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A Closer Look At Tendon Lengthening In Patients With Ankle Equinus

How can surgeons choose the most effective tendon lengthening procedure for patients with ankle equinus? These authors provide a detailed guide to various permutations of tendo-Achilles lengthening and gastrocnemius recession procedures, citing the advantages and disadvantages of each technique.

Ankle equinus is associated with a wide variety of foot and ankle conditions, and surgical treatment is common in conjunction with other treatments.

Physicians have historically used the Silfverskiold test to differentiate between gastrocnemius equinus and combined gastrocnemius-soleus equinus, which has implications for procedure selection.1 A positive Silfverskiold sign indicates ankle equinus that is present when the knee is extended but disappears when the knee is flexed, which indicates gastrocnemius equinus. Combined gastrocnemius-soleus equinus does not improve with flexion of the knee. Additional clinical signs of ankle equinus include genu recurvatum, hip flexion, lumbar hyperlordosis and forefoot overload.

DiGiovanni and colleagues further defined equinus as ankle joint dorsiflexion of less than 5 degrees with the knee extended for gastrocnemius equinus and dorsiflexion of less than 10 degrees with the knee flexed for gastrocnemius-soleus equinus.2 These clear definitions have led to consistency among clinicians for evaluating and diagnosing equinus. However, surgical procedure selection guidelines are not as well defined.  

Indications for surgical lengthening in patients with ankle equinus include equinus with or without an associated lower extremity disorder that has not responded to conservative care.3 Surgeons typically correct ankle equinus with an adjunctive procedure, which has implications regarding patient positioning and postoperative ambulatory status.

Initially, the surgeon must decide between tendo-Achilles lengthening and gastrocnemius recession.3 Surgeons can perform a tendo-Achilles lengthening with an open “Z” lengthening, a minimally invasive triple hemi-section approach or a percutaneous complete tenotomy. In regard to the gastroc recession, there are generally five choices: proximal gastroc recession (Silfverskiold), deep gastroc recession (Baumann), distal gastroc recession (Strayer), endoscopic gastroc recession and superficial gastroc recession (Baker).

Procedure selection beyond tendo-Achilles lengthening versus gastroc recession is frequently based more on surgeon familiarity with a few favorite techniques more so than established patient-centered guidelines. We believe there is an opportunity to approach procedure selection based on factors specific to the individual patient and planned adjunctive procedures.

Procedure Selection Considerations For Gastrocnemius Recession

Our patient-centered ankle equinus procedure selection protocol is based on multiple factors including patient age, desired activity level, underlying medical conditions like neuropathy or neuromuscular disorders, adjunctive procedures and risk profile of the various surgical techniques. This approach individualizes procedure selection to optimize operating time related to patient positioning, avoids excessive tendon lengthening, minimizes scar visibility, and minimizes the risk of side effects like sural neuritis.

We present the following scenarios to highlight procedure selection considerations within the tendo-Achilles lengthening and gastrocnemius recession categories. We acknowledge there is always more than one correct procedure for a given patient and this approach is intended to raise awareness of factors that are worthy of consideration.

Key Insights On Intramuscular Aponeurotic Recession

The Baumann procedure, first described by Baumann and Koch, is very conducive to performing on patients in the supine position with a 3 to 5 cm incision at the medial midsubstance of the gastrocnemius muscle belly.4 Natural external rotation of the leg provides good visibility when performing supine procedures like flatfoot reconstruction.5 The medial incision provides a less visible scar high on the inside of the calf, which patients may prefer if they would like to avoid a visible scar on the back of the calf (see photo 1).

The proximal location of this procedure makes it a true gastrocnemius-only lengthening, which is less aggressive.4,5 This conservative lengthening may not be enough for some conditions but benefits of the procedure include optimal preservation of muscle mass and strength, which is important for pediatric and athletic patients.5 There is a low risk of sural nerve injury based on the high medial incision and deep intra-muscular dissection but there is some risk to the saphenous nerve given this location.5 Patients tolerate immediate postoperative weightbearing since gastroc aponeurotic recession has a minimal risk of overlengthening.  

Ideal patient selection for this procedure includes: athletes with persistent insertional Achilles tendonitis, plantar fasciitis or metatarsalgia associated with gastrocnemius equinus; patients who are undergoing pediatric flatfoot surgery; and adults with posterior tibial tendon dysfunction who have mild equinus, or are concerned about cosmesis/scar visibility.

