Fix or Replace? Patient Preferences for the Treatment of Geriatric Lower Extremity Fractures: A Discrete Choice Experiment

Introduction

When considering treatment options for geriatric patients with lower extremity fractures, little is known about which outcomes are prioritized by patients. This study aimed to determine the patient preferences for outcomes after a geriatric lower extremity fracture.

Materials and Methods

We administered a discrete choice experiment survey to 150 patients who were at least 60 years of age and treated for a lower extremity fracture at a Level I trauma center. The discrete choice experiment presented study participants with 8 sets of hypothetical outcome comparisons, including joint preservation (yes or no), risk of reoperation at 6 months and 24 months, postoperative weightbearing status, disposition, and function as measured by return to baseline walking distance. We estimated the relative importance of these potential outcomes using multinomial logit modeling.

Results

The strongest patient preference was for maintained function after treatment (59%, P < .001), followed by reoperation within 6 months (12%, P < .001). Although patients generally favored joint preservation, patients were willing to change their preference in favor of joint replacement if it increased function (walking distance) by 13% (SE, 66%). Reducing the short-term reoperation risk (12%, P < .001) was more important to patients than reducing long-term reoperation risk (4%, P = .33). Disposition and weightbearing status were lesser priorities to patients (9%, P < .001 and 7%, P < .001, respectively).

Discussion

After a lower extremity fracture, geriatric patients prioritized maintained walking function. Avoiding short-term reoperation was more important than avoiding long-term reoperation. Joint preservation through fracture fixation was the preferred treatment of geriatric patients unless arthroplasty or arthrodesis provides a meaningful functional benefit. Hospital disposition and postoperative weightbearing status were less important to patients than the other included outcomes.

Conclusions

Geriatric patients strongly prioritize function over other outcomes after a lower extremity fracture.

Can an Orthopedic Hip Fracture Simulator Advance Orthopedic Residents' Hip Fracture Fixation Skills to an Expert Level?

OBJECTIVE

This study was undertaken to evaluate hip fracture simulator training and orthopedic resident skill attainment. We hypothesized that after 6 training sessions, improvement in post-training scores in junior residents would exceed that of senior residents and that senior residents would attain expert level proficiency sooner.

DESIGN

Thirty orthopedic residents from a single institution completed 6 training sessions. Sessions included a pretest, 9 training modules, and post-test. An expert score was obtained from the average scores of 8 trauma fellows and attending orthopedic traumatologists. The primary outcome measure was overall score.

SETTING

A single academic institution.

PARTICIPANTS

Orthopedic residents (postgraduate years [PGYs] 1-5).

RESULTS

Twenty-six residents completed the study. The mean overall post-training score was 87% of the expert level. Factors associated with post-training score changes were additional training sessions (4.2% improvement [p < 0.01]), time between training sessions (0.3% decrease [p = 0.05]) and PGY5 class (12.1% improvement [p = 0.03]). Fifty-four percent of residents attained the expert overall score. Expert score attainment was not associated with an additional year of training or case log volume. Post-training scores plateaued for the PGY1s and showed linear improvement for the PGY5s.

CONCLUSIONS

Differences in trends between training levels suggest this simulator is a useful adjunct to a 5-year orthopedic residency training program.

Socioeconomic status is associated with greater hazard of post-discharge mortality than race, gender, and ballistic injury mechanism in a young, healthy, orthopedic trauma population

OBJECTIVES

To explore the utility of legacy demographic factors and ballistic injury mechanism relative to popular markers of socioeconomic status as prognostic indicators of 10-year mortality following hospital discharge in a young, healthy patient population with isolated orthopedic trauma injuries.

METHODS

A retrospective cohort study was performed to evaluate patients treated at an urban Level I trauma center from January 1, 2003, through December 31, 2016. Current Procedure Terminology (CPT) codes were used to identify upper and lower extremity fracture patients undergoing operative fixation. Exclusion criteria were selected to yield a patient population of isolated extremity trauma in young, otherwise healthy individuals between the ages of 18 and 65 years. Variables collected included injury mechanism, age, race, gender, behavior risk factors, Area Deprivation Index (ADI), and insurance status. The primary outcome was post-discharge mortality, occurring at any point during the study period.

RESULTS

We identified 2539 patients with operatively treated isolated extremity fractures. The lowest two quartiles of socioeconomic status (SES) were associated with higher hazard of mortality than the highest SES quartile in multivariable analysis (Quartile 3 HR: 2.2, 95% CI: 1.2-4.1, p = 0.01; Quartile 4 HR: 2.2, 95% CI: 1.1-4.3, p = 0.02). Not having private insurance was associated with higher mortality hazard in multivariable analysis (HR 2.0, 95% CI: 1.3-3.2, p = 0.002). The presence of any behavioral risk factor was associated with higher mortality hazard in univariable analysis (HR: 1.8, p < 0.05), but this difference did not reach statistical significance in multivariable analysis (HR: 1.4, 95%: 0.8-2.3, p = 0.20). Injury mechanism (ballistic versus blunt), gender, and race were not associated with increased hazard of mortality (p > 0.20).

CONCLUSION

Low SES is associated with a greater hazard of long-term mortality than ballistic injury mechanism, race, gender, and medically diagnosable behavioral risk factors in a young, healthy orthopedic trauma population with isolated extremity injury.

The Biomechanical Effects of Intramedullary Fixation to the Level of the Physeal Scar on Distal Tibia Fracture Stability

INTRODUCTION

The purpose of this study was to evaluate whether intramedullary nail contact with physeal scar improves construct mechanics when treating distal tibial shaft fractures.

METHODS

Axially unstable extra-articular distal tibia fractures were created in 30 fresh frozen cadaveric specimens (15 pairs, mean age 79 years). Specimens underwent intramedullary nailing to the level of the physeal scar locked with one or two interlocks or short of the physeal scar locked with two interlocks (reference group). Specimens were subjected to 800N of axial load for 25,000 cycles. Primary outcomes were stiffness before and after cyclic loading. Secondary outcomes were load to failure, load at 3 mm displacement, plastic deformation, and total deformation.

RESULTS

The physeal scar with one interlock cohort demonstrated 3.8% greater stiffness before cycling ( P = 0.75) and 1.7% greater stiffness after cycling ( P = 0.86) compared with the reference group. The physeal scar with two interlocks group exhibited 0.3% greater stiffness before cycling ( P = 0.98) and 8.4% greater stiffness after cycling ( P = 0.41) in relation to the reference group. No differences were identified regarding load to failure or load at 3 mm displacement. In specimens with two interlocks, those in contact with the physeal scar demonstrated significantly less plastic ( P = 0.02) and total ( P = 0.04) deformation.

CONCLUSIONS

Constructs ending at the physeal scar demonstrated stiffness and load to failure similar to those without physeal scar contact. Less plastic and total deformation was noted in two-interlock constructs with physeal scar contact, suggesting a possible protective effect provided by the physeal scar. These data argue that physeal scar contact may offer a small mechanical benefit in nailing distal tibia fractures, but clinical relevance remains unknown.

Using Discrete Choice Experiments to Quantify Patient Preferences

Discrete choice experiments are a robust technique for quantifying preferences. With this method, respondents are presented with a series of hypothetical comparisons described by attributes with varying levels. The aggregated choices from respondents can be used to infer the relative importance of the described attributes and acceptable trade-offs between attributes. The data generated from discrete choice experiments can aid surgeons in aligning patient values with treatment decisions and support the design of research that is responsive to patient preferences. This article summarizes the application of discrete choice experiments to orthopaedics. We share best practices for designing discrete choice experiments and options for reporting study results. Finally, we suggest opportunities for this method within our field.

