Posterior Medial Femoral Condyle Research Articles

Large Osteophytes over 10 mm at Posterior Medial Femoral Condyle Can Lead to Asymmetric Extension Gap Following Bony Resection in Robotic Arm-Assisted Total Knee Arthroplasty with Pre-Resection Gap Balancing.

Robotic arm-assisted total knee arthroplasty (TKA) involves a pre-resection gap balancing technique to obtain the desired gap. However, the expected gap may change owing to the soft-tissue release effect of unreachable osteophytes. This study evaluated the effect of unreachable osteophytes of the posterior medial femoral condyle on gap changes following bony resection. We retrospectively analysed 129 robotic arm-assisted TKAs performed for varus knee osteoarthritis. Knees were classified according to the size of osteophytes on the posterior medial femoral condyle using preoperative computed tomography measurement. After the removal of reachable osteophytes, the robotic system measured pre- and post-resection medial extension (ME), lateral extension (LE), medial flexion (MF), and lateral flexion (LF) gaps. No extension gap changes were observed for 25 (19.4%), and no flexion gap changes were observed 41 (31.8%) knees, following bone cuts. ME, LE, MF, and LF gaps increased with the osteophyte size (p < 0.05). For osteophytes <10 mm, all the gaps increased symmetrically. However, for osteophytes >10 mm, the ME gap increased asymmetrically more than LE, MF, and LF gaps (p < 0.05). The gap changes due to bony resection were correlated to the osteophyte sizes of the posterior medial femoral condyle. Surgeons should plan a slightly tight medial extension gap to attain the desired gaps for >10 mm osteophytes.

Semimembranosus Tendon Findings in Acute Anterior Cruciate Ligament Tears: MRI Evaluation and Associated Lesions

Background: The semimembranosus (SM) tendon acts as a secondary dynamic stabilizer of the knee. It restrains external rotation and anterior translation of the medial compartment. Its role in the mechanism of injury during anterior cruciate ligament (ACL) rupture is unknown. Hypothesis: The bone bruise (BB) often detected at the posteromedial tibia in association with acute ACL tear may be related to the traction force from the SM tendon insertion. Magnetic resonance imaging (MRI) alterations can be detectable at the direct arm of the SM tendon in association with acute ACL injury. Study Design: Cross-sectional study: Level of evidence, 3. Methods: In the first study phase, 36 noninjured patients underwent knee MRI. The anatomic appearance of the SM tendon was evaluated. An imaging score for evaluating the SM tendon was developed for the purpose of the study. The intensity (in the axial or sagittal plane), morphology, and thickness of the distal SM tendon was evaluated and scored (4 total points). In the second study phase, 52 patients undergoing acute ACL reconstruction were included. Preoperative MRI was examined and scored, with documentation of BB at the posteromedial tibial plateau. Finally, arthroscopic diagnosis of a ramp lesion was confirmed. Logistic regression analysis was carried out for correlation between an altered MRI scoring system and the presence of BB at the posteromedial tibial plateau, the presence of a ramp lesion, or both. Results: Interrater agreement of 100% was obtained in the noninjured cohort (ie, no alteration found in any patient). The score validation in the cohort of patients with acute ACL injury showed a Cohen κ of 0.78 (interrater agreement, 82.7%). The direct arm of the SM tendon was altered in 35 of 52 patients (67.3%). A ramp lesion of the medial meniscus was arthroscopically detected in 21 patients (40.4%). The presence of BB at the posteromedial tibial plateau was detected in 33 patients (63.5%) and at the posterior medial femoral condyle in 1 (1.9%). Correlation analysis showed a significant association of a pathologic SM score with the presence of BB at the posteromedial tibial plateau (odds ratio = 2.7; P = .001). Conversely, no correlation was observed between the pathologic score and the presence of a ramp lesion (odds ratio = 0.88; P = .578). Conclusion: The prevalence of pathologic findings in the direct arm of the SM tendon insertion was high in the acutely injured cohort with ACL rupture and is correlated with the presence of BB at the posteromedial tibial plateau. The main hypothesis formulated for the study was confirmed.

The Clinical Outcomes of Measured Resection and Gap Balancing Techniques in Primary Total Knee Arthroplasty: A Meta-analysis.

