Radiographic analysis of shoulder anatomical arthroplasty

Arthroplasty-Related Pseudotumor of the Scapula: Case Report and Review of the Literature

Arthroplasty-related pseudotumors are nonneoplastic and noninfectious inflammatory masses that are typically associated with adverse reaction to metal debris. Pseudotumors most commonly occur in the setting of metal-on-metal joint replacements at the hip. However, the presentation of pseudotumor at the shoulder is exceedingly rare. In this article, we reported a case of arthroplasty-related pseudotumor of the scapula. Clinical history, radiologic signs, and tissue analysis are described. Knowledge of this rare diagnosis will support clinical decision making for teams of radiologists, pathologists, oncologists, and orthopaedic surgeons who provide care for patients presenting with suspicious shoulder masses.

Shoulder Osteoarthritis

Glenohumeral osteoarthritis has proven to be a major contributor to shoulder joint pain and dysfunction in the elderly. There are several conditions about the shoulder that contribute to the development of glenohumeral osteoarthritis, which includes traumatic injuries, rotator cuff pathology, glenohumeral instability, glenoid dysplasia, and osteonecrosis. When glenohumeral osteoarthritis pain is refractory to conservative treatment, intra-articular injections and surgery can be performed. The radiologist should be aware of the varying types of shoulder arthroplasties, what preoperative findings influence that decision and the expected postoperative appearance of the differing components.

Biomechanical Evaluation of Recurrent Dissociation of Modular Humeral Prostheses

The purpose of the study was to evaluate the force and torque required to dissociate a humeral head from the unimplanted modular total shoulder replacement system from different manufacturers and to determine if load and torque to dissociation are reduced in the presence of bodily fluids. Impingement, taper contamination, lack of compressive forces, and interference of taper fixation by the proximal humerus have all been reported as possible causes for dissociation. Experimental values determined in this research were compared with literature estimates of dissociation force of the humeral head under various conditions to gain more understanding of the causes of recurrent dissociations of the humeral head. This study examined biomechanical properties under dry and wet conditions under clinically practiced methods. Mean load to dissociation (1513 N ± 508 N) was found to be greater than that exerted by the activities of daily living (578 N) for all implants studied. The mean torque to dissociation was (49.77 N·m ± 19.07 N·m). Analysis of R² correlation coefficients and p-values (α = 0.05) did not show any significant correlation between dry/bovine, dry/wet, or wet/bovine for load, displacement, or torsional stiffness in the majority of tests performed. Wetting the taper with water or bovine serum did not reduce the dissociation force to a statistically significant degree. Torque and lack of compressive forces at the rotator cuff may be the cause of dissociation at values less than those of activities of daily living. Torque data are provided by this study, but further research is needed to fully appreciate the role of torque in recurrent dissociations.

Magnetic Resonance Imaging Around Metal at 1.5 Tesla: Techniques From Basic to Advanced and Clinical Impact

ABSTRACT

During the last decade, metal artifact reduction in magnetic resonance imaging (MRI) has been an area of intensive research and substantial improvement. The demand for an excellent diagnostic MRI scan quality of tissues around metal implants is closely linked to the steadily increasing number of joint arthroplasty (especially knee and hip arthroplasties) and spinal stabilization procedures. Its unmatched soft tissue contrast and cross-sectional nature make MRI a valuable tool in early detection of frequently encountered postoperative complications, such as periprosthetic infection, material wear-induced synovitis, osteolysis, or damage of the soft tissues. However, metal-induced artifacts remain a constant challenge. Successful artifact reduction plays an important role in the diagnostic workup of patients with painful/dysfunctional arthroplasties and helps to improve patient outcome. The artifact severity depends both on the implant and the acquisition technique. The implant's material, in particular its magnetic susceptibility and electrical conductivity, its size, geometry, and orientation in the MRI magnet are critical. On the acquisition side, the magnetic field strength, the employed imaging pulse sequence, and several acquisition parameters can be optimized. As a rule of thumb, the choice of a 1.5-T over a 3.0-T magnet, a fast spin-echo sequence over a spin-echo or gradient-echo sequence, a high receive bandwidth, a small voxel size, and short tau inversion recovery-based fat suppression can mitigate the impact of metal artifacts on diagnostic image quality. However, successful imaging of large orthopedic implants (eg, arthroplasties) often requires further optimized artifact reduction methods, such as slice encoding for metal artifact correction or multiacquisition variable-resonance image combination. With these tools, MRI at 1.5 T is now widely considered the modality of choice for the clinical evaluation of patients with metal implants.

