Tuesday, June 27, 2017

What is an infection anyway?

Medical comorbidities and perioperative allogeneic red blood cell transfusion are risk factors for surgical site infection after shoulder arthroplasty

These authors sought to determine surgical site infection (SSI) risk due to medical comorbidities or blood transfusion after primary or revision shoulder arthroplasty. They collected data on medical comorbidities, surgical indication, perioperative transfusion, and SSI were obtained for 707 patients who underwent primary or revision hemiarthroplasty or total shoulder.

For the purpose of this study, SSI was defined in a rather particular manner:  either (1) treatment of a superficial infection within 30 days of surgery with d├ębridement by the treating surgeon or with antibiotics by either the treating surgeon or an infectious disease specialist or (2) treatment of a suspected or confirmed deep infection by return to the operating room for d├ębridement, component exchange, or explantation of components or treatment with therapeutic or long-term suppressive antibiotics by an infectious disease specialist. Positive cultures on return to the operating room were not a requirement for diagnosis of SSI.

Using this set of definitions, the SSI rate was 1.9% for primary hemiarthroplasties and 1.3% for primary total shoulder arthroplasties.

Revision arthroplasty or prior open reduction and internal fixation had higher SSI risk than primary arthroplasties (incidence risk ratio [IRR], 11.4; 95% confidence interval [CI], 3.84-34.0; P < .001).

Among primary arthroplasties, SSI risk factors included male gender (IRR, 60.0; CI, 4.39-819; P = .002), rheumatoid arthritis (IRR, 8.63; CI, 1.84-40.4; P = .006), and long-term corticosteroid use (IRR, 37.4; CI, 5.79-242; P < .001). 

Perioperative allogeneic red blood cell transfusion significantly increased SSI risk and was dose dependent (IRR, 1.68 per unit packed red blood cell; CI, 1.21-2.35; P = .002).

The culture results are shown below.



Comment: This series of cases points to the complex and uncertain relationship between cultures and clinical findings. Patients without the characteristic signs of infection can have positive cultures. Patients with characteristic signs of infection can have negative cultures.

The culture protocol used for these patients is not explained. Specifically, we do not know which cases were cultured, how many specimens were submitted for culture, what culture media were used, and how long the cultures were observed. It is known that unless 5 deep specimens are cultured on three different media and observed for 3 weeks, there is a substantial risk of overlooking Propionibacterium in the wound.

Here are some related posts:

Low-grade infections in nonarthroplasty shoulder surgery

These authors reviewed 35 patients presenting with suspected low-grade infection in which biopsy specimens taken at revision surgery. Patients presented with symptoms akin to resistant postoperative frozen shoulder (persistent pain and stiffness, unresponsive to usual treatments).



Positive cultures were identified in 21 cases (60.0%), of which 15 were male patients (71%). Of all patients with low-grade infection, half were male patients between 16 and 35 years of age.

Propionibacterium acnes and coagulase-negative staphylococcus were the most common organisms isolated (81.1% [n = 17] and 23.8% [n = 5], respectively).  The mean time from index surgery to diagnosis for P. acnes –positive cases was 1.2 years (60.3 weeks).









Not all patients with clinically suspected low-grade infections presentedwith positive microbiologic cultures, despite use of enhanced culture methods. The authors suggest that the suspect organisms may be nonculturable on routine culture media or that the suspect organism was in an area of the shoulder not sampled. Of 14 negative culture cases, 9 were treated with early empirical antibiotics (64.3%); 7 patients reported symptomatic improvement (77.8%). Of 5 patients treated with late empirical antibiotics, 4 stated improvement.  Again, the majority of the patients with negative cultures reported improvement in their pain, stiffness, and range of movement after early empirical antibiotic treatment (doxycycline and amoxicillin, n = 8 [88.9%]; gentamicin and teicoplanin, n = 1 [11.1%]). More than half of these patients (n = 6 [66.7%]) stated that their pain completely resolved

Comment: This series of cases points to the complex and uncertain relationship between cultures and clinical findings. Patients without the characteristic signs of infection can have positive cultures. Patients with negative cultures can respond to antibiotics.


For more, see the below:

These authors point out that while as many as 50% of revision shoulder arthroplasties are culture positive, a consistent, clinically useful definition of a "periprosthetic shoulder infection" is lacking. They conducted a systematic review of the published literature with respect to (1) the definition of a "periprosthetic shoulder infection", (2) the pre-operative evaluation for possible infection, and (3) the harvesting and culturing of specimens at the time of surgical revision.

