Mortality After Revision Total Hip Arthroplasty.

BACKGROUND: In counseling patients about the complications of revision total hip arthroplasty (revTHA), it is imperative that mortality be considered. The actual mortality rate by indication of revision is ill-defined. The purpose of this study is to determine the mortality rate after revTHA. METHODS: An institutional database identified 596 patients who had undergone revTHA between 2012 and 2018. Medical records, national, state, and local death indexes were queried for mortality status and indication for revTHA. For survivors, the last clinical visit date was used for censoring in the mortality analysis. Mortality rates were calculated for all clinical patients and then by specific indication for revision. RESULTS: The overall 2-year mortality rate following revTHA was 19.5 deaths per 1000 or 1 in 51 patients. Patients presenting with a periprosthetic fracture had a significantly higher 2-year mortality rate of 74.5 deaths per 1000 or 1 in 13 patients (P < .001), while an indication of dislocation or instability had a slightly higher 2-year mortality rate of 50.3 per 1000 (1 in 20) but this difference was not significant (P = .531). Other indications such as mechanical loosening or infection did not have a significantly different mortality rate. CONCLUSION: The overall 2-year mortality rate following revTHA was 19.5 deaths per 1000 which was largely attributed to patients with a periprosthetic fracture (74.5 per 1000) with other indications not significantly impacting mortality. Mortality rates and specific rates by indication for revision should be considered when counseling patients prior to revTHA.

Long-term performance of oxidized zirconium on conventional and highly cross-linked polyethylene in total hip arthroplasty.

INTRODUCTION: Polyethylene wear and subsequent osteolysis remain obstacles to the long-term survivorship of total hip arthroplasty (THA). Highly cross-linked polyethylene (XLPE) with radical quenching represents a massive leap forward with dramatically improved wear rates compared to ultra-high molecular weight polyethylene (UHMWPE). In this study we evaluate the wear of UHMWPE and XLPE coupled with oxidized zirconium (OxZr) femoral heads. METHODS: A longitudinal, retrospective analysis was performed identifying consecutive patients who received a 28-mm OxZr-on-polyethylene primary THA from 2003 to 2004 by a single, high-volume arthroplasty surgeon. Patients were divided into two groups: those that received (1) UHMWPE liner and (2) a highly XLPE liner. Patients were included if clinical follow-up was complete to 2014 or later. Radiographic analysis was performed by two blinded observers. Measures included cup position, annual linear wear rate, and presence of osteolysis. Pairwise comparisons, correlations, and inter-rater reliability were calculated. RESULTS: Eighty patients were in the UHMWPE group with an average follow-up of 10 ± 1.23 years and 88 patients in the XLPE group with an average of 10 ± 1.03-year follow-up. Average age (68) was similar between groups (p = 0.288). Observer reliability was excellent for cup abduction (ICC = 0.940), anteversion (ICC = 0.942), and detection of osteolysis (ICC = 0.811). Annual linear wear rates were significantly higher (p = 1 × 10-19) with UHMWPE (0.21 ± 0.12 mm/year) compared to XLPE (0.05 ± 0.03 mm/year). Linear wear rate was significantly correlated to decreasing acetabular abduction (p = 0.035). Osteolysis was noted only in the UHMWPE group, with 17 patients (21.2%) exhibiting acetabular osteolysis and 37 (46.3%) patients exhibiting femoral osteolysis. CONCLUSIONS: OxZr coupled with XLPE showed minimal wear and no osteolysis at 10-year follow up. The yearly linear penetration rate is similar to that seen in other studies of XLPE THA. A careful longitudinal follow-up will be required to determine if advanced bearings such as OxZr or ceramic can show improved performance in the second decade of implantation.

Timing of Pavlik Harness Initiation: Can We Wait?

BACKGROUND: Developmental dysplasia of the hip is effectively treated with a Pavlik harness (PH) within the first 6 months of life. Over 80% of unstable hips in the newborn period will naturally stabilize by 2 months of age. If there is no difference in the effectiveness of initiating PH treatment at 1 week compared with 4 weeks of age, waiting may allow the hips to naturally stabilize and avoid treatment. The purpose of this study is to evaluate whether the timing of PH implementation influences its effectiveness in the treatment of developmental dysplasia of the hip. METHODS: A retrospective review was conducted between 2004 and 2010. Patients were included if PH therapy was prescribed for hip instability or dislocation at or before 6 months of age. PH failure was defined as requiring any operative procedure for definitive management. Groups were divided based on the age at which the PH was initiated-group1=<30 days, group 2=30 to 60 days, group 3=>60 days. RESULTS: A total of 176 children were included with 38 (21.6%) failing PH treatment. The mean age at PH initiation was 1.3 months (SD=1.3) in the successfully treated children and 1.4 months (SD=1.2) in the failures (P=0.77). There was no difference in the failure rates by age with group 1=19.1% (18/94), group 2=22.5% (9/40), and group 3=26.2% (11/42) (P=0.87). There was no statistical difference with respect to sex or breech positioning in the success or failure groups; however, there was a higher percentage of bilateral involvement in the failure group (P=0.04). CONCLUSIONS: Patients who had PH initiation before 30 days of age were no more or less likely to fail than when PH was initiated after 30 days of age. Parents can be counseled that waiting until after 30 days of age is appropriate before PH implementation. By avoiding swaddling during this period, the hips may stabilize without treatment and allow for more parental-infant bonding before implementation of PH. LEVEL OF EVIDENCE: Level III-therapeutic, case control study.

