A knee model for arthrocentesis simulation.

OBJECTIVES: To produce a knee model for medical students and residents to practice knee aspiration and intra-articular injection. MATERIAL AND METHOD: The model was made of plastic, rubber and silicone that included the lower third of the femur, the upper third of the tibia and the patella. They were fixed on 2 plastic boxes in the anatomical position and the boxes were connected together with 2 small hinge joints. A rubber bag was made in the pattern of synovial space of the knee. Quadriceps, anterior muscles of the leg and patellar tendon were also presented. The model was covered with silicon sheet, representing the skin. Water was used to fill up the synovial bag to simulate joint aspiration via supero-lateral approach with the knee in extension. The model was appraised by 30 medical students, 26 orthopedic residents and 10 orthopedic staff in terms of size, anatomy, physical examination, feeling during aspiration, need of the model in education and commercial use. RESULTS: Most of the medical students, residents and staff (80-90%) were satisfied with the model and rated it as good to very good teaching media. However, the model should come out in different sizes and the synovial bag should be modified to improve the ballotment test. Mass production of the model should be done. CONCLUSION: The knee model is an acceptable teaching model for arthrocentesis simulation with affordable cost.

A comparison of lumbar microdiscectomy versus standard discectomy.

Forty patients with a diagnosis of simple herniated lumbar disc at L4-5 were reviewed group I comprised 20 patients treated with standard discectomy. Group II comprised 20 patients treated with microdiscectomy. Both groups had similar characteristics regarding age (average=35.9, 35.1 years), sex (M/F=10/10,11/9), side (R/L=11/9,9/11) and time period from beginning of their symptoms to the index operation (average=8.4,9.8 months). In group I, 81 percent of the patients had numbness over the L5 dermatome, while all in group II had the same symptom. In group I, 71.4 percent of the patients had weakness of extensor hallucis longus, while 75 percent had the same symptom in group II. Myelograms were performed on eight patients in group I and on nine patients in group II. Magnetic resonance images were performed on twelve patients in group I and on eleven patients in group II. The data were retrieved from the patients’ records and a comparison made through analyses of the unpaired T test. There was no statistical difference in operative time (average of 83.7 versus 81.6 minutes with p=0.72), or improvement of pain and daily activities at six weeks after the index operations. There were significant differences in length of incision (average 10.6 versus 3.3 cm.), intraoperative blood loss (average=180 versus 48 cc.), length of stay in the hospital after the operation (average=12.3 versus 4.2 days). A complication with a tear of the dura occurred in one patient in group II. One patient in each group developed recurrence of herniated disc at the same level which was resolved by conservative means. Microdiscectomy in selected patients is effective and give comparable results to the standard procedure with the advantages of a smaller incision, less blood loss and shorter length of hospital stay.