CHAPTER 6 ARTHRODIASTASIS OF TFIE ANKLE JOINT, AN ALTERNATIVE TO FUSION

George R.Wto, DPM Leomard Talarico, DPM

INTRODUCTION It should be noted that adjunctively, arthroscopic lavage cor-rld be performed at the same time as Presently, we know of two major forms of frame application. osteoarthritis, both of which can be severely The primary reason that this particular disabling. In primary osteoafihritis the cause is procedure was chosen is because it has been generally unknown, and in secondary osteoafihdtis reported that when intermittent hydrostatic pressure the cause is generally ffaumatic in origin. Both forms is applied to human osteoarthritic catilage in tissue present with similar clinical symptoms, which culture the result was a significant increase in the include pain, decreased range of motion, and synthesis of proteoglycans. Recall that proteoglycans swelling. Radiologically, there is a decrease in the provide arlicular cafiilage with its compressive joint space, and presence of osteoph),tes and propefiies. Thus, hypothetically, when intermittent subchondral cysts with sclerosis of subchondral intraarticular hydrostatic pressure is applied to bone. Extracel1ularly, afiicular cafiilage has two human articular cartilage, in the absence of mechan- principle components. Collagen that gives it shape ical stress, the result could be a reparative activity by and tensile strength and proteoglycans, that give the chondroq,tes in the osteoafihritic cartilage. A arlicular cafiilage its compressive propefties. In secondary reason for making this choice is that this osteoafihritis there is an imbalance between the procedure is not joint destructive. synthesis and the release of these two components. Under general anesthesia, one of two types of This leads to both a disruption of the collagen external fkation was applied. These included either network and a loss of proteoglycans. These the Ilizarov ring apparatus or a mono lateral flxator. biochemical changes that occur appear to have no Application of the llizarov apparatus involved tw-o diagnostic clinical correlation, especially in the early leg rings applied to the tibia and attached with stages of the disease process. screw-threaded rods. A footplate was then applied Treatment of osteoarthritis has included with two wires in the calcaneus and two wires antiinflammatory medications and exercise. Also, through the metatarsals. The footplate was then arthroscopic joint lavage coupled with subchondral fked to the 1eg rings with two hinged rods and one bone drilling has been used. None of these screw-threaded rod posteriorly to initially prevent modalities have proven to provide significant ankle motion for the first two weeks postoperatively. improvement in symptoms, 1et alone a cure. The The mono Tateral fixator involved placement of half ultimate end for patients with osteoarthritis is pins into the tibia, talus and calcaneus. Fixation of complete destmction of the articular cafiilage with the ankle joint was also maintained for the first two resultant need for afihrodesis or arthroplasty of the weeks postoperatively. affected joint. Distraction was achieved on the operating table and was then carried out until approximately 5mm THE PROCEDURE of joint space was achieved. The patients were encouraged to ambulate to tolerance on the first Recently, five patients who were candidates for postoperative day. Load bearing on the distracted afihrodesis of the tibiotalar joint as a result of either joint was essential in order for there to be an primary or secondary arthritis were offered another increase in the intraarticular hydrostatic pressure. treatment option, diastasis of the tibiotalar ioint After two weeks, ankle joint motion was allowed using external fixation. The goal of the surgery was with the use of hinges. Exercises for range of motion to eliminate mechanical stress on the ankle joint by were performed and ambulation was encouraged. preventing contact between the tibia and the talus. During the treatment period with either fixator there CHAPTER 5 3t

