Aaron T. Scott

Vascular injury associated with extremity trauma: initial diagnosis and management.

Abstract Vascular injury associated with extremity trauma occurs in <1% of patients with long bone fracture, although vascular injury may be seen in up to 16% of patients with knee dislocation. In the absence of obvious signs of vascular compromise, limb‐threatening injuries are easily missed, with potentially devastating consequences. A thorough vascular assessment is essential; an arterial pressure index <0.90 is indicative of potential vascular compromise. Advances in CT and duplex ultrasonography are sensitive and specific in screening for vascular injury. Communication between the orthopaedic surgeon and the vascular or general trauma surgeon is essential in determining whether to address the vascular lesion or the orthopaedic injury first. Quality evidence regarding the optimal fixation method is scarce. Open vascular repair, such as direct repair with or without arteriorrhaphy, interposition replacement, and bypass graft with an autologous vein or polytetrafluoroethylene, remains the standard of care in managing vascular injury associated with extremity trauma. Although surgical technique affects outcome, results are primarily dependent on early detection of vascular injury followed by immediate treatment.

Plantar pressure analysis in cadaver feet after bony procedures commonly used in the treatment of stage II posterior tibial tendon insufficiency.

Background: Bony procedures play an essential role in the operative treatment of stage II posterior tibial tendon insufficiency and often substantially alter the loading characteristics of the foot. Methods: Eight matched pairs of cadaver lower extremities were axially loaded onto a TekScan HR Mat. (TekScan, Inc., South Boston, MA) After intact testing, each specimen had a lateral column lengthening (either a calcaneocuboid distraction arthrodesis [CCDA] or Evans procedure), a medializing calcaneal osteotomy (MCO), and a plantarflexion (Cotton) osteotomy of the medial cuneiform. The measured plantar pressures were divided into three forefoot regions, two midfoot regions, and two hindfoot regions. For each region, average pressure, peak pressure, and contact area data were collected. Results: Despite the fact that both lateral column lengthening procedures resulted in increased lateral forefoot pressures, no significant differences were noted between the CCDA and the Evans procedure. The addition of a MCO did not significantly alter the plantar pressures measured after the lateral column lengthening alone. Although the Cotton osteotomy resulted in increased average pressures within the medial forefoot, a compensatory significant decrease in lateral forefoot pressures was not observed. Conclusions: The present study demonstrated increased lateral forefoot pressures after a combined lateral column lengthening and MCO and does not support the idea that a Cotton osteotomy significantly reduces loading of the lateral forefoot. Clinical Relevance: The incidence of lateral forefoot pain and fifth metatarsal stress fractures subsequent to either lateral column lengthening procedure may not significantly decline after a Cotton osteotomy.

Fusion versus excision of the symptomatic Type II accessory navicular: a prospective study.

Background: Patients with symptomatic Type II accessory naviculars that fail nonoperative measures may be treated with excision, percutaneous drilling, a modified Kidner procedure, or a fourth option, arthrodesis of the accessory ossicle to the navicular body. There is little information in the literature on the relative merits of arthrodesis. Materials and Methods: A prospective evaluation of 20 patients undergoing surgical intervention for symptomatic Type II accessory naviculars was performed. The decision to perform either an arthrodesis (10 feet) or a modified Kidner (10 feet) was made intraoperatively based on the size of the accessory ossicle. Outcomes were measured using pre- and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot scores, plain radiographs, and chart reviews. Results: At an average followup of 35 months, the mean AOFAS score for the arthrodesis group improved from 50 to 93 points. There were two non-unions (20%) and one patient complained of painful hardware. At an average followup of 48 months, the mean AOFAS score for the modified Kidner group improved from 52 to 80 points. However, in this group, three of ten patients (30%) had persistent midfoot pain and radiographic evidence of progressive loss of the longitudinal arch. Conclusion: Although the methods do not represent a randomized comparison of treatments for the same condition, the results suggest that arthrodesis may be a reasonable treatment option in selected cases of patients with symptomatic recalcitrant Type II accessory naviculars that are large enough to accept small fragment screws. Level of Evidence: III, Retrospective Case Control Study

Biomechanical comparison of hallux valgus correction using the proximal chevron osteotomy fixed with a medial locking plate and the Ludloff osteotomy fixed with two screws

