Distinct Proximal Humeral Geometry in Chinese Population and Clinical Relevance

Shoulder Physiological Offset Parameters in Asian Populations-A Magnetic Resonance Imaging Study

Background/Objectives: Physical shoulder offset parameters (SOPs) play important roles in the diagnosis and treatment of shoulder diseases. However, there is little research analyzing SOPs in healthy shoulders using cross-sectional MRI images, especially in Asians. Therefore, this study aimed to establish physiological reference values of shoulder parameters for Asian populations. Methods: This was a retrospective imaging study using MRI images of the shoulder joints of 500 patients (mean age: 55.9 ± 14.0 years). We measured the following SOPs of the normal joint: HO, GO, lateral glenoidal humeral offset (LGHO), humeral shaft axis offset (HAO), and cortical offset (CO). In addition, the offset parameters were examined for associations with age, gender, side, and osteoarthritis. Results: The mean HO was 22.9 (±2.4) mm, the mean GO was 62.3 (±6.6) mm, the mean LGHO was 48.9 (±4.2) mm, the mean HAO was 25.2 (±2.8) mm, and the mean CO was 15.7 (±2.7) mm. Male patients exhibited significantly higher values across all SOPs compared to female patients. In addition, there was a significantly lower mean value for HAO in left shoulders (HAO: 24.7± 2.8 mm vs. 25.5 ± 2.8 mm, p = 0.011). There was a negatively significant correlation between age and all SOPs. No significant difference in mean values was noted between shoulders with osteoarthritis and non-osteoarthritis in any SOPs. Conclusions: Significant gender- and age-specific differences were noted for all measured SOPs. In addition, right shoulders did not show higher mean SOP values than left shoulders, except for HAO, suggesting that the contralateral joint is a reliable reference for surgical planning. These findings should be considered in shoulder surgery planning.

Three-Dimensional Morphometry Findings of the Proximal Humerus of the Indonesian Population

Background The design of implant components is the most critical prognostic factor in total shoulder arthroplasty as even minor discrepancies between the implant and the native anatomy can lead to failure. In this study, we aimed to describe the morphometry findings of the proximal humerus at our center, a national referral hospital located in the capital of Indonesia, serving a diverse population representing various Indonesian ethnicities. Methodology This observational, cross-sectional study included patients who had undergone upper extremity CT scans from January to December 2022. Demographic data such as age, sex, height, weight, body mass index, and ethnicity were collected from medical records. The measurements taken included the humeral head height (HHH), articular surface diameter (ASD), humeral head diameter (HHD), head-neck angle (inclination angle), and medial offset by CT scans. Results A total of 70 patients met the inclusion criteria. The average measurements were 14.3 ± 1.7 mm for HHH, 131.25° ± 5.15° for the head-neck angle (inclination angle), 40.50 ± 3.23 mm for the ASD, 44.86 ± 4.17 mm for the HHD, and 6.25 ± 1.93 mm for medial offset. HHH, ASD, and HHD showed significant differences between genders. Additionally, body height was significantly associated with HHH, ASD, and HHD. There was no significant measurement between ethnic groups in Indonesia. Conclusions A morphometric study of the proximal humerus revealed that the Indonesian population is vastly different than populations. Factors that need to be considered in selecting a shoulder implant include the patient's height, gender, and race. There was a direct correlation between ASD, HHD, and HHH. Body height had a direct correlation with ASD, HHD, and HHH. The proximal humerus measurements in the Indonesian population were not significantly different between ethnic groups.

Estimating elbow loading conditions through the motion behaviors of subchondral bone density during joint movements

Evaluating complicated stress across the elbow under joint motion remains difficult. Here, we aimed to evaluate the distribution of the subchondral bone density in the normal elbow bones and further characterize their spatial relationships during elbow motion to estimate the loading stress across the articular surface using three-dimensional computed tomography bone models. The normal elbow joint exhibited a consistent distribution pattern of subchondral bone density. High-density regions were distributed in the capitellum and posterior humeral trochlea, sagittal ridge of the ulnar trochlear notch and ulnar-volar side of the radial head. Motion analyses revealed that the high-density regions proximate with elbow flexion with forearm pronation in the radiocapitellar joint and in the fully extended position in the ulnohumeral joint. This reasonably reflects the stress acting on the joint surface under actual loading conditions. These findings suggest that daily activities involving lifting or carrying objects in these positions are stress-prone activities.

