Current Topic Review Chronic Lateral Ankle Instability J. Wesley Peters, M.D., F.R.C.S.C.: Saul G. Trevino, M.D.,t and Per A. Renstrom, M.D., Ph.D.+ Burlington, Vermont

ABSTRACT Chronic lateral ankle instability may be present in as many as 10% to 30% of people suffering from acute lateral ankle ligament injuries. Ankle instability has been referred to as either functional instability or mechanical instability. Management options consist of either nonoperative or operative treatment, with the majority of the literature emphasizing operative management for chronic instability. Long-term studies assessing the different types of available operative repairs have now been published. This review article discusses chronic lateral ankle ligament instability from a functional, anatomical point of view. The indications for treatment, nonoperative and operative treatment, as well as the biomechanical information available regarding these methods of treatment are considered. The major emphasis of this review is discussion and analysis of the many different surgical treatment options. Following this review, we presently recommend anatomical repair to the bone of both the anterior talofibular ligament and the calcaneofibular ligament, together with imbrication of the ligaments. In patients with hypermobility, long-standing instability, or arthritis, reconstruction using the Chrisman-Snook technique is recommended.

Most ankle sprains occur in the 15- to 35-year-old age group.6 Both athletics and injury in activities of daily living can be implicated as common causes of ankle ligament sprain. 21,65 Ankle sprains account for 25% to 50% of injuries in sports such as basketball, volleyball, soccer, and football and other sports that include running and jumping activities. 52 Treatment of these acute injuries has been the subject of recent review papers. 6,38 Despite adequate treatment of acute ankle ligament injuries, there is a significant number of sequelae. It is estimated that approximately 10% to 30% of patients with lateral ankle ligament injuries may suffer from chronic symptorns.s"" Common complaints include pain, the feeling of giving way, frank instability, and recurrent swelling. 1,5,3o The severity of the initial injury does not correlate with the severity of the residual symptoms." Ankle instability appears to account for the majority of these symptoms. About 10% to 20% of patients with acute ligament rupture may require surgery for chronic instability." Classically, the lateral ligament complex of the ankle is described as consisting of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The ATFL is a thickening in the anterolateral joint capsule running approximately parallel to the foot in the neutral position. The ATFL becomes taut and parallel to the tibia when the foot is plantarflexed. As plantarflexion increases, strain in the ATFL increases." This ligament is the most commonly injured ligament of the lateral complex, since most of these injuries occur in plantarflexlon." The CFL is extra-articular, but intimately associated with the overlying peroneal tendon sheath. The CFL is rarely injured alone, but is associated with ATFL tears in more severe injuries. The CFL acts as a collateral ligament with the foot in dorsiflexion, where it is perpendicular to the joint and under the most tension. These two ligaments act synergistically to control lateral stability

INTRODUCTION

Injury to the lateral ankle ligaments is a common, everyday injury mainly seen and treated in emergency rooms, sports medicine clinics, and orthopaedic offices. It has been estimated that there is about one inversion injury of the ankle per 10,000 persons per day.?,54,63 One third of West Point cadets were found to have sustained ankle sprains within a 4-year time period." From the Department of Orthopaedic Surgery, University of Vermont, Burlington, Vermont 05401. • Fellow, Foot and Ankle Service, University of Vermont. To whom requests for reprints should be addressed at Department of Orthopaedic Surgery, University of Vermont, 1 So. Prospect St., Burlington, Vermont 05401. t Associate Professor, University of Vermont. :/: Professor, University of Vermont.

182

Foot & Ankle/Vol. 12, No. 3/December 1991

in the unloaded ankle. The PTFL is the strongest ligament of the lateral ligament complex and is rarely injured, except in severe ankle traurna.v" ANKLE INSTABILITY

Two types of instability, mechanical and functional, have been described. Freeman et al.20 introduced the term functional instability to describe the patient's subjective complaint of giving way in the ankle joint. This feeling often occurs during physical activity, but it may occur during activities of daily living, such as walking on uneven ground or turning around corners. Tropp" defined functional instability as motion beyond voluntary control but not necessarily exceeding the physiologic range of motion. The possible causes of functional instability include a proprioceptive disorder,"? muscle weakness," and subtalar tnstability." Mechanical instability is motion beyond the physiologic range of motion. Lateral ligament mechanical instability is demonstrated clinically by performing the anterior drawer and talar tilt tests. A positive anterior drawer test in the neutral and plantarflexed positions implies incompetence of the ATFL, the primary restraint to anterior talar translation in the unloaded joint. A positive talar tilt test performed in the neutral or dorsiflexed positions implies incompetence of the CFL, the primary restraint to inversion in this position. In plantarflexion, the talar tilt test examines the integrity of the ATFL. Stress radiographic evaluation of the ankle while performing anterior drawer or talar tilt tests may be used to confirm the clinical instability. The technique and indications for stress radiographs as well as the determination of normal and abnormal values remain controversial. An excellent discussion on the clinical and radiographic diagnosis of mechanical instability can be found in a recent review.6 There is no correlation between mechanical and functional instability of the ankle in individual patients.":" Tropp" demonstrated that more than half of functionally unstable ankles were mechanically stable. He also demonstrated that the ability to maintain postural equilibrium was reduced among a group of soccer players with functional instability, but not affected by mechanical instability. He proposed that ankle joint injury produces one or more of several sequelae that include mechanical instability, muscle atrophy, and functional instability. The degree of disability correlates best with the number of these factors present. Mechanical and functional instability may be parallel phenomenon, but they are not correlated.

CHRONIC LATERAL ANKLE INSTABILITY

183

DIAGNOSIS OF CHRONIC INSTABILITY

The diagnosis of chronic lateral ankle instability relies on a history of injury and functional instability. Complaints of pain, swelling, a feeling of giving way, or actual reinjury predominate. These may occur during sports, walking on uneven ground, or activities of daily living. The history is confirmed by clinical and radiographic stress tests. A deficiency in the strength of the peroneal muscles is suggestive of the diagnosis. Positive anterior drawer and talar tilt tests establish the diagnosis of mechanical instability. Confirmation of mechanical instability may be obtained by stress radiographs taken in a standardized fashion. Using a stress device, Karlsson et al." found that an anterior drawer of 10 mm and a talar tilt of go or greater reliably indicated mechanical ankle instability." Differential diagnoses of chronic lateral instability must be kept in mind. Peroneus tendon subluxation or tear, anterior tibiofibular ligament injury, osteochondritis dissecans, and avulsion fractures must be considered." These conditions may be isolated or associated with the instability. Sinus tarsi syndrome, subtalar instability, and transverse talar instability may give symptoms of instability similar to ankle instability. Cavovarus deformity of the foot may be a predisposing feature." TREATMENT OF CHRONIC INSTABILITY

The emphasis of most reports has been on the operative treatment of ankle instability. Some authors do report that conservative treatment was undertaken prior to surgery. Unfortunately, there is a paucity of data available regarding the specific type and outcome of nonoperative treatment.

