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Is The Standard Of Care Evolving For Adult-Acquired Flatfoot?

“Standard of care” is a misunderstood term amongst physicians, yet it impacts everything we do regarding our patients' care. Legally, medical malpractice falls under the general category of negligence in law.1 A plaintiff’s attorney must demonstrate four elements (duty; breach of duty; harm; and causation) to recover damages.1 Breach of duty most closely relates to standard of care. The modern legal definition of standard of care based on legal precedent from Hall v. Hilbun, McCourt v. Abernathy and Johnston v. St. Francis Medical Center is "That which a minimally competent physician in the same field would do under similar circumstances."1-4 

A key phrase in the definition is "in the same field." Does that mean podiatry for podiatric physicians or other foot and ankle providers, for example, orthopedic foot and ankle surgeons? The American Orthopaedic Foot and Ankle Society (AOFAS) recently issued a set of consensus statements regarding adult flexible flatfoot deformity. These statements, published in Foot and Ankle International as a series of articles, establish standard of care for flatfoot surgery.5-14 In the Guest Editorial, de Cesar Netto and colleagues stated, "We, therefore, sought to guide ourselves and colleagues in a more immediate fashion. We also followed the precedent set by our colleagues to form consensus group statements in the area of ankle cartilage injuries and musculoskeletal infection."14  

A New Approach To Nomenclature And Classification Of Adult-Acquired Flatfoot

The consensus group (CG) changed the terminology from adult flexible flatfoot deformity to progressive collapsing foot deformity (PCFD) as they felt the latter better described the condition.14 The classification system established by the CG addressed the deficiencies of the Johnson and Strom classification along with that of Bluman and team.15,16  According to the consensus group, progressive collapsing foot deformities are flexible (1) or rigid (2).5 Progressive collapsing foot deformities specifically may be isolated or combined and one classifies them by type, based on consistent clinical and radiographic findings.5

1. Class A: hindfoot valgus (hindfoot valgus alignment; increased hindfoot moment arm, hindfoot alignment angle, foot and ankle offset)

2. Class B: midfoot/forefoot abduction deformity (decreased talar head coverage; Increased talonavicular coverage angle; presence of sinus tarsi impingement)

3. Class C: forefoot varus deformity/medial column instability (increased talus–first metatarsal angle; plantar gapping at first tarsometatarsal joint/naviculocuneiform joints; clinical forefoot varus)

4. Class D: Peritalar subluxation/dislocation (significant subtalar joint subluxation/subfibular impingement) 

5. Class E: Ankle instability (valgus tilting of the ankle joint)5 

For example, under the system proposed by the consensus group, a deformity with a flexible hindfoot valgus, a fixed forefoot varus, sinus tarsi pain with flexible peritalar subluxation and no radiographic evidence of ankle valgus as ‘1AD2C.’

A Closer Look At Updated Recommendations For Evaluation And Management

The AOFAS Consensus Group recommendations for radiographic examination of PCFD include weight-bearing anteroposterior (AP) foot, AP or mortise ankle, and lateral foot and hindfoot alignment views.8 When available, the Consensus Group also strongly recommends weight-bearing computed tomography (CT) for surgical planning.

General goals for surgical correction recommended by the CG include:6

• maximizing preservation of joint range of motion and mobility;

• talonavicular (TN) joint fusion should be considered in arthritic and stiff joints and/or sagittal plane sagging of the TN joint, severe deformities, as well as in cases where inadequate correction of the talonavicular abduction deformity is achieved intraoperatively; and 

• patients with high body mass index (BMI) (equal to or higher than 30), will generally do worse with reconstructive surgery when compared to hindfoot fusions.6

A medializing calcaneal displacement osteotomy (MDCO) as an isolated bony procedure is indicated with an isolated hindfoot valgus deformity with adequate talonavicular joint coverage (less than 35 to 40 percent uncovering) and lack of significant forefoot supination, varus or abduction.10 The goal of an MDCO is a clinically neutral hindfoot position, with osteotomy displacement ranging from seven to 15 mm of displacement.10 

Intraoperatively when talonavicular uncoverage exceeds 40 percent, with the hindfoot placed in a corrected position, a lateral column lengthening (Evans osteotomy) is indicated.7 One should determine correction intraoperatively which typically ranges between five to 10 mm.7 One should take care to avoid overcorrection by using simulated weight-bearing fluoroscopic evaluation of the talonavicular joint.7

The presence of subtalar joint arthritis and stiffness or severe peritalar subluxation/dislocation are indications for a subtalar arthrodesis.13 In the correction of the forefoot varus component of progressive collapsing foot deformities, naviculocuneiform (NC) joint fusion is indicated when the naviculocuneiform joint is arthritic and symptomatic and/or when there is significant sagittal plane sagging of that joint.13

