Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity.

INTRODUCTION: Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating. HYPOTHESIS: Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants. MATERIAL AND METHODS: A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation. RESULTS: Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%. DISCUSSION: There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation. LEVEL OF EVIDENCE: IV; retrospective study.

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 1st 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 CI95%[-0.09; -0.02] (p=0.003)), zone 2 (-4.8% ±0.1 CI95%[-0.093; -0.003] (p=0.038)) and zone 6 (-11% ±0.2 CI95%[-0.19; -0.03] (p=0.009)) in the patients with Vitae stems and in zone 2 (-13.7%±0.3 CI95%[-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 CI95%[-2.05; 1.05] (p=0.522) and Δoffset=2.79 mm±4.2 CI95%[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.

Femoral stem modularity.

Femoral stem modularity in hip replacement was first developed to connect a ceramic head to the stem, then extended to metal heads using the Morse taper principle. Is it a good thing, or a necessary evil? It contributes to improving lower limb length and lateralization setting, at the cost of fairly rare complications such as dissociation and fretting corrosion, which can exceptionally lead to ARMD (Adverse Reaction to Metal Debris). Modular necks were later recommended, with a double Morse taper: cylindrical for the head junction, and more or less flattened for the stem. Is this one modularity too far? Dual modularity in theory perfectly reproduces the biomechanical parameters of the hip, but is unfortunately associated with fractures and severe corrosion, leading to ARMD and pseudotumor, especially in Cr-Co necks. Moreover, it provides no functional advantage, and no longer has a role outside dysplasia and other femoral deformities. Metaphyseal-diaphyseal modularity is not widespread in primary implants, and is it really necessary? Only one model has been widely studied: S-Rom™ (Depuy®). It features a metaphyseal sleeve adapting to the anatomy of the proximal femur, with a stem fitted via an inverse Morse taper. Its only interest is in case of congenital dislocation; like all metal connections, it incurs a risk of fracture and corrosion. On the other hand, modularity is widely employed in revision implants. Does it really help these procedures? The connection between a proximal femoral component of variable geometry and a diaphyseal stem with press-fit distal fixation provides a real solution to problems of length, lateralization and anteversion. Early models encountered high rates of fracture, but current implants and rigorous surgical technique have reduced this risk. Corrosion is a less serious problem, as the Morse taper undergoes only axial stress, without the friction undergone by other models subject to varus stress.

A comparison of bone union and complication rates between locking and non-locking plates in distal fibular fracture: Retrospective study of 106 cases.

BACKGROUND: Ankle fractures represents the third most frequent fracture in elderly patients. There is a current tendency to fix long bones fractures with locking plates. However, we rarely find published accounts about the use of locking plates in distal fibula fractures, except for biomechanical ones, studying human cadaveric fibula. OBJECTIVES: The main objective was to compare radiographic bone union rates at 6 and 12 weeks of follow up, then wound complications and hardware removal rates, and construct cost. STUDY DESIGN & METHODS: We retrospectively analyzed 105 patients who underwent surgery with locking plates or non-locking plates over a two-year period, out of which 42 patients were treated with non-locking plates (VIVES™ - StrykerⓇ) and 63 with locking plates (VariAx™ - StrykerⓇ,). We analyzed bone union on anterior posterior and lateral X-rays of the ankle. We collected data of wound complications and hardware removal from patient records. Multiple linear regression techniques were performed after identifying dependent variables. RESULTS: There was no significant difference between non-locking and locking plates in the radiographic bone union rate of distal fibula, respectively at 6 and 12 post-operative weeks (85.71% vs. 81%; p = 0.525 and 97.62% vs. 96.83%; p = 1). No significant difference was found in the wound complication rate between the two groups (11.9% vs. 11.12%; p = 0.9). No significant differences were found in the hardware removal rate, either with or without operative site's infection (respectively: 30.95% vs. 39.68%; p = 0.361 and 21.42% vs. 38.09%; p = 0.071). Cost efficiency is in the favor of non-locking plates. CONCLUSION: Non-locking constructs are as effective as locking constructs in the treatment of displaced distal fibula fractures at a substantially lower cost. High-quality randomized controlled trials are needed in the future to verify the finding of this study.

Factors associated with hospital stay length, discharge destination, and 30-day readmission rate after primary hip or knee arthroplasty: Retrospective Cohort Study.

