Proximal interphalangeal joint replacement in patients with arthritis of the hand: a meta-analysis

Toward a disruptive, minimally invasive small finger joint implant concept: Cellular and molecular interactions with materials in vivo

Osteoarthritis (OA) poses significant therapeutic challenges, particularly OA that affects the hand. Currently available treatment strategies are often limited in terms of their efficacy in managing pain, regulating invasiveness, and restoring joint function. The APRICOTⓇ implant system developed by Aurora Medical Ltd (Chichester, UK) introduces a minimally invasive, bone-conserving approach for treating hand OA (https://apricot-project.eu/). By utilizing polycarbonate urethane (PCU), this implant incorporates a caterpillar track-inspired design to promote the restoration of natural movement to the joint. Surface modifications of PCU have been proposed for the biological fixation of the implant. This study investigated the biocompatibility of PCU alone or in combination with two surface modifications, namely dopamine-carboxymethylcellulose (dCMC) and calcium-phosphate (CaP) coatings. In a rat soft tissue model, native and CaP-coated PCU foils did not increase cellular migration or cytotoxicity at the implant-soft tissue interface after 3 d, showing gene expression of proinflammatory cytokines similar to that in non-implanted sham sites. However, dCMC induced an amplified initial inflammatory response that was characterized by increased chemotaxis and cytotoxicity, as well as pronounced gene activation of proinflammatory macrophages and neoangiogenesis. By 21 d, inflammation subsided in all the groups, allowing for implant encapsulation. In a rat bone model, 6 d and 28 d after release of the periosteum, all implant types were adapted to the bone surface with a surrounding fibrous capsule and no protracted inflammatory response was observed. These findings demonstrated the biocompatibility of native and CaP-coated PCU foils as components of APRICOTⓇ implants. STATEMENT OF SIGNIFICANCE: Hand osteoarthritis treatments require materials that minimize irritation of the delicate finger joints. Differing from existing treatments, the APRICOTⓇ implant leverages polycarbonate urethane (PCU) for minimally invasive joint replacement. This interdisciplinary, preclinical study investigated the biocompatibility of thin polycarbonate urethane (PCU) foils and their surface modifications with calcium-phosphate (CaP) or dopamine-carboxymethylcellulose (dCMC). Cellular and morphological analyses revealed that both native and Ca-P coated PCU elicit transient inflammation, similar to sham sites, and a thin fibrous encapsulation in soft tissues and on bone surfaces. However, dCMC surface modification amplified initial chemotaxis and cytotoxicity, with pronounced activation of proinflammatory and neoangiogenesis genes. Therefore, native and CaP-coated PCU possess sought-for biocompatible properties, crucial for patient safety and performance of APRICOTⓇ implant.

OpenHands: An Open-Source Statistical Shape Model of the Finger Bones

This paper presents statistical shape models of the four fingers of the hand, with an emphasis on anatomic analysis of the proximal and distal interphalangeal joints. A multi-body statistical shape modelling pipeline was implemented on an exemplar training dataset of computed tomography (CT) scans of 10 right hands (5F:5M, 27-37 years, free from disease or injury) imaged at 0.3 mm resolution, segmented, meshed and aligned. Model generated included pose neutralisation to remove joint angle variation during imaging. Repositioning was successful; no joint flexion variation was observed in the resulting model. The first principal component (PC) of morphological variation represented phalanx size in all fingers. Subsequent PCs showed variation in position along the palmar-dorsal axis, and bone breadth: length ratio. Finally, the models were interrogated to provide gross measures of bone lengths and joint spaces. These models have been published for open use to support wider community efforts in hand biomechanical analysis, providing bony anatomy descriptions whilst preserving the security of the underlying imaging data and privacy of the participants. The model describes a small, homogeneous population, and assumptions cannot be made about how it represents individuals outside the training dataset. However, it supplements anthropometric datasets with additional shape information, and may be useful for investigating factors such as joint morphology and design of hand-interfacing devices and products. The model has been shared as an open-source repository ( https://github.com/abel-research/OpenHands ), and we encourage the community to use and contribute to it.

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).

Proximal Interphalangeal Joint Arthroplasty Using the Wide-Awake Local Anesthesia No Tourniquet Technique

BACKGROUND

Proximal interphalangeal joint (PIPJ) osteoarthritis is a common condition that results in pain, stiffness, and loss of function in the affected hand. Proximal interphalangeal joint arthroplasty is an effective treatment option when conservative methods have failed. The wide-awake local anesthesia no tourniquet (WALANT) technique to perform surgery carries advantages such as lack of tourniquet discomfort, reduces the staffing and costs associated with anesthesia and sedation, and allows faster recovery. We aimed to determine whether the WALANT technique was safe and effective in the context of PIPJ arthroplasty.

METHODS

Patients were enrolled retrospectively from January 2015 to October 2020 by examining operating theater records and surgeon logbooks. Electronic patient records were examined to obtain patient data. Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaires and Visual Analog Scale (VAS) for pain were sent by post to patients-with a separate DASH and VAS for each digit operated on.

