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MEETING
OF THE HIP SOCIETY Thirtieth
Open Scientific Meeting The
Eighth Combined Open Meeting Hip Society and AAHKS Dallas,
Texas February
16, 2002 PROGRAM CHAIRMEN Joseph McCarthy, M.D. Richard White, M.D. CONTENTS: COURSE DESCRIPTION: This course is divided into seven sections. The first three sections deal with several aspects of DJD. The fourth section presents the three Hip Society award papers. Symposium five discusses head size, bearing surface and wear. The sixth section communicates late sequelae of hip joint trauma. In the final symposium the speakers will reveal some new views in THR. COURSE OBJECTIVE: The Objective of this Open Meeting of the Hip Society will be to convey information on important management decisions regarding hip surgery in the older, middle aged and the younger patient with osteoarthritis. In addition the Basic Science issues and controversies regarding head size, the bearing surface and wear will be addressed. There will be a symposium on the late joint effects on hip trauma. Finally, there will be a look ahead at upcoming techniques and technology in total hip reconstruction. INTENDED AUDIENCE: Orthopaedic surgeons and orthopaedic residents. 8:00
a.m. Opening Remarks President Hip Society -
Benjamin Bierbaum, M.D. President AAHKS- John
Callaghan, M.D. SYMPOSIUM I: THE OLDER
PATIENT WITH DJD (75 YEARS OR OLDER): ISSUES OF BONE QUALITY AND STABILITYModerators: Richard
Coutts, M.D., San Diego, CA Richard Welch, M.D., San Francisco, CA 8:05 a.m. Basic Science: Osteoarthritis In The Elderly How The Older Patient Is
Different Miguel Cabanella, M.D. Rochester, MN 8:15 a.m. Surgical Approach and THA Dislocation: A Critical Review of the Literature Robert Bourne, M.D. London, Ontario 8:25 a.m. Hip
Implant Selection for Total Hip Arthroplasty In Elderly Patients William L.
Healy, M.D. Burlington, MA 8:35 a.m. Bearing
Surface Variations to Improve Stability Paul Lachiewicz, M.D. Chapel Hill, NC 8:45 a.m. DISCUSSION
SYMPOSIUM II: THE MIDDLE AGED
PATIENT WITH DJD (45 YRS OR OLDER): ISSUES OF
FIXATION , THE BEARING SURFACE AND OSTEOLYSIS Moderators: Richard
White, M.D., Albuquerque, NM Ken Krackow, M.D., Buffalo, NY 8:55 a.m. Basic Science: Fixation:
Lessons Learned from Analysis of Long-Term Cemented Human Retrievals. William Maloney, M.D. St. Louis, MO 9:05 a.m. What We’ve Learned About
Long-Term Cementless Fixation From Autopsy Retrievals Charles Engh, M.D. Arlington, VA 9:15 a.m. The
Case For Proximally Coated Stems. William Capello, M.D. Indianapolis, IN 9:25 a.m. The Case For Extensively Coated Stems In
Middle Aged Patients. Wayne Paprosky, M.D. Winfield, IL 9:35 a.m. Cement
Versus Cementless Fixation In THR. Eduardo Salvati, M.D. New York, NY 9:45 a.m. DISCUSSION 9:55 a.m. BREAK 10:10 a.m. Presidential
Guest Speaker Introduction –
Benjamin Bierbaum, M.D. 10:15 a.m. Guest
Speaker: Philippe Hernigou, M.D.
Creteil, France Treatment Of Osteonecrosis With Autologous Bone Marrow Grafting (From Research To Treatment) SYMPOSIUM III: THE YOUNG PATIENT WITH DDH/EARLY DJDModerators: Richard
Rothman, M.D. Philadelphia, PA Lester Borden, M.D.
Cleveland, OH 10:45 a.m. Basic Science: Natural History of DDH and its effect on
Hip Bio-Mechanics. Stuart Weinstein, M.D. Iowa City, IA 10:55 a.m. Alternative
Treatment for Osteoarthritis of the Hip.
David S. Hungerford, M.D. Baltimore, MD 11:05 a.m. Rationale
And Results Of Osteotomy And Related Procedures For Hip Joint Preservation. Michael Millis,
M.D. Boston, MA 11:15 a.m. The Rationale and Results of Hip
Arthroscopy. Joseph McCarthy, M.D. Boston, MA 11:25 a.m. The Rationale and Results of Surface
Replacement (AVN, DJD) Michael Mont, M.D. Baltimore, MD 11:35 a.m. Rationale, Technique and Results of THR The Young Patient with DDH/Early
DJD.
James D'Antonio,
M.D. Moon Township, PA 11:45 a.m. DISCUSSION 12:00 a.m. LUNCH SYMPOSIUM IV: THE HIP SOCIETY
AWARDS Moderators: Benjamin
Bierbaum, M.D., Boston, MA Joseph McCarthy, M.D.,
Boston, MA 1:00 p.m. OTTO AUFRANC AWARD The Relative Contributions of Surface Chemistry and Topography To the Osseointegration of HA Coated Implants S.A. Hacking Montreal, Quebec 1:15 p.m. JOHN
CHARNLEY AWARD Metal on Metal Versus Metal on Polyethylene Liners in Total Hip Arthroplasty: Clinical and Metal Ion Results of a Prospective Randomized Clinical Trial S.J. MacDonald, M.D. London, Ontario 1:30 p.m. FRANK
STINCHFIELD AWARD Viscosity Effects on Cement Pressurization and
Trabecular Bone Cement Intrusion.
