Wednesday, July 18, 2018

Does PRP help patients having rotator cuff repair?

Platelet-rich plasma in fibrin matrix to augment rotator cuff repair: a prospective, single-blinded, randomized study with 2-year follow-up

These authors point out that "despite improvements in the mechanical constructs used to repair rotator cuff tears, retear remains a significant issue. Retear rates ranging from 10%-90% depending on the size of the tear, age of the patient, amount of fatty infiltration, and type of repair have been reported. Higher failure rates in patients older than 65 years have been consistently demonstrated".

They sought to test the concept that application of autologous platelet-rich plasma in fibrin matrix (PRPFM) improves clinical outcomes in patients undergoing arthroscopic rotator cuff repair using a prospective, randomized, single-blinded study of 76 patients. The treatment group underwent arthroscopic rotator cuff repair with PRPFM. 

The control group did not receive the PRPFM. 

The Simple Shoulder Test scores showed no incremental benefit of PPFM: the improvement was from 45% to 96% for the control group and from 49% to 96% in the PRPFM group. 

Strength of the supraspinatus at 24 months by dynamometer testing was 99.8% in the control group and 96.3% in the PRPFM group. Infraspinatus strength was 104% in the control group and 103% in the PRPFM group

MRI's suggested a 19% retear rate for the control group and 7.4% for the PRPFM technique at 6 months.

All of their results showed no statistically significant benefit of PRPFM.

Comment: This is a valuable randomized trial that shows that showed no evidence of added clinical benefit for the PRPFM. If the study had not included the control group, one might conclude that cuff repair with PRPFM argumentation was a "clinically viable technique" because the patients were improved. However, with the inclusion of the control group, it became evident that the addition of PRPFM did not benefit the patients.

It is of interest that in spite of the apparently greater rate of retears in the control group, there was no difference in clinical outcomes.

The authors do not provide the incremental time involvement and the incremental cost of the PRPFM approach (see the details at the end of this post below).

In any event, evidence of incremental value for PRPFM was lacking.

Preparation of PRPFM: "Eighteen milliliters of whole blood was drawn from patients by use of sterile technique, transferred to a specially designed tube for centrifugation in a Drucker 755VES general-purpose centrifuge, 

and spun for 6 minutes at 1100 RPM. During centrifugation, the heavier red and white blood cellular components moved to the bottom of the tube while the lighter platelets remained at the top in the plasma. A polyester separator gel in the tube sealed the red blood cells and the white blood cells to prevent contamination with the platelets. After processing, 4-4.5 cm3 of leukocyte-poor PRP was transferred to 2 separate tubes containing trace amounts of calcium chloride to replace the calcium that was bound by the citrate and was spun for an additional 15 minutes at 1450 RPM. This second, faster spin using the same centrifuge caused the fibrinogen in the plasma to form a 2-cm3 solid PRPFM in disk-like form. The PRPFM was then removed and fashioned on the back table to fit the size and shape of the tear.

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Monday, July 16, 2018

Failed total shoulder: infected?

A patient presented to us one year after having had a left total shoulder using this prosthesis.

The patient experienced pain and stiffness since surgery. The patient has also had chronic swelling and a draining sinus. 

The patient had had two limited I&D's by the original surgeon to drain what was thought to be hematoma. All cultures were negative. The patient  was unable to use the arm for daily activities.
The patient had completed IV antibiotic for a short course of 5 days and an oral course of Keflex and doxycyline. At the time of presentation, the arm had the appearance shown below. CBC, sed rate and CRP were all normal.

And this x-ray showing a fractured central metal peg with surrounding osteolysis. 

We revised this prosthesis by removing all components. The retrieved glenoid showed a fractured peg

The portion of the peg remaining in the glenoid had to be removed with a trephine.

Removal of the humeral component was difficult because of the tight diaphysial fit, the proximal ingrowth surface, and the fragile osteopenic metaphyseal bone.

A cement spacer was inserted with a plan 6 weeks of IV Ceftriaxone followed by oral Augmentin. The pathology report from surgery was as follows: 

Left shoulder capsule, excision: - Fibro-connective tissue with focal fibrin deposition, chronic inflammation, giant cell reaction, and rare neutrophils focally present.  Very few (<5/HPF) neutrophils are identified in one focal area directly underlying surface fibrin deposition. On retrospective review of the frozen section slides, these neutrophils are present, but do not reach numbers above 5/HPF.

