Wednesday, August 9, 2017

Which patients with shoulder arthritis are likely to benefit from Interpositional human dermal allograft?

Arthroscopic Joint Preservation in Severe Glenohumeral Arthritis Using Interpositional Human Dermal Allograft

These authors reported results of arthroscopic glenoid resurfacing for glenohumeral arthritis at an average of 60 month clinical followup or until revision. Patients lost to follow-up and those included in a prior study were excluded.

The visual analog scale pain score improved from a median of 7 to 2. Median ASES score improved from 47 to 76; active forward elevation improved from 110 to 140.

The rate of revision to prosthetic arthroplasty was 23% after a mean of 45 months. The mean age of revised shoulders (60 years) was higher than that of surviving shoulders (53 years). The preoperative ASES score of revised shoulders (34) was lower than that of surviving shoulders (47). 
Revisions included hemiarthroplasty in 3 shoulders, anatomic total shoulder arthroplasty in 4, and reverse total shoulder arthroplasty in 3.

With multivariate analysis, exact odds ratios for age and preoperative ASES score as risk factors for revision were 1.3 (95% CI, 1.0-1.6; P . .02) and 0.9 (95% CI, 0.8-1.0; P . .003), respectively.

Comment: In considering the appropriate use for this procedure, it would be of interest to know the effect of glenoid type (e.g. A2 vs B2), sex, and prior surgery on the outcomes. It would also be of interest to know the relationship of radiographic joint space at followup to the clinical outcome. Finally, it would be of interest to know the outcomes of revisions: were they comparable to the results that would have been expected if the arthroplasty was performed primarily, or were the results inferior when performed as a revision?

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Tuesday, August 8, 2017

The table slide - the key to gaining motion after the ream and run

Our favorite shoulder therapist says, 'motion is lotion'. Some of our joint replacement surgeries require lots of lotion. 
One of our recent patients (a martial artist in his mid fifties) schooled us on the table slide exercise. Here he is demonstrating four weeks after his ream and run.

video
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Is humeral resurfacing a conservative treatment for primary arthritis?

Outcome and revision rate of uncemented glenohumeral resurfacing (C.A.P.) after 5–8 years

These authors report the mid-term results of an uncemented resurfacing shoulder prosthesis in patients with primary osteoarthritis having surgery from January 2007 to December 2009. No glenoid arthroplasty was used in these patients.

Forty-six patients (12 males) with a mean age of 72 years old (range 59–89) were included. At a mean 6.4-year follow-up (range 5–8), the Constant Score, visual analog pain scale and the Dutch Simple Shoulder Test scores improved significantly (p < 0.05) from baseline.

 Eleven patients (23%) had a revision operation.


They compared their revision rate to that in prior publications
Comment: We're often asked whether a resurfacing hemiarthroplasty is a conservative option for the management of glenohumeral arthritis. As demonstrated by this study, the issue with the resurfacing hemiarthroplasty appears to be the fact that it does not address the glenoid aspect of glenohumeral arthritis. These authors did not seem to have problems with fixation of the humeral component, but rather most of the problems related to glenoid erosion.
While it may seem simple to combine a resurfacing with a glenoid component, experience has shown that the retention of the humeral anatomic neck can interfere with good access to the glenoid, compromising the ability to perform a technically excellent prosthetic glenoid arthroplasty.
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Stemless humeral components - do they solve a problem? (Part 2)

Is the stemless humeral head replacement clinically and radiographically a secure equivalent to standard stem humeral head replacement in the long-term follow-up? A prospective randomized trial

These authors used a stemless humeral component in 20 patients (Group 1) and a stemmed design in 20 patients (Group 2).


Twenty-nine patients were examined clinically and radiographically at a minimum follow-up of 2 years and a minimum follow-up of 5 years.

The postoperative CS improved significantly in both groups, with no significant difference between the minimum of 2-year and 5-year follow-up. There were no significant differences in final Constant score or range of motion between the two groups. However, the patients receiving the stemmed design (Group 2) had substantially lower preoperative Constant scores and poorer range of motion:






Thus the amount of improvement at two years in the relative Constant score was 12.9 for the stemless and 55.7 for the stemmed component.  The amount of improvement at two years in flexion was 19.3 degrees for the stemless and 47.4 degrees for the stemmed component.

With this particular stemmed implant there was lower bone density adjacent to the humeral calcar in 41% and there were significantly more frequent radiolucent lines.  No diminished density was seen with this stemless particular stemless implant. However, the group receiving the stemmed implant were older and had a higher percentage of females, both of which factors may have contributed to the radiographic findings.

