Anatomy of the clavicle and the intramedullary nailing of midclavicular fractures

Conformity of Three Pre-Contoured Clavicular Plates Compared Using Personalized 3D-Printed Models of Clavicles from Patients

The human clavicle's unique S-shaped, three-dimensional structure complicates fracture management. This study evaluated the anatomical conformity of pre-contoured anatomical plates using 3D-printed clavicle models. CT scans from 30 patients (15 males and 15 females) were used to create these models. Three brands of distal clavicle plate systems (Acumed, Synthes, and Arthrex) were tested for fit. Measurements included the distance from the distal end of the clavicle to the plate's lateral end, the gap between the clavicle and the plate, and the overhang distance. Results showed significant differences in clavicle length between sexes, with men having a mean length of 156.1 ± 7.6 mm and women 138.4 ± 4.3 mm, both with normal distribution (p > 0.05). The mean lateral distance was 7.9 ± 1.7 mm, and the mean medial gap was 3.6 ± 3.0 mm, showing no significant differences between products or sexes. The mean overhang distance was 5.8 ± 4.6 mm, with larger values in women for the Acumed (p = 0.037) and Arthrex (p = 0.000) plates. Overall, pre-contoured plates exhibited notable discrepancies, especially in shorter clavicles.

Normative Values for Sternoclavicular Joint and Clavicle Anatomy Based on MR Imaging: A Comprehensive Analysis of 1591 Healthy Participants

Background: The clavicle remains one of the most fractured bones in the human body, despite the fact that little is known about the MR imaging of it and the adjacent sternoclavicular joint. This study aims to establish standardized values for the diameters of the clavicle as well as the angles of the sternoclavicular joint using whole-body MRI scans of a large and healthy population and to examine further possible correlations between diameters and angles and influencing factors like BMI, weight, height, sex, and age. Methods: This study reviewed whole-body MRI scans from the Study of Health in Pomerania (SHIP), a German population-based cross-sectional study in Mecklenburg-Western Pomerania. Descriptive statistics, as well as median-based regression models, were used to evaluate the results. Results: We could establish reference values based on a shoulder-healthy population for each clavicle parameter. Substantial differences were found for sex. Small impacts were found for height, weight, and BMI. Less to no impact was found for age. Conclusions: This study provides valuable reference values for clavicle and sternoclavicular joint-related parameters and shows the effects of epidemiological features, laying the groundwork for future studies. Further research is mandatory to determine the clinical implications of these findings.

A fluoroscopic view for midshaft clavicular fracture reduction and internal fixation: posteroanterior 25° skyline projection

Background

Open reduction and internal fixation have been frequently applied for displaced midshaft clavicular fracture. Plate and screw fixation of clavicular fractures could provide rigid fixation and rotational control. Proper implant positioning in surgical fixation is critical to prevent iatrogenic complications. Fluoroscopy plays an important role in the intraoperative evaluation of implants. This study aimed to introduce a new fluoroscopic projection to evaluate the positioning of plates and screws.

Methods

Adult patients with a diagnosis of acute displaced midshaft clavicular fracture were included in this study. The slope angle of the midshaft clavicle was measured on sagittal reconstructions of preoperative computed tomography (CT) scans. The incidence of screw revision based on intraoperative standard posteroanterior (PA) and PA 25° cephalic skyline projections was compared. The interobserver agreement for the two projections was calculated.

Results

Twenty-nine patients with midshaft clavicular fractures were enrolled from January 2020 to June 2021. The PA 25° skyline projection could clearly display the tangential line of the plate and inferior border of the clavicle. The slope angle on the superior surface of the midshaft clavicle was 26.0 ± 5.8° (range: 18.5–38.3°). The incidence of screw revision using the PA projection (72.4%) was significantly different from that using the PA 25° skyline projection (34.5%) (P < 0.05). The concordance of the screw revision rate based on the standard PA and PA 25° skyline projections was strong, with kappa coefficients of 0.680 (95% CI: 0.394–0.968) and 0.776 (95% CI: 0.537–0.998).

Conclusion

The PA 25° skyline projection corresponds to the slope angle of the midshaft clavicle. It can provide more accurate information regarding the proper screw length and be applied as a routine method for intraoperative evaluation.

Does cerclage wiring interfere with fracture healing of osteosynthesis in comminuted midshaft clavicle fractures? A multicenter study

INTRODUCTION

Historically, cerclage wires were not used in the treatment of clavicle fractures because of their invasiveness. The purpose of this study was to evaluate the radiologic results and the incidence of complications following cerclage wire application and plate fixation in the treatment of comminuted mid-shaft clavicle fractures.

MATERIALS AND METHODS

A total of 116 patients with comminuted mid-shaft clavicle fractures who underwent open reduction and internal fixation were reviewed. We analyzed the postoperative length ratio and bone union period according to the fracture classification, patient age, the number of fragments and the number of applied wires. The thickness of the fracture site was compared with the normal contralateral clavicle shaft.

RESULTS

Bone union was confirmed in all enrolled patients at an average of 14.9±4.67 weeks. There are no significant differences in the length ratio or bone union period among the subgroups (including the fracture types, age, number of fragments and applied wires). The diameter at the occupied area was not significantly from that on the normal side (p=.505).

CONCLUSIONS

The application of a single cerclage or multiple cerclage wires around the fracture site did not hamper the clavicle shaft fracture healing. This result suggests that cerclage wires should not be avoided, but can be used as a viable treatment option for clavicle shaft fractures.

LEVEL OF EVIDENCE

IV.

