Modern cementless acetabular cups in total hip arthroplasty performed for primary osteoarthritis: a comparative registry study.

INTRODUCTION: Comparative studies evaluating the different material and surface finishing of acetabular components in total hip arthroplasty (THA) are lacking. Using a regional arthroplasty registry, the survival rates and the hazard ratios of different cups in THA performed for primary osteoarthritis were assessed, using endpoints: (1) every cup failure, (2) cup aseptic loosening, (3) periprosthetic infection. MATERIALS AND METHODS: The inclusion criteria were: residing patients, THA for primary osteoarthritis, Delta-on-Delta bearings, head sizes 32 mm and 36 mm. Only the most implanted cementless cups were considered and were grouped according to material and surface finishing into three cohorts: 3D printed cups (I), ultraporous tantalum or titanium- coated cups (II), second-generation cups (III). 15,737 cups were included in the study: 9,862 cups (62.7%) in cohort I, 2,067 implants (13.1%) in cohort II, 3,808 implants (24.2%) in cohort III. RESULTS: The three cohorts achieved comparable general 10-year survival rates (p = 0.62). In I and II cohorts, the survival rates of the cup types within cohorts were analogous (p = 0.86 and p = 0.31), but not in cohort III (p = 0.004). The hazard ratios for overall failure adjusted for age and sex were similar among the cohorts. Regarding cup aseptic loosening, the three cohorts had similar rates (p = 0.48) and similar adjusted hazard ratios. With periprosthetic hip infection as endpoint, the survival rates and the adjusted hazard ratios of the three cohorts were comparable (p = 0.68). CONCLUSIONS: 3D printed cups provided similar 10-year outcomes compared to ultraporous cups and second-generation cups, with no additional risks of aseptic loosening and infection. LEVEL OF EVIDENCE: IV (therapeutic study). TAKE HOME MESSAGE: - 3D printed cups provided similar 10-year outcomes compared to ultraporous cups and second-generation cups. - There is no additional risks of aseptic loosening and infection.

Head size in Delta ceramic-on-ceramic total hip arthroplasty: a comparative registry study.

INTRODUCTION: Optimal bearing size in total hip arthroplasty (THA) has not been clearly ascertained, but large diameter ceramic balls may improve function and implant stability, with minimal concerns for wear. Delta ceramic-on-ceramic (COC) THA were stratified based on head diameter (32, 36 and 40 mm), aiming to assess: 1) survival rates, reasons for revision and hazard ratios for failure; 2) survival rates and hazard ratios for aseptic loosening, dislocation/primary instability, liner failure. MATERIALS AND METHODS: A regional arthroplasty registry was enquired about Delta COC THA performed for primary osteoarthritis, stratified by head size. 13,161 primary cementless THAs were included in the study, with a mean follow-up of 5.7 years (range: 0-17): 3980 (30.2%) 32 mm balls, 8327 (63.3%) 36 mm heads, 854 (6.5%) 40 mm heads. RESULTS: The three cohorts achieved similar survival rates (p = 0.99) and adjusted hazard ratios (p > 0.05). No revisions for head breakage or metallosis occurred. When revision for cup aseptic loosening was the endpoint, the survival rates of three cohorts (p = 0.08) and the adjusted hazard ratios (p > 0.05) were similar. The three cohorts achieved comparable survival rates when revision for dislocation/primary instability was the endpoint (p = 0.08). When the endpoint was revision for liner breakage, 32 mm cohort showed higher rates of revision (p = 0.01). No liner failure was detected in the 40 mm cohort. CONCLUSIONS: 32 mm, 36 mm and 40 mm provided similar 10-year survival rates in Delta COC THA. 40 mm heads emerged as safe options but did not lower the revisions for dislocations/primary instability. LEVEL OF EVIDENCE: IV (therapeutic study).

Total knee arthroplasty survival rates are lower in younger men, as well as rheumatoid patients and after previous high-tibial osteotomy: A registry study.