NONOPERATIVE TREATMENT

The common nonoperative treatments consist of physical therapy modalities and taping or bracing. These methods of treatment may be applied to any patient with symptoms of instability. The treatment of functional instability should emphasize muscle strengthening and tilt board or ankle disk training.3 ,4,20,53 ,76 Nonoperative treatment consisting of peroneal muscle strengthening and ankle disk training has been shown to give objective and SUbjective improvement in soccer players with functional instability." The same author concluded that 10 weeks of treatment resulted in maximum benefit. The results of conservative treatment of combined functional and mechanical instability have not been reported in the literature, presumably because most of these patients are operated upon. Theoretically, since not all mechanically unstable

184

PETERS ET AL.

ankles are functionally unstable," conservative treatment may relieve symptoms by improving strength and muscle reaction time without affecting the mechanical component. This method of treatment should be tried for all patients with chronically unstable ankles and is definitely indicated for less active, low demand, and minimally symptomatic patients. Ankle taping and bracing have been shown to be of prophylactic value in preventing ankle injuries. 16,22 Taping is effective in preventing the extremes of ankle motion, but loses 40% of its effectiveness after 10 min.25,47,58 Laced braces worn in combination with lowtopped shoes were shown to be more effective than taping in a group of collegiate football players." Subjective improvement has been noted in athletes wearing braces for functional instability. Ankle braces may reduce the incidence of recurrent sprains, thus reducing the symptoms of instability. There are no randomized studies that report on the success rate of treating individuals with chronic unstable ankles by these means. OPERATIVE TREATMENT

The majority of the literature available on chronic ankle instability consists of reports on operative treatment. More than 50 procedures or modifications have been descrlbed." Cynics may, therefore, be led to conclude that the type of procedure is irrelevant and that results must be universally good or poor. The remainder of this review will address the more popular and adequately reported of these procedures. Chronic ankle instability as demonstrated by pain, recurrent giving way, and positive stress tests is a major indication for surgical treatment. Failure of nonoperative management of ankle instability is, therefore, an indication to proceed to surgery. The combination of mechanical and functional instability is the most commonly reported indication for surgery. The importance of radiographic stress tests to demonstrate instability preoperatively is controversial. The lack of clear definitions in regard to radiographic instability and technique has prompted many to rely on clinical judgment alone. Others continue to use radiographic criteria and attempt to refine these criteria in the process. 25,39 Although most acute ankle injuries occur in young individuals, chronic instability may become symptomatic at any time. Age itself appears to have little bearing on surgery in that reports include patients of all ages, although young or middle-aged persons predominate. History of Operative Treatment

Nilsonne55 reported first on reconstruction of lateral ankle ligaments for chronic lateral ankle instability. He

Foot & Ankle/Vol. 12, No. 3/December 1991

transposed the tendon of the peroneus brevis muscle into a subperiosteal groove behind the lateral malleolus, successfully reconstructing the lateral ankle ligaments. Elrnslie'" published a report on the reconstruction of both the ATFL and the CFL using a fascia latae graft. Watson-Jones 80 reported on a procedure in which the peroneus brevis tendon was routed through the fibula into tunnels in the talus to reconstruct the lateral ankle ligaments. In 1953, Evans!" reported on a simpler procedure in which the peroneus brevis tendon was simply tenodesed to the fibula. Based on these classical studies, numerous modifications have been published. The peroneus brevis tendon, either a full tendon or half the tendon, has been the commonest graft chosen for these reconstructions. The peroneus longus tendon,82 the medial one third of the Achilles tendon,72,73 and the plantaris tendon have been used as a graft for the ligament as well as the fascia latae. Haig29 used a slightly different technique and transposed the anteroinferior tibiofibular ligament attached to a tibial bone block to replace the ATFL. The supplementation of grafts using osteoperiosteal flaps has been described by Lee50 and Zwipp and Tscherne." More recently, bovine couaqen" and carbon fibers 10,37 have been suggested as alternative graft materials. In direct contrast to the use of imported tissues, Brostrom," after an extensive prospective study of a group of patients with ankle ligament injuries, concluded that it was possible to repair chronic ankle ligament injuries by direct suture, even many years after the initial injury. Subsequent to this report of finding the ligament ends visible and intact and being able to approximate them long after injury, other authors have also attempted more anatomic reconstructions. Not all have been able to find the ligament ends, but have found, rather, that the ligaments have healed elongated, encased in fibrous scar tissue. It has, however, been possible to either imbricate or shorten the ligaments and reimplant them into bone to achieve a more anatomical reconstruction. 1,27,29,42,83 Classification of Operative Treatment

We feel that examining such a large number of alternative surgical techniques may be facilitated by grouping them into similar categories. Thus, we propose the following classification (Table 1). The surgical procedures should be divided into reconstructions in which another structure or material substitutes for the injured ligament, and repairs in which the injured ligament is repaired secondarily with or without augmentation. Reconstruction may take place with endogenous or exogenous grafts. Ideally, classification of the graft would be according to the specific donor material. Unfortunately, similar graft material has been used in many

Foot & Ankle/Vol. 12, No. 3/December 1991 TABLE 1 Classification of Operative Treatment I. Reconstruction (nonanatomic) A. Endogenous Peroneal tendon

Other

Watson-Jones Evans Chrisman-Snook Plantaris Partial Achilles tendon Free autogenous graft

B. Exogenous Carbon fiber Bovine xenograft II. Repair (anatomic) A. Direct suture B. Imbrication and repair to bone C. Local tissue augmentation

ways. Therefore, it has been necessary to retain the specific names by which the different procedures have become known. Ligament repairs have been classified in keeping more with the fashion in which the technical part of the repair is accomplished. Results of Operative Reconstruction

