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The need for biomechanical evaluation in the assessment of clubfoot
The Foot 14 (2004) 72–76
Review
The need for biomechanical evaluation in the assessment of clubfoot F. Herd a , M. Macnicol b , R.J. Abboud a,∗ a
Institute of Motion Analysis and Research (IMAR), Department of Orthopaedics and Trauma Surgery, T.O.R.T. Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK b Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 1LF, UK Received 1 September 2003; accepted 9 December 2003
Abstract Clubfoot is a complex deformity found in one in a thousand children. It frequently causes disability—either from the original deformity or because of secondary conditions and problems associated with treatment. The management remains varied and controversial. Currently, mixtures of different methods are used to assess the severity of the deformity. However, none is ideal. Biomechanical assessment involves the evaluation of forces and motion of the musculoskeletal system and includes the analysis of foot pressure distribution and gait parameters. The aim of this article is to discuss the various assessment techniques available and demonstrate the need for, and advantages of, biomechanical assessment. © 2004 Elsevier Ltd. All rights reserved. Keywords: Clubfoot; Assessment; Foot pressure; Gait analysis; Biomechanics
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Assessment of clubfoot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Clinical assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Radiological assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Functional. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4. Biomechanical assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1. Foot pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2. Giat analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. 2.
1. Introduction Clubfoot encompasses a spectrum of foot deformity that frequently results in long-term deformity and disability and presents considerable challenges to the orthopaedic surgeon. The controversy exists because the exact pathogenesis and pathological anatomy remain unknown, there is no agreed method of assessment and no uniform management. Assessment is essential for the prescription and evaluation of treatment, as well as predicting prognosis [1]. Cur∗ Corresponding author. Tel.: +44-1382-496332; fax: +44-1382-496200. E-mail address: [email protected] (R.J. Abboud).
0958-2592/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.foot.2003.12.004
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rently, combinations of clinical, functional and radiological techniques are used. These are subjective and hard to repeat and often do not show important or subtle changes. Consequently it is hard to evaluate the outcome of each type of treatment objectively.
2. Assessment of clubfoot Assessment provides a method of classifying the severity of the original deformity and evaluating the success of treatment. Previous research has indicated that the outcome of treatment is related to the initial severity of the deformity [2,3] and therefore, classification is used as a guide to prog-
F. Herd et al. / The Foot 14 (2004) 72–76
nosis. Quantitative data allows comparison facilitating monitoring of success of treatment and progression of deformity or relapse. Detection of subtle signs of deformity would allow earlier, simpler management and prevent the progression of severe and permanent damage. This includes secondary conditions such as osteoarthritis, which could cause further disability. An enhanced system of classification would ensure that all children receive the appropriate management, i.e. further surgery and/or orthotic support. This would provide them with the best possible function of the limb and, hence, quality of life now and in the future. The ability to objectively evaluate each type of treatment would also allow comparison of techniques, which might result in the formulation of a universal management strategy. There is no universal method for the assessment of clubfoot. A variety of techniques are used including clinical, functional and radiological investigations. Currently, a mixture of subjective and objective methods is used to assess the clubfoot [4,5]. 2.1. Clinical assessment Clinical parameters make up the most common form of assessment and involve measuring the extent of the fixed deformity, its rigidity and reducibility. Other aspects include the range of movement, bimalleolar angle, presence of creases (medial and posterior), calf wasting and foot size, strength and whether pressure on first ray causes subluxation (telescoping). Clinical measurements focus on cosmetic appearance and are often static. Most of this data is subjective, affected by interobserver error and hard to repeat [6]. Visual interpretation of outcome is poor. Both Hee et al. [6] and Hutichson et al. [7] surmised that what appeared to be a cosmetically good foot did not necessarily have a good function. Numerous classification/assessment systems have been published, each incorporating a different set of parameters with varied weighting. This makes comparison of results difficult. Cental et al. [8] stated that in young children the ratio of soft tissue to bone is at its maximum, thus any management decision based on clinical appearance alone would be misleading hence identifying the need for another method of examination. Photography and cinematography show visual changes but cannot provide objective quantitative data [4]. 2.2. Radiological assessment Radiographs define the precise anatomical relationship of joints. Simons [9] suggested studying the talocalcaneal index—derived by adding the lateral and antero-posterior angles together. He stated that a normal individual had an index above 50◦ but this was much lower in the clubfoot patient group. Successful correction can result in an index over 50. However, most post-operative patients show a lower index