At present, the clinical efficacy of measured resection (MR) and gap balancing (GB) techniques in total knee arthroplasty (TKA) is still controversial. The objective of this study was to evaluate the clinical outcome indexes of the two surgical methods through a meta-analysis. The literature was systematically searched on PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), WANFANG, Weipu (VIP), and China Biomedical Literature (CBM) electronic databases inception until June 12, 2022. RevMan 5.3 software (the Nordic Cochrane Center, the Cochrane Collaboration, Copenhagen, Denmark) was used to analyze all data of this study. The Cochrane risk bias assessment tool is a risk bias evaluation criterion recommended by the Cochrane Handbook for systematic reviews. Eleven studies involving 1268 knees in total were included. The main outcome indexes showed that the Knee Society Score (KSS) knee score (MD: -1.40; 95% CI: -2.57 to -0.22; p=0.02) and KSS knee function score (MD: -3.11; 95% CI: -3.72 to -2.50; p<0.001) in the GB group were higher 1 year after operation, while femoral component rotation angle (FCRA; MD: -0.75; 95% CI: -1.34 to -0.07; p=0.03) and the osteotomy volume of the posterior medial femoral condyle (MD: -0.76; 95% CI; -1.13 to -0.38; p<0.001) were greater in the GB group. In addition, there was no significant difference in the joint line change (MD: -0.03; 95% CI: -0.07 to 0.01; p=0.16) between the two groups. Secondary outcome results showed that the knee joint range of motion (ROM) in 3 months, and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score after 1 year were better in the GB group. However, the operation time of the MR group was shorter. In addition, this study revealed no significant differences in post-complications between these two groups. Although the GB technique may not provide better radiographic results or reduce the complication rate, the recovery of joint function showed earlier improvement.

Paper 15: Is Asymmetry of the Medial and Lateral Posterior Femoral Condyles Associated with ACL Rupture: A Case Control Study of Pediatric Patients

Objectives: Rates of anterior cruciate ligament (ACL) injury in the pediatric population have increased in the last 20 years. While many risk factors have been investigated, to the authors knowledge no study has analyzed the difference in the posterior femoral condyles in patients who have sustained ACL rupture. Therefore, this case control study sought to understand the relationship between the medial and lateral posterior condyles, as well as examining distal femoral version. The authors hypothesized that pediatric patients who suffered ACL rupture will have a relatively larger medial posterior femoral condyle leading to increase structural valgus in flexion. Methods: Pediatric patients with a pre-operative knee MRI who underwent ACL reconstruction between February 2016 and June 2020 at a tertiary orthopedic hospital were collected. Cases were matched to controls based on sex, laterality of injury, and age at imaging within 1.5 years. Medial and lateral posterior condylar height was measured for each participant. Condylar difference was calculated as medial posterior condylar height minus lateral posterior condylar height. The distal femoral version was calculated as the angle between the femoral posterior cortical axis and the posterior condylar axis. Mann-Whitney U tests were used to compare continuous variables. Significance was set as a p≤0.05. Results: A total of 72 participants were included in this analysis - 36 cases and 36 controls. Median age was 13.5 ± 3.3 years for all participants. Condylar difference was noted to be 1.8 mm greater in cases than controls (p=0.038), while distal femoral version was noted to be 2.0° greater in cases than controls (p=0.025). Conclusions: This study demonstrated a significantly greater posterior condylar height difference and distal femoral version among pediatric patients who suffered ACL rupture compared to a matched control group. We speculate that this morphology leads to a relative increase in knee valgus in flexion. [Figure: see text][Table: see text][Figure: see text]

How Does Anterior Cruciate Ligament Incompetence Influence the Varus Osteoarthritic Knee?

Introduction: The aims of our study were: (i) to assess the correlation of anterior cruciate ligament (ACL) deficiency with severity of preoperative varus deformity in osteoarthritic knees, (ii) to compare posterior medial femoral condyle (MFC) changes in ACL deficient vs ACL competent knees, and (iii) to compare the mean femoral external rotation of ACL deficient vs ACL competent knees. Methods: 250 consecutive ACL deficient and ACL competent patients each, undergoing total knee arthroplasty (TKA) for osteoarthritis with a varus deformity were reviewed retrospectively. Data from a prospectively collected computer navigation assisted TKA database was analyzed for an association between ACL insufficiency and: severity of the varus deformity, incidence of posterior MFC compensatory changes, and the magnitude of femoral component external rotation. Results: A statistically significant positive correlation was found between ACL incompetence and- (1) Severity of the knee varus deformity (p < 0.001), (2) Incidence of compensatory posterior MFC hypertrophy (p < 0.001) and (3) Femoral component external rotation required to balance the knee in flexion during TKA (p < 0.001). Conclusion: ACL deficiency is associated with an increase in the severity of the varus deformity. A significantly higher incidence of posterior MFC hypertrophy and increased values of the combined Whiteside-PCA angle are noted in ACL deficient knees compared with knees with an intact ACL. Multiple intraoperative landmarks must be assessed for setting femoral component rotation while performing TKA in the ACL deficient knee.

