RESUMO
OBJECTIVE: To examine the results of a treatment algorithm incorporating an EUA performed intraoperatively after fixation of the femoral head through a Smith Petersen approach to determine need for posterior wall or capsule repair. METHODS: Design: Retrospective review. SETTING: Two Level 1 trauma centers. PATIENT SELECTION CRITERIA: All acute, traumatic femoral head fractures from posterior hip dislocations treated at participating centers over a 5-year period from 2017-2022. Injuries were classified according to the Pipkin system. OUTCOME MEASURES AND COMPARISONS: The primary outcome was the result of intraoperative EUA performed after femoral head fixation to determine the need for Kocher-Langenbeck exposure for posterior wall and/or capsule fixation. The secondary outcomes included rates of avascular necrosis, heterotopic bone formation, late instability, and conversion to total hip arthroplasty. RESULTS: Studied were 63 males and 22 females with mean age 32.5 (range 18-71). 79 of 85 (92.9%) patients had a stable EUA after fixation of the femoral head through a Smith-Petersen approach. Six (6/85, 7.1%) underwent an additional Kocher-Langenbeck approach for posterior wall or capsule fixation. This included 1 Pipkin I, 1 Pipkin II, and 4 Pipkin IV injuries. Of the Pipkin IV injuries, 51/55 (92.7%) had stable EUA and did not require fixation of their posterior wall. This included 7 patients with wall involvement >20%. Five patients were excluded because of planned fixation of their posterior wall based on preoperative imaging. Of patients with at least 6 months follow up, 16 of 65 (26.4%) developed radiographic evidence of AVN and 21 of 65 (32.3%) evidence of heterotopic bone formation. Seven out of 65 (10.8%) were converted to total hip arthroplasty over the study period. When comparing patients with a single exposure with those with additional KL exposure, they did not vary in their rate of AVN (27.1% vs. 0.0%, P=0.3228), HO formation (30.5% vs. 50.0%, P=0.3788), or conversion to total hip arthroplasty (10.2% vs. 16.7%, P=0.510). CONCLUSIONS: This study found residual posterior hip instability after femoral head fixation in patients with and without posterior wall fractures after posterior dislocations. The results of this study support use of an EUA after femoral head fixation to identify residual posterior hip instability in all femoral head fractures from posterior hip dislocations, regardless of Pipkin type. Use of the Smith-Petersen exposure remains a viable surgical option and may be improved with incorporation of an EUA after femoral head fixation. For Pipkin IV injuries with posterior wall fractures with indeterminate stability, an EUA accurately identifies residual instability. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
RESUMO
Whether hybridization generates or erodes species diversity has long been debated, but to date most studies have been conducted at small taxonomic scales. Salamanders (order Caudata) represent a taxonomic order in which hybridization plays a prevalent ecological and evolutionary role. We employed a recently developed model of trait-dependent diversification to test the hypothesis that hybridization impacts the diversification dynamics of species that are currently hybridizing. We find strong evidence supporting this hypothesis, showing that hybridizing salamander lineages have significantly greater net-diversification rates than non-hybridizing lineages. This pattern is driven by concurrently increased speciation rates and decreased extinction rates in hybridizing lineages. Our results support the hypothesis that hybridization can act as a generative force in macroevolutionary diversification.