Radiologic Results of Three-Dimensional Templating for Total Shoulder Arthroplasty

Background

The purpose of this study was to evaluate the radiologic results of total shoulder arthroplasty using computerized three-dimensional (3D) templating in preoperative planning.

Methods

Ten patients who underwent total shoulder arthroplasty using 3D templating preoperatively were enrolled in this study. A specialized computer program was used to reconstruct the 3D images of the shoulder from the computed tomographic images. The 3D images of various sizes of prostheses were used as the template in surgical planning of the shoulder arthroplasty. The size of the glenoid, humeral head, and stem measured in 3D templating were compared with those used in actual operation. Anatomical parameters, such as humeral head size, radius of curvature, and greater tuberosity to humeral head distance of the replaced shoulder, were measured and compared with those of the contralateral normal shoulder.

Results

The agreement rates between the glenoid size, head size, head thickness, and stem size estimated preoperatively by 3D templating and those measured in operation were 100%, 100%, 100%, and 80%, respectively. The difference in humeral head size, radius of curvature, and greater tuberosity to humeral head distance between the replaced shoulder and contralateral shoulder was 1.31 mm, 0.87 mm, and 1.17 mm, respectively.

Conclusions

In total shoulder arthroplasty, 3D templating seems to enable accurate prediction of sizes of the prostheses to be inserted and thus replication of normal anatomy.

Current peri-operative imaging concepts surrounding shoulder arthroplasty

Glenohumeral osteoarthritis is a prevalent degenerative disease that can lead to excruciating pain and debility. End-stage osteoarthritis can be treated by both conservative and surgical interventions. Along with a comprehensive history and physical exam, pre-operative imaging with plain radiographs, computerized tomography, and magnetic resonance imaging plays an essential role in the decision-making process guiding whether the patient undergoes a shoulder hemiarthroplasty, anatomic total shoulder arthroplasty, or a reverse total shoulder arthroplasty. The most important pre-operative imaging factors are the integrity of the rotator cuff and presence of significant glenoid erosion. Imaging is also critical postoperatively, as signs of prosthetic loosening, rotator cuff failure (especially involving the subscapularis), periprosthetic fracture, and stress fractures are important entities to recognize. This article will review pertinent imaging findings related to the pre- and post-operative management of patients with glenohumeral osteoarthritis.

Does proximal porous coating in short-stem humeral arthroplasty reduce stress shielding?

CONTEXT

Short-stem humeral designs in shoulder arthroplasty have been introduced recently. A retrospective cohort study was conducted to determine if newer proximal porous titanium coating in humeral short stems produced clinical and radiologic improvements.

METHOD

Short-stem humeral implants (Tornier Ascend, Wright Medical) were used in 46 anatomical total shoulder replacements from October 2012 to December 2015. Clinical and radiologic measures were analyzed at one- and two-year follow-up.

RESULTS

Nineteen shoulders received earlier grit blasted stems (Ascend Monolithic), and 27 shoulders received the later stems with proximal titanium porous coating (Ascend Flex). At two-year follow-up, radiographic changes and stress shielding were similar. Medial cortical thinning were more frequently observed in Monolithic (18 of 19) compared to Flex stems (19 of 27) on the PA films, though this was not statistically significant (P = 0.061). Clinical outcome scores improved regardless of the stem type used and independent of the radiologic adaptations on plain films. One participant with the Ascend Flex developed glenoid component failure and rotator cuff tear and was subsequently revised.

