Monday, September 22, 2014

Stemless reverse total shoulder

The TESS reverse shoulder arthroplasty without a stem in the treatment of cuff-deficient shoulder conditions: clinical and radiographic results.

These authors, including the co-conceptor of the design, enrolled 101 patients having 105 stemless reverse total shoulders in a prospective study, with a minimum follow-up period of 24 months. 91 procedures in 87 patients (61 men and 26 women), with a mean age of 73 years, were available at a mean follow-up of 41 months (range, 24-69 months).

Ninety-six percent of patients rated their satisfaction as good or excellent. Mean flexion was 143° (range, 90°-170°), and mean external rotation was 39° (range, 20°-70°). The Constant score improved from 40 points preoperatively to 68 points at last follow-up (P < .001). The mean American Shoulder and Elbow Surgeons score was 24 points. The mean neck-shaft angle was 154° (range, 142°-165°). Inferior scapular notching occurred in 17 cases (19%). The notching rate was higher when the glenometaphyseal angle increased (P < .001), when the inferior tilt decreased (P = .003), and when the neck-shaft angle increased. The authors reported no evidence of component loosening.

Comment: These patients had the diagnosis of either cuff tear arthropathy or failed cuff repair - patients with the important diagnoses of failed anatomic arthroplasty or fracture were not included, probably because this prosthesis is not suitable in these situations.

The preoperative flexion averaged 96 degrees and abduction averaged 89 degrees with some patients having as much as 160 degrees of preoperative elevation. Thus all these patients did not have the classic indications for a reverse (pseudoparalysis or anterosuperior escape).

The results point out the variability in the position in which the components can be inserted.

Rotator cuff repair vs. non-repair of cuff tears in individuals over the age of 60 years.

Is rotator cuff repair appropriate in patients older than 60 years of age? Prospective, randomised trial in 103 patients with a mean four-year follow-up

These authors compared surgical rotator cuff repair to acromioplasty and biceps tenotomy in patients older than 60 years of age with a mean follow-up of 4 years.

Exclusion criteria included subscapularis tear, spontaneous long head biceps tear, and irreparable tear as determined arthroscopically.

Patients were randomly allocated to acromioplasty and tenotomy (AT group) or to acromioplasty, tenotomy, and tendon suture (CR group). In the repair group tendon suture was consistently achieved using metal anchors inserted into the tip of the greater tuberosity after abrasion of the footprint, in a single-row (n = 21) or double-row (n = 33). After surgery patients  wore a sling for 4 weeks with
passive self-rehabilitation on day 1.  After 4 weeks, physiotherapy sessions were prescribed if needed.

Of 130 initially included patients older than 60 years of age and having rotator cuff tears deemed amenable to surgical repair, 103 (79%) were evaluated after a mean of 4 years. 
The tear was distal in 41 patients, intermediate in 40, and retracted in 22. 

The complication rate was 4%. The mean Constant Score was 44 preoperatively; values after 4 years were 76 overall. The repair group had slightly greater Constant Scores (78) than the acromioplasty group (73). Less than 2/3 rds of the repairs (63%) were healed by sonography. 

The Constant Score was significantly better when tendon healing was achieved (82/73, P < 0.001). In the AT group, the acromio-humeral distance was significantly smaller (6.9 mm/7.8 mm, P = 0.03) and eccentric humeral head position was more common (44%/26%,P = 0.01).

Comment: It would have been interesting to know how many of the shoulders with cuff tears examined arthroscopically were deemed 'irreparable' and how this determination was made. Because the constant score includes a strength component, it is expected that shoulders with healed repairs would score better than those with unhealed or unrepaired tears. It is interesting to note, however, that the difference between repair and non-repair reported in this article did not reach the level of the minimal clinically important difference for rotator cuff tears (=10). Finally it is of note that acromioplasty sacrifices part of the coracoacromial arch and may not be benign for unrepaired cuffs. For that reason, we prefer the smooth and move procedure when cuff repair is not possible or desirable.