Elmslie reconstruction. Elmslie17 described four cases of lateral ankle instability in which the lateral ligaments were reconstructed by the use of a free graft of fascia latae. The fascia latae graft was placed through a drill hole in the fibula with one arm of the graft being extended through a drill hole in the talus to replace the ATFL and the other arm of the graft being placed through a drill hole in the calcaneus to replace the CFL. There are no large series or long-term reports on the Elmslie procedure using the fascia latae, since most surgeons prefer not to make a second incision to harvest the fascia latae. However, this particular procedure is historically important, since it attempts to reconstruct both the ATFL and the CFL and forms the basis of the Chrisman and Snook 11.71 modification by using one half of the peroneus brevis tendon to affect a very similar repair. Watson-Jones reconstruction. Watson-Jones 80 described a tenodesis used to correct instability arising from injury of both the ATFL and CFL. The ATFL was accurately reproduced by one limb of the graft, but the so-called CFL reconstruction was actually at right angles to the line of the original ligament.8.11 The original procedure described using the whole of the peroneus brevis tendon detached proximally and woven through a drill hole in the fibula, following which it was passed through a hole in the talus and back to the fibula. Subsequently, many modifications to the original procedure have been proposed, including use of the peroneus longus tendon" and use of the split peroneus brevis tendon. 5.51 Also, the exact routing of the graft

CHRONIC LATERAL ANKLE INSTABILITY

185

and placement of the drill holes have been subject to some variation in several reports. A Watson-Jones repair or its modification has, however, been one of the most popular lateral ligament reconstruction procedures. Numerous reports on its results exist and a significant number of long-term follow-up studies are available for review. Overall, nine clinical series of Watson-Jones and slightly modified reconstructions consisting of a total of 250 ankles have been reported.5.24.3o.32,34.51.78.79,82 The patients were reviewed retrospectively from 1 to 7 years after surgery, except in one series in which the average follow-up was 22 years after surqery." Stability was regained in at least 95% of ankles, with good to excellent outcome in 80% to 85% of the cases. Stress radiographs were used to determine stability in five of these studies.6.3o.32.51.78.82 The most common reason for a good result instead of an excellent one was mild ache after vigorous activity. Sural nerve neuroma was reported in 0% to 10% of cases. The most common reported complication was restricted range of dorsiflexion and inversion in 10% to 30% of cases. Van der Rijt and Evans'" reviewed nine patients an average of 22 years after their Watson-Jones reconstruction. Instability or insecurity was present in 66% of cases, as was a positive anterior drawer on stress radiographs. Several late failures were noted in patients with initially stable reconstructions. Criticisms of this reconstruction include its technical difficulty, as well as problems obtaining a long enough portion of the peroneus brevis tendon. Anterior drawer is well controlled at the price of a high incidence of restricted adduction and internal rotation." The posterior arm of this graft does not duplicate the anatomy of the CFL; therefore, external rotation and subtalar motion are not controlled.F" Kjaersgaard-Anderson et al.43 concluded that these ankles have abnormal kinematics. Evans reconstruction. Evans18 also described a tenodesis procedure of the peroneus brevis tendon to treat chronic lateral instability. The procedure that he described was somewhat simpler than the WatsonJones reconstruction. The Evans procedure consists of a simple transection of the peroneus brevis at the musculotendinous junction, following which the proximal portion of the distal tendon is passed from anterior to posterior through a drill hole in the distal fibula. Evans reattached the tendon to the muscle in a slightly overlapped fashion, whereas others have sutured the tendon to itself at this level and sutured the remaining stump to the peroneus longus as a modification of the original procedure. 28.57 This has also been a popular procedure, and, in particular, its simplicity has made it quite attractive. Several long-term follow-up studies are available for examination.

186

PETERS ET AL.

Eleven clinical series with a total of 360 ankles treated with Evans' tenodesis or slight modifications have been reviewed. Overall, 90% to 100% stability and 80% to 95% good and excellent results have been reported on retrospective review. 18,28,41,44,48,56,57,70,74,77,83 Stress radiographs are reported in eight of these studies for the determination of ankle stability.28,41,44,48,56,57,77,83 The only exception to these results at 2 to 7 years after surgery are reported by Orava et aI.,56 who noted an almost 50% incidence of radiographically proven increased anterior drawer. Complications include up to a 4% incidence of neuroma and a 30% incidence of restricted inversion. Silver and Deutsch'" felt that all of their patients had decreased inversion. Karlsson et at.," in a more detailed 14-year followup, noted that 50% of patients had fair and poor results. Specific complaints were of pain and instability. Of the patients who had returned to sports, 40% ceased to participate due to recurrence of symptoms. A deterioration in stability was noted in 16 of 42 persons. All patients with increased talar tilt after reconstruction did poorly and showed osteophyte formation on x-ray. The Evans procedure reconstructs neither the CFL nor the ATFL, but acts upon the resultant of the twO.41 The talus may still sublux forward when the ankle is plantarftexed." ,74 Despite these criticisms, good clinical results and technical ease have made this a popular procedure. Chrisman-Snook reconstruction. Chrisman and Snook," based on their experimental investigation, felt that reconstruction of both the ATFL and the CFL was important. They subsequently devised a procedure that was very similar to the Elmslie procedure, although the graft material used was a split portion of the peroneus brevis tendon. In 1985, they reported a long-term result of the reconstruction, together with some slight modifications in the technique. The technique, as described in this later publication, involved a long, curved incision over the peroneal tendons, protection of the sural nerve, and then harvesting of the split peroneus brevis tendon, with the tendon left secure at its distal attachment. Half of the peroneus brevis was then used as the graft material, while the rest was left intact. The tendon was left attached distally, brought through a tunnel in the fibula at approximately the level of the tiblotalar joint, and routed anterior to the peroneal tendons through a tunnel placed in the calcaneus. Following this, the graft was brought back to the anterior aspect of the talus. The graft was sutured in place on the anterior aspect of the talus at the insertion of the ATFL and at the entrance and exit of each of the bone tunnels. Four clinical series with a total of 100 ankles were available for review.59,61 ,67,71 Overall, a greater than 95% rat~ of stability was reported, with over 90% of the