Study on Shoulder Joint Parameters and Available Supraspinatus Outlet Area Using Three-Dimensional Computed Tomography Reconstruction

Studies addressing the anatomical values of the supraspinatus outlet area (SOA) and the available supraspinatus outlet area (ASOA) are insufficient. This study focused on precisely measuring the SOA and ASOA values in a sample from the Chinese population using 3D CT (computed tomography) reconstruction. We analyzed CT imaging of 96 normal patients (59 males and 37 females) who underwent shoulder examinations in a hospital between 2011 and 2021. The SOA, ASOA, acromiohumeral distance (AHD), coracohumeral distance (CHD), coracoacromial arch radius (CAR), and humeral head radius (HHR) were estimated, and statistical correlation analyses were performed. There were significant sex differences observed in SOA (men: 957.62 ± 158.66 mm2; women: 735.87 ± 95.86 mm2) and ASOA (men: 661.35 ± 104.88 mm2; women: 511.49 ± 69.26 mm2), CHD (men: 11.22 ± 2.24 mm; women: 9.23 ± 1.35 mm), CAR (men: 37.18 ± 2.70 mm; women: 33.04 ± 3.15 mm), and HHR (men: 22.65 ± 1.44 mm; women: 20.53 ± 0.95 mm). Additionally, both SOA and ASOA showed positive and linear correlations with AHD, CHD, CAR, and HHR (R: 0.304-0.494, all p < 0.05). This study provides physiologic reference values of SOA and ASOA in the Chinese population, highlighting the sex differences and the correlations with shoulder anatomical parameters.

Accuracy of detecting burst of the lateral wall in intertrochanteric hip fractures with plain radiographs: Is postoperative CT necessary?

Background

Postoperative burst of the lateral femoral wall is thought to be the main predictor of reoperation for intertrochanteric fractures, which is routinely evaluated using plain radiographs. We retrospectively compared computed tomography (CT) scans and radiographs regarding the ability to detect burst of the lateral wall. We also investigated whether intramedullary nails may cause iatrogenic burst of the lateral wall.

Methods

From January 2010 to December 2021, patients aged 65 years and older who undergone intertrochanteric fractures treated with the proximal femoral nail antirotation 2 (PFNA-Ⅱ) were included. The incidence of burst of the lateral wall was evaluated with two different imaging modalities by two observers. Two rounds of evaluation were performed: (1) with plain radiographs alone; and (2) with CT scans combined with radiographs. Interobserver and intraobserver agreement (κ value) for evaluation of the lateral wall burst was assessed.

Results

A total of 1507 patients were included (362 males and 1145 females). Compared with radiographs alone (12.0 %, 181/1507 patients), a higher rate of lateral wall burst was found by CT scans combined with radiographs (72.9 %, 1098/1507 patients) for observer 1 at first reading (P < 0.001). Similar results were seen in other evaluations. Interobserver and intraobserver agreement was substantial for radiographs alone (κ, 0.659-0.727) and almost perfect for CT scans combined with radiographs (κ, 0.847-0.926).

Conclusions

Computed tomography combined with radiographs is superior to radiographs alone for detecting burst of the lateral wall after intertrochanteric fracture fixation. Additionally, PFNA-Ⅱ could cause iatrogenic burst of the lateral wall for intertrochanteric fractures in the elderly.

Design of well-matched end-structure of anatomical proximal femoral locking plate based on computer-assisted imaging combined with 3D printing technology: a quality improvement study

BACKGROUND

The extramedullary locking plate system was the common internal fixation method for hip fractures. However, common plates were poorly matched to femur, which was because they were designed based on anatomical parameters of the Western populations. Therefore, the aim was to design an end-structure of the anatomical proximal femoral locking plate that closely matched the anatomy of the Chinese population.

MATERIALS AND METHODS

From January 2010 to December 2021, consecutive patients aged 18 years and older who underwent a full-length computed tomography scan of the femur were included. The end-structure (male and female model) of the anatomical proximal femoral locking plate was designed based on anatomical parameters of femurs that were measured in three-dimensional space using computer-assisted virtual technology. The match degree between the end-structure and femur were evaluated. Inter-observer and intra-observer agreement for the evaluation of match degree was assessed. The matching evaluation based on a three-dimensional printing model was regarded as the gold standard to assess the reliability.