Increased Orthopedic Specialization Lowers Costs and Improves Outcomes in Total Joint Arthroplasty.

BACKGROUND: Total joint arthroplasty (TJA) volumes have risen in the past decade, resulting in increased national spending. Prior studies indicate that TJA performed at higher-volume hospitals result in better patient outcomes at lower costs. The purpose of this study is to determine whether increased orthopedic specialization has similar effects. METHODS: Centers for Medicare and Medicaid Services Inpatient Charge Data queries identified 2677 hospitals that performed TJA in 2015. Hospitals were assigned an orthopedic specialization ratio (OSR), defined as the ratio of musculoskeletal discharges to total discharges. Average covered charges (ACC), average total payments, and average Medicare payments (AMP) of TJA were extracted. TJA-specific, risk-adjusted complication and readmission scores were obtained from the Centers for Medicare and Medicaid Services Hospital Compare database. Comparisons between orthopedic specialty hospitals and nonspecialty hospitals performing TJA were made with Student t-tests. Regression models analyzed the relationship between OSR, volume and cost, payments, readmission rate score, and complication rate score. RESULTS: Orthopedic specialty hospitals had lower ACC, average total payments, AMP, readmission, and complication scores than nonspecialty hospitals (all P < .001). Regression models showed that as the OSR increased from 0 to 1.0, ACC decreased by $19,242.83 and AMP decreased by $2310.75 (P < .001). Readmission score decreased by 0.349 and complication score decreased by 0.346 (P < .001) when controlling for volume as the OSR increased from 0 to 1. CONCLUSION: Hospitals with increased OSR appear to perform TJA for Medicare patients at a lower cost with lower complication and readmission risk. It may be beneficial to consider the OSR when determining the ideal settings for TJA.

Socio-demographic factors impact time to discharge following total knee arthroplasty.

AIM: To determine social, logistical and demographic factors that influence time to discharge in a short stay pathway (SSP) by following total knee arthroplasty (TKA). METHODS: The study included primary TKA's performed in a high-volume arthroplasty center from January 2016 through December 2016. Potential variables associated with increased hospital length of stay (LOS) were obtained from patient medical records. These included age, gender, race, zip code, body mass index (BMI), number of pre-operative medications used, number of narcotic medications used, number of patient reported allergies (PRA), simultaneous bilateral surgery, tobacco use, marital status, living arrangements, distance traveled for surgery, employment history, surgical day of the week, procedure end time and whether the surgery was performed during a major holiday week. Multivariate step-wise regression determined the impact of social, logistical and demographic factors on LOS. RESULTS: Eight hundred and six consecutive primary SSP TKA's were included in this study. Patients were discharged at a median of 49 h (post-operative day two). The following factors increased LOS: Simultaneous bilateral TKA [46.1 h longer (P < 0.001)], female gender [4.3 h longer (P = 0.012)], age [3.5 h longer per ten-year increase in age (P < 0.001)], patient-reported allergies [1.1 h longer per allergy reported (P = 0.005)], later procedure end-times [0.8 h longer per hour increase in end-time (P = 0.004)] and Black or African American patients [6.1 h longer (P = 0.047)]. Decreased LOS was found in married patients [4.8 h shorter (P = 0.011)] and TKA's performed during holiday weeks [9.4 h shorter (P = 0.011)]. Non-significant factors included: BMI, median income, patient's living arrangement, smoking status, number of medications taken, use of pre-operative pain medications, distance traveled to hospital, and the day of surgery. CONCLUSION: The cost of TKA is dependent upon LOS, which is affected by multiple factors. The clinical care team should acknowledge socio-demographic factors to optimize LOS.

Clinical Outcomes Following the Use of Constrained Condylar Knees in Primary Total Knee Arthroplasty.

