Risk Factors for Early Dislocation Following Primary Elective Total Hip Arthroplasty

Background

Dislocation following total hip arthroplasty (THA) continues to be one of the most common reasons for revision THA. The purpose of this study is to measure the current rate of dislocation following THA in the United States. A secondary goal is to identify patients at highest risk of instability after THA.

Impact of the economic downturn on adult reconstruction surgery: a survey of the American Association of Hip and Knee Surgeons

To evaluate the effects of the economic downturn on adult reconstruction surgery in the United States, a survey of the American Association of Hip and Knee Surgeons (AAHKS) membership was conducted. The survey evaluated surgical and patient volume, practice type, hospital relationship, total joint arthroplasty cost control, employee staffing, potential impact of Medicare reimbursement decreases, attitudes toward health care reform options and retirement planning. A surgical volume decrease was reported by 30.4%. An outpatient visit decrease was reported by 29.3%. A mean loss of 29.9% of retirement savings was reported. The planned retirement age increased to 65.3 years from 64.05 years. If Medicare surgeon reimbursement were to decrease up to 20%, 49% to 57% of AAHKS surgeons would be unable to provide care for Medicare patients, resulting in an unmet need of 92,650 to 160,818 total joint arthroplasty procedures among AAHKS surgeons alone. Decreases in funding for surgeons and inadequate support for subspecialty training will likely impact access and quality for Americans seeking adult reconstruction surgery.     

Long-Term Results of a Contemporary Metal-on-Metal Total Hip Arthroplasty : A 10-Year Follow-Up Study

The goal of the study was to evaluate the long-term results of a metal-on-metal articulation. We evaluated the results and histologic findings in patients who had undergone revision. One hundred total hip arthroplasties with a Lubrimet metal-on-metal articulation (Smith and Nephew, Rotkreuz, Switzerland) were implanted in 99 consecutive unselected patients in 1995 and 1996, and the results were prospectively analyzed up to a mean of 126 months postoperatively. Periprosthetic tissues of all 6 hips that had undergone revision because of aseptic loosening, mechanical failure, or periprosthetic fracture showed metallosis and extensive lymphocytic and plasma cell infiltration around the metal debris. With removal of the component because of aseptic loosening as the end point, survivorship was 98% for the stem and 96% for the cup.     

The effect of entrapped bone particles on the surface morphology and wear of polyethylene

Clinically retrieved highly cross-linked ultrahigh molecular weight polyethylene (HXPE) acetabular liners have demonstrated scratching, whereas conventional ultrahigh-molecular-weight polyethylene (UHMWPE) implants show a smoother surface early after implantation. In the present study, the potential of bone particles and soft tissues, rather than cement, to scratch the articular surface of HXPE and UHMWPE (gamma radiated) acetabular components was evaluated; multiple bone particles located at the articular surface for 3600 simulated walking cycles replicated the scratches observed on retrieved implants. By remelting, these scratches were confirmed to be due to plastic deformation of the polyethylene, not wear. Furthermore, it was shown using wear testing that these scratches did not affect the subsequent wear rate of HXPE or conventional UHMWPE. Wear rates of scratched conventional and cross-linked polyethylene were not significantly different from unscratched conventional and cross-linked polyethylene, respectively.     

Predictors of activity limitation and dependence on walking aids after primary total hip arthroplasty

OBJECTIVES: To study function outcomes and their predictors after primary total hip arthroplasty (THA). DESIGN: Prospective cohort study. SETTING: Mayo Clinic. PARTICIPANTS: All patients who underwent primary THA at the Mayo Clinic between 1993 and 2005 and were alive at the time of follow‐up. MEASUREMENTS: Whether sex, age, body mass index (BMI), comorbidity, anxiety, and depression predict moderate to severe activity limitation (limitation in ≥3 activities) and complete dependence on waling aids 2 and 5 years after primary THA was examined. Multivariable logistic regression adjusted for operative diagnosis, American Society of Anesthesiologists score, implant type, and distance from medical center. RESULTS: At 2 years, 30.3% of participants reported moderate to severe activity limitation; at 5 years, 35% of participants reported moderate to severe activity limitation. Significant predictors of moderate to severe activity limitations at 2‐year follow‐up were female sex (odds ratio (OR)=1.2, 95% confidence interval (CI)=1.1–1.4), aged 71 to 80 (OR=2.0, 95% CI=1.6–2.5), aged 80 and older (OR=4.5, 95% CI=3.4–6.0), depression (OR=2.1, 95% CI=1.6–2.7), and BMI greater than 30.0. At 5‐year follow‐up, significant predictors were aged 71 to 80 (OR=1.7, 95% CI=1.3–2.2), older than 80 (OR=4.3, 95% CI=2.8–6.6), depression (OR=2.3, 95% CI=1.6–3.4), and BMI greater than 30.0.Significant predictors of complete dependence on walking aids at 2 years were female sex (OR=2.0, 95% CI=1.4–2.7), aged 71 to 80 (OR=2.4, 95% CI=1.4–4.2), older than 80 (OR=11.4, 95% CI=6.0–21.9), higher Deyo‐Charlson score (OR=1.5, 95% CI=(1.1–1.2) for 5‐point increase, depression (OR=2.0, 95% CI=1.2–3.4), and BMI greater than 35.0. Each of these factors also significantly predicted complete dependence on walking at 5‐year follow‐up, with similar odds ratios, except that BMI of 30.0 to 34.9 was not significantly associated. CONCLUSION: Higher BMI, depression, older age, and female sex predict activity limitation and complete dependence on walking aids 2 and 5 years after primary THA.     

