Percutaneous Tendo Achillis Lengthening to Promote Healing of Diabetic Plantar Foot Ulceration

Abstract

The etiology of ulcerations related to increased plantar pressure in patients with diabetes mellitus is complex but frequently includes a component of gastrocnemius soleus equinus. One viable treatment option is percutaneous tendo Achillis lengthening as a means of increasing dorsiflexory range of motion and decreasing forefoot shear forces. This article presents three case reports illustrating the importance of reducing plantar pressure as a crucial component of treatment of diabetic forefoot ulcerations.

Plantar pressure points leading to diabetic foot ulcerations have many known causes, one of which is reduced available dorsiflexion about the ankle joint. The presence of ankle joint equinus in conjunction with sensory neuropathy may increase the risk of ulceration and amputation [1-3]. It is well known that neuropathy affects the patient with diabetes mellitus in many ways. Sensory neuropathy diminishes protective sensation, leaving the individual prone to plantar stresses, and autonomic and motor neuropathies contribute to ulcer formation by reducing the integrity of the skin and altering the forces of the extrinsic and intrinsic musculature [4].

Ankle joint equinus affects the foot in several aspects of weightbearing, one of the most significant being increased and prolonged forefoot stress during ambulation [5,6]. A direct biomechanical effect of ankle joint equinus is hypermobility of the foot. In diabetic patients with neuropathy and Charcot’s arthropathy, shearing forces that cause soft-tissue deterioration and skin ulceration often occur [3,5,6]. Ankle joint equinus may also be a contributing factor in the high reulceration rate after some forefoot and midfoot amputations, such as transmetatarsal amputation [7,8] In such cases, treatment to decrease the equinus deformity may promote healing of reulceration sites in the transmetatarsal limb.

Ankle joint equinus can be addressed in several ways depending on the patient’s age, other comorbidities, and ambulation status. Treatment options are typically divided into conservative and surgical modalities. In adults, conservative care usually consists of exercise routines (stretching), orthoses, padding, and molded shoes. In younger patients, serial casting or bracing may be beneficial [9]. Other treatments include a combination of physical therapy, immobilization, orthoses (ie, a simple heel lift), and oral or injectable anti-inflammatory agents [9,10]. When these conservative measures fail, surgical intervention may be considered.

Technique

Correction of soft-tissue ankle joint equinus deformity may be addressed surgically using various methods. One of the simpler techniques is the percutaneous triple hemisection of the tendo Achillis [9]. We used this approach to treat three patients at Hines Veterans Affairs Hospital, Hines, Illinois. All three patients were placed in the prone position, and a local block was performed with or without intravenous sedation. Next, the insertion and the linear bisection of the tendo Achillis were identified. At a level approximately 2 cm proximal to the insertion, a No. 11 scalpel blade was inserted full thickness into the tendon bisection and directed medially using forced dorsiflexion of the foot, thereby transecting the medial fibers. The second incision was made approximately 4 cm proximal to the insertion and directed laterally in the same manner. The third and final incision was approximately 6 cm proximal to the insertion and directed medially. The incisions were then reapproximated using 4-0 nylon suture in simple interrupted technique. The procedure may be accompanied by thorough ulcer debridement and application of an appropriate wound-care product.

Postoperative care following percutaneous tendo Achillis lengthening consists of placement of the extremity in a compressive dressing and posterior splint to maintain the foot and ankle in a neutral or slightly dorsiflexed position. The patient is encouraged to remain nonweightbearing by using an appropriate gaitassistive device. The patients discussed here remained in a posterior splint with compression for approximately 3 to 4 weeks with local wound care. Treatment after the initial splinting depended on the appearance and healing progression of the individual ulceration. On resolution of the ulceration and after obtaining a grade 0 foot, all patients were prescribed appropriate accommodative footwear. The following case reports illustrate three different situations in which plantar ulcerations were successfully treated with percutaneous tendo Achillis lengthening.

