FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS W. D. MACLENNAN, H.D.D., F.D.S., F.R.C.S.E., F.D.S.R.C.P. & S. Glas. Bangour General Hospital, Broxburn

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1 FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS W. D. MACLENNAN, H.D.D., F.D.S., F.R.C.S.E., F.D.S.R.C.P. & S. Glas. Bangour General Hospital, Broxburn FRACTURES of the mandibular condylar process 'have provided one of the many challenges to the surgeon over the years. The fractures which present vary considerably but are well recognised by those who deal with them. Such controversy as arises is mainly in relationship to treatment. Here we have a field in which the oral surgeon, the plastic surgeon, the general surgeon and the orthopaedic surgeon may all contribute individually or collectively, and this, in part, explains why such widely varying opinions are held on what might at first sight appear to be a relatively simple matter. When the methods of treatment which are employed appear to be uniformly satisfactory, only a critical unbiased appraisal of results over a large series of such cases can possibly indicate preference for one method of treatment as opposed 1o another. In all such studies time plays a fundamental role and the importance of this point cannot be overemphasised. Immediate good post-treatment results are not necessarily maintained. The object of this paper is not specifically to review the available literature on the subject for, indeed, this has been most admirably done in the past (Chalmers, J. Lyons Club, 1947; MacLennan, I952; Blevin & Gores, 196I), but rather to submit the personal views of one who has shown particular interest in the subject-matter for some 25 years. As approximately onequarter of all the facial fractures treated have involved the condylar process, these comments refer to a minimum of I25O mandibular condylar fractures personally dealt with (MacLennan, 1964). Many aspects of the subject have to be considered including the basic development, anatomy and function of the mandible and of the temporomandibular joint; the diagnostic features of fractures involving the condylar process; the methods of treatment employed; the influence of age on prognosis and the long-term results following varying methods of treatment. Without elaborating unduly, the anatomy and function of the temporomandibular joint should be understood. Indeed, it is strange that this knowledge has been relatively inaccurate until recemly. The detailed information available has been gleaned over many years, however, and it is to such as Brash, Last, Sicher, Sarnat and Schour, Rees and Blackwood that we are indebted for our present knowledge. In more recent years, too, experimental workers have added much with original animal experimental investigations and to some of this reference will be made in the course of this paper. It is proposed to discuss only those features which appear to be of significance to the subject-matter under discussion. The condylar cartilage develops about the 4 to 5 mm. Crown-Rump stage and the upper and lower joint cavities first appear in the 5 to 60 mm. Crown-Rump foetus. Vascular canals develop in the cartilage of the 13o mm. Crown-Rump foetus and persist within the growing condylar cartilage until the third year of life (Blackwood, 1961 ). 31

2 32 BRITISH JOURNAL OF ORAL SURGERY It is now generally accepted that the germinal layer, which is situated immediately adjacent to the articular cartilage of the condylar process, is the formative layer in so far as the development from the secondary centre of ossification in the condylar head is concerned (Figs. I, 2 and 3). The previous concept of a carrotshaped growth centre of highly vascular tissue extending down into the condylar neck has largely been dismissed. The potential of the germinal layer to produce a growth response decreases with age but certainly extends well into adult life (Fig. 4). There are basically two causes of condylar fractures--direct violence and indirect violence. The former invariably leads to a unilateral fracture while the latter is usually associated with fractures elsewhere in the mandible, the most common being as follows: (a) Fracture of the body of the mandible anterior to the mental foramen on one side with a fracture of the condylar process on the contralateral side. (b) Midline fracture of the body of the mandible with bilateral fractures of the condylar processes. (c) Bilateral fractures of the body of the mandible, usually posterior to the mental foraminae with a fracture of one condylar process. (d) Grossly-compound comminuted fractures normally associated with extensive soft tissue damage. In those who receive fractures involving the lower jaw there is ample evidence to support the belief that malocclusion of the teeth and/or missing teeth in one or both jaws contributes to the ease of the fracture. This applies in the case of the condylar process. Walker (1942) described two levels of fracture--the high and the low. Radiographically there would in fact appear to be three recognisable types: (i) Intra-capsular. (2) Extra-capsular: (a) Distal sigmosubcondylar. (b) Mesial sigmosubcondylar. These are of some importance when viewed in respect of line of fracture and displacement. MacLennan (1952) suggested that the position of the fractured fragments should be viewed as follows--no displacement, deviation, displacement and dislocation. While HOt as detailed as the subdivisions of Richardson and Cohen (I953), this serves the dual purpose of correlating quite simply the positions of the fractured fragments and the condylar process to the articular fossa. This is important since all condylar fractures involve the joint to a greater or lesser extent. On receipt of trauma there follows a varying degree of limitation of mandibular movement because of (a) muscle spasm; (b) oedema; (c) haematoma; (d) mechanical obstruction, e.g. muscle between the bone ends and malocclusion of the teeth. Muscle spasm accompanies trauma to muscle fibres and is manifest initially by a contractile phase which is later followed by a phase of relaxation. The period between these two is essentially related to the degree of damage and the level of the pain threshold in the individual concerned. Muscle pull is essentially that of the fibres of the lateral pterygoid on the upper fragment. The attachments of these to the neck of the condylar process are of importance, as are their relationship to the capsule. Likewise, the muscle pull on