They found a remarkable lack of consistency in the way different authors defined an 'infection', in the way authors evaluated patients with possible infections before surgery and in the way authors obtained and analyzed specimens obtained for culture harvested at the time of the surgical revision of failed shoulder joint replacements.

This inconsistency makes it very difficult to compare different treatment approaches to failed shoulder joint replacements, recognizing that some of them will have substantial bacteria in the joint, the presence of which may go unrecognized until the culture results are finalized at 2 to 3 weeks after surgery.

Comment: It is critically important not to combine, confuse or commingle data from 

"obvious infections" (i.e. those with swelling, redness, drainage, fever, chills, elevated serum markers of inflammation) where the diagnosis of infection is apparent 

with cases of 

"stealth" presentation (i.e. the unexplained onset of pain and stiffness of the shoulder after a 'honeymoon' of good function in which specimens obtained at revision surgery are strongly positive for organisms such as Propionibacterium).

Here's an example of a stealth presentation:

A 50 year old patient presented desiring a ream and run arthroplasty for severe glenohumeral arthritis



After surgery, the shoulder progressively regained comfort and function. Subsequently, however it started to become stiff and painful without obvious explanation. Eight years after his shoulder arthroplasty, the patient returned to the office with no clinical, laboratory, or radiographic evidence of infection.



A single stage revision was performed (soft tissue releases, prothesis exchange) without any evidence of inflammation, joint fluid, loosening, or osteolysis. Five explant and tissue cultures were sent. The patient was discharge on the yellow protocol (Augmentin) until the results of the cultures were final.

The culture results were
Humeral head explant: 3+ Propionibacterium
Humeral stem explant: no growth
Collar membrane: 1+ Propionibacterium
Humeral periosteum: 1+ Propionibacterium
Joint capsule: no growth

At this point the red protocol (IV ceftriaxone) was started and continued for 6 weeks followed by a 6 month course of Augmentin. The patient has a comfortable shoulder and has regained most of the lost shoulder motion.

Monday, June 26, 2017

Propionibacterium, benzoyl peroxide and clindamycin

Benzoyl peroxide and clindamycin topical skin preparation decreases Propionibacterium acnes colonization in shoulder arthroscopy

These authors enrolled 65 patients  in a study to investigate whether a benzoyl peroxide and clindamycin preoperative skin preparation reduces the incidence of P. acnes colonization in shoulder arthroscopy. A skin culture specimen was taken at the preoperative visit from standard arthroscopic portal sites. Topical benzoyl peroxide 5% and clindamycin 1.2% (BPO/C) gel was applied to the shoulder every night before surgery. Skin culture was repeated in the operating room before preparation with chlorhexidine gluconate. Final cultures were obtained from within the shoulder after the arthroscopic procedure.

All culture specimens were plated for a full 21 days on Brucella blood agar medium and reported to 21 days.

Initial culture specimens taken before treatment with topical BPO/C were positive for P. acnes in 31 of 65 patients (47.7%). Men (80.6%, 25 of 31 patients) were more often colonized than women (19.4%, 6 of 31 patients) (P = .001).

With 1 application of BPO/C,  4 of 12 (33%) patients were culture positive in the OR prior to skin preparation with chlorhexidine gluconate. 

4 of 19 (21%) patients having >1 application of BPO/C were culture positive in the OR prior to skin preparation with chlorhexidine gluconate. 

The positivity  of the deep cultures were associated with the number of applications; 0% of patients with 2 or more applications had a positive deep culture. 

The two patients had a positive deep culture had fewer than 2 applications of BPO/C . Interestingly, 4 patients who initially had negative skin cultures for P. acnes demonstrated positive skin cultures after topical BPO/C was used. These patients all had negative deep cultures.

Clinical follow-up was documented for all 65 patients for a minimum of 3 months and mean of 6 months postoperatively. There were no signs or symptoms of a clinical infection. Patients with positive deep P. acnes cultures were provided oral antibiotic treatment with doxycycline 100 mg daily for 3 weeks. The topical skin preparation was safe, with only 1 skin reaction (1.5% of patients.) There was no erythema or desquamation in this patient but rather a mild dermatitis. The reaction resolved promptly without treatment, and surgical timing did not need to be altered.


In a prior study, these authors reported on the prevalence of deep colonization of P. acnes in patients undergoing shoulder arthroscopy finding a 72.5% superficial culture rate and 19.6% deep inoculation rate. All positive deep cultures had positive superficial skin cultures.

