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Disasters of
Design
and Innovation
in THA
Timour El-Husseini
“Disasters of Design and Innovation in THA”, Instructional Course Lecture, 18 th Arthroclub Event El Salam Heliopolis Cairo Thursday 9 th 2006 © Timour El-Husseini

“Change is one thing, progress is another”
Bertrand Russell (1872–1970)
“Fashion is something barbarous, for it
produces innovation without reason and
imitation without benefit”
George Santayana (1863–1952)

Some THA Disasters
‣ Boneloc cement
‣ Isoelastic hip
‣ Exeter Matt stem
‣ Sulzer shell
‣ Hylamer cups
‣ Centralign stem
‣ Capital hip
‣ More……

Boneloc Cement
‣ In the mid 1980s Scandinavian Nurses
Association protested on possible teratogenic
effects of cement fumes during Arthroplasty ops
‣ A Danish Orthopaedic Surgeon responded by
inventing a cement that addressed this issue
and also addressed other sound ideas
‣ The Boneloc ® was quickly manufactures by a
Danish company, later distributed by Biomet

Boneloc Rationale
‣ Improve the mechanical and chemical properties of
conventional PMMA
‣ Decrease bone necrosis as well as more subtle chemical
and thermal damage to bone during implantation
‣ Reduce the exothermic temperatures generated during
polymerization
‣ Lower residual monomer content by ↓ solubility and
by ↑ molecular weight
‣ Enclosed mixing system preventing polymerization fume
release into theatre atmosphere

Boneloc Rationale
Revolutionary enclosed mixing system prevented fumes and allowed vacuum mix

Centigrade
Boneloc
80
76
70
60
62
50
40
30
Other
Boneloc
20
10
0
Ex Temp
• Maximum Acetabular in-vivo temp was 43 degrees
Wykman AG, Sandersjoo GA.
Low polymerization temperature with Boneloc. In vivo measurements in 11 hip replacements.
Acta Orthop Scand 1995; 66(3):218-219.

Boneloc
Unfortunately, although all the goals
seemed to be attained, the clinical
success of the product was poor !

Proportional Relative Risk
Boneloc
25
20
15
10
Other
Boneloc
5
0
Early Failure Risk
RR for Early Stem Loosening = 2.5 times conventional cement
Markel DC, Hoard DB, Porretta CA.
Cemented total hip arthroplasty with Boneloc bone cement.
J South Orthop Assoc 2001; 10(4):202-208.

Boneloc
‣ Denmark, Riegels-Nielsen et al
Loosening in 24 of 43 hips at an average 18-month FU
‣ Finland, Suominen
Loosening in 4 of 8 stems in hybrid reconstructions after FU of 32
month
‣ Norway, Nilsen and Wiig
Loosening in 102 of 157 hips at an average FU of 2 years
Riegels-Nielsen P, Sorensen L, Andersen HM, et al:
Boneloc cemented total hip prosthesis. loosening in 28/43 cases after 3-38 months.
Acta Orthop Scand 66:215, 1995
Suominen S:
Early failure with Boneloc bone cement. 4/8 femoral stems loose within 3 years.
Acta Orthop Scand 66:13, 1995
Nilsen AR, Wiig M:
Total hip arthroplasty with Boneloc: loosening in 102/157 cases after 0.5-3 years.
Acta Orthop Scand 67:57, 1996

Boneloc
‣ Failure in these cases was due to poor
mechanical properties such as a reduced tensile
strength and elastic modulus when compared
with a standard cement
‣ In addition, an increased amount of monomer
appeared to be released from the cement,
contrary to one of the original objectives
Thanner J, Freij-Larsson C, Karrholm J, et al:
Evaluation of Boneloc. chemical and mechanical properties, and a randomized clinical study of 30 total hip arthroplasties.
Acta Orthop Scand 66:207, 1995

Boneloc
‣ Boneloc was used in 4,500 patients,
mainly in Scandenavia
‣ After a long legal battle Boneloc was
withdrawn in 1995
‣ The Danish Originator was jailed briefly
‣ Biomet did not offer compensation
package