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[10], Laveg and Ponseti [11] found that the lateral talocalcaneal angle correlated well with functional rating and patient satisfaction. However, Wynne Davis [12] questioned the use of radiological outcomes as early as 1964. Inter alia, several studies [3,13–15] did not correlate well with clinical parameters and could not be used to predict outcome. Hutchins et al. [16] maintained that anatomical normality is never achieved, thus an assessment technique looking at anatomical realignment is poor. Problems with radiological measurements include repeatability and difficulty in positioning the foot correctly [17]. In addition, conventional radiography cannot give reliable information at a young age due to lack of ossification of bones. Furthermore, the ossified nucleus has been shown to appear later in children with CTEV [18]. Therefore, it is not an ideal method of assessment. 2.3. Functional Functional assessment examines the ability to carry out daily tasks and incorporates the patient’s subjective opinion regarding outcome and disability. Activity levels, walking, sporting capability, presence of a limp, pain, shoes, appearance and satisfaction are all considered. Pre-operative assessment is difficult if the child is still young with limited mobility. Repeatability is poor [6] and is subjective, with answers depending on mood of patient and the manner in which the questions are asked. Often the patient can misinterpret the point or the interviewer misconstrue the answer. With young children parents may have to answer by proxy and the age of child could affect the answers given. However, this is probably the area most important to the patient. Roye et al. [15] developed a disease specific index (DSI) that looked at the function of the limb and the satisfaction of the parent/child. They found a relationship between some clinical parameters and functional outcome. For example, patients with increased heel varus were more likely to complain of decreased satisfaction and poor running ability. None of the above methods are objective or completely reliable thus the search continues to identify a new technique. Therefore, there is a need for an objective method of assessment to produce data which can assess initial severity, predict prognosis, determine necessary treatment, evaluate outcome and detect relapse or poor correction [1]. Wallander et al. [19] concluded that currently there is no ideal rating system, but one which pays more attention to function, such as gait and foot pressure, rather than appearance alone would be useful. The ideal form of assessment would produce objective, quantitative and functional data as well as being simple, reproducible, reliable, cheap and safe. A corrected foot is plantigrade, functional and pain free (inter alia [14,20]), but assessing this is difficult. It is essential for the clinician to understand the changes in the foot under dynamic activity [6]. There is also some discord over which features are the most important, for example, does excellent function override anatomical imperfections? Perhaps a mild equinus
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deformity with stronger plantarflexors is more functional than a weaker plantigrade foot [21]. 2.4. Biomechanical assessment Foot deformities interfere with the ability to walk and induce symptoms because of abnormal distribution of load under the plantar surface of the foot. Therefore, there is a need to assess the foot biomechanically [1], including the study of kinetics (force and motion) and kinematics (motion irrespective of force). This enables evaluation of foot function at time of contact with floor, plus analysis of forces and their effects on anatomical structures. Hee et al. [7] stated that, although corrected clubfeet look good and function well; more objective analysis revealed that the biomechanical functions of the foot were not entirely normal. Research has been undertaken involving the use of foot pressure and gait analysis to provide objective, functional and biomechanical data for evaluation of clubfeet. Previous work has focused on the identification of abnormalities present in children with clubfeet. However, no agreement has been reached on the specific role that these techniques have to offer. For example, there is the question of whether they can be used as a method of assessing initial severity and prognosis or to determine and evaluate treatment. 2.4.1. Foot pressure In healthy normal individuals, plantar pressure is distributed under the load-bearing areas such as the heel, metatarsal heads and phalanges [22]. Abnormalities in either structure or function of the foot can alter this pattern and lead to areas of dangerously abnormal pressure where callosities or other injury can occur. Simple observation of the foot alone could mislead the clinician, but analysis of plantar pressure can assist anatomical inspection. Over the last 20 years many techniques for the measurement of pressure distribution underneath the plantar surface of the foot have arisen, although none fulfils the ideal characteristics [1]. The data produced yields objective qualitative and quantitative information about foot structure and function. Foot pressure can be static (standing), or dynamic (measuring pressures exerted during the gait cycle, for example, whilst walking). Currently, it is used in many specialities of medicine, for both assessment and post-operative review, and in sport. Bowen et al. [23] claimed that foot pressure data is a diagnostic method to measure the severity of any foot deformity and can quantify the changes resulting from surgery, hence fulfilling some of the criteria identified above. These techniques have already found a place in the assessment of rheumatoid arthritis, cerebral palsy and diabetes mellitus [24]. However, foot pressure is also affected by age, size, weight and gait velocity [25,26]. Therefore, when assessing children over a number of years the effects of growth must be taken into account. The lack of literature defining foot pressure in normal children makes evaluation more difficult.
