Three-dimensional anthropometric analysis of the glenohumeral joint in a normal Japanese population

Comparison of short-term clinical outcomes and radiographic changes in Grammont reverse shoulder arthroplasty between the French and Japanese populations: A propensity score-matched analysis

BACKGROUND

Although Grammont-style reverse total shoulder arthroplasty (RSA) showed excellent clinical results in Europe, its utility for Asian populations remains unclear. This study aimed to compare the French and Japanese populations in terms of range of motion (ROM), functional outcomes, and scapular notching rates in patients who underwent standard Grammont-style RSA. We hypothesized that RSA for the Japanese population may not provide as good ROM and functional results at the final follow-up as that for the French population.

METHODS

A total of 25 Japanese patients undergoing RSA were propensity score matched to 25 French patients undergoing RSA. The patients were matched for four different covariates using a propensity score analysis. The minimum follow-up period was 2 years. We investigated differences between the populations with respect to body size and shoulder joint ROM and Constant score (CS) measured preoperatively and at the final follow-up. Scapular notching was examined using radiographs at the final follow-up.

RESULTS

The average height and weight of the French and Japanese patients were 164 cm and 70 kg and 152 cm and 56 kg, respectively. Anterior elevation (AE), external rotation (ER) at the side, internal rotation (IR), and CS total changed from 101° to 145°, 17° to 15°, 4.5 points to 5.5 points, and 36 points to 72 points, respectively, in the French population and from 63° to 119°, 8.5° to 13°, 4.6 points to 4 points, and 28 points to 58 points, respectively, in the Japanese population. AE improved in both the groups; ER and IR remained unchanged before and after surgery. The frequency of scapular notching (>grade 1) was higher in the Japanese population (56%) than in the French population (20%) (p = 0.019).

CONCLUSIONS

Grammont-style RSA improved AE and CS in both the populations, but AE and CS were significantly higher in the French population than in the Japanese population at the final follow-up. Scapular notching frequently occurs in the Japanese population.

Average Indian Glenoid Sizes Are Smaller than All Commercially Available Glenoid Components: A Systematic Review

Background

Despite the variability in glenoid sizes geographically, most of the currently available commercial glenoid component designs are based on the glenoid parameters of the Caucasian population which may not be suitable for the Indian population due to a mismatch between the prosthesis and native anatomy. The aim of the present study is to systematically review the literature to determine the average glenoid anthropometric parameters in the Indian population.

Methods

A comprehensive literature search was conducted using preferred reporting items for systematic reviews and meta-analyses guidelines in the PubMed, EMBASE, Google Scholar, and Cochrane Library databases from the date of inception to May 2021. Any observational study conducted on the Indian population measuring the glenoid diameters, glenoid index, version, inclination, or any other glenoid measurements were included in the review.

Results

A total of 38 studies were included in this review. The glenoid parameters were assessed on intact cadaveric scapulae in 33 studies, on 3DCT in three studies, and 2DCT in one study. The pooled average of glenoid dimensions are as the following- the superoinferior diameter or height was 34.65 mm, anteroposterior1 diameter or maximum width was 23.72 mm, anteroposterior2 diameter or maximum width of the upper part of the glenoid was 17.05 mm, the glenoid index was 67.88, and the glenoid version was 1.75-degree retroversion. Males were having a mean height of 3.65 mm and maximum width of 2.74 mm larger than the females. A subgroup analysis revealed no significant difference between different parts of India in glenoid parameters.

Conclusion

The glenoid dimensions in the Indian population are smaller compared to the average European and American populations. The average glenoid maximum width of the Indian population is 1.3 mm smaller than the minimum glenoid baseplate size available in reverse shoulder arthroplasty. Glenoid components specific to the Indian market need to be designed to reduce glenoid failure attributable to the above findings.

Level of evidence

III.

Study on geometry and morphology of proximal humerus in Northern Chinese population based on 3-D CT

BACKGROUND

This study investigated the characteristics of humeral geometric and morphological parameters in northern Chinese population by three-dimensional measurements, and compared whether there were differences in humeral morphology among populations from different geographical regions.

METHODS

Computed tomography scans of 80 humerus were obtained, reconstructed and measured. Differences in humeral morphological parameters between genders and sides were compared. Correlation analysis was used to explore possible correlations among the parameters. The differences in humeral geometric morphometric parameters between Western and East Asian populations were compared according to pool results of present and previous studies.

RESULTS

The average (and standard deviation) of humeral head radius curvature, arc angle, diameter, and thickness was 151.79 ± 6.69°, 23.36 ± 2.08 mm, 44.83 ± 3.92 mm and 17.55 ± 1.84 mm in coronal humeral head plane, and 152.05 ± 8.82°, 21.81 ± 1.88 mm, 41.77 ± 3.44 mm and 16.52 ± 1.92 mm in transversal humeral head plane. The average of the humeral head medial offset and posterior offset was 7.34 ± 2.47 mm and 0.08 ± 1.72 mm. Humeral head inclination angle, arc angle and radius curvature of humeral neck-shaft averaged 137.69 ± 4.92°, 34.7 ± 5.29° and 55.76 ± 13.43 mm. Superior, inferior, anterior, posterior concave angle of humeral anatomical neck averaged 150.41 ± 10.91°, 146.55 ± 10.12°, 146.43 ± 13.53° and 149.33 ± 14.07°. The average of height of the greater tuberosity, height of the lesser tuberosity, depth, concave angle and volume of the intertubercular groove was 14.19 ± 1.7 mm, 8.9 ± 1.54 mm, 0.92 ± 0.31 mm3, 31.28 ± 9.61 mm, 4.98 ± 1.19 mm and 89.35 ± 17.62°. The upper angle of the greater tuberosity averaged 161.04 ± 7.84°, the upper angle of the greater tuberosity was 165.94 ± 3.6°. Differences in parameters of proximal humerus between genders and sides were found. There was no correlation between parameters of proximal humerus and age. Correlations were found among humeral morphological parameters. East Asian populations differed in proximal humeral morphology from Western populations.

CONCLUSIONS

This study will provide references for diagnosing and classifying shoulder disease, designing prosthesis and instrument, enhancing surgical precision and guiding patient recovery.

Morphology of Humeral Head and Glenoid in Normal Shoulder of Indonesian Population

Purpose

Shoulder prostheses designed and used around the world may not fit an Asian shoulder. Normal shoulder morphology in Asian population had been reported, ie, Chinese, Indian, Japanese, and Thai populations, but no data from the Indonesian population. The aim of this study was to evaluate the three-dimensional (3D) morphology of the glenohumeral joint in the normal Indonesian population, identify its normal values, and compare them with those of other populations in the literature.

Patients and Methods

Images for analysis were computed tomography (CT) scans of 85 normal shoulders from 71 patients who had CT scans for another diagnosis. Morphometry of the humeral head and glenoid were measured using 3D reconstruction. Gender differences and correlations between age, height, and glenohumeral morphometry were evaluated. Indonesians' glenohumeral morphometry was compared with those of other populations in the literature.

Results

In the normal Indonesian population, the mean of humeral head inclination (HHI), height (HHH), diameter in sagittal plane (DS), diameter in frontal plane (DF), radius of curvature in sagittal plane (RS), and radius of curvature in frontal plane (RF) were 134.1°, 15.6mm, 39.3mm, 41.3mm, 20.4mm, and 21.4mm, respectively. The glenoid height (GH), upper width (GUW), lower width (GLW), inclination (GI), and version (GV) mean values were 34.2mm, 18.4mm, 24.5mm, 74.0mm, and 12.3mm, respectively. There was a significant difference in HHH, DS, DF, RS, RF, GH, GUW, GLW between males and females. Except for HHI and GI, glenohumeral morphometry was correlated with patient height. Age was not correlated with any glenohumeral morphometry.