Comment:  In their discussion, the authors state that "benzoyl peroxide is a powerful topical antimicrobial agent destroying both surface and ductal bacterial organisms and yeasts. Its lipophilic properties permit penetration of the pilosebaceous duct. Once applied to the skin, benzoyl peroxide decomposes to release free oxygen radicals, which have potent bactericidal activity in the sebaceous follicles and an antiinflammatory action. Treatment with BPO/C has demonstrated the added benefit of inhibiting the emergence of antibioticresistant strains of P. acnes."

There may be a downside to the use of BPO/C; the authors point out that "The application of the antibiotic gel in our study revealed positive skin cultures for P. acnes in 3 patients who initially had negative skin cultures. This may be secondary to the dual functions that benzoyl peroxide possesses. Benzoyl peroxide is a direct topical bactericidal agent that is also lipophilic. It penetrates pilosebaceous follicles to break down to benzoic acid and hydrogen peroxide, which releases free oxygen radicals that can oxidize proteins in bacterial cell membranes. Benzoyl peroxide is also known to act as a comedolytic and it is likely that this chemical exfoliating action on the epidermal layer of skin exposes the pathogen for culture."

This study would have been stronger if concurrent rather than historical controls were used (note the apparent difference in superficial culture results for the historical controls (72.5%) vs 47.7% in this study. "Because of changes in contracts, the laboratory used for the cultures had to be changed midway through the study for 16 patients. The second laboratory had a lower overall P. acnes –positive superficial culture incidence (6.3%) than expected from previous studies."

Nevertheless, the article is of interest in its proposal of a prophylactic regimen with BPO/C  as well as a proposal for using post operative doxclyline for patients with positive deep cultures (although these culture results were not finalized until 3 weeks after surgery so it appears that the antibiotics would not be started until these results were known). 

We are left with the thought that some patients may benefit from BPO/C prophylaxis before shoulder surgery. The questions that remain are (1) which patients are appropriate for BPO/C  treatment? (2) how many BPO/C  treatments are indicated? (3) if a patient has a skin reaction to BPO/C, how should that affect proceeding with elective surgery and  (4) when cultures are obtained before and at surgery, how should the results of these cultures inform the use of extraordinary antibiotic prophylaxis? 


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Healing through joint replacement

Wednesday, June 14, 2017

Ream and run for B2 glenoid at one year

A year ago a man in his mid 60s presented with a painful stiff right shoulder and a Simple Shoulder Test as recorded here: 



 He came with a CT scan showing a biconcave glenoid.

Because of his active lifestyle, he elected to proceed with a ream and run procedure.
At one year after surgery his SST score was 12/12 and his radiographs showed excellent centering and healing of his arthroplasty.




He was kind enough to allow us to take and show a video of his active shoulder motion.

video



He states that his shoulder is getting progressively stronger and more functional.

No bony ingrowth, no platform, no cement, no plastic.

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PROMIS - does it introduce selection bias?

Performance of PROMIS for Healthy Patients Undergoing Meniscal Surgery

The Patient-Reported Outcomes Measurement Information System (PROMIS) was developed as an extensive question bank with multiple health domains that could be utilized for computerized adaptive testing (CAT). These authors investigated the use of the PROMIS Physical Function CAT (PROMIS PF CAT) in an otherwise healthy population scheduled to undergo surgery for meniscal injury with the hypotheses that (1) the PROMIS PF CAT would correlate strongly with patient-reported outcome instruments that measure physical function and would not correlate strongly with those that measure other health domains, (2) there would be no ceiling effects, and (3) the test burden would be significantly less than that of the traditional measures. 

Patients scheduled to undergo meniscal surgery completed the PROMIS PF CAT, Knee injury and Osteoarthritis Outcome Score (KOOS), Marx Knee Activity Rating Scale, Short Form-36 (SF-36), and EuroQol-5 Dimension (EQ-5D) questionnaires. Correlations were defined as high (‡0.7), high-moderate (0.61 to 0.69), moderate (0.4 to 0.6), moderateweak (0.31 to 0.39), or weak (£0.3). If ‡15% respondents to a patient-reported outcome measure obtained the highest or lowest possible score, the instrument was determined to have a significant ceiling or floor effect.
A total of 107 participants were analyzed. The PROMIS PF CAT had a high correlation with the SF-36 Physical Functioning (PF) (r = 0.82, p < 0.01) and KOOS Sport (r = 0.76, p < 0.01) scores; a high-moderate correlation with the KOOS Quality-of-Life (QOL) (r = 0.63, p < 0.01) and EQ-5D (r = 0.62, p < 0.01) instruments; and a moderate correlation with the SF-36 Pain (r = 0.60, p < 0.01), KOOS Symptoms (r = 0.57, p < 0.01), KOOS Activities of Daily Living (ADL) (r = 0.60, p < 0.01), and KOOS Pain (r = 0.60, p < 0.01) scores. The majority (89%) of the patients completed the PROMIS PF CAT after answering only 4 items. The PROMIS PF CAT had no floor or ceiling effects, with 0% of the participants achieving the lowest and highest score, respectively.

