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PubMed1993

Anatomy of the oblique retinacular ligament of the index finger.

The available literature includes conflicting descriptions of the anatomy and function of the oblique retinacular ligament. We have studied this ligament in the index finger to better define its presence, configuration, points of attachment, length, and relationship to the proximal interphalangeal joint axis. Twenty fresh frozen index fingers were dissected. Five additional specimens were decalcified, mounted, sectioned transversely at 1 mm intervals and studied under the microscope. An oblique retinacular ligament was identified on the radial side of the index finger in 95% and on the ulnar side in 90% of the specimens. The radial oblique retinacular ligament was usually longer and more developed than the ulnar oblique retinacular ligament. Proximally, the ligament arose from the middle third of the proximal phalanx and the A-2 pulley whereas, distally, it inserted into the lateral extensor band with a fan-shaped expansion centered 4 to 6 mm distal to the proximal interphalangeal joint line. In 70% of the specimens, the oblique retinacular ligament was supplemented by a contribution from the proximal cruciform pulley (C-1). Histologic cross sections also confirmed the presence of the oblique retinacular ligament but not the supplemental contribution arising from the C-1 pulley. The relationship of the oblique retinacular ligament to the proximal interphalangeal joint axis is dependent on the proximal interphalangeal joint position; the ligament lies palmar to the proximal interphalangeal joint axis only when the proximal interphalangeal joint is flexed.

Cadaver↗
PubMed2006

In vitro investigation of the effect of medial patellofemoral ligament reconstruction and medial tibial tuberosity transfer on lateral patellar stability.

PURPOSE: Two different operative techniques for stabilizing the patella against lateral displacement movement were investigated. TYPE OF STUDY: In vitro experimental study. METHODS: Five human cadaver knee specimens with a normal Q-angle were mounted in a kinematic knee simulator and investigated under simulated isokinetic extension motions. Patellar movement was measured while a 100-N laterally directed subluxation load was applied to the patella. Ligament loading of the medial patellofemoral ligament was measured using a strain gauge based buckle transducer inserted in the fibers of the ligament. The knee was evaluated in an intact physiologic state, as well as after medial transfer of the tibial tuberosity, and after the medial patellofemoral ligament was transected and reconstructed using a hamstring autograft. RESULTS: A significant reduction in lateral displacement and ligament load was observed with the use of the hamstring autograft reconstruction compared with the medial transfer of the tibial tuberosity. CONCLUSIONS: Medial transfer of the tibial tuberosity showed no significant relief of ligament loading and stabilizing effect on patellar movement, whereas reconstruction of the medial patellofemoral ligament showed a significant stabilizing effect on patellar movement. CLINICAL RELEVANCE: In cadaver specimens, we evaluated the effect of tibial tubercle transfer and the patellofemoral ligament and found that reconstruction of the patellofemoral ligament alone was sufficient to restore stability in a cadaveric model. Additionally, we found that the flexion angle had little effect on the loading of the medial patellofemoral ligament autograft, which would support early mobilization of patients after surgery. We found that the graft was not unduly loaded.

Aged↗
PubMed2004

Comparative effects of monopolar radiofrequency energy and conservative management of mechanical properties of elongated lateral collateral ligament in rabbits: an experimental study.

OBJECTIVE: We examined the biomechanical effects of shrinkage in elongated rabbit lateral collateral ligament. DESIGN: This study was designed in an attempt to evaluate the energy effects of monopolar radiofrequency on strained but not ruptured ligaments. BACKGROUND: In treatment of ligament injuries difficulty in reducing increased laxity after trauma and recurrence of instability are important factors for failure. METHODS: Ligament elongation and laxity were achieved in operating room by applying varus stress for multiple times. In Group C ( n = 8 ), elongated lateral collateral ligaments were treated only with above-knee cast, while in Group S ( n = 8 ), they were treated with shrinkage and above-knee casts. The un-operated sides were labeled as control groups. At the 12th week after surgery the animals were sacrificed and hind limbs were disarticulated. Removing the other soft tissues around knee, only lateral collateral ligaments were left intact. Biomechanical analyses of the effects of two different treatment methods were compared by performing a pulling-out test. RESULTS: Considering maximum load and stiffness, conservatively treated ligaments were stronger and stiffer than shrunken ligaments ( P < 0.05 ). CONCLUSION: Biomechanical values were altered by both treatment methods. Reflecting an alteration in intra-molecular structure, the main alteration was the decrease of strength in shrunken ligaments. In ligament injuries, we concluded shrinkage not to be superior to conservative treatment.

