Infrapatellar Plica Research Articles

Morphometric and Histological Analysis of the Ligamentum Mucosum of the Knee Joint: A Descriptive Study

Background: The ligamentum mucosum (LM), or the infrapatellar plica, is a synovial fold of the knee joint that extends between the infrapatellar pad of fat and the intercondylar notch of the femur. LM has been implicated in plica syndrome, a painful knee condition caused by thickened, fibrotic, and edematous synovial plicae. LM can be used to reconstruct an anterior cruciate ligament tear. The present cadaveric study aims to describe the gross and histological features of LM. Methodology: In 20 adult cadavers, the intra-articular structures of the knee joint were exposed by reflecting the patella. LM and its type were identified. The length, width, and thickness were measured. The structure of LM was studied using hematoxylin and eosin stains. Results: LM was present in all the knees. Type 1 was predominant with a single band and was observed in 85%. Type 2a and type 2b were presented with double bands and triple bands, respectively. Type 3 LM was a vertical septum dividing the joint cavity into two compartments. The length of the ligament was 28.16 ± 2.35 mm. The thickness of LM at the proximal and distal end was higher on the left side, which was statistically significant. LM was composed of dense connective tissue and had rich vascularization. Conclusion: LM was initially thought to be incidental, but recent studies have changed the view, and the present study confirms its presence and describes its anatomical features. Knowledge about the LM is necessary to evaluate anterior knee pain when no other pathology is detected.

The infrapatellar plica of the knee: analysis of relationship with femoral trochlear chondrosis using radiographs and 3.0-T MRI.

To assess the relationship of the infrapatellar plica (IPP) with femoral trochlear chondrosis (FTC) using radiographs and 3.0-T MRI. Four hundred eighty-three knees of 476 patients undergoing radiography and MRI were reviewed, and 280 knees of 276 patients were included. We performed a comparison of the frequency of the IPP between men and women, and that of FTC and chondromalacia patella between knees with and without the IPP. In knees with the IPP, we analyzed the correlation between FTC and sex, age, laterality, Insall-Salvati ratio (ISR), femoral sulcus angle, tilting angle, height of insertion of the IPP to Hoffa's fat pad, and width of the IPP. The IPP was found in 192 of 280 knees (68.6%) overall and was more common in men than in women (100 of 132 [75.8%], 92 of 148 [62.2%], p = 0.01). FTC was observed in 26 of 280 (9.3%) and was only in knees with the IPP (knees with the IPP: 26 of 192 [13.5%], knees without the IPP: 0 of 88 [0%], p < 0.001). In knees with the IPP, ISR was significantly greater in knees with FTC (p = 0.002). ISR was the only significant factor associated with FTC (odds ratio: 2.87, 95% confidence interval: 1.14, 7.22, p = 0.03), and the cutoff value of ISR for FTC was > 1.00 with sensitivity of 69.2% and specificity of 63.9%. Presence of the IPP combined with ISR > 1.00 was correlated with FTC.

Infrapatellar plica injury: Magnetic resonance imaging review of a neglected cause of anterior knee pain.

Synovial plicae are normal remnants of synovial membranes within the knee joint cavity and are usually asymptomatic. Pathological infrapatellar plica, which is mostly due to plica injury, may be a potential cause of anterior knee pain, but is often overlooked and under-reported on magnetic resonance imaging (MRI). This pictorial review illustrates the MRI findings of infrapatellar plica injury and associated knee injuries, with emphasis on its differentiation from the mimics of plica injury.

