Infrapatellar plica as a cause of anterior knee pain

The ligamentum mucosum's potential as a preventative structure in the development of knee osteoarthritis

PURPOSE

This paper aimed to identify whether the presence, type, and/or morphology of the ligamentum mucosum could play a role in the development of knee osteoarthritis. Since its microscopic structure is alike that of other knee ligaments, it was hypothesized that its presence could facilitate knee motion and stability, thus preventing or reducing the extent of knee osteoarthritis.

METHODS

Thirty three cadavers (a total of 51 knees) were dissected. The ligamentum mucosum, if present, was measured with a digital caliber and a measuring tape in terms of length, width, and thickness. Knee osteoarthritis was assessed in six regions of the knee. The OuterBridge Classification System (Grades 0-4) was used to visually assess the extent, in addition to probing the area. Osteoarthritis was deemed present if the grade was 2 or greater.

RESULTS

The presence of the ligament was associated with a lower mean osteoarthritis level in the trochlear groove and lateral tibial plateau regions (p < 0.001 and p = 0.013, respectively). Overall osteoarthritis of the knee was also present at varying levels for each type of the ligamentum mucosum (p < 0.001). The patella and the medial condyle had the greatest levels of osteoarthritis, while the medial and lateral tibial plateaus had the lowest levels.

CONCLUSION

The presence of the ligamentum mucosum is linked with decreased osteoarthritis in the trochlear groove region. In addition, both the absent ligament and its classification as a vertical septum are associated with increased knee osteoarthritis.

LEVEL OF EVIDENCE

Five.

Immunohistochemical Analysis of the Ligamentum Mucosum is the Key to Understand its Clinical Usefulness

Ligamentum Mucosum(LM) is a ligamentous structure within the synovial layer of the knee joint capsule. For a long time LM was perceived as the vestigial remnant from the embryological development of the knee. Being treated as an irrelevant structure LM was often the first victim of shaver during arthroscopy. However, last years have shown increased interest in this structure due to its potentially significant clinical role. Our aim was to classify LM based on its morphological characteristics and examine its microanatomy using immunohistochemical analysis to reveal the potential clinical value for surgeons. We have examined sixteen fresh frozen lower limbs, 6 females (mean age 83.1 ± 3.4 years) and 10 males (mean age 84.2 ± 6.8 years). Classical histological H+E stain was routinely conducted. Subsequently, CD31 antibody (DAKO, Monoclonal Mouse Anti-Human, Clone JC70A) was used to mark vascular epithelium. Monoclonal Mouse Anti-Human Neurofilament Protein (NFP) antibody (DAKO, Clone 2F11) was used to expose the nerves. Moreover, we have conducted arthroscopic visualizing and suturing LM to the torn ACL during routinely performed arthroscopic suturing of the ACL. The dissection process has revealed that LM was present only in 75% of cases. Histological examination confirmed the presence of longitudinal collagen fiber bundles in all samples. Tiny nerves were confirmed by NFP, along the subsynovial layer in all samples. CD-31 immunostain revealed the presence of many vascular vessels along the entire ligament, especially well developed at its distal end. Our study has revealed that LM contains rich vascular network. Thus, it may be a donor for the revascularization process after ACL tear or reconstruction which may improve the recovery. Another great advantage of the LM is the presence of nerves along the subsynovial layer, hopefully they may serve as the source of reinnervation and hence better clinical outcome. Based on our results we believe that seemingly irrelevant LM may be very useful during surgical procedures in the knee region. Suturing LM to the ACL may not only prevent the infrapatellar fat pad from subluxation but also improve the blood flow and reinnervation of the injured ACL. Until now there are only a few studies examining microanatomy of the LM. This basic knowledge may serve as the foundation for surgical procedures. Hopefully our findings may be useful for surgeons while planning surgical procedures or clinicians while diagnosing patients who suffer anterior knee pain.

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

OBJECTIVE

To assess the relationship of the infrapatellar plica (IPP) with femoral trochlear chondrosis (FTC) using radiographs and 3.0-T MRI.

MATERIALS AND METHODS

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.

