Clinical Outcomes of Offset Stem Couplers with or without Cone Augmentation in Revision Total Knee Arthroplasty.

Intramedullary stems are often required in patients undergoing revision total knee arthroplasty (rTKA) to achieve stable fixation. Significant bone loss may require the addition of a metal cone to maximize fixation and osteointegration. The purpose of this study was to investigate clinical outcomes in rTKA using different fixation techniques. We conducted a single-institution retrospective review of all patients who received a tibial and femoral stem during rTKA between August 2011 and July 2021. Patients were separated into three cohorts based on fixation construct: press-fit stem with an offset coupler (OS), fully cemented straight (CS) stem, and press-fit straight (PFS) stem. A subanalysis of patients who received tibial cone augmentation was also conducted. A total of 358 patients who underwent rTKA were included in this study, of which 102 (28.5%) had a minimum 2-year follow-up and 25 (7.0%) had a minimum 5-year follow-up. In the primary analysis, 194 patients were included in the OS cohort, 72 in the CS cohort, and 92 in the PFS cohort. When stem type alone was considered, there was no significant difference in rerevision rate (p = 0.431) between cohorts. Subanalysis of patients who received augmentation with a tibial cone demonstrated that OS implants led to significantly higher rates of rerevision compared with the other two stem types (OS: 18.2% vs. CS: 2.1% vs. PFS: 11.1%; p = 0.037). The findings of the present analysis demonstrate that CS and cones in rTKA may provide more reliable long-term outcomes compared with press-fit stems with OS. LEVEL III EVIDENCE: Retrospective Cohort Study.

Does experience with total knee arthroplasty in morbidly obese patients effect surgical outcomes.

INTRODUCTION: Literature examining the risks, benefits, and potential complications of TKA in morbidly obese patients is conflicting. Surgeons with more experience performing TKA on morbidly obese patients may generate superior outcomes. This study sought to assess whether complication rates and implant survivorship in morbidly obese TKA patients varies between high (HV) and low (LV) volume surgeons. METHODS: A retrospective review was performed to include all morbidly obese (BMI ≥ 40) patients that underwent primary TKA between January 2016 and July 2021 at our high-volume center. Demographics and clinical outcomes were collected and compared between surgeons with a higher morbidly obese TKA volume (> 10 annual cases) and surgeons with a lower morbidly obese TKA volume. RESULTS: A total of 964 patients (HV 91 [9.4%], LV 873 [90.6%]) were identified. The HV surgeon and LV surgeons had an average annual volume of 15.3 and 5.2 cases, respectively. The average BMI for the HV and LV cohorts were 44.5 ± 3.7 and 44.0 ± 3.6, respectively (p = 0.160). The HV surgeon had significantly lower operative times (105.7 ± 17.4 vs. 110.7 ± 29.6 min, p = 0.018), and a lower 90-day minor complication rate (0.0% vs. 4.7%, p = 0.035). For patients with at least 2-year follow-up, all-cause revision (3.4% vs. 12.5%, p = 0.149) and revision due to PJI (0.0% vs. 5.8%, 0.193) rates were numerically lower in the HV cohort. Improvements in KOOS, JR and VR-12 scores were similar at 3-month and 1-year follow-up. Freedom from all-cause revision (HV: 96.6% vs. LV: 80.4%, p = 0.175) and revision due to PJI (HV: 100.0% vs. LV: 93.6%, p = 0.190, p = 0.190) at latest follow-up did not statistically differ between groups. CONCLUSION: The HV surgeon had significantly lower operative time and 90-day minor complication rates and numerically lower all-cause revision and revision due to PJI rates when performing TKA in morbidly obese patients. Surgeon's experience may affect surgical outcomes after TKA in morbidly obese patients. LEVEL OF EVIDENCE: III.

Impact of a Novel Navigational Technology on Short-Term Patient Outcomes Following Total Knee Arthroplasty A Propensity Matched Cohort Study.