Animals↗
PubMed2005

Effects of separate application of three growth factors (TGF-beta1, EGF, and PDGF-BB) on mechanical properties of the in situ frozen-thawed anterior cruciate ligament.

OBJECTIVE: To clarify effects of a separate application of TGF-beta1, EGF, and PDGF-BB on the material properties of the in situ frozen-thawed anterior cruciate ligament. DESIGN: Twenty-eight rabbits were divided into four groups after undergoing the in situ freeze-thaw treatment in the right anterior cruciate ligament. In 3 of the 4 groups, 4 ng TGF-beta1, 20 ng EGF, and 4 microg PDGF-BB was applied to the frozen anterior cruciate ligament, respectively. In the remaining sham treatment group, only fibrin sealant as a vehicle was applied. Each animal was sacrificed at 12 weeks after surgery. BACKGROUND: If the role of growth factors in ligament healing and remodeling is understood, better therapies can be designed for ligament trauma. METHODS: The freeze-thaw treatment was performed three times using the originally developed cryo-probe. The cross-sectional area of the anterior cruciate ligament was measured by the optical non-contact method. After preconditioning, each specimen was stretched to failure. The ligament strain was determined with a video dimension analyzer. RESULTS: The tensile strength and the tangent modulus of the anterior cruciate ligament in the TGF-beta1 group was significantly higher than in the sham group, but significantly lower than in the normal control group. There were no significant differences in the strength and the modulus between the EGF group, the PDGF-BB group, and the sham group. CONCLUSIONS: In this model, an application of 4 ng TGF-beta1 significantly inhibited some of the material deterioration that occurs in the in situ frozen-thawed anterior cruciate ligament, while an application of 20 ng EGF or 4 microg PDGF-BB did not significantly affect the deterioration. RELEVANCE: This information will be useful in the future to develop a new biological therapy for ligament reconstruction to prevent the graft deterioration after transplantation.

Animals↗
PubMed2005

Detailed investigation of the relationship between the inferior laryngeal nerve including laryngeal branches and ligament of Berry.

BACKGROUND: Studies about the anatomic relationship between the inferior laryngeal nerve (ILN) and the ligament of Berry are insufficient, despite controversy in the literature. In addition, the relationship between the laryngeal branches of the ILN and the ligament of Berry has not been investigated. STUDY DESIGN: Sixty specimens (120 sides) were examined for this study, including 41 male and 19 female cadavers between the ages of 40 and 89 years at death. RESULTS: The nerve trunk or its anterior and posterior laryngeal branches run posterolateral to the ligament in 51 and 39 sides, respectively. The nerve trunk or both its laryngeal branches passed posteromedial to the ligament in 12 and 7 sides, respectively. In seven sides, the anterior branch of the ILN was located posterolateral and the posterior branch was posteromedial to the ligament. In three sides, the anterior (motor) branch of the ILN penetrated the ligament of Berry. In one right side, a nonrecurrent laryngeal nerve arose from the vagal nerve at the level of ligament of Berry. The nerve divided into the anterior and posterior laryngeal branches just above posterior surface of the ligament; both branches extended parallel to it. CONCLUSIONS: We have shown that the nerve was located not only posterolateral to the ligament but also posteromedial to it. Additionally, unlike other authors, we have shown that the anterior (motor) branch of the recurrent laryngeal nerve penetrated the ligament of Berry in 2.5% of 60 specimens.

