Darin Friess

Incidence and demography of femur fractures with and without atypical features.

The case definition, community incidence, and characteristics of atypical femoral shaft fractures (FSFs) are poorly understood. This retrospective study utilized electronic medical records and radiograph review among women ≥50 years of age and men ≥65 years of age from January 1996 to June 2009 at Kaiser Permanente Northwest to describe the incidence rates and characteristics of subgroups of femur fractures. Fractures were categorized based on the American Society for Bone and Mineral Research (ASBMR) as atypical fracture major features (AFMs) (low force, shaft location, transverse or short oblique, noncomminuted) and AFMs with additional minor radiograph features (AFMms) (beaking, cortical thickening, or stress fracture). There were 5034 fractures in the study. The incidence rates of FSFs (without atypical features) and AFMs appeared flat (cumulative incidence: 18.2 per 100,000 person‐years, 95% CI = 16.0–20.7; 5.9 per 100,000 person‐years, 95% CI = 4.6–7.4; respectively) with 1,271,575 person‐years observed. The proportion of AFMs that were AFMms increased over time. Thirty percent of AFMs had any dispensing of a bisphosphonate prior to the fracture, compared to 15.8% of the non‐atypical FSFs. Years of oral glucocorticosteroid dispensing appeared highest in AFM and AFMm fractures. Those with AFMs only were older and had a lower frequency of bisphosphonate dispensing compared to those with AFMms. We conclude that rates of FSFs, with and without atypia, were low and stable over 13.5 years. Patients with only AFMs appear to be different from those with AFMms; it may be that only the latter group is atypical. There appear to be multiple associated risk factors for AFMm fractures.

Augmentation of rabbit posterolateral spondylodesis using a novel demineralized bone matrix-hyaluronan putty

Study Design. Posterolateral spinal fusion with allogeneic demineralized bone graft–hyaluronan putty in addition to autogenous iliac crest bone graft in a rabbit model. Objectives. To determine the potential efficacy of demineralized bone graft–hyaluronan putty as a bone graft enhancer. Summary of Background Data. Autograft bone is the material of choice for posterolateral lumbar intertransverse process fusion. Bone graft alternatives such as demineralized bone matrices that can be used as graft extenders, enhancers, or substitutes continue to be developed. Methods. One hundred New Zealand white rabbits underwent bilateral posterolateral spinal fusion with autogenous iliac crest bone graft or bone graft with allogeneic rabbit demineralized bone graft–hyaluronan putty. The rabbits were killed 9 weeks later, and the lumbar spines were removed. Manual manipulation and fine detail radiography were used to assess spinal fusion, and computed tomographic images were used to quantify the volume of the fusion mass. Results. In comparison with autograft bone alone, the fusion rates were greater when demineralized bone graft–hyaluronan putty was used as an adjunct to autogenous bone. Furthermore, the radiographic fusion rate was greater when demineralized bone graft–hyaluronan putty was used in a 2:1 ratio to autograft bone in comparison with a 1:1 ratio (P = 0.001). The addition of demineralized bone graft–hyaluronan putty to autograft bone was found to increase mineralized bone volume in a ratio-dependent manner (P < 0.05). Conclusions. Allogeneic demineralized bone matrix–hyaluronan putty enhances rabbit posterolateral spine fusion when used as an adjunct to autogenous bone graft. This new formulation of demineralized bone matrix may facilitate greater bone formation and successful fusion.

Accuracy and interobserver agreement for determinations of rabbit posterolateral spinal fusion

Study Design. The accuracy and interobserver agreement of fine detail radiography and computed tomography (CT) determination of spinal fusion were evaluated in an established animal spine fusion model. Objective. To determine the accuracy and interobserver agreement of radiographic determinations of spinal fusion in rabbit posterolateral spine fusion. Summary of Background Data. The rabbit posterolateral intertransverse process spine fusion model is an established animal model for evaluating bone graft alternatives for spinal fusion. However, little is known regarding the accuracy and interobserver agreement of radiographic determinations of spondylodesis in this model. Methods. Forty-two New Zealand White rabbits underwent posterolateral spinal fusion. The animals were killed at 9 weeks and the lumbar spine harvested. Manual manipulation, fine detail radiography, and CT images were used to assess spinal fusion. Results. Using manual palpation testing as the standard by which to assess fusion, there was high sensitivity and negative predictive value for both radiographic methods. Positive predictive value, however, was poor (26% fine detail radiography, 61% CT scan). CT correlated better with manual palpation testing when compared with fine detail radiographs. There was substantial interobserver agreement of successful fusion using CT scan imaging (kappa = 0.63) and moderate interobserver agreement radiographs (kappa = 0.52). Conclusions. Both radiographic techniques used in the study recorded high sensitivity and negative predictive value. However, positive predictive value was poor, especially with fine detail radiographs. Nevertheless, CT with reformatted images did appear to be superior to fine detail radiographs in accurately identifying nonunions in this animal model.

