Dull reamers can kill glenoid bone

Thermal effects of glenoid reaming during shoulder arthroplasty in vivo

These authors point out that glenoid component loosening is a common cause of failure of total shoulder arthroplasty. It has been proposed that the heat generated during glenoid preparation may reach temperatures capable of producing osteonecrosis at the bone-implant interface. They hypothesized that temperatures sufficient to induce thermal necrosis can be produced with routine drilling and reaming during glenoid preparation for shoulder arthroplasty in vivo. Furthermore, they hypothesized that irrigation of the glenoid during reaming can reduce this temperature increase. They used real-time, high-definition, infrared thermal video imaging to determine the temperatures produced by drilling and reaming during glenoid preparation in ten consecutive patients undergoing total shoulder arthroplasty. The maximum temperature and the duration of temperatures greater than the established thresholds for thermal necrosis were documented. 

The first five arthroplasties were performed without irrigation and were compared with the second five arthroplasties, in which continuous bulb irrigation was used during drilling and reaming. A one-dimensional finite element model was developed to estimate the depth of penetration of critical temperatures into the bone of the glenoid on the basis of recorded surface temperatures.

The first hypothesis was supported by the recording of maximum surface temperatures above the 56°C threshold during reaming in four of the five arthroplasties done without irrigation and during drilling in two of the five arthroplasties without irrigation. The estimated depth of penetration of the critical temperature (56°C) to produce instantaneous osteonecrosis was beyond 1 mm (range, 1.97 to 5.12 mm) in four of these patients during reaming and one of these patients during drilling, and two had estimated temperatures above 56°C at 3 mm. 

The second hypothesis was supported by the observation that, in the group receiving irrigation, the temperature exceeded the critical threshold in only one specimen during reaming and in two during drilling. The estimated depth of penetration for the critical temperature (56°C) did not reach a depth of 1 mm in any of these patients (range, 0.07 to 0.19 mm).

They concluded that temperatures sufficient to induce thermal necrosis of glenoid bone can be generated by glenoid preparation in shoulder arthroplasty in vivo. Frequent irrigation may be effective in preventing temperatures from reaching the threshold for bone necrosis during glenoid preparation.

Another article is relevant, Thermal and Cutting Dynamics of New and Used Glenoid Reamers During Total Shoulder

These authors suggest that inaccurate reaming and thermal osteonecrosis from heat generated during the reaming process may contribute to TSA failure by creating a suboptimal bone-implant interface. They investigated the differences in depth penetration and heat generation of used community glenoid reamers in comparison to previous unused reamers.

They used a MTS Servohydraulic machine to test new and used community glenoid

reamers by applying the clinically relevant force of 54.7 N over a defined time. The depth of

penetration was measured via the MTS machine and the thermal profile was obtained via an

infrared camera. The used reamers were then set by the MTS machine to reach the same depth as the new reamers for all respective sizes while recording the force differential generated and capturing the thermal profile. 

At a constant force and time, the new reamers penetrated a greater depth (4.18 mm ± 2.17 mm) than the community used reamers (0.41 mm ± 0.22 mm), a difference of 3.80 mm ((95% CI, 2.23 mm to 5.31 mm), p < 0.001) without generating temperatures above 50°C. 

When programmed to reach the same average depth as the new reamers of equivalent sizes, the community reamers generated more heat on average (50.02 °C ± 2.88 °C), a difference of 5.98 °C ((95% CI, 3.40 to 8.53), p < 0.001). The used reamers on average also required 218.20 N more force than the new reamers (54.71 N ± 28.69 N) to reach the same depth, with the medium (303.47 N ± 96.71 N) and large (261.72 N ± 55.28 N) reamers specifically requiring the largest amount of force.

They concluded that the sharpness of glenoid reamers varies in the community. In order to reach the necessary depth for adequate fixation of implants, orthopedic surgeons may be required to exert a substantially larger force when using dulled reamers in comparison to sharp reamers. As a consequence, the heat generated could increase the risk of thermal osteonecrosis contributing to glenoid loosening.

Comment: These articles point to the ability of reaming to generate bone-killing levels of heat in the glenoid bone. This heat may interfere with the healing of bone in a ream and run procedure and with the stability of fixation in total shoulder arthroplasty.

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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)

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

The total shoulder arthroplasty (see this link).

The ream and run technique is shown in this link.

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

Shoulder rehabilitation exercises (see this link).

