Horn Of Meniscus Research Articles

Meniscus transplantation: preoperative planning.

Precise preoperative planning is mandatory to obtain good results of meniscus transplantation. Any pathology in addition to the missing meniscus should be detected, including malalignment, and ligament instability. A full status of the changes in the cartilage should be made. It is unknown how precisely the donor meniscus needs to fit the size of the original meniscus to allow healing and regeneration. The effect of incongruency and wrong insertion of the meniscal horns has been investigated in an animal experiment. The incongruous grafts did not entirely avoid chondromalacia after meniscectomy, but provided some chondroprotective effect. A wrong bony insertion of the meniscal horns leads to even more serious chondral damage than meniscectomy.

How three methods for fixing a medial meniscal autograft affect tibial contact mechanics.

We evaluated three methods for fixing a medial meniscal autograft to determine which method restored tibial contact mechanics closest to normal. The contact mechanics (maximum pressure, mean pressure, contact area, and location of the center of maximum pressure) of the medial tibial articular surface were determined using pressure-sensitive film while knee specimens were loaded in compression to 1000 N at 0 degree, 15 degrees, 30 degrees, and 45 degrees of flexion. Pressure was measured for the intact knee, the knee after meniscectomy, and the knee with the original meniscus removed and reimplanted as an autograft using three different fixation methods. The contact mechanics of the autograft reinserted with bone plug fixation were closest to normal; however, the maximum pressure was significantly greater than in the intact knee. Adding peripheral sutures neither improved nor worsened the contact mechanics. Fixation with sutures only did not restore normal contact mechanics. We concluded that medial meniscal transplantation requires anatomic fixation of bone plugs attached to the anterior and posterior horns to restore contact mechanics closest to normal. Fixation of the meniscal horns with sutures alone cannot be recommended.

An Anatomic Evaluation of T-Fix Suture Device Placement for Arthroscopic All-Inside Meniscal Repair

Summary: This investigation documented the locations of endoscopically applied T-Fix suture devices (Acufex Microsurgical, Mansfield, MA) placed in six fresh-frozen cadaveric knees (age, 60 to 72 years) in relationship to the joint capsule, and adjacent neurovascular and musculotendinous structures. Five T-Fix devices were placed in the posterior meniscal regions at approximately 20° intervals. Gross dissection enabled T-Fix bar and suture placement identification. Fifty total devices were placed (23 medially and 27 laterally). Lateral: None of the devices penetrated more superficially than the deepest capsular layer (layer III). Six of the 27 devices placed at the posterior horn of the lateral meniscus pierced the popliteus tendon. None of the bars pierced the lateral collateral ligament (layer III). All devices placed at the posterolateral knee were outside the arcuate ligament (layer III) but inside the fabellofibular ligament (layer II). Medial: Seven of the 23 devices pierced the deep medial collateral ligament (MCL, layer III), and 4 pierced the superficial MCL (layer II). Three devices pierced the sartorius tendon (layer I) and one pierced the gracilis tendon (layer II). None of the medial devices created a plicating effect on the posterior capsule. None of the devices were placed near neurovascular structures. Devices placed within the posterior meniscal horns had a ≥1.5-cm buffer zone from the popliteal neurovascular bundle. Most bars (36 of 50) were anchored to the capsular layer (layer III) after piercing the meniscocapsular junction (layer II). T-Fix devices simulating arthroscopic all-inside meniscal repair provided well-positioned, solid suture anchorage through the junction with no neurovascular involvement. Care needs to be taken when placing lateral (popliteus muscle) and medial (gracilis, sartorius tendons and superficial MCL) devices to avoid possible soft tissue tenodesis. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 3 (April), 1999: pp 275–280

The Radiographic Position of Medial and Lateral Meniscal Horns as a Basis for Meniscal Reconstruction

Summary: This investigation attempted to determine the radiographic position of human meniscal horn bony insertion sites. This information would prove vital for anatomically correct osseous tunnel placement necessary for the restoration of a functional meniscus after reconstructive surgery. The native bony insertion sites of the medial and lateral meniscus in 13 fresh-frozen human cadaver knees were radiographically examined. After insertion site outline with 22-gauge fine wire, anteroposterior and lateral radiographs were obtained. Radiographic landmarks were then described in detail. Each meniscal horn was found to have a distinct bony insertion site with characteristic and consistent radiographic landmarks defining its margins. Using an arthroscopic guide, 3/32-inch fine wires were drilled into the center of the lateral (5 specimens) and medial (5 specimens) meniscal horns to validate these locations and to establish the clinical usefulness of these measures. Improved understanding of meniscal horn insertion site locations should improve osseous tunnel placements during meniscal transplantation. In the presence of a properly sized allograft, anatomically correct tunnel placement increases the liklihood of restoring normal meniscal function.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 2 (March), 1999: pp 147–154

Meniscal movement. An in-vivo study using dynamic MRI.