Fracture of the proximal humerus with injury to the axillary artery in a boy aged 13 years

Fractures of the proximal humerus with concomitant vascular injury are rare in children. We describe the presentation, diagnosis, and treatment of a fracture of the proximal humerus in association with an axillary artery injury in a child.

Salvage Hip Arthroplasty After Failed Fixation of Proximal Femur Fractures

We reviewed 46 patients who underwent salvage hip arthroplasty (SHA) for revision of failed cannulated screws (CS), sliding hip screws (SHS), or intramedullary nails (IMN). The primary objective was to determine differences in operative difficulty. SHA after failed femoral neck fixation was associated with lower intra-operative demands than after failed peri-trochanteric fractures. Similarly, analysis by the index implant found that conversion arthroplasty after failed CSs was associated with lower intra-operative morbidity than failed SHSs or IMNs; differences between SHS and IMN were not as clear. Importantly, intra-operative data in cases of failed SHSs were similar regardless of the original fracture type, showing the device played a larger role than the fracture pattern. Complications and revision surgery rates were similar regardless of fracture type or fixation device. Our results suggest that operative demands and subsequent patient morbidity are more dependent on the index device than the fracture pattern during SHA.

Locking Plate Fixation for Proximal Humerus Fractures : A Comparison With Other Fixation Techniques

Various traditional surgical treatment methods for displaced proximal humerus fractures were compared with locking plates. Ninety-eight patients were reviewed and functional outcomes were obtained. After a mean 45-month follow-up, trends were noted toward better fracture reduction with locking plates and greater range of motion (ROM) with percutaneous pinning. Complications occurred in 22 patients, unrelated to treatment type. Method of fixation did not correlate with outcome scores, but functional ROM was associated with better American Shoulder and Elbow Surgeons (ASES) scores. Locking plates are comparable to traditional fixation methods. Functional ROM is associated with better outcome scores.

Healing Time and Complications in Operatively Treated Atypical Femur Fractures Associated With Bisphosphonate Use: A Multicenter Retrospective Cohort

Objectives: The purpose of this study was to characterize demographics, healing time, and complications of a large series of operatively treated atypical femur fractures. Design: Retrospective multicenter review. Setting: Seventeen academic medical centers. Patients: Bisphosphonate-related fractures as defined by American Society of Bone and Mineral Research. Fractures had to be followed for at least 6 months or to union or revision. Intervention: Operative treatment of bisphosphonate-related fracture. Main Outcome Measurements: Union time and complications of treatment, as well as information about the contralateral limb. Results: There were 179 patients, average age 72, average body mass index 27.2. Average follow-up was 17 months. Twenty-one percent had a previous history of fragility fracture; 34% had prodromal pain. Most (88%) lived independently before injury. Thirty-one percent had radiographic changes suggesting stress reaction. Surgical fixation was with cephalomedullary nail (51%), IM nail (48%), or plate (1%). Complications included death (4), PE (3), and wound infection (6). Twenty (12%) patients underwent revision at an average of 11 months. Excluding revisions, average union time was 5.2 months. For revisions, union occurred at an average of 10.2 months after intervention. No association was identified between discontinuation of bisphosphonates and union time (P = 0.5) or need for revision (P = 0.7). Twenty-one percent sustained contralateral femur fractures; 32% of these had pain and 59% had stress reaction before contralateral fracture. Conclusions: In this series, surgery had a 12% failure rate and delayed average time to union. Twenty-one percent developed contralateral femur fractures within 2 years, underscoring the need to evaluate the contralateral extremity. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Are distal femoral traction pins intra-articular? A cadaveric study

Objectives: To examine the frequency of intra-articular placement of distal femoral traction pins and their proximity to the superficial femoral artery (SFA). Methods: Wires were placed in the distal femurs of 28 cadaveric knees at the adductor tubercle (ADT), the superior pole of the patella (SPP), and 2 cm proximal to SPP (SPP+2). A lateral fluoroscopic image was obtained after injection of radiopaque contrast to assess for joint penetration. Dissection was performed to confirm or refute fluoroscopic findings. The distance from each wire to the SFA was measured. Results: The percentage of intra-articular placement was higher (29%) at the ADT than the SPP+2 (0%) level. The mean (SD) distances from the ADT, SPP, and SPP+2 to the SFA were 7.4 (±1.8) cm, 5.7 (±1.7) cm, and 3.8 (±1.7) cm, respectively (P < 0.0001). None of the wires penetrated the femoral artery. The proportion of wires judged to be intra-articular was not statistically different whether judged by fluoroscopy or anatomic dissection (exact P = 1.0). Conclusions: Wires placed at the level of the ADT are at risk for capsular penetration. Risk of major vascular injury with transmedullary placement at all levels seems to be minimal. The optimum position for distal femoral pins remains unknown, but aiming >0.7 cm proximal to the ADT may lower the risk of intra-articular placement. No difference was detected between fluoroscopic arthrography and gross dissection.

