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At least 19 recordsLinked to original sources

Sonographic appearances of meniscal cysts.

PURPOSE: This study was conducted to define the sonographic appearances of cysts of the tibial menisci. METHODS: Thirteen cases of meniscal cyst, proven by magnetic resonance imaging (MRI), were assessed using high-resolution sonography, and results of the 2 imaging modalities were correlated. RESULTS: Seven meniscal cysts were lateral to the joint line, and 6 were located medially. MRI showed all 13 cysts to be associated with a tear of the adjoining meniscus. On sonograms, cyst size varied from 9 to 56 mm. Echotexture varied from uniformly hypoechoic or hypoechoic with echogenic septa to heterogeneously hyperechoic. Septated cysts were demonstrated by MRI and sonography. CONCLUSIONS: Because of their diverse echo patterns, meniscal cysts may be easily mistaken for soft-tissue tumors, ganglions, or other lesions, which may result in surgery being inappropriately recommended. This is particularly true in the case of echogenic cysts. The cardinal sonographic characteristic of a meniscal cyst is its continuity with the meniscus, not its echotexture.

Adult↗

Case report: acute joint destabilization in the equine demonstrating early pathology in osteoarthritis.

A case of acute destabilization of the right stifle joint associated with rupture of the anterior cruciate ligament and avulsion fracture of the tibial spine in a horse is reported. The diagnosis was obtained by scintigraphy and radiography. Post mortem investigations 6 weeks after injury demonstrated fibrillation of surface cartilage in regions unprotected by tibial menisci. No pathological change was demonstrated in the subchondral bone of the tibia in regions associated with loss of cartilage integrity.

Animals↗

Quantitation of articular surface topography and cartilage thickness in knee joints using stereophotogrammetry.

An analytical stereophotogrammetry (SPG) technique has been developed based upon some of the pioneering work of Selvik [Ph.D. thesis, University of Lund, Sweden (1974)] and Huiskes and coworkers [J. Biomechanics 18, 559-570 (1985)], and represents a fundamental step in the construction of biomechanical models of diarthrodial joints. Using this technique, the precise three-dimensional topography of the cartilage surfaces of various diarthrodial joints has been obtained. The system presented in this paper delivers an accuracy of 90 microns in the least favorable conditions with 95% coverage using the same calibration method as Huiskes et al. (1985). In addition, a method has been developed, using SPG, to quantitatively map the cartilage thickness over the entire articular surface of a joint with a precision of 134 microns (95% coverage). In the present study, our SPG system has been used to quantify the topography, including surface area, of the articular surfaces of the patella, distal femur, tibial plateau, and menisci of the human knee. Furthermore, examples of cartilage thickness maps and corresponding thickness data including coefficient of variation, minimum, maximum, and mean cartilage thickness are also provided for the cartilage surfaces of the knee. These maps illustrate significant variations over the joint surfaces which are important in the determination of the stresses and strains within the cartilage during diarthrodial joint function. In addition, these cartilage surface topographies and thickness data are essential for the development of anatomically accurate finite element models of diarthrodial joints.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

The effect of tibial lengthening using the Ilizarov method on the cartilage and the menisci of the knee joint.

In order to investigate possible acute damage to the knee joint cartilage and the menisci during tibial lengthening, sixteen young beagle dogs underwent 30% lengthening of the right tibia of 2.5 cm by callus distraction at a distraction rate of twice 0.5 mm per day. A further four dogs comprised the control group with fixator and osteotomy but without lengthening. After a distraction period of 25 days half the dogs were killed (group A) while the other half (eight dogs with limb lengthening and two dogs without) were killed after a further period of 25 days (group B). At the end of the study, the menisci were removed together with three cartilage-bone cylinders from both femoral condyles from the weight-bearing zones as well as from the corresponding tibial condyles. Serial sections from the menisci were stained with haematoxylin and eosin (H&E) and Elastica van Gieson. Sections of the cartilage-bone cylinders were stained with H&E and safranin-O. Cartilage thickness was measured and the glycosaminoglycan content of the joint cartilage was determined using microspectrophotometry. None of the histological preparations obtained from the untreated and distracted sides showed any signs of damage to the cartilage or to the menisci. There were no significant differences between cartilage thickness and proteoglycan content of the untreated side and the lengthened side. Thus, tibial lengthening using the llizarov method does not appear to cause acute damage to the cartilage of the knee joint or to the menisci.

Animals↗

3D finite element model of meniscectomy: changes in joint contact behavior.

The goal of this study is to quantify changes in knee joint contact behavior following varying degrees of the medial partial meniscectomy. A previously validated 3D finite element model was used to simulate 11 different meniscectomies. The accompanying changes in the contact pressure on the superior surface of the menisci and tibial plateau were quantified as was the axial strain in the menisci and articular cartilage. The percentage of medial meniscus removed was linearly correlated with maximum contact pressure, mean contact pressure, and contact area. The lateral hemi-joint was minimally affected by the simulated medial meniscectomies. The location of maximum strain and location of maximum contact pressure did not change with varying degrees of partial medial meniscectomy. When 60% of the medial meniscus was removed, contact pressures increased 65% on the remaining medial meniscus and 55% on the medial tibial plateau. These data will be helpful for assessing potential complications with the surgical treatment of meniscal tears. Additionally, these data provide insight into the role of mechanical loading in the etiology of post-meniscectomy osteoarthritis.

