Pyrocarbon unipolar radial head prosthesis: clinical and radiologic outcomes at long-term follow-up

The use of pyrocarbon as a bearing surface in shoulder arthroplasty: A systematic review and meta-analysis

Background

Pyrocarbon has been trialed as an alternative bearing surface to metal for young active patients with glenohumeral joint arthritis. The aim of this study was to systematically review and summarize the available evidence on reported outcomes of pyrocarbon implants in shoulder arthroplasty.

Methods

A systematic review was conducted according and reported according to standardized guidelines. Patient demographics, complications, implant survivorship and patient-reported outcome measures were extracted and included in the quantitative analysis. Outcome data was summarized with weighted mean differences and proportions.

Results

Fifteen studies were included with 904 patients and a median follow-up of 38 months. The pooled mean range of motion improvement was 43.9 degrees (95% confidence interval [95% CI] 36.7-51.2) in forward elevation and 24.1 degrees (95% CI 18.4-29.9) in external rotation. Pooled mean Constant Score improvement was 34.7 (95% CI 29.4-40.1) and Subjective Shoulder Value improvement was 40.6 (95% CI 33.4-47.8). The overall pooled re-operation rate was 8.03% (95% CI 5%-12.7%).

Discussion

Pyrocarbon shoulder implants demonstrated improvements in functional outcomes with low revision rates at early- to mid-term follow-up. Further well-designed prospective studies with long-term follow-up are required to verify the safety and efficacy of pyrocarbon implants in shoulder arthroplasty.

Comparative Analysis of Two Hemiarthroplasty Techniques for Symptomatic Distal Radial Ulnar Joint Arthritis

Background  Hemiarthroplasty may be indicated for patients with distal radioulnar joint (DRUJ) arthritis. Recently, the use of the pyrocarbon metacarpophalangeal implant has been proposed as a novel means of treating DRUJ arthritis due to the materials improved mechanical properties and wear characteristics. Purpose  This study compares midterm outcomes of metallic and pyrocarbon hemiarthroplasties for the treatment of symptomatic DRUJ arthritis. Questions of interest included outcomes and complications. Materials and Methods  In total, 32 hemiarthroplasties, 10 metallic and 22 pyrocarbon, were performed between 2010 and 2020 by three surgeons at one tertiary medical center. Patients' retrospective outcomes were extracted from the electronic medical record. Results  Postoperatively, the metallic implant group (mean follow-up: 38 months) demonstrated decreased pain but no changes in range of motion. Comparatively, the pyrocarbon group experienced an improved range of motion and postoperative pain ( p  < 0.05). Radiographic analysis demonstrated 10% of metallic implants and 9% of pyrocarbon implants to have resulted in thinning of the lateral cortex of the radius at the final follow-up. Minor complications in metallic and pyrocarbon implant groups warranting reoperation occurred at rates of 10 and 13.5% while implant failure occurred at a rate of 30 and 18%, respectively. Discussion  Within this study, pyrocarbon implants resulted in significant functional improvement with comparable complication and failure rates to the metallic implant. Long-term stability demonstrated efficacy for both techniques in symptomatic DRUJ treatment. Type of Study/Level of Evidence  Observational Case Series IV.

Plate or Arthroplasty for complex Mason Type-III Radial Head Fractures? Mid-to-long term results from a blinded outcome assessor study

BACKGROUND

The surgical treatment of radial head fractures like Mason type III comminuted radial head fractures is challenging and controversial. Whether to use open reduction and internal fixation (ORIF) or radial head arthroplasty (RHA) as treatment methods is under constant debate.

METHODS

We retrospectively analyzed clinical and radiographic mid- to long-term results of 42 patients with a mean follow-up time of 4.56 years (1.92-7.58 years). Patients were grouped according to fragment numbers and the type of intervention performed (3-4 fragments vs. 4+ fragments; ORIF vs. RHA). At the final follow-up, range of motion (ROM), functional rating scores and subjective pain and function levels were documented by a blinded outcome assessor.

RESULTS

Although minor differences in the mean values were detected when comparing the results of the functional scores, ROM and subjective pain and function levels, only the movement in pronation and supination direction yielded statistically better results in the group of 4+-fragments for the RHA compared to ORIF. However, the 33 % rate of required implant removal amongst the ORIF group should be considered.

CONCLUSIONS

This study provides evidence that 3- and 4-part Mason type III fractures are prone to plate osteosynthesis. In contrast, greater than 4-part fractures can more reliably be treated by replacement. This leads to a proposed increase in fragment numbers to four, where ORIF most likely leads to good clinical results. However, in patients with 4+ fragment patterns, ORIF did not show statistically significantly worse results concerning the collected clinical values. This study supports the use of the ORIF approach to save the radial head.

Stress shielding following radial head arthroplasty: the impact of preoperative bone quality

BACKGROUND

We sought to assess if the medullary diameter to cortical width ratio (MD:CW), canal flair index (CFI), and canal fill (CF) of the proximal radius were associated with the presence of stress shielding (SS) after a MoPyC radial head arthroplasty.

MATERIALS AND METHODS

We conducted a retrospective, international, multicenter (4 centers) study. A total of 100 radial head arthroplasties in 64 women and 36 men with a mean age of 58.40 years ± 14.90 (range, 25.00-91.00) were included. Radiographic measurements, including MD:CW, CFI, CF, and postoperative SS were captured at a mean follow-up of 3.9 years ± 2.8 (range, 0.5-11).