Recent literature review shows the research areas involving the use of foot pressure analysis. The deformity can be analyzed simply by looking at the shape and pattern of the print. Kumar [27] used serial inked footprints to demonstrate the progression of the deformity and show the need for surgical management. No one has evaluated the use of foot pressure in assessing the original untreated deformity. Assessments of children with a secondary equinovarus reported a lack of heel pressure and increased forefoot loading, particularly laterally [28]. Hutchinson et al. [6] found that dynamic peak pressure shifted medially and posteriorly after surgery showing correction of equinovarus. However, Hee et al. [7] demonstrated that the hindfoot of the treated clubfoot population bears less pressure than forefoot when standing and Aronson and Puskarich [21] found increased pressure under the fifth metatarsal head in their treated group, both of which suggest some residual deformity. Brand et al. [29] correlated a functional rating with the centre of pressure but concluded that the centre of pressure was not sensitive enough to distinguish between normal and affected feet. Cooper and Dietz [14] and Huang et al. [20] found that foot pressure data can distinguish between those with an excellent/good clinical outcome and those with poor/fair outcome. Those who rated clinically highly had an almost normal pressure distribution with only slightly lower dynamic pressure under the fifth metatarsal and lower pressure/time under hallux. Those with poorer outcomes had shorter foot ground contact, lower pressure under heel and hallux plus increased pressure under the fifth metatarsal head. They used pedobarographic results combined with clinical outcomes to determine the best surgical regime. Hutchison et al. [6] showed that patients can compensate and therefore redistribute the pressure across the foot when standing, but this may not be possible while walking. This suggests that a static examination may not be representative of changes, which occur on exercise. Hutchins et al. [16] demonstrated that static pressure deformities were not related to gait, range of movement and subjective opinion. However, they did detect subtle abnormalities in 35% of treated patients. It is, therefore, agreed that dynamic data can be more valuable. In a study of corrected feet, Hutchinson et al. [6] claimed that alterations in pressure distribution can lead to pain, ulcers and callosities. Hutchinson et al. [6] concluded that pedobarography is a good technique to assess patients who complain of symptoms that can not be explained by clinical examination. Abboud and Swanson [4] demonstrated that foot pressure analysis could detect, in a patient who was about to have surgery, a deformity that would be better treated conservatively by the use of orthoses. Therefore, foot pressure investigation has been used to confirm the presence of the deformity and determine necessary treatment.
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Liu and Thometz [30] concluded that, for a total assessment it is advantageous to have clinical, radiographic and biomechanical data. Hee et al. [7] concluded that pedobarography can provide objective assessments of persistent and subtle deformities in corrected clubfeet. 2.4.2. Gait analysis Gait analysis involves examination and investigation of human locomotion and is commonly used by both clinicians and athletes/coaches to enhance human movement. Foot problems can affect the function of the limb and result in an abnormal gait. Simple observation of gait is unreliable because it is hard to quantify observations and comparison by memory is poor. Gait analysis provides easy, quantitative, objective and dynamic results. Abboud [1] stated that abnormalities at the interface between the foot and ground occur in the majority of disorders of the foot resulting in further problems. Currently gait analysis is used to assess various paediatric conditions. Asperheim et al. [31] asserted that it plays a vital role in the management of children with cerebral palsy. The technique involves systematic measurement, description and assessment of human locomotion particularly temporal and spatial characteristics, orientation of limb segments, ground force reaction and electromyographic data. Parameters are often compared, either to the other foot, or with a control group. Data can be used to support the clinical findings by identifying and quantifying the presence of physiological and pathological gait function. Gait analysis can aid selection and evaluation of treatment. Gait analysis could be used as an adjuvant to foot pressure analysis and clinical assessment, but is less suitable as a stand-alone assessment technique, because it is not suitable in very young children who cannot yet walk or exhibit an adult pattern gait [31]. The aetiology of an abnormal gait is multifactorial. Apart from other musculoskeletal problems changes in height and age can alter gait when assessment is over a long period of time. Ageing and growth result in an increase in height, which can alter gait parameters. Beck et al. [32] showed that an adult gait pattern was achieved by age 4–5 years. A number of studies have been carried out to identify the gait abnormalities in children with treated clubfoot. However, none has determined the significance of these specific changes in terms of signs of correction or relapse. Karol et al. [33] and Hee et al. [7] demonstrated no significant changes in velocity, cadence, stride length, stance phase between normal, unilateral and bilateral clubfoot groups (post-operative). However, Thometz and Eberle [34] demonstrated lower velocity and stride length in children with treated clubfeet. Tareco et al. [10] established that foot progression was significantly different between clubfoot patients (3.6◦ of in-toeing) and the control group (5◦ of out-toeing). An internal foot progression angle was also seen by [13,33] (inward rotation of 4◦ ). Sawatzky et al. [35] showed decreased vertical force at heel strike with a more
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internal vertical moment impulse where normal children display a greater external moment impulse. Thometz and Eberle [34] demonstrated decreased transfer of pressure to the forefoot and out of phase tibialis anterior activity. Widhe and Berggren [13] found lower maximum reaction and acceleration forces in affected limb when compared to the contralateral limb. Karol et al. [33] demonstrated disturbed ankle sagittal-plane kinematics. They also found genu-valgum and knee hyperextension, plus weakness of plantarflexion, quadriceps, hamstrings and gastrosoleus. They attributed the latter to Achilles tendon lengthening. Thometz and Eberle [34] also demonstrated an abnormality in force vectors particularly at the knee. Few conclusions have been made regarding the abnormalities seen and their importance. Thometz and Eberle [34] deduced that, despite patients having clinical and radiological correction, gait analysis detected residual abnormalities. Asperheim et al. [31] found that gait analysis provides valuable information in all cases to support further management. Karol et al. [32] predicted that the abnormalities demonstrated will cause degenerative changes and functional limitations in later life. Widhe and Berggren [13] stated that the combination of data from gait analysis and foot pressure studies add objective and important information in the assessment of treated feet. This opinion is echoed by Hee et al. [7] who opined that, together, they could identify more subtle abnormalities.