3 FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS FIG. i 33 FIG. 2 Fig. I. - - M a n d i b u l a r joint of young adult rat (approx. 200 gm.) showing disc, fibrous articular membrane, germinal zone, cellular cartilage and trabeculae of the bony condyle. (69b) x 24 H. and E. By courtesy of R. Sprinz. Fig. 2.--Higher power of (I) showing fibrous articular membrane, the germinal zone and t h e cellular cartilage. (69a) x 96. H. and E. By courtesy ofr. Sprinz. FIG. 3 FiG. 4 Fig. 3.--Mandibular joint of h u m a n foetus (approx. 2o w.i.u.l.) showing large cellular cartilage of condyle, very thin disc, and early formation of the squamous temporal bone. (74) 6. H. and E. By courtesy of R. Sprinz. Fig. 4.--Mandibular condyle of h u m a n adult (male, 42 years) showing dense bone with few vascular spaces, a cartilage layer, a narrow germinal zone and the wide fibrous articular membrane. 16 H. and E. By courtesy ofr. Sprinz.

4 34 BRITISH JOURNAL OF ORAL SURGERY the major lower fragment should not be disregarded, and other muscles of mastication are responsible for this effect. As a high proportion of condylar fractures are extracapsular, the risk of serious complications involving the joint is not so great. Oedcma is present in every condylar fracture and is largely responsible for the limitation of movement which accompanies such fractures. The oedema fluid has its limiting function enhanced by haematoma formation and it is these two entities together with muscle spasm and pull which predispose to the deviation of the mandible as a whole towards the injured side on opening the mouth. Deviation should not be viewed as grossly pathognomonic, for trauma even in the absence of fracture will produce this sign. It is preferable to view this limitation of movement as Nature's way of putting the injured parts at rest, for, indeed, it is easier to open the mouth with minimal discomfort in such circumstances utilizing the hinge component of the temporomandibular joint above and not the sliding mechanism. Should the deviation of the lower jaw persist once the treatment has been completed, it will be necessary to institute measures for its correction. Controlled opening and closing and protrusive and lateral movements of the lower jaw in front of a mirror, aided when necessary by contralateral manual pressure, will normally suffice to rehabilitate the patient. Relaxation of the shoulder girdle is very helpful as a preliminary in aiding the patient to co-operate fully. A simple wedge or top exerciser on the affected side may be of considerable assistance in counteracting any deviation which is present. With intelligent understanding and handling it is seldom necessary to resort to splints with guiding flanges (Gerry, I965). Mechanical obstruction is believed to be caused by muscle fibres becoming interposed between the fractured fragments, but probably this does not happen frequently. Even when it does occur the complication is seldom permanent for the fibres tend to be replaced by fibrous tissue and later may even be replaced by bone. In the grossly comminuted fracture, however, the displacement of individual fragments may interfere with mandibular movement and more especially in those cases of fracture dislocation. In such circumstances the condylar head is disrupted from the articular fossa and may even tear through the capsule. If the interference with function persists and is accompanied, as it so often is, by persistent pain then a condylectomy may be indicated. The general medical condition of the suspected fracture patient is always accorded priority in treatment, and this precept should never be disregarded. No matter how severe the local facial injuries may appear to be, it is always necessary to consider the 4 C's in the following order: I. Control of respiration. 2. Control of haemorrhage. 3. Control of shock. 4. Control of fractured fragments. The diagnosis of condylar fractures is determined after the careful correlation of findings based on clinical history, visual findings, manual examination and the correct interpretation of radiographs. A history of trauma should be followed by details of the force and direction of the blow, the causative agent, and the exact site of the blow. Visually one should note local swelling and bruising. When the patient is asked to open the mouth look for evidence of pain on movement, limitation and

