Comparison of Patient-Reported Outcome from Neck-Preserving, Short-Stem Arthroplasty and Resurfacing Arthroplasty in Younger Osteoarthritis Patients

Comparison of periprosthetic bone mineral density between two types of short-stems in total hip arthroplasty with a mean follow-up of 4 years

INTRODUCTION

The use of short stems in primary hip arthroplasty has grown considerably in recent years, with a large variety of designs and stabilization methods available. Few studies have directly compared how these designs and fixation modes influence the bone mineral density (BMD) that is said to be better preserved with shorter implants. This led us to carry out a medium-term retrospective comparative study to (1) specify how the design of two different types of short stems influences the periprosthetic BMD, (2) compare the radiological and clinical outcomes of these stems.

HYPOTHESIS

The periprosthetic BMD of a short stem varies based on the implant's design.

MATERIALS AND METHODS

Ninety-three patients underwent total hip arthroplasty (THA) with a short stem between July 2012 and July 2014. Two groups of patients were formed: Vitae™ short stem (Adler Ortho, Milan, France), Optimys™ short stem (Mathys, Bettlach, Switzerland). The Vitae group consisted of 46 patients, while the Optimys group consisted of 47 patients. The mean age was 66 years, and the mean body mass index (BMI) was 26 kg/m². The groups had comparable age, BMI, sex, Harris Hip score and preoperative radiological features. Periprosthetic BMD of the two types of implants was determined between the 1^st and 4th year postoperative using dual-energy x-ray absorptiometry (DEXA) in the Gruen zones. The radiological and clinical outcomes were also determined.

RESULTS

There was a significant decrease in BMD in zone 7(-5.8%±0.1 CI_95%[-0.09; -0.02] (p=0.003)), zone 2 (-4.8% ±0.1 CI_95%[-0.093; -0.003] (p=0.038)) and zone 6 (-11% ±0.2 CI_95%[-0.19; -0.03] (p=0.009)) in the patients with Vitae stems and in zone 2 (-13.7%±0.3 CI_95%[-0.25; -0.03] (p=0.018)) in the patients with Optimys stems. A significant difference in BMD in zone 7 at 1 year (p=0.014) and 4 years (p=0.001) postoperative and in zone 6 (p=0.011) at 4 years postoperative existed between groups, with the Optimys group having higher BMD. There was a significant increase in femoral offset in the Optimys group but not the Vitae group: Δoffset=-0.50 mm±5.2 CI_95%[-2.05; 1.05] (p=0.522) and Δoffset=2.79 mm±4.2 CI_95%[1.21; 4.37] (p=0.001). The Harris Hip score was not significantly different between the two groups at 4 years postoperative (95.3±2.5 [88; 99] vs. 95.2±2.6 [88; 99] (p=0.991)).

DISCUSSION

The design of short stems appears to influence the distribution of loads and the periprosthetic BMD. These stems are associated with very good radiological and clinical results in the medium term. Bone remodeling appears to continue beyond 1 year after the THA procedure.

LEVEL OF EVIDENCE

III; Retrospective case-control study.

Impact of Acetabular Implant Design on Aseptic Failure in Total Hip Arthroplasty

Background

Failure of cementless acetabular osseointegration is rare in total hip arthroplasty. Nevertheless, new fixation surfaces continue to be introduced. Novel implants may lack large diameter, constrained bearings, or dual mobility (DM) bearings to address instability. We compared clinical and radiographic outcomes for acetabular components with differing fixation surfaces and bearing options, focusing on the relationship between fixation surface and osseointegration and the relationship between bearing options and dislocation rate.

Methods

We retrospectively reviewed 463 total hip arthroplasties implanted with 3 different acetabular components between 2012 and 2016. Records were reviewed for demographics, clinical scores, and complications. Radiographs were examined for evidence of acetabular osteointegration. Analysis of variance and chi-square tests were used to compare cohorts.

Results

All cohorts had 100% survivorship free of acetabular fixation failure with no differences in clinical scores. Dislocation occurred in 1.3% of cases (n = 6). Analysis of the “transition” sizes, for which brand determined the maximum bearing diameter, revealed a significantly higher dislocation rate (3/50, 6%) in implants with limited bearing options. All 4 revisions for recurrent dislocation involved well-positioned components that did not accept large diameter, constrained bearings, or DM bearings, resulting in 3 shell revisions to expand bearing options. Femoral revisions were associated with dislocation risk but did not vary between cohorts.

Conclusion

Dislocation was the primary mechanical cause for acetabular revision, while acetabular fixation failure was not encountered. We caution against selecting “new and improved” acetabular components without options for large diameter, constrained bearings, or DM bearings, even when enabling technology makes component positioning reliable.

The experience of an indipendent center with the MINIHIP® femoral stem

The implantation of short femoral stems has significantly increased over the past decade, thanks to their preservation of bone stock, allowing for easier potential revision of components and physiological joint reconstruction. Their main features are metaphyseal fixation and partial retention of the femoral neck which lead to biomechanical advantages and high stability. They also guarantee the preservation of bone stock and insertion through minimally invasive approaches. Fifty-one non-consecutive patients with osteoarthritis or avascular necrosis were treated by two senior surgeons with total hip arthroplasty (THA) with anterior or anterolateral approach between April 2013 and October 2016. Cementless short femoral stem monobloc (Minihip, Corin, Cirencester, UK) was implanted in all patients who were studied retrospectively. Radiographic outcome was analyzed and clinical outcomes were assessed with Harris Hip Score (HHS), Hip handicap and Osteaorthritis Outcome Score (HOOS) and Oxford Hip Score (OHS). Based on radiological results we did not find periprosthetic osteolysis while bone resorption was evaluated in 5 implants which were classified according to Gruen. The MiniHip stem demonstrates adequate metaphyseal grip, excellent implant stability to ensure implant survival.

Long-term results of an anatomically implanted hip arthroplasty with a short stem prosthesis (MiniHipTM)

AIM

To evaluate the clinical and radiological outcome nine and ten years after short-stemmed, bone preserving and anatomical hip arthroplasty with the MiniHip^TM system.

METHODS

In a prospective study, 186 patients underwent hip arthroplasty with a partial neck preserving short stem (MiniHip^TM, Corin). Elderly patients were not excluded from this study, thus the mean age at the time of surgery was 59.3 years (range 32 to 82 years). Surgery and the follow-up assessments were performed at two Centers. Up until now, the mean follow-up was 112.5 ± 8.2 mo. The Oxford Hip Score (OHS) and the Hip Dysfunction Osteoarthritis and Outcome Score (HOOS) was assessed pre- and each year after surgery. The clinical follow-up was accompanied by standardized a.p. and axial radiological examinations. Periprosthetic lucencies, hypertrophies within the Gruen zones one to fourteen were assessed. A subsidence of the stem was investigated according to Morray and heterotopic ossifications were assessed according to Brooker.

RESULTS

The OHS and HOOS improved from 18 ± 3.3 to 46 ± 2.0 and from 30 ± 8.3 to 95 ± 4.6 points, P < 0.001 respectively. There were no differences regarding age, etiology, friction pairings, etc., (P > 0.05). Two stems were revised due to a symptomatic subsidence four and twelve months postoperatively. Thus, the survivorship for aseptic loosening at nine to ten years was 98.66%. Including one stem revision due to a symptomatic exostosis, bursitis and thigh pain as well as one revision because of a septic stem loosening, the overall survival for the stem with revision for any reason was 97.32%. Besides one asymptomatic patient, radiological signs of a proximal stress-shielding, such as bone resorptions within the proximal Gruen zones, were not noticed. Findings suggesting a distal loading, e.g., bony hypertrophies or bone appositions of more than 2 mm, were also not detected.

