Diagnostic performance of long head of biceps tendon tears on MRI: systematic review and meta-analysis.

OBJECTIVES: The purpose of this meta-analysis was to determine the diagnostic performance of conventional MRI and MR arthrography for tendinosis, and partial and complete tears of the long head of the biceps tendon (LHBT) using arthroscopy as the reference standard. MATERIALS AND METHODS: A systematic review was performed using predefined data fields in PubMed, and all articles published from January 2000 up to April 2022 were retrospectively pooled and reviewed. Six MRI studies on complete tear (n = 555) and ten studies on partial tear/tendinosis (n = 2487) were included in the analysis. Two of the included studies in each group investigated the use of MR arthrography. The data sets were analyzed using a univariate approach with the DerSimonian and Laird random effects model and the proportional hazards model. RESULTS: MRI shows high specificities in diagnosing complete tears of the LHBT ranging from 93.0 to 99.0%. Diagnostic sensitivity was more heterogeneous ranging from 55.9 to 90.0%. The overall negative likelihood ratio was 0.29 (95% CI: 0.17-0.50) and the overall positive likelihood ratio was 37.3 (95% CI: 11.9-117.4). The mean sensitivity in diagnosing partial tear/tendinosis of the LHBT was 67.8% (95% CI: 54.3-78.9%) and the specificity was 75.9% (95% CI: 63.6-85.0%), resulting in a balanced accuracy of 71.9%. The overall negative likelihood ratio was 0.44 (95% CI: 0.32-0.59) and the overall positive likelihood ratio was 2.64 (95% CI: 1.91-3.65). CONCLUSION: MRI is highly specific for the diagnosis of complete tears of the LHBT, whereas diagnostic sensitivity was more heterogeneous. The diagnosis of partial tears and/or tendinosis of the LHBT remains challenging on MRI, which may warrant complementary clinical examination or other imaging modalities to increase diagnostic confidence in equivocal cases. CLINICAL RELEVANCE STATEMENT: Conventional MRI and MR arthrography have high diagnostic performance for complete tendon tear when compared to arthroscopy. The diagnosis of tendinosis/partial tears remains challenging and may require comparison with clinical tests and other imaging modalities. KEY POINTS: •There is no clear consensus regarding the primary imaging modality for the evaluation of LHBT disorders. •Conventional MRI and MR arthrography are highly specific in diagnosing complete tears of the LHBT. •Diagnosis of partial tears/tendinosis of the LHBT on conventional MRI and MR arthrography remains a diagnostic challenge.

Temporizing cast immobilization is a safe alternative to external fixation in ankle fracture-dislocation while posterior malleolar fragment size predicts loss of reduction: a case control study.

BACKGROUND: To determine if temporizing cast immobilization is a safe alternative to external fixator (ex-fix) in ankle fracture-dislocations with delayed surgery or moderate soft-tissue injury, we analysed the early complications and re-dislocation rates of cast immobilization in relation to ex-fix in patients sustaining these injuries. METHODS: All skeletally mature patients with a closed ankle fracture-dislocation and a minimum 6-months follow-up treated between 2007 and 2017 were included. Baseline demographics, comorbidities, injury description, treatment history and complications were assessed. RESULTS: In 160 patients (94 female; mean age 50 years) with 162 ankle fracture-dislocations, 35 underwent primary ex-fix and 127 temporizing cast immobilizations. Loss of reduction (LOR) was observed in 25 cases (19.7%) and 19 (15.0%) were converted to ex-fix. The rate of surgical site infections (ex-fix: 11.1% vs cast: 4.6%) and skin necrosis (ex-fix: 7.4% vs cast: 6.5%) did not differ significantly between groups (p = 0.122 and p = 0.825). Temporizing cast immobilization led to an on average 2.7 days earlier definite surgery and 5.0 days shorter hospitalization when compared to ex-fix (p < 0.001). Posterior malleolus fragment (PMF) size predicted LOR with ≥ 22.5% being the threshold for critical PMF-size (p < 0.001). CONCLUSION: Temporizing cast immobilization was a safe option for those ankle fracture-dislocations in which immediate definite treatment was not possible. Those temporized in a cast underwent definite fixation earlier than those with a fix-ex and had a complication rate no worse than the ex-fix patients. PMF-size was an important predictor for LOR. Primary ex-fix seems appropriate for those with ≥ 22.5% PMF-size. TRIAL REGISTRATION: The study does not meet the criteria of a prospective, clinical trial. There was no registration.