RESULTS

A total of 1672 patients were included, with 701 men and 971 women. Significant differences were seen between male and female for all parameters of the proximal femur (all P <0.001). All match degree of end-structure was over 90%. Inter-observer and intra-observer agreement was almost perfect (all kappa value, >0.81). The sensitivity, specificity, and percentage of correct interpretation of matching evaluation in the computer-assisted virtual model was all greater than 95%. From femur reconstruction to completion of internal fixation matching, the process takes about 3 min. Moreover, reconstruction, measurement, and matching were all completed in one system.

CONCLUSIONS

The results showed that based on the larger sample of femoral anatomical parameters, a highly matching end-structure of anatomical proximal femoral locking plate for Chinese population could be designed with use of computer-assisted imaging technology.

Stemless total shoulder arthroplasty using a novel multiplanar osteotomy and elliptical humeral head results in both improved early range of motion and radiographic center of rotation compared with standard total shoulder arthroplasty

BACKGROUND

Restoration of the native glenohumeral anatomy is an important consideration in obtaining optimal range of motion (ROM) after anatomic total shoulder arthroplasty (TSA). Recently, a new stemless TSA system has been developed that uses both a multiplanar osteotomy (MPO), to improve the surgeon's ability to restore humeral center of rotation (COR), and an elliptical humeral head to improve ROM. The purpose of our study was to compare the difference in early postoperative ROM and restoration of radiographic COR, between this stemless TSA and standard stemmed TSAs.

METHODS

This was a retrospective review of 50 consecutive primary TSAs performed by a single surgeon for glenohumeral osteoarthritis. The initial cohort underwent TSA with a standard stemmed humeral component with a circular humeral head (n = 25), whereas the subsequent cohort underwent stemless TSA using an MPO and an elliptical humeral head (n = 25). Postoperative data collection included active shoulder ROM as measured by goniometer, complications or revision surgery, and measurements of radiographic COR. Patients were assessed at 6 weeks, 12 weeks, 6 months, and 12 months after surgery. Change in COR was determined on postoperative radiographs by 2 fellowship-trained surgeons on 2 separate occasions. Intra- and interrater reliability were computed using intraclass correlation coefficients.

RESULTS

For both mean forward flexion (FF) and external rotation (ER), there was greater ROM in the MPO-elliptical group at all time points, which was statistically significant. Mean change in FF favored the MPO group at 6 and 12 weeks and was statistically significant and above the minimal clinically important difference (MCID): 6 weeks, standard -15.8° vs. MPO 8.4° (P = .004); 12 weeks, standard 6.4° vs. MPO 29.2° (P = .001). Mean change in ER favored the MPO group at 6 weeks and was statistically significant: standard 5.4° vs. MPO 14.0° (P = .02). There were no revision surgeries in either group. Average change in COR was 2.7 mm in the standard group and 1.8 mm in the MPO-elliptical group, which was statistically significant (P < .001). Number of patients with >3 mm of difference in COR was 10 (40%) in the standard group and 1 (5%) in the MPO-elliptical group, which was statistically significant (P = .002). Average intraclass correlation coefficient was 0.75, indicating good reliability within and between surgeon measurements.

CONCLUSION

The use of a multiplanar osteotomy and elliptical humeral head was associated with improved early range of motion and better reproduction of the radiographic COR compared with standard stemmed TSA.

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.

Glenoid Prosthesis Design Considerations in Anatomic Total Shoulder Arthroplasty

Total shoulder arthroplasty is an increasingly popular option for the treatment of glenohumeral arthritis. Historically, the effectiveness of the procedure has largely been determined by the long-term stability of the glenoid component. Glenoid component loosening can lead to clinically concerning complications including pain with movement, loss of function, and accumulation of debris which may require surgery to revise. In response, there has been a push to optimize the design of the glenoid prosthesis. Traditional contemporary glenoid components use pegs for fixation and are made entirely of polyethylene. Variations on the standard implant include keeled, metal-backed, hybrid, augmented, and inlay designs. There is a wealth of biomechanical and clinical studies that report on the effectiveness of these different designs. The purpose of this review is to summarize existing literature regarding glenoid component design and identify key areas for future research. Knowledge of the rationale underlying glenoid design will help surgeons select the best component for their patients and optimize outcomes following TSA.

