Shoulder arthroplasty using a pyrocarbon articulating surface has attracted the attention of surgeons and implant companies. We reviewed a dozen articles on the clinical application of pyrocarbon hemiarthroplasty.
Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results These authors reviewed 12 studies with a total of 536 patients having pyrocarbon hemiarthroplasty. Radiographically, 22.8% of patients (n = 536, 8 studies) 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, whereas 0.7% had an increase in tuberosity thickness. Across all studies, there was an 8.6% complication rate, with the most common cause being glenoid erosion (2.6%, n = 14). There was an overall 7.7% revision rate (n = 41), with 63% of revisions (n = 26) undergoing conversion to reverse or total shoulder arthroplasty. The reasons for revision included glenoid erosion, subscapularis failure, periprosthetic fracture, glenoid loosening, instability, subluxation, infection, greater tuberosity fracture, stiffness, pain, impingement, rotator cuff tear, and implant breakage.
Comparing revision rates and survival of pyrocarbon and non-pyrocarbon heads in total- and hemi- shoulder arthroplasty found that 6 of 47 metal hemiarthroplasties were revised while 1 of 43 pyrocarbon hemiarthroplasties were revised. The reasons for revision were not provided. It is of note, as shown below, that the followup period for the non-pyrocarbcn (metal) humeral hemiarthroplasties was longer than for the pyrocarbon humeral heads and that most of the revisions for the metal heads occurred after 7 years; 7 year data was not available for the pyrocarbon heads.
In total, 5 revisions were performed in the PyCHA group, with patients ranging in age from 37 to 66 years. The time from index surgery to revision ranged from 0.03 to 3.58 years. Three patients underwent revision owing to ‘‘overstuffing’’ of the glenohumeral joint due to oversized implants, and the other 2 patients underwent revision owing to rotator cuff failure.
The differences in the total OSS and the pain and function subcategory scores were not statistically significant between the PyCHA and HA groups.
The hypothesis of a lower revision rate and superior OSS in the PyCHA group compared with the HA and aTSA groups was not supported.
Pyrocarbon humeral heads for hemishoulder arthroplasty grant satisfactory clinical scores with minimal glenoid erosion at 5-9 years of follow-up These authors retrieved the records of 45 consecutive patients who underwent HSA with pyrocarbon humeral heads from 2013 to 2017.
Glenoid erosion at two years and five years after surgery are shown below.
Glenoid erosion was not associated with clinical outcome
From the examples shown in the article, there was a consistent problem with overstuffing.
and bone resorption (adaptive changes) in the metaphysis.
Short-term outcomes and survival of pyrocarbon hemiarthroplasty in the young arthritic shoulder
Because of the fragility of pyrocarbon a metal plate (lower row) is used to obviate the risk of fracture of the unprotected pyrocarbon head (upper row)
This results in a thicker head than that for a metallic head of the same diameter of curvature.
The authors concluded that “the severity of glenoid bone erosion or the association with glenoid reaming does not affect functional outcomes and failure risk. By contrast, nonanatomic reconstruction of the proximal humerus after HA-PYC (see below) is not rare (one-third of the cases) and is associated with lower functional outcomes, as well as higher risks of complications (subscapularis insufficiency and/or symptomatic glenoid erosion) and revision (see below). Surgeons should be aware of the increased thickness of the pyrocarbon heads, related to the addition of a metallic plate (+1.5 mm in thickness) under the bearing surface to prevent any breakage of the pyro- carbon head plus the void (+0.5 mm) needed to accommodate the double Morse taper.”
Survivorship of shoulder arthroplasty in young patients with osteoarthritis: an analysis of the Australian Orthopaedic Association National Joint Replacement Registry These authors studied patients aged <55 years, of which 70 (4.5%) were stemmed hemiarthroplasty with a metal head (HSMH) and 159 (10.2%) were stemmed hemiarthroplasty with a pyrocarbon head (HSPH). Glenoid erosion was the most common cause of revision for HSMH (50%). Instability/dislocation was the leading cause of revision for HSPH (28.6%).
Pyrocarbon hemiprostheses show little glenoid erosion and good clinical function at 5.5 years of follow-up These authors performed a single-center consecutive cohort study of 31 of 34 patients (91%) who underwent pyrocarbon hemiarthroplasty (PyC HA) between September 2013 and June 2018. In 11 of these patients, concentric glenoid reaming was additionally performed. The mean follow-up period was 5.5 years (range, 3.5-7 years). . Anteroposterior radiographs were analyzed according to an established method by 2 independent observers: 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. The distance between these 2 lines was measured. Measurements were scaled using the known diameter of the implanted humeral head component.
