Radiostereometric analysis in hip revision surgery--optimal time for index examination: 6 patients revised with impacted allografts and cement followed weekly for 6 weeks

Similar migration for medial congruent and cruciate-retaining tibial components in an anatomic TKA system: a randomized controlled trial of 60 patients followed with RSA for 2 years

Background and purpose - There is an ongoing debate regarding the appropriate level of constraint in primary TKA. To provide increased stability and better kinematics, more resembling a natural knee, a medial congruent (MC) tibial insert has been introduced. To investigate potential impact on implant migration, we evaluated the cemented Persona TKA, randomizing between MC and cruciate-retaining (CR) tibial designs. Patients and methods - 60 patients with primary osteoarthritis were randomized to either the CR or MC tibial component. Radiostereometric analysis (RSA) examinations, evaluating translational and rotational migration as well as maximal total point motion (MTPM), were performed on the first postoperative day, at 3 months, and 1 and 2 years after surgery. Preoperative, and 1- and 2-year patientreported outcome measures (PROMs) data (KOOS and FJS) were collected. Results - The mean tibial MTPM at 3 months were 0.48 mm (95% CI 0.37-0.58) and 0.56 mm (0.45-0.67) for the CR and MC respectively. 2 years postoperatively the respective values were 0.62 mm (0.50-0.73) and 0.73 mm (0.49-0.96). There was no statistically significant difference in migration between groups, for either the femoral or the tibial component, regarding x-, y-, and z-translations or rotations. Both CR and MC groups improved as expected in PROM scores pre- to postoperatively, but without a statistically significant difference between groups. There were no revisions or other serious adverse events related to surgery. Interpretation - The results are promising, indicating good fixation for both designs, and this is in line with other well-performing TKAs on the market. The increased medial congruity of the MC inlay does not seem to affect the migration or the PROMs up to 2 years.

Highly Porous Tantalum Acetabular Components Without Ancillary Screws Have Similar Migration to Porous Titanium Acetabular Components With Screws at 2 Years: A Randomized Controlled Trial

BACKGROUND

It is proposed that highly porous coatings on acetabular components, such as a porous tantalum coating, provide adequate fixation without ancillary screw fixation in primary total hip arthroplasty (THA). However, tantalum acetabular components have been associated with higher rates of revision than other uncemented components in national registries. The aim of this randomized controlled trial is to determine whether the early migration of a solid-backed tantalum acetabular component was no greater than that of a titanium acetabular component with ancillary screw fixation that has proven good clinical results.

METHODS

Sixty-six patients aged 40 to 64 years, with osteoarthritis and Charnley grade A or B activity grade and who underwent primary THA, were recruited into the trial. Patients were randomized intraoperatively to receive either the tantalum or titanium acetabular component. All patients received the same cemented polished tapered femoral stem, 28-mm cobalt-chromium femoral head, and highly cross-linked polyethylene liner. Acetabular component migration was measured using radiostereometric analysis at 4-6 days postoperatively and at 6 weeks, 3 months, 1 and 2 years following THA.

RESULTS

The mean proximal migration at 2 years for the tantalum cohort was 0.17 mm (95% confidence interval, 0.09-0.24) which was no greater than that of the titanium cohort which was 0.19 mm (0.07-0.32). Harris hip scores and functional activity scores were similar between groups.

CONCLUSION

These results demonstrate that early stability can be achieved without ancillary screw fixation through the use of a highly porous high friction coating on a solid-backed modular acetabular component.

LEVEL OF EVIDENCE

Level I.

Acetabular Component Migration Measured Using Radiostereometric Analysis Following Revision Total Hip Arthroplasty: A Scoping Review

* Radiostereometric analysis (RSA) studies of acetabular component migration following revision total hip arthroplasty (THA) have a large variation in their methodology and reporting of results, and, therefore, they may not be directly comparable. Standardization of RSA reporting is recommended. * In our review of RSA studies, there was a trend for cemented acetabular components to have larger amounts of early proximal migration than uncemented acetabular components. Results regarding cemented and uncemented components should be reported separately. * Cohorts that addressed larger acetabular defects were associated with a larger amount of early migration. * Reporting the migration result at 1 and 2 years postoperatively may enable earlier identification of poorly performing implants.

