A review of the coracoclavicular joint: Description, etiology, and clinical significance.

The coracoclavicular joint (CCJ) is a synovial joint that forms between the conoid tubercle of the clavicle and the coracoid process of the scapula in approximately 2.5% of the population. The number of bilateral to unilateral cases is almost equal. The number of right-sided and left-sided cases is also almost equal. It is found in both males and females but most often in male adults. Very few cases have been identified in juveniles. Found in populations all over the world, the highest frequencies of CCJ are in Asia. The etiology is unknown but it is most likely caused by metaplastic change of the trapezoid and surrounding tissue due to compression and friction of the coracoacromial ligament between the clavicle and coracoid process. Typically asymptomatic, but if so, the most common complaint is anterior should pain exacerbated by extreme abduction. Successful treatment includes steroid injection and surgical excision.

To be or not to be heavier: The role of dermal bones in the buoyancy of the Late Triassic temnospondyl amphibian Metoposaurus krasiejowensis.

Stereospondyli are a clade of large aquatic temnospondyls known to have evolved a large dermal pectoral girdle. Among the Stereospondyli, metoposaurids in particular possess large interclavicles and clavicles relative to the rest of the postcranial skeleton. Because of the large size of these dermal bones, it was first proposed that they served as ballast during hydrostatic buoyancy control which assisted metoposaurids to live a bottom-dwelling mode of life. However, a large bone need not necessarily be heavy, for which determining the bone compactness becomes crucial for understanding any such adaptation in these dermal bones. Previous studies on the evolution of bone adaptations to aquatic lifestyles such as osteosclerosis, pachyostosis, osteoporotic-like pattern and pachyosteosclerosis have been observed in the long bones of secondarily aquatic amniotes. However, there are no known studies on the analysis of bone compactness in the dermal pectoral girdle of non-amniote taxa including Temnospondyli. This study looks at evidence of changes in bone mass adaptations in the dermal bones of the pectoral girdle of two stereospondyls occurring in the Late Triassic Krasiejόw locality (Southwestern Poland), namely: Metoposaurus krasiejowensis and Cyclotosaurus intermedius. However, because of lack of research on bone compactness of temnospondyls in general, there is no existent frame of reference to infer bone mass increase (BMI) in the M. krasiejowensis samples, and thus the bone compactness results of this taxon are compared with that of the samples of C. intermedius. Results of this study indicate that the interclavicles of M. krasiejowensis partially evolved BMI-like condition rendering these bones to be heavy enough to get selected as ballast during hydrostatic buoyancy control. Additionally, M. krasiejowensis shared its habitat with C. intermedius, however, the dermal pectoral girdle sample of the latter taxon does not display signs of BMI-like condition. Furthermore, the absence of variation in hydrostatic buoyancy control in the ontogenetic series of interclavicles of M. krasiejowensis could imply lack of ontogenetic niche shift along the water column.

Contribution of the use of clavicle bone density in age estimation.

Age estimation is an essential element in the field of forensics and is also of judicial interest in forensic medicine of the living. Despite all the methods, age estimation is often imprecise with many biases, especially in mature individuals. The main objective of our study is to assess the correlation between age and computed tomography bone mineral density of the medial end of the clavicle. A sample of 180 chest multi-slice computed tomography scans without contrast injection performed in living individuals, with suspected respiratory infection, aged 15 to 100 years was used. Bone density measurement was performed on the medial meta-epiphyseal region of the clavicles. A significant negative correlation was found between bone density and age of individuals (p-value < 0.05). The mean absolute error was calculated for men at 13.4 years and 13.1 years for women, which was associated with an absence of bias. Good precision of the estimate for both sexes was also calculated on a subgroup of individuals whose age was greater than 40 years, with average absolute errors of about 12 years, which was associated with an absence of relative error. In view of our preliminary results, the study of bone density of the medial end of the clavicle could be of interest in the estimation of age. Several studies will be necessary to evaluate the reproducibility of these results on independent bone samples and in the estimation of age in the living individual.

