➢ On physical examination, the Thompson test is the most sensitive evaluation for diagnosing acute Achilles tendon ruptures; palpation of a gap is less sensitive. A heightened level of suspicion for this injury is necessary for patients older than fifty-five years of age, obese patients, and those injured during non-sports activities.
➢ Functional rehabilitation protocols have decreased the rerupture rate historically seen with nonoperative management of acute Achilles ruptures. Operative treatment may provide some functional benefits, but recent studies suggest that many of these benefits are transient or subtle.
➢ The role of tendon gaps that persist despite ankle plantar flexion, and the impact of such gaps on clinical outcomes, remain unclear.
➢ The rate of deep vein thrombosis after Achilles tendon rupture may be higher than that observed in many other foot and ankle conditions, but the majority of thrombotic events are unlikely to be clinically important. An age greater than forty years and an inability to mobilize may increase the risk of deep vein thrombosis.
There is controversy regarding the appropriate treatment of acute Achilles tendon ruptures, underscored in a recent clinical practice guideline published by the American Academy of Orthopaedic Surgeons, in which twelve of sixteen recommendations were supported by “weak” or “inconclusive” evidence1. The basis of debate has shifted, however, as new functional rehabilitation protocols have altered the risk-benefit analysis inherent to decisions about whether to provide operative or nonoperative management2,3. In this review article, we highlight the expanding role of nonoperative management and delve into its effects on rerupture rates and functional outcomes. In patients opting for operative repair, minimally invasive techniques may assuage some operative risks. We also underscore a potentially heightened risk of thromboembolic events among at-risk populations.
The overall incidence of Achilles tendon rupture has increased in recent decades, and some studies have shown a bimodal sex distribution, with the rate peaking in men at thirty to forty years of age and in women at sixty to eighty years of age4,5. Sports activities predominate as the cause of injury among younger populations whereas activities of daily living predominate in older populations6. Men predominate in most epidemiologic series of Achilles tendon ruptures, but this over-representation diminishes substantially in populations in which women heavily participate in ball sports7. Causal agents such as fluoroquinolone use or steroid injection may increase the risk of rupture, but they represent small contributors to the overall incidence8,9.
The diagnosis of an acute Achilles tendon rupture is generally based on patient history and physical examination. The use of imaging modalities such as ultrasound or magnetic resonance imaging (MRI) is generally not indicated unless physical findings are equivocal10. Patients often describe the sudden onset of pain that feels as if they had been kicked in the back of the ankle, at times with an audible snap, although history alone can be deceptive11. One study showed that, among physical examinations for Achilles tendon rupture, the calf squeeze test (i.e., the Thompson test) has the highest sensitivity (0.96) whereas palpation of a gap has the lowest (0.73)12. In some patients, edema may obliterate any appreciable gap. Furthermore, the posteromedial flexor tendons may permit substantial plantar-flexion force despite a nonfunctioning Achilles tendon. Ankle dorsiflexion may also be increased on the ruptured side as compared with that on the uninjured side13. Delay in diagnosis is more common for patients older than fifty-five years of age, those with a body mass index (BMI) of >30 kg/m2, and those injured in non-sports activities. Therefore, a heightened level of suspicion is requisite for these subgroups12.
Initial management generally entails splinting in plantar flexion. A cadaveric study of Achilles tendon ruptures showed that, while there was an Achilles tendon gap of approximately 20 mm with the ankle at neutral, tendon apposition occurred with maximum plantar flexion14. In vivo studies with ultrasound demonstrated that an average gap of 12 mm with the ankle in neutral decreased to 5 mm with the ankle in maximum equinus; increasing knee flexion from 0° to 90° progressively decreased this gap further to 2 mm, but this additional gain is unlikely to be clinically important or practical from a patient’s point of view15. In one prospective study of 125 patients who presented with an acute Achilles tendon tear, the authors utilized ultrasound to measure the tendon gap distance with the ankle in “as much plantar flexion as pain allowed.”16 Fifty-eight patients had a gap of <5 mm and were treated nonoperatively, whereas sixty-seven had a gap of ≥5 mm and underwent operative repair. The rehabilitation protocol included active ankle range-of-motion exercises commencing at three weeks in both groups. The authors found no statistical difference in the rerupture rates. Notably, they did not specify why 5 mm of tendon gapping was used as the cutoff point for surgery or elucidate whether larger gaps can effectively be treated nonoperatively. Thus, while one may intuit that the degree of tendon gapping with the ankle in plantar flexion should play a role in treatment algorithms, its actual clinical importance remains unclear.
Studies examining tendon repair underscore that the mechanical properties of healing tendons depend on a delicate balance between loading and unloading17. Patients treated with tendon repair at the tendon-bone interface, such as rotator cuff repair, may uniquely benefit from a period of complete immobilization18,19. In contrast, complete unloading of midsubstance repairs is generally detrimental, leading to less vigorous healing and to tendon adhesions that prevent excursion20,21. Rat models of Achilles tendon ruptures have demonstrated that complete immobilization decreases both the callus size and the mechanical strength of healing tendon, while some degree of loading stimulates healing22,23. Human roentgen stereophotogrammetric analysis (RSA) confirmed that controlled tensional loading of Achilles tendon repairs leads to a higher tendon elastic modulus, suggesting that early motion may improve functional outcomes via its direct effects on the mechanical properties of the healing tendon rather than its nonspecific impact on soft-tissue swelling or joint stiffness24. Overloading, however, may lead to gap formation at flexor tendon repair sites, and this balance must be considered in any rehabilitation protocol25.
Operative Versus Nonoperative Management
Historically, the decision to treat an acute Achilles tendon rupture operatively or nonoperatively involved a trade-off between wound complication rates and the risk of rerupture. A meta-analysis that pooled the outcomes of six randomized and quasi-randomized trials revealed an infection rate of 4.7% (range, 4% to 20%) among patients treated operatively but also a concomitant lower rerupture rate (3.1% versus 13%)26. Rehabilitation protocols, however, were not uniform across cohorts; for example, in one of the included studies the postoperative protocol was cast immobilization for eight weeks in the nonoperative group but early motion in the operative group27. Six to eight weeks of cast immobilization was used in the remaining five studies3. A subsequent meta-analysis that similarly pooled twelve studies comparing operative and nonoperative intervention confirmed this inherent trade-off between rerupture rates (3.5% versus 12.6%) and infection rates (4% versus 0%)28.
More recently, studies have underscored the critical role of functional rehabilitation protocols in determining outcomes, especially among nonoperatively treated patients. In one study, 144 patients were randomized to operative or nonoperative treatment but, crucially, all patients followed an accelerated rehabilitation protocol that incorporated early weight-bearing and range of motion3. The infection rate was 7% (five of seventy-two), with one deep infection, and the wound dehiscence rate was 3% (two of seventy-two) among operatively treated patients, but the rerupture rate was similar over two years regardless of whether operative or nonoperative treatment had been performed (3% and 4%). In an additional patient in the nonoperative group (1%), the rupture failed to heal. A subsequent meta-analysis that specifically distinguished between studies that incorporated an early range of motion and those that did not revealed that, with functional rehabilitation, the rerupture rate was equal between patients treated operatively and those treated nonoperatively29. The wound complication rate, as expected, was higher among those treated operatively. Of note, a separate meta-analysis did show a higher rerupture rate with nonoperative management, but the authors failed to perform a stratified subgroup analysis of the pooled data30. They therefore did not distinguish between studies in which functional rehabilitation had been used and those in which the patients had been treated with prolonged immobilization31.