Work Productivity Loss After Minimally Displaced Complete Lateral Compression Pelvis Fractures

OBJECTIVE

To quantify work impairment and economic losses due to lost employment, lost work time (absenteeism), and lost productivity while working (presenteeism) after a lateral compression pelvic ring fracture. Secondarily, productivity loss of patients treated with surgical fixation versus nonoperative management was compared.

METHODS

DESIGN

Secondary analysis of a prospective, multicenter trial.

SETTING

Two level I academic trauma centers.

PATIENT SELECTION CRITERIA

Adult patients with a lateral compression pelvic fracture (OTA/AO 61-B1/B2) with a complete posterior pelvic ring fracture and less than 10 mm of initial displacement. Excluded were patients who were not working or non-ambulatory before their pelvis fracture or who had a concomitant spinal cord injury.

OUTCOME MEASURES AND COMPARISONS

Work impairment, including hours lost to unemployment, absenteeism, and presenteeism, measured by Work Productivity and Activity Impairment assessments in the year after injury. Results after non-operative and operative treatment were compared.

RESULTS

Of the 64 included patients, forty-seven percent (30/64) were treated with surgical fixation, and 53% (30/64) with nonoperative management. 63% returned to work within 1 year of injury. Workers lost an average of 67% of a 2080-hour average work year, corresponding with $56,276 in lost economic productivity. Of the 1395 total hours lost, 87% was due to unemployment, 3% to absenteeism, and 10% to presenteeism. Surgical fixation was associated with 27% fewer lost hours (1155 vs. 1583, P = 0.005) and prevented $17,266 in average lost economic productivity per patient compared with nonoperative management.

CONCLUSIONS

Lateral compression pelvic fractures are associated with a substantial economic impact on patients and society. Surgical fixation reduces work impairment and the corresponding economic burden.

LEVEL OF EVIDENCE

Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Small-Fragment Plate Fixation of Humeral Shaft Fractures

Fixation of humeral shaft fractures is frequently performed with large-fragment (4.5 mm) plates to accommodate immediate weight bearing. Use of small-fragment (3.5 mm) plates as an alternative carries theoretical benefits. We examined nonunion rates and postoperative radial nerve palsy (RNP) rates in a retrospective cohort of patients undergoing open reduction and internal fixation of humeral shaft fractures with 3.5-mm or 4.5-mm plates. Two hundred thirty-six patients with 241 humeral shaft fractures were included. Small 3.5-mm plates were used in 83% of the patients, and large 4.5-mm plates were used in 17% of the patients. Fifty-three percent were made weight bearing as tolerated following surgical fixation. There was a 7% incidence of nonunion and a 10% incidence of RNP in the 3.5-mm plate group. There was a 7% incidence of nonunion and a 15% incidence of RNP in the 4.5-mm plate group. No statistically significant relationship was shown between nonunion or RNP and plate size (P=.74 and P=.39). No relationship was shown between nonunion and postoperative weight-bearing status (P=.45). Subgroup analysis according to plate size additionally showed no association of nonunion with postoperative weight bearing in both the 4.5-mm (P=.55) and the 3.5-mm (P=.25) cohorts. Small-fragment and large-fragment plating of humeral shaft fractures resulted in comparable union and RNP rates, regardless of postoperative weight-bearing status. Our findings suggest that 3.5-mm plate fixation of humeral shaft fractures is a safe alternative to 4.5-mm plate fixation. [Orthopedics. 2023;46(4):198-204.].

Can a Computer-based Force Feedback Hip Fracture Skills Simulator Improve Clinical Task Performance? A Cadaveric Validation Study

BACKGROUND

This cadaveric study seeks to determine whether skills acquired on the simulator translate to improved performance of the clinical task. We hypothesized that completion of simulator training modules would improve performance of percutaneous hip pinning.

METHODS

Eighteen right-handed medical students from two academic institutions were randomized: trained (n = 9) and untrained (n = 9). The trained group completed nine simulator-based modules of increasing difficulty, designed to teach techniques of placing wires in an inverted triangle construct in a valgus-impacted femoral neck fracture. The untrained group had a brief simulator introduction but did not complete the modules. Both groups received a hip fracture lecture, an explanation and pictorial reference of an inverted triangle construct, and instruction on using the wire driver. Participants then placed three 3.2 mm guidewires in cadaveric hips in an inverted triangle construct under fluoroscopy. Wire placement was evaluated with CT at 0.5 mm sections.

RESULTS

The trained group significantly outperformed the untrained group in most parameters (P ≤ 0.05).

CONCLUSIONS

The results suggest that a force feedback simulation platform with simulated fluoroscopic imaging using an established, increasingly difficult series of motor skills training modules has potential to improve clinical performance and might offer an important adjunct to traditional orthopaedic training.

Does iliosacral screw removal reduce postoperative pain in unstable pelvic fracture patients? A matched prospective cohort study

BACKGROUND

To compare pain and function in patients with unstable posterior pelvic fractures stabilized with posterior fixation who undergo iliosacral screw removal versus those who retain their iliosacral screws.

METHODS

A prospective observational cohort study identified 59 patients who reported pain at least 4 months after iliosacral screw fixation of an unstable posterior pelvic ring fracture from 2015-2019. The primary intervention was iliosacral screw removal versus a matched iliosacral screw retention control group. Patient-reported pain was measured with the 10-point Brief Pain Inventory, and patient-reported function was measured with the Majeed Pelvic Outcome Score. Both measured within 6 months of the intervention.

RESULTS

Before iliosacral screw removal, the mean pain was 4.7 (SD, 3.0) compared with 4.7 (SD, 3.0) in the matched control group. Following iliosacral screw removal, the average pain in the screw removal group was 3.7 (SD, 2.7) and 3.3 (SD, 2.5) in the matched control group. We found no evidence that iliosacral screw removal reduced pain in this population (mean difference, 0.2 points; 95% CI, -1.0 to 1.5; p = 0.71). In addition, the improvement in function after iliosacral screw removal was not statistically indistinguishable from zero (mean difference, 3.1 points; 95% CI, -4.6 to 10.9; p = 0.42).

CONCLUSIONS

The results suggest that iliosacral screw removal offers no significant pelvic pain or function benefit when compared with a matched control group. Surgeons should consider these data when managing patients with pelvic pain who are candidates for iliosacral screw removal.

Effect of Vitamin D3 Supplementation on Acute Fracture Healing: A Phase II Screening Randomized Double-Blind Controlled Trial

Nearly half of adult fracture patients are vitamin D deficient (serum 25-hydroxyvitamin D [25(OH)D] levels <20 ng/mL). Many surgeons advocate prescribing vitamin D supplements to improve fracture healing outcomes; however, data supporting the effectiveness of vitamin D₃ supplements to improve acute fracture healing are lacking. We tested the effectiveness of vitamin D₃ supplementation for improving tibia and femur fracture healing. We conducted a single-center, double-blinded phase II screening randomized controlled trial with a 12-month follow-up. Patients aged 18-50 years receiving an intramedullary nail for a tibia or femoral shaft fracture were randomized 1:1:1:1 to receive (i) 150,000 IU loading dose vitamin D₃ at injury and 6 weeks (n = 27); (ii) 4000 IU vitamin D₃ daily (n = 24); (iii) 600 IU vitamin D₃ daily (n = 24); or (iv) placebo (n = 27). Primary outcomes were clinical fracture healing (Function IndeX for Trauma [FIX-IT]) and radiographic fracture healing (Radiographic Union Score for Tibial fractures [RUST]) at 3 months. One hundred two patients with a mean age of 29 years (standard deviation 8) were randomized. The majority were male (69%), and 56% were vitamin D₃ deficient at baseline. Ninety-nine patients completed the 3-month follow-up. In our prespecified comparisons, no clinically important or statistically significant differences were detected in RUST or FIX-IT scores between groups when measured at 3 months and over 12 months. However, in a post hoc comparison, high doses of vitamin D₃ were associated with improved clinical fracture healing relative to placebo at 3 months (mean difference [MD] 0.90, 80% confidence interval [CI], 0.08 to 1.79; p = 0.16) and within 12 months (MD 0.89, 80% CI, 0.05 to 1.74; p = 0.18). The study was designed to identify potential evidence to support the effectiveness of vitamin D₃ supplementation in improving acute fracture healing. Vitamin D₃ supplementation, particularly high doses, might modestly improve acute tibia or femoral shaft fracture healing in healthy adults, but confirmatory studies are required. The Vita-Shock trial was awarded the Orthopaedic Trauma Association's (OTA) Bovill Award in 2020. This award is presented annually to the authors of the most outstanding OTA Annual Meeting scientific paper. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Fixed angle device comparison in young femoral neck fractures: Dynamic hip screw vs dynamic helical hip system

