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The coxa pedis
EUR J FOOT ANKLE SURG 1994;1:67-74
The coxa pedis GIACOMO PISANI
The talo-caicaneal-navicular j o i n t is a n a l o g i c a l l y referable f r o m a n a n a t o m i c (enarthrosic differentiation), evolutive (skeletal rotations) and maiformative (dysplasias) p o i n t o f view to the hip. The concept and definition o f " c o x a p e d i s " is r e f e r r e d t o the just mentioned. The proximal and distal enarthrosic differentiation of the inferior limb, with interposed joint representes by the knee, is the b i o m e c h a n i c presupposition to the rotatory mechanism ( h o r i z o n t a l p l a n e ) indispensable to starting off the stabilization of the l i m b itself in a l o a d bearing phase (closed k i n e t i c s c h a i n ) and the succession of intercurrent mechanism in the frontal p l a n e (lateral t r a n s l a t i o n o f t h e l o a d i n starting load bearing phase) and in the sagittal p l a n e ( o s c i l l a t i n g phase). KEY WORDS: C o x a p e d i s .
T he "coxa-pedis" corresponds to the "talo-calI. caneo-naVicular joint ' ' described by Testut and Jacob 1 as an enarthrosis in which it is possible to define (Fig. 1A, B) an epiphysis represented by the head and the neck of the talus and an osteo-fibrocartilaginous cotyloid cavity (acetabulum) by which the constitution converge, as skeletal elements, the posterior articular surface of the navicular and the calcaneal surface (or surfaces: sustentaculum tall, anterior proces of the calcaneus) of the anterior subtalar joint. Between the articular surfaces (calcaneus, navicular) the cotyloid cavity is completed by a gleReceived June 6, 1994 Accepted for publication September 29, 1994.
Address reprint requests to: Giacomo Pisani, Casa di Cura Fornaca, Corso Vittorio Ernanuele II, 91 - 10100 Torino (Italy).
Vol. 1 - No. 2-3
From the "Prof. G. Pisani'" Center of Foot Surgery, "'Fornaca di Sessant'" Clinic, Turin, Italy
noid structure superficially reinforced by the spring ligament (Fig. 1C). The spring ligament is a reinforcing fascicle of the talo-calcaneo-navicular joint capsula: beginning at the base of the antero-medial outline of the sustentaculum tali, it inserts itself distally to the medial tubercule and to the corresponding postero-inferior surface of the navicular. As a reinforcing fascicle it is not a well individualized anatomic formation and is therefore only artificially dissociable by the capsular apparatus. It corresponds to the bottom of the cotyloid cavity and subtends a real glenoid structure in an articular correlation (Fig. 1D) with the inferomedial head surfaces of the talus lying between the navicular and calcaneal articular surfaces. From an anatomic point of view, the research carried out by Volpe, Marconi, Pozza and Spizzo are of interest. The Authors point out, and document, the mosaic structure of the acetabulum with skeletal, ligamentous and fibro-cartilaginous components and an adipose flock at the centre of the cavity. The fibro-cartilaginous structure, that fan-shaped subtends the talus head, leans above the chiasma established by the crossing of the digitorum and hallucis longus tendons and is reinforced in its distomedial portion by the posterior tibial tendon. Both the in-
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THE COXA PEDIS
Fig. 1 A-D.--(A) Skeletal articular components of the "coxa pedis". (B) Dried preparation of the "cotile pedis". (C) Fresch preparation of the "coxa pedis" (by Volpe, Marconi, Pozza, Spizzo). (D) Glenoid cavity articular surface in a dissected specimen of a new-born (by Giannini and Bachechi) and its correlation with the corresponding talar epiphysary articular surface.
Fig. 2.--In a precocious embryonal phase (llst-12ft week) the talonavicular and anterior subtalar joint are clearly differentiated in an only articular structure with enarthrosis morphological characteristics (obs. De Palma, Coletti, Santucci, Tulli),
68
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
THE COXA PEDIS
PISANI
Pig. 3 A - D . - - ( A ) Picture of anatomic preparation of the talo-calcaneo-navicular joint in a newborn ("coxa pedis"). (B) The same picture turned at 180 ° in hip position: evident anatomic analogy between the two proximal and distal enarthrosic structures of the inferior limb (by Giannini and Bachechi). (C) Histologic section o f the foot o f a foetus, hearer o f congenital club-foot: the sustentaculum tall is almost attached to the navicular while the head o f the talus is inclined laterally to these two formations; the corresponding space is missing at the base of the "cotile pedis" and this corresponds to the operating reports o f sustentaculum-navicular attachment with a reduction of the cotyloid cavity, in the residual part replaced by a thick fibrous m a g m a (by Ricciardi Pollini). (D) Vertical talus: surgical anatomo-pathological view. The head of the talus is o f immediate valuation, when the posterior tibial tendon is only just moved downwards; protruding between the sustentaculum tall and navicular, it is only just held by a thin fibrous bottom without a glenoidal appearance.
