DARTHROPLASTY – Practical Training – Wet Labs - Part 2

WARSAW
11-12 November 2016
PART 2
www.darthroplasty.com

1
It is the oldest acetabular procedure
in human medicine.
First described by König in 1891.
Numerous descriptions and variations:
Albee, 1915 Schede, 1933
Spitzy, 1924 Heyman, 1963
Lance, 1925 Mizuno, 1975
Ghormley, 1931 Wainwright, 1976
HUMAN SURGERY
Acetabular Augmentation or Shelf Operation

2
Acetabular Augmentation or Shelf Operation

3
Butée de La Hanche or Shelf Operation

4

5

6
• The bone graft may be placed
beneath the capsule or over the capsule.
• May be secured by bone pegs or wedges,
screws, plates or soft tissue structures
(tendons, muscles).
• The human patient can be externally
immobilised in a splint for some weeks or not.
Staheli, L., et al (1992) Slotted Acetabular Augmentation in
Childhood and Adolescence. J Pediatric Orthopaedics 12: 569-580

7
To create a congruous extension of the
acetabulum overcoming the deficient
femoral head coverage.
Shelf = a projecting layer of bone
to support the femoral head.
The principle in all these techniques is:

8
Kotaro R. Shibata, et al. (2016) Open treatment of dysplasia
- other than PAO: does it have to be a PAO?
Journal of Hip Preservation Surgery Vol 0, Nr 0, pp 1-14
“The Shelf reinforces the fibrous capsule
of the joint preventing lateral and upward
subluxation of the femoral head.”

10
The restoration of a normal loading surface area
can stop or slow down the progressive cartilage
degradation as long as it is not already far advanced.
The technique is not conferring hyaline cartilage
coverage to the femoral head, but instead the joint
capsule is interposed between the 2 surfaces.
The shelf does not complicate a future THR.
It would tend to facilitate the proper coverage of the
prosthetic acetabulum.
Witvoet, J (2005) Techniques for hip shelf procedure.
EMC-Rhumatologie Orthopédie 2 (2005): 248-261
Biomechanical justification for the Shelf

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1. A graft placed too high resorbed owing
to lack of loading.
2. A graft placed too low produced impingement
on the femoral head.
3. Inadequate stabilisation of the graft allowed
redislocation of the hip.
4. An augmentation of a lateralized acetabulum
provided coverage without improving the limp.
The problems encountered with the shelf were:

12

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• When the indication was pain it decreased in 44%
and was eliminated in 32%.
• In 35 hips with instability 57% rated good
and 34% rated excellent post-op.
• In dysplasia category 54% rated good
and 29% excellent.
157 hips in children and adolescents ranging from 2 to 21
years of age and different causes and morphologies of hip
dysplasia;
The indications for surgery in this population were pain
(71%), progressive subluxation (33%) and acetabular
insufficiency (22%);
Follow up from 2 to 14 years.

15
Yu-Ping Su, et al (2008) Slotted Acetabular Augmentation in the
Treatment of Painful Residual Dysplastic Hips in Adolescents and
Young Adults. J Formos Med Assoc, vol 107, nr 9
A deformed head is not impeditive to the shelf.

Most of the current literature is focused on adults in which
the shelf is being used for late presentation cases. In children,
early diagnosis makes it possible to treat with harnesses or
osteotomies that confer hyaline cartilage coverage to the head.
16

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Grade 1- No signs of arthrosis.
Grade 2 - Bone cyst or sclerosis without joint
space narrowing.
Grade 3 - Less than 50% joint space narrowing.
Grade 4 - More than 50% joint space narrowing.
Grade 5 - Joint space disappeared.
First the OA (DJD) grading system they used:
Rosset, et al (1999) Évolution à long terme des butées pour dysplasie de
hanche chez l'adulte. Courbe de survie sur 68 cas et étude rétrospective de
44 cas avec un recul minimum de 26 ans. Acta Orthopaedica Belgica, vol 65 - 3

Of these 44 hips only 4 (9%)
were reoperated before 15
years of placement; so most
failures occurred between 15
and 26 years post-op.
The author’s final remarks:
Even in the presence of OA
the shelf has a privileged place
in the conservative treatment
of painful acetabular dysplasia
in the adult patient.
18
Rosset, et al (1999) Évolution à long terme des butées pour dysplasie de
hanche chez l'adulte. Courbe de survie sur 68 cas et étude rétrospective de
44 cas avec un recul minimum de 26 ans. Acta Orthopaedica Belgica, vol 65 - 3
They report on 44 hips - Age of patients 17 to 55 years;
Minimum follow up time 26 years.
16 dysplastic non-dislocated;
19 subluxated and 9 dislocated hips.