RM Isoelastic Hip
Idea
Elastic Stem will produce less stress concentration = slower resorption/osteolysis
Morscher and Bombelli, 1980

Isoelastic Hip
‣ 28 patients have been observed for a period of more
than 1 year after surgery.
‣ We did not find loosening or incompatibility of the
polyacetal-resin material.
‣ We believe the implantation of this prosthesis type
without cement fixation is especially advantageous.
‣ The histologic result of a patient who died 6 weeks after
surgery did not reveal any tissue incompatibility.
‣ We observed an excellent fixation of the prosthesis by
bone growth into the surface indentations of the stem
Morscher E, Bombelli R, Schenk R, Mathys R.
The treatment of femoral neck fractures with an isoelastic endoprosthesis implanted without bone cement.
Arch Orthop Trauma Surg 1981; 98(2):93-100.

Isolelastic Hip
‣ The results in 627 cementless polyethylene cups after a
maximum observation period of 5.5 years reveal good
incorporation and no aseptic loosening
‣ Especially favorable results occurred in 61 cases by
replacing loosened cemented cups with bone grafts and
cementless polyethylene cups
‣ On the femoral shaft side too high an elasticity in the
proximal part of the prosthesis led to bone resorption
and loosening with the first model of the prosthesis
‣ By reinforcing the proximal part of the femoral
component, much better results were obtained.
‣ The isoelastic femoral shaft, however, is in an early
stage of experimentation
Morscher EW, Dick W.
Cementless fixation of "isoelastic" hip endoprostheses manufactured from plastic materials.
Clin Orthop Relat Res 1983;(176):77-87.

Isolelastic Hip
‣ After average 9.1 years 19.3% of the cups and 30.8% of
the stems shows radiolucent lines over 2 mm
‣ We conclude that the isoelastic RM stem shows a high
rate of loosening, but that this is not always associated
with a poor subjective result. Regular radiographic
review is necessary. The results are worse than those
reported for other uncemented stems and for cemented
stems
Grunther RA, Oest O, Sussenbach F.
[The isoelastic RM hip endoprosthesis].
Z Orthop Ihre Grenzgeb 1993; 131(6):539-542.
Niinimaki T, Puranen J, Jalovaara P.
Total hip arthroplasty using isoelastic femoral stems. A seven- to nine-year follow-up in 108 patients.
J Bone Joint Surg Br 1994; 76(3):413-418.

Isolelastic Hip
‣ A high incidence (41%) of lateral migration of the tip of
the femoral components was noted, but there was no
significant distal migration.
‣ Nine patients complained of thigh pain, which interfered
with their daily activities.
‣ The average Harris hip score improved from 49 to 80 at
the latest follow-up.
‣ We believe that the principle of isoelasticity in hip
replacement is important; however, improvements in the
material and the design of the femoral component are
required
Ali MS, Kumar A.
Isoelastic femoral component in primary cementless total hip arthroplasty.
Int Orthop 2002; 26(4):243-246.

Isolelastic Hip
‣ RESULTS: To date, 69 hips (64 patients) have been revised, 5 due to
infection. The 10-year survival rate for any reason was 70% (66-74). In the 46
remaining patients (53 hips), the average HHS was 80 (39-100) points. 13 of
these were regarded as radiographic failures, with an average HHS of 75
points
‣ INTERPRETATION: The performance of this prosthesis was unacceptably
poor. Higher debris production and poor primary fixation are believed to be
the main reason for the high failure rate
Trebse R, Milosev I, Kovac S, Mikek M, Pisot V.
Poor results from the isoelastic total hip replacement: 14-17-year follow-up of 149 cementless prostheses.
Acta Orthop 2005; 76(2):169-176.

Contemporary Cemented and Cementless Stem Survival Rate

“This is the Serendipity Hip”
Ling R., The second Exeter Hip Expert Congress
Istanbul, 1997

Exeter Polished Stem
‣ The original Exeter femoral components were
manufactured with EN58J with polished surface.
‣ There was no particular reason for this at the time,
except that it was 'the fashion' for many femoral
components of that era, the early Charnley 'flatbacks'
being an example.
‣ No particular significance was attached to the type of
surface finish in 1969.

