Tibial tubercle to trochlear groove distance versus tibial tubercle to posterior cruciate ligament distance for predicting patellar instability: a systematic review.

PURPOSE: To determine the reliability and diagnostic accuracy of tibial tubercle-trochlear groove (TT-TG) distance versus tibial tubercle-posterior cruciate ligament (TT-PCL) distance, and to determine cutoff values of these measurements for pathological diagnosis in the context of patellar instability. METHODS: Three databases MEDLINE, PubMed and EMBASE were searched from inception to October 5, 2022 for literature outlining comparisons between TT-TG and TT-PCL in patellar instability patients. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on inter-rater and intra-rater reliability, receiver-operating characteristic (ROC) curve parameters such as area under the curve (AUC), sensitivity and specificity, as well as odds ratios, cutoff values for pathological diagnosis and correlations between TT-TG and TT-PCL were recorded. The MINORS score was used for all studies in order to perform a quality assessment of included studies. RESULTS: A total of 23 studies comprising 2839 patients (2922 knees) were included in this review. Inter-rater reliability ranged from 0.71 to 0.98 and 0.55 to 0.99 for TT-TG and TT-PCL, respectively. Intra-rater reliability ranged from 0.74 to 0.99 and 0.88 to 0.98 for TT-TG and TT-PCL, respectively. AUC measuring diagnostic accuracy of patellar instability for TT-TG ranged from 0.80 to 0.84 and 0.58 to 0.76 for TT-PCL. Five studies found TT-TG to have more discriminatory power than TT-PCL at distinguishing patients with patellar instability from patients who do not. Sensitivity and specificity ranged from 21 to 85% and 62 to 100%, respectively, for TT-TG. Sensitivity and specificity ranged from 30 to 76% and 46 to 86%, respectively, for TT-PCL. Odds ratio values ranged from 1.06 to 14.02 for TT-TG and 0.98 to 6.47 for TT-PCL. Proposed cutoff TT-TG and TT-PCL values for predicting patellar instability ranged from 15.0 to 21.4 mm and 19.8 to 28.0 mm, respectively. Eight studies reported significant positive correlations between TT-TG and TT-PCL. CONCLUSION: TT-TG resulted in overall similar reliability, sensitivity and specificity as TT-PCL; however, TT-TG has better diagnostic accuracy than TT-PCL in the context of patellar instability as per AUC and odds ratio values. LEVEL OF EVIDENCE: Level IV.

The role of substance P on maintaining ligament homeostasis by inhibiting endochondral ossification during osteoarthritis progression.

PURPOSE: Osteoarthritis (OA) is characterized by the degeneration of various tissues, including ligaments. However, pathological changes such as chondrogenesis and ossification in ligaments during OA are still unclear. Substance P (SP), a neuropeptide, has various functions including bone metabolism. This study aimed to analyze the expression and function of SP in OA ligaments, and the therapeutic potential of SP agonists in OA mice. MATERIALS AND METHODS: Expressions of SP, SOX9, and MMP13 were histologically analyzed in the posterior cruciate ligament (PCL) in humans with OA and Senescence-accelerated mouse-prone 8 (SAMP8) mice as a spontaneous OA model. The effect of SP agonists on chondrogenesis was evaluated using human ligament cells. Finally, SP agonists were administered intraperitoneally to destabilized medial meniscus (DMM) mice, and the PCL was histologically evaluated. RESULTS: In PCL of humans and mice, the expression of SP, SOX9, and MMP13 was upregulated as OA progressed, but their expression was downregulated in severe degeneration. SP and SOX9 were co-expressed in chondrocyte-like cells. In ligament cells, SP agonists downregulated SOX9, RUNX2, and COL10A1. On evaluating chondrogenesis in ligament cells, pellet diameter was reduced in those treated with the SP agonists compared to those untreated. Administration of SP agonists ameliorated PCL degeneration in DMM mice. The Osteoarthritis Research Society and ligament scores in mice with SP agonists were significantly lower than those without SP agonists. CONCLUSIONS: SP plays an important role in maintaining ligament homeostasis by inhibiting endochondral ossification during OA progression. Targeting SP has therapeutic potential for preventing ligament degeneration.

Postoperative Magnetic Resonance Imaging of the Knee Ligaments.

