Age- and gender-related distribution of bone tissue of osteoporotic humeral head using computed tomography

Morphology and novel classification of proximal humeral fractures

Background: The morphology of proximal humeral fractures (PHFs) is complex, and the fixation and selection of implants need to be guided by the fracture type and classification, which requires an accurate understanding of the fracture line. This study had three purposes. 1) Define and analyze the fracture lines and morphological features of all types PHFs by three-dimensional (3D) mapping technology. 2) Determine the osteotomy position of the biomechanical model of the PHFs according to the fracture heat map. 3) Based on the analysis of the pathological morphology and distribution of a large number of consecutive cases of PHFs, propose a novel classification of PHFs. Methods: We retrospectively collected 220 cases of PHFs and generated a 3D fracture map and heat map based on computed tomography (CT) imaging. Through analysis of the fracture morphology of the 220 PHFs, a novel classification was proposed. The primary criterion for staging was the continuity between the humeral head and the greater tuberosity and lesser tuberosity, and the secondary criterion was the relationship between the humeral head segment and the humeral shaft. Results: The fracture line was primarily found around the metaphyseal zone of region of the surgical neck, with the most extensive distribution being below the larger tuberosity and on the posterior medial side of the epiphysis. We suggest that the osteotomy gap should be immediately (approximately 5-10 mm) below the lower edge of the articular surface. The most common type of fracture was type I3 (33 cases, 15.0%), followed by type IV3 fracture (23 cases, 10.4%), and type III2 fracture (22 cases, 10.0%). Interobserver and intraobserver reliability analysis for the fracture classification revealed a k value (95% confidence interval) of 0.639 (0.57-0.71) and 0.841, P < 0.01, respectively. Conclusion: In this study, the fracture line and morphological characteristics of PHFs were clarified in detail by 3D mapping technique. In addition, a new classification method was proposed by analysis of the morphological characteristics of 220 PHFs, A two-part fracture model for PHFs is also proposed.

Medialized Rip-Stop Convergence Technique for Retracted Rotator Cuff Tears

Attempts to restore the anatomical footprint during rotator cuff repair for retracted, relatively immobile tears can be difficult. In some cases, it can lead to excessive tension of the repair. Previous studies have noted improved clinical outcomes when repair tension is not excessive, and medialization of the anatomical footprint has been suggested as a technique that can help surgeons repair large, retracted tears without excessive tension and achieve improved clinical outcomes. Of note, excessive tension when restoring the rotator cuff tendon to the anatomical footprint is not limited to large, retracted tears. In some cases, restoring small- and medium-sized tears to the anatomical footprint also can lead to excessive tension. Therefore, it is not uncommon for the authors to employ some degree of footprint medialization even for repair of small- or medium-sized tears if repair to the anatomical footprint will lead to excess tension. The purpose of this article and video demonstration is to provide instruction for a reproducible rotator cuff technique using a medialized single-row rip-stop construct combined with convergence.

Risk Factors and Corresponding Management for Suture Anchor Pullout during Arthroscopic Rotator Cuff Repair

INTRODUCTION

Due to the aging of the population, the incidence of rotator cuff tears is growing. For rotator cuff repair, arthroscopic suture-anchor repair has gradually replaced open transosseous repair, so suture anchors are now considered increasingly important in rotator cuff tear reconstruction. There are some but limited studies of suture anchor pullout after arthroscopic rotator cuff repair. However, there is no body of knowledge in this area, which makes it difficult for clinicians to predict the risk of anchor pullout comprehensively and manage it accordingly.

METHODS

The literature search included rotator cuff repair as well as anchor pullout strength. A review of the literature was performed including all articles published in PubMed until September 2021. Articles of all in vitro biomechanical and clinical trial levels in English were included. After assessing all abstracts (n = 275), the full text and the bibliographies of the relevant articles were analyzed for the questions posed (n = 80). Articles including outcomes without the area of interest were excluded (n = 22). The final literature research revealed 58 relevant articles. Narrative synthesis was undertaken to bring together the findings from studies included in this review.

RESULT

Based on the presented studies, the overall incidence of anchor pullout is not low, and the incidence of intraoperative anchor pullout is slightly higher than in the early postoperative period. The risk factors for anchor pullout are mainly related to bone quality, insertion depth, insertion angle, size of rotator cuff tear, preoperative corticosteroid injections, anchor design, the materials used to produce anchors, etc. In response to the above issues, we have introduced and evaluated management techniques. They include changing the implant site of anchors, cement augmentation for suture anchors, increasing the number of suture limbs, using all-suture anchors, using an arthroscopic transosseous knotless anchor, the Buddy anchor technique, Steinmann pin anchoring, and transosseous suture repair technology.

DISCUSSION

However, not many of the management techniques have been widely used in clinical practice. Most of them come from in vitro biomechanical studies, so in vivo randomized controlled trials with larger sample sizes are needed to see if they can help patients in the long run.

Osseous microarchitecture in frequent fracture zones of the distal clavicle

Background

Fracture classifications of the distal clavicle are based on ligamentous integrity. The influence of osseous microarchitecture on fracture occurrence, morphology, and the lesion's stability has not yet been investigated. We aimed to characterize osseous microarchitecture according to common fracture classification systems based on ligamentous integrity and investigated the possible effects of age, gender, and osteoporosis in distal clavicle fractures.

Methods

N = 20 human cadaveric distal clavicles were scanned using XtremeCT with an isometric voxel size of 82 μm. In the sagittal plane, each data set was evaluated in 11 sections of approximately 7 mm thickness. Three topographic regions were defined: the bone lateral to the trapezoid (LTR), intertubercular (ITR), and medial to the conoid (MCR) ligament. Cortical bone mineral density (BMD) [mgHA/cm³] and cortical porosity (1- (BV/TV) [%]) were determined and evaluated relative to age and gender.