19
Migaud, et al (2004) Long-Term Survivorship of Hip Shelf Arthroplasty
and Chiari Osteotomy in Adults. Clin Orthop 418 : 81-86
56 shelves; Age of patients 17-56 years; 32% with severe hip dysplasia
All hips had signs of OA:
Grade 2 = 42% Grade 3 = 32% Grade 4 = 25%
Grade 2 joints had a survival rate of 83% at 18 years follow up.
Grades 3 and 4 had a survival rate of 27% at 18 years follow up.
At the latest followup,
25 shelf arthroplasties had been converted to a THR:
17 before 15 years (early failures)
and 8 after 15 years of followup (late failures).
These 25 THRs were done without acetabular bone grafting
The severity of preoperative arthrosis was the main factor that
impaired the survivorship of shelf arthroplasty.

20
Migaud, et al (2004) Long-Term Survivorship of Hip Shelf Arthroplasty
and Chiari Osteotomy in Adults. Clin Orthop 418 : 81-86

21
Lambotte, et al (2009) Dysplasies et chirurgie correctrice.
Revue du Rhumatisme 76 (2009) 334–340
A multicentric study to define the functional
results of conservative hip surgery in OA
secondary to hip dysplasia in older patients
(20-50 years old).
“Operations of conservative hip surgery for
dysplasia at 20-50 years of age are now rare
in our hospitals. This decrease is explained
by better early diagnosis in the newborn and
because in the older patient affected with
OA, THR (even before 50 years of age) is
easy to perform and the recovery is faster”.

22
Lambotte, et al (2009) Dysplasies et chirurgie correctrice.
Revue du Rhumatisme 76 (2009) 334–340
They found 87% of good results at 15 years follow up if 3
good prognosis factors were present:
OA grade 1 or 2; patient less than 40 years old and isolated
acetabular dysplasia.
With OA degree 3 and patient more than 40 years old the
good results at 15 years were 66% and 63%.

23
Bartonicek, J. et al (2012) Bosworth hip shelf arthroplasty in adult
dysplastic hips: ten to twenty three year results. Int Orth 36: 2425-2431

• Under 40 years of age.
• With OA grade inferior to 3.
• With isolated acetabular dysplasia
(no proximal femur problems).
Most authors agree that in adults
the best results are obtained in patients:
24

25
Teot, L., et al (1983) Acetabuloplasty using pedicle iliac crest
epiphysis transplantation in puppies. Int Orthop 7, 1-9
In dogs aged 2-3 months they performed resection of the
lateral part of the acetabulum and covered the head with
a bone graft harvested from the iliac crest.

26
The graft was either pedicled or not (for control).
Fusion was reached in the majority of the dogs. In the pedicle
group the hyaline cartilage of the graft (epiphyseal) matured into
articular cartilage and in the union zone there was fibrocartilage.

27
But 2 years after surgery it had transformed to fibrocartilage
(reported in other study). In the non-pediculated grafts the
area in contact with the head matured to fibrocartilage.

28
• Samples of decalcified bone were implanted in soft
tissues mainly in Rabbits: pouches created in the rectus
abdominis, quadriceps or in the erector spinae muscles.
• These samples were invaded by several cell lineages
that started a process of substitution of that matrix with
host new-bone.
• “... decalcified bone yields new bone in an amount
proportional to the volume of the implant ...”
• Latter Urist discovered and proposed the name BMP
to a group of glycoproteins obtained from demineralized
cortical bone (Bone Morphogenetic Proteins).
Urist MR (1965) Bone: formation by autoinduction.
Science 150: 893-899

29
• Osteoinduction.
This term means that primitive, undifferentiated
and pluripotent cells are somehow stimulated to
develop into the bone-forming cell lineage.
• Osteoconduction.
This term means that bone grows on a surface.
An osteoconductive surface is one that permits
bone growth on its surface or down into pores,
channels or pipes.
• Osteogenesis.
Refers to bone formation (with no indication of
celular origin). A bone graft is said to be
osteogenic when it directly provides cells
that will produce bone.

30
Bone grafts can have 1 or more of these 3 properties:
osteoconductive (act as a structural framework).
It can be osteoinductive (providing BMPs, etc).
osteogenic (provides osteoblasts, stem cells, etc).
• Cell survival seems to be improved by minimizing
interval between harvest and implantation.
• Cancellous bone has more surface area (porosity)
than cortical bone and it is revascularized faster.

32
• Low osteotomy: 1-2 mm from the joint
• Medium osteotomy: 2-4 mm from the joint
• High osteotomy: 5-9 mm from the joint
The aim of the study was to examine the factors
that contribute to an effective and durable
reconstruction of the roof of the acetabulum
following Chiari's pelvic osteotomy in young
growing dysplastic dogs (5 to 12 months old).
The dogs were divided in 3 groups
(DV level of osteotomy):
Bohler, N; Chiari, K, et al. (1985) Guidelines for Chiari's osteotomy
in the Immature Skeleton Developed from a canine model.
Clin Orthop Rel Research, nr 192, 299-311

33
The cranial segment was lateralised and secured with a pin for 14 days.

34
The dogs were sacrificed at various periods for study.
They found various degrees of degeneration and arthrosis corresponding
well with the degrees of dysplasia determined radiographically.
The osteotomy gap was still clearly visible at 2 to 6 months post-op and
contained fibrous connective tissue and fibrocartilage over much of it's
length.