Adherence of hip and knee arthroplasty studies to RSA standardization guidelines. A systematic review

BACKGROUND AND PURPOSE

Guidelines for standardization of radiostereometry (RSA) of implants were published in 2005 to facilitate comparison of outcomes between various research groups. In this systematic review, we determined how well studies have adhered to these guidelines.

METHODS

We carried out a literature search to identify all articles published between January 2000 and December 2011 that used RSA in the evaluation of hip or knee prosthesis migration. 2 investigators independently evaluated each of the studies for adherence to the 13 individual guideline items. Since some of the 13 points included more than 1 criterion, studies were assessed on whether each point was fully met, partially met, or not met.

RESULTS

153 studies that met our inclusion criteria were identified. 61 of these were published before the guidelines were introduced (2000-2005) and 92 after the guidelines were introduced (2006-2011). The methodological quality of RSA studies clearly improved from 2000 to 2011. None of the studies fully met all 13 guidelines. Nearly half (43) of the studies published after the guidelines demonstrated a high methodological quality and adhered at least partially to 10 of the 13 guidelines, whereas less than one-fifth (11) of the studies published before the guidelines had the same methodological quality. Commonly unaddressed guideline items were related to imaging methodology, determination of precision from double examinations, and also mean error of rigid-body fitting and condition number cutoff levels.

INTERPRETATION

The guidelines have improved methodological reporting in RSA studies, but adherence to these guidelines is still relatively low. There is a need to update and clarify the guidelines for clinical hip and knee arthroplasty RSA studies.

The effect of adding tobramycin to Simplex P cement on femoral stem micromotion as measured by radiostereometric analysis: a 2-year randomized controlled trial

BACKGROUND

Previous in vitro research on addition of antibiotics to bone cement has found no statistically significant deterioration in mechanical properties. However, no clinical studies have compared the performance of tobramycin-laden bone cement with that of standard bone cement (Simplex P).

PATIENTS AND METHODS

23 patients (25 hips) were randomized to receive an Exeter (Stryker Orthopaedics) femoral stem cemented with either Simplex P (standard) or Simplex T (tobramycin-laden) cement. There were 2 years of follow-up, with scheduled radiostereometric (RSA) examinations.

RESULTS

All stems migrated distally and showed some degree of retroversion. No clinically significant differences in stem subsidence or retroversion were found between the Simplex T and Simplex P cement groups after 2 years. Overall subsidence was less than in previous studies, probably due to a postponed initial post-surgical examination. Rates of subsidence in both cement groups were consistent with those from previous studies of Exeter stems.

INTERPRETATION

Subsidence of the femoral stem after 2 years was similar in the Simplex T (tobramycin-laden) and Simplex P (standard) groups.

The optimal timing of baseline radiostereometric analysis of uncemented press fit cups

BACKGROUND AND AIMS

The baseline radiostereometric analysis (RSA) is usually performed during the first postoperative week. We investigated the micromotion of two uncemented press fit acetabular cups during the first week after total hip arthroplasty.

MATERIAL AND METHODS

All study patients had unilateral osteoarthritis of the hip and received an uncemented THA combination consisting of a CLS stem and either an Allofit or an Interop acetabular cup. The study group consisted of 24 patients who underwent RSA within 1 hour after skin closure, and at 1 and 7 days after surgery.

RESULTS

The upper limit of the 95% confidence interval for micromotion was less than or close to the precision of the method for all studied directions during the first week after surgery. Mean values indicate proximal and medial translation of the uncemented cup at one week.

CONCLUSIONS

We found only minimal micromotion, barely above the precision limit, measured as medial and proximal translations of these uncemented cups. This indicates that the first postoperative RSA measurement following a primary THA with an uncemented press fit ace-tabular cup should be made as early as possible after the first postoperative day.

Revision total hip arthroplasty with femoral impaction bone grafting

PURPOSE

To report the radiological and clinical results of revision total hip arthroplasty (THA) with femoral impaction bone grafting (IBG).

METHODS

4 men and 9 women (15 hips) aged 38 to 84 years underwent revision THA with femoral IBG using Elite plus stems for aseptic loosening or infection.

RESULTS

The mean follow-up duration was 7.7 years. The Harris hip score improved from 61.7 to 83.7. There was no pain in 11 hips and slight pain in 4. The mean subsidence was 5.7 mm. The mean change of alignment was 1.2 degrees. There was no radiological evidence of stem loosening. One stem was revised due to a peri-prosthetic fracture. Cortical healing was noted in 11 hips, and trabecular incorporation in 10.