Orthopedic Nursing Based on Preoperative Diagnosis of Infrapatellar Plica Using Medical Imaging

Purpose: We investigate the diagnostic value and therapeutic effect of arthroscopy on the knee synovial fold syndrome. Methods: Thirty patients (35 knees) who has knee subgingival fold syndrome were treated with knee arthroscopy and medial temporal synovectomy. All these patients in this group were treated with epidural anesthesia and underwent arthroscopic surgery. MRI was used initially to diagnosis the orthopedic conditions before surgical intervention. At the second observation, it can be seen that the inner wrinkle is hard and it has a white cord-like shape. Generally, the wrinkled wall is fan-shaped, while some of the wrinkled walls are continuous with the upper, lower and outer wrinkles. Changes were evaluated using the Lysholm score in knee function before and after surgery. Results: The treatment is demonstrated: the preoperative average Lysholm score (51.37 ± 6.36), the average Lysholm score (93.00 ± 5.04), and the average improvement of 42 points. The difference between the preoperative and postoperative functional scores was statistically significant (t = 15.283, P &lt; 0.05). Discussion: There are many reports on the synovial wrinkle syndrome in the knee synovial fold syndrome, and the report of the subclinical fold syndrome is extremely rare, and it is considered to be only a manifestation of other syndromes. This aspect shows that the incidence of the knee synovial fold syndrome is relatively low, on the other hand, it also shows that the current understanding of the knee synovial fold syndrome is insufficient. The knee synovial fold syndrome lesions occur mostly in young men and young adults, and are associated with trauma and excessive use of injuries, but the knee synovial fold syndrome and signs are not specific, easily misdiagnosed, and need to be diagnosed under arthroscopy. Arthroscopic treatment of the knee synovial fold syndrome is simple and safe, with less damage and quick recovery after surgery. Conclusion: Arthroscopy has obvious diagnostic value and good therapeutic effect on the knee synovial fold syndrome.

Medical imaging and diagnosis of subpatellar vertebrae based on improved Laplacian image enhancement algorithm

ObjectiveNowadays, arthroscopy is widely applied to the treatment of joint diseases. The experimental trials were designed to determine whether the infrapatellar plica was symptomatic or not, and to appraise the medical effects of these patients who underwent arthroscopic treatment. An improved Laplacian image enhancement algorithm is added to the experiment. The medical image of the Subpatellar vertebral body under arthroscope is processed by the algorithm. The processed image is compared with the original image, and the advantages and disadvantages of the improved Laplacian image enhancement algorithm are analyzed. MethodsRetrospective Medical trial design was executed in our study. In addition, X-ray film and magnetic resonance imaging (MRI) were included in the study. Visual Analogue Scale (VAS) and Lysholm Score were carried out. Arthroscopy results, MRI findings, and Medical features were researched and analyzed carefully. Then we use the improved Laplacian image enhancement algorithm to process the image, which makes the image more convenient for analysis and improves the diagnostic accuracy. ResultsSome of the experimental protomedical images are not clear enough, and the details and textures are difficult to judge, which hinders the diagnosis. After the improved Laplacian algorithm processing, the image effect has been significantly improved. From the image we get the result, although the wound healed after surgery, some patients have existence of transient swelling in recovery process but no effusion. The pain of all patients knee was sharply relieved and the function was improved. All patients’ conditions were most satisfactory. ConclusionThe findings in this study demonstrate a significant reduction in knee pain and improvement in function by releasing and removal of the symptomatic infrapatellar plica under arthroscopic surgery. The image processed by the improved Laplacian image enhancement algorithm can effectively retain the image details, which is conducive to diagnosis and improve the diagnostic accuracy.

Arthroscopic Untethering of the Fat Pad of the Knee: Release or Resection of the Infrapatellar Plica (Ligamentum Mucosum) and Related Structures for Anterior Knee Pain

Anterior knee pain (AKP), a multifactorial symptom complex, can be successfully treated surgically. A specific diagnosis often cannot be made, but the pain is linked to an unrecognized common factor in most patients: the mechanical behavior of the non-isometric contents of the anterior compartment of the knee—the fat pad (FP) and infrapatellar plica (IPP). The objective of this presentation is to describe an effective arthroscopic technique that treats AKP by addressing this common factor. The operation consists of release or resection of the IPP, or ligamentum mucosum, which tethers the FP. These highly innervated tissues act together as a hydraulic shock absorber, filling the anterior compartment. They stretch and deform at the extremes of knee motion because of constraint centrally by the non-isometric IPP. These dynamic changes in shape are eliminated when the plica is released or resected. Pain perception is from perturbed nociceptive nerves: pain relief results from de-tensioning these contained nerves by untethering the fat pad. Ascribing pain causation is problematic because morphologic change, such as inflammation, fibrosis, or contracture of these structures, is only present in a minority of cases. Nonetheless, AKP is both physically linked to these central, pain-sensitive structures and relieved by this operation.

