A Fully Functional Drug-Eluting Joint Implant.

Despite advances in orthopedic materials, the development of drug-eluting bone and joint implants that can sustain the delivery of the drug and maintain the necessary mechanical strength in order to withstand loading has remained elusive. Here, we demonstrate that modifying the eccentricity of drug clusters and the percolation threshold in ultrahigh molecular weight polyethylene (UHMWPE) results in maximized drug elution and in the retention of mechanical strength. The optimized UHMWPE eluted antibiotic at a higher concentration for longer than the clinical gold standard antibiotic-eluting bone cement while retaining the mechanical and wear properties of clinically used UHMWPE joint prostheses. Treatment of lapine knees infected with Staphylococcus aureus with the antibiotic-eluting UHMWPE led to complete bacterial eradication and to the absence of detectable systemic effects. We argue that the antibiotic-eluting UHMWPE joint implant is a promising candidate for clinical trials.

An electronic database for outcome studies that includes digital radiographs.

We report on acquisition of key data from the clinical medical record, surgical data, radiologic studies, and patient surveys for a novel digital total hip arthroplasty (THA) registry that includes electronic capture of digital radiographic images into a database on an internet platform for query. We now have the ability to collect demographic and operative data, including the operative note, discharge summary, surgery data, and Digital Imaging Communications in Medicine (DICOM) radiology images. Steps are being completed to assemble office encounters, hospital procedural codes, and implant bar codes. Two examples include a THA surgery record and a THA outcome study with plain radiograph set. Analysis of such data could suggest ways to improve clinical practice.

Infected total knee arthroplasty treated with arthrodesis using a modular nail.

Failed treatment of infected total knee replacement presents few attractive surgical options. Knee arthrodesis is challenging surgically and can be complicated by nonunion, malunion, or recurrent infection. Recently, a modular titanium intramedullary nail has been used in an attempt to reduce the incidence of nonunion and the rate of complications. In the present study, a review of the results of knee arthrodesis after infected total knee arthroplasty in 21 patients at three large academic institutions was performed. All patients were followed up for a mean of 2.4 years (range, 2-7.5 years). The mean age of the patients was 64 years. The mean number of previous operations was four (range, 2-9 operations). A solid arthrodesis was achieved without additional surgical treatment in 20 of 21 patients (95%). The mean time to fusion was 6.3 months. The one patient who suffered a nonunion achieved fusion after a subsequent bone grafting procedure. Based on the present study, intramedullary arthrodesis with a coupled titanium nail, is a reliable, effective method of achieving fusion after infection of a total knee arthroplasty. This procedure resulted in a high rate of fusion and a lower rate of complications when compared with traditional methods of arthrodesis.

An international comparative study of total hip arthroplasty cost and practice patterns.

The cost of total hip arthroplasty (THA) was assessed on a worldwide basis, with specific information obtained regarding implant type, cost, manufacturer, fixation method, as well as other clinical related practices. One hundred and ten orthopaedic surgeons representing 30 countries and 6 continents responded to the questionnaire. The average number of THAs per year per surgeon was 75 (range, 2-300). Surgeons reported using all cemented components in 35% of THAs at an average cost of $1,536 (U.S. dollars). Uncemented components were used in 31% at an average cost of $2,674, and hybrid reconstructions in 34% at an average cost of $2,114. Almost half (44%) of the respondents stated that the hospital negotiated the type and price of the implants. Most surgeons (80%) indicated they were under pressure to decrease the cost of THA and 68% were under pressure to reduce the length of patients' hospital stay. When asked for recommended ways to reduce costs, 30% stated that negotiating a reduced implant price from the supplier was the most important measure. On a worldwide basis, there is tremendous variation in the cost and availability of implants. The reported cost for identical implants from a single manufacturer can vary as much as 700%. The comments of those responding are similar to the findings of surgeons here in the United States regarding cost containment and the role of reducing the length of hospital stay as well as negotiating reduced prosthesis and supply costs. The orthopaedic surgeon's practice pattern is a major determinant of total costs.

Enhancement of the value of hip questionnaires by telephone follow-up evaluation.

Errors, omissions, false understanding, and contradictory answers can compromise the use of questionnaires to generate follow-up data. To assess the utility of and effort involved in adding routinely a telephone interview to clarify the questionnaire, a study of total hip arthroplasty patients was carried out. Thirty-six patients with 37 primary and 13 revision total hip arthroplasties filled out a standardized questionnaire (which asks a number of demographic questions as well as questions that allow calculation of the Medical Outcome Studies [MOS] 36-Item Short-form Health Survey [SF-36], Western Ontario MacMaster Arthritis Center [WOMAC] osteoarthritis index, and Harris hip score) prior to returning for routine follow-up evaluation a minimum of 1 year after surgery. Two hundred thirty-two of a possible 4,350 responses (5.3%) were missing, contradictory, or answered with two or more answers on the questionnaire. Only eight such defects occurred following the telephone interview by a skilled orthopaedic surgeon, representing a significant reduction in these defects (P < .005). The average time of the telephone call was 2.8 minutes (range, 1-12 minutes), and the average number of attempts to contact the patient was 1.4 (range, 1-6). All questionnaire data and questionnaire data plus telephone data were compared with data obtained from a subsequent face-to-face interview by a different skilled orthopaedic surgeon who was blinded to the data from both the questionnaire and the telephone interview. It is demonstrated that a telephone call to follow up a standardized, self-administered questionnaire is a very effective way to augment the quality and quantity of questionnaire responses.

