L. Daniel Latt

Effect of Tai Chi on Physical Function, Fall Rates and Quality of Life Among Older Stroke Survivors

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 (χ(2)=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.

Psychometric Comparison of the PROMIS Physical Function CAT With the FAAM and FFI for Measuring Patient-Reported Outcomes

Background: Selecting optimal patient-reported outcome (PRO) instruments is critical to improving the quality of health care. The purpose of this study was to compare the reliability, responsiveness, and efficiency of three PRO measures: the Foot and Ankle Ability Measure–Activity of Daily Living subscale (FAAM_ADL), the Foot Function Index 5-point verbal rating scale (FFI-5pt), and the PROMIS Physical Function computerized adaptive test (PF CAT). Methods: Data were aggregated from 10 clinical sites in the AOFAS’s National Orthopaedic Foot and Ankle Research (OFAR) Network from 311 patients who underwent elective surgery for a disorder of the foot or ankle. Patients were administered the FAAM_ADL, FFI-5pt, and PF CAT at their preoperative visit and at 6 months after surgery. Reliabilities were evaluated using a Rasch model. Responsiveness was calculated using paired samples t test and efficiency was recorded as number of seconds to complete the instrument. Results: Similar reliabilities were found for the three instruments. Item reliabilities for FAAM_ADL, FFI-5pt, and PF CAT were all .99. Pearson reliabilities for FAAM_ADL, FFI-5pt, and PF CAT were .95, .93, and .96, respectively. On average, patients completed the FAAM_ADL in 179 seconds, the FFI-5pt in 194 seconds, and the PF CAT in 44 seconds, (P < .001). The PF CAT and FAAM_ADL showed significant improvement (P = .01 and P = .001, respectively) in patients’ physical function after treatment; the FFI-5pt did not show improvement. Conclusions: Overall, the PF CAT performed best in terms of reliability, responsiveness, and efficiency in this broad sample of foot and ankle patients. It can be a potential replacement for the conventional PRO measures, but further validation is needed in conjunction with the PROMIS Pain instruments. Level of Evidence: Level I, prospective comparative outcome study.

Effect of Graft Height Mismatch on Contact Pressures With Osteochondral Grafting of the Talus

Background: Osteochondral allograft transplantation is technically demanding. It is not always possible to place the surface of the graft perfectly flush with the surrounding cartilage. One must often choose between placing at least some portion of the surface of the graft slightly elevated or recessed. The effect of this choice on joint contact pressure is unknown. Purpose: This study was undertaken to determine the effect of graft height mismatch on joint contact pressure in the ankle. Study Design: Controlled laboratory study. Methods: Ten human cadaveric ankles underwent osteochondral grafting by removal then replacement of an osteochondral plug. Six conditions were tested: intact, graft flush, graft elevated 1.0 mm, graft elevated 0.5 mm, graft recessed 0.5 mm, and graft recessed 1.0 mm. Joint contact pressures were measured with a Tekscan sensor while loads of 200 N, 400 N, 600 N, and 800 N were sequentially applied. Results: The peak contact pressure at the graft site for the flush condition was not significantly different from the intact condition for either medial or lateral lesions. In contrast, peak pressure on the opposite facet of the talar dome was significantly increased during the flush condition for the medial but not the lateral grafts. Elevated grafts experienced significantly increased contact pressures, whereas recessed grafts experienced significantly decreased pressures. These changes were greater for lateral than for medial lesions. Reciprocal changes in joint contact pressures were found on the opposite facet of the talus with elevated grafts on the lateral side and recessed grafts on the medial side. Conclusion: Flush graft placement can restore near-normal joint contact pressure. Elevated graft placement leads to significant increases in joint contact pressure at the graft site. Recessed graft placement leads to a transfer of pressure from the graft site to the opposite facet of the talus. Clinical Relevance: Osteochondral grafts in the talus should be placed flush if possible or else slightly recessed.

The Orthopaedic Foot and Ankle Outcomes Research (OFAR) network: feasibility of a multicenter network for patient outcomes assessment in foot and ankle.