We present the first study in vivo of meniscal movement in normal knees under load. Using an open MR scanner, allowing imaging in physiological positions in near to real-time, 16 young footballers were scanned moving from full extension to 90 degrees flexion in the sagittal and coronal planes. Excursion of the meniscal horns, radial displacement and meniscal height were measured. On weight-bearing, the anterior horn of the medial meniscus moves through a mean of 7.1 mm and the posterior horn through 3.9 mm, with 3.6 mm of mediolateral radial displacement. The height of the anterior horn increases by 2.6 mm and that of the posterior horn by 2.0 mm. The anterior horn of the lateral meniscus moves 9.5 mm and the posterior horn 5.6 mm, with 3.7 mm of radial displacement. The height of the anterior horn increases by 4.0 mm, and that of the posterior horn by 2.4 mm. In non-weight-bearing, the anterior horn of the medial meniscus moves 5.4 mm and the posterior horn 3.8 mm, with 3.3 mm of radial displacement. The anterior horn of the lateral meniscus moves 6.3 mm, and the posterior horn 4.0 mm, with 3.4 mm of radial displacement. The most significant differences between weight-bearing and non-weight-bearing were the movement and vertical height of the anterior horn of the lateral meniscus.

Meniscal movement

We present the first study in vivo of meniscal movement in normal knees under load. Using an open MR scanner, allowing imaging in physiological positions in near to real-time, 16 young footballers were scanned moving from full extension to 90° flexion in the sagittal and coronal planes. Excursion of the meniscal horns, radial displacement and meniscal height were measured. On weight-bearing, the anterior horn of the medial meniscus moves through a mean of 7.1 mm and the posterior horn through 3.9 mm, with 3.6 mm of mediolateral radial displacement. The height of the anterior horn increases by 2.6 mm and that of the posterior horn by 2.0 mm. The anterior horn of the lateral meniscus moves 9.5 mm and the posterior horn 5.6 mm, with 3.7 mm of radial displacement. The height of the anterior horn increases by 4.0 mm, and that of the posterior horn by 2.4 mm. In non-weight-bearing, the anterior horn of the medial meniscus moves 5.4 mm and the posterior horn 3.8 mm, with 3.3 mm of radial displacement. The anterior horn of the lateral meniscus moves 6.3 mm, and the posterior horn 4.0 mm, with 3.4 mm of radial displacement. The most significant differences between weight-bearing and non-weight-bearing were the movement and vertical height of the anterior horn of the lateral meniscus.

The menisci of the knee joint. Anatomical and functional characteristics, and a rationale for clinical treatment.

The menisci and their insertions into bone (entheses) represent a functional unit. Thanks to their firm entheses, the menisci are able to distribute loads and therefore reduce the stresses on the tibia, a function which is regarded essential for cartilage protection and prevention of osteoarthrosis. The tissue of the hypocellular meniscal body consists mainly of water and a dense elaborate type I collagen network with a predominantly circumferential alignment. The content of different collagens, proteoglycans and nonproteoglycan proteins shows significant regional variations probably reflecting functional adaptation. The meniscal horns are attached via meniscal insertional ligaments mainly to tibial bone. At the enthesis, the fibres of the insertional ligaments attach to bone via uncalcified and calcified fibrocartilages. This anatomical configuration of gradual transition from soft to hard tissue, which is identical to other ligament entheses, is certainly essential for normal mechanical function and probably protects this vulnerable transition between 2 biomechanically different tissues from failure. Clinical treatment of meniscal tears needs to be based on these special anatomical and functional characteristics. Partial meniscectomy will preserve some of the load distribution function of the meniscus only when the meniscal body enthesis entity is preserved. Repair of peripheral longitudinal tears will heal and probably preserve the load distribution function of the meniscus, whereas radial tears through the whole meniscal periphery or more central and complex tears may be induced to heal, but probably do not preserve the load distribution function. There is no proof that replacement of the meniscus with an allograft can reestablish some of the important meniscal functions, and thereby prevent or reduce the development of osteoarthrosis which is common after meniscectomy. After implantation, major problems are the remodelling of the graft to inferior structural, biochemical and mechanical properties and its insufficient fixation to bone which fails to duplicate a normal anatomical configuration and therefore a functional meniscal enthesis.

