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At least 415 records · Page 23Linked to original sources
PubMed2000

Biomechanical analysis of knee hyperextension and of the impingement of the anterior cruciate ligament: a cinematographic MRI study with impact on tibial tunnel positioning in anterior cruciate ligament reconstruction.

This study analyzed the interaction between the anterior cruciate ligament (ACL) and the intercondylar notch roof (INR) in hyperextension of the knee using magnetic resonance cinematography. Cinematographic image series of 15 knees were investigated. Two independent observers identified the image that displayed the beginning of contact between the ACL and the INR. They determined knee extension on this image and on the image that displayed maximum hyperextension of the knee. Correlations between a variable representing impingement and the inclination angle of the INR, the anterior laxity of the knee, and full hyperextension were examined. Theoretical, impingement-free tibial tunnel positions for the knees were calculated as a percentage of the anteroposterior tibial width. All ACLs of the knees in this study made contact with the INR. The average extension angle at the beginning of impingement was -6.3 +/- 3.8 degrees. There were significant correlations between impingement and maximum manual displacement as measured with the arthrometer (r = 0.77; P < 0.001), maximum hyperextension (r = 0. 67; P = 0.007), and notch roof angle (r = -0.73; P = 0.002). There were biomechanically acceptable tunnel positions for all knees but one. Hyperextension is physiologically associated with impingement of the ACL. In uninjured knees there was a correlation between ACL impingement and hyperextension, inclination of the INR, and maximum manual displacement of the tibia. Impingement free tibial tunnel positioning is possible in most knees without notchplasty.

Adolescent↗
PubMed2005

Characteristics of periodontal ligament subpopulations obtained by sequential enzymatic digestion of rat molar periodontal ligament.

Periodontal ligament (PDL) consists of different cell populations in various differentiation stages. In the present study, we isolated cell populations from rat molar PDL by sequential enzymatic digestion and characterized growth potential and mineralization activity of the PDL subpopulations (PDL-SP) to throw light on the mechanism of PDL remodeling and, in its turn, periodontal tissue regeneration. PDL attached to extracted rat molars was digested 2 mg/ml collagenase and 0.25% trypsin at 37 degrees C for 30 min. Then four consecutive digestions were performed for 20 min each in a fresh digestive solution. The solutions were centrifuged to collect released cells and 5 PDL subpopulations (30M-, 50M-, 70M-, 90M-and 110M-PDL-SP) were obtained. Light microscopic observation showed that about a half of PDL in width attached on the root surface of extracted teeth and 30M-PDL-SP was considered to contain cells mainly from middle portion of PDL. Scanning electron microscopic examination indicated that 110M-PDL-SP was enriched by root lining cementoblastic cells. 30M-PDL-SP showed a high level of proliferative activity. Although the growth potential of a subpopulation decreased in PDL-SP toward the root surface, 110M-PDL-SP had a high proliferative activity equivalent to that of 30M-PDL-SP. Analyses of alkaline phosphatase (ALP) and mineralization activities showed that higher activities in PDL-SP toward the surface of roots and that 110M-PDL-SP had the highest activity of ALP and the largest number of mineralization nodules. The present study shows as supposed by previous studies on cell kinetics in PDL that subpopulations with larger growth potential were generally located in the middle portion of PDL and those with higher mineralization activities toward the surface of the roots. It is suggested, however, that a possible pathway of PDL cell turnover may exist within the PDL-SP on the root surface in addition to the generally recognized pathway from the middle area of PDL to root surface.

Alkaline Phosphatase↗
PubMed2004

Sacro-spinous ligament fixation peri-operative complications in 195 cases: visual approach versus digital approach of the sacro-spinous ligament.

