Assessing the coronal plane deformity in Charcot Marie Tooth Cavovarus feet using automated 3D measurements

Osseous morphology differences in the foot and ankle associated with Charcot-Marie-Tooth disease

Charcot-Marie-Tooth (CMT) disease is a genetic, progressive peripheral nerve disease that commonly manifests in a cavovarus foot deformity. Previously, this foot deformity has been believed to be an alignment change in the foot, but recent research has shown that there are bone morphology differences in individuals with CMT. Differences in bone morphology have been identified in the calcaneus, talus, and medial cuneiform, but have not been consistently analyzed throughout the foot or studied in relation to different genetic subtypes of CMT. This study is a retrospective, cross-sectional analysis of bone morphology in CMT using weight-bearing computed tomography and statistical shape modeling. This analysis identified bone morphology differences between CMT and control groups throughout the hindfoot, midfoot, and forefoot. Bone morphology differences were also present between the 2 primary disease subtypes throughout the foot. Key morphologic findings include the altered shape of the subtalar articular surfaces on the talus, bending of the metatarsals, variation in navicular process morphology, and differences between subtypes in the talus, medial cuneiform, and medial metatarsals. There are several possible theoretical mechanisms for this osseous deformation, including bone remodeling in response to altered loading from alignment change or from decreased musculotendinous forces, but the patterns of morphological variation seen in these data cannot be fully explained by these mechanisms, suggesting that there may be an interaction between the neuronal disease and bone remodeling. Future work is necessary to characterize the progression of bony deformity throughout development and to correlate bone shape with function, gait, muscle morphology and strength to elucidate the mechanism of osseous morphology change in varying subtypes of CMT.

Talar Morphology of Charcot-Marie-Tooth Patients With Cavovarus Feet

BACKGROUND

Charcot-Marie-Tooth disease (CMT), a common inherited neurologic disorder, significantly impacts the morphology of foot bones, particularly the talus. The disease has been classified into types based on specific mutations, with the most common being CMT type 1 (CMT1; demyelinating) and CMT type 2 (CMT2; axonal). However, the specific osseous morphologic variations in CMT patients and their major genetic subgroups remain insufficiently understood, posing challenges in clinical management and surgical intervention.

METHODS

This study analyzed talar morphology in individuals with CMT compared with a healthy control group, employing a single-bone statistical shape model and talar neck offset angle measurements. Participants included 18 CMT individuals (yielding 29 tali) and 43 healthy controls. For individuals with CMT, the average age at diagnosis was 36.5 ± 19.8 years, with a mean interval of 8.6 years between diagnosis and imaging. Talar morphology was evaluated using weightbearing computed tomography and subsequent morphologic and angular analysis.

RESULTS

Differences were observed in talar morphology between CMT and healthy individuals. Notably, CMT1 and CMT2 tali exhibited a flatter talar dome and more medial talar head and neck compared with controls. Additionally, the CMT1 and CMT2 subgroups both had a more medially oriented talar neck based on the talar neck offset angle compared with the controls.

CONCLUSION

The findings illustrate significant morphologic variations in the talus of CMT patients, indicating the need for type-specific clinical approaches in treating CMT-related foot deformities. Understanding these talar variations is crucial for tailoring surgical techniques and orthotic designs, and developing effective rehabilitation protocols for individuals with CMT, potentially improving patient care and outcomes.

Standardizing 3 Dimensional Measurements in Foot and Ankle Imaging: A Contemporary Review and Methodological Proposal

Increasing utilization of weight-bearing computed tomography and fluoroscopy has driven the need for standardization of 3 dimensional (3D) measurements in the foot and ankle. These emerging imaging modalities are currently used to evaluate foot and ankle conditions including ankle osteoarthritis, progressive collapsing foot deformity, midfoot instability, and hallux valgus. This study aims first to provide a comprehensive review of clinical studies that have utilized these 3D methodologies. As a second goal, this study presents the methodological approach proposed by an international task force of experts toward addressing those concerns to provide validated guidelines for 3D static and dynamic measurements.

Méary's angle decoded: 3D analysis of first ray plantarflexion deformity in Charcot-marie-tooth disease

BACKGROUND

The typical cavovarus deformity seen in patients with Charcot-Marie-Tooth (CMT) involves plantarflexion of the first ray. 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 first ray plantarflexion deformity in CMT patients.

METHODS

WBCTs of 16 CMT patients with lateral Méary's angle > 20 degrees were compared to controls utilizing semi-automated analysis software. A local coordinate system based on the first metatarsal was used to avoid bias of proximal deformity. The tarsometatarsal angle was subdivided into components (cuneiform-cuneiform joint normal, tarsometatarsal joint and metatarsal-metatarsal joint normal) and compared between CMT and controls. CMT patient's first, second and third rays were also compared. Means were compared with a 2-sample t test (p < .05).