Foot & Ankle/Vol. 12, No. 3/December 1991

patients rated as having good or excellent results. In two of these clinical series, stability was determined postoperatively by the use of stress raoioqraphy.":" Patient follow-up was approximately 2 years in each of these studies, although Chrisman and Snook reported an average 10-year follow-up. The complications reported included neuromas in 0% to 16% of operative patients. Restricted inversion was found to some degree in all patients and restricted dorsiflexion in approximately 20% of patients. Snook et at." undertook a thorough review of their reconstruction in patients with an average of 10 years of follow-up. A total of 48 patients were reviewed. They found that 93% of their patients achieved good and excellent results. Good results were due to minor aches on strenuous activities. These authors felt that a loss of 20° or less of inversion was consistent with the surgical procedure performed and they did not report this as a problem. They did feel that two thirds of their patients did achieve normal inversion. The only recurrences over this time period were three cases in which patients sustained significant trauma to the operated ankle. The Chrisman-Snook tenodesis was felt to be an improvement over the other reported tenodeses, since there was less lateral weakness involved by using only half of the peroneus brevis tendon as the graft material.71 Restricted subtalar motion has been a criticism of this procedure. However, advocates describe subtalar restriction as one of the important aspects of this procedure, since subtalar motion is better controlled than in the Evans and Watson-Jones tenodeses. Riegler61 referred to the high incidence of sural nerve injuries, which has also been a criticism of this particular procedure." Colville et al." have also criticized this reconstruction as failing to control internal rotation and anterior drawer. However, it does control talar inversion at the expense of restricting subtalar motion. They have also concluded that this reconstruction is nonisometric in its graft placement. Although the Chrisman-Snook procedure is relatively recent, two modifications have been described. Sammarco and DiRaimond065 described very similar results in 43 patients treated by modification of the ChrismanSnook procedure. They felt that the alignment of the graft was improved by creating an osseous tunnel in the talus, thereby slightly changing the direction of the tunnel within the fibula and placing the graft deep to the peroneal tendons. Leach et al.49 described a modification used on 22 ankles in which the graft was fastened to the calcaneus using a staple rather than through an osseous tunnel. Again, the clinical outcome was very similar to that reported by Chrisman and Snook.

Foot & AnklejVol. 12, No. 3jDecember 1991

Other endogenous reconstructions. Several other studies have reported on modifications of these basic reconstructions, either using other materials or slightly different techniques. None of these modifications have been popularized by multiple clinical studies. Lee50 reported on a modification of the Watson-Jones procedure in which a portion of retinaculum and periosteum from the fibula was turned down as a flap over the reconstruction that had been performed using the peroneus brevis tendon as a graft. In his report of seven patients followed for 5 to 12 years, he reported good results. Unfortunately most of the clinical follow-up was via questionnaire, with no objective data reported. Other reported procedures have been transfer of the anterioinferior tibiofibular ligament together with a bone block from the tibia to the talus 29 and simple shortening of the peroneus brevis tendon." The medial one third of the Achilles tendon has been used as the tissue for reconstruction in an attempt to create a vascularized graft. 72,73 The tendon was left attached to the calcaneus, brought through a hole in the calcaneus, and then woven through the fibula and tibia to recreate the lateral ligaments. This procedure could be staged as a two-part procedure to reconstruct the CFL also. The Achilles graft was detached proximally at a second sitting and reattached to the calcaneus. Theoretically, this was to provide a vascularized tissue that would be stronger and more lasting. The plantaris tendon, either free or attached to the calcaneus, has been used 2 ,68 in a small group of patients to reconstruct the ATFL by attaching it through drill holes in the fibula and talus. Postoperative stress radiographs have demonstrated stability after use of the plantaris tendon as a ligament substitute." Alternative procedures have also described using the peroneus brevis tendon split into aT-shape to reconstruct all parts of the lateral ligament complex" or using it as a free graft fastened to the bones with screws." Unfortunately, these studies suffer from a lack of numbers of patients and objective data. Exogenous reconstructions. Carbon fiber is a material that has attracted interest in the orthopaedic community as a possible ligament substitute. Clinical trials of its use as a lateral ankle ligament substitute have been reported.":" In the larger of the two series, 82% of 40 patients were reported to have had excellent results with minimal cornpucations." However, in the smaller of the two series, it was noted that two of the five grafts required removal due to chronic sinus formation and skin breakdown." Skin breakdown and chronic inflammation were also reported as a problem in four out of 20 ankles in which bovine collagen was used as the graft material." The necessity for use of an exogenous material and the indications for their use remain unclear at this time.

CHRONIC LATERAL ANKLE INSTABILITY

187

Comparative Studies of Reconstructions

When attempting to compare multiple different clinical series of several different operative procedures, it is difficult to draw significant conclusions. The indications for surgery are variable and in many cases not well reported. The procedural techniques are also somewhat different and the methods of evaluation are not only variable, but, in many cases, sketchy and haphazard. In the very few cases in which objective data are reported, such as stress radiographs, the variability in technique again makes comparisons difficult. Better information can be obtained from studies in which one group of authors has evaluated several different repairs performed by their own hands. Younnes et al.81 compared the clinical results of 10 Watson-Jones and 10 Evans reconstructions. The 5year follow-up time would appear to be adequate for comparing the two results initially. On clinical and stress radiographic examinations they felt that the WatsonJones reconstruction better controlled anterior drawer, whereas the Evans procedure better controlled talar tilt in their patients. All of their patients had some degree of limited inversion. The overall patient outcome was reported as 90% good and excellent after the Evans repair and 100% good and excellent after the WatsonJones repair, based on patient satisfaction, physical examination, and radiographic stress tests. St. Pierre et at.64 examined 53 ankle reconstructions using five different techniques. This was a multi-institutional study of patients who had either Evans, Watson-Jones, Chrisman-Snook, Goldner, or Lee reconstructions performed. The clinical evaluation concluded that there was no significant difference in the outcome according to the type of reconstruction performed. The length of follow-up was not reported. Horstman et al.35 were surprised to find a high incidence of postoperative pain after ligament reconstruction. They found that 63% of patients with a ChrismanSnook procedure had some degree of pain, although only 5% described this as severe and 83% of patients after an Evans repair described some degree of pain. Despite this pain, the majority of patients were satisfied with their operative result. The Chrisman-Snook operation was found to have the lowest incidence of instability at 12%, while it had the highest degree of loss of inversion at 70%. Radiographically, talar tilt was controlled equally well with the Evans and Chrisman-Snook procedures and much better than with a Watson-Jones procedure. The overall satisfaction rate was 90% or better. They felt that the results of the Chrisman-Snook operation appeared to be superior to those of the other procedures evaluated. This was felt to be because the

