Faculty Bibliography

OBJECTIVES/OBJECTIVE:To assess high-bandwidth and compressed sensing-(CS)-SEMAC turbo spin echo (TSE) techniques for metal artifact reduction MRI of total ankle arthroplasty (TAA) implants. METHODS:Following institutional approval and consent, 40 subjects with TAA implants underwent 1.5-T MRI prospectively. Evaluations included bone-implant interfaces, anatomical structures, abnormal findings and differential diagnoses before and after MRI. AUCs of P-P plots were used to determine superiority. Statistical differences were evaluated with McNemar and chi-square tests. P-values ≤ 0.05 were considered significant. RESULTS:CS-SEMAC TSE was superior to high-bandwidth TSE in showing the bone-implant interfaces (AUC=0.917), periprosthetic bone, tendons and joint capsule (AUC=0.337-0.766), bone marrow oedema (43 % difference, p=0.041), interface osteolysis (63 %, p=0.015), tendinopathy (62 %, p=0.062), periprosthetic fractures (60 %, p=0.250), synovitis (43 %, p=0.250), as well as reader confidence for bone marrow oedema (p=<0.001), fracture (p=0.001), interface osteolysis (p=0.003), synovitis (p=0.027) and tendinopathy (p=0.034). The number of differential diagnoses in symptomatic subjects after the MRI with CS-SEMAC decreased from 3 (1-4) to 1 (1-2) (p<0.001). CONCLUSIONS:MRI of TAA implants with CS-SEMAC improves the diagnosis of interface osteolysis, periprosthetic bone marrow oedema, fractures and tendinopathy when compared to high-BW TSE, and has a positive effect on patient management. KEY POINTS/CONCLUSIONS:• High-bandwidth TSE and compressed sensing SEMAC improve MRI of ankle arthroplasty implants. • Compressed sensing SEMAC improves bone-implant interfaces, periprosthetic bone, tendons and joint capsule visibility. • Compressed sensing SEMAC improves the diagnosis of osteolysis, tendinopathy, fractures and synovitis. • MRI decreases the number of clinical differential diagnoses of painful ankle arthroplasty implants.

Foot and ankle injections are useful diagnostic and therapeutic tools, particularly when the pain etiology is uncertain. A variety of foot and ankle injuries and pathologies, including degenerative joint disease, plantar fasciitis and different tendinopathies are amenable to injections. Understanding the foot and ankle anatomical landmarks, a thorough physical exam and knowledge of the different injection techniques is key for a successful approach to different pathologies. The objective of this study is to review the use of foot and ankle injections in the orthopaedic literature, present the readers with the senior author's experience and provide a comprehensive clinical guideline to the most common foot and ankle diagnostic and therapeutic injections.

Introduction/UNASSIGNED:The treatment of osteochondral lesions of the talus (OLTs) recalcitrant to non-surgical interventions is challenging. Particulated juvenile cartilage allograft transplantation (PJCAT) has become a viable treatment option, obviating the need for an osteotomy or second-stage surgery and eliminating risk of donor site morbidity. Short-term outcomes have been promising, but failures associated with PJCAT have not been well described. Case Report/UNASSIGNED:Four patients with OLTs who had continued symptoms after PJCAT underwent a second-look arthroscopic evaluation. The quality of cartilage repair was evaluated using the international cartilage repair society (ICRS) score. Biopsy of the repair was taken for histological analysis. Two patients demonstrated a lack of integration of the allograft into the surrounding cartilage, and two had failures associated with impingement. Three patients' repairs were consistent with a Grade III ICRS score and one with a Grade II score. Histological examination demonstrated fibrotic repair tissue (Type 1 collagen) with depleted proteoglycans and Type II collagen. Conclusion/UNASSIGNED:There were no obvious patients or surgical factors associated with poor outcomes. Integration of PJCAT with surrounding cartilage appears to be affected by biological and mechanical factors. Further, understanding of factors influencing PJCAT integration will help develop more specific indications for use.

Charcot neuroarthropathy (CNA) often presents as a diabetic foot complication. The role of synovial mesenchymal stem cells (syn-MSCs) in the pathogenesis of CNA is unclear. Synovial samples were collected, for isolation of syn-MSCs, from diabetic patients with CNA (n=7) and non-diabetic patients with intra-articular fracture or normal joints (non-CNA; n=7) during foot surgery. The syn-MSCs in the CNA and non-CNA groups were characterized comparatively. The average number of colonies formed in the CNA group was 6±3.5 per half plate (10mm in diameter), while it was 43±21.6 in the non-CNA group (p<0.05). The average size (pixels) of the colonies in the CNA group was smaller than that in the non-CNA group. When the colonies were stratified into high-, medium- and low-density subgroups, colonies in the high-density subgroup of the CNA group were reduced in density. Expression of PPAR-γ, RUNX2, Sox9 and type II collagen by syn-MSCs in the CNA group was decreased during adipogenic, osteogenic and chondrogenic differentiation as compared with the non-CNA group. In conclusion, syn-MSCs in CNA joints were reduced in number, with declined differentiation potentials. The high-density subpopulation of the syn-MSCs was particularly affected by the pathology of CNA.

