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Persistent Pain After Ankle Sprain: Targeting the Causes

Hugh L. Bassewitz, MD; Matthew S. Shapiro, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 12 - DECEMBER 97


In Brief: Most lateral ankle sprains heal with conservative treatment. Pain that lasts 6 or more weeks after a sprain may come from inadequate rehabilitation, impingement, occult osteochondral or chondral lesions, peroneal tendon or syndesmosis injury, or lateral instability. Treatment for inadequate rehabilitation includes supervised rehabilitation and home exercise. Surgery is recommended for refractory cases of impingement syndrome. Occult osteochondral or chondral lesions usually require arthroscopic excision or repair. Peroneal tendon injury should be treated conservatively before surgery is considered. The severity of syndesmosis injury determines conservative or surgical measures. Remedies for lateral instability include an ankle brace, physiotherapy, and surgery.

Primary care physicians frequently see patients who have ankle sprains (1). The vast majority of these injuries occur through inversion of the ankle. Among athletes, ankle sprains are the most common injury, and inversion injuries are frequent (2-4). Most patients are treated conservatively, and the outcome is usually satisfactory. However, a subset may continue to experience pain after what appears to be a routine sprain. Understanding the relationship between ankle anatomy, mechanisms of injury, and the range of ankle injuries can help physicians treat patients who are suffering chronic pain after an ankle sprain.

Anatomy and Injury Mechanisms

The degree and type of damage sustained by the ankle depend on the magnitude of the applied force (usually the body weight) and the position of the ankle at the time of injury. The lateral ligament complex of the ankle, which is at risk during forced inversion, consists of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL) (figure 1). The ATFL is a thickening of the lateral capsule and runs horizontally from the anterior distal fibula to insert on the talar neck. The CFL is a discrete, extra-articular, round ligament that originates from the tip of the fibula to span obliquely downward and posteriorly to insert on the calcaneus. These two ligaments work in tandem to support the lateral ankle, depending on the position of the joint. When the ankle is plantar flexed, the ATFL is aligned vertically, parallel to the fibula, and is under tension. Conversely, when the ankle is dorsiflexed, the CFL is in line with the fibula and under tension.

[FIGURE 1]

These ligaments are variably injured, depending on whether the ankle is plantar flexed or dorsiflexed at the time of trauma. The ankle is at highest risk when it is plantar flexed, since the foot has a longer lever arm and there is less inherent bony and ligament stability when the ankle is in this position. Therefore, the ATFL, which is most exposed during plantar flexion, is the ligament most commonly injured. The CFL is injured when the ankle is sprained in dorsiflexion. In most injuries, both ligaments are injured to some extent. The PTFL is considerably stronger than the ATFL and CFL and is not frequently injured (5).

Additional structures support the ankle. The deltoid ligament is a very strong and broad structure that stabilizes the medial side of the ankle. Deltoid ligament injury is much less common than injury to the lateral ligaments, but it can occur with eversion sprains. Strong syndesmotic ligaments hold the distal tibia and fibula together; they allow slight rotational movement of the fibula and can be injured when severe external rotation force is combined with an inversion force. The peroneal tendons (figure 1) run in the peroneal sheath, just posterior to the distal fibula; the tendons and the sheath are vulnerable to injury during ankle trauma.

Most injuries to any of these structures can be treated conservatively (see "Initial Management of Ankle Sprains," below). Even with optimal treatment, however, a few patients will continue to have ankle pain 6 weeks or more after a sprain. Such persistent pain may be caused by insufficient rehabilitation, posttraumatic impingement syndrome, occult osteochondral injury, trauma to the peroneal tendon or syndesmosis, or chronic instability.

Inadequate Rehabilitation

Most patients who have persistent pain after an ankle sprain fall into this group. The major signs and symptoms are stiffness, weakness, and loss of proprioception. Recurrent instability frequently characterizes these injuries, because patients lack the muscular control and coordination to effectively protect their ankle. Because of capsular contracture or intra-articular adhesions and associated end-range pain, patients may lack sufficient range of motion for even normal activities. Weak peroneal muscles may make patients unable to voluntarily or involuntarily evert the foot when it is in a position of danger. Lack of proprioceptive control may delay the involuntary response to an inversion strain and cause reinjury, even with relatively minor stresses.

Formal, rigorous rehabilitation, supervised by a physical therapist in a controlled setting, along with a home exercise program, is suggested to help these patients recover full function. Use of a balance board or mini-trampoline may help these patients strengthen and improve their proprioception. If 6 weeks of therapy fails to solve the patients' problems, a more rigorous workup is warranted.