188

PETERS ET AL.

procedure better duplicated the normal anatomy of the lateral ankle ligament complex. Biomechanical Evaluation of Ligament Reconstructions

The primary evaluation of these repairs has been carried out by clinical evaluation and patients' subjective results. Only more recently has an effort been made to evaluate patients more objectively. The question of loss of power due to sacrifice of the peroneus brevis tendon has been addressed by Cybex testing of patients. A comparison between 10 patients who sacrificed the whole peroneus brevis tendon for an Evans reconstruction and 10 patients who sacrificed one half of this tendon for the Chrisman-Snook reconstruction has been made." These authors concluded that although there was a loss of power in the operated ankle as compared with the normal ankle, there was no statistically significant difference in the two types of repairs. All ankles were shown to be weaker than the normal ankle; however, this did not reach the accepted, clinically significant, side to side difference of a 10% reduction in power. Biomechanical information regarding reconstruction of the ligaments has been reported recently. 69 The ATFL has been shown to be the weakest of the lateral ankle ligaments with approximately half the strength of the CFL, while the CFL has been shown to be approximately twice as elastic as the other ligaments. It would seem, therefore, that any reconstruction that replaces the two ligaments with a graft of identical biomechanical characteristics would alter the biomechanics of the ankle joint. The isometricity of these reconstructions has also been addressed and found to be lacklnq." Further biomechanical testing of these reconstructions for assessment of stress and strain patterns as compared with the normal ligaments or ligament repairs would be most welcome. Results of Anatomical Operative Repairs

The possibility of direct suture of the lateral ankle ligaments long after injury was first reported by Brostrorn." He reported that the ligamentous tissue remained intact with the ends encased in scar tissue, but available for repair. Brostrom reported on several methods of repairing these ligaments, including direct suture of the torn ends as well as imbrication of the ligament or direct suture to bone." Other authors have agreed that ligamentous material remains present after injury; however, they note that the ends are not necessarily easy to find and have often healed together, although in an elongated fashion. Therefore, they have recommended shortening and imbrication, repairing to bone troughs, or reinforcement with local tissues. 1 ,27 ,40 ,42 Technically, the lateral ankle ligaments are exposed

Foot & Ankle/Vol. 12, No. 3/December 1991

through a short incision directly over the area of the lateral ligaments. The ATFL and CFL are identified, exposed, and most often found healed in an elongated fashion. The ligaments are divided near the fibula, thereby exposing the joint for inspection. Repair is accomplished in some cases by simple overlap and direct suture or, alternatively, by repair to a trough created in the fibula together with overlap of redundant tissue. Gould et al.27 advocated reinforcing the ATFL repair with the extensor retinaculum and the CFL repair with the lateral talocalcaneal ligament. Overall, six clinical series reporting on 460 ankle repairs are available for review. 1 ,8 ,27 ,40 ,42 ,83 The results indicate that good and excellent outcomes can be achieved in 87% to 95% of patients. The patients had been followed for a period ranging from 2 to 6 years. Modifications in the actual technique of repair have included reinforcement with local tissue, such as the extensor retinaculum or the lateral talocalcaneal ligarnent," or transposition of the periosteal ligamentous flap of tissue more proximally and repairing it directly to the fibula.' The largest single series has been reported on 152 ankles with an average follow-up of 6 years by Karlsson et al.40 These patients were treated by dividing the ligaments, imbricating them, and repairing them by direct suture repair. Good and excellent results were reported in 87% of the patients. Of the 140 patients who had been involved in sports, 120 were able to return to sports with no deterioration in function evident. These same authors" reported on a series of 60 ankles treated by a slightly different technique. The follow-up was shorter at only 3% years, but the results were essentially the same, with 88% of patients achieving good and excellent results. In this series, the shortened ligament was repaired directly to a trough created in the bone, following which imbrication of the redundant ligament was carried out. Consistent findings through the two series was that the small percentage of patients with fair and poor results suffered due to residual mechanical instability. Three factors were found to consistently predict poor outcome. Patients with a history of 10 years of instability prior to surgery and generalized joint hypermobility tended to do poorly. In patients in whom the repair was directed only at the ATFL and the CFL was not repaired, the incidence of fair and poor results increased to 25%. These predictors had an additive effect on the outcome that the patient achieved. Proponents of this technique of anatomical lateral ankle ligament repair described the advantages as being ease and rapidity of performance. No normal tissues are sacrificed in order to accomplish this repair and the result is a more anatomic lateral ankle ligament

Foot & Ankle/Vol. 12, No. 3/December 1991

complex. Only one report is available in which reconstructions are compared directly to ligament repairs." These authors reported a 90% success rate using either a direct ligament repair or the Evans reconstruction. The patients with the Evans procedure had been followed for a longer period of time. The authors felt that direct ligament repair was both simpler and easier, and did not preclude one from doing the reconstruction at a later date should the repair fail. No biomechanical evaluation of repairs has been published to our knowledge. A modification of the direct ligamentous repair was proposed by Hawkins." This involved an arthroscopic technique in which the lateral aspect of the talus was abraded so that the ATFL could be shortened via percutaneous stapling. Twenty-four cases were reported with 2- to 5-year follow-up. Of these, 23 patients were felt to have a stable ankle at the time of clinical examination. No objective data were reported. No effort was made to repair the CFL in these patients. POSTOPERATIVE MANAGEMENT

Management of the patient after surgery is not reported in great detail. Casting is widely practiced and varies from 4 weeks 27,48,77 to 8 weeks." The most common protocol involved 2 to 3 weeks of nonweightbearing, followed by 3 to 5 weeks in a short leg walking cast.5,11,14,26,28,32,42,49,51,57,59,72,81,82 In some cases, postoperative management is not discussed. 2,24,3o,56,66,67,78 Intensive physical therapy is recommended by manyB,26,28,34,42,49,61,72,81 for a period of as much as 12 weeks. Several authors specifically mention physical therapy as unnecessary or not used. 18,57,59 A return to sport was possible as early as 12 weeks after ligament repair." Protection of the repair or reconstruction after rehabilitation, especially during sports, is not mentioned. CONCLUSIONS