In light of recent findings, the debate about operative versus nonoperative intervention has shifted from a focus on rerupture and infection rates to a focus on functional outcomes. One of the aforementioned meta-analyses showed no significant difference in “return to normal function” between patients treated operatively and those treated nonoperatively (p = 0.68), although normal function was not clearly defined26. Accordingly, more recent studies have incorporated specific tasks or outcome measures. Another of the aforementioned meta-analyses demonstrated no difference in range of motion, calf circumference, or strength between operative and nonoperative patient groups or showed a difference in results according to functional outcome scales29. The authors did note, however, that patients who were treated operatively returned to work almost three weeks earlier, underscoring that any treatment strategy incurs not only direct costs of care but also indirect costs such as lost patient income. Individual studies have highlighted potential functional benefits to operative management, although some of these benefits are subtle or disappear with time. One study, based on questionnaires, showed that patients treated operatively were better able to perform single heel rises at an average of 3.6 years after operative treatment32. Another study revealed that peak plantar-flexion torque was significantly better at three months among patients treated operatively than among those treated nonoperatively (61% versus 47% of the torque on the uninjured side, p < 0.005), but this benefit disappeared by six months33. In yet another study, operatively treated patients demonstrated improved functional outcome—in terms of hopping ability or performance during a drop countermovement jump maneuver (a one-footed drop from a 20-cm height followed by another jump)—at one year34. This same study, however, demonstrated that surgery provided no functional benefits in terms of concentric power, eccentric power, heel-rise repetitions, heel-rise height, or heel-rise work.
In summary, current studies suggest that functional rehabilitation protocols, when used in lieu of cast immobilization, have to a certain extent mitigated the higher rerupture rates historically associated with nonoperative management of acute Achilles tendon tears. Moreover, they do so without the wound complication rates inherent to operative repair. Operative repair may provide functional benefits, but studies suggest that these benefits may be transient or incremental and perhaps limited to the higher reaches of athletic endeavors. Additional research with well-designed, randomized clinical trials is necessary to clarify the potential for incremental functional gain with operative repair as well as whether nonoperative treatment is more likely to fail in certain patient subgroups.
Open Versus Minimally Invasive Procedures
The wound complication rates encountered with open repair spurred the development of minimally invasive techniques35. A percutaneous technique using stab wounds along the tendon border was originally described by Ma and Griffith and subsequently modified to improve repair strength36,37. Nonetheless, such a percutaneous technique places the sural nerve at increased risk of injury via suture entrapment, with injury rates as high as 17% in one study (eight of forty-eight patients)38. More recent limited open techniques therefore utilize a short, midline longitudinal incision that allows one to pull the sutures from a transcutaneous location to a sub-paratenon location, decreasing the incidence of sural nerve injury39,40. In one study, such a technique was used in eighty-seven patients with no associated sural nerve injuries41. Subsequent studies have confirmed a low rate of sural nerve injury, with the added benefit of improved wound complication rates42. In a recent systematic review comparing open and minimally invasive repairs, deep infection was found in 2.4% (nine) of 375 patients who underwent open repair as opposed to no deep infections in 406 patients treated with minimally invasive techniques43. Wound necrosis rates were also higher among patients treated with open repair (4.5% versus 0.3%).
Importantly, minimally invasive techniques appear to provide functional outcomes equivalent to those obtained with open repair. Studies directly comparing the two surgical approaches showed similar American Orthopaedic Foot & Ankle Society hindfoot clinical outcome scores and no difference in clinical parameters such as range of motion, calf circumference, plantar flexion strength, and ability to perform single toe rises39,42,44,45. Minimally invasive repairs, however, may be more difficult to perform when tendon edges are frayed, in which case the longitudinal incision used in the limited open technique can be converted to a standard open repair46.
Augmentations of acute Achilles tendon repair, be it with techniques such as fascial turndowns or plantaris tendon weaves, have not been shown to improve clinical outcomes over those provided by end-to-end repair39,47,48. In fact, augmentation may actually have deleterious effects, including prolonged operative times, longer incisions, increased local scar tenderness, and more prominent tendon thickness at the repair site.
