Total Hip Arthroplasty

Fig. 11.1

In this patient who was initially treated nonoperatively for an acetabular fracture, she has developed posttraumatic osteoarthritis with a severe protrusio defect. Given the deformity of her left hip, we template the right hip using standard landmarks to give us an idea of how to proceed with our reconstruction. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

Often times, these patients present with significant leg shortening. Because the protrusio deformity and leg shortening were not a development abnormality, but rather a change that occurred in adulthood, we have not seen sciatic nerve palsies from lengthening the hip at the time of conversion hip replacement . If patients have severe shortening without a flexion contracture, then a posterior approach to the hip may facilitate lengthening the leg to be equal to the contralateral side. If the patient presents with a severe flexion contracture, then a Hardinge, Watson-Jones, or direct anterior approach to the hip may be preferred.

In some cases, the hip can be dislocated with femoral head and neck intact; however, in many cases, an in situ neck cut prior to dislocation is necessary, which should be made at the templated distance above the lesser trochanter.

The femoral head neck remnant can be removed from the acetabulum using a corkscrew; however, sometimes in these cases the femoral head and neck are very osteoporotic and need to be shelled out of the acetabulum with a rongeur.

The femoral head neck should be saved for autograft of the cavitary defects that are present.

After removal of the femoral head, the femur is prepared using the standard technique. Attention is turned to the acetabulum. There is usually fibrous tissue present on top of the subchondral bone that we remove using a large straight curette and if there is any hyaline cartilage still attached to the deeply impacted portions of the acetabulum, we remove this cartilage with a curette as well, so that no articular cartilage is present in the acetabulum.

We are certain to remove the labrum and locate the transverse acetabular ligament to get some guide for component placement. However the transverse acetabular ligament position should not be the only guide for the surgeon as it may be deformed from its original position.

We then begin gentle reaming at or near the templated size of the acetabulum for a “rim fit.” This means that we do not ream deeply into the protrusio defect, but rather attempt to place the acetabular component in the more lateralized position as equivalent as possible to where it would be it in the native hip.

While reaming this rim fit, it is very important not to let the reamer sink into the acetabulum. Some surgeons prefer to do this reaming on reverse, borrowing from techniques originally used for treatment of protrusio defects in rheumatoid arthritis.

An acetabular trial is then impacted in place to make sure that we have a good fit around the acetabular component and this position is checked on fluoroscopy to make sure that it correlates with our clinical impression of cup placement.

The bone grafting technique that is used for grafting the medial defects should be done meticulously to provide a firm bed to provide additional support against medial settling of the acetabular component [1, 2].

The femoral head is morselized into three different sizes of particulate allograft roughly 8 mm, 5 mm, and 2 mm in diameter and then mixed with vancomycin. We place this graft through the fenestrations in the acetabular window trial and then remove the acetabular trial and reverse ream the graft to create a stable bed (Figs. 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, and 11.8).

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig2_HTML.jpg — Fig. 11.2

The native or allograft femoral head is secured with a Weber tenaculum over top several layers of blue operating room towels. A saw is used to section the femoral head into quadrants or even octants to create our impaction graft. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig3_HTML.jpg — Fig. 11.3

A rongeur is used to create a large fragments of bone graft and medium fragments of bone graft. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig4_HTML.jpg — Fig. 11.4

A small acetabular reamer is used to create fine particles of impaction bone graft. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig5_HTML.jpg — Fig. 11.5

Ideally three separate sizes of bone fragments are created to optimize mechanical properties of the particulate impaction graft. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig6_HTML.jpg — Fig. 11.6

Powdered antibiotic, usually 1 g of vancomycin powder, can be added to our impaction graft. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig7_HTML.jpg — Fig. 11.7

The impaction bone graft is reverse reamed into the acetabular defect. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig8_HTML.jpg — Fig. 11.8

This creates a firm medial substrate upon which to rest the acetabular component. Reaming for the acetabulum is completed to get a “rim fit” for the acetabular component. A trial acetabular component is then impacted in place and visual inspection through the fenestrations and the trial will determine whether enough medial bone graft has been placed to reconstitute the floor of the acetabulum. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

We then impact in place a standard multihole revision acetabular porous coated component. We then place four or five supplemental screws into the ilium and ischium to prevent abduction failure of the acetabular component (Fig. 11.9). Fluoroscopy is used to judge not only acetabular inclination but also the position of the inferior lip of the acetabulum relative to the teardrop.