The biology and function of orthotopic transplantation of Achilles tendon allograft are unknown. Particularly, the revitalization of Achilles allograft is a clinical concern. Achilles allografts were harvested from donor rats and stored at -80 °C. Subcutaneous adipose tissue was harvested from the would-be allograft recipient rats for isolation of mesenchymal stem cells (MSCs). MSCs were cultured with growth differentiation factor-5 (GDF-5) and applied onto Achilles allografts on the day of transplantation. After the native Achilles tendon was resected from the left hind limb of the rats, Achilles allograft, with or without autologous MSCs, was implanted and sutured with calf muscles proximally and calcaneus distally. Animal gait was recorded presurgery and postsurgery weekly. The animals were sacrificed at week 4, and the transplanted Achilles allografts were collected for biomechanical testing and histology. The operated limbs had altered gait. By week 4, the paw print intensity, stance time, and duty cycle (percentage of the stance phase in a step cycle) of the reconstructed limbs were mostly recovered to the baselines recorded before surgery. Maximum load of failure was not different between Achilles allografts, with or without MSCs, and the native tendons. The Achilles allograft supplemented with MSCs had higher cellularity than the Achilles allograft without MSCs. Deposition of fine collagen (type III) fibers was active in Achilles allograft, with or without MSCs, but it was more evenly distributed in the allografts that were incubated with MSCs. In conclusion, orthotopically transplanted Achilles allograft healed with host tissues, regained strength, and largely restored Achilles function in 4 wk in rats. It is therefore a viable option for the reconstruction of a large Achilles tendon defect. Supplementation of MSCs improved repopulation of Achilles allograft, but large animal models, with long-term follow up and cell tracking, may be required to fully appreciate the functional benefits of MSCs.

This study investigated the therapeutic potential of low-intensity pulsed ultrasound (LIPUS) in post-traumatic osteoarthritis (PTOA). Intra-articular fracture of the medial tibial plateau was surgically created in 30 rats. LIPUS was applied to the operated joints either for the first 2 wk (LIPUS_1-2 group) or in weeks 4 and 5 after intra-articular fracture (LIPUS_4-5 group). In controls, the operated knees were not treated with LIPUS (LIPUS₀ group). The rats were monitored with weekly gait analysis and euthanized at week 8. Among the altered gait parameters, the maximal and average paw print areas in the LIPUS_1-2 and LIPUS_4-5 groups, but not the LIPUS₀ group, had either reached baseline or significantly recovered (70%, p <0.05) by week 8. PTOA pathology in both the LIPUS_1-2 and LIPUS_4-5 groups was less severe than that in the LIPUS₀ group (Mankin score: 5.4 and 4.5 vs. 8.8, p <0.05). In conclusion, LIPUS treatment partially improved the gait of the affected limbs and reduced cartilage degeneration in PTOA.

Our goal was to develop a novel technique for inducing Achilles tendinopathy in animal models which more accurately represents the progressive histological and biomechanical characteristic of chronic Achilles tendinopathy in humans. In this animal research study, forty-five rabbits were randomly assigned to three groups and given bilateral Achilles injections. Low dose (LD group) (n = 18) underwent a novel technique with three low-dose (0.1mg) injections of collagenase that were separated by two weeks, the high dose group (HD) (n = 18) underwent traditional single high-dose (0.3mg) injections, and the third group were controls (n = 9). Six rabbits were sacrificed from each experimental group (LD and HD) at 10, 12 and 16 weeks. Control animals were sacrificed after 16 weeks. Histological and biomechanical properties were then compared in all three groups. At 10 weeks, Bonar score and tendon cross sectional area was highest in HD group, with impaired biomechanical properties compared to LD group. At 12 weeks, Bonar score was higher in LD group, with similar biomechanical findings when compared to HD group. After 16 weeks, Bonar score was significantly increased for both LD group (11,8±2,28) and HD group (5,6±2,51), when compared to controls (2±0,76). LD group showed more pronounced histological and biomechanical findings, including cross sectional area of the tendon, Young's modulus, yield stress and ultimate tensile strength. In conclusion, Achilles tendinopathy in animal models that were induced by serial injections of low-dose collagenase showed more pronounced histological and biomechanical findings after 16 weeks than traditional techniques, mimicking better the progressive and chronic characteristic of the tendinopathy in humans.