Clinical and radiographic outcomes of an all-polyethylene fluted central peg glenoid component, implanted utilizing an off-label, uncemented technique, at a minimum 5-year follow-up.

BACKGROUND: Glenoid component loosening remains an important concern in anatomic total shoulder arthroplasty. The aim of this study was to evaluate the clinical and radiographic results of a fully uncemented all-polyethylene fluted central peg bone-ingrowth glenoid component at a minimum 5-year follow-up. METHODS: Thirty-five shoulders in 31 patients (mean age, 73 years) with a mean follow-up of 100 months were retrospectively evaluated at an early and mid-term time point for Constant score (CS). Computed tomography visualized glenoid component fixation at both time points. RESULTS: Mean CS improved from 40 preoperatively to 66 postoperatively at latest follow-up (P < .001). A mean CS of 74 at early follow-up remained consistent with a mean CS of 66 at latest follow-up (P = .158), with only strength demonstrating a decrease over time (P < .001). An initial osseointegration rate of 81% at early follow-up decreased to 71% at latest follow-up with 74% of the shoulders demonstrating progressive radiolucent lines, resulting in a radiographic loosening rate of 31%. Of the 35 shoulders, 4 were revised (survival rate of 88%), of which 2 due to symptomatic aseptic loosening. CONCLUSIONS: Uncemented fixation of an all-polyethylene central peg bone-ingrowth glenoid was associated with satisfactory clinical and radiographic scores, and an acceptable revision rate at mid- to long-term follow-up. Despite initial bony osseointegration in the majority of cases, radiographic loosening over time remains a concern, potentially jeopardizing long-lasting fixation of this type of glenoid component when implanted in an off-label uncemented fashion.

Coracoacromial morphology: a contributor to recurrent traumatic anterior glenohumeral instability?

BACKGROUND: Although scapular morphology contributes to glenohumeral osteoarthritis and rotator cuff disease, its role in traumatic glenohumeral instability remains unknown. We hypothesized that coracoacromial and glenoid morphology would differ between healthy subjects and patients with recurrent traumatic anterior shoulder instability. METHODS: Computed tomography scans of 31 cadaveric control scapulae and 54 scapulae of patients with recurrent traumatic anterior shoulder instability and Hill-Sachs lesions were 3-dimensionally reconstructed. Statistical shape modeling identified the modes of variation between the scapulae of both groups. Corresponding measurements quantified these modes in relation to the glenoid center (linear offset measures), defined by the best-fit circle of the inferior glenoid, or the glenoid center plane (angles), which bisects the glenoid longitudinally. Distances were normalized for glenoid size. RESULTS: Compared with controls, the unstable coracoids were shorter (P = .004), with a more superior and medial offset of the tip (mean difference [MD], 7 and 3 mm, respectively; P < .001) and an origin closer to the 12-o'clock position (MD, 6°; P < .001). The unstable scapular spines originated closer to the 9-o'clock position (MD, 4°; P = .012), and the unstable acromions were more vertically oriented (MD, 6°; P < .001). The unstable glenoids had an increased height-width index (MD, 0.04; P = .021), had a flatter anterior-posterior radius of curvature (MD, 77 mm; P < .001), and were more anteriorly tilted (MD, 5°; P = .005). CONCLUSIONS: Coracoacromial and glenoid anatomy differs between individuals with and without recurrent traumatic anterior shoulder instability. This pathologic anatomy is not addressed by current soft-tissue stabilization procedures and may contribute to instability recurrence.

