Thomas F. Higgins

Biomechanical analysis of distal femur fracture fixation : Fixed-angle screw-plate construct versus condylar blade plate

Objective: The objective of this study is to establish the relative strength of fixation of a locking distal femoral plate compared with the condylar blade plate. Methods: Eight matched pairs of fresh-frozen cadaveric femurs were selected and evaluated for bone density. A gap osteotomy model was used to simulate an OTA/AO A3 comminuted distal femur fracture. One femur of each pair was fixed with the blade plate; the other, with a locking plate. After 100 N preload and 10,000 cycles between 100 N and 1000 N, total displacement of each specimen was assessed. After completion of cyclic loading, maximum load to failure was tested. Results: Significantly greater subsidence (total axial displacement) occurred with the blade plate (1.70 ± 0.45 mm; range, 1.21-2.48 mm) than with the locking plate fixation (1.04 ± 0.33 mm; range, 0.67-1.60 mm) after cyclic loading (P = 0.03). In load-to-failure testing, force absorbed by the locking plate before failure (9085 ± 1585 N; range, 7269-11,850 N) was significantly greater than the load tolerated by the blade plate construct (5591 ± 945 N; range, 3546-6684 N; P = 0.001). Variability in bone mineral density did not affect the findings (fixed angle distal femoral plate r2 = 0.1563; condylar blade plate r2 = 0.0796). Conclusions: The locking screw-plate construct proved stronger than the blade plate in both cyclic loading and ultimate strength in biomechanical testing of a simulated A3 distal femur fracture. Although differences were small, the biomechanical performance of the locking plate construct over the blade plate may lend credence to use of the locking plate versus the blade plate in the fixation of comminuted distal femur fractures.

Computerized Adaptive Testing Using the PROMIS Physical Function Item Bank Reduces Test Burden With Less Ceiling Effects Compared With the Short Musculoskeletal Function Assessment in Orthopaedic Trauma Patients

Purpose: Patient-reported outcomes are important to assess effectiveness of clinical interventions. For orthopaedic trauma patients, the short Musculoskeletal Function Assessment (sMFA) is a commonly used questionnaire. Recently, the Patient-Reported Outcome Measurement Information System (PROMIS) PF Function Computer Adaptive Test (PF CAT) was developed using item response theory to efficiently administer questions from a calibrated bank of 124 PF questions using computerized adaptive testing. In this study, we compared the sMFA versus the PROMIS PF CAT for trauma patients. Methods: Orthopaedic trauma patients completed the sMFA and the PROMIS PF CAT on a tablet wirelessly connected to the PROMIS Assessment Center. The time for each test administration was recorded. A 1-parameter item response theory model was used to examine the psychometric properties of the instruments, including precision and floor/ceiling effects. Results: One hundred fifty-three orthopaedic trauma patients participated in the study. Mean test administration time for PROMIS PF CAT was 44 seconds versus 599 seconds for sMFA (P < 0.05). Both instruments showed extremely high item reliability (Cronbach alpha = 0.98). In terms of instrument coverage, neither instrument showed any floor effect; however, the sMFA revealed 14.4% ceiling effect, whereas the PROMIS PF CAT had no appreciable ceiling effect. Conclusions: Administered by electronic means, the PROMIS PF CAT required less than one-tenth the amount of time for patients to complete than the sMFA while achieving equally high reliability and less ceiling effects. The PROMIS PF CAT is a very attractive and innovative method for assessing patient-reported outcomes with minimal burden to patients.

Biomechanical Analysis of Bicondylar Tibial Plateau Fixation: How Does Lateral Locking Plate Fixation Compare to Dual Plate Fixation?

Objectives: This study is designed to test the comparative strength of lateral-only locked plating to medial and lateral nonlocked plating in a cadaveric model of a bicondylar proximal tibial plateau fracture. Methods: Ten matched pairs of human cadaveric proximal tibia specimens were used for biomechanical testing. Cyclic loading using a materials testing device simulated initial range of motion and load bearing following surgical repair. Subsidence of the medial and the lateral condyles was measured following 10,000 cycles from 100N to 1,000N; the maximum load to failure on the medial condyle for both plate constructs was also measured. Results: On the lateral side, dual plating (DP) allowed an average of 0.68 ± 0.14 mm of subsidence, compared with 1.03 ± 0.27 mm for the fixed-angle plate (FAP) (P = 0.077). On the medial side, DP allowed an average of 0.78 ± 0.15 mm of subsidence, compared with 1.51 ± 0.32 mm for the FAP (P = 0.045). No significant difference was found in the maximal load to medial condyle fixation failure between either plating construct (P = 0.204). Conclusions: The results of this study demonstrate that dual-plate fixation allows less subsidence in this bicondylar tibial plateau cadaveric model when compared to isolated locked lateral plates. This may raise concerns about the widespread use of isolated lateral locked plate constructs in bicondylar tibial plateau fractures.

