TMJ Surgery: Open Arthroplasty relief of Lateral Impingement

#1                                                                                                                                                                                                                                              #2

 

 

 

 

 

 

 

 

#5

 

 

 

 

 

 

The above surgical photographs and MRI are of a 27 year old patient with greater than 10 years of progressing pain and mechanical TMJ locking.  Patient related onset of symptoms to teen years.   This is an open arthroplasty procedure, generally performed when significant bone surface abnormalities (Type II impingement)  exist in the fossa (socket) of the TMJ at the base of the skull. This type of disease will not respond to any non surgical dental related treatment or orthotic (splint) therapy. Symptoms generally are associated with advancing  TMJ pain, joint locking in either the closed postion or occasionally stuck open, and significant pain and inability to load the joint to chew food.

#1 is initial exposure of the lateral rim of the glenoid fossa along its anterior-posterior extent from an incision of about 3 cm in length in front of the ear.  Care is taken to approach the joint from behind neural and vascular structures in the area.  Once the joint is exposed, the superior joint compartment (the TMJ has two joint spaces between the fibrous tissue disc/capsule that divides and separates the fossa from the condyle).  In this view, one can see sharp, jagged bone spur or impingement processes which have grown down into the disc/capsule. An incomplete tear of the superior/lateral disc capsule can be seen just below the lateral rim and one of the largest bone spurs (osteophytes).  See previous blog on biomechanics of the TMJ which explains the probable mechanism of development of impingement processes.  (Reference below 1)

#2 Represents initial relief of the impingement.  Bone tissues of the lateral rim of the fossa are relieved/sculpted to begin to match the anterior/posterior and medial/lateral curvature of the glenoid fossa.  This is because the TMJ mechanically must function with compatible curved surfaces which a mechanical engineer would describe as curvilinear general plane motion.

#3 Gross curvature sculpting is continued

#4   Final bone surface sculpting  of the fossa is completed with rotary diamond and hand diamond instruments.  At this point, the disc/capsule is placed such that its inferior concave morphology is congruent with the convex curvature of the mandibular condyle.  Generally, the disc/capsule is extremely loose or flacid due to excessive shear and torque which have hyperextended or torn the lateral capsular attachment to the lateral pole of the condyle.  These attachments are oversewn or reinforced to maintain the adaptation of the disc/capsule during all range of jaw motion.  These motions are at this point to make certain there are no bone impingement interferences impeding rotary or translating TMJ function.

#5.  This is the coronal MRI of this joint.  Note the sharp downward projecting dark pointed projection (Type II impingement) making contact with the condyle and the disc/capsule.  There are different mechanisms in which impingements exert their pathology:  Compression/occlusion impingement when the bone spur digs into the disc/capsule/condyle when the teeth engage during chewing loading of the joint OR   Translation impingement….when the process cuts into the disc/capsule as the entire mechanism condyle/disc/capsule glide forward during mouth opening.

PRACTICAL POINTS OF TMJ SURGICAL ARTHROPLASTY FOR IMPINGEMENT

Arthroscopic surgery of the TMJ was first introduced by Ohnishi in 1980 (2) and expanded and  refined by many of my colleagues at ASTMJS both in the US and internationally. (  references  2-10 ) {See ASTMJS.ORG}  Arthrosocpy is an excellent diagnostic tool and has added much to the understanding of orthopedic pathology  and initial treatment of very early problems of this synovial joint system of the body. In Europe, see F. Monje’s text  published in 2009 with beautiful operative photos and text on the subject.  (  )

Bone impingements, however, can sometimes be so large that they are beyound the ability of microarthroscopes used in TMJ surgery to effectively remove, simply because rotors for bone removal are so small.  Consequently, it is paramount that the operating surgeon look for impingements either with initial arthroscopic exam or pre operative MRI. (only seen on coronal views of the joint).  As in this case, sometimes the magnitude of sculpting is so significant that it can only be performed with open techniques.

Complete post operative recovery includes a patient returning and being able to enjoy a routine diet without pain or dysfunction.  This surgery generally requires adherence to a strict non chewing diet for up to a month, as well as continuous wear of an oral orthotic for a month.  Generally, the joint has not healed sufficiently and repaired disc/capsule tissues developed significant tensile strength to distribute chewing force loads completely for 2-3 months. The orthotic is continued at night indefinitely to protect against unpredictable episodes of night time clenching or tooth grinding which are unavoidable for most of us.  This is analogous to an athlete who has had reconstructive knee surgery wisely wearing a protective knee brace/support while competing after knee reconstructon.

As previously discussed in this web site and other blogs here, significant TMJ problems meriting surgical consideration present in patient populations that are 2-3 decades (20-30 years) younger than patients requiring other orthopedic surgical interventions.  This is because the critical functional component of the TMJ is the disc/capsule and it is composed mostly of fibrous tissue which is vulnerable to rapid and early degeneration (myxoid type) and as a functional orthopedic structure, loses its integrity very early….particularly if developmental impingement are present as well.  Diagnosis and management for those with unremitting pain non responsive to medication and decompression with orthotics is important, particularly to avoid development of chronic pain mechanisms due to irreversable Central Nervous System dysfunctional neural and biochemical pathways.

Examples of irreversibly damaged disc/capsules from patients with even more advanced derangement issues are seen in the introductory sections of this website for both patients and providers.  Biomechanical principles to explain development of TM joint impingement and references (1) are provided elsewhere in the web site and blogs.

References:

1.  Kirk, W. and Kirk, B.:  A biomechanical basis for primary arthroplasty of the temporomandibular joint, OMS Clinics of North America, 18 (2006) 345-368.

2.  Ohnishi, M. Clinical application of arthroscopy in temporomandibular joint diseases.  Bull Tokyo Med Dent Univ, 1980; 27:141.

3. Indresano, T. Surgical arthroscopy as the preferred treatment for internal derangements of the temporomandibular joint. J Oral Max Surg. 2001; 59: 308-12.

4. McCain, JP, Sanders B, Koslin MG, et al. Temporomandibular joint arthroscopy- a 6 year multicenter retrospective study of 4831 joints.  J. Oral Max Surg 1992; 50:926-30.

5.  Israel HA. the use of arthroscopic surgery for treatment of temporomandibular joint disorders. J oral Maxillofac Surg 1994;  52:  289-94.

6.Nitzan DW, Dolwick MF, Heft Mw. Arthroscopic lavage and lysis of the tempormandibular joint: a change in perspective. J Oral Max Surg.1990;  48:  798-801.

7.  Murakami K. “Five Year results of TMJ arthroscopic surgery correlated to stage of internal derangement”.  Lecture, Annual Meeting, ASTMJS , February 28, 1997, Palm Desert, California.

8.  Hall, HD, Indresano AT, Kirk, WS, Dietrich, M. and Gibbs. Prospective multicenter comparison of 4 temporomandibular joint operations.  J Oral Maxillofac Surg 2005; 63:  1174-9.

9.  Moses, JJ et al:  The effect of arthroscopic surgical lysis and lavage of the superior joint space on TMJ disc position and mobility.  J Oral Max. Surg. 1989;  47:  674-8.

10.  Bronstein SL and Merrill RG:  Clinical staging for TMJ internal derangement:  application to arthroscopy.  J. Craniomand Disorders, 1992;  6: 7.

Dr. W. Kirk, Jr.

Charlotte

Tags: Add new tag, jaw joint, orthopedic surgery of jaw, TMJ Impingement, TMJ Surgery