At the time of the revision, 8 specimens were submitted for culture. The humeral stem had one colony only of coagulase negative Staph (SpCV 0.1), and one of three capsule specimens grew one colony only of Propionibacterium (SpPV 0.1). The rest showed no growth at 3 weeks.

Four months later, we removed the spacer and inserted a reverse total shoulder. In spite of the glenoid bone deficiency, robust fixation of the baseplate was achieved without bone grafting.

 Comment: When a shoulder arthroplasty fails, we consider
(1) removal/revision of loose components
(2) single stage removal/revision of all components
(3) insertion of an antibiotic spacer, possibly as the first step in a two-stage revision
(4) removal of all components without re-insertion

The decision among these options needs to be based on the information available before and at surgery. Often, as shown in this case, the history, the physical examination, and plain radiographs provide most of the needed information. The results of cultures obtained at the time of revision surgery does not become available in time to inform the surgical decision-making.

This case demonstrates (1) the ever present risk of infection in shoulder arthroplasty, (2) the susceptibility of fatigue fracture of a metal post, (3) the problems created by a tight press-fit bone ingrowth stem should prosthesis removal become necessary.

The potential for fatigue fracture of a hybrid post has been shown in a recent article

Five-year minimum clinical and radiographic outcomes of total shoulder arthroplasty using a hybrid glenoid component with a central porous titanium post.

Here is a radiograph from that article.

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Wednesday, July 11, 2018

Ream and run shoulder arthroplasty - how long will it last?

A 60 year old man presented with pain and loss of function of both shoulders and these x-rays over a decade ago.

Because of his high activity levels and desire to avoid the potential risks and limitations associated with a polyethylene glenoid socket, he elected to have a left ream and run 12 years ago and a right ream and run 10 years ago.

He dropped by the office recently to say hello and to report that he had full function of both of his shoulders.

His 12 and 10 year films are shown below. Note the smooth, thin, impaction-grafted stem on the humeral component and the minimal amount of glenoid reaming without attempt to alter version - just enough to create a single concavity.

While we cannot predict whether or not there will be future problems with these shoulders, it appears that the humeral components and glenoid reaming are well healed without evidence of problems. Note that this is an exceptionally motivated patient who has been absolutely dedicated to his rehabilitation. While all patients do not achieve this quality of result, it seems important to show what can be accomplished.

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Monday, July 9, 2018

Can "biologics" help rotator cuff repairs heal?

Biologic Therapies as Adjunctive Treatments in Rotator Cuff Repair

These authors point out that despite the application of new surgical techniques, failures of cuff repair continue to pose a challenge for orthopaedic surgeons and their patients.

They suggest that a poor biologic environment imay be partly responsible for the inadequate tissue healing associated with rotator cuff tear repairs. This has motivated a search for strategies involving the use of adjunctive biologic therapies, such as platelet-rich plasma (PRP), patches and scaffolds mesenchymal stem cells (MSCs), and cytokines.

However they conclude that the degree of short-term and long-term benefits of these therapies reported in the literature has varied and the indications for use of these approaches have not been established.

This review does not include the costs of these different approaches so it is not possible to determine their incremental value to the patient (i.e. the improvement in clinical outcomes divided by the increase in cost).

Comment: Healing of a failed rotator cuff tendon insertion is a huge challenge. Usually the cuff tear presents with residual tendon that lacks normal quality and quantity. In other words the tissue has less material strength and the normal tendon length is lost. To make matters worse, the cuff tear is bathed in joint fluid containing enzymes that interfere with scar tissue formation, the tendon is relatively avascular, and the loads on the attempted repair are large. And to top it off, the reconstruction of a physiologically and mechanically normal tendon attachment (see below) is highly unlikely in spite of good surgery and whatever biologics may be used. Thus the high rates of failure of cuff repairs are not unexpected.

Assembly, maturation, and degradation of the supraspinatus enthesis

The 4 zones of the normal enthesis: The tendon zone consists of elongated tenocytes. At the border to the fibrocartilaginous zone, the cells change from elongated fibroblasts to round chondrocytes, stacked in columns. The cells enlarge during the transition  from unmineralized to mineralized fibrocartilage. These hypertrophic cells are large cells imbedded in the mineralized matrix, gradually mineralizing the matrix. The mineralized fibrocartilage firmly anchors into the underlying trabecular bone tissue. The tidemark separates the 2 fibrocartilaginous zones.