PURPOSE: The purpose of this study was to investigate if patient's gender significantly affected the long-term outcome of patients undergoing total knee arthroplasty (TKA) and to provide a cross-gender comparison of a large patient sample from a single regional register. METHODS: The Registry of Prosthetic Orthopedic Implant of Emilia Romagna (RIPO) investigated all primary TKAs performed from July 2000 to December 2020 by collecting data of men and women separately. Primary bicompartmental and tricompartmental TKAs were included. The survival rates and the reasons for revision were assessed to check if any other factor could have influenced implant failure. RESULTS: In total, 66,032 TKAs were included and analysed, comprising 46,774 women and 19,258 men. The 15-year Kaplan-Meier survival percentage was 93.6% for women and 92.5% for men (p = 0.001). Men exhibited a higher revision risk following primary TKA (p = 0.012), particularly when the primary diagnosis was arthritis resulting from rheumatic disorders (p = 0.018) and arthritis following high-tibial osteotomy (p = 0.024). Failure risk was also higher for men below the age of 60 years (p = 0.038). CONCLUSION: The long-term outcome in TKA showed significant differences between men and women, with a significantly lower survival rate in men at 15 years, especially when they are under 60 years old or with a diagnosis of rheumatic disorders or arthritis following high-tibial osteotomy. It is necessary to design specific studies to have relevant data concerning gender differences in prosthetic surgery and to customise treatments to improve outcome and patient satisfaction. LEVEL OF EVIDENCE: Level III.

Total Hip Arthroplasty for Low-Grade Developmental Hip Dysplasia Changes the Ipsilateral Knee Alignment on the Axial and Coronal Planes.

BACKGROUND: There is a paucity of data regarding the post-operative influence of total hip arthroplasty (THA) on the axial and coronal alignments of the ipsilateral knee. A CT study was designed to assess the post-THA changes in axial and coronal knee alignments in low-grade dysplastic hips. METHODS: Forty Crowe I-II dysplastic hips in 37 patients were assessed: a pre-operative CT scan from the fourth lumbar vertebra to the tibial plateaus was compared to a similar post-operative CT scan performed after a minimum of 2 years after THA. RESULTS: THA implantation caused significant post-operative changes in terms of the rotation height (2 mm lowering; p = 0.003); center of rotation medialization (10 mm medialization; p < 0.001); femoral offset (11 mm increase; p < 0.001); femoral antetorsion (22° internal rotation; p < 0.001), and hip internal rotation (9° internal rotation; p < 0.001). The femoral axis angle deviated in the valgus (5.5° ± 1.1°, p < 0.001) and the mechanical lateral distal femoral angle deviated in the varus (86° ± 2.7°, p = 0.001). The pelvic-tibial alignment changed from 88.2° ± 11.7° to 96° ± 9.3° (p < 0.001). Patellar alignment was not influenced. CONCLUSIONS: In conclusion, THA imposes significant changes in low-grade dysplastic hips: all the modifications tend to neutralize the coronal alignment and, mostly, the rotational alignment, without substantial and durable variations of the patellofemoral joint. Large clinical trials should confirm whether radiological changes impact anterior knee pain and patellar stability.

Revision Hip Arthroplasty Using a Modular Head-Neck Adapter System and a Ceramic Head: 5-Year Clinical and Radiographic Outcomes.

INTRODUCTION: A modular head-neck adapter system may help surgeons restore the proximal hip biomechanics in revision hip arthroplasty. However, the clinical and radiographic 5-year outcomes of the system are still scarcely reported. The aim of this study is the assessment of (1) complications and survival rates, (2) clinical and (3) radiological outcomes of the modular head-neck adapter system with a ceramic head in revision hip arthroplasty at 5 years. METHODS: 32 revision hip arthroplasties using a modular head-neck adapter system and a ceramic head were retrospectively recorded. Preoperative demographic and implant features were collected. Clinical and radiographic outcomes, failures and reasons for re-revisions were recorded at the last follow-up. RESULTS: A mean follow-up of 59.8 ± 26 months was achieved. The survival rate was 90.6% at 5 years. Post-operative complications occurred in nine cases (28.1%): two dislocations (6.2%), one aseptic cup loosening (3.1%) requiring re-revision, one (3.1%) persistent pelvic pseudotumor requiring embolization. No mechanical failures of the adapter or ceramic head occurred. The mean post-operative HHS score was 84.4 points. Thirteen cases (40.6%) showed optimal radiographic cup osseointegration, and 17 hips (53.1%) showed valid stem osseointegration. The mean post-operative femoral offset was 48.84 mm, larger than the contralateral side (p = 0.02). The post-operative lateralization of the hip joint was 38.09 mm, close to the contralateral side (p = 0.4). CONCLUSIONS: In revisions, the modular head-neck adapter system with ceramic head provided good clinical outcomes and acceptable radiographic reconstruction of hip biomechanics, with a survival rate of 87.9% at 5 years.