Estimating age-at-death in burnt adult human remains using the Falys-Prangle method.

OBJECTIVES: The Falys-Prangle-method assesses age-related morphological changes to the sternal clavicle end (SCE), enabling the observation of mature adults from the 5th decade onwards in unburnt human skeletal remains. The aim of this study is to investigate the applicability of the Falys-Prangle-method on burnt human remains. MATERIALS AND METHODS: Fifty-two SCE of 40 cremated individuals (out of 86) from the William M. Bass collection of the Forensic Anthropology Center (Knoxville, Tennessee) of known age-at-death and sex are available for assessment. Surface topography, porosity, and osteophyte formation are evaluated, after which the calculated composite score is associated with the corresponding age range as described by Falys and Prangle. The method is also applied on an archaeological case study from Oudenburg, Belgium, dating to the Roman period. RESULTS: The assessed age ranges strongly agree with the true age ranges (α = 0.828), suggesting the Falys-Prangle-method to be applicable on burnt human remains. The case study from Oudenburg yields markedly improved age-at-death estimates, significantly enhancing our understanding of the age distribution within this community. DISCUSSION: Information on age-at-death is key in the construction of biological profiles of past individuals. The mature adult is often invisible in the archaeological record since most macroscopic age estimation methods do not distinguish beyond 46+ years old. Our study stresses the usefulness of a large-scale application of the Falys-Prangle-method, which will increase the visibility of mature adults, especially in archaeological burnt human skeletal collections, where such information is, at present, extremely difficult to obtain.

Anatomy and Correlation of the Coracoid Process and Coracoclavicular Ligament Based on Three-Dimensional Computed Tomography Reconstruction and Magnetic Resonance Imaging.

BACKGROUND The anatomy of the coracoid process and coracoclavicular (CC) ligament have been described and the correlation between them has been assessed based on 3-dimensional computed tomography (CT) reconstruction and magnetic resonance imaging (MRI), which provide a guide for coracoclavicular ligament reconstruction. MATERIAL AND METHODS Data were collected from 300 patients who underwent both CT and MRI of the shoulder joint from January 2017 to January 2019 at the Jiang'an Hospital of Traditional Chinese Medicine. The coracoid process was observed and classified and parameters of the CC ligament were measured according to different corneal types. All of the statistics were collected and classified by 2 radiologists, and average values were determined.Measurements of segments were taken as follows: ab - In the coronal plane, the length of the CC ligament from the central point of the CC ligament at the clavicular attachment to the CC ligament at the center of the CC attachment); ac - The distance from the center point of the CC ligament at the supraclavicular attachment to the acromioclavicular joint; de - In the sagittal plane, the length of the CC ligament from the center of the clavicular attachment to the coracoid attachment point; fg - The maximum diameter of the CC ligament at the anterior and posterior margins of the clavicle attachment; hi - The largest diameter of the CC ligament at the anterior and posterior edge of the coracoid process attachment; dj - The distance of the coracoclavicular ligament from the center point of the coracoid process attachment to the coracoid process tip; kl - The distance in the supraclavicular plane from the coracoclavicular ligament to the subcoracoid process. RESULTS The analysis showed that there are 5 types of coracoid process: gourd (31%), short rod (20%), long rod (22.3%), wedge (10.3%), and water drop (6.3%). There were statistically significant differences between the lengths of the ac and hi segments in the among the wedge and gourd-type and the short rod and water drop-type coracoid processes. There were statistically significant differences between the lengths of the ab, de, and fg segments in the short rod, gourd, and long rod-type coracoid processes. There were statistically significant differences between the lengths of the ac, fg, hi, dj, and kl segments in the water drop, gourd, and long rod-type coracoid processes. CONCLUSIONS The present study indicated that measurement of the CC ligament and the different shapes of the coracoid process provide an anatomical basis for the diagnosis and treatment of shoulder diseases and the data can be used to improve the safety of CC ligament reconstruction.

