Alexandra K. Schwartz

Intramedullary Nailing of Distal Metaphyseal Tibial Fractures

BACKGROUND The treatment of distal metaphyseal tibial fractures remains controversial. This study was performed to evaluate the results of intramedullary nailing of distal tibial fractures located within 5 cm of the ankle joint. METHODS Over a sixteen-month period at two institutions, thirty-six tibial fractures that involved the distal 5 cm of the tibia were treated with reamed intramedullary nailing with use of either two or three distal interlocking screws. Ten fractures with articular extension were treated with supplementary screw fixation prior to the intramedullary nailing. Radiographs were reviewed to determine the immediate and final alignments and fracture-healing. The Short Form-36 (SF-36) and Musculoskeletal Function Assessment (MFA) questionnaires were used to evaluate functional outcome. RESULTS Acceptable radiographic alignment, defined as <5 degrees of angulation in any plane, was obtained in thirty-three patients (92%). No patient had any change in alignment between the immediate postoperative and the final radiographic evaluation. Complications included one deep infection and one iatrogenic fracture at the time of the intramedullary nailing. Six patients could not be followed. The remaining thirty fractures united at an average of 23.5 weeks. Three patients with associated traumatic bone loss underwent a staged autograft procedure, and they had fracture-healing at an average of 44.3 weeks. The functional outcome was determined at a minimum of one year for nineteen patients and at a minimum of two years (average, 4.5 years) for fifteen patients. At one year, there were significant limitations in several domains despite fracture union and maintenance of alignment, but there was improvement in the MFA scores with time. CONCLUSIONS Intramedullary nailing is an effective alternative for the treatment of distal metaphyseal tibial fractures. Simple articular extension of the fracture is not a contraindication to intramedullary fixation. Functional outcomes improve with time.

Biomechanical evaluation of clavicle fracture plating techniques: does a locking plate provide improved stability?

Objectives: To evaluate the biomechanical properties of both plate location (superior versus anterior-inferior) and plate type Small Fragment Contourable Dual Compression Plate (CDCP) versus 3.5 mm Universal Locking System Contourable Dual Compression Plate (Locked CDCP) in a synthetic midshaft transverse clavicle fracture model. Methods: Twenty-four pre-osteomized synthetic clavicles were repaired with either CDCP or locked CDCP technology 3.5 mm plates in either the superior or anterior-inferior position to form 4 groups of 6 clavicles. These were subsequently tested to evaluate torsional and axial construct stiffness, as well as bending load to failure, bending failure stiffness, and method of failure. Results: In axial compression, locked CDCP constructs were significantly more stiff than CDCP constructs (p < 0.001), but no statistically significant effect of plate location was observed. Torsional tests demonstrated a significant 2-way interaction favoring locked CDCP plates in the superior position and standard CDCP plates in the anterior-inferior position (p < 0.001). Bending failure testing revealed that the superior plate location had higher load to failure and bending failure stiffness than the anterior-inferior location (p < 0.0001). In addition, the superior locked CDCP plates demonstrated significantly greater bending failure stiffness than superior CDCP plates (p < 0.0001). Conclusions: Biomechanically, repairing a midshaft clavicle fracture with a superior plate was more favorable compared to anterior-inferior plating in terms of both load to failure and bending failure stiffness. Furthermore, superior locked CDCP plates show improved bending failure stiffness over superior CDCP plates.

Reconstruction plates for stabilization of mid-shaft clavicle fractures: Differences between nonlocked and locked plates in two different positions

Reconstruction plates permit contouring to the irregular anatomic shape of the clavicle. This study evaluated the biomechanical stability of locking and nonlocking clavicle reconstruction plates for treating midshaft, transverse fractures, comparing anterior-inferior to superior plate position. Twenty-four synthetic clavicles with mid-shaft fractures were repaired with either a locking or nonlocking clavicle reconstruction plate in either the anterior-inferior or superior plate position (n = 6/group). Repaired constructs were tested in axial compression, axial torsion, and cantilever bending failure. In compression, anterior-inferior plates were significantly stiffer than superior plates and locked plates stiffer than nonlocked. In torsion, anterior-inferior plates were stiffer, with a significant interaction term that favored anterior-inferior locked and superior nonlocked plates. In cantilever bending, superior plates had a significantly higher bending failure load and stiffness. Anterior-inferior plates failed at a significantly lower load ( approximately 40 N or approximately 4 kg), which could potentially occur in the postoperative period.