instances the author Llses a Jones compression The patient is then re-evaluated two weeks later, dressing. This type of cast is usecl during rhe initial at which time the distal and proximal pins are postoperative phase as it provides a measure of removed from the erlernal fkator. Weightbearing protection for the external frame. Although this is continues for an additional two weeks with only two not a necessity, it does generally provide a certain of the remaining pins in p1ace. At that time, the level of comfofi and security for the patient tintil remaining pins and exlernal fxator are removed. This they can become adfusted to the presence of the allows the osseous tissues to adapt to weight-bearing frame. The cast is usually discontinued within the stress over time, reducing the likelihood of plastic first week or so after the surgery. deformation of the more immature bone substance. In some patients the distraction process will The greatest drawback to this type of proce- resr-r1t in deviation of the toe due to the tension that dure is the lengthy period of nonweightbearing that is placecl on the flexor or extensor tendons. A may be required in some patients. On average, it number of authors have described inserting a takes abor-rt three months before patients are ready Kirschner-wire into the associated digit, and at times to begin ful1 weight-bearing without the external across the metatarsophalangeal joint as it is believed fixator when a lesser metatarsal has been addressed. by some that the use of the wire will tend tcr How-ever, patients undergoing surgery on the first mediate this effect. The author has not found that this metatarsal generally require a much more lengthy is a problem, and a pin is not used routinely in the interval of nonweightbearing, sometimes extending associated toe. However, there have been some up to sk months. patients where the toe required some additional splintage with tape during the lengthening process to Complications ovefcome problem. this type of Potential complications with this approach are gen- erally minor and usually will consist of some type of Postoperative Care digital deformity due to the altered tension on the As noted above, the patient is usually placed into a tendons. Mild cases of dorsal nelve entrapment have Jones compression cast initially. The patient is main- also been encountered, but these have responded tained nonweightbearing until it is deemed that well to locai injections of corticosteroid. sufficient lengthening and healing have occurred. At Fufihermore, in some patients the degree of scarring two weeks after surgery the patient will begin the in the skin can be objectionable. This is due to the distraction process, turning the apparatLls one- fact that linear tension is being applied to the scar quafter tllrn every six hours. Racliographs are then during the initial healing interva1. Therefore, the made periodically to assess the amount of lengthen- author attempts to warn all patients prior to under- ing which has been achieved, and once this is felt to going the procedure that this may be a factor after be sufficient, the patient is instructed to discontinue surgery. This may be particularly important when the distraction process. Should the metatarsal be patients are undergoing the procedure primarily for ovedengthenecl, the reverse process can be cosmetic reasons. However, the scar can ceflainly employed, that being shofiening of the metatarsal be excised and primarily closed at a later time, until a sufficient length has been achieved. rendering a more appealing scar for the foot. Afterwards, the patient is evaluated periodically with radiographs to cletermine when there has been Conclusion sufficient healing for initial weightbearing. Once this Overali callous distraction is a viable alternative in a interval has been achieved. the author will allow the select patient group to address shofiening of a patient to begin initial weightbearing with rhe pins metatarsal. However, the author's preference in most and frame in place. It is felt that this provides some situations is to employ a sagittal Z osteotomy, if measure protection against of excessive weight- feasible. This approach is simple, effective, and bearing forces on the newly lengthened area of involves less recovery time than if callous distraction bone. The author has seen patients some where or bone grafting is required. Nonetheless, callous sagittal plane deformity has developed in the distraction is effective, and may be preferable in metatarsal weightbezrring once was instituted. In most situations where previous infection has been those circumstances, it was usually due to the fact a problem. that the frame was removed prior to the institution of weightbearing. CHAPTER 6 33 was radiographic evidence of increased joint space been suggested that by distraction of the joint there with the patient fuli weight bearing. The assumption is a subsequent increase in the circulation of was made that the weight bearing surfaces of the synovial fluid that provides nutrition to the afiicular tibia and the talus did not come into contact during cartilage. For whatever reason, diastasis of the ankle the time of distraction. Total time of distraction was joint, with elimination of mechanical stress, leads between five and sk weeks. The frame was then to improvement in the articular cafiilage and a removed and the patients continued with physical reduction of the symptoms of osteoarthritis. therapy and ambulation to tolerance. The purpose of performing diastasis of the The resultant effect of diastasis of the tibiotalar tibiotalar joint in patients with severe osteoarthritis joint is an elimination of normal mechanical stress was to delay the need for arthrodesis. Thus far, five placed on the articular cartilage due to the absence patients have been treated in this manner. Clinically of contact between the joint surfaces and aL all patients continlle to experience a recluction in intermittent increase in intraarticular hydrostatic pain, an increase in joint range of motion, and pressure. As previously mentioned, in tissue culture radiographic appearance of joint space. \[ith this ,cartilage displays reparative activity when placed in positive clinical evidence it appears that ankle ioint these conditions. The primary reparative activity diastasis, with either the Ilizarov apparatus or a noted was that of increased proteoglycan production monolateral fixator, may deiay the need for by more than 50%. It can be speculated that this arthroclesis in patients with primary or secondary increase in synthesis of proteoglycans may be the osteoarthritis. reason for the increase in joint space. It has also

Figure 1. Preoperative AP radiograph of the Figure 2 Post distraction AP racliograph srith ankle lrame CHAPTER 6

Figllre .1. Postoperatile latcral vie\\. of extcrnal fkator

Fignle J. PostopcrlLtive clinical At, r-ies of crter. nal flrator.

Figue 6. Postoperative latelal vics- of ankle at 1 ve.Lr

Figure 5. Postoperati\.e A1) r':rcliograph of ..rnkle :rt 1 ycar'.