INTRODUCTION

Femoral neck fractures in the young patient present a unique challenge. Most surgeons managing these injuries prefer a fixed angle implant, however these devices are fraught with problems. A dynamic hip screw (DHS) is one such fixed angle device that risks malreduction through rotational torque during screw insertion. To avoid this risk some surgeons utilize a dynamic helical hip system (DHHS), however little is known about the complication profile of this device. We hypothesized that the complication rate between these two devices would be similar.

PATIENTS AND METHODS

All patients presenting to a single tertiary referral center with a femoral neck fracture were identified from a prospectively collected trauma database over an 11-year period. Patients were included if they were less than 60 years of age, treated with a DHS or DHHS, and had at least 6 months of follow-up. Demographic data, injury characteristics, and post-operative complications were obtained through chart review. Standard statistical comparisons were made between groups. A total of 77 patients met inclusion criteria.

RESULTS

Average age of patients was 38 years (range: 18-59) and 56 (73%) were male. The DHS was used in 37 (48%) patients and the DHHS was used in 40 (52%) patients. Demographic data including average age, gender, body mass index, and smoking status did not differ between the groups. There were 29 (39%) total complications of interest (femoral neck shortening >5 mm, non-union requiring osteotomy, conversion to THA, and osteonecrosis. There were 19 (51%) complications in the DHS group and 10 (25%) in the DHHS group (p = 0.01, risk difference 25%, 95% CI 7-43). Comparisons of the individual complications about the DHS and DHHS cohort did not reach statistical significance for non-union (8% vs 3%) or THA (16% vs 13%) (p = 0.33, p = 0.64, respectively) but a difference was detected in the rate of shortening (27% vs 10%; p = 0.05).

CONCLUSION

This study demonstrates a high risk of complication when managing young femoral neck fractures in line with prior literature. The major complication rate of non-union requiring osteotomy or fixation failure resulting in THA was no different between the two groups, but the rate of shortening was greater the DHS group. This data suggests the DHHS may be a suitable device to manage the young femoral neck fracture and without increased risk of complication.

Assessing Soft Tissue Perfusion Using Laser-Assisted Angiography in Tibial Plateau and Pilon Fractures: A Pilot Study

OBJECTIVES

To determine whether skin perfusion surrounding tibial plateau and pilon fractures is associated with the Tscherne classification for severity of soft tissue injury. The secondary aim was to determine if soft tissue perfusion improves from the time of injury to the time of definitive fracture fixation in fractures treated using a staged protocol.

DESIGN

Prospective cohort study.

SETTING

Academic trauma center.

PATIENTS

Eight pilon fracture patients and 19 tibial plateau fracture patients who underwent open reduction internal fixation.

MAIN OUTCOME MEASURES

Skin perfusion (fluorescence units) as measured by LA-ICGA.

RESULTS

Six patients were classified as Tscherne grade 0, 9 as grade 1, 10 as grade 2, and 2 as grade 3. Perfusion decreased by 14 fluorescence units (95% confidence interval, -21 to -6; P < 0.01) with each increase in Tscherne grade. Sixteen patients underwent staged fixation with an external fixator (mean time to definitive fixation 14.1 days). The mean perfusion increased significantly at the time of definitive fixation by a mean of 13.9 fluorescence units (95% confidence interval 4.8-22.9; P = 0.01).

CONCLUSIONS

LA-ICGA perfusion measures are associated with severity of soft tissue injury surrounding orthopaedic trauma fractures and appear to improve over time when fractures are stabilized in an external fixator. Further research is warranted to investigate whether objective perfusion measures are predictive of postoperative wound healing complications and whether this tool can be used to effectively guide timing of safe surgical fixation.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

A Prospective Clinical Trial Comparing Surgical Fixation Versus Nonoperative Management of Minimally Displaced Complete Lateral Compression Pelvis Fractures

OBJECTIVE

To compare the early pain and functional outcomes of operative fixation versus nonoperative management for minimally displaced complete lateral compression (LC; OTA/AO 61-B1/B2) pelvic fractures.

DESIGN

Prospective clinical trial.

SETTING

Two academic trauma centers.

PATIENTS

Forty-eight adult patients with LC pelvic ring injuries with <10 mm of displacement were treated nonoperatively and 47 with surgical fixation. Sixty percent of participants were randomized. Seventy-three percent of the fractures were displaced <5 mm, and 71% were LC-1 patterns.

INTERVENTION

Operative fixation versus nonoperative management.

MAIN OUTCOME MEASUREMENTS

The primary outcome was patient-reported pain using the 10-point Brief Pain Inventory. Functional outcome was measured using the Majeed pelvic score. Outcomes were analyzed using hierarchical Bayesian models to compare the average treatment effect from injury to 12 and 52 weeks postinjury. The probability of the mean treatment benefit exceeding a clinically important difference was determined.

RESULTS

The 3-month average treatment effect of surgery compared with nonoperative management was a 1.2-point reduction in pain [95% credible interval (CrI): 0.4-1.9] and an 8% absolute improvement in the Majeed score (95% CrI: 3%-14%). Similar results persisted to 1 year. Patients with initial fracture displacement ≥5 mm experienced a larger reduction in pain (2.2, 95% CrI: 0.9-3.5) compared with those patients with less initial displacement (0.9, 95% CrI: 0.1-1.8).

CONCLUSION

On average, surgical fixation likely provides a small improvement in pain and functional outcome for up to 12 months. Patients with ≥5 mm of posterior pelvic ring displacement are more likely to experience clinically important improvements in pain.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Effect of Intrawound Vancomycin Powder in Operatively Treated High-risk Tibia Fractures: A Randomized Clinical Trial

Importance

Despite the widespread use of systemic antibiotics to prevent infections in surgically treated patients with fracture, high rates of surgical site infection persist.

Objective

To examine the effect of intrawound vancomycin powder in reducing deep surgical site infections.

Design, Setting, and Participants

This open-label randomized clinical trial enrolled adult patients with an operatively treated tibial plateau or pilon fracture who met the criteria for a high risk of infection from January 1, 2015, through June 30, 2017, with 12 months of follow-up (final follow-up assessments completed in April 2018) at 36 US trauma centers.

Interventions

A standard infection prevention protocol with (n = 481) or without (n = 499) 1000 mg of intrawound vancomycin powder.

Main Outcomes and Measures

The primary outcome was a deep surgical site infection within 182 days of definitive fracture fixation. A post hoc comparison assessed the treatment effect on gram-positive and gram-negative-only infections. Other secondary outcomes included superficial surgical site infection, nonunion, and wound dehiscence.

