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PubMed2002

Fate of donor bone marrow cells in medial collateral ligament after simulated autologous transplantation.

A potential strategy to enhance ligament healing by transplantation of mesenchymal stem cells (MSCs), which are demonstrated to differentiate into fibroblast-like cells in vitro, is presented. The objective of this study was to follow transplanted nucleated cells from bone marrow, which contain MSCs, in the healing medial collateral ligament (MCL) over time, and to examine their phenotype and survivability. It was hypothesized that MSCs in nucleated cells from bone marrow would differentiate into fibroblast-like cells in the healing ligament following adaptation to the environment. The transplantation model employed in this study eliminates the immune response to a donor by the recipient using a transgenic rat (donor), which does not produce foreign protein from transgenes, and its wild-type rat (recipient) in order to simulate autologous transplantation. The MCL of the wild-type rat was ruptured, where 1 x 10(6) nucleated cells of bone marrow from the transgenic rat were injected. The transgenes in transplanted nucleated cells were detected throughout the healing MCL for 28 days by in situ hybridization. At 3 days, many donor cells were evident in the injury site and fascial pocket, and some were found in the midsubstance. Morphologically, transplanted cells with elongated nuclei were found at the ruptured edge of the midsubstance and surface of the unruptured site after 3 days. At 28 days, these cells continued to survive in the healing MCL. Their shapes were similar to those of surrounding recipient MCL fibroblasts. Thus, transplanted cells might differentiate into fibroblasts. Therefore, it was demonstrated that there is a potential for nucleated cells from bone marrow to serve as a vehicle for therapeutic molecules as well as to be a source in enhancing healing of ligaments.

Animals↗
PubMed1992

Water content alters viscoelastic behaviour of the normal adolescent rabbit medial collateral ligament.

Testing environment is an important factor in the outcome of mechanical tests on connective tissue. The purpose of this investigation was to determine the effect of ligament water content on ligament mechanical behaviour by altering the test environment. Water content of medial collateral ligament (MCLs) from 19 three-month-old New Zealand White rabbits was varied in subsets of ligaments pairs by means of immersion in 2, 10 or 25% sucrose or 0.9% phosphate-buffered saline (PBS) solutions for 1 h. One knee joint was cycled 50 times in the designated solution (experimental), while the contralateral knee (uncycled control) was simultaneously soaked in the same tank. Following cycling, the water contents of both test and control ligaments were determined. Water contents of 22 normal MCLs were determined immediately post-sacrifice and served as 'normal water content' controls. Normalized peak cyclic load changes were used as a measure of the viscoelastic behaviour of each MCL. Results demonstrated that only ligaments soaked (but not cycled) in a 10% sucrose solution had water contents (60.5 +/- 2.5%) which were statistically similar to the 22 fresh normal MCLs (63.9 +/- 6.0%). Ligaments soaked in PBS (74.0 +/- 1.3%) or 2% sucrose (69.2 +/- 2.3%) had significantly higher water contents compared to fresh normal MCLs. Ligaments with higher water contents (e.g. soaked in PBS or 2% sucrose) demonstrated greater cyclic load relaxation compared to ligaments with lower contents (e.g. soaked in 25 or 10% sucrose). Different fluid test environments can significantly alter ligament water content and, in turn, significantly affect ligament viscoelastic behaviour.

Animals↗
PubMed1980

[Biomechanical and histologic evaluation of refixation of ruptured collateral ligaments (author's transl)].

This paper describes the use of a new one-hole plate for the refixation of ligaments. The anchorage of ligaments was of sufficient strength as judged by biomechanical experiments on medial collateral ligaments of sheep in vivo and knees of human cadavers. Microangiographic and histologic investigations showed good vascularization and normal structure of the ligament under the one-hole plate.

Animals↗
PubMed2005

Fixation of tendon grafts for collateral ligament reconstructions: a cadaveric biomechanical study.