Michael R. Dayton, M.D.
Burlington, VT
SYMPOSIUM V: HEAD SIZE, THE
BEARING SURFACE AND WEAR Moderators: Cecil
Rorabeck, M.D., London, Ontario Merrill Ritter, M.D., Mooresville, IN 1:45 p.m. Basic Science: Fundamental relationships among bearing material,
ball diameter, penetration rate, Volumetric wear, debris morphology and the
incidences of dislocation and osteolysis. Harry McKellop, Ph.D. Los Angeles, CA 1:55 p.m. Osteolysis: A Disease of Access to Fixation Interfaces. Michael Manley, Ph.D. Franklin Lakes, NJ 2:05 p.m. Particles
and Peri-Implant Bone Resorption. Thomas Bauer, Ph.D. Cleveland, OH 2:15 p.m. Intra-Articular
Pressure Differences In Total Hip Arthroplasty. William Lanzer, M.D. Seattle, WA 2:25 p.m. All
Heads Should Be 28 Millimeter or Less: Rationale & Results. John Callaghan, M.D. Iowa City, IA 2:35 p.m. All Heads Can Be 32-mm or Greater with Highly Crosslinked Poly: Rationale and Results. Harry Rubash, M.D. Boston, MA 2:45 p.m. The Bearing Surface Should be
Metal-on-Metal. Lawrence Dorr, M.D. Los Angeles, CA 2:55 p.m. Ceramic On Ceramic Bearings In Total Hip
Arthroplasty. Benjamin Bierbaum,
M.D. Boston, MA 3:05 p.m. DISCUSSION 3:20 p.m. BREAK SYMPOSIUM VI: LATE SEQUELAE OF HIP JOINT TRAUMAModerators: Leo
Whiteside, M.D., St. Louis, MO Clive Duncan, M.D.,
Vancouver, BC 3:35 p.m. Basic Science: Articular
And Bony Changes Following Acetabular Fracture. Marvin Tile, M.D. Toronto, Ontario 3:45 p.m. Anatomic Joint Fracture Fixation and Long
Term Results. Joel Matta, M.D. Los Angeles, CA 3:55 p.m. Total Hip
Arthroplasty For Post-Traumatic Arthritis Following Acetabular Fracture. Daniel Berry, M.D. Rochester, MN 4:05 p.m. DISCUSSION SYMPOSIUM VII: A VIEW AHEAD IN THR (VIDEO VIGNETTES) Moderators: Douglas Dennis, M.D., Denver, CO Clifford Colwell, M.D., LaJolla, CA 4:15 p.m. New Developments from the O.R.S. Richard Coutts, M.D. San Diego, CA 4:25 p.m. Mini-Incision
For Total Hip Replacement. Thomas P. Sculco, M.D. New York, NY 4:31 p.m. Pre-operative Assessment of Hip Dysplasia: Prognosis for Outcome After Periacetabular
Osteotomy Stephen Murphy, M.D. Brookline, MA 4:37 p.m. Surgical Navigation for Hip Surgery. Anthony DiGioia, M.D. Pittsburgh, PA 4:43 p.m. Virtual
Reality of the Hip. Jay Mabrey, M.D. San Antonio, TX 4:49 p.m. DISCUSSION 5:00 p.m. ADJOURN 8:05 a.m. Osteoarthritis
In The Elderly How The Older
Patient Is Different Miguel
E. Cabanela, M.D. As
the longevity of the population increases the number of elderly patients with
coxarthrosis that requires hip replacement continues to increase. Our
trends of utilization of THA in the patient older than 75 years will be
shown. Three
general issues that are of obvious importance in the elderly patient
contemplating a THA need to be addressed: 1)
GENERAL HEALTH Under this heading, hypertension, diabetes and
obesity can affect immediate outcome and need to be evaluated and their
control optimized prior to surgery. Incidence of medical complications in
this group of patients will be contrasted with the general population. Also under this heading neurologic disease, such as
Parkinson’s or prior CVA can influence outcome. In the case of Parkinson with
a shown increase incidence of postoperative pulmonary or urinary tract
infections, but also with a higher risk of postoperative dislocation, a risk
also present with previous CVA. Incidence of general and orthopedic
complications in these situations will be presented. 2)
COGNITIVE Patients in this age range are more likely to
develop postoperative confusion. This is particularly common in patients
afflicted with Parkinson’s disease. Therefore cooperation can not be
anticipated to be as reliable as with younger patients with issues of
positioning in bed or seating and one can not predict how such patient will
be able to ambulate with protected weight bearing. Thus component position
and fixation will have to be optimized in the operating room, expecting a
relatively limited postoperative cooperation. Statistics to support this will
be included extracted from our Joint Registry. 3)
MUSCULOSKELETAL SYSTEM Issues of decreased muscle
and bone mass will influence both our choice of implant (large patulous
femoral canal, osteoporotic pelvis) and our choice of fixation. We still use
occasionally cemented all polyethilene sockets in this aged patients and our
results continue to justify this choice. Cemented fixation of the femoral
stem is also preferred. Decreased muscle mass can
slow down the patient’s functional recovery, but also can be a contributory
factor to increased joint instability (decreased myofascial tension) making
it at times necessary to deliberately elongate the extremity to maximize soft
tissue tension. The alternative, to advance the greater trochanter, is not
desirable in this group of patients. Despite these issues, with proper preoperative preparation, attention to surgical technique and careful postoperative support these elderly patient do tolerate the procedure very well and the results are not different in quality than those obtained in the general population 8:15 a.m. Surgical
Approach and THA Dislocation: A Critical
Review of the Literature John L. Masonis, M.D., Robert Bourne, F.R.C.S.C. Dislocation is the leading
early complication of total hip arthroplasty. The effect of surgical approach
on instability and abductor function remains a controversial topic. A comprehensive
literature review was performed to evaluate the correlation of surgical
approach and primary THA dislocation. 260 clinical studies were identified
between 1970 and 2001. Three prospective studies were identified but
individually contained insufficient power to reach statistical significance
regarding dislocation. 15 studies involving 13,381 primary THA met inclusion
criteria based on variables previously demonstrated to affect stability.
