456 C OPYRIGHT Ó 2014
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Tibialis Posterior Tendon Transfer Corrects the Foot Drop Component of Cavovarus Foot Deformity in Charcot-Marie-Tooth Disease T. Dreher, MD, S.I. Wolf, PhD, D. Heitzmann, MSc, C. Fremd, M.C. Klotz, MD, and W. Wenz, MD Investigation performed at the Division for Paediatric Orthopaedics and Foot Surgery, Department for Orthopaedic and Trauma Surgery, Heidelberg University Clinics, Heidelberg, Germany
Background: The foot drop component of cavovarus foot deformity in patients with Charcot-Marie-Tooth disease is commonly treated by tendon transfer to provide substitute foot dorsiflexion or by tenodesis to prevent the foot from dropping. Our goals were to use three-dimensional foot analysis to evaluate the outcome of tibialis posterior tendon transfer to the dorsum of the foot and to investigate whether the transfer works as an active substitution or as a tenodesis. Methods: We prospectively studied fourteen patients with Charcot-Marie-Tooth disease and cavovarus foot deformity in whom twenty-three feet were treated with tibialis posterior tendon transfer to correct the foot drop component as part of a foot deformity correction procedure. Five patients underwent unilateral treatment and nine underwent bilateral treatment; only one foot was analyzed in each of the latter patients. Standardized clinical examinations and three-dimensional gait analysis with a special foot model (Heidelberg Foot Measurement Method) were performed before and at a mean of 28.8 months after surgery. Results: The three-dimensional gait analysis revealed significant increases in tibiotalar and foot-tibia dorsiflexion during the swing phase after surgery. These increases were accompanied by a significant reduction in maximum plantar flexion at the stance-swing transition but without a reduction in active range of motion. Passive ankle dorsiflexion measured in knee flexion and extension increased significantly without any relevant decrease in passive plantar flexion. The AOFAS (American Orthopaedic Foot & Ankle Society) score improved significantly. Conclusions: Tibialis posterior tendon transfer was effective at correcting the foot drop component of cavovarus foot deformity in patients with Charcot-Marie-Tooth disease, with the transfer apparently working as an active substitution. Although passive plantar flexion was not limited after surgery, active plantar flexion at push-off was significantly reduced and it is unknown whether this reduction was the result of a tenodesis effect or calf muscle weakness. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2014;96:456-62
d
http://dx.doi.org/10.2106/JBJS.L.01749
A commentary by Michael S. Aronow, MD, is linked to the online version of this article at jbjs.org.
457 TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 6 M A R C H 19, 2 014 d
d
d
A
cavovarus foot deformity may limit quality of life, reducing the ability to perform daily activities, and it may be associated with a high level of disability1,2. CharcotMarie-Tooth disease3 represents one of the most common neurogenic causes of bilateral cavovarus foot4. This progressive disease is caused by malfunction of the myelin sheath leading to muscle atrophy and muscle imbalance5-9. An abnormal gait, painful callus formation, and ankle instability may develop as part of the characteristic cavovarus foot deformity5-9. One important etiologic factor is weakness of the tibialis anterior muscle, which presents clinically as foot drop. In combination with an abnormally strong pull by the peroneus longus to compensate for peroneus brevis weakness, tibialis anterior weakness is a major underlying cause of cavovarus foot10,11. As a result of foot drop, gait impairment can occur during the swing and stance phases of the gait cycle. Ferrarin et al. defined three gait patterns in young patients with Charcot-Marie-Tooth disease according to the results of a clustering analysis: pseudonormal, foot drop only, and foot drop with a push-off deficit11. Various procedures have been described to correct the foot drop component during a surgical intervention to correct the
TIBIALIS POSTERIOR TENDON TRANSFER CORRECTS THE FOOT D R O P C O M P O N E N T O F C AVO VA R U S F O O T D E F O R M I T Y
