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Results for “Condylar position”

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PubMed1989

Effect of knee component alignment on tibial load distribution with clinical correlation.

To determine ideal alignment and component placement of total knee prostheses, Kinematic (K) and total condylar (TC) devices were physiologically loaded and interface forces were measured. Laboratory observations were correlated with clinical (roentgenographic) findings. Asymmetric loading of the tibial component has been proposed as causing loosening and radiolucent lines. Misalignment of components is one factor that affects load sharing by bone under the medial and lateral regions of the tibial plateau. Tibial components of K and TC prostheses were inserted without cement into the cut surfaces of artificial tibiae. The mating femoral condylar components were mounted. The tibial and femoral components were individually positioned at 0 degrees (horizontal) and at certain angles of varus and valgus. Pressure-sensitive film was placed between the tibial component and the artificial tibia. A vertical load of 1500 N was used. The experiment was replicated twice. The percentages of the load on the medial and lateral regions of the tibial plateau were calculated from quantitative image analysis of the pressure patterns on the film. Roentgenograms from 532 K and 21 TC patients were examined to determine the orientations of the condylar and tibial components and the presence of radiolucent lines around the tibial component. An even distribution (ideal alignment) of load on the medial and lateral regions of the K tibial component occurred at 9 degrees of valgus tilt of the femoral component and 2 degrees of varus tilt of the tibial component and for the TC at 7 degrees valgus and 0 degrees varus. Misalignment by 5 degrees yielded a 7% change in the load distribution under the K plateau and a 40% change for the TC prosthesis; a 10 degrees misalignment produced changes of 34% and 62% for the K and TC, respectively. Small variations in clinical knee alignment produced the same percentage of radiolucent lines for each alignment group. The location of radiolucent lines was distributed among the medial, lateral, and both tibial plateaus regardless of knee alignment, although there were more medial reactions overall. The smallest incidence (8%) of radiolucent lines occurred with the K prosthesis at 7 degrees of knee valgus, the femoral component placed at 9 degrees valgus, and the tibial component at 2 degrees varus. This correlated with the ideal bench-test findings for the K device.

Humans↗

PubMed2003

Measurement of condylar motion: a plea for the use of the condylar kinematic centre.

In this study, a plea is given for the use of the kinematic centre in studies of the kinematics of the human temporomandibular condyle. The concept of the kinematic centre is based upon the assumption that the movements of the condyle-disc complex within the temporomandibular joint can reasonably well be described by those of a ball-shaped condyle-disc complex. The kinematic centre is then the centre of the sphere. Its movement traces have the advantage that they are smooth and have a good reproducibility between consecutive movements. Moreover, the open and close traces are just a few tenths of a millimetre apart and show no crossings. This makes the kinematic centre a suitable choice in order to avoid false-positive diagnoses in the study of internal derangements by means of condylar movement recordings. However, the kinematic centre has the disadvantage that the mandibular movements have to be recorded by rather complicated six degrees of freedom recording equipment and that the exploration algorithm for its location may sometimes have difficulties in finding the right location.

Biomechanical Phenomena↗

PubMed2002

Mandibular condylar growth alterations after unilateral partial facial paralysis: an experimental study in the rabbit.

In a previous study in the rabbit, the authors defined the macroscopic growth alterations after unilateral partial facial paralysis. Dry skull measurements revealed a reduced premaxillary, maxillary, mandibular, and anterior corpus length with a simultaneous increase in mandibular ramal height on the paralyzed side. The authors hypothesize that these mandibular growth alterations are, among others, caused by alterations in condylar growth activity and that an altered occlusal relationship may be involved in the adaptive condylar growth response after facial paralysis.A total of 84 New Zealand White rabbits were used for this study. The animals were randomly assigned to either a control group that was not operated on (n = 28), a group that underwent a sham-operation (n = 28), or an experimental group (n = 28). In the sham-operation group, the facial nerve was dissected as in the experimental group but was left intact. In the experimental group, a left-side partial facial paralysis involving the midfacial muscles was induced by an operation at the age of 12 days. After different follow-up time intervals of 3.5, 7, 14, 21, 28, 42, and 56 days, four control, four sham-operation, and four experimental animals (all randomly selected) were killed for histomorphometric measurements of the left control and sham condyles and the left-side and right-side experimental condyles. No significant differences between the control and sham-operation groups were found. The other results revealed that shortly after the paralysis in the experimental group, as compared with the controls, a decrease in condylar growth activity was seen before a catch-up increase in activity, as expressed by the time-sequenced decrease and increase in the height of the functional and hypertrophic chondroblast layer. The response on the right side was analogous, though less intense. It is suggested that the mandibular ramal growth alterations might be the result of a chain of adaptations involving the lateral pterygoid muscle and the condylar growth activity. The unilaterally restricted length increment of the maxillary snout, as a result of the loss of tensile forces caused by paralysis of the midfacial musculature, necessitated an adaptation in the position of the mandible to maintain a normal occlusal relationship. Subsequently, the function of muscles involved or influenced by an altered mandibular position, such as the lateral pterygoid muscle, were changed. These altered muscle activities induced condylar growth adaptations, which in turn explained the alterations in mandibular ramal growth.