RESULTS

CMT patients had significantly more plantarflexion of the first ray than controls (16.4 versus 8.8 degrees respectively(p < 0.001)). The largest difference of was found at the medial cuneiform with 20.6 degrees of plantarflexion in CMT patients versus 14.8 degrees in controls (p < .0001). There was also approximately 2 degrees of plantarflexion at the TMT joint (p < .001).

CONCLUSIONS

Plantarflexion deformity in CMT patients is primarily an osseous deformity at the level of the medial cuneiform with a lesser contribution from the tarsometatarsal joint.

LEVEL OF EVIDENCE

III Retrospective comparative study.

Outcomes of Charcot-Marie-Tooth Disease Cavovarus Surgical Reconstruction

BACKGROUND

Charcot-Marie-Tooth (CMT) disease is a progressive inherited neurologic disorder causing muscle weakness and lower extremity deformity. The goal of foot and ankle surgical treatment is to create a stable, plantigrade foot, with the potential elimination of brace-wear for ambulation. The aim of this study was to report baseline CMT patient function and subsequent outcome improvement from surgical treatment, as determined by PROMIS physical function (PF), pain interference (PI), and mental health/depression (D) scores.

METHODS

Retrospective data were collected on consecutive CMT patients older than 18 years receiving surgical treatment by the senior surgeon at Cedars-Sinai Medical Center from 2018 to 2022 with minimum 1-year follow-up. Each patient prospectively completed PROMIS preoperatively and postoperatively after all planned surgical treatment was completed. Prospective clinical and radiographic data were collected to describe complications and correlation to outcome.

RESULTS

Ninety-five feet in 64 patients older than 18 years were included for analysis. Mean follow-up was 21 months (range, 12-31) with 100% minimum 1-year follow-up. CMT patients had worse preoperative and baseline scores in all domains except PROMIS-D compared with population normal PROMIS scores. Significant improvements were identified in all PROMIS domains following surgical treatment. The mean PROMIS-PF score increased (40 to 45, delta = 4.9, P < .001), the mean PROMIS-PI score decreased (59 to 52, delta = 7.1, P < .001), and the mean PROMIS-D score decreased (50 to 47, delta = 3.0, P = .004). Subgroup analysis was performed for patients with severe radiographic deformity and those treated with arthrodesis in an attempt to demonstrate the impact of disease severity on outcome. Subgroup analysis demonstrated that arthrodesis led to worse overall PROMIS-PF outcome with the same change score.

CONCLUSION

Surgical treatment for CMT patients provides significant clinical improvement in all measured outcome domains. CMT patients can be restored to normal population physical function and pain interference outcome scores. Patients with more severe deformity have similar improvement from surgical treatment, although their ultimate functional improvement is blunted due to a lower baseline.

Trends in the Use of Weightbearing Computed Tomography

Background: This review aimed to critically appraise the most recent orthopedic literature around cone beam weightbearing computed tomography (WBCT), summarizing what evidence has been provided so far and identifying the main research trends in the area. Methods: This scoping review was performed on studies published between January 2013 and December 2023 on the Pubmed database. All studies (both clinical and nonclinical) in which WBCT had been used were critically analyzed to extract the aim (or aims) of the study, and the main findings related to the role of this imaging modality in the diagnostic pathway. Results: Out of 1759 studies, 129 were selected. One hundred five manuscripts (81%) dealt with elective orthopedic conditions. The majority of the analyses (88 studies; 84%) were performed on foot and ankle conditions, while 13 (12%) studies looked at knee pathologies. There was a progressive increase in the number of studies published over the years. Progressive Collapsing Foot Deformity (22 studies; 25%) and Hallux Valgus (19 studies; 21%) were frequent subjects. Twenty-four (19%) manuscripts dealt with traumatic conditions. A particular interest in syndesmotic injuries was documented (12 studies; 60%). Conclusions: In this review, we documented an increasing interest in clinical applications of weightbearing CT in the orthopedic field between 2013 and 2023. The majority of the analyses focused on conditions related to the foot and the ankle; however, we found several works investigating the value of WBCT on other joints (in particular, the knee).

Forefoot Morphotypes in Cavovarus Feet: A Novel Assessment of Deformity

BACKGROUND

The cavovarus foot is a complex 3-dimensional deformity. Although a multitude of techniques are described for its surgical management, few of these are evidence based or guided by classification systems. Surgical management involves realignment of the hindfoot and soft tissue balancing, followed by forefoot balancing. Our aim was to analyze the pattern of residual forefoot deformities once the hindfoot is corrected, to guide forefoot correction.

