Wednesday, January 18, 2017

Considering the Load of Propionibacterium in Revision Shoulder Arthroplasty

Characterizing the Propionibacterium Load in Revision Shoulder Arthroplasty
A Study of 137 Culture-Positive Cases

There has been a tendency in the recent literature to report cultures obtained at revision shoulder arthroplasty as being 'positive' or 'negative' or to assign revised shoulders to arbitrarily defined categories, in some cases distinguished by a single culture result (see below).



These authors took a different approach, one that considered the semi-quantitative results of all the cultures obtained from a revised shoulder - the 'load' of bacteria recovered from the shoulder using a defined culturing protocol.

They studied 137 revision shoulder arthroplasties from which a minimum of 4 specimens had been submitted for culture and that had at least 1 was positive for Propionibacterium. Standard microbiology procedures were used to assign a semiquantitative value (0.1, 1, 2, 3, or 4), called the Specimen Propi Value, to the amount of growth in each specimen. The sum of the Specimen Propi Values for each shoulder was defined as the Shoulder Propi Score, which was then divided by the total number of specimens to calculate the Average Shoulder Propi Score.

They found that the number and percentage of positive specimen-specific cultures (of material obtained from the stem explant, head explant, glenoid explant, humeral membrane, collar membrane, other soft tissue, fluid, or other) per shoulder ranged from 1 to 6 and 14% to 100%. A high percentage of specimens (mean, 43%; median, 50%) from the culture-positive shoulders showed no growth. These observations indicate that Propionibacterium are not evenly distributed through the tissues and implants of a failed shoulder arthroplasty so that more than a few samples are necessary to detect the presence of bacteria.

Another interesting finding was that the type of specimen submitted for culture affected the likelihood of culture positivity. Only 32.6% of the fluid cultures were positive in comparison with 66.5% of the soft-tissue cultures and 55.6% of the cultures of explant specimens. The average Specimen Propi Value (and standard deviation) for fluid specimens (0.35 ± 0.89) was significantly lower than those for the soft-tissue (0.92 ± 1.50) and explant (0.66 ± 0.90) specimens (p < 0.001). This finding provides a possible explanation for the limited utility of a culture-negative joint fluid aspiration in ruling out an infection.

A third intestine finding was the inter-sex difference in Propionibacterium load recovered from revised shoulders. The Shoulder Propi Score was significantly higher in men (3.56 ± 3.74) than in women (1.22 ± 3.11) (p < 0.001). Similarly, men had a significantly higher Average Shoulder Propi Score (0.53 ± 0.51) than women (0.19 ± 0.43) (p < 0.001).

Finally. the authors found that the percent of cultures positive for Propionibacterium varied widely among the cases with no apparent 'threshold' that could be used to distinguish 'definite infection' from 'probable infection' or 'probable contaminant' (see below).





Comment: This study provides an approach for standardizing:
(1) the harvesting of specimens = five samples of explants or tissue
(2) the culturing of specimens = aerobic and anaerobic media
(3) the period of observation = at least 17 days
(4) the reporting of culture results = Specimen Propi Value, Shoulder Propi Score and Average Shoulder Propi Score.

Such standardization and objective presentation of the results may facilitate comparison among investigators with respect to the characteristics of revised shoulder arthroplasties and the effectiveness of different surgical and medical approaches to their management.

An informed commentary on this article can be found at "The Emperor May Truly Have New Clothes" J Bone Joint Surg Am, 2017 Jan 18; 99 (2): e7 . https://doi.org/10.2106/JBJS.16.01148
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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 shoulderreverse total shoulder patient information,  CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

Humeral component eccentricity - getting it right

A 70 year old patient presented with painful clunking in the left shoulder after a prior arthroplasty. The anteroposterior view shown below indicates well fixed humeral and glenoid components. 


However, the 'truth' view, revealed a posteriorly sublimated humeral head that had been placed with the eccentricity directed posteriorly.

At the revision surgery, we found that the glenoid component was well fixed, but that the posterior glenoid polyethylene was severely eroded. We removed the glenoid component, smoothed the residual glenoid bone, placed an anteriorly eccentric humeral component, and performed a rotator interval plication.

