Nonmechanical Failure Research Articles

What are the 5-year survivorship outcomes of compressive endoprosthetic osseointegration fixation of the femur?

Aseptic complications such as stress shielding leading to bone loss are major problems associated with revision of cemented and uncemented long-stem tumor endoprostheses. Endoprosthetic reconstruction using compressive osseointegration fixation is a relatively new limb salvage technology designed to enhance osseointegration, prevent stress shielding, and provide fixation for short end-segments. (1) What is the survivorship of this technique at minimum 5-year followup? (2) Were patient factors (age, sex, body mass index), oncological factors, or anatomic locations associated with implant failure? (3) Were there any prosthesis-related variables associated with failure? A single-center, retrospective review of patients with a minimum 5-year followup (mean, 8 years; range, 5-12 years) treated with an osseointegration compressive device for endoprosthetic fixation of proximal and distal femoral limb salvage reconstructions was performed. We have previously published the implant survivorship of this patient cohort with a minimum 2-year followup and are now reporting on the 5-year survivorship data. From 2002 to 2008, we performed 22 such procedures in 22 patients. Four patients died of their disease within 5 years of surgery and all surviving patients (n = 18) had complete followup data at a minimum of 5 years. General indications for this device during that time were pediatric and adult patients requiring primary endoprosthetic reconstructions of the proximal or distal femur for benign and malignant bone lesions. The primary outcome was reoperations for mechanical (aseptic) failures. Secondary outcomes included implant removal for nonmechanical failures and any patient-, oncological-, or implant-related variables associated with implant removal. At a minimum of 5 years followup, overall mechanical (aseptic) implant survivorship was 16 of 18. Survivorship for all modes of failure (oncological failure, infection, arthrofibrosis, and mechanical failure) was 12 of 18. All mechanical failures occurred early, within the first 30 months. We identified no patient-, oncological-, or implant-related features predictive of failure. Our intermediate-term experience with compressive osseointegration fixation for endoprosthetic limb reconstructions demonstrates with longer clinical followup, no additional mechanical failures were observed as compared with our early analysis. Our experience with this fixation at a minimum of 5-years followup adds to a very limited but increasing body of literature demonstrating that after a transient period of increased risk for implant failures, survivorship stabilizes. Assessment of this fixation strategy beyond 10 years of clinical followup is needed. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Comparison of Mechanical and Nonmechanical Failure Rates Associated With Rotating Hinged Total Knee Arthroplasty in Nontumor Patients

Rotating hinge total knee arthroplasty (TKA) has had acceptable to poor results in terms of clinical outcomes and survivorship, leading to skepticism with regard to its use. A total of 271 hinged TKAs performed between 1998 and 2008 were studied to determine survivorship and factors affecting survivorship. A median survivorship of 6.9 years was found for the best-case cohort (n = 111), and 4.1 years, for the worst-case group (n = 174). Of the 111 patients, 51 (45.9%) experienced a failure that required reoperation, with more than half of these (29/51, or 56.9%) due to nonmechanical modes of failure. Comparison of the kinematic hinge implants with the distal femoral replacements showed that the Kaplan-Meier survivorship was slightly higher for the patients with distal femoral replacements, although this was not significant (P = .962). Our study suggests that the hinge TKA is well designed and provides acceptable survivorship in healthy patients who do not have nonmechanical complications.

AMS 700CX/CXM Inflatable Penile Prosthesis Has High Mechanical Reliability at Long-Term Follow-Up

AMS 700CX/CXM inflatable penile prosthesis is increasingly applied for the treatment of erectile dysfunction (ED). However, there are a few long-term survival data of the inflatable penile prosthesis (IPP) over 10 years. To determine the long-term mechanical reliability of AMS 700CX/CXM inflatable penile prosthesis in patients with ED. A total of 438 consecutive patients with ED received implantation of an AMS 700CX/CXM penile prosthesis at our institution from January 1991 to April 2009. In 397 patients (90.7%), the medical records were available and current status of penile prosthesis could be obtained by a direct telephone interview. The overall and mechanical survival rates of penile prosthesis were evaluated using Kaplan-Meier method. Assessing the mechanical and overall survival rates of the AMS 700CX/CXM penile prosthesis using Kaplan-Meier analysis, and looking for clinical factors related to survival of the CX/CXM using log-rank test. Mean age of 397 patients was 63.1 years (range, 24-93) and follow-up duration was 113 months (range 1-219). Eighty-two patients (20.6%) experienced mechanical failure at a median follow-up of 82 months. Mechanical survival rate of the penile prosthesis was 97.6%, 93.2% and 78.2% at 3, 5, and 10 years after implantation, respectively. 12 patients (3.0%) experienced nonmechanical failure including infections, tissue erosion resulting in cylinder protrusion at the meatus and chronic discomfort. Overall survival rate of the penile prosthesis was 95.0%, 91.0% and 75.5% at 3, 5, and 10 years after implantation, respectively. Patients with neurogenic cause for ED showed lower median overall survival of penile prosthesis compared with patients with non-neurogenic cause. Patient age, obesity, and diabetes mellitus had no association with overall survival of penile prosthesis after implantation. The AMS 700CX/CXM could be accepted and applied in more patients as a reliable treatment alternative of ED.

