Biomechanical effects of Evans versus Hintermann osteotomy for treating adult acquired flatfoot deformity: a patient-specific finite element investigation

BACKGROUND

Evans and Hintermann lateral column lengthening (LCL) procedures are both widely used to correct adult acquired flatfoot deformity (AAFD), and have both shown good clinical results. The aim of this study was to compare these two procedures in terms of corrective ability and biomechanics influence on the Chopart and subtalar joints through finite element (FE) analysis.

METHODS

Twelve patient-specific FE models were established and validated. The Hintermann osteotomy was performed between the medial and posterior facets of the subtalar joint; while, the Evans osteotomy was performed on the anterior neck of the calcaneus around 10 mm from the calcaneocuboid joint surface. In each procedure, a triangular wedge of varying size was inserted at the lateral edge. The two procedures were then compared based on the measured strains of superomedial calcaneonavicular ligaments and planter facia, the talus-first metatarsal angle, and the contact characteristics of talonavicular, calcaneocuboid and subtalar joints.

RESULTS

The Hintermann procedure achieved a greater correction of the talus-first metatarsal angle than Evans when using grafts of the same size, indicating that Hintermann had stronger corrective ability. However, its distributions of von-Mises stress in the subtalar, talonavicular and calcaneocuboid joints were less homogeneous than those of Evans. In addition, the strains of superomedial calcaneonavicular ligaments and planter facia of Hintermann were also greater than those of Evans, but both generally within the safe range (less than 6%).

CONCLUSION

This FE analysis study indicates that both Evans and Hintermann procedures have good corrective ability for AAFD. Compared to Evans, Hintermann procedure can provide a stronger corrective effect while causing greater disturbance to the biomechanics of Chopart joints, which may be an important mechanism of arthritis. Nevertheless, it yields a better protection to the subtalar joint than Evans osteotomy.

CLINICAL RELEVANCE

Both Evans and Hintermann LCL surgeries have a considerable impact on adjacent joints and ligament tissues. Such effects alongside the overcorrection problem should be cautiously considered when choosing the specific surgical method.

LEVEL OF EVIDENCE

Level III, case-control study.

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.

Union in Lateral Column Lengthening by Plate Fixation Without Bone Graft in Flexible Flatfoot: A Case Series

Purpose

This study's goal was to evaluate the outcomes of lateral column lengthening by plate fixation without bone graft in the management of symptomatic flexible flatfoot.

Methods

A prospective randomized trial study included 30 feet (27 patients) and was performed from March 2017 to December 2019. Functional and radiological evaluations were done pre-operative and at the final post-operative follow-up. The functional assessment was done using the American Orthopaedic Foot and Ankle Society (AOFAS) score.

Results

The mean follow-up was 16.5 ± 3.027 months. The mean age of patients was 22.6 ± 6.29 years. All cases showed union ranging from 8 to 12 weeks, with a mean of 10 ± 1.88 weeks. The mean AOFAS score improved from 51.6 ± 6.75 to 92.2 ± 6.21. The mean anteroposterior (AP) talo-first metatarsal angle improved from 25.3° ± 8.31° to 3.4° ± 5.10°. The mean anteroposterior (AP) talo-navicular coverage improved from 22.10° ± 4.28° to 2.3° ± 3.46°. The mean Lateral talo-first metatarsal angle improved from 18.6° ± 4.79° to 3.3° ± 3.16°. The calcaneal pitch angle improved from 9.6° ± 4.14° to 15.1° ± 4.43°. The mean lateral talo-calcaneal angle improved from 45.7° ± 3.77° to 37.5° ± 3.47°.

Conclusion

Using an interposition wedge plate for LCL without bone graft leads to a high union rate, maintains the correction, and avoids possible complications of autografts and allografts.

Opening Cuboid Wedge Osteotomy (Zoom Osteotomy) for Triplanar Correction of Flexible Pes Planovalgus Deformities

Surgical correction of flexible pes planovalgus often involves reestablishing the length of the lateral column. This is a review of a cohort of patients who underwent an opening cuboid osteotomy with interpositional graft for triplanar correction of flexible pes planovalgus. The medical records of 35 patients involving 51 feet were reviewed. All patients were treated with an opening wedge osteotomy of the cuboid in combination with adjunctive procedures as needed for correction of the pes planovalgus deformity. Radiographs were obtained before and a minimum of 12 months after surgery. Preoperative and postoperative cuboid abduction and Meary's (lateral talometatarsal) angles were measured using the radiographs, and adjunctive procedures and complications were recorded. Mean follow-up was 46 (range, 12-85) months. The mean cuboid abduction angle improved from 20.3° (range, 8°-31°) to 6.6° (range, 0°-15°), and the mean Meary's angle improved from 10.5° (range, 0°-25°) to 2° (range, -3° to 15°). All patients also underwent adjunctive procedures at the time of cuboid osteotomy. In the 51 feet treated, there were 3 (6%) complications, including wound dehiscence, neuritis, and deep vein thrombosis. There were no recurrences. Triplanar correction of flexible pes planovalgus can be performed safely and successfully with an opening cuboid osteotomy as an alternative to the Evans Osteotomy.

