Comparison of Bone Remodeling Between an Anatomic Short Stem and a Straight Stem in 1-Stage Bilateral Total Hip Arthroplasty

Background

Femurs of dysplastic hips exhibit specific abnormalities, and use of modular or specially designed components is recommended. An anatomic short stem was previously designed specifically for dysplastic hips using 3-dimensional data acquired from dysplastic patients. To investigate effects of stem geometry on bone remodeling, we undertook a prospective, randomized study of patients who had undergone 1-stage bilateral total hip arthroplasty (THA) with the anatomic short stem on one side and a conventional straight stem on the other.

Results With the Cementless Spotorno Stem in Total Hip Arthroplasty

Increasingly young and active patients are undergoing total hip arthroplasty, making hip prosthesis survival rates an important issue. Cementless total hip arthroplasty provides better prosthesis longevity than does cemented hip arthroplasty, especially in younger patients. Because there is growing support in the literature for tapered geometry in cementless femoral components, we evaluated short-term results for total hip arthroplasty using Cementless Spotorno (CLS) titanium stems. We performed 100 consecutive primary cementless total hip arthroplasties in 87 patients during a 9-year period using CLS stems. Outcome was assessed in terms of survival rate and Harris Hip Score. The stem survival rate was 99%, and the average Harris Hip Score improved from 41 before surgery to 92 at a mean point of 5 years after surgery. Only 1 hip underwent stem revision for a periprosthetic shaft femur fracture caused by high-velocity trauma from a vehicle accident that occurred 6 months after the original surgery. The CLS stems have an excellent survival rate in the short term, especially in younger patients, but long-term studies are required to provide a fuller picture.     

High Survivorship With Cementless Stems and Cortical Strut Allografts for Large Femoral Bone Defects in Revision THA

Background

Numerous studies have investigated the clinical and radiographic results of revision THAs with use of cementless stems and cortical strut allografts. However, to our knowledge, no long-term followup studies have evaluated patients undergoing revision THA with use of cortical strut allografts where the allografts provided the primary stability for extensively coated femoral stems in the presence of extensive femoral diaphyseal bone defects.

Question/purposes

We performed this study to determine (1) validated outcomes scores; (2) radiographic signs of fixation and allograft healing; (3) frequency of complications; and (4) survivorship of the components after use of cortical strut onlay allografts in Types IIIB and IV femoral diaphyseal bone defects.

Methods

Between 1994 and 2003, we performed 140 revision THAs in 130 patients with Paprosky Types IIIB and IV femoral diaphyseal defects. The patients were treated using extensively coated femoral stems and cortical strut allografts because primary axial or rotational stability could not be achieved without grafting. Ten of the patients (10 hips; 7.7%) were lost to followup or died before 10 years; the remaining 120 patients (130 hips) represent the study group in this retrospective study. There were 66 men and 54 women. Their mean age at the time of index surgery was 59 ± 18 years (range, 36–67 years). The primary diagnosis was predominantly osteonecrosis of the femoral head (53%). The most common reason for revision was aseptic loosening (97%), followed by periprosthetic fracture (3%). The mean time from primary to revision THA was 12 years (range, 8–27 years). The mean duration of followup was 16.1 years (range, 12–20 years).

Results

The mean Harris hip score was 39 ± 10 points before revision and improved to 86 ± 14 points at 16 years followup (p = 0.02). The mean preoperative WOMAC score was 62 ± 29 (41–91) points and improved to 22 ± 19 (11–51) points at 16 years followup (p = 0.003). Of the 130 stems, 113 (87%) had bone ingrowth, five (4%) had stable fibrous ingrowth, and 12 (9%) were unstable. All allografts were incorporated. Four hips (3%) had a displaced femoral shaft fracture at the stem tip; four (3%) had a postoperative dislocation; and six (5%) had early postoperative infection. Kaplan-Meier survivorship analysis, with revision or radiographic failure as the endpoint, revealed that the 16-year rate of survival of the components was 91% (95% CI, 0.88%–0.96%).

Conclusion

Supportive cortical strut onlay allografts provided high survivorship beyond 12 years of followup in revision THAs. Future studies might compare this approach with allograft-prosthesis composites, proximal femoral replacement, or modular fluted, tapered stems.

Level of Evidence

Level IV, therapeutic study.     

