Radiographic vs. MRI vs. arthroscopic assessment and grading of knee osteoarthritis - are we using appropriate imaging?

Purpose Radiographs and MRI scans are commonly used imaging techniques in the assessment of knee osteoarthritis. However, it currently remains uncertain how good a representation of the actual condition of the knee joint these investigations provide. By comparing them against arthroscopic findings the aim of our study was to conclude how accurate these imaging techniques are at grading knee osteoarthritis. Methods This was a retrospective study looking at knee arthroscopies performed at a tertiary centre over a 5 year period. The Outerbridge grade given at arthroscopy was correlated with pre-operative radiograph and MRI scores, so as to assess the reliability of these imaging techniques at predicting the actual severity of knee osteoarthritis seen. Results Kellgren-Lawrence (KL) grading of radiographs was moderately correlated with Outerbridge grades from arthroscopy for the medial compartment of the knee (Spearman’s rho (SR) 0.483, p < 0.001), with a milder correlation in the lateral compartment (SR 0.218, p = 0.003). MRI reporting of knee osteoarthritis was moderately correlated with Outerbridge grades in the medial compartment (SR 0.451, p < 0.001), mildly correlated for both the lateral (SR 0.299, p < 0.001) and patellofemoral joint compartments (SR 0.142, p = 0.054). KL and MRI grading was moderately correlated for the medial compartment (SR 0.475, p < 0.001) and mildly correlated for the lateral compartment (SR 0.277, p < 0.001). Conclusion The ability of radiographs to represent the actual condition of knee osteoarthritis is underestimated. KL grading especially best represents the disease seen in the medial compartment of the knee joint, with a moderate correlation to Outerbridge scores given on arthroscopic assessment. We suggest that whilst MRI is a useful tool in the investigation of knee symptoms, it is often unnecessarily used in patients with OA, when in fact, radiographs alone would be sufficient. Evidence level III

Preoperative Nodal US Features for Predicting Recurrence in N1b Papillary Thyroid Carcinoma

This study aimed to investigate whether preoperative ultrasonographic (US) features of metastatic lymph nodes (LNs) are associated with tumor recurrence in patients with N1b papillary thyroid carcinoma (PTC). We enrolled 692 patients (mean age, 41.9 years; range, 6–80 years) who underwent total thyroidectomy and lateral compartment LN dissection between January 2009 and December 2015 and were followed-up for 12 months or longer. Clinicopathologic findings and US features of the index tumor and metastatic LNs in the lateral neck were reviewed. A Kaplan-Meier analysis and Cox proportion hazard model were used to analyze the recurrence-free survival rates and features associated with postoperative recurrence. Thirty-seven (5.3%) patients had developed recurrence at a median follow-up of 66.5 months. On multivariate Cox proportional hazard analysis, male sex (hazard ratio [HR], 2.277; 95% confidence interval [CI]: 1.131, 4.586; p = 0.021), age ≥55 years (HR, 3.216; 95% CI: 1.529, 6.766; p = 0.002), LN size (HR, 1.054; 95% CI: 1.024, 1.085; p < 0.001), and hyperechogenicity of LN (HR, 8.223; 95% CI: 1.689, 40.046; p = 0.009) on US were independently associated with recurrence. Preoperative US features of LNs, including size and hyperechogenicity, may be valuable for predicting recurrence in patients with N1b PTC.

ACL Reconstruction Combined With the Arnold-Coker Modification of the MacIntosh Lateral Extra-articular Tenodesis: Long-term Clinical and Radiological Outcomes

