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2007 Advances in total hip and total knee replacement surgery
As the year 2007 concludes the Arthritis Institute gives blessings for the
following advances in total hip and total knee replacement surgery, some of
which it's research contributed to:
The posterior minimally invasive surgery technique (developed in part by Dr.
Dorr) had the best evidence-based medicine results of all published results
of small incision surgery.
Pagnano and colleagues from the Mayo Clinic in Rochester, Minnesota
compared, in randomized prospective studies, Dorr's posterior operation to
an anterior “no muscle cut” approach (two incisions) and found better
recovery times and better patient satisfaction with the posterior small
- Pagnano MW, Trousdale RT, Meneghini RM, Hanssen AD. Patients preferred
a mini posterior THA to a contralateral two-incision THA. Clin Orthop
Relat Res. Dec 2006;453:156-159.
- Pagnano MW, Trousdale RT, Meneghini RM, Hanssen AD: A randomized
clinical trial shows that 2-incision total hips do not recover faster
than mini-posterior total hips. J Bone Joint Surg Am 2008:
The anterior “no muscle cut” operation had no better muscle function at
six weeks and three months postoperative compared to the posterior
incision, as measured by gait analysis (walking studies).
- Malik A, Dorr LD. The science of minimally invasive total hip
arthroplasty. Clin Orthop Relat Res. Oct 2007;463:74-84.
- Comparison of Gait Analysis Results Preoperatively at 6 Weeks and 3
Months in Relation to Different Surgical Approaches*
||(N = 11)
||(N = 10)
||(N = 18)
||(N = 30)
|Preoperative SS velocity
||60.6 ± 2.4
||62.8 ± 3.4
||56.9 ± 2.1
||62.8 ± 1.3
|6-week SS velocity
||62.3 ± 6.6
||54.4 ± 9.8
||61.4 ± 13.0
||66.5 ± 13.5
|3-month SS velocity
||71.5 ± 7.9
||63.8 ± 10.8
||69.1 ± 11.9
||69.2 ± 11.1
|Preoperative FST velocity
||81.7 ± 5.3
||70.6 ± 2.6†
||69.9 ± 4.2†
||80.4 ± 3.9
|6-week FST velocity
||80.0 ± 8.6
||72.6 ± 7.1
||71.8 ± 18.4
||77.1 ± 14.5
|3-month FST velocity
||91.8 ± 14.8
||82.7 ± 19.6
||81.8 ± 19.8
||82.7 ± 13.8
*Mean ± standard deviation; †significantly different from
anterolateral MIS; MIS = minimally invasive surgery; SS = self-selected
velocity; FST = fast velocity
At 6 weeks and 3 months postoperatively, there were no differences
between groups in terms of velocity, cadence, stride length, single-limb
support time, or double-limb support time. The amount of surgical soft
tissue trauma appeared not to change the recovery of postoperative gait
Our research with a randomized blinded prospective study, in which our patients
participated, proved posterior minimally invasive surgery had less pain and
faster recovery than a posterior long incision.
Dorr LD, Maheshwari AV, Long WT, Wan Z, Sirianni LE. Early pain
relief and function after posterior minimally invasive and
conventional total hip arthroplasty. A prospective, randomized,
blinded study. J Bone Joint Surg Am. Jun 2007;89(6):1153-1160.
There were no evidence-based scientific comparative studies showing
benefits of any anterior (“no muscle cut”) operation.
Our conclusion is that surgeons who operate anterior, and do so well,
should use that operation. However, any claim that the anterior "no
muscle cut" operation is less invasive, or provides better recovery,
have no scientific basis and should be considered only marketing
The patient care model of the Arthritis Institute has been studied by
several visiting orthopedic surgeon groups. This model is unsurpassed in its
patient results which have been published.
First, the pain management is the best program yet developed for total
hip and total knee recovery according to published results. The average
pain score of total hip patients on discharge is between 1 and 2 on a
scale of 10.For knees, it is between 2 and 2.5.Vomiting occurs in only
1-3% of patients. For results see:
- Dorr LD, Long WT. Multimodal analgrsia without parenteral narcotics
for total knee arthroplasty. J Arthroplasty. In press.
- Maheshwari AV, Boutary M, Yun AG, Sirianni LE, Dorr LD. Multimodal
analgesia without routine parenteral narcotics for total hip
arthroplasty. Clin Orthop Relat Res. Dec 2006;453:231-238.
There have been no deaths from pulmonary embolism in this decade among
patients from the Arthritis Institute.The occurrence of a symptomatic
blood clot is 0.4%, and most occur in patients with a history of
previous blood clots. This data is published in:
- Dorr LD, Gendelman V, Maheshwari AV, Boutary M, Wan Z, Long WT.