Long-Term Results (Minimum of 20 Years) of a Pure Proximal-Loading Metaphyseal-Fitting Anatomic Cementless Stem Without Distal Stem Fixation in Hip Arthroplasty

BackgroundThere are no reported results for more than 20 years of a pure proximal-loading anatomic cementless femoral stem without diaphyseal stem fixation. The purpose of this study was to evaluate the long-term (minimum 20 years) clinical results, bone remodeling, revision rate, and survivorship of these implants in patients aged less than 60 years.MethodsWe included 523 patients (657 hips), including 319 men and 204 women. The mean body mass index was 26.7 (range, 23-29 kg/m²). The mean age of patients at index surgery was 55 years (range, 20-59 years). The Harris Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the University of California, Los Angeles activity score were recorded preoperatively and at each follow-up. Mean follow-up was 23.5 years (range, 20-27 years).ResultsThe Harris Hip Score at the final follow-up was a mean 93 points (range, 70-100 points). The Western Ontario and McMaster Universities Osteoarthritis Index and University of California, Los Angeles activity scores at the final follow-up were 16 and 7.6 points, respectively. Five femoral components (0.8%) and 13 acetabular components (2.0%) were revised. All cases in the current series had grade 2 stress shielding; no hips had grade 3 or 4 stress shielding. Kaplan-Meier survivorship of the implants at 23.5 years was 98.0% (95% confidence interval 92%-100%) for the acetabular component and 99.2% (95% confidence interval 93%-100%) for the femoral component.ConclusionA pure proximal-loading metaphyseal-fitting anatomic cementless stem with alumina-on-alumina ceramic bearing couples functioned well, with no osteolysis or mild stress-shielding at an average 23.5-year follow-up.     

A Prospective,Randomized Comparison of the Long-Term Clinical and Radiographic Results of an Ultra-Short vs a Conventional Length Cementless Anatomic Femoral Stem

BackgroundThe purpose of this study is to compare the long-term clinical and radiographic results, survival rates, and complication rates of an ultra-short vs a conventional length cementless anatomic femoral stem.MethodsWe reviewed 759 patients (858 hips) (mean age, 56.3 ± 12.9 y) who had an ultra-short cementless anatomic stem and 759 patients (858 hips) (mean age, 54.8 ± 12.3 y) who had a conventional length cementless anatomic stem. The mean follow-up was 16.5 years (range 14-17) in the ultra-short stem group and 17.5 years (range 17-20) in the conventional stem group.ResultsAt the latest follow-up, there were no significant differences between the 2 groups in terms of the Harris Hip Scores (92 ± 6 vs 91 ± 7 points, P = .173), Western Ontario and McMaster Universities Osteoarthritis scores (12 ± 8 vs 13 ± 7 points, P = .972), University of California Los Angeles activity scores (7.6 vs 7.8 points, P = .841), patient satisfaction scores (7.7 ± 2.3 vs 7.5 ± 2.5 points, P = .981), and survival rates (97.6% vs 96.6%). However, incidence of thigh pain (P = .031) and stress shielding (P = .001) was significantly higher in the conventional length stem group than in the ultra-short anatomic stem group. Complication rates were similar (1.8% vs 2.7%) between the 2 groups.ConclusionAlthough an ultra-short cementless anatomic femoral stem confers equivalent clinical and radiographic outcomes, survival rates, and complication rates to conventional length cementless anatomic stem, the incidence of thigh pain and stress shielding was significantly lower in the ultra-short cementless anatomic stem.Level of EvidenceTherapeutic Level I.     

Revision Total Hip Arthroplasty With a Modular Cementless Femoral Stem

We retrospectively reviewed 123 patients who underwent cementless THA with modular femoral stem designs for revision THA or conversion of failed ORIF and found 75 patients available for analysis. The Harris Hip Score (HHS) improved from 52 ± 14 to 86 ± 11 (P < 0.001). The femoral stem was re-revised in eight patients (11%). The mean time to re-revision was 1.1 years (0.13–2.54). Reasons for re-revision included infection (n = 5, 7%), aseptic loosening (n = 2, 3%) and significant pain (n = 1, 1%). There were no failures of the modular junctions. PC stems had an increased rate of intraoperative fractures (PC 28% vs. STS 9%, P = 0.04). Modular cementless femoral stems provide acceptable mid-term results in revision THA.     

