RESUMO
Purpose: To determine whether there are changes in nerve conduction studies (NCS) of the median nerve after distal radius fracture (DRF) and to determine how operative fixation through a volar approach with a locking plate contributes to nerve conduction changes. We hypothesized that a considerable percentage of patients would have electrodiagnostic evidence of median neuropathy at the wrist after fracture, but fixation with a volar locked plate would not worsen the electrodiagnostic findings. Methods: This was a prospective cohort study of 14 neurologically asymptomatic patients who underwent surgical treatment of an isolated DRF using a volar plate. All patients underwent surgery within 2 weeks of injury. On the day of surgery and at the 6-week follow-up, patients were clinically examined, Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire was completed, and patients underwent NCS using a handheld device with the unaffected limb, which was used as a comparison. Preoperative and postoperative nerve function were compared with the unaffected limb as a baseline. Results: Patients without symptoms after DRF had a 28% incidence of prolonged latencies compared with reference values for the device used. Distal sensory latencies of the median nerve were 3.64 ± 0.32 ms in the unaffected arm, 3.76 ± 0.70 ms before surgery, and 3.81 ± 0.52 ms after surgery. Distal motor latencies of the median nerve were 3.91 ± 0.59, 3.60 ± 0.68, and 3.88 ± 0.36 ms in respective arms and time points. Quick-Disabilities of the Arm, Shoulder, and Hand scores improved from 77 before surgery to 46 at 6 weeks. Conclusions: Asymptomatic patients may satisfy nerve conduction criteria for median neuropathy at the wrist after DRF; however, open reduction and treatment with a volar locked plate has no significant effect on NCS findings. Type of study/level of evidence: Prognostic II.
RESUMO
BACKGROUND: Animal models are often used to assess interventions that might improve fat grafting outcomes; however, there is great variability in the models. The authors sought to determine the predictive value of the immunocompromised mouse model for fat grafting so that experiments could be standardized and optimized. METHODS: Human lipoaspirate injections at different volumes and time points were assessed in a nude mouse model and compared with control injections of nonviable fat. Volume retention and explant histologic score were compared. In a separate study, interanimal reproducibility was determined by implanting a highly consistent hydrogel and measuring variability in volume retention. RESULTS: Injection volume significantly affects adipose resorption kinetics at 6 and 12 weeks. Masson trichrome staining revealed that macrophages were unable to infiltrate large (1 ml) grafts, and oil cysts were not absorbed by 18 weeks, which interfered with interpretation of volume retention data. Nonviable tissue was resorbed when grafts were 0.3 ml, and quantification of graft histologic viability correlated well with graft retention at all study time points. Interanimal variability was measured to be 8.44 percent of the mean retention volume for small graft volumes. CONCLUSIONS: Human fat graft retention in the immunodeficient mouse correlates with graft viability in small, 0.3-ml-volume grafts. However, centralized oil cysts in nonviable 1.0-ml grafts were not resorbed by 18 weeks and thus volume measurements were confounded and not significantly different from viable samples. In addition, tissue injury scores increased in initially healthy fat grafts at 18 weeks, possibly because of a delayed immune reaction.