Revision total hip arthoplasty: factors associated with re-revision surgery

Impact of fixation method on femoral bone loss: a retrospective evaluation of stem loosening in first-time revision total hip arthroplasty among two hundred and fifty five patients

PURPOSE

Implant loosening represent the most common indication for stem revision in hip revision arthroplasty. This study compares femoral bone loss and the risk of initial revisions between cemented and uncemented loosened primary stems, investigating the impact of fixation method at primary implantation on femoral bone defects.

METHODS

This retrospective study reviewed 255 patients who underwent their first revision for stem loosening from 2010 to 2022, receiving either cemented or uncemented stem implants. Femoral bone loss was preoperatively measured using the Paprosky classification through radiographic evaluations. Kaplan-Meier analysis estimated the survival probability of the original stem, and the hazard ratio assessed the relative risk of revision for uncemented versus cemented stems in the first postoperative year and the following two to ten years.

RESULTS

Cemented stems showed a higher prevalence of significant bone loss (type 3b and 4 defects: 32.39% vs. 2.72%, p < .001) compared to uncemented stems, which more commonly had type 1 and 2 defects (82.07% vs. 47.89%, p < .001). In our analysis of revision cases, primary uncemented stems demonstrated a 20% lower incidence of stem loosening in the first year post-implantation compared to cemented stems (HR 0.8; 95%-CI 0.3-2.0). However, the incidence in uncemented stems increased by 20% during the subsequent years two to ten (HR 1.2; 95%-CI 0.7-1.8). Septic loosening was more common in cemented stems (28.17% vs. 10.87% in uncemented stems, p = .001). Kaplan-Meier analysis indicated a modestly longer revision-free period for cemented stems within the first ten years post-implantation (p < .022).

CONCLUSION

During first-time revision, cemented stems show significantly larger femoral bone defects than uncemented stems. Septic stem loosening occurred 17.30% more in cemented stems.

Infection Rates After Aseptic Revision Total Hip Arthroplasty With Extended Oral Antibiotic Prophylaxis

INTRODUCTION

Few US studies have investigated the efficacy of extended oral antibiotic prophylaxis (EOAP) in the prevention of periprosthetic joint infection (PJI) after aseptic revision total hip arthroplasty (R-THA). This study compared PJI rates in aseptic R-THA performed with EOAP with PJI rates in published studies of aseptic R-THA patients not receiving EOAP.

METHODS

Prospectively documented data on 127 consecutive aseptic R-THAs were retrospectively reviewed. Evidence-based perioperative infection prevention protocols were used, and all patients were discharged on 7-day EOAP. Superficial and deep infections at 30 and 90 days postoperatively and at mean latest follow-up of 27.8 months were statistically compared with all US studies reporting the prevalence of PJI after aseptic R-THA. Complications related to EOAP within 120 days of the index procedure also are reported.

RESULTS

No superficial or deep infections were observed at 30 and 90 days postoperatively when 7-day postdischarge EOAP was used. Superficial and deep infection rates were 1.57% (two patients) and 3.15% (four patients) at mean latest follow-up, respectively. Comparisons with published 30-day PJI rates of 1.37% ( P = 0.423) and 1.85% ( P = 0.257) were not statistically significant. Two of four comparisons with published 90-day PJI rates of 3.43% ( P = 0.027) and 5.74% ( P = 0.001) were statistically different. The deep PJI rate of 3.15% at mean latest follow-up was significantly lower than two of three published rates at equivalent follow-up including 10.10% ( P = 0.009) and 9.12% ( P = 0.041). No antibiotic-related complications were observed within 120 days of the index procedure.

DISCUSSION

Study findings possibly support the use of EOAP after aseptic R-THA to prevent catastrophic PJI with revision implants, indicating that the efficacy of EOAP cannot be definitively ruled-in or ruled-out based on available evidence.

Contemporary Aseptic Revision Total Hip Arthroplasty in Patients ≤50 Years of Age: Results of >500 Cases

BACKGROUND

There has been a paucity of long-term outcomes data on aseptic revision total hip arthroplasties (THAs) in the young adult population. The purpose of this study was to evaluate implant survivorship, complications, and clinical outcomes in a large cohort of contemporary aseptic revision THAs in patients ≤50 years of age at the time of the surgical procedure.

METHODS

We identified 545 aseptic revision THAs performed at a single academic institution from 2000 to 2020 in patients who were 18 to 50 years of age. Patients who underwent conversion THAs and patients with a history of any ipsilateral hip infection were excluded. The mean age was 43 years, the mean body mass index (BMI) was 29 kg/m2, and 63% were female. The index indication for revision THA was aseptic loosening in 46% of cases, polyethylene wear or osteolysis in 28% of cases (all revisions of conventional polyethylene), and dislocation in 11% of cases. There were 126 hips (23%) that had undergone at least 1 previous revision (median, 1 revision [range, 1 to 5 revisions]). The mean follow-up was 10 years.

RESULTS

In the entire cohort, the 20-year survivorship free of any re-revision was 76% (95% confidence interval [95% CI], 69% to 82%). There were 87 re-revisions, with 31 dislocations, 18 cases of aseptic loosening of the femoral component, and 16 periprosthetic joint infections (PJIs) being the most common reasons for re-revision. Dislocation as the indication for the index revision was associated with an increased risk of re-revision (hazard ratio, 2.9; p < 0.001). The 20-year survivorship free of any reoperation was 73% (95% CI, 66% to 78%). There were 75 nonoperative complications (14%), including 32 dislocations. The mean Harris hip score significantly improved (p < 0.001) from 65 preoperatively to 81 at 10 years postoperatively.

CONCLUSIONS

Contemporary aseptic revision THAs in patients ≤50 years of age demonstrated a re-revision risk of approximately 1 in 4 at 20 years. Dislocation, aseptic loosening of the femoral component, and PJI were the most common reasons for re-revision. Index revision THAs for dislocation had a 3 times higher risk of re-revision.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Decreased Instability in High-Risk (Hip-Spine 2B) Patients After Modifications of Surgical Planning and Technique

BACKGROUND

Patients undergoing primary total hip arthroplasty (THA) who have spinal deformity and a stiff spine are the highest-risk group for instability. Despite the increasing use of dual-mobility cups and large femoral heads, dislocation remains a major complication after THA. Preoperative planning becomes a critical aspect of ensuring precise component positioning within a safe zone. The purpose of this study was to investigate dislocation rates over a 9-year period.

METHODS

A retrospective review of 4,731 THAs performed by 3 orthopaedic surgeons between January 2014 and March 2023 was performed. Spinopelvic measurements were conducted to determine the hip-spine classification group for each patient. Only patients classified as 2B (pelvic incidence-lumbar lordosis > 10° and Δsacral slope < 10°) were eligible. Both absolute and relative dislocation frequencies were then analyzed using time-series analysis techniques and Fisher's exact tests.

RESULTS

A total of 281 hip-spine 2B patients undergoing primary THA were eligible for analysis (57% women; mean age, range: 66 years, 23 to 87; mean body mass index, range: 28, 16 to 45). The overall dislocation rate was 4.3%. Use of femoral head sizes ≥ 40 mm increased from 4% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001), while the use of dual-mobility cups decreased from 100% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001). Acetabular component planning was changed from the supine plane to the standing plane in February 2020. Those changes in surgical practice were notably correlated with a significant decrease in dislocation rates from 6.8% in 2014 to 2019 to 1.5% in 2020 to 2023 (P = .03).

CONCLUSIONS

Our study demonstrates that the introduction of advanced preoperative THA planning to the standing plane, coupled with precise intraoperative technology for implant placement, can significantly reduce the risk of instability in high-risk THA patients. Notably, we observed a significant decrease in dislocation rates, which aligned with the shift in surgical practice.

LEVEL OF EVIDENCE

IV.

Aseptic Revision Total Hip Arthroplasty Through an Anterior Approach: Survivorship and Risk Factors for Re-Revision

BACKGROUND

The utilization of anterior-based approaches for total hip arthroplasty (THA) is increasing. Literature on the outcomes of revision THA (rTHA) through an anterior approach, however, is sparse. This study reports the survivorship and risk factors for re-revision in patients undergoing aseptic rTHA through an anterior approach.

METHODS

This was a single-institution, retrospective cohort analysis of patients who underwent aseptic rTHA through an anterior approach (direct anterior, anterior-based muscle sparing) from January 2017 to December 2021, regardless of the original surgical approach. Exclusion criteria were age <18 years, conversion THA, and septic revisions. Patient demographics, complications, and postoperative outcomes were collected. Kaplan-Meier curves were used to measure survivorship while Cox regression analyses were used to identify risk factors for re-revision of THA.

RESULTS

We identified 251 total anterior rTHAs, of which 155 were aseptic anterior revisions. There were 111 patients (111 rTHAs; 63 anterior-based muscle sparing and 48 direct anterior) who met criteria and had a mean follow-up of 4.2 years (range, 2.1 to 6.9). There were a total of 54 (49%) anterior-based index approaches and 57 (51%) posterior index approaches. The most common indications for rTHA were femoral loosening (n = 25, 22.5%), followed by instability (n = 16, 14.4%) and wear or osteolysis (n = 16, 14.4%). At 2 years, the survivorship from reoperation and re-revision was 89% (95% confidence interval: 84 to 95) and 91% (95% confidence interval: 86 to 96), respectively. Reoperation occurred in 14 patients (12.6%) at a mean time of 7.8 months (range, 0.5 to 28.6). Re-revision occurred in 12 patients (10.8%) at a mean time of 7.3 months (range, 0.5 to 28.6). Instability was the most common reason for re-revision (4.5%). Neither index approach type, revision approach type, nor any patient-specific risk factors were identified as predictors of re-revision or reoperation in multivariable regression analysis.

CONCLUSIONS

This study demonstrates an acceptable rate of re-revision when aseptic rTHA is performed through an anterior approach, with the most common reason for aseptic re-revision being instability.

Indications, Clinical Outcomes, and Re-Revisions Following Revision Total Hip Arthroplasty - Does Age Matter?

BACKGROUND

Younger age is associated with increased revision incidence following primary total hip arthroplasty, though the association between age and repeat revision following revision total hip arthroplasty (rTHA) has not been described. This study aimed to describe the incidences and indications for subsequent revision (re-revision) following rTHA based on age.

METHODS

Patients undergoing aseptic rTHA from 2011 to 2021 with minimum 1-year follow-up were retrospectively reviewed. Patients were stratified into 3 groups based on age at the time of index rTHA (ie, <55 years, 55 to 74 years, and >74 years). Perioperative characteristics, complications, and re-revisions were compared between groups.

RESULTS

Of 694 included rTHAs, those in the >74 age group were more likely to undergo rTHA for periprosthetic fracture (P < .001) while those in the <55 age group were more likely to undergo rTHA for metallosis/taper corrosion (P = .028). Readmissions (P = .759) and emergency department visits (P = .498) within 90 days were comparable across ages. Rates of re-revision were comparable at 90 days (P = .495), 1 year (P = .443), and 2 years (P = .204). Kaplan-Meier analysis of all-cause re-revision at latest follow-up showed a nonstatistically significant trend toward increasing re-revisions in the <55 and 55 to 74 age groups. Using logistic regressions, smoking and index rTHA for instability were independently associated with re-revision, while age at index surgery was not.

CONCLUSIONS

While indications for rTHA differ across age groups, rates of 2-year re-revision are statistically comparable between groups. Further studies are warranted to understand the association between age, activity, and re-revision rates after 5 years postoperatively.

Does Time to Aseptic Failure After Primary Total Hip Arthroplasty Affect Clinical and Patient-Reported Outcomes?

BACKGROUND

Evidence on the effects of time-to-failure from primary total hip arthroplasty (THA) to aseptic first-revision on clinical results and patient-reported outcome measures (PROMs) is scarce. Therefore, we sought to compare demographics, operative times, lengths of stay, discharge dispositions, 90-day readmissions, re-revision rates, mortalities, and PROMs between early and late aseptic THA revisions.

METHODS

This study is a retrospective review of a prospectively collected institutional database of all elective hip procedures. In total, 572 patients who underwent aseptic revision after primary THA from August 2015 to December 2018 were analyzed. Patients were stratified into either early revision (<3-years; n = 176) or late revision (≥3-years; n = 396) cohorts.

RESULTS

Significantly more patients were revised earlier for bone-related (ie, periprosthetic fractures) (22.7% versus 8.3%) or other various complications (19.9% versus 5.8%), whereas more late revisions were performed to treat implant-related failures (6.8% versus 37.1%), respectively. Operative time was significantly shorter in early versus late revisions (133 versus 157 minutes). A significantly higher delta-change/improvement from baseline/preoperative to 1-year postoperative was found for hip disability and osteoarthritis outcome score physical function (HOOS-PS), veterans-RAND-12 physical and mental components (VR-12-PCS and MCS, respectively) of early revisions. However, HOOS-PS and HOOS-Pain at 1-year of follow-up were significantly worse in early revisions.

CONCLUSION

With exception of operative time, time-to-failure had no significant influence on clinical results. Despite greater improvements on PROMs from preoperative to postoperative, patients undergoing early revisions after primary THA perceive significantly higher levels of pain and worse physical functionality at 1-year of follow-up.

Postoperative Outcomes in Total Hip and Total Knee Arthroplasty for Patients Who Have Multiple Myeloma

BACKGROUND

Advancements in oncologic care have increased the longevity of patients who have multiple myeloma, although outcomes beyond the early postoperative period following total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unknown. This study investigated the influence of preoperative factors on implant survivorship following THA and TKA after a minimum 1-year interval for multiple myeloma patients.

METHODS

Using our institutional database, we identified 104 patients (78 THAs, 26 TKAs) from 2000 to 2021 diagnosed with multiple myeloma before their index arthroplasty by International Classification of Diseases, Ninth and Tenth Revisions (ICD-9 and ICD-10) codes 203.0× and C90.0× and corresponding Current Procedural Terminology (CPT) codes. Demographic data, oncologic treatments, and operative variables were collected. Multivariate logistic regressions assessed variables of interest, and Kaplan-Meier curves were used to estimate implant survival.

RESULTS

There were 9 (11.5%) patients who underwent revision THA after an average time of 1,312 days (range, 14 to 5,763), with infection (33.3%), periprosthetic fracture (22.2%), and instability (22.2%) being the most common indications. Of these patients, 3 (33.3%) underwent multiple revision surgeries. There was 1 (3.8%) patient who underwent revision TKA at 74 days postoperatively for infection. Patients treated with radiotherapy were more likely to require revision THA (odds Rratio (OR): 6.551, 95% confidence interval (CI): 1.148-53.365, P = .045), but no predictors of failure were identified for TKA patients.

CONCLUSION

Orthopaedic surgeons should know that multiple myeloma patients have a relatively high risk of revision, particularly following THA. Accordingly, patients who have risk factors for failure should be identified preoperatively to avoid poor outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Cemented acetabular components combined with trabecular metal augments provide excellent long-term survivorship for severe acetabular bone loss

BACKGROUND

Acetabular bone loss is a challenging problem for revision hip surgeons. This study aimed to explore long-term outcomes of patients who have undergone cemented acetabular revision in conjunction with trabecular metal augmentation and impaction bone grafting in cases with significant segmental bone loss.

METHODS

All patients who underwent cemented acetabular revision requiring impaction bone grafting and trabecular metal augments with a minimum Paprosky score of 2B and minimum follow up of 5 years were identified. Pre- and postoperative WOMAC scores were compared. An assessment of pre- and postoperative hip centre of rotation was performed and compared to native centre of rotation. Immediate postoperative centre of rotation was then compared to radiographs at latest follow up to measure for migration of acetabular components.

RESULTS

42 patients were identified. Mean age was 53 years old with 7 males and 35 female patients. Mean follow-up was 9.5 years. Preoperative WOMAC score was 30 and there was an increase to 90 (p < 0.01) at latest follow-up. No hips were revised for loosening or infection. There was a mean improvement in centre of rotation of 6.80 mm (CI, 4.57-9.03 mm) which was significant (p < 0.00002). There was no change of position of centre of rotation from immediate postoperative radiographs and those at latest follow up (p = 0.3).

CONCLUSIONS

Cemented acetabular components work well in conjunction with trabecular metal augments and impacted bone grafts in reconstructing complex acetabular defects. Together they provide immediate and long-term component stability, with excellent long-term clinical and radiological outcomes.

A finite element study on the interactive effect between the damage of the cup-bone interface and the bone strain of hip implants under various fixation conditions

Interfacial damage has a high impact on the loosening of the acetabular cup. However, monitoring this damage induced by the variations in loading conditions, such as the angle, amplitude, and frequency in vivo, is challenging. In this study, we evaluated the risk of loosening of the acetabular cup due to interfacial damages induced by the deviation in loading conditions and amplitudes. A three-dimensional model of the acetabular cup component was developed, and the interfacial crack growth between the cup and the bone was modeled using a fracture mechanics approach, which simulated the extent of interfacial damage and associated cup displacement. The interfacial delamination mechanism changed with the increasing inclination angle, wherein a fixation angle of 60° exhibited the largest area of contact loss. The compressive strain of embedding the simulated bone at the remaining bonding area accumulated as the lost contact area widened. Such interfacial damages, namely, the growth of the lost contact area and accumulated compressive strain in the simulated bone, promoted both embedding and rotational displacement of the acetabular cup. In the worst case of a fixation angle of 60°, the total displacement of the acetabular cup exceeded the limit of the modified safe zone, suggesting a quantitative risk of dislocation of the acetabular cup induced by the accumulated interfacial damage. Furthermore, nonlinear regression analyses between the degree of displacement of the acetabular cup and the extent of the two types of interfacial damage demonstrated that the interactive effect of the fixation angle with the loading amplitude showed a significant effect on increasing cup displacement. These findings suggest that proper control of the fixation angle during operation is useful in preventing the loosening of the hip joint.

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.

Radiographic Accuracy of Malseated Dual-Mobility Liners Varies Based on Implant Design

BACKGROUND

Dual-mobility constructs have gained popularity to mitigate dislocations after high-risk primary and revision total hip arthroplasties. Contemporary data have indicated that malseating of modular dual-mobility liners occurs in up to 6% of cases. The purpose of this cadaveric-based radiographic study was to determine the ability to accurately determine if modular dual-mobility liners were seated.

METHODS

There were 10 hips (5 cadaveric pelvic specimens) used to implant modular dual-mobility liners of 2 designs. One had a liner that seated flush and the other had an extended rim. There were 20 constructs that were well-seated and 20 constructs were intentionally malseated. A comprehensive series of radiographs was reviewed by 2 blinded surgeons. Statistical analyses included Chi-squared testing, logistic regressions, and kappa statistics.

RESULTS

Radiographic assessment of liner malseating was not accurate with an elevated rim design with misdiagnosis in 40% (16 of 40). The flush design had diagnostic errors in 5% (2 of 40; P = .0002). Logistic regressions demonstrated a significantly higher risk of misdiagnosing a malseated liner in the elevated rim group (odds ratio 13). There were 12 of 16 misdiagnoses in the elevated rim group failing to recognize a malseated liner. Each surgeon had almost perfect agreement for intraobserver reliability for flush designs (k 0.90) and fair agreement in the elevated rim design (k 0.35).

CONCLUSION

A comprehensive series of plain radiographs can reliably detect a malseated modular dual-mobility liner with a flush rim design in 95% of cases. However, elevated rim designs are more difficult to accurately identify malseating on plain radiographs.

Registry Data Show Complication Rates and Cost in Revision Hip Arthroplasty

INTRODUCTION

Revision THA (rTHA) places a burden on patients, surgeons, and health care systems because outcomes and costs are less predictable than primary THA. The purposes of this study were to define indications and treatments for rTHA, quantify risk for readmissions and evaluate the economic impacts of rTHA in a hospital system.

METHODS

The arthroplasty database of a hospital system was queried to generate a retrospective cohort of 793 rTHA procedures, performed on 518 patients, from 2017 to 2019 at 27 hospitals. Surgeons performed chart reviews to classify indication and revision procedure. Demographics, lengths of stay (LOS), discharge dispositions, and readmission data were collected. Analyses of direct costs were performed and categorized by revision type.

RESULTS

46.3% of patients presented for infection. Patients presenting for infection were 5.6 times more likely to have repeat rTHA than aseptic patients. Septic cases (4.3 days) had longer LOS than aseptic ones (2.4) (P < 0.0001). 31% of patients discharged to a skilled nursing facility (SNF). Direct costs were greatest for a two-stage exchange ($37,642), and lowest for liner revision ($8,979). Septic revisions ($17,696) cost more than aseptic revisions ($11,204) (P< 0.0001). The 90-day readmission rate was 21.8%. Septic revisions had more readmissions (13.5%) than aseptic revisions (8.3%).

CONCLUSIONS

Hip revisions, especially for infection, have an increased risk profile and create a major economic impact on hospital systems. Surgeons may use these data to counsel patients on risks of rTHA and advocate for improved reimbursement for the care of revision patients.

Mid-term Results of Revision Total Hip Arthroplasty Using Delta Ceramic-on-Ceramic Bearing

Background

Delta ceramic-on-ceramic (CoC) articulation affords excellent outcomes in primary total hip arthroplasty (THA). However, the safety and reliability of this bearing in revision THA need more evidence. This study aimed to report complications, radiological changes, clinical results, and survivorship of revision THA using Delta CoC articulation at minimum 5-year follow-up.

Methods

We reviewed 118 revision THAs (113 patients: 68 men and 45 women) performed with use of Delta CoC bearing. Their mean age was 58.7 years (range, 30-90 years) and their mean body mass index was 24.6 kg/m² (range, 15.2-32.5 kg/m²). These patients were followed up for 5-12 years (mean, 7.2 years). We evaluated squeak, grinding sensation, ceramic fracture, dislocation, periprosthetic joint infection (PJI), periprosthetic fracture, prosthetic loosening, ceramic wear, osteolysis, modified Harris hip score (mHHS), and survivorship with any reoperation after the revision as the endpoint.

Results

Two patients (1.7%) had grinding sensation, but no patient had ceramic fracture. Reoperations were necessary in 9 hips (7.6%) due to PJIs in 2, stem loosening in 2, cup loosening in 2, recurrent dislocation in 2, and periprosthetic fracture in 1. No hip had measurable wear or osteolysis. The average mHHS improved from 53.3 points before the revision to 82.3 points at the final follow-up. Survivorship was 91.6% (95% confidence interval, 86.3%-96.9%) at 12 years.

Conclusions

The Delta ceramic bearing appeared a reliable option for revision THA, showing encouraging mid-term results with acceptable survivorship and a low complication rate.

Electrospun fibers coated with nanostructured biomimetic hydroxyapatite: A new platform for regeneration at the bone interfaces

Reconstruction of gradient organic/inorganic tissues is a challenging task in orthopaedics. Indeed, to mimic tissue characteristics and stimulate bone regeneration at the interface, it is necessary to reproduce both the mineral and organic components of the tissue ECM, as well as the micro/nano-fibrous morphology. To address this goal, we propose here novel biomimetic patches obtained by the combination of electrospinning and nanostructured bone apatite. In particular, we deposited apatite on the electrospun fibers by Ionized Jet Deposition, a plasma-assisted technique that allows conformal deposition and the preservation in the coating of the target's stoichiometry. The damage to the substrate and fibrous morphology is a polymer-dependent aspect, that can be avoided by properly selecting the substrate composition and deposition parameters. In fact, all the tested polymers (poly(l-lactide), poly(D,l-lactide-co-glycolide, poly(ε-caprolactone), collagen) were effectively coated, and the morphological and thermal characterization revealed that poly(ε-caprolactone) suffered the least damage. The coating of collagen fibers, on the other hand, destroyed the fiber morphology and it could only be performed when collagen is blended with a more resistant synthetic polymer in the nanofibers. Due to the biomimetic composition and multiscale morphology from micro to nano, the poly(ε-caprolactone)-collagen biomimetic patches coated with bone apatite supported MSCs adhesion, patch colonization and early differentiation, while allowing optimal viability. The biomimetic coating allowed better scaffold colonization, promoting cell spreading on the fibers.

Monobloc press-fit cups with large-diameter bearings are safe in revision total hip arthroplasty

BACKGROUND

Instability is a major cause of failure of revision total hip arthroplasty (THA) which can be avoided with the use of monobloc press-fit cups with large diameter heads (LDH).

OBJECTIVE

This consecutive case series analyses whether LDH monobloc components are a safe and clinically beneficial option for revision THA.

METHODS

This consecutive case series includes 47 revision THA with LDH monobloc acetabular cup. Acetabular bone defects were Paprosky type I (42), type IIA (2) and type IIC (3). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and the Patient's Joint Perception (PJP) scores were analysed and a radiographic evaluation for signs of implant dysfunction was performed.

RESULTS

After a mean follow-up of 4.5 years, there were 5 (10.6%) acetabular cup re-revisions: 2 loss of primary fixation and 3 instabilities. Implant survivorship at 4-years was 89.4% (95% CI: 89.3 to 89.5). Recurrent hip dislocation was reported in 1 patient (2.1%) and remains under conservative treatment. The mean WOMAC and FJS were 19.5 (16.8; 0.0 to 58.3) and 57.3 (28.9; 6.3 to 100.0), respectively. Regarding the PJP, 3 (8.8%) patients perceived their hip as natural, 8 (23.5%) as an artificial joint with no restriction, 14 (41.2%) with minor restriction and 9 (26.5%) with major restriction.

CONCLUSION

In cases of revision THA with limited bone loss, press-fit primary fixation with LDH monobloc acetabular components are valuable options that offer excellent mid-term out-comes with low re-revision and joint instability rates.

What Is the Outcome of the First Revision Procedure of Primary THA for Osteoarthritis? A Study From the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Joint arthroplasty registries traditionally report survivorship outcomes mainly on primary joint arthroplasty. The outcome of first revision procedures is less commonly reported, because large numbers of primary procedures are required to analyze a sufficient number of first revision procedures. Additionally, adequate linkage of primary procedures to revisions and mortality is required. When undertaking revision hip surgery, it is important for surgeons to understand the outcomes of these procedures to better inform patients.

QUESTIONS/PURPOSES

Using data from a large national joint registry, we asked: (1) What is the overall rate of revision of the first aseptic revision procedure for a primary THA? (2) Does the rate of revision of the first revision vary by the diagnosis for the first revision? (3) What is the mortality after the first revision, and does it vary by the reason for first revision?

METHODS

The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties, with nearly 100% capture. The analyses for this study were performed on primary THA procedures in patients with a diagnosis of osteoarthritis up to December 31, 2020, who had undergone subsequent revision. We excluded all primary THAs involving metal-on-metal and ceramic-on-metal bearing surfaces and prostheses with exchangeable necks because these designs may have particular issues associated with revisions, such as extensive soft tissue destruction, that are not seen with conventional bearings, making a comparative analysis of the first revision involving these bearing surfaces more complicated. Metal-on-metal bearing surfaces have not been used in Australia since 2017. We identified 17,046 first revision procedures from the above study population and after exclusions, included 13,713 first revision procedures in the analyses. The mean age at the first revision was 71 ± 11 years, and 55% (7496 of 13,713) of the patients were women. The median (IQR) time from the primary procedure to the first revision was 3 years (0.3 to 7.3), ranging from 0.8 years for the diagnosis of dislocation and instability to 10 years for osteolysis. There was some variation depending on the reason for the first revision. For example, patients undergoing revision for fracture were slightly older (mean age 76 ± 11 years) and patients undergoing revision for dislocation were more likely to be women (61% [2213 of 3620]). The registry has endeavored to standardize the sequence of revisions and uses a numerical approach to describe revision procedures. The first revision is the revision of a primary procedure, the second revision is the revision of the first revision, and so on. We therefore described the outcome of the first revision as the cumulative percent second revision. The outcome measure was the cumulative percent revision, which was defined using Kaplan-Meier estimates of survivorship to describe the time to the second revision. Hazard ratios from Cox proportional hazards models, adjusting for age and gender, were performed to compare the revision rates among groups. When possible, the cumulative percent second revision at the longest follow-up timepoint was determined with the available data, and when there were insufficient numbers, we used appropriate earlier time periods.

RESULTS

The cumulative percent second revision at 18 years was 26% (95% confidence interval [CI] 24% to 28%). When comparing the outcome of the first revision by reason, prosthesis dislocation or instability had the highest rate of second revision compared with the other reasons for first revision. Dual-mobility prostheses had a lower rate of second revision for dislocation or instability than head sizes 32 mm or smaller and when compared to constrained prostheses after 3 months. There was no difference between dual-mobility prostheses and head sizes larger than 32 mm. There were no differences in the rate of second revision when first revisions for loosening, periprosthetic fracture, and osteolysis were compared. If cemented femoral fixation was performed at the time of the first revision, there was a higher cumulative percent second revision for loosening than cementless fixation from 6 months to 6 years, and after this time, there was no difference. The overall mortality after a first revision of primary conventional THA was 1% at 30 days, 2% at 90 days, 5% at 1 year, and 40% at 10 years. A first revision for periprosthetic fracture had the highest mortality at all timepoints compared with other reasons for the first revision.

CONCLUSION

Larger head sizes and dual-mobility cups may help reduce further revisions for dislocation, and the use of cementless stems for a first revision for loosening seems advantageous. Surgeons may counsel patients about the higher risk of death after first revision procedures, particularly if the first revision is performed for periprosthetic fracture.Level of Evidence Level III, therapeutic study.

Composite Coatings of Chitosan and Silver Nanoparticles Obtained by Galvanic Deposition for Orthopedic Implants

In this work, composite coatings of chitosan and silver nanoparticles were presented as an antibacterial coating for orthopedic implants. Coatings were deposited on AISI 304L using the galvanic deposition method. In galvanic deposition, the difference of the electrochemical redox potential between two metals (the substrate and a sacrificial anode) has the pivotal role in the process. In the coupling of these two metals a spontaneous redox reaction occurs and thus no external power supply is necessary. Using this process, a uniform deposition on the exposed area and a good adherence of the composite coating on the metallic substrate were achieved. Physical-chemical characterizations were carried out to evaluate morphology, chemical composition, and the presence of silver nanoparticles. These characterizations have shown the deposition of coatings with homogenous and porous surface structures with silver nanoparticles incorporated and distributed into the polymeric matrix. Corrosion tests were also carried out in a simulated body fluid at 37 °C in order to simulate the same physiological conditions. Corrosion potential and corrosion current density were obtained from the polarization curves by Tafel extrapolation. The results show an improvement in protection against corrosion phenomena compared to bare AISI 304L. Furthermore, the ability of the coating to release the Ag⁺ was evaluated in the simulated body fluid at 37 °C and it was found that the release mechanism switches from anomalous to diffusion controlled after 3 h.

The Incidence of Severe Hypercalcaemia-Induced Mental Status Changes in Patients Treated with Antibiotic-Loaded Calcium Sulphate Depot for Orthopaedic Infections

Local application of antibiotics with calcium-containing carrier materials (CCCM) might deliver large quantities of calcium, with some cases of hypercalcaemia reported. The incidence of symptomatic hypercalcaemia was estimated retrospectively in a consecutive, prospective series of patients treated between 10/2006 and 02/2019 with antibiotic-loaded CCCM for various orthopaedic infections. Risk factors were analysed. In the study period, 215 CCCM applications were performed. Two patients (0.9%) developed symptomatic hypercalcaemia. In one case, hypercalcaemia occurred 14 days after a second CCCM application during a staged septic hip revision. In the other case, hypercalcaemia became symptomatic six days after application of vancomycin-loaded CCCM in a component-retaining septic revision hip arthroplasty. In both cases, hypercalcemia was not imputable solely to the CCCM. Prolonged immobilization, renal impairment and other specific risk factors were present. Implantation of a CCCM for local application of antibiotics exposes the patient to large quantities of calcium during dissolution. This might induce symptomatic hypercalcaemia, a potentially life-threatening complication. The observed incidence of symptomatic hypercalcaemia remained rare (<1%). In some patients, compensatory mechanisms might be overwhelmed in the presence of other risk factors. Postoperative monitoring of calcaemia as well as elimination of risk factors is mandatory for all patients treated with CCCM.

Survivorship and Risk Factors for Re-Revision after Aseptic Revision Total Hip Arthroplasty in Patients Aged ≤55 Years

BACKGROUND

There is a relative paucity of literature on the outcomes after revision total hip arthroplasty (rTHA) in young patients. This study reports the survivorship and risk factors for re-revision in patients aged ≤55 years.

METHODS

We identified 354 patients undergoing aseptic nononcologic rTHA at mean follow-up of 5 years after revision, with mean age of 48 years, body mass index of 28 kg/m², and 64% female. Thirty-five (10%) patients underwent at least 1 previous rTHA. The main indications for rTHA included wear/osteolysis (21%), adverse local tissue reaction (21%), recurrent instability (20%), acetabular loosening (16%), and femoral loosening (7%); and included acetabular component-only rTHA in 149 patients (42%), femoral component-only rTHA in 46 patients (13%), both component rTHA in 44 patients (12%), and head/liner exchanges in patients 115 (33%). The Kaplan-Meier method was used to measure survivorship free from re-revision THA, and multivariate regression was used to identify risk factors for re-revision THA.

RESULTS

Sixty-two patients (18%) underwent re-revision THA at the mean time of 2.5 years, most commonly for instability (37%), aseptic loosening (27%), and prosthetic joint infection (15%). The rTHA survivorship from all-cause re-revision and reoperation was 83% and 79% at 5 years, respectively. Multivariate analysis demonstrated that patients undergoing femoral component only (hazard ratio 4.8, P = .014) and head/liner exchange rTHA (hazard ratio 2.5, P = .022) as risk factors for re-revision THA.

CONCLUSION

About 1 in 5 patients aged ≤55 years undergoing rTHA required re-revision THA at 5 years, most commonly for instability. The highest risk group included patients undergoing head/liner exchanges and isolated femoral component revisions.

How long do revised and multiply revised hip replacements last? A retrospective observational study of the National Joint Registry

Background

Hip replacements are common and effective operations but patients that undergo this intervention are at risk of the replacements failing, requiring costly and often complex revision surgery with poorer outcomes than primary surgery. There is paucity of reliable data examining the treatment pathway for hip replacements over the life of the patient in terms of risk of revision and re-revisions. We aim to provide detailed information on the longevity of hip revision surgery.

Methods

We did a retrospective observational registry-based study of the National Joint Registry, using data on hip replacements from all participating hospitals in England and Wales, UK. We included data on all first revisions, with an identifiable primary procedure, with osteoarthritis as the sole indication for the original primary procedure. Kaplan-Meier estimates were used to determine the cumulative probability of revision and subsequent re-revision after primary hip replacement. Analyses were stratified by age and gender, and the influence of time from first to second revision on the risk of further revision was explored.

Findings

Between April 1, 2003, and Dec 31, 2019, there were 29 010 revision hip replacements with a linked primary episode. Revision rates of revision hip replacements were higher in patients younger than 55 years than in older age groups. After revision of primary total hip replacement, 21·3% (95% CI 18·6-24·4) of first revisions were revised again within 15 years, 22·3% (20·3-24·4) of second revisions were revised again within 7 years, and 22·3% (18·3-27·0) of third revisions were revised again within 3 years. After revision of hip resurfacing, 23·7% (95% CI 19·6-28·5) of these revisions were revised again within 15 years, 21·0% (17·0-25·8) of second revisions were revised again within 7 years, and 19·3% (11·9-30·4) of third revisions were revised again within 3 years. A shorter time between revision episodes was associated with earlier subsequent revision.

Interpretation

Younger patients are at an increased risk of multiple revisions. Patients who undergo a revision have a steadily increasing risk of further revision the more procedures they undergo, and each subsequent revision lasts for approximately half the time of the previous one. Although hip replacements are effective for improving pain and function and usually last a remarkably long time, if they are revised, successive revisions are progressively and markedly less successful.

Funding

NIHR Biomedical Research Centre at the University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol, Healthcare Quality Improvement Partnership; and the National Joint Registry.

Changing Surgical Approach From Primary to Revision Total Hip Arthroplasty Is Not Associated With Increased Risk of Dislocation or Re-Revisions

BACKGROUND

No prior studies have examined outcomes based on approach concordance between primary and revision total hip arthroplasty (THA). There is theoretical concern that performing surgery through multiple planes could potentiate dislocation risk. This study aimed to assess the impact of utilizing concordant vs discordant surgical approaches between primary and revision THA on incidence of dislocation, re-revision, reoperation, and nonoperative complications.

METHODS

Between 2000 and 2018, 705 revision THAs were retrospectively identified in patients who underwent primary THA at the same academic center. Surgical approach was determined for primary and revision THA from operative notes with dislocations, re-revisions, reoperations, and complications determined from our total joint registry. Complication rates were compared between those with concordant and discordant surgical approaches. Mean age was 65 years, 50% were female, mean body mass index was 31 kg/m², and mean follow-up was 4 years.

RESULTS

Surgical approach discordance occurred in 97 cases (14%), which was more frequent when the direct anterior approach was used for primary THA (72%, P < .001) compared to lateral (12%) or posterior (10%) approaches. There were no statistically significant differences in the incidence of dislocations, re-revisions, reoperations, and nonoperative complications among those with concordant and discordant approaches for the overall cohort and when analyzed by primary approach (P > .05 for all).

CONCLUSION

Comparable dislocation and complication rates were observed among revision THAs with concordant and discordant approaches between primary and revision THA. These data provide reassurance that changing vs maintaining the surgical approach from primary to revision THA does not significantly increase dislocation or re-revision risk.

LEVEL OF EVIDENCE

IV.

The Utility of Machine Learning Algorithms for the Prediction of Early Revision Surgery After Primary Total Hip Arthroplasty

BACKGROUND

Revision total hip arthroplasty (THA) is associated with increased morbidity, mortality, and healthcare costs due to a technically more demanding surgical procedure when compared with primary THA. Therefore, a better understanding of risk factors for early revision THA is essential to develop strategies for mitigating the risk of patients undergoing early revision. This study aimed to develop and validate novel machine learning (ML) models for the prediction of early revision after primary THA.

METHODS

A total of 7,397 consecutive patients who underwent primary THA were evaluated, including 566 patients (6.6%) with confirmed early revision THA (<2 years from index THA). Electronic patient records were manually reviewed to identify patient demographics, implant characteristics, and surgical variables that may be associated with early revision THA. Six ML algorithms were developed to predict early revision THA, and these models were assessed by discrimination, calibration, and decision curve analysis.

RESULTS

The strongest predictors for early revision after primary THA were Charlson Comorbidity Index, body mass index >35 kg/m2, and depression. The six ML models all achieved excellent performance across discrimination (area under the curve >0.80), calibration, and decision curve analysis.

CONCLUSION

This study developed ML models for the prediction of early revision surgery for patients after primary THA. The study findings show excellent performance on discrimination, calibration, and decision curve analysis for all six candidate models, highlighting the potential of these models to assist in clinical practice patient-specific preoperative quantification of increased risk of early revision THA.

Can machine learning models predict failure of revision total hip arthroplasty?

INTRODUCTION

Revision total hip arthroplasty (THA) represents a technically demanding surgical procedure which is associated with significant morbidity and mortality. Understanding risk factors for failure of revision THA is of clinical importance to identify at-risk patients. This study aimed to develop and validate novel machine learning algorithms for the prediction of re-revision surgery for patients following revision total hip arthroplasty.

METHODS

A total of 2588 consecutive patients that underwent revision THA was evaluated, including 408 patients (15.7%) with confirmed re-revision THA. Electronic patient records were manually reviewed to identify patient demographics, implant characteristics and surgical variables that may be associated with re-revision THA. Machine learning algorithms were developed to predict re-revision THA and these models were assessed by discrimination, calibration and decision curve analysis.

RESULTS

The strongest predictors for re-revision THA as predicted by the four validated machine learning models were the American Society of Anaesthesiology score, obesity (> 35 kg/m²) and indication for revision THA. The four machine learning models all achieved excellent performance across discrimination (AUC > 0.80), calibration and decision curve analysis. Higher net benefits for all machine learning models were demonstrated, when compared to the default strategies of changing management for all patients or no patients.

CONCLUSION

This study developed four machine learning models for the prediction of re-revision surgery for patients following revision total hip arthroplasty. The study findings show excellent model performance, highlighting the potential of these computational models to assist in preoperative patient optimization and counselling to improve revision THA patient outcomes.

LEVEL OF EVIDENCE

Level III, case-control retrospective analysis.

Tribological Characteristics of a-C:H:Si and a-C:H:SiOx Coatings Tested in Simulated Body Fluid and Protein Environment

This paper presents the tribological properties of silicon and oxygen incorporated diamond-like carbon coatings tested in simulated body fluid and bovine serum albumin environments. The tests were performed using a ball-on-disc tribometer with an AISI316L steel counterbody. The wear tracks and wear scars were analyzed using optical microscopy and a nanoindenter. The interaction between the coating and the working environment was analyzed by Fourier transform infrared spectroscopy, whereas changes in the chemical structure before and after the tribological tests were compared with the use of Raman spectroscopy. Our study showed that the tribological parameters are governed by the presence of oxygen rather than the changing concentration of silicon. Both of the spectroscopy results confirm this statement, indicating that coatings with low concentrations of silicon and oxygen appear to be better candidates for biological applications in terms of wear resistance.

MiR-25 overexpression inhibits titanium particle-induced osteoclast differentiation via down-regulation of mitochondrial calcium uniporter in vitro

Background

Mitochondrial calcium uniporter (MCU) is an important ion channel regulating calcium transport across the mitochondrial membrane. Calcium signaling, particularly via the Ca²⁺/NFATc1 pathway, has been identified as an important mediator of the osteoclast differentiation that leads to osteolysis around implants. The present study aimed to investigate whether down-regulation of MCU using microRNA-25 (miR-25) mimics could reduce osteoclast differentiation induced upon exposure to titanium (Ti) particles.

Methods

Ti particles were prepared. Osteoclast differentiation of RAW264.7 cells was induced by adding Ti particles and determined by TRAP staining. Calcium oscillation was determined using a dual-wavelength technique. After exposure of the cells in each group to Ti particles or control medium for 5 days, relative MCU and NFATc1 mRNA expression levels were determined by RT-qPCR. MCU and NFATc1 protein expression was determined by western blotting. NFATc1 activation was determined by immunofluorescence staining. Comparisons among multiple groups were conducted using one-way analysis of variance followed by Tukey test, and differences were considered significant if p < 0.05.

Results

MCU expression was reduced in response to miR-25 overexpression during the process of RAW 264.7 cell differentiation induced by Ti particles. Furthermore, osteoclast formation was inhibited, as evidenced by the low amplitude of calcium ion oscillation, reduced NFATc1 activation, and decreased mRNA and protein expression levels of nuclear factor-κB p65 and calmodulin kinases II/IV.

Conclusions

Regulation of MCU expression can impact osteoclast differentiation, and the underlying mechanism likely involves the Ca²⁺/NFATc1 signal pathway. Therefore, MCU may be a promising target in the development of new strategies to prevent and treat periprosthetic osteolysis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03030-7.

Computer Navigation for Revision Total Hip Arthroplasty Reduces Dislocation Rates

Purpose

Computer navigation in total hip arthroplasty (THA) offers potential for more accurate placement of acetabular components, avoiding impingement, edge loading, and dislocation, all of which can necessitate revision THA (rTHA). Therefore, the use of computer navigation may be particularly beneficial in patients undergoing rTHA. The purpose of this study was to determine if the use of computer-assisted hip navigation reduces the rate of dislocation in patients undergoing rTHA.

Methods

A retrospective review of 72 patients undergoing computer-navigated rTHA between February 2016 and May 2017 was performed. Demographics, indications for revision, type of procedure performed, and incidence of postoperative dislocation were collected for all patients. Clinical follow-up was recorded at 3 months, 1 year and 2 years.

Results

All 72 patients (48% female; 52% male) were included for analysis. The mean age was 70.4 ± 11.2 years and mean BMI was 26.4 ± 5.2 kg/m². 22 of 72 patients (31%) required a rTHA procedure due to instability resulting in dislocation. At 3 months, 1 year, and 2 years, there were no dislocations (0%). There was a significant reduction in dislocation rate after computer-navigated rTHA (0%) relative to that following primary THA in the same patient cohort (31%; p < 0.05).

Conclusion

Our study demonstrates a significant reduction in dislocation rate following rTHA with computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer navigation may help to curtail femoral and acetabular malalignment in rTHA.

Level of Evidence

Level III: retrospective.

Biomaterials and technologies in the management of periprosthetic infection after total hip arthroplasty: An updated review

Although total hip arthroplasty (THA) is considered one of the most efficacious procedures for managing various hip conditions, failures due to different mechanisms are still being reported. Periprosthetic joint infection (PJI) is one of the devastating causes of failure and revision of THA. PJI carries a burden on the patient, the surgeon, and the health-care system. The diagnosis and management of PJIs carry many morbidities and increased treatment costs. The development of PJI is multifactorial, including issues related to the patient’s general condition, the surgeon’s efficiency, surgical technique, and the implants used. Recent advances in the area of diagnosis and predicting PJI as well as introducing new technologies and biomaterials update for the prevention and treatment of PJI. Local implant coatings, advancement in the bearing surfaces technologies, and new technologies such as immunotherapy and bacteriophage therapy were introduced and suggested as contemporary PJI eradication solutions. In this review, we aimed at discussing some of the newly introduced materials and technologies for the sake of PJI control.

Etiology and Complications of Early Aseptic Revision Total Hip Arthroplasty Within 90 Days

BACKGROUND

The etiology, complications, and rerevision risks of early aseptic revision total hip arthroplasty (THA) within 90 days are insufficiently documented.

METHODS

A national insurance claims database (PearlDiver Technologies, Fort Wayne, IN) was queried for patients who underwent unilateral aseptic revision THA within 90 days of the index procedure using administrative codes. Patients who underwent revision for infection, without minimum 2-year follow-up, and younger than 18 years were excluded. This cohort was matched based on gender, age, and Charlson Comorbidity Index to a control group of patients who underwent primary THA without revision within 90 days. Two-year rerevision and 90-day complication rates were recorded. Chi-square and Fisher exact tests were used as appropriate for statistical comparison.

RESULTS

Four hundred two patients met the inclusion criteria for early aseptic revision within 90 days of the index procedure and were matched to the control group. The overall 2-year rerevision rate was higher in the early revision group compared with control group (14.9% vs 2.5%, P < .001). Complications within 90 days occurred more frequently in the early revision group, including blood transfusion (10.2% vs 3.2%, P < .001), deep vein thrombosis (9.0% vs 3.2%, P = .001), and pulmonary embolism (2.74% vs 0.75%, P = .031). The most common reasons for early aseptic revision were dislocation (41.5%), fracture (38.1%), and loosening (17.4%).

CONCLUSION

Early aseptic revision THA is associated with significantly higher 90-day complication rates and 2-year rerevision rates compared with a control group of primary THA without revision. The most common reasons for acute early revision were dislocation, fracture, and mechanical loosening.

LEVEL OF EVIDENCE

Level III.

Removal of an osteointegrated broken uncemented femoral stem after hip arthroplasty-technical note

Broken stems are particularly challenging in revision hip arthroplasty, as no standard extraction instruments fit anymore. Well-integrated uncemented stem remnants can be particularly arduous to remove. Stem fatigue failure is not rare with modular stems. Since these are particularly useful in revision hip arthroplasty, increasing numbers of broken stems are to be expected. Usually applied techniques using cortical fenestration distally to the tip of the stem or using an extended transfemoral approach cause supplementary bone defects impairing reconstruction. We present a relatively simple and reproducible revision technique, using a limited standard approach and only regular orthopedic instruments, to extract the remnants of broken uncemented femoral stems in hip arthroplasty. This technique was applied successfully and without complications in 6 cases, permitting eventually the reimplantation of even shorter stems.

Revisions for Periprosthetic Hip Infections Do Not Fail More Than Revisions for Aseptic Loosening, but Mortality is Higher

BACKGROUND

The influence of the reasons for revision on the outcomes of revision hip arthroplasties is controversial and poorly described. A registry study was designed to compare the revision hips performed for periprosthetic hip infection (PHI) to the revision hips performed for aseptic loosening. The aims of this study were the long-term assessment and comparison of survival rates, reasons for rerevisions, and mortality rates between these two cohorts.

METHODS

By using an arthroplasty registry, revision hips were stratified according to the reasons for revision (aseptic loosening and PHI). Preoperative and intraoperative, demographic and implant-related features were recorded. Survival rates, reasons for revision and mortality rates were assessed and compared.

RESULTS

The two cohorts were homogenous for preoperative and intraoperative parameters, apart from age at revision, time elapsed between THA and revision, bearing surfaces, and head size. At 10 years, the survival rates were similar between the two groups (P = .51). Half of the rerevisions occurred in the first two years in both the groups. The reasons for rerevision were similar: when rerevision for infection was adopted as an end point, the two cohorts showed nonsignificant differences. The mortality rate was statistically higher in the PHI cohort (P .0015, hazard ratio adjusted for age and gender: 1.42).

CONCLUSION

Aseptic and septic revisions achieved similar outcomes at long-terms, rerevisions tended to fail for the same reason for revision. The mortality rate was significantly higher in the septic cohort. These findings are useful to modify and tune the preoperative, intraoperative, and postoperative managements of revisions.

Outcome and Risk Factors Associated with Failures of Isolated Bearing Exchange for Osteolysis in Well-Fixed Cementless Total Hip Arthroplasty

BACKGROUND

It is often challenging to decide whether to revise only the bearing or femoral acetabular component in the setting of progressive osteolysis without component loosening in revision total hip arthroplasty (THA). In this study, we aimed to (1) compare the survivorship of isolated bearing exchange and single/both component revision for patients with periprosthetic osteolysis without component loosening, and (2) identify potential risk factors associated with failures of isolated bearing exchange.

METHODS

A total of 228 consecutive cases of revision THA for progressive osteolysis without component loosening was evaluated in 2 groups: (1) 124 component revision and (2) 104 isolated bearing exchange. The primary outcome was survival, with failure defined as repeat revision or reoperation for any reason. Patient risk factors, such as demographics and medical comorbidities, were also analyzed.

RESULTS

There was no significant difference in survivorship between the component revision group and the bearing exchange group at 10 years (85% vs 82%; P = .89). There was no progression of osteolysis on radiographs at last follow-up for patients with isolated bearing change. Univariate regression modeling demonstrated that renal disease was associated with failure of isolated bearing exchange after revision THA.

CONCLUSION

This study demonstrated that isolated bearing exchange is associated with similar outcomes compared with component revision for aseptic osteolysis without loosening, demonstrating that isolated bearing exchange is a viable option for selected patients with osteolysis in the setting of well-fixed THA components. This provides clinically useful information for surgeons in the surgical treatment of THA patients with wear and osteolysis without component loosening.

Revision Arthroplasty Through the Direct Anterior Approach Using an Asymmetric Acetabular Component

Despite increasing numbers of primary hip arthroplasties performed through the direct anterior approach (DAA), there is a lack of literature on DAA revision arthroplasty. The present study was performed in order to evaluate outcomes and revision rates after revision through the DAA using an asymmetric acetabular component with optional intra- and extramedullary fixation. In a retrospective cohort study, we analyzed prospectively collected data of 57 patients (61 hips, 43 female, 18 male) who underwent aseptic acetabular component revision through the DAA with the abovementioned implant system between January 2015 and December 2017. The mean follow-up was 40 months (12–56). Survival rates were estimated using the Kaplan–Meier method. All complications were documented and functional outcomes were assessed pre- and postoperatively. Kaplan–Meier analysis revealed an estimated five-year implant survival of 97% (confidence interval CI 87–99%). The estimated five-year survival with revision for any cause was 93% (CI 83–98%). The overall revision rate was 6.6% (n = 4). Two patients had to undergo revision due to periprosthetic infection (3.3%). In one patient, the acetabular component was revised due to aseptic loosening four months postoperatively. Another patient suffered from postoperative iliopsoas impingement and was treated successfully by arthroscopic iliopsoas tenotomy. Two (3.3%) of the revised hips dislocated postoperatively. The mean Harris Hip Score improved from 35 (2–66) preoperatively to 86 (38–100) postoperatively (p < 0.001). The hip joint’s anatomical center of rotation was restored at a high degree of accuracy. Our findings demonstrate that acetabular revision arthroplasty through the DAA using an asymmetric acetabular component with optional intra- and extramedullary fixation is safe and practicable, resulting in good radiographic and clinical midterm results.

Barriers to Revision Total Hip Service Lines: A Surgeon's Perspective Through a Deterministic Financial Model

BACKGROUND

Revision THA represents approximately 5% to 10% of all THAs. Despite the complexity of these procedures, revision arthroplasty service lines are generally absent even at high-volume orthopaedic centers. We wanted to evaluate whether financial compensation is a barrier for the development of revision THA service lines as assessed by RVUs.

QUESTIONS/PURPOSES

Therefore, we asked: (1) Are physicians fairly compensated for revision THA on a per-minute basis compared with primary THA? (2) Are physicians fairly compensated for revision THA on a per-day basis compared with primary THA?

METHODS

Our deterministic financial model was derived from retrospective data of all patients undergoing primary or revision THA between January 2016 and June 2018 at an academic healthcare organization. Patients were divided into five cohorts based on their surgical procedure: primary THA, head and liner exchange, acetabular component revision THA, femoral component revision THA, and combined femoral and acetabular component revision THA. Mean surgical times were calculated for each cohort, and each cohort was assigned a relative value unit (RVU) derived from the 2018 Center for Medicaid and Medicare assigned RVU fee schedule. Using a combination of mean surgical time and RVUs rewarded for each procedure, three models were developed to assess the financial incentive to perform THA services for each cohort. These models included: (1) RVUs earned per the mean surgical time, (2) RVUs earned for a single operating room for a full day of THAs, and (3) RVUs earned for two operating rooms for a full day of primary THAs versus a single rooms for a full day of revision THAs. A sixth cohort was added in the latter two models to more accurately reflect the variety in a typical surgical day. This consisted of a blend of revision THAs: one acetabular, one femoral, and one full revision. The RVUs generated in each model were compared across the cohorts.

RESULTS

Compared with primary THA by RVU per minute, in revision THA, head and liner exchange demonstrated a 4% per minute deficit, acetabular component revision demonstrated a 29% deficit, femoral component revision demonstrated a 32% deficit, and full revision demonstrated a 27% deficit. Compared with primary service lines with one room, revision surgeons with a variety of revision THA surgeries lost 26% potential relative value units per day. Compared with a two-room primary THA service, revision surgeons lost 55% potential relative value units per day.

CONCLUSIONS

In a comparison of relative value units of a typical two-room primary THA service line versus those of a dedicated revision THA service line, we found that revision specialists may lose between 28% and 55% of their RVU earnings. The current Centers for Medicare and Medicaid Services reimbursement model is not viable for the arthroplasty surgeon and limits patient access to revision THA specialists.

LEVEL OF EVIDENCE

Level III, economic and decision analysis.

Total Hip Arthroplasty for Femoral Neck Fracture: The Economic Implications of Orthopedic Subspecialty Training

BACKGROUND

Hip fractures have significant economic implications as a result of their associated direct and indirect medical costs. Under alternative payment models, it has become increasingly important for institutions to find avenues by which costs could be reduced while maintaining outcomes in these cases.

METHODS

A multi-institutional retrospective analysis of Medicare patients who underwent total hip arthroplasty (THA) for femoral neck fracture was conducted to assess the impact of fellowship training in adult reconstruction (AR) on the total costs of the 90-day episode of care. Patients were divided into 2 cohorts according to fellowship training status of the operating surgeon: (1) AR-trained and (2) other fellowship training (non-AR). The primary outcome was the total cost of the 90-day episode of care converted to a percentage of the bundled payment target price.

RESULTS

A total of 291 patients who underwent THA for the treatment of a femoral neck fracture were included. The average total cost percentage of the 90-day episode of care was significantly lower for the AR cohort 70.9% (±36.6%) than the non-AR cohort 82.6% (±36.1%) (P < .01). After controlling for baseline demographics in the multivariable logistic regression, the care episodes in which the operating surgeons were AR fellowship-trained were still found to be significantly lower, at a rate of 0.87 times the costs of the non-AR surgeons (95% confidence interval 0.78-0.97, P = .011). In addition, the non-AR cohort exceeded the bundle target price more frequently than the AR cohort, 49 (28.7%) vs 16 (13.3%) (P = .02).

CONCLUSION

In an era of bundled payments, ascertaining factors that may increase the value of care while decreasing the cost is paramount for institutions and policymakers alike. The results presented in this study suggest that in the femoral neck fracture population, surgeons trained in AR achieve lower total costs for the THA episode of care. Furthermore, non-AR fellowship-trained surgeons exceeded the bundled payment target more frequently than the AR surgeons.

Model-Based Roentgen Stereophotogrammetric Analysis to Monitor the Head-Taper Junction in Total Hip Arthroplasty in Vivo-And They Do Move

Model-based Roentgen stereophotogrammetric analysis (RSA) using elementary geometrical shape (EGS) models allows migration measurement of implants without the necessity of additional attached implant markers. The aims of this study were: (i) to assess the possibility of measuring potential head–taper movement in THA in vivo using model-based RSA and (ii) to prove the validity of measured head–taper migration data in vitro and in vivo. From a previous RSA study with a 10 years follow-up, retrospectively for n = 45 patients head–taper migration was calculated as the relative migration between femoral ball head and taper of the femoral stem using model-based RSA. A head–taper migration of 0.026 mm/year can be detected with available RSA technology. In vitro validation showed a total migration of 268 ± 11 µm along the taper axis in a similar range to what has been reported using the RSA method. In vivo, a proof for interchangeable applicability of model-based RSA (EGS) and standard marker-based RSA methods was indicated by a significant deviation within the migration result after 12-month follow-up for all translation measurements, which was significantly correlated to the measured head–taper migration (r from 0.40 to 0.67; p < 0.05). The results identified that model-based RSA (EGS) could be used to detect head–taper migration in vivo and the measured movement could be validated in vitro and in vivo as well. Those findings supported the possibility of applying RSA for helping evaluate the head–taper corrosion related failure (trunnionosis).

Efficiency of Zoledronic Acid in Inhibiting Accelerated Periprosthetic Bone Loss After Cementless Total Hip Arthroplasty in Osteoporotic Patients: A Prospective, Cohort Study

Objective

To investigate the influence of preoperative osteopenia/osteoporosis on periprosthetic bone loss after total hip arthroplasty (THA) and the efficiency of zoledronate (ZOL) treatment in periprosthetic bone preservation.

Methods

This multicenter, prospective cohort study was conducted in four centers between April 2015 and October 2017. Patients were assigned to Normal BMD, Osteopenia, and Osteoporosis+ZOL groups. Patients with osteopenia received daily oral calcium (600 mg/d) and vitamin D (0.5 μg/d), while patients in the Osteoporosis+ZOL group received additional ZOL annually (5 mg/year). Periprosthetic bone mineral density (BMD) in seven Gruen zones, radiographic parameters, Harris hip score, EuroQol 5‐Dimensions (EQ‐5D) score, and BMD in hip and spine were measured within 7 days, 3 months, 12 months postoperation and annually thereafter.

Results

A total of 266 patients were enrolled, while 81 patients that completed the first year follow‐up were involved in the statistical analysis. The mean follow‐up time was 1.3 years. There were significant decreases of mean BMD in total Gruen zones (−4.55%, P < 0.05) and Gruen zone 1 (−10.22%, P < 0.01) in patients with osteopenia during the first postoperative year. Patients in the Osteoporosis+ZOL group experienced a marked increase in BMD in Gruen zone 1 (+16%) at the first postoperative year, which had a significant difference when compared with the Normal BMD group (P < 0.05) and the Osteopenia Group (P < 0.001). Low preoperative BMD in hip and spine was predictive of bone loss in Gruen zone 1 at 12 months after THA in patients with normal BMD (R² = 0.40, P < 0.05).

Conclusions

Patients with osteopenia are prone to higher bone loss in the proximal femur after cementless total hip arthroplasty (THA). ZOL, not solely calcium and vitamin D, could prevent the accelerated periprosthetic bone loss after THA in patients with osteopenia and osteoporosis.

Re-revision total hip arthroplasty: Epidemiology and factors associated with outcomes

INTRODUCTION

The epidemiology of re-revision total hip arthroplasty (THA) is not yet well-understood. We aim to investigate the epidemiology and risk-factors that are associated with re-revision THA.

METHODS

288 revision THA were analyzed between 1/2012 and 12/2013. Patients who underwent two or greater revision THA were included. Hips with first-revision due to periprosthetic joint infection (PJI) were excluded. Failure was defined as reoperation.

RESULTS

51 re-revision patients were available. Mean age was 59.6 (±14.2 years), 32 (67%) females, average BMI of 28.8 (±5.4), and median ASA 2 (23; 55%). The most common re-revision indications were acetabular component loosening (15; 29%), PJI (13; 25%) and instability (9; 18%). The most common indications for first revision in the re-revision population were acetabular component loosening (11; 27%), polyethylene wear (8; 19%) and instability (8; 19%). There was an increased risk of re-revision failure if the re-revision involved exchanging only the head and polyethylene liner (RR = 1.792; p = 0.017), instability was the first-revision indication (RR = 3.000; p < 0.001), and instability was the re-revision indication (RR = 1.867; p = 0.038). If isolated femoral component revision was indicated during the re-revision, there was a decreased risk of failure (RR = 0.268, p = 0.046). 1-year re-revision survival was 54% (23/43).

DISCUSSION

Acetabular component loosening, instability, and PJI were the most common indications for re-revision. Revision due to instability is a recurrent problem that leads to re-revision failure. There was a higher infection rate in the re-revision population compared to published revision PJI. A better understanding of the indications and patient factors that are associated with re-revision failures can help align surgeon and patient expectations in this challenging population.

High survivorship of highly cross-linked polyethylene in revision Total hip Arthroplasty: a minimum 10-year follow-up study

Purpose

Highly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation. However, few long-term data on revision total hip arthroplasty (THA) using highly cross-linked polyethylene liners are available. The objective of this study was to determine long-term outcomes of a highly cross-linked polyethylene liner in revision THA.

Materials & methods

We evaluated 63 revision THAs performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up. Thus, the final study cohort consisted of 50 patients (50 hips), including 26 males and 24 females with a mean age of 53 years (range, 27–75 years). Mean follow-up was 11 years (range, 10–14 years).

Results

The mean Harris hip score improved from 44 points preoperatively to 85 points at the final follow-up. No radiographic evidence of osteolysis was found in any hip. The mean rate of polyethylene liner wear was 0.029 mm/year (range, 0.003 to 0.098 mm/year). A total of 5 hips (10%) required re-revision arthroplasty, including one cup loosening, one recurrent dislocation, and three deep infections. Kaplan-Meier survivorship with an end point of re-revision for any reason was 91.1% and for aseptic cup loosening was 97.9% at 11 years.

Conclusion

At a minimum of 10 years, the highly cross-linked polyethylene liners showed excellent clinical performance and implant survivorship, and were not associated with osteolysis in our patients with revision THAs.

Simulated Performance of a Xenohybrid Bone Graft (SmartBone®) in the Treatment of Acetabular Prosthetic Reconstruction

Total hip arthroplasty (THA) is a surgical procedure for the replacement of hip joints with artificial prostheses. Several approaches are currently employed in the treatment of this kind of defect. Overall, the most common method involves using a quite invasive metallic support (a Burch-Schneider ring). Moreover, valid alternatives and less invasive techniques still need to be supported by novel material development. In this work, we evaluated the performance of SmartBone®, a xenohybrid bone graft composed of a bovine bone matrix reinforced with biodegradable polymers and collagen, as an effective support in acetabular prosthesis reconstruction. Specifically, the material's mechanical properties were experimentally determined (E = ~1.25 GPa, Ef = ~0.34 GPa, and Et = ~0.49 GPa) and used for simulation of the hip joint system with a SmartBone® insert. Moreover, a comparison with a similar case treated with a Burch-Schneider ring was also conducted. It was found that it is possible to perform THA revision surgeries without the insertion of an invasive metal support and it can be nicely combined with SmartBone®'s osteointegration characteristics. The material can withstand the loads independently (σmax = ~12 MPa) or be supported by a thinner titanium plate in contact with the bone in the worst cases. This way, improved bone regeneration can be achieved.

A dedicated revision total knee service: a surgeon’s perspective

AIMS

Revision total knee arthroplasty (rTKA) accounts for approximately 5% to 10% of all TKAs. Although the complexity of these procedures is well recognized, few investigators have evaluated the cost and value-added with the implementation of a dedicated revision arthroplasty service. The aim of the present study is to compare and contrast surgeon productivity in several differing models of activity.

MATERIALS AND METHODS

All patients that underwent primary or revision TKA from January 2016 to June 2018 were included as the primary source of data. All rTKA patients were categorized by the number of components revised (e.g. liner exchange, two or more components). Three models were used to assess the potential surgical productivity of a dedicated rTKA service : 1) work relative value unit (RVU) versus mean surgical time; 2) primary TKA with a single operating theatre (OT) versus rTKA with a single OT; and 3) primary TKA with two OTs versus rTKA with a single OT.

RESULTS

In total, 4570 procedures were performed: 4128 primary TKAs, 51 TKA liner exchanges, and 391 full rTKAs. Surgical time was significantly different between the primary TKA, liner exchange, and rTKA cohorts (100.6, 97.1, and 141.7 minutes, respectively; p < 0.001). Primary TKA yielded a mean of 7.1% more RVU/min per procedure than rTKA. Our one-OT model demonstrated that primary TKA (n = 4) had a 1.9% RVU/day advantage over rTKA (n = 3). If two OTs are used for primary TKA (n = 6), the outcome strongly favours primary TKA by an added 34.6% RVUs/day.

CONCLUSION

Our results suggest that a dedicated rTKA service would lead to lower surgeon remuneration based on the current RVU paradigm. Revision arthroplasty specialists may need additional or alternative incentives to promote the development of a dedicated revision service. Through such an approach, healthcare organizations could enhance the quality of care provided, but surgeon productivity measures would need to be adjusted to reflect the burden of these cases. Cite this article: Bone Joint J 2019;101-B:675-681.

