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PubMed2006

The effect of coronoid fractures on elbow kinematics and stability.

BACKGROUND: Coronoid fractures often occur in the setting of more complex elbow trauma. Little is known about the influence of coronoid fracture size on elbow kinematics, particularly in the setting of concomitant ligament injuries. The purpose of this study was to determine the effect of coronoid fractures on elbow kinematics and stability in ligamentously intact and medial collateral ligament deficient elbows and to determine the effect of forearm position on elbow stability in the setting of coronoid fracture. METHODS: Eight cadaveric arms were tested during simulated active dependent elbow motion and gravity-loaded passive elbow motion. Kinematic data were collected from an electromagnetic tracking system. The protocol was performed in ligament origin repaired and medial collateral ligament deficient elbows with radial head arthroplasty. Testing was carried out with the coronoid intact, and with 10% (Type I), 50% (Type II), and 90% (Type III) removed. Varus-valgus angulation of the ulna relative to the humerus and maximum varus-valgus laxity were measured. FINDINGS: With repaired ligament origins and medial collateral ligament deficiency, there was increased varus angulation and increased maximum varus-valgus laxity following simulation of a Type II and Type III coronoid fracture. There was less kinematic change with the forearm in supination than in pronation. INTERPRETATION: Elbow kinematics are altered with increasing coronoid fracture size. Repair of Type II and Type III coronoid fractures as well as lateral ligament repair is recommended where possible. Forearm supination may be considered during rehabilitation following coronoid repair. Valgus elbow positioning should be avoided if the medial collateral ligament is not repaired.

Aged↗
PubMed2001

Ligamentous stabilizers against posterolateral rotatory instability of the elbow.

BACKGROUND: The lateral ulnar collateral ligament, the entire lateral collateral ligament complex, and the overlying extensor muscles have all been suggested as key stabilizers against posterolateral rotatory instability of the elbow. The purpose of this investigation was to determine whether either an intact radial collateral ligament alone or an intact lateral ulnar collateral ligament alone is sufficient to prevent posterolateral rotatory instability when the annular ligament is intact. METHODS: Sequential sectioning of the radial collateral and lateral ulnar collateral ligaments was performed in twelve fresh-frozen cadaveric upper extremities. At each stage of the sectioning protocol, a pivot shift test was performed with the arm in a vertical position. Passive elbow flexion was performed with the forearm maintained in either pronation or supination and the arm in the varus and valgus gravity-loaded orientations. An electromagnetic tracking device was used to quantify the internal-external rotation and varus-valgus angulation of the ulna with respect to the humerus. RESULTS: Compared with the intact elbow, no differences in the magnitude of internal-external rotation or maximum varus-valgus laxity of the ulna were detected with only the radial collateral or lateral ulnar collateral ligament intact (p > 0.05). However, once the entire lateral collateral ligament was transected, significant increases in internal-external rotation (p = 0.0007) and maximum varus-valgus laxity (p < 0.0001) were measured. None of the pivot shift tests had a clinically positive result until the entire lateral collateral ligament was sectioned. CONCLUSIONS: This study suggests that, when the annular ligament is intact, either the radial collateral ligament or the lateral ulnar collateral ligament can be transected without inducing posterolateral rotatory instability of the elbow.

Aged↗
PubMed2001

Anatomical attachments to the proximal phalangeal base--a case for stability.

Transverse midshaft fractures of the proximal phalanx are often unstable and require open reduction and internal fixation. In contrast, fractures of the base of the proximal phalanx are occasionally amenable to conservative treatment in the form of manipulation and a graded mobilisation programme. This stability may be the result of splinting of the fracture by the surrounding anatomical structures, but to our knowledge this has not been previously elucidated anatomically. In this study we define the extent of attachment of the various anatomical structures to the base of the proximal phalanx. The contribution of the joint capsule, collateral ligaments, accessory collateral ligaments, interosseous muscles, and volar (palmar) plate may confer stability to fractures in the proximal 6-9 mm range at the base of the proximal phalanx, once they are reduced and immobilised in the correct positions.