3. Conclusion Assessment plays a vital role in the management of clubfoot but current methods (clinical, functional and radiological) are sub-optimal. Limited research has been undertaken assessing the role of biomechanical assessment. Both foot pressure and gait analysis have been shown to be objective, functional and quantitative methods of assessment and can provide valuable information to aid the assessment of the deformity and management. It is thought that in the future, new classification criteria will incorporate certain aspects of gait and pedobarographic data to allow complete assessment.
References [1] Abboud RJ. Relevant foot biomechanics. Curr Orthop 2002;16:165– 79. [2] Harrold AJ, Walker CJ. Treatment and prognosis in congenital clubfoot. J Bone Joint Surg 1983;65B:8–11. [3] Uglow MG, Clarke NM. The functional outcome of staged surgery for the correction of Talipes Equinovarus. J Pediatr Orthop 2000;20:517– 23. [4] Abboud RJ, Swanson AJ. The role of foot pressure analysis in the assessment of relapsed clubfeet. J Bone Joint Surg 2000;82B(Suppl III):204.
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[5] Fopma E, Abboud RJ, Macnicol MF. Correlation of a clinical outcome measurement to biomechanical assessment in surgically treated clubfeet. Presented at BOA congress 2002. [6] Hutchinson RJ, Betts RP, Donnan LT, Saleh M. Assessment of Ilizarov correction of clubfoot deformity using pedobarography: a preliminary report. J Bone Surg 2001;83B:1041–5. [7] Hee HT, Lee EH, Lee GSM. Gait and pedobarographic patterns of surgically treated clubfeet. J Foot Ankle Surg 2001;40:287–94. [8] Centel T, Bagatur AE, Ogut T, Aksu T. Comparison of soft tissue release methods in idiopathic clubfoot. J Pediatr Orthop 2000;20:648– 51. [9] Simons GW. Analytical radiography of clubfeet. J Bone Joint Surg 1977;59B:485–9. [10] Tareco J, Sala DA, Scher DM, Lehman WB, Feldman DS. Percutaneous fixation in clubfoot surgery: a radiographic and gait study. J Pediatr Orthop 2002;B11:139–42. [11] Laaveg SJ, Ponseti IV. Long-term results of treatment of congenital clubfoot. J Bone Joint Surg 1980;62A:23–31. [12] Wynne Davies R. Talipes Equinovarus—a review of 84 cases after completion of treatment. J Bone Joint Surg 1964;46B:464–76. [13] Widhe T, Berggren L. Gait analysis and dynamic foot pressure in the assessment of treated clubfoot. Foot Ankle Int 1994;15:186–90. [14] Cooper DM, Dietz FR. Treatment of idiopathic clubfoot. J Bone Joint Surg 1995;77A:1477–89. [15] Roye BD, Vitale MG, Gelijns AC, Roye DP. Patient-based outcomes after clubfoot surgery. J Pediatr Orthop 2001;21:42–9. [16] Hutchins PM, Foster BK, Paterson DC, Cole EA. Long-term results of early surgical release in clubfeet. J Bone Joint Surg 1985;67B:701– 99. [17] Macnicol MF, Nadeem RD, Forness M. Functional results of surgical treatment in congenital Talipes Equinovarus (Clubfoot): a comparison of outcome measures. J Pediatr Orthop 2000;B9:285–92. [18] Turco VJ. Current problems in orthopaedics: clubfoot. Churchill Livingston, 1981. [19] Wallander H, Hansson G, Tjernstrom B. Correction of persistent clubfoot deformities with the Ilizarov external fixator—experience in 10 previously operated feet followed for 2-5 years. Acta Orthop Scand 1996;67:283–7. [20] Huang YT, Lei W, Zhao L, Wang J. The treatment of congenital clubfoot by opertaion to correct deformity and achieve dynamic muscle balance. J Bone Joint Surg 1999;81B:858–62.