OUTCOMES FOLLOWING REVISIONS AND SECONDARY IMPLANTATION OF THE ARTIFICIAL URINARY SPHINCTER

Durable success with the artificial urinary sphincter (AUS) is common but device revision and replacement are often needed for various reasons. We examined indications and outcomes following these secondary procedures with comparisons to outcomes after primary procedures. The medical records of all patients undergoing primary and secondary bulbar urethral AUS implantation and revision from January 1990 to September 2002 were reviewed for various demographic and surgical variables. Female patients and males with bladder neck cuffs were excluded from study. Of 554 men undergoing AUS implantation or revision 119 (21.4%) underwent a total of 159 secondary procedures. Reasons for revision were mechanical failure in 31 cases (25.2%) and nonmechanical failure in 88 (73.9%). The latter included recurrent incontinence due to urethral atrophy in 63 cases (52.9%) and erosion in 21 (17.6%). Total device replacement was performed in 75 cases (47.2%). Of 119 patients undergoing secondary implantation 91 (76.5%) needed no additional surgical intervention, while 28 (23.5%) required a total of 40 surgical revisions for new mechanical (15 or 37.5%) and nonmechanical (25 or 62.5%) problems. Five-year durability outcomes for primary and secondary AUS implantation were comparable at 80% and 88%, respectively. Similarly excellent continence outcomes (0 to 1 pad daily) were noted in 90% and 82% of patients undergoing primary and secondary AUS implantation, respectively. Secondary and tertiary AUS revisions resulted in the restoration of baseline continence in 106 cases (89%). Our study suggests that outcomes for secondary AUS reimplantation are comparable to those of primary AUS implantation and salvage of a good outcome is always probable, even following multiple prior revisions and cuff erosion.

SUCCESS OF DE NOVO REIMPLANTATION OF THE ARTIFICIAL GENITOURINARY SPHINCTER

We evaluate our experience with de novo reimplantation of the artificial genitourinary sphincter with a particular emphasis on mechanical and nonmechanical failure rates. De novo reimplantation is defined as implantation of an artificial sphincter following removal of a previously placed sphincter for erosion and/or infection and a waiting period of several months. A retrospective analysis of more than 400 patients with an artificial sphincter revealed 23 who underwent de novo reimplantation between January 1983 and October 1998. All patients were men with a mean age of 66.5 years (range 16 to 88) and all had a urethral cuff. Reasons for cuff removal were erosion in 12 cases (52.2%), infection in 10 (43.5%) and intraoperative urethral injury in 1 (4.3%). Mean waiting period was 6.8 months (range 1.5 to 32) between explantation and de novo reimplantation. Mean followup was 32.6 months (range 1 to 108). Of the 23 patients 20 (87%) had no mechanical or nonmechanical failures and 3 (13%) had nonmechanical failures, including 2 patients (8.7%) whose cuff eroded into the urethra and 1 (4.3%) who had recurrent urinary incontinence which was successfully treated with implantation of a tandem cuff. There were no mechanical failures or infections in this group of patients. Our study suggests that de novo artificial sphincter reimplantation is an excellent treatment option. It is safe and associated with complication rates that are comparable to those of primary implantation.

MAYO CLINIC LONG-TERM ANALYSIS OF THE FUNCTIONAL DURABILITY OF THE AMS 800 ARTIFICIAL URINARY SPHINCTER: A REVIEW OF 323 CASES

Purpose We determine the long-term durability of the AMS 800′ artificial urinary sphincter in the correction of severe urinary incontinence, and evaluate mechanical versus nonmechanical failure and reoperation rates before (1983 to 1987) and after (1988 to present) the introduction of the narrow backing occlusive cuff design. ' American Medical Systems, Inc., Minnetonka, Minnesota. Materials and Methods From January 1983 to October 1994 more than 400 patients received an AMS 800 artificial urinary sphincter placed by 1 surgeon and 323, mean age 60.4 years, met study requirements for review. Mean followup was 68.8 months (range 18 to 153). Only patients with a minimum of 18 months of followup were included in the study. Of the 313 men and 10 women in the study group sphincters were placed at the urethra in 272 and at the bladder neck in 51. All patients were followed from surgery to the date of sphincter failure. Etiology of the failures was recorded and divided into mechanical versus nonmechanical sphincters placed before and after the introduction of the narrow backing cuff. Results Overall, 58 of the 139 patients (42%) in the pre-narrow backing cuff group versus 31 of the 184 (17%) in the narrow backing cuff group required a first reoperation. Mechanical failure occurred in 29 cases (21%) with the pre-narrow backing and 14 (7.6%) with the narrow backing cuff. Nonmechanical failure developed in 24 cases (17%) with the pre-narrow backing and 17 (9%) with the narrow backing cuff. Ultimately 437 operations were required in the 323 patients, of whom 234 (72%) required no further surgical intervention at a mean followup of 68.8 months. Conclusions Technological advances in the design and construction of the AMS 800 have dramatically decreased the reoperation and failure rates. These advances and improved surgical techniques provide an excellent long-term solution and increased continence in correctly selected patients with urinary incontinence.