CoCr Ream and Run - comparison to aTSA, how much wear, how much does it matter, satisfaction

The ream and run (RnR) is a glenohumeral arthroplasty in which the arthritic humeral head is replaced with a chrome-cobalt humeral head similar to that used in conventional total shoulder arthroplasty. The key difference is that rather than implanting a plastic glenoid component, the glenoid bone is conservatively reamed to a concentric concavity and allowed to remodel during the rehabilitation period. This procedure eliminates the limitations and risks of loosening associated with a plastic glenoid component.

Four recent papers contribute to our understanding of the Ream and Run. Note that none of the authors have a financial conflict of interest with the companies making the implants used in these studies.

Brad Carofino, former University of Washington Shoulder Fellow, working in Virginia Beach has provided the most rigorous data on the ream and run to come from a center outside Seattle. Here are two of his recent publications

Paper #1 Comparison of short- and midterm outcomes inpatients following ream-and-run and anatomic total shoulder arthroplasties   J. Shoulder Elbow Surg (2025) 34, 794-802. A matched  cohort study compared ream and run (RnR) outcomes to anatomic total shoulder arthroplasty (aTSA).  The RnR procedures were all performed by an individual surgeon. A multicenter database was used to provide the matched cohort of patients who underwent the aTSA procedure. Only male patients were included; average age was 56 years. 

Of note this surgeon accepts 2 - 8 mm of diametral mismatch between the humeral head and the reamed glenoid when performing the RnR, selecting the reamer size that removes the least amount of bone without attempting to change preoperative glenoid version. When selecting the humeral head implant size, he selected a head diameter to approximate the patient’s anatomy; 54- and 56- mm-diameter heads were the most used sizes. For head height, the surgeon favored the thinnest option for that diameter (15 or 18 mm). Because patients are encouraged to obtain 160 degrees of passive forward elevation within the first few days, range of motion exercises are started the day of surgery and performed 3-5 times per day for the first 6 weeks.

The Simple Shoulder Test and ASES scores for RnR were not inferior to those for aTSA at a mean three-year follow-up; revision rates and satisfaction were essentially the same.  

 

RnR outcomes were not different between patients with preoperative type A and type B glenoids. 

Preoperative humeral decentering was corrected (50% indicates that the humeral head is centered on the glenoid).

Paper #2. Patient self-selection does not influence postoperative improvements in pain, function, or satisfaction in ream-and-run arthroplasty patients  Shoulder Elbow Surg. 2026 Apr;35(4):989-994.  determined whether patients who specifically seek out the RnR are representative of the general shoulder arthritis population.  The authors compared two groups from their practice: self-selectors (patients who specifically sought the ream and run) and walk-in candidates (patients who were offered the procedure by their surgeon and accepted, without having sought it out). 

Patients self-selecting the RnR arthroplasty reported pain and functional improvements as well as satisfaction ratings similar to those who were not specifically seeking out the procedure. Both groups achieved approximately 84–88% of maximum possible improvement on the SST and approximately 78% on the ASES. More than 93% of patients in both groups reached the minimal clinically important difference.

Two papers came from the University of Washington Shoulder Team.

Paper #3 Which shoulder functions correlate with patient satisfaction after primary shoulder arthroplasty?  J Shoulder Elbow Surg. 2026 Jan;35(1):19-27. The ability to sleep comfortably, to perform overhead function and to toss a softball were most predictive of satisfaction. 

Paper #4 Characterizing glenoid wear after hemiarthroplasty with concentric glenoid reaming: a study of 113 arthroplasties at a mean of 6.7 years of follow-up J Shoulder Elbow Surg. 2026 Apr;35(4):995-1002. assessed medial migration of the humeral head and its relation to clinical outcome. Glenoid wear was quantified by measuring the position of the humeral head center of rotation relative to a line passing through the lateral tip of the acromion and parallel with the superior and inferior margins of the glenoid articular surface (below on the left: the immediate postoperative film, on the right: the five year postoperative film) 

Medialization occurred predominantly in the first two years as the reamed glenoid adapted to load and tended to level off thereafter. The characteristic amount of medialization at 10 years was 3.5 mm.

