Evidence-Based Indications for Mobile-Bearing Unicompartmental Knee Arthroplasty in a Consecutive Cohort of Thousand Knees

BACKGROUND

The indications for unicompartmental knee arthroplasty remain controversial. Previously recommended contraindications include the following: age under 60 years, weight 180 lb (82 kg) or over, patients undertaking heavy labor, chondrocalcinosis, and exposed bone in the patellofemoral joint. This study explores whether these contraindications are valid in mobile-bearing unicompartmental knee arthroplasty.

METHODS

Using a prospective series of 1000 consecutive medial unicompartmental knee arthroplasties in which the reported contraindications were not applied, the functional outcome and survival in patients with or without contraindications were compared.

RESULTS

Of the 1000 consecutive unicompartmental knee arthroplasties (818 patients), 68% (678 knees) would be considered contraindicated based on published contraindications. At a mean follow-up of 10 years (5-17), there was no difference in American Knee Society (AKS) Objective Scores (P = .05) or Oxford Knee Score (P = .08) between groups. However, knees with contraindications had significantly (P = .02) fewer poor outcomes and significantly better AKS Functional Scores (P < .001) and Tegner Activity Scores (P < .001). At 15 years, no difference in implant survival (P = .33) was observed. The 3% of unicompartmental knee arthroplasties performed in young men (age <60) weighing 180 lb or over with high activity levels, who have been reported to have poor outcomes after fixed-bearing unicompartmental knee arthroplasty, had significantly better AKS Functional Scores (P < .001), Oxford Knee Score (P = .01), and Tegner Activity Score (P < .001) at 10 years. No difference in AKS Objective Scores (P = .54) at 10 years or implant survival at 15 years (P = .75) was seen.

CONCLUSION

This large case series provides evidence that patients with the previously reported contraindications do as well as, or even better than, those without contraindications. Therefore these contraindications should not apply to mobile-bearing unicompartmental knee arthroplasty.

Heberden Oration, 1974. Human arthritis applied to animal models. Towards a better therapy

Images

Submicroscopic crystals in osteoarthritic synovial fluids

OBJECTIVES

To investigate the hypothesis that synovial fluid (SF) from patients with osteoarthritis (OA) may contain calcium phosphate crystals that are either too small, or too few in number to be identified by conventional light microscopy techniques.

METHODS

Twelve SF from 11 patients with established knee OA, five SF from patients with rheumatoid arthritis (RA), and two control samples of SF from patients with pseudogout were subjected to an enzyme/hypochlorite extraction procedure. The patients with OA and RA had no radiographic evidence of chondrocalcinosis, or SF crystals on polarised light microscopy. Extracted material was examined and analysed by analytical electron microscopy (AEM) and x ray powder diffraction (XRD).

RESULTS

Mineral was found in 11 of 12 OA samples, ranging from 2-120 micrograms/ml SF. Analytical electron microscopy revealed calcium pyrophosphate dihydrate (CPPD) crystals in five (confirmed by XRD in three) and basic calcium phosphates (BCP) in eight (five on XRD). Two samples with confirmed CPPD contained some rods with a mean length below 100 nm. The majority of BCP clusters were also less than 100 nm in diameter. BCP was detected in 1/5 RA samples. Control samples contained CPPD crystals of the expected size range of 0.42-17.9 microns.

CONCLUSIONS

The data indicate that many OA SF may contain CPPD or BCP crystals which are too small or too few in number to be identified by conventional techniques. Crystal deposition is not an 'on-off' phenomenon in OA.

Rheumatic manifestations of primary hyperparathyroidism and parathyroid hormone therapy

A frequent manifestation of severe primary hyperparathyroidism was the bone disease osteitis fibrosa cystica. Rarely, excess parathyroid hormone (PTH) was associated with gout and calcium pyrophosphate crystal deposition disease. Surgical cure of primary hyperparathyroidism was occasionally associated with pseudogout. Today, primary hyperparathyroidism is generally asymptomatic. Clinically overt rheumatologic and skeletal effects are mainly of historical interest. Skeletal disease is still detectable by more sensitive techniques. In certain circumstances, PTH may be protective and anabolic for the skeleton.

Phosphocitrate blocks nitric oxide-induced calcification of cartilage and chondrocyte-derived apoptotic bodies

OBJECTIVE

To examine whether phosphocitrate (PC) will block nitric oxide-induced calcification of cartilage or chondrocyte-derived apoptotic bodies.

DESIGN

Articular cartilage vesicles (ACV) or apoptotic bodies (AB) were isolated from untreated or 1mM sodium nitroprusside (SNP) treated porcine cartilage slices. Mineralization of ACV, AB, control untreated and SNP-treated cartilage were done in the presence or absence of PC (1mM)+/-ATP (1mM).

RESULTS

PC [1mM] blocked both the ATP-dependent and -independent mineralization in ACV and AB, untreated and SNP treated cartilage. Moreover, PC had no effect on NTPPPH activity in either ACV or AB fraction in the presence or absence of ATP suggesting that PC did not block the mineralization through the inhibition of NTPPPH activity.

CONCLUSIONS

PC inhibits nitric oxide-induced calcification of cartilage and cartilage-derived apoptotic bodies.

Outcome domains reported in calcium pyrophosphate deposition studies: A scoping review by the OMERACT CPPD working group

INTRODUCTION

Although calcium pyrophosphate deposition (CPPD) is common, there are no validated outcome domains and/or measurements for CPPD studies. The aim of this work was to identify domains that have been reported in prior clinical studies in CPPD, to inform the development of a core set of domains for CPPD studies.

METHODS

We performed a scoping literature review for clinical studies in CPPD, searching in Medline (via PubMed), EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases; published from January 1, 1946 to January 7, 2020. All reported outcomes and study design data were extracted and mapped to the core areas and domains as defined by the OMERACT Filter 2.1.The protocol was registered on PROSPERO (CRD: 42019137075; 09-07-2019).

FINDINGS

There were 112 papers identified, comprising of 109 observational studies and three randomized controlled trials. Most studies reported clinical presentations of OA with CPPD or acute CPP crystal arthritis. Outcomes that mapped to 22 domains were identified; the most frequently reported measures mapped to the following domains/sub-domains: imaging (joint damage on imaging tests - 59 studies; joint calcification on imaging tests - 28 studies), joint pain (26 studies), response to treatment (23 studies), side effects of treatment (15 studies), inflammation in the joint fluid or blood (ESR or C-reactive protein - 12 studies; synovial fluid markers - 4 studies; other blood markers - 2 studies), overall function (14 studies), joint swelling (12 studies) and range of joint movement (10 studies). Very few studies mapped to domains related to life impact, societal/resource use or longevity.

CONCLUSION

There is substantial variability in outcomes reported in CPPD studies. Outcomes that map to imaging manifestations, joint pain and response to treatment domains are most often reported.

New Proteins Contributing to Immune Cell Infiltration and Pannus Formation of Synovial Membrane from Arthritis Diseases

An inflamed synovial membrane plays a major role in joint destruction and is characterized by immune cells infiltration and fibroblast proliferation. This proteomic study considers the inflammatory process at the molecular level by analyzing synovial biopsies presenting a histological inflammatory continuum throughout different arthritis joint diseases. Knee synovial biopsies were obtained from osteoarthritis (OA; n = 9), chronic pyrophosphate arthropathy (CPPA; n = 7) or rheumatoid arthritis (RA; n = 8) patients. The histological inflammatory score was determined using a semi-quantitative scale based on synovial hyperplasia, lymphocytes, plasmocytes, neutrophils and macrophages infiltration. Proteomic analysis was performed by liquid chromatography-mass spectrometry (LC-MS/MS). Differentially expressed proteins were confirmed by immunohistochemistry. Out of the 1871 proteins identified and quantified by LC-MS/MS, 10 proteins (LAP3, MANF, LCP1, CTSZ, PTPRC, DNAJB11, EML4, SCARA5, EIF3K, C1orf123) were differentially expressed in the synovial membrane of at least one of the three disease groups (RA, OA and CPPA). Significant increased expression of the seven first proteins was detected in RA and correlated to the histological inflammatory score. Proteomics is therefore a powerful tool that provides a molecular pattern to the classical histology usually applied for synovitis characterization. Except for LCP1, CTSZ and PTPRC, all proteins have never been described in human synovitis.