RESULTS

Twenty-nine PIPJ arthroplasties were carried out using WALANT technique by 3 different surgeons all using the dorsal approach. All cases were successfully carried out as day-case procedures. There was a significant correlation with increasing VAS and increasing DASH score. Proximal interphalangeal joint arthroplasty improved range of motion from 28.9 ± 5.5° to 79.4 ± 13.3° (P < .0001). Two cases developed complications related to surgery.

CONCLUSIONS

Our study is the first to report the use of WALANT to perform PIPJ arthroplasty, and shows comparable results with traditional methods. Larger, multicenter prospective trials are required to determine the efficacy of this technique and to quantify its economical benefit.

Shifting the paradigm: ankylosis arthroplasty for the proximal interphalangeal joint with a novel collateral ligament reconstruction

Silicone arthroplasty for proximal interphalangeal joint ankylosis is rarely performed, partly due to the potential for lateral joint instability. We present our experience performing proximal interphalangeal joint arthroplasty for joint ankylosis, using a novel reinforcement/reconstruction technique for the proper collateral ligament. Cases were prospectively followed-up (median 13.5 months, range 9-24) and collected data included range of motion, intraoperative collateral ligament status and postoperative clinical joint stability; a seven-item Likert scale (1-5) patient-reported outcomes questionnaire was also completed. Twenty-one ankylosed proximal interphalangeal joints were treated with silicone arthroplasty, and 42 collateral ligament reinforcements undertaken in 12 patients. There was improvement in range of motion from 0° in all joints to a mean of 73° (SD 12.3); lateral joint stability was achieved in 40 out of 42 of collateral ligaments. High median patient satisfaction scores (5/5) suggest that silicone arthroplasty with collateral ligament reinforcement/reconstruction should be considered as a treatment option in selected patients with proximal interphalangeal joint ankylosis.Level of evidence: IV.

Outcome of the MatOrtho arthroplasty for PIP osteoarthritis with a minimum follow-up of two years

The aim of this study is to report the early results of the MatOrtho arthroplasty, a newer generation resurfacing implant of the proximal interphalangeal joint. We performed a prospective cohort review of all MatOrtho arthroplasties implanted between 12/2013 and 05/2018 by a single surgeon at a single institution because of primary osteoarthritis, with a minimum follow-up of two years. Patient demographics, diagnosis, implant revision and other surgical interventions were recorded. Subjective and objective outcomes were evaluated, including range of motion, Patient Reported Outcome Measures and radiographic assessment. A total of 34 implants were inserted in 25 patients. Two implants were lost to follow-up. Pain scores improved significantly (mean VAS pre- op 7, mean VAS post-op 1, p < 0.05). Active range of motion improved in 83% (25/30) of joints, with a mean improvement of the total arc of motion of 25 degrees. On radiographic assessment, no signs of circumferential lucency or subsidence were observed. Additional surgery was necessary for three out of 32 implants, including implant removal in two cases. 93.75% (30/32) implants survived after a mean follow-up of 33 months. Our results confirm that at least at short term follow up, the MatOrtho PIP arthroplasty can be a successful procedure with high patient satisfaction and functional improvement.

Outcomes of Unconstrained Proximal Interphalangeal Joint Arthroplasty: A Systematic Review

Background: Unconstrained pyrocarbon and metal-on-polyethylene (MoP) proximal interphalangeal (PIP) joint arthroplasty is an increasingly popular alternative to silicone implants and arthrodesis. This systematic review appraises their outcomes. Methods: Thirty studies comprising 1,324 joints (813 pyrocarbon, 511 MoP) were included. Mean patient age was 59 years (38-78) and mean follow-up period was 54 months (12-118). Results: There were mean improvements of 4.5 points (2-6.9) in pain visual analogue score, 10.5° (-26 to 58) in range of motion (ROM), 3.1 kg (-4 to 7) in grip strength, 0.6 kg (-1.5 to 2) in pinch strength and 18 points (-3 to 29) in the disabilities of the arm, shoulder and hand score, with no significant differences between implant types. ROM gains deteriorated over time. Clinical complications were frequent (23%) and significantly more common with pyrocarbon, as were radiographic complications. However, most were mild-moderate and did not necessarily correlate with negative outcomes or dissatisfaction. Overall re-operation rate was 21%, and revision rate 11%, both more frequent with pyrocarbon. Most revisions were within 24 months, beyond which survival was maintained up to 10 years. Conclusions: Unconstrained PIP joint arthroplasty is effective in improving pain scores, active ROM, grip/pinch strength and patient-reported outcome measures, particularly in patients with osteoarthritis. Results are generally maintained at least to the medium term, although gains diminish in the longer term. Complication and early revision rates are high, particularly with pyrocarbon implants. Most patients express positive attitudes to arthroplasty, with significant improvements in patient-reported outcome measures for both pyrocarbon and MoP implants. Patients with post-traumatic and inflammatory arthropathy are generally less satisfied. There is currently insufficient data to recommend one implant type over another, although the early-to-medium term results of MoP implants are promising. Prospective surveillance via small joint registries is recommended. Level of Evidence: Level III (Therapeutic).