PURPOSE: The use of intraoperative technology is increasing among orthopedic surgeons in the United States. However, there is continued debate as to whether intraoperative technologies provide clinical benefits in patients undergoing total knee arthroplasty (TKA). This study sought to determine whether the use of a novel intraoperative navigation technology produces equivalent or superior short-term outcomes compared to conventional technique. METHODS: Fifty-nine consecutive patients underwent primary TKA with a novel imageless intraoperative navigational technology between October 2019 and January 2020 at a single, urban, orthopedic specialty hospital. A 1:1 cohort propensity matching was performed with patients with similar demographics who underwent primary TKA without the use of technology. Demographics, clinical data, as well as preoperative and 3-month Knee Injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS, JR) scores were collected. Demographic differences, clinical data, and mean KOOS, JR scores were assessed using chi-squared analysis for categorical variables and independent sample t-test for continuous variables. RESULTS: Upon 1:1 cohort matching, patients in both the navigational cohorts and non-navigational cohorts were statistically similar demographically. Length of stay (2.11 vs. 1.71 days; p = 0.108), surgical time (108.89 vs. 101.19 minutes, p = 0.066), discharge disposition (p = 0.675), 90- day readmissions (4 vs. 4, p = 0.999), and 90-day reoperations (2 vs. 2, p = 0.999) did not statistically differ between the two matched cohorts. Additionally, KOOS, JR scores evaluated between the two cohorts preoperatively (46.06 vs. 45.17, p = 0.836) and at 3-month follow-up (57.63 vs. 55.06, p = 0.580) were similar. CONCLUSION: This study demonstrates that the use of this novel intraoperative navigational technology yields similar short-term TKA results when compared to conventionally performed TKA. Further studies are required to validate new technologies and determine their effect on long-term clinical and patient-reported outcomes.

An Analysis of Component Positioning, Offset, and Limb Length Restoration in Computer-Assisted Hip Resurfacing Arthroplasty.

INTRODUCTION: Hip resurfacing arthroplasty (HRA) is a surgical option with positive outcomes at medium-term follow-up for young, active patients with osteoarthritis. However, early failures of HRA often occur due to improper implant placement. The purpose of this study was to assess the utility of computer-assisted navigation in the effort to optimize implant positioning following HRA. MATERIALS AND METHODS: A retrospective analysis of 262 consecutive HRAs at a single institution was performed. Radiographic analysis included measurements of cup inclination and anteversion, leg length restoration (LLR), and offset. Cup position was evaluated based on placement within Lewinnek parameters and the surgeon's preferred anteversion (10° to 20°). Chi-squared and unpaired Student's t-test were performed for all categorical and continuous variables, respectively. RESULTS: One hundred fifty-six cases were performed using conventional technique and 106 cases used computernavigation. Computer-assisted HRA (caHRA) had a longer mean surgical time (129 vs. 110 minutes; p < 0.001) but shorter average LOS (1.1 vs. 1.5 days; p < 0.001). Cup position was within the surgeon-preferred target zone in 47% of caHRA versus 22% of conventional HRA (p = 0.0001). Cup position fell within the Lewinnek safe zone in 86% of caHRA versus 60% of conventional HRA (p < 0.001). Global offset was reduced by a mean of 6.4 mm in caHRA versus 8.4 mm (p = 0.036). No differences in rates of complication (p = 0.406), reoperation (p = 1.00), or 90-day readmission (p = 0.568) were observed. CONCLUSION: Computer-assisted technology in HRA allows for comparable clinical outcomes to conventional technique. Cup position accuracy and precision is improved by computer navigation in HRA.

Multiply revised TKAs have worse outcomes compared to index revision TKAs.

Aims: Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised. Methods: This retrospective, observational study reviewed patients who underwent unilateral, aseptic rTKA at an academic orthopaedic speciality hospital between June 2011 and April 2020 with > one-year of follow-up. Patients were dichotomized based on whether this was their first revision procedure or not. Patient demographics, surgical factors, postoperative outcomes, and re-revision rates were compared between the groups. Results: A total of 663 cases were identified (486 index rTKAs and 177 multiply revised TKAs). There were no differences in demographics, rTKA type, or indication for revision. Multiply revised patients had significantly longer rTKA operative times (p < 0.001), and were more likely to be discharged to an acute rehabilitation centre (6.2% vs 4.5%) or skilled nursing facility (29.9% vs 17.5%; p = 0.003). Patients who had been multiply revised were also significantly more likely to have subsequent reoperation (18.1% vs 9.5%; p = 0.004) and re-revision (27.1% vs 18.1%; p = 0.013). The number of previous revisions did not correlate with the number of subsequent reoperations (r = 0.038; p = 0.670) or re-revisions (r = -0.102; p = 0.251). Conclusion: Multiply revised TKA had worse outcomes, with higher rates of facility discharge, longer operative times, and greater reoperation and re-revision rates compared to index rTKA.

Patellar Component Design Does Not Impact Clinical Outcomes in Primary Total Knee Arthroplasty.

BACKGROUND: Round or oval implants are used in patellar resurfacing during total knee arthroplasty (TKA). However, whether component geometry affects clinical outcomes is unclear. This study aimed to determine if one implant shape conferred superior outcomes to the other. METHODS: A retrospective review of primary TKA cases performed from 2016 to 2020 was conducted at an urban, tertiary academic center. Four hundred consecutive, primary TKAs were included in these analyses. Cases were included if a surgeon used the round design then oval design for fifty consecutive cases. Baseline demographic data and radiographic measurements were assessed. Surgical data, reasons for revision, and patient-reported outcome measures were analyzed. Independent samples t-test and chi-square tests were used to compare means and proportions. There were no demographic differences between the cohorts. RESULTS: Postoperative patellar tilt was statistically different between the cohorts. Sixteen patients required revision surgery; however, revision rates did not differ between the cohorts. Of the 9 rounds, 1 button was revised for infection. Of the 7 ovals, 1 button was revised for infection and 1 for loosening. Veterans RAND 12 Physical Component Score at 3 months postoperatively was higher for the round cohort, but no differences were observed at 1 year. CONCLUSION: While radiographic patellar tilt was significantly different between the cohorts, there was no clinical correlation in outcomes at 3 months or 1 year postoperatively. Longer-term follow-up studies are needed to evaluate the implications of patellar component design on outcomes and function. Nevertheless, the current study affirms that both designs are clinically equivalent which should be used to guide clinical decision-making. LEVEL III EVIDENCE: Retrospective Cohort.

The learning curve associated with imageless navigation in total knee arthroplasty.

INTRODUCTION: Computer-assisted navigation systems (CAS) are increasingly being integrated into total knee arthroplasty (TKA) procedures, but perceptions of associated learning curve and increased operative time continue to curtail uptake. Newer-generation navigational systems aim to streamline integration into surgical workflow to mitigate increases in operative time. Here, we assess the impact of a novel imageless CAS on operative time for TKA. METHODS: A retrospective analysis of prospectively collected data of a cohort of patients undergoing primary unilateral TKA with one of three surgeons between October 2019 and March 2020 was conducted. Consecutive cases using a novel imageless CAS were included in analysis. For each surgeon, average operative time was recorded and compared in sequential five-case cohorts to average operative time for the same procedure performed conventionally using a two-tailed t test. RESULTS: Average conventional operative times were 95.9 ± 15.0, 86.6 ± 13.7, and 116.9 ± 25.1 min for the three surgeons. Initial CAS-assisted operative times increased to 107.0 ± 9.8 (p = 0.07) and 102.4 ± 13.2 (p = 0.06) min for Surgeons 1 and 2 and decreased to 113.2 ± 9.8 min (p = 0.52) for Surgeon 3. Most recent CAS-assisted operative times were 94.8 ± 13.9 (p = 0.88), 88.7 ± 15.3 (p = 0.84), and 104.8 ± 13.2 (p = 0.12) min as compared to pre-CAS. Absolute differences for the most recent navigated procedures ranged from 12.1 min faster to 2.0 min slower. CONCLUSION: The learning curve for TKA navigation may be as few as 10 cases, and any associated increases in operative time may be transient and non-significant. Moreover, navigation may ultimately speed operative time, perhaps as the result of enhanced intraoperative assessment of alignment.

Novel metaphyseal porous titanium cones allow favorable outcomes in revision total knee arthroplasty.

INTRODUCTION: Loosening and migration are common modes of aseptic failure following complex revision total knee arthroplasty (rTKA). Metaphyseal cones allow surgeons to negotiate the loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing rTKA utilizing a novel metaphyseal cone system with stems of variable length and fixation methods. METHODS: This two-center retrospective study examined all patients who underwent rTKA with a novel porous, titanium tibial or femoral cone in combination with a stem of variable length and fixation who had a minimum follow-up of 2-years. Outcome analysis was separated into tibial and femoral cones as well as the stem fixation method (hybrid vs. fully cemented). RESULTS: Overall, 123 patients who received 156 cone implants were included (74 [60.2%] tibial only, 16 [13.0%] femoral only, and 33 [26.8%] simultaneous tibial and femoral) with a mean follow-up of 2.76 ± 0.66 years. At 2-years of follow-up the total cohort demonstrated 94.3% freedom from all-cause re-revisions, 97.6% freedom from aseptic re-revisions, and 99.4% of radiographic cone osteointegration. All-cause revision rates did not differ between stem fixation techniques in both the tibial and femoral cone groups. CONCLUSION: The use of a novel porous titanium femoral and tibial metaphyseal cones combined with stems in patients with moderate to severe bone defects undergoing complex revision total knee arthroplasty confers excellent results independent of stem fixation technique. LEVEL OF EVIDENCE: IV, case series.

Does Obesity Impact Outcomes of Total Knee Arthroplasty When Treated by High-Volume Surgeons? A Propensity-Matched Analysis From a High-Volume Urban Center.

BACKGROUND: The impact of morbid obesity (MO) on outcomes following total knee arthroplasty (TKA) when performed by high-volume (HV) surgeons has not been investigated. This study aimed to assess complication rates and implant survivorship in MO patients operated on by HV surgeons. METHODS: Patients undergoing primary, elective TKA between June 2011 and May 2022 with a HV surgeon (top 25% surgeons by the number of primary TKAs per year) were retrospectively reviewed. Patients were stratified by body mass index (BMI) into 3 groups: BMI ≥40 (MO), 30≤ BMI <40 (non-morbidly obese), and BMI <30 (nonobese) and 1:1:1 propensity matched based on baseline characteristics. Of the 12,132 patients evaluated, 1,158 were included in final matched analyses (386 per group). The HV surgeons performed a median of 104 TKAs annually (range, 90-173). RESULTS: The MO patients had significantly longer surgery duration (P = .006) and hospital lengths of stay (P < .001). The 90-day postoperative complications (P = .38) and readmission rates (P = .39) were comparable between groups. Rates of all-cause, septic and aseptic revision were similar between groups at two-year (P = .30, P = .15, and P = .26, respectively) and the latest follow-up (P = .36, P = .52, and P = .38, respectively). Improvement in Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) scores at 6 months (P = .049) and one year (P = .015) was significantly higher in MO patients. CONCLUSION: Clinical outcomes and complication rates following TKA by HV surgeons are comparable regardless of obesity status. The MO patients may benefit from referral to experienced surgeons to minimize procedural risks and improve outcomes. LEVEL OF EVIDENCE: III.

The Cam-Post Dislocation in Posterior-Stabilized Total Knee Arthroplasty A Case Series.

Cam-post dislocations are a unique complication of total knee arthroplasty (TKA) designs that utilize a cam-post mechanism, representing an extreme form of deep flexion instability. They are rare complications and are poorly defined in the existing literature. The purpose of this case study is to present a series of six cam-post dislocation cases to improve understanding of this complication and its mechanism, presentation, and available treatment options. All patients experienced cam-post dislocations after a deep flexion moment that were identified clinically and confirmed radiographically. Affected implants included both primary and revision components and all utilized a cam-post mecha- nism. Three patients underwent revision surgery whereas the remaining three were treated with closed reduction only. Cam-post dislocations are rare complications of posterior- stabilized TKA that should be understood and recognized by adult reconstruction surgeons. Closed reduction may be achieved with hyperflexion and anterior drawer or with hyperextension, but these patients may ultimately require a revision procedure.

The use of imageless navigation to quantify cutting error in total knee arthroplasty.

PURPOSE: Navigated total knee arthroplasty (TKA) improves implant alignment by providing feedback on resection parameters based on femoral and tibial cutting guide positions. However, saw blade thickness, deflection, and cutting guide motion may lead to final bone cuts differing from planned resections, potentially contributing to suboptimal component alignment. We used an imageless navigation device to intraoperatively quantify the magnitude of error between planned and actual resections, hypothesizing final bone cuts will differ from planned alignment. MATERIALS AND METHODS: A retrospective study including 60 consecutive patients undergoing primary TKA using a novel imageless navigation device was conducted. Device measurements of resection parameters were obtained via attachment of optical trackers to femoral and tibial cutting guides prior to resection. Following resection, optical trackers were placed directly on the bone cut surface and measurements were recorded. Cutting guide and bone resection measurements of both femoral and tibial varus/valgus, femoral flexion, tibial slope angles, and both femoral and tibial medial and lateral resection depths were compared using a Student's t-test. RESULTS: Femoral cutting guide position differed from the actual cut by an average 0.6 ± 0.5° (p = 0.85) in the varus/valgus angle and 1.0 ± 1.0° (p = 0.003) in the flexion/extension angle. The difference between planned and actual cut measurements for medial and lateral femoral resection depth was 1.1 ± 1.1 mm (p = 0.32) and 1.2 ± 1.0 mm (p = 0.067), respectively. Planned cut measurements based on tibial guide position differed from the actual cut by an average of 0.9 ± 0.8° (p = 0.63) in the varus/valgus angle and 1.1 ± 1.0° (p = 0.95) in slope angle. Measurement of medial and lateral tibial resection depth differed by an average of 0.1 ± 1.8 mm (p = 0.78) and 0.2 ± 2.1 mm (p = 0.85), respectively. CONCLUSIONS: Significant discrepancies between planned and actual femoral bone resection were demonstrated for flexion/extension angle, likely the result of cutting error. Our data highlights the importance of cut verification postresection to confirm planned resections are achieved, and suggests imageless navigation may be a source of feedback that would allow surgeons to intraoperatively adjust resections to achieve optimal implant alignment.

Diagnosis of Guillain-Barré Syndrome After Total Hip Arthroplasty: A Case Report.

CASE REPORT: A 67-year-old man presented with signs of acute periprosthetic infection after total hip arthroplasty (THA). Surgical debridement, antibiotics, and a head and liner exchange were performed. After showing no improvement, a single-stage revision was conducted. Postoperatively, he developed back pain and lower extremity weakness. Electrodiagnostic studies showed a Guillain-Barré syndrome (GBS) variant. Intravenous immunoglobulin was administered to halt disease progression. After 1 year, he still demonstrated neuromuscular deficits and required a cane for ambulation. CONCLUSION: This case highlights GBS after THA. A high degree of clinical suspicion is essential to prevent misinterpretation as a postsurgical complication. LEVEL OF EVIDENCE: V, case report.

Safety and Efficacy of Same-Day Hip Resurfacing.

Same-day discharge (SDD) surgery in total hip arthroplasty (THA) has been shown to have similar outcomes to non-SDD THA in select patient populations. Hip resurfacing arthroplasty (HRA) is an alternative to THA for young, active patients, making them ideal candidates for SDD. This study compared the safety and efficacy of non-SDD HRA and SDD HRA for specific postoperative outcomes. An electronic data warehouse query was performed for procedures labeled "hip resurfacing." Data collected included demographics, surgical factors, and quality metrics. Statistical analyses were evaluated using a graphing and statistics software program. Categorical variables were analyzed with chi-square tests and continuous variables with Student's t tests, with P<.05 deemed significant. Sixty-three of 274 total HRAs were enrolled in this SDD HRA protocol. No significant difference was observed between SDD HRA and non-SDD HRA baseline characteristics. On postoperative day 0, 98.41% of SDD HRA recipients were discharged successfully. The SDD HRA recipients had shorter stays, with 1.59% requiring a hospital stay of 2 days or more compared with 56.87% of non-SDD HRA recipients (P<.0001). The non-SDD HRA recipients were found to have shorter surgical times than SDD HRA recipients (104.74 vs 125.51 minutes, P=.01). Rates of infection, periprosthetic fractures, emergency department visits, and hospital readmissions were equivalent (P=.99). Same-day discharge HRA is a safe and effective procedure with similar outcomes to non-SDD HRA regarding infections, fractures, emergency department visits, and readmissions. The major benefit of SDD is a shorter hospital stay that may lead to decreased cost while preserving and enhancing quality of care and patient satisfaction. [Orthopedics. 2020;43(6):e595-e600.].

No difference in failure rates or clinical outcomes between non-stemmed constrained condylar prostheses and posterior-stabilized prostheses for primary total knee arthroplasty.

PURPOSE: There has been an increase in the use of unlinked constrained condylar knee (CCK) prostheses in primary total knee arthroplasty (TKA) for cases with significant deformities that cannot be adequately balanced in flexion and extension. However, the literature on its outcomes is limited. The goal of this study is to evaluate whether there are any clinic or radiographic outcome differences for a primary, non-stemmed, unlinked constrained TKA as compared to a control group of posterior-stabilized (PS) TKA using the same implant design. METHODS: Clinical and radiographic outcome measures for 404 cemented, non-stemmed, primary TKAs performed by two surgeons at the same institution were retrospectively reviewed. All patients underwent primary, non-stemmed components; 241 used CCK inserts and 163 used PS inserts. Preoperative deformity, knee society scores (KSS), range-of-motion (ROM), radiographic data and revision rates were compared between the CCK and PS groups. RESULTS: Both groups had comparable demographics and preoperative ROM and KSS. At similar mean follow-up times (6.1 ± 1.0 years for the CCK group and 6.3 ± 1.2 years for the PS group), no significant difference was found in ROM, KSS or radiographic outcomes. Revision rates were higher for the CCK group (2%) as compared to the HF-PS (0.6%) group (n.s). CONCLUSIONS: The particular design of cemented, primary, non-stemmed, unlinked CCK-TKA examined in this study provided similar clinical and radiographic outcomes to that of PS-TKA at midterm follow-up. LEVEL OF EVIDENCE: III.

The learning curve following adoption of a novel short-stem prosthesis in total hip arthroplasty: implications on short-term patient outcomes.

BACKGROUND: Short-stem (SS) hip prostheses for total hip arthroplasty (THA) have gained popularity as surgeons strive to reproduce physiological stress distributions at the proximal femur. Additionally, as THA indications continue to target younger populations, preservation of femoral bone stock for potential revision surgeries is particularly appealing. However, little is known regarding the short-term complications of each variety of short stem during the learning curve period. The purpose of this study is to evaluate the short-term complications among the THA recipients with the use of a novel SS hip prosthesis. METHODS: A retrospective chart review was performed of all patients undergoing primary THA utilizing an Echo Bi-Metric Microplasty hip stem. Patient demographics, surgical factors, complications and quality outcomes were collected utilizing our institution's data warehouse and verified by chart review. RESULTS: In total, 182 SSs were implanted in 168 patients undergoing primary THA. Of these, 5 (2.9%) patients sustained a periprosthetic fracture. Two fractures occurred during the index hospital admission, and 3 occurred in the post-discharge period. Subset analysis demonstrated that 4 (80%) fractures had occurred during the initial learning curve period, within the first 30 surgical cases with a SS. CONCLUSION: Short-stem hip prostheses are a safe alternative for THA. The results of the present study demonstrate a fracture incidence of 2.9% among patients. However, surgeons should remain cautious when utilizing new implant system and expect a learning curve. In this study, 80% of periprosthetic fractures following SS THA occurred within the first 30 cases for experienced arthroplasty-trained surgeons.

Ultra-High-Molecular-Weight Polyethylene (UHMWPE) in Total Joint Arthroplasty.

