A Comparison Between MIS and Traditional
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Body: A Comparison Between Minimally Invasive and Traditional
Total Hip Replacement
Incision Size
MIS 2-Incision Hip Replacement vs. Traditional Surgery
Zimmer MIS
Zimmer MIS 2-
Anterolateral Hip Incision Hip
Procedure
Incision
Tissue
Trauma
Procedure
Zimmer MIS
Traditional Hip
Posterior Hip
Replacement
Procedure
One 2 ½ -3 ½ inch Two 1 ½- to 2- One 2 ½ - to 3 One 10- to 12-inch
incision
inch incisions
½-inch incision
incision
Muscles and
Muscles and
Fewer muscles More muscles and
tendons avoided
tendons
and tendons cut
tendons cut or
avoided
or separated
separated
Figure I: A comparison between traditional and minimally invasive incision size
Source: Zimmer, Inc. 2007
When comparing minimally invasive and traditional hip surgeries, patients
generally place great emphasis on the size of the incision(s). During a traditional total
hip replacement, an incision approximately 10-12 inches long is made on the side of the
hip. Once the incision is made, the surgeon then cuts through the muscles to detach them
from the hip joint itself (Minimally Invasive Total Hip 2007). This cutting of the muscles
A Comparison Between MIS and Traditional
allows the surgeon to access the affected hip joint, remove the damaged/diseased parts,
and insert the artificial components of the new hip joint.
In comparison, when a minimally invasive hip replacement surgery is being
performed, surgeons perform the same hip replacement surgery through either one
(usually a 3 to 6 inch incision on the outside of the hip) or two (generally a 2 to 3 inch
incision around the groin area and a 1 to 2 inch incision in the buttock region) smaller
incision(s). The muscles that surround the hip joint still need to be detached and
separated but they are not traumatized as much as they may be with a traditional
approach (Minimally Invasive Total Hip 2007).
Incision size is an important factor to consider when comparing the two methods
of surgery, as it is believed that minimally invasive surgery with smaller incisions may
result in less pain following surgery, scars that may be more “cosmetically appealing”
and less disfiguring, less muscle damage during the surgical procedure, and less blood
loss during surgery as compared with a more traditional approach (Minimally Invasive
Total Hip 2007).
Various research examining the possible pros and cons of different incision sizes
has been conducted. One study by Wright et al investigated the possible benefits of a
“mini-incision” for a total hip replacement procedure as compared with a much longer,
traditional incision. The group of patients that took part in hip replacement surgery with
smaller incisions were very happy and excited with the fact that the incisions were more
“cosmetically appealing”; however, this particular study showed no definite benefits to
the smaller incisions aside from “cosmetic appeal” (Wright 2004).
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In a similar study carried out by de Beer et al, one group of patients received total
hip replacements through a single 10 cm long incision and another group received the
same surgery through a standard length incision. The results of this study could not
prove that there was any significant difference between the two groups in the following
areas: length of operation, medications required while the patients were in the hospital,
blood that was lost as a result of surgery, complications following surgery, length of
hospital stay, or measurements of specific motions of the hip following surgery (de Beer
2004).
These findings are just a few examples expressed in the current research regarding
this particular topic; however, a good portion of the results of these studies are rather
inconclusive. Although smaller incisions are more appealing cosmetically following hip
replacement surgery, it has yet to be proven that they have any long term clinical benefits
as compared to traditional length surgical incisions. Another interesting point that has
been brought up in the research is the fact that the smaller incisions create some
additional challenges when it comes to hip replacement surgery. The same procedure is
being performed through a smaller incision, and the surgeons do not have the ability to
see the hip joint area completely. With limited exposure of the hip anatomy and a
smaller visual field, the risk for potential problems and complications both during and
after surgery may increase. According to the American Association of Hip and Knee
Surgeons, possible disadvantages to performing hip replacement surgery through a
limited area include: stretching or tearing of skin or soft tissues (muscles, ligaments,
tendons, etc.) that surround the hip joint, a more limited surgical field which may cause
the surgery to last longer, potential nerve injury/damage, fracturing of bones when the
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new implants are being inserted, and limitations when it comes to choosing possible hip
joint implants.
In conclusion, based on recent research, smaller incisions have not been prove to
have any sort of substantial benefits aside from the fact that they “look better” following
surgery.
Complications During/Following Surgery
Some believe that minimally invasive surgery should be simpler and easier with
fewer problems both during surgery and after surgery. A smaller incision should result in
less blood that is lost during surgery and less damage to the tissues around the hip joint.
The surgery should be a lot faster, and you shouldn’t have to worry about any problems
down the road with your new hip replacement…right? Recent research has investigated
these areas of hip replacement surgery when comparing the minimally invasive and
traditional approaches. Their findings may surprise you.