In this article, we describe the postoperative appearances of the reconstructed ligaments of the knee focusing on the anterior cruciate ligament (ACL). The expected evolving signal alterations of the graft over time are also reviewed. The postoperative appearance of the ligamentous reconstruction in patients with multiligamentous knee injuries (MLKI) and isolated PCL tears are also discussed.

MRI View of Rehabilitation Methods to Relieve Anterior Cruciate Ligament Injury in Dancers.

In order to solve the problem of the difference in the diagnostic effect of different sequences of magnetic resonance imaging (MRI) examinations for anterior and posterior cruciate ligament injuries, the author proposes an MRI rehabilitation method to relieve anterior cruciate ligament injury in dancers. This method retrospectively analyzed the clinical data of 60 patients with knee anterior and posterior cruciate ligament injuries in our hospital, and all patients were diagnosed with knee anterior and posterior cruciate ligament injuries. All patients underwent MRI 3D sequence and 2D sequence examination successively to compare anatomical measurements. This study aimed at comparing the measurements of the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) between the two examination sequences; comparing the diagnosis; comparing the grading and judgment of the anterior and posterior cruciate ligament injuries of the knee joint between the two inspection sequences; and comparing the diagnostic coincidence rates of the two examination sequences in the complete tear of the anterior and posterior cruciate ligaments of the knee. Experimental results show that, in terms of PCL and ACL, the angle, thickness, and length of two-dimensional MRI examination were significantly different from those of MRI examination and anatomical measurement (P < 0.05); for PCL and ACL, the angle, thickness, and length of 3D MRI were not significantly different from anatomical measurements (P > 0.05). The diagnostic accuracy of 2D MRI was 83.33%, which was lower than 95.00% of 3D MRI (P < 0.05). There was no significant difference in the grading of anterior and posterior cruciate ligament injuries between the two examination sequences (P > 0.05). The diagnostic coincidence rates of 3D MRI and 2D MRI for complete tear of the anterior and posterior cruciate ligaments were 95.55% and 80.00%, respectively (P < 0.05). In conclusion, three-dimensional MRI examination can obtain higher diagnostic value for patients with knee joint anterior and posterior cruciate ligament injury.

The tibial tubercle-posterior cruciate ligament (TT-PCL) distance does not truly reflect the lateralization of the tibial tubercle.

PURPOSE: The role of the tibial tubercle-posterior cruciate ligament (TT-PCL) and tibial tubercle-trochlear groove (TT-TG) in recurrent patellar instability (RPI) remains unclear. This study aims to confirm the validity of the TT-TG and TT-PCL in predicting RPI and to verify whether the TT-PCL can truly reflect the lateralization of the tibial tubercle. METHODS: A total of 50 patients with RPI and 50 controls were recruited and underwent magnetic resonance imaging examinations. The TT-TG, TT-PCL, and tibial tubercle lateralization (TTL) were measured independently by two authors in a blinded and randomized fashion. T-test was used for parametric variances and the Mann-Whitney U and Chi-square tests were used for non-parametric variances. Pearson's product moment correlation coefficients were calculated to determine correlations between the defined measurements. The intraclass correlation coefficient was used to assess the reliability of the measurements. RESULTS: All defined measurements showed excellent intra- and inter-observer reliability. The TT-TG distance, TT-PCL distance, and TTL were significantly greater in the PI group than in the control group. The AUC was highest for the TT-TG distance compared with that for the TT-PCL distance, and TTL were 0.798, 0.764, and 0.769, with the calculated cut-off value of 12.5 mm, 16.5 mm, and 66.1 percentages. There was a moderate correlation (r = 0.595) between the TT-TG distance and TTL, and a weak correlation (r = 0.430) between the TT-PCL distance and TTL. CONCLUSION: Both the TT-TG distance and TT-PCL distance can be measured with excellent reliability on magnetic resonance imaging. The TT-TG distance, rather than the TT-PCL distance, has a better performance in predicting RPI. Most interestingly, the TT-PCL distance cannot reflect the real lateralization of TT. This study provides new information to evaluate TTL in patients with RPI. LEVEL OF EVIDENCE: III.

Association between magnetic resonance imaging characteristics and pathological findings in entire posterior cruciate ligament with mucoid degeneration.