[21] Aronson J, Puskarich CL. Deformity and disability from treated clubfoot. J Pediatr Orthop 1990;10:109–19. [22] Abboud RJ. Design of an insole measuring foot pressure distribution. MSc biomedical and rehabilitation engineering. University of Dundee; 1989. [23] Bowen TR, Miller F, Castagno P, Richards J, Lipton G. A method of dynamic foot-pressure measurement for the evaluation of paediatric orthopaedic foot deformities. J Paediatr Orthop 1998;18:789–93. [24] Abboud RJ. Sports medicine SSM module guide. University of Dundee, 2001. [25] Henning EM, Staats A, Rosenbaum D. Plantar pressure distribution patterns of young school children in comparison to adults. Foot Ankle Int 1994;15:35–40. [26] Henning EM, Rosenbaum D. Pressure distribution patterns under the feet in comparison to adults. Foot Ankle 1991;11:306–11. [27] Kumar K. The role of footprints in the management of clubfeet. Clin Orthop Relat Res 1979;140:32–6. [28] Dall G. Dynamic assessment of the load distribution on the plantar surface of the foot using the University of Cape Town Walkway and its clinical applications. Foot Ankle 1984;4:286–91. [29] Brand RA, Laaveg SJ, Crowninshield RD, Ponseti IV. The center of pressure path in treated clubfeet. Clin Orthop Relat Res 1981;160: 43–7. [30] Liu X, Thometz J. Predictors of dynamic foot function in idiopathic clubfoot by foot radiographs. Clin Biomech 2001;16:843. [31] Asperheim MS, Moore C, Carroll NC, Dias L. Evaluation of residual clubfoot deformity using gait analysis. J Pediatr Orthop B 1995;4:49– 54. [32] Beck RJ, Andriacchi TP, Kuo KN, Fermier RW, Galante JO. Changes in gait patterns in growing children. J Bone Joint Surg 1981;63A: 1452–7. [33] Karol LA, Concha MC, Johnston CE. Gait analysis and muscle strength in children with surgically treated clubfeet. J Pediatr Orthop 1997;17:790–5. [34] Thometz J, Eberle C. Gait analysis in surgically treated clubfeet. Pediatr Orthop Soc N Am 1990;14:289. [35] Sawatzky BJ, Sanderson DJ, Beauchamp RD, Outerbridge AR. Ground reaction forces in gait in children with clubfeet—a preliminary study. Gait Posture 1994;2:123–7.
Review
The need for biomechanical evaluation in the assessment of clubfoot F. Herd a , M. Macnicol b , R.J. Abboud a,∗ a
Institute of Motion Analysis and Research (IMAR), Department of Orthopaedics and Trauma Surgery, T.O.R.T. Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK b Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 1LF, UK Received 1 September 2003; accepted 9 December 2003
Abstract Clubfoot is a complex deformity found in one in a thousand children. It frequently causes disability—either from the original deformity or because of secondary conditions and problems associated with treatment. The management remains varied and controversial. Currently, mixtures of different methods are used to assess the severity of the deformity. However, none is ideal. Biomechanical assessment involves the evaluation of forces and motion of the musculoskeletal system and includes the analysis of foot pressure distribution and gait parameters. The aim of this article is to discuss the various assessment techniques available and demonstrate the need for, and advantages of, biomechanical assessment. © 2004 Elsevier Ltd. All rights reserved. Keywords: Clubfoot; Assessment; Foot pressure; Gait analysis; Biomechanics
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Assessment of clubfoot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Clinical assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Radiological assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Functional. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4. Biomechanical assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1. Foot pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2. Giat analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. 2.
1. Introduction Clubfoot encompasses a spectrum of foot deformity that frequently results in long-term deformity and disability and presents considerable challenges to the orthopaedic surgeon. The controversy exists because the exact pathogenesis and pathological anatomy remain unknown, there is no agreed method of assessment and no uniform management. Assessment is essential for the prescription and evaluation of treatment, as well as predicting prognosis [1]. Cur∗ Corresponding author. Tel.: +44-1382-496332; fax: +44-1382-496200. E-mail address: [email protected] (R.J. Abboud).