These studies were evaluated with respect to surgical approach and
dislocation. The combined dislocation rate for these studies was 1.46% for
the transtrochanteric approach, 0.72% for the lateral approach, and 3.35% for
the posterior approach. The quality of literature regarding surgical
approach, dislocation rates, and abductor function is limited. Larger
controlled prospective studies are needed to investigate the potential
benefits of the posterior approach in lieu of a dislocation rate almost five
times higher than the lateral approach for total hip arthroplasty. 8:25 a.m. Hip Implant Selection for Total Hip
Arthroplasty In Elderly Patients William L. Healy, M.D. The
population of the United States is increasing and aging, according to the
2000 United States census. The life
expectancy of 75-year-old men and women in the United States is 9.6 years and
12.2 years respectively. The
prevalence of total hip arthroplasty (THA) is likely to increase in the next
decade, and a successful hip replacement in a patient greater than 75 years
of age should relieve pain and improve function for at least ten years. Considerations
regarding hip implant selection for THA in the elderly include: bone quality,
bone morphology, implant fixation, bearing surface wear, and implant
cost. The importance of bone quality
to implant fixation is not clear.
Satisfactory implant fixation in the elderly has been achieved with
both cemented and cementless THA implants, and cementless implants have
demonstrated predictable fixation in octogenarians and in patients with
osteopenic bone. Bone morphology can
affect implant fixation, and femoral shape is more important when selecting
cementless femoral components than cemented implants. Cemented
THA and cementless THA can be successful in the elderly. Following cemented
THA in patients over eighty years old, implant loosening has been reported as
4.2% (3 of 71) at 5 years, 3.7% (6 of 162) at 1 year; and 0 % (0 of 76) at 5
years. Following cementless THA in
patients over 65 years old, implant loosening has been reported as 3% (4 of
135) at 5 years or death, and in patients over 80 years old as 0% (0 of 78)
at 5 years. Bearing surface wear is
generally not a major problem in the elderly due to lower activity levels and
a shorter life span. Conventional
polyethylene articulating with polished cobalt chromium provides a
predictable bearing surface for the elderly patient. Implant
cost is an important issue for hospitals.
In general, hospitals are reimbursed for hip replacement operations by
case price reimbursement. For
Medicare patients the hospital payment for hip replacement is determined by
the Diagnosis Related Group payment system (DRG 209). On January 1, 2002, DRG 209 payment to
hospitals decreased 1.8% to $9,057.
During the 1990's the cost of hip implants became a point of contention
between hip surgeons and hospitals.
Hospitals were in a difficult position of paying for a surgical supply
item selected by a surgeon who had no economic accountability for implant
selection. Hip
surgeons are committed to giving their patients the "best result
possible" from THA. Hip surgeons
should not have to consider implant cost in the operating room. In 2002, the cost of hip implants should
be evaluated, negotiated, and determined in the Board Room, rather than the
operating room. We have had success
with a Single Price/Case Price Hip Implant Purchasing Program. Using a competitive bid process, the
hospital and the hip surgeons selected one implant manufacturer to provide
all hip implants for one single price for each primary THA operation (CPT
27130). The Single Price/Case Price Hip Implant Purchasing Program allowed
the hospital to reduce its cost for hip implant replacement operations and it
allowed surgeons to use any implants they desire within that implant vendor's
inventory for the same price. Consideration
regarding selection of hip implants for THA operations in elderly patients
include: bone quality, bone morphology, implant fixation, bearing surface
wear and implant cost. The goal of
THA in the elderly is to relieve pain and improve function for the rest of
the patient's life. This goal can be
successfully achieved with cemented and cementless implants, which are
inserted with precise, accurate surgical technique. In my practice in 2002, I use a modular, porous coated titanium
alloy acetabular shell with screw fixation and a conventional polyethylene
acetabular liner. I use a modular,
flat tapered femoral component without a collar with proximal circumferential
porous coating made of cobalt chromium, or titanium and a polished 28-mm.
femoral head made of cobalt chromium.