The Morphological &amp; Biomechanical Characteristics of the Ligamentum Mucosum and its Potential Role in Anterior Knee Pain

IntroductionThe ligamentum mucosum (LM), or infrapatellar plica, is a non‐isometric structure of the knee joint that traverses from the intercondylar notch of the femur to the infrapatellar fat pad. The LM is composed of dense regular connective tissue, of which four different morphologies have been identified: separate, vertical septum, split, and fenestrated. Microscopically, pathological LM appears fibrotic and calcified, which can lead to impingement, and ultimately may be implicated in the pathogenesis of anterior knee pain. The specific aims of this study are to investigate the anatomical relationship of the LM to neighboring structures, determine whether the histological characteristics of the LM further define its function and its potential role in proprioception, and lastly to perform an in vitro biomechanical analysis of the LM under normal physiological loading.MethodologyFresh‐frozen cadaveric knee specimens (n=14) were dissected to reveal the structures of the joint capsule and to identify the morphology of the ligamentum mucosum. With the knee at 90° flexion, four measurements were recorded in order to examine the important relationships within the joint capsule. The intraclass correlation coefficient was calculated to determine the consistency and reproducibility of the measurements recorded. Maintaining the proximal and distal attachments, two specimens were harvested for histological analysis using standard hematoxylin and eosin, Masson's trichrome for collagen, and mono‐clonal mouse anti‐human neurofilament protein to identify neurons and peripheral nerve endings.ResultsOverall, 64% of the knees had a LM present. With respect to morphology, 50% of the 14 specimens had a separate type, 14% had a vertical septum type, and the remaining specimens had no LM present, which is consistent with known classification systems. The histological analysis confirmed the LM to be ligamentous, thus being composed of dense regular connective tissue. Preliminary immunohistochemistry results are inconclusive at this time for evidence of peripheral nerves and nerve endings, and the biomechanical properties of LM have yet to be determined.DiscussionThe role of LM in anterior knee pain is not well documented; however, studies have shown that excising the LM can relieve idiopathic anterior knee pain. With a decrease in elasticity, pathological LM may result in patellar maltracking and instability, ultimately triggering anterior knee pain. Future biomechanical testing will utilize an Instron materials testing machine to load the ligaments under tension at a constant velocity in order to determine the force at which the specimen fails. Thus, the findings from this study can be implemented in models of anterior knee pain, more specifically models of patellar instability and maltracking, to determine the proprioceptive and pathogenic mechanisms of the ligamentum mucosum.

Intra-Operative fluoroscopic findings demonstrate deformation of the infrapatellar plica and fat pad with knee motion; release of the infrapatellar plica eliminates the distortion establishing an anatomic link to anterior knee pain

Intra-Operative fluoroscopic findings demonstrate deformation of the infrapatellar plica and fat pad with knee motion; release of the infrapatellar plica eliminates the distortion establishing an anatomic link to anterior knee pain

Kinematics of the Fat Pad, its Central Body, and the Infrapatellar Plica, Newly Described as a Non‐Isometric Ligament of the Knee

