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Stage 2 PTTD: Is Osteotomy and Tissue Balancing Better Than Fusion?
POINT
Determining the best surgical treatment option for Stage 2 PTTD depends on many factors. Here the authors share evidence and their experience that supports that osteotomy and tissue balancing is superior to fusion in these cases.
By H. John Visser DPM, Rekha Kouri DPM, and Syed Rizvi, DPM
The original description and classification of posterior tibial tendon (PT) dysfunction and the creation of nomenclature for adult-acquired flat foot deformity came from Johnson and Strom in 1989.1 They described the clinical findings of the “too many toes” sign as a hallmark of this deformity.2,3 Stage I involved minimal deformity, managed in most instances via conservative means. Stage II was the flexible form with increased forefoot abduction, heel valgus, and equinus. Lastly, Stage III represented a fixed and rigid form of adult-acquired flatfoot deformity (AAFD).4
Since then, other conditions became included as part of the umbrella of adult-acquired flatfoot deformity, including posterior tibial tendon rupture, peritalar instability, osteoarthritis of the pedal joint structures, dorsolateral peritalar subluxation (PTS), and progressive talipes equinovalgus.3 These conditions also involve pathologic damage of the supporting structures, including the superficial and deep deltoid, talonavicular, spring, cervical and interosseous ligaments. This further adds to nomenclature confusion.5 As a result, a newer classification includes these extended pathologic conditions, described as progressive collapsing foot deformity (PCFD). PCFD represents a complex 3-dimensional deformity with varying degrees of rearfoot valgus, forefoot abduction, and midfoot varus.3,5
The Importance of PCFD in Procedure Selection
The classification of the condition of PCFD orients to 3 forms of consensus concerning treatment in the 2020 paper by Myerson and colleagues. The consensus, involving essential joints, aims to preserve pedal motion and avoid fusion/arthrodesis.3 Consensus 1 is designed to maximize and preserve joint mobility. The remaining consensuses stress only considering fusion with arthritic and/or severe deformities, as well as patients with high BMIs.
Preservation of the talonavicular joint remains critical to preservation of overall pedal mobility.3 Consideration will be given to operative approaches involving stage II progressive collapsing foot deformity where dysfunction of the peritalar complex only involves the posterior tibial tendon. Bluman and team advised a classification that includes four stages of progressive deformity.6
With the Bluman classification as a guide, one can employ surgical approaches to stage II AAFD that are comparable to the treatment of PCFD. This complex surgical algorithm provides essential joint function by the creation of joint alignment and balancing. Ultimately, preservation of joint motion then occurs with utilization of these surgical reconstructive techniques.
A patient with stage IIA1 deformity, as noted by Bluman and colleagues, has a supple flexible rearfoot valgus, flexible forefoot varus (supinatus), a possible positive Silfverskiold test, and pain and/or swelling along the course of the PT tendon.3 In this case, one addresses the equinus with either a Hoke percutaneous TAL or a Strayer gastrocnemius recession as determined by the Silfverskiold test.7 Although the Hoke percutaneous TAL only allows dorsiflexion to 90 degrees, one can perform it through two percutaneous incisions. The flexible rearfoot valgus represents compensation secondary to intratendinous tearing of the PT tendon. The muscle-to-tendon length ratio confers considerable weakness even with minimal injury. An assistive posterior varus-producing osteotomy of the calcaneus addresses the loss of strength with pathomechanical elongation of the tendon, mechanically reinforcing the PT tendon weakness. One must consider accumulative strength and evaluate tendon function in the vicinity. The FDL is 28 percent the strength of the PT tendon.3 This muscle-tendon structure (FDL) is oftentransferred to the navicular to reinforce the posterior tibialis tendon further. The peroneus brevis, which is an antagonist to the PT tendon, is only 69 percent as strong.8 Despite this fact, when the PT tendon is torn or pathologically lengthened, the peroneus brevis has a profound effect providing a retrograde pronation force at the subtalar joint.
In stage IIA1, there is a decreased Meary’s angle and a navicular-medial cuneiform fault. These normalize after equinus release and heel varus correction. One can perform a Jack test or Hubscher maneuver by dorsiflexing the hallux at the first MTPJ preoperatively on X-ray, and if the fault reduces, the midfoot is stable, and no surgery is necessary.9 Further options to the FDL tendon transfer is to further transfer the peroneus brevis to the longus. This removes a deforming force (PB) and increases the function of the peroneus longus with first ray plantarflexion.
