Total Hip Replacements: Posterior versus Anterior Approach

Total hip replacements or arthroplasties (THA) are one of the most commonly performed joint replacement surgeries.  With wear and tear, broken bones, and various problems with blood supply that can occur at the hip, there will always be a need for some type of procedure like this.  The components involved and surgical approach for the replacement may vary, though, based on an individual’s age, past history, and desired activity level.

There is more than one way to perform a THA, but the overarching mechanics are the same.  Just like the shoulder, the hip joint is a ball-and-socket joint; thus, the prosthetic (artificial) portion of the hip joint consists of two parts: a cup-like component that is attached to the acetabulum (a portion of the pelvic bone) to make a socket, and a shaft with a round top that attaches to the femur (long bone of the leg) to make up the ball.  The damaged parts of the hip bone are removed and replaced with the prosthetic components.  There are several different types of materials that can be used for the hip prosthetic.  These material combinations can include metal-on-polyethylene, metal-on-metal, and ceramic-on-ceramic.  Each material combination has both pros and cons so it is important to discuss the best type of replacement for your intended level of activity.  The same is true for the attachment of the prosthetic.  There is an option of cementing the replacement parts to the bone or doing what is called a press fit which allows bone to grow into the prosthetic to hold it securely in place.  Determining which technique to use will depend on several factors including bone quality and strength.

In addition to the different types of material and attachment techniques that can be used for the hip joint prosthetic, the type of surgical approach used is also important to understand.  The most popular approach is known as the posterior approachDuring this surgery a curved incision is made along the posterior (back) hip which wraps down and to the side of the hip. The incision used is approximately 10 to 12 inches long.  Muscles and soft tissue that typically keep the hip stable are then cut, including the fascia lata, gluteus maximus, and several external rotator muscles of the hip.  The hip is dislocated, the arthritic surfaces of the bone are removed, the prosthetic pieces are attached, the hip is relocated in the socket, muscle and soft tissue that were previously cut are reattached, and the incision is closed.

The anterior approach is a different method of hip replacement which is not used as frequently as the posterior approach.  During this procedure an incision is made on the anterior (front) side of the hip instead of the posterior side.  The surgeon works between the muscles without detaching them from the bone when they replace the arthritic surfaces, thus less muscle damage occurs.  Along with the increased difficulty in performing this approach for a THA, the anterior approach requires a special table to be used in order to perform the procedure.  This may account for some of why the procedure is not used as often as the posterior approach.

So what are the pros and cons for having a posterior or anterior hip replacement?  Posterior hip replacements:

  • Pros
    • Provide the best view of the hip
    • Less likely to cause nerve damage
    • Cons
      • Must maintain strict hip precautions to prevent dislocation
      • Greater risk of dislocation (due to stabilization muscles being cut and then reattached)
      • Cutting of major muscles which require reattachment

Anterior hip replacement

  • Pros
    • Less damage to muscles
    • Less post-operative pain (due to less muscle damage)
    • Faster recovery than traditional posterior approach
    • Decreased risk of dislocation (due to muscles that stabilize hip not being cut)
    • Better range of motion (due to lack of strict hip precautions limiting motion)
    • Shorter hospital stay (but can vary based on patient and frequency of therapy in the hospital)
    • Cons
      • Obese or very muscular patient’s may not be good candidates
      • More challenging and technical surgery than posterior approach
        • Less visibility
        • Have to work between muscles without cutting or damaging nerves
  • Potential risk for nerve damage
  • Wound healing issues with patients with a larger amount of abdominal fat

Do your research in order to help determine which method and surgeon are the best for you.  As the THA procedure has been refined over the years, its longevity has improved thus allowing it to be performed at a much younger age than in previous decades.  There is over an 80% chance for a hip replacement lasting 20 years.  Various factors can increase the chances of failure, however, including an individual’s weight being over 165 lbs as well as level of activity.  Performing strengthening exercises is good for stabilizing the hip, but excessive high impact exercises can cause too much force and can increase the likelihood of replacement failure.  Despite the recent trends, rehab is very important in order to regain your full potential and recovery.  We have treated several patients who were told that they did not need outpatient physical therapy and ended up with other complications afterward.  For more information on the importance of rehabilitation following a total joint replacement surgery, check out our past blog on the topic here.


Treatment for a Total Shoulder Replacement and a Reverse Total Shoulder Replacement

Our last 2 blogs discussed what a total shoulder replacement or arthroplasty (TSA) and reverse total shoulder arthroplasty (rTSA) are and why one might need these procedures.  Now let’s discuss how to properly rehabilitate the shoulder following these procedures.

Immediately following surgery there will be many restrictions regarding use of the shoulder and these precautions are important.  The shoulder is still in its healing stage and performing certain motions too early can disrupt the healing process or damage the repairs that the surgeon performed.  Certain aspects of rehab immediately following a TSA and rTSA are the same.  A sling is to be worn continuously for 3-4 weeks post-operatively, a towel should be placed under the elbow when lying on your back, there should be no active lifting of the arm or any objects, no bearing weight through the operated arm, and no soaking in water.  These restrictions are gradually reduced as rehab progresses.  For example, after 4-6 weeks a patient can begin lifting a coffee cup with the operated arm, but should not lift greater than 5 lbs until the surgeon permits.