OBJECTIVE: To evaluate sacro-spinous ligament fixation (SLF) peri-operative complications. STUDY DESIGN: Monocentric, retrospective study. Department of Gynecology, SIHCUS-CMCO, University Hospital, Strasbourg, France. Between January 1990 and December 2000, 195 women, mean age 63.2 years old (40-90), underwent a vaginal SLF. Ninety point eight percent of women were post-menopaused and 27.9% of these had a hormonal substitution. About 24% of patients had prior hysterectomy, 20% vaginal prolapse repair and 22% urinary stress incontinence repair. SLF was performed in 1.5% of cases without any other procedures and it was combined with the following: rectocele and elytrocele repair in 89.2%, hysterectomy in 72.3%, cystocele repair in 52.8% and stress incontinence repair in 15.3% of cases. In 107 cases, the SLF attachment was placed under digital control and in 88 cases under visual control. RESULTS: The mean hospitalisation stay was of 8.5 +/- 2.6 days (4-26). About 41% of women presented a complication. Major complications were represented by 3.6% of bladder injury, 0.5% of uretero-vaginal fistula, 0.5% of vascular injuries, 0.5% of thromboembolic events. In 38% of cases patients had minor complications: urinary tract infections (29%), temporary urinary retention (5.6%), local complications (4.5%), and other complications (3%). The only specific SLF complication in this data was a vascular injury and in this case the SLF was performed under digital control. CONCLUSIONS: The global peri-operative complication frequency of SLF is high. It is mainly represented by non-specific complications, secondary to the combined procedures and not to the SLF itself. The specific complications due to SLF, all of which are major ones, can be avoided or diagnosed earlier, by using the visual approach technique.

Adult↗
PubMed2005

Ultrastructural differences in cranial cruciate ligaments from dogs of two breeds with a differing predisposition to ligament degeneration and rupture.

Cranial (anterior) cruciate ligament (CCL) samples were obtained from dogs of the Labrador retriever (LR) and greyhound (GH) breeds, of which the former but not the latter is predisposed to CCL rupture. Electron microscopy revealed that the collagen fibril diameters of GHs were larger than those of LRs (P=0.03). Histological examination revealed a "fibrocartilaginous" appearance of CCLs in seven of eight GHs, and, to a lesser extent, in three of eight LRs. The formation of fibrocartilage is clearly not a disadvantage to the healthy racing GH, and cannot be regarded as a pathological degeneration in this breed. It is suggested that fibrocartilage is formed as a beneficial physiological adaptation to the compression of CCLs caused by tensile stress as a result of the tightening of two twisted bands. Fibrocartilage would appear to protect CCLs in the GH, but it may be indicative of a mild degenerative change, which may eventually lead to rupture in the LR.

Animals↗
PubMed2000

Proximity of the posterior cruciate ligament insertion to the popliteal artery as a function of the knee flexion angle: implications for posterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to determine if an optimal knee flexion angle existed that would minimize the risk of neurovascular injury from the passage of transtibial hardware during posterior cruciate ligament (PCL) reconstruction. TYPE OF STUDY: Cadaveric. MATERIALS AND METHODS: Fourteen fresh-frozen cadaveric knees were mounted in a Plexiglas apparatus that could be set at 5 different knee flexion angles (0 degrees, 45 degrees, 60 degrees, 90 degrees, and 100 degrees ) while joint distention was maintained. Each knee underwent magnetic resonance imaging in the axial and sagittal planes at each of the 5 flexion angles to determine the distance between the PCL tibial insertion and popliteal artery. RESULTS: The mean distance, over all 5 flexion angles, between the PCL insertion and the popliteal artery in the axial plane was 7.6 mm, whereas the mean distance in the sagittal plane was 7.2 mm. There was a significant increase in distance with progressive flexion in both planes. Maximum mean distances were noted at 100 degrees of flexion in both the axial (9.9 mm) and sagittal (9.3 mm) planes. An artificial line mimicking the path of a transtibial drill passed through the popliteal artery in 10 of 10 cases at the 0 degrees, 45 degrees, 60 degrees, and 90 degrees angles, and in 6 of 10 cases at the 100 degrees angle. CONCLUSIONS: The results of this study suggest that increasing knee flexion reduces, but does not completely eliminate, the risk of arterial injury during arthroscopic PCL reconstruction.