Results

Along the mediolateral axis, there was an >20-fold increase in median cortical porosity (P ≤ .001). There were significant differences in cortical porosity between LTR and ITR (P ≤ .001) but not between ITR and MCR (P = .09). In ITR, cortical porosity was significantly greater in >60-year-old compared to younger donors (P = .01). For BMD, there was an >2-fold decrease toward the distal apex (P ≤ .001). BMD was significantly greater in ITR compared to LTR (P ≤ .001) and in MCR compared to ITR (P = .02). In ITR and MCR, clavicles of >60-year-old donors had significantly lower BMD values compared to younger donors (P < .01). Across all 3 regions, frequency distribution of low bone mass did not significantly differ between <60-year-olds and >60-year-olds (P > .6).

Conclusion

The distal clavicle features a characteristic bony microarchitecture. The present study revealed a significant difference in bone quality of lateral, intertubercular, and medial zones of the distal clavicle and could specify target areas and strategies for surgical treatment of unstable fractures. Age, gender, and osteoporosis have a limited effect on bone quality and fracture genesis. In contrast, ligamentous quality is supposed to exert a substantial influence on fracture characteristics, especially in ITR. Fracture morphology of the distal clavicle is determined by a bony-ligamentous conjunction, which remains to be characterized.

Cetaceans Humerus Radiodensity by CT: A Useful Technique Differentiating between Species, Ecophysiology, and Age

Cetaceans are mammals that underwent a series of evolutionary adaptations to live in the aquatic environment, including morphological modifications of various anatomical structures of the skeleton and their bone mineral density (BMD); there are few studies on the latter. BMD is related to the radiodensity measured through computed tomography (CT) in Hounsfield units (HU). This work aimed to test and validate the usefulness of studying humeral bone radiodensity by CT of two cetacean species (the Atlantic spotted dolphin and the pygmy sperm whale) with different swimming and diving habits. The radiodensity was analysed at certain levels following a new protocol based on a review of previous studies. Humeral radiodensity values were related to four aspects: species, diving behaviour, swimming activity level, and age. We observed that the consistent differences in the radiodensity of the cortical bone of the distal epiphysis between animals of different life-history categories suggest that this bone portion could be particularly useful for future ontogenetic studies. Hence, this technique may be helpful in studying and comparing species with different ecophysiologies, particularly distinguishing between swimming and diving habits.

Optimizing Anchor Placement for Cone-Shaped Rotator Cuff Tears

There are various technique preferences when performing arthroscopic rotator cuff repair. Currently, most surgeons address all intra-articular pathology as well as assess the extent of a rotator cuff tear with the arthroscope in the joint prior to moving to the subacromial space, where they will initiate footprint preparation, anchor placement, and rotator cuff repair. Although this technique often yields good or at least acceptable visualization of the footprint, it does not always provide an optimal view of the medial footprint even when using a "50-yard line view" from a lateral portal. This can particularly be an issue with "cone-shaped" supraspinatus tears in which a smaller full-thickness bursal-sided tear often expands to a much larger articular-sided component. When surgeons are visualizing with the scope in the subacromial space, it is much more difficult to obtain a full appreciation of the extent of the articular-sided tear as well as optimal visualization of the medial footprint right up to the articular margin for both bone preparation and anchor placement. This article describes the benefit of keeping the arthroscope in the joint to facilitate footprint preparation and medial-row suture anchor placement prior to going to the subacromial space. This small technical modification can often offer surgeons far superior visualization of the entire greater tuberosity footprint especially when encountering a cone-shaped tear or high-grade articular-sided tear that requires repair. To further enhance viewing of the footprint with the scope intra-articularly, proficiency in using a 70° scope directed laterally will typically allow surgeons the most ideal view achievable. Once anchors are placed into the medial row, the arthroscope is inserted into the subacromial space to complete the repair.

Regional apparent density correlations within the proximal humerus

Background

Bone quality influences humeral implant selection for shoulder arthroplasty. However, little is known about how well bone near the humeral resection represents more distal cancellous bone. This investigation aimed to quantify the correlations between the apparent density of sites near the humeral head resection plane and cancellous sites throughout the metaphysis.

Methods

Using computed tomography data from 98 subjects, apparent bone density was quantified in 65 regions throughout the proximal humerus. Pearson's correlation coefficient was determined comparing the density between samples from the humeral resection and all supporting regions beneath the resection. Mean correlation coefficients were compared for (i) each sample region with all support regions, (ii) pooling all sample regions within a slice, and (iii) considering sample regions correlated with only the support regions in the same anatomic section.

Results

Stronger correlations existed for bone sampled beneath the resection (0.33 ± 0.10≤ r ≤ 0.88 ± 0.10), instead of from the resected humeral head (0.22 ± 0.10≤ r ≤ 0.66 ± 0.14). None of sample region correlated strongly with all support regions; however, strong correlations existed when sample and support regions both came from the same anatomic section.

Discussion

Assessments of cancellous bone quality in the proximal humerus should be made beneath the humeral resection not in the resected humeral head; and each anatomic quadrant should be assessed independently.

Investigating the Effects of Demographics on Shoulder Morphology and Density Using Statistical Shape and Density Modeling

A better understanding of how the shape and density of the shoulder vary among members of a population can help design more effective population-based orthopedic implants. The main objective of this study was to develop statistical shape models (SSMs) and statistical density models (SDMs) of the shoulder to describe the main modes of variability in the shape and density distributions of shoulder bones within a population in terms of principal components (PCs). These PC scores were analyzed, and significant correlations were observed between the shape and density distributions of the shoulder and demographics of the population, such as sex and age. Our results demonstrated that when the overall body sizes of male and female donors were matched, males still had, on average, larger scapulae and thicker humeral cortical bones. Moreover, we concluded that age has a weak but significant inverse effect on the density within the entire shoulder. Weak and moderate, but significant, correlations were also found between many modes of shape and density variations in the shoulder. Our results suggested that donors with bigger humeri have bigger scapulae and higher bone density of humeri corresponds with higher bone density in the scapulae. Finally, asymmetry, to some extent, was noted in the shape and density distributions of the contralateral bones of the shoulder. These results can be used to help guide the designs of population-based prosthesis components and pre-operative surgical planning.