Conclusion

In the Indonesian population, males had a larger humeral head and glenoid than females, and the size of the humeral head and glenoid was correlated to body height. Indonesians' humeral head and glenoid sizes were smaller than those of Western populations, but close to those of other Asian populations.

In Vivo Anatomical Research by 3D CT Reconstruction Determines Minimum Acromiohumeral, Coracohumeral, and Glenohumeral Distances in the Human Shoulder: Evaluation of Age and Sex Association in a Sample of the Chinese Population

Accurate measurement of the minimum distance between bony structures of the humeral head and the acromion or coracoid helps advance a better understanding of the shoulder anatomical features. Our goal was to precisely determine the minimum acromiohumeral distance (AHD), coracohumeral distance (CHD), and glenohumeral distance (GHD) in a sample of the Chinese population as an in vivo anatomical analysis. We retrospectively included 146 patients who underwent supine computed tomography (CT) examination of the shoulder joint. The minimum AHD, CHD, and GHD values were quantitatively measured using three-dimensional (3D) CT reconstruction techniques. The correlation between minimum AHD, CHD, and GHD value and age with different sexes was evaluated using Pearson Correlation Coefficient. The mean value of minimum AHD in males was greater than that in females (male 7.62 ± 0.98 mm versus female 7.27 ± 0.86 mm, p = 0.046). The CHD among different sexes differed significantly (male 10.75 ± 2.40 mm versus female 8.76 ± 1.38 mm, p < 0.001). However, we found no statistical differences in GHD with different sexes (male 2.00 ± 0.31 mm versus female 1.96 ± 0.36 mm, p > 0.05). In terms of age correlation, a negative curve correlation existed between age and AHD among the different sexes (male R2 = 0.124, p = 0.030, female R2 = 0.112, p = 0.005). A negative linear correlation was found in CHD among the different sexes (male R2 = 0.164, p < 0.001, female R2 = 0.122, p = 0.005). There were no differences between age and minimum GHD in both sexes. The 3D CT reconstruction model can accurately measure the minimum AHD, CHD, and GHD value in vivo and is worthy of further investigation for standard clinical anatomical assessment. Aging may correlate with AHD and CHD narrowing for both sexes.

The Y plane is a reliable CT-based reference for glenoid component positioning in shoulder arthroplasty

Purpose

To determine the reliability of anatomic references for mediolateral component positioning in shoulder arthroplasty.

Materials and methods

The computed tomography scans of 86 shoulders free of arthritic or anatomic deformities were studied. Two surgeons independently digitized a series of points, including the intersection of the 3 bone branches of the scapular spine (Y), the center of the glenoid surface (G), the most medial point of the scapula (MS), the cortical convergence (CC) of the anterior and posterior margins of the glenoid, the base of the coracoid (BC), the anterior (HA) and posterior (HP) margins of the subchondral bone.

Results

The mean mediolateral distances between G and Y, BC, CC were respectively − 19.6 mm, − 1.5 mm, and − 36.8 mm. The consistency of anatomic landmarks was greatest for Y (standard deviation (SD) =2.3 mm; interquartile range (IQR) =3 mm), compared to BC (SD = 4.6 mm; IQR = 7 mm), and CC (SD = 6.6 mm; IQR = 8 mm). The repeatability of anatomic landmarks was excellent for all measurements. The mean ratios (relative to humeral head size) of distances between G and Y, BC, CC were respectively − 0.45, − 0.04, and − 0.85. The consistency of ratios was greatest for Y (SD = 0.05; IQR = 0.06), compared to BC (SD = 0.11; IQR = 0.14), and CC (SD = 0.13; IQR = 0.17). The repeatability of ratios was excellent for Y and BC, while it was good for CC.

Conclusions

The Y-plane is a reliable reference for glenoid component positioning in shoulder arthroplasty, with a consistent distance from the center of the glenoid surface, and could therefore be suitable for preoperative planning.

Study design

Level III, comparative anatomic study.

Three-dimensional alignment of the upper extremity in the standing neutral position in healthy subjects

Background

Though alignment of the spine and lower extremities in the standing neutral position has been evaluated, a few studies evaluating the alignment of the upper extremities have also been made. This study assessed the normal alignment of the upper extremities in the standing neutral position and clarified the three-dimensional angular rotations of the upper extremity joints.

Methods

Computed tomography (CT) images of 158 upper extremities from 79 healthy volunteers were prospectively acquired in the standing neutral position using an upright CT scanner. Three-dimensional coordinate systems of the thorax, scapula, humerus, and forearm were designated, and three-dimensional angular rotations of the scapulothoracic, glenohumeral, and elbow joints were calculated.

Results

The median angle of the scapulothoracic joint was 9.2° (interquartile range [IQR], 5.2°–12.5°) of upward rotation, 29.0° (IQR, 24.9°–33.3°) of internal rotation, and 7.9° (IQR, 4.3°–11.8°) of anterior tilt. The median angle of the glenohumeral joint was 4.5° (IQR, 0.9°–7.8°) of abduction, 9.0° (IQR, 2.2°–19.0°) of internal rotation, and 0.3° (IQR, − 2.6°–3.1°) of extension. The median angle of the elbow joint was 9.8° (IQR, 6.9°–12.4°) of valgus, 90.2° (IQR, 79.6°–99.4°) of pronation, and 15.5° (IQR, 13.2°–18.1°) of flexion. Correlations in angular rotation values were found between the right and left upper extremities and between joints.

Conclusions

This study clarified the three-dimensional angular rotation of upper extremity joints in the standing neutral position using an upright CT scanner. Our results may provide important insights for the functional evaluation of upper extremity alignment.

Risk of penetration of the baseplate peg in reverse total shoulder arthroplasty for an Asian population

PURPOSE

Baseplate positioning may affect clinical outcome after reverse total shoulder arthroplasty (RTSA). The aim of this study was to evaluate the risk of penetration of the baseplate peg in RTSA.

METHODS

Forty-four patients with rotator cuff arthropathy or massive rotator cuff tears were included. Using their computed tomography data, ten insertion patterns of the baseplate pegs were simulated. First, in the axial plane, the baseplate was placed perpendicular to the Friedman axis (Friedman placement) and parallel to the glenoid surface (glenoid placement). Second, each of these placements were classified into the following groups: The baseplate peg was placed 2 mm anterior to the long axis of the glenoid (group A2), 1 mm anterior (group A1), on the long axis (group C0), 1 mm posterior (group P1), and 2 mm posterior (group P2). Cases in which the baseplate peg was within the scapular neck were defined as non-penetration, and the non-penetration rates among each group were evaluated and compared between sexes, and their relationship with patient height was evaluated.

RESULTS

In both the Friedman and glenoid placements, the non-penetration rate was significantly higher in groups A2 (68.2% and 70.5%) and A1 (65.9% and 65.9%) compared with groups P1 (18.2% and 29.5%) and P2 (9.1% and 13.6%; p < 0.001) and in males than in females (p < 0.05). Furthermore, the non-penetration rate tended to be higher as the patient's height increased.

CONCLUSIONS

It is recommended that the baseplate peg be placed anterior to the long axis of the glenoid.