termediate fibres of the deltoid ligament that insert themselves to the sustentaculum tali and the recurrent navicular fascicle of the tibial posterior tendon are elements of passive reinforcement of the spring ligament. From the external side the cotyloid cavity is completed by the calcaneo-navicular fascicle of the " Y " or Chopart ligament. The presence moreover, of proprioceptive corpuscles in the spring ligament makes us think of a function also receptive, cybernetic, o f the cotyloid pedis.
Vol. 1 - No. 2-3
In precocious embryonal phases (16th-17th week; Fig. 2) the talus-navicular and anterior subtalar joints are clearly differentiated in an only articular structure of an enarthrosis morphologic characteristic) The concept and the name "cotile pedis" are not new to the anatomists; in literature they are referred to McConaill. With a vaster significance "'coxapedis'" defines 4 the particular functional significance o f a structure that by anatomic, evolutive and clinical data can be
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
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PISANI
THE COXA PEDIS
analogically compared to the hip: the talar "epiphysis", articulated in the "cotyloid cavity", transmits variedly to the foot the load stress directing them by the amount of directional thrust generated by gravity 50* 150* and by the reaction to the supports, in correlation also to the axial, torsional and rotatory oversegmentary solicitations. 5 It is in this mechanism o f force .i.25o . . . . . . . directionally that the foot, structure for a viable load, -15" is integrated with the hip and knee in the more complex for a variable load structure represented by the inferior limb. 6 7 The anatomic differentiation in the enarthrosis o f Fig. 4 A, B . - - T h e detorsions o f the talar and femoral neck are opposed by direction, but overlapping, evolutively, by the respective angular the "coxa pedis" is to be considered with a biovalues: starting with apoproximative values from birth o f 50 ° o f talar mechanical significance: while the proximal "coxa" declination (retroversion) and of 40 ° of femoral declination (antiversion), we reach the definitive average values o f 25 ° for the former around 6-7 (hip) permitted by its enarthrosic structuring the need years o f age and for the latter around 12-14 years. o f hip movement required, the enarthrosic structurINTERNAL FEMORAL DETORSION 25* (-40°~15 °)
•
•
-
.
.
.
.
.
.
.
.
.
.
.
EXTERNAL TALAR D E T O R S I O N 25* ( + 5 0 ° ~ 2 5 °
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.
YEARS
| 5
ADULT
.
i
:
:
:
:
:
:
I
15
0
0
\
cZ]
Fig. 5 . - - M a l f o r m a t i v e correspondence between the hip and the " c o x a pedis": luxation (above) and protrusion (below) representing the extreme o f dysplasia of which the intermediate in sub-luxation and pre-luxation dysplasias by the hip that corrects an initial antiversion, in sub-protrusion and pre-protrusion (evolutive valgus foot in children) by the " c o x a pedis" that corrects an initial retroversion.
70
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
THE COXA PEDIS
PISANI
ing of the "coxa pedis", restricted in its motion by the subtalar joint restraints, allows to modulate to the stable foot the directionality of the forces.S As already mentioned, one has to take into account the completion of the bearing phase of two enarthrosis that are in a contemporary "instantaneous functional arthrodesis."
Anatomic correspondence From an anatomic point of view, the morphological analogies of the neck and head of the talus with the proximal epiphysis of the femur are evident, in particular considering the talus blocked in the malleolar princes by the stabilizing action of the posterior muscles of the leg, a condition in which it becomes functionally "leg bone". If we imagine the carrying out of a frontal resection through the hip and a sagittal resection through the "coxa pedis" and if we consider the talus as bone of the leg, the os ilium-pubis profiles of the proximal acetabulum has analogic correspondence in the calcaneo-navicular profiles of the distal acetabulum and the interposed acetabular fossa of the first corresponds to the fibro-glenoid component of the second. The head and neck of the femur correspond to the talus head and neck, femoral diaphysis to the tibial diaphysis. And observing on the proximal section the greater and lesser trochanter, these have projective distal correspondence in the fibular and tibial malleoli. This anatomic correspondence is particularly significant in initial development phases. The anatomic documentation collected by Giannini and Bachechi on the new-born child (Fig. 3A, B) is of interest.
Evolutive correspondence From an evolutive point of view, considering the detorsion of the talar and the femoral neck (Fig. 4), they are opposite in direction, but overlapping by their relative angular values; this is to maintain the normal opening of the functional angle of declination of the talus as regards the gait direction. Starting from the approximate values from birth of 5 0 ° talar declination (retroversion) and a 40 ° femoral declination (anteversion), we reach the definitive aver-
Vol. l - No. 2-3
Fig. 6.--Unilateral luxation o f the " c o x a pedis" in a 6 year old child: the epiphysis, hixated above and externally, does not have any correlation of congruity with the "cotile pedis"; this appears reduced by hypertrophy and convexity of the posterior talar surface. The results, comparatively with the normal counter-lateral, reproposes the pathologic anato m y o f the luxated hip.
age value of 25 ° for the former towards 6-7 years of age and 15 ° for the latter towards 12-14 years. 6 9 It we imagine overturning the foot anteriorly on the hip the angular values of torsion, and their detorsional moments, also become overlapping in direction. As Volpi e t al. rightly confirm, to correlate the variations in which the retroversion angle of the talus and antiversion of the femur go towards, really means checking that which is the trend of the torsion on a transvers plane of the inferior limb during growth.
Malformative correspondence As regards the malformative pathology (Fig. 5), the dislocation and protrusion of the hip are known as the extreme dysplasias among those which are included the intermediate as that are the subluxation
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
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THE COXA PEDIS
Fig. 7 A, B.-- The three components of the deformity (equine, supination, adduction) in the club-foot in new-born. The talar epiphysis is valued clinically sub-luxated dorsally and externally and is notable by surgical treatment its reduction with a cotyloideal lysis.
Fig. 8.--"Rocking shape" apsect of the foot in the congenital vertical talus. The talar epiphysis is valued, clinically, protruding down and medially and is notable, by surgical treatment, its reduction with a cotyloid cavity stabilization (4 year old child).
72
Fig. 9 A, B.--The dysplastic characteristics of the "coxa pedis" in the club-foot (A: luxation) and in the congenital vertical talus (B: protrusion) are well definable radiographically.
and the preluxation; corresponding to the " c o x a pedis" we can define intermediate dysplasias (evolutive valgus foot in children) included between the two extremes represented by the expressed luxation o f the congenital club-foot and by the protrusion corresponding to the vertical talus. 3 to 11 In exceptional cases of a congenital dislocation o f the talus (Fig. 6) in which the head of the talus has no correlation of congruency with the cotyloid cavity, it appears radiographically deformes and stunk with h y p e r t r o p h y and posterior convexity of the navicular correspodingly to the anatomo-radiographic image o f the hip openly dislocated. On the contrary, in the talar protrusion, in which the more manifest result is represented by the congenital rigidus flat foot, the head and the neck o f the talus are sunken in the cotyloid cavity. In this case more enlarged while the navicular, dorsally hypertrofic, is almost in contact with the trochlea.
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
THE COXA PEDIS
PISANI
Fig. 10 A - D . - - X - r a y o f degenerative-structural pathology o f an arthrosic type of the "coxa pedis": similarly to the hip, next to the picture essentially definable (A, B), others are definable in the ambit of dysplastic pathology (C, D).
The clinical characteristics of the club-foot are ble also in the newly-born stage and which confirm konwn with the three components in equinus, supi- the characteristics of the cotyloid dysplasia are also nation and adduction (Fig. 7). Equally the clinical known (Fig. 9). characteristics of the congenital vertical talus are The pathological anatomy of the two deformities known (Fig. 8) with its unmistakable "rocking shape" is a confirmation of a common malformative pathoP aspects: it is of importance the fact, clinically, that o g y relatively to the concern of the regional dysplait is possible to value the head of the talus dorsally sia of the coxa pedis. and laterally dislocated in the clubfoot, while it is proRegarding the club-foot documentative is the truded down-ward and medially in the congenital ver- iconography showed by Perugia, Ricciardi Pollini and tical talus. Ippolito at the 61st Congress of the Italiam Society The roentgenographic appearance already defina- of Orthopedy and Traumatology (Milan, September
Vol. t - No. 2-3
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THE COXA PEDIS
30, 1976): in the p h o t o m i c r o g r a p h section o f a foetus's foot (Fig. 3C), a club-foot bearer, the sustentaculum tall is almost joined to the navicular while the head of the talus is arranged laterally to these two formations; the corresponding space is missing at the operating reports o f a sustentaculum-navicular joning with a reduction o f the cotyloid b o t t o m formed, in the residual part, by a thick fibrous magma. We have the contrary in the congenital vertical talus (Fig. 3D): the talus head, operatively, is o f immediate valuation by only just moving the posterior tibial tendon downward: protruding between the sustentaculum tali and the navicular it is only just contained by a thin fibrous b o t t o m without a glenoideal appearance. The anatomo-pathologic analogies between the dysplasia o f the hip and o f the " c o x a p e d i s " reproposed themselves in terms o f treatment: 10-12while in the club-foot the therapeutic p r o b l e m is to reduce the talar epiphysis in the "cotile pedis" exactly the same way as in the luxation coxa congenita, in the congenital vertical talus the problem is to extract the talar epiphysis from the cotyloid cavity from which m o r p h o l o g y and stability have to be re-established. The fact m a y seem not analogous that at the hip level the intermediate dysplasias are more often on a subluxation way, while at the " c o x a pedis" level the protrusion type are more frequent (talar protrusion in the ambit o f evolutive valgus foot in children). The none analogy is only apparent as the detorsions o f the talar and femoral neck are inverted: while the femoral neck, anti-verse, tends to centre itself starting from a subluxation disposition, the talar neck, retr0verse, tends to centre itself starting from a protrusion disposition. It is evident, however, h o w the least dysplasias, more often by an evolutive failure, are more frequently in luxation for the hip and in protrusion for the "cotile pedis". This malformative analogy, which we can define as a system, between hip and " c o x a p e d i s " has collations in not exceptional congenital luxation cases o f the hip associated to the club-foot. The cases o f d u b - f o o t on one hand and vertical talus on the other, are not even exceptional in the same system even if opposite by eccess and defect.
74
In a degenerative pathology ambit (Fig. 10), there is a radiographic correspondence of arthrosic pictures of the " c o x a pedis" with the typical structural lesions concerning the hip at times essential, more often in the context of a degenerative pathology on a dysplasic basis. Riassunto L'articolazione talo-calcaneo-naviculare b analogicamente corrispondente sia da un punto di vista anatomico (differenziazione anartrosica) che evolutivo [torsioni scheletriche patologiche (lussazione, protrusione)] all'articolazione coxofemorale. A questi riferimenti il concetto e la definizione di ~
Coxa pedis.
References 1. Testut L, Jacob O. Trattato di anatomia topografica. Torino: Ed Ital UTET, 1946. 2. Volpe A, Marconi F, Pozza V, Spizzo L. La coxa pedis e le sue caratteristiche anatomiche: analogie e discordanze con la coxa femorale. Clair Piede 1986;X:401. 3. De Palma L, Coletti V, Santucci A, Tulli A. Aspetti embriogenetici della coxa pedis. Archivio Putti 1986;36:113. 4. Pisani G. The concept of the "coxa pedis". Rel XVI Congr. SICOT, Monaco di Baviera, 17 agosto 1987. 5. Pisani G. Biomeccanica clinica del piede. Collana Monografica ~Chirurgia del Piede)~. Torino: Ed Minerva Medica, 1983. 6. Pisani G. La t~coxa pedis~) e i mornenti torsionali astragalici. Chir Piede 1988;XI:35. 7. Pisani G. Function astragalienne et function calcan6enne du membre inf6rieur. Chir Piede 1985;XI:407. 8. Pisani G. Funzione integrata dell'arto inferiore. Giorn Scient di Primavera, Noto, 13-15 rnaggio 1988. 9. Milano L. I momenti torsionali astragalici. Minerva Ortop 1983;XXXIV,6:257. 10. Pisani G. La chirurgia legamentosa nella protrusione della t~coxa pedis)). Relaz Congr Soc Ital di Med e Chir del Piede, Bari, giugno 1982. 11. Pisani G, Milano L. La componente legamentosa nella patologia della ~coxa pedis~. Chit Organi Mov 1982-83;LXVIIl,iv-vi;717. 12. Pisani G, Milano L. Patologia evolutiva del cornplesso legamentoso periastragalico. Chit Piede 1983;VII,3:153.
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
The coxa pedis GIACOMO PISANI
The talo-caicaneal-navicular j o i n t is a n a l o g i c a l l y referable f r o m a n a n a t o m i c (enarthrosic differentiation), evolutive (skeletal rotations) and maiformative (dysplasias) p o i n t o f view to the hip. The concept and definition o f " c o x a p e d i s " is r e f e r r e d t o the just mentioned. The proximal and distal enarthrosic differentiation of the inferior limb, with interposed joint representes by the knee, is the b i o m e c h a n i c presupposition to the rotatory mechanism ( h o r i z o n t a l p l a n e ) indispensable to starting off the stabilization of the l i m b itself in a l o a d bearing phase (closed k i n e t i c s c h a i n ) and the succession of intercurrent mechanism in the frontal p l a n e (lateral t r a n s l a t i o n o f t h e l o a d i n starting load bearing phase) and in the sagittal p l a n e ( o s c i l l a t i n g phase). KEY WORDS: C o x a p e d i s .
T he "coxa-pedis" corresponds to the "talo-calI. caneo-naVicular joint ' ' described by Testut and Jacob 1 as an enarthrosis in which it is possible to define (Fig. 1A, B) an epiphysis represented by the head and the neck of the talus and an osteo-fibrocartilaginous cotyloid cavity (acetabulum) by which the constitution converge, as skeletal elements, the posterior articular surface of the navicular and the calcaneal surface (or surfaces: sustentaculum tall, anterior proces of the calcaneus) of the anterior subtalar joint. Between the articular surfaces (calcaneus, navicular) the cotyloid cavity is completed by a gleReceived June 6, 1994 Accepted for publication September 29, 1994.
Address reprint requests to: Giacomo Pisani, Casa di Cura Fornaca, Corso Vittorio Ernanuele II, 91 - 10100 Torino (Italy).
Vol. 1 - No. 2-3
From the "Prof. G. Pisani'" Center of Foot Surgery, "'Fornaca di Sessant'" Clinic, Turin, Italy
noid structure superficially reinforced by the spring ligament (Fig. 1C). The spring ligament is a reinforcing fascicle of the talo-calcaneo-navicular joint capsula: beginning at the base of the antero-medial outline of the sustentaculum tali, it inserts itself distally to the medial tubercule and to the corresponding postero-inferior surface of the navicular. As a reinforcing fascicle it is not a well individualized anatomic formation and is therefore only artificially dissociable by the capsular apparatus. It corresponds to the bottom of the cotyloid cavity and subtends a real glenoid structure in an articular correlation (Fig. 1D) with the inferomedial head surfaces of the talus lying between the navicular and calcaneal articular surfaces. From an anatomic point of view, the research carried out by Volpe, Marconi, Pozza and Spizzo are of interest. The Authors point out, and document, the mosaic structure of the acetabulum with skeletal, ligamentous and fibro-cartilaginous components and an adipose flock at the centre of the cavity. The fibro-cartilaginous structure, that fan-shaped subtends the talus head, leans above the chiasma established by the crossing of the digitorum and hallucis longus tendons and is reinforced in its distomedial portion by the posterior tibial tendon. Both the in-
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
67
PISANI
THE COXA PEDIS
Fig. 1 A-D.--(A) Skeletal articular components of the "coxa pedis". (B) Dried preparation of the "cotile pedis". (C) Fresch preparation of the "coxa pedis" (by Volpe, Marconi, Pozza, Spizzo). (D) Glenoid cavity articular surface in a dissected specimen of a new-born (by Giannini and Bachechi) and its correlation with the corresponding talar epiphysary articular surface.
Fig. 2.--In a precocious embryonal phase (llst-12ft week) the talonavicular and anterior subtalar joint are clearly differentiated in an only articular structure with enarthrosis morphological characteristics (obs. De Palma, Coletti, Santucci, Tulli),
68
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
THE COXA PEDIS
PISANI
Pig. 3 A - D . - - ( A ) Picture of anatomic preparation of the talo-calcaneo-navicular joint in a newborn ("coxa pedis"). (B) The same picture turned at 180 ° in hip position: evident anatomic analogy between the two proximal and distal enarthrosic structures of the inferior limb (by Giannini and Bachechi). (C) Histologic section o f the foot o f a foetus, hearer o f congenital club-foot: the sustentaculum tall is almost attached to the navicular while the head o f the talus is inclined laterally to these two formations; the corresponding space is missing at the base of the "cotile pedis" and this corresponds to the operating reports o f sustentaculum-navicular attachment with a reduction of the cotyloid cavity, in the residual part replaced by a thick fibrous m a g m a (by Ricciardi Pollini). (D) Vertical talus: surgical anatomo-pathological view. The head of the talus is o f immediate valuation, when the posterior tibial tendon is only just moved downwards; protruding between the sustentaculum tall and navicular, it is only just held by a thin fibrous bottom without a glenoidal appearance.
