Wednesday, March 22, 2017

Patient outcomes - what's the score?

Clinical outcomes of arthroscopic rotator cuff repair: correlation between the University of California, Los Angeles and American Shoulder and Elbow Surgeons scores

These authors performed a retrospective study of 143 patients who underwent arthroscopic rotator cuff repair using the University of California, Los Angeles (UCLA) and American Shoulder and Elbow Surgeons (ASES) scores preoperatively and at 6, 12, and 24 months after surgery. They found that the UCLAand ASES scores showed a very high correlation (r = 0.91). In all the postoperative clinical evaluations, the scores obtained from the 2 scales were highly or very highly correlated (r = 0.87-0.92, P < .001). For the preoperative scores, the correlation was moderate (r = 0.67, P < .001).

Comment: Documenting the effectiveness of treatment is of great importance to shoulders surgeons and their patients.  Recently, authors have pointed to the observer dependence of scales that include measurements of strength and range of motion, such as the Constant and UCLA scores. Theses scales also have the disadvantage of requiring return of patients for an in-person examination, resulting in attrition of those available for followup. In contrast, scales such as the modified ASES, SANE and Simple Shoulder Test (SST) are purely patient reported metrics with the advantages of absence of observer dependence and the ability to complete the assessment without return to the office. The convenience of these forms puts outcome assessment within reach of all shoulder surgeons, so that they can learn the effectiveness of their treatments of their own patients.

As for the choice among the different patient reported measures, each has its own characteristics of convenience, brevity, and assessment of different aspects of shoulder comfort and function. Some, such as the SANE, boil everything down to one number, loosing the ability to assess different components of the shoulder's status. Others, such as the ASES score, require the patient to choose among "unable to do", very difficult to do", "somewhat difficult" and "not difficult" for each shoulder function. Still others, such as the Simple Shoulder Test, provide "yes" or "no" questions regarding twelve common activities of daily living.

In that surgeons from multiple countries desire to compare outcomes, having the scale validated in different languages can be helpful.

The authors of this paper are from São Paulo, Brazil; so it would be of interest to know how generally applicable the UCLA and ASES scores were to their Portuguese-speaking patients.

Of possible interest to them is this link.
Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

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See from which cities our patients come.

See the countries from which our readers come on this post.

Thursday, March 16, 2017

Shoulder Fellowship: the future of our specialty.

The American Shoulder and Elbow Surgeons, our national organization, is concluding this year's matching system by which the 58 young orthopaedic surgeons wishing advanced training in shoulder and elbow surgery will be paired with the 27 programs offering 42 fellowship positions. As can be seen from these numbers, there is strong competition for the available fellowships.

At the University of Washington we offer two fellowship positions each year and have just concluded our interviews with 21 of the most competitive candidates for our program. Those paired with us by the fellowship matching program will become the 49th and 50th University of Washington Shoulder Fellows. These surgeons will spend a year with us learning, teaching, caring for patients, discovering new knowledge and enjoying the beautiful Pacific Northwest (see this link).

Our fellowship was started 30 years ago and has produced truly outstanding shoulder surgeons who have now established robust practices both near and far, including Vancouver, New Hampshire, Miami, and San Diego. They have made and continue to make meaningful contributions to the evaluate and management of individuals troubled with shoulder and elbow problems. Half of our graduates have earned admission to the prestigious American Shoulder and Elbow Surgeons society. One of our alumni, Tony Romeo, is the current president. Here are a few of our older fellows, perhaps you recognize some of them.

From left to right, Steve Lippitt, John Sidles, Mark Lazarus, Kevin Smith, David Duckworth, the late Doug Harryman, Michael Pearl, Rick Matsen, Dean Ziegler, Craig Arntz, and Tony Romeo.

We are most grateful to the alumni of our fellowship for their research - which includes many foundational contributions to the literature, for their help in the care of our patients, and for their ongoing work to make tomorrow's patient care better than yesterday's.