These authors summarize the current knowledge about development and age-related degradation of the supraspinatus enthesis. Healing and repair of an injured and degenerated supraspinatus enthesis is a challenge, as the original graded transitional tissue of the fibrocartilaginous insertion is not re-created after the tendon is surgically reattached to bone.Instead, mechanically inferior and disorganized tissue forms at the healing site because of scar tissue formation. Consequently, the enthesis never reaches mechanical properties comparable to those of the native enthesis. So far, no novel biologic healing approach has been successful in enhancing healing of the injured enthesis.

Comment: Nature's design for the insertion of the supraspinatus tendon is a marvel of engineering. It provides a smooth mechanical transition from flexible tendon to stiff bone through the intermediate zones of unmineralized and then mineralized fibrocartilage. This structure is analogous to that of a modern electrical plug with transition from the flexible cord to the stiff metal blades.
This graduated transition is designed to prevent the failures associated with a sharp change from flexible to stiff seen in the old plug design.

When we try to repair a rotator cuff detachment, we are taking the degenerated edge of the tendon and attaching it directly to the stiff bone of the tuberosity.

The normal transition through unmineralized and mineralized fibrocartilage is lost and replaced by what the authors call "mechanically inferior and disorganized tissue at the healing site" resulting from scar tissue formation".

Given that we are attempting a repair because of failure of the original tendon insertion to bone, it is not surprising that the inferior tissue at the healing site is at risk for failure as well.

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Scapular notching with the Delta Xtend

Scapular notching refers to the loss of bone from the inferior glenoid neck resulting from contact with the humeral component of a reverse total shoulder.

These authors evaluated patients with preoperative computed tomography (CT) scans who underwent reverse total shoulder with the Delta Xtend; 155 humeral neck-shaft angle and 38-mm [n = 10] or 42-mm [n = 19] glenosphere at a minimum of 2 years of follow-up with video motion analysis (VMA), postoperative threedimensional (3D) CT, and standard radiographs. 

The glenohumeral range of motion demonstrated by the VMA and the postoperative implant location on the CT were used in custom simulation software to determine areas of osseous contact between the humeral implant and the scapula and their relationship to scapular notching on postoperative CT. Patients with and without notching were compared with one another by univariable and multivariable 

Seventeen patients (59%) had scapular notching, which was along the posteroinferior aspect of the scapular neck in all of them and along the anteroinferior aspect of the neck in 3 of them. Osseous contact occurred in external rotation with the arm at the side in 16 of the 17 patients, in internal rotation with the arm at the side in 3, and in adduction in 12. 

Placing the glenosphere in a position that was more inferior (by a mean of 3.4 ± 2.3 mm) or lateral (by a mean of 6.2 ± 1.4 mm) would have avoided most impingement in the patients’ given range of motion. 

Their results suggest that for the Delta Xtend system with its medialized center of rotation, placing the glenosphere in a maximally inferior position while maximizing posterior and lateral placement may help minimize notching.

Comment: While the bony changes of notching can be assessed by x-rays, it is also important to consider changes on the humeral component resulting from the unwanted contact.

Notching can proceed to the point where fixation of the glenoid component is jeopardized.

It is apparent that the design of different prostheses affects the risk of notching. Lateralization of the baseplate can be effective in that regard.
Finally, as a part of the surgical technique with any prosthesis, while the trial components are in place it is important to check for unwanted contact between the humeral component and the scapula with the arm in adduction and in the full range of rotation. If this unwanted contact is present, modification of the prosthesis or its position can be effected.
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Sunday, July 8, 2018

Failed and healed cuff repairs: is there a clinically important difference in outcome?

What Influence Does Progression of a Nonhealing Rotator Cuff Tear Have on Shoulder Pain and Function?

These authors asked (1) Do patients with healed arthroscopic rotator cuff repairs have better outcomes, less pain, and more strength than patients whose repair did not heal? (2) In patients with nonhealed rotator cuff tendons, does tear size progression (increase or decrease) affect outcomes, pain, and strength? (3) Is there continued improvement beyond 6 months in outcomes, pain, and strength; and how do the improvements differ based on whether the tear size has increased or decreased?

They investigated 442 of 647 patients underwent arthroscopic rotator cuff repair for fullthickness tears who had all MRI and clinical information at a minimum of 2 years followup.

Eighty-two of 442 tears (19%) were not healed. The patients with failed repairs were older with a relatively higher percentage of large to massive tears.