Pros. The Baumann procedure is a true gastrocnemius lengthening with a low chance of overlengthening. It is sural nerve friendly, preserves calf muscle definition and leaves a less visible medial scar.

Cons. The wide area of muscle adds the challenge of full medial to lateral access and finding the proper location of the incision is important for exposure. The Baumann procedure is a less aggressive lengthening.

What You Should Know About The Distal Gastroc Recession

The Strayer gastroc recession is the workhorse of equinus surgery for many surgeons since it is highly conducive to supine surgery, provides adequate lengthening and is relatively friendly to the sural nerve provided the surgical exposure is deep to the peritenon level.6 It is possible to perform a gastrocnemius-only Strayer lengthening but only if exposure is above the conjoined tendon just below the gastrocnemius muscle belly.6

Photo 2 demonstrates an example of incision placement and intraoperative visualization. Immediate weightbearing in a below-knee fracture boot is generally tolerable and often desirable depending on adjunctive procedures.

Ideal candidates for a Strayer gastroc recession include patients who are having multiple procedures that require supine positioning, such as flatfoot reconstruction or total ankle replacement.6,7 An advantage of distal gastroc recession over tendo-Achilles lengthening in conjunction with a total ankle replacement is that the Strayer procedure allows for early weightbearing once the anterior ankle incision heals.7

Pros. The distal gastroc recession is a quick procedure for patients in the supine position. It allows isolated gastrocnemius or gastrocnemius-soleus lengthening depending on the level and depth of cut, and is sural nerve friendly. It leaves a less visible scar than the Baker procedure.

Cons. It is important to maintain an early stretch on the lengthened tissue to avoid equinus recurrence since the underlying soleus muscle tends to pull the two ends together.

Pearls For Performing The Endoscopic Gastroc Recession

Patient positioning, indications, degree of lengthening and recovery for endoscopic gastroc recession are similar to the Strayer technique with procedure selection largely based on surgeon preference. The risk profile regarding injury to the surrounding tissue depends on one’s technique and experience. Better visibility through the scope can potentially facilitate fewer nerve complications or less bleeding, although the procedure is technology-dependent, which can add time, cost and frustration. The endoscopic approach creates small medial and lateral scars.8

Pros. The endoscopic technique provides good visualization despite the small incision(s) and allows complete release from medial to lateral.

Cons. Setup can increase the operating time and cost, and many surgeons prefer direct visualization.  

A Guide To The Superficial Gastroc Recession

One generally performs the tongue and groove procedure, first described as a modification of the Vulpius procedure, with the patient in the prone position, which creates an added burden with many reconstructive procedures.

The midline posterior incision also creates a more visible scar. The surgeon achieves complete gastrocnemius and partial soleus lengthening due to performing the procedure below the conjoined tendon. The central incision allows direct visualization and retraction of the sural nerve, but even a well protected nerve can become problematic due to scar tissue. Photo 3 illustrates preoperative incision planning in relation to the location of the sural nerve as well as the orientation of the proximal and distal cuts. Immediate weightbearing is possible but less necessary than for a Strayer lengthening or endoscopic gastroc recession since the sutures are effective at avoiding both overlengthening and tendon retraction.

This is an ideal procedure for isolated lengthening like an ambulatory gastroc recession for metatarsal head ulceration or combined prone procedures such as combined plantar fasciotomy and gastroc recession.

Pros. This open procedure allows direct suture repair to avoid both overlengthening and tendon retraction. It also provides direct visualization of the sural nerve.

Cons. The superficial gastroc procedure is more challenging to perform with the patient supine. The surgery leaves a visible posterior scar and there can be possible nerve issues due to deep scar tissue.

Procedure Selection Considerations For Tendo-Achilles Lengthening

Tendo-Achilles lengthening procedures allow more aggressive correction of combined gastrocnemius-soleus complex equinus contractures.11 This is desirable for patients with certain conditions, including Charcot arthropathy, partial foot amputation with recurrent forefoot ulcerations, lifetime toe walkers and those with spastic contracture from neuromuscular conditions like cerebrovascular accident, cerebral palsy and traumatic brain injuries.

Patients with these conditions often require postoperative bracing, resulting in less concern for weakness or overlengthening in comparison to elective gastroc recession in young and/or active patients. The goal for many patients having tendo-Achilles lengthening is a 90-degree plantigrade foot that is braceable postoperatively.

What Are The Pros And Cons Of The Open ‘Z’ Tendo-Achilles Lengthening?

