Different Approaches to Total Hip Replacement Surgery

(www.dreamstime.com, free stock photos)14

Imagine for a moment that you are the “typical” hip replacement patient:  

you are 65 years old and your right hip has been increasingly painful for the last 4 years during most of the activities that you enjoy: playing tennis with your husband, walking in the neighborhood with your best friend Jan, and taking your dog Rover to the park on the weekends. You have held out on having surgery until now, but you are in enough pain that surgery seems like an attractive option, so you decide you will see an orthopedic surgeon about the possibility of a total hip replacement (also called “total hip arthroplasty” (THA). You may think that this is the biggest decision: to have the surgery or not have the surgery, but have you considered all of the other small decisions that may go into this process?

Recently, I have had the opportunity to work as a student physical therapist in the orthopedics department at a hospital that performs many THA surgeries. I have been fortunate to not only see patients after their THA surgeries (for physical therapy evaluations and treatments), but also to observe THA surgery being performed first hand in the operating room. I have also had discussions with doctors, physical therapists (PTs), and nurses about different aspects of this surgery and the outcomes following THA procedures. I’d like to share what I have learned about this procedure from my observations and research on the topic.

THA surgery is one of the most commonly performed orthopedic surgeries: over 1 million of these surgeries are performed annually! THA patients generally have positive outcomes: the majority of patients report reduced pain, improved function and improved quality of life after the surgery and prosthetics often last 10-25 years (95% survivorship at 10 years and 80% survivorship at 25 years.1, 10, 13 Overall, THA is a very popular surgery and with an aging population, we will likely see the number of people electing to have this surgery continue to grow.

However, there is not just one way that THA surgery is performed. There are options and choices to be made such as:

Patient pre-screening, surgeon choice, use of robotic assistance, prosthetic components/joint cement, incision approach, length of incision, acetabular “cup” orientation, type of anesthesia, hospital stay/in patient physical therapy, reducing post-operative complications, out patient physical therapy…

There are an exhausting number of iterations and variations on how this surgery is performed. Many of which are discussed with your surgeon before surgery and some of which are left up to your preference. Regardless of what you and your surgeon choose to do, I think that knowledge of what options are out there and some of the pros and cons of each can be helpful as you are facing a potential surgery. Feel free to skip to the sections that interest you the most.

From the literature that I’ve read and my observations of THA surgery and the early rehabilitation process (first few days after surgery/inpatient hospital rehabilitation), here are my findings:

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  • Patient Pre-screening (and associated prognosis):

    (Some surgeons screen heavily before performing surgery and may refuse to perform THA if a patient has certain characteristics that may predispose a poor outcome)

Research Literature Says:

A recent systematic review (2016)1 found strong evidence for associations between functional outcomes* after THA surgery and these factors:

high BMI (> 28 to > 35 kg/m2) (worse outcomes), older age (> 60 to > 75 years old) (worse outcomes/increased risk of complications5), higher pre-operative level of function (better outcomes), more/worse comorbidities (worse outcomes), better mental health (better short-term outcomes)

Variables that didn’t seem to predict functional outcome (or had weak evidence as predictors) after THA surgery1 were:

-gender**, socioeconomic status, quadriceps muscle strength, alcohol consumption

*Note: a limitation of this review was that they did not look at pain as an outcome

**Some studies report gender differences with males having better outcomes compared with females after THA8

Clinical Experience Says:

Some doctors “screen” patients heavily before agreeing to perform THA surgery. Certain traits that may disqualify a potential THA patient are:

high BMI, current nicotine use/smoking, IV drug use, poor likelihood of compliance with precautions, physical therapy, or lifestyle changes (i.e., diet and exercise), high risk of fracture (e.g., severely osteoporotic), no prior attempt at conservative treatments (e.g., physical therapy, injections, analgesic medications, activity modifications).

Surgeons are rigorous not only to ensure positive functional outcomes after THA surgery but also to prevent infection of the prosthesis and certain risk factors predisposing infection are taken very seriously (in some cases disqualifying patients from THA surgery if they are at a high risk for infection). If a prosthetic becomes infected it must be removed.

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  • Surgeon Choice:

    (Orthopedic specialist vs. orthopedic generalist, large teaching hospital vs. small rural hospital etc)

This is a whole topic in itself…see my other blog post HERE

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  • Use of Robotic Assistance:

    (‘Manual’ surgery = no robotic component vs. ‘robot-assisted’ surgery)

Research Literature Says:

Robotic assistance in some cases improves accurate acetabular cup placement and could reduce leg length discrepancy following THA surgery7, 10, 13  But, robotic assistance is also associated with longer surgery times and higher cost.13 It is unclear whether these differences translate into differences in functional outcomes for patients.