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 Double-Circle System in the Greater Tuberosity: Using Radius to Predict Rotator Cuff Tear

OBJECTIVE

In this study we concerned on the morphological characteristics of the greater tuberosity of humerus and proposed the double-circle radius ratio as a new predictor for the diagnosis of rotator cuff tears.

METHODS

This was a retrospective study and patients who visited our hospital and were diagnosed with or without rotator cuff tears via magnetic resonance imaging from January 2018 to July 2021 were enrolled and classified into two groups respectively. In a standard anteroposterior view, the radius of the best-fit circle of humeral head and the radius of the concentric circle passing through the most lateral edge of the greater tuberosity were measured in each shoulder. The ratio of these two radiuses was named as the double-circle radius ratio. Angular parameters including the greater tuberosity angle and the critical shoulder angle were also measured in the anteroposterior view. Independent samples t tests and chi-square tests were used to find significant differences between groups. Significant associations between those measured variables and demographic characteristics were analyzed with simple linear regression analysis. Receiver operating characteristic curves were pictured to determine applied cutoff values by using Youden index. Multivariable-adjusted analysis for the occurrence of rotator cuff tears was carried out by using multiple logistic regression analysis. For all tests a p value of <0.05 was considered statistically significant.

RESULTS

One hundred and twelve shoulders with rotator cuff tears and 42 shoulders without rotator cuff tears were included. The mean value of the double-circle radius ratio was significantly larger in shoulders with rotator cuff tears (1.42 ± 0.09 vs. 1.30 ± 0.07, P = 0.000). With simple linear regression analysis, the radiuses of the humeral head and the greater tuberosity were significantly associated with heights and weights. In receiver operating characteristic curves, the largest area was found under the curve of the double-circle radius ratio as 0.846 (95% CI, 0.781-0.911; P = 0.000) with an applied cutoff value as 1.38 (sensitivity, 70.5%; specificity, 88.1%). Multivariable-adjusted analysis showed that a value of the double-circle radius ratio >1.38 resulted in 11.252-fold odds of developing rotator cuff tears (95% CI, 3.388-37.368; P = 0.000).

CONCLUSION

The double-circle radius ratio is significantly larger in patients with rotator cuff tears and could be regarded as an eligible predictor for rotator cuff tears.

How can medial support for proximal humeral fractures be achieved when positioning of regular calcar screws is challenging? Slotting and off-axis fixation strategies

BACKGROUND

Achieving medial support for proximal humeral fractures (PHFs) by regular calcar screw positioning is challenging when the humeral head is small or locking plates are placed distally, as there are unable inserted calcar screws into the humeral head. We aimed to investigate the suitability of the 2 strategies, slotting calcar screw (SCS) and off-axis calcar screw (OCS), to achieve medial support for PHFs.

METHODS

Regular calcar screw (RCS), SCS, OCS, and noncalcar screw (NCS) were tested via mechanical experiments and finite element analysis (FEA), using synthetic bones for biomechanical comparisons. All PHFs treated in our hospital from March 2017 to March 2019 were reviewed. The patients were divided into 3 groups based on the calcar screw fixation: RCS, SCS, and OCS. The postoperative varus collapse (neck-shaft angle changed to less than 120°) and Disabilities of the Arm, Shoulder and Hand (DASH) scores were recorded.

RESULTS

The properties of RCS, SCS, and OCS against the torsion and varus force were superior to those of NCS, whereas the stiffness of SCS, OCS, and RCS were similar. FEA predicted lower peri-screw strains in the OCS and SCS than in the RCS, indicating a lower risk of cut-out. Patients (n = 125; 75 female, 50 male) aged 55.9 ± 13.0 years were evaluated. Compared with the RCS (5/55), varus collapse incidences were not significantly higher following SCS (0/29, P = .094) or OCS (3/41, P = .756), and neither were DASH scores (P = .867 and .736, respectively).