Conversion of painful tibiotalocalcaneal arthrodesis to total ankle replacement using a 3-component mobile bearing prosthesis.

BACKGROUND: The aim of this study was to assess the short-term clinical and radiographic outcomes in patients who underwent conversion of a painful tibiotalocalcaneal arthrodesis to a total ankle replacement. METHODS: Six patients with painful ankle arthrodesis after tibiotalocalcaneal arthrodesis were included in this study. In all patients, conversion to total ankle replacement was performed using a 3rd-generation, non-constrained, cementless three-component prosthesis. The outcomes were analyzed at a mean follow-up of 3.4±1.9years (range 1.0-6.5). RESULTS: One patient with painful arthrofibrosis underwent two open arthrolysis procedures at 1.2 and 5.6 years post index surgery, respectively. No revision of tibial or talar prosthesis components was necessary in this study. All patients reported significant pain relief and significant improvement in functional status. CONCLUSION: In the present study, the conversion of a painful ankle arthrodesis following tibiotalocalcaneal arthrodesis to a total ankle replacement was a reliable surgical treatment.

Guidelines for humeral subluxation cutoff values: a comparative study between conventional, reoriented, and three-dimensional computed tomography scans of healthy shoulders.

BACKGROUND: The humeral subluxation index (HSI) is frequently assessed on computed tomography (CT) scans in conditions of the shoulder characterized by humeral displacement. An arbitrarily set HSI cutoff value of 45% for anterior subluxation and 55% for posterior subluxation has been widely accepted. We studied whether mean values and thresholds of humeral subluxation, in relation to the glenoid and scapula, were influenced by different imaging modalities. METHODS: The HSIs referenced to the scapula (SHSI) and glenoid (GHSI) were compared between conventional CT scans, CT scans reoriented into the corresponding reference plane (ie, scapular plane for the SHSI and glenoid center plane for the GHSI), and 3-dimensional (3D) CT reconstructions of 120 healthy shoulders. The 95% normal range determined the cutoff values of humeral subluxation. RESULTS: The SHSI thresholds for conventional, reoriented, and 3D CT scans were 33%-61%, 44%-68%, and 49%-61%, respectively. A different mean SHSI was found for each imaging modality (conventional, 47%; reoriented, 56%; 3D, 55%; P ≤ .014), with the conventional SHSI showing an underestimation in 89% of the cases. GHSI thresholds for conventional, reoriented, and 3D CT scans were 40%-61%, 44%-56%, and 46%-54%, respectively. The mean GHSI did not differ between each imaging modality (conventional, 51%; reoriented, 50%; 3D, 50%; P = .146). CONCLUSIONS: The SHSI and GHSI are susceptible to different imaging modalities with consequently different cutoff values. The redefined HSI cutoff values guide physicians in the evaluation of humeral subluxation in conditions characterized by humeral displacement, depending on the available image data.

The critical acromial point: the anatomic location of the lateral acromion in the critical shoulder angle.

