Wednesday, September 28, 2016

The ream and run procedure for shoulder arthritis

Shoulder arthritis is a condition in which the cartilage normally covering the ball and socket is lost because of wear, injury or prior surgery. Here are photos of an arthritic humeral head and glenoid socket.

Arthritis of the shoulder frequently affects individuals who do not have expectations of high levels of physical activity. These individuals are well served by a standard total shoulder replacement in which the socket is replaced with a plastic component as shown below.

This procedure offers a great chance for regaining a comfortable shoulder that is capable of activities such as golf, swimming, and hiking. However, because of concern regarding the possible adverse effects on the plastic socket, this procedure is not advised for individuals who wish to return to high levels of activity, such as weight lifting, chopping wood, or heavy work

For the last two decades at the University of Washington we have been developing a surgical treatment for severe shoulder arthritis designed for highly motivated individuals who desire to return to high levels of activity without concern about damage to a plastic socket. This procedure involves replacing the arthritic ball side of the joint with a chrome cobalt ball attached to a titanium stem inserted down inside the humerus – the same type of implant used in total shoulder joint replacement. This component is inserted without cement, using the patient’s own bone for fixation.

Instead of replacing the arthritic socket with a plastic implant, the socket bone is reamed to the desired shape.

The raw reamed bone heals as the patient performs specific postoperative motion exercises. Because the recovery from this procedure can be long and difficult, it is only recommended for healthy and dedicated patients who understand that the result depends largely on the effort they put in to the rehabilitation.

Many patients with shoulder arthritis are not good candidates for this procedure. Others choosing to have a ream and run do not achieve the desired result and may require additional surgery. However, many of the hundreds of patients having had the ream and run have been able to achieve prolonged levels of high shoulder function as shown in this video (click here).  We are continuing to study the long-term results of this operation and the factors that favor an excellent outcome.

Wednesday, September 21, 2016

Two sides of total shoulders, one with osteolysis and one with decentering and a B2 glenoid

Here are the films of a painful left shoulder several in a 40+ year old patient who had had a series of labral repairs and a hemiarthroplasty prior to the short stemmed implant total shoulder performed elsewhere. The shoulder has been progressively more painful for the three years after the total shoulder. The x-rays show humeral and glenoid osteolysis. The patient has scheduled a single stage revision.

Three months ago the patient presented to us with an arthritic right shoulder. The axillary "truth" view shows a biconcave glenoid with posterior decentering.

The patient had a total shoulder arthroplasty using conservative glenoid reaming, a standard glenoid component and an anteriorly eccentric humeral head component with a thin stem inserted with impaction grafting.

At the three month checkup, the right shoulder is comfortable, mobile and gaining strength. The x-rays are shown below.

Note the amount of humeral and glenoid bone preserved with this approach.

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'

Humeral shaft fracture after total shoulder arthroplasty

These are the x-rays of a right shoulder three years after a total shoulder arthroplasty. The shoulder was comfortable and fully functional.
Soon after the above films were obtained, the patient sustained a 6 foot fall landing with the mid humerus on the edge of a sharp rock. We were sent these x-rays:

The transverse midshaft humeral fracture is seen (a 'night stick' type of fracture). It is apparent that the splint was not controlling rotation.

We removed the arm from the splint and placed the arm in an ordinary sling. Three months later the fracture was healed clinically and radiographically and the shoulder essentially back to its pre fracture status.

Comment: While some had advised revision to a long stem prosthesis, in this case simple non-surgical management was effective.

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'

Reverse total shoulder - effects of bony and prosthetic glenoid lateralization

Finite element analysis of glenoid-sided lateralization in reverse shoulder arthroplasty

These authors conducted a 3D finite element analysis (FEA) to evaluate glenoid-sided lateralization in reverse shoulder arthroplasty and compared bony and prosthetic approaches to lateralization. Bony lateralization was accomplished by the insertion of a bone graft between the baseplate and the glenoid. Prosthetic lateralization was accomplished by either increasing the thickness of the base plate or increasing the thickness of the glenosphere.

Stress and displacement were evaluated at baseline and following 5, 10, and 15 mm of bony or prosthetic lateralization. 

Maximum stress for a 36 mm glenosphere without bone graft increased by 137% for the 5 mm graft, 187% for the 10 mm graft, and 196% for the 15 mm graft. Displacement also increased progressively with increasing graft thickness. 

Stress and displacement were reduced with a smaller glenosphere, inferior tilt of the baseplate, and divergent peripheral screws. 

Compared to bony lateralization, stress was lower with prosthetic lateralization through the glenosphere or baseplate. 

Displacement with 5 mm of bony lateralization reached recommended maximal amounts for osseous integration, whereas, this level was not reached until 10–15 mm of prosthetic lateralization. 

Baseplate stress and displacement in this FEA model was lower with a smaller glenosphere, inferior tilt, and divergent screws. 

Bony lateralization increased stress and displacement to a greater degree than prosthetic lateralization.

The authors concluded that at least 10 mm of prosthetic lateralization is mechanically acceptable during RSA, but that only 5 mm of bony lateralization is advised. 

Comment: There seems to be a trend away from the original Grammont design of reverse total shoulder

because of concerns about (1) scapular notching, (2) neurologic consequences of lengthening the arm, and (3) external rotator weakness from medialization of the humerus. With the advent of secure baseplate fixation, surgeons can reduce the notching and neurologic risks with a more anatomic reconstruction that includes East-West tensioning of the residual external rotators and other soft tissues. This lateralization can be accomplished by interposing a bone graft between the baseplate and the glenoid bone 

or by having a lateral offset built into the prosthesis. While bone graft has shown a high healing rate, there is concern about the possibility of compression of the graft with loss of the intended amount of lateralization. Our preference is for an implant system that allows variable lateral prosthetic offset combined with secure baseplate fixation. 