Results

The analysis included 980 patients (mean [SD] age, 45.7 [13.7] years; 617 [63.0%] male) with 91% of the expected person-time of follow-up for the primary outcome. Within 182 days, deep surgical site infection was observed in 29 of 481 patients in the treatment group and 46 of 499 patients in the control group. The time-to-event estimated probability of deep infection by 182 days was 6.4% in the treatment group and 9.8% in the control group (risk difference, -3.4%; 95% CI, -6.9% to 0.1%; P = .06). A post hoc analysis of the effect of treatment on gram-positive (risk difference, -3.7%; 95% CI, -6.7% to -0.8%; P = .02) and gram-negative-only (risk difference, 0.3%; 95% CI, -1.6% to 2.1%; P = .78) infections found that the effect of vancomycin powder was a result of its reduction in gram-positive infections.

Conclusions and Relevance

Among patients with operatively treated tibial articular fractures at a high risk of infection, intrawound vancomycin powder at the time of definitive fracture fixation reduced the risk of a gram-positive deep surgical site infection, consistent with the activity of vancomycin.

Trial Registration

ClinicalTrials.gov Identifier: NCT02227446.

Initial experience with the T-Clamp for temporary fixation of mechanically and hemodynamically unstable pelvic ring injuries

In polytrauma patients with unstable pelvic ring injuries, pelvic binders interfere with femoral arterial access and are frequently removed for emergent endovascular and abdominal procedures. The 'trochanteric C-clamp' (T-clamp) is a novel technique described for rapid stabilization of the pelvis without fluoroscopic imaging, while ensuring adequate access to the groin. This case series reports the feasibility and safety following T-clamp application for unstable pelvic ring injuries in patients requiring simultaneous endovascular intervention. Between May 2018 - May 2019, seventeen patients with unstable pelvic ring injuries were treated with a T-clamp in conjunction with other emergent endovascular or intra-abdominal procedures. Nine presented with unstable APC injuries, seven with unstable LC injuries and one with a vertical shear pattern. Complications related to the T-clamp were prospectively collected. Following T-clamp application, there were two cases of intraoperative over-reduction, one of which required exchange for an anterior external fixator. This was the result of a concomitant acetabulum fracture leading to iatrogenic acetabular protrusion secondary to the T-clamp. Twelve cases maintained the T-clamp fixation postoperatively ranging from 1-3 days. One postoperative loss of reduction was noted and required exchange for anterior external fixator. In hemodynamically unstable patients who require emergent endovascular procedures, such as pelvic angiography and REBOA, T-clamp application offers a reasonably safe and effective method for expeditious stabilization of the pelvis while allowing unimpeded access to the abdomen, groin and pelvis. Caution should also be applied in patients with concomitant acetabulum fracture for risk of malreduction. Additionally, its prolonged postoperative use should be limited to patients who are not immediately suitable for fixation of the pelvis.

Complex Proximal Tibia Fractures: Workup, Surgical Approaches, and Definitive Treatment Options

Proximal tibia fractures including intra-articular plateau fractures are complex injuries that benefit from an algorithmic approach in terms of treatment to optimize outcomes and minimize complications. Certainly, nonsurgical treatment will be an option for some injuries; however, this chapter will focus on those injuries best addressed with surgicalsurgical treatment. Indications for surgical treatment include joint incongruity, joint instability and limb malalignment. In regard to surgical treatment, important considerations include appropriate management of the soft-tissue envelope, staged provisional reduction and stabilization versus immediate definitive fixation, single versus multiple surgical approaches, unilateral versus bicondylar fixation, and treatment of concomitant fracture-dislocation. This chapter describes surgical approaches to the proximal tibia ranging from the standard anterolateral to complex dual approaches or posterior approaches. Soft-tissue management becomes important due to the high-energy nature of these injuries with trauma both at the time of injury and then the surgical insult. Learning to identify and minimize these risks as well as addressing the soft-tissue defects that may require treatment is highlighted. Implant selection and fixation options for bicondylar plateau fractures will be discussed. Finally, use of nails, especially suprapatellar nails for proximal extra-articular proximal tibia fractures is described.

Surgeons Cannot Predict Pilon Fracture Outcomes Based on Initial Radiographs

This study sought to determine (1) whether surgeons can accurately predict functional outcomes of operative fixation of pilon fractures based on injury and initial postoperative radiographs, (2) whether the surgeon's level of experience is associated with the ability to successfully predict outcome, and (3) the association between patients' demographic and clinical characteristics and surgeons' prediction scores. A blinded, randomized provider survey was conducted at a level I trauma center. Seven fellowship-trained orthopedic traumatologists and 4 orthopedic trauma fellows who were blinded to outcome reviewed data regarding 95 pilon fractures in random order. Injury ankle radiographs, initial postoperative fixation radiographs, and brief patient histories were assessed. Midterm follow-up functional outcome scores obtained a mean 4.9 years after surgery were available for all patients. Main outcome measures were Pearson correlation coefficient-assessed functional outcomes and surgeon-predicted outcomes. A mixed-effect model determined the association between patients' characteristics and surgeons' prediction scores. Minimal positive correlation was observed between functional outcomes and prediction scores. No difference was noted between the attending and fellow groups in prediction ability. When surgeons' prediction confidence level was greater than 1 SD above the mean confidence level, correlation between functional outcome and prediction improved, although poor correlation was still observed. AO/OTA type 43C fractures, high-energy mechanisms, and older patient age were characteristics associated with lower prediction scores. Surgeons had poor ability to predict functional outcomes of patients with pilon fractures based on injury and initial postoperative radiographs, and level of experience was not associated with ability to predict outcome. [Orthopedics. 2020; 43(1): e43-e46.].

Management of Pelvic Fractures

Pelvic fractures are often the result of high-energy trauma and can result in significant morbidity. Initial management is focused on patient resuscitation and stabilization given the potential for life-threatening hemorrhage that is associated with these injuries. Radiographic evaluation and classification of the pelvic injury guides initial management, provisional stabilization, and preoperative surgical planning. Definitive reduction and fixation of the posterior and anterior pelvic ring is sequentially performed to restore stability and allow for mobilization and healing. Open techniques are commonly used for the pubic symphysis and displaced anterior and posterior ring injuries for which an acceptable reduction is unable to be obtained with closed or indirect techniques. Percutaneous fixation has become increasingly more common for both the anterior and posterior ring and utilizes screw placement within the osseous fixation pathways of the pelvis.

Effect of Training Modules on Hip Fracture Surgical Skills Simulation Performance: Early Validation of the AAOS/OTA Simulator

BACKGROUND

A preliminary validation study on a computer-based force-feedback simulation platform demonstrated the ability of the simulator to distinguish between novice and experienced users during a simulated hip-pinning procedure. The purpose of the present study was to further investigate whether the simulator and associated training modules are effective for improving user performance during simulated percutaneous hip-pinning procedures.

METHODS

With institutional review board approval, 24 medical students at our institution were randomized to "Trained" and "Untrained" groups. After a basic introduction, the Untrained group placed 3 guidewires in a valgus-impacted femoral neck fracture with use of the simulator. The Trained group completed 9 simulator-based training modules before performing the same task. Measured outcomes included an overall performance score and the distance from the pin to various ideals on the femoral neck, femoral head articular surface, and lateral cortex. Performance parameters were compared between groups with the Mann-Whitney U test.

RESULTS

The Trained group achieved a significantly higher overall score (median, 29) compared with the Untrained group (median, 6) (p < 0.01), outperformed the Untrained group in 4 specific performance metrics, and trended toward improvement over the Untrained group in 4 pin placement measures (p < 0.2).