termediate fibres of the deltoid ligament that insert themselves to the sustentaculum tali and the recurrent navicular fascicle of the tibial posterior tendon are elements of passive reinforcement of the spring ligament. From the external side the cotyloid cavity is completed by the calcaneo-navicular fascicle of the " Y " or Chopart ligament. The presence moreover, of proprioceptive corpuscles in the spring ligament makes us think of a function also receptive, cybernetic, o f the cotyloid pedis.
Vol. 1 - No. 2-3
In precocious embryonal phases (16th-17th week; Fig. 2) the talus-navicular and anterior subtalar joints are clearly differentiated in an only articular structure of an enarthrosis morphologic characteristic) The concept and the name "cotile pedis" are not new to the anatomists; in literature they are referred to McConaill. With a vaster significance "'coxapedis'" defines 4 the particular functional significance o f a structure that by anatomic, evolutive and clinical data can be
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
69
PISANI
THE COXA PEDIS
analogically compared to the hip: the talar "epiphysis", articulated in the "cotyloid cavity", transmits variedly to the foot the load stress directing them by the amount of directional thrust generated by gravity 50* 150* and by the reaction to the supports, in correlation also to the axial, torsional and rotatory oversegmentary solicitations. 5 It is in this mechanism o f force .i.25o . . . . . . . directionally that the foot, structure for a viable load, -15" is integrated with the hip and knee in the more complex for a variable load structure represented by the inferior limb. 6 7 The anatomic differentiation in the enarthrosis o f Fig. 4 A, B . - - T h e detorsions o f the talar and femoral neck are opposed by direction, but overlapping, evolutively, by the respective angular the "coxa pedis" is to be considered with a biovalues: starting with apoproximative values from birth o f 50 ° o f talar mechanical significance: while the proximal "coxa" declination (retroversion) and of 40 ° of femoral declination (antiversion), we reach the definitive average values o f 25 ° for the former around 6-7 (hip) permitted by its enarthrosic structuring the need years o f age and for the latter around 12-14 years. o f hip movement required, the enarthrosic structurINTERNAL FEMORAL DETORSION 25* (-40°~15 °)
•
•
-
.
.
.
.
.
.
.
.
.
.
.
EXTERNAL TALAR D E T O R S I O N 25* ( + 5 0 ° ~ 2 5 °
.
.
YEARS
| 5
ADULT
.
i
:
:
:
:
:
:
I
15
0
0
\
cZ]
Fig. 5 . - - M a l f o r m a t i v e correspondence between the hip and the " c o x a pedis": luxation (above) and protrusion (below) representing the extreme o f dysplasia of which the intermediate in sub-luxation and pre-luxation dysplasias by the hip that corrects an initial antiversion, in sub-protrusion and pre-protrusion (evolutive valgus foot in children) by the " c o x a pedis" that corrects an initial retroversion.
70
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994
THE COXA PEDIS
PISANI
ing of the "coxa pedis", restricted in its motion by the subtalar joint restraints, allows to modulate to the stable foot the directionality of the forces.S As already mentioned, one has to take into account the completion of the bearing phase of two enarthrosis that are in a contemporary "instantaneous functional arthrodesis."
Anatomic correspondence From an anatomic point of view, the morphological analogies of the neck and head of the talus with the proximal epiphysis of the femur are evident, in particular considering the talus blocked in the malleolar princes by the stabilizing action of the posterior muscles of the leg, a condition in which it becomes functionally "leg bone". If we imagine the carrying out of a frontal resection through the hip and a sagittal resection through the "coxa pedis" and if we consider the talus as bone of the leg, the os ilium-pubis profiles of the proximal acetabulum has analogic correspondence in the calcaneo-navicular profiles of the distal acetabulum and the interposed acetabular fossa of the first corresponds to the fibro-glenoid component of the second. The head and neck of the femur correspond to the talus head and neck, femoral diaphysis to the tibial diaphysis. And observing on the proximal section the greater and lesser trochanter, these have projective distal correspondence in the fibular and tibial malleoli. This anatomic correspondence is particularly significant in initial development phases. The anatomic documentation collected by Giannini and Bachechi on the new-born child (Fig. 3A, B) is of interest.
