Understanding And Managing Equinus Deformities

Equinus often lies at the root of a wide variety of foot and ankle conditions although the prevalence of the deformity is not universally recognized. This author details the incidence of equinus and shares his perspectives on its impact, pertinent surgical considerations and the benefits of endoscopic gastrocnemius recession.

Hallux valgus, hallux rigidus, metatarsalgia, capsulitis, adductovarus contracture of the fifth digit, pes valgo planus, hypermobility of the first ray, hammer digit syndrome, clinodactyly, lateral column syndrome, sesamoiditis and plantar fasciosis are all common conditions of the foot. What do they all have in common? Most often, there is an accompanying limitation of ankle joint dorsiflexion: equinus.1,2

   It is universally accepted that equinus can be due to several different etiologies. These etiologies include:
• bony block between the talus and distal tibia (osseous equinus);
• contracture or tightness of the soleus muscle (soleal equinus);
• contracture or tightness of the soleus and gastrocnemius muscles (gastroc-soleal equinus);
• isolated tightness of the gastrocnemius muscles (gastrocnemius equinus); and
• compensatory loss of ankle joint range of motion for some other condition such as pes cavus (pseudoequinus).

   In my clinical experience, gastrocnemius tightness accounts for approximately 85 percent of all equinus. However, it is not universally accepted in orthopedic and podiatric surgery that gastrocnemius equinus is primarily causal in many of the aforementioned common pedal conditions.

   In their 2002 Journal of Bone and Joint Surgery article, DiGiovanni and colleagues eloquently state the following:1

    “Except for a few still controversial examples of plantar fasciitis, forefoot ulceration in diabetics, or progressive hallux valgus or flatfoot, the relationship between tightness of the superficial posterior compartment and progressive pathological changes in the foot in non-spastic individuals has been overlooked entirely by the orthopaedic community. In contradistinction, more attention has been paid to this phenomenon in the podiatric literature over the past three decades …”

   However, it is my contention that even in podiatric surgery, equinus accounts for the overwhelming majority of pedal pathology and is largely ignored even when one appreciates it via an accurate diagnosis and thorough biomechanical understanding.

   Foundational treatment of equinus with a minimally invasive, endoscopic gastrocnemius recession (EGR) technique can effectively treat global pathology. The endoscopic gastrocnemius recession obviates the frequently devastating sequelae one sees with extensive forefoot reconstruction and reduces the postoperative morbidity associated with these more extensive surgeries. In addition, the procedure eliminates the deforming causative force, which is likely to contribute to ongoing pathology.

What One Survey Revealed About Equinus Diagnosis And Treatment

For example, several years ago Podiatry Today ran a survey on the diagnosis and treatment of equinus (see https://tinyurl.com/43peeqc ). Two hundred sixty-nine people completed the survey. Only 5.58 percent (17 respondents) never made the diagnosis of equinus. Two hundred fifty-four (94.42 percent) of the 269 respondents diagnosed the condition monthly with 97 (36 percent) making the diagnosis more than 10 times per month, 59 (22 percent) six to 10 times per month, and 98 (36 percent) diagnosing the condition one to five times per month.

   However, when asked “How often do you surgically treat equinus?,” 147 respondents replied “never” (54.65 percent) while 113 responded “yes” in 25 percent or less of their cases.

   Clearly, there is still a huge conceptual abyss that exists today between the recognition of and the surgical treatment of equinus as evidenced by this small sample of foot surgeons. Ninety-seven percent make the diagnosis but only 54 percent surgically treat the condition, sometimes very infrequently. There are several reasons for this in light of the compelling widespread clinical evidence and the amount of literature, which strongly supports the biomechanical relationship between the lack of ankle joint dorsiflexion and the development of pedal pathology.