Comment: This study does not provide data on the cost and training necessary to implement the PROMIS CAT system. Basically it shows that the PROMIS CAT correlates well with free, universally available tools. While the authors conclude that "It may be a reasonable alternative to more burdensome patient-reported outcome measures," it may be actually the case that currently available and generally accepted inexpensive tools provide an alternative to the more burdensome PROMIS CAT. 

Implementing this system requires the provider to have access to a PROMIS CAT program for each diagnostic condition she or he manages and for the provider's patients to have access to the system each time they provide an update. As a result, the providers and the patients using PROMIS CAT are likely to be highly selected and not representative of the general practice of the specialty.  

We rely on 'inclusive' approaches to outcome assessment that put valid followup within the reach of the maximal number of providers and patients so that the information gained is as generalizable as possible.

See the related posts below.


Psychometric evaluation of the PROMIS Physical Function Computerized Adaptive Test in comparison to the American Shoulder and Elbow Surgeons score and Simple Shoulder Test in patients with rotator cuff disease

The National Institutes of Health has recently developed the Patient-Reported Outcomes Measurement System (PROMIS) Computer Adaptive Test (CAT) that applies technology of computerized adaptive testing used in examinations like the Graduate Records Examinations.
With CAT, questions are sequentially administered from a large item ‘‘bank’’ until predetermined reliability criteria are met. Each question response produces a probability curve of the respondent’s estimated ability. For example, a patient who can throw a ball with ease has a high probability of having upper-end physical function. Subsequent questions can then be chosen by the CAT ‘‘engine’’ that will further discriminate the respondent’s estimated ability while uninformative and repetitive questions are omitted.

These authors studied 187 patients with clinical diagnosis of rotator cuff disease completed the American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), and PF CAT.

Responses from 187 patients were analyzed. The PF CAT required fewer questions than the ASES or SST (PF CAT, 4.3; ASES, 11; SST, 12). Correlation between all instruments was moderately high. Item reliability was excellent for all instruments, but person reliability of the PF CAT was superior (0.93, excellent) to the SST (0.71, moderate) and ASES (0.48, fair). Ceiling effects were similar among all instruments (PF CAT, 0.53%; SST, 6.1%; ASES, 2.3%). Floor effects were found in 21% of respondents to the SST but in only 3.2% of PF CAT and 2.3% of ASES respondents.

Comment: Unfortunately the CAT requires the patient to be at a computer or tablet that carries the program. It cannot be completed on paper and thus is not amenable to follow-up mailings. The authors did not measure the time to complete the PROMIS nor its relative convenience or user-friendliness. They did not study the ability of the PROMIS responses to be translated into terms that patients can easily grasp. It is 'the new kid on the block' so that its results cannot be compared to data collected in the past.

By contrast the user-friendly Simple Shoulder Test can be completed on paper anywhere in the world in under two minutes and requires nothing other than a pencil. The SST has been utilized in over 650 publications according to a recent PubMed search. As early as ten years ago, it was recognized that this simple 12 item questionnaire had the ability to characterize (1) the function of normal shoulders, (2)  the functional deficits for many different diagnoses, and (3) the different responses of male and female patients. Here are some figures from that article that was based on 2674 patients.




Self-assessed outcome at two to four years after shoulder hemiarthroplasty with concentric glenoid reaming.

Shoulder scoring scales for the evaluation of rotator cuff repair.

It can be easily used to track patients' recovery over time.




As well as its use in multiple languages, for example


Validation and reliability of a Spanish version of Simple Shoulder Test (SST-Sp)

Finally, and perhaps most importantly, while the PROMIS score is a number without particular meaning to a patient, the results of the SST can be easily communicated:




Is the Simple Shoulder Test a valid outcome instrument for shoulder arthroplasty?