Insertion-site anatomy of the human menisci: Gross, arthroscopic, and topographical anatomy as a basis for meniscal transplantation

A cadaveric study was performed to determine the insertion-site anatomy of the human menisci, their topographical relationships to adjacent intra-articular structures, and which arthroscopic portal provides for optimal visualization of each insertion site. Fifteen fresh-frozen cadaver knees were studied (ages 48 to 63 years). Ten knees underwent arthroscopy using four standard arthroscopic portals. Visualization and placement of an arthroscopic guide over each meniscal horn insertion site was attempted through the four arthroscopic portals. Guide wires were drilled to mark horn insertions followed by a gross dissection to evaluate accuracy of the guide wire gross dissection to evaluate accuracy of the guide wire placement and to isolate meniscal horn insertion sites. Insertion sites were outlined and evaluated for size and topographical relationships to other intra-articular structures. Five additional knees were dissected free of all soft tissues except the tibial insertions of the meniscal roots and anterior cruciate ligament/posterior cruciate ligament. Each tibia was mounted in a jig and a digitizing system was used to record coordinates of points along the outline of each bony meniscal horn insertion site, the ACL tibial insertion, and the articular surface of each tibial plateau. The x, y, z coordinates for each point were calculated and loaded into a computer program allowing for surface area determination and computer-generated topographical maps to assess relative position of each specific insertion site. Placement of the arthroscope in the anterolateral portal allows optimal visualization and guide wire placement for both lateral meniscal horn insertion sites. Medial meniscal anterior and posterior horn insertion sites are best visualized with the arthroscope in the anteromedial and posteromedial portals respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Meniscal reconstruction: Present and future

Our treatment of meniscal pathology has changed dramatically over the last 30 years. What began with totalmeniscectomy is now ending with meniscal replacement. Basic science investigation of the preservation, healing, and function of meniscal replacement substitutes has shown that meniscal reconstruction is feasible and successful by various limited criteria. Clinical studies seem to suggest that the ideal candidate may be a young individual with early cartilage wear (grade I or II) who is ligamentously stable without articular incongruity. Surgical techniques using fresh-frozen and cryopreserved meniscal allograft have included open and arthroscopically assisted insertion techniques. Anchoring of the meniscal horns has been described using soft tissue, bone plugs or blocks, or a bony bridge connecting the anterior and posterior horns. Attempting to draw conclusions by comparing the results of the few preliminary studies that have been published is exceptionally difficult. Differences in patient selection, concomitant procedures, meniscal substitute selection, surgical technique, graft fixation, rehabilitation, and length of follow-up make this nearly impossible. Standardized methods for patient selection, operative technique, rehabilitation, and length of follow-up need to be determined to further define meniscal replacement techniques. It remains cautiously optimistic that meniscal replacement remains a treatment for the postmeniscectomy knee.

The menisco-femoral ligaments.

The menisco-femoral ligaments were studied in 60 knees from 30 dissecting room cadavers. The anterior horns of the menisci were attached to the intercondylar area of the femur by discrete antero-medial or antero-lateral menisco-femoral ligaments, separate from the anterior cruciate ligament, in 15% of knees for each meniscus, more frequently than previously appreciated; these anterior horn ligaments may exacerbate a meniscal tear. The posterior horn of the lateral meniscus was connected with the intercondylar area of the femur in 100% of knees. In 93% of knees a ligament ran behind the posterior cruciate ligament while in 33% of knees a ligament ran in front of the posterior cruciate ligament. We propose renaming these the pre-cruciate postero-lateral menisco-femoral ligament and post-cruciate postero-lateral menisco-femoral ligament, respectively, to avoid confusion with the ligaments of the anterior horns. The menisco-femoral ligaments may function in controlling movement of the menisci, especially during rotation of the knee. The posterior horn of the medial meniscus has no direct femoral attachment and this may be a factor in the increased risk of injury to this meniscus.

