Does the position of the glenoid component shift after total shoulder arthroplasty?

 Relationship Between Glenoid Component Shift and Osteolysis After Anatomic Total Shoulder Arthroplasty Three-Dimensional Computed Tomography Analysis

These authors sought to evaluate glenoid component position and radiolucency following anatomic total shoulder arthroplasty (TSA) using sequential 3-dimensional computed tomography (3D CT) analysis in a series of 152 patients (42 Walch A1, 16 A2, 7 B1, 49 B2, 29 B3, 3 C1, 3 C2, and 3 D glenoids) undergoing anatomic TSA with a polyethylene glenoid component.

Sequential 3D CT analysis was performed preoperatively (CT1), early postoperatively (CT2), and at a minimum 2-year follow-up (CT3). 

The preoperative CT was used to characterize the "premorbid" anatomy of the shoulder, that is what it was likely to have looked like before the onset of arthritis. 

The position of the humeral head in relation to the glenoid and to the plane of the scapular body was defined. 

Central peg osteolysis was determined using the scale shown below

Glenoid component shift was defined as a change in component version or inclination of ≥ 3 degrees from CT2 to CT3. 

Glenoid component central anchor peg osteolysis (CPO) was assessed at CT3. 

Glenoid component shift occurred from CT2 to CT3 in 78 (51%) of the 152 patients. 

CPO was seen at CT3 in 19 (13%) of the 152 patients, including 15 (19%) of the 78 with component shift; increased inclination was the most common direction

Most (81%) of the patients with glenoid component shift did not develop CPO.

Walch B2 glenoids with a standard component and glenoids with higher preoperative retroversion were associated with a higher rate of shift, but not of CPO.

B3 glenoids with an augmented component and glenoids with greater preoperative joint-line medialization were associated with CPO, but not with shift. 

More glenoid component joint-line medialization from CT2 to CT3 was associated with higher rates of shift and CPO. 

A greater absolute change in glenoid component inclination from CT2 to CT3 and a combined absolute glenoid component version and inclination change from CT2 to CT3 were associated with CPO. 

Neither glenoid component shift nor CPO was associated with worse clinical outcomes.

Most of the components shifting occurred without deformation of the implant; however, a subset of 14 components demonstrated bending of the central anchor peg between CT2 and CT3 without CPO. 

CPO was associated with a higher rate of shift with larger absolute changes in glenoid component version and inclination and a greater odds of component medialization from CT2 to CT3 compared with cases without CPO, findings suggestive of early implant loosening and subsidence that raise concern about eventual implant failure.

 

Comment: This is a very thorough and interesting study. It seems that patient reported shoulder comfort and function is relatively insensitive to component shift or central peg osteolysis at a minimum of two years after arthroplasty. It also appears that in the great majority of cases using a fluted central peg, there is bone ingrowth into the central peg that persists at two years. It is interesting that the central peg can bend with component shift without loosening. Preoperative retroversion and version correction appear to be associated with an increased rate of component shifting. 

We will continue to learn from these authors which surgeon-controlled variables will optimize the long term success of shoulder arthroplasty for our patients: what is the best way to manage preoperative retroversion? what is the best way to manage preoperative joint line medialization? To answer these questions carefully controlled studies will be required to determine how much version correction is needed and, if version correction is important, how can it be best accomplished.

How you can support research in shoulder surgery Click on this link.

Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link).

How to x-ray the shoulder (see this link).

The ream and run procedure (see this link).

The total shoulder arthroplasty (see this link).

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

The smooth and move procedure for irreparable rotator cuff tears (see this link).

Shoulder rehabilitation exercises (see this link).

Total shoulder arthroplasty - humeral stem fixation and calcar resorption

Medial calcar bone resorption after anatomic total shoulder arthroplasty: does it affect outcomes?

These authors sought to determine whether humeral bone resorption was associated with inferior outcomes or higher rates of radiographic loosening in 171 TSA patients with average clinical and radiographic followup periods of 50 and 46 months, respectively.

A press-fit technique was used for humeral stem insertion in all cases. Humeral stem size was based on the first sequential broach that obtained rotational stability, typically achieving metaphyseal fixation rather than diaphyseal fixation. Morsalized bone graft from the humeral head was placed into the prepared humeral canal shortly before impaction of the final stem. The glenoid was prepared using standard noncannulated reamers, creating a concentrically matched surface for the glenoid component, often partially correcting glenoid version. The glenoid component was cemented in all cases, with pressurization of cement into the prepared glenoid surface and placement of cement behind the component prior to impaction.