Adult↗
PubMed2006

Cervical facet capsular ligament yield defines the threshold for injury and persistent joint-mediated neck pain.

The cervical facet joint has been identified as a source of neck pain, and its capsular ligament is a likely candidate for injury during whiplash. Many studies have shown that the mechanical properties of ligaments can be altered by subfailure injury. However, the subfailure mechanical response of the facet capsular ligament has not been well defined, particularly in the context of physiology and pain. Therefore, the goal of this study was to quantify the structural mechanics of the cervical facet capsule and define the threshold for altered structural responses in this ligament during distraction. Tensile failure tests were preformed using isolated C6/C7 rat facet capsular ligaments (n=8); gross ligament failure, the occurrence of minor ruptures and ligament yield were measured. Gross failure occurred at 2.45+/-0.60 N and 0.92+/-0.17 mm. However, the yield point occurred at 1.68+/-0.56 N and 0.57+/-0.08 mm, which was significantly less than gross failure (p<0.001 for both measurements). Maximum principal strain in the capsule at yield was 80+/-24%. Energy to yield was 14.3+/-3.4% of the total energy for a complete tear of the ligament. Ligament yield point occurred at a distraction magnitude in which pain symptoms begin to appear in vivo in the rat. These mechanical findings provide insight into the relationship between gross structural failure and painful loading for the facet capsular ligament, which has not been previously defined for such neck injuries. Findings also present a framework for more in-depth methods to define the threshold for persistent pain and could enable extrapolation to the human response.

Animals↗
PubMed2005

Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: Part II.

PURPOSE: This study is a continuation of our previous investigation of the ligaments stabilizing the scaphoid and lunate. We evaluated the effects of sectioning the scapholunate interosseous ligament, radioscaphocapitate ligament, and scaphotrapezial ligament in 3 sequences. METHODS: Three sets of 8 cadaver forearms were placed in a wrist simulator and moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the 3 ligaments were sectioned in various sequences and after the wrist was moved through 1,000 cycles of motion. RESULTS: Sectioning only the scaphotrapezium ligament (ST) or the radioscaphocapitate ligament (RSC) resulted in minimal angular changes to the motion of the scaphoid and lunate. Sectioning of the scapholunate interosseous ligament (SLIL) or 1,000 cycles of repetitive wrist motion after ligament sectioning altered scaphoid and lunate kinematics. CONCLUSIONS: Based on these findings it was concluded that the SLIL is the primary stabilizer and the RSC and ST are secondary stabilizers of the scapholunate articulation. Repetitive motion after ligament injury probably results in further carpal instability.

Adult↗
PubMedDate not supplied

Coracoclavicular ligament reconstruction using the lateral half of the conjoined tendon.

To preserve the coracoacromial (CA) ligament, we have used the lateral half of the conjoined tendon as an autograft source to replace the coracoclavicular (CC) ligament. The purpose of this study is to compare the ultimate tensile strength of the lateral 12 mm of the conjoined tendon with that of the CA ligament and the CC ligament. Eight paired cadaveric male shoulders were tested to tensile failure with a custom pneumatic testing apparatus. Although the lateral 12 mm of the conjoined tendon was stronger than the CA ligament, this difference was not statistically significant (P =.37). However, the intact CC ligament (621 +/- 209 N) was approximately 250% stronger than either the lateral 12 mm of the conjoined tendon (265 +/- 79 N, P <.001) or the CA ligament (246 +/- 69 N, P <.001). We believe that the lateral half of the conjoined tendon is a viable alternative autograft source for reconstruction of the CC ligament in cases of symptomatic acromioclavicular joint dislocation. Though not as strong as the native CC ligaments, the conjoined tendon is slightly stronger than the commonly used CA ligament.