Higher failure rate of secondary patellar resurfacing following bicompartmental knee arthroplasty.

INTRODUCTION: The role of secondary patellar resurfacing (SPR) in anterior knee pain (AKP) is still debated in literature. A regional arthroplasty registry was investigated, aiming to: (1) assess the survival rate of SPR; and (2) compare SPR to tricompartmental TKA. MATERIALS AND METHODS: The regional arthroplasty registry RIPO was investigated about all SPRs performed after bicompartmental arthroplasty. The survival rates and the reasons for revision were assessed as any other factor that could have influenced implants failure. SPR survivorship was compared to tricompartmental TKAs. RESULTS: 406 SPRs performed after bicompartmental arthroplasty were analyzed. The survival rates were 80.6% (CI 95% 75.9-84.5) at 5 years and 77.6% (CI 95% 72.4-82) at 7 years. Half of the SPRs was performed 0.9-2.4 years after the index bicompartmental arthroplasty. SPR achieved lower survival than tricompartmental TKA (80.6% vs 96.7%, p < 0.001), with an adjusted hazard ratio for failure of 5.5 (CI 95% 4.2-7.1, p < 0.001). SPRs performed within 2 years after primary implant had a significantly higher rates of failure when compared to tricompartmental TKA (HR: 6.4, CI 95% 4.8-8.4, p < 0.001). CONCLUSION: SPR after bicompartmental knee arthroplasty showed modest 5- and 7-year survival rates, worse than primary tricompartmental TKA. When SPRs are performed within 2 years after primary arthroplasty, a significant higher risk of failure should be expected, highlighting than appropriate pre-operative work-up and patient selection is crucial for SPR successful outcome. LEVEL OF EVIDENCE: III, therapeutic study.

Comparison of single taper and dual taper versions of the same stem design in total hip arthroplasty for primary osteoarthritis.

BACKGROUND: In total hip arthroplasty (THA), the outcomes of single taper (ST) and dual taper (DT) versions of the same stem design have been scarcely studied. A registry study comparing ST and DT versions of the same stem design was designed, aiming to assess: (1) the survival rates and the hazard ratios for failure; (2) the survival rates and the hazard ratios for failure using stem-focused endpoints. MATERIAL AND METHODS: A regional arthroplasty registry was interrogated about stem designs with ST and DT versions in cementless THAs performed for primary osteoarthritis. Only the same cup and ceramic-on-ceramic bearings were included: the DT stems had a titanium-on-titanium modularity. Demographic and implant features were recorded. Survival rates and hazard ratios were evaluated and compared. Stem-focused endpoints were also investigated. RESULTS: A total of 5359 THAs were included, with three stem designs. The two versions of every stem showed different demographics and implant-related features: ST versions were preferentially implanted in heavier young men. For each stem, the two versions had similar survival rates at 5 years (p = 0.076; p = 0.319; p = 0.616) and similar adjusted hazard ratios for failures (p = 0.084; p = 0.308; p = 0.729). When stem-focused endpoints were adopted, the ST and DT versions of the three stems achieved similar survival rates (p = 0.710; p = 0.784; p = 0.983) and similar adjusted hazard ratios (p = 0.647; p = 0.858; p = 0.787). Three neck breakages occurred (0.0007% of all the modular implants). CONCLUSIONS: ST and DT versions of the same stem design did not show any differences in terms of survival rates and hazard ratios for failures at 5 years. LEVEL OF EVIDENCE: IV.