Another option is the utilization of the tibialis anterior in a Young’s tenosuspension. Rerouting the tibialis anterior tendon through the navicular tuberosity serves to plantarflex the first ray and reduces the navicular-medial cuneiform fault, if present. It also gets further assistance from the peroneus longus after the tibialis anterior rerouting. Another option is the Cobb procedure. This uses a split portion of the tibialis anterior tendon to be rerouted across the medial cuneiform and then imbricated through the PT tendon to give it further strength.6 The tibialis anterior tendon strength as a unit is near 90 percent of the PT tendon.8
Bluman stage II A2 involves a more progressive loss of the posterior tibialis muscle and tendon function. There is more intratendinous damage in this case, but it remains intact. Relative stability against the peroneus brevis persists, determined radiographically by a normal cuboid abduction angle. Rearfoot valgus is present and again abreast with a medial varus displacement osteotomy (Koutsogiannis). The talar uncoverage angle is less than 40 degrees. Again, percutaneous TAL or gastroc recession addresses equinus.
The heel valgus and equinus combination affects the medial column, which presents as a Meary’s angle disruption. The apex centers at the naviculocuneiform fault (forefoot supinatus) mainly or occasionally at the first metatarsal medial cuneiform joint. This fault continues to persist with abnormal Meary’s angle. Operative procedures addressing this deformity include a Cotton osteotomy of the medial cuneiform; an opening wedge osteotomy with a structural graft (allograft, autograft, or cancellous titanium).7 A plantarflexing medial cuneiform osteotomy (Mosca) can also plantarflex the medial column to correct the forefoot supination. Though less commonly done, this procedure offers adductioncorrection of the first metatarsal medial cuneiform with osteotomy closure, due to maintenance of the ligamentous structures at the medial- intermediate cuneiform interface. If plantar gapping is present at the first metatarsal-medial cuneiform joint radiographically, then a Lapidus-type arthrodesis of this joint is an option.7 This is associated with forefoot varus deformity at the first medial cuneiform joint. The presence of hallux valgus deformity also represents first metatarsal medial cuneiform instability and should be addressed with Lapidus fusion. Of note, these fusion procedures involve non-essential joints.
Assessment of the condition of the muscle is essential. The presence of fatty infiltration or fibrosis on the MRI would lead to the consideration of tendon excision.10
An FDL transfer, a peroneus brevis-to-longus transfer, a Cobb or Young’s tenosuspension, or a posteriorcalcaneal osteotomy are also considerations. In addition, an Evans anterior calcaneal osteotomy will support the loss of this critical tendon. Transfer of the PT tendon to the fifth met base may also be useful. A PT allograft is a good option in cases where the muscle appears healthy on the MRI, or clinically but there is chronic scarring of the PT tendon and sheath with extension behind the ankle.3 If there is no extension of scarring behind the ankle, then surgeons may employ for use of treatment debridement, repair, and tenolysis which can be combined with a transfer of the peroneus brevis to the longus.
For stage IIB, there is rearfoot valgus, forefoot abduction, and a TN uncoverage angle greater than 40 degrees but not exceeding 50 degrees.7 In the presence of equinus, one performs a percutaneous tendo-Achilles lengthening or gastrocnemius recession. A double calcaneal osteotomy, which involves an Evans anterior calcaneal osteotomy with bone grafting and posterior medial displacement osteotomy, restores the talar uncoverage angle. Also, one might consider a STJ arthroereisis in patients with ligamentous laxity and obesity.11 One must additionally explore the condition of the spring ligament which is often torn in this stage. Options are direct repair in minor tears. More extensive degenerative tears by tendon imbrication or fiber tape interference screw technique. Stabilization of the talus within the pedal mortise is critical.
