Cavovarus deformity in Charcot-Marie-Tooth disease: is there a hindfoot equinus deformity that needs treatment?

Characteristic 3D foot motion patterns during gait of patients with Charcot-Marie-Tooth identified by cluster analysis

BACKGROUND

CMT is a clinically and genetically heterogenous disease with varying degrees of progression. Different foot deformities, gait and movement patterns are observed. In order to achieve an improved, targeted treatment strategy, the participants are divided into characteristic groups using a mathematical cluster analysis based on the data from the three-dimensional foot kinematics during walking.

METHODS

Outpatients from age 5-64 years (N = 33 participants, 62 feet) with a proven CMT type 1 (N = 16, 31 feet) or CMT without any further type assignment (N = 17, 31 feet) were retrospectively analyzed. After a standard clinical examination, participants underwent 3D gait analysis using the Oxford Foot Model. To classify the movement patterns, a k-means cluster analysis was calculated based on the principal component analysis (PCA) of the foot kinematics data. Gait parameters, clinical parameters and X-ray data were statistically tested.

RESULTS

The cluster analysis divided the gait data of the participants into two groups. Cluster 1 (N = 21 participants, 34 feet) showed increased dorsiflexion of the hindfoot and increased plantarflexion of the forefoot with cavus position in the sagittal plane, a hindfoot inversion and forefoot pronation with hindfoot varus in the frontal plane and in the transversal plane a forefoot adduction. Cluster 2 (N = 17 participants, 28 feet) deviated significantly from the norm mainly in the frontal plane and were characterized by a strong eversion of the hindfoot with a supination in the forefoot.

DISCUSSION

Based on the findings, the resultant clusters can be interpreted as cavovarus feet (cluster 1) and pes valgus (cluster 2). The most reliable variables in the 3D gait analysis to classify CMT feet with regard to significance are the ones in the frontal plane. This subdivision of participants goes hand in hand with the various necessary guidelines for orthopedic treatment.

Gait analysis of leprosy patients with foot drop using principal component analysis

BACKGROUND

Peripheral nerve injury caused by leprosy can lead to foot drop, resulting in an altered gait pattern that has not been previously described using 3D gait analysis.

METHODS

Gait kinematics and dynamics were analyzed in 12 patients with unilateral foot drop caused by leprosy and in 15 healthy controls. Biomechanical data from patients' affected and unaffected limbs were compared with controls using inferential statistics and a standard distance, based on principal components analysis (PCA).

FINDINGS

Patients walked slower than controls (0.8 ± 0.2 vs. 1.1 ± 0.2 m/s, p = 0.003), with a reduced stance and increased swing percentage. The affected limb increased (p < 0.05) plantar flexion at the initial contact (-16.8^o ± 8.3), terminal stance (-29.1^o ± 11.5), and swing (-12.4^o ± 6.2) in the affected limb compared to unaffected (-6.6^o ± 10.3; -14.6^o ± 11.6; 2.4^o ± 7.6) and controls (-5.4^o ± 2.5; -18.8^o ± 5.8; -1.4^o ± 3.9). Increased pelvic tilt and knee adduction/abduction range, with lower hip adduction, were observed. The second peak of ground reaction force (98.6 ± 5.2 %BW), ankle torque (0.99 ± 0.33 Nm/kg), and net ankle work in stance (-0.03 ± 5.4 J/Kg) decreased in the affected limb compared to controls (104.1 ± 5.5 %BW; 1.24 ± 0.4 Nm/kg; -4.58 ± 5.19 J/kg; p < 0.05). There were decreasing multivariate standard distances in the affected limb compared with the unaffected and controls. PCA loading factors highlighted the major differences between groups.

INTERPRETATION

Leprosy patients with foot drop presented altered gait patterns in affected and unaffected limbs. There were remarkable differences in ankle kinematics and dynamics. Rehabilitation devices, such as ankle foot orthosis or tendon transfer surgeries to increase ankle dorsiflexion, could benefit these patients and reduce deviations from normal gait.

Neurologic Disorders and Cavovarus Deformity

A cavovarus deformity results from muscle imbalances in the foot. There are several etiologies of a cavovarus foot including congenital, neurologic, post-traumatic, and idiopathic. Charcot-Marie-Tooth disease is a common genetic cause of cavovarus foot. History, physical examination, and imaging help determine appropriate treatment. The deformity can be flexible or rigid and can present in children or adults, thus treatment should be individualized to the patient. Non-operative management includes shoe wear modification, physical therapy, and bracing. Operative management consists of soft tissue releases, tendon transfers, osteotomies, arthrodesis, and repair/reconstruction of lateral ankle ligaments and peroneal tendons.

[Components of the joint-sparing, combined bony and soft tissue correction of the cavovarus foot]

OBJECTIVE

Combined bony and soft tissue correction of a mild foot and flexible rearfoot deformity in cavovarus foot.

INDICATIONS

Drop foot during swing phase and muscular imbalance in the stance phase in cavovarus foot, flexible cavovarus foot, accompanying symptoms such as recurrent calluses and ulcerations, compliance.

CONTRAINDICATIONS

Pes cavovarus of spastic genesis, mild deformities, fixed bony deformity, lack of compliance, florid inflammation in the foot area, severe peripheral artery disease (PAD), diabetes mellitus.

SURGICAL TECHNIQUE

Description of the gradual escalation of joint-sparing bony and soft tissue procedures.

POSTOPERATIVE MANAGEMENT

Postoperative lower leg cast. In cases of combined bony and soft tissue correction, first 6 weeks of nonweight-bearing with lower leg cast, then 6 weeks of lower leg walking cast. With adequate bony consolidation, cast removal after a total of 12 weeks. In cases of pure soft-tissue foot correction, 6 weeks of lowerleg walking cast.

RESULTS

It was shown that only 22.5% of the affected feet (40 preoperative patients with cavovarus foot deformity) had a severe hindfoot equinus due to shortened calf muscles. In a study with 14 patients, it was shown that the tibialis posterior tendon transfer corrects the drop foot component and the excessive medial arch of the feet is significantly reduced by combined soft tissue and bony procedures.