Of the nonhealed tears, 45 (55%) had a decrease and 37 (45%) had an increase in tear size. Shoulder function outcomes using the American Shoulder and Elbow Surgeon (ASES) and Constant scores and pain severity using VAS scores were evaluated preoperatively, at 6 months postoperatively, and at the latest followup. Some preoperative (A) and postoperative (B) images are shown below.

Compared with patients with nonhealed tendons after arthroscopic rotator cuff repair, patients with healed repairs had improved ASES scores (healed, 93 ± 5; nonhealed, 89 ± 8; mean difference, 4; 95% CI, 3–5; p< 0.001), better Constant scores (healed, 91 ± 5; nonhealed, 85 ± 8; mean difference, 6; 95% CI, 4–7; p<0.001); however there was no difference in pain level based on VAS scores.

The authors concluded that patients who had healed tendons after arthroscopic rotator cuff repair had better shoulder function than patients who had nonhealed tendons. Among patients with nonhealed rotator cuff tendons after surgery, those with decreased tear size, observed on their 6-month postoperative MRI, compared with their initial tear size, showed better shoulder function and muscle strength than those with increased tear size beyond 6 months.

Comment: It would have been useful to have the preoperative scores for the different patient groups rather than only the postoperative scores so that the reader could compare the amount of improvement and determine the percent of maximum possible improvement for failed and intact repairs. 

For patients having rotator cuff repairs MCID (minimal clinically important difference) for  the ASES score is 12-17 and for the Constant Score is 10. Thus, the patients in this series with intact repairs did not  have clinically significantly better average outcomes than those with failed repairs. 
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Arthritic glenoid anatomy - what information do we need to plan surgery?

A statistical shape model to predict the premorbid glenoid cavity

These authors were interested in inferring the "premorbid" glenoid shape and orientation of scapulae affected by glenohumeral osteoarthritis (OA) to inform restorative surgery.

They used a statistical shape model (SSM) built from 64 healthy scapulae to reconstruct the "premorbid" glenoid shape based on anatomic features that are considered unaffected by OA. First, the method was validated on healthy scapulae by quantifying the accuracy of the predicted shape in terms of surface distance, glenoid version, and inclination. 

The SSM-based reconstruction was then applied to 30 OA scapulae. Glenoid version and inclination were measured fully automatically and compared between the original OA glenoids, SSM-based glenoid reconstructions, and healthy scapulae.

Validation on healthy scapulae showed a root-mean-square surface distance between original and predicted glenoids of 1.0 ± 0.2 mm. The prediction error was 2.3° ± 1.8° for glenoid version and 2.1° ± 2.0° for inclination. In other words the model based on healthy scapulae can predict the glenoid position in healthy scapulae.

When applied to an OA dataset, SSM-based reconstruction "restored" average glenoid version and inclination to values similar to the healthy situation. 

The authors concluded that the SSM can predict the "premorbid" glenoid cavity of healthy scapulae with millimeter accuracy. They claim that this technique has the potential to reconstruct the "premorbid glenoid cavity shape, as it was prior to OA, and thus to guide the positioning of glenoid implants in total shoulder arthroplasty."

Comment: While this is an interesting methodology, it may not be completely accurate to state that the model recreates "premorbid" anatomy; for patients with OA we cannot assume that their anatomy was "normal" prior to the development of arthritis. For example, increased "premorbid" retroversion may predispose the shoulder to arthritis.

Secondly (see below) the average deviation of the arthritic anatomy from "normal" is small (6 degrees or less) and the variation among subjects is in many cases greater than the mean value. Are the differences among glenoid types clinically significant?

Thirdly, one must be cautious about suggesting that such measurements should "guide the positioning of glenoid implants in total shoulder arthroplasty." Take for example the B3 glenoid that had 22 degrees of retroversion, yet, by definition, had the humeral head centered in the glenoid (see below)

Is it reasonable to suggest that the glenoid version should be "corrected" by 22 degrees? If so, by what means, anterior reaming, bone graft, posteriorly augmented glenoid component, or reverse total shoulder?

Fourthly, what is the added cost and time necessary to perform this type of modeling in comparison to obtaining a standardized axillary view (see this link). For which patients would this technology be cost-effective?

