Medium-term outcomes of pyrocarbon arthroplasty of the proximal interphalangeal joint

Prosthesis Options for Proximal Interphalangeal Joint Arthroplasty in Osteoarthritis: A Systematic Review and Meta-Analysis

Background: Literature investigating the long-term outcomes of prosthesis options for proximal interphalangeal (PIP) joint arthroplasty is scarce, with most reports combining indications and underlying pathologies in analyses. In this study, we aim to compare silicone, pyrocarbon and metal prostheses in PIP joint arthroplasty for primary degenerative osteoarthritis (OA). Methods: A review of scientific literature published between 1990 and 2021 was conducted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Relevant studies were screened and the appropriate data was extracted. An evaluation of clinical outcomes (range of motion [ROM] and pain), complications (reoperation) and survival rates for each prosthesis was performed. Results: Twelve studies were included for analysis with a total of 412 PIP joints. ROM was 66.6°, 55.8° and 46.4° for metal, silicone and pyrocarbon implants, respectively. Silicone implants had the best pain score on the visual analogue scale (1.2) followed by the pyrocarbon (2.6) and metal (3.9) groups. Complication rates were lowest in silicone implants (11.3%) compared to 18.5% in pyrocarbon and 22.4% in metal prostheses. Survival did not differ significantly amongst the three groups. Conclusions: Our findings suggest that for patients with primary degenerative OA, PIP joint arthroplasty using a silicone prosthesis can provide greater pain relief with lower complication rates compared to other implant options. Level of Evidence: Level III (Therapeutic).

Reported Outcomes and Outcome Measures in Proximal Interphalangeal Joint Arthroplasty: A Systematic Review

Purpose: There is a lack of scientific consensus on the best arthroplasty implant option for proximal interphalangeal joint (PIPJ) arthritis, due to diversity in outcome reporting and measurement methods. The development of a standardized core outcome set (COS) and standard outcome measures could mitigate this issue. This study catalogs the reported outcomes and outcome measures found in PIPJ arthroplasty studies, which can be used in the first step of developing a COS. Methods: A database search of MEDLINE, EMBASE, and Web of Science (January 1, 2010, to March 10, 2021) was performed to retrieve studies that reported outcomes of the 3 most common primary PIPJ arthroplasty implants: silicone, pyrocarbon, and metal-polyethylene. The primary objectives of this study include reported outcomes and outcome measures. Secondary objectives include clinimetric properties of outcome measures, study design, and implant types. Results: Fifty articles met inclusion criteria. Of the included studies, 41 (82%) were case series, 8 (16%) were cohort studies, and 1 (2%) was a randomized control trial. Thirty-three unique outcomes were identified. Fifteen (46%) outcomes were clinician-reported and 26 (79%) were patient-reported. Eighteen unique outcome measures were identified. Of the outcome measures, 15 (83%) were patient-reported, 1 (6%) was clinician-reported, and 2 (11%) were reported by both patients and clinicians. Conclusions: Substantial heterogeneity was found in reported outcomes and outcome measures across studies evaluating PIPJ arthroplasty, impeding knowledge translation. The development of a COS for PIPJ arthroplasty is necessary to help compare and pool data across studies, and advance scientific knowledge.

Proximal interphalangeal joint prosthetic arthroplasty

Surgical treatment of the painful proximal interphalangeal (PIP) joint has evolved considerably over the past century. If arthrodesis has long been the gold standard and remains so for some, prosthesis would meet patient demand: mobility and indolence. Faced with a demanding patient, the surgeon must decide the indication, the type of prosthesis, the approach, the post-operative follow-up, etc. The history of the development of PIP prostheses demonstrates the complexity of the treatment of the destroyed PIP: appearance of prostheses, evolution and sometimes disappearance from the market for commercial reasons or related to complications. The main objective of this conference is to identify the main indications for prosthetic arthroplasties and to describe the various prostheses available on the market.