Sagittal orientation of coracoclavicular ligament reconstruction affects the stability of surgical repair.

BACKGROUND: The variation in the anatomic relationship between the coracoid and the clavicle affects the biomechanical stability of coracoclavicular ligament reconstruction (CCLR). METHODS: Three-dimensional computed tomography reconstruction of 85 patients was analyzed. Anatomic landmarks were used to derive the coracoclavicular sagittal reconstruction angle (sRA). The lateral concave angle, which indicated the shape of the distal clavicle, and the offsets between the clavicle and coracoid were also measured. To investigate the biomechanical effects of the sRA on CCLR, 7 computed tomography scans with different sRAs were 3D printed. Two reconstructions, a single trans-coracoclavicular tunnel and a looped reconstruction technique, were performed sequentially. Models were cyclically loaded at 70 N in the anterior, posterior, and superior directions. RESULTS: The mean sRA was 68° ± 9.3° (range, 47°-85°). The superoinferior offset between the clavicle and the coracoid and the lateral concave angle positively correlated with the sRA (r = 0.359 and 0.837, respectively; P ≤ .001), whereas the anteroposterior offset had a negative correlation (r = -0.925; P < .001). The sRA had a negative correlation with the anterior displacement of the clavicle (rho = -0.96; P < .001) and a positive correlation with the posterior displacement for both surgical techniques (rho = 1.0; P < .001). CONCLUSION: The anatomic orientation of the native coracoclavicular ligaments is highly variable in the sagittal plane. Low sagittal angles can reduce anterior stability, whereas high sagittal angles can reduce posterior stability of CCLR.

Anatomy of clavicle in the Indian population and its applicability in pre-contoured plating.

BACKGROUND: Fractures of the clavicle are traditionally treated non-operatively, but with the increase of high-energy trauma, there has been an increase in the operative management of these fractures. Controversy exists on the type of fixation for middle third clavicle fractures. The anatomically pre-contoured plates are low-profile mechanically sound plates which do not cause much soft tissue irritation. METHODS: To characterise the clavicular morphology through computerised tomography and determine the applicability of pre-contoured plates for our population. RESULTS: In this study, the mean total length was 145.31 mm and the apex of superior clavicle bow was located 38.15 mm from the acromial end, thereby giving a zone of 107.16 mm for plating. In the 107.16 mm of platable zone, the zone of ideal fracture location was 43.16 mm. Superior anterior plates had a good fit in 89.3% of the CT subset, whereas superior plates had a good fit in only 71.6% of the population. CONCLUSION: Superior anterior pre-contoured clavicle plates have approximately 98% good to fair compatibility for clavicles in the South Indian population without any need for further intra-operative moulding.

The relationship of the acromion to the distal clavicle in normal and symptomatic degenerated acromioclavicular joints.

INTRODUCTION: Although degenerative osteoarthritis of the acromioclavicular joint is a common finding on technical investigations, not every patient experiences pain or function loss. The difference between symptomatic and asymptomatic patients is currently not elucidated. Therefore, we want to investigate the acromioclavicular relationship in normal, asymptomatic, and symptomatic degenerated ACJ. MATERIALS AND METHODS: 84 normal ACJ, 39 asymptomatic degenerated ACJ, and 30 symptomatic degenerated ACJ were 3D reconstructed. The morphological dimensions and the relationship of the acromion and distal clavicle were measured using computational software. The reproducibility of this technique was evaluated using inter- and intra-observer reliability. RESULTS: The mean anteroposterior and superoinferior distance of both the clavicle and acromion was significantly larger in asymptomatic and symptomatic degenerative ACJ compared to the normal ACJ (p < 0.001). In symptomatic osteoarthritic ACJ, both the anterior and posterior borders of the acromion were significantly more anterior to the borders of the clavicle than in the normal group and asymptomatic group (p < 0.001). Subsequent ROC curve analysis resulted in a sensitivity of 86.7% and a specificity of 88.6% for anterior subluxation of the ACJ. This technique showed an excellent inter- and intra-observer reliability. CONCLUSIONS: In patients with degenerative ACJ, both the distal clavicle and acromion are enlarged. In asymptomatic patients, the AC relationship is the same as in normal patients, in contrast, in patients with symptomatic degenerative ACJ, the acromion is subluxated anteriorly compared to the clavicle.

