Effect of immobilization on the tendon - bone interface

The Effect of Immobilization on the Native and Repaired Tendon-to-Bone Interface

To set the stage for our review of this article, here's a picture of a device marketed as a 'shoulder immobilizer'.

This is a carefully done study the goal of which was to examine the effects of immobilization on a rat tendon-bone junction. The rat knee joint was immobilized at 90 degrees using an external skeletal fixator, the exact stiffness of which is not specified.   The tendon-bone insertion site was evaluated after immobilization with use of histologic, radiographic, and biomechanical analyses. Immobilization led to a significant decrease in the load to failure and stiffness compared with the native tendon at both two and four weeks. The authors also note that immobilized repaired tendons had better mechanical properties than immobilized intact tendons at one month (but were less strong than native, non-immobilized tendon). The protocol did not include non-immobilized repaired tendons.

Comment: The effects of rigid immobilization on the intact tendon-bone complex were significant. It is difficult to know the mechanism for this effect: is it the lack of motion or a change in loading or both? While the authors caution: "Surgeons who manage patients with immobilization should be aware of the changes at the bone-tendon complex," it is unusual for surgeons to immobilize joints rigidly with a spanning external fixator as was done here. We suggest that 'immoblization' is not a defined state, but rather a relative concept. A sling, as often used after a rotator cuff repair, or a brace, often used after a knee ligament repair, does not completely immobilize the joint nor does it protect the tendon-bone complex from loading. 

There can be no question that the mechanical environment of connective tissue can have profound effects on its material and structural properties as well as on the healing and remodeling of surgical repair. A better understanding of these effects will help inform the way we manage conditions affecting the attachment of tendon to bone.

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Cuff tear arthropathy: CTA prosthesis or reverse total shoulder

Comparison of Functional Outcomes of Reverse Shoulder Arthroplasty with Those of Hemiarthroplasty in the Treatment of Cuff-Tear Arthropathy: A Matched-Pair Analysis

This is the preoperative x-ray of a 70+ year old avid skier, rock climber when we first saw him in a year and a half ago. He could perform only 5 of the 12 functions of the simple shoulder test. After we presented him with the pros and cons of a CTA arthroplasty and a reverse total shoulder, he chose the former because of his desire to continue to ski and climb.

Here is his x-ray from today

He stated he has been having no pain in his operated shoulder and has been actively pursuing his sports without problem and without pain. He has improved from 5/12 simple shoulder test functions to 12/12. He presented today because he wanted the same procedure performed on his right shoulder.

We present this case before starting our discussion of the paper above to emphasize that the decision between a CTA prosthesis and a reverse total shoulder is not made on 'which is better?', but rather 'which is better for the given shoulder in the individual patient?'


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The authors compared the results of 102 primary hemiarthroplasties for rotator cuff-tear arthropathy were compared with those of 102 reverse shoulder arthroplasties identified from the New Zealand Joint Registry. The patients were matched for age, sex, and American Society of Anesthesiologists (ASA) scores. Oxford Shoulder Scores (OSS) collected at six months postoperatively as well as mortality and revision rates were compared between the two groups. Unfortunately the preoperative OSS scores were not available, so that the improvement from the two surgeries cannot be known. Furthermore, data on prior surgeries, the status of the coracoacromial arch and residual rotator cuff are lacking.

There were fifty-one men and fifty-one women in each group, with a mean age of 71.6 years in the hemiarthroplasty group and 72.6 years in the reverse shoulder arthroplasty group. One third and one fourth of the patients did not participate in the followup, respectively. The mean OSS at six months was 31.1 in the hemiarthroplasty group and 37.5 in the reverse shoulder arthroplasty group. 

No difference was seen in early revision rates, with four revisions performed in each group within twelve months after the surgery. At the time of follow-up, there had been nine revisions in the hemiarthroplasty group and five in the reverse shoulder arthroplasty group. However, the lengths of follow-up were different (6.8 years for the CTA and 4.8 for the reverse total shoulders. Thus the annualized rates of revision were 1% per year for both types of prostheses.  In the hemiarthroplasty group, two patients underwent a revision because of infection; one, because of dislocation; and six patients had a revision to a reverse shoulder arthroplasty because of ongoing pain. In the reverse shoulder arthroplasty group, two patients had a revision because of infection; two, because of glenoid component loosening; and one, because of dislocation.