Pyrocarbon Arthroplasty Implants in the Upper Extremity: A Systematic Review of Outcomes and Pooled Analysis of Complications

BACKGROUND

Growing use of pyrocarbon implants in upper extremity arthroplasty has culminated in a breadth of literature ascertaining outcomes and complications at long-term follow-up. However, at present, the literature remains devoid of studies synthesizing the available evidence for upper extremity surgeons to adequately assess the safety and utility of these implants relative to other available options.

METHODS

A systematic search of the National Library of Medicine, MEDLINE, and Embase databases was performed to determine clinical outcomes and complication and reoperation rates following pyrocarbon arthroplasties in the upper extremity. A breakdown of complication and reoperation rates for each independent joint (shoulder, elbow, wrist, and hand joints), and according to specific causes necessitating surgery, was also compiled.

RESULTS

A comprehensive summary of functional outcomes following upper extremity pyrocarbon arthroplasties is presented. Overall complication and reoperation rates in the hand and wrist were determined to be 28.2 percent and 17 percent, respectively. The proximal interphalangeal joint was associated with the highest complication rate (42.7 percent), followed by carpometacarpal joint (18.8 percent), metacarpophalangeal joint (17.6 percent), wrist (16 percent), elbow (15.7 percent), and shoulder (12.9 percent). In the hand and wrist, major complications included dislocations and subluxations (8.4 percent), stiffness and limited motion (4.4 percent), deformity (3.1 percent), hardware failure (1.9 percent), fractures (1.7 percent), persistent pain (1.7 percent), and infections (0.9 percent).

CONCLUSION

In the absence of large clinical trials, systematic reviews such as these can help inform clinical guidelines and provide practitioners with an evidence-based reference to improve informed consent.

Systematic review of the introduction, early phase study and evaluation of pyrocarbon proximal interphalangeal joint arthroplasty

BACKGROUND

In 2002 a pyrocarbon interphalangeal joint implant was granted Food and Drug Administration approval with limited evidence of effectiveness. It is important to understand device use and outcomes since this implant entered clinical practice in order to establish incremental evidence, appropriate study design and reporting. This systematic review summarised and appraised studies reporting pyrocarbon proximal interphalangeal joint arthroplasty.

METHODS

Systematic review of MEDLINE, EMBASE, SCOPUS, Web of Science, BIOSIS, CINAHL and CENTRAL from inception to November 2020. All study designs reporting pyrocarbon proximal interphalangeal joint arthroplasty in humans were included. Data extracted included information about study characteristics, patient selection, regulatory (gaining research ethics approval) and governance issues (reporting of conflicting interests), operator and centre experience, technique description and outcome reporting. Descriptive and narrative summaries were reported.

RESULTS

From 4316 abstracts, 210 full-text articles were screened. A total of 38 studies and 1434 (1-184) patients were included. These consisted of three case reports, 24 case series, 10 retrospective cohort studies and one randomised trial. Inclusion and exclusion criteria were stated in 25 (66%) studies. Most studies (n = 27, 71%) gained research ethics approval to be conducted. Six studies reported conflicting interests. Experience of operating surgeons was reported in nine (24%) and caseload volume in five studies. There was no consensus about the optimal surgical approach. Technical aspects of implant placement were reported frequently (n = 32) but the detail provided varied widely. Studies reported multiple, heterogenous outcomes. The most commonly reported outcome was range of motion (n = 37).

CONCLUSIONS

This systematic review identified inconsistencies in how studies describing the early use and update of an innovative procedure were reported. Incremental evidence was lacking, risking the implant being adopted without robust evaluation. This review adds to evidence highlighting the need for more rigorous evaluation of how implantable medical devices are used in practice following licencing.

