HIP International

This systematic review assessed evidence on outcome (revision rate for all reasons) following hip arthroplasty from its beginning 5 decades ago.

We evaluated all studies from all current hip implants since their market introduction in 1962 regarding “revision rate per 100 observed component years”. Data were compared with arthroplasty registries.

A total of 54 different hip implants were included: for 81% (44 of 54) data is either absent or poor; for 30% (16 of 54) not a single publication could be found. For 52% (28 of 54) less than 100 revisions for all reasons are published in non-registry studies. The remaining 10 implants (19%) comprise 92638 primary implants with 4473 revisions. Control group were the same implants with 111658 primary cases and 3029 revisions from arthroplasty registries. A systematic developer bias as in knee arthroplasty could not be found but several independent authors were found to significantly bias the literature. The overall revision rates per 100 observed component years from non-registry studies (and joint registries) are 0.4 (0.5) for stems, 0.7 (0.7) for cups and 1.4 (2.1) for resurfacing systems.

For 81% of all hip implants assessed limited evidence exists from non-registry studies regarding outcome (revision rate) even 5 decades after market introduction. For the remaining 19% of implants no systematic developer bias could be found but several individual authors significantly biased results of single implants. We therefore ask for a more active publication of new implants.

The aim of this study was to establish preoperative factors associated with a good outcome in the surgical treatment of femoroacetabular impingement.

A prospective study including 253 consecutive patients (280 hips) was carried out. We defined a “good” score as one which had either a 20 point improvement from preoperative to 12 months postoperative follow-up, or a score of over 80 points at 12-month follow-up in either the Non Arthritic Hip Score (NAHS) or Modified Harris Hip Score (MHHS). We analysed 9 potential predictors of 12-month postoperative outcome: patient age, gender, BMI, surgery type (primary/revision), preoperative anxiety level, preoperative labro-chondral damage, operative side, patients belonging to the armed forces and patients being treated under the workers compensation scheme. We used logistic regression (multivariable, adjusted) and, Fisher's exact test and student t test (bivariate, unadjusted) to analyse the data.

A strong association between workers’ compensation status and not achieving a good outcome following arthroscopic surgery for femoroacetabular impingement (odds ratio 3.84, 95% CI, 0.13-0.51, P<0.0001) was found. A negative effect on postoperative outcome was also observed with increased BMI, although this association was modest (odds ratio 1.06, 95% CI, 0.87-0.99 p = 0.03). Patients with a higher preoperative score did better at 12 months than the rest of the cohort.

The data from this study may be useful for both patient and physician to consider when deciding on a suitable treatment in potential surgical candidates suffering from femoroacetabular impingement.

We sought to identify, which patient and radiographic factors at preoperative and 1-year follow up will predict patient symptom relief at mid-term.

A total of 50 hips in 47 patients with symptomatic FAI were included in this retrospective study. We stratified the hips into “success” and “failure” groups based on the change from baseline to mid-term follow up WOMAC pain score (mean follow up of 5.8 years). An attempt was made to identify factors that are predictive of mid-term outcome among preoperative radiographic measures, dGEMRIC index, range of motion and WOMAC score as well as 1-year follow-up range of motion, radiographic measures, and WOMAC pain scores.

At 1-year follow up, the success rate was 72% (36/50) and at mid-term follow the success rate increased to 82% (41/50). There were no significant associations between mid-term pain scores and baseline factors (all p-values ≥0.10). One-year pain score and hip internal rotation was associated with poor mid-term pain scores but only the 1-year pain score was associated with the mid-term success/failure outcome.

We did not identify clear preoperative predictors of mid-term results but patients with poor pain scores and limited hip internal rotation at 1-year follow-up are less likely to do well at mid-term.

The posterior soft tissue repair is 1 of the preventing factors for dislocation after total hip arthroplasty (THA). The aim of our study was to analyse THA patients with posterior soft tissue repair in terms of suture durability, time of suture failure and correlate the changes in leg length and offset postoperatively to suture durability.

A total of 37 consecutive THA patients operated for osteoarthritis were included in the study. The posterior repair included reattaching the piriformis, conjoined tendons and posterior capsule to the greater trochanter through 2, 2 mm drill holes with 2 grasping stitches. A metal indicator wire was stitched into the piriformis tendon at distance of 1 cm from the greater trochanter after the prosthesis had been implanted and the joint reduced. Anteroposterior radiographs were taken immediately after the patients returned from the operating theatre to the intensive care unit, the next day after mobilisation, and at the 5^th day of stay and at 3 months postoperatively.

