Materials and Methods: Forty eight hips with the conversion of bipolar HA to THA were followed up for an average 6.2 years (range 2.0-11.5 years). Twenty one hips had conversion surgery to THA using metal-on-metal articulation (28 or 32 mm head). Nine hips used ceramic-on-ceramic (28-40 mm) and eighteen hips used large head metal-on-metal bearing (>40 mm). Outcome was evaluated using Harris Hip Score (HHS) and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) score. The radiographs were analyzed for evidence of osteolysis and/or loosening. The complications were evaluated, especially dislocation with different femoral head diameter.

Results: Average HHS significantly improved from 42 preoperatively to 86 postoperatively and the average WOMAC score also significantly improved from 47 to 22 postoperatively. Radiological evaluation showed all the femoral components were stable. There was one acetabular component loosening, which required revision 9 years after conversion to THA. One dislocation and one recurrent dislocation were recorded in isolated acetabular revision hip; whereas one dislocation, one recurrent dislocation, and one trochanteric nonunion occurred in the hips with revision of both components. All dislocations occurred in hips with a femoral head size of 28 mm (P = 0.052). The cup and femoral head interval length was the most significant factor contributing to dislocation (P = 0.013).

METHODS: The study design was a prospective cross-sectional study. The participants involved injured motorcyclists who were admitted in five selected hospitals in Klang Valley, Malaysia. Participants who sustained head injury were selected as the cases while those with injury below the neck (IBN) were selected as the controls. Questionnaire comprising motorcyclist, vehicle, helmet and crash factors was examined. Diagnoses of injuries were obtained from the participants' medical records.

RESULTS: The total subjects with head injuries were 404 while those with IBN were 235. Majority of the cases (76.2%) and controls (80.4%) wore the half-head and open-face helmets, followed by the tropical helmets (5.4% and 6.0% of the cases and controls, respectively). Full-face helmets were used by 1.2% of the cases and 4.7% of the controls. 5.7% of the cases and 6.0% of the controls did not wear a helmet. 32.7% of the cases and 77.4% of the controls had their helmets fixed. Motorcyclists with ejected helmets were five times as likely to sustain head injury [adjusted odds ratio, AOR 5.73 (95% CI 3.38-9.73)] and four times as likely to sustain severe head injury [AOR of 4.83 (95% CI 2.76-8.45)]. The half head and open face helmets had AOR of 0.24 (95% CI 0.10-0.56) for severe head injury when compared to motorcyclists who did not wear a helmet.