Adaptive Bone Remodeling With New Design of the ABG Stem. Densitometric Study

To establish the pattern of bone remodeling caused by a cementless, anatomic implant, we intend to evaluate the changes in bone mineral density observed after surgery in the Gruen zones. A controlled, prospective study was carried out, in which a group of 37 patients with primary coxarthrosis were densitrometrically analyzed over the 1 year period following the implant of an ANATO stem (Stryker). The patient's healthy hip was taken as the control. Any differences in the remodeling pattern were compared according to age, body mass index, and implant size. Decreases in bone mineral density were observed after 3 months in all of the zones studied. However, this bone mineral density loss was recovered in all zones by the end of the study, except in zone 7 where a decrease of 7.2% in bone mass was observed. In zones 2 and 6, where more loads are transmitted, bone mass preservation, in accordance with Wolff's law, can be seen. No differences were found in the remodeling pattern in relation to age and body mass index. There were also no differences related to stem size except in zones 1 and 7. The ANATO stem achieves an efficient transmission of loads between the stem and the proximal femur, providing enough mechanical loads for bone preservation. It is only in zone 7 where significant bone atrophy can be observed, attributable to the damage that this area suffers during the surgical process and the subsequent stress-shielding caused by the implant design.     

Clinical Performance,Patient Reported Outcome,and Radiological Results of a Short,Tapered, Porous,Proximally Coated Cementless Femoral Stem: Results up to Seven Years of Follow-Up

Background

The primary aim of our study was to assess clinical performance, patient reported outcome and radiological results of cementless primary total hip arthroplasty using Tri-Lock Bone Preservation Stem.

Results of a Tapered Proximally-Coated Primary Cementless Stem for Revision Hip Surgery

Nineteen patients (nineteen hips) who had undergone revision total hip arthroplasties using a proximally-coated primary cementless stem were evaluated to determine if a subset of revision arthroplasty patients could be identified where the use of this stem would be appropriate. Of these 19 revisions, 15 were performed for the second stage treatment of infection. The femoral bone deficiency was classified as Paprosky Type I in 6 hips and Type II in 13 hips. At a mean follow-up of 49 months, aseptic stem survivorship was 95% with one revision due to aseptic stem failure. The mean Harris hip scores had improved from a mean of 44 points pre-operatively to 89 points post-operatively. Intra-operatively, there was one complication which included a peri-prosthetic fracture distal to the stem which was treated with an allograft strut with cerclage wires. The authors believe that in type I or II femoral defects, the use of this specific cementless stem may be beneficial in the setting of a revision total hip arthroplasty.     

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

BackgroundCementless 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.MethodsData 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.ResultsAfter 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.ConclusionsType 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 EvidenceLevel III.     

Seven-year Results of a Tapered, Titanium, Hydroxyapatite-Coated Cementless Femoral Stem in Primary Total Hip Arthroplasty

Background

Aseptic loosening of cemented hip prostheses is recognized as a long-term problem, and especially in males and younger patients. Much energy has been focused on developing new prostheses that are designed for cementless fixation. We evaluated the performance of and periprosthetic bone response to a tapered, titanium, hydroxyapatite (HA)-coated femoral hip prosthesis at a minimum of 7 years of follow-up after treatment with primary total hip arthroplasty.

Methods

Seventy-eight patients and 86 hips were included in the study. There were 35 men and 43 women; the mean age at the time of the operation was 59 years (range, 41 to 81 years). We used a tapered, titanium (Ti6Al4V), HA-coated femoral implant. We evaluated the patients at a minimum of 7 years of follow-up after treatment with primary total hip arthroplasty. Clinical evaluation was performed using the scoring system and the hip scores were assigned according to the level of pain, the functional status and the range of motion. The patients who refused to return, but who did forward X-rays for review after being contacted were questioned by phone about the functional status of their hip. Radiographic follow-up was performed at six weeks, at three, six and twelve months and yearly thereafter. All the available radiographs were collected and assessed for implant stability, subsidence, osseointegration, osteolysis, stress shielding and evidence of periprosthetic lucency.