We invite you to learn more about our fellowship by visiting this link.

Thursday, March 9, 2017

Instability after shoulder arthroplasty - an issue of surgical technique

The main cause of instability after unconstrained shoulder prosthesis is soft tissue deficiency

These authors reviewed 532 patients having shoulder arthroplasties and found 27 who experienced instability after surgery, for an overall incidence of 5.07%

They found 10 isolated subscapularis tears, 6 massive rotator cuff tears, 8 component malpositions, 2 component dissociations or loosening, and 1 humeral shortening. Half of the instability cases had type B or C glenoid or an anterior glenoid defect. Dislocations occurred early (within the first 6 months) in 20 patients and later in 7.

The authors provided data on each patient:

AGBL, anterior glenoid bone loss;  hemi, hemiprosthesis; LAD, locked anterior dislocation;  OA, (primary) osteoarthritis;  PL, post-Latarjet; PTOA, post-traumatic osteoarthritis; RCT, rotator cuff tear; SScp, subscapularis; PE, polyethylene; TSACG, total shoulder arthroplasty cemented glenoid component; TSAMB, total shoulder arthroplasty metal-backed component.

Comment: This paper is interesting for several reasons: 
(1) one in twenty arthroplasties were complicated by instability
(2) ten of the cases of instability were associated with subscapularis failure - indicating the need for great care in the subscapularis repair and protection until the repair heals
(3) six of the cases were associated with massive cuff tears - most of which occurred at or after two years, suggesting the need to inform patients of this risk and advising them to avoid heavy use of the reconstructed shoulder
(4) nine of the cases were associated with prosthesis malposition - indicating the importance of surgical technique
(5) two of the cases were associated with glenoid component loosening or dissociation - again suggesting the importance of prosthesis selection and surgical technique.

These are educational points: most of the factors associated with instability appear to be addressable by better surgical technique and careful rehabilitation after surgery.

Tuesday, March 7, 2017

Propionibacterium - follow the money!

Microbiota bacteriana asociada al papel moneda de circulación en Colombia

Commonly used objects such as currency paper can be colonised by bacteria and can serve as carriers of microbes. This colonisation might expose us to unnoticed pathogenic bacteria. In this study, the researchers obtained a detailed panorama of the microbes that can be carried on currency notes in Colombia by using 454 next-generation deep sequencing of 16S amplicón libraries. A total of 233 bacterial genera were detected and classified, 12 of which are potential human pathogens. The most abundant genera were Propionibacterium, Streptococcus, Staphylococcus and Pseudomonas. To date, this is the first in-depth analysis of the microbiota carried by circulating banknotes in our continent and it offers insights into daily exposure to microbes when using banknotes in Colombia.

The same must hold true for the currencies of all countries.

For the historical reference to 'follow the money' see this link.

Comment: This important study complements other evidence that Propionibacterium, including drug resistant strains, can be easily passed from one person to another. See: Propionibacterium acnes and bacterial resistance

In this review article, the authors point out that Propionibacterium acnes is one of the main microorganisms found on the skin. It is predominantly found in hair follicles, prefers anaerobic conditions, preferably colonizes the areas with high sebum production, and is the main bacterium involved in the pathogenesis of acne. They suggest that the indiscriminate use of antibiotics for the treatment of acne vulgaris can result in the development of bacterial resistance.

Several observations in this article are of interest to us shoulder surgeons:

There are over one million Propionibacterium per square centimeter of skin.

Propionibacterium inhibits the invasion of the skin by common pathogens such as Staphylococcus aureus and Streptococcus pyogenes.  Its hydrolyzation of triglycerides with the release of free fatty acids (including propionic acid) contributes to the acid pH of the skin’s surface, which is another factor for skin protection. Note: this suggests that elimination of Propionibacterium from the skin of the surgical site may open the door for worse bugs.

