Not all cementless femoral stems are created equal but the results may be comparable

Single Wedge Femoral Stem Designs are Associated With a Higher Risk for Revision After Cementless Primary Total Hip Arthroplasty

BACKGROUND

Cementless total hip arthroplasty (THA) femoral stems are the most commonly selected prostheses in the United States. Optimal stem geometry remains controversial with excellent survivorship reported for many designs. We compared cause-specific stem revision of single-wedge versus double-wedge designs from a multicenter US cohort.

METHODS

Data from an integrated healthcare network's total joint replacement registry were used to conduct a cohort study. Primary elective cementless THAs were identified (2001 to 2018). Implant exposure groups were classified by design geometry using the system proposed by Khanuja et al. Type 1 single-wedge (n = 11,082) and type 2 double-wedge (n = 32,380) designs were compared, and other design types were excluded; the final study cohort comprised 43,462 THAs. Cause-specific multivariable Cox regressions were used to evaluate risk for revision due to infection or aseptic reasons, including loosening, instability, periprosthetic fracture, or other reasons.

RESULTS

After adjustment for covariates, a higher aseptic revision risk was observed for type 1 when compared to type 2 designs (hazard ratio = 1.91, 95% confidence interval = 1.33-2.75). When looking at specific revision reasons, revision for aseptic loosening (hazard ratio = 3.46, 95% confidence interval = 2.24-5.34) was higher for type 1 versus type 2 designs. No differences were found for septic revision, instability, periprosthetic fracture, or revisions for other reasons.

CONCLUSIONS

Type 1 single-wedge designs were found to have a higher risk of revision due to aseptic loosening relative to type 2 double-wedge designs. Femoral stem geometry should be considered when selecting a cementless femoral implant.

LEVEL OF EVIDENCE

Level III.

Outcomes Following Revision for Mechanically Assisted Crevice Corrosion in a Single Femoral Design

BACKGROUND

Mechanically assisted crevice corrosion (MACC) is a described complication following metal-on-polyethylene (MoP) total hip arthroplasty (THA). The literature regarding outcomes following revision for MACC suggests that complication rates are high. The purpose of this investigation is to add to this literature with the largest reported series to date.

METHODS

This is a retrospective cohort study of 552 consecutive patients who underwent 621 MoP primary THAs. We identified patients who subsequently underwent revision THA for a diagnosis of MACC. All patients were implanted with the same implant combination (Accolade I stem/cobalt-chromium low friction ion treatment femoral head). Patient demographic, surgical, and laboratory data were collected. Follow-up was calculated from the revision surgery and Hip Disability and Osteoarthritis Outcome Score Joint Replacement and hip subjective values (HSV) were examined at final follow-up. Descriptive statistics were performed.

RESULTS

The revision rate for MACC was 11.6% and mean time to revision was 6.6 (±2.4) years. Revised patients (n = 69) had a mean preoperative serum cobalt-chromium ratio of 3.5 (±2.4). There were 8 cases of gross trunnion failure. At mean 3.2 (±1.9) years following revision, the overall major complication rate was 11.6% with a 5.8% reoperation rate. At final follow-up, mean Hip Disability and Osteoarthritis Outcome Score Joint Replacement scores were 83.2 (±15.6) and mean hip subjective value was 77.6 (±17.4). Revision resulted in significant increases in both parameters (P < .001).

CONCLUSION

The incidence of MACC in MoP THA is likely higher than previously reported, particularly for certain implant combinations. Revision surgery for MACC can achieve good outcomes but a high clinical suspicion with early detection and revision is likely key to success.

Primary total hip arthroplasty with a fully porous-coated uncemented stem: up to twenty-eight years. Retrospective cohort study

PURPOSE

The use of cementless prosthesis has increased in the last 30 years with the aim of improving the long-term results of total hip arthroplasties in young and active patients. Encouraging results have recently been reported for cementless titanium and cobalt chromium stems. However, there are few studies with long-term follow-up, and the majority have analysed several models of uncemented stems due to their modifications over the years. Therefore, the aim was to assess the long-term survival rate of the Mittelmeier Mark III or Autophor 900-S stem.

