the results of cementless cups (hap or ti) with additional divergent pegs and acetabular...
TRANSCRIPT
The results of cementless cups (HAP or Ti) The results of cementless cups (HAP or Ti) with additional divergent pegs with additional divergent pegs
and acetabular reconstruction with graft and acetabular reconstruction with graft in failed THAin failed THA
The concept of “migration en bloc”The concept of “migration en bloc”
(1993)(1993)
JL. Lerat, C. FalaiseJL. Lerat, C. Falaise
LYON - France LYON - France
EFORT Congress (June 2001- Rhodes)EFORT Congress (June 2001- Rhodes)
Special Cup with pegs for revision Special Cup with pegs for revision 1st model : «Spring» «Spring» ( Landanger-Depuy 1993 - 2000 )( Landanger-Depuy 1993 - 2000 ) Special Cup with pegs for revision Special Cup with pegs for revision
1st model : «Spring» «Spring» ( Landanger-Depuy 1993 - 2000 )( Landanger-Depuy 1993 - 2000 )
• Metallic cup ( Ti ). Hydroxyapatite coating
• 6 holes for 6 pegs fixed with the cup by threading
• Alumine on polyethylene
1rst model (alumine on polyethylene) : 128 cases
6 divergent pegs bring usually a good primary stability
: 10 and 15 mm (in the majority of the cases)
or 20, 25, 30 mm
The most frequent cause of revision is cemented cups with bone defects
corresponding to the amount of cement: 91 cases
Revision of non-cemented cups : 29 cases
Revision of cemented acetabular rings previously used for revision : 4 cases
128 acetabular revisions (11 infected)
• 75 complete revisions
• Previous operations : 1 to 8• Previous surgery : 9.8 ± 5 years
• Females : 88• Mean age : 64.4 ± 11 Ys• Mean follow-up : 4.6 y ± 1.7 (1 to 7 y)
• One surgeon, one technique
Material
Acetabular reconstructionAcetabular reconstruction
Simple prolongation of the posterior incisionSimple prolongation of the posterior incision
• Iliac crest autograft : 85• Bone from reaming : 33 • Opposite femoral head : 1
} } 93 %93 %
Acetabular reconstruction Acetabular reconstruction
• Iliac crest autograft : 85• Bone from reaming : 33 • Opposite femoral head : 1
• + Allograft :
1 femoral head : 43
2 femoral heads : 4
3 femoral heads : 2
• + bone substitute : 6
Iliac crest is grafted : 38 cases
} } 93 %93 %
}} 38 %38 %
Prolongation of the posterior approach toward the posterior iliac crest
Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle
Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle
Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle
Paprosky : Type I (n = 31)Paprosky : Type I (n = 31)
Easy cases : graft into the holes, sufficient contact of the
cup with the host bone
Paprosky : Type II (n = 63)Paprosky : Type II (n = 63)
• The cup may be stabilised between the 2 columns
• Press-fitting the acetabular component is often possible
• 1 iliac crest is sufficient
A (n = 20) B (n = 22) C (n = 21)
- Autograft into the holes and for the roof reconstruction- Bone is impacted with the « trial cup »- Stabilisation by press-fitting the cup between the 2 columns + 6 pegs
Paprosky : Type II (n = 63)Paprosky : Type II (n = 63)
Massive bone graft is necessary for the reconstruction of :
- the centre
- the columns
- the roof
Paprosky :Paprosky : Type III (n = 32)Type III (n = 32)
III A III A (n = 22) (n = 22) III B III B (n = 10)(n = 10)
The reconstruction of a column is made after the cup has been fixed to the host bone and to the graft
1 - Fixation of the component with pegs2 - Spongious autograft is placed on the HAP coating3 - The bone block is then fitted on the cup by 1 or 2 pegs
(or 1 adjusting srew) inside outside
Adjusting screws may be used to fit the graft against the cup
Or for the primary stabilisation of the cup
It is recommended to replace the screws by pegs for definitive fixation
The use of screws is not recommended usualy
Stability of the implantsStability of the implants
• Press-fit alone : 45
• Stability attained by the use of pegs : 83
The divergent pegs bring a complementary stability to cup
6 years
The stabilisation of the cup is obtained with graft incorporation
and remodelling under load-bearing conditions
Stability of the implantsStability of the implants
Immediate (partial) : 25
4 to 6 weeks : 48
2 to 3 months : 55
Weight load-bearingWeight load-bearing
ComplicationsComplications
• Dislocations (2 first months) : 9• Trochanteric non-unions : 6
(4 had previous non-unions)• Ossifications : 1• Infections : 3 (recurrence for 3 of 11 previous infections)
Cup + stem 75 casesCup + stem 75 cases• Blood loss : 1075 ml ± 883 (100-4500)
• Drainage : 650 ml ± 365 (20-1900)
• Op time : 192 min ± 60 (90-345)
Cup alone 53 casesCup alone 53 cases• Blood loss : 645 ml ± 534 (200-3400)• Drainage : 555 ml ± 293 (20-1170)