Vertical tears of the cranial horn of the meniscus and its cranial ligament in the equine femorotibial joint: 7 cases and their treatment by arthroscopic surgery

Five horses with a vertical tear in the cranial horn and cranial ligament of the medial meniscus and 2 horses with a similar injury in the lateral meniscus were diagnosed from a series of 126 horses which were examined arthroscopically for stifle lameness. All the lesions had similar characteristics. The tear was about 1 cm from the axial border of the meniscus and its ligament and, in all but one case in which it was incomplete, much of the torn tissue was loosely attached in the axial part of the joint from where it was removed. The remaining meniscus, abaxial to the tear, was displaced cranially and abaxially and its torn edges were debrided. Radiographically, 6 cases had proliferative new bone on the cranial aspect of the intercondylar eminence of the tibia and 3 had calcified soft tissue densities in the cranial, medial or lateral femorotibial joint. Following surgery and a 6 month period of rest and controlled exercise, 3 horses returned to full competition work, one was usable for hacking, 2 are convalescing and one is lame after one year. It is postulated that this could be a characteristic meniscal injury in horses which can benefit from arthroscopic surgery. Better techniques for accessing the body and caudal pole of the menisci are needed if a more complete diagnosis and treatment of meniscal injuries are to be achieved.

Meniscal reconstruction using allograft tissue: An arthroscopic technique

The treatment of meniscal pathology has changed dramatically over the last decade. This change in treatment has been brought about by our increased knowledge of the functions of the human meniscus: force transmission, increase contact area, decrease contact stress, shock absorption, joint lubrication, nutrition of chondrocytes, and stabilization. Meniscal transplantation has been developed in an attempt to interrupt or retard the progressive joint deterioration that develops in the postmeniscectomy knee. The author's arthroscopically assisted technique for meniscal reconstruction using fresh frozen allograft tissue without disruption of the extensor mechanism or collateral ligaments is described. This technique emphasizes visualization of specific landmarks for each meniscal horn insertion site with creation of osseous tunnels at these corresponding sites to allow for anatomic placement of the meniscal inplant. Only if normal anatomy and kinematics is established can one assume that the transplanted meniscus will provide a beneficial function. The author's believe that the operation should be limited to a select group of individuals who meet specific inclusion criteria in study groups and investigational protocols until long-term results are determined.

The flipped meniscus sign.

Meniscal fragments may be difficult to detect on magnetic resonance (MR) imaging and yet are clinically significant. This paper describes and illustrates the MR appearance of an easily overlooked meniscal fragment. Ten knees, each appearing to show an abnormally large anterior meniscal horn (8 mm or more in height) were prospectively identified on MR images. In each case demonstrable large tears of the ipsilateral posterior horns were present (same meniscus as had large anterior horns). The lateral meniscus was involved in nine cases and the medial in one. Two of the ten patients imaged had surgically proven bucket-handle meniscal tears as well as meniscal fragments overlying the ipsilateral anterior horn. In one case previous MR imaging at our institution had demonstrated the affected anterior horn to be of normal caliber. The striking MR appearance of an abnormally enlarged anterior meniscal horn in association with a tear of the ipsilateral posterior horn suggests the presence of a meniscal fragment or of a posteriorly detached bucket-handle tear of the posterior horn of the meniscus.

Surgical technique of meniscal replacement

Meniscal replacement by allograft and prosthesis is under laboratory and investigational clinical practice. In order to succeed, a replacement must duplicate the exact mechanical function of the original meniscal cartilage. The technique of replacement described in this article permits minimal disruption of the joint tissues, accurate placement of the meniscal horns, and secure fixation of the meniscal synovial junction.

Do asymptomatic marathon runners have an increased prevalence of meniscal abnormalities? An MR study of the knee in 23 volunteers.

Excessive repetitive musculoskeletal loads and stresses associated with intense physical activity may lead to deterioration of the menisci of the knee. Therefore, MR imaging was performed on the knees of 23 asymptomatic marathon runners (eight men, 15 women; average age, 40 years; average number of years training, 10; average training distance per week, 41 miles) to determine the prevalence of meniscal signal abnormalities. None of the runners had previous knee injuries or surgery and each of them regularly competes in 26-mile, 50-mile, or 100-mile marathon races. T1-weighted coronal MR images and proton density-weighted and T2-weighted sagittal images were obtained with a 1.5-T MR system and a transmit/receive extremity coil. The medial and lateral menisci were divided into four portions, or horns, and a total of 92 horns were evaluated (i.e., four horns per knee: medial posterior, medial anterior, lateral posterior, and lateral anterior). Two meniscal horns (2%) had grade 3 signal (grade 3 indicates a meniscal tear), 12 (13%) had grade 2 signal, 29 (32%) had grade 1 signal (grades 1 and 2 are indicative of meniscal degeneration), and 49 (53%) had grade 0 signal (grade 0 is normal). Overall, the prevalence of meniscal tears was 9% (two meniscal tears found in 23 runners). This is lower than the prevalence of MR signal abnormalities indicative of meniscal tears reported for asymptomatic, nonrunner athletes (20% of 20 athletes) and for asymptomatic nonathletes (16% of 74 subjects). Fifty-three percent of the meniscal horns of the nonrunner athletes had grade 1 or 2 signal, indicative of meniscal degeneration. Our results indicate that the prevalence of meniscal tears in marathon runners is no higher than the prevalence reported for sedentary persons, and the runners have the same amount of meniscal degeneration as do nonrunner athletes.

