Evans Calcaneal Osteotomy: Assessment of Multiplanar Correction

Three-Dimensional Distance Mapping to Identify Safe Zones for Lateral Column Lengthening

BACKGROUND

Evans (E-LCL) and Hintermann LCL (H-LCL) lateral column lengthening osteotomies are standard surgical solutions for flexible, progressive collapsing feet. E-LCL is performed between the anterior and middle facets and endangers specific os calcis subtalar joint (OCST) subtypes without distinct facets. H-LCL is oriented between the posterior and middle facets and should be suitable for all OCSTs. Both osteotomies are associated with increased subtalar osteoarthritis, indicating iatrogenic damage. Distance mapping (DM) enables visualization of the relative distance between 2 articular surfaces represented by color patterns. This study aims to measure the safe zones for LCL using 3-dimensional (3D) models and DM; we hypothesize that it could be measured with high reproducibility.

METHODS

Two raters categorized 200 feet across 134 patients into OCSTs based on the Bruckner classification. Four angles were measured independently. The proximal and distal extents of the posterior safe zone (PSZ) angles were determined for H-LCL osteotomies; similarly, the proximal and distal extents of the anterior safe zone (ASZ) angles were identified for E-LCL osteotomies. Consequently, the surface available for safe osteotomies were calculated. An interclass correlation was used to assess the agreement between the 2 raters. Additionally, analysis of variance and Mann-Whitney U test were used to compare the safe zones between OCSTs.

RESULTS

The mean proximal and distal extents of the PSZ angles were 68 ± 7 and 75 ± 5 degrees from a line parallel to the lateral border of the calcaneus, respectively, and the proximal and distal extent of the ASZ angles were 89 ± 6 and 95 ± 5 degrees, respectively. There were no statistically significant differences between the OCSTs. Two raters measured the angles with good to excellent interrater and intrarater agreement. In 18 cases, we were unable to plan for H-LCL or E-LCL osteotomies.

CONCLUSION

Distance mapping could be used to measure the safe zone, tailor a preoperative plan, and potentially reduce the risk for iatrogenic damage in LCL. 3D models and DM can increase the reliability of preoperative plans in bones with complex 3D structures.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Tibialis anterior rerouting combined with calcaneal lengthening osteotomy as a single-stage reconstruction of symptomatic flexible flatfoot in children and adolescents

BACKGROUND

Symptomatic flexible flatfoot in children and adolescents should be surgically managed only if conservative measures have failed. The aim of this study was to assess functional and radiological results of tibialis anterior rerouting combined with calcaneal lengthening osteotomy as s single-stage reconstruction of symptomatic flexible flatfoot.

METHODS

The current study was a prospective study of patients with symptomatic flexible flatfoot treated by single-stage reconstruction in the form of tibialis anterior tendon rerouting combined with calcaneal lengthening osteotomy. The American Orthopaedic Foot and Ankle Society score (AOFAS) was utilized to evaluate the functional outcomes. The evaluated radiological parameters included the standing anteroposterior (AP) and lateral talo-first metatarsal angle, talar head coverage angle, and calcaneal pitch angle.

RESULTS

 The current study included 16 patients (28 feet) with a mean age of 11.6 ± 2.1 years. There was a statistically significant improvement in the mean AOFAS score from 51.6 ± 5.5 preoperatively to 85.3 ± 10.2 at final follow-up. Postoperatively, there was a statistically significant reduction in the mean AP talar head coverage angle from 13.6 ± 4.4° to 3.9 ± 3°, the mean AP talo-first metatarsal angle from 16.9 ± 4.4° to 4.5 ± 3.6°, and the mean lateral talo-first metatarsal angle from 19.2 ± 4.9° to 4.6 ± 3.2°, P < 0.001. Additionally, the mean calcaneal pitch angle increased significantly from 9.6 ± 1.9° to 23.8 ± 4.8°, P < 0.001. Superficial wound infection occurred in three feet and was treated adequately by dressing and antibiotics.