Calcar resorption was identified in 110 patients (64.3%).

No significant overall differences were observed between the patient characteristics or outcomes with and without calcar resorption.

Subgroup analysis showed that patients with grade 3 resorption had a higher incidence of glenoid radiolucencies (50%, P ..001) and patients with a progression from grade 1 to grade 3 had higher incidences of glenoid (50%, P . .003) radiolucencies.

3 months post op

 88 months post op

Comment: These authors point out that other risk factors for calcar osteolysis may be more important that stress-shielding.  For example, third body wear related to polyethylene and/or cement debris contributes directly to debris-induced osteolysis. The cement technique used in this series included placement of cement onto the backside of the glenoid component. While this has been shown to improve initial glenoid fixation, the thin cement mantles that results could have led to cracks in the cement and resulting wear particles. Patients with quick progression to grade 3 were found to have significantly greater glenoid and humeral radiolucent lines. They also mention that postoperative infection may also result in both medial calcar resorption and glenoid component loosening. 

They used a impaction autograft humeral fixation technique with low filling ratios to minimize the risk of stress-shielding.  Filling ratios assessed using the initial postoperative radiographs showed metaphyseal filling ratios pf  0.43±0.1 (maximum, 0.66; minimum, 0.21) while the filling ratio at the diaphyseal region was 0.41± 0.08 (maximum, 0.59; minimum, 0.22). These are lower than many studies and consistent with those in another recently described article that showed low levels of adaptive changes with a standard length impaction grafted stem (see below).

Radiographic outcomes of impaction-grafted standard-length humeral components in total shoulder and ream-and-run arthroplasty: is stress shielding an issue?

These authors evaluated humeral stress shielding after shoulder arthroplasty performed with a smooth, standard-length humeral stem fixed with impaction autografting.

Prior to placement of the final component, cancellous autograft harvested from the humeral head was placed in the humeral canal and pressed into place using a humeral impactor with the same stem geometry as the implant. Autograft was progressively inserted until the impactor fit tightly within the humerus. The final uncoated, smooth, stemmed, fixed-angle humeral component with the desired head geometry was then driven into the prepared canal. 

At two years after surgery, the radiographic appearances were evaluated by an independent experienced shoulder surgeon from another institution not involved in the care of these patients.  The metaphysical and diaphysial filling ratios were measured as shown below.

The filling ratios were small, showing a substantial preservation of bone stock.

The overall radiographic results are shown below

The 48 ream-and-run procedures showed partial calcar osteolysis in 9 cases (19%) and the 78 TSAs showed partial calcar osteolysis in 19 cases (24%) and complete calcar osteolysis in 2 (3%).

The Simple Shoulder Test score improved from 3.9±2.5 to 9.9±2.4.

Humeral component subsidence or component shift was observed in 3 ream-and-run procedures (6%) and in 8 TSAs (10%). These radiographic findings were not significantly associated with patient demographic characteristics, canal-filling ratios, or clinical outcomes.  

The authors concluded that this independent assessment of the 2-year radiographic and clinical outcomes of a conventional smooth humeral stem inserted with impaction autografting demonstrates the clinical utility of this bone-preserving approach to humeral component fixation with minimal complications; good clinical outcomes; and low rates of bone loss, component subsidence, and shift in position.

Comment: After three decades of use, impaction autografting of a smooth standard-length stem remains our preferred method for bone-preserving humeral component fixation.

Impaction allografting remains our preferred method for addressing failed prior humeral component fixation.

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Short humeral stems - preliminary results of interest

A Short and Convertible Humeral Stem for Shoulder Arthroplasty: Preliminary Results

In their introduction, these authors point out that the humeral component is rarely the cause of the failure. However when performing a revision the humeral component may need to be removed  to allow glenoid exposure or to convert the prosthesis to a reverse total shoulder (RSA). Furthermore, "removal of a well-fixed, cemented humeral component is challenging, with high risk of complications such as intraoperative fracture." They state that "the results of the preliminary generation of this new stem have already been reported, with high rate of radiolucencies. Proximal plasma spray was secondary associated to improve metaphyseal bone fixation."

They reviewed 66 primary shoulder arthroplasties (42 anatomic total shoulders (TSA) and 24 reversed total shoulders) using a short convertible humeral stem with an average follow-up of 25.6 months (24–30.8 months).

