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Ligamentous Lisfranc injuries cause debilitating pain and loss of function. Even small diastasis of this normally rigid joint after injury requires surgical treatment, but outcomes remain poor. Existing literature has compared the different surgical procedures using cadaveric models, but no approach has been recommended over others. This study uses a computational biomechanical approach consistent with a cadaveric study to evaluate the different procedures' ability to stabilize the Lisfranc joint without inducing secondary consequences. A validated rigid body model for the cadaver foot with a Lisfranc injury was extended to compare the stability of four different surgical repairs-three open reduction and internal fixation procedures with different hardware (cannulated screws, endobuttons, and screws with a dorsal plate) and primary arthrodesis with screws. Forces calculated from the rigid body model for 50% partial weight bearing provided boundary conditions for a finite element model of the surgical repairs. Comparing the different surgical procedures, the open reduction and internal fixation with screws and primary arthrodesis with screws showed the most stable postoperative Lisfranc joint. However, the use of cannulated screws for fixation showed regions of high stress that may be susceptible to breakage and also resulted in higher contact forces in joints adjacent to the surgery site. Endobuttons and dorsal plates did not restore sufficient stability. Since all procedures showed different points of concern that could impact outcomes, additional surgical approaches could be needed in the future. This study offers a standard protocol for benchmarking the new procedures against those currently used. Published version

Several surgically corrective procedures are considered to treat Adult Acquired Flatfoot Deformity (AAFD) patients, relieve pain, and restore function. Procedure selection is based on best practices and surgeon preference. Recent research created patient specific models of AAFD to explore their predictive capabilities and examine effectiveness of the surgical procedure used to treat the deformity. The models' behavior was governed solely by patient bodyweight, soft tissue constraints, muscle loading, and joint contact without the assumption of idealized joints. The current work expanded those models to determine if an alternate procedure would be more effective for the individual. All procedures incorporated first a tendon transfer and then included one hindfoot procedure, the Medializing Calcaneal Osteotomy (MCO), and one of three lateral column procedures: Evans osteotomy, Calcaneocuboid Distraction Arthrodesis (CCDA), Z osteotomy, and the combination procedures MCO & Evans osteotomy, MCO & CCDA, and MCO & Z osteotomy. The combination MCO & Evans and MCO & Z procedures were shown to provide the greatest amount of correction for both forefoot abduction and hindfoot valgus. However, these two procedures significantly increased joint contact force, specifically at the calcaneocuboid joint, and ground reaction force along the lateral column. With exception to the lateral bands of the plantar fascia and middle spring ligament, the strain present in the plantar fascia, spring, and deltoid ligaments decreased after all procedures. The use of patient specific computational models provided the ability to investigate effects of alternate surgical corrections on restoring biomechanical function in these flatfoot patients. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1523-1531, 2017.

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.

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

Adult acquired flatfoot deformity (AAFD) is a degenerative disease resulting in malalignment of the mid- and hindfoot secondary to posterior tibial tendon dysfunction and increasing implication of ligament pathologies. Despite the complex 3D nature of AAFD, 2D radiographs are still employed to diagnose and stage the disease. Computer modeling techniques allow for accurate 3D recreations of musculoskeletal systems for the investigation of biomechanical factors contributing to disease. Following Institutional Review Board approval, the lower limbs of six diagnosed AAFD sufferers were imaged with MRI, photographs, and X-ray. Next, a radiologist graded the MRI attenuation of eight soft-tissues implicated in AAFD. Six patient-specific rigid-body models were then created and loaded according to patient weight, graded soft-tissues, and extrinsic muscles. Model function was validated using clinically relevant kinematic measures in three planes. Agreement varied depending on the measure, with average absolute deviations of

