Faculty Bibliography

UNLABELLED:Osteochondral lesions of the talus (OLT) are commonly associated with traumatic injury to the ankle joint. Treatment options depend on the grade, location, and size of the lesion. Operative intervention is frequently required with initial management involving marrow stimulation techniques, such as microfracture/curettage. Larger lesions often require a secondary procedure, such as osteochondral transplantation or autologous chondrocyte implantation. The advent of particulated juvenile articular cartilage (PJAC) provides an alternative method for OLTs refractory to traditional treatments. This article describes the technique of PJAC transplantation for the treatment of osteochondral lesions of the talus. LEVEL OF EVIDENCE/METHODS:Level V, expert opinion.

BACKGROUND:Tendinopathy is a clinical problem for which treatment shows mixed results and treatment options are limited. Gene expression signatures early in the mechanotransduction pathway can accurately predict risk and correlate with different clinical outcomes. Studies aimed at elucidating the molecular mechanisms of tendinopathy have focused on small cohorts of genes that show an incomplete picture of the degeneration process. This study compared the effect of cyclic strain on gene expression in tendon cells from normal tendon and chronically painful areas of tendinopathy in 3 patients. METHODS:We measured a panel of mechanotransduction genes and cytoskeletal tensional balance with and without cyclic strain, which disrupts connective tissue synthetic-degradative equilibrium. Normal and degenerative tendons were obtained from patients undergoing surgery to treat chronic painful tendinopathy. A cyclic strain model was established to measure cytoskeletal tensional homeostasis. RESULTS:Prior to cyclic strain, the normal tendon cells exhibited varying patterns of elevated expression of 7 genes compared with degenerative tendon cells. In response to cyclic strain, gene expression of COL1A1, ITGA6, CTNNA1, and CLEC3B was up-regulated in normal tendon cells. Cyclic strain had no effect on degenerative tendon cells. Cyclic strain exacerbated the inhibition of protein synthesis in both cell types, especially in the degenerative tendon cells. CONCLUSION/CONCLUSIONS:Alterations in the pattern of gene expression are suggestive of a dynamic equilibrium between synthesis and degradation, whereby cell adhesion molecules are predominantly up-regulated to facilitate cellular reorientation in response to their altered functional environment. CLINICAL RELEVANCE/CONCLUSIONS:These data might have future applications, including the identification of markers for early diagnosis, targets for drug design, and indicators for treatment responsiveness and prognosis.

OBJECTIVES/OBJECTIVE:The purpose of this study was to investigate the efficacy of a composite surgical mesh for delivery of mesenchymal stem cells (MSCs) in tendon repair. METHODS:The MSC-loaded mesh composed of a piece of conventional surgical mesh and a layer of scaffold, which supported MSC-embedded alginate gel. A 3-mm defect was surgically created at the Achilles tendon-gastrocnemius/soleus junction in 30 rats. The tendon defects were repaired with either 1) MSC-loaded mesh; or 2) surgical mesh only; or 3) routine surgical suture. Repaired tendons were harvested at days 6 and 14 for histology, which was scored on the bases of collagen organization, vascularity and cellularity, and immunohistochemisty of types I and III collagen. RESULTS:In comparison with the other two repair types, at day 6, the MSC-loaded mesh significantly improved the quality of the repaired tendons with dense and parallel collagen bundles, reduced vascularity and increased type I collagen. At day 14, the MSC-loaded mesh repaired tendons had better collagen formation and organization. CONCLUSION/CONCLUSIONS:The MSC-loaded mesh enhanced early tendon healing, particularly the quality of collagen bundles. Application of the MSC-loaded mesh, as a new device and MSC delivery vehicle, may benefit to early functional recovery of the ruptured tendon.

BACKGROUND:Tendon healing is a slow and complicated process that results in inferior structural and functional properties when compared to healthy tendon tissue. It may be possible to improve outcomes of tendon healing with enhancement of biological aspects of the repair including tissue structure, organization, and composition. The purpose of this study was to determine whether use of a stem cell-bearing suture improves Achilles tendon healing in a rat model. METHODS:The Achilles tendon was transected in 108 bilateral hind limbs from 54 rats. Each limb was randomized to repair with suture only (SO), suture plus injection (SI) of mesenchymal stem cells (MSCs) at the repair site, or suture loaded with MSCs (suture with stem cells, SCS). One half of the animals were randomly sacrificed at 14 and 28 days after surgery and the Achilles tendon was harvested. From each repair group at each time point, 12 limbs were randomized to biomechanical testing and 6 to histologic analysis. Tendons were loaded using a 223-N load cell at 0.17 mm/s. A blinded pathologist scored the histology sections. RESULTS:Ultimate failure strength (N/mm(2)) was significantly higher in the SI and SCS groups versus the SO group. In the SI group, ultimate failure strength decreased significantly at 28 days versus 14 days. Histology score in the SCS group was significantly lower (better) than in both other groups (P ≤ .001). Histology findings at day 28 were significantly higher versus day 14 for all groups (P = .01). CONCLUSIONS:Both the SI and the SCS groups had significantly higher ultimate failure strength versus the SO group, and strength was maintained at 28 days in the SCS group but not in the SI group. Histology in the SCS group was significantly better than in both other groups. CLINICAL RELEVANCE/CONCLUSIONS:These findings in a rat model suggest that the use of stem cells enhances healing after Achilles repair and that embedding of stem cells directly into suture offers sustained early benefit to tendon healing.

