Association Between Pseudotumor Formation and Patient Factors in Metal-on-Metal Total Hip Arthroplasty Population.

BACKGROUND: Pseudotumor formation from metal-on-metal (MoM) hip implants is associated with implant revision. The relationship between pseudotumor type and patient outcomes is unknown. METHODS: We retrospectively reviewed patients with a MoM total hip arthroplasty and metal artifact reduction sequence magnetic resonance imaging. Pseudotumors were graded using a validated classification system by a fellowship-trained radiologist. Patient demographics, metal ion levels, and implant survival were analyzed. RESULTS: Pseudotumors were present in 49 hips (53%). Thirty-two (65%) pseudotumors were cystic thin walled, 8 (16%) were cystic thick walled, and 9 (18%) were solid masses. Patients with pseudotumors had high offset stems (P = .030) but not higher metal ion levels. Patients with thick-walled cystic or solid masses were more likely to be symptomatic (P = .025) and were at increased risk for revision (P = .004) compared to patients with cystic lesions. CONCLUSION: Pseudotumor formation is present in 53% of patients with a MoM total hip arthroplasty, of which 40% were asymptomatic. Patients with thick-walled cystic and solid lesions were more likely to be symptomatic and undergo revision.

Comparison of Postoperative Complications Following Metal-on-Metal Total Hip Arthroplasty With Other Hip Bearings in Medicare Population.

BACKGROUND: The use of metal-on-metal (MoM) hip bearings has declined in the recent years due to strong evidence of their high complication rates and early failure. Hip implants with highly cross-linked polyethylene liners and ceramic bearings have become the modern implants of choice. We sought to determine if MoM implants are associated with higher complication and revision rates when compared to other hip bearings in the Medicare population. METHODS: We retrospectively reviewed a Medicare database (2005-2011) for patients who underwent a primary total hip arthroplasty with a MoM, metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), or ceramic-on-ceramic (CoC) implant (minimum 2 years of follow-up). Patient comorbidities and medical/surgical complication rates were analyzed at various time points postoperatively. RESULTS: We identified 288,118 patients, including 81,520 patients with a MoM implant, 162,881 with MoP, 33,819 with CoP, and 9898 with CoC implant. Surgical complication rates were higher for MoM implants including infection, osteolysis/polywear, mechanical complications, and need for hip irrigation and debridement. Overall revision rates were significantly higher for MoM implants (5.28%) compared to MoP (4.28%, odds ratio [OR] 1.26, P < .001) and CoP (3.52%, OR 1.55, P < .001) but only by one to two percent. MoM revision rates were similar to CoC implants (4.94%, OR 1.00, P = .096). CONCLUSIONS: MoM implants were associated with higher revision rates (5.28%) compared to MoP (4.28%) and CoP (3.52%) implants in the Medicare population. Both complication and revision rates were comparable to CoC implants.

Bearing Surfaces for Total Hip Arthroplasty.

Metal-on-highly cross-linked polyethylene is considered the preferred bearing surface for conventional total hip arthroplasty because of its safety profile and excellent results in the first 10 to 15 years of use. However, with younger patient age, activity expectations increase, and the life expectancy of patients with total hip arthroplasty also has increased, so interest remains in other bearing couples. These other options include the use of various ceramic composites for the femoral head on highly cross-linked polyethylene, the so-called second-generation antioxidant polyethylenes, and ceramic acetabular liners. Several of these bearing couples have shown excellent wear rates in vitro, and short-term clinical studies have demonstrated favorable wear and safety results. It is uncertain whether any of these bearing couples should be adopted at present. Understanding the unique properties and possible complications of these bearing couples is critical for appropriate implant selection.

What Factors Drive Inpatient Satisfaction After Knee Arthroplasty?

BACKGROUND: The Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey, developed by the Centers for Medicare & Medicaid Services, is directly tied to hospital reimbursement. The purpose of this study is to analyze survey responses from patients who underwent primary knee arthroplasty in order to identify factors that drive patient dissatisfaction in the inpatient setting. METHODS: HCAHPS responses received from patients undergoing elective total and unicompartmental knee arthroplasty at our institution between January 1, 2013 and January 1, 2016 were obtained and expressed as a percentage of overall satisfaction. Satisfaction scores were correlated to patient demographics. RESULTS: Overall, responses from 580 patients were obtained (554 total knee arthroplasties, 26 unicompartmental knee arthroplasties). There was a statistically significant difference in overall satisfaction when comparing sex (P = .034), race (P = .030), and socioeconomic status (P = .001). Men reported a higher average satisfaction score than women (77.8% vs 74.2%). Patients in the 1st quartile of socioeconomic status reported a higher average satisfaction than those in the 4th quartile (81.3% vs 71.3%). African American patients reported a higher satisfaction than Caucasian and other races (81.6% vs 75.3% vs 66.3%, respectively). There was an inverse relationship between increased length of stay and reported satisfaction (r = -0.113, P = .006). CONCLUSION: Our data indicate that patients who are likely to report higher levels of inpatient satisfaction after knee arthroplasty are male, African American, of lower socioeconomic status, and with shorter length of stay. To our knowledge, this is the first reported analysis of the HCAHPS survey in relation to total joint arthroplasty.