BACKGROUND: Acromioplasty has been proposed as a means of altering elevated critical shoulder angles (CSAs). We aimed to localize the critical acromion point (CAP) responsible for the acromial contribution of the CSA and determine whether resection of the CAP can alter the CSA to a normal range. METHODS: The CAP and 3-dimensional (3D) CSAs were determined on 3D computed tomography reconstructions of 88 cadaveric shoulders and compared with corresponding CSAs on digitally reconstructed radiographs. The position of the CAP was fluoroscopically isolated in 20 of these specimens and the resulting fluoroscopic CSA compared with the corresponding 3D CAP and 3D CSA. We investigated the CSA before and after a virtual acromioplasty of 2.5 and 5 mm at the CAP in specimens with a CSA greater than 35°. RESULTS: The mean CAP was 21% ± 10% of the acromial anterior-posterior length from the anterolateral corner. There was no difference between the mean 3D CSA and the CSA on digitally reconstructed radiographs (32° vs 32°, P = .096). No difference between the mean fluoroscopic CSA and 3D CSA was found (31° vs 31°, P = .296). A 2.5-mm acromial resection failed to reduce the CSA to 35° or less in 7 of 13 shoulders, whereas a 5-mm resection reduced the CSA to 35° or less in 12 of 13. CONCLUSION: The CAP was localized to the anterolateral acromial edge and was easily identified fluoroscopically. A 5-mm acromial resection was effective in reducing the CSA to 35° or less. These data can guide surgeons in where and how to alter the CSA if future studies demonstrate a clinical benefit to surgically modifying this radiographic parameter.

Clinical and sonographic evaluation of subpectoral biceps tenodesis with a dual suture anchor technique demonstrates improved outcomes and a low failure rate at a minimum 2-year follow-up.

INTRODUCTION: The purpose of this study was to evaluate the clinical outcomes and integrity of an open subpectoral biceps tenodesis using a dual suture anchor construct. MATERIALS AND METHODS: Patients with at least 2 years of follow-up were retrospectively evaluated for simple shoulder test (SST), American Shoulder and Elbow Surgeons (ASES) score, and visual analog scales (VAS) for pain, function and satisfaction. A physical exam assessed shoulder range of motion and elbow strength. Ultrasonography visualized construct integrity. RESULTS: Of 43 eligible patients, 36 completed questionnaire evaluation and 22 completed an additional physical examination. Indications included superior labral anterior-posterior (SLAP) lesions (4), partial thickness tears (6), instability (6), and tenosynovitis of the biceps tendon (20). Eighteen patients (50%) had an associated rotator cuff tear. Patient-reported outcomes improved pre- vs postoperatively: ASES score (45.4 vs 78.6, P < 0.001), SST (5.1 vs 9.6, P < 0.001), pain-VAS (4.8 vs 2.0, P < 0.001), and function-VAS (4.9 vs 2.3, P < 0.001). Satisfaction-VAS was 8.3 postoperatively. Patient-reported outcomes did not differ for patients with an associated rotator cuff tear compared to those without (P ≥ 0.427). None of the physical exam measures were lower on the operative side compared to the healthy side (P ≥ 0.516). Sonographic evaluation revealed preserved integrity of the tenodesis construct in all cases. No complications were noted. CONCLUSIONS: Subpectoral biceps tenodesis utilizing a dual suture anchor technique is a treatment option for SLAP lesions, partial thickness tears, subluxation, and tenosynovitis of the long head of the biceps with high rates of postoperative patient satisfaction, a low failure rate, and improved outcome scores. The presence of a concomitant rotator cuff tear did not influence clinical outcomes.

The three-dimensional glenohumeral subluxation index in primary osteoarthritis of the shoulder.

BACKGROUND: Assessment of glenohumeral subluxation is essential in preoperative planning of total shoulder arthroplasty. The purpose of this study was to evaluate a 3-dimensional (3D) glenohumeral subluxation index (GHSI) in shoulders with primary osteoarthritis (OA) and its relationship with morbid glenoid retroversion. METHODS: The 3D computed tomography reconstructions of 120 healthy shoulders and 110 shoulders with primary glenohumeral arthritis (OA group), classified according to Walch's glenoid morphology, were analyzed. The 3D GHSI was assessed by measuring posterior decentering of the humeral head in relation to the native glenoid in each subject, and its correlation to morbid glenoid version was calculated. RESULTS: The reproducible 3D GHSI (intraclass correlation coefficients ≥ 0.842) showed a posterior decentering of the humeral head in the OA population and in each type of glenoid morphology (P ≤ .005). A moderate correlation was observed in the OA group (r = -0.542; P < .001), but weak linear relationships were found for different glenoid morphology types (r between 0.041 and -0.307). Type A shoulders (r = -0.375; P = .006) correlated better than type B shoulders (r = -0.217; P = .104). After shoulders were subcategorized according to a threshold for 3D subluxation, the posteriorly subluxated group increased its correlation (r = -0.438; P < .001), whereas the centered shoulders still exhibited no relationship (r = -0.192; P = .329). CONCLUSIONS: Posterior humeral head decentering in relation to the native glenoid is present in each glenoid morphology type. Grouping measures according to morphology type and 3D subluxation showed at best moderate correlations between morbid version and 3D GHSI.