Clinical Experience Says:

Some surgeons perform one type of operation specifically and some perform both “manual” operations (no robotic assistance) and robot assisted surgeries and will discuss pros and cons with patients prior to choosing to use robotic assistance.

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  • Prosthetic Components/Joint “Cement”: 

    (What materials are used for your “new hip,” titanium, ceramic, polyethylene variations etc.)

Research Literature Says:

Much of the literature on materials properties of prosthetics is over my head (prosthetics can be made out of metal, ceramic, polyethylene, etc.), but I do find the literature/clinical decision making on use of bone cement (polymethylmethacrylate) interesting. Cement is sometimes used to improve fit of the prosthetic to bone interface. As one author explains, “Cement is a grout not a glue: fixation is achieved by mechanical interlock rather than adhesion” but, cement does not always produce the best fit and the cement “debris” can cause inflammation in some cases.10

Non-cemented implants may have less stable short-term fixation as the bone is allowed to grow into the porous synthetic prosthetic. However, the prosthetic is not merely placed, but is “press-fit” into place so that it won’t move prior to the new bone growth into the prosthetic (screws or pegs can also be placed to help with fixation). These techniques in which cement is not used are known as “biological fixation”).5

Clinical Experience Says:

Some surgeons prefer non-cemented prosthetics and may allow weight bearing as tolerated (WBAT) for patients immediately post operatively, due to the stability provided from the “press-fit” implant with or without screw fixation

Sir John Charnley is credited with refining the use of bone cement for THAs and Pillar and Galante are often credited with developing and implementing non-cemented techniques (“biological fixation”).5

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  • Incision Approach:

    (How the surgeon accesses your hip joint: posterior approach (rear/side), anterior/anterolateral approach (front), or lateral approach (side))

Research Literature Says:

Posterior Approach:

Pros: hip abductor muscles are not disrupted8

Cons: increased risk of dislocation, hip short external rotator muscles are cut8

Anterior/Anterolateral Approach:

Pros: early benefits in pain and functional ratings as well as decreased risk of dislocation and reduced post-op narcotics use 8, 9

Cons: partial detachment of gluteus medius muscle, associated abductor weakness8

Lateral Approach:

Pros: easier implant placement5 Decreased risk of dislocation8

Cons: partial detachment of gluteus medius muscle, associated abductor weakness5  Risk of heterotopic ossification8

One systematic review & meta-analysis proposes no clear advantages to anterior vs. posterior approach.9 The authors recommend further research before firmly recommending either approach, stating “until further research is available, we recommend that the approach for THA be based on patient characteristics, surgeon experience and surgeon and patient preference.” 9

However, approach and associated differences in muscle damage do not necessarily correlate with functional outcomes (i.e., there were no differences in functional outcomes for anterior vs. lateral approaches for THA in one study. 2

Clinical Experience Says:

Traditional thinking is that the anterior approach has less risk of dislocation, but it may be more difficult surgically and thus may have longer operating time and blood loss, with associated increased risk for complications. The posterior approach benefits from not compromising the gluteus medius muscle. 5, 8 For choice of approach used in THA, much depends on surgeon training and preference.

Most of the patients that we saw had had a posterior approach THA. This is consistent with the literature reporting the posterior approach as the most widely performed approach.5

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  • Length of Incision:

    (‘Traditional’ THA = longer incision vs. ‘minimally invasive’ THA = smaller incision)

Research Literature Says:

Minimally invasive approaches theoretically injure less tissue with smaller incisions, but may be hampered by increased operative time, greater risk of malaligned components, increased blood loss and complications, and increased cost. 8, 13

Clinical Experience Says:

To my knowledge, the surgeons who we saw patients from did not use minimally invasive techniques, but preferred a traditional incision with good reported outcomes.

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  • Acetabular “Cup” Orientation:

    (What angle the “cup” of the hip joint is set at)

Research Literature Says:

“Lewinnek’s safe zone”:

(Most widely accepted target acetabular orientation): 7, 11

5-25° anteversion & 30-40° inclination

Revised Standards (based on a 2017 case control study of THA dislocations):

Cup orientation goals: optomize biomechanics and reduce risk of dislocation: 11

15-30° anteversion & 40-50° inclination

Anteversion = measure of how far forward the cup faces

Inclination (aka abduction) = measure of how far up from the ground the cup faces

Clinical Experience Says:

The doctors and nurses I spoke with indicated their target acetabular orientation to be:

20° anteversion & 40° inclination

(of note, this range is very near the proposed range for “surgical” reference frame* for cup orientation from one review: 11

17-18° anteversion and 40° inclination)

*Different reference frames have been used to define cup orientation (surgical, anatomic, and radiographic)

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  • Type of Anesthesia:

    (“General” anesthesia vs. “regional block” or “spinal” anesthesia)

Research Literature Says:

Regional anesthesia via injected anesthetic agents near the spinal cord (“spinal block”) tend to have lower risk of readmission and complications compared to general anesthetic. 13

Spinal anesthesia can reduce analgesic drug use and post-operative pain immediately following surgery. 13

Clinical Experience Says:

Anecdotally, patients with general anesthesia are more likely to experience nausea and vomiting after surgery. Theoretically, this could increase hospital length of stay or slightly delay ability to progress with post-operative physical therapy. Patients with a spinal block may experience trunk instability during standing/walking immediately after surgery due to anesthetized motor nerves, which must be taken into account for physical therapy progression and safety.

