- See:
-
post surgery antibiotic prophylaxis
-
exam for THR loosening:
-
bone scans for THR
- Discussion:
- post op AP & lateral x-rays should include entire length of stem & cement mass;
- femur and cement column are inspected carefully and compared w/ previous films for changes
indicating component loosening, stem failure, trochanteric problems, or infection;
-
Radiographic Views:
- frog leg lateral: gives best lateral of prox portion of femoral component;
- cross table lateral:
- for evaluation of position of acetabular component (anteversion) & status of post bone stock in posterior column & neck of ilium;
- weight bearing and non wt bearing views:
- may detect implant loosening;
- push pull views: to evaluate for loosening of components;
- same as AP view of hip w/ examiner providing distraction and compression to the hip thru the femur;
- Leg Length and Offset:
- leg length descrepancy:
- measured by noting the realative positions of the lesser trochanters from a line drawn tangential to the ischium;
- as noted by Ranawat (Orthopedics 1999), 87% of patients had leg lengths within 5 mm of each other;
- note that with an increased offset femoral component, the gluteus medius may be tight which causes a pelvic tilt, and gives an
apparent leg length inequality;
- as the gluteus medius stretches out over several months, the apparent leg length inquality decreases toward normal;
- reference:
- Hip arthroplasty: postoperative management problems. The pants too short, the leg too long. C.S. Ranawat. Orthopedics. Vol 22. No 9. Sep 1999. 845.
- Clinical significance of leg length inequality after total hip arthroplasty. J. Edeen and PF Sharkey. Am J. Orthop. Vol 24. 1995. p 347.
- Functional leg length inequality following total hip arthroplasty. CS Ranawat. J. Arthroplasty. Vol 12. 1997. p 359.
-
Surgical Treatment of Limb-Length Discrepancy Following Total Hip Arthroplasty.
- radiology of offset:
- horizontal and vertical offset depends on the the amount of acetabular reaming, femoral neck cut, inaddition to the modular components in
both the acetabular cup and femoral stem;
- the easiest way to judge offset is to compare Shenton's line of the opposite (normal hip) to the operative hip;
- a break in Shenton's line along with decreased area under the curve indicate decreased offset;
- Radiology of Acetabular Component:
- note that plain radiographs may be more accurate for identifying femoral component loosening than for acetabular loosening;
-
radiographic evaluation of cup position:
-
Judet views:
- cross table lateral:
- for evaluation of position of acetabular component (anteversion) & status of post bone stock in posterior column & neck of ilium;
- Lowenstein lateral radiograph:
- provides a lateral view of the acetabular subchondral bone and the cup after implantation
- modified Lowenstein lateral radiograph is similar to an
oblique radiograph of the pelvis;
- patient is turned onto the affected hip at least 45° and as much as necessary to allow the lower limb to be
in abduction and external rotation and to be flat on the x-ray table;
-
polyethylene wear (need to rule out
osteolysis w/ annual radiographs);
-
acetabular component loosening
- where as patients w/ loose femoral components will often complain of pain, in contrast, patients w/ loose acetabular
components may be asymptomatic;
- asymptomatic patients w/ radiographic evidence of loosening need to be followed for implant migration and loss of bone stock;
- some surgeons will recommend revision for radiographic loosening even if patients have no symptoms;
- Radiology of Femoroal Component: (
post op x-rays for thr)
- post op ap & lateral x-rays should include entire length of stem & cement mass;
- yearly radiographs need to be taken to look for progressive
osteolysis;
- radiographic views:
- frog leg lateral: gives best lateral of prox portion of femoral component;
-
stress views:
- may detect implant loosening;
- weight bearing and non wt bearing views:
- push pull views: to evaluate for loosening of components;
- same as ap view of hip w/ examiner providing distraction and compression to the hip thru the femur;
-
implant migration (indicates loosening);
-
pistoning / subsidence:
-
medial midstem pivot
-
calcar pivot: (distal toggle)
-
bending cantilever (distal pivot)
-
cemented femoral component:
- femur and cement column are inspected carefully and compared w/ previous films for changes indicating component
loosening, stem failure, trochanteric problems, or infection;
-
uncemented femoral component:
- end of stem pain is usually present from time of surgery, tends to improve during 1st year, but may remain constant thereafter;
- although bone scans may help, many noncemented THR, esp long stems, may show some increase in activity;
- divergent radiolucent lines in area of ingrowth indicate loosening;
-
varus / valgus positioning:
- traditionally, varus positioning has been thought to lead to premature loosening;
- in the report by Sochart and Porter 1997, however, neither varus or valgus stem position appeared
to be associated w/ premature stem loosening (w/ average of 20 years follow up);
- Misc:
-
heterotopic ossification:
The histology of the radiolucent line.
The long term results of Charnley Low Friction Arthroplasty in Young Patients who have Congenital Dislocation, Degenerative Osteoarthritis, or Rheumatoid Arthritis.
DH Sochart and ML Porter. JBJS Vol 79-A. No 11. Nov 1997. p 1599.
Iliopsoas tendon dysfunction as a cause of pain after total hip arthroplasty relieved by surgical release.
