Chauffeur fractures or isolated radial styloid fractures (IRSF) are known to be associated with scapholunate ligament (SL) injuries. Diagnosis without arthroscopic confirmation is difficult in acute fractures. Acute management of this injury with early repair may prevent the need for more complex reconstructive procedures for chronic injuries. We investigated if all IRSF should be assessed arthroscopically for concomitant SL injuries. We performed a prospective cohort study on patients above the age of 16, presenting to the Gold Coast University Hospital with an IRSF, over 2 years. Plain radiographs and computerized tomography (CT) scans were performed. All patients had a diagnostic wrist arthroscopy performed in addition to an internal fixation of the IRSF. Patients were followed up for at least 3 months post operatively. SL repair was performed for all Geissler Grade 3/4 injuries. 10 consecutive patients were included in the study. There was no radiographic evidence of SL injuries in all patients. SL injuries were identified arthroscopically in 60% of patients and one third of these required surgical stabilisation. There were no post operative complications associated with wrist arthroscopy. We found that SL injuries occurred in 60% of IRSF and 20% of patients require surgical stabilisation. This finding is in line with the literature where SL injuries are reported in up to 40-80% of patients. Radiographic investigations were not reliable in predicting possible SL injuries in IRSF. However, no SL injuries were identified in undisplaced IRSF. In addition to identifying SL injuries, arthroscopy also aids in assisting and confirming the reduction of these intra-articular fractures. In conclusion, we should have a high index of suspicion of SL injury in IRSF. Arthroscopic assisted fixation should be considered in all displaced IRSF. This is a safe additional procedure which may prevent missed SL injuries and their potential sequelae.
Axial loading of the wrist results in carpal pronation, which loads the scapholunate ligament (SLL). ECRL and FCR are carpal supinators and ECU is a carpal pronator. In this study we aim to show differential activity in the ECRL and ECU as a protective mechanism for the SLL in simulated falls. Eight healthy volunteers were recruited for a simulated fall situation. Surface EMG was used to record muscle activity in the six major muscles that control wrist movement (FCU, FCR, ECRL, ECU, APL, ECRB) in the right forearm. The forearm skin was prepared in a standard fashion and the electrodes placed following an established protocol. Recordings were made using zero wire (Noraxon) surface EMG equipment. The data was exported and analysed using MyoResearch XP. Recordings were rectified and mean value, peak value, area under the curve and frequency were compared. Recordings were divided into five time periods from rest to post-impact. ECRL has the most predictable and consistent response to impact of the wrist on the ground. Immediately following impact there is inhibition of the extensors and no change in flexor activity. The next phase is characterised by a ‘spike’ in ECRL activity with a less marked increase in ECRB and minimal change in ECU activity. There is decrease activity in the flexors during the ECRL peak. The pre-peak period lasts between 5 to 10 ms. The ECRL peak period lasts between 20 to 30 ms. We have identified that ECRL is active post fall and this response takes less than 10 ms from the time of impact. The time response is in the order of a spinal proprioceptive reflex. We were unable to identify a stretch response in the flexors that could act to trigger the ECRL response.
