Does Screw Location Affect the Risk of Subtrochanteric Femur Fracture After Femoral Neck Fixation? A Biomechanical Study.

BACKGROUND: Case reports suggest that there is an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws when the distal-most screw is placed distal to the lesser trochanter. However, to our knowledge, there are no biomechanical data supporting this observation. QUESTIONS/PURPOSES: (1) Is there an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws in normal density and osteoporotic Sawbones when the distal-most screw is started distal to the lesser trochanter? (2) Does the screw starting point position after femoral neck fixation with cannulated screws affect load to failure when normal density and osteoporotic Sawbones are loaded through their mechanical axis? METHODS: Normal density and osteoporotic Sawbones femora were instrumented with three cannulated screws in a triangular apex distal configuration with the distal-most screw starting either proximal to, at, or distal to the level of the lesser trochanter. Specimens were loaded along the mechanical axis to failure. The fracture location and ultimate load to failure were compared between groups. RESULTS: The screw start point distal to the lesser trochanter resulted in a greater proportion of subtrochanteric femur fractures compared with screw start points at or proximal to the lesser trochanter in the subset of osteoporotic specimens (three of 10 specimens versus 0 of 20 specimens; p = 0.030). No subtrochanteric femur fractures were observed in the normal density specimens. Load to failure was lower when the distal-most screw was started distal to the lesser trochanter than when it was started at or proximal to the lesser trochanter (normal density subset 13,502 ± 1980 N versus 14,675 ±1528 N; osteoporotic subset 8946 ± 1509 N versus 10,026 ± 1256 N; linear regression coefficient 1127 N [95% CI 298 to 1956 N]; adjusted r = 0.71; p = 0.009). CONCLUSIONS: A screw start point distal to the lesser trochanter was associated with subtrochanteric femur fractures in the osteoporotic subset. Additionally, there was decreased load to failure when the distal-most screw was started distal to the lesser trochanter. CLINICAL RELEVANCE: These data suggest that avoiding a screw start point distal to the level of the lesser trochanter in femoral neck fracture fixation may decrease the risk of catastrophic subtrochanteric femur fractures, especially in patients with osteoporosis. However, it should be noted that a more overall varus screw alignment could theoretically compromise the ability to achieve compression across the fracture, with attendant implications with regard to fracture union in the acute setting.

Posterolateral clamp placement on the pelvic brim provides optimal reduction of transtectal acetabular fractures fixed through the anterior intrapelvic approach.

PURPOSE: To determine the optimal position of reduction clamps applied to reduce transtectal transverse acetabular fractures approached through the anterior intrapelvic route. METHODS: Transtectal transverse fractures were created in sawbone hemipelvis models. Fractures were reduced and held with a large pointed reduction clamp with one tine centered on the quadrilateral plate and the other placed in one of nine various positions on the pelvic brim accessible from the anterior intrapelvic (AIP) approach. Reduction was assessed by measuring maximum gapping and step-off at the joint surface. RESULTS: The posterolateral pelvic brim clamp position provided the most accurate reduction with the smallest articular fracture gap (mean 1.09 ± 1.05 mm) and step-off (mean 0.87 ± 1.35 mm). This clamp position, compared with the other positions as a whole, also yielded the highest proportion of perfect reductions (0 mm maximum displacement) for both step-off (83% vs 34%; RR 2.4, 95% CI 1.7-3.2) and gap (88% vs 49%; RR 1.8, 95% CI 1.4 to 2.2). CONCLUSIONS: When clamping transtectal fractures through the AIP approach, positioning the clamp posterolaterally on the pelvic brim appears to provide the best reduction in this fracture model.

Quality and Variability of Online Available Physical Therapy Protocols From Academic Orthopaedic Surgery Programs for Anterior Cruciate Ligament Reconstruction.

PURPOSE: To assess the quality and variability found across anterior cruciate ligament (ACL) rehabilitation protocols published online by academic orthopaedic programs. METHODS: Web-based ACL physical therapy protocols from United States academic orthopaedic programs available online were included for review. Main exclusion criteria included concomitant meniscus repair, protocols aimed at pediatric patients, and failure to provide time points for the commencement or recommended completion of any protocol components. A comprehensive, custom scoring rubric was created that was used to assess each protocol for the presence or absence of various rehabilitation components, as well as when those activities were allowed to be initiated in each protocol. RESULTS: Forty-two protocols were included for review from 155 U.S. academic orthopaedic programs. Only 13 protocols (31%) recommended a prehabilitation program. Five protocols (12%) recommended continuous passive motion postoperatively. Eleven protocols (26%) recommended routine partial or non-weight bearing immediately postoperatively. Ten protocols (24%) mentioned utilization of a secondary/functional brace. There was considerable variation in range of desired full-weight-bearing initiation (9 weeks), as well as in the types of strength and proprioception exercises specifically recommended. Only 8 different protocols (19%) recommended return to sport after achieving certain strength and activity criteria. CONCLUSIONS: Many ACL rehabilitation protocols recommend treatment modalities not supported by current reports. Moreover, high variability in the composition and time ranges of rehabilitation components may lead to confusion among patients and therapists. LEVEL OF EVIDENCE: Level II.

Early Characterization of Blast-related Heterotopic Ossification in a Rat Model.

BACKGROUND: Heterotopic ossification (HO) affects the majority of combat-related lower extremity wounds involving severe fracture and amputation. Defining the timing of early osteogenic-related genes may help identify candidate prophylactic agents and guide the timing of prophylactic therapy after blast and other combat-related extremity injuries. QUESTIONS/PURPOSES: Using a recently developed animal model of combat-related HO, we sought to determine (1) the timing of early chondrogenesis, cartilage formation, and radiographic ectopic bone development; and (2) the early cartilage and bone-related gene and protein patterns in traumatized soft tissue. METHODS: We used an established rat HO model consisting of blast exposure, controlled femur fracture, crush injury, and transfemoral amputation through the zone of injury. Postoperatively, rats were euthanized on Days 3 to 28. We assessed evidence of early ectopic bone formation by micro-CT and histology and performed proteomic and gene expression analysis. RESULTS: All rats showed radiographic evidence of HO within 28 days. Key chondrogenic (collagen type I alpha 1 [COL1α1], p = 0.016) and osteogenic-related genes (Runt-related transcription factor 2 [RUNX-2], p = 0.029; osteoclacin [OCN], p = 0.032; phosphate-regulating neutral endopeptidase, X-linked [PHEX], p = 0.0290, and POU domain class 5 transcription factor [POU5F], p = 0.016) and proteins (Noggin [NOG], p = 0.04, OCN, p = 0.02, RUNX- 2, p = 0.04, and substance P-1 [SP-1], p = 0.01) in the injured soft tissue, normalized to the contralateral limb and/or sham-treated naïve rats, increased on Days 3 to 14 postinjury. By 14 days, foci of hypertrophic chondrocytes, hyaline cartilage, and woven bone were present in the soft tissue surrounding the amputation site. CONCLUSIONS: We found that genes that regulate early chondrogenic and osteogenic signaling and bone development (COL1α1, RUNX-2, OCN, PHEX, and POU5F1) are induced early during the tissue reparative/healing phase in a rat model simulating a combat-related extremity injury. CLINICAL RELEVANCE: The ability to correlate molecular events with histologic and morphologic changes will assist researchers and clinicians to understand HO and hence formulate therapeutic interventions.