Accessory Lateral Head of the Right Gastrocnemius Muscle in a 65 year-old White Male Donor

The three muscles that form the calf muscle or triceps surae include the soleus muscle, the gastrocnemius muscle, and the plantaris muscle. Generally, the gastrocnemius muscle consists of a larger medial head and relatively smaller lateral head. It is responsible for plantar flexion of the foot. The lateral head arises from the posterior lateral femoral condyle and the larger medial head originates from the posterior medial femoral condyle. The medial and lateral heads of the gastrocnemius muscle along with the soleus muscle combine to form the Achilles tendon, which inserts onto the posterior surface of the calcaneus. Since the gastrocnemius muscle crosses three joints including the knee and subtalar joints, it can be vulnerable to injury, especially in mature athletes who experience sudden and swift changes in direction associated with muscular overstretching. Other causes of gastrocnemius muscle injury include maximal knee extension and full ankle dorsiflexion. Since the muscle is already prone to injury, anatomical variations of the gastrocnemius muscles may be symptomatic. With muscle variations, there are potential implications and effects on the other structures within the popliteal fossa. Many different anatomical variations have been identified during routine dissections and reported in the literature. Understanding details of these variations is important for diagnostic, surgical and clinical practice and patient management. Here we report on a 65-year-old White Male cadaveric donor with an accessory lateral head of the gastrocnemius muscle found incidentally during a routine dissection.

Navigated, gap-balanced, adjusted mechanical alignment achieves alignment and balancing goals in a very high percentage but with partially non-anatomical resections.

Navigated, gap-balanced adjusted mechanical alignment (AMA) including a 0° varus tibial cut and modification of angles and resections of the femoral cuts to obtain optimal balance accepting minor axis deviations. Objectives of this study were (1) to analyse to what extent AMA achieves the goals for leg alignment and gap balance, and (2) in what percentage non-anatomical cuts are needed to achieve these goals. Out of 1000 total knee arthroplasties (TKA) all varus knees (hip-knee-ankle (HKA) angle < 178°; n = 680) were included. All surgeries were performed as computer assisted surgery (CAS) in AMA technique. CAS data at the end of surgery were analysed with respect to HKA and gap-sizes. All bone cuts were quantified. Depending on the amount of deformity, a subgroup analysis was performed. It was analysed whether the amount of deformity influences the non-anatomical cuts by correlation analysis. AMA reached the goals for postoperative HKA (3° corridor) in 636 cases (93.5%). While extension and flexion gap balance were achieved in more than 653 cases (96%), flexion and extension gap size were equalled in 615 knees (90.4%). The resections of the lateral tibia plateau and distal and posterior medial femoral condyle were anatomical (Tibia: 7.0 ± 1.7mm; medial condyle distal: 7.8 ± 1.4mm; medial posterior: 8.2 ± 1.8mm). The number of non-anatomical resections for those cuts were low; 67 (9.9%); 24 (3.5%); 32 (4.7%). For the medial tibia plateau and the lateral posterior condyle, the cuts were non-anatomical in a high percentage of cases; Tibia: 606 (89.1%), lateral posterior condyle: 398 (58.5%). Moderate but significant correlations were found between resection differences and amount of deformity (medio-lateral: tibia: 0.399; distal femur: 0.310; posterior femur: 0.167). No correlations were found between resection differences and gap values. AMA reaches the intended target for HKA and gap balance in over 612 (90%) of cases and maintains the medial femoral condyle anatomically. Non-anatomical tibial resection causes increased external rotation of the femoral component and by that non-anatomical cut of the posterior lateral condyle. Nonanatomical resections of AMA might be one reason for the persisting high rate of unsatisfied patients after TKA. Anatomical and individual alignment philosophies might help to reduce this rate of dissatisfaction.

Anterior prominence of the femoral condyle varies among prosthesis designs and surgical techniques in total knee arthroplasty

BackgroundPatellofemoral overstuffing after total knee arthroplasty (TKA) can cause limited range of motion and anterior knee pain. This study compared anterior prominence of femoral components among different prothesis designs in surgical simulation models utilizing the anterior reference (AR) and posterior reference (PR) techniques.MethodsSurgical simulations were performed using on a three-dimensional planning system preoperative computed tomography data of consecutive 30 patients with knee osteoarthritis scheduled to undergo TKA. Four implant models were used: Attune, Persona, Journey II, and Legion. Rotational alignment was set parallel to the transepicondylar axis and size was selected based on the absence of notch formation in the femoral anterior cortex and the best fit with the shape of the medial posterior femoral condyle. For each combination of surgical technique (AR or PR method) and implant model, measurements were taken of the maximum medial, central, and lateral prominence of the implant from the anterior femoral cortex.ResultsUsing either the AR or PR method, the medial and central prominences were significantly lower with Journey II than with the other models. The lateral prominence was the lowest with Attune in the AR method. The AR method was associated with significantly less prominence compared with the PR method, regardless of implant model.ConclusionsThe degree of anterior prominence of the femoral implant is affected by the implant design when the AR method is used. The PR method is associated with greater anterior prominence compared with the AR method, and the pitch size is an additional factor in the PR method. Surgeons should be familiar with implant designs, including the thickness of the anterior flange and the available size selections.

