Only two-thirds of National Football League players ever come back, and those who do find their performance significantly affected. But research suggests a prodromal period may offer opportunities for early intervention.
by Khalid Shirzad, MD; John D. Hewitt, MD; Carter Kiesau, MD; and Selene G. Parekh, MD, MBA
Achilles tendon injuries have increased over the past few decades; however, the true frequency of Achilles tendon ruptures is unknown. These tears are usually the result of mechanical stress and intratendinous degeneration or pathology. The tendon can be affected by recurrent microtrauma with a low propensity to heal or degenerative changes within the tendon. Corticosteroids and fluoroquinolone antibiotics have also been implicated in tendon pathology.1 Mechanisms leading to tendon failure involve the rapid loading of an already tensed tendon. Proposed mechanisms of loading or overloading that result in an Achilles tendon failure include a dorsiflexion force to the ankle with a strong contraction of the triceps surae muscle, pushing off of the weight-bearing foot with the knee in extension, and a strong dorsiflexion force on the plantar flexed ankle.2 Between 75% and 85 % of ruptures have been associated with athletic activities or racquet and ball sports.1
Compared to the general population, athletes in the National Football League (NFL) are at increased risk for injury because the game involves explosive acceleration and sudden changes in direction.3 Very little is known about the epidemiology of Achilles tendon ruptures in the NFL. Utilizing data publicly available on the Internet, one retrospective review identified 31 Achilles tendon ruptures in NFL players over a five-year period (5.2 injuries/year).3 During the 2008-2009 NFL season, six players suffered season-ending Achilles tendon ruptures. Although the incidence of Achilles rupture is low, 0.93% per NFL game, nearly 36% of affected players never return to playing at the NFL level.3
Parekh et al used a player’s power rating as a measure of functional outcome in the evaluation of “skill players” in the NFL, which included defensive tackles, cornerbacks, linebackers, wide receivers, and running backs.3 The power rating is a measure of a player’s performance using statistics gathered during game play, such as passing and rushing yards for an offensive player and tackles and interceptions for a defensive player. This study showed that 31 acute Achilles tendon ruptures occurred in NFL players between 1997 and 2002. The average age of a player sustaining a rupture was 29, with an average career before injury spanning six years.
Of the 31 players who sustained an Achilles tendon rupture, 21 (64%) returned to play in the NFL at an average of 11 months after injury. In the three seasons following their return, those 21 players saw significant decreases in games played and power ratings compared to the three seasons preceding the injury.
The percentage of players returning to play at the NFL level is consistent with a meta-analysis performed by Bhandari4 in 2002. The authors reported return to function rates of 63% for patients treated nonoperatively and 71% for those treated operatively. If we assume that all the NFL players were treated operatively, as would be the standard for young athletes, the return to play rate of 64% is slightly lower than the 71% reported in the meta-analysis. This difference could be attributed to the excessive demands placed on the operatively repaired Achilles tendon in NFL players combined with a body size, strength, and explosiveness that would further increase these demands.
The length of time to allow full activity after Achilles tendon repair is generally thought to be four to six months.4-6 The 11 months needed to return to play as a professional football player seems considerably longer. However, there is a major difference between allowing full activity and returning to play in the NFL. Even when the typical patient is allowed to participate in full activity, it does not mean that he or she is adequately rehabilitated to perform at maximal efforts. Studies to determine maximal improvement after surgical treatment are lacking in the orthopedic literature.
Furthermore, in the reviewed 21 NFL skill players who returned to play, there were significant decreases in games played per season (11.67 games per year pre-injury versus 6.17 games per year postinjury) when averaged over the three seasons before the injury and the three seasons after the injury.3 There were also decreases averaging nearly 50% in power ratings of the returning players for the three seasons after the injury compared to the three seasons before the injury. These data indicate that even in players able to return to their former level of play, the quality of play may suffer permanently.
Currently, it’s thought that operative treatment yields the best functional outcome for active patients.4-12 Intra-operatively, the appropriate resting tension of the tendon should be restored. Unfortunately, this is difficult to assess because there is no objective way to predict the actual resting tension of the tendon. Theoretically, if this tension is not restored, the force-tension relationship of the muscle tendon unit is disturbed, which would lead to a decrease in functional strength in the gastroc-soleus complex. This functional weakness could lead to more subtle loss of playing ability in high-demand athletes.
Another possible factor that could have contributed to quality of play in athletes returning from Achilles tendon rupture is the rehabilitation protocol. Traditionally, patients have been treated postoperatively with a prolonged period of non-weight-bearing activity, ranging from six to eight or more weeks. More recently, studies advocating early functional activity have been published.9 These studies show improved functional outcome with respect to strength and decreased length of time to full activity. Despite having access to highly skilled rehabilitation protocols and personnel, professional football players in the U.S. may be limited in their recovery potential by an overly conservative treatment protocol.
Parekh et al3 also reported a decline in power ratings for certain skill players, specifically running backs and receivers, in the three seasons prior to their acute Achilles tendon rupture. It is possible that this observation suggests the presence of a prodromal period of Achilles tendinosis. Prodromal symptoms are reported by 15% to 20% of patients with eventual ruptures and include sharp pain in the tendon with activity, as well as reduced ankle dorsiflexion.13,14 More than half of 292 patients treated surgically for Achilles tendon rupture by Josza et al15 had evidence of preexisting degenerative changes in the tendon. Access to the NFL injury database would illuminate any symptoms these players may have been having prior to the season of their respective Achilles tendon ruptures.