The price of the implants is negotiated through a Single Price/Case
Price Implant Purchasing Program so I do not have to consider implant cost in
the operating room. 8:35
a.m. Bearing Surface Variations to Improve
Stability Paul F. Lachiewicz, M.D. Increasing patient age is a known risk factor for dislocation of total hip arthroplasty, with rates of 1 to 10% reported in the older population. Dislocation has been reported in 8.7% of hips with cemented all-poly acetabular components in patients ≥ 75 years with osteoarthritis and in 1-5% of hips with modular cementless acetabular components The use of bipolar arthroplasty in this population has a lower rate of dislocation (1.5%), but there are problems with residual pain and high rates of reoperation, wear and osteolysis. Bipolar arthroplasty may be a useful salvage for recurrent dislocation. Constrained components may be indicated in the older patient for recurrent dislocation associated with dementia, trochanteric non-union - abductor insufficiency or failure of modular revision. The reported rate of failure of these devices ranges from 4% (tripolar) to 9-29% (snap-fit, locking ring). Larger (36, 38 and 40 mm) femoral heads may be implanted with highly cross-linked acetabular liners, which have greatly decreased in-vitro wear even with larger femoral heads. Although these components will allow greater range of motion before dislocation, there is no clinical data yet available. The author has performed 146
primary total hip arthroplasties in patients ≥ 75 years. Of 140 with a minimum 1-year follow-up,
there were 100 in females and 40 in males and the preoperative diagnosis was
osteoarthritis in 82%. The mean follow-up time was four years. The acetabular
component was modular-cementless in 121 hips and cemented in 19. There were
five dislocations (3.5%), but only two were recurrent, and successfully
treated by modular exchange. In our study of 17 modular revisions for
recurrent dislocation, the procedure was successful in 82%.
Modular-cementless acetabular components appear to be preferable for total
hip arthroplasty in patients ≥ 75 years. A 28 or 32 mm femoral head is used, but larger heads should be
considered in fracture patients and in the treatment of recurrent
dislocation. Modular exchange has a reasonable rate of success for recurrent
dislocation if acetabular component position is satisfactory. 8:55 a.m. Fixation:
Lessons Learned from Analysis of Long-Term Cemented Human Retrievals William
J. Maloney, M.D., Thomas Schmalzried, M.D. and William H. Harris, M.D. A detailed biomechanical, histological and histomorphometric analysis
of autopsy specimens from patients who had previously undergone cemented
total hip arthroplasty have help to elucidate the skeletal response to
cemented components. Bone cement has
the capacity to provide long-term implant stability. However, the biological response to
polyethylene wear debris has a more critical effect on destabilization of
cemented acetabular stability when compared to the femoral side. In contrast, mechanical events tend to
predominated the early mode of destabilization of cemented femoral components
with debonding at the metal-cement interface as well as fracture in the
cement itself. Fractures predominate
in cement mantles less than 1 millimeter thick and are associated with mantle
defects, debonded interfaces and sharp corners of the implants. Correlation of the histologic findings at
the cement-bone interface with radiolucencies found on clinical radiographs
demonstrate that on the acetabular side radiolucencies represent
interposition of a soft tissue membrane that represents the biologic response
to polyethylene debris. In contrast,
on the femoral side, most radiolucencies were as a result of skeletal
remodeling. Quantification of the
adaptive remodeling process in the femur demonstrates that remodeling is a
diffuse process that occurs over the entire fixation surface. The most profound disuse osteoporosis
occurred in the proximal medial quadrant however when one takes into account
all four quadrants, anterior, posterior, medial and lateral, the most severe
osteoporosis actually occurred at the midpoint of the stem. Overall, the degree of bone remodeling
correlates the bone-metal density of the contralateral femur. The less dense the bone is before hip
replacement, the greater the extent of bone loss after replacement. 9:05
a.m. What We’ve
Learned About Long-Term Cementless Fixation From Autopsy Retrievals Christi J. Sychterz, M.S.,
Alexandra M. Claus, M.D., PhD., Charles A. Engh, M.D. This paper
summarizes insights gained from the authors’ experience studying uncemented
porous-coated femoral and acetabular hip replacement components retrieved at
autopsy. For femoral components, autopsy studies demonstrated that
osseointegration occurs over an average 35% of the porous surface with the
most predictable ingrowth occurring near the termination of the porous
coating. The bone ingrowth pattern
causes a predictable bone remodeling pattern: an overall decrease in bone
mineral content (mean 23% loss) occurring on a gradient with most loss
proximally and the least distally. This pattern occurs regardless of the
implant’s level of coating, mirrors the gradient of strain reduction, and
because it is easily recognized, can be used by orthopaedists to identify