Current concepts in the treatment of midshaft clavicle fractures in adults

Midshaft clavicle fractures are the most common fracture of the clavicle accounting for 80% of all clavicle fractures. Traditionally, midshaft clavicle fractures are treated with conservative treatment even when prominent displacement is observed; however, recent studies revealed that nonunion or malunion rate may be higher with conservative treatment. Moreover, recent studies have shown better functional results and patient satisfaction with surgical treatment. This review article provides a review of clavicle anatomy, describes the current clavicle fracture classification system, and outlines various treatment options including current surgical options for clavicle fracture in adults.

Morphometric Analysis of Clavicle and Its Medullary Canal: A Computed Tomographic Study

BACKGROUND

Intramedullary fixation is one of the common methods of treating clavicle fractures. Morphometric data of the clavicle and its medullary canal will help design a better device and surgical technique. Morphometric studies on clavicle are sparse; hence, this study.

METHODS

A 3-D reconstruction of 64 clavicles of 32 patients was done from computed tomography (CT) scan data of thorax obtained for the diagnostic workup of unrelated disease. The various dimensions of the clavicle and its medullary canal were measured. The narrowest part, point of change of direction of the medullary canal, curvatures of the clavicle, the position of the coracoid process, and the relation of these features to eight equally divided segments of clavicle were noted.

RESULTS

The average length of the clavicle was 142.5 mm. The average height and width of the narrowest part of the medullary canal were 2.4 mm and 2.5 mm, respectively, corresponding to segment 5 (S5) in more than half of the clavicles. The change of direction of the medullary canal and the medial edge of the coracoid process were corresponding to segment 6 (S6) in the majority of the clavicles.

CONCLUSION

This computed tomographic study provides morphometric data of the clavicle applicable to intramedullary fixation of clavicle fractures. In the studied population, the clavicles were shorter, more curved, and had medullary canal dimensions less than 2.5 mm at the narrowest part. This may pose difficulties in intramedullary fixation. The coracoid process was a reliable anatomical landmark.

The long-term efficacy of the GraftRope technique

BACKGROUND

Acromioclavicular joint separations continue to be a challenge for surgeons, and modern arthroscopically assisted techniques are becoming increasingly widespread. The aim of this study is to evaluate if the use of a biological support in association with a nonresorbable subcoracoid fixation can improve long-term stability in acromioclavicular joint dislocation surgically treated. We assessed clinical and radiographic results, patients' return to daily activities and the risk of complications.

MATERIALS AND METHODS

Fourteen patients underwent subcoracoid fixation with the GraftRope system for chronic Rockwood type IV acromioclavicular joint dislocation. A total of 12 patients were evaluated clinically and radiologically with a minimum of 7 years of follow-up.

RESULTS

Good reduction was obtained in all patients. All patients returned to work and sports at the pretrauma level with high mean scores on clinical evaluation. Regarding complications, 3 patients developed acromioclavicular arthritis. Ossifications were a common finding on x-rays, but they did not worsen the clinical outcome.

CONCLUSIONS

The GraftRope surgical technique allows us to obtain an anatomical reduction of the acromio-clavicular joint, along with the restoration of the mechanical properties of the joint, owing to the use of a biological material with rigidity and load resistance features. Clinical results over the long term are encouraging. However, a 6-mm bone tunnel is too large since the average thickness of the coracoid process is only approximately 12 mm. This technique has some advantages over others: it avoids detachment of the deltoid, avoids the use of bulky metal implants with an important dissection of soft tissue, while it has all the advantages of an arthroscopic procedure.

Management of clavicle shaft fractures with intramedullary devices: a narrative review

INTRODUCTION

Displaced and shortened clavicle fractures are frequently treated surgically. Although extramedullary fixation using a plate and screws is most commonly used, intramedullary nailing has become increasingly popular over the last decade. Traditional intramedullary nailing is usually associated with a high risk of hardware migration as well as hardware irritation at its entry point. Newer devices, however, seem to mitigate these problems. The aim of this narrative review is to provide an overview of clavicle shaft fractures and treatment with intramedullary nails, in particular the newer, locked devices.

AREAS COVERED

In general, this review covers current literature related to clavicle shaft fractures with a specific focus on the treatment of displaced and shortened fractures with intramedullary nails.

EXPERT OPINION

Clavicle shaft fractures can be effectively treated with an intramedullary nail. The risk of hardware migration when employing the newer, improved designs appears to be minimal. The advantages of using intramedullary fixation include smaller incision sizes as well as the avoidance of routine procedures generally associated with the removal of prominent subcutaneous hardware as per extramedullary fixation.

Development and biomechanical evaluation of a new biodegradable intramedullary implant for osteosynthesis of midshaft fractures of small hollow bones

BACKGROUND

Up to date there is no intramedullary, biodegradable osteosynthesis commercially available to treat non-comminuted midshaft fractures of small hollow bones applying not only a stable osteosynthesis but an additional axial compression to the fracture site.

OBJECTIVE AND METHODS

Therefore we (1) designed different implant profiles and simulated the inner tension/volume using CAD. (2) Thereafter we manufactured a prototype with the best volume/tension-ratio using 70:30 poly-(L-lactide-co-D, L-lactide) (PLLA/PDLLA) and poly-ε-caprolactone (PCL) by injection moulding. Both materials are resorbable, licensed for medical use and show a slow degradation over at least one year. (3) The implants were tested in a universal testing machine (Zwick/RoellZ010) using a 3-point-bending-setup. (4) We compared the implants with different types of commercially available Ti6Al4V 6-hole 2, 3 mm-plates including interlocking systems (Leibinger Set, Stryker) (each group n= 6) using a 4-point-bending-test-setup with artificial metacarpal bones (Sawbones®).