Silicone Implant Arthroplasty for Severe Bony Ankylosis of the Proximal Interphalangeal Joints in Rheumatoid Arthritis

Arthrodesis and prosthetic arthroplasty have been used to treat severe proximal interphalangeal (PIP) joint arthritis. Silicone implant arthroplasty is an established treatment for rheumatoid arthritis (RA) of the fingers. However, few studies have reported the application of silicone implant arthroplasty for the treatment of severe ankylosis of the PIP joint in RA patients. The authors report, for the first time, the case of a 46-year-old woman who presented with severe bony ankylosis of the right fourth and fifth PIP joints at greater than 90° of flexion. Proximal interphalangeal silicone arthroplasty in combination with reconstruction of the extensor mechanism was successfully performed in the affected joints. Four years after surgery, active flexion of the fourth and fifth PIP joints was 55° and 75°, respectively, with an extensor lag of only 5° without pain and joint instability. Proper repair of the extensor mechanism with shortening of the central slips and mobilization of the lateral bands dorsally was most important in maintaining the extended position of the PIP joints. Proximal interphalangeal silicone arthroplasty with intensive reconstruction of the extensor mechanism could become a potential treatment option to maintain joint mobility even in severe ankylosis of the PIP joints in RA patients. [Orthopedics. 2022;45(1):e53-e56.].

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.

Trends in Primary Proximal Interphalangeal Joint System and Revisions for Osteoarthritis of the Hand in the Medicare Database

Background: Proximal interphalangeal arthroplasty (PIPA) has been indicated for patients suffering from osteoarthritis (OA) or rheumatoid arthritis of the hand. Although there is extensive literature showing the outcomes of PIPA, there is paucity in the literature regarding trends of PIPA in patients with OA of the hand. The purpose of this study was to determine annual primary utilization and revision PIPA trends within the Medicare population with the use of an administrative database. Methods: A retrospective query was performed using the Medicare Standard Analytical Files from the PearlDiver database. Patients undergoing primary and revision PIPA with hand OA were queried using International Classification of Disease, Ninth Revision, and Current Procedural Terminology coding. Primary outcomes analyzed included annual and revision utilization of PIPA and demographic comparison of age, gender, and geographic location. Statistical analysis was primarily descriptive. An α value less than 0.05 was considered statistically significant. Results: The query returned 10 191 patients who underwent primary and revision PIPA between 2005 and 2013. Calculated annual growth rate for primary and revision PIPA was 2.40% and -0.03%, respectively (P < .001). Patients between the ages of 70 and 74 years represented most of the patients undergoing a primary PIPA, whereas patients between 65 and 69 years most commonly underwent a revision procedure. Regionally, primary and revision PIPA were most commonly performed in the South. Conclusion: The data demonstrate an increased use of primary PIPA utilization for patients with OA, whereas revision PIPA decreased. The increased use indicates the increasing demand for PIPA in the United States.

Two-component surface replacement implants compared with perichondrium transplantation for restoration of Metacarpophalangeal and proximal Interphalangeal joints: a retrospective cohort study with a mean follow-up time of 6 respectively 26 years

Background

The aim of our study was to compare the long-term outcome after perichondrium transplantation and two-component surface replacement (SR) implants to the metacarpophalangeal (MCP) and the proximal interphalangeal (PIP) joints.

Methods

We evaluated 163 joints in 124 patients, divided into 138 SR implants in 102 patients and 25 perichondrium transplantations in 22 patients. Our primary outcome was any revision surgery of the index joint.

Results

The median follow-up time was 6 years (0–21) for the SR implants and 26 years (1–37) for the perichondrium transplants. Median age at index surgery was 64 years (24–82) for SR implants and 45 years (18–61) for perichondium transplants. MCP joint survival was slightly better in the perichondrium group (86.7%; 95% confidence interval [CI]: 69.4–100.0) than in the SR implant group (75%; CI 53.8–96.1), but not statistically significantly so (p = 0.4). PIP joint survival was also slightly better in the perichondrium group (80%; CI 55–100) than in the SR implant group (74.7%; CI 66.6–82.7), but below the threshold of statistical significance (p = 0.8).

Conclusion

In conclusion, resurfacing of finger joints using transplanted perichondrium is a technique worth considering since the method has low revision rates in the medium term and compares favorable to SR implants.

Level of evidence

III (Therapeutic).

Quantifying Soft Tissue Artefacts and Imaging Variability in Motion Capture of the Fingers

This study assessed the accuracy of marker-based kinematic analysis of the fingers, considering soft tissue artefacts (STA) and marker imaging uncertainty. We collected CT images of the hand from healthy volunteers with fingers in full extension, mid- and full-flexion, including motion capture markers. Bones and markers were segmented and meshed. The bone meshes for each volunteer's scans were aligned using the proximal phalanx to study the proximal interphalangeal joint (PIP), and using the middle phalanx to study the distal interphalangeal joint (DIP). The angle changes between positions were extracted. The HAWK protocol was used to calculate PIP and DIP joint flexion angles in each position based on the marker centroids. Finally the marker locations were 'corrected' relative to the underlying bones, and the flexion angles recalculated. Static and dynamic marker imaging uncertainty was evaluated using a wand. A strong positive correlation was observed between marker- and CT-based joint angle changes with 0.980 and 0.892 regression slopes for PIP and DIP, respectively, and Root Mean Squared Errors below 4°. Notably for the PIP joint, correlation was worsened by STA correction. The 95% imaging uncertainty interval was < ± 1° for joints, and < ± 0.25 mm for segment lengths. In summary, the HAWK marker set's accuracy was characterised for finger joint flexion angle changes in a small group of healthy individuals and static poses, and was found to benefit from skin movements during flexion.