CONCLUSIONS

This study is a preliminary study demonstrating that the SCS and OCS fixation strategies could be useful alternatives when regular calcar fixation is not possible using the plate at hand.

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.

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.

Three-dimensional morphological analysis and clinical application of ankle joint in Chinese population based on CT reconstruction

PURPOSE

To study the anatomical features of the ankle joint in Chinese northeast healthy adults and provide accurate data for the design of the total ankle arthroplasty (TAA) prosthesis.

METHODS

Computer tomography (CT) images from 156 healthy subjects, 86 males and 70 females, were collected and reconstructed through Mimics software. The 3D morphology of the distal tibia/fibula section and the whole talar was analyzed by measuring 28 parameters including maximal tibial thickness (MTiTh), anterior-posterior inclination angle, trochlea tali width (TaW), distal tibial width (TiW) and trochlea tali arc chode length (TaAL) and calculating MTiTh/TiW, TaAL/TaW. Gender difference and accuracy of CT images were evaluated. The measurements were compared with previously reported data from Caucasian subjects and Asian subjects. Statistical analysis was conducted by independent-samples t test through SPSS software.

RESULTS

(1) Twenty two out of the 28 parameters were found significantly different between males and females. Most of the parameters in males were found larger than that in females (p < 0.05). (2) The difference was found larger in comparison with the Caucasian subject groups than that with Asian subject groups. (3) All the selected 11 parameters measured by CT images were found to be smaller than those by X-ray images (p < 0.05).

CONCLUSION

The morphological parameters were found different between the Caucasian and Chinese northeast populations. Precise data of the ankle joint morphology were provided for the design and clinical application of TAA in the Chinese population.

The Walch type B humerus: glenoid retroversion is associated with torsional differences in the humerus

BACKGROUND

The Walch type B glenoid has the hallmark features of retroversion, joint subluxation, and bony erosion. Although the type B glenoid has been well described, the morphology of the corresponding type B humerus is poorly understood. As such, the aim of this imaging-based anthropometric study was to investigate humeral torsion in Walch type B shoulders.

METHODS

Three-dimensional models of the full-length humerus were generated from computed tomography data for the Walch type B group (n = 59) and for a control group of normal nonarthritic shoulders (n = 59). An anatomic humeral head-neck plane was created and used to determine humeral torsion relative to the epicondylar axis. Measurements were repeated, and intraclass correlation coefficients were calculated.

RESULTS

The type B humeri had significantly (P < .001) less retrotorsion (14° ± 9°) than the control group (36° ± 12°) relative to the epicondylar axis. Male and female individuals within the control group showed statistically significant differences in humeral torsion (P = .043), which were not found in the type B group. Inter-rater reliability showed excellent agreement for humeral torsion (intraclass correlation coefficient, 0.962). A subgroup analysis between Walch type B2 and B3 shoulders showed no significant differences in any of the humeral or glenoid parameters.

CONCLUSION

The Walch type B humerus has significantly less retrotorsion than non-osteoarthritic shoulders. At present, it is unknown whether the altered humeral retrotorsion is a cause or effect of the type B glenoid. In addition, it is unknown whether surgeons should be reconstructing type B2 humeral component version to pathologic torsion or to nonpathologic population means to optimize arthroplasty survivorship.

Measurement of talar morphology in northeast Chinese population based on three-dimensional computed tomography

Morphological data of talus are important for the design of talar prostheses. The talar morphology of Chinese population has been rarely reported. This study adopted a three-dimensional (3D) measurement approach to provide accurate data for the anatomical morphology of talus in Northeast Chinese population and compared it with that of foreigners.One hundred forty-six healthy subjects form Northeast China underwent computed tomography (CT) arthrography. 3D digital talar model was reconstructed and thirteen morphological parameters were measured through Mimics and Magics software. Length and breadth indexes of total talus, trochlea, medial and lateral malleolus articular surface were mainly selected. Statistical analysis was conducted by independent-samples and paired-samples t test through SPSS software.All the indexes were normally distributed. No significant difference between left and right talus was identified in either males or females (P > .05). Most of the indexes showed significant sexual differences except the radian of lateral malleolus articular surface and the posterior breadth of trochlea (P < .05). The talar anatomy of Chinese subjects is different from the published data in other populations.The promising approach adopted in this study addresses some inconvenience with previous conventional methods on cadaver specimens. The geometric parameters of talus in Chinese population differ from those in other populations. The talar measurements and morphology analysis in this study suggest that population characteristics should be taken into account. This study will provide references for the design of talar prostheses in Chinese population.

