J.W.M. Gardeniers

Impacted graft incorporation after cemented acetabular revision. Histological evaluation in 8 patients.

We took core biopsies from the acetabulum in 8 patients (at reoperation) after a previous revision with impacted cancellous allograft chips in combination with cement. Except for one biopsy specimen, the graft showed different stages of incorporation. In the specimens taken at 4 months, revascularization of the graft was found. Osteoclasts had removed parts of the graft, while woven bone had formed on the remnants of the graft and in the stroma that was invading the graft. Subsequent specimens showed that this mixture of graft and new bone was in due time remodeled into a normal trabecular bony structure with viable bone marrow that contained little or no remnants of the original graft. The graft-cement interface was present in 4 biopsies taken at 1, 22, 28, and 72 months. The specimen obtained 28 months after revision showed vital bone locally in direct contact with the cement layer; however, a soft tissue interface predominated.

Particle size of bone graft and method of impaction affect initial stability of cemented cups: human cadaveric and synthetic pelvic specimen studies.

We determined the effect of bone graft particle size and impaction technique on the initial stability of cemented acetabular cups. First, acetabular reconstructions were performed in human cadaveric pelvic bones in which type 2 AAOS cavitary defects were created. Reconstructions were made with small bone grafts (average 2 mm) produced by a bone mill or large bone grafts (average 9 mm) produced by hand with a rongeur. All chips were made from freshly-frozen femoral heads. Impaction was done using acetabular impactors and a hammer. We did a loading experiment with a gradually increasing dynamic load up to 3000 N. We used radiostereometric analysis (RSA) to determine cup stability. The cups were more stable when large bone grafts were used. Because of limitations of the cadaver model, we developed a synthetic acetabular model. For validation of this model, we repeated the experiments using small and large bone grafts. The results with both models were similar. In the synthetic model, we compared impaction with hammer and impactors with the reversed reaming technique using manual compression on the reamer. The latter method resulted in more migration. We recommend firm impaction with a hammer of large bone grafts for optimal stability of the cup.

Acetabular revision with impacted morsellised cancellous bone grafting and a cemented acetabular component: A 20- TO 25-YEAR FOLLOW-UP

We present an update of the clinical and radiological results of 62 consecutive acetabular revisions using impacted morsellised cancellous bone grafts and a cemented acetabular component in 58 patients, at a mean follow-up of 22.2 years (20 to 25). The Kaplan-Meier survivorship for the acetabular component with revision for any reason as the endpoint was 75% at 20 years (95% confidence interval (CI) 62 to 88) when 16 hips were at risk. Excluding two revisions for septic loosening at three and six years, the survivorship at 20 years was 79% (95% CI 67 to 93). With further exclusions of one revision of a well-fixed acetabular component after 12 years during a femoral revision and two after 17 years for wear of the acetabular component, the survivorship for aseptic loosening was 87% at 20 years (95% CI 76 to 97). At the final review 14 of the 16 surviving hips had radiographs available. There was one additional case of radiological loosening and four acetabular reconstructions showed progressive radiolucent lines in one or two zones. Acetabular revision using impacted large morsellised bone chips (0.5 cm to 1 cm in diameter) and a cemented acetabular component remains a reliable technique for reconstruction, even when assessed at more than 20 years after surgery.

Tissue reactions around a hydroxyapatite-coated hip prosthesis: case report of a retrieved specimen

Bone reactions were studied around a titanium, hydroxyapatite (HA)-coated Osteonics (Allendale, NJ) bipolar hip prosthesis, which was revised for severe midthigh pain 4 years after implantation. Inspection of the retrieved prosthesis using a dissecting microscope revealed scarce remnants of a coating-like material on the surface of the prosthesis; however, histology of this layer and histology of the bony side of the bone--HA interface failed to reveal any remnants of an HA coating. The interface was covered predominantly by trabecular bone, which closely followed the contour of the prosthesis, and was partly woven nonmineralized bone. At locations where mineralized bone faced the prosthesis, many small dark titanium wear particles were found. Similar particles were found in macrophages in the intertrabecular medullary space. Polyethylene wear particles were specifically located in macrophages in a soft tissue interface at more distal levels along the stem of the prosthesis. Although the observations presented in this case cannot be generalized, it clearly shows that the HA coating layer had completely disappeared after 4 years. More detailed retrieval studies and longer clinical follow-up studies are needed before a final evaluation of the behavior of HA coatings and long-term fixation of HA-coated prostheses can be made.

