Assessment of fixation in cementless femoral revision of total hip arthroplasty: comparison of the Engh score versus radiolucent line measurement

Osseointegration of a hydroxyapatite-coated stem in femoral neck fractures in the over-80 s

PURPOSE

In the over-80 s, femoral bone is often osteoporotic and unlikely to be conducive to periprosthetic bone rehabitation. This observation often leads to cemented fixation for hemiarthroplasty in femoral neck fracture. Hydroxyapatite is a bioactive coating that has already demonstrated its osteoinductive properties. Our hypothesis is that hydroxyapatite enables prosthetic osseointegration in patients over 80, as well as periprosthetic cortical thickening. The objective was to evaluate the osseointegration of a hydroxyapatite-coated femoral stem in femoral neck fractures in the over-80 s, and the evaluation of the periprosthetic bone regeneration permitted by hydroxyapatite.

METHODS

This was a retrospective study. Osseointegration and periprosthetic bone regeneration were assessed on pre-operative, immediate post-operative and last follow-up radiographs with Engh score, O-SS score, cortical index, Canal Bone Ration (CBR) and Canal Fill Ratio (CFR).

RESULTS

One hundred and forty-six patients were included. At last follow-up, 99.3% (n = 145) of stems were osseointegrated. The mean Engh score was 19.9 [SD 3.1]. The mean O-SS score was 19.1 [SD 2.4], corresponding to very good osseointegration. The mean CBR at last follow-up was 0.48 [SD 0.07], corresponding to a non-osteoporotic femur. There was a significant difference with pre-operative CBR (p < 0,001). The pre-operative cortical index and the index at the last follow-up were significantly different for all levels of measurement (p < 0,001). The CFR at last follow-up was also significantly different with the post-operative CFR (p < 0,001).

CONCLUSION

This study shows the value of using a hydroxyapatite-coated stem on senile, osteoporotic bone to improve cortical thickness along the entire length of femoral bone.

Influence of avascular necrosis of the femoral head on hip prosthesis integration: a radiological analysis

BACKGROUND

Avascular osteonecrosis of the femoral head (AVN) often results in total hip arthroplasty (THA). The cause for increased THA revision rates among patients with AVN is not yet fully understood.

PURPOSE

To perform a comparative radiological analysis of implant integration between patients with AVN and osteoarthritis (OA).

MATERIAL AND METHODS

After a matched pair analysis of 58 patients, 30 received THA due to OA, 28 due to AVN. X-ray images were evaluated after one week ("baseline") and on average 37.58 months postoperatively ("endline"). The prosthesis was grouped into 10 regions of interest (ROI): seven femoral and three acetabular. Incidence, width, and extent of "radiolucent lines" were measured within each zone.

RESULTS

Between baseline and endline, width and extent progressed more noticeably in all femoral and acetabular zones among patients with AVN. In femoral ROI 1, the width increased in 40% of AVN cases compared to 6.7% of OA cases. For acetabular ROI 3, the width increased in 26.7% of AVN cases compared to no perceived changes in the OA group. No signs of prosthetic loosening were found in the AVN group.

CONCLUSION

The increase of width and extent of radiolucent lines over time in patients with AVN could be a sign of lack of osteointegration. However, prosthetic loosening in absence of clinical symptoms cannot be deduced from radiological findings after medium-term postoperative follow-up. Further long-term studies are required to monitor how radiolucent lines develop in respect to long-term implant loosening. Dependent on bone quality, individually adapted reaming and broaching of the implant site are recommended.

Imaging in Hip Arthroplasty Management Part 2: Postoperative Diagnostic Imaging Strategy

Hip arthroplasty (HA) is a frequently used procedure with high success rates, but 7% to 27% of the patients complain of persistent postsurgical pain 1 to 4 years post-operation. HA complications depend on the post-operative delay, the type of material used, the patient’s characteristics, and the surgical approach. Radiographs are still the first imaging modality used for routine follow-up, in asymptomatic and painful cases. CT and MRI used to suffer from metallic artifacts but are nowadays central in HA complications diagnosis, both having their advantages and drawbacks. Additionally, there is no consensus on the optimal imaging workup for HA complication diagnosis, which may have an impact on patient management. After a brief reminder about the different types of prostheses, this article reviews their normal and pathologic appearance, according to each imaging modality, keeping in mind that few abnormalities might be present, not anyone requiring treatment, depending on the clinical scenario. A diagnostic imaging workup is also discussed, to aid the therapist in his imaging studies prescription and the radiologist in their practical aspects.