Rehabilitation after proximal interphalangeal joint replacement: A structured review of the literature

Proximal interphalangeal (PIP) joint arthroplasty is an unsolved biomechanical challenge despite advances in materials and new implant designs. This leads to a high rate of complications. Moreover, there is heterogeneity in postoperative management according to the literature. The present structured review examined the therapeutic strategies utilized by physiotherapists to restore a functional finger chain and prevent postoperative complications following PIP joint replacement. Patients undergoing primary total PIP joint arthroplasty of the index, ring, middle or little finger were included. Articles published from 2008 onwards, in French or English, and reporting on PIP joint replacement and postoperative management, were included. Therapeutic strategies were organized according to the surgical approach. Details of splint strategies, mobilization and muscle strengthening and management of postoperative complications were collected. Forty-eight studies, 3 of which provided a description of surgical techniques, were included. In relation to hand function, most authors advocated joint mobilization (n = 45) and some recommended muscle strengthening (n = 4). Static (n = 43) and dynamic splints (n = 14) and buddy taping (n = 12) were frequently recommended to prevent and manage postoperative complications. Few studies (n = 13) reported wound assessment or control of postoperative edema. Precise recommendations concerning therapeutic strategies following PIP joint arthroplasty cannot be made based on available evidence. Specific protocols for rehabilitation following PIP joint replacement need to be clarified in future research.

[Anatomy of the metacarpophalangeal and proximal interphalangeal finger joint with respect to arthroplasty]

BACKGROUND

Precise knowledge of the anatomy and biomechanics of the metacarpophalangeal and proximal interphalangeal joint is the basis for both indication and implantation of a finger joint prosthesis. Currently available finger joint prostheses inadequately take into account individual, ethnological, gender, age, and side differences. They can remain compromised despite the possible combination of their components.

OBJECTIVES

To elucidate which problems of finger joint arthroplasty exist due to the anatomy and biomechanics of the metacarpophalangeal and proximal interphalangeal joints.

METHODS

The anatomy and biomechanics of the metacarpophalangeal and proximal interphalangeal joint are described, and the problems and solutions of finger joint arthroplasty are presented.

RESULTS

Despite precise knowledge of the anatomy and biomechanics of the metacarpophalangeal and proximal interphalangeal joint, not all problems of finger joint arthroplasty have been solved. However, a modular surface replacement appears promising for the proximal interphalangeal joint.

CONCLUSIONS

Artificial joint replacement of the metacarpophalangeal and proximal interphalangeal joint is difficult with regard to morphology, small bone dimensions, complex biomechanics, and the strain of the hand. Further improvements, especially in design, should be achieved by exact anatomical imitation.

Complications, reoperations and revisions after proximal interphalangeal joint arthroplasty: a systematic review and meta-analysis

This systematic review and meta-analysis investigates the prevalence of complications, reoperations (surgeries without implant modifications) and revisions (surgeries with implant modifications) after proximal interphalangeal joint arthroplasty with pyrocarbon, metal-polyethylene and silicone implants. Thirty-four articles investigating 1868 proximal interphalangeal joints were included. Implant-related complications were associated with 14%, 10% and 11% of the pyrocarbon, metal-polyethylene and silicone implants, respectively, yet these rates were not significantly different from one another. Silicone implants showed more finger deviations (3%) and instabilities (2%) compared with the other implants. Reoperations were fewer for silicone arthroplasties (1%) compared with pyrocarbon (7%) and metal-polyethylene implants (10%). The revision rates of 4%, 3% and 2% were similar for pyrocarbon, metal-polyethylene and silicone implants. Our results indicate that silicone implants remain a valuable option for the treatment of stable proximal interphalangeal joints. Surface replacing implants might be better to correct unstable or deviated proximal interphalangeal joints, although they are associated with a higher risk of reoperations.

[Advances in small joint reconstruction and arthroplasty of the hand]

Since Swanson designed the silicone small joint prosthesis, the material and design of the small joint prosthesis have been constantly innovating. The number of small joint reconstruction and arthroplasty has gradually increased in the past decade. The numerous studies have focused on design and application of new material prosthesis and its long-term effectiveness analysis, in order to overcome prosthesis loosening, shift, dislocation, and poor function problem, at the same time to challenge the difficulty of the small joints revision procedures. Although the small joint prosthesis which has got the overall performance of the Swanson joints and been mature and stable like a knee joints prosthesis has not been obtained, but the small joint development has made revolutionary changes in the treatment of joint diseases, and the prosthesis selection criterion and surgical technique tendency solution have been established. In the future, digital three-dimensional printing, regenerative medicine, and translational medicine will contribute to the development of small joint reconstruction and replacement.