5 FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS 35 possible deviation of the lower jaw towards the injured side. Note the state of the occlusion of the teeth. Manually a series of manoeuvres can be carried out which support the clinical diagnosis of fracture, and which singly or collectively may be well-nigh diagnostic in themselves. Local palpation elicits pain--as will pressure from the contralateral side of the mandible, counter pressure on the lower incisor teeth while the mouth is closing or any attempt at opening while counterpressure is applied on the point of the chin. If the patient is asked to relax so that the normal free-way space relationship is established and the teeth are then brought together by smartly bringing the chin up with the finger and thumb there is instant pain at the fracture site. Radiographic evidence of condylar fractures is undoubtedly confirmatory in most cases. The major problem is to produce uniformly comparable films, especially in the case of young children and in those with extensive injuries elsewhere. Unfortunately it is in such cases that accurate films are of most value. So often in hospital one is confronted with a vast number of radiographs taken in the casualty department, many of which may be virtually useless. The risks of overexposure to X-rays and the cumulative effects are therefore real and should be respected especially ill the young child. A little extra time spent on positioning will pay handsome dividends. The standard A.P. or P.A. projection together with close focus right and left lateral oblique views of the mandible will suffice in the majority of cases. When more detail is required the modified Towne's view and selective tomographs (laminographs) may be of value. Once the diagnosis has been confirmed the treatment of the patient has to be considered. The principle of treatment of all facial fractures is to reduce and immobilise the fractured fragments as soon as possible in as near an approximation to the anatomical position as is consistent with function. It is this emphasis on 'function' which is important with fractures involving the temporomandibular joint, for unduly prolonged immobilisation creates complications. Again, it would appear that as long as there is contact between the proximal and distal bone fragments in fractures of the mandibular condylar process union will take place with an acceptable functional result. There is one proviso, namely, that the older the patient the less is the degree of adaptational moulding likely to be. Obwegeser (i966), however, has demonstrated remarkable powers of adaptation in his bone grafts in this region which seem to indicate that controlled function at the correct time is what matters. There is a tendency to consider that in fractures of the mandibular condylar process only one fragment requires to be moved to achieve a satisfactory reduction, but this is not so. The treatment of the mandibular condylar fracture has for long proved controversial, there being two opposed schools of thought: those who are conservative (MacGregor & Fordyce, 1957; Blevins & Gores, 1961; Greenfield, 1965) and those who are more direct and feel that the techniques employing open reduction methods offer the best long-term results (Sleeper, 1952; Thoma, 1954; Hendrix, 1959; Van Zile, 1965). Before discussing the relative merits of the methods available it is as well to appreciate several points. The first of these is that the reported results following conservative treatment have been uniformly satisfactory. In this respect, animal experimentation would appear to support the belief that fractures of the condylar process unite and that the moulding of the fragments is sound despite the fact that splinting is not utilised. Lastly, those who employ

