Ankle Injuries: Anatomical and Biomechanical Considerations Necessary for the Development of an Injury Prevention Program

0196-6011 /80/0103-0171$02.00/0 THE JOURNAL OF ORTHOPAEDIC AND SPORTS PHYSICAL THERAPY Copyright O 1980 by The Orthopaedic and Sports Medicine Sections of the American Physical Therapy Association Ankle Injuries: Anatomical and Biomechanical Considerations Necessary for the Development of an Injury Prevention Program GREG KAUMEYER,* MS, PT, ATC, TERRY MALONE,? MS, PT, ATC Copyright 1980. All rights reserved. This article describes the anatomical and biomechanical principles necessary for the development of an ankle injury prevention program. The structures of the talocrural joint and the subtalar joint are discussed in detail. The biomechanics of these two joints are discussed and their relationship elucidated. The!igamentous structures of the ankle are discussed in detail. Evaluation of the ankle is discussed in conjunction with mechanisms of athletic injuries. Pertinent principles necessary for the development of an injury prevention program for the ankle are presented. Ankle injuries are nearly synonymous with athletic participation. Blyth and Mueller' reported that 15.3% of all high school football injuries involved the ankle, whereas 42% of all high school football players had a.history of a previous ankle injury. Garrick and Requa6 determined that 28% of intramural basketball injuries at the University of Washington involved the ankle. Hence, there seems to be a tremendous need for an ankle injury prevention program. The prevention program should be based upon: 1) the anatomy of the ankle-relating musculoskeletal structure to ankle stability; 2) the biomechanics of the ankle; and 3) the mechanisms of ankle injuries. These areas will be discussed briefly herein and are the basis of the prevention program. ANATOMY Bony Structure The ankle joint is formed by the dome of the talus fitting into a mortise formed by the tibia and the fibula. In many people, the anterior portion * Director of Sports Physical Therapy, Rehabilitation Services of Mid- America, Inc., Joliet, IL. t Coordinator of P.T. Services. Duke University. Department of Surgery, Division of Orthopaedic Surgery, Section of Sports Medicine. Durham, NC. of the talus is wider than the posterior portion. The malleoli also converge posteriorly. The articular surfaces of the malleoli are in close approximation of the talus in all positions from dorsiflexion to plantar flexioni0 (Fig. 1). The subtalar joint must be considered with the ankle since the calcaneofibular and tibiocalcaneal ligaments cross this joint, and subtalar motions have a direct effect upon ankle injuries. The distal projection of the lateral malleolus acts to limit the amount of eversion within the ankle mortise. The medial malleolus does not project as far distally on the talus and thus allows a greater amount of inversion. The movements that occur at the ankle joint and subtalar joint are combined movements. Inversion of the heel simultaneously occurs with plantar flexion during weight-bearing in the normal indi~idual.~ During examination with the leg fixed, the foot deviates laterally during dorsiflexion and medially during plantar flexion. This indicates that movement is occurring at both the ankle and the subtalar joints. Ligaments and Capsule The ankle joint is surrounded by a fibrous capsule. This capsule is weakest anteriorly and posteriorly, thus allowing plantar flexion and dor-

172 KAUMEYER AND MALONE JOSPT Vol. 1, No. 3 Copyright 1980. All rights reserved. Fig. 1. A normal A-P roetgenogram demonstrating the relationship of the articulating surfaces of the tibia, fibula, and talus. Fig. 2. The lateral ligamentous structures of the ankle. siflexion. The medial and lateral sides are strengthened by well-defined ligamentous structures. The lateral side of the ankle is composed of three major ligamentous structures: 1) anterior talofibular ligament; 2) calcaneofibular ligament; and 3) posterior talofibular ligament (Fig. 2). The individual ligaments provide lateral stability depending upon the position of the When the foot is in the plantar flexed position, the anterior talofibular ligament is perpendicular to the talus and provides stability against excessive inversion. The calcaneofibular ligament is perpendicular to the talus when the ankle is in slight dorsiflexion and provides stability against inversion in this position. Inversion is most limited in dorsiflexion due to the alignment of the ligaments. This is known as the closed packed position.i3 The posterior talofibular ligament helps resist forward dislocation of the leg on the foot. The posterior talofibular ligament is the strongest of the lateral ligaments. The deltoid ligament provides support to the medial side of the ankle. This is the strongest of the collateral ligaments and can be divided into four portions: 1) tibionavicular, this portion is anterior and superficial; 2) anterior tibiotalar, this portion is anterior and deep; 3) tibiocalcaneal, this portion is posterior and superficial; and 4) posterior tibiotalar, this portion is posterior and deep (Fig. 3). THE MUSCULATURE The musculature that traverses the ankle supports the ligamentous structures in maintaining the stabilityof the ankle and subtalar joints. The anterior and posterior muscle groups provide the strength for dorsiflexion and plantar flexion and receive some assistance in these movements from the medial and lateral musculature. The peroneus longus and peroneus brevis assist in supporting the ankle laterally. These originate in the peroneal compartment of the leg and pass posteriorly and inferiorly to the lateral malleolus. The peroneus brevis is the more anterior of the two peroneal tendons with both tendons covering the posterior talofibular ligament and part of the calcaneofibular ligament. The strength of Fig. 3. The medial ligamentous structures of the ankle