It is in the interest of all shoulder surgeons to document the functional status of their patients before and sequentially after treatment to learn what treatments are working for which diagnoses in which patients. Observing one's personal outcomes is a great way for a surgeon to continue to improve. The issue is that many of the existing instruments are time consuming, at risk for observer bias, unvalidated, and/or inflexible in terms of the patient's need to return to the office for evaluation.

These authors point out that the Simple Shoulder Test (SST - a 12 item 'yes' or 'no' questionnaire) is a brief, inexpensive, convenient, and widely used patient-reported outcome tool. Since it is the patient who should be served by our treatment, it makes sense to base the outcome assessment on the patient's self-assessed ability to perform shoulder functions.

The results are easy to record in the patient's medical record so that the trend over time can be easily followed. The12 individual questions of the SST allow a more detailed discussion of each patient's functional deficits and the likelihood that the desired function might be restored.

The SST does not require any potentially biasing participation by physicians, nurses, or therapists; it can be completed without a computer and without the patient’s having to return to the surgeon’s office. It has been adapted and validated in multiple languages, including Persian, Spanish, Portuguese, Dutch, and Turkish.

However, the SST has not been rigorously evaluated for patients treated with shoulder arthroplasty. The goal of their study was to rigorously evaluate the validity of the SST for outcome assessment in shoulder arthroplasty using a systematic review of the literature and an analysis of its properties in a series of 408 surgical cases. For these patients the authors documented SST scores, 36-Item Short Form Health Survey scores, and satisfaction scores collected preoperatively and 2 years postoperatively. The responsiveness of the SST was assessed by comparing preoperative and 2-year postoperative scores. The criterion validity of the SST was determined by correlating the SST with the 36-Item Short Form Health Survey. The construct validity of the SST was tested through 5 clinical hypotheses regarding satisfaction, comorbidities, insurance status, previous failed surgery, and narcotic use.

They found that scores improved from 3.9 ± 2.8 before arthroplasty to 10.2 ± 2.3 after arthroplasty (P < .001). The change in SST correlated strongly with patient satisfaction (P < .001). The SST had large Cohen’s d effect sizes and standardized response means. Criterion validity was supported by significant differences between satisfied and unsatisfied patients, those with more severe and less severe comorbidities, those with workers’ compensation or Medicaid and other types of insurance, those with and without previous failed shoulder surgery, and those taking and those not taking narcotic pain medication before surgery (P < .005).

They concluded that these data combined with a systematic review of the literature demonstrated that the SST is a valid and responsive patient-reported outcome measure for assessing the outcomes of shoulder arthroplasty.

Comment: A figure from this paper helps to make a point. The black arrows in the figure below indicate patients who did not fare so well after shoulder arthroplasty. These are the ones on which the surgeon needs to focus, asking - was the type of arthroplasty the right treatment, was it done well, was the rehab properly organized, were there other factors interfering with the desired outcome?


























The SST can also be useful in discussing with the patient "when is it the right time for a shoulder replacement for arthritis?" This question comes up often.




Of course, the answer depends on many things, including the degree to which the quality of life of the individual is impaired by the shoulder condition, the condition of the muscles, tendons, bone and nerves around the shoulder, the expectations of the patient, the overall health of the individual, the individual's willingness to accept the risks of surgery, and the degree of comfort the individual has with the surgeon.

We recently summarized the SST scores of over 2800 of our patients at the point where they had decided to have a shoulder joint replacement for their arthritis. The average preoperative SST score was 3.9. The numbers of patients with each of the 12 possible SST scores is shown below. Basically, this graph shows that 62% of patients having joint replacement had preoperative SST scores of 4 or below; 30% had SST scores from 5-8; and 8% had scores from 9-12.


We find this graph useful for allowing the patient to place their current self-assessed comfort and function in the context of other patients having shoulder arthroplasty.


One of the operations we offer to patients with shoulder arthritis is the ream and run procedure, a method of shoulder joint replacement arthroplasty that avoids the potential risks associated with a plastic socket.
The chart above shows how the Simple Shoulder Test (SST) is used to document the recovery of patient self-assessed comfort and function after a ream and run procedure for shoulder arthritis. The data represent the average recovery from a consecutive series of over 100 patients with at least two years of post surgical follow-up. The vertical axis represents the total number of SST questions answered 'yes', while the horizontal axis represents the years after surgery. The dots show individual data points and the lines show the average (plus or minus one standard deviation) for all the patients.
Since, on average, patients having the ream and run live over 500 miles from our center, routine office visits are impractical for them.  Because patients mail or email their results to us, we have been able to keep close tabs on their recovery using the Simple Shoulder Test.The full article was recently published in the JBJS and discussed in this post.