The evolution of treatment for chronic lateral ankle instability is similar to that of many other conditions in orthopaedic surgery. The problem is recognized as a clinical one by skilled diagnosticians and treatment is devised on a clinical basis by adventuresome surgeons. Small clinical trials demonstrate success, following which there is wider acceptance of these procedures. Only after the procedures have been tried for some time are more objective evaluations attempted and carried out. More recently, the explosion in technology has allowed increasingly sophisticated biomechanical evaluation of the procedures that have been known and used for a long time. Only now is the investigation of ankle ligament injury and surgery reaching the stage

CHRONIC LATERAL ANKLE INSTABILITY

189

of rigorous testing using these new and sophisticated tools. The indications for operative treatment and the expected outcome have been more clearly delineated than those for nonoperative treatment. Bracing has been shown to be of prophylactic value in preventing recurrent injury. The natural history of chronic ankle instability and the efficacy of these techniques in preventing late arthritis is unknown. Ankle ligament repairs and reconstructions both have very similar high rates of good and excellent clinical outcomes in published retrospective clinical series. Patients should expect a greater then 90% chance of having their mechanical instability corrected. There may be some degree of minor aches and complaints in the ankle after stressful activities. The incidence of these complaints may be as high as 50% to 70% after ligament reconstructions, regardless of the technique of reconstruction, but does not appear to significantly affect the reported outcome. In comparative, but not randomized, studies, the Chrisman-Snook reconstruction seems to be slightly better than other reconstructions for stability, but sural nerve injury remains a concern. The reconstructive techniques themselves have some biomechanical abnormalities that appear to lead to late deterioration in the expected outcome and may contribute to late ankle joint arthritis. Complaints after reconstructions can be related either to stiffness after the reconstruction or to failure of the reconstruction due to laxity. Long-term clinical follow-ups of ligament repairs are limited at this time. Follow-up studies of these patients for 5 to 7 years indicate good results, with no evidence of deterioration at time of follow-up. These results are comparable to those of reconstructions. Biomechanically, on a theoretical basis, these repairs would seem to have the advantages of being more anatomical and more isometric. Only longer follow-up will determine whether this will lead to less late deterioration and degenerative arthritis. Many of the reports of these procedures presented suffer from lack of standardization and poor methodology. Future reports mustinclude more rigorous and objective reporting of operative indications and postoperative management. Randomized prospective studies and more precise objective evaluations will be necessary to determine Whether one of these procedures or principles is truly superior to the others. Future research efforts should be addressed at developing more objective clinical evaluations using newer technology, such as instrumented tilt boards to assess patient reaction times after various treatments. A longterm follow-up of ankle ligament repairs to assess for late deterioration would be helpful. Research into the

190

PETERS ET AL.

various biomechanical parameters of the normal lateral ankle ligaments and repairs or reconstructions lags behind that of other joints. Graft strength and isometricity compared with repairs remains to be determined. Based on our review of the literature, we are presently recommending anatomical repair of the ligaments when surgery is indicated. This repair consists of repairing the ATFL and CFL to a trough created in the fibula, with imbrication of the proximal portion over the repaired distal portion of the tendon. Generalized joint hypermobility and a greater than 10-year time from injury to repair, resulting in significant arthritis, are relative contraindications to having an anatomical repair. In these patients, a reconstruction can be considered. Reconstruction of lateral ankle ligaments in moderately arthritic joints is more successful than repair, with 60% compared with 40% good results. 30 ,42 Reconstruction is also an excellent alternative in a failed anatomical repair. The reconstruction currently recommended is the Chrisman-Snook reconstruction, based on its ability to reconstruct both the ATFL and the CFL. Nonoperative management should be attempted prior to surgery in most cases of chronic ankle instability.

REFERENCES 1. Ahlgren, 0., and Larsson, S.: Reconstruction for lateral ligament injuries of the ankle. J. Bone Joint Surg., 71B:300-303, 1989. 2. Anderson, M.E.: Reconstruction of the lateral ligaments of the ankle using the plantaris tendon. J. Bone Joint Surg., 67A:930934,1985. 3. Andreasson, G., Edberb, B., Peterson, L., and Renstrom, P.: Mechanical function analysis of tape. Lakartidningen, 77:36283629,1980. 4. Balduini, F.C., Vegso, J.J., Torg, J.S., and Torg, E.: Management and rehabilitation of ligamentous injuries to the ankle. Sports Med., 4:364-380,1987. 5. Barbari, S.G., Brevig, K., and Egge, T.: Reconstruction of the lateral ligamentous structures of the ankle with a modified Watson-Jones procedure. Foot Ankle, 7(6):362-368, 1987. 6. Boruta, P.M., Bishop, J.O., Braly, W.G., and Tullos, H.S.: Acute lateral ankle ligament injuries: a literature review. Foot Ankle, 11(2):107-113,1990. 7. Brooks, S.C., Potter, B.T., and Rainey, J.B.: Treatment for partial tears of the lateral ligaments of the ankle: a prospective trial. Br. Med. J., 282:606-607,1981. 8. Brostrom, L.: Sprained ankles: VI. Surgical treatment of "chronic" ligament ruptures. Acta Chir. Scand., 132:551-565, 1966. 9. Brostrom, L., and Sundelin, P.: Sprained ankles: IV. Histologic changes in recent and "chronic" ligament ruptures. Acta Chir. Scand., 132:248-253,1966. 10. Burri, C., and Neugebauer, R.: Carbon fiber replacement of the ligaments of the shoulder girdle and the treatment of lateral instability of the ankle joint. Clin. Orthop., 196:112-117, 1985. 11. Chrisman, O.D., and Snook, G.A.: Reconstruction of lateral ligament tears of the ankle. An experimental study and clinical evaluation of seven patients treated by a new modification of the Elmslie procedure. J. Bone Joint Surg., 51A:904-912, 1969. 12. Clanton, T.O.: Instability of the subtalar joint. Orthop. Clin. North Am., 20(4):583-591, 1989.