Prosthetic Arthroplasty of Proximal Interphalangeal Joints for Treatment of Osteoarthritis and Posttraumatic Arthritis: Systematic Review and Meta-Analysis Comparing the Three Ulnar Digits With the Index Finger

Background: It is common teaching that treatment of index finger alone is a relative contraindication for arthroplasty of the proximal interphalangeal joint (PIPJ). However, limited data exist reporting the digit-specific complication of PIPJ arthroplasty for the treatment of osteoarthritis or posttraumatic arthritis. The purpose of this article is to perform a systematic review and meta-analysis of the literature to assess whether the 3 ulnar digits may bear a similar instability and complication profile. Methods: Systematic searches of the MEDLINE, EMBASE, and Cochrane computerized literature databases were performed for PIPJ arthroplasty specifying by digit. We reviewed both descriptive and quantitative data to: (1) report aggregate instability and instability-related complications after non-index digit PIPJ arthroplasty; and (2) perform statistical testing to assess relative rates by digit and compared with index digits. Results: Computerized search generated 385 original articles. Five studies reporting digit-specific instability-related outcomes of silicone, pyrocarbon, or metal surface arthroplasty on 177 digits were included in the review. Meta-analysis demonstrated a 29% instability rate for long digits (n = 65), 6% for ring digits (n = 53), and 6% for small digits (n = 17), compared with 33% for index digits (n = 42). There was no difference in the overall deformity, instability, and complication rates of long versus index fingers (P = .65). Conclusions: Instability-related deformity and complication rates of long finger PIPJ arthroplasty may not be different from that of the index finger. Treatment of the long finger may be a relative contraindication to PIPJ arthroplasty. Future biomechanical and clinical studies are needed.

Surface Replacement Proximal Interphalangeal Joint Arthroplasty: A Case Series

Background: In 2012, our unit published our experience with a pyrocarbon proximal interphalangeal joint (PIPJ) implant. Due to high subsidence rates, a decision was made to change to a cemented surface replacement proximal interphalangeal joint (SR-PIPJ) implant. The purpose of this study was to assess whether the change to a cemented implant would improve the subsidence rates. Methods: Retrospective review of all patients who had a cemented SR-PIPJ arthroplasty performed from 2011 to 2013 with at least 12 months follow-up. Results: A total of 43 joints were included with an average follow-up of 26.5 months. There was a significant (P = .02) improvement in arc of motion with an average satisfaction score of 3.3 (satisfied patient). Subsidence was noted in 26% of joints with a significant difference in range of motion (P = .003) and patient satisfaction (P = .001) between the group with and without subsidence. Conclusions: The change to a cemented implant resulted in satisfied patients with an improvement in range of motion. The rate of subsidence improved but remains unacceptably high.

Proximal Interphalangeal Joint Arthroplasty in Young Patients

INTRODUCTION

This investigation compares the outcomes of proximal interphalangeal (PIP) arthroplasty in patients older than and younger than 60 years.

METHODS

Overall, 299 consecutive, primary PIP arthroplasties were performed over a 14-year period, including 126 arthroplasties performed in patients younger than 60 years. In younger patients group, a higher rate of posttraumatic and inflammatory arthritis was observed.

RESULTS

In patients younger than 60 years, 32 (25%) revision surgeries occurred. Risk of revision surgery was associated with younger age. The 10-year implant survival rate was 72% for the patients younger than 60 years versus 86% for those older than 60 years. Silicone implants decreased the risk of revision surgery, although it was increased in posttraumatic arthritis. The most common complication in young patients was dislocation (n = 21). At a mean follow-up of 6.4 years, pain levels had significantly improved in patients younger than 60 years, and PIP range of motion and pinch strength were maintained. However, older patients had improved PIP motion compared with younger patients.

CONCLUSIONS

Younger age leads higher revision rates after PIP arthroplasty, particularly in the posttraumatic setting.

LEVEL OF EVIDENCE

Therapeutic, level III.

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.

Washer and Post Augmentation of 90/90 Wiring for Proximal Interphalangeal Joint Arthrodesis: A Biomechanical Study

PURPOSE

To describe a novel construct for proximal interphalangeal (PIP) joint arthrodesis using headless cannulated screws as an intramedullary washer to augment 90/90 intraosseous wiring and compare the biomechanical properties of this construct with those of the 90/90 intraosseous wiring without headless screw augmentation.

METHODS

Biomechanical evaluation of augmented 90/90 intraosseous wiring with headless cannulated screws (group 1) or 90/90 intraosseous wiring without augmentation (group 2) for PIP joint arthrodesis was performed in 3 matched-pair cadaveric specimens (12 digits per group). Each group was loaded to 10 N in the sagittal and coronal planes and the resultant stiffness from the load-displacement curve was calculated. In extension, each group then underwent load to permanent deformation and load to catastrophic failure.

