Change in cartilage morphometry: a sample of the progression cohort of the Osteoarthritis Initiative

Knee cartilage change on magnetic resonance imaging: Should we lump or split topographical regions? A 2-year study of data from the osteoarthritis initiative

OBJECTIVE

We challenge the paradigm that a simplistic approach evaluating anatomic regions (e.g., medial femur or tibia) is ideal for assessing articular cartilage loss on magnetic resonance (MR) imaging. We used a data-driven approach to explore whether specific topographical locations of knee cartilage loss may identify novel patterns of cartilage loss over time that current assessment strategies miss.

DESIGN

We assessed 60 location-specific measures of articular cartilage on a sample of 99 knees with baseline and 24-month MR images from the Osteoarthritis Initiative, selected as a group with a high likelihood to change. We performed factor analyses of the change in these measures in two ways: (1) summing the measures to create one measure for each of the six anatomically regional-based summary (anatomic regions; e.g., medial tibia) and (2) treating each location separately for a total of 60 measures (location-specific measures).

RESULTS

The first analysis produced three factors accounting for 66% of the variation in the articular cartilage changes that occur over 24 months of follow-up: (1) medial tibiofemoral, (2) medial and lateral patellar, and (3) lateral tibiofemoral. The second produced 20 factors accounting for 75% of the variance in cartilage changes. Twelve factors only involved one anatomic region. Five factors included locations from adjoining regions (defined by the first analysis; e.g., medial tibiofemoral). Three factors included articular cartilage loss from disparate locations.

CONCLUSIONS

Novel patterns of cartilage loss occur within each anatomic region and across these regions, including in disparate regions. The traditional anatomic regional approach is simpler to implement and interpret but may obscure meaningful patterns of change.

Relationship Between 2 Years of Muscle Strength Decrease and Volume Loss of Menisci and Cartilage According to Knee Pain in Mild and Moderate Knee Osteoarthritis

OBJECTIVE

The aim of the study is to explore the relationship between 2-yr changes in muscle strength and cartilage according to knee pain in mild and moderate knee osteoarthritis.

DESIGN

Two hundred seventy-nine participants were retrospectively obtained from the Osteoarthritis Initiative. Western Ontario McMaster University and Knee Injury and Osteoarthritis Outcome Score were used to assess pain and function. Five muscles strength (maximum extensor and flexor, normalized maximum extensor and flexor, and extensor/flexor ratio) were measured from isometric strength test. Menisci and cartilage volumes were measured from magnetic resonance imaging to assess 2 yr of osteoarthritis progression.

RESULTS

Mild and moderate knee osteoarthritis progression was characterized by patellofemoral cartilage loss and meniscal degeneration. For WOMAC pain >2 participants, decrease in extensor strength and normalized extensor strength were positively correlated with medial meniscus volume loss (r = 0.261, P = 0.021; r = 0.232, P = 0.041, respectively). The extensor/flexor ratio changes were positively associated with Western Ontario McMaster University function changes (r = 0.291, P = 0.013) over 2 yrs.

CONCLUSIONS

The study observed a positive correlation between quadriceps strength decrease and medial meniscus degeneration in mild and moderate knee osteoarthritis patients with Western Ontario McMaster University pain >2. These findings suggested quadriceps-hamstrings balance possibly plays a protective role in knee function for participants with weaker quadriceps and severe pain.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME.

CME OBJECTIVES

Upon completion of this article, the reader should be able to: 1): Determine the effect of knee extensor muscle strength changes on the medial and lateral meniscus, tibia, and medial and lateral femoral cartilage over 2 yrs in mild to moderate knee osteoarthritis patients; 2): Describe the correlation of knee extensor strength with the medial and lateral meniscus, tibia, and medial and lateral femoral cartilage at different WOMAC-pain levels; and 3): Discuss the relationship between changes in muscle strength and changes in meniscus and cartilage volume and WOMAC pain scores over 2 yrs in mild to moderate knee osteoarthritis patients.

LEVEL

Advanced.

ACCREDITATION

The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s) ™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Deep learning applications in osteoarthritis imaging

Deep learning (DL) is one of the most exciting new areas in medical imaging. This article will provide a review of current applications of DL in osteoarthritis (OA) imaging, including methods used for cartilage lesion detection, OA diagnosis, cartilage segmentation, and OA risk assessment. DL techniques have been shown to have similar diagnostic performance as human readers for detecting and grading cartilage lesions within the knee on MRI. A variety of DL methods have been developed for detecting and grading the severity of knee OA and various features of knee OA on X-rays using standardized classification systems with diagnostic performance similar to human readers. Multiple DL approaches have been described for fully automated segmentation of cartilage and other knee tissues and have achieved higher segmentation accuracy than currently used methods with substantial reductions in segmentation times. Various DL models analyzing baseline X-rays and MRI have been developed for OA risk assessment. These models have shown high diagnostic performance for predicting a wide variety of OA outcomes, including the incidence and progression of radiographic knee OA, the presence and progression of knee pain, and future total knee replacement. The preliminary results of DL applications in OA imaging have been encouraging. However, many DL techniques require further technical refinement to maximize diagnostic performance. Furthermore, the generalizability of DL approaches needs to be further investigated in prospective studies using large image datasets acquired at different institutions with different imaging hardware before they can be implemented in clinical practice and research studies.

The influence of zinc and iron intake on osteoarthritis patients' subchondral sclerosis progression: A prospective observational study using data from the osteoarthritis Initiative

Objective

The purpose of this investigation was to elucidate the relationship between the zinc and iron intake and the advancement of subchondral sclerosis among patients with osteoarthritis (OA). The goal was to establish personalized, nutritionally-informed strategies designed to retard the progression of subchondral sclerosis and conserve joint structure.

Methods

For the purposes of this research, we derived data from the Bone Ancillary Study (BAS), a constituent study of the Osteoarthritis Initiative (OAI). The intake of zinc and iron was evaluated via a food frequency questionnaire. Magnetic Resonance Imaging trabecular morphometry was employed to ascertain the microarchitecture of the subchondral bone. For the analysis of collected data, we employed logistic regression along with generalized additive models (GAMs).

Results

The participant cohort was comprised of 474 OA patients (216 females, 258 males, mean [SD] age 64.1[9.2]). Notably, an increment in zinc consumption was linked with a significantly reduced likelihood of deterioration in Tb.N (OR = 0.967, 95 % CI, 0.939-0.996, P-value = 0.026), Tb.Th (OR = 0.958, 95 % CI, 0.929-0.989, P-value = 0.008), and Tb.Sp (OR = 0.967, 95 % CI, 0.939-0.996, P-value = 0.013). An elevation in iron intake seemed to enhance the risk of subchondral sclerosis, as indicated by the GAM. Subgroup analysis revealed an interaction between the effectiveness of zinc intake and factors such as gender, age, radiographic severity, and macronutrient consumption. An increased intake of calcium amplified the beneficial impact of zinc on subchondral sclerosis.

Conclusions

Our findings indicate a positive association between elevated zinc intake and a slowdown in the progression of subchondral sclerosis in OA patients, notably among females, middle-aged individuals, and those with higher calcium and magnesium intake. Conversely, a higher iron intake might intensify subchondral sclerosis. These results suggest that personalized, diet-based interventions focusing on zinc consumption, in tandem with adequate calcium intake, could potentially decelerate the progression of subchondral sclerosis in individuals afflicted with OA.

Towards Automatic Cartilage Quantification in Clinical Trials - Continuing from the 2019 IWOAI Knee Segmentation Challenge

Objective

To evaluate whether the deep learning (DL) segmentation methods from the six teams that participated in the IWOAI 2019 Knee Cartilage Segmentation Challenge are appropriate for quantifying cartilage loss in longitudinal clinical trials.

Design

We included 556 subjects from the Osteoarthritis Initiative study with manually read cartilage volume scores for the baseline and 1-year visits. The teams used their methods originally trained for the IWOAI 2019 challenge to segment the 1130 knee MRIs. These scans were anonymized and the teams were blinded to any subject or visit identifiers. Two teams also submitted updated methods. The resulting 9,040 segmentations are available online.The segmentations included tibial, femoral, and patellar compartments. In post-processing, we extracted medial and lateral tibial compartments and geometrically defined central medial and lateral femoral sub-compartments. The primary study outcome was the sensitivity to measure cartilage loss as defined by the standardized response mean (SRM).

Results

For the tibial compartments, several of the DL segmentation methods had SRMs similar to the gold standard manual method. The highest DL SRM was for the lateral tibial compartment at 0.38 (the gold standard had 0.34). For the femoral compartments, the gold standard had higher SRMs than the automatic methods at 0.31/0.30 for medial/lateral compartments.

Conclusion

The lower SRMs for the DL methods in the femoral compartments at 0.2 were possibly due to the simple sub-compartment extraction done during post-processing. The study demonstrated that state-of-the-art DL segmentation methods may be used in standardized longitudinal single-scanner clinical trials for well-defined cartilage compartments.

Quadriceps muscle strength at 2 years following anterior cruciate ligament reconstruction is associated with tibiofemoral joint cartilage volume

PURPOSE

Quadriceps strength deficits following anterior cruciate ligament reconstruction (ACLR) are linked to altered lower extremity biomechanics, tibiofemoral joint (TFJ) space narrowing and cartilage composition changes. It is unknown, however, if quadriceps strength is associated with cartilage volume in the early years following ACLR prior to the onset of posttraumatic osteoarthritis (OA) development. The purpose of this cross-sectional study was to examine the relationship between quadriceps muscle strength (peak and across the functional range of knee flexion) and cartilage volume at ~ 2 years following ACLR and determine the influence of concomitant meniscal pathology.