Magnetic resonance imaging (MRI) findings of a tram-track appearance and celery stalk appearance in mucoid degeneration of the cruciate ligament are valuable; however, their pathological basis is unclear. Because these appearances are generally seen throughout the entire ligament, the association between MRI findings and pathological findings must be verified in specimens of the whole degenerated ligament, including the ligamentous attachments to bone. We herein report two cases of mucoid degeneration of the posterior cruciate ligament with osteoarthritis of the knee requiring total knee arthroplasty. The entire degenerated ligament, including the ligamentous attachments to bone, was removed and pathologically evaluated. On pathological examination, the central portion of the lesion showed typical mucoid degeneration, whereas the marginal and adherent portions showed normal ligament tissue, consistent with a tram-track appearance on T2-weighted MRI. The fibrous normal ligament tissues in the longitudinal direction in regions of mucoid degeneration were consistent with a celery stalk appearance on T2-weighted MRI. No mucoid degeneration was found in the attachment area. The tram-track appearance and celery stalk appearance of mucoid degeneration on MRI can be explained by the pathological findings.

Accuracy of tibial tuberosity-trochlear groove distance and tibial tuberosity-posterior cruciate ligament distance in terms of the severity of trochlear dysplasia.

PURPOSE: Increased tibial tubercle-trochlear groove distance (TT-TG) was proposed as one of the main risk factors for patellofemoral instability (PFI). The increased TT-TG distance indicated externalization of the tibial tubercle with the reference of the trochlear groove. However, in the case of severe trochlear dysplasia, the reference point on the trochlear groove was indistinct, and the accuracy of TT-TG was controversial. The purpose of this study was to evaluate the accuracy of TT-TG and TT-PCL in consideration of the mild and severe trochlear dysplasia. METHODS: From 2015 to 2020, MRI findings of consecutive knee joints with PFI symptoms diagnosed in our hospital were retrospectively analyzed. All knees with trochlear dysplasia were diagnosed by longitudinal MRI scan and lateral radiograph. The knees were classified according to the four-type classification system described by Dejour et al. Twenty cases of type A (mild trochlear dysplasia); 20 cases of type B, C, and D (severe trochlear dysplasia); and 20 cases of normal type were selected and divided into normal group (normal trochlea), mild group (type A), and severe group (type B, type C, type D). Tibial tubercle-trochlear groove distance (TT-TG), tibial tubercle-posterior cruciate ligament distance (TT-PCL), and the Dejour classification of trochlear dysplasia were assessed by 2 experienced orthopedics. The reliability of TT-TG distance and TT-PCL distance was tested by intraclass correlation coefficients (ICCs). RESULTS: Comparing the differences between TT-TG and TT-PCL in the normal, mild, and severe groups, the TT-TG and TT-PCL in the mild and severe groups show different meanings (normal, 8.83 ± 3.62 mm vs. 8.44 ± 4.57 mm, P > 0.05; mild, 17.30 ± 4.81 mm vs. 20.09 ± 5.05 mm, P < 0.05; severe, 10.79 ± 4.24 mm vs. 12.31 ± 5.43 mm, P > 0.05). The Pearson correlation coefficient of TT-TG and TT-PCL measurements of trochlear dysplasia were r = 0.480 (mild group, P = 0.032) and r = 0.585 (severe group, P < 0.001). The intra-observer ICCs of TT-TG were r = 0.814 (mild group) and r = 0.739 (severe group). The inter-observer ICCs of TT-TG were r = 0.810 (mild group) and r = 0.713 (severe group). In the normal knee, the Pearson correlation coefficient of TT-TG and TT-PCL was r = 0.787(P < 0.001), the intra-observer ICC of TT-TG was r = 0.989, and the inter-observer ICC of TT-TG was r = 0.978. CONCLUSION: Compared with the mild trochlear dysplasia, the inter-observer and intra-observer correlations of TT-TG measurements decreased in the group of severe dysplastic trochlea (inter-observer ICC, 0.810 vs. 0.713; intra-observer ICC, 0.814 vs. 0.739). In the present study, the determination of TT-TG and TT-PCL distance are of great significance for patients with low-grade trochlear dysplasia. And TT-PCL, without referring to the abnormal trochlear groove, is an effective indicator to measure the lateralization of tibial tuberosity in patients with severe dysplastic trochlea.

Validating the Role of Tibial Tubercle-Posterior Cruciate Ligament Distance and Tibial Tubercle-Trochlear Groove Distance Measured by Magnetic Resonance Imaging in Patients With Patellar Dislocation: A Diagnostic Study.