Out of 37 THA hips, 6 (16%) had failed immediately after surgery, 25 (68%) at the 1^st postoperative day after mobilisation, 2 (5%) at the 5^th postoperative day, and 1 (3%) repairs had failed at 3 months after THA. In the remaining 3 hips no failure occurred.

We conclude that posterior soft tissue repair in THA often fails and suggest that new posterior soft tissue repair methods be developed.

In order to achieve an oncological margin during limb salvage surgery for tumours around the hip, part or the entire hip joint is frequently sacrificed. Hip arthroplasty restores a functional extremity and achieves limb salvage. Currently there is a paucity of data concerning the late complications, long-term survival, and the risks of re-revision following aseptic revision of a total hip arthroplasty (THA) performed following an oncological resection.

We identified 78 patients who underwent aseptic revision of a THA which was performed for an oncological process involving the hip from 1972 to 2006. All patients had a minimum 5 years of follow-up with a mean of 13 years. Outcomes were compared to 1,378 patients undergoing aseptic revision of a THA that was performed for a diagnosis of osteoarthritis.

The mean 5-, 10-, 15-, and 20-year re-revision-free survival for an oncologic process of the hip was 100%, 85%, 69%, and 57%. Within this cohort, younger patients were at an increased risk of revision surgery. There was no difference in survivorship of the revision implant at any of the aforementioned time points between the oncologic and osteoarthritis cohorts. Patients with an oncologic diagnosis had a higher rate of dislocations, component wear, and loosening compared to the osteoarthritis group.

Late complications following revision surgery of THA performed for an oncologic resection are common. The results of this study provide information for counselling patients on implant survivorship and complications following aseptic revision THA after index surgery for an oncologic indication.

Cementless press-fit total hip arthroplasty (THA) with the Accolade stem (Stryker Accolade™ TMZF, Mahwah, New Jersey) has demonstrated variable implant survivorship and outcomes. The purpose of this study was to analyse the: 1) implant survivorship; 2) complications; 3) functional outcomes; 4) overall quality of life; and 5) patient expectations and satisfaction following THA with this particular press-fit stem.

A prospectively collected database of 222 patients who underwent THA at 7 institutions between 2006 and 2009 using the Accolade stem (Stryker Inc. Mahwah, New Jersey) was evaluated. Harris Hip Score (HHS) and SF-12 were used to assess the outcomes at 2- and 5-year follow-up. Kaplan-Meier survivorship was calculated at 5 years of follow-up.

The 5-year aseptic and all-cause survivorship rates were 99.4% (95% CI, 96.3 to 99.9%) and 97.9% (95% CI, 94.6 to 99.2%), respectively. At 2 and 5 years postoperatively, the patients demonstrated a mean HHS of approximately 89 points and 92 points, respectively. The mental and physical components of the SF-12 mean score increased with the physical component having a more marked increase. The mental and physical components of the SF-12 score increased to a mean of 46 and 45 points at 2 and 5 years, respectively. At 2-year follow-up, over 90% of patients were satisfied with their outcome in a majority of areas surveyed.

Our results suggest that the use of this press-fit construct results in tremendous improvements in functional and quality of life outcomes, along with excellent survivorship at short- and mid-term follow-up.

The most widely used method to assess the outcome of total hip arthroplasty (THA) is the Harris Hip Score (HHS). Patients’ expectations about the benefits of hip arthroplasty are increasing and are no longer limited to pain reduction. Patients believe they will be able to do recreational activity and sport after surgery. It is also essential to assess the level of physical activity after arthroplasty insofar as it is associated with early failure of the components. The purpose of this study is to explore correlation of the HHS with physical activity in patients with THA.

This is a cross-sectional study on 47 patients with THA. Correlation of HHS with the results of physical activity obtained objectively using accelerometer worn for a week and subjectively using the IPAQ questionnaire and the UCLA scale.

There was no correlation between the HHS and the activity measured using accelerometers, or with the IPAQ activity questionnaire. The HHS reported moderately significant correlations with the UCLA scale.

The HHS may not be as discriminatory as other instruments at assessing patient activity levels after THA.

Acetabular component loosening is a leading cause for revision after metal-on-metal hip resurfacing arthroplasty (MMHRA). We aimed to identify potential risk factors and determine radiographic signs associated with this mode of failure.