Consultation for those who live a distance away from Seattle.

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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'

Resurfacing humeral arthroplasty can cause bone loss beneath the component

Stress-shielding induced bone remodelling in cementless shoulder resurfacing arthroplasty: A finite element analysis and in-vivo results

These authors explore the concern that cementless surface replacement arthroplasty may result in stress shielding and bone remodelling beneath the prosthesis. They studied bone remodelling using 3-dimensional finite element analysis (FEA) as well as evaluation of contact radiographs from human implant retrievals. 
FEA included one native humerus model with a normal and one with a reduced bone stock quality. The compressive strains were evaluated before and after virtual resurfacing prosthesis implantations.

They also studied the bone remodelling and stress-shielding pattern of 8 human cementless surface replacement arthroplasty retrievals.

FEA revealed for both bone stock models increased compressive strains at the stem and outer implant rim for both cementless surface replacement arthroplasty designs indicating an increased bone formation at those locations. Unloading of the bone was seen for both designs under the central implant shell indicating high bone resorption. Those effects appeared more pronounced for the reduced than for the normal bone stock model. 

These assumptions of the FEA were confirmed in the cementless surface replacement arthroplasty retrieval analysis which showed bone apposition at the outer implant rim and stems with highly reduced bone stock below the central implant shell. Overall, clear signs of stress shielding were observed for cementless surface replacement arthroplasty in the in-vitro FEA and human retrieval analysis. Especially beneath the central part of the cementless surface replacement arthroplasty the bone stock was highly resorbed. 

Comment: As pointed out in our post from two days ago, resurfacing humeral hemiarthroplasty has been proposed as a more conservative approach to managing shoulder arthritis, but it has the disadvantages of (1) non addressing the glenoid side of glenohumeral arthritis, (2) blocking access to the glenoid if a glenoid component is considered, and (3) making it difficult to detect if the humeral component is subsiding. This article adds 'stress shielding' and resulting loss of the supporting bone as a fourth concern.

Saturday, September 20, 2014

Is digital templating of the humeral component worthwhile?

Reliability and accuracy of digital templating for the humeral component of total shoulder arthroplasty

These authors evaluated the interobserver reliability and accuracy of pre-operative digital templating for humeral head size, stem size and neck angle for total shoulder arthroplasty in 25 patients. Four surgeons used pre-operative radiographs and templating software to generate templates of the humeral head, stem and neck for each patient.

Interobserver reliability was fair to substantial (κ = 0.26 to 0.71) for head size, fair to substantial (κ = 0.39 to 0.72) for stem size and slight to fair (κ = 0.16 to 0.34) for neck angle. Templated head size, stem size and neck angle had accuracies of 53%, 77% and 68% within one size variation, respectively.

The authors concluded that digital templating was not a useful guide for pre-operative surgical planning and should not be used to select a prosthesis.

Comment: In our practice, component sizing is determined by intra-operative trialing rather than templating. A potential trap of committing to the humeral stem size seen on the AP view is that the diameter is usually smaller on the lateral view - the humeral canal is not a circle in cross section.  Templating is used to anticipate problems that may be encountered at surgery. For example, the humeri of smaller more elderly individuals may have large endosteal canal diameters, yet a prosthesis that fills this canal may be too large for the proximal humeral metaphysis. 

As another example, posttraumatic malunions leaving the proximal humerus in varus may place the tuberosities over the proximal extrapolation of the canal, warning us that conventional placement of the humeral canal may not be possible.

Humeral head resurfacing, analysis of migration of the component on the humerus

Evaluation of periprosthetic bone mineral density and postoperative migration of humeral head resurfacing implants: two-year results of a randomized controlled clinical trial

These authors randomly allocated 32 patients (13 women), mean age 63 years (range, 39-82 years), with shoulder osteoarthritis to either a Copeland (n = 14) or Global C.A.P. (n = 18) humeral head resurfacing implant. Patients were monitored for 2 years with radiostereometry, dual-energy X-ray absorptiometry, Constant Shoulder Score, and the Western Ontario Osteoarthritis of the Shoulder Index.