DISCUSSION

Clinical and radiological outcomes are similar in both short-stem designs. Proximal titanium porous coating may reduce medial calcar cortical thinning but it does not prevent it.

KEY MESSAGE

When compared to similarly designed uncoated grit-blasted stems, proximally porous coated humeral short stems produced similar clinical and radiological results. The proximal titanium porous coating may reduce medial cortical thinning.

Imaging of Usual and Unusual Complication of Rotator Cuff Repair

Several complications may be encountered after rotator cuff (RC) repair. A thorough knowledge of surgical interventions, normal postoperative findings, and postoperative complications is crucial to provide a timely diagnosis, improving the clinical outcome of patients. Postoperative complications may involve RC, implanted device, osteochondral tissue, surgical-site infection, peripheral nerves, soft tissues, and vascular structures. In this review, we discuss the usual and unusual complications detectable after RC repair.

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.

Imaging of Shoulder Arthroplasties

OBJECTIVE

In this article, we review the preoperative imaging features used for planning shoulder arthroplasty as well as review the various shoulder arthroplasty component types, discussing the expected normal imaging features and specific complications to look for with each.

CONCLUSION

Given the increasing use of shoulder arthroplasty, it is important to understand the imaging features of the various shoulder arthroplasty complications.

Impaction autografting: bone-preserving, secure fixation of a standard humeral component

BACKGROUND

When fixed with bone ingrowth, a tight diaphyseal press fit, or cement, the humeral component of a shoulder arthroplasty may present problems of malposition, stress shielding, or periprosthetic fracture or difficulty with removal at revision arthroplasty. We have avoided the need for these fixation methods by using impaction cancellous autografting of the humeral stem, minimizing contact between the prosthetic stem and the humeral cortex. This study presents the radiographic survivorship of impaction-autografted humeral implants using component subsidence as the primary endpoint.

METHODS

We reviewed 286 primary anatomic shoulder arthroplasties having an average follow-up of 4.9 ± 2.7 years. Initial postoperative radiographs and minimum 2-year follow-up radiographs were evaluated by 3 observers to assess subsidence.

RESULTS

Two different implants (Humeral Replacement Prosthesis [HRP] and Global Advantage prosthesis) were used. Of 286 stems, 267 (93.4%) had not subsided. The Global Advantage prosthesis had a subsidence-free survival rate of 98.5% at 5 years. The stiffer-stemmed HRP used early during the study had a higher rate of subsidence compared with the currently used Global Advantage stem (hazard ratio, 5.6; P = .001). Radiolucent lines of 2 mm or greater were less common for the Global Advantage prosthesis than for the HRP in each of 7 zones (P < .001). Total shoulder arthroplasty was associated with a higher rate of subsidence compared with hemiarthroplasty (hazard ratio, 2.6; P = .12).

CONCLUSIONS

Impaction autografting provides a secure, durable, bone-preserving means of humeral component fixation in anatomic shoulder arthroplasty.

Clinics in diagnostic imaging (167). Total shoulder arthroplasty glenoid component loosening with secondary rotator cuff failure

A 59-year-old woman who had previously undergone an anatomic left total shoulder arthroplasty presented with increasing left shoulder pain and significant reduction in motion of the left shoulder joint. No evidence of prosthetic loosening or periprosthetic fracture was detected on the radiographs or fluoroscopic arthrogram images. Dual-energy computed tomography (DECT) images revealed evidence of loosening of the glenoid component and secondary rotator cuff failure. This case illustrates how a combination of detailed clinical history, careful physical examination and DECT arthrogram evaluation may be used to identify complications of an anatomic total shoulder arthroplasty.

Histological evaluation of two designs of shoulder surface replacement implants

AIMS

To assess the extent of osteointegration in two designs of shoulder resurfacing implants. Bony integration to the Copeland cylindrical central stem design and the Epoca RH conical-crown design were compared.