35
In the case of low and medium osteotomies, in which the femoral head
pressed against the newly formed acetabular roof, the distal end of the
fissure was open while at the proximal end it was bridged by osseous
tissue.
- 10 to 12 months post-op the osteotomy fissure was largely bridged by
osseus tissue.

36
Only in the low and medium osteotomy groups
did the newly formed roof of the acetabulum
extend the original acetabular rim.
The newly formed lateral rim extended laterally
by endochondral growth processes and was
covered by fibrocartilage.
In the high osteotomy group there was an
almost continuous resorption of the new
acetabular roof.

Similar experiment in 2 month old dogs
37
Bitan, F., et al (1989) Effets sur le développement cotyloidien
de l’ostéotomie de Chiari chez le sujet en croissance - Étude
expérimentale chez le chiot. Int Orth 13 : 167-172
“new roof” loaded “new roof” not loaded
(non-dysplastic dog)

38
BOP = Biocompatible Osteoconductive Polymer
BOP-F – the fiber form ; BOP-B – the block form
According to the authors: “BOP-B and BOP-F are partially degradable
by hydrolysis, allowing for ingrowth of bony tissue or osteoconduction.”
Jensen, DJ; Sertl, GO (1992) Sertl Shelf Arthroplasty (BOP
procedure) in the treatment of canine hip dysplasia. Vet Clinics
North America, Small Animal Practice. vol 22, nr 3, may 1992

39
Oakes, M.G. (1996) Evaluation of shelf arthroplasty as a treatment
for hip dysplasia in dogs. JAVMA, vol 208, nr 11, 1838-1845
They executed Sertl BOP surgery in the right hip and sham
surgery on the left (sham=doing the slot and loosely replacing
the bone recovered in the defect).
Necropsy findings at 6 and 12 months were similar:
The slot had healed
in the sham surgery group
and was closed and not
perceptible.
The slot persisted
in the BOP surgery group -
the implants were
unchanged in appearance
and surrounded by a thin
fibrous capsule.

40
Oakes, M.G. (1996) Evaluation of shelf arthroplasty as a treatment
for hip dysplasia in dogs. JAVMA, vol 208, nr 11, 1838-1845
“A large periacetabular bony shelf did not form in any of these
dogs, and the polymer fibers did not support osteoconduction
from the periacetabular slot during a 52 week (1 year) follow-
up period.”
“A small amount of periacetabular
bone (...) could be seen in 7 dogs.
Radiographically, the source of this
bone appeared to be the cancellous
bone that had been placed in this
area during the procedure (...) the
bone was located adjacent to the
acetabular margin, VENTRAL to
the polymer fibers (...)”.

41
“DARthroplasty provides dorsal support for the femoral
head and prevents the pain associated with joint capsule
tears from the dorsal acetabular rim (…) As the bone
graft forms an extracapsular DAR, the capsule becomes
a weight-bearing surface for the hip.”
Slocum B, Slocum T.D. DARthroplasty.
In: Bojrab, M.J., ed. Current Techniques in Small Animal Surgery,
4th Ed. Baltimore: Williams & Wilkins 1998: 1168-1170

42
Slocum´s results description is very poor and
no objective study was made (he died in 2001).
He reports:
• Experience with more than 300 hips;
• At 2 months post-op function is pain free;
• 4 months post-op dogs are fully functional and
playing and jumping without pain; after activity
they have no morning soreness;
• Limited abduction is typical;
• Range of hip extension increases;
• At 4 months the bone graft has fused.

43
Complications reported by Slocum:
• 1 patient with temporary sciatic dysfunction
that returned to normal after 6 months.
• Several patients with luxated head
displacement twice the femoral head
diameter had the sciatic nerve trapped
between the bone graft and the
sacrotuberous ligament.

44
• The shelf must be loaded – it’s dorsoventral level
is very important.
• The shelf must be robust – thickness of the shelf
and therefore bone quantity is very important.
• The shelf must correct the deficient coverage.
• The shelf should not confer excessive coverage
– interferes with abduction; the shelf can impinge on
the greater trochanter and/or neck.
• Blood supply to the shelf must be generous.
• The 1st layer should be pliable bone to better
conform to head shape; spongiosa is maybe the
best option (incorporated faster also).
Final remarks

WARSAW
11-12 November 2016
END OF PART 2
www.darthroplasty.com

DARTHROPLASTY – Practical Training – Wet Labs - Part 2

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