Poor results after pyrocarbon interpositional shoulder arthroplasty

Pyrocarbon hemiarthroplasty and the shoulder: biomechanical and clinical results of an emerging treatment option

While shoulder hemiarthroplasty is still used to treat young patients with shoulder pathology, the use of this procedure has substantially declined in recent years due to its significant complication profile. Glenoid wear with arthrosis is one of the major postoperative complications following shoulder hemiarthroplasty, and efforts to prevent this complication led many scientists to explore alternative weight-bearing surfaces on arthroplasty implants to decrease joint wear and improve patient outcomes. Pyrolytic carbon, or pyrocarbon, is a material that has better biocompatibility, survivorship, strength, and wear resistance compared to the materials used in traditional shoulder hemiarthroplasty. Pyrocarbon implants have been used in orthopedics for over 50 years; recently, their utility in shoulder hemiarthroplasty has garnered much interest. The purpose behind the use of pyrocarbon in shoulder hemiarthroplasty is to decrease the risk of progressive glenoid wear, especially in young active patients in whom joint preservation is important. Promising survivorship and outcomes have been demonstrated by recent studies, including limited glenoid wear following pyrocarbon hemiarthroplasty. Nevertheless, these clinical studies have been limited to relatively small case series with limited long-term follow-up. Accordingly, additional research and comparative studies need to be conducted in order to properly assess the therapeutic efficacy and value of pyrocarbon hemiarthroplasty.

Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results

BACKGROUND

Hemiarthroplasty is often considered in the setting of preserved glenoid cartilage given the high risk of revision associated with total shoulder arthroplasty. Pyrocarbon (PyC) has been used as an implant material that theoretically allows for formation of a neo-membrane that would act like cartilage to reduce glenoid wear. The purpose of this study was to evaluate the clinical outcomes, radiographic outcomes, revision rates, and complication rates in the existing literature on shoulder hemiarthroplasty using PyC.

METHODS

The MEDLINE, Embase, and Scopus databases were searched for articles relating to shoulder hemiarthroplasty using the terms "pyrocarbon" or "pyrolytic carbon." Abstracts and articles were screened against predefined inclusion and exclusion criteria, with a minimum of 24 months' follow-up required. Data on patient demographic characteristics, clinical outcome scores, complications, revision rates, and radiographic findings were recorded. Where appropriate, meta-analysis was performed.

RESULTS

Twelve studies were selected for final inclusion, with a total of 536 patients. Among the studies reporting preoperative and postoperative range of motion (ROM), an overall improvement in ROM was observed. The mean Constant score was 70.9 points postoperatively, with a mean improvement of 36.2 points (n = 359, 9 studies). 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.

CONCLUSION

PyC hemiarthroplasty shows overall improvements in ROM and patient-reported outcomes for patients. However, there remains concern for glenoid erosion on radiographic evaluation at minimum 2-year follow-up. Although preliminary studies have shown encouraging results, this systematic review emphasizes the need for longer-term follow-up studies with further radiographic evaluation of the severity of glenoid erosion and the association with functional outcomes and failure risk.

Midterm results of pyrocarbon interposition shoulder arthroplasty: good outcomes after posttraumatic osteonecrosis without malunion of the tuberosities

Background

In vitro data demonstrate the potential benefits of the pyrocarbon as a bearing material against cartilage or bone. And pyrocarbon-free interposition arthroplasty has been used with positive outcomes for over 10 years for hand and wrist joint replacements. This study reports the midterm results of a Pyrocarbon Interposition Shoulder Arthroplasty (PISA) in primary and secondary glenohumeral osteoarthritis and in avascular osteonecrosis.

Methods

This prospective noncontrolled, multicenter study included 67 consecutive patients who underwent PISA in France and Sweden.

Results

A cohort of 48 patients, aged 50 ± 12 years, was available for clinical assessment at a mean follow-up of 67.6 ± 9.3 months. A favorable change was reported with a mean absolute Constant score improvement of 32 ± 20 points. The highest Constant score improvement was observed in patients with avascular osteonecrosis (42 ± 18 points; P ≤ .0001). Between the earliest and the latest follow-up, radiographic analyses revealed only 2 major glenoid erosions and 4 tuberosity thinnings and thus that 86.4% of 44 shoulders remained stable with no or minor radiologic evolutions. The survival rate was 84 % at 65 months of follow-up considering all causes of revision.

Conclusion

The radiographic findings seem to confirm the interest of pyrocarbon in preserving bony surfaces. But the risk of tuberosity thinning suggests considering the use of PISA with caution in most degenerative glenohumeral joint pathologies, although the midterm outcomes highlight PISA as a suitable solution for patients presenting with posttraumatic osteonecrosis without malunion of the tuberosities and with an intact rotator cuff.