Studies by Woolson et al (2004) and Goldstein et al (2005) have shown some
evidence of increased death of tissue surrounding the hip joint and/or poor wound healing
after mini-incision surgeries. These studies further emphasize the fact that there is more
trauma to the underlying tissue during these surgeries due to the fact that surgeons must
provide a great deal of retraction (“pulling apart”) to the surgical site in order to expose
the area that they are working on. Although the muscles that surround the hip joint may
not be traumatized as much during minimally invasive surgery, more forceful retraction
leads to further damage to the underlying tissue. Figure II illustrates retraction being
performed during minimally invasive total hip surgery.
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Figure II: Retraction performed during minimally invasive total hip surgery
Source: Smith & Nephew “Minimally Invasive Hip Replacement Through the Posterior Approach”
http://www.mihip.com/surgeon_stepbystep19.html
Furthermore, minimally invasive surgery has also been shown to result in longer
surgical time (due to the complexity of the surgery), increased complication rates from
fractures or damage to surrounding nerves (due to decreased exposure of the area), and a
greater risk of incorrect positioning of the replacement components (Woolson 2005).
These aforementioned studies highlighted the greater risk of complications during
surgery; however, post-operative complications have also been investigated.
A study conducted by Oganda and his colleagues showed no significant
difference between the two surgical approaches in terms of blood loss during surgery,
blood transfusions needed following surgery, pain scores as reported by the patients
following surgery, or use of pain relieving medications between the two groups following
surgery. They also found no difference in early ability to walk after surgery, and length
of hospital stays were not significantly different among the two groups in their study
(Ogonda 2005).
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Some additional complications following hip replacement surgery may include
fractures, dislocations, and infections. A study that was conducted involving patients
who underwent two-incision minimally invasive surgery showed that 10 percent of those
who participated had to undergo an early reoperation to treat either a fracture of the
femur, a dislocation, or an infection (Sculco 2005). According to Gizelle Dean DPT, a
treating clinician and professor at Penn State Shenango, long-term complications based
on the literature include failure of the fixation (artificial components), dislocation (4% or
less), infection (0.5%), and revision rate of 18%-20% (meaning that 18%-20% of patients
who underwent the surgery had to go back in to have their initial surgery fixed) (Personal
Communication March 22, 2008).
In conclusion, minimally invasive surgery was believed to result in fewer
complications both during and after surgery; however, recent research does not
completely support this claim. There are no long term studies that support the idea that
minimally invasive surgery produces fewer complications during/after surgery as
compared to the more traditional approach.
Recovery Time
One of your main goals following surgery is to return to your normal daily
activities with minimal to no pain and no decrease in functioning. Recovery time is
another important component when deciding on a surgery approach: will one approach
help to “speed up” the recovery process more so than another?
According to Gizelle Dean DPT, quicker return to functioning is definitely
apparent with the minimally invasive total hip surgery (based on her limited clinical
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experiences treating patients who have had the procedure). She has only treated one
patient who has elected to have the minimally invasive procedure. The woman had one
hip replaced, returned home in 2-3 days, and completed approximately 1 month of
physical therapy at her own request (the doctor who performed her surgery did not feel
that physical therapy was needed). When the woman entered physical therapy, she had
decreased range of motion of the hip, decreased strength, poor balance with a history of
balance problems, and decreased overall function. She lived alone with her dog and had
no family alive to help her. One year later, the same patient had her other hip replaced
using the same minimally invasive approach. She entered physical therapy for the second
time with the same deficits that she had encountered after the first surgery, and her home
situation was the same as with the first procedure. The patient did experience more pain
and some additional complications with the second procedure (could have been due to
other compounding factors such as age, declining overall health, other medical
complications, etc.) (Personal Communication March 22, 2008).
Concluding, minimally invasive surgery has been shown to improve recovery
time in some cases; however, as Dr. Dean stated, “The bottom line is that long-term
outcomes are unknown” (Personal Communication March 22, 2008).
Limitations
As with any surgical procedure, minimally invasive surgery has limitations.
When looking at the surgery itself, special tools and instruments are required. Also, not
every surgeon can perform the minimally invasive surgery; special skill and training is
required. Furthermore, not every patient is eligible (or able) to receive minimally
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invasive surgery. When looking at new surgical approaches, do the limitations outweigh
the gains?
Specially designed tools and instruments are required to successfully complete the
surgery due to the fact that the surgeon is working in such a small visual field as a result
of the mini-incision(s). Some surgeons use special surgical instruments to help increase
the visualization of the hip joint; additionally, computers may be used as sort of
“navigation devices” to help guide the joint replacement into its correct position
(Minimally Invasive Hip 2008). Furthermore, a study conducted by R. Berger showed
that while the minimally invasive technique “shows great promise”, the surgical
technique is rather meticulous and requires special instruction and specialized surgical
instrumentation (Berger 2006).
1.Handle 2.Screw mechanism 3.Parallel guide tunnels 4.Guide sleeves to take various diameter wires 5.
