A 10- to 13-year follow-up study of Harris-Galante type prosthesis in total hip arthroplasty

Stem-bone contact patterns of a long straight tapered uncemented stem for primary THA

INTRODUCTION

Despite excellent long-term survival, total hip arthroplasty (THA) can fail due to aseptic loosening, dislocations, sepsis and periprosthetic fractures, all of which remain considerably burdensome. Aseptic loosening is one of the main causes of THA failure, often due to osteolysis, stress shielding and/or lack of primary stability. This study aimed to investigate stem-bone contact patterns of a long straight-tapered uncemented stem following primary THA, and to determine whether these contact patterns are related to preoperative femoral morphology and whether they influence postoperative outcomes.

MATERIALS AND METHODS

The authors reviewed a continuous series of 60 hips (55 patients) that underwent primary THA using the Corail^® stem (DePuy, Leeds, UK). Patients were evaluated pre- and post-operatively using the Japanese Orthopaedic Association (JOA) score. Computed-tomography (CT) scans were performed preoperatively to assess femoral bone morphology, and immediate postoperatively to assess stem-bone contact patterns. Postoperative radiographs were performed to calculate the Engh score. Regression analyses were performed to determine associations of postoperative JOA and Engh score with 27 independent variables.

RESULTS

Forty-nine patients (54 hips) were assessed at 31 ± 8 months, with a JOA score of 92.9 ± 8.1 and an Engh score of 21.2 ± 1.9. Six patients (6 hips) were lost-to-follow-up. There were no revisions and only one complication (recurrent dislocation). Stem-bone contact patterns were associated with preoperative femoral morphology (sagittal CFI [p = 0.006], femoral offset [p = 0.028], and NSA [p = 0.022]), but were not associated with either postoperative JOA or postoperative Engh score.

CONCLUSIONS

The stem-bone contact patterns of a long straight-tapered uncemented stem are related to preoperative femoral morphology, but do not influence short-term postoperative outcomes. Contact patterns were related to preoperative femoral offset, NSA, and sagittal CFI, but not coronal CFI. Surgeons should, therefore, consider sagittal morphology for surgical planning and templating, in addition to the conventional parameters of coronal morphology.

A review of the biologic effects of spine implant debris: Fact from fiction

BACKGROUND

Biologic-reactivity to implant-debris is the primary determinant of long-term clinical performance. The following reviews: 1) the physical aspects of spinal-implant debris and 2) the local and systemic biologic responses to implant debris.

METHODS

Methods included are: 1) gravimetric wear analysis; 2) SEM and LALLS; 3) metal-ion analysis; 4) ELISA, toxicity testing, patch testing; and 5) metal-lymphocyte transformation testing (metal-LTT).

RESULTS

Wear and corrosion of spine-implants produce particles and ions. Particles (0.01-1000 μm) are generally submicron ( <1 µm). Wear rates of metal-on-polymer and metal-on-metal disc arthroplasties are approximately 2-20 and 1 mm(3)/yr, respectively. Metal-on-metal total disc replacement components have significant increases in circulating metal (less than 10-fold that of controls at 4 ppb-Co and 3 ppb-Cr or ng/mL). Debris reactivity is local and systemic. Local inflammation is caused primarily by ingestion of debris by local macrophages, which produce pro-inflammatory cytokines TNFα, IL-1β, IL-6, and PGE2. Systemic responses associated with implant-debris have been limited to hypersensitivity reactions. Elevated amounts of in the liver, spleen, etc of patients with failed TJA have not been associated with remote toxicological or carcinogenic pathology to date. Implant debris are differentially bioreactive. Greater numbers are pro-inflammatory; the smaller-sized debris are more bioreactive by virtue of their greater numbers (dose) for a given amount of implant mass loss (one 100-μm-diameter particle is equivalent in mass to 1 million 1-μm-diameter particles). Elongated particles are pro-inflammatory (ie, aspect ratio of greater than 3). Metal particles are more proinflammatory than polymers, ceteris paribus.

CONCLUSION

Spinal arthroplasty designs have been in use for more than 20 years internationally; therefore, concerns about neuropathology, toxicity, and carcinogenicity are mitigated. Debris-induced inflammation still depends on the individual and the type of debris. The consequence of debris-induced inflammation is continued; vigilance by physicians is recommended monitoring of spinal implants using physical exams and testing of metal content and bioreactivity, as is planning for the likelihood of revision in younger individuals.

Total hip arthroplasty using proximal porous coating stem with distal sleeve: mid-term outcome

PURPOSE

To report mid-term results of total hip arthroplasty (THA) using the Opti-Fix Plus Hip System (Opti-Fix Hip), and to assess the correlations between peri-implant bone changes and the distal medullary occupancy rate.

METHODS

11 men (13 hips) and 53 women (58 hips) aged 24 to 87 (mean, 61) years underwent THA using the Opti-Fix Hip, with a modular stem and a distal sleeve, and were followed up for a mean of 6.5 (range, 4.8-9.6) years. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) hip score. Implant stability, bone changes around the implant, and the occupancy rate of the stem in the medullary space were examined radiologically. Bone changes around the implant were assessed based on the radiological evidence of a pedestal, osteolysis, stress shielding, and radiolucent lines.

RESULTS

The mean JOA score increased significantly after surgery and was maintained at the latest follow-up. Around the acetabular and femoral components respectively, 38 and 58 hips had radiolucent lines, whereas one and 54 hips developed osteolysis. A pedestal appeared in 21 hips and grade-III or higher stress shielding in 30 hips. Two hips showed loosening of the acetabular components, but none in the femoral components. Osteolysis around the stem was frequently observed in hips with poor distal medullary occupancy.

CONCLUSION

Clinical and radiological outcomes of the Opti-Fix Hip were favourable. The low incidence of osteolysis in the distal stem suggests that the proximal circumferential porous coating was effective. Minor osteolysis around the proximal stem was frequently observed, indicating early excessive wear of the polyethylene liner. Its high distal medullary occupancy rate could inhibit stem micromotion and aseptic loosening.

Study of micromotion in modular acetabular components during gait and subluxation: a finite element investigation

Polyethylene wear after total hip arthroplasty may occur as a result of normal gait and as a result of subluxation and relocation with impact. Relocation of a subluxed hip may impart a moment to the cup creating sliding as well as compression at the cup liner interface. The purpose of the current study is to quantify, by a validated finite element model, the forces generated in a hip arthroplasty as a result of subluxation relocation and compare them to the forces generated during normal gait. The micromotion between the liner and acetabular shell was quantified by computing the sliding track and the deformation at several points of the interface. A finite element analysis of polyethylene liner stress and liner/cup micromotion in total hip arthroplasty was performed under two dynamic profiles. The first profile was a gait loading profile simulating the force vectors developed in the hip arthroplasty during normal gait. The second profile is generated during subluxation and subsequent relocation of the femoral head. The forces generated by subluxation relocation of a total hip arthroplasty can exceed those forces generated during normal gait. The induced micromotion at the cup polyethylene interface as a result of subluxation can exceed micromotion as a result of the normal gait cycle. This may play a significant role in the generation of backsided wear. Minimizing joint subluxation by restoring balance to the hip joint after arthroplasty should be explored as a strategy to minimize backsided wear.

Experimental investigations of the insertion and deformation behavior of press-fit and threaded acetabular cups for total hip replacement

BACKGROUND

The deformation behavior of threaded and press-fit acetabular cups in correlation with the applied torques and forces to insert the cups has not been widely investigated. The aim of this experimental study was to analyze the deformation behavior of threaded (BICON-PLUS) and press-fit (EP FIT PLUS and Metal shell) acetabular cup designs during insertion and extraction with regard to the possibility of cup failure.

METHODS

The experiments were carried out using artificial bone and human acetabular bone. The torque needed to insert the threaded cups and the force applied to the press-fit cups was measured. The force and torque were applied manually by a surgeon using common surgical instruments. The strain of the cups was assessed by tangentially and radially applied strain gauges during the insertion process, the implanted state, and extraction. These measurements were used to calculate the change in diameter of the acetabular cups and the strains at the notches of the threaded acetabular cup.

RESULTS

The results showed that maximum strains and applied torques and force occurred during cup insertion. In the case of the threaded cup, an average maximum insertion torque of 114 Nm was measured using bone substitute, whereas only 47 Nm was assessed using human acetabulum. A maximum change in diameter of 8 microm was calculated during the implanted state for the threaded cup. The impact forces for both press-fit cups ranged from approximately 1.0 to 8.9 kN. The change in diameter was 8 microm for the Metal shell and 4 microm for the EP FIT PLUS. In all cases, no permanent cup deformation was detected.

CONCLUSIONS

The observed deformations suggest that implant failure of the analyzed acetabular cups is unlikely during insertion, the implanted state, or extraction under normal conditions.

Minimum 10-year radiographic follow-up of a cementless acetabular component for primary total hip arthroplasty with a bulk autograft

We radiographically investigated 36 hips in 34 patients with osteoarthritis of the hip who had undergone total hip arthroplasty. Their mean age was 59.2 years (range 36-79 years), and the mean follow-up period was 11.2 years (range 10-14 years). The long-term outcome and the chronological changes in the bulk autograft were examined. The acetabular component of the prosthesis was a Lord-type threaded cup with a smooth surface. At follow-up, bone absorption was minor in 17 joints, moderate in 11, and major in 8. The hips with graft coverage of >==20% (group A) had a significantly higher loosening rate than hips with coverage of <<20% (group B) ( P << 0.05). The cup position changed markedly in group A. Our findings indicate that graft coverage should be less than 20% when a bulk graft is used together with a smooth-surfaced cementless cup.