Evolutive correspondence From an evolutive point of view, considering the detorsion of the talar and the femoral neck (Fig. 4), they are opposite in direction, but overlapping by their relative angular values; this is to maintain the normal opening of the functional angle of declination of the talus as regards the gait direction. Starting from the approximate values from birth of 5 0 ° talar declination (retroversion) and a 40 ° femoral declination (anteversion), we reach the definitive aver-
Vol. l - No. 2-3
Fig. 6.--Unilateral luxation o f the " c o x a pedis" in a 6 year old child: the epiphysis, hixated above and externally, does not have any correlation of congruity with the "cotile pedis"; this appears reduced by hypertrophy and convexity of the posterior talar surface. The results, comparatively with the normal counter-lateral, reproposes the pathologic anato m y o f the luxated hip.
age value of 25 ° for the former towards 6-7 years of age and 15 ° for the latter towards 12-14 years. 6 9 It we imagine overturning the foot anteriorly on the hip the angular values of torsion, and their detorsional moments, also become overlapping in direction. As Volpi e t al. rightly confirm, to correlate the variations in which the retroversion angle of the talus and antiversion of the femur go towards, really means checking that which is the trend of the torsion on a transvers plane of the inferior limb during growth.
Malformative correspondence As regards the malformative pathology (Fig. 5), the dislocation and protrusion of the hip are known as the extreme dysplasias among those which are included the intermediate as that are the subluxation
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Fig. 7 A, B.-- The three components of the deformity (equine, supination, adduction) in the club-foot in new-born. The talar epiphysis is valued clinically sub-luxated dorsally and externally and is notable by surgical treatment its reduction with a cotyloideal lysis.
Fig. 8.--"Rocking shape" apsect of the foot in the congenital vertical talus. The talar epiphysis is valued, clinically, protruding down and medially and is notable, by surgical treatment, its reduction with a cotyloid cavity stabilization (4 year old child).
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Fig. 9 A, B.--The dysplastic characteristics of the "coxa pedis" in the club-foot (A: luxation) and in the congenital vertical talus (B: protrusion) are well definable radiographically.
and the preluxation; corresponding to the " c o x a pedis" we can define intermediate dysplasias (evolutive valgus foot in children) included between the two extremes represented by the expressed luxation o f the congenital club-foot and by the protrusion corresponding to the vertical talus. 3 to 11 In exceptional cases of a congenital dislocation o f the talus (Fig. 6) in which the head of the talus has no correlation of congruency with the cotyloid cavity, it appears radiographically deformes and stunk with h y p e r t r o p h y and posterior convexity of the navicular correspodingly to the anatomo-radiographic image o f the hip openly dislocated. On the contrary, in the talar protrusion, in which the more manifest result is represented by the congenital rigidus flat foot, the head and the neck o f the talus are sunken in the cotyloid cavity. In this case more enlarged while the navicular, dorsally hypertrofic, is almost in contact with the trochlea.
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PISANI
Fig. 10 A - D . - - X - r a y o f degenerative-structural pathology o f an arthrosic type of the "coxa pedis": similarly to the hip, next to the picture essentially definable (A, B), others are definable in the ambit of dysplastic pathology (C, D).