CONCLUSION

Although intra- and post-operative complications were not uncommon, femoral IBG is a safe procedure in carefully selected patients and offers good medium-term results.

Hip revision using the Exeter stem, impacted morselized allograft bone and cementA consecutive 5-year radiostereometric and radiographic study in 15 hips

BACKGROUND

Impaction grafting in hip revision surgery is widely used but studies with mid- and long-term follow-up are scarce.

PATIENTS, METHODS AND RESULTS

A 5-year radiostereometric (RSA) follow-up of 15 hip revisions with the Exeter stem, morselized impacted allograft bone and cement revealed that 3 stems had not migrated between 2 and 5 years after revision, 11 stems had migrated to a minor degree in at least 1 direction, and 1 stem was loose according to RSA but without any radiographic signs of loosening or pain. The pain score was comparable to primary arthroplasties.

INTERPRETATION

From a 5-year perspective, first-time hip revisions for aseptic loosening with impacted morselized allograft bone and cement appear to yield good clinical results, although stem migration continues to a minor degree 2 years after revision.

Cement penetration and primary stability of the femoral component after impaction allografting

This study explored the relationship between the initial stability of the femoral component and penetration of cement into the graft bed following impaction allografting.

Impaction allografting was carried out in human cadaveric femurs. In one group the cement was pressurised conventionally but in the other it was not pressurised. Migration and micromotion of the implant were measured under simulated walking loads. The specimens were then cross-sectioned and penetration of the cement measured.

Around the distal half of the implant we found approximately 70% and 40% of contact of the cement with the endosteum in the pressure and no-pressure groups, respectively. The distal migration/micromotion, and valgus/varus migration were significantly higher in the no-pressure group than in that subjected to pressure. These motion components correlated negatively with the mean area of cement and its contact with the endosteum.

The presence of cement at the endosteum appears to play an important role in the initial stability of the implant following impaction allografting.

Acetabular reconstruction with impacted bone allografts and cemented acetabular components

We reviewed the clinical and radiological results of 131 patients who underwent acetabular revision for aseptic loosening with impacted bone allograft and a cemented acetabular component. The mean follow-up was 51.7 months (24 to 156).

The mean post-operative Merle D’Aubigné and Postel scores were 5.7 points (4 to 6) for pain, 5.2 (3 to 6) for gait and 4.5 (2 to 6) for mobility. Radiological evaluation revealed migration greater than 5 mm in four acetabular components. Radiological failure matched clinical failure. Asymptomatic radiolucent lines were observed in 31 of 426 areas assessed (7%). Further revision was required in six patients (4.5%), this was due to infection in three and mechanical failure in three. The survival rate for the reconstruction was 95.8% (95% confidence interval 92.3 to 99.1) overall, and 98%, excluding revision due to sepsis.

Our study, from an independent centre, has reproduced the results of the originators of the method.

Bone substitution in revision hip replacement

The aim of this retrospective study was to report the preliminary results of femoral peri-prosthetic bone defect reconstruction with a synthetic bone substitute. Twenty-one revisions of the femoral component in 20 patients were evaluated. The mean age at operation was 65.7 years (range, 30 to 79 years). Preoperative femoral deficiencies were rated grade II in 7 cases and grade III in 14 cases according to the SOFCOT classification. None was rated grade IV. Femoral revision was indicated for loosening in 18 hips (including 8 septic cases), femoral osteolysis (1 hip), persistent pain (1 hip) and recurrent dislocation (1 hip). Once the loose prosthesis had been removed, calcium phosphate ceramic (CPC) granules (14 cases) or ceramic granules + cancellous allograft (5 cases) or autograft (2) were firmly impacted in the femoral canal. The stem was standard and always cemented using modern cementing technique. At a mean follow-up of 36 months (range, 14 to 76 months), 90% of the hips were rated good or very good according to the Merle d'Aubigné score. Two diaphyseal femoral fractures occurred and later united. Two hips required re-revision (aseptic loosening; septic recurrence). The absence of radiological osteolysis in 17 cases suggested direct bonding between ceramic granules and bone. Stem subsidence occurred in two cases and was limited (5 and 8 mm). Femoral bone reconstruction using impacted CPC or CPC in conjunction with bone graft in revision hip replacement commonly provided restoration of the bone stock in the short to mid-term. Further long-term studies will be necessary to support this conclusion.

