Biomechanical analysis of distal clavicle excision with acromioclavicular joint reconstruction.

BACKGROUND: Acromioclavicular (AC) joint separation is a common injury, usually affecting young adults. Controversy exists regarding whether to excise the distal clavicle when surgical intervention is required. PURPOSE: To evaluate the biomechanical strength of AC and coracoclavicular (CC) ligament reconstruction with and without concurrent distal clavicle excision. STUDY DESIGN: Controlled laboratory study. METHODS: Nine matched pairs of cadaver shoulders were used. All shoulders were tested with intact CC and AC ligaments, and the ligaments were sectioned. For 1 shoulder in each pair, a 7-mm distal clavicle excision was performed. The contralateral distal clavicle was left intact. Single-tunnel CC ligament reconstruction was performed, and excess graft length was extended and secured across the AC joint to reconstruct the superior AC joint ligaments in all specimens. Specimens were then potted and cyclically loaded for 500 cycles in the anterior-posterior and superior-inferior planes using an MTS Minibionix load frame to evaluate displacement across the AC joint. RESULTS: Regarding the clavicle-intact reconstructed versus the intact state, there was significantly greater AC joint translation in the reconstructed state in the anterior-posterior (20.2 ± 7.0 mm vs 6.0 ± 1.5 mm; P < .001) and superior-inferior directions (12.3 ± 3.3 mm vs 4.2 ± 1.2 mm; P < .001). In the clavicle-excised reconstructed versus the intact state, there was also significantly greater translation in the reconstructed state in the anterior-posterior (21.7 ± 5.1 mm vs 8.9 ± 4.3 mm; P < .001) and superior-inferior directions (12.3 ± 6.1 mm vs 5.8 ± 3.1 mm; P < .001). When the difference in translation between the reconstructed and intact groups in the clavicle-intact versus the clavicle-excised group was compared, no statistically significant difference was noted in anterior-posterior (14.2 ± 7.8 mm vs 12.8 ± 5.0 mm; P = .67) or superior-inferior translation (8.1 ± 2.9 mm vs 6.6 ± 3.9 mm; P = .39). CONCLUSION: Excision of the distal clavicle did not have a significant effect on anterior-posterior or superior-inferior motion at the AC joint following single-tunnel CC and AC ligament reconstruction. CLINICAL RELEVANCE: The study suggests that excision of the distal clavicle in this procedure is not associated with increased anterior-posterior or superior-inferior instability in this model.

Effect of environment and research participant characteristics on data quality.

The purpose of this study, a component of a randomized clinical trial, was to assess the influence of the emergency department environment and participant characteristics on the accuracy of self-reported health care utilization. Interviews of 612 seniors aged 65 to 93 were conducted in two emergency departments. The research assistant, upon completion of each interview, rated characteristics of the emergency department and compared participants' self-reports of emergency department use and hospitalization during the previous 4 weeks with data from hospital records: 3.6% overreported and 2.2% underreported visits to the emergency department. Regarding hospitalizations, 2.6% overreported and 1.2% underreported. Discrepancies were associated with male gender, cognitive deficits, and risk status. Inconsistencies were not related to any of the environmental variables. These findings suggest that seniors without cognitive decline report reliable data even in a potentially challenging environment.