OP0108 LORECIVIVINT (SM04690), AN INTRA-ARTICULAR, SMALL-MOLECULE CLK2/DYRK1A INHIBITOR THAT MODULATES THE WNT PATHWAY, PROVIDED CARTILAGE-PROTECTIVE EFFECTS IN AN ANIMAL MODEL OF POST-TRAUMATIC OA

Background:Osteoarthritis (OA) is characterized by increased cartilage thinning, bone remodeling, and inflammation. Post-traumatic OA, which develops after acute direct trauma to the joints, accounts for approximately 12% of all OA cases.1 Current therapeutic options focus on alleviating symptoms and pain rather than disease modification. Lorecivivint (LOR; SM04690), an intra-articular (IA), small-molecule CLK2/DYRK1A inhibitor that modulates the Wnt pathway, has been shown in animal studies to induce chondrogenesis, protect cartilage, and reduce inflammation and, thereby, improve joint health.2Objectives:A single IA LOR injection was evaluated in a rat model of knee instability to determine its protective and regenerative effects when injected at different timepoints after induction of post-traumatic OA.Methods:Knee instability/post-traumatic OA was surgically induced in rats by combining anterior cruciate ligament transection with partial medial meniscus transection (ACLT+pMMx). LOR (0.3 ug) or vehicle was injected into the IA space of the damaged knee at 2, 3, or 4 weeks after induction of OA. OA-induced (n=10/group) or sham-operated (surgery without ACLT+pMMx; n=5/group) rats were sacrificed at the injection timepoint (baseline) or 12 weeks following LOR/vehicle injection (study conclusion). Histological grades were evaluated using the summed OARSI scores (stage and grade of cartilage damage)3 of the anterior and posterior medial femoral condyle (MFC) and medial tibial plateau (MTP). Weight distribution analysis was performed using an incapacitance meter at several timepoints. Statistical analysis was performed using one-way ANOVA with Dunnett’s multiple comparison test.Results:ACLT+pMMx surgeries led to increased OARSI scores in rats compared with sham surgeries by 2 weeks. LOR treatment at Weeks 2, 3, and 4 led to significant decreases (P&lt;0.05) in total joint OARSI scores (Table 1) at the end of the study compared with vehicle treatment. Rats treated with LOR for 12 weeks and rats at injection baseline had similar OARSI scores, suggesting that LOR treatment arrested the progression of cartilage damage. Significant improvements (P&lt;0.05) were also observed in the weight distribution of LOR-treated rats in the 3- and 4-week groups at 6 and 12 weeks after their respective IA injections compared with vehicle-treated rats.Table 1.OARSI scoresWeek-2 injectionSham-operated(14 weeks after surgery)Baseline (BL)(2 weeks after surgery)Vehicle(12 weeks after injection)LOR(12 weeks after injection)Total score5.9919.1731.3619.19SEM1.071.552.481.81P value versus BL0.9999P value versus vehicle0.0004Week-3 injectionSham-operated(15 weeks after surgery)Baseline (BL)(3 weeks after surgery)Vehicle(12 weeks after injection)LOR(12 weeks after injection)Total score6.0923.1730.4521.20SEM1.251.361.421.00P value versus BL0.4522P value versus vehicle0.0001Week-4 injectionSham-operated(16 weeks after surgery)Baseline (BL)(4 weeks after surgery)Vehicle(12 weeks after injection)LOR(12 weeks after injection)Total score6.9716.8824.9518.63SEM1.321.041.741.61P value versus BL0.6257P value versus vehicle0.0111Conclusion:LOR exhibited cartilage-protective effects and slowed disease progression in the ACLT+pMMx model in vivo and, therefore, has potential as a structure-modifying treatment for OA.

New evaluation indices for rotational knee angles in standing anteroposterior knee radiographs.