Operative foot and ankle osteomyelitis is challenging for orthopedic surgeons because of the area’s unique anatomy, high trauma incidence, local and systemic disease effects, and often limited space. Standard treatment includes aggressive operative debridement with local and systemic antibiotic administration to control infection. Dead space management is critical yet technically demanding. The authors report a modified antibiotic cement bead therapy technique in which antibiotic sticks, minnows, and mushroom-shaped plugs are used to strike a balance between the stability of the load-bearing unit and radical removal of infection to preserve a functional foot. Three cases are presented.

OBJECTIVES/OBJECTIVE:Circulating mesenchymal stem cells (MSCs) participate in fracture healing and can be used to enhance fracture healing. This study investigated how CD271-selected MSCs travel in circulation and when is the optimal time to apply MSCs intravenously during fracture healing. METHODS:Based on the expression of CD271, MSCs were isolated from human bone marrow and labeled with cypate, a near-infrared fluorochrome. A unilateral closed fracture was created at the femur in immunodeficient mice. The cypate-labeled MSCs were injected into the tail vein of the mice at days 1 and 3 after fracture and were tracked by near-infrared imaging. The mice were euthanized at 3 weeks after fracture. Immunohistochemistry was performed to detect human MSCs at the fracture sites. Migration of CD271-selected MSCs, under the influence of stem cell-derived factor-1, was assessed in vitro. RESULTS:Intravenously injected at day 1, but not day 3, after fracture, CD271-selected MSCs accumulated at the fracture sites significantly and lasted for at least 7 days. All fractures, with or without MSC injections, healed in 3 weeks. Human cells were localized at the fracture sites in mice by immunohistochemistry. CD271-selected MSCs migrated toward the medium contained stem cell-derived factor-1 in vitro. CONCLUSIONS:After intravenous injection, CD271-selected MSCs were recruited to the fracture sites. The stages of fracture healing influenced the homing of culture-expanded MSCs. In mice, an optimal window of intravenous injection of MSCs was around 24 hours after fracture. CLINICAL RELEVANCE/CONCLUSIONS:Intravenous application of MSCs may serve as a practical route to deliver stem cells for the treatment of fracture nonunion and delayed union.

Plantar fat pad (PFP) is a tissue structure that absorbs the initial impact of walking and running and ultimately bears body weight at standing. This study was designed to quantify the histomorphological changes of the PFP in aged rats. The most medial PFP was dissected from the hind feet of young rats (4 months old, n = 6) and aged rats (24 months old, n = 6). Histological structure and cellular senescence of PFP were analyzed stereologically and histomorphometrically. Immunohistochemistry of matrix metalloproteinase 9 (MMP9) was also performed on PFP tissue sections. Compared with young rats, the thickness of epidermis, dermis and septa of the PFP were significantly reduced in the aged rats. The total volume of adipose tissue in the PFP of aged rats was only about 65% of that in the young rats. The microvascular density and the number of fat pad units (FPU), a cluster of adipocytes enclosed by elastin septa, in the PFP were unchanged in the aged rats. In the aged rats, the number of adipocytes per FPU was reduced but the number of simple adipocyte clusters, without surrounding septa, was increased. The shift of the types of adipocyte clusters in the aged PFP was accompanied by degradation of elastin fibers and increased expression of MMP9. In conclusion, the PFP, particularly the elastic septa, degenerates significantly in aged rats and this may contribute to the pathology of PFP-related diseases.

BACKGROUND:Numerous modalities are used today to treat symptomatic osteochondral lesions in the ankle. However, there are ongoing challenges with the treatment of certain lesions, and concerns exist regarding long-term effectiveness. METHODS:The purpose of the study was to collect clinical outcomes of pain and function in retrospectively and prospectively enrolled patients treated with particulated juvenile cartilage for symptomatic osteochondral lesions in the ankle. This study collected outcomes and incidence of reoperations in standard clinic patients. The analysis presented here includes final follow-up to date for 12 males and 11 females representing 24 ankles. Subjects had an average age at surgery of 35.0 years and an average body mass index of 28 ± 5.8. Fourteen ankles had failed at least 1 prior bone marrow stimulation procedure. The average lesion size was 125 ± 75 mm(2), and the average depth was 7 ± 5 mm. In conjunction with the treatment, 9 (38%) ankles had 1 concomitant procedure and 9 (38%) had more than 1 concomitant procedure. Clinical evaluations were performed with an average follow-up of 16.2 months. RESULTS:Average outcome scores at final follow-up were American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Scale 85 ± 18 with 18 (78%) ankles demonstrating good to excellent scores, Short-Form 12 Health Survey (SF12) physical composite score 46 ± 10, SF12 mental health composite score 55 ± 7.1, Foot and Ankle Ability Measure (FAAM) activities of daily living 82 ± 14, FAAM Sports 63 ± 27, and 100-mm visual analog scale for pain 24 ± 25. Outcomes data divided by lesion size demonstrated 92% (12/13) good to excellent results in lesions 10 mm or larger and those smaller than 15 mm. To date, 1 partial graft delamination has been reported at 16 months. CONCLUSIONS:Preliminary data from a challenging clinical population with large, symptomatic osteochondral lesions in the ankle suggest that treatment with particulated juvenile cartilage could improve function and decrease pain. Longer follow-up and additional subjects are needed to evaluate improvement level and ideal patient indications. LEVEL OF EVIDENCE/METHODS:Level IV, case series.