Effects of extensive circumferential periosteal stripping on the microstructure and mechanical properties of the murine femoral cortex

Condylar Reshape in Orthognathic Surgery: Morphovolumetric and Densitometric Analysis Based on 3D Imaging and Digital Workflow

Background

Condylar remodelling (CR) is a complex of phenomena that generates in response of the temporo-mandibular joint to forces and stress to maintain a morphological, functional and occlusal homeostasis. The most worrying aspect of the condylar reshape is the condylar resorption which implies fast loss of vertical dimension (>6% of pre-surgical value), mandibular retraction and open bite with preserved articular function.

Materials and Methods

Six parameters were analysed to study the condyles of twelve patients that underwent orthognathic surgery. The digital workflow was then described to make it reproducible enabling a more in-depth study of the reshaping processes that involving the condyle after a great stress like the surgery.

Results

The results of our study showed many statistically significant variations of the studied parameters. In all patients, it was noticed a decreased bone density (p = 0,002 per side).

Objectives

The aim of our study, with the aid of the contemporary 3D imaging and digital modelling and workflow technologies, is to investigate and analyse quantitatively and qualitatively the adaptative processes occurring in CR following bimaxillary repositioning. To the best of our knowledge, this is the only paper that investigates the CR considering six different variables at once.

Periosteum-Mimicking Tissue-Engineered Composite for Treating Periosteum Damage in Critical-Sized Bone Defects

The periosteum is an indispensable part of the bone that nourishes the cortical bone and acts as a repertoire of osteoprogenitor cells. Periosteal damage as a result of traumatic injuries, infections, or surgical assistance in bone surgeries is often associated with a high incidence of delayed bone healing (union or nonunion) compounded with severe pain and a risk of a secondary fracture. Developing bioengineered functional periosteal substitutes is an indispensable approach to augment bone healing. In this study, we have developed a biomimetic periosteum membrane consisting of electrospun oxygen-releasing antioxidant polyurethane on collagen membrane (polyurethane-ascorbic acid-calcium peroxide containing fibers on collagen (PUAOCC)). Further, to assist bone formation, we have developed a bioactive inorganic-organic composite cryogel (bioglass-collagen-gelatin-nanohydroxyapatite (BCGH)) as a bone substitute. In an in vitro simulated oxidative stress model, PUAOCC supported the primary periosteal cell survival. Moreover, in an in vivo, critical-sized (5.9 mm × 3.2 mm × 1.50 mm) unicortical rat tibial bone defect, implantation of PUAOCC along with the functionalized BCGH led to significant improvement in bone formation along with periosteal regeneration. The periosteal regeneration was confirmed by expression of periosteum-specific periostin and neuronal regulation-related protein markers. Our study demonstrates the development of a periosteum-mimicking membrane with promising applications to facilitate periosteal regeneration, thus assisting bone formation when used in combination with bone composites and mimicking the natural bone repair process.

Effect of periosteal resection on longitudinal bone growth in a mouse model of achondroplasia

Achondroplasia (ACH) is the most common form of short-limbed skeletal dysplasia. Patients with ACH sometimes undergo lower limb lengthening to get functional and psychological achievements. The periosteal resection (PR) is a known mechanism to increase longitudinal bone growth without osteotomy, although the results are not predictable. It could be alternative for limb lengthening in a minimally invasive technique. The purpose of this study is to evaluate the effect of PR on acceleration of bone growth in a mouse model of ACH (Fgfr3 ^ach). We performed a circumferential resection of periosteum on the proximal tibia to both wild-type and Fgfr3 ^ach mice at the age of four weeks. The second PR was done one week later in each mouse, which was subsequently sacrificed at the age of six weeks for micro-computed tomography (micro-CT) scan and histological examinations. We measured tibial bone length, bone volume, and metaphyseal trabecular bone parameters, including bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) by reconstructed micro-CT images. We also quantified the entire width of the growth plate of the proximal tibial from the sections stained with hematoxylin and eosin. Tibial bone length and bone volume of the PR side were significantly larger than the sham side in wild-type mice, while they were not statistically significant in Fgfr3 ^ach mice. The BV/TV and Tb.N in the metaphysis were significantly decreased in the PR side of both mice. The histological analysis revealed that the growth plate of the proximal tibia was significantly wider in the PR side of wild-type mice while it showed no difference in width between the PR side and the sham side in Fgfr3 ^ach mice. PR promoted longitudinal bone growth in wild-type mice, but it exhibited only a marginal effect on bone growth in Fgfr3 ^ach mice.

Induced Periosteum-Mimicking Membrane with Cell Barrier and Multipotential Stromal Cell (MSC) Homing Functionalities

The current management of critical size bone defects (CSBDs) remains challenging and requires multiple surgeries. To reduce the number of surgeries, wrapping a biodegradable fibrous membrane around the defect to contain the graft and carry biological stimulants for repair is highly desirable. Poly(ε-caprolactone) (PCL) can be utilised to realise nonwoven fibrous barrier-like structures through free surface electrospinning (FSE). Human periosteum and induced membrane (IM) samples informed the development of an FSE membrane to support platelet lysate (PL) absorption, multipotential stromal cells (MSC) growth, and the prevention of cell migration. Although thinner than IM, periosteum presented a more mature vascular system with a significantly larger blood vessel diameter. The electrospun membrane (PCL3%-E) exhibited randomly configured nanoscale fibres that were successfully customised to introduce pores of increased diameter, without compromising tensile properties. Additional to the PL absorption and release capabilities needed for MSC attraction and growth, PCL3%-E also provided a favourable surface for the proliferation and alignment of periosteum- and bone marrow derived-MSCs, whilst possessing a barrier function to cell migration. These results demonstrate the development of a promising biodegradable barrier membrane enabling PL release and MSC colonisation, two key functionalities needed for the in situ formation of a transitional periosteum-like structure, enabling movement towards single-surgery CSBD reconstruction.

Colony Formation, Migratory, and Differentiation Characteristics of Multipotential Stromal Cells (MSCs) from "Clinically Accessible" Human Periosteum Compared to Donor-Matched Bone Marrow MSCs

Periosteum is vital for fracture healing, as a highly vascular and multipotential stromal cell- (MSC-) rich tissue. During surgical bone reconstruction, small fragments of periosteum can be “clinically accessible,” yet periosteum is currently not ultilised, unlike autologous bone marrow (BM) aspirate. This study is aimed at comparing human periosteum and donor-matched iliac crest BM MSC content and characterising MSCs in terms of colony formation, growth kinetics, phenotype, cell migration patterns, and trilineage differentiation capacity. “Clinically accessible” periosteum had an intact outer fibrous layer, containing CD271+ candidate MSCs located perivasculary; the inner cambium was rarely present. Following enzymatic release of cells, periosteum formed significantly smaller fibroblastic colonies compared to BM (6.1 mm² vs. 15.5 mm², n = 4, P = 0.0006). Periosteal colonies were more homogenous in size (range 2-30 mm² vs. 2-54 mm²) and on average 2500-fold more frequent (2.0% vs. 0.0008%, n = 10, P = 0.004) relative to total viable cells. When expanded in vitro, similar growth rates up to passage 0 (P0) were seen (1.8 population doublings (PDs) per day (periosteum), 1.6 PDs per day (BM)); however, subsequently BM MSCs proliferated significantly slower by P4 (4.3 PDs per day (periosteum) vs. 9.3 PDs per day (BM), n = 9, P = 0.02). In early culture, periosteum cells were less migratory at slower speeds than BM cells. Both MSC types exhibited MSC phenotype and trilineage differentiation capacity; however, periosteum MSCs showed significantly lower (2.7-fold) adipogenic potential based on Nile red : DAPI ratios with reduced expression of adipogenesis-related transcripts PPAR-γ. Altogether, these data revealed that “clinically accessible” periosteal samples represent a consistently rich source of highly proliferative MSCs compared to donor-matched BM, which importantly show similar osteochondral capacity and lower adipogenic potential. Live cell tracking allowed determination of unique morphological and migration characteristics of periosteal MSCs that can be used for the development of novel bone graft substitutes to be preferentially repopulated by these cells.