Cortical heat generation using an irrigating/aspirating single-pass reaming vs conventional stepwise reaming.

Objective: To compare the heat generation and pressure generation of a prototype irrigating aspirating intramedullary reaming system to traditional stepwise reaming. Design: This in vitro study used 8 pairs of fresh-frozen human cadaver tibias. Thermocouples were mounted in the mid-diaphysis and distal diaphysis. A pressure transducer was placed distally to assess intramedullary pressure, a load cell measured axial load was applied by the surgeon, and the entire construct was placed in a 37°C saline bath. One specimen from each pair underwent single-pass reaming with the prototype reamer irrigator aspirator (RIA), and the contralateral limb underwent standard stepwise reaming. All variables were recorded. Results: There were no significant differences in pressure applied to the load cells during reaming. The maximum temperatures reached in the distal diaphysis in the RIA group (42.0 ± 9.1°C) were significantly lower (P = 0.025) than in the standard reaming group (58.7 ± 15.9°C). The maximum pressure generated in the distal tibia in the RIA group (32.7 ± 39.4 kPa) was significantly higher (P = 0.019) than in the standard reaming group (17.0 ± 32.6 kPa). Conclusions: This study demonstrated substantially decreased temperatures with the RIA prototype when compared with standard stepwise reaming. It appears that the continuous flow of room temperature saline irrigant into the system manages to cool the cortical bone, despite the aggressive nature of a single-pass reaming method. However, in this model, contrary to the findings of other studies, the RIA system did generate higher pressures in the distal tibial metaphysis, perhaps as a result of congestion within the outflow of the RIA system. The results of this study confirm that cortical heat generation is not a problem but definitely indicate further development of this prototype aspirator function is warranted, followed by careful in vivo evaluation.

Incidence and Morphology of the Posteromedial Fragment in Bicondylar Tibial Plateau Fractures

Objectives: Bicondylar tibial plateau fractures featuring extensive articular involvement have a record of mixed clinical results. Recent discussion has focused on the significance of a posteromedial articular fragment in bicondylar injuries. This fragment has often gone unrecognized or has not been addressed. The posteromedial fragment is defined as any posteriorly based articular fracture of the medial plateau with the fracture line exiting the medial cortex. This study is designed to produce a detailed description of the incidence, size, and shape of this fracture, as this may be helpful in driving the choice of both approach and fixation for these injuries. Furthermore, a better understanding of this fractures morphology may lead to a better ability to model the biomechanical reliability of laterally based locking fixation in securing the reduction of this fracture fragment. Design: Retrospective study of patient records and computed tomography scans. Setting: Level I university regional trauma center. Patients: All patients treated for bicondylar tibial plateau fracture from January 1, 2002, through August 31, 2007. Results: One hundred forty-eight patients were identified in the 5.5-year period, and 111 had complete computed tomography records (75%). Of 111 bicondylar tibial plateau fractures analyzed, this fragment occurred in 65 cases (59% incidence) and on average accounted for 25% of the total tibial plateau joint surface. There was greater than 5 mm of articular displacement in 55% of cases. The posteromedial fragment exhibits a vertical fracture pattern (average sagittal angle 73 degrees), suggestive of shear instability and vertical displacement. Conclusions: Given the high frequency, significant portion of the joint involved, significant displacement, and pattern suggestive of instability, surgeons need to be cognizant of this pattern and may need to consider directly reducing and fixating this fragment through a posteromedially based approach. Overall morphologic findings of the posteromedial fragment are highly consistent with other recent data on this pattern. This information may also be useful in modeling fracture fixation for future study.

A biomechanical analysis of fixation of intra-articular distal radial fractures with calcium-phosphate bone cement.