METHODS

A retrospective cohort study of both gender patients under 70 years old with at least one implanted Mittelmeier Mark III uncemented stem was performed. Survival rate was defined as the proportion of stems that did not need a surgical revision from any cause. Clinical status was evaluated using the Merle d'Aubigne scale modified by Matta (excellent/good/fair/poor).

RESULTS

Between 1990 and 1999, 73 stems were implanted. The mean (SD) age at surgical time was 49.3 (9.9) years, and the median (range) of follow-up was 22 (1-28) years. The overall survival rate was 93% (68/73, 95%CI: 85-97%). The stem revisions were due to stem breakage (n = 2), to aseptic loosening (n = 2) and to septic loosening (n = 1). Clinical results were: excellent 84%, good 15% and fair 1.5%.

CONCLUSIONS

The Mittelmeier Mark III stem had an excellent survival rate with a stable long-term fixation and excellent clinical outcomes.

Short-term outcomes with the REDAPT monolithic, tapered, fluted, grit-blasted, forged titanium revision femoral stem

AIMS

Although good clinical outcomes have been reported for monolithic tapered, fluted, titanium stems (TFTS), early results showed high rates of subsidence. Advances in stem design may mitigate these concerns. This study reports on the use of a current monolithic TFTS for a variety of indications.

METHODS

A multi-institutional retrospective study of all consecutive total hip arthroplasty (THA) and revision total hip arthroplasty (rTHA) patients who received the monolithic TFTS was conducted. Surgery was performed by eight fellowship-trained arthroplasty surgeons at four institutions. A total of 157 hips in 153 patients at a mean follow-up of 11.6 months (SD7.8) were included. Mean patient age at the time of surgery was 67.4 years (SD 13.3) and mean body mass index (BMI) was 28.9 kg/m² (SD 6.5). Outcomes included intraoperative complications, one-year all-cause re-revisions, and subsidence at postoperative time intervals (two weeks, six weeks, six months, nine months, and one year).

RESULTS

There were eight intraoperative complications (4.9%), six of which were intraoperative fractures; none occurred during stem insertion. Six hips (3.7%) underwent re-revision within one year; only one procedure involved removal of the prosthesis due to infection. Mean total subsidence at latest follow-up was 1.64 mm (SD 2.47). Overall, 17 of 144 stems (11.8%) on which measurements could be performed had >5 mm of subsidence, and 3/144 (2.1%) had >10 mm of subsidence within one year. A univariate regression analysis found that additional subsidence after three months was minimal. A multivariate regression analysis found that subsidence was not significantly associated with periprosthetic fracture as an indication for surgery, the presence of an extended trochanteric osteotomy (ETO), Paprosky classification of femoral bone loss, stem length, or type of procedure performed (i.e. full revision vs conversion/primary).

CONCLUSION

Advances in implant design, improved trials, a range of stem lengths and diameters, and high offset options mitigate concerns of early subsidence and dislocation with monolithic TFTS, making them a valuable option for femoral revision. Cite this article: Bone Joint J 2020;102-B(2):191-197.

Cemented versus uncemented hip implant fixation: Should there be age thresholds?

There is continued debate as to whether cemented or cementless implants should be utilized in particular cases based upon chronological age. This debate has been rekindled in the UK and other countries by directives mandating certain forms of acetabular and femoral component fixation based exclusively on the chronological age of the patient. This editorial focuses on the literature-based arguments to support the use of cementless total hip arthroplasty (THA), while addressing potential concerns surrounding safety and cost-effectiveness. Cite this article: Bone Joint Res. 2019;8(12):604-607.

Long-term outcomes of a dual-mobility cup and cementless triple-taper femoral stem combination in total hip replacement: a multicenter retrospective analysis

BACKGROUND

The separate design concepts of dual-mobility cups and triple-taper femoral stems were developed to improve survivorship following total hip replacement (THR) by reducing instability/dislocation and enabling enhanced fixation. Successful outcomes at over two decades have been reported with earlier-generation devices based on these concepts. The current study aimed to provide the first long-term results with a unique pairing of later-generation dual-mobility cup and triple-taper cementless femoral stem after a decade of use in patients undergoing THR.

METHODS

In this retrospective analysis, records were reviewed for all subjects implanted with this dual-mobility cup/cementless femoral stem combination at three centers between 2002 and 2005. Any subject who had not already had follow-up visit beyond 10 years, was not previously revised, and still living were invited for a single follow-up visit consisting of Merle d'Aubgine Scores, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, and standard radiographs.