No complication concerning the humeral implant was observed in group 1 (stemless). For the glenoid implant, atraumatic loosening of the glenoid component was noted in 2 patients, which led to a revision and exchange of the glenoid component. One rotator cuff deficiency, which led to a revision with conversion to a reverse prosthesis, was observed. 

In group 2 (stemmed), a fracture of the greater tuberosity resulted in 1 traumatic loosening of the humeral implant. There were no complications at the glenoid implant in group 2.

Comment: In this comparative series, patients in the stemless group appear to have realized less functional improvement and experienced a higher complication rate than those in the stemmed group.
We continue to use impaction grafting of a relatively thin smooth humeral stem because of the simplicity of use, the maximal bone preservation, the broad load distribution that minimizes stress shielding and the ease of revision, should that ever become necessary. 

Note in these two year followup films the preservation of the humeral bone stock, the stable fixation of the long stem achieved with impaction autografting, and the absence of stress shielding/bone resorption.
Note also the absence of radiolucent lines around the all polyethylene glenoid component, the absence of cement on the back side of the glenoid component, and the bone ingrowth between the flanges of the central peg of the glenoid component (arrow). 

On the postoperative 'truth' axillary view, note again the bone ingrowth, the absence of back side cement, and the absence of radiolucent lines as well as the centering of the humeral head in the glenoid and the preservation of glenoid bone stock.

This technique provides a dependable, adaptable and bone-preserving approach to total shoulder arthroplasty.


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Stemless humeral components - do they solve a problem?

Stemless Shoulder Arthroplasty: Review of Early Clinical and Radiographic Results

Implant company interest in stemless devices has led to a plethora of designs, each with its particular features, challenges, and learning curve.



 

 

 

These authors review the potential issues with stemless humeral components, including implant fixation, stress shielding, subscapularis management, periprosthetic fracture, and the learning curve.

The interested reader may like to review the following study:

Clinical and Radiographic Outcomes of the Simpliciti Canal-Sparing Shoulder Arthroplasty System: A Prospective Two-Year Multicenter Study.

These authors report the minimum two year followup on 149 of 157 patients with glenohumeral arthritis from 14 different centers treated with a press-fit, porous-coated, metaphyseal fixed humeral implant between July 2011 and November 2012 in a U.S. Food and Drug Administration (FDA) Investigational Device Exemption (IDE)-approved protocol.

The mean age and sex-adjusted Constant, SST, and ASES scores improved from 56% preoperatively to 104% at two years (p < 0.0001), from 4 points preoperatively to 11 points at two years (p < 0.0001), and from 38 points preoperatively to 92 points at two years (p < 0.0001), respectively. 

The mean forward elevation improved from 103° ± 27° to 147° ± 24° (p < 0.0001) and the mean external rotation, from 31° ± 20° to 56° ± 15° (p < 0.0001). The mean strength in elevation, as recorded with a dynamometer, improved from 12.5 to 15.7 lb (5.7 to 7.1 kg) (p < 0.0001), and the mean pain level, as measured with a visual analog scale, decreased from 5.9 to 0.5 (p < 0.0001). 

There were three postoperative complications that resulted in revision surgery: infection, glenoid component loosening, and failure of a subscapularis repair. There was no evidence of migration, subsidence, osteolysis, or loosening of the humeral components or surviving glenoid components.

Comment: These authors are to be congratulated on a well-done prospective FDA approved multicenter trial with 16 shoulder reconstruction specialists to investigate the new device. See this link. In the hands of these surgeons and in these patients the device demonstrated safety and efficacy.

They point out that humeral complications in shoulders with stemmed humeral components are rare, but can include periprosthetic humeral fractures during and following total shoulder arthroplasty, proximal humeral bone loss due to stress shielding, humeral stem loosening, and osteolysis. They also point out that removal of a well-fixed humeral stem can be difficult and can result in additional destruction of proximal humeral bone. They assert that a stemless humeral component could provide a method for (1) making revision easier by preservation of the humeral bone and (2) improving anatomic positioning of the humeral head; however neither of these assertions is tested in this paper. It is not known whether this approach saves operating time or has a lower cost in comparison to standard humeral implants.

It is of note that the application of the the stemless implant was limited; it was used for less than 1/3 (31.4% (157)) of the 500 primary anatomic total shoulder arthroplasties performed by the study surgeons during the enrollment period. Reasons for non-use were many: low preoperative Constant score, diagnoses other than osteoarthritis or posttraumatic arthritis, patients with risk of falls, prior open surgery, cortisone use, physical activities that could affect the outcome of surgery, or lack of sufficient quality bone to seat and support implant (the surgeon attempted to compress the neck cut surface with his/her thumb; bone that was easily compressed with minimal force was considered insufficient for implantation of this device).