Background: Flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendon transfers are frequently used to restore the function of a deficient tibialis posterior tendon in stage II adult acquired flatfoot deformity (AAFD). Either transfer causes some loss in toe flexion force, although the decision to tenodese the cut tendon to restore associated function remains controversial. This study quantified changes in plantar force before and after tendon transfer and with or without distal tenodesis in a cadaveric model. Methods: The plantar force distribution of 10 matched pairs of statically loaded cadaveric lower extremities was investigated. Each foot was tested when it was intact, after FDL/FHL tendon transfer, and after tendon transfer + tenodesis. Results: Transfer of either FHL or FDL showed a statistically significant decrease in flexion force of the great toe ( P < .01) and lesser toes ( P < .001), respectively. Subsequent tenodesis in either tendon demonstrated an ability to restore flexion force in the great ( P < .05) and lesser ( P < .01) toes, respectively, with the FHL transfer + tenodesis restoring great toe loading to near pretransfer levels. Following either transfer, plantar force increased in the medial forefoot; this was sustained with FDL transfer + tenodesis but reduced under FHL transfer + tenodesis. Lateral forefoot force increased modestly (8%) with FHL transfer ( P < .05) but returned to near intact levels with tenodesis. FDL transfer + tenodesis resulted in increased medial midfoot and heel loading. Discussion: FHL or FDL transfer notably reduces associated toe flexion force. This loss can be restored to near normal levels with tenodesis for FHL transfer. As increased lateral forefoot loading is commonly associated with AAFD corrective procedures, FHL tenodesis may mitigate the unintended increases caused by the tendon transfer. The medial midfoot and heel loading with FDL transfer + tenodesis underscores that tendon transfers alone do not reestablish the passive architecture of the foot but augment deficient subtalar inversion force. Clinical Relevance: This cadaveric study shows that the FHL is more biomechanically suitable for tibialis posterior tendon insufficiency than the FDL, which may be a basis for a study to investigate whether it is superior in a clinical situation.

Background: Displaced medial malleolus fractures require surgical repair because of the critical role the structure plays in normal joint function. Various approaches exist, but options are limited for small fragment fractures. This study compared repair with the Medial Malleolar Sled fixation system (Trimed, Inc, Valencia, CA) to lag screws in 2 modes of biomechanical loading in a cadaveric model. Methods: A Müller type B medial malleolus fracture was simulated on matched pairs of cadaveric lower extremities and repaired with the sled or 2 cancellous lag screws. Tibial distraction (tension, n = 10) or internal rotation (torsion, n = 11) was applied. Fragment movement was measured in the sagittal (tension and torsion) and transverse (torsion-only) planes. Fragment movement at 1 mm and 2 mm (clinical malunion) of gapping during tension and at 2, 4, 6, and 8 N-m during torsion was analyzed via paired t tests. Results: In tension, the load at the 2-mm gap was statistically lower for screws ( P = .026). Opening angle was statistically larger for the sled at the 1-mm ( P = .0004) and 2-mm ( P = .008) gap. In torsion, gapping was statistically lower for the sled (ranging from P = .0013 at 4 N-m to P = .0187 at 8 N-m). No differences were detected for opening angle or transverse plane movement. Conclusion: The sled appeared stronger in tension and as effective as lag screws in torsion. The sled may be a viable option for fractures too small for 4.0- or 3.5-mm lag screws. Clinical Relevance: The sled may be suitable in applications where a tension band would normally be considered and may provide stronger fixation in osteoporotic bone compared with lag screw fixation.

Several surgically corrective procedures are considered to treat Adult Acquired Flatfoot Deformity (AAFD) patients, relieve pain, and restore function. Procedure selection is based on best practices and surgeon preference. Recent research created patient specific models of AAFD to explore their predictive capabilities and examine effectiveness of the surgical procedure used to treat the deformity. The models' behavior was governed solely by patient bodyweight, soft tissue constraints, muscle loading, and joint contact without the assumption of idealized joints. The current work expanded those models to determine if an alternate procedure would be more effective for the individual. All procedures incorporated first a tendon transfer and then included one hindfoot procedure, the Medializing Calcaneal Osteotomy (MCO), and one of three lateral column procedures: Evans osteotomy, Calcaneocuboid Distraction Arthrodesis (CCDA), Z osteotomy, and the combination procedures MCOEvans osteotomy, MCOCCDA, and MCOZ osteotomy. The combination MCOEvans and MCOZ procedures were shown to provide the greatest amount of correction for both forefoot abduction and hindfoot valgus. However, these two procedures significantly increased joint contact force, specifically at the calcaneocuboid joint, and ground reaction force along the lateral column. With exception to the lateral bands of the plantar fascia and middle spring ligament, the strain present in the plantar fascia, spring, and deltoid ligaments decreased after all procedures. The use of patient specific computational models provided the ability to investigate effects of alternate surgical corrections on restoring biomechanical function in these flatfoot patients. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1523-1531, 2017.

