It is fairly well accepted that nonoperative treatment of Achilles tendon ruptures with cast immobilization has a higher rerupture rate, but an otherwise lower complication rate, than surgical repair. It is also fairly well accepted that early postoperative weight-bearing and protected range-of-motion exercises are beneficial after surgical repair of Achilles tendon ruptures. A recent guideline and evidence report on the diagnosis and treatment of acute Achilles tendon rupture produced by the American Academy of Orthopaedic Surgeons and endorsed by the American Orthopaedic Foot and Ankle Society gave a moderate strength of recommendation for only two treatment options: (1) early postoperative protected weight-bearing (at two weeks or earlier) for patients with acute Achilles tendon rupture who have been treated operatively, and (2) the use of a protective device that allows mobilization by two to four weeks postoperatively1. On the basis of the literature that supports these recommendations and other data that also suggest that protected motion has a beneficial effect on ligament and tendon-healing in humans and animals, there has been interest in whether early protected range of motion might improve the outcomes of acute Achilles tendon ruptures treated nonoperatively.
In their excellent randomized prospective study, Willits et al. treated patients with acute Achilles ruptures either nonoperatively or with open repair. In both groups, two weeks of non-weight-bearing immobilization was followed by protected weight-bearing and motion in a walking boot with a 2-cm heel-lift. The authors noted a rerupture rate of 4.2% with nonoperative treatment and 2.8% with surgery. This difference was not significant, although the study was underpowered because of a much lower than expected rerupture rate with nonoperative treatment. With respect to other clinical findings, except for a difference in the ankle plantar flexion strength ratio between the affected and the unaffected limb at 240°/sec at one and two years postinjury in favor of the operative group and a lower side-to-side difference in ankle plantar flexion at two years postinjury in favor of the nonoperative group, there were no significant differences in outcomes, including the Leppilahti score. There was a higher rate of complications (13%), including superficial and deep infection, small openings in the skin, scar formation, and pulmonary embolus, in the operative group. These specific complications were not seen in the nonoperative group, which had an 8% rate of complications, including a primary rupture in one patient that failed to heal and was not counted as a rerupture and substantial pain in another patient. While some orthopaedic surgeons recommend the use of ultrasound or magnetic resonance imaging (MRI) to confirm that the two ends of the ruptured Achilles tendon align closely together in plantar flexion before commencing with nonoperative treatment, it is not clear if this was done in the study by Willits et al., nor is the method of measuring ankle dorsiflexion, particularly with respect to knee position, described. The authors state that the results of their study support the use of accelerated functional rehabilitation and nonoperative treatment for acute Achilles tendon ruptures.
There are at least three other prospective randomized studies in the literature in which surgical treatment of acute Achilles tendon ruptures was compared with nonoperative treatment with early functional range of motion. Thermann et al.2 noted similar results between a group of twenty-two patients who underwent surgical treatment and a group of twenty-eight patients who underwent functional treatment with a newly developed walking boot. There were no reruptures in either group. Twaddle and Poon3 treated twenty patients operatively and twenty-two patients nonoperatively with early motion controlled in a removable orthosis and noted similar clinical results including complication rates in the two groups. There were three reruptures (15.0%) in the operative group and two reruptures (9.1%) in the nonoperative group. Metz et al.4 noted a rerupture rate of 15.0% (six of forty) in patients treated with functional bracing and 4.7% (two of forty-three) in patients treated with minimally invasive surgical repair followed by taping. This difference was not significant, and there was also no significant difference between groups with regard to the mean time to return to work, non-rerupture complications, return to sports, pain, or satisfaction with treatment.
Additional studies on multiple different nonoperative functional treatment protocols for acute Achilles tendon ruptures have demonstrated rerupture rates of 5.0%5, 5.3%6, 13.0%7, 6.7%8, 2.0%9, 2.1%10, 4.5%11, and 6.4%12. Pooling the results of Willits et al. with the results of the above studies2-12 leads to an overall rerupture rate of 5.2% (thirty-six of 688) with nonoperative treatment including early functional motion for acute Achilles tendon ruptures. While this pooled rerupture rate of 5.2% is certainly lower than the 11.7% and 13% rerupture rates with nonoperative treatment consisting principally of immobilization noted in the literature review and meta-analyses by Lo et al.13 and Bhandari et al.14, respectively, it is also higher than the 2.8% and 2.5% rerupture rates noted with operative repair in those same two papers. Therefore, while functional treatment appears to be preferable to cast immobilization in patients with acute Achilles tendon ruptures treated nonoperatively, particularly in those who are compliant, there is not yet enough evidence to abandon surgical repair with open or minimally invasive techniques followed by an early protected functional range of motion and weight-bearing. However, studies such as the one by Willits et al. will help us determine which patients with acute Achilles tendon rupture might be best served by nonoperative treatment as opposed to surgery and, in such cases, by which functional rehabilitation protocol.