A Closer Look At The Prevalence And Impact Of Equinus

First, let us again take a look at the prospective study by DiGiovanni and colleagues to see how prevalent equinus is in patients with foot pathology.1 The authors assessed a control group of 34 patients who never had foot pathology and 34 patients who presented with “isolated” forefoot or midfoot pain. They screened 1,000 patients to get this 34 due to their exclusion criteria. The researchers excluded any patient with neuroma or neurological conditions, any hindfoot or ankle pathology or a myriad of other reasons.

   The authors found that if they used less than 10 degrees of dorsiflexion with the knee extended as normal, 88 percent of the patients with pathology had equinus in comparison to 44 percent in the control group.1 When using only 5 degrees or less as the “normal” dorsiflexion, 65 percent of the pathology group had equinus versus 24 percent of the control group.

   What would the numbers be if their selection criteria were not based on isolated foot pathology but included global pathology? It is very likely the percentage of patients with pathology and equinus would be higher than 88 percent.

   In support of this contention is a prospective study of 174 consecutive patients out of 209 who met the selection criteria.3 They were subdivided into the following groups: rearfoot pain, medial foot pain, lateral foot pain and mixed etiology pain. Of the 174 patients, 168 (97 percent) had less than 3 degrees of dorsiflexion.

   Perhaps the greatest reason that gastrocnemius equinus, or all equinus for that matter, is undertreated is simply because of our current paradigm of surgical training and understanding. In a 2008 Podiatry Today article I co-authored, I related an interview I had with Thomas Sgarlato, DPM.4 Dr. Sgarlato had shared the following:

    “… in 1963, Root was doing tendo-Achilles lengthenings and McGlamry was doing tongue in groove gastrocs while I discovered you could just release the medial gastroc. Podiatry was in the dark ages then and we did not have the tools to react to it (equinus) … The problem is training. If more podiatric surgeons were trained to do the technique, and especially with the endoscopic approach that we did not have, more people would be helped.” (See www.podiatrytoday.com/what-role-does-equinus-play-in-heel-pain )

   If the aforementioned survey results are representative of the entire profession, then it is impossible to attribute the relative lack of surgical treatment to diagnosis, recognition and understanding the condition. Even as early as 1971, Subotnick boldly and accurately stated that equinus “is the greatest symptom producer in the foot.”2

   Consider the following compelling facts.
• Equinus is the single biggest risk factor for plantar fasciosis with a 23.3-fold odds ratio for the development of the condition.5
• DiGiovanni’s 2002 study showed that 88 percent of patients with foot pathology have equinus.1
• Bowers and Castro clinically observed a 50 to 60 percent incidence of equinus in all patients examined for any foot or ankle problem.6
• Hill found that 96.5 percent of patients who presented with foot pain had equinus.4
• Increased tension in the Achilles tendon transfers directly to increased tension in the plantar fascia.7
• Lavery, Armstrong and Bolton evaluated 1,666 consecutive patients with diabetes and found those with equinus (and their definition of equinus was 0 degrees of dorsiflexion) had a threefold chance of increased peak plantar pressures, which are known to increase the chance of ulceration.8
• In 30 children with neuro-spasticity who were initially evaluated and noted to have no foot deformity prior to weightbearing, 19 developed hallux valgus after walking while the other 11 developed an adducted forefoot.9 This evidence alone provides an irrefutable demonstration that equinus is a causative factor in the development of forefoot pathology.

   Yes, there is the argument for conservative care. However, when gastrocnemius equinus is significantly present with an associated formidable forefoot global deformity, is there really anything conservative about performing an extensive forefoot reconstruction without addressing the tightness of the posterior superficial compartment of the leg?

   Grady and Saxena showed an improvement of only a few degrees after different levels and times of stretching of the gastrocnemius muscle.10 Evans in fact showed that only six of 20 patients were able to reach 10 degrees of dorsiflexion after use of night splints ranging from six weeks to one year.11

   This brings to light two important questions. Aren’t those patients with significant demonstrative pathology likely to need more than 3 degrees of improvement in dorsiflexion to ameliorate their mechanical overload? Do we really need to stretch the muscle or the aponeurosis? The tensile strength that would be required to stretch the aponeurosis would far exceed the force required to maintain normal ligamentous and tendon integrity of the midfoot during the stretch.12

Key Surgical Considerations

Historically, the surgical paradigm to treat equinus, although well delineated, has not evolved to correlate with the improvement in current surgical techniques.

