[show abstract][hide abstract] ABSTRACT: Long-term survival of distal femoral endoprosthetic replacements is largely affected by aseptic loosening. It is unclear whether and to what degree surgical technique and component selection influence the risk of loosening.
We (1) established the overall failure and aseptic loosening rates in a tumor population and asked (2) whether stem diameter and specifically the diaphysis-to-stem ratio predicts loosening, and (3) whether resection percentage correlates with failure.
We retrospectively reviewed the charts of all 93 patients in whom 104 distal femoral replacements had been performed from 1985 to 2008. We extracted the following data: age, need for revision surgeries, tumor diagnosis, adjunct treatment, and implant characteristics. We reviewed radiographs and determined stem size, bone diaphyseal width, and resection percentage of the femur. Kaplan-Meier survivorship was calculated for all implant failures and failures resulting from aseptic loosening. We evaluated radiolucent lines in patients with radiographic followup over 5 years. We identified independent risk factors for loosening. The minimum followup for radiographic evaluation was 5 years (mean, 12.7 years; range, 5.4-23.5 years).
Overall implant survival for 104 stems in 93 patients was 73.3% at 10 years, 62.8% at 15 years, and 46.1% at 20 years. Survival from aseptic loosening was 94.6% at 10 and 15 years and 86.5% at 20 years. Of the variables analyzed, only bone:stem ratio independently predicted aseptic failure. Patients with stable implants had larger stem sizes and lower bone:stem ratios than those with loose implants (14.5 mm versus 10.7 mm and 2.02 versus 2.81, respectively).
Our data suggest durability relates to selecting stems that fill the canal.
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
Clinical Orthopaedics and Related Research 03/2012; 470(3):743-50. · 2.79 Impact Factor
[show abstract][hide abstract] ABSTRACT: Postoperative spine infections cause considerable morbidity. Patients are subjected to long-term antibiotic regimens and may require further surgery. Delivery of electric current through instrumentation can detach biofilm, allowing better antibiotic penetration and assisting in eradicating infection. QUESTION/PURPOSES: We asked (1) whether capacitive coupling treatment in combination with a single dose of antibiotics would reduce infection rates when compared with antibiotics alone in a rabbit spine infection model, (2) whether it would decrease the overall bacterial burden, and (3) whether there was a time-dependent response based on days treated with capacitive coupling.
Thirty rabbits were subjected to a well-established spine infection model with a single dose of intravenously administered systemic ceftriaxone (20 mg/kg of body weight) prophylaxis. Two noncontiguous rods were implanted inside dead space defects at L3 and L6 challenged with 10(6) colony-forming units of Staphylococcus aureus. Rabbits were randomly treated with a capacitive coupling or control device. Instrumentation and soft tissue bacterial growth were assessed after 7 days.
Sites treated with capacitive coupling showed a decrease in the incidence of positive culture: 36% versus 81% in the control group. We observed no difference in the soft tissue's infectious burden. Overall bacterial load was not decreased with capacitive coupling.
Capacitive coupling in conjunction with antibiotics reduced the instrumentation-related infection rate compared with antibiotics alone.
Capacitive coupling noninvasively delivers an alternating current that may detach biofilm from instrumentation. Treatment of infection may be successful without removal of instrumentation, allowing for improved stability and overall decreased morbidity.
Clinical Orthopaedics and Related Research 01/2012; 470(6):1646-51. · 2.79 Impact Factor
[show abstract][hide abstract] ABSTRACT: While complications following massive endoprosthetic reconstruction have been previously described, the incidence and effects of these complications over extended periods of time have not been well characterized in large series.
We therefore determined: (1) incidence and types of complications; (2) relative risk of complications; (3) likelihood of secondary complications; (4) whether modularity altered such complications; (5) implant failure and limb salvage rates and (6) implant survival over extended followup.
We retrospectively reviewed 232 patients (241 implants: 50 custom,191 modular) who underwent endoprosthetic reconstruction for malignant and aggressive bone tumors between 1980 and 2002. Complications were classified as infection, mechanical, superficial soft tissue, deep soft tissue, or dislocation. Survival was determined by Kaplan-Meier analysis. Minimum followup was 5 years (mean: 10 years; range: 5-27 years).
One hundred thirty-seven of 232 patients (59%) underwent a single reconstruction. Ninety-five patients had 242 additional procedures. Forty-four revised patients retained their original prosthesis. Limb salvage rate was 90%; implant failure (removal of the cemented part) was seen in 29% (70/241) with a median survival of 190 months. Twenty-five of 50 custom implants failed (8 then failed again) while 30/180 modular implants failed (7 then failed again). Of 70 instances of implant failure, 38/70 were mechanical, 27/70 infectious. Risk of infection increased 30% after a second procedure; 16 of 24 amputations were performed because of infection.
Mechanical complications were the most common cause of implant failure. Infection was the leading cause of both complication and amputation; risk of infection increased substantially with revision surgery. Modular implants had fewer mechanical complications, thus leading to fewer revisions and subsequent infections.
Clinical Orthopaedics and Related Research 11/2010; 468(11):2885-95. · 2.79 Impact Factor