Objectives

An experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia.

Introduction

Acetabular cup positioning has been linked to dislocation and increased bearing surface wear. A previous study found correlations between patient and surgical factors and acetabular component position. The purpose of this study was to determine if acetabular cup positioning improves when surgeons receive feedback on their performance.

Objectives

This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone.

Purpose: The purpose of this study was to determine if correlation exists between acetabular cup positioning and factors relating to the surgeon and patient.

Method: Data for 2063 patients who underwent primary or revision THA from 2004 – 2008 were compiled. The post-op anteroposterior (AP) and cross-table lateral digital radiographs for each patient were obtained. The AP radiograph was measured using Hip Analysis Suite to calculate the cup abduction and version angles (version direction determined separately). Acceptable ranges were 35–45° for abduction, and 5–20° for version. Correlations were then determined with SPSS™ software.

Results: There were 1980(96%) qualifying patients. There were 1025(52%) acetabular cups that fell within the 35–45° abduction range, and 1287(70%) cups in the 5–20° version range. Regression analysis showed that the only independent predictor of acceptable abduction angle was the surgical approach (p< 0.001). Posterolateral approach was the most accurate (57% acceptability). In contrast to the posterolateral, the MIS (2 incision) approach was 3 times (95%C.I. 1.5–5, p=0.001), and the mini anterolateral approach 2.5 times (95%C.I. 1–6.5, p=0.035) more likely to have unacceptable abduction angles. The only independent predictor of acceptable version was the performing surgeon (p< 0.001), with higher volume surgeons showing greater accuracy.

Conclusion: The posterolateral approach was superior to MIS (2 incision) and mini anterolateral approaches for acceptable abduction angle, and surgeon volume influenced version angle acceptability. Further analysis on variables and their influence on cup position at a lower volume medical center would provide a valuable comparison.

There are a variety of patient and surgical factors shown to increase post-operative complication risk for a total hip arthroplasty (THA). While many studies have linked patient and surgical factors to unsuccessful outcomes post total hip arthroplasty (THA), no study has attempted to correlate the infiuence of these factors to the positioning of the acetabular cup. The purpose of this study was to determine if a correlation exists between patient and surgical factors and the anatomical position of the acetabular component.

Data for 2063 patients from 2004–2008 who underwent a primary total hip arthroplasty (THA), revision THA, or Birmingham Hip Resurfacing procedure was compiled. The post- op anteroposterior pelvis (AP) and the cross table lateral digital radiographs for each patient were measured to determine cup inclination and version. Acceptable angle ranges were defined as 30–45° for abduction, and 5–25° for version. Correlations between variables and cup abduction and version angles were determined with SPSS™ statistical software.

There were 1954(95%) qualifying patients. There were 1218(62%) acetabular cups that fell within the 30–45° optimal abduction range, and 1576(87%) cups in the 5–25° optimal version range. There were 921(47%) patients that had both inclination and version angles that fell within the optimal range. Regression analysis showed that surgical approach (p> 0.001), high/low volume surgeon (p< 0.001), and obesity (BMI > 30, p=0.01) were independent predictors for abduction and version combined analysis. Both surgical approach (p< 0.001) and BMI (p=0.018) were independent predictors in the individual analysis of both abduction and version. High/low volume surgeon was significant for the independent analysis of abduction (p=0.013). In the combined analysis, low volume surgeons showed a 2 fold increase (95% C.I. 1.5–2.8) in risk for cup malpositioning compared to high volume surgeons. The MIS surgical approach showed a 6 fold increase (95% C.I. 3.5–10.7) in risk for cup malpositioning compared to the posterolateral approach. Obesity (BMI> 30) showed a 1.3 fold increase (95% C.I. 1.1–1.7) in risk for cup malpositioning compared to all other body mass index groups.

Posterolateral surgical approach was superior to MIS surgical approaches for independent and combined abduction and version analysis. High volume surgeons had greater accuracy for cup positioning, specifically for achieving optimal cup abduction angle. Compared to all other body mass index categories, patients that were obese (BMI> 30) displayed a greater risk for cup malpositioning for independent and combined abduction and version analysis. Further statistical analyses on patient and surgical variables and their infiuence on cup position at a lower volume medical center would provide a valuable data comparison.

Several orthopaedic operations are encumbered with a high risk of infection. Early detection of such complication is of utmost importance for achieving good results.

From 1990 to 1998 a prospective study was done in 104 orthopaedic patients, who had a higher risk for postoperative infections. Diagnoses had been chronic osteomyelitis (47 cases), bone transplantation after osteomyelitis (19 cases), malignant bone tumors receiving chemotherapy (16 cases) and revision alloarthroplasty (22 cases). Consecutive levels of leucocytes in the wound drainages (deep and subcutaneus), white blood cell count (WBC) and c-reactive proteine (CRP) were analyzed.

Seventeen patients (septic group) were reoperated for suspected infection. The culture discount revealed Staphylococcus aureus (7 cases), Staphylococcus epidermidis (5 cases), Streptococcus hemoliticus (1 case), Mycobacterium tuberculosis (1 case), Enterococcus fae-calis (1 case), mixed organisms (2 cases), and histological signs of infection (4 cases). Comparing the aseptic and septic group no difference was noted for WBC < 2 days (p = 0.39), 2–3 days (p = 0.18), 3–6 days (p = 0.44) and > 6 days (p = 0.46). CRP difference was noted on the fourth day: mean 7.6 +− 0.8 mg/dl (range 6.0 to 9) (septic group); mean 5.9 +− 1.2 mg/dl (range 3.2 to 8.4) (aseptic group) (p < 0.001). The deep drainage leucocytes demonstrated to 12 hours: mean 5636 +− 2134 (range 2400 to 11200) (septic group) and mean 8531 +− 3312 (range 3100 to 18200) (aseptic group) (p < 0.001). 36 to 48 hours: the values changed adversely. 48 to 72 hours: mean 9146 +− 3666 (range 4700 to 16200) (septic group) and mean 2393 +− 879 (range 1100 to 4100) (aseptic group) (p < 0.001). The subcutaneus drainage leucoytes were 1.5 to 1.9 times higher (aseptic group) and 0.13 to 1.03 times lower (septic group) compared to the deep drainage.

We recommend deep drainage leucocytes monitoring 48 to 72 hours after the operation. Values greater 4100 (upper range of aseptic control) are suspicious and over 9146 (mean value of septic group) are strongly associated with an underlying wound infection.