Saturday, February 24, 2018

Propionibacterium - resistance to clindamycin

Propionibacterium acnes Susceptibility and Correlation with Hemolytic Phenotype

These authors tested the antibiotic susceptibility and hemolytic activity of 106 P. acnes strains from sterile body sites (i.e. not from infections) collected at their medical center.
14 were hemolytic and 83 were not.
 

 They found that 9% of the strains were resistant to clindamycin and that there was an association between those phenotypes that were hemolytic on Brucella Blood Agar and clindamycin resistance.







Comment: This study again points out that all Propionibacterium are not the same. Some strains are hemolytic and some are clindamycin resistant. In shoulder arthroplasty prophylaxis and in the treatment of shoulder arthroplasty infections, antibiotics other than clindamycin may be preferable.

This article should be contrasted with

Hemolytic strains of Propionibacterium acnes do not demonstrate greater pathogenicity in periprosthetic shoulder infections

in which patients with at least 1 positive culture growth for P acnes at the time of revision surgery were identified with P acnes isolates available for hemolysis testing. Patients were grouped into
those with P acnes isolates positive (n = 20) and negative (n = 19) for hemolysis. The groups were retrospectively compared based on objective perioperative findings around the time of revision surgery and the postoperative clinical course, including the need for revision surgery. All cases were classified into categories of infection (definite infection, probable infection, and probable contaminant) based on objective perioperative criteria.

In this study the presence of hemolysis was not significantly associated with an increased likelihood of infection (P = .968). Hemolysis demonstrated a 75% sensitivity and 26% specificity for determining infection (definite infection and probable infection categories). The hemolytic and nonhemolytic groups showed no difference regarding preoperative serum erythrocyte sedimentation rate and/or C-reactive protein level (P = .70), number of positive cultures (P = .395), time to positive culture (P = .302), and presence of positive frozen section findings (P = .501). Postoperatively, clindamycin resistance, shoulder function, and the rate of reoperation were not significantly different between the hemolytic and nonhemolytic groups.

These authors concluded that presence of hemolysis was not associated with increased pathogenicity in patients with P acnes–positive cultures following revision shoulder arthroplasty, when assessed by objective perioperative criteria and the postoperative clinical course.

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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

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

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Friday, February 23, 2018

How can we keep orthopaedic care from becoming unaffordable?

Strategies to Contain Cost Associated with Orthopaedic Care

These authors point out that orthopaedic surgeons are responsible for a large and rapidly growing portion of the total healthcare spending in the United States. They describe some cost-containment strategies, including collaboration with vendors, value analysis teams, operating room efficiency, bundled payments, and gainsharing. They also point to barriers to cost reduction: the lack of transparency in implant pricing (because of non-disclosure clauses in the deals companies make with hospitals) and surgeons clinging to more expensive personal preferences.


Comment: In two years, U.S. Healthcare costs are predicted to reach 20% of the value of all U.S. goods and services, the GDP.




Health care costs per person growing almost 50% faster than per person income, a trend that is clearly not sustainable.


A substantial portion of this growth in national health care expenditure is related to the treatment of patients with musculoskeletal problems. Some of the drivers of increase cost are unavoidable: the need for total hip arthroplasty in patients aged 45 to 54 is expected to increase 6 times from 2006 to 2030, while the need for total knee arthroplasty in patients aged 45 to 54 is expected to increase 17 times over this period. 

There are some important ways that each surgeon can contribute to lowering the cost of orthopaedic care that were not mentioned in this article:
(1) avoiding expensive imaging that does not change the treatment of the patient (e.g. no need for a CT scan in most patients with shoulder arthritis)
(2) avoiding elective surgery in patients who do not have adequate medical, mental and social health
(3) avoiding procedures of unproven value (e.g. balloon "spacers" for irreparable cuff tears)
(4) avoiding unnecessary application of technology (e.g. patient specific instrumentation for most cases of shoulder arthroplasty)
(5) avoiding implants with higher than average failure rates (e.g. metal backed glenoid components)
(6) being aware of the effect of financial conflicts of interest on presentations and publications
(7) exercising the best possible care of patients before, during and after surgery to avoid the expenses of complications and malpractice litigation.

If we are thoughtful in the way we spend money in the care of our patients today, we will go a long way to assuring that adequate resources will be there to care for our patients in the future.
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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

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

See from which cities our patients come.