CONCLUSIONS

Completion of novel training modules for percutaneous hip pinning on this fluoroscopic surgery simulator improves skill performance on simulator-based objective measurements and a simulated orthopaedic procedure compared with non-simulator-trained surgically inexperienced users. Improvement in the overall score and on 4 of 13 specific performance parameters implies that the training modules more effectively teach only certain motor and 3-dimensional spatial skills.

CLINICAL RELEVANCE

A valid platform such as the one described here has the potential to improve surgical education in orthopaedic trauma.

Anterior Intrapelvic Approaches: Fracture Patterns You May Want to Reconsider

The anterior intrapelvic approach with a lateral window is gaining popularity for the surgical treatment of anterior fracture patterns of the acetabulum. Certain fracture patterns and characteristics present challenges when using anterior approaches. This article aims to describe some of the fracture patterns that may be particularly difficult to address using the anterior intrapelvic approach with or without the lateral window.

Radiographic predictors of symptomatic screw removal after retrograde femoral nail insertion

INTRODUCTION

Removal of symptomatic implants is a common procedure performed by orthopaedic trauma surgeons. No guidance is available regarding which factors contribute to the likelihood of an implant becoming symptomatic. Our objective was to determine whether radiographic parameters associated with distal interlocks in retrograde femoral nails are associated with the rate of symptomatic screw removal.

PATIENTS AND METHODS

We conducted a retrospective review at a Level I trauma center. Study patients (n=442) had femoral fractures treated with retrograde intramedullary nails from 2007 to 2014 and at least 1year of follow-up. The main outcome measurement was symptomatic distal screw removal as predicted by radiographic parameters.

RESULTS

Symptomatic screw removal occurred in 12% of the patients. Increased distance between the most distal screw and the articular surface of the femur significantly reduced likelihood of symptomatic screw removal. A cutoff of 40mm from the articular block was predictive of removal (≥40mm, 0% removal; <40mm, 18% removal, p<0.0001). In patients with distal screws placed within 40mm of the articular surface of the femur, a ratio of screw length to distance between medial and lateral femoral cortices that was ≥1 was a strong predictor of symptomatic screw removal (area under Receiver Operating Characteristic curve, 0.75; p<0.0001).

CONCLUSIONS

More distal screws and screws that radiographically extend to or beyond the medial cortex are more likely to cause pain and require removal in femoral fractures treated with retrograde intramedullary nails. We identified a specific distance from the joint (<40mm) and a ratio of screw length to bone width (≥1) that significantly increased the likelihood of symptomatic screw removal. Clinicians can use these data to inform patients of the likely risk of implant removal and perhaps to better guide placement and length of screws when the clinical scenario allows some flexibility in location and length of screws.

Can applied external fixators be sterilized for surgery? A prospective cohort study of orthopaedic trauma patients

BACKGROUND

Temporary external fixators are often used to stabilize fractures when definitive fracture surgery must be delayed. Sometimes, external fixators are left in place during repeat operations, including definitive internal fixation of tibial pilon and tibial plateau fractures. It is unknown how well current surgical preparation sterilizes these devices, which become part of the surgical field. Our hypothesis was that our institution's standard surgical preparation creates a low rate of culture-positive environments on external fixators at the time of surgical skin incision.

METHODS

We prospectively consented and enrolled patients to obtain cultures (48 patients, 55 external fixators, 165 sets of culture data). After standard preparation and immediately before incision, cultures were obtained from three sites on each external fixator: 1) most distal pin 1cm from pin-skin interface, 2) most distal bar at midpoint between pin and clamp connectors, and 3) most distal clamp at bar-clamp interface. Our standard preparation for patients with external fixation in place is to don sterile gloves and wipe down all components of the external fixator with 70% alcohol-soaked sterile 4×4in gauze sponges before skin preparation. The skin and external fixator are then prepped in the usual fashion with ChloraPrep for closed wounds or with povidone iodine scrub and paint for open wounds. Swabs were processed and organisms from cultures identified. Clinicians were blinded to study results until study completion.

RESULTS

Two of 165 cultures (1.2%; 95% confidence interval [CI]: 0-2.9%) were positive for common pathogens sometimes observed in surgical site infection. Four cultures (2.4%; 95% CI: 0-4.8%) had pathogens that are rarely associated with surgical site infection, and four (2.4%; 95% CI: 0-4.8%) had nonpathogenic organisms.

CONCLUSION

Using 70% alcohol on external fixators plus either ChloraPrep for closed wounds or povidone iodine for open wounds seems to result in a low rate of positive cultures. Most species that were isolated are infrequently identified as sources of surgical site infections. This preparation protocol might be effective at producing a relatively clean environment at the time of surgery for patients with external fixators already in place.

Radiographic Determinants of Early Failure After Posterior Wall Acetabular Fracture Fixation

A retrospective review was conducted at an academic trauma center to determine whether fracture characteristics or aspects of native anatomy are predictive of early failure after fixation of posterior wall acetabular fractures. A chart review of posterior wall acetabular fractures treated from 2004 to 2009 yielded the study group that met the inclusion criteria. The study group included 18 consecutive patients who had clinical failure. The control group included 27 patients who did not have clinical failure. Operative notes were reviewed and axial view computed tomography scans were analyzed to determine 8 fracture descriptors (dislocation, comminution, marginal impaction, femoral head injury, incarcerated fragments, involvement of the subchondral arc, proximal-to-distal fracture extension, and size of the fracture measured by 3 methods) and 6 native anatomy descriptors (transverse plane acetabular anteversion, anterior acetabular sector angle, 2 measures of the posterior acetabular sector angle, and 2 measures of change in the posterior acetabular sector angle). Failure of treatment (n=18) was defined as the need for total hip arthroplasty (n=5) or the development of symptomatic posttraumatic arthritis (n=13). Fisher's exact test and Student's t test were conducted. The only variable that was predictive of failure of operative treatment of posterior wall fractures was extension of the fracture into the subchondral arc (12 of 18 patients in the failure group vs 7 of 27 patients in the nonfailure group, P=.01). Native anatomy, fracture size, and marginal impaction did not play a significant role in predicting failure. [Orthopedics. 2016; 39(6):e1104-e1111.].

Do traction radiographs of distal radial fractures influence fracture characterization and treatment?

BACKGROUND

Our center evaluates all distal radial fractures with traction radiographs before splinting. Although investigations of various imaging modalities to evaluate distal radial fractures have been presented in the literature, to our knowledge the use of traction radiographs has not been well described. We hypothesized that the addition of traction radiographs to standard radiographs increases interobserver and intraobserver reliability for injury descriptions, affects the choice of treatment plan, and decreases the perceived need for computed tomography.

METHODS

Radiographs for fifty consecutive eligible patients with distal radial fractures that were treated at a level-1 trauma center were used to create two image sets for each patient. Set 1 included injury and splint radiographs, and Set 2 included the images from Set 1 plus traction radiographs. The image sets were stripped of all demographic data and were presented in random order to seven fellowship-trained orthopaedic surgeons. The surgeons independently reviewed each of the 100 image sets and answered ten questions regarding the description and treatment of the injury. Analyses were conducted with kappa statistics to evaluate interobserver reliability. Intraobserver variability was assessed with the McNemar test after adjusting for clustering.

RESULTS

Traction radiographs improved interobserver reliability for four of ten questions. With regard to intraobserver variability, responses to two questions were significantly changed. With the addition of traction radiographs, the observation of intra-articular fragments requiring reduction increased from 38.3% to 53.1% (p &lt; 0.05) and the perceived need to order computed tomography for further evaluation decreased from 21.7% to 5.1% (p &lt; 0.001). No other changes reached significance.