Prevalence of the sternalis muscle in a sample of routinely dissected human cadavers.

PURPOSE: Sternalis muscle is an uncommon muscle head attaching between the sternoclavicular joint superiorly and the costal cartilage near the xiphoid process. METHODS: In this study, 36 cadavers (18 male, 18 female) were obtained through the Anatomical Board of the State of Florida and complete, routine musculoskeletal dissection was performed while adhering to all relevant laws and practices. RESULTS: Two examples of the sternalis muscle belly (5%) were identified, one in a black male and one a white female. The sternalis muscles were bilateral in both cases and each was formed of a single muscle belly. The superior attachments were continuous with the sternal attachment of sternocleidomastoid, and the inferior attachments connected to the costal cartilages. Sternalis did not cross the midline and the T2-T5 anterior intercostal neurovasculature associated closely with the muscle belly. In the female, a well-formed unilateral chondrocoracoideus muscle was apparent with a branch from the medial pectoral nerve closely associated on the deep surface. No other abnormalities in the chest, axilla, or brachial plexus were noted on either cadaver, and the pectoralis major and minor muscles were normally formed and innervated in both cases. CONCLUSION: This study supports other evidence in the literature that indicates the sternalis muscle has an average prevalence in the population of approximately 5%, and it appears across race and sex. Education about this structure is important for radiologists, surgeons, and doctors of physical therapy that may be involved in treatment and post-surgical rehabilitation of this region.

Radiological study of the Asian coracoid process and clavicle: Implications for coracoclavicular ligament reconstruction.

PURPOSE: Iatrogenic coracoid and clavicle fracture is a known complication of drilling bone tunnels during anatomic coracoclavicular ligament reconstruction (ACCR). This study aims to measure the dimensions of coracoid process and clavicle in an Asian population to evaluate the suitability of drilling coracoid and clavicle tunnels for ACCR in Asians. METHODS: Width measurements of 196 coracoids and 189 clavicles were obtained after reviewing all computed tomography (CT) scans of the shoulder performed over a 6 years period. Coracoid measurements were made on the CT slice which showed the maximum cross sectional width of the coracoid base. Medial to lateral measurements of the coracoid width were taken on an axial view, 4 mm above the identified junction of the coracoid base and glenoid base. Antero-posterior clavicle width was measured through a point directly above the midpoint of the coracoid and perpendicular to the long axis of the clavicle. RESULTS: The overall mean coracoid width was 14.8 mm ± 2.54 mm (range 9.2-23.3 mm) and clavicle width was 17.1 mm ± 2.72 mm (range 11.1-25.3 mm). CONCLUSION: The Asian coracoid process is smaller than its Western equivalent. More research is required to validate this conclusion as no cadaveric studies with equivalent measurement techniques have been performed on Asians. Given the potentially narrower dimensions of the Asian coracoid process, extra precautions are required to minimize the risk of iatrogenic coracoid and clavicle fractures.

Histovariability in human clavicular cortical bone microstructure and its mechanical implications.

