3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na₂SO₄ and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

Total Hip Arthroplasty (THA) for Femoral Neck Fractures: Comparison between Standard and Dual Mobility Implants

The purpose of this retrospective study is to compare the short-term clinical and radiological results between standard and dual mobility THA for femoral neck fractures (FNF) in older patients. The hypothesis is that the dual mobility cup (DMC) has the same outcomes but a lower dislocation rate than the standard THA. The study population included 56 patients (mean age 77.7 years, range 71–85) that underwent THA for displaced FNF. Patients were divided in two comparable groups for baseline characteristics (age, sex and comorbidities): 28 patients underwent THA with a standard cup (SC) and 28 THA with DMCs. The clinical records and radiograms were reviewed to search relevant data in their postoperative history. Two postoperative dislocations occurred in the SC group and none in the DMC group. At an average follow up of 23 months (12–40), 48 patients were available for the final evaluation. The WOMAC score for all patients averaged 6.26 (0–46) and was slightly better in the DMC group (4.94 vs. 7.58; p-value = 0.41); scores were significantly better in presence of neurological comorbidities (p-value = 0.04), in the absence of diabetes (p-value = 0.04) and in the case of psychiatric disorders (p-value = 0.02). Radiographic evaluation at one year showed signs of osteointegration in 42/48 (87.5%) acetabular components (20 DMCs, 22 SC). According to our experience, DMCs proved to be a valid option for the treatment of displaced FNF in older patients, since it allowed them to achieve short-term outcomes comparable to conventional THA, while decreasing the incidence of postoperative dislocations.

Does Intraoperative Platelet-rich Plasma Improve Clinical and Structural Outcomes after Arthroscopic Repair of Isolated Tears of the Supraspinatus Tendon?

BACKGROUND

Arthroscopic cuff repair is a highly successful technique, but postoperative rehabilitation is complex and the rate of tear recurrence is not negligible. Biological augmentations have been proposed to overcome these drawbacks. The platelet-rich plasma (PRP) is a platelet-rich blood fraction that is applied on the repair site to enhance tendon healing. This study evaluates the effectiveness of PRP application in arthroscopic cuff repair.

MATERIALS AND METHODS

A prospective nonrandomized study was carried out on 22 patients undergoing arthroscopic rotator cuff repair. Only patients with isolated and repairable supraspinatus tears were included and divided into two groups: 11 patients (Group A) received intraoperative PRP and 11 patients (Group B) did not. All patients had the same rehabilitation and followup protocol. Clinical-functional parameters (visual analog score, active range of motion, University of California at Los Angeles - UCLA, Constant) were recorded at predefined intervals, and magnetic resonance imaging (MRI) was performed 1 year postoperative.

RESULTS

Only one patient of Group B did not complete the study protocol. No intraoperative or postoperative complications were observed. No differences were found in the clinical-functional parameters during the entire study. At 1 year, MRI showed 1 retear in Group A and 2 retears in Group B, but the difference was not significant.

CONCLUSIONS

The role of PRP as an adjuvant for surgical repair of rotator cuff tears is controversial. In this study, we could not demonstrate significant advantages of PRP for arthroscopic repair of isolated supraspinatus tears. The potential improvement in the structural outcome should be evaluated in the long term to justify the additional costs related to PRP application.

Shoulder arthroplasty for proximal humerus fractures in the elderly: The path from Neer to Grammont

Shoulder replacement is indicated for the surgical treatment of proximal humeral fractures in elderly patients, when severe comminution and osteoporosis jeopardize the chances of success of any fixation technique. Two different implants are available for this purpose: anatomical hemiarthroplasty (HA) and reverse total shoulder arthroplasty (RTSA). HA for fractures was popularized by Charles Neer in the ‘50s and for several decades remained the only reliable implant for these injuries. However, many authors reported inconsistent results with HA as a consequence of the high rate of tuberosity and rotator cuff failure. In 1987, Paul Grammont designed the first successful RTSA, which was the end result of a long thought process on functional surgery of the shoulder. This implant was initially used to treat cuff tear arthropathy and shoulder pseudoparalysis, but indications have gradually expanded with time. Since RTSA does not rely on a functional cuff for shoulder elevation, it was felt that results in fractures could be improved by this prosthesis. In this study, the salient features of these implants are described to understand the rationale behind both approaches and highlight their pros and cons. Several clinical studies comparing HA vs RTSA for proximal humeral fractures have been published during the last two decades. A literature review is carried out to analyze and compare outcomes of both implants, analyzing clinical results, radiographic findings and complications. The final goal is to provide an overview of the different factors to consider for making a choice between these two prostheses.