Effects of Degree of Surgical Correction for Flatfoot Deformity in Patient-Specific Computational Models.

A cohort of adult acquired flatfoot deformity rigid-body models was developed to investigate the effects of isolated tendon transfer with successive levels of medializing calcaneal osteotomy (MCO). Following IRB approval, six diagnosed flatfoot sufferers were subjected to magnetic resonance imaging (MRI) and their scans used to derive patient-specific models. Single-leg stance was modeled, constrained solely through physiologic joint contact, passive soft-tissue tension, extrinsic muscle force, body weight, and without assumptions of idealized mechanical joints. Surgical effect was quantified using simulated mediolateral (ML) and anteroposterior (AP) X-rays, pedobarography, soft-tissue strains, and joint contact force. Radiographic changes varied across states with the largest average improvements for the tendon transfer (TT) + 10 mm MCO state evidenced through ML and AP talo-1st metatarsal angles. Interestingly, 12 of 14 measures showed increased deformity following TT-only, though all increases disappeared with inclusion of MCO. Plantar force distributions showed medial forefoot offloading concomitant with increases laterally such that the most corrected state had 9.0% greater lateral load. Predicted alterations in spring, deltoid, and plantar fascia soft-tissue strain agreed with prior cadaveric and computational works suggesting decreased strain medially with successive surgical repair. Finally, joint contact force demonstrated consistent medial offloading concomitant with variable increases laterally. Rigid-body modeling thus offers novel advantages for the investigation of foot/ankle biomechanics not easily measured in vivo.

A population of patient-specific adult acquired flatfoot deformity models before and after surgery.

Following IRB approval, a cohort of 3-D rigid-body computational models was created from submillimeter MRIs of clinically diagnosed Adult Acquired Flatfoot Deformity patients and employed to investigate postoperative foot/ankle function and surgical effect during single-leg stance. Models were constrained through physiologic joint contact, passive soft-tissue tension, active muscle force, full body weight, and without idealized joints. Models were validated against patient-matched controls using clinically utilized radiographic angle and distance measures and plantar force distributions in the medial forefoot, lateral forefoot, and hindfoot. Each model further predicted changes in strain for the spring ligament, deltoid ligament, and plantar fascia, as well as joint contact loads for three midfoot joints, the talonavicular, navicular-1st cuneiform, and calcaneocuboid. Radiographic agreement ranged across measures, with average absolute deviations of <5° and <4 mm indicating generally good agreement. Postoperative plantar force loading in patients and models was reduced for the medial forefoot and hindfoot concomitant with increases in the lateral forefoot. Model predicted reductions in medial soft-tissue strain and increases in lateral joint contact load were consistent with in vitro observations and elucidate the biomechanical mechanisms of repair. Thus, validated rigid-body models offer promise for the investigation of foot/ankle kinematics and biomechanical behaviors that are difficult to measure in vivo.

The successful use of vancomycin-impregnated cement beads in a patient with vancomycin systemic toxicity: a case report with review of literature.

We report the use of vancomycin laden antibiotic cement beads in a patient with calcaneal osteomyelitis who had prior acute kidney injury (AKI). The patient experienced non-oliguric renal failure after exposure to intravenous vancomycin and recovered well after antibiotic discontinuation and adequate hydration. We are not aware of any similar case report where vancomycin laden antibiotic cement has been used in a patient with AKI to vancomycin.

Complications of forefoot and midfoot fractures.

Complications of the forefoot and midfoot are not as common as injuries to the hindfoot. The problem areas that the author will focus on with these injuries will be open injuries, unstable fractures, slow or poor healing fractures, and neurovascular injuries. The author also will discuss the toes, metatarsals, tarsometatarsal, cuneiforms, and talonavicular areas. Because the forefoot and midfoot must support as much as four times the body weight, alterations caused by injury to the weightbearing surface can have significant consequences. Treatment rationale to maintain a sound weightbearing plantar surface will be discussed. Each region will be highlighted with respect to the complications that can occur. Anatomic alignment with stable fixation and good soft tissue coverage in an appropriate rehabilitation program are the principles that should be followed and discussed.

Biomechanical comparison of ankle arthrodesis techniques: crossed screws vs. blade plate.