At surgery and as seen in the postoperative 'truth' view,  the shoulder is now posteriorly stable.
Comment: This case demonstrates the value of the 'truth' view as well as the importance of proper orientation of humeral head eccentricity.

More about the 'truth' view can be seen here,  here, and here.

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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 shoulderreverse total shoulder patient information,  CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.




Monday, January 16, 2017

RSA - how useful are finite element models?


Quantifying the competing relationship between adduction range of motion and baseplate micromotion with lateralization of reverse total shoulder arthroplasty

These authors created a finite element model





of a specific reversed total shoulder glenoid fixation system in which there is a concern that micromotion may impair fixation to the hydroxyapatite central peg.



The model makes assumptions about the glenoid anatomy, bone quality and extent of reaming based on non-arthrtic cadaver glenoids




Using this model they found that lateralization of the glenoid significantly increased micromotion (p=0.015) and adduction ROM (p=0.001). Using two, versus four, baseplate fixation screws significantly increased micromotion (p=0.008). 

Comment: These results apply to a specific design of implant placed in a shoulder with specific anatomic and material properties. Looking at the second figure above, it seems intuitive that placing the glenoid component more laterallly will increase the range of adduction before contact between the lateral scapula and medial humerus occurs. It also seems intuitive that if the design is sensitive to micromotion (i.e. the fixation of the baseplate is not secure until progressive bony attachment occurs over time) that more screws would lead to less micromotion. 

Other designs of reverse total shoulder  (see below) have built-in lateral glenoid offset and achieve secure immediate fixation by a central compressive screw that penetrates the cortical bone of the subscapularis fossa rather than an ingrowth central post placed in the cancellous bone of the glenoid neck.


In our practice, we find that lateral glenosphere offset, more anatomic glenohumeral relationships, and immediate fixation of the glenosphere with a strong compressive screw that penetrates cortical bone enable the management of most pathologies requiring a reverse total shoulder.

Our reverse total shoulder technique is shown in this link.


Sunday, January 15, 2017

Pseudoparalysis - what is it and how should it be treated?

Cost-Effectiveness of Arthroscopic Rotator Cuff Repair Versus Reverse Total Shoulder Arthroplastyfor the Treatment of Massive Rotator Cuff Tears in Patients With Pseudoparalysis and Nonarthritic Shoulders

These authors define pseudoparalysis as a condition of the shoulder with active elevation of less than 90 in association with full passive elevation. They performed a Markov decision model analysis for the cost effectiveness of treatment of shoulders with pseudoparalysis without osteoarthritis, in other words the patients in question did not have cuff tear arthropathy. They compared  arthroscopic rotator cuff repair (ARCR) to reverse total shoulder arthroplasty (RTSA).

They found that for the base-case scenario(60-year-old patient), ARCR with conversion to RTSA on potential failure was the most cost-effective strategy when they assumed equal utility for the ARCR and RTSA health states. Primary RTSA became cost-effective when the utility of RTSAexceeded that of ARCR by 0.04 quality-adjusted life-years per year. Age at decision did not substantially change this result. These results are shown in the table below.



Comment: This article is important because it challenges the common paradigm that reverse total shoulder is the indicated treatment for most cases of pseudo paralysis.

Instead, this article is based on the assertions that (1) pseudo paralysis can be reversed without a reverse total shoulder, (2) reverse total shoulders are more expensive than non-prothesthetic approaches to pseudoparalysis, and (3) reverse total shoulders can have more serious and more expensive complications than non-prosthetic approaches to pseudoparalysis.

With these assumptions, their model suggests that an arthroscopic attempt to improve the integrity of the rotator cuff followed by a period of rest and rehabilitation is a more cost-effective alternative than a primary reverse total shoulder.

In trying to understand Markov model formulations, it is important to consider the utilities of the two treatments. Here the health related quality of life (HRQoL) for each treatment experienced over time was accumulated into quality-adjusted life-years (QALYs).

In this case these utilities were gathered from a small number of studies. 

The 2 studies included for RTSA utility reported on largely female (approximately 75%) and elderly (mean age 75 years) samples and found a mean HRQoL of 0.68 after RTSA.

