Accuracy of enhanced and unenhanced MRI in diagnosing scaphoid proximal pole avascular necrosis and predicting surgical outcome.

PURPOSE: Determine the sensitivity, specificity and accuracy of unenhanced and enhanced MRI in diagnosing scaphoid proximal pole (PP) avascular necrosis (AVN) and correlate whether MRI can help guide the selection of a vascularized or nonvascularized bone graft. METHODS: The study was approved by the IRB. Two MSK radiologists independently performed a retrospective review of unenhanced and enhanced MRIs from 18 patients (16 males, 2 females; median age, 17.5 years) with scaphoid nonunions and surgery performed within 65 days of the MRI. AVN was diagnosed on the unenhanced MRI when a diffusely decreased T1-W signal was present in the PP and on the enhanced MRI when PP enhancement was less than distal pole enhancement. Surgical absence of PP bleeding was diagnostic of PP AVN. Postoperative osseous union (OU) was assessed with computed tomography and/or radiographs. RESULTS: Sensitivity, specificity and accuracy for PP AVN were 71, 82 and 78% for unenhanced and 43, 82 and 67% for enhanced MRI. Patients with PP AVN on unenhanced MRI had 86% (6/7) OU; 100% (5/5) OU with vascularized bone grafts and 50% (1/2) OU with nonvascularized grafts. Patients with PP AVN on enhanced MRI had 80% (4/5) OU; 100% (3/3) OU with vascularized bone grafts and 50% (1/2) OU with nonvascularized grafts. Patients with viable PP on unenhanced and enhanced MRI had 91% (10/11) and 92% (12/13) OU, respectively, all but one with nonvascularized graft. CONCLUSIONS: When PP AVN is evident on MRI, OU is best achieved with vascularized grafts. If PP AVN is absent, OU is successful with nonvascularized grafts.

Trigger digit release: rates of surgery and complications as indicated by a United States Medicare database.

A United States insurance database was examined for trigger digit release using International Classification of Diseases, 9th Revision diagnoses and procedures or Current Procedural Terminology codes. Complications after trigger digit release, including stiffness, infection and revision surgery, were assessed. A total of 209,634 patients who underwent trigger digit release were included. The rate of trigger digit release increased significantly from 2005 to 2012, with the middle finger the most frequently released. The rate of postoperative stiffness was low, ranging from 0.8% to 1.6% depending on the operated digit. The rate of postoperative infection was lower, ranging from 0.5% to 0.6%. The need for revision within 3 years of initial trigger digit release was also low, ranging from 0.3% to 0.8%. Complications, including infection, stiffness and revision surgery, occur infrequently, but certain factors, including diabetes, Dupuytren's disease, smoking, rheumatoid arthritis, obesity and age, increase risk. LEVEL OF EVIDENCE: Therapeutic Level III, Retrospective comparative study.

Differential effects of embryonic immobilization on the development of fibrocartilaginous skeletal elements.

The importance of mechanical influences during skeletal development has been well established in both experimental studies and computer models. Under conditions of embryonic immobilization, it has been observed that the early stages of joint formation proceed normally (up to and including interzone formation), but the later stages of joint cavitation and maintenance are impaired, resulting in fusion of the cartilaginous elements across the presumptive joint line. Two structures in particular are noticeably absent from late-stage synovial joints in immobilized chick embryos: the menisci of the tibiofemoral joint and the plantar tarsal sesamoid of the tibiotarsal joint. Both of these fibrocartilaginous structures are known to serve mechanical functions in postnatal animals, helping to distribute loads within the joint and, in the case of sesamoid structures, to provide a mechanical advantage to muscles acting across the joint. We demonstrate in this study that embryonic immobilization differentially affects the developmental fate of these two distinct fibrocartilages. The absence of the plantar tarsal sesamoid in late-stage immobilized embryos is due to a failure in the initial formation of this structure. In contrast, the early stages of meniscus formation proceed normally. Without the normal mechanical stimuli of skeletal muscle contractions, however, the meniscus fails to mature and ultimately degenerates.

Tendon tissue engineering: adipose-derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems.

Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable, and when combined with readily available autologous cells, may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stem cells (ADSCs) that were cultured on a poly(DL-lactide-co-glycolide) PLAGA fiber scaffold and compared to a PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker, was upregulated seven- to eightfold at 1 week with GDF-5 treatment when cultured on a 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by fourfold starting at 1 week on treatment with 100 ng mL(-1) GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on a PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration.

Growth differentiation factor-5 regulation of extracellular matrix gene expression in murine tendon fibroblasts.

The synthesis and organization of extracellular matrix (ECM) of tendon, in resting and states of repair, are governed by fibroblasts. Growth differentiation factor-5 (GDF-5) may enhance the cellular response to tendon injury, thus improving the structural outcome of the regenerative tissue. This study was an attempt to identify potential mechanisms controlling the response of fibroblasts to injury and GDF-5, in the pursuit of improved tissue regeneration. There were two sets of experiments. Isolated mice Achilles tendon fibroblasts were treated with different concentrations of rGDF-5 (0-100 ng/ml) for 0-12 days in cell culture. The temporal effect of rGDF-5 on ECM gene expression was analysed for type I collagen and aggrecan expression. Microarray and gene expression analysis were performed on cells treated with 100 ng/ml for 4 days. Forty-five mice underwent bilateral mid-substance Achilles tendon tenotomy and suture repair. Repair sites were injected with 10 µg rGDF-5 or saline. Tendons were assessed histologically at 2, 4 and 6 weeks. Expression of ECM genes procollagen IX, aggrecan, matrix metalloproteinase 9 and fibromodulin were upregulated. Proinflammatory reaction genes were downregulated. rGDF-5 led to an increase in total DNA, glycosaminoglycan (GAG) and hydroxyproline (OHP). The OHP:DNA ratio of fibroblast cultures was increased over all time points, with increased GAG:DNA at day 12. rGDF-5 treatment showed improved collagen organization over controls. The results delineate the mode of action of rGDF-5 at the cellular and gene level. rGDF-5 could play a role in tendon repair and be used for future therapies that promote tendon healing.