BACKGROUND For moderate-to-severe hallux valgus deformities with a 1-2 intermetatarsal angle in excess of 15 degrees , a proximal first metatarsal osteotomy is indicated. The ideal osteotomy has yet to be defined, but should inherently limit the incidence of dorsal malunion and allow for early ambulation. The present study evaluates the mechanical integrity of two popular first metatarsal osteotomies. METHODS Ten matched pairs of fresh-frozen cadaveric first metatarsals were harvested. In one metatarsal from each pair, a Ludloff osteotomy was created and fixed with two cannulated 3.5mm screws. In the contralateral first metatarsal, a proximal chevron osteotomy was performed and subsequently fixed with a medially applied locking plate. All specimens were mounted within an Instron 1321 servohydraulic materials testing machine and subjected to a plantar-to-dorsal cantilever bending protocol for 1000 cycles. FINDINGS Two of ten Ludloff osteotomies failed prior to completion of 1000 loading cycles by fracture at the distal screw site, whereas six of ten proximal chevrons failed prior to the 1000th cycle. The mode of failure in this group was by cut-out of the plantar-proximal screw. The bending stiffness of the Ludloff osteotomy exceeded that of the proximal chevron at all measurement points between the 1st and 200th load cycles (P<0.05). After 200 cycles, an inadequate number of plate constructs survived to allow statistical comparison. INTERPRETATION The results of the present study indicate that the proximal chevron osteotomy fixed with a medially based locking plate exhibits mechanical properties inferior to those of the Ludloff osteotomy under the tested conditions.

Normal aging alters in vivo passive biomechanical response of the rat gastrocnemius-Achilles muscle-tendon unit

Predisposition to Achilles tendon (AT) ruptures in middle-aged individuals may be associated with age-related changes to inherent passive biomechanical properties of the gastrocnemius-Achilles (GC-AT) muscle-tendon unit, due to known muscle-tendon structural changes in normal aging. The goal of this study was to determine whether the passive biomechanical response of the GC-AT muscle-tendon unit was altered with age in 6 young (8 months) and 6 middle-aged (24 months) F344xBN hybrid rats from the National Institute on Aging colony. Fungs quasilinear viscoelastic (QLV) model was used to determine in vivo history and time-dependent load-relaxation response of the GC-AT. Effective stiffness and modulus were also estimated using linear regression analysis. Fungs QLV revealed a significantly decreased magnitude of the relaxation response (parameter C, p=0.026) in middle-aged animals compared to young animals (0.108±0.007 vs. 0.144±0.015), with similar time-dependent viscous GC-AT properties (τ(1), τ(2)). The product of elastic parameters (A*B), which represents the initial slope of the elastic response, was significantly increased by 50% in middle-aged rats (p=0.014). Estimated GC-AT stiffness increased 28% at peak tensions in middle-aged rats (2.7±0.2 N/mm) compared to young rats (1.9±0.2 N/mm; p=0.036). While the limitations of this animal model must be considered, the changes we describe could be associated with the observation that GC-AT pathology and injury is more common in middle-aged individuals. Further studies are necessary to characterize the load-to-failure behavior of AT in middle-aged compared to young animals.

Single-row versus double-row repair of the distal Achilles tendon: a biomechanical comparison.

Surgery for recalcitrant insertional Achilles tendinopathy often consists of partial or total release of the insertion site, debridement of the diseased portion of the tendon, calcaneal ostectomy, and reattachment of the Achilles to the calcaneus. Although single-row and double-row techniques exist for repair of the detached Achilles tendon, biomechanical data are lacking to support one technique over the other. Based on data extrapolated from the study of rotator cuff repairs, we hypothesized that a double-row construct would provide superior fixation strength over a single-row repair. Eighteen human cadaveric Achilles tendons (9 matched pairs) with attached calcanei were repaired with single-row or double-row techniques. Specimens were mounted in a servohydraulic materials testing machine, subjected to a preconditioning cycle, and loaded to failure. Failure was defined as suture breakage or pullout, midsubstance tendon rupture, or anchor pullout. Among the failures were 12 suture failures, 5 proximal-row anchor failures, and 1 distal-row anchor failure. No midsubstance tendon ruptures or testing apparatus failures were observed. There were no statistically significant differences in the peak load to failure between the single-row and double-row repairs (p = .46). Similarly, no significant differences were observed with regards to mean energy expenditure to failure (p = .069). The present study demonstrated no biomechanical advantages of the double-row repair over a single-row repair. Despite the lack of a clear biomechanical advantage, there may exist clinical advantages of a double-row repair, such as reduction in knot prominence and restoration of the Achilles footprint.