Morphometric Evaluation of Detailed Asymmetry for the Proximal Humerus in Korean Population

Computer-assisted orthopedic surgery and patient-specific instruments are widely used in orthopedic fields that utilize contralateral side bone data as a template to restore the affected side bone. The essential precondition for these techniques is that the left and right bone features are similar. Although proximal humerus fracture accounts for 4% to 8% of all fractures, the bilateral asymmetry of the proximal humerus is not fully understood. The aim of this study is to investigate anthropometric differences of the bilateral proximal humerus. One hundred one pairs of Korean humerus CT data from 51 females and 50 males were selected for this research. To investigate bilateral shape differences, we divided the proximal humerus into three regions and the proximal humerus further into five sections in each region. The distance from the centroid to the cortical outline at every 10 degrees was measured in each section. Differences were detected in all regions of the left and right proximal humerus; however, males had a larger number of significant differences than females. Large bilateral differences were measured in the greater tubercle. Nevertheless, using contralateral data as a template for repairing an affected proximal humerus might be possible.

Factors related to large bone defects of bipolar lesions and a high number of instability episodes with anterior glenohumeral instability

Background

Significant bone defects are associated with poor clinical results after surgical stabilization in cases of glenohumeral instability. Although multiple factors are thought to adversely affect enlargement of bipolar bone loss and increased shoulder instability, these factors have not been sufficiently evaluated. The purpose of this study was to identify the factors related to greater bone defects and a higher number of instability episodes in patients with glenohumeral instability.

Methods

A total of 120 consecutive patients with symptomatic unilateral instability of the glenohumeral joint were retrospectively reviewed. Three-dimensional surface-rendered/registered models of bilateral glenoids and proximal humeri from computed tomography data were matched by software, and the volumes of bone defects identified in the glenoid and humeral head were assessed. After relationships between objective variables and explanatory variables were evaluated using bivariate analyses, factors related to large bone defects in the glenoid and humeral head and a high number of total instability episodes and self-irreducible dislocations greater than the respective 75th percentiles were evaluated using logistic regression analyses with significant variables on bivariate analyses.

Results

Larger humeral head defects (P < .001) and a higher number of total instability episodes (P = .032) were found to be factors related to large glenoid defects. On the other hand, male sex (P = .014), larger glenoid defects (P = .015), and larger number of self-irreducible dislocations (P = .027) were related to large humeral head bone defects. An increased number of total instability episodes was related to longer symptom duration (P = .001) and larger glenoid defects (P = .002), and an increased number of self-irreducible dislocations was related to larger humeral head defects (P = .007).

Conclusions

Whereas this study showed that bipolar lesions affect the amount of bone defects reciprocally, factors related to greater bone defects differed between the glenoid and the humeral head. Glenoid defects were related to the number of total instability episodes, whereas humeral head defects were related to the number of self-irreducible dislocations.

Three Dimensional Anthropometric Analysis of Glenoid Anatomy in Normal Indian Population

BACKGROUND

Shoulder unlike any other joint has a wide range of mobility and is important in day to day activities. Different ethnic groups vary in skeletal anatomy and anthropometry. Most of our knowledge on the shoulder-anatomy, surgical technique and prosthesis designs is based on western literature. There are few studies on the Indian population. Our aim is to study the anthropometry of glenoid based on 3D CT scan of the shoulder. Our objectives are to calculate glenoid height, width, version, inclination, analyse the data for differences between male and female, compare data with similar studies in India and other countries and study the impact on shoulder arthroplasty implant size.

MATERIALS AND METHODS

100 CT scans (male/female-50/50) of the Indian population are studied from our database. Glenoid measurements are calculated and analyzed.

RESULTS

The mean value of glenoid height is 32.9 ± 3.2 mm (27.6-41.7 mm), width 23.4 ± 2.62 mm (19.1-30.9 mm), version 0.07 ± 5.38° (- 11° to + 10.85°) and inclination 6.68 ± 5.49° (- 9.91° to + 20.75°). In our study glenoid is retroverted, superiorly inclined and height is more than width. The height and width are less than French and Americans but slightly more than the Japanese population.

CONCLUSION

There are significant differences in Indian glenoid measurements compared to other countries. Even the smallest size of shoulder arthroplasty glenoid component currently available in India is larger than the mean glenoid size of our study. As shoulder replacement surgeries are rising in India, we may have to bring changes in the implant design and surgical technique to suit our population.

Geometric analysis of the humeral head and glenoid in the Indian population and its clinical significance

BACKGROUND

Total anatomic and reverse shoulder prostheses are designed to match the dimensions of the native bony anatomy. Chinese and Japanese bony dimensions of the shoulder have been found to be different from that of the Caucasian population. We hypothesized that the geometric dimensions of the humeral head and glenoid in the Indian population would also be different from that of the Caucasian population.

METHOD

Fifty patients underwent computerized tomographic scans of their normal shoulders. We calculated the superoinferior (SI) diameter of the humeral head, anteroposterior diameter of the humeral head, radius of curvature of the humeral head, humeral head retroversion, humeral head thickness, inclination angle, critical shoulder angle, greater tuberosity angle, glenoid width, glenoid length, radius of curvature of the glenoid, glenoid inclination angle, and glenoid version.

RESULTS

The radius of curvature of the humeral head averaged 22.9 ± 1.7 mm, the articular surface thickness 17.1 ± 1.6 mm, and the SI diameter 42.3 ± 3 mm. The SI diameter strongly correlated with the thickness (r = 0.617, P = .001). The anteroposterior/SI articular surface diameter ratio averaged 0.9 ± 0.9, the articular surface thickness/radius of curvature ratio 0.7 ± 0.9, the inclination angle 133.8 ± 6.4, and the retroversion angle 33.5° ± 8.5°. The radius of curvature of the glenoid averaged 23.3 ± 3.4 mm, the glenoid width 24.0 ± 2 mm, the SI length 31.3 ± 2.2 mm, the glenoid inclination angle 78.7° ± 4.8°, and the glenoid retroversion 1.8° ± 3.8°.

DISCUSSION

Compared with the Western population, our cohort had a smaller humeral radius of curvature (P = .04), smaller articular surface diameter (P = .001), smaller inclination angle (P = .003), larger retroversion angle of the humeral head (P < .001), and smaller glenoid length and width (P < .0001). Most of the implant companies did not have smaller sized combinations of humeral heads with thickness to match our population. The glenoid width of females in our cohort was found to be smaller for the smallest size of the glenoid base plate.

CONCLUSION

Smaller sized options in humeral head diameter and thickness of the anatomic prosthesis and glenoid baseplate of the reverse shoulder prosthesis need to be made available to suit our population and avoid a mismatch.

Three-dimensional geometry of the normal shoulder: a software analysis

BACKGROUND

Three-dimensional (3D) geometry of the normal glenohumeral bone anatomy and relations is poorly documented. Our aims were (1) to determine the 3D geometry of the normal glenohumeral joint (GHJ) with reference to the scapular body plane and (2) to identify spatial correlations between the orientation and direction of the humeral head and the glenoid.

METHODS

Computed tomographies (CTs) of the normal, noninjured GHJ were collected from patients who had undergone CTs in the setting of (1) polytrauma, (2) traumatic head injury, (3) chronic acromioclavicular joint dislocations, and (4) unilateral trauma with a contralateral normal shoulder. We performed 3D segmentation and measurements with a fully automatic software (Glenosys; Imascap). Measurements were made in reference to the scapular body plane and its transverse axis. Geometric measurements included version, inclination, direction, orientation, best-fit sphere radius (BFSR), humeral subluxation, critical shoulder angle, reverse shoulder angle, glenoid area, and glenohumeral distance. Statistical correlations were sought between glenoid and humeral 3D measurements (Pearson correlation).

RESULTS

A total of 122 normal GHJs (64 men, 58 women, age: 52 ± 17 years) were studied. The glenoid BFSR was always larger than the humerus BFSR (constant factor of 1.5, standard deviation = 0.2). The mean glenoid version and inclination were -6° ± 4° and 7° ± 5°, respectively. Men and women were found to have significantly different values for inclination (6° vs. 9°, P = .02), but not for version. Humeral subluxation was 59% ± 7%, with a linear correlation with glenoid retroversion (r = -0.70, P < .001) regardless of age. There was a significant and linear correlation between glenoid and humeral orientation and direction (r = 0.72 and r = 0.70, P < .001).

CONCLUSION

The 3D geometry of the glenoid and humeral head present distinct limits in normal shoulders that can be set as references in daily practice: version and inclination are -6° and 7°, respectively, and humeral posterior subluxation is 59%; interindividual variations, regardless of the size, are relative to the scapular plane. There exists a strong correlation between the position of the humeral head and the glenoid orientation and direction.

Applied anatomical study on suprascapular nerve protection in reverse total shoulder arthroplasty

BACKGROUND

This study aimed to investigate the three-dimensional (3D) anatomical relationship between the suprascapular nerve and scapula, and the method of protecting the suprascapular nerve in reverse total shoulder arthroplasty (RTSA) METHODS: In the present study, 12 fresh adult cadaver shoulder specimens were dissected. X-ray and computed tomography (CT) were used to investigate the 3D scapular and suprascapular nerve images.

RESULTS

The results revealed that the best fitting baseplate diameter was 24.73 ± 1.56 mm. Furthermore, the baseplate diameter correlated with the glenoid cavity width. After the osteotomy, a simulated screw placement on the baseplate was performed. The dangerous area for the posterior screw placement was at the angle between the upper edge and transverse axis exceeding 38° and between the lower edge and transverse axis exceeding 76°. The distance between the nearest point of the nerve and osteotomy plane was 15.38 ± 2.02 mm, and the angle between the projection point of the nearest point and transverse axis was 27.33 ± 7.96°, which was the dangerous area for retractor placement. The suitable angle between the superior screw and longitudinal axis was 21.67 ± 13.27°, and the suitable superior screw length was 34.66 ± 2.41 mm.

CONCLUSION

In RTSA, the baseplate size correlates with the glenoid cavity width. The relationship between the screw and suprascapular nerve and retractor placement position should be carefully considered to avoid damaging the suprascapular nerve.

An interpopulation comparison of 3-dimensional morphometric measurements of the proximal humerus

Background

Precise anatomic reconstruction of the proximal humerus is essential to a favorable outcome of total shoulder arthroplasty. Because of the wide variation in the geometric features of the proximal humerus, prosthetic designs incorporating these disparities are being developed.

Methods

The aim of this study is to use data obtained from cadavers and computed tomographic scans to investigate the 3-dimensional morphometric parameters of the proximal humerus of South African and Swiss samples and make an interpopulation comparison. In addition, the study combines the interarticular variations between populations with the differences in sex and shoulder sides. With the aid of medical imaging techniques and engineering design tools, various geometric features were measured.

Results

The results obtained from these analyses revealed several differences in sex and shoulder sides. On average, the Swiss were larger in most of the measured parameters than the South Africans. The male shoulders of Swiss and South Africans were observed to significantly vary in 4 of the parameters measured. The South African male and female right shoulders varied considerably in one-fourth of the measured shoulder variables. Generally, for both populations, the left and right shoulders of the same individuals were not different in all the measured variables irrespective of sex.

Conclusion

The knowledge acquired in this study is expected to assist in the development of a population-specific shoulder prosthetic design and surgical planning procedures.

Anatomic limitations of biceps tenodesis using an interference screw for Asian people: a cadaveric study

Background

Biceps tenodesis using an interference screw has been commonly performed in clinical practice because of pathologic changes. Especially, the tenodesis distal to the bicipital groove, such as suprapectoral tenodesis (SPT) and subpectoral tenodesis (SBT), has been performed to avoid residual anterior shoulder pain. However, the techniques were developed based on research tested on Western population, and it is unknown whether they are applicable to Asian individuals, who have a smaller humerus than Western. The purpose of this study was to investigate the anatomic limitations of the biceps tenodesis using an interference screw for Asians.

Methods

We analyzed 22 fixed Japanese cadavers. We measured the length of the suprapectoral tenodesis zone (STZ), which is the area from the distal end of the lesser tuberosity to the proximal border of the insertion of the pectoralis major muscle tendon (PMMT) along the course of the biceps tendon, for the SPT. We also measured the bone tunnel depths (BTDs) for the SPT just distal to the lesser tuberosity along the course of the biceps tendon and, similarly, for the SBT just distal to the PMMT insertion. Finally, we analyzed the sexual differences and correlations of the measured values with the entire humeral length.

Results

In 9 shoulders (40.9%), the proximal border of the PMMT insertion was attached more proximally than the distal end of the lesser tuberosity, and the length of the STZ was negative. The mean BTDs in the SPT and SBT zones were 19.6 and 14.9 mm, respectively. In 11 shoulders (50%), the BTD in the SBT zone was shorter than 15 mm. The lengths of the STZ or BTDs in the SPT and SBT zones did not show statistical differences between sexes and were not correlated with the entire humeral length.

Conclusion

Asian patients would have anatomic limitations as follows for the biceps tenodesis regardless of their sex or body size. In anomalous PMMT cases, when the SPT was performed just proximal to the PMMT insertion, the bone tunnel entered into the bicipital groove. On the other hand, when the SPT was performed distal to the lesser tuberosity, a part of the PMMT insertion would be injured. Regarding the SBT, an interference screw with a length of ≥12 mm, which is commonly used in Western countries, is too long for Asians.

Three-dimensional alignment changes of the shoulder girdle between the supine and standing positions

Background

Although humans spend most of their day in a standing or sitting position, it is difficult to accurately evaluate the alignment of the shoulder girdle during daily activity, and its alignment changes between positions. The purpose of this study was to evaluate the 3-dimensional alignment of the shoulder girdle in the supine and standing positions by computed tomography (CT) and to assess the alignment changes of the shoulder girdle between these two positions.

Methods

CT scans of both shoulders of 100 healthy volunteers were prospectively taken in both supine and standing positions on the same day. The local 3-dimensional coordinate systems of the thorax, clavicle, and scapula were defined from the specific bony landmarks, and 3-dimensional angular rotations and positions of the clavicle and scapula were calculated. Differences in rotations and positions of the clavicle and scapula were evaluated between the supine and standing positions.

Results

Compared with the supine position, the clavicle showed significantly less elevation and greater retraction, and the scapula showed significantly less upward rotation, anterior tilting, and internal rotation in the standing position. Compared with the supine position, the clavicle center was located more inferiorly, posteriorly, and laterally, and the scapula center was located more inferiorly, posteriorly, and medially in the standing position.

Conclusions

The present study showed that angular rotations and positions of the clavicle and scapula change significantly with position due to the effect of gravity.