RESULTS

The 3-point-bending-test-results showed that mean failure-force of PCL-tubes was 57.94 ± 4.28 N whereas the PLLA/PDLLA-tubes had an approximately four-fold higher value of 227.24 ± 1.87 N (p< 0.001). Additionally, the 4-point-bending-test-results showed that the maximum load of PLLA/PDLLA tubes (61.97 ± 3.58 N) was significantly higher than the strongest 6-hole metacarpal plate (22.81 ± 0.76 N) (p< 0.001).

CONCLUSION

The study showed that the new type of biodegradable, intramedullary tension-osteosynthesis made of PLLA/PDLLA is even more stable than common plate osteosynthesis in a small-hallow-bone-model. Further in vivo investigation should be performed to evaluate the surgical technique and long-term healing process of the bone and biodegradation process of the implant.

Variation of the clavicle's muscle insertion footprints - a cadaveric study

The muscle footprint anatomy of the clavicle is described in various anatomical textbooks but research on the footprint variation is rare. Our goal was to assess the variation and to create a probabilistic atlas of the muscle footprint anatomy. 14 right and left clavicles of anatomical specimens were dissected until only muscle fibers remained. 3D models with muscle footprints were made through CT scanning, laser scanning and photogrammetry. Then, for each side, the mean clavicle was calculated and non-rigidly registered to all other cadaveric bones. Muscle footprints were indicated on the mean left and right clavicle through the 1-to-1 mesh correspondence which is achieved by non-rigid registration. Lastly, 2 probabilistic atlases from the clavicle muscle footprints were generated. There was no statistical significant difference between the surface area (absolute and relative), of the originally dissected muscle footprints, of male and female, and left and right anatomical specimens. Visualization of all muscle footprints on the mean clavicle resulted in 72% (right) and 82% (left) coverage of the surface. The Muscle Insertion Footprint of each specimen covered on average 36.9% of the average right and 37.0% of the average left clavicle. The difference between surface coverage by all MIF and the mean surface coverage, shows that the MIF location varies strongly. From the probabilistic atlas we can conclude that no universal clavicle exists. Therefore, patient-specific clavicle fracture fixation plates should be considered to minimally interfere with the MIF. Therefore, patient-specific clavicle fracture fixation plates which minimally interfere with the footprints should be considered.

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.

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.

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.

Anatomical study of the position and orientation of the coracoclavicular ligaments: Differences in bone tunnel position by gender

BACKGROUND

Reconstructing both coracoclavicular ligaments following acromioclavicular dislocation has recently been reported to restore the function of the acromioclavicular joint better than traditional procedures. Knowing the appropriate position and orientation of the bone tunnels and the potential risks of neurovascular injuries leads to safe reconstruction. We aimed to answer the following questions: what is the difference in the accurate clavicular bone tunnel positions (BTPs) during coracoclavicular ligament reconstruction between sex, and what are the potential risks for neurovascular injuries?

HYPOTHESIS

The BTPs differ by sex at the site of coracoclavicular ligament reconstruction.

PATIENTS AND METHODS

We introduced two Kirschner wires into 25 cadaver shoulders (17 male, 8 female), one through the insertion center of the trapezoid ligament and one through the conoid ligament, and measured the distance from the respective Kirschner wire insertion points to the bony landmarks of the clavicle and the oblique angle of each Kirschner wire. The shortest distance from the insertion point of each Kirschner wire to the suprascapular nerve and artery was also measured.

RESULTS

While the distance from the acromioclavicular joint to the respective Kirschner wire insertion points tended to be longer in males, the ratio of these insertion points to total clavicle length was constant. Other measurements for respective Kirschner wire insertions to the bony landmarks and neurovascular structures were comparable, as were abduction and retroversion angles. The distance from the suprascapular nerve to the insertion point of the conoid ligament at the coracoid process was 13.8±4.0mm, while the distance from the suprascapular artery was 7.1±3.3mm.

DISCUSSION

Appropriate position and orientation of the bone tunnels, and the ratio of the BTPs to the total clavicular length, aid surgeons in performing the reconstruction. The conoid ligament insertion on the coracoid was just proximal to the suprascapular artery, so surgeons should be careful with conoid insertion.

LEVEL OF EVIDENCE

V, cadaver study.

Morphometry of the human clavicle and intramedullary canal: A 3D, geometry-based quantification

Midshaft clavicle fractures are a very common occurrence. The current treatment of choice involves internal fixation with superior or anterior clavicle plating, however their clinical success and particularly patient satisfaction are decreasing. The implementation of intramedullary devices is on the rise, but data describing the intramedullary canal parameters are lacking. The aim of this study is to quantify the geometry of the clavicle and its intramedullary canal, and to evaluate the effect of gender and anatomical side. This study used three-dimensional image-based models with novel and automated methods of standardization, normalization, and bone cross-section evaluation. The data obtained in this study present intramedullary canal, and clavicle diameter and center deviation parameterized as a function of clavicle length as well as its radius of curvature and true length. Results showed that both right-sided and female clavicles were shorter and thicker, but only females showed a statistically significant difference in size compared to males (p < 0.0001). The smallest clavicle and intramedullary canal diameters were seen at different clavicle lengths (45% and 52%), suggesting that the narrowest region of intramedullary canal cannot be appreciated based on external visualization of the clavicle alone. The narrowing of the intramedullary canal is of special interest because this is a potential limiting region for surgical planning and intramedullary device design. Furthermore, the location and value of maximum lateral curvature displacement is different in the intramedullary canal, implying there exists an eccentricity of the intramedullary canal center with respect to the clavicle center. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2191-2202, 2017.

