Knee meniscal extrusion in a largely non-osteoarthritic cohort: association with greater loss of cartilage volume

Proper Cartilage Status for Meniscal Allograft Transplantation Cannot Be Accurately Determined by Patient Symptoms

BACKGROUND

Candidates for meniscal allograft transplantation (MAT) often already have a significant cartilage lesion when they present with a symptomatic knee. However, the level of symptoms required for MAT to be performed is poorly defined, leading to difficulties in selecting patients and the potential for further cartilage loss.

PURPOSE

To evaluate if various clinical evaluation scores reflect the articular cartilage status of the lateral compartment preoperatively in symptomatic, lateral meniscus-deficient knees.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 113 consecutive patients who underwent lateral MAT were reviewed. All patients were preoperatively assessed by the most common patient-reported outcome measures (PROMs), including the visual analog scale (VAS) for pain, Lysholm knee scale, International Knee Documentation Committee (IKDC) subjective form, and Tegner activity scale. The maximum grade from the International Cartilage Repair Society (ICRS) scale on either femoral or tibial articular cartilage was used for a correlation analysis between PROMs and ICRS grades and a comparison of PROMs between patients with low-grade (ICRS grade ≤2) and high-grade (ICRS grade 3 or 4) cartilage degeneration.

RESULTS

More than half of the patients had high-grade cartilage degeneration, even though their mean VAS pain score was low (3.1 ± 1.3). There were no significant relationships between ICRS grades and PROMs, except for the IKDC subjective score, which was weakly associated with the ICRS grade (Spearman ρ test, 2-sided, ρ = -.200, P = .034). When comparing patients with low-grade versus high-grade cartilage degeneration, there were no differences in PROMs except for the Lysholm score (67.8 ± 14.7 vs 62.3 ± 13.9, respectively; P = .044). Notably, 37 of 58 patients (63.8%) with high-grade chondral lesions only felt pain during severe exertion.

CONCLUSION

Mild or tolerable symptoms did not necessarily mean that articular cartilage was well preserved in patients undergoing MAT. The study findings suggest a need for close observation and greater caution concerning possible chondral damage in the treatment of meniscus-deficient knees.

Cross-sectional and Longitudinal Associations between Knee Joint Effusion Synovitis and Knee Pain in Older Adults

OBJECTIVE

To describe the cross-sectional and longitudinal associations between knee regional effusion synovitis and knee pain in older adults.

METHODS

Data from a population-based random sample (n = 880, mean age 62 yrs, 50% women) were used. Baseline knee joint effusion synovitis was graded (0-3) using T2-weighted magnetic resonance imaging (MRI) in the suprapatellar pouch, central portion, posterior femoral recess, and subpopliteal recess. Effusion synovitis of the whole joint was defined as a score of ≥ 2 in any subregion. Other knee structural (including cartilage, bone marrow, and menisci) lesions were assessed by MRI at baseline. Knee pain was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire at baseline and 2.6 years later. Multivariable analyses were performed after adjustment for age, sex, body mass index, and other structural lesions.

RESULTS

The prevalence of effusion synovitis was 67%. Suprapatellar pouch effusion synovitis was significantly and independently associated with increased total and nonweight-bearing knee pain in both cross-sectional and longitudinal analyses (for an increase in total knee pain of ≥ 5, RR 1.26 per grade, 95% CI 1.04-1.52), and increased weight-bearing knee pain in longitudinal analysis only. Effusion synovitis in posterior femoral recess and central portion were independently associated with increases in nonweight-bearing pain (RR 1.63 per grade, 95% CI 1.32-2.01 and RR 1.29 per grade, 95% CI 1.01-1.65, respectively) in longitudinal analyses only.

CONCLUSION

Knee joint effusion synovitis has independent associations with knee pain in older adults. Suprapatellar pouch effusion synovitis is associated with nonweight-bearing and weight-bearing knee pain, while posterior femoral recess and central portion effusion synovitis are only associated with nonweight-bearing pain.

Wolff's law in action: a mechanism for early knee osteoarthritis

There is growing interest in the role of bone in knee osteoarthritis. Bone is a dynamic organ, tightly regulated by a multitude of homeostatic controls, including genetic and environmental factors. One such key environmental regulator of periarticular bone is mechanical stimulation, which, according to Wolff’s law, is a key determinant of bone properties. Wolff’s law theorizes that repetitive loading of bone will cause adaptive responses enabling the bone to better cope with these loads. Despite being an adaptive response of bone, the remodeling process may inadvertently trigger maladaptive responses in other articular structures. Accumulating evidence at the knee suggests that expanding articular bone surface area is driven by mechanical stimulation and is a strong predictor of articular cartilage loss. Similarly, fractal analysis of bone architecture provides further clues that bone adaptation may have untoward consequences for joint health. This review hypothesizes that adaptations of periarticular bone in response to mechanical stimulation cause maladaptive responses in other articular structures that mediate the development of knee osteoarthritis. A potential disease paradigm to account for such a hypothesis is also proposed, and novel therapeutic targets that may have a bone-modifying effect, and therefore potentially a disease-modifying effect, are also explored.

Diagnostic performance of 3D standing CT imaging for detection of knee osteoarthritis features

OBJECTIVE

To determine the diagnostic performance of standing computerized tomography (SCT) of the knee for osteophytes and subchondral cysts compared with fixed-flexion radiography, using MRI as the reference standard.