There are many different types of Propionibacterium; on average, each individual has 3 different Propi ribotypes on the skin each with different pathogen potential and different resistance patterns. 

Persons can transmit the different clones to other individuals, and thus resistant bacteria can be spread throughout the population by 'rubbing elbows'.

There has been an increasing number of cases of antibiotic- resistance by P. acnes over the years: in the UK, the resistance rate increased from 34.5% in 1991 to 55.5% in 2000;156 94% of  the isolates in Spain and 51% from the isolates in Hungary were  resistant to at least one antibiotic. The highest resistance rates are related to erythromycin, with cross-resistance to clindamycin. 

Resistance comes from gene mutation:

In cases of severe infections caused by P. acnes, surgical procedures should be combined with crystalline penicillin, vancomycin, daptomycin, and rifampicin due to their effect on the biofilm.

The reasons for the emergence of Propionibacterium as a problem in shoulder surgery is becoming clearer - the use of antibiotics for acne and for other reasons is changing the genetics of the bacterium to favor antibiotic resistance and the resistant strains are being exchanged within the human population.


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Monday, March 6, 2017

How should the subscapularis be managed in total shoulder arthroplasty?

Lift-off Test Results After Lesser Tuberosity Osteotomy Versus Subscapularis Peel in Primary Total Shoulder Arthroplasty

These authors conducted a retrospective cohort study of 90 primary anatomic total shoulder (TSA) procedures performed with either a subscapularis peel (SP) or a lesser tuberosity osteotomy (LTO) from 2002 to 2010. Procedures performed after 2007 had a LTO (44) whereas those before 2007 had a SP (46).

The authors used the 'lift off test' as their primary outcome measure, recognizing that while this assessment can be a highly specific and sensitive test of subscapularis function, "it is difficult to perform correctly."

Their lift-off test results plotted against the ordinal sequence of patients. Abnormal results are noted with a vertical line. Procedures 1 to 46 were performed with subscapularis peel. Procedures 47 to 90 were performed with lesser tuberosity osteotomy.

The results of their multivariate analysis is shown below, showing that in their patients, workers' compensation insurance, subscapularis peel, and smoking had the highest odds ratios of an abnormal lift off test.

The authors point out the limitations of this study:  different surgical techniques were employed between the two groups, different implants were used in the two groups, the two groups of procedures were not performed during the same time period, and the followup interval was twice as long for the SP group (5.6 vs 2.7 years).

They include a summary of some of the prior articles on the subject:

Comment: We avoid lesser tuberosity osteotomy because it can compromise the fixation of the humeral component in the metaphysis and obligates sacrifice of the long head tendon of the biceps (we are not routine 'biceps killers').

Our surgical approach involves a careful peel of the subscapularis tendon from the lesser tuberosity with attention to preserving the integrity of the biceps tendon and a 360 degree release of the capsule from the glenoid to resolve limitation of external rotation. By retaining the capsule on the deep surface of the tendon, the strength of the repair is enhanced.

At the conclusion of the case, drill holes are placed through good bone at the margin of the neck cut and six sutures of #2 non-absorbable suture are passed through these holes.

 These sutures are then passed through the tendon edge and tied securely.

A principal cause of post operative subscapularis failure is the overzealous and premature stretching of external rotation or premature initiation of internal rotation strengthening as explained in this post:
Rehabilitation after shoulder arthroplasty - cautions!

Our approach is to limit external rotation stretching to zero degrees (the hand shake position) and avoid internal rotation strengthening exercises for at least 3 months after surgery. We also caution patients about the risk of events that may suddenly externally rotate the shoulder such as a fall or a sudden pull on the arm from a leashed dog.

Other related posts are listed below:

Subscapularis failure after arthroplasty - evaluation and management

The biomechanics of subscapularis repair - all sutures are not equal!

Subscapularis in shoulder arthroplasty

Shoulder joint replacement arthroplasty - spare the subscapularis, spoil the arthroplasty?