At 2 years, total translation was 0.48 mm (standard deviation [SD], 0.21 mm) for the Copeland and 0.82 mm (SD, 0.46 mm) for the Global C.A.P. (P = .06).

The Copeland implant tended to migrate laterally and rotate into valgus, whereas the Global C.A.P. tended to translate distally and laterally.

Five (15%) of these implants were revised within the two year followup period. These revised implants demonstrated greater translation (0.58 mm (SD, 0.61 mm)) than non revised components (0.22 mm (SD, 0.17 mm)). The revised implants tended to translate in anterior, distal, and lateral
directions and to rotate into valgus. The reasons for revision included greater tuberosity fracture (1), pseudoparalysis (1), cuff rupture (2) and peri-implant arthritic changes (1). Four of these failures were revised to stemmed implants with apparently good results; one was revised to a reverse total shoulder.

While the bone mineral density was higher for the Copeland prosthesis, there was no difference in the clinical outcomes.

Comment: While considered to be more 'conservative' than a conventional stemmed humeral head replacement, the resurfacing humeral head replacement can present problems with migration after implantation as well as with positioning (as shown here and here).

The inclusion criteria were "individuals aged 18 to 85 years with shoulder osteoarthritis and cartilage defects involved on the humeral rather than on the glenoid side of the joint".  In our experience it is unusual to encounter osteoarthritis that involves only one side of the articulation.

At this point, we've yet to find an application for a resurfacing prosthesis in our practice.

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

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To see the topics covered in this Blog, click here

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'

Patient specific guides for glenoid placement, is the benefit worth the cost and time?

Three-dimensional planning and use of patient-specific guides improve glenoid component position: an in vitro study.

These authors performed CT scans on 18 cadaver scapulae, "virtually" placed glenoid components, and then created cadaver-specific guides for positioning a guide pin used for glenoid placement. After placement, a second CT scan was performed to compare the planned to the actual pin position. The actual placement was close the the planned placement.

For us and for many surgeons, standard total shoulder practice is to assess preoperative glenohumeral pathoanatomy using standardized axillary radiographs and to fit the glenoid prosthesis to the bone using conservative reaming and conventional guides for drill hole placement, tailoring component position to balance stability of the articulation with quality bone support for the glenoid prosthesis. Guide pins are avoided because of the concern for breakage or inadvertent advancement toward the thorax during reaming. 

While it is recognized that shoulders with the bad arthritic triad create difficulties for the arthroplasty surgeon and have on average poorer results than those shoulders without glenoid retroversion, posterior humeral subluxation and biconcavity, it has yet to be demonstrated that 'normalizing' glenoid version or the use of posteriorly augmented glenoid components improves the clinical outcomes for patients.

Against this background, some have advocated the use of 3-D scans, reconstructions, and the use of proprietary software to create patient specific instruments to guide the placement of a glenoid guidepin in a position that will change the glenoid version toward that found in unarthritic shoulders. 

This study was performed in dry cadaver scapulae without arthritis and absent the presence of the humerus and the soft tissues we encounter at surgery. It did not proceed to study glenoid component implantation, but stopped at the point of guide pin positioning.

It is not clear whether additional surgical exposure is required to use this system. While the title suggests that patient specific guides 'improves' glenoid component position, there is no comparison of this method to other methods. The study does not indicate the added time, added cost of this approach,  or increased open wound time required for this method nor does it demonstrate its utility in intact shoulder specimens or in the performance of actual shoulder arthroplasty.

The bottom line is that the application of new technology needs to be justified by a documented benefit to the patient that offsets the cost, learning curve, and potential added risks in its use.

It is worthwhile to compare this paper to another recent one: Small Improvements in Mechanical Axis Alignment Achieved With MRI versus CT-based Patient-specific Instruments in TKA: A Randomized Clinical Trial.

