[Treatment of acetabular bone defects in revision hip arthroplasty using the Revisio-System]

Bio-Activated PEEK: Promising Platforms for Improving Osteogenesis through Modulating Macrophage Polarization

The attention on orthopedic biomaterials has shifted from their direct osteogenic properties to their osteoimmunomodulation, especially the modulation of macrophage polarization. Presently, advanced technologies endow polyetheretherketone (PEEK) with good osteoimmunomodulation by modifying PEEK surface characteristics or incorporating bioactive substances with regulating macrophage polarization. Recent studies have demonstrated that the fabrication of a hydrophilic surface and the incorporation of bioactive substances into PEEK (e.g., zinc, calcium, and phosphate) are good strategies to promote osteogenesis by enhancing the polarization of M2 macrophages. Furthermore, the modification by other osteoimmunomodulatory composites (e.g., lncRNA-MM2P, IL-4, IL-10, and chitosan) and their controlled and desired release may make PEEK an optimal bio-activated implant for regulating and balancing the osteogenic system and immune system. The purpose of this review is to comprehensively evaluate the potential of bio-activated PEEK in polarizing macrophages into M2 phenotype to improve osteogenesis. For this objective, we retrieved and discussed different kinds of bio-activated PEEK regarding improving osteogenesis through modulating macrophage polarization. Meanwhile, the relevant challenges and outlook were presented. We hope that this review can shed light on the development of bio-activated PEEK with more favorable osteoimmunomodulation.

Custom Made Monoflange Acetabular Components for the Treatment of Paprosky Type III Defects

PURPOSE

Patient-specific, flanged acetabular components are used for the treatment of Paprosky type III defects during revision total hip arthroplasty (THA). This monocentric retrospective cohort study analyzes the outcome of patients treated with custom made monoflanged acetabular components (CMACs) with intra- and extramedullary iliac fixation.

METHODS

14 patients were included who underwent revision THA with CMACs for the treatment of Paprosky type III defects. Mechanism of THA failure was infection in 4 and aseptic loosening in 10 patients. Seven patients underwent no previous revision, the other seven patients underwent three or more previous revisions.

RESULTS

At a mean follow-up of 35.4 months (14-94), the revision rate of the implant was 28.3%. Additionally, one perioperative dislocation and one superficial wound infection occurred. At one year postoperatively, we found a significant improvement of the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score (p = 0.015). Postoperative radiographic analysis revealed good hip joint reconstruction with a mean leg length discrepancy of 3 mm (-8-20), a mean lateralization of the horizontal hip center of rotation of 8 mm (-8-35), and a mean proximalization of the vertical hip center of rotation of 6 mm (13-26). Radiolucency lines were present in 30%.

CONCLUSION

CMACs can be considered an option for the treatment of acetabular bone loss in revision THA. Iliac intra- and extramedullary fixation allows soft tissue-adjusted hip joint reconstruction and improves hip function. However, failure rates are high, with periprosthetic infection being the main threat to successful outcome.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation

BACKGROUND

The purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis.

MATERIAL AND METHODS

This was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases.

RESULTS

Acetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used.

CONCLUSION

The proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X‑ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

Management of pelvic discontinuity in revision arthroplasty : Cementless acetabular cup with iliac stem and cranial strap

BACKGROUND

Pelvic discontinuity causes severe destruction of the acetabular bony walls and is particularly difficult to manage. This article reports the short-term results and complications encountered in the management of loosening of the acetabular cup with pelvic discontinuity using an acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate.

MATERIAL AND METHODS

As part of this monocentric retrospective case analysis all patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup with pelvic discontinuity in this clinic from January 2016 to June 2017 were identified (n = 16). All patients underwent routine clinical and radiological follow-up. In addition, the Harris hip score (HHS) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) were evaluated as part of a 1-year follow-up.

RESULTS

All patients were treated with an acetabular revision cup of appropriate size with intramedullary iliac stem combined with an anatomical extramedullary iliac plate. On clinical follow-up at 1 year (median follow-up time 14.5 ± 3.3 months), the average HHS was 69.3 ± 14.1 and the average WOMAC was 79.3 ± 11.7. Complications were registered in 7 out of the 16 patients whereby 1 showed aseptic loosening of the revision cup, dislocations were reported in 4 cases and infections in 2 cases. In the case of the two patients with infections a Girdlestone resection arthroplasty had to be performed.

CONCLUSION

The overall complications and postoperative outcome in revision surgery after THR reported in the literature were compared to the results of this study. Compared to the results of salvage procedures using large or bipolar heads and Girdlestone resection arthroplasty, satisfactory results were obtained using the acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate.

[The minimally invasive AMIS technique for total hip replacement : Video article]

OBJECTIVE OF THE SURGERY

Minimally-invasive implantation of a total hip arthroplasty without damage to or incision of muscles.

INDICATIONS

Osteoarthritis, femoral neck fracture, general indications for total hip arthroplasty.

CONTRAINDICATIONS

Contraindications for hip arthroplasty.

SURGICAL TECHNIQUE

The surgical technique is demonstrated in detail with the help of a video of the surgical procedure, which is available online: positioning on a fracture table with a special leg holder, anterior approach between tensor fasciae latae and rectus femoris muscle, incision of hip capsule and capsular protection, osteotomy of femoral neck in situ, removal of femoral head and acetabular reaming, minimally invasive implantation of acetabular cup, release of pubofemoral ligament and-if necessary-ischiofemoral ligament, external rotation and hyperextension in leg holder with elevation of the proximal femur by a hypomochlion, femoral preparation and implantation of femoral implant, reposition, capsular suture, wound closure.

FOLLOW-UP

Weight-bearing as tolerated, free movement without limitation of range of motion.

EVIDENCE

Randomized trials and systematic reviews report faster rehabilitation with early mobilization, within the first 3 months after surgery; less postoperative pain, less muscle damage and shorter hospital stay; older patients benefit from reduced morbidity and mortality.