Avanta Versus Swanson Silicone Implants in the MCP Joint—A Prospective, Randomized Comparison of 30 Patients Followed for 2 Years

Long-Term Implant Fracture Rates Following Silicone Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis

PURPOSE

The primary objective of this study was to compare the long-term survival rates of silicone metacarpophalangeal (MCP) arthroplasties between two major implants in patients with rheumatoid arthritis, using implant fracture as an end point. We also evaluated the difference in postoperative function between patients with fractured and intact implants as a secondary objective.

METHODS

A retrospective cohort study was conducted on 372 fingers of 133 hands that underwent silicone MCP arthroplasty between January 2000 and June 2019 (mean follow-up, 7.6 years). The survival rates of Swanson-type and Sutter-type implants were compared, using implant fracture as the end point after a radiographic evaluation. Clinical measures and upper limb functional assessments using the Disabilities of the Arm, Shoulder, and Hand (DASH) score were performed in the nested cohort.

RESULTS

The 10.6-year survival rates for implant fracture of Swanson- and Sutter-type implants were 86.2% and 9.4%, respectively, with significantly higher survival noted for Swanson-type implants. The Sutter-type implant showed increased susceptibility to fracture in all four fingers compared to the Swanson-type implant. Implant fractures were primarily observed at the stem-hinge junction. There were no significant differences in upper limb function between the fractured and intact implant groups.

CONCLUSIONS

Sutter-type implants were found to be more prone to fracture compared with Swanson-type implants. However, implant fractures did not significantly affect upper limb function.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognosis IV.

Proximal Interphalangeal Joint Arthroplasty Using a Silicone Implant: A Comparison Between Integra and NeuFlex in 72 Cases

BACKGROUND

Osteoarthritis of the hand can lead to pain, stiffness, and deformation, and thus to functional disability. The purpose of this study was to compare short-term clinical outcomes of 2 silicone proximal interphalangeal (PIP) joint implants, NeuFlex and Integra, in patients with primary osteoarthritis.

METHODS

We included 72 PIP joints, of which 40 were replaced by a NeuFlex implant and 32 by an Integra implant. The average follow-up was 12 months for the Integra group and 16 months for the NeuFlex group.

RESULTS

There was no change in active flexion preoperatively and postoperatively. Extension lag and Disabilities of the Arm, Shoulder, and Hand score decreased substantially in both groups, whereas grip strength and Patient-Specific Functional Scale (PSFS) score increased. All patients were satisfied. Between groups, there was a significant difference in the PSFS score, in favor of the Integra group.

CONCLUSIONS

Both implants have excellent results, but more research is needed with more patients to prevent bias and to determine the long-term outcome of these implants.

Risk Factors Contributing to Early Implant Fracture in Silicone Metacarpophalangeal Joint Arthroplasty for Patients With Rheumatoid Arthritis

PURPOSE

To identify the risk factors associated with early implant fracture of silicone metacarpophalangeal (MCP) joint arthroplasty using the volar hinge silicone implant for patients with rheumatoid arthritis.

METHODS

We retrospectively reviewed 113 fingers of 31 hands that underwent MCP joint arthroplasty between 2008 and 2014, with a minimum follow-up of 3 years,. An implant fracture within 3 years after surgery was regarded as an early implant fracture. Patient records were reviewed for potential risk factors of age, affected fingers, ulnar drift angle, and range of motion of the MCP joint before surgery and 1 year after surgery. Candidate risk factors were compared at the level of the digit and at the patient level.

RESULTS

With fracture of the implants as the end point, Kaplan-Meier estimated survival rate was 74.3% at 3 years and 67.9% at 5 years. Early implant fracture was detected in 29 fingers. Bivariate analyses showed significant associations between early implant fracture and MCP joint arc of motion before surgery, MCP joint flexion range 1 year after surgery, and MCP joint arc of motion 1 year after surgery. Multiple logistic regression analysis showed that increased MCP joint flexion range 1 year after surgery was an independent risk factor for early implant fracture.