foot deformity12,13. Some authors recommend transfer of the tibialis posterior tendon to the dorsum of the foot and report satisfactory results12-16. However, previous studies have lacked an objective evaluation of ankle function after this transfer. Tendons are transferred to create an active substitution for a weak muscle or a tenodesis effect to dynamically fix a joint in a favorable position. An active substitution should be preferred for patients who are potentially able to relearn active function, such as patients with Charcot-Marie-Tooth disease. The tibialis posterior normally generates an internal plantar flexing moment and is coactivated with other plantar flexors (calf muscles and long toe flexors)17; however, it is not known whether it can adapt to a different activation pattern and act as an active dorsiflexor after being transferred to the dorsum of the foot in patients with Charcot-Marie-Tooth disease. These effects have not yet been investigated and compared with each other. A major limitation of the use of conventional gait analysis models18 in evaluating foot deformities is their representation of the foot as a single rigid lever. The cavovarus foot also involves forefoot equinus (cavus), and changes in the arch as a result of cavus correction have a major impact on sagittal ankle
TABLE I Outcomes for the Fourteen Involved Feet Parameter
Baseline*
Follow-up*
Clinical examination AOFAS hindfoot score Passive ankle dorsiflexion at 90° knee flexion (deg) Passive ankle dorsiflexion in knee extension (deg) Passive ankle plantar flexion (deg) Range of passive ankle dorsiflexion and plantar flexion in knee extension (deg)
55 ± 11 0 ± 11 24 ± 11 45 ± 5 41 ± 12
HFMM three-dimensional gait and foot analysis (deg) Swing phase Max. tibiotalar dorsiflexion Max. tibiotalar plantar flexion Range of tibiotalar dorsiflexion and plantar flexion Max. foot-tibia dorsiflexion Max. foot-tibia plantar flexion Range of foot-tibia dorsiflexion and plantar flexion Stance phase Max. tibiotalar dorsiflexion Max. tibiotalar plantar flexion Range of tibiotalar dorsiflexion and plantar flexion Max. foot-tibia dorsiflexion Max. foot-tibia plantar flexion Range of foot-tibia dorsiflexion and plantar flexion Mean medial arch Lateral standing radiograph (deg) Calcaneal pitch Talometatarsal angle
P Value†
Normal*
76 ± 10‡ 15 ± 6‡ 9 ± 5‡ 36 ± 8‡ 45 ± 9‡
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Tibialis Posterior Tendon Transfer Corrects the Foot Drop Component of Cavovarus Foot Deformity in Charcot-Marie-Tooth Disease T. Dreher, MD, S.I. Wolf, PhD, D. Heitzmann, MSc, C. Fremd, M.C. Klotz, MD, and W. Wenz, MD Investigation performed at the Division for Paediatric Orthopaedics and Foot Surgery, Department for Orthopaedic and Trauma Surgery, Heidelberg University Clinics, Heidelberg, Germany
Background: The foot drop component of cavovarus foot deformity in patients with Charcot-Marie-Tooth disease is commonly treated by tendon transfer to provide substitute foot dorsiflexion or by tenodesis to prevent the foot from dropping. Our goals were to use three-dimensional foot analysis to evaluate the outcome of tibialis posterior tendon transfer to the dorsum of the foot and to investigate whether the transfer works as an active substitution or as a tenodesis. Methods: We prospectively studied fourteen patients with Charcot-Marie-Tooth disease and cavovarus foot deformity in whom twenty-three feet were treated with tibialis posterior tendon transfer to correct the foot drop component as part of a foot deformity correction procedure. Five patients underwent unilateral treatment and nine underwent bilateral treatment; only one foot was analyzed in each of the latter patients. Standardized clinical examinations and three-dimensional gait analysis with a special foot model (Heidelberg Foot Measurement Method) were performed before and at a mean of 28.8 months after surgery. Results: The three-dimensional gait analysis revealed significant increases in tibiotalar and foot-tibia dorsiflexion during the swing phase after surgery. These increases were accompanied by a significant reduction in maximum plantar flexion at the stance-swing transition but without a reduction in active range of motion. Passive ankle dorsiflexion measured in knee flexion and extension increased significantly without any relevant decrease in passive plantar flexion. The AOFAS (American Orthopaedic Foot & Ankle Society) score improved significantly. Conclusions: Tibialis posterior tendon transfer was effective at correcting the foot drop component of cavovarus foot deformity in patients with Charcot-Marie-Tooth disease, with the transfer apparently working as an active substitution. Although passive plantar flexion was not limited after surgery, active plantar flexion at push-off was significantly reduced and it is unknown whether this reduction was the result of a tenodesis effect or calf muscle weakness. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2014;96:456-62
d
http://dx.doi.org/10.2106/JBJS.L.01749
A commentary by Michael S. Aronow, MD, is linked to the online version of this article at jbjs.org.