Acromioclavicular Joint↗
PubMed2004

[Intracarpal ligament injuries associated with wrist fractures: a prospective radioclinical study of 40 patients].

PURPOSE OF THE STUDY: We performed a prospective study to search for arthrographic signs in favor of intracarpal ligament lesions occurring concomitantly with wrist fractures. We looked for a relationship between type of fracture and displacement and examined their impact on early functional outcome. MATERIAL AND METHODS: The series included 40 patients treated over a 1-year period. All 40 patients had a displaced wrist fracture requiring surgical treatment. A three-phase arthrography was performed during the initial operation in order to search for injuries involving the scapho-lunate, luno-pyramidal or triangular complex ligaments. A second arthrography was performed at the time the osteosynthesis material was removed. All patients were followed one year postperatively. Functional outcome was recorded at one year. RESULTS: Abnormal images were found in 57% of the patients at the first arthrography. Injury to the triangular complex predominated, followed by combined injuries. There was no statistical correlation between type of fracture, degree of displacement, and presence of ligament lesions (p > 0.05). Lesions of the triangular fibrocartilaginous complex (TFCC) were significantly increased (p = 0.04) in the event of intra-articular fracture. Age and gender did not influence ligament injury. At one year, the functional outcome was statistically comparable between patients with and without ligament injury. At the second arthrography, we observed only five cases where cure of the luno-pyramidal ligament had been achieved. DISCUSSION: Intracarpal ligament injuries associated with wrist fractures are frequent. Age had no effect on occurrence of ligament injury in our series, similar to findings reported by others. Likewise, the type of fracture had no effect. Data in the literature show that intra-articular fractures and highly-displaced fractures aggravate ligament injury. Our functional results at one year did not demonstrate any significant difference in patients with and without ligament injury. A 3 or 5-year follow-up might provide further insight. Nevertheless, neglected scapho-lunate lesions still have a bad reputation in the literature, leading us to search for such lesions and to provide adapted treatment in all patients aged less than 50 years presenting a displaced fracture of the wrist.

Aged↗
PubMed1995

The intrinsic and extrinsic ligaments of the wrist. A correlation of collagen typing and histologic appearance.

20 fresh frozen human wrist specimens were dissected. Gross and histological examination and biochemical evaluation were performed on the intrinsic ligaments (scapho-lunate and luno-triquetral) and extrinsic ligaments (radio-scapho-capitate and radio-lunate). All ligaments were observed to have longitudinal collagen bundles. The intrinsic ligaments had large amounts of fibrocartilage near insertions and no elastin, while the extrinsic ligaments had little fibrocartilage and sparse amounts of elastin. The intrinsic ligaments were noted to have significantly more collagen Type 3 (41%) than the extrinsic ligaments (19%). These findings suggest that structural differences between the intrinsic and extrinsic ligaments of the wrist may in part account for the biomechanical observations that the intrinsic ligaments are stronger and elongate further prior to failure than the extrinsic ligaments.

Cadaver↗
PubMed2001

Anterior lateral ankle ligament damage and anterior talocrural-joint laxity: an overview of the in vitro reports in literature.