Constant scores and range of motion improved. They reported no mechanical complication or loosening was reported. Twenty patients had proximal medial cortical bone thinning (30.3%) on the last follow-up X-rays. This occurred for 13 TSA (30.9%) and 7 RSA (29.2%). This cortical osteolysis was first seen at 1-year follow-up.  This bone resorption was only reported for women and uncemented stems. An example is shown below.

They correlated osteolysis with the 'filling ratio'.

Mean filling ratios were 0.57 for TSA and 0.62 for RSA. Bone resorption was associated with higher filling ratio than prosthesis without bone resorption.

In 8 cases, cemented stems were used, they did not find any proximal cortical bone thinning with cemented stems.

There were 7 complications (10.6%) and 2 revisions (3.0%). For the anatomical prostheses there were 3 calcar cracks, 1 hematoma, and 1 unexplained painful shoulder. For the reverse total shoulder there was 1 postoperative scapular spine fracture and 1 plexus palsy associated with excessive arm lengthening.

Seventeen of the total shoulders (40.5%) showed radiolucent lines around the glenoid component for the anatomic total shoulders.  Twelve of  these were observed on immediate postoperative X-rays, 3 were seen to be progressive. Five appeared after the immediate postoperative X-rays.  No radiolucent lines around the glenoid component were seen for the reverse total shoulders.

Comment: This candid presentation of the preliminary results with a second generation stem with proximal titanium plasma spray coating is informative. It points to the challenges of fixation when a short stem is used: cortical cracks on insertion and postoperative bone resorption, especially when the fit is tight (high filling ratio). At present it is not known how much the bone resorption will progress with time and what its consequences might be. It is also not known whether the bone ingrowth on one hand and the weakening from bone resorption on the other will create a fracture risk should the stem need to be removed at a subsequent revision.

As these authors have pointed out previously, lucent lines around the glenoid tend to progress with time.  It will be of interest to learn of the longer term radiographic and clinical survivorship of these components. 

The interested reader is invited to visit these links

Short-stemmed humeral components - do they 'preserve more bone'?

and

Humeral stems - when should I buy a convertible?

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The reader may also be interested in these posts:

Healing through joint replacement

Supporting progress in shoulder surgery

Consultation for those who live a distance away from Seattle.

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Information about shoulder exercises can be found at this link.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

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Total shoulder and hemiarthroplasty: glenoid failure, humeral osteolysis, revision surgery

Radiographic Changes Around Humeral Components in Shoulder Arthroplasty

This is an instructive review of 395 shoulder arthroplasties for primary osteoarthritis at an average follow-up of over 8 years.

The important messages are
   (1) glenoid component wear was associated with humeral osteolysis,
   (2) stress shielding was associated with press-fit humeral implants,
   (3) there was a high rate of failure of glenoid components, especially those that were metal-backed and uncemented,
   (4) the revision rate for hemiarthroplasty was lower that that for total shoulder arthroplasty.
   (5) immediate post operative radiolucent lines around the glenoid components were common

The series was actually a combination of the individual experience of five surgeons, all of which used the Aequalis shoulder system.
   one performed uncemented hemiarthroplasty (31 cases),
   one performed cemented hemiarthroplasty (16 cases),
   one performed total shoulders with uncemented stem and cemented convex back glenoid (54 cases),
   one performed cemented stems and uncemented metal backed glenoids (34 cases), and

   one performed predominantly cemented stems with flat or convex backed glenoid components (183 out of his total of 260).

With respect to the glenoid components
   (1) over 2/3 rds of the glenoids had radiolucent lines on the immediate postoperative radiographs. Comment:We have found that postoperative radiolucent lines can be eliminated by the use of a sterile C02 jet that removes debris, clot, blood, and other fluids from the bone cement interface.
   (2) 39% of the glenoid components had loosened. Comment: this represents an annual loosening rate of over 4% per year. 

   (3) tilt of the glenoid component was found in 53.5%, subsidence in 38%, and loosening without tilt or subsidence of the component in 8.5%.
  (4) Twenty-nine (36.7%) of the seventy-nine metal-backed glenoid components were loose. All of the patients with loosening of the component had complete wear of the polyethylene insert.