These authors compared the accuracy of MRI- and CT-based patient-specific instrumentation with conventional instrumentation and with each other in total knees. The three approaches also were compared with respect to validated outcomes scores and duration of surgery.

They conducted a randomized clinical trial in which 90 patients were enrolled and divided into three groups of comparable patients: CT-based, MRI-based patient-specific instrumentation, and conventional instrumentation. Component rotation was measured on CT scans. 

Compared with conventional instrumentation MRI- and CT-based patient-specific instrumentation showed higher accuracy, but the differences were small. There were no differences in the postoperative Knee Society pain and function and WOMAC scores among the groups.

The authors conclude,  "Although this study supports that patient-specific instrumentation increased accuracy compared with conventional instrumentation and that MRI-based patient-specific instrumentation is more accurate compared with CT-based patient-specific instrumentation regarding coronal mechanical limb axis, differences are only subtle and of questionable clinical relevance. Because there are no differences in the long-term clinical outcome or survivorship yet available, the widespread use of this technique cannot be recommended."

In this vein, recommended reading is the spotlight and the Editorial "our love affair with technology and the choices we make'.  I quote the last sentence, " Finally, as surgeons, we need to be mindful when we use some new implant, technology, or approach as a practice-building move, and to do so only when we are certain – based on thoughtful reading and evaluation – that it really clears the bar in terms of safety and efficacy. If we cannot turn off the projector, let’s at least acknowledge that it is time to roll the credits.

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

To see the topics covered in this Blog, click here

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'

Thursday, September 18, 2014

Which is better physical therapy or surgical repair for rotator cuff tears of 3 cm or less

Tendon Repair Compared with Physiotherapy in the Treatment of Rotator Cuff Tears

These authors have performed a remarkable Level I intention to treat analysis of 103 cases of small acute or chronic cuff tears (3 cm or less) confirmed by both MRI and sonography that did not have stiffness or substantial muscle atrophy. Cases were block randomized to either (a) repair (with or without biceps surgery) or (b) supervised physical therapy (PT) with the possibility of secondary repair. Secondary surgery was offered to patients in the PT group if symptoms persisted after 15 PT visits. Clinical and sonographic followup was 98% at 5 years.

The authors selected the Constant Score as the primary outcome of interest. This score was only slightly better for the group having surgical repair: 79.8 ± 15.0 as compared to 74.2 ± 20.3 for the PT group. P = .05.

The failure rates in the two groups were comparable:
(1) Over 14 of the tears treated with PT had progression of the tear size > 5mm, some related to trauma. It is not possible to know if repair of these tears would have been successful. Twelve nonoperative patients reported an insufficient treatment effect and desired surgical treatment.

(2) For the surgical patients, a re-tear (or non-healing) was diagnosed 15 patients. The recurrent defect was full-thickness in eight patients (13%) and a partial-thickness in seven patients (12%). These are essentially the same results as found in the classic article by Harryman et al reported over two decades ago.  There was no mention of whether complications occurred in the surgery group. It is not stated if the re-tears required repeat surgery.

A biceps tenodesis was performed in over one third of cases in the primary tendon repair group; no biceps tenodeses were performed in the physical therapy group. Thus, if over 1/3 of patients in this series had biceps tendon pathology, this pathology went untreated in the PT group.   One could wonder if such untreated pathology might have accounted for the small difference in the two outcomes.

Comment: Our approach to rotator cuff tears remains unaltered: acute tears resulting in a substantial change of shoulder function deserve strong consideration for prompt surgical repair if the patient is healthy and active as long as there is no reason to believe the tendon is of poor quantity or quality (i.e. patient is elderly, a smoker, has had steroid injections, has atrophy, massive tear, retraction).

Chronic tears deserve a good try at non operative management. If non-operative management is not successful, consideration can be given to a smooth and move or a repair depending on the quantity and quality of the tissue encountered at surgery.

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

To see the topics covered in this Blog, click here

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'