However glenoid wear can occur after hemiarthroplasty. In an effort to reduce wear, interest has been expressed in a pyrocarbon articular surface as an alternative to chrome cobalt.
Pyrocarbon is a form of carbon that is manufactured through a high-temperature pyrolysis process in which the organic material is heated in the absence of oxygen. This material is known for its strength, smoothness, hardness, and resistance to wear and corrosion. Depending on the loading environment, pyrocarbon is reported to have a lower coefficient of friction (0.01 to 0.1) than chrome cobalt (0.1 to 0.4). The reduced friction may be due to:
(1) pyrocarbon's minimal surface roughness resulting from its highly ordered crystalline structure; chrome cobalt has a relatively rougher surface compared to pyrocarbon.
(2) Pyrocarbon exhibits better boundary lubrication properties in comparison to chrome cobalt. Boundary lubrication refers to the mechanism in which the surfaces are self-lubricated by a very thin film - ranging from a few molecular layers to a few micrometers - consisting of molecules adhering to the surface that minimize friction. Chrome cobalt does not possess the same inherent self-lubricating properties as pyrocarbon, but rather relies more on fluid-film lubrication rather than boundary lubrication.
The smoothness and boundary lubrication properties of pyrocarbon may provide advantages in reducing glenoid wear and the inflammation that can result from wear particles. (see In vitro comparison of wear characteristics of PyroCarbon and metal on bone: Shoulder hemiarthroplasty)
Below is a two year radiographic followup of a pyrocarbon head on a short stem as reported in Pyrolytic carbon humeral head in hemi-shoulder arthroplasty:preliminary results at 2-year follow-up
Here are some receond reports of the use of pyrocarbon humeral heads:
Pyrolytic carbon humeral head in hemi-shoulder arthroplasty: preliminary results at 2-year follow-up 2018.
Pyrolytic carbon humeral head in hemi-shoulder arthroplasty: preliminary results at 2-year follow-up 2018.
At the 2-year follow-up, 50 glenoids (86%) showed no progression of erosion compared with their preoperative status whereas erosion was noted in 8 glenoids (14%).
Fracture of pyrocarbon humeral head resurfacing implant: a case report 2020.
Fracture of pyrocarbon humeral head resurfacing implant: a case report 2020.
"Our observation put into question the use of pyrocarbon as a humeral head resurfacing implant. The material seems to be too fragile to be used as a resurfacing implant and cannot achieve fixation of the implant to bone."
Promising results after hemi-shoulder arthroplasty using pyrolytic carbon heads in young and middle-aged patients 2021.
Of 16 patients having an average 2 year followup, the survival rate was high (94.1%). One periprosthetic fracture occurred as the only complication during follow-up. Radiographs showed glenoid erosion in one case and subacromial space reduction in two cases.
Pyrocarbon Arthroplasty Implants in the Upper Extremity: A Systematic Review of Outcomes and Pooled Analysis of Complications 2021.
Promising results after hemi-shoulder arthroplasty using pyrolytic carbon heads in young and middle-aged patients 2021.
Of 16 patients having an average 2 year followup, the survival rate was high (94.1%). One periprosthetic fracture occurred as the only complication during follow-up. Radiographs showed glenoid erosion in one case and subacromial space reduction in two cases.
Pyrocarbon Arthroplasty Implants in the Upper Extremity: A Systematic Review of Outcomes and Pooled Analysis of Complications 2021.
Shoulder arthroplasty with pyrocarbon complication rate 13%.
Short-term outcomes and survival of pyrocarbon hemiarthroplasty in the young arthritic shoulder 2022.
Short-term outcomes and survival of pyrocarbon hemiarthroplasty in the young arthritic shoulder 2022.
At a mean followup of 33 months, the rate of survival of the HA-PYC prosthesis among 64 shoulders was 92%. Revision was performed in 5 patients: 1 conversion to TSA and 4 conversions to reverse shoulder arthroplasty. The severity of preoperative and postoperative glenoid wear had no influence on the functional results. Nonanatomic reconstruction of the proximal humerus (center of rotation of the prosthesis > 3 mm from the anatomic center) occurred in 29% (18 of 62 patients) and was associated with significantly lower functional and subjective results, more complications (subscapularis insufficiency and/or symptomatic glenoid erosion), and a higher risk of revision. The additional 1.5-mm thickness of the metal disc under the pyrocarbon head was found to be the main reason for overstuffing of the prosthetic head.