Of importance is the observation that medialization did not correlate with outcome: patients with greater medialization achieved SST and ASES scores equivalent to those with less wear. Overall satisfaction exceeded 97%. Twelve shoulders were revised for stiffness or malposition, eight of these were revised to a repeat RnR, one to aTSA, one to RSA, one to CTA hemiarthroplasty, and one was a soft tissue release.

Conclusion: These studies and the preceding literature suggest that RnR with a chrome-cobalt humeral head and conservative reaming without version correction delivers consistent, durable results across follow-up durations, across glenoid morphologies, across surgeons, and across patient selection pathways. 

These studies provide data to which alternative approaches, such as pyrocarbon and ceramic heads can be compared.

For younger, active patients with cuff-intact glenohumeral arthritis who wish to avoid the risk of glenoid component loosening, the ream and run merits consideration as a first-line operative treatment. 

Here's an example of an active, athletic man who had bilateral RnRs. The right 18 years ago and the left 11 years ago. The x-rays below show the preop and current x-rays of each shoulder. He has been able to return to essentially full activity with each.

He kindly gave permission to show the videos of his shoulder motion that I took recently. 

This outcome shows what a motivated patient can accomplish after a RnR.

For younger, active patients with cuff-intact glenohumeral arthritis who wish to avoid the risk of glenoid component loosening, the ream and run merits consideration as a first-line operative treatment. 

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Where's the wear, where's the osteolysis? 17 year ream and run followup

 A 55 year old active man with limiting pain and stiffness of the left shoulder presented with these x-rays.

Wishing to avoid the risks and limitations associated with the plastic glenoid component used in conventional total shoulder arthroplasty, he elected to proceed with a ream and run procedure.

At followup 17 years after his procedure, he demonstrated excellent comfortable range of motion. 

X-rays showed stable fixation of the impaction autografted humeral component along with healing of the reamed glenoid without evidence of glenoid wear and no humeral osteolysis.

Comment: While glenoid erosion can occur after hemiarthroplasty with a chrome cobalt humeral head, in many cases, as in this one, the reamed glenoid heals to a stable surface. Additional clinical research is needed to determine the factors associated with glenoid wear.

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).

The vicious circle of glenohumeral arthritis - can it be stopped?

In 1990, the late Doug Harryman published Translation of the humeral head on the glenoid with passive glenohumeral motion in which he described the effects of anterior capsular tightness on posterior humeral head translation in osteoarthritis. Here is a figure from that article.

The effect of anterior capsular tightness was further described in Practical Evaluation and Management of the Shoulder (see this link)

illustrating that this posterior translation can result in posterior glenoid wear

In Edge displacement and deformation of glenoid components in response to eccentric loading. The effect of preparation of the glenoid bone, Collins et al found that the thickness of glenoid articular cartilage was greatest in its posterior aspect, making this part of the glenoid socket at greatest risk for wear. In the case of the type B1 glenoid - where there is no obvious bony biconcavity - there is in fact a biconcavity in the articular surface due to loss of this posterior glenoid articular cartilage.  

                                         

which progresses to posterior glenoid bone wear becoming a type B2 glenoid

                                                     

as revealed by the axillary "truth" view

                                     

This posterior decentering is associated with loss of external rotation

Thus we have the vicious circle in which tightness and stiffness of the anterior capsule leads to posterior decentering of the humeral head leading to erosion of the posterior articular cartilage and bone which leads to limited external rotation leading to more tightness and stiffness of the anterior capsule.

as illustrated here:

             

A recent article The Association Between Anterior Shoulder Joint Capsule Thickening and Glenoid Deformity in Primary Glenohumeral Osteoarthritis builds on these points. These authors sought to determine the relationship between anterior capsular thickening and glenoid deformity in primary glenohumeral osteoarthritis in 134 osteoarthritic shoulders with magnetic resonance imaging (MRI) and computed tomography (CT) scans. 