RESULTS

The augmented 90/90 intraosseous wiring with cannulated screws construct demonstrated significantly greater stiffness by 132%, 64%, 79%, and 75% in flexion, extension, ulnar, and radial displacement, respectively. During load to permanent deformation testing, a 42% greater force was required to create permanent deformation in group 1 compared than group 2. There was no significant difference between the 2 groups during load to catastrophic failure testing.

CONCLUSIONS

Augmenting 90/90 intraosseous wiring for PIP joint arthrodesis with 2 headless cannulated screws in the sagittal plane that serve as intramedullary washers for the sagittal wire and posts for the coronal wire significantly increases stiffness in all directions as well as load to permanent deformation compared with 90/90 intraosseous wiring without cannulated screw augmentation.

CLINICAL RELEVANCE

Augmentation of the 90/90 intraosseous wire construct with headless cannulated screws can be considered in patients at risk for wire cutout or implant failure.

Medium-Term Outcomes With Pyrocarbon Proximal Interphalangeal Arthroplasty: A Study of 170 Consecutive Arthroplasties

PURPOSE

The purpose of this study was to examine the medium-term outcomes of patients undergoing proximal interphalangeal (PIP) joint arthroplasty using a pyrocarbon implant.

METHODS

The study comprised an analysis of 170 PIP joint pyrocarbon arthroplasties in 99 patients with a minimum 2-year clinical follow-up. Diagnoses included inflammatory arthritis (n = 49), posttraumatic arthritis (n = 29), and osteoarthritis (n = 92). Univariate logistic regression and Kaplan-Meier survival analyses were performed.

RESULTS

At an average follow-up of 6 years (range, 2-14 years), 58 reoperations (34%) were required, including 36 (21%) involving implant revision surgery. The majority of revisions were performed for either dislocations (n = 16) or pain and stiffness (n = 14). The 5- and 10-year survival-free of revision surgery rates were 79% and 77%, respectively. The risk for revision surgery was higher in patients with posttraumatic arthritis. There were 15 intraoperative complications involving a fracture and 26 postoperative complications, including 21 dislocations. In unrevised implants, patients had significant improvements in their preoperative to postoperative pain levels, with no change in their PIP joint total arc of motion. At a mean radiographic follow-up of 5.4 years, there were 28% with grade 3+ loosening and 36% with progressive implant instability. Implant loosening or progressive instability was not associated with worse pain or PIP joint total arc of motion.

CONCLUSIONS

Approximately 1 in 5 PIP joint arthroplasties with a pyrocarbon implant will require revision surgery by 5 years, and 1 in 3 will undergo more than 1 operation. Furthermore, 1 in 4 PIP joint arthroplasties will have grade 3+ radiographic loosening and 1 in 3 will have progressive loosening or subsidence by 5 years. These results are particularly concerning in young patients and those with posttraumatic arthritis. Overall, in patients that do not require revision surgery, pain relief was improved and motion maintained.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Kinesiology taping reduces the pain of finger osteoarthritis: a pilot single-blinded two-group parallel randomized trial

Objectives

Osteoarthritis (OA) is the most common arthropathy of the hand, and current treatments carry risks of adverse events. Supportive (kinesiology) tape may be analgesic and provide functional improvement, with a low risk of adverse outcomes. We experimented with supportive tape for OA of the proximal interphalangeal joint (PIPJ) of the finger in this pilot randomized trial.

Methods

This two-group parallel randomized trial recruited adults with OA of the PIPJ of the finger. We excluded patients lacking capacity or the ability to safely apply the tape. Participants were randomized to receive kinesiology tape on the dorsum of the finger, blind to grouping. Pain was the primary outcome, which was recorded on a visual analog scale (VAS). Secondary outcomes were hand function and adverse reactions. Bootstrapped between-group analyses are reported.

Results

Ten patients were included and randomized and provided complete data. There was no significant difference in pain between the groups (mean difference of 0.4 VAS units [95% confidence interval {CI} –1.6, 0.7], p=0.4). Overall, the application of kinesiology tape reduced reported pain by 6% (mean reduction of 0.6 VAS units [95% CI 0, 1.2], p=0.04). Taping did not affect hand function or digital range of motion. There were difficulties in recruiting individuals owing to the lack of dedicated research staff.

Conclusion

Kinesiology taping may reduce the pain of OA in the finger; however, whether this is a true effect, placebo effect, Hawthorne phenomenon, or due to a statistical error (ie, type 1 error due to underpowering) is unclear. Hence, further trials are required.

Comparison of proximal interphalangeal arthroplasty outcomes with Swanson implant performed by volar versus dorsal approach

No study has compared the QuickDASH score after Swanson implant arthroplasty performed by dorsal versus volar approaches. This study compared the outcomes of PIP arthroplasties through a volar approach as described by Schneider versus a dorsal approach as described by Chamay by determining the QuickDASH score, pain and range of motion. Our series included 21 Swanson implant arthroplasty cases in 17 patients aged 62 years on average, among which 12 were females. A volar approach was performed in 9 cases (group I) and a dorsal approach was performed in 12 cases (group II). The difference between the average QuickDASH score preoperatively and at the last follow-up was strong (group I: -16.584; group II: -1.444), the difference between the average pain level preoperatively and at the last follow up was very strong (group I: -2.098; group II: -4.506), the difference in average PIP extension was not different from 0 (group: I -5.805; group II: -11.332), the difference in average PIP flexion was very strong (group I: -2.716; group II: -2.007). There were four recurrences of swan neck deformity (3 in group, 1 in group II) and one implant fracture in each group. For Swanson implant arthroplasty, the volar approach leads to better QuickDASH scores and PIP flexion compared to the dorsal approach. The volar approach did not improve PIP extension, or pain, and did not lead to dysesthesia.