Towards standardised definitions of shoulder arthroplasty complications: a systematic review of terms and definitions.

INTRODUCTION: A transparent, reliable and accurate reporting of complications is essential for an evidence-based evaluation of shoulder arthroplasty (SA). We systematically reviewed the literature for terms and definitions related to negative events associated with SA. MATERIALS AND METHODS: Various biomedical databases were searched for reviews, clinical studies and case reports of complications associated with SA. Any general definition of a complication, classification system, all reported terms related to complications and negative events with their definitions were extracted. Terms were grouped and organised in a hierarchical structure. Definitions of negative events were tabulated and compared. RESULTS: From 1086 initial references published between 2010 and 2014, 495 full-text papers were reviewed. Five reports provided a general definition of the term "surgical complication" and 29 used a classification system of complications. A total of 1399 extracted terms were grouped based on similarities and involved implant or anatomical parts. One hundred and six reports (21.4%) defined at least one negative event for 28 different terms. There were 64 definitions related to humeral or glenoid loosening, and 25 systems documenting periprosthetic radiolucency. Other definitions considered notching, stress shielding, implant failure and tuberosity malposition. CONCLUSIONS: A clear standardised set of SA complication definitions is lacking. Few authors reported complications based on definitions mainly considering radiological criteria without clinical parameters. This review should initiate and support the development of a standardised SA complication core set.

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.

Accuracy of the glenohumeral subluxation index in nonpathologic shoulders.

BACKGROUND: Correction of posterior humeral subluxation, measured by the humeral subluxation index (HSI) according to Walch, is necessary in total shoulder arthroplasty to prevent early loosening. The 3-dimensional (3D) measurement of the shoulder is becoming well accepted and common practice as it overcomes positional errors to which 2-dimensional (2D) glenohumeral measurements are prone. The first objective was to describe the HSI in a nonpathologic population with the 2D HSI according to Walch and a newly described 3D HSI method. The second objective was to compare both measuring methods with each other. METHODS: In 151 nonpathologic shoulders, the 2D HSI was measured on the midaxial computed tomography scan cut of the scapula. The 3D HSI, based on the native glenoid plane, was defined as [formula in text], in which X is the projection of the center of the humeral head to the anteroposterior axis of the glenoid fossa and R is the radius of the humeral head. Both measuring methods were compared with each other. Correlation was determined. Interobserver and intraobserver reliability of the 3D HSI was measured. RESULTS: The mean 3D HSI (51.5% ± 2.7%) was significantly (P < .001) more posterior than the mean 2D HSI (48.7% ± 5.2%), with a mean difference of 2.9% ± 5.6%. No correlation was found between the 2D and 3D HSI. The interobserver and intraobserver reliability was excellent. CONCLUSION: The 2D HSI seems to underestimate the humeral subluxation compared with a 3D reliable equivalent.

Three-dimensional computed tomography scan evaluation of the pattern of erosion in type B glenoids.

