Some physiological aspects of bone marrow pressure.

An investigation was made into some of the hemodynamic properties of bone. The parameters studied were bone marrow and medullary venous pressures. The resting level and changes in the two pressures were measured under autoperfusion and constant-flow perfusion conditions. Changes were induced either by drugs or by alteration in blood flow. Marrow pressure was measured with a new tonometric technique. A specially constructed miniature pressure transducer was utilized as the tonometer. Trauma-induced hemorrhage of the marrow was avoided. The marrow pressure was measured across an intact endosteal membrane. The pressure of the normal bone marrow and the medullary venous pressure in the anesthetized dog were nearly equal, approximately twenty millimeters of mercury and about 17 per cent of systemic blood pressure. These values were found whether measured simultaneously or separately in comparable groups of dogs under a variety of conditions. Induced changes in the two pressures produced either by changes in perfusion rate or by drugs were also nearly equal and in the same direction.

Internal derangements of the temporomandibular joint. Pathological variations.

A retrospective analysis of 540 operated cases (740 joints) of internal derangements of the temporomandibular joint was carried out. Observations of this patient population provided the basis for describing pathological variations of internal derangements. Radiologic studies, including tomograms and arthrograms or magnetic resonance scans, and surgical/pathological findings were correlated with clinical data in each case. It was found that clinical manifestations varied in a characteristic way and were directly related to the degree of pathological change and time course. Various stages of internal derangements were identified. Pathophysiological mechanisms responsible for the observed changes, as well as clinical signs and symptoms and causal factors, were discussed. Internal derangements are organic lesions that appear to be progressive and are probably of traumatic origin. The view is given that internal derangements represent the basic pathological entity responsible for clinical manifestations of what has been known as the temporomandibular joint pain-dysfunction syndrome or similarly described conditions. Effective clinical management takes on new importance because progression to advanced degenerative states may occur.

Surgical treatment of internal derangements of the temporomandibular joint. A long-term study.

A long-term surgical follow-up study of 176 patients (211 joints) with documented internal derangements of the temporomandibular joint was carried out. Arthrograms and tomograms were used in all cases. Forty of the patients (49 joints) were nonsurgical control patients. Diagnostic staging of the cases was accomplished as previously published. A clinical/radiologic assessment index was derived, which included seven measured parameters. Surgical patients, grouped by diagnostic stages and selected operations, were compared with each other and with control patients over the follow-up period (average, 8.1 years; range, 5 to 14 years). The surgical procedures included meniscectomy, reconstructive arthroplasty, and arthroplasty with temporary Silastic (Dow Corning Wright, Arlington, Tenn) implant. The overall success rate for surgical cases with all stages and procedures was 93.8%. In contrast, the control group demonstrated significant clinical and radiographic progression. The surgical results were stage dependent for the same operative procedure. Significantly better success rates were obtained in early-stage cases (96.9%) than in late-stage cases (89.4%). With respect to comparison of operative procedures, it was found that reconstructive arthroplasty provided results superior to those of meniscectomy. There was no significant difference between results obtained by meniscectomy and those by arthroplasty with a temporary Silastic implant. Long-term stability was excellent in most cases. Follow-up radiographic changes for the surgical group were less than expected. On the other hand, radiographic analysis of the control group demonstrated progressive degenerative changes in 73.5% of cases. Complications over the entire study were rare. It was concluded that surgery can provide successful long-term results in the treatment of internal derangements.

Temporomandibular joint imaging. Practical application of available technology.

Clinical afflictions of the temporomandibular joint (TMJ) are common, but TMJ afflictions remain one of the most poorly understood and controversial areas of clinical practice. Theories of TMJ pathophysiology, diagnosis, treatment, and patient disposition abound. Many afflicted patients have undergone expensive, protracted, and fruitless therapeutic endeavors, many of which are without scientific basis, causing many health insurers to exclude evaluation and treatment of TMJ disorders from coverage. Medical imaging has a central role in establishing a correct diagnosis. Available imaging procedures include roentgenography, arthrography, videofluoroscopy, magnetic resonance imaging, and computed tomography.

Three-dimensional computed tomography in maxillofacial surgical planning.

Fifty-four maxillofacial three-dimensional computed tomographic examinations were performed during a 12-month period for the purpose of surgical planning. Pathologic entities in the series included trauma, neoplasia, cleft palate, and other developmental anomalies. Computer-assisted mandibular disarticulation was performed routinely after each study to permit direct viewing of the mandible or maxilla in isolation. Three-dimensional computed tomography is a useful technique for maxillofacial surgical planning.

Mandibular retrusion, temporomandibular joint derangement, and orthognathic surgery planning.

One-hundred consecutive orthognathic surgery candidates with mandibular retrusion were selected for retrospective analysis. Patients had undergone imaging studies that included magnetic resonance imaging (MRI) of both temporomandibular joints to assess the presence or absence, stage, and activity of suspected internal derangement(s). Patients were divided into stable and unstable deformity groups based on the presence or absence of change in their facial contour and/or occlusal disturbances in the 24 months prior to evaluation. Each of the 58 unstable and 30 of 42 stable patients were found to have internal derangements of at least one temporomandibular joint. The degree of joint degeneration directly paralleled the severity of retrognathia in most cases. We concluded that temporomandibular joint internal derangement is common in cases of mandibular retrusion and leads to the facial morphology in a high percentage of patients. Preoperative temporomandibular joint imaging with MRI is recommended prior to orthognathic surgical correction of retrognathic deformities.