Assessment of Bone Quality Using Radiogrammetric Parameters of Proximal Humerus in India: Defining the Osteoporotic Fracture Risk Limit Value and its Reliability

BACKGROUND

World health organization (WHO) has defined osteoporosis clinically on the basis of bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA) scan and the presence of fractures. This facility is expensive and not readily available in majority of the centers in India. The authors have attempted to study defined measurements on radiographs (radiogrammetric parameters) to diagnose osteoporosis in Indian population.

PATIENTS AND METHODS

We prospectively studied 200 proximal humerus radiographs for measuring radiogrammetric parameters and divided into Group A and B (N = 100 in each group). Group A involved patients with age < 50 years and without any illness affecting bone quality. Group B involved patients with age > 50 years and sustained acute osteoporotic fractures of distal radius/ anterior wedge vertebral fracture/intertrochanteric fracture following trivial trauma. Three parameters (cortical thickness, cortical index and deltoid tuberosity index) were measured by 3 observers at 2 different occasions.

RESULTS

The mean age of patients was 37.87 years and 58.38 years for group A and B, respectively. The 'cortical thickness' of the proximal humerus diaphysis had the mean value for Group A and B to be 0.4 ± 0.07 cm and 0.33 ± 0.06 cm respectively. The mean values for the 'cortical index' of proximal humerus came out to be 0.4 ± 0.07 for group A and 0.32 ± 0.06 for group B. The 'deltoid tuberosity index' measurements showed the mean values for group A and B were 1.81 ± 0.23 and 1.55 ± 0.16, respectively. Inter-observer reliability for single measures was excellent for deltoid tuberosity index (ICC 0.8077) and good for cortical thickness (ICC 0.7032) and cortical index (ICC 0.7357). Observer 1 had excellent intra-observer reliabilities for all the three parameters. Observer 2 and 3 had excellent reliability for deltoid tuberosity index and good intra-observer reliability for cortical thickness and cortical index. The cortical thickness had a cut off of ≤ 0.372 cm with a sensitivity of 86.02 and specificity of 82.12. The cortical index had a cut off of ≤ 0.378 with a sensitivity of 89.16 and specificity of 84.22. The deltoid tuberosity index had a cut off of ≤ 1.684 with a sensitivity of 96.61 and specificity of 84.08.

CONCLUSION

The outcome of this study is likely to help in early diagnosis of osteoporosis at the community level in the absence of DXA scan as it identifies threshold values for radiogrammetric parameters which can be a predictor of the osteoporosis. The deltoid tuberosity index was found to be the most suitable of these parameters.

Arthroscopic rotator cuff repair using a transosseous knotless anchor (ATOK)

BACKGROUND

This article reviews the clinical and radiographic outcomes in a noninferiority trial use of a transosseous knotless anchor to perform arthroscopic rotator cuff repairs in a patient cohort that have an increased incidence of osteoporosis.

METHODS

Patients aged over 60 with a documented rotator cuff tear and who failed a rehab program underwent repair using an arthroscopic transosseous knotless (ATOK) anchor. Patients were prospectively reviewed using shoulder functional assessments (age-adjusted Constant score, Oxford Shoulder Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES], visual analog scale [VAS] pain scores), and underwent preoperative as well as 1-, 3-, and 12-month postoperative magnetic resonance imaging.

RESULTS

15 patients had undergone rotator cuff repair using the ATOK and were followed for a minimum of 24 months (range 24-30 months). From preoperative to 24 months post repair, median scores improved for ASES (61-89), Oxford (26-44), Constant (62-91), and VAS Pain (5-0.5). Four patients developed a partial retear of their repair, but only 1 patient sustained a complete retear: Sugaya type I, 10; type II, 1; type III, 2; type IV, 1; and type V, 1. No anchors were displaced, and there were no osteolysis, neurologic, or technique-related complications.

CONCLUSIONS

Arthroscopic rotator cuff repairs using a transosseous knotless technique has achieved a satisfactory outcome in this group of patients, who typically have poor bone quality, increasing the risk of antegrade anchor pullout. This approach would appear to combine the potential biomechanical and biological advantages of a transosseous repair technique, with the benefits of the lower morbidity arthroscopic surgical approach.

An assessment of proximal humerus density with reference to stemless implants

BACKGROUND

Shoulder arthroplasty humeral components have undergone several generational changes, with systems now offering shorter stems and stemless options. The stemless humeral implants obtain fixation in the trabecular bone of the proximal humerus through elaborate fixation features. To optimize implant design, the regional variations in bone density within the proximal humerus should be determined. As such, the purpose of this computed tomography-based study was to map the regional variations in bone density of the proximal humerus.

METHODS

The trabecular-canal of the proximal humerus was extracted from computed tomography scans of 98 subjects and divided into 13 slices and 5 subsections (central, anterior, posterior, medial, and lateral). The average apparent density (ρ_AVG) was then quantified in each subsection of the trabecular-canal.

RESULTS

Slice depth, subsection, and gender were all significant main effects, with additional significant interactions between slice depth, subsection, and osteoarthritic condition. The slices above the resection plane had the greatest ρ_AVG, with densities decreasing down the canal. The central subsection had significantly lower ρ_AVG than the peripheral sections, and the medial subsection tended to have the highest ρ_AVG (P < .001). Furthermore, the ρ_AVG of male subjects was significantly greater than that of female subjects (P < .001).

CONCLUSIONS

The apparent density of the proximal humerus' trabecular-canal is nonuniform. This has implications for the design of stemless implants, indicating that implants seeking purchase in higher density bone should take advantage of the peripheral regions of the trabecular-canal within the first 15-20 mm beneath the humeral head resection plane.

Opportunistic Use of CT Imaging for Osteoporosis Screening and Bone Density Assessment: A Qualitative Systematic Review

BACKGROUND

The purpose of this study was to determine the clinical opportunities for the use of computed tomography (CT) imaging for inferring bone quality and to critically analyze the correlation between dual x-ray absorptiometry (DXA) and diagnostic CT as reported in the literature.

METHODS

A systematic review of the MEDLINE database was performed in February 2016 using the PubMed interface. The inclusion criteria were English language, studies performed using living human subjects, studies pertaining to orthopaedics, use of conventional diagnostic CT scans, studies that measured cancellous bone, and studies that reported Hounsfield unit (HU) measurements directly rather than a computed bone mineral density.