Finger Injuries↗
PubMedDate not supplied

How does magnetic resonance imaging represent histologic findings in the equine digit?

Magnetic resonance (MR) imaging is increasingly used in the diagnosis of equine foot pain, but improved understanding of how MR images represent tissue-level changes in the equine foot is required. We hypothesized that alterations in signal intensity and tissue contour would represent changes in tissue structure detected using histologic evaluation. The study objectives were to determine the significance of MR signal alterations in feet from horses with and without lameness, by comparison with histopathologic changes. Fifty-one cadaver feet from horses with a history of lameness improved by palmar digital analgesia (n = 32) or age-matched control horses with no history of lameness (n = 19) were stored frozen before undergoing MR imaging and subsequent histopathological examination at standard sites (deep digital flexor tendon, navicular bone, distal sesamoidean impar ligament, collateral sesamoidean ligament, and navicular bursa). Using MR images, signal intensity and homogeneity, size, definition of anatomic margins, and relationships with other structures were described. Alterations were graded as mild, moderate, or severe for each structure. For each anatomic site examined histologically the structures were described and scored as no changes, mild, moderate, or severe abnormalities, also taking into account adhesion formation within the navicular bursa detected on macroscopic examination. Alterations in MR signal intensity were related to changes at the tissue level detected by histologic examination. A sensitivity and specificity comparison of MR imaging with histologic examination was used to evaluate the significance of MR signal alterations for detection of moderate-to-severe lesions of the deep digital flexor tendon (DDFT), navicular bone, distal sesamoidean impar ligament (DSIL), collateral sesamoidean ligament (CSL) and navicular bursa. Agreement between the MR and histologic grading was assessed for each structure using a weighted kappa agreement. Direct comparison between histology and MR imaging for individual limbs revealed that signal alterations on MR imaging did represent tissue-level changes. These included structural damage, fibroplasia, fibrocartilaginous metaplasia, and hemosiderosis in ligaments and tendons; trabecular damage, osteonecrosis, fibroplasia, cortical defects, and increased vascularity in bone; and fibrocartilage defects. MR imaging had a high sensitivity and specificity for most structures. MR imaging had high specificity for lesions of the DDFT, CSL and navicular bursa, quite high specificity for lesions of the medulla of the navicular bone and its proximal aspect, with moderate specificity for the DSIL, and distal, dorsal and palmar aspects of the navicular bone, and was sensitive for detection of abnormalities in all structures except the dorsal aspect of the navicular bone. When MR and histologic grades alone were compared, there was good agreement between MR and histologic grades for the navicular bursa, DDFT, navicular bone medulla and CSL; moderate-to-good agreement in grades of the distal and palmar aspects of the navicular bone; fair to moderate in grades of the DSIL, and poor agreement for the dorsal and proximal aspects of the navicular bone. The results of this study support our hypothesis and indicate the potential use and limitations of MR imaging for visualization of structural changes within osseous and soft tissue structures of the equine foot.

Animals↗
PubMed2001

Ambulatory surgery for multi-ligament knee reconstruction with continuous dual catheter peripheral nerve blockade.

PURPOSE: Major reconstructive surgery of the knee traditionally requires an extended hospital stay for pain management. Continuous peripheral nerve blockade is an alternative method of pain control but is seldom used in the ambulatory setting. This case illustrates the use of lumbar plexus and sciatic nerve peripheral catheters for major knee surgery using intermittent bolus dosing for outpatient analgesia. CLINICAL FEATURES: A 20-yr-old male presented for multi-ligamentous knee reconstruction (posterior collateral ligament and revision anterior collateral ligament and lateral collateral ligament). Anesthesia was managed with a lumbar plexus and a sciatic nerve peripheral catheter and a light general anesthetic. Post-operative analgesia was provided with a 12-hr infusion of 0.2% ropivacaine in an over night recovery care centre. Subsequent catheter dosing was performed as an outpatient, twice a day using 0.2% ropivacaine, 10 ml in each catheter (four injections total). This provided 96 hr of analgesia and low supplemental opioid use. CONCLUSION: The use of a lumbar plexus and sciatic nerve peripheral catheter offered an alternative to conventional pain control that worked well in the ambulatory setting. By providing prolonged unilateral lower limb analgesia, extensive knee surgery was performed that would normally require a hospital stay for pain control. Using a bolus dosing method the risk of local anesthetic complications occurring outside of the hospital with a continuous infusion was minimized.