Impingement Syndrome

Fibrous connective tissue can form in the anterolateral or anteromedial ankle after a sprain. These meniscoid lesions were first described in 1950 and are important to recognize as a cause of chronic anterolateral ankle pain (6). One theory suggests that when the ATFL or CFL is ruptured in its midsubstance, the torn ligament ends enlarge and are responsible for the soft-tissue tesion that becomes impinged (7). Another theory suggests that the synovial impingement tissue is hypertrophic normal tissue from the synovial recess above the lateral talomalleolar joint (8). We believe that this pain may also be related to mild, undetected injury to the anterior tibiofibular ligaments, with fibers from the syndesmosis falling into the lateral aspect of the tibiotalar joint.

Whatever the etiology, abnormal soft tissue and/or bone spurs in the anterior tibiotalar joint can be pinched when the patient dorsiflexes, causing chronic anterolateral ankle pain (figure 2). If anterolateral ankle pain persists for at least 6 months after a sprain despite appropriate conservative treatment and is worse with forced dorsiflexion, impingement syndrome should be suspected.

[FIGURE 2]

We perform a standing impingement test that requires the patient to dorsiflex the ankle maximally while keeping his or her heel in contact with the ground. The angle formed by the back of the leg and the floor is measured with a goniometer. A side-to-side difference of 5° or more suggests impingement.

Radiographs may be normal, although frequently anterior spurs of the tibia or talus are present. Magnetic resonance imaging (MRI) has not proven reliable in detecting this entity.

The current recommended treatment for refractory cases of impingement is ankle arthroscopy, partial synovectomy, and scar tissue debridement. Success rates of 85% or more have been reported (6). We have not found corticosteroid injection before arthroscopy to be helpful.

Occult Osteochondral or Chondral Lesions

A variety of lesions that occur either in the tibial plafond or on the talar dome are described as osteochondritis dissecans, subchondral cysts, or osteochondral lesions of the talus (9). While some of these lesions occur without overt trauma, most occur after an ankle sprain. These lesions typically occur either in the posteromedial or anterolateral portion of the talus and are often, but not always, seen on plain radiographs (figure 3). Sometimes repeat radiographs are necessary to identify the lesion. If the original radiographs are negative and the patient has continued joint pain, we recommend that a second set be taken between 6 and 12 weeks after injury. If radiographs continue to be negative, MRI may be used to evaluate a patient for chondral or osteochondral injury.

[FIGURE 3]

Osteochondral injuries to the talar dome and tibial plafond have been classified by their radiographic appearance: stage 1 is a compressed fracture, which may or may not be visible (2% of all osteochondral injuries); stage 2 is a partially attached, nondisplaced fragment (1%); stage 3 is a completely detached, nondisplaced fragment (13%); stage 4 is a displaced fragment (7%); and stage 5 is a radiolucent defect (77%) (9). When osteochondral injury is recognized as the cause of chronic ankle pain, treatment is usually arthroscopic excision or repair. Prompt recognition and treatment afford the patient the best chance of avoiding late degenerative changes, a common sequela of this type of injury.

Peroneal Tendon Injury

The examiner should suspect a tear of the peroneal retinaculum when a patient gives a history of a dorsiflexion injury associated with a painful snapping sensation. The pain may subside rapidly, but snapping near the lateral malleolus may continue. Swelling will usually persist posterior to the lateral malleolus. The peroneal tendons must be carefully evaluated by examining them as the foot is actively rotated into eversion against resistance, since this position elicits tendon subluxation.

Another subtle injury of the peroneal complex is a longitudinal split of either the peroneus brevis or longus. The symptoms of swelling, popping, and posterior fibular pain will persist (10). Longitudinal splits usually are associated with lateral instability (11).

In a patient with presumptive evidence of peroneal tendon injury, MRI is suggested to confirm the diagnosis. Overt snapping is usually treated operatively. Pain without mechanical symptoms should be treated with a trial of immobilization and nonsteroidal anti-inflammatories prior to considering surgery.

Syndesmosis Injury

The syndesmosis complex consists of the anterior and posterior inferior tibiofibular ligaments, the transverse tibiofibular ligament, and, more superiorly, the interosseous membrane. Along with the medial deltoid ligament, the syndesmosis provides a strong restraint to external rotation forces.

