Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-11-28
2003-05-06
Peffley, Michael (Department: 3739)
Surgery
Instruments
Orthopedic instrumentation
C606S208000, C600S239000, C433S140000
Reexamination Certificate
active
06558392
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to mechanical devices for manipulating temporomandibular joints and, more particularly, to devices for reducing or repairing dysfunctional disturbances of the masticatory system. Specifically, this invention relates to a device and method for reestablishing a normal or improved condyle-disc relationship in patients with a dislocated disc. The invention also includes a device and method for distracting the temporomandibular joint in patients suffering from intra-articular adhesions.
BACKGROUND OF THE INVENTION
The temporomandibular joint is a compound multiaxial joint constructed to permit different types of movement (hinge and glide articulation) of the mandible and different degrees of mouth opening. This is made possible by the presence of an articular disc (or meniscus) interposed between the condyle of the mandible and the glenoid (or mandibular) fossa of the temporal bone. The articular disc divides the joint into an upper (glenoid fossa-disc) and a lower (condyle-disc) compartment. In the normal relation, the condyle sits in the articular fossa with its anterior-superior surface closely approximating the posterior-inferior surface of the articular eminence of the temporal bone. A thin portion of the disc rests between the two surfaces, and a thickened portion of the disc rests at the superior angle of the condyle.
Normally, when the jaws are closed, the condyle contacts the disc and the disc contacts the glenoid fossa. If contact is maintained between the upper and lower teeth while gliding movements are performed, this contact relationship should be maintained. During opening movements, a smooth gliding relationship between the upper and lower compartments of the joint should also be maintained. The first phase in mouth opening is a simple hinge action, which involves only the lower (condyle-disc) compartment of the joint. Specifically, it consists of the condyle head rotating around a point on the under surface of the disc, while the body of the mandible drops almost passively downward and backward.
The second phase in mouth opening involves the lower and upper compartments of the joint and consists of a gliding of the condyle and disc forward and downward along the articular eminence. This occurs alone during protrusion and lateral movements of the mandible and in combination with the hinge action during the wider opening of the mouth. A wide opening of the mouth would be impossible with a simple hinge movement since the posterior surface of the ramus would compress the soft tissue between the mandible and the mastoid process. The gliding action brings the ramus forward and also downward so that the hinge action can continue.
Several types of temporomandibular joint dysfunctions can reduce or prevent a wide opening of the mouth. One common joint dysfunction is known as an anteriorly dislocated disc—also known as a posterior condylar displacement. In the temporomandibular joint, the space posterior to the condyle is filled with fibrous tissue that is compressible. The posterior attachment of the superior head of the external pterygoid muscle is posterior on the neck of the condyle. This attachment can stretch or “break down” along with the tight lateral and medial fibers attaching disc and condyle, thus allowing the disc to slide anteriorly on the condyle. If the disc slides anteriorly to the point that the thick portion of the disc rests on the anterior-superior surface of the condyle—instead of its normal resting position on the superior angle of the condyle—this condition is known as a complete anterior dislocation of the disc or a lodged disc.
In patients with a complete anterior dislocation of the disc, the range of condylar translation is limited by the anteriorly dislocated disc on the affected side. This condition often progresses from intermittent locking to acute locking, which usually becomes permanent. A lodged disc forces the condyle to “slip or snap” over the thickened portion of the disc, which may thicken even further as the condition becomes more chronic due to folding of the disc. Thus, the patient experiences a “click” as the teeth are occluded because the condyle is displaced posteriorly but the disc is not, and another “click” occurs as the patient's mouth is opened and the structures regain their normal relations.
A known technique for reducing an anteriorly dislocated disc involves manually manipulating the jaw in an effort to assist the patient to unlock his or her jaw. This is accomplished by an operator or clinician simultaneously pushing down on the lower posterior teeth (or half-arch) while pulling up on the patient's chin. This maneuver is designed to distract the joint. During the first part of the maneuver the mandible must be kept in a retruded (or rearward) position. Importantly, the mandible must never be forcibly pulled forward or forcibly opened unless the joint is also being distracted, as this could damage the joint.
Keeping the mandible in a retruded position, the operator continues to press downward on the posterior teeth (or half-arch) and pull up on the chin. After a few moments, the patient is instructed to move the jaw from side to side, concentrating on moving it toward the side opposite the dislocated disc. While the joint is being distracted and the operator and patient are moving the jaw to the opposite side, the disc will hopefully snap back into place. Although this can sometimes be felt or heard, in some instances there is no noise or other physical evidence that the disc has been repositioned other than the return of full range of lateral movement to the opposite side of the jaw.
After the dislocated joint has been reduced (or the range of movement to the opposite side increased), the patient is instructed to not close the teeth together until a mouth prop can be inserted, which will maintain the mandible in an open position. After keeping the mandible in the open position for about fifteen minutes, the mouth prop is removed and replaced with a repositioning splint (or bite plane). This splint is prepared ahead of time and typically has an extremely large flange extending downward anteriorly to engage the lingual surfaces of the lower cuspids, bicuspids, and incisors so that the patient cannot retrude the mandible when it is near the closed jaw position. The splint will typically maintain the mandible forward of its previous intercuspal position by about 3 mm to 5 mm. The splint remains in place for twenty-four hours a day for at least two weeks, except for brief occasions when the splint is removed for cleaning and brushing of the teeth, during which the mouth prop is used to maintain the jaw in the open position. This period of at least two weeks during which the patient's jaw is maintained in the open position gives the disc a chance to heal.
Another common temporomandibular joint dysfunction that can reduce or prevent a wide opening of the mouth is intra-articular adhesions. Intraarticular adhesions involve an abnormal union of separate tissue surfaces by new fibrous tissue resulting from an inflammatory process. In the temporomandibular joint, the newly formed uniting tissue may form between the anterior-superior surface of the articular fossa and the posterior-inferior surface of the articular eminence of the temporal bone. In patients suffering from such intra-articular adhesions, the temporomandibular joint becomes significantly more difficult to distract due to the increased force that must be applied to overcome the adhesions.
The present invention provides a device that facilitates the operator in distracting the temporomandibular joint and reestablishing the proper condyle-discfossa relationship. The invention also provides a device that is readily adapted to allow increased leverage by the operator when necessary to free the jaw from intraarticular adhesions or other abnormal locking conditions. The device is also advantageous in that permits the operator to more accurately control both the direction and magnitude of forces applied to th
Foley & Lardner
Peffley Michael
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