Many different techniques for ankle arthrodesis have been described. Experience at our institution with crossed screws internal fixation has not met the 90+% union rate reported in the literature. A compression blade plate is one technique for ankle arthrodesis which has not been evaluated biomechanically. A biomechanical study comparing two groups of sawbone ankle fusion constructs fixed with crossed screws and compression blade plates was performed in order to evaluate the stiffness and rigidity of these two arthrodesis techniques. The crossed screws construct demonstrated superior stiffness during dorsiflexion (p < 0.001) and valgus (p < 0.001) loading. The two constructs were found to have equal strength in resisting plantarflexion, varus and torsional loads although there was a trend for greater resistance by the crossed screws construct. These findings lend biomechanical support to the use of crossed screws for tibiotalar arthrodesis.

Adhesive capsulitis of the shoulder in male cardiac surgery patients.

Two hundred fourteen consecutive male cardiac surgery patients were retrospectively evaluated for the incidence of adhesive capsulitis of the shoulder and were assessed for risk factors. Only male patients were included, as the study took place at a Veteran's hospital. Patients who had no shoulder problems prior to cardiac surgery and were experiencing shoulder pain or stiffness postoperatively underwent history, physical examination, and radiographic studies. Thirty-five patients who had shoulder complaints were identified and evaluated. A 3.3% incidence (seven patients) of adhesive capsulitis of the shoulder in a male post-cardiac surgery population was established.

Comparison of two proximal osteotomies for the treatment of hallux valgus.

Moderate to severe deformities of hallux valgus can be corrected with combination procedures, such as a proximal crescentic metatarsal osteotomy and a distal soft tissue procedure. Because crescentic osteotomy allows for motion in all planes, inadvertent metatarsal elevation can result in metatarsalgia. The crescentic shelf osteotomy (CSO) provides a plantar shelf, decreasing the complication of dorsiflexion fixation. Eighteen polyurethane foam specimens in three groups were prepared and tested to failure on a servohydraulic Instron testing machine. The mechanical characteristics of stiffness, deformation, ultimate failure load, and stored energy were compared between single-screw fixation crescentic osteotomies and single- and dual-screw CSOs in molded polyurethane foam metatarsal sawbones. In addition, 12 cadaver specimens were randomly divided, and a CSO or crescentic osteotomy was performed. Preosteotomy and postosteotomy intermetatarsal, dorsiflexion, and pronation angles were compared from radiograph measurements. The results showed comparable mechanical characteristics among the groups, as measured by the area under the curve (P=0.95), ultimate failure load (P=0.35), deformation (P=0.63), and stiffness (P=0.21). Greater improvements were seen in the CSO group compared with the crescentic osteotomy group in correction of the intermetatarsal angle (4.8 degrees compared with 3.2 degrees) and of the first metatarsal plantarflexion (2.3 degrees compared with 3.2 degrees of dorsiflexion). However, these differences were insignificant (P=0.10 and P=0.41) with the numbers available. Compared with the crescentic osteotomy, a CSO may possibly provide easier initial fixation but similar mechanical properties.

Elongation behavior of calcaneofibular and cervical ligaments during inversion loads applied in an open kinetic chain.

The cervical ligament plays a significant role in lateral stability of the subtalar joint but has received little attention compared with other ankle and subtalar joint ligaments. The purpose of this research was twofold. First, the elongation behavior of the cervical ligament was assessed with the calcaneofibular ligament intact and cut during two different types of inversion loads (manual and mechanical). Second, inversion range of motion was determined concomitantly with inversion loading and the difference in inversion range of motion between the calcaneofibular ligament intact to cut state was compared. The mean elongation of the cervical ligament with the calcaneofibular intact was 0.58 mm (+/- 0.33 mm) and 0.46 mm (+/- 0.23 mm) for manual and mechanical methods, respectively, and 0.88 mm (+/- 0.37 mm) and 0.78 mm (+/- 0.37 mm), respectively, for the same methods in the absence of the calcaneofibular ligament. This difference was statistically significant (P < 0.05 manually and P < 0.02 mechanically). An average increase in the inversion range of motion was noted with both methods [7.5 degrees manually (+/- 2.75 degrees) and 7.7 degrees mechanically (+/- 2.95 degrees)] after lesioning of the calcaneofibular ligament. This difference was statistically significant (P < 0.001) for both manual and mechanical range of motion testing. The results of this study indicate that there is a significant increase in elongation of the cervical ligament in the absence of the calcaneofibular ligament during manual and mechanically applied inversion loads in a open kinetic chain. Clinical and theoretical implications of this data are discussed.