OBJECTIVE: To provide a clear overview of the literature on the relationship between increased lateral ankle ligament damage and anterior talocrural-joint laxity. DESIGN: A systematic review of the literature. BACKGROUND: Diagnostic methods for inversion injuries of the ankle have remained controversial throughout the years. An instrumented test for anterior talocrural-joint laxity could be a diagnostic tool for evaluation of anterior lateral ankle ligament function. METHODS: An advanced electronic database search using MEDLINE and EMBASE was performed to find studies describing the correlation between lateral ankle ligament damage and talocrural-joint laxity. Two reviewers assessed the methodological quality for each study and agreement was noted. Two reviewers extracted all relevant data with respect to methodology, motion constraints and laxity measurement. RESULTS: The quality assessment resulted in 5 studies being scored as high quality and 5 as low quality. Different test devices were used to apply the load and measure the displacement. All in vitro tests applied a load to the calcaneus and subsequently measured the translation of the talus and/or calcaneus relative to the tibial dome. Rotation in the transversal and frontal plane was restricted in 8 tests. After analysis of the results presented by nine different studies, the mean value of anterior talocrural-joint laxity with intact ligaments is 4.2 mm. After sectioning of the anterior talofibular ligament, the mean anterior laxity value is 6.5 mm. The mean anterior laxity value after sectioning of the calcaneofibular ligament increases to 8.4 mm. The mean anterior laxity value with the foot in dorsal flexion (3.1 mm) is less than the mean value with the foot in neutral position (4.5 mm) or in plantar flexion (4.7 mm). The applied load and the anterior laxity values between the different studies vary greatly. CONCLUSIONS: Each ligament section results in significantly increased talocrural-joint laxity. Talocrural-joint laxity can be used as a measure for damage to the anterior talofibular ligament and/or the calcaneofibular ligament. From this review, it is neither possible to give universal recommendations about the optimal flexion angle for testing talocrural-joint laxity as a measure for lateral ankle ligament function, nor to recommend the ideal load for performing the test. RELEVANCE: The development of an instrumented test as a diagnostic tool for anterior talocrural-joint laxity in the clinical setting is near at hand and practicable.

Ankle Injuries↗
PubMed2001

Regional material properties of the human hip joint capsule ligaments.

The hip joint capsule functions to constrain translation between the femur and acetabulum while allowing rotational and planar movements. Despite the crucial role it plays in the pathogenesis of hip instability, little is known about its biomechanical properties. The goal of this study was to determine the regional material properties of the iliofemoral and ischiofemoral ligaments of the capsule. Ten human cadaveric specimens of each ligament were tested to failure in tension. The stress at failure, strain at failure, strain energy density at failure, toe- and linear-region elastic moduli, and the Poisson's ratio were measured for each ligament. The strain to failure was greatest in the ischiofemoral ligament, while no significant difference was noted in failure stress by region or ligament. The Young's moduli of elasticity ranged from 76.1 to 285.8 MPa among the different ligaments, and were generally consistent with properties previously reported for the shoulder capsule. The elastic moduli and strain energy density at failure differed by region. No significant differences in Poisson's ratio were found by region or ligament. The average Poisson's ratio was approximately 1.4, consistent with anisotropic behavior of ligamentous tissues. Understanding the material properties of the hip capsule may help the orthopaedic surgeon better understand normal ligament function, and thereby choose a surgical approach or strategy of repair. Furthermore, knowledge of the normal mechanical function of the hip capsule ligaments could assist in the evaluation of the success of a repair.

Aged↗
PubMed2002

Alpha-smooth muscle actin is expressed by fibroblastic cells of the ovine anterior cruciate ligament and its free tendon graft during remodeling.

Contractile fibroblastic cells expressing the alpha-smooth muscle actin isoform, so-called myofibroblasts, have been identified to play a possible role during the healing of the medial collateral ligament by means of restoring the tissues in situ strain via extracellular matrix contraction. Recently, these cells have also been identified to be a normal part of the human anterior cruciate ligament. It has been hypothesized that myofibroblasts play a role in the wrinkling of the extracellular matrix. The goal of the present study was to identify myofibroblasts in the intact ovine anterior cruciate ligament and a free autologous tendon graft during remodeling after anterior cruciate ligament reconstruction. In 36 mature merino sheep the anterior cruciate ligament was replaced with an ipsilateral Achilles tendon split graft. Midsubstance tissue samples were immunostained for alpha-smooth muscle actin at 6, 9, 12, 24, 52, and 104 weeks. Myofibroblasts were identified in the intact ovine anterior cruciate ligament as well as in the Achilles tendon graft prior to implantation. During remodeling the first myofibroblasts were found at six weeks within newly formed fiber bundles. At 24, 52, and 104 weeks myofibroblast distribution and cell density were similar to those of the intact ovine anterior cruciate ligament. These findings indicate that alpha-smooth muscle actin containing fibroblastic cells are a regular part of the intact as well as the remodeled anterior cruciate ligament. There is evidence that myofibroblasts may be involved in maintaining tissue homeostasis in the mature ligament e.g., by means of crimp formation. The presence of these cells during the early remodeling may further indicate that alpha-smooth muscle actin containing fibroblastic cells are involved in the earliest stages of fiber bundle formation. The role and function of this special cell type for the anterior cruciate ligament needs to be further clarified.