Midshaft clavicle fractures treatment: threaded Kirschner wire versus conservative approach

Clavicle fractures are common, accounting for 2.6 to 10% of all fractures. Treatment of these fractures is usually non-surgical. Recent evidence, however, reveals that the final result of non-surgically midshaft clavicular fractures, particularly those with quite large displacements or shortening, is not like that which was previously thought. This study evaluated retrospectively all patients presented with a clavicle fracture at Emergency Department of our Institution, between January 2006 and December 2011. Fractures were classified according to Allman’s radiographic classification system, modified by Nordqvist and Petersson. Patients were distinguished into two groups: one that underwent conservative treatment with a “figure-of-8” orthosis and one that underwent surgery with reduction in fracture and fixation with intramedullary threaded Kirschner wire. Pin removal was performed after 4 weeks of rest in Gilchrist bandage, after clinical and radiographic evaluation demonstrating the bone healing. The QuickDASH score and the Constant Murley Shoulder Score were used to evaluate the clinical outcomes. The radiographic outcome was evaluated at 1 and 6 months of follow-up. Database review provided a final cohort of 58 patients, with similar demographic features. There was no significant difference in qDASH and CS between the two groups. The results of qDASH and CS evaluated in function of the radiographic outcome show a statistically significant correlation between the worst qDASH and CS results and the grade of malunion in both groups. In particular, we have found unsatisfactory results when final shortening of the clavicle was 20 mm or more. On radiographic evaluation, surgical treatment demonstrated a greater efficacy in reducing initial shortening of the fractured bone; this is in opposition to conservative treatment that results very often in malunion, shortening, anatomic alterations and loss of functionality. The use of intramedullary threaded Kirschner wire for fixation of midshaft clavicle fractures is a safe procedure and is recommended in case of shortening greater than 2 cm in high-function-demand patients.

Morphometric Analysis of the Clavicles in Chinese Population

The clavicle has a complex geometry that makes plate fixation technically difficult. The current study aims to measure the anatomical parameters of Chinese clavicles as reference for plate design. One hundred clavicles were analyzed. The clavicle bone model was reconstructed by using computed tomography images. The length, diameters, and curvatures of the clavicle were then measured. The female clavicle was shorter, more slender, and less curved in lateral part than the male clavicle. There was a positive relationship between height and clavicle parameters except lateral curve and depth. The measurements of Chinese clavicles were generally smaller than Caucasians. The clavicle curves were correlated with the bone length; thus consideration of the curve variations may be necessary as designing size distribution of clavicle plate.

Congenital Anatomical Variant of the Clavicle

The aim of this study is to present a rare abnormality of the clavicle (Code: SGS01) that was discovered in an ossuary in the Church of San Gaetano (Sulmona, central Italy; XVII-XIX centuries CE). In the middle third, the clavicle had three areas with losses of substance in the form of oval-shaped foramina with maximum diameters of 1-2 cm that were located in the anterior and superior surfaces of the diaphysis. The margins of these foramina were well defined and rounded, and the surfaces of the canal walls were smooth. Additionally, there were no zones of bony activity or reactive changes around the foramina. This new congenital anomaly of the clavicle and blood vessels is consistent with a variant that might have originated during fetal growth in which the subclavian vein or artery remained included during the process of ossification of the clavicle. Anat Rec, 300:1401-1408, 2017. © 2017 Wiley Periodicals, Inc.

Quantitative anatomy of the growing clavicle in the human fetus: CT, digital image analysis, and statistical study

Purposes

Knowledge of dimensions of fetal long bones is useful in both the assessment of fetal growth and early detection of inherited defects. Measurements of the fetal clavicle may facilitate detection of numerous defects, e.g., cleidocranial dysplasia, Holt–Oram syndrome, Goltz syndrome, and Melnick–Needles syndrome.

Methods

Using the methods of CT, digital image analysis, and statistics, the size of the growing clavicle in 42 spontaneously aborted human fetuses (21 males and 21 females) at ages of 18–30 weeks was studied.

Results

Without any male–female and right–left significant differences, the best fit growth models for the growing clavicle with relation to age in weeks were as follows: y = −54.439 + 24.673 × ln(age) ± 0.237 (R² = 0.86) for length, y = −12.042 + 4.906 × ln(age) ± 0.362 (R² = 0.82) for width of acromial end, y = −4.210 + 2.028 × ln(age) ± 0.177 (R² = 0.77) for width of central part, y = −4.687 + 2.364 × ln(age) ± 0.242 (R² = 0.70) for width of sternal end, y = −51.078 + 4.174 × ln(age) ± 6.943 (R² = 0.82) for cross-sectional area, and y = −766.948 + 281.774 × ln(age) ± 19.610 (R² = 0.84) for volume.

Conclusions

With no sex and laterality differences, the clavicle grows logarithmically with respect to its length, width, and volume, and linearly with respect to its projection surface area. The obtained morphometric data of the growing clavicle are considered normative for their respective weeks of gestation and may be of relevance in the diagnosis of congenital defects.

Midshaft Clavicle Fractures: A Critical Review

The clavicle is the most commonly broken bone in the human body, accounting for up to 5% to 10% of all fractures seen in hospital emergency admissions. Fractures of the middle third, or midshaft, are the most common, accounting for up to 80% of all clavicle fractures. Traditional treatment of midshaft clavicle fractures is usually nonoperative management, using a sling or figure-of-eight bandage. The majority of adults treated nonoperatively for midshaft clavicle fractures will heal completely. However, newer studies have shown that malunion, pain, and deformity rates may be higher than previously reported with traditional management. Recent evidence demonstrates that operative treatment of midshaft clavicle fractures can result in better functional results and patient satisfaction than nonoperative treatment in patients meeting certain criteria. This article provides a review of relevant anatomy, classification systems, and injury mechanisms for midshaft clavicle fractures, as well as a comparison of various treatment options. [Orthopedics.2016; 39(5):e814-e821.].