Temporomandibular joint inflammation: comparison of MR fast scanning with T1- and T2-weighted imaging techniques.

One hundred painful temporomandibular joints in 100 patients were studied with high-field, surface-coil MR imaging. Partial flip angle or GRASS (gradient-recalled acquisition in steady state) and either T1-weighted or spin-echo long TR/short-long TE imaging techniques were used to assess the relative sensitivity and accuracy of these techniques in detecting joint fluid. Intraarticular fluid, interpreted to represent joint effusion, was observed in 88 of the 100 painful joints scanned. GRASS scans were obtained with the mouth closed, partially opened, and fully opened; T1-weighted and spin-echo images were obtained only with the mouth closed. Long TR/long TE spin-echo images were the most sensitive to fluid detection within the joint spaces. GRASS images were highly sensitive to intraarticular fluid, although the thicker scan section and local artifacts associated with these techniques resulted in lower accuracy compared with the spin-echo long TR/long TE images. Joint fluid was directly observed in many of the 28 joints operated on from the series, and two of two joints were successfully aspirated. Osteochondritis dissecans and avascular necrosis are best demonstrated and staged with a combination of short TR/short TE and long TR/long TE weighted images, although a spin-echo long TR/short and long TE pulse sequence is more practical for this purpose. We recommend long TR/short and long TE spin-echo closed-mouth sagittal images combined with GRASS closed- and open-mouth views whenever inflammatory temporomandibular joint disease is suspected.

Facial pain, headache, and temporomandibular joint inflammation.

We studied one hundred patients with suspected temporomandibular joint (TMJ) arthropathy in whom 64 also complained of headache and/or facial pain, using high field surface coil magnetic resonance (MR) imaging, and found that headache and facial pain are commonly observed in association with inflammatory arthropathy of the TMJ. Each patient complained of pain and/or tenderness localized to the immediate vicinity of at least one TMJ. Pathologic joint effusion was demonstrated by MR in 88 of the painful joints studied. Significant meniscus displacement, with or without meniscus deformity and alteration of intrinsic signal intensity was present in 94 of the 100 painful joints examined. Fascial inflammation and atrophy of the ipsilateral muscles of mastication were observed occasionally with painful joints. There were no mechanical TMJ symptoms, such as joint clicking, crepitus or locking in 14 internally deranged and painful joints, 12 of which exhibited joint effusion and local inflammation. At least 80 patients described occlusal changes within 12 months of imaging. 28 of the pathologic joints in the series underwent subsequent meniscectomy, including routine histologic evaluation of surgical material. We conclude that internal derangement and inflammation of the TMJ should be considered in patients with unexplained headache and/or facial pain, even if mechanical TMJ symptoms are absent.

Pediatric internal derangements of the temporomandibular joint: effect on facial development.

To evaluate the relationship between internal derangement(s) of the temporomandibular joint(s) (TMJ) and disturbed facial skeleton growth (dysmorphogenesis), 128 consecutive children (103 girls, 25 boys), who were 14 years of age or younger and had undergone combined radiographic and magnetic resonance (MR) imaging studies of both TMJs, were retrospectively analyzed. Imaging studies had been performed to investigate suspected TMJ derangement because of symptoms that included, either individually or in various combinations, pain, mechanical TMJ dysfunction, and facial skeleton abnormalities, such as mandibular deficiency (particularly retrognathia) and lower facial (mandibular) asymmetry, manifested by chin deviation from the midline. Of these patients, 112 were found to have at least one internally deranged TMJ on imaging studies; in 85 patients, both TMJs were abnormal. Of the 60 retrognathic patients 56 were found to have TMJ derangement, generally bilateral and often of advanced stage. In cases of lower facial asymmetry, the chin was uniformly deviated toward the smaller or more degenerated TMJ. Both TMJs were normal in 16 patients, most of whom had normal facial structure. We conclude that TMJ derangements are both common in children and may contribute to the development of retrognathia, with or without asymmetry, in many cases.

MR of osteochondritis dissecans and avascular necrosis of the mandibular condyle.