How well does the subscapularis work after total shoulder arthroplasty? ?Hazards of inter scalene block?

Failure of lesser tuberosity osteotomy in total shoulder joint replacement - a cautionary tale

Reverse total shoulder - is an eccentric glenosphere of value?

These authors compared the clinical and radiological results of Reverse Shoulder Arthroplasty (RSA) using an eccentric glenosphere (SMR Reverse Shoulder Prosthesis) (11 patients) to those using a concentric glenosphere (9). All glenoid components were placed with 15°of inferior tilt.

There was no statistically significant difference between the two groups in clinical outcome.

9 patients with concentric glenospheres developed notching

 compared with 2 of 11 patients with eccentric glenospheres (p = 0.022).

Comment: While in the past scapular notching has been dismissed as a finding without clinical importance, more recent publications point to its association with inferior clinical outcomes. See this link.

While this report focuses on the concentricity / eccentricity of the glenosphere, it seems that the lateral offset of the glenosphere, the placement of the glenosphere on the scapula, adequate resection of potentially contacting bone, and the humeral component design are at least as important in avoiding unwanted contact between the humeral component and the scapula as described here:

Contact mechanics of reverse total shoulder arthroplasty during abduction: the effect of neck-shaft angle, humeral cup depth, and glenosphere diameter.

These authors created finite element reverse shoulder arthroplasty (RSA) models with varying neck-shaft angles (155°, 145°, 135°), sizes (38 mm, 42 mm), and cup depths (deep, normal, shallow) were loaded with 400 N at physiological abduction angles.

They found that the location of maximum contact stress were typically located inferomedially in the polyethylene humeral cup. 

Reducing the neck-shaft angle reduced the contact area and increased maximum contact stress. 

Increasing the glenosphere size increased the contact area and slightly decreased maximum contact stress. 

Decreasing the cup depth reduced the contact area  and increased maximum contact stress.

Note the tradeoff: although reducing the neck-shaft angle and cup depth can improve range of motion these changes may have negative effects on contact mechanics.

It is of interest that current practice of RSA is tending toward implant modifications that increase range of motion: reduced neck shaft angle, smaller glenosphere diameter and shallower cups, all changes that may increase the risk of cup wear.

Thus in reverse total shoulder arthroplasty, design does matter. As we pointed out in a recent post and here,  different component designs have different effects on the position of the center of rotation - both superiorinferiorly (which affects deltoid tension) and mediolaterally (which affects stability and the proximity of the medial aspect of the humeral component to the glenoid).  The design of the component also determines the shape of the glenoid polyethylene and the varus/valgus orientation of the humeral cup. Stated simply, designs that place more polyethylene beneath the glenosphere tend to be more stable on one hand while increasing the risk of notching on the other.

Contact between the polyethylene at the medial aspect of the humeral cup and the scapula is bad; it can give rise to (1) scapula notching, (2) instability from levering of the humeral component away from the glenoid, (3) limited range of motion and (4) destruction of the polyethylene as shown below and as described here and here with the production of polyethylene debris.

Consider the figures below, each of which was taken from the website of a vendor of a reverse total shoulder (please recall that we have no financial relationships with any company making orthopaedic implants). Note the relationship of the center of rotation of the glenoid component to the proximity of the medial aspect of the humeral cup to the scapula. Interestingly some illustrations show the arm in abduction, which can mask the proximity when the arm is adducted. 

Some authors have advocated modifying the medial/lateral position of the glenosphere by the insertion of a bone graft with the explicit goal of minimizing the risk of notching as shown below.
Some prosthetic designs accomplish the same effect by adding a neck to the glenosphere.
This change in design has an effect on the medial/lateral position of the center of rotation and adding distance between the humeral component and the scapula.