RESULTS

Thirty-seven studies that reported on a total of 9,109 patients were included. Of these, 10 studies correlated HU measurements of trabecular bone with DXA-based bone assessment. Reported correlation coefficients ranged between 0.399 and 0.891, and 5 of the studies reported appropriate threshold HU levels for diagnosing osteoporosis or osteopenia.

CONCLUSIONS

Direct HU measurement from diagnostic CT scans has the potential to be used opportunistically for osteoporosis screening, but in its current state it is not ready for clinical implementation. There is a lack of exchangeability among different machines that limits its broad applicability. Future research efforts should focus on identifying thresholds at specific anatomic regions in high-risk patients in order to have the greatest impact on patients. However, using diagnostic CT to infer region-specific osteoporosis could be extraordinarily valuable to orthopaedic surgeons and primary care physicians, and merits further research.

Spatial mapping of humeral head bone density

BACKGROUND

Short-stem humeral replacements achieve fixation by anchoring to the metaphyseal trabecular bone. Fixing the implant in high-density bone can provide strong fixation and reduce the risk of loosening. However, there is a lack of data mapping the bone density distribution in the proximal humerus. The aim of the study was to investigate the bone density in proximal humerus.

METHODS

Eight computed tomography scans of healthy cadaveric humeri were used to map bone density distribution in the humeral head. The proximal humeral head was divided into 12 slices parallel to the humeral anatomic neck. Each slice was then divided into 4 concentric circles. The slices below the anatomic neck, where short-stem implants have their fixation features, were further divided into radial sectors. The average bone density for each of these regions was calculated, and regions of interest were compared using a repeated-measures analysis of variance with significance set at P < .05.

RESULTS

Average apparent bone density was found to decrease from proximal to distal regions, with the majority of higher bone density proximal to the anatomic neck of the humerus (P < .05). Below the anatomic neck, bone density increases from central to peripheral regions, where cortical bone eventually occupies the space (P < .05). In distal slices below the anatomic neck, a higher bone density distribution in the medial calcar region was also observed.

CONCLUSION

This study indicates that it is advantageous with respect to implant fixation to preserve some bone above the anatomic neck and epiphyseal plate and to use the denser bone at the periphery.

A comparison of normal and osteoarthritic humeral head size and morphology

BACKGROUND

The purpose of this study was to evaluate and to compare the size and morphologic patterns among normal and osteoarthritic (OA) humeral heads.

METHODS

This comparative anatomic imaging study evaluated 150 humeral heads that were separated into 3 cohorts: normal, OA with symmetric glenoid erosion, and OA with asymmetric (type B2) glenoid erosion. Three-dimensional models were created of the humeral head from computed tomography data, and point coordinates were extracted for evaluation. Parameters measured were diameter (sphere fit and circle fit), chord distance (superoinferior and anteroposterior), and humeral head height.

RESULTS

The sphere-fit diameter of the humeral head for the entire OA cohort (100 patients; mean diameter, 59 ± 9 mm) was significantly greater (P < .001) than that of the normal cohort (50 patients; mean diameter, 49 ± 5 mm). Similarly, the humeral head circle-fit diameters in the superoinferior and anteroposterior planes were significantly greater (P < .001) in the combined OA cohorts (59 ± 9 mm and 56 ± 10 mm, respectively) compared with the normal cohort (51 ± 5 mm and 47 ± 5 mm, respectively). However, there were no significant differences (P ≥ .099) between the symmetric and asymmetric OA cohorts in sphere-fit or circle-fit diameters. The mean values of humeral head heights were not significantly different (P = .382) between cohorts, 19 ± 2 mm, 18 ± 2 mm, and 18 ± 2 mm for the normal, symmetric, and asymmetric cohorts, respectively.

DISCUSSION

Although OA humeral head morphology varies significantly from normal, it does not vary as a function of the Walch classification between symmetric and asymmetric glenoids. Understanding of the morphologic variability of the pathologic humeral head may provide insight into the pathoanatomy of osteoarthritis and the development of various erosion patterns.

Computational anatomy of the proximal humerus: An ex vivo high-resolution peripheral quantitative computed tomography study

BACKGROUND/OBJECTIVE

Spatial knowledge of the anatomy of the proximal humerus is critical for effective treatment, particularly in patients affected by fragility fractures. High-resolution peripheral quantitative computed tomography (HR-pQCT) imaging with medical image processing techniques enable three dimensional (3D) analysis of volumetric bone mineral density (vBMD) of bones of different sizes and shapes.

METHODS

To elucidate the bony anatomy and to create 3D reference data, we conducted a computerized HR-pQCT-based study in intact postmortem samples of the proximal humerus to highlight the anatomy with particular emphasis on the size, shape, and bone stock distribution pattern.Fifty-eight defrozen intact humerus samples from 28 female and 30 male donors, who were aged 61-98 years old (mean age ± standard deviation, 80.6 ± 9 years), were scanned in the proximal third using the extended standard HR-pQCT protocol. A 3D statistical bone and averaged bone density models with low, middle, and high total vBMDs were computed. We examined the 3D patterns of size and shape variations using principal component analysis, and the vBMD distributions and variabilities using volume-rendering and virtual bore probing.

RESULTS

The computer models revealed a highly variable bony anatomy in which size was the predominant variation in the first principal component (PC). In the second PC, we observed notable variabilities in the shape of the head and shaft inclination. A distinct 3D pattern of bone stock distribution was detected in which the lowest vBMD values were identified in the medullary cavity, middle values were identified in the central zone, and the highest values were identified in the cortex and humeral head-particularly in the subarticular zones. In the presence of bone loss, the vBMD values were ubiquitously decreased, but the pattern of 3D bone stock distribution was maintained.

CONCLUSION

The new anatomical 3D data that we acquired will improve the understanding of the normal bony anatomy of the proximal humerus. The extended HR-pQCT protocol and computer models may be used for other skeletal sites and used as 3D reference models that can be applied to systematically improve implant design and anchorage.

Does bone density of the greater tuberosity change in patients over 70?