METHODS

Twenty participants were recruited from the Multicenter Osteoarthritis Study. Participants' knees were imaged with SCT while standing in a knee-positioning frame, and with postero-anterior fixed-flexion radiography and 1T MRI. Medial and lateral marginal osteophytes and subchondral cysts were scored on bilateral radiographs and coronal SCT images using the OARSI grading system and on coronal MRI using Whole Organ MRI Scoring. Imaging modalities were read separately with images in random order. Sensitivity, specificity and accuracy for the detection of lesions were calculated and differences between modalities were tested using McNemar's test.

RESULTS

Participants' mean age was 66.8 years, body mass index was 29.6 kg/m(2) and 50% were women. Of the 160 surfaces (medial and lateral femur and tibia for 40 knees), MRI revealed 84 osteophytes and 10 subchondral cysts. In comparison with osteophytes and subchondral cysts detected by MRI, SCT was significantly more sensitive (93 and 100%; p < 0.004) and accurate (95 and 99%; p < 0.001 for osteophytes) than plain radiographs (sensitivity 60 and 10% and accuracy 79 and 94%, respectively). For osteophytes, differences in sensitivity and accuracy were greatest at the medial femur (p = 0.002).

CONCLUSIONS

In comparison with MRI, SCT imaging was more sensitive and accurate for detection of osteophytes and subchondral cysts than conventional fixed-flexion radiography. Additional study is warranted to assess diagnostic performance of SCT measures of joint space width, progression of OA features and the patellofemoral joint.

Ultrasound assessment of medial meniscal extrusion: a validation study using MRI as reference standard

OBJECTIVE. The purpose of this article is to validate both semiquantitative and quantitative ultrasound assessment of medial meniscal extrusion using MRI assessment as the reference standard. SUBJECTS AND METHODS. Ninety-three consecutive patients with chronic knee pain referred for knee MRI were evaluated by ultrasound and MRI on the same day. Two musculoskeletal radiologists assessed meniscal extrusion on ultrasound and MRI separately and independently and graded it semiquantitatively as follows: 0 (< 2 mm), 1 (≥ 2 mm and < 4 mm), and 2 (≥ 4 mm). Agreement between the ultrasound and MRI evaluations was determined using weighted kappa statistics. Intraclass correlation coefficients were used to evaluate agreement using the absolute values of extrusion (quantitative assessment). We further evaluated the diagnostic performance of ultrasound for the detection of medial meniscal extrusion using MRI as the reference standard. RESULTS. For semiquantitative grading, agreement between ultrasound and MRI was moderate for reader 1 (κ = 0.57) and substantial for reader 2 (κ = 0.64). Substantial agreement was found for both readers (intraclass correlation coefficients, 0.73 and 0.70) when comparing quantitative assessment of meniscal extrusion between ultrasound and MRI. Ultrasound showed excellent sensitivity (95% and 96% for each reader) and good specificity (82% and 70% for each reader) in the detection of meniscal extrusion. CONCLUSION. Ultrasound assessment of meniscal extrusion is reliable and can be used for both quantitative and semiquantitative assessment, exhibiting excellent diagnostic performance for the detection of meniscal extrusion compared with MRI.

Patient-related risk factors for the extrusion of lateral meniscal allograft transplants

PURPOSE

The objective of this study was to identify the patient-related risk factors for lateral meniscal extrusion after lateral meniscal allograft transplantation (MAT) regarding demographic characteristics, alignment, and pre-existing arthrosis.

METHODS

Seventy-one patients who underwent arthroscopic lateral MAT with bone bridge fixation between 2008 and 2011 were assessed. Lateral meniscal subluxation was measured on mid-coronal sections of magnetic resonance images 1 year postoperatively. Subluxation of more than 3 mm was considered to be extrusion. Age, gender, body mass index, time from previous meniscectomy, mechanical axis deviation, Kellgren-Lawrence grade on preoperative radiographs, and intraoperative International Cartilage Repair Society grade were assessed as possible patient-related factors.

RESULTS

The mean lateral subluxation in the coronal plane was 2.6 ± 1.6 mm. Among our patients, 23 transplants (32.4%) showed extrusion. The intraoperative cartilage status of the femoral condyle and tibial plateau showed significant differences between the nonextruded (≤3 mm) and extruded (>3 mm) groups (P = .010 and P = .001, respectively). There were no differences in other factors between these 2 groups. Binary logistic regression analysis showed that tibial-side cartilage wear of International Cartilage Repair Society grade 3 or more was a significant risk factor for meniscal extrusion.

CONCLUSIONS

Lateral meniscal extrusion 1 year after lateral MAT is affected by the degree of intraoperative cartilage wear, most notably on the tibial side. Patient demographic characteristics, alignment, and radiographic arthritic changes did not differ between nonextruded and extruded MAT cases.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Familial effects on structural changes relevant to knee osteoarthritis: a prospective cohort study

OBJECTIVE

Genetic factors play an important role in the pathogenesis of knee osteoarthritis (OA), but which knee structural changes mediate this is unclear. This study aimed to describe the differences in knee structural changes over 8-10 years between offspring having at least one parent with total knee replacement (TKR) for severe primary knee OA and controls with no family history of knee OA.

DESIGN

115 offspring (mean age 45 years) with a family history of TKR for severe knee OA were compared with 104 (mean age 46 years) controls. T1 or T2-weighted fat saturated magnetic resonance imaging (MRI) was performed respectively to evaluate knee cartilage defects, bone marrow lesions (BMLs), meniscal extrusion and tears at baseline and 10 years. Multivariate logistic regression model was used to adjust for potential confounders.

