High Hip Center Research Articles

Total Hip Replacement for the Dislocated Hip

Replacing the dislocated hip is technically more challenging than replacing the subluxated hip. Overall, clinical and radiographic results have not been as good for hips that are completely dislocated. The surgical approach must allow for identification of the false and true acetabula, identification of the sciatic nerve, and lengthening of the leg. In patients with a dislocated hip who are managed with total hip replacement, coverage of the cup can be achieved by medialization, creation of a high hip center, or use of a structural graft. Bone grafting allows the cup to be placed in an anatomic position, provides bone stock for additional surgery, and restores leg length. Our results and the results of other authors confirm that these grafts remain intact for at least 10 years and restore bone stock for additional surgery. This is particularly important in this relatively young population.

成人脱臼性股関節症に対する転子下短縮骨切りを併用した人工股関節全置換術（ＴＨＡ）の経験

Complete congenital dislocation of the hip is one of the most challenging reconstructions in hip arthroplasty. The distorted anatomy in this hip include a high hip center, a small femoral canal, leg length discrepancy, soft tissue contractures, and increased anteversion of the femoral neckshaft angle. Therefore, total hip arthroplasty in CDH has been associated with higher failure and complication rates.We report a case of total hip arthroplasty using subtrochanteric femoral shortening via transverse osteotomy unilateral high-riding congenital dislocation of the hip. This shortening technique was used with non-cemented components, reinforced with bicortical autograft struts and cables. Noncemented acetabular reconstruction was performed at the level of the true acetabulum without bone grafting.The time to union of the osteotomy site was 4 months. JOA scores improved from 52 points preoperatively to 76 points at the latest follow-up at 6 months after surgery.

Acetabular revision after failed total hip arthroplasty in patients with congenital hip dislocation and dysplasia. Results after a mean of 8.6 years.

Revision of a total hip arthroplasty in a patient who has had congenital hip dysplasia or dislocation is often more difficult than a standard revision operation. The purpose of this study was to assess the efficacy and complications of use of a cementless hemispherical acetabular component for revision of an acetabular component of a failed total hip replacement in patients whose initial problem was arthritis secondary to congenital dislocation or dysplasia. The mean duration of follow-up was approximately eight years. We reviewed a consecutive series of sixty-one hips in fifty-three patients who underwent a cementless acetabular revision with use of a hemispherical acetabular component, with or without concurrent femoral revision. Data were collected prospectively. The mean age of the patients at the time of the index operation was fifty-six years. A mean of 1.9 ipsilateral hip operations had been performed previously. Thirty-nine hips (64 percent) had a so-called high hip center prior to the index revision. With one exception, the uncemented acetabular component was fixed with screws. Fifty-one acetabular components were placed with so-called line-to-line fit, and ten were oversized by one to three millimeters. In thirty-eight hips, the femoral component was revised as well. Twenty-nine femora were reconstructed with use of a cemented device, and nine were revised with an uncemented patch-porous-coated femoral stem (a stem on which the porous coating appears in patches). Four patients (five hips) died prior to the five-year minimum follow-up interval. With the exception of one hip treated with resection arthroplasty because of deep infection, none of the hips in these deceased patients had been revised or had a loose component. One living patient (one hip) had a resection arthroplasty, and one additional patient (two hips) had both stable acetabular components rerevised at the time of femoral rerevision at another institution because of loosening and osteolysis. One patient refused to return for follow-up, but the components had not been revised. The remaining fifty-two hips in forty-six patients were followed for a mean of 8.6 years (range, 5.0 to 12.7 years). The mean Harris hip score was 80 points (range, 56 to 100 points) at the time of the latest follow-up. No acetabular component had been revised, although two had migrated. No other acetabular component was loose according to our radiographic criteria. Thus, the mechanical failure rate on the acetabular side was 3 percent (two of sixty-one) for the entire series and 4 percent (two of fifty-two) for the patients who had been followed for a mean of 8.6 years. On the femoral side, the mechanical failure rate was 3 percent (one of twenty-nine) for the cemented stems and six of nine for the uncemented patch-porous-coated stems. Of the approaches used in this difficult series of patients requiring revision, the hybrid arthroplasty (a cementless acetabular component and a cemented femoral component) yielded overall good results after an intermediate duration of follow-up.