Total hip arthroplasty following failed fixation of proximal hip fractures

Background:

Most proximal femoral fractures are successfully treated with internal fixation but a failed surgery can be very distressing for the patient due to pain and disability. For the treating surgeon it can be a challenge to perform salvage operations. The purpose of this study was to evaluate the short-term functional outcome and complications of total hip arthroplasty (THA) following failed fixation of proximal hip fracture.

Materials and Methods:

In a retrospective study, 21 hips in 20 patients (13 females and seven males) with complications of operated hip fractures as indicated by either established nonunion or fracture collapse with hardware failure were analysed. Mean age of the patients was 62 years (range 38 years to 85 years). Nine patients were treated for femoral neck fracture, 10 for intertrochanteric (I/T) fracture and two for subtrochanteric (S/T) fracture of the hip. Uncemented THA was done in 11 cases, cemented THA in eight hip joints and hybrid THA in two patients.

Results:

The average duration of follow-up was four years (2-13 years). The mean duration of surgery was 125 min and blood loss was 1300 ml. There were three dislocations postoperatively. Two were managed conservatively and one was operated. There was one superficial infection and one deep infection. Only one patient required a walker while four required walking stick for ambulation. The mean Harris Hip score increased from 32 preoperatively to 79 postoperatively at one year interval.

Conclusion:

Total hip arthroplasty is an effective salvage procedure after failed osteosynthesis of hip fractures. Most patients have good pain relief and functional improvements inspite of technical difficulties and high complication rates than primary arthroplasty.     

The influence of acetabular component position on wear in total hip arthroplasty

Our experience has implicated cup inclination as an important factor in wear, whereas others have suggested that the hip center of rotation (COR) must be closely reestablished to reduce wear. We conducted a retrospective study to determine the relative importance of these 2 factors. One hundred thirty-nine total hip arthroplasties were studied after a mean follow-up of 9.2 years (range, 6-3 years). Forty-nine of 139 operated hips had a contralateral normal hip, which allowed the most accurate measurement of the influence of change in the COR. Wear was related to the inclination of the cup but not to a change in the COR. Secondarily, wear was less with a ceramic-polyethylene polyarticular surface than with metal-polyethylene. The importance of this data is related to cup implantation techniques. The hip COR can be moved superiorly and/or medially to permit cup inclination below 45 degrees with correct cup coverage.     

Does the anterior approach for total hip arthroplasty better restore stair climbing gait mechanics?

While total hip arthroplasty (THA) provides pain relief and restores mobility, gait anomalies persist even years after surgery. A muscle sparing surgical approach could result in better postoperative gait mechanics. Our purpose was to compare both the anterior muscle sparing approach and the direct lateral approach (LAT) to a matched control group by using three‐dimensional motion analysis while performing stair ascent and descent tasks. Lower‐limb kinematics and kinetics were recorded for 20 patients that had an anterior approach (ANT), 20 that had a LAT, and 20 age‐ and weight‐matched control participants. Patients were assessed on average 10 months after surgery. Compared to the control group, during stair ascent, the anterior group had reduced peak hip extension, peak hip flexion moment, and peak hip power. The lateral group had reduced peak hip abduction, hip frontal plane range of motion, and peak hip internal rotation. In stair descent, the anterior group had reduced peak hip flexion, peak hip abduction moment and internal rotation, as well as peak hip power. The lateral group had reduced peak hip flexion, peak knee extension moment, and peak hip power. Therefore, gait anomalies persist after THA for both approaches, which could be due to other factors such as preoperative gait adaptations. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1412–1417, 2011