RESULTS

Offspring had a greater increase in cartilage defect score (1.03 vs 0.52, P = 0.007) and meniscal extrusion score (0.28 vs 0.10, P = 0.027) over 10 years, and a greater increase in meniscal tear score (0.40 vs 0.10, P = 0.012) over 8 years in the medial but not the lateral tibiofemoral compartment. Changes in BMLs over 8-years were not different between the two groups. These associations were independent of potential confounders, and strengthened after further adjustment for each other.

CONCLUSION

With the exception of BMLs, offspring with a family history of knee OA have a greater risk of increases in multiple knee structural abnormalities in the medial tibiofemoral compartment suggesting pleiotropic familial effects.

Influence of meniscus shape in the cross sectional plane on the knee contact mechanics

We present a three dimensional finite element analysis of stress distribution and menisci deformation in the human knee joint. The study is based on the Open Knee model with the geometry of the lateral meniscus which shows some degenerative disorders. The nonlinear analysis of the knee joint under compressive axial load is performed. We present results for intact knee, knee with complete radial posterior meniscus root tear and knee with total meniscectomy of medial or lateral meniscus. We investigate how the meniscus shape in the cross sectional plane influences knee-joint mechanics by comparing the results for flat (degenerated) lateral and normal medial meniscus. Specifically, the deformation of the menisci in the coronal plane and the corresponding stress values in cartilages are studied. By analysing contact resultant force acting on the menisci in axial plane we have shown that restricted extrusion of the torn lateral meniscus can be attributed to small slope of its cross section in the coronal plane. Additionally, the change of the contact area and the resultant force acting on the menisci as the function of compressive load are investigated.

Imaging of non-osteochondral tissues in osteoarthritis

OBJECTIVE

The aim of this review is to describe imaging techniques for evaluation of non-osteochondral structures such as the synovium, menisci in the knee, labrum in the hip, ligaments and muscles and to review the literature from recent clinical and epidemiological studies of OA.

METHODS

This is a non-systematic narrative review of published literature on imaging of non-osteochondral tissues in OA. PubMed and MEDLINE search for articles published up to 2014, using the keywords osteoarthritis, synovitis, meniscus, labrum, ligaments, plica, muscles, magnetic resonance imaging (MRI), ultrasound, computed tomography (CT), scintigraphy, and positron emission tomography (PET).

RESULTS

Published literature showed imaging of non-osteochondral tissues in OA relies primarily on MRI and ultrasound. The use of semiquantitative and quantitative imaging biomarkers of non-osteochondral tissues in clinical and epidemiological OA studies is reported. We highlight studies that have compared both imaging methodologies directly, and those that have established a relationship between imaging biomarkers and clinical outcomes. We provide recommendations as to which imaging protocols should be used to assess disease-specific changes regarding synovium, meniscus in the knee, labrum in the hip, and ligaments, and highlight potential pitfalls in their usage.

CONCLUSION

MRI and ultrasound are currently the most useful imaging modalities for evaluation of non-osteochondral tissues in OA. MRI evaluation of any tissue needs to be performed using appropriate MR pulse sequences. Ultrasound may be particularly useful for evaluation of small joints of the hand. Nuclear medicine and CT play a limited role in imaging of non-osteochondral tissues in OA.

Malalignment: a possible target for prevention of incident knee osteoarthritis in overweight and obese women

OBJECTIVES

The present study aims to investigate the associations between malalignment and incident knee OA after 2.5 years in a high-risk group of 333 middle-aged overweight women (BMI ≥ 27 kg/m(2)) free of clinical and radiological knee OA at baseline.

METHODS

The primary outcome measure was the incidence of knee OA, defined as the incidence of radiographic knee OA (Kellgren and Lawrence grade ≥2), clinical knee OA (ACR criteria) or medial or lateral joint space narrowing (≥1.0 mm). Using generalized estimating equations, associations between valgus and varus alignment (compared with neutrally aligned knees) and the primary outcome measure and all its items separately were studied.

RESULTS

Neither varus- nor valgus-aligned knees had a significantly increased risk for incident knee OA according to the primary outcome measure. A significantly increased risk for the development of radiographic knee OA was found for varus-aligned knees [odds ratio (OR) 3.3, 95% CI 1.5, 7.3]. Valgus-aligned knees showed a borderline increased OR (2.8, 95% CI 1.0, 8.0) for the development of radiographic knee OA. No statistically significant effects were found for varus and valgus alignment on the incidence of clinical knee OA or medial or lateral joint space narrowing.

CONCLUSION

Since this study was performed in a true target population, current data suggest that malalignment might be a target for the prevention of radiographic knee OA in overweight and obese women.

Are root avulsions of the lateral meniscus associated with extrusion at the time of acute anterior cruciate ligament injury?: a case control study

BACKGROUND

Lateral meniscal avulsions left in situ at the time of anterior cruciate ligament (ACL) reconstruction do well subjectively. Limited published results measure meniscal extrusion of the lateral compartment in this setting.

PURPOSE

To determine whether an avulsion of the posterior root of the lateral meniscus is associated with meniscal extrusion on magnetic resonance imaging (MRI).

STUDY DESIGN

Cohort study (prevalence); Level of evidence, 2.