Intramedullary Fixation of Clavicle Fractures: Anatomy, Indications, Advantages, and Disadvantages

Historically, management of displaced midshaft clavicle fractures has consisted of nonsurgical treatment. However, recent literature has supported surgical repair of displaced and shortened clavicle fractures. Several options exist for surgical fixation, including plate and intramedullary (IM) fixation. IM fixation has the potential advantages of a smaller incision and decreased dissection and soft-tissue exposure. For the last two decades, the use of Rockwood and Hagie pins represented the most popular form of IM fixation, but concerns exist regarding stability and complications. The use of alternative IM implants, such as Kirschner wires, titanium elastic nails, and cannulated screws, also has been described in limited case series. However, concerns persist regarding the complications associated with the use of these implants, including implant failure, migration, skin complications, and construct stability. Second-generation IM implants have been developed to reduce the limitations of earlier IM devices. Although anatomic and clinical studies have supported IM fixation of midshaft clavicle fractures, further research is necessary to determine the optimal fixation method.

Computerized tomography based 3D modeling of the clavicle

Previous studies have suggested clavicular morphology is highly variable, particularly in the lateral retrocurved section. Current clavicle fracture plating systems require three dimensional intra-operative contouring to achieve adequate fit and necessitate variable soft tissue dissection placing fracture perfusion and muscular attachments at risk. The aim of this study was to search for a surgically relevant superficial shape pattern. This is a retrospective CT-based analysis of 174 non-pathological clavicles in 95 adults (45 females, 50 males). Using the principle of cylindrical parameterisation generated 3-D computer models, we identified an implant preferred pathway (IPP), defined as a continuous linear region where the least possible soft tissue disruption would be necessary for plate fixation. The IPP mean form was within 3.04 mm (SD ± 1.34) on all clavicles. Clavicle length, and not shape, was found to be the biggest variable (correlation between size and form co-ordinates r = 0.99, p < 0.05), accounting for 79% of overall variability. This length variation was mainly located in the medial antecurved section. Superior convexity and recurvatum were the main shape variables, however they only contributed 8% and 5% to the overall variation, respectively. Three IPP lengths were shown to match all clavicles when aligned at the acromial end first. In contrast to previous studies, we have shown that the IPP is fairly consistent with respect to the general shape with the exception of length variation which mainly affected the medial antecurved section. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1216-1223, 2016.

CLINICAL RELEVANCE

Future pre-contoured fracture fixation systems should provide variable length plates with a constant lateral section retrocurve and a variable medial antecurve.

Titanium Elastic Nail versus plate fixation of displaced midshaft clavicle fractures: A retrospective comparison study

This study has two purposes: (1) to compare the clinical results between the Titanium Elastic Nail (TEN) and plate fixation of the displaced midshaft clavicle fracture; and (2) to demonstrate the relationship between length shortening and functional outcome after TEN fixation, especially in the comminuted fracture pattern. A retrospective, case-controlled study was conducted and 55 patients were included in our study: 25 in the TEN fixation group (TEN group) and 30 in the plate fixation group (plate group). All patients were classified into four subgroups: simple fracture in the TEN group (ST; n = 13), simple fracture in the plate group (SP; n = 15), comminuted fracture in the TEN group (CT; n = 12), and comminuted fracture in the plate group (CP; n = 15). Wound size was significantly smaller in the TEN group (p < 0.001). The injured clavicular length after fracture healing was significantly shorter in the TEN group (p = 0.036). There was no significant difference in the mean Constant and DASH scores. Injured clavicle shortening was significantly larger in the CT subgroup (p = 0.018). However, there was no statistically significant difference in Constant score and DASH score while comparing the CT subgroup to other subgroups. Although TEN fixation may lead to a higher degree of length shortening after bony union especially in cases of comminuted fracture pattern, no statistically significant difference was observed in objective functional results as compared to other subgroups. Therefore, TEN can be used to fix a displaced midshaft clavicle fracture even in cases of comminuted fracture pattern, which overall is an effective and less surgically invasive procedure.

A finite element parametric study of clavicle fixation plates

A finite element simulation on a fracture fixated clavicle was performed to study the effects of different fracture fixation parameters on the callus region. Specifically, parameters such as plate material, thickness, plate/bone gap, screw length, and locking vs. non-locking screws were explored. Plate thickness and locking vs. non-locking screws were found to be influential to construct stiffness where plate/bone gap and number of screws were not as sensitive.

Titanium Elastic Nail (TEN) versus Reconstruction Plate Repair of Midshaft Clavicular Fractures: A Finite Element Study

BACKGROUND

The biomechanical characteristics of midshaft clavicular fractures treated with titanium elastic nail (TEN) is unclear. This study aimed to present a biomechanical finite element analysis of biomechanical characteristics involved in TEN fixation and reconstruction plate fixation for midshaft clavicular fractures.

METHODS

Finite element models of the intact clavicle and of midshaft clavicular fractures fixed with TEN and with a reconstruction plate were built. The distal clavicle displacement, peak stress, and stress distribution on the 3 finite element models were calculated under the axial compression and cantilever bending.

RESULTS

In both loading configurations, TEN generated the highest displacement of the distal clavicle, followed by the intact clavicle and the reconstruction plate. TEN showed higher peak bone and implant stresses, and is more likely to fail in both loading configurations compared with the reconstruction plate. TEN led to a stress distribution similar to that of the intact clavicle in both loading configurations, whereas the stress distribution with the reconstruction plate was nonphysiological in cantilever bending.

CONCLUSIONS

TEN is generally preferable for treating simple displaced fractures of the midshaft clavicle, because it showed a stress distribution similar to the intact clavicle. However, TEN provides less stability, and excessive exercise of and weight bearing on the ipsilateral shoulder should be avoided in the early postoperative period. Fixation with a reconstruction plate was more stable but showed obvious stress shielding. Therefore, for patients with a demand for early return to activity, reconstruction plate fixation may be preferred.

