MR imaging of intra- and periarticular soft tissues and subchondral bone in knee osteoarthritis

Clinical aspects and outcomes in osteoarthritis

Osteoarthritis (OA) is the most prevalent type of arthritis worldwide, and its incidence significantly increases with age. It commonly affects the knees, hips, spine, big toes, and hands. OA can be identified through clinical examination, symptoms, and imaging methods. Its main symptoms include pain, stiffness, and limitations in joint movement. Examinations may reveal coarse crepitus, bony enlargement, and tenderness at the joint line. In severe cases of OA, rest pain, night pain, and deformity may occur. OA can lead to decreased physical activity, function, and quality of life due to symptoms such as pain and stiffness. To evaluate these impacts, patient-reported outcome measures (PROMs) are necessary. Various generic, disease-specific, and joint-specific PROMs have been developed and used in clinical practice to assess the outcomes of OA.

Characterisation of first metatarsophalangeal joint osteoarthritis using magnetic resonance imaging

INTRODUCTION/OBJECTIVES

First metatarsophalangeal joint (MTP) joint osteoarthritis (OA) is prevalent, although the pathology of this condition is poorly understood. This study aimed to determine if there were differences in magnetic resonance imaging (MRI) characteristics of the first MTP joint between individuals with and without first MTP joint OA.

METHOD

This cross-sectional study compared 22 participants with first MTP joint OA to 22 control participants without first MTP joint OA (matched for age, sex, and body mass index). Participants underwent MRI of their first MTP joint and osteophytes, bone marrow lesions, subchondral cysts, effusion-synovitis, joint space narrowing, and cartilage loss were documented using an atlas of first MTP joint OA. Associations of MRI characteristics with the presence of first MTP joint OA were then determined.

RESULTS

The presence of first MTP joint OA was associated with increased severity of osteophytes (dorsal metatarsal head, plantar metatarsal head, and dorsal proximal phalanx), bone marrow lesions (metatarsal head and proximal phalanx), cysts of the metatarsal head, effusion-synovitis (dorsal aspect), joint space narrowing (metatarsal-proximal phalanx; metatarsal-sesamoids), and cartilage loss. In contrast, there were no statistically significant associations for bone marrow lesions of the sesamoids, cysts of the proximal phalanx, or effusion-synovitis (plantar aspect).

CONCLUSIONS

Osteophytes, bone marrow lesions, subchondral cysts, effusion-synovitis, joint space narrowing, and cartilage loss are characteristic MRI features of first MTP joint OA. First MTP joint OA is a disease of multiple joint tissues and this has implications for the assessment and management of this condition. Key Points • First metatarsophalangeal joint osteoarthritis is a disease of multiple joint tissues. • Osteophytes, bone marrow lesions, subchondral cysts, effusion-synovitis, joint space narrowing, and cartilage loss are characteristic MRI features of first metatarsophalangeal joint osteoarthritis. • These findings have implications for the assessment and management of this condition.

Bone turnover and articular cartilage differences localized to subchondral cysts in knees with advanced osteoarthritis

OBJECTIVE

To investigate changes in bone structure, turnover, and articular cartilage localized in subchondral bone cyst (SBC) regions associated with knee osteoarthritis (OA).

METHODS

Tibial plateaus (n = 97) were collected from knee OA patients during total knee arthroplasty (TKA). SBCs were identified using micro-computed tomography, and the specimens were divided into non-cyst (n = 25) and bone cyst (n = 72) groups. Microstructure of subchondral bone was assessed using bone volume fraction (BV/TV), trabecular number (Tb.N), structure model index (SMI) and bone mineral density (BMD). In bone cyst group, the cyst subregion, which contained at least one cyst, and the peri-cyst subregion, which contained no cysts, were further selected for microstructure analysis. Articular cartilage damage was estimated using the Osteoarthritis Research Society International (OARSI) score. The numbers of TRAP(+) osteoclasts, Osterix(+) osteoprogenitors, Osteocalcin(+) osteoblasts and expression of SOX9 were evaluated by immunohistochemistry.

RESULTS

Bone cyst group presented higher BV/TV, Tb.N and SMI at subchondral bone than non-cyst group. Furthermore, cyst subregion displayed increased BV/TV and Tb.N but lower BMD and SMI than peri-cyst subregion. Histology revealed a higher OARSI score in bone cyst group. SBC exhibited a weak relationship with BV/TV, etc. The numbers of TRAP(+) osteoclasts, Osterix(+) osteoprogenitors, Osteocalcin(+) osteoblasts and expression of SOX9, were higher in bone cyst group.