Adult↗
PubMed1999

Mechanoreceptors in collateral knee ligaments: an animal experiment.

The mechanoreceptors in the collateral ligaments of the knee joint in rat hindlimbs were studied. In group II (n=10) the femoral and obturator nerves were sectioned. In both groups III and V (n=20) the sciatic nerve was sectioned. In group V (n=10) the sectioned sciatic nerve was sutured 4 weeks after sectioning. In group IV (n=10) all three nerves were sectioned. Group I (n=10) served as control. After 4 months all animals were killed. The ligaments of the knee joint were preserved and stained with gold chloride, paraffin-embedded and cut in sagittal serial sections. The results showed that 4 months after partial or total denervation of the limb, there was necrosis and a decrease in the number of mechanoreceptors, which was dependent upon the severity and site of the lesion. After suture of the sciatic nerve the increase in mechanoreceptors suggested a regenerative process.

Animals↗
PubMed2003

The anatomy of the posterolateral aspect of the rabbit knee.

The purpose of this study was to determine the anatomy of the posterolateral aspect of the rabbit knee to serve as a basis for future in vitro and in vivo posterolateral knee biomechanical and injury studies. Twelve nonpaired fresh-frozen New Zealand white rabbit knees were dissected to determine the anatomy of the posterolateral corner. The following main structures were consistently identified in the rabbit posterolateral knee: the gastrocnemius muscles, biceps femoris muscle, popliteus muscle and tendon, fibular collateral ligament, posterior capsule, ligament of Wrisberg, and posterior meniscotibial ligament. The fibular collateral ligament was within the joint capsule and attached to the femur at the lateral epicondyle and to the fibula at the midportion of the fibular head. The popliteus muscle attached to the medial edge of the posterior tibia and ascended proximally to give rise to the popliteus tendon, which inserted on the proximal aspect of the popliteal sulcus just anterior to the fibular collateral ligament. The biceps femoris had no attachment to the fibula and attached to the anterior compartment fascia of the leg. This study increased our understanding of these structures and their relationships to comparative anatomy in the human knee. This knowledge of the rabbit's posterolateral knee anatomy is important to understand for biomechanical and surgical studies which utilize the rabbit knee as a model for human posterolateral knee injuries.

Animals↗
PubMedDate not supplied

The fibular collateral ligament-biceps femoris bursa. An anatomic study.

The anatomy of the fibular collateral ligament-biceps femoris bursa is described. The bursa is located lateral to the distal quarter of the fibular collateral ligament and forms an inverted "J" shape around the anterior and anteromedial portions of the ligament. Its most distal margin is just proximal to the fibular head where the fibular collateral ligament inserts, and its more proximal aspect is at the superior edge of the anterior arm of the long head of the biceps femoris muscle. We found this structure in all 50 knees dissected; there was a constant anatomic location of the fibular collateral ligament-biceps femoris bursa in all specimens. Measurement of the anatomic dimensions of the bursa revealed a mean width of 8.4 mm and a mean height of 18 mm. Knowing the prevalence, shape, size, and anatomic location of this bursa may aid the clinician in the differential diagnosis of lateral knee pain.

Aged↗
PubMed1988

Limits of movement in the human knee. Effect of sectioning the posterior cruciate ligament and posterolateral structures.