Multimodal thromboprophylaxis for total hip and knee arthroplasty
based on risk assessment. J Bone Joint Surg Am. Dec
With hip replacement we have six infections in 2053 primary total hip
replacements (0.3%) since 2001. With knees we have 9 infections in 2199
primary total knee replacements (0.4%) in the same time period.
Our nurses had no documented medical errors in caring for our
postoperative patients in 2007.Home physical therapy visits by our
therapists, (who have also cared for the patients in the hospital)
improved recovery. These nursing care and physical therapy recovery
programs for our patients are not exceeded by published data from any
joint replacement center.
The Durom (Zimmer) large head metal-on-metal articulation surfaces have had
worse results than metal or ceramic heads articulating with highly
crossed-linked polyethylene. There has been more pain and more revision of
cups, both in our experience and internationally. The best results have been
with the Birmingham metal-on-metal articulations. We have also had good
results with the Biomet metal-on-metal articulation surfaces.
Our experience with the Durom large head metal-on-metal articulation shows
5% revision within one year of operation. This may be caused by
hypersensitivity to metal-on-metal or poor fixation of the cup design. The
Australian Registry shows failure of Durom (Zimmer) at 4-5% and the ASR cup
(Depuy) at 4-5%. The Birmingham cup has failure less than 1%.
Dr. Long continues to use metal-on-metal articulations of Biomet and has
advised Zimmer to redesign the Durom metal-on-metal cup with a hemisphere
shape and add hydroxyapatite to its surface to improve fixation.
A predictable articulation that seems to be the most comfortable at this
time is ceramic or metal against highly cross-linked polyethylene. The wear
is so low with this articulation that a total hip replacement can be
expected to last 25-30 years when performed correctly with these materials.
Highly crossed linked polyethylene is also used by the Arthritis Institute
for total knee replacement.
- Dorr LD, Wan Z, Shahrdar C, Sirianni L, Boutary M, Yun A. Clinical
performance of a Durasul highly cross-linked polyethylene acetabular liner
for total hip arthroplasty at five years. J Bone Joint Surg Am. Aug
- Wan Z, Boutary M, Dorr LD. The influence of acetabular component position
on wear in total hip arthroplasty. J Arthroplasty. In Press.
The use of computer navigation has provided consistently predictable and
reproducible results for the surgeons at the Arthritis Institute. Dr. Dorr
has developed the computer software program for total hip replacement with
Orthosoft which was recently purchased by Zimmer. This computer program
allows accurate placement of the femoral and acetabular components to mate
the two in the correct position to minimize wear and maximize stability.
The leg length of the hips can be most accurately measured with the
computer. The offset of the hip, which is the relationship of the femur to
the pelvis, can also be most accurately measured with the computer.
Therefore, computer navigation for the hip has been shown by studies
published by the Arthritis Institute to be better than what even an
experienced surgeon can produce using his experience and judgment, or
- Dorr LD, Malik A, Wan Z, Long WT Precision and Bias of
Imageless Computer Navigation and Surgeon Estimates for Acetabular
Component Position. Clin Orthop. 465:92-99, December 2007.
- Dorr LD, Malik A, Wan Z. Combined Anteversion Technique for Total Hip
Arthroplasty. J Bone Joint Surg. In Press
- Zhu J, Wan Z, Dorr LD. Effect of pelvic tilt on acetabular componenet
placement in total hip arthroplasty. J Bone Joint Surg. In Press.
Dr. Long also use the computer navigation for total knee
replacement.Dr. Long has refined this technique so it is a very simple and
not a time consuming technique which verifies the position of the implants
to allow predictable mating of the implants in the knee, just as the
navigation allows predictable mating of the implants in the hip. This will
improve tracking of the implants which improves range of motion, comfort,
Total knee replacement continues to be a durable operation with results
expected to last, like hips, 25-30 years. The comfort of total knee
replacement, in our patients, has improved with the use of the new gender
based designs which have been modified to fit the bone better, improve
patella tracking, and improve range of motion. Our prospective study is in
the final six months of patient followup (some of the patients at the
Arthritis Institute are included in this study). The design we use most
often is the Natural Knee and sometimes the NexGen knee, both manufactured
by Zimmer. Dr. Dorr has participated in the design teams for both the
Natural knee and NexGen gender knee designs. We do not use mobile bearing
knees, as marketed by Johnson and Johnson DePuy, because there is no
evidence-based improvement in results, performance, or durability for at
least as long as 10 years postoperative. They cost $2,000 to $3,000 more and
therefore inflate healthcare costs without any known benefit.
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