bone ingrown components on standard radiographs. Studies have also shown that
femoral bone loss is more related to the characteristics of the implanted
femur than any other variable. Histologic evidence demonstrated that
circumferential porous coating protects against the migration of polyethylene
wear debris to distal locations along the length of the femur and around
acetabular components. On the acetabular side, bone ingrowth is more
unpredictable and occurs randomly. Although the amount of bone ingrowth
averaged 32%, it ranged from 3 to 84%. Unfortunately, a consistent pelvic
remodeling pattern has not been associated with an implanted porous-coated
uncemented cup. Consequently, orthopaedists cannot determine radiographically
whether an acetabular component is truly bone ingrown. Overall, autopsy
studies have contributed to a basic understanding of the histological and
resultant radiographic appearance of osteointegrated porous-coated implants,
and confirmed the durability of this three-dimensional fixation even in the
presence of osteolysis. 9:15
a.m. The Case for
Proximally Coated Stems William N. Capello, M.D. The
aim of research in total hip arthroplasty (THA) is to extend the longevity of
implants in situ. Pertinent issues
are implant design, fixation, and reduction of wear debris and subsequent
osteolysis. Total hip arthroplasties
are being performed in older and younger age groups than were done a decade
ago, however the preponderance of those undergoing THA remains the middle
aged individual (45 years and older) with DJD. This report will focus on clinical and radiographic results of
a prospective, multicenter study of a proximally hydroxyapatite (HA) coated
femoral component (Omnifit-HA stem, Osteonics Corporation, Allendale,
NJ). Within this large study group,
229 hips in 201 patients were implanted in patients aged 45 years and older,
have a diagnosis of DJD, and have a minimum ten-year follow-up. Average age of this subgroup of patients
is 56 years (range, 45 - 73), and 53% are male. Clinically,
the average Harris Hip Score is 91 with 95% reporting no or mild hip pain and
no cases of activity-limiting thigh pain.
Four stems have been revised, one each due to aseptic loosening, pain,
deep joint infection, and one well-fixed done in conjunction with cup
revision. There are no
radiographically loose stems.
Proximal femoral osteolysis confined to zones one or seven is seen in
38% of cases with no cases of intramedullary osteolysis. Thirty-one cups have been revised, 19 due
to aseptic loosening, nine due to excessive polyethylene wear and/or
osteolysis, and one each for recurrent dislocation, pain, and deep joint infection. In
summary, this proximally HA coated stem has provided excellent long-term
stability with a mechanical failure rate of 0.4% at 10 to 14 years
post-implantation. This implant seals
the femoral canal from distal egress of wear particles, but polyethylene wear
remains a threat to the integrity of the greater and lesser trochanters and
the acetabulum. As a result, we are
currently involved in a large, multicenter FDA study pairing this stem with
an alumina ceramic-on alumina ceramic bearing surface. At two-year minimum follow-up, there have
been no complications with regard to the ceramic bearing surface, no cortical
erosions, and no stems revised for aseptic loosening. If this stem performs as it has in the
long-term study and the alumina ceramic-on- alumina ceramic bearing surface
reduces wear as has been shown in laboratory and earlier clinical studies,
the issue of implant longevity may be no longer be a primary concern in THA. 9:25
a.m. The Case For Extensively Coated Stems In Middle Aged Patients Wayne G. Paprosky, M.D.,
F.A.C.S. Cemented total
hip arthroplasty in patients under 45 years of age in the long term has shown
high revision rates at long-term follow-up. Cementless acetabular and femoral
fixation in this age group has been very successful with 0 to 4.0% loosening
rates. However, an increased incidence of osteolysis has been associated with
these implants (8-28%). Most patients under 45 have bone quality conducive to
cementless fixation. We have looked at cementless femoral fixation,
osteolysis and bearing surfaces in the middle-aged group using extensively
coated femoral components. This
study examines a consecutive series of patients between 45 and 65 years of age
who underwent total hip arthroplasty with various designs of acetabular
components combined with a cementless extensively coated femoral component. A
retrospective analysis was undertaken of 164 patients who underwent 186
consecutive primary cementless total hip arthroplasties between 1984 and
1989. Ten patients were lost to
follow-up leaving 174 hips in 154 patients. The average age at the time of
surgery was 57 years old. There were
56% females and 44% males. From 1984 to 1985, non-modular AML's were used
with 32mm heads (N=84). From 1986 to 1989 modular heads were used. Thirty-two
stems had 32mm. diameter heads (26 cobalt chrome and 6 ceramic). The rest
were 28mm. heads (27 chrome cobalt and 31 ceramic). The different acetabular
designs were assessed as well as polyethylene thickness. The overall
pain and walking scores improved significantly using a modified D'Aubigne and
Postel score. The results were 83% excellent, 11% good, 4% fair and 2% poor.