We applied specific forces and moments to the knees of fifteen whole lower limbs of cadavera and measured, with a six degrees-of-freedom electrogoniometer, the position of the tibia at which the ligaments and the geometry of the joint limited motion. The limits were determined for anterior and posterior tibial translation, internal and external rotation, and varus and valgus angulation from zero to 90 degrees of flexion. The limits were measured in the intact knee and then the changes that occurred with removal of the posterior cruciate ligament, the lateral collateral ligament, the popliteus tendon at its femoral attachment, and the arcuate complex were measured. The cutting order was varied, allowing us to determine the changes in the limits that occurred when each structure was cut alone and the amount of motion of the joint that was required for each structure to become taut and to limit additional motion when the other supporting structures had been removed. Removal of only the posterior cruciate ligament increased the limit for posterior tibial translation, with no change in the limits for tibial rotation or varus and valgus angulation. The additional posterior translation was least at full extension and increased progressively, reaching 11.4 millimeters at 90 degrees of flexion. The progressive increase in posterior translation with flexion was apparently due to slackening of the posterior portion of the capsule, as the translation nearly doubled when the posterolateral structures subsequently were removed. Removal of only the posterolateral extra-articular restraints increased the amount of external rotation and varus angulation. The average increase in external rotation depended on the angle of flexion; it was greatest at 30 degrees of flexion and decreased with additional flexion. At 90 degrees of flexion, the intact posterior cruciate ligament limited the increase in external rotation to only 5.3 degrees, less than one-half of the 13.0-degree increase that occurred at 30 degrees of flexion. Subsequent removal of the posterior cruciate ligament markedly increased external rotation at 90 degrees of flexion, resulting in a total increase of 20.9 degrees. The limit for varus angulation was normal as long as the lateral collateral ligament was intact. When the lateral collateral ligament was cut, the limit increased 4.5 degrees (approximately 4.5 millimeters of additional joint opening) when the knee was partially flexed (to 15 degrees).(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMedDate not supplied

A biomechanical comparison of four reconstruction techniques for the medial collateral ligament-deficient elbow.

The initial strength of the intact medial collateral ligament (MCL) of the elbow and the strength of 4 reconstruction techniques were compared. Twenty cadaveric upper extremities were mounted in a custom jig with the elbow at 90 degrees , and a pneumatic cyclic valgus loading protocol was used. The mean peak load to failure was 142.5+/-39.4 N for the intact ligaments and 53.0+/-9.5 N for the docking reconstructions, 52.5+/-10.4 N for the EndoButton reconstructions, 41.0+/-16.0 N for the interference screw reconstructions, and 33.3+/-7.1 N for the figure-eight reconstructions. The peak load to failure of the MCL reconstructions was inferior compared with the intact ligament (P<.001). No difference in strength was found between the docking and single-strand medial collateral reconstruction with the use of an EndoButton for ulnar fixation (P>.05, beta=.14). Both of these reconstruction methods were stronger than the interference screw or figure-eight technique (P<.004). The optimal fixation method for a single-strand MCL reconstruction may require improved interference screws or a modified EndoButton procedure.

Bone Screws↗
PubMed1996

MR imaging of Baker cysts: association with internal derangement, effusion, and degenerative arthropathy.

PURPOSE: To determine the prevalence of Baker cyst in a general orthopedic population and its association with effusion, internal derangement, and degenerative arthropathy. MATERIALS AND METHODS: Reports of 400 knee magnetic resonance imaging examinations were reviewed. Presence of Baker cyst, effusion, internal derangement (meniscal and/or anterior cruciate ligament tears), medial collateral ligament injury, and degenerative arthropathy was recorded. Uni- and multivariate logistic regressions were used to evaluate associations between Baker cyst and these conditions. Probabilities of having a Baker cyst given these conditions were also calculated. RESULTS: No association was found between Baker cyst and anterior cruciate ligament tear or medial collateral ligament injury. There were significant associations (P < .001) with effusion, meniscal tear, and degenerative arthropathy. There were also significant associations (P < .01) for effusion, meniscal tear, and degenerative arthropathy, independent of one another. Probability of having Baker cyst given the presence of any one variable was .08-.10; any two variables, .19-.21; and all three variables, .38. CONCLUSION: The association between Baker cyst and joint effusion was confirmed. A relationship with meniscal tear and degenerative joint disease independent of effusion was also demonstrated. The probability of having a Baker cyst increases as the number of these associated conditions increases.

Anterior Cruciate Ligament Injuries↗
PubMed2004

Tibial plateau leveling osteotomy in a llama with a ruptured cranial cruciate ligament.