RESULTS

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%.

CONCLUSION

Presence of the IPP combined with ISR > 1.00 was correlated with FTC.

The ligamentum mucosum: A new classification

The ligamentum mucosum (LM) is a ligamentous structure within the synovial layer of the knee joint capsule. For a long time LM was perceived as the vestigial remnant from the embryological development of the knee. However, last years have shown increased interest in this structure due to its potentially significant clinical role. Fifty-one, 12 females (mean age 83.1 ± 3.4 years) and 39 males (mean age 84.2 ± 6.8 years) fixed in 10% formalin were examined. Upon dissection, the following morphological features of the LM were assessed: the types of LM, morphometric measurement and histological analysis of each type. The LM was present in 66.7% of all examined specimens. Three different types were recognized: Type I (55.9%)-single band with attachment to the intercondylar notch, Type IIa-bifurcated ligament with attachment to the anterior cruciate ligament, Type IIb-bifurcated ligament with both attachments to the intercondylar notch, Type III-double ligament with two independent bands and attachments to the intercondylar notch and to the knee joint capsule. The LM is variable and probably evolutionary changes are the reason. In our study we propose the new clinically useful classification supported by its anatomical and histological characteristics. Type IIa seems to be the most important from the clinical point of view, as it may be responsible for clinical issues and should be paid attention while diagnosing patients suffering from anterior cruciate ligament torn or anterior knee pain.

Embryological approach to the morphology of the ligamentum mucosum of the human knee joint

PURPOSE

The ligamentum mucosum is a ligamentous structure within the synovial layer of the knee joint capsule. It usually arises from the infrapatellar fat pad and is inserted into the intercondylar notch of the femur. In recent years, more attention has been paid to this structure because of its clinical significance. Despite the growing attention, the complex morphology of the ligamentum mucosum has led to many misunderstandings among the scientists and clinicians. Therefore, the main objective of this study was to characterize the morphology of the ligamentum mucosum and its attachment points, classify it, and evaluate its prevalence.

METHODS

Classical anatomical dissection was performed on 70 lower limbs of human fetuses fixed in 10% formalin solution. Morphology was carefully assessed, and morphometric measurements were performed. The types revealed were classified.

RESULTS

The ligamentum mucosum was present in 100% of all 70 specimens examined. Two types were detected. Type I (65.71%) - "cord-like". This type was the most common and is characterized by a single longitudinal ligament. The proximal attachment of the ligamentum mucosum was located in the middle of the infrapatellar fat, and the distal attachment was at the tip of the intercondylar notch. Type II (34.29%) - "vertical septum". This type is less common, but its morphology is much more complex compared to type I. It is wider and thicker than type I. Proximally, it is attached to the infrapatellar fat pad and distally through the entire intercondylar notch down to the anterior surface of the anterior cruciate ligament. It divides the joint cavity into medial and lateral sides.

CONCLUSION

The ligamentum mucosum exhibits high morphologic variability, and the view that it is a vestigial remnant of the embryologic development of the knee should be reconsidered. We have proposed an anatomical classification of its types in human fetuses, which is a valuable addition to existing knowledge and will hopefully change the approach of clinicians and scientists.

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.

Patella-patellar tendon angle decreases in patients with infrapatellar fat pad syndrome and medial patellar plica syndrome

PURPOSE

Infrapatellar fat pad (IPFP) syndrome and medial patellar plica (MPP) syndrome are two recognized causes of anterior knee pain. However, diagnosing these syndromes is challenging without arthroscopic examination. The aim of this study was to evaluate sagittal patellar tilt in patients with IPFP syndrome or MPP syndrome by measuring the patella-patellar tendon angle (PPTA) in affected patients.

METHODS

Eighty-three patients with anterior knee pain who underwent diagnostic arthroscopy that confirmed isolated IPFP or MPP syndrome from 2011 to 2016 were included in this retrospective study. Patients were divided into Group A (IPFP syndrome, n = 44) and Group B (MPP syndrome, n = 39). The control group included 78 patients without knee pathology who underwent magnetic resonance imaging (MRI) of the knee during the study period. Radiographic measurements, including PPTA, IPFP area, patellar height, axial patellar alignment, patellar tilt, sulcus angle, and lateral trochlear inclination, were made on MRI images by two experienced sports medicine orthopedists.