CONCLUSIONS

Increasing MCP joint flexion range was associated with increased fractures of the implants. We propose that the MCP joint flexion range should be restricted to less than 60° in postoperative rehabilitation; it is necessary to educate the patient to permanently avoid excessive flexion of the MCP joint.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Seven-Year Outcomes of the Silicone Arthroplasty in Rheumatoid Arthritis Prospective Cohort Study

OBJECTIVE

Rheumatoid arthritis (RA) causes destruction of the metacarpophalangeal (MCP) joints, leading to hand deformities, pain, and loss of function. This study prospectively assessed long-term functional and health-related quality-of-life outcomes in RA patients with severe deformity at the MCP joints.

METHODS

RA patients between ages 18 to 80 years with severe deformity at the MCP joints were referred to 1 of the 3 study sites. Subjects who elected to undergo silicone metacarpophalangeal joint arthroplasty (SMPA) while continuing with medical management were followed in the SMPA cohort. Subjects who elected to continue with medical management alone without surgery were followed in the non-SMPA cohort. Objective measurements included grip and pinch strength as well as arc of motion, ulnar drift, and extensor lag of the MCP joints. Patient-reported outcomes included the Michigan Hand Questionnaire (MHQ) and the Arthritis Impact Measurement Scales questionnaire. Radiographs of SMPA implants were assessed and graded as intact, deformed, or fractured.

RESULTS

MHQ scores showed large improvements post-SMPA, and baseline-adjusted expected outcomes in the SMPA group were significantly better at year 7 in function, aesthetics, satisfaction, and overall score compared to non-SMPA. SMPA subjects did not improve in grip or pinch strength, but achieved significant improvement and maintained the improvement long term in ulnar drift and extensor lag.

CONCLUSION

Benefits of the SMPA procedure are maintained over 7 years with low rates of implant fracture or deformity. Non-SMPA patients remained stable in their hand function over the 7-year study duration.

Functional and patient-reported outcomes of the Swanson metacarpo-phalangeal arthroplasty in the rheumatoid hand

INTRODUCTION

Replacement of the metacarpo-phalangeal joints (MCPJ) with silastic Swanson's implants can help decrease pain, stiffness and allow for improved function in rheumatoid arthritis (RA). There is a lack of patient reported outcome measure (PROM) studies assessing the efficacy of this procedure in RA. The aim of this study was to report any change in function, pain, stiffness and satisfaction following the Swanson MCPJ replacement using patient reported outcomes in a rheumatoid population.

METHODS

The combined results of 64 RA patients (71 hands) with 284 Swanson MCPJ arthroplasties (mean follow-up: 75.85 months) were assessed using the validated M-SACRAH questionnaire and a separate satisfaction questionnaire. Radiographic evaluation was performed to insure correct alignment of the hinged prosthesis postoperatively. No attempt was made to identify other predictors, radiologically or clinically. Data analysed in the study was interpreted in the context of the number of hands and survivorship was defined as implant fracture, loosening or revision.

RESULTS

The mean total functional outcome score improved by 46.2% and the total pain outcome improved by 60.2%. The total stiffness outcome improved by 56.9% postoperatively and the results obtained from the satisfaction questions revealed that 73.2% of patients would retrospectively elect to have the procedure again. We report two postoperative complications in this group of superficial wound infections. Radiographically, all MCPJs showed improved alignment, however five patients reported worsening pain, four patients reported increased stiffness and four reported reduced function postoperatively. There was one re-operation of a 5th MCPJ Swanson's, which did not require implant exchange and one implant was revised. Implant survivorship was 98.6%.

CONCLUSIONS

Patient satisfaction and functional surrogate markers were overall favourable. Our results support the continued use of Swanson silastic arthoplasty in advanced RA.

Is Swanson prosthesis better than Sutter prosthesis for metacarpophalangeal joint arthroplasty? A meta-analysis

The aim of this meta-analysis is to compare the outcomes of the Swanson and Sutter prostheses (previously the Avanta prosthesis) used for metacarpophalangeal joint arthroplasty, and provide a powerful and rational conclusion regarding the use of prosthesis in MCP joint surgery. The literature search was based on PubMed, Cochrane Library, MEDLINE, EMBASE, and the Chinese National Knowledge Infrastructure. Data were evaluated using a generic evaluation tool designed by the Cochrane Bone, Joint, and Muscle Trauma Group and analysed using RevMan, version 5.0. Six randomised controlled trials were contained in this review, and five of them involving 143 patients were included in the meta-analysis. The results suggested that using the Sutter prosthesis could significantly decrease the rates of recurrence of drift when compared with the Swanson prosthesis for metacarpophalangeal joint arthroplasty (OR = 2.05, 95% Confidence interval (CI) = 1.31-3.20, p = 0.002). No significant difference in the outcomes of prosthesis fracture was found in two groups (OR = 1.07, 95% CI = 0.41-2.79, p = 0.88). Due to the limited data, the outcomes of range of motion, correction of ulnar deviation, pain, grip strength, and radiographic osteolytic changes could not be included in the meta-analyses. Theoretically, recurrence of drift was more common with Swanson prosthesis when compared with the Sutter prosthesis. No significant difference in the outcomes of prosthesis fracture was observed in two groups. More high-quality studies are required in long-term follow-up.

Silicone proximal interphalangeal joint arthroplasty for primary osteoarthritis using a volar approach

PURPOSE

To evaluate the short-term clinical and radiographic outcome of a silicone proximal interphalangeal (PIP) joint implant using a volar approach in patients with primary osteoarthritis.

METHODS

We retrospectively reviewed 36 proximal PIP joints that were replaced with Avanta silicone implants in 26 patients. Inclusion criteria were diagnosis of primary osteoarthrtitis of the PIP joint and failure to respond to conservative treatment. Clinical asessment included range of motion, patient satisfaction, and pain scores. The Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire was administered at final follow-up. Radiographs were reviewed for alignment and implant fracture. Complications were also recorded.

RESULTS

After an average follow-up of 18 months (range, 12-60 mo), pain relief was markedly reduced in all patients, decreasing from a mean score of 7.2 preoperatively to 0.4 postoperatively. The arc of active motion of the PIP joint improved from 33° to 72°. Satisfaction averaged 4.8 on a 5-point Likert scale, and all patients stated they would repeat the surgery. The median final average Quick-Disabilities of the Arm, Shoulder, and Hand score was 7 (range, 4-12). Radiograph review showed 2 implant fractures at 1 and 2 years after surgery, respectively, but without clinical changes. The average deformity in the coronal plane changed from 12° (range, 8° to 18°) preoperatively to 4° (range, 3° to 8°) postoperatively, whereas the average flexion contracture changed from 18° (range, 10° to 30°) to 0° (all patients achieved full active extension). No other complications were observed. No revision surgery has been needed to date.

CONCLUSIONS

The volar approach to PIP joint silicone arthroplasty offers the advantages of maintaining the integrity of the extensor mechanism, providing pain relief, and improving postoperative range of motion with minimal complications. However, further research is needed to determine the long-term efficacy of this implant.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The rheumatoid metacarpophalangeal joint

Rheumatoid metacarpophalangeal joint deformities remain an important cause of disability. Surgical intervention in carefully selected patients improves function and prolongs independence. This article discusses the commonly used reconstructive techniques and their benefits. Case selection through a combined clinic with rheumatologists and hand therapists is recommended.

Bioreconstructive poly-L/D-lactide implant compared with Swanson prosthesis in metacarpophalangeal joint arthroplasty in rheumatoid patients: a randomized clinical trial

It was hypothesized that the bioresorbable interposition implant might offer a viable alternative to conventional silicone implant arthroplasty in rheumatoid metacarpophalangeal joint destruction. A randomized clinical study was performed to compare a stemless poly-L/D-lactide copolymer 96 : 4 (PLDLA) implant with the Swanson silicone implant. Results in 52 patients (53 hands and 175 joints) at a mean follow-up of 2 years (minimum 1 year) showed that the improvement in clinical assessments was comparable in both groups, except for better maintenance of palmar alignment in the Swanson group. The lack of implant fractures and intramedullary osteolysis were advantages of the PLDLA implant. The bioresorbable PLDLA interposition implant may offer an alternative tool for tailored reconstruction of rheumatoid metacarpophalangeal joints.