METHODS

The involved limb of 51 ACLR participants (31 isolated ACLR; 20 combined meniscal pathology) aged 18-40 years were tested at 2.4 ± 0.4 years post-surgery. Isokinetic knee extension torque generated in 10° intervals between 60° and 10° knee flexion (i.e. 60°-50°, 50°-40°, 40°-30°, 30°-20°, 20°-10°) together with peak extension torque were measured. Tibial and patellar cartilage volumes were measured using magnetic resonance imaging (MRI). The relationships between peak and angle-specific knee extension torque and MRI-derived cartilage volumes were evaluated using multiple linear regression.

RESULTS

In ACLR participants with and without meniscal pathology, higher knee extension torques at 60°-50° and 50°-40° knee flexion were negatively associated with medial tibial cartilage volume (p < 0.05). No significant associations were identified between peak concentric or angle-specific knee extension torques and patellar cartilage volume.

CONCLUSION

Higher quadriceps strength at knee flexion angles of 60°-40° was associated with lower cartilage volume on the medial tibia ~ 2 years following ACLR with and without concomitant meniscal injury. Regaining quadriceps strength across important functional ranges of knee flexion after ACLR may reduce the likelihood of developing early TFJ cartilage degenerative changes.

LEVEL OF EVIDENCE

III.

Role of Lower Limb Muscle Strength in Knee Osteoarthritis Progression for Patients With Mild and Moderate Knee Osteoarthritis

OBJECTIVE

We aimed to elucidate the association of lower limb muscle strength with the volume loss of cartilages/menisci for patients with mild and moderate knee osteoarthritis.

DESIGN

One hundred seventy individuals with mild and moderate knee osteoarthritis were included from the Osteoarthritis Initiative database. Five muscle strength variables were measured from isometric strength test. The measurement of volume on medial and lateral menisci and seven subregional cartilages from knee magnetic resonance scans were used for assessing 2-yr osteoarthritis progression.

RESULTS

Along with the decreased lower limb muscle strength, the volume of patellar cartilage, medial meniscus, and lateral meniscus decreased more than cartilage on tibia and weight-bearing femoral condyle. However, the cartilage volume on the entire medial and lateral femoral condyle increased significantly. The maximum quadricep strength was the most sensitive muscle strength variable, and we found that it was more positively correlated with lateral meniscus volume than with other subregions at baseline and 24-mo follow-up.

CONCLUSIONS

This study shows the relationship between lower limb muscle strength and volumes of cartilage and meniscus for patients with mild and moderate knee osteoarthritis. In addition, our study indicates a biomechanical mechanism of quadricep strength and meniscus-related knee dynamic stability in progression of mild-to-moderate knee osteoarthritis.

Novel Framework for Measuring Whole Knee Osteoarthritis Progression Using Magnetic Resonance Imaging

OBJECTIVE

We developed and validated a set of composite scores that combine quantitative magnetic resonance imaging (MRI)-based measurements of hyaline cartilage damage, bone marrow lesions (BMLs), and effusion-synovitis into composite scores.

METHODS

We selected 300 participants (n = 100 for development cohort; n = 200 for validation cohort) from the Osteoarthritis Initiative with complete clinical, radiographic, and MRI data at baseline and 24 months. We used semiautomated programs to quantify tibiofemoral and patellar cartilage damage, BML volume, and whole-knee effusion-synovitis volume. The candidate composite scores were formed by summing changes from baseline to 24 months based on prespecified methods. We evaluated the candidate composite scores for 1) the ability to differentiate groups with and without knee osteoarthritis progression (17 radiographic and patient-reported definitions), 2) sensitivity to change (standardized response means), and 3) relative performance relating to legacy outcome measures of knee osteoarthritis progression.

RESULTS

Three of 13 developed composite scores qualified for testing in the validation cohort (ranked by sensitivity to change): whole-knee cumulative cartilage damage, unweighted total knee score, and BML plus effusion-synovitis volume. Change in cumulative cartilage damage associated with radiographic progression (Kellgren/Lawrence grade: odds ratio [OR] 1.84; joint space width progression: OR 2.11). Changes in the unweighted total knee score (OR 1.97) and BML plus effusion-synovitis score (OR 1.92) associated with Western Ontario and McMaster Universities Osteoarthritis Index knee pain progression.

CONCLUSION

Two composite scores emerged, reflecting discrete domains of knee osteoarthritis progression. First, cumulative damage, which is measured by a whole-knee cartilage damage score, reflects the damage accrued over time. Second, dynamic disease activity, which is measured by a BML plus effusion-synovitis score, relates to changes in a patient's state of disease and symptoms.

Deep learning-based segmentation of knee MRI for fully automatic subregional morphological assessment of cartilage tissues: Data from the Osteoarthritis Initiative

Morphological changes in knee cartilage subregions are valuable imaging-based biomarkers for understanding progression of osteoarthritis, and they are typically detected from magnetic resonance imaging (MRI). So far, accurate segmentation of cartilage has been done manually. Deep learning approaches show high promise in automating the task; however, they lack clinically relevant evaluation. We introduce a fully automatic method for segmentation and subregional assessment of articular cartilage, and evaluate its predictive power in context of radiographic osteoarthritis progression. Two data sets of 3D double-echo steady-state (DESS) MRI derived from the Osteoarthritis Initiative were used: first, n = 88; second, n = 600, 0-/12-/24-month visits. Our method performed deep learning-based segmentation of knee cartilage tissues, their subregional division via multi-atlas registration, and extraction of subregional volume and thickness. The segmentation model was developed and assessed on the first data set. Subsequently, on the second data set, the morphological measurements from our and the prior methods were analyzed in correlation and agreement, and, eventually, by their discriminative power of radiographic osteoarthritis progression over 12 and 24 months, retrospectively. The segmentation model showed very high correlation (r > 0.934) and agreement (mean difference < 116 mm³ ) in volumetric measurements with the reference segmentations. Comparison of our and manual segmentation methods yielded r = 0.845-0.973 and mean differences = 262-501 mm³ for weight-bearing cartilage volume, and r = 0.770-0.962 and mean differences = 0.513-1.138 mm for subregional cartilage thickness. With regard to osteoarthritis progression, our method found most of the significant associations identified using the manual segmentation method, for both 12- and 24-month subregional cartilage changes. The method may be effectively applied in osteoarthritis progression studies to extract cartilage-related imaging biomarkers.

Prediction models for the risk of total knee replacement: development and validation using data from multicentre cohort studies

Background

Few prognostic prediction models for total knee replacement are available, and the role of radiographic findings in predicting its use remains unclear. We aimed to develop and validate predictive models for total knee replacement and to assess whether adding radiographic findings improves predictive performance.

Methods

We identified participants with recent knee pain (in the past 3 months) in the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI). The baseline visits of MOST were initiated in 2003 and of OAI were initiated in 2004. We developed two predictive models for the risk of total knee replacement within 60 months of follow-up by fitting Cox proportional hazard models among participants in MOST. The first model included sociodemographic and anthropometric factors, medical history, and clinical measures (referred to as the clinical model). The second model added radiographic findings into the predictive model (the radiographic model). We evaluated each model's discrimination and calibration performance and assessed the incremental value of radiographic findings using both category-free net reclassification improvement (NRI) and integrated discrimination improvement (IDI). We tuned the models and externally validated them among participants in OAI.

Findings

We included 2658 participants from MOST (mean age 62·4 years [SD 8·1], 1646 [61·9%] women) in the training dataset and 4060 participants from OAI (mean age 60·9 years [9·1], 2379 [58·6%] women) in the validation dataset. 290 (10·9%) participants in the training dataset and 174 (4·3%) in the validation dataset had total knee replacement. The retained predictive variables included in the clinical model were age, sex, race, history of knee arthroscopy, frequent knee pain, current use of analgesics, current use of glucosamine, body-mass index, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score, and the most predictive factors were age, race, and WOMAC pain score. The retained predictive variables in the radiographic model were age, sex, race, frequent knee pain, current use of analgesics, WOMAC pain score, and Kellgren-Lawrence grade, and the most predictive factors were Kellgren-Lawrence grade, race, and age. The C-statistic was 0·79 (95% CI 0·76-0·81) for the clinical model and 0·87 (0·85-0·99) for the radiographic model in the training dataset. The calibration slope was 0·95 (95% CI 0·86-1·05) and 0·96 (0·87-1·04), respectively. Adding radiograph findings significantly improved predictive performance with an NRI of 0·43 (95% CI 0·38-0·50) and IDI of 0·14 (95% CI: 0·10-0·18). Both models, with tuned coefficients, showed a good predictive performance among participants in the validation dataset.

Interpretation

The risk of total knee replacement can be predicted based on common risk factors with good discrimination and calibration. Additionally, adding radiographic findings of knee osteoarthritis into the model substantially improves its predictive performance.

Funding

National Natural Science Foundation of China, National Key Research and Development Program, and Beijing Municipal Science & Technology Commission.

Prognostic factors for tibiofemoral and patellofemoral osteoarthritis 32-37 years after anterior cruciate ligament injury managed with early surgical repair or rehabilitation alone

OBJECTIVE

Explore prognostic factors for tibiofemoral (TFJ) and patellofemoral (PFJ) radiographic osteoarthritis (ROA) and 'symptoms plus ROA' (SOA), 32-37 years following anterior cruciate ligament (ACL) injury.

DESIGN

Exploratory analysis, longitudinal cohort.