Introduction: There is an increasing need for orthopaedic practitioners to measure and collect patient-reported outcomes data. In an effort to better understand outcomes from operative treatment, the American Orthopaedic Foot & Ankle Society (AOFAS) established the Orthopaedic Foot and Ankle Outcomes Research (OFAR) Network, a national consortium of foot and ankle orthopaedic surgeons. We hypothesized that the OFAR Network could successfully collect, aggregate, and report patient-reported outcome (PRO) data using the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS). Methods: Ten sites enrolled consecutive patients undergoing elective surgery for 1 of 6 foot/ankle disorders. Outcome instruments were collected preoperatively and at 6 months postoperatively using the PROMIS online system: Foot and Ankle Ability Measure (FAAM), Foot Function Index (FFI), and PROMIS physical function (PF) and pain computerized adaptive tests (CAT). During the 3-month period, 328 patients were enrolled; 249 (76%) had completed preoperative patient-reported outcomes data and procedure-specific data. Of these, 140 (56%) also completed 6-month postoperative patient- reported outcomes data. Results: Ankle arthritis and flatfoot demonstrated consistently worse preoperative scores. Five of 6 disorders showed significant improvement at 6 months on PF CAT and FAAM, 4 of 6 showed improvement on pain interference CAT, and no disorders showed improvement on FFI. Ankle arthritis and flatfoot demonstrated the greatest magnitude of change on most patient-reported outcomes scales. Conclusion: We were able to enroll large numbers of patients in a short enrollment period for this preliminary study. Data were easily aggregated and analyzed. Substantial loss of follow-up data indicates a critical area requiring further effort. The AOFAS OFAR Network is undergoing expansion with goals to ultimately facilitate large, prospective multicenter studies and optimize the quality and interpretation of available outcome instruments for the foot and ankle population. Level of Evidence: Level II, prospective comparative study.

Predictors of gait velocity among community-dwelling stroke survivors

INTRODUCTION Gait velocity is an objective, fundamental indicator of post-stroke walking ability. Most stroke survivors have diminished aerobic endurance or paretic leg strength affecting their walking ability. Other reported underlying factors affecting gait velocity include functional disability, balance, cognitive impairment, or the distance they are required to walk. OBJECTIVE To examine the relationship between gait velocity and measures of physical and cognitive functioning in chronic stroke. METHODS Cross-sectional design using baseline data from community-dwelling stroke survivors enrolled in an exercise intervention study. Functional disability (modified Rankin Scale), aerobic endurance (2-min step-test), leg strength (timed 5-chair stand test), balance (single-leg stance) and cognitive impairment (Mini-Mental Status Exam) were assessed. Gait velocity was assessed using a timed 4-m walk test. Multiple linear regression was used to explore potential independent predictors of gait velocity. RESULTS Subjects had an average gait velocity of 0.75±0.23m/s, categorized as limited community walkers. Approximately 37% of the variance in gait velocity, could be explained by the 5 independent variables, functional disability, aerobic endurance, leg strength, balance, and cognitive impairment (R(2)=0.37, F(5,74)=8.64, p<0.01). Aerobic endurance (t(1,74)=3.41, p<0.01) and leg strength (t(1,74)=-2.23, p=0.03) contributed significantly to gait velocity. CONCLUSION Diminished aerobic endurance and leg strength are major contributors to slow gait velocity in chronic stroke. Long term rehabilitation efforts are needed to improve gait velocity in chronic stroke, and may need to incorporate multifaceted strategies concurrently, focusing on aerobic endurance and leg strength, to maximize community ambulation and reintegration.

High-Resolution US and MR Imaging of Peroneal Tendon Injuries

Injuries of the peroneal tendon complex are common and should be considered in every patient who presents with chronic lateral ankle pain. These injuries occur as a result of trauma (including ankle sprains), in tendons with preexisting tendonopathy, and with repetitive microtrauma due to instability. The peroneus brevis and peroneus longus tendons are rarely torn simultaneously. Several anatomic variants, including a flat or convex fibular retromalleolar groove, hypertrophy of the peroneal tubercle at the lateral aspect of the calcaneus, an accessory peroneus quartus muscle, a low-lying peroneus brevis muscle belly, and an os peroneum, may predispose to peroneal tendon injuries. High-resolution 1.5-T and 3-T magnetic resonance (MR) imaging with use of dedicated extremity coils and high-resolution ultrasonography (US) with high-frequency linear transducers and dynamic imaging are proved to adequately depict the peroneal tendons for evaluation and can aid the orthopedic surgeon in injury management. An understanding of current treatment approaches for partial- and full-thickness peroneal tendon tears, subluxation and dislocation of these tendons with superior peroneal retinaculum (SPR) injuries, intrasheath subluxations, and peroneal tendonopathy and tenosynovitis can help physicians achieve a favorable outcome. Patients with low functional demands do well with conservative treatment, while those with high functional demands may benefit from surgery if nonsurgical treatment is unsuccessful. Radiologists should recognize the normal anatomy and specific pathologic conditions of the peroneal tendons at US and MR imaging and understand the various treatment options for peroneal tendon and SPR superior peroneal retinaculum injuries. Online supplemental material is available for this article.

Shear-wave elastography: Basic physics and musculoskeletal applications

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 tissues 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.

Ultrasound Elasticity Imaging for Determining the Mechanical Properties of Human Posterior Tibial Tendon: A Cadaveric Study

Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, they could be used to quantify the severity of tendonosis and help determine the appropriate treatment. The goal of this cadaveric study was, therefore, to develop and validate ultrasound elasticity imaging (UEI) as a potentially noninvasive technique for quantifying tendon mechanical properties. Five human cadaver feet were mounted in a materials testing system (MTS), while the posterior tibial tendon (PTT) was attached to a force actuator. A portable ultrasound scanner collected 2-D data during loading cycles. Youngs modulus was calculated from the strain, loading force, and cross-sectional area of the PTT. Average Youngs modulus for the five tendons was (0.45 ± 0.16 GPa) using UEI, which was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52 ± 0.18 GPa). We also calculated the scaling factor (0.12 ± 0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the PTT, and as a clinical tool, help guide treatment decisions for advanced PTTD and other tendinopathies.

Biomechanical Comparison of External Fixation and Compression Screws for Transverse Tarsal Joint Arthrodesis.

Background: Transverse tarsal joint arthrodesis is commonly performed in the operative treatment of hindfoot arthritis and acquired flatfoot deformity. While fixation is typically achieved using screws, failure to obtain and maintain joint compression sometimes occurs, potentially leading to nonunion. External fixation is an alternate method of achieving arthrodesis site compression and has the advantage of allowing postoperative compression adjustment when necessary. However, its performance relative to standard screw fixation has not been quantified in this application. We hypothesized that external fixation could provide transverse tarsal joint compression exceeding that possible with screw fixation. Methods: Transverse tarsal joint fixation was performed sequentially, first with a circular external fixator and then with compression screws, on 9 fresh-frozen cadaveric legs. The external fixator was attached in abutting rings fixed to the tibia and the hindfoot and a third anterior ring parallel to the hindfoot ring using transverse wires and half-pins in the tibial diaphysis, calcaneus, and metatarsals. Screw fixation comprised two 4.3 mm headless compression screws traversing the talonavicular joint and 1 across the calcaneocuboid joint. Compressive forces generated during incremental fixator foot ring displacement to 20 mm and incremental screw tightening were measured using a custom-fabricated instrumented miniature external fixator spanning the transverse tarsal joint. Results: The maximum compressive force generated by the external fixator averaged 186% of that produced by the screws (range, 104%-391%). Fixator compression surpassed that obtainable with screws at 12 mm of ring displacement and decreased when the tibial ring was detached. No correlation was found between bone density and the compressive force achievable by either fusion method. Conclusion: The compression across the transverse tarsal joint that can be obtained with a circular external fixator including a tibial ring exceeds that which can be obtained with 3 headless compression screws. Screw and external fixator performance did not correlate with bone mineral density. This study supports the use of external fixation as an alternative method of generating compression to help stimulate fusion across the transverse tarsal joints. Clinical Relevance: The findings provide biomechanical evidence to support the use of external fixation as a viable option in transverse tarsal joint fusion cases in which screw fixation has failed or is anticipated to be inadequate due to suboptimal bone quality.

Minimizing strain error for in vivo ultra-sound elasticity imaging of human tendon

Ultrasound elasticity imaging (UEI) is a noninvasive method for characterizing mechanical properties of soft tissue. This technique potentially provides important feedback for making treatment decision for advanced tendinopathies, such as posterior tibial tendon dysfunction (PTTD). Highly variable lateral strain along the length of the tendon has been observed during human experiments. To better understand the in vivo results, a dynamic ultrasound model of the PTT under cyclical loading was developed to analyze factors that affect tracking error (e.g., strain magnitude and out-of-plane motion) and compare different methods for calculating strain. The simulations demonstrated that linear fitting of the lateral displacement along the length of the tendon (“Method A”) produced less error for displacement and strain calculations compared to the median of the displacement gradients over the region-of-interest (“Method B”). Also, when out-of-plane motion was less than one acoustic wavelength, the strain error was 5.0 ± 4.2% for Method A and 8.3 ± 8.3% for Method B. Out-of-plane motion greater than one acoustic wavelength, produced large strain errors using either method. These results suggest that a linear fit of the displacements along the imaged portion of the tendon is an overall better approach for estimating lateral strain. Optimizing the imaging protocol and data analysis for UEI will lead to a more accurate and quantitative estimate of the mechanical properties of human tendon to help with the diagnosis, staging and treatment decisions for tendinopathies.