BACKGROUND: Type B glenoids according to Walch are subclassified into a group with no posterior erosion (B1) and a group with important posterior erosion (B2) based on 2-dimensional axial computed tomography (CT) scan images. Three-dimensional (3D) CT scan reconstruction seems to improve the accuracy of the measurement of erosion because of its independence from positional errors. The aim is to quantify the direction and amount of posterior erosion of type B glenoids using a reproducible 3D measuring technique. METHODS: We performed 3D reconstruction of 72 type B glenoids (24 type B1 glenoids and 48 type B2 glenoids) using Mimics (Materialise, Haasrode, Belgium). The native glenoid plane and intermediate glenoid plane were determined by use of 3-Matic (Materialise). The normal glenoid version, eroded retroversion, and difference in retroversion were measured. Next, the maximum erosion and its orientation were quantified. RESULTS: There was always minimum erosion of 1.7 mm, and the mean erosion was 4.2 mm. There was a significant difference between the mean erosion in type B1 glenoids (3.5 mm) and type B2 glenoids (4.5 mm) (P = .019). The mean orientation of the erosion was mostly to the posteroinferior side (119°; SD, 26.8). There was a significant difference between the mean orientation in type B1 glenoids (132°; SD, 25.2) and type B2 glenoids (113°; SD, 25.5) (P = .004). CONCLUSIONS: With the use of this newly developed reproducible measuring technique, the maximum erosion in type B glenoids can be adequately quantified. All glenoids showed signs of important erosion. Because the orientation of the maximum erosion in type B1 glenoids is situated more inferiorly, the 2-dimensional CT scan technique can be insufficient to evaluate this erosion.

Treating pathological metastatic fractures of the humerus by compound osteosynthesis: a retrospective cohort study.

Background: The number of malignant tumors is increasing as are bone metastases, such as those in the humerus. Arm function is important for an independent everyday life. In this study, compound osteosynthesis of metastatic fractures of the humerus is examined for its suitability in light of the competing risk of death. Methods: This retrospective monocentric study includes a cohort of tumor patients who underwent primary compound osteosynthesis for pathological humeral fractures. The main endpoint was the continued existence of compound osteosynthesis using competing risk analysis to contrast failure and death. Failure was defined as mechanical failure of the osteosynthesis construct like refracture or plate-and-screw dislocation or loosening, which provides an indication for reintervention. Other complications are also described. Results: We included 36 consecutive patients (64% male, mean age: 71.6 yr) from September 2007 to October 2020. In 58% of the cases, the left humerus was fractured. Lung carcinoma was the most common cause of bone metastases (27.8%). Compound osteosynthesis was performed with a median delay of 5 days after diagnosis of the pathologic fracture. Postoperative complications occurred in 7 of the 36 patients (19.4%): radial nerve palsy (n = 3), postoperative hematoma (n = 2), refracture (n = 2), and screw loosening (n = 1). Few mechanical failures (8.3%) occurred within the first year; only 1 patient needed revision of the osteosynthesis (2.8%). Median patient survival after compound osteosynthesis was 26.6 weeks. Competing risk analysis showed that for up to 2 years, the risk of death is clearly dominant over the risk of osteosynthesis failure from surgery. Conclusion: Our study shows that compound osteosynthesis of the humerus is a suitable option for patients with pathologic humerus fractures. Compound osteosynthesis of the humerus usually survives the duration of malignant tumor disease.

Effect of patient-specific scapular morphology on the glenohumeral joint force and shoulder muscle force equilibrium: a study of rotator cuff tear and osteoarthritis patients.

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics.

Determination of a reference system for the three-dimensional study of the glenohumeral relationship.

OBJECTIVE: Knowledge of the normal and pathological three-dimensional glenohumeral relationship is imperative when planning and performing a total shoulder arthroplasty. There is, however, no consensus on which references should be used when studying this relationship. The purpose of the present study was to define the most suitable glenoid plane with normally distributed parameters, narrowest variability, and best reproducibility. MATERIALS AND METHODS: Three-dimensional reconstruction CT scans were performed on 152 healthy shoulders. Four glenoid planes, each determined by three surgically accessible bony reference points, were determined. Two planes were triangular, with the same base defined by the most anterior and posterior point of the glenoid. The most inferior and the most superior point of the glenoid, respectively, define the top of Saller's inferior plane and the Saller's superior plane. The two other planes are formed by best-fitting circles. The circular max plane is defined by the superior tubercle, and two points at the distal third of the glenoid. The circular inferior plane is defined by three points at the rim of the inferior quadrants of the glenoid. RESULTS: The parameters of all four planes behave normally. The humeral center of rotation is identically positioned for both the circular max and circular inferior plane (X = 91.71°/X = 91.66° p = 0.907 and Y = 90.83°/Y = 91.7° p = 0.054, respectively) and different for the Saller's inferior and Saller's superior plane (p ≤ 0.001). The circular inferior plane has the lowest variability to the coronal scapular plane (p < 0.001). CONCLUSIONS: This study provides arguments to use the circular inferior glenoid plane as preferred reference plane of the glenoid.

Arthroscopic Posterior Bone Block Procedure With Two Cortical Buttons Fixation and Specific Glenoid Guide for Posterior Shoulder Instability.

Arthroscopic posterior bone block procedure using cortical screws has been reported since 2012 for management of recurrent posterior instability associated with bone defects. To avoid screw complications, we describe a full arthroscopic technique based on cortical button fixation. With 4 portals (posterior, poster lateral, anterior, and anterolateral), we use a specific glenoid guiding system (to perform 2 tunnels) and 2 cortical buttons fixation. With a specific glenoid guide, the iliac crest bone graft (ICBG) is secured to the posterior glenoid rim by fixation with 2 cortical buttons. The ICBG is positioned protruding outside the joint through the space, and the posterior capsule is repaired while maintaining an extra-articular bone graft. The protruding bone graft increases the concavity of the glenoid with a progressive bony remodeling to improve the posterior stability of the shoulder in our clinical experience.

Serial 3D CT analysis of humeral head alignment in relation to glenoid correction and outcomes after total shoulder arthroplasty.

Background: Posterior humeral head (HH) subluxation after anatomic total shoulder arthroplasty (aTSA) is associated with worse outcomes, but it is unclear how corrective glenoid reaming correlates with HH alignment and whether HH alignment changes over time. Therefore, it was aimed to analyze the relationship between HH alignment and the scapula following aTSA to identify anatomic and surgical factors that contribute to realignment of the HH, glenoid loosening, and clinical outcomes. Methods: Three-dimensional scapulohumeral alignment was assessed on three-dimensionally reconstructed computed tomography scans of 23 patients: preoperative (T0), 2 years post-aTSA (T1), and ≥5 years post-aTSA (T2). Anterior-posterior (AP), superior-inferior (SI), and medial-lateral offset measures of the HH center to the scapula were referenced to the HH diameter (scapulohumeral subluxation index). Glenoid version and inclination were measured at T0 and T1. Central peg osteolysis, rotator cuff fatty infiltration, and vault perforation were assessed on two-dimensional computed tomography. Relative Constant Score at T2 measured clinical outcome. Results: Glenoid correction correlated strongly with AP and SI position of the HH (r = 0.733 and r = 0.797, respectively). Each degree of retroversion correction resulted in 0.9% AP scapulohumeral subluxation index offset change toward anterior. Each degree of inclination correction to superior resulted in a 1.0% offset change toward superior. A gradual postoperative proximal (mean difference [MD], -3%; P = .019), anterior (MD, 2%; P = .025), and medial (MD, 3 mm; P < .001) HH migration was observed. Asymmetric progressive rotator cuff fatty infiltration was associated with the direction of change in AP alignment over time (odds ratio, 2.04; P = .046), with progressive subscapularis fatty infiltration as the primary factor associated with gradual anterior HH translation (odds ratio, 15.61; P = .028). Gradual HH medialization was an indicator of glenoid components at risk for loosening (difference between medians, 4 mm; P = .003). Osteolysis around the central glenoid peg was influenced by overcorrection of glenoid version (MD, 7°; P = .038). Preoperative glenoid inclination was the sole anatomical or surgical factor predicting clinical outcome, as larger inferior inclination at T0 was associated with worse relative Constant Score at T2 (P = .016). Conclusion: Corrective glenoid reaming was an effective surgical technique to correct HH alignment in the AP and SI direction. Gradual anterior HH translation after aTSA was associated with progressive subscapularis fatty infiltration, and substantial HH medialization was an important indicator for potential glenoid loosening. While postoperative glenoid version and AP HH alignment were important for radiographic outcome, preoperative glenoid inclination predicted clinical outcome, as larger preoperative inferior inclination resulted in worse clinical scores.

