Tuesday, January 27, 2015

The ream and run: not for every patient, every surgeon or every problem


The ream and run: not for every patient, every surgeon or every problem

This article was invited by International Orthopaedics. The abstract is reproduced here.


The purpose of this paper is to provide some essential and basic information concerning the ream and run technique for shoulder arthroplasty.

In a total shoulder arthroplasty, the humeral head prosthesis articulates with a polyethylene glenoid surface placed on the bone of the glenoid. Failure of the glenoid component is recognised as the principal cause of failure of total shoulder arthroplasty. By contrast, in the ream and run procedure, the humeral head prosthesis articulates directly with the glenoid, which has been conservatively reamed to provide a stabilising concavity and maximal glenohumeral contact area for load transfer. While no interpositional material is placed on the surface of the glenoid, animal studies have demonstrated that the reamed glenoid bone forms fibrocartilage, which is firmly fixed to the reamed bony surface. Glenohumeral motion is instituted on the day of surgery and continued daily after surgery to mold the regenerating glenoid fibrocartilage. When the healing process is complete - as indicated by a good and comfortable range of motion - exercises and activities are added progressively without concern for glenoid component failure. 

The experience to date indicates that a technically well done ream and run procedure can restore high levels of comfort and function to carefully selected patients with osteoarthritis, capsulorrhaphy arthroplathy, and posttraumatic arthritis.

Patients considering the ream and run procedure should understand that this technique avoids the risks and limitations associated with a polyethylene glenoid component, but that it requires strong motivation to follow through on a rehabilitation course that may require many months. The outcome of this procedure depends on the body’s regeneration of a new surface for the glenoid and requires rigorous adherence to a daily exercise program. This paper explains in detail the principal factors in patient selection and the key technical elements of the procedure. Clinical examples and outcomes are demonstrated.

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Thursday, January 22, 2015

Degenerative rotator cuff tears continue to degenerate over time.

A Prospective Evaluation of Survivorship of Asymptomatic Degenerative Rotator Cuff Tears

These authors conducted a prospective study of patients with an asymptomatic rotator cuff tear in one shoulder and pain due to rotator cuff disease in the contralateral shoulder. Initially there were 118 full-thickness tears, fifty-six partial-thickness tears, and fifty were intact. These shoulders were followed for a median of 5.1 years.

Half of the shoulders demonstrated tear enlargement with a median time to enlargement of 2.8 years.

Over 25% of the 50 intact shoulders progressed to cuff tears (9 to partial thickness and 5 to full thickness tears). Almost 20% of the 56 partial thickness tears progressed to full thickness tears.

Tear-enlargement rates were 61% in the full-thickness-tear group, 44% in the partial thickness-
tear group, and 14% in the control group.
Tear enlargement was associated with the onset of new pain.

Supraspinatus and infraspinatus muscle degeneration increased significantly more in shoulders with tear enlargement than in the shoulders with stable tears.

Comment: This study demonstrates that degenerative rotator cuff tears continue to progress with time. Shoulders with bigger tears are more likely to demonstrate tear progression.

While the authors state that such natural history studies "allow better assessment of the appropriate timing of intervention and identification of specific at-risk groups in which early intervention may be most beneficial," the indications for surgical repair of degenerative tears have yet to be clarified as shown here. The observation that large full-thickness tears are likely to progress over time cannot be taken as evidence that attempting a surgical repair of these tears will restore the integrity of the cuff or prevent degeneration of the associated muscle.

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Tuesday, January 20, 2015

Resurfacing hemi and total shoulder arthroplasty in young patients


Surface replacement arthroplasty for glenohumeral arthropathy in patients aged younger than fifty years: results after a minimum ten-year follow-up

These authors present a case series of 54 cementless surface replacement arthroplasties (49 patients (25 men, 24 women)(average age 38.9 years (range, 22-50 years)) performed between 1990 and 2003. Of these, 38 patients (42 shoulders) were available for followup at a mean of 14.5 years (range, 10-25 years) after surgery.
17 were total shoulder replacements with metal back keeled glenoids, and 37 were humeral head resurfacing with microfracture of the glenoid.

It is of note that the diagnoses in this report from the UK were as follows:

avascular necrosis, 16
rheumatoid arthritis, 20
instability arthropathy, 7
primary osteoarthritis, 5
fracture sequelae, 3
postinfection arthritis, 2
psoriatic arthritis, 1

These are different from the usual indications for shoulder arthroplasty in the U.S., where primary osteoarthritis dominates, although the diagnostic spectrum is different in younger individuals even on this side of the pond.

17 cases had full thickness cuff tears or poor quality rotator cuffs.