Background: This study evaluated the effects of locking vs nonlocking configuration on the biomechanical performance of a calcaneal reconstruction plate in an osteoporotic cadaveric model. Materials and Methods: A Saunders II B type calcaneal fracture was created in ten matched pair of cadaveric calcanei. Each pair was fixed with the Ascension calcaneal reconstruction plate using either locking or nonlocking screws in the same hole pattern. Specimens were axially loaded for 1000 cycles through the talus followed by load to failure. Statistical comparisons were made between the locking and nonlocking constructs on the displacements during cyclic loading as well as construct stiffness and load achieved at selected fragment displacements. Results: No significant difference was detected between the locking and nonlocking constructs in displacement during cyclic loading ( p >0.2) for the numbers available. Similarly no significant difference was found in stiffness of the constructs between the groups: 445.7 ± 148.8 (N/mm ± SD) for the locking plate and 395.2 ± 127.7 for the nonlocking plate ( p >0.14). The load achieved at 2 mm displacement of the posterior fragment for the two groups were not different: locking plate at 744.6 ± 237.2 N and nonlocking plate at 739.3± 269.7 N ( p >0.99). Conclusion: This study did not reveal a mechanical advantage to locking technology for calcaneal fractures with the selected plate and fracture model. Clinical Relevance: While locking plate technology has shown mechanical advantages for fracture management in other osteoporotic models, in our fracture model and plating construct, this was not found. It is still unclear which fixation technique is most beneficial in these calcaneal fractures.

Talonavicular fusion is performed for a variety of indications. This study examined the effects of fixation techniques on plantar pressures, construct stiffness, and strength.Eight matched pairs of cadaveric lower extremities were axially loaded intact and after talonavicular fixation with a 3.5 reconstruction plate, reconstruction plate plus cancellous screw (plate/screw), or three screws (screws). Recorded plantar pressures were divided into three forefoot, two midfoot, and two hindfoot regions. Cantilevered bending of excised constructs provided stiffness data for plantar and lateral directions, and failure characteristics in plantar bending.Relative to the intact state, all fixations decreased peak pressure in the medial forefoot, while generally increasing it in the lateral forefoot and midfoot. Average pressure shifted laterally for all fixation methods in the forefoot, generally in the hindfoot and the lateral midfoot. Generally, contact areas decreased in the medial forefoot, midfoot, and hindfoot while increasing laterally in the midfoot and hindfoot. The only difference among fixation methods was a decreased medial midfoot contact area for screws. No differences were found between screws and plate/screw in bending stiffness or failure (p0.5 and p0.2 respectively). Plantar and lateral bending stiffness for the plate/screw method averaged approximately 363 N/mm while stiffness of the screw only construct averaged approximately 380 N/mm. The load to failure averaged 946 N for the plate/screw construct and 1099 N for the screw construct.This study showed lateralization of plantar pressures following talonavicular fixation. Minimal differences were found between plate/screw and screws. Fixation across the joint may be key to achieving stability sufficient to resist shear and rotational stresses.Plate/screw or screws would likely be similarly effective in fusing the talonavicular joint. However, the fusion induced lateralization of plantar pressures may unintentionally result in adjacent joint arthritis and foot pain.

Posterior tibial tendon insufficiency, or adult acquired flatfoot deformity, involves collapse of the longitudinal arch of the foot with ensuing changes in the bony architecture of the foot as well. While it is generally accepted that a medializing calcaneal osteotomy (MCO) is a very useful treatment for restoring the fallen arch, questions regarding the effects of this procedure upon plantar foot pressures and Achilles tendon length changes need to be answered. This study focuses on changes in plantar foot pressures and Achilles tendon length as the result of performing a MCO. Fourteen fresh-frozen cadaver legs were used to test the effects of MCO on Achilles tendon length changes 2 cm proximal to the Achilles tendon insertion on the calcaneus. Differential variable reluctance transducers were anchored in ventromedial, dorsomedial, dorsolateral, and ventrolateral positions of the Achilles tendon at the aforementioned level. The effects of the MCO on plantar foot pressures were assessed simultaneously using the Tekscan HR Mat. Axial loading (100 lbs) of each specimen was performed in neutral and dorsiflexion (15°). Data were gathered for Achilles tendon length changes and plantar foot pressures for three trials in both the neutral and dorsiflexed positions. A medializing calcaneal osteotomy (1 cm medial translation) was then performed and testing was repeated in the fashion outlined heretofore. Analysis of the data revealed that there was no significant increase in Achilles tendon length as a result of the MCO. The data also showed that average pressure over the first and second metatarsal regions of the forefoot decreased significantly after MCO. At the same time there was a significant increase in average pressure over the medial and lateral aspect of the heel. These findings suggest that the Achilles tendon aids in inversion of the forefoot without undergoing a significant increase in length change of Achilles tendon fibers in any of the regions tested.