The human clavicle (i.e. collarbone) is an unusual long bone due to its signature S-shaped curve and variability in macrostructure observed between individuals. Because of the complex nature of how the upper limb moves, as well as due to its complex musculoskeletal arrangement, the biomechanics, in particular the mechanical loadings, of the clavicle are not fully understood. Given that bone remodeling can be influenced by bone stress, the histologic organization of Haversian bone offers a hypothesis of responses to force distributions experienced across a bone. Furthermore, circularly polarized light microscopy can be used to determine the orientation of collagen fibers, providing additional information on how bone matrix might organize to adapt to direction of external loads. We examined Haversian density and collagen fiber orientation, along with cross-sectional geometry, to test whether the clavicle midshaft shows unique adaptation to atypical load-bearing when compared with the sternal (medial) and acromial (lateral) shaft regions. Because fractures are most common at the midshaft, we predicted that the cortical bone structure would show both disparities in Haversian remodeling and nonrandomly oriented collagen fibers in the midshaft compared with the sternal and acromial regions. Human clavicles (n = 16) were sampled via thin-sections at the sternal, middle, and acromial ends of the shaft, and paired sample t-tests were employed to evaluate within-individual differences in microstructural or geometric properties. We found that Haversian remodeling is slightly but significantly reduced in the middle of the bone. Analysis of collagen fiber orientation indicated nonrandom fiber orientations that are overbuilt for tensile loads or torsion but are poorly optimized for compressive loads throughout the clavicle. Geometric properties of percent bone area, polar second moment of area, and shape (Imax /Imin ) confirmed the conclusions drawn by existing research on clavicle macrostructure. Our results highlight that mediolateral shape changes might be accompanied by slight changes in Haversian density, but bone matrix organization is predominantly adapted to resisting tensile strains or torsion throughout and may be a major factor in the risk of fracture when experiencing atypical compression.

Differentiating supraclavicular from gluteal adipose tissue based on simultaneous PDFF and T2 * mapping using a 20-echo gradient-echo acquisition.

BACKGROUND: Adipose tissue (AT) can be classified into white and brown/beige subtypes. Chemical shift encoding-based water-fat MRI-techniques allowing simultaneous mapping of proton density fat fraction (PDFF) and T2 * result in a lower PDFF and a shorter T2 * in brown compared with white AT. However, AT T2 * values vary widely in the literature and are primarily based on 6-echo data. Increasing the number of echoes in a multiecho gradient-echo acquisition is expected to increase the precision of AT T2 * mapping. PURPOSE: 1) To mitigate issues of current T2 *-measurement techniques through experimental design, and 2) to investigate gluteal and supraclavicular AT T2 * and PDFF and their relationship using a 20-echo gradient-echo acquisition. STUDY TYPE: Prospective. SUBJECTS: Twenty-one healthy subjects. FIELD STRENGTH/SEQUENCE ASSESSMENT: First, a ground truth signal evolution was simulated from a single-T2 * water-fat model. Second, a time-interleaved 20-echo gradient-echo sequence with monopolar gradients of neck and abdomen/pelvis at 3 T was performed in vivo to determine supraclavicular and gluteal PDFF and T2 *. Complex-based water-fat separation was performed for the first 6 echoes and the full 20 echoes. AT depots were segmented. STATISTICAL TESTS: Mann-Whitney test, Wilcoxon signed-rank test and simple linear regression analysis. RESULTS: Both PDFF and T2 * differed significantly between supraclavicular and gluteal AT with 6 and 20 echoes (PDFF: P < 0.0001 each, T2 *: P = 0.03 / P < 0.0001 for 6/20 echoes). 6-echo T2 * demonstrated higher standard deviations and broader ranges than 20-echo T2 *. Regression analyses revealed a strong relationship between PDFF and T2 * values per AT compartment (R2 = 0.63 supraclavicular, R2 = 0.86 gluteal, P < 0.0001 each). DATA CONCLUSION: The present findings suggest that an increase in the number of sampled echoes beyond 6 does not affect AT PDFF quantification, whereas AT T2 * is considerably affected. Thus, a 20-echo gradient-echo acquisition enables a multiparametric analysis of both AT PDFF and T2 * and may therefore improve MR-based differentiation between white and brown fat. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:424-434.

