High rates of implant fracture of a generic polished tapered femoral stem.

OBJECTIVES: Cemented polished tapered stems have demonstrated excellent long-term outcomes. Based on this concept, many generic tapered stems have been released into the market. The aim of this study was to evaluate implant-related complications of 1 specific stem design. METHODS: Between 2010 and 2017, 315 total hip replacements were performed using a Fortress stem (Biotechni, La Ciotat, France). Patient records and radiology were retrospectively reviewed for implant-related complications. A failure analysis was performed on the failed Fortress stems in order to determine the cause of premature failure. RESULTS: 7 (2.2%) patients sustained a fracture of the neck of the implant after a mean of 5 years (range 50-81 months). All fractures were atraumatic, originating at the introducer inlet of the stem. All fractured occurred in obese patients (BMI >33 kg/m2) with a small sized prosthesis. Of these, there were 5 135° and 2 125° stems. Fracture risk was 23% (7/30) for patients with a small sized stem and a BMI >30 kg/m2. All cases were revised using a cement-in-cement technique or a cementless modular revision stem. Failure analysis on the retrieved stems revealed a stress riser at the bottom of the introducer inlet. CONCLUSIONS: An alarmingly high rate of early implant fractures was seen using this specific type of cemented stem, particularly when using smaller implant sizes in obese patients. Although based on a proven design, a specific modification led to a stress riser in the neck area, which resulted in a high incidence of implant failure. This series underlines the importance of a stepwise introduction into the market of new orthopaedic devices even when based on established concepts. Generic stems may not behave as the original stem upon which it was designed.

Capsular resection versus capsular repair in direct anterior approach for total hip arthroplasty: a randomized controlled trial.

AIMS: Optimal exposure through the direct anterior approach (DAA) for total hip arthroplasty (THA) conducted on a regular operating theatre table is achieved with a standardized capsular releasing sequence in which the anterior capsule can be preserved or resected. We hypothesized that clinical outcomes and implant positioning would not be different in case a capsular sparing (CS) technique would be compared to capsular resection (CR). METHODS: In this prospective trial, 219 hips in 190 patients were randomized to either the CS (n = 104) or CR (n = 115) cohort. In the CS cohort, a medial based anterior flap was created and sutured back in place at the end of the procedure. The anterior capsule was resected in the CR cohort. Primary outcome was defined as the difference in patient-reported outcome measures (PROMs) after one year. PROMs (Harris Hip Score (HHS), Hip disability and Osteoarthritis Outcome Score (HOOS), and Short Form 36 Item Health Survey (SF-36)) were collected preoperatively and one year postoperatively. Radiological parameters were analyzed to assess implant positioning and implant ingrowth. Adverse events were monitored. RESULTS: At one year, there was no difference in HSS (p = 0.728), HOOS (Activity Daily Life, p = 0.347; Pain, p = 0.982; Quality of Life, p = 0.653; Sport, p = 0.994; Symptom, p = 0.459), or SF-36 (p = 0.338). Acetabular component inclination (p = 0.276) and anteversion (p = 0.392) as well as femoral component alignment (p = 0.351) were similar in both groups. There were no dislocations, readmissions, or reoperations in either group. The incidence of psoas tendinitis was six cases in the CS cohort (6%) and six cases in the CR cohort (5%) (p = 0.631). CONCLUSION: No clinical differences were found between resection or preservation of the anterior capsule when performing a primary THA through the DAA on a regular theatre table. In case of limited visibility during the learning curve, it might be advisable to resect a part of the anterior capsule. Cite this article: Bone Joint J 2021;103-B(2):321-328.

Comparison of Constrained Acetabular Components and Dual Mobility Cups in Revision Total Hip Arthroplasty: A Literature Review.

Recurrent instability remains a common cause of failure after revision total hip arthroplasty (THA). Dual mobility (DM) cups and designs with constrained acetabular liners (CAL) have both been developed to help overcome this challenge. The aim of this report is to compare safety and efficacy outcomes of both designs based on the literature. A comprehensive literature review including published evidence on the results of DM and CAL in revision THA was performed and summarized. Available literature focusing on overall survival, dislocation, loosening, intra-prosthetic dislocation (IPD), and functional outcomes were analysed. Forty-six reports including an evaluation of 5,617 total hips were evaluated were included in the review. The included studies were divided into two distinct groups based on implantation approach: i) CAL (n=15) and ii) DM (n=31). The DM group had higher overall survival rates (94.7% vs. 81.0%), lower dislocation rates (2.6% vs. 11.0%), and lower acetabular loosening rates (1.0% vs. 2.0%) compared to the CAL group. IPDs were reported in 6 studies (mean rate, 0.6%). No differences in functional outcomes were identified due to incomplete reports. Our observations reveal that designs with CAL have poorer outcomes as compared to DM cups in revision THA. Currently, the use of DM seems more appropriate since they offer lower rates of dislocations, loosening and re-revisions in the short- and mid-term. Concerns regarding the potential of increased wear in a younger, high-demand population require additional data and evaluation by long-term studies for the DM design.

