Bone is one of the most highly adaptive tissues in the body, possessing the capability to alter its morphology and function in response to stimuli in its surrounding environment. The ability of bone to sense and convert external mechanical stimuli into a biochemical response, which ultimately alters the phenotype and function of the cell, is described as mechanotransduction. This review aims to describe the fundamental physiology and biomechanisms that occur to induce osteogenic adaptation of a cell following application of a physical stimulus. Considerable developments have been made in recent years in our understanding of how cells orchestrate this complex interplay of processes, and have become the focus of research in osteogenesis. We will discuss current areas of preclinical and clinical research exploring the harnessing of mechanotransductive properties of cells and applying them therapeutically, both in the context of fracture healing and de novo bone formation in situations such as nonunion. Cite this article:
Bone non-union following fracture is a major cause of morbidity in combat casualties. The various clinical treatments used to prevent or treat non-union remain of limited efficacy. Research therefore continues in pre-clinical animal models in an attempt to identify an effective clinical treatment. The aim of this study was to systematically evaluate emerging pre-clinical therapies in order to rationalise priorities for translational research. The methodological protocol of this study was registered with the Collaborative Approach to Meta Analysis and Review of Animal Data from Experimental Studies (CAMARADES) and published. The review identified 3251 animal studies, 851 of which fulfilled the criteria for inclusion as detailed in the protocol. Of these, 702 of the studies described therapies that had progressed to clinical trials and were therefore excluded. The remaining 149 papers described eighteen categories of therapy that represent novel therapies yet to translate to clinical trials. These studies used a range of animal models, with heterogeneity that precluded formal synthesis and meta-analysis. This study provides a systematic evaluation of novel therapies with potential to prevent or treat non-union. It also represents a novel application of an emerging epidemiological technique to address a key priority in Combat Casualty Care research.
In the young and highly active population of military patients, femoroacetabular impingement can be a source of serious disability as well as a threat to their career. This morbidity can be treated with hip arthroscopy with debridement of cam lesion, and excision or repair of a corresponding labral tear. We report on the long term outcomes (>1 year) of 26 military cases who underwent hip arthroscopy for femoroacetabular impingement, in a single surgeon's series. Twenty two patients (four bilateral cases) underwent hip arthroscopy as a day case procedure during the period February 2013 to October 2014. Non-Arthritic Hip Scores (NAHS) were obtained from patients pre-operatively, at two months, four months and at least one year post-operatively. There was a significant improvement in NAHS at two months (75.6)(p<0.05), four months (85.1)(p<0.001) and one year (84.8)(p<0.001), compared to pre-operative NAHS (65.8). There was no significant change in NAHS beyond four months. Only three out of the 22 patients were medically discharged secondary to persistent hip symptoms. Hip arthroscopy for femoroacetabular impingement is an effective, viable procedure for military patients. Mobility, pain and function is significantly improved after surgery. This improvement is sustained in the long term up to and beyond one year.