INTRODUCTION

There are no published studies on bone density of the greater tuberosity of the humerus, which could influence the stability of reinsertion by suture anchors. The goal of our study was to determine the influence of age, gender and the type of tear on the quality of bone in the greater tuberosity.

METHODOLOGY

Ninety-eight patients over the age of 60 were included, 41 without a rotator cuff tear and 57 with an isolated stage 1 or 2 supraspinatus tear and fatty infiltration (FI) ≤ 2. The areas of measurement included cancellous bone located under the cortex of the greater tuberosity. Measurements were obtained either across from the tear or from the middle facet with greater tuberosity if the cuff was not torn. We measured average, maximum and minimum bone density and the standard deviation (SD) in each region with Osirix software.

RESULTS

The two groups were similar for age (73), investigated side and mean densities (0.282 g/cm(2) vs 0.210 g/cm(2)). Age over 70 was a predictive factor for osteoporosis of the greater tuberosity whether or not a rotator cuff tear was present (P<0.0001). There was less trabecular bone in women with cuff tears (P=0.009). Stage 2 cuff retraction was predictive of osteoporosis of the greater tuberosity (P=0.0001).

CONCLUSION

This is the first study in the literature to evaluate bone density of the greater tuberosity in relation to the presence or not of a rotator cuff tear in an elderly population. Female gender, age over 70 and stage 2 cuff retraction are factors responsible for osteoporosis of the greater tuberosity of the humeral head. The osteoporosis is not severe, and normally the quality of bone of the greater tuberosity should not limit stability of suture anchors.

LEVEL OF EVIDENCE

3.

Three-dimensional analyses of proximal humeral fractures using computed tomography with multiplanar reconstruction: early stability of fixation after osteosynthesis in relation to preoperative bone quality

The purpose of this study was to evaluate the relationship between the bone quality of the humeral head measured by CT multiplanar reconstruction images (MPR) and the stability of nail or plate fixation and to compare the clinical outcomes of these procedures in patients with proximal humeral fractures. Thirty-six consecutive patients (nail group: n = 18, plate group: n = 18) were investigated. In nail group, 14 cases were classified as two-part fractures, three cases were classified as three-part fractures and one case was classified as four-part fractures. In plate group, three cases were classified as two-part fractures, nine cases were classified as three-part fractures and six cases were classified as four-part fractures. Both clinical and radiological outcomes were assessed. In addition, the percentage of trabecular bone volume of the humeral head was calculated using preoperative CT-MPR images. Three patients in the nail group underwent reoperation. In contrast, no patients in the plate group underwent reoperation. In nail group, six of 18 (33%) patients demonstrated poor results (three underwent reoperation, and three had varus displacements >10º) and had bone volume percentages (axial image) that were significantly lower than those observed in the patients with good results. The cutoff point of trabecular bone volume required to obtain satisfactory results after surgical treatment using intramedullary nail was 78%. The results of this study suggest that the bone volume of the humeral head calculated using CT-MPR images provides useful information, in addition to the type of fracture, when selecting fixation devices for osteosynthesis of proximal humeral fracture.

Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a finite element analysis

PURPOSE. To measure the effect of void-filling calcium triphosphate cement on the loads at the implant-bone interface of a proximal humeral fracture osteosynthesis using a finite element analysis. METHODS. Finite element models of a 3-part proximal humeral fracture fixed with a plate with and without calcium triphosphate cement augmentation were generated from a quantitative computed tomography dataset of an intact proximal humerus. Material properties were assigned to bone fragments using published expressions relating Young's modulus to local Hounsfield number. Boundary conditions were then applied to the model to replicate the physiological loads. The effect of void-filling calcium triphosphate cement was analysed. RESULTS. When the void was filled with calcium triphosphate cement, the pressure gradient of the bone surrounding the screws in the medial fracture fragment decreased 97% from up to 21.41 to 0.66 MPa. Peak pressure of the fracture planes decreased 95% from 6.10 to 0.30 MPa and occurred along the medial aspect. The mean stress in the screw locking mechanisms decreased 78% from 71.23 to 15.92 MPa. The angled proximal metaphyseal screw had the highest stress. CONCLUSION. Augmentation with calcium triphosphate cement improves initial stability and reduces stress on the implant-bone interface.

Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a cadaveric biomechanical study

PURPOSE. To evaluate the effect of filling a central humeral bone void with calcium triphosphate cement on the strength and stability of an osteosynthesis in elderly cadavers. METHODS. 14 fresh cadaveric shoulder specimens obtained from 11 donors (mean age, 91.5 years; mean body weight, 61 kg) were divided into 2 age- and sex-matched groups. A standardised 3-part proximal humeral fracture with a central bone void was created in each specimen. Each specimen was reduced and fixed with a locking plate. In half the specimens the central bone void was packed with calcium triphosphate cement. The intra-fragmentary motion and the load and mode of failure were recorded. RESULTS. Respectively in the test group and controls, the intra-fragmentary motion was 1.0 and 6.4 mm, and the peak displacement at the 500 N load was 1.8 and 9.1 mm. The Cohen's d was 1.6 to 2.7 for all load steps, indicating a large effect of the calcium triphosphate cement on strength and stability. The mean difference in the failure load was 300 N (p<0.05). CONCLUSION. Construct stability and failure load improved significantly when the central humeral bone void was filled with calcium triphosphate cement.

Stress distribution inside bone after suture anchor insertion: simulation using a three-dimensional finite element method

PURPOSE

To define stress distribution patterns inside a bone around suture anchors inserted at different angles using a three-dimensional finite element (FE) method.

METHODS

An isotropic cube model (Young's modulus, 1,380 MPa; Poisson's ratio, 0.3) was designed on a computer to standardize analysis conditions. A virtual Twinfix anchor was inserted into the cube at two different angles (45° and 90°) against the top surface. A traction force (100 N) was applied to the anchor at six different angles (15°, 30°, 45°, 60°, 75° and 90°) against the top surface. Elastic analysis was performed, and the distribution of the von Mises equivalent stress inside the cube was calculated. The highest value of the equivalent stress at each traction angle was compared between the 45° and 90° anchor insertion settings.