Certain precautions are also exclusive to the type of replacement performed.  For a TSA, external rotation (rotating the arm outward) is to be restricted to 30 degrees of rotation initially in order to maintain the integrity of the structures in the front (anterior) of the shoulder.  This is gradually progressed throughout rehab, but precaution is still taken to avoid excessive stress even 12 weeks after surgery.  Active internal rotation (rotation inward) is avoided until 6 weeks post-op as well in order to protect the healing muscles.  With a rTSA, you should not attempt to reach behind your back following surgery because combined internal rotation and extension (backward reaching) motions could potentially dislocate the shoulder.  Activation of the deltoid muscle by lifting out to the side is to be restricted for 4 to 6 weeks in a rTSA in order for the muscle to heal properly following surgery.  Healing of this muscle is important due to the fact that the deltoid will be the muscle that primarily moves the arm following a rTSA.

Passive range of motion (PROM) is an essential component to Phase 1 of rehab for a TSA and rTSA.  For this treatment, either a therapist or a trained family member moves the arm within the available ranges, not with the goal of “stretching”.  The repeated movement assists with regaining proper motion in the shoulder without stressing the healing structures.  As passive motion is regained, active motion (patient actively moving the body part) can be restored in the elbow, wrist, and hand.  These areas can become weak due to lack of use following surgery; therefore, they will also require strengthening in the course of rehab.  The shoulder blade area is another region that should not be forgotten.  Having a stable shoulder blade is like having a good foundation on a house; without it, the shoulder will not move properly or be as stable once active movements can be performed. 

Active assistive range of motion (AAROM) will also be performed in the early stages of rehab.  These exercises involve active use of the arm while assisting with an outside source. For example, an individual can hold onto a stick with both arms and attempt to lift the stick overhead.  The operated arm ends up actively lifting while having assistance from the stick and non-operated arm.  Isometric exercises are typically utilized in phase 1 as well.  These exercises involve gentle activation of the shoulder muscles through pressure without actively lifting or moving the arm.

Phase 2 of rehab begins active range of motion (AROM) which involves actively lifting the arm without any assistance.  The weight of the arm itself serves as resistance which is why this phase is not to be started until 4-6 weeks following a TSA and 6 weeks following a rTSA.  Activation of the deltoid muscle following a rTSA will also begin at this stage.

Phase 3 in a TSA starts at 6 weeks at which point more stretching may occur as well as the beginning stages of resisted rotation exercises.  Later stages of Phase 2 in a rTSA also allows gentle resistance to be added.  Phase 4 of a TSA and Phase 3 of a rTSA are not to begin until 12 weeks following surgery and these stages are when more advanced strengthening exercises can occur via the use of weights, resistance bands, or other equipment and exercises that provides resistance to the arm.  Even after in clinic rehab is completed, an individual who has had a TSA or rTSA will still need to perform exercises in the form of a home exercise program (HEP) to further progress strength, improve function, and maintain the improvements that have already been gained.

While many restrictions are in place and rehabilitation can take was seems like a very long time, the process is important in order to prevent reinjury or damage to the various structures in the shoulder.  As discussed in our last blog, full active motion is not expected following a rTSA; however, more normalized function is expected in both a TSA and rTSA around 3-4 months following surgery and final results are expected approximately 1 year after surgery.  We hope that this blog was informative.  If you have any questions on this topic or any others in which you are interested, feel free to leave any questions, comments, or suggestions. Thank you for reading and stay active.



What is a Reverse Total Shoulder Replacement?

Our last blog discussed the purpose and benefit of a total shoulder replacement or arthroplasty (TSA).  Today’s blog will discuss what a reverse total shoulder arthroplasty (rTSA) is and why someone might need one.

Why would someone have a reverse total shoulder replacement versus a typical TSA?  This particular procedure is used for conditions including non-repairable rotator cuff damage in conjunction with arthritis, complex shoulder fractures, and revisions of failed conventional TSAs.  For more information about the anatomy and function of the rotator cuff, check out our past blog on the topic here. A traditional TSA can be very beneficial for pain related to arthritis at the shoulder; but if the rotator cuff is not functioning properly, then the traditional TSA will not be effective in restoring function to the shoulder.  The structure of a rTSA allows muscles other than those of the rotator cuff to assist with movement; therefore, it is a more viable option for individuals who have a non-functioning rotator cuff.

What is the structure of a rTSA? The normal anatomy of the shoulder is a ball and socket joint with the ball being the top of the humerus (upper arm bone) and the socket being the glenoid (cup like structure at the edge of the shoulder blade).  A rTSA reverses the ball and socket components of the shoulder anatomy.  Instead of the humerus forming the ball, an artificial metal ball is attached to the glenoid surface; and instead of the glenoid forming the socket, the head of the humerus is taken off and replaced with a plastic artificial socket.  This gives the deltoid muscle (a muscle that lays overtop of the rotator cuff) a biomechanical advantage in order to lift and move the arm.  If there is severe enough weakness in the muscles that rotate the shoulder outward (external rotators), then a surgeon may also perform a tendon transfer using the tendon from the latissimus dorsi muscle.

What can be expected from rehab following a rTSA?  The expectations for range of motion and strength are a little different between a TSA and a rTSA.  In the case of a rTSA, full motion is not expected.  Even though the deltoid muscle has the ability to lift the arm, it is not capable of producing the same range of motion as when the rotator cuff muscles are intact.  There is also the potential for external rotator weakness as previously discussed.  If a tendon transfer is not performed to correct a severe degree of external rotation weakness, then this will also limit the mobility of the arm following surgery.  Despite the limitation in full motion, satisfaction following a rTSA is typically very high.

Stay tuned for our next blog which discusses the rehab parameters for both a TSA and rTSA.  We hope that this blog was informative.  If you have any questions on this topic or any others in which you are interested, feel free to leave any questions, comments, or suggestions.



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