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  • Hospital Length of Stay and In Patient Physical Therapy:

    (How long you will stay in the hospital after surgery and what physical therapy will consist of while you are there)

Research Literature Says:

In patient (in hospital) physical therapy (usually started within 24 hours of surgery) is focused on achieving “functional milestones” or goals that allow a patient to be safely mobile in his or her discharge destination environment (e.g., home, rehab facility, skilled nursing facility).6, 8 Interestingly, one study found significantly decreasing length of stay (LOS) for THA patients over the 1990 to 2000 decade (mean LOS in 1990 was 9.7 days, in 2000 was 5.3 days).6

Certain “Functional Milestones” for patients in the hospital include4

1-Unassisted transfer in/out of bed, 2-Unassisted walking with a walker, 3-Unassisted ascend/descend of 4 steps with railing

Patients meeting these goals and able to follow hip precautions usually are able to discharge home. Roughly 2/3 of patients are able to discharge home and 1/3 go to a rehabilitation or skilled nursing facility. 6, 8

Clinical Experience Says:

In Patient THA Goals need to address these “Functional Milestones”:

1- precautions/home exercise program education, 2-transfer training (e.g. sit to stand, bed to toilet, etc.), 3- functional bed mobility, 4-gait training with assistive device- functional gait distance (100ft), 5- stairs training

THA patients we worked with stayed in the hospital for a minimum of 1 day and most patients were discharged on post-operative day 2 (about 70% of patients), staying mostly a maximum of 3 days unless awaiting precertification (insurance approval) for a rehabilitation facility.

Note: patients have better coping strategies after THA if they receive education before surgery to help them understand the clinical course of recovery including post-operative functional expectations, rehabilitation exercises, and discharge planning. 8

At the hospital that I worked at, patients were encouraged to attend a free “Joint Camp” before surgery that served this educational purpose. Patients who had attended “Joint Camp” were generally well prepared and had more accurate expectations following surgery and were eager to work with physical therapists compared with those who did not attend “Joint Camp” (again, my anecdotal observation).

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  • Reducing Post-Operative Complications:

    (Surgical complications can include pain management, blood loss, risk of dislocation or fracture, risk of infection or blood clots, etc.)

Research Literature Says:

Complications to avoid/manage include: Blood loss, pain control, risk of dislocation or fracture, risk of infection, risk of blood clot/DVT, nerve injury etc. Doctors, nurses, physical therapists work as a team to prevent complications with education, early mobility/exercises and functional training as well as pharmacological interventions.8

Clinical Experience Says:

Follow your precautions! (reduces risk of dislocation and promotes proper tissue healing)

Hip precautions are usually in place for 4-6 weeks post operatively, but time length can vary depending on surgeon preference.

Check with your surgeon for recommendations on precautions specific to your surgery (including weight bearing status and motions to avoid).

Examples of common precautions by approach include:

Posterior approach precautions: No flexion > 90° (bending hip up greater than 90°), No adduction  (crossing legs), No internal rotation (turning hip inward, “pigeon toes”)

Anterior approach precautions

No excessive extension (don’t let your leg get too far behind your body, some say no more than you would with a normal walking step with the opposite leg, some say not past neutral or leg in line with body), No crossing your legs, No external rotation past neutral (turning hip out, “toes rolling out”)

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  • Out Patient Physical Therapy:

    (What exercises/activities to include in your rehabilitation program once you are out of the hospital)

Research Literature Says:

Early Rehabilitation (0-8wks after surgery)

Two systematic reviews on rehabilitation exercise after THA  report, that there is no conclusive research for which specific exercises to include in strengthening protocols following THA (though the authors note it is important to strengthen hip abductors, hip and knee extensors and flexor muscles). 3, 4

In early THA rehab (<8wks): body weight supported treadmill training and cycle ergometry are successful in improving function.  Early mobilization is important as is early strength training of the quadriceps muscle on the operative limb. 3, 4

Stepping exercises incorporated into usual physical therapy following THA can increase hip abductor and knee extensor strength compared with usual physical therapy. 12

Later Rehabilitation (> 8wks after surgery)

Later exercises included in THA rehabilitation programs may include bridges, resisted external rotation and abduction exercises, squats, lunges, step ups, and leg press. 8 In later THA rehabilitation, (>8wks) weight bearing exercises and eccentric exercises for hip abductor muscles are important to include in a comprehensive lower extremity strength program.. 3,4

Clinical Experience Says:

Early Rehabilitation

Early physical therapy emphasizes ankle active range of motion (AROM) and active assisted range of motion (AAROM) on the operative hip and knee in supine within hip precautions as well as functional mobility and gait and stairs training with an assistive device. Exercises may include:8 ankle pumps, quad and glute isometrics, heel slides to 90°, short arc quads, hip abduction and adduction to neutral/anatomic position.