Does the stabilization of the calcaneocuboid joint with Steinmann pin in Evans osteotomy affect its incidence of arthritis?

PURPOSE

This study aims to determine the effect of retaining a Steinmann pin in the calcaneocuboid joint on its rates of arthritis following Evans calcaneal osteotomy lengthening procedure. The study hypothesized that leaving the pin across the calcaneocuboid joint post-operatively would lead to higher rates of arthritis.

METHODS

This is a retrospective review of patients under 18 years of age who underwent Evans osteotomy at our hospital from January 2015 to May 2020. The Patients were stratified into 2 groups: Group 1 (pin was left post-operatively across the joint and removed on follow-up) and Group 2 (pin was removed during surgery). Demographic data were recorded, including age, sex, and body mass index. Calcaneocuboid arthritis was determined by radiographic imaging at least one-year follow-up. Time to pin removal, size of the pin and graft, and subluxation were analyzed as possible risk factors for arthritis. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were estimated.

RESULTS

39 patients were included in the study: 24 patients had the pin removed post-operatively, and 15 had the pin removed intra-operatively. There were no significant differences between the 2 groups regarding body mass index, age, sex, or laterality. Calcaneocuboid arthritis rates were significantly higher in the Group 1 than Group 2 (12(50%) vs. 2(13.3%), respectively; p = 0.02). On multivariate regression, both age (OR, 1.305 [95%CI: 1.009-1.696]; p = 0.044) and leaving the pin in the joint postoperatively (OR, 7.661 [95%CI: 1.208-48.570]; p = 0.031) were found as risk factors for arthritis at follow-up. The mean time to pin removal, the size of the pin, and the size of the graft were not found to be significant predictors of arthritis (p > 0.05).

CONCLUSIONS

This study shows that leaving the Steinmann pin in the calcaneocuboid joint in children post-operatively is associated with an increased risk of developing early radiographic signs of calcaneocuboid joint arthritis.

I am Afraid of Lateral Column Lengthening. Should I Be?

Lateral column lengthening has long been used in conjunction with other soft tissue and bony procedures to correct the midforefoot abduction seen in class B progressive collapsing foot deformity. The effectiveness of this osteotomy to restore the physiologic shape of the foot has been used by foot and ankle surgeons around the world to provide functional improvement for patients suffering from this disease. The overall low complication rates, low nonunion rates, and improved radiographic and functional outcomes provided by lateral column lengthening make this a valuable option for the treatment of class B progressive collapsing foot deformity.

Lateral Column Lengthening Revisited: A Simple Intraoperative Approach to Ensure a True Extra-Articular Osteotomy

Lateral column lengthening is a common method for treatment of patients with symptomatic flat feet. Although variations of the technique have been described by many authors, there is a lack of agreement about the exact location of the osteotomy. Most authors tried to find the interval between the anterior and middle talocalcaneal facets but did not offer a reproducible method to achieve this purpose. The use of a plantarflexion anteroposterior view of the foot provides better visualization of the anatomic landmarks and helps to precisely perform the osteotomy anterior to the sustentaculum tali, with protection of the anterior and middle talocalcaneal facets.

Outcomes of Evans Versus Hintermann Calcaneal Lengthening Osteotomy for Flexible Flatfoot

BACKGROUND

Evans (E) and Hintermann (H) lateral lengthening calcaneal osteotomies (LLCOTs) are commonly used to correct flexible flatfoot deformities. Both methods are well accepted and produce good clinical results. The aim of this study was to compare the postoperative outcomes of both osteotomies.

METHODS

We retrospectively examined 53 patients with flatfoot deformities, who received surgery between October 2008 and March 2014. Seventeen E-LLCOT and 36 H-LLCOT procedures were performed during this time period, with a mean follow-up of 67.7 ± 20.6 and 40 ± 12.9 months, respectively. Data were collected using clinical and radiological examination, as well as clinical scores (Foot and Ankle Outcome Score [FAOS], University of California at Los Angeles [UCLA] activity score, numerical rating scale [NRS], and the Short-Form 36-item Health Survey [SF-36]) during regular follow-up.