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Monday, February 19, 2018

Promises to keep

Stopping by Woods on a Snowy Evening

Whose woods these are I think I know.   
His house is in the village though;   
He will not see me stopping here   
To watch his woods fill up with snow.   

My little horse must think it queer   
To stop without a farmhouse near   
Between the woods and frozen lake   
The darkest evening of the year.   

He gives his harness bells a shake   
To ask if there is some mistake.   
The only other sound’s the sweep   
Of easy wind and downy flake.   

The woods are lovely, dark and deep,   
But I have promises to keep,   
And miles to go before I sleep,   
And miles to go before I sleep.




Saturday, February 17, 2018

Surgically prepared skin is not sterile

Preoperative Skin-Surface Cultures Can Help to Predict the Presence of Propionibacterium in Shoulder Arthroplasty Wounds

These authors point out that propionibacterium species are commonly cultured from specimens harvested at the time of revision shoulder arthroplasty. These bacteria reside in normal sebaceous glands, out of reach of surgical skin preparation. The arthroplasty incision transects these structures, which allows Propionibacterium to inoculate the wound and to potentially lead to the formation of a biofilm on the inserted implant.

To help identify patients who are at increased risk for wound inoculation, they investigated whether preoperative cultures of the specimens from the unprepared skin surface were predictive of the results of intraoperative cultures of dermal wound-edge specimens obtained immediately after incision of he surgically prepared skin.

Sixty-six patients (mean age, 66.1 ± 9.4 years [range, 37 to 82 years]; 73% male) undergoing primary shoulder arthroplasty had preoperative cultures of the unprepared skin surface and intraoperative cultures of the freshly incised dermis using special culture swabs.

For the first 50 patients, a control swab was opened to air during the same time that the dermal specimen was obtained.

The results for female and male patients were characterized as the Specimen Propionibacterium Value (SpPV) (see this link). Here are some examples of the semiquantitative laboratory reports they used in the SpPV determination.





They then determined the degree to which the results of cultures of the skin surface specimens were predictive of the results of culture of the dermal specimens.

The skin-surface SpPV was ≥ 1 in 3 (17%) of the 18 female patients and 34 (71%) of the 48 male patients (p <0.001). The dermal SpPV was  ≥ 1 in 0 (0%) of the 18 female patients and 19 (40%) of the 48 male patients (p < 0.001).

None of the control samples had an SpPV of  ≥ 1  The predictive characteristics of a skin-surface SpPV of  ≥ 1 for a dermal SpPV of  ≥ 1 were as follows: sensitivity, 1.00 (95% confidence interval [CI], 0.82 to 1.00); specificity, 0.62 (95% CI, 0.46 to 0.75); positive predictive value, 0.51 (95% CI, 0.34 to 0.68); and negative predictive value, 1.00 (95% CI, 0.88 to 1.00).

A preoperative culture of the unprepared skin surface can help to predict whether the freshly incised dermal edge is likely to be positive for Propionibacterium. This test may help to identify patients who may merit more aggressive topical and systemic antibiotic prophylaxis.

This study shows that surgeons have the opportunity to use preoperative skin cultures to determine the likelihood that the shoulder arthroplasty wound will be culture-positive for Propionibacterium.

Comment: This study is important for at least four reasons: (1) when the skin is incised for a shoulder arthroplasty, the freshly cut dermal edge is often culture positive for Propionibacterium in spite of IV antibiotics and surgical skin preparation, (2) it is important that each surgeon know his/her rate of positive control cultures to better inform the interpretation of deep wound cultures, (3) the semiquantitative results of cultures appear to be more useful than simply reporting a culture as 'positive or negative', and (4) cultures of the unprepared skin surface can be predictive of the results of cultures of the freshly incised dermis.

The results of preoperative cultures of specimens from the unprepared skin surface may be helpful for anticipating the risk of positive intraoperative dermal wound-edge cultures that may, in turn, have a bearing on the risk of prosthetic bacterial colonization. This simple test may help to identify patients who may or may not merit more aggressive topical and systemic antibiotic prophylaxis
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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

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

See from which cities our patients come.

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Wednesday, February 14, 2018

What is stress shielding?