Displaced distal radial fractures in adults are commonplace. Acknowledging that satisfactory radiographic parameters typically will beget satisfactory functional outcomes, management of these fractures includes a reduction followed by either cast/splint immobilisation or internal fixation. While we can generally rely on internal fixation to maintain the reduction the same is not true of cast immobilisation. There are, however, limited data defining the fate of a fracture reduction in those treated in a cast and up to the time of radial union. Traditional practice is to recommend six weeks of immobilisation. Our goal was to detail the radiographic patterns of change in the radiographic parameters of radial inclination (RI), ulnar variance (UV) and radial tilt (RT) over the first twelve weeks in women fifty years old and older who had sustained a displaced distal radial fracture. We examined serial standard PA and lateral distal radius radiographs of 647 women treated by closed reduction and casting for a displaced fracture of the distal radius. Measurements of RI, UV and RT from standardised radiographs were made immediately post-reduction as well as, as often as possible/feasible, at 1,2,3,6,9 and 12 weeks post fracture. All measurements were made by the senior author (accuracy range: 2 degrees for RI, 1 mm for UV and 4 degrees for RT, in 75% of cases). The primary outcome measure was the change in fracture position over time. Secondary outcomes included changes related to age group; known bone density; the relation to associated ulnar fractures; and independence of the variables of RI, UV and RT. The mean immediate post-reduction values for RI, UV and RT were 21 degrees, 1.5 mm, and −6 degrees, respectively. These all changed in the first six weeks, and did not in the second six week period. The mean change in RI was 3 degrees, 60% of the change occurring in the first week post-reduction; only 0.3 degrees of change was noted beyond three weeks. The mean UV increased by 2.2 mm over the first 6 weeks, 23% in the first week post reduction. The mean RT change of 7.7 degrees was also gradual over the first 6 weeks, with no significant change afterwards. The RI changes identified were not influenced by patient age, while UV and RT changes were greater in older groups. Those fractures of the distal radius associated with a distal ulnar shaft or neck fracture did not lose radial inclination over the study period. We have defined patterns of loss of reduction that commonly occur post reduction of a displaced distal radius fracture in women fifty years and older. Such patterns ought to guide our closed management of distal radial fractures, whether by altering the duration or method of casting. Women fifty years old and older, and physicians alike, must be advised that conventional casting post distal radial fracture reduction unreliably maintains fracture reduction.
Distal ulna fractures (DUF) are commonly associated with distal radius fractures (DRF). Recent evidence suggests that the presence and type DUFs may impact the outcomes of associated healing distal radius fractures. There is currently no standardised and validated classification system for characterising distal ulna fractures. The purpose of this study was to assess the validity of our newly created inclusive classification system for distal ulna fractures, shown to influence distal radius fracture outcomes in a previous study. A classification system for distal ulna fractures was devised based on fracture pattern and location. Type 1 fractures were those in the ulnar styloid, with type 1a involving its apex and Type 1b being in the body of the styloid; Type 2 fractures are proximal to the styloid and involve the ulnar fovea, with type 2t adopting a transverse pattern and type 2o an oblique pattern; Type 3 fractures involve the ulnar head; and type 4 fractures were those proximal to the head, with 4n being through the neck (including the physeal scar) and 4s involving the distal shaft. A questionnaire was distributed to all members of the Canadian Orthopaedics Association in both French and English, asking participants to evaluate 29 radiographic images of distal ulnar fractures. Only one answer was deemed to be correct for all but one radiograph, while for one radiograph there were three fracture types to be identified. There were 129 respondents to the questionnaire. For Type 1a fractures, of the 606 radiographs evaluated 90% answered correctly and 73% of the incorrect answers identified a Type 1b fracture pattern. For Type 1b fractures, of 600 radiographs, 83% were answered correctly, the incorrect answers including Types 1a and 2t fracture types. For Type 2t fractures, of 593 radiographs, 76% were answered correctly, and 90% of the incorrect answers identified a Type 1b fracture pattern. For Type 2o fractures, of 716 radiographs, 87% were answered correctly, and 91% of the incorrect answers were identified as either Type 4n or 2t. For Type 4n fractures, of the 465 radiographs evaluated 84% answered correctly and 80% of the incorrect answers identified a Type 4s fracture pattern. For Type 4s fractures, of the 355 radiographs evaluated 99% answered correctly and 100% of the incorrect answers identified a Type 4n fracture pattern. The results will guide the authors to further distinguish between the definitions of Types 1b and 2t, and 4n and 4s. The Canadian orthopaedic community has demonstrated how readily they can reproduce this new classification system, previously shown to be predictive of radiographic outcomes for the associated distal radius fractures. This new classification is an inclusive and simple way of characterising these fractures with high reliability. This provides treating physicians with a uniform way of describing these fractures, useful both in predicting outcomes and conducting future research.