457 TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O L U M E 96-A N U M B E R 6 M A R C H 19, 2 014 d
d
d
A
cavovarus foot deformity may limit quality of life, reducing the ability to perform daily activities, and it may be associated with a high level of disability1,2. CharcotMarie-Tooth disease3 represents one of the most common neurogenic causes of bilateral cavovarus foot4. This progressive disease is caused by malfunction of the myelin sheath leading to muscle atrophy and muscle imbalance5-9. An abnormal gait, painful callus formation, and ankle instability may develop as part of the characteristic cavovarus foot deformity5-9. One important etiologic factor is weakness of the tibialis anterior muscle, which presents clinically as foot drop. In combination with an abnormally strong pull by the peroneus longus to compensate for peroneus brevis weakness, tibialis anterior weakness is a major underlying cause of cavovarus foot10,11. As a result of foot drop, gait impairment can occur during the swing and stance phases of the gait cycle. Ferrarin et al. defined three gait patterns in young patients with Charcot-Marie-Tooth disease according to the results of a clustering analysis: pseudonormal, foot drop only, and foot drop with a push-off deficit11. Various procedures have been described to correct the foot drop component during a surgical intervention to correct the
TIBIALIS POSTERIOR TENDON TRANSFER CORRECTS THE FOOT D R O P C O M P O N E N T O F C AVO VA R U S F O O T D E F O R M I T Y
foot deformity12,13. Some authors recommend transfer of the tibialis posterior tendon to the dorsum of the foot and report satisfactory results12-16. However, previous studies have lacked an objective evaluation of ankle function after this transfer. Tendons are transferred to create an active substitution for a weak muscle or a tenodesis effect to dynamically fix a joint in a favorable position. An active substitution should be preferred for patients who are potentially able to relearn active function, such as patients with Charcot-Marie-Tooth disease. The tibialis posterior normally generates an internal plantar flexing moment and is coactivated with other plantar flexors (calf muscles and long toe flexors)17; however, it is not known whether it can adapt to a different activation pattern and act as an active dorsiflexor after being transferred to the dorsum of the foot in patients with Charcot-Marie-Tooth disease. These effects have not yet been investigated and compared with each other. A major limitation of the use of conventional gait analysis models18 in evaluating foot deformities is their representation of the foot as a single rigid lever. The cavovarus foot also involves forefoot equinus (cavus), and changes in the arch as a result of cavus correction have a major impact on sagittal ankle
TABLE I Outcomes for the Fourteen Involved Feet Parameter
Baseline*
Follow-up*
Clinical examination AOFAS hindfoot score Passive ankle dorsiflexion at 90° knee flexion (deg) Passive ankle dorsiflexion in knee extension (deg) Passive ankle plantar flexion (deg) Range of passive ankle dorsiflexion and plantar flexion in knee extension (deg)
55 ± 11 0 ± 11 24 ± 11 45 ± 5 41 ± 12
HFMM three-dimensional gait and foot analysis (deg) Swing phase Max. tibiotalar dorsiflexion Max. tibiotalar plantar flexion Range of tibiotalar dorsiflexion and plantar flexion Max. foot-tibia dorsiflexion Max. foot-tibia plantar flexion Range of foot-tibia dorsiflexion and plantar flexion Stance phase Max. tibiotalar dorsiflexion Max. tibiotalar plantar flexion Range of tibiotalar dorsiflexion and plantar flexion Max. foot-tibia dorsiflexion Max. foot-tibia plantar flexion Range of foot-tibia dorsiflexion and plantar flexion Mean medial arch Lateral standing radiograph (deg) Calcaneal pitch Talometatarsal angle
P Value†
Normal*
76 ± 10‡ 15 ± 6‡ 9 ± 5‡ 36 ± 8‡ 45 ± 9‡