We have described the infrapatellar plica (IPP) of the knee as a non-isometric ligament, attaching the fat pad (FP) to the femur. We had noted during knee arthroscopy that the IPP showed mechanical behavior, stretching and relaxing with motion, and holding the FP against the distal femur. We sought to visualize the kinematics of this behavior using fluoroscopy in cadavers and, in an Institutional Review Board approved study of human volunteers undergoing arthroscopy. With radiographic contrast injected in the IPP, we demonstrated in cadavers and in vivo, that the FP, highly innervated central body (CB), and IPP rotate around the femoral attachment (FA) of the IPP. The fluoroscopic films show a sequence starting in flexion, of stretch and distortion of the IPP and CB, then relaxation throughout mid arc and, remarkable stretch and distortion approaching full extension. This confirmed the non-isometric nature of the IPP. The overlying FP as seen in the second figure was tethered centrally by the IPP, and distorted throughout. Release of the IPP at the FA, which has been shown to reduce or eliminate anterior knee pain (AKP), eliminated the distortion of the FP. This kinematic, demonstrating mechanical perturbation of innervated central structures in the knee, introduces a new central vector, altering traditional patellofemoral biomechanics and suggests an altered concept in the causation of knee pain.

The Infrapatellar Plica ‐ a New Intra‐Articular Ligament of the Knee

The infrapatellar plica (IPP) is considered to be an embryological remnant, a synovial fold of no mechanical importance. Its tissue characterization has not been described in the English literature. We had noted during knee arthroscopy that the IPP appeared ligament-like, and showed mechanical behavior, stretching and relaxing with motion, and holding the FP against the distal femur. Seeking to determine its gross and microscopic structure and link it to the observed behavior, we dissected 12 cadaver knees, noting for each the gross anatomy, histology of the IPP and attached fat pad (FP). According to the classification by Kim, the IPP types were: 8 separate, 1 split, 2 fenestrated, and 1 vertical septum. The IPP is a non-isometric ligament, with typical ligamentous structure at its femoral attachment (FA), a typical enthesis, and its rope-like central zone (CZ), primarily dense fibrous bundles of collagenous tissue. The structure of the attachment of the IPP to the FP at the central body (CB) is unique and consists of a splaying out of finger-like collagenous septa that merge with those of the FP. There is abundant elastase staining consistent with the distortion associated with knee motion. Lodged in the axillae of these septa are fat lobules similar to those of the FP, but containing a rich plexus of neurovascular bundles, which show wavy redundancy also correlating with the observed mechanical behavior. The IPP/CB/FP complex can be linked to chronic anterior knee pain in that arthroscopic release of the FA relieves the pain in most.

The infrapatellar fat pad and plica – gross anatomy, and histology suggesting that the infrapatellar plica functions as an intra-articular ligament: a preliminary report

The infrapatellar fat pad and plica – gross anatomy, and histology suggesting that the infrapatellar plica functions as an intra-articular ligament: a preliminary report

Resection of the infrapatellar plica for adolescent anterior knee pain: successful treatment with long-term follow-Up

Resection of the infrapatellar plica for adolescent anterior knee pain: successful treatment with long-term follow-Up

“What's Going On Between the Condyles?”

The femoral intercondylar notch is a complex 3-dimensional space that can be difficult to evaluate using 2-dimensional images. Normal structures residing in the femoral intercondylar notch are the cruciate ligaments. Several normal variants also course through the femoral intercondylar notch, including the meniscofemoral ligament, intermeniscal ligament, oblique meniscomeniscal ligament, and infrapatellar plica. Abnormalities within the femoral intercondylar notch include internal derangements (i.e., cruciate ligament rupture and bucket-handle meniscal tears) and masses (i.e., intra-articular ganglion [cyst], intra-articular body, pigmented villonodular synovitis, arthrofibrosis, and synovial hemangioma). Radiologic signs can signify abnormalities within the femoral intercondylar notch or elsewhere in the knee, including empty notch sign, double posterior cruciate ligament sign, double anterior cruciate ligament sign, and reversed double posterior cruciate ligament sign. The shape of the femoral intercondylar notch and the presence of meniscal variants can be predictors of future pathology. This article discusses the anatomy and pathology of the femoral intercondylar notch.