Complex fractures of the talus.

Injuries of the talus make up a significant proportion of complex foot and ankle injuries. The severity of these injuries is increasing because the availability and use of better safety equipment has allowed more people to survive serious accidents. Early rigid and accurate anatomic fixation lead to the best possible outcome for each category of talar injury. If osteonecrosis is suspected, titanium screws should be used for fixation to allow better postoperative follow-up. Treatment of osteonecrosis of the talus still depends mainly on clinical judgment, with the MRI providing more clinical data. The outcome of the osteonecrotic talus has not been established at this point. The approach to the talus depends on the judgment and skill of the surgeon; two approaches usually are indicated for more severe injuries. A CT scan is quite helpful for fractures of the talar body; preoperative planning and the judicious use of malleolar osteotomy with preservation of the deltoid artery are advocated. Tibiotalar and talocalcaneal motion have been altered as a result of talar fractures. Arthrosis of the subtalar joint depends on the degree of injury.

The effect of tibiotalar fixation on foot biomechanics.

Contact areas and peak pressures in the posterior facet of the subtalar and the talonavicular joints were measured in cadaver lower limbs for both the normal limb and after fixation of the tibiotalar joint. Six joints were fixed in neutral, in 5-7 degrees of varus and of valgus. Ten degrees of equinus angulation was also studied. Each position of fixation was tested independently. Neutral was defined as fixation without coronal or sagittal plane angulation compared with prefixation alignment of the specimen. When compared with normal unfused condition, peak pressures increased, and contact areas decreased in the subtalar joint for specimens fixed in neutral, varus, and valgus. However, the change in peak pressure for neutral fusion compared with normal control was not statistically significant (P > 0.07). Peak pressures for varus and valgus fixation were significantly different from normal (P < 0.001). Contact areas for all positions of fixation were significantly different from normal (P < 0.001). Coronal plane angulation, however, also resulted in significantly lower contact areas compared with neutral fixation (P < 0.001). Contact areas and peak pressures in the talonavicular joint did not appear to be substantially affected by tibiotalar fixation with coronal plane angulation. Equinus fixation qualitatively increased contact areas and peak pressures in the talonavicular and posterior facet of the subtalar joint. Neutral alignment of the tibiotalar joint in the coronal and sagittal planes altered subtalar and talonavicular joint contact characteristics the least compared with normal controls. Therefore, ankle fusion in the neutral position would be expected to most closely preserve normal joint biomechanics and may limit the progression of degenerative arthrosis of the subtalar joint.

Contribution of the deltoid ligament to ankle joint contact characteristics: a cadaver study.

Changes in ankle biomechanics lead to altered load transmission through the ankle joint, possibly predisposing it to osteoarthritis. Contributions of the different bands of the deltoid ligament to the contact characteristics in the ankle were examined. Fifteen normal cadaveric lower extremities were axially loaded to 445 N after intra-articular Fuji film placement. Ankles were tested in neutral, 10 degrees dorsiflexion, and 10 degrees plantarflexion. Repeated testing was done following sequential sectioning of the deltoid ligament, and the contact characteristics were analyzed. The greatest significant tibiotalar changes (P < 0.0001) occurred after sectioning of the tibiocalcaneal fibers of the superficial deltoid ligament complex. Contact areas decreased up to 43%, peak pressures increased up to 30%, and centroids moved 4 mm laterally, on average. In contrast, sectioning of the other bands led to insignificant changes in joint contact characteristics. The data indicate that significant changes in contact characteristics occur before radiographic evidence of deltoid ligament damage is evident, and may indicate that greater attention to the medial side of the ankle is indicated to restore normal biomechanics to this joint.

Clinical rating systems for the ankle-hindfoot, midfoot, hallux, and lesser toes.

Four rating systems were developed by the American Orthopaedic Foot and Ankle Society to provide a standard method of reporting clinical status of the ankle and foot. The systems incorporate both subjective and objective factors into numerical scales to describe function, alignment, and pain.

Symptomatic lumbar stenosis following fusion using sublaminar hooks. Case report.