The deltopectoral approach was used in 20 shoulders and the  anterosuperior (Neviaser-Mackenzie) approach in 34. The anterosuperior approach became the preferred approach in1993.

The mean relative Constant score increased from 11.5% to 71.8%, the results with humeral head resurfacing with microfracture of the glenoid (77.7%) were superior to those with total resurfacing arthroplasty that included a glenoid component (58.1%). 

The best results were observed for the AVN patients, with Constant score improving from 13%  to 85%. These were followed by the primary osteoarthritis group results and the rheumatoid arthritis group which had more modest results but high levels of satisfaction.

In 35 of 38 shoulders the humeral implants showed no lucencies. All of the humeral lucencies were observed in cases having a glenoid component. There were 9 glenoid implants of which 4 were loose.
15 had severe superior migration, 5 had moderate superior migration, and 2 had mild superior migration. 16 shoulders showed no superior migration.

Moderate to severe glenoid erosion was present in 12 of the shoulders at an average follow-up of more than 14.5 years. Glenoid erosion was correlated with superior migration of the humeral head and was more prevalent in patients with rheumatoid arthritis.

The mean time from the index arthroplasty to the revision surgery was 12 years
2 shoulders required early arthrodesis due to instability and deep infection. 

In addition, 10 of 54 shoulders required revision arthroplasty.
The indications for revision arthroplasty were rotator cuff failure in 4 shoulders (3 HSA and 1 TSA), glenoid loosening and humeral loosening in 4 TSA shoulders, glenoid erosion in 1 HSA
shoulder, and 1 traumatic periprosthetic fracture.

7 were revised to stemmed prosthesis: 1 for traumatic fracture and 1 for glenoid erosion 16 years after the index procedure.5 shoulders in 4 patients (4 rheumatoid arthritis, 1 avascular necrosis) were revised at 8 to 14 years after surgery for cuff failure and loosening. 

3 were revised to stemless reverse total shoulder arthroplasty due to rotator cuff failure at 23, 16, and 13 years after surgery.

Comment: This is an interesting and candid report by authors that include the designer of this system. Firstly, all shoulder surgeons recognize that the <50 year old patient needing an arthroplasty provides special challenges due to expectations, activities, and relatively uncommon diagnoses. Secondly, the patients in this series had a high preoperative incidence of rotator cuff issues, which place arthroplasty at increased risk of failure. Thirdly, the high rate of glenoid component loosening (often accompanied by humeral component loosening) and low clinical scores in the total shoulder group may be in part due to the technical challenge of glenoid arthroplasty when a substantial amount of the humeral head bone is retained as in these resurfacing arthroplasties - a feature that may compromise exposure.

Points of interest include the use of microfracture, the fact that 7 of the 10 revision arthroplasty were from resurfacing to stemmed prostheses, and the use of arthrodesis for two of the failures. 

All in all, this article provides an interesting contrast to our local practice and it will be of interest to see how all of us evolve in our management of the young, arthritic shoulder.

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Monday, January 19, 2015

Computer-assisted reverse total shoulder baseplate placement in model scapulae


Comparing conventional and computer-assisted surgery baseplate and screw placement in reverse shoulder arthroplasty.

These authors used a custom-designed system allowing computed tomography-based preoperative planning, intraoperative navigation, and postoperative evaluation.  Each of five surgeon performed 3 computer-assisted and 3 conventional simulated procedures on 3-dimensional CT reconstructed cadaveric shoulders. The 3-dimensional CT reconstructed postoperative units were digitally matched to a preoperative model for evaluation of entry points, end points, and angulations of screws and baseplate.

They found no difference in accuracy or precision of screws or baseplate entry points. Accuracy and precision were improved with the use of navigation for end points and angulations of 3 of the four screws. Navigated baseplate end point precision (but not the accuracy) was significantly improved.

The authors point out that the study was performed in a highly controlled in vitro environment with use of plastic and foam models representing a shoulder without exposure issues and without any significant bone deformity or bone loss.

Comment:
These results relate to a specific baseplate system. Other designs have parallel screws, so screw angulation is not an issue. Screw length is usually not an issue unless it is excessive.

In our practice we rarely obtain CT scans before reverse total shoulder arthroplasty except in cases of severe deformity or bone loss. This research did not include such pathoanatomy.

From this paper we do not know the additional cost or time necessary for the CT scans, the preoperative planning, or the making of the navigation tools. From the information presented it is not possible to determine the value (benefit/cost) of such a system or its utility in actual surgery.

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Predicting length of stay after total shoulder arthroplasty.

