Recently, new metallurgical techniques allowed the creation of 3D metal matrices for cementless acetabular components. Among several different products now available on the market, the Biofoam Dynasty cup (MicroPort Orthopedics® Inc., Arlington, TN, USA) uses an ultraporous Titanium technology but has never been assessed in literature. Coping with this lack of information, our study aims to assess its radiological osteointegration at two years in a primary total hip arthroplasty and compares it to a successful contemporary cementless acetabular cup.

This monocentric retrospective study includes 96 Dynasty Biofoam acetabular components implanted between March 2010 and August 2014 with a minimum 2 years radiographic follow-up. Previous acetabular surgery, any septic issue or re-operation for component malposition were exclusion criteria. They were compared to 96 THA using the Trident PSL matched for age, gender, BMI and follow-up. Presence of radiolucencies and sclerotic lines were described on AP pelvis views using the classification of DeLee and Charnley

There was no statistical difference between the two groups concerning demographics and mean follow-up (p> 0.05). Shell's anteversion was similar but inclination was greater in the biofoam group (p=0.006). 27,17% of the Biofoam shells presented radiolucencies in 2 zones or more and 0% of the Trident shells. 11,96% of Biofoam cups showed radiolucencies in the 3 zones of DeLee comparing to 0% of the Trident cups. There was no statistical difference between the Biofoam group (n=54/96) and the Trident PSL group (n=57/96) in pre-operative functional scores for both WOMAC subscales and SF-12. When evaluating last follow-up PROM's, no significant differences were found comparing the entirety of both groups, 56 Biofoam and 51 Trident PSL. No difference was found either when comparing Biofoam patients with ³ 2 zones of radiolucencies (n=15) to the whole Trident group (n=51).

This study raises concerns about radiologic evidence of osteointegration of the Biofoam acetabular cup. Nevertheless, these radiological findings do not find any clinical correlation considering clinical scores. Thus, it may question the real meaning of these high-rated radiolucencies, which at first sight reflect a poorer osteointegration. The first possible limitation with this study is an overinterpretation of the radiographs. Nevertheless, both observers were blinded regarding the patients groups and clinical outcomes and there was a strong inter-observer reliability. Although both cohorts were matched on their demographics and were similar on the cup anteversion, we noticed a slightly lower abduction angle in the Biofoam population. It could reduce the bone-implant coverage area and hence hinders the bony integration, but this difference was small and both groups remained in the Lewinneck security zone. Furthermore, even if patients were matched on age, gender, BMI and follow-up, other variables can influence early osteointegration (smoke status, osteoporosis) and have not been controlled even though we have no reasons to think their distribution could differ in the 2 groups.

The real clinical meaning of these findings remains unknown but serious concerns are raised about the radiographic osteointegration of the Dynasty Biofoam acetabular components. Concerns are all the more lawful that this implants aim to enhance osteointegration.

The effectiveness of total hip replacement as a surgical intervention has revolutionized the care of degenerative conditions of the hip joint. However, the surgeon is still left with important decisions in regards to how best deliver that care with choice of surgical approach being one of them especially in regards to the short-term clinical outcome. It is however unclear if a particular surgical approach offers a long-term advantage. This study aims to determine the influence of the three main surgical approaches to the hip on patient reported outcomes and quality of life after 5 years post-surgery.

We extracted from our prospective database all the patients who underwent a Total Hip Replacement surgery for osteoarthritis or osteonecrosis between 2008 and 2012 by an anterior, posterior or lateral approach. All the pre-operative and post-operative HOOS (Hip disability and Osteoarthritis Outcome Score) and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores were noted. Analysis of covariance (ANCOVAs) were used to study the relationship between amount of change in HOOS and WOMAC subscales (dependant variables) and approach used, by also including confounding factors of age, gender, ASA (American Society of Anaesthesiologists) score, Charnley score and Body Mass Index. A total of 1895 patients underwent a primary total hip arthroplasty during the considered period. Among them, 367 had pre-operative and ≥5 years post operative PROM scores (19.47%)

The mean follow-up for the study cohort was 5.3 years (range 5 to 7 years) with, 277 at 5 years, 63 at 6 years, and 27 at 7 years. In the posterior approach group we had 138 patients (37.60%), 104 in the lateral approach (28.34%) and 125 in the anterior approach (34.06%). There were no significant differences between the 3 groups concerning the Charnley classification, BMI, Gender, ASA score, side and pre-operative functional scores. We did not observe any significant difference in the amount of change in HOOS and WOMAC subscales between the 3 groups. There were no differences either in the post-operative scores in ultimate value.