CONCLUSION

SBCs within knee OA are characterized by focally increased bone turnover, altered bone structure and more severe articular cartilage damage. The increased bone turnover possibly contributes to altered bone structure localized in SBC areas, and thus aggravates articular cartilage degeneration.

Bone-cartilage interface crosstalk in osteoarthritis: potential pathways and future therapeutic strategies

Currently, osteoarthritis (OA) is considered a disease of the entire joint, which is not simply a process of wear and tear but rather abnormal remodelling and joint failure of an organ. The bone-cartilage interface is therefore a functioning synergistic unit, with a close physical association between subchondral bone and cartilage suggesting the existence of biochemical and molecular crosstalk across the OA interface. The crosstalk at the bone-cartilage interface may be elevated in OA in vivo and in vitro. Increased vascularisation and formation of microcracks associated with abnormal bone remodelling in joints during OA facilitate molecular transport from cartilage to bone and vice versa. Recent reports suggest that several critical signalling pathways and biological factors are key regulators and activate cellular and molecular processes in crosstalk among joint compartments. Therapeutic interventions including angiogenesis inhibitors, agonists/antagonists of molecules and drugs targeting bone remodelling are potential candidates for this interaction. This review summarised the premise for the presence of crosstalk in bone-cartilage interface as well as the current knowledge of the major signalling pathways and molecular interactions that regulate OA progression. A better understanding of crosstalk in bone-cartilage interface may lead to development of more effective strategies for treating OA patients.

Relationship between isokinetic strength and tibiofemoral joint space width changes after anterior cruciate ligament reconstruction

BACKGROUND

It has been hypothesized that quadriceps muscle weakness is directly associated with the onset and progression of posttraumatic osteoarthritis after anterior cruciate ligament (ACL) injury and reconstruction (ACLR). This relationship, however, has not been studied with a prospective approach that includes the use of tibiofemoral joint space width difference (JSW-D) measurements to characterize the onset of posttraumatic osteoarthritis before the clinical manifestation of the disease.

PURPOSE

To assess the relationship between thigh muscle strength and JSW-D at presurgery baseline and at 1- and 4-year follow-up after ACLR compared with healthy, noninjured participants of similar sex, age, body mass index, and activity level.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 39 unilateral ACL-injured patients and 32 healthy controls were followed prospectively. During each follow-up, JSW, isokinetic knee strength, single-legged hop, and clinical- and patient-oriented outcomes were assessed. At final follow-up, ACL-injured participants who had JSW-D values (considered as the injured minus normal knee) that were less than the 95% confidence interval of controls were considered to be in the ACLR-narrow group, while those with JSW-D values that fell within the confidence intervals were in the ACLR-normal group. Relationships were evaluated between ACLR groups and controls via multilevel regression, as well as Kruskal-Wallis tests for between-group comparisons at 4-year follow-up.

RESULTS

At 4-year follow-up, 30 participants (79%) were in the ACLR-normal group and 8 (21%) were in the ACLR-narrow group. At baseline, the extension, flexion, and extension/flexion ratio strength values for both ACLR groups were significantly lower than those of controls (P ≤ .05), while the ACLR-narrow group had significantly lower extension strength at 60 and 180 deg/s (P = .04 and .03, respectively), as well as extension/flexion ratio at 60 deg/s (P = .04) in comparison with the ACL-normal group. At 4-year follow-up, 60 deg/s extension strength deficits persisted in the ACLR-narrow group compared with controls and ACLR-normal participants (P = .01 and .04, respectively). Flexion strength at 180 and 300 deg/s was also significantly lower in the ACLR-narrow group compared with ACLR-normal (P = .02 and .04, respectively), as was single-legged hop distance (P = .04).

CONCLUSION

Strength deficits present within months after ACL injury and persist through 4 years after ACLR in participants with significantly narrowed JSW-D, compared with ACLR participants with normal JSW-D and controls. This study revealed a significant relationship between quadriceps strength loss that occurred soon after injury and JSW narrowing.

Pain in patients with equal radiographic grades of osteoarthritis in both knees: the value of gray scale ultrasound

OBJECTIVES

To investigate the association of ultrasound (US) features with pain and the functional scores in patients with equal radiographic grades of osteoarthritis (OA) in both knees.

METHODS

Fifty-six consecutive patients with knee OA: 85 symptomatic knees (81 knees with medial pain) and 27 asymptomatic knees, and 10 healthy patients without knee OA as a control were enrolled. US was done by two ultrasonographers blinded to patient diagnoses. US features were semiquantitatively scored (0-3) when appropriate.