CONCLUSION

The addition of traction radiographs appeared to affect surgeons' interobserver reliability in the evaluation of distal radial fractures. In addition, traction radiographs changed the rate of detection of intra-articular fragments requiring reduction and the perceived need for computed tomography. These data indicate that traction radiographs may provide some of the same information as computed tomographic scans at a lower cost and argue for additional research comparing computed tomographic scans and traction radiographs of the distal part of the radius.

Injury to the anterior tibial system during percutaneous plating of a proximal tibial fracture

Minimally invasive osteosynthesis of proximal tibial fractures has grown in popularity in recent years. This article describes a patient with a Schatzker type VI proximal tibial fracture (AO/OTA type 41.C3) and previous compartment syndrome treated with definitive fixation 8 weeks after initial injury with a precontoured proximal tibial plate and a distal targeting device. Brisk bleeding occurred during percutaneous insertion of a cortical screw at the midshaft of the tibia. Surgical exploration revealed sidewall tearing of the anterior tibial artery and vein, which were clipped at the screw insertion site. After the bleeding was controlled, the patient had a strong palpable posterior tibial pulse with no palpable dorsalis pedis pulse, and the foot remained well perfused. Function of the deep peroneal nerve was normal postoperatively. Previous concerns regarding the percutaneous treatment of proximal tibial fractures have focused on the risks of damage to the superficial peroneal nerve from distal screws. Based on cadaveric studies, percutaneously and laterally based screw placement in the distal tibial metaphysis threatens injury to the anterior tibial system. However, with alterations to the normal anatomy caused by severe trauma, previously described safe zones may be changed and neurovascular structures may be exposed to risk in locations that were previously thought safe.

Surgeon variability in the treatment of pelvic ring injuries

Pelvic ring injuries are associated with the potential for long-term disability and high mortality rates. No well-established, definitive treatment algorithms have been presented in the literature. We evaluated agreement among surgeons in selecting treatment of pelvic ring injuries and investigated the relationship between type of injury and treatment plan. We conducted a prospective agreement analysis of pelvic ring injury images at a level I regional trauma center. Eighty-nine isolated pelvic ring disruptions were selected; they were the only injuries present on the images and were thought to comprise a variety of pelvic fracture types from a database of 1600 pelvic fractures. Sets of injury images were randomly ordered and distributed to 5 orthopedic trauma surgeons blinded to patient name, attending surgeon, date of injury, and eventual treatment. Surgeons reviewed images, independently selected preferred treatments, and classified injuries with the Young-Burgess and Tile systems. Eight weeks later, images were again randomly ordered and distributed to the same 5 orthopedic surgeons, who again independently selected preferred treatments and classified injuries. Kappa analyses of agreement among surgeons and within each surgeon over time were conducted. Analysis among surgeons' treatment plans based on radiographic assessment alone revealed a mean kappa value of 0.47, indicating moderate level of agreement. Analysis of data collected 8 weeks later yielded a mean kappa value of 0.56, representing moderate agreement within each surgeon over time. Young-Burgess and Tile classifications yielded consistent treatment plans for certain fracture types and varied plans for other types. Our results question the usefulness of the 2 classification systems for predicting treatment decisions.

Classification of pelvic fractures: analysis of inter- and intraobserver variability using the Young-Burgess and Tile classification systems

Classification systems for pelvic ring injuries have been developed to assist in understanding the anatomy of the injury, predicting prognosis, and helping define treatment. Despite the frequent clinical use of the Young-Burgess and Tile classification systems, to our knowledge little work has been conducted to validate either system. We assessed the degree of inter- and intraobserver variability when using both the Young-Burgess and Tile classification systems and thereby assessed their validity for clinical use. Eighty-nine isolated pelvic ring disruptions were selected. Sets of injury images were randomly ordered and distributed to 5 orthopedic trauma surgeons blinded to the patients' names, attending surgeons, dates of injury, and eventual treatments. The surgeons were asked to independently classify each pelvic ring disruption based on the Young-Burgess and Tile classifications. Eight weeks later, the same images were randomly ordered and redistributed to the same 5 surgeons, who were again asked to classify the pelvic injuries. A kappa analysis was conducted to analyze agreement among surgeons. A moderate degree of agreement was shown among orthopedic trauma surgeons when using both the Young-Burgess and Tile classification systems. Intraobserver agreement was found to be substantial for the Young-Burgess classification and moderate for the Tile classification. The degree of inter- and intraobserver variability may limit the usefulness of the 2 classification systems, both clinically and for research purposes.

Are locking screws advantageous with plate fixation of humeral shaft fractures? A biomechanical analysis of synthetic and cadaveric bone

OBJECTIVES

To investigate whether locking screws offer any advantage over nonlocking screws for plate fixation of humeral shaft fractures for weight-bearing applications.

DESIGN

: Mechanical evaluation of stiffness in torsion, bending, and axial loading and failure in axial loading in synthetic and cadaveric bone.

SETTING

Biomechanical laboratory in an academic medical center.

METHODS

: We modeled a comminuted midshaft humeral fracture in both synthetic and cadaveric bone. Humeri were plated posteriorly. Two study groups each used identical 10-hole, 3.5-mm locking compression plates that can accept either locking or nonlocking screws. The first group used only nonlocking screws and the second only locking screws. Stiffness testing and failure testing were performed for both the synthetic bones (n = 6) and the cadaveric matched pairs (n = 12). Fatigue testing was set at 90,000 cycles of 440 N of axial loading.

MAIN OUTCOME MEASURES

Torsion, bending, and axial stiffness and axial failure force after cyclic loading.

RESULTS

With synthetic bones, no significant difference was observed in any of the 4 tested stiffness modes between the plates with locking screws and those with nonlocking screws (anteroposterior, P = 0.51; mediolateral, P = 0.50; axial, P = 0.15; torsional, P = 0.08). With initial failure testing of the constructs in axial loading, both plates failed above anticipated physiologic loads of 440 N (mean failure load for both constructs >4200 N), but no advantage to locking screws was shown. The cadaveric portion of the study also showed no biomechanical advantage of locking screws over nonlocking screws for stiffness of the construct in the 4 tested modes (P > 0.40). Fatigue and failure testing showed that both constructs were able to withstand strenuous fatigue and to fail above anticipated loads (mean failure >3400 N). No difference in failure force was shown between the 2 groups (P = 0.67).

CONCLUSIONS

Synthetic and cadaveric bone testing showed that locking screws offer no obvious biomechanical benefit in this application.

Growth factor modulation of distraction osteogenesis in a segmental defect model

A model was established in 39 dogs to investigate the growth factor modulation of regenerate bone in distraction osteogenesis. A segment of the diaphysis of the radius was resected unilaterally. An osteotomy was made proximal to the segmental defect to create a transport segment. A monolateral external fixator was applied. After a latency period, the segment was transported across the defect. One week after the transport assembly contacted the distal pin clamp, an ipsilateral osteotomy of the proximal ulna was performed. In 20 dogs, transforming growth factor-beta was injected into the regenerate bone halfway through the transport period. Four dogs were sacrificed before docking, when the regenerate bone was still immature. In specimens harvested halfway through the transport period, evidence was found of intramembranous ossification during distraction. In specimens harvested after the transport assembly contacted the distal pin clamp, evidence was found that the mature regenerate formed by endochondral ossification. Therefore, a combined mechanism of ossification is proposed for this segmental defect model that includes mechanical stimulus for bone differentiation. The one-time administration of transforming growth factor-beta retarded the formation of a stable, united regenerate. It is concluded that transforming growth factor-beta caused an effect opposite to that which was desired.

