Tendo-Achilles Lengthening: Friend Or Foe In The Diabetic Foot?
The TAL is a popular choice for the lengthening of the Achilles tendon and surgeons have utilized this procedure for the reduction of an equinus deformity for decades.4,30-33 A commonly utilized technique involves triple hemi-sectioning of the Achilles tendon through a percutaneous approach, thereby lengthening both the soleus and gastrocnemius components of the Achilles tendon. Researchers have reported that for each centimeter of lengthening, there is 3 to 12 degrees of increased ankle joint dorsiflexion.34,35 The simplicity of this approach makes this a popular choice.
Does TAL Have Adjunctive Benefits For Chronic, Diabetic Ulcers?
Surgeons have effectively used TAL as an adjunctive procedure for the treatment of chronic nonhealing ulcerations in patients with diabetes. Theoretically, the TAL should decrease the forces on the plantar aspect of the foot. Armstrong, et al., demonstrated this by reporting a significant decrease in forefoot pressures at eight weeks after performing a TAL.36 Various researchers have reported that the healing rate for chronic diabetic ulcerations after a TAL is greater than 90 percent with a low reported risk of recurrence.36-39
Mueller, et al., conducted the most robust study in examining the efficacy of a TAL for the healing of chronic diabetic ulcerations.40 This was a prospective, randomized trial that compared a TAL plus total contact casting (TCC) versus TCC alone. They reported a significant decrease in the rate of recurrence and an increase in the time for recurrence in the TAL group.
Based on the aforementioned evidence and other reported trials, the TAL appears to be an effective adjunctive procedure in healing chronic diabetic ulcerations. The perception is that one should perform TALs routinely as an adjunctive procedure. However, as we explore the literature, it becomes evident that one must conduct a more careful evaluation before performing a TAL.
Potential Complications With TAL: What You Should Know
As I noted previously, the purpose of the TAL is to increase the range of motion at the ankle joint by lengthening the Achilles tendon. A potential complication from this lengthening is overlengthening. Heel ulcerations are a consequence of this overlengthening with reported rates of 13 to 14 percent.39,40 Accordingly, we run the risk of replacing one chronic ulcer with a potentially more devastating problem.
An important addendum to this issue is raised by a study published by Shaw, et al.41 They prospectively evaluated the peak forces experienced in the foot during gait. They examined 181 patients including healthy controls, patients with diabetes, patients with diabetic neuropathy, diabetic neuropathic patients with a history of ulcerations, and patients with Charcot neuropathy. The study authors reported that all diabetic groups displayed increased peak vertical forces in comparison with the healthy controls.
However, these peak vertical forces occurred during heel strike and not at push off in the neuropathic diabetic group. This challenges the notion that patients with diabetic neuropathy are at high risk of ulceration due to increased forces in the plantar forefoot during gait. Furthermore, patients who undergo a TAL may be at an even higher risk of plantar heel ulcerations. Accordingly, the surgeon must conduct careful evaluation of the foot type and structure, including a thorough gait analysis, prior to performing a TAL.
Another potential complication of a TAL is Achilles tendon ruptures. Achilles tendon ruptures reportedly occur 10 percent of the time.39 The percutaneous approach to a TAL is essentially a blind procedure. Therefore, regardless of the deliberation by the surgeon, it is possible to compromise the Achilles tendon completely. Further, due to poor patient education or patient noncompliance, the surgically incised Achilles tendon is at risk for a complete rupture. This will significantly alter gait patterns and potentially cause new ulceration production in the area of the heel or contralateral limb.