Aged↗
PubMed1988

[Conventional x-ray diagnosis of the knee joint following surgical repair of ligament injuries and after ligament replacement plasty].

Characteristic radiological findings following operative repair of the ligaments of the knee joint are described and related to the type of operative procedure. The operations depend on a number of basic principles which are discussed in detail. The majority of these surgical procedures are not apparent radiographically. It is only by having a knowledge of the individual procedures and of the resulting functional changes in the knee joint, that the informed radiologist can make a correct assessment of the post-operative radiographs. Defects resulting from bone drilling can be recognised tomographically in the early postoperative phase, or if they persist for any reason. This could be confirmed by experiments on pigs' knees.

Adolescent↗
PubMedDate not supplied

Single-strand ligament reconstruction of the medial collateral ligament restores valgus elbow stability.

The purpose of this study was to determine the contribution of the central portion of the anterior bundle of the medial collateral ligament (MCL) to elbow stability and to evaluate the effectiveness of a single-strand MCL reconstruction in restoring elbow stability. Testing of 11 fresh-frozen upper extremities was first performed on the intact elbow and then with the capsule, flexor-pronator muscle group, posterior bundle, anterior or posterior band, and central band cut sequentially. Next, a single-strand reconstruction of the MCL was performed. The elbow was moved passively through a full arc of flexion in both varus and valgus gravity-loaded positions. Ulnar movement with respect to the humerus was analyzed by means of an electromagnetic tracking system. Maximum varus-valgus laxity throughout the arc of supinated flexion and pronated flexion was 6.6 degree plus minus 2.4 degree and 7.4 degree plus minus 2.0 degree, respectively, for the intact specimen, 34.2 degree plus minus 5.6 degree and 37.7 degree plus minus 11.8 degree for the specimen with all of the medial valgus elbow stabilizers cut, and 9.0 degree plus minus 2.5 degree and 10.5 degree plus minus 2.7 degree for the reconstructed specimen. Maximum varus-valgus laxity was not significantly different among any of the sectioning sequences until the central band was cut (P <.0001). There was no significant difference in maximum varus-valgus laxity between the intact and reconstructed elbows (P <.05). Our results demonstrate that the central band is an important valgus stabilizer of the elbow and that a simplified single-strand reconstruction is able to restore stability to the MCL-deficient elbow.

Aged↗
PubMedDate not supplied

A functional comparison of animal anterior cruciate ligament models to the human anterior cruciate ligament.

Many investigators have used animal models to clarify the role of the human anterior cruciate ligament (ACL). Because none of these models are anatomically and biomechanically identical to the human ACL, there exists a need for an objective comparison of these models. To do this, we used a universal force-moment sensor to measure and compare the in situ forces, including magnitude and direction, of the ACL and the anteromedial (AM) and posterolateral (PL) bundles of human, pig, goat, and sheep knees. An Instron was used to apply 50 and 100 N anterior tibial loads at 90 degrees of knee flexion, while a universal force-moment sensor was used to measure the forces applied by the ACL to the tibia, the in situ force of the ACL. We found significant differences between the magnitude of force experienced by the goat and sheep ACL and AM and PL bundles when compared with the human ACL and AM and PL bundles. Also, the direction of the in situ force in the ACL and AM bundles of the goat and sheep were different from the human. The pig knee differed from the human only in the magnitude and direction of the in situ force in the PL bundle in response under anterior tibial loading. A tally of the significant differences between the animal models and the human knees indicates that goat and sheep knees may have limitations in modeling the human ACL, while the pig knee may be the preferred model for experimental studies.

Aged↗
PubMed1991

Anterior cruciate ligament reconstruction using the Gore-tex ligament.