BACKGROUND: In France and in the US, predictions for 2030 include an increased number of total hip arthroplasty (THA) and total knee arthroplasty (TKA) procedures together with an overall trend towards shorter hospital stays. Predictors of hospital length of stay (LOS) include the day of surgery, discharge destination, and patient comorbidities. Available data are conflicting, however, and to our knowledge predictors of LOS after THA or TKA have not been evaluated in France. Improved knowledge of these predictors would be expected to increase patient care efficiency. The objectives of this study were: (1) to determine whether the above-listed factors predict LOS after THA or TKA, (2) to identify predictors of discharge to a rehabilitation unit and of readmission within 30 days after surgery. HYPOTHESIS: Both patient-related factors unamenable to modification and modifiable organisational factors are associated with LOS after THA or TKA. MATERIAL AND METHODS: This large single-centre retrospective cohort study included all adults who underwent primary THA or TKA at our university hospital between 1 January 2015 and 31 December 2016. Non-inclusion criteria were revision arthroplasty, THA with femoral or acetabular reconstruction, TKA using a constrained hinged implant, and fracture as the reason for arthroplasty. Preoperative parameters, type of arthroplasty, and postoperative care were recorded. RESULTS: We included 938 patients with THA and 725 patients with TKA. By multivariate analysis, the likelihood of being discharged by day 5 decreased with older age (HR, 0.986; 95%CI: 0.98-0.99) and was lower by 13% in females (HR, 0,871; 95%CI: 0.77-0.986), by 39% in patients with diabetes (HR, 0.606; 95%CI: 0.5-0.73), by 68% in patients discharged to rehabilitation units (HR, 0.322; 95%CI: 0.267-0.389), and by 27% in patients who had arthroplasty on a Friday (HR, 0.733; 95%CI: 0.631-0.852). Factors predicting discharge to rehabilitation unit were older age, female gender, chronic obstructive pulmonary disease, anxiety-depressive disorder, and a history of stroke. Risk factors for 30-day readmission were male gender, obesity, and discharge to rehabilitation unit. DISCUSSION: In this study, predictors of LOS were identified using a survival model that considered age as a continuous variable, separate comorbidities, and the discharge destination. Our findings are consistent with earlier reports and confirm the strong associations linking LOS to diabetes, day of surgery, and discharge destination in France. We also identified predictors of discharge to rehabilitation and of readmission within 30 days. LEVEL OF EVIDENCE: IV, retrospective observational cohort study.

Does the direct anterior approach allow earlier recovery of walking following total hip arthroplasty? A randomized prospective trial using accelerometry.

INTRODUCTION: In total hip arthroplasty (THA), the anterior approach is attractive, being intermuscular, with theoretic functional benefit. Such benefit has been frequently claimed, but there are few data from randomized comparative studies using more precise metrics than patient satisfaction. We therefore conducted a randomized trial comparing early functional results between anterior and posterior approaches on gait analysis and functional scores. HYPOTHESIS: The study hypothesis was that there is no difference between the two approaches in terms of early recovery of walking. MATERIALS AND METHOD: A single-center single-surgeon prospective randomized study was conducted between February 2017 and April 2018. Inclusion criteria comprised: age<85 years, body-mass index (BMI)<32, and hip osteoarthritis with indication for THA. Preoperatively, the 2 groups were comparable for age, gender, BMI, Charnley, Harris, Postel-Merle-d'Aubigné and Oxford-12 scores and locomotor parameters (triaxial acceleration, step regularity and walking power). Preoperative and 3-, 6- and 12-week assessment comprised triaxial acceleration in walking and Postel-Merle-d'Aubigné, Harris and Oxford SF-12 scores. RESULTS: One hundred patients were randomized to the anterior approach (AA: n=50) and posterior approach (PA: n=50) groups. Hospital stay was comparable between groups: PA, 2.8±1.78 days [range, 2.29-3.31 days]; AA, 2.84±1.25 days [range, 2.48-3.2 days] (p=0.8). Operative time was significantly longer in AA: 70.1±11 minutes vs. 56.7±11.79 (p<0.0001). There were no significant differences in locomotor parameters (p 0.122 to 0.987) or functional scores (p 0.052 to 0.968) over the 3-month follow-up. There was no difference in cup inclination: PA, 39.6±6.87° [range, 37.65-41.55°] vs. AA, 37.74±4.2° [range, 36.55-38.93°] (p=0.09). There were 8/50 cases (16%) of neurapraxia of the lateral cutaneous nerve of the thigh in the AA group; rates for other complications did not differ between groups. CONCLUSION: Early functional results and especially objective locomotor parameters following THA were comparable between anterior and posterior approaches at 3 to 12 weeks. The approach should be chosen according to the surgeon's experience. LEVEL OF EVIDENCE: II, low-power prospective randomized study.