An ultrasound method to evaluate polyethylene component wear in total knee replacement arthroplasty.

Evaluation of a painful total knee replacement has been limited to physical examination, aspiration, plain radiographs, and radionuclide studies. Visualization of the polyethylene tibial-bearing component without surgery has not been possible. Polyethylene wear is a well-recognized cause of total knee replacement failure. We have developed an ultrasound method to evaluate polyethylene insert shape and thickness with the ability to clearly demonstrate structural loss of plastic. Before clinical trials, a total knee replacement was cemented into a fresh cadaver knee. Ultrasound imaging of the polyethylene insert was performed in the longitudinal plane using a 10 MHz linear transducer. A characteristic bone/metal/polyethylene interface enabled recognition of the insert material from which its dimension was estimated. The entire perimeter of the liner, the metal tray, and the bone-metal interface was visualized. Five consecutive measurements at each location were performed on each of the 8-, 10-, and 12-mm polyethylene liners with the ultrasonographer blind to the insert thickness. Once removed, measurements were made directly on the liners adjacent to the marked points with an electronic caliper. Coefficient of variation (r2) ranged from 1.6% to 8.3% for the ultrasound measurements, and 0.26% to 1.5% for the caliper measurements. A plot of ultrasound versus caliper measurements allowed calculation of a linear equation, with r2 = 0.98, demonstrating high correlation between the two measurements. Our ultrasound measurements are accurate to 0.5 mm with a 95% confidence interval. Ultrasound is an accurate way to measure the dimensions of the polyethylene liner in total knee replacement arthroplasty. Early experiences with ultrasound evaluation prior to revision have been very encouraging for the evaluation of polyethylene wear, defects, and of prosthetic loosening.

Correlation of measured range of hip motion following total hip arthroplasty and responses to a questionnaire.

Twenty-eight patients (with 30 primary and 8 revision total hip arthroplasties) completed a standardized questionnaire containing the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and Harris hip score questions prior to an office visit a minimum of 1 year after surgery. The range of hip motion measured by an orthopaedic surgeon was compared with the responses to questions on stiffness and function as well as with global scores in the WOMAC osteoarthritis index. Patient responses to the questions asking if they could cut their toenails on the operated side and the Harris hip score question asking if they could put on socks and tie a shoe correlated significantly with postoperative hip motion (P < .005). The WOMAC global pain and stiffness scores did not correlate with range of motion. The WOMAC physical function score correlated significantly only with hip flexion (P < .05). Of the WOMAC physical function questions, difficulty bending to pick an object off the floor (P < .05) and getting on and off the toilet (P < .05) correlated with the sum of the range of motion in all planes and weighted Harris hip score range of motion calculation. These data suggest that the points allocated in the Harris hip score for range of motion can be estimated reasonably accurately from questionnaire or phone response to a series of questions on a standardized questionnaire. The question on ability to cut toenails or the Harris hip score question regarding ability to put on socks and tie a shoe correlated with the most individual planes of motion, but several WOMAC physical function questions also correlated with total and weighted range of motion calculations.

Malignant melanoma of the foot and ankle.

The records of sixty patients who had a malignant melanoma of the foot or ankle were reviewed retrospectively to determine the clinical features, prognostic factors, and distinguishing characteristics. Fifty-seven patients were white and three were black. There were forty-two women and eighteen men (a female-to-male ratio of 2.3 to 1). The mean age at the time of presentation was fifty-seven years (range, twenty-two to eighty-three years). The most common site of involvement was the plantar aspect of the foot. The mean duration of follow-up was forty-five months (range, three to 144 months). Kaplan-Meier life-table analysis revealed an over-all five-year survival rate of 63 per cent and an over-all ten-year survival rate of 51 per cent. The mean duration of survival for the patients who had a plantar or subungual lesion was significantly shorter than that for the patients who had a lesion at another site on the dorsal aspect of the foot or on the ankle (forty-seven compared with seventy-two months) (p = 0.02). The mean depth of the lesion, according to the criteria of Breslow, was 3.03 millimeters, and the mean level, according to the classification of Clark et al., was IV. According to the classification of the American Joint Commission on Cancer, forty-three patients had stage-I or II (local) disease, thirteen had stage-III disease (nodal or in-transit disease, defined as cutaneous or subcutaneous metastases more than two centimeters from the primary tumor but not beyond the regional lymph nodes), and four had stage-IV disease (distant visceral metastases) at the time of presentation. Lesions at plantar and subungual sites were also associated with a higher prevalence of clinical misdiagnosis compared with lesions on the dorsal aspect of the foot or on the ankle (p = 0.02). The misdiagnoses included a benign nevus (one patient), a paronychia (one patient), a pyogenic granuloma (two patients), a plantar wart (three patients), a ganglion cyst (one patient), a blister (two patients), and a traumatic lesion (five patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of patellar allograft to reconstruct a patellar tendon-deficient knee after total joint arthroplasty.

