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AAOS Now

Published 4/1/2012
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Terry Stanton

NFL Study Sheds Light on Syndesmotic Sprains

Not all require complex treatment or involve long recovery

A study of ankle sprains sustained by National Football League (NFL) players suggests that aggressive nonsurgical treatment is advisable for syndesmotic sprains. Although these injuries may require longer rehabilitation periods than lateral ankle sprains, the study reports that time away from play may not be as prolonged as previously reported in professional football players.

The results of the study—a database review of injuries on a single NFL team along with a survey of team physicians—were presented by Daryl C. Osbahr, MD, at the 2012 American Orthopaedic Foot & Ankle Society Specialty Day.

Compared with more common lateral ligamentous ankle injuries, “more severe injury patterns and variable treatment regimens have made outcomes after syndesmosis injuries more unpredictable and more likely to delay an athlete’s return to play,” Dr. Osbahr said. Although several studies address diagnostic and recovery factors for these sprains—which account for 18 percent of all NFL ankle sprains—“there is a paucity of published data comparing and evaluating outcomes of these injuries in professional football players,” Dr. Osbahr said.

With this study, he and his colleagues sought to quantify the incidence, type, management, and outcome of injury in a single team. Based on the survey results, they also evaluated diagnostic and treatment algorithms for syndesmotic and lateral ankle sprains among all 32 NFL team physicians.

One team’s story
In the first phase, the injury database of a single team was reviewed for syndesmotic and lateral ankle sprains during a 15-year period. All injuries were prospectively entered by the team’s athletic trainer after consultation with the head orthopaedic team physician. The following injury and diagnostic measures were then analyzed:

  • player position
  • foot and ankle protective gear (none, tape, brace, or unknown)
  • playing surface
  • field condition (normal, wet, hard, or unknown)
  • place of injury (game or practice)
  • time of injury in the game or practice
  • type of play (collision, tackled, tackling, blocked, blocking, running/cutting, kicking, or unknown)
  • mechanism of injury (direct impact, torsion, shearing, or unknown)

Syndesmotic and lateral ankle sprains were classified according to standard clinical classification guidelines. Syndesmosis sprains were classified in a similar manner with the West Point Ankle Grading System, while lateral ankle sprains were classified according to clinical symptoms (Table 1).

Researchers identified 36 syndesmotic and 53 lateral ankle sprains during the study period. All players in both groups were managed nonsurgically.

The syndesmosis group included 20 grade 2 and 16 grade 1 injuries; the lateral ankle sprain group included 30 grade 1, 21 grade 2, and 2 grade 3 injuries. There was a statistically significant difference in time away from play between the syndesmosis (15.4 +/– 11.1 days) and lateral ankle (6.5 +/– 6.5 days) sprain groups (P < 0.001). Two players with syndesmosis sprains and four players with lateral ankle sprains had recurrent injuries.

League-wide results
The surveys were completed by physicians from all 32 NFL teams. When managing syndesmosis sprains with no diastasis, most team physicians used immobilization, which ranged from a CAM walker to casting; however, two physicians used only ankle taping or an elastic-fabric bandage.

Physicians also had different strategies on initial weight-bearing status; 14 permitted weight bearing as tolerated, 12 allowed partial weight bearing, and 6 forbade initial weight bearing. Most physicians said they ideally progressed players to full weight bearing by 2 weeks (94 percent).

In managing syndesmosis sprains with latent diastasis, team physicians used radiographs and MRI to direct treatment algorithms. Three out of four (78 percent) relied on increased tibiofibular clear space on a stress mortise view as an indicator of the need for an operation. Other radiographic indicators included increased tibiofibular clear space on the stress anteroposterior view, increased tibiofibular clear space on the weight-bearing anteroposterior view, and increased fibular migration on the stress lateral view.

On MRIs, complete tears of the anteroinferior and posteroinferior tibiofibular ligaments as well as an interosseous ligament tear greater than 10 cm up the leg were the most important predictive factors indicating the need for surgery. MRIs can also show the following indicators for surgery: interosseous membrane tears, interosseous ligament tears less than 10 cm up the leg, and isolated posteroinferior tibiofibular ligament tears.

Injury severity, based on presence of syndesmotic diastasis, was an important factor in return-to-play guidelines. Almost all of the physicians estimated that time lost from participation after a syndesmotic sprain with no diastasis is 1 to 8 weeks; most estimated return to play at between 1 and 4 weeks. In addition, most (81 percent) of the physicians estimated that time lost from participation after a syndesmotic sprain with latent diastasis is 5 to 12 weeks.

Syndesmotic sprains associated with frank diastasis, however, had the most prolonged course for return to play. In these situations, all team physicians said that surgical management is warranted, and the reported time away from play ranges from 9 to 16 weeks. Three out of four physicians preferred applying fixation across four cortices, using two nonabsorbable syndesmosis screws.

Conclusions
Dr. Osbahr said the findings indicate that recovery from milder syndesmotic sprains may sometimes be faster than previously thought. “Although syndesmosis injuries may be more debilitating than lateral ankle sprains, our study also demonstrated that, in a certain cohort of athletes with very mild injuries, a return-to-play after syndesmosis sprain may be quite rapid (around 2 weeks),” he said. “In addition, our study found that only brief periods of immobilization and protected weight bearing may be necessary with some of these more mild syndesmosis injury patterns.”

Dr. Osbahr concluded that stable injuries involving the lateral ankle complex and syndesmosis—comprising 95 percent of all ligament strains—can generally be managed effectively with a conservative approach, typically involving progressive weight bearing and a functional rehabilitation program. These patients may be able to return to play within a couple of weeks.

However, Dr. Osbahr also stresses that one must be especially critical when evaluating treatment options and outcomes for syndesmosis injuries with latent or frank diastasis. He said that “we still need future research studies to evaluate the long-term implications of these syndemosis injuries with latent diastasis, for which the long-term prognosis of operative and nonoperative treatment is largely unknown.”

“When there is evidence of a more severe syndemosis injury, including tibiofibular diastasis,” he continued, “surgical intervention will typically be necessary to allow for successful return to play, prevent functional disability, and minimize the potential for early-onset osteoarthritis. Although this subset of severe syndemosis injury is rare in this cohort of athletes, the physician should critically evaluate the injury pattern to allow proper treatment and optimize return to play.”

Coauthors with Dr. Osbahr (no conflicts reported) were Mark C. Drakos, MD (no conflicts); Padhraig F. O’Loughlin, MD (no data); Stephen Lyman, PhD (American Journal of Orthopedics; International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine); Ronnie P. Barnes, MA, ATC (no conflicts); John G. Kennedy, MD (no conflicts); and Russell F. Warren, MD (Biomet, Smith & Nephew, Cayenne, Orthonet, ReGen Biologics, Wolters Kluwer Health/Lippincott Williams & Wilkins).

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

  • Most NFL physicians manage syndesmotic sprains with no diastasis conservatively, using immobilization—generally with a boot—although all agree that a sprain associated with frank diastasis requires surgical repair.
  • Stress radiographs and MRIs can be used to identify candidates for surgery, based on tibiofibular clear space (radiographs) and ligament tears (MRIs).
  • Return to play for patients with mild syndesmotic sprains can be sooner than generally perceived.