Identifying the time course of rotational knee alignment is crucial for elucidating the etiology in knee osteoarthritis. The aim of this study was to propose new rotational indices for calculating the change in relative rotational angles between the femur and tibia in standing anteroposterior (AP) radiographs. Forty healthy elderly volunteers (20 women and 20 men; mean age, 70 ± 6 years) were assessed. The evaluation parameters were as follows: (1) femoral rotational index: the distance between the sphere center of the medial posterior femoral condyle and the lateral edge of the patella, and (2) tibial rotational index: the distance between the medial eminence of the tibia and the lateral edge of the fibula head. The indices were standardized by the diameter of the sphere of the medial posterior femoral condyle. This study (1) identified the relationship between changes in rotational indices and the simulated rotational knee angles in the standing position, (2) proposed a regression equation for the change in relative rotational angles between the femur and tibia in standing AP radiographs, and (3) verified the accuracy of the regression equation. The rotational indices increased in direct proportion to simulated rotational knee angles (femoral index: r > 0.9,p <0.0001; tibial index: r >0.9, p <0.0001). Based on the results, the regression equation with the accuracy of 0.45 ± 0.26° was determined. The proposed regression equations can potentially predict the change in relative rotational angles between the femur and tibia in a pair of standing AP radiographs taken at different dates in longitudinal studies.

High-Density Mineralized Protrusions and Central Osteophytes: Associated Osteochondral Junction Abnormalities in Osteoarthritis.

The aim of this study was to determine the association between high-density mineralized protrusions (HDMPs) and central osteophytes (COs), and describe the varying appearance of these lesions using advanced clinical imaging and a novel histological protocol. Seventeen consecutive patients with clinically advanced knee osteoarthritis undergoing knee arthroplasty were included. Surgical tissues containing the osteochondral region were investigated using computed tomography (CT); a subset was evaluated using confocal microscopy with fluorescence. Tissues from seven subjects (41.2%) contained HDMPs, and tissues from seven subjects (41.2%) contained COs. A significant association between HDMPs and COs was present (p = 0.003), with 6 subjects (35.2%) demonstrating both lesions. In total, 30 HDMPs were found, most commonly at the posterior medial femoral condyle (13/30, 43%), and 19 COs were found, most commonly at the trochlea (5/19, 26.3%). The HDMPs had high vascularity at their bases in cartilaginous areas (14/20, 70%), while the surrounding areas had elevated levels of long vascular channels penetrating beyond the zone of calcified cartilage (p = 0.012) compared to HDMP-free areas. Both COs and HDMPs had noticeable bone-resorbing osteoclasts amassing at the osteochondral junction and in vascular channels entering cartilage. In conclusion, HDMPs and COs are associated lesions in patients with advanced knee osteoarthritis, sharing similar histologic features, including increased vascularization and metabolic bone activity at the osteochondral junction. Future studies are needed to determine the relationship of these lesions with osteoarthritis progression and symptomatology.

New evaluation indexes for estimated rotational knee angles in stading anteroposterior knee radiographs from Matsudai knee osteoarthritis survey

New evaluation indexes for estimated rotational knee angles in stading anteroposterior knee radiographs from Matsudai knee osteoarthritis survey

Comparison of medial and lateral posterior femoral condyle articular cartilage wear patterns

BackgroundWhile degenerative changes to the articular cartilage of the anterior and distal portions of the femoral condyles have been well studied in the literature, the changes that occur on the posterior femoral condyle are not as clear. The purpose of this study was to assess the difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in knees undergoing unicompartmental knee arthroplasty. MethodsA retrospective review of prospectively gathered data on 107 consecutive patients undergoing unicompartmental knee arthroplasty performed by a single surgeon was performed. The remaining articular cartilage thickness after resection of the posterior femoral condyle was measured and simple analysis conducted to compare cartilage thickness between medial and lateral posterior femoral condyles. ResultsNinety-two medial unicompartmental arthroplasties and 15 lateral unicompartmental arthroplasties were performed during the 16 month study period. The majority of lateral UKA patients were female and had lower BMI than medial UKA patients. The articular cartilage thickness on the medial posterior femoral condyle was 3 mm ± 1 mm (mean ± standard deviation) and 1 mm ± 1 mm on the lateral side (p-value <0.001). ConclusionsThere is a significant difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in patients undergoing unicompartmental knee arthroplasty. This coincides with a potentially inherently different pattern of articular cartilage degeneration between the medial and lateral compartments of the knee and has implications on implant designs and resurfacing techniques about the knee.

Associations Between Slower Walking Speed and T1ρ Magnetic Resonance Imaging of Femoral Cartilage Following Anterior Cruciate Ligament Reconstruction.

