Michael R. O'rourke

Osteolysis associated with a cemented modular posterior-cruciate-substituting total knee design : five to eight-year follow-up.

Background: Most intermediate and long-term studies of cemented posterior-cruciate-substituting total knee prostheses were performed with nonmodular tibial components. The purpose of this study was to evaluate the intermediate-term results of posterior-cruciate-substituting total knee arthroplasties in which a cemented modular tibial component had been used, with a particular focus on evaluating the prevalence of radiographic osteolysis.Methods: Between 1992 and 1995, 176 consecutive primary total knee arthroplasties with use of the Insall-Burstein II system were performed in 134 patients at our institution. A modular metal-backed tibial component was inserted in 145 knees, and an all-polyethylene tibial component of the same design was inserted in thirty-one. Standard-terminology questionnaires were completed or Knee Society and The Hospital for Special Surgery scores were determined preoperatively and at the time of final follow-up, at an average of 6.4 years (range, 5.0 to 7.9 years). Initial postoperative radiographs were compared with those made at the time of final follow-up to assess component position, wear, radiolucent lines, and osteolysis.Results: Ninety-two patients (128 knees) treated with the modular tibial component were alive at the time of final follow-up. No patient was lost to follow-up. Radiographs were available for 105 knees (82%). Three knees had been revised because of instability or infection; none had been revised because of loosening or osteolysis. The mean Knee Society clinical and functional scores were 85 points (range, 41 to 100 points) and 79 points (range, 30 to 100 points), respectively, at the time of final follow-up. According to The Hospital for Special Surgery score, 94% of the knees had a good or excellent result. Knee flexion averaged 113° (range, 90° to 130°) at the time of final follow-up. Osteolysis was present in seventeen (16%) of the knees with radiographic follow-up. Osteolysis did not develop in any knee in which an all-polyethylene tibial component had been used. Two knees (in one patient) were revised because of osteolytic lesions found at the time of follow-up for the study. Both of these knees had anterior wear of the tibial post due to impingement and backside tibial polyethylene wear.Conclusions: Modular Insall-Burstein II total knee prostheses were found to function well after five to eight years of follow-up. However, the high prevalence of osteolysis in patients who had good or excellent clinical scores is worrisome. Particular attention should be paid to preventing flexion of the femoral component, posterior slope of the tibial component, or hyperextension of the knee when posterior-cruciate-substituting total knee arthroplasty is performed. We also recommend routine follow-up radiographs after all total joint arthroplasties to detect asymptomatic osteolytic changes.

Tibial post impingement in posterior-stabilized total knee arthroplasty

Reports of posterior-stabilized total knee replacements have shown excellent clinical success. However, tibial post-femoral cam impingement has been seen in modular component retrievals. This finding has been associated with transmission of rotational forces to the modular tray-polyethylene interface with subsequent backside polyethylene wear and the development of osteolysis. Femoral cam-tibial post designs that allow hyperextension and limit rotational constraint may minimize this impingement. Technical considerations including the avoidance of femoral component flexion and posterior tibial slope will minimize anterior tibial post impingement.

The John Insall Award: unicompartmental knee replacement: a minimum twenty-one-year followup, end-result study.

We report the results of a minimum 21-year followup of a consecutive series of 103 patients who had 136 Marmor cemented unicompartmental knee replacements done between 1975 and 1982. Patients were evaluated clinically and radiographically. At minimum 21-year followup 14 patients (19 knees) were alive, 87 patients (115 knees) had died, and only two patients (two knees) were lost to followup. The average age at surgery was 70.9 years. The average followup Hospital for Special Surgery knee score was 58. The average Knee Society final followup clinical and functional scores averaged 72 and 53 points, respectively. Nineteen knees (14%) were revised during the 21-year followup period: nine for progression of disease, eight for loosening, and two for pain, at an average of 10.6 years (range, 1-22 years). Of the 19 knees in the 14 patients who were still alive at final followup, seven (37%) were revised: two for tibial loosening, four for disease progression, and one for pain. Unicompartmental knee replacements in this relatively older age group of patients performed well at minimum 21-year followup. Although we are encouraged by these results, only 22% were done in patients who were younger than 65 years at the time of surgery and the results in this group were significantly less durable. Level of Evidence: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

The treatment of acetabular bone defects with an associated pelvic discontinuity.