X-ray Guided Steroid Injections for Proximal Interphalangeal Joint Osteoarthritis of the Fingers

BACKGROUND

Osteoarthritis of the finger proximal interphalangeal joints (PIPJ's) is common and severely limits hand function. Intra-articular steroid injections are frequently used, but there is little research assessing this treatment option.

METHODS

This was a prospective audit of patients undergoing intra-articular steroid injections into the PIPJ under image intensifier guidance. The aims were to assess the duration of pain relief, hand function and range of movement following this procedure. Fifty injected joints were followed up at six weeks, three and six months.

RESULTS

There were significant improvements in both pain scores and the range of movement for up to three months. Analgesia requirements decreased and hand function improved up to three months. By six months, patients were approaching their preinjection scores.

CONCLUSIONS

X-ray guided injections are a simple procedure which can be effectively performed in the out- patient setting, resulting in satisfied patients with improved hand function and pain scores.

Evaluating the Surface Topography of Pyrolytic Carbon Finger Prostheses through Measurement of Various Roughness Parameters

The articulating surfaces of four different sizes of unused pyrolytic carbon proximal interphalangeal prostheses (PIP) were evaluated though measuring several topographical parameters using a white light interferometer: average roughness (S_a); root mean-square roughness (S_q); skewness (S_sk); and kurtosis (S_ku). The radii of the articulating surfaces were measured using a coordinate measuring machine, and were found to be: 2.5, 3.3, 4.2 and 4.7 mm for proximal, and 4.0, 5.1, 5.6 and 6.3 mm for medial components. ANOVA was used to assess the relationship between the component radii and each roughness parameter. S_a, S_q and S_sk correlated negatively with radius (p = 0.001, 0.001, 0.023), whilst S_ku correlated positively with radius (p = 0.03). Ergo, the surfaces with the largest radii possessed the better topographical characteristics: low roughness, negative skewness, high kurtosis. Conversely, the surfaces with the smallest radii had poorer topographical characteristics.

Intraoperative Periprosthetic Fractures in Proximal Interphalangeal Joint Arthroplasty

PURPOSE

To examine the frequency, risk factors, and postoperative outcomes associated with intraoperative periprosthetic fractures during proximal interphalangeal (PIP) joint arthroplasty.

METHODS

We examined 382 consecutive PIP joint arthroplasties in 205 patients. Procedures were performed from 1998 to 2012. The patients were identified and outcomes were collected through a single institution's total joints registry, collecting additional information not contained in the prospectively collected registry through medical record examination. Multiple outcomes were analyzed relating to the fractures, the hard surgical outcomes, finger function, and radiographic findings. Statistical analysis was performed utilizing Kaplan-Meier survival models, log-rank tests, univariate analysis, Student t test and Fisher exact test.

RESULTS

Intraoperative periprosthetic fracture occurred in 5% (n = 20) of 383 PIP joint arthroplasties. All of the patients who had an intraoperative fracture were women. Lower body mass index and a diagnosis of rheumatoid arthritis were associated with a significantly higher risk of intraoperative fracture. The use of pyrocarbon implants also significantly increased fracture risk. At a median follow-up of 5.3 years, there were no refractures in the patients who sustained an intraoperative fracture. Six patients underwent revision surgery, with a 2- and 5-year survival rate free of revision surgery of 76% and 64%, respectively. These rates were not significantly different from those without intraoperative fractures. There was no significant difference in the incidence of postoperative complications between patients with or without an intraoperative fracture.

CONCLUSIONS

Intraoperative fractures occur in about 5% of PIP joint arthroplasties. These periprosthetic fractures do not appear to influence outcomes, including revision surgery, refracture rate, or other early complications. Female sex, lower body mass index, rheumatoid arthritis, and the use of pyrocarbon implants were associated with increased risk for intraoperative fractures.

CLINICAL RELEVANCE

This information may help decrease fracture risk and help surgeons identify and treat the fractures when they do occur.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

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.

Prosthetic Arthroplasty Versus Arthrodesis for Osteoarthritis and Posttraumatic Arthritis of the Index Finger Proximal Interphalangeal Joint

PURPOSE

To compare outcomes of prosthetic arthroplasty versus arthrodesis to treat index finger proximal interphalangeal (PIP) joint arthritis.

METHODS

Patients with osteoarthritis or posttraumatic arthritis of index finger PIP joints were evaluated. Digit range of motion, grip and pinch strength, patient-rated pain and satisfaction scores, Michigan Hand Questionnaire scores, and complications were recorded.