C5 palsy after cervical laminectomy and fusion: does width of laminectomy matter?

BACKGROUND CONTEXT: A common complication of cervical laminectomy and fusion with instrumentation (CLFI) is development of postoperative C5 nerve palsy. A proposed etiology is excess nerve tension from posterior drift of the spinal cord after decompression. We hypothesize that laminectomy width will be significantly increased in patients with C5 palsy and will correlate with palsy severity. PURPOSE: The purposes of this study were to evaluate laminectomy width as a risk factor for C5 palsy and to assess correlation with palsy severity. STUDY DESIGN/SETTING: This is a retrospective, single-institution clinical study. PATIENT SAMPLE: Patient population included all patients with cervical spondylotic myelopathy who underwent CLFI between 2007 and 2014 by a single surgeon. Patients who underwent CLFI for trauma, infection, or tumor or had previous or circumferential cervical surgery were excluded. All patients with a new C5 palsy received a postoperative magnetic resonance imaging. An additional computed tomography (CT) scan was ordered to assess hardware. All control patients received a CT scan at 6 months postoperatively to evaluate fusion. OUTCOME MEASURES: The association between width of laminectomy and development of postopeative C5 palsy was measured. METHODS: Patient comorbidities including obesity, smoking history, and diabetes were recorded in addition to preopertaive and postoperative deltoid and biceps motor strength. Sagittal alignment was measured with C2-C7 Cobb angle preopertaive and postoperative radiographs. The width of laminectomy was measured in a blinded fashion on the postoperative CT scan by two observers. RESULTS: Seventeen patients with C5 nerve palsy and 12 controls were identified. There were no baseline differences in age, sex, diabetes, smoking history, number of surgical levels, or sagittal alignment. Body mass index was significantly higher in the control cohort. There was no significant increase in the C3-C7 laminectomy width in patients with postoperative C5 palsy. The width of laminectomy measurments were highly similar between the two observers. There was no correlation between laminectomy width and palsy severity. CONCLUSIONS: This is the largest series of C5 palsies after laminectomy documented with CT imaging. Laminectomy width was not associated with an increased risk of postoperative C5 palsy at any level. Reduction in laminectomy width may not reduce rate of postoperative nerve palsy.

The role of iatrogenic foraminal stenosis from lordotic correction in the development of C5 palsy after posterior laminectomy and fusion.

BACKGROUND: Post-operative C5 nerve root palsy is a known complication following cervical spine surgery. Although several theories have been proposed, there remains no consensus as to the etiology of the palsies. Multiple pre-operative radiographic measures have been assessed for utility in predicting palsy. The purpose of this study is to evaluate published radiographic parameters as well as specifically evaluate the effect of cervical lordosis in the development of C5 palsy to establish thresholds that reliably predict the incidence. METHODS: This study is a retrospective review of 54 consecutive multilevel cervical laminectomy and fusion surgeries performed by a single spine surgeon between June 2007 and February 2014. Pre-operative MRI and pre- and post-operative plain films were assessed to measure anteroposterior diameter (APD) of the spinal cord, cervical laminar angles, anteroposterior foraminal diameters (FD), cervical curvature index (Ishihara), cervical spine angle (C2-7), and C4-5 angle. Univariate analysis through independent t tests was used to compare differences between groups. Stepwise logistic regression was performed to identify pre-operative variables associated with C5 palsy. Receiver operating characteristic curves were created for significant variables to assess predictive accuracy through determining the area under the curve. RESULTS: There were 13 (24%) palsies in the 54 patients in the study. All palsies completely resolved within 6 months. Among pre-operative measures, FD and APD were significantly different between the palsy and non-palsy groups. The average post-operative C4-5 angle was significantly different between the groups, though the cervical spine angle and curvature index, as well as the change in these measures from pre-operative measurements, did not differ significantly between groups. CONCLUSIONS: Post-operative palsy is likely a result of iatrogenic nerve root compression from a decreased in cross-sectional area of the neuroforamen in a patient with pre-operative narrowing of the foramen. However, spinal cord drift back may also play a role from the combined effect of posterior decompression from laminectomy and relative slack afforded by increased lordosis. Accordingly, increased post-operative lordosis would increase the likelihood of effect from both of these mechanisms. We recommended limited conservative lordotic correction in patients with pre-operative foraminal narrowing.