Thigh pain was noted in 6-8% of the patients. There were 15% revisions of the
acetabulum for dislocation, lysis or loosening. According to Engh's criteria,
93% of the stems had bony ingrowth and there were 2.9% stable fibrous and
0.8% were loose. The loose stem was infected. There were 19.6% with acetabular
and femoral lysis noted. There
does not seem to be any effect of age or bone type on femoral fixation using
fully porous coated stems. There is a higher acetabular failure rate and more
osteolysis with 32mm. heads. There does not seem to be any difference in
wears pattern and osteolysis between 28mm. ceramic or chrome cobalt heads. We
highly recommend the use of extensively coated stems in the middle age group. 9:35
a.m. Cement Versus Cementless Fixation In THR Eduardo A. Salvati, M.D. The table demonstrates the approximate number of primary total hip replacements (THR) and
the variation every five years in the percentage of cemented, cementless and
hybrid fixation utilized at The Hospital for Special Surgery, from 1985 to
2001. Senior surgeons prefer hybrid fixation, while a few of the younger
surgeons favor cementless fixation, particularly for the young, active
patient. HSS 1985 1990 1995 2001 THRs
(#) 800 1100 1400 1600 Cemented
(%) 100 50 25 5 Cementless
(%) 0 20 15 15 Hybrid
(%) 0 30 60 80 CEMENT FIXATION A properly designed and
well-fixed cemented cup and stem will have a long-lasting successful result.
We implanted our first Charnley THR at The Hospital for Special Surgery in
1968. Callaghan et al.(1) reported the 25 year minimum follow-up
of 327 Charnley THRs in a population whose average age at the time of surgery
was 65 years: 90% retained both prosthetic components until last follow-up or
death. Of the 25 year survivors (62 hips), 77 % retained the original prosthesis. A common factor of the long-term survivors was the
low average linear wear (0.1mm/year), suggesting ideal tribology. The thick
polyethylene and the 22 mm head contributed to the long-term success.
However, young, active, males demonstrated a 0.3 mm/yr linear wear and
required earlier revision surgery.
Likewise, patients with hypoplastic acetabulae (congenital dislocation
or dysplasia) only accepted a thin poly cup and experienced a higher failure
rate.(2) In
the 1980s, metal-back cups were introduced based on finite element studies
that predicted a better transfer of load. However, the clinical experience
demonstrated a 37% increase in mean polyethylene wear and a higher incidence
of loosening, in comparison to all poly cups.(3) Reduced linear wear was
also observed with molded poly in comparison with machined poly (0.05 vs 0.11 mm/yr).(4) UNCEMENTED
CUPS Our experience with modular, uncemented cups
started in the mid 1980s. The press-fit fixation, obtained under-reaming by 2
mm, is consistently good and long lasting. While we used adjuvant screw
fixation during our early experience, during the last decade we have limited
screws to special situations such as dysplastic acetabulum with insufficient
superolateral coverage, protrusio with a deficient medial wall, markedly
cystic acetabulae and postraumatic deformities. Our main concern with cementless modular cups is
the increasing incidence of osteolysis, which varies from 10 to 20% at 10
year follow-up. This complication, due to the generation of particulate
debris from both the articulating and non-articulating surface of the
polyethylene,(5) is not limited to a particular design as we have
observed it with multiple types of modular cups. It is a clinically “silent”
process and by the time the hip becomes symptomatic it is usually evident
radiographically. MRI can further define the location and extent of the
osteolysis and periprosthetic soft tissue swelling.(6), which are
usually more severe than conventional radiographs demonstrate. Another complication we have observed at
intermediate follow-up is the dislodgment of the plastic liner due to the
failure of the locking mechanism and/or plastic deformation and wear of the
polyethylene liner. (7) Overall, the linear wear of modular cups is
higher than that observed with all-poly cemented cups (0.2 vs 0.1mm/yr,
respectively). The plastic liner is thinner in modular uncemented
cups to accommodate the thickness of the metallic shell. Thus, we recommend
selecting smaller heads to maintain a minimum plastic thickness of 8 mm. We
also prefer cups with no holes to increase the surface for bone ingrowth and
the contact area between the backside of the liner and the metallic shell.
Furthermore, cups with no holes prevent the access of particulate debris from
the non-articulating surface to the acetabulum, via the holes.(5)
The backside of the liner must be congruent with the metal shell and the
metallic surface should be polished to minimize abrasion and generation of
particulate debris. The importance of an adequate locking mechanism cannot be
overemphasized.(7,8) Most of the problems outlined are inherent to the
first generation of modular uncemented cups. While it is conceivable that the
second generation will fare better, a report by Sychterz, et al.(9) demonstrated no
improvement in the rate of linear wear between first and second generation
modular cups at mid-term follow up. The detrimental effect of third body wear
is recognized.(10,11) Reference: 1.
Callaghan,
JJ, Albright, JC, Goetz, DD, et al: Charnley total hip arthroplasty with
cement. J.
Bone Joint Surg. 82A:487-497, 2000 2.
DiFazio,
F, Shon, WY, Salvati, EA, Wilson, PDJr. Long-term results of total hip
arthroplasty with a cemented custom-designed swan-neck femoral component for
congenital dislocation or severe dysplasia. J.
Bone Joint Surg. 84A:204-7, 2002 3.
Cates,
HE, Faris, PM, Keating, M., Ritter, MA.:
Polyethylene wear in cemented metal-backed acetabular cups. J. Bone Joint Surg.
75B:249-253, 1993 4.
Bankston,
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machined versus molded polyethylene. Clin. Orthop 317:37-43, 1995 5.
Huk,
O., Bansal, M., Betts, F., Rimnac, CM, Lieberman, JR, Huo, MH, Salvati,
EA: Polyethylene and metal debris
generated by non-articulating surfaces of modular acetabular components. J. Bone Joint Surg. 76B568-574, 1994 6.
Potter,
HG, Sofka, CM, Peters LE, Nestor, BJ, Salvati, EA: MRI in total hip
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Second-Generation Harris-Galante Acetabular Components. J.
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Sychterz,
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Analysis of temporal wear patterns of porous-coated acetabular
components: Distinguishing between true wear and so-called bedding-in. J. Bone Joint Surg. 81A:(6):821-830, 1999 10.
Hop,
JD, Callaghan, JJ, Olejniczak, JP, et al: Contribution of cable debris
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Clin. Orthop. 344:20-32, 1997 11. Morscher, EW, Hefti, A.,
Aebi, U: Severe osteolysis after
third-body wear due to hydroxyapatite particles from acetabular cup
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Bone Joint Surg. 80B:267-272, 1998 10:15
a.m. Treatment Of Osteonecrosis With Autologous
Bone Marrow Grafting (From Research To Treatment) Philippe Hernigou, M.D. Association of
core decompression with addition of bone graft is frequent and many different
techniques have been described. In this series grafting was done with
autologous bone marrow obtained from the iliac crest of patients operated for
hips osteonecrosis. The results of a prospective study of 189 hips in 116
patients treated with core decompression and autologous bone marrow grafting
are reported in this study. Patients were followed up from 5 to 10 years. The
outcome was determined by the changes in the Harris hip score, by progression
in radiographic stages and by the need of hip replacement. The
bone marrow was harvested under general anaesthesia. The usual sites were the
anterior iliac crests. A bevelled metal trocar of 6 - 8 cm length and a bore
of 1.5 mm was pushed deep into the cancellous bone. A 10 mL syringe that has
been flushed with heparin is used to aspirate the marrow. Once the needle has
been inserted to the desired depth, the tip is swept around a full circle in
45° steps, with the bevel pointing in different directions at each step. Bone
marrow is withdrawn at each of these points. Once this 360° aspiration has
been performed at one site, the needle is brought out and reinserted at a
different site, where the 360° sweep in 45° steps is repeated. This procedure
is continued until a sufficient quantity of bone marrow has been harvested
(150 mL). The same percutaneous tract may be used for multiple punctures of
the iliac crest. All the marrow aspirated is discharged into a plastic
collection bag containing ACD (acid citrate dextrose) anticoagulant solution.
It is then filtered, to remove fat aggregates and clots. The aspirated marrow
was reduced in volume by concentration and injected in the femoral head after
core decompression with a small trocar. When patients were operated on before
collapse (stage I and II), hip replacement was performed in 9 of the 145
hips. THR was necessary in 25 hips among the 44 hips operated after collapse
(stage III and stage IV). To
measure the number of progenitor cells transplanted, we used the fibroblast colony
forming unit as an indicator of the stroma cell activity and performed in
vitro cultures of the fibroblast progenitor cells. The average volume of bone
marrow aspiration was 147 mL ± 12 mL per hip. The number of progenitor cells
was average 12.4 ± 3.4 per 106 bone marrow nucleated cells and the
number of nucleated cells was estimated to be 16.4 millions cells per mL of
bone marrow. Patients who had the greater number of progenitor cells
transplanted in their hips had the better outcome. While
fundamental research and clinical studies have shown that dead bone may be
repaired by living bone, the reparative osteogenic potential is slight in
osteonecrosis. At this time using progenitor cells may be one of the
solutions to improve this reparative process. 10:45
a.m. The Natural
History of DDH and it Effect on Hip Biomechanics. Stuart L. Weinstein, M.D. For normal
development of the hip joint to occur, there must be a delicate, genetically
determined balance between growth of the acetabular and triradiate cartilages
and a well-centered femoral head.
This balance may be profoundly affected by the intrauterine
environment. Without treatment, it is
uncertain how many dysplastic, unstable hips will retain their dysplastic
features throughout life. The natural
history of untreated complete dislocation varies considerably and is affected
by societal considerations. There may
be little, if any, functional disability in many cases. Significant roentgenographic degenerative
disease and poor clinical results, however, may develop in completely
dislocated hips with well developed false acetabulae. In unilateral cases, ipsilateral knee
deformity and pain may develop.
Congenital subluxations have a particularly poor long-term
outcome. A significant percentage of
these patients have roentgenographic degenerative joint disease and clinical
disability. The age of symptom onset
and roentgenographic degenerative joint disease is related to the amount of
subluxation and dysplasia. The
natural history of acetabular dysplasia in the absence of subluxation is
difficult to predict. Physical signs
may be absent, and the diagnosis only established with symptom onset or as an
incidental roentgenographic finding.