In conclusion, if "value" is defined as the benefit divided by the cost, the SST appears to be a high value assessment tool.
We are not sure that the PROMIS is progress.


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Total shoulder: pegged or keeled glenoid?

Comparison of Pegged and Keeled Glenoid Components for Total Shoulder Arthroplasty A Systematic Review

These authors conducted a systematic review of level I, II, and III studies comparing the development of radiolucent lines and glenoid failure after total shoulder arthroplasty with pegged or keeled glenoid components was conducted. Four articles were included in the final analysis with a total of 203 total shoulder arthroplasties comprising 107 pegged and 96 keeled glenoid components.

They found that the development of radiolucent lines was less likely with pegged glenoid components with a risk difference of −0.32 (95% CI −0.62, −0.03) favoring the pegged design. There was no statistically significant difference in the rate of radiographically at-risk glenoids, clinical glenoid failure, or the composite endpoint.

Comment: There are many factors that influence the survivorship of a glenoid component. First and foremost are (1) the quality of preparation of the glenoid bone that supports the component and (2) the soft tissue balancing that assures centering of the humeral component on the glenoid. With respect to pegs vs. keels,

it is important to recognize that all pegged designs are not alike. Some offer out of plane anterior and posterior pegs with a fluted central peg for bone ingrowth


while others offer only smooth pegs all in the same plane.

Such differences can confound the comparisons published in the literature. 

While it is technically more demanding, we prefer a pegged glenoid with a central fluted peg because it offers ingrowth fixation without a metal back and because it preserves the glenoid bone stock that is lost when a slot is created for a keeled component.

Our approach to glenoid arthroplasty briefly described here.
The goals for total shoulder arthroplasty include establishing maximal stability and maximal contact area for distribution of the humeral load to the glenoid. In addition, the procedure needs to achieve support of the prosthetic glenoid by precisely contouring the bone supporting it as well as secure and durable fixation of the component to the underlying bone. In that glenoid bone stock is a most precious commodity when performing shoulder arthroplasty and in that excessive reaming has been associated with increasing rates of glenoid component failure, preservation of glenoid bone is a high priority. Both bone preservation and the quality of fixation are enhanced by the precise drilling of the holes for peg fixation of a glenoid component rather than the less precise preparation for a keeled component. This precision has the additional benefit of minimizing the amount of cement used, reducing the risk of thermal damage.

The glenoid is exposed by excising the labrum from the bony glenoid, removing any tissue that may interfere with complete glenoid component seating. If the preoperative axillary view shows posterior humeral head decentering, the inferior glenohumeral capsule is left intact.

The size of the glenoid component is determined using round back glenoid trials. The center of the glenoid face is marked and a burr hole is made at this point to guide the drill for the reamer. The angle of glenoid reaming is adjusted to preserve as much glenoid subchondral bone as possible. Glenoid bone is preserved by orienting the reaming and the component along the glenoid axis rather than the scapular axis. Reaming is always started by hand; power is used very sparingly except in hard bone. Appropriate positioning of retractors facilitates this reaming. In that the goal of reaming is to conservatively establish a single glenoid concavity, it is important to check the progress of reaming frequently so that the reamer does not inadvertently remove more bone than necessary. The adequacy of the glenoid bone preparation is checked by inserting the round back glenoid trial component and ensuring that it does not rock even when eccentric loads are applied to the rim.

After the hole for the central peg is drilled, the peripheral drill guide is inserted into the central peg hole and set firmly on the reamed glenoid surface to precisely guide the drilling of the additional holes for the peripheral pegs. The drill guide needs to be oriented to take maximal advantage of the available glenoid bone; care must be taken to assure that the drill guide sits flush on the reamed glenoid surface so that the hole position will match the position of the component pegs. After each peripheral hole is drilled, a derotation peg is placed in it to maintain alignment of the guide while the subsequent holes are completed and to make sure that the hole is of the proper depth. Each hole is checked to determine whether it penetrates the scapula.

After irrigation with antibiotic containing saline solution, the holes are cleaned and dried with a spray of sterile CO2 gas removing all tissue and fluid from the holes so that the injected cement will directly contact bone without interposed fluid or the blood clot that results from the use of thrombin. It is apparent that neither fluid nor clot will turn into bone or cement, so the presence of either will compromise the quality of fixation.