Exeter Matt Stem

Exeter Matt Stem
‣ To avoid stem fracture, L316 was used in 1976.
‣ Matt finish was chosen for the new stem.
‣ There was no particular reason for this at the time,
except that 'the fashion' for femoral components turned
to the matt or rough finish
‣ No particular significance was attached to the type of
surface finish at the time of change (1974-1976)
‣ But such small change proved to be of crucial
importance

Exeter Matt Stem

Surface Finish
5 LEVELS
According to Surface Roughness Average:
1. Highly polished
2. Satin
3. Matt
4. Rough
5. Textured

Surface Finish
Ra= 0.05 um Ra= 0.64 um Ra= 0.8 um
Ra= 1.22 um Ra= 2.40 um Ra= 14.20 um

Exeter Matt Stem
We reviewed at a minimum elapsed time of five years a
consecutive series of 143 primary Exeter hip
replacements in which matt-surfaced femoral stems had
been used. Twenty-five patients had died and six stems
and two sockets had been revised before follow-up. The
remaining 110 hips were all examined clinically and
radiographically. In 15 hips there were radiographic
signs of definite loosening of the stem and in eight
suspected loosening. The acetabulum was loose in four
hips. In another eight hips localised bone resorption was
present without signs of loosening. Half the patients with
loosening or localised bone resorption had mild pain or
no pain at all. The late complication rate with the mattsurfaced
Exeter femoral stem is unacceptably high.
Rockborn P, Olsson SS.
Loosening and bone resorption in exeter hip arthroplasties. Review at a minimum of five years.
J Bone Joint Surg Br 1993; 75(6):865-868.

Exeter Matt Stem
‣ Prospective comparison of the incidence of loosening of 20 femoral
stems with a matt surface with that of 20 polished stems of an
otherwise identical tapered, non-modular design of Exeter hip
replacement
‣ All the patients were reviewed regularly and none was lost to followup
‣ After a minimum follow-up of nine years, four matt but no polished
stems had been revised for aseptic loosening.
‣ Polished stems subsided slightly within the cement mantle early, but
did not loosen
In the presence of the polished design Exeter stem, the use of the
matt design should be abandoned
Howie DW, Middleton RG, Costi K.
Loosening of matt and polished cemented femoral stems.
J Bone Joint Surg Br 1998; 80(4):573-576.

Sulzer Inter-Op
Acetabular Shell

Sulzer Inter-Op
‣ A nightmare started Dec. 8, 2000 when Sulzer
USA told Orthopaedic Surgeons a mistake in the
manufacturing process had affected 31,000 hip
implants -- in a part called the Inter-Op
acetabular shell
‣ Suspected batches produced since October
1999 and possibly as far back as 1997
‣ All Sulzer Acetabular Shells were subjected to
FDA recall, BUT
‣ An estimated 17,500 of the defective shells were
implanted in patients.

Problems attributed to Oil-on-Shell
‣ Loss of 1ry stability = Immediate shell
fixation failure
‣ Loss of 2ry stability = early shell fixation
failure

Sulzer Inter-Op
Lubricant contamination by:
‣ Mobil DTE 24
‣ Mobil Velocite Oil No. 8
‣ Mobil Velocite Oil No. 6
‣ Mobil Vactra Oil No. 2 and
‣ Mobil Vactra Oil Heavy.
LUBRICANT
CUTTING
HEAD
COOLANT

Mac Reynolds revised 120 out of 245 cups over the 1 st year

Sulzer Inter-Op
Sulzer USA offered compensation package for revision surgery

Disasters of Design
‣ It is difficult to decide when a new product
should be introduced,
‣ especially when the new product is designed to
replace or improve on an existing product that
has a long history of clinical success.
‣ This notion is further convoluted by the fact that
surgical products are commonly introduced with
financial incentives by industry.

Disasters of Design
‣ When a new product or procedure is
introduced to the medical community, it is
imperative to compare its performance
with the established standards of care
‣ The responsibility of the surgeon to verify
that could not be ignored, inorder not to
add insult to injury

Thank You
‣ For
‣ Your
‣ Attention
“Change is one thing,
progress is another”
Bertrand Russell (1872–1970)