Differences between proximal bone remodeling in femoral revisions for aseptic loosening and periprosthetic fractures using the Wagner SL stem

Background

Monoblock taper fluted stems have been reliably used to treat proximal femoral periprosthetic fractures (PFF) and femoral aseptic loosening (AL). Although proximal femoral remodeling has been observed around the Wagner Self-Locking (SL) stem, the exact characteristics of this process are yet to be established. Our aim was to compare the remodeling that takes place after femoral revisions for PFF and AL.

Methods

Consecutive patients between January 2015 and December 2017 undergoing femoral revision using the Wagner SL stem for PFF or AL without an extended trochanteric osteotomy (ETO) or bone grafting were selected from our database. Radiological follow-up was performed using plain antero-posterior hip radiographs taken postoperatively and at 3, 6, 12 months and at 24 months. The Global Radiological Score (GRxS) was utilized by four blinded observers. Intra and interobserver variability was calculated. Secondary outcome measures included the Oxford Hip Score and the Visual Analog Scale for pain.

Results

We identified 20 patients from our database, 10 PFF and 10 AL cases. The severity of AL was Paprosky 2 in 2 cases, Paprosky 3A in 2 cases and Paprosky 3B in 6. PFF were classified as Vancouver B2 in 7 cases and Vancouver B3 in 3 cases. Patients undergoing femoral revision for PFF regained 89% (GRxS: 17.7/20) of their bone stock by 6 months, whilst patients with AL, required almost 2 years to achieve similar reconstitution of proximal femoral bony architecture 86% (GRxS: 17.1/20). Inter-observer reproducibility for numerical GRxS values showed a “good” correlation with 0.68, whilst the intra-observer agreement was “very good” with 0.89. Except immediate after the revision, we found a significant difference between the GRxS results of the two groups at each timepoint with pair-wise comparisons. Functional results were similar in the two groups. We were not able to show a correlation between GRxS and functional results.

Conclusions

Proximal femoral bone stock reconstitutes much quicker around PFF, than in the cases of AL, where revision is performed without an ETO. The accuracy of GRxS measurements on plain radiographs showed good reproducibility, making it suitable for everyday use in a revision arthroplasty practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04062-6.

15-year follow-up of MoM 36-mm THA: clinical, laboratory, and radiological (CT and MRI) prospective assessment

INTRODUCTION

There is limited knowledge of the long-term results of metal-on-metal total hip arthroplasty (MoM THA), particularly concerning adverse local tissue reaction (ALTR), Co/Cr ions level and revision rate. Even if MoM bearing surfaces are no longer used, long-term data could help in defining the course and best management for these patients. The purpose of this study is to investigate the clinical outcomes, describe radiological findings including CT metal artefact reduction algorithm for orthopaedic implants (O-MAR) and MRI multi acquisition variable resonance image combination (MAVRIC) in 36-mm MoM THA.

METHODS

In this long-term prospective study, 46 consecutive patients with primary MoM THA (mono- or bilateral) were enrolled between 2004 and 2005. Pinnacle acetabular cup, Summit cementless stem with 36-mm metal head and Ultamet CoCr alloy liner (Depuy Inc.) were implanted, in the same centre by the same senior surgeon. Patients were reviewed at 5-, 10- and 15-years, including Co/Cr levels and standard radiographs at every follow-up, whilst the 15-year follow-up included hip sonography, MRI MAVRIC and CT O-MAR.

RESULTS

At 15 years, the overall survival rate of the implants (both stems and cups) was 83% (30/36). Revisions were performed in 9% (4/46) because of ALTR, 2% (1/46) septic loosening and 2% periprosthetic fracture. Both Cr and Co concentration increased over time, even though remaining at low level risk at 15 years: Co from 0.11 (+/- 0.18) to 4.29 (+/- 3.26) and Cr from 0.38 (+/- 0.32) to 1.37 (+/- 1.15). Functional scores in non-revised patients showed good to excellent results in more than 90%. Engh-score correlated with time from surgery (p = 0.017) and with sonographic, CT and RM findings (p < 0.05). Concordance has been found between CT and MRI findings (sign-rank test, p = 0.241; Intraclass Correlation Coefficients 0.987); however, no specific MRI or CT lesion patterns could be recognised among symptomatic and non-symptomatic patients.