This article provides additional support for the use of prosthetic lateralization.

Tuesday, September 20, 2016

Intraoperative Manufacturing of Patient-Specific Instrumentation for Shoulder Arthroplasty

Intraoperative Manufacturing of Patient-Specific Instrumentation for Shoulder Arthroplasty: A Novel Mechatronic Approach

These authors propose a technology for the intraoperative production of patient-specific instrumentation, employing a table side machine, bespoke software and a disposable element comprising a region of standard geometry and a body of moldable material. 

They collected anatomical data from computed tomography scans of 10 human scapulae. For each the optimal glenoid guidewire position was digitally planned and recorded.

The technology was successfully able to produce sterile, patient-specific guides according to a pre-operative plan in 5 min.

The average guide wire placement accuracy was 1:58mm and 6.82 in the manual group, and 0:55mm and 1:76 in the guided group.

The readers may be interested in some of the steps

Comment: It is of interest to see the enthusiasm with which patient-specific instrumentation (PSI) is being pursued. In this in vitro laboratory example, intraoperative manufacturing of patient-specific instrumentation improved the guide wire placement by several millimeters. The clinical cost-effectiveness and practicality of such a system and its effect on clinical outcomes remain to be demonstrated.

Our approach to total shoulder arthroplasty does not involve PSI or a guide wire, but rather uses a nubbed reamer
to conservatively shape the face of the glenoid bone to match the back of the glenoid component without a specific attempt to change glenoid version.

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'

Acute failure of a hybrid glenoid component

Acute Failure of a Glenoid Component in Anatomic Shoulder Arthroplasty.

The authors remind us that glenoid loosening is the most common cause of failure in primary total shoulder arthroplasty and often occurs years after the initial surgery. In this case report, they present an unrecognized acute failure of a cemented hybrid glenoid component.

The patient was a 65-year-old man with persistent right shoulder pain and severely restricted range of motion approximately 10 months after a primary anatomic total shoulder performed for longstanding severe osteoarthritis with an intact cuff. The shoulder system was used for the index procedure included pegged, caged glenoid.

A CT arthrogram was ordered to evaluate if there was a rotator cuff tear but instead found that the glenoid component had dissociated and was sitting posterior to the humeral head .  The polyethylene glenoid component had disengaged from its metallic cage. One of the three metallic peg caps remained seated in the glenoid. 

Close inspection of the postoperative films, as early as those immediately following surgery in the postanesthesia care unit, confirmed that the glenoid had failed acutely.

At revision surgery, the glenoid component was retrieved from the posterior capsule. The component failure was seen to have occurred at the interface between one of the pegs and its metallic cap as well as at the cage component, which had disengaged from the polyethylene.

The authors point out that there have been prior recognized failures of this central cage locking mechanism. They suggest that this component requires “straight line” glenoid impaction, directly perpendicular to the face of the glenoid to prevent damage to the locking mechanism of the central peg as it engages the drilled hole. Failure to do so may disengage the central peg from the polyethylene.

Comment: This is points that each implant system has its particular features and that these need to be understood by the surgeon.

In our practice we use an all polyethylene component
our total shoulder arthroplasty is shown in this link.

Is a 'hip-style' prosthesis of use in cases of severe glenoid bone loss?

Primary shoulder arthroplasty using a custom-made hip-inspired implant for the treatment of advanced glenohumeral arthritis in the presence of severe glenoid bone loss

These authors present 37 patients with rotator cuff–deficient end-stage glenohumeral arthritis and severe glenoid bone loss (assessed as not amenable to treatment with standard anatomic or reverse total shoulder implants) who were treated  between 2006 and 2013 with a computer-aided design–computer-aided manufacturing (CAD-CAM) total shoulder replacement resembling a total hip prosthesis. 

An “acetabulum” for the uncemented titanium glenoid shell was created by concentric reaming of the lateral scapular angle to permit the shell to abut the anterior edge of the scapular spine while its inferior rim rests on the infraglenoid tubercle region and the anterior rim remains in line with the coracoid tip. The shell was then secured with 3 or 4 independently oriented nonlocking 3.5-mm titanium cortical screws to the scapular spine and the base of the coracoid and to the lateral column of the scapula and the remaining glenoid body.

Postoperatively, the pain level with activity decreased from 9.2 ± 1.7 to 2.4 ± 2.9 (P < .001). The Oxford Shoulder Score improved from 11 ± 8 points to 27 ± 11 points (P < .001), and the Subjective Shoulder Value (on a 0%-100% scale) improved from 23% ± 14% to 60% ± 24% (P < .001). Active forward elevation improved from 39° ± 23° to 63° ± 38° (P < .001), and external rotation improved from 6° ± 16° to 15° ± 17° (P = .001). Component revision was required in 6 of 37 patients (16%) (glenoid loosening in 1, humeral stem loosening in 3, periprosthetic fracture in 1, and prosthesis dislocation in 1).

The authors concluded that "the CAD-CAM TSR offers a reliable alternative for the treatment of end-stage glenohumeral arthritis with severe glenoid deficiency not amenable to standard anatomic or reverse total shoulder implants".

Comment: The one set of preoperative x-rays included 

suggest that the pathology may well have been treated with more conventional methods, such as a CTA prosthesis (see this link) or a standard reverse total shoulder (see this link). While the approach suggested by these authors may have a role, one must be concerned about the cost (which is not provided in the paper) and the risk of humeral and glenoid fixation (loosening), instability, and fracture. Although scapular spine fractures were not identified, it would appear that the spine may be weakened somewhat in this surgery.