BACKGROUND: Certain clinical or adverse intraoperative situations require the use of increased constraint in primary total knee arthroplasty (TKA). These include significant angular deformities causing incompetent collateral ligaments, or inadvertent intraoperative injury to collateral structures as well as the inability to achieve a balanced flexion and extension gap. Clinical success has been described with the use of constrained condylar knee arthroplasty in the primary setting in these situations. Traditionally, increasing constraint has been in conjunction with intramedullary stems, referred to as stemmed constrained condylar knees (SCCK); however, some devices provide an intermediary option by increasing constraint without the use of stems, herein referred to as nonstemmed constrained condylar knees (NSCCK). The aim of this study was to compare the clinical outcomes of both these devices in primary TKA in terms of revision rates and change in outcome measures over the follow-up period. METHODS: Between 2007 and 2012, 85 SCCKs and 354 NSCCKs were identified in our institutional registry database performed in the primary TKA setting with minimum 2-year clinical outcome measure follow-up. Baseline demographic information, as well as Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Lower Extremity Activity Scale (LEAS) were collected preoperatively at 2-year follow-up. Revision data were also collected. RESULTS: Both groups showed substantial improvement in WOMAC scores (pain, stiffness, and function), and LEAS at 2 years postoperatively compared with baseline, although the changes in scores were not statistically significant. One of 85 SCCKs (1.17%) was revised for infection, whereas 9 of 354 NSCCKs (2.54%) were revised (6 for mechanical complications, eg, loosening, 2 for periprosthetic fracture, and 1 for infection). CONCLUSION: Both cohorts demonstrated improvement in clinical outcome measures at 2-year follow-up. None of the SCCKs performed in the primary setting were revised for a mechanical complication. Although both groups had overall low revision rates, there was trend toward a higher revision rate with NSCCKs. Many of these were revised for component loosening. In summary, when necessary, constrained options in the primary TKA setting provide excellent clinical outcome at short-term follow-up. However, constrained constructs with stemmed fixation may provide more rigid fixation and be less susceptible to mechanical failure.

Radiographically Silent Loosening of the Acetabular Component in Hip Arthroplasty.

Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total hip arthroplasty (THA). We conducted a study to determine the incidence of loose acetabular components that did not show frank signs of loosening on either plain radiography or computed tomography (CT), or radiographically silent loosening (RSL). In this retrospective study, we evaluated patients who underwent revision THA and were evaluated with plain radiography and CT between 2000 and 2012. Any patient with imaging that showed signs of component movement was excluded. Of the 104 patients who met the study inclusion criteria, 17 (16.3%) met the criteria for RSL of the acetabular shell. Patients with RSL presented at a similar age (P = .961) and with a similar sex profile (P = .185) compared with patients with stable acetabular components and were more likely to present with pain (P = .0487). Acetabular components may be loose even if there is no evidence of component migration on radiographic studies. Surgeons should be aware of the incidence of RSL and the potential of RSL to affect patient care and potential surgical options.

Does Implant Design Influence the Accuracy of Patient Specific Instrumentation in Total Knee Arthroplasty?

PSI software adjusts preoperative planning to accommodate differences in implant design. Such adjustments may influence the accuracy of intraoperative jig placement, bone resection, or component placement. Our purpose was to determine whether implant design influences PSI accuracy. 96 and 123 PSI TKA were performed by a single surgeon using two different implant systems and identical PSI software. Femoral coronal alignment outliers were greater for Implant 1 (23.9% Implant 1 vs. 13.4% Implant 2; P=0.050). Tibial coronal alignment outliers were greater for Implant 2 (10.9% Implant 1 vs. 22.7% Implant 2; P=0.025). There was no difference in overall mechanical axes. Differences in implant design can influence bone resection and component alignment. PSI software rationale must align with surgeons' intraoperative goals.

Femoral component rotation in total knee arthroplasty: an MRI-based evaluation of our options.

Proper femoral component rotation is crucial in successful total knee arthroplasty. Rotation using anatomic landmarks has traditionally referenced the transepicondylar axis (TEA), Whiteside's Line (WSL), or posterior condylar axis (PCA). TEA is thought to best approximate the flexion-axis of the knee, however WSL or PCA are common surrogates in the operating room. This study evaluated 560 knees using MRI-based planning software to assess the relationship of WSL and PCA to the TEA and determine if the relationships were influenced by pre-operative coronal deformity. Results showed the WSL-TEA relationship has more variability than PCA-TEA and that the PCA is more internally rotated in females and valgus knees. Axis options and historical assumptions about axis relationships may need to be reassessed as imaging technology advances.

Aspirin and compression devices versus low-molecular-weight heparin and PCD for VTE prophylaxis in orthopedic oncology patients.

BACKGROUND: Deep venous thrombosis (DVT) and pulmonary embolism (PE) are possible sources of morbidity and mortality in patients with musculoskeletal neoplasms (MSN). OBJECTIVE: To compare the efficacy of aspirin (ASA) and pneumatic compression devices (PCD) to low-molecular-weight heparin (LMWH) and PCD in patients undergoing orthopedic procedures for MSN of the pelvis or lower extremity. METHODS: Of 348 patients who met the study criteria, 195 were treated with ASA/PCD and 153 with LMWH/PCD. There were 18 DVT including 8 in ASA/PCD group and 10 in LMWH/PCD group. There were four PEs, all in the LMWH/PCD group. RESULTS: We found no significant difference in DVT rate between ASA/PCD and LMWH/PCD when used for prophylaxis against thromboembolic complications. Our analysis shows that procedures of the thigh, soft tissue resections, and malignant disease were more often managed with ASA/PCD while joint arthroplasty, procedures of the hip/pelvis, and metastatic disease were more often managed with LMWH/PCD. CONCLUSION: DVT prophylaxis in orthopedic oncology remains a complex topic in which physicians must balance the risks of thromboembolic disease against the risks of post-operative complications.