The effect of radioscapholunate fusion on wrist movement and the subsequent effects of distal scaphoidectomy and triquetrectomy

Radioscapholunate arthrodesis is a salvage procedure indicated for osteoarthritis of the radiocarpal joint involving the lunate facet of the radius. This cadaver study examines changes in wrist motion resulting from radioscapholunate arthrodesis, and the effects of surgical techniques to improve the range of motion. Simulated radioscapholunate arthrodesis, distal scaphoidectomy and triquetrectomy were carried out sequentially on six cadaver forearms and measurements (maximum flexion/extension and radial/ulnar deviation) were taken in the intact situation and after each surgical step using a magnetic tracking device. Radioscapholunate arthrodesis diminishes the amplitudes of movements of the wrist in all directions, but range of motion in the radioscapholunate fused wrist improves after scaphoidectomy and improves further after triquetrectomy (88% of original flexion/extension and 98% of original radial/ulnar deviation). Radioscapholunate arthrodesis causes a significant change in kinematics between the hamate and the triquetrum in flexion/extension.

NeuFlex and Swanson metacarpophalangeal implants for rheumatoid arthritis: prospective randomized, controlled clinical trial

PURPOSE

To compare postoperative range of motion (ROM) and function in a randomized prospective trial of Swanson and NeuFlex metacarpophalangeal (MCP) joint implants.

METHODS

A total of 33 patients who had rheumatoid arthritis underwent primary MCP arthroplasty of all 4 fingers in 40 hands; 20 received Swanson implants and 20 received NeuFlex implants. Exclusion criteria included diagnosis of other connective tissue disorders and previous MCP joint surgery. All participants followed the same postoperative rehabilitation protocol. The primary outcome measure was active MCP flexion. Secondary outcomes included active MCP extension, arc of motion, ulnar drift, function (Jamar grip strength and Sollerman hand function test), and the Michigan Hand Questionnaire. Patients were assessed preoperatively and 12 months postoperatively.

RESULTS

Patients' mean age was 62.5 years (Swanson) and 58.1 years (NeuFlex) (p = .03). A total of 19 of 20 hands (Swanson) and 14 of 20 hands (NeuFlex) were from female patients. Preoperative active ROM was not significantly different. At follow-up, both groups demonstrated increased active extension and arc of motion (p < .001), reduced active flexion and improved ulnar deviation (p < .001), increased mean Sollerman and Michigan Hand Questionnaire domain scores (p < .001), and improved grip strength (p = .03). Active MCP flexion was significantly greater in all 4 digits of hands with NeuFlex implants compared with Swanson implants. The NeuFlex group demonstrated a greater total arc of motion in the little finger. Implant groups were not significantly different by individual digit for active MCP extension, ulnar drift, and composite flexion. Functional outcomes did not differ between groups. Patients with Swanson implants reported higher Michigan Hand Questionnaire scores in the function and aesthetics domains.

CONCLUSIONS

Both implant groups obtained satisfactory clinical improvement after MCP reconstruction of the hand. The NeuFlex group demonstrated superior ROM, whereas the Swanson group had better self-reported function and aesthetics, but not objectively measured function.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Correlation between range of motion and implant fracture: a 5 year follow-up of 72 joints in 18 patients in a randomized study comparing Swanson and Avanta/Sutter MCP silicone prosthesis

Eighteen out of 18 rheumatoid patients (at one centre of a two-centre 30 patient study previously reported) with a mean age of 56 years, and 72/72 operated joints were randomized to Avanta/Sutter or Swanson MCP prostheses and followed for 5 years. Both ulnar deviation and extension lag were improved already at 6 weeks and remained improved at 5 years. The Avanta prosthesis had a better range of motion (ROM) than the Swanson. Six of nine patients with Avanta/Sutter implants had at least one implant fracture compared to 1/9 patients with the Swanson implant (P = 0.05) but fracture did not change the outcome subjectively. The ROM at 3 months correlated with the occurrence of an implant fracture at 5 years and a greater early ROM may be related to implant fracture. At 5 years patients remained satisfied and the deformities remained corrected.