Supplemental posterior calcaneal osteotomy may occur in cases where removal is necessary later, restoring talocalcaneal alignment. FDL transfer and/or Cobb or Young’s tenosuspension procedure may also take place with a Cotton osteotomy. This realigns the ankle to the foot and helps establish neuromuscular balance. The surgeon repairs the tendon if possible but excision may become necessary if the tendon is extensively diseased or irreparable, as it can serve as a pain generator. In the last case, stage IIC is similar to stage IIB but the involvement of the medial column exhibits as first metatarsal-medial cuneiform joint instability. One addresses stage IIC similarly to stage IIB, but uses a first metatarsal-medial cuneiform joint arthrodesis for medial column stabilization.7
Final Thoughts
In conclusion, the surgical management for Stage 2 PTTD with osseous and soft tissue correction is not a definitive treatment for every patient case. However, the authors believe they are a powerful and better alternative for stage 2 PTTD than arthrodesis. Before considering a surgical plan, it is important to consider the patient’s age and health statuses, such as body mass index, and to have a deep understanding of the patient’s biomechanics. These procedures require that a surgeon evaluate each patient individually to assess which procedures would benefit their anatomy. The literature indicates the importance of joint preservation, especially in young and active individuals. Fusion is only indicate with arthritic and/or non-reducible deformities (talonavicular uncoverage angle greater than 50 degrees).7 Preservation of the talonavicular joint is critical because it is an essential joint. In conjunction with joint-sparing osteotomies, the wide variety of available soft tissue procedures allow for successful patient outcomes and satisfaction without sacrificing key biomechanical joints.
Dr. Visser is the Director of the Podiatric Residency Program at SSM Health DePaul Medical Center in St. Louis. He is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Foot and Ankle Surgery.
Dr. Kouri is a second-year podiatric resident at SSM Health DePaul Medical Center in Bridgeton, MO.
Dr. Rizvi is a first-year podiatric resident at SSM Health DePaul Medical Center in Bridgeton, MO.
COUNTERPOINT
Although they acknowledge that fusion may not be the best choice for all cases of Stage 2 PTTD, here the authors point out multiple key advantages over soft tissue balancing and osteotomy, both from the literature and in their specific practice.
By Troy J. Boffeli, DPM, FACFAS, Justin K. Metli, MA, DPM, and Garrett D. Nelson, DPM
Posterior tibial tendon dysfunction (PTTD) is a debilitating and progressive disorder that results in significant pain, weakness, restrictions with ambulation, and progressive flatfoot deformity. This disorder starts with tendinous changes, but will eventually lead to bony involvement if left untreated. Johnson and Strom initially described PTTD, and subsequently, Bluman and Myerson staged the disorder into 4 clinical stages based on the different pathoanatomies.1 The focus of this article is on stage 2 PTTD, which involves more permanent changes in the posterior tibialis (PT) tendon. These changes lead to a functionally incompetent PT tendon, allowing the foot to take on a pes plano valgus position.2 A collapsed medial longitudinal arch characterizes this deformity, with forefoot abduction through the talonavicular joint, and hindfoot valgus through eversion of the subtalar joint (STJ).
Examining the Available Treatment Options
There are multiple different historical treatment options used for stage 2 PTTD. By definition, stage 2 “should not have any associated arthropathies.” Therefore, didactically, soft tissue procedures are often preferrable over bone and joint reconstruction.1 The treatment of choice is usually a tendon transfer, commonly the flexor digitorum longus (FDL) or flexor hallucis longus (FHL). However, an isolated tendon transfer does not provide a protective mechanism against premature reelongation or rerupture because it does not anatomically realign the foot and restore rectus biomechanics. Therefore, adjunctive flatfoot reconstructive procedures will allow the tendon transfer to function more effectively. The typical approach for stage 2 disease involves gastrocnemius lengthening, extra-articular osteotomy of the calcaneus (anterior, posterior, or both), Cotton osteotomy or medial column fusion, and repair of the PT tendon as needed. We previously published an algorithm to assist with medial column procedure selection, and this discussion will focus on rearfoot procedure selection.3
Is Staging Enough? Considering the Best Treatment Pathways
As with all foot and ankle pathology, not all patients fall perfectly into the staging classifications, and therefore treatment modalities need to be patient-specific. Staging criteria for PTTD do not consider patient-specific factors like planal dominance of the flatfoot disorder, patient age, occupation, athletic interests, or body mass index (BMI). A young, active, athletic patient who develops stage 2 PTTD from excessive running on a mildly flattened foot type may need a different approach than a middle-aged, overweight, inactive patient with a preexisting severe flatfoot deformity. Additionally, a patient experiencing synovial impingement of the sinus tarsi due to excessive pronation of the STJ associated with PTTD may not find relief from extraarticular procedures.