RESULTS

The mean PPTA in each knee-pathology group was significantly smaller than that in the control group (Group A: 137.3° ± 4.9°; Group B: 138.1° ± 3.2°; control group, 141.4° ± 2.9°). There was no significant difference between groups for any other radiographic parameter evaluated.

CONCLUSION

The PPTA was significantly smaller in patients with IPFP syndrome or MPP syndrome than in healthy controls. Therefore, sagittal patellar tilt should be included in the routine evaluation of patients with anterior knee pain. Evaluation of PPTA may help to diagnose IPFP syndrome or MPP syndrome.

LEVEL OF EVIDENCE

Level IV.

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

OBJECTIVE

Nowadays, 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.

METHODS

Retrospective 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.

RESULTS

Some 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.

CONCLUSION

The 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.

Symptomatic medial synovial plica of the knee joint: an underestimated pathology in young patients

INTRODUCTION

To prospectively evaluate the outcome of arthroscopic resection of a symptomatic medial plica in patients under 30 years with evaluating the influence of sports, knee trauma and plica type.

METHODS

35 consecutive patients (38 knees), mean age 16.2 ± 4.7 years (9-26 years), 28 females (73.7%) were prospectively included. Patients with any additional surgical procedures or cartilage lesions > ICRS grade I were excluded. The influence of trauma to the knee, level of sport and the morphologic plica type on the outcome was evaluated in addition to standard knee scores before and 20.1 ± 9.3 months (12-44 months) after surgery.

RESULTS

The Knee Injury and Osteoarthritis Outcome Score improved significantly from 50.2 ± 19.1% (12.5-94.6) to 80.7 ± 15.3% (48.2-100; p < 0.001). The Tegner Activity Scale improved significantly from 2.2 ± 1.5 (0-6) to 4.9 ± 1.7 (3-10; p < 0.001) and the Kujala Anterior Knee Pain Scale improved significantly from 52.6 ± 16.6 (16-86) to 80.7 ± 16.5 (46-100; p < 0.001). The level of pain in the knee decreased from 7.9 ± 2.0 (1-10) to 3.1 ± 2.6 (0-9; p < 0.001) at follow-up on a numeric rating scale (0-10). Neither trauma to the knee, high impact sport, cartilage lesions to the medial femoral condyle nor the plica type or associated ICRS grade I cartilage lesion to the medial femoral condyle had a significant effect on the outcome parameters.

CONCLUSION

Arthroscopic resection of a symptomatic medial plica provides excellent clinical results in young patients. Trauma, high impact sports, ICRS grade I cartilage lesions to the medial femoral condyle or the plica type are not associated with a poorer outcome.

LEVEL OF EVIDENCE

Level IV, prospective case series with no control group.

The biomechanical and morphological characteristics of the ligamentum mucosum and its potential role in anterior knee pain

BACKGROUND

The ligamentum mucosum is composed of dense regular connective tissue and traverses from the distal femur to the infrapatellar fat pad. While the gross and histologic morphology has been studied, there is currently no evidence concerning the biomechanical properties of the ligamentum mucosum and the potential of anterior knee pain. The purpose of this study was to determine the anatomical, mechanical and histological properties of the ligamentum mucosum.

METHODS

Dissections were performed on cadaveric knee specimens (N = 18) and histological analysis (n = 6) was performed to define the anatomical characteristics of the ligamentum mucosum using standard hematoxylin and eosin (H&E), Masson's trichrome, and immunohistochemical methods. Biomechanical testing (n = 5) was conducted to determine the tensile properties of the ligamentum mucosum. The peak load at failure, stiffness, and strain were analyzed.