PURPOSE: To (1) compare these parameters between patients with patellar dislocation and healthy individuals on magnetic resonance imaging measurements, (2) validate the diagnostic capacity of the tibial tubercle-posterior cruciate ligament (TT-PCL) distance and tibial tubercle-trochlear groove (TT-TG) distance, (3) define the pathologic threshold values of these parameters for tibial tubercle osteotomy indication, and (4) compare these values with those of previous studies. METHODS: Seventy patients with patellar dislocation and 70 healthy volunteers were identified. The inter- and intraobserver reliability values were determined using Bland-Altman analysis and the intraclass correlation coefficient (ICC). The diagnostic capacity of the parameters was evaluated using receiver operating characteristic curves and the area under the receiver operating characteristic curve. The data of the control group were used to determine the pathologic threshold values of the measurements. Logistic regression analysis was performed with these pathologic threshold values. RESULTS: Significant differences in the TT-PCL distance (P = .01) and TT-TG distance (P < .001) were found between the study group (21.48 ± 3.18 and 12.91 ± 3.80, respectively) and the control group (20.07 ± 2.99 and 8.46 ± 3.16, respectively). Both the TT-PCL distance and TT-TG distance had excellent inter- and intraobserver agreement, with inter-ICCs >0.915 and intra-ICCs >0.932, respectively. However, the TT-TG distance had a higher area under the receiver operating characteristic curve than did the TT-PCL distance (0.820 vs 0.627). The pathologic threshold value of the TT-PCL distance was 24.76 mm. The pathologic threshold value of the TT-TG distance was 13.64 mm. Subjects with a TT-TG distance of >13.64 mm had a greater risk for patellar dislocation, with an odds ratio of 14.02 (95% confidence interval 4.00-49.08, P < .001). CONCLUSIONS: Both the TT-PCL distance and TT-TG distance can be measured reliably by magnetic resonance imaging; however, the TT-TG distance has a better diagnostic capacity than does the TT-PCL distance. LEVEL OF EVIDENCE: Retrospective cohort study (diagnosis); Level of evidence, I.

The amount of displacement can determine non-operative treatment in posterior cruciate ligament avulsion fracture.

PURPOSE: It is generally agreed that surgical treatment is warranted for acute posterior cruciate ligament (PCL) avulsion fracture with displacement. However, the amount of displacement that warrants surgical treatment has not been defined. The purpose of this study was to determine the optimal cut-off value for displacement of posterior cruciate ligament avulsion fracture in determining non-operative treatment and to compare the results of non-operative treatment in acute isolated PCL avulsion fractures with non-operative treatment of acute PCL injury. METHODS: Between 2007 and 2017, 30 consecutive patients with acute isolated PCL avulsion fractures and 70 consecutive patients with acute isolated PCL injuries, all of whom underwent non-operative treatment (cast immobilization with > 2 years of follow-up) were retrospectively analyzed. Clinical scores including the International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity score, as well as side-to-side differences on stress radiographs, were compared between the PCL avulsion fracture and PCL injury groups at the final follow-up. The failure rates of non-operative treatment were also compared. The predictive value of the amount of fracture displacement for successful non-operative treatment was calculated using area under the receiver operating characteristic curve (AUROC). The optimal cut-off of the amount of fracture displacement to determine non-operative treatment was based on the maximal sum of sensitivity and specificity. RESULTS: The two groups exhibited comparable clinical scores and mean side-to-side differences on stress radiographs. There were 5 (16.6%) failures of non-operative treatment in the PCL avulsion fracture group and 19 (27.1%) failures in the PCL injury group. (n.s) There was a significant positive correlation between the amount of initial avulsion fracture displacement and side-to-side difference in posterior stress radiographs at final follow up (P < 0.001). The optimal cut-off value for the amount of fracture displacement in PCL avulsion fracture to predict failure of non-operative treatment was 6.7 mm (AUROC = 1.0). CONCLUSION: The outcomes of non-operative treatment of acute isolated PCL avulsion fractures were comparable to those of patients with acute isolated PCL injuries. Acute PCL avulsion injuries with displacement of less than 6.7 mm should be considered for non-operative treatment. LEVEL OF EVIDENCE: IV.

Contribution of Habitual Activity to Cruciate Ligament Rupture in Labrador Retrievers.