Assessment of the Glenoid Morphology Based on Demographic Data in the Turkish Population

Purpose

In this study, our aim was to evaluate the glenoid version, height, and width measurements based on gender, side, age, height, and hand dominance in the Turkish population using computed tomography (CT) images.

Methods

In our study, CT images of 140 patients (62 females and 78 males; mean age: 39.6 years) who had no shoulder complaints were evaluated retrospectively. Glenoid version (GV), AP diameter (width), and SI diameter (height) on both shoulders were measured on the CT images. Correlations between patient gender, side, age, height, and hand dominance and the GV and size were evaluated.

Results

The right shoulder had a mean GV of −0.93 ± 7.80 degrees and the left shoulder had a GV of −0.88 ± 6.63 degrees (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (

Conclusion

Hand dominance had an effect on the glenoid version, while patient gender, age, and height had an effect on the glenoid size. The glenoid width in the Turkish population was similar to that of the European and American populations, and the glenoid height was similar to that of the Asian population. Our GV values were similar to those of the Asian population and more anteverted compared to the Western population. We believe that our findings will be useful in preoperative planning and in the production of implants for our population.

Three-dimensional measurement of glenoid dimensions and orientations

BACKGROUND

Asians generally have smaller stature than Europeans and Americans, and currently available implants used in reverse shoulder arthroplasty might not fit smaller bony anatomies. However, few articles have reported glenoid geometry in the Asian population. The purpose of this study was to measure the dimensions and orientations of the glenoid from three-dimensional computed tomography reconstructions of elderly Japanese subjects.

METHODS

This study included 100 shoulders (50 males and 50 females with >50 years of age). The mean age was 67 ± 7 years for both sexes, and the mean height was 167 ± 7 cm for males and 154 ± 6 cm for females. Three-dimensional scapular models were created from computed tomographic images, and the glenoid height, glenoid width, glenoid version, glenoid inclination, vault depth, and vault width were measured.

RESULTS

The mean glenoid height and width were 38.6 and 29.4 mm for males and 33.1 and 24.4 mm for females, respectively. Both retroversion and superior inclination were approximately 3° in both sexes. The glenoid vault was deeper in the posterior region with the maximum depth of 26.1 and 23.6 mm in males and females. The vault width was narrower in the anterior region with the anterior width of 2.5 mm at 15 mm medial from the glenoid face in females.

CONCLUSION

Glenoids of Japanese females are small compared to currently available baseplates for reverse shoulder arthroplasty. These results may be helpful to aid design in smaller baseplates that better fit the anatomic geometry of the Asian glenoid.

Is CT scan a predictor of instability in recurrent dislocation shoulder?

PURPOSE

Glenoid bone defect and the defect on the posterior-superior surface of the humerus "Hill-Sachs lesion" are the commonly seen bony lesions in patients with recurrent dislocation shoulder. Computed tomography (CT) scan is considered as the best option in assessing the bony defects in the recurrent dislocation shoulder. The aim of this study was to assess the clinical and radiological co-relation in the patients with recurrent dislocation shoulder.

METHODS

Forty-four patients of recurrent dislocation shoulder who were evaluated between January 2015 and December 2017 at a tertiary care center, clinically and radiologically using CT scan and meeting the inclusion criteria, were included. The correlation between the clinical history of the number of dislocations and the bone loss using CT scan was evaluated. Two sided statistical tests were performed at a significance level of α = 0.05. The analysis was conducted using IBM SPSS STATISTICS (version 22.0).

RESULTS

All the patients were male with mean age of 25.95 (SD ± 4.2) years were evaluated. Twenty-four patients sustained injury in sporting activities while 20 patients sustained injury in training. There were an average of 4.68 (SD ± 3.1, range 2-15, median 3) episodes of dislocation. Forty-one patients had the glenoid bone loss while 40 had the Hill-Sachs lesions. The mean glenoid width defect was 10.80% (range 0-27%) while the mean Hill-Sachs defect was 14.27 mm (range 0-26.6 mm). The mean area of bone loss of the glenoid surface was 10.81% (range 0-22.4%). The lesions were on track in 34 patients and off track in 10 patients.

CONCLUSIONS

CT scan of the shoulder joint is an effective method for assessing the amount of bone loss. The number of dislocations are correlated significantly with off-track lesions and the amount of bone loss on the glenoid and Hill-Sachs lesion. The glenoid width bone loss of more than 9.80% or Hill-Sachs defect of more than 14.80 mm are the critical defects after which the frequency of dislocations increases.

Anthropometrical study of the human glenoid in a normal Spanish population

OBJECTIVE

To evaluate the size of the glenoid in a southern Spanish population, to compare it with previous results from other populations and determine the size of the implants that are marketed for shoulder arthroplasty.

MATERIAL AND METHODS

Between January 2015 and December 2017, an anthropometrical study of the human glenoid was performed using computed axial tomography scans (CT) of 154 patients over 30 years old. The glenoid dimensions were analysed 3-dimensionally using 2mm interval thicknesses, determining the average height and width of the glenoid. The upper point of the glenoid geometry was determined as the supraglenoid tubercle of the ovoid glenoid surface, where the long head of the biceps tendon is thought to originate. The lower point was then positioned at the furthest point from the upper point on the glenoid contour. Anterior and posterior points were determined such that the 3-dimensional anterior-posterior distance was maximized on the plane perpendicular to the upper-lower axis. Sex differences and correlations between sides and among the respective parameters in the glenohumeral dimensions were also evaluated.

RESULTS

The glenoid had an average height of 28.78mm and width of 20.27mm. The values were significantly different between the men and the women, being greater in the men. The glenoid size is well correlated with the patient's size. Direct correlations exist between the glenoid height and width and the glenoid size and the patient's height. The available metaglenoids currently on the market are no bigger than 25-24mm.

CONCLUSION

In comparison, the southern Spanish population have a glenoid size similar to the Caucasian population, but smaller than that of the American population. The data shown could be useful to improve the design of shoulder prostheses for the southern Spanish population.

Rationale for Small Glenoid Baseplate: Position of Central Cage within Glenoid Vault (Exactech® Equinoxe® Reverse System)

Background

Glenoid baseplate location is important to good clinical outcomes of reverse total shoulder arthroplasty (RTSA). The glenoid vault is the determining factor for glenoid baseplate location, but, to date, there are no reports on the effect of central cage location within the glenoid vault on RTSA outcomes when using the Exactech^® Equinoxe^® Reverse System. The purpose of this study was to determine the appropriate cage location in relation to the glenoid vault and monitor for vault and/or cortex penetration by the cage.

Methods

Data were retrospectively collected from the Samsung Medical Center (SMC) and Seoul National University Bundang Hospital (SNUBH). Patients who underwent RTSA between November 2016 and February 2018 were enrolled. Glenoid vault depth, central cage location within the vault were examined. Inferior glenoid rim–center distance, inferior glenoid rim–cage distance, and center–cage center distances were collected.

Results

Twenty-two patients were enrolled. Three SNUBH patients had inappropriate central cage fixation (33.3%) versus 4 SMC patients (30.8%). All cage exposures were superior and posterior to the glenoid vault. Mean center–cage distance was 5.0 mm in the SNUBH group and 5.21 mm in the SMC group. Center–prosthesis distance was significantly longer in the inappropriate fixation group than in the appropriate fixation group (p<0.024).

Conclusions

To ensure appropriate glenoid baseplate fixation within the glenoid vault, especially in a small glenoid, the surgeon should place the cage lower than usually targeted, and it should overhang the inferior glenoid rim.