Mid-term outcomes of pyrolytic carbon humeral resurfacing hemiarthroplasty compared with metal humeral resurfacing and metal stemmed hemiarthroplasty for osteoarthritis in young patients: analysis from the Australian Orthopaedic Association National Joint Replacement Registry 2022.
The authors analyzed 393 primary shoulder procedures, of which 163 were pyrocarbon hemi-resurfacing (unstemmed) procedures,
163 were metal hemi-resurfacing procedures, and 67 were metal stemmed hemiarthroplasties. The cumulative percentage of revision at 6 years was 8.9% for pyrocarbon hemi-resurfacing, 17.1% for metal hemi-resurfacing, and 17.5% for metal stemmed hemiarthroplasty. Pain, prosthesis fracture, and infection were the key reasons for revision of the pyrocarbon resurfacing hemiarthroplasty.
Short to Early-Mid Term Clinical Outcomes and Survival of Pyrocarbon Shoulder Implants: A Systematic Review and Meta-Analysis 2023.
Mid-term outcomes of pyrolytic carbon humeral resurfacing hemiarthroplasty compared with metal humeral resurfacing and metal stemmed hemiarthroplasty for osteoarthritis in young patients: analysis from the Australian Orthopaedic Association National Joint Replacement Registry 2022.
The authors analyzed 393 primary shoulder procedures, of which 163 were pyrocarbon hemi-resurfacing (unstemmed) procedures,
163 were metal hemi-resurfacing procedures, and 67 were metal stemmed hemiarthroplasties. The cumulative percentage of revision at 6 years was 8.9% for pyrocarbon hemi-resurfacing, 17.1% for metal hemi-resurfacing, and 17.5% for metal stemmed hemiarthroplasty. Pain, prosthesis fracture, and infection were the key reasons for revision of the pyrocarbon resurfacing hemiarthroplasty.
Short to Early-Mid Term Clinical Outcomes and Survival of Pyrocarbon Shoulder Implants: A Systematic Review and Meta-Analysis 2023.
Two year survivorship of 92%.
Short-term outcomes following 159 stemmed pyrolytic carbon shoulder hemiarthroplasties and how they compare with conventional hemiarthroplasties and total shoulder arthroplasties in patients younger than 60 years with osteoarthritis: results from the New Zealand National Joint Registry 2023.
Short-term outcomes following 159 stemmed pyrolytic carbon shoulder hemiarthroplasties and how they compare with conventional hemiarthroplasties and total shoulder arthroplasties in patients younger than 60 years with osteoarthritis: results from the New Zealand National Joint Registry 2023.
Among patients aged <60 years with shoulder osteoarthritis, 48 underwent pyrocarbon hemiarthroplasty compared with 150 who underwent conventional hemiarthroplasty. There was no significant difference in revision rates or clinical outcomes between the groups.
Survivorship of shoulder arthroplasty for young patients with osteoarthritis: An Analysis of the Australian Orthopaedic Association National Joint Replacement Registry 2023
For stemmed hemiarthroplasty with a metal head, the cumulative revision rates at 2 years and 5 years were 7.4% and 16.7%. Glenoid erosion was the most common cause for revision.
For stemmed hemiarthroplasty with a pyrocarbon head, the cumulative revision rates at 2 years and 5 years were 3.5% and 8.9%. Instability was the most common cause for revision.
Pyrocarbon hemiprostheses show little glenoid erosion and good clinical function at 5.5 years of follow up 2023.
31 shoulders underwent PyC hemiarthroplasty; 11 also had concentric glenoid reaming. The mean follow-up was 5.5 years. AP x-rays were analyzed: A line parallel to the superior and inferior glenoid rim was translated to the most medial point of the glenoid surface. A further parallel line was placed on the spinoglenoid notch and the distance between the two lines was measured.
Measurements were scaled using the known diameter of the implanted humeral head component.
