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Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Charcot-Marie-Tooth (CMT) disease is the most common cause of cavus foot. The complex deformities in cavovarus feet of CMT disease are difficult to evaluate. The bone axes of CMT may be difficult to calculate by conventional weightbearing computed tomography (WBCT). For this reason, 3D automated measurements have been used to assess complex anatomy. The aim of this study was to quantitatively assess deformity correction following joint sparing CMT cavovarus reconstruction surgery. This is the first study investigating preoperative and postoperative WBCT findings in CMT feet using semi-automated 3D measurements. Methods: The study was approved by our institutional review board and informed consent was obtained from all patients. Joint sparing CMT surgery was performed with multiple soft tissue releases and bony procedures. Among the 170 cases from May 2021 to May 2023, twenty-nine CMT patients who had both pre- and postoperative WBCTs were retrospectively analyzed. 3D measurements of WBCT were performed using semi-automated software (Bonelogic 2.1, Disior) to investigate changes in sagittal, axial, and coronal parameters. Pre- and postoperative data was compared using a Wilcoxon signed-ranks test and these data were also compared with normative data using a Welch's t-test. Correlation among these sagittal, axial, and coronal parameters were analyzed using Spearman’s rank correlation coefficient test. Results: The sagittal, axial, and coronal malalignment of the hindfoot, and the sagittal and axial malalignment of the forefoot was significantly improved after corrective surgery (P < .05). Sagittal Meary’s angle (from 14.8 degrees to 0.1 degrees), axial talonavicular angle (TNA, from 3.6 degrees to 19.2 degrees), and coronal hindfoot alignment (from 11.0 degrees to -11.1 degrees) showed significant changes postoperatively (P < .001). Hindfoot, forefoot sagittal and forefoot axial parameters reached comparable outcomes compared to normative value (P > .05). Regarding amount of correction, Spearman’s correlation demonstrated that axial Meary’s angle and TNA were most strongly related to improvement in sagittal Meary’s angle and coronal hindfoot alignment. Conclusion: Preoperative and postoperative WBCT measurements demonstrated that joint sparing CMT cavovarus reconstruction significantly improved sagittal, axial, and coronal deformities of CMT, and sagittal Meary’s angle was restored toward normative values. Apparent axial plane correction, the majority of which occurred at the talonavicular joint, had the strongest correlation with deformity correction in multiple planes. This suggests that soft tissue releases and correction of the talonavicular joint may be a key component of a CMT cavovarus foot correction. Figure. (A) CMT surgery with soft tissue releases and bony procedures, (B) Pre- and postoperative radiographic results, and gross photos of the operated right foot of a 17-year-old male patient.

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: This is the first study to compare weight-bearing radiographs to weight-bearing computed tomography (WBCT) in the preoperative evaluation of Charcot-Marie-Tooth patients. This comparison is important as WBCT is not widely available, and its current role in preoperative planning remains unclear. Methods: We performed a retrospective review of CMT patients with cavovarus deformity with weight-bearing radiographs (WBR) and WBCT. Lateral talus-first metatarsal angle, calcaneal pitch, anteroposterior (AP) talus-first metatarsal angle, and talonavicular coverage angle were measured on WBR on WBCT. Intraclass correlation coefficients (ICC) between raters and imaging modalities were calculated. ICC values were interpreted as follows: ICC < 0.50 = poor agreement; 0.50 < ICC < 0.75 = moderate agreement; 0.75 < ICC < 0.90 = good agreement; and ICC > 0.90 = excellent agreement. Results: 38 feet from 34 patients, 21 female, 13 male, with an average age of 42 years old (range 19-72) were included. Interrater reliability was good or excellent for all measures except talonavicular coverage angle, which was moderate for both WBR and WBCT (Table 1A). Inter-method reliability was good for all measures except talonavicular coverage angle which was moderate (Table 1B). Conclusion: In the 38 CMT feet assessed in this study, we found good agreement between WBR and WBCT measurements, except for talonavicular coverage angle. For surgeons without access to WBCT, these results may ease concern regarding surgical planning using weight-bearing radiographs alone.

Category: Midfoot/Forefoot; Other Introduction/Purpose: The typical cavovarus deformity seen in patients with Charcot-Marie-Tooth involves plantarflexion of the first ray. Surgical correction often includes a dorsiflexion osteotomy at the first metatarsal base or medial cuneiform. The exact apex of the deformity has never been proven, although it is presumed to be within the medial cuneiform. The aim of this study was to utilize weight-bearing computed tomography (WBCT) to localize and quantify the plantarflexion deformity in CMT patients. Methods: WBCTs of 16 CMT patients with lateral Meary’s angle >20 degrees were compared to controls utilizing semi-automated analysis software (Disior Bonelogic). Due to the complex deformity seen in CMT patients, a local coordinate system based on the first metatarsal was used. The tarsometatarsal angle was subdivided into components (cuneiform-cuneiform joint normal, tarsometatarsal joint and metatarsal-metatarsal joint normal) and compared between CMT and controls (Figure 1A). CMT patient’s first, second and third rays were also compared. Means were compared with a 2-sample t test (p

