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Plantar flexion injuries of the ankle. An experimental study.

A biomechanical study was designed to test the hypothesis that isolated plantar flexion of the ankle can produce avulsion fractures of the medial and lateral malleoli without fracture of the posterior articular surface of the tibia. Cadaver specimens were subjected to a standard plantar flexion force in the Burstein torsion testing machine. They showed the following typical patterns of injury in 26 of 32 ankles: (1) avulsion of the anterior ankle capsule; (2) a short oblique distal fibular fracture or fibular avulsion of the anterior talofibular ligament; and (3) an oblique medial malleolar fracture or a tear of the deep fibers of the deltoid ligament. Of particular interest was the direction and location of the medial malleolar fracture. This pattern, previously identified with supination-external rotation injuries, was also produced by isolated plantar flexion, which may be attributed to the anatomical attachments of the deltoid ligament on the medial malleolus, as well as the position of the foot and direction of the injuring force.

Adult↗

5. Recent advances in sports medicine.

New research has changed our perception and management of common injuries. Magnetic resonance imaging and arthroscopy of the hip have shown that labral injuries, chondral injuries, rim lesions, synovitis and tears of the ligament teres are common causes of hip, groin and low-back pain. Hip arthroscopy is used both as a diagnostic and therapeutic tool; it has been shown to be of benefit in recent traumatic labral injury, but disappointing in the management of chronic hip pain (which may be associated with degenerative change, and chondral lesions of the acetabulum). The McConnell multimodal physiotherapy regimen is effective in treating patellofemoral pain. Anterior cruciate ligament rupture is three to five times more common in women, but neuromuscular training appears to decrease its incidence. Patellar tendon and hamstring grafts appear to be equally effective in anterior cruciate ligament reconstruction. Articular cartilage defects remain a significant problem, and the efficacy of treatments such as autologous chondrocyte implantation is still unclear.

Adolescent↗

Tenascin is associated with articular cartilage development.

The roles of tenascin in cartilage development and function remain unclear. Based on the observation that tenascin is particularly abundant at the epiphyseal extremities of developing cartilaginous models of long bones in chick and mouse embryo, we tested the hypothesis that tenascin is involved in articular cartilage development. Immunofluorescence analysis revealed that tenascin was first localized in the cell condensation region of Day 4 chick embryo limb buds, where the cartilaginous models form. With further development, tenascin gene expression became indeed restricted to the articular cap of the models. Tenascin persisted in the articular cartilage of postnatal chickens but appeared to decrease with age. The protein was also abundant in embryonic and adult tracheal cartilage rings which, like articular cartilage, persist throughout postnatal life. Similar patterns of tenascin expression were seen in mouse. Using monoclonal antibodies to avian tenascin variants, we found that the bulk of articular cartilage contained the shortest tenascin variant (Tn190), whereas the largest variant (Tn230) was present in tissues associated or interacting with articular cartilage (ligaments and meniscus). The protein and its mRNA, however, were undetectable in growth plate cartilage undergoing maturation and endochondral ossification. This inverse correlation between chondrocyte maturation and tenascin production was corroborated by the finding that tenascin gene expression decreased markedly during maturation of chondrocytes in culture and during formation of a secondary ossification center within the articular cap in vivo. Thus, tenascin is intimately associated with the development of articular cartilage and other permanent cartilages whereas absence or reduced amounts of this matrix protein characterize transient cartilages which undergo maturation and are replaced by bone.

Animals↗

[New developments in joint surgery].

The treatment of joint injuries has seen a marked development in the last years. The surgical trauma of articular reconstruction was reduced and our deeper understanding of the mechanism of connective tissue healing influenced the rehabilitation program after joint injuries significantly. Indirect soft-tissue sparing reduction techniques can be applied to most joint fractures and improved fixation techniques using intraoperative fluoroscopy or arthroscopy allow to avoid vast exposures of the joint. The process of ligament healing requires joint movement and a certain stress to the healing tissue in order to achieve optimum scar strength, stiffness and remodeling. Immobilisation thus should be avoided completely after ligament injuries and certain lesions can be treated non-operatively with a high success rate (MCL rupture, ankle sprain, elbow dislocation). In other injuries, surgery should stabilize the joint thus allowing functional rehabilitation (cruciate ligament tears, shoulder dislocation).

External Fixators↗

Polylactate-coated carbon fiber in extra-articular reconstruction of the unstable knee.

Fascia lata and carbon fiber were used in identical operations for the correction of a clearly defined knee instability in cases with a follow-up period of about one year. The early results suggest an improvement of the results in the carbon group, but free carbon has been found within the joint despite careful extra-articular implantation. The long-term consequences of this await evaluation.

Adult↗

Arthroscopically-assisted reduction of intra-articular fractures and soft tissue management of distal radius.

Arthroscopy was used to help to reduce intra-articular fractures of the distal radius and treat soft tissue injuries in 33 acute cases. The fractures were treated by reduction under arthroscopic control and percutaneous fixation either with or without external fixation. The triangular fibrocartilage complex (TFCC) was torn in 18 of 33 patients (54%). All tears were peripheral and were repaired with arthroscopic procedures. Scapholunate (SL) ligament injuries prevailed in six (18%) patients; most of them exhibited instability in the SL joint. They received SL ligament debrided and transfixed with K-wires. Four (12%) of the patients suffered lunotriquetral (LT) ligament injuries; three of them also received transfixation with K-wires. Six (18%) of the patients exhibited chondral fractures. All fractures healed without measurable incongruity of joint surface and at follow-up (24 to 36 months), 11 patients displayed excellent results and 22 patients displayed good results according to the Mayo modified wrist score.

Adult↗

The synergistic action of the capsule and the shoulder muscles.

The existence of a reflex arc from the glenohumeral capsule to several muscles crossing the shoulder joint was determined in the feline model. Three branches of the axillary nerve terminating in the glenohumeral capsule were identified and electrically stimulated with supramaximal, 100-microseconds pulses using bipolar hook electrodes. Stimulation of the anterior and the inferior axillary articular nerves elicited electromyographic activity in the biceps, subscapularis, supraspinatus, and infraspinatus muscles. Stimulation of the posterior axillary articular nerve elicited electromyographic activity in the acromiodeltoid muscle. Transection of the three articular nerves just distal to their emergence from the main axillary nerve resulted in the absence of any electromyographic activity in the muscles on stimulation, confirming the afferent nature of the articular branches. The time from application of the stimulus to the appearance of a response in the muscles varied from 2.7 msec in the biceps to 3.1 msec in the supraspinatus. The existence of a reflex arc from mechanoreceptors within the glenohumeral capsule to muscles crossing the joint confirms and extends the concept of synergism between the passive (ligaments) and active (muscles) restraints of the glenohumeral joint. This provides new information in orthopaedic sciences that has direct application in modification of surgical repairs and therapeutic modalities of shoulder injuries.

Animals↗

[Biomechanics of the shoulder--kinematics and intra-articular vacuum].

There being little skeletal stability, the shoulder joint must have a complex soft tissue anatomy in order to achieve sufficient stability in addition to good range of motion. The intra-articular vacuum provides some support for the joint structures in this function. Kinematic results obtained using a new spatial measuring systems (magnetic field system) have again quantified the clinical value of this vacuum phenomenon.

Biomechanical Phenomena↗

[The potentials of minimally invasive surgical measures in the knee joint].

The treatment of knee joint injuries has seen marked development in the last few years. The surgical trauma of intra-articular fracture reconstruction has been reduced significantly. Retrograde nailing, percutaneous plating and specific exposures to distal femur and proximal tibia fractures have been established. Percutaneous osteosynthesis controlled by arthroscopy or fluoroscopy is widely used for B-fractures of the tibial plateau. Injectable bone mineral cement adds to reduced trauma of surgical treatment of these fractures. In all knee ligament procedures, arthroscopy is obligatory for diagnosing and conducting meniscus surgery. Ligament reconstruction should be performed either arthroscopically or by a limited arthrotomy, the results being comparable at present.