The 4 studies included for arthroscopic cuff repair reported on relatively younger (mean age 55 years) and predominantly male (approximately 43% female) undergoing ARCR to find an average HRQoL of 0.78. None of these studies evaluated the integrity of the cuff after repair, so although the authors state that they were 'clearly able to repair' massive cuff tears, the durability of these attempted reattachments of the tendons to their insertion site has not been determined. In one of these studies  (see this link), the pseudoparalysis was acute, having been present for a mean of 3.9 months before surgery and was traumatic in origin in 45 (80.4%) patients. 

Lacking a clear best estimate for utility after RTSA and ARCR in an equivalent patient set, the authors arbitrarily assumed an equal base case HRQoL of 0.788 for both RTSA and ARCR. It is left to the reader to determine whether this assignment is reasonable.

Here are some other elements of the model





These authors have created a model based on available data. We suspect that they will continue to refine the model as more data become apparent so that it can develop into useful practice guidelines.

Such studies need to be interpreted with care as shown in this link, which points out that the sophisticated mechanics of the Markov model cannot compensate for uncertain assumptions.

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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'









Saturday, January 14, 2017

A ream and run rehabilitation program developed by a patient who's also a PT

Post-op Rehabilitation Protocol for Patients after the Ream & Run Procedure
Provided by

Congratulations on completing your ream and run procedure!  In an effort to help you recover function as quickly as possible, this is a post-op protocol developed and used by physical therapist Colin Hoobler, PT, DPT, MS, who had a ream and run procedure at the University of Washington. This program includes strengthening, stretching and endurance exercise. 

Note: This is the program used by Dr. Hoobler to successfully rehabilitate his shoulder. Patients having the ream and run procedure should discuss this program with their surgeon before implementing it.

Before starting, let’s review key concepts essential to your rehabilitation program.

1.     “Rate of Perceived Exertion” (RPE)

RPE reflects how intensely you feel an activity and protects you from injury, promotes efficiency and guides program progression so that you are challenged at an appropriate level. For every exercise you perform, you should know what your RPE should be before starting and self-monitor during the exercise.

We use a 0 to 10 version:

10        maximum
9
8         
7          very hard
6
5          hard
4          somewhat hard
3          moderate
2          light
1          very light
0          nothing

For example, if you walk at a leisurely pace you may feel an RPE level of 3 out of 10.  If you start running, you may increase to an RPE level 7 out of 10.

If you are exercising independently, pay close attention to where you are on this scale so that you push hard enough to improve but without injury.

If you are in physical therapy, your physical therapist (PT) will monitor your RPE to ensure safety, effectiveness and proper progression. 

2.     Repetitions

The number of repetitions you perform depends on many factors (e.g., resistance, motivation, technique) and must be monitored.  For example, if you want to achieve an RPE of 7 (i.e., “very hard”) out of 10 doing a strengthening exercise, we recommend doing a minimum of 25 repetitions with perfect technique when you’re cleared to initiate strengthening exercise (usually around 6 weeks post-op).  Therefore, a resistance must be selected to allow 25 repetitions.  If you cannot reach 25 repetitions, you are using too much resistance and should cut back. 

The tempo of your repetitions is important to protect against injury while promoting strength and coordination.  We recommend counting “one thousand one…” for each of the up and down phases to keep you within this range.  Avoid sudden, jerking repetitions to minimize injury risk!

3.     Sets

A set is a number of repetitions.  For example, doing 1 set of 25 repetitions should take about one minute and might reach an RPE of 6 out of 10.

4.     Specific Adaptation to Imposed Demand (SAID principle)

The SAID principle is a key sports medicine concept that will guide your rehabilitation program from the start and refers to your body’s ability to adapt to imposed stress. The SAID principle is a range of progress (adaptation) that correlates to RPE (i.e., RPE):

-----------------------------------------------------------------------------------------------------------
No stress        Some stress        Considerable stress       A lot of stress       Too much stress
No progress       Some progress         Considerable progress         A lot of progress         High injury risk!

In other words, exercise too little or not hard enough, and progress will be slow; exercise regularly and with moderate to high intensity and enjoy regular progress, but exercise with “excessive” intensity and injury risk skyrockets.  The goal is to exercise at an intensity that promotes progress but not too intensely so as to avoid injury.