RESULTS

Sixty-four percent of the knees had a ligamentum mucosum and the histological analysis confirmed it to be composed of dense regular connective tissue. Small peripheral nerves were identified in the junction between the ligamentum mucosum and the fat pad. The average (SD) peak force of failure, stiffness, and strain were 31.9 N (19.0), 5.1 N/mm (3.59), and 0.83 (0.14), respectively.

CONCLUSIONS

The tensile strength and stiffness of the ligamentum mucosum is considerably less than the primary stabilizers of the knee joint. Based on these findings, it is improbable that the ligamentum mucosum has a meaningful effect on the kinematics of the extensor mechanism; perturbations of the tissue and the connected infrapatellar fat pad could potentially play a role in the pathogenesis of anterior knee pain.

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.

A new anterior inferior coronal patellar plica

PURPOSE

To date, four synovial plicae are classically described in the knee. We report a previously undescribed new inferior patellar plica, named "bib-like plica" (BLP, referring to its morphology) related to specific symptoms of atypical recurrent anterior knee pain in the presence of a locked or pseudo-locked knee. We describe this anatomical structure, and assess its clinical relevance in daily practice in terms of clinical pattern and long-term follow-up outcome after arthroscopic excision.

METHODS

We retrospectively reviewed prospectively collected data on 1033 arthroscopic procedures, selecting patients in whom a knee arthroscopy was indicated following recurrent painful episodes of locking or pseudo-locking not explained by traditional imaging or helped by conservative treatment. Visual Analog Scale (VAS), Lysholm knee score, a physical exam and a satisfaction interview were used to evaluate the clinical status at the latest follow-up.

RESULTS

We report 12 patients (8 males, 4 females; mean age 34.2 years) in whom a BLP had been identified at arthroscopy. At a mean follow-up of 13.4 years from its excision, the mean VAS and Lysholm knee score were 9.8 and 100 respectively. In all instances, selective removal of the BLP restored a complete painless functional range of motion documented within 2 months, and confirmed at the latest follow-up. No patient reported locking recurrence or pain, or underwent further surgery, and all were satisfied.

CONCLUSIONS

The BLP, detected in about 1% of knee arthroscopies in our setting, is strongly associated with a recurrent painful locking knee. Arthroscopic removal produces resolution of symptoms.

Substance-P in symptomatic mediopatellar plica as a predictor of patellofemoral pain

The present study aimed to investigate the expression of a neuropeptide of symptomatic mediopatellar plica (MP) to prove that there was a significant correlation between the expression of substance-P (SP) in MP and patellofemoral pain. The specimens of synovial plica were obtained by knee arthroscopy. Semi-quantitative analysis was used to investigate the expression of SP, and compared the innervation density of SP among the three groups: Blank control (asymptomatic plica), positive control (symptomatic plica with other injuries) and experimental (symptomatic plica without other injuries) groups by the paired t-test, one-way analysis of variance and Student-Newman-Keuls test in 60 patients. The expression levels of SP nerve fibers in the superior plica were 24.60±26.17, 117.36±73.62 and 59.06±44.06 in the blank control, positive control and experimental groups, respectively. The density of nerve fibers in medial plica was 23.23±18.41 in the blank control group, 268.00±71.60 in the positive control group and 255.44±87.91 in the experimental group. The density of nerve fibers of MP was higher compared to that of the superior plica. The density was highest in the positive control group, and lowest in the blank control group in MP. There was a close correlation between the density of SP expression and the degree of patellofemoral pain. The SP expression intensity has an important role in the incidence of patellofemoral pain and is responsible for the pathogenesis of symptomatic MP.

Posterior Hoffa's fat pad impingement secondary to a thickened infrapatellar plica: a case report and review of the literature

We report a case of posterior hoffitis in a middle-aged woman with no prior history of significant major trauma. Her symptoms of anterior knee pain and limited extension failed conservative measures. Preoperative magnetic resonance imaging demonstrated a significantly thickened infrapatellar plica tethering Hoffa's fat pad in the anterior interval of the knee. Arthroscopic resection of the infrapatellar plica resulted in complete resolution of symptoms within six months following the surgery.