Unpenetrated holes are pressurized with a syringe. Penetrating holes are cemented, but the cement is not pressurized. The use of a carbon dioxide gas spray and cement pressurization has essentially eliminated the problem of postoperative radiolucent lines


 




No cement is placed on the bony face of the glenoid; if the back of the glenoid component matches the prepared bony face, there is no advantage to an interposed layer of cement, which could fail and become displaced and consequently leave the glenoid component relatively unsupported as shown below.


While some surgeons have been concerned about avoiding penetration of the holes for glenoid fixation, glenoid perforation does not appear to affect the clinical outcome of total shoulder arthroplasty. It is evident, however, that penetration is more likely in severely pathological glenoids that have substantial medial or posterior bone erosion and for this reason, rather than the penetration itself, shoulder arthroplasty may be less successful in cases of particularly severe arthritic deformity.

Reamed bone retrieved during the glenoid preparation (reaming and drilling) is used to create a bone paste that is interposed between the flutes of the central anchor peg to help facilitate bone tissue integration. The glenoid component is firmly impacted into position, assuring that its posterior aspect is completely seated on bone by sliding a finger over the back of the component to feel the bone that should lie immediately beneath. The joint space is checked to assure that no bits of cement or bone remain. From the time the glenoid component is in place, it is important to prevent the humerus from dislodging it by the ‘bottle cap’ mechanism; we use a broad flat retractor to safely deliver the proximal humerus into the wound after the glenoid has been implanted.

Here is a related post: Rates of Radiolucency and Loosening After Total Shoulder Arthroplasty with Pegged or Keeled Glenoid Components

There is no question that survivorship of the glenoid component is the key to survivorship of a total shoulder arthroplasty. We have presented our approach to glenoid arthroplasty here.


This is an important study in that it seeks literature evidence on the cost-effectivenss of pegged vs. keeled glenoid components with particular emphasis on the risk of revision surgery. After a thorough analysis of the published data, they found that pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). Their value analysis indicated that pegged glenoid designs were more cost-effective than keeled glenoid designs.

One of the key differences between a pegged and keeled component is that with a pegged component the geometry of the fit is more precisely controlled by the fact that concentric reaming takes place around the same axis as is used to fix the component.

Thus the risk of poor bony support for the component (shown below) is reduced. 



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Tuesday, June 13, 2017

What does it take to repair the subscapularis after a TSA?

Healing and functional outcome of a subscapularis peel repair with a stem-based repair after total shoulder arthroplasty

These authors point out that the post total shoulder (TSA) integrity and function of the subscapularis is dependent on surgical technique. While some authors have advocated a lesser tuberosity osteotomy, they point out that this method violates the proximal humeral bone integrity, this technique may be of concern during placement of the humeral stem. They report the results with a prosthesis-specific approach to reattaching the subscapularis after TSA using holes in the implant.



They present minimum one year followup outcomes in 60 cases treated with a subscapularis peel which is repaired to the stem  after total shoulder arthroplasty (TSA). The long head biceps tendon was routinely sacrificed and tenodesed.

The clinical outcomes of these arthroplasties were good: the Simple Shoulder Test scores showed significant improvement from 4.3 to 10.2, (P < .001). 
On ultrasound examination, the subscapularis was healed intact in 55 cases (91.7%), attenuated in 3 cases (5%), and torn in 2 cases (3.3%). 

Comment: The integrity of the subscapularis depends on four key elements:
(1) the pre-incision quality of the tendon
(2) the technique with which it is incised from the humerus - important to preserve the integrity of the subjacent capsule to offer a robust tendon edge for reattachment
(3) the security of the reattachment to bone, and
(4) the rehabilitation of the shoulder in a way that protects the subscapularis repair from external rotation stretching or active internal rotation loads.

Our surgical approach to subscapularis management can be used with any prosthesis. It 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. The security each suture is verified to make sure it does not pull through the bone.

 These sutures are then passed through the tendon edge, including the capsule retained on its deep surface, 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

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Friday, June 9, 2017

Documenting shoulder comfort and function in the context of a busy practice

Is the Simple Shoulder Test a valid outcome instrument for shoulder arthroplasty?

It is in the interest of all shoulder surgeons to document the functional status of their patients before and sequentially after treatment to learn what treatments are working for which diagnoses in which patients. Observing one's personal outcomes is a great way for a surgeon to continue to improve. The issue is that many of the existing instruments are time consuming, at risk for observer bias, unvalidated, and/or inflexible in terms of the patient's need to return to the office for evaluation.

