painful total hip replacement

A 79-year-old female with a history of a left total hip replacement performed 10 years ago presents with worsening hip pain. The pain began 1 year ago when she noted progressive activity-related groin pain. She denies any trauma. The patient denies fever. She does not have night pain. A radiograph is shown in Fig 7–15 above. The patient has started using a walker.

 

 

 

Figure 7–15

 

What should be the next step in the evaluation of this patient?

1. Bone scan

2. Serum, ESR, and CRP

3. Metal ion testing including chromium levels

4. Physical therapy for abductor strengthening

5. Preoperative anesthesia evaluation before revision surgery

 

Discussion

The correct answer is (B). Despite the absence of fever and nocturnal pain, which if present would be associated with infection, infection should still be ruled out. A screening ESR and CRP helps determine the need for further aspiration.

The original Charnley hip replacements involved a cemented femoral component and cemented all-polyethylene acetabular cup with a 22-mm head. Recent 30-year follow-up data on the Charnley total hip replacement revealed that the leading reason for revision was:

1. Acetabular loosening

2. Femoral stem loosening

3. Both component loosening

4. Infection

 

Discussion

The correct answer is (A). Wroblewski et al. (2009) have reviewed 110 patients who underwent THR with the original Charnley prosthesis and have more than 30 years of follow-up; 11.8% (13 patients) required revision. The primary reason for revision in this series was acetabular component loosening. Both component loosening, infection, and loose stem followed in terms of prevalence for revision.

Based on the images above, the patient has superior acetabular bone loss with a combination of segmental and cavitary bone loss. According to the system designed by the American Academy of Orthopaedic Surgeon, this pattern of acetabular bone loss would be classified as:

1. AAOS type I

2. AAOS type II

3. AAOS type III

4. AAOS type IV

5. AAOS type V

    

   Discussion

   The correct answer is (C). The two most commonly used classification systems for the evaluation of acetabular bone loss following THR include the AAOS classification and the Paprosky classification for bone loss around the acetabulum. The classification systems are useful in providing some insight in further reconstruction options.

   AAOS classification:

   1. Segmental bone loss involving part of the acetabular rim or medial wall

   2. Cavitary bone loss with preservation of good rim fit but volumetric loss

   3. Combination of segmental and cavitary bone loss

   4. Pelvic discontinuity with separation between superior and inferior acetabulum

   5. Arthrodesis Paprosky classification:

1. Minimum deformity, intact rim

2. A. Superior lysis but intact rim. B. Absent superior rim with superior migration.

   C. Medial wall destruction and migration

3. A. Bone loss from 10 to 2 PM with superolateral migration. B. Bone loss from 9 to 5 PM with superomedial migration

   This patient describes groin pain typically associated with acetabular component. In the case of a patient with extensive thigh pain and an x-ray showing metadiaphyseal bone loss with a minimum of 4 cm of intact cortical bone, this femoral lesion would be classified as:

   1. Paprosky type I

   2. Paprosky type II

   3. Paprosky type IIIA

   4. Paprosky type IIIB

   5. Paprosky type IV

       

      Discussion

      The correct answer is (C). Similar to the AAOS classification for acetabular bone loss, the Paprosky classification allows for estimation of bone loss as well as reconstruction options available.

      AAOS classification:

      1. Segmental—loss of cortical bone

      2. Cavitary—loss of endosteal bone with cortex intact

      3. Combination of segmental and cavitary bone loss

      4. Malalignment due to previous trauma or disease

      5. Obliteration of canal due to trauma, fixation devices, or bone hypertrophy

      6. Fracture or nonunion

         Paprosky classification:

         I: Minimal metaphyseal bone loss

         II: Extensive metaphyseal bone loss with intact diaphysis

         IIA: Extensive metadiaphyseal bone loss with a minimum of 4-cm diaphyseal bone IIB: Extensive metadiaphyseal bone loss with more than 4-cm diaphyseal bone loss IV: Nonsupportive diaphysis

         Surgical preparation involves evaluation of the clinical scenario and interpretation of all available results. In complex hip reconstruction such as this, additional studies may help with preoperative planning and preparation. If concerned, additional helpful imaging may involve:

         1. Bone scan

         2. MRI hip

         3. CT of pelvis

         4. Judet views

         5. Arthrogram

 

Discussion

The correct answer is (C). Bone loss is often underestimated on typical x-rays. A CT allows for further understanding of the involved anatomy and appropriate preparation including the availability of augments, cages, jumbo cups, and any other reconstruction equipment necessary.

The reconstruction of the acetabulum involves an evaluation of the rim fit and the appropriate material to be used for reconstruction. The use of structural bone allograft has been associated with:

1. High failure rate with component migration

2. Low failure rate with bone ingrowth

3. Decrease in the use of cages for pelvic discontinuity

4. Use in cups where rim is competent with good press-fit

5. Increased viral transmission

 

Discussion

The correct answer is (A). Until the recent introduction of trabecular metal augments and other reconstruction methods, structural allograft had been used extensively for acetabular reconstruction. When a good rim fit is obtained with the

acetabular component, morselized bone graft and reamings can be used to pack any cavitary lesions behind the cup. Large structural/cortical allograft in the pelvis has been associated with most failures with subsequent resorption and cup migration.

The reconstruction options in this patient based on original x-rays involves:

1. Both component revision

2. Acetabular revision with allograft

3. Acetabular revision with augments

4. Liner exchange and retroacetabular bone grafting

5. Continue observation with repeat x-rays in 6 months

 

Discussion

The correct answer is (C). This patient requires acetabular revision at minimum. The femoral component appears in slight varus however no signs of osteolysis or component migration are seen.

On the acetabular side, the patient shows both segmental and cavitary losses but no suggestion of pelvic discontinuity. Further imaging may be helpful. In cases where the cup is in good position with signs of polyethylene wear and retroacetabular lysis, liner exchange and bone grafting through the screw wholes has been documented with good results. In this case, reconstruction with a jumbo cup, with or without augments to provide superior support, should reestablish normal cup position and geometry.

In cases of a Paprosky IIIA femur as discussed earlier, the viable reconstruction would involve:

1. A tapered stem with proximal ingrowth surface

2. A porous coated diaphyseal engaging implant

3. Extended trochanteric osteotomy with cemented long stem implant

4. Calcar replacing tapered stem

5. Megaprosthesis

 

Discussion

The correct answer is (B). A porous-coated diaphyseal engaging femoral stem is associated with over 95% survivorship at 10 years. Calcar replacing stems and megaprosthesis are each viable options in patients with calcar loss or loss of diaphyseal bone respectively, but are not the best option in the described defect.

Helpful Tip:

The initial evaluation of a painful total hip replacement should focus on all aspects of pain around the hip including infection and referred pain due to spinal pathology. The duration of symptoms may help delineate between progressive failure of the THA versus infection or new fracture. Components should be evaluated for position as well as radiographic signs of lucency. A determination of stability should be made based on extent of lysis and migration.

Once the decision for revision has been made, a clear plan should be outlined regarding the methods of reconstruction as well as alternatives in case more extensive pathology is noted. AAOS or Paprosky classifications help categorize the pathology and define a plan of action. The surgeon should be prepared to revise both components if intraoperative findings including component position require it.

 

Objectives: Did you learn...?

 

 

Evaluate a painful total hip replacement and consider a differential? Identify lysis around components and classify the degree of bone loss?

 

Produce a viable management approach for reconstruction including an understanding of structural bone graft, augments, cages, and use of jumbo cups?