While the authors conclude that "reverse shoulder arthroplasty resulted in a functional outcome that was superior to that of hemiarthroplasty", the difference is small. The choice between these two procedures needs to be individualized based on patient specifics, such as the preoperative comfort and function, the desired postoperative activity level, the status of the coracoacromial arch, the presence or absence of anterosuperior escape, the presence or absence of pseudo paralysis, the bone quality, the glenohumeral anatomy, and the risk of falling. The diagnostic term 'cuff tear arthropathy' offers insufficient information on which the choice of procedures can be based. In our practice a shoulder with cuff tear arthropathy and pseudoparalysis and anterosuperior escape would not be an optimal candidate for a CTA prosthesis; a shoulder in a physically active person with cuff tear arthropathy and an intact coracoacromial arch without pseudoparalysis, would not be an optimal candidate for a reverse total shoulder.

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What activities have people done after a ream and run for shoulder arthritis??

The ream and run is not for every surgeon and not for every patient with shoulder arthritis. Having said that, we frequently get reports of high levels of function after this procedure. The six minute video shown here is a rough compilation of some of the many .mpegs, .movs, and .avi's we've been sent by individuals from across the U.S. after having had a ream and run on one or both shoulders. Each of these individuals worked very hard on their rehab and deserve most of the credit for the success of their surgery. This video does not show average folks doing average things; it shows extraordinary folks doing extraordinary things.

Video.

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Glenoid component failure, osteolysis - sterilized by radiation in air

We had an interesting day yesterday in the OR. Among other revisions, smooth and moves, and ream and runs, we revised two Tornier total shoulders. The first case had already had a revision (elsewhere) of a Tornier total shoulder on the left shoulder for a failed glenoid. The right arthroplasty had been done in 2005. In 10/2012 we saw him for the first time because of pain in the right shoulder. His x-ray is shown below, revealing glenoid osteolysis.

In 5/2013 he decided to proceed with revision. At that time his films showed a dramatic increase in the osteolysis as well as evidence of a shift in the position of the glenoid component markers.

At surgery his component was loose and worn.

There was no obvious evidence of infection, but the shoulder was filled with non-inflammatory reactive tissue, such as the below.

We obtained multiple cultures for Propionibacterium and other bacteria before administering Ceftriaxone and Vancomycin (which we will continue for 6 weeks followed by a year of oral antibiotics).

After a thorough cleanout, we reconstructed his shoulder using a press fit humeral prosthesis that articulated with the rim of his residual glenoid. No glenoid bone graft was used. Post op we are starting him on our routine post-arthroplasty rehabilitation.

The second case had a Tornier total shoulder implanted in 2000. At the time of presentation to us, the radiographs, like the first case, showed massive osteolysis and glenoid component loosening.

The operative findings and the procedure were identical to the prior case. The postoperative films are shown here.

Comment: the surgical findings in these cases are consistent with either a Propionibacterium infection or with 'polyethylene disease' resulting from particles of poly released into the shoulder by component wear. Each of these glenoid components were not only loose, but the poly was degenerated suggesting that they may have been sterilized by gamma radiation in air. This is a problem previously noted in DePuy glenoids as well when the component was sterilized in air. The only way to distinguish them is by cultures of multiple samples (at least 5) of tissue and explants, holding them for three weeks and using multiple culture media.  For that reason we have both of these patients on the 'red' protocol of IV antibiotics via a PICC line for six weeks. If cultures are negative, we will discontinue antibiotics afterwards. Otherwise the patients will be on oral antibiotics for a year.

The humeral head prostheses have the largest diameter so that they will sit on the rim of the osteolytic glenoid. No glenoid bone grafting is used, but Vancomycin / allograft is used for humeral component fixation.

The histology on such cases usually looks like that shown below

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Attaching the rotator cuff to bone, how does nature do it?

The attachment of a tendon to bone is called an enthesis. Here is a picture of the cuff insertion to bone in an animal a presented at the most recent Orthopaedic Research Society meeting.

