Effect of Medial Osteophyte Removal on Correction of Varus Deformity in Total Knee Arthroplasty

BACKGROUND

To restore neutral limb alignment in total knee arthroplasty (TKA), the procedure usually starts with removing osteophytes in varus osteoarthritic knees. However, the exact effect on alignment correction is unknown. The purpose of this study was to determine the effect of osteophyte removal alone during TKA for varus knees on correction of limb alignment on the coronal plane.

METHODS

Fifteen knees with medial osteoarthritis and varus malalignment scheduled for TKA were studied. After registration in a navigation system, each knee was tested at maximum extension, and at 30, 40, and 60 degrees of flexion, before and after osteophyte removal. External loads of 10 N·m valgus torque at each angle and in both states were applied. Later, the widths of the resected osteophytes were measured.

RESULTS

The average preoperative hip-knee-ankle angle was -14.2 degrees. The average width of osteophytes was 7.6 mm in the femur and 5.3 mm in the tibia. Angle corrections after osteophyte removal were 3.4 degrees at maximum extension, 3.4 degrees at 30 degrees flexion, and 3.6 degrees at 60 degrees flexion; the difference was significant for all angles. There was a positive correlation between osteophyte width and the degree of angle correction at 30 degrees.

CONCLUSION

At 30 degrees of knee flexion, osteophyte width was correlated with the degree of angle correction on the coronal plane in TKA. The degree of angle correction per 1 mm of width of removed osteophytes was 0.4 degrees.

Doppler Velocity Estimates of Internal Carotid Artery Stenosis: Angle Correction Parallel to the Color Doppler Lumen Versus Parallel to the Artery Wall

OBJECTIVES

We compared internal carotid artery Doppler peak systolic velocities (PSVs) measured with angle correction parallel to the artery wall (// wall) on grayscale images and parallel to the direction of blood flow (// flow) on color Doppler images.

METHODS

We studied 25 internal carotid lesions with PSVs higher than 125 cm/s. The PSVs were measured in the same imaging plane, at the stenosis orifice (0 cm) and at 0.5 and 1 cm downstream by both methods. Linear regression and correlation analyses were used to study the effects of the angle correction method on changes in PSVs as a function of the differences in angle adjustment and distance from the stenosis.

RESULTS

The 23 patients studied included 9 women and 14 men. There was a mean difference in absolute PSVs ± SD of -17.2 ± 29.5 cm/s (P < .008) between methods at the stenosis. The difference in the PSVs was associated with the angle difference between the flow jet and the artery wall (P < .01). At 1 cm from the stenosis, // flow PSVs were more strongly correlated with PSVs at the stenosis (r = 0.61; 95% confidence interval, 0.28, 0.82; P = .001) than // wall PSVs (r = 0.39; 95% confidence interval, -0.003, 0.68; P = .052).

CONCLUSIONS

Blood flow velocity measurements made with angle correction parallel to the direction of the color Doppler blood flow lumen remain more consistent with the distance from the stenosis than blood flow velocity measurements made with angle correction parallel to the outer artery walls.

Utility of Angle Correction for Hemodynamic Measurements with Doppler Echocardiography

OBJECTIVES

The routine application angle correction (AnC) in hemodynamic measurements with transesophageal echocardiography currently is not recommended but potentially could be beneficial. The authors hypothesized that AnC can be applied reliably and may change grading of aortic stenosis (AS).

DESIGN

Retrospective analysis.

SETTING

Single institution, university hospital.

PARTICIPANTS

During phase I, use of AnC was assessed in 60 consecutive patients with intraoperative transesophageal echocardiography. During phase II, 129 images from a retrospective cohort of 117 cases were used to quantify AS by mean pressure gradient.

INTERVENTIONS

A panel of observers used custom-written software in Java to measure intra-individual and inter-individual correlation in AnC application, correlation with preoperative transthoracic echocardiography gradients, and regrading of AS after AnC.

MEASUREMENTS AND MAIN RESULTS

For phase I, the median AnC was 21 (16-35) degrees, and 17% of patients required no AnC. For phase II, the median AnC was 7 (0-15) degrees, and 37% of assessed images required no AnC. The mean inter-individual and intra-individual correlation for AnC was 0.50 (95% confidence interval [CI] 0.49-0.52) and 0.87 (95% CI 0.82-0.92), respectively. AnC did not improve agreement with the transthoracic echocardiography mean pressure gradient. The mean inter-rater and intra-rater agreement for grading AS severity was 0.82 (95% CI 0.81-0.83) and 0.95 (95% CI 0.91-0.95), respectively. A total of 241 (7%) AS gradings were reclassified after AnC was applied, mostly when the uncorrected mean gradient was within 5 mmHg of the severity classification cutoff.

CONCLUSIONS

AnC can be performed with a modest inter-rater and intra-rater correlation and high degree of inter-rater and intra-rater agreement for AS severity grading.