Predictors of length of stay after elective total shoulder arthroplasty in the United States

These authors searched the National Surgical Quality Improvement Program database between 2005 and 2011 for patients undergoing primary unilateral total shoulder arthroplasty (TSA) for data related to the length of hospital stay. A total of 2004 patients (average age 68.8 years, 57% women) were identified. Mean length of stay after TSA was 2.2 ± 1.7 days. 91% of cases were discharged in less than 3 days.

Renal insufficiency (OR, 11.35; P = .0002), increased age (OR, 2.13; P = .011), longer operative time (OR, 1.94; P = .0041), and American Society of Anesthesiologists class ≥3 (OR, 1.86; P = .0016) were the most significant risk factors for longer length of stay in a multivariate analysis.

Comment: In this case, length of stay was used as the primary outcome variable. Other important outcome variables would have been perhaps more interesting, such as rate of readmission, rate of revision, and functional outcome. This study shows - again - that the health of the patient is an important determinant of the result. Other factors that often have a profound effect are missing from this study, including the specific procedure performed, the experience of the provider, and the problem or diagnosis for which the procedure is performed. Along with patient factors these four form the 4 Ps that determine the quality of the result.

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Infection in shoulder arthroplasty - are we winning the battle?


Periprosthetic shoulder infection in the United States: incidence and economic burden

These authors used the Nationwide Inpatient Sample from 2002 to 2011 to study hemi, total and reverse total shoulder arthroplasty with specific reference to periprosthetic joint infection (PJI). They found that the rate of PJI remained essentially constant at 1% over this period. The risk of PJI was heightened by (1) weight loss/nutritional deficiency, (2) drug abuse, and (3) anemia from blood loss  or iron deficiency - each with an odds ratio of about 2. The risk was also increased in younger and male patients. Doing the math, the authors concluded that the increasing incidence of shoulder arthroplasty and a constant infection rate will result in greater overall shoulder PJI burden.

Comment: The concern with these numbers is that they are very likely to underestimate the actual rate of periprosthetic infections after shoulder arthroplasty. The authors used a methodology similar to that employed in identifying infection rates in the hip and knee arthroplasty population using the NIS database by identifying shoulder PJI from ICD-9 diagnosis code 996.66 (prosthetic infection) in conjunction with the shoulder prosthesis codes (81.80, 81.81, 81.88, 80.01). While this methodology captures cases diagnosed with PJI during the primary arthroplasty hospitalization as well as those that underwent arthrotomy and removal of arthroplasty hardware for diagnosis of infection, it is unlikely to capture periprosthetic infections with Propionibacterium (the most common organism cultured from failed arthroplasties) because these cases are frequently thought to represent 'aseptic' failure of the arthroplasty and because they often present late after the index joint replacement.  It seems likely that a substantial number of these cases would not be coded 996.66.  This problem does not exist (at least to the same extent) in hip and knee infections where Propionibacterium is relatively rarely identified.

The bottom line is that the problem of shoulder PJI is distinct from that in hip and arthroplasty where we appear to be winning the battle; in the shoulder, the battle is just beginning.

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Rapidly destructive glenohumeral arthritis


Rapidly destructive arthrosis of the shoulder joints: radiographic, magnetic resonance imaging, and histopathologic findings.

These authors present 9 women (mean age of 72 years (range, 63-85 years)) having shoulder arthroplasty that demonstrated a pattern of rapid collapse of the humeral head over 6 months from symptom onset as seen on plain radiography and magnetic resonance imaging (MRI) within 12 months from symptom onset. These patients had no history of  trauma, rheumatoid arthritis, steroid intake, neurologic osteoarthropathy, osteonecrosis, renal osteoarthropathy, or gout.

All patients showed a unique pattern of humeral head flattening, which appeared like a clean surgical cut with bone debris around the humeral head. MRI findings revealed significant joint effusion and bone marrow edema in the humeral head, without involvement of the glenoid. Pathologic findings showed both fragmentation and regeneration of bone matrix. Seven of the shoulders had large rotator cuff tears.

Comment: This description is interesting. This condition seems to have some features that resemble cuff tear arthropathy, others that resemble osteopenic fatigue fracture, and others suggesting avascular necrosis, while not being absolutely characteristic of any of these. We having a pending case in a 70 year old woman not exactly like those in this report, but similar in that over 8 months, without any evidence of infection or other underlying cause progressed from this characteristic picture of cuff tear arthropathy
 to this picture of destruction involving (in contrast to those in the report) the glenoid as well as the humeral articular surface.

The bottom line may be that there are many variations on the theme of glenohumeral arthritis, each requiring an individualized approach.

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