A Modular Head-Neck Adapter System and Ceramic Heads in Revision Hip Arthroplasty: A Registry Study on 354 Implants.

BACKGROUND: Five- to 10-year outcomes of a modular head-neck adapter system with ceramic heads in revision hip arthroplasty on large populations are still lacking. A registry study about modular adapter system with Delta ceramic head in revisions was designed, aiming to assess (1) the survival rates of the device, (2) the reasons for re-revisions of the device, and (3) a comparison to factory assembled titanium sleeve and Delta head cohort in revision hips. METHODS: Using a regional arthroplasty registry, we investigated the modular adapter system with a ceramic head in revision hips. Demographics, implant features, and reasons for revision were recorded. Survival rates and reasons for re-revision were assessed. The modular adapter system with the ceramic ball was compared to a factory-assembled ceramic titanium-sleeved head in revisions, acting as a control group. There were 354 revisions included at a mean follow-up of 5 years (range, 0 to 13). RESULTS: The 5- and 7-year survival rates were 87.9% and 86.9%, respectively. Dislocations (2.8%) and cup aseptic loosening (4.2%) were the 2 most frequent reasons for re-revision. No breakage of the adapter system or the ceramic head occurred. A femoral neck failed (0.3%). No implant features, offset (P = .088) or skirted (P = .870) tapers, impacted on failures. No differences between the 2 cohorts were found regarding survival rates (P = .696) and reasons for re-revision (dislocations, P = .983; cup aseptic loosening, P = .296). CONCLUSION: The modular head neck adapter system with a ceramic head seems to be a valid option in revisions at 5 and 7 years, without additional risk of implant breakage in this registry.

Mid-term outcomes of revision hip arthroplasty due to titanium modular neck failure.

INTRODUCTION: The current strategy for modular neck failures in total hip arthroplasty (THA) is calibrated on CrCo neck failures. Stem revision is usually required, but the procedure is challenging and achieves modest outcomes (up to 20% of re-revisions at short-term). No study reports revision strategies and outcomes after Ti neck failures. Aims of the study were to evaluate: (1) demographic and implant features of the cohort to be revised, (2) intra-operative findings and surgical revision strategies and (3) clinical and radiological post-revision outcomes. MATERIALS AND METHODS: Hospital database was enquired about revisions due to Ti neck failures in primary THAs. Sixty-five revisions were enrolled (all with the same modular system). Neck exchange was attempted as the first-line treatment. Patients were clinically and radiographically evaluated after revision. RESULTS: The revision cohort encompassed fatigue neck fractures occurred 4.4 ± 2.6 years after THA: patients < 65 years and/or > 80 kg (98.5%) were predominant. Fifty-three neck exchanges were performed (81.5%). Eleven failures required stem revisions (16.9%), generally due to demanding neck extraction. Six complications occurred after neck exchange (11.3%), among them 2 acute infections requiring surgery (3.8%). Among stem revisions, one aseptic loosening and one neck re-fracture (18.5%) required re-revisions. At a mean follow-up of 7.1 ± 4 years, the neck exchange cohort achieved a mean HHS of 89.1 ± 6.3 (stem revisions: 84.1 ± 10.9). CONCLUSIONS: Revisions for Ti neck failures were predominantly performed due to fatigue fractures. In case of failures, neck exchange is a feasible procedure in most of the cases, with good outcomes at 7 years. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Cup Overhanging in Anatomic Socket Position or High Hip Center of Rotation in Total Hip Arthroplasty for Crowe III and IV Dysplasia: A CT-Based Simulation.