   Equinus can be difficult to measure or assess clinically from practitioner to practitioner. As DiGiovanni points out, clinicians are accurate 97.2 percent of the time if equinus contracture is defined as less than 10 degrees of dorsiflexion.13 Accuracy falls to 77.8 percent if 5 degrees is the benchmark. From a pragmatic point, in addition to the vast amount of literature, which supports the need for 10 degrees of dorsiflexion at the level of the ankle joint for normal biomechanical function, clinicians would obviously be more accurate in assessing whether the patient has less than 10 degrees of dorsiflexion with the knee extended.

   Clinically, individual practitioners easily and accurately make the diagnosis but the assessment of the true number of degrees may vary widely with different practitioners. The description of the Silfverskiold maneuver has been well delineated for practitioners to determine what type of equinus is present. It is important to note that when there is no dorsiflexion available with the knee flexed and one has identified a bony block, there is almost always the need for posterior soft tissue release after surgical elimination of the bony impingement as the triceps surae are contracted.

   When it comes to surgical reconstruction for conditions such as hallux valgus, hammer digit syndrome, metatarsalgia, capsulitis, flatfoot, posterior tibial tendon insufficiency syndrome, Morton’s entrapment, hallux limitus/rigidus, plantar fasciosis, Charcot arthropathy, Achilles tendinosis/posterior or calcaneal exostosis, one should seriously contemplate a simultaneous gastrocnemius recession or even performing this prior to the planned surgical reconstruction.

   When it comes to complex forefoot deformity, it has been my experience that carefully planned serial surgery and performing the gastrocnemius recession as the primary procedure decreases the actual amount of surgical procedures and often completely eliminates the need for a second surgery. I recommend reassessment of the forefoot condition three to six months after superficial posterior compartment release. In many cases, the forefoot symptoms have resolved to the point where additional surgical procedures are simply not required or, if there is still pathology, there is a much lesser degree requiring less tissue disruption.

   This is well illustrated in the patient who has complaints of slightly contracted lesser digits, neuritic symptoms such as Morton’s entrapment in one or both interspaces, and a diffuse hyperkeratosis of the plantar forefoot.14 It is conservative, far simpler and less involved for the patient to undergo a minimally invasive endoscopic gastrocnemius recession. This allows full, immediate weightbearing in a boot in comparison to panmetatarsal osteotomies, multiple level procedures for lesser digital contracture and resection of a common plantar digital nerve or two.

   There is no comparison of the postoperative morbidity associated with each of these two different approaches. It is incredible how often the forefoot maladies just disappear a few months after a gastrocnemius recession. Often, the planned serial or staged surgical approach is simply not needed with reestablishment of normal forefoot and rearfoot biomechanical function. When one explains this concept to patients, they usually accept it readily.

What You Should Know About Performing An Endoscopic Gastrocnemius Recession

The advantages of the endoscopic approach to gastrocnemius recession are not only limited to the lesser invasive nature of the procedure but also to the fact that one can easily perform it with the patient in the supine position, and it does not increase intraoperative time for the surgeon. I have previously described my surgical technique using the Endotrac system (Instratek).4 There have been relatively few technique changes since then. However, as with any surgical technique, increased surgical experience combined with critical assessment has led to more refinements, which I have learned both in teaching the technique as well as performing it.

