Presentation on whether precautions, assistive devices and femoral head sizes play a role in reducing dislocation rates after a total hip arthroplasty.

1. DO PRECAUTIONS, ASSISTIVE DEVICES AND
FEMORAL HEAD SIZES PLAY A ROLE IN
REDUCING DISLOCATION RATES AFTER A
TOTAL HIP ARTHROPLASTY.
BY RICHARD NUTTALL

2. WHY I SELECTED THIS TOPIC
• My career aspiration is to be a physiotherapist.
• I currently work as a part time physiotherapist assistant at
a local hospital in Stockport.
• I mainly work on the orthopaedic department dealing with
patients who have recently had total hip and knee
replacements.
• I work with many types of health professions ranging from
occupational therapists to nurses and doctors.
• Therefore, the topic I chose is relevant to my part time job
and I hope it can help me to improve my understanding
and help me to become a better physiotherapist in the
future.

3. OSTEOARTHRITIS
• Is a degenerative joint disease, resulting from breakdown
of joint cartilage and underlying bone.
• The most common symptoms are joint pain and stiffness.
• It's the most common type of arthritis affecting both males
and females, usually in people aged 60 years old and
above.
• Affects around 8 million people in the UK.
• Osteoarthritis in the hip is the second most commonly
affect joint.

4. TOTAL HIP ARTHROPLASTY (THA)
• Is the treatment of choice for patients with an impaired
quality of life due to severe hip arthritis.
• In the UK in 2017, there were 890,681 THA's.
• Leads to rapid pain relief and restoration of function of the
hip.
• Dislocation is the main complication of this operation and
usually occurs in 2-4% of patients.
• The risk of dislocation is usually higher in the first months
after surgery.
• Therefore, certain precautions and techniques have been
applied in order to reduce the risk of a dislocation.

5. HIP PRECAUTIONS
• The precautions are suggested by the surgeon and
physiotherapist to protect the new joint and decrease the risk
of dislocation.
• Do not:
• Rotate internally or externally
• Allow Hip flexion greater than 90 degrees
• Allow adduction of the operated leg
• Cross legs
• Bend past 90 degrees
• Twist or turn

6. HIP PRECAUTIONS STUDY
• Many Hospitals have discontinued the precautions due to
unchanged dislocation rates.
Table 1 shows the difference in dislocation rates between hip precautions and no hip
precautions between different studies.

7. ASSISTIVE DEVICES
• In order to ensure that the patient follows these
precautions, the occupational therapist will assign certain
equipment to the patient to help them with day to day
tasks. These are:
• a raised toilet seat
• perching stools
• chair/bed raisers
• dressing aids
• long handled reacher.

8. ASSISTIVE DEVICES STUDY
• One study (Peak, et al., 2005) found that the additional
expenditure of the assistive devices was approximately
$655 per patient.
• The actual study found that the removal of these devices
along with the precautions, did not increase the
prevalence of a dislocation.
• It in fact promoted lower costs.
• It was associated with a higher level of patient satisfaction
as the patients achieved a faster return to daily functions
in the early postoperative period.

9. FEMORAL HEAD SIZE
• In the past smaller diameters of the femoral head have
been used when undergoing a total hip arthroplasty
• This is done in order to reduce the debris particles caused
by polyethylene
• Which in turn, reduces the risk of osteolysis as there is
less contact between the bearing surfaces (Clarke,
Gustafson, Jung, & Fujisawa, 1996).
• However, in recent times, larger femoral head sizes have
been used
• This is because of the new materials found such as cross-
linked polyethylene and hard bearings (Kluess, Martin,
Mittelmeier, Schmitz, & Bader, 2007).
• Which decrease the impact of the wear particles which
lead to toxicity.

10. FEMORAL HEAD SIZE STUDY
Study Dislocation rates (n/total (%))
28 mm diameter femoral head size 36 mm diameter femoral head size
(Howie, Holubowycz, & Middleton,
2012)
17/316 = 5.4% 4/299 = 1.3%
(Bistolfi, et al., 2011) 6/198 = 3% 1/259 = 0.4%
Table 2 shows the difference in dislocation rates between 28 mm and 36 mm femoral head size.

11. CONCLUSION
• From the data, Hip precautions and assistive devices do
not reduce the risk of a dislocation.
• However, a study suggested that a sample size of
approximately 4,000 Total Hip Arthroplasties would be
required for a randomised controlled trial to determine
whether dislocation rates differ between precaution and
non precaution groups.
• Although, a larger femoral head size decreases the risk of
a dislocation when comparing 36 mm with 28 mm.

12. REFERENCES
• Bistolfi, A., Crova, M., Rosso, F., Titolo, P., Ventura, S., & Massazza, G.
(2011). Dislocation Rate after Hip Arthroplasty within the First
Postoperative Year: 36Mm versus 28Mm Femoral Heads. HIP
International, 21(5), 559-564.
• Clarke, I., Gustafson, A., Jung, H., & Fujisawa, A. (1996). Hip-simulator
ranking of polyethylene wear:Comparisons between ceramic heads of
different sizes. Acta Orthopaedica Scandinavica, 67(2), 128-132.
• Howie, D., Holubowycz, O., & Middleton, R. (2012). Large Femoral Heads
Decrease he Incidence of Dislocation After Total Hip Arthroplasty. The
Journal of Bone and Joint Surgery-American Volume, 94(12), 1095-1102.
• Kluess, D., Martin, H., Mittelmeier, W., Schmitz, K.-P., & Bader, R. (2007).
Influence of femoral head size on impingement, dislocation and stress
distribution in total hip replacement. Medical Engineering & Physics,
29(4), 465-471..
• Peak, E., Parvizi, J., Ciminiello, M., Purtill, J., Sharkey, P., Hozack, W., &
Rothman, R. (2005). The Role of Patient Restrictions in Reducing the
Prevalence of Early Dislocation Following Total Hip Arthroplasty. The
Journal of Bone & Joint Surgery, 87(2), 247-253.