Cup overhanging in total hip arthroplasty is a predisposing factor to iliopsoas impingement. In dysplastic hips, cup implantation was simulated in an anatomic hip center of rotation (AHCR) and in high hip center (HHCR). We sought to assess: (1) the percentage of prominent cups; (2) quantify the cup protrusion at different sites on frontal, axial and sagittal views. In 40 Crowe III-IV hips, using a 3D CT-based planning software, cup planning in AHCR and HHCR (CR height ≥ 20 mm) was performed for every hip. Cup prominence was assessed on every plane. HHCR cups were less anteverted (p < 0.01), less medialized (p < 0.001) and less caudal (p = 0.01) than AHCR sockets. AHCR cups were more frequently prominent on at least one plane (92.5% vs. 77.5%), with minimal agreement between the two configurations (k = 0.31, p = 0.07). AHCR cups protruded more than HHCR sockets in the sagittal (p = 0.02) and axial planes (p < 0.001). Axially, at the center of the cup, prominence 6−11 mm occurred in nine (22.5%) AHCR and one (2.5%) HHCR socket. In conclusion, while a routine high hip center should not be recommended, cup placement at a center of rotation height < 20 mm is associated with higher rates and magnitudes of anterior cup protrusion in severe dysplasia.

Software-related recalls in computer-assisted hip and knee arthroplasty.

PURPOSE: Computer-assisted arthroplasty supports the surgeons in planning, simulating, and performing the replacement procedure, using robotic or navigation technologies. However, the safety of the technology has not been widely ascertained. Food and Drug Administration (FDA) database was interrogated about software-related recalls in computer-assisted arthroplasty, aiming to assess: (1) the incidence, (2) the root causes, and (3) the actions taken due to recalls. METHODS: The Medical Device Recalls database was investigated about software-related recalls in computer-assisted hip and knee arthroplasty surgery, between 2017 and 2022. The incidence of the software-related recalls, the root causes according to FDA and manufacturers, and the corrective actions taken by firms were determined. RESULTS: Eighteen recall numbers could be identified (1.6%), corresponding to 11 recall events. A total of 4634 units were involved. The FDA determined root causes were: software design (66.6%), design change (22.2%), manufacturing deployment (1, 5.6%), and design manufacturing process (5.6%). Among the manufacturers' reasons for recalls, a specific error was declared in 16 cases (88.9%). In seven cases (43.8%), a coding error about lower limb alignment assessment was identified. Seventeen software-related recalls (94.4%) were classified as class 2; only one case was class 3 (5.6%). Return of the device was the main action taken by firms (8, 44.4%), followed by software update (7, 38.9%). CONCLUSION: Software-related recalls in computer-assisted hip and knee arthroplasty were quite uncommon among all the recalls, deemed non-life threatening and usually due to software design errors. The main actions taken by manufacturers were the return of the device or the software update.

Single-taper conical tapered stem in total hip arthroplasty for developmental dysplasia of the hip: A long-term evaluation.

INTRODUCTION: Conical tapered stems may be useful implants to manage the reconstruction of complex dysplastic anatomies. The aims of this paper were to assess: 1) the preoperative CT features of the dysplastic femurs; 2) survival rates, complications and reasons for revision; 3) the clinical outcomes; 4) the radiographic outcomes of single-taper conical stems in dysplasia (defined as center edge angle < 20°) at a long-term follow-up. HYPOTHESIS: Monoblock conical stem provides a 10-year survival rate of at least 95%, with excellent clinical outcomes and bony ingrowth. MATERIALS AND METHODS: In total, 100 THAs in 85 patients (15 bilateral cases) were enrolled. The average age of the patients at surgery was 50.9±11.5 years. Assessment of the native femoral morphology was performed using CT-scan, coronal (neck-shaft angle, offset, center of rotation position) and axial parameters (anteversion, mediolateral and anteroposterior femoral diameters). Clinical (HHS score) and radiological (osseointegration, subsidence and offset reconstruction) outcomes were evaluated at the last available follow-up. RESULTS: The mean follow-up was 9.34±5.61 years. Severely distorted anatomies from Crowe I to Crowe IV were included, with a mean canal flare of 4.3 and a mean femoral antetorsion of 34°. The survival rates were stable at long-term (98.9% at 10 and 15 years): no aseptic loosening occurred. The mean postoperative HHS was 89.8±6.8 points. Ninety-nine percent of the stems showed bone ingrowth, from 6 months to the last available follow-up. Subsidence occurred in 18% of the cases (mean value: 2.5mm, range: 1-6mm) in the first month, with subsequent stabilization. A mild proximal stress shielding occurred in 28% of the THAs. Radiolucent lines were detected in the 8% of the cases. There was a postoperative loss of offset in 12% of the cases. DISCUSSION: Conical stems in dysplastic hips achieved bony ingrowth at long-term outcome, even in complex anatomies. Subsidence, proximal stress shielding and imperfect offset restoration may occur with this implant. LEVEL OF PROOF: IV; retrospective study.