It is important to keep an eye on the mechanisms of reverse total shoulder failure as posted here and here and here and here

Our current approach to reverse total shoulder arthroplasty is shown in this post

Finally, when considering a given prosthesis design, it is important to consider its overall track record. Here is a chart from the Australian Orthopaedic Association National Joint Replacement Registry Annual Report 2015 - Shoulder Arthroplasty suggesting a higher revision rate for the prosthesis used in this study

Similar results with longer followup were reported in the 2016 report (see this link).


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Saturday, March 4, 2017

The dislocated reverse total shoulder

Treatment and Outcomes of Reverse Shoulder Arthroplasty Dislocations

These authors reviewed their experience with nonoperative and operative management of dislocated  primary and revision reverse total shoulders (RSAs).

They reported that between 2006 and 2013, dislocation occurred in 12/1081 primary RSAs (1.1%) and 15/342 revision RSAs (4.4%).

Seventeen (69%) shoulders dislocated within 3 months of surgery.

After dislocation of a primary RSA, closed reduction was successful in 3 of 5 cases, while revision surgery was successful in 7 of 8 cases. 
After dislocation of a revision RSA, closed reduction was successful in 1 of 5 cases, while revision surgery was successful in 7 of 11 cases. 

Overall, 9 shoulders (33%) had persistent instability at the final follow-up: 2/12 (17%) primaries versus 7/15 (47%) revisions. Preoperative prosthetic instability was the main risk factor for chronic instability in the revision cohort . Worse functional outcomes were associated with the dislocation of a revision RSA and with female sex.

The case presented is instructional (see figures below the text):

An 80-year-old female who underwent primary RSA for rotator cuff arthropathy that sustained an anterior dislocation (a) of the prosthesis 1 year after surgery. The patient was initially managed with closed reduction but had continued instability events. She was then treated with upsizing of the polyethylene component during a modular exchange. (b) An intraoperative photograph of the polyethylene insert showing damage to the anterior lip from chronic instability events. Her shoulder remains stable at 2 years after revision (c).

Comment: A common cause of instability is unwanted contact between the humeral cup and th ebone of the scapula, as is suggested by figure (b) above. An alternate explanation for the polyethylene damage, as the authors suggest, is the trauma to the polyethylene that occurs with dislocation and reduction. Progressive damage to the rim of the humeral cup facilitates subsequent dislocations.

The take away lessons include: 
(1) Before closing a reverse total shoulder procedure, examine the shoulder for unwanted contact, excessive laxity and for instability in all positions of the shoulder and resolve these issues before closure.
(2) In performing a reverse total shoulder for failed prior arthroplasty, recognize that instability is a major cause of complications - in these cases six weeks of postoperative immobilization may be helpful.
(3) Before and after surgery plan to minimize risk of falls, extreme positions, and unwanted loading.

More on this challenging problem can be found in this recent paper and below.
Dislocation following reverse total shoulder arthroplasty

These authors reviewed 22 patients having operative revision of a reverse total shoulder ( RTSA )  because of instability.

Follow-up was obtained on 19 patients at 4.9 ± 2.5 years.
14 had early and 5 had late dislocations. 

Most patients were men, were aged over 70 years, and had a history of prior shoulder surgery. 

The authors believed that 13 had inadequate soft-tissue tensioning (2  due to partial axillary nerve injuries). The remaining patients had asymmetric liner wear, mechanical liner failure, or impinging heterotopic ossification.

Of the five late dislocations, 3 had asymmetric liner wear and 4 had evidence of unwanted contact between the humeral cup and the scapula.

Recurrent instability after revision was present in 4 of the 14 early and 2 of the 5 late dislocators. 

Comment: While reverse total shoulder arthroplasty is often performed for glenohumeral instability, post-reverse total shoulder dislocation is one of the most important complications of this procedure. One of the interesting concepts is the role of unwanted contact between the medial humeral component and the lateral scapula as discussed here:

Impact of scapular notching on clinical outcomes after reverse total shoulder arthroplasty: an analysis of 476 shoulders

These authors reviewed 476 shoulders at a minimum of 2 years after reverse total shoulder arthroplasty.