RESULTS

A total of 79 finger PIP joints were followed for a median of 67 months overall (72 months for arthroplasty and 8 months for the arthrodesis group). Sixty-five were treated with arthroplasty and 14 with arthrodesis. Patients undergoing arthroplasty experienced no significant postoperative change in PIP joint range of motion whereas all preoperative PIP joint motion was eliminated after arthrodesis. Patients undergoing arthroplasty experienced significant postoperative improvement in opposition pinch. In contrast, patients undergoing arthrodesis experienced significant improvement in both opposition and apposition pinch. There were no differences in pain relief, satisfaction, or Michigan Hand Questionnaire scores between treatment groups. Patients undergoing arthroplasty had a significantly greater mean number of complications per year and mean number of complications in the first year postoperatively. There was a 4.3 times increased risk of complication in patients undergoing arthroplasty versus arthrodesis, and Kaplan-Meier analysis revealed a shorter time to first complication among patients undergoing arthroplasty.

CONCLUSIONS

The decision for prosthetic arthroplasty versus arthrodesis in the index finger of patients with osteoarthritis or posttraumatic arthritis must be made with patient goals in mind and in light of greater risk of complications associated with arthroplasty.

Revision Proximal Interphalangeal Arthroplasty: An Outcome Analysis of 75 Consecutive Cases

PURPOSE

To examine the outcomes and complications associated with revision proximal interphalangeal (PIP) joint arthroplasty.

METHODS

An analysis of 75 consecutive revision PIP joint arthroplasties in 49 patients, performed between 1998 to 2012, was performed. The mean age at the time of surgery was 58 years. Thirty-two patients had a history of prior PIP joint trauma, and 18 patients had rheumatoid arthritis. There were 12 constrained (silicone) implants and 63 nonconstrained implants (34 pyrocarbon and 29 metal-plastic).

RESULTS

Over the 14-year period, 19 (25%) fingers underwent a second revision surgery. Second revision surgeries were performed for infection, instability, flexion contracture, and heterotopic ossification. The 2-, 5-, and 10-year survival rates were 80%, 70%, and 70%, respectively, for patients requiring a second revision for PIP joint arthroplasty. Worse outcomes were seen with postoperative dislocations, pyrocarbon implants, and when bone grafting was required. Two operations were complicated by intraoperative fractures, but neither required stabilization. Sixteen patients undergoing revision surgery experienced a postoperative complication, including 2 infections, 1 postoperative fracture, 3 cases of heterotopic ossification, and 10 PIP joint dislocations. The volar approach and the use of a pyrocarbon implant was associated with increased rates of heterotopic ossification, whereas preoperative instability increased the rates of PIP joint dislocation following revision. At a mean of 5.3 years (range, 2-10 years) follow-up, 98% of patients had good pain relief but decreased PIP joint total arc of motion.

CONCLUSIONS

Proximal interphalangeal joint arthroplasty in the revision setting represents a challenge for surgeons. Revision arthroplasty was associated with a 70% 5-year survival but with a high incidence of complications. Instability was associated with worse outcomes. In this series, silicone and metal-polyethylene implants had lower rates of implant failure and postoperative complications than ones made from pyrocarbon.

Total proximal interphalangeal joint arthroplasty for osteoarthritis versus rheumatoid arthritis--a systematic review

Osteoarthritis (OA) and rheumatoid arthritis (RA) of the proximal interphalangeal joints (PIPJ) can be treated with arthroplasty, although the complicated anatomy of the joint makes surgery challenging. Controversy exists regarding outcomes in relation to disease aetiology. This study aims to compare functional outcomes and re-operation rates in these two conditions. The electronic databases MEDLINE, EMBASE, Cochrane database and Google scholar were searched in accordance with PRISMA. The study quality was assessed using the Methodological Index for Non-Randomised Studies (MINOR). A total of 16 studies were reviewed including 506 cases in the OA and 542 in the RA group. Five studies assessed function and patient satisfaction, demonstrating a non-significant improvement in the OA group. Five studies reported re-operation rate; three showing it to be lower in the OA group and two reporting similar rates. This review suggests that those undergoing PIPJ arthroplasty for OA may have a better functional outcome and lower re-operation rate.

A Simplified Lateral Hinge Approach to the Proximal Interphalangeal Joint

Proximal interphalangeal joint replacement is an effective treatment for painful arthritis affecting the joint. However, the complication rate is relatively high, with many of these complications related to soft-tissue imbalance or instability. Volar, dorsal, and lateral approaches have all been described with varying results. We describe a new simplified lateral hinge approach that splits the collateral ligament to provide adequate exposure of the joint. Following insertion of the prosthesis the collateral ligament is simply repaired, side-to-side, which stabilizes the joint. As the central slip, opposite collateral ligament, flexor and extensor tendons have not been violated, early active mobilization without splinting is possible, and the risk of instability, swan-neck, and boutonniere deformity are reduced. The indications, contraindications, surgical technique, and rehabilitation protocol are described.

The functional range of motion of the finger joints

The purpose of this study was to measure the functional range of motion of the finger joints needed to perform activities of daily living. Using the Sollerman hand grip function test, 20 activities were assessed in ten volunteers. The active and passive range of motion was measured with a computerized electric goniometer. The position of each finger joint was evaluated in the pre-grasp and grasp positions. The functional range of motion was defined as the range required to perform 90% of the activities, utilizing the pre-grasp and grasp measurements. The functional range of motion was 19°-71°, 23°-87°, and 10°-64° at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints, respectively. This represents 48%, 59%, and 60% of the active motion of these joints, respectively. There was a significant difference in the functional range of motion between the joints of the fingers, with the ulnar digits having greater active and functional range. The functional range of motion is important for directing indications for surgery and rehabilitation, and assessing outcome of treatment.