Foot & Ankle/Vol. 12, No. 3/December 1991 13. Colville, M.R., Marder, R.A., Boyle, J.D., and Zarins, B.: Reconstruction of the lateral ankle ligaments: a biomechanical analysis. Orthop. Trans., 11:485,1987. 14. Conlin, F.D., Johnson, P.G., and Sinning, J.E.: The etiology and repair of rotary ankle instability. Foot Ankle, 10(3):152-155, 1989. 15. Dockery, G.L., Christensen, J.C., and Lanzer, W.L.: Lateral ankle stabilization using bovine collagen material: xenograft bioprothesis, model GR. J. Foot Surg., 29(1):13-24, 1990. 16. Ekstrand, J.: Soccer Injuries and Their Prevention. Ph.D. Thesis, Linkoping University, 1982. 17. Elmslie, R.C.: Recurrent subluxations of the ankle joint. Ann. Surg., 100:364-367, 1934. 18. Evans, D.L.: Recurrent instability of the ankle-a method of surgical treatment. J. R. Soc. Med., 46:343-344,1953. 19. Freeman, M.A.R.: Instability of the foot after injuries to the lateral ligament of the ankle. J. Bone Joint Surg., 47B:669-676, 1965. 20. Freeman, M.A.R., Dean, M.R.E., and Hanham, I.W.F.: The etiology and prevention of functional instability of the foot. J. Bone Joint Surg., 47B:678-685, 1965. 21. Garrick, J.G.: The frequency of injury, mechanism of injury and epidemiology of ankle sprains. Am. J. Sports Med., 5(6):241242,1977. 22. Garrick, J.G., and Requa, R.K.: Role of external support in the prevention of ankle sprains. Med. Sci. Sports Exerc., 5:200-203, 1973. 23. Gibson, A.: Operation for recurrent subluxation of the ankle joint. J. Bone Joint Surg., 32B:751, 1950. 24. Gillespie, H.S., and Boucher, P.: Watson-Jones repair of lateral instability of the ankle. J. Bone Joint Surg., 53A:920-924, 1971. 25. Glick, J.M., Gordon, R.B., and Nishimoto, D.: The prevention and treatment of ankle injuries. Am. J. Sports Med., 4:136-141, 1976. 26. Good, C.J., Jones, M.A., and Livingstone, B.N.: Reconstruction of the lateral ligament of the ankle. Injury, 7:63-65, 1975. 27. Gould, N., Seligson, D., and Gassman, J.: Early and late repair of lateral ligament of the ankle. Foot Ankle, 1(2):84-89, 1980. 28. Green, A.D.L.: Reconstruction for ankle instability in young active adults. J. R. Coli. Surg. Edinb., 30:50-53, 1985. 29. Haig, H.: Repair of ligaments in recurrent subluxation of the ankle joint. J. Bone Joint Surg., 32B:751, 1950. 30. Harrington, K.D.: Degenerative arthritis of the ankle secondary to long-standing lateral ligament instability. J. Bone Joint Surg., 61A:354-361, 1979. 31. Hawkins, R.B.: Arthroscopic stapling repair for chronic lateral instability. Clin. Padiatr. Med. Surg., 4(4):875-883, 1987. 32. Hedeboe, J., and Johannsen, A.: Recurrent instability of the ankle joint: surgical repair by the Watson-Jones method. Acta Orthop. Scand., 50:337-340, 1979. 33. Heilman, A.E., Braly, W.G., Bishop, J.O., Noble, P.C., and Tullos, H.S.: An anatomic study of subtalar instability. Foot Ankle, 10(4):224-228,1990. 34. Hendel, D., Peer, A., and Halperin, N.: A simple operation for correction of chronic lateral instability of the ankle. Injury, 15:115-116,1983. 35. Horstman, J.K., Kantor, G.S., and Samuelson, K.M.: Investigation of lateral ankle ligament reconstruction. Foot Ankle, 1(6):338-342,1981. 36. Jackson, D.W., Ashley, R.L., and Powell, J.W.: Ankle sprains in young athletes. Clin. Orthop., 101:201-215, 1974. 37. Jenkins, D.H.R., and McKibbin, B.: The role of flexible carbonfibre implants as tendon and ligament substitutes in clinical practice. J. Bone Joint Surg., 62B:497-499, 1980. 38. Kannus, P., and Renstrom, P.: Treatment for acute tears of the lateral ligaments of the ankle. J. Bone Joint Surg., 73A:305-312, 1991. 39. Karlsson, J.: Chronic Lateral Instability of the Ankle Joint: A Clinical, Radiological and Experimental Study, Medical Dissertation, Goteborg, 1989.

