In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ...ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue's elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system.
RSNA, 2017.
Background
In 2012, the American Orthopaedic Foot & Ankle Society
®
established a national network for collecting and sharing data on treatment outcomes and improving patient care. One of the ...network’s initiatives is to explore the use of computerized adaptive tests (CATs) for patient-level outcome reporting.
Questions/purposes
We determined whether the CAT from the NIH Patient Reported Outcome Measurement Information System
®
(PROMIS
®
) Physical Function (PF) item bank provides efficient, reliable, valid, precise, and adequately covered point estimates of patients’ physical function.
Methods
After informed consent, 288 patients with a mean age of 51 years (range, 18–81 years) undergoing surgery for common foot and ankle problems completed a web-based questionnaire. Efficiency was determined by time for test administration. Reliability was assessed with person and item reliability estimates. Validity evaluation included content validity from expert review and construct validity measured against the PROMIS
®
Pain CAT and patient responses based on tradeoff perceptions. Precision was assessed by standard error of measurement (SEM) across patients’ physical function levels. Instrument coverage was based on a person-item map.
Results
Average time of test administration was 47 seconds. Reliability was 0.96 for person and 0.99 for item. Construct validity against the Pain CAT had an r value of −0.657 (p < 0.001). Precision had an SEM of less than 3.3 (equivalent to a Cronbach’s alpha of ≥ 0.90) across a broad range of function. Concerning coverage, the ceiling effect was 0.32% and there was no floor effect.
Conclusions
The PROMIS
®
PF CAT appears to be an excellent method for measuring outcomes for patients with foot and ankle surgery. Further validation of the PROMIS
®
item banks may ultimately provide a valid and reliable tool for measuring patient-reported outcomes after injuries and treatment.
Level of Evidence
Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.
Abstract Objective To examine the effect of a 12-week Tai Chi (TC) intervention on physical function and quality of life. Design Single-blind, randomized controlled trial. Setting General community. ...Participants Community-dwelling survivors of stroke (N=145; 47% women; mean age, 70y; time poststroke: 3y; ischemic stroke: 66%; hemiparesis: 73%) who were aged ≥50 years and were ≥3 months poststroke. Interventions Yang style 24-posture short-form TC (n=53), strength and range of movement exercises (SS) (n=44), or usual care (UC) (n=48) for 12 weeks. The TC and SS groups attended a 1-hour class 3 times per week, whereas the UC group had weekly phone calls. Main Outcome Measures Physical function: Short Physical Performance Battery, fall rates, and 2-minute step test; quality of life: Medical Outcomes Study 36-Item Short-Form Health Survey, Center for Epidemiologic Studies Depression Scale, and Pittsburgh Sleep Quality Index. Results During the intervention, TC participants had two thirds fewer falls (5 falls) than the SS (14 falls) and UC (15 falls) groups (χ2 =5.6, P =.06). There was a significant group by time interaction for the 2-minute step test (F2,142 =4.69, P <.01). Post hoc tests indicated that the TC ( t53 =2.45, P =.02) and SS ( t44 =4.63, P <.01) groups had significantly better aerobic endurance over time, though not in the UC group ( t48 =1.58, P =.12). Intervention adherence rates were 85%. Conclusions TC and SS led to improved aerobic endurance, and both are suitable community-based programs that may aid in stroke recovery and community reintegration. Our data suggest that a 12-week TC intervention was more effective in reducing fall rates than SS or UC interventions. Future studies examining the effectiveness of TC as a fall prevention strategy for community-dwelling survivors of stroke are recommended.
Ankle sprains are common injuries involving the lateral ankle ligaments and affect athletes of all levels. Most patients heal uneventfully, but those with symptoms persisting past 3 months should be ...evaluated for chronic ankle instability and its associated conditions as well as for the presence of varus malalignment. Chronic ankle instability is initially treated nonoperatively, with surgical management reserved for those who have failed to improve after 3 to 6 months of bracing and functional rehabilitation. Anatomic repair using a modification of the Broström procedure is the preferred technique for initial surgery. Anatomic reconstruction with tendon graft should be considered when repair is not possible, as it maintains physiological joint kinematics. Nonanatomic reconstructions are seldom indicated. Arthroscopic repair or reconstruction of the lateral ankle ligaments is a promising new technique with results similar to those of open surgery.
Patients with posterior tibial tendon dysfunction (PTTD) may exhibit postural instability during walking likely due to a loss of medial longitudinal arch, abnormal foot alignment, and pain. While ...many studies have investigated gait alterations in PTTD, there is no understanding of dynamic postural control mechanisms in this population during gait, which will help guide rehabilitation and gait training programs for patients with PTTD. The purpose of the study was to assess dynamic postural control mechanisms in patients with stage II PTTD as compared to age and gender matched healthy controls.
Eleven patients with stage II PTTD (4 males and 7 females; age 59 ± 1 years; height 1.66 ± 0.12 m; mass 84.2 ± 16.0 kg) and ten gender and age matched controls were recruited in this study. Participants were asked to walk along a 10 m walkway. Ten Vicon cameras and four AMTI force platforms were used to collect kinematic and center of pressure (COP) data while participants performed gait. To test differences between PTTD vs. control groups, independent
-tests (set at α < 0.05) were performed.
Patients with PTTD had significantly higher double stance ratio (+23%) and anterior-posterior (AP) time to contact (TTC) percentage (+16%) as compared to healthy control. However, PTTD had lower AP COP excursion (-19%), AP COP velocity (-30%), and medial-lateral (ML) COP velocity (-40%) as compared to healthy controls. Mean ML COP trace values for PTTD were significantly decreased (-23%) as compared to controls, indicating COP trace for PTTD tends to be closer to the medial boundary than controls during single-support phase of walking.
PTTD patients showed more conservative and cautious postural strategies which may help maintain balance and reduce the need for postural adjustment during PTTD gait. They also showed more medially shifted COP patterns than healthy controls during single-support phase of walking. Dynamic postural control outcomes could be used to develop effective gait training programs aimed at alleviating a medial shift of COP (everted foot) for individuals with PTTD in order to improve their functionality and gait efficiency.
Background
Symptomatic progressive collapsing foot deformity (PCFD) is frequently treated with reconstructive surgery. Multiple studies have documented successful treatment based on improvements in ...symptoms and physical examination findings. However, it is not well-established whether there are corresponding improvements in gait function following surgical treatment for PCFD.
Methods
A systematic review of biomechanical outcomes of treatments for flexible PCFD was conducted on PubMed. The 4 articles chosen involved patients with symptomatic flexible PCFD who underwent a reconstructive surgery. Surgical interventions included osteotomy, tendon transfer, and/or ligament repair or reconstruction. Primary outcomes involved objective quantifiable measurements of kinematic, kinetic, or temporospatial parameters.
Results
The initial search yielded 605 articles, from which 26 were retained after screening the title and abstract. Twenty-two were eliminated yielding 4 articles. Temporospatial, kinematic, and kinetic parameters were all altered after the patients underwent surgical intervention. Specifically, stride length, cadence, and walking speed all improved postoperatively. Walking kinetics also improved with restoration of normal motion in the frontal and sagittal planes and improvements in the dorsiflexion angle. There were also improvements in sagittal power.
Discussion
Surgical intervention to treat flexible PCFD improves objective biomechanical outcomes; however, more follow-up studies are needed to establish the reliability and durability of these improvements.
Level of Evidence:
Level III: Systematic review
Category:
Midfoot/Forefoot; Hindfoot
Introduction/Purpose:
Triceps surae muscle force is transferred through the Achilles tendon to the calcaneus and from the calcaneus to the plantar fascia and then ...to the metatarsal heads and the toes which exert force on the ground. Achilles tendon ruptures occur in tendons that have reached a critical point of intrasubstance degeneration. The Achilles tendon almost always heals but frequently lengthens during the healing process, leading to an alteration in the triceps surae force production profile. We hypothesized that Achilles tendon overlengthening has implications not only for force generation but likely has many other impacts throughout the foot. The goal of this work was to evaluate the effect of a lengthened Achilles tendon following tendon repair on the kinetics of the foot.
Methods:
A validated finite element model of the foot was used to compare foot biomechanics between the foot with a functional and non-functional Achilles tendon. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The tendon forces were applied using force vectors in the direction of their lines of action. The foot with a non-functional Achilles tendon was created by unloading the Achilles tendon since triceps surae muscle shortening due to tendon lengthening significantly decreases force production. The force transmitted through the joints, force in the ligaments, and plantar pressure were determined for both the foot with a functional and non-functional Achilles tendon.
Results:
We found that the force transmitted through all the joints decreased when the Achilles tendon force was removed (Figure 1a). In addition, removing the Achilles tendon decreased the force within the plantar fascia, long and short plantar ligaments, and deep deltoid ligament, while it increased the force within the spring and superficial deltoid ligaments (Figure 1b). The plantar fascia experienced the greatest reduction in ligament force after unloading of the Achilles tendon (from 93 N to 26 N). Moreover, the maximum plantar pressure in the heel fat pad increased from 164 kPa to 231 kPa when the Achilles tendon was removed.
Conclusion:
The varying changes in the force in the ligaments and joints due to Achilles lengthening suggest that Achilles tendon rupture with sequent healing with overlengthening can alter the force distribution throughout the entire foot. A major implication of this work is that in treating Achilles ruptures, an extended period of protection with heel wedges beyond the customary six weeks may be needed to prevent over lengthening of the Achilles. Moreover, this study supports the efficiency of surgical lengthening of the Achilles in the treatment of diabetic forefoot foot ulcers by shifting the plantar pressure towards the calcaneus.
Category:
Hindfoot; Midfoot/Forefoot
Introduction/Purpose:
The osseous structure of the foot has been described as an arch-like triangular structure or truss where the plantar fascia (PF) functions ...as the tensile element, maintaining the overall length of the arch. The importance of the PF in maintaining the arch has likely been underestimated because only minor abnormalities in its structure are seen on MRI studies in patients with flatfoot deformity. However, the importance of a ligament in preventing deformity may not be correlated with its attenuation seen on MRI. We hypothesized that the degenerative elongation of the plantar fascia would be a necessary precursor of arch collapse. The goal of this study was to evaluate the role of the plantar fascia in arch stability in flatfoot deformity.
Methods:
We used a validated finite element model of the foot reconstructed from CT scan of a female cadaveric foot weighing 60 kg. The model included 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The flatfoot model was created by simulated transection of the ligaments and unloading of the posterior tibial tendon. The model was used to assess the impact of isolated PF failure on the development of flatfoot deformity, evaluate the capability of the PF when reconstructed to restore foot alignment, and determine the amount of progressive strain that constitutes failure for each ligament. Foot alignment angles were used to evaluate the foot alignment. For comparison, the angles were also evaluated for other ligament tears. The impact of PF failure on force changes in the remaining ligaments was also investigated by quantifying ligament force changes during simulated PF cutting in the foot model.
Results:
When compared to the intact and flatfoot models, we found that the individual release of the PF cannot cause deformity (Figure 1). However, it significantly increased the force in the long (142%) and short plantar (156%), deltoid (45%), and spring ligaments (60%), potentially putting the foot at risk of arch instability over time. Moreover, we found that the PF was the structure most able to restore the arch (Figure 1a). The PF was also found to play a secondary role in reducing hindfoot valgus and forefoot abduction deformities (Figures 1b,1c). Moreover, to produce deformity, a considerable amount of attenuation in the spring (strain= 41%) and interosseous talocalcaneal ligament (strain= 27%), but only a small amount in the plantar fascia (strain= 10%) was needed.
Conclusion:
In comparing normal to flatfoot models of the foot, we found that isolated PF release did not cause arch collapse, but that arch collapse could not occur without elongation of the PF. While the progressive strain in the PF needed to enable arch collapse was small, the PF is a very long ligament, thus even small strain within the PF corresponds to substantial change in overall length of the arch. Chronic degeneration of the PF leading to plantar fasciitis may be an early sign of impending flatfoot deformity.
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