A 3-year-old 155-kg (342-lb) castrated male llama was examined because of left hind limb lameness of acute onset. A diagnosis of cranial cruciate ligament and medial collateral ligament rupture was made, and tibial plateau leveling osteotomy was recommended. The tibial plateau leveling osteotomy procedure was performed as described for dogs, except that 2 orthopedic plates were used to stabilize the osteotomy because of the size of the llama. The medial collateral ligament was sutured and reinforced with 2 strands of size-2 polypropylene placed in a figure-8 fashion between cancellous bone screws in the femur and tibia. Four days after surgery, failure of the medial collateral ligament repair was evident. Approximately 3.5 years after surgery, the llama was reexamined. The owners reported that the llama had full use of its left hind limb, and only mild lameness (grade 1 of 5) was evident. Results suggest that tibial plateau leveling osteotomy may be applicable in camelids with rupture of the cranial cruciate ligament. However, additional study is needed before tibial plateau leveling osteotomy can be routinely recommended. In particular, additional information is needed on the tibial plateau slope in healthy camelids, the role of the fibula in tibial plateau leveling osteotomy procedures, and the prevalence of cranial cruciate ligament rupture in camelids.

Animals↗
PubMed1994

Influence of exogenous growth factors on the expression of plasminogen activators and plasminogen activator inhibitors by cells isolated from normal and healing rabbit ligaments.

In this investigation, we demonstrate that cells from normal and healing rabbit ligaments are selective in their responsiveness to various growth factors. The cells analyzed included fibroblasts isolated from the synovium, the anterior cruciate ligament, and the medial collateral ligament (midsubstance and epiligament). Fibroblasts isolated from scar tissue of medial collateral ligament that had been allowed to heal for 3 weeks also were analyzed. The addition of insulin-like growth factor-2 or transforming growth factor-beta 1 was observed to alter, in a dose-dependent manner, the expression of plasminogen activator and plasminogen activator inhibitor by connective tissue cells. However, the response to these growth factors was cell specific. Fibroblasts isolated from the midsubstance, epiligament, and scar tissue of the medial collateral ligament were responsive to these growth factors; fibroblasts isolated from the anterior cruciate ligament and synovium did not have a detectable response. The cells from the normal and healing medial collateral ligament responded to both growth factors by increasing plasminogen activator inhibitor activity. This was observed at both the protein and RNA level. In contrast, the addition of insulin-like growth factor-1 or acidic or basic fibroblast growth factor to cells derived from normal or healing ligament did not result in any detectable alteration of plasminogen activator or plasminogen activator inhibitor activity. These results are similar to those observed with an explant system and indicate that cells isolated from ligament tissue maintain their responsiveness to these growth factors in the absence of matrix. As the major effect of insulin-like growth factor-2 and transforming growth factor-beta 1 on the cells tested was to increase plasminogen activator inhibitor activity, such an alteration should diminish the activity of plasminogen activator, an enzyme capable of directly and indirectly proteolyzing matrix molecules, and thus contribute to a more anabolic environment.

Animals↗
PubMed1987

[Primary repair of the collateral cubital ligament of the metacarpophalangeal articulation of the thumb using Jenning's barb-wire].

The authors report their technique of primary repair of the ulnar collateral ligament of the metacarpophalangeal joint of the thumb. Under loco-regional anaesthesia with a pneumatic tourniquet, the principal band of the ulnar collateral ligament is reinserted by means of Jenning's barb-wire anchored on the proximal phalanx. After 4 weeks' immobilisation, a regime of splintage is used to regain range of movement.

Bone Wires↗
PubMed1995

Complete dislocation of the knee: spectrum of associated soft-tissue injuries depicted by MR imaging.