OBJECTIVE: The aim of this study was to describe the contribution of signalment and habitual activity in the development of cruciate ligament rupture (CR) in Labrador Retrievers. STUDY DESIGN: Four hundred and twelve client-owned purebred Labrador Retrievers were recruited. Dogs were assigned either as affected with CR or as controls based on signalment, physical examination and radiographic evidence of disease. Clients were asked to complete a questionnaire related to signalment, concurrent disease and a questionnaire pertaining to their dog's activity before development of CR or general activity during the dog's most active years. RESULTS: Habitual activity was not significantly different between dogs affected with CR and controls. There was no significant difference in neuter status or body weight between CR affected dogs and controls. Labrador Retrievers with a yellow coat, and Labradors that did not maintain an optimal body weight in the opinion of their veterinarian were at increased risk of developing CR. CONCLUSIONS: Habitual activity level is not a risk factor for development of CR in Labrador Retrievers. Our study did not show neuter status, sex or body weight to be risk factors for CR. However, coat colour and not sustaining optimal body condition are significant risk factors for CR.

Early pre-radiographic structural pathology precedes the onset of accelerated knee osteoarthritis.

BACKGROUND: Accelerated knee osteoarthritis (AKOA) is characterized by more pain, impaired physical function, and greater likelihood to receive a joint replacement compared to individuals who develop the typical gradual onset of disease. Prognostic tools are needed to determine which structural pathologies precede the development of AKOA compared to individuals without AKOA. Therefore, the purpose of this manuscript was to determine which pre-radiographic structural features precede the development of AKOA. METHODS: The sample comprised participants in the Osteoarthritis Initiative (OAI) who had at least one radiographically normal knee at baseline (Kellgren-Lawrence [KL] grade < 1). Participants were classified into 2 groups based on radiographic progression from baseline to 48 months: AKOA (KL grade change from < 1 to > 3) and No AKOA. The index visit was the study visit when participants met criteria for AKOA or a matched timepoint for those who did not develop AKOA. Magnetic resonance (MR) images were assessed for 12 structural features at the OAI baseline, and 1 and 2 years prior to the index visit. Separate logistic regression models (i.e. OAI baseline, 1 and 2 years prior) were used to determine which pre-radiographic structural features were more likely to antedate the development of AKOA compared to individuals not developing AKOA. RESULTS: At the OAI baseline visit, degenerative cruciate ligaments (Odds Ratio [OR] = 2.2, 95% Confidence Interval [CI] = 1.3,3.5), infrapatellar fat pad signal intensity alteration (OR = 2.0, 95%CI = 1.2,3.2), medial/lateral meniscal pathology (OR = 2.1/2.4, 95%CI = 1.3,3.4/1.5,3.8), and greater quantitative knee effusion-synovitis (OR = 2.2, 95%CI = 1.4,3.4) were more likely to antedate the development of AKOA when compared to those that did not develop AKOA. These results were similar at one and two years prior to disease onset. Additionally, medial meniscus extrusion at one year prior to disease onset (OR = 3.5, 95%CI = 2.1,6.0) increased the likelihood of developing AKOA. CONCLUSIONS: Early ligamentous degeneration, effusion/synovitis, and meniscal pathology precede the onset of AKOA and may be prognostic biomarkers.

Classification of Cruciate Ligament Dysplasia and the Severity of Congenital Fibular Deficiency.

BACKGROUND: Dysplasia of the cruciate ligaments has been found in many patients with congenital fibular deficiency. A recent classification system has shown that radiographic tibial spine changes can predict the hypoplasia and aplasia of the cruciate ligaments. We used this radiographic classification to determine the frequency of these abnormalities and how they correlate with the severity of fibular deficiency and lateral femoral condylar hypoplasia. METHODS: Using a hospital database search for fibular deficiency, 99 patients ≥6 years with unilateral fibular deficiency were identified. Existing radiographs of both knees were available for 75 patients and reviewed for the tibial spine changes and Achterman and Kalamchi classification of the fibular deficiency. Measurements of femoral condyle heights in 74 of 75 patients were recorded before any surgery to the distal femoral physis to assess lateral femoral condylar hypoplasia. RESULTS: Twenty-two patients had hypoplasia of the lateral tibial spine+normal medial spine, 29 had absence of the lateral tibial spine+hypoplastic medial spine, and 11 had absence of both tibial spines. Five tibial spines were normal and 8 were unclassifiable. The severity of the tibial spine dysplasia, particularly absence of the lateral tibial spine, correlated with the severity of the fibular deficiency. (P<0.0001) The mean lateral femoral condylar hypoplasia, measured by involved: uninvolved lateral condyle heights, was 0.85±0.11. Those with some preservation of the lateral tibial spine had less lateral femoral condylar hypoplasia (P=0.0009). This lateral femoral condylar hypoplasia was positively associated with the severity of the fibular absence (P=0.039) and foot ray deficiency (P=0.036). CONCLUSIONS: The severity of cruciate ligament dysplasia in fibular deficiency is directly correlated with the severity of fibular absence, lateral femoral condylar hypoplasia, and the absence of foot rays. This suggests that the embryological factors involved have a complex interplay for all of these clinical findings. LEVEL OF EVIDENCE: Level III.