The clinical characteristics of the club-foot are ble also in the newly-born stage and which confirm konwn with the three components in equinus, supi- the characteristics of the cotyloid dysplasia are also nation and adduction (Fig. 7). Equally the clinical known (Fig. 9). characteristics of the congenital vertical talus are The pathological anatomy of the two deformities known (Fig. 8) with its unmistakable "rocking shape" is a confirmation of a common malformative pathoP aspects: it is of importance the fact, clinically, that o g y relatively to the concern of the regional dysplait is possible to value the head of the talus dorsally sia of the coxa pedis. and laterally dislocated in the clubfoot, while it is proRegarding the club-foot documentative is the truded down-ward and medially in the congenital ver- iconography showed by Perugia, Ricciardi Pollini and tical talus. Ippolito at the 61st Congress of the Italiam Society The roentgenographic appearance already defina- of Orthopedy and Traumatology (Milan, September
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30, 1976): in the p h o t o m i c r o g r a p h section o f a foetus's foot (Fig. 3C), a club-foot bearer, the sustentaculum tall is almost joined to the navicular while the head of the talus is arranged laterally to these two formations; the corresponding space is missing at the operating reports o f a sustentaculum-navicular joning with a reduction o f the cotyloid b o t t o m formed, in the residual part, by a thick fibrous magma. We have the contrary in the congenital vertical talus (Fig. 3D): the talus head, operatively, is o f immediate valuation by only just moving the posterior tibial tendon downward: protruding between the sustentaculum tali and the navicular it is only just contained by a thin fibrous b o t t o m without a glenoideal appearance. The anatomo-pathologic analogies between the dysplasia o f the hip and o f the " c o x a p e d i s " reproposed themselves in terms o f treatment: 10-12while in the club-foot the therapeutic p r o b l e m is to reduce the talar epiphysis in the "cotile pedis" exactly the same way as in the luxation coxa congenita, in the congenital vertical talus the problem is to extract the talar epiphysis from the cotyloid cavity from which m o r p h o l o g y and stability have to be re-established. The fact m a y seem not analogous that at the hip level the intermediate dysplasias are more often on a subluxation way, while at the " c o x a pedis" level the protrusion type are more frequent (talar protrusion in the ambit o f evolutive valgus foot in children). The none analogy is only apparent as the detorsions o f the talar and femoral neck are inverted: while the femoral neck, anti-verse, tends to centre itself starting from a subluxation disposition, the talar neck, retr0verse, tends to centre itself starting from a protrusion disposition. It is evident, however, h o w the least dysplasias, more often by an evolutive failure, are more frequently in luxation for the hip and in protrusion for the "cotile pedis". This malformative analogy, which we can define as a system, between hip and " c o x a p e d i s " has collations in not exceptional congenital luxation cases o f the hip associated to the club-foot. The cases o f d u b - f o o t on one hand and vertical talus on the other, are not even exceptional in the same system even if opposite by eccess and defect.
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In a degenerative pathology ambit (Fig. 10), there is a radiographic correspondence of arthrosic pictures of the " c o x a pedis" with the typical structural lesions concerning the hip at times essential, more often in the context of a degenerative pathology on a dysplasic basis. Riassunto L'articolazione talo-calcaneo-naviculare b analogicamente corrispondente sia da un punto di vista anatomico (differenziazione anartrosica) che evolutivo [torsioni scheletriche patologiche (lussazione, protrusione)] all'articolazione coxofemorale. A questi riferimenti il concetto e la definizione di ~
Coxa pedis.
References 1. Testut L, Jacob O. Trattato di anatomia topografica. Torino: Ed Ital UTET, 1946. 2. Volpe A, Marconi F, Pozza V, Spizzo L. La coxa pedis e le sue caratteristiche anatomiche: analogie e discordanze con la coxa femorale. Clair Piede 1986;X:401. 3. De Palma L, Coletti V, Santucci A, Tulli A. Aspetti embriogenetici della coxa pedis. Archivio Putti 1986;36:113. 4. Pisani G. The concept of the "coxa pedis". Rel XVI Congr. SICOT, Monaco di Baviera, 17 agosto 1987. 5. Pisani G. Biomeccanica clinica del piede. Collana Monografica ~Chirurgia del Piede)~. Torino: Ed Minerva Medica, 1983. 6. Pisani G. La t~coxa pedis~) e i mornenti torsionali astragalici. Chir Piede 1988;XI:35. 7. Pisani G. Function astragalienne et function calcan6enne du membre inf6rieur. Chir Piede 1985;XI:407. 8. Pisani G. Funzione integrata dell'arto inferiore. Giorn Scient di Primavera, Noto, 13-15 rnaggio 1988. 9. Milano L. I momenti torsionali astragalici. Minerva Ortop 1983;XXXIV,6:257. 10. Pisani G. La chirurgia legamentosa nella protrusione della t~coxa pedis)). Relaz Congr Soc Ital di Med e Chir del Piede, Bari, giugno 1982. 11. Pisani G, Milano L. La componente legamentosa nella patologia della ~coxa pedis~. Chit Organi Mov 1982-83;LXVIIl,iv-vi;717. 12. Pisani G, Milano L. Patologia evolutiva del cornplesso legamentoso periastragalico. Chit Piede 1983;VII,3:153.
EUROPEAN JOURNAL OF FOOT AND ANKLE SURGERY
August-December 1994