As mentioned above, syndesmosis injury occurs with external rotation injuries, which frequently accompany an inversion sprain. Several studies (12) have cited syndesmotic injury as a cause of chronic ankle pain, disability, and instability. The true prevalence of these injuries is not known, but the prevalence associated with an ankle sprain is estimated to be 1% to 10% (13).

Patients who have a syndesmosis injury present with the typical findings of an ankle sprain, plus supramalleolar edema and pain with passive dorsiflexion and external rotation of the ankle. The three syndesmosis tests will be positive (see "Initial Management of Ankle Sprains," below). In severe injuries with complete rupture of the syndesmosis, radiographs may show widening of the medial clear space and lateral subluxation of the talus. Widening of the mortise from soft tissue injury alone, however, is rare. Radiographs of the entire fibula should be obtained to rule out a high fibular (Maissoneuve) fracture. Stress films may be necessary.

Complete ruptures of the syndesmosis with clinical or radiographic evidence of lateral talar subluxation should be operatively treated with a transverse screw (14). If an occult injury is discovered late, heterotopic ossification at the distal tibiofibular joint may frequently be seen on the x-rays. Complete synostosis, however, is very rare.

Patients who have pain 6 to 8 weeks after an ankle sprain should be reexamined for a syndesmosis injury. While there is no recommended treatment at this point, confirmation of a syndesmotic injury will provide an accurate prognosis and rule out other problems. These injuries typically clear up by themselves, almost always within 8 to 12 weeks of injury.

Lateral Ankle Instability

Patients who complain of swelling, lateral pain and tenderness, and recurrent symptoms of giving way should be suspected of having lateral instability. Instability can result from an incompetent ATFL or CFL or defects in other lateral structures. Paradoxically, persistent instability is one of the less common clinical syndromes after ankle sprain. Radiographic stress views, particularly the inversion-varus stress view, are imperative for diagnosing this condition. The anterior drawer test (see "Initial Management of Ankle Sprains," below) should be performed to measure the integrity of the ATFL; this test is considered by some authors to be more reliable than the inversion test (15).

Symptomatic instability generally occurs in two ways. Some patients experience recurrent sprains during athletic activities. These patients are usually treated with physical therapy and a prophylactic ankle brace during sports activity. Other patients have instability with daily activities. These injuries are more difficult to manage, since patients cannot wear a brace continually. If physiotherapy, proprioception training, and bracing all fail to alleviate symptoms, surgery may be considered. The most common procedures are a direct repair of the ATFL (Brostrom procedure) (16) and a reconstruction of the lateral ligament complex with tendon graft (Christman-Snook procedure).

Other Conditions

If none of the above conditions explains a patient's continued symptoms, several other uncommon conditions should be considered. Reflex sympathetic dystrophy may follow foot and ankle trauma and will be manifested by severe pain of a neurogenic variety along with skin discoloration and temperature change. Pain alleviated by a sympathetic block is the key to diagnosis. We refer patients who have reflex sympathetic dystrophy to a pain management specialist.

Fractures that may be impossible to see on plain radiographs may rarely occur in other tarsal bones. We have encountered patients who have fractures of the calcaneus and talus (figure 4). In these cases, an MRI or computed tomography scan may be essential for diagnosis. We suggest consultation with a musculoskeletal radiologist to help choose the optimal study.

[FIGURE 4]

Most ankle sprains can be successfully treated with a conservative regimen of rest, ice, bracing, and functional rehabilitation. Several conditions with a worse prognosis can often be identified and treated at initial presentation. When patients continue to have pain 6 weeks or more after a sprain, a thorough examination and radiographic studies will usually allow primary care physicians to identify the cause of the chronic pain and treat it appropriately.

References

  1. McMaster PE: Treatment of ankle sprain: observations in more than five hundred cases. JAMA 1943;122(10):659-660
  2. Garrick JM: The frequency of injury, mechanism of injury, and epidemiology of ankle sprains. Am J Sports Med 1977;5(6):241-242
  3. Glick JM, Gordon RB, Nishimoto D: The prevention and treatment of ankle injuries. Am J Sports Med 1976;4(4):136-141
  4. Lassiter TE, Malone TR, Garrett WE: Injury to the lateral ligaments of the ankle. Orthop Clin North Am 120219;20(4):629-640
  5. Marder RA: Current methods for the evaluation of ankle ligament injuries. J Bone Joint Surg (Am) 1994;76(7):1103-1111
  6. Meislin RJ, Rose DJ, Parisien JS, et al: Arthroscopic treatment of synovial impingement of the ankle. Am J Sports Med 1993;21(2):186-189
  7. Ferkel RD, Fischer SP: Progress in ankle arthroscopy. Clin Orthop 120219;Mar(240):210-220
  8. Guhl JF: Ankle Arthroscopy: Pathology and Surgical Techniques. Thorofare, New Jersey, Slack Inc, 120218
  9. Loomer R, Fisher C, Lloyd-Smith R, et al: Osteochondral lesions of the talus. Am J Sports Med 1993;21(1):13-19
  10. Bassett FH, Speer FP: Longitudinal rupture of the peroneal tendons. Am J Sports Med 1993;21(3):354-357
  11. Arrowsmith SR, Fleming LL, Allman FL: Traumatic dislocations of the peroneal tendons. Am J Sports Med 120213;11(3):142-146
  12. Xenos JS, Hopkinson WJ, Mulligan ME, et al: The tibiofibular syndesmosis: evaluation of the ligamentous structures, methods of fixation, and radiographic assessment. J Bone Joint Surg (Am) 1995;77(6):847-856
  13. Hopkinson WJ, St Pierre P, Ryan JB, et al: Syndesmosis sprains of the ankle. Foot Ankle 1990;10(6):325-330
  14. Miller CD, Shelton WR, Barrett GR, et al: Deltoid and syndesmosis ligament injury of the ankle without fracture. Am J Sports Med 1995;23(6):746-750
  15. Seligson D, Gassman J, Pope M: Ankle instability: evaluation of the lateral ligaments. Am J Sports Med 120210;8(1):839-842
  16. Hamilton WG, Thompson FM, Snow SW: The modified Brostrom procedure for lateral ankle instability. Foot Ankle 1993;14(1):1-7


Initial Management of Ankle Sprains

History

Most patients who have an acute ankle injury cannot provide many details about the mechanism because the injury occurs so quickly. However, they usually describe an ankle inversion after landing awkwardly on their own foot or on an opponent's foot. They often feel or hear a snap or pop and have intense pain along the lateral side of the ankle.

They may be able to describe the mechanism of a syndesmosis injury, which occurs when the foot is planted on the ground and the inverted ankle is subjected to external rotation as the patient's upper body continues to twist internally. The ligaments can either stretch or, more rarely, completely rupture (1).

Physical Examination

When acute inversion sprains occur, patients will present with pain, typically on the lateral side of the ankle, centered around the tip of the fibula. They will also have lateral ankle swelling, ecchymosis, and pain with weight bearing. Tenderness is most common at the tip of the lateral malleolus and over the anterior talofibular ligament (ATFL). Tenderness in the area of the base of the fifth metatarsal suggests a possible fracture in that area, while tenderness over the medial side may indicate a deltoid injury. Further examination should include assessment of neurovascular function and an evaluation of ligamentous integrity.

The most commonly performed test of ligamentous integrity is the anterior drawer test (figure A). The examiner holds the distal tibia motionless and, with the patient's knee slightly flexed and the ankle in slight plantar flexion, attempts to pull the hindfoot forward. Side-to-side comparison is essential, since patients' anterior ankle laxity varies greatly. A significantly greater degree of anterior translation in the injured ankle compared with the normal side implies a rupture of the ATFL. (A translational difference of 5 mm to 10 mm is probably abnormal, but the quality of the endpoint is also important.)

Injured syndesmotic ligaments can be identified by three tests. The syndesmosis squeeze test (figure B) is done by compressing the tibia and fibula together above the level of injury. The test is considered positive if pain is referred to the anterolateral ankle in the area of the syndesmosis. The external rotation stress test (figure C) is performed by holding the talus in neutral flexion and applying an external rotation force to the hindfoot. Once again, pain in the syndesmotic area indicates injury. Finally, the tibiotalar shuck test (Cotton test, figure D) is done by applying mediolateral force to the talus. Pain in the syndesmosis or a feeling of looseness indicates syndesmotic ligament injury (the talus should not have any "slop" in the mortise; comparison with the normal side may help).

[FIGURES A and B]

Most commonly, these three tests will be negative. If they do identify a painful syndesmosis, these "high" ankle sprains will require slightly more aggressive treatment. If frank instability is evident, stress films should be obtained to rule out a complete syndesmosis rupture. This rare injury requires surgical correction.