PATIENTS AND METHODS

Implants retrieved from six patients in each group were pair-matched. Mean time to revision surgery of Copeland implants was 37 months (standard deviation (sd) 23; 14 to 72) and Epoca RH 38 months (sd 28; 12 to 84). The mean age of patients investigated was 66 years (sd 4; 59 to 71) and 58 years (sd 17; 31 to 73) in the Copeland and Epoca RH groups respectively. None of these implants were revised for loosening.

RESULTS

Increased osteointegration was measured under the cup in the Copeland implant group with limited bone seen in direct contact with the central stem. Bone adjacent to the Epoca RH implants was more uniform.

CONCLUSION

This difference in the distribution of bone-implant contact and bone formation was attributed to the Epoca implant's conical crown, which is positioned in more dense peripheral bone. The use of a central stem may not be necessary provided there is adequate peripheral fixation within good quality humeral bone.

TAKE HOME MESSAGE

Poor osteointegration of cementless surface replacement shoulder prosthesis may be improved by implant design.

Magnetic resonance imaging of shoulder arthroplasty: review article

BACKGROUND

Magnetic resonance (MR) imaging evaluation of the painful failed shoulder arthroplasty is a useful imaging modality due to advancements in metal artifact reduction techniques, which allow assessment of the integrity of the supporting soft-tissue envelope and the implant.

QUESTIONS/PURPOSES

The focus of this pictorial review is to illustrate the benefits of MR imaging, whether used alone or as an adjunct to other imaging modalities, in aiding the clinician in the complex decision making process.

METHODS

A PubMed (MEDLINE) search focusing on the complications and imaging assessment of shoulder arthroplasty was performed. Articles were selected for review based on their pertinence to the aforementioned topics.

RESULTS

We discuss the ability of MR imaging to identify why a patient's arthroplasty may have failed. Specific causes including component loosening and implant failure, rotator cuff and deltoid integrity, infection, subtle fractures, and nerve pathology are reviewed, with illustrative sample images.

CONCLUSION

MRI is a valuable tool in the assessment for pathology in the shoulder following arthroplasty.

[Survival rate and complications of stemmed shoulder prostheses in primary osteoarthritis]

Survivorship and survival rate of shoulder prostheses can be affected by a large number of possible complications. An evaluation of the current literature and the prosthesis register, however, shows an overall low revision (1.39 revisions per 100 observation years) and loosening rates (implant-related 10-year survival rate up to 99%), comparable to that of hip and knee endoprostheses. It must be emphasized that cementless stems more often cause problems than cemented components (4.34 compared to 0.77 revisions per 100 observation years) and that secondary rotator cuff rupture (4.6%; functional deficit up to 30%) occurs more frequently than was generally assumed and is often not diagnosed or treated adequately. The infection rate amounts to approximately 1% and according to latest literature the dislocation rate is regressive and is estimated to be approximately 5%.The low complication and revision rates do not justify the replacement of stemmed prostheses by stemless implants and short stem prostheses and the preference given to the new implants is attributed more to the better revision possibilities and easier convertibility into inverse prostheses.

Shoulder arthroplasty in osteoarthritis: correlation between function and radiographic parameters

OBJECTIVES

To evaluate the correlation between radiographic parameters and functional assessments of patients with osteoarthritis of the shoulder who underwent shoulder arthroplasty and to describe the functional outcomes of this procedure in our institution.

METHODS

We evaluated 21 patients (22 shoulders) who underwent shoulder arthroplasty between 1998 and 2010 and with a minimum follow-up of 12 months. Clinical evaluation was performed using the Constant-Murley scale, UCLA, EVA and by measuring the active motion. We analysed preoperative (distance between the top of the head and the humerus and the acromion, superior migration, neck angulation, medial "offset", subluxation, glenoid erosion) and postoperative radiographic parameters (rod inclination, migration of components and loosening).