METHODS

We included 20 cavovarus feet from 16 adult patients with Charcot-Marie-Tooth who underwent weightbearing CT (mean age 43.4 years, range: 22-78 years, 14 males). Patients included had flexible deformities, with no previous surgery. Using specialized software (Bonelogic 2.1, Disior) a 3-dimensional, virtual model was created. Using morphologic data captured from normal feet in patients without pathology as a guide, the talonavicular joint of the cavovarus foot was digitally reduced to a "normal" position to simulate the correction that would be achieved during surgical correction. Models of the corrected position were exported and geometrically analyzed using Blender 3.64 to identify anatomical trends.

RESULTS

We identified 4 types of cavovarus forefoot morphotypes. Type 0 was defined as a balanced forefoot (2 cases, 10%). Type 1 was defined as a forefoot where the first metatarsal was relatively plantarflexed to the rest of the foot, with no significant residual adduction after talonavicular joint correction (12 cases, 60%). Type 2 was defined as a forefoot where the second and first metatarsals were progressively plantarflexed, with no significant adduction (4 cases, 20%). Type 3 was defined as a forefoot where the metatarsals were adducted after talonavicular derotation (2 cases, 10%).

CONCLUSION

In this relatively small cohort, we identified 4 forefoot morphotypes in cavovarus feet that might help surgeons to recognize and anticipate the residual forefoot deformities after hindfoot correction. Different treatment strategies may be required for different morphotypes to achieve balanced correction.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

3D Analysis of Joint-Sparing Charcot-Marie-Tooth Surgery Effect on Initial Standing Foot Alignment

BACKGROUND

The complex deformities in cavovarus feet of Charcot-Marie-Tooth (CMT) disease are difficult to evaluate. The aim of this study was to quantify the initial standing alignment correction achieved after joint-sparing CMT cavovarus reconstruction using pre- and postoperative weightbearing computed tomography (WBCT).

METHODS

Twenty-nine CMT cavovarus reconstructions were retrospectively analyzed. Three-dimensional measurements were performed using semiautomated software (Bonelogic 2.1) to investigate changes in sagittal, axial, and coronal parameters. Pre- and postoperative data were compared, along with normative data. Correlation among the preoperative measurements and the amount of correction in sagittal, axial, and coronal parameters were analyzed.

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 angle (from 14.8 to 0.1 degrees), axial talonavicular angle (TNA, from 3.6 to 19.2 degrees), and coronal hindfoot alignment (from 11.0 to -11.1 degrees) showed significant changes postoperatively (P < .001). Hindfoot, forefoot sagittal, and forefoot axial parameters reached comparable outcomes compared with normative value (P > .05). Regarding amount of correction, Spearman correlation demonstrated that axial Meary angle and TNA were most strongly related to improvement in sagittal Meary 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 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 cavovarus foot correction.

Classifications in adult pes cavus - A scoping review

AIMS

The adult cavus foot represents a challenging clinical problem, with varied aetiology and complex, 3-dimensional deformities. Thus far, the cavus foot has eluded a unified classification. The aim of this paper was to appraise the literature to identify classification systems which guide the operative management of neurological cavus feet in adults.

METHODS

As the aim of this paper was broad, a scoping review was conducted. The review was conducted in line with published frameworks. Our principal research question was 'what classification systems that guide surgical management currently exist for neurological cavus feet in adults'. We searched CINAHL, Embase, OVID, Proquest, Pubmed, Scopus and Web of Science databases using MESH and non-MESH terms. Two authors independently reviewed abstracts / papers and a data extraction sheet was used to collect the relevant data.

RESULTS

A total of 1140 articles were initially screened, identifying 125 articles for which a full text review was performed. Only three articles met all our inclusion criteria. All these articles reported an anatomical classification with suggestions for treatment based on the classification. All were considered to comprise Level V evidence, and none reported outcomes of treatment based on the classification.

CONCLUSIONS

There is currently a paucity of robust classifications to guide treatment in neurological cavus feet in adults. The few classifications systems that exist are varied and do not as yet have sufficient evidence to support their widespread use. Further work is required, aimed at identifying specific features of cavus feet that would guide operative treatment.

Charcot-Marie-Tooth Disease: A Surgical Algorithm

In Charcot-Marie-Tooth (CMT) cavovarus surgery, a regimented approach is critical to create a plantigrade foot, restore hindfoot stability, and generate active ankle dorsiflexion. The preoperative motor examination is fundamental to the algorithm, as it is not only guides the initial surgical planning but is key in the decision making that occurs throughout the operation. Surgeons need to be comfortable with multiple techniques to achieve each surgical goal. There is no one operation that works for all patients with CMT. A plantigrade foot is the most important of the surgical goals as hindfoot stability and ankle dorsiflexion can be augmented with bracing.

Ankle Instability and Peroneal Disorders in Cavovarus Feet: Do I Need a Calcaneal Osteotomy?

In order to understand the relation among ankle instability, peroneal disorders, and cavovarus deformity, it is mandatory to clarify the different stages of those disorders and also to put them into relation to each other. Finally, we need to take the patients compliance and expectations into consideration to define the individually right way of treatment.