PURPOSE: To compare the biomechanical properties of 4 methods of fixation of tendon grafts to bone as used for ligament reconstructions. METHODS: Thirty-two metacarpals were harvested from fresh-frozen cadavers and stripped of soft tissue. Flexor tendons were harvested from the same cadavers and cut into 2-mm-wide strips. Each tendon was fixed to a metacarpal head at the site of origin of a collateral ligament. Four different methods of fixation were tested. In group 1 the tendon was fixed to the bone with a 4.0-mm Arthrex bio-tenodesis interference screw (Arthrex, Inc., Naples, FL). In group 2 the tendon was passed through a bone tunnel and fixed with a 3.2-mm mini-Acutrak screw (Acumed, LLC, Hillsboro, OR) that was inserted in interference mode. In group 3 the tendon was passed through a bone tunnel and fixed with sutures tied over a polyethylene button. In group 4 the tendon was fixed with a mini-Mitek bone suture anchor (Mitek Worldwide, Norwood, MA). All specimens were clamped into a linear loading machine and loaded until failure. Statistical analysis was performed by 1-way analysis of variance testing. RESULTS: The differences in maximal tensile strength and stiffness were statistically significant when comparing any 2 groups. The Arthrex biotenodesis interference screw was the strongest and stiffest fixation method, followed by the Acutrak screw inserted in interference mode. Next was the suture tied over a button method. The mini-Mitek bone suture anchor was the weakest. CONCLUSIONS: Interference screw fixation of tendons to bone has statistically significant higher pullout strength and stiffness than 2 other commonly used fixation methods. The use of interference screws for fixation of tendon grafts to bone for hand ligament reconstructions is a promising new surgical technique.

Biomechanical Phenomena↗
PubMed1998

Sprains of the radial collateral ligament of the metacarpophalangeal joint of the thumb. A series of 14 cases.

Fourteen surgically treated radial sprains of the M.P. joint of the thumb, are reported. 8 were recent cases, 6 were longstanding. At the time of surgery, the extensor head was severed in 4 cases, the APB tendon in 6 cases, the dorsal articular capsule in 9. The radial collateral ligament was elongated 6 times, ruptured 4 times, and presented bony avulsion in 4 cases. The mean postoperative immobilization was 37 days. 13 patients were reviewed with a mean follow-up of 22 months. Only eight were satisfied. The mean loss of motion was 27 degrees. The mean laxity, assessed on specific dynamic X-rays, was 6 degrees. 3 patients presented with radiographic arthritis, all of them with chondral lesions at the time of surgery. Despite the absence of Stener's lesion, the authors recommend surgery when volar subluxation or radial laxity is observed > 10 degrees.

Adult↗
PubMed2005

Biomechanical study using fuzzy systems to quantify collagen fiber recruitment and predict creep of the rabbit medial collateral ligament.

In normal daily activities, ligaments are subjected to repeated loads, and respond to this environment with creep and fatigue. While progressive recruitment of the collagen fibers is responsible for the toe region of the ligament stress-strain curve, recruitment also represents an elegant feature to help ligaments resist creep. The use of artificial intelligence techniques in computational modeling allows a large number of parameters and their interactions to be incorporated beyond the capacity of classical mathematical models. The objective of the work described here is to demonstrate a tool for modeling creep of the rabbit medial collateral ligament that can incorporate the different parameters while quantifying the effect of collagen fiber recruitment during creep. An intelligent algorithm was developed to predict ligament creep. The modeling is performed in two steps: first, the ill-defined fiber recruitment is quantified using the fuzzy logic. Second, this fiber recruitment is incorporated along with creep stress and creep time to model creep using an adaptive neurofuzzy inference system. The model was trained and tested using an experimental database including creep tests and crimp image analysis. The model confirms that quantification of fiber recruitment is important for accurate prediction of ligament creep behavior at physiological loads.

Algorithms↗
PubMed1991

Dacron collateral ligament reconstruction with proximal interphalangeal joint arthroplasty.

A porous Dacron (Phoenix Bioengineering, Bridgeport, PA) tendon is described for collateral ligament reconstruction and augumentation with proximal interphalangeal joint implant arthroplasty. Eight cases with a minimum follow-up of 15 months are reviewed. Diagnoses include posttraumatic arthritis and osteoarthritis, as well as rheumatoid arthritis. The porous Dacron tendon is constructed as a collagen-like weave. It has been useful in patients who have insufficient local tissue to achieve lateral proximal interphalangeal joint stability. In selected cases, it can obviate the need for a tendon graft and provide an alternative to arthrodesis.

Adult↗
PubMed2005

Viscoelastic properties of the human medial collateral ligament under longitudinal, transverse and shear loading.