CONCLUSION

Regarding these first long-term results on the MiniHip^TM, the implant performed exceedingly well with a high rate of survivorship for aseptic loosening. Our radiological results within the Gruen zones support the design rationale of the Minihip to provide a reliable metaphyseal anchoring with the expected proximal, more physiological load transfer. This might minimize or exclude a stress shielding which might be associated with thigh pain, proximal bone loss and an increased risk of aseptic loosening. The MiniHip^TM is a reliable partial-neck retaining prosthesis with good a clinical long-term outcome in younger as well as elderly patients.

Total Hip Arthroplasty by the Direct Anterior Approach Using a Neck-preserving Stem: Safety, efficacy and learning curve

BACKGROUND

The concept of femoral neck preservation in total hip replacement (THR) was introduced in 1993. It is postulated that retaining cortical bone of the femoral neck offers triplanar stability, uniform stress distribution, and accommodates physiological anteversion. However, data on safety, efficacy and learning curve are lacking.

MATERIALS AND METHODS

We prospectively assessed all patients who were operated for a THR with a short neck preserving stem (MiniHip) between 2012 and 2014. The safety and learning curve were assessed by recording operative time; stem size; and adverse events including periprosthetic fracture; paresthesia; and limb length discrepancy (LLD). The cohort was divided into equal groups to assess the learning curve effect, and the cumulative sums (CUSUM) test was performed to monitor intraoperative neck fractures. For assessment of efficacy, Oxford Hip Score (OHS) and Short Form-36 (SF-36) scores were compared preoperatively and postoperatively.

RESULTS

138 patients with median age 62 years (range 35-82 years) were included with a median followup of 42 months (range 30-56 months). The minimum followup was 2.5 years. The OHS, SF-36 (physical and mental component) scores improved by a mean score of 26, 28, and 27 points, respectively. All patients had LLD of <10 mm (1.9 mm ± 1.3). Adverse events included intraoperative neck fracture (n = 6), subsidence (n = 1), periprosthetic fracture (n = 1), paresthesia (n = 12), and trochanteric bursitis (n = 2). After early modification of the technique to use a smaller finishing broach, the CUSUM test demonstrated acceptable intraoperative neck fracture risk. The second surgery group had a reduced risk of intraoperative neck fracture (5/69 vs. 1/69 P = 0.2), reduced operative time (66 vs. 61 min, P = 0.06), and increased stem size (5 vs. 6, P = 0.09) although these differences were not statistically significant.

CONCLUSIONS

The MiniHip stem is safe alternative to standard THR with good functional outcomes but with a learning curve for the surgical technique, implants sizing, and the risk of intraoperative neck fractures.

Periprosthetic bone density changes after MiniHipTM cementless femoral short stem: one-year results of dual-energy X-ray absorptiometry study

Introduction: The purpose of the current study was to investigate the reaction of the femur to the implantation of the MiniHip^TM in terms of: (1) bone density change during one year; (2) correlations between stem length, CCD (caput-collum-diaphyseal), femoral offset, T-value, and bone density; (3) other co-variables that influence the change of bone density.

Patients and methods: MiniHip^TM implant was performed for 62 patients. The age range of the patients who underwent treatment was 25–78 years. Periprothestic bone density was determined within two weeks postoperatively, after three, six, and twelve months utilizing the DEXA scan.

Results: The highest change was observed in the first three months post-implantation, while significant decrease in density was recorded at proximal Gruen zones 1, 2, and 7, and at distal Gruen zone 4. The decrease in density reached a plateau between the third and sixth months after operation. Afterwards, bone density recovered up to the 12th postoperative month. The correlation analysis showed significant difference between Gruen zone 1 and stem size and CCD. The same significant trend was not reached for Gruen zone 7. Femoral offset showed no correlation. Covariance analysis was unable to establish connection of the results with diagnosis, pairings, or gender.

Discussion: MiniHip^TM densitometric results are promising and comparable to good results of the other representatives of the femoral neck partially-sustaining short stem prostheses with a lower proximal bone density reduction. Periprosthetic bone resorption is a multifactorial process where stem size, CCD angle, and patient-specific variables such as T-value have an impact on the periprosthetic bone remodeling. In particular, this applies to Gruen zone 1.