METHODS

In 1980-1985, 251 patients aged 15-40 years with acute ACL rupture were allocated to early augmented or non-augmented repair (5 ± 4 days post-injury) plus rehabilitation, or rehabilitation alone. 127 of 190 participants who completed follow-up questionnaires were eligible. We classified ROA as TFJ/PFJ K&L Grade ≥2, and SOA as ROA plus pain and/or symptoms. Multivariable age-adjusted logistic regression investigated potential prognostic factors (assessed at 4 ± 1 year follow-up: ACL treatment, isokinetic quadriceps/hamstrings strength, single-leg-hop for distance, knee flexion/extension deficit, knee laxity, Tegner Activity Scale, Lysholm Scale; sex, baseline meniscus status).

RESULTS

127 patients were aged 58 ± 6 years; BMI 27 ± 4 kg/m²; 28% female; 59% had TFJ-ROA, 48% had TFJ-SOA (including n = 9 knee-arthroplasties), 36% had PFJ-ROA; 27% had PFJ-SOA. Baseline meniscus surgery was a prognostic factor for TFJ-ROA (multivariable age-adjusted odds ratio (95% CI): 3.0 (1.2, 7.8)). A single-leg-hop limb symmetry index (LSI) < 90% was a prognostic factor for PFJ-ROA (5.1 (1.4, 18.7)) and PFJ-SOA (4.9 (1.2, 19.7)). Hamstrings strength LSI <90% was a prognostic factor for PFJ-SOA (5.0 (1.3, 19.3)). ACL treatment with rehabilitation-alone was associated with an 80% reduction in the odds of PFJ-SOA (0.2 (0.1-0.7)), compared with early ACL-repair.

CONCLUSIONS

These findings are hypothesis generating, research is needed to determine whether ACL-injured individuals with these characteristics benefit from interventions to prevent or delay the onset of osteoarthritis.

Longitudinal changes in location-specific cartilage thickness and T2 relaxation-times after posterior cruciate ligament reconstruction for isolated and multiligament injury

BACKGROUND

Knee cartilage undergoes pathological changes after anterior cruciate ligament rupture. However, little is known about the development and progression of structural pathology after posterior cruciate ligament (PCL) injury. This study aimed to determine the location-specific longitudinal changes in knee cartilage morphology (thickness) and composition (T2 relaxation-times) after PCL rupture and reconstruction (PCLR) and compare these to uninjured controls.

METHODS

Fifteen adults (mean age 39 years (standard deviation 10), 12 men) with PCLR for isolated and multiligment injury had MRIs acquired at a minimum 5 years post-PCLR and 1 year later. Location-specific changes in knee cartilage thickness and T2 relaxation-times were determined quantitatively after segmentation, and compared with annualised cartilage changes in 13 active controls (mean age 45 years (standard deviation 4), 6 men).

FINDINGS

Following PCLR, the annual loss of cartilage thickness was greatest in the medial femoral condyle (mean -4.0%, 95% confidence interval [95% CI] -6.7, -1.4), medial tibia (mean -3.7%, 95% CI -6.1, -1.3), and patella (mean -3.2%, 95% CI -4.7, -1.6). In the medial femoral condyle and trochlea, the PCLR group lost significantly more cartilage thickness than uninjured controls (mean difference -3.7%, 95% CI -0.9, -6.5; and -1.8%, 95% CI -0.1, -3.6, respectively). Deep and superficial zone T2 relaxation-times were relatively constant over time, without longitudinal differences between PCLR and control knees.

INTERPRETATION

PCL reconstructed knees displayed substantially greater rates of cartilage loss in the medial tibiofemoral and patellofemoral compartments compared to uninjured controls, highlighting that the process of degeneration remains active many years after injury.

Loss of patellofemoral cartilage thickness over 5 years following ACL injury depends on the initial treatment strategy: results from the KANON trial

OBJECTIVES

To evaluate changes in patellofemoral cartilage thickness over 5 years after anterior cruciate ligament (ACL) injury and to determine the impact of treatment strategy.

METHODS

121 adults (ages 18-35 years, 26% women) had an ACL injury and participated in the KANON randomised controlled trial. Of those, 117 had available MRIs at baseline (<4 weeks post-ACL rupture) and at least one follow-up measurement (2, 5 years). Patellofemoral cartilage thickness was analysed by manual segmentation (blinded to acquisition order). Patellar, trochlear and total patellofemoral cartilage thickness changes were compared between as-randomised (rehabilitation+early ACL reconstruction (ACLR) (n=59) vs rehabilitation+optional delayed ACLR (n=58)) and as-treated groups (rehabilitation+early ACLR (n=59) vs rehabilitation +delayed ACLR (n=29) vs rehabilitation alone (n=29)).

RESULTS

Patellofemoral cartilage thickness decreased -58 µm (95% CI -104 to -11 µm) over 5 years post-ACL rupture, with the greatest loss observed in trochlea during the first 2 years. Participants randomised to rehabilitation+early ACLR had significantly greater loss of patellar cartilage thickness compared with participants randomised to rehabilitation+optional delayed ACLR over the first 2 years (-25 µm (-52, 1 µm) vs +14 µm (-6 to 34 µm), p=0.02) as well as over 5 years (-36 µm (-78 to 5 µm) vs +18 µm (-7, 42 µm), p=0.02). There were no statistically significant differences in patellofemoral cartilage thickness changes between as-treated groups.

CONCLUSION

Patellofemoral (particularly trochlear) cartilage thickness loss was observed in young adults following acute ACL rupture. Early ACLR was associated with greater patellofemoral (particularly patellar) cartilage thickness loss over 5 years compared with optional delayed ACLR, indicating that early surgical intervention may be associated with greater short-term structural patellofemoral cartilage deterioration compared with optional delayed surgery.

TRIAL REGISTRATION NUMBER

ISRCTN84752559; Post-results.

Influence of Obstructive Sleep Apnea in the Functional Aspects of Patients With Osteoarthritis

STUDY OBJECTIVES

It has been demonstrated in recent studies that obstructive sleep apnea (OSA) is the most prevalent sleep disorder in patients with osteoarthritis (OA), and thus the current study aimed to investigate the influence of OSA on knee extensor torque, pain, stiffness, and physical function in men with low-grade knee OA.

METHODS

The study included 60 male volunteers, aged 40 to 70 years, allocated into four groups: Group 1 (G1) Control (n = 15): without OA and without OSA; Group 2 (G2) (n = 15): with OA and without OSA; Group 3 (G3) (n = 15): without OA and with OSA; and Group 4 (G4) (n = 15) with OA and with OSA. All volunteers were examined using knee radiographs and polysomnography, responded to the Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaire, and completed a test on an isokinetic dynamometer to evaluate peak isometric knee extensor torque, both concentric and eccentric (90°/s and 180°/s).

RESULTS

Regarding the data from the WOMAC questionnaire (for pain, stiffness, and physical function), it was observed that G4 showed higher values compared to G1 or G3. For the concentric isometric and isokinetic peak knee extensor torque, lower values were observed in G4 compared to G1 or G3.

CONCLUSIONS

Patients who have knee OA in the early grades, when associated with OSA, have higher changes of the peak extensor torque, pain, stiffness, and physical function, compared with patients who did not have OSA.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Identifier: NCT01422967, Title: Changes Of Sleep on the Sensoriomotor and Cytokine In Patients With Osteoarthritis, URL: https://clinicaltrials.gov/ct2/show/NCT01422967.

Anatomically Standardized Maps Reveal Distinct Patterns of Cartilage Thickness With Increasing Severity of Medial Compartment Knee Osteoarthritis

While cartilage thickness alterations are a central element of knee osteoarthritis (OA), differences among disease stages are still incompletely understood. This study aimed to quantify the spatial-variations in cartilage thickness using anatomically standardized thickness maps and test if there are characteristic patterns in patients with different stages of medial compartment knee OA. Magnetic resonance images were acquired for 75 non-OA and 100 OA knees of varying severities (Kellgren and Lawrence (KL) scores 1-4). Three-dimensional cartilage models were reconstructed and a shape matching technique was applied to convert the models into two-dimensional anatomically standardized thickness maps. Difference thickness maps and statistical parametric mapping were used to compare the four OA and the non-OA subgroups. This analysis showed distinct thickness patterns for each clinical stage that formed a coherent succession from the non-OA to the KL 4 subgroups. Interestingly, the only significant difference for early stage (KL 1) was thicker femoral cartilage. With increase in disease severity, typical patterns developed, including thinner cartilage in the anterior area of the medial condyle (significant for KL 3 and 4) and thicker cartilage in the posterior area of the medial and lateral condyles (significant for all OA subgroups). The tibial patterns mainly consisted of thinner cartilage for both medial and lateral compartments (significant for KL 2-4). Comparing anatomically standardized maps allowed identifying patterns of thickening and thinning over the entire cartilage surface, consequently improving the characterization of thickness differences associated with OA. The results also highlighted the value of anatomically standardized maps to analyze spatial variations in cartilage thickness. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2442-2451, 2017.

Five-minute knee MRI for simultaneous morphometry and T2 relaxometry of cartilage and meniscus and for semiquantitative radiological assessment using double-echo in steady-state at 3T

BACKGROUND

Biomarkers for assessing osteoarthritis activity necessitate multiple MRI sequences with long acquisition times.

PURPOSE

To perform 5-minute simultaneous morphometry (thickness/volume measurements) and T₂ relaxometry of both cartilage and meniscus, and semiquantitative MRI Osteoarthritis Knee Scoring (MOAKS).

STUDY TYPE

Prospective.

SUBJECTS

Fifteen healthy volunteers for morphometry and T₂ measurements, and 15 patients (five each Kellgren-Lawrence grades 0/2/3) for MOAKS assessment.