Ligament viscoelasticity controls viscous dissipation of energy and thus the potential for injury or catastrophic failure. Viscoelasticity under different loading conditions is likely related to the organization and anisotropy of the tissue. The objective of this study was to quantify the strain- and frequency-dependent viscoelastic behavior of the human medial collateral ligament (MCL) in tension along its longitudinal and transverse directions, and under shear along the fiber direction. The overall hypothesis was that human MCL would exhibit direction-dependent viscoelastic behavior, reflecting the composite structural organization of the tissue. Incremental stress relaxation testing was performed, followed by the application of small sinusoidal strain oscillations at three different equilibrium strain levels. The peak and equilibrium stress-strain curves for the longitudinal, transverse and shear tests demonstrate that the instantaneous and long-time stress-strain response of the tissue differs significantly between loading conditions of along-fiber stretch, cross-fiber stretch and along-fiber shear. The reduced relaxation curves demonstrated at least two relaxation times for all three test modes. Relaxation resulted in stresses that were 60-80% of the initial stress after 1000 s. Incremental stress relaxation proceeded faster at the lowest strain level for all three test configurations. Dynamic stiffness varied greatly with test mode and equilibrium strain level, and showed a modest but significant increase with frequency of applied strain oscillations for longitudinal and shear tests. Phase angle was unaffected by strain level (with exception of lowest strain level for longitudinal samples) but showed a significant increase with increasing strain oscillation frequency. There was no effect of test type on the phase angle. The increase in phase and thus energy dissipation at higher frequencies may protect the tissue from injury at faster loading rates. Results suggest that the long-time relaxation behavior and the short-time dynamic energy dissipation of ligament may be governed by different viscoelastic mechanisms, yet these mechanisms may affect tissue viscoelasticity similarly under different loading configurations.

Adult↗
PubMed1998

Pregnancy-induced changes in rabbit medial collateral ligament vasoregulation.

The ligaments of weight-bearing joints are known to become mechanically inferior during pregnancy, and it has been postulated that this may be due to changes in tissue perfusion. Calcitonin gene-related peptide (CGRP) and epinephrine exert a tonic influence on the vasculature of the medial collateral ligament (MCL), and the present study examined whether these vasoactive influences were altered by pregnancy. Ligament perfusion experiments were performed on primigravid New Zealand White rabbits with the use of laser Doppler perfusion imaging. In pregnant animals (day 29), MCL basal perfusion fell significantly compared with control; however, values returned to normal 5 days postpartum. In normal joints, topical application of CGRP resulted in a dose-dependent increase in MCL perfusion, whereas epinephrine administration caused a dose-dependent fall in blood flow. During pregnancy, the vasodilator effect of CGRP was completely abolished, whereas adrenergic vasoconstriction was greater than normal. Both responses returned postpartum. Pregnancy in the rabbit produces hypoemia in the MCL, and this phenomenon may be effected by a tempering of CGRP dilator responses and an augmentation of alpha-adrenoceptor-mediated vasoconstriction.

Animals↗
PubMed2005

Gap junctions of the medial collateral ligament: structure, distribution, associations and function.

Ligaments are composed of two major components: cells and extracellular matrix. The cells express gap junction proteins and are arranged into a series of rows that traverse the tissue, suggesting that all the cells of the tissue are functionally interconnected. The results of our study demonstrate that medial collateral ligament (MCL) cells do not have a uniform fusiform morphology or placement along a row of cells as previously suggested, but rather display a complex placement and form that weaves within the collagen matrix in a manner that is far more extensive and complex than previously appreciated. Within this morphological context, we find that MCL cells in vivo contain functional gap junctions (verified using fluorescence recovery after photobleaching) that are localized to sites of close cell-cell contact, and this pattern imparts or reflects a bipolarity inherent to each cell. When we studied ligament cells in conventional tissue culture we found that this bipolarity is lost, and the placement of gap junctions and their related proteins, as well as general cell morphology, is also altered. Finally, our study demonstrates, for the first time, that in addition to gap junctions, adherens junctions and desmosomes are also expressed by MCL cells both in vivo and in vitro and map to sites of cell-cell contact.

Adherens Junctions↗
PubMed1990

The effects of temperature on the viscoelastic properties of the rabbit medial collateral ligament.

There are disparate views on the effects of temperature on the mechanical properties of ligaments and tendons. We attempted to resolve the inconsistencies by testing the medial collateral ligaments of twelve, three-month old New Zealand white rabbits in both elastic-dominated and viscous-dominated tests between 25 degrees C and 55 degrees C. We found that in elastic-dominated monotonic loading, the loading portions of the load-extension curves were mathematically similar. Differences could be accounted for through a base-line shift of the origin caused by additional relaxation and thermal contraction/expansion of the apparatus and specimen. In tests where the viscous component of behavior was manifest, we found results similar to those of other investigators. Thus we conclude that in assessing the effects of temperature on the mechanical properties of tissues it is important to account for both temperature and initial positions of the apparatus and specimen, and to consider the effects of both relaxation and thermal contraction/expansion.