Arthroplasty↗

Proximal superomedial portal in arthroscopy of the knee.

The proximal superomedial portal is placed 4 cm proximal to and in line with the medial edge of the patella. From this position, a 30 degrees arthroscope approaches the midline at a 30 degrees angle providing a "straight on" view of the patellofemoral joint. Passing the scope down the patellofemoral joint allows visualization of the anterior horns of both menisci, the tibial attachment of the anterior cruciate ligament, and the anterior fat pad, but the view on the monitor is upside down. To correct the orientation, the television camera is turned upside down. Both anterior portals are available for instrumentation. Both gutters, including the periphery of both menisci, can be fully viewed from the proximal portal. The menisci appear vertically oriented on the monitor, and the television camera is rotated 90 degrees to provide the usual horizontal orientation. The routine use of this portal is facilitated by using a cannula system, so that the cannula used initially for inflow-outflow irrigation remains in place and the scope is passed through it for viewing.

Arthroscopy↗

The effects of hyaluronan on the meniscus and on the articular cartilage after partial meniscectomy.

The effect of hyaluronan (molecular weight = 8 x 10(5)) on the meniscus and on the articular cartilage was assessed after partial meniscectomy in a rabbit model. On gross examination, remodeled meniscus appeared as newly synthesized translucent tissue, and was seen in both vehicle- and hyaluronan-treated menisci. Histologically, safranin O staining revealed the strong presence of glycosaminoglycans in the newly remodeled tissue, and polarized light demonstrated the absence of mature collagen architecture. Hydration of the hyaluronan-treated menisci was significantly less than that of the vehicle-treated menisci, and the reducible collagen cross-link dihydroxylysinonorleucine was significantly increased in the hyaluronan-treated menisci compared with the vehicle-treated menisci, indicative of a greater degree of collagen remodeling. In situ hybridization of vehicle- and hyaluronan-treated menisci revealed a high level of type I procollagen mRNA expression and minor expressions of types II and III mRNA. Expression of the type I collagen gene appeared to be more pronounced in the hyaluronan-treated menisci than in the vehicle-treated menisci. The tibial plateaus revealed mild cartilage fibrillation after partial meniscectomy. A statistically significant difference between vehicle- and hyaluronan-treated cartilage was not demonstrated in the present study because of the slow development (i.e., 12 weeks) of osteoarthritis after partial meniscectomy in the rabbit model. These results suggest that in the rabbit model, hyaluronan enhances collagen remodeling and inhibits meniscal swelling after partial meniscectomy in the avascular region.

Analysis of Variance↗

The long-term effects of hyaluronan during development of osteoarthritis following partial meniscectomy in a rabbit model.

OBJECTIVE: The long-term effect of hyaluronan (HA) on meniscus remodeling and articular cartilage preservation was assessed during the development of osteoarthritis following partial meniscectomy in a rabbit model. DESIGN: Approximately 60% of the region of each medial meniscus of 20 rabbit knees was excised bilaterally. The left knee joint was treated with five weekly intraarticular injections of 0.3 ml of HA, beginning 1 week after surgery. The right control knee was injected with PBS on the same schedule. Six months after surgery, animals were killed and the medial menisci and tibial articular cartilage were evaluated morphologically, histologically and biochemically. RESULTS: Meniscal regeneration was observed as newly synthesized translucent tissue, and image analysis revealed that the amount of this tissue was significantly greater in the HA-treated menisci than in the vehicle-treated menisci. Safranin-O staining and image analysis revealed the increased presence of glycosaminoglycans in the HA-treated menisci relative to vehicle-treated menisci while vascularity and biochemical parameters (hydration, total GAGs and reducible collagen crosslinks) were statistically similar in HA- and vehicle-treated menisci. Gross morphologic grading with India ink revealed a trend for less deterioration of tibial articular cartilage in the HA group (P=0.09) while Mankin's score of the HA-treated tibial articular cartilage was marginally lower than that of the vehicle group (P=0.06). Biochemical assessments showed a trend for higher total GAGs concentration in the HA-treated articular cartilage when compared to the vehicle treatment group (P=0.06). CONCLUSION: The present study has demonstrated that following partial meniscectomy, treatment with hyaluronan can enhance meniscal regeneration and may inhibit articular cartilage degeneration as long as six months post surgery.

Animals↗

All-inside repair is an effective treatment for medial meniscus posterior root tears: a systematic review and meta-analysis of biomechanical and clinical evidence.