Structural effects of variation in the human clavicle.

OBJECTIVES: Purported evolutionary shifts in shoulder structure have been linked to changes in hominin behavior and adaptation. Researchers use clavicle morphology to infer these shifts. However, there is a lack of empirical data underlying such predictive relationships. This study investigates how clavicle morphology affects articulated shoulder girdle and upper thorax configuration in humans. MATERIALS AND METHODS: Landmarks and scalar measurements on the clavicle, scapula, and ribs 1-3 were collected from three-dimensional computed tomographic scans of living humans. Covariation between disarticulated and articulated morphology was assessed using partial least squares and regression analyses. RESULTS: We found support for hypotheses linking combined dimensions of the clavicle, ribs, and scapula to resting protraction. Individuals with relatively short clavicles tend to exhibit protracted and elevated resting positions of the scapula. It is more difficult to predict superoinferior configuration, which is only minimally affected by clavicle curvature. Instead, the superoinferior position of the scapula on the thorax is governed equally by clavicle orientation and rib declination. Shoulder breadth is determined primarily by clavicle length, but orientation has a comparable effect. Therefore, reliable reconstructions of shoulder breadth can be established using clavicle length, together with consideration of orientation. Relationships between clavicle and thorax morphology are weaker. DISCUSSION: Understanding the determinants of variation in human shoulder structure informs interpretation of skeletal remains. Our investigations describe how important aspects of shoulder structure can be inferred from disarticulated clavicles and we provide the attendant predictive equations. Future work on interspecific variation will improve skeletal reconstruction for more ancient hominins.

Why off-the-shelf clavicle plates rarely fit: anatomic analysis of the clavicle through statistical shape modeling.

BACKGROUND: The clavicle presents a large variability in its characterizing sigmoid shape. Prominent and nonproperly fitting fixation plates (FP) cause soft tissue irritation and lead to hardware removal. It is therefore key in FP design to account for shape variations. Statistical shape models (SSMs) have been built to analyze a cluster of complex shapes. The goal of this study was to describe the anatomic variation of the clavicle using SSMs. METHODS: Two different SSMs of the clavicle were created, and their modes of variation were described. One model contained 120 left male and female clavicles. The other model consisted of 76 left and corresponding right clavicles, 41 originating from men and 35 from women. RESULTS: The model of 120 left clavicles showed that 10 modes of variation are necessary to explain 95% of the variation. The most important modes of variation are the clavicle length, inferior-superior bow, and medial and lateral curvature. Statistically significant differences between male and female clavicles were seen in length, sigmoid shape, and medial curvature. Comparison in men between left and right revealed significant differences in length and medial curvature. For women, a statistically significant difference between left and right was only seen in the length. CONCLUSIONS: Although the operative treatment of displaced midshaft clavicular fractures has clear benefits, the variable anatomy of the clavicle often makes it challenging for the surgeon to make the plate fit adequately. Based on the identified variability in the clavicle's anatomy, it seems unlikely that a clavicle plating system can fit the entire population.

Bilateral supernumerary clavicular heads of sternocleidomastoid muscle in a Korean female cadaver.

Many anatomical variants on the sternocleidomastoid muscle have been reported. In this study, supernumerary clavicular heads of sternocleidomastoid muscle in a Korean female cadaver were bilaterally displayed. The observed supernumerary heads were classified as follows: one sterno-mastoid, one cleido-occipital and one cleido-mastoid on the right side, and one sterno-mastoid-occipital, four cleido-occipitals, and one cleido-mastoid on the left side. The sterno-mastoid and sterno-mastoid-occipital and the cleido-occipital made the superficial layer of the sternocleidomastoid muscle, while others made deep layer. We discussed clinical relevance and developmental basis of these muscular variations important for clinicians and anatomists.

The dominant nutrient foramen at the clavicular midshaft: an anatomical study.