Reconstruction fémorale par céramique de phosphate de calcium macroporeuse impactée au cours des reprises d’arthroplastie de hanche

PURPOSE OF THE STUDY

Management of bone stock loss remains one of the most challenging problems for revision hip surgery. The aim of this retrospective study was to report the preliminary results of peri-prosthetic femoral defect reconstruction with impacted granules of calcium phosphate ceramic.

MATERIAL AND METHODS

Fourteen hips in 13 patients (3 men and 10 women) were evaluated. Age at surgery ranged from 30 to 79 years (mean 66.1 years). All revised devices had been cemented. Femoral revision was indicated for loosening in eleven hips (including six septic cases), femoral osteolysis (one hip), persistent pain (one hip), and recurrent dislocation (one hip). On the preoperative radiological evaluation, bone defects were assessed as SOFCOT grade II in seven case, and grade III in fourteen. None was rated grade IV. Once the loose prosthesis had been removed, bone graft or ceramic granules (14 cases) were firmly impacted in the femoral canal. The stem was standard and always cemented using modern cementing technique.

RESULTS

At a mean follow-up of 34 +/- 15 months (range 14-76 months), eleven of fourteen hips were rated good or very good according to the Postel-Merle-d'Aubigné score. One diaphyseal femoral fracture occurred and later united. Two hips required re-revision (one aseptic femoral loosening, one septic recurrence). Direct bonding between synthetic graft and bone was observed on standard radiographs in eleven cases. Stem subsidence occurred in two cases and was limited (mean 4.5 mm).

DISCUSSION

Femoral bone reconstruction using impacted calcium phosphate ceramic in revision hip arthroplasty provided encouraging results in the short to mid term. Femoral stock restoration was achieved in the great majority. No adverse effect related to the use of a synthetic graft was noted. Further long-term evaluation is required before wider application.

Impaction bone grafting with hydroxyapatite: increased femoral component stability in experiments using Sawbones

BACKGROUND

Substantial bone loss and bone defects increase the amount of allografting required in hip revision surgery. Thus, the use of a synthetic material to limit the amount of allograft tissue required for impaction grafting is desirable. We evaluated the potential of hydroxyapatite (HA) mixtures to provide initial mechanical stability to a polished tapered femoral stem.

MATERIAL AND METHODS

We determined the initial stability of a polished tapered femoral stem after reconstructing a cavitary femoral bone defect by impaction bone grafting with cement in Sawbones composite femurs. Three types of graft material were tested for their ability to improve initial rotational stability. The graft materials investigated were pure allograft, a mixture of 50% allograft and 50% hydroxyapatite (HA), and pure HA.

RESULTS

We found a statistically significant difference between the three groups as regards torsional micromotion and failure load.

INTERPRETATION

Our findings suggest that reconstruction of femoral bone defects with pure HA or a mixture of allograft and HA provides adequate initial stability for femoral revision arthroplasty using impaction grafting.

Guidelines for standardization of radiostereometry (RSA) of implants

There is a need for standardization of radiostereometric (RSA) investigations to facilitate comparison of outcome reported from different research groups. In this document, 6 research centers have agreed upon standards for terminology, description and use of RSA arrangement including radiographic set-up and techniques. Consensus regarding minimum requirements for marker stability and scatter, choice of coordinate systems, and preferred way of describing prosthetic micromotion is of special interest. Some notes on data interpretation are also presented. Validation of RSA should be standardized by preparation of protocols for assessment of accuracy and precision. Practical issues related to loading of the joint by weight bearing or other conditions, follow-up intervals, length of follow-up, radiation dose, and the exclusion of patients due to technical errors are considered. Finally, we present a checklist of standardized output that should be included in any clinical RSA paper.This document will form the basis of a detailed standardization protocol under supervision of ISO and the European Standards Working Group on Joint Replacement Implants (CEN/TC 285/WG4). This protocol will facilitate inclusion of RSA in a standard protocol for implant testing before it is released for general use. Such a protocol-also including other recognized clinical outcome parameters-will reduce the risk of implanting potentially inferior prostheses on a large scale.

Higher failure rate and stem migration of an uncemented femoral component in patients with femoral head osteonecrosis than in patients with osteoarthrosis

BACKGROUND

Several authors have found poorer outcome after hip replacement for osteonecrosis than after hip replacement for arthrosis. In a retrospective study we evaluated the performance of an uncemented femoral component in patients with osteonecrosis and arthrosis of the hip.

PATIENTS AND METHODS

31 patients operated for osteonecrosis, and 49 patients operated for osteoarthrosis were included. The median follow-up time was 6.1 (2-11) years for the patients with osteonecrosis, and 5.9 (4-8) for the arthrosis patients.

RESULTS

Migration analysis performed by the Einzel-Bild-Roentgen Analysis (EBRA) technique revealed a median stem migration of 1.5 (-8.8-0) mm in the patients with osteonecrosis, but only 0.6 (-2.8-0.7) mm in the patients with arthrosis (p < 0.001). Survivorship analysis with stem revision as endpoint for failure was 74% (95% CI: 55-94) in the osteonecrosis, and 98% (95% CI: 94-100) in the arthrosis group (p = 0.01).

INTERPRETATION

We suggest that the higher failure rate and stem migration of uncemented total hip replacement in the patients with osteonecrosis is a consequence of the disease. On the basis of these findings, we recommend close monitoring of the patients with osteonecrosis, which should include migration measurements.

Movement pattern of the Exeter femoral stem; a radiostereometric analysis of 22 primary hip arthroplasties followed for 5 years

BACKGROUND

The design of the Exeter stem may facilitate distal migration, but radiostereometric analysis (RSA) studies have been limited to 2 years of follow-up.

PATIENTS AND METHODS

We followed migration of the Exeter femoral stems in 22 primary hip arthroplasties for 5 years with RSA.

RESULTS

All stems migrated distally and the median migration at 2 years was 1.34 mm, while at 5 years it was 1.77 mm. 7 stems migrated above accuracy between 3 and 5 years. (RSA) evaluation of the cement mantle could be performed in 14 cases, and in 5 slight migration was found. Most of the stems rotated towards retroversion and the median rotation at 2 years was 1.2 degrees, while at 5 years it was 1.6 degrees. We found 1 patient with impending clinical failure but no deviation in the RSA migration pattern, and 1 patient with unstable migration pattern but no clinical symptoms.

INTERPRETATION

We found a greater distal migration of the Exeter stem for longer periods of time than seen with other types of cemented implants.

Impaction allografting for femoral component revision: clinical update

The technique of cancellous impaction allografting with cement aims to reconstitute a bone-deficient proximal femur while also gaining stable fixation of the femoral prosthesis. Some reports of this technique imply it is a system, requiring not just an exacting surgical method, but also a particular implant design, the polished, double-tapered stem. Other series consider it a surgical technique, and have varied the femoral component design, the method of graft delivery, and other elements of the procedure. Our review evaluates the current literature, with the goal of beginning to ascertain whether published results suggest impaction grafting must be considered a system, requiring a particular stem design, or simply another means to achieve femoral reconstruction in the revision setting. The conclusive answer will require randomized, controlled clinical trials to evaluate particular elements of the procedure, and these studies have yet to be done. However, investigators have shown similarly good short-term to intermediate-term results with various femoral stems at numerous centers. Currently, femoral impaction allografting, whether as a system using particular implant designs or as a surgical technique, is an accepted alternative for revision of a failed femoral component, particularly when bone-stock deficiency is present.

Factors associated with excessive migration in bone impaction hip revision surgery: a radiostereometric analysis study

A prospective radiostereometric analysis (RSA) study of 18 patients with cemented revision hip surgery and impaction grafting with an Exeter stem was done with a follow-up of 2 years for all patients. All factors that could influence migration (ie, micromotion) of the stem were analyzed with a repeated measurements analysis of variance. Two groups could be identified: a stable group and a continuous migrating group. Two factors significantly influenced micromotion during the follow-up measurements. The first factor was the Paprosky classification (the bigger the defect, the higher the micromotion). The second factor was cement mantle defects in > or =1 Gruen zones. The migrating hip stems had more Gruen zones with cement mantle defects (45%) compared with the stable prostheses (21%). The effect of the first factor on micromotion was limited and probably clinically less relevant. Because the cement mantle defects found in this study were caused by poor instrumentation, the second factor stresses the importance of good instrumentation, which is essential to make this technically demanding technique effective in creating a stable stem-allograft construct in the defective femoral canal.