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.

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.

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° compared with 3.2°) and of the first metatarsal plantarflexion (2.3° compared with 3.2° 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.

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° manually (± 2.75°) and 7.7° mechanically (± 2.95°)] 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.

Adult acquired flatfoot deformity is a degenerative disease causing medial arch dysfunction. Surgical correction has typically involved tendon reconstruction with calcaneal osteotomy; however, the postoperative changes have not been fully characterized. The present study assessed the success of surgical correction of Stage IIb adult acquired flatfoot deformity through changes in plantar pressures and patient-generated outcome scores. With Institutional Review Board approval, 6 participants were evaluated before and after surgery using pedobarography, the Foot and Ankle Outcome Score, and the Medical Outcomes Study 36-item short-form questionnaire. The plantar pressures were recorded using a TekScan HRMat during walking and in a 1- and 2-foot stance. The resulting contour maps were segmented into 9 regions, with the peak pressure, normalized force, and arch index calculated. Surgical effects were analyzed using paired t tests. Postoperatively, the Foot and Ankle Outcome Score and Medical Outcomes Study 36-item short-form questionnaire scores increased significantly from 180 � 78 to 360 � 136 (p < .03) and 47 � 18 to 71 � 19 (p ¼ .06), respectively. During the 2-foot stance, the normalized force had increased significantly in the lateral midfoot (p < .03), although no significant differences were found in peak pressures. No significant differences were observed in the 1-foot stance. During walking, the normalized force increased significantly in the lateral midand forefoot (p < .05). The peak pressure increased significantly in the lateral forefoot (p < .01). The arch index values demonstrated no significant changes. The increased questionnaire scores indicated that surgical correction improved the self-perceived health of the participants. Lateral shifts in the peak pressure and normalized force suggest that forefoot and midfoot loading is altered postoperatively, consistent with the goal of offloading the dysfunctional arch. Thus, the present study has demonstrated that surgical treatment of adult acquired flatfoot deformity can be accurately assessed using patient-reported outcome measures and plantar pressures.

Adult Acquired Flatfoot Deformity (AAFD) is a degenerative disease characterized by chronic changes in the joint alignment of the bones of the foot leading to significant pain and dysfunction. The hallmark of this disease is the functional loss in posterior tibialis tendon (PTT) strength though mechanical degradation of passive support structures of the foot have also been implicated, namely the spring ligament, talocalcaneal interosseous ligaments, fibers of the anterior deltoid, and the long and short plantar ligaments. [1] Clinically, AAFD patients present with midfoot collapse, forefoot abduction, and valgus tilting of the hindfoot and the magnitudes of these deformities are most often graded using plane radiographs in the mediolateral (ML), oblique anteroposterior (AP) and posteroanterior (PA) views. [1–3] The objective of this study was to develop a population of patient-matched rigid-body kinematic models using a standardized methodology that can be used to predict pathologic foot function with agreement between patient and model assessed through clinically relevant radiographic joint angles.Copyright © 2013 by ASME

The ankle joint, comprised of the distal ends of the tibia and fibula as well as talus, is key in permitting movement of the foot and restricting excessive motion during weight-bearing activities. Medial ankle injury occurs as a result of pronation-abduction or pronation-external rotation loading scenarios in which avulsion of the medial malleolus or rupture of the deltoid ligament can result if the force is sufficient [1]. If left untreated, the joint may experience more severe conditions like osteoarthritis [2]. To avoid such consequences, medial ankle injuries — specifically bony injuries — are treated with open reduction and internal fixation via the use of plates, screws, wires, or some combination thereof [1, 3–4]. In this investigation, the mechanical performance of two such devices was compared by creating a 3-dimensional model of an earlier cadaveric study [5], validating the model against the cadaveric data via finite element analysis (FEA), and comparing regions of high stress to regions of experimental failure.Copyright © 2013 by ASME