Evaluation of recombinant human bone morphogenetic protein-2 as a bone-graft substitute in a canine segmental defect model

A study was performed in dogs to evaluate the dose-response characteristics and effectiveness of recombinant human bone morphogenetic protein-2 with a collagen sponge carrier in a segmental defect model. Twenty-seven dogs underwent bilateral radial osteotomies with creation of a 2.5-cm diaphyseal defect. All received autogenous cancellous bone graft in one defect and a collagen implant in the other. These implants contained recombinant human bone morphogenetic protein-2 at the following doses: group 1 at 0 microg (three dogs, 0 microg/ml total implant volume), group 2 at 150 microg (three dogs, 50 microg/ml), group 3 at 600 ,g (three dogs, 200 microg/ml), group 4 at 2,400 microg (three dogs, 800 microg/ml), group 5 at 0 microg (five dogs, 0 microg/ml), group 6 at 150 microg (five dogs, 200 microg/ml), and group 7 at 600 microg (five dogs, 50 microg/ml). The defects were stabilized with external fixators. The dogs in groups 1-4 were killed at 12 weeks postoperatively, and those in groups 5-7 were killed at 24 weeks postoperatively except for one dog in group 7, which was killed at 48 weeks. Evaluation included monthly radiographs, biomechanical testing, and nondemineralized histology. All 27 radii with autogenous cancellous bone graft and all 19 implants treated with recombinant human bone morphogenetic protein-2 achieved radiographic and histologic union and gross stability. The eight radii treated with collagen carrier alone went on to radiographic and histologic nonunion and were grossly unstable at death. A dose-dependent occurrence of cyst-like bone voids was noted radiographically and histologically. Biomechanical performance tended to be better at the lowest dose studied at 12 weeks, and all three doses performed better than the placebo (p < 0.05) at 12 and 24 weeks. By 24 weeks, radiolucent areas corresponding to histologic bone voids persisted radiographically, although there was evidence of early bone remodeling. This remodeling progressed to 48 weeks in the single animal followed to this time point, although bone voids remained. These radiologic findings were confirmed histologically. Recombinant human bone morphogenetic protein-2 in a collagen sponge carrier has significant osteoinductive activity in this canine segmental defect model. A dose-response relationship is evident, with heterotopic bone and cyst-like void formation at higher doses and a minimum effective dose of 0-150 microg. At 12 and 24 weeks postoperatively, biomechanical parameters achieved by defects treated with recombinant human bone morphogenetic protein-2 were comparable with those of autograft controls and were significantly stronger than those of the placebo (p < 0.05).

Evaluation of bovine-derived bone protein with a natural coral carrier as a bone-graft substitute in a canine segmental defect model

The efficacy of a bone-graft substitute (bovine-derived bone protein in a carrier of natural coral) in the healing of a segmental defect of a weight-bearing long bone was evaluated. Twenty dogs, divided into two groups, underwent bilateral radial osteotomies with creation of a 2.5 cm defect. On one side of each dog, the defect was filled with autogenous cancellous bone graft. Contralateral defects received, in a blinded randomized fashion, cylindrical implants consisting of natural coral (calcium carbonate) or calcium carbonate enhanced with a standard dose of bovine-derived bone protein (3.0 mg/implant; 0.68 mg bone protein/cm3). The limbs were stabilized with external fixators, and all animals underwent monthly radiographs. They were killed at 12 (group 1) or 24 (group 2) weeks, and regenerated bone was studied by biomechanical testing and histology. Radiographic union developed in all 20 radii with autogenous cancellous bone grafts and in all 10 of the radii with the composite implants. None of the radii with implants of calcium carbonate alone showed radiographic evidence of union. This represented a statistically significant difference between implant types. In addition, calcium carbonate implants both with and without bone protein demonstrated radiographic evidence of near total resorption of the radiodense carrier by 12 weeks. This resorption facilitated radiographic evaluation of healing. Mean values for biomechanical parameters of radii with the composite implants exceeded those for the contralateral controls at 12 and 24 weeks; the difference was statistically significant at 12 weeks. Histology revealed scant residual calcium carbonate carrier at either time in the defects with calcium carbonate implants; however, a moderate amount was present in defects with the composite implants. In these specimens, the residual carrier was completely surrounded by newly formed bone that may have insulated the calcium carbonate from further degradation. The present study used a carrier of granular calcium carbonate reconstituted with bovine type-I collagen to deliver an osteoinductive protein to the defect site. This carrier is of nonhuman origin (eliminating the risk of disease transmission or antigenicity) and resorbs rapidly. In this model, bovine-derived bone protein in a natural coral carrier performed consistently better than the gold standard autogenous cancellous bone graft in terms of the amount of bone formation and strength of the healed defect. This may have implications for removal of hardware or resumption of weight-bearing in certain clinical situations. These data also indicate that coralline calcium carbonate alone represents a poor option as a bone-graft substitute in this critical-sized segmental defect model.

Bovine-derived bone protein as a bone graft substitute in a canine segmental defect model

OBJECTIVES

To evaluate the efficacy of a bone graft substitute in healing of a segmental defect of a weight-bearing long bone.

DESIGN

An established canine model was used to perform a blinded, prospective, randomized study of the performance of bone graft substitute implants. This performance was compared with that of an accepted treatment modality (autograft) in a paired fashion.

SETTING

An accredited animal research facility.

SUBJECTS AND INTERVENTION

Twenty-eight dogs underwent bilateral radial osteotomies with creation of a 2.5-centimeter defect. On one side, the defect in every dog was filled with autogenous cancellous bone graft (ABG). Contralateral defects received, in a blinded, randomized fashion, cylindrical implants of demineralized bone matrix (DBM) allograft or DBM plus a constant dose (3.0 milligrams) of bovine-derived bone protein (DBM + BP). The defects were stabilized by external fixation. Subjects underwent monthly radiographs and were killed at six, twelve, or twenty-four weeks. Regenerate bone was studied by biomechanical testing and histology. Six animals were studied to determine the dose-response characteristics of the protein preparation. Three received implants containing 0.3 milligram of BP (group 1) and three received 1.0 milligram of BP (group 2). These animals were killed at twelve weeks of follow-up.

RESULTS

All twenty-eight ABG radii (100 percent) progressed to radiographic union, as did thirteen of thirteen (100 percent) DBM + BP radii compared with only four of fifteen (27 percent) of DBM radii. The difference between union rates was statistically significant (p < 0.05). Mean values for most biomechanical parameters of DBM + BP radii exceeded those of their contralateral ABG controls at twelve and twenty-four weeks, whereas those for DBM implants did not. Histology revealed microscopic evidence of normal bone healing in all ABG and DBM + BP radii, whereas most DBM radii demonstrated nonunions. In the dose-response arm of the study, six of six ABG radii (100 percent) achieved union; zero of three (0 percent) of group 1 and two of three (67 percent) of group 2 radii achieved grossly stable unions. Biomechanical testing was consistent with radiographic results, indicating that the 3.0-milligram dose was the most effective of those studied.

CONCLUSIONS

The DBM + BP composite implants were more effective at healing critical-sized segmental defects than DBM alone in this canine model when a 3.0-milligram per implant dose of BP was used. Biomechanical and histologic properties of the regenerated bone formed by DBM + BP implants was comparable to that of cancellous autograft.

