Bone ingrowth into a porous-coated total shoulder component retrieved postmortem.

An uncemented porous-coated humeral component, which functioned in vivo for over 2 1/2 years, was retrieved postmortem and examined histologically. Radiographs of the specimen revealed close approximation to the endosteal cortex medially and laterally. Apposition was limited or absent anteriorly and posteriorly. The overall extent of bone ingrowth was approximately 11% of the available pore volume with over 95% of ingrowth occurring in the medial and lateral quadrants. Bone ingrowth was limited anteriorly and posteriorly to regions in which spot welds were identified radiographically. There were no loose beads or coating failure observed.

Wrist arthroplasty: a retrospective study.

A retrospective study was conducted to evaluate the long-term effectiveness of wrist arthroplasties in patients with various arthritic conditions. A total of 39 wrist arthroplasties were performed in 29 patients (average age, 52.5 years) by the orthopedic staff at Tulane University School of Medicine. Rheumatoid arthritis was the major presenting diagnosis in 84.6% of these operative cases and pain was the most common indication for surgery (79.5%). Postoperative relief of pain was reported in all of the cases reviewed, with an average follow up period of 51.2 months (range, 12 to 118 months). A group of 15 patients who were examined clinically had an average grip strength of 19.2 lb (range, 6 lb to 45 lb). Pinch measurements averaged 1.9 lb and arc of motion averaged 59.5 degrees (range, 20 degrees to 100 degrees) for these patients. Postoperative complications included dislocation (3 cases), fracture of the prosthesis (2 cases), and infection (2 cases). No complications were observed in 32 (82.1%) of the 39 cases reviewed. This retrospective study revealed that at an average follow up period of 51.2 months, pain relief was excellent and patient acceptance was good, with 94.9% of the wrists having been improved by the procedure. The majority (82.1%) of the cases were free of complication. It is concluded from this study that wrist arthroplasty is a viable alternative to wrist arthrodesis.

Upper cervical ossicles in Down syndrome.

Six patients with upper cervical spine ossicles and Down syndrome from a study population of 184 are described. The average age was 20.6 years at the time of diagnosis. Three of the patients were involved in tumbling. Radiographic anatomy of the ossicles and the dens, as well as serial radiographs in three of the six patients, suggest that this represents an avulsion of the upper end of the dens rather than an occipital vertebrae, ossiculum terminale, or os odontoideum, as previously described. The authors advocate restriction of high-risk activities for all patients with Down syndrome.

The effect of the radial head and prosthetic radial head replacement on resisting valgus stress at the elbow.

Five fresh nonembalmed elbows were tested for resistance to valgus stress in their anatomic state, after radial head resection, and after insertion of Silastic and polymethylmethacrylate (PMMA) radial head replacements. The resistance to valgus stress was found to be reduced an average of 28% after radial head resection. The PMMA and Silastic implants restored valgus stiffness an average of 86% and 78% respectively, as compared to intact elbow values for corresponding flexion angles. Testing in pronation, supination and neutral forearm rotation demonstrated no difference in valgus stiffness. For each elbow, resistance to valgus stress was greatest at full extension and dropped approximately 30% at all other flexion angles as compared to corresponding full extension value. These data support the concept of the radial head as a stabilizer to valgus stress in the in vitro elbow. Further, this data demonstrated the ineffectiveness of current radial head replacement systems in restoring this biomechanical function and suggest that the use of a stiffer implant material may be beneficial in resisting valgus stress. Additional testing is indicated to determine the performance of a stiffer implant at the clinical and biological levels.

Chronic atlanto-axial instability in Down syndrome.

We studied the radiographs of thirty-two patients with Down syndrome for evidence of atlanto-axial instability. One of the patients had instability in 1970 and seven had it in 1983. The interval between the atlas and the odontoid process in the patients who demonstrated motion at that interval radiographically averaged 2.78 millimeters in 1970 and 6.93 millimeters in 1983 (p less than 0.005). Four patients whose radiographs showed atlanto-axial motion in 1970 lost that motion by 1983, and in seven patients who did not show atlanto-axial instability in 1970 it developed by 1983. Atlanto-axial instability was more likely to develop in boys who were more than ten years old. Accessory upper-cervical ossicles became evident in three patients, none of whom had atlanto-axial motion. However, one of these three patients had an abnormally wide atlanto-axial interval.

Early, design-related failure in total knee arthroplasty a case report.

The analysis of retrieved implant devices can provide information unavailable through any other method. With the variety of implant designs rapidly increasing, retrieval and analysis of failed cases is an important means of evaluating existing designs, as well as suggesting modifications that might improve implant performance. This paper describes a case in which design considerations, rather than mechanical or material failure, appeared to be a major contributing factor.Sixteen months after insertion of a Howmedica Kinematic Rotating Hinge knee, the patient complained of barometric pain in the knee. Roentgenograms at that time showed the metallic axle component to be protruding laterally. Upon retrieval the polyethylene bumper-lock component exhibited deep scalloping on its surface, which unlocked the axle and allowed it to slide out.

Hemarthroses and warfarin: joint destruction with anticoagulation.

A 56 year old man was seen because of recurrent right shoulder hemarthroses and a superior vena caval syndrome. Intermittent symptoms had occurred for six years and resulted in marked destructive changes in the right shoulder. Arthroscopy added pathological evidence of this unusual mechanism of arthropathy. Patients on anticoagulants deserve close attention to symptoms of occult bleeding.