Infrapatellar plica of the knee: Revisited with MR arthrographies undertaken in the knee flexion position mimicking operative arthroscopic posture

PurposeTo describe the appearance of the infrapatellar plica (IPP) on magnetic resonance arthrography (MRA) taken in 70° knee flexion, corresponding to the arthroscopic posture. Materials and methodsTwenty-two patients (23 knee joints) who underwent MRA with 70° knee flexion were enrolled. All patients underwent MRA with 70° knee flexion to simulate operative arthroscopy. The images included fat-suppressed T1-weighted spin echo axial, sagittal, and coronal images. The visualization and morphology of the IPP were retrospectively assessed by two musculoskeletal radiologists. ResultsThe IPP was demonstrated in 78.3% (n=18/23) and was best visualized on the sagittal section through the intercondylar notch. The IPP manifested as a linear hypointense structure with variable thicknesses. The intercondylar component was delineated clearly, arising from the anterior intercondylar notch in parallel with the ACL and curving gently downward to attach to the infrapatellar fat pad. On the other hand, the Hoffa's fat pad component was not depicted clearly. The morphology of the IPP was either a separate type (60.9%) or a split type (17.4%). ConclusionThe IPPs can be visualized with a high rate of detection and various morphologic appearances must be appreciated under the review of a flexed knee MRA.

Hoffa’s Disease In A Skeletal Immature Patient With Plica Syndrome - A Rare Case Report

A rare case of Hoffa’s disease in a skeletal immature patient with infrapatellar plica is presented. It was diagnosed by MRI and clinically confirmed and treated with a complete resection of the lesion. However, delay in the diagnosis and treatment ended the professional career of the player.

Evaluation and Treatment of Disorders of the Infrapatellar Fat Pad

The infrapatellar fat pad (IFP), also known as Hoffa's fat pad, is an intracapsular, extrasynovial structure that fills the anterior knee compartment, and is richly vascularized and innervated. Its degree of innervation, the proportion of substance-P-containing fibres and close relationship to its posterior synovial lining implicates IFP pathologies as a source of infrapatellar knee pain. Though the precise function of the IFP is unknown, studies have shown that it may play a role in the biomechanics of the knee or act as a store for reparative cells after injury. Inflammation and fibrosis within the IFP, caused by trauma and/or surgery can lead to a variety of arthrofibrotic lesions including Hoffa's disease, anterior interval scarring and infrapatellar contracture syndrome. Lesions or mass-like abnormalities rarely occur within the IFP, but their classification can be narrowed down by radiographical appearance. Clinically, patients with IFP pathology present with burning or aching infrapatellar anterior knee pain that can often be reproduced on physical exam with manoeuvres designed to produce impingement. Sagittal MRI is the most common imaging technique used to assess IFP pathology including fibrosis, inflammation, oedema, and mass-like lesions. IFP pathology is often successfully managed with physical therapy. Passive taping is used to unload or shorten an inflamed IFP, and closed chain quadriceps exercises can improve lower limb control and patellar congruence. Training of the gluteus medius and stretching the anterior hip may help to decrease internal rotation of the hip and valgus force at the knee. Gait training and avoiding hyperextension can also be used for long-term management. Injections within the IFP of local anaesthetic plus corticosteroids and IFP ablation with ultrasound guided alcohol injections have been successfully explored as treatments for IFP pain. IFP pathology refractory to physical therapy can be approached through a variety of operative treatments. Arthroscopic partial resection for IFP impingement and Hoffa's disease has showed favourable results; however, total excision of the IFP performed concomitantly with total knee arthroplasty (TKA) resulted in worse results when compared with TKA alone. Arthroscopic debridement of IFP fibrosis has been successfully used to treat extension block following anterior cruciate ligament reconstruction, and arthroscopic anterior interval release has been an effective treatment for pain associated with anterior interval scarring. Arthroscopic resection of infrapatellar plicae and denervation of the inferior pole of the patella have also been shown to be effective treatments for refractory infrapatellar pain.