In contrast to this stemless device, we find that an impaction-grafted humeral component not only preserves but adds bone to the humerus, enables positioning of the humeral articular surface in the desired location (including an eccentric offset when needed as shown in this link) and is applicable to essentially the full range of shoulder arthroplasty indications, rather than being subject to the restrictions for a stemless prosthesis described in this article.


We use a chrome cobalt humeral head prosthesis connected to a stem (titanium alloy) the tapered body of which fits inside the humerus.

We note that the humeral canal may be cylindrical or tapered.
and that the cross sectional geometry varies 

We agree that trying to fit a prosthesis by reaming the inside of the bone may substantially weaken it.

and that trying to force a tight fit risks fracture.

Our preferred method for securing the stem within the humeral canal is to use impaction grafting with bone harvested from the arthritic humeral head to conform the inner surface of the bone to the prosthesis. Some have likened this fitting of the patient's bone the prosthesis to the fitting of the traveler to the bed by the inn keeper Procrustes.
As a result, the tapered stem is securely fixed with a biological press fit that safely distributes the load from the prosthesis to the humerus, avoiding stress shielding which has been noted with short stem prostheses (see this link).

The amount of bone removed with an impaction grafted stem (below left) seems no greater than that with a stemless head prosthesis (below right).

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Monday, August 7, 2017

Propionibacterium - not only acnes, not only in the shoulder

Propionibacterium avidum – a virulent pathogen causing hip periprosthetic joint infection

These authors report four hip prosthetic joint infections caused by P. avidum in one orthopedic center in 2015. They also characterized the hemolytic and biofilm-producing capacity of the four clinical P. avidum strains and investigated their phylogenetic relationships by whole genome sequencing. On searching their records from 1997 to 2015 they  retrospectively identified 13 P. avidum PJIs, with the majority being hip-related infections (n=11).

Preoperative synovial fluid cultures were P. avidum positive in 63.6% of cases. Six out of 12 patients (50%) with available case histories were treated with an exchange of the prosthesis. In all but one of the six patients treated with debridement-retention of the prosthesis, treatment failed thus requiring a two-stage revision. 

The isolated P. avidum strains showed a more pronounced hemolytic activity, but a similar biofilm-forming ability when compared to P. acnes.


 Whole genome sequencing identified two phylogenetic clusters highly related to P. avidum PJI strains isolated in Sweden.

Comment: As we become more accurate and precise in our characterization of Propionibacterium recovered from prosthetic joint infections, it is important to recognize that P. Acnes is not the only species of clinical importance as is pointed out in this article and in these links: Propionibacterium – What we think we know today and Genome Sequence of a Novel Species, Propionibacterium humerusii.  As is true for other bacterial species, it is reasonable to expect that these other species (P. avidum, P. granulosum, P. humerusii, and perhaps others) may have different clinical features and different antibiotic sensitivities from P. acnes. We need to ask our laboratories to put forth the additional effort to speciate Propionibacterium, rather than reporting them all as "P. acnes".  As shoulder surgeons, we need to share these insights with our hip, knee and spine colleagues in that they are likely to encounter these organisms as well.

The retrospective nature of this study is very likely to underestimate the incidence of Propionibacterium in the arthroplasty revisions because 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 (see Origin of propionibacterium in surgical wounds and evidence-based approach for culturing propionibacterium from surgical sites).

This study does not present the data on revised joints that were culture positive for P. acnes or other Propionibacterium species during the same time interval.

Finally, this study points out that complete prothesis exchange may be necessary to resolve Propionibacterium infections.


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Total shoulder - a conservative, bone-preserving approach

Two years ago a woman in her late 50's presented with pain in the right shoulder, an SST score of 5 out of 12, and these x-rays: 
Note the hooking osteophyte and the lack of joint space on the AP view

And the glenoid retroversion, biconcavity and posterior decentering on the the axillary 'truth' view.

She returned for her two year followup with an SST score of 12 out of 12 and these x-rays:

Note the preservation of the humeral bone stock, the stable fixation of the long stem achieved with impaction autografting, and the absence of stress shielding/bone resorption.
Note also the absence of radiolucent lines around the glenoid component, the absence of cement on the back side of the glenoid component, and the bone ingrowth between the flanges of the central peg of the glenoid component (arrow).

On the postoperative 'truth' axillary view, note again the bone ingrowth, the absence of back side cement, and the absence of radiolucent lines as well as the centering of the humeral head in the glenoid and the preservation of glenoid bone stock.

This technique provides a dependable, adaptable and bone-preserving approach to total shoulder arthroplasty.


===
The reader may also be interested in these posts:





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'