A case of postfusion lumbar stenosis caused by the presence of sublaminar hooks is described. The patient was a 52-year-old man who 11 years previously had undergone lumbar fusion with Harrington rod instrumentation for a traumatic L-2 vertebral body fracture. Postoperatively, he developed progressive low-back pain, neurogenic claudication, and significant lower-extremity weakness and atrophy. Upon radiological examination, he was found to have high-grade lumbar stenosis at the level of the caudal sublaminar hooks. The instrumentation was removed and the area of radiological stenosis decompressed. Clinically, both the patient's pain and motor deficits resolved and, on postoperative imaging, the stenosis was relieved. Thus, despite other areas of persisting pathology, it is concluded that the stenosis occurring at the level of the caudal sublaminar hooks contributed to the patient's symptoms. Although not a common cause of postfusion stenosis, the presence of instrumentation in the proximity of neural elements must be considered as an etiology for neurological dysfunction.

Tibiotalar joint dynamics: indications for the syndesmotic screw--a cadaver study.

Pronation-external rotation ankle injuries involve varying degrees of disruption of the syndesmotic ligaments. The loss of ligament support and alteration in the stability of the mortise have been postulated to lead to an increase in joint reactive forces and traumatic arthritis. The purpose of this study was to determine the changes in tibiotalar joint dynamics associated with syndesmotic diastasis as a result of the sequential sectioning of the syndesmotic ligaments to simulate a pronation-external rotation injury. Dissections were conducted on 10 fresh-frozen, knee-disarticulated cadaveric specimens which were then axially loaded in an unconstrained manner. Tibiotalar joint forces were measured at each level of sequential sectioning of the syndesmotic ligaments, the interosseous membrane, and finally the deltoid ligament. Complete disruption of the syndesmosis with the medical structures of the ankle intact resulted in an average syndesmotic widening of 0.24 mm and no significant change in the tibiotalar contact area or the peak pressure. However, deltoid ligament strain increases with sectioning of the syndesmosis. With the addition of deltoid ligament sectioning, there was an average syndesmotic diastasis of 0.73 mm, a 39% reduction in the tibiotalar contact area, and a 42% increase in the peak pressure. In a simulated unconstrained cadaveric model of a pronation-external rotation ankle injury that results in complete disruption of the syndesmosis, if rigid anatomic medial and lateral joint fixation is obtained and the deltoid ligament complex is intact, syndesmotic screw fixation is not required to maintain the integrity of the tibiotalar joint.

Effect of isolated talocalcaneal fusion on contact in the ankle and talonavicular joints.

A cadaveric model was developed to establish the articular contact area and load distribution in the ankle joint, posterior facet of the talocalcaneal joint, and talonavicular joint using pressure sensitive film. Positions of dorsiflexion, neutral, and plantarflexion were evaluated. This model was further used to determine the effect of talocalcaneal fusion on the articular contact area in the talonavicular and ankle joints. Alteration of articular contact was most pronounced in the talonavicular joint. There, a statistically significant reduction in contact area postfusion was noted when the foot was in the plantarflexed position. Reductions in ankle joint articular contact area were observed in the dorsiflexed and plantarflexed positions in the majority of specimens. Lateral displacement of the region of articular contact was noted in some specimens. A pressure-weighted centroid calculation was performed to provide a quantitative measure of the shift of the contact region.

A comparison of the Brooker-Wills and Russell-Taylor nails for treatment of patients who have fractures of the femoral shaft.

Seventy-three fractures of the femoral shaft (seventy patients) were randomized to treatment with interlocked nailing with either the Brooker-Wills femoral nail (thirty-nine fractures) or the Russell-Taylor femoral nail (thirty-four fractures). Sixty-one patients (sixty-four fractures) were prospectively followed from admission until healing of the fracture. Specific attention was paid to recording operative details, including technical difficulties associated with insertion of the nails. Technical difficulties were encountered in insertion of the proximal screw, distal screw, and nail, and in deployment of the fins. Insertion of the Russell-Taylor nail was associated with less technical difficulty, operative time, and estimated loss of blood. The two nails differ in their biomechanical properties, methods of fixation, and instrumentation. These differences did not affect the clinical outcome; the fractures in both groups of patients healed with excellent functional results.

The treatment of complex fractures of the talus.

The treatment of complex talar injuries entails an intricate knowledge of the anatomy and blood supply to the talus. The approach used should not violate any vascular structure, and the fixation used should be biomechanically stable to allow fracture healing. The three classes of talar fractures are discussed as well as avascular necrosis, talar salvage problems, and talar body fractures.