Pelvic discontinuity is encountered frequently during acetabular revision in patients with severe acetabular bone loss. Prompt recognition of the discontinuity and appropriate intraoperative treatment are essential for a successful clinical outcome. The treatment of the discontinuity is dependent on the remaining host bone, the potential for healing of the discontinuity, and the potential for biologic ingrowth of acetabular components. If healing potential of the discontinuity exists, the discontinuity should be treated in compression with a posterior column plate and structural allograft or with the use of trabecular metal acting as an internal plate. If healing potential for the discontinuity does not exist, the discontinuity should be bridged and treated in distraction with an acetabular transplant supported with a cage, a trabecular metal component with trabecular metal augmentation, or with the use of a custom triflange implant. Level of Evidence: Therapeutic study, Level III-1 (case-control study). See the Guidelines for Authors for a complete description of levels of evidence.

Use of a Constrained Tripolar Acetabular Liner to Treat Intraoperative Instability and Postoperative Dislocation after Total Hip Arthroplasty: A Review of Our Experience

Constrained acetabular components have been used to treat certain cases of intraoperative instability and postoperative dislocation after total hip arthroplasty. We report our experience with a tripolar constrained component used in these situations since 1988. The outcomes of the cases where this component was used were analyzed for component failure, component loosening, and osteolysis. At average 10-year followup, for cases treated for intraoperative instability (2 cases) or postoperative dislocation (4 cases), the component failure rate was 6% (6 of 101 hips in 5 patients). For cases where the constrained liner was cemented into a fixed cementless acetabular shell, the failure rate was 7% (2 of 31 hips in 2 patients) at 3.9-year average followup. Use of a constrained liner was not associated with an increased osteolysis or aseptic loosening rate. This tripolar constrained acetabular liner provided total hip arthroplasty construct stability in most cases in which it was used for intraoperative instability or postoperative dislocation.

Managing Bone Loss in Acetabular Revision

The management of bone loss encountered during acetabular revision remains challenging. In order to obtain a successful surgical result, preoperative planning is required to estimate the severity and location of bone defects. Most acetabular revisions can be treated with the use of a cementless hemispherical component. However, a successful surgical reconstruction requires component stability. Depending on the degree of bone loss, the surgical reconstruction may require the use of cancellous or structural bone graft, acetabular augmentation, an acetabular cage, a custom implant, or an acetabular transplant.

Total hip arthroplasty with cement and use of a collared matte-finish femoral component: nineteen to twenty-year follow-up.

BACKGROUND In the mid- to late 1970s, on the basis of laboratory and finite element data, many surgeons in the United States began using collared matte-finish femoral components and metal-backed acetabular components in their total hip arthroplasties. The purpose of this study was to evaluate the long-term results of the use of one such construct in arthroplasties performed by a single surgeon in a consecutive nonselected patient cohort. METHODS Between January 1984 and December 1985, 273 patients underwent a total of 304 consecutive nonselected total hip arthroplasties with cement and use of the Iowa femoral component (which is collared, has a proximal cobra shape, and has a matte finish) and a metal-backed TiBac acetabular component performed by a single surgeon. At nineteen to twenty years postoperatively, only two patients (two hips) were lost to follow-up. For clinical evaluation, we attempted to interview all living patients and the families of the patients who had died to verify the status of the hip prosthesis or any revisions. Radiographic evaluation consisted of analysis for loosening and osteolysis as well as wear of the acetabular component. RESULTS At the time of the nineteen to twenty-year follow-up, the rate of revision of the arthroplasty for any reason was 10.5% (thirty-two hips) for all patients and 25% (twenty-three hips) for living patients. The rate of revision due to aseptic femoral loosening was 2.6% (eight hips). There was radiographic evidence of loosening of the femoral component in fifteen hips (4.9%), including those that were revised, and femoral osteolysis was seen distal to the trochanters in twenty-two hips (7.2%). The rate of revision due to aseptic loosening of the acetabular component was 7.9% (twenty-four hips), and there was radiographic evidence of acetabular loosening in forty-two hips (13.8%), including those that were revised. CONCLUSIONS This study demonstrates the durability of a cemented matte-finish collared femoral component at twenty years postoperatively, with a rate of revision due to aseptic loosening of 2.6%. The metal-backed acetabular component also performed well in many patients, with a 7.9% rate of revision due to aseptic loosening. However, in the living patients, the rate of loosening of the acetabular component, including cases revised because of aseptic loosening, was 30.4%.