Alendronate influences bone volume in rabbit posterolateral spine fusion

Abstract Purpose of study: Bisphosphonate suppression of bone resorption is a documented phenomenon. The mechanism in which bisphosphonates inhibit osteoclastic resorption is being actively investigated. Bisphosphonates like alendronate have been shown to increase bone density and decrease fracture risk in both men and women. Recent studies have indicated that Alendronate may modulate osteoblastic activity as well. The purpose of this study is to investigate the effects of alendronate on spine fusion in an established rabbit posterolateral intertransverse fusion model. Methods used: Posterolateral spine fusion was performed in 45 skeletally mature New Zealand White male rabbits divided into three equal groups. Spondylodesis was attempted between the L5 and L6 lumbar vertebra with 1.4 gm of graft placed between the L5 and L6 transverse processes bilaterally in all rabbits. The study period was 9 weeks. The three experimental groups are described in Table 1. The equivalent oral dose is approximately 10 to 20 mg/kg/day in the high-dose group of rabbits and 1 to 2 mg/kg/day in the low-dose group. The volume of the fusion mass was determined from axial computed tomography scan images (1-mm section cuts). Fusion was assessed by evaluation of fine detail anteroposterior radiography and also by a manual palpation test. of findings: Attrition of five rabbits (two infections, three expired). After 9 weeks of alendronate administration, the mean difference in bone volume was significantly lower in the control group compared with either the high- or low-dose alendronate-treated rabbits (Fig. 1; p Relationship between findings and existing knowledge: Alendronate was associated with a significant increase in the volume of fusion mass. The results of this study suggest that alendronate not only inhibits bone resorption but also affects the bone formation and remodeling process of spinal fusion. This effect on spinal fusion may be detrimental at high doses of alendronate. The inhibitory effect of bisphosphonates on osteoclast-mediated bone resorption is well accepted. However, the direct or indirect effect of bisphosphonates on osteoblast-mediated bone formation and mineralization is still unclear. Both of these reactions play an integral role in the process of spine fusion. Further studies need to evaluate whether bisphosphonates have a direct effect on osteoblasts and bone formation or an indirect effect through coupled inhibition of bone resorption. To date, no study is available of the effects of alendronate on spine fusion. Overall significance of findings: The results of this study indicate a significant advantage to the systemic use of low-dose alendronate in enhancing rabbit posterolateral spine fusion volume. Disclosures: Device or drug: Alendronate. Status: approved. Conflict of interest: No conflicts.

Evaluating atypical features of femur fractures: How change in radiological criteria influenced incidence and demography of atypical femur fractures in a community setting†

Identification of atypical femoral fractures (AFFs) can be challenging. To assist in the radiological assessment, an American Society for Bone and Mineral Research (ASBMR) Task Force developed a case definition for AFFs in 2010, revising it in 2013. How the revised definition performs in a community setting compared with the 2010 definition is unknown. We applied the 2013 criteria to 372 femoral fractures that occurred between January 1, 1996, and June 30, 2009, employing two independent expert physician reviewers. We used radiographs that had been categorized in a previous study on the incidence of atypical fractures using 2010 ASMBR criteria (BEAK1). In this follow‐up study (BEAK2), the same reviewers reviewed all previously identified femoral shaft fractures (FSFs) (n = 197) and distal femur fractures (n = 131) plus a 15% random sample of intertrochanteric fractures (n = 49). After initial review, agreement between the two reviewers ranged from 63% to 100% for specific features, and 84% of radiographs received the same overall classification. Fewer fractures met the 2013 compared with 2010 ASMBR case definition of AFFs (37 per 2013 criteria versus 74 per 2010 criteria). Forty‐three radiographs (58%) categorized as AFFs according to 2010 criteria were no longer AFFs when 2013 criteria were applied, and an additional 12 non‐atypical FSFs according to 2010 criteria were reclassified as AFFs according to 2013 criteria. The major cause of AFF reclassification was the change in the definition of transverse configuration. The modification of the comminution, non‐traumatic, and periosteal/endosteal thickness criteria resulted in the reclassification of non‐atypical FSFs to AFFs. Incidence rate of AFFs according to 2013 ASBMR criteria was lower overall during the 13 years of observation than when the 2010 ASBMR criteria were applied, although we saw a slight increase starting in 2000. As in BEAK1, we found that those with AFFs were younger, more often female, and had a higher exposure rate to bisphosphonates than those with non‐atypical FSFs. As we continue to unravel the demographics of those who suffer from AFFs, our study adds information about how the change in criteria influences epidemiological work.