Animals↗

PubMed2001

The development of articular cartilage: evidence for an appositional growth mechanism.

It is well-established that cartilage grows by a combination of matrix secretion, cell hypertrophy and cell proliferation. The extent to which this growth is by appositional, as opposed to interstitial mechanisms, however, remains unclear. Using the knee joints of the marsupial Monodelphis domestica to study cartilage growth, we have combined an immunohistochemical study of the TGF-beta family of cartilage growth and differentiation factors between 30 days postpartum to 8 months, together with a stereological analysis of cartilage morphology during growth. Furthermore, to gain an insight into the generation of the characteristic zones within cartilage, we have examined the effects of intra-articular administration of bromodeoxyuridine, an agent that is incorporated into DNA during cell division and blocks further cell cycling. During early growth, TGF-beta2 and -beta3 were widely expressed but TGF-beta1 was less so. After the formation of the secondary centre of ossification, all isoforms became more restricted to the upper half of the tissue depth and their distribution was similar to that previously described for IGFs, and PCNA-positive cells. Stereological analysis of tissue sections from the femoral condylar cartilage at 3 and 6 months showed that there was a 17% increase in total cartilage volume but a 31% decrease in cell density on a unit volume basis. Finally, cell-cycle perturbation with BrDU, which was injected into the knee joints of 3-month-old animals and analysed 1 and 4 months post-injection, revealed that the chondrocytes occupying the transitional zone were depleted 1 month post-injection, resulting in thinning of the articular cartilage. This effect was reversed 4 months post-injection. Immunohistochemical analysis revealed that BrDU-treatment altered the expression patterns of all TGF-beta isoforms, with a marked reduction in labelling of TGF-beta1 and -beta3 isoforms in the upper half of the cartilage depth. Overall, the data lends further support to the notion of articular cartilage growing by apposition from the articular surface rather than by interstitial mechanisms.

Animals↗

PubMed1985

Endochondral ossification of the condyle in rats on a strontium or low-calcium diet.

The mechanism of abnormal endochondral ossification induced by administration of strontium salts was studied in the mandibular condyles of rats by radiographic, histologic, and histochemical methods. It was shown by radiographic and histologic findings that ossification of the mandibular ramus was clearly inhibited in rats fed a low-calcium diet and rats fed a strontium diet. The change in appearance of the mandibular condyles of the rats fed strontium was more severe than that in those fed low amounts of calcium. From the histochemical findings, it was suggested that the metabolic dysfunction of chondroitin sulfate, periodic acid-Schiff positive materials, and collagen in the hypertrophic zone of the condylar cartilage (or in the part corresponding to trabecular bone of the mandibular ramus) was one factor inhibiting normal endochondral ossification.

Animals↗

PubMed2000

A study on the mandibular movement of anterior openbite patients.

The purpose of this study was to compare the mandibular movements of anterior openbite patients using those of normal bite (angle class I) patients, to ascertain which components of mandibular movement are different in the two groups, and to use this information for occlusal treatment. The Saphon Visi-trainer Model 3 and the Denar Pantronic were used to record mandibular movement and a Pantronic survey was performed using an arbitrary hinge axis, according to manufacturer's instructions. The subjects were 43 adults and included 28 subjects presenting with acceptable normal occlusion (angle class I) with no sign of TM dysfunction syndrome (TMD) and 15 subjects with anterior openbite with no anterior guidance. In the anterior openbite group, the average anterior and lateral condylar inclination, maximum opening and the distance between the intercuspal position with retruded contact position distance (anterior-posterior) were significantly lower than normal. The results suggest that in openbite patients the condyle inclination is flatter and the function of the TMJ is more restricted than in the mandibular movements of the normal group. It is hoped that these results will be useful for the correction of the anterior openbite condition.