Open tendo-Achilles lengthening allows controlled lengthening since the surgeon is able to suture the tendon at the desired length (see photo 6). The main drawbacks involve the potential for poor wound healing and mild challenges with supine surgery. Prone positioning is ideal but surgeons commonly perform the procedure with the patient supine with an assistant holding the leg for exposure. The risk of sural nerve injury is low given the distal nature of the incision.

This is an ideal procedure for a lifetime toe walker or other type of moderate-severe ankle equinus with or without spastic contracture. Open exposure allows posterior ankle joint capsulotomy if necessary.

Pros. The open procedure offers controlled lengthening, more aggressive lengthening in comparison to gastroc recession for severe conditions and access to the posterior ankle joint if capsulotomy is necessary.

Cons. There is a potential for overlengthening or skin healing issues as well as possible tendon rupture.

How To Perform A Minimally Invasive Triple Hemi-Section Tendo-Achilles Lengthening

Minimally invasive triple hemi-section tendo-Achilles lengthening (otherwise known as the Hoke procedure) is easy to perform with three incisions for a patient in the supine position (see photo 9).9–11 Multiple small transverse incisions have higher healing potential in comparison to open tendo-Achilles lengthening. Transverse incisions are ideal for patients who have poor skin quality due to age, edema, peripheral vascular disease, neuropathy or chronic contracture. The zone of lengthening is a true tendo-Achilles lengthening as it is below the level of the soleus muscle. There is a low potential for sural nerve injury but overlengthening is possible due to the lack of control regarding final tendon length.10 Ideal patient selection takes into account spastic neuromuscular conditions in which the tendon is able to find the proper length once one applies the brace in a neutral position.11

Minimally invasive lengthening is less invasive from a surgical standpoint but more aggressive from a lengthening perspective. We commonly use this approach in patients in whom we desire more aggressive lengthening and overlengthening is less of a concern.

Pros. This procedure facilitates improved skin healing in patients with edema and/or peripheral vascular disease. One may perform the procedure as an in-office procedure for patients with advanced neuropathy and it offers immediate protected weightbearing for those with spastic equinus.

Cons. There is a potential for overlengthening and calcaneal gait as well as possible tendon rupture.

What You Should Know About The Percutaneous Achilles Tenotomy

Achilles tenotomy is basically a percutaneous release of the entire Achilles tendon, which one performs with the patient in the supine position. Indications are few and mostly include patients with severe equinus who need permanent rigid ankle-foot orthotic bracing, those with recurrent equinus or clubfoot patients after serial casting.12

The goal of surgery for patients with these chronic conditions is to make the extremity braceable by allowing rectus ankle alignment for neuromuscular spastic contracture and Charcot arthropathy. Soft tissue is often compromised in this patient population and advanced neuropathy may allow office-based surgery.

Pros. There is a low likelihood of recurrence of equinus. This percutaneous approach offers a minimalist approach in frail patients.

Cons. Patients can develop a calcaneal gait without bracing.

In Conclusion

We can view procedure selection among these different techniques to treat ankle equinus as either an opportunity or a challenge. While all approaches may work, guidelines are lacking to assist the surgeon with ideal procedure selection based on an individual patient’s operative needs. The majority of the literature involving equinus procedure selection is Level 3 or 4 evidence.13

This article highlights the multitude of factors that contribute to ideal procedure selection including positioning for adjunctive procedures (supine or prone), site of incision/visibility of scar, postoperative weightbearing status, proximity to the sural nerve, side effect profile and the degree of lengthening desired. Our approach is to incorporate all of these factors along with patient-specific indications for optimal procedure selection.

Dr. Boffeli is a board-certified foot and ankle surgeon practicing at HealthPartners Specialty Center in St. Paul, Minn. and Tria Orthopedics in Woodbury, Minn. He is a Fellow of the American College of Foot and Ankle Surgeons, and the Director of the Foot and Ankle Surgical Program at Regions Hospital/HealthPartners Institute for Education and Research.

Dr. Luer is a second-year resident in the Foot and Ankle Surgical Program at Regions Hospital/HealthPartners Institute for Education and Research.

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12.    Greenhagen RM, Johnson AR, Bevilacqua NJ. Gastrocnemius recession or tendo-Achilles lengthening for equinus deformity in the diabetic foot? Clin Podiatr Med Surg. 2012;29(3):413-24.
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By Troy Boffeli, DPM, FACFAS, and Samantha Luer, DPM
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