RESULTS

In the OA group, common US findings were marginal osteophyte, suprapatellar synovitis, suprapatellar effusion (SPE), medial meniscus protrusion, medial compartment synovitis (MCS), lateral compartment synovitis, and Baker's cyst. Only SPE and MCS were significantly associated with knee pain. Visual analog pain scale (VAS) scores on motion were positively linearly associated with SPE and MCS (P < 0.01). Only MCS was degree-dependently associated with VAS scores at rest, the Western Ontario and McMaster Universities pain subscale, and the presence of medial knee pain (P < 0.01) after adjustments for age, gender, body mass index (BMI), radiographic grade, and other US features. In the control group, no US features were associated with knee pain.

CONCLUSIONS

US inflammation features, including SPE and MCS, were positively linearly associated with knee pain in motion. MCS was also degree-dependently associated with pain at rest and the presence of medial knee pain. These findings show that synovitis was one important predictive factor of pain. Further studies to confirm the association of US features and pain are warranted.

Magnetic resonance imaging of subchondral bone marrow lesions in association with osteoarthritis

OBJECTIVES

This nonsystematic literature review provides an overview of magnetic resonance imaging (MRI) of subchondral bone marrow lesions (BMLs) in association with osteoarthritis (OA), with particular attention to the selection of MRI sequences and semiquantitative scoring systems, characteristic morphology, and differential diagnosis. Histologic basis, natural history, and clinical significance are also briefly discussed.

METHODS

PubMed was searched for articles published up to 2011, using the keywords bone marrow lesion, osteoarthritis, magnetic resonance imaging, bone marrow edema, histology, pain, and subchondral.

RESULTS

BMLs in association with OA correspond to fibrosis, necrosis, edema, and bleeding of fatty marrow as well as abnormal trabeculae on histopathology. Lesions may fluctuate in size within a short time and are associated with the progression of articular cartilage loss and fluctuation of pain in knee OA. The characteristic subchondral edema-like signal intensity of BMLs should be assessed using T2-weighted, proton density-weighted, intermediate-weighted fat-suppressed fast spin echo or short tau inversion recovery. Several semiquantitative scoring systems are available to characterize and grade the severity of BMLs. Quantitative approaches have also been introduced. Differential diagnoses of degenerative BMLs include a variety of traumatic or nontraumatic pathologies that may appear similar to OA-related BMLs on MRI.

CONCLUSIONS

Subchondral BMLs are a common imaging feature of OA with clinical significance and typical signal alteration patterns, which can be assessed and graded by semiquantitative scoring systems using sensitive MRI sequences.

Rapidly progressive osteoarthritis: biomechanical considerations

An underlying hypothesis for rapid cartilage loss in patients with osteoarthritis (OA) is that perturbation from normal joint mechanics produces locally high biomechanical strains that exceed the material properties of the tissue, leading to rapid destruction. Several imaging findings are associated with focally high biomechanical forces and thus are potential candidates for predictive biomarkers of rapid OA progression. This article focuses on 3 aspects of knee biomechanics that have potential magnetic resonance imaging correlates, and which may serve as prognostic biomarkers: knee malalignment, meniscal dysfunction, and injury of the osteochondral unit.

Semiquantitative assessment of subchondral bone marrow edema-like lesions and subchondral cysts of the knee at 3T MRI: a comparison between intermediate-weighted fat-suppressed spin echo and Dual Echo Steady State sequences

BACKGROUND

Choice of appropriate MR pulse sequence is important for any research studies using imaging-derived data. The aim of this study was to compare semiquantitative assessment of subchondral bone marrow edema-like lesions and subchondral cysts using intermediate-weighted (IW) fat-suppressed (fs) spin echo and Dual Echo Steady State (DESS) sequences on 3 T MRI.

METHODS

Included were 201 subjects aged 35-65 with frequent knee pain. 3T MRI was performed with the same sequence protocol as in the Osteoarthritis Initiative (OAI). In a primary reading subchondral bone marrow edema-like lesions were assessed according to the WORMS system. Two hundred subregions with such lesions were randomly chosen. The extent of subchondral bone marrow edema-like lesions was re-evaluated separately using sagittal IW fs and DESS sequences according to WORMS. Lesion size and confidence of the differentiation between subchondral bone marrow edema-like lesions and subchondral cysts located within or adjacent to them was rated from 0 to 3. Wilcoxon signed-rank tests and chi-square statistics were used to examine differences between the two sequences.

RESULTS

Of 200 subchondral bone marrow edema-like lesions detected by IW fs sequence, 93 lesions (46.5%) were not depicted by the DESS sequence. The IW fs sequence depicted subchondral bone marrow edema-like lesions to a larger extent than DESS (p < 0.0001), and the opposite was true for subchondral cysts. Confidence scores for differentiation of the two types of lesions were not significantly different between the two sequences.

