Aims

Reverse total shoulder arthroplasty (rTSA) can be used in complex cases when the glenoid requires reconstruction. In this study, a baseplate with composite bone autograft and a central trabecular titanium peg was implanted, and its migration was assessed for two years postoperatively using radiostereometric analysis (RSA).

Knowledge of the premorbid glenoid shape and the morphological changes the bone undergoes in patients with glenohumeral arthritis can improve surgical outcomes in total and reverse shoulder arthroplasty. Several studies have previously used scapular statistical shape models (SSMs) to predict premorbid glenoid shape and evaluate glenoid erosion properties. However, current literature suggests no studies have used scapular SSMs to examine the changes in glenoid surface area in patients with glenohumeral arthritis. Therefore, the purpose of this study was to compare the glenoid articular surface area between pathologic glenoid cavities from patients with glenohumeral arthritis and their predicted premorbid shape using a scapular SSM. Furthermore, this study compared pathologic glenoid surface area with that from virtually eroded glenoid models created without influence from internal bone remodelling activity and osteophyte formation. It was hypothesized that the pathologic glenoid cavities would exhibit the greatest glenoid surface area despite the eroded nature of the glenoid and the medialization, which in a vault shape, should logically result in less surface area. Computer tomography (CT) scans from 20 patients exhibiting type A2 glenoid erosion according to the Walch classification [Walch et al., 1999] were obtained. A scapular SSM was used to predict the premorbid glenoid shape for each scapula. The scapula and humerus from each patient were automatically segmented and exported as 3D object files along with the scapular SSM from a pre-operative planning software. Each scapula and a copy of its corresponding SSM were aligned using the coracoid, lateral edge of the acromion, inferior glenoid tubercule, scapular notch, and the trigonum spinae. Points were then digitized on both the pathologic humeral and glenoid surfaces and were used in an iterative closest point (ICP) algorithm in MATLAB (MathWorks, Natick, MA, USA) to align the humerus with the glenoid surface. A Boolean subtraction was then performed between the scapular SSM and the humerus to create a virtual erosion in the scapular SSM that matched the erosion orientation of the pathologic glenoid. This led to the development of three distinct glenoid models for each patient: premorbid, pathologic, and virtually eroded (Fig. 1). The glenoid surface area from each model was then determined using 3-Matic (Materialise, Leuven, Belgium). Figure 1. (A) Premorbid glenoid model, (B) pathologic glenoid model, and (C) virtually eroded glenoid model. The average glenoid surface area for the pathologic scapular models was 70% greater compared to the premorbid glenoid models (P < 0 .001). Furthermore, the surface area of the virtual glenoid erosions was 6.4% lower on average compared to the premorbid glenoid surface area (P=0.361). The larger surface area values observed in the pathologic glenoid cavities suggests that sufficient bone remodelling exists at the periphery of the glenoid bone in patients exhibiting A2 type glenohumeral arthritis. This is further supported by the large difference in glenoid surface area between the pathologic and virtually eroded glenoid cavities as the virtually eroded models only considered humeral anatomy when creating the erosion. For any figures or tables, please contact the authors directly

Aims

We report the clinical results of glenoid osteotomy in patients with atraumatic posteroinferior instability associated with glenoid dysplasia.

Aims

Glenoid bone loss can be a challenging problem when revising a shoulder arthroplasty. Precise pre-operative planning based on plain radiographs or CT scans is essential. We have investigated a new radiological classification system to describe the degree of medialisation of the bony glenoid and that will indicate the amount of bone potentially available for supporting a glenoid component. It depends on the relationship between the most medial part of the articular surface of the glenoid with the base of the coracoid process and the spinoglenoid notch: it classifies the degree of bone loss into three types.

It also attempts to predict the type of glenoid reconstruction that may be possible (impaction bone grafting, structural grafting or simple non-augmented arthroplasty) and gives guidance about whether a pre-operative CT scan is indicated.