An evidence-based etiology study of synovial cyst of knee cruciate ligament: a real or pseudo-cyst.

PURPOSE: Synovial cyst of knee cruciate ligament (SCKCL) is a rare condition but can cause severe knee pain. The understanding of its etiology is relatively poor. This current study aimed to elucidate the pathogenesis of SCKCL based on a series of histo- and cytopathological examination. METHODS: Ten SCKCL patients who underwent arthroscopy were enrolled, among five patients claimed past knee injury. Hematoxylin & eosin staining was conducted to the cyst wall tissue sections and Papanicolaou staining to the cyst fluid smear. Prussian blue staining was employed to both the wall section and fluid smear. Immumohistochemical staining for mesothelial cells (MC), epithelial cells (CK), vascular endothelial cells (CD31), monocytes (CD68), and hematogenous stem cells (CD117) were taken to elucidate the possible involvement of various cell types in the development of SCKCL. RESULTS: No erythrocyte was discovered in the fluid; however, Prussian blue stained hemosiderin particles were found in the cyst wall and fluid, suggesting past hemorrhage in all patients. Abundant lymphocytes and plasmocytes were observed in the cyst wall and fluid. In addition, the cyst lining was infiltrated with abundant CD68(+) monocytes while only few MC(+) mesothelial cells were sporadically observed in four samples. The cyst submucosa was also diffused with abundant CD68(+) monocytes and proliferated capillaries stained with CD31. CD117-positve hematogenous stem cells were sporadically observed in eight specimens. CONCLUSION: Our findings provided evidence that SCKCL is not a mature synovial cyst but rather an inflammatory pseudo-cyst. It may have resulted from past minor hemorrhage and intra-ligament chronic inflammation.

The detached stump of the torn anterior cruciate ligament adheres to the femoral notch wall and then to the posterior cruciate ligament within 6 months from injury.

PURPOSE: To evaluate the progressive changes in the morphology of traumatic ruptures of the anterior cruciate ligament (ACL) over time. A secondary objective was evaluating their correlation with meniscal tears or chondral lesions. METHODS: The study included one hundred and one patients who underwent ACL reconstruction surgery of the knee after a definite date of injury. The torn ACL remnant morphological pattern was assessed and classified during arthroscopy. A correlation analysis was performed between the pathological features of the remnant and the time length from injury. In addition, correlation between ACL remnant subtypes and meniscal tears or chondral lesions was evaluated. RESULTS: At surgery there were four distinct ACL tear morphological patterns that were correlated to the time span from injury (r = 0.61, p < 0.001) and ended with scarring of the femoral remnant to the posterior cruciate ligament. The early pattern was noticed within median time of 2.6 months from injury and appeared as a separate stump with no scar tissue. The following two patterns appeared within 6 months from injury and were characterized by adhesion of scar tissue to different locations in the femoral notch. The last morphological pattern appeared as adherence of the ACL stump to the posterior cruciate ligament. This pattern was seen in some patients within 6 months from injury but was the dominant pattern later on and was also correlated with meniscal tears. CONCLUSIONS: During the first 3 months from injury the gross morphological features of the torn ACL remnant showed no scar. This phase was followed by scarring of the femoral remnant at first to the femoral notch, and eventually to the posterior cruciate ligament within 6 months from injury and later on. Therefore, further research on the healing potential of the human ACL stump and its biological environment should be focused on the first 3 months from injury. STUDY DESIGN: Case series; Level of evidence, 4.

Bay11-7082 facilitates wound healing by antagonizing mechanical injury- and TNF-α-induced expression of MMPs in posterior cruciate ligament.