Osteolysis of the greater tuberosity and/or the calcar was
   (1) found in over 40% of patients with a total shoulder replacement but in none of the shoulders with hemiarthroplasty
   (2) more frequent in shoulders with glenoid loosening than in shoulders without glenoid loosening. Of the 128 shoulders with a loose glenoid component, 121 (94.5%) had osteolysis of the greater tuberosity and/or calcar. These patients had significantly lower clinical outcome scores.
   (3) more frequent in shoulders with wear of the polyethylene insert. In patients treated with a metal-backed glenoid implant (polyethylene wear was present in fifty-three (67.1%) of seventy-nine shoulders). All shoulders with wear of the glenoid insert had osteolysis of the proximal humerus.
   (4) The observation that osteolysis only occurred in total shoulder replacements, supports the hypothesis that wear particles from polyethylene are likely to be responsible for osteolysis than are cement particles.

Stress-shielding was observed only with uncemented stems and was present in almost 2/3rds of uncemented humeral stems (this was the case for both total shoulders and hemiarthroplasties). Comment: With a press fit component the load is transferred from the component to the humerus only at certain locations, usually where the distal tip of the prosthesis is wedged into the firm diaphyseal bone. This unloads the proximal humeral metaphyseal bone and leads to bone loss through stress shielding. While this effect can be prevented by the use of cement, which enables the use of a less tight fitting diaphysis, cement complicates removal of the prosthesis should revision become necessary. The use of  impaction grafting obviates the problems of cement as well as the problem of stress shielding; this has been for many years our standard approach to fixation of the humeral implant.

Revisions
   (1) 53 revision procedures (13.4%) were performed.  Comment: this represents an annualized revision rate of 1.67% per year. Eight revisions were for soft tissue problems, 14 revisions were to a reverse total shoulder because of cuff failure and glenoid loosening, 21 other revisions involved removing a loosen glenoid component. One hemiarthroplasty was converted to a total shoulder, one periprosthetic fracture was fixed, and one humeral head implant was changed.
   (2) Revisions were performed in 1 of 66 hemiatrhoplasties (1.5%). Only 16 had moderate or severe glenoid erosion. 30 of 79 shoulders with metal backed glenoids (40%). 20 of 89 shoulders with a flat-backed all-polyethylene glenoid component (22.5%). 2 of 94 shoulders with a convex-backed glenoid component (2%). Comment: it is of interest that the revision rate for hemiarthroplasty was less than that for total shoulder.

Infection
   The authors note that a recently published study found that male sex, glenoid wear, humeral loosening, and humeral osteolysis are associated with a significantly increased likelihood for a positive culture of Propionibacterium acnes in revision shoulder arthroplasty. Comment: While clinically significant humeral loosening was nearly absent in this cohort and there was no evidence for low-grade infections in these patients, the authors’ approach to culturing for Propionibacterium is not stated and it is recognized that the presence of this organism is often overlooked unless specific culturing protocols are followed. It is of interest that the findings of humeral osteolysis and glenoid wear have been shown to be strongly associated with positive cultures for Propionibacterium.

Again, this is a most informative review of shoulder arthroplasties performed by expert surgeons and followed for a substantial period of time.

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Glenoid component loosening associated with glenoid retroversion

Welcome to the 600th post on this blog.

Glenoid Component Retroversion Is Associated with Osteolysis

The authors observe that many patients with primary osteoarthritis have increased glenoid retroversion and that glenoid components inserted in retroversion may experience eccentric glenoid loading and an increased risk of component loosening. They reviewed 66 shoulders having total shoulder replacement with an all-polyethylene press-fit pegged glenoid component designed for osseous ingrowth for treatment of osteoarthritis at an average of 3.8 years. Preoperative glenoid retroversion using computed tomography scans or axillary radiographs. Preoperative CT scans were obtained when the preoperative axillary radiograph was not of sufficient quality to make an assessment of glenoid pathology in the axial plane.

The surgeon attempted to correct excessive glenoid retroversion by asymmetric reaming of the anterior part of the glenoid with the goal of achieving a component perpendicular to the plane of the scapula. When a patient had a large amount of glenoid retroversion, the surgeon accepted incomplete correction of retroversion to avoid excessive removal of bone and the resulting inability to insert a glenoid component.

They used post operative AP and axillary views to seek osteolysis around the central peg of the glenoid component. It is important to recognize, as we've pointed out before, that a standardized axillary view is sufficient as well as less costly and safer than a CT scan. The authors had previously assessed the accuracy of measurement of glenoid component retroversion on radiographs and postoperative CT scans and found a precision 95% confidence interval of 10° for version.