METHODS

A prospective database of surgically treated ACL tears from 2007 to 2012 was reviewed. Isolated ACL tears without a concomitant injury were identified along with ACL tears in combination with lateral meniscal tears of the posterior root (PRLMTs). Thirty-five patients had ACL tears and PRLMTs verified arthroscopically, of which 23 patients had preoperative MRI scans available for review. From the same database, 25 isolated ACL tears with no meniscal injury were randomly chosen for comparison. Plain radiographs were reviewed for degenerative joint disease using the Kellgren-Lawrence scale. A board-certified radiologist blinded to arthroscopic findings reviewed each MRI scan using midcoronal sections to measure extrusion of the lateral meniscus. The average extrusion was calculated for each group and compared using a Student t test.

RESULTS

In the 48 patients reviewed, 1 patient was excluded because of a complex lateral meniscal tear that could not be measured on MRI. The remaining 47 consisted of 22 with root tears and 25 with intact menisci. None of these patients were noted to have degenerative joint disease greater than Kellgren-Lawrence grade 1. All of the patients with PRLMTs were noted to have intact meniscofemoral ligaments at the time of arthroscopic surgery. In the patients with ACL tears and PRLMTs, the average extrusion was 0.8 mm, and in the ACL tear group with an intact meniscus, the average extrusion measured 0.5 mm. No significant difference in the amount of extrusion was observed (P = .22).

CONCLUSION

At the time of acute ACL injuries, PRLMTs do not appear to result in meniscal extrusion on MRI.

Cross-sectional and longitudinal associations between circulating leptin and knee cartilage thickness in older adults

Objective

To investigate cross-sectional and longitudinal associations between serum leptin levels and knee cartilage thickness in older adults.

Methods

A prospective cohort of 163 randomly selected subjects (mean 63 years, range 52–78, 46% women) was studied. Knee cartilage thickness at medial tibial, lateral tibial, femoral and patellar sites was determined using T1-weighted fat-suppressed MRI. Serum leptin levels were measured by radioimmunoassay. Radiographic osteoarthritis, body fat (%), trunk fat (%), weight and height were measured, and body mass index (BMI) was calculated.

Results

Cross-sectionally, serum levels of leptin were negatively associated with femoral (β: −0.013, 95% CI −0.022 to −0.003), medial tibial (β: −0.009, 95% CI −0.018 to −0.001), lateral tibial (β: −0.012, 95% CI −0.021 to −0.003) and patellar (β: −0.014, 95% CI −0.026 to −0.002) cartilage thickness after adjustment for covariates. Moreover, BMI, trunk fat and total body fat were negatively associated with cartilage thickness, and the significant associations disappeared after further adjustment for leptin. Longitudinally, both baseline leptin and change in leptin were associated with greater changes in medial tibial cartilage thickness (β: −0.004, 95% CI −0.007 to −0.001 and β: −0.009, 95% CI −0.018 to −0.001, respectively) in multivariable analyses.

Conclusions

Serum levels of leptin are independently and consistently associated with reduced cartilage thickness cross-sectionally and longitudinally. In addition, the associations between adiposity measures and cartilage thickness are mediated by leptin, suggesting leptin may play a key role in cartilage thinning.

Biomechanical consequences of a posterior root tear of the lateral meniscus: stabilizing effect of the meniscofemoral ligament

PURPOSE

The purpose of this study was to evaluate the effects of different types of lateral meniscus root tears in terms of tibiofemoral contact stress.

METHODS

Ten porcine knees each underwent five different testing conditions with the menisci intact, a simulated lateral posterior root tear with and without cutting the meniscofemoral ligament and with an artificial tear of the posterior root of the medial meniscus. Biomechanical testing was performed at 30° of flexion with an axial load of 100 N. A pressure sensor (st Sensor Type S2042, Novel, Munich) was used to measure the tibiofemoral contact area and the tibiofemoral contact pressure. Data were analyzed to assess the differences in contact area and tibiofemoral peak contact pressure among the five meniscal conditions.

RESULTS

There was no significant difference in mean contact pressure between the state with the menisci intact and an isolated posterior root tear of the lateral meniscus. In case of a root tear and a tear of the meniscofemoral ligament, the contact area decreased in comparison with the intact state of the menisci. After additional cutting of the meniscofemoral ligament, the tibiofemoral contact pressure was significantly higher in comparison with the intact state and the avulsion injury. In the medial compartment, joint compression forces were significantly increased in comparison with the intact state after cutting the posterior root of the medial meniscus (P < 0.05).

CONCLUSIONS

The consequence of a medial meniscus root tear is well known and was verified by this analysis. The results of the present study show that the biomechanical consequences of a lateral meniscus root tear depend on the state of the meniscofemoral ligament. An increase in tibiofemoral contact pressure is only to be expected in combined injuries of the meniscus root and the meniscofemoral ligaments.

CLINICAL RELEVANCE

Posterior lateral meniscus root tear might have a better prognosis in terms of the development of osteoarthritis when the meniscofemoral ligament is intact.

There is no relation between mild malalignment and meniscal extrusion in trauma emergency patients

OBJECTIVE

To evaluate whether an alteration of the lower limb axis is associated with meniscal extrusion.

MATERIALS AND METHODS

Ninety-four patients who had complained of knee pain with good knee function and had a knee magnetic resonance image (MRI) and a full-length X-ray taken of the lower limb were included in the study. Meniscal extrusion was measured in the coronal MRI. Subluxation of the meniscus was considered minor or physiological if ≤ 3 mm, and major if >3 mm. The extrusion as a percentage of meniscus size was also calculated. Knee alignment (varus, negative value; valgus, positive value) was correlated with the presence of minor and major extrusion.