Adolescent↗

PubMed2002

An index for analysing the stability of lateral excursions.

Five lateral excursions on both left and right sides of 20 healthy subjects were recorded by Gnatho-hexagraph, which was an opto-electronic system with six degrees of freedom. The incisor point, the working condylar point (WCP) and the balancing condylar point (BCP) were analysed. When the incisor point moved 1, 2, 3, 4, 5 mm on its path, the incisor point and corresponding condylar points were analysed. The linear distances from the intercuspal position (ICP) to each analysed point at each analysed position were calculated as Linear distance. The distance between five lateral excursions in x, y, z, space coordinates at each analysed position of three analysed points were calculated as Dx, y, z, s. To evaluate the stability of lateral excursions, the Index S was defined as the equation (S=D/Linear distance * 100) and calculated. From the result of Index S, the WCP showed significantly less stability than the other two analysed points (P < 0.05). The incisor point showed best stability, especially in upper-lower direction. The BCP also showed good stability. Index S revealed the characteristic movement in x, y, z, space coordinates at each analysed point and it showed clearly the stability of lateral excursions.

Adolescent↗

PubMed2002

A study of the movements of the human temporomandibular joint complex in the cadaver.

The objective of this study was to define the movements in the sagittal plane of the articular disk relative to the temporal bone and the mandibular condyle respectively, on jaw-opening in the absence of loads. Four temporomandibular joints from two human cadavers were used as materials in the study. Ten steel needles were placed in the lateral plane. Lateral photographs were taken of the articular area in different mandibular positions. OXY reference systems were adapted to the temporal and condylar points. The movements of the disk relative to the temporal bone are statistically different from those relative to the condyle. These findings are consistent with the new concept that the mandible joins the skull through two Temporomandibular Joint Complexes (TMJCs), one on each side and each one made up of a reciprocally fitting temporodiskal joint and a disko-condyle of the condylar type.

Algorithms↗

PubMed2006

Influence of sex hormone disturbances on the internal structure of the mandible in newborn mice.

It has not yet been clarified how sex hormones affect craniofacial bone development immediately after birth. The purpose of this study was to examine the effects of sex hormone deficiency on craniofacial bone development immediately after birth, in terms of the internal structure of the mandible in newborn mice with orchiectomy (ORX) and ovariectomy (OVX). ORX, OVX and a sham-operation were performed on 40 five-day-old C57BL/6J mice. Eight weeks after surgery, each mandible was subjected to histomorphometric analysis of trabecular (Tr) and cortical (Ct) bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT). In the experimental groups, a significant reduction in BMD was found in comparison with the control groups. In histomorphometric analysis, the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the condyle and the thickness of the condylar cartilage layer was significantly greater in the experimental mice than in the controls. Trabecular bone volume of the condyle measured on azocarmine-aniline blue (AZAN) sections was significantly less in the experimental mice than in the controls. These results indicate that mandibular growth is inhibited by sex hormone disturbances and the relevant internal structures changed. The findings show that sex hormones are one of the key determinants of mandibular growth and development immediately after birth.

Acid Phosphatase↗

PubMed2000

Craniofacial growth.

Craniofacial growth represents a complex enlargement and differentiation of hard and soft tissues, characterized by cephalocaudal and allometric patterns. The cranial base matures earlier than the face and is used cephalometrically as a relatively stable reference area. The maxilla, although intimately associated with the cranium, exhibits some independent growth, particularly in the vertical dimension. The mandible, hanging in a sling of muscles and articulating only at the temporomandibular fossae and with the opposing dentition, is purportedly able to adapt its shape and position in space to some extent as a function of condylar growth.

Adult↗

PubMed1975

[Arthroplasty of the knee. Prosthesis without uni- or bicondylar hinge].