RESULTS

PATIENTS SHOWED SIGNIFICANT IMPROVEMENT IN ALL PARAMETERS: flexion (p = 0.0083), abduction (p = 0.0266), external rotation (p = 0.0062), Constant-Murley (p = 0.0001 ), UCLA (p <0.0001) and VAS (p = 0.0002). The superior migration of the humerus showed a significant correlation with UCLA and Constant-Murley scores (p = 0.0480 and p = 0.0110, respectively). The other radiographic parameters showed no correlation with the clinical outcomes.

CONCLUSION

The superior migration of the humerus is related to worse clinical scores. Level of Evidence IV, Case Series.

Current concepts of shoulder arthroplasty for radiologists: Part 1--Epidemiology, history, preoperative imaging, and hemiarthroplasty

OBJECTIVE

The purpose of this article is to provide a review of indications for shoulder arthroplasty, describe preoperative imaging assessment, present new and modified designs of shoulder arthroplasty, illustrate normal and abnormal postoperative imaging findings, and review key radiographic measurements.

CONCLUSION

Knowledge of the physiologic purpose, orthopedic trends, imaging findings, and complications is important in assessing shoulder prostheses.

Modified hemiarthroplasty for four-part fractures of the proximal humerus

BACKGROUND

Hemiarthroplasty is used to treat patients with Neer four-part fractures but the post-operative complication rate remains high, particularly with regard to shoulder joint instability. This study was aimed at evaluating the efficacy of a modified rotator cuff reconstruction and balance technique by comparing it with conventional rotator cuff restoration surgery for Neer four-part fractures.

METHODS

This retrospective therapeutic study included 67 patients with Neer four-part fractures. Forty-five patients underwent the modified surgery and 22 control patients underwent conventional surgery. All patients were followed up for more than 3 years. Outcome was assessed by grading clinical outcome and pain and strength, measuring range of motion, and radiographic analysis.

RESULTS

The Neer score was higher in the modified surgery group (84 versus 75; P = 0.009). The rate of satisfaction (Neer score ≥80) in the modified surgery group was higher than in the conventional surgery group (71.11% versus 40.91%; P = 0.017). Range of motion for active abduction, external rotation, internal rotation and active forward elevation was greater in the modified surgery group (all P < 0.01). The morbidity rate of post-operative instability of the shoulder joint in the modified surgery group was much lower than that in the conventional surgery group (2.22% versus 18.2%; P < 0.01).

CONCLUSION

The modified hemiarthroplasty procedure for treatment of Neer four-part fractures prevents post-operative instability of the shoulder joint and improves function of the shoulder more effectively than the conventional hemiarthroplasty procedure.

A quantitative method for determining medial migration of the humeral head after shoulder arthroplasty: preliminary results in assessing glenoid wear at a minimum of two years after hemiarthroplasty with concentric glenoid reaming

HYPOTHESIS

Glenoid erosion and medial migration of the humeral head prosthesis have been observed after most types of shoulder arthroplasty. A method of measuring the change in humeral head position with time after shoulder prosthetic arthroplasty was applied it to 14 shoulders that underwent humeral hemiarthroplasty with concentric glenoid reaming. We hypothesized that the measurement technique would be reproducible and that the rate of wear would be small in the series of shoulders studied.

MATERIALS AND METHODS

Standardized anteroposterior and axillary radiographs were obtained after surgery. Two examiners measured the position of the humeral head center in relation to scapular reference coordinates for the anteroposterior and axillary projections and plotted these values against time after surgery. The change in position was characterized as the slope of this plot. Shoulders were included if there were at least 3 sets of postoperative films, the last being at least 2 years after surgery.

RESULTS

The slopes measured by the 2 examiners agreed within 0.5 mm/y for the anteroposterior and the axillary projections. For the series of shoulder arthroplasties, the rate of movement of the head center toward the scapula was less than 0.4 mm/y for either examiner in either projection.

DISCUSSION

Medial migration is a concern after any type of shoulder arthroplasty, whether a hemiarthroplasty, a biological interpositional arthroplasty, or a total shoulder arthroplasty. Quantifying the rate of medial migration over time after shoulder arthroplasty is an important element of clinical follow-up.