RESULTS

There were varus knees in 61 cases (58.7%), with a mean measured deviation of -2.63°. Valgus knees were observed in 27 knees (26%) and had a mean deviation of 2.22°. The medial meniscus showed major extrusion in 18 cases (17.3%). It corresponded to 44.7% of the meniscus size. The lateral menisci showed no subluxation in most cases. There was no correlation between alignment and meniscal extrusion in this series, either for the medial meniscus (p = 0.760) or for the lateral meniscus (p = 0.381).

CONCLUSIONS

In patients complaining of knee pain with good knee function, there is no relationship between mild malalignment and the degree of meniscus extrusion.

Anterior-posterior stability of the knee by an MR image subtraction method

The purpose of our study was to test the hypothesis that when a shear force was applied posteriorly to the loaded knee in vivo, there would be no relative motion between the tibia and the medial femoral condyle. Siemens 7 Tesla high-resolution MRI machine was used to scan eight healthy male volunteers with the knee at 15° of flexion. Two scans were obtained: the first with a compressive force of 660 N along the tibial long axis and a second with the compressive force and a posterior shear force of 36 N applied to the tibia. Solid models were created of the femur, tibia, and menisci for both loading conditions. The tibial models were superimposed enabling the displacements of the femur and menisci to be determined, relative to a fixed tibia. On average, the lateral femoral condyle displaced anteriorly by 0.66 mm but the medial femoral condyle displaced posteriorly by 0.36 mm. This indicated an axial rotation with a center between the lateral and medial condyles, but closer to the medial. The menisci displaced with the femoral condyles, but there was no indication that the medial meniscus was contributing to the pivoting action. This study supported the concept of medial anterior-posterior stability under weight-bearing conditions, but with structures other than the medial meniscus providing the stability. This study has application to the treatment of knee injuries and to knee arthroplasty design.

Radiographic osteoarthritis and pain are independent predictors of knee cartilage loss: a prospective study

BACKGROUND

There is controversy about whether pain and radiographic osteoarthritis (ROA) predict subsequent cartilage loss. The aim of this study was to describe the relationship between ROA, pain and cartilage loss in the knee.

METHODS

We studied randomly selected subjects at baseline and approximately 2.9 years later (n= 399). The presence of ROA was assessed at baseline with a standing anteroposterior semiflexed radiograph scored using the Osteoarthritis Research Society International atlas for osteophytes (OP) and joint space narrowing (JSN). Pain was assessed by the Western Ontario McMaster Osteoarthritis Index. Subjects' medial and lateral tibial cartilage volumes were determined by magnetic resonance imaging at both time points.

RESULTS

In cross-sectional analysis, both medial and lateral tibial cartilage volumes were lower in those with ROA. Any medial ROA predicted medial tibial cartilage loss (3.2% (standard deviation (SD) 5.6) vs 1.9% (SD 5.3) per annum) while any lateral ROA predicted both medial (4.0% (SD 6.0) vs 2.2% (SD 5.3) per annum) and lateral (3.5% (SD 5.8) vs 1.6% (SD 4.2) per annum) tibial cartilage loss (all P < 0.05). In multivariate analysis, JSN and OP at both medial and lateral sites had independent dose-response associations with tibial cartilage loss at both sites. Pain was an independent predictor of lateral, but not medial, tibial cartilage loss after taking ROA into account.

CONCLUSIONS

Subjects with ROA (either JSN or OP) and, to a lesser extent, pain lose cartilage faster than subjects without ROA and the more severe the ROA the greater the rate of loss. These findings have implications for the design of clinical trials.

UTE-T2∗ mapping detects sub-clinical meniscus injury after anterior cruciate ligament tear

OBJECTIVE

Meniscus tear is a known risk factor for osteoarthritis (OA). Quantitative assessment of meniscus degeneration, prior to surface break-down, is important to identification of early disease potentially amenable to therapeutic interventions. This work examines the diagnostic potential of ultrashort echo time-enhanced T2∗ (UTE-T2∗) mapping to detect human meniscus degeneration in vitro and in vivo in subjects at risk of developing OA.

DESIGN

UTE-T2∗ maps of 16 human cadaver menisci were compared to histological evaluations of meniscal structural integrity and clinical magnetic resonance imaging (MRI) assessment by a musculoskeletal radiologist. In vivo UTE-T2∗ maps were compared in 10 asymptomatic subjects and 25 ACL-injured patients with and without concomitant meniscal tear.

RESULTS

In vitro, UTE-T2∗ values tended to be lower in histologically and clinically normal meniscus tissue and higher in torn or degenerate tissue. UTE-T2∗ map heterogeneity reflected collagen disorganization. In vivo, asymptomatic meniscus UTE-T2∗ values were repeatable within 9% (root-mean-square average coefficient of variation). Posteromedial meniscus UTE-T2∗ values in ACL-injured subjects with clinically diagnosed medial meniscus tear (n=10) were 87% higher than asymptomatics (n=10, P<0.001). Posteromedial menisci UTE-T2∗ values of ACL-injured subjects without concomitant medial meniscal tear (n=15) were 33% higher than asymptomatics (P=0.001). Posterolateral menisci UTE-T2∗ values also varied significantly with degree of joint pathology (P=0.001).