• Op time : 160 min ± 38 (90-300)
OperationOperation
Diameter of the cups
0
5
10
15
20
25
30
38 42 46 50 54 58 62
cupule enlevée
cupule "Spring"
Diameter of the cupsDiameter of the cups
CasesCases
Removed cups :Removed cups :
49.6 mm49.6 mm + cement+ cement
New cups :New cups :
55.9 mm55.9 mm
The mean diameter of the new cups increases, but the cement is replaced by bone graft
Cement Bone graft
Removed cups :Removed cups :
49.6 mm49.6 mm + cement+ cement
New cups :New cups :
55.9 mm55.9 mm
EvaluationEvaluation
Radiographic measurements• Incorporation /radio lucent line
• Stability in the 3 planes
- Numerised X-rays
- Precise measurements
(special software : “MetrOs” C. Falaise)
Functional value• PMA Score (Postel - Merle d'Aubigné)
• Lost for follow-up : 3
• Deceased : 8
• Revisions : 11• Loosening : 9• Infection : 2
• Patients reviewed : 102
Results
• Excellent : 69 • Good : 29 • Fair: 10 • Poor : 1
• Impossible to estimate : 27
Postel-Merle d’Aubigné score (18 pts)Postel-Merle d’Aubigné score (18 pts)
16.4 ± 2 / 1816.4 ± 2 / 18
The results are also influenced by the status of the femur
Type I Type 2 A Type 2 B Type 2 C Type 3 A Type 3 B
Excellent 16 15 11 10 4 0Good 7 3 7 8 3 0Fair 4 0 2 1 1 1Poor 1 0 0 0 0 0
The results are good for the 3 types of Paprosky
Results
• Complete healing : 94
• Pain at the iliac crest : 3
• Poor active abduction : 22
Results
Radio lucencies
• None : 87.7 %
• Zone I : 3.3
• Zone II : 1.6
• Zone III : 3.3
• Zone I,II : 0.8
• Zone II,III : 1.6
• Zone I,II,III : 1.6
Radiological results manual measurements
(Failed cases included)
• 86 % of the implants are stable at visual examination no migration, no radio-lucent line
• Vertical migration
2 to 6 mm : 3
> 6 mm : 5• Medial migration
2 to 4 mm : 2
> 4 mm : 7 • Verticalisation : 5.5 %
Important displacement : 7 cases
Revised by the same cup : 5
Computerised measurements
• Scanner Vidar• Definition : 150 Dot per inch• Selection 1 Pixel : 0.17 mm• Special software «MètrOs» (C. FALAISE)
• Navigation into the image with magnification
• Adjustment of the luminosity and contrast
• Scale adapted to the size of the implants
• Geometric constructions and calculation of index automatically
• « EBRA » method (Krismer - Innsbruck)– 6 index (3 longitudinal, 3 transversal)– 11 measurements– Accuracy : 0.7 mm
Computerised measurements Scale adapted to the size of the implants
Computerised measurements1) Ascension (1st measurement)
Computerised measurements Ascension (2d measurement)
Computerised measurements 2) Lateralisation 1
Computerised measurements Lateralisation 2
Computerised measurements 3) Inclination
Computerised measurements 4) Version
sin() = Rp/Rc= sin-1(Rp/Rc)
« EBRA » method
• Krismer et coll. 1995 (Innsbruck) • Control of mistakes due to incidence variations• Comparability of 2 films by measuring the position of constant
anatomical landmarks • Difference in size = Comparability Index
• For an index limited to 3 mm, the precision is ± 0.7 mm for the
experimental model and ± 1 mm in clinical study
Comparability of 2 films by measuring the position of constant anatomical landmarks
Longitudinal L1 - 2
6 index (3 longitudinal, 3 transversal)
Longitudinal L2 - 3
Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Transversal M1 - 2
Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Transversal M 2 - 3
Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Post-op
Inclination : 49° ± 7,5
Anteversion : 17.1° ± 9.9
Follow-up : 4 years
Inclination : 48.7° ± 9.8
Anteversion : 19.5° ± 12.4
Inclination and anteversion of the cups
Computerised measurements
Computerised measurements
Vertical plane
M - 1SD M + 1SD M + 2SD
Male 12 16.5 ± 4 21 25.5lowering Normal Ascension +
Female 11 16.1 ± 4 21 25
Horizontal plane
M - 1SD M + 1SD
Male 26 31 ± 5 36
Medial Normal Lateral
Female 21 25 ± 4 30
Position of the cup / U
Position of the cup / U ligne
Hip centre correct : 43 %
Migrations
Migrations = 45 % with computerised measurements
= 14 % visual method (migrations > 3mm)
Literature : maxi 9 %
Callaghan 9 % 4 years (JBJS 1985)
Kavanagh 9 % 4.5 years (JBJS 1985)
EBRA is the best method to detect migrations
(except RSA : roentgen stereophotogrammetry)
Ilchmann T. J. Arthroplasty 1992
Post op 6 months Stable after 1 year
1 example of verticalisation and ascencion
Stable Migration Total
type 1 15.1 9.2 24.4
type 2A 9.2 5.9 15.1
type 2B 10.9 5.0 16.0
type 2C 9.2 7.6 16.8
type 3A 7.6 10.9 18.5
type 3B 3.4 5.0 8.4
Consequences of migation when using screws = wear or screw fracture
The stability of a cup is achieved by bone remodeling.