JOSPT Winter 1980 ANKLE INJURIES 173 Copyright 1980. All rights reserved. these muscles is most important in the absorption of stress and thus provides support to the lateral ligaments. The tendons of the tibialis posterior, flexor hallucis longus, and flexor digitorum longus pass posteriorly and inferiorly to the medial malleolus. These three muscles originate from the posterior co'mpartment of the leg and are important in medial stabilization. The tibialis posterior fits in a groove in the medial malleolus and covers the posterior part of the deltoid ligament. BIOMECHANICS An estimate of the axis of motion of the ankle joint can be done by constructing a line that passes just distal to the tips of the medial and lateral malle~li~~'~ (Fig. 4). This axis is an oblique line in comparison with the surface on which the person is standing and varies from individual to individual. When the foot is nonweightbearing, this oblique axis causes the foot to rotate inward when the ankle is plantar flexed and outward when the ankle is dorsiflexed (Figs. 5 and 6). During weight-bearing, this oblique axis will cause the leg to be internally rotated during dorsiflexion and externally rotated during plantar flexion. The movement between the talus and calcaneus occurs about a single oblique axis. This axis is not stationary and is oriented in an an- teroposterior direction. The position of this single axis as projected in both the sagittal and transverse planes varies considerablyg (Figs. 7 and 8). The two axes of the ankle and subtalar joints lie in different planes. Since the calcaneofibular ligament crosses both of these joints, it must be positioned so not to restrict normal motions occurring at either joint. The fibular attachment of this ligament lies very close to the axis of motion of the ankle joint and, therefore, does not restrict movement at the ankle joint.g The calcaneofibular ligament passes downward and posteriorly from the lateral malleolus to the calcaneus, and it is this construction that allows unrestricted movement at the subtalar joint. The ligament lies on the surface of an imaginary cone whose apex is the intersection of the axis of motion and an extension of the line of the ligamentg (Fig. 9). The calcaneofibular ligament moves along the surface of this imaginary cone during movement at the subtalar joint. MECHANISMS OF INJURY The most common ankle injury is the inversion sprain.5. 7.14.17 Most inversion sprains occur when the foot is plantar flexed, stressing the anterior talofibular ligament. The anterior talofibular ligament is injured as it is perpendicular to the movement of the talus. If the stress causing Fig. 4. A clinical estimate of the axis of motion at the ankle joint.

1 74 KAUMEYER AND MALONE JOSPT Vol. 1, No. 3 Copyright 1980. All rights reserved. Fig. 5. The foot is rotated slightly inward during plantar flexion. Fig. 7. Variations of the axis of motion of the subtalar joint as projected in the sagittal plane. Fig. 8. Variations in the axis of motion of the subtalar joint as projected in the transverse plane. Fig. 6. The foot is rotated slightly outward during dorsiflex- the injury is forceful enough to cause a substantial tear of the anterior talofibular ligament, the calcaneofibular ligament can be damaged because it will be the next ligamentous structure to resist the stress. The calcaneofibular ligament will be injured separately if the foot is inverted with the ankle near the neutral position, since this ligament will be more nearly perpendicular to the stress in this position. If the anterior talofibular ligament is torn, there will be a lateral