Titanium modular stems in total hip arthroplasty due to developmental dysplasia: a registry comparison with single-taper implants.

INTRODUCTION: The routine use of proximal femoral modularity was discouraged in total hip arthroplasties (THAs). However, titanium dual-taper (DT) implants may provide some advantages over single-taper (ST) stems in cases of complex deformity. A registry study comparing ST and DT stems in dysplasia was designed, aiming to assess: (1) survival rates at long-term; (2) reasons for revision; (3) the profile of failed implants. METHODS: The arthroplasty registry RIPO was investigated for cementless THAs performed for dysplasia since 2000. ST implants were compared to titanium-on-titanium DT stems. Demographics and implant features were collected. Survival rates and reasons for revision were compared. The profile of DT stem failures in dysplasia was defined. RESULTS: 6429 implants were included in the study, 3642 ST and 2787 DT. The demographic and implant features of the 2 cohorts were not comparable. The DT cohort achieved higher survival rates at long-term (93.9% vs. 91.6%, p = 0.018). DT implants showed a higher rate of implant breakage (0.6%, p = 0.011) and a lower rate of aseptic loosening (p = 0.005). There were no differences in terms of revisions for dislocation. No metallosis occurred. There were more revisions in DT implants in males <65 years, with a 28-mm head size or smaller. CONCLUSIONS: Modularity did not result in lower survival rates in dysplastic patients and may even reduce the rate of aseptic loosening in comparison to ST stems. The rate of implant breakage is not negligible. Younger males are not good candidates for titanium DT stems.

One-stage complete eradication and revision hip due to pseudotumor in metal-on-metal hip arthroplasty.

Background: The correct management and treatment of pseudotumors due to metal-on-metal (MOM) hip arthroplasty are still debated. The purpose of this study is to analyze the surgical treatment and the clinical and radiographic 3-year outcomes of MOM arthroplasty revisions due to pseudotumor treated with a strategy of excision and revision. Methods: Consecutive, retrospective series of 21 patients (8 males/13 females) with pseudotumor due to MOM hip arthroplasty was surgically treated at a single tertiary center. Demographic, clinical, radiological and implant-related features were collected pre-operatively. Post-revision clinical and radiographic parameters were evaluated. Chromium (Cr) and cobalt (Co) blood samples were collected before and after surgery. Results: Three patients (14.2%) with pseudotumor underwent a resection arthroplasty due to infection (perioperative finding) and could not be reimplanted due to septic relapses. Twenty (95.2%) pseudotumors were completely resected. Revisions [2 total hip reimplantations (11.1%) and 16 isolated component revisions (88.9%)] were performed with non-MOM couplings. A clinical improvement at a mean post-revision follow-up 3.3 years [standard deviation (SD), ±2.2 years] was observed, from 50.3 (SD, ±4.6) to 88.3 (SD, ±9.2) Harris hip score (HHS) points (P<0.001). Among revisions, there were 5 complications (23.8%): 1 dislocation, 1 psoas impingement, and 3 infections (14.2%). No re-revision was carried out. Three (14.2%) pseudotumors recurred: 1 was surgically treated, 1 was treated with selective arterial embolization, and 1 clinically followed. At the final follow-up, Cr and Co blood ions beyond the threshold decreased from 85.7% cases to 0% in the seven patients that could be evaluated. Conclusions: The one-stage strategy of radical excision and revision with non-MOM couplings in pseudotumors due to MOM hip arthroplasty achieved good 3-year outcomes. However, complications were frequent (23%). Recurrences were not rare (14%) and did not require implant re-revision.

Preoperative and postoperative risk factors for periprosthetic joint infection in primary total hip arthroplasty: A 1-year experience.

