Instabilità delle protesi d’anca:
Patogenesi, clinica , diagnostica
A.Palermo
Clinica San Gaudenzio NOVARA
Casa di cura Villa Montallegro GENOVA
Clinica Villa Ragionieri FIRENZE
Il carico fisiologico sulla testa femorale è
determinato dalla risultante R delle forze che
agiscono sull’ estremità prossimale del femore in
appoggio monopodale. Il peso del corpo meno
quello dell’ arto sotto carico K agisce medialmente
all’ articolazione. K è bilanciato dalla forza M degli
abduttori. Il braccio di leva OC della forza K è >3
volte di quello OB della forza M
Biomeccanica dell’ anca normale e patologica:
fondamenti teorici, tecniche e risultati del
trattamento.
Friedrich Pauwels
“Placement
of the center of the acetabulum as far
medially, inferiorly, and anteriorly as is anatomically
possible is of prime importance in reducing the loads at
the hip.” Increased rates of loosening of both the
femoral and the acetabular component have been
associated with an initial position of the acetabular cup
outside of the true acetabular region.
Johnston, R. C.; Brand, R. A.; and Crowninshield, R. D.: Reconstruction of the hip.
A mathematical approach to determine optimum geometric relationships.
J. Bone and Joint Surg. July 1979; 61-A:639-652.
“a higher incidence of loosening of the femoral component when the centre of
rotation was placed 30 mm superior and lateral to the normal position”
Yoder SA, Brand RA, Pedersen DR, O'Gorman TW. Total hip acetabular
component position affects component loosening rates.
Clin Orthop 1988; 228:79-87.
“inferior displacement of 20 mm maximised the isometric abductor moment,
whereas superior displacement of 20 mm decreased it”
Delp SL, Maloney W. Effects of hip center location on the moment
-generating capacity of the muscles. J Biomech 1993; 26:485-99.
“placing the centre of rotation 15 mm superior to the normal position increased the rate
of revision of both the cup (p < 0.01) and the femoral component (p < 0.04)”
Pagnano MW, Hanssen AD, Lewallen DG, Shaughnessy WJ. The effect of
superior placement of the acetabular component on the rate of loosening after
total hip arthroplasty. J Bone Joint Surg [Am] 1996; 78-A:1004-14.
“placing the centre of rotation within 10 mm of the normal position, or even
more medially, was
associated with less loosening of the socket (p = 0.016). Superior or lateral
displacement greater than 10 mm increased the incidence of loosening of the
socket”
Stans AA, Pagnano MW, Shaughnessy WJ, Hanssen AD.
Results of total hip arthroplasty for Crowe type III
developmental dysplasia. Clin Orthop 1998; 348:149-57.
RISPETTO DEI TESSUTI
RISPETTO DEL PATRIMONIO OSSEO
RIPRISTINO DELLA BIOMECCANICA ARTICOLARE
APPROCCIO CHIRURGICO
RICOSTRUZIONE ANATOMICA
TSS
F.Pipino
DOPPIO ACCESSO
ANTEROLATERALE
ANTERIORE
POSTERIORE
LATERALE DIRETTA
POSTEROLATERALE
LA SCUOLA
Ricostruzione Anatomica
•Antiversione
•Lunghezza Arto
•Off-set
•Grandi teste (ROM,…)
11
INSTABILITA’-LUSSAZIONE
CAUSE
IMPINGEMENT
PROTESI-PROTESI
IMPINGEMENT
OSSO-OSSO
INSTABILITA’ PURA
Il design incide sul rischio di lussazione
•
•
•
•
•
•
Diametro della testa
Morfologia del collo protesico
Offset
Altezza dell’osteotomia del collo
Angolo cervico diafisario
Profondità del cotile e geometria del
bordo
IN VITRO ROM TEST
ROM GONIOMETRIC EVALUATION
HEAD from 28 to 44
W.J. MALONEY, CCJR, ORLANDO 2002
CNECK
FEMORAL
ANTEVERSION
0
°
15
°
STEM ON BONE
IMPINGEMENT !!!
30°
RE @ 0° FL
102
16
63
0
104
18
64
+3,5
106
18
64
+7
99
9
51
+10
99
9
53
FLEXION
RI @ 90° FL
RE @ 0° FL
-3,5
116
38
34
0
121
43
35
+3,5
124
45
38
+7
118
39
25
+10
117
39
24
NECK
BONE ON BONE
RI @ 90° FL
-3,5
NECK
HEAD 28mm
FLEXION
FLEXION
RI @ 90° FL
RE @ 0° FL
-3,5
111
31
43
0
115
34
45
+3,5
117
36
48
+7
112
26
35
+10
113
25
35
FEMORAL
ANTEVERSION
0
°
NECK
F LEXION
-8
103
19
-4
105
22
70
0
107
24
71
+4
110
26
73
+8
112
28
74
NECK
HEAD 38mm
15
°
STEM ON BONE
IMPINGEMENT !!!