The Biomechanical Effect of the Sagittal Split Ramus Osteotomy on the Temporomandibular Joint: Current Perspectives on the Remodeling Spectrum

The sagittal split ramus osteotomy is a key approach for treating dentofacial deformities. Although it delivers excellent results, the sagittal split ramus osteotomy is believed to induce stress to the temporomandibular joint. Potential stress inducers could be classified as intra- and postoperative factors resulting in an inflammatory response and molecular cascades, which initiate physiological remodeling. Occasionally, this process exceeds its capacity and causes pathological remodeling, through either degenerative joint disease or condylar resorption. Hard evidence on how orthognathic surgery causes inflammation and how this inflammation is linked to the spectrum of remodeling remains scarce. Current concepts on this matter are mainly based on clinical observations and molecular mechanisms are extrapolated from fundamental research in other body parts or joints. This perspective study provides an overview of current knowledge on molecular pathways and biomechanical effects in temporomandibular joint remodeling. It provides research directions that could lead to acquiring fundamental evidence of the relation of orthognathic surgery and inflammation and its role in remodeling. Performing osteotomies in animal models and identifying inflammatory mediators as well as their effect on the joint seem promising. Patients affected by pathological remodeling can also provide samples for histological as well as molecular analysis. Individual susceptibility analysis by linking certain suspect phenotypes to genetic variation could identify the cause and molecular pathway responsible for degenerative joint disease and condylar resorption, ultimately leading to clinically applicable treatment and prevention strategies.

Corrective Osteotomy of a Metacarpal Deviation Caused by Fracture in a 9-Month-Old German Fleckvieh Heifer

OBJECTIVE

To describe the surgical treatment of a metacarpal deviation caused by an untreated Salter-Harris type I fracture in a heifer.

STUDY DESIGN

Case report.

ANIMAL

9-month-old German Fleckvieh heifer.

METHODS

A closing wedge osteotomy was performed to correct deviation of fused metacarpal III and IV. A triangular bone wedge was removed and the proximal and distal fragments of the bone were brought into apposition and stabilized with an 11-hole T-plate. A full-limb cast was applied postoperative.

RESULTS

Radiographs were taken at 2, 4, and 6 weeks postoperative. No postoperative complications occurred and the heifer was discharged from the clinic 51 days after surgery. Radiographs taken 6 months after discharge showed periosteal callus formation around the closing wedge osteotomy. At 24 months postoperative, implants were intact and the heifer was in good general condition.

CONCLUSION

Closing wedge osteotomy was successfully performed in a heifer with a metacarpal deviation, correcting the malunion after a untreated Salter-Harris type I fracture. Radiographs showed evidence of osteotomy healing and the heifer had full use of the affected leg at 24 months postoperative.

Do skeletal muscle MSCs in humans contribute to bone repair? A systematic review

Mesenchymal stem cells (MSC) from bone marrow and periosteum are known to be heavily involved in fracture repair and bone regeneration is thought to be impaired when the surrounding skeletal muscle is damaged. Recent literature from mouse in vivo models suggest that cells originating from skeletal muscle can occupy a fracture callus during open fracture repair when periosteum is compromised. This systematic review set out to ascertain whether there are MSCs residing in human skeletal muscle and whether cells from human skeletal muscle are capable of forming bone in vitro and in vivo. Original journal articles were selected if they included the terms "skeletal muscle" and "mesenchymal" and used human skeletal muscle samples. Between January 2005 and September 2016, 1000 articles were screened of which, 16 studies met the inclusion criteria for this review. Human skeletal muscle derived cells (SMDC) had the MSC phenotype, positive for CD73, CD90 and CD105 and negative for CD34 and CD45 as well as the potential to differentiate into osteoblasts, chondrocytes and adipocytes in vitro. In addition, SMDC could form bone in vivo when seeded onto an osteoinductive scaffold. A subset of SMDC expressing a pericyte marker (PDGFRα) also expressed the MSC phenotype and were more osteogenic in vivo in comparison to SMDC expressing a satellite cell marker (CD56). The studies included were limited through variation of SMDC extraction methods and tissue culture conditions, which causes heterogeneuous cell cultures. Also, in vitro differentiation assays were not always carried out with bone marrow MSC positive controls. Current evidence suggests that cells with the MSC phenotype reside within human skeletal muscle and are capable of in vivo bone formation in combination with osteoinductive bone scaffolds. This has implications of future development of guided bone regeneration strategies to enhance large bone defect repair, whereby more thought into whether the fracture site should be "blocked" from the skeletal muscle should be carried out.

Marked resorption of the thumb proximal phalanx following open reduction and K-wire fixation of a phalangeal neck fracture in a child: case report

We report on a child with nonunion of a phalangeal neck fracture of the thumb following open reduction and K-wire fixation. There was progressive resorption of the proximal but not the distal fracture fragment. Successful reconstruction was obtained using a non-vascularized iliac crest bone graft.