JOSPT Winter 1980 ANKLE INJURIES 175 Copyright 1980. All rights reserved. Fig. 9. The calcaneofibular ligament lies on the surface of an joint. instability only when the foot is plantar flexed. If both the anterior talofibular ligament and calcaneofibular ligament are torn, there will usually be lateral instability of the ankle joint at all positions. It is possible to tear both of these ligaments and still have a stable ankle when it is dorsiflexed. An unstable ankle could also be due to an injury of the anterior tibiofibular and posterior tibiofibular ligaments. The eversion type of injury to the ankle is seen less frequently. The movement of eversion is much more limited due to the length of the lateral malleolus. Any increased stress is limited by this bony block and frequently causes a compression fracture of the fibula. The medial ligaments are much stronger than the lateral ligaments, and any sufficient tear of these ligaments is usually accompanied by a fracture of the fibula or tibia. It is imperative to rule out a fracture in any ankle injury. Fractures of the fibula, tibia, and talus may be present. Avulsion fractures of the peroneus brevis from the base of the fifth metatarsal may be seen with inversion injuries. PREVENTION With this basic anatomical and biomechanical background, a prevention program can be designed to decrease the incidence of ankle injuries. In considering an adequate prevention program, the following areas should be considered: imaginary cone allowing unrestricted movement at the subtalar 1) screening of athletes; 2) exercise program; 3) taping or wrapping; 4) shoe type and size; and 5) playing surface. Screening of Athletes The screening program is used to identify those individuals who are susceptible to ankle injuries. Glick'' determined that football players who have a talar tilt of 5 degrees or more have the highest incidence of ankle injuries. Although this can only be accurately assessed by using stress roentgenograms, a gross clinical assessment of talar tilt can be used in a screening program. The lateral stability of the ankle can be tested by fixating the leg with one hand, and by placing the other hand on the cuboid bone forcing the foot into inversion and noting the talar tilt (Fig. 10). It is necessary to test the talar tilt with the foot in plantar flexion and dorsiflexion so that the integrity of the anterior talofibular ligament and the calcaneofibular ligament can be tested. This can be compared to the opposite ankle if it has not been previously injured, to determine the normal stability of the ankle mortise. If both ankles have been injured previously, the estimated talar tilt should be noted on each ankle. Any ankle that appears to demonstrate instability clinically should be evaluated by stress roentgenograms. Bosein et al.' determined that there is a high

176 KAUMEYER AND MALONE JOSPT Vol. 1, No. 3 football and basketball, where high incidences of ankle injuries have been reported, all the athletes should be on an exercise program. This program should be designed to maintain a high level of strength and flexibility. Taping or Wrapping Copyright 1980. All rights reserved. Fig. 10. The clinical assessment of the lateral stability of the ankle. incidence of injury to the ankle that has sustained previous injury. The screening of the athletes should note whether there is a history of previous ankle injury. It was also found that peroneal muscle weakness was a significant factor demonstrated by those exhibiting chronic ankle symptoms. Peroneal strength can be assessed through manual muscle testing, but more objective data can be obtained by using an isokinetic testing device for inversion and eversion. The flexibility of the gastrocnemius muscle should be assessed since it can limit dorsiflexion and make the ankle more susceptible to injury. Cahil13 states that a tight heel cord makes the ankle more susceptible to a lateral injury because the ankle has limited dorsiflexion; the supination at the subtalar joint will be increased more than that of the normal ankle and thus place additional stress on the lateral ligaments. Exercise Program Those who are found to be susceptible to ankle injuries through the screening process should be placed on an exercise program. This program should be designed to decrease the athlete's probability of injury. In sports, such as Ankle wrapping or taping has been used in athletics to provide physical and psychological support for the prevention of ankle injuries. The ankle wrap is a nonelastic, cloth-like, reuseable material which is placed over the sock in a certain r at tern.^ Prophylactic wrapping of the ankle can be used, allowing decreased cost compared to prophylactic taping. The ankle wraps can also be applied much faster and easier than tape. Taping for prevention is usually done over a foam-like underwrap that protects the skin. Individuals who have had a previous ankle injury are taped directly to the skin since this provides more supporting strength than does prophylactic taping or wrapping.i5 It was determined by Rarick et al." that ankle taping using a basketweave combined with a figure eight and heel locks limits inversion more effectively than do other methods of ankle taping. Taping does not replace rehabilitation of the injury. The tape or wrap should be applied before each practice session because the support provided decreases during a~tivity.'~. '* Ankle taping has a minimal effect upon the athlete's performance. There is no difference in the speed or agility whether a person is taped or ~ntaped.".~' There is a decrease in the jumping ability at the 0.05 level in the athlete who is taped as compared to when he is ~ntaped."~" The effectiveness of ankle wraps and taping for the prevention of ankle injuries has been reported in several studies. Garrick and Requa6 determined that there was a decreased incidence in ankle injuries of basketball players who had their ankles taped. Simonig found that there was a decrease in the incidence of ankle injuries in football players when using tape or a wrap. There was no difference in the incidence of injury between those who had their ankles taped and those who had their ankles wrapped. This taping or wrapping was of a prophylactic nature. Shoe Type and Size There are many factors to consider when determining what shoes should be used for a specific sport. The type of shoe used and its construction has been shown to affect the incidence