BACKGROUND: Medial meniscus posterior root tears (MMPRTs) reproduce the biomechanics of subtotal meniscectomy. Repair is favored, but the role of all-inside repair (AR) remains unclear relative to transtibial pull-out (TP). This study aimed to review the biomechanical and clinical evidence on AR for MMPRTs. METHODS: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO). MEDLINE, Embase, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched. Outcomes included patient-reported outcome measures (PROMs), magnetic resonance imaging (MRI), and biomechanical performance. When available, random-effects meta-analysis was performed. RESULTS: Thirteen studies were included. AR restored contact mechanics and showed load to failure comparable to TP, with lower stiffness. Meta-analysis showed lower conversion to total knee arthroplasty with AR versus non-repair (RR 0.18, 95% CI 0.05-0.58), and no significant PROM differences between AR and TP. CONCLUSIONS: AR showed favorable biomechanical properties and improved outcomes versus non-repair. Compared with TP, no significant clinical differences were observed. AR may represent a reasonable option in selected scenarios.

Humans↗

The influence of pre-tensioning of meniscal transplants on the tibiofemoral contact area.

The purpose of the present study was to determine the effect of biological in-growth and pre-tensioning on the load transmission function of meniscal transplants. The ability of meniscal transplants to transfer load to the tibial plateau was measured in an animal model. Thirty-six sheep were divided into six groups: group A was the sham group, in group B a medial meniscectomy was performed, and in groups C-F a medial meniscal transplantation with an autograft was carried out. In groups C-F, different levels of pre-tensioning force were applied via bone tunnel sutures (C=0, D=20, E=40, and F=60 N, respectively). The animals were killed after 6 months. The excised knees were mounted in a materials testing machine at 30, 60, and 90 degrees of flexion, and loaded through the femoral axis to 500 N. A thin film pressure measuring transducer (K-scan, Tekscan) was positioned underneath the meniscus in the medial compartment in order to determine contact area and pressure. The mean contact pressure (MCP) of the sham group (A) and the groups with the transplanted meniscus (C-F) was significantly lower in relation to the meniscectomized knees (B). Significant increases in contact area and reductions in peak contact pressure were also observed. Only the meniscal transplantation group with 40 N (E) pre-tension consistently showed a significant or strong trend toward increased contact area, compared to the meniscectomized knees (B) at all flexion angles tested. All meniscal transplanted groups with the exception of the 0 N group (C) showed a significant reduction in peak contact pressure in comparison to the meniscectomized group (B). The results indicate that meniscal transplantation reduces the MCP on the tibial plateau independent of the level of intraoperative pre-tensioning. Furthermore, the menisci pre-tensioned to 40 N showed significantly increased contact area and reduced peak contact pressure in comparison to the meniscectomized knees at all flexion angles tested, and revealed results similar to those reported in the literature for meniscal allografts fixated with bone plugs.

Animals↗

[Treatment concept in complex fractures of the head of the tibia].

Complex tibial condylar fractures are intraarticular fractures with associated lesions of capsule and ligaments, menisci, soft tissue envelope and neurovascular structures. They are in general produced by a high-energy trauma and are usually part of a polytraumatized patient. The frequency for the associated lesions are up 50% for the collateral ligaments, and up to 40% for the cruciate ligaments and the menisci, respectively. The paper presents the crucial steps of clinical and radiological assessment and outlines a concept of treatment, documented by two illustrative cases.

Adult↗

Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images.

The human knee joint represents a complex biomechanical system of which the menisci are an integral component. At present, little data exists describing the meniscal kinematics of the intact knee. Accordingly, a three-dimensional reconstruction magnetic resonance image model was used to explore this issue. Five fresh cadaveric knees were examined by magnetic resonance imaging throughout a full range of motion at 10 degrees intervals. Computer three-dimensional images of the menisci were generated and evaluated for anteroposterior excursion and deformation. During flexion, the posterior excursion of the medial meniscus was 5.1 mm, while that of the lateral meniscus was 11.2 mm. The anterior horn segments were shown to be more mobile than the posterior horn segments bilaterally. Prior limitations of meniscal kinematic assessment may be overcome with advanced imaging techniques such as magnetic resonance imaging and three-dimensional reconstruction. The menisci are highly mobile and easily deformed structures within the intact, cadaveric knee. This imaging technique may prove useful in the elucidation of meniscal dynamics. In the future, similar techniques may be applied clinically to aid in the diagnosis of joint dysfunction.

Biomechanical Phenomena↗

Histologic comparison of tibial articular surfaces against rigid materials and artificial articular cartilage.

After endoprosthetic replacement of the femoral head, marked pathologic changes of the acetabulum, such as penetration and ulceration, often occur. These changes are caused by the rigid material surface properties of the prosthesis and the lack of damping effects. In this study, we compared the time-dependent changes of tibial articular surfaces with three kinds of femoral implant under loading conditions in dogs. Marked pathologic changes of the menisci and tibial articular cartilage were observed from 8 weeks after implantation with hard material implants, whereas the tibial joint surface against an artificial articular cartilage was still intact 24 weeks postoperatively. These results showed clearly that marked pathologic changes of the articular cartilage against rigid materials occurred and were caused by the surface properties of the counterfaces and high friction coefficients of ceramic and metal materials used.

Animals↗