Femoral neck footplate with long horizontal rod 6. Femoral footplate with spikes 7.Srewdriver
8.Repositioning jig
Figure III: Examples of instruments used during minimally invasive hip surgery
Source: www.minimalinvasivehip.com
As mentioned earlier, not every surgeon is able to perform the minimally invasive
surgery. Surgeons must complete special training through the Zimmer Institute in order
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to be able to perform the minimally invasive 2-incision hip replacement procedure
(Minimally Invasive 2-Incision 2006). The number of surgeons able to complete this
particular procedure is rather scarce due to the specialized training; this may make it
more difficult when you are trying to choose a surgeon, location, etc. for surgery.
Finally, not every patient is able to undergo minimally invasive surgery. If you
are overweight, very muscular, have recently had a blood clot, are taking an unstable
medication that may increase your risk for complications, or if you have already had hip
replacement surgery on the same hip, you may not be a candidate for minimally invasive
surgery (Minimally Invasive 2-Incision 2006). Ideal patients for minimally invasive
surgery are described as “young, thin, healthy and motivated” (Minimally Invasive and
Small Incision 2005); however, people do not opt for hip replacements because they are
young and healthy. They decide on joint replacement surgery due to degeneration,
weight problems, age-related problems, or some other complicating health problems. It
is best to consult your doctor to see if you are an eligible candidate for minimally
invasive surgery.
In conclusion, minimally invasive surgery may provide advantages to some
people; however, this technique is not for everyone. Not only are there limitations during
surgery (special instrumentation and special surgical training required), but the patient
population eligible to receive the surgery is limited as well.
Conclusion
It is extremely important for you to be well informed and aware of the many
options that are available to you as a patient considering hip replacement surgery. A
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great deal of research is being performed in this area of study; however, the bottom line
remains that no long term studies have been completed to produce any significant or
substantial results in favor of minimally invasive surgery over traditional joint
replacement surgery. Based on our review of the current research, we do not feel that it
has been proven that minimally invasive total hip surgery is superior to traditional total
hip surgery. Research is constantly changing and new discoveries are being made in the
healthcare field daily; therefore, we encourage you to follow the research and ask as
many questions as you can in terms of your own care and well being when it comes to
joint replacement surgery.
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References
Berger, R.A. Minimally Invasive Total Hip Arthroplasty With Two Incisions. Operative
Techniques in Orthopaedics. Volume 16, Issue 2. April 2006 pp 102-111.
de Beer, J. MD, Petruccelli, D. MLIS, Zalzal, P. MASc MD, Winemaker, M.J. MD. Singleincision, minimally invasive total hip arthroplasty. Length doesn’t matter. The
Journal of Arthroplasty. Volume 19, Issue 8. December 2004, pp. 945-950.
Goldstein, WM, Ali R, Murphy, SI, et al: Patient priorities and importance of cosmesis after
THA: Standard versus minimal incision. Proceedings of AAOS Annual Meeting,
Washington, D.C., 2005.
Hip Replacement. National Institute of Arthritis and Musculoskeletal and Skin Diseases
(NIAMS). April 2006. Accessed 12 March 2008. www.niams.nih.gov/Health_Info/.
Hip replacement: Relieve pain, improve mobility. www.mayoclinic.com.
Minimally Invasive 2-Incision Hip Replacement Surgery FAQ. Alliance Community
Hospital. Copyright ©2006 Alliance Community Hospital.
Minimally Invasive and Small Incision Joint Replacement Surgery: What Patients Should
Consider. American Association of Hip and Knee Surgeons. June 2005.
www.aahks.org.
Minimally Invasive Hip and Knee Arthroplasty. Blue Cross & Blue Shield of Rhode Island.
Medical Coverage Policies. Copyright ©2008 Blue Cross & Blue Shield of Rhode
Island. www.bcbsri.com/.
Minimally Invasive Total Hip Replacement. American Academy of Orthopaedic Surgeons
2007. Retrieved 12 March 2008 http://orthoinfo.aaos.org/.
Ogonda et al. A minimal-incision technique in total hip arthroplasty does not improve early
postoperative outcomes- A prospective, randomized, controlled trial. J Bone Joint
Surg- amer Vol, 2005; 87A (4): 701-710.
Woolson, S.T. Small incision THR not “minimally invasive”. AAOS Bulletin. August
2005. www2.aaos.org/.
Woolson, ST, Mow CS, Syquia JF, et al: Comparison of primary total hip replacements
performed with a standard incision or a mini-incision. J Bone Joint Surg. 86A: 1353-1358,
2004.
Wright, J.M. MD, Crockett, H.C. MD, Delgado, S. SA-C, Lyman, S. PhD, Madsen, M. MD,
Sculco, T.P. MD. Mini-incision for total hip arthroplasty. A prospective, controlled
investigation with 5-year follow-up evaluation. The Journal of Arthroplasty.
Volume 19, Issue 5. August 2004, pp. 538-545.