In general terms, we focus on extraarticular procedures in younger and more active patients with stage 2 PTTD who can expect adequate correction of deformity with joint-sparing rearfoot procedures. One isolates arthrodesis of the rearfoot to the STJ for Stage 2 PTTD with the expectation of restoring midtarsal joint alignment without the need to fuse the talonavicular or calcaneocuboid joints. The pes plano valgus deformity occurs mainly through the transverse tarsal joints, particularly the talonavicular and subtalar joints.2 The STJ arthrodesis focuses on the periarticular subluxation deformities by directly addressing the hindfoot valgus. Once the surgeon corrects the inferomedial rotation of the calcaneus beneath the talus, this indirectly increases the stability of the transverse tarsal articulations, providing a more efficient relationship between the midfoot and hindfoot, and thus taking the stress off the PT tendon.4 This increased stability preserves significant motion at the transverse tarsal joints and addresses one of the main concerns with hindfoot arthrodesis, loss of motion causing compensatory arthritis of adjacent joints.
Mann and colleagues reported mild radiographic evidence of arthrosis in adjacent joints with an average 5-year follow-up of 48 STJ fusions, all of which were asymptomatic.5 Russotti and team reported no significant progression of arthrosis at adjacent joints in 45 STJ fusions with an average 5-year follow-up.6 Astion and colleagues noted that approximately 50 percent of the normal excursion rate of the PT tendon is salvageable with the isolated STJ arthrodesis.7 This procedure allows one to maintain long-term maintenance of the hindfoot alignment with minimal gait alterations and correction of all 3 major components in the flexible flatfoot. The STJ arthrodesis is a highly reproducible procedure that provides a plantigrade foot and yields high rates of union with low complication rates, ultimately restoring proper biomechanical advantage to the PT tendon.
When is Arthrodesis Superior?
STJ arthrodesis may not carry a primary indication for stage 2 PTTD according to the staging algorithm, but patients commonly have more severe deformities or comorbidities that make it the preferred treatment option. The decision to recommend STJ fusion over single or double heel osteotomy primarily depends on these patient-specific factors. Some patients present with severe STJ pronation and experience lateral column pain due to sub-fibular or sinus tarsi impingement more so than actual PT tendon pain. Sinus tarsi impingement is a direct result of the pronation through the STJ, which one addresses when rectifying the rotatory alignment of the talus and calcaneus with STJ fusion. Fusion of the STJ may be a more predictable approach to correct the foot at the apex of the deformity under these circumstances.
When a patient presents with early degenerative changes of the STJ, in our experience, the STJ arthrodesis will correct the pes plano valgus deformity with the added benefit of proactively stopping the progression of arthrosis. Periarticular procedures may provide relief if the STJ functions postoperatively in a less pronated position, but a middle-aged, low-impact activity, overweight patient wants the most predictable approach to restoring pain-free function. This patient wants to walk, golf, and work without pain and will rarely complain that they lost some inversion and eversion to achieve their desired goals. STJ fusion can be a viable option for these patients that yields restoration of rearfoot on forefoot alignment with excellent reproducibility and long-term benefits regarding restoration of PT tendon function.
In Conclusion
Overall, procedure selection for stage 2 PTTD is not a one-size-fits-all since patients present with various symptoms. Disadvantages of the STJ arthrodesis involve limiting hindfoot motion and the risk of symptomatic adjacent joint arthrosis. However, STJ fusion is a well-studied, reproducible procedure with low complications and a high rate of advantages and success for the proper patient. These advantages stem from the long-term maintenance of hindfoot alignment, which stabilizes the transverse tarsal joints. This ultimately preserves motion and provides a more functional relationship between the midfoot and hindfoot, as well as restores the functionality of the PT tendon. Other advantageous factors are the treatment of early degenerative changes within the STJ and reducing the lateral hindfoot pain that presents from sinus tarsi impingement. STJ arthrodesis can be a beneficial treatment option for those with stage 2 PTTD who may present with multiple comorbidities, obesity, older age, low-impact activities, or lateral impingement. n
Dr. Boffeli is the Foot and Ankle Surgical Residency Program Director and Department Chair at Regions HospitalHealthPartners Medical Group in St. Paul, Minn.
Dr. Metli is a first-year resident at Regions HospitalHealthPartners Medical Group in St. Paul, Minn.
Dr. Nelson is a second-year resident at Regions HospitalHealthPartners Medical Group in St. Paul, Minn.
Point References
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