Glenoid reaming can generate enough heat to kill bone - relevance to total shoulder and ream and run arthroplasty

Thermal effects of glenoid reaming during shoulder arthroplasty in vivo

These authors point out that glenoid component loosening is a common cause of failure of total shoulder arthroplasty. It has been proposed that the heat generated during glenoid preparation may reach temperatures capable of producing osteonecrosis at the bone-implant interface. They hypothesized that temperatures sufficient to induce thermal necrosis can be produced with routine drilling and reaming during glenoid preparation for shoulder arthroplasty in vivo. Furthermore, they hypothesized that irrigation of the glenoid during reaming can reduce this temperature increase. They used real-time, high-definition, infrared thermal video imaging to determine the temperatures produced by drilling and reaming during glenoid preparation in ten consecutive patients undergoing total shoulder arthroplasty. The maximum temperature and the duration of temperatures greater than the established thresholds for thermal necrosis were documented. The first five arthroplasties were performed without irrigation and were compared with the second five arthroplasties, in which continuous bulb irrigation was used during drilling and reaming. A one-dimensional finite element model was developed to estimate the depth of penetration of critical temperatures into the bone of the glenoid on the basis of recorded surface temperatures.

The first hypothesis was supported by the recording of maximum surface temperatures above the 56°C threshold during reaming in four of the five arthroplasties done without irrigation and during drilling in two of the five arthroplasties without irrigation. The estimated depth of penetration of the critical temperature (56°C) to produce instantaneous osteonecrosis was beyond 1 mm (range, 1.97 to 5.12 mm) in four of these patients during reaming and one of these patients during drilling, and two had estimated temperatures above 56°C at 3 mm. 

The second hypothesis was supported by the observation that, in the group receiving irrigation, the temperature exceeded the critical threshold in only one specimen during reaming and in two during drilling. The estimated depth of penetration for the critical temperature (56°C) did not reach a depth of 1 mm in any of these patients (range, 0.07 to 0.19 mm).

They concluded that temperatures sufficient to induce thermal necrosis of glenoid bone can be generated by glenoid preparation in shoulder arthroplasty in vivo. Frequent irrigation may be effective in preventing temperatures from reaching the threshold for bone necrosis during glenoid preparation.

Another recent article is relevant, Thermal and Cutting Dynamics of New and Used Glenoid Reamers During Total Shoulder

These authors suggest that inaccurate reaming and thermal osteonecrosis from heat generated during the reaming process may contribute to TSA failure by creating a suboptimal bone-implant interface. They investigated the differences in depth penetration and heat generation of used community glenoid reamers in comparison to previous unused reamers.

They used a MTS Servohydraulic machine to test new and used community glenoid

reamers by applying the clinically relevant force of 54.7 N over a defined time. The depth of

penetration was measured via the MTS machine and the thermal profile was obtained via an

infrared camera. The used reamers were then set by the MTS machine to reach the same depth as the new reamers for all respective sizes while recording the force differential generated and capturing the thermal profile. 

At a constant force and time, the new reamers penetrated a greater depth (4.18 mm ± 2.17 mm) than the community used reamers (0.41 mm ± 0.22 mm), a difference of 3.80 mm ((95% CI, 2.23 mm to 5.31 mm), p < 0.001) without generating temperatures above 50°C. 

When programmed to reach the same average depth as the new reamers of equivalent sizes, the community reamers generated more heat on average (50.02 °C ± 2.88 °C), a difference of 5.98 °C ((95% CI, 3.40 to 8.53), p < 0.001). The used reamers on average also required 218.20 N more force than the new reamers (54.71 N ± 28.69 N) to reach the same depth, with the medium (303.47 N ± 96.71 N) and large (261.72 N ± 55.28 N) reamers specifically requiring the largest amount of force.

They concluded that the sharpness of glenoid reamers varies in the community. In order to reach the necessary depth for adequate fixation of implants, orthopedic surgeons may be required to exert a substantially larger force when using dulled reamers in comparison to sharp reamers. As a consequence, the heat generated could increase the risk of thermal osteonecrosis contributing to glenoid loosening.

Comment: These articles point to the ability of reaming to generate bone-killing levels of heat in the glenoid bone. This heat may interfere with the healing of bone in a ream and run procedure and with the stability of fixation in total shoulder arthroplasty.

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 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).

Glenoid retroversion, "correction" and perforation - what matters?

Risk of Perforation Is High During Corrective Reaming of Retroverted Glenoids: A Computer Simulation Study

These authors used a computer simulation to examine the effects of anterior glenoid reaming to  address glenoid retroversion in 71 shoulders having anatomic shoulder arthroplasty for arthritis with a biconcave retroverted glenoids with posterior subluxation of the humeral head.