Physical therapy sessions with most THA patients that I worked with in the hospital setting included some variation of the above exercises as well as training for bed mobility and transfers, gait, stairs, and assistive device use.

Later Rehabilitation

Patients do not usually require extensive out patient physical therapy and depending on ability and motivation may do a lot of their rehabilitation as a prescribed home exercise program. Most strength and range of motion impairments for these individuals are adequately addressed in early rehabilitation and consistent daily mobility and exercise that individuals can perform on their own including activities of daily living, walking, swimming, or biking programs, and for some individuals getting back to higher level activities such as tennis, golf, or dancing (most patients take 3-6 months to return to sports after THA). 8

*Frequency of PT sessions 1x/day vs. 2x/day while in the hospital does not seem to impact hospital length of stay or functional outcomes. Though one study found a trend for 2x/day being better, this difference was not significant nor did it seem to be clinically meaningful. 3 However, there may be other reasons for conducting PT sessions 2x/day; for example patient satisfaction ratings, reduced fall risk, and better adherence to home exercise programs following discharge (all speculative benefits).

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References:

  1. Buirs LD, Van Beers LWAH, Scholtes VAB, Pastoors T, Sprague S, Poolman RW. Predictors of physical functioning after total hip arthroplasty: a systematic review. BMJ Open. 2016;6(9).
  2. De Anta-Díaz B, Serralta-Gomis J, Lizaur-Utrilla A, Benavidez E, López-Prats FA. No differences between direct anterior and lateral approach for primary total hip arthroplasty related to muscle damage or functional outcome. International Orthopaedics. 2016;40(10):2025-2030
  3. DiMonico, M, & Castiglioni, C. Which type of exercise therapy is effective after hip arthroplasty? A systematic review of randomized controlled trials. European Journal of Physical and Rehabilitation Medicine. 2013; 49: 893-907.
  4. DiMonico, M, Vallero, F, Tappero, R, Cavanna A. Rehabilitation after total hip arthroplasty: a systematic review of controlled trials on physical exercise programs. European Journal of Physical and Rehabilitation Medicine. 2009; 45 (3):303-317
  5. Galia CR, Diesel CV, Guimarães MR, Ribeiro TA. Total hip arthroplasty: a still evolving technique. Revista Brasileira de Ortopedia (English Edition). 2017;52(5):521-527.
  6. Ganz S., Wilson P., Cioppa-Mosca J, Peterson MG. The day of discharge after total hip arthroplasty and the achievement of rehabilitation functional milestones. The Journal of Arthroplasty. 2003;18(4):453-457.
  7. Harrison CL, Thomson AI, Cutts S, Rowe PJ, Riches PE. Research Synthesis of Recommended Acetabular Cup Orientations for Total Hip Arthroplasty. The Journal of Arthroplasty. 2014;29(2):377-382.
  8. Heislein, D. Total Hip Arthroplasty (THA). PTNow. http://www.ptnow.org/clinical-summaries-detail/total-hip-arthroplasty-tha. June 14th, 2016. Accessed December 28th, 2017.
  9. Higgins BT, Barlow DR, Heagerty NE, Lin TJ. Anterior vs. Posterior Approach for Total Hip Arthroplasty, a Systematic Review and Meta-analysis. The Journal of Arthroplasty. 2015;30(3):419-434.
  10. Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip replacement. The Lancet. 2007;370(9597):1508–1519.
  11. Reina N, Putman S, Desmarchelier R, et al. Can a target zone safer than Lewinnek’s safe zone be defined to prevent instability of total hip arthroplasties? Case-control study of 56 dislocated THA and 93 matched controls. Orthopaedics & Traumatology: Surgery & Research. 2017;103(5):657-661.
  12. Tsukagoshi R, Tateuchi H, Fukumoto Y, Okumura H, Ichihashi N. Stepping Exercises Improve Muscle Strength in the Early Postoperative Phase After Total Hip Arthroplasty: A Retrospective Study. American Journal of Physical Medicine & Rehabilitation. 2012;91(1):43-52.
  13. Zagra L. Advances in hip arthroplasty surgery: what is justified? EFORT Open Reviews. 2017;2 (5):171-178.
  14. https://www.dreamstime.com/royalty-free-stock-photos-total-hip-replacement-surgery-image23250668

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