Effects of a new piezoelectric device on periosteal microcirculation after subperiosteal preparation

INTRODUCTION

Subperiosteal preparation using a periosteal elevator leads to disturbances of local periosteal microcirculation. Soft-tissue damage can usually be considerably reduced using piezoelectric technology. For this reason, we investigated the effects of a novel piezoelectric device on local periosteal microcirculation and compared this approach with the conventional preparation of the periosteum using a periosteal elevator.

MATERIAL AND METHODS

A total of 20 Lewis rats were randomly assigned to one of two groups. Subperiosteal preparation was performed using either a piezoelectric device or a periosteal elevator. Intravital microscopy was performed immediately after the procedure as well as three and eight days postoperatively. Statistical analysis of microcirculatory parameters was performed offline using analysis of variance (ANOVA) on ranks (p<0.05).

RESULTS

At all time points investigated, intravital microscopy demonstrated significantly higher levels of periosteal perfusion in the group of rats that underwent piezosurgery than in the group of rats that underwent treatment with a periosteal elevator.

CONCLUSION

The use of a piezoelectric device for subperiosteal preparation is associated with better periosteal microcirculation than the use of a conventional periosteal elevator. As a result, piezoelectric devices can be expected to have a positive effect on bone metabolism.

Periosteum, bone's "smart" bounding membrane, exhibits direction-dependent permeability

The periosteum serves as bone's bounding membrane, exhibits hallmarks of semipermeable epithelial barrier membranes, and contains mechanically sensitive progenitor cells capable of generating bone. The current paucity of data regarding the periosteum's permeability and bidirectional transport properties provided the impetus for the current study. In ovine femur and tibia samples, the periosteum's hydraulic permeability coefficient, k, was calculated using Darcy's Law and a custom-designed permeability tester to apply controlled, volumetric flow of phosphate-buffered saline through periosteum samples. Based on these data, ovine periosteum demonstrates mechanically responsive and directionally dependent (anisotropic) permeability properties. At baseline flow rates comparable to interstitial fluid flow (0.5 µL/s), permeability is low and does not exhibit anisotropy. In contrast, at high flow rates comparable to those prevailing during traumatic injury, femoral periosteum exhibits an order of magnitude higher permeability compared to baseline flow rates. In addition, at high flow rates permeability exhibits significant directional dependence, with permeability higher in the bone to muscle direction than vice versa. Furthermore, compared to periosteum in which the intrinsic tension (pre-stress) is maintained, free relaxation of the tibial periosteum after resection significantly increases its permeability in both flow directions. Hence, the structure and mechanical stress state of periosteum influences its role as bone's bounding membrane. During periods of homeostasis, periosteum may serve as a barrier membrane on the outer surface of bone, allowing for equal albeit low quiescent molecular communication between tissue compartments including bone and muscle. In contrast, increases in pressure and baseline flow rates within the periosteum resulting from injury, trauma, and/or disease may result in a significant increase in periosteum permeability and consequently in increased molecular communication between tissue compartments. Elucidation of the periosteum's permeability properties is key to understanding periosteal mechanobiology in bone health and healing, as well as to elucidate periosteum structure and function as a smart biomaterial that allows bidirectional and mechanically responsive fluid transport.

Concise review: the periosteum: tapping into a reservoir of clinically useful progenitor cells

Elucidation of the periosteum and its regenerative potential has become a hot topic in orthopedics. Yet few review articles address the unique features of periosteum-derived cells, particularly in light of translational therapies and engineering solutions inspired by the periosteum's remarkable regenerative capacity. This review strives to define periosteum-derived cells in light of cumulative research in the field; in addition, it addresses clinical translation of current insights, hurdles to advancement, and open questions in the field. First, we examine the periosteal niche and its inhabitant cells and the key characteristics of these cells in the context of mesenchymal stem cells and their relevance for clinical translation. We compare periosteum-derived cells with those derived from the marrow niche in in vivo studies, addressing commonalities as well as features unique to periosteum cells that make them potentially ideal candidates for clinical application. Thereafter, we review the differentiation and tissue-building properties of periosteum cells in vitro, evaluating their efficacy in comparison with marrow-derived cells. Finally, we address a new concept of banking periosteum and periosteum-derived cells as a novel alternative to currently available autogenic umbilical blood and perinatal tissue sources of stem cells for today's population of aging adults who were "born too early" to bank their own perinatal tissues. Elucidating similarities and differences inherent to multipotent cells from distinct tissue niches and their differentiation and tissue regeneration capacities will facilitate the use of such cells and their translation to regenerative medicine.