NeuFlex compared with Sutter prostheses: A blind, prospective, randomised comparison of Silastic metacarpophalangeal joint prostheses

Forty patients (156 metacarpophalangeal joints) with mutilating rheumatoid arthritis were randomly allocated in a blinded manner to have either NeuFlex or Sutter implants. Indications for operation were pain and severe deformity. Thirty-nine patients were followed up postoperatively for one year. An independent physiotherapist and occupational therapist examined each one. Grip strength, range of motion, and pain during activity and at rest were measured. The Canadian Occupational Performance Measure (COPM) assessed the patients' evaluation of their occupational performance. Both groups had overall good results, but it seems that though patients' mobility and grip strength improve considerably, pain seems to do so only relatively. Most patients seem to be satisfied with the operation and their functional gain. Five out of 78 Sutter and two out of 78 NeuFlex implants broke. We found no major differences between the two designs, but the patients in the NeuFlex group seemed to be more satisfied with their occupational performance (COPM performance) (p=0.05).

Osteolysis after Sutter metacarpophalangeal arthroplasty: A prospective study of 282 implants followed up for 5.7 years

Our aim was to evaluate the incidence and degree of osteolysis in a prospective series of patients with rheumatoid arthritis operated on with Sutter implants. Eighty-seven of the 110 operated hands (104 patients) with 282 implants were evaluated after a mean of 5.7 years (2.1-7.4). Osteolytic changes were present in 142 (50%) of the metacarpal and 152 (54%) of the phalangeal bones. Twenty-six of the metacarpal (9%) and 36 of the proximal phalangeal (13%) bones had osteolytic changes that did not affect the cortical bone. Cortical invasion was recorded in 100 (35%) of the metacarpal and 103 (37%) of the proximal phalangeal bones. The cortex was perforated in both bones in 14 (5%). Osteolytic changes were related to fractures of implants and to the dominant hand, but not to pain. Surgeons who operate on patients with rheumatoid diseases should note that silicone rubber implants often cause osteolytic changes.

Intra- and inter-rater reliability of the Sollerman hand function test in patients with chronic stroke

PURPOSE

To examine whether the Sollerman hand function test is reliable in a test-retest situation in patients with chronic stroke.

METHOD

Three independent examiners observed each patient at three experimental sessions; two days in week 1 (short-term test-retest) and one day in week 4 (long-term test-retest). A total of 24 patients with chronic stroke (mean age; 59.7 years, mean time since stroke onset 29.6 months) participated. The examiners simultaneously assessed the patients' ability to perform 20 subtests. Both ordinal data (generalized kappa) and total sum scores (Spearman's rank correlation coefficient (Spearman's rho), intra class correlation coefficient (ICC2, 1) and mean differences) were used in the statistical analysis.

RESULTS

There was agreement (kappa >or= 0.4) between the examiners for 15 out of the 20 subtests. Using total sum scores, the agreement within the examiners, both short- and long-term, was higher than 0.96 (for Spearman's rho and ICC, respectively). The mean differences were 0.29 - 1.0/80 points within each examiner. Agreement between the examiners at each session was higher than 0.96 (Spearman's rho) and 0.92 (ICC), respectively. Systematic differences (p < 0.05) were, however, found between examiners A and B/C for all sessions.

CONCLUSIONS

The Sollerman hand function test seems to be a reliable test in patients with chronic stroke, but we recommend that the same examiner evaluates a patient's hand function pre- and post-treatment.

Measures and time points relevant for post-surgical follow-up in patients with inflammatory arthritis: a pilot study

Background

Rheumatic diseases commonly affect joints and other structures in the hand. Surgery is a traditional way to treat hand problems in inflammatory rheumatic diseases with the purposes of pain relief, restore function and prevent progression. There are numerous measures to choose from, and a combination of outcome measures is recommended. This study evaluated if instruments commonly used in rheumatologic clinical practice are suitable to measure outcome of hand surgery and to identify time points relevant for follow-up.

