Although the data suggest that PIPJ pyrocarbon implants deliver excellent in vivo durability and biomechanics, there are no convincing data thus far to support the use of this prosthesis over the traditional silicone implant for the osteoarthritic PIPJ. Because the pyrocarbon implant is a relatively new technology, it has not been well investigated. There are currently 6 English language publications presenting short-term outcomes after pyrocarbon implant PIPJ arthroplasty.17–21, 33
() Most outcomes studies of the short-term use of pyrocarbon implants for the PIPJ have shown high patient satisfaction, but nearly all studies have described some radiographic loosening of the implant and/or high rate of clinical complications. There are currently only 2 published reports evaluating intermediate-term outcomes after pyrocarbon PIPJ arthroplasty8, 22
(). Bravo et al.8
retrospectively studied a total of 50 implants in 35 patients with a minimum follow-up period of 27 months in 2007. In that study, decreased pain scores on a visual analog scale (VAS), improved grip and pinch, and subjective patient satisfaction (80%) were noted. The authors, however, showed that additional procedures were needed in 28% of joints, including 4 that were revised for instability (although dislocation was not specifically reported) and 4 that were revised for loosening of the implants. The authors also noted that 40% of the implants showed radiographic migration at the time of the final evaluation.
Published Reports on PIPJ Arthroplasty with Pyrocarbon Implants
In 2011, Sweets et al.22
presented minimum 2 year follow-up data of a total of 31 implants in 17 patients with an average follow-up of 55 months, which can be comparable to our data because of use of the MHQ. The average VAS score for pain was 3/10 and satisfaction averaged 3.4 points on a 5-point Likert scale; 12 of 17 patients stated that they would repeat the surgery. However, the arc of motion of the PIPJ decreased from 57° preoperatively to 31° (p
< 0.05) postoperatively, when the involved hand was compared with the noninvolved hand at final follow-up all domains of the MHQ showed significant poorer scores, except Aesthetics. The authors also noted a high rate of complications, including joint contracture in 20 joints, subsidence and loosening in 15 joints, squeaking in 11 joints, dislocation in 5 joints, implant fracture in 1 joint, and a reoperation rate of 19%. Therefore, the authors concluded that pyrocarbon implant arthroplasty for PIPJ had a high complication rate, poor outcomes, and variable patient satisfaction, and they stopped performing this procedure.
Our study also noted a higher incidence of complications (43%) compared to our short-term result, including dislocation in 7 joints. One reason for the high complication rate in our series may be the high proportion of index and long finger arthroplasties; all implant-related complications were observed in these 2 fingers. The index and long fingers require stability for fine pinch, and this functional characteristic may overload the implant and cause a high rate of implant-related complications, compared to ring and small fingers. Radiographic analysis demonstrated high frequency of implants loosening (57%). Compared to the silicone implant, the rate of the dislocation of pyrocarbon implant (33%) is almost the same as the rate of fracture (including suspected fractures) of the silicone implant (30%).10
Additionally, radiographic changes in both silicone and pyrocarbon implants are frequently seen. As to silicone PIPJ arthroplasty, Adamson et al.34
reported sclerosis around 43% of implants, and Ashworth et al.3
found sclerosis in 78% of cases and bony resorption in 12% of cases at long-term follow-up (mean ≥ 5.8 years). In pyrocarbon implants, radiographic signs of loosening and/or migration of the implant can be seen in 40–62% of the joints at intermediate-term follow-up (> 2 years).8, 22
The incidence rate of radiographic changes after pyrocarbon PIPJ arthroplasty may further increase with an additional follow-up time.
Despite these complications, patients are generally were satisfied. MHQ scores compared pre- and postoperatively in the involved hands, showed large effect size for Satisfaction. This result is most likely linked to large effect size in the Pain domain as well. The domains of Work and Aesthetics, showed lower effect size, which indicate that patients’ hands are still low functioning and their appearances are not ideal. Sweets et al reported that 12 of their 17 patients would undergo PIPJ pyrocarbon arthroplasty again, which points to high patient satisfaction. However, when the involved and noninvolved hands were compared, patients were significantly less satisfied with the involved hand.22
Based in part on these poor results and on the number and severity of complications, Sweets et al. opted to discontinue use of the pyrocarbon implant for PIPJ arthroplasty. We also found a high rate of complications, but high patient satisfaction and the repeated request for this type of implant prompted us to continue its use. In both short- and intermediate-term result studies, common findings are significant pain relief, high patient satisfaction, and high rates of complications. Additionally, radiographic findings reveal a higher rate of loosening with migration of the implants at intermediate-term follow-up compared to short-term results. The manufacturer initially stated that the pyrocarbon implant had the potential for bony ingrowth, but recent studies have confirmed that no bony ingrowth occurs between pyrocarbon and the surrounding bone. This indicates that the surrounding bone does not form a stable interface with these implants, and number of complications related to implant loosening may increase over the time. Biomaterial properties research aimed at achieving osteointegration may solve the loosening problem associated with pyrocarbon, given that the surface replacement concept for the current PIPJ implant design appears to be a sensible approach.
Arthroplasty of the PIPJ with a pyrocarbon implant seems to be an effective way of reducing pain without sacrificing AAM. Despite a high rate of complications, patients in our series were generally satisfied. At our center we attribute this to performing the procedure only on self-selecting patients who have suffered with painful hand arthritis for many years, sometimes decades. Patients are also well prepared for the lengthy recovery and possible complication.
Long-term outcomes studies in this field are still limited, and it is difficult to conclude whether pyrocarbon PIPJ arthroplasty is warranted over other PIPJ arthroplasties, or even PIPJ fusion. Long-term studies comparing the outcomes of index and long finger arthroplasties versus ring and small finger arthroplasties may be beneficial in light of the characteristic differences between these 2 groups. Further decision-making analysis to compare pyrocarbon implants and other implants, and PIPJ arthroplasty and fusion may help surgeons to select the appropriate operative procedure.