   Since exact precision is required for ideal anatomical placement of the endoscopic instrumentation in any endoscopic surgical technique to afford maximum outcomes, there are a couple of pearls that can aid the surgeon. In a 2005 publication, we presented results from a cadaveric anatomic study of 28 embalmed specimens.15 We were able to describe an “endoscopic zone” for proper placement of the cannula for an endoscopic gastrocnemius recession. It should be noted that in contrast to endoscopic decompression of intermetatarsal nerves and endoscopic plantar fasciotomy, there is more latitude for placement of the endoscopic gastrocnemius recession instrumentation while still being able to perform the procedure successfully.16-19

   The surgical technique should begin with appreciation of the topical anatomy with palpation of the “edge” of the medial aspect of the gastrocnemius aponeurosis on the medial aspect of the calf within the “endoscopic zone.” This is where one should place the medial portal incision. Separation with blunt dissection of the subcutaneous fat allows the surgeon to palpate the dense tissue of the aponeurosis.

   Usually, there is minimal (2 to 5 mm) subcutaneous fat between the dermis and this tissue plane. In some patients, there is virtually no subcutaneous tissue and the passage of the instrumentation feels like it is just below the skin. After establishing this surgical plane, one can use an elevator to separate the subcutaneous fat from the superficial surface of the aponeurosis.

   Performing this step judiciously facilitates maximum protection of the sural nerve from injury. However, the surgeon must take caution as nerve injury can occur even with the most exact and refined surgical technique. Considering that this is only a cutaneous nerve with a small amount of innervation, and that it is the biopsy and donor nerve of choice, the risk is relatively small in comparison to the maximal benefit of improvement in biomechanics for the patient.

   True sural nerve injury occurs only rarely, almost always without any sequelae except for “numbness,” but the patient can end up with an amputation neuroma, which could require revision surgery. Neuropraxia of the sural nerve is common. However, due to the subsequent traction of the sural nerve with the increased range of dorsiflexion, this is almost always transient and fades within six to eight weeks.

   Once you have placed the instrumentation, it is recommended to begin the transection of the aponeurosis from medial to lateral as there is often only a need for a medial one-third release to reach the desired level of dorsiflexion. If more tissue is required to be cut, it can be based on the intraoperative assessment by the surgeon. Many times, in severe cases, it has been my experience that a complete medial to lateral release is needed.

Essential Postoperative Pearls

The postoperative management of the endoscopic gastrocnemius recession technique is subordinate to the extent required by other simultaneously performed procedures. If one only performs an isolated endoscopic gastrocnemius recession, then patients can immediately bear weight in a tall walking boot. Encourage the patient to remove the boot and perform gentle active movement of the ankle, foot and lower leg. Casting or other complete immobilization is not recommended as this could increase the possible development of a deep venous thrombosis.

   Within the last two years, my postoperative regimen includes the use of an intermittent compression and cooling device, which has greatly reduced postoperative edema and discomfort. Preferably, one should have the patient using the device the day of surgery. The endoscopic gastrocnemius recession is usually a minimally painful procedure if one performs it properly.

In Summary

Surgeons who add surgical treatment of equinus (whether endoscopic or open) to their armamentarium, if it is not already present, will find optimization of patient surgical outcomes and increased patient satisfaction. For many surgeons, this will require a huge mental paradigm shift but, in my opinion, the overwhelming improvement in patient outcomes will make the surgeon glad to have embraced the seemingly difficult change.

   The minimally invasive endoscopic gastrocnemius recession technique allows for improved lower extremity biomechanical function, which frequently obviates the need for additional surgical procedures, many of which have a greatly increased postoperative morbidity. Additionally, since the endoscopic gastrocnemius recession frequently allows for the obviation of what patients thought would be required from a planned surgical reconstruction, sometimes they perceive the procedure as relatively “non-invasive.”

   Dr. Barrett is an Adjunct Professor within the Arizona Podiatric Medicine Program at the Midwestern University College of Health Sciences. He is a Fellow of the American College of Foot and Ankle Surgeons.