Purposes: To investigate the ability of synoviocytes (SCs) in regulating MMPs expression in the posterior cruciate ligament fibroblasts (PCLfs) after TNF-α treatment, to test whether a specific inflammation inhibitor Bay11-7082 can antagonize the expression of MMPs in PCLfs after injury. Methods: The microenvironment of knee joint cavity after PCL injury was mimicked in an in vitro co-culture system. The effects of TNF-α treatment on the expression of MMPs in PCL fibroblasts (PCLfs) were studied. The expression of MMPs mRNA and protein was detected by qRT-PCR and western blot. For the in vivo study, the Bay11-7082 inhibitor was injected into the knee joint cavity after injury, and then were performed on histological analysis. Results: In the mono-culture conditions, 6% mechanical injury upregulated the expression of MMP-2, whereas downregulated MMP-1 and -3, additionally 12% mechanical injury were upregulated all. However, in co-culture conditions, 6% and 12% both significantly increased MMPs expressions. Stretch injury and TNF-α treatment significantly upregulated expression of MMPs mRNA and protein levels in mono-cultured PCLfs. This effect was more significant in PCLfs Plus SCs co-culture system, in which the cells were treated by combination of stretch injury and TNF-α. In addition, Bay11-7082, a specific inflammation inhibitor, could significantly decrease the expression of MMPs induced by stretch injury and/or TNF-α treatment. Less infiltrated inflammatory cells and more integrated tissues were detected in injury PCL 2 weeks after Bay11-7082 treatment, compared to injury group. Immunofluorescent staining showed very low expression levels of MMPs in PCL of Bay11-7082-treated group, compared to the injury groups. Conclusions: SCs sever as the supporting cells that aggravate the TNF-α-induced MMPs accumulation in PCLfs. Inhibition of the expression of MMPs by Bay11-7082 is a promising way to facilitate the self-healing of PCL.

Accuracy of internet images of ligamentous knee injuries.

BACKGROUND: The internet is an easily accessible resource for both providers and patients. Despite this, the internet is not peer reviewed, leaving searches subject to inaccuracies, especially with regards to medical information. The purpose of this study was to review internet images of anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL) tears using two popular search engines: Google and Bing. METHODS: A search query was performed on both Google and Bing for the following terms: 'ACL tear', 'PCL tear', 'MCL tear' and 'LCL tear'. The first 100 images of each individual search were analyzed by three independent orthopedists. RESULTS: The inter-rater reliability was very good for PCL tear on Bing (Cronbach's alpha = 0.89) and excellent (Cronbach's alpha > 0.9) for the remainder of the search queries. When comparing Google to Bing, the only significant difference occurred in the ACL group, with Bing returning a significantly greater number of correct images 60%, 95% CI: 53.2 - 66.7%) compared to Google (45% correct, 95% CI: 38.1-51.8%), p = 0.034. With regards to the other ligaments Bing was more accurate than Google for PCL (39% versus 38%), and LCL (32% to 30%). Both sites were 48% accurate for MCL tear. CONCLUSION: Ultimately, our study revealed that physicians should take an active role in making high quality, easy to understand medical resources and anatomic diagrams available to their patients to avoid confusion and enhance understanding when querying the internet for additional information regarding their condition.

Middle patellar tendon to posterior cruciate ligament (PT-PCL) and normalized PT-PCL: New magnetic resonance indices for tibial tubercle position in patients with patellar instability.

BACKGROUND: To demonstrate whether the distance between the middle point of the patellar tendon and posterior cruciate ligament (PT-PCL) calculated on a single axial MR image could be an alternative measure to tibial tubercle-PCL (TT-PCL) distance for TT lateralization without the need of imaging processing. To show that normalization of PT-PCL (nPT-PCL) against the maximum diameter of the tibial plateau may help to identify patients with patellar instability (PI). METHODS: MR scans of 30 patients (13 females, age 32 ±â€¯13 years) with known PI and 60 patients (31 females, age 39 ±â€¯19 years) with no history of PI were reviewed. Two operators calculated TT-PCL, and PT-PCL nPT-PCL. Intraclass correlation coefficient, Student's t-test, Receiver Operator Characteristic curves, Spearman's Rho and McNemar's test were used. RESULTS: Interobserver reproducibility was 0.894 for PT-PCL for TT-PCL (95% CI = 0.839-0.930) and 0.866 for TT-PCL (95% CI = 0.796-0.912). The PT-PCL was 23.5 ±â€¯3.8 mm in patients and 20.0 ±â€¯2.7 mm in controls (P < 0.001). The TT-PCL was 22.9 ±â€¯3.9 mm in patients and 20.5 ±â€¯2.7 mm in controls (P = 0.002). Correlation between the PT-PCL and TT-PCL was R = 0.838, P < 0.001. The PT-PCL had 66.6% (95% CI = 0.542-0.790) diagnostic yield. The nPT-PCL was significantly higher in patients (0.302 ±â€¯0.03) than controls (0.271 ±â€¯0.03; P < 0.001) with 73.9% (95% CI = 0.628-0.851) diagnostic yield. CONCLUSION: The PT-PCL correlated with TT-PCL, with 66.6% diagnostic yield. The nPT-PCL may represent an additional index, with 73.9% diagnostic yield.