Combat versus civilian open tibia fractures: The effect of blast mechanism on limb salvage

BACKGROUND This study compares open tibia fractures in US Navy and US Marine Corps casualties from the current conflicts with those from a civilian Level I trauma center to analyze the effect of blast mechanism on limb-salvage rates. METHODS Data from the 28,646 records in the University of California San Diego Trauma Registry from 1985 to 2006 was compared with 2,282 records from the US Navy and US Marine Corps Combat Trauma Registry Expeditionary Medical Encounter Database for the period of March 2004 to August 2007. Injuries were categorized by Gustilo-Anderson (G-A) open fracture classification. Independent variables included age, gender, mechanism of injury including blast mechanisms, shock, blood loss, prehospital time, procedures, Injury Severity Score, length of stay, and Mangled Extremity Severity Score (MESS). Dependent variables included early or late amputation and mortality. RESULTS The civilian group had 850 open tibia fractures with 45 amputations; the military group had 21 amputation patients (3 bilateral) in 115 open tibia fractures. Military group patients were more severely injured, more likely have hypotension, and had a higher amputation rate for G-A IIIB and IIIC fractures then civilian group patients. Blast mechanism was seen in the majority of military group patients and was rare in the civilian group. MESS scores had poor sensitivity (0.46, 95% confidence interval: 0.29-0.64) in predicting the need for amputation in the civilian group; in the military group sensitivity was better (0.67, 95% confidence interval: 0.43-0.85), but successful limb salvage was still possible in most cases with an MESS score of ≥7 when attempted. CONCLUSION Despite current therapy, limb salvage for G-A IIIB and IIIC grades are significantly worse for open tibia fractures as a result of blast injury when compared with typical civilian mechanisms. MESS scores do not adequately predict likelihood of limb salvage in combat or civilian open tibia fractures.

Chondrocyte viability after intra-articular calcaneal fractures in humans

Background: Chondral damage from the impact of injury may contribute to the high incidence of post-traumatic arthritis after calcaneal fractures, but this has yet to be proven. We sought to study the effect of intra-articular calcaneal fractures on chondrocyte viability and to correlate these effects with injury severity, time from injury to surgery, and patient age and co-morbidities. Methods: Irreducible osteochondral fragments from 12 patients undergoing operative treatment for intra-articular calcaneal fractures were analyzed. Control cartilage was obtained from four tissue donors who died of unrelated causes. The cartilage was assessed for chondrocyte viability through the full thickness of tissue using a Live/Dead assay followed by laser scanning confocal microscopy. Patient demographics including injury classification and severity, time from injury to surgery, and patient age were recorded. Results: Chondrocyte viability from fracture patients averaged 72.8% ± 12.9% (range 53% to 95%), which was significantly lower than the 94.8% ± 1.5% viability observed in the control specimens (p = 0.005). Chondrocyte viability declined with higher energy injuries (p = 0.13), time from injury to surgery (p = 0.07), and increasing patient age (p = 0.07). However, none of these factors reached a level of statistical significance. Conclusions: A significant decline in chondrocyte viability occurs after intra-articular fractures of the calcaneus. This may contribute to the development of post-traumatic arthritis.

Lessons learned from the institution of the Surgical Care Improvement Project at a teaching medical center

BACKGROUND The Surgical Care Improvement Project (SCIP) was designed to reduce perioperative complications. We describe our institutional experience in 6 major areas: surgical site infection, venous thromboembolism prevention, use of perioperative beta-blockade, serum glucose level greater than 200 mg/dL, normothermia, and the use of electric razors for hair removal. METHODS This was a retrospective review of surgical cases. Evidence-based training and standardization of system and process were undertaken. Compliance with SCIP guidelines was determined. RESULTS Overall SCIP compliance improved from 80% to 94% over a 2-year period. Standardized antibiotic dosing times improved compliance to more than 90%. Appropriate preoperative antibiotic choice improved to 100%. Cessation of antibiotics postoperatively within 24 hours remains a difficult task. Venous thromboembolism prophylaxis has been difficult to achieve because of postoperative bleeding concerns. Administration of beta-blockers has remained one of the most difficult problems to correct because of the multiplicity of avenues by which a patient may arrive to the operating suite. CONCLUSIONS Achievement of the SCIP goals is a formidable, but achievable, process requiring individual, cultural, systems, and institutional changes to achieve success.

Noninvasive measurements of intramuscular pressure using pulsed phase-locked loop ultrasound for detecting compartment syndromes: a preliminary report.

Objectives To develop a human model for compartment tamponade and test the efficacy of ultrasonic pulsed phase-locked loop (PPLL) fascial displacement waveform analysis for noninvasive measurement of intramuscular pressure (IMP). Design Human subject experiment. Setting University Level 1 trauma center. Participants Nine male and 1 female volunteers (age 20 to 59),3 male acute compartment syndrome (ACS) patients (age 31 to 38). Intervention Thigh tourniquet was inflated in a stepwise fashion from 40 to 100 mm Hg to increase IMP transiently in volunteers. Main Outcome Measurements Invasive IMP by slit catheter and PPLL fascial displacement waveform in volunteers with model ACS and patients with ACS. Results In the model compartment tamponade group, thigh cuff occlusion increased IMP in the anterior compartment from a mean of 12.1 mm Hg (SE=1.5) to a mean of 27.4 mm Hg (SE=2.4, N=8, P<0.0001). By fast Fourier transform, the ratio of the amplitude of the fundamental frequency to the amplitude of the second harmonic frequency of the fascial displacement waveform as measured by PPLL increased from a resting mean of 1.12 (SE=0.07) to a mean of 1.85 (SE=0.18) under the same protocol (N=6, P=0.001). Combined data with compartment syndrome patients revealed linear correlation between IMP and PPLL with an R2 value of 0.8887. Conclusions Subarterial thigh cuff pressure causes a significant and transient increase in IMP, serving as a model for anterior compartment tamponade. PPLL is able to detect fascial displacement waveforms corresponding to arterial pulsation and furthermore distinguishes between normal and elevated IMP. There is a linear correlation between PPLL measurements and invasive IMP. The PPLL shows potential utility as a device for noninvasive measurement of IMP for detecting compartment syndromes.