Total joint arthroplasty of the hip and knee are successful orthopedic procedures that reduce pain and improve mobility in patients. As the implanted materials used in these procedures have improved, the lifetime of the implants has now reached more than 20 years. Younger patients are undergoing total joint arthroplasty at increasing rates, which has increased the need for improvements in materials for extended implant longevity. In this review, we aim to provide historical perspective on the evolution of ultra-high-molecular-weight polyethylene in total joint arthroplasty. We review this material with respect to its structure, mechanical properties, wear rates, sterilization effects, crosslinking, and other new polymer innovations. Ultra-high-molecular-weight polyethylene (UHMWPE) has been a cornerstone for total joint arthroplasty and with continued design improvements will continue to be vital to this successful orthopedic operation.

Managing Acetabular Defects in Total Hip Arthroplasty.

With the aging population and rising incidence of primary total joint arthroplasty has come the increasing incidence of revision total hip arthroplasties. One challenge in revision total hip arthroplasty is dealing with acetabular defects. The orthopaedic surgeon who chooses to take on these challenges requires a proper method for the evaluation of these defects as well as an evidence-based treatment algorithm. Initial assessment requires appropriate use and interpretation of imaging modalities such as x-rays and computed tomography. Preoperative planning presupposes knowledge of available approaches and implant options, such as porous coated jumbo cups, modular augments, and cup-cage constructs. Surgical execution necessitates experience in the indications for each type of implant for various types of defects. This review will aid in the understanding of each step of the diagnosis and treatment of acetabular defects in revision total hip arthroplasty.

Does a non-stemmed constrained condylar prosthesis predispose to early failure of primary total knee arthroplasty?

PURPOSE: The use of unlinked constrained condylar components (CCK) has been extended to primary total knee arthroplasty (TKA); however, there is limited literature on its outcomes. The purpose of this retrospective cohort study was to assess clinical outcomes of one particular design of primary, non-stemmed, unlinked constrained TKA and to compare them with a control group of PS-TKA utilizing the same implant design. METHODS: The clinical and radiographic outcomes of 486-cemented, non-stemmed, primary TKA's performed by two surgeons at one institution using similar surgical algorithm, technique and prosthetic design were retrospectively reviewed. Primary TKA components were used in all knees; the only difference between groups was the type of polyethylene inserts used (CCK vs PS). Pre-operative deformity, knee society scores (KSS), range-of-motion (ROM), radiographic data and revision rates were compared. RESULTS: Both groups had comparable demographics, pre-operative coronal plane alignment, ROM and KSS. At a mean follow-up of 3.5 years, no difference was found in ROM, KSS, radiographic outcomes and revision rates. CONCLUSIONS: Cemented, primary, non-stemmed CCK-TKA offered comparable clinico-radiographic results to PS-TKA at short-term follow-up. Use of a semi-constrained insert without additional stems did not predispose to failure due to aseptic loosening with this implant design. Moreover, the rate of revision due to instability was lowered. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.

Revision of Failed Hip Resurfacing and Large Metal-on-Metal Total Hip Arthroplasty Using Dual-Mobility Components.

Revision of metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing is associated with high complication rates. The authors propose dual-mobility components as a surgical option and present short- to mid-term results of MoM hips revised with dual-mobility components. Eighteen consecutive hips that underwent revision of MoM THA or hip resurfacing using dual-mobility components were identified. At final follow-up (mean, 17.5 months), the visual analog scale, modified Harris Hip Score, and SF-12 scores had all improved (P<.05, P<.01, and P<.05, respectively). There were no dislocations or other complications. Revision of failed MoM THA or hip resurfacing using a dual-mobility device is an effective strategy.

Iliac wing insufficiency fractures as unusual postoperative complication following total hip arthroplasty - a case report.

Insufficiency fractures present a significant problem in patients with osteoporosis. We report a case of bilateral iliac wing insufficiency fracture following low energy injury in an 87-year-old osteoporotic woman occurring 2 weeks after primary total hip arthroplasty. There are only a few reports of insufficiency fractures involving the ilium in the literature, and diagnosis has proven challenging, as radiographs are often negative at symptom onset. Magnetic resonance or radionuclide imaging is generally necessary for definitive diagnosis. This case highlights the importance of careful perioperative management of patients with osteoporosis.