the ring was uncovered by the host bone. Morsellized autogenous femoral-head graft was impacted to fill the space between the superior rim of the ring and the superior part of the dysplastic acetabulum. At the follow-up after 5-years, the patient had no complaints and was very satisfied with the operation result. The hip radiograph revealed no signs of instability of the acetabular component, and no bone graft resorption. DISCUSSION: Favorable results were described using metal rings and conical femoral stems for the treatment of the developmental dysplasia of the hip. The superior rim of the metal ring should be against host bone for 60% of its support. Despite the suboptimal implantation of the ring compromising, apparently, mechanical stability of the arthroplasty, the outcome was favorable. CONCLUSION: This result can be supported by the good fixation of the metal ring to the pelvis with screws, the adequate orientation of both components of the total hip arthroplasty, and the bone graft incorporation.

A technique to remove a stable all-polyethylene cemented acetabular liner in revision hip arthroplasty: A case report.

INTRODUCTION: The removal of a well-fixed acetabular component in a total hip arthroplasty can cause bone fractures, excessive bleeding, as well as extended bone loss. The reimplantation of a new acetabular component may be compromised. PRESENTATION OF CASE: We report a technique using 2 cork-screws for removal a stable cemented acetabular component for the treatment of a recurrent dislocation of a cemented total hip arthroplasty, due to acetabular malposition. DISCUSSION: A diversity of approaches and tools has been used for extraction of the acetabular prosthesis. Using 2 cork-screws it is possible to create fissures and fractures into the cement mantle, and greater manual control is obtained facilitating the manipulation of the acetabular component in different directions. The cup-cemented bond can be disrupted, the host bone is preserved and the risks of complications are minimized. CONCLUSION: This technique is simple, available in any environment, reproducible, non-costly, non-timing consuming and safe.

A technique to remove a well-fixed titanium-coated RM acetabular cup in revision hip arthroplasty.

A major concern during revision hip arthroplasty is acetabular bone loss and bleeding during the extraction of well-fixed cementless acetabular cup, because no interface exists between the host bone and the cup. Forceful removal of such component using curved gouges and osteotomes often leads to extended bone loss and compromises reimplantation of a new socket. In the following case report, we removed a well-fixed polyethylene titanium-coated RM acetabular cup with 20 years of follow-up, by significant wear of the polyethylene layer. The isoelastic femoral stem was also removed by mechanical failure. We report a technique for removal of the cementless acetabular cup using powered acetabular reamers. The RM cup was sequentially reamed and when the polyethylene layer was thin enough, the remaining cup was removed easily by hand tools. The acetabular bone stock is preserved and the risks of bone fractures and bleeding are minimized. To our knowledge, these principles were applied only in cemented cups. We have used this technique in 10 cases with excellent results and no complications were noted. This is a simple, reproducible, non-costly, non-timing consuming, safe and successful technique to remove well-fixed titanium-coated RM acetabular cups.