Animals↗
PubMedDate not supplied

Ulnar collateral ligament rupture of the first metacarpophalangeal joint: a frequently missed injury in the emergency department.

Between July 1991 and December 1995, 28 patients elected to consult one of the senior authors for a second opinion or were referred to him by their family physician after being reassured and discharged from our emergency department with the simple diagnosis of "soft tissue contusion" to the thumb. Physical examination and stress radiographs of these patients revealed a missed injury to the ulnar collateral ligament (UCL) of the first metacarpophalangeal joint in 18 patients (64.3%), 12 of whom required surgical repair. Apparently, UCL injuries are frequently underestimated in our emergency department, although the real number is unknown because some patients may have decided to seek further treatment elsewhere. In addition to the numerous trivial injuries that are frequently seen in any emergency department, emergency physicians have the added responsibility of detecting those injuries that require referral to a specialist.

Collateral Ligaments↗
PubMed1985

Bovine xenograft collateral ligament replacement in the dog.

A study of the use of glutaraldehyde-stabilized bovine xenograft material as a collateral ligament replacement in 16 dogs has been done. Six xenograft implant complexes harvested 4 months postoperatively failed in tension at 772.2 +/- 463.5 versus 799.7 +/- 162.7 N (+/- 1 SD) for controls (p greater than 0.05, paired t test). Histologic evaluation in 10 dogs after implants of up to 1 year duration demonstrated a progressive invasion of the xenograft by host tissues. Xenograft remnants were easily identifiable at 1 year. The host tissues invaded in parallel to the passive collagen scaffolding of the xenograft and consisted of vessels and fibroblastic elements that produced collagen of host origin.

Animals↗
PubMed2003

Reconstructive procedure to repair chronic injuries to the collateral ligament of metacarpophalangeal joints of the hand.

We have devised a reconstructive procedure to repair chronic injuries to the collateral ligament of metacarpophalangeal (MCP) joints. It comprises palmaris longus tendon grafting into a bone tunnel and suturing onto the base of the residual ligament without involving fixation of the tendon graft stump. Thirteen patients were treated for injured MCP joints: thumb/ulnar, ten cases; thumb/radial, two; and middle finger/radial, one. All patients had pain and instability of average 41 degrees in the affected MCP joints. The patients were followed at an average period of five years and nine months. Pain and joint instability disappeared in all patients. The mean MCP joint range of motion (ROM) was 1 degrees on extension and 58 degrees on flexion. The tip pinch strength averaged 4.8 kg. The gratifying results obtained using this method are attributed to the fact that optimal tension of the ligament and satisfactory ROM can be achieved during the course of rehabilitation.

Activities of Daily Living↗
PubMed1987

New experimental procedures to evaluate the biomechanical properties of healing canine medial collateral ligaments.

Both clinical and animal studies have indicated that early mobilization and exercise may improve the healing of injured medial collateral ligaments (MCLs). To investigate these effects, transected canine MCLs were subjected to three different treatment regimens: (a) no surgical repair with 6 weeks mobilization; (b) surgical repair with 3 weeks immobilization followed by 3 weeks remobilization; and (c) surgical repair with 6 weeks immobilization. After sacrifice, knee laxity was measured in a newly designed varus-valgus (V-V) laxity device. Each knee was tested subsequently in tension to determine the structural properties of the femur-MCL-tibia complex (FMTC) and the mechanical properties of the healing MCL substance. It was found that the V-V laxity increased for all experimental knees, but that early mobilization enhanced joint stability. The structural properties of the FMTC and the mechanical properties of the MCL substance were also lower than the contralateral controls. Again, the early mobilization groups had better results.

Animals↗
PubMed1987

Hand function after injuries to the collateral ligaments of the metacarpophalangeal joint of the thumb.

An assessment was made of 34 patients who had sustained injuries to collateral ligaments of the metacarpophalangeal joint of the thumb. 23 patients had symptoms in the thumb, when seen at a mean of 38.7 months later, but these were minor in all but one patient. Assessment of pinch strength revealed that 43% of patients had less than 80% of the strength of the opposite side. This was not related to the presence of symptoms or to demonstrable instability of the joint, but the incidence of such weakness was greater when the operation had been delayed by more than three weeks. Pinch strength should be measured in two positions (key pinch and lateral pinch) as there is occasionally a large discrepancy between the two.

Finger Injuries↗