Diagnostic Differences for Anterior Knee Pain between Sexes in Adolescent Basketball Players

BACKGROUND

The purpose of this study was to determine if there is a sex difference in the prevalence of specific patellofemoral disorders that cause anterior knee pain in adolescent basketball players undergoing pre-participation screening.

METHODS: SETTING

Biomechanical Laboratory.

METHODS: PARTICIPANTS

A total of 810 (688 female and 122 male) basketball players from a single county public school district.

METHODS: MAIN OUTCOME MEASURES

Prior to the start of three consecutive basketball seasons, participants were evaluated for anterior knee pain. Testing consisted of completion of the Anterior Knee Pain Scale. Those with positive findings completed an IKDC form, a standardized history and a physician-administered physical examination.

RESULTS

Anterior knee pain was noted in 410 of 1620 knees (25.3%). 26.6% of female knees and 18.0% of male knees were affected (p<0.05). Patellofemoral dysfunction (PFD) was the most common diagnosis with an overall prevalence of 6.4% (7.3% females; 1.2% males). Less common were Sinding-Larsen-Johanssen disease (SLJ), 4.8% (5.0% females; 3.7% males), Osgood-Schlatter Disease (OSD) 2.5% (2.3% females; 4.1% males); and plica syndrome 2.3% (2.1% females; 3.3% males). The remaining diagnoses (trauma, fat pad syndrome, IT band and pes anserine bursitis) had a combined prevalence of 1.7% (1.9% females; 1.6% males).

CONCLUSIONS

PFD was significantly more common in females (p<0.05). Anterior knee pain was more common in adolescent female basketball players than in adolescent male basketball players.

LEVEL OF EVIDENCE

Descriptive Laboratory Study. Level 1.

Expected prevalence from the differential diagnosis of anterior knee pain in adolescent female athletes during preparticipation screening

CONTEXT

Anterior knee pain is a common disorder in female athletes with an undefined cause. The relative prevalence of specific patellofemoral disorders associated with anterior knee pain in adolescent females remains undetermined.

OBJECTIVE

To determine the prevalence of specific patellofemoral disorders obtained using the differential diagnosis of anterior knee pain in adolescent female athletes during preparticipation screening.

DESIGN

Descriptive epidemiology study.

SETTING

Preparticipation screening evaluations at a county public school district in Kentucky.

PATIENTS OR OTHER PARTICIPANTS

A total of 419 unique middle and high school-aged female athletes.

MAIN OUTCOME MEASURE(S)

Participants were evaluated by physicians for anterior knee pain over 3 consecutive basketball seasons. Given the longitudinal nature of this study, some participants were tested longitudinally over multiple years.

RESULTS

Over the course of 3 basketball seasons, 688 patient evaluations were performed. Of these, 183 (26.6%) were positive for anterior knee pain. A statistically significant difference was noted in the prevalence of anterior knee pain by school level, with 34.4% (n = 67) in high school-aged athletes versus 23.5% (n = 116) in middle school-aged athletes (P < .05). In the 1376 knees evaluated, patellofemoral dysfunction was the most common diagnosis, with an overall prevalence of 7.3% (n = 100). The only diagnosis shown to be statistically different between age levels was Sinding-LarsenJohansson disease or patellar tendinopathy, with 38 cases (9.7%) in high school-aged and 31 (3.1%) in middle school-aged athletes (P < .05).

CONCLUSIONS

Anterior knee pain was present in 26.6% of the adolescent female athletes screened over 3 years. Symptoms of anterior knee pain likely persist after middle school-aged onset and reach peak prevalence during the high school years.

Medial plica syndrome: a review of the literature

Knee pain is a very common complaint seen in the clinical setting. A torn medial meniscus, osteochondral defects, inflammation, or an irritated medial plica are some of the most common causes of medial knee pain. Plicae are synovial invaginations that are believed to be remnants of the embryological development of the knee. They have a potential to become inflamed and symptomatic. Diagnosis of medial plica syndrome involves physical exam and imaging studies, but the current gold standard is arthroscopy and therefore a definitive diagnosis cannot be made until surgery. As such, medial plicae are the most commonly missed diagnoses in the knee as it is purely a clinical diagnosis. Medial plica syndrome can be treated with physiotherapy, corticosteroid injections, or surgery. Overall, good outcomes have been seen following diagnosis and treatment of medial plica syndrome, with patients returning to their preferred levels of activity. This article reviews the topic of medial plica syndrome.