RESULTS

Stress concentration was most evident around proximal anchor threads, particularly on the traction side. Interestingly, stress gradually declined with an increase in traction angle only for the 90° insertion setting. At 15° and 90° traction angles, the equivalent stress was lower for the 45° insertion setting than for the 90° insertion setting. In contrast, the 90° insertion setting exhibited lower equivalent stress than the 45° insertion setting at 30°, 45° and 60° traction angles.

CONCLUSIONS

Insertion of an anchor at 90° might reduce the stress concentration around the proximal anchor threads on the traction side and provide lower equivalent stress in the middle range of traction angles (30°-60°) than insertion at 45°. This could avoid early postoperative anchor failure.

X-treme CT analysis of cancellous bone at the rotator cuff insertion in human individuals with osteoporosis: superficial versus deep quality

PURPOSE

Rotator cuff (RC) repair-especially in the elderly population-is problematic since the patients suffer to a high extent from bone mineral density loss at the reattachment site. Therefore, the study was primarily driven by the question whether it is possible to reach more or qualitatively better cancellous bone and thus a more stable postoperative result if anchors with greater length are used for RC repair and/or the conventional anchors are screwed deeper into the bone. In anatomical terms, the question is raised whether cancellous bone is of better quality close to or far off the RC enthesis.

METHODS

Axial HRqCT scans (X-tremeCT, Scanco Medical) of 36 human cadaveric humeral heads (75 ± 11 years) were performed to determine the ratio of bone volume to total volume (BV/TV), trabecular thickness (Trab Th), number of trabecles (Trab N), trabecular separation (Trab Sp) as well as non-metric indices such as connectivity density (Conn Dens) and structure model index (SMI). Within the greater tuberosity (GT), 6 volumes of interest (VOI) (A1, B1, C1, A2, B2, C2), in the lesser tuberosity (LT) 2 VOIs (D1, D2) and one control VOI in the subchondral bone were set. The analyzed bone cylinder of each VOI was divided into a superficial and a deep portion.

RESULTS

The parameters BV/TV, Trab N, Trab Th and Conn Dens in all volumes of the GT and LT revealed higher values in the superficial portion reaching different levels of significance (p < 0.001/<0.05). The only parameter presenting a higher value in the deep portion was Trab Sp, but this was the case for all GT and LT regions. Interestingly, the difference between the superficial and deep portion reached significance for the non-metric parameter SMI in no volume of the GT/LT, although the higher values were found superficially.

CONCLUSIONS

Our data show that cancellous bone presents with decreasing bone quality when analyzing increasingly deeper portions of the bone cylinders of the GT and LT starting at the articular surface. This information seems to be crucial for shoulder surgeons, especially when treating elderly patients. Our results clearly prove that screwing in anchors to a deeper extent will not improve stability, since the deeper bone stock is of worse quality.

CD133: enhancement of bone healing by local transplantation of peripheral blood cells in a biologically delayed rat osteotomy model

Sufficient angiogenesis is crucial during tissue regeneration and therefore also pivotal in bone defect healing. Recently, peripheral blood derived progenitor cells have been identified to have in addition to their angiogenic potential also osteogenic characteristics, leading to the hypothesis that bone regeneration could be stimulated by local administration of these cells. The aim of this study was to evaluate the angiogenic potential of locally administered progenitor cells to improve bone defect healing. Cells were separated from the peripheral blood of donor animals using the markers CD34 and CD133. Results of the in vitro experiments confirmed high angiogenic potential in the CD133(+) cell group. CD34(+) and CD133(+) cells were tested in an in vivo rat femoral defect model of delayed healing for their positive effect on the healing outcome. An increased callus formation and higher bone mineral density of callus tissue was found after the CD133(+) cell treatment compared to the group treated with CD34(+) cells and the control group without cells. Histological findings confirmed an increase in vessel formation and mineralization at day 42 in the osteotomy gap after CD133(+) cell transplantation. The higher angiogenic potential of CD133(+) cells from the in vitro experients therefore correlates with the in vivo data. This study demonstrates the suitability of angiogenic precursors to further bone healing and gives an indication that peripheral blood is a promising source for progenitor cells circumventing the problems associated with bone marrow extraction.

Surgical treatment of three and four-part proximal humeral fractures

Three- and four-part fractures of the proximal humerus are usually treated surgically. Open reduction with internal fixation (ORIF) is the method of choice in younger patients. Anatomic reduction of the tuberosities is crucial to ensure that, in the event of poorly tolerated avascular necrosis of the humeral head, hemiarthroplasty can be performed under optimal conditions. Suboptimal outcomes may occur after ORIF, as less-than-perfect reduction and fixation is poorly tolerated at the shoulder. Preoperative computed tomography must be performed routinely to analyse fragment displacement and comminution, classify the fracture, assess humeral head vitality, and evaluate the mechanical properties of the underlying bone. Fracture reduction relies on principles that are shared by the various available techniques. Reduction of each fragment should be assessed separately. Reduction of the humeral head to the shaft should be performed before reduction of the tuberosities. The fixation technique should ensure stability of the anatomic reduction, with secure fixation of the tuberosities and a minimal risk of material migration into the joint. Here, we provide a detailed discussion of the various techniques, with their advantages and drawbacks, to help surgeons select the method that is most appropriate to each individual patient.

Anatomically reproducible assessment of volumetric bone mineral density--based on clinical computed tomography

Local distribution and quality of bone mineral density (BMD) in the proximal humerus are important for rotator cuff repair, internal fixations, and arthroplasty. The current study aimed to develop a volumetric BMD (vBMD) measurement technique that can specify the volumetric region of interest in an anatomically reproducible manner and ensures fair comparison of vBMD among intrasubjective or intersubjective measurements. Computed toed into three-dimensional (3D) polygon models. A standardized volumetric block was asmographic images of 10 intact shoulders (from six women and four men, age range 46-69 years) were reconstruct signed, and it included whole insertion areas of the supraspinatus and infraspinatus tendons on the greater tuberosity. For standardizing a bone block, a mathematical method for reproducible landmark assignment and reproducible local coordinate system was developed. After converting the polygonal standardized volumetric block into 3D tetrahedron finite element models, its vBMD was calculated. The repeatability and reproducibility standard deviations of the vBMD measurement method were found to be less than 2%. The current study developed a vBMD measurement technique that can specify the vROI in an anatomically reproducible manner and ensures fair comparison of BMD among intrasubjective or intersubjective measurements, with less than 2% reproducibility error.