Biomechanical evaluation of pyrocarbon proximal interphalangeal joint arthroplasty: An in-vitro analysis

BACKGROUND

Pyrocarbon proximal interphalangeal joint arthroplasty provided patients with excellent pain relief and joint motion, however, overall implant complications have been very variable, with some good outcomes at short-medium-term follow-up and some bad outcomes at longer-term follow-up. Implant loosening with migration, dislocation and implant fracture were the main reported clinical complications. The aim of the present work was to test the hypothesis that the magnitude proximal interphalangeal joint cyclic loads in daily hand functions generates stress-strain behaviour which may be associated with a risk of pyrocarbon component loosening in the long-term.

METHODS

This study was performed using synthetic proximal and middle phalanges to experimentally predict the cortex strain behaviour and implant stability considering different load conditions for both intact and implanted states. Finite element models were developed to assess the structural behaviour of cancellous-bone and pyrocarbon components, these models were validated against experimentally measured cortex strains.

FINDINGS

Cortex strains showed a significant increase at dorsal side and reduction at palmar side between intact and implanted states. Cancellous-bone adjacent to the condylar implant base components suffers a two to threefold strain increase, comparing with the intact condition.

INTERPRETATION

The use of pyrocarbon implant changes the biomechanical behaviour of the joint phalanges and is associated with a potential risk of support cancellous-bone suffer fatigue failure in mid to long term due to the strain increase for cyclic loads in the range of daily hand activities, this risk is more prominent than the risk of bone resorption due to strain-shielding effect.

A Systematic Review of Different Implants and Approaches for Proximal Interphalangeal Joint Arthroplasty

BACKGROUND

Outcomes after implant arthroplasty for primary degenerative and posttraumatic osteoarthritis of the proximal interphalangeal joint were different according to the implant design and surgical approach. The purpose of this systematic review was to evaluate outcomes of various types of implant arthroplasty for proximal interphalangeal joint osteoarthritis, with an emphasis on different surgical approaches.

METHODS

The authors searched all available literature in the PubMed and EMBASE databases for articles reporting on outcomes of implant arthroplasty for proximal interphalangeal joint osteoarthritis. Data collection included active arc of motion, extension lag, and complications. The authors combined the data of various types of surface replacement arthroplasty into one group for comparison with silicone arthroplasty.

RESULTS

A total of 849 articles were screened, yielding 40 studies for final review. The mean postoperative arc of motion and the mean gain in arc of motion of silicone implant with the volar approach were 58 and 17 degrees, respectively, which was greater than surface replacement implant with the dorsal approach at 51 and 8 degrees, respectively. The mean postoperative extension lag of silicone implant with the volar approach and surface replacement with the dorsal approach was 5 and 14 degrees, respectively. The revision rate of silicone implant with the volar approach and surface replacement with the dorsal approach was 6 percent and 18 percent at a mean follow-up of 41.2 and 51 months, respectively.

CONCLUSION

Silicone implant with the volar approach showed the best arc of motion, with less extension lag and fewer complications after surgery among all the implant designs and surgical approaches.

Proximal interphalangeal (PIP) joint replacements with pyrolytic carbon implants in the hand

Until the late 1980s, proximal interphalangeal (PIP) joint reconstruction had been almost exclusively performed by the use of monobloc silicone spacers and associated with acceptable to good clinical outcomes.

More recently, new materials such as metal-on-polyethylene and pyrocarbon implants were proposed, associated with good short-term and mid-term results.

Pyrocarbon is a biologically inert and biocompatible material with a low tendency to wear. PIP pyrolytic implants are characterised by a graphite core, visible on radiographs and covered by a radiolucent outer layer of pyrocarbon.

