Naviculocuneiform Sag in the Acquired Flatfoot: What to Do

Medial Column Fusions in Flatfoot Deformities: Naviculocuneiform and Talonavicular

Progressive collapsing foot deformity (PCFD; commonly referred to as flatfoot deformity) is a complex condition classically characterized by hindfoot valgus, midfoot abduction, and forefoot varus. Medial column arthrodesis can be used to reliably correct severe, arthritic, and unstable PCFD involving the medial column. Although both naviculocuneiform arthrodesis and talonavicular arthrodesis have their own indications, patient selection and careful radiographic and clinical assessment are crucial for any medial column arthrodesis. Herein, the authors discuss the indications for medial column arthrodesis procedures, outcomes as reported in the literature, and several case examples using medial column arthrodesis in deformity correction.

Intra- and Interobserver Reliability of the New Classification System of Progressive Collapsing Foot Deformity

BACKGROUND

Historical concept of flatfoot as posterior tibial tendon dysfunction (PTTD) has been questioned. Recently, the consensus group published a new classification system and recommended renaming PTTD to Progressive Collapsing Foot Deformity (PCFD). The new PCFD classification could be effective in providing comprehensive information on the deformity. To date, there has been no study reporting intra- and interobserver reliability and the frequency of each class in PCFD classification.

METHODS

This was a single-center, retrospective study conducted from prospectively collected registry data. A consecutive cohort of PCFD patients evaluated from February 2015 to October 2020 was included, consisting of 92 feet in 84 patients. Classification of each patient was made using characteristic clinical and radiographic findings by 3 independent observers. Frequencies of each class and subclass were assessed. Intraobserver and inteobserver reliabilities were analyzed with Cohen kappa and Fleiss kappa, respectively.

RESULTS

Mean sample age was 54.4, 38% was male and 62% were female. 1ABC (25.4%) was the most common subclass, followed by 1AC (8.7%) and 1ABCD (6.9%). Only a small percentage of patients had isolated deformity. Class A was the most frequent component (89.5%), followed by C in 86.2% of the cases. Moderate interobserver reliability (Fleiss kappa = 0.561, P < .001, 95% CI 0.528-0.594) was found for overall classification. Very good intraobserver reliability was found (Cohen kappa = 0.851, P < .001, 95% CI 0.777-0.926).

CONCLUSION

Almost half (49.3%) of patients had a presentation dominantly involving the hindfoot (A) with various combinations of midfoot and/or forefoot deformity (B), (C) with or without subtalar joint involvement (D). The new system may cover all possible combinations of the PCFD, providing a comprehensive description and guiding treatment in a systematic and individualized manner, but this initial study suggests an opportunity to improve overall interobserver reliability.

LEVEL OF EVIDENCE

Level III, retrospective diagnostic study.

Plantar Plating for Medial Naviculocuneiform Arthrodesis in Progressive Collapsing Foot Deformity

Background:

Medial column procedures are commonly used to treat progressive collapsing foot deformity (PCFD) reconstruction. The aim of this research is to present the clinical results of plantar plating for medial naviculocuneiform (NC) arthrodesis when NC joint pathology contributes to medial arch collapse. The authors hypothesized that lag screws with a plantar neutralization plate would result in a satisfactory NC joint fusion rate.

Methods:

A single-surgeon, retrospective case series was performed on patients with flexible PCFD who underwent NC arthrodesis using lag screws and a contoured neutralization plate applied plantarly across the medial NC joint as part of PCFD reconstruction. Thirteen patients (11 females, 2 males; mean age 53.1 [34-62] years) between 2016 and 2019 were identified for inclusion. Mean follow-up was 25.2 ± 12.7 months. Preoperative and postoperative anteroposterior talo–first metatarsal angle, lateral talo–first metatarsal angle, talonavicular coverage angle, and calcaneal pitch were measured. Union was evaluated radiologically. AOFAS midfoot scores were recorded at final follow-up.

Results:

All parameters demonstrated a significant improvement. Fusion was confirmed in 11 of 13 patients (85%) at a mean 5.7 ± 2.1 months. One patient required a revision of their NC fusion because of symptomatic nonunion. There were no cases of symptomatic plantar hardware.

Conclusion:

The results of this small cohort series suggest that lag screw with plantar plate NC arthrodesis yielded generally improved short-term radiographic and clinical outcomes in PCFD patients with medial arch collapse through the NC joint.

Level of Evidence: Level IV, retrospective case series.

Contribution of First-Tarsometatarsal Joint Fusion to Deformity Correction in the Treatment of Adult-Acquired Flatfoot Deformity

Background:

Severe adult-acquired flatfoot deformity (AAFD) is often associated with painful medial column collapse at the naviculocuneiform (NC) joint. However, many surgeons surgically correct the deformity without directly addressing this joint. The purpose of this study was to examine the role of first-tarsometatarsal (TMT) fusion combined with subtalar fusion in correcting deformity at the NC joint.

Methods:

We retrospectively analyzed 40 patients (41 feet) who underwent first-TMT and subtalar (ST) fusion as part of a flatfoot reconstructive procedure. We assessed 6 radiographic parameters both preoperatively and at a minimum of 6 months postoperatively, including talonavicular (TN) coverage angle, lateral talo–first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, hindfoot moment arm, and a newly defined navicular-cuneiform incongruency angle (NCIA). Patient-Reported Outcomes Measurement Information System (PROMIS) clinical outcomes were assessed preoperatively and at a minimum 1-year follow-up.

Results:

The NCIA demonstrated excellent interobserver reliability, with no significant change between pre- and postoperative measurements. All other radiographic parameters, except calcaneal pitch, demonstrated statistically significant improvement postoperatively (P < .01). Overall, patients had statistically significant improvement in all PROMIS domains (P < .01), except for depression. Worsening NC deformity was not associated with worse patient-reported outcomes.

Conclusions:

Our data suggest that when addressing painful collapse of the medial arch in patients with AAFD, fusion of the first-TMT joint in combination with other procedures leads to acceptable radiographic and clinical outcomes. There was no change in deformity at the NC joint in our patient cohort at short-term follow-up, and patients achieved significant improvement in multiple PROMIS domains. Although TMT fusion had no effect on NC deformity, residual or worsening NC deformity did not significantly affect clinical outcomes. In addition, the NCIA was found to be a reliable radiographic parameter to assess NC deformity in the presence of talonavicular and/or first-TMT fusion.

Level of Evidence:

Level III, retrospective comparative study.

Medial Column Biomechanics: Nonsurgical and Surgical Implications

Understanding of medial column biomechanics is paramount to a successful outcome in both conservative and surgical treatment. Dysfunctions of the dynamic stabilizers as well as the static stabilizers of the medial column play a role in pathomechanics. Conservative options for addressing the medial column include custom foot orthotics and bracing. Options for addressing the medial column surgically with the goal to restore a stable tripod configuration, include first tarsometatarsal joint arthrodesis, opening plantarflexory medial cuneiform osteotomy, and naviculocuneiform arthrodesis.

Naviculocuneiform Arthroscopy

Surgical interventions at the naviculocuneiform joint are not uncommon to deal with various pathologies of the joint and correction of different foot deformities. To minimize the soft tissue dissection, naviculocuneiform arthroscopy has been described. The purpose of this Technical Note is to report the details of this arthroscopic approach.