Background: Interest in the role of lateral extra-articular tenodesis (LET) in preventing rotatory instability and the pivot-shift phenomenon after anterior cruciate ligament reconstruction (ACLR) has been recently renewed. Nevertheless, there is still concern about overconstraint of the lateral compartment of the knee and the risk of subsequent osteoarthritis (OA). Purpose: The purpose of this retrospective study was to compare long-term subjective and objective outcomes and the rate of OA development between patients undergoing isolated ACLR (iACLR) with a hamstring tendon autograft and those with a combined Arnold-Coker modification of the McIntosh extra-articular procedure. Risk factors for long-term OA were evaluated. Study Design: Cohort study; Level of evidence, 3. Methods: The study included 165 consecutive patients treated at a single center by ACLR. A total of 86 patients underwent iACLR (iACLR group) and 79 received combined intra- and extra-articular reconstruction (ACLR+LET). The International Knee Documentation Committee (IKDC), Lysholm, and Tegner activity scores were administered. Knee stability was tested through the Lachman test, the pivot-shift test, and the KT-1000 knee arthrometer test. A positive pivot-shift test (++/+++), laxity on the KT-1000, and referred giving-way episodes or revision ACLR were considered failures. Radiographic results were assessed according to the Fairbank, IKDC, and Kellgren-Lawrence scales. Radiographic evaluation included both the overall tibiofemoral joint and the medial and lateral compartment separately. A univariate and a multivariate logistic regression with penalized maximum likelihood was used to identify risks factors associated with long-term OA. Results: The mean follow-up was 15.7 years. There were no statistically significant differences in subjective scores between the 2 groups. A side-to-side difference >5 mm on the KT-1000 arthrometer evaluation was found in 8 patients in the iACLR group and in 1 patient in the ACLR+LET group ( P = .01). Nine cases of failure were found in the iACLR group and only 1 case was found in the ACLR+LET group ( P = .0093). Patients in the iACLR group had a significantly higher OA grades than those in the ACLR+LET group for the overall tibiofemoral joint and the lateral compartment of the knee. No differences were found in the medial compartment. A higher level of lateral compartment OA was found in patients who received partial lateral meniscectomy in the iACLR group compared with those in the ACLR+LET group. Univariate and multivariate analysis results demonstrated that meniscectomy was the most significant factor for long-term OA development. Conclusion: A significantly higher risk of long-term OA was found with iACLR than with ACLR combined with the Arnold-Coker modification of the McIntosh extra-articular procedure. Knees with combined ACLR also had a significantly lower OA grade after partial lateral meniscectomy. Additionally, those undergoing combined ACLR had better knee stability and lower graft rupture rates at the long-term follow-up. Partial meniscectomy was the main risk factor negatively associated with OA changes.

Imaging of Noncontact Anterior Cruciate Ligament Injuries and Associated Bone Marrow Contusion Patterns

Anterior cruciate ligament (ACL) tears are commonly associated with bone contusions. Bone contusions can lend important insight into increased risk for more subtle concurrent injuries based on common injury mechanisms and patterns, as higher energy trauma has been tied to patterns of specific bone contusions and concomitant injuries. Lateral compartment contusions are most common and occur in pivot shift injuries. Medial compartment contusions may represent a contrecoup mechanism after the initial lateral injuries. Patellotibial contusions require axial loading but are also typically seen in conjunction with lateral and medial compartment contusions. The differences in ACL injury mechanics and physiology as shown by imaging contusion patterns can help clinicians better identify and treat the concurrent associated injuries.

Biomechanical Comparison of Kinematic and Mechanical Knee Alignment Techniques in a Computer Simulation Medial Pivot Total Knee Arthroplasty Model

Several concepts may be used to restore normal knee kinematics after total knee arthroplasty. One is a kinematically aligned (KA) technique, which restores the native joint line and limb alignment, and the other is the use of a medial pivot knee (MPK) design, with a ball and socket joint in the medial compartment. This study aimed to compare motions, contact forces, and contact stress between mechanically aligned (MA) and KA (medial tilt 3° [KA3] and 5° [KA5]) models in MPK. An MPK design was virtually implanted with MA, KA3, and KA5 in a validated musculoskeletal computer model of a healthy knee, and the simulation of motion and contact forces was implemented. Anteroposterior (AP) positions, mediolateral positions, external rotation angles of the femoral component relative to the tibial insert, and tibiofemoral contact forces were evaluated at different knee flexion angles. Contact stresses on the tibial insert were calculated using finite element analysis. The AP position at the medial compartment was consistent for all models. From 0° to 120°, the femoral component in KA models showed larger posterior movement at the lateral compartment (0.3, 6.8, and 17.7 mm in MA, KA3, and KA5 models, respectively) and larger external rotation (4.2°, 12.0°, and 16.8° in the MA, KA3, and KA5 models, respectively) relative to the tibial component. Concerning the mediolateral position of the femoral component, the KA5 model was positioned more medially. The contact forces at the lateral compartment of all models were larger than those at the medial compartment at >60° of knee flexion. The peak contact stresses on the tibiofemoral joint at 90° and 120° of knee flexion were higher in the KA models. However, the peak contact stresses of the KA models at every flexion angle were <20 MPa. The KA technique in MPK can successfully achieve near-normal knee kinematics; however, there may be a concern for higher contact stresses on the tibial insert.

