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AClffE CARE HANDBOOK FOR PHYSICAL THERAPISTS

Figure 3-13. Bilateral total h;p arthroplasty.

components has the advantage of biological fixation, reducing the

incidence of aseptic loosellillg (the loosening caused by wear debris

from the components). With uncemented components, weight bearing

can be limited by surgeon protocol, but weight bearing should not be

discouraged.38 Weight bearing promotes bony ingrowth with the

uncemented prosthetic components by allowing physiologic strain in

the bone, thus increasing the activity of remodeling. With uncemented

THA, the emphasis for the patient should be the prevention of torque

or twisting on the operated leg while weight bearing.

The use of a cemented prosthesis (usually the femoral component)

is reserved for an individual with a decreased ability to regenerate

bone, such as a patient with osteopenia or osteoporosis.J9 A cemented

prosthesis allows fot full weight bearing early in the recovery phase.

A bipolar prosthesis consists of a metallic acetabular cup and polyethylene liner with a snap-fit socket placed over a femoral prosthesis, as shown in Figure 3_14.40 A bipolar prosthesis is a type of hip

arthroplasty used for revision when there is instability caused by

osseous or muscular insufficiency that makes a patient's hip morc

likely to dislocate.

Surgical approaches and movement precaurions for THA are presented in Table 3_64'.42 A good understanding of the surgical approach taken to expose the hip joint is necessary to determine

movement precautions that prevent dislocation postoperatively. In the

acute care setting, the risk of dislocation is significant because of the

.\tUSCULOSKEU:,IAL SYSTEM

193

Figure 3-14. Mcuhfied bIpolar CliP. Polyetbylene CLIP IS placed over bead, and

the" the metal cup IS pressed over It. polyetbylene Imer is locked m metallic

cup, and bead is locked In socket of polyethylene liner. EntIre cup moves lvith

femoral head as olle lIlIIt, so cup canllot assume valglls or varus fixed positiol1. Metal bead ca" rotate HI plastIC socket m aXIS of neck. CliP mllst be used witb the femoral prostheSIS designed to fit properly mto plastic liner. (Wllh

permisS/oll (rom JIV Harkess. Arthroplasty o( Hip. In AH Crenshaw [edj,

Cmllpbd/'s OperatIve OrthopaedIcs, Vol. 1 [8th edj. St. LOllis: Mosby, 1998.)

Table 3-6. Surgical Approaches and Precaurions for Toral Hip Anhroplasry"

Surgical

Approach

Precnutions

Posterolateral

No hip flexion beyond 90 degrees

(most common)

No excessive internal rotation

No hip adduction past neutral

Lnteral

No combined hip flexion beyond 90 degrees with

ndduccion, internal rmation, or bmh

AnterolMeral

Hip extension and external rotation are to be avoided

·Hlp !ourgcry performcd in conJunction with a trochanteric ostcotomy (removal and

rc.machmcOi of the gre.1tcr trochanter) will require an additional movcment restriction

of no active abduction or pa!osive adduction. Weight bearing of the surgical limb may be

limned further.