6 36 BRITISH JOURNAL OF ORAL SURGERY open reduction methods frequently apply them to extracapsular fractures. Technically the procedure is no different from an open operation at any other site in the mandible, except that access is more difficult. To be fair, the reported cases appear to have a satisfactory outcome, although the numbers operated upon are smaller than those treated by the closed method. The author is of the opinion that there is a place for both the open and closed methods of treatment, provided it is appreciated that the consensus of cases will respond well to the conservative approach. In the vast majority of condylar fractures the wound is a closed one, and if conservative methods of treatment can offer satisfactory functional results with a minimum of complications there would be little justification for surgically exposing the area which has potential hazards. Sprinz has carried out a great deal of valuable work on the temporomandibular joint. In respect of the meniscus, he has shown that it is extremely easy to damage this structure and that arthritic and degenerative changes always accompany such injury. This finding would appear to further substantiate the need for reserve in employing the open reduction technique in other than selected cases. He has further shown in rats that fractures of the condylar process unite well and that the subsequent remoulding and adaptation of the bone ends is entirely satisfactory without splinting of any sort (Figs. 5, 6 and 7). While appreciating the difference between the jaws and dentitions of the rat and the human, these findings have been consistently confirmed and therefore cannot be dismissed. As with all fractures the earlier age groups respond most favourably, and the older age groups less so. This perhaps would tend to support open anatomical reduction as the treatment of choice in older patients, but it has been suggested that provided the vertical height of the bite and occlusion are maintained in such individuals, the end-result as a functional entity is quite acceptable with conservative care alone. In the author's personal experience there has been no greater incidence of arthritis in the long-term follow-up of such cases. It is pertinent to point out that there does appear to be a case for direct transosseous wiring of the condylar neck in the bilateral dislocation type with fracture(s) elsewhere involving the body of the mandible. Here, the aim is to aid restoration of the vertical height of the bite and reduce posterior or molar gagging with its associated anterior open bite deformity. When trauma injures the joint unduly, i.e. intracapsular haematoma, torn capsule, etc., prolonged immobilisation is contra-indicated. Possible trauma to the interarticular disc with subsequent late arthritic changes in the joint should always be borne in mind when selecting the open technique as the method of election for treatment. There are a number of factors which will influence the ultimate choice of the method of treatment: (a) The nature of the fracture--simple or compound. (b) The degree of malalignment of the fractured fragments. (c) The actual site of the fracture. (d) The presence of a good dentition or not. (e) The general state of the patient. (f) The nature and extent of other injuries involving the face and elsewhere. This paper deals specificially with the treatment of the fractured condylar process which should be designed to provide and maintain normal occlusion and masticatory efficiency.

7 FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS 37 The illustrations shown previously would appear to suggest that any specific methods employed in the course of treatment would be required to (a) improve on Nature; (b) speed the progress of what Nature will accomplish; (c) deal with cases in which Nature alone would not produce a satisfactory result. Fro. 5 days after subcondylar fracture showing cartilage zones and new bone zone around fracture sites. Also showing additional fracture of ramus. (COC IO4, 45) 3- PAS. By courtesy of R. Sprinz. Fig. 6.--Higher power view of additional fracture in Figure 5, showing distribution of endochondralossification and fibrous tissue stroma between bone fragments. (COC lo4, 45) 28. PAS. By courtesy of R. Sprinz. Fig. 7--Mandibular joint and ramus of mandible of young adult rat eight weeks after subcondylar fracture, showing condylar fragment and ramus of mandible united by fairly dense bone of repair. COC 43/66 x 5"1. H. and E. By courtesy of R. Sprinz. FIc. 7 There is every justification for treating the vast majority of fractures of the mandibular condylar process by conservative means. Where there are a sufficient number of teeth, these should be maintained in occlusion for a period of IO to 12