Age-related changes in proximal humerus bone health in healthy, white males

The proximal humerus is a common site for osteoporotic fracture. The current study demonstrates the rate of age-related decline in proximal humerus bone health. The data suggest aging is associated with considerable loss of bone mass, structural deterioration and reduced bone strength at the proximal humerus.

INTRODUCTION

The proximal humerus is relatively under investigated despite being the fourth most common site for osteoporotic fracture.

METHODS

A cross-sectional study was performed to assess age-related changes in dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) properties of the proximal humerus in a cohort of 170 healthy, white males.

RESULTS

Regression models estimated considerable age-related loss of DXA measured bone quantity at the proximal humerus, with areal bone mineral density modeled to decline by 29% (95% confidence interval [CI], 17.5-35.0%) in the 50 years between ages 30 and 80 years (p < 0.001). pQCT measures indicated aging was associated with progressive periosteal and endosteal expansion, with the later occurring more rapidly as indicated by age-related declines in cortical bone mass, area and thickness (all p < 0.01). The net result of the density, mass and structural changes was a 26% (95% CI, 13.5-38.0%) decline in pQCT estimated proximal humerus bone strength in the 50 years between ages 30 and 80 years (p < 0.001).

CONCLUSION

Aging is associated with considerable declines in proximal humeral bone health which, when coupled with a traumatic event such as a fall, may contribute to osteoporotic fracture at this site.

Age and gender as determinants of the bone quality of the greater tuberosity: a HR-pQCT cadaver study

Background

Age-dependent trabecular changes of the humeral head might weaken the fixation of suture anchors used for rotator cuff (RC) repair. This might lead to suture anchor loosening and thus compromise the integrity of the repair. The aim of this study was to analyze whether the trabecular microstructure within the RC footprint is influenced by age, gender or handedness.

Methods

Axial HR-pQCT scans (Scanco Medical) of 64 freshly frozen cadaveric human humeral head specimens (age 72.3 ± 17.4 years) were analyzed to determine the bone volume-to-total volume ratio (BV/TV), trabecular thickness (Trab Th), trabecular number (Trab N) and connectivity density (Conn Dens). Within the RC footprint, 2 volumes of interest (VOI), posteromedial (PM) and anterolateral (AL) and one control VOI in the subarticular bone (SC) were set.

Results

The highest BV/TV was found in SC: 0.22 ± 0.06% vs. PM: 0.04 ± 0.05% vs. AL: 0.02 ± 0.04%; p < 0.05. Trab Th accounted for 0.26 ± 0.05 μm in SC, 0.23 ± 0.09 μm in AL and 0.21 ± 0.05 μm in PM. In parallel, Trab N and Conn Dens were found to be the highest in SC. Gender analysis yielded higher values for BV/TV, Trab Th, Trab N and Conn Dens for PM in males compared to females (p < 0.05). There were no significant findings when comparing both sides. We furthermore found a strong inverse correlation between age and BV/TV, which was more pronounced in the female specimens (r = −0.72, p < 0.00001).

Conclusions

The presented microarchitectural data allow for future subtle biomechanical testing comprising knowledge on age- and sex-related changes of the tuberosities of the humeral head. Furthermore, the insights on the trabecular structure of the humeral head of the elderly may lead to the development of new fixation materials in bone with inferior bone quality.

The Hounsfield value for cortical bone geometry in the proximal humerus--an in vitro study

INTRODUCTION

Fractures of the proximal humerus represent a major osteoporotic burden. Recent developments in CT imaging have emphasized the importance of cortical bone thickness distribution in the prevention and management of fragility fractures. We aimed to experimentally define the CT density of cortical bone in the proximal humerus for building cortical geometry maps.

METHODS

With ethical approval, we used ten fresh-frozen human proximal humeri. These were stripped of all soft tissue and high-resolution CT images were then taken. The humeral heads were then subsequently resected to allow access to the metaphyseal area. Using curettes, cancellous bone was removed down to hard cortical bone. Another set of CT images of the reamed specimen was then taken. Using CT imaging software and a CAD interface, we then compared cortical contours at different CT density thresholds to the reference inner cortical contour of our reamed specimens. Working with 3D model representations of these cortical maps, we were able to accurately make distance comparison analyses based on different CT thresholds.

RESULTS

We could compute a single closest value at 700 HU. No difference was found in the HU-based contours generated along the 500-900 HU pixels (p = 1.000). The contours were significantly different from those generated at 300, 400, 1,000, and 1,100 HU.

CONCLUSIONS

A Hounsfield range of 500-900 HU can accurately depict cortical bone geometry in the proximal humerus. Thresholding outside this range leads to statistically significant inaccuracies. Our results concur with a similar range reported in the literature for the proximal femur. Knowledge of regional variations in cortical bone thickness has direct implications for basic science studies on osteoporosis and its treatment, but is also important for the orthopedic surgeon since our decision for treatment options is often guided by local bone quality.

Reconstructive surgical treatment without bone grafting in nonunions of humeral surgical neck fractures

OBJECTIVE

To evaluate reconstruction surgery without bone grafting in humeral surgical neck nonunions using either a blade plate or the "Humerusblock" implant in small head fragments.

DESIGN

Retrospective cohort study, Evidence-Based Medicine Level IV.

SETTING

Paracelsus Medical University Salzburg, Department of Traumatology and Sports Injuries.

PATIENTS

Fifty-five patients (mean age, 66.2 years) with symptomatic nonunion after humeral surgical neck fractures were subjected to surgical reconstruction.

INTERVENTION

In 45 patients, open reduction and internal fixation using a blade plate was performed (Group 1). In 10 patients, the Humerusblock device was used (Group 2), because the head fragment of each of these patients was too small for plating. In no patients was bone grafting used.