A computed tomography analysis of three-dimensional glenoid orientation modified by glenoid torsion

Background

The longitudinal axis of the glenoid is not always parallel to the scapular body, and glenoid torsion could affect the values of glenoid orientation. The purpose of this study was to evaluate 3-dimensional glenoid version and inclination modified by glenoid torsion and to clarify the differences between the values of conventional and of modified glenoid orientations.

Methods

Computed tomography scans of 30 shoulders without shoulder pathology, 30 shoulders with primary osteoarthritis, and 30 shoulders with a massive rotator cuff tear or cuff tear arthropathy were retrospectively evaluated. After determining the glenoid axis and the scapular planes and calculating conventional glenoid version and inclination, modified glenoid version and inclination, and glenoid torsion, the values of conventional glenoid orientation and those of modified glenoid orientation were compared statistically.

Results

All shoulders showed anterior torsion of the glenoid with an average of 16° ± 5°. The values of modified glenoid retroversion were significantly smaller than those of conventional glenoid retroversion in all groups (P < .033), and the values of the modified glenoid inferior inclination were significantly larger than those of conventional glenoid inferior inclination in all groups (P < .001).

Conclusions

The present study showed that the glenoid twists with respect to the scapular body and that modification by glenoid torsion could affect the values of glenoid orientation. These results indicated that glenoid orientation with respect to the glenoid longitudinal axis will help surgeons determine proper placement of the glenoid component during shoulder arthroplasty.

Is global humeral head offset related to intramedullary canal width? A computer tomography morphometric study

Background

While most anatomic TSA stems allow some intra-operative adjustments, the default configuration assumes that head offset is directly proportional to stem diameter. Some authors reported that humeral head diameter is proportional to intra-medullary canal width and humeral head offset, but none investigated the direct relationship between head offset and endosteal measurements. The purpose of the study was to determine whether global humeral head offset is proportional to intramedullary canal width at the distal metaphysis and proximal diaphysis.

Methods

We analyzed 100 Computed Tomography shoulder scans of patients aged 59.1 ± 20.5 with no signs of gleno-humeral arthritis nor humeral dysplasia. The width of the intramedullary diaphyseal canal was determined at four transverse sections 65, 70, 100 and 105 mm below the head center. The inter-observer agreement was excellent for intramedullary canal width (ICC = 0.96), head diameter (ICC = 0.97) and global head offset (ICC = 0.85). Correlations were analysed using Pearson’s coefficients and multivariable regressions were performed to determine associations between head offset and five independent variables (gender, age, intramedullary canal width, head diameter).

Results

Global head offset was negatively correlated with head diameter (r = − 0.31, p = 0.002), but not correlated with intramedullary canal width (r = − 0.11, p = 0.282). Multivariable regression confirmed that global head offset was independently associated with head diameter (beta = − 0.15, p = 0.005), but not with intramedullary canal width (beta = 0.06, p = 0.431).

Conclusions

The present study revealed that humeral offset is not correlated with intramedullary canal width. Implant manufacturers and shoulder surgeons should be aware of the subtle morphologic features, to enhance humeral stem design and restore native anatomy.

A simple method to directly evaluate the lateral extension of the acromion: an anatomic study of 128 cadaveric scapulae

BACKGROUND

The lateral extension of the acromion from the glenohumeral joint is the critical variable that both the acromial index and critical shoulder angle reflect. The purpose of this study was to establish a simple and reproducible method to directly measure the lateral extension of the acromion that will be independent of patient demographic characteristics, scapular rotation, or other morphologic features of the shoulder.

METHODS

This study used 128 unpaired cadaveric scapulae with a mean age of 69.4 ± 11.1 years (66 right and 62 left scapulae, 65 female and 63 male cadaveric specimens). The lateral extension of the acromion was measured from the supraglenoid tubercle to the most lateral point of the acromion with a digital caliper placed perpendicular to the scapula long axis. This distance was called the "lateral offset of the acromion."

RESULTS

The lateral offset was 2.62 ± 0.72 cm in men and 2.69 ± 0.73 cm in women. The offset was 2.61 ± 0.66 cm in right and 2.70 ± 0.78 cm in left scapulae. The offset in the group aged 46-60 years was 2.85 ± 0.76 cm; in the group aged 61-75 years, it was 2.62 ± 0.76 cm; and in the group aged 76 years or older, it was 2.54 ± 0.60 cm. No significant difference was found between any of the groups.

CONCLUSIONS

This study established a simple method to directly measure the lateral extension of the acromion based on the longitudinal axis of the scapula, which eliminates bias that may exist in the acromial index and critical shoulder angle from the position of the scapula and glenoid inclination. The lateral offset was found to be independent of sex, side, or age, limiting bias in a potential future clinical application.

Evaluation of the Translation Distance of the Glenohumeral Joint and the Function of the Rotator Cuff on Its Translation: A Cadaveric Study

PURPOSE

To evaluate the distance and position of humeral head translation during glenohumeral motion and to investigate the function of the rotator cuff in glenohumeral translation.

METHODS

Using 9 cadavers, glenohumeral translation during passive pendulum motion was tracked by an optical motion capture system. Tension was applied to 5 compartments of the rotator cuff muscles, and 7 different conditions of rotator cuff dysfunction were sequentially simulated. Three-dimensional glenohumeral structure was reconstructed from the computed tomography images of the specimens, and the distance and position of glenohumeral translation were compared among the conditions.

RESULTS

The average radius of glenohumeral translation was 10.6 ± 4.3 mm when static loading was applied to all rotator cuff muscles. The radius increased significantly in the models without traction force on the supraspinatus and total subscapularis tendons (P = .030). The position of the translation center did not change in the mediolateral direction (P = .587) and in the anteroposterior direction (P = .138), but it moved significantly superiorly in the models without supraspinatus and infraspinatus loading (P = .011) and in those without supraspinatus, infraspinatus, and teres minor loading (P < .001).

CONCLUSIONS

The distance and position of humeral head translation during glenohumeral motion changed with rotator cuff deficiency. The present study indicated that the subscapularis plays an important role in maintaining the central position of the humeral head, and that the infraspinatus acts as a major depressor of the humeral head during shoulder motion.

CLINICAL RELEVANCE

The results of this study suggest that extension of a tear into the subscapularis should be avoided to maintain the centering function of the glenohumeral joint in cases with rotator cuff tear.

Spherical versus elliptical prosthetic humeral heads: a comparison of anatomic fit

BACKGROUND

The aim of this study was to quantify the influence of prosthetic humeral head shape, as well as the number of available prosthetic head sizes, on replicating the normal humeral head anatomy during shoulder reconstructive surgery.

METHODS

Computer modeling software was used to create virtual sets of both spherical and elliptical prosthetic heads, which were virtually implanted into 3-dimensional computed tomography scan-based models of 79 proximal humeri. Anatomic replication was considered successful if the measured parameters (diameters of the base of the head in the frontal and sagittal planes, radii of curvature in the frontal and sagittal planes, and humeral head height) were all reproduced within 3 mm. The Fisher exact test was used to compare the percentage of successful replications for both head types and to compare differences resulting from the use of sets with fewer or more available head sizes. Statistical significance was set at P ≤ .05.

RESULTS

Regardless of the number of available head sizes per set, it was possible to replicate the normal anatomy within 3 mm in a higher percentage of specimens using elliptical (96%-100%) as opposed to spherical (41%-78%) prosthetic heads (P ≤ .0013).