Variances in sagittal femoral shaft bowing in patients undergoing TKA.

We asked, “What are the quantitative variances in sagittal femoral bowing in patients who were indicated for total knee arthroplasty?” We retrospectively evaluated 145 consecutive patients who underwent 166 primary total knee arthroplasties with adequate preoperative nonrotated sagittal plane full-leg lateral radiographs. Digital radiographs were processed such that each femoral shaft was divided into three segments. A purpose-written program determined the flexion/extension of the femoral component using the Knee Society method of focusing on the distal femur and a second method using the whole femur. The median angle of curvature of the proximal, middle, and distal thirds of the femora were 5.4°, 0.2°, and 3.1°, respectively, with the largest bow occurring in the proximal segment followed by the distal segment and with the least bow in the middle segment. The median angles for femoral component flexion were considerably different with the whole femur angle showing more flexion (4°) than that of the Knee Society angle (1.421°). We found an inverse relationship between distal angle of curvature and height as well as weight. Men had greater proximal bowing and less distal bowing than women. The effects of these variances may have implications in development of osteoarthritis and total knee arthroplasty component survival.

Osteonecrosis following isolated avulsion fracture of the greater trochanter in children. A report of two cases.

Isolated avulsion fracture of the greater trochanter is a rare condition in both adults and children 1-3. Injury to the proximal part of the growing femur has been associated with osteonecrosis of the epiphysis and metaphysis, particularly with epiphyseal separation and fracture of the femoral neck 4-6. The blood supply to the proximal femoral epiphysis has been well described by Trueta 7, Chung 8, and Ogden 9. Injury to the vulnerable posterolateral branches of the medial femoral circumflex artery has been implicated in the development of necrosis as a result of direct trauma, compression from an intracapsular hematoma, and iatrogenic injury during treatment 4-6,10-13. Kaweblum et al. 11 reported the case of a twelve-year-old child in whom treatment of an isolated avulsion fracture of the trochanter with open reduction and internal fixation resulted in osteonecrosis of the femoral epiphysis. We report the cases of two patients in whom osteonecrosis of the femoral epiphysis developed following an isolated avulsion fracture of the greater trochanter. One of the patients had minimal displacement and was managed nonoperatively; the other patient underwent a closed reduction and percutaneous screw fixation. In both cases, the trochanteric fracture healed; however, osteonecrosis of the femoral epiphysis developed in both. Case 1. While playing football, a healthy thirteen-year and one-month-old boy sustained a displaced avulsion fracture of the left greater trochanter ( Fig. 1-A ), which initially was treated with closed reduction and percutaneous cannulated screw fixation ( Fig. 1-B ) at another institution. The postoperative course included protected weight-bearing for six weeks followed by a gradual return to activities. The patient did well and was able to play basketball during the ensuing winter months. The screws were removed five months after the …

Association of third body embedment with rim damage in retrieved acetabular liners.

Third-body effects are a major cause of the substantial variability of wear in total hip replacements. One potential mechanism by which third-body debris can access wear-critical central regions of closely conforming metal-on-polyethylene bearing couples is by fluid convection during incidents of subluxation accompanying neck-on-liner impingement. To provide evidence for this premise, we determined the association of severity of liner rim indentation damage (indicative of impingement frequency/vigor) and the presence of embedded third-body debris in 194 implants retrieved at revision. Rim damage was graded using the five-point Hospital for Special Surgery scale. Particle embedment was assessed both manually and by means of an image analysis computer program that detected the composition, size, and location of each particle. Sixty-eight percent of the cups showed rim indentation damage. We found an association between severity of rim damage and presence of embedded debris. There was substantial nonuniformity of the spatial distribution of the embedded debris, with the predominance of embedded debris at intermediate latitudes. These findings support the premise of convection of debris-laden joint fluid during lever-out subluxation as a mechanism for wear-consequential third-body particles to gain access to highly loaded regions of the bearing surface, thus potentiating increased wear.