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig9_HTML.jpg — Fig. 11.9

Pre- and postoperative radiographs show impaction grafting of the protrusio defect in an attempt to place the acetabular component near the correct hip center as compared to the contralateral side. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

This information is synthesized with the lesser trochanter to center distance to equalize leg lengths as much as possible judging from the templated contralateral uninjured hip.

Postoperative Care

In many cases the acetabular stability obtained by this technique is excellent and patients can begin full weight-bearing immediately after surgery. If there are concerns, the surgeon can keep the patient 50% weight-bearing for four to six weeks after surgery. Gradual languishment of assistive devices is encouraged. Patients are followed very closely for graft consolidation and usually this is reliable given the autograft femoral head that is utilized.

Conversion THA in Patients Who Have Had Previous ORIF

Patients who have had previous ORIF are substantially more complex with regard to conversion THA than patients who were initially treated nonoperatively. There is usually heavy scarring present from the previous surgical exposure. Frequently there are implants that may need to be removed that can be incarcerated in fibrous scar or bone, and there is a higher chance of occult infection surrounding these implants.

Infection is always in our mind when addressing these patients. Each patient who is indicated for a conversion hip replacement has a C-reactive protein and erythrocyte sedimentation rate drawn as well as a serum albumin and transferrin to assess nutritional status.

Our protocol at Shock Trauma is to have all these patients aspirated by the interventional radiology service. However, we would certainly not argue that this is a standard of care and aspiration may have limited utility. With the heavy scarring and joint space destruction that is present around these hips, it may be difficult to obtain fluid even in the face of infection from an aspiration alone.

If there is a suspicion of infection, but no objective serologic or aspiration evidence, then a “one-stage exchange” with removal of all fracture fixation implants and irrigation followed by reprep and redrape prior to hip implant placement is a prudent measure. We accomplish this in a fashion similar to “one-stage exchange” treatment for infected arthroplasty [3].

If there is a documented infection, we will usually discuss with the patient removal of all the deep implants and placement of a Prostalac (DePuy, Warsaw, Indiana) hip spacer with a later secondary stage reconstruction of the hip.

What Approach Should Be Used for the Hip Replacement

In general, the approach used for the hip replacement should be the surgeon’s preferred approach for normal primary total hip arthroplasty. However, the need for removal of retained implants may dictate a posterior approach in some cases.

In general, fracture fixation implants that have no suspicion of infection and would not appear to interfere with acetabular component placement do not need to be removed at the time of conversion THA.

In particular, implants that have been placed through an anterior intrapelvic (Stoppa) approach or ilioinguinal approach can present risks of bladder and vascular injury as well as hernia if removal is attempted. Long screws that interfere with acetabular reaming can be segmentally removed with a high-speed burr to minimize impingement on the acetabular component without frank removal of the plates and screws from inside the pelvis (Fig. 11.10).

../images/395168_1_En_11_Chapter/395168_1_En_11_Fig10_HTML.jpg — Fig. 11.10

A separate but similar case using impaction grafting of a large medial defect, in this case, the patient had previous plates and screws that were placed through an anterior intrapelvic approach. (Property of Theodore Manson and the R Adams Cowley Shock Trauma Center. Used with Permission)

If plates and screws inside the pelvis are predicted to interfere with acetabular component placement, then they can always be removed at the time of concomitant total hip replacement using the Levine extension of the direct anterior approach to the hip as outlined in Chap. 9 (Figs. 11.11, 11.12, 11.13, and 11.14) [4–6].