Tom J. J. H. Slooff

Impacted cancellous allografts and cement for revision total hip arthroplasty

We report the results of using impacted cancellous allografts and cement for fixation of the femoral component when revision arthroplasty is required in the face of lost bone stock. In 56 hips reviewed after 18 to 49 months there were few complications and a majority of satisfactory results with evidence of incorporation of the graft. Further study and review are necessary, but the use of the method appears to be justified.

Bone grafting in total hip replacement for acetabular protrusion

Total hip replacement combined with acetabuloplasty was performed in 43 hips in 40 patients with protrusion secondary to arthrosis, rheumatoid arthritis or trauma. Depending on the acetabular defect, the acetabuloplasty encompassed reinforcement of the medial wall with bone grafts, vitallium meshes, protrusio rings and cups. The clinical and radiographic results were uniformly good on average 2 years postoperatively. All grafts appeared to be united and incorporated, without evidence of resorption. The only patient suffering from pain had radiographic signs of progressive varus migration of the femoral component.

Perioperative factors associated with septic arthritis after arthroplasty

Perioperative factors associated with late septic arthritis after knee and hip arthroplasties were prospectively investigated. All patients received a short course of perioperative cefuroxime. After a follow-up of 1 year, septic arthritis was diagnosed in 9/362 patients (2.5 percent) after knee arthroplasty and in 17/2651 patients (0.64 percent) after hip arthroplasty. For the knee, factors associated with septic arthritis after arthroplasty were rheumatoid arthritis, wound infection, an unhealed wound, and a painful, limited knee function at discharge from the hospital. For the hip, corresponding risk factors were diabetes, failed fracture osteosynthesis, a breakdown of sterility during operation, wound infection, postoperative urinary tract infection, and an unhealed wound at discharge from the hospital or a difficult rehabilitation course. Reoperation after knee and hip arthroplasty was also clearly associated with a higher incidence of septic arthritis.

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.

Acetabular reconstruction with impacted morselized cancellous allografts in cemented hip arthroplasty: A histological and biomechanical study on the goat

Bone defects in total hip arthroplasty revision surgery can be restored with different types of bone graft. The use of impacted morselized allograft chips in combination with cement is the treatment of our choice. To establish the incorporation capacity of the grafts and mechanical stability of the implant, an animal model in the goat was developed. An acetabular defect was created and restored with morselized grafts and a cemented cup. Postoperative performance of the reconstruction was followed both histologically and biomechanically. Histology showed that consolidation of the graft with the host bone bed had occurred within 3 weeks. In the following period a front of vascular sprouts infiltrated the graft. Graft resorption, woven bone deposition, and subsequent remodeling resulted in a new trabecular structure. This structure contained only scarce remnants of the original dead graft material. At the graft-cement interface, graft resorption and new bone formation had resulted in areas of direct vital bone-cement contact. Locally, a soft tissue interface was present. After longer follow-up periods, progressive interface formation and loosening of the cups were found in most animals. Mechanical testing showed that the stability of the reconstruction increased during the first 12 postoperative weeks. Thereafter, the stability decreased, probably by soft-tissue interface formation at the graft cement interface. We conclude that cemented morselized allografts have a high capacity to incorporate. Initial cup stability is adequate to provoke graft incorporation with decreasing stability after the incorporation process has been completed.

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.

Interface stresses in the resurfaced hip Finite element analysis of load transmission in the femoral head

The load transmission and interface stresses in the Wagner resurfaced femoral head were evaluated for the purpose of studying possible failure mechanisms. We found that unnatural stress patterns occur in the head and at the implant-bone interfaces, in addition to regions of stress protection in the bone, possibly enhancing interface failure and bone remodelling. However, these stresses are not higher than those reported for other kinds of prostheses, e.g. acetabular cup, tibial plateau. From these findings, together with clinical observations, it is hypothesized that the femoral surface cup is more sensitive to local loosening than other prostheses. This hypothesis would indicate that prosthetic designs should be analysed relative to their potential to provoke failure propagation, rather than only initiation of mechanical failure and loosening.

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%).

Malignant epithelioid hemangioendothelioma at the site of a hip prosthesis

We report a case of malignant epithelioid hemangioendothelioma in the acetabulum and ipsilateral femur 11 years after a total hip prosthesis.