This study described and histologically characterized a cyst-like lesion (CLL) at the chondro-osseous junction. Rat knees (n = 12), with or without excessive running-induced osteoarthritis (OA), were used for counting the incidence, morphological measurements, immunohistochemistry of the CLL. A typical CLL, appearing as a void space in the matrix, was located on the tidemark at the chondro-osseous junction. The content of the CLL included types II and VI collagen, proteoglycans but not intact chondrocytes. At least one CLL was found in 5/6 osteoarthritic knees and only 2/6 in the non-osteoarthritic knees. The margin of the CLL was depleted of proteoglycans. The chondrocytes around the lesion were deformed and occasionally apoptotic. Matrix metalloproteinase 13 and vascular endothelial growth factor receptor were not detected in and around the CLL. CLLs disrupt the integrity of cartilage at a mechanically critical location-the chondro-osseous junction. The significance of the CLL in cartilage biology and its potential role in OA pathogenesis warrant further investigation.

BACKGROUND:The 3-dimensional nature of adult acquired flatfoot deformity can be challenging to characterize using radiographs. We tested the hypothesis that measurements on weight-bearing (WB) cone-beam computed tomography (CT) images were more useful for demonstrating the severity of the deformity than non-weight-bearing (NWB) measurements. METHODS:We prospectively enrolled 12 men and 8 women (mean age, 52 years; range, 20 to 88 years) with flexible adult acquired flatfoot deformity. The subjects underwent cone-beam CT while standing (WB) and seated (NWB), and images were assessed in the sagittal, coronal, and axial planes by 3 independent observers who performed multiple measurements. Intraobserver and interobserver reliabilities were assessed with the Pearson or Spearman correlation and the intraclass correlation coefficient (ICC), respectively. Measurements were compared using paired Student t tests or Wilcoxon rank-sum tests. P < 0.05 was considered significant. RESULTS:We found that overall the measurements had substantial intraobserver and interobserver reliability on both the NWB images (mean ICC, 0.80; range, 0.49 to 0.99) and the WB images (mean ICC, 0.81; range, 0.39 to 0.99). Eighteen of 19 measurements differed between WB and NWB cone-beam CT images, with more pronounced deformities on the WB images. The most reliable measurements, based on intraobserver and interobserver reliabilities and the difference between WB and NWB images, were the medial cuneiform-to-floor distance, which averaged 29 mm (95% confidence interval [CI] = 28 to 31 mm) on the NWB images and 18 mm (95% CI = 17 to 19 mm) on the WB images, and the forefoot arch angle (mean, 13° [95% CI = 12° to 15°] and 3.0° [95% CI = 1.4° to 4.6°], respectively) in the coronal view and the cuboid-to-floor distance (mean, 22 mm [95% CI = 21 to 23 mm] and 17 mm [95% CI = 16 to 18 mm], respectively) and the navicular-to-floor distance (mean, 38 mm [95% CI = 36 to 40 mm] and 23 mm [95% CI = 22 to 25 mm], respectively) in the sagittal view. CONCLUSIONS:Measurements analogous to traditional radiographic parameters of adult acquired flatfoot deformity are obtainable using high-resolution cone-beam CT. Compared with NWB images, WB images better demonstrated the severity of osseous derangement in patients with flexible adult acquired flatfoot deformity. LEVEL OF EVIDENCE/METHODS:Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:Aseptic component loosening is a leading cause of revision for total ankle replacement. Different operative approaches for resecting the tibia and talus impact the bony support for the prostheses due to variations in both bone density and resection area, and may therefore impact loosening performance. METHODS:Computed tomography data from 116 subjects were obtained, and solid models of the talus and tibia were generated. Bone density, resection area, and bony support were measured on a series of flat resections for each subject, at multiple resection depths. Similar measurements were performed using a series of subject-specific, anatomic radius-based resections ("round resections") at multiple depths. Results were compared to assess the impact of both resection type (flat vs round) and resection depth (6-16 mm for the tibia, 2-6 mm for the talus) on bony support. RESULTS:Statistically significant decreases in bony support for both the talus and the tibia were obtained for flat resections as compared to round resections. A decrease of 8% to 19% for the tibia was seen for all resection depths; a decrease of 8% to 46% for the talus was seen, with greater decreases seen for shallower flat-cut resections. CONCLUSION/CONCLUSIONS:Bony support in total ankle arthroplasty may be decreased using flat resections compared to round resections at comparable resection depths. Estimated differences are resection-level dependent and different for the distal tibia vs the proximal talus. CLINICAL RELEVANCE/CONCLUSIONS:Biomechanical characteristics of total ankle replacement impacted by bony support of the prostheses, including implant stability and resistance to subsidence, may be improved with round resections as compared to flat-cut resections.