We consider that a small migration is a normal phenomena
(proved by computerised measurements)
Postop 1 year
Mobility between the cup and the screws has consequences :
Impression in the polyethylene
± metallic wear
± fractures of the screws
The concept of “migration en bloc”The concept of “migration en bloc”
The pegs tend to limit the migration of the cup but should this occur, The pegs tend to limit the migration of the cup but should this occur, they migrate together in the same directionthey migrate together in the same direction
Failed revision Successfull revision Only 3 pegs with 6 pegs
+ 5 years
5 cups placed with screws failed and they had been
revised with a similar cup with pegs
5 ans
5 years
5 years
6 years
13 infected cases
Two-steps revision
3 recurences of infection finally healed
The limits of this cup
Type 4
Destruction of the roof and 2 columns
+ destruction of inferior bone
Failure of a 1rst revision using a cemented ring (Kerboul) Protrusio (6 years later)
What can we do for large defects « type 4 » ?
Granuloma + cement
The host bone and the cancellous bone graft cannot find any possibility of ingrowht on
this surface
Wagner’s acetabular ring for revision and massive bone graft
Cementless and metal on metal
Ti-6Al-7Nb Protasul TM
A part of a femoral head is placed in the defect
Cortico-spongious blocks to reconstruct the columns and the roof
Spongious morsellised bone (auto and allo graft) cover the precedent graft
The Wagner ’s ring is impacted and fixed with screws
Acetabular reconstruction with 3 femoral
heads + 80 cc of morsellised bone graft
The new Wagner’s ring (for type 4)
2 advantages : cementless ( Ti coating for bony integration )
and metal on metal
1 drawback : Migration is bound to happen ( problem with the screws)
pegs for future ??
Some examples of « Spring » cup
Failure of other kinds of revision rings
Failure of other kinds of revision rings
4 years
4 previous operations
Op. 2Op. 2 Op. 3Op. 3 Op. 4 Op. 4
Op. 5Op. 51 iliac crest +1 iliac crest +
1 femoral head1 femoral head
Face + 5 ans
7 years
Op. 5Op. 5 1 iliac crest + 1 femoral head1 iliac crest + 1 femoral head
The polyethylene debris are responsible for the loosening of the THA
Foreign bodies Granulomas
Acetabular reconstruction is often associated with femoral problems
Polyethylene and metal-back must be eradicated
Alumine - polyéthylèneAlumine - alumine
Zircone - zircone
Alumina on alumina
Metal on metal
Polyethylene must be replaced by better materials
Cup with pegs 2d generation (Cedior-Sulzer)
- Ti-6Al-7Nb Protasul
- 7 pegs- Metal / metal (metasul)
54 cases (since 6/2000)
Follow-up < 1 year
11 months
• Incorporation-stability of the cup :
success rate : 96 % in types 1,2,3(follow-up : 1 to 7 years)
• Restoration of bony structures :
autograft ++ or auto + allograft
ConclusionsConclusions
10 m
• Usefulness of non cemented cups (HAP or Ti)
• Interest of the pegs fixed to the cup
• Pegs are preferable to screws
• Pegs do not interfere with small migration during
osteo-integration
ConclusionsConclusionsConclusionsConclusions