Background: Calcium phosphate cement has been used to treat unstable fractures of the distal end of the radius with the intent of avoiding the stiffness and morbidity associated with prolonged immobilization in a cast or external fixation. The purpose of this study was to compare the stability of the fracture fragments after fixation with augmented calcium phosphate cement with that after alternative methods of percutaneous fracture treatment.Methods: Both an osteotomy and osteoclasis were used to create a model of an intra-articular fracture of the distal part of the radius (AO type C2) with dorsal bone loss in seven pairs of fresh-frozen upper extremities. One wrist from each pair was fixed with an external fixator and three Kirschner wires, and the contralateral wrist was fixed with calcium phosphate cement (Norian SRS) and three Kirschner wires (augmented calcium phosphate cement). Sequentially increasing loads, up to a total of 100 N, were then applied to the major flexors and extensors of the wrist. Fracture fragment motion was measured by the Optotrak three-dimensional system.Results: Fixation with cement alone failed at the bone-cement interface at <80 N in all specimens. With use of an analysis of variance, augmented external fixation was found to provide significantly increased stability to the radial fragment compared with that provided by augmented calcium phosphate cement in four of the six axes tested (e.g., mean motion [and standard deviation] in flexion-extension was 3.0° ± 2.93° versus 11.1° ± 13.08°, respectively; p = 0.001). Augmented calcium phosphate cement was found to provide greater stability for the radial fragment than were Kirschner wires alone in three axes (e.g., mean motion in flexion-extension was 11.1° ± 13.08° versus 36.5° ± 13.03°, respectively; p = 0.001).Conclusions: Calcium phosphate cement alone is insufficient to withstand physiologic flexion-extension motion of the wrist without supplemental wire fixation. When supplemented with Kirschner wires, fixation with bone cement is more stable than are Kirschner wires alone, but it is significantly less stable than augmented external fixation.Clinical Relevance: When performing studies of fracture fixation strengths, it is essential to simulate the shear and rotational forces encountered during normal wrist motion. On the basis of the physiologic biomechanical testing in this study, we recommend supplemental fixation if calcium phosphate cement is chosen for fixation of unstable distal radial fractures.

Rates of Prescription Opiate Use Before and After Injury in Patients with Orthopaedic Trauma and the Risk Factors for Prolonged Opiate Use

BACKGROUND The prudent use of prescription opiate medications is a central aspect of postoperative pain management. The mortality associated with prescription opiate overdose is reaching epidemic proportions nationally, and is the leading cause of accidental death in greater than half the states in the United States. This study sought to determine the rates of preinjury opiate use in patients with orthopaedic trauma and the risk factors for prolonged use postinjury. METHODS The Utah Controlled Substance Database was queried to determine the use of prescription opiates by all patients admitted to the orthopaedic trauma service for a two-year period with isolated musculoskeletal injuries. Usage three months prior to injury and six months postinjury was examined. RESULTS Six hundred and thirteen patients met inclusion criteria. Among patients with orthopaedic trauma, 15.5% had filled a prescription for opiates in the three months prior to injury, compared with 9.2% of the general population (p < 0.001). More than one prescription was filled by 12.2% of the patients with trauma preinjury compared with 6.4% of the general population (p < 0.001). Postoperatively, 68.4% of all patients filled opiate prescriptions for less than six weeks, 11.9% filled opiate prescriptions between six and twelve weeks, and 19.7% filled opiate prescriptions past twelve weeks. Patients with preinjury use of more than one opiate prescription in the three months preinjury were six times as likely to continue use past twelve weeks, and 3.5 times as likely to obtain opiates from a provider other than their surgeon (p < 0.001). Opiate use was briefest with upper-extremity injuries, followed by lower-extremity injuries and pelvic or acetabular injuries. Regression models demonstrate that risk factors for prolonged use of opiates include advancing age and extent of preinjury use. CONCLUSIONS Patients with orthopaedic trauma are significantly more likely than the general population to use prescription opiates prior to injury. Preinjury opiate use is predictive of prolonged use postinjury and predictive of patients who will seek opiates from other providers.

Lower Extremity Assessment Project (LEAP)--the best available evidence on limb-threatening lower extremity trauma.

Lower Extremity Assessment Project (LEAP) study set out to answer many of the questions surrounding the decision of whether to amputate or salvage limbs in the setting of severe lower extremity trauma. A National Institutes of Health-funded, multicenter, prospective observational study, the LEAP study represented a milestone in orthopedic trauma research, and perhaps in orthopedics. The LEAP study attempted to define the characteristics of the individuals who sustained these injuries, the characteristics of their environment, the variables of the physical aspects of their injury, the secondary medical and mental conditions that arose from their injury and treatment, their ultimate functional status, and their general health. In the realm of evidence-based medicine, the LEAP studies provided a wealth of data, but still failed to completely determine treatment at the onset of severe lower extremity trauma.

Postoperative Opioid Administration Inhibits Bone Healing in an Animal Model

BackgroundThe current mainstay of orthopaedic pain control is opioid analgesics but there are few studies in the literature evaluating the effects of opioids on bone healing.Questions/purposesThe purpose of this study was to use a rat fracture model to evaluate the effects of opioid administration on osseous union in the acute (4 weeks) and subacute (8 weeks) setting in an operatively stabilized fracture. We asked the following question: does morphine administration alter (1) fracture callus strength; (2) callus volume and formation; and (3) morphology and early remodeling to final osseous union?MethodsA 0.4-mm femoral osteotomy gap was created in 50 Sprague-Dawley rats using an established model. Postoperatively, rats were randomized to control versus morphine-treated study groups. Equal numbers of rats from each group were euthanized at 4 weeks and 8 weeks postoperatively. Three-point bend biomechanical testing was performed to evaluate postoperative callus strength. Micro-CT scans and histological analyses were used to evaluate postoperative callus volume and formation, morphology, and features of early remodeling.ResultsBiomechanical testing identified a statistically significant (p = 0.048) reduction in callus strength in morphine-treated animals 8 weeks postoperatively compared with controls. Radiographic and histological analysis showed delayed callus maturation and lack of remodeling in the morphine group compared with control animals at 8 weeks. Micro-CT analysis expressed remodeling and resorption as a decrease in callus volume over the two time points. The control group had significant levels of resorption decreasing 29% (p = 0.023) over the 4-week to 8-week time interval. Morphine administration inhibited callus resorption and remodeling with only a 13% decrease (p = 0.393) in callus volume comparing these time points. The callus inhibition associated with morphine administration was not as evident in the acute, 4-week time setting.ConclusionsMorphine administration inhibited callus strength in this animal model. This finding is likely consistent with the observation that the callus and healing bone appear to have a decreased rate of maturation and remodeling seen at 8 weeks.Clinical RelevanceThis study identifies that administration of an opioid pain medication leads to weaker callus and impedes callus maturation compared with controls. These findings may provide the impetus to alter our current orthopaedic analgesic gold standard toward more multimodal and opioid-limiting pain control regimens.

Continuous peripheral nerve blockade as postoperative analgesia for open treatment of calcaneal fractures.

Objective: To examine the cost and efficacy of methods of general and regional anesthetic for postoperative pain control after open repair of intra-articular calcaneal fractures. We compared single-injection popliteal fossa blocks and continuous infusion popliteal fossa blocks with drug delivered through a catheter from an infusion pump (CPNB) to general or spinal anesthetic alone in terms of hospital charges, length of hospital stay, and postoperative oral and intravenous narcotic use, antiemetic use, and safety. Design: Retrospective review. Setting: University Level I regional trauma center and associated orthopaedic surgery center. Patients/Participants: Charts were reviewed for all patients undergoing open treatment of calcaneal fractures during a 9-year period. One hundred six of 203 met study inclusion criteria. Intervention: All patients received either general or spinal anesthetic. Patients additionally received preoperative single-injection popliteal fossa blocks, CPNB, or no regional block. Outcome Measurements: Data were compared from each group for total hospital cost, length of stay, operating room times, narcotic use, postoperative nausea, and hospital readmission. Eighteen patients from the CPNB group who were discharged within 24 hours of surgery were examined in a subgroup analysis of ambulatory treatment. Results: There were no significant differences between the control group and the two regional anesthesia groups in total hospital cost, length of stay, narcotic use, or antiemetic use. However, subgroup analysis demonstrated that ambulatory CPNB patients had significantly lower total hospital costs and narcotic use compared with the remaining CPNB patients. There were no block-related complications. None of the short-stay patients required urgent medical attention or readmission after discharge. Conclusions: CPNB through an infusion pump may allow patients undergoing open treatment of calcaneal fractures to be safely discharged within 24 hours with a concomitant decrease in healthcare costs. These data suggest that this method of postoperative pain management might be applied to other patients with major foot and ankle trauma and/or reconstructive procedures and that wider use of continuous peripheral nerve blocks may lead to a reduction in healthcare costs.