Deep Vein Thrombosis and Pulmonary Embolism
Controversy remains regarding the rate of thrombotic events after acute Achilles tendon tears, with reported prevalences ranging between 0.4% and 34%, all in studies in which prophylactic anticoagulation was not routinely prescribed49. Partly at issue is that some studies identified deep vein thromboses with routine screening ultrasonography in all patients whereas, in others, ultrasonography was performed only when patients became clinically symptomatic. One prospective study in which 100 patients with an acute Achilles tendon tear were screened with ultrasonography, regardless of whether they were clinically symptomatic, demonstrated a deep vein thrombosis rate of 34% with no difference between patients treated operatively and those treated nonoperatively50. In contrast, a retrospective study demonstrated a 6.3% rate of clinically symptomatic venous thromboembolism among 208 patients, including 1.4% who sustained a pulmonary embolism51. The majority of these patients (83.2%) were treated nonoperatively, and routine care of both operative and nonoperative patients included six to eight weeks of cast immobilization. A similar rate of clinically symptomatic deep vein thrombosis (4%) was found in a consecutive series of 100 patients who underwent operative repair and were treated with cast immobilization for six weeks postoperatively52. Yet another study showed a 5.7% rate of symptomatic deep vein thrombosis and a 1.1% rate of pulmonary embolism among eighty-eight patients treated operatively and whose postoperative protocol entailed four weeks of cast immobilization followed by functional bracing53. More recently, however, a large retrospective study of 1172 patients who presented to a large hospital system with an acute Achilles rupture revealed rates of clinically symptomatic deep vein thrombosis and pulmonary embolism of 0.43% and 0.34%, respectively49. There was no reported correlation between venous thromboembolism rates and risk factors such as age, obesity, or a history of thrombotic events. The authors of that study noted only that patients were mobilized on crutches postinjury. Closer examination of the data reveals that none of the deep vein thromboses occurred in patients younger than forty years of age, and that the p value for the difference in deep venous thrombosis rates between patients who were less than forty years old and those who were forty or older approached significance (p = 0.068). To further complicate matters, in contrast to the low rates of deep vein thrombosis found in other retrospective studies, a recent study showed a symptomatic deep vein thrombosis rate of 23.5% among 115 patients treated operatively54. Interestingly, while all patients in that study underwent four to six weeks of immobilization postoperatively, one-third of the deep vein thromboses occurred preoperatively, and an age greater than forty was a significant risk factor for deep vein thrombosis.
Taken together, the incidence of deep vein thrombosis in patients with acute Achilles tears is possibly as high as one in three, but the vast majority of deep vein thromboses are asymptomatic and unlikely to be clinically relevant. While the largest series suggest that symptomatic deep vein thrombosis rates are comparable with those associated with other foot and ankle injuries, multiple smaller series do raise some concern, especially about patients older than forty years of age and those unable to mobilize49-54. In addition, many deep vein thromboses after Achilles tendon rupture occur preoperatively, a finding buttressed by studies showing that below-the-knee immobilization of lower-limb injuries is associated with deep vein thrombosis rates ranging from 4% to 19%55-57. Thus, prophylactic anticoagulation should be considered for older patients with an Achilles tendon rupture, including those treated nonsurgically, as well as for patients with other known risk factors. Those who purport high rates of deep vein thrombosis may underscore the importance of the soleus muscle in facilitating venous return from the lower extremity57.
Functional rehabilitation protocols have mitigated the historically higher rerupture rate associated with nonoperative management of acute Achilles tears without the operative risk of wound complications. Operative repair may provide functional benefits, but some of these benefits are subtle or transient (Table I). Questions remain about the role of tendon gaps that persist despite maximum ankle plantar flexion when Achilles ruptures have been treated nonoperatively. The rate of deep vein thrombosis after Achilles tendon rupture may be higher than that associated with other foot and ankle conditions, but the majority of deep vein thromboses are unlikely to be clinically relevant.
Source of Funding: No external funds were received in support of this study.
Investigation performed at the Brigham Foot and Ankle Center, Department of Orthopaedic Surgery, Brigham and Women’s Faulkner Hospital, Boston, Massachusetts
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
- Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated