Matthijs Jacxsens

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

ObjectiveKnowledge 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 methodsThree-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.ResultsThe 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).ConclusionsThis study provides arguments to use the circular inferior glenoid plane as preferred reference plane of the glenoid.

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.

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).

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.

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.

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

IntroductionA 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 methodsVarious 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.ResultsFrom 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.ConclusionsA 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.

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.

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 Walchs 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.

Total ankle replacement in patients with haemophilic arthropathy: primary arthroplasty and conversion of painful ankle arthrodesis to arthroplasty

There are two general surgical approaches for operative treatment of end‐stage haemophilic ankle arthropathy: ankle arthrodesis and total ankle replacement (TAR).

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.