Operative guidelines for the reconstruction of the native glenoid plane: an anatomic three-dimensional computed tomography-scan reconstruction study.

BACKGROUND: Reconstruction of the native plane in biconcave eroded glenoids is difficult. Nevertheless, accurate reconstruction of this plane is imperative for successful total shoulder arthroplasty. This study aims to determine guidelines that can increase the accuracy of glenoid component positioning. METHODS: Three different circular planes were determined on 3-dimensional computed tomography (CT) scans of 152 healthy shoulders. First, the circular max (CM) plane is formed with the superior tubercle and 2 points, 1 anterior and 1 posterior, at the rim of the inferior third of the glenoid. Second, the circular inferior (CI) plane is formed by 3 points at the inferior 2 quadrants of the glenoid rim. Third, the circular minima (Cm) plane is formed with 3 points situated at the noneroded sector of the anterior glenoid. The angulation of the spinal scapular axis (SSA), the line between the most medial point of the scapular spine and the center of the three different glenoid planes, and the correlation coefficient between the radius of the circle and the length of SSA are calculated. RESULTS: Angle SSA in the x-axis were 94°, 93°, 93° and in the y-axis were 95°, 111°, and 111° for CM, CI, and Cm, respectively. Correlation coefficient between the radius of the circle and the length of SSA: r = 0.69 for CM, r = 0.75 for CI, and r = 0.75 for Cm. CONCLUSION: Three points situated at the native anterior glenoid can reconstruct, within 2° accuracy (95% confidence interval, 1.8°-2.3°), the CI plane. A relationship exists between the radii of the 3 glenoid circles and the width of the scapula (SSA length).

Anatomical study of all carpal and adjoining bones of the wrist using 3D CT reconstruction -Finding the ultimate biomechanical theory.

BACKGROUND: The complex interplay of single wrist bones acting in combination with their ligamentous connections is still not fully understood. In this regard various theories exist, divisible in columnar and ring/row theories. The object of this study was to examine the mobility of the individual carpal bones as well as the ulna and metacarpals relative to each other in wrists of cadaveric hands using CT scans. METHODS: The regular wrist mobility of a total of 21 cadaveric hands was examined by CT imaging in neutral position, radial/ulnar abduction as well as wrist flexion and extension. The data were evaluated as 3D models by using a standardized global coordinate system and object coordinate systems. Rotation and translation of each carpal bone as well as radius/ulna and all metacarpal bones were evaluated. RESULTS: The principal motion took place in the carpus between the radius and the proximal carpal row followed by the midcarpal joint and the carpometacarpal joints and not mainly between the individual bones of a row. The scaphoid moves out of its row aggregate mainly during flexion and adapts to the motion of the distal carpal row. The trapezium and first metacarpal bones play a specific role detached from the remaining bones. CONCLUSIONS: With this study, a better understanding of the motion of the individual bones of the carpus, the metacarpals and the radius/ulna is shown. The study supports the row theory, where most motion takes place between the individual rows and not between the carpal bones, leaving the scaphoid and the first ray in a special role between the rows.