Our monocentric observational study shows that these three approaches provide predictable and comparable outcomes on HRQL and PROMs at long-term follow-up both in terms of final outcome but also in percent improvement. This study has several limitations. We excluded patients who underwent revision surgery leaving the unanswered question of how choice of surgical approach could lead to different revision rates, which have an impact on the functional outcomes. Moreover, even if we controlled for the most important confounders by a multivariate analysis model, there is still some involved cofounders, which could potentially lead to a bias such as smoking, socio-economical status or femoral head diameter. But we do not have any reason to think that these parameters could be unequally distributed between the three groups. Finally, our study cohort represents of 19.47% of the complete cohort. The fact that not all patients have PROM's was pre-determined as eight years ago we instituted that only 1 in 5 patients that returned their pre-operative questionnaire would get their PROM's at follow-up. Despite this, our statistical power was sufficient.

Aims

The aim of the current study was to assess the reliability of the Ottawa classification for symptomatic acetabular dysplasia.

Background

Over 35% of surgeons in the United States, and 10% in Canada use the direct anterior approach for primary total hip arthroplasty (THA). Some of the key barriers in its wider adoption are the learning curve and associated increased risk of adverse events. The purpose of this study was to determine the adoption rate as well as 90-day re-admission and adverse event of the anterior approach in a community-based hospital.

Many patients who undergo a total knee arthroplasty (TKA) wish to return to a more active lifestyle. The implant must be able to restore adequate muscle strength and function. However, this may not be a reality for some patients as quadriceps and hamstrings muscle activity may remain impaired following surgery.

The purpose of this study was to compare muscle activity between patients implanted with a medial pivot (MP) or posterior stabilized (PS) implant and controls (CTRL) during ramp walking tasks.

Fifteen patients were assigned to either a MP (n=9) or PS (n=6) TKA operated by the same surgeon. Nine months following surgery, the 15 patients along with nine CTRL patients completed motion and EMG analysis during level, ramp ascent & descent walking tasks.

Wireless EMG electrodes were placed on six muscles: vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), semimembranosus (SM) muscles, gastrocnemius medial head (GM), and gastrocnemius lateral head (GL). Participants completed three trials of each condition.

EMG data were processed for an entire gait cycle of the operated limb in the TKA groups, and for the dominant limb in the CTRL group. The maximum muscle activity achieved with each muscle during the level trial was used to normalize the ramp trials. The onset and offset of each muscle was determined using the approximated generalized likelihood ratio.

Peak muscle activity (PeakLE), total muscle activity (iEMG), and muscle onsets/offsets were determined for each muscle for the ramp ascent and descent trials. Non-parametric Kruskal Wallace tests were used to test for statistical significance between groups with α=0.05.

During the ramp up task, both MP and PS groups had significantly greater PeakLE and iEMG for the hamstring muscles compared to the CTRL, whereas the PS group had significantly greater PeakLE compared with the MP group for the SM muscle.

During the ramp down task, both MP and PS groups had significantly greater PeakLE and iEMG for the SM and GL muscles compared to the CTRL. The PS group also had significantly greater iEMG for the BF and VM muscles compared to the CTRL. The MP group had a significantly earlier offset for the SM muscle compared to the CTRL.

Stability in a cruciate removing TKA is partially controlled by the prosthetic design. During the ramp up task, the TKA groups compensated the tibial anterior translation by activating their hamstrings more and for a longer duration. The MP group required less hamstrings activation than the PS group.

During the ramp down task, TKA patients stiffened their knee in order to stabilize the joint. The quadriceps, hamstrings and GL muscle were activated more and for a longer duration than the CTRL group to protect the tibial posterior translation. The PS group required greater BF and VM iEMG than the MP group.

Even if surgery reduced pain, differences in muscle activity exist between TKA patients and healthy controls. The prosthetic design provides some stability to the knee, and the MP implant required less muscle activation than the PS implant to stabilize the knee joint.