The mean medial glenoid erosion was 1.4 mm over 5.5 years. In the first year there was 0.8 mm of erosion, significantly more than the average erosion per year of 0.3 mm. Mean erosion per year of patients with glenoid reaming was 0.4 mm, without reaming 0.2 mm. Prosthesis survival rate was 100%. There was a weak correlation between erosion and pain improvement and no correlation between erosion and delta Constant score.
Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results 2023.
12 studies (536 patients with pyrocarbon hemiarthroplasties) were reviewed with a minimum 2-year follow-up. Radiographically, 22.8% of patients had evidence of glenoid erosion, 10.4% had changes in implant positioning, and 9.9% had tuberosity thinning. In addition, 1.5% of patients had radiographic subacromial space reduction. There was an 8.6% complication rate, with the most common cause being glenoid erosion. There was an overall 7.7% revision rate, with 63% of revisions undergoing conversion to reverse or total shoulder arthroplasty.
Comment: Pyrocabon humeral heads are more expensive than chrome cobalt heads due to the unique properties and specialized manufacturing processes. Chrome cobalt heads have a long and well-established track record with low revision rates. Comparing the clinical value of pyrocarbon to chrome-cobalt will require randomized trials that control for surgeon expertise, patient characteristics and shoulder characteristics as well as knowledge of the costs of the two systems. The reason randomization is essential lies in the fact that without it,
Survivorship of shoulder arthroplasty for young patients with osteoarthritis: An Analysis of the Australian Orthopaedic Association National Joint Replacement Registry 2023
For stemmed hemiarthroplasty with a metal head, the cumulative revision rates at 2 years and 5 years were 7.4% and 16.7%. Glenoid erosion was the most common cause for revision.
For stemmed hemiarthroplasty with a pyrocarbon head, the cumulative revision rates at 2 years and 5 years were 3.5% and 8.9%. Instability was the most common cause for revision.
Pyrocarbon hemiprostheses show little glenoid erosion and good clinical function at 5.5 years of follow up 2023.
31 shoulders underwent PyC hemiarthroplasty; 11 also had concentric glenoid reaming. The mean follow-up was 5.5 years. AP x-rays were analyzed: A line parallel to the superior and inferior glenoid rim was translated to the most medial point of the glenoid surface. A further parallel line was placed on the spinoglenoid notch and the distance between the two lines was measured.
Measurements were scaled using the known diameter of the implanted humeral head component.
The mean medial glenoid erosion was 1.4 mm over 5.5 years. In the first year there was 0.8 mm of erosion, significantly more than the average erosion per year of 0.3 mm. Mean erosion per year of patients with glenoid reaming was 0.4 mm, without reaming 0.2 mm. Prosthesis survival rate was 100%. There was a weak correlation between erosion and pain improvement and no correlation between erosion and delta Constant score.
Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results 2023.
12 studies (536 patients with pyrocarbon hemiarthroplasties) were reviewed with a minimum 2-year follow-up. Radiographically, 22.8% of patients had evidence of glenoid erosion, 10.4% had changes in implant positioning, and 9.9% had tuberosity thinning. In addition, 1.5% of patients had radiographic subacromial space reduction. There was an 8.6% complication rate, with the most common cause being glenoid erosion. There was an overall 7.7% revision rate, with 63% of revisions undergoing conversion to reverse or total shoulder arthroplasty.
Comment: Pyrocabon humeral heads are more expensive than chrome cobalt heads due to the unique properties and specialized manufacturing processes. Chrome cobalt heads have a long and well-established track record with low revision rates. Comparing the clinical value of pyrocarbon to chrome-cobalt will require randomized trials that control for surgeon expertise, patient characteristics and shoulder characteristics as well as knowledge of the costs of the two systems. The reason randomization is essential lies in the fact that without it,
(1) better surgeons, high volume surgeons, or surgeons with conflicts of interest might exert a selection bias on which patients received pyrocarbon
(2) healthier, better informed or socio-economically advantaged patients may be more likely to receive pyrocarbon.
These and other important variables are essentially impossible to control for without randomization.
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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).
Follow on twitter: https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
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).