Does an abnormal infrapatellar plica increase the risk of chondral damage in the knee

the aim of this study was to evaluate abnormal infrapatellar plicae that cause chondral lesions on the patellofemoral sulcus and superior aspect of intercondylar notch. in this study, 133 abnormal infrapatellar plicae were evaluated. The abnormal infrapatellar plicae may lead to chondral lesions on the superior portion of intercondylar notch and on the inferior portion of the patellofemoral sulcus with striking, friction, and compression forces during knee motion. the chondral lesions that were caused by abnormal infrapatellar plicae were more severe than the chondral lesions that were caused by normal infrapatellar plicae. The width of the plica did not affect the severity of chondral lesions. abnormal infrapatellar plicae might be one of the causes of chondral lesions on the superior portion of intercondylar notch and on the patellofemoral sulcus. The width of the plica did not affect the severity of chondral lesions.

Anomalous insertion of the medial meniscus into the anterior cruciate ligament: the MR appearance

The aim of this study was to determine the characteristic MR findings of the anomalous insertion of the medial meniscus (AIMM) into the anterior cruciate ligament (ACL), and to document potential pitfalls in its interpretation. We reviewed 1326 consecutive knee arthroscopic studies to identify patients with an AIMM. 30 knees of 26 patients (4 females, 22 males; average age, 31.3 years; range, 14-50 years) were included in this study. We evaluated the presence of an AIMM and analysed the MR findings, including the ACL attachment sites of the AIMMs, the absence of the transverse ligament, meniscal tears and a discoid meniscus. AIMMs were detected by MR imaging in 16 knees of 18 patients (60%, 18/30). The AIMMs showed a linear band with low signal intensity on T2 weighted sagittal images running parallel to the ACL. The AIMMs were inserted into the lower portion of the ACL in eight knees, the middle portion in five knees, and the intercondylar notch in five knees. Meniscal tears (10 medial, 10 lateral) were found in 20 knees of 16 patients. Six knees of five patients showed a discoid meniscus. 15 knees of 14 patients showed no transverse ligament on MR imaging. An AIMM has the potential to be misinterpreted as a meniscal tear, ACL tear or infrapatellar plica on knee MR imaging. Familiarity with the characteristic MR findings can aid in the detection of an AIMM into the ACL.

Symptomatic Lateral Patellar Plica: A Case Report

The plica is a remnant of the synovial folds during the coalescence of three compartments of the knee at 8 weeks of fetal development. The plica are classified according to their corresponding anatomic sites of the knee, such as suprapatellar, medial patellar, infrapatellar and lateral patellar plica. The medial patellar plica is considered to be the one most likely to cause problems and has been well documented in the literature. However, there are very few reports of problems being caused by lateral plica. We encountered one case of pathologic lateral plica that was excised by arthroscopy. We report this case with a review of the relevant literature.

Symptomatic infrapatellar plica

To assess the clinical outcomes of a group of patients who underwent arthroscopic infrapatellar plica (IPP) excision and to determine, whether the IPP was symptomatic or not, to identify the symptoms or signs in the patient's clinical presentation and to study the correlations between arthroscopic findings and patient's clinical presentation. A retrospective clinical study. We studied all the patients undergoing arthroscopic resection of symptomatic infrapatellar plica without other intraarticular abnormality at our department from February 1996 to April 2001. Fourteen patients with isolated IPP and with regular follow-up intervals were included in the study. Arthroscopy findings, preoperative magnetic resonance imaging (MRI) findings, and clinical presentation were correlated. The mean duration of follow-up was 36 months with a range of 24-60 months. The IPP was found to be in fenestra pattern in seven patients, separate (cordlike) pattern in five patients and vertical septum pattern in two patients. IPP in all patients was excised with a powered instrument. Two patients were rated as excellent, ten patients as good and two patients as poor results. All the patients were documented with pain, popping or snapping with flexion and extension, giving way and swelling. There was no correlation between IPP type and MRI findings with being symptomatic (P>0.05). It was found that IPP type was not a prognostic factor. Infrapatellar plica should be considered as a potential cause of knee pain with probable MRI imaging and no other evidence of internal derangement. We recommend close correlation with the clinical symptoms and exclusion of other internal derangement before suggesting infrapatellar plica as a sole cause for knee symptoms.