Foot & Ankle/Vol. 12, No. 3/December 1991 40. Karlsson, J., Bergsten, T., Lansinger, 0., and Peterson, L.: Reconstruction of the lateral ligaments of the ankle for chronic lateral instability. J. Bone Joint Surg., 70A:581-588, 1988. 41. Karlsson, J., Bergsten, T., Lansinger, 0., and Peterson, L.: Lateral instability of the ankle treated by the Evans procedure: a long-term clinical and radiological follow-up. J. Bone Joint Surg., 70B:476-480,1988. 42. Karlsson, J., Bergsten, T., Lansinger, 0., and Peterson, L.: Surgical treatment of chronic lateral instability of the ankle joint. Am. J. Sports Med., 17(2):268-273, 1989. 43. Kjaersgaard-Anderson, P., Sojbjerg, J.O., Wethelund, J., Helmig, P., and Madsen, F.: Watson-Jones tenodesis for ankle instability: a mechanical analysis in amputation specimens. Acta Orthop. Scand., 60(4):477-480, 1989. 44. Kristiansen, B.: Evans' repair of lateral instability of the ankle joint. Acta Orthop. Scand., 52:679-682,1981. 45. Larsen, E.: Experimental instability of the ankle: a radiographic investigation. Clin. Orthop., 204:193-200, 1986. 46. Larsen, E., and Angermann, P.: Association of ankle instability and foot deformity. Acta Orthop. Scand., 61(2):136-139, 1990. 47. Laughman, R.K., Carr, T.A., and Chao, E.Y.: Three-dimensional kinematics of the taped ankle before and after exercise. Am. J. Sports Med., 8:425-431, 1980. 48. Lauttamus, L., Korkala, 0., and Tanskanen, P.: Lateral ligament injuries of the ankle. Surgical treatment of late cases. Ann. Chir. Gynaecol., 71:164-167,1982. 49. Leach, R.E., Namiki, 0., Paul, R., and Stockel, J.: Secondary reconstruction of the lateral ligaments of the ankle. Clin. Orthop., 160:201-211, 1981. 50. Lee, H.G.: Surgical repair in recurrent dislocation of the ankle joint. J. Bone Joint Surg., 39A:828-834, 1957. 51. Lucht, U., Yang, P.S., and Termansen, N.B.: Lateral ligament reconstruction of the ankle with a modified Watson-Jones operation. Acta Orthop. Scand., 52:363-366, 1981. 52. Mack, R.P.: Ankle injuries in athletes. Clin. Sports Med., 1:7184,1982. 53. McConkey, J.P.: Ankle sprains, consequences and mimics. Med. Sport Sci., 23:39-55, 1987. 54. McCullouch, P.G., Holden, P., Robson, D.J., Rowley, 0.1., and Norris, S.H.: The value of mobilization and non-steroidal antiinflammatory analgesia in the management of inversion injuries of the ankle. Br. J. Clin. Pract., 2:69-72,1985. 55. Nilsonne, H.: Making a new ligament in ankle sprain. J. Bone Joint Surg., 31A:380-381, 1949. 56. Orava, S., Jaroma, H., Weitz, H., Loikkanen, T., and Suvela, M.: Radiographic instability of the ankle joint after Evans' repair. Acta Orthop. Scand., 54:734-738,1983. 57. Ottosson, L.: Lateral instability of the ankle treated by a modified Evans procedure. Acta Orthop. Scand., 49:302-305, 1978. 58. Rarick, G.L., Bigley, G., and Karst, R.: The measurable support of the ankle joint by conventional methods of taping. J. Bone Joint Surg., 44A:1183-1190, 1962. 59. Rechtine, G.R., McCarroll, J.R., and Webster, D.A.: Reconstruction for chronic lateral instability of the ankle: a review of twenty eight surgical patients. Orthopedics, 5(1):46-50, 1982. 60. Renstrom, P., Wertz, M., Incavo, S., and Pope, M.: Strain in the lateral ligaments of the ankle. Foot Ankle, 9(2):59-63, 1988. 61. Riegler, H.F.: Reconstruction for lateral instability of the ankle. J. Bone Joint Surg., 66A:336-339, 1984. 62. Rovere, G.D., Clarke, T.J., Yates, C.S., and Burley, K.: Retrospective comparison of taping and ankle stabilizers in preventing ankle injuries. Am. J. Sports Med., 16(3):228-233, 1988.

CHRONIC LATERAL ANKLE INSTABILITY

191

63. Ruth, C.J.: The surgical treatment of injuries of the fibular collateral ligament of the ankle. J. Bone Joint Surg., 43A:229-239, 1961. 64. St. Pierre, R., Allman, F., Bassett, F.H., Goldner, J.L., and Fleming, L.L.: A review of lateral ankle ligamentous reconstructions. Foot Ankle, 3(2):114-123, 1982. 65. Sammarco, G.J., and DiRaimondo, C.V.: Surgical treatment of lateral ankle instability syndrome. Am. J. Sports Med., 16(5):501-511, 1988. 66. Sammarco, G.J., and DiRaimondo, C.V.: Chronic Peroneus Brevis tendon lesions. Foot Ankle, 9(4):163-170, 1989. 67. Savastano, A.A., and Lowe, E.B.: Ankle sprains: surgical treatment for recurrent sprains. Am. J. Sports Med., 8(3):208-211, 1980. 68. Sefton, G.K., George, J., Fitton, J.M., and McMullen, H.: Reconstruction of the anterior talofibular ligament for the treatment of the unstable ankle. J. Bone Joint Surg., 61B:352-354, 1979. 69. Siegler, S., Block, J., and Schneck, C.D.: The mechanical characteristics of the collateral ligaments of the human ankle joint. Foot Ankle, 8(5):234-242,1988. 70. Silver, C.M., and Deutsch, S.D.: Evans repair of lateral instability of the ankle. Orthopedics, 5(1):51-56,1982. 71. Snook, G.A., Chrisman, 0.0., and Wilson, T.C.: Long-term results of the Chrisman-Snook operation for reconstruction of the lateral ligaments of the ankle. J. Bone Joint Surg., 67A:1-7, 1985. 72. Solheim, L.F., and Denstad, T.F.: Chronic lateral instability of the ankle: a method of reconstruction using the Achilles tendon. Acta Orthop. Scand., 51:193-196,1980. 73. Storen, H.: A new method for operative treatment of insufficiency of the lateral ligaments of the ankle joint. Acta Chir. Scand., 117:501-509,1959. 74. Tindall, S.F., and Heaney, S.H.: Repair of the lateral ligaments of the ankle by the Evans technique. J. Bone Joint Surg., 58B:133,1976. 75. Ting, G., and Levitsky, D.R.: Levitsky ankle stabilization procedure. J. Foot Surg., 28(3):233-236,1989. 76. Tropp, H.: Functional Instability of the Ankle Joint. Medical Dissertation, Linkoping University, 1985. 77. Vainionpaa, S., Kirves, P., and Laike, E.: Lateral instability of the ankle and results when treated by the Evans procedure. Am. J. Sports Med., 8(6):437-439, 1980. 78. Van der Rijt, A.J., and Evans, G.A.: The long-term results of Watson-Jones tenodesis. J. Bone Joint Surg., 66B:371-375, 1984. 79. Watson-Jones, R.: Fractures and Other Bone and Joint Injuries. Baltimore, Williams & Wilkens, 1940, pp. 580-583. 80. Watson-Jones, R.: Recurrent forward dislocation of the ankle joint. J. Bone Joint Surg., 34B:519, 1952. 81. Younes, C., Fowles, J.V., Fallaha, M., and Antoun, R.: Longterm results of surgical reconstruction for chronic lateral instability of the ankle: comparison of Watson-Jones and Evans techniques. J. Trauma, 28(9):1330-1334, 1988. 82. Zenni, E.J., Greter, M., Krieg, J.K., Lambert, M.B., and Florez, R.: Lateral ligamentous instability of the ankle: a method of reconstruction by a modified Watson-Jones technique. Am. J. Sports Med., 5(2):78-83.1977. 83. Zwipp, H., and Tscherne, H.: Zur behandlung der chronischen antero-Iateralen instabilitat des oberen sprunggelenkes: derekte bandrekonstruktion-Periostlappenplastik-Tenodese. Unfallheilkunde, 87:405-415, 1984.