CONCLUSION

Significant elevations of UTE-T2∗ values in the menisci of ACL-injured subjects without clinical evidence of subsurface meniscal abnormality suggest that UTE-T2∗ mapping is sensitive to sub-clinical meniscus degeneration. Further study is needed to determine whether elevated subsurface meniscus UTE-T2∗ values predict progression of meniscal degeneration and development of OA.

Factors associated with meniscal extrusion in knees with or at risk for osteoarthritis: the Multicenter Osteoarthritis study

PURPOSE

To assess the associations of meniscal tears, knee mal-alignment, cartilage damage, knee effusion, and body mass index with meniscal extrusion.

MATERIALS AND METHODS

The Multicenter Osteoarthritis study is an observational study of individuals who have or are at risk for knee osteoarthritis (OA). The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all patients. All subjects with available baseline knee radiographs and magnetic resonance (MR) images were included. MR imaging assessment of meniscal morphologic characteristics, meniscal position, and cartilage morphologic characteristics with use of the Whole-Organ Magnetic Resonance Imaging Score system was performed by two musculoskeletal radiologists. Cross-sectional associations of severity of meniscal tears, knee malalignment, tibiofemoral cartilage damage, knee effusion, and body mass index with meniscal extrusion were assessed by using logistic regression, with multiadjustments when testing each predictor.

RESULTS

A total of 1527 subjects (2131 knees; 2116 medial and 2106 lateral menisci) were included. Medially, meniscal tears, varus malalignment, and cartilage damage were associated with meniscal extrusion, with odds ratios (ORs) of 6.3 (95% confidence interval [CI]: 5.0, 8.0), 1.3 (95% CI: 1.1, 1.7), and 1.8 (95% CI: 1.4, 2.2), respectively. Laterally, meniscal tears, valgus malalignment, and cartilage damage were associated with meniscal extrusion, with ORs of 10.3 (95% CI: 7.1, 14.9), 2.2 (95% CI: 1.5, 3.2), and 2.0 (95% CI: 1.3, 2.9), respectively.

CONCLUSION

Meniscal tears are not the only factors associated with meniscal extrusion; other factors include knee malalignment and cartilage damage. Meniscal extrusion is probably an effect of the complex interactions among joint tissues and mechanical stresses involved in the OA process.

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.

A clinical sign to detect root avulsions of the posterior horn of the medial meniscus

PURPOSE

The goal of the present report was to describe a new clinical sign to make a clinical diagnosis of meniscal extrusion related to medial meniscal root avulsion.

METHODS

Description of an easy clinical sign to detect extrusion of the medial meniscus at the anteromedial joint line. A varus stress test was applied in full extension before and after transosseous repair of an isolated traumatic avulsion of the posterior root of the medial meniscus in a 21-year-old patient. The clinical sign was verified by sectioning of the meniscotibial ligament during knee arthroplasty surgery in 3 patients.

RESULTS

With a deficient posterior root, the clinical sign was positive, showing anteromedial extrusion under varus stress. After repair and at clinical follow-up, extrusion was normalized.

CONCLUSION

Making the clinical diagnosis of medial meniscus extrusion after knee injury by applying a simple varus stress test to the knee and palpating the anteromedial meniscal extrusion might help physicians to suspect a medial meniscus root tear in the early stages after the injury as well as to evaluate its reduction after repair. A varus stress test in full extension should be performed systematically in patients where a root tear of the medial meniscus is suspected as well as after surgery to evaluate the success of the repair.

Physical activity and osteoarthritis of the knee: can MRI scans shed more light on this issue?

Physical activity has many health benefits; however, there has been concern that exercise may increase the risk of the development or progression of osteoarthritis (OA) of the knee. There is little doubt that injury increases the risk of OA, but the role of physical activity independent to injury is uncertain. Recently, magnetic resonance imaging has allowed an in-depth assessment of joints and relevant structural changes-this review covers the recent imaging data relevant to this area. In children and young adults, physical activity appears beneficial for knee cartilage, possibly even in structurally abnormal knees. In addition, there is consistent evidence showing aerobic and strengthening exercise improves OA symptoms later in life. However, there is limited evidence associating exercise with structural changes in later life and this lacks consistency, suggesting little or no effect. In the meantime, it appears safe to prescribe exercise in later life without major concern for structural deterioration, although caution is appropriate in those with bone marrow lesions until more information becomes available.

The role of biomechanics in the initiation and progression of OA of the knee

The knee is one of the most common joints affected by osteoarthritis (OA), frequently with clinical presentation by middle age or even earlier. Accumulating evidence supports that knee OA progression is often driven by biomechanical forces, and the pathological response of tissues to such forces leads to structural joint deterioration, knee symptoms and reduced function. Well-known biomechanical risk factors for progression include joint malalignment and meniscal tear. The high risk of OA after knee injury demonstrates the critical role of biomechanical factors also in incident disease in susceptible individuals. However, our knowledge of the contributing biomechanical mechanisms in the development of early disease and their order of significance is limited. Part of the problem is our current lack of understanding of early-stage OA, when it starts and how to define it.

The association of prevalent medial meniscal pathology with cartilage loss in the medial tibiofemoral compartment over a 2-year period

OBJECTIVE

To investigate the association of different types of magnetic resonance imaging (MRI)-detected medial meniscal pathology with subregional cartilage loss in the medial tibiofemoral compartment.