Twenty two Army patients with synthetic (Gore-tex) anterior cruciate ligament (ACL) reconstructions were reviewed (mean follow up 18 months). Reconstruction appeared to abolish the pivot shift sign in all cases, but some subjective instability persisted in all but 6 patients. Outcome was also assessed by medical (PULHHEEMS) grading: 6 patients were fully fit (graded L2), 7 returned to moderate activity but not full fitness (L3), and 9 remained severely incapacitated (L7 or L8) with 4 of this group being medically discharged. Specific operative complications included: prosthesis breakage (3 partial, 1 complete), infected prosthesis(1), and problems with the tibial screw(3). The range and frequency of complications was similar in other series. Physical fitness is an integral part of a soldier's job, placing particular demands on the knee and on surgical repair of knee injuries. Reports on the Gore-tex ACL prosthesis in other groups have been more encouraging, but there are difficulties in comparing this study with others. ACL insufficiency remains a serious problem, with implications for a soldier's fitness and career. The Gore-tex prosthesis improves stability but does not always allow a soldier to return to full fitness.

Adult↗
PubMedDate not supplied

Treatment of the medial collateral ligament injury. I: The importance of anterior cruciate ligament on the varus-valgus knee laxity.

The purpose of this study was to explain the functional roles of the medial collateral ligament (MCL) and the ACL and how they affect the kinematics of the knee joint after isolated MCL injury. Varus-valgus joint laxity was quantitatively measured using a device which allowed various degrees of freedom (DOF) of joint motion during application of a varus-valgus bending moment to the canine knee joint. When the knee motion was limited to 3 DOF (varus-valgus rotation, proximal-distal, and medial-lateral translation), valgus laxity increased significantly (171%) after sectioning the MCL. Thus, the MCL was the primary restraint to the valgus bending moment in the 3 DOF mode. However, the effect of sectioning the MCL on valgus laxity became minimal (21% increase) when the DOF of knee motion was increased to 5 (by adding axial tibial rotation and anterior-posterior translation). In this situation, external and internal tibial axial rotation were coupled with the varus and valgus rotation of the knee joint, respectively, and the ACL also functioned to restrain the varus-valgus rotation. The results of this study suggest that under normal knee joint motion, the functional deficit of the MCL in valgus rotation was compensated for by the remaining structures, especially by the ACL.

Animals↗
PubMedDate not supplied

Assessment of quadriceps/hamstring strength, knee ligament stability, functional and sports activity levels five years after anterior cruciate ligament reconstruction.

The purpose of this study was to examine individuals 5 years after ACL reconstruction and analyze changes involving strength, stability, function, and sports activities. Nineteen males and six females, mean age = 31.4 +/- 7.31 years, participated in this study. Fifteen subjects had received extraarticular and ten subjects had received intraarticular ACL reconstructions. Subjects completed a 100 point subjective functional activity questionnaire and a sports participation survey. Knee ligament stability was assessed during an objective knee examination. Isokinetic quadriceps and hamstring muscle strength were tested at 240 and 120 deg/sec using the Cybex II dynamometer. Anterolateral rotatory instability and positive Lachman were elicited on the operated leg for 80% of the subjects. No significant relationship was found between objective instability and the functional activity score. For the intraarticular group, a significant correlation (P less than 0.05) was found between increased quadriceps and hamstring strength on the operated leg and return to functional activities. Subjects' functional activity score was positively correlated (P less than 0.001) with their ability to participate in sports. Subjects participating in sports involving cutting and twisting motions were less successful in returning to their preinjury participation levels and reported more subjective complaints of pain, swelling, and/or instability. These results indicate that long-term progressive rehabilitation emphasizing increased quadriceps and hamstring strength to approximate the nonoperated leg may enhance successful return to functional and sports activities after ACL reconstruction.

Adult↗
PubMedDate not supplied

An in vitro study of the Müller anterolateral femorotibial ligament tenodesis in the anterior cruciate ligament deficient knee.