8 38 BRITISH JOURNAL OF ORAL SURGERY days by any means at the discretion of the operator. Should a bandage be used for this purpose it should be applied from the injured side and should preferably be of the two-way stretch type. The edentulous patient should be treated in a similar manner, the dentures themselves being lined with black gutta-percha or a similar material to avoid pressure ulcers and in order to take up the normal freeway space. In edentulous cases where no dentures are available, Gunning type splints should be made with the bite slightly open. These are then lined with gutta-percha as before and inserted. A supporting bandage is applied once more, but in this case a firm cr~pe bandage is preferable. When there are a number of teeth missing from the dentition, these should be replaced with a bite-block type of prosthesis prior to the application of intermaxillary wires or a bandage. When there are one or more fractures in the body of the mandible as well as a fracture of the condylar process, the splinting of the fracture(s) in the body of the mandible should allow removal of intermaxillary fixation after Io to I2 days. Finally there is the special problem of the fractured condylar process in the young child (Rakower et al., r96i; MacLennan & Simpson, I965). Clinical evidence supports the belief that over the age of 4 years there is less danger of impairment of growth from damage to the condylar growth centre. Again it is the high intracapsular fracture which is most likely to lead to damage. Especially is this so in the fracture dislocation cases where there is a very real risk of damage to the articular cartilage and the underlying germinal cell layer which has been alluded to previously. Irrespective of the damage, these cases should be treated initially in a conservative manner, every effort being made to rest the lower jaw for Io to I2 days. For this purpose an elastic bandage is normally employed as before, although in some cases the Manton type bandage may prove more satisfactory. With the bilateral fractured condyle case a simple overlay splint held in situ with circumferential wires and with slight elastic traction to a Plaster of Paris headcap functions admirably and has the twofold action of slightly opening the bite and allowing the lower jaw to be held upwards and forwards to counteract the downward and inward pull of the depressor muscles. SUMMARY Fractures of the mandibular condylar process have been discussed, particularly in respect of diagnosis and of treatment. Reference has been made to the special problems in the young child. It would appear that conservative treatment will produce satisfactory functional results in the vast majority of cases. The prognosis is best in the fractures without displacement and those with deviation and with displacement when there is still some bony contact no matter how minimal. Again, the younger the patient the more satisfactory the prognosis except in the intracapsular fracture dislocation when damage to the articular surface of the condylar head may produce later secondary deformities. There is a place for open reduction in the grossly displaced extracapsular fractured condyle in the older patient, and also to maintain the vertical height of the bite in selected cases of fracture dislocation, particularly the bilateral condylar fracture dislocation. In conservatively treated cases of fracture dislocation with subsequent limitation of movement and persistent pain open reduction or condylectomy can be considered.

9 FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS 39 ACKNOWLEDGMENTS I wish to express my sincere thanks to Dr. R. Sprinz, Ph.D., B.D.S., F.D.S.Eng., Senior Lecturer in Dental Anatomy, University of Edinburgh, Scotland, for all the illustrations. REFERENCES BLACKWOOD, H. J. J. (1961). Symposium in Royal College of Surgeons, England. BLEVINS, C. & GORES, R. J. (1961). ft. oral Surg. 19, 392. BRASH, J. C. (1924). The Growth of the Jaws, Normal and Abnormal, in Health and Disease. Dental Board of the United Kingdom. ' CHALMERS J. LYONS CLUB (1947). J. oral Surg. 5, 45- GERRY, R. G. (1965). Brit. ft. oral Surg. 3, 114. GREENFIELD, E. M. et al. (I965). Oral Surg. 19, 295. HENDRIX, J. H. (I959). Dental Abstr. 4, 12. LAST, R. J. (1954). Proc. R. Soc. Med. 47, 571. MACGREGOR, A. B. & FORDYCE, G. L. (1957). Brit. dent. J. lo2, 351. MACLENNAN, W. D. (I952). Brit. J. plast. Surg. 5, 122. MACLENNAN, W. D. (1964). J. Roy. Coll. Surg. Edinb. 9, 194. MACLENNAN, W. D. & SIMPSON, W. (1965). Brit. J. plast. Surg. 18, 423. OBWEGESER, H. (1966). Personal Communication. RAKOWER, W. et al. (1961). J. oral Surg. I9, 517. REES, L. A. (1954)- Brit. dent. ft. 96, 125. RICHARDSON, F. H. & COHEN, B. M. (1953). Oral Surg. 6, SARNAT, B. G. (1951). The TemporomandibularJoint. American Lecture Series, Charles C. Thomas, Publishers. SICHER, H. (1948). J.A.D.A. 36, 131. SLEEPER, E. L. (1952). Oral Surg. 5, 4. SPRINZ, R. (1966). Personal communication. THOMA, K. H. (1954)- ft. oral Surg. 12, 112. VAN ZILE, W. N. (1964). J. oral Surg. 22, 461. WALKER, D. G. (1942). Brit. dent. J. 23, 265.