METHODS

A total of 152 women aged >or=40 years, with and without knee osteoarthritis (OA) were included in a longitudinal 24-month observational study. Spoiled gradient recalled acquisitions at steady state (SPGR) and T2-weighted fat-suppressed MRI sequences were acquired. Medial meniscal status of the anterior horn (AH), body, and posterior horn (PH) was graded at baseline: 0 (normal), 1 (intrasubstance meniscal signal changes), 2 (single tears), and 3 (complex tears/maceration). Cartilage segmentation was performed at baseline and 24-month follow-up in various tibiofemoral subregions using computation software. Multiple linear regression models were applied for the analysis with cartilage loss as the outcome. In a first model, the results were adjusted for age and body mass index (BMI). In a second model, the results were adjusted for age, BMI and medial meniscal extrusion.

RESULTS

After adjusting for age, BMI, and medial meniscal extrusion, cartilage loss in the total medial tibia (MT) (0.04 mm, P=0.04) and the external medial tibia (eMT) (0.068 mm, P=0.04) increased significantly for compartments with grade 3 lesions. Cartilage loss in the total central medial femoral condyle (cMF) (0.071 mm, P=0.03) also increased significantly for compartments with grade 2 lesions. Cartilage loss at the eMT was significantly related to tears of the PH (0.074 mm; P=0.03). Cartilage loss was not significantly increased for compartments with grade 1 lesions.

CONCLUSION

The protective function of the meniscus appears to be preserved in the presence of intrasubstance meniscal signal changes. Prevalent single tears and meniscal maceration were found to be associated with increased cartilage loss in the same compartment, especially at the PH.

Meniscal root tears: diagnosis and treatment

Meniscal tears within the body of the meniscus or at the meniscocapsular junction represent a well-understood and manageable condition encountered in clinical practice. In comparison, however, meniscal root tears (MRTs) often go unnoticed and represent a unique injury pattern with unique biomechanical consequences. Though first described decades ago, improvements in magnetic resonance imaging and arthroscopy have only recently enhanced our diagnostic and treatment capabilities with regard to MRTs. This review contains an anatomic description of the roots including their significance in meniscal function as well as the consequences of their loss. In addition, how to properly identify MRTs and when it is appropriate to surgically repair them are described. Finally, we review the surgical techniques available in the existing literature and present an illustrative case.

Local cytokine profiles in knee osteoarthritis: elevated synovial fluid interleukin-15 differentiates early from end-stage disease

OBJECTIVE

Much of what is known about the inflammatory response in the synovial membrane (SM) of patients with osteoarthritis (OA) comes from studies of synovial tissues from end-stage disease. In this study, we sought to better characterize the inflammatory infiltrate in symptomatic patients with early signs of knee OA, and to determine how inflammatory cell populations relate to the pattern of cytokine and degradative enzyme production.

METHODS

Study populations comprised patients with degenerative meniscal tears and early cartilage thinning undergoing arthroscopic procedures (early OA) and patients undergoing total knee replacement for end-stage OA. Quantitative real-time polymerase chain reaction (PCR) was used to measure expression of SM cytokines and enzymes implicated in the pathogenesis of inflammatory arthritis and OA, as well as cell lineage-specific markers. We quantified synovial fluid (SF) cytokines and enzymes by enzyme-linked immunosorbent assay (ELISA) and SM cell populations by immunohistochemistry.

RESULTS

We found increased levels of SF interleukin-15 (IL-15) protein in the early knee OA patients when compared to end-stage OA. Both SF IL-15 protein and numbers of CD8 cells within SM correlated with matrix metalloproteinase-1 (MMP-1) and three levels. TNF-alpha, IL-6 and IL-21 were also detectable in the SF of the majority of patients, and IL-15 levels were associated with IL-6 levels.

CONCLUSION

IL-15 is elevated in early knee OA, suggesting activation of an innate immune response in the SM. The association of IL-15 expression with CD8 transcripts and MMPs implicates this cytokine in OA pathogenesis and as a candidate therapeutic target.

Tibiofemoral joint osteoarthritis: risk factors for MR-depicted fast cartilage loss over a 30-month period in the multicenter osteoarthritis study

PURPOSE

To assess baseline factors that may predict fast tibiofemoral cartilage loss over a 30-month period.

MATERIALS AND METHODS

The Multicenter Osteoarthritis (MOST) study is a longitudinal study of individuals who have or who are at high risk for knee osteoarthritis. The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all participants. Magnetic resonance (MR) images were read according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) system. Only knees with minimal baseline cartilage damage (WORMS < or = 2.5) were included. Fast cartilage loss was defined as a WORMS of at least 5 (large full-thickness loss, less than 75% of the subregion) in any subregion at 30-month follow-up. The relationships of age, sex, body mass index (BMI), ethnicity, knee alignment, and several MR features (eg, bone marrow lesions, meniscal damage and extrusion, and synovitis or effusion) to the risk of fast cartilage loss were assessed by using a multivariable logistic regression model.

RESULTS

Of 347 knees, 90 (25.9%) exhibited cartilage loss, and only 20 (5.8%) showed fast cartilage loss. Strong predictors of fast cartilage loss were high BMI (adjusted odds ratio [OR], 1.11; 95% confidence interval [CI]: 1.01, 1.23), the presence of meniscal tears (adjusted OR, 3.19; 95% CI: 1.13, 9.03), meniscal extrusion (adjusted OR, 3.62; 95% CI: 1.34, 9.82), synovitis or effusion (adjusted OR, 3.36; 95% CI: 0.91, 12.4), and any high-grade MR-depicted feature (adjusted OR, 8.99; 95% CI: 3.23, 25.1).