0958-2592/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.foot.2003.12.004
72 72 73 73 73 74 74 75 75 75
rently, combinations of clinical, functional and radiological techniques are used. These are subjective and hard to repeat and often do not show important or subtle changes. Consequently it is hard to evaluate the outcome of each type of treatment objectively.
2. Assessment of clubfoot Assessment provides a method of classifying the severity of the original deformity and evaluating the success of treatment. Previous research has indicated that the outcome of treatment is related to the initial severity of the deformity [2,3] and therefore, classification is used as a guide to prog-
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nosis. Quantitative data allows comparison facilitating monitoring of success of treatment and progression of deformity or relapse. Detection of subtle signs of deformity would allow earlier, simpler management and prevent the progression of severe and permanent damage. This includes secondary conditions such as osteoarthritis, which could cause further disability. An enhanced system of classification would ensure that all children receive the appropriate management, i.e. further surgery and/or orthotic support. This would provide them with the best possible function of the limb and, hence, quality of life now and in the future. The ability to objectively evaluate each type of treatment would also allow comparison of techniques, which might result in the formulation of a universal management strategy. There is no universal method for the assessment of clubfoot. A variety of techniques are used including clinical, functional and radiological investigations. Currently, a mixture of subjective and objective methods is used to assess the clubfoot [4,5]. 2.1. Clinical assessment Clinical parameters make up the most common form of assessment and involve measuring the extent of the fixed deformity, its rigidity and reducibility. Other aspects include the range of movement, bimalleolar angle, presence of creases (medial and posterior), calf wasting and foot size, strength and whether pressure on first ray causes subluxation (telescoping). Clinical measurements focus on cosmetic appearance and are often static. Most of this data is subjective, affected by interobserver error and hard to repeat [6]. Visual interpretation of outcome is poor. Both Hee et al. [6] and Hutichson et al. [7] surmised that what appeared to be a cosmetically good foot did not necessarily have a good function. Numerous classification/assessment systems have been published, each incorporating a different set of parameters with varied weighting. This makes comparison of results difficult. Cental et al. [8] stated that in young children the ratio of soft tissue to bone is at its maximum, thus any management decision based on clinical appearance alone would be misleading hence identifying the need for another method of examination. Photography and cinematography show visual changes but cannot provide objective quantitative data [4]. 2.2. Radiological assessment Radiographs define the precise anatomical relationship of joints. Simons [9] suggested studying the talocalcaneal index—derived by adding the lateral and antero-posterior angles together. He stated that a normal individual had an index above 50◦ but this was much lower in the clubfoot patient group. Successful correction can result in an index over 50. However, most post-operative patients show a lower index
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[10], Laveg and Ponseti [11] found that the lateral talocalcaneal angle correlated well with functional rating and patient satisfaction. However, Wynne Davis [12] questioned the use of radiological outcomes as early as 1964. Inter alia, several studies [3,13–15] did not correlate well with clinical parameters and could not be used to predict outcome. Hutchins et al. [16] maintained that anatomical normality is never achieved, thus an assessment technique looking at anatomical realignment is poor. Problems with radiological measurements include repeatability and difficulty in positioning the foot correctly [17]. In addition, conventional radiography cannot give reliable information at a young age due to lack of ossification of bones. Furthermore, the ossified nucleus has been shown to appear later in children with CTEV [18]. Therefore, it is not an ideal method of assessment. 2.3. Functional Functional assessment examines the ability to carry out daily tasks and incorporates the patient’s subjective opinion regarding outcome and disability. Activity levels, walking, sporting capability, presence of a limp, pain, shoes, appearance and satisfaction are all considered. Pre-operative assessment is difficult if the child is still young with limited mobility. Repeatability is poor [6] and is subjective, with answers depending on mood of patient and the manner in which the questions are asked. Often the patient can misinterpret the point or the interviewer misconstrue the answer. With young children parents may have to answer by proxy and the age of child could affect the answers given. However, this is probably the area most important to the patient. Roye et al. [15] developed a disease specific index (DSI) that looked at the function of the limb and the satisfaction of the parent/child. They found a relationship between some clinical parameters and functional outcome. For example, patients with increased heel varus were more likely to complain of decreased satisfaction and poor running ability. None of the above methods are objective or completely reliable thus the search continues to identify a new technique. Therefore, there is a need for an objective method of assessment to produce data which can assess initial severity, predict prognosis, determine necessary treatment, evaluate outcome and detect relapse or poor correction [1]. Wallander et al. [19] concluded that currently there is no ideal rating system, but one which pays more attention to function, such as gait and foot pressure, rather than appearance alone would be useful. The ideal form of assessment would produce objective, quantitative and functional data as well as being simple, reproducible, reliable, cheap and safe. A corrected foot is plantigrade, functional and pain free (inter alia [14,20]), but assessing this is difficult. It is essential for the clinician to understand the changes in the foot under dynamic activity [6]. There is also some discord over which features are the most important, for example, does excellent function override anatomical imperfections? Perhaps a mild equinus