Adult acquired flatfoot deformity (AAFD) is a degenerative disease resulting in malalignment of the mid- and hindfoot secondary to posterior tibial tendon dysfunction and increasing implication of ligament pathologies. Despite the complex 3D nature of AAFD, 2D radiographs are still employed to diagnose and stage the disease. Computer modeling techniques allow for accurate 3D recreations of musculoskeletal systems for the investigation of biomechanical factors contributing to disease. Following Institutional Review Board approval, the lower limbs of six diagnosed AAFD sufferers were imaged with MRI, photographs, and X-ray. Next, a radiologist graded the MRI attenuation of eight soft-tissues implicated in AAFD. Six patient-specific rigid-body models were then created and loaded according to patient weight, graded soft-tissues, and extrinsic muscles. Model function was validated using clinically relevant kinematic measures in three planes. Agreement varied depending on the measure, with average absolute deviations of7° for angles and4 mm for distances. Additionally, the clinically favored AP talonavicular coverage angle, ML talo-1st metatarsal angle, and ML 1st cuneiform height showed strong correlations of R(2) = 0.63, 0.75, and 0.85, respectively. Thus, computer modeling offers a promising methodology for the non-invasive investigation of in vivo kinematic behavior in pathologic feet and, once validated, may further be used to investigate biomechanical parameters that are difficult to measure clinically.

Adult Acquired Flatfoot Deformity (AAFD) is a degenerative disease characterized by chronic changes in the joint alignment of the bones of the foot leading to significant pain and dysfunction. The early stages of the disease are thought to involve primarily the mechanical degradation of the soft-tissue support structures of the foot, namely the spring ligament, talocalcaneal interosseous ligaments, fibers of the anterior deltoid, and the long and short plantar ligaments, as well as a functional loss in posterior tibialis tendon (PTT) strength. [1] These changes manifest clinically as midfoot collapse, forefoot abduction, and valgus tilting hindfoot. [1–3] Various surgical corrections exist for Stage II AAFD to restore more normal biomechanical function to the foot. Treatment selection is most often based on clinical outcomes and surgeon preference. However, the optimal procedure(s) for an individual patient is unknown. Computer Aided Design (CAD) approaches offer advantages for evaluating foot function as well as the ability to predict pre-operatively the outcome of corrective procedures. This study developed a 3D patient specific computer model of the lower leg from a diagnosed Stage II flatfoot patient and evaluated its ability to predict foot function pre- and post-operatively through agreement with clinically relevant radiographic joint angles.Copyright © 2012 by ASME

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.

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.

Background: Research into gait characteristics has led to the creation of experimental gait simulators. The aim of this work was the development of a Contact Gait Simulation System (CGSS) to generate realistic plantar pressures for the contact phase of gait. The simulator seeks to create muscle loads which guide the foot through the entire loaded contact phase. Methods: Two simulations, mid stance only ( n = 8) and full contact gait ( n = 7) were applied to cadaveric lower extremities disarticulated at the knee. The Achilles, extensor digitorum, and extensor hallucis longus tendons were clamped for the application of muscular loads while axial loads were applied to the proximal tibia and plantar pressures were measured. Live subjects ( n = 7) were recorded traversing the plantar pressure sensor, for regional (fore, mid, and hind foot) pressure comparisons. Results: By loading muscle tendons in proportion to live gait, the generated patterns of loading across the fore, mid and hind foot were representative of that found in live subjects. Hindfoot pressures dominated during the initial loading response, while forefoot pressures dominated during the terminal stance phase of gait. Regional trends showed strong similarity in timing and proportion to live gait. Conclusions: The CGSS developed is capable of simulating live plantar pressures in the cadaveric model. Further manipulation of simulator control signals may improve accuracy, but as gait characteristically exhibits broad trends, exact agreement is not necessary. Clinical Relevance: We believe this System can be used to efficiently investigate the alterations to foot/ankle function resulting from injuries and surgical corrective procedures.

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.

BackgroundAnkle 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.MethodsThe 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.ResultsResults 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 XCaliber's 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.ConclusionsThe present study demonstrates that the XCaliber has mechanical advantages over the Hoffmann®II in terms of torsional rigidity for a tibial pilon fracture.Clinical RelevanceIncreased 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.

The medial calcaneal osteotomy (MCO) is a frequently used corrective procedure for posterior tibial tendon (PTT) insufficiency; however, patients often complain of lateral foot pain postoperatively. Published findings have documented the usefulness of MCO in off-loading the plantar surface of the first and second metatarsal heads but with a concomitant increase in peak pressure over the lateral forefoot and heel. Achilles tendon elongation revealed a trend toward shortening of the ventromedial aspect of the tendon. It was then hypothesized that translating the osteotomized posterior aspect of the calcaneus medially and superiorly would reduce lateral forefoot pressure and decrease the amount of lengthening of the Achilles tendon while continuing to relieve medial forefoot pressure.Twenty-eight fresh-frozen cadaver legs were axially loaded on a load-frame device to 100 lbs to assess the effects of a 1-cm MCO in conjunction with either 0.5-cm or 1-cm superior translation on plantar foot pressures and Achilles tendon elongation.The 0.5-cm superior translation resulted in a greater off-loading of the first and second metatarsals than the MCO alone with a trend toward decreased pressures in the lateral forefoot. The 1-cm superior translation continued to unload the first and second metatarsals; however, lateral forefoot and midfoot pressures were increased. Achilles tendon lengthening remained unchanged in the cadaver foot model.Our findings suggest that the addition of a 0.5-cm superior translation to the traditional 1-cm MCO should allow some degree of off-loading of the medial forefoot without increasing lateral forefoot or heel pressures.

Background: Since metatarsal osteotomy was first used to treat metatarsalgia in the early twentieth century, many techniques have been described to accomplish the basic aim of reduction of load transmission through the operated metatarsal and reduction of localized high pressure on the plantar surface of the metatarsal. Our study examined two popular distal metatarsal neck osteotomies used for the relief of central metatarsalgia and the biomechanical changes that result from their use in a cadaver forefoot model. Methods: After applying 445N (100 lbs) of axially directed force, we measured plantar pressure using the TekScan HR Mat™ (TekScan, Inc., South Boston, MA) in twelve paired, thawed, fresh-frozen intact cadaver legs, then after either a Weil or chevron osteotomy of the second metatarsal and finally after the addition of the same osteotomy of the third metatarsal. Results: Load in the forefoot was not significantly affected by the Weil osteotomy. A significant increase in load was produced in the first metatarsal region, and significant decreases in load were produced beneath the operated metatarsal heads after the chevron osteotomy. Average pressure in the contact area of the forefoot showed similar trends; however, load and pressure changes occurred independently, owing to the changes in contact area produced by the osteotomies. No significant changes were observed in the nonoperated metatarsal regions. Conclusions: In this model, the chevron osteotomy more effectively reduced load and plantar pressure in the operated metatarsal regions; however, increases in load and pressure were observed in the first metatarsal region. The increase in pressure without a change in load in region 3 (third metatarsal) after a Weil osteotomy of the third metatarsal was attributed to the creation of a plantar prominence. This study did not show a reduction in load transmission as a result of the Weil osteotomy, which contradicts the proposed mechanism of clinical benefit. An intact first ray likely prevents transfer of load or pressure to adjacent lesser metatarsals with chevron osteotomy.

Avascular necrosis (AVN) of the talus has always been a surgical challenge because the talus is hidden by its anatomic location and has a precarious blood supply. Most cases (75%) of talar AVN are traumatically induced in association with talar body and talar neck fractures.AVN of the talus can be a significant problem because collapse of the talar dome leads to degenerative changes and pain and disability of the ankle and subtalar joints. Although there are many published treatments for posttraumatic AVN of the talus, critical outcome studies are still lacking.

✓ 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.

Numerous reconstructive procedures are performed to correct both ankle and subtalar instability after trauma although the precise pathology which results in this chronic instability and pain is not yet known. This study examined the role of the calcaneofibular (CLFL) and cervical ligaments (CRVL) during physiologic loading and demonstrated the effect of CLFL deficiency on the CRVL. Talar and subtalar tilt as well as inversion range of motion before and after CLFL sectioning were studied. Eleven osteoligamentous fresh frozen cadaver legs were used in which each foot was taken through six positions: neutral, 35 degrees plantarflexion, dorsiflexion, inversion, plantarflexion-inversion, and dorsiflexion-inversion. The CLFL and CRVL stretched the greatest in dorsiflexion-inversion. The most interesting finding was that the CRVL was elongated relative to neutral in all other test positions of the foot. However, the CLFL was shortened relative to neutral in plantarflexion and plantarflexion-inversion. In the CLFL deficient state, CRVL ratios demonstrated significant increases in length of the CRVL. Talar tilt increased on average more than 9 degrees with CLFL deficiency (p < 0.008) while subtalar tilt did not change significantly. The maximum tibiocalcaneal angle, recorded for dorsiflexion-inversion, increased more than 5 degrees after sectioning the CLFL (p < 0.05).