CONCLUSION

In participants with minimal baseline cartilage damage, the presence of high BMI, meniscal damage, synovitis or effusion, or any severe baseline MR-depicted lesions was strongly associated with an increased risk of fast cartilage loss. Patients with these risk factors may be ideal subjects for preventative or treatment trials.

Imaging of knee osteoarthritis

New imaging modalities are broadening the possibilities in osteoarthritis (OA) research, and are offering new insights to help better understand the pathogenesis of this disease. Although knee radiographs are widely employed in epidemiological and clinical studies to assess structural pathology, joint radiographs provide limited outcome measures in knee OA, and other more valid, reliable and sensitive imaging modalities are now available. In particular, magnetic resonance imaging can directly visualize articular cartilage and other joint structures, such as bone and soft tissue, that are now recognized as part of the disease process. This chapter will examine imaging modalities in the assessment of knee OA, and the impact of these on our understanding of the pathogenesis of this disease.

The role of the meniscus in osteoarthritis genesis

The history of treating meniscal lesions has been characterized by firm belief in "radical" surgery, with serious long-term consequences for the individual and society. The menisci play a critical protective role for the knee joint through shock absorption and load distribution. Currently, the consensus in surgical treatment of meniscal tears is to preserve as much functional meniscal tissue as possible. Still, meniscal lesions are common, especially in the osteoarthritic knee. For health professionals, these lesions present a challenge in choosing the treatment that is best for the patient in both the short term and long term. A degenerative lesion, in the middle-aged or older patient, could suggest early-stage knee osteoarthritis and should be treated accordingly. Surgical resection of nonobstructive degenerate lesions may only remove evidence of the disorder while the osteoarthritis degradation proceeds. Well-designed randomized, controlled clinical trials are needed.

Two-year prospective longitudinal study exploring the factors associated with change in femoral cartilage volume in a cohort largely without knee radiographic osteoarthritis

OBJECTIVE

To identify factors associated with change in femoral cartilage volume over 2 years in a cohort largely without knee radiographic osteoarthritis.

METHODS

A total of 252 subjects (mean 45 years, range 28-60) were used for this study. T1-weighted fat saturation magnetic resonance imaging was performed at baseline and approximately 2 years later. Knee femoral condyle cartilage volume, femoral cartilage defect (0-4 scale) and tibial bone size were determined.

RESULTS

The total femoral cartilage volume loss was 6.3% for the 2.3-year period. Factors associated with this annual change were female gender (females vs males: -1.69%, P<0.01), age (over vs under 40 years: -0.96%, P=0.01), smoking (beta: -0.04% per pack-years, P<0.01), as well as lower limb muscle strength (r: +0.32, P<0.01) and its change (beta: +0.34% per quartile, P<0.05). Structural factors associated with change included baseline femoral cartilage volume (beta: -0.36% per ml, P<0.01), femoral cartilage defects (beta: +1.07% per grade, P<0.01), tibial bone area (beta: +0.13% per cm(2), P<0.05), lateral osteophytes (beta: -1.91% per grade, P<0.01) and change in femoral cartilage defects (beta: -0.8% per grade, P<0.001).

CONCLUSIONS

This study provides evidence confirming that significant risk factors are associated with femoral cartilage loss and these include gender (female), age, smoking, and severity of lower limb muscle weakness. It also supports the hypothesis that femoral cartilage swelling reflected by an increased baseline cartilage volume could be a predictor of disease progression. Our findings also provide interesting clues to implement preventive measures that can possibly prevent or reduce knee cartilage loss.

Do MRI features at baseline predict radiographic joint space narrowing in the medial compartment of the osteoarthritic knee 2 years later?

PURPOSE

The purpose of the study was to relate magnetic resonance imaging (MRI) features at baseline with radiographically determined joint space narrowing (JSN) in the medial compartment of the knee after 2 years in a group of patients with symptomatic osteoarthritis at multiple joint sites.

MATERIALS AND METHODS

MRI of the knee and standardized radiographs were obtained at baseline and after 2 years in 186 patients (81% female; aged 43-76 years; mean 60 years). MRI was analyzed for bone marrow lesions, cysts, osteophytes, hyaline cartilage defects, joint effusion, and meniscal pathology in the medial compartment. Radiographs were scored semiquantitatively for JSN in the medial tibiofemoral joint using the Osteoarthritis Research Society International (OARSI) atlas. Radiological progression was defined as > or =1 grade increase. Associations between baseline magnetic resonance (MR) parameters and subsequent radiographic JSN changes were assessed using logistic regression. Relative risk (RR) was then calculated.

RESULTS

Radiographic progression of JSN was observed in 17 (9.1%) of 186 patients. Eleven patients had a Kellgren and Lawrence (KL) score of > or =2. A significant association was observed between all patients and meniscal tears (RR 3.57; confidence interval (CI) 1.08-10.0) and meniscal subluxation (RR 2.73; CI 1.20-5.41), between KL < 2 and meniscal subluxation (RR 11.3; CI 2.49-29.49) and KL > or = 2 and meniscus tears (RR 8.91; CI 1.13-22.84) and radiographic JSN 2 years later. Follow-up MR in 15 of 17 patients with progressive JSN showed only new meniscal abnormalities and no progression of cartilage loss.

CONCLUSION

Meniscal pathology (tears and/or meniscal subluxation) was the only MRI parameter to be associated with subsequent radiographic progression of JSN in the medial tibiofemoral compartment on a radiograph 2 years later, as assessed by the OARSI score.