Results

Eighty-six hips (78 patients) were available for review at follow-up of greater than 7 years. In 11 of the 86 cases, acetabular failure required revision of the acetabular component, but the femoral stem survived and it was available for long-term evaluation. The radiographs were obtained at 7-year follow-up for another 20 hips, but the patients would not come in for the 7-year clinical evaluation. Therefore, a phone interview was conducted to assess any change in the functional status at a minimum of 7 years.

Conclusions

The mechanical fixation of a tapered, titanium, HA-coated femoral implant was excellent in this study. This femoral design provided reliable osseointegration that was durable at a mean of 7 years follow-up.     

Long-Term Results of Cementless Total Hip Arthroplasty for Patients With High Hip Dislocation After Childhood Pyogenic Infection

BackgroundThe purpose of this study is to analyze the 10-year outcomes of cementless, modular total hip arthroplasty (THA) in adult patients who had high dislocation secondary to childhood pyogenic arthritis.MethodsWe retrospectively followed 56 consecutive patients who underwent cementless, modular THA for the late sequelae of childhood septic arthritis of the hip from 2001 to 2011. There were 23 men and 33 women with a mean age of 47 years (24 to 68). Of the 56 hips, 25 were classified as Crowe type III and 31 as type IV. Mean follow-up was 10.7 years.ResultsOne hip with a quiescent period of 23 years had recurrence of infection. Revision surgery was performed in 2 patients because of loosening and breakage of femoral stem and new infection with no correlation with childhood sepsis, respectively. The mean Harris hip scores improved from 44.2 points preoperatively to 87.5 points at final follow-up. Similarly, the Hip dysfunction and Osteoarthritis Outcome Score and hip pain also significantly improved at the latest follow-up. The mean acetabular cup abduction was 40.8° and the mean anteversion 27.8°, respectively. There were 5 cases of transient nerve palsy and 5 cases of intraoperative fracture.ConclusionTHA can reliably restore the abnormal anatomy and provide good results in these young and active patients who had high hip dislocation secondary to childhood pyogenic arthritis with a relatively high incidence of complications. However, these complications can be treated.     

Total Hip Arthroplasty Using a Cylindrical Cementless Stem in Patients With a Small Physique

We performed total hip arthroplasty using an anatomic medullary locking cementless stem for small-physique patients from 1988 to 1995. We conducted a retrospective study of 50 joints in 44 cases, including 40 developmentally dysplastic hips followed for 12 to 20 years (average, 15.1 years). Average height and body weight were 152 cm and 56 kg (5.0 ft and 124 lb), respectively, with an average body mass index of 24.2. Twelve joints (24%) were revised for acetabular-sided failures. Forty-eight stems (96%) showed bone ingrowth fixation, and there were no unstable stems. The simple cylindrical shape of the distal portion of the AML stem was less affected by deformity of the proximal femur of developmental dysplasia of the hip in patients with a small physique, and both clinically and radiologically good results were confirmed at long-term follow-up.     

Periprosthetic Bone Mineral Density Changes After Implantation of a Curved Bone Preserving Hip Stem Compared to a Standard Length Straight Stem: 5-Yr Results of a Prospective,Randomized DXA-Analysis

Introduction: The objective of this prospective, randomized study was to evaluate differences in periprosthetic bone mineral density changes in the proximal femur after implantation of a cementless bone preserving stem (Fitmore) compared to a cementless straight stem (CLS Spotorno). Methodology: Periprosthetic bone mineral density was measured in 140 patients (aged 33–74 yr) before surgery, 7 d, 3, 12, and 60 mo postoperatively, using dual energy X-ray absorptiometry. The 1-yr results have already been published. The results of the first postoperative measurement served as the baseline value. Because of the different length of the 2 implants we used adapted Gruen zones to divide the periprosthetic bone in seven regions of interest with comparable length. Clinical results were recorded using the Western Ontario and McMaster Universities Arthritis Index and the Harris hip score. Results: Clinical findings showed comparable results in both groups at all follow-ups (p > 0.05). A total of 5 yr after surgery, the comparison of periprosthetic bone mineral density changes showed significant differences in regions of interests 3 (CLS ?3.9% vs Fitmore ?0.2%, p < 0.001) and 5 (CLS ?3.6% vs Fitmore ?1.3%, p?=?0.0028) between both implants. Conclusion: Despite the fact that no exclusive proximal load distribution could be observed, proximal periprosthetic bone loss in the proximal femur was less pronounced after implantation of the bone preserving stem than with the straight stem.