A suture “retractor”: A technical aid for bucket-handle meniscal resections

Meniscal repair, healing, and survival have been demonstrated in the literature. Meniscal preservation is, however, not always possible. We present a technique that may aid the surgeon in difficult bucket handle resections by stabilizing a portion of the meniscus with a “suture retractor” prior to resecting either a posterior or anterior meniscal horn. This technique may also be modified to prepare the inner rim when one is performing meniscal repair.

Meniscal abnormalities in the asymptomatic population at MR imaging.

Two hundred eighty meniscal horns in 64 asymptomatic volunteers in the 2nd to 8th decades of life were analyzed for meniscal abnormalities. Grade 1, 2, and 3 changes were present in essentially all decades. There was at least a 25% prevalence of meniscal signal abnormalities as early as the 2nd decade. The prevalence of meniscal abnormalities increased sharply with age. The prevalence of all signal abnormalities correlated with age, grade 2 changes having the highest correlation coefficient (+.88). The correlation coefficient for grades 1 and 3 changes were +.60 and +.71, respectively. The posterior horn of the medial meniscus had a significantly higher (P less than .02) prevalence of abnormalities than did the other meniscal locations. There was no significant correlation between subject weight or sex and meniscal signal. The authors conclude that there is a baseline prevalence of meniscal signal in the asymptomatic population.

Meniscal tears: the effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee. A preliminary report.

The role of the meniscus in load transmission across the knee has long been a subject of debate. In this study, we examined the biomechanical consequences of the operative treatments for bucket-handle and peripheral meniscal tears. Contact areas and instantaneous intraarticular pressure distributions were measured in two groups of human cadaver knees. In Group I, consisting of four knees, we created a bucket-handle tear involving the inner one-third of the meniscus, followed by partial, and then total meniscectomy. Knees were tested in an Instron testing machine after each procedure, using a 400 pound load at 0 degrees or 30 degrees flexion. Contact areas and local stresses were measured using Prescale, a pressure-sensitive film. After partial meniscectomy, contact areas decreased approximately 10%, and peak local contact stresses (PLCS) increased approximately 65%. After total meniscectomy, contact areas decreased approximately 75%, and PLCS increased approximately 235%. In Group II, consisting of three additional knees, we created a 2 cm peripheral tear of the posterior meniscal horn, followed by open repair, arthroscopic repair, segmental, and then total meniscectomy. Repair of the tear was accomplished with either vertically placed sutures by an open technique or horizontally placed sutures by an arthroscopic technique. Knees were tested in the neutral position in the Instron machine and contact areas and local stresses measured using Prescale. PLCSs and contact areas were found to be the same using either repair technique. There was, however, a 110% increase in PLCS after segmental meniscectomy of that portion of the meniscus involved in the peripheral tear.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional biochemical and morphological characteristics of rat knee meniscus

1. 1. The biochemical and morphological characteristics of the anterior and posterior regions of the rat knee meniscus were studied. 2. 2. The anterior meniscal horn was thicker and contained a lower concentration of DNA, hydroxyproline, and uronic acid as compared to the posterior region. The calcium concentration in the anterior region, however, was significantly greater than the calcium concentration in the posterior horn. 3. 3. Presence of a significant concentration of calcium in the normal rat knee meniscus is unique to rats and uncommon in other mammalian species.

The structure and innervation of cat knee menisci, and their relation to a "sensory hypothesis" of meniscal function.

Previous work on dog knee menisci demonstrated structural differences between the meniscal horns and the meniscal bodies (O'Connor, '76). Of particular interest was the observation that the meniscal horns possessed an abundant blood and nerve supply, while the meniscal bodies did not. The presence of nerves in the meniscal horns prompted the speculation that menisci might perform a sensory function. The present study was undertaken in order to establish whether or not similar regional differences existed in cat knee menisci, structures previously believed to lack a corpuscular mechanoreceptor system (Freeman and Wyke, '67). Differences between the meniscal horns and meniscal bodies similar to those reported in the dog were found to characterize cat knee menisci. In particular, the meniscal horns possessed a rich neurovascular supply, while the meniscal bodies did not. Most important, at least two morphologically different mechano-receptors were identified in the meniscal horns, but none were identified in the meniscal bodies.