Achilles Tendon↗
PubMed2001

The sacroiliac part of the iliolumbar ligament.

The iliolumbar ligament has been described as the most important ligament for restraining movement at the lumbosacral junction. In addition, it may play an important role in restraining movement in the sacroiliac joints. To help understand its presumed restraining effect, the anatomy of the ligament and its orientation with respect to the sacroiliac joints were studied in 17 cadavers. Specific dissection showed the existence of several distinct parts of the iliolumbar ligament, among which is a sacroiliac part. This sacroiliac part originates on the sacrum and blends with the interosseous sacroiliac ligaments. Together with the ventral part of the iliolumbar ligament it inserts on the medial part of the iliac crest, separate from the interosseous sacroiliac ligaments. Its existence is verified by magnetic resonance imaging and by cryosectioning of the pelvis in the coronal and transverse plane. Fibre direction, length, width, thickness and orientation of the sacroiliac part of the iliolumbar ligament are described. It is mainly oriented in the coronal plane, perpendicular to the sacroiliac joint. The existence of this sacroiliac part of the iliolumbar ligament supports the assumption that the iliolumbar ligament has a direct restraining effect on movement in the sacroiliac joints.

Aged↗
PubMed1999

An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint.

We provide a detailed and comprehensive anatomic description of the ligaments stabilizing the trapezium and trapeziometacarpal joint. Sixteen ligaments were identified. Fourteen ligaments inserted onto the trapezium and 2 others attached independently to the thumb metacarpal. The ligaments inserting onto the trapezium were the superficial anterior oblique, deep anterior oblique (beak ligament), dorsoradial, posterior oblique, ulnar collateral, dorsal trapezio-trapezoid, volar trapezio-trapezoid, dorsal trapezio-second metacarpal, volar trapezio-second metacarpal, trapezio-third metacarpal, volar scaphotrapezial, radial scaphotrapezial, transverse carpal, and trapezio-capitate ligaments. The remaining 2 ligaments attach onto the thumb metacarpal and are the proper intermetacarpal and the dorsal intermetacarpal. The dorsoradial and deep anterior oblique ligaments play a substantial role in stabilizing the trapeziometacarpal joint, and the deep anterior oblique ligament may function as a pivot for the first metacarpal during palmar abduction to allow rotation (pronation). The dorsal trapezio-second metacarpal, volar trapezio-second metacarpal, and trapezio-third metacarpal ligaments function as tension bands and are required to prevent instability from cantilever bending forces on the trapezium.

Aged↗
PubMedDate not supplied

Effects of repetitive subfailure strains on the mechanical behavior of the inferior glenohumeral ligament.