Femoral Fractures↗

The anatomy of the scaphoid.

The scaphoid is a critical link in the mechanism of the carpus. Its complex shape allows it to participate in the kinematics of both the proximal and distal row. Because of its offset proximal and distal articular surfaces, it has a natural tendency to palmar-flex with longitudinal loading. Because of this, extension of the scaphoid places progressively increasing tension on the palmar cortex of the curved waist of the scaphoid. Excessive extension or ulnar deviation of the wrist, coupled with excessive loading, mechanically predisposes the scaphoid to fracture. This is especially true if the strong ligaments attaching to the scaphoid retain their integrity. When a fracture occurs proximal to the waist of the scaphoid, it is predisposed to displacement because of the opposing forces on the proximal [table: see text] and distal fragments as well as the distribution of ligament attachments. This, in turn, predisposes the proximal fragment to ischemic conditions because of the distal location of nutrient vessels and a retrograde intraosseous blood supply.

Biomechanical Phenomena↗

[The cubito-carpal region in gibbons].

As a continuation of our studies concerning the structure and fetal development of the human carpal articular disc (KAUER, 1968, 1975, 1976) we have investigated the disc-homologue in the Gibbon. For this purpose we have used the serial sectioned hand of a late-fetal specimen. The stratigraphical position of the os Daubentonii has been established comparing the situation in the Gibbon with that of the human ulno-carpal region. The homology presumed by others of the os Daubentonii with the cartilaginous primordium frequently found in the developing carpal articular disc in man, was found questionable. We have tried to give the os Daubentonii a functional interpretation as a sesamoid bone supporting the mechanical loaded pronation and supination of the hand in the Gibbon.

Animals↗

Anatomy of the human temporomandibular joint. An updated comprehensive review.

This article is an in-depth review of the current knowledge on human temporomandibular joints (TMJ's). All aspects of joint anatomy are described with emphasis on adaptability to biochemical stimuli throughout life. Each TMJ is a pressure-bearing compound double synovial joint. TMJ's are unique in having a movement not only controlled by the morphology of the joint per se but also by the dentition at the other end of the lever system. During life the temporal, condylar and discal articular surfaces undergo remodelling. The synovium is an important joint component which contributes to nourish and lubricate the avascular surfaces and has bactericidal properties. The joint capsule has privileged relationships anteriorly with the lateral pterygoid muscle. This muscle has two heads that show functionally reciprocal activation. The exact insertion and role of the superior head of the lateral pterygoid muscle remains controversial. The disc has a very low coefficient of friction and compensates for the lack of congruence between articular surfaces. Biomechanically it is stabilized between condyle and articular eminence by its thick rim which has special viscoelastic properties. Apart from the viscoelastic deformations the other important mechanism of disc stabilization seems to be related with the structure of some of the disc attachments.

Humans↗

Application of MR imaging for internal derangement of the knee (orthopedic surgeon' view).

Magnetic resonance imaging is a noninvasive imaging modality with clear contrast and superior spatial resolution. These characteristics are especially useful for detecting pathology of the soft tissue of the knee joint, such as the menisci, ligaments and articular cartilage, which are difficult to diagnose using plain X-ray examination. MRI has become one of the first choice diagnostic modalities for the internal derangement of the knee joint, and is generally replacing some invasive arthrographic or arthroscopic examination. Pathology of the articular cartilage cannot yet be depicted clearly by MRI. We expect further development of the spatial resolution of MRI to make possible the detection of chondral lesions more clearly and precisely in the near future.

Adult↗

Bone-block iliotibial-band transfer for anterior cruciate insufficiency.