You are the most vulnerable immediately after surgery, particularly your subscapularis muscle, which was cut during surgery.  Your rehabilitation program protects your subscapularis tendon at the start, then gradually stresses it more as you get farther away from your surgery date.  Gradual stress is key to help tissues heal and avoid injury. 
  
Begin Immediately

DAILY:
·      Low load, prolonged stretching into shoulder elevation
Position your arm onto a firm surface until you achieve a stretch intensity of 2/10 (i.e., “light”) and hold for 8 minutes up to 10 minutes, 2 times/day (yes, minutes). Make sure the palm is either facing upward or the thumb is pointed toward the ceiling (avoids compression of sensitive tissues in your shoulder).

·      Endurance exercise
Perform the elliptical, stairmaster, treadmill and/or stationary bike for 10 minutes/day at an intensity of 4/10.  Move your arms naturally and keep your shoulders back (i.e., maintain an erect posture).

  Work your way from walking to a slow jog to minimize shoulder stress.  Keep shoulders back and avoid shrugging.
·      
SShoulder external rotation (ER) isometrics
To start, stand up tall, pull your shoulder blades back and slightly move your elbow away from your body.  Holding this position, slowly push the back of your surgical side’s hand against a wall and hold for 30 seconds, achieving an RPE of 4 out of 10.  Repeat 5 times during the day. 



·      Shoulder pulley
To start, sit up tall, pull your shoulders blades back and grab the pulley handles with your palms facing upward. Slowly raise your surgical arm by pulling gently with your non-surgical arm, going as high as possible.  Repeat 50 times daily.


Notice position of the hand.  Keep shoulders back and avoid shrugging.

2 weeks

DAILY:
·      Continue long stretch, endurance exercise, ER isometrics and pulley
Hold your long stretch 12 minutes, perform endurance exercise for 15 minutes and increase your ER isometric RPE to 5 out of 10.
·      Counter squat with hip stretch between sets
See picture of counter squat and do 1 set of 30 repetitions, or achieve an RPE of 5 out of 10.  After the set, stretch your hip (each side) for 60 seconds, achieving an RPE of 5 out of 10.


·      Abdominal crunch
See picture of abdominal crunch exercise and do 1 set of 40 repetitions, or achieve an RPE of 5 out of 10.


Keep shoulders back, head up and belly in.

Calf stretch
See picture of calf stretch and do 1 set of a 60-second hold, or achieve an RPE of 5 out of 10.



6 weeks

DAILY:
·      Continue long stretch twice per day and endurance exercise
·      Continue other exercises and stretches
·      Add quad and hamstring stretches between squat sets
See pictures of quad and hamstring stretches and do 1 set of a 60-second hold each, or achieve an RPE of 5 out of 10. 



Minimize arching of your low back. Hold onto a stable object and stand tall.


8 weeks

DAILY:
·      Continue long stretch twice per day and endurance exercise
·      Continue other exercises and stretches
·      Add eccentric loading of shoulder ER using cable or thera-band
See picture of eccentric loading of shoulder ER exercise and do 1 set of 10 repetitions (each repetition will take 5 seconds), or achieve an RPE of 4 out of 10.


10 weeks

DAILY:
·      Continue long stretch once per day and endurance exercise
·      Continue prior exercises and stretches
·      Add seated row, lat pulldown
See videos of seated row and lat pulldown exercises at c.h. Physical Therapy and do 1 set of 25 repetitions each, or achieve an RPE of 4 out of 10.

12 weeks

DAILY:
·      Continue long stretch once per day and endurance exercise
·      Replace counter squat with lunge exercise
See video of lunge exercise at c.h. Physical Therapy and do 1 set of 25 repetitions each, or achieve an RPE of 5 out of 10.
·      Replace eccentric loading of shoulder ER exercise with shoulder ER exercise
See video of shoulder ER exercise c.h. Physical Therapy and do 2 sets of 25 repetitions, or achieve an RPE of 5 out of 10.

14 weeks

DAILY:
·      Continue long stretch once per day, endurance exercise
·      Return to desired activity at limited duration/intensity per your surgeon
·      Add push-up hold exercise
See picture of push-up hold exercise and do 1 set of a 30-second hold.



When your surgeon gives the OK, you might consider other exercises on the website c.h. Physical Therapy