Development of structural and material clavicle response corridors under axial compression and three point bending loading for clavicle finite element model validation

Clavicle injuries were frequently observed in automotive side and frontal crashes. Finite element (FE) models have been developed to understand the injury mechanism, although no clavicle loading response corridors yet exist in the literature to ensure the model response biofidelity. Moreover, the typically developed structural level (e.g., force-deflection) response corridors were shown to be insufficient for verifying the injury prediction capacity of FE model, which usually is based on strain related injury criteria. Therefore, the purpose of this study is to develop both the structural (force vs deflection) and material level (strain vs force) clavicle response corridors for validating FE models for injury risk modeling. 20 Clavicles were loaded to failure under loading conditions representative of side and frontal crashes respectively, half of which in axial compression, and the other half in three point bending. Both structural and material response corridors were developed for each loading condition. FE model that can accurately predict structural response and strain level provides a more useful tool in injury risk modeling and prediction. The corridor development method in this study could also be extended to develop corridors for other components of the human body.

Complications and technical pitfalls of titanium elastic nail fixation for midclavicular fractures

Intramedullary titanium elastic nails have been reported to fix displaced midclavicular fractures with excellent functional outcomes and minor complications. This study reports and analyzes the complications and technical pitfalls associated with titanium elastic nail fixation of displaced midclavicular fractures and describes how to prevent these problems. The authors operated on 27 patients (17 men, 10 women; mean age, 45.8 years; range, 16.5-66.9 years) with marked displaced midclavicular fractures using intramedullary titanium elastic nail fixation. The mean Constant score and Disability of the Arm, Shoulder, and Hand score were 93.58 (range, 66.5-100) and 6.22 (range, 0-35), respectively. The mean length difference compared with the contralateral clavicle was a shortening of 0.3 cm (range, -1.5 to 1 cm). Eight patients (30%) had different levels of difficulty at the medial entry point. Clavicular length shortening of more than 1 cm occurred in 5 patients (19%), and all of these patients experienced medial nail tip prominence/protrusion. One patient had 1-cm lengthening of the injured clavicle caused by distraction of the fracture site during titanium elastic nail insertion. Iatrogenic perforation of the posterolateral cortex occurred in 3 patients. Initial misplaced nail insertion occurred in 1 woman who underwent revision with the mini-open method. In 2 patients it was impossible to remove the full nail under general anesthesia. In conclusion, high patient satisfaction and functional outcomes were achieved after titanium elastic nail fixation of displaced midclavicular fractures. However, some complications and technical pitfalls must be considered before titanium elastic nails are used to fix displaced midclavicular fractures.

Biologic fixation through bridge plating for comminuted shaft fracture of the clavicle: technical aspects and prospective clinical experience with a minimum of 12-month follow-up

For comminuted shaft fracture of clavicle, the operative goal, aside from sound bone healing without complications of direct reduction, is maintenance of the original length in order to maintain the normal biomechanics of adjacent joint. Our bridge plating technique utilizing distraction through a lumbar spreader was expected to be effective for restoring clavicular length with soft tissue preservation. However, there are two disadvantages. First, there is more exposure to radiation compared to conventional plating; and second, it is difficult to control the rotational alignment. Despite these disadvantages, our technique has important benefits, in particular, the ability to preserve clavicular length without soft tissue injury around the fracture site.

Fractures of the clavicle: an overview

Fractures of the clavicle are a common injury and most often occur in younger individuals. For the most part, they have been historically treated conservatively with acceptable results. However, over recent years, more and more research is showing that operative treatment may decrease the rates of fracture complications and increase functional outcomes. This article first describes the classification of clavicle fractures and then reviews the literature over the past decades to form a conclusion regarding the appropriate management.

A thorough literature review was performed on assessment of fractures of the clavicle, their classification and the outcomes following conservative treatment. Further literature was gathered regarding the surgical treatment of these fractures, including the methods of fixation and the surgical approaches used. Both conservative and surgical treatments were then compared and contrasted.

The majority of recent data suggests that operative treatment may be more appropriate as it improves functional outcome and reduces the risk of complications such as non-union. This is particularly evident in mid shaft fractures, although more high grade evidence is needed to fully recommend this, especially regarding certain fractures of the medial and lateral clavicle.

Statistical shape analysis of clavicular cortical bone with applications to the development of mean and boundary shape models

During car collisions, the shoulder belt exposes the occupant's clavicle to large loading conditions which often leads to a bone fracture. To better understand the geometric variability of clavicular cortical bone which may influence its injury tolerance, twenty human clavicles were evaluated using statistical shape analysis. The interior and exterior clavicular cortical bone surfaces were reconstructed from CT-scan images. Registration between one selected template and the remaining 19 clavicle models was conducted to remove translation and rotation differences. The correspondences of landmarks between the models were then established using coordinates and surface normals. Three registration methods were compared: the LM-ICP method; the global method; and the SHREC method. The LM-ICP registration method showed better performance than the global and SHREC registration methods, in terms of compactness, generalization, and specificity. The first four principal components obtained by using the LM-ICP registration method account for 61% and 67% of the overall anatomical variation for the exterior and interior cortical bone shapes, respectively. The length was found to be the most significant variation mode of the human clavicle. The mean and two boundary shape models were created using the four most significant principal components to investigate the size and shape variation of clavicular cortical bone. In the future, boundary shape models could be used to develop probabilistic finite element models which may help to better understand the variability in biomechanical responses and injuries to the clavicle.