BACKGROUND: The aim of the present study was to describe the prevalence and topography of the dominant nutrient foramen at the clavicle. METHODS: 317 macerated human clavicles (167 right and 150 left) were available for the study. After detecting the dominant nutrient foramen, the total distance from the sternal surface to the examined nutrient foramen was measured. A foramen index (FI) was used for further data processing. RESULTS: We detected a dominant foramen in 300/317 (94.64%) clavicles, which was located in the middle third in 287/300 (95.7%) clavicles. The average clavicular length was measured at 14.9 cm ± 1.0 cm (range 11.6-17.5 cm) with an average foraminal distance from the sternoclavicular joint surface of 7.9 cm ± 1.3 cm (range 0.9-12.6 cm) in total. The mean FI was 53.2% ± SD 7.4% (range 5.5-79.3%). CONCLUSION: The present study provides a topographic mapping of the foraminal area (46-60% of the total clavicular length). The findings help to assess clavicular fracture patterns, which pass through the foraminal area.

The influence of biological affinity and sex on morphometric parameters of the clavicle in a South African sample.

OBJECTIVES: The present study aims to investigate the influence of environmental and functional factors associated with biological affinity and musculature on sexual dimorphism of the clavicle, and to develop population-specific methods of sex estimation from the clavicle. METHODS: The maximum length of the clavicle (MAXL), the sagittal diameter of the clavicle (SAGD), and the vertical diameter of the clavicle (VERD) were measured. The left clavicles of 198 South African coloured individuals (108 males and 90 females) were examined. RESULTS: Overall, the results of this study indicate that the SAGD of the clavicle is more sexually dimorphic than the VERD in the South African coloured sample. When the black American, white American, and Greek discriminant functions were applied to the South African coloured metric data, females were more accurately classified than males overall. Population-specific discriminant functions were created for the South African coloured sample. The original accuracy showed that females (85.5%) were more accurately classified than males (78.1%). Overall, the multivariate discriminant function demonstrated a higher correct classification of South African coloureds than the univariate discriminant functions. The results also suggest that univariate discriminant function equations are more accurate for sex estimation than univariate sectioning points in the South African coloured sample. CONCLUSIONS: Overall, the results of the present study indicate that the clavicle is an accurate predictor of sex and its dimensions are population-specific. Therefore, discriminant functions of the clavicle should only be used for sex estimation in forensic anthropology with the populations from which they were derived. © 2018 Wiley Periodicals, Inc.

Quantitative Assessment of the Coracoacromial and the Coracoclavicular Ligaments With 3-Dimensional Mapping of the Coracoid Process Anatomy: A Cadaveric Study of Surgically Relevant Structures.