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deformity with stronger plantarflexors is more functional than a weaker plantigrade foot [21]. 2.4. Biomechanical assessment Foot deformities interfere with the ability to walk and induce symptoms because of abnormal distribution of load under the plantar surface of the foot. Therefore, there is a need to assess the foot biomechanically [1], including the study of kinetics (force and motion) and kinematics (motion irrespective of force). This enables evaluation of foot function at time of contact with floor, plus analysis of forces and their effects on anatomical structures. Hee et al. [7] stated that, although corrected clubfeet look good and function well; more objective analysis revealed that the biomechanical functions of the foot were not entirely normal. Research has been undertaken involving the use of foot pressure and gait analysis to provide objective, functional and biomechanical data for evaluation of clubfeet. Previous work has focused on the identification of abnormalities present in children with clubfeet. However, no agreement has been reached on the specific role that these techniques have to offer. For example, there is the question of whether they can be used as a method of assessing initial severity and prognosis or to determine and evaluate treatment. 2.4.1. Foot pressure In healthy normal individuals, plantar pressure is distributed under the load-bearing areas such as the heel, metatarsal heads and phalanges [22]. Abnormalities in either structure or function of the foot can alter this pattern and lead to areas of dangerously abnormal pressure where callosities or other injury can occur. Simple observation of the foot alone could mislead the clinician, but analysis of plantar pressure can assist anatomical inspection. Over the last 20 years many techniques for the measurement of pressure distribution underneath the plantar surface of the foot have arisen, although none fulfils the ideal characteristics [1]. The data produced yields objective qualitative and quantitative information about foot structure and function. Foot pressure can be static (standing), or dynamic (measuring pressures exerted during the gait cycle, for example, whilst walking). Currently, it is used in many specialities of medicine, for both assessment and post-operative review, and in sport. Bowen et al. [23] claimed that foot pressure data is a diagnostic method to measure the severity of any foot deformity and can quantify the changes resulting from surgery, hence fulfilling some of the criteria identified above. These techniques have already found a place in the assessment of rheumatoid arthritis, cerebral palsy and diabetes mellitus [24]. However, foot pressure is also affected by age, size, weight and gait velocity [25,26]. Therefore, when assessing children over a number of years the effects of growth must be taken into account. The lack of literature defining foot pressure in normal children makes evaluation more difficult.
Recent literature review shows the research areas involving the use of foot pressure analysis. The deformity can be analyzed simply by looking at the shape and pattern of the print. Kumar [27] used serial inked footprints to demonstrate the progression of the deformity and show the need for surgical management. No one has evaluated the use of foot pressure in assessing the original untreated deformity. Assessments of children with a secondary equinovarus reported a lack of heel pressure and increased forefoot loading, particularly laterally [28]. Hutchinson et al. [6] found that dynamic peak pressure shifted medially and posteriorly after surgery showing correction of equinovarus. However, Hee et al. [7] demonstrated that the hindfoot of the treated clubfoot population bears less pressure than forefoot when standing and Aronson and Puskarich [21] found increased pressure under the fifth metatarsal head in their treated group, both of which suggest some residual deformity. Brand et al. [29] correlated a functional rating with the centre of pressure but concluded that the centre of pressure was not sensitive enough to distinguish between normal and affected feet. Cooper and Dietz [14] and Huang et al. [20] found that foot pressure data can distinguish between those with an excellent/good clinical outcome and those with poor/fair outcome. Those who rated clinically highly had an almost normal pressure distribution with only slightly lower dynamic pressure under the fifth metatarsal and lower pressure/time under hallux. Those with poorer outcomes had shorter foot ground contact, lower pressure under heel and hallux plus increased pressure under the fifth metatarsal head. They used pedobarographic results combined with clinical outcomes to determine the best surgical regime. Hutchison et al. [6] showed that patients can compensate and therefore redistribute the pressure across the foot when standing, but this may not be possible while walking. This suggests that a static examination may not be representative of changes, which occur on exercise. Hutchins et al. [16] demonstrated that static pressure deformities were not related to gait, range of movement and subjective opinion. However, they did detect subtle abnormalities in 35% of treated patients. It is, therefore, agreed that dynamic data can be more valuable. In a study of corrected feet, Hutchinson et al. [6] claimed that alterations in pressure distribution can lead to pain, ulcers and callosities. Hutchinson et al. [6] concluded that pedobarography is a good technique to assess patients who complain of symptoms that can not be explained by clinical examination. Abboud and Swanson [4] demonstrated that foot pressure analysis could detect, in a patient who was about to have surgery, a deformity that would be better treated conservatively by the use of orthoses. Therefore, foot pressure investigation has been used to confirm the presence of the deformity and determine necessary treatment.