[FIGURES C and D]

Radiography

Standard radiographs (anteroposterior, lateral, and mortise views) complete the ankle evaluation. Significant findings that would alter treatment include distal fibular fracture, osteochondral injury, syndesmosis widening, or tarsal fracture.

Treatment

Ankle sprains are typically graded as 1, 2, or 3. Though this system, in our experience, is extremely subjective and not very useful for stratifying injuries, it does provide a general classification of injury severity.

Grade 1 injuries are often insignificant, and patients rarely present for medical treatment, preferring instead to treat themselves with ice, rest, and over-the-counter analgesics. These injuries are mild enough that the only physical findings are a little tenderness and swelling. Symptomatic treatment alone is sufficient, and patients will often be over the injury and back to normal activity in 1 to 2 weeks.

Grade 2 injuries include an enormous, heterogeneous group of sprains, from the relatively mild, partial ligament ruptures with a little swelling to severe ankle sprains that preclude weight bearing. Our preferred treatment for these injuries is a functional rehabilitation program that involves rest, ice, elevation, and symptom-based limitation of weight bearing. We prefer that patients wear a functional ankle brace, such as the Aircast (Aircast Inc, Summit, New Jersey), and walk as pain allows. Within the first few days of injury, they should begin early range-of-motion and strengthening exercises and follow a home exercise program or, for the more severe injuries, a formal physical therapy program. Depending on the severity of the injury, normal activities can usually be resumed within 2 to 4 weeks of the injury.

On the far end of the spectrum are grade 3 injuries, with gross disruption of ankle stability. The talus can be easily subluxated anteriorly and posteriorly and may even be difficult to hold in its anatomic location. A reduced ankle dislocation, for instance, would be a grade 3 injury. Paradoxically, the vast amount of soft tissue damage that occurs with this injury leads most commonly to persistent stiffness rather than instability. Our preferred method of treatment for this injury is splinting or casting and crutches for several days to 2 weeks, followed by immobilization in an ankle orthosis (fracture boot), with early rehabilitation (beginning 2 to 4 weeks after injury) to maintain motion and prevent atrophy of the calf muscles (2).

Kannus and Renstrom (2) reviewed 12 prospective studies, comparing the treatment and outcome of all types of ankle sprains. They concluded that patients do just as well with the type of functional treatment described above as with casting or surgery. Over 80% of patients had a successful clinical result with this relatively simple conservative regimen. Our experience suggests that 95% or more of patients will recover with conservative treatment.

Treatment variations. Some injuries require a different treatment plan than the usual approach for a grade 2 or grade 3 sprain.

  • If a fibular fracture is detected, orthopedic consultation should be sought to determine if the fracture is stable. If it is not stable, surgical treatment is the best choice in the young, active patient.
  • Acute dislocation of the peroneal tendons indicates rupture or avulsion of the peroneal tendon sheath. In selected patients, this may be an indication for surgery.
  • When patients sustain a "high" ankle sprain (syndesmosis injury), in our experience they take two to three times longer to recover than with a typical inversion sprain. Because patients with ankle pain tend to walk on an externally rotated foot to shorten the foot's lever arm, they repeatedly and unintentionally recreate the mechanism of injury. Therefore, we prefer to put these patients in an ankle fracture orthosis with a rocker bottom, such as the Aircast pneumatic brace (Aircast Inc, Summit, New Jersey), and have them use crutches for 1 to 2 weeks. More aggressive treatment seems to shorten the course of these injuries.
  • Finally, osteochondral injuries, when seen on the initial radiograph, should also be treated with an ankle orthosis and limited weight bearing for 4 to 6 weeks. Often, these injuries will heal and become asymptomatic if recognized early.

References

  1. Xenos JS, Hopkinson WJ, Mulligan ME, et al: The tibiofibular syndesmosis: evaluation of the ligamentous structures, methods of fixation, and radiographic assessment. J Bone Joint Surg (Am) 1995;77(6):847-855
  2. Kannus P, Renstrom P: Treatment for acute tears of the lateral ligaments of the ankle: operation, cast, or early controlled mobilization. J Bone Joint Surg (Am) 1991;73(2):305-312


Dr Bassewitz is a senior resident in orthopaedic surgery and Dr Shapiro an associate professor of orthopaedic surgery at the University of California, Los Angeles, School of Medicine. Address correspondence to Matthew S. Sharpiro, MD, Dept of Orthopaedic Surgery, UCLA School of Medicine, Center for the Health Sciences, Box 956902, Los Angeles, CA 90095.


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