The use of oblong acetabular components in complex acetabular reconstructions

Superior acetabular defects that are combined cavitary and segmental (American Association of Orthopaedic Surgeons [AAOS] type III) can be reconstructed with oblong acetabular components and have several theoretical advantages to the previously described techniques that use high hip center or bulk allografts. The indications and technique of oblong cup acetabular revisions is presented. The results have been favorable with 67% good to excellent clinical results and a 100% survivorship at a minimum 5-year follow-up.

High placement of an acetabular component inserted without cement in a revision total hip arthroplasty. Results after a mean of ten years.

Revision of an acetabular component in a patient who has severe periacetabular bone loss is a complex problem, particularly when there is not enough bone stock to allow placement of an acetabular component near the normal anatomical hip center. A valuable option for revision in such a situation is placement of a hemispherical shell, fixed with screws and without cement, against the superior margin of the acetabular defect. The resulting hip center is more proximal than that seen following a typical primary total hip replacement. Forty-six hips in forty-four patients were treated consecutively, between July 1984 and February 1988, with a revision in which a hemispherical acetabular component was fixed with screws and without cement. All shells but one were placed with a so-called line-to-line fit. The procedures resulted in a so-called high hip center--that is, the center of rotation of the revised hip was located at least thirty-five millimeters proximal to the interteardrop line. The mean age of the patients at the time of the index procedure was fifty-two years (range, twenty-five to eighty-one years). The most common diagnosis for which the original arthroplasty was performed was osteoarthritis secondary to congenital hip dysplasia or dislocation (twenty-two hips). Thirty-four hips had had a high hip center before the index revision, and most patients had had a substantial limb-length discrepancy, with a mean of 1.6 centimeters of shortening on the side of the operation. In thirty-three hips, the femoral component was replaced as well, with a long-neck or calcar-replacement stem used when necessary to maintain or increase the length of the limb. Six patients (six hips) died before the minimum eight-year follow-up interval; none had had another revision or loosening of the revised acetabular component. Of the remaining patients, four (four hips) had the implant removed. One of them had a resection arthroplasty and one of them had a hip disarticulation because of infection after a subsequent femoral reoperation. Another had a hip disarticulation because of late infection. The fourth implant was removed because it had displaced into the pelvis at approximately six years; this was the only reoperation for aseptic loosening in the series. The remaining thirty-six hips (thirty-four patients) were followed for a mean of 10.4 years (range, 8.5 to 12.7 years). One acetabular component migrated medially and was scheduled for revision. No other acetabular component was loose or had been revised. The mean Harris hip score was 81 points (range, 56 to 100 points) at the time of the most recent follow-up. Despite the use of a high hip center, the prevalence of a positive Trendelenburg sign was reduced from 98 percent (forty-five of forty-six hips) preoperatively to 44 percent (sixteen of thirty-six hips) at the time of the most recent follow-up. The short limbs were lengthened a mean of seven millimeters (range, five millimeters of shortening to forty millimeters of lengthening). In this study of acetabular revisions with use of a high hip center in patients who had major periacetabular bone loss, mechanical failure occurred in 4 percent (two) of the forty-six hips in the entire series and in 6 percent (two) of the thirty-six hips in patients who were alive and still had the implant in place after a mean of 10.4 years of follow-up. The use of a high hip center did not adversely affect function of the abductor muscles, and the mean limb-length discrepancy was reduced by the femoral reconstruction.

Reconstruction at a high hip center in acetabular revision surgery using a cementless acetabular component.

Reconstruction at a high hip center in acetabular revision surgery using a cementless acetabular component.