FIELD STRENGTH/SEQUENCE

A 5-minute double-echo steady-state (DESS) sequence was evaluated for generating quantitative and semiquantitative osteoarthritis biomarkers at 3T.

ASSESSMENT

Flip angle simulations evaluated tissue signals and sensitivity of T₂ measurements. Morphometry and T₂ reproducibility was compared against morphometry-optimized and relaxometry-optimized sequences. Repeatability was assessed by scanning five volunteers twice. MOAKS reproducibility was compared to MOAKS derived from a clinical knee MRI protocol by two readers.

STATISTICAL TESTS

Coefficients of variation (CVs), concordance confidence intervals (CCI), and Wilcoxon signed-rank tests compared morphometry and relaxometry measurements with their reference standards. DESS MOAKS positive percent agreement (PPA), negative percentage agreement (NPA), and interreader agreement was calculated using the clinical protocol as a reference. Biomarker variations between Kellgren-Lawrence groups were evaluated using Wilcoxon rank-sum tests.

RESULTS

Cartilage thickness (P = 0.65), cartilage T₂ (P = 0.69), and meniscus T₂ (P = 0.06) did not significantly differ from their reference standard (with a 20° DESS flip angle). DESS slightly overestimated meniscus volume (P < 0.001). Accuracy and repeatability CVs were <3.3%, except the meniscus T₂ accuracy (7.6%). DESS MOAKS had substantial interreader agreement and high PPA/NPA values of 87%/90%. Bone marrow lesions and menisci had slightly lower PPAs. Cartilage and meniscus T₂ , and MOAKS (cartilage surface area, osteophytes, cysts, and total score) was higher in Kellgren-Lawrence groups 2 and 3 than group 0 (P < 0.05).

DATA CONCLUSION

The 5-minute DESS sequence permits MOAKS assessment for a majority of tissues, along with repeatable and reproducible simultaneous cartilage and meniscus T₂ relaxometry and morphometry measurements.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1328-1341.

Baseline knee adduction moment interacts with body mass index to predict loss of medial tibial cartilage volume over 2.5 years in knee Osteoarthritis

This study aimed to determine the extent to which changes over 2.5 years in medial knee cartilage thickness and volume were predicted by: (1) Peak values of the knee adduction (KAM) and flexion moments; and (2) KAM impulse and loading frequency, representing cumulative load, after controlling for age, sex and body mass index (BMI). Adults with clinical knee osteoarthritis participated. At baseline and approximately 2.5 years follow-up, cartilage thickness and volume of the medial tibia and femur were segmented from magnetic resonance imaging scans. Gait kinematics and kinetics, and daily knee loading frequency were also collected at baseline. Multiple linear regressions predicted changes in cartilage morphology from baseline gait mechanics. Data were collected from 52 participants (41 women) [age 61.0 (6.9) y; BMI 28.5 (5.7) kg/m² ] over 2.56 (0.51) years. There were significant KAM peak-by-BMI (p = 0.023) and KAM impulse-by-BMI (p = 0.034) interactions, which revealed that larger joint loads in those with higher BMIs were associated with greater loss of medial tibial cartilage volume. In conclusion, with adjustments for age, sex, and cartilage measurement at baseline, large magnitude KAM peak and KAM impulse each interacted with BMI to predict loss of cartilage volume of the medial tibia over 2.5 years among individuals with knee osteoarthritis. These data suggest that, in clinical knee osteoarthritis, exposure to large KAMs may be detrimental to cartilage in those with larger BMIs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2476-2483, 2017.

EULAR recommendations for the use of imaging in the clinical management of peripheral joint osteoarthritis

The increased information provided by modern imaging has led to its more extensive use. Our aim was to develop evidence-based recommendations for the use of imaging in the clinical management of the most common arthropathy, osteoarthritis (OA). A task force (including rheumatologists, radiologists, methodologists, primary care doctors and patients) from nine countries defined 10 questions on the role of imaging in OA to support a systematic literature review (SLR). Joints of interest were the knee, hip, hand and foot; imaging modalities included conventional radiography (CR), MRI, ultrasonography, CT and nuclear medicine. PubMed and EMBASE were searched. The evidence was presented to the task force who subsequently developed the recommendations. The strength of agreement for each recommendation was assessed. 17 011 references were identified from which 390 studies were included in the SLR. Seven recommendations were produced, covering the lack of need for diagnostic imaging in patients with typical symptoms; the role of imaging in differential diagnosis; the lack of benefit in monitoring when no therapeutic modification is related, though consideration is required when unexpected clinical deterioration occurs; CR as the first-choice imaging modality; consideration of how to correctly acquire images and the role of imaging in guiding local injections. Recommendations for future research were also developed based on gaps in evidence, such as the use of imaging in identifying therapeutic targets, and demonstrating the added value of imaging. These evidence-based recommendations and related research agenda provide the basis for sensible use of imaging in routine clinical assessment of people with OA.

Role of physical activity in cartilage damage progression of subjects with baseline full-thickness cartilage defects in medial tibiofemoral compartment: data from the Osteoarthritis Initiative

OBJECTIVE

To assess the association between physical activity and cartilage damage progression in medial tibiofemoral compartment (MTFC) using 2-year follow-up magnetic resonance imaging (MRI) in subjects with denuded areas of subchondral bone (dABs) at the central weight-bearing medial femur (cMF) at baseline MRI examination.

METHODS

One hundred subjects from the Osteoarthritis Initiative (OAI) progression cohort with dABs at the cMF at 3T MRI at baseline (51% men; mean age 62.2 years, range 45-79) were included. Sagittal 3D dual-echo steady-state with water excitation images were used to assess 2-year MTFC cartilage change. Associations between 2-year average Physical Activity Scale for the Elderly (PASE) and 2-year MTFC cartilage change were assessed by linear regression analysis. Subgroup analyses were performed.

RESULTS

No associations between PASE and 2-year MTFC cartilage change were observed in the entire cohort. Similarly, in the subgroup with cartilage loss during the 2 years, the non-refuted confidence intervals for the regression coefficients were tightly clustered around the null value (regression coefficients for: mean cMF.ThCtAB = -0.00059; 98.75% CI: -0.00130 to 0.00012), cMF.dAB% = 0.02176; 98.75% CI: -0.02514 to 0.06865, Mean MT.ThCtAB = -0.00013; 98.75% CI: -0.00064 to 0.00038, MT.dAB% = 0.02543; 98.75% CI: -0.01485 to 0.06571.

CONCLUSION

In the entire group of subjects with dABs at the cMF at baseline, no association between physical activity and 2-year MTFC cartilage change was detected. Due to the limited sample size of our study, small-sized effects may not have been detected in our study.

MRI measurement on intercondylar notch after anterior cruciate ligament rupture and its correlation

The knee joint is extremely susceptible to injury, which is usually identified by magnetic resonance imaging (MRI). In the present study, MRI was applied to quantitatively detect the association between anterior cruciate ligament (ACL) rupture and anatomic morphologic changes of the intercondylar notch. Forty patients with unilateral ACL rupture who were treated between July, 2013 and October, 2014 were enrolled in the present study. The patients were divided into the observation (affected side) and control (healthy side) groups. MRI measurements were undertaken based on parameters associated with intercondylar notch of double knee joints. The results showed that intercondylar notch width (ICW) in the observation group was significantly smaller than that in the control group, and differences were statistically significant (P<0.05). Differences on the intercondylar notch height and femoral condyle width [epicondylar width (EW)] between the two groups were not statistically significant (P>0.05). Notch width index (NWI) and notch shape index (NSI) in the observation group were significantly less than those in the control group and differences were statistically significant (P<0.05). Differences of Lysholm and Tegner scoring between the two groups were not statistically significant (P>0.05). The differential value of ICW in the observation group was 2.6±1.3 mm and the ACL rupture time of the affected knee was 20.4±1.3 months on average. The correlation was statistically significant (P<0.05). The correlation of Lysholm scoring, Tegner scoring and intercondylar notch stenosis degree on the affected knee was not statistically significant (P>0.05). In conclusion, after ACL rupture, ICW on the affected knee had significant stenosis, NSI and NWI were significantly reduced and the stenosis degree was aggravated with the prolongation of course. By contrast, Lysholm and Tegner scoring of patients with different degrees of stenosis had no correlation.

Scan-rescan precision of subchondral bone curvature maps from routine 3D DESS water excitation sequences: Data from the Osteoarthritis Initiative

BACKGROUND

Subchondral bone (SCB) undergoes changes in the shape of the articulating bone surfaces and is currently recognized as a key target in osteoarthritis (OA) treatment. The aim of this study was to present an automated system that determines the curvature of the SCB regions of the knee and to evaluate its cross-sectional and longitudinal scan-rescan precision

METHODS

Six subjects with OA and six control subjects were selected from the Osteoarthritis Initiative (OAI) pilot study database. As per OAI protocol, these subjects underwent 3T MRI at baseline and every twelve months thereafter, including a 3D DESS WE sequence. We analyzed the baseline and twenty-four month images. Each subject was scanned twice at these visits, thus generating scan-rescan information. Images were segmented with an automated multi-atlas framework platform and then 3D renderings of the bone structure were created from the segmentations. Curvature maps were extracted from the 3D renderings and morphed into a reference atlas to determine precision, to generate population statistics, and to visualize cross-sectional and longitudinal curvature changes.

RESULTS

The baseline scan-rescan root mean square error values ranged from 0.006mm(-1) to 0.013mm(-1), and from 0.007mm(-1) to 0.018mm(-1) for the SCB of the femur and the tibia, respectively. The standardized response of the mean of the longitudinal changes in curvature in these regions ranged from -0.09 to 0.02 and from -0.016 to 0.015, respectively.