We studied 40 patients exhibiting radiologic changes of either osteochondritis dissecans (OCD) or avascular necrosis (AVN) involving the mandibular condyle to evaluate the structural changes associated with these lesions when using high-field-strength MR imaging. Various clinical indications for imaging each patient with routine radiography, tomography, and surface-coil MR included headache, temporomandibular joint (TMJ) and/or ilsilateral facial pain, joint crepitus, clicking, locking, and either recently acquired or changing (unstable) occlusal disorder. Radiologic findings included alterations in condyle morphology and MR signal characteristics compatible with either OCD or AVN or, in some cases, both. Previous nonsurgical mandibular trauma was temporally related to the onset of symptoms in eight patients. Five patients exhibiting either unilateral or bilateral AVN involving the condyles and condylar necks had undergone previous orthognathic surgery, including sagittal split mandibular osteotomies followed by intermaxillary fixation. One patient exhibiting condylar AVN with articular surface collapse and osseous destruction had undergone previous TMJ meniscectomy followed by insertion of a permanent Proplast implant. Thirty-one of 34 patients with no prior surgery and MR changes of condylar OCD/AVN had associated internal derangement of the TMJ meniscus. There was surgical confirmation of findings in 10 joints. We assert that OCD and AVN are relatively common, clinically significant lesions of the mandibular condyle often associated with preexisting internal derangement of the temporomandibular joint.

Temporomandibular joint: MR imaging of internal derangements and postoperative changes.

Nineteen abnormal temporomandibular joints (TMJs) imaged with high-field-strength surface-coil MR are presented to illustrate specific changes associated with disk derangement, trauma, and previous surgery. Cases were selected from a series of 248 TMJ MR studies in 144 patients (9-68 year old, 130 females and 14 males) performed during a 5-month period. Surgical findings were available for correlation in 44 of the 248 joints studied. Increased signal caused by myxoid degeneration within the degenerating meniscus was seen, as were pathologic changes including atrophy, fibrosis, and contracture of masticatory muscles occurring with internal derangements. Advantages and limitations of MR are discussed with reference to arthrography and videofluoroscopy. High-resolution and partial-flip-angle images of a normal joint are provided for comparison. In most clinical circumstances, MR is the procedure of choice when examining the TMJ, because it provides contrast resolution of soft-tissue structures superior to that of conventional imaging techniques.

Permanent Proplast temporomandibular joint implants: MR imaging of destructive complications.

We studied the radiologic and pathologic changes in 30 patients (34 joints) in which there were locally destructive bone and soft-tissue complications associated with previously inserted permanent temporomandibular joint (TMJ) Proplast-Teflon implants. The cases were selected as representative examples of patients with failed Proplast interpositional arthroplasty, in whom images of the TMJ were obtained with conventional radiography, tomography, and MR, and in whom both surgical and histologic findings were available. Clinical indications for imaging included joint pain, restricted joint motion, crepitus, preauricular swelling, regional lymphadenopathy, malocclusion either acquired or changed since implant surgery, and facial deformity. Surgery was then performed for the purposes of implant retrieval and joint debridement because of destructive soft-tissue and osseous changes observed from the imaging analysis in conjunction with significant clinical signs and symptoms. The pathologic changes, observed 4-54 months after implant surgery, included a destructive foreign-body-type granuloma and avascular necrosis of the mandibular condyle and condylar neck. Our findings suggest that MR is useful in the detection and evaluation of destructive complications that may accompany failed Proplast-Teflon implants in the TMJ. MR is superior to conventional radiography and tomography in detecting soft-tissue lesions and avascular necrosis of bone. Tomography more accurately delineates soft-tissue calcifications and cortical margins of osseous structures.

The diagnosis of temporomandibular joint disease: two-compartment arthrography and MR.

The reliability and accuracy of two-compartment temporomandibular joint (TMJ) arthrography was compared with MR imaging on the basis of an analysis of surgical findings obtained from joints that had been studied preoperatively with arthrography or MR or, in some cases, both procedures. Seven hundred forty-three consecutive TMJ arthrograms were successfully obtained in a total of 443 patients by using a single 27-gauge needle and a two-compartment technique in each joint. There was a 100% correlation with surgical findings in 218 radiologically abnormal joints operated on within 90 days of arthrography with respect to the presence or degree of meniscus displacement and normal or abnormal disk morphology and function. In 604 patients 1052 TMJs were studied with high-field-strength surface-coil MR. Surgical findings were available for correlation in 170 of the joints studied. Forty-three joints were studied with both two-compartment arthrography and MR. Eight operated joints had been imaged successfully with both two-compartment arthrography and MR. Both methods of evaluation provided highly reliable and accurate information regarding meniscus position and shape. Arthrography was superior to MR in detecting capsular adhesions and the presence or absence of perforation of the disk or meniscus attachments. Simple meniscectomy (with or without insertion of a temporary Silastic TMJ implant) was the most frequently performed surgical procedure in the series, followed by meniscus repositioning procedures. Joint effusions, failed TMJ implants, and avascular necrosis were demonstrated best with MR. Soft-tissue lesions, including intrinsic degeneration of the meniscus, anomalous muscle development, muscle atrophy, tendinitis, and injuries such as contusions and hematomas, were demonstrated only with MR. Partial-flip-angle GRASS (gradient-recalled acquisition in the steady state) techniques permit both fast scanning and study of functional joint dynamic. Joint fluid may appear as high signal intensity on GRASS images because of T2*-weighting. We recommend MR as the procedure of choice for diagnosis of uncomplicated internal derangements of the TMJ. Two-compartment arthrography with videofluoroscopy is an important ancillary procedure that should be performed whenever capsular adhesions or perforations are suspected and not demonstrated with MR and whenever MR is inconclusive.