OBJECTIVE: Complete knee dislocation is a rare injury. The purpose of this study was to evaluate the spectrum of injuries that are depicted by MR imaging in patients with a dislocation of the knee and to determine if there is any predictive factor that might indicate those patients who may be at risk for popliteal nerve injury. MATERIALS AND METHODS: A retrospective search for patients sustaining traumatic knee dislocations who had radiographs and an MR imaging examination of the knee as part of their initial evaluation was done at three level I trauma centers for the period between 1989 and 1993. Each MR examination was independently reviewed by three osteoradiologists for ligamentous, tendinous, meniscal, and osseous injuries. Equivocal diagnoses were decided by consensus. Only patients who underwent surgery were selected. MR imaging findings were confirmed at the time of surgery. Seventeen patients (15 men, two women; age range, 14-62 years; mean age, 29 years) were studied. Motor vehicle accident, fall from a height, a vehicle striking a pedestrian, and football injury were common mechanisms of injury. Posterior dislocation (seven patients) and anterior dislocation (five patients) were the most common injuries. RESULTS: At the time of surgery, all patients had complete tears of the anterior cruciate ligament, 15 had complete tears of the posterior cruciate ligament, nine had complete tears of the medial collateral ligament, and 12 had tears of the fibular collateral ligament (nine tore both the fibular collateral ligament and the biceps femoris tendon). Popliteal tendon tears occurred in eight patients (six complete, two partial). Of the six patients with complete tears of the popliteal tendon, five occurred at the musculotendinous junction; all were the result of either posterior or posterolateral dislocations. Four patients had injuries to the peroneal nerve; three of the four also had tears of the popliteal tendon. On MR imaging, the integrity of the anterior cruciate and lateral collateral ligaments was correctly depicted in all 17 patients; evaluation of the posterior cruciate ligament resulted in one false-positive and one false-negative diagnosis of a tear; evaluation of the medial collateral ligament resulted in one false-positive diagnosis of a tear; and one false-positive diagnosis of a tear occurred with evaluation of the popliteal tendon. CONCLUSION: Knee dislocations cause extensive disruption of the ligaments that stabilize the knee and the surrounding soft-tissue structures, including the popliteal artery. Nearly all will result in disruption of the cruciate ligments and, often, injury of the collateral ligaments. An injury to the popliteal tendon denotes a more severe injury. The mechanism of injury that results in a popliteal tendon tear may also increase the possibility of a peroneal nerve injury. Recognition of this pattern of injuries on MR imaging enables precautionary observation for ischemic changes of the foot to be instituted in patients that otherwise may not be considered at risk for acute vascular compromise.

Adolescent↗
PubMed2006

Pellegrini-Stieda disease: a heterogeneous disorder not synonymous with ossification/calcification of the tibial collateral ligament-anatomic and imaging investigation.

OBJECTIVE: Ossification/calcification around the medial femoral condyle has been known as Pellegrini-Stieda (PS) disease for almost 100 years. Little attention has been given to magnetic resonance (MR) imaging characteristics. Our purpose is to demonstrate the anatomy in the medial femoral compartment and imaging findings of PS disease, determining the sites and patterns of ossification. DESIGN AND PATIENTS: In a cadaveric study seven specimens were dissected to show the anatomic relations of the tibial collateral ligament (TCL) and the tendon of the ischiocondylar part of the adductor magnus muscle, in the medial femoral epicondyle. In order to determine the nature of ossification/calcification in PS disease, MR imaging and radiographic findings in nine patients were analyzed by two observers with attention to the specific site, shape, and orientation of the ossification and its relationship to the tibial collateral ligament (TCL) and adductor magnus tendon. Available clinical history was recorded. A classification system addressing different sites and patterns of ossification was developed. RESULTS: The anatomic study showed that the TCL and the adductor magnus tendon insert at different sites in the medial femoral condyle and there is no continuation; however, some fibers of the posterior bundle of the TCL overlap the anterior aspect of the adductor magnus tendon. The imaging study showed that shape, orientation, and location of the abnormal calcification and ossification were similar on radiographic and MR imaging analysis. Ossification had an inferior orientation in six cases, a superior orientation in two cases, and both in one case. Four patterns of ossification were noted: (I) a beak-like appearance with an inferior orientation and femoral attachment was present in five cases; (II) a drop-like appearance with an inferior orientation, parallel to the femur, was evident in one case; (III) an elongated appearance with a superior orientation, parallel to the femur, was seen in two cases; and (IV) a beak-like appearance with an inferior and superior orientation, attached to the femur, was seen in one case. The ossification was present in the TCL in six cases, in the adductor magnus tendon in two cases, and in both in one case. The coronal plane was best in detecting and categorizing the ossification. CONCLUSION: Our data indicate that ossification in PS disease is not confined to the TCL but may also involve the adductor magnus tendon. In some cases, it can be related to the anatomic proximity (overlap) of the fibers of these two structures. PS disease should not be regarded as synonymous with ossification of the TCL. The ossification may be classified into four types. No clinical differences among these types appear to exist.