Regional Distribution of Articular Cartilage Thickness in the Elbow Joint: A 3-Dimensional Study in Elderly Humans

During elbow procedures, reconstruction of the joint (including the articular cartilage) is important in order to restore elbow function; however, the regional distribution of elbow cartilage is not completely understood. The purpose of the present study was to investigate the 3-dimensional (3-D) distribution patterns of cartilage thickness of elbow bones (including the distal part of the humerus, proximal part of the ulna, and radial head) in order to elucidate the morphological relationship among them.

The Circle-Fit Method Helps Make Reliable Cortical Thickness Measurements Regardless of Humeral Length

Background

Although proximal humerus strength/quality can be assessed using cortical thickness measurements (eg, cortical index), there is no agreement where to make them. Tingart and coworkers used measurements where the proximal endosteum becomes parallel, while Mather and coworkers used measurements where the periosteum becomes parallel. The new circle-fit method (CFM) makes 2 metaphyseal (M1-M2) and 6 diaphyseal (D1-D6) measurements referenced from humeral head diameter (HHD). However, it is unknown whether these locations correlate to humeral length (HL). Accordingly, we asked: (1) Does HHD, Tingart distance, and Mather distance correlate with HL? (2) What is the location of HHD, Tingart distance, and Mather distance as a percentage of HL? and (3) Which CFM D1-D6 locations correlate with Tingart and Mather distances?

Materials and Methods

Measurements made on cortical thickness (CT) scout views of 19 humeri (ages: 16-73 years) included HHD, distances from the superior aspect of the humerus to proximal Tingart and Mather locations, and HL.

Results

Intraclass correlation was excellent for CFM-HHD, poor for Tingart, and moderate for Mather. The CFM-HHD had a stronger correlation to HL than Tingart and Mather. Mean HHD was 15.5% (0.9%) of HL while Tingart was 27.0% (4.1%) and Mather was 23.2% (3.8%). Tingart distance corresponded to D2/D3 CFM locations while the Mather distance was similar to D1/D2.

Discussion

The CFM reliably correlates with HL and provides a stronger correlation and less variance between specimens than the Tingart or Mather Methods.

Conclusions

Because the CFM produces reliable percent of HL locations, it should be used to define locations for obtaining biomechanically relevant CT measurements such as cortical index. Stronger correlations of these CFM-based measurements with proximal humerus strength will be important for developing advanced algorithms for fracture treatment.

Predictors of Pain and Discomfort Associated with CT Arthrography of the Shoulder

RATIONALE AND OBJECTIVES

The objective of this study was to investigate predictors of pain associated with computed tomographic arthrography of the shoulder.

MATERIALS AND METHODS

Before shoulder arthrography, all participants were assessed with the Hospital Anxiety and Depression Scale (HADS) and the World Health Organization Quality of Life Short Version Instrument (WHOQOL-BREF). The participants were nonrandomized into two groups: the anesthesia group, who underwent prior local infiltration anesthesia before shoulder arthrography, and the nonanesthesia group, who did not undergo prior local infiltration anesthesia. The pain levels at intraprocedure, at 1, 2, 6, and 12 hours, and at 1 and 2 days after injection were assessed by using a visual analog scale. Univariate and multivariate generalized linear model analyses were conducted.

RESULTS

Sixty participants in the anesthesia group and 60 participants in the nonanesthesia group were included. The pain level at intraprocedure (3.37 ± 1.94 in the anesthesia group and 3.20 ± 1.34 in the nonanesthesia group) was the highest of the whole pain course. The psychological domain (P = .0013) of WHOQOL-BREF, gender (P = .042), body mass index (P = .0001), and the total number of reinsertion and redirection of needle (P< .0001) were independent predictors of arthrography-related pain.

CONCLUSIONS

The pain associated with shoulder computed tomographic arthrography depends on the psychological domain of WHOQOL-BREF, gender, body mass index, and the total number of reinsertion and redirection of needle.

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.

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.