A systematic review of the causes of failure of Revision Total Hip Arthroplasty

This study reviewed literature published in the last 10 years to investigate the reasons for revision failure. A total of 9952 revisions were identified and it was determined that the number one cause of failure was aseptic loosening (23.19%), followed by instability (22.43%) and infection (22.13%). Further analysis of applicable revisions investigated BMI and age at the failure rates. The rate of rerevision in obese patients was markedly higher (p < 0.01) compared to non-obese patients and individuals receiving a revision THA under the age of 55 are at a higher risk of rerevision (p < 0.01).

What Is the Association Between Hospital Volume and Complications After Revision Total Joint Arthroplasty: A Large-database Study

BACKGROUND

Studies of primary total joint arthroplasty (TJA) show a correlation between hospital volume and outcomes; however, the relationship of volume to outcomes in revision TJA is not well studied.

QUESTIONS/PURPOSES

We therefore asked: (1) Are 90-day readmissions more likely at low-volume hospitals relative to high-volume hospitals after revision THA and TKA? (2) Are in-hospital and 90-day complications more likely at low-volume hospitals relative to high-volume hospitals after revision THA and TKA? (3) Are 30-day mortality rates higher at low-volume hospitals relative to high-volume hospitals after revision THA and TKA?

METHODS

Using 29,948 inpatient stays undergoing revision TJA from 2008 to 2014 in the Statewide Planning and Research Cooperative System (SPARCS) database for New York State, we examined the relationship of hospital revision volume by quartile and outcomes. The top 5 percentile of hospitals was included as a separate cohort. Advantages of the SPARCS database include comprehensive catchment of all cases regardless of payer, and the ability to track each patient across hospital admissions at different institutions within the state. The outcomes of interest included 90-day all-cause readmission rates and 30- and 90-day reoperation rates, postoperative complication rates, and 30-day mortality rates. The initial cohort that met the MS-DRG and ICD-9 criteria consisted of 30,354 inpatient stays for revision hip or knee replacements. Exclusions included patients with a missing patient identifier (n = 221), missing admission or discharge dates (n = 5), and stays from hospitals that were closed during the study period (n = 180). Our final analytic cohort comprised 29,948 inpatient stays for revision hip and knee replacements from 25,977 patients who had nonmissing data points for the variables of interest. Outcomes were adjusted for underlying hospital, surgeon, and patient confounding variables. The analytic cohort included observations from 25,977 patients, 138 hospitals, 929 surgeons, 14,130 revision THAs, 11,847 revision TKAs, 15,341 female patients (59% of cohort).

RESULTS

Patients had lower all-cause 90-day readmission rates in the highest 5th percentile by volume hospitals relative to all other lower hospital volume categories. Reoperation rates within the first 90 days, however, were not different among volume categories. All-cause 90-day readmissions were higher in the quartile 4 hospitals excluding the top 5th percentile (17%) versus the top 5th percentile by volume hospitals (12%) (odds ratio [OR]: 1.3; 95% confidence interval [CI], 1.0-1.5; p = 0.030). All-cause 90-day readmissions were higher in the quartile 3 hospitals (18%) relative to the top 5 percentile by volume hospitals (12%) (OR: 1.5; 95% CI, 1.2-1.9; p < 0.001). All-cause 90-day readmissions were higher in quartile 2 hospitals (18%) relative to the top 5 percentile by volume hospitals (12%) (OR: 1.4; 95% CI, 1.1-1.8; p = 0.010). All-cause 90-day readmissions were higher in quartile 1 hospitals (21%) versus the top 5 percentile by volume hospitals (12%) (OR: 1.6; 95% CI, 1.1-2.3; p = 0.010). Postoperative complication rates were higher among only the quartile 1 hospitals compared with institutions in each higher-volume category after revision TJA. The odds of 90-day complications compared with quartile 1 hospitals were 0.49 (95% CI, 0.33-0.72; p = 0.010) for quartile 2, 0.60 (95% CI, 0.40-0.88; p = 0.010) for quartile 3, 0.43 (95% CI, 0.28-0.64; p = 0.010) for quartile 4 excluding top 5 percentile, and 0.36 (95% CI, 0.22-0.59; p = 0.010) for the top 5 percentile of hospitals. There does not appear to be an association between 30-day mortality rates and hospital volume in revision TJA. The odds of 30-day mortality compared with quartile 1 hospitals were 0.54 (95% CI, 0.20-1.46; p = 0.220) for quartile 2, 0.75 (95% CI, 0.30-1.91; p = 0.550) for quartile 3, 0.57 (95% CI, 0.22-1.49; p = 0.250) for quartile 4 excluding top 5 percentile, and 0.61 (95% CI, 0.20-1.81; p = 0.370) for the top 5 percentile of hospitals.

CONCLUSIONS

These findings suggest that regionalizing revision TJA services, or concentrating surgical procedures in higher-volume hospitals, may reduce early complications rates and 90-day readmission rates. Disadvantages of regionalization include reduced access to care, increased patient travel distances, and possible capacity issues at receiving centers. Further studies are needed to evaluate the benefits and negative consequences of regionalizing revision TJA services to higher-volume revision TJA institutions.

LEVEL OF EVIDENCE

Level III, therapeutic study.

A Review on Ionic Substitutions in Hydroxyapatite Thin Films: Towards Complete Biomimetism

Plasma sprayed coatings composed of stoichiometric hydroxyapatite have been extensively used to improve integration of metallic implants in the host bone, as hydroxyapatite (HA) is normally regarded as similar to the mineralized phase of bone. However, these coatings exhibited several drawbacks that limited their success. On the one hand biological apatite is a carbonated-HA, containing significant amounts of foreign ions, having low crystallinity and a small crystals size. This means that it differs from stoichiometric HA in terms of composition, stoichiometry, crystallinity degree, crystal size/morphology and, as a direct consequence, solubility, and ions release in the peri-implant environment. On the other hand, thick plasma sprayed coatings can undergo cracking and delamination and are scarcely uniform. For these reasons, research is pushing into two directions: (i) Increasing the similarity of apatite coatings to real bone, and (ii) exploring deposition by alternative plasma assisted techniques, allowing to achieve thin films, and having superior adhesion and a better control over the coating composition. In this article, we review the latest advances in the field of plasma-assisted deposition of ion-substituted hydroxyapatite thin films, highlighting the state of the art, the limitations, potentialities, open challenges, and the future scenarios for their application.

Risk Factors for Readmission Following Revision Total Hip Arthroplasty in Patients Undergoing Surgery for Noninfective Causes

Introduction

Readmission following revision orthopedic surgery imposes tremendous costs due to the increased length of stay, procedure complexity, and revision surgery. Following revision total hip arthroplasty, as many as one in five patients are readmitted postoperatively. Readmissions cost the federal government $17.4 billion annually. The purpose of this study was to identify risk factors for unplanned readmission following revision total hip arthroplasty.

Methods

This was a retrospective case series review of randomized revision total hip arthroplasties (THA) patients between 2008 and 2018. Exclusions were as follows: outside hospital revisions, staged revisions, revisions for infection, and bilateral revisions. Data were collected by manual chart review. Readmissions were tracked from discharge until the final follow-up.

Results

A total of 61 patients and 85 revision THAs were analyzed. Nineteen patients (31.1%) were readmitted; 31.6% of the readmitted patients had a coronary artery disease compared to 6.5% of non-readmitted patients. Readmission was also associated with obesity, former smokers, and hypertension. Also, the mean duration of follow-up was 26.5 months for readmitted patients as compared to 8.96 for non-readmitted patients.

Conclusion

Obesity, former tobacco use, younger age, coronary artery disease (CAD), and hypertension were associated with readmission. The medical optimization of patients with these risk factors prior to surgery could significantly lower costs relative to revision THA.

Biological and osseointegration capabilities of hierarchically (meso-/micro-/nano-scale) roughened zirconia

PURPOSE

Zirconia is a potential alternative to titanium for dental and orthopedic implants. Here we report the biological and bone integration capabilities of a new zirconia surface with distinct morphology at the meso-, micro-, and nano-scales.

METHODS

Machine-smooth and roughened zirconia disks were prepared from yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), with rough zirconia created by solid-state laser sculpting. Morphology of the surfaces was analyzed by three-dimensional imaging and profiling. Rat femur-derived bone marrow cells were cultured on zirconia disks. Zirconia implants were placed in rat femurs and the strength of osseointegration was evaluated by biomechanical push-in test.

RESULTS

The rough zirconia surface was characterized by meso-scale (50 µm wide, 6-8 µm deep) grooves, micro-scale (1-10 µm wide, 0.1-3 µm deep) valleys, and nano-scale (10-400 nm wide, 10-300 nm high) nodules, whereas the machined surface was flat and uniform. The average roughness (Ra) of rough zirconia was five times greater than that of machined zirconia. The expression of bone-related genes such as collagen I, osteopontin, osteocalcin, and BMP-2 was 7-25 times upregulated in osteoblasts on rough zirconia at the early stage of culture. The number of attached cells and rate of proliferation were similar between machined and rough zirconia. The strength of osseointegration for rough zirconia was twice that of machined zirconia at weeks two and four of healing, with evidence of mineralized tissue persisting around rough zirconia implants as visualized by electron microscopy and elemental analysis.

CONCLUSION

This unique meso-/micro-/nano-scale rough zirconia showed a remarkable increase in osseointegration compared to machine-smooth zirconia associated with accelerated differentiation of osteoblasts. Cell attachment and proliferation were not compromised on rough zirconia unlike on rough titanium. This is the first report introducing a rough zirconia surface with distinct hierarchical morphology and providing an effective strategy to improve and develop zirconia implants.