Towards development of core domain sets for short term and long term studies of calcium pyrophosphate crystal deposition (CPPD) disease: A framework paper by the OMERACT CPPD working group

INTRODUCTION

Although calcium pyrophosphate deposition (CPPD) is common, there are no published outcome domains or validated measurement instruments for CPPD studies. In this paper, we describe the framework for development of the Outcome Measures in Rheumatology (OMERACT) CPPD Core Domain Sets.

METHODS

The OMERACT CPPD working group performed a scoping literature review and qualitative interview study. Generated outcomes were presented at the 2020 OMERACT CPPD virtual Special Interest Group (SIG) meeting with discussion focused on whether different core domain sets should be developed for different calcium pyrophosphate deposition (CPPD) clinical presentations and how the future CPPD Core Domain Set may overlap with already established osteoarthritis (OA) domains. These discussions informed development of a future work plan for development of the OMERACT CPPD Core Domain Sets.

FINDINGS

Domains identified from a scoping review of 112 studies and a qualitative interview study of 36 people (28 patients with CPPD, 7 health care professionals, one stakeholder) were mapped to core areas of OMERACT Filter 2.1. The majority of SIG participants agreed there was need to develop separate core domain sets for "short term" and "long term" studies of CPPD. Although CPPD + OA is common and core domain sets for OA have been established, participants agreed that existing OA core domain sets should not influence the development of OMERACT core domain sets for CPPD. Prioritization exercises (using Delphi methodology) will consider 40 potential domains for short term studies of CPPD and 47 potential domains for long term studies of CPPD.

CONCLUSION

Separate OMERACT CPPD Core Domain Sets will be developed for "short term" studies for an individual flare of acute CPP crystal arthritis and for "long term" studies that may include participants with any clinical presentation of CPPD (acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and/or CPPD + OA).

Pediatric idiopathic intervertebral disc calcification (IIDC): a challenging case

Idiopathic intervertebral disc calcification is a rare condition in children with a very good prognosis. As there are no biological markers, imaging is invaluable for diagnosing this "do not touch" lesion. While the characteristic feature is nucleus pulposus calcification at one or more cervical or thoracic levels, it is important that practitioners be able to recognize atypical patterns so that biopsy can be avoided. Here we report a case of pediatric idiopathic intervertebral disc calcification with contiguous vertebral involvement and anterior longitudinal ligament ossification.

Middle Ear Tophi: A Case Series of Two Unusual Lesions and a Report of Facial Weakness and Review of the Literature

OBJECTIVE

Tophaceous lesions of the middle ear from calcium pyrophosphate deposition disease (CPPD, or pseudogout) and gout are infrequently reported. Recognizing its characteristic findings will allow clinicians to accurately narrow the differential diagnosis of bony-appearing middle ear lesions and improve management.

PATIENTS

Two consecutive cases of tophaceous middle ear lesions presenting to a tertiary care center between January 2021 and December 2021. Neither with previous rheumatologic history.

INTERVENTIONS

Surgical excision of tophaceous middle ear lesions.

MAIN OUTCOME MEASURE

Improvements in facial weakness and conductive hearing loss.

RESULTS

The first case was a 66-year-old gentleman with progressive conductive loss, ipsilateral progressive facial weakness over years, and an opaque, irregular-appearing tympanic membrane anterior to the malleus found to have CPPD on surgical pathology, with immediate postoperative improvement of facial function. The second was a 75-year-old gentleman with progressive conductive loss and similar appearing tympanic membrane as case 1, previously diagnosed with tympanosclerosis, found to have gout on surgical pathology. In both cases, the CT showed a heterogenous, bony-appearing lesion in the middle ear, and both tophaceous lesions were a of gritty, chalky consistency intraoperatively.

CONCLUSION

Tophaceous lesions of the middle ear are rare but have similar findings. Notably, the tympanic membrane can appear opaque and irregular, and the CT demonstrates a radiopaque, heterogeneous appearance. Facial weakness is an unusual finding. Specimens of suspected tophi must be sent to pathology without formalin for accurate diagnosis.