We can see the zones that are so critical to managing the bending and twisting loads that are applied to the junction of flexible tendon to inflexible bone. At upper right we can see the wavy tendon fibers. At lower left we can see the solid bone. Between, stained in green, is fibrocartilage - more flexible than bone, less flexible than tendon. Nearer the bone, the fibrocartilage is calcified and nearer the tendon the fibrocartilage transitions to tendon fibers. 

This arrangement is similar to that of a modern electrical plug (see below), which has to manage the mechanical transition between the flexible wire and the rigid body of a laptop. As in the case of the normal cuff enthesis, this is accomplished by a transition zone from more flexible on the right to less flexible on the left.

When this progressive transition is lacking, the attachment is at risk for failure at the junction of the flexible to the stiff. This is, of course, where rotator cuff defects occur.

A couple of lessons may be derived from this observation:

(1) Maintaining shoulder flexibility through gentle stretching may help reduce the risk of rotator cuff failure.

(2) Surgical repairs of the rotator cuff do not, of themselves, restore this transition. 

Rather, the re-establishment of the transition zone is accomplished by progressive remodeling over time. Until the transition zone is re-established, we can suspect that the cuff repair is vulnerable to failure.

Some of the readers may remember the old-style electrical plug without the transition zone. It's easy to guess where the failure occurred.

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When to repair the rotator cuff - well known surgeons disagree

In April 2013 the 12th International Congress of Shoulder and Elbow Surgery took place in Nagoya, Japan.

This meeting gathered well known surgeons from around the world. We were especially interested in the recommendations for treatment of rotator cuff defects. Two highly respected surgeons each presented their thoughts.

Christian Gerber from Zurich presented the Neer Lecture on Rotator Cuff Tendon Tears. We quote here from his abstract in the Congress Program: "Surgical repair of small, non-retracted tears yields excellent and durable results, which, however, have not been proven to be superior to subacromial debridement, biceps tenotomy or even the natural history [i.e. non surgical management]. There are no cost-effectiveness studies indicating that small tears justify operative intervention. Surgical treatment of disabling large tears, however, has proven to improve quality of life, pain, function and work capacity relatively reliably and durably."

Ken Yamaguchi from St. Louis presented an instructional course lecture on Natural History of Rotator Cuff Tears: Implications for Treatment. We quote here from his abstract in the Congress Program: “Early surgery is recommended for rotator cuff tears in younger patients (less than 60 years old), patients with small to medium sized tears, especially if the anterior supraspinatus is intact and thus, at risk for rupturing, large, degenerative partial tears, acute tears of any size, new or sudden pain in any risk age group, and tears that are bordering on 1.5 cm of transverse dimension. Patients with chronic large tears or elderly patients, greater than the age of 65 are much better candidates for conservative [i.e. non surgical] management." 

Our approach is rather simple as explained in this patient handout. As repeated observed in this blog, repairs of large atraumatic tears often do not hold up and may not merit the cost and downtime associated with a surgical repair. We have been impressed by the results of the 'smooth and move' procedure when such cuff defects do not respond to gentle stretching and strengthening exercises.

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Rotator cuff repair: integrity and functional outcomes (guess what?)

Repair integrity and functional outcomes for arthroscopic margin convergence of rotator cuff tears.

The authors studied 24 consecutive patients with full-thickness rotator cuff tears, in which the free tendon edge could not be reduced to the footprint after the release and mobilization of the rotator cuff tendon. Rotator cuff repair integrity was determined by magnetic resonance imaging or ultrasonography after the operation. The mean age and follow-up period for the patients were 60 years and 31 months.

Half of the repairs were found to be retorn at followup. While the clinical outcomes were improved for the entire group, the VAS, ASES, UCLA and Constant scores were not different between the healed and the unhealed shoulders. 

The authors make the somewhat quizzical statement: "Although the functional scores were not significantly different between the healed and unhealed groups after margin convergence, it does not mean that margin convergence would be better than not fully reducing the cuff or not repairing the cuff at all."

It would have been informative had the authors analyzed the effects of age and tear size on the functional result.

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