They found that the anterior capsule was thickest in glenoid types B2 (5.5 mm) and B3 (6.1 mm), and thinnest in A1 (3.7 mm). Adjusted for age and sex, glenoid types B2 and B3 showed the strongest association with increased anterior capsule thickness, compared to glenoid type A1. Increased capsular thickness correlated with greater glenoid retroversion and posterior humeral head subluxation. In multivariable analysis, for every 1-mm increase in anterior capsular thickening, there was an adjusted mean increase of 3.2 degrees in glenoid retroversion and a 3.8% increase in posterior humeral head subluxation.

Taken together, these observations bring up the question: can interventions (such as mobilization exercises or anterior capsular releases) implemented early in the course of osteoarthritis interrupt the vicious cycle?

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.

Follow on twitter: https://twitter.com/shoulderarth

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Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link).

How to x-ray the shoulder (see this link).

The ream and run procedure (see this link).

The total shoulder arthroplasty (see this link).

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

The smooth and move procedure for irreparable rotator cuff tears (see this link).

Shoulder rehabilitation exercises (see this link).

Origins of the ream and run for shoulder arthritis and an example of its durability.

 The first ream and run procedures were not done for shoulder arthritis, but rather for arthritis of the hip.

In a classic article by M. N. Smith Peterson (see this link), the author reviewed his treatment of hip arthritis by reaming the acetabulum and covering the femoral head with a mould (or mold) made of glass. This thought was apparently inspired by a shard of glass he found in a patient’s back with a benign synovial-like membrane around it. He tried various materials for the mould, including glass and vitallium:

On the acetabular side, he used a convex reamer very similar to those we use today for the ream and run

His concept is expressed below

His conclusion is shown below

Here is an example of a 6.5 year followup.

He used this method to take down hip fusions.

In 1969 W.H.Harris published, "Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. This was a case series of mold arthroplasties performed between 1945 and 1965 by three orthopaedic icons: M.N. Smith-Peterson, Otto E. Aufranc, and Morton Smith-Peterson. In this procedure the acetabulum was reamed and the reamed femoral head was covered with a metallic cup. Some of the preoperative and followup radiographs are shown below.

All of the procedures is-crc standard arthroplasties with

decortication arid reaming of both the head and acetabulum except for tis’o in ‘which

the cup was placed on the mid-portion of the femoral head ansd tivo in is-hich the cup

‘was seated against the periphery of the acetabulum in preference to inserting it

more deeply insto an e;;kxploded socket

 The clinical results as summarized by the authors are summarized below.

kxploded socket

While there are few histological studies of the effect of this early hip procedure the one below suggests the presence of fibrocartilage over the reamed acetabular surface.

This was actually this figure that inspired our exploration of the ream and run procedure. Histology from an animal model shown below immediately after reaming (left) and six months after showing growth of fibrocartilage over the reamed surface (right) (see this link).

In case you're curious, American English has no "mould", and British English has no "mold". In other words, the word referring to (1) the various funguses that grow on organic matter or (2) a frame for shaping something is spelled the same in both uses, and the spelling depends on the variety of English.

Here's an example of the durability of a reamed glenoid with a humeral hemiarthroplasty "mold". A 62 year old physically active man presented with pain and stiffness in the right shoulder. On presentation he had these x-rays. 

To avoid the risks and limitations associated with a prosthetic glenoid component, he elected to have the ream and run procedure.

A one year after his procedure he had full return of comfort and function and these radiographs

Here are his x-rays at two years after surgery

At 10 years his function remained excellent. His x-rays at 10 years are shown here. Note the thin soft tissue layer between the prosthetic humeral head and the reamed glenoid bone.

Our technique for the ream and run is shown in this link.

How you can support research in shoulder surgery Click on this link.

Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link).

How to x-ray the shoulder (see this link).

The total shoulder arthroplasty (see this link).

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

The smooth and move procedure for irreparable rotator cuff tears (see this link).

Shoulder rehabilitation exercises (see this link).

Follow on twitter: Frederick Matsen (@shoulderarth)