JOSPT Winter 1980 ANKLE INJURIES 177 Copyright 1980. All rights reserved. of ankle injuries. The sole of the shoe should be rigid to prevent other foot problems. Garrick and Requa6 found that high-top basketball shoes reduced the incidence of ankle injuries when compared to low-cut basketball shoes. Torg2' found that the long cleats on football shoes caused fixation of the shoe to the natural grass playing surface. The use of the soccer-type shoe has been shown to reduce the incidence of knee injuries as compared with the regulation football shoes. The proper shoe size is important in preventing excessive movement of the foot within the shoe. An improperly fitting shoe can result in foot and ankle injuries. The proper shoe size is determined by 1) the length from heel to toe, 2) the width across the metatarsal arch, and 3) the length from the heel to the first metatarsal head. Playing Surface The type of playing surfaces and the incidence of injuries on the different surfaces is a currently debated issue. The type of shoe used on specific types of surfaces has a direct relationship upon the incidence of inj~ry.'~ The condition of the natural turf field can greatly affect the incidence of ankle injuries. Depressions and holes on the playing surface can increase the incidence of ankle injuries. CONCLUSION The high incidence of ankle injuries during athletic competition indicates the need for a prevention program to reduce the number and severity of injuries. The development of a prevention program should be based upon anatomic and biomechanical considerations. The prevention program should be developed to fit the needs of each athletic situation. ACKNOWLEDGMENT Figures 4, 7, 8, and 9 were reproduced with permission from lnman VT: The Joints of the Ankle. Williams 8 Wilkins Co., O 1976. REFERENCES 1. Blyth CS. Mueller FO: An epidemiologic study of high school football injuries in North Carolina. Washington, DC. US Government Printing Office, 1974, p 67 2. Bosein WR, Staples OS, Russell SW: Residual disabilities following acute ankle sprains. J Bone Joint Surg. 37-A:1237. 1955 3. Cahill BR: Chronic orthopedic problems in the young athlete. J Sports Med, 1 :36-39. 1973 4. Davies GJ: The ankle wrap: variation from the traditional. Ath Train. 12:194-197, 1977 5. Floriana LD: Ankle injury mechanism and treatment guide. Phys Sports Med. 4(9):72-78, 1976 6. Garrick, Requa RK: Role of external support in the prevention of ankle injuries. Med Sci Sports, 5200-203. 1973 7. Garrick JG: Ankle injuries: frequency and mechanism of injury. Ath Train, 10:109-111. 1975 8. Glick JM: A study of ligamentous looseness and its relation to injury. Proc LeRoy Abbott Orthop Soc, 1 :34-39, 1971 9. lnman VT: The Joints of the Ankle. Williams 8 Wilkins Co., Baltimore, 1976, pp 18, 45-80 10. lnman VT: DuVries surgery of the foot. CV Mosby Co. St. Louis. 1973, pp 15-22 1 1. Juvenal JP: The effects of ankle taping on vertical jumping ability. Ath Train, 7:146-149. 1972 12. Leonard MH: Injuries of the lateral ligaments of the ankle. J Bone Joint Surg. 31-A:373-377, 1949 13. MacConaill MA. Basmajian JV: Muscles and Movements. Williams 8 Wilkins Co, Baltimore, 1969, p 78 14. Mack RP: Ankle injuries in athletics. Ath Train 10:94-95. 1975 15. Malina RM, et al: Effect of exercise upon the measurable supporting strength of cloth and tape ankle wraps. Res Quart, 34: 158-165. 1963 16. Mayhew JL: Effects of ankle taping on motor performance. Ath Train. 7:lO-11, 1972 17. O'Donoghue DH: Treatment of injuries to athletes. WB Saunders Co. Philadelphia. p 1970. p 61 4 18. Rarick GL, et al: The measurable support of the ankle joint by conventional methods of taping. J Bone Joint Surg. 44-A:1183-1 190, 1962 19. Simon JE: Study of the comparative effectiveness of ankle taping and ankle wrapping on the prevention of ankle injuries. Ath Train. 4:6-7. 1969 20. Staples OS, Ligarpentous injuries of the ankle joint. Clin Orthop, 42:21-34. 1965 21. Thomas JR, Cotten DJ: Does ankle taping slow down athletes? Coach Ath, 1971 22. Torg JS: Proper and improper athletic footwear, and its effect on athletic performance. Ath Train. 10:104-106. 1975