ROLE AND RESULTS OF THE HIGH HIP CENTER

Anatomic placement of the acetabular component should be the surgeon's goal at the time of revision THA. However, Acetabular loosening with subsequent implant migration, progressive superior acetabular bone destruction or severe pelvic osteolysis, may prevent the surgeon from obtaining adequate host bone-implant contact needed for a successful reconstruction while maintaining a normal hip center. The high hip center offers a technique for reconstruction of an acetabulum with severe bony deficiency and where the majority of the remaining host bone is superior to the anatomic hip centre.

Influence of a high hip center on abductor muscle function.

In 20 anatomic specimens with an acetabular defect (type Paprosky 3b), an acetabular component was implanted in the position of a high hip center. The vertical migration of the hip center ranged between 13 and 35 mm. It was accompanied by a lateralization and ventral migration of between 5 and 25 mm. The influence on the different abductor muscles was calculated through computer model comparing muscle force and muscle length before and after implantation of a high hip center. The increase in length of the gluteus maximus muscle and the posterior part of the gluteus minimus muscle ranged between 1% and 6%, while all other evaluated abductor muscles were shortened from 3% to 16%. The effect of the simultaneous changes of the lever arms was an increase in necessary muscle strength for pelvic stabilization from 140% to 250% compared with the original estimated strength prior to implantation. This may lead to insufficiency of the abductor muscles after placement of a high hip center. On the basis of these findings, we do not recommend the implantation of an acetabular component in the position of a high hip center.

Total Hip Replacement Using High Hip Center in Osteoarthritis Secondary to Hip Dysplasia(Preliminary study)

Total Hip Replacement Using High Hip Center in Osteoarthritis Secondary to Hip Dysplasia(Preliminary study)

High placement of porous-coated acetabular components in complex total hip arthroplasty

The authors retrospectively evaluated the results of 56 hips in 51 patients with an acetabular deficiency who had a total hip arthroplasty with a porous-coated, cementless acetabular component implanted at a high hip center. Forty-nine cases were revisions and seven were primary operations. The mean height of the hip center was 43 mm above the interteardrop line compared to 14 mm for the anatomic center, threefold higher than normal. In contrast, the mean horizontal locus was reduced compared to normal (33 vs 37 mm for the anatomic center). Sixteen acetabular components were small (46–48 mm o.d.) and eight were miniature (40–44 mm o.d.). Despite superior placement of the acetabular component, 32 limbs were lengthened by the procedure. The mean preoperative Harris hip score was 51 (range, 28–93). At a mean follow-up period of 40 months (range, 24–64 months), the mean Harris hip score was 86 (range, 36–100). In 23 hips no radiolucent lines were present at the interface of the bone to the porous mesh, and 33 hips had a thin (0.5 mm), nonprogressive radiolucent line in one or more zones. No acetabular component had migrated and no problems occurred with the screws. Four hips (3 revisions and 1 primary operation) had a complete radiolucent line on one oblique view of the acetabulum. No acetabular component has been revised for loosening. These short-term data suggest that under circumstances in which the acetabulum cannot be reconstructed at the anatomic level without a major structural bone-graft, superior placement of the porous-coated acetabular component against viable host-bone at a higher level than normal may be an acceptable alternative.

Vascular Complications of Orthopaedic Surgery

The role of allograft tissue, including bone, cartilage and soft tissue, has become more defined in lower extremity reconstructive surgery. Revision arthroplasty of the hip commonly requires restoration of bone stock using allograft bone. Morcellized bone is used for contained defects on both the acetabular and femoral sides. Structural allograft bone is used for uncontained or segmental defects, and the results are less predictable; therefore, its use is more controversial. Alternatives include the jumbo cup, oblong cup, and high hip center on the pelvic side and tumor prostheses or distal fixation on the femoral side. These alternatives do not, however, restore bone stock, thus making further surgery more difficult. Structural grafts allow attachment of bone and soft tissue and restoration of the correct anatomy and have been shown to restore bone stock for further surgery, particularly on the acetabular side. Improvements in the quality and safety of banked bone and the development of surgical techniques have enhanced the results of structural allograft bone grafting. Restoring bone stock in revision arthroplasty of the hip is an accepted standard for the patient likely to undergo further surgery. Continuing to develop technologies that will facilitate the use of allograft tissue is imperative.