Anatomical study of the clavicle: endomedullary morphology

BACKGROUND

The treatment of clavicle fractures remains controversial. The objective of this study was to investigate the possibility of clavicular intramedullary fixation by nailing through an anatomic study combined with CT scan studies.

METHODS

For the anatomic study, 20 clavicles of donated bodies to science (10 men, 10 women, 10 right, 10 left) were used. We measured the length of the clavicle, lateral epiphysis diameter, mean diaphysis diameter, medial epiphysis diameter, lateral width, lateral radius of curvature, medial width and medial radius of curvature. Intramedullary cavity diameter (anteroposterior and superoinferior) and calibration were measured by CT scan study on 20 clavicles.

RESULTS

Average length was 152 mm for men and 140 mm for women. The anteroposterior curvature was most pronounced. The medullary canal had a gradually decreasing size from the distal portion to the middle segment, but never disappeared.

CONCLUSION

Evaluation of morphological data can clarify the specifications of an intramedullary nail: flexibility of the nail to match clavicle curvature and a locking system to ensure primary stability. Intramedullary fixation by nailing in displaced fractures of the middle portion of the clavicle is a minimally invasive surgical technique, with excellent functional and cosmetic results.

Clavicle morphometry revisited: a 3-dimensional study with relevance to operative fixation

BACKGROUND

The advocacy for operative fixation of midshaft clavicle fractures has prompted a reemergence of interest in clavicle anatomy. Three-dimensional (3D) anatomical studies provide more information than 2-dimensional studies, but are currently rare.

MATERIAL AND METHODS

Twenty-five skeletonized clavicles were digitized using a laser scanner. Three-dimensional computer software was used to analyze the data. Clavicles were divided into medial, middle, and lateral segments based on the medial and lateral apices of curvature and their lengths and midpoint cortical diameter measured. The angles of medial and lateral curvatures were measured in standardized axial and coronal planes. The medial and lateral curvatures were fitted with circles and the radii of curvature measured. Correlations between the intrinsic dimensions of the clavicle were assessed.

RESULTS

The mean length was 136.7 mm. The medial, middle, and lateral segments had mean lengths of 48, 56, and 32.7 mm, respectively. In the axial plane, the mean medial and lateral angles were 149.5° and 145.8°, respectively. In the coronal plane, the mean medial and lateral angles were 178.2° and 174.2°, respectively. The mean midpoint cortical diameter was 10.9 mm. The mean medial and lateral radii of curvature were 66.4 and 33.5 mm, respectively. The length and cortical diameter and length and medial radius of curvature were found to positively correlate, R(2) = .355 and .184, respectively.

CONCLUSION

Using standardized measurements, we were able to accurately characterize the dimensions of the clavicle. We found that the length of the clavicle correlates with the midpoint cortical diameter and with the radius of medial curvature.

Clavicle anatomy and the applicability of intramedullary midshaft fracture fixation

BACKGROUND

This study investigated the morphologic safety and applicability of intramedullary fixation of midshaft clavicle fractures by analyzing the pertinent clavicle anatomy using 3-dimensional computer simulation.

MATERIALS AND METHODS

Computed tomography was used to scan 22 skeletonized clavicles. Computer software was used to simulate middle-segment fracture fixation by fitting a cylindrical corridor within the clavicle in the area that intramedullary devices normally cross during surgery. The cylindrical corridor crossed the fracture line on both sides, and the number of cortical diameters that were bypassed was recorded. We assumed that 1 to 2 cortical diameters had to be bypassed to achieve adequate fixation. The medial and lateral exit points of the cylindrical corridor were measured and described in relation to the sternoclavicular and acromioclavicular ends respectively.

RESULTS

Simulation revealed that 15 of 22 clavicles could be bypassed by 2 cortical diameters on either side of the midline fracture, 6 clavicles could be bypassed by 1 cortical diameter medial to the fracture line, and 1 clavicle could not be bypassed by any cortical diameters medial to the fracture line. The medial exit point of the cylindrical corridor was anterior in 20 of 22 cases and an average of 44.2 mm lateral to the sternoclavicular end. The lateral exit point of the cylindrical corridor was posterosuperior in 16 of 22 cases and an average of 26.5 mm medial to the acromioclavicular end.

CONCLUSION

In most clavicles, straight intramedullary fixation appears to be a morphologically safe and effective method of fixation.

Treatment of clavicle fractures: current concepts review

Clavicle fractures are common in adults and children. Most commonly, these fractures occur within the middle third of the clavicle and exhibit some degree of displacement. Whereas many midshaft clavicle fractures can be treated nonsurgically, recent evidence suggests that more severe fracture types exhibit higher rates of symptomatic nonunion or malunion. Although the indications for surgical fixation of midshaft clavicle fractures remain controversial, they appear to be broadening. Most fractures of the medial or lateral end of the clavicle can be treated nonsurgically if fracture fragments remain stable. Surgical intervention may be required in cases of neurovascular compromise or significant fracture displacement. In children and adolescents, these injuries mostly consist of physeal separations, which have a large healing potential and can therefore be managed conservatively. Current concepts of clavicle fracture management are discussed including surgical indications, techniques, and results.

[Locking, multidimensional plate osteosynthesis of midshaft clavicle fracture]

BACKGROUND

The goal of this consecutive, retrospective clinical follow-up study was to analyse the quality of treatment with a multidimensional, anatomical locking plate osteosynthesis after comminuted clavicle shaft fracture (Robinson 2B).

PATIENTS AND METHODS

Of 38 operated patients, 35 were examined after locking plate osteosynthesis, with a median follow-up of 32 months (11-65). Four patients had suffered a 2B1 Robinson fracture and 31 patients a 2B2 Robinson fracture. The clinical and functional results were determined based on the standard clinical examination of the shoulder, the Constant and DASH scores, an analogue visual scale and a patient survey.

RESULTS

The clinical examination yielded a mean DASH score of 1.25, a mean Constant score of 98 and a mean VAS score on the visual analogue scale of 0.4 (with a range of 0-6). Neither nonunion nor implant failure was observed. We did, however, have one case of infection of the soft tissue.

CONCLUSION

The treatment of comminuted shaft fractures of the clavicle by means of a multidimensional locking plate is a safe treatment option that includes early functional postoperative care with free range of motion.

A parametric study of hard tissue injury prediction using finite elements: consideration of geometric complexity, subfailure material properties, CT-thresholding, and element characteristics

OBJECTIVE

The objectives of this study were to examine the axial response of the clavicle under quasistatic compressions replicating the body boundary conditions and to quantify the sensitivity of finite element-predicted fracture in the clavicle to several parameters.

METHODS

Clavicles were harvested from 14 donors (age range 14-56 years). Quasistatic axial compression tests were performed using a custom rig designed to replicate in situ boundary conditions. Prior to testing, high-resolution computed tomography (CT) scans were taken of each clavicle. From those images, finite element models were constructed. Factors varied parametrically included the density used to threshold cortical bone in the CT scans, the presence of trabecular bone, the mesh density, Young's modulus, the maximum stress, and the element type (shell vs. solid, triangular vs. quadrilateral surface elements).

RESULTS

The experiments revealed significant variability in the peak force (2.41 +/- 0.72 kN) and displacement to peak force (4.9 +/- 1.1 mm), with age (p < .05) and with some geometrical traits of the specimens. In the finite element models, the failure force and location were moderately dependent upon the Young's modulus. The fracture force was highly sensitive to the yield stress (80-110 MPa).

CONCLUSION

Neither fracture location nor force was strongly dependent on mesh density as long as the element size was less than 5 x 5 mm(2). Both the fracture location and force were strongly dependent upon the threshold density used to define the thickness of the cortical shell.

Malunion after midshaft clavicle fractures in adults

This is an overview of the current literature on malunion after midshaft clavicle fracture. Anatomy, trauma mechanism, classification, incidence, symptoms, prevention, and treatment options are all discussed. The conclusion is that clavicle malunion is a distinct clinical entity that can be treated successfully.

Minimally invasive fixation of displaced midclavicular fractures with titanium elastic nails

OBJECTIVES

Clavicular fractures account for 2.6% of all fractures, and more than 80% involve the middle third of the clavicle. Plate fixation has been the most common method of fixation reported but has been associated with complications such as infection, wound breakdown, nonunion, implant failures, poor cosmetic outcome, and local skin numbness. We report on a series of cases receiving minimally invasive insertion of titanium elastic nails (TEN) to fix the displaced midclavicular fractures.

DESIGN

Prospective, clinical study.

SETTING

Regional referral center.

PATIENTS/PARTICIPANTS

From November 2006 to October 2007, we operated on 23 patients (16 men) with displaced (no cortical contact between the proximal and distal fragments radiographically and/or greater than 2 cm of shortening) midclavicular fractures fixed with TEN. The mean age of the patients was 41.57 years.

INTERVENTION

All patients with displaced midclavicular fractures were treated with TEN. The nails were inserted from the medial entry point on the sternal end and passed through the fracture site under fluoroscopy monitoring.

MAIN OUTCOME MEASUREMENTS

Complications, clavicular shortening after TEN fixation, Constant shoulder score, and Disability of the Arm, Shoulder, and Hand score for functional outcome measurement.

RESULTS

Closed reduction was successful in 16 patients, and seven patients needed open reduction. There was no nonunion, infection, nail breakage, or refracture after nail removal in our series. The mean operative wound length was 2.2 cm, and mean clavicular length shortening was 0.32 cm. Iatrogenic perforation of the lateral cortex occurred in two patients, and nail misplacement occurred in one patient requiring revision. All patients followed up greater than 12 months. The mean Disability of the Arm, Shoulder, and Hand score was 6 (range, 0-35; standard deviation, 10.47) and mean Constant score was 96 (range, 78-100; standard deviation, 6.34).

CONCLUSIONS

Minimally invasive fixation with TEN is a safe method and can be performed with minor complications. This method of fixation of displaced midclaviclular fractures should result in a good cosmetic appearance and satisfactory stabilization of displaced midclavicular fractures without comminution.

Anatomic variation of the clavicle: A novel three-dimensional study

An understanding of the complex anatomy of the clavicle is helpful in the treatment of clavicular fractures. Using three-dimensional (3D) statistical shape analysis, the author presents a novel method to assess geometric morphology of the clavicle. Fifteen fresh frozen shoulder specimens were scanned using high-resolution computerized tomography (CT) but four were excluded from the study. A further 16 high-resolution CT scans of the clavicle were obtained by searching the hospital database. All 27 scans were reconstructed and subsequently imported into and analyzed using a specifically developed statistical software package. Using statistical shape analysis, geometric parameters were then measured. Both gender as well as side specific geometric morphology were observed. Clavicles in men were longer, wider, and thicker than in women. Right clavicles had a greater medial depth than left clavicles, especially in women. Clavicles in men had a greater lateral depth than in women. The sternal angle in women was larger than in men. Using 3D statistical shape analysis and applying it to the clavicle standardizes the study of its anatomy, rules out any variability, and calculates morphological parameters that are accurate, precise, and reproducible. This unique approach provides information that is useful not only to the clinician but also in the modification of current or design of future clavicle fixation devices. More importantly, from an anatomy standpoint, implementation of this novel approach in anatomical studies would eliminate intra- and interobserver variation and allow all studies to be standardized and thus more comparable.