MAIN OUTCOME MEASUREMENTS

Shoulder function, level of pain, and bone healing.

RESULTS

After a mean follow-up time of 74 months, the overall mean Constant score improved from 30.4% preoperatively to 83.2% postoperatively. The improvement was from 30.5% to 85.3% in Group 1 and from 32.2% to 75.4% in Group 2, which represented statistically significant improvements for both groups (P < 0.01). Radiologic bone healing was achieved in 51 patients (93%). The overall complication rate was high, 15%, and complications included plate loosening, avascular head necrosis, persistent nonunion, and infection.

CONCLUSIONS

Nonunion of humeral surgical neck fractures can be successfully treated by surgical reconstruction without bone grafting using either a blade plate or the Humerusblock for small head fragments. However, an increased complication rate is associated with this challenging posttraumatic pathology.

Total shoulder replacement for osteoarthritis in patients 80 years of age and older

This study was performed to review the safety and outcome of total shoulder replacements in patients who are ≥ 80 years of age. A total of 50 total shoulder replacements in 44 patients at a mean age of 82 years (80 to 89) were studied. Their health and shoulder status, the operation and post-operative course were analysed, including pain, movement, patient satisfaction, medical and surgical complications, radiographs, the need for revision surgery, and implant and patient survival. A total of 27 patients had an ASA classification of III or IV and medical abnormalities were common. Of the 13 shoulders with bony deficiency of the glenoid, nine required grafting. The duration of hospital stay was prolonged and blood transfusions were common. There were no peri-operative deaths. The mean follow-up was for 5.5 years (2 to 12). Pain was significantly reduced (p < 0.001) and movement improved in active elevation and both external and internal rotation (p < 0.001). Using the Neer scale for assessing outcome, 40 (80%) shoulders had an excellent or satisfactory result. There were medical or surgical complications in 17 cases. Four shoulders developed radiological evidence of loosened glenoid components, and three of these had a poor outcome. Three other shoulders required revision, two for instability. By the time of this review 39 of the patients had died from unrelated causes at a mean of 7.5 years (0.8 to 16.4) after surgery.

Total shoulder replacement is a relatively effective treatment in this elderly group of patients. However, there is a requirement for more intense patient care in the peri-operative period, and non-fatal medical or surgical complications are common. Most of these elderly patients will have a comfortable functional shoulder for the rest of their lives.

Assessment of bone quality within the tuberosities of the osteoporotic humeral head: relevance for anchor positioning in rotator cuff repair

BACKGROUND

Tears of the rotator cuff are highly prevalent in patients older than 60 years, thereby presenting a population also suffering from osteopenia or osteoporosis. Suture fixation in the bone depends on the holding strength of the anchoring technique, whether a bone tunnel or suture anchor is selected. Because of osteopenic or osteoporotic bone changes, suture anchors in the older patient might pull out, resulting in failure of repair.

HYPOTHESIS

The aim of our study was to analyze the bone quality within the tuberosities of the osteoporotic humeral head using high-resolution quantitative computed tomography (HR-pQCT).

STUDY DESIGN

Descriptive laboratory study.

METHODS

Thirty-six human cadaveric shoulders were analyzed using HR-pQCT. The mean bone volume to total volume (BV/TV) as well as trabecular bone mineral densities (trabBMDs) of the greater tuberosity (GT) and the lesser tuberosity (LT) were determined. Within the GT, 6 volumes of interest (VOIs) within the LT, and 2 VOIs and 1 control volume within the subchondral area beyond the articular surface were set.

RESULTS

Comparing BV/TV of the medial and the lateral row, significantly higher values were found medially (P < .001). The highest BV/TV, 0.030% + or - 0.027%, was found in the posteromedial portion of the GT (P < .05). Regarding the analysis of the LT, no difference was found comparing the superior (BV/TV: 0.024% + or - 0.022%) and the inferior (BV/TV: 0.019% + or - 0.016%) portion. Analyzing trabBMD, equal proportions were found. An inverse correlation with a correlation coefficient of -0.68 was found regarding BV/TV of the posterior portion of the GT and age (P < .05).

CONCLUSION

Significant regional differences of trabecular microarchitecture were found in our HR-pQCT study. The volume of highest bone quality resulted for the posteromedial aspect of the GT. Moreover, a significant correlation of bone quality within the GT and age was found, while the bone quality within the LT seems to be independent from it.

CLINICAL RELEVANCE

The shape of the rotator cuff tear largely determines the bony site of tendon reattachment, although the surgeon has distinct options to modify anchor positioning. According to our results, placement of suture anchors in a medialized way at the border to the articular surface might guarantee a better structural bone stock.

Bone quality measured by the radiogrammetric parameter "cortical index" and reoperations after locking plate osteosynthesis in patients sustaining proximal humerus fractures

AIM

To analyse the radiogrammetric parameter "cortical index" (CI) and its predictive value for proximal humerus fractures. Furthermore, to investigate the reoperations and the cause of reoperations after locking plate osteosynthesis of displaced proximal humerus fractures.

PATIENTS AND METHODS

113 consecutive patients (73 women and 40 men) with a median age of 66 years (range 18-100 years) were included in this study. The median follow-up time in our database was 4.7 years (range 45-72 months). For a comparative matched-group analysis of the CI, patients with a fall on the shoulder without fracture were selected. Demographic data and all reoperations were recorded after median 58 months postoperatively. The CI was measured at the proximal humeral diaphysis.

RESULTS

The CI showed to be significant lower in the fracture group (mean 0.28) when compared to the matched group (mean 0.47, p < 0.01). 39% patients underwent a reoperation within 40 months postoperatively. 24% were reoperated within the first 12 months postoperatively, and 15% were reoperated after 12 months or later. The reoperation was independent of bone quality (p = 0.85).

CONCLUSIONS

The risk for reoperation is independent of the CI even though the CI may be a predictor for proximal humerus fracture. Younger patients should be aware that surgical treatment of proximal humerus fractures might be a two-stage surgery. Regular follow-up visits for older patients during the first postoperative year must be assured.