Methods

Thirty-one patients (median age 56 years, median disease duration 15 years) with inflammatory rheumatic disease and need for post-surgical occupational therapy intervention formed this pilot study group.

Hand function was assessed regarding grip strength (Grippit), pain (VAS), range of motion (ROM) (Signals of Functional Impairment (SOFI)) and grip ability (Grip Ability Test (GAT)). Activities of daily life (ADL) were assessed by means of Disabilities of the Arm, Shoulder and Hand Outcome (DASH) and Canadian Occupational Performance Measure (COPM). The instruments were evaluated by responsiveness and feasibility; follow-up points were 0, 3, 6 and 12 months.

Results

All instruments showed significant change at one or more follow-up points. Satisfaction with activities (COPM) showed the best responsiveness (SMR>0.8), while ROM measured with SOFI had low responsiveness at most follow-up time points. The responsiveness of the instruments was stable between 6 and 12 month follow-up which imply that 6 month is an appropriate time for evaluating short-term effect of hand surgery in rheumatic diseases.

Conclusion

We suggest a core set of instruments measuring pain, grip strength, grip ability, perceived symptoms and self-defined daily activities. This study has shown that VAS pain, the Grippit instrument, GAT, DASH symptom scale and COPM are suitable outcome instruments for hand surgery, while SOFI may be a more insensitive test. However, the feasibility of this protocol in clinical practice awaits prospective studies.

Analysis of the mechanism of fracture of silicone metacarpophalangeal prostheses

Eleven fractured Sutter metacarpophalangeal prostheses were obtained from the hands of three patients. All of the implants had fractured at the junction of the distal stem and the hinge. After visual examination, the fracture faces were prepared and viewed using a scanning electron microscope. These images indicated that fracture was initiated by abrasion on the dorsal aspect of the distal stem of the prostheses, close to the hinge. Crack propagation was shown to be due to a fatigue process. Once a crack started, its direction of travel could be followed, using topographical features common to engineering fracture analyses. Propagation was from radial to ulnar and from dorsal to palmar.

Knowledge translation: putting the "practice" in evidence-based practice

Knowledge translation (KT) is an iterative process that involves knowledge development, synthesis, contextualization, and adaptation, with the expressed purpose of moving the best evidence into practice that results in better health processes and outcomes for patients. Optimization of the process requires engaged interaction between knowledge developers and knowledge users. Knowledge users include consumers, clinicians, and policy makers. KT is highly reliant on understanding when research evidence needs to be moved into practice. Social, personal, policy, and system factors contribute to how and when change in practice can be accomplished. Evidence-based practitioners need to understand a conceptual basis for KT and the evidence indicating which specific KT strategies might help them move best evidence into action in practice. Audit and feedback, knowledge brokering, clinical practice guidelines, professional standards, and "active-learning" continuing education are examples of KT strategies.

Crack growth of medical-grade silicone using pure shear tests

Silicone elastomers are commonly used in the manufacture of single-piece joint replacement implants for the finger joints. However, the survivorship of these implants can be poor, with failure typically occurring from fracture of the stems. The aim of this paper was to investigate the crack growth of medical-grade silicone using pure shear tests. Two medical-grade silicones (C6-180 and Med82-5010-80) were tested. Each sample had a 20 mm crack introduced and was subjected to a sinusoidally varying tensile strain, with a minimum of 0 per cent and a maximum in the range 10 to 77 per cent. Testing was undertaken at a frequency of 10 Hz. At various times during testing, the testing machine was stopped, the number of cycles completed was noted, and the crack length measured. Graphs of crack length against number of cycles were plotted, as well as the crack growth rate against tearing energy. The results show that Med82-5010-80 is more crack resistant than C6-180. Graphs of crack growth rate against tearing energy can be used to predict the failure of these medical-grade elastomers.