PURPOSE: To perform a quantitative anatomic evaluation of the (1) coracoid process, specifically the attachment sites of the conjoint tendon, the pectoralis minor, the coracoacromial ligament (CAL), and the coracoclavicular (CC) ligaments in relation to pertinent osseous and soft tissue landmarks; (2) CC ligaments' attachments on the clavicle; and (3) CAL attachment on the acromion in relation to surgically relevant anatomic landmarks to assist in planning of the Latarjet procedure, acromioclavicular (AC) joint reconstructions, and CAL resection distances avoiding iatrogenic injury to surrounding structures. METHODS: Ten nonpaired fresh-frozen human cadaveric shoulders (mean age 52 years, range 33-64 years) were included in this study. A 3-dimensional coordinate measuring device was used to quantify the location of pertinent bony landmarks and soft tissue attachment areas. The ligament and tendon attachment perimeters and center points on the coracoid, clavicle, and acromion were identified and subsequently dissected off the bone. Coordinates of points along the perimeters of attachment sites were used to calculate areas, whereas coordinates of center points were used to determine distances between surgically relevant attachment sites and pertinent bony landmarks. RESULTS: The CAL had a single consistent acromial attachment (mean area 77 mm [51.9, 102.2]) and then bifurcated into 2 bundles, anterior and posterior, that separately inserted on the lateral aspect of the coracoid. The footprint areas were 54.4 mm2 [31.7, 77.2] and 30.6 mm2 [23.4, 37.7] for the anterior and posterior CAL bundles, respectively. These anterior and posterior bundles attached 10.6 mm [8.4, 12.9] and 24.8 mm [12.3, 27.4] medial and proximal to the apex of the coracoid process, respectively. The minimum distance between the coracoid apex and the trapezoid ligament was 25.1 mm [22.1, 28.1] and was noted to be different in males (28.1 mm [25.1; 31.2]) and females (22.0 mm [18.2, 25.9]). The most lateral insertion of the CC ligaments on the clavicle the AC joint was 15.7 mm [13.1, 18.3]. The distance between the most medial to the most lateral point of the CC ligaments on the clavicle was 25.6 mm [22.3, 28.9], which accounted for 18.2% [15.8, 20.6] of the clavicle length. CONCLUSIONS: In contrast to previous findings, 2 different coracoid attachments (anterior and posterior bundles) of the CAL were consistently identified in all specimens. Moreover, a coracoid osteotomy for a bone graft for the Latarjet procedure should be performed at less than 28.1/22 mm from the apex of the coracoid in male/female patients, respectively. The CC ligaments' attachments on the clavicle were located 15.7 mm from the AC joint, which should be considered for reconstruction. CLINICAL RELEVANCE: During the Latarjet technique, to maintain the integrity of the CC ligaments, precise knowledge of differences between male and female anatomy is necessary during a coracoid osteotomy. Furthermore, when reconstructing the AC joint, the distance from the lateral aspect of the clavicle and the size of the attachments areas should be considered to better replicate the native anatomy.

Distal clavicle fracture radiography and treatment: a pictorial essay.

Fractures of the distal clavicle represent 15-30% of all clavicle fractures. The local osseoligamentous anatomy and deforming forces result in increased risk of delayed union and nonunion than fractures in other parts of the clavicle. These factors also contribute to challenges in fracture repair. Understanding these injuries and their imaging features enhances care and ensures patients are directed to appropriate management. We review the anatomy of the distal clavicle and surrounding ligaments, options for radiographic evaluation, relevant classification systems, and current concepts in management. Illustrative examples of specialized views are provided. Pediatric acromioclavicular joint pseudosubluxation is also reviewed, with findings specific to that injury.

Quantifying shortening of the fractured clavicle assuming clavicular symmetry is unreliable.

BACKGROUND: One of the more commonly used methods of determining the amount of shortening of the fractured clavicle is by comparing the length of the fractured side to the length of contralateral unfractured clavicle. A pre-existing natural asymmetry can make quantification of shortening using this method unreliable. The goal of this study is to assess the side-to-side variation in clavicle length in 100 uninjured, skeletally mature adults. MATERIALS AND METHODS: To assess the side-to-side difference in clavicle length the length of both clavicles of 100 patients on thoracic computed tomography (CT) scans were measured. Patients without a history of pre-CT clavicular injury were included. The measurements were allocated into three groups based on the amount of asymmetry (< 5, ≥ 5-10 and > 10 mm). Dominant side and sex were analyzed to determine influence on the length of the clavicle. RESULTS: In 30 patients (30%), an asymmetry of 5 mm or more was found. 2% of the patients had a side-to-side difference of more than 10 mm. The absolute side-to-side length difference (LD) was 3.74 mm (95% CI 3.15-4.32; p < 0.001). A significant association between clavicle length and dominant side or sex was found (p < 0.001). CONCLUSION: These results show that by utilizing a treatment algorithm based upon clavicular symmetry has a potential for error and can lead over- or under-treatment of the fractured clavicle. A significant association between clavicle length and dominant side or sex was found (p < 0.001). LEVEL OF EVIDENCE: 2.