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Liu and Thometz [30] concluded that, for a total assessment it is advantageous to have clinical, radiographic and biomechanical data. Hee et al. [7] concluded that pedobarography can provide objective assessments of persistent and subtle deformities in corrected clubfeet. 2.4.2. Gait analysis Gait analysis involves examination and investigation of human locomotion and is commonly used by both clinicians and athletes/coaches to enhance human movement. Foot problems can affect the function of the limb and result in an abnormal gait. Simple observation of gait is unreliable because it is hard to quantify observations and comparison by memory is poor. Gait analysis provides easy, quantitative, objective and dynamic results. Abboud [1] stated that abnormalities at the interface between the foot and ground occur in the majority of disorders of the foot resulting in further problems. Currently gait analysis is used to assess various paediatric conditions. Asperheim et al. [31] asserted that it plays a vital role in the management of children with cerebral palsy. The technique involves systematic measurement, description and assessment of human locomotion particularly temporal and spatial characteristics, orientation of limb segments, ground force reaction and electromyographic data. Parameters are often compared, either to the other foot, or with a control group. Data can be used to support the clinical findings by identifying and quantifying the presence of physiological and pathological gait function. Gait analysis can aid selection and evaluation of treatment. Gait analysis could be used as an adjuvant to foot pressure analysis and clinical assessment, but is less suitable as a stand-alone assessment technique, because it is not suitable in very young children who cannot yet walk or exhibit an adult pattern gait [31]. The aetiology of an abnormal gait is multifactorial. Apart from other musculoskeletal problems changes in height and age can alter gait when assessment is over a long period of time. Ageing and growth result in an increase in height, which can alter gait parameters. Beck et al. [32] showed that an adult gait pattern was achieved by age 4–5 years. A number of studies have been carried out to identify the gait abnormalities in children with treated clubfoot. However, none has determined the significance of these specific changes in terms of signs of correction or relapse. Karol et al. [33] and Hee et al. [7] demonstrated no significant changes in velocity, cadence, stride length, stance phase between normal, unilateral and bilateral clubfoot groups (post-operative). However, Thometz and Eberle [34] demonstrated lower velocity and stride length in children with treated clubfeet. Tareco et al. [10] established that foot progression was significantly different between clubfoot patients (3.6◦ of in-toeing) and the control group (5◦ of out-toeing). An internal foot progression angle was also seen by [13,33] (inward rotation of 4◦ ). Sawatzky et al. [35] showed decreased vertical force at heel strike with a more
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internal vertical moment impulse where normal children display a greater external moment impulse. Thometz and Eberle [34] demonstrated decreased transfer of pressure to the forefoot and out of phase tibialis anterior activity. Widhe and Berggren [13] found lower maximum reaction and acceleration forces in affected limb when compared to the contralateral limb. Karol et al. [33] demonstrated disturbed ankle sagittal-plane kinematics. They also found genu-valgum and knee hyperextension, plus weakness of plantarflexion, quadriceps, hamstrings and gastrosoleus. They attributed the latter to Achilles tendon lengthening. Thometz and Eberle [34] also demonstrated an abnormality in force vectors particularly at the knee. Few conclusions have been made regarding the abnormalities seen and their importance. Thometz and Eberle [34] deduced that, despite patients having clinical and radiological correction, gait analysis detected residual abnormalities. Asperheim et al. [31] found that gait analysis provides valuable information in all cases to support further management. Karol et al. [32] predicted that the abnormalities demonstrated will cause degenerative changes and functional limitations in later life. Widhe and Berggren [13] stated that the combination of data from gait analysis and foot pressure studies add objective and important information in the assessment of treated feet. This opinion is echoed by Hee et al. [7] who opined that, together, they could identify more subtle abnormalities.
3. Conclusion Assessment plays a vital role in the management of clubfoot but current methods (clinical, functional and radiological) are sub-optimal. Limited research has been undertaken assessing the role of biomechanical assessment. Both foot pressure and gait analysis have been shown to be objective, functional and quantitative methods of assessment and can provide valuable information to aid the assessment of the deformity and management. It is thought that in the future, new classification criteria will incorporate certain aspects of gait and pedobarographic data to allow complete assessment.
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