Favorable results of acetabular reconstruction with impacted morsellized bone grafts in patients younger than 50 years: A 10- to 18-year follow-up study of 34 cemented total hip arthroplasties

We report a long-term review of 41 acetabular reconstructions using impacted morsellized bone grafts and a cemented total hip arthroplasty (THA) in patients younger than 50 (22-49; average 38) years. Reconstruction was performed in 23 primary THA (19 patients) and 18 revision THA (17 patients). 3 patients were lost to follow-up and 3 (4 hips) died within 10 years of surgery; none had a revision. Thus, 34 hips (30 patients) were reviewed with an average follow-up of 13 (10-18) years. In 2 hips, a revision was performed for aseptic loosening of the acetabular component 7 and 11 years after surgery. One additional cup was revised after 12 years during a femoral stem revision due to wear and matching problems, but was well fixed. The survival rate of the acetabular reconstruction technique was 94% (95% CI: 90-98%).

Femoral neck shortening after internal fixation of a femoral neck fracture.

This study assesses femoral neck shortening and its effect on gait pattern and muscle strength in patients with femoral neck fractures treated with internal fixation. Seventy-six patients from a multicenter randomized controlled trial participated. Patient characteristics and Short Form 12 and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were collected. Femoral neck shortening, gait parameters, and maximum isometric forces of the hip muscles were measured and differences between the fractured and contralateral leg were calculated. Variables of patients with little or no shortening, moderate shortening, and severe shortening were compared using univariate and multivariate analyses. Median femoral neck shortening was 1.1 cm. Subtle changes in gait pattern, reduced gait velocity, and reduced abductor muscle strength were observed. Age, weight, and Pauwels classification were risk factors for femoral neck shortening. Femoral neck shortening decreased gait velocity and seemed to impair gait symmetry and physical functioning. In conclusion, internal fixation of femoral neck fractures results in permanent physical limitations. The relatively young and healthy patients in our study seem capable of compensating. Attention should be paid to femoral neck shortening and proper correction with a heel lift, as inadequate correction may cause physical complaints and influence outcome.

Bone impaction grafting for corticosteroid-associated osteonecrosis of the knee

BACKGROUND Osteonecrosis of the distal portion of the femur produces a segment of dead bone in the weight-bearing portion of the femoral condyle, frequently associated with subchondral fracture and collapse and eventually resulting in secondary osteoarthritis. Treatment of these late stages of osteonecrosis in the knee can be problematic. The purpose of the present study was to evaluate a new surgical technique in which the subchondral osteonecrotic lesion is removed. The bone defect is then reconstructed with impacted bone grafts to prevent collapse and/or to regain distal femoral sphericity. METHODS In this prospective, one-surgeon study, nine consecutive knees in six patients were studied, all of which had extensive corticosteroid-associated osteonecrotic lesions of the femoral condyles. Six knees had collapsed lesions when they were initially treated. The mean age of the patients was thirty-one years. Both the clinical and radiographic outcomes were assessed at a minimal follow-up time of two years. RESULTS At a mean follow-up time of fifty-one months, none of the reconstructed knees had been converted to a total knee prosthesis. The objective Knee Society score improved from a mean of 63 to 89 points. The functional Knee Society score improved from a mean of 19 to 81 points. During the follow-up period, there was no progression of collapse observed; however, three knees showed early signs of osteoarthritis. Clinical success was achieved in six of eight knees, and radiographic success was achieved in seven of nine knees. CONCLUSIONS At the time of writing (at the time of midterm follow-up), this method appears attractive as a joint-preserving procedure. It is a relatively simple procedure that is not likely to interfere with future knee procedures. It appears that this technique can be effective in knees with collapse of the femoral condyle, and it may delay the need for a total knee arthroplasty. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Femoral component revision with use of impaction bone-grafting and a cemented polished stem: a concise follow-up, at fifteen to twenty years, of a previous report.

We previously reported our results for thirty-three consecutive femoral component revisions with impaction bone-grafting, performed with the X-change femoral revision system and a cemented polished Exeter stem, at a minimum of eight years of follow-up. The present updated study shows the results after fifteen to twenty years. One stem was revised again for mechanical reasons during a rerevision of an acetabular cup. The probability of survival at seventeen years was 96% (95% confidence interval [CI], 72% to 99%) with a femoral rerevision for any reason as the end point and 100% (95% one-sided CI, 69% to 100%) with rerevision for aseptic loosening as the end point. The average subsidence was 3 mm and stable relative to our previous report. Although three early femoral fractures occurred after this surgery, in this update no additional fractures were seen. In conclusion, the probability of survival of femoral component revisions with impaction bone-grafting and a cemented polished stem was excellent at a mean of seventeen years.

Clinical and radiological outcome of the cemented Contemporary acetabular component in patients < 50 years of age

Despite the worldwide usage of the cemented Contemporary acetabular component (Stryker), no published data are available regarding its use in patients aged < 50 years. We undertook a mid- to long-term follow-up study, including all consecutive patients aged < 50 years who underwent a primary total hip replacement using the Contemporary acetabular component with the Exeter cemented stem between January 1999 and January 2006. There were 152 hips in 126 patients, 61 men and 65 women, mean age at surgery 37.6 years (16 to 49 yrs). One patient was lost to follow-up. Mean clinical follow-up of all implants was 7.6 years (0.9 to 12.0). All clinical questionnaire scores, including Harris hip score, Oxford hip score and several visual analogue scales, were found to have improved. The eight year survivorship of all acetabular components for the endpoints revision for any reason or revision for aseptic loosening was 94.4% (95% confidence interval (CI) 89.2 to 97.2) and 96.4% (95% CI 91.6 to 98.5), respectively. Radiological follow-up was complete for 146 implants. The eight year survival for the endpoint radiological loosening was 93.1% (95% CI 86.2 to 96.6). Three surviving implants were considered radiologically loose but were asymptomatic. The presence of acetabular osteolysis (n = 17, 11.8%) and radiolucent lines (n = 20, 13.9%) in the 144 surviving cups indicates a need for continued observation in the second decade of follow-up in order to observe their influence on long-term survival. The clinical and radiological data resulting in a ten-year survival rate > 90% in young patients support the use of the Contemporary acetabular component in this specific patient group.

Viability of the acetabular bone bed at revision surgery following cemented primary arthroplasty

Loosening of total hip replacements is often associated with severe loss of periprosthetic bone. The notion exists that the remaining bone is sclerotic, avascular, and displays little osteogenic activity, and that it therefore potentially compromises the revitalization of bone grafts used to restore bony defects. To verify this opinion we studied the bone characteristics in acetabular bone biopsies taken at primary total hip arthroplasty (PTH) and revision total hip arthroplasty (RTH) for a cemented PTH. In 6 PTH patients and in 10 RTH patients, acetabular bone biopsies were taken from the roof, the center, and the lower rim of each acetabulum. Specimens were evaluated by light microscopy and histomorphometrically measured for specimen size, bone area, perimeter, active osteoid perimeter, number of vessels, and osteoclasts. The vascularity and vitality appeared to be comparable in the RTH and PTH bone biopsies. However, the trabecular organization of the RTH bone differed from that of the PTH biopsies. In the PTH biopsies, the trabeculae were running perpendicular to the subchondral bone layer, whereas in the RTH biopsies the layers of bone were oriented parallel to the implant surface. There was abundant remodeling activity in the RTH bone, with large quantities of active osteoid and osteoclasts. These histologic parameters differed, but not statistically significant, from the PTH biopsies. In conclusion, we found that at revision, the acetabular bone was viable with sufficient vascularity and remodeling activity to provide an acceptable recipient host bone bed for revision surgery combined with bone grafting.