While degenerative joint disease may ensue, current roentgenographic
parameters are not predictive. The reasons for degenerative changes in
dysplastic hips are probably mechanical in nature and related to increased
contact stresses with time. A certain "over pressure" may correlate
with long term outcomes with aspherical heads having even worse outcomes.
Degenerative joint disease in hip dysplasia correlates with the magnitude of
the "over pressure" and the length of exposure. 10:55 a.m. Alternative Treatment for
Osteoarthritis of the Hip
David
S. Hungerford, M.D. Many
of our most important pharmaceuticals have their origin in plants, such as
digoxin, penicillin, and coumadin. However, many physicians are deeply
skeptical about the use of natural remedies. This skepticism is based on the
concerns about patient self-diagnosis and treatment as well as the lack of
scientific testing of claims. Nonetheless, a new class has emerged called
nutraceuticals - nutritional supplements with pharmaceutical properties.
Because these substances are relatively unregulated there is no requirement
for rigorous scientific testing prior to marketing. This lack of regulation
also poses problems with purity and quality control. Even so, patients are being
bombarded with, and responding to, claims of the results of the use of herbs,
nutraceuticals, and nutritional supplements. Glucosamine and chondroitin sulfate sales alone in the
U.S. are estimated at $600 million. Sales of all nutraceuticals and vitamin
supplements in the U.S. exceeded 12 billion dollars in 1999. Many physicians
took offense at the title of the book by Theodosakis et al., The Arthritis
Cure, because they know no cure exists. That offense translated into
discounting the very reasonable recommendations in the book. Patients, on the
other hand, pushed sales of the book to the bestseller list. Moreover, glucosamine and
chondroitin sulfate have been widely studied in tissue culture, animal models
of arthritis, veterinary clinical trials, and human comparative or placebo
controlled trials. No published study has failed to show a positive effect
and no trial has shown significant side effects. These nutraceuticals have
become our first line of treatment for osteoarthritis. 11:05
a.m. Rationale And
Results Of Osteotomy And Related Procedures For Hip Joint Preservation Michael B. Millis, M.D. Most
osteoarthrosis of the hip results from chronic abnormal hip mechanics, often
associated with instability, impingement, or combinations of instability and
impingement The site of earliest articular damage usually is the acetabular
rim, as noted first by Ganz and co-workers.
The etiology of the mechanical problem in many hips is a surgically
treatable anatomic abnormality, often a developmental deformity (DDH, Perthes
disease, slipped epiphysis, or femoral/acetabular retroversion). The rationale of
mechanically-based measures to prevent osteoarthrosis assumes that there is
an initial stage of primary deformity during which there is mechanical overload
of the joint which would, if not corrected in timely fashion, would lead to
OA. Correction of the primary
deformity, to a degree that brings joint contact pressures within tolerable
limits and eliminates instability and impingement before irreversible
articular damage has occurred, seems to accomplish this goal in congruous
acetabular dysplasia and in slipped capital femoral epiphysis. An important step in
preventing and effectively treating arthrosis-producing hip conditions lies
in understanding the pathomechanics of each particular deformity. In DDH, acetabular
obliquity and instability create shearing forces and chronic overload of the
anterior and anterolateral acetabular rim, which leads to frequent fatigue
failure in the third or fourth decade of the labrum or the bony acetabular
rim. In SCFE, impingement of the
anterior metaphyseal prominence at the head-neck junction can cause a variety
of impingement lesions of the anterior acetabular labrum, bony rim, and
adjacent anterior acetabular articular cartilage. In Perthes disease and
osteonecrosis, somewhat similar impingement syndromes are frequently found. In males, many hips with
less-than-normal femoral and acetabular anteversion, often with a reduced
femoral head-neck offset, develop stiffness and arthrosis in the fourth
decade of life. Anterior impingement
seems to be the mechanical lesion in these hips, too. Correction of the
mechanical hip problem before the development of arthrosis is the goal of the
joint-preserving surgeon, since the results in published series of joint preserving
operations confirms that the quality of long-term results correlates
inversely with the amount of arthrosis present at the time of the
intervention. In acetabular dysplasia,
where OA will occur in almost every hip left untreated with a C-E angle of
less than 20 degrees, the best long-term result requires the establishment of
a stable joint, without impingement, usually achieved best by acetabular or
periacetabular osteotomy A congruous articulation, intraoperative flexion of
at least 90 degrees, and a horizontal sourcil are desirable. In such hips where preop arthrosis is
grade 0 or 1, 10 year good-excellent results are at least 85-90%. In slipped epiphysis, there
has been incomplete historical understanding of the importance that
impingement plays in the development of arthrosis. Until the recent development of new generation MR cartilage
imaging techniques (radial sequences), impingement has been difficult to diagnose.
In addition, safe and surgical methods to relieve impingement have only
recently become known, as Ganz and others have refined the technique of surgical
dislocation to allow precise osteoplasty, intraarticular debridement, and
proximal femoral realignment with minimal risk of osteonecrosis. In
the non-SCFE
retroversion syndromes relief of impingement also is the essence of
joint-preserving treatment.
Osteoplasty, joint debridement, and osteotomy-alone and in
combination-are accomplishing maintenance and recovery of joint function
never seen before.
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