Common post-operative problems in shoulder arthroplasty such as glenoid loosening and joint instability can be reduced by improvements in glenoid design shape, material choice and fixation method [1]. Innovation in shoulder replacement is usually carried out by introducing incremental changes to functioning implants [2], possibly overlooking other successful design combinations. We propose an automated framework for parametric analysis of implant design in order to efficiently assess different possible glenoid configurations. Parametric variations of reference geometries of a glenoid implant were automatically generated in SolidWorks. The different implants were aligned and implanted with repeatability using Rhino. The glenoid-bone models were meshed in Abaqus, and boundary conditions and loading applied via a custom-made Python script. Finally, another MATLAB script integrated and automated the different steps, extracted and analysed the results. This study compared the influence of reference shape (keel vs. 2-pegged) and material on the von Mises stresses and tensile and compressive strains of glenoid components with bearing surface thickness and fixation feature width of 3, 4, 5 or 6 mm. A total of 96 different glenoid geometries were implanted into a bone cube (E = 300 MPa, ν = 0.3). Fixed boundary conditions were applied at the distal surface of the cube and a contact force of 1000 N was distributed between the central nodes on the bearing surface. The implants were assigned UHMWPE (E = 1 GPa, ν = 0.46), Vitamin E PE (E = 800 MPa, ν = 0.46), CFR-PEEK (E = 18 GPa, ν = 0.41) or PCU (E = 2 GPa, ν = 0.38) material properties and the bone-implant surface was tied (Figure 1). The von Mises stresses, compressive and tensile strains for the different models were extracted. The influence of design parameters in the mechanical environment of the implant could be assessed. In this particular example, the 95. th. percentile values of the tensile and compressive strains induced by modifications in reference shape could be evaluated for all the different geometries simultaneously in form of radar plots. 2-pegged geometries (green) consistently produced lower tensile and compressive strains than the keeled (blue) configurations (Figure 2). Vitamin E PE and PCU glenoids also produced lower maximum von Mises stresses values than CFR-PEEK and UHMWPE designs (Figure 3). The developed method allows for simple, direct, rapid and repeatable comparison of different design features, material choices or fixation methods by analysing how they influence the mechanical environment of the bone surrounding the implant. Such tool can provide invaluable insight in implant design optimisation by screening through multiple potential design modifications at an early design evaluation stage and highlighting the best performing combinations. Future work will introduce physiological bone geometries and loading, a wider variety of reference geometries and fixation features, and look at bone/interface strength and osteointegration predictions

The three-dimensional (3D) correction of glenoid erosion is critical to the long-term success of total shoulder replacement (TSR). In order to characterise the 3D morphology of eroded glenoid surfaces, we looked for a set of morphological parameters useful for TSR planning. We defined a scapular coordinates system based on non-eroded bony landmarks. The maximum glenoid version was measured and specified in 3D by its orientation angle. Medialisation was considered relative to the spino-glenoid notch. We analysed regular CT scans of 19 normal (N) and 86 osteoarthritic (OA) scapulae. When the maximum version of OA shoulders was higher than 10°, the orientation was not only posterior, but extended in postero-superior (35%), postero-inferior (6%) and anterior sectors (4%). The medialisation of the glenoid was higher in OA than normal shoulders. The orientation angle of maximum version appeared as a critical parameter to specify the glenoid shape in 3D. It will be very useful in planning the best position for the glenoid in TSR. Cite this article: Bone Joint J 2014;96-B:513–18

Osteoarthritis results in changes in the dimensions of the glenoid. This study aimed to assess the size and radius of curvature of arthritic glenoids. A total of 145 CT scans were analysed, performed as part of routine pre-operative assessment before total shoulder replacement in 91 women and 54 men. Only patients with primary osteoarthritis and a concentric glenoid were included in the study. The CT scans underwent three-dimensional (3D) reconstruction and were analysed using dedicated computer software. The measurements consisted of maximum superoinferior height, anteroposterior width and a best-fit sphere radius of curvature of the glenoid.

The mean height was 40.2 mm (sd 4.9), the mean width was 29 mm (sd 4.3) and the mean radius of curvature was 35.4 mm (sd 7.8). The measurements were statistically different in men and women and had a Gaussian distribution with marked variation. All measurements were greater than the known values in normal subjects.

With current shoulder replacement systems using a unique backside radius of curvature for the glenoid component, there is a risk of undertaking excessive reaming to adapt the bone to the component resulting in sacrifice of subchondral bone or under-reaming and instability of the component due to a ’rocking horse‘ phenomenon.

Cite this article: Bone Joint J 2013;95-B:1377–82.

To evaluate humeral and glenoid bone loss in patients surgically treated for shoulder instability as factors of recurrence. During the period 2000–2008, 114 patients (103 men and 11 women) with mean age of 28 yrs underwent arthroscopic treatment for shoulder instability by the same surgeon. Mean age of the 1st shoulder dislocation was 20,89 yo and the average number of dislocations per patient was 17,14. Glenoid bone loss was found in all patients (16 Large, 59 Medium, 29 Small), as well as Hill Sachs lesions (66 Large, 23 Medium, 8 Small) or both. Thirteen (13) patients had an “inverted pear” glenoid shape. Seventy five (75) were into sports and for 57 (76%) of them this involved Overhead/Contact activities. Also 20 patients presented joint hypermobility. Complete follow up existed for 92 patients and it ranged from 4–108 months (Mean=44). The recurrence of instability and the functional outcome were evaluated post-op using the Rowe Zarins Score. Recurrence of instability was noted in 5 patients (4,38%). All of them presented Hill Sachs lesions and glenoid bone loss (2 Large, 2 Medium, 1 Small) but without an “inverted pear” glenoid shape or joint hypermobility. All 5 of them were into Overhead/Contact sports activities (2 Professional: Mean=15hr/w and 3 Amateur: Mean=2,5hr/w). The post op Rowe Zarins Score ranged from 80–100 (Mean=95,11). From the evaluation of our data, it seems that humeral and glenoid bone loss do not significantly contribute to the recurrence of arthroscopically treated shoulder instability