CONCLUSIONS

This is an inexpensive, practical, and reproducible method that can be used to determine the rate of medial migration of the humeral head on plain radiographs after shoulder arthroplasty. The average rate of medial migration in the shoulders in this study was small.

Multichannel computed tomography (MCCT) analysis of glenoid erosion in shoulder hemiarthroplasty: preliminary clinical applications

Glenoid wear following shoulder hemiarthroplasty (HA) has been reported around 80% in long-term follow-up studies. Radiographic analysis is useful to depict glenoid erosion but does not evaluate accurately glenoid bone loss. Multichannel computed tomography (MCCT) allows scanning with submillimeter section thickness through dense areas of glenoid bone, despite the presence of metallic prostheses. In this preliminary study, we performed a MCCT analysis of glenoid erosion, in 15 patients with painful shoulder HA, at an average follow-up of 5.5 years. Clinical scores were retrospectively assessed at an early (1 year), medium (2.5 years), and late (5.5 years) follow-up. We analyzed the following glenoid features: articular line space (ALS), glenoid length (bone stock), glenoid version, morphology of erosion (concentric, superior ed inferior tilt), and gross bone defects. Glenoid was retroversed in 13 patients (minimum 0 degrees maximum 8 degrees), antiversed in 2 patients (2 degrees and 6 degrees). Erosion was described as concentric in 13 patients, eccentric ("superior tilt") in 1 patient, biconcave in another patient. The mean glenoid length was 19.7 mm (min 16.4 max 22.7). Gross bone defects were described in six patients. The scores registered at latest follow-up showed a significant decrease compared with the values at 1 year (P < 0.001) and at 2.5 years (P < 0.001). The patients with glenoid erosion associated with gross defects and ALS <or=1.2 mm had lower scores for pain and lower scores for ROM (P < 0.01). Multidetector CT analysis establishes a new frontier in the postoperative management of shoulder arthroplasty, and its application in the glenoid analysis offers a significant contribution for the following reasons: qualitative and quantitative glenoid features are better seen because volume-rendering eliminates most streak artifacts and produces high-quality images; spatial information relative to the prosthetic devices and the relationship among hardware and bone can be better demonstrated; allows an accurate preoperative planning prior to starting with revision surgery.

Correlation between radiographic risk for glenoid component loosening and clinical scores in shoulder arthroplasty

Glenoid component loosening is the weak point in the failure of total shoulder arthroplasty (TSA). In this study we analyse the radiographic risk factors observed on 86 cemented polyethylene glenoid components and their relationship with clinical signs at a mean follow-up of 5.8 years. Clinical assessment included Simple Shoulder Test (SST) and Constant-Murley score. Radiograms were taken to detect periprosthetic radiolucency, tilt, medial displacement and polyethylene thinning. Pearson's correlation coefficient and Spearman's rank correlation coefficient were calculated for statistical analysis. In 61 patients (71%) lucent lines were less than 2 mm wide (grade 2) and in 6 cases (7%) they were >or=2 mm wide (grade 3 and 4). Thinning of the polyethylene was found in 11 cases (13%), glenoid tilt in 6 cases (7%) and medial migration of the component in 5 cases (6%). Complete glenoid prosthetic loosening was found in 3 cases (3.5%) associated with polyethylene wear and glenoid bone loss. The Constant-Murley score associated with radiolucency grade 3 and 4 was less than 45% (38.39 +/- 8.9) (p < 0.05), while a score less than 56% (30.72 +/- 8.7) was found in patients with glenoid tilt and medial migration (p < 0.01). The mean SST score was 4.8 +/- 2.8 in case of glenoid tilt and migration of the component (p < 0.01). Removal of the glenoid component and conversion to hemiarthroplasty or reverse prostheses is suggested in painful glenoid loosening. An exhaustive analysis of radiograms is essential to detect early and late complications or risk factors of glenoid loosening.