Safety of Single-Stage Bilateral Versus Unilateral Anterior Total Hip Arthroplasty: A Propensity-Matched Cohort Study.

BACKGROUND: Limited data exist on patient safety after single-stage bilateral and unilateral total hip arthroplasty (THA) through the anterior approach (AA). Therefore, the aim of this study was to compare length of stay (LOS), operative time, 90-day adverse events, 90-day readmission rate, and 1-year revision rate after single-stage bilateral and unilateral THA in matched patients. METHODS: This was a retrospective matched cohort study of prospectively collected data from 2008 to 2018 of a single-surgeon practice. We used the built-in propensity score matching formula in SPSS software and matched bilateral and unilateral patient groups on the relevant covariates of age, sex, and body mass index. This resulted in 60 patients undergoing bilateral THA and 60 patients undergoing unilateral THA. RESULTS: The average LOS was 4.7 days (interquartile range [IQR], 3 to 5 days; range, 2 to 21 days) after bilateral THA and 3.0 days (IQR, 2 to 4 days; range, 1 to 13 days) after unilateral THA (p < 0.001). The mean operative time was 140 minutes for bilateral THA and 69 minutes for unilateral THA (p < 0.001). The adverse event rate was 6.7% after bilateral THA and 5.0% after unilateral THA (p = 0.660). The 90-day readmission rate was 3.3% after bilateral THA and 5.0% after unilateral THA (p = 0.321), which also accounted for all of the revisions within the first year. CONCLUSIONS: When considering single-stage versus staged bilateral AA total hip replacement, patients can expect the same clinical outcome. Because the operative time is longer with bilateral THA, the main advantages are that the patient avoids a second anesthesia session and has an overall shorter recovery time. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Excellent mid-term results of a new polished tapered modular cemented stem: a study of 113 hip replacements with minimum 5-year follow-up.

BACKGROUND: This prospective cohort study reports the medium-term clinical and radiographic results of 113 hips treated with a hybrid total hip replacement (THR) with a new cemented tapered cobalt-chrome (Co-Cr) stem with a titanium (Ti) modular neck (ProfemurXm®). METHOD: Between October 2008 and December 2010 we performed 115 consecutive hybrid THR with the ProfemurXm® in 105 patients. RESULTS: Survivorship of the implant (stem and modular neck) at a mean of 6.5 years (min 5-max 8) was 100% with the endpoint revision for any reason. No implant was at risk for revision or showed signs of loosening. The mean Harris Hip Score was 89/100, mean Oxford Hip Score was 43/48, mean WOMAC was 91/100. No patient had thigh pain, no patient reported squeaking. There were no dislocations in this cohort. No implant showed development of radiolucent lines (RLL), either at the stem-cement or cement-bone interface. No hip showed osteolysis or calcar resorption. The mean femoral subsidence of the stem within the cement mantel was 0.31 mm (range 0-0.6 mm) after 6.5 years. With the use of this modular stem, 93% of hips showed no measurable leg length difference after THR, and leg length could be restored within a 5-mm limit in 99% of hips. CONCLUSIONS: The mid-term results of this new polished stem were excellent, without adverse effects from the use of modularity.

Results of Conserve Plus Hip Resurfacing: prospective clinical, radiographic and ion study.

We report the 3- to 5-year clinical, radiographic and serum ion level results of a prospective consecutive cohort of 42 hip resurfacing arthroplasties using the Conserve Plus implant in 39 male patients that were operated on by a single surgeon in a community hospital. Average age was 53 years (range 34-67) at surgery. There was one revision for a subcapital neck fracture. There were no surgery related complications. The survival of the implant was 95%. Clinical evaluation showed excellent results with a modified Charnley score of 17.6/18, Harris Hip Score of 96.2/100, WOMAC of 95.1/100, Oxford Score 15.3, and UCLA-Activity Score of 8/10. Radiographic analysis showed no implant at risk, no migration or signs of loosening, no neck narrowing and no osteolysis at final follow-up. Average cup inclination angle was 43.5° with 2 outliers (34° and 57°). Ion level study showed average cobalt in serum 1.04 µg/l (range 0-4) for the whole group, 0.7 µg/l (range 0-3) in patients with unilateral resurfacing and 2.0 µg/l (range 0-4) in patients with bilateral resurfacing. All patients had ion levels within the safe zone. This independent series of Conserve Plus HRA confirms good results at short- to mid-term with excellent wear characteristics. Results for avascular necrosis were equal to those for osteoarthritis.