CONCLUSIONS

In direct comparison the IW fs sequence depicts more subchondral bone marrow edema-like lesions and better demonstrate the extent of their maximum size. The DESS sequence helps in the differentiation of subchondral bone marrow edema-like lesions and subchondral cysts. The IW fs sequence should be used for determination of lesion extent whenever the size of subchondral bone marrow edema-like lesions is the focus of attention.

Cyst-like lesions of the knee joint and their relation to incident knee pain and development of radiographic osteoarthritis: the MOST study

OBJECTIVE

To determine whether intra- and periarticular cyst-like lesions of the knee are associated with incident knee pain and incident radiographic knee osteoarthritis (OA).

DESIGN

The Multicenter Osteoarthritis (MOST) Study is a cohort of individuals who have or are at high risk for knee OA. Using a nested case-control study design, we investigated the associations of cyst-like lesions (Baker's, meniscal and proximal tibiofibular joint (PTFJ) cysts, and prepatellar and anserine bursitides) with (1) incident pain at 15- or 30-month follow-up and (2) incident radiographic OA at 30-month follow-up. Baseline cyst-like lesions were scored semiquantitatively using the Whole Organ Magnetic Resonance Imaging Score (WORMS). Conditional logistic regression models were used to assess the relation between these lesions and the outcomes, adjusting for potential confounding factors (i.e., cartilage loss, meniscal damage, bone marrow lesions, synovitis and joint effusion, which were also scored using WORMS).

RESULTS

Incident knee pain study included 157 cases and 336 controls. Prevalence of meniscal and PTFJ cysts in the case group was twice that in the control group [9 (6%) vs 9 (3%) and 9 (6%) vs 10 (3%), respectively]. Incident radiographic OA study included 149 cases and 298 controls. Prevalence of grade 2 Baker's cysts and PTFJ cysts in the case group was approximately four times that in the control group [16(11%) vs 9 (3%) and 6 (4%) vs 3 (1%), respectively]. However, none of the cyst-like lesions was associated with incident pain or radiographic OA after fully adjusted logistic regression analyses and correction of P-values for multiple comparisons.

CONCLUSION

None of the analyzed lesions was an independent predictor of incident knee pain or radiographic OA. Intra- and periarticular cyst-like lesions are likely to be a secondary phenomenon seen in painful or OA-affected knees, rather than a primary trigger for incident knee pain or radiographic OA.

Anatomical distribution of synovitis in knee osteoarthritis and its association with joint effusion assessed on non-enhanced and contrast-enhanced MRI

PURPOSE

To describe the anatomical distribution of synovitis and its association with joint effusion on non-enhanced and contrast-enhanced (CE) MRI in patients with knee osteoarthritis (OA).

METHODS

Baseline MRI was performed at 1.5T using axial proton density (PD)-weighted (w) fat suppressed (fs) and axial and sagittal T1-w fs CE sequences. Synovial enhancement was scored in nine articular subregions. Maximum synovial enhancement was grouped as absent (0), equivocal (1) and definite (2 and 3). Effusion was scored from 0 to 3 on the axial sequences. We described the anatomical distribution of synovitis, its association with effusion and compared assessment of effusion on T1-w fs CE and PD fs sequences.

RESULTS

111 subjects were included and examined by MRI. 89.2% of knees exhibited at least one subregion with a minimum grade 2 and 39.6% at the maximum of a grade 3. The commonest sites for definite synovitis were posterior to the posterior cruciate ligament (PCL) in 71.2% and in the suprapatellar region in 59.5% of all knees. On T1-w fs CE, 73.0% of knees showed any effusion. Definite synovitis in at least one location was present in 96.3% knees with an effusion and in 70.0% without an effusion. Higher grades of effusion were scored on the PD fs sequence.

CONCLUSION

Definite synovitis was present in the majority of knees with or without effusion with the commonest sites being posterior to the PCL and in the suprapatellar recess. Joint effusion as measured on PD fs images does not only represent effusion but also synovial thickening.

The bone marrow lesion in osteoarthritis

Osteoarthritis (OA) is considered a multifactorial disease whose development and progression may include several structural abnormalities aside from cartilage destruction. Bone marrow lesions (BMLs) have been reported to be associated with OA pathology, and several studies have advocated its close connection to the severity of joint structural alterations and pain, the main OA clinical manifestation. Hence, BMLs may not only affect subchondral bone and its neuronal and vascular structures but also negatively influence the adjacent tissues. Here, we analyze the pathophysiology and natural history of OA-associated BMLs and their potential relevance to the radiographic progression and severity of the disease. The notion that BMLs may be a precursor to additional articular abnormalities, can be a potential risk factor for development of OA, and may serve as an additional diagnostic tool and a therapeutic target are further discussed.