BACKGROUND: Periprosthetic joint infection (PJI) in primary total hip replacement (THR) is one of the most important threats in orthopedic surgery, so one important surgeon's target is to avoid or early diagnose a PJI. Although the incidence of PJI is very low (0.69%) in our department, with an average follow-up of 595 d, this infection poses a serious threat due to the difficulties of treatment and the lower functional outcomes after healing. AIM: To study the incidence of PJI in all operations occurring in the year 2016 in our department to look for predictive signs of potential infection. METHODS: We counted 583 THR for 578 patients and observed only 4 cases of infection (0.69%) with a mean follow-up of 596 d (min 30, max 1451). We reviewed all medical records to collect the data: duration and time of the surgery, presence, type and duration of the antibiotic therapy, preoperative diagnosis, blood values before and after surgery, transfusions, presence of preoperative drugs (in particularly anticoagulants and antiaggregant, corticosteroids and immunosuppressants), presence of some comorbidities (high body mass index, blood hypertension, chronic obstructive pulmonary disease, cardiac ischemia, diabetes, rheumatological conditions, previous local infections). RESULTS: No preoperative, intraoperative, or postoperative analysis showed a higher incidence of PJI. We did not find any class with evident major odds of PJI. In our study, we did not find any border value to predict PJI and all patients had similar values in both groups (non-PJI and PJI). Only some categories, such as female patients, showed more frequency of PJI, but this difference related to sex was not statistically significant. CONCLUSION: We did not find any category with a higher risk of PJI in THR, probably due to the lack of few cases of infection.

Which stem in total hip arthroplasty for developmental hip dysplasia? A comparative study using a 3D CT-based software for pre-operative surgical planning.

BACKGROUND: Stem choice in total hip arthroplasty (THA) for hip dysplasia is still controversial. The aims of the study were to evaluate (1) which stem design provided the highest percentage of adequate reconstructions in THA for dysplasia and (2) any correlation between the reconstructions provided by the stems and the native femoral morphology. MATERIALS AND METHODS: 150 CT scans including 200 adult dysplastic hips were randomly selected. Using the 3D CT-based software Hip-Op for surgical planning, the native hip anatomy was studied. Then, a single wedge tapered stem, an anatomical stem and a conical tapered stem were simulated in every hip. An adequate reconstruction of hip biomechanics was obtained when combined anteversion, offset restoration, coronal and sagittal tilt, canal filling and leg lengthening were inside the normal ranges. RESULTS: Conical stems achieved the highest percentage of adequate reconstructions (87%, p < 0.0001). The anatomical stem was the worst performer. Single wedge and anatomical stem acceptability was mainly influenced by the combined anteversion. Stem anteversion was correlated with the femoral anteversion (fair correlation), the calcar femorale (fair) and the mediolateral femoral diameter at isthmus (poor). When the femoral anteversion was ≥ 25°, combined anteversion was very acceptable for the conical stem (99.2%), whereas the rate of acceptable combined anteversion for the single wedge tapered stem was 71.4%, and that for the anatomical stem was 51.6% (p < 0.0001). CONCLUSIONS: Stem choice in developmental hip dysplasia is mainly driven by appropriate combined anteversion, which is dependent on the coronal and axial femoral morphologies. As a rule of thumb, tapered stems are adequate when femoral anteversion is < 25°; conical stems should be adopted for higher anteversions. LEVEL OF EVIDENCE: IV.

A case-driven hypothesis for multi-stage crack growth mechanism in fourth-generation ceramic head fracture.

BACKGROUND: Ceramic bearings are used in total hip arthroplasty due to their excellent wear behaviour and biocompatibility. The major concern related to their use is material brittleness, which significantly impacts on the risk of fracture of ceramic components. Fracture toughness improvement has contributed to the decrease in fracture rate, at least of the prosthetic head. However, the root cause behind these rare events is not fully understood. This study evaluated head fracture occurrence in a sizeable cohort of patients with fourth-generation ceramic-on-ceramic implants and described the circumstances reported by patients in the rare cases of head fracture. METHODS: The clinical survivorship of 29,495 hip prostheses, with fourth-generation ceramic bearings, was determined using data from a joint replacement registry. The average follow-up period was 5.2 years (range 0.1-15.6). Retrieval analysis was performed in one case for which the ceramic components were available. RESULTS: Clinical outcomes confirmed the extremely low fracture rate of fourth-generation ceramic heads: only two out of 29,495 heads fractured. The two fractures, both involving 36 mm heads, occurred without a concurrent or previous remarkable trauma. Considering the feature of the fractured head, a multi-stage crack growth mechanism has been hypothesized to occur following damage at the head-neck taper interface. CONCLUSIONS: Surgeons must continue to pay attention to the assembly of the femoral head: achieving a proper head seating on a clean taper is a prerequisite to decrease the risk of occurrence of any damage process within head-neck junction, which may cause high stress concentration at the contact surface, promoting crack nucleation and propagation even in toughened ceramics.