Category: Hindfoot Introduction/Purpose: Haglund’s syndrome involves a prominent posterior superior prominence of the calcaneus, in conjunction with pain caused by local inflammation. Nonoperative management includes orthotic inserts, immobilization, shoe modification and physical therapy. If non-operative management fails, surgical management with calcaneoplasty is often needed. No study has assessed Achilles tendon pull-out strength after a calcaneoplasty for Haglund’s syndrome. The purpose of this study was to investigate those changes in a cadaveric model and provide objective data upon which to base postoperative recovery. Methods: 8 matched pairs of cadaveric specimens (mid-tibia to toes) were divided into two cohorts. The matched pairs compared Achilles pull-out strength between intact and open calcaneoplasty specimens. Prior to testing, BMD was determined and lateral X-ray images were obtained before and after surgery to quantify bone removal. The distal aspect of each calcaneus was potted and held at a 20 degree angle. The Achilles tendon was secured in a freeze-clamp, which was attached to a mechanical testing system. Specimens were then loaded to failure. Outcome measures include: Height of bony resection, angle of bone resection, load to failure, and mode of failure. Results: Specimens with open calcaneoplasty had a 45% reduction in strength (failure load: 742 N) compared to their intact counterpart (1341 N), p

Category: Hindfoot Introduction/Purpose: The risk of Achilles avulsion is the limiting factor in return to full weight bearing and early activity following calcaneoplasty for Haglund’s syndrome. The most commonly performed surgical procedure is an open calcaneoplasty through a posterior approach. Another option is an endoscopic decompression, which theoretically causes less disruption of the Achilles insertion, and allows a more rapid return to full weight bearing and activity. Despite this potential benefit no study has assessed the difference in Achilles tendon pull-out strength after open versus endoscopic techniques. The purpose of this study was to investigate those changes in a cadaveric model and provide objective data upon which to base postoperative recovery. Methods: Six matched pairs of cadaveric specimens(mid-tibia to toes) were randomly divided into two surgical groups.Group#1 was treated with an endoscopic decompression under fluoroscopic guidance using a 4 mm burr.Group#2 was treated with a traditional calcaneoplasty through a posterior approach using a microsaggital saw.The Achilles was repaired back to the calcaneus with two nonsabsorbable suture anchors in Group #2.Fouroscopic guidance was used to exactly match the amount of bone removed from each matched pair.Pre and post procedure true lateral x-rays were obtained in both groups to quantify bone loss.These radiographic images were imported into Matlab computational software(MathWorks, Inc., Natick, MA) for digital analysis. The distal aspect of each calcaneus was potted and held at a 20 degree angle.The Achilles tendon was secured in a freeze-clamp, which was attached to a mechanical testing system. Specimens were then loaded to failure. Outcome measures include: Height of bony resection, angle of bone resection and load to failure. Results: To date our results show significantly higher pullout forces in specimens that had an endoscopic calcaneoplasty (average failure load: 1368 ±445 N) compared to those that received an open surgical procedure (450±184 N), p

Category: Hindfoot Introduction/Purpose: There are multiple surgical osteotomies described for the correction of heel varus. An adequately powered clinical comparison of these osteotomies has not been published. In this study we used 18 identical 3D prints of a patient with heel varus to compare the surgical correction obtained with a Dwyer, oblique or Z osteotomy. The adequately powered statistical results of this study quantify the unique advantages and limitations of these osteotomies. Methods: A CT scan of a patient with heel varus (16 degrees) from Charcot-Marie-Tooth disease was selected for 3D modeling. Eighteen identical 3D prints were created of an anatomical construct of the talus, calcaneus and cuboid. Coordinate frames were added to the talus and calcaneus to evaluate rotation. Six of the prints were CT scanned to establish baseline data measurements (Uncut Control Group). All 18 prints were then divided into 3 groups of 6 models each. A custom jig was used to precisely and accurately replicate a different osteotomy in each group( Dwyer, oblique or Z). A 1 cm wedge was removed from each osteotomy. Following the simulated surgeries, all 18 models were CT scanned using the same parameters as had been used for the uncut models. Anatomic and coordinate measurements were calculated using multiplanar reconstruction image processing. Coordinate measurements were established as the rotation of the calcaneal coordinate frame with respect to the talar coordinate frame. Results: A standard 1-way analysis (ANOVA) was performed on the initial data. Additionally, a Tukey Studentized Range test was run using the raw data to compare the uncut model, Dwyer, oblique and Z osteotomies for all variables that showed statistically significant differences using the ANOVA. Coronal angle correction (Figure 1): The overall ANOVA test is significant (p < 0.001). Tukey post-hoc comparisons demonstrate that Z is significantly different from Oblique (mean difference = 8.8; 95pct CI [5.5,12.0]; p < 0.001) and Dwyer (mean difference = 10.4; 95pct CI [7.1, 13.6]; p < 0.001), but Oblique and Dwyer are not significantly different from each other (mean difference = 1.6; 95 pct CI [-1.6, 4.9]; p=0.422). Calcaneal shortening (Figure 2): The overall ANOVA test is significant (p < 0.001). All group comparisons are significant except for the Z vs Uncut (p=0.919). Lateral translation (Figure 3): The overall ANOVA test is significant (p < 0.001). All group comparisons are statistically significant from one another. Conclusion: The Z osteotomy provided significantly more correction in the coronal plane (varus/valgus), with no significant shortening of the calcaneus, compared to the Dwyer and oblique osteotomies. The Z osteotomy, however, produced much less correction than anticipated, with only 3 degrees of final heel valgus. The Dwyer and Oblique osteotomies remained in varus. None of the osteotomies provided more than 6mm lateral translation of the tuberosity. These results have significant application to the appropriate choice of a calcaneal osteotomy for heel varus.