To determine whether walking speed, collected at 6 and 12 months following anterior cruciate ligament reconstruction (ACLR), is associated with inter-extremity differences in proteoglycan density, measured via T1ρ magnetic resonance imaging, in tibiofemoral articular cartilage 12 months following ACLR. Twenty-one individuals with a unilateral patellar-tendon autograft ACLR (10 women and 11 men, mean ± SD age 23.9 ± 2.7 years, mean ± SD body mass index 23.9 ± 2.7 kg/m2 ) were recruited for participation in this study. Walking speed was collected using 3-dimensional motion capture at 6 and 12 months following ACLR. The articular cartilage of the medial femoral condyle (MFC) and lateral femoral condyle and medial and lateral tibial condyles was manually segmented and subsectioned into 3 regions of interest (anterior, central, and posterior) based on the location of the meniscus in the sagittal plane. Inter-extremity mean T1ρ relaxation time ratios (T1ρ ACLR extremity / T1ρ contralateral extremity) were calculated and used for analysis. Pearson product-moment correlations were used to determine associations between walking speed and inter-extremity differences in T1ρ relaxation time ratios. Slower walking speed 6 months post-ACLR was significantly associated with higher T1ρ relaxation time ratios in the MFC of the ACLR extremity 12 months following ACLR (posterior MFC, r = -0.51, P = 0.02; central MFC, r = -0.47, P = 0.04). Similarly, slower walking speed at 12 months post-ACLR was significantly associated with higher T1ρ relaxation time ratios in the posterior MFC ACLR extremity (r = -0.47, P = 0.04) 12 months following ACLR. Slower walking speed at 6 and 12 months following ACLR may be associated with early proteoglycan density changes in medial femoral compartment cartilage health in the first 12 months following ACLR.

Cartilage Subsurface Changes to Magnetic Resonance Imaging UTE-T2* 2 Years After Anterior Cruciate Ligament Reconstruction Correlate With Walking Mechanics Associated With Knee Osteoarthritis

Background: Anterior cruciate ligament (ACL) injury increases risk for posttraumatic knee osteoarthritis (OA). Quantitative ultrashort echo time enhanced T2* (UTE-T2*) mapping shows promise for early detection of potentially reversible subsurface cartilage abnormalities after ACL reconstruction (ACLR) but needs further validation against established clinical metrics of OA risk such as knee adduction moment (KAM) and mechanical alignment. Hypothesis: Elevated UTE-T2* values in medial knee cartilage 2 years after ACLR correlate with varus alignment and higher KAM during walking. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Twenty patients (mean age, 33.1 ± 10.5 years; 11 female) 2 years after ACLR underwent 3.0-T knee magnetic resonance imaging (MRI), radiography, and gait analysis, after which mechanical alignment was measured, KAM during walking was calculated, and UTE-T2* maps were generated. The mechanical axis and the first and second peaks of KAM (KAM1 and KAM2, respectively) were tested using linear regressions for correlations with deep UTE-T2* values in the central and posterior medial femoral condyle (cMFC and pMFC, respectively) and central medial tibial plateau (cMTP). UTE-T2* values from ACL-reconstructed patients were additionally compared with those of 14 uninjured participants (mean age, 30.9 ± 8.9 years; 6 female) using Mann-Whitney U and standard t tests. Results: Central weightbearing medial compartment cartilage of ACL-reconstructed knees was intact on morphological MRI. Mean UTE-T2* values were elevated in both the cMFC and pMFC of ACL-reconstructed knees compared with those of uninjured knees (P = .003 and P = .012, respectively). In ACL-reconstructed knees, UTE-T2* values of cMFC cartilage positively correlated with increasing varus alignment (R = 0.568). Higher UTE-T2* values in cMFC and cMTP cartilage of ACL-reconstructed knees also correlated with greater KAM1 (R = 0.452 and R = 0.463, respectively) and KAM2 (R = 0.465 and R = 0.764, respectively) and with KAM2 in pMFC cartilage (R = 0.602). Conclusion: Elevated deep UTE-T2* values of medial knee cartilage 2 years after ACLR correlate with 2 clinical markers of increased risk of medial knee OA. These results support the clinical utility of MRI UTE-T2* for early diagnosis of subsurface cartilage abnormalities. Longitudinal follow-up of larger cohorts is needed to determine the predictive and staging potential of UTE-T2* for posttraumatic OA.

Injection site diversity influences sodium hyaluronate distribution on knee cartilage surface: a cadaveric study