These authors point out that the Simple Shoulder Test (SST - a 12 item 'yes' or 'no' questionnaire) is a brief, inexpensive, convenient, and widely used patient-reported outcome tool. Since it is the patient who should be served by our treatment, it makes sense to base the outcome assessment on the patient's self-assessed ability to perform shoulder functions.

The results are easy to record in the patient's medical record so that the trend over time can be easily followed. The12 individual questions of the SST allow a more detailed discussion of each patient's functional deficits and the likelihood that the desired function might be restored.

The SST does not require any potentially biasing participation by physicians, nurses, or therapists; it can be completed without a computer and without the patient’s having to return to the surgeon’s office. It has been adapted and validated in multiple languages, including Persian, Spanish, Portuguese, Dutch, and Turkish.

However, the SST has not been rigorously evaluated for patients treated with shoulder arthroplasty. The goal of their study was to rigorously evaluate the validity of the SST for outcome assessment in shoulder arthroplasty using a systematic review of the literature and an analysis of its properties in a series of 408 surgical cases. For these patients the authors documented SST scores, 36-Item Short Form Health Survey scores, and satisfaction scores collected preoperatively and 2 years postoperatively. The responsiveness of the SST was assessed by comparing preoperative and 2-year postoperative scores. The criterion validity of the SST was determined by correlating the SST with the 36-Item Short Form Health Survey. The construct validity of the SST was tested through 5 clinical hypotheses regarding satisfaction, comorbidities, insurance status, previous failed surgery, and narcotic use.

They found that scores improved from 3.9 ± 2.8 before arthroplasty to 10.2 ± 2.3 after arthroplasty (P < .001). The change in SST correlated strongly with patient satisfaction (P < .001). The SST had large Cohen’s d effect sizes and standardized response means. Criterion validity was supported by significant differences between satisfied and unsatisfied patients, those with more severe and less severe comorbidities, those with workers’ compensation or Medicaid and other types of insurance, those with and without previous failed shoulder surgery, and those taking and those not taking narcotic pain medication before surgery (P < .005).

They concluded that these data combined with a systematic review of the literature demonstrated that the SST is a valid and responsive patient-reported outcome measure for assessing the outcomes of shoulder arthroplasty.

Comment: A figure from this paper helps to make a point. The black arrows in the figure below indicate patients who did not fare so well after shoulder arthroplasty. These are the ones on which the surgeon needs to focus, asking - was the type of arthroplasty the right treatment, was it done well, was the rehab properly organized, were there other factors interfering with the desired outcome?


























The SST can also be useful in discussing with the patient "when is it the right time for a shoulder replacement for arthritis?" This question comes up often.




Of course, the answer depends on many things, including the degree to which the quality of life of the individual is impaired by the shoulder condition, the condition of the muscles, tendons, bone and nerves around the shoulder, the expectations of the patient, the overall health of the individual, the individual's willingness to accept the risks of surgery, and the degree of comfort the individual has with the surgeon.

We recently summarized the SST scores of over 2800 of our patients at the point where they had decided to have a shoulder joint replacement for their arthritis. The average preoperative SST score was 3.9. The numbers of patients with each of the 12 possible SST scores is shown below. Basically, this graph shows that 62% of patients having joint replacement had preoperative SST scores of 4 or below; 30% had SST scores from 5-8; and 8% had scores from 9-12.


We find this graph useful for allowing the patient to place their current self-assessed comfort and function in the context of other patients having shoulder arthroplasty.

One of the operations we offer to patients with shoulder arthritis is the ream and run procedure, a method of shoulder joint replacement arthroplasty that avoids the potential risks associated with a plastic socket.
The chart above shows how the Simple Shoulder Test (SST) is used to document the recovery of patient self-assessed comfort and function after a ream and run procedure for shoulder arthritis. The data represent the average recovery from a consecutive series of over 100 patients with at least two years of post surgical follow-up. The vertical axis represents the total number of SST questions answered 'yes', while the horizontal axis represents the years after surgery. The dots show individual data points and the lines show the average (plus or minus one standard deviation) for all the patients.
Since, on average, patients having the ream and run live over 500 miles from our center, routine office visits are impractical for them.  Because patients mail or email their results to us, we have been able to keep close tabs on their recovery using the Simple Shoulder Test.The full article was recently published in the JBJS and discussed in this post.


In conclusion, if "value" is defined as the benefit divided by the cost, the SST appears to be a high value assessment tool.