Meniscal and Cartilage Changes on Serial MRI After Medial Opening-Wedge High Tibial Osteotomy

Background: Assessments of the effects of realignment using opening-wedge high tibial osteotomy (OWHTO) on the medial, lateral, and patellofemoral compartments have been limited to cartilage evaluations. Purpose/Hypothesis: The purpose was to evaluate the effects of OWHTO on the meniscus and cartilage of each compartment as a cooperative unit (meniscochondral unit) using serial magnetic resonance imaging (MRI). It was hypothesized that (1) favorable changes in the meniscochondral unit would occur in the medial compartment and (2) that changes in the patellofemoral and lateral compartments would be negligible. Study Design: Case series; Level of evidence, 4. Methods: Included were 36 knees that underwent OWHTO from March 2014 to February 2016 and had postoperative serial MRI. The MRI was performed at 19.9 ± 7.4 and 52.3 ± 8.3 months postoperatively, and the cartilage and meniscal changes were evaluated by highlighting the regions of interest. We evaluated the T2 relaxation times of each cartilage and meniscal area, the cross-sectional area of the menisci, and the extrusion of the medial meniscus (MM). The meniscochondral unit was assessed using subgroup analyses according to the status of the MM. Results: Significant decreases were seen in T2 relaxation times in the medial femoral condyle (MFC) ( P < .001) and medial tibial plateau (MTP) ( P = .050), and significant increases were seen in the lateral femoral condyle (LFC) ( P = .036). The change was more prominent in the MFC compared with the MTP and LFC ( P = .003). No significant changes were observed in the lateral tibial plateau, patella, or trochlear groove. The area of the lateral meniscus (body and posterior horn) was decreased compared with preoperative MRI ( P < .001 for both). The extent of MM extrusion decreased between the preoperative, first follow-up, and second follow-up MRIs ( P < .001). Conclusion: OWHTO affected the medial compartment positively, the lateral compartment negatively, and the patellofemoral compartment negligibly. The effects were more prominent and consistent in the medial than in the lateral compartment.

The Relationship Between Discoid Meniscus and Articular Cartilage Thickness: A Quantitative Observational Study With MRI

Background: Several cadaveric imaging studies have demonstrated that the articular cartilage thickness on the tibial plateau varies depending on coverage by native meniscal tissue. These differences are thought to partially contribute to the rates of cartilage degeneration and development of osteoarthritis after meniscectomy. Because there is greater tibial plateau coverage with meniscal tissue in the setting of a discoid meniscus, these findings may also have implications for the long-term health of the knee after saucerization of a torn discoid meniscus. Purpose: To evaluate the relationship between lateral compartment articular cartilage thickness and the presence or absence of a discoid meniscus. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Included in the study were 25 patients younger than 40 years of age who had undergone a 1.5-T or 3-T knee magnetic resonance imaging (MRI) between 2010 and 2016 at a single institution and had an intact, lateral discoid meniscus. Only patients with an otherwise asymptomatic lateral compartment were included. The authors then identified 35 age-matched controls with a nondiscoid, intact lateral meniscus who underwent knee MRI at the same institution and during the same period. The articular cartilage thicknesses in 6 zones of the lateral femoral condyle (LFC) and lateral tibial plateau (LTP) were measured for each patient by 2 musculoskeletal radiologists, and the mean thicknesses were compared between the study and control groups. Results: The average age at MRI was 22.63 years (range, 8.30-35.90 years) for the discoid group and 20.93 years (range, 8.43-34.99 years) for the nondiscoid group. The nondiscoid group had significantly greater mean articular cartilage thickness in all 6 zones of the LTP ( P < .05 for all). When comparing the zones of the LFC, there was no significant difference in the mean thickness in any zone between the 2 groups. Conclusion: Patients with discoid menisci had thinner baseline articular cartilage thickness in the LTP compared with those patients without discoid menisci.