CONCLUSION

The fully automated system produces accurate and precise curvature maps of femoral and tibial SCB, and will provide a valuable tool for the analysis of the curvature changes of articulating bone surfaces during the course of knee OA.

OARSI Clinical Trials Recommendations: Knee imaging in clinical trials in osteoarthritis

Significant advances have occurred in our understanding of the pathogenesis of knee osteoarthritis (OA) and some recent trials have demonstrated the potential for modification of the disease course. The purpose of this expert opinion, consensus driven exercise is to provide detail on how one might use and apply knee imaging in knee OA trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, sequences artifacts); quality assurance (QA)/control procedures; measurement methods; measurement performance (reliability, responsiveness, validity); recommendations for trials; and research recommendations.

Local area cartilage segmentation: a semiautomated novel method of measuring cartilage loss in knee osteoarthritis

OBJECTIVE

To assess the responsiveness and reader time of a novel semiautomated tool to detect knee cartilage loss over 2 years in subjects with knee osteoarthritis.

METHODS

A total of 122 subjects from the Osteoarthritis Initiative progression cohort were selected. A reader used the software method to segment cartilage on double-echo steady-state sequence scans in the medial compartment of the femur from the baseline and 24-month visits. Change in cartilage volume (ΔV) was measured at a fixed weight-bearing (WB) location with respect to the 3-dimensional coordinate system based on cylindrical coordinates. Change was measured for 5 regions of varying WB surface area centered on the fixed point. The average change (ΔV), the SD of ΔV, and the standardized response mean (SRM) are reported.

RESULTS

The SRM was −0.52 for the largest region and decreased in magnitude as smaller regions of cartilage were probed. The average evaluation time was <20 minutes per knee compartment, split approximately evenly between a technician and a trained reader.

CONCLUSION

The results establish that measurement of cartilage loss in a local region can be done efficiently and that the resultant measures are responsive to loss of cartilage over time. The coordinate system can potentially be used to objectively examine and establish a consistent location for all knees that is most responsive to change in cartilage volume. This technique can provide rapidly an objective quantitative measure of cartilage loss and could substantially reduce study costs for large trials and data sets.

Anatomical distribution of areas of preserved cartilage in advanced femorotibial osteoarthritis using CT arthrography (Part 1)

OBJECTIVE

To determine subregions of normal and abnormal cartilage in advanced stages of femorotibial osteoarthritis (OA) by mapping the entire femorotibial joint in a cohort of pre-total knee replacement (TKR) OA knees.

DESIGN

We defined an areal subdivision of the femorotibial articular cartilage surface on CT arthrography (CTA), allowing the division of the femorotibial articular surface into multiple (up to n = 204 per knee) subregions and the comparison of the same areas between different knees. Two readers independently classified each cartilage area as normal, abnormal or non-assessable in 41 consecutive pre-TKR OA knees.

RESULTS

A total of 6447 cartilage areas (from 41 knees) were considered assessable by both readers. The average proportion of preserved cartilage was lower in the medial femorotibial joint than in the lateral femorotibial joint for both readers (32.0/69.8% and 33.9/68.5% (medial/lateral) for reader 1 and 2 respectively, all P < 0.001). High frequencies of normal cartilage were observed at the posterior aspect of the medial condyle (up to 89%), and the anterior aspect of the lateral femorotibial compartment (up to 100%). The posterior aspect of the medial condyle was the area that most frequently exhibited preserved cartilage in the medial femorotibial joint, contrasting with the high frequency of cartilage lesions in the rest of that compartment.

CONCLUSIONS

Cartilage at the posterior aspect of the medial condyle, and at the anterior aspect of the lateral femorotibial compartment, may be frequently preserved in advanced grades of OA.

Responsiveness of Magnetic Resonance Imaging-derived Measures Over 2.7 Years

Objective.

To compare the responsiveness of magnetic resonance imaging (MRI)-derived measures of knee osteoarthritis over 2.7 years.

Methods.

There were 430 community-based participants (mean age 63.0 yrs, range 51–79 yrs; 51% female) measured at baseline and 2.7 years later. MRI of the right knee at both timepoints was performed to assess cartilage volume, cartilage defects, bone marrow lesions (BML), meniscal pathology, and tibial bone area. Global measurements were calculated as the sum of tibial and femoral measures. Standardized response mean (SRM) was calculated as the mean of change divided by the SD of change.

Results.

Global tibiofemoral cartilage volume and cartilage defects had the best SRM of −0.80 and 0.62, respectively. Site-specific measurements were lower (SRM range for cartilage volume −0.48 to −0.54 and cartilage defects 0.33 to 0.49). The SRM for BML was 0.12, meniscal pathology 0.39, and tibial bone area −0.09. Cartilage volume and/or defects tended to be more responsive in those with knee pain, those who were obese, those who were older, and those with radiographic osteoarthritis.

Conclusion.

Global cartilage volume demonstrated the best sensitivity to change, suggesting that if we relied solely on SRM to optimize clinical trial design, then cartilage volume would be the best outcome measure. However, clinical trials have shown that cartilage volume may be less responsive to treatment compared to other measures that have lower SRM (such as BML). Therefore, although one can optimize trial efficiency by finding more responsive endpoints, both sensitivity to change and magnitude of benefit should be considered.

Imaging research results from the osteoarthritis initiative (OAI): a review and lessons learned 10 years after start of enrolment

The Osteoarthritis Initiative (OAI) is a multicentre, prospective, observational, cohort study of knee osteoarthritis (OA) that began recruitment in 2004. The OAI provides public access to clinical and image data, enabling researchers to examine risk factors/predictors and the natural history of knee OA incidence and progression, and the qualification of imaging and other biomarkers. In this narrative review, we report imaging findings and lessons learned 10 years after enrolment has started. A literature search for full text articles published from the OAI was performed up to 31 December 2013 using Pubmed and the OAI web page. We summarise the rationale, design and imaging protocol of the OAI, and the history of OAI publications. We review studies from early partial, and later full OAI public data releases. The latter are structured by imaging method and tissue, reviewing radiography and then MRI findings on cartilage morphology, cartilage lesions and composition (T2), bone, meniscus, muscle and adipose tissue. Finally, analyses directly comparing findings from MRI and radiography are summarised. Ten years after the first participants were enrolled and first papers published, the OAI has become an invaluable resource to the OA research community. It has fuelled novel methodological approaches of analysing images, and has provided a wealth of information on OA pathophysiology. Continued collection and public release of long-term observations will help imaging measures to gain scientific and regulatory acceptance as 'prognostic' or 'efficacy of intervention' biomarkers, potentially enabling shorter and more efficient clinical trials that can test structure-modifying therapeutic interventions (NCT00080171).

Structural correlates of pain in joints with osteoarthritis

OBJECTIVE

To describe the insights on the epidemiology of pain-structure association and the ramifications of these studies for clinical trials.

DESIGN

Narrative review summarizing the pertinent literature in this area, summarizing some of the methodologic challenges inherent and proposing some research initiatives to further understanding of this complex science.

RESULTS

The predominant symptom in most patients presenting with osteoarthritis (OA) is pain. Over recent years a number of imaging based studies have narrowed the discord between structural findings on imaging and symptoms. The interpretation of pain in OA is still enigmatic and difficult to deal with both for clinicians and scientists.

CONCLUSIONS

We would envisage that over the next few years many of the pressing questions pertaining to research into the structure pain relationship will continue to be addressed. With this, we can expect clinically appropriate therapeutic advance.

Relationship between knee pain and the presence, location, size and phenotype of femorotibial denuded areas of subchondral bone as visualized by MRI

OBJECTIVE

Conflicting associations between imaging biomarkers and pain in knee osteoarthritis (OA) have been reported. A relation between pain and denuded areas of subchondral bone (dABs) has been suggested and this study explores this relationship further by relating the presence, phenotype, location and size of dABs to different measures of knee pain.

METHODS

633 right knees from the Osteoarthritis Initiative (OAI) (250 men, age 61.7 ± 9.6 yrs, BMI 29.4 ± 4.7 kg/m(2)) were included. Manual segmentation of the femorotibial cartilage plates was performed on 3 T coronal fast low angle shot with water excitation (FLASHwe) images. dABs were defined as areas where the subchondral bone was uncovered by cartilage. The following measures of pain were used: weightbearing-, non-weightbearing-, moderate-to-severe-, infrequent- and frequent knee pain.

RESULTS

Using pain measures from subjects without dABs as a reference, those with at least one dAB had a 1.64-fold higher prevalence ratio [PR, 95% confidence interval (CI) 1.24-2.18] to have frequent and 1.45-fold higher for moderate-to-severe knee pain (95% CI 1.13-1.85). Subjects with dABs in central subregions had a 1.53-fold increased prevalence of having weightbearing pain (95% CI 1.20-1.97), especially when the central subregion was moderately (>10%) denuded (PR 1.81, 95% CI 1.35-2.42). Individuals with cartilage-loss-type dABs had a slightly higher prevalence (PR 1.13, 95% CI 1.00-1.27) of having frequent knee pain compared to individuals with intra-chondral-osteophyte-type dABs.

CONCLUSION

This study supports a positive relation between femorotibial dABs and knee pain, especially when the dABs are located centrally (i.e., in weightbearing regions) or when the respective central subregion is moderately denuded.

Association between disease-specific quality of life and magnetic resonance imaging outcomes in a clinical trial of prolotherapy for knee osteoarthritis

OBJECTIVE

To assess the relation between knee osteoarthritis (KOA)-specific quality of life (QOL) and intra-articular cartilage volume (CV) in participants treated with prolotherapy. KOA is characterized by CV loss and multifactorial pain. Prolotherapy is an injection therapy reported to improve KOA-related QOL to a greater extent than blinded saline injections and at-home exercise, but its mechanism of action is unclear.