Case Reports

Case 1

A 63-year-old man with insulin-dependent diabetes mellitus and a history of Charcot’s arthropathy, neuropathy, hypertension, and congestive heart failure presented to the outpatient podiatry clinic wearing custom-molded diabetic accommodative shoes. He had a hyperkeratotic area overlying a superficial ulceration plantar to the base of the fourth metatarsal on the right foot. Pedal pulses were nonpalpable, and the ankle-brachial index was 0.85. On initial debridement of the ulceration, it displayed a clean, granular base without malodor, discharge, or probing to deeper tissue. At this point, the ulceration measured less than 1 cm in diameter. The patient was immediately placed in an accommodative CAM Walker (Zinco Industries, Inc, Pasadena, California) for immobilization and began twice-daily antibiotic ointment dressing changes. The ulceration continued to increase in size after subsequent clinical visits for debridement, with maximum measurements of 2.2 × 2.1 × 0.8 cm occurring 3 months after initial evaluation. The base and associated tissue remained unchanged throughout, and there was no clinical or radiographic evidence of osseous involvement. At this time, surgical intervention was discussed with the patient, as conservative care was failing to decrease the ulceration size. Before surgical treatment, ankle joint range of motion was −1° of dorsiflexion with the knee joint extended and 1° of dorsiflexion with the knee joint flexed. Tendo Achillis lengthening was performed uneventfully, obtaining 10° of dorsiflexion with the knee joint extended and 12° of dorsiflexion with the knee joint flexed. Postoperative local wound care consisted of biweekly wound matrix dressings with cadexomer iodine 0.9% gel topically and below-theknee serial casting in the outpatient clinic. The patient was partially weightbearing as tolerated, using a walker for gait-assisted ambulation. Nine weeks after surgical intervention, the ulceration had resolved completely. Ten months after surgery, the ulceration remained closed and the ankle joint could dorsiflex past neutral. Ultimately, an ankle-foot orthosis with custom accommodative padding was dispensed.

Case 2

A 74-year-old man with insulin-dependent diabetes mellitus and a history of peripheral vascular disease, hypertension, and a transmetatarsal amputation after osteomyelitis 11 months earlier presented with an ulceration on the distal plantar aspect of the third and fourth metatarsals of his residual limb. The ulceration was red and granular, with no osseous involvement observed radiographically or clinically. An extensive course of local wound care with various products—including becaplermin platelet-derived growth factor gel, papain-urea fibrinolytic debriding ointment, wetto-dry dressing changes, and continuous immobilization—failed to close the ulceration site. The largest measurement during follow-up was 1.5 × 1.7 × 0.8 cm. The patient had nonpalpable pedal pulses, and the ankle-brachial index was 0.45. The patient was regularly seen by the peripheral vascular service and had previously undergone a bypass procedure. Eighteen months after initial evaluation, surgical intervention was discussed owing to the failure of conservative measures. Preoperative ankle joint range of motion measured 𢈒2° of dorsiflexion with the knee joint extended and flexed. A bony block at the ankle joint was ruled out. Percutaneous tendo Achillis lengthening was performed without incident. Postoperatively, the ankle joint displayed 8° of dorsiflexion with the knee joint flexed and extended. The patient was transitioned out of the postoperative splint at approximately 3 weeks and was placed into a cast boot with papain-urea topical debriding ointment for 6 weeks. After this phase, cadexomer iodine 0.9% gel was applied with daily dressing changes at home by the patient and his wife coupled with a surgical shoe for off-loading until ulceration resolution occurred approximately 11 months after surgery. The ulceration site has remained closed for over 16 months postoperatively, and the patient continues to obtain 5° of ankle joint dorsiflexion with the knee joint flexed and extended.

Case 3

A 68-year-old man with insulin-dependent diabetes mellitus and a history of chronic renal insufficiency, coronary artery disease, and partial left fifth-ray resection secondary to osteomyelitis was initially seen with a new ulceration plantar to the left third and fourth metatarsal heads. The ulcer initially measured 2.2 × 2.9 cm, with minimal depth. The wound was granular, superficial, and relatively clean. The patient was placed in a surgical shoe with a felt-pad accommodation, and he performed daily antibiotic dressing changes at home. Four months after initial presentation, the patient began using daily cadexomer iodine 0.9% gel dressing changes, with biweekly wound matrix bioengineered synthetic grafts administered in the outpatient clinic. He was also given a CAM Walker for continued accommodation. Six months after the initial evaluation, the ulceration persisted, with measurements of 2.0 × 2.7 × 0.1 cm, and surgical intervention was planned. Preoperative ankle joint range of motion was −8° of dorsiflexion with the knee joint extended and 0° of dorsiflexion with the knee joint flexed. Surgical percutaneous tendo Achillis lengthening was performed without complications. Postoperative ankle joint range of motion measured 6° of dorsiflexion with the knee joint extended and 8° of dorsiflexion with the knee joint flexed. Use of the cadexomer iodine topical 0.9% gel was continued beneath the compression dressing and posterior splint for approximately 3 weeks, followed by transition into a CAM Walker with continued local wound care, including periodic debridement in the outpatient clinic. On examination 7 weeks after surgery, the ulceration was completely healed. Six months after surgery, the site remained healed and the patient was walking regularly in accommodative shoes with the ability to dorsiflex the ankle to 6° with the knee joint flexed and 4° with the knee joint extended.

