Stability of revision acetabular components using the rim-fit technique.

Use of the rim-fit technique in revision acetabular surgery was reviewed for 20 hips in 18 patients. Defects at revision surgery included isolated medial segmental and global cavitary deficiencies with largely intact peripheral rim. A cementless acetabular component is placed to achieve a press-fit against the bony acetabular rim after morselized allograft and/or autograft was placed behind the cup. The average follow-up period was 68.3 months (5.7 years) (range, 27-112 months). Cup migration was assessed using digital radiography. Average vertical migration was 1.02 mm superiorly, and average horizontal migration was 0.8 mm medially. The abduction angle changed on average by 0.25 degrees. Use of the rim-fit technique for treatment of cavitary acetabular defects is associated with component stability and minimal component migration.

Comparison and performance characteristics of 3 different knots when tied with 2 suture materials used for shoulder arthroscopy.

PURPOSE: To compare the performance of a standard suture material with that of a new material across several arthroscopic knot configurations. METHODS: Three knots were evaluated (Duncan loop, Weston, and San Diego knots) with the use of 2 suture materials (No. 2 Ethibond [Ethicon, Somerville, NJ] and No. 2 Force Fiber [Stryker Endoscopy, San Jose, CA]). Ten samples were tested for each knot and suture configuration. Samples were pretensioned to 10 N and were mechanically loaded from 10 to 45 N for 1,000 cycles. The number of cycles to 3 mm of loop elongation was recorded as "early" slippage. Intact knots with no evidence of early slippage were then subjected to a load-to-failure test so that the ultimate failure strength of the knot/material could be determined. RESULTS: Force Fiber knots required a statistically greater number of cycles to reach 3 mm of slippage compared with Ethibond knots (P < .0001). A single Force Fiber knot experienced 3 mm of displacement during cyclic loading; all others survived to 1,000 cycles. One third of all Ethibond knots were displaced to 3 mm during cyclic loading. For Ethibond sutures, no significant differences in ultimate failure strength were observed between knots (average, 143 N across knot types). For Force Fiber sutures, the San Diego knot (279 +/- 41 N) was statistically similar in ultimate failure strength to the Weston knot (254 +/- 41 N), but it was significantly stronger than the Duncan knot (224 +/- 70 N) (P < .03). CONCLUSIONS: The higher failure loads associated with Force Fiber may allow the surgeon to increase suture tension during knot tying, thereby creating a tighter knot. Loop elongation with Force Fiber occurred at loads that were greater than the typical breakage load for No. 2 Ethibond. Force Fiber is a new material that may be useful for various arthroscopic procedures. CLINICAL RELEVANCE: Force Fiber provided increased biomechanical stability compared with Ethibond regardless of knot type. The cost benefit of using very strong yet very stiff sutures must be clinically evaluated.