Forty-four of 71 glenoids (62.5%) had < 25° of native retroversion. 

Anatomic glenoid implants were then virtually implanted using three-dimensional CT software that allows for preoperative shoulder arthroplasty planning to correct native retroversion to 15° or 10° of retroversion using both a central peg with an inverted triangle peg configuration or a keel. 

They found that correction to 15° of retroversion required 5±3 mm of reaming, and correction to 10° of retroversion required 8±3 mm of reaming to obtain at least 80%seating. 

Peripheral peg perforation with correction to 15° occurred in 15 of 27 (56%) glenoids with > 25° of retroversion compared with 10 of 44 (23%) of glenoids with < 25° of retroversion. There was no difference in perforation with keeled components. 

When correcting to 15°, glenoids with higher native version (> 25°) had a greater risk of poor bone quality support (10 of 27 [37%]) when compared with glenoids with less version (four of 44 [9%].  

Comment: When dealing with a retroverted glenoid

there are several options for positioning an anatomic glenoid.

(1) Insert in anatomic version without reaming, leaving the posterior aspect of the component unsupported

(2) Reaming in anatomic version, sacrificing anterior glenoid bone and reducing the quality of bone supporting the component

(3) Inserting a technically challenging posterior bone graft to support the component

(4) Using a posteriorly augmented polyethylene component

accepting the risk of increased posterior bone loss should the component fail.

(5) Avoiding excessive reaming 

and instead, inserting the component without specific attempt to change glenoid version, reaming only enough to produce a single concavity.

 Then using an anteriorly eccentric humeral head

and rotator interval plication 

to manage any tendency for posterior instability as shown below

While (as shown above) there can be some peg perforation, but this has not been associated with component failure using this method.

The results of this approach are described in 

Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty? and below.

This remains our preferred method for managing the B2 glenoid.

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How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages   arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Preserving glenoid bone in total shoulder arthroplasty

Short-term radiographic results of a cemented polyethylene keeled glenoid component with varying backside radiuses of curvature

These authors analyzed the radiographic results of a cemented all-polyethylene keeled glenoid component available in different sizes and multiple backside radiuses of curvature implanted in 118 shoulders.

A type A1 glenoid was found in 28 shoulders, an A2 in 51, a B1 in 24, a B2 in 18, and a B3 in 4. The surgical technique included measuring the curvature of the arthritic glenoid and selecting a backside curvature that closely matched it so that minimal glenoid reaming was required.

Mean follow-up was 38 months. The mean radiolucent line score after surgery was 0.54 points and 90% had no or only 1 radiolucent line. At the final follow-up, the mean score was 1.06 points (range, 0-3 points) and 74% had no or only 1 radiolucent line. The radiolucent line score increased significantly over time. No component was at risk for loosening. No correlation was found between patient age, sex, hand dominance, glenoid morphology, or fatty infiltration of the rotator cuff muscles and the occurrence of radiolucent lines.

Comment: These authors have advocated an approach to glenoid arthroplasty that minimizes glenoid reaming and maximizes preservation of the subchondral glenoid bone.

It is interesting, however, that they do not describe how they managed the important problem of glenoid retroversion and biconcavity for the type "B" glenoids included in this study.

In performing prosthetic glenoid arthroplasty, our goal (like that of theses authors) is to minimize the amount of glenoid bone removed, striving to preserve the subchondral bone. We do not attempt to "correct" glenoid retroversion by eccentric reaming

In the presence of retroversion and a biconcave glenoid, we adjust the angle of the reamer to preserve glenoid bone stock while still providing a good match of the reamed glenoid bone to the backside of the glenoid component.

See this link:  

Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

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Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

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 as well as the 'ream and run essentials'

Glenoid reaming, why we don't use a guide wire.

While some surgeons try to use a guide wire in an attempt to 'correct' glenoid retroversion (as shown in the upper figure copyrighted by Steve Lippitt ) we use a nubbed reamer that allows us to adjust the angle of the reamer to minimize the bone removal in conservatively reaming the glenoid to a single concavity (lower figure).

Below is an example of a two year followup of a ream and run procedure in which the glenoid was reamed conservatively without specific attempt to change version.

An anteriorly eccentric humeral head was used to achieve centering in the reamed glenoid as shown below.

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Use the "Search" box to the right to find other topics of interest to you.

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