Nas S. Eftekhar

Osteolysis after Charnley primary low-friction arthroplasty

We reviewed 249 consecutive Charnley primary low-friction arthroplasties in 191 patients performed by one surgeon using a transtrochanteric approach at a minimum follow-up of ten years. Of these, 37 hips in 32 patients showed osteolysis and were compared with 41 hips in 37 matched patients with no osteolysis. We assessed in each case the wear rate, stability of the prosthesis, acetabular angle, socket angle, thickness of the acetabular and femoral cement mantle, canal flare index, femoral score, stem alignment, implant:canal ratio and stem:canal ratio. We found that a high rate of wear, component instability and osteolysis were associated. Osteolysis was three times more common in men than in women. Factors which reduced osteolysis were cement mantles of 6 mm at the acetabulum and of 3 mm in all zones of the femur, a stem:canal ratio of 60% to 70% and an implant:canal ratio of over 99%. The overall incidence of osteolysis was 14.9% but when these technical criteria were met, the incidence was 5.2%. This suggests that careful technique can dramatically reduce the risk of this complication.

Postoperative Sciatic and Femoral Nerve Palsy With Reference to Leg Lengthening and Medializatiod Lateralization of the Hip Joint Following Total Hip Arthroplasty

The radiographs and prospective records of 1284 (1152 primary and 135 revisions) Charnley low friction arthroplasties performed by one surgeon were studied in reference to postoperative elongation of the limb and lateralization or medialization of the center of rotation of the hip joint and their effect on postoperative nerve palsy. Displacement of the center of the hip joint in relation to fixed points on the pelvis was measured. In primary low friction arthroplasties, leg lengthening ranged from 0.4 to 4 cm; in the revision group, they ranged from 0.04 to 5.8 cm. Sixty-six hips were lengthened more than 2 cm. The center of rotation of the hip was lateralized in 18.1% of cases and medialized in 61.9%. A single case of postoperative sciatic nerve palsy (the result of laceration of the sciatic nerve at surgery) was identified. These study results indicate that nerve injuries after total hip arthroplasty may be caused by local insult, and may not be related to elongation of the limb or postoperative alteration of the center of rotation of the hip.

Comparative Study of Total Hip Arthroplasty Between Younger and Older Patients

Ten- to 20-year (average, 14 years) results of primary Charnley low friction arthroplasties performed in patients 50 years of age or younger (55 sockets and 53 femoral prostheses) were compared with those in patients older than 50 years (273 sockets and 273 femoral prostheses). The incidence of radiologic loosening of the socket, including revision cases, was higher in the younger (29.1%) than in the older patients (14.3%). The revision rate for aseptic loosening of the socket was higher in the younger (20%) than in the older group (4%). This poor performance of the socket may be attributable to the higher incidences of rheumatoid diseases and accelerated polyethylene wear in the younger patients. In contrast, only 3.8% of the femoral prostheses were radiologically loose, and none of them were revised in the younger patients. These figures were comparable with those in the older patients. Quality or structure of bone available for implant fixation may be important for the durability of the arthroplasty. It was considered inferior on the acetabular side and better on the femoral side in the younger patients than in the older. Continued use of the cemented Charnley femoral prostheses can be justified in young patients, although further research is required for the socket problem.

Intrapelvic migration of total hip prostheses. Operative treatment.

We describe a safe operative approach for removal of a prosthesis that has migrated into the pelvis, and we recommend that a two-stage reconstruction be done when revising the total hip-replacement arthroplasty. The first stage consists of the removal of the femoral component and cement through a lateral transtrochanteric approach, followed by removal of the acetabular component through an abdominal-retroperitoneal approach to permit exposure of the major intrapelvic structures and to ascertain their relationship to the acetabular component and cement. After the acetabular component has been removed, bone grafts are applied to the pelvis. Postoperatively, the patient is placed in traction for a time and then is allowed to walk with non-weight-bearing. The second stage of reconstruction, consisting of hip replacement, is performed nine to twelve months after the first stage. A satisfactory result was obtained in the four patients for whom we followed this operative regimen. In one patient, the first-stage procedure yielded a satisfactory result and the second stage was not done.

Trochanteric osteotomy and wire fixation: a comparison of 2 techniques.

Between 1986 and 1989,190 patients (214 hips) with the diagnosis of osteoarthritis or posttraumatic arthritis underwent cemented Charnley total hip replacement surgeries via the biplane or single plane transtrochanteric approach. The technique of surgery was identical in every aspect except for the technique of the trochanteric osteotomy and reattachment. The results indicate that there was no significant difference in union rates between the 2 groups. Six (6.4%) patients in the biplane group and 7 (6.2%) patients in the single plane group had obvious evidence of nonunion at the 1-year evaluation. This study suggests no significant difference in union rate between a group of patients with biplane osteotomy and a closely paired group of patients with single plane osteotomy. Other equally important factors also may influence the rate of union of the trochanter in total hip arthroplasty.

Long term bone remodeling around the Charnley femoral prostheses

Femoral bone remodeling after total hip replacement was studied by following patients who received 326 Charnley femoral prostheses for 10 to 20 years (mean, 13.3 years). The radiographic state of bone remodeling was visually assessed and measured with a digitizer. Demineralization that started proximally and then progressed distally caused cortical thinning, which correlated with widening of the intramedullary canal, not with changes that developed in the periosteal width, and occurred in the medial femoral neck, around the proximal half of the stem, and around the distal half in 87%, 33%, and 10%, respectively. Cortical thinning around the distal half of the stem was always accompanied by proximal thinning, and extensive cortical thinning (both proximal and distal) correlated with both lower clinical scores and radiologic loosening of the femoral prosthesis. A low canal flare index of Noble, a large canal width, and a patient age of 60 years or more were risk factors for extensive cortical thinning. Accelerated polyethylene wear was related to resorption of the medial femoral neck but not to cortical thinning or radiological loosening. Cortical thickening occurred only around the distal half of the stem in 29%. These findings establish a basis for the performance of cemented femoral prostheses, and allow comparison of bone remodeling when evaluating other femoral prostheses.

Influence of demographic and technical variables on the incidence of osteolysis in Charnley primary low-friction hip arthroplasty.

The influence of demographic and technical variables on the incidence of osteolysis in Charnley primary low-friction arthroplasty was investigated. Demographic variables included age, gender, diagnosis, and Charnley joint class. Technical variables included the design of acetabular and femoral components, subchondral plate retention versus removal, and cementing techniques. We analyzed 633 hips (in 494 patients) implanted by a single surgeon between 1970 and 1984 using Kaplan-Meier survival graphs. Radiographically determined osteolysis was defined as the end point. The incidence of osteolysis at 5 years was 2% (confidence interval [CI] +/- 0.5%); at 10 years, 8% (CI +/- 1.6%); at 15 years, 15% (CI +/- 2.2%); and at 20 years, 17% (CI +/- 3.5%). Younger patients (age < 65 years) and men were both found to have a significantly increased incidence of osteolysis (P<.05). No significant association with osteolysis was found for the other demographic and technical variables investigated. Osteolysis predates loosening and failure of hip arthroplasty. Regular assessment with the goal of earlier identification, especially in higher risk younger and male patients, is important to avoid excessive bone loss and technical difficulties in revision surgery.