The treatment of acute Achilles tendon ruptures varies, and there is no uniformly accepted algorithm of care. Management ranges from nonsurgical to percutaneous, mini-open, and formal open repair methods. In general, studies show lower re-rupture rates and better functional outcomes with surgical repair than nonsurgical management.12 Some suggest that nonsurgical management should be used only when there is coaptation of the tendon ends with the ankle in 20° of plantar flexion as verified on ultrasound or MRI. However, for athletes wishing to return to pre-injury function as quickly as possible, surgical repair is the preferred option of choice. Some have used an accelerated protocol with range-of-motion exercises 72 hours after surgery, a posterior splint for two weeks, and subsequent ambulation in a hinged orthosis. Six weeks after surgery, use of the orthosis was discontinued, full weight bearing was allowed, and progressive resistance exercises were initiated.6 This protocol is in comparison to patients with Achilles tendon ruptures treated nonoperatively, with mean casting time of 8.3 weeks prior to beginning rehabilitation.7 However, higher rates of complications do occur with surgical treatment of acute Achilles tendon ruptures.7 The most common complications from surgery include wound complications, adhesions, altered sensation, and infection. Less invasive surgical methods have been developed to minimize these complications.
Historically, re-rupture rates were higher with percutaneous and mini-open techniques compared to open repair, but recent literature suggests equal rates.11 However, coaptation of the tendon ends is not ensured with minimally invasive techniques. In addition, MRI findings show that it takes longer for the tendon gap to disappear with percutaneous methods (11.6 weeks) than with open repair (8.6 weeks).8 Some surgeons use endoscopy in addition to their minimally invasive technique to confirm that the tendon ends are approximated.10 Studies comparing percutaneous repair to open repair show no difference in re-rupture rates, but the infection rate is higher with open repair.5
Rehabilitation after surgical repair is trending over the past decade toward earlier motion and weight bearing. This trend is somewhat based on knowledge of improved strength and gliding of tendon repairs following hand surgery after rehabilitation protocols with early motion and controlled loading. Such ideas of early motion have also been popularized in anterior cruciate ligament reconstructions. In a retrospective review, Shelbourne16 showed a reduction in loss of knee motion and strength after an accelerated rehabilitation program following ACL reconstructive surgery; however, in a more recent prospective randomized analysis, Beynnon et al17 showed no difference in functional performance between the study’s two groups.
A goal of surgical Achilles treatment is to prevent tendon elongation, which can be responsible for decreased power of the gastroc-soleus complex, by lengthening the musculotendinous unit. Patients with a surgically repaired Achilles tendon, who are placed in a brace and allowed early motion from neutral to plantar flexion, have less tendon elongation than do patients who are treated in a cast.18 Studies looking at immediate weight bearing have shown an earlier time to normal walking and stair climbing, but not in return to sports.19 Suchak et al20 noted an improvement in outcome scores, enhanced quality of life, and activity level in the early postoperative period with a weight bearing as tolerated protocol; however, no difference was found at six months. Studies have also shown that formation of adhesions and sural nerve deficits were less frequent with use of functional rehabilitation versus immobilization postoperatively.21,22 One concern in an early motion and weight-bearing protocol is the potential for increased risk of re-rupture if patients prematurely return to strenuous activity. Other authors have shown no significant differences between patients treated with early functional treatment and those with immobilization with regard to pain, stiffness, subjective calf muscle weakness, footwear restrictions, range of ankle motion, calf muscle strength, or overall outcome.21,23
The decrease in power ratings seen in the NFL players could suggest that they are returning too soon, before rehabilitation is fully complete, that the ultimate strength of the healed repair is less than its pre-injured state, or that the musculotendinous unit may have lengthened. Based on the literature, the best treatment for athletes would consist of surgical repair, with an open, mini-open, or percutaneous technique, focused on tendon apposition and proper musculotendinous unit tensioning followed by a functional rehabilitation program involving a progression of increasing motion, weight-bearing, and strengthening exercises. Typically, return to sports is allowed at six months. Even after return to activity, it may be necessary for patients to perform more intense strength training of the repaired tendon and gastroc-soleus complex prior to full participation in their sport.
Acute Achilles tendon rupture can be a career-ending injury for athletes. The question arises as to whether we should be more aggressive in treating a prodromal period in an attempt to avoid a subsequent rupture. This treatment would be initiated by pain and symptoms experienced by the athlete. Initial evaluation should consist of taking a history and performing an exam. Ultrasound evaluation or MRI may be considered to evaluate the presence of tendinopathy. If tendinopathy is not present and a prodromal period is suspected, then initial treatment should consist of activity modification, nonsteroidal anti-inflammatory drugs (NSAIDs), a heel lift, and physical therapy concentrating on eccentric strengthening of the gastroc-soleus complex. While some stretching may be beneficial, aggressive stretching may aggravate the symptoms. Further treatment could include vasodilation with topical nitric oxide, which has been shown to reduce pain and improve outcomes in cases of chronic tendinopathy.24,25 Other investigational treatments include pulsed electromagnetic fields and extracorporeal shock-wave therapy. If tendinosis is present, the treatment would be the same; however, further surgical options would include percutaneous longitudinal tenotomy and open debridement.
Achilles tendon ruptures can have dramatic career implications for the athlete. These are complex injuries, with surgical intervention being only the first step in the recovery. The ultimate return to function is based on a variety of variables, some of which are controllable by the surgeon, athlete, and therapists. Ultimately, more research will be needed to examine these injuries and their outcomes to determine the ideal protocols for treatment of the competitive athlete.
Khalid Shirzad, MD; John D. Hewitt, MD; and Carter Kiesau, MD, are fellows of foot and ankle surgery in the division of orthopaedic surgery at Duke University in Durham, NC. Selene G. Parekh, MD, MBA, is an associate professor of surgery in the same division.
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