The mechanical response of the inferior glenohumeral ligament to varying subfailure cyclic strains was studied in 33 fresh frozen human cadaver shoulders. The specimens were tested as bone-ligament-bone preparations representing the 3 regions of the inferior glenohumeral ligament (superior band and anterior and posterior axillary pouches) through use of uniaxial tensile cycles. After mechanical preconditioning, each specimen was subjected to 7 test segments, consisting of a baseline strain level L1 (400 cycles) alternating with either 1 (group A, 10 shoulders), 10 (group B, 13 shoulders), or 100 (group C, 10 shoulders) cycles at increasing levels (L2, L3, L4) of subfailure strain. Cycling to higher levels of subfailure strain (L2, L3, L4) produced dramatic declines in the peak load response of the inferior glenohumeral ligament for all specimens. The group of ligaments subjected to 100 cycles of higher subfailure strains demonstrated a significantly greater decrease in load response than the other 2 groups. Ligament elongation occurred with cyclic testing at subfailure strains for all 3 groups, averaging 4.6% +/- 2.0% for group A, 6.5% +/- 2.6% for group B, and 7.1% +/- 3.2% for group C. Recovery of length after an additional time of nearly 1 hour was minimal. The results from this study demonstrate that repetitive loading of the inferior glenohumeral ligament induces laxity in the ligament, as manifested in the peak load response and measured elongations. The mechanical response of the ligament is affected by both the magnitude of the cyclic strain and the frequency of loading at the higher strain levels. The residual length increase was observed in all of the specimens and appeared to be largely unrecoverable. This length increase may result from accumulated microdamage within the ligament substance, caused by the repetitively applied subfailure strains. The clinical relevance of the study is that this mechanism may contribute to the development of acquired glenohumeral instability, which is commonly seen in the shoulders of young athletes who participate in repetitive overhead sports activities.

Adult↗
PubMed2001

Stability after medial collateral ligament release in total knee arthroplasty.

Six knees from cadavers were tested for change in stability after release of the medial collateral ligament with posterior cruciate-retaining and substituting total knee replacements. Load deformation curves of the joint were recorded in full extension and 30 degrees, 60 degrees, and 90 degrees flexion under a 10 N-m varus and valgus torque, 1.5 N-m internal and external rotational torque, and a 35 N anterior and posterior force to test stability in each knee. The intact specimen and posterior cruciate ligament-retaining total joint replacement were tested for baseline comparisons. The superficial medial collateral ligament was released, followed by release of the posterior cruciate ligament. The knee then was converted to a posterior-stabilized implant. After medial collateral ligament release, valgus laxity was statistically significantly greater at 30 degrees, 60 degrees, and 90 degrees flexion after posterior cruciate ligament sacrifice than it was when the posterior cruciate ligament was retained. The posterior-stabilizing post added little to varus and valgus stability. Small, but significant, differences were seen in internal and external rotation before and after posterior cruciate ligament sacrifice. The posterior-stabilized total knee arthroplasty was even more rotationally constrained in full extension than the knee with intact medial collateral ligament and posterior cruciate ligament.

Arthroplasty, Replacement, Knee↗
PubMed2002

A study of ulnar collateral ligament of the thumb metacarpophalangeal joint.

The current study examined the biomechanical properties of intact and repaired ulnar collateral ligaments of the metacarpophalangeal joint of the thumb to determine a safe rehabilitation protocol after repair. In the first part of the study mechanical properties of the ligament were examined and the induced stress and strain were determined during simulated pinch and grip. In the second part of the study the strength and limitations of ulnar collateral ligament repair using a mini-Mitek bone suture anchor was determined. The biomechanical study was done on 16 fresh-frozen thumbs from male cadavers. Failure load, maximum stress, and Young's modulus of intact ulnar collateral ligament were 294.3 +/- 28.2 N, 11.4 +/- 1.2 MPa, and 37.3 +/- 5.1 MPa, respectively. There was no significant correlation between the low grip force and the ligament strain. There was, however, a significant correlation between the pinch force and the ligament strain. The failure load and joint rigidity of intact ulnar collateral ligaments were significantly higher (3.1 and 2.3 times, respectively) than the mini-Mitek repaired ligaments. The current study suggests that pinch activity during the rehabilitative process after repair or reattachment of the ulnar collateral ligament should be eliminated. Repaired ligaments with mini-Mitek bone suture anchors may be able to do a moderate range of motion during postoperative rehabilitation; however, additional in vivo studies are necessary before any clinical recommendation is made.

Aged↗