Lucian C. Warth

Radiographic Structural Abnormalities Associated with Premature, Natural Hip-Joint Failure

BACKGROUND Significant controversy exists regarding the causes of premature, natural hip-joint failure. Identification of these causes may guide future investigations targeting prevention of this disorder. The aims of this study were to: (1) determine and characterize structural abnormalities associated with premature, natural hip-joint failure, and (2) analyze disease progression in the contralateral hips of patients with femoroacetabular impingement deformities. METHODS We analyzed 604 patients (710 hips) from three different medical centers who underwent primary total hip arthroplasty at or before fifty years of age (average age, forty years). Three hundred fourteen patients (52%) were male, and 290 patients (48%) were female. RESULTS The diagnoses associated with premature hip failure varied, but osteoarthritis and osteonecrosis were most common. Radiographic abnormalities associated with developmental hip dysplasia and femoroacetabular impingement were associated with the majority of osteoarthritic hips. Hips with femoroacetabular impingement deformities demonstrated distinct structural anatomy relative to asymptomatic hips, with a high prevalence of bilateral deformities. In a subgroup of seventy patients with femoroacetabular impingement deformities, contralateral radiographic disease progression or the need for total hip arthroplasty was observed in 73% of hips. CONCLUSIONS Osteoarthritis and osteonecrosis are the major causes of premature hip-joint failure in young patients. Femoroacetabular impingement abnormalities are usually bilateral and are commonly associated with progression of the disease to the contralateral hip.

Disparity in Total Joint Arthroplasty Patient Comorbidities, Demographics, and Postoperative Outcomes Based on Insurance Payer Type

Little is known about how patient characteristics differ between insurance types. We reviewed 293 consecutive primary total joint arthroplasty patients with 12-month follow-up and stratified them based on insurance type. As compared with patients with either Medicare or private insurance, Medicaid patients traveled an extra 160 to 170 miles for access to care, both Iowa Care and Medicaid were more than 3 times more likely to be current smokers, and both Iowa Care and Medicaid had lower preoperative and 12-month postoperative 36-Item Short Form Health Survey and WOMAC outcomes scores. Payer type was a significant predictor of 36-Item Short Form Health Survey physical function at final follow-up in a multivariate analysis. Significant disparities exist between patients with different insurance payer types in total joint arthroplasty, and further research into these differences is necessary.

Total Joint Arthroplasty in Patients with Chronic Renal Disease: Is It Worth the Risk?

26-27% of patients with end stage hip and knee arthritis requiring TJR have chronic renal disease. A multi-center, prospective clinical registry was queried for TJAs from 2006 to 2012, and 74,300 cases were analyzed. Renal impairment was quantified using estimated glomerular filtration rate (eGFR) to stratify each patient by stage of CRD (1-5). There was a significantly greater rate of overall complications in patients with moderate to severe CRD (6.1% vs. 7.6%, P<0.001). In those with CRD (Stage 3-5), mortality was twice as high (0.26% vs. 0.48%, P<0.001). Patients with Stage 4 and 5 CRD had a 213% increased risk of any complication (OR 2.13, 95% CI: 1.73-2.62). Surgeons may use these findings to discuss the risk-benefit ratio of elective TJR in patients with CRD.

Improved results using extensively coated THA stems at minimum 5-year followup

The Prodigy® femoral component was extensively coated along its entire length, except for a smooth bullet-shaped distal tip. At a minimum 5 year followup we compared the results of that stem to those of a proximally coated first generation femoral component at comparable followup to address the question of which design performed better. For the extensively coated cohort, 86 patients (100 hips) underwent total hip arthroplasty by a single surgeon. At final followup, no patients were lost to followup and no hips were revised for aseptic loosening. Clinically, 3% of patients reported thigh pain (versus 15% in the proximally coated group). Radiographically, all hips had evidence of bone ingrowth (versus 94% in the PCA group). As expected with an extensively coated device there were fewer radiolucencies around the lower half of the prosthesis as well as less distal femoral lysis compared to the proximally coated stem.Level of Evidence: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Cementless Acetabular Fixation in Patients 50 Years and Younger at 10 to 18 Years of Follow-Up

The purpose of the study was to evaluate the 10- to 18-year follow-up of cementless acetabular fixation in patients 50 years and younger. We retrospectively reviewed a consecutive group of 118 patients (144 hips) in whom primary total hip arthroplasty had been performed by 2 surgeons using a cementless acetabular component. Two (1.4%) cementless acetabular components were revised because of aseptic loosening. Twenty-four hips (16.7%) were revised for any mechanical failure of the acetabular component mostly related to acetabular liner wear and osteolysis. The average linear wear rate was 0.19 mm per year, which was higher than our previous reports with cemented acetabular fixation. The fiber mesh ingrowth surface of the cementless acetabular component in this study was superior to cemented acetabular components in terms of fixation. However, the high rates of wear and osteolysis have led to poor overall acetabular component construct survivorship.

Screw fixation of the syndesmosis alters joint contact characteristics in an axially loaded cadaveric model

BACKGROUND The purpose of this study was to quantify the effects of rigid syndesmotic fixation on functional talar position and cartilage contact mechanics. METHODS Twelve below-knee cadaveric specimens with an intact distal syndesmosis were mechanically loaded in four flexion positions (20° plantar flexion, 10° plantar flexion, neutral, 10° dorsiflexion) with zero, one, or two 3.5-mm syndesmotic screws. Rigid clusters of reflective markers were used to track bony movement and ankle-specific pressure sensors were used to measure talar dome and medial/lateral gutter contact mechanics. RESULTS Screw fixation caused negligible anterior and inferior shifts of the talus within the mortise. Relative to no fixation, mean peak contact pressure decreased by 6%-32% on the talar dome and increased 2.4- to 6.6-fold in the medial and lateral gutters, respectively, depending on ankle position and number of screws. CONCLUSIONS Two-way ANOVA indicated syndesmotic screw fixation significantly increased contact pressure in the medial/lateral gutters and decreased talar dome contact pressure while minimally altering talar position.