Aged↗
PubMed2000

Adaptation of post-traumatic angiogenesis in the rabbit knee by apposition of torn ligament ends.

Apposition of torn ligament ends has been shown to have a beneficial effect on healing of the medial collateral ligament; however, the mechanism underlying this improved recovery is unclear. Excessive post-traumatic angiogenesis, an inherent component of soft-tissue regeneration, may be functionally detrimental in relatively hypovascular tissues such as ligaments. The present study therefore examined the relationship between contact of transected ligament ends and vascular remodeling. Female New Zealand White rabbits were subjected to a gap injury, Z-plasty apposition, or sham operation to the midsubstance of the medial collateral ligament. Six weeks after treatment, the volume of vessels supplying the healing zone of the medial collateral ligament, as well as the ipsilateral lateral collateral ligament, posterior cruciate ligament. menisci, and medial capsule, was quantified by carmine red vascular casting. The volume of vessels supplying the neoligamentous scar formed by gap injury to the medial collateral ligament was found to be twice that of ligaments that had undergone the sham operation, and lateral collateral ligament and meniscal vascularity was also augmented in the injured joint. The medial collateral ligaments that underwent Z-plasty apposition exhibited a level of vascularity comparable with that of the control ligaments that had undergone the sham procedure, whereas meniscal and lateral collateral ligament vascularities remained elevated in this group. Capsular and posterior cruciate ligament vascularities were unaffected by gap injury or Z-plasty to the ipsilateral medial collateral ligament. These findings indicate that injury to the medial collateral ligament not only stimulates angiogenesis in the healing ligament, but other ipsilateral soft tissues also undergo vascular remodeling. Furthermore, apposition of an injured medial collateral ligament modifies these pro-angiogenic events, and this may partly explain why contact of torn ligament ends is beneficial for post-traumatic recovery of an injured joint.

Adaptation, Physiological↗
PubMed1996

The morphology of ligament insertions after failure at low strain velocity: an evaluation of ligament entheses in the rabbit knee.

The morphology of failed rabbit knee entheses is described after in vitro load to failure testing at low strain velocity. Avulsion fracture was the dominant failure mode both for the cruciate ligaments and the medial collateral ligament. The patellar ligament became avulsed in most cases from the patellar insertion. The ligamentous anterior attachment of the medial meniscus failed by a midsubstance rupture and the posterior fibrocartilaginous attachment by a rupture near to the meniscal horn. On histological inspection the failure characteristics usually appeared more elaborate, involving to different degrees all portions of the bone-ligament-bone complexes. Avulsion fracture through subchondral bone was often combined with a partial ligament midsubstance rupture. In few cases avulsion from the cement line was combined with a rupture between the uncalcified fibrocartilage and the ligament. The medial collateral ligament failed in one case entirely at the cement line of its femoral insertion. Horizontal rupture through the calcified fibrocartilage and a vertical cleavage crossing the tidemark were also observed. The superficial portion of the patellar ligament failed with a midsubstance rupture, and the deeper part with an avulsion through the calcified fibrocartilage or an avulsion fracture. The complex failure characteristics may be attributed to uneven loading, nonuniformity of the structure, and specific anatomical location. Subchondral bone beneath femoral and tibial insertions seems to be weaker than the transitional zone between soft tissue and hard bone at the enthesis. The overall inferior structural quality of a ruptured ligament has to be taken into account when parts of the original structure are used for suturing or reconstruction.

Animals↗