While the authors were blinded as much as possible, it is of note that the assessment of postoperative osteolysis and post operative retroversion were made on the same set of radiographs.

Of the fifty-three patients with study-quality preoperative axillary imaging, twenty (38%) had ≤15° of preoperative retroversion, twenty-four (45%) had >15° and ≤25°, and nine (17%) had >25° (range, 26° to 47°).

The early postoperative radiographs (made one to twelve months postoperatively) showed no osteolysis around the center peg.

At final follow-up however, 20 of the shoulders had osteolysis around the center peg as shown here

in contrast to the ideal postoperative findings shown here

This is of importance, because it suggests that with time, the quality of fixation may deteriorate.

Osteolysis around the center peg was not correlated with a worse clinical outcome defined by shoulder scores or a reoperation due to glenoid loosening over the followup period of this study.

The rate of osteolysis and the Lazarus component loosening grade were associated with (1)  the length of time after replacement, (2) preoperative glenoid retroversion, and (3) postoperative glenoid component retroversion. After adjustment for follow-up time, excessive postoperative glenoid retroversion (≥15°) was associated with an odds ratio of >5 for osteolysis.

In comparison to those with no or small amounts of osteolysis, shoulders with substantial osteolysis had higher preoperative retroversion (22.5 as compared to 14.7), higher postoperative version (15.2 as compared to 10.5), and higher degrees of postop-preop correction of retroversion (7.3 as compared to 4.2). Thus it is not clear that version correction solves the problems associated with preoperative retroversion.

As we've pointed out in previous posts, such as this one, glenoid retroversion can increase the risk of glenoid component failure through what we've described as 'rocking horse' loosening. Other factors apparently associated with glenoid component failure include the glenoid type and point of glenohumeral contact, neither of which was reported in this study.

The optimal method for managing the retroverted, B type glenoid with posterior glenohumeral contact when performing a total shoulder remains a topic of active discussion. Substantial anterior high side reaming, posterior bone grafting, and posteriorly augmented glenoid components all have been shown (see prior posts) to have their own risks.

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Glenoid component failure, osteolysis - sterilized by radiation in air

We had an interesting day yesterday in the OR. Among other revisions, smooth and moves, and ream and runs, we revised two Tornier total shoulders. The first case had already had a revision (elsewhere) of a Tornier total shoulder on the left shoulder for a failed glenoid. The right arthroplasty had been done in 2005. In 10/2012 we saw him for the first time because of pain in the right shoulder. His x-ray is shown below, revealing glenoid osteolysis.

In 5/2013 he decided to proceed with revision. At that time his films showed a dramatic increase in the osteolysis as well as evidence of a shift in the position of the glenoid component markers.

At surgery his component was loose and worn.

There was no obvious evidence of infection, but the shoulder was filled with non-inflammatory reactive tissue, such as the below.

We obtained multiple cultures for Propionibacterium and other bacteria before administering Ceftriaxone and Vancomycin (which we will continue for 6 weeks followed by a year of oral antibiotics).

After a thorough cleanout, we reconstructed his shoulder using a press fit humeral prosthesis that articulated with the rim of his residual glenoid. No glenoid bone graft was used. Post op we are starting him on our routine post-arthroplasty rehabilitation.

The second case had a Tornier total shoulder implanted in 2000. At the time of presentation to us, the radiographs, like the first case, showed massive osteolysis and glenoid component loosening.

The operative findings and the procedure were identical to the prior case. The postoperative films are shown here.

Comment: the surgical findings in these cases are consistent with either a Propionibacterium infection or with 'polyethylene disease' resulting from particles of poly released into the shoulder by component wear. Each of these glenoid components were not only loose, but the poly was degenerated suggesting that they may have been sterilized by gamma radiation in air. This is a problem previously noted in DePuy glenoids as well when the component was sterilized in air. The only way to distinguish them is by cultures of multiple samples (at least 5) of tissue and explants, holding them for three weeks and using multiple culture media.  For that reason we have both of these patients on the 'red' protocol of IV antibiotics via a PICC line for six weeks. If cultures are negative, we will discontinue antibiotics afterwards. Otherwise the patients will be on oral antibiotics for a year.

The humeral head prostheses have the largest diameter so that they will sit on the rim of the osteolytic glenoid. No glenoid bone grafting is used, but Vancomycin / allograft is used for humeral component fixation.

The histology on such cases usually looks like that shown below

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