RESULTS

SS was identified in 60 patients. Mean preoperative MD:CW, CFI, and CF were 0.55 ± 0.09, 1.05 ± 0.18, and 0.79 ± 0.11, respectively. The presence of SS was significantly associated with MD:CW (adjusted odds ratio = 13.66; P = .001), and expansion of the stem (adjusted odds ratio = 3.78; P = .001). The amount of the SS was significantly correlated with expansion of the stem (aβ 4.58; P < .001).

CONCLUSIONS

Our study found that MD:CW was an independent risk factor of SS after MoPyc radial head arthroplasty. Autoexpansion of the MoPyc stem significantly increased the risk of SS and its extent. Further studies involving multiple implants designs are needed to confirm the preliminary observations presented in the current study.

Pyrocarbon radial head arthroplasty offers satisfactory clinical and radiological outcomes with low revision rate: A systematic review

INTRODUCTION

Pyrocarbon promises to be an optimal material choice for radial head arthroplasty (RHA) due to an elastic modulus comparable to the radial diaphysis and thus providing higher biocompatibility. Primary objective was to determine the complications and revision rates related to the usage of these prostheses. The secondary objective was to assess the clinical and radiological outcomes of Pyrocarbon RHAs.

HYPOTHESIS

Pyrocarbon RHAs have good clinical and radiological outcomes with low complications and revisions.

METHODS

Ovid MEDLINE and Embase databases were used to search for studies on outcomes and complications of the RHAs using Pyrocarbon radial head prostheses. The systematic review was designed in accordance with the PRISMA guidelines and included studies were appraised using the MINORS tool. Complications and RHA revision rates were assessed. Functional outcomes were reviewed using PROMs (like MEPI, DASH and BMS), post-op range of motion (using goniometer) and grip strength (using the dynamometer). Postoperative radiological outcomes like peri-prosthetic lucency, radial neck osteolysis, radio-capitellar congruence, capitellar erosion, overstuffing/understuffing and osteoarthritis were reported using radiographs.

RESULTS

A total of 12 studies cumulatively reporting 353 patients who underwent Pyrocarbon RHAs were included in the review. The mean age of patients across the studies ranged from 47 to 54 years of which 50.5% were males. The majority of radial head replacements were done for acute trauma (87.5%) with the remainder done for arthritis (1.7%) and trauma sequelae (10.8%). Mean follow-up period in the selected studies ranged from 18 to 110 months with minimum follow-up across all studies being 12 months. Modular Pyrocarbon (MoPyC, Tornier™) was the implant of choice in ten studies while two studies used the Ascension Pyrocarbon radial head (Ascension Orthopaedics™). Ten studies demonstrated mean MEPI ranging from 75.5 to 96. Mean extension deficit ranged from 6 to 19 degrees, mean flexion from 120 to 140 degrees, mean pronation from 71 to 87 degrees and mean supination from 63 to 85 degrees. Relative grip strength ranged from 69 to 96% of the contralateral limb. Revisions due to implant-related reasons (intra-prosthetic dissociation, prosthetic fracture, peri-prosthetic loosening, radio-capitellar subluxation and understuffed/overstuffed elbow) was 6.8% (24/353). Radial stress shielding and peri-prosthetic lucency was reported in 10 to 100% of patients across different studies but symptomatic implant loosening leading to revision remained rare (2%, 7/353). Radio-capitellar congruence was reported in 81% to 100% cases while capitellar erosion ranged from 0% to 89%. Pyrocarbon implants specific complications included head-neck intra-prosthetic decoupling (1.1%) and pyrocarbon head fractures (0.9%). In total, 5.7% cases underwent re-surgery due to non-RHA related reasons.

DISCUSSION

The pyrocarbon RHA shows good functional outcome, range of motion and low revision rates. This aligns with the working hypothesis of this review. However, pyrocarbon radial head implants have implant-specific complications like pyrocarbon radial head fractures and intra-prosthetic decoupling between stem and head. Despite promising in vitro biomechanical properties, capitellar wear is still a common finding with pyrocarbon RHAs. Despite these factors, pyrocarbon radial head implants are a viable option for radial head arthroplasty.

LEVEL OF EVIDENCE

II; Systematic review.

Radial head replacement - A comprehensive review

Background

Radial head fractures represent 1-4% of all adult fractures and 1/3rd of elbow fractures (Kaas et al., 2010). Radial head is an important secondary stabilier of the elbow. The aim of the treatment of radial head fractures is to achieve stability and good functional outcome. Radial head replacement (RHR) is indicated when robust reconstruction and fixation of the fracture fragments is not possible.

Methods

This article explores history and evolution, anatomical considerations, biomechanics, implant designs, indications, surgical outcomes and controversies in radial head replacement based on current evidence.

Results

There is a wide range of RHR designs available without conclusive evidence to support the superiority of one design over the other. Ranges of motion, functional outcomes and complication were comparable among different designs with a high incidence of complications reported in many studies.

Conclusion

RHR remains a good option in unreconstructible radial head fractures, with potential to regain excellent function. It is imperative to continue with the quest to innovate and improve on current designs, to reduce complications in the long term.

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.