This paper aims to evaluate the Remplissage arthroscopic technique as described by Eugene Wolf used in patients with traumatic shoulder instability that present glenoid bone loss and Hill Sachs defects. In our study 28 patients (5 women and 23 men) with mean age of 31 yrs underwent arthroscopic stabilization of the shoulder by the same surgeon during 2007–2008 period. All patients presented Hill Sachs lesion, 11 of them had medium or large glenoid bone loss, 10 had an “inverted pear” glenoid shape, 4 had been revised for stabilization in the same shoulder and 14 presented joint hypermobility. Mean age for the age of 1st dislocation was 20,1 yrs and our follow up ranged from 5–28 months (Mean=18). The recurrence of instability and the functional outcome were evaluated pre-op and postop with the Rowe Zarins Score. The post op rehabilitation was performed by a specialist. None of the patients presented recurrent instability. The Rowe Zarins Score raised from a mean pre op score of 23,33 (15–60) to a mean post op score of 97,11 (75–100) (p< 0.05). All the patients that were into sports activities before the presentation of shoulder instability began training again and our post op evaluation of the shoulder’s ROM showed a decrease in the external rotation from 0°–15°. The infraspinatus tenodesis and posterior capsulodesis in patients with humeral bone loss seems to offer so far excellent post op results despite the slight decrease in the external rotation of the shoulder

The evaluation of the results obtained after a long term follow up (over 60 months) from patients that were treated arthroscopically for shoulder instability. In our paper we evaluated 116 patients (108 men and 8 women) with mean age of 24 yo, that were treated surgically by the same surgeon from 1999–2004. Seventy seven (77) of them (66,4%) were into sports activities and during pre op clinical examination 15 patients (12,9%) were diagnosed with joint hypermobility syndrome taking into account the Beighton criteria. Arthroscopic findings showed that 80 of them (68,9%) had some kind of bone loss, either glenoid (7 Large, 23 Medium, 6 Small) or Hill Sachs lesion (28 Large, 30 Medium, 20 Small) and in 8 patients an “inverted pear” glenoid shape was found. Our follow up ranged from 60–117 months (Mean=84) and the recurrence of instability and functional outcome were evaluated post-op using the Rowe Zarins Score. Recurrent instability presented in 7 patients. Five (5) of them was due to high energy accidents, one was due to non-compliance and one was involuntary. Of these patients 5 presented Hill Sachs lesion, 3 showed glenoid bone loss (2 Large, 1 Small) and in none of them an “inverted pear” glenoid shape was found. All recurrent cases were into some kind of Overhead/Contact sports activity (6 Amateur, 1 Professional). The post op Rowe Zarins Score ranged from 80–100 (Mean=95,53). The arthroscopic treatment of glenohumeral instability is an excellent method that provides similar or better results when compared to the open surgical treatment and with clear advantages over the latter because of lower morbidity, better cosmetic effect and lower total cost

We report the long-term clinical and radiological outcomes of the Aequalis total shoulder replacement with a cemented all-polyethylene flat-back keeled glenoid component implanted for primary osteoarthritis between 1991 and 2003 in nine European centres. A total of 226 shoulders in 210 patients were retrospectively reviewed at a mean of 122.7 months (61 to 219) or at revision. Clinical outcome was assessed using the Constant score, patient satisfaction score and range of movement. Kaplan-Meier survivorship analysis was performed with glenoid revision for loosening and radiological glenoid loosening (sd) as endpoints. The Constant score was found to improve from a mean of 26.8 (sd 10.3) pre-operatively to 57.6 (sd 20.0) post-operatively (p < 0.001). Active forward flexion improved from a mean of 85.3° (sd 27.4) pre-operatively to 125° (sd 37.3) postoperatively (p < 0.001). External rotation improved from a mean of 7° (sd 6.5) pre-operatively to 30.3° (sd 21.8°) post-operatively (p < 0.001). Survivorship with revision of the glenoid component as the endpoint was 99.1% at five years, 94.5% at ten years and 79.4% at 15 years. Survivorship with radiological loosening as the endpoint was 99.1% at five years, 80.3% at ten years and 33.6% at 15 years.

Younger patient age and the curettage technique for glenoid preparation correlated with loosening. The rate of glenoid revision and radiological loosening increased with duration of follow-up, but not until a follow-up of five years. Therefore, we recommend that future studies reporting radiological outcomes of new glenoid designs should report follow-up of at least five to ten years.