   Dr. Barrett is a paid medical consultant for Instratek, Inc., which manufactures the instrumentation used in this endoscopic gastrocnemius recession technique. He has no financial relationship with Maldonado Medical, the company that manufactures the TEC system.

References

1. DiGiovanni CW, Kuo R, Tejwani N, Price R, Hansen ST Jr., Cziernecki J, Sangeorzan BJ. Isolated gastrocnemius tightness. J Bone Joint Surg Am. 2002; 84-A(6):962-970.
2. Subotnick SI. Equinus deformity as it affects the forefoot. J Am Podiatry Assoc. 1971; 61(11):423-427.
3. Hill RS. Ankle equinus. Prevalence and linkage to common foot pathology. J Am Podiatr Med Assoc. 1995; 85(6):295-300.
4. Barrett SL, Whiting T. What role does eqinus play in heel pain? Podiatry Today. 2008; 21(11):44-54.
5. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: a matched case-control study. J Bone Joint Surg Am. 2003; 85-A(5):872-877.
6. Bowers AL, Castro MD. The mechanics behind the image: foot and ankle pathology associated with gastrocnemius contracture. Semin Musculoskelet Radiol. 2007; 11(1):83-90.
7. Erdemir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA. Dynamic loading of the plantar aponeurosis in walking. J Bone Joint Surg Am. 2004; 86-A(3):546-552.
8. Lavery LA, Armstrong DG, Boulton AJ. Ankle equinus deformity and its relationship to high plantar pressure in a large population with diabetes mellitus. J Am Podiatr Med Assoc. 2002; 92(9):479-482.
9. Holstein A. Hallux valgus--an acquired deformity of the foot in cerebral palsy. Foot Ankle. 1980; 1(1):33-38.
10. Grady JF, Saxena A. Effects of stretching the gastrocnemius muscle. J Foot Surg. 1991, 30(5):465-469.
11. Evans A. Podiatric medical applications of posterior night stretch splinting. J Am Podiatr Med Assoc. 2001; 91(7):356-360.
12. DiGiovanni CW, Langer P. The role of isolated gastrocnemius and combined Achilles contractures in the flatfoot. Foot Ankle Clin. 2007; 12(2):363-379, viii.
13. Digiovanni CW, Holt S, Czerniecki JM, Ledoux WR, Sangeorzan BJ. Can the presence of equinus contracture be established by physical exam alone? J Rehabil Res Dev. 2001; 38(3):335-340.
14. Barrett SL, Jarvis J. Equinus deformity as a factor in forefoot nerve entrapment: treatment with endoscopic gastrocnemius recession. J Am Podiatr Med Assoc. 2005; 95(5):464-468.
15. Carl T, Barrett SL. Cadaveric assesment of the gastrocnemius aponeurosis to assit in the pre-operative planning of two portal endoscopic gastrocnemius recession (EGR). The Foot. 2005; 15(3):137-140.
16. Barrett SL, Pignetti TT. Endoscopic decompression for intermetatarsal nerve entrapment--the EDIN technique: preliminary study with cadaveric specimens; early clinical results. J Foot Ankle Surg. 1994; 33(5):503-508.
17. Barrett SL, Walsh AS. Endoscopic decompression of intermetatarsal nerve entrapment: a retrospective study. J Am Podiatr Med Assoc. 2006; 96(1):19-23.
18. Barrett SL. Endoscopic plantar fasciotomy. Clin Podiatr Med Surg. 1994; 11(3):469-481.
19. Barrett SL, Day SV. Endoscopic plantar fasciotomy: two portal endoscopic surgical techniques--clinical results of 65 procedures. J Foot Ankle Surg. 1993; 32(3):248-256.

   For further reading, see “What Role Does Equinus Play In Heel Pain?” in the November 2008 issue of Podiatry Today, “Pertinent Pointers On Equinus Procedures” in the June 2007 issue or “Key Insights On The Role Of Equinus In Foot Pain” in the May 2007 issue. To access the archives, visit www.podiatrytoday.com.