CONCLUSION

Compared with use of spherical prosthetic heads, use of elliptical heads resulted in improved replication of the normal humeral head shape. In light of the emerging evidence that use of anatomically shaped prosthetic humeral heads might lead to better shoulder function and possibly improved implant survivorship, the findings of this study may have important clinical and economic implications.

Impact of vertical and horizontal malrotation on measurements of anteroposterior radiographs of the scapula: need for standardized images in modern omometry

BACKGROUND

An increasing number of parameters measured on anteroposterior radiographs are used for the evaluation of the bony geometry of the scapula. Inhomogeneous acquisition of images is common because of the lack of standardization in radiographic positioning. Images with malrotation around the horizontal axis of the scapula are particularly frequent. We hypothesized that malrotated images would result in large variations in measured radiographic parameters and that image standardization using qualitative and semiquantitative "omometric" criteria would decrease these variations in measurements. "Omometry" is a newly introduced umbrella term that contains all standardized measurements on plain radiographs of the shoulder, analogous to the term "coxometry," which is widely used for the radiographic assessment of the osseous pelvis and hip.

METHODS

In this experimental, cadaveric radiographic study, 7 dry-bone human scapula cadaveric specimens from anonymous donors were used to obtain 210 radiographs. We incrementally rotated (steps of 3°) every scapula around its horizontal and vertical axis, with a total range of 42° per each axis. Then, we measured 5 radiographic parameters on every image and observed their change with malrotation. Furthermore, we introduced 4 omometric criteria defining an appropriate (presence of ≥3 criteria) radiographic image to improve standardization of scapular image acquisition.

RESULTS

Overall, measured values remained stable within a narrow range of ±9° of malrotation. Beyond this range, values of all parameters significantly deviated (>±2°) from the initial value. Measurements on appropriate images were significantly less prone to deviation. Within the appropriate images, those with 4 criteria showed a higher specificity than those with 3 criteria.

CONCLUSION

There is significant variation in values of measured radiographic parameters on anteroposterior radiographs of the scapula with substantially malrotated images. With the use of the 4 newly introduced semiquantitative and qualitative omometric criteria, which define an appropriate image, reliability of the measured parameters can be significantly improved.

Assessment of Screw Length of Proximal Humerus Internal Locking System (PHILOS) Plate for Proximal Humeral Fractures Using Three-Dimensional Computed Tomography Scan

Background

Screw perforation and varus collapse are common complications of treatment with a PHILOS (proximal humerus internal locking system) plate for proximal humerus fractures, which are associated with improper screw length selection and lack of medial column support. The purposes of this study were: (1) to measure the proper length of periarticular screws of the PHILOS plate in the humeral head, and (2) to determine what factors influence the screw length and implantation of the inferomedial support screw.

Material/Methods

Computed tomography (CT) images of the normal proximal humerus in 134 cases were retrospectively reviewed. The length of periarticular screws was measured using three-dimensional (3D) techniques. Intraobserver and interobserver reliability of measurement were evaluated using intraclass correlation coefficients (ICCs). Sex and body height influences on screw length and implantation of the inferomedial screw were analyzed.

Results

All measurements had excellent agreement (ICC>0.75). The screw length and implantation rate of the inferomedial screw were greater in males than in females. Positive correlations were observed between body height and screw length and implantation of the inferomedial screw (all P<0.001).

Conclusions

The screws were longer and the implantation rate was higher for inferomedial screws in males than in females, and were positively correlated with body height. Our data can be used as a reference for surgeons to reduce the number of times screws are changed intraoperatively and to reduce operation duration and minimize use of intraoperative fluoroscopy for proximal humerus fractures treated with the PHILOS plate.

Anatomic variations in glenohumeral joint: an interpopulation study

Background

This study focused on the unique aspect of investigating shoulder morphometric differences between 2 distinct populations.

Methods

We used 90 computed tomography images of cadaveric shoulders for this study; 45 scans belonged to the South African (SA) cohort (49.74 ± 15.4 years) and the rest were Swiss (CH; 53.8 ± 21 years). The articulating surfaces of the glenohumeral joint were extracted, and their morphometric features, such as head circular diameter, glenoid and humeral head radius of curvature, head height, and humeral height, were measured.

Results

The mean interpopulation difference in the circular diameter of the humerus was 2.0 mm (P = .017) and 1.86 mm (P > .05) in the anterior-posterior and superior-inferior directions, respectively. The difference in the radius of curvature between the populations was 1.17 mm (P = .037). The SA shoulders were found to be longer than the CH shoulders by 8.4 mm (P > .05). There was no significant difference in the glenoid radius of curvature. The SA shoulders had higher glenohumeral mismatch (P = .005) and lower conformity index (P = .001) in comparison to the CH shoulders.

Conclusion

This study presents anatomic differences between African and European glenohumeral articulating surfaces. The results suggest that the glenohumeral geometry is both gender and population specific, and future joint replacements may be designed to address these differences.

Glenoid morphology and the safe zone for protecting the suprascapular nerve during baseplate fixation in reverse shoulder arthroplasty

PURPOSE

The purpose of this study was to investigate glenoid morphology and define the safe zone for protecting the suprascapular nerve baseplate screw during baseplate fixation in reverse shoulder arthroplasty (RSA) in a Chinese population.

METHODS

Shoulder computed tomography (CT) scans from 56 subjects were retrospectively reviewed. Three-dimensional (3D) reconstruction was performed using Mimics software, and corresponding bony references were used to evaluate glenoid morphology. To standardize evaluation, the coronal scapular plane was defined. Safe fixation distances and screw placements were investigated by constructing a simulated cutting plane of the baseplate during RSA.

RESULTS

Mean glenoid height was 35.83 ± 2.95 mm, and width was 27.32 ± 2.78 mm, with significant sexual dimorphism (p < 0.01). According to the cutting plane morphology, the average baseplate radius was 13.84 ± 1.34 mm. The distances from the suprascapular notch and from two bony reference points at the base of the scapular spine to the cutting plane were 30.27 ± 2.77 mm, 18.39 ± 1.67 mm and 16.52 ± 1.52 mm, respectively, with a gender-related difference. Based on the clock face indication system, the danger zone caused by the suprascapular nerve projection was oriented between the two o'clock and eight o'clock positions in reference to the right shoulder.

CONCLUSIONS

Glenoid size and the safe zone for screw fixation during RSA were characterized in a Chinese population. Careful consideration of baseplate fixation and avoidance of suprascapular nerve injury are important for improved clinical outcome.

Three-dimensional quantitative analysis of humeral head and glenoid bone defects with recurrent glenohumeral instability

BACKGROUND

Although bone defects of the humeral head and glenoid could affect glenohumeral instability, bone loss has not been sufficiently evaluated. The purpose of this study was to quantify bone defects 3-dimensionally in cases with glenohumeral instability.

METHODS

Three-dimensional surface models of bilateral proximal humeri and glenoids were reconstructed from computed tomography scans of 90 patients with symptomatic, unilateral, recurrent glenohumeral instability. The left-side models were mirrored, and intact bone areas were matched to those of the right-side models. The volume, length, width, and depth of identified bone defects were assessed. After the values were corrected by patient height, the characteristics of the bone defects were evaluated.

RESULTS

Bone defects were present in 97.8% of the humeral heads and 96.7% of the glenoids, and women had significantly smaller bone defects than men did. The volume of humeral head defects had a mild correlation with that of glenoid defects. The number of traumatic episodes was not correlated with humeral head bone defects, but it was positively correlated with glenoid bone defects. Patients with recurrent dislocations had significantly deeper and larger Hill-Sachs lesions than the other cases.

CONCLUSION

Bone defects of the humeral head and the glenoid in cases with symptomatic traumatic glenohumeral instability were quantified 3-dimensionally using a computed tomography surface-matching technique. Almost all cases showed bone defects in the humeral head and glenoid compared with the intact shoulder, and such bone defects may be more common than previously reported. This study suggested that bipolar bone lesions are not always created by the same mechanism.

The Dimensions of the Scapula Glenoid in Japanese Rotator Cuff Tear Patients

BACKGROUND

Reverse total shoulder arthroplasty has become a widely accepted surgical procedure in Japan since the time when the implants were approved for use in 2014. There is a doubt, however, as to whether the implants designed for Western people are suitable for Japanese people, particularly for females of relatively small stature. The purpose of this study was to investigate the glenoid dimension, with special focus on the length after glenoid reaming, in Japanese rotator cuff tear patients.

METHODS

Fifty-six shoulders of 55 patients (35 males and 20 females; mean age, 63.8 years) were studied. Using the three-dimensional computed tomography images of the entire scapula before shoulder surgery, we measured the glenoid height and width, and calculated the correlation between these measurements and the patient's height. Further, we measured the anteroposterior length of the scapular neck at the subchondral bone and the length at 15 mm medial to the subchondral bone, to simulate both the glenoid width after reaming (width of the 'virtual reamed surface') and the space available for the end of the center post of a standard glenoid baseplate.

RESULTS

The average glenoid height and width were 35.8 mm and 28.1 mm in males and 30.8 mm and 23.4 mm in females, respectively. There was a significant correlation between patient height and glenoid size (glenoid height, r = 0.69; width, r = 0.75; p < 0.01). The mean value of the width of the virtual reamed surface was 27.0 mm in males and 22.5 mm in females. The mean anteroposterior length at 15 mm medial to the subchondral bone was 12.4 mm in males and 9.5 mm in females; the length was shorter than 8 mm in 6 female shoulders.

CONCLUSIONS

There was a significant correlation between patient height and glenoid size. Considering that the common diameter of the commercially available baseplates and their center posts is greater than 25 mm and 8 mm, respectively, these prosthetic parts would be too large, especially for the Japanese female glenoid. Given that the current results of Japanese shoulder dimensions are similar to those of Asian people, 'Asian size implants' should be developed.

Geometric Analysis of the Proximal Humerus in Elderly Japanese Patients: Implications for Implant Selection in Reverse Shoulder Arthroplasty

The implants used in reverse shoulder arthroplasty were originally designed for white patients; thus, they might not be optimal for smaller Asian patients. The selection of reverse shoulder arthroplasty systems is limited in Japan. The purpose of this study was to measure the geometry of the proximal humerus in elderly Japanese patients to inform implant selection according to humerus size. This study included 155 shoulders from 148 patients 50 years or older who underwent computed tomography for shoulder disorders other than arthritis and trauma. There were 67 male and 81 female patients with mean ages of 68 and 66 years, respectively. The humeral head diameter, head height, neck-shaft angle, neck diameters, and osteotomy diameters for 155° inclination implants were measured using surface models created from computed tomography scans. The mean diameter of head curvature, humeral head height, and neck-shaft angle were 48.2 mm, 19.8 mm, and 136° for male patients and 42.4 mm, 17.1 mm, and 136° for female patients, respectively. The mean mediolateral and anteroposterior neck diameters were 46.9 mm and 43.7 mm for men and 41.6 mm and 38.4 mm for women, respectively. The mean mediolateral and anteroposterior osteotomy diameters were 42.2 mm and 41.2 mm for male patients and 38.6 mm and 36.7 mm for female patients, respectively. There were significant differences between the sexes in all measurements except neck-shaft angle. Humeral implants with 155° inclination will not fit the humerus of smaller Japanese women. Thus, implants with anatomical inclination and an onlay humeral tray may be a better choice for smaller patients. [Orthopedics. 2017; 40(3):e485-e490.].

A three-dimensional comparative study on the scapulohumeral relationship in normal and osteoarthritic shoulders

BACKGROUND

Eccentric loading due to humeral translation is associated with worse clinical outcomes in hemiarthroplasty and total shoulder arthroplasty. The purpose of this study was to evaluate the 3-dimensional relationship of the humeral head to the scapula (scapulohumeral relationship) in nonpathologic shoulders and in shoulders with primary osteoarthritis.

MATERIALS AND METHODS

Three-dimensional reconstructions of computed tomography scans of 151 nonpathologic shoulders (control group) and 110 shoulders with primary glenohumeral arthritis (OA group) were analyzed by measuring the anterior-posterior, inferior-superior, and medial-lateral position of the humeral head in relation to the scapula. Shoulders were classified as centered (type A) or posteriorly subluxed (type B) according to the Walch classification of glenoid morphology. Reproducibility and differences in scapulohumeral relationship were statistically analyzed.

RESULTS

The scapulohumeral relationship could be determined reliably: the intraclass correlation coefficient ranged between 0.780 and 0.978; the typical error of measurement ranged between 2.4% and 5.0%. Both type A and type B shoulders showed significant posterior translation of the humeral head (P <.001). Type B shoulders had significantly more posterior translation than type A shoulders (P <.001). A tendency of inferior translation was noted, although with only marginal statistical significance (P = .051). In each morphology class, a medial deviation of the humeral head, representing a reduced glenohumeral distance, was measured (P <.001).

CONCLUSIONS

The main characteristics of primary glenohumeral osteoarthritis are posterior humeral head translation relative to the scapula, reduced glenohumeral distance, and a tendency toward inferior humeral head translation in both type A and type B shoulders.

Compared to X-ray, three-dimensional computed tomography measurement is a reproducible radiographic method for normal proximal humerus

BACKGROUND

Accurate comprehension of the normal humeral morphology is crucial for anatomical reconstruction in shoulder arthroplasty. However, traditional morphological measurements for humerus were mainly based on cadaver and radiography. The purpose of this study was to provide a series of precise and repeatable parameters of the normal proximal humerus for arthroplasty, based on the three-dimensional (3-D) measurements.

METHODS

Radiographic and 3-D computed tomography (CT) measurements of the proximal humerus were performed in a sample of 120 consecutive adults. Sex differences, two image modalities differences, and correlations of the parameters were evaluated. Intra- and inter-observer reproducibility was evaluated using intraclass correlation coefficients (ICCs).

RESULTS

In the male group, all parameters except the neck-shaft angle of humerus, based on 3-D CT images, were greater than those in the female group (P < 0.05). All variables were significantly different between two image modalities (P < 0.05). In 3-D CT measurement, all parameters expect neck-shaft angle had correlation with each other (P < 0.001), particularly between two diameters of the humeral head (r = 0.907). All parameters in the 3-D CT measurement had excellent reproducibility (ICC range, 0.878 to 0.936) that was higher than those in the radiographs (ICC range, 0.741 to 0.858).

CONCLUSIONS

The present study suggested that 3-D CT was more reproducible than plain radiography in the assessment of morphology of the normal proximal humerus. Therefore, this reproducible modality could be utilized in the preoperative planning. Our data could serve as an effective guideline for humeral component selection and improve the design of shoulder prosthesis.