RESULTS

For both groups of patients, the FAOS score, pain-NRS, and SF-36 improved significantly following surgery ( P < .05). The talus-second metatarsal angle, talonavicular coverage, and naviculocuneiform overlap showed significant correction ( P < .05). Postoperatively, radiographic degenerative changes were detected in the calcaneocuboid (CC) and subtalar joint in both groups of patients: 41% and 18% after E-LLCOT compared with 25% and 14% after H-LLCOT, although these changes did not have any clinical relevance ( P < .05). No secondary arthrodesis was necessary. There were no significant differences in the clinical or radiological outcome parameters when compared between the 2 groups.

CONCLUSION

Both surgical techniques resulted in a significant improvement of clinical outcome scores and led to good radiological correction of flatfoot deformities. It appears that the CC joint develops less degenerative changes following the H-LLCOT procedure.

LEVEL OF EVIDENCE

Level III, comparative series.

Long-Term Outcomes of Corrective Osteotomies Using Porous Titanium Wedges for Flexible Flatfoot Deformity Correction

Common corrective osteotomies used in flexible flatfoot deformity reconstruction include Cotton and Evans osteotomies, which require structural graft to maintain correction. Auto-, allo-, and xenografts are associated with a number of limitations, including disease transmission, rejection, donor site morbidity, technical challenges related to graft fashioning, and graft resorption. Porous titanium is a synthetic substance designed to address these flaws; however, few studies have been reported on the efficacy, safety, and long-term outcomes. A multicenter retrospective cohort of 63 consecutive preconfigured porous titanium wedges (PTWs) used in flexible flatfoot reconstructions from June 1, 2009 to June 30, 2015 was evaluated. The primary outcome measure was the pre- to postdeformity correction efficacy. The secondary outcomes included maintenance of correction at a minimum follow-up point of 12 months, complications, graft incorporation, and graft safety profile. Multivariate linear regression found a statistically significant improvement in all radiographic parameters from preoperatively to the final weightbearing radiographs (calcaneocuboid 18.850 ± 4.020 SE, p < .0001; Kite's, 7.810 ± 3.660 SE, p = .04; Meary's 13.910 ± 3.100 SE, p = .0001; calcaneal inclination, 5.550 ± 2.140 SE, p = .015). When restricted to patients with >4 years of follow-up data, maintenance of correction appeared robust in all 4 measurements, demonstrating a lack of bone or graft resorption. No patients were lost to follow-up, no major complications or implant explantation or migration occurred, and all implants were incorporated. Minor complications included hardware pain from plates over grafts (8%), 1 case of scar neuritis, and a 5% table incidence of transfer pain associated with the PTWs. These results support the use of PTWs for safety and degree and maintenance of correction in flatfoot reconstruction.

Surgical Management of Stage 2 Adult and Pediatric Acquired Flatfoot Without Tendon Transfer or Arthrodesis: A Retrospective Study

Posterior tibial tendon dysfunction (PTTD) is a common pathology of the foot and ankle. Numerous techniques are available to reconstruct the flatfoot. Fusions and tendon transfers are popular methods; however, a wide range of complications have been associated with these procedures. The objective of the present study was to demonstrate the outcomes of reconstructive surgery for flatfoot correction without tendon transfer or arthrodesis. We performed a retrospective study of 43 patients and 56 feet who had undergone flatfoot reconstructive surgery from November 2011 to June 2016, with a mean follow-up period of 60 weeks (range 12 to 60 months). Each patient demonstrated a stage 2 flatfoot deformity classified using the Johnson and Strom classification. Depending on the patient's deformity, the procedures consisted of different variations of gastrocnemius recession, medial displacement calcaneal osteotomy, Evans osteotomy, and Cotton osteotomy. Six different preoperative and postoperative angles were radiographically measured on each foot studied. In all cases, the differences in the preoperative versus postoperative measurements were statistically significant (p < .003). We believe the foot and ankle surgeon can correct flatfoot deformity with the use of extraarticular procedures and create a plantigrade functional foot without fusion or tendon transfer.

Comparison of Anatomic Structures at Risk With 2 Lateral Lengthening Calcaneal Osteotomies

BACKGROUND:

Lateral lengthening calcaneal osteotomies (LLCOT) are commonly used to treat flexible pes planovalgus deformity. Different operative techniques have been described. The aim of this study was to examine which anatomic structures were affected by 2 different osteotomy techniques.

METHODS:

Two experienced foot and ankle surgeons each performed an Evans (E)- or Hintermann (H) osteotomy on 7 cadaver feet. The mean age of the donors was 80.4 ± 4.4 years. Eight left and 6 right feet were prepared. Previously identified structures at risk were prepared and evaluated.