Porous ceramics as bone graft substitutes in long bone defects: a biomechanical, histological, and radiographic analysis

Three porous ceramic bone graft materials were compared with regard to their ability to heal a 2.5 cm defect created surgically in a bilateral canine radius model. The ceramic materials were analyzed at 12 and 24 weeks after surgery and included tricalcium phosphate, hydroxyapatite, and collagen hydroxyapatite, which contained a mixture of 35% tricalcium phosphate and 65% hydroxyapatite with added collagen. Each material was evaluated alone and with added bone marrow aspirate. All the implants were compared with a graft of autogenous cancellous bone in the contralateral radius. Biomechanical testing and radiographic evaluation revealed that the addition of bone marrow aspirate was essential for tricalcium phosphate and hydroxyapatite to achieve results comparable with those of cancellous bone. Collagen hydroxyapatite performed well without the addition of bone marrow, although the addition of marrow did have a positive effect. Further qualitative radiographic and histological analysis demonstrated that tricalcium phosphate was the only ceramic that showed any sign of degradation at 24 weeks. This observed degradation proved to be an important factor in evaluating radiographs because the radiodensity of collagen hydroxyapatite and hydroxyapatite interfered with the determination of radiographic union. At 24 weeks, tricalcium phosphate with bone marrow was the material that performed most like cancellous bone. In this study, the biomechanical and radiographic parameters of tricalcium phosphate with bone marrow were roughly comparable with those of cancellous bone at 12 and 24 weeks. Tricalcium phosphate was the only implant that showed significant evidence of degradation at 24 weeks by both histological and radiographic evaluations, and this degradation took place only after a degree of mechanical competence necessary for weight-bearing was achieved.

Effects on pulmonary physiology of reamed femoral intramedullary nailing in an open-chest sheep model

We have recently developed an open-chest sheep model to monitor and study the effects of major orthopedic procedures on pulmonary physiology. In this pilot study, we focused on reamed intramedullary femoral nailing in animals without pulmonary injury. Details of the model are described herein. The control group consisted of sheep that underwent thoracotomy and invasive monitoring only, while the study group also underwent femoral osteotomy, reaming, and intramedullary nailing. Baseline, postthoracotomy, and post-reaming/nailing values were recorded for mean pulmonary arterial pressure, central venous pressure, left arterial pressure, dynamic compliance, arterial blood gas, mixed venous O2, cardiac index, and mean arterial pressure so that hemodynamic and oxygen transport data could be calculated. Postprocedure values were recorded at hourly intervals for 4 h. A physiologically stable, reproducible model was created. No statistically significant differences were found between the control and experimental groups, indicating no adverse effect of femoral reaming/nailing. In one animal, using echocardiography, pulmonary embolization was documented while reaming and inserting the intramedullary nail. Reamed femoral intramedullary nailing is not detrimental to sheep with otherwise normal lungs. This finding suggests that femoral reaming and nailing in trauma patients without associated pulmonary injuries and otherwise normal lungs may be carried out without risk of inducing significant respiratory complications.

Evaluation of ground cortical autograft as a bone graft material in a new canine bilateral segmental long bone defect model

The recent orthopaedic literature reflects a growing number of bone graft substitutes and osteogenic growth factors under investigation in a number of animal models. We attempted to establish a well-controlled, large animal model of a segmental defect in a weight-bearing long bone by developing a bilateral diaphyseal radial defect model in the canine. We also evaluated the effectiveness of ground cortical autograft as a graft material. Twenty-three adult mongrel dogs underwent bilateral radial osteotomies with creation of a 2.0-2.5-cm diaphyseal defect on each side. All dogs received cancellous autograft (CAN) on one side, nine received no graft material (DEF) on the opposite side, and 14 received morselized cortical autograft (CORT) on the opposite side. Radii were stabilized by external fixation. Animals were followed radiographically at 6-week intervals to evaluate the healing process. Thirteen dogs were sacrificed at short-term follow-up (8-12 weeks postsurgery) and 10 at long-term (16-24 weeks). Biomechanical torsion testing to failure and histological evaluation were performed on each defect. All CAN radii achieved union (100%) while only one of nine DEF radii (11%) and none of 14 (0%) of CORT radii achieved union. Statistically significant differences in biomechanical parameters between both test groups and their corresponding autograft control radii were found. Histology revealed fibrous nonunions in the DEF and CORT radii. These results demonstrate that the bilateral canine radial defect model represents a consistent and reproducible model for bone healing of segmental defects in weight-bearing long bones and that ground cortical autograft is an ineffective graft material.

Cytogenetic, telomere, and telomerase studies in five surgically managed lumbosacral chordomas

Lumbosacral chordomas are rare skeletal sarcomas of the spine that originate from the remnant notochord. The understanding of this human cancer is limited to observations of its clinical behavior and its embryonic link. Thus, we performed chromosome and molecular analyses from five surgically harvested chordomas in an effort to document genetic and biochemical abnormalities which might aid in understanding the tumor biology of this understudied neoplasm. Cytogenetic analysis of the five chordomas revealed normal results in four patients and random abnormalities in only one tumor cell in the 100 cells studied from the fifth patient. A repeat telomeric probe (TTAGGG)50 was hybridized to genomic DNA isolated from chordoma cells (and HeLa cells) and digested with HinfI. The tumor DNA was paired with leukocyte DNA from age-matched controls and revealed telomere elongation in four of the four chordoma patients studied with molecular genetic techniques. Conversely, telomere length reduction has been reported during in vitro senescence of human fibroblasts, giant cell tumor of bone, colon cancer, intracranial tumors, childhood leukemia, Wilms tumor, and in HeLa cells. Telomerase activity (telomerase is required to maintain telomere integrity) was also determined by visualizing the extension of radioactive telomeric repeats on DNA sequencing gels. The telomeric fragments were assembled during incubation of the cytoplasmic extract containing telomerase. Telomerase activity was observed in HeLa (positive control and commercially available cell line), giant cell tumor of bone (positive control tumor cells from living patients), and in chordoma cells from one of the two chordoma patients (but to a lesser degree compared with HeLa). As expected, the chordoma patients' fibroblasts exhibited no telomerase activity.

Telomerase activity and oncogenesis in giant cell tumor of bone

BACKGROUND

Benign giant cell tumor of bone (GCT) is a primary skeletal neoplasm with an unpredictable pattern of biologic aggressiveness and cytogenetic findings characterized by telomeric associations and telomeric reduction. The role of maintaining telomeric integrity is performed by telomerase. To determine if telomerase activity is present, cell extracts from fibroblasts and tumor cells from five patients with GCT were analyzed and compared with HeLa (a positive control cell line).

METHODS

Telomerase activity was detected by visualizing the extension of radioactive telomeric repeats on DNA sequencing gels. Telomere reduction was assessed using southern blot analyses of the restriction enzyme Hinf I digested DNA with a radio-labeled telomere probe.

RESULTS

Telomerase or telomerase-like activity was detected in the cell extracts from HeLa and tumor cells. However, GCT telomerase activity varied and was less than that observed in HeLa, but no activity was detected from fibroblasts. In addition, telomere reduction was seen in DNA isolated from both HeLa and GCT but not in fibroblasts or age-matched controls.

CONCLUSION

Telomere reduction and telomerase activity may be oncogenic sustaining events required to maintain the transformed phenotype seen in GCT.

Tubular adenoma of the main pancreatic duct

We report a case of tubular adenoma of the duct of Wirsung with focal villous changes. To our knowledge, this is the 13th reported case of this uncommon neoplasm and the first with a primarily tubular histologic pattern. The patient presented with abdominal pain and diarrhea and was found on endoscopic retrograde cholangiopancreaticography to have a mass in the head of the pancreas, which was confirmed by endoscopic ultrasound. Clinical and pathological features of the 12 previously reported cases are reviewed. Intraoperative testing failed to rule out adenocarcinoma which, in addition to difficulties presented by local anatomic relationships of the tumor, supports wide surgical resection as the preferred surgical solution.