A catastrophic complication after total knee arthroplasty (TKA) is rupture of the patellar tendon. Several techniques for treatment have been described, including cast immobilization with or without operative repair, the use of a semitendinosus, fascia lata, or hamstring tendon autogenous graft, the use of a Dacron 4-mm vascular graft (U.S. Catheter and Instrument, Glen Falls, NY), the use of bovine xenograft and even transplantation of an entire allograft extensor mechanism. Treatment results of patellar tendon rupture after TKA can be discouraging. Altered tissue quality secondary to connective tissue diseases, diabetes, rheumatoid arthritis, lupus erythematosus, secondary hyperparathyroidism, or concurrent steroid medications contributes to poor results. Additionally, no one treatment has provided consistent clinical success. Successful treatment of a patient with a ruptured patellar tendon after TKA using the bone-patellar tendon-bone allograft commonly used for anterior cruciate ligament reconstruction is reported.

The femoral stent. Surgical technique for a new method of cementing the femoral component in the presence of a large cortical defect.

Modern cement technique consists of the use of porosity reduction of the cement, a femoral medullary canal plug, injection of the cement using a cement gun, centralization of the stem, and pressurization of the cement. The use of cement in femoral revision is increasing rapidly; however, when there is a major cortical defect, forming and pressurizing the cement column might appear impossible. We describe a surgical technique for sealing such defects with a custom-made, intraoperatively fashioned femoral stent that allows for temporary restoration of the cortical tube of the femur, and therefore full pressurization of the cement.

The use of a high-hip center in revision total hip arthroplasty.

In certain cases, primary and revision total hip arthroplasty is complicated by insufficient bone stock and distorted acetabular anatomy such that the craniocaudal dimension of the acetabular recess is greater than the anteroposterior dimension. Acetabular reconstruction in such cases can be carried out by placing the acetabular component more proximally than normal (high-hip center). Recent biomechanical and clinical data suggest that placement of the acetabular component at a higher than normal hip center does not adversely effect the longevity of the component fixation. Proximal placement of the hip center also facilitates the contact between the host bone and the porous coating when uncemented porous coated components are used, and minimizes the need for structural bone grafts. However, femoral components with longer neck lengths and removal of impinging bone are needed when the acetabular components are placed more proximally in order to restore the limb lengths and minimize the chances for dislocation.

Aneurysmal bone cysts in young children.

We reviewed seven young children (< or = 10 years) with aneurysmal bone cysts. There were four girls and three boys. Six had involvement of the long bones and one had involvement of the clavicle. The average age was 5.5 years (range 2.9-10.6 years). Initial treatment was curettage and bone grafting. There were recurrences in five of the seven children (71%). This represented 100% of children with radiographically aggressive or active lesions. The recurrences appeared rapidly, at an average of 8 months from the first procedure. The mitotic index of the initial lesion did not correlate with that of the recurrent lesion. Surgical management of the recurrences must be handled individually, but repeat curettage and grafting is only recommended when surgical resection is not possible. This high rate of recurrence in radiographically aggressive or active aneurysmal bone cysts in young children should be considered when planning treatment, and in the preoperative counseling of parents.

Metastatic vertebral disease in children.

We retrospectively reviewed 19 children with osseous vertebral metastases. The average age was 10.9 years at diagnosis of the primary tumor and 11.2 years at diagnosis of metastasis. The location of the multiple metastases was cervical (three), thoracic (14), and lumbar (10). Treatment consisted of chemotherapy (19), radiation therapy (12), and operation (seven). Ten children died at an average of 13 months after diagnosis of the primary tumor; nine are alive at an average of 72 months after diagnosis. All four children treated with chemotherapy, spinal radiation, and laminectomy, and who survived > 2 months, developed deformity. In this particular situation, we encourage consideration of spinal stabilization when it is appropriately coordinated with radiation and chemotherapy.

Thorn synovitis of the knee joint with Nocardia pyarthrosis.

Pyarthrosis of the knee with Nocardia asteroides occurred concomitantly with thorn synovitis in an 11-year-old boy who was otherwise healthy. A review of the orthopedic and infectious disease literatures did not disclose a similar report. Contrary to common teaching, effusions from joints violated by thorns should not be presumed sterile. Culture for bacterial and fungal infections is recommended when treating cases of thorn synovitis.

Hand manifestations of oxalosis.

Oxalosis is an unusual metabolic disease that results either from an inherited hepatic enzyme deficiency or as the result of poor oxalate clearance during chronic hemodialysis. We present two cases of oxalosis and describe the hand manifestations of this condition and their treatment. One patient had painful, progressive gangrene, whereas in the other the disease took an indolent course with small palmar crystalline deposits.