Joint surface regeneration after a ream and run

Today in the office we had the pleasure of seeing a great example of the durable regeneration of the glenoid joint surface after a ream and run. Here are the preoperative films of a man in his mid 40s back in 2008. His SST was 6 out of a possible 12.

Here are his films from today's when his SST had increased to the maximum of 12 - four years after surgery. He reported no pain and full function of his shoulder, including weight lifting. Note the dark space between the metal humeral head prosthesis and the dense remodeled bone of the glenoid. Note also the solid fixation of the metal body in the shaft achieved by impaction grafting.

We anticipate that this arthroplasty will endure as will his shoulder function.

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Ream and Run for Shoulder Arthritis - initial clinical results - research foundation 3

Based on the encouraging laboratory studies demonstrated in the previous posts we began offering the ream and run procedure to selected and informed patients with arthritis of the shoulder who wished to avoid the risk of glenoid component failure and the activity limitations recommended for total shoulder replacement. In this procedure, we expose the arthritic glenoid (shown below),

remove the damaged cartilage, and then ream the bone to a spherical concavity (shown below) before replacing the humeral side of the joint using the technique explained in our April 6 post.

We were truly excited to see that in many cases, after completely removing the cartilage from the surface of the glenoid, new soft tissue regenerated to cover the reamed bony surface as shown by the dark space between the metal ball and the bone of the glenoid shown on x-rays taken a year after surgery. In the x-rays shown below, this regenerative zone is marked with a red "R".

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Ream and Run for Shoulder Arthritis - healing of the reamed bone - research foundation 2

Our May 16 post illustrated some long-forgotten work on the hip, showing that after reaming the bone of the hip socket, the surface of the bone could heal over with a smooth layer of soft tissue. My colleagues John Clark and John Sidles along with Kristi Gibbs and Tony Norman performed an in vivo lab study of the healing response of the canine socket in response to glenoid reaming followed by a period of articulation with a metal humeral implant. The full text of the article can be seen here. The normal canine socket in cross section is shown below. Note the reddish staining cartilage on the surface and the blue bone beneath.

The surface of the glenoid was then reamed using a specially designed reamer, shown below.

The smooth reamed surface is shown below.

A cross section after reaming is shown below. Note that the glenoid has a new contour different than that of the normal socket and that all of the cartilage has been removed. The many small bone plates (trabeculae) that previously supported the surface cartilage have been fractured by the reaming. We suspect that these many small fractures along with the accompanying bleeding bring stem cells and growth factors to the reamed surface to instigate the healing response.

The humeral head (ball side of the shoulder's ball and socket joint), was replaced with a special humeral prosthesis.

This is shown in place on a post-operative x-ray.

After 10 weeks of use, the cross-section of the glenoid shows substantial, but incomplete healing of the reamed surface by red-staining soft tissue.

On closer look, buds of regenerating soft tissue (red) can be seen pushing up from the reamed bony surface (blue-green) indicated by the arrow. The black dots in the soft tissue represent living cells. It is of note that this regenerative surface is powerful, pushing up against the resistance of the metal ball articulating with the reamed glenoid surface. This reminds me of the power of tree roots growing beneath the sidewalk.

At 26 weeks, a cross section of the glenoid shows complete healing with red soft tissue covering the reamed glenoid surface.

The regenerated soft tissue is firmly bonded to the underlying bone by arching strands of fibrous tissue. This type of fixation could not be accomplished with a plastic socket or by interposing a graft of capsule or meniscus between the humeral head and glenoid. Note also that the red soft tissue contains living cartilagenous cells, confirming that fibrocartilage has regenerated on the surface.

While this surface covering is not the same as the hyaline cartilage that covers normal joints, it appears to provide a smooth and durable covering for bone articulating with a metal ball. In contrast to an artificial surface that deteriorates over time, this living, smooth joint surface firmly bonded to the underlying bone has the potential to remodel continuously with use.

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Ream and Run for Shoulder Arthritis - Genesis

  Three observations led us to consider the ream and run procedure for shoulder arthritis.
First, some our patients, of any age, did not want to have limits usually imposed by surgeons after a total shoulder joint replacement as we discussed in the May 2 post.
Second, patients with failed glenoid components often experienced substantial improvement after we revised their shoulder by removing the plastic glenoid component, reamed the remaining glenoid bone to a smooth concvity and avoided re-insertion of another glenoid component. Such an example is shown below. This shoulder had received a total shoulder by another surgeon. The glenoid component broke and the patient came to us for revision surgery. We removed the broken elements and the humeral head component, washing the joint thoroughly. We then reamed the glenoid bone to a smooth concavity and inserted a new humeral head component. The X-rays shown below are 8 months after surgery showing a smooth set of joint surfaces; the patient is now substantially improved with respect to comfort and function and is progressively returning to full activities. Close inspection of these images reveals a dark layer of regenerative tissue between the metal ball and the bone of the glenoid. Furthermore, the defect in the bone previously occupied by the polyethylene glenoid component has healed in without the need for bone grafting.

Third is the often forgotten experience with close inspection of the socket surface after mold arthroplasty of the hip reflected also in a second article on mold arthroplasty of the hip. Basically the experience was that inserting a mold in the hip joint between the smoothed ball and socket led to a smooth regenerative surface on the concave side of the joint (acetabulum) as shown in the figures below from these two articles.

We were thus led to the realization that the socket side of a joint had the capacity to regenerate a smooth bilogical covering, securely attached to the underlying bone that would be immune to the risk and limitations of plastic socket wear or loosening. Furthermore, it appeared that some patients could regain high levels of comfort and function without plastic, even though there was nothing interposed between the metal ball and the bone of the prepared socket.

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You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty,  and rotator cuff surgery.

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