Radiographic and CT Assessment of Reduction of Calcaneus Fractures Using a Limited Sinus Tarsi Incision

Background: The lateral extensile incision for fixation of displaced intra-articular calcaneus fractures allows for fracture reduction but has been associated with high rates of soft tissue complications. This has prompted a search for less invasive methods of fracture fixation. The purpose of the present study was to determine the adequacy of reduction and rate of complications associated with operative fixation of calcaneal fractures using a limited sinus tarsi approach. Methods: A limited sinus tarsi incision with plate fixation was utilized for treatment of 39 displaced intra-articular calcaneal fractures in 35 consecutive patients as part of a single surgeon series. Imaging assessment of previously described fracture displacement measures was undertaken in preoperative and postoperative radiographs and CT. A retrospective chart review was conducted to identify postoperative complications. Results: Mean preoperative Bohler angle measurement was 7.7 (range, –26.0 to 30.0) degrees and the mean final postoperative standing Bohler angle was 25.5 (range, 12.3 to 37.7) degrees. Postoperative CT demonstrated that subtalar articular reduction was within 2 mm of anatomic in 91% of patients. There were 2 instances of superficial wound dehiscence (5.1%) and 1 deep infection (2.6%) that required debridement and complete hardware removal. Visual analog score (VAS) for pain averaged 3 of 10 in the 32 available patients at 1-year follow-up. Eight of these patients (25%) reported no pain (0/10) at final follow-up. Conclusion: Operative fixation of displaced intra-articular calcaneal fractures utilizing the limited sinus tarsi approach resulted in acceptable fracture reduction and a low rate of complications. Level of Evidence: Level IV, retrospective case series.

Distal locking using an electromagnetic field-guided computer-based real-time system for orthopaedic trauma patients

Objectives: To compare the efficacy of distal interlocking during intramedullary nailing using a freehand technique versus an electromagnetic field real-time system (EFRTS). Design: A prospective, randomized controlled trial. Setting: Level I academic trauma center. Patients/Participants: Patients older than 18 years who sustained a femoral or tibial shaft fracture amenable to antegrade intramedullary nailing were prospectively enrolled between August 2010 and November 2011. Exclusion criteria included injuries requiring retrograde nailing and open wounds near the location of the distal interlocks (distal third of the femur, knee, or distal tibia). Intervention: Each patient had 2 distal interlocking screws placed: one using the freehand method and the other using EFRTS. Main Outcome Measurement: Techniques were compared on procedural time and number of interlocking screw misses. Two time points were measured: time 1 (time to find perfect circles/time from wand placement to drill initiation) and time 2 (drill initiation until completion of interlocking placement). Results: Twenty-four tibia and 24 femur fractures were studied. EFRTS proved faster at times 1 and 2 (P < 0.0001 and P < 0.0002) and total time (P < 0.0001). This difference was larger for junior residents, though reached statistical significance for senior residents. Senior residents were faster with the freehand technique compared with junior residents (P < 0.004), but the 2 were similar using EFRTS (P = 0.41). The number of misses was higher with free hand compared with EFRTS (P = 0.02). Conclusion: These results suggest that EFRTS is faster than the traditional freehand technique and results in fewer screw misses. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Polyethylene Fracture following STAR Ankle Arthroplasty: A Report of Three Cases

Level of Evidence: V, Case Report

External fixation in the treatment of tibial pilon fractures: comparison of two frames in torsion.

Background Ankle spanning external fixation has become the initial treatment of choice for complex tibial pilon fractures. Many fixator designs exist, but their biomechanical performance has not been studied extensively for this application. The goal of the present study was to compare the torsional performance of two commercially available frames, the Orthofix XCaliber and the Howmedica Hoffmann® II. Methods The XCaliber and the Hoffmann® II were each applied to six fresh cadaver lower extremities and were loaded in a materials testing machine. Strain gauges were attached to the anteromedial cortex of the distal tibia, and each specimen underwent torsional and axial load testing, with and without the external fixator. A simulated pilon fracture was created, and torsional testing was repeated. Results Results indicated that the XCaliber was significantly more rigid in internal rotation than the Hoffmann® II, before (49%) and after (41%) creation of the pilon fracture. Despite the XCalibers increased rigidity relative to the Hoffmann® II (22% to 31%) in external rotation, statistical significance was not attained. Both fixators reduced strain (25% to 85%) at the anteromedial cortex upon torsional testing, but no significant differences between the two frames were noted. Conclusions The present study demonstrates that the XCaliber has mechanical advantages over the Hoffmann® II in terms of torsional rigidity for a tibial pilon fracture. Clinical Relevance Increased rigidity of the XCaliber could potentially lead to decreased time to union, and a lower incidence of pin loosening and would prove beneficial in a setting in which the external fixator is used as the definitive fixation.