The anterior distal part of the iliotibial trace with attached bone block from Gerdy's tubercle was used as an intra-articular graft fixed by a screw to the tibia to control anterior instability (otherwise known as anterior, anteromedial, or anterolateral laxity) in twenty-four knees which were followed for two to four years. Concomitant single-plane 2+ to 4+ medial instability was present in eleven knees and was treated in five of them by simple immobilization, by imbrication of the medial collateral ligament, or by the Vigliani procedure. At follow-up, stability was improved and the result was rated good or excellent in twenty-one (88 per cent) of the twenty-four knees. The operation is applicable to the majority of chronic laxities of the knee and, because no immobilization is necessary, the postoperative care is much simplified and the rehabilitation time is much shorter. The procedure is contraindicated where there is posterior or single-plane lateral laxity.

Adolescent↗

The significance of chondromalacic changes on the patella.

A total of 500 arthroscopies were performed in a 2-year period, with special reference made to the patellofemoral joint. In those with pain thought to be arising from this joint, 63% had chondromalacic changes on the posterior surface of the patella compared with a 45% incidence in those with meniscal pathological findings at arthroscopy. This study demonstrates that those with patellofemoral pain do not always have patellar articular changes, and patellar pathology is often asymptomatic. As a result, treatment directed at these lesions must be used with great caution.

Adult↗

Glenohumeral stability. Biomechanical properties of passive and active stabilizers.

The shoulder is characterized foremost by its mobility and large range of motion. The glenohumeral joint is notable for its relative lack of bony constraint, relying heavily on the congruent articulating surfaces and surrounding soft tissue envelope for static and dynamic stability. Effective function in the articulation is achieved by a complex interaction between the various articular and soft tissue restraints. The rotator cuff muscles center the humeral head in the congruent glenoid fossa through the midrange of motion, when the capsuloligamentous structures are lax. However, incongruent joints, especially in positions of loading asymmetry (in external rotation), have larger translations that occur at the extremes of motion. Excessive translations are then effectively restricted by the mechanical properties of the inferior glenohumeral ligament. When the capsule is tightened anteriorly it results in an anterior tether and causes an associated posterior shift in contact on the glenoid. The posterior migration of the humeral head center and glenohumeral contact are again more pronounced in shoulders with reduced congruence. Additional studies of normal motion in different planes, the effects of rotator cuff pathology and dysfunction on the kinematics of the joint, proprioception of the capsule, and biomechanical tests of the inferior glenohumeral ligament and other components of the joint capsule at strain rates associated with injury, need to be conducted to understand the specifics of normal shoulder function and the pathophysiologic processes that occur during shoulder degeneration.

Biomechanical Phenomena↗

The torn meniscus, the torn anterior cruciate ligament, and their relationship to degenerative joint disease.

A retrospective review of 350 knees was carried out to determine the effect, if any, of a torn meniscus and a torn anterior cruciate ligament on the articular surfaces of the knee. There were no professional or college athletes in this group, although a few were enthusiastic sandlot-type players. The time interval between injury and surgery was known, as was the state of the articular surfaces, which were graded from 1 to 4. As the time interval between injury and surgery increased, so did the incidence of lesions of the articular surfaces, although in most cases these lesions were quite minor. On the basis of this and other studies, it was concluded that the torn meniscus does not pose a significant threat to the integrity of the articular cartilage; this was also true in those patients in whom the anterior cruciate ligament was torn.

Cartilage, Articular↗

Assessment of intra-articular volume of the wrist: a comparative study between CT-arthrography and dissection.

The aim of this study was to compare the intra-articular volumes of the wrist's joint measured by CT-arthrography and by dissection on ten cadavers. A good correlation was found between CT-arthrography and dissection in the assessment of the intra-articular volume of both wrist joints. A volume of 1.34 (+/-0.46) milliliter and 0.97 (+/-0.32) milliliter were found by Ct-arthrography for the radiocarpal and midcarpal joints, respectively. Dissection of the same wrists gives a volume of 1.24 (+/-0.33) and 0.90 (+/-0.21) for the radiocarpal and midcarpal joints, respectively. The knowledge of normal wrist-joint volume is a major prerequisite to evaluate carpal instability without ligaments' tears. We believe that CT-arthrography could be helpful in evaluating patients with suspected carpal instability.

Arthrography↗