Clinical manifestation and arthroscopic treatment of symptomatic posterior cruciate ligament cyst.

BACKGROUND: Ganglion cyst of cruciate ligaments is a rare lesion; the prevalence is 0.3-0.8%. The purpose of this study was to present clinical features of symptomatic posterior cruciate ligament (PCL) cyst, introduce the arthroscopic excision technique, and evaluate the clinical outcome. METHODS: A series of 11 patients with symptomatic PCL cyst from November 2012 to December 2014 were involved in this retrospective study. Detailed medical history collecting and physical examination were conducted. Magnetic resonance imaging (MRI) scan was used to confirm the diagnosis. Arthroscopic resection was performed, and the sample of the cyst was taken for pathologic examination. The follow-up averaged 30.7 months. International Knee Documentation Committee (IKDC) score, the range of motion (ROM), and MRI evaluations were obtained pre- and postoperatively to assess the surgical outcome. SPSS software was used for statistics analysis. RESULTS: Eight males and 3 females with 6 left knees and 5 right knees were enrolled, the mean age was 34.4 years, and the duration of symptom was 19.0 months. All cases had a definite history of knee trauma or injury. The most common symptom was knee pain at flexion or in flexion-associated activities. MRI revealed the location and size of the cyst in each case. Pathologic examination showed the cyst wall was composed of dense fibroconnective tissue and widespread thick bundles of collagen, which is similar to the structure of ganglion cyst. At the final follow-up, MRI evaluation showed no cyst recurrence. The preoperative ROM and IKDC score were 2.3° to 108.6° and 40.5 ± 11.3, respectively, compared with the postoperative ROM and IKDC score which were 0° to 134.1° and 85.5 ± 4.8 (p < 0.05) separately. CONCLUSIONS: We conclude that the etiology of symptomatic PCL cyst is most likely associated with trauma, pain on flexion is a typical manifestation of symptomatic PCL cyst, MRI evaluation is an ideal examination for the diagnosis, and arthroscopic resection of symptomatic PCL cysts has a good outcome with no recurrence.

Histopathological analysis of the posterior cruciate ligament in primary osteoarthritis.

BACKGROUND: According to some authors, the indication of an arthroplasty maintaining the posterior cruciate ligament (PCL) demands adequate structural preservation and proprioceptive function of this ligament. The nervous fibers contained in the synovial neurovascular bundle (NVB) around the PCL are involved in proprioception. A study evaluating the grade of PCL and NVB degeneration by using clinical, radiological, and perioperative parameters in knee arthritis patients, in theory, could help surgeons in the decision of preserving or not preserving the PCL in a particular patient. QUESTIONS: (1) Can the degree of the PCL collagen fibers degeneration be predicted by clinical, radiographic, and perioperative parameters in knee arthritis patients? (2) Is the NVB histological degeneration status predictable using clinical, radiographic, and perioperative parameters in the same subset of patients? (3) Is there a correlation between the degree of the PCL collagen fibers degeneration and NVB status in knee arthritis patients? METHODS: Eighty-nine PCLs (85 patients) obtained from total knee replacement surgery were studied. The histologic degeneration of PCL collagen fibers and the NVB status (preserved, degenerated, not detected) were evaluated. These histological degeneration patterns were correlated with clinical and radiographic parameters and with anterior cruciate ligament (ACL) status. RESULTS: A small prevalence of preserved NVB was related to Grades IV and V of Ahlbäck's classification, ACL absence, and severe PCL degeneration. The clinical and radiological parameters studied were not able to predict the grade of histological degeneration of the PCL. CONCLUSIONS: Ahlbäck's classification and ACL status provided useful information about NVB integrity. LEVEL OF EVIDENCE: Basic Science Level IV.