DESIGN

Two-arm (prolotherapy, control), partially blinded, controlled trial.

SETTING

Outpatient.

PARTICIPANTS

Adults with ≥3 months of symptomatic KOA (N=37).

INTERVENTIONS

Prolotherapy: 5 monthly injection sessions;

CONTROL

blinded saline injections or at-home exercise.

MAIN OUTCOME MEASURES

Primary: KOA-specific QOL scores (baseline, 5, 9, 12, 26, and 52wk; Western Ontario and McMaster University Osteoarthritis Index). Secondary: KOA-specific pain, stiffness, function (Western Ontario McMaster University Osteoarthritis Index subscales), and magnetic resonance imaging-assessed CV (baseline, 52wk).

RESULTS

Knee-specific QOL improvement among prolotherapy participants exceeded that among controls (17.6±3.2 points vs 8.6±5.0 points; P=.05) at 52 weeks. Both groups lost CV over time (P<.05); no between-group differences were noted (P=.98). While prolotherapy participants lost CV at varying rates, those who lost the least CV ("stable CV") had the greatest improvement in pain scores. Among prolotherapy participants, but not control participants, the change in CV and the change in pain (but not stiffness or function) scores were correlated; each 1% CV loss was associated with 2.7% less improvement in pain score (P<.05).

CONCLUSIONS

Prolotherapy resulted in safe, substantial improvement in KOA-specific QOL compared with control over 52 weeks. Among prolotherapy participants, but not controls, magnetic resonance imaging-assessed CV change (CV stability) predicted pain severity score change, suggesting that prolotherapy may have a pain-specific disease-modifying effect. Further research is warranted.

Responsiveness of quantitative cartilage measures over one year in knee osteoarthritis: comparison of radiography and MRI assessments

PURPOSE

To directly compare the responsiveness of quantitative imaging measures of disease progression in knee osteoarthritis (OA). In the medial compartment of the knee comparison was made between: 1) radiographic joint space narrowing (JSN); 2) global quantitative magnetic resonance imaging (qMRI) of cartilage volume; 3) regional qMRI of cartilage thickness; and 4) regional analysis using an ordered value (OV) methodology.

MATERIALS AND METHODS

3T MRI and weight-bearing radiography of the knees were performed at baseline and 1-year timepoints in 23 subjects (mean age 63 years) with symptomatic knee OA. Standardized response means (SRM) were calculated for each measure. Statistical analysis to determine significance of change between timepoints was performed with a two-tailed Student's t-test (JSN, global, regional analysis) and nonparametric Mann-Whitney test (ordered values).

RESULTS

At 1 year, global cartilage volume losses of 2.3% (SRM -0.44) in the medial tibia and 6.9% in the medial femur (SRM -0.74) were recorded. SRM for JSN was -0.46. Regional analysis revealed largest reductions in cartilage thickness in the external (SRM -0.84) weight-bearing subregion of the medial femur and in the posterior subregion of the medial tibia (SRM -0.79). OV analysis in the medial compartment revealed areas of cartilage thinning (four ranked OV) and cartilage thickening (two ranked OV).

CONCLUSION

The MRI OV approach proved to be a superior analysis tool for detecting changes in cartilage morphology over a 1-year period. Radiographically defined JSN was found to be the least responsive measurement method of knee OA disease progression.

Osteoarthritis

The pathogenesis of osteoarthritis (OA) appears to be the result of a complex interplay between mechanical, cellular and biochemical forces. Obesity is the strongest risk factor for disease onset in the knee, and mechanical factors dominate the risk for disease progression. OA is a highly prevalent and disabling disease. The current pre-eminent focus in OA research and clinical practice is on persons with established radiographic symptomatic disease. This is the very end-stage of disease genesis, and modern therapies hence are largely palliative. In an effort to mitigate the rising tide of increasing OA prevalence and disease impact, we need to focus more on preventing the onset of disease and modifying the structural progression of OA. Greater therapeutic attention to the important role of mechanical factors, joint injury and obesity in OA etiopathogenesis, is required if we are to find ways of reducing the public health impact of this condition.

Direct comparison of fixed flexion, radiography and MRI in knee osteoarthritis: responsiveness data from the Osteoarthritis Initiative

OBJECTIVE

Minimum radiographic joint space width (mJSW) represents the Food and Drug Administration (FDA) standard for demonstrating structural therapeutic benefits for knee osteoarthritis (KOA), but only shows moderate responsiveness (sensitivity to change). We directly compare the responsiveness of magnetic resonance imaging (MRI)-based cartilage thickness and JSW measures from fixed-flexion radiography (FFR) and explore the correlation of region-matched changes between both methods.

METHODS

Nine hundred and sixty-seven knees of Osteoarthritis Initiative participants with radiographic KOA were studied: 445 over 1 year with coronal FLASH MRI and FFR, and 375/522 over 1/2 years with sagittal DESS MRI and FFR. Standardized response means (SRM) of cartilage thickness and mJSW were compared using the sign-test.

RESULTS

With FLASH MRI, SRM was -0.28 for medial femorotibial compartment (MFTC) cartilage loss vs -0.15 for mJSW, and -0.32 vs -0.22 for the most sensitive MRI subregion (central MFTC) vs the most sensitive fixed-location JSW(x = 0.25). With DESS MRI, 1-year SRM was -0.34 for MFTC vs -0.22 for mJSW and -0.44 vs -0.28 for central MFTC vs JSW(x = 0.225). Over 2 years, the SRM was significantly greater for MFTC than for mJSW (-0.43 vs -0.31, P = 0.017) and for central MFTC than for JSW(x = 0.225) (-0.51 vs -0.44, P < 0.001). Correlations between changes in spatially matched MRI subregions and fixed-location JSW were not consistently higher (r = 0.10-0.51) than those between non-matched locations (r = 0.15-0.50).

CONCLUSIONS

MRI displays greater responsiveness in KOA than JSW FFR-based JSW, with the greatest SRM observed in the central medial femorotibial compartment. Fixed-location radiographic measures appear not capable of determining the spatial distribution of femorotibial cartilage loss.

The Osteoarthritis Initiative (OAI) magnetic resonance imaging quality assurance update

OBJECTIVE

Longitudinal quantitative evaluation of cartilage disease requires reproducible measurements over time. We report 8 years of quality assurance (QA) metrics for quantitative magnetic resonance (MR) knee analyses from the Osteoarthritis Initiative (OAI) and show the impact of MR system, phantom, and acquisition protocol changes.

METHOD

Key 3T MR QA metrics, including signal-to-noise, signal uniformity, T2 relaxation times, and geometric distortion, were quantified monthly on two different phantoms using an automated program.

RESULTS

Over 8 years, phantom measurements showed root-mean-square coefficient-of-variation reproducibility of <0.25% (190.0 mm diameter) and <0.20% (148.0 mm length), resulting in spherical volume reproducibility of <0.35%. T2 relaxation time reproducibility varied from 1.5% to 5.3%; seasonal fluctuations were observed at two sites. All other QA goals were met except: slice thicknesses were consistently larger than nominal on turbo spin echo images; knee coil signal uniformity and signal level varied significantly over time.

CONCLUSIONS

The longitudinal variations for a spherical volume should have minimal impact on the accuracy and reproducibility of cartilage volume and thickness measurements as they are an order of magnitude smaller than reported for either unpaired or paired (repositioning and reanalysis) precision errors. This stability should enable direct comparison of baseline and follow-up images. Cross-comparison of the geometric results from all four OAI sites reveal that the MR systems do not statistically differ and enable results to be pooled. MR QA results identified similar technical issues as previously published. Geometric accuracy stability should have the greatest impact on quantitative analysis of longitudinal change in cartilage volume and thickness precision.

Recent advances in osteoarthritis imaging--the osteoarthritis initiative

Osteoarthritis (OA) is the most common joint disorder. The osteoarthritis initiative (OAI) is a multicentre, longitudinal, prospective observational cohort study of knee OA that aims to provide publicly accessible clinical datasets, images and biospecimens, to enable researchers to investigate factors that influence the onset and development of OA, and evaluate biomarkers that predict and track the course of the disease. In this Perspectives, we describe the rationale and design of the OAI and its cohort, discuss imaging protocols and summarize image analyses completed to date. We include descriptive analyses of publicly available longitudinal (2-year) data of changes in cartilage thickness in a core sample of 600 knees from 590 participants in the OAI progression subcohort. Furthermore, we describe published methodological and applied imaging research that has emerged from OAI pilot studies and OAI data releases, and how these studies might contribute to clinical development of biomarkers for assessing the efficacy of intervention trials.

Clinical significance of bone changes in osteoarthritis

Osteoarthritis (OA), the most common form of arthritis, is now understood to involve all joint tissues, with active anabolic and catabolic processes. Knee OA in particular is considered to be a largely mechanically-driven disease. As bone adapts to loads by remodeling to meet its mechanical demands, bone alterations likely play an important role in OA development. Subchondral bone changes in bone turnover, mineralization, and volume result in altered apparent and material density of bone that may adversely affect the joint's biomechanical environment. Subchondral bone alterations such as bone marrow lesions (BMLs) and subchondral bone attrition (SBA) both tend to occur more frequently in the more loaded knee compartments, and are associated with cartilage loss in the same region. Recently, MRI-based 3D bone shape has been shown to track concurrently with and predict OA onset.The contributions of structural abnormalities to the clinical manifestations of knee OA are becoming better understood as well. While a structure-symptom discordance in knee OA is thought to exist, such observations do not take into account all potential factors that can contribute to between-person differences in the pain experience. Using novel methodology, pain fluctuation has been associated with changes in BMLs, synovitis and effusion. SBA has also been associated with knee pain, but the relationship of osteophytes to pain has been conflicting.Understanding the pathophysiologic sequences and consequences of OA pathology will guide rational therapeutic targeting. Importantly, rational treatment targets require understanding what structures contribute to pain as pain is the reason patients seek medical care.