New surgical techniques and better patient selection with tailored rehabilitative protocols, associated with the knowledge arising from the long-term experience with pyrocarbon implants, has demonstrated noteworthy clinical outcomes over the years, as demonstrated by recent studies.

Cite this article: EFORT Open Rev 2017;2:21–27. DOI: 10.1302/2058-5241.2.160041

In vitro wear testing of the PyroCarbon proximal interphalangeal joint replacement: Five million cycles of flexion and extension

Clinical results of the PyroCarbon proximal interphalangeal joint replacement are inconsistent with various complications reported. To address this, in vitro testing was conducted using finger joint simulators. Two PyroCarbon proximal interphalangeal prostheses were tested in a lubricant of dilute bovine serum to 5 × 10(6) cycles of flexion-extension (90°-30°) with dynamic forces of 10 N applied. At intervals of 3000 cycles testing ceased and a static load of 100 N was applied to simulate gripping. In addition, two 'control' prostheses were immersed alongside the test prostheses to account for lubricant absorption. Wear and roughness averages (Ra) were measured every 1 × 10(6) cycles. Minimal wear for all of the components was measured with a negligible increase in Ra for most of the components. One condyle of one component increased in Ra over the 5 × 10(6) cycles with a value above the recommended 50 nm. Unidirectional marks were visible on the condyle from micrographs, consistent with an abrasive wear mode.

Pyrocarbon proximal interphalangeal joint arthroplasty: a medium to long term follow-up of a single surgeon series

We retrospectively reviewed a consecutive single surgeon series of 57 Ascension pyrocarbon proximal interphalangeal joint arthroplasties, with a mean follow-up of 7.1 years (range 2 years to 11 years 6 months). We assessed the ranges of motion, deformity, stability and pain of the operated joints, grip strength of the hand and patient satisfaction. Of the cases, 44 were for osteoarthritis, five for rheumatoid arthritis and eight for post-traumatic arthritis. The median post-operative active arc of motion was from 0° to 60°. The median post-operative visual analogue pain score was 0.3 out of ten. Thirty six of the joints had no complications; 14 had minor complications (squeak, slight swan neck); three required early reoperation (joint release, flexor tenodesis); and five required implant removal. A total of 69% of our patients would have the same operation if they had to make the decision again. The Kaplan-Meier survival method estimates the mean implant survival to be 10.7 years (95% confidence intervals 9.96-11.37 years). All five failures occurred during the first 2 years.Level of evidence 4 (Case-series).

Pyrocarbon Proximal Interphalangeal Joint Arthroplasty: Minimum Five-Year Follow-Up

PURPOSE

To report the outcomes, complications, and survivorship of pyrocarbon proximal interphalangeal joint arthroplasty at a minimum of 5-year follow-up.

METHODS

A review of 97 implants in 72 consecutive patients from our joint arthroplasty database was undertaken. Patient demographics, complications, further surgery, and implant revision were recorded. Objective outcome was assessed by grip strength, range of motion, and radiological assessment of alignment, loosening, and subsidence. Subjective outcome was assessed by Patient Evaluation Measure; Quick Disabilities of the Arm, Shoulder, and Hand score; and visual analog scores (0, best; 10, worst) for appearance, satisfaction, and pain.

RESULTS

Diagnosis was osteoarthritis in 60 joints, rheumatoid arthritis in 12 joints, psoriatic arthritis in 11 joints, and trauma in 14 joints. The average follow-up was 118 months (range, 60-164 months). The mean arc of motion was 35° (range, 0° to 90°). There was no difference in grip strength between operated and nonoperated side. Of the 97 implants, 36 required additional surgery, of which 14 were revised and 22 required reconstruction around a retained implant. The average Patient Evaluation Measure and Quick Disabilities of the Arm, Shoulder and Hand scores were 33 (range, 10-69) and 35 (range, 0-93), respectively. Mean visual analog scores for pain, satisfaction, and appearance were 2 (range, 0-8), 7 (0-10), and 8 (0-10), respectively. All implants had a lucent line with nearly all classified as either Herren grade 2 or 3. Progressive loosening was seen in 48% of implants. Implant survival as assessed by Kaplan-Meier was 85% at both 5 and 10 years.