Mean medial glenoid erosion measured 1.4 mm at an average of 5.5 years of follow-up. In the first year, 0.8 mm of erosion was observed, significantly more than the average erosion per year of 0.3 mm (P < .001).
Mean erosion per year was 0.4 mm in patients with glenoid reaming vs. 0.2 mm in those without reaming (P = .09).
The prosthesis survival rate was 100%.
There was no correlation between erosion and change in Constant score (r = 0.06) and a weak correlation (r = 0.37) between erosion and pain improvement (P = .039).
In this study there were some examples of overstuffing as shown below.
Pyrocarbon Hemi-Shoulder Arthroplasty Provides Satisfactory Outcomes Following Prior Open Latarjet
These authors reviewed 9 shoulders with arthritis after previous Latarjet procedures that was treated with a pyrocarbon hemiarthroplasty.
One shoulder required conversion to reverse shoulder arthroplasty, 3 years after HSA. The remaining 8 shoulders were assessed at 6.1 years after the index HSA. Glenoid erosion only progressed in 1 shoulder from mild to moderate. The Constant score was 79.6, pain on VAS was 1.0, and SSV was 80.0. The active forward elevation improved from 96 degrees to 151 degrees.
As before, overstuffing was observed.
Pyrolytic carbon head shoulder arthroplasty: CT scan glenoid bone modeling assessment and clinical results at 3-year follow-up these authors reported the radiological glenoid modifications and clinical outcomes in 41 patients at 3 years mean follow-up of hemi shoulder arthroplasty (HA) with pyrocarbon (PYC) humeral head at an average follow-up of 36.3 months. No glenoid reaming was performed. Preoperative and postoperative computed tomography scans at the last follow-up were performed to achieve 3-dimensional reconstructions of the scapulae. Deformities of the glenoid surface were analyzed as a distance differential between postoperative and preoperative to investigate potential bone remodeling vs. glenoid erosion.
Ten of the 13 patients with posterior head subluxation had recentered the humeral head.
Glenoid wear was less than 0.6 mm at 3 years mean follow-up. The authors reported no revisions
Mean humeral head center of rotation (COR) deviation was 2.8 ± 1.1 mm. Eight patients had excessive COR deviation (>3 mm) in superior and medial direction. Reasons for these nonanatomical reconstructions were: oversized implant for 1 patient; inadequate cut (insufficient or vertical) for 7. In addition, 3 other patients had an oversized implant without affecting COR. These 8 patients presented no complications at the last follow-up.
These authors analyzed data from the Australian Orthopaedic Association National Joint Replacement Registry for patients aged <55 years who had undergone a primary shoulder replacement for osteoarthritis from April 16, 2004, to December 31, 2019: 163 were pyrocarbon hemi-resurfacing 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. No pyrocarbon hemi-resurfacing cases were revised for glenoid erosion.
In male patients, pyrocarbon humeral resurfacing had a lower cumulative percentage of revision compared with metal stemmed hemiarthroplasty
Fracture of pyrocarbon humeral head resurfacing implant: a case report
The authors report a case of a pyrocarbon humeral head resurfacing implant fracture, occurring 6 years after its implantation, without any obvious trauma or dislocation.
B2 and B3 glenoid osteoarthirtis: outcomes of corrective and concentric (C2) reaming of the glenoid combined with pyrocarbon hemiarthroplasty
These authors hypothesized that corrective and concentric reaming of the glenoid associated with pyrocarbon hemiarthroplasty (HA-PYC) could improve the centering of the humeral head and decrease the risk of persistent painful glenoid erosion in 41 shoulders of young and active patients with B2 and B3 glenoids. At a mean follow-up of 4.5 years the prosthesis survival was 95% (39 of 41). No patient has been reoperated for painful glenoid erosion. The mean glenoid retroversion decreased from 17.1 degrees preoperatively to 8.3 degrees at last follow-up with improvement in humeral alignment with the glenoid from 59.9% to 50.3%. The humeral head was recentered on the glenoid surface in 97%. CT scan measurements showed that the average total medialization was 3.7 mm due to reaming and 1.7 mm due to erosion). The adjusted Constant Score increased from 43% to 97% and the Subjective Shoulder Value from 38% to 84% Overall, 84% of active patients returned to work, and all patients returned to sports.
At a mean follow-up of 4.5 years, the prosthesis survival rate was 95% (39/41), and no patient has been reoperated for painful glenoid erosion. Two shoulders required revision to reverse total shoulder arthroplasty because of subscapularis insufficiency.
The authors caution that there is a risk of overstuffing the GH joint with HA-PYC because of the presence of a metallic tray under the pyrocarbon head that increases the global thickness of the humeral head by about 2 mm.
Please join us for the AAOS Infection course!!!