RESULTS

There were 244 THRs available for analysis. At a mean follow-up of 11.9 years, the Kaplan-Meier survivorship (endpoint: revision for any reason) was 99.1% (95% CI, 97.6-99.7) for the stem and 95.9% (95% CI, 93.1-97.6) for the cup. Merle d'Aubigne Scores were significantly improved from baseline and WOMAC scores were in the satisfactory range at the final follow-up. Radiographic analysis revealed no cases of stem subsidence, no cases of bone hypertrophy, 1 (0.4%) case of bone atrophy, and 3 (1.2%) cases of osteolysis around the stem. No subjects had radiolucent lines greater than 1 mm in any femoral Gruen zone. Evidence of cup migration was seen in 1 (0.4%) subject and 1 (0.4%) subject had evidence of osteolysis that was seen in Gruen zones I, II, IV, and V.

CONCLUSIONS

This combination of a later-generation dual-mobility cup and cementless triple-taper stem was associated with excellent survivorship and satisfactory functional outcomes at over 10 years follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02648152. Date of registration: January 6, 2016. Retrospectively registered.

The current role of robotics in total hip arthroplasty

Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA.

Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA.

Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA.

Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.

Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness.

Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088

Cementing of the hip arthroplasty stem increases load-to-failure force: a cadaveric study

Background and purpose - To date, there is not a single clinical or mechanical study directly comparing a cemented and a cementless version of the same stem. We investigated the load-to-failure force of a cementless and a cemented version of a double tapered stem. Material and methods - 10 femurs from 5 human cadaveric specimens, mean age 74 years (68-79) were extracted. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography. None of the specimens had a compromised quality (average T value 0.0, -1.0 to 1.4). Each specimen from a pair randomly received a cemented or a cementless version of the same stem. A material testing machine was used for lateral load-to-failure test of up to a maximal load of 5.0 kN. Results - Average load-to-failure of the cemented stem was 2.8 kN (2.3-3.2) and 2.2 kN (1.8-2.8) for the cementless stem (p = 0.002). The cemented version of the stem sustained a higher load than its cementless counterpart in all cases. Failure force was not statistically significantly correlated to BMD (p = 0.07). Interpretation - Implanting a cemented version of the stem increases the load-to-failure force by 25%.

Long term survival analysis of cementless Spotorno femoral stem in young patients

Objective

The aim of this study was to analyze the survivorship and clinical outcome of Cementless Spotorno (CLS) stem in young patients.

Methods

A total of 99 consecutive hip arthroplasties using CLS stem were performed on 84 patients younger than 50 years of age between 1993 and 2001. 63 patients were available for final follow-up (mean age: 39 ± 7.8 (range: 22–50)). Patients' Harris Hip Scores (HHS) and survivorship estimates were calculated. Radiographs were analyzed for acetabular implant status, canal fill index (CFI), stem alignment, osteolysis, and stress shielding.

Results

Mean follow-up time was 18 years (13–3), and mean HHS was 88.7 (58–100). Patients with femoral neck fracture had a more favorable functional outcome (p = 0.027), while those with stems in varus had lower scores (p = 0.017). 31 stems (49%) were undersized and 30 hips (47%) had perifemoral osteolysis. Acetabular impairment was strongly associated with osteolysis in Gruen zones 1 and 7 (p < 0.01). Seventeen of the osteolytic lesions occurred in Gruen zone 1, 4 lesions in zone 2, 9 in zone 6 and 22 in zone 7. Forty nine stems were well aligned, 10 were in varus and 5 in valgus. Six patients presented with grade 1 stress shielding, 42 with grade 2, 9 with grade 3 and 7 with grade 4. Pedestal formation was evident in 13 cases. Kaplan-Meier survivorship estimates at 18 years with revision for any reason as the end point and with septic revisions excluded were 91.2% (95% CI: 83.7%–98.7%) and 95.1% (95% CI: 89.5%–100%), respectively. There was no difference between survival estimates of patients with different etiologies.

Conclusion

CLS stems in young patients have high survival estimates in the long term with good-excellent results. Spotorno stems perform equally well in all etiologies with no difference in terms of survivorship.

Level of Evidence

Level IV Therapeutic study.