Sat., 10/10/09 Knee/Tibia, Paper #81, 3:52 pm OTA-2009
Technical Difficulties in Removal of the Less Invasive Stabilization System (LISS)
Takashi Suzuki, MD (n); David J. Hak, MD (n); Wade R. Smith, MD (n);
Philip F. Stahel, MD (n); Andrea J. Baron, MS (n); Steven J. Morgan, MD (n);
Denver Health Medical Center, Denver, Colorado, USA
Purpose: Titanium locking plates have the known problem of cold welding that can significantly complicate subsequent plate removal. The purpose of this study was to evaluate the frequency of screw removal difficulty and the perioperative complications during Less Invasive Stabilization System (LISS, Synthes) plate removal.
Methods: We performed a retrospective review of patients who underwent LISS plate removal at a Level 1 trauma center between January 2002 and December 2008. Medical records were reviewed for demographics, surgical technique, plate length, number and position of screws, time from internal fixation to plate removal, reason for removal, operating time for removal, and perioperative complications. Pre- and postoperative radiographs were also reviewed to confirm plate and screw positions. The independent factors, including age, sex, plate site, plate screw density, reason for removal, and time from internal fixation to removal, were compared between patients in whom screw removal was complicated and those in whom screw removal proceeded without difficulty. Mann-Whitney and Fisher exact tests were calculated with the level of significance at P <0.05.
Results: 33 patients (24 male and 9 female) underwent plate removal from 36 extremities (15 tibias and 21 femurs). The average age at the time of removal was 44.9 years. The average time from internal fixation to removal was 13.2 months. The plates removed were: 13-hole plates (16 cases), 9-hole plates (18 cases), and 5-hole plates (2 cases). The reasons for plate removal were: symptomatic hardware after bone union (21 cases), nonunion requiring additional fixation (12 cases), early loss of fixation (2 cases), and a peri-implant fracture (1 case). Minimally invasive techniques including percutaneous insertion of the LISS plate were used in 33 cases. The average operating time for plate removal was 71.3 minutes (range, 28-180). Five cases required more than 120 minutes. Of the 349 screws that were removed, 185 screws were from the metaphyseal region and 164 screws were from the diaphysis. Difficulty with screw removal was encountered in 37 screws (10.6%) from 14 cases (38.9%). Two plates and 11 screw heads were cut using a carbide or diamond-tipped burr. Six cases required levering off the plate with 10 screws still attached. Five screws were cut using a large bolt cutter. The other screws were stripped but not cold welded and were removed with a stripped screw removal tap. Nine patients required full open surgical approach to remove the plate. Three patients who had originally been scheduled for outpatient surgery ultimately required hospitalization due to the prolonged and extensive plate removal operation. Two patients developed a postoperative superficial wound infection that was treated with oral antibiotics. There were no statistical differences in predictors for patients with screw removal difficulty.
Conclusion: Difficulty with removal due to cold welding or screw head stripping is common in locking LISS plate screws. LISS plate removal can often require prolonged operating time and the use of specialized removal tools. Surgeons should anticipate the possibility of difficulties in hardware removal and be appropriately prepared.
Disclosure: (n=Respondent answered 'No' to all items indicating no conflicts; 1=Board member/owner/officer/committee appointments; 2=Medical/Orthopaedic Publications; 3=Royalties; 4=Speakers bureau/paid presentations; 5A=Paid consultant or employee; 5B=Unpaid consultant; 6=Research or institutional support from a publisher; 7=Research or institutional support from a company or supplier; 8=Stock or Stock Options; 9=Other financial/material support from a publisher; 10=Other financial/material support from a company or supplier).
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant