Background Donor site morbidity, limited numbers of cells, loss of phenotype during ex vivo expansion, and age-related decline in chondrogenic activity present critical obstacles to the use of autologous chondrocyte implantation for cartilage repair. Chondrocytes from juvenile cadaveric donors may represent an alternative to autologous cells. Hypothesis/Purpose The authors hypothesized that juvenile chondrocyte would show stronger and more stable chondrogenic activity than adult cells in vitro and that juvenile cells pose little risk of immunologic incompatibility in adult hosts. Study Design Controlled laboratory study. Methods Cartilage samples were from juvenile (<13 years old) and adult (> 13 years old) donors. The chondrogenic activity of freshly isolated human articular chondrocytes and of expanded cells after monolayer culture was measured by proteoglycan assay, gene expression analysis, and histology. Lymphocyte proliferation assays were used to assess immunogenic activity. Results Proteoglycan content in neocartilage produced by juvenile chondrocytes was 100-fold higher than in neocartilage produced by adult cells. Collagen type II and type IX mRNAs in fresh juvenile chondrocytes were 100- and 700-fold higher, respectively, than in adult chondrocytes. The distributions of collagens II and IX were similar in native juvenile cartilage and in neocartilage made by juvenile cells. Juvenile cells grew significantly faster in monolayer cultures than adult cells (p = 0.002) and proteoglycan levels produced in agarose culture was significantly higher in juvenile cells than in adult cells after multiple passages (p < 0.001). Juvenile chondrocytes did not stimulate lymphocyte proliferation. Conclusions These results document a dramatic age related decline in human chondrocyte chondrogenic potential and show that allogeneic juvenile chondrocytes do not stimulate an immunologic response in vivo. Clinical Relevance Juvenile human chondrocytes have greater potential to restore articular cartilage than adult cells, and may be transplanted without the fear of rejection, suggesting a new allogeneic approach to restoring articular cartilage in older individuals.

To avoid misinterpretation of the MDTA, we recommend using the AP view to quantify supramalleolar alignment as it is less sensitive to changes in positioning of the foot-ankle. When acquiring an AP film, the x-ray beam should be directed along the horizon to ensure consistent assessment of the MDTA across patients.

Background The use of allogenic juvenile chondrocytes or autologous chondral fragments has shown promising laboratory results for the repair of chondral lesions. Hypothesis/Purpose The purpose of the study was to evaluate in vitro the extracellular matrix production of mixed adult/juvenile cultures of both chondrocytes (part 1) and minced cartilage fragments (part 2). The authors hypothesized that juvenile chondrocytes would not affect matrix production when mixed with adult chondrocytes or cartilage fragments. Study design Controlled laboratory study. Methods Cartilage sources consisted of three adult and three juvenile (human) donors. In part 1, per each donor, juvenile chondrocytes were mixed with adult chondrocytes in five different proportions: 100, 50, 25, 12.5 and 0 %. Three-dimensional cultures in low melt agarose were performed. At 6 weeks, biochemical and histological analyses were performed. In part 2, isolated adult, isolated juvenile, and mixed three-dimensional cultures (1:1) were performed with chondral fragments (<1mm), both with low melt agarose and a hyaluronic acid scaffold. At 2 and 6 weeks, cultures were evaluated with biochemical and histological analyses. Results Part 1: biochemical and histological analyses showed that isolated juvenile cultures performed significantly better than mixed and isolated adult cultures. No significant differences were noted between mixed cultures (1:1) and isolated adult cultures. Part 2: biochemical and histological results at 6 weeks showed that mixed cartilage fragment cultures performed better than isolated adult cultures in terms of PG/DNA ratio (p=0.014), percentage of safranin-O positive cells (p=0.012), Bern score (p=0.001), and Collagen type II. No statistical difference was noted between juvenile and mixed cultures. Conclusion Extracellular matrix production of juvenile chondrocytes is inhibited by adult chondrocytes. The addition of juvenile cartilage fragments to adult fragments improves matrix production, with a positive interaction between the two sources. Clinical relevance Even if the underlying mechanisms are still unknown, this study describes the behavior of juvenile/adult co-cultures using both chondrocytes and cartilage fragments, with potential for new research and clinical applications.

Background Short stem cementless femoral components were developed to aid insertion through smaller incisions, preserve metaphyseal bone, and potentially decrease or limit the incidence of thigh pain. Despite some clinical success, the senior author (DDG) believed a higher percentage of his patients who had received a cementless short stem design were experiencing thigh pain, which, coupled with concerns about bone ingrowth fixation, motivated the review of this case series.Questions/purposes (1) What is the proportion of patients treated with a short stem cementless THA femoral component that develop thigh pain and what are the hip scores of this population? (2) What are the radiographic results, specifically with respect to bone ingrowth fixation and stress shielding, of this design? (3) Are there particular patient or procedural factors that are associated with thigh pain with this short stem design? Methods Two hundred sixty-one primary THAs were performed in 238 patients by one surgeon between November 2010 and August 2012. During this time period, all patients undergoing primary THA by this surgeon received the same cementless short titanium taper stem. Seven patients (eight hips) died and five patients (five hips) were lost to followup, leaving 226 patients (248 hips) with a mean followup of 3 years (range, 2-5 years). Patients rated their thigh pain during activity or rest at final followup on a 10-point visual analog scale. Harris hip scores (HHS) were obtained at every clinic appointment. Thigh pain was evaluated at the final followup or by contacting the patient by phone. Radiographs were evaluated for boneimplant fixation, bone remodeling, and osteolysis. An attempt was made to correlate thigh pain with patient demographics, implant specifications, or radiographic findings. Results Seventy-six percent of hips (180 of 238) had no thigh pain, 16% of hips (37 of 238) had mild thigh pain, and 9% (21 of 238) had moderate or severe thigh pain. Preoperatively, mean HHS was 47 (SD, 16) and at last followup, mean HHS was 88 (SD, 13). There were two femoral revisions, one for severe thigh pain and the other for infection. All but two components demonstrated bone ingrowth fixation (99%). Femoral stress shielding was mild in 64% of hips (135 of 212), moderate in 0.5% (one of 212), and severe in no hips. There is an inverse linear

Advanced imaging such as CT or MRI may better describe ankle alignment.