DISCUSSION

The long-term rate of ALTR after 36-mm MoM THA was comparable with previous studies; a regular follow-up for those implants is mandatory. During follow-up Co-Cr levels increased over time and radiography was a suitable screening technique; the Engh score in particular, proved to be a reliable assessment tool. CT O-MAR and MRI with MAVRIC protocols may add valuable data in clinical practice, although MRI is significantly more efficient than CT in the identification of ALTR lesions, peri-articular effusion and in the evaluation of soft tissues.

Cementless revision femoral stems application of press-fit principles and clinical outcomes

BACKGROUND

Cementless femoral stems are currently used in revision total hip arthroplasty (THA) with the surgeon choosing between various fixation modes. The outcomes are good in the medium term; however, some failures have been attributed to technical errors during implantation. When the decision has been made to use a press-fit implant, the impact of the surgeon's technique on the functional outcomes have not been explored in-depth. This led us to carry out a retrospective study on a large population of total hip arthroplasty patients which aims were achieved press-fit to (1) determine the impact of the type of primary fixation (with and without press-fit) on the functional outcomes; (2) specify the effect of stem length on the functional scores when diaphyseal press-fit is achieved and (3) analyse the main reasons why a true press-fit effect was not achieved (three-point fixation).

HYPOTHESIS

There is a relationship between the primary fixation method by press-fit of a revision femoral stem and the functional outcomes.

PATIENTS AND METHODS

We performed a retrospective analysis of a continuous cohort of 244 THA revision cases with a mean follow-up of 6.1 ± 3.5 years (range, 2-18). The femoral area in which close contact was achieved (shared interface between the bone and implant) was used to define various types of press-fit fixation. The functional outcomes were determined using the Harris Hip Score (HHS) and the Merle d'AubignéPostel score (MAP score) out of 12 points (pain and walking items).

RESULTS

The post-operative HHS averaged 90.83 ± 7.51 for proximal press-fit and 80.14 ± 14.93 with no press-fit (p = 0.01). The MAP averaged 10.83 ± 1.03 for proximal press-fit and 9.75 ± 2.09 with no press-fit (p = 0.09). The MAP score was worse for long diaphyseal press-fit than for short press-fit (p = 0.02). Use of a long stem with an endofemoral route or an overly small femoral window in patients with a curved femur is the main reason that three-point fixation occurred instead of press-fit.

CONCLUSIONS

While press-fit is an effective concept, it is a demanding one that requires the surgeon to choose the correct surgical strategy for the patient's anatomy. A meticulous surgical technique is required to achieve proximal press-fit or at a minimum, short diaphyseal press-fit.

Mid-term results of revision total hip arthroplasty with an uncemented modular femoral component

INTRODUCTION

During revision total hip arthroplasty (THA), the surgeon commonly faces deficient proximal femoral bone. In this situation, distal fixation of the prosthesis is required. The aim of the current retrospective study is to assess the clinical and radiographic mid-term outcome of revision total hip arthroplasty using a modular uncemented, tapered, grit-blasted, distal straight stem system.

METHODS

This retrospective study included 70 femoral revisions that were performed in 67 patients using the device of interest. All patients were operated on via an extended trochanteric osteotomy. 60 revisions were performed as 1-stage (12 infected) and 10 as 2-stage (all infected) revisions. At 3 months postoperatively and at final follow-up, patients were assessed radiographically for the presence of osteolysis and for distal integration.

RESULTS

The mean follow-up time was 4.3 (2.0-7.6) years. 4 patients had a removal of at least 1 prosthetic component. Stem survival for any reason was 92% after 5 years (95% confidence interval [CI], 83%-100%). With aseptic loosening of the stem as the endpoint of interest, survival after 5 years was 96% (95% CI, 88%-100%). A postoperative subsidence rate of 14.7% was found. No perioperative femoral fractures were found in the current patient series.

CONCLUSIONS

This study showed excellent mid-term survival and good clinical and radiographic outcomes in patients who had undergone revision THA with a modular uncemented, tapered, straight design.