Insufficient flexion of the metacarpophalangeal joint of the little finger following Swanson silicone arthroplasty for rheumatoid arthritis

Twenty-one patients with rheumatoid arthritis who underwent Swanson metacarpophalangeal (MP) arthroplasty from 1994 to 1999 were assessed for active flexion of individual MP joints an average of 59 months (range 27-114 months) postoperative. Published articles of Swanson MP arthroplasty were reviewed. Experienced hand surgeons were surveyed regarding outcomes of metacarpophalangeal arthroplasty. The MP joint of the little finger displayed significantly less flexion than that of the middle and index finger. Seven of eight published studies which present active MP flexion by individual digit demonstrated less flexion in the little finger compared to the index, middle, and ring finger. Half of surgeons surveyed reported that MP range of motion is shifted toward a more extended position, that MP flexion is limited in the ulnar digits, and that an implant that encourages MP flexion would be helpful. Our experience with this cohort, a review of published literature, and a survey of international experts suggest that Swanson arthroplasty frequently results in a range of flexion of the MP joint of the little finger that may be insufficient for its principal functions.

[Prosthetics of metacarpophalangeal joints]

Only a few of the large number of implants developed during the last decades for replacement of the metacarpophalangeal (MCP) joint have proven to be reliable. The rates of loosening and mechanical failure of almost all types of constrained prostheses are so high that their use cannot be recommended at present. For more than 40 years silicone arthroplasty according to Swanson has been regarded as the gold standard in the prosthetic replacement of the MCP joint. In long-term studies this device provided good pain relief and a lasting correction of preoperative ulnar deviation. The degree of patient satisfaction continues to be high after more than 10 years. With the NeuFlex spacer, a modification of the original Swanson implant, a better range of motion and a reduction of wear-related problems is expected. In this study the results of 130 NeuFlex spacers after a mean time of 3.6 years were examined and 82% of the patients were completely pain free. The mobility of the joints improved from 40 degrees preoperatively to 54 degrees after 3.6 years. Radiologically periprosthetic erosions or osteolyses were seen in approximately 15% of implants. A minimal sinking of the stems developed in 24%, a massive one in 6% and 13% of the spacers were broken. Thus the use of the NeuFlex implant resulted in a better range of motion compared to the Swanson spacer, but the problem of radiological appearance remained unchanged. For unlinked prostheses sufficient soft tissue stability is mandatory as well as wear-resistant surface materials. The pyrocarbon prosthesis according to Beckenbaugh is the only implant for which long-term results are available. In a prospective study we evaluated 28 Ascension pyrocarbon prostheses with a mean follow-up of 4 years. Stability was not found to be a problem. Subjective results were satisfactory, the range of motion remained unchanged, however 46% of prosthesis stems exhibited radiolucent seams, 7 prostheses (25%) were rated as loose and 5 of those had to be replaced by a silicone implant. Use of the implant was abandoned, as it was unreliable regarding bony fixation. There are promising concepts in some new prostheses but independent data are still lacking.

Implantate der Hand

Increasingly, implants in the region of hand joints and the wrist represent an alternative for the treatment of post-traumatic, inflamed, or degenerative joint damage. The diversity of hand functions also results in varied solutions, which are effective in their stability, mobility, and distraction. Different materials are necessary for this, and they require subtile radiological control. The native X-ray represents the substantial method to observe migration of the implants. Each interface between titanium, ceramic, zirconium, pyrocarbon, and silicon to the bone has to be assessed differently in order to obtain a relevant statement. The finger joints and to a limited extent the wrist represent the artificial joints with limited alternative therapy. Other implants in the hand should only be applied after strict indication and patient compliance, as arthrodesis and resection arthroplasty have shown very good long-term results.

Rheumatoid arthritis: silicone metacarpophalangeal joint arthroplasty indications, technique, and outcomes

Silicone implant arthroplasty has been used for more than 40 years for severe rheumatoid disease at the metacarpophalangeal (MCP) joint. Multiple investigations have shown that silicone arthroplasty places the MCP joint in a more extended posture, with some improvement in the total arc of motion. Ulnar drift is also improved, but strength and other objective measures have not demonstrated marked changes postoperatively. The lack of prospective data and more complete outcome assessment has been, at least in part, responsible for the marked difference in opinions between rheumatologists and hand surgeons on the effectiveness of MCP arthroplasty. Recent reports using patient-centered outcome measures have shown that early outcome is favorable, with improvements in appearance, pain, and function.