Stress shielding of the humerus in press-fit anatomic shoulder arthroplasty: review and recommendations for evaluation

Stress shielding has been defined as "Osteopenia occurring in bone as the result of removal of normal stress from the bone by an implant"

These authors point out that a wide variety of humeral implants and implant fixation methods are now available, each of which has the potential for changing the distribution of loads applied to the humerus. Over time, changes in load distribution can be expected to produce changes in the bone - some areas will developed increased density while others will loose bone density. These changes are commonly referred to as 'stress shielding'. The clinical effects of stress shielding (symptoms, risk of fracture, etc) are not well documented.

In this report the authors review the current literature on press-fit fixation of the humeral component during total shoulder arthroplasty and propose minimum requirements for radiographic descriptions of stress shielding of the humeral component during total shoulder arthroplasty and propose minimum requirements for radiographic descriptions of stress shielding.

Signs of stress shielding are thought to include cortical thinning, osteopenia, spot welds, and condensation lines. The challenge is that each of these is not an 'all or none' characteristic; each has at least 50 shades of grey. The authors offer these two examples of medial calcar osteolysis (blue arrow) 2 years after a total shoulder arthroplasty and osteopenia and proximal lateral cortical thinning (green arrow) 2 years postoperatively.


 
 







The challenges in diagnosing 'stress shielding' are (1) the radiographic appearance can be altered by the technique of the X-ray

 

(2) it is difficult to determine the degree to which the findings were present prior to the arthroplasty and 
(3) characteristics like cortical thinning and osteopenia are difficult to quantitate on plain films.

We conclude that diagnosing the presence and degree of  'stress shielding' can be a challenge.

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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

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

See from which cities our patients come.

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How to track progress of patients having a ream and run when they live over 1,000 miles away

For us, the key to closely following patients after the ream and run is the 'lateral supine photo'.
Here are three examples

1 day post op after second side ream and run (first done 6 months ago) - 2018 miles away

1 day post op after second side ream and run (first done 3 years ago) - 2327 miles away

3 weeks post op - 1438 miles away
                                   

The point is that with this simple photo - which can be sent by cell phone - we can track progress and make changes in the rehabilitation program as needed. With this approach, the distance becomes irrelevant.

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The reader may also be interested in these posts:



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

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

See from which cities our patients come.

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

Tuesday, February 13, 2018

Glenoid component loosening

Sequential 3-dimensional computed tomography analysis of implant position following total shoulder arthroplasty

These authors used  3-dimensional computed tomography (CT) to evaluate glenoid component position over time in 20 patients with minimum 2-year follow-up. They obtained scans (1) before surgery, (2) within two weeks after surgery and (3) at a minimum of 2-years after surgery.

Glenoids with evidence of component shift and/or central peg osteolysis were considered at risk of loosening. 

Of the patients, 7 (35%) showed evidence of glenoid components at risk of loosening, 6 with component shift (3 with increased inclination alone, 1 with increased retroversion alone, and 2 with both increased inclination and retroversion). 

Significantly more patients with glenoid component shift had central peg osteolysis compared with those without shift (83% vs 7%, P = .002).



Comment: It is surely of concern that more than one third of these patients having total shoulder arthroplasty were characterized as being at risk for glenoid component loosening.

Some of the findings in the Table S1 were interesting:
Type A glenoids tended to be at increased risk for loosening:
    Of 11 type A glenoids, 4 were at risk for loosening.
    Of 7 type B or C glenoids, only 1 was at risk for loosening.

Posteriorly augmented glenoid components tended to be at increased risk for loosening:
    Of 14 standard glenoid components, 4 were at risk for loosening
    Of 6 posteriorly augmented glenoid components, 3 were at risk for loosening.

Retroverted glenoids tended to at lower risk for loosening.

While these differences did not attain statistical significance with the small number of cases, these trends merit further observation in that they challenge some of the commonly held tenets.

The increases in inclination noted are of interest as well. Perhaps they were related to cuff failure allowing the humeral head to migrate upwards resulting in the rocking horse phenomenon. Loading of the superior glenoid can also result from superior positioning of the humeral component.

Here are some of their findings as seen on plain films. Note the narrowed acromiohumeral interval on the 'at risk glenoid' on the left.




Finally, this study requires each patient to have three CT scans, imaging that comes at a cost in terms of dollars and in terms of radiation exposure to the patient.

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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.

Click here to see the new Shoulder Arthritis Book.

Click here to see the new Rotator Cuff Book

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'

See from which cities our patients come.

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