30°
RI @ 90° FL
FL
RE @ 0°
69
RE @ 0° FL
-8
115
35
50
-4
119
41
48
0
124
47
47
+4
125
48
48
+8
127
51
49
FLEXION
RI @ 90° FL
RE @ 0° FL
NECK
BONE ON BONE
FLEXION
RI @ 90° FL
-8
110
29
57
-4
116
35
57
0
118
38
57
+4
120
41
56
+8
123
42
58
Restoring Normal Hip Motion
Implant Design Factors
Philip C Noble
The Institute of Orthopedic Research and
Education, and
Baylor College of Medicine, Houston, TX
Normal Hip Motion
120
Posterior dislocation
(flexion)
100
ROM (degrees)
80
60
40
20
0
Anterior dislocation
(external rotation)
Results –Flexion Activities
130
Range of Motion (degrees)
Intact
120
THR
HR
110
100
90
80
70
Flexion
Sit to Stand
Shoe Tying
Cross Legs
Core Study Group: Avg Intact Anteversion: 8.1°
Results –Extension Activities
Range of Motion (degrees)
60
Intact
THR
HR
50
40
30
20
10
0
Extension
Pivot
Roll
Core Study Group: Avg Intact Anteversion: 8.1°
Functional limits:
• extension to 30°
• pivot to 20° ER
• roll to 20° ER
Change in Flexion with Head Size
115
Flexion (deg)
110
28mm head
38mm head
105
100
95
90
p<0.0001
p<0.0001
85
Impingement
Dislocation
Effect of Neck Diameter on ROM
160
Neck
Diameter
ROM (deg)
150
12mm
140
11mm
10mm
9mm
130
120
110
28mm
36mm
Head Size (mm)
42mm
QUALE FUTURO PER I GRANDI DIAMETRI ?
Head Size and ROM at Dislocation
Increase in Flexion (Deg)
14
10° Adduction
20° Adduction
30° Adduction
12
10
8
6
4
2
0
22-26
22-28
22-32
Change in Head Size [mm]
28-32
Head Size vs. Mechanism of Dislocation
60
Frequency (%)
Impingement
Prosthetic
Bony
40
20
0
22mm
26mm
28mm
Femoral Head Size
32mm
Lo dira’ il Tempo
The Cross-Sectional
Morphology of the
Femoral Neck
Sup
Post
Cross-sections through the normal neck
Ant
Inf
Alternative Philosophies of Neck Design
Cylindrical
AP Flats
Asymmetric
Modeling Impingement
Cross section
through
neck
Sit to Stand
Roll
Impingement locations
Sit to stand
anterior
Stoop
Tie shoes
Leg Cross
Pure flexion
lateral
medial
Leg cross
posterior
Roll over
Stoop
GRANDE IMPORTANZA ALL’ORIENTAMENTO DEL COTILE
VERTICALITA’
CONCLUDENDO
CLASSIFICAZIONE INSTABILITA’ PTA
1°
MAL MOVIMENTO (senza anomalie radiografiche da malposizionamento)
2°
MALPOSIZIONAMENTO (cotile o stelo)
3°
NON BILANCIAMENTO TESSUTI MOLLI
4°
MALPOSIZIONAMENTO E NON BILANCIAMENTO TESSUTI MOLLI
TRATTAMENTO
1° SUCCESSO DOPO RIDUZIONE INCRUENTA
2° REINTERVENTO
3° REINTERVENTO dopo LUSSAZIONI RECIDIVANTI
4° PIU’ REVISIONI
LAWRENCE DORR
L’INSTABILITA’ PUO ESSERE TRATTATA CON SUCCESSO
ANCHE CON LA RIDUZIONE INCRUENTA COME PRIMA SCELTA
MA
IN CASI DI ACCERTATA INSTABILITA’ DEI TESSUTI MOLLI
O DI MALPOSIZIONAMENTO DELLE COMPONENTI E’
NECESSARIA LA STRATEGIA CHIRURGICA !!!
A.Palermo
G.Calafiore
M.Rossoni
R.Simonetta
A.Ascia
S.Cannizzaro
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