The prosthesis has two components. The femoral component is metallic surfacing the condyle and a tibial plateau in polyethylene replaces the original one. The prosthesis can be uni or bi-condylar. Operative technique has to be very precise and the position of the prosthesis needs accuracy. The advantages are: minimal bone resection, small implant harmonic action with the knee joint as a whole. 20 patients with I8 months follow up are reviewed, problems are infections and pain in the patello-femoral joint. The results on pain and walking are good. Stability depends on accurate indications.

Aged↗

PubMed2002

The influence of altered occlusal guidance on condylar displacement.

This study investigated mandibular displacement and masticatory muscle activity during clenching in lateral occlusal position in relation to the lateral occlusal pattern. Twenty healthy human subjects (mean = 26.5 years) volunteered for this study. Metallic occlusal overlays were fabricated for the lower working side canine to second molar and non-working side second molar in order to simulate a canine protected occlusion, group function occlusion and bilateral balanced occlusion (balancing contact). Three-dimensional displacements of the bilateral condyle and electromyography (EMG) activities in the bilateral masseter, anterior and posterior temporalis were recorded during maximal clenching. The experimental occlusal pattern was revealed to have statistically significant effects on both condylar displacement and EMG activity (P < 0.001 and P < 0.001, respectively). When compared to the simulated group function occlusion, the simulated canine protected occlusion and balancing contact caused statistically significant smaller superior displacements of the non-working side condyle, which suggests that they may result in reduced temporomandibular joint (TMJ) loading. Furthermore, the simulated canine protected occlusion was associated with the lowest EMG activity, which suggests that this occlusal pattern has the capacity to reduce the level of parafunctional activity.

Adult↗

PubMed1977

Condylar fractures of the mandible. I. Classification and relation to age, occlusion, and concomitant injuries of teeth and teeth-supporting structures, and fractures of the mandibular body.

In 123 individuals, 138 fractures of the mandibular condyle were classified with respect to fracture level, dislocation at the fracture level, and condylar head relation to the articular fossa. The age of the patient and the location of the most distal occlusal contact were recorded as well as teeth injuries and concomitant fractures of the mandibular body. The position of the most distal occlusal contact did not influence the dislocation of the condylar fragment. Teeth injuries such as fractures and luxation were found to be associated with condylar head or neck fractures, whereas the concomitant fractures of the mandibular body were mostly seen with the subcondylar fractures. Teeth injuries as well as concomitant fractures of the mandibular body were found more frequently in patients with bilateral than unilateral condylar fractures. Fractures of teeth in the molar and bicuspid regions were most frequent on the condylar fracture side, while the concomitant fractures of the mandibular body were located to the contralateral side. Medial angulation of the condylar fragment with lateral override at the fracture level was the typical fracture in adults, and angulation without override the characteristic fracture in growing individuals. Medical override occurred both in children and in adults and seemed to be the result of more severe trauma to the chin.

Accidents↗

PubMed1991

[Protrusive condyle path in edentulous patients].

The inclinations of condyle path of 32 edentulous patients were measured by taking protrusive relation record at the protrusive positions of 2, 4, 6, and 8 mm. The relations between the condylar shift and the protrusive distance were analysed. It was found that the inclination of condyle path was varied with individual, sex and protrusive distance. The shape of protrusive condyle path was like a section of parabola curved forward and downward. The results demonstrate that a small free gliding area in centric occlusion is necessary in complete dentures to fit the physiological movement of temporomandibular joints. The position of rotation center of protrusive movement requires further study.

Aged↗

PubMed1992

Rigid internal fixation and the effects on the temporomandibular joint and masticatory system: a prospective study.

