Uncemented component retention with polyethylene (PE) liner and femoral head exchange is commonly used to treat periprosthetic osteolysis. The purpose was to determine long-term implant survivorship, risk factors for aseptic failures, clinical outcomes, and complications following PE liner and head exchange.

We identified 116 hips in 110 patients treated with PE liner and head exchange for osteolysis from 1993 to 2004. The mean age was 58, 64 were women, and mean follow-up was 11 years.

Implant survivorship free from all-cause revisions was 91% at 5-years, 81% at 10-years, and 69% at 15-years. Reasons for re-revision included subsequent conventional PE wear and osteolysis in 7 (6%), aseptic acetabular loosening in 5 (4%), and instability in 5 hips (4%). Mean time to revision for aseptic acetabular loosening was 4 years (range 1 – 7 years). Risk factors for aseptic acetabular loosening included acetabular zones of pre-revision osteolysis, percentage of cup involvement, and size of osteolytic defects. Absolute risk of acetabular loosening was 23% for three zones of osteolysis (Relative Risk (RR) 12, p<0.01), 40% if osteolysis involved more than half the cup circumference (RR 14, p<0.01), and 21% for defects greater than 600 mm² (RR 11, p<0.01). Harris hip scores improved from 77 to 87 (p<0.01). The most common complication was dislocation (16%).

These data quantify risk of subsequent component loosening when well fixed, uncemented implants are retained during operations for osteolysis, and may inform operative decisions regarding shell retention versus revision.

Introduction

Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of THA, as well as surgical approach, on gait kinetics and kinematics.

Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of surgical approach on gait kinetics and kinematics. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis.

Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardised implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance.

All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group.

Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question.

Introduction

Total hip arthroplasty (THA) is a commonly performed surgical procedure for the treatment of hip arthritis. Approximately 50,000 THAs are performed annually in Canada. The costs incurred to the healthcare system are tremendous, amounting to anywhere between 4.3 and 7.3 billion dollars each year. Despite the substantial financial burden of THA to the Canadian healthcare system, few studies have provided accurate cost estimations of this procedure.

Purpose: A lack of consensus regarding the radiologic criteria to diagnose spinal non-union limits inferences from clinical research. This systematic review aimed to examine the spectrum of radiologic investigations used to assess lumbar spinal fusion and the definitions of successful spine union used in the spine literature.

Method: We comprehensively searched three electronic databases from 1950 to 2009 (MEDLINE, Embase and the Cochrane Central Register of Controlled Trials) for clinical studies involving posterolateral fusion of the lumbar spine. English-language studies including adult patients and reporting a definition of successful fusion were included. Studies examining the reliability and validity of radiologic investigations were also identified. Key measures included

radiologic investigations,

Results: Among 1165 potentially eligible studies, 91 met our inclusion criteria. Of the studies 78% (n = 71) used plain radiographs to diagnose non-union, 4% (n = 4) used CT scans and 18% (n = 16) used both. Fifty-one studies used both static (xray or CT) and dynamic (flexion-extension xray) images, 35 used only static images and five used only dynamic radiographs. In total, we identified fifty-two different radiographic definitions of successful fusion. More than half of the studies (n = 50, 55%) failed to provide a reference for the definition used. The most common definition of fusion (7 studies) used static radiographs and defined fusion as continuous intertransverse bony bridging with this quality of fusion at all intended levels. Seven studies evaluated reliability of xray criteria but no studies provided complete validation of the definitions. Only 3 studies provided some validation and reliability estimates of thin-slice CT scanning in diagnosing spinal non-union. Significant variability in reliability, sensitivity and specificity exists for all radiologic investigations in the diagnosis of spinal non-union.

Conclusion: The radiologic investigations and definitions of successful posterolateral fusion used in the spine literature vary substantially. Choice of radiologic criteria should be based upon reliability and validity testing. Studies using fusion criteria that have not been shown to be reliable or valid should be interpreted with caution.