[Proximal interphalangeal joint replacement: A comparison between the volar and dorsal approach]

INTRODUCTION

Arthropathy of the proximal interphalangeal (PIP) joint symptoms is very restrictive, and in some cases arthroplasty is required. In most of the reported series of PIP silicone arthroplasty, the technique described is the dorsal approach. As far as we know, the role of the volar approach in PIP arthroplasty has still not been adequately assessed.

OBJECTIVES

To retrospectively review the patients who had PIP joint arthroplasty, and to study the clinical and radiographic outcomes in relation to the approach: volar or dorsal.

METHODS

A total of 22 PIP joint replacements were performed between 2005 and 2010. The mean age was 56 years and the mean follow-up period was 29 months. The implant used in all patients was the Avanta® PIP Soft-Skeletal Implant (Avanta Orthopaedics, San Diego, USA). The dorsal approach was performed in 14 joints, and a volar approach in 8 joints. The preoperative clinical evaluation included a visual analogue scale (VAS) and the range of motion (ROM). The preoperative ROM mean was -15°/60° in both groups. The VAS and the ROM in the last follow-up visit were recorded and compared with preoperative values.

RESULTS

The postoperative ROM of the dorsal approach group had a mean of -15°/60°, and that of the volar approach was -2°/62°.

CONCLUSION

It was found that the volar approach in this series offers the advantages of maintaining the integrity of the extensor mechanism, resulting in a complete restoration of the extension in the range of motion.

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.

Minimally invasive midvastus versus standard parapatellar approach in total knee arthroplasty: a meta-analysis of randomized controlled trials

Objective

Minimally invasive midvastus approach (mini-midvastus) has been widely used in total knee arthroplasty (TKA). However, the clinical effects still remains controversial. This meta-analysis was based on randomized controlled trials (RCTs) aiming to quantitatively analyze the clinical efficacy of mini-midvastus versus standard parapatellar approach in TKA.

Methods

This meta-analysis was performed according to the PRISMA guidelines. A literature search for the eligible RCTs was carried out in the databases of PubMed, the Cochrane library, EMBASE and Web of Science. Two independent reviewers independently completed the study selection, data extraction, and the assessment of methodological quality. Meta-analysis was conducted by the RevMan 5.2 software.

Results

A total of 18 RCTs (937 patients with 1093 TKAs) published from 2007 to 2013 were included. The meta-analysis suggested that the mini-midvastus approach significantly improved knee range of motion (ROM) and decreased visual analog score (VAS) at postoperative 1–2 weeks (p<0.05), and there were no statistical differences in terms of knee society score (KSS) (6 weeks to 1 year), VAS (6 weeks to 6 months), ROM (6 weeks to 6 months), lateral retinacular release, blood loss, straight leg raise, hospital stay and postoperative complications between the mini-midvastus and standard parapatellar approach (p>0.05). However, the operative time was significantly longer when performing the mini-midvastus group than the parapartellar approach (p<0.05).

Conclusion

This meta-analysis found that compared with the standard parapatellar approach, the mini-midvastus approach had early advantages in the VAS and ROM, but had the disadvantage in the operative time.

Level of Evidence

Therapeutic study Level I.

Long-term results of Swanson silicone arthroplasty for proximal interphalangeal joint osteoarthritis

PURPOSE

To review the long-term outcome of the Swanson silicone arthroplasty in the osteoarthritic proximal interphalangeal (PIP) joint at a single institution.

METHODS

We identified 51 patients who had undergone PIP joint Swanson silicone arthroplasty for osteoarthritis and included in the study only those 22 patients (38 joints) who responded and could follow up. These patients returned for follow-up evaluation at an average of 10 years (range, 2-24 y). Subjective outcomes were assessed using the Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire, visual analog pain scale, and Likert questionnaire scores. Clinical and radiographic objective data were collected by measuring range of motion and coronal plane deformation and assessing final radiographs.

RESULTS

Silicone arthroplasty at the PIP joint consistently provided pain relief in patients who returned for follow-up. The average Quick-Disabilities of the Arm, Shoulder, and Hand score was 17 and the average pain visual analog scale score was 0.4. The Likert questionnaire revealed that on average, patients agreed or strongly agreed that they would have surgery again, would recommend surgery to another patient, and were satisfied at an average of 10 years after surgery. Patients had neutral responses when they rated appearance, functional improvement, and range of motion. Objectively, range of motion (flexion arc of 50°) did not significantly change from the preoperative flexion arc (55°). Radiographically, 31 implants had deformation, including 21 with implant fracture. There were 3 revisions for symptomatic implant fractures and 1 implant was removed for infection. There was no correlation between radiographs and satisfaction.

CONCLUSIONS

Despite unchanged range of motion and considerable radiographic implant deformation or fracture, patients obtained consistent pain relief and satisfaction. With an implant survivorship of 90% at average of 10 years postoperatively, silicone implant arthroplasty remains our treatment of choice for the symptomatic osteoarthritic PIP joint.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.