A prospective study of 22 patients who underwent a bilateral sagittal osteotomy to advance the mandible and subsequent rigid internal fixation, were examined for signs and symptoms of temporomandibular joint (TMJ) pain and masticatory dysfunction. A modified Helkimo index was used to analyze the anamnestic, clinical, and occlusal data. In addition, 12 of the cases chosen at random were mounted on a semiadjustable (SAM2) articulator and analyzed with the mandibular position indicator (MPI) to determine the amount and the direction of condylar displacement postoperatively. Anamnestic dysfunction decreased because of a reported decrease in muscular pain, joint noise, headache frequency, and parafunctional habits postoperatively. Clinical dysfunction remained unchanged, with a decrease in muscular soreness but with an increased incidence of joint clicking of 7%. The increased incidence of temporomandibular joint pain postoperatively was 4%. Increase in clinical dysfunction was most often seen in women and older patients. Occlusal dysfunction decreased, with the majority of interferences remaining after surgery as a result of insufficient lingual crown torque of the maxillary buccal segments. Occlusion is thought to have played only a minor role in temporomandibular joint and masticatory dysfunction. Reduction in range of motion was 10%, indicating the added benefit of early mobilization with rigid internal fixation procedures. The MPI study found the condyles inferiorly or inferoposteriorly displaced less than 1 mm from their preoperative position. These findings suggest that rigid internal fixation had no adverse effects on the temporomandibular and masticatory system. The variable responses and results can be attributed, at least in part, to the heterogenous population of patients studied and the variations in surgical techniques employed.

Adolescent↗

PubMed1977

Condylar translation and the function of the superficial masseter muscle in the rhesus monkey (M. mulatta).

The relationship between translation of the mandibular condyle during symmetrical mandibular rotation, i.e., symmetrical jaw depression and elevation, and the function of the superficial masseter muscle was examined in light of relative torque and the length-tension relationship for muscle. Lateral cephalograms of live adult rhesus monkeys (Macaca mulatta) were analyzed using two models: (1) Model A, normal symmetrical jaw rotation accompanied by condylar translation; and (2) Model B, mandibular rotation about an axis fixed at the position of the condyles during centric occlusion. The decrease in relative torque and the excursion of the superficial masseter at mouth-open positions are significantly greater in Model B than in Model A. Symmetrical rotation of the jaw about a fixed axis would result in a 35% greater loss of maximum producible tension at maximum gape than rotation associated with condylar translation. These results suggest that condylar translation during mandibular depression and elevation functions to minimize reduction in relative torque and excursion of superficial masseter muscle, thereby maintaining optimal potential for exerting maximum tension during jaw closure.

Animals↗

PubMed2006

Femoral component rotation in mobile-bearing total knee arthroplasty.

The surgical technique utilized for the LCS mobile-bearing since 1977 has been a tibial cut first method which requires determination of femoral rotation with tension spacing. We evaluated 38 randomly selected mobile-bearing TKA in which this technique was utilized. All cases had satisfactory clinical results. Spiral computed tomography scans measured the posterior condylar angle which is the angle of the femoral component posterior condyles in relation to the surgical transepicondylar axis. The mean femoral component alignment was 0.3 degrees of internal rotation to the transepicondylar axis (S.D.=2.2 degrees ; range=6 degrees internal to 4 degrees external). Four cases (10%) were outside of 3 degrees from the TEA. Lateral patellar tilt and subluxation was identified in one female who had a femoral component position of 5 degrees internal rotation. In 90% of cases, the posterior condylar angle was within 3 degrees of the surgical transepicondylar axis which is regarded as the functional ideal for conventional methods.

Aged↗

PubMed2001

Resorption of the temporomandibular condylar bone according to subtypes of juvenile chronic arthritis.

OBJECTIVE: To evaluate the relative impact of sex, type of onset, course of disease, age at onset, duration of disease and status of HLA-B27, antinuclear antibodies (ANA), and rheumatoid factor on the risk of developing a condylar erosion. METHODS: Condylar changes of the temporomandibular joint (TMJ) were diagnosed on orthopantomograms from 169 consecutive patients with juvenile chronic arthritis (JCA). A multiple regression analysis was applied to establish the relative weight of the independent variables affecting the severity of the condylar erosion. RESULTS: It was found that 62.1% of the patients exhibited condylar resorption. The highest prevalence was seen in children with a polyarticular onset or course of disease and early age at onset and severe resorption was also frequent in these groups. Patients with positive ANA also had a high prevalence but with a mild degree of resorption. In contrast, HLA-B27 positive patients had a lower risk of TMJ involvement and resorptive changes of the condyle. CONCLUSION: Polyarticular and early onset arthritis are associated with a high risk for TMJ involvement and a severe condylar bone loss can be expected. ANA positive patients have a high prevalence, and B27 positive patients have a low prevalence of TMJ arthritis but in both subgroups, the outcome of the bone resorptive process is mild.

Adolescent↗