Objective To elucidate whether and how injection site diversity influences on the sodium hyaluronate(HA) distribution on cartilage surface of the knee joint. Methods From September 2014 to December 2014, 32 human cadaveric knees were sorted from small to large based on femoral condyle width(FCW) and divided into group I(n=16, odd number, the patella medial approach) and group II(n=16, even number, injected through the medial joint line approach). Knees of both groups were interfused with a 5%(mg∶ml) methylene blue tracer. Each specimen was then simulated a 5°-45° alternating walking for 2 h in the Electro Force platform. Afterwards, all the knee cavities were cut open to examine the range of HA distribution. Based on the eight-zoning classification law for the knee cartilage surface, the coverage area of HA in each zone was scored and the characteristics of HA distribution was depicted, as well as HA zonal distribution diversity between groups were statistically analyzed. Results HA of both patella medial and medial joint line subgroups showed analogical distribution in all zones except the lateral tibial plateau at the time of FCW ≤ 7.0 cm. However, HA coverage through the patella medial approach showed significantly higher distribution scores in the patella zone and the femoral trochlear zone, but significant lower distribution scores in the antero-lateral/postero-lateral femoral condyle, the medial posterior femoral condyle zone and the lateral tibial plateau zone compared with medial joint line approach at the time of FCW > 7.0 cm. Conclusion When delivered through different injection approaches, HA showed analogical distribution characteristics in most zones of the knee cavity in population with a small bodily shape(FCW ≤ 7.0 cm), but significant diverse distribution characteristics in population with a big bodily shape(FCW >7.0 cm). When FCW > 7.0 cm, HA injected through the medial-patellar approach tended to be distributed mainly over the patella-femoral articulation and the anterior knee cavity, while HA injected through the joint line approach tended to be distributed mainly over the tibio-femoral articulation and the posterior knee cavity. Key words: Osteoarthritis, knee; Hyaluronic acid; Patellofemoral joint

Chondrocyte clusters adjacent to sites of cartilage degeneration have characteristics of progenitor cells.

The purpose of this study was to investigate the site-specific characteristics and roles of chondrocyte clusters in human knee osteoarthritis. Cartilage explants were obtained from 45 knees undergoing total knee replacement surgery. The explants were taken from 4 locations in the knee: the medial femoral condyle, the medial posterior femoral condyle (MPC), the lateral femoral condyle, and the lateral posterior femoral condyle (LPC). Cartilage degeneration, cell density, and cell arrangement were compared histologically. A live/dead cell viability assay and immunohistochemical analyses using antibodies against STRO-1, FGF2, and Ki-67 were performed. Cell proliferation and cartilaginous nodule production in MPC and LPC explants in monolayer culture were compared. Finally, MPC cartilage explants were cultured to observe histological changes. The cell density of the MPC explants was higher than that of the LPC because of clustering. MPC explants contained more live cells than the LPC did, and the expression of IHC markers in MPC explants was higher than that in LPC. Chondrocytes from MPC proliferated faster and produced more nodules in monolayer culture than those from the LPC and MPC explants were repaired during organ culture. In conclusion, chondrocyte clusters adjacent to severe cartilage degeneration have specific characteristics, with progenitor and proliferative potential.

Cartilage thickness at the posterior medial femoral condyle is increased in femorotibial knee osteoarthritis: a cross-sectional CT arthrography study (Part 2)

To evaluate the thickness of cartilage at the posterior aspect of the medial and lateral condyle in Osteoarthritis (OA) knees compared to non-OA knees using computed tomography arthrography (CTA). 535 consecutive knee CTAs (mean patient age = 48.7 ± 16.0; 286 males), were retrospectively analyzed. Knees were radiographically classified into OA or non-OA knees according to a modified Kellgren/Lawrence (K/L) grading scheme. Cartilage thickness at the posterior aspect of the medial and lateral femoral condyles was measured on sagittal reformations, and compared between matched OA and non-OA knees in the whole sample population and in subgroups defined by gender and age. The cartilage of the posterior aspect of medial condyle was statistically significantly thicker in OA knees (2.43 mm (95% confidence interval (CI) = 2.36, 2.51)) compared to non-OA knees (2.13 mm (95%CI = 2.02, 2.17)) in the entire sample population (P < 0.001), as well as for all subgroups of patients over 40 years old (all P ≤ 0.01), except for females above 60 years old (P = 0.07). Increase in cartilage thickness at the posterior aspect of the medial condyle was associated with increasing K/L grade in the entire sample population, as well as for males and females separately (regression coefficient = 0.10-0.12, all P < 0.001). For the lateral condyle, there was no statistically significant association between cartilage thickness and OA (either presence of OA or K/L grade). Cartilage thickness at the non-weight-bearing posterior aspect of the medial condyle, but not of the lateral condyle, was increased in OA knees compared to non-OA knees. Furthermore, cartilage thickness at the posterior aspect of the medial condyle increased with increasing K/L grade.