Equivalence and precision of knee cartilage morphometry between different segmentation teams, cartilage regions, and MR acquisitions

OBJECTIVE

To compare precision and evaluate equivalence of femorotibial cartilage volume (VC) and mean cartilage thickness over total area of bone (ThCtAB.Me) from independent segmentation teams using identical Magnetic Resonance (MR) images from three series: sagittal 3D Dual Echo in the Steady State (DESS), coronal multi-planar reformat (DESS-MPR) of DESS and coronal 3D Fast Low Angle SHot (FLASH).

DESIGN

Nineteen subjects underwent test-retest MR imaging at 3 T. Four teams segmented the cartilage using prospectively defined plate regions and rules. Mixed models analysis of the pooled data were used to evaluate the effect of acquisition, team and plate on precision and Pearson correlations and mixed models were used to evaluate equivalence.

RESULTS

Segmentation team differences dominated measurement variability in most cartilage regions for all image series. Precision of VC and ThCtAB.Me differed significantly by team and cartilage plate, but not between FLASH and DESS. Mean values of VC and ThCtAB.Me differed by team (P < 0.05) for DESS, FLASH and DESS-MPR. FLASH VC was 4-6% larger than DESS in the medial tibia and lateral central femur, and FLASH ThCtAB.Me was 5-6% larger in the medial tibia, but 4-8% smaller in the medial central femur. Correlations between DESS and FLASH for VC and ThCtAB.Me were high (r = 0.90-0.97), except for DESS vs FLASH medial central femur ThCtAB.Me (r = 0.81-0.83).

CONCLUSIONS

Cartilage morphology metrics from different image contrasts had similar precision, were generally equivalent, and may be combined for cross-sectional analyses if potential systematic offsets are accounted for. Data from different teams should not be pooled unless equivalence is demonstrated for cartilage metrics of interest.

Validity of clinical measures of frontal plane knee alignment: data from the Osteoarthritis Initiative

Clinicians frequently assess frontal plane knee alignment of patients suspected of having knee osteoarthritis. However, there is little data to indicate whether simple to obtain clinical measures frontal plane alignment indicate the actual bony alignment of the knee or the extent and type of knee osteoarthritis. The purpose of this study was to assess the validity of goniometric measures of frontal plan knee position as a simple clinical tool to assess lower limb alignment and tibiofemoral OA status. Data from the Osteoarthritis Initiative were used to assess concurrent and diagnostic validity of goniometric measures. Data from 142 persons with symptomatic knee OA were used to examine concurrent validity, based on comparison to whole limb radiographs. Diagnostic validity was examined using data from 1390 persons with symptomatic knee OA, based on comparison to tibiofemoral joint space narrowing obtained from standardized radiographs. Associations between goniometric measures and whole limb radiographs were moderate (r = 0.43 for right knee and r = 0.46 for left knee). Goniometric measurements explained approximately 20% of the variation in lower limb alignment as measured by whole limb radiography suggesting that simple clinical measures of lower limb alignment contain too much error for inferring actual lower limb alignment. Diagnostic validity indicated positive likelihood ratios of 3.3 or less for detecting isolated severe medial or lateral joint space narrowing and a high rate of misclassification. Simple clinical assessments of frontal plane lower limb alignment or tibiofemoral OA status, in isolation, contain substantial error and likely do not inform clinical practice.

Use magnetic resonance imaging to assess articular cartilage

Magnetic resonance imaging (MRI) enables a noninvasive, three-dimensional assessment of the entire joint, simultaneously allowing the direct visualization of articular cartilage. Thus, MRI has become the imaging modality of choice in both clinical and research settings of musculoskeletal diseases, particular for osteoarthritis (OA). Although radiography, the current gold standard for the assessment of OA, has had recent significant technical advances, radiographic methods have significant limitations when used to measure disease progression. MRI allows accurate and reliable assessment of articular cartilage which is sensitive to change, providing the opportunity to better examine and understand preclinical and very subtle early abnormalities in articular cartilage, prior to the onset of radiographic disease. MRI enables quantitative (cartilage volume and thickness) and semiquantitative assessment of articular cartilage morphology, and quantitative assessment of cartilage matrix composition. Cartilage volume and defects have demonstrated adequate validity, accuracy, reliability and sensitivity to change. They are correlated to radiographic changes and clinical outcomes such as pain and joint replacement. Measures of cartilage matrix composition show promise as they seem to relate to cartilage morphology and symptoms. MRI-derived cartilage measurements provide a useful tool for exploring the effect of modifiable factors on articular cartilage prior to clinical disease and identifying the potential preventive strategies. MRI represents a useful approach to monitoring the natural history of OA and evaluating the effect of therapeutic agents. MRI assessment of articular cartilage has tremendous potential for large-scale epidemiological studies of OA progression, and for clinical trials of treatment response to disease-modifying OA drugs.

Unsupervised segmentation and quantification of anatomical knee features: data from the Osteoarthritis Initiative

This paper presents a fully automated method for segmenting articular knee cartilage and bone from in vivo 3-D dual echo steady state images. The magnetic resonance imaging (MRI) datasets were obtained from the Osteoarthritis Initiative (OAI) pilot study and include longitudinal images from controls and subjects with knee osteoarthritis (OA) scanned twice at each visit (baseline, 24 month). Initially, human experts segmented six MRI series. Five of the six resultant sets served as reference atlases for a multiatlas segmentation algorithm. The methodology created precise knee segmentations that were used to extract articular cartilage volume, surface area, and thickness as well as subchondral bone plate curvature. Comparison to manual segmentation showed Dice similarity coefficient (DSC) of 0.88 and 0.84 for the femoral and tibial cartilage. In OA subjects, thickness measurements showed test-retest precision ranging from 0.014 mm (0.6%) at the femur to 0.038 mm (1.6%) at the femoral trochlea. In the same population, the curvature test-retest precision ranged from 0.0005 mm(-1) (3.6%) at the femur to 0.0026 mm(-1) (11.7%) at the medial tibia. Thickness longitudinal changes showed OA Pearson correlation coefficient of 0.94 for the femur. In conclusion, the fully automated segmentation methodology produces reproducible cartilage volume, thickness, and shape measurements valuable for the study of OA progression.

Different thresholds for detecting osteophytes and joint space narrowing exist between the site investigators and the centralized reader in a multicenter knee osteoarthritis study--data from the Osteoarthritis Initiative

OBJECTIVE

To evaluate how the reading of knee radiographs by site investigators differs from that by an expert musculoskeletal radiologist who trained and validated them in a multicenter knee osteoarthritis (OA) study.

MATERIALS AND METHODS

A subset of participants from the Osteoarthritis Initiative progression cohort was studied. Osteophytes and joint space narrowing (JSN) were evaluated using Kellgren-Lawrence (KL) and Osteoarthritis Research Society International (OARSI) grading. Radiographs were read by site investigators, who received training and validation of their competence by an expert musculoskeletal radiologist. Radiographs were re-read by this radiologist, who acted as a central reader. For KL and OARSI grading of osteophytes, discrepancies between two readings were adjudicated by another expert reader.

RESULTS

Radiographs from 96 subjects (49 women) and 192 knees (138 KL grade ≥ 2) were included. The site reading showed moderate agreement for KL grading overall (kappa = 0.52) and for KL ≥ 2 (i.e., radiographic diagnosis of "definite OA"; kappa = 0.41). For OARSI grading, the site reading showed substantial agreement for lateral and medial JSN (kappa = 0.65 and 0.71), but only fair agreement for osteophytes (kappa = 0.37). For KL grading, the adjudicator's reading showed substantial agreement with the centralized reading (kappa = 0.62), but only slight agreement with the site reading (kappa = 0.10).

CONCLUSION

Site investigators over-graded osteophytes compared to the central reader and the adjudicator. Different thresholds for scoring of JSN exist even between experts. Our results suggest that research studies using radiographic grading of OA should use a centralized reader for all grading.

Weight loss in obese people has structure-modifying effects on medial but not on lateral knee articular cartilage

BACKGROUND

Obesity is an important risk factor for knee osteoarthritis (OA), Weight loss can reduce the symptoms of knee OA. No prospective studies assessing the impact of weight loss on knee cartilage structure and composition have been performed.

OBJECTIVES

To assess the impact of weight loss on knee cartilage thickness and composition.

METHODS

111 obese adults were recruited from either laparoscopic adjustable gastric banding or exercise and diet weight loss programmes from two tertiary centres. MRI was performed at baseline and 12-month follow-up to assess cartilage thickness. 78 eligible subjects also underwent delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), an estimate of proteoglycan content. The associations between cartilage outcomes (cartilage thickness and dGEMRIC index) and weight loss were adjusted for age, gender, body mass index (BMI) and presence of clinical knee OA.

RESULTS

Mean age was 51.7 ± 11.8 years and mean BMI was 36.6 ± 5.8 kg/m(2); 32% had clinical knee OA. Mean weight loss was 9.3 ± 11.9%. Percentage weight loss was negatively associated with cartilage thickness loss in the medial femoral compartment in multiple regression analysis (β=0.006, r(2)=0.19, p=0.029). This association was not detected in the lateral compartment (r(2)=0.12, p=0.745). Percentage weight loss was associated with an increase in medial dGEMRIC in multiple regression analysis (β=3.9, r(2)=0.26; p=0.008) but not the lateral compartment (r(2)=0.14, p=0.34). For every 10% weight loss there was a gain in the medial dGEMRIC index of 39 ms (r(2)=0.28; p=0.014). The lowest weight loss cut-off associated with reduced medial femoral cartilage thickness loss and improved medial dGEMRIC index was 7%.

CONCLUSIONS

Weight loss is associated with improvements in the quality (increased proteoglycan content) and quantity (reduced cartilage thickness losses) of medial articular cartilage. This was not observed in the lateral compartment. This could ultimately lead to a reduced need for total joint replacements and is thus a finding with important public health implications.

Simultaneous estimation of T(2) and apparent diffusion coefficient in human articular cartilage in vivo with a modified three-dimensional double echo steady state (DESS) sequence at 3 T

T(2) mapping and diffusion-weighted imaging complement morphological imaging for assessing cartilage disease and injury. The double echo steady state sequence has been used for morphological imaging and generates two echoes with markedly different T(2) and diffusion weighting. Modifying the spoiler gradient area and flip angle of the double echo steady state sequence allows greater control of the diffusion weighting of both echoes. Data from two acquisitions with different spoiler gradient areas and flip angles are used to simultaneously estimate the T(2) and apparent diffusion coefficient of each voxel. This method is verified in phantoms and validated in vivo in the knee; estimates from different regions of interest in the phantoms and cartilage are compared to those obtained using standard spin-echo methods. The Pearson correlations were 0.984 for T(2) (∼2% relative difference between spin-echo and double echo steady state estimates) and 0.997 for apparent diffusion coefficient (˜1% relative difference between spin-echo and double echo steady state estimates) for the phantom study and 0.989 for T(2) and 0.987 for apparent diffusion coefficient in regions of interest in the human knee in vivo. High accuracy for simultaneous three-dimensional T(2) and apparent diffusion coefficient measurements are demonstrated, while also providing morphologic three-dimensional images without blurring or distortion in reasonable scan times.

Greater rates of cartilage loss in painful knees than in pain-free knees after adjustment for radiographic disease stage: data from the osteoarthritis initiative

OBJECTIVE

To investigate whether rates of cartilage loss differ in knees with frequent baseline pain versus those without pain, after adjustment for radiographic osteoarthritis (OA) stage.

METHODS

One knee in each of 718 Osteoarthritis Initiative participants was examined: 310 with calculated Kellgren/Lawrence (K/L) grade 2, 299 with calculated K/L grade 3, and 109 with calculated K/L grade 4. Twelve-month change in (subregional) cartilage thickness was assessed by magnetic resonance imaging. Change in cartilage thickness in the central subregion of the weight-bearing medial femoral condyle and ordered value 1 (OV1) were selected as primary end points. Frequent knee symptoms were defined as pain, aching, or stiffness on most days of at least 1 month during the previous year.

RESULTS

The mean 12-month rate of change in cartilage thickness in the central subregion of the medial femoral condyle was -12 μm (standardized response mean [SRM] -0.15) in knees without pain (n = 146), -27 μm (SRM -0.25) in those with infrequent pain (n = 255), and -54 μm (SRM -0.32) in those with frequent pain (n = 317). Rates differed significantly between frequently painful knees and pain-free knees after adjustment for age, sex, body mass index, and calculated K/L grade (P = 0.011, R(2) = 2.6%, partial R(2) for frequent pain = 1.4%). Similar results were found in stratified samples of calculated K/L grade 2/calculated K/L grade 3 knees, and in analyses restricted to knees with consistent pain frequency between baseline and followup. OV1 results showed similar trends but were not significant.

CONCLUSION

Knees with frequent pain display greater rates of medial cartilage loss longitudinally than knees without pain, with or without adjustment or stratification for radiographic disease stage. Enrollment of participants with frequent knee pain in clinical trials can increase the observed rate of structural progression (i.e., cartilage loss) and sensitivity to change.

Advances in imaging of osteoarthritis and cartilage

Osteoarthritis (OA) is the most frequent form of arthritis, with major implications for individual and public health care without effective treatment available. The field of joint imaging, and particularly magnetic resonance (MR) imaging, has evolved rapidly owing to technical advances and the application of these to the field of clinical research. Cartilage imaging certainly is at the forefront of these developments. In this review, the different aspects of OA imaging and cartilage assessment, with an emphasis on recent advances, will be presented. The current role of radiography, including advances in the technology for joint space width assessment, will be discussed. The development of various MR imaging techniques capable of facilitating assessment of cartilage morphology and the methods for evaluating the biochemical composition of cartilage will be presented. Advances in quantitative morphologic cartilage assessment and semiquantitative whole-organ assessment will be reviewed. Although MR imaging is the most important modality in imaging of OA and cartilage, others such as ultrasonography play a complementary role that will be discussed briefly.

Definition of osteoarthritis on MRI: results of a Delphi exercise

OBJECTIVE

Despite a growing body of Magnetic Resonance Imaging (MRI) literature in osteoarthritis (OA), there is little uniformity in its diagnostic application. We envisage in the first instance the definition requiring further validation and testing in the research setting before considering implementation/feasibility testing in the clinical setting. The objective of our research was to develop an MRI definition of structural OA.

METHODS

We undertook a multistage process consisting of a number of different steps. The intent was to develop testable definitions of OA (knee, hip and/or hand) on MRI. This was an evidence driven approach with results of a systematic review provided to the group prior to a Delphi exercise. Each participant of the steering group was allowed to submit independently up to five propositions related to key aspects in MRI diagnosis of knee OA. The steering group then participated in a Delphi exercise to reach consensus on which propositions we would recommend for a definition of structural OA on MRI. For each round of voting, ≥60% votes led to include and ≤20% votes led to exclude a proposition. After developing the proposition one of the definitions developed was tested for its validity against radiographic OA in an extant database.

RESULTS

For the systematic review we identified 25 studies which met all of our inclusion criteria and contained relevant diagnostic measure and performance data. At the completion of the Delphi voting exercise 11 propositions were accepted for definition of structural OA on MRI. We assessed the diagnostic performance of the tibiofemoral MRI definition against a radiographic reference standard. The diagnostic performance for individual features was: osteophyte C statistic=0.61, for cartilage loss C statistic=0.73, for bone marrow lesions C statistic=0.72 and for meniscus tear in any region C statistic=0.78. The overall composite model for these four features was a C statistic=0.59. We detected good specificity (1) but less optimal sensitivity (0.46) likely due to detection of disease earlier on MRI.

CONCLUSION

We have developed MRI definition of knee OA that requires further formal testing with regards their diagnostic performance (especially in datasets of persons with early disease), before they are more widely used. Our current analysis suggests that further testing should focus on comparisons other than the radiograph, that may capture later stage disease and thus nullify the potential for detecting early disease that MRI may afford. The propositions are not to detract from, nor to discourage the use of traditional means of diagnosing OA.

Change in cartilage thickness, posttraumatic bone marrow lesions, and joint fluid volumes after acute ACL disruption: a two-year prospective MRI study of sixty-one subjects

BACKGROUND

Little is known about early morphologic change occurring with an acute injury of the anterior cruciate ligament. Magnetic resonance imaging was used in this study to investigate the two-year change in cartilage thickness, bone marrow lesions, and joint fluid of knees with acute anterior cruciate ligament injury treated surgically or nonsurgically and to identify factors associated with these changes.

METHODS

Sixty-one subjects (sixteen women and forty-five men with a mean age of twenty-six years) with acute anterior cruciate ligament injury to a previously uninjured knee were examined with use of a 1.5-T magnetic resonance imaging scanner at baseline and at three, six, twelve, and twenty-four months after the injury. Thirty-four subjects received rehabilitation and early anterior cruciate ligament reconstruction (a median of 44.5 days after the injury), eleven subjects received rehabilitation and a delayed anterior cruciate ligament reconstruction (408 days), and sixteen received rehabilitation alone. Morphologic measures were obtained from computer-assisted segmentation of magnetic resonance images. Factors tested for association were age, sex, activity level, treatment, and osteochondral fracture at baseline.

RESULTS

After twenty-four months, significant cartilage thinning occurred in the trochlea of the femur (mean, -4.3%; standard response mean = 0.88), whereas significant cartilage thickening occurred in the central medial aspect of the femur (mean, +2.7%; standard response mean = 0.46). A younger age at the time of injury was a risk factor for thickening in the central medial aspect of femur, whereas older age at injury was a risk factor for thinning in the trochlea of the femur. Treatment of the torn anterior cruciate ligament was not related to these changes nor was activity level or an osteochondral fracture at baseline. Posttraumatic bone marrow lesions in the lateral aspect of the tibia resolved completely in fifty-four of fifty-eight knees (median, six months) and lesions in the lateral aspect of the femur resolved completely in forty-four of forty-seven knees (median, three months); however, thirty new bone marrow lesions developed in the lateral aspect of twenty-one knees over the two-year period. None of the factors were related to the development of bone marrow lesions.

CONCLUSIONS

Morphologic change as visualized on magnetic resonance imaging occurs in the knee over the first two years after acute anterior cruciate ligament injury as demonstrated by cartilage thickening (central medial aspect of the femur), cartilage thinning (trochlea of the femur), the resolution of posttraumatic bone marrow lesions in the lateral part of the knee, and the development of new bone marrow lesions laterally. Age and male sex were independent risk factors for change in cartilage morphology.