CONCLUSIONS

Good pain relief and maintenance of preoperative arc of motion was achieved with no major deterioration over time. Most implant revisions were performed within 24 months of the index procedure. Currently progressive loosening was not translated into revision surgery. Implant revision rate was higher than with other prostheses.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Pyrolytic carbon hemiarthroplasty in the management of proximal interphalangeal joint arthritis

PURPOSE

To review clinical, subjective, and radiographic results of pyrocarbon hemiarthroplasty for proximal interphalangeal (PIP) joint arthritis.

METHODS

A total of 42 fingers in 38 patients underwent PIP joint hemiarthroplasty between 2005 and 2011. Preoperative diagnoses included 28 with osteoarthritis or posttraumatic arthritis and 10 with inflammatory arthritis. Average age at the time of surgery was 56 years. Digits treated included: index (10), middle (20), ring (9), and little (3). Average follow-up was 4.6 years (minimum, 2 y).

RESULTS

There was considerable improvement in patient satisfaction measures including Canadian Occupational Performance Measure for both performance and satisfaction and Disabilities of the Arm, Shoulder, and Hand and visual analog scale pain scores. There was no significant change in motion or grip and pinch strength after surgery. Four joints were revised for failure: 3 underwent arthrodesis and 1 was converted to a silicone PIP joint arthroplasty. Radiographic outcomes in surviving implants demonstrated a Sweets and Stern grade 0 in 37 implants and grade 3 in 1.

CONCLUSIONS

Pyrocarbon hemiarthroplasty appears to be a viable alternative to total joint arthroplasty in the treatment of PIP joint arthritis. Clinical and patient satisfaction outcomes compared favorably with published outcomes of arthroplasty. Radiographic outcomes of PIP joint hemiarthroplasty were encouraging with respect to implant position and loosening. Compared with total joint arthroplasty, proximal hemiarthroplasty is a simple procedure that preserves more bone stock and would allow for better success of salvage options such as arthrodesis and revision arthroplasty.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Insertion of the Ascension PyroCarbon PIP total joint in 152 human cadaver fingers: analysis of implant positions and malpositions

INTRODUCTION

The Ascension PyroCarbon proximal interphalangeal (PIP) total joint is used in osteoarthritis of the PIP finger joint. No systematic study of the positioning of this prosthesis and its relation to proximal and middle phalanx morphology has yet been reported.

MATERIALS AND METHODS

Positioning of the proximal and distal components of the Ascension PyroCarbon PIP total joint was radiographically analysed in 152 human cadaver fingers.

RESULTS

Ideal implant position in the axis of the phalanx and with contact of the implant head with bone in both the frontal and sagittal planes was seen in only 33 % of the phalanges. Implant malposition was observed in the remaining 67 % of phalanges.

CONCLUSION

The current design of the Ascension PyroCarbon PIP total joint can lead to malpositioning that we attribute to its incomplete accommodation of the morphology of the proximal and middle phalanx, the surgical challenges the design poses, or both acting together.

Ten year follow-up of pyrocarbon implants for proximal interphalangeal joint replacement

Results of anatomical resurfacing of the proximal interphalangeal joint using pyrocarbon implants showed reasonable clinical results with a high radiographic migration rate. The aim was to investigate the subjective, clinical, and radiographic results 10 years following surgery, and to compare them with our 2-year follow-up data. We re-evaluated 12 patients with 15 proximal interphalangeal implants on average 9.7 years after surgery. Pain significantly improved from 7.6 on a visual analogue scale pre-operatively to 1.4 at 2 years, and to 0.7 at the final follow-up. The mean total range of motion in all replaced joints was 36° pre-operatively and 39° at the 2-year follow-up, but had decreased significantly to 29° at 10 years. We saw one implant migration in addition to the eight migrated implants we already found 2 years after surgery. The moderate clinical results, combined with the high migration rate, mean that we no longer use this kind of implant.