Loss of a condyle of the femur or tibia following septic arthritis in infancy: problems of management and testing of a hypothesis of pathogenesis

PURPOSE

The study was undertaken to: (1) describe the characteristic radiological features and problems of management of the loss of one condyle of the femur or tibia following septic arthritis of the knee in infancy and (2) test a hypothesis of the cause of the loss of a single condyle.

METHODS

Radiographs of eight children with the loss of one condyle of the femur or the tibia following septic arthritis in infancy were reviewed. The course and outcome in two of these children who underwent reconstructive operations were studied. The knees of 35 stillborn foetuses were dissected to determine if the presence of synovial septae could account for the isolated loss of one condyle following infection.

RESULTS

All eight cases showed characteristic features of loss of half the epiphysis, the underlying physis and part of the adjacent metaphysis; the other condyle was totally spared. The two children who underwent elaborate reconstructive procedures had poor outcomes at skeletal maturity, despite a series of additional operations. The foetal cadaveric study showed that complete infrapatellar synovial septae are present in some foetuses approaching 40 weeks of gestation.

CONCLUSIONS

The pattern of loss of a femoral or tibial condyle following septic arthritis is consistent with total preservation of the other condyle. The outcome of surgical reconstruction of the missing condyle is poor. The presence of a complete synovial septum could result in the localisation of infection to one half of the joint, with the destruction of one condyle.

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.

Review article: Plica syndrome of the knee

Plica syndrome is a pathological condition secondary to inflammation. Plicae around the knee are common and generally asymptomatic. They often are misdiagnosed. The morphology of knee plicae varies; mediopatellar plicae are the most common cause of the plicae syndrome. An intermittent dull pain is the most common symptom. Diagnosis is made by exclusion. Ultrasonography is useful; arthroscopy is the gold standard. Arthroscopic removal of the plica may be necessary when conservative treatment for up to 6 months fails.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Synovial plicae around the knee

Synovial plicae around the knee are a relatively common occurrence but one that is rarely responsible for symptoms. The Plica syndrome has been well described but controversy still exists regarding its diagnosis and treatment. We have reviewed and studied the published literature both past and present in detail regarding synovial plicae around the knee to provide a comprehensive and up-to-date review on the subject. The aim is to outline previous significant research into the embryology and pathology of synovial plicae as well as providing a review of the current thinking on treatment options available for the different synovial plicae with reference to the evidence available.

Anterior knee pain

Anterior knee pain is a common complain in all ages athletes. It may be caused by a large variety of injuries. There is a continuum of diagnoses and most of the disorders are closely related. Repeated minor trauma and overuse play an important role for the development of lesions in Hoffa's pad, extensor mechanism, lateral and medial restrain structures or cartilage surface, however usually an increase or change of activity is referred. Although the direct relation of cartilage lesions, especially chondral, and pain is a subject of debate these lesions may be responsible of early osteoarthrosis and can determine athlete's prognosis. The anatomy and biomechanics of patellofemoral joint is complex and symptoms are often unspecific. Transient patellar dislocation has MR distinct features that provide evidence of prior dislocation and rules our complication. However, anterior knee pain more often is related to overuse and repeated minor trauma. Patella and quadriceps tendon have been also implicated in anterior knee pain, as well as lateral or medial restraint structures and Hoffa's pad. US and MR are excellent tools for the diagnosis of superficial tendons, the advantage of MR is that permits to rule out other sources of intraarticular derangements. Due to the complex anatomy and biomechanic of patellofemoral joint maltracking is not fully understood; plain films and CT allow the study of malalignment, new CT and MR kinematic studies have promising results but further studies are needed. Our purpose here is to describe how imaging techniques can be helpful in precisely defining the origin of the patient's complaint and thus improve understanding and management of these injuries.