The biomechanical effectiveness of the Müller anterolateral femorotibial ligament (ALFTL) iliotibial band tenodesis on anterior stability and internal rotational stability of the ACL deficient knee was investigated in six cadaver knees. Anterior drawer and internal rotation of the tibia were measured at 15 degrees increments from 0 degrees to 90 degrees in response to 50 N of anteriorly applied tibial force and 3 Nm of internally applied internal torque, respectively, in the intact knee, the ACL excised knee, and following the ALFTL reconstruction. A strain gage was used to measure the resting graft tension and to measure strain in the graft during the load-displacement tests. The Müller ALFTL tenodesis failed to return normal anterior stability to the ACL deficient knee (P less than 0.05). The tenodesis did, however, reduce the anterior laxity of the ACL deficient knee from 30 degrees to 90 degrees of knee flexion (P less than 0.05). The tenodesis overconstrained internal tibial rotation of the ACL excised knee from 30 degrees to 90 degrees (P less than 0.05). Measurements of strain in the tenodesis supported the load-displacement findings that the tenodesis was most effective in constraining anterior drawer and internal tibial rotation from 30 degrees to 90 degrees of knee flexion.

Adult↗
PubMedDate not supplied

A multicenter study on the results of anterior cruciate ligament reconstruction using a Dacron ligament prosthesis in "salvage" cases.

A multicenter study is presented on 80 patients who underwent ACL reconstruction using a Dacron (E.I. Du Pont de Nemours and Co., Wilmington, DE) ligament prosthesis. Patient selection was based on a history of a failed autologous reconstruction and/or primary repair of the ACL. These selection criteria are unique and have not been previously reported in the literature. The frequency of prior intraarticular ACL surgery was 1.24 procedures per patient and 1.68 when combined with prior extraarticular reconstructions. Forty-one patients had a mean followup of 28 months (24 to 42 months). The mean followup for all of the patients was 21 months. The graft was augmented with autologous tissue in 59 cases and used as a pure prosthesis in the rest. Functionally, the mean Lysholm score improved from 40 to 81 points. The percentage of a combined excellent/good Lysholm rating increased from 6% to 60%. The Tegner activity rating level improved from 2 to 4. The percentage of a negative Lachman sign, anterior drawer, and pivot shift was approximately 75% at followup. There was no significant difference between the results of augmentation and nonaugmentation cases, indicating that the graft acts as a permanent prosthesis rather than as a scaffold or stint. The patients showed a significant improvement considering their preoperative global instability.

Adult↗
PubMedDate not supplied

Load sharing and graft forces in anterior cruciate ligament reconstructions with the Ligament Augmentation Device.

Buckle transducers were used to directly measure load sharing and overall force in three segment (semitendinosus, gracilis, Ligament Augmentation Device) and two segment (patellar tendon, LAD) composite ACL grafts during the application of anteriorly directed loads to a series of five fresh knee specimens with a pneumatic load apparatus. The total graft forces generated in the two segment and three segment composite reconstructions during this immediate postoperative state were highly variable when compared to the normal ACL in each specimen, and were irreproducible among the five specimens. Load sharing among the graft components occurred and was also variable in both reconstructions, with this variation being greater in the three segment graft. The LAD carried an average of 45% of the total graft force in the three segment graft and 28% in the two segment graft. Further work is required to clarify the source of the variability in the total graft force and load sharing observed in this study.

Biomechanical Phenomena↗
PubMed1978

The repair of cruciate ligaments with flexible carbon fibre. A longer term study of the induction of new ligaments and of the fate of the implanted carbon.

Carbon fibre appears to induce the formation of tendon in both animals and humans. Experiments have been conducted in sheep in which new anterior cruciate ligaments have been induced in response to the implantation of filamentous carbon fibre. Long-term studies indicate that the carbon fibre slowly breaks up at the site of implantation and later begins to appear in the regional lymph nodes.

Achilles Tendon↗
PubMed1986

Reconstruction of the anterior cruciate ligament by allogeneic tendon graft. An operation for chronic ligamentous insufficiency.

We describe the use of allogeneic human tendon as an intra-articular replacement for the anterior cruciate ligament. Depending on the type and degree of functional instability we recommend the addition, in some cases, of supplementary extra-articular procedures. We have reviewed 31 patients at least two years after operation and have found that 30 of them had been able to return to full sporting activities. The indications for operation and the techniques are discussed and the use of allogeneic tendon is recommended.

Adolescent↗