Stiff muscle fibers in calf muscles of patients with cerebral palsy lead to high passive muscle stiffness

Cerebral palsy (CP), caused by an injury to the developing brain, can lead to alterations in muscle function. Subsequently, increased muscle stiffness and decreased joint range of motion are often seen in patients with CP. We examined mechanical and biochemical properties of the gastrocnemius and soleus muscles, which are involved in equinus muscle contracture. Passive mechanical testing of single muscle fibers from gastrocnemius and soleus muscle of patients with CP undergoing surgery for equinus deformity showed a significant increase in fiber stiffness (p < 0.01). Bundles of fibers that included their surrounding connective tissues showed no stiffness difference (p = 0.28).). When in vivo sarcomere lengths were measured and fiber and bundle stiffness compared at these lengths, both fibers and bundles of patients with CP were predicted to be much stiffer in vivo compared to typically developing (TD) individuals. Interestingly, differences in fiber and bundle stiffness were not explained by typical biochemical measures such as titin molecular weight (a giant protein thought to impact fiber stiffness) or collagen content (a proxy for extracellular matrix amount). We suggest that the passive mechanical properties of fibers and bundles are thus poorly understood.

Effect of Tibial Plateau Fracture on Lubrication Function and Composition of Synovial Fluid

BACKGROUND Intra-articular fractures may hasten posttraumatic arthritis in patients who are typically too active and too young for joint replacement. Current orthopaedic treatment principles, including recreating anatomic alignment and establishing articular congruity, have not eliminated posttraumatic arthritis. Additional biomechanical and biological factors may contribute to the development of arthritis. The objective of the present study was to evaluate human synovial fluid for friction-lowering function and the concentrations of putative lubricant molecules following tibial plateau fractures. METHODS Synovial fluid specimens were obtained from the knees of eight patients (twenty-five to fifty-seven years old) with a tibial plateau fracture, with five specimens from the injured knee as plateau fracture synovial fluid and six specimens from the contralateral knee as control synovial fluid. Each specimen was centrifuged to obtain a fluid sample, separated from a cell pellet, for further analysis. For each fluid sample, the start-up (static) and steady-state (kinetic) friction coefficients in the boundary mode of lubrication were determined from a cartilage-on-cartilage biomechanical test of friction. Also, concentrations of the putative lubricants, hyaluronan and proteoglycan-4, as well as total protein, were determined for fluid samples. RESULTS The group of experimental samples were obtained at a mean (and standard deviation) of 11 ± 9 days after injury from patients with a mean age of 45 ± 13 years. Start-up and kinetic friction coefficients demonstrated similar trends and dependencies. The kinetic friction coefficients for human plateau fracture synovial fluid were approximately 100% higher than those for control human synovial fluid. Hyaluronan concentrations were ninefold lower for plateau fracture synovial fluid compared with the control synovial fluid, whereas proteoglycan-4 concentrations were more than twofold higher in plateau fracture synovial fluid compared with the control synovial fluid. Univariate and multivariate regression analysis indicated that kinetic friction coefficient increased as hyaluronan concentration decreased. CONCLUSIONS Knees afflicted with a tibial plateau fracture have synovial fluid with decreased lubrication properties in association with a decreased concentration of hyaluronan.

Is bigger better? The effect of obesity on pelvic fractures after side impact motor vehicle crashes

BACKGROUND Previous research has identified nearside impacts, intrusion, gender, age, and body mass index (BMI) as associated with pelvic fractures in motor vehicle crashes. This study assesses the role of BMI in predicting pelvic fracture and whether BMI modifies the effect of other potential risk factors. METHODS The Crash Injury Research and Engineering Network data were queried to study occupant, vehicle, and crash factors predicting pelvic injury in occupants of nearside crashes. Occupants in different BMI categories were compared with assess odds of pelvic fracture during nearside impacts. Logistic regression was used to identify predictive variables for pelvic fracture controlling for age, gender, delta V, intrusion, side airbag deployment, seat position, vehicle curb weight, and safety belt use. RESULTS Two hundred forty-four (57.5%) occupants in nearside impacts sustained pelvic fractures. Occupants with a normal BMI were more likely (unadjusted odds ratio = 1.80, adjusted odds ratio = 1.98) to have a pelvis fracture compared with overweight and obese occupants. Door panel intrusion >15 cm, female gender, and delta V were associated with pelvic fracture in univariate analyses. BMI was a predictor of pelvic fracture when controlling for potential confounding factors. CONCLUSIONS BMI status influences other variables associated with pelvic fracture. Redesign of interior door panels, hardware, armrests, and the center console may be appropriate for motor vehicle manufacturers to consider in prevention of pelvic fracture during nearside impacts.