Constraint in complex primary total knee arthroplasty: rotating hinge versus condylar constrained implants.

INTRODUCTION: Condylar constrained knee arthroplasties (CCKAs) and rotating hinge knee arthroplasties (RHKAs) achieved good outcomes in complex primary total knee arthroplasties (TKAs); however, long-term comparative studies are few. Using an arthroplasty registry, we sought to assess and compare in CCKAs and RHKAs: (1) the intra-operative rates of complications, (2) the survival rates, (3) the reasons for revision, and (4) the adjusted hazard ratios for failure. MATERIALS AND METHODS: 1432 constrained implants in primary TKAs performed for non-oncological indications were included: 703 RHKAs, 729 CCKAs. The two groups were comparable regarding age and gender. Kaplan-Meier curves were used to compare survival rates, multivariate analyses to assess the hazard ratios for failures. RESULTS: The mean follow-up was 4.1 years (range 0-16.3) for CCKAs and 6.8 years (0-18.1) for RHKAs. The intra/peri-operative complications were similar in both the cohorts, with similar rates of femoral and tibial fractures. 10-year implant survival rates were similar in both the cohorts (91.9%, CI 95% 89.2-93.9% in RHKAs; 93.4%, CI 95% 90.3-95.6% in CCKAs). Periprosthetic infection was the most common reason for revision in the two cohorts, followed by aseptic loosening. Breakage occurred in 3 RHKAs (0.4%). CCKAs and RHKAs had a similar distribution of revision causes. Males aged less than 60 had significantly more failures, regardless the constraint degree. Unstemmed CCKAs significantly failed more than RHKAs and stemmed CCKAs. CONCLUSIONS: Both modern CCKAs and RHKAs are viable long-term solutions in complex primary TKAs. More failures should be expected in males aged less than 60. LEVEL OF EVIDENCE: IV, Therapeutic study.

Isolated arthroscopic treatment of intra-articular pathologies in mild hip dysplasia: a short-term case control study.

PURPOSE: The aim is to compare the results of isolated hip arthroscopy in patients with borderline dysplasia with Lateral center edge angle (LCEA) between 18° and 25° with a control group of patients with normal LCEA (> 25°). METHODS: Fifty hip arthroscopies performed in 45 patients were retrospectively evaluated. Exclusion criteria were: age > 40, hip arthritis > grade 2 according to Tonnis classification, femoral head avascular necrosis, pediatric's orthopaedics conditions and true dysplasia with LCEA < 18°.Two groups were identified: group A with 15 hips with LCEA between 25° and 18° and Group control B made of 35 hips with LCEA > 25°. RESULTS: The groups were homogeneous for demography and pre-operative WOMAC and HOOS. Osteoplasty for CAM were performed in 100% of patients in both groups, only in 12 hips (34.4%) in group B we had both femoral and acetabular osteoplasty. Labral repair was performed in 86% of patients in group A, in 60% of patients in group B, capsular plication in 93% of group A, in 5% of case of group B. WOMAC and HOOS statically significant improved in both groups at final follow-up (24 months). No cases in both groups required conversion to total hip arthroplasty. Clinical outcomes of study group were comparable to the control group. CONCLUSION: Even if the present small series is not conclusive, we suggest isolated arthroscopic management of patients with FAI and LCEA between 18° and 25°, but capsular plication and careful labral management are strongly recommended. LEVEL OF EVIDENCE: Level IV.