RESULTS:

After H-LLCOT, there was no damage of the peroneus longus tendon, whereas after E-LLCOT, damage was noted in 1 case (14.3%). The peroneus brevis tendon was once cut after H-LLCOT and eroded after E-LLCOT. In one cadaver, the sural nerve was partially damaged after H-LLCOT but in no case after E-LLOCT. The calcaneal anterior and medial articular facets were intact after H-LLCOT in 100% and 85.7% and after E-LLCOT in 42.9% and 71.4%, respectively. The posterior articular surface was not affected in any cadaver.

CONCLUSION:

Anatomic structures can be damaged after both osteotomies. With the Hintermann osteotomy, the calcaneal anterior and medial articular surface can be protected to a larger extent than with the Evans osteotomy.

CLINICAL RELEVANCE:

The Hintermann osteotomy seems to be superior, regarding damage of the articular surfaces of the subtalar joint. These findings have to be correlated with biomechanical and clinical studies before a final recommendation can be given, which osteotomy is superior.

Comparative Outcomes Between Step-Cut Lengthening Calcaneal Osteotomy vs Traditional Evans Osteotomy for Stage IIB Adult-Acquired Flatfoot Deformity

BACKGROUND

The forefoot abduction component of the flexible adult-acquired flatfoot can be addressed with lengthening of the anterior process of the calcaneus. We hypothesized that the step-cut lengthening calcaneal osteotomy (SLCO) would decrease the incidence of nonunion, lead to improvement in clinical outcome scores, and have a faster time to healing compared with the traditional Evans osteotomy.

METHODS

We retrospectively reviewed 111 patients (143 total feet: 65 Evans, 78 SLCO) undergoing stage IIB reconstruction followed clinically for at least 2 years. Preoperative and postoperative radiographs were analyzed for the amount of deformity correction. Computed tomography (CT) was used to analyze osteotomy healing. The Foot and Ankle Outcome Scores (FAOS) and lateral pain surveys were used to assess clinical outcomes. Mann-Whitney U tests were used to assess nonnormally distributed data while χ² and Fisher exact tests were used to analyze categorical variables (α = 0.05 significant).

RESULTS

The Evans group used a larger graft size ( P < .001) and returned more often for hardware removal ( P = .038) than the SLCO group. SLCO union occurred at a mean of 8.77 weeks ( P < .001), which was significantly lower compared with the Evans group ( P = .02). The SLCO group also had fewer nonunions ( P = .016). FAOS scores improved equivalently between the 2 groups. Lateral column pain, ability to exercise, and ambulation distance were similar between groups.

CONCLUSION

Following SLCO, patients had faster healing times and fewer nonunions, similar outcomes scores, and equivalent correction of deformity. SLCO is a viable technique for lateral column lengthening.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Evans Osteotomy Complications

In 1975, Evans published an article describing the surgical management of the "calcaneo-valgus deformity," pointing out that the deformity was due to relative shortening of the lateral column of the foot. Correction involved "equalizing" both columns by performing an osteotomy in the neck of the calcaneus 1.5 cm from the calcaneocuboid joint, where a trapezoidal wedge of tricortical bone was placed. Although it was considered a success, there were complications, including sural nerve injury, surgical wound dehiscence, undercorrection, and graft subsidence. The osteotomy grew in popularity. Indications extended to other forms of flatfoot with a low incidence of complications.

Double calcaneal osteotomy with percutaneous Steinmann pin fixation as part of treatment for flexible flatfoot deformity: a review of consecutive cases highlighting our experience with pin fixation

Surgical correction of flexible flatfoot deformity and posterior tibial tendon dysfunction has been extensively reported in published studies. When appropriate, calcaneal osteotomies for flatfoot correction have been a favorite of foot and ankle surgeons because of the corrective power achieved without the need to fuse any rearfoot joints. The medial displacement calcaneal osteotomy and Evans calcaneal osteotomy, together termed the double calcaneal osteotomy, have been reported several times by various investigators with a wide variety of fixation options. We undertook an institutional review board-approved retrospective review of 9 consecutive patients (11 feet), who had undergone double calcaneal osteotomy with 2 percutaneous Steinmann pin fixation for the correction of flexible flatfoot deformity, with or without posterior tibial tendon dysfunction. All patients had radiographic evidence of bone healing of the posterior calcaneal osteotomy and incorporation of the Evans osteotomy bone graft at 6 weeks and demonstrated clinical healing at 6 weeks. All patients had 2 percutaneous Steinmann pins placed through both osteotomies, and these were removed an average of 6 weeks postoperatively. No patient developed pin site complications. The only complication noted was sural neuritis, which was likely incision related. No patients had delayed union or nonunion, and we did not identify any graft shifting postoperatively. The present retrospective series highlights our experience with 2 percutaneous Steinmann pin fixation, demonstrating equal or better results than many previous published fixation methods for double calcaneal osteotomy. It is cost-effective and minimizes the potential risk of iatrogenic Achilles pathologic features associated with screw fixation.