A stable medial longitudinal column is critical for the restoration of a balanced foot tripod.11 Forefoot varus is a clinical measurement evaluated after one corrects the hindfoot. A Cotton osteotomy corrects a forefoot varus with a wedge size between five to 11 mm.11 First ray instability does not preclude the use of a Cotton osteotomy. However, the presence of gross clinical instability of the first ray and/or radiographic plantar gapping of the first tarsometatarsal joint are indications for first tarsometatarsal joint fusion.11

Medial soft tissue procedures (spring ligament/superficial and deep deltoid repair/reconstruction) or a talonavicular fusion are recommended when there is incomplete correction of the abduction deformity after an Evans osteotomy.12 The amount of lateral talar dome cartilage loss determines the type of ankle valgus correction. In deformities with less than 50 percent lateral cartilage loss, medial soft tissue procedures are recommended, whereas deformities with greater than 50 percent lateral cartilage loss, ankle arthrodesis or arthroplasty become indicated.12

One crucial component of flatfoot deformity the Consensus Group did not comment on is equinus. The authors stated, “The topic of gastrocnemius/Achilles tightness, although certainly important in the pathophysiology of the collapsing flatfoot, was not chosen given its controversial nature, the difficultly to reach consensus, and the lack of data to support consensus statement rationale.”14

Final Thoughts

I find these consensus statements logical, well thought-out, as evidence-based as possible and practical. How these statements may impact standard of care for the treatment of flatfoot deformity is yet to be determined. In my opinion the AOFAS Consensus Group  not only provided guidelines for physicians treating progressive collapsing foot deformity, but also established standard-of-care. 

Dr. DeHeer is the Residency Director of the St. Vincent Hospital Podiatry Program in Indianapolis. He is a Fellow of the American College of Foot and Ankle Surgeons, a Fellow of the American Society of Podiatric Surgeons, a Fellow of the American College of Foot and Ankle Pediatrics, a Fellow of the Royal College of Physicians and Surgeons of Glasgow, and a Diplomate of the American Board of Podiatric Surgery.

References 

1. Moffett P, Moore G. The standard of care: legal history and definitions: the bad and good news. Western J Emer Med. 2011;12(1):109.

2. Hall v. Hilbun, 466 So. 2d 856 (Miss. 1985). Casetext. Available at: https://casetext.com/case/hall-v-hilbun-1 . Accessed March 22, 2021.

3. McCourt v Abernathy, 457 S.E.2d 603 (S.C. 1995). Global Health and Human Rights Database. Available at: https://www.globalhealthrights.org/health-topics/health-care-and-health-services/mccourt-v-abernathy/ . Accessed March 22, 2021.

4. Johnston v. St. Francis Medical Center, Inc., No. 3 5, 236-CA, Oct. 31, 2001. Findlaw. Available at: https://caselaw.findlaw.com/la-court-of-appeal/1095863.html . Accessed March 22, 2021.

5. Myerson MS, Thordarson DB, Johnson JE, et al. Classification and nomenclature: progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1271-1276.

6. Sangeorzan BJ, Hintermann B, de Cesar Netto C, et al. Progressive collapsing foot deformity: consensus on goals for operative correction. Foot Ankle Int. 2020;41(10):1299-1302.

7. Thordarson DB, Schon LC, de Cesar Netto C, et al. Consensus for the indication of lateral column lengthening in the treatment of progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1286-1288.

8. de Cesar Netto C, Myerson MS, Day J, et al. Consensus for the use of weightbearing CT in the assessment of progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1277-1282.

9. Ellis SJ, Johnson JE, Day J, et al. Titrating the amount of bony correction in progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1292-1295.

10. Schon LC, de Cesar Netto C, Day J, et al. Consensus for the indication of a medializing displacement calcaneal osteotomy in the treatment of progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1282-1285.

11. Johnson JE, Sangeorzn BJ, de Cesar Netto C, et al. Consensus on indications for medial cuneiform opening wedge (Cotton) osteotomy in the treatment of progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1289-1291.

12. Deland JT, Ellis SJ, Day J, et al. Indications for deltoid and spring ligament reconstruction in progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1302-1306.

13. Hintermann B, Deland JT, de Cesar Netto C, et al. Consensus on indications for isolated subtalar joint fusion and naviculocuneiform fusions for progressive collapsing foot deformity. Foot Ankle Int. 2020;41(10):1295-1298.

14. de Cesar Netto C, Deland JT, Ellis SJ. Guest editorial: expert consensus on adult-acquired flatfoot deformity. Foot Ankle Int. 2020;41(10):1269-1271.

15. Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop Related Res. 1989;239:196-206.

16. Bluman EM, Title CI, Myerson MS. Posterior tibial tendon rupture: a refined classification system. Foot Ankle Clin. 2007;12(2):233-249.

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