Finally, how important is "correction" of glenoid version? See the abstract below which addresses the question, Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

Background: While glenoid retroversion and posterior humeral head decentering are common preoperative features of severely arthritic glenohumeral joints, the relationship of postoperative glenoid component retroversion to the clinical results of total shoulder arthroplasty (TSA) is unclear. Studies have indicated concern for inferior outcomes when glenoid components are inserted in 15° or more retroversion.
Questions/Purposes: In a population of patients undergoing TSA in whom no specific efforts were made to change the version of the glenoid, we asked whether at 2 years after surgery patients having glenoid components implanted in 15° or greater retroversion had (1) less improvement in the Simple Shoulder Test (SST) score and lower SST scores; (2) higher percentages of central peg lucency, higher Lazarus radiolucency grades, higher mean percentages of posterior decentering, and more frequent central peg perforation; or (3) a greater percentage having revision for glenoid component failure compared with patients with glenoid components implanted in less than 15° retroversion. 
Methods: Between August 24, 2010 and October 22, 2013, information for 201 TSAs performed using a standard all-polyethylene pegged glenoid component were entered in a longitudinally maintained database. Of these, 171 (85%) patients had SST scores preoperatively and between 18 and 36 months after surgery. Ninety-three of these patients had preoperative radiographs in the database and immediate postoperative radiographs and postoperative radiographs taken in a range of 18 to 30 months after surgery. Twenty-two patients had radiographs that were inadequate for measurement at the preoperative, immediate postoperative, or latest followup time so that they could not be included. These excluded patients did not have substantially different mean age, sex distribution, time of followup, distribution of diagnoses, American Society of Anesthesiologists class, alcohol use, smoking history, BMI, or history of prior surgery from those included in the analysis. Preoperative retroversion measurements were available for 11 (11 shoulders) of the 22 excluded patients. For these 11 shoulders, the mean (± SD) retroversion was 15.8° ± 14.6°, five had less than 15°, and six had more than 15° retroversion. We analyzed the remaining 71 TSAs, comparing the 21 in which the glenoid component was implanted in 15° or greater retroversion (mean ± SD, 20.7° ± 5.3°) with the 50 in which it was implanted in less than 15° retroversion (mean ± SD, 5.7° ± 6.9°). At the 2-year followup (mean ± SD, 2.5 ± 0.6 years; range, 18–36 months), we determined the latest SST scores and preoperative to postoperative improvement in SST scores, the percentage of maximal possible improvement, glenoid component radiolucencies, posterior humeral head decentering, and percentages of shoulders having revision surgery. Radiographic measurements were performed by three orthopaedic surgeons who were not involved in the care of these patients. The primary study endpoint was the preoperative to postoperative improvement in the SST score. 
Results: With the numbers available, the mean (± SD) improvement in the SST (6.7 ± 3.6; from 2.6 ± 2.6 to 9.3 ± 2.9) for the retroverted group was not inferior to that for the nonretroverted group (5.8 ± 3.6; from 3.7 ± 2.5 to 9.4 ± 3.0). The mean difference in improvement between the two groups was 0.9 (95% CI, − 2.5 to 0.7; p = 0.412). The percent of maximal possible improvement (%MPI) for the retroverted glenoids (70% ± 31%) was not inferior to that for the nonretroverted glenoids (67% ± 44%). The mean difference between the two groups was 3% (95% CI, − 18% to 12%; p = 0.857). The 2-year SST scores for the retroverted (9.3 ± 2.9) and the nonretroverted glenoid groups (9.4 ± 3.0) were similar (mean difference, 0.2; 95% CI, − 1.1 to 1.4; p = 0.697). No patient in either group reported symptoms of subluxation or dislocation. With the numbers available, the radiographic results for the retroverted glenoid group were similar to those for the nonretroverted group with respect to central peg lucency (four of 21 [19%] versus six of 50 [12%]; p = 0.436; odds ratio, 1.7; 95% CI, 0.4–6.9), average Lazarus radiolucency scores (0.5 versus 0.7, Mann-Whitney U p value = 0.873; Wilcoxon rank sum test W = 512, p value = 0.836), and the mean percentage of posterior humeral head decentering (3.4% ± 5.5% versus 1.6% ± 6.0%; p = 0.223). With the numbers available, the percentage of patients with retroverted glenoids undergoing revision (0 of 21 [0%]) was not inferior to the percentage of those with nonretroverted glenoids (three of 50; [6%]; p = 0.251). 
Conclusion: In this small series of TSAs, postoperative glenoid retroversion was not associated with inferior clinical results at 2 years after surgery. This suggests that it may be possible to effectively manage arthritic glenohumeral joints without specific attempts to modify glenoid version. Larger, longer-term studies will be necessary to further explore the results of this approach.

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