From a series of 1375 hips treated with MMHRA, 21 (20 patients) underwent revision surgery secondary to aseptic loosening of the acetabular component and 6 patients had a radiographically loose acetabular component. A control group of 27 hips (26 patients) was selected among the patients that did not have a revision, and was matched for age, gender, component size and diagnosis.

Mean time to revision in the loosening group was 103.0 months and the mean time of follow-up in the control group was 161.4 months. We found greater activity levels, range of motion scores, and cup abduction angles in the loosening group. The centre-edge (CE) angle of Wiberg was 10° lower in the loosening group compared with the control group. In addition, 11 of the hips from the study group presented a sclerotic halo superior to the cup on the last radiograph vs. none in the control group. There was no difference in the prevalence of postoperative reaming gaps or radiographic signs of neck-cup impingement between the 2 groups.

Risk factors for acetabular loosening included hip dysplasia with low CE angle, and a large cup abduction angle. The patient's level of activity influences the appearance of symptoms and the time to revision. We recommend selecting patients with a sufficient CE angle and properly orienting the cup.

Radiostereometric analysis (RSA) is an accurate and precise measurement tool of migration and rotation of implants. We investigated if early migration measured with RSA can be used to predict the risk of later aseptic loosening in acetabular revision surgery.

A total of 312 patients who underwent acetabular revision surgery were followed by RSA measurements for 2 to 20 years. The endpoint was either re-revision due to aseptic loosening or loosening on last available radiographic examination. Cox regression model was used to evaluate the predictive value of early migration.

A total of 16 acetabular cups were re-revised due to aseptic loosening and 7 unrevised cups were radiographically loose. Every mm of proximal migration 2 years postoperatively increased the risk of aseptic loosening by 37% (hazard ratio (HR) 1.37, 95% confidence interval (CI) 1.18-1.58). Adjusting for differences in base line demographics, bone defects and surgical techniques in a Cox regression model, risk of aseptic loosening with every mm of proximal migration was even higher (HR 1.94, 95% CI 1.34-2.82, p<0.001).

We found a strong relationship between early migration measured by RSA and risk of late aseptic loosening in acetabular revision surgery. Monitoring proximal migration with RSA should be considered as an essential step in quality assessment when new implants and novel techniques are introduced in acetabular revision surgery.

Scyon Orthopaedics AG developed a new mode of cementless fixation of the femoral component that provides immediate and permanent anchorage by monocortical locking screws. The aim of this study was to evaluate the stability of the Scyon total hip replacement (THR) stem in-vivo.

A total of 15 patients, with an average age of 50 years had surgery between 2008 and 2011. Each patient received a Scyon THR. Standard questionnaires were completed at each follow-up visit for evaluation of functional outcomes. RSA, patient reported outcomes, and plain radiographic follow-up were obtained at 6 months, 1 year, 2 years, and 5 years postoperatively.

The median ± standard error (SE) stem subsidence (negative y-translation) was 0.07 ± 0.07 mm at 1 year, 0.05 ± 0.04 mm at 2 years and 0.04 ± 0.13 mm at 5 years. The median ± SE stem rotation (y-rotation) was 0.1 ± 0.21 degrees at 1 year, 0.51 ± 0.31 degrees at 2 years and 0.60 ± 0.37 degrees at 5 years. Plain radiographs showed bone on-growth onto medial aspect of the stem. Median HHS improved from 55 preoperatively to 93 at 1 year and 97 at 5 years. The median UCLA Activity Score improved from 4 preoperatively to 6 at 1 year and 5 years.

RSA results indicate that the Scyon stem with its 5 monocortical locking screws is stable at 5 years. Immediate surgical fixation of the stem and bony on-growth onto the femoral component may ultimately decrease the rate of aseptic stem loosening in these THR patients.

Modular necks in total hip replacement (THR) can be a source of metal ion release. There are no data to date on the level of cobalt and chromium ions in the serum of patients with a cobalt-chrome stem and a titanium modular neck.

Serum ion levels were measured in healthy volunteers with a well-functioning ceramic-on-ceramic THR.

Average cobalt in serum was 1.21 µg/l for unilateral THR and 2.2 µg/l for bilateral THR. No patient had cobalt levels higher than 2.4 µg/l. No patient had measurable chromium levels. There were no differences in cobalt levels for hips with short necks versus hips with long necks.

The hybrid THR Profemur® Xm – Procotyl® L with a titanium modular neck on a cobalt-chrome stem design shows no signs of abnormal toxic ion levels (cobalt or chromium) in a randomly selected group of well-functioning hip patients.