Quantitative Magnetic Resonance Imaging UTE-T2* Mapping of Cartilage and Meniscus Healing After Anatomic Anterior Cruciate Ligament Reconstruction

Background: An anterior cruciate ligament (ACL) injury greatly increases the risk for premature knee osteoarthritis (OA). Improved diagnosis and staging of early disease are needed to develop strategies to delay or prevent disabling OA. Purpose: Novel magnetic resonance imaging (MRI) ultrashort echo time (UTE)–T2* mapping was evaluated against clinical metrics of cartilage health in cross-sectional and longitudinal studies of human participants before and after ACL reconstruction (ACLR) to show reversible deep subsurface cartilage and meniscus matrix changes. Study Design: Cohort study (diagnosis/prognosis); Level of evidence, 2. Methods: Forty-two participants (31 undergoing anatomic ACLR; 11 uninjured) underwent 3-T MRI inclusive of a sequence capturing short and ultrashort T2 signals. An arthroscopic examination of the medial meniscus was performed, and modified Outerbridge grades were assigned to the central and posterior medial femoral condyle (cMFC and pMFC, respectively) of ACL-reconstructed patients. Two years after ACLR, 16 patients underwent the same 3-T MRI. UTE-T2* maps were generated for the posterior medial meniscus (pMM), cMFC, pMFC, and medial tibial plateau (MTP). Cross-sectional evaluations of UTE-T2* and arthroscopic data along with longitudinal analyses of UTE-T2* changes were performed. Results: Arthroscopic grades showed that 74% (23/31) of ACL-reconstructed patients had intact cMFC cartilage (Outerbridge grade 0 and 1) and that 90% (28/31) were Outerbridge grade 0 to 2. UTE-T2* values in deep cMFC and pMFC cartilage varied significantly with injury status and arthroscopic grade (Outerbridge grade 0-2: n = 39; P = .03 and .04, respectively). Pairwise comparisons showed UTE-T2* differences between uninjured controls (n = 11) and patients with arthroscopic Outerbridge grade 0 for the cMFC (n = 12; P = .01) and arthroscopic Outerbridge grade 1 for the pMFC (n = 11; P = .01) only and not individually between arthroscopic Outerbridge grade 0, 1, and 2 of ACL-reconstructed patients (P > .05). Before ACLR, UTE-T2* values of deep cMFC and pMFC cartilage of ACL-reconstructed patients were a respective 43% and 46% higher than those of uninjured controls (14.1 ± 5.5 vs 9.9 ± 2.3 milliseconds [cMFC] and 17.4 ± 7.0 vs 11.9 ± 2.4 milliseconds [pMFC], respectively; P = .02 for both). In longitudinal analyses, preoperative elevations in UTE-T2* values in deep pMFC cartilage and the pMM in those with clinically intact menisci decreased to levels similar to those in uninjured controls (P = .02 and .005, respectively), suggestive of healing. No decrease in UTE-T2* values for the MFC and new elevation in UTE-T2* values for the submeniscus MTP were observed in those with meniscus tears. Conclusion: This study shows that novel UTE-T2* mapping demonstrates changes in cartilage deep tissue health according to joint injury status as well as a potential for articular cartilage and menisci to heal deep tissue injuries. Further clinical studies of UTE-T2* mapping are needed to determine if it can be used to identify joints at risk for rapid degeneration and to monitor effects of new treatments to delay or prevent the development of OA.

The potential effect of anatomic relationship between the femur and the tibia on medial meniscus tears

The anatomic and the kinematical relationships between the femur and the tibia have been previously examined in both normal and diseased knees. However, less attention has been directed to the effect of these relationships on the meniscal diseases. Therefore, we aimed to investigate the impact of femorotibial incongruence on both lateral and medial meniscal tears. A total of 100 images obtained from MRI of 100 patients (39 males and 61 females) were included in the study. Diameters of the medial and the lateral femoral condyles, thicknesses of the menisci, and diameters of the medial and the lateral tibial articular surfaces were measured. The medial meniscus tear was detected in 40 (40%) patients. However, no lateral meniscus tear was found. Significant relationships were found between the diameters of the posterior medial femoral condyle and the medial tibial superior articular surface and between the diameters of the posterior lateral femoral condyle and the lateral tibial superior articular surface. The mean values for the diameter of the medial condyle of the femur, the lateral condyle of the femur, the medial superior articular surface of the tibia, and the lateral superior articular surface of the tibia were found to be significantly higher in cases with meniscus tear compared to cases without meniscus tear. However, no significant difference was present regarding the thicknesses of the medial and the lateral menisci. A positive relationship between the diameter of the posterior medial femoral condyle and the tibial medial superior articular surface was found in cases with (n=40) (r (2)=0.208, p=0.003) and without tear (n=60) (r (2)=0.182, p=0.001). In addition, a significant positive relationship was found between the diameter of the posterior medial femoral condyle and the medial tibial superior articular surface in cases with and without tear. The impact of femorotibial incongruence on the medial meniscus tear is important for the understanding of the lesions.