Contact mechanics of normal tarsometatarsal joints.

BACKGROUND: The current treatment of tarsometatarsal joint injuries is associated with suboptimal long-term results. The objective of the present study was to measure the contact mechanics of the tarsometatarsal joints in normal adult cadaveric feet in order to develop a foundation for more effective treatment. METHODS: Six fresh cadaveric lower legs and feet were subjected to four different axial compressive loads (0.5, 1.0, 1.5, and 2.0 times body weight) at each of five different positions. For each position, load, and tarsometatarsal joint, the contact pressures and areas were measured with use of pressure-sensitive film. Contact forces were calculated from the ratio of pressure to area. Contact pressure, area, and force were analyzed as a function of load, the specific tarsometatarsal joint, and foot position. RESULTS: The forces across these joints ranged from 2 to 541 N, but pressures ranged only from 0.5 to 5.7 MPa. In general, changes in load and foot position, in both the sagittal and the frontal plane, were associated with changes (p<0.05) in tarsometatarsal joint contact areas and forces. In contrast, the contact pressures across these joints varied minimally with changes in load and foot position. CONCLUSIONS: These data suggest that the tarsometatarsal joints are designed to regulate pressure in each joint by means of two mechanisms: (1) at small loads, an intrajoint mechanism regulates tarsometatarsal joint pressure by increasing contact area within the joint in response to increasing force, and (2) at larger loads, an interjoint mechanism engages to regulate tarsometatarsal joint pressure by redirecting force to other tarsometatarsal joints. CLINICAL RELEVANCE: The data provide both absolute (normal contact forces, areas, and pressures) and relative (intrajoint and interjoint regulating mechanisms) performance (functional) criteria for the development of new treatments for diseased or traumatized tarsometatarsal joints.

Evaluation of students' learning in an interdisciplinary medicine--surgery clerkship.

PURPOSE: To evaluate the impact of an interdisciplinary medicine-surgery clerkship (created to foster generalist education) on students' performances on National Board of Medical Examiners' (NBME) subject examinations. METHOD: Test data for the 226 students who participated in the 16-week combined clerkship and for the 265 students who had completed the traditional clerkships (12 weeks of medicine, 12 weeks of surgery) were compiled and analyzed using t-tests for independent samples. RESULTS: Mean scores on the NBME subject examination in medicine increased significantly after the combined medicine-surgery clerkship (from 433 to 455, p < or = 0.5). Mean scores on the NBME subject examination in surgery were similar to those achieved in the traditional clerkship years. CONCLUSION: Since the medicine and surgery clerkships were combined into a single, interdisciplinary clerkship, students' scores have increased on the medicine NBME subject examination and have remained relatively unchanged on the surgery NBME subject examination, despite a substantial reduction in students' clinical experience in the combined clerkship from the traditional clerkships (16 vs 24 weeks).

The effectiveness of the structured clinical instruction module.

BACKGROUND: The Structured Clinical Instruction Module (SCIM) provides students with a structured educational experience related to clinical skills on a single clinical topic. This study examined the effect of the SCIM on students' performances on breast stations in an objective structured clinical examination (OSCE). METHODS: Three student groups each experienced a different type of instruction about breast care and treatment (condition A = lecture; condition B = nine-station SCIM, lecture, and manual; and condition C = five-station SCIM). All students subsequently participated in a surgery OSCE that included standardized patient stations on taking a breast history and performing breast examinations. RESULTS: One-way analysis of variance (ANOVA) tests consistently found that the mean scores of students in conditions B and C were significantly (P < 0.05) higher than those of students in condition A. CONCLUSIONS: These results suggest that the SCIM is an effective patient-based standardized instructional program that enhances the instruction of clinical skills to students.

Isolated dislocation of the middle cuneiform in a farmer: a case report and review of the literature.

Isolated dislocations of the middle cuneiform are uncommon. There have been four reported previously. Significant force is required to produce these injuries, and they can have serious neurovascular consequences. In this case report and review of the literature, we present an isolated middle cuneiform dislocation in a 69-year-old farmer with impending skin and soft tissue loss over the dislocated bone.

Orthopaedic procedures and prognosis in hemophilic patients who are seropositive for human immunodeficiency virus.

Thirty patients who had hemophilia and were seropositive for the human immunodeficiency virus were evaluated. The preoperative CD4 lymphocyte count was decreased to an average of 336 x 10(9) per liter (range, 27 to 708 x 10(9) per liter). After twenty-six orthopaedic operations in patients who had no previous bacterial infection, a nosocomial infection (cellulitis in the forearm, at the site of an intravenous catheter) developed in only one patient, but five patients had an abnormal postoperative fever that was not accompanied by the expected increase in the white blood-cell count. The preoperative CD4 lymphocyte count was significantly reduced in the patients who had an abnormal elevation in body temperature (p less than 0.004). The functional result or outcome after operation was similar to that in hemophilic patients treated before 1982. Subsequent progression of infection with the human immunodeficiency virus, as determined by the CD4 lymphocyte count and the Walter Reed classification system, occurred in most patients. Acquired immunodeficiency syndrome was diagnosed in six patients. A more rapid progression to acquired immunodeficiency syndrome was seen in the patients who had a lower CD4 lymphocyte count preoperatively. Preoperative evaluation of the CD4 lymphocyte count and the response to intradermal skin-test antigens in patients who are at risk for infection postoperatively provides additional information concerning immunological competence. With these data, the possible risk of infection in patients who are seropositive for the human immunodeficiency virus can be estimated more accurately.

Surgical management of hemophilic arthropathy.

We reviewed the preoperative, intraoperative, and postoperative care of hemophilic patients, our experience with specific surgical procedures, and provided a cost-benefit analysis of joint replacement and synovectomy. The advent of factor VIII concentrates to control bleeding has enabled us to offer surgical options to hemophiliacs similar to those offered to patients with normal coagulation mechanisms. The appearance of the AIDS virus, however, has further complicated the care of hemophiliacs with severe arthropathy.