Ten years' experience with a pyrocarbon prosthesis replacing the proximal interphalangeal joint. A prospective clinical and radiographic follow-up

We prospectively assessed the subjective, objective, and radiographic results at 1, 2, and 5 years in 65 patients who had pyrocarbon proximal interphalangeal prostheses inserted between 2001 and 2010. Further operations were done on 10 of the 89 joints (four for prosthetic extraction and arthrodesis, two for component changes, and four for soft tissue procedures). At 1 year, the visual analogue scale score for pain at rest had improved to 0 cm from a pre-operative 4 cm, pain at activity from 6 to 1.8 cm, and Disability of the Arm, Shoulder and Hand score from 40 to 25. Range of movement and grip strength were unchanged. At 5 years, 31 joints (21 patients) had a complete radiographic follow-up. Seven proximal and 12 distal components showing zones of osteolysis at 1 year had stabilized and were inert or integrated at 5 years. Three proximal and three distal components had osteolytic zones at 5 years. Forty-seven of 59 patients were pain-free at rest at 1 year, and 19 of 21 at 5 years. No late revisions or loosening occurred.

Morphology of the proximal and middle phalanx of fingers with regard to the Ascension PyroCarbon PIP total joint

The Ascension PyroCarbon prosthesis has been used in proximal interphalangeal joint osteoarthritis. The dimensions of the intramedullary distal metadiaphyseal canal (isthmus) of the proximal phalanx and the base of the middle phalanx of cadaver fingers were investigated radiographically (n = 304) and macroscopically (n = 152). In up to 30% of the phalanges, the isthmus was smaller than the stem of the smallest proximal component size. The distal component head was always smaller than the middle phalanx base. Insertion and success of the Ascension PyroCarbon prosthesis is strongly dependent on bone morphology. A critical examination of the isthmus in radiographs is recommended in planning. If the isthmus is clearly smaller than the smallest proximal component, insertion of the prosthesis could be inadvisable. A clear mismatch between the distal component and the middle phalanx base should be avoided due to the potential risk for late subsidence and failure of the prosthesis.

OUTCOME OF PYROCARBON PROXIMAL INTERPHALENGEAL JOINT REPLACEMENT

Pyrocarbon arthroplasty of the proximal interphalangeal joint (PIPJ) has been reported to provide excellent pain relief when treating osteoarthritis of the hand. We retrospectively reviewed 20 PIPJ arthroplasties performed on 14 patients by a single surgeon using Ascension prosthesis. The mean follow up period was 3.5 years (range 1–7 years). Excellent pain relief was noted at the final follows-up. The mean range of motion improved from 40° pre-operatively to 70° post-operatively which was statistically significant. Twelve patients had significant improvement in quality of life and would consider similar procedure for other fingers. Radiological assessment revealed an average of 1 mm subsidence and there was no correlation noted between subsidence, migration and ROM at the final follow-up. Stiffness was the main complication and was comparable with other studies. The results of this series are encouraging and demonstrate excellent to good outcome in 86% of patients at the mid-term follow-up.

Proximal interphalangeal joint replacement with an unconstrained pyrocarbon prosthesis (Ascension(R)): a long-term follow-up

There have been limited publications that report long-term outcomes of pyrocarbon implants. This report describes both clinical and radiographic long-term results for patients who have been treated with pyrocarbon proximal interphalangeal implants. Thirteen implants in ten patients are reported for an average follow-up of 8.3 years (range 6.2-9.3). All patients were suffering from degenerative joint disease. Five of the 13 digits were free of pain, the remaining eight digits had mild to moderate pain (visual analogue scale 2-5). The average active range of motion was 58° (SD 19°) at latest examination. X-ray results were unremarkable in six digits with an acceptable position of the prosthesis. However, in seven patients significant radiolucent lines (≥ 1 mm) were observed. Three prostheses demonstrated a migration of the proximal component, and one a subsidence of the distal component. Our study does not support the use of this implant for treatment of osteoarthritis of the finger joint owing to high complication rates and limited range of motion.