Scapular notching was observed in 10.1% (48 of 476) of rTSAs and was associated with a longer clinical follow-up, lower body weight, lower body mass index, and when the operative side was the non-dominant extremity. 

Patients with scapular notching had significantly lower postoperative scores on the Shoulder Pain and Disability Index, Constant, Simple Shoulder Test, and University of California, Los Angeles, Shoulder Rating Scale compared with patients without scapular notching. 

Patients with scapular notching also had significantly lower active abduction and significantly less strength

Patients with scapular notching had a significantly higher complication rate.

This is a welcome study, because scapular notching after a reverse total shoulder has often been written of has having 'no clinical consequence'.

The concern is not so much about the loss of bone at the scapular neck

but rather the concern is what's causing the bone erosion.

In most cases, scapular notching is caused by unwanted contact between the polyethylene of the humeral cup and the bone of the scapula. While the effect on the scapular bone is evident on radiographs, the effect on the humeral polyethylene is only seen at the time of revision surgery.

Particles of polyethylene wear are known to cause inflammation, pain, stiffness and loosening.

A number of strategies can be used to avoid unwanted contract between the humeral polyethylene cup and the scapula. One is to use a glenoid component with lateral offset as shown on the right below.

Our technique reverse total shoulder arthroplasty is shown here:  Reverse total shoulder technique

Here is the x-ray of a lady with a failed prosthesis for fracture. Note the superior displacement of the humeral head, the long cemented stem and the poor quality of the glenoid bone.

Her surgeon converted her to a reverse total shoulder with bone graft around the humeral component and a Grammont-style prosthesis

At two years after surgery, she had increasing shoulder pain and these films showing bone loss at the inferior aspect of her glenoid along with some evidence of contact between the lower screw and the humeral component.

Her most recent films show progressive loss of the bone supporting the glenoid component.

While this patient has yet to undergo a revision, we suspect that her humeral component may look like this.

This is a good time to review the article:

Anytime we have unintended contact between high density polyethylene and bone, it is a problem. Scapular notching is a radiographic finding, but the real concerns are about (1) the damage to the poly of the humeral cup, (2) loss of the bone of the scapula that supports the glenoid component, and (3) the potential for instability resulting from leverage of one against the other. See this previous post which discusses this phenomenon in some detail.

In the Grammont-type reverse total shoulder, contact of the adducted humeral component against the scapula is not uncommon as shown in these figures from a manufacturer's website (arrow inserted by us to show point of contact when the arm is brought to the side).

These authors retrospectively reviewed 448 patients who underwent a Grammont-type reverse total shoulder  (461 shoulders) performed for rotator cuff tear arthropathy or osteoarthritis with cuff deficiency with a mean followup of 51 months (range, 24-206 months). They found notching of the scapula in 68% of the cases; it was present in 48% at one year after surgery. 

Notching was more common in active patients, in patients with cuff tear arthropathy, and in patients with greater degrees of superior displacement of the humeral head before surgery. Strength and range of motion were compromised in patients with notching.

Importantly, 36% of shoulders with notching had humeral radiolucent lines (in contrast to 17% in those without notching), suggesting the possibility that polyethylene particles from the humeral cup causing bone resorption. Similarly glenoid loosening was three times more common in the presence of notching.

The authors point out that standardized plain x-rays are necessary for the evaluation of notching, noting that sometimes notching is better seen on the axillary view.

Scapular notching is important and can be expected to adversely affect the long term durability and function of the reverse. It is best avoided by (1) use of a glenoid component design that offsets the center of rotation from the scapula, (2) proper positioning of the glenoid component at the inferior aspect of the glenoid, (3) avoiding superior tilt of the glenoid component, and carefully checking for contact between the humeral component and scapula at surgery when the arm is adducted and rotated (see below).


To see the topics covered in this Blog, click here

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 runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'