CONCLUSION

 Symptomatic flexible flatfoot in children and adolescents can be treated with combined lateral column lengthening and tibialis anterior rerouting with satisfactory radiological and clinical outcomes. Level of evidence Level IV.

Classification of the Os Calcis Subtalar Morphology in Symptomatic Flexible Pediatric Pes Planus Deformity Using Weightbearing CT and Distance Mapping

BACKGROUND

The etiology of symptomatic pediatric pes planus (PP) deformity is unclear. Reduced os calcis subtalar joint (OCST) anterior facet morphology has been suggested to result in less support to the talar head and a higher propensity to develop PP deformity. Weightbearing computed tomography (WBCT) and distance mapping (DM) offer new opportunities to investigate PP deformity in general and the OCST specifically. The purpose of this study is to investigate the OCST morphology using DM and to classify PP subtalar subtypes with DM using Bruckner's A-D classification system.

METHODS

Forty feet in 25 patients in a national referral center were evaluated for symptomatic PP deformity that failed nonoperative treatment. A WBCT scan was performed as part of the preoperative evaluation. Visualization of the distance distribution between the articulating surfaces of the subtalar joint was based on a DM technique. Intra- and interobserver agreement of the subtalar morphology was assessed using Bruckner's classification system.

RESULTS

The mean age was 10.7 ± 1.4 years. The following mean ± SD and median ± ranges were semiautomatically measured for this group: Meary angle -21 ± 8, calcaneal inclination 15 ± 4 degrees, talar coverage angle 39 (range 32.6-49) degrees, and hindfoot moment-arm 16 ± 5 mm. Classifying subtalar morphology using DM yielded an excellent intra- and interobserver agreement. The individual percentages of each individual subtype were calculated: type A 5%, type B 48%, type C 4%, and type D in 44%.

CONCLUSION

This study demonstrated excellent intraobserver and interobserver agreement in classifying the OCST using DM. A higher prevalence of types B and D was observed compared to types A and C in this PP cohort.

LEVEL OF EVIDENCE

Level III, retrospective study.

Lateral column lengthening (LCL) using a rectangular shape graft for managing symptomatic flexible flatfoot showed acceptable early functional and radiological outcomes

PURPOSE

We aimed to report the results of performing lateral column lengthening (LCL) using a rectangular-shaped graft to correct the flat foot deformity.

METHODS

A total of 28 feet of 19 patients (10 males, 9 females) having an average age of 10 ± 3.2 years who were unresponsive to conservative management underwent flat foot deformity correction through LCL procedure supplemented with rectangular-shaped graft harvested from the fibula. Functional assessment was performed according to the American Orthopedic Foot and Ankle Society (AOFAS) scale. The radiographic assessment consisted of four parameters, Meary's angle in both anteroposterior (AP) and lateral (Lat.) views, calcaneal inclination angle (CIA), and calcaneocuboid angle (CCA).

RESULTS

After an average of 30.2 ± 8.1 months, the AOFAS improved significantly from 46.7 ± 10.2 preoperatively to 86.7 ± 9.5 at the last follow up (P < 0.05). All the osteotomies showed healing at an average of 10.3 ± 2.7 weeks. All the radiological parameters showed significant improvement at the last follow up compared to the preoperative measurements, CIA from 6.3 ± 2.8-19.3 ± 3.5, Lat. Meary's angle from 19.3 ± 4.9-5.8 ± 2.5, AP Meary's Angle from 19.3 ± 5.8-6.1 ± 3.1, and CCA from 23.9 ± 8.2-6.8 ± 4.5, (P < 0.05). No pain at the site of the fibular osteotomy was reported in any of the patients.

CONCLUSION

Lateral column lengthening using a rectangular graft effectively restores bony alignment with good radiological and clinical results, high patient satisfaction, and acceptable complications.