Discussion

The preceding case reports illustrate the effect of a tendo Achillis lengthening procedure when ankle joint equinus is a contributing factor in nonhealing plantar ulcerations secondary to increased plantar pressures. Successful treatment was accomplished by a combination of surgical tendon lengthening, diligent wound care, and off-loading. Off-loading techniques vary among practitioners. One study [11] reported that the combination of percutaneous tendo Achillis lengthening with total-contact casting resulted in faster healing of forefoot ulcerations and a decrease in ulcer recurrence.

Ankle joint equinus, as defined by Root et al [12], is less than 10° of ankle joint dorsiflexion when the knee joint is extended and the subtalar joint is maintained in its neutral position. Usually, ankle joint equinus is a direct result of adaptive shortening of the gastrocnemius muscle, spasticity, contracture, or congenital shortening. Equinus secondary to an osseous deformity of the ankle joint is suspected when ankle joint motion is restricted to less than 10° of dorsiflexion on flexion and extension of the knee joint [10,12]. Lavery et al [13] concluded that there is a high prevalence of ankle joint equinus deformity in patients with diabetes mellitus, and this deformity is directly associated with increased plantar foot pressures. In fact, they assert that the risk of developing equinus is higher in patients with a longer duration of diabetes mellitus. This was supported by Mueller et al [14], who demonstrated improved healing of plantar ulcers with Achilles lengthening in a clinical study. Palladino [10] identifies specific processes noted in patients with diabetes mellitus, including an anterior leg paresis secondary to motor neuropathy, which enables the posterior musculature to develop a mechanical advantage. Diabetic patients are also predisposed to generalized limited joint mobility, which may also be an important etiologic factor in the development of ankle joint equinus. Lavery et al [13] and Mueller et al [14] concluded that appropriate management of ankle joint equinus deformity may actually reduce the incidence of foot ulcerations and the risk of amputation. Caselli et al [15], in a multicenter prospective clinical trial, demonstrated that in neuropathic patients forefoot and rearfoot peak pressures increase with increasing levels of nerve damage but that peak forefoot–rearfoot pressure ratios are increased only in those high-ulceration-risk patients with advanced peripheral neuropathy. This further supports the argument that equinus develops in the later stages of peripheral neuropathy, thereby leading to diabetic foot ulceration. Percutaneous tendo Achillis lengthening may be effective in the resolution of plantar ulcerations and in maintaining a grade 0 diabetic foot when equinus is identified in the ulcerated foot or residual limb. Mueller et al [14] identified tendo Achillis lengthening as a tool that both assists in the healing of ulcerations and decreases the rate of recurrence by increasing ankle joint dorsiflexion and, therefore, limiting peak plantar pressures.

The literature reports minimal complications associated with percutaneous tendo Achillis lengthening procedures. Pinzur et al [7], who proposed the triple hemisection as an adjunct to midfoot amputations, reported excellent results for treatment of ankle joint equinus. Most case studies report similar results during long-term follow-up evaluation. Hastings et al [16] reported short-term deficits in peak plantar flexor torque, which were eventually compensated for by improvements in ankle joint dorsiflexion range of motion and walking ability and a decrease in forefoot inshoe peak plantar pressure. Interestingly, Piriou et al [17], in a retrospective study of 80 percutaneous tendo Achillis lengthening procedures, reported no complications related to surgical technique except for one case of calcaneal area neuropathy.

Conclusion

The three cases described above present unique scenarios of plantar diabetic ulcerations, with varying time frames and positive resolution after percutaneous tendo Achillis lengthening. Eliminating ankle joint equinus as a major biomechanical disadvantage during ambulation is beneficial to ulcer healing. These case reports identify ankle joint range of motion as a valuable measure that should be evaluated by the podiatric physician when treating plantar diabetic foot ulcerations.