Global radiological score for femoral cementless revision stem

PURPOSE

The purpose of this study was to evaluate the outcomes of total hip arthroplasty (THA) revision with cementless stems using a numeric global radiological score (GRxS) that summarizes two previously validated scores: secondary bone stock (SBS) and osseointegration-secondary stability (O-SS).

METHOD

One hundred fifty cases of THA were evaluated at a mean follow-up of 6.5 ± 3.7 years. The GRxS combines the SBS, which evaluated cortical bone thickness, bone density and bone defects in each Gruen zone and the O-SS, which evaluated the location and extent of a single radiolucent line. To calculate the GRxS, the SBS and O-SS were each expressed on a 10-point scale and given equal weighing. The final result was a number out of 20. The GRxS was used to assign a radiological grade to each THA case: very good (20), good (18-15), average (13-12), or poor (≤ 10). The numerical mean (Nm) was calculated for each grade. The inter- and intra-observer reproducibility was evaluated.

RESULTS

The inter-observer reproducibility was good (0.8) and the intra-observer reproducibility was very good (0.9). The GRxS was considered very good in 46 cases (Nm 20), good in 57 cases (Nm 16.6), average in 25 cases and poor in 22 cases. There was a significant relationship between the GRxS and the Harris Hip and Postel Merle d'Aubigné scores (p < 0.0001), and the initial bone stock (p = 0.0001).

CONCLUSIONS

The GRxS is reliable and reproducible. This information can be used by surgeons to adapt the surgical technique to bone characteristics (especially during revision cases) and to compare the outcomes of different implant designs.

Global fit concept in revision hip arthroplasty for cementless press-fit femoral stems

A revision stem may be required after a femoral extended trochanteric osteotomy (ETO) is made during revision hip arthroplasty. The two main complications of straight cementless femoral stems are subsidence due to inadequate osteointegration and stress-shielding. We will describe an original revision method with ETO that uses a straight cementless stem. The goal of this method was to achieve the most extensive press-fit possible during stem implantation to improve the transmission of stresses to the bone and to prevent reduction in bone density. The intramedullary preparation was done after closure and fixation of the ETO, which allows impaction of the revision stem with metaphyseal and diaphyseal press-fit. We report encouraging results with preservation of periprosthetic bone stock and good osteointegration of these revision stems at the final follow-up. Pronounced sagittal curvature or large bone defects are contraindications for this technique.

Femoral revision surgery using a fully hydroxyapatite-coated stem: a cohort study of twenty two to twenty seven years

PURPOSE

Femoral component revision with either cemented or proximally coated stems has been disappointing, but revision with extensively coated stems has been promising. Our purpose was to evaluate the long-term outcome using an extensively hydroxyapatite (HA)-coated stem in femoral revisions surgery.

METHODS

During 1988-1993 we performed 66 femoral revisions in 65 patients (49 women), mean age 58 (range, 28-86) years. We used a grit-blasted straight stem made of TiAl₆V₄ designed for press-fit insertion (Landos Corail; Landanger, Chaumont, France). In 48 hips we used primary stems of size 10 in two cases, size 11 in two, size 12 in seven, size 13 in four, size 14 in 12, size 15 in eight, size 16 in 12 and size 18 in one. In 18 cases, we used revision stems of size 12 in four cases, size 14 in seven, size 16 in five and size 18 in two.

RESULTS

During follow-up, 21 patients have died. One patient had a traumatic fracture around the stem after six years, and another patient with osteoporosis developed fatigue fracture of the femoral bone after 22 years. In one patient the cup loosened after 23 years. The cup was revised, but deep infection occurred, and the patient underwent a two-stage revision of both components. Then, 12 of the revised stems were followed for more than ten years and 24 for more than 20 years. During this time only one stem was revised due to mechanical failure. This patient had a femoral defect classified to Type IV, and a proximal fracture occurred when the prosthesis was inserted. The fracture was stabilised by wires, but primary stability of the stem could not be obtained. At control examinations no patients suffered from significant thigh pain, and we noticed a low degree of proximal bone loss and a low incidence of distal bone hypertrophy.

CONCLUSIONS

Our study suggests that a fully HA-coated stem in femoral revision surgery can provide reliable results for up to 27 years. The bone changes confirmed a well-fixed femoral component with a rather physiological transfer of stress from proximal to distal regions with no significant thigh pain.