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° dorsiflexion, and 10° 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.

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 axi-ally 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 medial 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.

Sarcoidosis of the skeletal system is not rare but problems related to it are unusual. Two cases of sarcoidosis, with involvement of the upper extremity, are presented to point out problems that may occur in its treatment. Osteolytic sarcoid involvement of the phalanges leads to resorption and collapse, with a poor response to bone grafting or splinting. The phalangeal collapse could be treated with intramedullary cement or Kirschner wire fixation. Sarcoid involvement of fractures can lead to a nonunion and they should be treated with excision when appropriate, rather than attempting osteosynthesis. Arteriograms of sarcoid lesions show them to have a very poor blood supply. A bone scan can be used to demonstrate areas of sarcoid involvement before the characteristic lesion becomes evident on a radiography.

The foot and ankle is a complex structure made of many small bones with capsular and ligamentous con straints. The physiology, kinematics, and muscle inter action of the walking, jogging, and running cycles will be discussed and the current biomechanical literature reviewed. To analyze the pathologic state, one must be aware of the normal stresses and functions of the running cycle. This knowledge establishes a rational basis for the interpretation of problems in providing medical and orthotic treatment.

A number of factors that influence the success of microvascular anastomosis have been studied, including adventitial stripping, choice of suture material and needles, suturing technique, and perfusion of the distal lumen. It is apparent that only minimal stripping of the adventitia is indicated in order to prevent increased necrosis of the vessel ends at the anastomosis site. The use of 10-0 monofilament nylon suture material with needles 75 microns or less in diameter achieves the best results in small vessel anastomoses. Optimal anastomosis of 1 mm. vessels requires interrupted full thickness sutures with minimal adventitial stripping and the use of the smallest number of sutures possible. We do not advocate routine perfusion of small arteries unless there are specific indications. An experienced team of microsurgeons utilizing these principles along with proper patient selection and a sound postoperative regimen should be able to achieve more than a 70 per cent success rate in replantation of completely amputated digits and hands.

Treatment by in situ release, submuscular transposition, and anterior subcutaneous transposition have all been reported to produce satisfactory results for ulnar neuropathy secondary to the cubital tunnel syndrome. A prospective study was done to determine which preoperative clinical and electrical factors and surgical approaches in patients with ulnar nerve palsy at the elbow had the best results. The 32 patients had an average age of 50 years, had symptoms for an average of 15 months before surgery, and underwent postoperative follow-up for an average of 13 months. All patients with good results had no atrophy or preoperative fibrillations in the intrinsic muscles and had an obtainable evoked sensory potential. The change in motor conduction velocity did not correlate with good results. There was no significant difference in the results of the three surgical procedures. Eight of the 37 operations yielded good results, 19 patients showed an improvement, but 10 of the operations yielded poor results. Our results also indicated that surgical results could be predicted by proper patient selection through the assessment of the preoperative physical examination and electromyogram.

The preliminary results of a comprehensive talipes equinovarus release on 16 patients with 20 idiopathic clubfoot deformities were analyzed with an 18-month follow-up. Our conclusions were that each component of the clubfoot can be managed in a single stage operative procedure without any significant risk to the patient; bilateral surgery could be done at the same sitting; and dorsiflexion was difficult to achieve because of the anatomical deformity of the talus and resistant anterior capsule. Fixation after comprehensive release with Kirschner wires is important in maintaining the reduction, and no patient had a return of the deformity after satisfactory correction at the time of surgery. The complications were excessive hindfoot valgus, loss of the longitudinal arch by excessive midfoot release and casts, and forefoot valgus from complete transfer of the anterior tibial.

Isolated fracture of the greater multangular (trapezium) is rare. Due to its anatomical position and overlying carpal bones, this fracture becomes a difficult diagnostic problem. Vertical fractures of the greater multangular along the coronal axis are usually missed on routine AP, lateral, and oblique views of the wrist. Persistent disabling symptoms, abnormal physical examination with a negative standard radiographic study of the wrist should cause suspicion. Occasional attention has been drawn in the orthopaedic literature to the value of the carpal tunnel view in the detection of these fractures (Cordrey & Ferrer-Torells, 1960; McClain & Boyes, 1966; Rockwood & Green, 1975). The radiological literature does not stress this important practical application of the carpal tunnel view. We wish to present a case in which this was the only projection demonstrating this fracture.